Selective etching of a substrate

Abstract

A method for selectively cleaning and / or etching a sample is described herein. The method includes selectively forming a film in a trench of a substrate such that the trench can be selectively etched. A polymer film is deposited on a bottom surface of the trench without being deposited on sidewalls. A second film is selectively formed in the trench without forming the second film on the polymer film. The polymer is then removed from the bottom surface of the trench and etching is then performed on the bottom surface of the trench using etching chemistry, wherein the second film protects the sidewalls from being etched.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure are generally directed to a method for etching a substrate, where such method for etching uses a flowable polymer film to achieve improved etch selectivity between different regions of the substrate. BACKGROUND

[0002] In the semiconductor industry, devices are fabricated through many fabrication processes that produce structures of ever decreasing dimensions. As device geometries shrink, controlling process uniformity and reproducibility of devices becomes more challenging, particularly in upstream processes.

[0003] Integrated circuits are implemented through a variety of processes that produce intricately patterned layers of materials on a substrate surface. Producing patterned materials on a substrate uses controlled methods of forming and removing exposed materials. For example, in a gap fill operation, a material can be formed or deposited to fill a trench or other feature formed on a semiconductor substrate. These fill operations can be challenging due to the trench or feature can be characterized by a high aspect ratio and reduced critical dimensions. For example, because deposition can occur at the top of the trench or feature as well as along the sidewalls of the trench or feature, continuous deposition can pinch off the trench or feature (including between sidewalls within the trench) and can create voids. This can then impact device performance as well as subsequent processing operations.

[0004] In current etch processes, a substrate can be made of silicon and silicon nitride. When the substrate is exposed to air, the substrate can have a bottom comprising silicon oxide (SiO) and sidewalls comprising silicon oxynitride (SiON). As devices continue to shrink, target etch parameters are also reduced. To address this issue, a selective etch or selective chemical passivation is preferred. Because the bottom and sidewalls contain similar materials (SiO and SiON), a selective etch or selective chemical passivation is difficult to apply. Therefore, there is a need to improve selective etching of the substrate to enable smaller target etch parameters. SUMMARY

[0005] In some embodiments of the disclosure, a method of cleaning and etching a sample is provided. The method can include placing a substrate into a chamber, where the substrate can include a layer including at least one trench formed in the layer. The at least one trench of the method can have a top surface, a bottom surface, and at least one sidewall. In some embodiments, the method can include depositing a polymer film on the bottom surface of the at least one trench without depositing the polymer film on the at least one sidewall of the at least one trench. In some embodiments, the method can include selectively forming a second film on the layer without forming the second film on the polymer film. In some embodiments, the method can include removing the polymer film from the bottom surface of the at least one trench. In some embodiments, the method can further include etching the bottom surface of the trench using an etch chemistry, where the second film protects the at least one sidewall from the etch chemistry.

[0006] In another embodiment of the disclosure, a method of cleaning and etching a substrate is provided. The method can include placing a substrate into a chamber, where the substrate includes a layer having at least one trench formed in the layer, the at least one trench having a top surface, a bottom surface, and at least one sidewall. The method further includes depositing a polymer film on the bottom surface of the at least one trench without depositing the polymer film on the at least one sidewall of the at least one trench, and selectively forming a second film on the layer without forming the second film on the polymer film. The method further includes removing the polymer film from the bottom surface of the at least one trench, performing an etch process, where the etch process includes applying ammonium fluoride to the substrate. The etch process of the method can selectively interact with the bottom surface of the at least one trench and not interact with the top surface and the at least one sidewall. BRIEF DESCRIPTION OF DRAWINGS

[0007] The disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that different "instances" of "an" or "one" implementation in this disclosure do not necessarily all refer to the same implementation, and such references mean at least one.

[0008] Figure 1 A cross-sectional view of a processing chamber of one embodiment is depicted.

[0009] Figure 2A A cross-sectional view of a multilayer of a sample of one embodiment is depicted;

[0010] Figure 2B A cross-sectional view of a multilayer of a sample of one embodiment is depicted, where the sample has been etched to have a U-shaped profile;

[0011] Figure 3Depiction of deposition processes according to various molecular layer deposition techniques;

[0012] Figure 4 is a flowchart representing a method for selectively cleaning a substrate according to embodiments of the present disclosure; and

[0013] Figure 5 Illustration of a trench of a substrate selectively cleaned according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0014] Polymeric films can be used in the manufacture of semiconductor device elements for a variety of structures and processes, including applications as mask materials, etch resist materials, and trench fill materials, among others. More particular examples of applications of polymeric thin films include formation of thermal implant hard masks, metal gate (MG) cut hard masks, MG fabrication, and reverse tone patterning, among others. The present disclosure includes forming polymeric films on semiconductor substrates using molecular layer deposition (MLD).

[0015] Embodiments disclosed herein describe a method for selectively cleaning and / or selectively etching a substrate. The method for cleaning / etching a substrate can include placing a substrate into a chamber, where the substrate can include a layer including at least one trench formed in the layer, the at least one trench having a top surface, a bottom surface, and at least one sidewall. The method for etching can include depositing a polymeric film on the bottom surface of the at least one trench without depositing the polymeric film on the at least one sidewall of the at least one trench. The method can further include selectively forming a barrier film on the layer without forming the barrier film on the polymeric film. For example, the barrier film can be formed using a self-assembled monolayer (SAM) deposition technique. The method can further include removing the polymeric film from the bottom surface of the at least one trench and etching the bottom surface of the trench using an etching chemistry, where the barrier film protects the at least one sidewall from the etching chemistry.

[0016] By selectively coating one or more portions of the substrate with different films, the profile of the substrate can be improved and the blowout of the critical dimensions of the trench can be improved. It has been found that using a self-assembled monolayer (SAM) blocks and / or protects surfaces from being etched. By selectively protecting surfaces from being etched, this allows for the removal of material in selective areas of the trench (e.g., such as any oxidized surfaces) while avoiding the blowout of critical dimensions (e.g., such as the trench width or profile). The inventors have found that the bottom surface of the trench in the substrate is often oxidized, which is generally detrimental to the performance of the final product. To remove the oxidized surfaces, an etch process step can be performed. However, at this stage, not every surface needs to be etched as this can affect the profile of the substrate (e.g., the profile of the trench formed in or on the substrate).

[0017] Accordingly, a SAM can be formed on the top surface, the side surface, or a combination of the above surfaces to protect these surfaces from being etched. The inventors have found that depositing a polymer film on the bottom surface of the trench prevents the SAM from being formed on the bottom surface, such that the SAM is formed on the top surface, the sidewall surface, or a combination of the above surfaces. In various embodiments, a SAM consists of an ordered arrangement of spontaneously assembled organic molecules adsorbed on a surface. These molecules generally include one or more parts (head groups) that have an affinity for the substrate and a relatively long, inert, linear part.

[0018] In various embodiments, a flowable polymer is deposited on the substrate, where the flowable polymer does not attach to the sidewalls of the trench, but rather collects at the bottom of the trench. The flowable polymer can set or harden at the bottom of the trench surface without forming on the sidewalls of the trench. Subsequently, a SAM can not attach to the polymer that has been selectively deposited at the bottom of the trench. Accordingly, after selectively forming the SAM (e.g., everywhere except the polymer at the bottom of the trench), the polymer film at the bottom of the trench can be removed. Thereafter, an etch chemistry can selectively etch the oxide on the bottom surface of the trench and / or etch the bottom surface of the trench at a much higher rate than the SAM etches the SAM. Accordingly, the SAM protects the sidewalls and / or top of the trench from being etched and the etching can be selectively performed on the bottom surface of the trench.

[0019] By selectively etching or cleaning certain surfaces of the trench of the substrate without etching other surfaces of the trench, a lower degree of variation in the trench width across the trench depth is found in the etched sample (i.e., the substrate) compared to a conventional plasma etch process. Accordingly, the inventors have found a method of selectively cleaning or etching the bottom surface of the trench without etching or nearly etching the top and / or sidewalls of the trench.

[0020] In several embodiments, because SAM and the polymer film have different chemical reactivity, SAM can be selectively formed on a surface other than the polymer film. Therefore, according to several aspects of this disclosure, SAM can react with surfaces on which there is no polymer film.

[0021] This document discloses an embodiment of a method for selectively cleaning or etching a substrate, the method comprising depositing a polymer film and selectively forming a second film on the substrate. The polymer film is then removed and the substrate is etched until a target amount of substrate has been etched. The polymer film may be deposited on the bottom surface of at least one trench of the substrate such that when the second film is formed on the substrate, the second film will not form on the bottom surface due to the polymer film. It has been found that the polymer film and the second film may have different chemical reactivity to control the selectivity of deposition and / or formation of films thereon.

[0022] As used herein, the term "substrate" refers to a surface or part thereof on which processing is performed. Those skilled in the art will also understand that reference to "substrate" may refer only to a portion of a substrate, unless the context clearly indicates otherwise. Furthermore, the reference to "deposit on a substrate" can refer to a bare substrate and a substrate on which one or more films or features are deposited or formed.

[0023] As used herein, "substrate" can also refer to any substrate on which a film treatment is performed during manufacturing processes, or to a material surface formed on a substrate. For example, depending on the application, substrate surfaces on which treatments can be performed include materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, silicon nitride, doped silicon, silicon germanium, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials. Substrates include, but are not limited to, semiconductor wafers.

[0024] The substrate can be exposed to pretreatment processes to grind, etch, reduce, oxidize, hydroxylate (or otherwise generate or graft target chemical moiety to impart chemical functionality), anneal, and / or bake the substrate surface. In addition to film treatments performed directly on the surface of the substrate itself, any film treatment steps disclosed in this disclosure can also be performed on an underlayer formed on the substrate, as disclosed in more detail below, and the term "substrate surface" is intended to include such an underlayer as referred to in the context. Thus, for example, when a film / layer or a portion of a film / layer has already been deposited onto the substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface. What is included in a given substrate surface depends on the type of film to be deposited and the specific chemistry used. In one or more embodiments, the first substrate surface may include metal, metal oxide, or H-terminated Si. x Ge1-x The surface of the second substrate may include a Si-containing dielectric, or vice versa. In some embodiments, the substrate surface may contain certain functionalities (e.g., -OH, -NH, etc.).

[0025] Now refer to the attached diagram, Figure 1 This is a cross-sectional view of a processing chamber 100 (e.g., a semiconductor processing chamber) having one or more chamber components according to embodiments of the present disclosure. The processing chamber 100 can be used for processing in which a corrosive plasma environment and / or corrosive chemicals are provided. For example, the processing chamber 100 can be a chamber for a plasma etching reactor (also known as a plasma etcher). Examples of chamber components that can be exposed to plasma in the processing chamber 100 are a substrate support assembly 148, an electrostatic chuck (ESC), annular elements (e.g., a processing kit ring or a single annular element), chamber walls, a base, a nozzle 130, a gas distribution plate, a liner, a liner kit, a shield, a plasma baffle, a flow equalizer, a cooling base, a chamber window, a chamber cover, a nozzle, a processing kit ring, etc. In several embodiments, the processing chamber 100 is used to perform etching processes on a patterned substrate, the patterned substrate including a plurality of trenches formed on the substrate.

[0026] In one embodiment, the processing chamber 100 includes a chamber body 102 surrounding an internal space 106 and a nozzle 130. The nozzle 130 may (or may not) include a gas distribution plate. For example, the nozzle may be a multi-piece nozzle comprising a nozzle base and a nozzle gas distribution plate bonded to the nozzle base. Alternatively, in some embodiments, the nozzle 130 may be replaced by a cap and nozzle, or in other embodiments by multiple disc-shaped nozzle compartments with a plasma generation unit. The chamber body 102 may be made of aluminum, stainless steel, or other suitable materials. The chamber body 102 typically includes sidewalls 108 and a bottom 110. Any of the nozzle 130 (or cap and / or nozzle), sidewalls 108, and / or bottom 110 may include a multilayer anti-plasma coating.

[0027] The outer liner 116 may be disposed adjacent to the sidewall 108 to protect the chamber body 102. The outer liner 116 may be made of a halogen-resistant material, such as Al2O3 or Y2O3. In some embodiments, the outer liner 116 may be coated with a multilayer anti-plasma ceramic coating.

[0028] An exhaust port 126 may be defined within the chamber body 102 and may couple the internal space 106 to a pump system 128. The pump system 128 may include one or more pumps and throttle valves for venting and regulating the pressure of the internal space 106 of the processing chamber 100.

[0029] The nozzle 130 can be supported on the sidewall 108 of the chamber body 102 and / or the top portion of the chamber body. The nozzle 130 (or cover) can be opened to allow access to the interior space 106 of the processing chamber 100 and can provide a seal for the processing chamber 100 when closed. A gas control panel 158 can be coupled to the processing chamber 100 to supply processing gas and / or carrier gas to the interior space 106 through the nozzle 130 or cover and nozzle. Examples of processing gases that can be supplied by the gas control panel 158 and used for processing substrates / samples in the processing chamber 100 include silicon-containing gases, halogen-containing gases such as C2F6, SF6, HBr, NF3, CF4, CHF3, CH2F3, F, NF3, Cl2, CCl4, BCl3, and SiF4, and other gases such as O2 or N2O. Examples of carrier gases (also referred to herein as diluents) include N2, He, Ar, and other gases that are inert to the process gas (e.g., non-reactive gases). Nozzle 130 includes a plurality of gas delivery orifices 132 throughout the nozzle 130. Nozzle 130 may be or may include aluminum, anodized aluminum, an aluminum alloy (e.g., Al 6061), or anodized aluminum alloy. In some embodiments, the nozzle includes a gas distribution plate (GDP) bonded to the nozzle. GDP may be, for example, Si or SiC. GDP may additionally include a plurality of orifices aligned with the orifices in the nozzle.

[0030] A substrate support assembly 148 is disposed within the internal space 106 of the processing chamber 100, located below the nozzle 130. The substrate support assembly 148 holds a substrate 144 (e.g., a wafer) during processing. The substrate support assembly 148 may include an electrostatic chuck for securing the substrate 144 during processing, a metal cooling plate bonded to an electrostatic chuck, and / or one or more additional components. A liner may cover the periphery of the substrate support assembly 148. The liner may be a halogen-resistant material, such as Al₂O₃ or Y₂O₃. In some embodiments, the substrate support assembly, multiple portions of the substrate support assembly, and / or the liner may be coated with a metal layer and a barrier layer.

[0031] Processing chamber 100 may be an etching chamber. In various embodiments, an etching process is performed to selectively etch a film disposed on the surface of substrate 144. For example, substrate 144 may be a semiconductor wafer, a glass plate, a SiGe wafer, or another type of substrate. In one embodiment, the film disposed on substrate 144 includes a polymer film and a self-assembled monolayer. Substrate 144 may further comprise silicon (Si).

[0032] Figure 2AShowing a cross-sectional view of article 200 including substrate 206. In some embodiments, article 200 may have a layer stack (e.g., alternating layers of two or more materials). The layer stack may include a stack of silicon (Si) layers, silicon germanium (SiGe) layers, silicon nitride (SiN) layers, silicon dioxide (SiO2) layers, etc. In many embodiments, the stack includes a stack of alternating layers of two or more of the above materials (e.g., alternating stacks of Si and SiGe, alternating stacks of Si and SiO2, etc.). In one embodiment, article 200 corresponds to Figure 1 The substrate 144. The substrate 206 includes Si layers 260a-260f disposed on the substrate in a stacked manner 290. In some embodiments, the Si layers 260a-260f may be in the form of nanosheets (e.g., layers with nanometer-scale thickness). In one embodiment, all Si layers 260a-260f have approximately the same thickness. Alternatively, different Si layers 260a-260f may have different thicknesses.

[0033] A pattern mask 280 (also called an etch mask) may cover the top layer 260a in the stack 290. The pattern mask 280 may be a soft mask or a hard mask. Some hard masks that can be used include polysilicon hard masks and metal hard masks, such as tungsten hard masks or titanium nitride hard masks. The pattern mask 280 includes opening regions 270 that expose the underlying layers to etching chemicals during the etching process. The pattern mask 280 additionally includes a cover region that protects the underlying layers from the etching chemicals. Areas of the stack 290 located below the opening regions 270 that are not protected by the pattern mask 280 may undergo etching.

[0034] The article 200 can be etched through the pattern mask 280 to create cavities or trenches having approximately the same shape as the openings in the pattern mask 280. The etchant also typically etches the pattern mask 280 at a certain etch rate.

[0035] Figure 2BThe diagram shows a cross-sectional view of an article 204 including a substrate 206 having an etched layer stack 260a-260f. The etched treatment can be any etched treatment used in the art, including chemical etching. Chemical etching can include forming an ammonium fluoride salt using ammonia and hydrofluoric acid. Other chemical etchings may include, but are not limited to, using ammonia and water, NHF, NH4F, hydrogen fluoride, or hydrogen chloride. This treatment has etched cavities 400 (e.g., trenches) in layers 260a-260f. In one embodiment, the cavity 400 has a tapered cross-sectional shape, wherein the bottom of the cavity is slightly narrower than the top of the cavity, having a U-shaped profile. Notably, unlike the sidewalls produced by prior art etching treatments, the sidewalls of the trenches or holes formed by the etching treatment presented in this embodiment are almost vertical.

[0036] In several embodiments, native oxide can be formed on the bottom of the trench. To remove the native oxide, one or more etching or cleaning processes can be performed. However, these etching or cleaning processes may also etch the sidewalls of the trench, which may alter the trench profile. Alternatively, after the trench is formed, further processing may be performed to etch the substrate 206 that may be exposed at the bottom of the trench. However, etching the trench bottom (e.g., substrate 206) may also cause etching of the trench sidewalls, thereby again altering the profile of the trench walls. This can affect the critical dimensions of the manufactured device. The embodiments described herein allow the trench bottom to be cleaned or etched without negatively affecting the profile or critical dimensions of the device (e.g., the trench).

[0037] In several embodiments, a process is used to clean and / or etch the bottom of the trench, which includes depositing a flowable film on the bottom of the trench but not on the sidewalls of the trench. The flowable film can be, for example, a liquid-flowable chemical vapor deposition (CVD) film. Liquid-flowable CVD films can be used to fill or partially fill trenches with aspect ratios up to 30:1. In several embodiments, the flowable film lacks carbon in the film, which hinders transistor isolation and causes voltage shift and leakage. A flowable film can be formed by depositing a liquid precursor flowing to a low point and then reacting the liquid precursor with one or more other materials to form the film.

[0038] In other embodiments, the flowable membrane can be formed by introducing reactants and precursors into a chamber, such that the reactants are present in the gas phase within the chamber and form the flowable membrane. The flowable membrane then flows into a trench and deposits at the bottom of the trench.

[0039] After the flowable film is formed, a self-assembled monolayer (SAM) is formed. The SAM may not be formed on the flowable film, but may be formed on other exposed surfaces. Therefore, in several embodiments, the SAM can be formed anywhere except on the flowable film at the bottom of the trench. After the SAM is formed, the flowable film can be removed from the bottom of the trench. An etching process can then be performed, which can be highly selective for the material at the bottom of the trench (e.g., Si or natural oxides such as SiO2) compared to the SAM.

[0040] Figure 3 This describes the process for forming a self-assembled monolayer (SAM) on surface 305 of substrate 310. Substrate 310 may represent, for example, a semiconductor wafer on which one or more trenches are formed (e.g., trenches formed by alternating stacks of materials such as Si and SiO2). As understood in the art, the SAM can be an organic molecule in which molecules spontaneously form on the surface through adsorption and are organized into more or less large-scale ordered domains. In some embodiments, the molecules forming the SAM do not strongly interact with the substrate. In other embodiments, the molecules may have head groups that have a strong affinity for the substrate and anchor the molecules to the substrate. https: / / en.wikipedia.org / wiki / Self-assembled_monolayer-cite_note-Love-1 Article 310 and surface 305 may be made of, for example, Si, SiO2, SiG, SiN or any other material or combination of materials.

[0041] Each individual chemical reaction between the precursor and the surface is referred to as a "half-reaction." During each half-reaction, the precursor is pulsed onto the surface for a duration sufficient to allow the precursor to fully react with the surface. This reaction is self-limiting because the precursor will only react with a limited number of available reaction sites on the surface, thereby forming a uniform, continuous adsorption layer on the surface. Any site that has already reacted with the precursor becomes unusable for further reactions with the same precursor unless and / or until the reacted site is treated to form new reaction sites on the uniform, continuous coating. Exemplary treatments may be plasma treatment, treatments by exposing the uniform, continuous adsorption layer to free radicals, or the introduction of different precursors capable of reacting with the newly adsorbed uniform, continuous film layer on the surface.

[0042] exist Figure 3In this process, a substrate 310 having surface 305 can be introduced to a first precursor 360 for a first duration until a first half-reaction between the first precursor 360 and surface 305 partially forms layer 315 by forming an adsorption layer 314. In several embodiments, the adsorption layer 314 is not formed on a flowable film, which may have already been deposited on one or more portions of surface 305 (e.g., at the bottom of a trench formed on surface 305). Subsequently, the article 310 can be introduced to a second precursor 365 (also referred to as a reactant) to induce a second half-reaction, reacting with the adsorption layer 314 to fully form layer 315. Layer 315 may be uniform, continuous, and conformal. The substrate 310 may be alternately exposed to the first precursor 360 and the second precursor 365 up to x times to achieve a target thickness of layer 315. For example, x may be an integer from 1 to 100.

[0043] Surface reactions (e.g., half-reactions) proceed sequentially. Before introducing new precursors, the chamber where the ALD or MLD treatment occurs can be purged with an inert carrier gas (e.g., nitrogen or air) to remove any unreacted precursors and / or surface precursor reaction byproducts. At least two precursors can be used in several embodiments. In some embodiments, more than two precursors can be used to grow films with the same composition (e.g., multilayer SAMs grown in a stacked manner). In other embodiments, different precursors can be used to grow different films with different compositions.

[0044] ALD or MLD treatments can be performed at various temperatures depending on the type of ALD or MLD treatment. The optimal temperature range for a particular ALD or MLD treatment is referred to as the "ALD temperature window" or "MLD temperature window." Temperatures below the temperature window may result in poor growth rates and non-ALD type deposition. Temperatures above the temperature window may cause pyrolysis of the product or rapid desorption of precursors. The temperature window can range from about 20°C to about 400°C. In some embodiments, the MLD temperature window is between about 200-350°C.

[0045] ALD / MLD processing allows for the formation of conformal films with uniform thickness on articles and surfaces with complex geometries, high aspect ratios, pores, and three-dimensional structures. Sufficient exposure time of the precursor to the surface allows it to disperse and fully react with the entire surface, including all its complex three-dimensional features. The exposure time required to achieve conformal ALD in high aspect ratio structures is proportional to the square of the aspect ratio and can be predicted using modeling techniques. Furthermore, ALD technology is more advantageous than other commonly used coating techniques because it allows for on-demand, in-situ synthesis of specific compositions or formulations, eliminating the need for lengthy and complex source material fabrication (e.g., powder feedstocks and sintered targets).

[0046] Using ALD / MLD technology, membranes such as self-assembled monolayers (SAMs) can be grown by properly arranging precursors.

[0047] In previous embodiments, chemical passivation or directional etching was used to selectively etch the bottom surface of the trench without etching the sidewalls.

[0048] Figure 4 This is a flowchart illustrating a method 400 for selectively etching or cleaning a substrate according to an embodiment of the present disclosure. In method 400, at block 401, a patterned substrate is received. The substrate may be patterned to have at least one trench. The at least one trench may have a top surface, at least one sidewall surface, and a bottom surface. For example, the substrate may have, as shown below, a patterned substrate. Figure 5 The groove shown. Figure 5 In this embodiment, a substrate 507 having a trench 508 is formed in frame 501. The substrate 507 may include silicon. The trench 508 has a top surface 511, at least one sidewall 509, and a bottom surface 510. The bottom surface 510 may have an epitaxial silicon oxide (epi) layer 510a formed during or after the formation of the trench 508. In some embodiments, at least one sidewall 509 has a layer 509a formed on the sidewall 509 that is different from the epitaxial layer 510a. In one embodiment, layer 509a may include silicon nitride (SiN). In other embodiments, layer 509a may be silicon, damaged silicon nitride, silicon oxide, or a low-kb material. As understood herein, the term "low-kb material" refers to a material having a small relative permittivity (k, kappa) relative to silicon dioxide. The method 400 of this disclosure allows removal of the epitaxial layer or another layer at the bottom of the trench 508 without etching the sidewall 509.

[0049] Return to reference Figure 4 After receiving the patterned substrate, a polymer film is deposited onto the bottom surface of at least one trench of the substrate. This can be achieved... Figure 5 As seen in frame 502, a polymer film 512 is deposited on the bottom surface in frame 502. Capillary action can be used to deposit the polymer film 512. Low vapor pressure and low reactivity are advantageous when using capillary action. Furthermore, for capillary action to be used, the chamber should be below the boiling point of the polymer film 512, allowing the polymer film 512 to condense at the bottom of the trench. The polymer film 312 can be deposited to a target height in the trench 308. The target height can be approximately 1 nm to approximately 100 nm, approximately 10 nm to approximately 90 nm, approximately 20 nm to approximately 80 nm, approximately 30 nm to approximately 70 nm, approximately 40 nm to approximately 60 nm, or approximately 45 nm to approximately 55 nm. The polymer film 512 can be deposited by allowing the film to flow to the bottom surface 510 of the trench.

[0050] In several embodiments, the polymer film 512 is formed by a flowable film deposition process (such as flowable CVD). In such a process, a liquid precursor can be deposited on a substrate, which can flow to low points in the substrate (e.g., the bottom of a trench).

[0051] In some embodiments, the polymer film 512 may include a carbon-based compound. The carbon-based compound may include a material or may be formed from a precursor selected from general formula A.

[0052]

[0053] In this embodiment, general formula A includes two reactive groups "-Y" arranged in a para position around a central aromatic ring. In one embodiment, the -Y groups may include reactive groups such as hydroxyl, aldehyde, ketone, acid, amino, isocyanate, thiocyanate, or acyl chloride groups. In other embodiments, two or more, three or more, four or more, five or more -Y groups may be present around the aromatic ring. Additional embodiments may also include: in the carbon-based compound and / or precursor, each -Y group is the same reactive group; at least two -Y groups are different reactive groups; and all -Y groups are different reactive groups, as well as other combinations of -Y groups. Specific examples of carbon-based compounds or precursors include hydroquinone, terephthalaldehyde, terephthaloyl chloride, and p-phenylenediamine.

[0054] In some embodiments, the polymer film 512 may comprise a material or may be formed from a precursor selected from general formulas 1 and 2, and may use materials such as... Figure 3 The MLD process described herein is delivered to the chamber alternately in a pulsed manner. The MLD temperature window can be below 150°C.

[0055] In various implementations, general formula 1 can be:

[0056]

[0057] Where R can be H, alkyl, or aryl, and R' can be Cl, Br, IOR, OH, HNR2, Si(NCO)4, Si(NCS)4, or

[0058]

[0059] R can be H, alkyl, or aryl, and R' can be Cl, Br, IOR, OH, or HNR2.

[0060] In several implementations, general formula 2 can be...

[0061]

[0062] Wherein, R, R', and R" can each independently be H, alkyl, or aryl; or

[0063]

[0064] R, R', and R" can each be H, alkyl, or aryl independently.

[0065] In some embodiments, the polymer membrane 512 may be terephthalaldehyde. It has been found that terephthalaldehyde itself may be effective by adjusting the pulse treatment (e.g., by adjusting the temperature of the pulse treatment), without the need for amines.

[0066] In some embodiments, the polymer film 512 may be a flowable film that flows to the bottom surface 510 of the trench 508 during the deposition of the polymer film 512 in the frame 502. The deposition of the polymer film 512 may occur at a temperature within a target temperature range. The target temperature range may be about 0°C to about 400°C, about 25°C to about 300°C, about 50°C to about 250°C, or about 75°C to about 200°C, or about 200°C to about 400°C, about 100°C to about 300°C, or any value or subrange not disclosed herein. The polymer film 512 flows to the bottom surface 510 of the trench 508 without adhering to the sidewall 509.

[0067] A purge gas may also be applied during the deposition of the polymer film 512. The purge gas can be any inert gas, such as nitrogen, argon, or helium. In several embodiments, the deposition of the polymer film can be performed using molecular layer deposition (MLD) or chemical vapor deposition (CVD) processes.

[0068] return Figure 4 After depositing the polymer film onto the bottom surface of the trench, a second film is selectively formed on a layer of the substrate. The second film can be a barrier film. In block 403, the second film is selectively formed on a layer of the substrate, but not on the polymer film. That is, the second film can be formed on the top surface of at least one trench, on at least one sidewall of at least one trench, or a combination of both. This enables… Figure 5 This can be seen in box 503. If it can be seen from... Figure 5 As seen, a second film 513, i.e., a barrier film, is formed on layer 509a of the substrate. The second film 513 may include a self-assembled monolayer (SAM) not formed on the polymer film 512. In various embodiments, the second film 513 is formed using ALD or MLD processes, such as those described above. Figure 3 As described. In other embodiments, chemical passivation may be used to form the second film 513.

[0069] In several embodiments, the second membrane 513 may include at least one of silylamide, silyl halide, silyl alkoxide, or cyclic silylamide. Silylamide is a compound according to general formula III, silyl halide is a compound according to general formula IV, silyl alkoxide is a compound according to general formula V, and cyclic silylamide is a compound having C3-C8 rings.

[0070] R n Si(NR'2) (4-n) Formula III

[0071] In general formula III, R is independently C1-C. 18 Alkyl, C1-C 18 alkenyl, C1-C 18 alkynyl group, C1-C 18 Aliphatic or C1-C 18 Aromatic, and n = 1-3;

[0072] R n SiX (4-n) Formula IV

[0073] In general formula IV, R is independently C1-C. 18 Alkyl, C1-C 18 alkenyl, C1-C 18 alkynyl group, C1-C 18 Aliphatic group, C1-C 18 Aromatics

[0074] X is Cl, F, Br, or I, and n = 1-3; and

[0075] R n Si(OR') (4-n) General formula V

[0076] In the general formula V, R is independently C1-C. 18 Alkyl, C1-C 18 alkenyl, C1-C 18 alkynyl group, C1-C 18 Aliphatic or C1-C 18 Aromatic, and n = 1-3.

[0077] In some embodiments, silylamides can be used for SiO functionalization of the surface. In other embodiments, aldehydes can be used as a second film if SiN functionalization is possible. In yet another embodiment, silyl chlorides can be used for the functionalization of both SiN and SiO.

[0078] The second membrane 513 may be selectively formed on the surface of the trench 508, but not on the polymer membrane at the bottom of the trench. As shown in box 503, the second membrane 513 may be selectively formed on the top surface 511 and sidewall 509 of the trench 508, but not on the polymer membrane 512. Alternatively, the second membrane 513 may be selectively formed only on the sidewall 509 of the trench 508.

[0079] In an alternative embodiment, because the second membrane material has a selective window, the second membrane 513 can be repeatedly formed, ensuring that the sidewall surface is completely or almost completely covered by SAM. That is, depending on the chemicals used, gaps may exist when the second membrane 513 or SAM is applied to the sidewall, so multiple cycles can be performed. Therefore, the second membrane 513 or SAM is selective, such that it forms only on the sidewall.

[0080] Return to reference Figure 4 The flowchart shows that after the second film is formed on the substrate, the polymer film is subsequently removed from the bottom surface of the trench in frame 404. This is in Figure 5 As shown in box 504, it will be performed here. If it is possible to... Figure 5 As seen, after the second film is formed, the polymer film 512 is removed from the bottom surface 510 of the trench. In several embodiments, the polymer film can be removed by heating the substrate. The substrate can be heated within the boiling point range of the polymer film 512. The boiling point range can be from about 200°C to about 400°C, or from about 250°C to about 350°C. The substrate can be heated for about 5 minutes to about 30 minutes, about 10 minutes to about 25 minutes, or about 15 minutes to about 20 minutes. As a result of heating the substrate, the polymer film can be converted into a gas, which can be pumped out from the chamber in which the substrate is processed.

[0081] In some embodiments, plasma can be used to remove the polymer film. For example, the substrate can be exposed to plasma containing H2, NF3, Ar, He, N2, O2, and / or mixtures thereof. The plasma can react with the polymer film to form a gas, which can be pumped out from a chamber containing the substrate.

[0082] If it can be Figure 4 As seen, after the polymer film is removed in box 404, an etching process is then performed on the substrate in box 405. This is in Figure 5The bottom surface 510 of trench 508 can be etched using etching chemicals. During the etching of the bottom surface 510 of trench 508, a second film 513 protects the sidewalls from the etching chemicals, i.e., selectively etching the substrate. During the etching process, epitaxial oxides (e.g., epitaxial silicon dioxide) can be removed from the bottom surface. In some embodiments, ammonia and / or hydrofluoric acid can be used to perform the chemical etching process. Other chemicals that can be used include, but are not limited to, ammonia and water, NHF, NH4F, hydrogen fluoride, or hydrogen chloride. In several embodiments, the etching process is a plasma etching process. In several embodiments, the etching process is a wet etching process. The etching process can also be isotropic etching or anisotropic etching.

[0083] If it can be Figure 4 As seen, after the etching process is performed, the second film is then removed from the substrate in frame 406. This also enables... Figure 5 As seen in box 506, the second film 513 is removed from the trench sidewalls. The second film 513 can be removed by an additional chemical etching process using one of the chemicals described above. Therefore, after undergoing selective etching, the trench 508 of the substrate does not have an epitaxial layer and retains the trench profile because the trench is protected by SAM during the etching process.

[0084] Chemical etching can be performed using ammonia and hydrofluoric acid or ammonium fluoride. Other chemicals that can be used include, but are not limited to, ammonia and water, NHF, NH4F, hydrogen fluoride, or hydrogen chloride.

[0085] In one embodiment, ammonium fluoride can be used to perform the etching process. When SAM forms on the sidewalls, the carbon-based groups prevent the ammonium fluoride from interacting with the sidewalls. Therefore, the carbon-based groups act as a barrier in the chemical etching process of the trench.

[0086] The foregoing description sets forth numerous specific details, such as examples of particular systems, components, methods, etc., to provide a good understanding of several embodiments of the invention. However, it will be apparent to those skilled in the art that at least some embodiments of the invention may be practiced without these specific details. In other instances, known components or methods are not described in detail or are presented in the form of simple block diagrams to avoid unnecessarily obscuring the invention. Therefore, the specific details set forth are merely exemplary. Specific embodiments may differ from these exemplary details and are still considered to be within the scope of the invention.

[0087] Throughout this specification, references to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Additionally, the term "or" is intended to indicate an inclusive "or" rather than an exclusive "or." When the terms "about" or "approximately" are used herein, this is intended to indicate that the precise range of the presented nominal values ​​is within ±10%.

[0088] Although the operations of the methods described herein are shown and described in a specific order, the order of operations for each method can be changed, such that some operations can be performed in reverse order, or that some operations can be performed at least partially synchronously with other operations. In another embodiment, the instructions or sub-operations of different operations can be intermittent and / or alternating.

[0089] It should be understood that the above description is intended to be illustrative and not restrictive. Many other embodiments will be apparent to those skilled in the art upon reading and understanding the above description. Therefore, the scope of the invention should be determined by reference to the appended claims and the full scope of the equivalents conferred by those claims.

Claims

1. A method comprising: placing a substrate into a chamber, the substrate comprising a layer, the layer comprising at least one trench formed in the layer, the at least one trench having a top surface, a bottom surface, and at least one sidewall; depositing a polymer film on the bottom surface of the at least one trench without depositing the polymer film on the at least one sidewall of the at least one trench, wherein the polymer film is a flowable film that flows to the bottom surface of the at least one trench at a temperature within a target temperature range during deposition of the flowable film; selectively forming a second film on the layer without forming the second film on the polymer film; removing the polymer film from the bottom surface of the at least one trench; and etching the bottom surface of the trench using an etching chemistry, wherein the second film protects the at least one sidewall from the etching chemistry.

2. The method of claim 1, wherein the second film comprises a self-assembled monolayer (SAM) that is not formed on the polymer film.

4. The method of claim 1, wherein the layer comprises damaged silicon nitride.

3. The method of claim 1, wherein the layer comprises silicon, silicon nitride, silicon oxide, or a low-k material, wherein the substrate comprises silicon. material, wherein the substrate comprises silicon.

5. The method of claim 1, wherein the bottom surface has a U-shaped profile and comprises the substrate. removing the second film after performing the etching.

6. The method of claim 1, further comprising:

7. The method of claim 1, wherein the step of removing the polymer film comprises at least one of heating the polymer film or exposing the polymer film to a plasma.

8. The method of claim 1, wherein the polymer film comprises a carbon-based compound.

9. The method of claim 8, wherein the carbon-based compound comprises at least one precursor selected from Formula 1 and Formula 2, wherein Formula 1 is one of: wherein R is H, alkyl, or aryl, and R' is CI, Br, I OR, OH, H, NR2, Si(NCO)4, Si(NCS)4, or wherein R' is CI, Br, I OR, OH, H, or NR2; and wherein Formula 2 is one of: R, R', and R" are each independently H, alkyl, or aryl; or wherein, wherein R, and R' are each independently H, alkyl, or aryl.

10. The method of claim 8, wherein the carbon-based compound comprises a precursor selected from Formula A: Y is a hydroxyl, aldehyde, ketone, acid, amino, isocyanate, isothiocyanate, or acyl chloride group. wherein, 11. The method of claim 8, wherein the carbon-based compound is terephthaldehyde.

12. The method of claim 1, wherein the second film comprises at least one of a silyl amide, a silyl halide, or a silyl alkoxide.

13. The method of claim 12, wherein the silyl amide is a cyclic silyl amide. ​ 14. The method of claim 12, wherein the silyl amide is a compound according to Formula III or a cyclic silyl amide having a C3-C8 ring, the silyl halide is a compound according to Formula IV, and the silyl alkoxide is a compound according to Formula V: R n Si(NR’2) (4-n) General formula III, wherein, In Formula III, each R is independently a C1-C18 alkyl, C1-C18 alkenyl, C1-C18 alkynyl, C1-C18 aliphatic, or C1-C18 aromatic, and n = 1-3; R n SiX (4-n) General Formula IV, wherein in General Formula IV, each R is independently a C1-C18 alkyl, C1-C18 alkenyl, C1-C18 alkynyl, C1-C18 aliphatic, C1-C18 aromatic, X is Cl, Br, or I, and n = 1-3; and R n Si(OR') (4-n) General Formula V, wherein in General Formula V, each R is independently a C1-C18 alkyl, C1-C18 alkenyl, C1-C18 alkynyl, C1-C18 aliphatic, or C1-C18 aromatic, and n = 1-3.

15. The method of claim 1, wherein the at least one sidewall of the at least one trench is protected from the etch chemistry by the second film, thereby not being etched.

16. The method of claim 1, further comprising: oxide is removed from the bottom surface of the at least one trench during the etching.

17. The method of claim 1, wherein the etch chemistry comprises ammonium fluoride.

18. A method comprising: placing a substrate into a chamber, the substrate comprising a layer, the layer comprising at least one trench formed in the layer, the at least one trench having a top surface, a bottom surface, and at least one sidewall; depositing a polymer film on the bottom surface of the at least one trench without depositing the polymer film on the at least one sidewall of the at least one trench, wherein the polymer film is a flowable film that flows to the bottom surface of the at least one trench at a temperature within a target temperature range during deposition of the flowable film; selectively forming a second film on the layer without forming the second film on the polymer film, removing the polymer film from the bottom surface of the at least one trench; and cleaning the bottom surface.

19. The method of claim 18, wherein the polymer film is p-xylylene, and the second film comprises a self-assembled monolayer (SAM) that is not formed on the polymer film.

20. A method comprising: placing a substrate into a chamber, the substrate comprising a layer, the layer comprising at least one trench formed in the layer, the at least one trench having a top surface, a bottom surface, and at least one sidewall; depositing a polymer film on the bottom surface of the at least one trench without depositing the polymer film on the at least one sidewall of the at least one trench, wherein the polymer film is a flowable film that flows to the bottom surface of the at least one trench at a temperature within a target temperature range during deposition of the flowable film; and selectively forming a second film on the layer without forming the second film on the polymer film; removing the polymer film from the bottom surface of the at least one trench; performing an etch process, wherein the etch process comprises applying ammonium fluoride to the substrate; wherein the step of performing the etch process selectively interacts with the bottom surface of the at least one trench and does not interact with the top surface and the at least one sidewall. ​

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