Etching method that alternates between non-plasma etching process and plasma etching process

Abstract

A method for forming an opening pattern in a substrate, the substrate comprising a film disposed thereon and a patterned mask layer disposed on the film, the method comprising: 1) exposing the substrate to a vapor of a passivation molecule under non-plasma conditions for a certain period of time to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated etching gas and plasma dry etching the substrate with the plasma-activated etching gas to form openings on the patterned mask layer of the film; and 3) repeating steps 1) and 2) until a desired opening pattern is formed in the film; wherein the surface protection layer is also formed on sidewalls of the openings formed in the film, and the passivation molecule has a boiling point of 20°C or higher.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Patent Application No. 17 / 974,246, filed October 26, 2022, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to an etching method that alternates between non-plasma and plasma etching processes using passivation molecules that condense, chemisorb, or chemically react with the surface to form a protective layer on the surface. [Background technology]

[0003] In sequential plasma etching processes, surface modification (activation) and removal (desorption) of energetic materials occur simultaneously. However, this simultaneous process presents challenges because altering plasma parameters to improve one aspect can degrade another. For silicon-based dielectric etching, balancing the ratio of active radicals (e.g., F, Cl) to inactive radicals (e.g., H, CH) is crucial and must be optimized to achieve the appropriate chemical reaction, either forming easily expelled volatile byproducts or forming protective deposits on the remaining surface (selectivity and profile control). However, fluorine-containing reagents typically suffer from undercutting and proximity effects, limiting their effectiveness to the formation of relatively wide, shallow grooves or trenches. Chlorine-containing gas reagents have profile control issues and are subject to phenomena such as black silicon.

[0004] Therefore, new etching chemistries have been constantly innovatively developed to solve etching challenges that may arise from the ever-shrinking device dimensions, the changing materials used (e.g., high-k and low-k dielectrics), the diversification of device architectures (e.g., FinFET and 3D NAND transistors), and the adoption of new packaging approaches (e.g., TSV technology). Regarding this issue, heavy compounds, usually with high boiling points, have been widely investigated in recent years to etch semiconductor materials to form deep and narrow trenches with controlled profiles. Meanwhile, new processes, such as multi-step etching and combined deposition / etching, have been developed to etch structures with higher than desired aspect ratios.

[0005] Plasma etching of high aspect ratio structures is a complex process that utilizes many different fluorocarbon etch gases to control etch rate, selectivity to the mask, and profile control. Sidewall passivation layers are essential for profile control and bowing reduction. The polymers deposited by the fluorocarbon gases are then removed by etching the carbon mask with Ar. + It also helps protect against ion and oxygen radical bombardment. Mask selectivity can be improved by both a surface coating, which increases etch resistance, and a conductive sidewall passivation layer, which improves etch rate.

[0006] US Patent Application Publication No. 20210020450 discloses an etching method according to one embodiment, which includes alternating between a first step and a second step. In the first step, a first gas containing fluorine atoms is introduced without supplying a high-frequency voltage to form a surface layer on the surface of a target cooled to a temperature below the liquefaction temperature of the first gas. In the second step, a second gas that is gaseous at the first temperature and different from the first gas is introduced, and a high-frequency voltage is supplied to generate plasma from the second gas, thereby etching the target by sputtering using the plasma. The first gas is a fluorine-containing gas having the composition formula Cx H y F z The first gas includes a fluoride gas represented by (x≧1, y≧0, z≧2), whereby the first gas is limited to an F-containing gas.

[0007] U.S. Patent Application Publication No. 20210202260 discloses a technique for enabling etching of a film on a substrate while reducing etching at the sidewall surface. The etching method includes forming a protective layer on the surface of a sidewall defining a recess in the substrate. The protective layer includes sulfur atoms. The etching method further includes, after forming the protective layer, etching the film on the substrate to increase the depth of the recess. The protective layer on the surface is formed under plasma conditions. Some examples include CHF3.

[0008] Zhang et al. ("Improved Plasma Resistance for Porous Low-k Dielectrics," ECS J. Solid State Sci. Tech., 4, N3098-N3107, 2015 and PESM 2014, Grenoble, France) disclose the low-damage integration of ultra-low-k porous organosilicate glasses via a pore-filling approach. They introduce the concept of "capillary condensation" to condense liquid precursors into the micropores of low-k dielectric materials even at pressures lower than their vapor pressures (so-called low-k filling). The advantage of pore-filling is that protection is achieved independently of etching byproducts, significantly improving trench sidewall damage. In the low-k filling process, filled samples are prepared in four steps: surface pretreatment, polymer spin-coating, thermal drive-in, and surface cleaning. This takes advantage of the inherent porous structure of low-k materials (no results on non-porous materials have been reported). This is without prejudice to the disclosure of Zhang et al. Pore ​​filling was achieved in several ways: 1) Pore filling using liquid condensation at cryogenic temperatures; 2) Polymers are deposited on the low-k surface by spin-coating a polymer solution. Thermal annealing at temperatures well above the glass transition temperature of the polymer evaporates the solvent and allows the polymer to infiltrate the porous low-k structure.

[0009] U.S. Patent No. 9,543,158 to Nikhil et al. discloses various methods, apparatus, and systems for forming recess features in a dielectric material on a substrate. In some cases, a protective coating is deposited using plasma-assisted atomic layer deposition, modified plasma-assisted atomic layer deposition, or plasma-assisted chemical vapor deposition. U.S. Patent No. 10,170,324 B2 is similar. In these patents, the protective coating is deposited using many different types of precursor reactants and combination reagents to form a deposition layer on the sidewall. This is performed in an etch / deposit cyclic etch format.

[0010] U.S. Pat. No. 10,361,092 describes adding a metal-containing component to an etching process along with a fluorocarbon etching gas, where the metal component is selected from at least one of tungsten (W), tin (Sn), molybdenum (Mo), ruthenium (Ru), titanium (Ti), or tantalum (Ta); the metal source can include WF6, TiCl4, TiF4, SnH4, TaF5, RuF6, and SnCl4.

[0011] U.S. Pat. No. 10,741,407 describes the addition of metal-containing gas WF6 to high aspect ratio etches to improve sidewall protection by reducing or eliminating problematic sidewall notching.

[0012] U.S. Patent Application Publication No. 20210242032 describes a method for depositing a metal-containing protective film on the sidewalls of a feature using a cyclic etching and deposition process, where the protective film is tungsten carbonitride, tungsten sulfide, tin, tin-containing compounds, molybdenum, molybdenum-containing compounds, ruthenium sulfide, aluminum sulfide, zirconium, and zirconium-containing compounds.

[0013] U.S. Patent No. 9,673,058 describes a method for etching features in a silicon oxide-containing film by adding a W (tungsten)-containing gas, such as WF6, WF5Cl, WBr6, W(CO)6, or WCl6, to a carbon-containing passivation gas, such as a hydrocarbon, fluorohydrocarbon, or fluorocarbon gas, to form a sidewall passivation layer containing tungsten and carbon. The addition of W is expected to improve the etching resistance of the sidewall passivation layer.

[0014] U.S. Patent Application Publication No. 20180286707A1 describes a method for etching high aspect ratio structures with a cyclic cryogenic etch process (<-20°C), including: (a) receiving a substrate in a substrate holder; (b) cooling the substrate by cooling a cooling chamber to a temperature of about -20°C or less; and (c) flowing a reactant mixture into the chamber and generating a plasma from the reactant mixture using a plasma source to etch a dielectric material of the substrate to form features in the substrate, wherein the reactant mixture may be an iodine-containing fluorocarbon, a bromine-containing fluorocarbon, an iodine-containing fluoride, HI, HBr, IBr, SF, SO, CS, COS, CF, CF ... 10 , CHF3, and C2HF5. Cryogenic etching temperatures can be used to adjust the sticking coefficients of the various reactants and other species present during the etch.

[0015] US Patent Application Publication No. 20220199418 discloses a method for treating a substrate that includes performing a cyclic plasma etching process that includes two plasma steps, one of which includes silicon molecules. Summary of the Invention [Problem to be solved by the invention]

[0016] Despite the wide range of options available for etching using Si-containing etchants, additional etchants are continually being sought to enable device engineers to tailor etch conditions and manufacturing process requirements to achieve etch goals with the desired etch rate, selectivity to mask, and profile control. [Means for solving the problem]

[0017] A method of forming an aperture pattern in a substrate is disclosed, the substrate including a film disposed thereon and a patterned mask layer disposed on the film, the method comprising: 1) exposing the substrate to a vapor of passivation molecules under non-plasma conditions for a certain period of time to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated etching gas and plasma dry etching the substrate with the plasma-activated etching gas to form openings on the patterned mask layer of the film; and 3) repeating step 1) and step 2) until a desired opening pattern is formed in the film; The surface protective layer is also formed on the sidewalls of the opening formed in the membrane. The disclosed method can include one or more of the following aspects: · Step 1) and step 2) are not performed simultaneously; The vaporization temperature of the passivation molecules is higher than the processing temperature in step 1); The processing temperature in step 1) is the same as the processing temperature in step 2); The processing temperature in step 1) is in the range of -150°C to 100°C; The processing temperature in step 1) is in the range of -50°C to 50°C; The processing temperature in step 2) is in the range of -150℃ to 50℃; The processing temperature in step 2) is 20°C; The passivation molecules have a boiling point above 20°C; · the passivation molecule is selected from the group consisting of halogen-containing silanes, hydrofluorocarbons, I-containing hydrofluorocarbons, N-containing hydrofluorocarbons, and S-containing hydrofluorocarbons; · Passivation molecule is SiH2I2; · The passivation molecules are mixed with an inert gas selected from Ar, N2, Xe, Kr, Ne, or a combination thereof; The etching gas has the formula: C x H y F z (with x=1-6, y=0-3, z=1-10); Etching gases include CF4, C2F4, C2F6, C3F8, C3F6, C4F6, C4F8, and C4F 10 , C5F8, or C6F6, or a C1-C6 hydrofluorocarbon gas selected from CH3F, CH2F2, CHF3, C2H5F, C3H7F, C4H2F6, C3H2F6, or C2HF5; The etching gas is C4F6; The etching gas is CHF3; The processing pressure in step 1) is in the range of 0.001 torr to 50 torr; The processing pressure in step 1) is in the range of 300 mtorr to 1 torr; · The time of step 1) varies from 0.01 seconds to 10,000 seconds; · The time for step 1) varies from 1 second to 60 seconds; · The plasma treatment time in step 2) varies from 0.01 seconds to 10,000 seconds; · The plasma treatment time in step 2) varies from 1 second to 60 seconds; the film is a SiO2, SiN, SiC, SiCN, or SiON layer, or an alternating SiO / SiN or SiO / p-Si layer; · further comprising adding an oxidizer selected from O2, CO, CO2, NO, NO2, and N2O to the plasma-activated etching gas, wherein the oxidizer is plasma-activated; · further comprising purging with an inert gas between exposure steps; further comprising the step of evacuating to a processing pressure using a vacuum pump between exposure steps; and Further comprising the step of evacuating to a base pressure of the vacuum pump using a vacuum pump between the exposing steps.

[0018] Also disclosed is a method of forming an aperture pattern in a substrate, the substrate including a film disposed thereon and a patterned mask layer disposed on an oxide layer, the method comprising: 1) Exposing the substrate to a gas of passivation molecules under non-plasma conditions for a certain period of time to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated etching gas and plasma dry etching the substrate with the plasma-activated etching gas to form openings on the patterned mask layer of the oxide layer; and 3) repeating step 1) and step 2) until a desired oxide opening pattern is formed in the oxide layer; wherein the surface protective layer is also formed on the sidewalls of the openings in the oxide layer. The disclosed method can include one or more of the following aspects: The vaporization temperature of the passivation molecules is higher than the processing temperature in step 1); and The method further includes adding an oxidizer selected from O2, CO, CO2, NO, NO2, and N2O to the plasma-activated etching gas, wherein the oxidizer is plasma-activated.

[0019] Also disclosed is a method of forming an aperture pattern in a substrate, the substrate including a film disposed thereon and a patterned mask layer disposed on the film, the method comprising: 1) Exposing the substrate to SiH2I2 vapor for a certain period of time under non-plasma conditions to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated fluorocarbon or hydrofluorocarbon etching gas and plasma dry etching the substrate with the plasma-activated fluorocarbon or hydrofluorocarbon etching gas to form openings on the patterned mask layer of the film; and 3) repeating step 1) and step 2) until the desired opening pattern is formed in the film; The surface protective layer is also formed on the sidewalls of the openings in the membrane. The disclosed method can include one or more of the following aspects: The vaporization temperature of the passivation molecules is higher than the processing temperature in step 1).

[0020] Labeling and Nomenclature In the following detailed description and claims, a number of abbreviations, symbols and terms that are generally well known in the art are utilized, including the following:

[0021] As used herein, the indefinite article "a" or "an" means one or more.

[0022] As used herein, "about" or "approximately" or "approximately" in the text or claims means ±10% of the stated value.

[0023] As used herein, "room temperature" in the text and claims means about 20°C to about 25°C.

[0024] The term "substrate" refers to one or more materials on which a process is performed. A substrate may refer to a wafer having one or more materials on which a process is performed. A substrate may be any suitable wafer used in the manufacture of semiconductor, photovoltaic, flat panel, or LCD-TFT devices. A substrate may also have one or more layers of different materials already deposited on it from previous manufacturing steps. For example, the wafer may include a silicon layer (including but not limited to, crystalline, amorphous, porous, etc.), a silicon-containing layer (including but not limited to, SiO, SiN, SiON, SiCOH, etc.), a metal or metal-containing layer (including but not limited to, copper, cobalt, ruthenium, tungsten, platinum, palladium, nickel, ruthenium, gold, etc.), or a combination thereof. Furthermore, the substrate may be flat or patterned. The substrate may be an organically patterned carbon iodide layer film. The substrate may include layers of oxides (e.g., ZrO2-based materials, HfO2-based materials, TiO2-based materials, rare earth oxide-based materials, ternary oxide-based materials, etc.) used as dielectric materials in field effect transistor (FET) applications, such as FinFETs, MOFSETs, GAAFETs (gate-all-around FETs), Ribbon-FETs, nanosheets, fork-sheet FETs, complementary FETs (CFETs), MEMS, 3D NAND, MIM, DRAM, or FeRAM device applications, or nitride-based films (e.g., TaN, TiN, NbN) used as electrodes. The substrate may include alternating layers of oxides (e.g., SiO2) and nitrides (e.g., SiN). Those skilled in the art will recognize that the terms "film" or "layer" as used herein refer to a thickness of any material disposed on or extending over a surface, which may be a trench or line. Throughout this specification and claims, the wafer and associated layers thereon are referred to as the substrate. The substrate can be any solid having functional groups on its surface that are susceptible to reaction with the reactive head groups of the self-assembled monolayer (SAM), including, but not limited to, a 3D object or a powder.

[0025] The term "wafer" or "patterned wafer" refers to a wafer having a stack of films on a substrate, where at least the topmost film of the film stack has topographic features or patterns formed in a pre-etch step, and the patterned top film is prepared for pattern etching.

[0026] As used herein, the term "processing" includes the patterning, exposing, developing, etching, depositing, cleaning, and / or by-product removal necessary to form the described structures.

[0027] The terms "depositing" or "deposition" refer to a series of processes in which atomic or molecular-level materials are deposited on a wafer surface or substrate from a gaseous (vapor) state to a solid state as a thin layer. This process involves a chemical reaction and occurs after plasma formation of reactive gases or after thermal activation of reactive gases. The plasma may be, but is not limited to, capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron cyclotron resonance (ECR) plasma, or microwave plasma. Suitable commercially available plasma etch chambers include, but are not limited to, the Lam Research Dual CCP Reactive Ion Etcher Dielectric Etching Product Family sold under the Flex™ trademark, or the Tactras™ or Episode™ UL from Tokyo Electron Limited. Non-plasma exposure steps may be performed in a separate chamber from the plasma exposure step.

[0028] The term "aspect ratio" refers to the ratio of the height of the trench (or opening) to the width of the trench (or diameter of the opening).

[0029] The terms "passivating chemistries, passivation chemistries, passivating chemicals, passivation chemicals" or "passivating molecules" refer to molecules that condense, chemistrolate, or chemically react with a surface to form a protective layer. This passivation layer may be monolayer or multilayer in thickness, depending on the mechanism involved in passivation. Passivation molecules herein have a boiling point of 20° C. or higher.

[0030] The term "evaporation temperature" as used herein refers to the temperature at which a passivation molecule vaporizes at a pressure lower than or different from atmospheric pressure. The vaporization temperature is the boiling point of the passivation molecule at atmospheric pressure.

[0031] It should be noted that the terms "film" and "layer" may be used interchangeably herein. It is understood that a film may correspond to or relate to a layer, and that a layer may be referred to as a film. Furthermore, those skilled in the art will recognize that the terms "film" or "layer," as used herein, refer to a thickness of some material applied or spread over a surface, and that the surface may range from as large as an entire wafer to as small as a trench or line.

[0032] It should be noted that the terms "aperture," "via," "hole," and "trench" may be used interchangeably herein to refer to an opening formed in a semiconductor structure.

[0033] As used herein, the abbreviation "NAND" refers to a "Negative AND" or "Not AND" gate, the abbreviation "2D" refers to a two-dimensional gate structure on a flat substrate, and the abbreviation "3D" refers to a three-dimensional or vertical gate structure in which the gate structures are stacked vertically.

[0034] It should be noted that, herein, the terms "etching gas" and "etchant" may be used interchangeably when the etching gas is in a gaseous state at room temperature and ambient pressure. It is understood that an etching gas may correspond to or relate to an etchant, and an etchant may refer to an etching gas.

[0035] The terms "doping" or "doping" are used interchangeably to refer to the process of incorporating one or more elements into a film by various methods by which the elements may be chemically or physically bonded, and to the process of intentionally incorporating atoms of different elements into the film composition. Elements may be doped into the film interstitially or substitutionally.

[0036] Standard abbreviations for elements from the periodic table are used herein. It should be understood that elements can be represented by these abbreviations (e.g., Si means silicon, N means nitrogen, O means oxygen, C means carbon, H means hydrogen, F means fluorine, etc.).

[0037] Unique CAS Registry Numbers assigned by the Chemical Abstract Service (i.e., "CAS") are provided to identify the particular molecules disclosed.

[0038] As used herein, the term "hydrocarbon" refers to a saturated or unsaturated functional group containing only carbon and hydrogen atoms. As used herein, the term "alkyl group" refers to a saturated functional group containing only carbon and hydrogen atoms. An alkyl group is a type of hydrocarbon. Furthermore, the term "alkyl group" refers to a straight-chain, branched, or cyclic alkyl group. Examples of straight-chain alkyl groups include, but are not limited to, methyl, ethyl, propyl, and butyl groups. Examples of branched alkyl groups include, but are not limited to, t-butyl groups. Examples of cyclic alkyl groups include, but are not limited to, cyclopropyl, cyclopentyl, and cyclohexyl groups.

[0039] Ranges may be expressed herein as from about one particular value and / or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and / or to the other particular value, along with all combinations within said ranges. All ranges described herein are inclusive of their endpoints (i.e., x=1 to 4 or "x ranges from 1 to 4" includes x=1, x=4, and "x=any number therebetween"), regardless of whether the term "inclusive" is used.

[0040] References herein to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, and different or alternative embodiments are not necessarily mutually exclusive of other embodiments. The same applies to the term "implementation."

[0041] As used in this application, the word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word "exemplary" is intended to present concepts in a concrete manner.

[0042] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise specified or clear from the context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A, if X employs B, or if X employs both A and B, then the phrase "X employs A or B" applies to any of the foregoing cases. Furthermore, the articles "a" and "an," as used in this application and the appended claims, should generally be construed to mean "one or more" unless otherwise specified or clear from the context to refer to the singular form.

[0043] "Comprising" in the claims is an open transitional term meaning that the subsequently-specified claim elements are a non-exclusive list (i.e., something else could additionally be included and still remain within the scope of "comprising"). "Comprising" is defined herein to necessarily encompass the more restrictive transitional terms "consisting essentially of" and "consisting of." Thus, "comprising" could be substituted for "consisting essentially of" or "consisting of" and still remain within the scope of "comprising" as expressly defined.

[0044] In the claims, "providing" is defined to mean providing, supplying, making available, or preparing something. Unless there is express language to the contrary in the claims, this step may be performed by any actor.

[0045] For a better understanding of the nature and objects of the present invention, the following detailed description should be read in conjunction with the accompanying drawings, in which like elements are given the same or similar reference numerals. [Brief explanation of the drawings]

[0046] [Figure 1A] FIG. 1A shows an exemplary patterned structure of an oxide hole pattern on a Si substrate or wafer before mask opening. [Figure 1B] FIG. 1B shows an exemplary patterned structure of an oxide hole pattern on a Si substrate or wafer after mask opening. [Figure 2] FIG. 2 is a flow chart of an exemplary embodiment of the disclosed etching method. [Figure 3A-B] Figure 3A illustrates the application of non-plasma etching using SiH2I2 in a HAR dielectric etch process, and Figure 3B illustrates the application of non-plasma etching using fluorocarbon etch gas C4F6 in a HAR dielectric etch process. [Figure 3C] FIG. 3C shows the oxide hole pattern formed in the substrate by non-plasma formation of the surface protective layer and plasma etching of the holes. [Figure 3D] FIG. 3D shows the oxide hole pattern formed in the substrate by removing the non-plasma formed surface protective layer. DETAILED DESCRIPTION OF THE INVENTION

[0047] An etching method is disclosed that includes the use of passivation molecules that condense, chemisorb, or chemically react with the substrate surface to form a surface protective layer without the use of plasma prior to the plasma etching step. The disclosed method includes multiple steps that alternate between step 1) and step 2), where step 1) is exposing the substrate to a vapor of the passivation molecules under non-plasma conditions for a certain period of time to form a surface protective layer on the substrate, and step 2) is plasma dry etching the substrate with the surface protective layer formed thereon using an etching gas or reactive reagent, such as a fluorocarbon or hydrofluorocarbon etching gas, and one or more oxidizing agents. The surface protective layer may or may not be a polymer layer and may or may not be cleanable by existing cleaning methods. At the end of step 2), an additional cleaning step may be added to clean the surface of the substrate using existing cleaning methods known in the art. Cleaning methods include, but are not limited to, plasma cleaning steps using O2 or CF4, or wet cleaning methods including solvents, water, or reagents such as HF. The certain period in step 2) may be in the range of 0.01 seconds to 10,000 seconds, but is not limited thereto, and may be until the surface passivation layer in step 1) is removed. These steps can be cycled repeatedly as necessary. The number of cycles is not limited, and the cycle process can be completed until the surface protective layer is completely etched. Between cycle steps, a purge step may be applied, or a step of pumping down to the processing pressure or the base pressure of the vacuum pump using a vacuum pump may be applied. These steps are performed sequentially, not simultaneously. Step 1) and step 2) are not performed simultaneously.

[0048] The disclosed passivation molecules have boiling points above 20°C or above room temperature. The processing temperature in step 1) may be below the boiling point of the passivation molecules. The processing temperature in step 2) may range from -50°C to 50°C, preferably room temperature or 20°C, which makes the entire process easier to control and commercially cheaper. The processing temperature in step 1) may be the same as the processing temperature in step 2).

[0049] Disclosed passivation molecules include fluorocarbon or hydrofluorocarbon molecules substituted with halogen elements such as Cl, Br, and I (e.g., C x H a F y , x=1-6, a=0-7, y=0-10), and organic or inorganic Si-containing deposition precursors.

[0050] The disclosed passivation molecules can be halogen-containing silanes, hydrofluorocarbons, I-containing hydrofluorocarbons, N-containing hydrofluorocarbons, and S-containing hydrofluorocarbons.

[0051] More specifically, the disclosed passivation molecules with boiling points above 20° C. may be:

[0052] A) Halogen-containing silanes, SiR x F y I z (wherein x+y+z=4, 0≦y≦4, 0≦z≦4, and R is H, C1 to C 10 linear, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted amino and nitrogen-containing alkyl groups of C3-C 10 (selected from cyclic, heterocyclic, aromatic, amino and nitrogen-containing alkyl groups). When x>1, the R termini may be linked to form a cyclic group.

[0053] Examples of known compounds in this category include: [ka] [ka] [ka]

[0054] Some of the above exemplary molecules are listed in Table 1 along with their CAS numbers and boiling points.

[0055] [Table 1]

[0056] [Table 2]

[0057] A disclosed passivation molecule with a boiling point above 20°C is SiH2I2 diiodosilane (DIS, CAS number: 13760-02-6, boiling point: 150°C).

[0058] B) Hydrofluorocarbons, C x H y F z (In the formula, 3≦x≦10, 0≦y≦21, 0≦z≦21);C3~C 10 may be a linear, branched, or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl group.

[0059] An example of a known compound in this category is C4H2F6, cis-1,1,2,2,3,4-hexafluorocyclobutane (CAS number: 22819-47-2, boiling point value: 63°C). [ka]

[0060] C) I-containing hydrofluorocarbons having a boiling point above 20°C, Cn H x F y I z (wherein, 1≦n≦10, 0≦x≦21, 0≦y≦21, 1≦z≦4). Here, C1 to C 10 may be a linear, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted alkyl group. 10 may be a cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl group.

[0061] Examples of known compounds in this category include:

[0062] [Table 3]

[0063] [Table 4]

[0064] D) N-containing hydrofluorocarbons with boiling points above 20°C, C n H x F y N z (wherein, 1≦n≦10, 0≦x≦21, 0≦y≦21, 1≦z≦4). Here, C1 to C 10 may be a linear, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted alkyl group. 10 may be a cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl group.

[0065] E) S-containing hydrofluorocarbons having a boiling point above 20°C, C n H x F y S z (wherein, 1≦n≦10, 0≦x≦21, 0≦y≦21, 1≦z≦4). Here, C1 to C 10may be a linear, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted alkyl group. 10 may be a cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl group.

[0066] The disclosed etching method utilizing passivation molecules includes multiple steps of alternating non-plasma etching steps using passivation molecules and plasma etching steps using etching gases or reactive reagents. The disclosed etching method allows for exploring the unique properties of passivation molecules that have been demonstrated in deposition processes, such as the formation of a surface protective layer (or passivation layer) in the etching process. The etching gas or reactive reagent is preferably a compound having the general formula: x H y F z (x=1-6, y=0-3, z=1-10). The etching gas or reaction reagent may also contain other elements such as I, N, O, S, and Br. Preferred fluorocarbon etching gases are CF4, C2F4, C2F6, C3F8, C3F6, C4F6, C4F8, and C4F 10 C1 to C6 fluorocarbons (C x F y ) Preferred hydrofluorocarbon etching gases are C1 to C6 hydrofluorocarbons (C) such as CH3F, CH2F2, CHF3, C2H5F, C3H7F, C4H2F6, C3H2F6, or C2HF5 molecules. x H a F y , a>0).

[0067] In the disclosed method, the amount of passivation molecules added in the non-plasma etching step can be controlled by the chamber pressure and exposure time. The electrostatic chuck (ESC) temperature in the plasma etching step can affect etching performance, but the non-plasma step does not have a significant effect. The ESC temperature window in the non-plasma etching step is below the vaporization temperature of the passivation molecules (here, at subatmospheric pressure) when the passivation molecules condense on the surface, and is preferably the same as the temperature in the plasma step. The ESC temperature window in the plasma step can be room temperature or 20°C. Advanced ESC temperature control capabilities enable a wider range of ESC temperatures. Depending on the required thickness of the surface protection layer, an ESC temperature lower than the vaporization temperature of the passivation molecules can allow the passivation molecules to adhere or condense on the surface. Alternatively, another option is to add the passivation molecules in the non-plasma etching step at a temperature higher than the vaporization temperature of the passivation molecules, which is sufficient for the passivation molecules to chemisorb or chemically react with the substrate surface. In this case, the passivation molecules can be bound to the surface in a monolayer in the first layer for surface protection, i.e., the protective or passivation layer. A chemical reaction between the passivation molecules and the surface can occur, for example, between the passivation molecules and bonds such as Si-O, Si-OH, or Si-N that are initially present on the surface. A subsequent etching step can be a cleaning step to remove the passivation layer, as shown in FIG. 3D. This step can also be a plasma etching step using exemplary gases such as O2 or CF4 to remove the passivation layer. Because the process pressure is less than 1 atmosphere, the boiling point itself (defined at 1 atmosphere) is not a determining factor in whether true condensation occurs, but there is some possibility that molecules will collide with the surface and undergo a mechanism of adsorption or chemisorption to the surface.

[0068] FIG. 2 is a flowchart of an exemplary embodiment of the disclosed etching method using passivation molecules. Initially, in step 402, a wafer having one or more layers (e.g., one or more silicon-based layers) and a patterned mask layer disposed on the one or more layers is placed in the etching chamber, i.e., reactor or reaction chamber, of a plasma etcher, and the chamber is pumped down to a high vacuum. The reactor here can be a plasma etch, reactive ion etch, capacitively coupled plasma (CCP), inductively coupled plasma (ICP), remote plasma, pulsed plasma, or ECR plasma etcher. Preferably, the reactor is a CCP plasma etcher. The pressure of the etching chamber can vary from 0.001 torr to 1000 torr. Preferably, the pressure of the etching chamber can vary from 1 mtorr to 1 torr. The pressure of the passivation non-plasma step can be different from the pressure of the plasma etching step. The patterned mask layer can be formed with reference to FIGS. 1A and 1B. The patterned mask layer may be an amorphous carbon layer or a silicon material layer containing a dopant element selected from B, N, Si, Al, Cr, Ti, or W. In step 404, the wafer is fixed to an electrostatic chuck (ESC), the ESC temperature is set, and the ESC temperature is allowed to equilibrate. The temperature in this non-plasma etching step can be varied between -150°C and 100°C, preferably between -50°C and 50°C. The temperature in this non-plasma etching step can be below the boiling point of the passivation molecules. In step 406, a passivation molecule gas is flowed or introduced into the etching chamber, a chamber pressure or process pressure is set, and a predetermined exposure time, preferably between 0.01 seconds and 10,000 seconds, more preferably between 1 second and 30 seconds, is maintained, thereby condensing and / or adsorbing the passivation molecules onto the wafer surface to form a surface protection layer or surface passivation layer. Here, an inert gas may be introduced into the etching chamber together with the passivation molecule gas.That is, a mixture of passivation molecule gas and inert gas (Ar, Ne, Kr, Xe, N2) may be introduced into the etching chamber. This process may be a physical condensation or chemical surface reaction that forms a modified layer such as a protective layer on the wafer surface. The flow rate of the passivation molecule gas can be varied from 1 sccm to 10,000 sccm, preferably from 100 sccm to 1,000 sccm. When an inert gas (Ar, Ne, Kr, Xe, N2) is used, the flow rate of the mixture of passivation molecule and inert gas (Ar, Ne, Kr, Xe, N2) can be varied from 1 sccm to 10,000 sccm, preferably from 100 sccm to 1,000 sccm. These flow rates depend on the properties of the molecules and the configuration and size of the chamber. After a certain exposure time, in step 408, the flow of the passivation molecule gas or the mixture of the passivation molecule and an inert gas (e.g., Ar, Ne, Kr, Xe) into the etching chamber is stopped, the remaining gas mixture in the etching chamber is evacuated, and the etching chamber is pumped down to a high vacuum. The flow rate or amount of passivation molecules in the non-plasma etching process can be controlled by the chamber pressure and exposure time. In the next step 410, the plasma etching process is started. If a different ESC temperature from that in step 404 is required, the ESC temperature is set and allowed to equilibrate. The ESC temperature in the plasma etching process may be the same as the ESC temperature in the non-plasma etching process set in step 404. The ESC temperature in the plasma etching process can be in the range of -150°C to 50°C, preferably room temperature or 20°C. Then, a fluorocarbon or hydrofluorocarbon (e.g., C) is introduced. x H y F z, x=1-6, a=0-7, y=0-10) etching gases are flowed or introduced into the etching chamber and equilibrated, and in step 412, an inert gas (e.g., Ar, Ne, Kr, Xe) is optionally flowed into the etching chamber along with the etching gases and equilibrated. Preferred fluorocarbon gases are CF4, C2F4, C2F6, C3F8, C3F6, C4F6, C4F8, C4F 10 , C5F8, or C6F6 x F y The preferred hydrofluorocarbon gas is one or more C1 to C6 C molecules selected from CH3F, CH2F2, CHF3, C2H5F, C3H7F, C4H2F6, C3H2F6, or C2HF5. x H a F yThe numerator (a>0) is used. The flow rate of the fluorocarbon or hydrofluorocarbon etching gas can vary from 1 sccm to 10,000 sccm, preferably from 10 sccm to 100 sccm. In the next step, step 414, the plasma source is turned on to ignite the plasma, and the bias power supply is turned on to set the plasma bias. The plasma process is then continued for a predetermined exposure time, preferably from 0.01 seconds to 10,000 seconds, more preferably from 0.01 seconds to 30 seconds. The source plasma power can vary from 10 W to 20,000 W, preferably from 100 W to 3,000 W. The bias plasma power can vary from 10 W to 100,000 W. The source plasma can be in a continuous mode or a pulsed mode with a pulse frequency of 1 Hz to 10,000 Hz, preferably from 100 Hz to 1,000 Hz. The bias plasma can be in a continuous mode or a pulsed mode with a pulse frequency of 1 Hz to 10,000 Hz. In this step, the etching gas is plasma-activated. The plasma-activated etching gas plasma-dry etches one or more layers of the wafer, thereby forming openings on the patterned mask layer of the one or more layers. After performing the plasma process for a predetermined exposure time, all plasma sources are turned off in step 416. The gases in the etching chamber are then evacuated, and the etching chamber is pumped to high vacuum. The wafer is then removed from the chuck from the ESC in step 418, and the wafer is removed from the etching chamber in step 420. If necessary, steps 404 through 418 can be cycled repeatedly until the desired etching depth of the opening is achieved and a surface protective layer is also formed on the sidewalls of the opening. Note that the predetermined exposure time for the non-plasma etching process and the predetermined exposure time for the plasma dry etching process in each subsequent cycle may be changed. Additional steps may be required to remove the surface protective layer or any other passivation chemicals from the surface of the wafer. These cleaning steps may include plasma or wet processes.Plasma processes may include chemicals such as O2 or CF4. Wet processes may include water, organic solvents, or acids such as HF.

[0069] Any of the above steps can be performed in a static mode or a dynamic mode. A static mode means that the gases flow into a sealed reaction chamber, i.e., the gate valve of the sealed reaction chamber is closed. A dynamic mode means that the gases flow dynamically into the vacuum etching chamber, with the gate valve to the vacuum pump open.

[0070] The enclosed reaction chamber can be any enclosure or chamber in a device in which an etching process is performed, such as, but not limited to, a reactive ion etch (RIE), a capacitively coupled plasma (CCP) with a single or multiple frequency RF source, an inductively coupled plasma (ICP), or a microwave plasma reactor, or any other type of etching system capable of selectively removing portions of a silicon-containing film or generating activated species. Those skilled in the art will recognize that different plasma reaction chamber designs provide different electronic temperature control. Suitable commercially available plasma reaction chambers include, but are not limited to, the Applied Materials magnetically enhanced reactive ion etcher sold under the eMAX™ trademark or the Lam Research Dual CCP reactive ion etcher dielectric etching product line sold under the 2300® Flex™ trademark. The RF power therein can be pulsed to control the plasma characteristics and thereby further improve etching performance (selectivity and damage).

[0071] Alternatively, the plasma-treated reactant may be generated outside the reaction chamber. An MKS Instruments ASTRONi® Reactant Gas Generator may be used to treat the reactant before it enters the reaction chamber. Operating at 2.45 GHz, 7 kW of plasma power, and a pressure ranging from about 0.5 Torr to about 10 Torr, the reactant O2 can be decomposed into two O radicals. Preferably, the remote plasma can be generated at a power ranging from about 1 kW to about 10 kW, more preferably from about 2.5 kW to about 7.5 kW.

[0072] The reaction chamber may contain one or more substrates. For example, the reaction chamber may contain 1 to 200 silicon wafers with diameters ranging from 25.4 mm to 450 mm. The substrates may be any suitable substrate used in semiconductor, photovoltaic, flat panel, or LCD-TFT device manufacturing. Examples of suitable substrates include wafers such as silicon, silica, glass, Ge, SiGe, GeSn, InGaAs, GaSb, INP, or GaAs wafers. The wafers may have multiple films or layers thereon from previous manufacturing steps, including silicon-containing films or layers. The layers may be patterned or unpatterned. Examples of suitable layers include, but are not limited to, silicon (amorphous silicon, p-Si, crystalline silicon, any of which may be further p-doped or n-doped with B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge), silica, silicon nitride, silicon oxide, silicon oxynitride, Si a O b H c C d N e(wherein a>0; b, c, d, e≧0), Ge, SiGe, GeSn, InGaAs, GaSb, InP; mask layer materials such as amorphous carbon with or without dopants, anti-reflective coatings, photoresist materials, metal oxides such as AlO, TiO, HfO, ZrO, SnO, TaO, or metal nitride layers such as AlN, ZrN, SnN, HfN, titanium nitride, tantalum nitride, etc., or combinations thereof; silicon nitride, polysilicon, crystalline silicon, silicon carbide, SiON, SiCN, or combinations thereof, device channel materials such as crystalline silicon, epitaxial silicon, doped silicon, Si a O b H c C d N e (wherein a>0; b, c, d, e≧0) or a combination thereof. The silicon oxide layer may form a dielectric material such as an organic-based or silicon oxide-based low-k dielectric material (e.g., porous SiCOH film). Exemplary low-k dielectric materials are sold by Applied Materials under the trade name Black Diamond II or III. Furthermore, layers containing tungsten or noble metals (e.g., platinum, palladium, rhodium, or gold) may be used. Further, examples of silicon-containing films include Si a O b H c C d N e where a>0; b, c, d, e≧0. Throughout the specification and claims, the wafer and any associated layers thereof will be referred to as the substrate.

[0073] The disclosed passivation molecule vapor and fluorocarbon or hydrofluorocarbon vapor are each introduced into a reaction chamber containing a substrate and a silicon-containing film deposited thereon. The vapors can be introduced into the chamber at a flow rate ranging from about 0.1 sccm to about 1 slm. For example, for a 200 mm wafer size, the vapor can be introduced into the chamber at a flow rate ranging from about 5 sccm to about 50 sccm. Alternatively, for a 450 mm wafer size, the vapor can be introduced into the chamber at a flow rate ranging from about 25 sccm to about 250 sccm. Those skilled in the art will recognize that flow rates may vary from tool to tool.

[0074] The disclosed passivation molecule vapors and fluorocarbon or hydrofluorocarbon vapors may be provided in pure form or as blends with inert gases such as N2, Ar, Kr, Ne, He, Xe, etc., or with solvents. The disclosed passivation molecule vapors and fluorocarbon vapors can be present in various concentrations in the blends.

[0075] Additionally, the disclosed passivation molecules and fluorocarbon or hydrofluorocarbon etching gases are supplied in purity ranging from 95% to 99.999% by volume, which can be purified using standard purification techniques known in the art to remove CO, CO, N, HO, HF, HS, SO, halides, and other hydrocarbons or hydrohalocarbons.

[0076] An inert gas may be introduced into the reaction chamber to maintain the plasma in step 2. The fluorocarbon or hydrofluorocarbon inert gas may be He, Ar, Xe, Kr, Ne, N2, He, or a combination thereof. The etching gas and the inert gas may be mixed prior to introduction into the chamber, with the inert gas comprising about 0.01% v / v to about 99.9% v / v of the resulting mixture. Alternatively, the etching gas may be introduced into the chamber in pulses, while the inert gas may be introduced into the chamber continuously.

[0077] In step 2), the fluorocarbon or hydrofluorocarbon etching gas vapor and the inert gas are activated with a plasma to generate an activated etching gas. The plasma decomposes the etching gas into radical form (i.e., the activated etching gas). The plasma can be generated by applying RF power or DC power. The plasma can be generated with RF power ranging from about 25 W to about 100,000 W. The plasma can be generated remotely or within the reactor itself. The plasma can be generated in a dual CCP or ICP mode, where RF is applied to both electrodes. The RF frequency of the plasma can range from 100 kHz to 1 GHz. Different RF sources with different frequencies can be combined and applied to the same electrode. The plasma RF pulses can further be used to control the fragmentation and reaction of molecules at the substrate. Those skilled in the art will recognize suitable methods and apparatus for such plasma processing.

[0078] The activated etching gas from the chamber exhaust may be measured by a quadrupole mass spectrometer (QMS), optical emission spectrometer, FTIR, or other radical / ion measurement tool to determine the type and number of species generated. If necessary, the flow rates of the etching gas and / or inert gas may be adjusted to increase or decrease the number of radical species generated.

[0079] The disclosed passivation molecules and fluorocarbon or hydrofluorocarbon etching gases may each be mixed with other gases before or within the reaction chamber. Preferably, these gases are mixed prior to introduction into the chamber to ensure uniform concentrations of the incoming gases.

[0080] In another alternative, the vapor of the disclosed passivation molecules and the vapor of the fluorocarbon or hydrofluorocarbon etching gas may each be introduced into the chamber independently of the other gases, for example, if two or more of the gases are reactive or easier to supply independently.

[0081] In another alternative, the vapor of the disclosed passivation molecules and the inert gas, and the vapor of the fluorocarbon or hydrofluorocarbon etching gas and the inert gas, respectively, are the only two gases used during the etching process, where the vapor of the disclosed passivation molecules and the vapor of the fluorocarbon or hydrofluorocarbon etching gas, respectively, may or may not be mixed with the inert gas.

[0082] Exemplary other gases include, but are not limited to, oxidizers such as O2, O3, CO, CO2, NO, NO2, NO2, HO, HO2, COS, SO2, and combinations thereof. The disclosed passivation molecules and oxidizer vapors, and fluorocarbon or hydrofluorocarbon etching gases and oxidizer vapors, respectively, may be mixed together before being introduced into the reaction chamber.

[0083] Alternatively, the oxidizer may be continuously introduced into the chamber, and the vapor of the disclosed passivation molecules and the vapor of the fluorocarbon or hydrofluorocarbon etching gas may be pulsed into the chamber. The oxidizer may comprise from about 0.01% v / v to about 99.99% v / v of the mixture introduced into the chamber (99.99% v / v representing the introduction of nearly pure oxidizer in the alternative to continuous introduction).

[0084] The silicon-containing film and the activated fluorocarbon or hydrofluorocarbon etching gas react to form volatile by-products that are removed from the reaction chamber. The aC mask, anti-reflective coating, and photoresist layer have low reactivity with the activated etching gas. Therefore, the activated etching gas selectively reacts with the silicon-containing film to form volatile by-products.

[0085] The silicon-containing film is anisotropically removed from the substrate by reaction with the activated etching gas. Nitrogen, oxygen, and / or carbon atoms may also be present in the silicon-containing film. Removal may occur by physical sputtering of the silicon-containing film by plasma ions (accelerated by the plasma) and / or by chemical reaction of plasma species to convert Si to volatile species (e.g., SiF x , where x is in the range of 1 to 4).

[0086] The disclosed etching method, which alternates between non-plasma and plasma processes, preferably exhibits high selectivity to the mask and etches oxide layers or alternating layers of SiO and SiN, resulting in a vertical etch profile without bowing or roughness, which is important for 3D NAND applications. Furthermore, the plasma-activated vapor deposits a surface protective layer on the sidewalls, minimizing deformation of the feature profile. For other applications, such as DRAM and 2D NAND, plasma-activated etching gases at different process conditions can selectively etch SiO from SiN. Plasma-activated etching gases can selectively etch SiO and / or SiN from mask layers such as aC, photoresist, p-Si, or silicon carbide; from metal contact layers such as Cu, W, or Ru; or from channel regions made of SiGe or polysilicon regions.

[0087] The disclosed etching methods, which alternate between non-plasma and plasma processes, produce openings in silicon-containing films, such as channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, contact etch, slit etch, self-aligned contacts, self-aligned vias, and supervias. The resulting openings can have aspect ratios ranging from about 1:1 to about 500:1, preferably from about 20:1 to about 400:1, and diameters ranging from about 5 nm to about 500 nm, preferably less than 100 nm. For example, those skilled in the art will recognize that channel hole etching can produce openings in silicon-containing films with aspect ratios greater than 50:1.

[0088] A typical material requiring etching may be SiO. The SiO etching process may involve etching trenches in borophosphosilicate glass (BPSG), tetraethylorthosilicate (TEOS), or low deposition rate TEOS (LDTEOS). The etch stop layer may be silicon nitride or silicon oxynitride (SiON) or polysilicon. The mask material used may be aC, p-Si, or a photoresist material. The iodine-containing etching compounds disclosed herein are utilized to etch SiO, SiN, p-Si, and / or aC substrate films.

[0089] The dielectric layer of the wafer to be etched may include SiN, SiO2, SiC, SiCN, SiON deposited on a Si substrate. The mask layer material may be amorphous carbon (aC) or silicon material doped with other elements such as B, N, Si, Al, Cr, Ti, and W. The fluorocarbon or hydrofluorocarbon gas may be C x H y F zThe fluorocarbon or hydrofluorocarbon molecules may range from 1 to 6, Y to 3, Z to 1 to 10, and may contain other elements such as I, N, O, S, Br, etc. Oxygen (O2) or another oxygen source, such as CO, CO2, NO, NO2, or NO, may be added to the etching chamber at a flow rate of 1 sccm to 10,000 sccm to control polymerization during the etching step.

[0090] The disclosed method can improve the etch selectivity of dielectric materials such as SiO by 20% or more relative to aC masks, and can improve the etch selectivity of multilayer SiO / SiN ONON layers by 10% or more relative to aC masks. Additionally, benefits of the disclosed method can include improved etch profiles during HAR dielectric etches, which can reduce profile bowing under certain conditions. [Example]

[0091] The following non-limiting examples are provided to further illustrate embodiments of the present invention, however, the examples are not intended to be comprehensive or to limit the scope of the invention described herein.

[0092] The disclosed method was tested on a commercial dual CCP plasma etching tool using passivation SiH2I2 (boiling point: 150°C) for oxide hole pattern wafer etching.

[0093] Wafer Information: Exemplary pattern structures for forming oxide opening patterns on a Si substrate or wafer are shown in Figures 1A and 1B. Figure 1A shows the pattern structure before mask opening. A SiO2 layer 106 is disposed on a Si substrate 108. An aC mask layer 104 is disposed on the SiO2 layer 106. A SiON resist layer 102 is disposed on the mask layer 104. Figure 1B shows the pattern structure after mask opening, where mask openings 110 are formed in the mask layer 104. In one embodiment of the following examples, the SiON resist layer 102 was 100 nm thick, the aC mask layer 104 was 700 nm thick, the SiO2 layer 106 was 3 mm thick, and the mask openings 110 ranged from 140 nm to 160 nm.

[0094] The following etching experiments were performed on a commercially available SiO2 hole-patterned wafer, which had a 3 mm SiO2 layer on a pre-etched Si substrate, and a 641 nm aC mask on top of that (hole CD is 164 nm).

[0095] Example 1: Formation of a surface protective layer using SiH2I2 This embodiment utilizes the adsorption or physical condensation of passivation molecules to form a surface protective layer on the wafer surface prior to plasma etching. More specifically, it utilizes the adsorption or physical condensation of passivation SiH2I2 (DIS or diiodosilane) to form a thin skin layer on the wafer surface prior to plasma etching.

[0096] FIG. 3A illustrates the application of non-plasma etching using SiH2I2 in a HAR dielectric etch process. As shown, step 1 is the formation of a surface protection layer on a patterned mask layer. A SiH2I2 / Ar mixture was flowed into an etching chamber or dual-CCP plasma etching tool, and the wafer was exposed in the etching chamber for a certain period of time. No source or bias plasma was added to the etching chamber. The ESC temperature for this non-plasma etching step was set. After a predetermined time, such as 60 seconds, 120 seconds, or 180 seconds, a surface protection layer 202 was formed on the patterned mask layer 204. This may be a surface condensation layer or a surface reaction layer formed on the patterned mask layer 204. Here, a portion of the surface protection layer 202 was formed on the SiO2 layer 206 containing the mask layer pattern.

[0097] FIG. 3B illustrates the application of plasma etching using fluorocarbon etching gas C4F6 in a HAR dielectric etch process after forming a surface protection layer on the patterned mask layer. As shown, step 2 is plasma etching using fluorocarbon etching gas C4F6. In this step, an oxidizer (e.g., O2) and an inert gas (e.g., Ar) may be added to the fluorocarbon etching gas C4F6, and the ESC temperature may be the same or different from that of step 1 in the non-plasma process. In this step, a plasma source and bias plasma were added to the etching chamber and run for a predetermined time, such as, but not limited to, 60 seconds, 120 seconds, or 180 seconds. Flowing fluorocarbon etching gas C4F6 into the etching chamber etched the portion of the surface protection layer 202 directly above the SiO2 layer 206 and further etched the SiO2 layer 206 against the patterned mask layer 204, thereby forming a deep opening 210 in the SiO2 layer 206.

[0098] Here, step 1 and step 2 may be cycled or alternated as needed until the desired deep opening 210 is formed in the SiO2 layer 206. The specific duration of both steps may vary for each step in subsequent cycles. Between each step, i.e., between step 1 and step 2, and between step 2 and step 1, a purging step with an inert gas or a step of evacuating using a vacuum pump to the process pressure or the base pressure of the pump may be provided.

[0099] FIG. 3C shows an oxide opening pattern formed in a patterned structure on a Si substrate 208 by SiH2I2 non-plasma formation of a surface protection layer and C4F6 plasma etching. During this process, the formation of the surface protection layer and the etching of the SiO2 layer 206 are sequentially performed in repeated cycles, forming a surface protection layer 212 on the sidewalls of the opening 210 in the SiO2 layer 206. The formation of the surface protection layer 212 and the etching of the SiO2 layer 206 do not proceed simultaneously. The surface protection layer 212 on the sidewalls of the opening 210 in the SiO2 layer 206 grows continuously downward from the surface protection layer 202 on the patterned mask layer 204, and the processes of Step 1 and Step 2 are alternated until a deep opening 210 is formed in the surface protection layer 212, as shown in FIG. 3C. A plasma etching cleaning step can then be applied to remove the protection layers 202 and 212, as shown in FIG. 3D.

[0100] The disclosed method was tested on oxide aperture pattern wafers under varying conditions. Step 1 conditions of the non-plasma exposure process were adjusted to observe the profile (e.g., CD, bowing, etc.) and selectivity. Variables for the non-plasma exposure process, including ESC temperature, chamber pressure, and exposure time, and oxide aperture pattern characteristics, are shown in Tables 3 and 4, respectively. Step 1 conditions of the non-plasma exposure process, adjusted to decouple the ESCs for Steps 1 and 2, are shown in Tables 5 and 6. Between Steps 1 and 2, the chamber was evacuated with a vacuum pump.

[0101] [Table 5]

[0102] [Table 6]

[0103] [Table 7]

[0104] [Table 8]

[0105] In the disclosed method, the chemical dosage in the non-plasma etching step can be controlled by the chamber pressure and exposure time. That is, the chamber pressure can range from 20 mTorr to 400 Torr, and the exposure time for the non-plasma etching step can be less than 120 seconds. Excessive dosage can cause necking at the top of the mask hole (i.e., 110 in Figure 1B). The ESC temperature window for the non-plasma etching step can be below the boiling point of SiH2I2 and is preferably the same as that of the plasma step (step 2). The ESC temperature window for the plasma step can be room temperature or 20°C, and a wider range can be possible with improved ESC temperature control capabilities. The disclosed method improves the etch profile and mask selectivity.

[0106] An example of selected conditions for the non-plasma / plasma step is shown in Table 7. The cycling results for the non-plasma / plasma step are shown in Table 8.

[0107] [Table 9]

[0108] [Table 10]

[0109] Example 2. Comparison between SiH2I2 and CHF3 in a non-plasma step CHF3 (boiling point -82.1 °C) was tested under the same conditions (five cycles, each lasting 60 seconds, as shown in Table 8) as a control sample for SiH2I2 and as a reference for the prior art U.S. Patent Application Publication No. 20210020450A1. In these tests, the ESC temperature was set to 20 °C. Unlike SiH2I2, no improvement in etch selectivity to aC mask was observed when wafer samples were exposed to CHF3 flowed into the etching chamber (150 sccm, 200 mtorr, 60 seconds) before being introduced into the plasma etching step. Due to the properties of CHF3, when the ESC temperature is set to 20 °C, CHF3 molecules may not adhere to the wafer sample surface and form a surface reaction or surface protection layer. Therefore, it is believed that the disclosed method may not work for low-boiling-point molecules (i.e., molecules with boiling points below 20 °C). More specifically, the disclosed method may only be effective if the boiling point of the etching gas used in the non-plasma etching step is higher than the processing temperature in the non-plasma step, as shown in FIG. 3A.

[0110] As a direct comparison between SiH2I2 and CHF3, Table 9 shows data for a non-plasma cyclic etch step performed with CHF3 at an ESC temperature of 20°C. As can be seen from this direct comparison when using SiH2I2 in the non-plasma cyclic etch step, the selectivity increases from 5.7 (baseline continuous etch process without SiH2I2) to 7.3 (non-plasma cyclic etch). When CHF3 is used in the non-plasma cyclic etch step, the selectivity remains essentially unchanged compared to the baseline continuous etch process (6.8 vs. 7.0, respectively).

[0111] [Table 11]

[0112] Although the subject matter described herein may be described in the context of example implementations for processing one or more computing application functions / operations for a computing application having a user-interactive component, the subject matter is not limited to these particular embodiments. Rather, the techniques described herein may be applied to any suitable type of user-interactive component execution management method, system, platform, and / or device.

[0113] It will be understood that many additional changes in the details, materials, steps, and arrangements of parts described and illustrated herein to illustrate the nature of the invention may be made by those skilled in the art within the principles and scope of the invention as set forth in the appended claims. Accordingly, it is not intended that the invention be limited to the specific embodiments in the examples given above and / or in the accompanying drawings.

[0114] While embodiments of the present invention have been shown and described, modifications can be made by those skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are merely exemplary and not limiting. Many variations and modifications of the compositions and methods are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is limited only by the scope of the claims, including all equivalents of the subject matter of the claims.

Claims

1. 1. A method of forming an aperture pattern in a substrate, the substrate including a film disposed thereon and a patterned mask layer disposed on the film, the method comprising: 1) exposing the substrate to a vapor of passivation molecules under a non-plasma condition for a certain period of time to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated etching gas and plasma dry etching the substrate with the plasma-activated etching gas to form openings on the patterned mask layer of the film; and 3) repeating steps 1) and 2) until a desired opening pattern is formed in the film; Including, The method, wherein the surface protection layer is also formed on the sidewalls of the opening formed in the membrane.

2. The method of claim 1 , wherein the vaporization temperature of the passivation molecules is higher than the processing temperature in step 1).

3. 3. The method of claim 2, wherein the processing temperature in step 1) is the same as the processing temperature in step 2).

4. 3. The method of claim 2, wherein the treatment temperature in step 1) is in the range of -150°C to 100°C.

5. 4. The method of claim 3, wherein the treatment temperature in step 2) is in the range of -150°C to 50°C.

6. 4. The method of claim 3, wherein the processing temperature in step 2) is 20°C.

7. The method according to any one of claims 1 to 3, wherein the passivation molecules have a boiling point of 20°C or higher.

8. 4. The method of claim 1, wherein the passivation molecules are selected from the group consisting of halogen-containing silanes, hydrofluorocarbons, I-containing hydrofluorocarbons, N-containing hydrofluorocarbons, and S-containing hydrofluorocarbons.

9. The passivation molecule is SiH ２ I ２ The method according to any one of claims 1 to 3, wherein

10. The passivation molecules are Ar, N ２ 4. The method of claim 1, wherein the fluorine-containing gas is mixed with an inert gas selected from the group consisting of Xe, Kr, Ne, and combinations thereof.

11. The etching gas has the formula: ｘ H ｙ F ｚ 4. The method of claim 1, wherein (x=1 to 6, y=0 to 3, z=1 to 10).

12. The etching gas is CF ４ , C ２ F ４ , C ２ F ６ , C ３ F ８ , C ３ F ６ , C ４ F ６ , C ４ F ８ , C ４ F １０ , C ５ F ８ , or C ６ F ６ C selected from １ ~C ６ Fluorocarbon gas or CH ３ F, CH ２ F ２ , CHF ３ , C ２ H ５ F, C ３ H ７ F, C ４ H ２ F ６ , C ３ H ２ F ６ , or C ２ HF ５ C selected from １ ~C ６ The method according to any one of claims 1 to 3, wherein the gas is a hydrofluorocarbon gas.

13. The method according to any one of claims 1 to 3, wherein the processing pressure in step 1) is in the range of 0.001 torr to 50 torr.

14. The method according to any one of claims 1 to 3, wherein the time in step 1) varies from 0.01 seconds to 10000 seconds.

15. The method according to any one of claims 1 to 3, wherein the plasma treatment time in step 2) varies from 0.01 seconds to 10000 seconds.

16. The film is SiO ２ , SiN, SiC, SiCN, or SiON layers, or alternating SiO / SiN or SiO / p-Si layers.

17. The plasma-activated etching gas contains O ２ , CO, CO ２ , NO, NO ２ , N ２ 4. The method of claim 1, further comprising adding an oxidizing agent selected from O, wherein the oxidizing agent is activated with plasma.

18. 1. A method of forming an opening pattern in a substrate, the substrate including a film disposed thereon and a patterned mask layer disposed on an oxide layer, the method comprising: 1) exposing the substrate to a gas of passivation molecules under a non-plasma condition for a certain period of time to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated etching gas and plasma dry etching the substrate with the plasma-activated etching gas to form openings on the patterned mask layer of the oxide layer; and 3) repeating steps 1) through 2) until a desired oxide opening pattern is formed in the oxide layer; wherein the surface protection layer is also formed on sidewalls of the opening in the oxide layer.

19. 20. The method of claim 18, wherein the vaporization temperature of the passivation molecules is higher than the processing temperature in step 1).

20. 1. A method of forming an aperture pattern in a substrate, the substrate including a film disposed thereon and a patterned mask layer disposed on the film, the method comprising: 1) SiH under non-plasma conditions ２ I ２ exposing the substrate to a vapor for a period of time to form a surface protective layer on the patterned mask layer; 2) exposing the substrate to a plasma activated fluorocarbon or hydrofluorocarbon etching gas and plasma dry etching the substrate with the plasma activated fluorocarbon or hydrofluorocarbon etching gas to form openings in the patterned mask layer of the film; and 3) repeating steps 1) and 2) until a desired opening pattern is formed in the film; wherein the surface protection layer is also formed on the sidewalls of the opening in the membrane.

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