WO2025212333A1

WO2025212333A1 - Cryogenic chuck for narrow ion angular spread in substrate processing systems

Info

Publication number: WO2025212333A1
Application number: PCT/US2025/021506
Authority: WO
Inventors: Juline Shoeb; Alexander Miller PATERSON
Original assignee: Lam Research Corp
Current assignee: Lam Research Corp
Priority date: 2024-04-01
Filing date: 2025-03-26
Publication date: 2025-10-09
Anticipated expiration: 2026-10-01

Abstract

An example substrate processing system includes a processing chamber including a window, a substrate support arranged in the processing chamber, configured to support a substrate on an upper surface thereof, at least one radio frequency (RF) source configured to supply an RF signal to one or more coils, at least one of a liquid nitrogen source or a liquid helium source arranged to supply at least one of liquid nitrogen or liquid helium to the substrate support, and a controller configured to strike plasma by supplying RF power from the at least one radio frequency (RF) source to the one or more coils, and to supply the at least one of liquid nitrogen or liquid helium to the substrate support to control a temperature of the substrate support at or below a target cooling temperature value to control an ion angular spread during etching of the substrate.

Description

CRYOGENIC CHUCK FOR NARROW ION ANGULAR SPREAD IN SUBSTRATE

PROCESSING SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/572,884, filed on April 1 , 2024. The entire disclosure of the above application is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to substrate processing systems including cryogenic chucks to reduce ion angular spread via cold plasmas.

BACKGROUND

[0003] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] Substrate processing systems may be used to treat substrates such as semiconductor wafers. Example processes that may be performed on a substrate include, but are not limited to, chemical vapor deposition (CVD), atomic layer deposition (ALD), conductor etch, dielectric etch, and/or other etch, deposition, or cleaning processes. A substrate may be arranged on a substrate support, such as a pedestal, an electrostatic chuck (ESC), etc. in a processing chamber of the substrate processing system. During etching, etch gas mixtures including one or more gases may be introduced into the processing chamber and plasma may be used to initiate chemical reactions.

[0005] The substrate support may include a ceramic layer arranged to support a substrate. For example, the substrate may be clamped to the ceramic layer during processing. The substrate support may include an edge ring arranged to surround an outer perimeter of the ceramic layer and the substrate. SUMMARY

[0006] An example substrate processing system includes a processing chamber including a window, a substrate support arranged in the processing chamber, configured to support a substrate on an upper surface thereof, at least one radio frequency (RF) source configured to supply an RF signal to one or more coils, at least one of a liquid nitrogen source or a liquid helium source arranged to supply at least one of liquid nitrogen or liquid helium to the substrate support, and a controller configured to strike plasma by supplying RF power from the at least one radio frequency (RF) source to the one or more coils, and to supply the at least one of liquid nitrogen or liquid helium to the substrate support to control a temperature of the substrate support at or below a target cooling temperature value to control an ion angular spread during etching of the substrate.

[0007] In some examples, the at least one of the liquid nitrogen source or the liquid helium source includes the liquid nitrogen source, and the controller is configured to control the liquid nitrogen source to supply liquid nitrogen to the substrate support to control the temperature of the substrate support at or below the target cooling temperature value.

[0008] In some examples, the at least one of the liquid nitrogen source or the liquid helium source includes the liquid helium source, and the controller is configured to control the liquid helium source to supply liquid helium to the substrate support to control the temperature of the substrate support at or below the target cooling temperature value.

[0009] In some examples, the at least one of the liquid nitrogen source or the liquid helium source includes both the liquid nitrogen source and the liquid helium source, and the controller is configured to control the liquid nitrogen source to supply liquid nitrogen to the substrate support, and to control the liquid helium source to supply liquid helium to the substrate support, to control the temperature of the substrate support at or below the target cooling temperature value.

[0010] In some examples, the controller is configured to supply the liquid nitrogen and the liquid helium to the substrate support at a same time. In some examples, the controller is configured to supply the liquid nitrogen and the liquid helium to the substrate support in alternating time periods. [0011] In some examples, the target cooling temperature value for the substrate support is less than or equal to negative twenty degrees Celsius. In some examples, the target cooling temperature value for the substrate support is negative twenty degrees Celsius. In some examples, the target cooling temperature value for the substrate support is less than or equal to negative 60 degrees Celsius.

[0012] In some examples, the target cooling temperature value for the substrate support is less than or equal to negative 160 degrees Celsius. In some examples, the target cooling temperature value for the substrate support is less than or equal to negative 200 degrees Celsius.

[0013] In some examples, the controller is configured to receive a sensed temperature of the substrate support, supply the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being greater than the target cooling temperature value, and stop supplying the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being less than the target cooling temperature value.

[0014] In some examples, the controller is configured to receive an etching characteristic value indicative of an etching result condition of the substrate, and reduce the target cooling temperature value in response to the etching characteristic value failing to satisfy etching characteristic criteria.

[0015] In some examples, the etching characteristic criteria includes at least one of an etching critical dimension of the substrate or a mask selectivity value of the substrate. In some examples, the at least one of the liquid nitrogen source or the liquid helium source are arranged to supply the at least one of the liquid nitrogen or the liquid helium to at least one of an underside of the substrate support or through channels in the substrate support.

[0016] An example method for etching a substrate in a substrate processing system includes controlling at least one radio frequency (RF) source to supply an RF signal to one or more coils to strike plasma in a processing chamber, wherein a substrate support is arranged in the processing chamber and the processing chamber is configured to support a substrate on an upper surface thereof, supplying liquid nitrogen from a liquid nitrogen source to the substrate support to control a temperature of the substrate support at or below a target cooling temperature value, to control an ion angular spread during etching of the substrate, and supplying liquid helium from a liquid helium source to the substrate support to control the temperature of the substrate support at or below the target cooling temperature value, to control the ion angular spread during etching of the substrate.

[0017] In some examples, supplying the liquid nitrogen to the substrate support and supplying the liquid helium to the substrate support occurs at a same time. In some examples, supplying the liquid nitrogen to the substrate support and supplying the liquid helium to the substrate support occurs in alternating time periods.

[0018] In some examples, the target cooling temperature value for the substrate support is less than or equal to negative twenty degrees Celsius. In some examples, the target cooling temperature value for the substrate support is less than or equal to negative sixty degrees Celsius.

[0019] In some examples, the method includes receiving a sensed temperature of the substrate support, supplying the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being greater than the target cooling temperature value, and stopping supply of the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being less than the target cooling temperature value.

[0020] In some examples, the method includes receiving an etching characteristic value indicative of an etching result condition of the substrate, and reducing the target cooling temperature value in response to the etching characteristic value failing to satisfy etching characteristic criteria. In some examples, the etching characteristic criteria includes at least one of an etching critical dimension of the substrate or a mask selectivity value of the substrate.

[0021] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: [0023] FIG. 1 is a functional block diagram of an example substrate processing system according to the present disclosure;

[0024] FIG. 2 is a diagram illustrating an ion incident angle relative to a plasma sheath above a surface of a substrate;

[0025] FIG. 3 is a functional block diagram of an example substrate processing system including a liquid nitrogen source and a liquid helium source;

[0026] FIG. 4 is a diagram illustrating example temperature distribution in the substrate processing chamber of FIG. 3;

[0027] FIGS. 5A and 5B are example plots of ion energy versus ion angular spread at different wafer temperatures;

[0028] FIG. 6A illustrates an example of a trench in a wafer prior to etching, and FIGS. 6B and 6C illustrate the example wafer after etching at different wafer temperatures, resulting in different critical dimensions;

[0029] FIG. 7A illustrates an example of a mask in a wafer prior to etching, and FIGS. 7B and 7C illustrate different etching mask selectivity at different wafer temperatures; and

[0030] FIG. 8 is a flowchart depicting an example process for cooling an electrostatic chuck using liquid nitrogen and liquid helium, in a substrate processing system.

[0031] In the drawings, reference numbers may be reused to identify similar and/or identical elements.

DETAILED DESCRIPTION

[0032] During substrate processing, a substrate is arranged on a pedestal such as an electrostatic chuck (ESC), process gases are supplied, and plasma is struck in the processing chamber. Exposed surfaces of components within the processing chamber experience wear due to exposure to the plasma.

[0033] High bias voltage/power with a low bias frequency may be used to etch very high aspect ratio trenches or holes. The high bias power generates high energy ions which may interact with sidewalls during etching to produce critical dimensions that have bowing characteristics. The high energy ions may degrade mask selectivity, Si/SiO2 or SiO2/Si selectivity, etc. [0034] In some examples, liquid N2 and/or liquid helium are used to cool an electrostatic chuck to below negative 20°C (or higher or lower temperatures). At the lower temperatures generated by the liquid nitrogen and/or liquid helium, radicals present in the plasma may be physiosorbed on sidewalls of trenches or holes during etching, to protect the sidewalls from bowing/etching.

[0035] A small layer of cold plasma may be produced on the wafer, and the cold plasma may slow down ion random motions (Ti) or ion temperature. Therefore, the cryogenic chuck may cool ions and reduce ion angular spread, which helps protect the sidewalls of the etching wells, and enhances the critical dimension (CD) characteristics due to improved ion directionality (e.g., compared to implementations where the chuck is at a higher temperature).

[0036] Cooling the wafer temperature with liquid N2 and/or liquid helium enhances physisorption of radicals in the trench/hole sidewalls during etching, which may preserve a desired critical dimension characteristic. For example, a cryogenically cooled chuck (e.g., down to negative 20°C or below), may produce a cooler plasma in a narrow region near the wafter (as illustrated in the example of FIG. 3). This cools down the ion temperature which may produce a tighter ion angle, optionally without the use of very high bias power.

[0037] In some examples, the cooler plasma may allow moderate ion energy to preserve a desired critical dimension characteristic of the etching, without affecting mask selectivity or material to material selectivity (such as silicon to silicon oxide selectivity). The cooler plasma may facilitate better ion directionality, as illustrated in the examples of FIGS. 5 and 6, which may allow the cooled ions to be used with less bias voltage/power. Examples of improved mask selectivity due to the cooler ions are illustrated in FIGS. 7A-7C.

[0038] Referring now to FIG. 1 , an example substrate processing system 100 is shown. For example only, the substrate processing system 100 may be used for performing etching using RF plasma and/or other suitable substrate processing. The substrate processing system 100 includes a coil driving circuit 104. In some examples, the coil driving circuit 104 includes an RF source 108, a pulsing circuit 112, and a tuning circuit 114. The pulsing circuit 112 controls a TCP envelope of the RF signal and varies a duty cycle of the TCP envelope (e.g., between 1% and 99%) during operation. As can be appreciated, the pulsing circuit 112 and the RF source 108 can be combined or separate.

[0039] The tuning circuit 114 may be directly connected to one or more inductive coils 116. The tuning circuit 114 tunes an output of the RF source 108 to a desired frequency and/or a desired phase, matches an impedance of the coils 116 and/or splits power between the coils 116. While examples including multiple coils are shown, a single coil including a single conductor or multiple conductors can be used.

[0040] A dielectric window 120 is arranged along one side of a processing chamber 122. The processing chamber 122 further comprises a substrate support 124 (or pedestal) to support a substrate 128. The substrate support 124 may include an electrostatic chuck (ESC), a mechanical chuck or other type of chuck. Process gas is supplied to the processing chamber 122 and plasma 132 is generated inside of the processing chamber 122. An RF bias drive circuit 136 may be used to supply an RF bias to the substrate support 124 during operation to control ion energy. The RF bias drive circuit 136 may include an RF source and an impedance matching circuit (not shown). While a specific substrate processing system 100 and processing chamber 122 are shown as an example, the principles of the present disclosure may be applied to other types of substrate processing systems and processing chambers, such as a substrate processing system that generates plasma in-situ, that implements remote plasma generation and delivery (e.g., using a plasma tube, a microwave tube), etc.

[0041] In some embodiments, a plenum 140 is arranged adjacent to (e.g., above, as shown) the dielectric window 120. A gas delivery system 144 may be used to deliver gas from a gas source 146 via a valve 148 to the plenum 140. The gas may include cooling gas (air) that is used to cool the coils 116 and the dielectric window 120.

[0042] A gas delivery system 156 may be used to supply a process gas mixture to the processing chamber 122. The gas delivery system 156 may include gas sources 158 (e.g., precursor, vapor, one or more other gases, inert gases), a gas metering system 160 such as valves and mass flow controllers, and a manifold 162. A gas injector (not shown) may be arranged at a center of the dielectric window 120 (or other location) and is used to inject gas mixtures from the gas delivery system 156 into the processing chamber 122.

[0043] A heater/cooler 164 may be used to heat/cool the substrate support 124 to a predetermined temperature. An exhaust system 166 includes a valve 168 and pump 170 to control pressure in the processing chamber 122 and/or to remove reactants from the processing chamber 122 by purging or evacuation.

[0044] A system controller 172 may be used to control the process. The system controller 172 monitors system parameters and controls delivery of the gas mixtures, striking, maintaining and extinguishing the plasma, removal of reactants, supply of cooling gas, etc.

[0045] The substrate support 124 may include an edge ring system including an edge ring 174. As shown, the edge ring 174 is arranged above a bottom ring 176. The edge ring 174 may be configured to protect the bottom ring 176 from exposure to the plasma processing environment as described below in more detail. For example, the edge ring 174 extends from an inner diameter of the bottom ring 176 past an outer diameter of the bottom ring 176. In an example embodiment, an outer diameter of the edge ring 174 extends to and interfaces with a chamber liner (not shown in FIG. 1 ).

[0046] In some example embodiments, the system controller 172 controls a robot 180 to deliver substrates and/or edge rings to the processing chamber. The system controller 172 also controls one or more actuators 182 that move lift pins (not shown in FIG. 1 ) to selectively raise and lower the edge ring 174 to facilitate transfer of the edge ring 174 to and from the substrate support 124. The system controller 172 may also receive outputs from one or more sensors 184, which may be used to sense a height of the edge rings, to sense a temperature in the processing chamber, to sense a degree of etching (e.g., a critical dimension of etching, etching mask selectivity, etc.). Nonlimiting examples of sensors include optical sensors, physical sensors, piezo sensors, ultrasonic sensors, temperature sensors, etc.

[0047] FIG. 2 shows an ion incident angle (p relative to a plane 200 extending perpendicular to a top surface 202 of a substrate 204 (e.g., a wafer). The substrate 204 is disposed on a substrate support 206 and may receive a bias voltage represented by a voltage source 208. Plasma 210 is generated above the substrate 204. An electron depleted area 212 exists between the plasma 210 and the substrate 204 and is referred to as a plasma sheath. The plasma sheath has a thickness s. Plasma density is proportional to an inverse of the square root of thickness s.

[0048] For vertical and untitled or directional etching of the substrate, ion flow should be in a direction parallel to the plane 200 and/or in a direction, which is perpendicular to the top surface 202, as shown by arrows 220. However, due to plasma non-uniformity that results in sheath non-uniformity and since ions strike perpendicular to sheath, such non-uniform sheath or density can result in ion tilt angle as high as a couple of degrees. This is shown by arrows 224 and can result in tilted etching of features (e.g., holes, trenches, etc.) at the acute angle rather than at 90° relative to the surface 202. Stringent requirements can include operating with an ion incidence or tilt angle (or tilt angle) of less than 0.02°.

[0049] The tilt angle of ions (which is a result of plasma density and sheath nonuniformity) is directly related to etch rate non-uniformity. An ion non-uniformity percentage may be estimated as a maximum ion flux minus a minimum ion flux divided by the maximum ion flux, as represented by equation 1 , where ionnonuni is the ion non- uniformity. The ion non-uniformity is proportional to the etch rate non-uniformity ERnonuni.

[0050] Various parameters may be adjusted in an effort to improve plasma uniformity and minimize ion tilt angle. As an example, a transformer coupled plasma (TCP) system may include inner and outer reactor coils disposed above a TCP window. The size of the reactor coils, locations of the reactor coils, and the amount of current passing through the reactor coils can be adjusted to improve etch rate and plasma uniformity. The size of a chamber in which the inner and outer reactor coils are located may be increased to allow for implementation of larger reactor coils and/or increased distances between the reactor coils. Another parameter that may be adjusted is a ratio of an amount of current supplied to the inner reactor coil divided by an amount of current supplied to the outer reactor coil. Adjustment of the above-stated parameters provides a limited amount of improvement in etch rate uniformity. For example, adjusting these parameters may improve plasma non-uniformity to be as low as 5-10%, which may not satisfy the requirement of producing a highly uniform plasma that can provide a tilt angle below 0.02 degrees.

[0051] With the size requirements of features of a substrate decreasing and resolution and aspect ratio requirements increasing, it is becoming more and more difficult to meet these requirements with existing processing systems. Some feature size requirements can be as small as 10 nanometers or even lower. [0052] The examples set forth herein include electrostatic chuck (ESC) temperature control systems with substrate supports (e.g., electrostatic chucks) which are cooled with liquid nitrogen and/or liquid helium, to reach cryogenic temperatures such as negative 20°C or below, negative 60°C or below, negative 160°C or below, negative 200°C or below, etc. The cooled chuck reduces wafer temperatures, which may generate a narrow region of cold plasma at a surface of the wafer, to improve and minimize ion angle tilt. In some embodiments, temperature of the chuck is reduced/controlled to decrease the ion tilt angle, whereas in other embodiments, the temperature of the chuck is reduced/controlled to maintain the ion tilt angle while reducing the supplied bias voltage/power.

[0053] FIG. 4 is a diagram illustrating example temperature distribution in the substrate processing chamber of FIG. 3. As shown in FIG. 4, the temperature near a dielectric window is about 50 to 600 degrees Kelvin. An example temperature at a wall of the processing chamber is about 333 degrees Kelvin.

[0054] As shown in FIG. 4, the electrostatic chuck and a wafer 422 on the chuck may be cooled to about 100 degrees K, via liquid nitrogen and/or liquid helium. This may produce a narrow region of cold plasma on a surface of the wafer of about two-hundred degrees Kelvin or below, reducing ion angle spread and improving etching characteristics as described above.

[0055] FIGS. 5A and 5B are example plots of energy versus angle of spread at different wafer temperatures. FIG. 5A illustrates an example ion energy versus ion angle spread at a higher chuck temperature, such as about 85 degrees Celsius, which results in an angle of spread of about 3.32 degrees.

[0056] FIG. 5B illustrates an example ion energy versus ion angle of spread at a lower chuck temperature (e.g., due to cooling from liquid nitrogen and/or liquid helium), such as about negative 20 degrees Celsius., which results in an angle of spread of about 2.2 degrees. Therefore, the reduced temperature chuck results in ions having a tighter spread and angle, for improved etching characteristics.

[0057] FIG. 6A illustrates an example of a trench in a wafer prior to etching, and FIGS. 6B and 6C illustrate the example wafer after etching at different wafer temperatures, resulting in different critical dimensions. For example, FIG. 6B illustrates an example etch well width at a higher chuck temperature, such as about 85 degrees Celsius, which results in an example etch well width which increases from 10 nm at the base of the mask to 22.2 nm (due to bowing from the high energy ions, etc.).

[0058] FIG. 6C illustrates an example etch well width at a lower chuck temperature, such as about negative twenty degrees Celsius, which results in an example etch well width of 20.1 nm. Therefore, the cooler chuck temperature facilitates a narrower critical dimension for etching the wafer.

[0059] FIG. 7A illustrates an example of a mask in a wafer prior to etching, and FIGS. 7B and 7C illustrate different etching mask selectivity at different wafer temperatures. For example, FIG. 7B illustrates an example mask reduction at a higher chuck temperature, such as about 85 degrees Celsius, which results in a mask reduction of about 154 nm (due to high energy ions hitting the mask layer, etc.).

[0060] FIG. 6C illustrates an example mask reduction at a lower chuck temperature, such as about negative twenty degrees Celsius, which results in a mask reduction of about 126 nm. Therefore, the cooler chuck temperature facilitates an improved mask selectivity.

[0061] FIG. 8 is a flowchart depicting an example process for cooling an electrostatic chuck using liquid nitrogen and liquid helium, in a substrate processing system. Portions of the process may be performed by, for example, the system controller 372 of FIG. 3. At 804, the process begins by placing a substrate on the electrostatic chuck (e.g., a wafer to be etched by the substrate processing system).

[0062] At 808, the system controller is configured to supply liquid nitrogen to cool the electrostatic chuck. For example, liquid nitrogen may be supplied from a liquid nitrogen source, such as the liquid nitrogen source 370 of FIG. 3 (e.g., by opening a valve in a flow path between the liquid nitrogen source and the electrostatic chuck). The liquid nitrogen may be supplied to an underside of the electrostatic chuck, through channels in the electrostatic chuck, etc.

[0063] At 812, the system controller is configured to supply liquid helium to cool the electrostatic chuck. For example, liquid helium may be supplied from a liquid nitrogen source, such as the liquid nitrogen source 364 of FIG. 3 (e.g., by opening a valve in a flow path between the liquid helium source and the electrostatic chuck). The liquid helium may be supplied to an underside of the electrostatic chuck, through channels in the electrostatic chuck, etc. Although FIG. 8 illustrates both liquid nitrogen and liquid helium being supplied to cool the electrostatic chuck, other example embodiments may include only one of liquid nitrogen and liquid helium, may use cooling gas or liquid other than nitrogen and helium, etc. The liquid nitrogen and liquid helium may be supplied to the chuck at the same time, or alternately.

[0064] The system controller is configured to receive a temperature of the electrostatic chuck at 816. For example, one or more temperature sensors may be used to sense a temperature of the electrostatic chuck as it is being cooled by the liquid helium and the liquid nitrogen.

[0065] At 820, control determines whether a target temperature has been reached. For example, a target temperature may be set to maintain the electrostatic chuck at a low temperature (e.g., cryo-temperature) sufficient to provide a desired angular ion spread during etching.

[0066] If the target temperature is not satisfied at 820, control returns to 808 to further supply liquid nitrogen to the electrostatic chuck, and further cool the electrostatic chuck. When the target temperature is satisfied at 820, control proceeds to 824 to etch the substate. For example, performing etching while the electrostatic chuck is at a target (e.g., cryogenic) temperature may reduce angular ion spread due to colder plasma ions, leading to improved etching with narrower critical dimensions and improved etching mask selectivity (e.g., as compared to etching performed at higher temperatures).

[0067] At 828, control determines a result condition after performing the etching operation. For example, control may determine whether angular ion spread met a specified threshold condition (e.g., etching characteristic criteria), whether a critical dimension of the etching meets a specified threshold condition, whether mask selectivity met a specified threshold condition, etc.

[0068] These parameters may be determined based on sensor readings configured to monitor a result condition of the etching, may be evaluated by a system operator viewing images of the etch result, etc. For example, the etching characteristic criteria may include an etching critical dimension of the substrate, a mask selectivity value of the substrate, etc.

[0069] At 832, control determines whether an etch condition is satisfied. For example, control may determine whether a desired critical dimension of the etching has been achieved. If so, the process ends. If the etch condition is not satisfied, control adjusts the target temperature at 836, and returns to 804 to further supply liquid nitrogen. In some examples, the target temperature may be adjusted in order to achieve a desired ion spread angle, a desired mask selectivity, etc.

[0070] The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

[0071] Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0072] In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.

[0073] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

[0074] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g., a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0075] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.

[0076] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.

Claims

CLAIMS What is claimed is:

1 . A substrate processing system comprising: a processing chamber including a window; a substrate support arranged in the processing chamber, configured to support a substrate on an upper surface thereof; at least one radio frequency (RF) source configured to supply an RF signal to one or more coils; at least one of a liquid nitrogen source or a liquid helium source arranged to supply at least one of liquid nitrogen or liquid helium to the substrate support; and a controller configured to strike plasma by supplying RF power from the at least one radio frequency (RF) source to the one or more coils, and to supply the at least one of liquid nitrogen or liquid helium to the substrate support to control a temperature of the substrate support at or below a target cooling temperature value to control an ion angular spread during etching of the substrate.

2. The substrate processing system of claim 1 , wherein: the at least one of the liquid nitrogen source or the liquid helium source includes the liquid nitrogen source; and the controller is configured to control the liquid nitrogen source to supply liquid nitrogen to the substrate support to control the temperature of the substrate support at or below the target cooling temperature value.

3. The substrate processing system of claim 1 , wherein: the at least one of the liquid nitrogen source or the liquid helium source includes the liquid helium source; and the controller is configured to control the liquid helium source to supply liquid helium to the substrate support to control the temperature of the substrate support at or below the target cooling temperature value.

4. The substrate processing system of claim 1 , wherein: the at least one of the liquid nitrogen source or the liquid helium source includes both the liquid nitrogen source and the liquid helium source; and the controller is configured to control the liquid nitrogen source to supply liquid nitrogen to the substrate support, and to control the liquid helium source to supply liquid helium to the substrate support, to control the temperature of the substrate support at or below the target cooling temperature value.

5. The substrate support of claim 4, wherein the controller is configured to supply the liquid nitrogen and the liquid helium to the substrate support at a same time.

6. The substrate support of claim 4, wherein the controller is configured to supply the liquid nitrogen and the liquid helium to the substrate support in alternating time periods.

7. The substrate processing system of claim 1 , wherein the target cooling temperature value for the substrate support is less than or equal to negative twenty degrees Celsius.

8. The substrate processing system of claim 7, wherein the target cooling temperature value for the substrate support is negative twenty degrees Celsius.

9. The substrate processing system of claim 7, wherein the target cooling temperature value for the substrate support is less than or equal to negative 60 degrees Celsius.

10. The substrate processing system of claim 9, wherein the target cooling temperature value for the substrate support is less than or equal to negative 160 degrees Celsius.

11. The substrate processing system of claim 10, wherein the target cooling temperature value for the substrate support is less than or equal to negative 200 degrees Celsius.

12. The substrate processing system of claim 1 , wherein the controller is configured to: receive a sensed temperature of the substrate support; supply the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being greater than the target cooling temperature value; and stop supplying the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being less than the target cooling temperature value.

13. The substrate processing system of claim 1 , wherein the controller is configured to: receive an etching characteristic value indicative of an etching result condition of the substrate; and reduce the target cooling temperature value in response to the etching characteristic value failing to satisfy etching characteristic criteria.

14. The substrate processing system of claim 13, wherein the etching characteristic criteria includes at least one of an etching critical dimension of the substrate or a mask selectivity value of the substrate.

15. The substrate processing system of claim 1 , wherein the at least one of the liquid nitrogen source or the liquid helium source are arranged to supply the at least one of the liquid nitrogen or the liquid helium to at least one of an underside of the substrate support or through channels in the substrate support.

16. A method for etching a substrate in a substrate processing system, the method comprising: controlling at least one radio frequency (RF) source to supply an RF signal to one or more coils to strike plasma in a processing chamber, wherein a substrate support is arranged in the processing chamber and the processing chamber is configured to support a substrate on an upper surface thereof; supplying liquid nitrogen from a liquid nitrogen source to the substrate support to control a temperature of the substrate support at or below a target cooling temperature value, to control an ion angular spread during etching of the substrate; and supplying liquid helium from a liquid helium source to the substrate support to control the temperature of the substrate support at or below the target cooling temperature value, to control the ion angular spread during etching of the substrate.

17. The method of claim 16, wherein supplying the liquid nitrogen to the substrate support and supplying the liquid helium to the substrate support occurs at a same time.

18. The method of claim 16, wherein supplying the liquid nitrogen to the substrate support and supplying the liquid helium to the substrate support occurs in alternating time periods.

19. The method of claim 16, wherein the target cooling temperature value for the substrate support is less than or equal to negative twenty degrees Celsius.

20. The method of claim 19, wherein the target cooling temperature value for the substrate support is less than or equal to negative sixty degrees Celsius.

21 . The method of claim 16, further comprising: receiving a sensed temperature of the substrate support; supplying the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being greater than the target cooling temperature value; and stopping supply of the at least one of liquid nitrogen or liquid helium to the substrate support in response to the sensed temperature being less than the target cooling temperature value.

22. The method of claim 16, further comprising: receiving an etching characteristic value indicative of an etching result condition of the substrate; and reducing the target cooling temperature value in response to the etching characteristic value failing to satisfy etching characteristic criteria.

23. The method of claim 22, wherein the etching characteristic criteria includes at least one of an etching critical dimension of the substrate or a mask selectivity value of the substrate.