Cryogenic etching using carbon oxy halides

Abstract

A cryogenic etching method for forming a hole includes mounting a substrate in a reaction chamber; cooling the substrate to a temperature below 25°C; introducing an etching gas having the following general formulas into the reaction chamber: Y3-CO-X, Y-(C=O)-X, R1-CO-X, R′-CO-R″, R′-(C=O)-O-(C=O)-R″, and COF-CxFyHz-COF, wherein X and Y are each halogens selected from F, Cl, Br, and I, R1 is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, R′ and R″ are each a fluorocarbon, hydrofluorocarbon, bromine, hydrobromocarbon, chlorine, hydrochloric, or hydrocarbon, iodine, or hydroiodine, and x, y, and z are integers; converting the etching gas into a plasma; and allowing an etching reaction to occur between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the hole.

Description

[Technical Field]

[0001] This invention relates to a method for low-temperature plasma etching of silicon-containing materials using carbon oxyhalide etching gases to manufacture semiconductor wafers (such as 3D NAND flash memory and DRAM wafer manufacturing). [Previous Technology]

[0002] Carbon oxyhalides have been used as etching gases; for example, difluoropropylene fluoride (C3O2F4, CAS # 5930-67-6) and trifluoroacetyl fluoride (C2F4O, CAS No.: 354-34-7) are known etchants in plasma and thermal etching, as shown in the prior art below. Furthermore, carbon oxyhalides are known for their reactivity with water at room temperature.

[0003] WO 2023157441 and WO 2023157442 disclose an etching method in which the etching compound may have fluorine and oxygen atoms in the molecule, but not hydrogen atoms, including carbofluorine (COF2), oxygen difluoride (OF2), and trifluoromethyl hypofluoride (CF3OF). However, none of the examples use etching compounds having fluorine and oxygen atoms.

[0004] US 20220115240 discloses a dry etching method in which the dry etchant comprises CF3I, a fluorinated linear nitrile compound having 2 or 3 carbon atoms, and an additive gas including CF3OF.

[0005] US 20050014383 discloses a mixture for etching dielectric materials in layered substrates, the mixture comprising a fluorinated hydrocarbon and a fluorinated oxidant having the formula CxHyFz(OF)nOm, wherein x is a number ranging from 0 to 8, y is a number ranging from 0 to 17, z is a number ranging from 0 to 17, n is 1 or 2, and m is 0, 1, or 2.

[0006] WO 2012114611 discloses a clean gas comprising a mixture of: a compound represented by CFxOy (where x is 2 or 4, and y is an integer from 1 to 3 when x = 2 or from 1 to 4 when x = 4), and N2. Compared to conventional clean gases using NF3, this clean gas achieves a lower global warming coefficient and a faster etching rate.

[0007] JP 2000265275 A2 discloses the use of plasma-activated CF3COF to clean unwanted deposits on equipment used for thin film production. The process temperature is at room temperature or higher. There are no particular limitations on the temperature inside the reactor during cleaning, as the method can achieve sufficiently high rates even at room temperature; however, if the temperature is too high, equipment materials such as metals and resins can be damaged. Preferably, the temperature of metal parts is controlled to 700°C or lower and the temperature of resin materials is controlled to 100°C or lower. The addition of etchants such as HF is not disclosed.

[0008] US 6242359 B1 discloses a plasma cleaning and etching method using non-global warming plasma etching and cleaning chambers. This method utilizes gases such as perfluoropropane dialdehyde (CFOCF2CFO) (which is C3O2F4), pentafluoropropanefluorine (CF3CF2CFO), trifluoroacetylfluorine (CF3CFO), acetylfluorine (CH3CFO), oxalofluorine ((COF)2), and 1,1,1-trifluoroacetone (CF3COCH3)CF3COF. The substrate temperature is not specified. The etching method is used to etch silicon-containing dielectric and metal layers from the chamber walls or from a silicon wafer substrate. Furthermore, oxygen-containing gases can be added to improve etching selectivity and enhance the formation of active materials. Suitable oxygen-containing gases include, for example, oxygen, ozone, nitrous oxide, and nitric oxide. The addition of etchants such as HF is not disclosed.

[0009] US 6821454 B2 discloses a method for removing water from a surface using a fluorinated nonionic additive component A) having the following formula: T-ORf(CFY)-L (per)fluorinated polyether component B), wherein the weight ratio (K) between the (per)fluorinated portion and the hydrogenated L portion of the additive is in the range of 1.50-4.00, and the ratio KI between the number average molecular weight of the fluorinated polyether portion T-ORf- of the additive and the number average molecular weight of component B) is greater than 1.60, but does not disclose the temperature and does not specifically disclose CF3COF.

[0010] US 20230197465 A1 discloses an oxygen- and iodine-containing hydrofluorocarbon compound for etching semiconductor structures at low temperatures (ranging from approximately -196°C to approximately 500°C), the hydrofluorocarbon compound having the formula CnHxFyIzOe, where 0 ≤ n ≤ 10, 0 ≤ x ≤ 21, 0 ≤ y ≤ 21, 1 ≤ z ≤ 4 and 1 ≤ e ≤ 2; it does not disclose an oxygen-fluorine molecule (such as CF3COF), and the molecule must contain iodine.

[0011] Yoji Saito et al. (J. Vac. Sci. Technol. A [Journal of Vacuum Science and Technology, A] 19, 38-40 (2001)) disclosed a distal plasma-enhanced reaction between a silicon surface and a trifluoroacetyl fluoride gas, in which distal plasma was used to demonstrate the etching reaction between silicon and the trifluoroacetyl fluoride gas at room temperature. CF3COF is adequately reactive with water and decomposes into trifluoroacetic acid and hydrogen fluoride. The substrate temperature was room temperature during the etching experiments. O2 was added to enhance the etching reaction. The etching rate of the silicon dioxide film showed a similar trend to that of Si with O2 content, but its value was about one-tenth that of etching silicon. Therefore, their results show that CF3COF is not a good plasma etchant for etching SiO2, which is selective for materials like Si, which can be a mask material.

[0012] US 11183393 B2 discloses atomic layer etching of silicon oxide or silicon nitride films using acetal halides. Atomic layer etching (ALE) is performed by repeating the following three steps: (i) a hydrogenation step, in which the surface is hydrogenated by irradiating it with a plasma containing H; (ii) a chlorohydrin adsorption step, in which the chlorohydrin reacts with the hydrogenated surface by exposing it to a chlorohydrin represented by the formula Rf-COX (Rf being H, F, a substituent composed of C and F or C, H and F, or -COX; each X being independently any halogen atom of F, Cl, Br and I); and (iii) an etching step, in which a single atomic layer is etched by irradiating the surface with a plasma containing at least one rare gas (He, Ar, Ne, Kr and Xe) to induce a chemical reaction on the surface of the silicon oxide or silicon nitride film with the chlorohydrin adsorption. CF3COF was disclosed as the etchant. The Rf-COX used in step (ii) is any one of COF2, COFH, COFCl, COFBr, COFI, CF3COF, CHF2COF, CF3COCl, CHF2COCl, (COF)2, and (COF)COCl. The only statement regarding temperature refers to the reaction between the surface of the hydrogen-capped etched target and the acetal halide at standard temperatures. It should be noted that the use of plasma is limited to steps 1 and 3; plasma is not used during the acetal halide adsorption step. The addition of etchants such as HF is not disclosed.

[0013] US 9623590 B2 discloses a micro-textured structure product, a thermally reactive resist material for dry etching, a mold manufacturing method, and a mold. Examples of sidewall protection gases are fluorinated gases, such as CHF3, CH2F2, C2F6, C3F8, C4F6, C4F8, C4F10, C5F10, CCl2F2, CF3I, CFBr, CHF2COF, and CF3COF. These fluorinated gases can be used alone as sidewall protection gases, or mixed gases obtained by mixing these gases can be used as sidewall protection gases. For example, fluorinated gases (sidewall protection gases) can be used for dry etching using RIE (reactive ion etching), ECR (electron cyclotron resonance) plasma etching, and microwave etching. In addition, mixed gases obtained by mixing fluorine-containing gases as described above with gases such as O2, H2, Ar, N2, CO, HBr, NF3, HCl, HI, BBr3, BCl3, Cl2, and SiCl4 can also be used as sidewall protection gases, provided that the gas can achieve a sidewall protection effect during dry etching. It should be noted that mixing with HF is not disclosed.

[0014] US 6787053 B2 discloses cleaning and etching gases, wherein the first chamber cleaning gas and the first silicon-film-containing etching gas of the invention contain specific amounts of at least one compound selected from the group consisting of FCOF, CF3OCOF, and CF3OCF2OCOF, and O2, and other gases as needed. The second chamber cleaning gas and the second silicon-film-containing etching gas contain specific amounts of CF3COF, C3F7COF, or CF2(COF)2 (i.e., C3O2F4) and O2, and may contain other gases as needed. The chamber cleaning gas and the silicon-film-containing etching gas of the invention have low global warming potential values ​​and produce almost no environmentally harmful substances such as CF4 that are already considered to contribute to global warming in the exhaust gas. Therefore, these gases are environmentally friendly and have easy handling and excellent exhaust treatment characteristics. In addition, the chamber cleaning gas of the invention has an excellent cleaning rate. The other gases mentioned above may include gases other than the above-mentioned inert gases to a limit that does not impair the purpose of the invention. Examples of gases other than inert gases may include O3, H2, F2, ClF3, or BrF3. The only temperature in the disclosed plasma process is 300°C. They noted that CF3COF, C3F7COF, and CF2(COF)2 used in the invention readily react with moisture to decompose into HF and CF3COOH. For this reason, even though CF3COF, C3F7COF, and CF2(COF)2 are discharged as undecomposed exhaust gas after chamber cleaning, they can be readily decomposed into HF and CF3COOH by a water scrubber in a conventional exhaust treatment system. However, this describes a reaction concerning water post-treatment rather than as part of the etching process itself.

[0015] WO 2023243569 A1 discloses an etching method, an etching method for producing semiconductor devices, etching equipment, and etching gas, wherein the process temperature is preferably 20°C or higher and 200°C or lower, more preferably 30°C or higher and 150°C or lower, and 40°C or higher, or 130°C or lower. The etching method is used to etch films containing at least Si and O and films containing at least Si and N in a substrate by contacting (i) HF gas and (ii) at least one compound selected from the group consisting of sulfonyl compounds, carbonyl compounds, sulfonyl isocyanate compounds, and isocyanate compounds with the substrate. The carbonyl compound is represented by the following formula: R2-C(=O)-R3, where R2 and R3 each independently represent a straight-chain or branched alkyl group having 1 to 6 carbon atoms, some or all of which may be substituted with fluorine atoms, hydrogen atoms, halogen atoms, or isocyanate groups. Specifically, the carbonyl compounds represented by the above general formula are hexafluoroacetone (CF3C(=O)CF3), trifluoroacetaldehyde (CF3C(=O)H), or fluorocarbonyl isocyanate (FC(=O)N=C=O). The etching method described is preferably used to etch films containing Si and N without involving a plasma state.

[0016] US 5626775 A discloses plasma etching using trifluoroacetic acid and its derivatives for etching SiO2 and SiN, as well as other materials, under plasma conditions to clean and remove SiO2 and SiN from the walls and other surfaces within a reaction chamber (such as a PECVD reactor). Process temperatures are specified as 25°C to 500°C. The addition of other gases, such as oxygen and inert gases, is disclosed. The addition of etchants such as HF is not disclosed.

[0017] WO 2019002058 discloses an etching method and a plasma etching material, trifluoroacetic anhydride, in plasma etching. Etching is performed using C4F6O3 at temperatures ranging from -20°C to 200°C. The addition of other fluorocarbons is described, including CF4, CF3I, C2F3I, C3F5I, C3F7I, C2F6, C3F6, C3F8, C4F8, C4F6, C5F8, C6F6, CH3F, CHF3, CH2F2, C2HF5, C3HF5, C3H2F4, C3H2F6, C4HF7, and C4H2F6. The addition of other oxidizing gases is described, including O2, O3, CO, CO2, NO, N2O, NOF, SO2, and COS. The addition of etchants such as HF is not disclosed.

[0018] US 20030216041 discloses in-situ hot chamber cleaning. The chemicals include one or more etching gases selected from the group consisting of: NF3, CF4, C2F6, C3F8, F2, ClF3, (CF3CO)2O, C4F8O, C4F8, anhydrous HF, CHF3, and mixtures thereof. Preferably, the first cleaning process is performed at a temperature ranging from about 500°C to 800°C and a pressure ranging from about 100 Torr to 700 Torr. The second cleaning process is preferably performed at a temperature ranging from about 500°C to 800°C and a pressure ranging from about 5 Torr to 100 Torr. The disclosed method does not involve the use of plasma.

[0019] Pruette et al. ("evaluation of trifluoroacetic anhydride as an alternative plasma enhanced chemical vapor deposition chamber clean chemistry", J. Vac. Sci. Technol. A) 16, 1577-1581 (1998) disclosed the chamber clean time and emissions when using one such substance (trifluoroacetic anhydride (TFAA)).

[0020] Karecki et al. ("Plasma Etching of Silicon Dioxide and Silicon Nitride with Non-Perfluorocompound Chemistries: Trifluoroacetic Anhydride and Iodofluorocarbons", MRS Online Proceedings Library, 447, 67-74 (1996)) disclosed the etching of SiO2 and SiN using trifluoroacetic anhydride (TFAA) via a magnetically enhanced reactive ion etching tool. The reaction temperature was not mentioned.

[0021] Karecki (Development of novel alternative chemistry processes for dielectric etch applications) by Karecki and Simon Martin (2000) discloses an evaluation of fluorinated compounds belonging to three main families of modified fluorocarbon molecules: hydrofluorocarbons (HFCs), iodofluorocarbons (IFCs), and unsaturated fluorocarbons (UFCs). In addition, other chemicals, namely trifluoroacetic anhydride (TFAA), oxalofluorocarbons, and octafluorotetrahydrofuran, are also disclosed.

[0022] US 20240112922 A1 discloses an etching method comprising (a) preparing a substrate including a silicon-containing film and a mask, the silicon-containing film including recesses, the mask disposed on the silicon-containing film and including openings exposing the recesses; (b) forming a carbon-containing film on a sidewall of the silicon-containing film, the sidewall defining the recesses; and (c) forming a tungsten-containing protective film on the carbon-containing film and etching the silicon-containing film in the recesses by using a plasma generated by a process gas comprising a fluorine-containing gas and a tungsten-containing gas. The temperature is as low as -80°C. The silicon-containing film is etched in step (c). The fluorine-containing gas included in step (c) may be, for example, hydrogen fluoride gas (HF gas) and / or hydrofluorocarbon gas. The tungsten-containing gas included in step (c) may be, for example, a gas containing tungsten and a halogen, such as WF6. Step (c) may further include a phosphorus-containing gas, such as PF3. Step (c) may further include a carbon-containing gas. The carbon-containing gas may be, for example, any or both of fluorocarbon and hydrofluorocarbon gases. The carbon-containing gas may include C4F8O (pentafluoroethyl trifluorovinyl ether) gas, CF3COF gas (1,2,2,2-tetrafluoroethane-1-one) gas, CHF2COF (difluoroacetic acid fluoride) gas, and COF2 (carbonyl fluoride) gas, along with a long list of gases including CF4, C4F6, C4F8, and C5F8, and hydrofluorocarbon gases including CHF3, CH2F2, and CH3F, etc. No data or explanation is given regarding the inclusion of CF3COF, CHF2COF, and COF2.

[0023] US 20240153744 A1 discloses an etching method for forming a recess by etching a target film, wherein a source power and a bias power are applied cyclically, wherein the film is etched in a first cycle, and a second process gas is adsorbed onto the etched target film in a second cycle, wherein only one of the source or bias power is applied. The substrate may include a silicon nitride film, and the second process gas may contain an acid component. The second process gas may contain an acid component, and in the second cycle, after the second process gas is adsorbed onto the etched target film, a third process gas containing an alkaline component may be supplied to the chamber. In this case, the acid component is adsorbed onto the etched target film, and thereafter, the acid component and the alkaline component react with each other to form a salt. The acid component may include at least one selected from the group consisting of: formic acid, acetic acid, HCl, HBr, HI, trichloroacetic acid, and citric acid. In the etching method, the first process gas may include a phosphorus-containing gas and a fluorine-containing gas. The first process gas may include HF gas or an HF-generating gas (such as hydrofluorocarbon gas). The phosphorus-containing gas may be PF3. The first process gas may include a carbon-containing gas. This carbon-containing gas may be at least one or both of fluorocarbon or hydrofluorocarbon gases, which may include C4F8O (pentafluoroethyl trifluorovinyl ether), CF3COF (1,2,2,2-tetrafluoroethane-1-one), CHF2COF (difluoroacetic acid fluoride), and COF2 (fluorinated carbonyl). The first process gas may also include a metal-containing gas (such as a tungsten-containing gas like WF6), an oxygen-containing gas, a halogen-containing gas, and a rare gas (such as Ar). The temperature of the undisclosed substrate is also considered.

[0024] Therefore, there is a need to explore new etchant chemicals for low-temperature etching / cryogenic etching in the semiconductor industry to enhance the etching rate and help dehydrate the surface of excess H2O generated during the etching process. [Summary of the Invention]

[0025] An etching method is disclosed for selectively etching one or more silicon-containing films from a substrate to form holes by using a patterned mask layer deposited on top of one or more silicon-containing films. The method includes the following steps: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below 25°C; introducing an etching gas having the following general formula into the reaction chamber: Y3-CO-X, Y-(C=O)-X, R1-CO-X, R2-CO-R3, R2-(C=O)-O-(C=O)-R3, and COF-CxFyHz-COF, wherein X and Y are each halogens selected from F, Cl, Br, I, R1 is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, R2 and R3 are each a fluorocarbon, hydrofluorocarbon, bromine, hydrobromocarbon, chlorine, hydrochlorocarbon, or hydrocarbon, iodocarbon, hydroiodocarbon, and x, y, and z are integers. The etching gas is converted into a plasma; and an etching reaction is allowed between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the aperture. The disclosed etching method may include one or more of the following features: ● Further comprising adding one or more hydrofluorocarbon or fluorocarbon etching gases to the etching gas, wherein the one or more hydrofluorocarbon or fluorocarbon etching gases are selected from C4F6, C4F8, C4H2F6, CHF3, CH2F2, CH3F, CF4, C2F6, C3F8, SF6, NF3, C2F4, C3F6, C4F10, C5F8, C6F6, C1-C6CxFyHz molecules (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combinations thereof; ● Further, this includes adding a co-reactant to the etching gas, wherein the co-reactant is selected from H2, SF6, NF3, N2, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, HF, B2H6, and P-containing gases such as PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, P(R)3 (where R is an alkyl or fluorinated alkyl group), SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, or CF4SO2; ● The co-reactant is a sulfur-containing gas; ● The sulfur-containing gas has the general formula SOmXn and R-SOmXn, where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon; ● The sulfur-containing gas system contains SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, and CF4SO2; ● The co-reactant system contains P gas;● The P-containing gas system includes PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, and P(R)3, wherein R is an alkyl or fluorinated alkyl group; ● P(R)3 is P(CF3); ● Further includes adding a co-reactant to the etching gas, wherein the co-reactant is selected from O2, CO, CO2, NO, NO2, N2O, SO2, H2S, COS, O3, CxOyFz (x, y, and z are integers), and CxOyFzHm (x, y, z, and m are integers) selected from alcohols, ketones, acids, and esters; ● Further includes adding the co-reactant O2 to the etching gas; ● Further includes adding a co-reactant to the etching gas, wherein the co-reactant is an inert gas selected from Ar, Kr, Xe, Ne, N2, He, or combinations thereof added to the etching gas; ● The etching gas system is a carbon oxyhalide; ● These carbon oxyhalides have lower GWPs compared to commonly used substances (e.g., CF4, C4F8, CH2F2); ● The etching gas system is an amide halogen; ● These carbon oxyhalides are Y3-CO-X or Y-(C=O)-X, wherein X and Y are each halogens selected from F, Cl, Br, and I; ● The etching gas system is CF3OF; ● The etching gas system is COF2; ● These carbon oxyhalides are the main family of amide halides, R1-CO-X, wherein X is a halide such as F, Cl, Br, or I, and R1 is a fluorocarbon, hydrofluorocarbon, or hydrocarbon; ● The etching gas system is C3O2F4; ● The etching gas system is CF3COF; ● The etching gas system is C2O2F2; ● The etching gas system is C3O2F4 and its isomers; ● The etching gas system is CF3COF and its isomers; ● The etching gas system is COF2 and its isomers; ● The etching gas system is C2O2F2 and its isomers; ● These carbon oxyhalides are the main family of acetylated halides, R2-CO-R3, wherein R2 and R3 are fluorocarbons, hydrofluorocarbons, bromines, hydrobromocarbons, chlorines, hydrochlorohydrocarbons or hydrocarbons, iodines, and hydroiodides; ● These carbon oxyhalides are CF3-CO-CF3; ● These carbon oxyhalides are CH3-CO-CH3; ● These carbon oxyhalides are the main family of acetylated halides, R2-(C=O)-O-(C=O)-R3, wherein R2 and R3 are fluorocarbons, hydrofluorocarbons, bromines, hydrobromohydrocarbons, chlorines, hydrochlorohydrocarbons or hydrocarbons, iodines, and hydroiodides; ● These carbon oxyhalides are CF3-CO-CF3; ● These carbon oxyhalides are CH3-CO-CH3; ● The main family of acetylated halides, such as COF-CxFyHz-COF, where x, y, and z are integers; ● The carbon oxyhalide system, such as (COF)-CF2-(COF);● These carbon oxyhalides include C3O2F4 (CAS No.: 5930-67-6), CF3OF (CAS No.: 373-91-1), CF3COF (CAS No.: 354-34-7), C3F6O (CAS No.: 422-61-7), C2F3OI (CAS No.: 354-36-9), C2F3OCl (CAS No.: 354-32-5), C2O2F2 (CAS No.: 359-40-0), and C4F6O3 (TFAA). CAS No.: 407-25-0), C4H3F3O (CAS No.: 162880-35-5), C3H3F3O (CAS No.: 2255428-10-3), C2HF3O (CAS No.: 2925-22-6), C2HF3O (CAS No.: 75-90-1), C3HF5O (CAS No.: 663-74-1), C3HF5O (CAS No.: 6065-84-5), C3HF5O (CAS No.: 85592-82) -1), C2HClF2O (CAS No.: 381-72-6), C2HF3O (CAS No.: 814-77-7), C2HClFIO (CAS No.: 955374-72-8), C4HF5O3 (CAS No.: 406727-03-5), C4H2F4O3 (CAS No.: 401-67-2), C4H2F4O3 (CAS No.: 406727-04-6), C4H4F2O3 (CAS No.: 407-33-0 C4H3F3O3 (CAS No.: 1784758-59-3), C4H4F2O3 (CAS No.: 406727-05-7), C4H3F3O3 (CAS No.: 96-63-9), C2HClF2O (CAS No.: 811-96-1), C2HBrF2O (CAS No.: 353-79-7), C2HF2IO (CAS No.: 1334483-62-3), or C3F6O (CAS No.: 684-16-2); ● The substrate temperature is below approximately 0°C; ● The substrate temperature range is approximately -196°C to approximately 300°C; ● The substrate temperature range is approximately -196°C to approximately 60°C; ● The substrate temperature range is approximately -196°C to approximately 0°C; ● The aspect ratio of the via ranges from 1:1 to 5:1; ● The aspect ratio of the via is greater than 5:1; ● The aspect ratio of the via is greater than 20:1; ● The aspect ratio of the via ranges from approximately 5:1 to approximately 500:1; ● The via has a diameter ranging from approximately 0.1 nm to approximately 500 nm; ● The via has a diameter less than 100 nm; ● After forming the via, the substrate temperature is raised to greater than 0°C;● These carbon oxide halide etching gases have a low moisture content of <40 ppm; and;

[0026] These carbon oxide halide etching gases have a low moisture content of <10 ppm.

[0027] A low-temperature etching method is disclosed for selectively etching one or more silicon-containing films from a substrate to form a hole by using a patterned mask layer deposited on top of one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below about 25°C; introducing an etching gas CF3OF, CF3COF, C3O2F4, C2O2F2, or COF2 into the reaction chamber; converting the etching gas into a plasma; and allowing an etching reaction to occur between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the hole. The disclosed etching method may include one or more of the following features: ● Further includes adding one or more hydrofluorocarbon or fluorocarbon etching gases to the etching gas, wherein the one or more hydrofluorocarbon or fluorocarbon etching gases are selected from C4F6, C4F8, C4H2F6, CHF3, CH2F2, CH3F, CF4, C2F6, C3F8, SF6, NF3, C2F4, C3F6, C4F10, C5F8, C6F6, C1-C6CxFyHz molecules (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combinations thereof; ● Further, this includes adding a co-reactant to the etching gas, wherein the co-reactant is selected from H2, SF6, NF3, N2, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, HF, B2H6, and P-containing gases such as PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, P(R)3 (where R is an alkyl or fluorinated alkyl group), SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, or CF4SO2; ● The co-reactant is a sulfur-containing gas; ● The sulfur-containing gas has the general formula SOmXn and R-SOmXn, where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon; ● The sulfur-containing gas system includes SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, and CF4SO2; ● The co-reactant system contains P gas; ● The P-containing gas system includes PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, and P(R)3, where R is an alkyl or fluorinated alkyl group; ● P(R)3 is P(CF3);● Further includes adding a co-reactant to the etching gas, wherein the co-reactant is selected from O2, CO, CO2, NO, NO2, N2O, SO2, H2S, COS, O3, CxOyFz (x, y, and z are integers), and CxOyFzHm (x, y, z, and m are integers) selected from alcohols, ketones, acids, and esters; ● Further includes adding the co-reactant O2 to the etching gas; ● Further includes adding a co-reactant to the etching gas, wherein the co-reactant is an inert gas selected from Ar, Kr, Xe, Ne, N2, He, or combinations thereof added to the etching gas; ● The substrate temperature is below approximately 0°C; ● The substrate temperature range is approximately -196°C to approximately 300°C; ● The substrate temperature range is approximately -196°C to approximately 60°C; ● The substrate temperature range is approximately -196°C to approximately 0°C; ● The aspect ratio of the aperture ranges from 1:1 to 5. : 1; ● The aspect ratio of the aperture is greater than 5:1; ● The aspect ratio of the aperture is greater than 20:1; ● The aspect ratio of the aperture ranges from approximately 5:1 to approximately 500:1; ● The aperture has a diameter ranging from approximately 0.1 nm to approximately 500 nm; ● The aperture has a diameter less than 100 nm; ● After forming the aperture, the temperature of the substrate is raised to greater than 0°C; ● The etching gas CF3OF, CF3COF, C3O2F4, C2O2F2, or COF2 has a low moisture content of <40 ppm; and ● The etching gas CF3OF, CF3COF, C3O2F4, C2O2F2, or COF2 has a low moisture content of <10 ppm.

[0028] A low-temperature etching method is disclosed for selectively etching one or more silicon-containing films from a substrate to form a hole by using a patterned mask layer deposited on top of one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below about 25°C; introducing an etching gas CF3OF, CF3COF, C3O2F4, C2O2F2, or COF2 into the reaction chamber; adding a co-reactant O2 to the reaction chamber to convert the etching gas into a plasma; and allowing an etching reaction to occur between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the hole. The disclosed etching method may include one or more of the following features: ● Further includes adding one or more hydrofluorocarbon or fluorocarbon etching gases to the etching gas, wherein the one or more hydrofluorocarbon or fluorocarbon etching gases are selected from C4F6, C4F8, C4H2F6, CHF3, CH2F2, CH3F, CF4, C2F6, C3F8, SF6, NF3, C2F4, C3F6, C4F10, C5F8, C6F6, C1-C6CxFyHz molecules (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combinations thereof; ● Further, this includes adding a co-reactant to the etching gas, wherein the co-reactant is selected from H2, SF6, NF3, N2, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, HF, B2H6, and P-containing gases such as PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, P(R)3 (where R is an alkyl or fluorinated alkyl group), SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, or CF4SO2; ● The co-reactant is a sulfur-containing gas; ● The sulfur-containing gas has the general formula SOmXn and R-SOmXn, where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon; ● The sulfur-containing gas system includes SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, and CF4SO2; ● The co-reactant system contains P gas; ● The P-containing gas system includes PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, and P(R)3, where R is an alkyl or fluorinated alkyl group; ● P(R)3 is P(CF3);● Further includes adding a co-reactant to the etching gas, wherein the co-reactant is an inert gas selected from Ar, Kr, Xe, Ne, N2, He, or combinations thereof added to the etching gas; ● The substrate temperature is below approximately 0°C; ● The substrate temperature range is approximately -196°C to approximately 300°C; ● The substrate temperature range is approximately -196°C to approximately 60°C; ● The substrate temperature range is approximately -196°C to approximately 0°C; ● The aspect ratio of the via ranges from 1:1 to 5:1; ● The aspect ratio of the via is greater than 5:1; ● The aspect ratio of the via is greater than 20:1; ● The aspect ratio of the via ranges from approximately 5:1 to approximately 500:1; ● The via has a diameter ranging from approximately 0.1 nm to approximately 500 nm; ● The via has a diameter less than 100 nm; ● After forming the via, the substrate temperature is raised to greater than 0°C; ● The etching gas CF3OF, CF3COF, C3O2F4, C2O2F2, or COF2 has a low moisture content of <40 ppm; and ● the etching gas CF3OF, CF3COF, C3O2F4, C2O2F2, or COF2 has a low moisture content of <10 ppm. Symbols and nomenclature;

[0029] The following detailed description and claims utilize many abbreviations, symbols and terms commonly known in the art, and include:

[0030] As used herein, the indefinite article “a / an” means one or more species.

[0031] As used herein, “about” or “around / approximately” in the text or request means ±10% of the value.

[0032] As used herein, “room temperature” in the text or request means approximately 20°C to approximately 25°C.

[0033] The term "substrate" refers to one or more materials on which a process is performed. A substrate can refer to a wafer having one or more materials on which a process is performed. A substrate can be any suitable wafer used in the manufacture of semiconductor, photovoltaic, flat panel, or LCD-TFT devices. A substrate can also have one or more different material layers deposited thereon from previous manufacturing steps. For example, a wafer can include silicon layers (including but not limited to crystalline, amorphous, porous, etc.), silicon-containing layers (including but not limited to SiO2, SiN, SiON, SiCOH, etc.), metal or metal-containing layers (including but not limited to copper, cobalt, ruthenium, tungsten, platinum, palladium, nickel, ruthenium, gold, etc.) or combinations thereof. Furthermore, a substrate can be planar or patterned. A substrate can be an organically patterned carbon iodide film. The substrate may include oxide layers of dielectric materials (e.g., ZrO2-based materials, HfO2-based materials, TiO2-based materials, rare earth oxide-based materials, ternary oxide-based materials, etc.) used as electrodes in field-effect transistors (FETs) such as FinFET, MOFSET, GAAFET (Gate All-Around FET), strip FET, nanosheet, fork FET, complementary FET (CFET), MEMS, 3D NAND, MIM, DRAM, or FeRam device applications, or nitride-based films (e.g., TaN, TiN, NbN). The substrate may include alternating layers of oxides (e.g., SiO) and nitrides (e.g., SiN). Those skilled in the art will recognize that the terms "film" or "layer" as used herein refer to a material of a certain thickness laid or spread on a surface, and that surface may be trenches or lines. Throughout this specification and the claims, the wafer and any associated layers thereon are referred to as the substrate. The substrate can be any solid having functional groups on its surface that tend to react with reactive heads that self-assembled monolayers (SAMs), and can include, but is not limited to, 3D objects or powders.

[0034] The term "wafer" or "patterned wafer" refers to a wafer having a stack of films on a substrate, wherein at least the topmost film of the stack of films has morphological features or patterns that have been generated in a step prior to etching, and a patterned topmost film is formed for patterned etching.

[0035] As used herein, the term “processing” includes patterning, exposure, development, etching, deposition, cleaning and / or removal of byproducts, as required when forming the described structure.

[0036] The term "etch" refers to a series of processes in which material is removed from the wafer surface or other surfaces within a process chamber. Chemical reactions are involved in the process, occurring after the generation of reactive gases by plasma or after the reactive gases are activated by heating. Physical processes are involved when a bias voltage is present in the plasma to accelerate ion bombardment of the surface and physically sputter away the substrate material. The plasma can 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 etching chambers include, but are not limited to, Lam Research's dual CCP reactive ion etching product family of dielectric etching equipment sold under the trademarks Flex™ or Tokyo Electron Tactras™ or Episode™UL. Non-plasma exposure steps can be performed in a different chamber than the plasma exposure steps.

[0037] The term "aspect ratio" refers to the ratio of the height of a groove (or hole) to the width of the groove (or the diameter of the hole).

[0038] The term "high aspect ratio (HAR)" refers to an aspect ratio ranging from about 1:1 to about 500:1, preferably from about 20:1 to about 400:1.

[0039] The term "high aspect ratio etching" refers to the formation of a hole pattern in a target film by means of plasma etching, wherein the aspect ratio of the hole structure formed exceeds 5.

[0040] It should be noted that the terms "film," "layer," and "material" are used interchangeably herein. It should be understood that a film may correspond to or be associated with a layer or a material, and a layer may refer to both a film and a material. Furthermore, those skilled in the art will recognize that, as used herein, the terms "film," "layer," or "material" refer to a material of a certain thickness laid or spread on a surface, and that surface may range from as large as an entire wafer to as small as a trench or line.

[0041] It should be noted that in this document, the terms “aperture”, “via”, “hole”, “trench”, “feature” and “structure” are used interchangeably to refer to openings formed in a semiconductor structure.

[0042] As used herein, the abbreviation "NAND" refers to a "Negative AND or Not AND" gate; the abbreviation "2D" refers to a 2D gate structure on a planar substrate; and the abbreviation "3D" refers to a 3D or vertical gate structure in which the gate structures are stacked in the vertical direction.

[0043] As used herein, the terms "etching gas" or "etching agent" refer to one or more gaseous materials used for etching. One or more material sources in a container providing the vapor for etching may contain gaseous, liquid, or solid states of said one or more materials and / or combinations thereof. The etching gas and / or etching agent may be a single gaseous material or a chemical. The etching gas and / or etching agent may be a mixture of more than one gaseous material or chemical.

[0044] It should be noted that in this document, the term "QMS" refers to quadrupole mass spectrometry or quadrupole mass spectrometer.

[0045] It should be noted that, in this document, the terms "etch gas" and "etching gas" are used interchangeably when the etching gas is in a gaseous state at room temperature and ambient pressure. It should be understood that etching gas may correspond to or be associated with etchant or etching gas, and the etchant may refer to the etching gas.

[0046] The term "doping" is used interchangeably in processes that incorporate one or more elements into a film by means of various methods that can chemically or physically combine them, and in processes that intentionally incorporate atoms of different elements into a film composition. One or more elements can be interstitially doped or alternatively doped within the film.

[0047] The term “cryogenic etch / cryo-etch / cryogenic etching / cryo-etching / low temperature etch / low temperature etching” can be used interchangeably with the etching process disclosed herein, in which the substrate is cooled to below room temperature.

[0048] The standard abbreviations of the elements in the periodic table are used in this document. It should be understood that elements may be referred to by these abbreviations (for example, Si refers to silicon, N refers to nitrogen, O refers to oxygen, C refers to carbon, H refers to hydrogen, F refers to fluorine, etc.).

[0049] A unique CAS registry number (i.e., "CAS") assigned by the Chemical Abstracts Service is provided to identify the specific molecule disclosed.

[0050] As used herein, the term "hydrofluorocarbon" refers to a saturated or unsaturated functional group containing only carbon, fluorine and hydrogen atoms.

[0051] As used herein, the term "fluorocarbon" refers to a saturated or unsaturated functional group containing only fluorine and hydrogen atoms.

[0052] As used herein, the term "hydrocarbon" refers to a saturated or unsaturated functional group containing only hydrogen and carbon atoms.

[0053] As used herein, the term “GWP” refers to global warming potential, typically measured on a 100-year timescale and compared to CO2.

[0054] As used herein, the term "GWP100" refers to a GWP that is over 100 years old.

[0055] As used herein, the terms "CO2eq" or "CO2e" refer to CO2 equivalent emissions, that is, greenhouse gas emissions equivalent to CO2 by using the mass of the emitted substance and multiplying it by the substance's GWP. This allows for equivalent comparisons of process emissions between two different etching gases using the GWP of each molecule.

[0056] As used herein, “CO2 emissions (CO2e)” or “CO2 equivalent emissions (CO2eq)” are used interchangeably to refer to emissions relative to the effects of global warming.

[0057] In this document, a range may be expressed as from about one specific value and / or about another specific value. When such a range is expressed, it should be understood that another embodiment is from that one specific value and / or to that other specific value, together with all combinations within the range. Any and all ranges listed herein include their endpoints (i.e., x = 1 to 4, or the range of x is 1 to 4, including x = 1, x = 4, and x = any number in between), regardless of whether the term "inclusive" is used.

[0058] References to "one embodiment" or "implementation" herein mean that a particular feature, structure, or characteristic described with respect to that embodiment may be included in at least one embodiment of the invention. The phrase "in one embodiment" appearing in different places in the specification does not necessarily refer to the same embodiment in all instances, and a single or alternative embodiment is not necessarily mutually exclusive with other embodiments. The above also applies to the term "implementation".

[0059] As used herein, the term "exemplary" is used to mean serving as an instance, example, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as superior to or advantageous to other aspects or designs. Rather, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0060] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise stated or clear from the context, "X adopts A or B" is intended to mean any natural inclusive arrangement. That is, if X adopts A; X adopts B; or X adopts both A and B, then "X adopts A or B" is satisfied in any of the foregoing cases. Furthermore, the article "a / an" as used in this application and the appended claims should generally be interpreted as meaning "one or more" unless otherwise stated or clearly indicated from the context to the singular form.

[0061] The term “comprising” in the request is an open transitional term, meaning that the subsequently determined elements of the request are a non-exclusive list (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” is defined herein as necessary to cover the more restrictive transitional terms “substantially constitutes” and “consistent with”; therefore, “comprising” can be replaced by “substantially constitutes” or “consistent with” and remain within the clearly defined scope of “comprising”.

[0062] The term "provide" in the claims is defined as meaning to supply, provide, make available, or prepare something. The steps can, conversely, be performed by any actor in the absence of explicit language in the claims.

Implementation Method

[0064] A method for fabricating semiconductor devices by low-temperature etching of silicon-containing materials in high aspect ratio (HAR) structures using carbon oxyhalides is disclosed. The disclosed carbon oxyhalides may be amide halides. We believe that the disclosed carbon halides can both enhance the dehydration of water in the etched channel pores or features and provide a carbon source to enhance the selectivity of the etched dielectric material (e.g., SiO or a combination of SiO and SiN) to the mask material (e.g., carbon or carbon-doped material).

[0065] Currently developed low-temperature etching chemicals are used in high aspect ratio (HAR) applications, such as PF3 and HF for HAR patterning of dielectrics (e.g., SiO2 or SiO2 / SiN alternating films like 3D NAND). Due to the reaction of the etching gases with SiO and SiN in the substrate or device to be etched at low process temperatures < 0°C, the etching gases can provide an unprecedented amount of water to the features or holes etched in the substrate during the etching process, thereby forming a water layer in the etched features or holes. This water layer acts as a barrier layer to prevent the etching process from occurring (i.e., reducing the etching rate or stopping the etching). The primary purpose of low-temperature etching at such small features or holes in HAR etching processes is to remove water from the substrate or reduce the thickness of this water layer. It is said that PF3 used in low-temperature etching processes reacts with H2O to form H3PO4. However, this reaction is known to be slow compared to the reactivity of other phosphorus halides with water, see DeFrank et al., "Phosphofluoridates: Biological Activity and Biodegradation", Organofluorines, (2002); and "The Handbook of Environmental Chemistry", Vol. 3N, p. 303, Springer, Berlin, Heidelberg. https: / / doi.org / 10.1007 / 10721878_10.

[0066] This document discloses the use of the disclosed carbon oxyhalides or amide halides in place of PF3 or the addition of the disclosed carbon oxyhalides to PF3 and HF acid gas in cryogenic etching applications, which is advantageous for cryogenic etching processes. In addition to PF3 and HF, fluorocarbons or hydrofluorocarbons can be added to provide a carbon source, thereby enhancing selectivity for the mask (typically a carbon material). Although the concept of the HF +-(C=O)- family has been disclosed (WO 2023243569) for thermal etching at temperatures >20°C, it is not the same chemical family as that disclosed herein. Furthermore, due to the very fast reaction between the carbon oxyhalides or amide halides and dielectric materials (such as SiO2), very fast etching rates can be obtained, resulting in high wafer throughput during cryogenic etching.

[0067] This relates to the benefits of adding the disclosed carbon oxyhalides to the etching chemistry during low-temperature processes, particularly low-temperature plasma HAR etching processes. The disclosed carbon oxyhalides are expected to be low-GWP, low-carbon etching gases. Furthermore, by introducing oxygen into the etching gas, it is possible to add some carbon to the plasma etching process instead of providing polymers to block the features to be etched in the substrate during the plasma etching process, thereby contributing to mask selectivity. In other words, by adding the disclosed carbon oxyhalides, water can be removed from the etched features and HX (X-series halogens) can be generated. This additional generation of HX can be beneficial in increasing the etching rate during HAR etching. Furthermore, observing the boiling points of each substance generated with the disclosed carbon oxyhalides in the reactions of the following examples, it can be seen that the boiling point is lower than that of water, thus it is expected that HAR etching byproducts will be more easily removed from the etched features or holes due to increased volatility.

[0068] In some embodiments, the disclosed carbon oxyhalides may be CF3OF, C3O2F4, or CF3COF, used as additives in the etching chemistry of low-temperature plasma HAR etching processes. For example, CF3COF (trifluoroacetyl fluoride, CAS No.: 354-34-7) is an etchant used in low-temperature etching processes on silicon-containing substrates to manufacture semiconductor devices. CF3COF is expected to be a low-GWP, low-carbon precursor. Furthermore, by introducing oxygen into the precursor, it may not provide a polymer to block features etched in the substrate during the plasma process, but may instead add some carbon to the process, thereby contributing to the selectivity of the mask. CF3COF is known for its reaction with water (i.e., CF3COF + H2O → CF3COOH + HF). In other words, by adding CF3COF, water can be removed from the etched features and HF can be generated. This generation of additional HF can be beneficial in increasing the etching rate during HAR etching. Furthermore, observing the boiling points of each substance in the reaction reveals that the boiling points are lower compared to water, suggesting that byproducts will be more easily removed from the etched features or pores due to increased volatility. This reaction involves substances with boiling points: CF3COF (-59°C) + H2O (100°C) → CF3COOH (73°C) + HF (20°C).

[0069] Due to the high surface tension of water (72 dyn / cm at 20°C), water will remain as a thick passivation layer in the feature. CF3COOH has a much lower surface tension (13 dyn / cm at 20°C). Therefore, the CF3COF layer can be much thinner compared to the water in the feature, due to the combination of its reactivity with water and the lower surface tension and boiling point of its byproducts. Thus, the addition of HF generation, the removal of water, and the thinner passivation can lead to a high etching rate of SiN / SiO2 in HAR during low-temperature etching.

[0070] The disclosed carbon oxyhalides can be major families of acetylated halides, for example, Y3-CO-X and Y-(C=O)-X, where X and Y are each halides, such as F, Cl, Br, I; R1-CO-X, where X is a halide such as F, Cl, Br, I, and R1 is a fluorocarbon, hydrofluorocarbon, or hydrocarbon; R2-CO-R3, where R2 and R3 are fluorocarbons, hydrofluorocarbons, bromines, hydrobromines, chlorines, hydrochlorohydrocarbons or hydrocarbons, iodines, hydroiodides, such as CF3-CO-CF3, CH3-CO-CH3; R2-(C=O)-O-(C=O)-R3, where R2 and R3 are fluorocarbons, hydrofluorocarbons, bromines, hydrobromines, chlorines, hydrochlorohydrocarbons or hydrocarbons, iodines, hydroiodides, such as CF3-CO-CF3, CH3-CO-CH3; and COF-CxFyHz-COF Where x, y, and z are integers, such as (COF)-CF2-(COF).

[0071] It should be noted that the aforementioned acetylated halogen families R1-CO-X, R2-CO-R3, R2-(C=O)-O-(C=O)-R3, and COF-CxFyHz-COF can perform tasks similar to the C3O2F4 example below. Specifically, by adjusting the amount of carbon in the molecule, it is believed that molecules in the aforementioned acetylated halogen families can both enhance the dehydration of water in etched pores or features and provide some carbon to the etching process to enhance selectivity for mask materials (typically carbon or doped carbon such as boron-doped carbon).

[0072] The basic reaction of R1-CO-X proposed in this paper for dehydrating water from etched features / holes is as follows: R1-CO-X + H2O → R1-COOH + HX HX + SiO2 → SiX + H2O

[0073] For example, the following are reactions with specific molecules in the acetylated halogen family, with the boiling points of each substance listed in parentheses. CF3COCl (-27°C) + H2O (100°C) → CF3COOH (73°C) + HCl (-85°C) HCl (-85°C) + SiO2 (solid) → SiCl4 (58°C) + H2O (100°C) CF3COF (-59°C) + H2O (100°C) → CF3COOH (73°C) + HF (20°C) HF (20°C) + SiO2 (solid) → SiF4 (-90°C) + H2O (100°C)

[0074] If the chloride form of CF3COX is used instead of the fluoride form, although the chloride is much more reactive with water, the reaction of HCl with SiO2 is much slower, and the formation of the higher-boiling-point byproduct SiCl4 is not ideal. However, it will still dehydrate H2O, forming the more volatile byproducts CF3COOH and HCl.

[0075] The reaction is very fast in the case of C4F6O3 (CAS No.: 407-25-0, 2,2,2-trifluoroacetic anhydride, TFAA). The hydrolysis of acetic anhydride is known to be a rapid and extremely exothermic reaction, and this reaction has been widely used, for example, in nonlinear kinetics and multiple steady-state applications. C4F6O3 (40°C) + H2O (100°C) = CF3COOH (73°C) + HF (20°C) HF (20°C) + SiO2 (solid) → SiF4 (-90°C) + H2O (100°C)

[0076] Table 1 lists exemplary molecules included in the acetylated halogen families disclosed above. [Table 1] Chemical formula CAS# structure CF3OF 373-91-1 C3O2F4 5930-67-6 CF3COF 354-34-7 C3F6O 422-61-7 C2F3OI 354-36-9 C2F3OCl 354-32-5 C2O2F2 359-40-0 C4F6O3 (TFAA) 407-25-0 C4H3F3O 162880-35-5 C3H3F3O 2255428-10-3 C2HF3O 2925-22-6 C2HF3O 75-90-1 C3HF5O 663-74-1 C3HF5O 6065-84-5 C3HF5O 85592-82-1 C2HClF2O 381-72-6 C2HF3O 814-77-7 C2HClFIO 955374-72-8 C4HF5O3 406727-03-5 C4H2F4O3 401-67-2 C4H2F4O3 406727-04-6 C4H4F2O3 407-33-0 C4H3F3O3 1784758-59-3 C4H4F2O3 406727-05-7 C4H3F3O3 96-63-9 C2HClF2O 811-96-1 C2HBrF2O 353-79-7 C2HF2IO 1334483-62-3 C3F6O 684-16-2

[0077] The disclosed low-temperature plasma etching method includes exposing the substrate in a reaction chamber to etching gases from the aforementioned acetylated halogen family, namely R1-CO-X, R2-CO-R3, R2-(C=O)-O-(C=O)-R3 and COF-CxFyHz-COF, during the etching process and / or during the chamber conditioning process.

[0078] The disclosed low-temperature plasma etching method for selectively etching one or more silicon-containing films from a substrate to form holes by using a patterned mask layer deposited on top of one or more silicon-containing films includes: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below 25°C; and introducing an etching gas having the following general formulas into the reaction chamber: Y3-CO-X, Y-(C=O)-X, R1-CO-X, R2-CO-R3, R2-(C=O)-O-(C=O)-R3, and COF-CxFyHz-COF, wherein X and Y are each halogens selected from F, Cl, Br, I, R1 is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, R2 and R3 are each a fluorocarbon, hydrofluorocarbon, bromine, hydrobromocarbon, chlorine, hydrochlorocarbon, or hydrocarbon, iodine, or hydroiodine, and x, y, and z are integers; The etching gas is converted into plasma; and an etching reaction is allowed between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the hole.

[0079] Exemplary disclosed etching gases include CF3OF, C3O2F4, CF3COF, COF2, or C2O2F2. Preferably, the disclosed carbon oxyhalide etching gas can be C3O2F4, CF3COF, COF2, or C2O2F2 and its isomers.

[0080] The reaction chamber can be any accessory or chamber within the apparatus in which the etching method is performed, such as, but not limited to, reactive ion etching (RIE), CCP with a single or multiple frequency RF sources, inductively coupled plasma (ICP), microwave plasma reactor, or other types of etching systems capable of performing plasma processing (i.e., selectively removing a portion of the dielectric film or generating active material or depositing a film).

[0081] The reaction chamber is equipped with a parallel plate electrode plasma generator, wherein a 60 MHz high-frequency electromagnetic field is applied to the upper electrode and a 2 MHz electromagnetic field is applied to the lower electrode, with the gap between the electrodes maintained in the range of 10 to 35 mm. This combination of electric fields allows power in the range of 0-2000 W to be applied to the upper electrode and power in the range of 1500-7000 W to be applied to the lower electrode. The plasma can be generated with RF power ranging from about 25 W to about 100 kW. The plasma can be generated remotely or within the reaction chamber itself. The RF frequency of the plasma can range from 100 kHz to 1 GHz. The plasma can be pulsed or continuous wave. In some embodiments, the power applied to the chamber can range from 0 to a few kW of bias power and hundreds to thousands of kW of source power. Both the gas flow and the plasma can be pulsed or circulated in a variety of different processing steps.

[0082] The temperature and pressure within the reaction chamber are maintained under conditions suitable for the reaction of the processed film with the activated etching gas (e.g., the aforementioned acetal halide). For example, depending on the required etching parameters, the pressure in the chamber can be maintained between approximately 0.1 mTorr and approximately 1000 Torr, more preferably between approximately 1 mTorr and approximately 10 Torr, even more preferably between approximately 1 mTorr and approximately 1 Torr, and even more preferably between approximately 1 mTorr and approximately 30 mTorr. In the case of introducing a process gas mixture, the pressure in the etching chamber can be maintained between 1 and 30 mTorr during the plasma etching process. Similarly, the temperature of the substrate in the reaction chamber can be < 25°C, preferably < -50°C. Alternatively, the substrate temperature in the reaction chamber can range from approximately -196°C to approximately 300°C; more preferably, from approximately -196°C to approximately 60°C; even more preferably, from approximately -196°C to approximately 25°C; even more preferably, from approximately -196°C to approximately -50°C; and even more preferably, from approximately -196°C to approximately 0°C. The substrate temperature in the reaction chamber can be below approximately 0°C. The substrate can be cooled by a variety of sources, including commercially available coolers or other methods such as liquid N2.

[0083] The reaction chamber wall temperature can be approximately > 20°C, preferably < 150°C. Depending on the process requirements, the reaction chamber wall temperature can be approximately room temperature or higher but less than 60°C.

[0084] The disclosed low-temperature plasma etching method further includes exposing the substrate sequentially or simultaneously to a co-reactant before activating the plasma. That is, the co-reactant is added to the etching gas.

[0085] The co-reactants can be selected from O2, CO, CO2, NO, NO2, N2O, SO2, H2S or COS, O3, CxOyFz (x, y, and z are integers) such as COF2, C2O2F2, CxOyFzHm (x, y, z, and m are integers) such as alcohols, ketones, acids, ester molecules (such as CF3OH, CF3OCF3, (CF3)2C=O, CF3COOH), or combinations thereof. The co-reactant can be O2.

[0086] The co-reactant may be one or more additional hydrofluorocarbon or fluorocarbon etching gases added to the above-mentioned etching gases. The additional one or more hydrofluorocarbon or fluorocarbon etching gases may be selected from C4F6, C4F8, C4H2F6, CH2F2, CH3F, CHF3, CF4, C2F6, C3F8, SF6, NF3, C2F4, C3F6, C4F10, C5F8, C6F6, C1-C6CxFyHz molecules (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combinations thereof.

[0087] The co-reactant can be other gases added to the etching gas described above. For example, additives include H2, SF6, NF3, N2, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, HF, B2H6, and P-containing gases such as PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, and P(R)3 (where R is an alkyl or fluorinated alkyl group such as CF3), which can be added to the etching gas described above.

[0088] The co-reactant can be other sulfur-containing gases with the following general formulas added to the etching gas described above: SOmXn; and R-SOmXn, where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon. Exemplary examples of other sulfur-containing gases may include SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, and CF4SO2.

[0089] The co-reactant can be an inert gas or can be added to the etching gas described above. The inert gas is selected from Ar, Kr, Xe, Ne, N2, He or a combination thereof.

[0090] The substrate contains a silicon-containing material, such as SiO2, SiN, or Si. An example is an alternating layer of SiO and SiN used in 3D NAND applications. The silicon-containing film or material includes a SiObHcCdNe layer, where a > 0, b, c, d, and e ≥ 0, selected from silicon oxide, silicon nitride, crystalline Si, polycrystalline silicon, amorphous silicon, low-k SiCOH, SiOCN, SiC, SiON, or a stack of alternating silicon oxide and silicon nitride (ONON) films or alternating silicon oxide and polycrystalline silicon (OPOP) films.

[0091] A mask layer or mask material is attached to the top of the silicon-containing film or material. The mask material may be amorphous carbon, doped amorphous carbon, spin-coated carbon (SOC), Si, SiN, Al, AlO, Ti, TiO or other metal and metal oxide masks, or other nitride layers (such as TiN) with or without dopants.

[0092] The disclosed carbon oxyhalide etching gases (i.e., the aforementioned acetylated halides) are supplied in cylinders in various fill volumes, pressures, and specifications. Preferably, the material has a low moisture content of <40 ppm, more preferably <10 ppm. The disclosed carbon oxyhalide etching gases can be purified by distillation, adsorption using molecular sieves, or other common and known methods in the art to remove key impurities such as chlorinated substances or organochlorides, other fluorocarbons, hydrofluorocarbons, chlorofluorocarbons (CFCs), impurities from the air (N2, O2, CO2), moisture (H2O), HF, and other hydrocarbons (CH4, etc.). Some impurities can form azeotropes; therefore, other purification methods may be required to separate them using chemical means.

[0093] After etching, the substrate can be heated to a temperature greater than the etching process temperature, for example, >0°C, so that the reaction byproducts evaporate and leave the reaction chamber into a vacuum.

[0094] The disclosed carbon oxyhalide etching gas not only has a much lower GWP than standard fluorinated compound etching gases, but also produces lower CO2 equivalent emissions from the etching process. The disclosed low-temperature plasma etching method uses the disclosed carbon oxyhalide as the etching gas to create pores or features in silicon-containing films, such as channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, contact etching, slot etching, self-aligned contacts, self-aligned vias, supervias, etc. The resulting pores can have an aspect ratio ranging from about 5:1 to about 500:1, preferably from about 20:1 to about 400:1. The resulting pores can have a diameter ranging from about 0.1 nm to about 500 nm, preferably from about 0.1 nm to about 500 nm, and more preferably less than 100 nm. The resulting vias can have an aspect ratio greater than 1:1, preferably greater than 5:1, more preferably greater than 10:1, and even more preferably greater than 20:1. The resulting vias can have an aspect ratio ranging from 1:1 to 5:1. For example, those skilled in the art will recognize that channel hole etching in a silicon-containing film produces vias with an aspect ratio greater than 50:1.

[0095] The disclosed low-temperature plasma etching method is not limited in any way to the above-described experimental conditions. The type of plasma etching tool (e.g., capacitively coupled or inductively coupled plasma), process conditions (e.g., pressure, power, temperature, process duration), process gas mixture, combination and proportion of gases in the process gas mixture, gas flow rate, workpiece, and plasma etching chamber itself can be varied for each process and during the process.

[0096] In summary, the disclosed low-temperature plasma etching method provides the use of carbon oxyhalide etching gases (i.e., the aforementioned acetylated halides) to enhance the dehydration of water in the etched pores or features and to provide some carbon to the etching process to enhance selectivity for mask materials (typically carbon or doped carbon such as boron-doped carbon). Furthermore, compared to commonly used materials (e.g., CF4, C4F8, CH2F2), the disclosed carbon oxyhalides have a lower GWP, enabling more environmentally friendly processes. Examples

[0097] A more detailed description of the disclosed method is provided below by way of example. However, the disclosed method is not limited in any way to the examples presented, and the process conditions, process gas mixtures, the combination and proportion of gases in the gas mixtures, the workpiece, and the plasma etching chamber itself can be changed.

[0098] In the following examples, the primary plasma etching source can be CCP plasma, but other sources such as ICP, microwave, ECR, etc., may also be included. The plasma can be used as a continuous source or as a pulsed plasma with a specific frequency and duty cycle. The temperature of the substrate surface can be cooled or raised by a cryogenic cooler, or by a liquid N2 supply and heating stage. Additional fluorocarbon gases can be added to slightly adjust the etching performance. Additional inert gases such as Kr, Xe, Ne, and hydrogen source gases such as H2, as well as hydrocarbons, can be added. The mask material may include TiN or other metal nitride materials, SiN, Si, carbon materials, etc.

[0099] Example 1: CF4 vs. C3O2F4 (CAS # 5930-67-6) The process conditions used to measure the etching rate are described in Table 2 below, where four common materials used in semiconductor processing (including SiO2, SiN, polycrystalline silicon (p-Si), and boron-doped amorphous carbon (aC(B))) are placed on a Si carrier wafer and processed in a 200 mm CCP plasma etching chamber. The etching gas flow rates in Table 2 represent the CF4 and C3O2F4 gases, respectively. The boron composition in the amorphous carbon film is 35%. Etching data for CF4 are shown in Figure 1, and etching data for C3O2F4 are shown in Figure 2. [Table 2] RF source [W] 750 RF bias [W] 1500 Pressure [millitor] 30 Etching gas flow rate (sccm) 15 O2 flow rate [sccm] change Ar flow rate [sccm] 250 He [trust] 15 Wafer T [°C] 20

[0100] As shown in Figure 1, CF4 has low carbon content, making it suitable for low-temperature etching because it does not clog features. Adding O2 is not recommended because it severely degrades the mask thickness during etching.

[0101] At O2 = 0 sccm and 5 sccm, the etching rates of SiO2 and SiN using C3O2F4 are always higher than those of CF4, as shown in Figure 2. The retention of the carbon mask is comparable between the two processes. Therefore, the mask selectivity is more favorable to the C3O2F4 chemistry compared to CF4.

[0102] If the O2 flow rate is slightly increased to 5 sccm, the etching rate of SiO2 and SiN via C3O2F4 is still higher than that of CF4. Meanwhile, CF4 may not retain the mask at 5 sccm O2. This result indicates that C3O2F4 provides a wider O2 process window, which is beneficial for process control systems.

[0103] Example 2. COF2 (Carbonyl Fluoride, CAS No.: 353-50-4) vs. C2O2F2 (CAS No.: 359-40-0) The etching rates of COF2 (Figure 3) and C2O2F2 (Figure 4) were measured as a function of O2 flow rate using the same process conditions as described in Example 1 and Table 2. As can be seen from Figures 4 and 2, at an O2 flow rate of 0 sccm, C2O2F2 and C3O2F4 exhibit very low etching rates for boron-doped aC (a common mask material), and these etching rates are lower than those for COF2 shown in Figure 3. The data at an O2 flow rate of 0 sccm are important because it is preferable not to add O2 during the process to maximize mask selectivity.

[0104] Example 3. SiO2 Etching Rate and SiO2 Selectivity Relative to Boron-Doped aC Masks. Figure 5 compares the selectivity of SiO2 relative to boron-doped aC masks using etching gases CF4SO2, COF2, C2O2F2, and C3O2F4. Figure 6 is a bar graph comparing the SiO2 etching rates using etching gases CF4SO2, COF2, C2O2F2, and C3O2F4, respectively.

[0105] Despite having a similar COF structure, COF2 does not offer similar SiO2 selectivity for aC compared to its counterparts C2O2F2 and C3O2F4. Therefore, it is not obvious that the mere presence of a COF (i.e., -(C=O)-F) structure does not necessarily imply that it will exhibit the same behavior in plasma etching processes. In cryogenic etching processes, fluorocarbon molecules enhance the selectivity of dielectric etching to the mask. In this paper, the disclosed molecules both enhance mask selectivity and act as dehydrating agents to remove water from channel pores. As can be seen from Figure 5, the selectivity of SiO2 etching relative to a carbon mask is C3O2F4 > C2O2F2 > COF2 ~ CF4SO2. Therefore, surprisingly, we expect that molecules like C2O2F2, CF3COF, and C3O2F4 can provide enhanced etch selectivity of SiO2 relative to the mask material compared to COF2, while also providing dehydration of water, despite each molecule having the same -(C=O)-F functional group.

[0106] The SiO2 selectivity for aC in C2O2F2 and C3O2F4 is significantly increased compared to that in COF2 and CF4SO2, as shown in Figures 5 and 6. This data indicates that C2O2F2 and C3O2F4 are much richer in fluorine than COF2. This may be advantageous for etching oxides at lower temperatures.

[0107] Example 4. Etching rates of blanket film by CF4 and CF3COF were compared at a plasma source power of 1125 W. The etching rates of SiO2, aC, SiN, and p-Si by CF4 and CF3COF on the blanket film were compared. In the CCP plasma etching tool, the source plasma power was 1125 W, the bias power was 2250 W, the pressure was 22 mTorr, the argon flow rate was 70 sccm, and the wafer temperature was 20°C. The etching results using CF4 and CF3COF are shown in Table 3 below. Etching rates are in nm / min. [Table 3] CF4 = 50 sccm O2 = 0 sccm CF4 = 40 sccm O2 = 10 sccm CF3COF = 50 sccm O2 = 0 sccm CF3COF = 40 sccm O2 = 10 sccm aC Etching Rate 78 110 103 124 SiO2 etching rate 565 371 544 442 SiN etching rate 75 131 107 134 p-Si etching rate 71 95 82 93

[0108] As can be seen from the results, the etching rate of SiO2 under 40 sccm etching gas and 10 sccm O2 conditions shows that CF3COF > CF4, an increase of approximately 20%, with similar etching rates for mask materials aC and p-Si. This performance is very important and can be beneficial for high aspect ratio etching. Furthermore, it can be seen that CF3COF provides an increased SiN etching rate under 0 sccm O2 process conditions. This may be beneficial for 3D NAND etching.

[0109] Example 5. The etching rates of the blanket coating with CF4 and CF3COF were repeated under the same process conditions as in Example 4, without O2 and with a plasma source power of 500 W, except that the source power was 500 W, the etching gas flow rate was 50 sccm, and no O2 was added. The etching results with CF4 and CF3COF are shown in Table 4. Etching rates are in nm / min. [Table 4] CF4 CF3COF aC Etching Rate 64 93 SiO2 etching rate 445 448 SiN etching rate 68 92 pSi etching rate 69 80

[0110] As can be seen from the results and similar to Example 4, at a source power of 500 W, CF3COF increases the etch rate of SiN by 34% compared to CF4 at a similar SiO2 etch rate. This may be beneficial for high aspect ratio etching in 3D NAND. Furthermore, for CF3COF, as seen in Examples 4 and 5, increasing the source power leads to an increase in the etch rate of SiO2 and SiN more than that of aC and p-Si. Similarly, increasing the source power increases the etch rate of SiO2 and SiN for both CF4 and CF3COF, while increasing the aC mask increases it less, thus giving CF3COF a selective benefit. The increased etch rate of SiO2 and SiN by CF3COF under certain process conditions, along with the dehydration effect, may be beneficial for low-temperature etching applications, despite both molecules having the same number of F atoms. Overall, CF3COF provides unexpected process benefits compared to CF4.

[0111] Example 6. QMS of CF3COF and CF4. The QMS of CF3COF and CF4 were measured at 26 eV. The percentage of each substance (m / z) for each molecule is shown in Table 5. [Table 5] CF (31) CF2 (50) CF3 (69) COF (47) CF4 2% 5% 93% 0% CF3COF 2% 19% 65% 14%

[0112] As can be seen, CF3COF and CF4 produce very different decompositions of different substances in QMS, indicating that they will produce different substances and have different etching characteristics in the plasma etching process. CF3COF has a CF3 / Ar peak ratio of 0.15 and CF4 has 0.04. Therefore, surprisingly, CF3COF produces about 3.5 times more CF3 material than CF4. CF3 is a very important etchant.

[0113] 35

[0114] Example 7. GWP Emissions of CF3COF and CF4. The CO2 equivalent relative GWP emissions of plasma etching processes of CF3COF and CF4 were measured. In a CCP plasma etching tool, the source plasma power was 1125 W, the bias power was 2250 W, the pressure was 22 mTorr, the argon flow rate was 70 sccm, and the wafer temperature was 20°C. The etching gas flow rate was 50 sccm, and the argon flow rate was 70 sccm. Emissions were measured using FTIR after the etching tool vacuum pump and before emission reduction. The relative normalized CO2 equivalent of CF3COF was 65% smaller than that of CF4, indicating that CF3COF produces significantly less CO2 equivalent emissions and is a much more environmentally friendly etching gas. Surprisingly, CF3COF produced 86% less CF4 in the emission stream compared to CF4, although the QMS of CF3COF showed a much higher CF3 content. Therefore, CF3COF is more emission-friendly because CF4 is less effective at reducing emissions in most emission reduction systems (plasma or thermal burners).

[0115] It should be understood that those skilled in the art can make many additional changes to the details, materials, steps, and arrangements of parts that have been described and elucidated to explain the nature of the invention as set forth in the appended claims, within the principles and scope of the invention. Therefore, the invention is not intended to be limited to the specific embodiments given above and / or in the accompanying drawings.

[0116] Although embodiments of the invention have been shown and described, those skilled in the art can modify them without departing from the spirit or teachings of the invention. The embodiments described herein are exemplary and not restrictive. Many variations and modifications of the components and methods are possible and are within the scope of the invention. Therefore, the scope of protection is not limited to the embodiments described herein, but is defined only by the following claims, the scope of which should include all equivalents of the subject matter of the claims. [Simplified Explanation of the Diagram]

[0063] To further understand the nature and purpose of the present invention, reference should be made to the following detailed description in conjunction with the accompanying drawings, in which similar elements are given the same or similar reference numerals, and wherein: [Figure 1] is a bar graph comparing the etching rates of common materials SiO2, SiN, p-Si and aC masks used in semiconductor processing when using CF4 as an etchant; [Figure 2] is a bar graph comparing the etching rates of common materials SiO2, SiN, p-Si and aC masks used in semiconductor processing when using C3O2F4 as an etchant; [Figure 3] is a bar graph comparing the etching rates of common materials SiO2, SiN, p-Si and aC masks used in semiconductor processing when using COF2 as an etchant; [Figure 4] is a bar graph comparing the etching rates of common materials SiO2, SiN, p-Si and aC masks used in semiconductor processing when using C2O2F2 as an etchant; [Figure 5] is a bar graph comparing the selectivity of SiO2 for aC masks when using etching gases COF2, C2O2F2 and C3O2F4 respectively; and [Figure 6] is a bar graph comparing the etching rates of SiO2 when using etching gases COF2, C2O2F2 and C3O2F4 respectively. [Biomaterial Storage]

[0118] None

Claims

1. A low-temperature etching method for selectively etching one or more silicon-containing films from a substrate to form holes using a patterned mask layer deposited on top of one or more silicon-containing films, the method comprising: The substrate is installed in the reaction chamber; The substrate is cooled to a temperature below 0°C; CF3OF or an etching gas having the following general formula R1-CO-X, COF-CxFyHz-COF is introduced into the reaction chamber, where X is a halogen selected from F, Cl, Br, I, R1 is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, R2 and R3 are each a fluorocarbon, hydrofluorocarbon, bromine, hydrobromide, chlorine, hydrochloric, or hydrocarbon, iodine, or hydroiodine, and x, y, and z are integers; the etching gas is converted into a plasma; and an etching reaction is allowed between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the hole.

2. The method as described in claim 1, further comprising adding one or more hydrofluorocarbon or fluorocarbon etching gases to the etching gas, wherein the one or more hydrofluorocarbon or fluorocarbon etching gases are selected from C4F6, C4F8, C4H2F6, CHF3, CH2F2, CH3F, CF4, C2F6, C3F8, SF6, NF3, C2F4, C3F6, C4F10, C5F8, C6F6, C1-C6 CxFyHz molecules (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combinations thereof.

3. The method as described in claim 1, further comprising adding a co-reactant to the etching gas, wherein the co-reactant is selected from H2, SF6, NF3, N2, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, HF, B2H6, and a P-containing gas selected from PF3, PCl3, PBr3, POCl3, POCl5, PF5, PCl5, POF3, POCl3, POF3, PH3, P(R)3—wherein R is an alkyl or fluorinated alkyl group, SOF2, SOCl2, SOClF, SO2F2, SO2FCl, SO2Cl2, or CF4SO2.

4. The method as described in claim 1, further comprising adding a co-reactant to the etching gas, wherein the co-reactant is selected from O2, CO, CO2, NO, NO2, N2O, SO2, H2S, COS, O3, CxOyFz (x, y, and z are integers), and CxOyFzHm (x, y, z, and m are integers) selected from alcohols, ketones, acids, and ester molecules.

5. The method as claimed in claim 1, further comprising adding a co-reactant to the etching gas, wherein the co-reactant is an inert gas selected from Ar, Kr, Xe, Ne, N2, He, or combinations thereof added to the etching gas.

6. The method as described in claim 1, wherein, The etching gas system is C3O2F4.

7. The method as described in claim 1, wherein, The etching gas system is CF3COF.

8. The method as described in any one of claims 1 to 7, wherein, The substrate has a temperature range of approximately -196°C to approximately 300°C.

9. The method as described in any one of claims 1 to 7, wherein, The aspect ratio of the hole ranges from approximately 5:1 to approximately 500:

1.

10. The method as described in any one of claims 1 to 7, wherein, The pores have diameters ranging from approximately 0.1 nm to approximately 500 nm.

11. A low-temperature etching method for selectively etching one or more silicon-containing films from a substrate to form holes using a patterned mask layer deposited on top of one or more silicon-containing films, the method comprising: The substrate is installed in the reaction chamber; The substrate was cooled to a temperature below approximately 0°C. Etching gas CF3OF, CF3COF, or C3O2F4 is introduced into the reaction chamber; the etching gas is converted into plasma; and an etching reaction is allowed between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the hole.

12. A low-temperature etching method for selectively etching one or more silicon-containing films from a substrate to form holes using a patterned mask layer deposited on top of one or more silicon-containing films, the method comprising: The substrate is installed in the reaction chamber; The substrate was cooled to a temperature below approximately 0°C. Etching gases CF3OF, CF3COF, or C3O2F4 are introduced into the reaction chamber; co-reactant O2 is added to the reaction chamber to convert the etching gas into plasma; and an etching reaction is allowed between the plasma and the one or more silicon-containing films, such that the one or more silicon-containing films are selectively etched relative to the patterned mask layer to form the hole.

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