TW201903887A - Organic membrane circulating plasma etching method using sulfur and/or carbon-based chemicals - Google Patents

Abstract

A method of etching is described. The method includes providing a substrate having a first material containing organic material and a second material that is different from the first material, forming a first chemical mixture by plasma-excitation of a first process gas containing an inert gas, and exposing the first material on the substrate to the first chemical mixture. Thereafter, the method includes forming a second chemical mixture by plasma-excitation of a second process gas containing S and O, and optionally a noble element, or containing C and O, and optionally a noble element, and exposing the first material on the substrate to the second plasma-excited process gas to selectively etch the first material relative to the second material.

Description

Cyclic plasma etching method for organic film using sulfur and / or carbon-based chemicals

The present invention relates to a method for etching, and more particularly, to precise etching techniques for etching thin films for electronic component applications. [Related applications]

This application claims the priority of the following co-pending provisional applications: U.S. provisional patent application numbered April 26, 2017, entitled "METHOD OF CYCLIC PLASMA ETCHING OF ORGANIC FILM USING SULFUR-BASED CHEMISTRY" No. 62 / 490,504, and U.S. Provisional Patent Application Serial No. 62 / 490,512, entitled `` METHOD OF CYCLIC PLASMA ETCHING OF ORGANIC FILM USING CARBON-BASED CHEMISTRY '', filed on April 26, 2017 The disclosure of this case is incorporated by reference.

The present invention relates to a method for manufacturing a semiconductor element such as a integrated circuit and a transistor and a transistor element for the integrated circuit. In the manufacture of semiconductor devices (especially at the micro-scale), many manufacturing processes are performed, such as film deposition, etching mask generation, patterning, material etching and removal, and doping processes to repeatedly perform the A desired semiconductor element is formed thereon. Historically, with the use of microfabrication, transistors have been generated in a plane with wiring / metallization formed above them, and are therefore characterized by two-dimensional (2D) circuits or 2D manufacturing. Efforts on scaling have greatly increased the number of transistors per unit area in 2D circuits. However, as scaling enters single-digit nanometer semiconductor device manufacturing nodes, the efforts on scaling have encountered greater challenges. Semiconductor element manufacturers have expressed expectations for three-dimensional (3D) semiconductor elements in which transistors are stacked on top of each other.

As component structures become denser and develop vertically, the need for precise material etching becomes more intense. The trade-offs between selectivity, profile, ARDE (aspect ratio-dependent etching), and uniformity in the plasma etching process become difficult to manage. The current methods of patterning and pattern transfer by balancing these trade-offs cannot be maintained for a long time. The root cause of these trade-offs is the inability to independently control ion energy, ion flux, and free radical flux. However, self-limiting processes such as atomic layer etching (ALE) provide a viable method to avoid these trade-offs by dividing the etching process into successive steps of surface modification and removal of modified surface areas, thereby allowing freedom Separation of base flux and the effects of ion flux and energy.

The technique herein relates to component manufacturing using precision etching techniques.

A method of etching is described. The method includes providing a substrate having a first material containing an organic material and a second material different from the first material, forming a first chemical mixture by exciting a first processing gas containing an inert gas with a plasma, and forming a first chemical mixture on the substrate. A first material is exposed to the first chemical mixture. After that, the method includes: forming a second chemical mixture by exciting a second processing gas containing S and O and optional rare gas or C and O and optional rare gas by a plasma; and The first material is exposed to a second processing gas excited by the plasma to selectively etch the first material relative to the second material. In one embodiment, the second processing gas may include COS. In another embodiment, the second processing gas may include CO, CO ₂ , or SO ₂ .

Of course, the order of discussion of the different steps as described herein has been presented for clarity. Generally, these steps can be performed in any suitable order. In addition, although the various features, technologies, configurations, etc. of this article can be discussed in different places in this disclosure, I want to make the concepts work independently or in combination with each other. Therefore, the present invention can be embodied and examined in many different ways.

Note that this summary section does not explicitly indicate all embodiments and / or added novel implementations of the disclosure or the claimed invention. Instead, this summary only provides a preliminary discussion of different embodiments, and novel correspondence points that are superior to conventional techniques. For additional details and / or possible views of the present invention and embodiments, the reader may refer to the implementation section discussed further below and the corresponding drawings of this disclosure.

The techniques herein relate to component manufacturing using precision etching techniques. Some examples show that in semiconductor manufacturing, the front-end process (FEOL, such as transistor manufacturing) to the back-end process (BEOL, such as interconnect manufacturing), where oxide and nitride films (usually essentially silicon-containing) Etching is required with high precision.

Many manufacturing sequences in semiconductor manufacturing require precise etching techniques for both 2D (two-dimensional) and 3D (three-dimensional) element structures. Nonetheless, a three-layer etch mask (for example, containing photoresist, anti-reflective coating (ARC), organic carbon film) is still the main force for patterning the mask into the underlying layers. Current challenges involve obtaining pattern transfer without loading artifacts, vertical sidewall profiles, and a square bottom with excellent selectivity to the ARC layer. Continuous plasma etching processes do not allow solutions to such challenges.

According to various embodiments, a precise cycle plasma etching technique using chemicals including sulfur-based chemicals and carbon-based chemicals is described for etching organic carbon films. For sulfur-based chemicals, gaseous chemicals contain S and O (for example: COS / O ₂ / Ar gas mixture, or SO ₂ / O ₂ / Ar gas mixture) for use as a layer of mask (including Silicon ARC layer) etch organic carbon film. For carbon-based chemicals, gaseous chemicals contain C and O (for example: CO / O ₂ / Ar gas mixture, or CO ₂ / O ₂ / Ar gas mixture) for use as a layer of mask (including Silicon ARC layer) etch organic carbon film.

1 and 2 illustrate a method of etching a thin film according to several embodiments. The method depicted as flowchart 200 includes: providing a substrate having a first material 100 containing an organic material and a second material 110 different from the first material 100; in step 210, a first process containing an inert gas is excited by a plasma. Gas to form a first chemical mixture; and in step 220, exposing the first material on the substrate to the first chemical mixture, the above combination is depicted as the process 102 in FIG. During the process 102, the exposed surface of the first material 100 is modified to a limited depth to form a modified sub-layer 112 in the first material 100 during exposure to the first chemical mixture. For example, the inventors speculate that carbon-carbon bonds may be broken during this phase of the etch cycle.

Thereafter, the method includes forming a second chemical mixture by exciting a second processing gas containing S and O and optional rare elements with a plasma in step 230, and in step 240, changing the first material on the substrate 100 is exposed to the second plasma to stimulate the processing gas to selectively etch the first material 100 relative to the second material. The above combination is depicted as the process 104 in FIG. 1. During the process 104, the modified sub-layer 112 in the first material is removed or etched during the exposure to the second chemical mixture. Moreover, during the process 104, a protective layer 114 is formed on the second material 110 during exposure to the second chemical mixture. For example, the inventors speculated that the O * radical from the solution using _2, and the solution ₂ O COS or SO gas obtained via removal by adsorption during the phase-modified carbon layer. S * C atom with the free radical complexes formed on the sidewall surface of the second material 110, and providing a protective layer containing C _x S _y during the desorption stage to avoid sidewall consumption. In addition, a protective layer containing C _x S _y provides extremely high selectivity for ARC mask protection. Alternatively, the method includes: forming a second chemical mixture by exciting a second processing gas containing C and O and optional rare elements with a plasma in step 230, and in step 240, changing the first material on the substrate 100 is exposed to the second plasma to stimulate the processing gas to selectively etch the first material 100 relative to the second material. The above combination is depicted as the process 104 in FIG. 1.

Still further, the method may include forming a first chemical mixture by exciting a first processing gas containing an inert gas with a plasma, and exposing a first material on the substrate to the first chemical mixture. The above combination is depicted in FIG. 1的 工艺 106。 The process 106. During the process 106, the exposed surface of the first material 100 is modified to a limited depth to form another modified sub-layer 116 in the first material 100 during exposure to the first chemical mixture.

The first material 100 to be etched includes an organic material, consists essentially of an organic material, or consists of an organic material. The organic material may include a hard mask, a soft mask, or a planarization layer. The first material may include a carbon-containing mask, such as amorphous carbon. The first material may be deposited using a vapor deposition process or a spin-on deposition process.

The second material 110 may include a single layer or a multilayer stack. The second material 110 may be patterned as shown in FIG. 1. The second material may include an inorganic material. The second material may include Si, Ge, or metal (M), and optionally one or more elements selected from the group consisting of O, N, C, F, Cl, Br, and S. The second material may include silicon, silicon oxide, silicon nitride, silicon carbide, metal, metal oxide, metal nitride, metal carbide, or metal alloy, or a combination thereof. The second material may include a Si-containing anti-reflective coating (ARC) and a silicon oxide (for example, the Si content may be less than 20%, or more than 40%). The second material may be deposited using a vapor deposition process or a spin-on deposition process.

As described above, the first chemical mixture is formed by exciting the first processing gas from the plasma. The first processing gas contains an inert gas, such as a noble gas. In one embodiment, the first processing gas includes Ar. In another embodiment, the first processing gas consists essentially of Ar or consists of Ar.

As also mentioned above, the second chemical mixture is formed by exciting the second processing gas from the plasma. The second processing gas may include sulfur (S) and oxygen (O), and optionally a rare element such as Ar (argon). The second processing gas may include additives such as CO, CO ₂ , O ₂ , H ₂ , N ₂ , C _x H _y , C _x R _z , or C _x H _y R _z (where x, y, and z are greater than An integer of 0, and R is a halogen element). The second processing gas may include a compound having S and O, such as COS, SO ₂ , or SO ₃ . In one embodiment, the second processing gas includes SO ₂ , O ₂ , and Ar. In another embodiment, the second processing gas consists essentially of SO ₂ , O ₂ , and Ar or consists of SO ₂ , O ₂ , and Ar. Alternatively, in another embodiment, the second processing gas includes COS, O ₂ , and Ar. In yet another embodiment, the second processing gas consists essentially of COS, O ₂ and Ar or consists of COS, O ₂ and Ar.

Alternatively, the second processing gas may contain carbon (C) and oxygen (O), and optionally contains a rare element such as Ar (argon). The second processing gas may include a compound having both C and O, such as CO or CO ₂ . The second processing gas may include additives such as COS, SO ₂ , O ₂ , H ₂ , N ₂ , C _x H _y , C _x R _z , or C _x H _y R _z (where x, y, and z are greater than An integer of 0, and R is a halogen element). For example, the second processing gas may include CO, or CO ₂ , or both CO and CO ₂ . In one embodiment, the second processing gas includes CO ₂ , O ₂ , and Ar. In another embodiment, the second processing gas consists essentially of CO ₂ , O ₂ , and Ar or consists of CO ₂ , O ₂ , and Ar. Alternatively, in another embodiment, the second processing gas includes CO, O ₂ , and Ar. In yet another embodiment, the second processing gas consists essentially of CO, O ₂ and Ar or consists of CO, O ₂ and Ar.

The plasma excitation of the first processing gas and / or the second processing gas may be in situ (ie, the first and / or second chemical mixture is formed in a gas phase, a vacuum environment adjacent to the substrate), or offsite (ie, The first and / or second chemical mixture is formed in a vacuum environment in a gas phase remotely disposed relative to the substrate). 3A to 3D provide several plasma generation systems that can be used to facilitate plasma excitation of a process gas. FIG. 3A depicts a capacitive coupling plasma (CCP) system, in which a plasma is formed near a substrate between an upper plate electrode (UEL) and a lower plate electrode (LEL), and the lower electrode also serves as an electrostatic chuck (ESC) to support and Fix the substrate. Plasma is formed by coupling radio frequency (RF) power to at least one of the electrodes. As shown in FIG. 3A, the RF power is coupled to both the upper and lower electrodes, and the power coupling may include different RF frequencies. Alternatively, multiple RF power sources may be coupled to the same electrode. In addition, direct current (DC) power can be coupled to the upper electrode.

FIG. 3B depicts an inductively coupled plasma (ICP) system in which a plasma is formed near a substrate between an inductive element (such as a planar or solenoid / spiral coil) and a lower plate electrode (LEL), which As an electrostatic chuck (ESC) to support and fix the substrate. Plasma is formed by coupling radio frequency (RF) power to an inductive coupling element. As shown in FIG. 3B, the RF power is coupled to both the inductive element and the lower electrode, and the power coupling may include different RF frequencies.

FIG. 3C depicts a surface wave plasma (SWP) system in which a plasma is formed near a substrate between a slotted plane antenna and a lower plate electrode (LEL), which also serves as an electrostatic chuck (ESC) To support and fix the substrate. Plasma is formed by coupling radio frequency (RF) power at the microwave frequency to a slot-shaped planar antenna via a waveguide and a coaxial line. As shown in FIG. 3C, the RF power is coupled to both the slot-shaped planar antenna and the lower electrode, and the power coupling may include different RF frequencies.

3D depicts a remote plasma system in which a plasma is formed in an area remote from the substrate and separated from the substrate by a filter configured to prevent the transfer of charged particles from a remote plasma source to a processing area near the substrate. The substrate is supported by a lower plate electrode (LEL), which also serves as an electrostatic chuck (ESC) to accommodate the substrate. Plasma is formed by coupling radio frequency (RF) power to a plasma generating device located adjacent to a distant area. As shown in FIG. 3D, the RF power is coupled to both the plasma generating device and the lower electrode adjacent to the remote area, and the power coupling may include different RF frequencies.

The plasma processing systems of FIGS. 3A to 3D are intended to depict a number of techniques for implementing the described stepwise ion / radical process. Other embodiments are envisaged to include both combinations and variations of the systems described.

The gas pressure used in the exposure step when a first chemical mixture is formed by exciting a first processing gas containing an inert gas such as a rare gas, and the first material on the substrate is exposed to the first chemical mixture. Can be less than or equal to 1000 mTorr. For example, the gas pressure can range from 10 mTorr to 100 mTorr. In addition, the substrate can be electrically biased by coupling RF power to the lower plate electrode (LEL). RF power may not be applied to the plasma generator.

A second chemical mixture is formed by exciting a second processing gas containing S and O (such as COS or SO ₂ ), O ₂ , and optionally a rare gas, and the second material on the substrate is exposed to the first In the case of two chemical mixtures, the pressure of the gas used in the exposure step may be less than or equal to 1000 mTorr. For example, the gas pressure can range from 10 mTorr to 100 mTorr. In addition, the substrate can be electrically biased by coupling RF power to the lower plate electrode (LEL). RF power may not be applied to the plasma generator.

When the first chemical mixture containing a rare gas (such as Ar) is excited by the plasma to form a first chemical mixture, and the first material on the substrate is exposed to the first chemical mixture, and when the When the second chemical mixture of S and O (such as COS or SO ₂ ) is used to form a second chemical mixture, the inventors have observed that cyclic plasma etching results in (i) almost no lateral etching and (ii) almost no mask bottom Cut, and (iii) Almost no aspect ratio dependent etching (ARDE).

Within the scope of the patent application below, the limitations of any subsidiary item may be attached to any independent claim item.

Specific details have been explained in the previous description, such as a description of the special geometry of the processing system and the many components and processes used in it. It should be understood, however, that the techniques herein may be practiced in other embodiments that depart from these specific details, and such details are for the purpose of explanation and not limitation. The embodiments disclosed herein have been described with reference to the accompanying drawings. Likewise, for the purpose of explanation, specific numbers, materials, and configurations have been described to provide a complete understanding. Despite this, the embodiments can be implemented without such specific details. Elements having substantially the same functional structure are denoted by similar reference symbols, and therefore any redundant description may be omitted.

To facilitate an understanding of the various embodiments, the techniques are described in multiple discrete operations. The described order should not be interpreted as implying that the operations must be order dependent. In particular, these operations need not be performed in the order recited. The operations described may be performed in a different order than the embodiment. In additional embodiments, many additional operations may be performed and / or the operations described may be omitted.

A "substrate" or "target substrate" as used herein refers broadly to an object processed in accordance with the present invention. The substrate may include any material portion or structure of an element (especially a semiconductor or other electronic component), and may be, for example, a base substrate structure such as a semiconductor wafer, a reduction mask, or a base substrate structure on or over One layer (such as a film). Therefore, the substrate is not limited to any particular base structure, underlying or overlying layer, patterned or unpatterned, but is envisaged to include any such layer or base structure, and any combination of layers and / or base structures. This description may refer to a specific type of substrate, but this is for illustrative purposes only.

Those skilled in the art will also understand that many changes can be made to the operation of the techniques described above and still achieve the same objectives of the present invention. Such changes are intended to be encompassed by the scope of this disclosure. Therefore, the previous description of the embodiments of the present invention is not intended to be limiting. More precisely, any limitations of the embodiments of the invention are presented in the scope of the following patent applications.

100‧‧‧ first material

102‧‧‧Process

104‧‧‧Process

106‧‧‧Process

110‧‧‧Second Material

112‧‧‧ Sublayer

114‧‧‧ protective layer

116‧‧‧Sublayer

200‧‧‧flow chart

210‧‧‧ steps

220‧‧‧step

230‧‧‧ steps

240‧‧‧ steps

In the accompanying drawings:

FIG. 1 depicts a schematic diagram of a method for etching a thin film on a substrate according to an embodiment; FIG.

FIG. 2 provides a flowchart illustrating a method of etching a substrate according to an embodiment; and

3A to 3D provide schematic views of a plasma processing system for a method for performing etching according to various embodiments.

Claims (20)

An etching method includes: providing a substrate having a first material and a second material different from the first material, the first material including an organic material; and forming a first processing gas including an inert gas by plasma activation A first chemical mixture; exposing the first material on the substrate to the first chemical mixture; and then stimulating by plasma to contain O and a group selected from the group consisting of S and C and a rare element Forming a second chemical mixture with a second processing gas of at least one element; and exposing the first material on the substrate to the second processing gas excited by a plasma to selectively etch the second material relative to the second material The first material. For example, the etching method according to item 1 of the patent application scope, wherein the first processing gas contains a rare element. For example, the etching method according to item 1 of the patent application scope, wherein the first processing gas includes Ar. For example, the etching method according to item 1 of the patent application scope, wherein the first processing gas is composed of Ar. For example, the etching method of claim 1 in the patent application scope, wherein the second processing gas includes a compound having both S and O, or a compound having both C and O. For example, the etching method according to item 1 of the patent application scope, wherein the second processing gas includes CO, CO ₂ , COS, or SO ₂ . For example, the etching method according to item 1 of the patent application scope, wherein the second processing gas is composed of O ₂ , Ar, and a gas selected from the group consisting of CO ₂ , CO, SO ₂ , and COS. For example, the etching method of item 1 of the patent application scope, wherein the second processing gas further comprises O ₂ , H ₂ , N ₂ , C _x H _y , C _x R _z , or C _x H _y R _z , and wherein x, y and z are integers greater than 0, and R is a halogen element. For example, the etching method according to item 1 of the patent application scope, wherein the first material comprises amorphous carbon or a hard mask containing carbon. For example, the etching method of item 1 of the patent application scope, wherein the second material comprises an inorganic material. For example, the etching method of item 1 of the patent application scope, wherein the second material includes Si, Ge, or metal (M), and optionally selected from the group consisting of O, N, C, F, Cl, Br, and S One or more elements of a group. For example, the etching method of item 1 of the patent application scope, wherein the second material comprises silicon, silicon oxide, silicon nitride, silicon carbide, metal, metal oxide, metal nitride, metal carbide, or metal alloy, Or a combination. For example, the etching method of item 1 of the patent application scope, wherein the second material includes an anti-reflective coating (ARC) containing Si and silicon oxide. For example, the etching method according to the scope of patent application of claim 1 further includes: modifying the exposed surface of the first material to a limited depth to form a modified material in the first material during the exposure to the first chemical mixture. And a modified sub-layer in the first material during exposure to the second chemical mixture. The etching method according to item 14 of the patent application scope further comprises: forming a protective layer on the second material during exposure to the second chemical mixture. For example, the etching method according to the patent application No. 15 further includes: removing the protective layer on the second material during the exposure to the first chemical mixture. For example, the etching method of item 1 of the patent application range, wherein the step of exciting the first processing gas or the second processing gas by the plasma includes using a capacitive coupling including an upper plate electrode and a lower plate electrode supporting the substrate The plasma source generates a plasma. For example, the etching method of claim 1 in the patent scope, wherein the step of exciting the first processing gas or the second processing gas by the plasma includes using an inductive coupling circuit including an inductive element and a lower plate electrode supporting the substrate. The plasma source generates a plasma. For example, the etching method of claim 1, wherein the step of exciting the first processing gas or the second processing gas by the plasma includes generating a plasma using a remote plasma source. For example, the etching method according to the scope of application for patent further includes: repeatedly forming the first chemical mixture, exposing the first material to the first chemical mixture, forming the second chemical mixture, and exposing the first material to A step of the second chemical mixture to gradually remove additional portions of the first material.