TW202507056A - Surface activated chemical vapor deposition and uses thereof - Google Patents

Abstract

Surface activated chemical vapor deposition (SACVD) methods and uses thereof are described herein. Polymeric coatings deposited by SACVD demonstrate high uniformity and conformality, as compared to other deposition techniques, such as initiated chemical vapor deposition (iCVD).

Description

Surface activated chemical vapor deposition and its use

The present invention belongs to the field of polymer coatings formed by surface activated chemical vapor deposition methods.

Coatings play a critical role in many industries where they are applied to surfaces for a variety of reasons such as sealing to protect surfaces from the environment, adding mechanical protection, imparting optical effects, modifying surface properties, and enhancing biological or chemical compatibility. A significant benefit of modifying surfaces with coatings is that relatively small amounts of material can be used to define surface properties over large areas without changing the properties of the bulk material. Typical processes for applying coatings include spraying, dipping, painting, and immersion in chemical baths. These coating methods utilize liquids, which add complexities associated with curing, surface tension and viscosity effects, can result in pinholes, limit conformality, and increase the minimum practical thickness of the coating.

The importance of coating conformality becomes increasingly important in many industries as substrates become more complex and the surface area to volume ratio increases. Chemical vapor deposition (CVD) is a subset of coating processes that applies the coating directly from the vapor phase. The desired coating material is synthesized directly from gaseous precursors. However, typical CVD processes rely on spatially localized energy sources to activate the chemical synthesis process, such as filaments, plasmas, UV radiation or lasers. These energy sources can cause conformality issues imposed by line-of-sight limitations, directionally dependent electric fields and high-energy molecules that react easily upon impact, which can also cause damage to the resulting coating. These factors ultimately limit the conformality of the resulting coating.

Therefore, there is a need for alternative deposition methods that allow coatings to be easily deposited without unduly limiting the conformality of the resulting coatings.

Furthermore, there is a need for improved methods for coating, for example, microelectronic device stacks, boards, electronic device assemblies, and 3-D integrated heterogeneous packages that have high aspect ratio characteristics and can benefit from coatings that exhibit high conformality while providing protection benefits.

It is therefore an object of the present invention to provide a deposition method which produces a coating with high conformality.

It is therefore also an object of the present invention to provide deposition methods in which the resulting conformal coatings can provide protection benefits to the coated substrates and devices.

Therefore, another object of the present invention is to use such methods to manufacture substrates or devices with highly conformal coatings for various applications.

Methods of surface activated chemical vapor deposition (SACVD) and their use to form highly conformal coatings are described herein. Generally, SACVD processes work by thermally assisting the formation of chemically reactive species, such as initiator radicals, directly on one or more surfaces to be coated in situ with a polymer. SACVD methods can be used to deposit one or more conformal polymer coatings on various types of substrates or devices, such as microelectronic devices, having one or more high aspect ratio features thereon. Highly conformal coatings can be formed on such devices using the SACVD methods described herein.

In the first example, surface activated chemical vapor deposition (SACVD) can be performed under isothermal conditions. Under isothermal conditions, at least one substrate or device to be coated is placed in a reaction chamber, and the reaction chamber is heated to an initiation temperature sufficient to activate one or more gaseous initiators. In such methods, heating to the initiation temperature also heats one or more surfaces of the substrate or device in the reaction chamber to decompose the one or more initiators and thereby form/deposit a polymer coating on at least a portion of the one or more surfaces of the substrate or device.

A non-limiting first example of an isothermal SACVD method includes: (i) placing the at least one substrate or device into a reaction chamber; (ii) sealing and purging the reaction chamber under vacuum; (iii) wherein the reaction chamber is at an initiation temperature sufficient to activate one or more gaseous initiators; wherein one or more surfaces of the at least one substrate or material have a surface temperature equal to or substantially equal to the initiation temperature to which the reaction chamber is heated; and (iv) flowing one or more gaseous monomers, the one or more gaseous initiators, and optionally one or more carrier gases into the reaction chamber to form the polymer coating on at least a portion of the one or more surfaces of the at least one substrate or device; wherein the partial pressure of the one or more gaseous monomers is sufficient to form the polymer coating on the portion of the one or more surfaces of the at least one substrate or device at the surface temperature.

In some embodiments, the surface temperature during step (iv) is sufficient to prevent the one or more gaseous monomers or the one or more gaseous initiators from exceeding their saturation pressure at the surface temperature.

In some cases, a polymer coating formed on one or more surfaces of at least one substrate or device has a conformality of at least about 50% as measured by a wafer stacking method; and/or wherein a polymer coating formed on one or more surfaces of at least one substrate or device has a microscale conformality of at least about 60% as measured by a microtrenching method.

Prior to step (iv), the one or more surfaces of the at least one substrate or device has a surface temperature equal to or substantially equal to the initiation temperature. During step (iv), the partial pressure of the one or more gaseous monomers is sufficient to cause the one or more gaseous monomers to adsorb on the one or more surfaces of the at least one substrate or device at the surface temperature. In addition, the partial pressure of the one or more gaseous monomers is also sufficient to form a polymer coating on the portion on the surface at the surface temperature.

A non-limiting second example of an isothermal SACVD process includes: (i) sealing and purging a reactor under vacuum; (ii) wherein the reaction chamber is at an initiation temperature sufficient to activate one or more gaseous initiators; and (iii) introducing one or more gaseous monomers, one or more gaseous initiators, and optionally one or more carrier gases into the reactor.

Prior to step (iii), one or more surfaces of the reactor have a surface temperature equal to or substantially equal to the initiation temperature. After step (iii), the polymer coating formed on the one or more surfaces of the reactor has a conformality of at least about 50% as measured by a wafer stacking method and/or a microscale conformality of at least about 60% as measured by a microgroove method.

In other examples, surface activated chemical vapor deposition (SACVD) can be performed under non-isothermal conditions. Under non-isothermal conditions, at least one substrate or device to be coated is placed in a reaction chamber. At least one substrate or device is placed on a temperature-controlled heating platform ("platform"), which can independently heat at least one substrate or device and surfaces in contact therewith. The platform is configured to support one or more substrates or devices in the reaction chamber during coating. The platform optionally retains and positions one or more substrates or devices in a desired position on the platform. In such methods, the reaction chamber is thermally controlled independently of the platform. The platform is heated to an initiation temperature sufficient to activate one or more gaseous initiators. In such non-isothermal methods, heating to the initiation temperature also heats one or more surfaces of a substrate or device within the reaction chamber to a temperature sufficient to decompose one or more initiators and thereby form/deposit a polymer coating on at least a portion of the one or more surfaces of the substrate or device. In such methods, the reaction chamber and/or its components are independently heated to a reaction chamber temperature that is below the initiation temperature and below the surface temperature. The reaction chamber components include the walls of the reaction chamber.

In one non-limiting example, a non-isothermal method comprises (i) placing the at least one substrate or device on a platform within a reaction chamber; (ii) sealing and purging the reaction chamber under vacuum; (iii) wherein the platform is at a triggering temperature sufficient to activate one or more gaseous initiators; wherein one or more surfaces of the at least one substrate or material have a surface temperature equal to or substantially equal to the triggering temperature; and (iv) flowing one or more gaseous monomers, the one or more gaseous initiators, and optionally one or more carrier gases into the reaction chamber to form the polymer coating on at least a portion of the one or more surfaces of the at least one substrate or device; wherein the reaction chamber and/or its components are independently heated to a reaction chamber temperature, wherein during step (iv) the reaction chamber temperature is below the initiation temperature and below the surface temperature; optionally wherein the components comprise a wall of the reaction chamber; wherein the partial pressure of the one or more gaseous monomers is sufficient to form the polymer coating on the portion of the one or more surfaces of the at least one substrate or device at the surface temperature.

In some cases, the temperature of the reaction chamber during step (iv) is sufficient to prevent one or more gaseous monomers or one or more gaseous initiators from exceeding their saturation pressure at the reaction chamber temperature.

In some cases, a polymer coating formed on one or more surfaces of at least one substrate or device has a conformality of at least about 50% as measured by a wafer stacking method; and/or wherein a polymer coating formed on one or more surfaces of at least one substrate or device has a microscale conformality of at least about 60% as measured by a microtrenching method.

During step (i), the platform and the reaction chamber and/or components thereof are independently temperature controlled. Prior to step (iv), one or more surfaces of at least one substrate or device have a surface temperature equal to or substantially equal to the initiation temperature. During step (iv), the reaction chamber and/or components thereof are independently heated to a reaction chamber temperature below the initiation temperature, optionally including the walls of the reaction chamber. During step (iv), the partial pressure of the one or more gaseous monomers is sufficient to cause the one or more gaseous monomers to adsorb on the at least one substrate or device at the surface temperature. In addition, the partial pressure of the one or more gaseous monomers is sufficient to form a polymer coating on a portion of the surface at the surface temperature.

The SACVD methods described herein can be used to deposit/form polymer coatings on surfaces of substrates or devices with a degree of conformality that is difficult to achieve using other deposition methods. In some cases, the substrate or device includes a polymer coating on at least one surface of the substrate or device. The polymer coating formed using the SACVD methods described herein: is conformal as determined by a wafer stacking method and has a step coverage of at least 50%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more; and/or has a microscale conformality of at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a microtrenching method.

In some cases, the coated device is (but not limited to) a microelectronic device, a microelectromechanical system (MEMS), microfluidics, a 3-D integrated heterogeneous package (IHP), a CMOS chip, a radio frequency (RF) device, a microchip, a board, a transistor, an ultra-high-speed mixed signal circuit, a power device, a switch, a clock reference, a frequency selective filter, a miniaturized array, a digital-to-analog converter, an analog-to-digital converter, and/or a low-noise amplifier or one or more substrates. The conformal polymer coating on the surface of such a device or its substrate can provide protection from environmental influences, mechanical protection, electrical insulation, electrical protection, and/or can impart optical effects, modify surface properties, and/or enhance biological or chemical compatibility.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Application No. 63/510,920, filed on June 29, 2023, which is incorporated herein by reference in its entirety.

The present invention generally describes a surface activated chemical vapor deposition method and its use for forming highly conformal coatings.

SACVD differs from conventional chemical vapor deposition (CVD) polymer coating methods because the formation of the active species is driven to the surface to selectively form a polymer coating thereon. Conventional CVD methods use energy input at a centralized location (i.e., hot filament CVD) or throughout the gas phase of the chamber (i.e., plasma-based CVD), neither of which is required in the methods described below. Instead, the substrate or device to be coated is itself heated to a temperature capable of activating the gaseous initiator species. When an initiator (e.g., a peroxide initiator) is activated at the heated surface, the initiator will cleave to form two free radicals, which can then initiate polymerization of gaseous monomer units adsorbed on the heated surface to specifically form a polymer coating thereon. This method allows polymer coatings to be formed without the need to diffuse activated monomer species away from activation sites, resulting in coatings with a significantly higher degree of conformality compared to coatings formed by conventional CVD.

I. Definitions As used herein, "initiation" refers to the action of a chemical species (such as a monomer) upon being acted upon by an initiator species (which may be generated by decomposition of a suitable initiator source) such that the chemical species is capable of forming a polymer coating on a surface. Initiator species may include, but are not limited to, ions and free radicals (such as diradicals) and combinations thereof.

As used herein, the term "reactive substance" refers to one or more substances that can be generated in the gas phase and form a polymer when polymerized. The term "reactive substance" includes monomers and/or oligomers. The reactive substances disclosed herein can be gaseous at room temperature and atmospheric pressure. Alternatively, the reactive substance is a liquid or solid at room temperature and atmospheric pressure, for example, it can be evaporated under reduced pressure or heated or both, in order to carry out the methods described herein.

As used herein, the terms "polymer" or "polymer coating" are used interchangeably and refer to a polymer that is generally composed of one or more monomers or "repeating units" that are chemically bonded together in some manner. It is understood that polymers formed including or formed from the monomers described herein may include other components. In addition, as will be understood by those skilled in the art, monomers are often chemically modified during the polymerization process, and therefore, one or more bonds present in the monomer may not be present in the polymer.

As used herein, "conformality" refers to the degree of uniformity of the thickness of a polymer coating deposited on a surface based on macroscale and/or microscale measurements. A conformal coating can be considered highly conformal when it has a conformality of at least about 50% as measured by wafer stacking methods.

As used herein, "microscale conformality" refers to the degree of uniformity of the thickness of a polymer coating deposited on a surface based on a micrometer-scale measurement, i.e., 10 micrometers or less. For example, a highly conformal coating can have a microscale conformality of at least about 60% as measured by the microgroove method.

As used herein, the term "gaseous polymerizable substance" refers to a reactive substance that can be generated in the gas phase and forms a polymer when polymerized. The term "gaseous polymerizable substance" includes monomers, oligomers, and metal organic compounds. The gaseous polymerizable substances disclosed herein may not necessarily be gases at room temperature and atmospheric pressure. For example, if such substances are liquids or solids, they can be evaporated under reduced pressure or heated, or both, in order to carry out the methods described herein.

"Inert gas" or "inert atmosphere" are used interchangeably herein and refer to a gas or gas mixture that is non-reactive under the reaction conditions within the vacuum chamber.

The numerical ranges disclosed in this application include, but are not limited to, temperature ranges, pressure ranges, molecular weight ranges, integer ranges, force ranges, time ranges, thickness ranges, and gas flow rate ranges. Any type of disclosed range individually discloses every possible number that such range can reasonably cover, as well as any subranges and combinations of subranges covered therein. For example, the disclosure of a temperature range is intended to individually disclose that such range can cover every possible temperature value consistent with the disclosure herein. In another example, the present invention states that conformality (expressed as a percentage) can be in the range of about 50% to about 90%, which also means that the percentage values can be independently selected from about 57%, 68% and 79%, and any sub-ranges between these values (e.g., about 65% to 85%), and any possible combination of ranges between these values.

II. Surface Activated Chemical Vapor Deposition ( SACVD ) In general, SACVD processes work by heat-assisted formation of chemically reactive species (such as initiator radicals) directly on one or more surfaces coated in situ with the polymer to be used. Due to the direct formation of such species on the surface of the substrate or device, the diffusion lengths of the reactive species are significantly reduced, thereby providing a beneficial effect on the conformality that can be obtained using SACVD methods. In contrast, initiated chemical vapor deposition (iCVD) processes use a filament to thermally decompose chemicals (such as free radical initiators) at the filament, which chemicals need to diffuse into the substrate or device in addition to penetrating any geometrical complexity that may be present therein. Due to their reactive nature, these free radical species also exhibit relatively high adhesion coefficients and exhibit a greater likelihood of adhering to surfaces other than the surface intended to be coated, encountering and not desorbing and continuing to diffuse toward the substrate or device, as well as penetrating geometrically complex substrates or devices. When such species are desired to diffuse from a remote filament, the result is a degree of preferential deposition within the line of sight of the filament. In contrast, SACVD is expected to produce reactive species such as free radical species directly on areas of one or more surfaces of the substrate or device intended to be coated, which significantly alleviates the diffusion barrier problem used to produce polymer coating thicknesses with a high degree of uniformity and conformality. Various methods of SACVD are described below.

The SACVD methods described herein can be used to deposit one or more polymer coatings on a substrate or device. Certain substrates or devices, such as microelectronic device stacks, boards, electronic device components, and 3-D integrated heterogeneous packages can have one or more relatively high aspect features thereon and can form highly conformal coatings thereon using the SACVD methods described herein.

The conformality of a polymer coating can be evaluated, for example, by depositing a given polymer coating on a wafer stack, as shown in FIGS. 1A-1B . The wafer stack can include a top wafer 110 and a bottom wafer 120 separated by two side tapes 130 a, 130 b, which create a channel feature 150 for evaluating the conformality of the polymer coating deposited therein. An adhesive 140 (such as a tape) holds the silicon wafer stack together. The thickness of the polymer coating formed in the channel feature 150 of the wafer stack can be analyzed and the thickness of the coating at the opening 152 of the channel feature to the thinnest portion of the coating within the channel feature is measured. The different thicknesses of the polymer coating can be measured by reflectometry or any other suitable method known in the art for measuring coating thickness. In the reference wafer stack, the wafer stack has the dimensions listed in Table 1 below: Table 1. Exemplary wafer stack dimensions Components Length(mm) Width(mm) Height(mm) 110/120 25 25 0.5 130a/130b 25 4 0.5

To express conformality as a percentage using the wafer stacking method, the following equation can be used: The higher the percentage, the higher the degree of conformality. Based on an exemplary wafer stack with the dimensions given in Table 1, the thinnest coating is typically measured at the center of the bottom wafer 120 or the top wafer 110, which is approximately 12.5 mm from the entrance of the wafer stack.

Using the wafer stack method, the conformality of coatings formed by different methods of depositing polymer coatings using the same conditions (i.e., monomer, initiator, carrier gas composition) can be compared. In some cases, polymer coatings produced by SACVD have a conformality of at least about 40%, or a conformality in the range of about 40% to about 90% or more, as determined using the wafer stack method, when tested using a wafer stack having the dimensions of the reference wafer stack described above. In some cases, the conformality is at least about 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, or 99.9% as measured by the wafer stacking method when tested using a wafer stack having the dimensions of the reference wafer stack described above.

The microscale conformality of a polymer coating can be evaluated, for example, by depositing a given polymer coating in a microgrooved substrate. A non-limiting example of a microgrooved substrate 200 is shown in FIG. 1C . The thickness of the polymer coating formed within the microgrooves 210 can be analyzed, wherein the different thicknesses of the polymer coating on the sidewalls (230a/230b) and the bottom (220) can be determined by electron microscopy or any other suitable method known in the art for measuring coating thickness. In the reference microgrooves, as detailed in Table 2 below, the microgrooves have the following dimensions: Table 2. Exemplary Microgrooves Dimensions Components Length(µm) Each side wall 57 bottom 4.5

To express microscale conformality as a percentage using the microtrench method, the following equation can be used: The higher the percentage value, the higher the degree of microscale conformality.

Using the microtrench method, the microscale conformality of coatings formed by different methods of depositing polymer coatings using the same conditions (i.e., monomer, initiator, carrier gas composition) can be compared. In some cases, polymer coatings produced by SACVD have a microscale conformality of at least about 50%, or a conformality in the range of about 50% to about 90% or more, as determined using the microtrench method, when tested using microtrench having the dimensions of the reference microtrench described above. In some cases, the microscale conformality is at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, or 99.9% as measured by the Microtrench Method when tested using the Microtrench Method having the dimensions of the reference microtrench described above.

The microtrench method can be used to determine the microscale conformality of polymer coatings after coating devices and/or surfaces containing complex and/or high aspect ratio features such as those found in 3-D integrated heterogeneous packages (HIPs), microelectronic device stacks, microelectronic device boards, or electronic device assemblies.

A. Isothermal Surface Activated Chemical Vapor Deposition In the first instance, surface activated chemical vapor deposition (SACVD) can be performed under isothermal conditions. Under isothermal conditions, at least one substrate or device to be coated with a polymer coating (or polymer film) is placed in a reaction chamber, and the reaction chamber is heated to an initiation temperature sufficient to activate one or more gaseous initiators. In such methods, heating to the initiation temperature also heats one or more surfaces of the substrate or device in the reaction chamber to allow decomposition of the one or more initiators and formation/deposition of the polymer coating on at least a portion of the one or more surfaces of the substrate or device. Use of an isothermal process allows SACVD formation of coatings on all surfaces within a reaction chamber that have a surface temperature equal to or substantially equal to the initiation temperature without regard to thermal contact with a substrate or device stage or platform. This can be advantageous when it is desired to form a polymer coating on all sides of a substrate or device, or when it is desired to form a polymer coating on a large number of components of such a substrate or device, such as when closely spaced. In contrast, isothermal CVD processes do not produce the same high degree of conformality in the coatings formed because other surfaces within the CVD reaction chamber, such as the chamber walls, are also at a sufficiently high temperature to initiate the gaseous initiator species therein. These activated initiator species can then diffuse into the substrate or device to be coated, resulting in additional line-of-sight coating and reducing the overall conformality ratio of the final polymer coating formed on the substrate or device. Such loss of conformality can be minimized by increasing the distance between the surface within the deposition chamber and the substrate or device to be coated.

A non-limiting first example of an isothermal SACVD method may include the following steps: (i) placing the at least one substrate or device into a reaction chamber; (ii) sealing and purging the reaction chamber under vacuum; (iii) wherein the reaction chamber is at an initiation temperature sufficient to activate one or more gaseous initiators; wherein one or more surfaces of the at least one substrate or material have a surface temperature equal to or substantially equal to the initiation temperature to which the reaction chamber is heated; and (iv) flowing one or more gaseous monomers, the one or more gaseous initiators, and optionally one or more carrier gases into the reaction chamber to form the polymer coating on at least a portion of the one or more surfaces of the at least one substrate or device; wherein the partial pressure of the one or more gaseous monomers is sufficient to form the polymer coating on the portion of the one or more surfaces of the at least one substrate or device at the surface temperature.

In some embodiments, the surface temperature during step (iv) is sufficient to prevent the one or more gaseous monomers or the one or more gaseous initiators from exceeding their saturation pressure at the surface temperature.

In some cases, a polymer coating formed on one or more surfaces of at least one substrate or device has a conformality of at least about 40% as measured by a wafer stacking method; and/or wherein a polymer coating formed on one or more surfaces of at least one substrate or device has a microscale conformality of at least about 50% as measured by a microtrenching method.

Prior to step (iv), the one or more surfaces of the at least one substrate or device has a temperature equal to or substantially equal to the initiation temperature. During step (iv), the partial pressure of the one or more gaseous monomers is sufficient to cause the one or more gaseous monomers to adsorb on the one or more surfaces of the at least one substrate or device at the surface temperature. Additionally, the partial pressure of the one or more gaseous monomers is sufficient to form a polymer coating on the portion on the surface at the surface temperature.

In some examples of the above methods, at least one substrate or device is a plurality of substrates and/or devices, and each of the plurality of substrates and/or devices is independently placed on a separate temperature-controlled platform.

In an alternative to the above isothermal method, the substrate to be coated can itself serve as the reaction chamber or reactor. In such instances, the reactor and one or more surfaces of the reactor to be coated with the polymer coating (or polymer film) are heated to an initiation temperature sufficient to activate one or more gaseous initiators. Heating the reactor to the initiation temperature allows the one or more initiators to decompose and form/deposit the polymer coating on at least a portion of one or more surfaces of the reactor.

A non-limiting second example of an isothermal SACVD method may include the following steps: (i) sealing and purging a reactor under vacuum; (ii) wherein the reaction chamber is at an initiation temperature sufficient to activate one or more gaseous initiators; and (iii) introducing one or more gaseous monomers, one or more gaseous initiators, and optionally one or more carrier gases into the reactor to form a polymer coating on at least a portion of the one or more surfaces of the reactor.

Prior to step (iii), one or more surfaces of the reactor have a surface temperature equal to or substantially equal to the initiation temperature. After step (iii), the polymer coating formed on the one or more surfaces of the reactor has a conformality of at least about 50% as measured by a wafer stacking method and/or a microscale conformality of at least about 60% as measured by a microgroove method.

For the isothermal methods described herein, there may be a period of time between step (i) and step (iii) and until step (iv), which is a dwell time, during which the temperature of the substrate surface is raised to the surface temperature, and wherein the dwell time is at least about 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 minutes. Heating may be performed for any suitable period of time during the dwell time that is sufficient to bring one or more surfaces of the substrate or device in the first method or one or more surfaces of the reactor in the second method to equal or substantially equal to the selected initiation temperature. As used herein, "substantially equal to" with respect to an initiation temperature refers to a surface temperature that is about ±10%, ±9%, ±8%, ±7%, ±6%, ±5%, ±4%, ±3%, ±2%, or ±1% of a selected initiation temperature. In some examples, heating may be applied for at least about 1 to 90 minutes, or any subrange or individual minute value disclosed, to allow one or more surfaces of a substrate or device to reach the desired initiation temperature.

The flow step can be performed for any suitable time period sufficient to form/deposit a polymer film having one or more desired properties (e.g., thickness). In some examples, the flow step can be performed for at least about 1 to 800 minutes or 30 to 800 minutes, and any sub-ranges or individual minute values disclosed within these ranges.

In some cases, after the polymer coating is formed/deposited during the mobilization step, the reaction chamber or reactor of the above method is purged and cooled to room temperature (about 25° C.), and then the reaction chamber or reactor is vented.

Each of the gaseous monomer, gaseous initiator, and optionally the carrier gas can flow continuously or discontinuously during the flow step of the isothermal method. In certain embodiments, the polymer coating is formed continuously or semi-continuously during the flow step, depending on the selected parameters for controlling the flow of the monomer and initiator during the step. In instances where the flow of any of the gaseous monomer, gaseous initiator, and optionally, carrier gas is discontinuous during a flow step, these may be independently controlled by flow controllers and metering valves, wherein the flow time, stop time, number of on/off cycles, and other parameters (such as pressure) during the flow step of each gaseous component may be independently selected as needed to produce the desired polymer coating.

For the described isothermal method, the mobilization step can be repeated more than once with the same or different compositions of gaseous monomer, gaseous initiator and, if applicable, carrier gas. When different monomers are used in the repeated mobilization steps, the polymer coating comprises a plurality of polymer layers. Thus, in some instances where the polymer coating is formed of more than one layer, the polymer coating comprises at least one layer formed of a polymer different from the polymer forming another layer/different layer.

In some cases, the polymer coating formed by flowing at least two different types of gaseous monomers during the flowing step contains one or more polymers, copolymers and/or one or more crosslinked polymers, and when forming a crosslinked polymer, one or more gaseous crosslinking agents are optionally flowed during the same step.

In some cases, the initiation temperature is selected to provide a polymer deposition rate of at least 0.5 nm/min to form the polymer coating.

In certain instances, the conditions within the reaction chamber/reactor are selected to provide a polymer coating that is free of defects or substantially free of defects. To provide a polymer coating that is free of defects or substantially free of defects, the conditions within the reaction chamber/reactor are selected to prevent the formation of defects in the polymer coating at least during formation, wherein the defects may include bubbles, blistering, pinholes, cracks, or particles. As used herein, "substantially free of defects" refers to the presence of a low number of defects in the polymer coating, wherein at least 95%, 96%, 97%, 98%, 99% or more of the polymer coating is free of defects as determined by suitable visualization means, such as scanning electron microscopy (SEM). In some cases, defects can be avoided when the partial pressure of any single gaseous component does not exceed its saturation pressure on the substrate or device to be coated. If any gaseous component exceeds the saturation pressure, liquid films of the individual components may form on a given surface, and bubbles may be generated if initiation occurs at the surface. In addition, the presence of a liquid film anywhere in the CVD chamber may lead to the formation of particles, which may diffuse throughout the chamber and may produce coating defects. Therefore, the SACVD deposition method should avoid conditions that allow deposition on the liquid surface, so that the thermodynamics of the SACVD process should be controlled to prevent any conditions that lead to the formation of undesirable liquid during the deposition process. As a non-limiting example, the example of a process using a single monomer, initiator, and carrier gas is discussed below. To avoid defects such as blistering, _the SACVD deposition of the described method is operated so that the following conditions are met _{simultaneously: Pmonomer < Pmonomer saturated} Pinitiator < _Pinitiator saturated _{Pcarrier <} Pcarrier saturated _where the partial pressure is related to the total pressure and flow rate by the following relationship:

Therefore, the saturation pressure of each gaseous component can be estimated using a number of methods known in the art. Process conditions can be selected that allow coating deposition while avoiding saturation. For example, parameters that can be controlled include: chamber temperature, total pressure, partial pressures of individual gaseous species, gas residence time, precursor (if liquid) temperature, thermal resistance of the substrate or device to the desired initiation temperature, and/or spacing of substrate or device components within the chamber. The criteria may be selected to avoid reduced levels of conformality of the polymer coating results due to diffusion of reactive monomer species away from heated surfaces of the substrate or device to be coated, condensation of reactants (i.e., gaseous monomers and/or initiators), failure to achieve desired reactant ratios due to high chamber pressures, deposition rates that are insufficient to effectively form a conformal polymer coating due to, for example, low chamber pressures or high surface temperatures, and/or lack of polymer coating uniformity due to consumption of reactants prior to encountering at least a portion of the substrate surface to be coated.

In some cases, one or more surfaces of the substrate or device in the first method or one or more surfaces of the reactor in the second method may be treated prior to the first step, wherein the treatment is silane deposition, electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure, or a combination thereof. In some cases, the treatment is applied after forming/depositing the polymer coating, such as electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure, or a combination thereof.

B. Non-Isothermal Surface Activated Chemical Vapor Deposition In a second example, surface activated chemical vapor deposition (SACVD) can be performed under non-isothermal conditions. Under non-isothermal conditions, at least one substrate or device to be coated with a polymer coating (or polymer film) is placed in a reaction chamber. At least one substrate or device is placed on a temperature-controlled heating platform ("platform") that can independently heat at least one substrate or device and a surface present thereon. The platform is configured to support one or more substrates or devices in the reaction chamber during coating and can independently heat one or more substrates or devices in contact therewith. The platform optionally retains and positions one or more substrates or devices. In this type of method, the reaction chamber is thermally controlled independently of the platform. The platform is heated to an initiation temperature sufficient to activate the one or more gaseous initiators. In such non-isothermal methods, heating to the initiation temperature also heats one or more surfaces of a substrate or device within the reaction chamber to allow decomposition of the one or more initiators and formation/deposition of a polymer coating on at least a portion of the one or more surfaces of the substrate or device. In such methods, the reaction chamber and/or its components are independently heated to a temperature below the initiation temperature, referred to herein as the reaction chamber temperature. To the extent that the temperature of the reaction chamber and/or its components varies, the reaction chamber temperature refers to its lowest temperature. The reaction chamber components include the walls of the reaction chamber.

As described above, non-isothermal SACVD differs from isothermal SACVD in that it can be used to minimize the activation of reactive initiators and/or monomeric species at sites remote from the surface of the substrate or device to be coated. Thus, using a non-isothermal SACVD method, the chance of such activated species undesirably diffusing reactive species away from the substrate or device surface, thereby resulting in a non-conformal site-line coating on the surface, can be minimized or eliminated. In addition to the parameters selected to control the isothermal SACVD process (described in detail above), non-isothermal SACVD also includes additional parameters selected to provide the desired process conditions for forming a conformal coating on a substrate or device. Since portions of the reaction chamber are at a lower temperature than the substrate or device (which is on a heated platform), non-isothermal SACVD can have a greater risk of precursor (i.e., monomer) condensation and requires thermal control of the substrate or device to provide uniform heating thereof, such as in the case of an insulated substrate. Parameters can be selected to minimize or eliminate any undesirable non-uniform heating, which can result in polymer coating growth rate deviations and loss of a high degree of coating conformality.

Non-limiting examples of non-isothermal methods include the following steps: (i) placing the at least one substrate or device on a platform within a reaction chamber; (ii) sealing and purging the reaction chamber under vacuum; (iii) wherein the platform is at a triggering temperature sufficient to activate one or more gaseous initiators; wherein one or more surfaces of the at least one substrate or material have a surface temperature equal to or substantially equal to the triggering temperature; and (iv) flowing one or more gaseous monomers, the one or more gaseous initiators, and optionally one or more carrier gases into the reaction chamber to form the polymer coating on at least a portion of the one or more surfaces of the at least one substrate or device; wherein the reaction chamber and/or its components are independently heated to a reaction chamber temperature which is below the initiation temperature and below the surface temperature during step (iv); optionally wherein the components comprise a wall of the reaction chamber; wherein the partial pressure of the one or more gaseous monomers is sufficient to form the polymer coating on the portion of the one or more surfaces of the at least one substrate or device at the surface temperature. In some cases, the reaction chamber temperature during step (iv) is sufficient to prevent the one or more gaseous monomers or one or more gaseous initiators from exceeding their saturation pressure at the reaction chamber temperature.

In some cases, a polymer coating formed on one or more surfaces of at least one substrate or device has a conformality of at least about 40% as measured by a wafer stacking method; and/or wherein a polymer coating formed on one or more surfaces of at least one substrate or device has a microscale conformality of at least about 50% as measured by a microtrenching method.

During step (i), the platform and the reaction chamber and/or components thereof are independently temperature controlled. Prior to step (iv), one or more surfaces of at least one substrate or device have a surface temperature equal to or substantially equal to the initiation temperature. During step (iv), the reaction chamber and/or components thereof are independently heated to a reaction chamber temperature below the initiation temperature, optionally wherein the components include walls of the reaction chamber. During step (iv), the partial pressure of the one or more gaseous monomers is sufficient to cause the one or more gaseous monomers to adsorb on the at least one substrate or device at the surface temperature. In addition, the partial pressure of the one or more gaseous monomers is sufficient to form a polymer coating on a portion of the surface at the surface temperature.

In some examples of the above methods, at least one substrate or device is a plurality of substrates and/or devices, and each of the plurality of substrates and/or devices may be independently placed on a separate temperature-controlled platform as appropriate.

For the non-isothermal methods described herein, the temperature to which the reaction chamber (and/or reaction chamber temperature) and/or its components are independently heated can be selected to prevent the partial pressures of one or more gaseous monomers and one or more gaseous initiators from exceeding their corresponding saturation pressures at the selected temperature.

In some cases, there may be a period of time between step (i) and step (iii) and until step (iv), which is a dwell time during which the temperature of the substrate surface is increased to the surface temperature, and wherein the dwell time is at least about 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 minutes. Heating can be performed for any suitable period of time during the dwell time that is sufficient to make one or more surfaces of the substrate or device equal to or substantially equal to the selected triggering temperature. In some cases, heating is performed for at least about 1 to 60 minutes, or any subrange or individual minute value disclosed herein.

The flow step can be performed for any suitable time period sufficient to form/deposit a polymer film having one or more desired properties (e.g., thickness). In some examples, the flow step is performed for at least about 1 to 800 minutes or 30 to 800 minutes, and any sub-ranges or individual minute values disclosed within these ranges.

In some cases, after the polymer coating is formed/deposited during the mobilization step, the reaction chamber is purged and allowed to cool to room temperature (about 25° C.), and then the reaction chamber is vented.

Each of the gaseous monomer, gaseous initiator, and optionally the carrier gas can flow continuously or discontinuously during the flow step of the non-isothermal method. In certain embodiments, the polymer coating is formed continuously or semi-continuously during the flow step, depending on the selected parameters for controlling the flow of the monomer and initiator during the step. In instances where the flow of any of the gaseous monomer, gaseous initiator, and optionally, carrier gas is discontinuous during a flow step, these may be independently controlled by flow controllers and metering valves, wherein the flow time, stop time, number of on/off cycles, and other parameters (such as pressure) during the flow step of each gaseous component may be independently selected as needed to produce the desired polymer coating.

For the described non-isothermal methods, the mobilization step can be repeated more than once with the same or different compositions of gaseous monomer, gaseous initiator and, if applicable, carrier gas. When different monomers are used in the repeated mobilization steps, the polymer coating comprises a plurality of polymer layers. Thus, in some instances where the polymer coating is formed of more than one layer, the polymer coating comprises at least one layer formed of a polymer different from the polymer forming another layer/a different layer.

In some cases, the polymer coating formed by flowing at least two different types of gaseous monomers during the flowing step contains one or more polymers, copolymers and/or one or more crosslinked polymers, and when forming a crosslinked polymer, one or more gaseous crosslinking agents are optionally flowed during the same step.

In some cases, the initiation temperature is selected to provide a deposition rate of polymer of at least 0.5 nm/min to form the polymer coating. Optionally, the initiation temperature may be selected to be sufficiently low to prevent the formation of defects in the polymer coating at least during the formation period, wherein the defects may include bubbles, blistering, pinholes, cracks. In some cases, the polymer coating formed is defect-free or substantially defect-free.

In some cases, one or more surfaces of the substrate or device may be treated prior to the first step, wherein the treatment is silane deposition, electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure, or a combination thereof. In some cases, after forming/depositing the polymer coating, a treatment such as electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure, or a combination thereof may be applied.

C. General SACVD Parameters For the SACVD methods described in Sections II.A and II.B above, the following parameters are generally applicable to the methods described herein.

The SACVD methods described may not include the use of hot filament heating, resistive heating, induction heating, radiation heating, electron beam, laser exposure, radio frequency (RF), microwave excitation, ultraviolet (UV), infrared (IR) radiation, and/or gamma radiation to initiate or cause decomposition of one or more gaseous initiators or gaseous monomers.

a. Gaseous Monomers Polymer coatings can be formed using a variety of different gaseous monomers that, when initiated by suitable free radical or ionic species, form gaseous polymerizable species and are deposited to form a polymer coating on a surface.

In some cases, for the SACVD method described above, the polymer coating is formed by vinyl polymerization, wherein the one or more gaseous monomers include a monomer having at least one vinyl moiety thereon. In some cases, the vinyl polymerization is a free radical vinyl polymerization.

Without particular limitation, the one or more gaseous monomers may be (n-)acrylate monomers, methacrylate monomers, vinyl-containing monomers, parylene monomers, ethylene oxide-based monomers, or combinations thereof.

In some cases, the acrylate monomer is hydroxyethyl acrylate, ethylene glycol diacrylate, 1H,1H,2H,2H-perfluorodecyl acrylate, or a combination thereof. In some cases, the methacrylate monomer is hydroxyethyl methacrylate, ethylene glycol dimethacrylate, 1H,1H,2H,2H-perfluorodecyl methacrylate, or a combination thereof.

In some embodiments, the vinyl-containing monomer is 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, divinylbenzene, 4-vinylpyridine, styrene, 1H,1H,2H-perfluoro-1-dodecene, di(ethylene glycol) divinyl ether, or a combination thereof.

In some embodiments, the parylene monomer is [2,2] parylene, dichloro-[2,2]-parylene, 1,1,2,2,9,9,10,10-octafluoro[2.2]parylene, or 4,5,7,8,12,13,15,16-octafluoro[2.2]parylene.

In some embodiments, the ethylene oxide-based monomer is hexafluoropropylene oxide.

b. Gaseous Initiators Polymer coatings can be formed using a variety of different gaseous initiators that can thermally decompose to produce reactive species that initiate polymerization of the gaseous monomers.

In some cases, the gaseous initiator may include one or more groups capable of generating free radicals under experimental conditions. Such free radicals may react with monomers to form growing polymer chains. The initiator can be thermally decomposed to form one or more molecules with free radicals. In some cases, the initiator may include a functional group capable of forming free radicals under experimental conditions (e.g., by decomposition). Non-limiting examples of suitable functional groups include peroxide groups, persulfate groups, and azo groups. In other examples, the initiator may include one or more groups capable of generating ions under experimental conditions.

For gaseous initiators, the SACVD method involves selecting an appropriate initiation temperature based on the specific initiator used in a given deposition. The initiation temperature is the temperature at which a sufficient amount of the gaseous initiator decomposes and is capable of initiating free radical or ionic polymerization of gaseous monomers present, for example, during the flow step of the described SACVD method. In some examples, the initiation temperature can be in the range of about 50° C. to about 400° C., and sub-ranges or individual temperature values disclosed herein. In some other examples, the initiation temperature is in the range of about 100° C. to about 250° C., and sub-ranges or individual temperature values disclosed herein.

In some examples of SACVD methods, the one or more gaseous initiators include at least one free radical thermal initiator and/or at least one ionic (ie, cation or anion) thermal initiator, more preferably at least one free radical thermal initiator.

In certain examples, the free radical thermal initiator can be a peroxide-based initiator, a poly(p-xylene)-based initiator, an ethylene oxide-based initiator, or a combination thereof.

In some cases, the peroxide-based gaseous initiator is hydrogen peroxide, an alkyl peroxide or an aryl peroxide (e.g., tertiary butyl peroxide), a hydroperoxide, or a combination thereof. In still other cases, the peroxide-based gaseous initiator is tertiary butyl hydroperoxide, isopropylbenzene hydroperoxide, di-tertiary butyl peroxide, diisopropylbenzene peroxide, benzoyl peroxide, ammonium persulfate, or a combination thereof. In still other cases, at least one free radical thermal initiator may be an azonitrile-based initiator, wherein the azonitrile-based initiator may be azobisisobutylonitrile, 2,2'-azobis[2-(2-imidazolin-2-yl)-propane] dihydrochloride, or a combination thereof.

In some embodiments, the gaseous ion thermal initiator is dicyandiamide, cyclohexyl toluenesulfonate, (4-hydroxyphenyl)-dimethylcorbyl hexafluorophosphate, diphenyl(methyl)corbyl tetrafluoroborate, benzyl(4-hydroxyphenyl)-methylcorbyl hexafluoroantibonate, (4-hydroxyphenyl)methyl-(2-methylbenzyl)corbyl hexafluoroantibonate, triphenylcorbyl nonafluorobutanesulfonate, or a combination thereof.

In other embodiments, the gaseous initiator can be selected from compounds of formula I: A-X-B (Formula I) wherein, at each occurrence, A is independently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, aralkyl or heteroaralkyl; X is -O-O- or -N=N-; and B is hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, aralkyl or heteroaralkyl.

In certain embodiments, the initiator is a compound of Formula I, wherein A is alkyl.

In certain embodiments, the initiator is a compound of Formula I, wherein A is hydrogen.

In certain embodiments, the initiator is a compound of Formula I, wherein B is alkyl.

In certain embodiments, the initiator is a compound of Formula I, wherein X is -O-O-.

In certain embodiments, the initiator is a compound of Formula I, wherein X is -N=N-.

In some cases, the initiator is a compound of formula I, wherein A is -C(CH ₃ ) ₃ ; and B is -C(CH ₃ ) ₃ . In some cases, the gaseous initiator of the present invention is a compound of formula I, wherein A is -C(CH ₃ ) ₃ ; X is -OO-; and B is -C(CH ₃ ) ₃ .

The initiators described above can be in gaseous form. It should be noted that "gaseous" initiators cover initiators that can be liquid or solid at standard temperature and pressure (STP), but can vaporize and flow into the reaction chamber after heating.

c. SACVD Reactant Pressure and Optional Carrier Gas For the SACVD methods described herein, the polymer coating can be formed in the reaction chamber or reactor at any suitable total pressure. In some examples, the total pressure of all gaseous components during the flowing step ranges from about 1 to 760,000 mTorr. The partial pressure is selected to prevent condensation of any reactant species at all surface temperatures present in the reaction chamber, while maximizing adsorption of such species to allow polymerization reactions and polymer coating growth to proceed.

In some other instances, the total pressure of all gaseous components during the flowing step ranges from about 100 mTorr to 10 Torr. In still other instances, the total pressure of all gaseous components (e.g., monomers, initiators, inert gases) present during polymerization in the flowing step of the method can fall within the specified range. In some cases, the total pressure of all gaseous components present during polymerization is greater than or equal to 10 mTorr, greater than or equal to 25 mTorr, greater than or equal to 50 mTorr, greater than or equal to 75 mTorr, greater than or equal to 100 mTorr, greater than or equal to 200 mTorr, greater than or equal to 200 mTorr, greater than or equal to 300 mTorr, greater than or equal to 400 mTorr, greater than or equal to 500 mTorr, greater than or equal to 750 mTorr, greater than or equal to 1000 mTorr, or greater than or equal to 2500 mTorr. In certain embodiments, the total pressure of all gaseous components present during polymerization is less than or equal to 5000 mTorr, less than or equal to 2500 mTorr, less than or equal to 1000 mTorr, less than or equal to 750 mTorr, less than or equal to 500 mTorr, less than or equal to 400 mTorr, less than or equal to 300 mTorr, less than or equal to 200 mTorr, less than or equal to 100 mTorr, less than or equal to 75 mTorr, less than or equal to 50 mTorr, or less than or equal to 25 mTorr. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 50 mTorr and less than or equal to 5000 mTorr, greater than or equal to 50 mTorr and less than or equal to 300 mTorr, greater than or equal to 50 mTorr and less than or equal to 200 mTorr, greater than or equal to 75 mTorr and less than or equal to 200 mTorr, or greater than or equal to 75 mTorr and less than or equal to 100 mTorr). In some embodiments, the total pressure of all gaseous components present during polymerization can be atmospheric pressure.

The polymerization occurs under conditions including the presence of one or more gaseous monomers, which may be present at any suitable partial pressure. In some cases, the partial pressure of any of the one or more monomers may be less than or equal to 300 mTorr, 200 mTorr, 100 mTorr, 75 mTorr, less than or equal to 50 mTorr, less than or equal to 30 mTorr, less than or equal to 20 mTorr, less than or equal to 15 mTorr, less than or equal to 10 mTorr, less than or equal to 5 mTorr, or less than or equal to 3 mTorr. In some cases, the partial pressure is less than 50 mTorr. In some cases, the partial pressure is about 5 mTorr. In some cases, the partial pressure of any one or more monomers may be greater than or equal to 1 mTorr, greater than or equal to 5 mTorr, greater than or equal to 10 mTorr, or greater than or equal to 20 mTorr. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 3 mTorr and less than or equal to 50 mTorr, greater than or equal to 1 mTorr and less than or equal to 50 mTorr, greater than or equal to 1 mTorr and less than or equal to 20 mTorr, greater than or equal to 3 mTorr and less than or equal to 10 mTorr).

The polymerization of one or more monomers is carried out in the presence of one or more gaseous initiators. Gaseous initiators containing free radical generating groups or capable of reacting to form free radical species are preferred. The gaseous initiator can be present at any suitable partial pressure. In some embodiments, the partial pressure of the initiator can be less than or equal to 300 mTorr, 200 mTorr, 100 mTorr, 75 mTorr, less than or equal to 50 mTorr, less than or equal to 30 mTorr, less than or equal to 20 mTorr, less than or equal to 15 mTorr, less than or equal to 10 mTorr, less than or equal to 5 mTorr or less than or equal to 3 mTorr. In some cases, the partial pressure of the gaseous initiator may be greater than or equal to 1 mTorr, greater than or equal to 5 mTorr, greater than or equal to 10 mTorr, or greater than or equal to 20 mTorr. In some embodiments, the partial pressure of the monomer is less than about 75 mTorr. In some embodiments, the partial pressure of the initiator is about 7.5 mTorr. Combinations of the ranges referenced above are also possible (e.g., greater than or equal to 1 mTorr and less than or equal to 75 mTorr, or greater than or equal to 1 mTorr and less than or equal to 50 mTorr, greater than or equal to 1 mTorr and less than or equal to 20 mTorr, greater than or equal to 1 mTorr and less than or equal to 10 mTorr, greater than or equal to 5 mTorr and less than or equal to 10 mTorr).

The one or more gaseous monomers and the one or more gaseous initiators can be provided in any suitable ratio. In some examples, the ratio can be based on the partial pressures of the one or more gaseous monomers and the one or more gaseous initiators present during the flow step of the described SACVD method. The ratio of the partial pressure of the one or more gaseous initiators to the partial pressure of the one or more gaseous monomers (defined as the partial pressure of the one or more gaseous initiators divided by the partial pressure of the one or more gaseous monomers present) can be any suitable value. In some cases, the ratio of the initiator partial pressure to the monomer partial pressure may be greater than or equal to 0.1, greater than or equal to 0.2, greater than or equal to 0.5, greater than or equal to 0.8, greater than or equal to 1, greater than or equal to 2, greater than or equal to 5, or greater than or equal to 8. In some cases, the ratio of the partial pressure of one or more gaseous initiators to the partial pressure of one or more gaseous monomers may be less than or equal to 10, less than or equal to 8, less than or equal to 5, less than or equal to 2, less than or equal to 1, less than or equal to 0.8, less than or equal to 0.5, or less than or equal to 0.2. Combinations of the above-mentioned ranges are also possible (e.g., greater than or equal to 0.1 and less than or equal to 10).

In some cases (e.g., during deposition of a polymer coating), a reaction chamber or reactor may include a relatively large amount of monomer and/or monomer precursor. In some cases, the monomer and/or monomer precursor comprises greater than or equal to 1 mol%, greater than or equal to 2 mol%, greater than or equal to 5 mol%, greater than or equal to 7.5 mol%, greater than or equal to 10 mol%, greater than or equal to 15 mol%, greater than or equal to 20 mol%, greater than or equal to 30 mol%, greater than or equal to 40 mol%, greater than or equal to 50 mol%, or greater than or equal to 75 mol% of the gas in the reaction volume. In some examples, the monomer and/or monomer pre-driver accounts for less than or equal to 100 mol%, less than or equal to 75 mol%, less than or equal to 50 mol%, less than or equal to 40 mol%, less than or equal to 30 mol%, less than or equal to 20 mol%, less than or equal to 15 mol%, less than or equal to 10 mol%, less than or equal to 7.5 mol%, less than or equal to 5 mol%, or less than or equal to 2 mol% of the gas in the reaction volume. Combinations of the above-mentioned ranges are also possible (e.g., greater than or equal to 1 mol% and less than or equal to 100 mol%).

Polymerization may occur in the presence of one or more inert gases that do not participate in the polymerization process, as appropriate. In some instances, such gases may be referred to as carrier gases. Carrier gases are typically inert gases. In some instances, one type of inert gas, two types of inert gases, three types of inert gases, or more may be present during polymerization in the flow step of the SACVD method. Non-limiting examples of inert gases include nitrogen, helium, and argon. The inert gas may account for any suitable percentage of the total pressure during polymerization. The total pressure during polymerization may be defined as the sum of the partial pressures of the gaseous monomers, gaseous initiators, and inert gases present during polymerization. In some cases, the inert gas accounts for greater than or equal to 50% of the total pressure, greater than or equal to 60% of the total pressure, greater than or equal to 70% of the total pressure, greater than or equal to 80% of the total pressure, greater than or equal to 90% of the total pressure, or greater than or equal to 95% of the total pressure. In certain embodiments, the inert gas accounts for less than or equal to 98% of the total pressure, less than or equal to 95% of the total pressure, less than or equal to 90% of the total pressure, less than or equal to 80% of the total pressure, less than or equal to 70% of the total pressure, or less than or equal to 60% of the total pressure. Combinations of the above-mentioned ranges are also possible (for example, greater than or equal to 50% and less than or equal to 90% of the total pressure, greater than or equal to 70% and less than or equal to 90% of the total pressure, or greater than or equal to 80% and less than or equal to 90% of the total pressure).

One or more monomers, initiators, and optionally a carrier or inert gas are typically flowed into a reaction chamber or reactor to produce polymerization of the monomers and to deposit a polymer coating on one or more surfaces at an appropriate initiation temperature. In some instances, the residence time of a given gaseous species may be defined as the total amount of time the species spends in the reaction chamber before escaping or undergoing polymerization. The residence times of the monomers, initiators, and inert gases may each be independently any suitable value. In some cases, each of the one or more monomers, initiators, and inert gases may independently have a residence time of greater than or equal to 5 seconds, greater than or equal to 10 seconds, greater than or equal to 15 seconds, greater than or equal to 30 seconds, greater than or equal to 45 seconds, greater than or equal to 60 seconds, greater than or equal to 90 seconds, greater than or equal to 120 seconds, or greater than or equal to 180 seconds. In some cases, each of one or more monomers, initiators, and inert gases may have a residence time of less than or equal to 300 seconds, less than or equal to 180 seconds, less than or equal to 120 seconds, less than or equal to 90 seconds, less than or equal to 60 seconds, less than or equal to 45 seconds, less than or equal to 30 seconds, less than or equal to 15 seconds, or less than or equal to 10 seconds. Combinations of the above-mentioned ranges are also possible (e.g., greater than or equal to 15 seconds and less than or equal to 90 seconds). In some embodiments, the residence times of all substances are substantially similar. In some cases, the SACVD method for forming/depositing a polymer coating may include one or more deposition cycles.

d. Polymer Coating In certain examples of SACVD methods, polymer coating deposition includes forming a polymer on one or more surfaces, such as a substrate or a device, at any suitable deposition rate. In some examples, the deposition rate can be greater than or equal to 0.01 nm/min, greater than or equal to 0.025 nm/min, greater than or equal to 0.05 nm/min, greater than or equal to 0.1 nm/min, greater than or equal to 0.25 nm/min, greater than or equal to 0.5 nm/min, greater than or equal to 1 nm/min, greater than or equal to 2.5 nm/min, greater than or equal to 5 nm/min, greater than or equal to 10 nm/min, greater than or equal to 25 nm/min, or greater than or equal to 50 nm/min. In some cases, the deposition rate can be less than or equal to 100 nm/min, less than or equal to 50 nm/min, less than or equal to 25 nm/min, less than or equal to 10 nm/min, less than or equal to 5 nm/min, less than or equal to 2.5 nm/min, less than or equal to 1 nm/min, less than or equal to 0.5 nm/min, less than or equal to 0.25 nm/min, less than or equal to 0.1 nm/min, less than or equal to 0.05 nm/min, or less than or equal to 0.025 nm/min. Combinations of the above-mentioned ranges are also possible (e.g., greater than or equal to 0.025 nm/min and less than or equal to 1 nm/min). In some cases, as discussed above, the initiation temperature is selected to provide a deposition rate of the polymer of at least 0.5 nm/min to form a polymer coating.

According to some embodiments, the polymer coating may be formed on at least a portion of, all of, or substantially all of one or more surfaces of, for example, a substrate or device. As described below, any suitable substrate or device may be used in a suitable SACVD process. As noted, in some SACVD processes, the surface to be coated with the polymer is the surface of the reactor itself in which the SACVD process is performed.

In instances where the polymer coating is formed on substantially all or all of the surface, the polymer coating substantially encompasses or covers substantially all of the surface to be coated (e.g., greater than about 99%, about 99.5%, about 99.8%, about 99.9%, about 99.99%, or 100% of the surface to be coated by the polymer). In such instances as described herein, the polymer coating may protect the substrate or device (e.g., from harmful environmental conditions (such as high temperature and/or humidity); and from harmful electrical effects/conditions by providing electrical insulation). In other instances, only a portion of the substrate is covered by the polymer coating.

In some cases, the polymer coating formed by the SACVD method described herein is formed as a polymer coating on one or more surfaces of a substrate or device, for example. Such polymer coatings can have any suitable average thickness. In some examples, the average thickness of the polymer coating can be greater than or equal to 1 nm, greater than or equal to 5 nm, greater than or equal to 10 nm, greater than or equal to 15 nm, greater than or equal to 20 nm, greater than or equal to 25 nm, greater than or equal to 50 nm, greater than or equal to 75 nm, greater than or equal to 100 nm, greater than or equal to 250 nm, greater than or equal to 500 nm, greater than or equal to 750 nm, greater than or equal to 1 µm, greater than or equal to 2.5 µm, greater than or equal to 5 µm, greater than or equal to 7.5 µm, greater than or equal to 10 µm, greater than or equal to 25 µm, or greater than or equal to 50 µm. In some examples, the average thickness of the polymer coating may be less than or equal to 100 μm, less than or equal to 50 μm, less than or equal to 25 μm, less than or equal to 10 μm, less than or equal to 7.5 μm, less than or equal to 5 μm, less than or equal to 2.5 μm, less than or equal to 1 μm, less than or equal to 750 nm, less than or equal to 500 nm, less than or equal to 250 nm, less than or equal to 100 nm, less than or equal to 75 nm, or less than or equal to 50 nm. Combinations of the above-mentioned ranges are also possible (e.g., greater than or equal to 50 nm and less than or equal to 10 μm, greater than or equal to 100 nm and less than or equal to 10 μm, or greater than or equal to 100 nm and less than or equal to 1 μm).

As explained above, polymer coatings formed by SACVD typically exhibit a high degree of uniformity. In some cases, the thickness of the polymer coating may be substantially the same throughout the coating. The thickness of the polymer coating may be determined by measuring the thickness of the polymer coating at a plurality of regions (e.g., at least 2, at least 4, at least 6, at least 10, at least 20, at least 40, at least 50, at least 100 or more regions) and calculating the average thickness.

Those skilled in the art will be aware of methods for determining the thickness of polymer coatings. In one method, a witness sample, i.e., a substrate with a smooth surface such as a silicon or glass wafer, is placed in a deposition chamber during polymer coating. After deposition, a scribe is made on the witness sample until the substrate is exposed, and the thickness of the coating is measured using a contact profiler.

e. Substrates and Devices The substrate or device may have any size or shape. Non-limiting examples of shapes include sheets, cubes, cylinders, hollow tubes, spheres, and the like. The substrate or device may have any suitable size. In some examples, the substrate or device comprises metal and/or polymer material (e.g., plastic, elastomer).

The substrate or device may be or include a variety of suitable articles, non-limiting examples of which include seals, gaskets, o-rings, and molds. In some examples, the substrate or device may include, but is not limited to, microelectronic devices, microelectromechanical systems (MEMS), microfluidics, 3-D integrated heterogeneous packages (IHP), CMOS chips, radio frequency (RF) devices, microchips, boards, transistors, ultra-high-speed mixed signal circuits, power devices, switches, clock references, frequency selective filters, miniaturized arrays, digital-to-analog converters, analog-to-digital converters, and/or low-noise amplifiers.

In some cases, the device may include indium phosphide and silicon, such as in an indium phosphide bipolar CMOS integrated circuit. The indium phosphide bipolar CMOS circuit may include both an indium phosphide heterojunction bipolar transistor and silicon CMOS. In some cases, the device may include gallium nitride, gallium arsenide, and silicon. For example, the device may include a gallium nitride or gallium arsenide high electron mobility transistor and silicon CMOS. In some cases, the device may include indium phosphide, gallium nitride, gallium arsenide, and silicon. In some cases, the devices may include Indium Phosphide Heterojunction Bipolar Transistors, Gallium Nitride High Electron Mobility Transistors, Gallium Arsenide High Electron Mobility Transistors, and Silicon CMOS. Other combinations of semiconductors and compound semiconductors may also be used for the devices to be coated.

In some cases, polymer coatings may be deposited on silicon wafers by SACVD during microchip formation, such as polymer coatings on through silicon vias (TSVs).

The substrate or device may include one or more depressions in its surface. These depressions may have any suitable depth.

The SACVD methods described herein are particularly suitable for forming polymers on substrates or devices of any shape and/or size. In some cases, the largest dimension of the substrate in any dimension may be at least about 1 mm, at least about 1 cm, at least about 5 cm, at least about 10 cm, at least about 1 m, at least about 2 m, or more. In some cases, the smallest dimension of the substrate in one dimension may be less than about 50 cm, less than about 10 cm, less than about 5 cm, less than about 1 cm, less than about 10 mm, less than about 1 mm, less than about 1 um, less than about 100 nm, less than about 10 nm, less than about 1 nm, or less. The substrate or device may or may not be substantially flat. For example, the substrate or device may include ripples, waves, trees, spheres (e.g., nanospheres), rods (e.g., nanorods), powders, precipitates, a plurality of particles, and the like.

In other examples, where the surface to be coated by the polymer film is the surface of a reactor, the reactor may have any suitable shape capable of performing a SACVD process. Non-limiting examples may include a hollow tube. Such shapes may include one or more depressions in their surface. The depressions may have any suitable depth.

In some cases, the substrate, device, or reactor may undergo one or more preparation steps before the polymer coating is applied thereto. Several possible preparation steps are described below. For example, in some cases, the substrate, device, or reactor may be cleaned by exposing the substrate, device, or reactor to a fluid and then immersing the substrate, device, or reactor in the fluid, rinsing the substrate, device, or reactor with the fluid, and/or sonicating the substrate, device, or reactor in the presence of the fluid prior to the reaction. Non-limiting examples of suitable fluids for such methods include organic solvents, water, and/or solutions comprising organic or aqueous solvents and surfactants.

In some cases, the substrate, device, or reactor may be exposed to elevated temperatures and/or reduced pressures to remove volatile contaminants. Suitable temperatures include temperatures between 20° C. and 300° C. Suitable pressures include pressures between 0.1 mTorr and 1 atm.

According to some embodiments, the substrate, device or reactor may undergo a plasma cleaning step prior to the reaction. Other preparation steps are also possible.

In some embodiments, one or more adhesion-promoting linkers may be applied to the substrate, device, or reactor prior to depositing the polymer coating. Non-limiting examples of such linkers include silane-containing compounds, organic phosphate-containing compounds, and thiol-containing compounds.

f. Annealing Optional During SACVD Process In certain instances, the SACVD methods described herein may further include an annealing step. The annealing step may be performed during or after the flow step (iv). The annealing step may include transferring the substrate or device having the polymer coating thereon to another chamber, where the annealing step is performed. The annealing step may occur at a temperature ranging from about 200°C to 800°C, 200°C to 750°C, 200°C to 700°C, 200°C to 650°C, 200°C to 600°C, 200°C to 550°C, 200°C to 500°C, 200°C to 450°C, 200°C to 400°C, 200°C to 350°C, or 200°C to 250°C. The annealing step may be performed under a process gas selected from nitrogen, argon, ammonia, hydrogen, forming gas, and combinations thereof; optionally wherein the process gas does not contain or substantially does not contain oxygen (O ₂ ) gas; or wherein the process gas includes oxygen (O ₂ ) gas or air. The annealing step may occur for a period ranging from about 5 minutes to about 3 hours.

In some cases, after the annealing step, the density of the polymer coating is greater than the polymer coating formed in step (iv). In some cases, the annealing step occurs after step (iv), and after the annealing step, the mass of the polymer coating is about 50%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5% or less of the mass of the polymer coating formed in step (iv).

g. Physical Properties of Conformal Polymer Coatings As noted above, conformal polymer coatings formed by the methods described herein may protect substrates or devices from harmful environmental and/or electrical effects/conditions. In some cases, the environmental effects/conditions may be biological environmental effects/conditions. The polymer coating may maintain one or more of these benefits, effects, or properties for a period of at least one day, at least one week, at least one month, at least one year, at least 10 years, at least 25 years, or at least 100 years.

In some examples, the water vapor permeability of the polymer coating can be greater than or equal to 250 g/m ² /day, greater than or equal to 500 g/m ² /day, greater than or equal to 750 g/m ² /day, greater than or equal to 1000 g/m ² /day, greater than or equal to 1250 g/m ² /day, greater than or equal to 1500 g/m ² /day, greater than or equal to 1750 g/m ² /day, greater than or equal to 2000 g/m ² /day, or greater than or equal to 2250 g/m ² /day. According to some examples, the film can comprise a water vapor permeability of less than or equal to 2500 g/m ² /day, less than or equal to 2250 g/m ² /day, less than or equal to 200 g/m ² /day, less than or equal to 1750 g/m ² /day, less than or equal to 1500 g/ ^{m 2 /} day, less than or equal to 1250 g/m ² /day, less than or equal to 1000 g/m ² /day, less than or equal to 750 g/m 2 /day, or less than or equal to 500 g/m ² /day. Combinations of the above-mentioned ranges are also possible (e.g., greater than or equal to 250 g/m ² /day and less than or equal to 2250 g/m ² /day, greater than or equal to 500 g/m ² /day and less than or equal to 2000 g/m ² /day, or greater than or equal to 1000 g/m ² /day and less than or equal to 1500 g/m ² /day). One of ordinary skill in the art will be familiar with methods for determining water vapor permeability. In some instances, water vapor permeability can be evaluated using ASTM E398.

In some instances, the polymer coating may be able to pass the military specification for Insulating Compound, Electrical (for Coating Printed Circuit Assemblies), published as MIL-I-46058C, July 7, 1972, which is incorporated herein by reference in its entirety for all purposes. This specification describes the properties that a film must possess in order to be suitable for use as a coating on printed circuit assemblies for the Department of Defense.

In some instances, a polymer coating suitable under MIL-I-46058C does not contain deleterious substances, is chemically compatible with the materials used to form the printed circuit assembly, does not cause degradation of any materials used to form the printed circuit assembly, and does not corrode any metal being coated.

In some cases, a polymer coating suitable under MIL-I-46058C may be resistant to fungi. The coating may show no fungal growth when evaluated by ASTM G-21, which involves placing three glass samples coated with the film in a petri dish filled with minimal salt agar, spraying fungal spores in a minimal salt solution onto the samples, sealing the samples, and incubating them for 28 days. Photographs of each sample are taken at regular time intervals and compared to photographs taken of both a positive control (uncoated substrate) and a negative control (solid agar medium not exposed to spores). Fungal spores include those from the following genera: Penicillium, Aspergillus, Chaetomium, Trichoderma, Aureobasidium,

In some examples, a polymer coating suitable under MIL-I-46058C may have an insulation resistance greater than or equal to 1.5×10 ¹² ohms and less than or equal to 10 ¹⁴ ohms, or greater than or equal to 2.5×10 ¹² ohms and less than or equal to 10 ¹⁴ ohms. The insulation resistance may be measured using the procedure described in MIL-STD-202 for Method 302, Test Condition B. This test condition involves coating a film over a megaohm bridge, applying 500 +/- 10% V to the megaohm bridge for one minute, and then measuring the insulation resistance on the film.

In some instances, a suitable polymer coating under MIL-I-46058C may not exhibit a flashover, sparking, breakdown, or leakage rate exceeding 10 microamperes when tested using the procedure described in MIL-STD-202 for Method 301. This procedure consists of applying 1500 V ac, rms, at 60 Hz between two mutually insulated portions of the specimen for 60 seconds.

In some cases, a polymer coating suitable under MIL-I-46058C may have advantageous properties after being subjected to thermal shock as described in MIL-STD-202, Method 107. The coating may be subjected 50 times in the sequence of -70-65°C, 20-35°C, 200-205°C, and 20-35°C for the times specified in MIL-STD-202 Method 107 (e.g., 15 minutes for samples weighing less than or equal to 1 ounce; 30 minutes for samples weighing greater than 1 ounce and less than or equal to 0.3 pounds; 1 hour for samples weighing greater than 0.3 pounds and less than or equal to 3 pounds; 2 hours for samples weighing greater than 3 pounds and less than or equal to 30 pounds; 4 hours for samples weighing greater than 30 pounds and less than or equal to 300 pounds; 8 hours for samples weighing greater than 300 pounds). The coating can then be kept at 23°C-27°C and 45-55% relative humidity for 35 hours. After this test, the coating can show suitable properties after microscopic examination and subjection to MIL-STD-202 Method 301 as described above.

In some instances, a polymer coating suitable under MIL-I-46058C may be subjected to a modification of the procedure described in MIL-STD-202 for Method 106 and thereafter exhibit an insulation resistance greater than or equal to 1.5×10 ¹² ohms and less than or equal to 10 ¹⁴ ohms, or greater than or equal to 2.5×10 ¹² ohms and less than or equal to 10 ¹⁴ ohms, suitable properties after examination using microscopy, and may not exhibit a flashover, sparking, breakdown, or leakage rate exceeding 10 microamperes when tested using the procedure described in MIL-STD-202 for Method 301. The modified method comprises exposing the coating to a cycle of steps having defined humidity comprising a range of 80%-100% relative humidity and a temperature ranging from 25° C. to 65° C. The coating may then be maintained at 25+/-2° C. and 50+/-5% relative humidity for 24 hours.

According to some examples, the polymer coating may meet the requirements detailed in the publication "IPC-CC-830B with Amendment 1 Qualification and Performance of Electrical Insulating Compounds for Printed Wiring Assemblies," published October 2008, which is incorporated herein by reference in its entirety for all purposes. This publication details performance metrics for the coating.

In some cases, the polymer coatings may meet the requirements detailed in the publication "PC-CC-830B with Amendment 1 Qualification and Performance of Electrical Insulating Compounds for Printed Wiring Assemblies" regarding appearance. The coatings may not exhibit harmful materials, bubbles, pinholes, white spots, blistering, cracking, flaking, cracking, chalking, signs of recovery, or signs of corrosion. The coatings may be smooth, uniform, transparent or translucent, and non-tacky. The films may be examined to determine these characteristics at 10× magnification.

In some cases, the polymer coating can meet the requirements for fungal resistance detailed in the publication "IPC-CC-830B with Amendment 1 Qualification and Performance of Electrical Insulating Compounds for Printed Wiring Assemblies". After inoculation with spores, incubation for 28 days at 28°C-30°C and 85% relative humidity, and subsequent evaluation to determine fungal growth, the coating may not promote or be challenged by biological growth. Fungal spores may include spores from Aspergillus niger, Chaetomium globosum, Gliocadium virans, Aureobasidium pullulans, and Penicillium funiculosum.

In some cases, the polymer coating may meet the requirements for dielectric withstand voltage as detailed in publication PC-CC-830B with Amendment 1 Qualification and Performance of Electrical Insulating Compounds for Printed Wiring Assemblies. The coating may not exhibit flashover, sparking, breakdown, or leakage rates exceeding 10 microamperes after being subjected to IPC-TM-650, Test Method 2.5.7.1. This test involves subjecting the coating to 1500 VAC at 50 to 60 Hz for one minute.

In some cases, the polymer coating can meet the requirements for moisture and insulation resistance detailed in publication "IPC-CC-830B with Amendment 1 Qualification and Performance of Electrical Insulating Compounds for Printed Wiring Assemblies". Meeting these requirements can include having certain desirable properties after testing the coating in accordance with IPC-TM-650, Test Method 2.6.3.4. This test method includes forming the coating on a substrate including a test pattern, preconditioning the film at 50+/-2°C for 24 hours, cooling the coating to room temperature, applying a 50 VDC polarized bias to the test pattern, and exposing the coating to 20 temperature and humidity cycles. At the end of the test, the coating may be maintained at 25+/-2°C and 50+/-5% relative humidity for 24 hours. The temperature and humidity cycle consists of increasing the temperature from 25°C to 65°C over a span of 1.75+/-0.75 hours, maintaining the temperature at 65°C for 3-3.5 hours, and then decreasing the temperature to 25°C over 1.75+/-0.5 hours. The resistance of the coating may be measured after the first cycle between the second and third hours of the high temperature step, the fourth cycle, the seventh cycle, and the tenth cycle. The resistance of the coating may also be measured at the end of the test. In some cases, at the end of the testing, the coating may exhibit an insulation resistance of at least 5000 megohms, may have a dielectric withstand voltage as described above at the end of the testing, and may meet the appearance requirements as described above at the end of the testing.

In some cases, the polymer coating can meet the requirements detailed in the publication "PC-CC-830B with Amendment 1 Qualification and Performance of Electrical Insulating Compounds for Printed Wiring Assemblies" for thermal shock. The coating can show acceptable dielectric withstand voltage and appearance after being subjected to IPC-TM-650, Test Method 2.6.7.1. This test method involves exposing the coating to 100 temperature cycles, where the coating is cycled from -65°C to 125°C, and then the film is kept at 25+/-5°C for 24 hours.

In some cases, the polymer coating can meet the requirements for hydrolytic stability detailed in publication PC-CC-830B with Amendment 1 Qualification and Performance of Electrical Insulating Compounds for Printed Wiring Assemblies. The coating can meet the appearance criteria described above and can be tack-free after being subjected to IPC-TM-650 test method 2.6.11.1. This test method includes placing the coating on a ceramic plate in a desiccator containing a saturated solution of deionized water and potassium sulfate at 85+/-2°C, closing the desiccator, sealing the desiccator with high temperature silicone grease, and placing the sealed desiccator in an oven maintained at 85+/-2°C for 120 days. Following this treatment, the coatings were maintained at 25°C and 50% relative humidity for 7 days. The coatings were also allowed to reach 25°C and 50% relative humidity for two hours and then tested at 28, 56 and 84 days.

In some instances, the polymer coating may be able to pass one or more of the tests detailed in Methods 507.5 and 509.5 of the Department of Defense Test Method Standard Environmental Engineering Considerations and Laboratory Tests, published as MIL-STD-810G on October 31, 2008, and incorporated herein by reference in its entirety for all purposes.

Method 507.5 of the Department of Defense Test Method Standard Environmental Engineering Considerations and Laboratory Tests, published as MIL-STD-810G on October 31, 2008, describes a procedure for determining the resistance of a protective coating on a material to a warm, humid atmosphere. In some embodiments, after the test is completed, the coating is able to undergo this procedure and have properties (e.g., water vapor permeability, defect-free, dielectric constant, dielectric breakdown voltage, adhesion strength, and the like) that fall within the parameters described herein. In some individual cases, the coating is able to undergo this procedure and exhibit a dielectric breakdown voltage and/or dielectric constant change of less than 25%, less than 10%, less than 5%, less than 2%, or less than 1%.

The stress cycle of method 507.5 in MIL-STD-810G, October 31, 2008, includes placing the coated substrate or device in a chamber and exposing it to a temperature of 23+/-2°C and a humidity of 50+/-5% relative humidity for a period of at least 24 hours. Subsequently, the temperature of the chamber is increased to 30°C, and the relative humidity of the chamber is increased to 95%. Next, the coated substrate or device is subjected to 10 cycles, wherein each cycle includes increasing the temperature from 30°C to 60°C over a period of 2 hours, maintaining the temperature at 60°C for 6 hours, cooling the temperature to 30°C over 8 hours, and maintaining the temperature at 30°C for 8 hours. At the end of 10 cycles, the temperature of the chamber is returned to 30 +/- 2°C and the humidity of the chamber is returned to 50 +/- 5% relative humidity. The coated substrate or device is maintained under these conditions until the coated substrate or device achieves temperature stability.

Department of Defense Test Method Standard Environmental Engineering Considerations and Method 509.55 in Laboratory Testing, published as MIL-STD-810G on October 31, 2008, describes a procedure for evaluating the effectiveness of a protective coating on a material when exposed to salt. In some embodiments, at the end of the test, the film is able to undergo this procedure and have properties (e.g., water vapor permeability, defect free, dielectric constant, dielectric breakdown voltage, adhesion strength, and the like) that fall within the parameters described herein. In some instances, the coating is able to undergo this procedure and exhibit a change in dielectric breakdown voltage and/or dielectric constant of less than 25%, less than 10%, less than 5%, less than 2%, or less than 1%.

Method 509.5 5 of MIL-STD-810G dated October 31, 2008, involves placing the coated substrate or device in a chamber, regulating the temperature to 35°C, and conditioning the coated article at this temperature for at least two hours. Next, a solution of 5% sodium chloride in water is continuously atomized into the test chamber for 24 hours. The salt mist settling rate and the pH of the settling solution are measured every 24 hours, and the settling is maintained between 1 and 3 mL/80 ^cm2 /hour. The coated substrates or devices are then dried for 24 hours at standard ambient temperature and less than 50% relative humidity, after which the coated articles are again exposed to the atomized salt solution for 24 hours and then dried again for 24 hours. The coated substrates or devices are then photographed, rinsed with running water under standard ambient conditions, and then inspected for evidence of corrosion. The extent of salt deposits is noted, the substrates or devices are tested for electrical failure, and any observed corrosion is evaluated to determine its immediate and potential long-term effects on the functionality and structural integrity of the substrate or device.

In some cases, the polymer coating may be able to pass one or more tests published by JEDEC. As used herein, a coating that passes the tests published by JEDEC is capable of undergoing a JEDEC procedure and having properties (e.g., water vapor permeability, defect-free, dielectric constant, dielectric breakdown voltage, adhesion strength, and the like) that fall within the parameters described herein at the end of the procedure. In some cases, the polymer coating is capable of undergoing one or more JEDEC procedures and exhibiting a dielectric breakdown voltage and/or dielectric constant variation of less than 25%, less than 10%, less than 5%, less than 2%, or less than 1%.

For example, a polymer coating may be able to pass the JEDEC Standard No. 22-A101C: Steady State Temperature Humidity Bias Life Test published in March 2009, and incorporated herein by reference in its entirety for all purposes. The JEDEC Standard No. 22-A101C: Steady State Temperature Humidity Bias Life Test involves exposing the film to stress conditions including a temperature of 85+/-2°C and a relative humidity of 85+/-5% for 976 to 1168 hours under a 10 V dc bias. The sample is then cooled to ambient temperature and maintained there for up to 48 hours. Electrical testing can then be performed on the coating. Optionally, the coated substrate or device may be returned to the stress condition within 96 hours of cooling.

According to certain examples, the polymer coating may be able to pass the JEDEC Standard No. 22-A110D: Highly Accelerated Temperature and Humidity Stress Test (HAST), published in January 2009, and incorporated herein by reference in its entirety for all purposes. JEDEC Standard No. 22-A110D involves exposing the coating to stress conditions of 130 +/- 2°C and 85 +/- 5% relative humidity for 96 to 98 hours under 10 V dc bias conditions. The sample is then cooled to ambient temperature and maintained there for up to 48 hours. Electrical testing can then be performed on the film. Optionally, the coated substrate or device may be returned to the stress condition within 96 hours of cooling.

In some cases, the polymer coating may be able to pass the JEDEC Standard No. 22-A100D: Cycled Temperature-Humidity-Bias Life Test published in July 2013, which is incorporated herein by reference in its entirety for all purposes. This test involves exposing the coating to an experimental profile that includes increasing the temperature from 30°C to 65°C in 2-4 hours at 80%-98% relative humidity, a constant temperature of 65°C for 4-8 hours at 90%-98% relative humidity, and decreasing the temperature from 65°C to 30°C in 2-4 hours at 80%-90% relative humidity. This cycle is repeated for a duration between 1084 and 1172 hours while the coating is under 10 V dc bias. The coating is then cooled to ambient temperature and held there for up to 48 hours. The membrane can then be electrically tested. Optionally, the device can be returned to stress conditions within 96 hours of cooling.

In some instances, the polymer coating may be capable of passing testing according to ASTM B117-16 Standard Practice for Operating Salt Spray (Mist Apparatus), published March 2016, which is incorporated herein by reference in its entirety for all purposes. In some instances, the polymer coating may be capable of undergoing the procedures outlined in ASTM B117-16 and having properties (e.g., water vapor permeability, freedom from defects, dielectric constant, dielectric breakdown voltage, adhesion strength, and the like) that fall within the parameters described herein at the end of the procedure. In some cases, the polymer coating is capable of undergoing the procedure outlined in ASTM B117-16 and exhibiting a dielectric breakdown voltage and/or dielectric constant change of less than 25%, less than 10%, less than 5%, less than 2%, or less than 1%. Conducting the ASTM B117-16 test involves placing the coating in a chamber maintained at 35+/-2°C and exposing the coating to a mist of a salt solution containing 5 wt% sodium chloride at a pH between 6.5 and 7.2 twice for 24 hours.

In some instances, the ability of a polymer coating to pass one or more standardized tests may be substantially unaffected by being subjected to stress testing and/or being subjected to elongation. In some instances, the percent elongation may be defined as the difference between the elongated length and the initial length divided by the initial length. According to certain instances, the polymer coating may maintain its ability to pass one or more standardized tests after undergoing an elongation of greater than or equal to 1%, greater than or equal to 2%, greater than or equal to 3%, or greater than or equal to 5%. The coating may be deposited on a flexible substrate (e.g., PET, liquid crystal polymer, and the like) that includes conductive traces. Appropriate properties (e.g., dielectric breakdown voltage, dielectric constant, defect and/or pinhole concentration) may then be evaluated prior to elongation. An extensometer (such as an Instron 5900) can be used to stretch the coating, and appropriate properties can be measured again after stretching.

In some instances, polymer coatings synthesized by the SACVD methods described herein may include certain dielectric properties. It is believed that the dielectric constant of the coating may be affected by the composition of the coating. According to some instances, polymer coatings including a higher level of organic content may exhibit a lower dielectric constant. In some cases, the polymer coating can exhibit a dielectric constant greater than or equal to 2.0, greater than or equal to 2.1, greater than or equal to 2.2, greater than or equal to 2.3, greater than or equal to 2.4, greater than or equal to 2.5, greater than or equal to 2.6, greater than or equal to 2.65, greater than or equal to 2.7, greater than or equal to 2.75, greater than or equal to 2.8, greater than or equal to 2.85, greater than or equal to 2.9, greater than or equal to 2.95, greater than or equal to 3.0, greater than or equal to 3.05, greater than or equal to 3.1, or greater than or equal to 3.15. According to some examples, the polymer coating can exhibit a dielectric constant of less than or equal to 3.2, less than or equal to 3.15, less than or equal to 3.1, less than or equal to 3.05, less than or equal to 3.0, less than or equal to 2.95, less than or equal to 2.9, less than or equal to 2.85, less than or equal to 2.8, less than or equal to 2.75, less than or equal to 2.7, less than or equal to 2.65, less than or equal to 2.6, less than or equal to 2.5, less than or equal to 2.4, less than or equal to 2.3, less than or equal to 2.2, less than or equal to 2.1, or less than or equal to 2.0. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 2.0 and less than or equal to 3.0, greater than or equal to 2.0 and less than or equal to 2.75, or greater than or equal to 2.0 and less than or equal to 2.7).

According to some examples, the polymer coating can exhibit a dielectric breakdown voltage. In some examples, the polymer coating can exhibit a dielectric breakdown voltage measured in V/mil, where a mil is a unit of measurement equivalent to 0.001 inch. In some examples, the polymer coating can exhibit a dielectric breakdown voltage of greater than or equal to 1000 V/mil, greater than or equal to 1500 V/mil, greater than or equal to 2000 V/mil, greater than or equal to 2500 V/mil, greater than or equal to 3000 V/mil, greater than or equal to 3500 V/mil, greater than or equal to 4000 V/mil, greater than or equal to 4500 V/mil, greater than or equal to 5000 V/mil, greater than or equal to 5500 V/mil, greater than or equal to 6000 V/mil, greater than or equal to 7500 V/mil, greater than or equal to 8000 V/mil, greater than or equal to 8500 V/mil, greater than or equal to 9000 V/mil, or greater than or equal to 9500 V/mil. According to some examples, the polymer coating may exhibit a V/mil less than or equal to 10,000 V/mil, less than or equal to 9,500 V/mil, less than or equal to 9,000 V/mil, less than or equal to 8,500 V/mil, less than or equal to 8,000 V/mil, less than or equal to 7,500 V/mil, less than or equal to 7,000 V/mil, less than or equal to 6,500 V/mil, less than or equal to 6,000 V/mil, less than or equal to 5,500 V/mil, less than or equal to 5,000 V/mil, less than or equal to 4,500 V/mil, less than or equal to 4,000 V/mil, less than or equal to 3,500 V/mil, less than or equal to 3,000 V/mil, less than or equal to 2,500 V/mil, less than or equal to 2,000 V/mil, V/mil or a dielectric breakdown voltage of less than or equal to 1500 V/mil. Combinations of the above ranges are also possible (e.g., greater than or equal to 2500 V/mil and less than or equal to 8500 V/mil, greater than or equal to 4000 V/mil and less than or equal to 7000 V/mil, or greater than or equal to 6000 V/mil and less than or equal to 10000 V/mil).

The dielectric breakdown voltage of a polymer coating can be measured by ASTM D149 using a step-by-step method, which involves exposing the coating to a voltage that is uniformly increased from zero until the dielectric breakdown voltage is reached. Next, the fresh coating is exposed to a voltage at 50% of the measured breakdown voltage, and the voltage is increased in a step-by-step manner until breakdown is reached. The dielectric breakdown voltage of the coating is taken to be the voltage measured using the step-by-step test.

In some cases, the polymer coating can retain a percentage of its initial adhesive strength after undergoing mechanical cycling. The percentage of initial adhesive strength retained can be defined as the adhesive strength of the coating after being subjected to flexure and/or elongation divided by the initial coating adhesive strength. According to some cases, the percentage of initial adhesive strength retained can be greater than or equal to 50%, greater than or equal to 75%, greater than or equal to 80%, greater than or equal to 85%, greater than or equal to 90%, greater than or equal to 95%, or greater than or equal to 99%. Flexing and elongating the coating can include forming the coating on a flexible substrate and then placing the flexible substrate over the hinge. The hinge then undergoes ten cycles, each of which includes bending the hinge to 130°, holding the hinge in this position for one second, returning the hinge to the unbent position, and then holding the hinge in the unbent position for one second. Following this test procedure, any suitable properties of the coating may be measured in the manner described herein.

The adhesion strength of the coating can be determined by the method described in ASTM D3359, which includes cutting the coating in a lattice pattern, cutting eleven cuts in each direction, applying a pressure-sensitive adhesive tape to the cuts, removing the pressure-sensitive adhesive tape, and evaluating the adhesion by determining the degree of removal of the coating. The percentage of adhesion strength retained after mechanical cycling is the ratio of the percentage of the coating retained by the coating that has undergone mechanical cycling within the lattice pattern to the percentage of the coating retained by the coating that has not undergone mechanical cycling within the lattice pattern.

With respect to the resistance to biological environments provided by the polymer coatings discussed, one of ordinary skill in the art will understand methods and systems for exposing the coated substrate or device to a biological environment or biological fluid. The term "biological environment" is given its ordinary meaning in this art and generally refers to the body of an individual (e.g., a mammalian patient, such as a human patient). However, the term "biological environment" may also include an in vitro environment (e.g., a temperature of about 37° C. and saline or Ringer's solution) that models a desired in vivo environment. In some instances, the coated substrate or device may be exposed to a biological environment or biological fluid by being implanted in or on an individual (e.g., a human).

In some cases, the polymer coating can exhibit a leakage current of less than or equal to 10-15 A, less than or equal to 10-14 A, less than or equal to 10-13 A, less than or equal to 10-12 A, less than or equal to ^{10-10 A} , or less than or equal to 10-8 ^A after exposure to a biological environment or biological fluid for a period of at least one day, at least one week, at least one month, at least one ^year , at least two years, at least three years, at ^{least four} years, at least ^five years, at least ^ten years, at least twenty years, at least twenty ^{- five} years, or at least ^{one hundred} years. The leakage current can be determined by placing the coated device in saline water and measuring the current flowing through the coating.

In some cases, the polymer coating can exhibit a dielectric breakdown voltage greater than or equal to 5000 V/mil after exposure to a biological environment or biological fluid for a period of at least one day, at least one week, at least one month, at least one year, at least two years, at least three years, at least four years, at least five years, at least ten years, at least twenty years, at least twenty-five years, or at least one hundred years. In some cases, the polymer coating can exhibit a dielectric breakdown voltage that is within 25%, within 10%, within 5%, within 2%, or within 1% of an otherwise identical film that is not exposed to a biological environment or biological fluid after exposure to a biological environment or biological fluid for a period of at least one day, at least one week, at least one month, at least one year, at least two years, at least three years, at least four years, at least five years, at least ten years, at least twenty years, at least twenty-five years, or at least one hundred years. The dielectric breakdown voltage of the coating can be measured by ASTM D149 as described above.

In some cases, the polymer coating can retain at least 50%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of its initial adhesion after exposure to a biological environment or biological fluid for a period of at least one day, at least one week, at least one month, at least one year, at least two years, at least three years, at least four years, at least five years, at least ten years, at least twenty years, at least twenty-five years, or at least one hundred years. In some cases, the polymer coating can be a biocompatible material, such as a USP Class VI material.

In some cases, the polymer coating formed by the described SACVD method is free or substantially free of pinholes and/or defects. "Substantially free of pinholes and/or defects" means that less than about 5%, 4%, 3%, 2%, or 1% of the surface of the polymer coating exhibits such pinholes or defects based on evaluation of the coating using methods known in the art.

III. Surface Activated Chemical Vapor Deposition ( SACVD ) System In certain examples of the described SACVD methods, the SACVD process can be performed in a SACVD system, the system comprising: a reaction chamber comprising a platform capable of supporting at least one substrate or device in the reaction chamber; the platform comprising one or more heating elements for independently heating the platform to a first temperature; a temperature sensor for measuring and providing feedback about the first temperature of the platform; wherein the reaction chamber and/or its components can be independently heated to a second temperature lower than the first temperature; at least one gas inlet port for introducing one or more gaseous reactants and, optionally, a carrier gas, into the reaction chamber; at least one gas outlet port; a first temperature controller for setting the first temperature of the platform; a second temperature controller for setting the second temperature of the reaction chamber; one or more gas metering valves and/or mass flow controllers, if applicable; a pressure converter, if applicable; a throttling valve, if applicable; and a vacuum source, if applicable.

In a non-limiting example, a system for SACVD is shown in FIG. 2 , wherein the SACVD system 200 includes a reaction chamber 210, a tubular furnace 220, a carrier gas container 230, a carrier gas mass flow controller 235, an initiator container 240, an initiator metering valve 245, a monomer container 250, a pressure converter 260, a throttling valve 270, and a vacuum source 280.

In some cases, the platform holding the substrate or device is formed of a material selected to have a high degree of thermal uniformity and has a suitable configuration to provide good thermal contact with the substrate or device to ensure that the substrate or device itself is heated to a uniform temperature.

In some cases, the reaction chamber of the SACVD system as described above further includes a gas distributor for distributing one or more gaseous reactants and/or an optional carrier gas introduced through at least one gas inlet port into the reaction chamber.

In some cases, the gaseous reactants (i.e., monomers and initiators) and carrier gas are derived from a source in the form of a material reservoir (e.g., a container) that can be placed in fluid communication with the reaction chamber and/or removed from the fluid communication state via (inlet/outlet) ports. As an example, the source of gas or reactants can be in the form of and/or include a gas cylinder (e.g., having pressurized gas therein). The port can separate the reaction volume from the source and can be opened and/or closed to place the source in fluid communication with the reaction chamber and/or not in fluid communication. The port can be in direct or indirect fluid communication with the source. For example, the port can be in fluid communication with the source via a tube.

In some cases, the interface between the port and the reaction chamber can have a variety of suitable designs. In some cases, the port has a single opening, and when the port is open, the source is placed in communication with the reaction chamber fluid through the single opening. The single opening can have a variety of suitable shapes and sizes. For example, it can be circular, rectangular, square, etc. Some suitable ports have multiple openings. As a specific example, the port can include a plurality of openings. The plurality of openings can be positioned along the wall of the reaction chamber and/or along a tube present in the reaction chamber. In some cases, the system can include two sources and include a port in communication with the source and the reaction chamber fluid.

In some cases, a flow controller can be positioned between the source and the reaction chamber in addition to or in lieu of a port. As one example, in some cases, a mass flow controller is placed between the gas source and the reaction chamber. As another example, a throttle valve can be placed between the vacuum source and the reaction chamber.

As noted above, the system may also include a vacuum source. The vacuum source may be configured to evacuate the reaction chamber when in fluid communication with the reaction chamber. A variety of suitable types of vacuum sources may be used. As an example, in some instances, the vacuum source comprises a vacuum pump. The vacuum pump, when turned on and in fluid communication with the reaction volume, may evacuate the reaction volume by pumping out the contents of the reaction volume.

In some instances, the vacuum source has one or more characteristics that facilitate the removal of air and/or other gases from the reaction chamber. As an example, in some instances, the vacuum source is configured so that the removal of gases from the reaction volume occurs over a relatively slow period of time. Slow and/or controlled removal of gases from the reaction volume can be achieved by using a throttle valve positioned between the vacuum source and the reaction chamber. The throttle valve can limit the exposure of the reaction chamber to the vacuum source, and/or can be slowly opened to allow increased exposure of the reaction volume to the vacuum source over time. Such processes can cause the vacuum source to remove gases therefrom at a slower rate than if the vacuum source did not have such a throttle valve.

For example, the use of a vacuum may be advantageous when the reaction chamber initially contains a combination of gases that are not desired to be included in the reaction chamber during deposition of the fluorinated polymer coating. For example, and without wishing to be bound by any particular theory, it is believed that some gases may inhibit polymerization. Such gases may react with the growing polymer chain in a manner that terminates further growth before the growing polymer chain reaches a significant length, and/or may react with the monomer in a manner that renders it non-reactive before being incorporated into the growing polymer chain. Non-limiting examples of such gases include air, water vapor, acetone, and isopropanol. An example of a situation in which it may be necessary to remove one or more gases from the reaction chamber is at the end of a step performed during deposition of the polymer coating. During deposition of a polymer coating, the reaction volume may include a variety of reactive and/or toxic gases. It may be desirable to purge such gases from the reaction volume prior to performing one or more other processes. For example, if a system is employed to perform a method that includes sequentially depositing two layers having two different chemical compositions, it may be desirable to remove the gases that react to form the first layer prior to commencing deposition of the second layer. Removal of such species may facilitate deposition of the second layer having the desired chemical composition by preventing incorporation of reaction products of such gases into the second layer and/or deleterious reactions between such gases and gases configured to react to form the second layer. Another example of a situation in which it may be desirable to remove one or more gases from a reaction volume is at the end of a process for depositing a polymer coating. As described above, the reaction volume may contain reactive and/or toxic gases during coating deposition. It may be undesirable for operators to be exposed to such gases and/or for such gases to be released in an uncontrolled manner into the environment outside the reaction volume. Therefore, in such situations, it may be desirable to remove the gases present in the reaction volume from the reaction volume before the reaction volume is exposed to the environment outside of the reaction volume in order to retrieve the coated substrate or device at the end of the coating process.

In some other instances, the system may be configured so that one or more gases can be removed from the reaction volume by means other than placing a vacuum source in fluid communication with the reaction chamber. As an example, in some cases, the system may be configured so that one or more gases can be introduced into the reaction volume to displace other gases present in the reaction volume. For example, the system may be configured so that an inert gas (and/or a plurality of inert gases) can be introduced into the reaction volume to displace a reactive and/or toxic gas (and/or a plurality of reactive and/or toxic gases). The inert gas can be introduced from one or more sources in fluid communication with the reaction volume, such as one or more sources other than the source that supplies (and/or previously supplied) the reactive and/or toxic gas. One or more inert gases may be introduced into the reaction chamber by placing a vacuum source in fluid communication with the reaction volume or in conjunction with such a process, rather than removing the gases from the reaction volume. In the latter case, the vacuum source may exhaust both inert gases and reactive and/or toxic gases from the reaction volume when in fluid communication with the reaction volume. In one specific embodiment, the vacuum source may be placed in fluid communication with a reaction volume that includes reactive and/or toxic gases and is in fluid communication with one or more inert gas sources. The vacuum source may initially evacuate both types of gases. The inert gas source may then be removed from the fluid communication with the reaction volume while maintaining fluid communication between the vacuum source and the reaction volume. The vacuum source may then further evacuate any remaining gas in the reaction volume.

In some cases, the system includes an outlet that can be placed in fluid communication with the reaction chamber. The outlet can be configured to allow one or more gases present in the reaction chamber to flow out of the reaction volume when in fluid communication with the reaction chamber. The outlet can be in fluid communication with a location (such as an exhaust hood) to which gases present in the reaction volume can be safely exhausted. In some cases, the outlet can be in reversible fluid communication with the reaction chamber. For example, during the period when the reaction volume is in fluid communication with a vacuum source, the outlet can be removed from the fluid communication with the reaction chamber. It is also possible that the outlet can be configured so that gas can flow out of the reaction volume through the outlet, but gas cannot flow into the reaction volume through the outlet. For example, in some embodiments, the outlet may include a check valve, a gas bubbler, and/or another component that provides this functionality. In some cases, the outlet is configured to allow gas to flow into the reaction chamber and out of the reaction chamber, but the gas flowing into the reaction chamber (e.g., from one or more sources) can flow into the reaction chamber in sufficient quantity and/or at a sufficient rate that there is no significant flow from the outlet into the reaction chamber.

In some cases, the SACVD system chamber is a load lock chamber that can maintain a controlled environment within the chamber while allowing the introduction and removal of substrates or materials without exposing the chamber to external conditions. For example, the system can further include a separate load lock chamber or antechamber connected to the main chamber through a vacuum sealed door or gate valve. This load lock chamber can serve as a transition area where substrates or materials can be loaded into or removed from the main chamber without disturbing the internal environment of the main chamber where the polymer coating/film is formed. Using a load-lock reactor minimizes the risk of contamination, improves process reproducibility, and enhances overall SACVD system throughput by allowing faster turnaround time between batches and reducing downtime associated with venting and purging the main chamber between each transfer.

In one non-limiting example, the sequence of operations in a load lock system involves the following steps: (1) loading, (2) pumping, (3) transfer, (4) processing, and (5) unloading. During the loading step, a substrate or material is placed inside a load chamber, which is then isolated from the external environment. In the pumping step, the load chamber is evacuated to create a vacuum environment, thereby ensuring that the substrate or material is not exposed to contaminants or atmospheric gases before it is transferred to the main reaction chamber. The transfer step occurs after the load chamber reaches the desired vacuum level. During the transfer step, a vacuum-tight door or gate separating the load chamber from the main reaction chamber is opened, thereby allowing the substrate or material to be transferred into the reaction chamber. In the processing step, the substrate or material undergoes the desired deposition or reaction process inside the main chamber according to the methods described herein. The unloading step occurs after the processing is completed. In the unloading step, the vacuum-tight door or gate is closed, isolating the main chamber from the load chamber, and then the load chamber is evacuated to vacuum again and the substrate or material is removed.

The gas may flow through the reaction chamber in one dimension. The one-dimensional flow may be a flow in which the associated gas flows primarily or entirely in one direction. The one-dimensional flow may also be a laminar flow. As an example of a one-dimensional flow, a one-dimensional flow of a gas may be a flow in which the gas flows entirely in one direction and does not flow in any direction other than that direction. As another example, in some individual cases, the one-dimensional flow of a gas includes a flow that is primarily but not entirely in one direction. For example, the one-dimensional flow may include a small amount of flow in a direction other than the main direction. Such small amounts of flow may account for less than or equal to 50%, less than or equal to 20%, less than or equal to 10% and/or less than or equal to 5% of the one-dimensional flow.

When two or more different types of gases flow through a reaction volume (e.g., two or more types of gases provided from a common source, two or more types of gases provided from different sources, provided from the same source), the different types of gases may together present a one-dimensional flow in a single direction. In other words, all gases together may flow completely in the same direction and/or may together constitute a flow in a direction other than the first direction on one or more of the ranges described in the preceding paragraphs. It is also possible for two or more different types of gases (e.g., provided from different sources, provided from the same source) to have different flow rates from one another. For example, two or more different types of gases may each flow through a reaction volume in a one-dimensional manner, but the directions in which the different types of gases flow may be different from one another. As another example, in some instances, one or more types of gases may exhibit one-dimensional flow and one or more types of gases may not exhibit one-dimensional flow (eg, one or more types of gases may exhibit convective and/or turbulent flow).

In some cases, the reaction chamber includes a relatively low level of air at one or more points in time. This relatively low level of air can occur, for example, when a reaction is being conducted in the reaction chamber (e.g., a reaction to deposit a polymer coating). The reaction chamber may also include a relatively low level of water. This relatively low level of water can occur, for example, when a reaction is being conducted in the reaction chamber (e.g., a reaction to deposit a polymer coating). In some cases, the relative humidity of the reaction chamber can be less than or equal to 0.5%, less than or equal to 0.4%, less than or equal to 0.3%, less than or equal to 0.2%, or less than or equal to 0.1%. The relative humidity of the reaction chamber may be greater than or equal to 0%, greater than or equal to 0.1%, greater than or equal to 0.2%, greater than or equal to 0.3%, or greater than or equal to 0.4%. Combinations of the above-mentioned ranges are also possible (e.g., less than or equal to 0.5% and greater than or equal to 0%).

In some cases, processes (e.g., polymerization, etc.) performed in a reaction chamber of the system may be automated. Such automation may include software that provides instructions for reading various procedures performed (e.g., flow rates and/or types of gases introduced into the reaction system, filament temperatures, substrate temperatures, etc.), and then executing such instructions by directing other system components to perform such instructions. In some cases, the system described herein is maintained at or near its optimal performance. It is also possible to maintain such performance while reducing the work of the operator of the system. This can be achieved by using automation software that records one or more conditions of the system and then alerts the operator when one or more of such conditions indicates that performing one or more maintenance steps will improve system performance. Such system conditions may include the amount of time required to be exposed to a vacuum source in order for the reaction volume to reach a desired pressure, the state of any valves positioned between any source and the reaction volume (e.g., a valve positioned between the vacuum source and the reaction volume, such as a throttling valve), the amount of time since a previous maintenance step, the amount of time the system has been used to deposit a fluorinated polymer coating, the amount of gas that has passed through the system, the amount of time one or more filaments have been resistively heated, etc.

IV. Uses of Surface Activated Chemical Vapor Deposition ( SACVD ) The SACVD methods described above can be used to deposit/form polymer coatings on the surface of a substrate or device with a degree of conformality that would otherwise be difficult or impossible to obtain using other deposition methods. Thus, in some cases, a substrate or device includes a polymer coating formed using the described SACVD method and includes: a polymer coating on at least one surface of the substrate or device; wherein the polymer coating is conformal and has a step coverage of at least 50%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a wafer stacking method; and/or wherein the polymer coating has a microscale conformality of at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a microgroove method. In some cases, such substrates or devices having such conformal polymer coatings thereon can benefit from one or more of the coated surfaces: by adding mechanical protection, by adding electrical insulation, by adding electrical protection, by imparting optical effects, by modifying surface properties, and/or by enhancing bio- or chemical compatibility.

Examples Example 1 : Surface Activated Chemical Vapor Deposition ( SACVD ) of Siloxane-Based Polymer Coatings SACVD synthesis of siloxane-containing polymer coatings was performed in a reaction chamber. The polymer coatings were deposited on three different substrates: (1) silicon wafers; (2) microgroove features; and (3) silicon wafer stacks. These substrates were chosen for their high aspect ratio characteristics at various length scales. The microgroove features were 57 µm deep, 4.5 µm wide, and 1 cm long. As shown in Figures 1A and 1B, the silicon wafer stack was formed from silicon wafers 110 and 120, which were assembled into channels 150 that were 0.5 mm high and 1 inch long.

In the pressure controlled reaction chamber schematically shown in FIG2 , polymer coatings containing siloxane rings are synthesized on these three substrates. As shown in the schematic diagram in FIG2 , the SACVD system includes a reaction chamber 210, a tubular furnace 220, a carrier gas container 230, a carrier gas mass flow controller 235, an initiator container 240, an initiator metering valve 245, a monomer container 250, a pressure converter 260, a throttle valve 270, and a vacuum source 280. All components of the reaction chamber are equipped with heaters that can independently control the temperature of each component. The reaction chamber body has a diameter of 2″ and a length of 24″ and is configured to have temperature control capabilities. Housed within the main body of the reaction chamber is an independent temperature control platform in which the three substrates are placed during the synthesis process. The temperature control platform is 4'' in length, 1.5'' in width, and 0.31'' in thickness.

Prior to use, the monomer and initiator were vacuum purified at room temperature for a total of 2 minutes. The monomer was 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane and the initiator was di-tert-butyl peroxide. The monomer was heated to 80°C to increase its volatility while the initiator was kept at room temperature. Using a dedicated metered needle valve, the monomer gas was delivered to the chamber at a rate of 1.5 sccm and the initiator gas was delivered at a rate of 0.5 sccm. The pressure in the chamber was maintained at 6 Torr using a throttling valve, resulting in a monomer partial pressure of 4.5 Torr and an initiator partial pressure of 1.5 Torr.

The reaction chamber body and sample stage were individually temperature controlled to 110°C and 225°C, respectively. The temperature of the reaction chamber body was selected so that the partial pressure of any gaseous species in the reactor did not exceed the saturation pressure of the reactants at the temperature of the reaction chamber body. This was intended to prevent condensation of gaseous precursors in the chamber. The sample stage temperature was set to a temperature greater than the temperature required to generate free radicals from the di-tertiary butyl peroxide initiator. These conditions were maintained in the chamber for a total elapsed time of 348 minutes to synthesize polymer coatings on three substrates simultaneously. After completion of the polymer deposition process, the monomer container and initiator container were isolated from the reaction chamber, the throttle valves were fully opened, and the platform heater and reaction chamber body heater were turned off.

After the synthesis process was completed, the substrate was removed from the reaction chamber. For the silicon wafer stack, it was disassembled to analyze the coating thickness inside the channel features. The thickness was measured using a Filmetrics MProbe 20 VIS reflectometer. The conformality of the coating on the wafer stack was measured to be 70%. Using the step-cap method, the conformality value was calculated by comparing the thinnest portion of the coating deposited inside the channel feature (870 nm) to the percentage of the coating thickness on the wafer positioned at the channel opening (1240 nm). In comparison, similar testing was performed using induced chemical vapor deposition (iCVD), which produced a conformality of 12% on the same channel features. The conditions for the iCVD used are provided in Table 3 below: Table 3. iCVD Conditions pressure 300 mTorr Monomer (V3D3) flow rate 2.6 sccm Initiator (TBPO) flow rate 0.6 sccm Nitrogen flow rate 4.1 sccm Filament temperature 475 ℃

For the microgroove substrate, it was cut to produce a cross-sectional view of the microgrooves. An exemplary microgroove substrate is shown in FIG1C . Using the cross-section, scanning electron microscopy (SEM) was used to measure the coating thickness at various locations on the sidewalls and bottom of the microgroove substrate; SEM images are not shown. Based on the step-capping method, the conformality of the coating was determined to be 70% and was calculated by comparing the coating thickness at the bottom of the microgroove (656 nm) with the coating thickness at the top of the groove (940 nm). Conformality observed from SEM micrographs showed that the step coverage of the microtrench cross section with the coating produced by induced chemical vapor deposition (iCVD) was 18%, which is significantly lower than the 70% step coverage produced using SACVD.

Prophetic Example : Surface Activated Chemical Vapor Deposition ( SACVD ) of Acrylic-Based Polymer Coatings This example is a theoretical SACVD synthesis process of a copolymer containing linear poly(methacrylic acid) and a divinylbenzene crosslinker coated on the inner diameter of a 1' long stainless steel tube with a 2' OD and a 1.87' ID. The flow and concentration of the chemical precursors will be controlled within the internal dimensions of the tube by attaching a gas delivery manifold and vacuum control system. Seals will be formed directly on the tube to enable a vacuum pump to evacuate the internal volume of the tube. Temperature controlled heaters will be applied to the tube and the connections to the gas delivery manifold and vacuum control system to control the surface temperature of the tube. The manifold and reactor assemblies will be equipped with heaters that can independently control the temperature of each component.

The monomer, crosslinker, and initiator will be vacuum purified at room temperature for a total of 2 minutes before use. In this case, the monomer will be cyclohexyl methacrylate, the crosslinker will be divinylbenzene, and the initiator will be tert-butyl perbenzoate. To increase the volatility of each precursor, the monomer and crosslinker will be heated to 55°C and 65°C, respectively. The initiator will be delivered by bubbling nitrogen as a carrier gas to achieve a total flow rate of 1 sccm. Three silicon wafers will be placed in the tube at positions 3'', 6'', and 9'' from the inlet of the tube. Dedicated metering valves will be set to deliver the monomer and crosslinker at flow rates of 3 sccm and 1 sccm, respectively. The pressure in the chamber is maintained at 6 Torr using a throttling valve, resulting in a monomer partial pressure of 2.25 Torr and a crosslinker partial pressure of 0.75 Torr. The temperature of the tube will be maintained at 150°C. This temperature will be selected to prevent condensation of either gas precursor at the operating pressure and to provide sufficient heat energy to decompose the tributyl peroxybenzoate initiator. These conditions will be maintained in the chamber for a total of 2 hours.

After the synthesis process is completed, the silicon wafer will be analyzed using Fourier transform infrared measurements. Comparison of these spectra with the monomer spectra will indicate successful polymerization, as indicated by a decrease in the unsaturated carbon peak. The spectra from these measurements will be used to confirm the copolymerization of polycyclohexyl methacrylate and polydivinylbenzene, as indicated by the characteristic peaks summarized in Table 4 below. Table 4. Characteristic Peaks Reactants Functional Group Characteristic peak (cm ^-1 ) Polycyclohexyl methacrylate Asymmetric stretching of cyclohexyl CH ₂ 2939, 2861 Polycyclohexyl methacrylate C=O 1714 Polycyclohexyl methacrylate CH 1350-1500 Polydivinylbenzene ^sp3CH 2850 - 3000 Polydivinylbenzene Aromatic = CH 3010 - 3084 Polydivinylbenzene C=C 1630 Polydivinylbenzene =CH 903-990

Example 2 - Selective thermal deposition of SACVD coatings Materials and methods: Poly(1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane) (pV3D3), poly(divinylbenzene) (pDVB), and tertiary butyl styrene (pTBS) were synthesized by selective thermal SACVD using di-tertiary butyl peroxide (TBPO) and tertiary butyl peracetate (TBPA) as initiators. As shown in Figure 3, the polymer materials were synthesized using SACVD in a 0.025 ^m3 reactor.

A silicon wafer sample is placed on a temperature controlled platform fixed inside the reactor and evacuated to a base pressure of 10 mTorr. The platform temperature is then heated to the target temperature before heating the reactor body. A gas stream containing monomer and initiator is then introduced into the chamber to achieve the target pressure. Monomer and initiator are used as purchased without additional purification. A throttling valve is used to maintain the deposition at the target pressure until the desired thickness on the platform is achieved, which is confirmed using reflectometry.

For each deposition, the platform temperature was controlled between 95-215°C while the reactor temperature was maintained between 85-100°C. A monomer flow rate of 3-9 sccm was utilized with an associated initiator flow rate of 1.5-9 sccm. The total chamber pressure was between 2.5-6.0 Torr. Using these conditions, deposition rates of 0.1-3.0 Nm/min were achieved for the growth of different film compositions. Final sample thicknesses of 90-600 nm were achieved and analyzed to confirm the desired polymer structure.

Results: Each polymer coating formed by SACVD was analyzed using Fourier transform infrared spectroscopy to confirm the synthesis of the target material using a Perkin-Elmer System 2000 FT-IR system. Measurements of native silicon wafers were also collected and subtracted from the spectra of the coated wafers. Each spectrum covers the wavenumber range of 500 cm ^{- 1} to 4000 cm ^{- 1} . The spectra were baselined after measurement and normalized to correct for thickness for comparative analysis.

Figure 4 shows the change in wavenumber of IR absorbance values with the pV3D3 coating of Example 2 formed with TBPO or TBPA. The absorbance peak at 1000-1050 cm ^{- 1} is characteristic of Si-O cyclic trimers in pV3D3. The shoulder on the left side of this peak is the result of the vinyl CH absorbance peak near 960 cm ^{- 1} , the presence of which depends on vinyl conversion from initiator radicals due to deposition conditions. The absorbance peaks at 800 cm ^{- 1} and 1260 cm ^{- 1} are characteristic Si- _CH3 bonds in pV3D3. The absorbance peaks from 2870-2960 cm ^{- 1} indicate CH stretching in the methylene carbon backbone and methyl groups of pV3D3. The positive or negative absorbance peaks at 1100-1115 are usually caused by the difference between the background silicon wafer and the native _SiO2 on the measured sample wafer in this FTIR setup.

The spectrum shown in Figure 5 shows the change in wavenumber of the IR absorbance values for the pDVB coating of Example 2 formed with TBPO or TBPA. The absorbance peaks from 690-850 cm ^{- 1} are characteristic of para-substituted and meta-substituted benzene vibrations (DVB monomer is a mixture of para-substituted and meta-substituted isomers). The characteristic C=C aromatic stretching can be seen from the absorbance peaks between 1450-1600 cm ^{- 1} . The absorbance peaks from 2870-2960 cm ^{- 1} indicate the methylene carbon backbone of pDVB and CH stretching from the methyl group incorporated by the TBPO initiator.

The spectrum in Figure 6 shows the variation of IR absorbance values with wavenumber of the pTBS coating of Example 2. The characteristic absorbance peak at 830 cm ^{- 1} indicates para-substituted benzene vibration (TBS monomer is purely para-substituted). The characteristic C=C aromatic stretching is seen from the absorbance peak between 1450-1600 cm ^{- 1} . The absorbance peaks at 2870-2960 cm ^{- 1} indicate CH stretching in the methylene carbon backbone and methyl groups of pTBS, where the methyl peak at 2960 cm ^{- 1} is significantly stronger than the methylene peak compared to the same peaks seen in the pDVB spectrum of Figure 5.

Example 3 - Isothermal and Selective Heated Deposition of SACVD Coatings This example describes the synthesis of pV3D3 using an isothermal SACVD method.

As shown in Figure 3, pV3D3 polymer films were synthesized using SACVD in a 0.0012 ^m3 reactor. The silicon wafer sample and silicon wafer stack were placed on a temperature-controlled platform fixed in the reactor and pumped to a base pressure of 10 mTorr. The configuration of the wafer stack is shown in Figure 1A and Figure 1B.

Methods: For isothermal SACVD deposition, the heating platform (or platforms) and reactor body were heated to a target temperature range between 175°C and 205°C, followed by the introduction of a gas flow containing 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane monomer and di-tert-butyl peroxide initiator. A second set of samples was produced in the same manner by selectively heated SACVD, where only the platform was heated to the target temperature while the reactor body was maintained at 100°C. These deposition conditions maintained chamber pressure using an automated throttle valve until the target thickness was achieved. Polymer thickness was confirmed using reflectometry.

Results: As described in this specification, the thickness of the outer portion of the wafer stack relative to the center was measured for each set of conditions, and the conformality achieved using isothermal and selective deposition is shown in Figure 7.

The coated silicon wafers were also analyzed using Fourier transform infrared spectroscopy (FTIR) to confirm the synthesis of pV3D3. The IR spectrum in Figure 8 shows the variation of IR absorbance values with wavenumber for isothermal coatings of pV3D3 synthesized by the conditions described in Example 2. The absorbance peak at 1000-1050 cm ^{- 1} is characteristic of Si-O cyclic trimers in pV3D3. The shoulder on the left side of this peak is the result of the vinyl CH absorbance peak near 960 cm ^{- 1} , the presence of which depends on vinyl conversion from initiator radicals due to deposition conditions. The absorbance peaks at 800 cm ^{- 1} and 1260 cm ^{- 1} are characteristic Si-CH ₃ bonds in pV3D3. The absorbance peak from 2870-2960 cm ^{- 1} indicates the CH stretching in the methylene carbon backbone and methyl group of pV3D3.

Example 4 - Conformality This example describes the conformality of pV3D3 and pDVB coatings achieved using SACVD, iCVD, and iPECVD methods.

Methods: Using pV3D3 and pDVB as test materials, the conformality of coatings produced by SACVD was compared with iCVD and iPECVD.

For this example, SACVD coatings were deposited on the test substrate using the conditions described above in Example 2. The iCVD coatings were synthesized using a 0.0026 m ³ reactor, as shown in Figure 9, while the iPECVD coatings were synthesized in a 0.210 m ³ reactor, as shown in Figure 10.

For iCVD, a silicon wafer sample is placed on a temperature-controlled platform at the base of the reactor. A heated filament array is placed above the sample and then connected to a power supply via a vacuum feedthrough. The reaction chamber is evacuated to a base pressure of 40 mTorr. The platform temperature is controlled to a temperature between 25°C and 50°C. The reaction chamber walls are heated to 70°C. The monomer and initiator feed lines are heated to 100°C. A gas stream containing the monomer and initiator is then introduced into the chamber and pressurized to the target pressure using a throttle valve. The monomer and initiator are used as purchased without additional purification. The filament temperature is controlled by setting the voltage on the Variac power supply, which is pre-calibrated to determine the filament temperature set point. The filament is turned on and the deposit is maintained at the target pressure until the desired thickness is achieved, which is confirmed using profilometry.

For iPECVD, silicon wafer samples are suspended vertically on an aluminum plate in the reaction chamber below the showerhead gas diffuser and above the electrode. The reaction chamber is evacuated to a base pressure of 4 mTorr. Monomers, initiators, and dilution gases are introduced evenly across the width of the chamber using a showerhead that spans the entire electrode area. Monomers and initiators are used as purchased without additional purification. The chamber is pressurized to the target pressure using a throttle valve. Subsequently, initiator activation is performed using RF plasma while maintaining the target pressure until the desired thickness is achieved, which is confirmed using interferometry.

The conformality of the coating was also measured on the micro-trench to evaluate the conformality of features on the order of a single micron. The geometry of the micro-trench is shown in Figure 11. In this case, the conformality was determined by comparing the coating thickness at the top of the micro-trench to the coating thickness at the bottom of the micro-trench.

After deposition, the microgrooved samples were fractured after coating using a diamond tip scriber to obtain clean edges for imaging by scanning electron microscopy. The samples were then mounted at 90° to a stub with carbon tape, with the exposed edge of the microgrooves facing up, and colloidal silver was sprayed on the edge of the sample to the sample holder to minimize charge accumulation from the electron beam on the polymer film surface. The accelerating voltage of the electron beam was set to 1 kV for imaging and did not exceed 3 kV during the imaging process to prevent damage to the polymer.

Results: To evaluate conformality on substrates with features on the order of hundreds of microns, wafer stacks as described in Example 3 were coated and evaluated by comparing the coating thickness at the center of the wafer stack to the coating thickness on a silicon wafer positioned adjacent to the wafer stack. A comparison of the conformality achieved on the wafer stack by the various processes is summarized in Table 5 below. Table 5. Summary of conformality achieved on wafer stacks using SACVD, iCVD, and iPECVD. Conformality on wafer stacking Chemical substances SACVD selective deposition iC iPECVD pV3D3 and TBPO 54% 2 % 1% pV3D3 and TBPA 55 % 2 % -- pDVB and TBPO 68 % 2% --

An example of thickness analysis using SEM micrographs of microgrooves coated with pV3D3 synthesized using TBPO was performed (image not shown), and a summary of the conformality achieved on the microgrooves by various processes is shown below in Table 6. Table 6. Summary of the conformality achieved on microgrooves using SACVD, iCVD, and iPECVD. Conformity on microgrooves Chemical substances Selective Heating SACVD iC iPECVD pV3D3 and TBPO 73.4 % 23.2 % 5% pDVB and TBPO 80.2 % 6.2 % --

Example 5 - Selection of Process Conditions for Forming Defect-Free Polymer Coatings / Films This example describes various film defects that may occur depending on the process conditions, which may fall outside the desired range selected for SACVD deposition.

Methods: As shown in Figure 3, pV3D3 coatings were synthesized under two sets of conditions using a 0.0012 ^m3 reactor. The resulting coatings were then imaged using a SEM microscope to evaluate their morphology. A summary of the conditions used is listed in Table 7. Condition 4A is a deposition example in which the ratio of the partial pressure in the coldest part of the reactor to the saturation pressure never exceeds 1, thereby avoiding reactant condensation. In contrast, Condition 4B involves a gradual decrease in the initiator flow rate from 3 sccm to 0 sccm, such that the ratio of the partial pressure in the coldest part of the reactor to the saturation pressure exceeds 1, thereby allowing reaction condensation. Table 7. Summary of deposition conditions used to produce various coating morphologies. condition 4A 4B Platform temperature ( ℃ ) 205 160 Reactor temperature ( ℃ ) 100 85 Single V3D3 V3D3 Monomer flow rate (sccm) 3 10 Initiator flow rate (sccm) 1 3-0 Initiator TBPO TBPO Pressure (Torr) 4.0 10 Coating form Smooth and dense coating Bubble formation

Results: SEM micrographs of the resulting coating morphology (not shown) show that a smooth, dense coating was produced under condition 4A, and that bubbles were formed under condition 4B. Thus, depending on the choice of process conditions, the film morphology can exhibit a large number of nodular defects in the film deposited under condition 4B.

Example 6 - Effect of Process Setup and Reactor Geometry on Coating Morphology This example describes the effect of the proximity of the heated surface area using SACVD.

Method: Using a custom sample platform, deposition was performed with two separate platforms controlled to a surface temperature of 215° C. Custom sample platform not shown.

A gas profile containing a V3D3 partial pressure of 4.5 Torr and a TBPO partial pressure of 1.5 Torr was maintained across four discrete depositions, with the spacing between shelves varying from 1 in. to 4 in. The deposition rates on the top and bottom shelves were recorded and confirmed using reflectometry.

Results: A summary of the deposition rates is shown in Table 8. Within the range of shelf spacing, no significant changes between deposition rates were detected between the top shelf and the bottom shelf until the spacing was reduced to 1". At 1" spacing, the bottom shelf exhibited significantly higher deposition rates compared to the top shelf. As described in Example 3 above, two of the depositions also included wafer stacks. Measurements on these wafer stacks showed that conformality decreased from 51% to 38% when reducing the platform spacing distance from 4" to 1". Morphological changes were also observed with decreasing platform spacing, where the formation of particles and coating bubbles increased with decreasing platform spacing. Table 8. Deposition rates measured at different spacing distances on the top and bottom shelves. Platform spacing ( inches ) Top shelf deposition rate (nm/min) Bottom shelf deposition rate (nm/min) Bottom Shelf Wafer Stacking Conformality Coating form 4 2.9 2.8 51 % Smooth and dense coating 3 2.9 2.9 -- Smooth and dense coating 2 2.7 2.7 -- Slight particle/bubble formation 1 2.8 3.8 38 % Particle/bubble formation

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention belongs. The publications cited herein and the materials for which they are cited are expressly incorporated by reference.

Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

100: silicon wafer stack 110: top wafer 120: bottom wafer 130a: side strips 130b: side strips 140: adhesive 150: channel features 152: openings 200: micro-grooved substrate, SACVD system 210: micro-grooves, reaction chamber 220: bottom section, tubular furnace 230: carrier gas container 230a: side wall 230b: side wall 235: carrier gas mass flow controller 240: initiator container 245: initiator metering valve 250: single body container 260: pressure converter 270: throttle valve 280: Vacuum source 300: SACVD reactor 310: Initiator container 320: Single body container 330: Initiator metering valve 340: Single body metering valve 350: Reaction chamber 360: Temperature control platform 370: Pressure converter 380: Throttle valve 390: Vacuum pump 400: iCVD reactor 410: Single body container 420: Initiator container 430: Single body metering valve 440: Initiator metering valve 450: Temperature control platform 460: Filament array 470: Pressure converter 480: Throttle valve 490: Vacuum pump 500: iPECVD reactor 510: single body container 520: initiator container 530: single body metering valve 540: initiator metering valve 550: showerhead gas diffuser 560: sample rack panel 570: electrode 580: pressure converter 590: throttle valve 595: vacuum pump 597: inert (argon) storage tank

Non-limiting embodiments are described by way of example with reference to the accompanying drawings, which are schematic and not necessarily drawn to scale. In the figures, each identical or nearly identical component depicted is generally represented by a single numeral. For purposes of clarity, not every component is labeled or shown in every figure, and the figures are not necessary for a person of ordinary skill in the art to understand the figures. FIG. 1A shows a non-limiting illustration of an exemplary silicon wafer stack 100. The exemplary wafer stack includes a top wafer 110 and a bottom wafer 120 separated by two side strips 130a, 130b, which establish a channel feature 150 having an opening 152, which is used to evaluate the conformality of a polymer coating deposited therein. Adhesive 140 holds the stack of silicon wafers together. FIG . 1B shows a cross-sectional view of the exemplary silicon wafer stack depicted in FIG. 1A. FIG. 1C shows a non-limiting depiction of a cross-sectional view of a micro-groove substrate 200 containing micro-grooves 210 including a bottom portion 220 and sidewalls 230a and 230b. FIG. 2 shows a non-limiting schematic diagram of an exemplary SACVD system for synthesizing a conformal polymer coating. This exemplary SACVD system 200 includes a reaction chamber 210, a tubular furnace 220, a carrier gas container 230, a carrier gas mass flow controller 235, an initiator container 240, an initiator metering valve 245, a monomer container 250, a pressure converter 260, a throttle valve 270, and a vacuum source 280. FIG3 shows a non-limiting schematic diagram of an exemplary SACVD reactor 300 having the following components: an initiator container 310, a monomer container 320, an initiator metering valve 330, a monomer metering valve 340, a reaction chamber 350, a temperature control platform 360, a pressure converter 370, a throttle valve 380, and a vacuum pump 390. Figure 4 shows infrared (IR) spectra of pV3D3 polymers synthesized at different temperatures using SACVD with different initiator chemistries. Figure 5 shows infrared (IR) spectra of pDVB polymers synthesized using SACVD using different initiators. Figure 6 shows infrared (IR) spectra of pTBS synthesized using SACVD using initiator TBPA. Figure 7 shows a graph comparing the conformality achieved using isothermal deposition and selective deposition, with the highest points for selective deposition and the lowest points for isothermal deposition at 175°C, 185°C, and 205°C, respectively. Figure 8 shows an infrared (IR) spectrum of pV3D3 synthesized using SACVD using isothermal heating. 9 shows a non-limiting schematic diagram of an iCVD reactor 400 having the following components: a monomer container 410, an initiator container 420, a monomer metering valve 430, an initiator metering valve 440, a temperature control platform 450, a filament array 460, a pressure converter 470, a throttle valve 480, and a vacuum pump 490. Figure 10 shows a non-limiting schematic diagram of an iPECVD reactor 500 having the following components: a monomer container 510, an initiator container 520, a monomer metering valve 530, an initiator metering valve 540, a showerhead gas diffuser 550, a sample rack panel 560, an electrode 570, a pressure converter 580, a throttle valve 590, a vacuum pump 595, and an inert (argon) tank 597. Figure 11 shows a non-limiting diagram depicting the geometry of the micro-grooves.

200:SACVD system

210: Reaction room

220: Tubular furnace

230:Carrier gas container

235:Carrier gas mass flow controller

240: Initiator container

245: Igniter metering valve

250: Single container

260: Pressure converter

270:Throttle valve

280: Vacuum source

Claims (93)

A method for forming a polymer coating on at least one substrate or device, the method comprising the steps of: (i) placing the at least one substrate or device in a reaction chamber; (ii) sealing and purging the reaction chamber under vacuum; (iii) wherein the reaction chamber is at a triggering temperature sufficient to activate one or more gaseous initiators; wherein one or more surfaces of the at least one substrate or device have a surface temperature equal to or substantially equal to the triggering temperature; and (iv) flowing one or more gaseous monomers, the one or more gaseous initiators, and optionally one or more carrier gases into the reaction chamber to form the polymer coating on at least a portion of the one or more surfaces of the at least one substrate or device; wherein the partial pressure of the one or more gaseous monomers is sufficient to form the polymer coating on the portion of the one or more surfaces of the at least one substrate or device at the surface temperature; and wherein the surface temperature during step (iv) is sufficient to prevent the one or more gaseous monomers or the one or more gaseous initiators from exceeding their saturation pressure at the surface temperature, as the case may be. A method for forming a polymer coating on at least one substrate or device, the method comprising the following steps: (i) placing the at least one substrate or device on a platform within a reaction chamber; wherein the reaction chamber and/or its components and the platform are independently temperature controlled; (ii) sealing and purging the reaction chamber under vacuum; (iii) wherein the platform is at a triggering temperature sufficient to activate one or more gaseous initiators; wherein one or more surfaces of the at least one substrate or device have a surface temperature equal to or substantially equal to the triggering temperature; and (iv) flowing one or more gaseous monomers, the one or more gaseous initiators and, if present, one or more carrier gases into the reaction chamber to form the polymer coating on at least a portion of the one or more surfaces of the at least one substrate or device; wherein the reaction chamber and/or its components are independently heated to a reaction chamber temperature, wherein during step (iv) the reaction chamber temperature is below the initiation temperature and the surface temperature; optionally wherein the components comprise a wall of the reaction chamber; wherein the partial pressure of the one or more gaseous monomers is sufficient to form the polymer coating on the portion of the one or more surfaces of the at least one substrate or device at the surface temperature; and optionally wherein the reaction chamber temperature during step (iv) is sufficient to prevent the one or more gaseous monomers or the one or more gaseous initiators from exceeding their saturation pressure at the reaction chamber temperature. A method as in any one of claims 1 to 2, wherein the period between step (i) and step (iii) is a dwell time during which the temperature of the surface of the substrate increases to the surface temperature, and wherein the dwell time is at least about 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 minutes. The method of any one of claims 1 to 3, wherein step (iv) is performed for a period of time ranging from about 30 to 800 minutes. A method as claimed in any one of claims 1 to 4, wherein after step (iv), the reaction chamber is purged and cooled to room temperature, and then the reaction chamber is vented. The method of any one of claims 1 to 5, wherein the polymer coating is formed under a pressure ranging from about 1 to 760,000 mTorr. The method of any one of claims 1 to 5, wherein the polymer coating is formed under a pressure ranging from about 100 mTorr to 10 Torr. A method as in any one of claims 1 to 7, wherein during step (iv), the one or more gaseous monomers, the one or more gaseous initiators and/or the one or more carrier gases flow continuously through the reaction chamber. A method as in any one of claims 1 to 7, wherein during step (iv), the one or more gaseous monomers, the one or more gaseous initiators and/or the one or more carrier gases flow discontinuously through the reaction chamber. The method of claim 2, wherein the at least one substrate or device comprises a plurality of substrates and/or devices, and each of the plurality of substrates and/or devices is independently placed on a separate temperature-controlled platform as appropriate. A method as in any one of claims 1 to 10, wherein the at least one polymer coating is formed continuously or semi-continuously on the at least one substrate or device. A method as claimed in any one of claims 1 to 11, wherein step (iv) is repeated at least once or more times with the same or different types of the one or more gaseous monomers and the one or more gaseous initiators to form a polymer coating comprising a plurality of layers; wherein when the type of the one or more gaseous initiators is changed, step (iii) is repeated before the at least one or more times as appropriate. The method of claim 12, wherein at least one of the plurality of layers is formed from a polymer that is different from a polymer forming at least one other layer of the plurality of layers. A method as in any one of claims 1 to 13, wherein the polymer coating is formed by vinyl polymerization, wherein the one or more gaseous monomers include monomers having at least one vinyl moiety thereon. The method of claim 14, wherein the vinyl polymerization is a free radical vinyl polymerization. A method as claimed in any one of claims 1 to 15, wherein the at least one polymer coating is formed from one or more polymers, copolymers and/or one or more cross-linked polymers, and this formation is achieved by flowing at least two different types of the one or more gaseous monomers during step (iv); and wherein when forming the cross-linked polymers, one or more gaseous cross-linking agents are further flowed during step (iv) as appropriate. A method as in any one of claims 1 to 16, wherein the one or more gaseous monomers are selected from the group consisting of: acrylate monomers, methacrylate monomers, vinyl-containing monomers, parylene monomers, ethylene oxide-based monomers, and combinations thereof. The method of claim 17, wherein: The acrylate monomers are selected from the group consisting of: hydroxyethyl acrylate, ethylene glycol diacrylate, 1H,1H,2H,2H-perfluorodecyl acrylate, and combinations thereof; The methacrylate monomers are selected from the group consisting of: hydroxyethyl methacrylate, ethylene glycol dimethacrylate, 1H,1H,2H,2H-perfluorodecyl methacrylate, and combinations thereof; and/or The vinyl-containing monomers are selected from the group consisting of: 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, divinylbenzene, 4-vinylpyridine, styrene, 1H,1H,2H-perfluoro-1-dodecene, di(ethylene glycol) divinyl ether, and combinations thereof. The method of claim 17, wherein the parylene monomers are selected from the group consisting of [2,2] parylene, dichloro-[2,2]-parylene, 1,1,2,2,9,9,10,10-octafluoro[2.2] parylene and 4,5,7,8,12,13,15,16-octafluoro[2.2] parylene. The method of claim 17, wherein the ethylene oxide-based monomer is hexafluoropropylene oxide. A method as claimed in any one of claims 1 to 20, wherein the initiation temperature ranges from about 50°C to about 400°C. The method of any one of claims 1 to 20, wherein the initiation temperature ranges from about 100°C to about 250°C. A method as in any of claims 1 to 20, wherein the initiation temperature is selected to provide a deposition rate of the polymer coating of at least 0.5 nm/min, optionally wherein the initiation temperature is also sufficiently low to prevent defects in the polymer coating. A method as in any one of claims 1 to 23, wherein the one or more gaseous initiators include at least one free radical thermal initiator and/or at least one ionic (i.e., cationic or anionic) thermal initiator. The method of claim 24, wherein the at least one free radical thermal initiator is selected from the group consisting of: peroxide-based initiators, poly(p-xylene)-based initiators, ethylene oxide-based initiators, and combinations thereof. The method of claim 25, wherein the peroxide-based initiator is selected from the group consisting of tertiary butyl hydroperoxide, isopropylbenzene hydroperoxide, di-tertiary butyl peroxide, diisopropylbenzene peroxide, benzoyl peroxide, ammonium persulfate, and combinations thereof. The method of claim 24, wherein the at least one free radical thermal initiator is an azonitrile based initiator. The method of claim 27, wherein the azonitrile-based initiator is selected from the group consisting of azobisisobutyronitrile, 2,2'-azobis[2-(2-imidazolin-2-yl)-propane] dihydrochloride, and combinations thereof. The method of claim 24, wherein the at least one ion thermal initiator is selected from the group consisting of dicyandiamide, cyclohexyl toluenesulfonate, (4-hydroxyphenyl)-dimethylcorbyl hexafluorophosphate, diphenyl(methyl)corbyl tetrafluoroborate, benzyl(4-hydroxyphenyl)-methylcorbyl hexafluoroantibonate, (4-hydroxyphenyl)methyl-(2-methylbenzyl)corbyl hexafluoroantibonate, triphenylcorbyl nonafluorobutanesulfonate, and combinations thereof. The method of any of claims 1 to 29, wherein the polymer coating formed on the one or more surfaces of the at least one substrate or device has a conformality of at least about 40% as determined by a wafer stacking method. The method of claim 30, wherein the conformality of the at least one substrate or device is at least about 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or 90% as measured by the wafer stacking method. The method of any of claims 1 to 29, wherein the polymer coating formed on the one or more surfaces of the at least one substrate or device has a microscale conformality of at least about 50% as determined by a microtrench method. The method of claim 32, wherein the microscale conformality of the at least one substrate or device is at least about 60%, 65%, 70%, 75%, 80% or 90% as measured by the microtrench method. A method as claimed in any one of claims 1 to 33, wherein the method further comprises a step of reducing the organic content of the polymer coating after step (iv), such as by applying an annealing step. The method of claim 34, wherein the annealing step occurs during the flowing step (iv). The method of claim 34, wherein the annealing step occurs after the flowing step (iv). The method of claim 36, further comprising, prior to the annealing step, transferring the substrate or material having the polymer coating thereon to another chamber in which the annealing step is performed. A method as in any of claims 34 to 37, wherein the annealing step occurs at a temperature in the range of about 200°C to 800°C, 200°C to 750°C, 200°C to 700°C, 200°C to 650°C, 200°C to 600°C, 200°C to 550°C, 200°C to 500°C, 200°C to 450°C, 200°C to 400°C, 200°C to 350°C or 200°C to 250°C. A method as in any one of claims 34 to 38, wherein the annealing step is performed under a process gas selected from the group consisting of: nitrogen, argon, ammonia, hydrogen, forming gas and combinations thereof; and wherein the process gas does not contain or substantially does not contain oxygen ( _O2 ) gas; or wherein the process gas comprises oxygen ( _O2 ) gas or air. The method of any one of claims 34 to 39, wherein the annealing step occurs for a period of time ranging from about 5 minutes to about 3 hours. A method as in any one of claims 34 or 36 to 40, wherein the annealing step occurs after step (iv), and wherein after the annealing step, the density of the polymer coating is greater than the polymer coating formed in step (iv). A method as in any of claims 34 or 36 to 40, wherein the annealing step occurs after step (iv), and wherein after the annealing step, the mass of the polymer coating is about 80%, 70%, 60%, 50%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5% or less of the mass of the polymer coating formed in step (iv). A method as claimed in any one of claims 1 to 42, wherein the polymer coating is free of or substantially free of pinholes and/or defects. A method as in any of claims 1 to 43, wherein the method is performed without using hot filament heating, resistive heating, induction heating, radiation heating, electron beam, laser exposure, radio frequency (RF), microwave excitation, ultraviolet (UV), infrared (IR) radiation and/or gamma radiation to initiate or cause the decomposition of the one or more gaseous initiators or gaseous monomers. The method of any one of claims 1 to 44, wherein the at least one substrate or device is treated prior to step (i), wherein the treatment is selected from the group consisting of: silane deposition, electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure, and combinations thereof. A method as in any of claims 1 to 45, further comprising, after step (iv), treating the polymer coating on the at least one substrate or device with a treatment selected from the group consisting of: electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure, and combinations thereof. A substrate or device comprising: A polymer coating on at least one surface of the substrate or device; wherein the polymer coating has a conformality of at least 40%, at least 45%, at least 50%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a wafer stacking method; and/or wherein the polymer coating has a microscale conformality of at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a microgroove method. A substrate or device comprising: A polymer coating on at least one surface of the substrate or device; wherein the polymer coating has a conformality of at least 40%, at least 45%, at least 50%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a wafer stacking method; and/or wherein the polymer coating has a microscale conformality of at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a microgroove method; wherein the substrate or device is made by the method of any one of claims 1 to 46. A substrate or device as claimed in claim 48, wherein the polymer coating has a conformality of at least 50%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a wafer stacking method; and/or wherein the polymer coating has a microscale conformality of at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% or more as determined by a microgroove method. A method for forming a polymer coating on a reactor surface, the method comprising the steps of: (i) sealing and purging the reactor under vacuum; (ii) wherein the reaction chamber is at an initiation temperature sufficient to activate one or more gaseous initiators; wherein one or more surfaces of the reactor have a surface temperature equal to or substantially equal to the initiation temperature; and (iii) flowing one or more gaseous monomers, one or more gaseous initiators and, if applicable, one or more carrier gases into the reactor to form a polymer coating on at least a portion of the one or more surfaces of the reactor. The method of claim 50, wherein (ii) comprises heating for a period of at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or 60 minutes prior to step (iii). The method of any one of claims 50 to 51, wherein step (iii) is performed for a period of time ranging from about 30 to 800 minutes. A method as claimed in any one of claims 50 to 52, wherein after step (iii), the reactor is purged and cooled to room temperature and then vented. The method of any of claims 50 to 53, wherein the polymer coating is formed at a pressure ranging from about 1 to 760,000 mTorr. The method of any one of claims 50 to 53, wherein the polymer coating is formed at a pressure ranging from about 100 mTorr to 10 Torr. A method as in any one of claims 50 to 55, wherein during step (iii), the one or more gaseous monomers, the one or more gaseous initiators and/or the one or more carrier gases flow continuously through the reactor. A method as in any of claims 50 to 55, wherein during step (iii), the one or more gaseous monomers, the one or more gaseous initiators and/or the one or more carrier gases flow discontinuously through the reactor. A method as in any of claims 50 to 57, wherein the at least one polymer coating is formed continuously or semi-continuously on the one or more surfaces of the reactor. A method as claimed in any one of claims 50 to 57, wherein step (iii) is repeated at least once or more times with the same or different types of the one or more gaseous monomers and the one or more gaseous initiators to form a polymer coating comprising a plurality of layers; wherein when the type of the one or more gaseous initiators is changed, step (iii) is repeated before the at least one or more times as appropriate. The method of claim 59, wherein at least one of the plurality of layers is formed from a polymer that is different from a polymer forming at least one other layer of the plurality of layers. The method of any of claims 50 to 60, wherein the polymer coating is formed by vinyl polymerization, wherein the one or more gaseous monomers include monomers having at least one vinyl moiety thereon. The method of claim 61, wherein the vinyl polymerization is a free radical vinyl polymerization. A method as in any of claims 50 to 62, wherein the at least one polymer coating is formed from one or more polymers, copolymers and/or one or more cross-linked polymers, and this formation is achieved by flowing at least two different types of the one or more gaseous monomers during step (iii); and wherein when forming the cross-linked polymers, one or more gaseous cross-linking agents are further flowed during step (iii) as appropriate. A method as in any of claims 50 to 63, wherein the one or more gaseous monomers are selected from the group consisting of acrylate monomers, methacrylate monomers, vinyl-containing monomers, poly(p-xylylene) monomers, ethylene oxide-based monomers, and combinations thereof. The method of claim 64, wherein: The acrylate monomers are selected from the group consisting of hydroxyethyl acrylate, ethylene glycol diacrylate, 1H,1H,2H,2H-perfluorodecyl acrylate, and combinations thereof; The methacrylate monomers are selected from the group consisting of hydroxyethyl methacrylate, ethylene glycol dimethacrylate, 1H,1H,2H,2H-perfluorodecyl methacrylate, and combinations thereof; and/or The vinyl-containing monomers are selected from the group consisting of 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, divinylbenzene, 4-vinylpyridine, styrene, 1H,1H,2H-perfluoro-1-dodecene, di(ethylene glycol) divinyl ether, and combinations thereof. The method of claim 64, wherein the parylene monomers are selected from the group consisting of [2,2] parylene, dichloro-[2,2]-parylene, 1,1,2,2,9,9,10,10-octafluoro[2.2] parylene and 4,5,7,8,12,13,15,16-octafluoro[2.2] parylene. The method of claim 64, wherein the ethylene oxide-based monomer is hexafluoropropylene oxide. A method as claimed in any one of claims 50 to 67, wherein the initiation temperature ranges from about 50°C to about 400°C. The method of any one of claims 50 to 67, wherein the initiation temperature ranges from about 100°C to about 250°C. A method as in any of claims 50 to 67, wherein the initiation temperature is selected to provide a deposition rate of the polymer coating of at least 0.5 nm/min, optionally wherein the initiation temperature is also sufficiently low to prevent defects in the polymer coating. A method as in any of claims 50 to 70, wherein the one or more gaseous initiators include at least one free radical thermal initiator and/or at least one ionic (i.e., cationic or anionic) thermal initiator. The method of claim 71, wherein the at least one free radical thermal initiator is selected from the group consisting of: peroxide-based initiators, poly(p-xylene)-based initiators, ethylene oxide-based initiators, and combinations thereof. The method of claim 72, wherein the peroxide-based initiator is selected from the group consisting of tertiary butyl hydroperoxide, isopropylbenzene hydroperoxide, di-tertiary butyl peroxide, diisopropylbenzene peroxide, benzoyl peroxide, ammonium persulfate, and combinations thereof. The method of claim 71, wherein the at least one free radical thermal initiator is an azonitrile based initiator. The method of claim 74, wherein the azonitrile-based initiator is selected from the group consisting of azobisisobutyronitrile, 2,2'-azobis[2-(2-imidazolin-2-yl)-propane] dihydrochloride, and combinations thereof. The method of claim 71, wherein the at least one ion thermal initiator is selected from the group consisting of dicyandiamide, cyclohexyl toluenesulfonate, (4-hydroxyphenyl)-dimethylcorbyl hexafluorophosphate, diphenyl(methyl)corbyl tetrafluoroborate, benzyl(4-hydroxyphenyl)-methylcorbyl hexafluoroantibonate, (4-hydroxyphenyl)methyl-(2-methylbenzyl)corbyl hexafluoroantibonate, triphenylcorbyl nonafluorobutanesulfonate, and combinations thereof. A method as in any of claims 50 to 76, wherein the polymer coating formed on the one or more surfaces of the at least one substrate or device has a conformality of at least about 50% as determined by a wafer stacking method. The method of claim 77, wherein the conformality is at least about 60%, 65%, 70%, 75%, 80% or 90% as measured by the wafer stacking method. The method of any of claims 50 to 76, wherein the polymer coating formed on the one or more surfaces of the at least one substrate or device has a microscale conformality of at least about 50% as measured by a microtrench method. The method of claim 79, wherein the microscale conformality is at least about 65%, 70%, 75%, 80% or 90% as measured by the microgroove method. A method as in any one of claims 50 to 80, wherein the method further comprises an annealing step. The method of claim 81, wherein the annealing step occurs during the flowing step (iv). The method of claim 81, wherein the annealing step occurs after the flowing step (iv). The method of claim 83, further comprising, prior to the annealing step, transferring the substrate or material having the polymer coating thereon to another chamber in which the annealing step is performed. A method as in any of claims 81 to 84, wherein the annealing step occurs at a temperature in the range of about 200°C to 800°C, 200°C to 750°C, 200°C to 700°C, 200°C to 650°C, 200°C to 600°C, 200°C to 550°C, 200°C to 500°C, 200°C to 450°C, 200°C to 400°C, 200°C to 350°C or 200°C to 250°C. A method as in any one of claims 81 to 85, wherein the annealing step is performed under a process gas selected from the group consisting of: nitrogen, argon, ammonia, hydrogen, forming gas and combinations thereof; and wherein the process gas does not contain or substantially does not contain oxygen ( _O2 ) gas; or wherein the process gas comprises oxygen ( _O2 ) gas or air. The method of any one of claims 81 to 86, wherein the annealing step occurs for a period of time ranging from about 5 minutes to about 3 hours. A method as in any one of claims 81 or 83 to 87, wherein the annealing step occurs after step (iv), and wherein after the annealing step, the density of the polymer coating is greater than the polymer coating formed in step (iv). A method as in any of claims 81 or 83 to 87, wherein the annealing step occurs after step (iv), and wherein after the annealing step, the mass of the polymer coating is about 50%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5% or less than the mass of the polymer coating formed in step (iv). A method as in any one of claims 50 to 89, wherein the polymer coating is free of or substantially free of pinholes and/or defects. A method as in any of claims 50 to 90, wherein the method is performed without using hot filament heating, resistive heating, induction heating, radiation heating, electron beam, laser exposure, radio frequency (RF), microwave excitation, ultraviolet (UV), infrared (IR) radiation and/or gamma radiation to initiate or cause the decomposition of the one or more gaseous initiators or gaseous monomers. A method as claimed in any one of claims 50 to 91, wherein the one or more surfaces of the reactor are treated prior to step (i), wherein the treatment is selected from the group consisting of: silane deposition, electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure and combinations thereof. A method as in any of claims 50 to 92, further comprising, after step (iii), treating the polymer coating on the reactor with a treatment selected from the group consisting of: electron beam, IR radiation, gamma radiation, plasma exposure, thermal treatment, laser exposure, and combinations thereof.