Selective etching of the substrate

Abstract

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

Description

[Technical Field]

[0001]

[0001] Embodiments of the present disclosure generally relate to methods for etching a substrate in which a flowable polymer film is used to enable improved etch selectivity between different regions of the substrate. [Background technology]

[0002]

[0002] In the semiconductor industry, devices are produced by numerous manufacturing processes that produce structures of ever-decreasing size. As device geometries shrink, it becomes more difficult to control process uniformity and device repeatability, especially in upstream processes.

[0003]

[0003] Integrated circuits are made possible by processes that create intricately patterned layers of material on a substrate surface. Creating patterned materials on a substrate involves controlled methods of forming and removing exposed material. For example, in gap-fill processes, materials may be formed or deposited to fill trenches or other features formed on a semiconductor substrate. Characteristics of trenches or features may include high aspect ratios and reduced critical dimensions, which can make the fill process challenging. For example, because deposition may occur at the top of the trench or feature and along the sidewalls of the trench or feature, continued deposition can pinch off the trench or feature (including between the sidewalls within the trench or feature), creating voids. This can affect device performance and subsequent processing steps.

[0004]

[0004] In current etching processes, substrates can be composed of silicon and silicon nitride. When exposed to air, the substrate may have a bottom comprising silicon oxide (SiO) and sidewalls of silicon oxynitride (SiON). As devices become smaller, the target etching parameters also decrease. To address this issue, selective etching or selective chemical passivation is preferred. Because the bottom and sidewalls comprise similar materials (SiO and SiON), it is difficult to apply selective etching or selective chemical passivation. Therefore, there is a need to improve selective etching of substrates so that smaller target etching parameters can be achieved. Summary of the Invention

[0005] Some embodiments of the present disclosure provide a method for cleaning and etching a sample. The method may include placing a substrate in a chamber. The substrate may include a layer having at least one trench formed therein. The at least one trench includes a top surface, a bottom surface, and at least one sidewall. In some embodiments, the method may include depositing a polymer film on a bottom surface of the at least one trench without depositing the polymer film on at least one sidewall of the at least one trench. In some embodiments, the method may include selectively forming a second film on the layer without forming the second film on the polymer film. In some embodiments, the method may include removing the polymer film from a bottom surface of the at least one trench. In some embodiments, the method may further include etching the bottom surface of the trench with an etching chemical, wherein the second film protects the at least one sidewall from the etching chemical.

[0006] Some embodiments of the present disclosure provide a method for cleaning and etching a substrate. The method may include placing a substrate in a chamber. The substrate includes a layer having at least one trench formed therein, 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 a bottom surface of the at least one trench without depositing the polymer film on 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 and performing an etching process including applying ammonium fluoride to the substrate. The etching process of the method may selectively interact with the bottom surface of the at least one trench and not with the top surface and at least one sidewall.

[0007]

[0007] The present disclosure is illustrated by way of example, and not by way of limitation, in the accompanying drawings, in which like reference numerals indicate like elements. It should be noted that various references to "an" or "one" embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. [Brief explanation of the drawings]

[0008] [Figure 1] 1 illustrates a cross-sectional view of one embodiment of a processing chamber. [Figure 2A] 1 illustrates a cross-sectional view of one embodiment of multiple layers of a sample. [Figure 2B] FIG. 10 shows a cross-sectional view of one embodiment of a sample of multiple layers etched to have a U-shaped profile. [Figure 3] 1 illustrates the deposition process according to various molecular layer deposition techniques. [Figure 4] FIG. 1 is a flow diagram illustrating a method for selectively cleaning a substrate according to one embodiment of the present disclosure. [Figure 5]1 illustrates a trench in a substrate being selectively cleaned according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009]

[0014] In the fabrication of semiconductor devices, polymer films can be used in many structures and processes, such as masking materials, etch-resistant materials, and trench-filling materials, among other applications. More specific applications of polymer films include the formation of hot-implant hard masks and metal gate (MG) cut hard masks, MG fabrication, reverse tone patterning, etc. The present disclosure includes the formation of polymer films on semiconductor substrates using molecular layer deposition (MLD).

[0010]

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

[0011]

[0016] Selectively coating one or more portions of a substrate with different films can improve the substrate profile and improve blowout of critical dimensions of trenches. It has been found that the use of self-assembled monolayers (SAMs) can block and / or protect surfaces from etching. Selectively protecting surfaces from etching allows for the removal of material in selective areas of the trench (e.g., any oxidized surface) while avoiding blowout of critical dimensions (e.g., trench width or cross-sectional profile). The inventors have discovered that the bottom surface of a substrate trench often becomes oxidized, which generally adversely affects the performance of the final product. To remove the oxidized surface, an etching process step can be performed. However, it is not necessary to etch all surfaces at this stage, as this could affect the substrate profile (e.g., trenches formed in or on the substrate).

[0012]

[0017] Therefore, a SAM can be formed on the top surface, the sidewalls, or a combination thereof to protect these surfaces from etching. The inventors have found that depositing a polymer film on the bottom surface of a trench prevents a SAM from forming on the bottom surface, while allowing a SAM to form on the top surface, the sidewalls, or a combination thereof. In embodiments, a SAM consists of an ordered array of spontaneously assembled organic molecules adsorbed on a surface. These molecules typically consist of one or more moieties (head groups) that have an affinity for the substrate and a relatively long, inert, linear portion.

[0013]

[0018] In embodiments, a flowable polymer is deposited on a substrate, but the flowable polymer does not adhere to the trench sidewalls but instead pools at the bottom of the trench. The flowable polymer may solidify or harden at the bottom of the trench surface without forming on the trench sidewalls. The SAM may then not adhere to the polymer selectively deposited at the bottom of the trench. Therefore, the polymer film at the bottom of the trench may be removed after the SAM is selectively formed (e.g., everywhere except the polymer at the bottom of the trench). Etching chemistries may selectively etch the oxide at the bottom of the trench and / or etch the bottom of the trench at a much faster rate than the SAM. Thus, the SAM protects the sidewalls and / or top of the trench from etching, and etching may be performed selectively to the bottom of the trench.

[0014]

[0019] It has been found that selectively etching or cleaning the surface of a trench in a substrate without etching other surfaces of the trench results in a smaller trench width variation in the trench depth of the etched sample (i.e., substrate) compared to conventional plasma etching processes. Thus, the inventors have discovered a method for selectively cleaning or etching the bottom surface of a trench without or with minimal etching of the top and / or sidewalls of the trench.

[0015]

[0020] In embodiments, the SAM and the polymer film have different chemical reactivities, so that the SAM can be selectively formed on surfaces other than the polymer film. Thus, in accordance with aspects of the present disclosure, the SAM can react with surfaces that do not have a polymer film.

[0016]

[0021] Disclosed herein are embodiments of a method for selectively cleaning or etching a substrate, including 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 the substrate is etched. The polymer film can be deposited on the bottom of at least one trench in the substrate so that the second film is not formed on the bottom by the polymer film when the second film is formed on the substrate. It has been found that the polymer film and the second film can have different chemical reactivities to control the selectivity of the film deposition and / or formation.

[0017]

[0022] As used herein, the term "substrate" refers to a surface or portion of a surface upon which a process acts. Those skilled in the art will also understand that when reference is made to a substrate, it may refer to only a portion of the substrate, unless the context clearly indicates otherwise. Furthermore, when reference is made to deposition on a substrate, it may refer to both a bare substrate and a substrate upon which one or more films or features have been deposited or formed.

[0018]

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

[0019]

[0024] The substrate may be exposed to a pretreatment process (polishing, etching, reducing, oxidizing, hydroxylating (or otherwise generating or grafting target chemical moieties to impart chemical functionality), annealing, and / or baking the substrate surface). In addition to direct film treatment on the surface of the substrate itself, the present disclosure also contemplates that any of the disclosed film treatment steps may be performed on an underlying layer formed on the substrate, as disclosed in more detail below. The term "substrate surface" is intended to include such underlying layers, as the context indicates. Thus, for example, when a film / layer or partial film / layer is deposited on a substrate surface, the exposed surface of the newly deposited film / layer is the substrate surface. What a given substrate surface comprises will depend on what film is being deposited as well as the particular chemistry used. In one or more embodiments, the first substrate surface may be a metal, metal oxide, H-terminated Si, or other suitable substrate. x Ge 1-x and the second substrate surface may be composed of a Si-containing dielectric, or vice versa. In some embodiments, the substrate surface may include specific functionality (e.g., —OH, —NH, etc.).

[0020]

[0025] Referring now to the drawings, FIG. 1 is a cross-sectional view of a processing chamber 100 (e.g., a semiconductor processing chamber) having one or more chamber components according to an embodiment of the present disclosure. The processing chamber 100 can be used for processes that involve a corrosive plasma environment and / or corrosive chemicals. For example, the processing chamber 100 can be a chamber for a plasma etch reactor (also called a plasma etcher). Examples of chamber components that may be exposed to plasma in the processing chamber 100 include a substrate support assembly 148, an electrostatic chuck (ESC), a ring (e.g., a process kit ring or a shingle ring), chamber walls, a base, a showerhead 130, a gas distribution plate, a liner, a liner kit, a shield, a plasma screen, a flow equalizer, a cooling base, a chamber viewport, a chamber lid, a nozzle, a process kit ring, etc. In an embodiment, the processing chamber 100 is used to perform an etch process on a patterned substrate having a plurality of trenches formed therein.

[0021]

[0026] In one embodiment, the processing chamber 100 includes a chamber body 102 and a showerhead 130 that surround an interior space 106. The showerhead 130 may or may not include a gas distribution plate. For example, the showerhead may be a multi-piece showerhead including a showerhead base and a showerhead gas distribution plate bonded to the showerhead base. Alternatively, in some embodiments, the showerhead 130 may be replaced with a lid and a nozzle, or in other embodiments, the showerhead 130 may be replaced with multiple pie-shaped showerhead compartments and plasma generation units. The chamber body 102 may be fabricated from aluminum, stainless steel, or other suitable materials. The chamber body 102 generally includes a sidewall 108 and a bottom 110. Any of the showerhead 130 (or the lid and / or nozzle), the sidewall 108, and / or the bottom 110 may include a multi-layer plasma-resistant coating.

[0022]

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

[0023]

[0028] An exhaust port 126 may be defined within the chamber body 102 and may connect the interior volume 106 to a pumping system 128. The pumping system 128 may include one or more pumps and a throttle valve, which are utilized to evacuate the interior volume 106 of the processing chamber 100 and regulate the pressure within the interior volume 106.

[0024]

[0029] The showerhead 130 may be supported on the sidewall 108 of the chamber body 102 and / or on top of the chamber body. The showerhead 130 (or lid) may be openable to allow access to the interior region 106 of the processing chamber 100 and, when closed, may provide a seal to the processing chamber 100. A gas panel 158 may be coupled to the processing chamber 100 to supply process and / or cleaning gases to the interior region 106 via the showerhead 130 or lid and nozzles. Examples of process gases that may be supplied by the gas panel 158 and used to process 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, as well as other gases such as O2 or NO, among others. 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). The showerhead 130 includes a plurality of gas supply holes 132 throughout. The showerhead 130 can be or include aluminum, anodized aluminum, an aluminum alloy (e.g., Al6061), or anodized aluminum alloy. In some embodiments, the showerhead includes a gas distribution plate (GDP) bonded to the showerhead. The GDP can be, for example, Si or SiC. The GDP can further include a plurality of holes that align with the holes in the showerhead.

[0025]

[0030] The substrate support assembly 148 is disposed within the interior space 106 of the processing chamber 100 below the showerhead 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 that secures the substrate 144 during processing, a metal cooling plate bonded to the electrostatic chuck, and / or one or more additional components. An inner liner may cover the periphery of the substrate support assembly 148. The inner liner may be a halogen-containing gas-resist material such as Al2O3 or YO3. In some embodiments, the substrate support assembly, portions of the substrate support assembly, and / or the inner liner may be coated with a metal layer and a barrier layer.

[0026]

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

[0027]

[0032] FIG. 2A is a cross-sectional view of article 200 including substrate 206. In some embodiments, article 200 can have a stack of layers (e.g., alternating layers of two or more materials). The stack of layers can include a stack of silicon (Si) layers, silicon germanium (SiGe) layers, silicon nitride (SiN) layers, silicon dioxide (SiO2) layers, etc. In embodiments, the stack includes a stack of alternating layers of two or more of the foregoing materials (e.g., an alternating stack of Si and SiGe or an alternating stack of Si and SiO2). In one embodiment, article 200 corresponds to substrate 144 of FIG. 1. Substrate 206 includes Si layers 260a-f arranged in stack 290. In some embodiments, Si layers 260a-f can be in the form of nanosheets (e.g., layers having nm-scale thicknesses). In one embodiment, all of Si layers 260a-f have approximately the same thickness. Alternatively, Si layers 260a-f can have different thicknesses.

[0028]

[0033] A patterned mask 280 (also called an etch mask) may cover the top layer 260a of the stack 290. The patterned mask 280 may be a soft mask or a hard mask. Some hard masks that may be used include polycrystalline silicon hard masks and metal hard masks, such as tungsten hard masks or titanium nitride hard masks. The patterned mask 280 includes open regions 270 that expose the underlying layers to etching chemicals during the etching process. The patterned mask 280 further includes covered regions that protect the underlying layers from the etching chemicals. Areas of the stack 290 below the open regions 270 that are not protected by the patterned mask 280 may be subject to the etching process.

[0029]

[0034] Article 200 can be etched through patterned mask 280 to form cavities or trenches that approximate the shape of the openings in patterned mask 280. The etchant will typically also etch patterned mask 280 at some etch rate.

[0030]

[0035] FIG. 2B shows a cross-sectional view of an article 204 including a substrate 206 having a stack of layers 260a-f that has been subjected to an etching process. The etching process can be any etching process (including chemical etching) used in the art. Chemical etching includes using ammonia and hydrofluoric acid to form ammonium fluoride salt. Other chemical etches include, but are not limited to, using ammonia and water, NHF, NHF, hydrogen fluoride, or hydrogen chloride. The process etched a cavity 400 (e.g., a trench) in layers 260a-f. In one embodiment, the cavity 400 has a tapered cross-sectional shape with a U-shaped profile, with the bottom of the cavity being slightly narrower than the top of the cavity. Notably, the sidewalls of the trench or hole formed from the etching process defined in the embodiments herein are nearly vertical, unlike sidewalls produced by previous etching processes.

[0031]

[0036] In embodiments, a native oxide may form at the bottom of the trench. To remove the native oxide, one or more etching or cleaning processes may be performed. However, these etching or cleaning processes may also etch the sidewalls of the trench, which may change the profile of the trench. Additionally or alternatively, after the trench is formed, a further process may be performed to etch the substrate 206, which may be exposed at the bottom of the trench. However, etching the trench bottom (e.g., substrate 206) may also etch the sidewalls of the trench, again changing the profile of the trench walls. This may adversely affect the critical dimensions of the fabricated device. Embodiments described herein enable the bottom of the trench to be cleaned or etched without adversely affecting the profile or critical dimensions of the device (e.g., of the trench).

[0032]

[0037] In embodiments, the bottom of the trench is cleaned and / or etched using a process that includes depositing a flowable film on the bottom of the trench without depositing a flowable film on the sidewalls of the trench. The flowable film may 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 embodiments, the flowable film disrupts transistor isolation due to a lack of carbon in the film, causing voltage shifts and voltage leakage. The flowable film can be formed by depositing a liquid precursor that flows to a low point and then reacting the liquid precursor with one or more other materials to form the film.

[0033]

[0038] In other embodiments, the flowable film can be formed by introducing reactants and precursors into the chamber, where the reactants are present in the vapor phase within the chamber to form the flowable film, which then flows into the trench and deposits on the bottom of the trench.

[0034]

[0039] After formation of the flowable film, a self-assembled monolayer (SAM) is formed. The SAM may not form on the flowable film, but may form on other exposed surfaces. Thus, in embodiments, the SAM may be formed anywhere except on the flowable film at the bottom of the trench. After the SAM is formed, the flowable film may be removed from the bottom of the trench. An etching process may then be performed. This etching process may be more selective to the material at the bottom of the trench (e.g., Si or a native oxide such as SiO2) over the SAM.

[0035]

[0040] FIG. 3 illustrates a process for forming a self-assembled monolayer (SAM) on a surface 305 of a substrate 310. The substrate 310 may represent, for example, a semiconductor wafer with one or more trenches (e.g., trenches formed from a stack of alternating materials such as Si and SiO2) formed therein. As understood in the art, SAMs are organic molecules. The molecules form spontaneously on a surface by adsorption and are more or less organized into large, ordered domains. In some embodiments, the molecules that form the SAM do not strongly interact with the substrate. In other embodiments, the molecules may have a head group that has a strong affinity for the substrate and anchors the molecule to it. https: / / en.wikipedia.org / wiki / Self-assembled_monolayer - cite_note-Love-1. The article 310 and surface 305 may be made of, for example, Si, SiO2, SiGe, SiN, or other materials or combinations of materials.

[0036]

[0041] Each individual chemical reaction between a precursor and a surface is known as a "half-reaction." During each half-reaction, the precursor is pulsed onto the surface for a sufficient time to allow complete reaction with the surface. Because the precursor reacts with only a finite number of available reactive sites on the surface, this reaction is self-limiting, resulting in the formation of a uniform, continuous adsorbed layer on the surface. Sites already reacted with a precursor are unable to further react with the same precursor unless and / or until they undergo a treatment that creates new reactive sites on the uniform, continuous coating. Exemplary treatments include plasma treatment, exposing the uniform, continuous adsorbed layer to radicals, or introducing a different precursor that can react with the latest uniform, continuous film layer adsorbed on the surface.

[0037]

[0042] In FIG. 3 , a substrate 310 having a surface 305 may be exposed to a first precursor 360 for a first period of time until a first half-reaction of the first precursor 360 with the surface 305 forms an adsorbed layer 314, thereby partially forming a layer 315. In embodiments, the adsorbed layer 314 does not form into a flowable film that may have been deposited on one or more portions of the surface 305 (e.g., the bottom of a trench formed on the surface 305). The article 310 may then be exposed to a second precursor 365 (also referred to as a reactant) to effect a second half-reaction, reacting with the adsorbed layer 314 and completely forming the layer 315. The layer 315 may be uniform, continuous, and conformal. To achieve a target thickness of the layer 315, the substrate 310 may be alternately exposed to the first precursor 360 and the second precursor 365 up to x times, where X is an integer between 1 and 100, for example.

[0038]

[0043] Surface reactions (e.g., half-reactions) are performed sequentially. Before introducing a new precursor, the chamber in which the ALD or MLD process occurs can be purged with an inert carrier gas (e.g., nitrogen or air) to remove any unreacted precursor and / or by-products that have reacted with the surface precursor. In embodiments, at least two precursors can be used. In some embodiments, two or more precursors can be used to grow multiple film layers having the same composition (e.g., multiple layers of SAMs can be grown on top of each other). In other embodiments, different precursors can be used to grow different film layers having different compositions.

[0039]

[0044] Depending on the type of ALD or MLD process, the ALD or MLD process can be performed at various temperatures. The optimal temperature range for a particular ALD or MLD process is referred to as the "ALD temperature window" or "MLD temperature window." At temperatures below the temperature window, growth rates are stunted and non-ALD-type deposition may occur. Temperatures above the temperature window may cause thermal decomposition of the article 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 and 350°C.

[0040]

[0045] The ALD / MLD process enables conformal film layers with uniform film thickness on articles, surfaces with complex geometries, pores with large aspect ratios, and three-dimensional structures. Sufficient exposure time of the precursor to the surface allows the precursor to disperse and fully react with the entire surface, including all three-dimensional intricate features. The exposure time required to achieve conformal ALD on high-aspect-ratio structures is proportional to the square of the aspect ratio and can be predicted using modeling techniques. Furthermore, ALD techniques offer advantages over other commonly used coating techniques because they enable the on-demand synthesis of materials with specific compositions or formulations in situ, without the need for the lengthy and laborious preparation of raw materials (e.g., powder feedstocks or sintered targets).

[0041]

[0046] ALD / MLD techniques, for example, allow the growth of films such as self-assembled monolayers (SAMs) by appropriate sequencing of precursors.

[0042]

[0047] In previous embodiments, chemical passivation or directional etching was used to selectively etch the bottom of the trench and not the sidewalls.

[0043]

[0048] FIG. 4 is a flow diagram illustrating a method 400 for selectively etching or cleaning a substrate according to one embodiment of the present disclosure. In method 400, a previously patterned substrate is received in block 401. 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, as shown in FIG. 5, the substrate may have a trench. In FIG. 5, in block 501, a substrate 507 having a trench 508 is formed. The substrate 507 may comprise 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 (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 that is different from the epi layer 510a formed on the sidewall 509. 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-k material. As understood herein, the term "low-k material" refers to a material that has a low dielectric constant (κ) relative to silicon dioxide. The method 400 of the present disclosure allows for removal of an epilayer or another layer at the bottom of trench 508 without etching sidewalls 509.

[0044]

[0049] Returning to FIG. 4, after receiving the patterned substrate, a polymer film is deposited on the bottom surface of at least one trench in the substrate. This can be seen at 502 in FIG. 5. In block 502, a polymer film 512 is deposited on the bottom surface. The polymer film 512 can be deposited using capillary action. Using capillary action benefits from low vapor pressure and low reactivity. Additionally, to utilize capillary action, the chamber must be below the boiling point of the polymer film 512 so that the polymer film 512 can condense at the bottom of the trench. The polymer film 312 can be deposited to a target height of the trench 308. The target height can be about 1 nm to about 100 nm, about 10 nm to about 90 nm, about 20 nm to about 80 nm, about 30 nm to about 70 nm, about 40 nm to about 60 nm, or about 45 nm to about 55 nm. A polymer film 512 can be deposited by flowing the film onto the bottom surface 510 of the trench.

[0045]

[0050] In an embodiment, the polymer film 512 is formed via a flowable film deposition process, such as flowable CVD. In such a process, a liquid precursor may be deposited on the substrate and may flow to low points within the substrate (e.g., the bottom of a trench).

[0046]

[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 Formula A: TIFF0007776674000001.tif28170 wherein Formula A includes two reactive groups “-Y” arranged in para positions around a central aromatic ring. In one embodiment, the -Y groups can include, among other reactive groups, hydroxyl groups, aldehyde groups, ketone groups, acid groups, amino groups, isocyanate groups, thiocyanate groups, or acyl chloride groups. In other embodiments, there can be two or more -Y groups, three or more -Y groups, four or more -Y groups, five or more -Y groups, etc. arranged around the aromatic ring. Additional embodiments can include, among other combinations of -Y groups in the carbon-based compound and / or precursor, each -Y group with the same reactive group, at least two -Y groups with different reactive groups, and all -Y groups with different reactive groups. Specific examples of carbon-based compounds or precursors include hydroquinone, terephthalaldehyde, terephthalic acid chloride, and p-phenylenediamine, among others.

[0047]

[0052] In some embodiments, the polymer film 512 may include a material or be formed from a precursor selected from Formula 1 and Formula 2, as described in Figure 3. These materials or precursors may alternatively be pulsed into the chamber using an MLD process. The MLD temperature window may be less than 150°C.

[0048]

[0053] In embodiments, Formula 1 is: TIFF0007776674000002.tif30170, where R can be H, an alkyl group, or an aryl group, and R' can be Cl, Br, I, OR, OH, H, NR2, may be Si(NCO)4, Si(NCS)4, or TIFF0007776674000003.tif27170, where R is H, an alkyl group, or an aryl group, and R' can be Cl, Br, I, OR, OH, H, or NR2.

[0049]

[0054] In embodiments, Formula 2 is: TIFF0007776674000004.tif28170, where R, R', and R''' may each independently be H, an alkyl group, or an aryl group; or TIFF0007776674000005.tif29170, where R, R', and R'' may each independently be H, an alkyl group, or an aryl group.

[0050]

[0055] In some embodiments, the polymer film 512 may be terephthalaldehyde, which has been found to be effective on its own without the use of an amine by adjusting the pulsing process (e.g., adjusting the temperature of the pulsing process).

[0051]

[0056] In some embodiments, in block 502, the polymer film 512 may be a flowable film that flows to the bottom surface 510 of the trench 508 during deposition of the polymer film 512. 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., about 75° C. to about 200° C., 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 sidewalls 509.

[0052]

[0057] A purge gas may also be provided during deposition of the polymer film 512. The purge gas may be any inert gas, such as nitrogen, argon, or helium. In embodiments, deposition of the polymer film may be performed using a molecular layer deposition (MLD) or chemical vapor deposition (CVD) process.

[0053]

[0058] Returning to FIG. 4 , after the polymer film is deposited on the bottom surface of the trench, a second film is selectively formed on the layer of the substrate. The second film may be a blocking film. In block 403, a second film is selectively formed on the layer of the substrate without forming the second film on the polymer film. That is, the second film may be formed on the top surface of at least one trench, at least one sidewall of at least one trench, or a combination of both. This can be seen in block 503 of FIG. 5 . As seen in FIG. 5 , a second film 513, i.e., a blocking film, is formed on the layer of the substrate 509 a. The second film 513 may include a self-assembled monolayer (SAM) that is not formed on the polymer film 512. In embodiments, the second film 513 is formed using an ALD or MLD process, as described with reference to FIG. 3 . In other embodiments, the second film 513 may be formed using chemical passivation.

[0054]

[0059] In embodiments, the second film 513 can include at least one of a silylamide, a silyl halide, a silyl alkoxide, or a cyclic silylamide, where a silylamide is a compound according to Formula III, a silyl halide is a compound according to Formula IV, a silyl alkoxide is a compound according to Formula V, and a cyclic silylamide is a compound having a C3-C8 ring. R n Si(NR'2) (4-n) Formula III wherein in Formula III, each R is independently C-C 18 Alkyl groups, C1-C 18 Alkene groups, C1-C 18 Alkyne group, C1-C 18 Aliphatic groups, or C1-C 18 It is aromatic and n=1 to 3. R n Six (4-n) Formula IV wherein in Formula IV, each R is independently C-C 18 Alkyl groups, C1-C 18 Alkene groups, C1-C 18 Alkyne group, C1-C 18 Aliphatic group, C1-C18 It is aromatic and X is Cl, F, Br, or I, and n=1 to 3; R n Si(OR') (4-n) Formula V wherein in Formula V, each R is independently C1-C 18 Alkyl groups, C1-C 18 Alkene groups, C1-C 18 Alkyne group, C1-C 18 Aliphatic groups, or C1-C 18 It is aromatic and n=1 to 3.

[0055]

[0060] In some embodiments, silylamides can be used for SiO functionalization of the surface. In other embodiments, aldehydes may be used as the second film, where SiN functionalization may be used. In yet other embodiments, silylchlorides can be used for both SiN and SiO functionalization.

[0056]

[0061] The second film 513 can be selectively formed on the surface of the trench 508 without being formed on the polymer film at the bottom of the trench. As shown in block 503, the second film 513 is selectively formed on the top surface 511 and sidewalls 509 of the trench 508 without being formed on the polymer film 512. Alternatively, the second film 513 may be selectively formed only on the sidewalls 509 of the trench 508.

[0057]

[0062] In an alternative embodiment, because there is a selectivity window for the second film material, the formation of the second film 513 can be repeated to ensure that the sidewall surface is completely or nearly completely covered with the SAM. That is, depending on the chemistry used, multiple cycles may be performed because gaps may occur when applying the second film 513 or SAM to the sidewall. Thus, the second film 513 or SAM has selectivity to form only on the sidewall.

[0058]

[0063] Returning to the flowchart of FIG. 4, after the second film is formed on the substrate, in block 404, the polymer film is removed from the bottom surface of the trench. This is shown in block 504 of FIG. 5 and described herein. As seen in FIG. 5, after the second film is formed, the polymer film 512 is removed from the bottom surface 510 of the trench. In 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, from about 10 minutes to about 25 minutes, or from about 15 minutes to about 20 minutes. Heating the substrate can result in the polymer film transitioning to a gas, which can be pumped out of the chamber in which the substrate is processed.

[0059]

[0064] In some embodiments, the polymer film can be removed using a plasma. For example, the substrate can be exposed to a plasma containing H, NF, Ar, He, N, O, and / or mixtures thereof. The plasma can react with the polymer film to form a gas. This gas can be pumped out of the chamber containing the substrate.

[0060]

[0065] As seen in FIG. 4 , after the polymer film is removed in block 404, an etching process is performed on the substrate in block 405. This is shown in block 505 of FIG. 5 . The bottom surface 510 of the trench 508 may be etched using an etching chemistry. While etching the bottom surface 510 of the trench 508, the second film 513 protects the sidewalls from the etching chemistry (i.e., selectively etches the substrate). During the etching process, epi oxide (e.g., epitaxial silicon dioxide) may be removed from the bottom surface. In some embodiments, the chemical etching process may be performed using ammonia and / or hydrofluoric acid. Other chemicals include, but are not limited to, ammonia and water, NHF, NHF, hydrogen fluoride, or hydrogen chloride. In embodiments, the etching process is a plasma etching process. In embodiments, the etching process is a wet etching process. Furthermore, the etching process may be an isotropic etch or an anisotropic etch.

[0061]

[0066] As seen in FIG. 4, after the etching process is performed, the second film is removed from the substrate in block 406. This can also be seen in FIG. 5, block 506, where the second film 513 is removed from the sidewalls of the trench. The second film 513 can be removed by an additional chemical etching process using one of the chemicals described above. Thus, after going through the selective etching process, the trench 508 in the substrate does not have an epilayer and is protected by the SAM during the etching process, thereby maintaining the trench profile.

[0062]

[0067] The chemical etching process can be performed using ammonia and hydrofluoric acid, or ammonium fluoride. Other chemicals include, but are not limited to, ammonia and water, NHF, NHF, hydrogen fluoride, or hydrogen chloride.

[0063]

[0068] In one embodiment, the etching process can be carried out using ammonium fluoride. Once the SAM is formed on the sidewall, the carbon-based groups prevent the ammonium fluoride from interacting with the sidewall. Therefore, the carbon-based groups act as a blocking agent during the chemical etching process of the trench.

[0064]

[0069] The foregoing description sets forth numerous specific details, such as examples of specific systems, components, methods, etc., to provide a thorough understanding of some embodiments of the present invention. However, it will be apparent to those skilled in the art that at least some embodiments of the present invention may be practiced without these specific details. In other instances, well-known components or methods are not described in detail or are presented in simple block diagram form to avoid unnecessarily obscuring the present invention. Thus, the specific details shown are merely exemplary. Particular implementations may vary from these example details and still be contemplated as being within the scope of the present invention.

[0065]

[0070] References throughout this specification 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. Thus, appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." When the terms "about" or "approximately" are used herein, this is intended to mean that the nominal value presented is accurate to within ±10%.

[0066]

[0071] Although the method steps herein are illustrated and described in a particular order, the order of each method step may be changed so that certain steps can be performed in reverse order or so that certain steps can be performed at least partially concurrently with other steps. In alternative embodiments, instructions of separate steps or substeps may be intermittent and / or alternating.

[0067]

[0072] It should be understood that the above description is intended to be illustrative, and not limiting. Many other embodiments will become apparent to those skilled in the art upon reading and understanding the above description. The scope of the present invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

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

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

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

4. The method of claim 1 , wherein the bottom surface has a U-shaped profile and comprises the substrate.

5. The method of claim 1 , further comprising removing the second film after performing the etching.

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

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

8. The carbon-based compound comprises at least one precursor selected from Formula 1 and Formula 2, wherein Formula 1 is: (wherein R is H, an alkyl group, or an aryl group, and R' is Cl, Br, I, OR, OH, H, NR ２ , Si(NCO) ４ , or Si(NCS) ４ ), and (wherein R' is Cl, Br, I, OR, OH, H, or NR ２ is) and Equation 2 is one of: where R, R', and R''' are each independently H, an alkyl group, or an aryl group; and (wherein R and R′ are each independently H, an alkyl group, or an aryl group).

8. The method of claim 7, wherein the step of:

9. The carbon-based compound is represented by the formula A 8. The method of claim 7, wherein Y is a hydroxyl group, an aldehyde group, a ketone group, an acid group, an amino group, an isocyanate group, a thiocyanate group, or an acyl chloride group.

10. The method of claim 7, wherein the carbon-based compound is terephthalaldehyde.

11. The method of claim 1 , wherein the second film comprises at least one of a silylamide, a silyl halide, a silyl alkoxide, and a cyclic silylamide.

12. 10. The method of claim 1, wherein the at least one sidewall of the at least one trench is not etched as a result of being protected from the etching chemicals by the second film.

13. The method of claim 1 further comprising removing oxide from the bottom surface of the at least one trench during the etching.

14. The method of claim 1 , wherein the etching chemistry comprises ammonium fluoride.

15. placing a substrate in a chamber, the substrate including a layer having at least one trench formed therein, 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, the polymer film being a flowable film that flows onto the bottom surface of the at least one trench during deposition of the flowable film at a temperature within a target temperature range; selectively forming the second film on the layer without forming the second film on the polymer film; Including, The method, wherein the second film comprises a self-assembled monolayer (SAM) that is not formed on the polymer film.

16. 16. The method of claim 15, wherein the polymer film is terephthalaldehyde.

17. placing a substrate in a chamber, the substrate including a layer having at least one trench formed therein, 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, the polymer film being a flowable film that flows onto the bottom surface of the at least one trench during deposition of the flowable film at a temperature within a target temperature range; selectively forming a second film on the layer without forming a second film on the polymer film; removing the polymer film from the bottom surface of the at least one trench; performing an etching process that includes applying ammonium fluoride to the substrate; wherein performing the etching 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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