Cryogenic etching using SOF2 and its family

Abstract

A cryogenic etching method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber, cooling the substrate to a temperature below approximately 25°C, introducing an etching gas having a general formula SOmXn and R- SOmXn, where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, into the reaction chamber, converting the etching gas to a plasma, and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture.

Description

CRYOGENIC ETCHING USING SOF2AND ITS FAMILYCross Reference to Related Applications

[0001] This application claims priority to US Patent Application No. 63 / 655,897, filed June 4, 2024, the entire contents of which are incorporated herein by reference.Technical Field

[0002] The present invention relates to a method of cryogenic plasma etching silicon- containing materials using an etching gas SOF2or an etching gas from SOF2families of SOmXn and R-SOmXn, where m and n are integers, X is halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, to manufacture semiconductor chips, such as 3D NAND flash and DRAM chip manufacturing.BackgroundF vo

[0003] SOF2( F ) is a known etchant in plasma etch as shown in prior art below. SOF2is also known as its reactivity with water at room temperature. The reaction is SOF2+ H2O > HF + SO2(Holleman, Arnold F. (2001), Inorganic Chemistry, p542.).

[0004] So far, there have not been publications or disclosures showing SOF2(or similar family of SCXFy, where x and y are integers) in combination with HF in high aspect ratio (HAR) in cryogenic and / or low temperature. Specifically such a combination is used to remove water cr dehydration from channel holes in cryogenic etch. Another benefit of such chemistry is its capability to etch SiO2and SiN at the same rate.

[0005] JP3298205B2 discloses using SOF2to etch SIO2via at room temperature. The example also shews the etching process at - 30“C.[Q006] US6919274B2 discloses LSI device etching method and apparatus thereof, in which SOF2and SO2F2plasma etches Silicon-containing film to prevent Cu diffusion. The process temperature can be set in a range of - 40 to 100°C, preferably 40 to 60°C. The LSI device to be etched includes Cu interconnection, a low-k film, and a diffusion prevention film containing silicon (Si) for preventing diffusion of Cu into the low-k film. The LSI device etching method includes the step of: selectively etching the diffusion prevention film against the low-k film, by use of a gas containing sulfur (S) as an etching gas. It is also disclosed that it is preferable that a gas containing N and F is mixed with the etching gas. NF3, NFSO, or N2F4is used far a gas containing N and F. They also disclose a gaswhich generates a radical or reaction product with a smaii binding energy with various kinds of surfaces is selected such as SiF4, N2, CO2, SiFxClyBr^ (x, y, z=0-4) can be adoptabie. And as the gas to generate these gases, N-containing gases such as NF3, N2, NH3and others, Ch, HCI, HBr, HF, or Hi are disciosed. A sulfur-containing gas, SO2, is used as the etching gas to selectively etch the diffusion prevention film (SiC) against the low-k film (SiOC). In this embodiment, SO3, SCF2, SO2F2, SON:<, SONxFy, or SH2can be used instead of SO2. in another embodiment, SO2 is used as an etching gas to etch the SiC mask material against the SiO2low-k layer. In this case, gases of SO3, SO, S2O3, SOF2, SO2F2, SONx, SONxFy, or SH2can be used in addition to SO2. In another example they mix NF3with SO2to etch the mask material selective to the low-k film. In addition a gas containing hydrogen (H) and halogen, such as HCI, HBr, HF, HI, CHF3, or CH2F2is mixed with the mixture gas to enhance the perpendicular etching of trenches and holes of the SiC mask against the SiOC low k film layer. Therefore this teaches that an S gas such as SOF2 can be mixed with a gas containing H and halogen such as HF to etch a mask material like SiC selective to a low k film SiOC layer including at temperatures down to - 4O':’C.

[0007] WO2015078749 discloses an etching process that shows SOF? can be used as a replacement for SF4and O2. The process temperature is from 200 to 500°C. The described process is preferred to be Bosch process.

[0008] US5314576A discloses a dry etching method using polythiazyl (sn)x protective layer that claims SOF2to be used to etch Silicon contains film. The process temperature was mentioned to be at temperatures as low as -30°C in an example.[Q009] KR100485743 Bl discloses cleaning gas for semiconductor production equipment in which SOF2and SO2O2to be used as cleaning gas. The process temperature is specified to be above 50cC. The plasma source is microwave.[001 G] US5376234 A discloses a dry etching method in which SOF2is used to etch Silicon compound layer such as SiO2. The process temperature is as low as -30°C In an example.

[0011] KR20020027520 discloses sidewall polymer forming gas additives far etching processes showing the etching of Si containing substrates via etchant gas such as SOF2. No specific temperature is disclosed. Suitable etchant gases for etching the layers are, far example, HCI, BCI3, HBr, Br2, Cl2, HI, CCk SiCk SFg, F, NF3, HF, CF3, CF4, CH3F, CHF3, C2H2F2, C2H4FS, C2F6, C3FS, C4F8, C2HF5, C4F10, CF2CI2, CFCIs, O2, N2, He and mixtures thereof.

[0012] Duluard et al. (Plasma Sources Sci. Technol. 17 045008, 2008) discloses SO2 passivating chemistry for silicon cryogenic deep etching in which cryogenic etching of Silicon and SiO2 via chemistry of SF6 / SO2plasma. The surface reactions involving SOF and SO2 species with F radicals are favored, providing a greater number of SOF2and SO2F2molecules in the gas phase. In SF6 / O2plasma, a higher rate of O radicals available for reacting with SFXspecies can account for the greater concentration in SOF4molecules.

[0013] Currently, generation of cryo-etch chemistry uses PF3and HF for HAR application, such as for high aspect ratio patterning of dielectrics such as SiC>2 or SiO2 / SiN films like 3DNAND (see for example US 2023 / 0127467 and Kihara et al 2023 Symposium on VLSI Technology and Circuits Digest of Technical Papers). Due to reaction with SiO and SiN materials in the high aspect ratio feature, and its low process temperature <0°C, such chemistry provides a large unprecedented amount of water in the deep feature of the device, i.e., the reaction is SiO2 + HF -> SiFx + H2O. This water layer acts as a barrier to prevent the etching process from happening (i.e., lower etching rate or etch stop). The primary objective for cryo-etching at such a small feature is to remove water from the high aspect ratio structure or to reduce the water layer thickness. As such the etching rate is a key performance metric for semiconductor manufacturing, especially for memory such as 3DNAND and DRAM where high throughput it critical. Increasing the etching rate thus increases the process throughput. The use of PF3in the cryo-etching process is said to react with H2O to form H3PO4and to boost the etch rate. However, this reaction is known to be slow and results in the byproduct H3PO4that is high boiling point compound and forming HF that is reactive.

[0014] Thus, there is a need to explore new etchant chemistry for cryo-etching in semiconductor industry.Summary

[0024] Disclosed is a cryogenic etching method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below approximately 25°C; introducing an etching gas having a general formulaSOmXn; andR-SOmXn,where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, into the reaction chamber; converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture. The disclosed deposition method may include one or more of the following features:• further comprising adding other etching gases such as HF, HOF, H2, SF6, NF3, N2, NH3, Cl2, BCI3, BF3, Br2, F2, FNO, FNO3, HBr, HCI, HI, IF5, IF7, B2H6, and P- containing gases such as PF3, PCI3, PCI5, POCI3, POCI5, PBr3, PH3, POCI3, PF5, POF3, PH3and P(R)3where R is an alkyl or fluorinated alkyl group;• the other etching gas being HF;• 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, C2FS, C3FS, SFe, NF3, C2F4, C3Fe, C4Fw, CsFs, CeFe, C-i-Ce CxFyHzmolecule (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combination thereof;• further comprising adding a co-reactant to the etching gas;• the co-reactant being selected from O2, CO, CO2, NO, NO2, N2O, SO2, H2S, COS, O3, CxOyFz (x, y and z are integers) selected from COF2, C2O2F2, CxOyFzHm (x, y, z and m are integers) selected from alcohol, ketone, acidic, ester type molecule selected from CF3COF, CF3OH, CF3OCF3, (CF3)2C=O, CF3COOH, or combinations thereof;• the co-reactant being O2;• the co-reactant being an inert gas;• the inert gas being selected from Ar, Kr, Xe, Ne, N2, He or combination thereof;• the etching gas being thionyl fluoride (SOF2, CAS NO.: 7783-42-8);• the etching gas being SOX2, where X is a halogen selected from F, Cl, Br or I;• the etching gas being selected from SOF2, SOCI2, or SOCIF;• the etching gas being SO2X2, where X is a halogen selected from F, Cl, Br or I;• the etching gas being selected from selected from SO2F2, SO2FCI, or SO2CI2;• the etching gas being CX4SO2, where X is a halogen selected from F, Cl, Br or I;• the etching gas being CF4SO2;• the etching gas being SOF2(CAS No.:7783-42-8), SOFCI (CAS No.: 14177-25-4), SOCI2(CAS No.:7719-09-7), SOBr2(CAS No.:507-16-4), SOI2(CAS No.:55032-43-4), SO2F2(CAS No.:2699-79-8), SO2FCI (CAS No.: 13637-84-8), SO2CI2(CAS No.:7791-25- 5), SO2Br2(CAS No.:74474-90-1), SO2I2(CAS No.:47988-86-3), CF4SO2(CAS No.:335- 05-7), SF4(CAS No.:7783-60-0), SOF4(CAS No.: 13709-54-1), SOF2CI2(CAS No. :2410796-75-5), SOBr4(CAS No.:82868-25-5), SO2F3(CAS No.:448957-65-1), SO2F4(CAS No.: 1509880-37-8), SOI4(CAS No.:82868-29-9), SOFBr (CAS No.:81539-20-0), SO2FBr (CAS No.: 13536-61 -3), SF4NH (CAS No.:80594-79-2), SO2FI (CAS No.:1694640- 87-3), SOF2IN (CAS No.:30708-83-9), S2F4(CAS No.:27245-05-2), SF2ONH (CAS No.:20994-96-1), SF3CI (CAS No.:65082-54-4), SF2CI2(CAS No.: 102487-42-3), SF2ONCI (CAS No.: 13816-63-2), SF3ON (CAS No.: 13816-64-3), S2F4(CAS No.: 1631959-27-7), S2F3CI (CAS No.:27357-77-3), SBr4(CAS No.:73373-25-8), Si5(CAS No.:82868-21-1), SBr3OH (CAS No.:62339-08-6), CF2S (CAS No.:420-32-6), CF2S (CAS No.: 1275589-65- 5);• the etching gas being SOF2families;• the SOF2families including SOmXn, where m and n are integers, X is a halide such as F, Cl, Br, etc., and a combination of halides if n >2, such as F, Cl, for example, SOFCI, SO2FCI;• the SOF2families including R-SOm-Xn, where m and n are integers, X is a halide such as F, Cl, Br, etc., and X is a combination of halides if n >2, such as F, Cl, for example, SOFCI, SO2FCI and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon;• Exemplary etching gases in the SOF2families may including SOF2, SO2F2, SOCI2, SO2CI2, SOI2, CF3-SO2-F;• the temperature of the substrate in the reaction chamber being < 25°C;• the temperature of the substrate in the reaction chamber being below approximately - 40°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately 300°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately 60°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately - 40°C;• an aspect ratio of the aperture ranging from 1 :1 to 5:1 ;• an aspect ratio of the aperture being above 1 :1 ;• an aspect ratio of the aperture being above 5:1 ;• an aspect ratio of the aperture being above 10: 1 ;• an aspect ratio of the aperture being above 20: 1 ;• an aspect ratio of the aperture ranging from approximately 5:1 to approximately 500:1 ;• an aspect ratio of the aperture ranging from approximately 20:1 to approximately 400:1 ;• an aperture having a diameter ranging from approximately 0.1 nm to approximately 500 nm;• an aperture having a diameter ranging from approximately 0.1 nm to approximately 300 nm;• the aperture having a diameter less than 100 nm;• after the aperture is formed, the temperature of the substrate being increased to greater than - 40°C; and• SOF2and other gas from the SOF2family have lower GWP compared to commonly used ones (e.g., CF4, C4F8, CH2F2), enabling more eco-friendly processes.

[0015] Also disclosed is a cryogenic etching method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below approximately 25°C; introducing an etching gas SOF2, SO2F2orCF4SO2into the reaction chamber; converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture. The disclosed deposition method may include one or more of the following features:• further comprising adding other etching gases such as HF, HOF, H2, SF6, NF3, N2, NH3, Cl2, BCI3, BF3, Br2, F2, FNO, FNO3, HBr, HCI, HI, IF5, IF7, B2H6, and P- containing gases such as PF3, PCI3, PCI5, POCI3, POCI5, PBr3, PH3, POCI3, PF5, POF3, PH3and P(R)3where R is an alkyl or fluorinated alkyl group;• further comprising adding one or more hydrofluorocarbon or fluorocarbon etchinggases to the etching gas, wherein the one or more hydrofluorocarbon or fluorocarbon etching gases are selected from C4F6, C4F8, C4H2F6, CHF3, CH2F2, CH3F, CF4, C2FS, CsFs, SFe, NF3, C2F4, C3F6, C4FW, CSFS, CSFS, C-i-Cs CxFyHzmolecule (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, CsH2F4, or combination thereof;• further comprising adding a co-reactant to the etching gas;• the co-reactant being selected from O2, CO, CO2, NO, NO2, N2O, SO2, H2S, COS, O3, CxOyFz (x, y and z are integers) selected from COF2, C2O2F2, CxOyFzHm (x, y, z and m are integers) selected from alcohol, ketone, acidic, ester type molecule selected from CF3COF, CF3OH, CF3OCF3, (CF3)2C=O, CF3COOH, or combinations thereof;• the co-reactant being HF;• the co-reactant being O2;• the co-reactant being an inert gas;• the inert gas being selected from Ar, Kr, Xe, Ne, N2, He or combination thereof;• the etching gas being thionyl fluoride (SOF2, CAS NO.: 7783-42-8);• the etching gas being SOF2;• the etching gas being SO2F2;• the etching gas being CF4SO2;• the temperature of the substrate in the reaction chamber being < 25°C;• the temperature of the substrate in the reaction chamber being below approximately - 40°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately 300°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately 60°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately - 40°C;• an aspect ratio of the aperture ranging from 1 :1 to 5:1 ;• an aspect ratio of the aperture being above 1 :1 ;• an aspect ratio of the aperture being above 5:1 ;• an aspect ratio of the aperture being above 10: 1 ;• an aspect ratio of the aperture being above 20: 1 ;• an aspect ratio of the aperture ranging from approximately 5:1 to approximately500:1 ;• an aspect ratio of the aperture ranging from approximately 20:1 to approximately 400:1 ;• an aperture having a diameter ranging from approximately 0.1 nm to approximately 500 nm;• an aperture having a diameter ranging from approximately 0.1 nm to approximately 300 nm;• the aperture having a diameter less than 100 nm;• after the aperture is formed, the temperature of the substrate being increased to greater than - 40°C; and• SOF2and other gas from the SOF2family have lower GWP compared to commonly used ones (e.g., CF4, C4F8, CH2F2), enabling more eco-friendly processes.

[0016] Also disclosed is a cryogenic etching method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below approximately 25°C; introducing an etching gas SOF2, SO2F2orCF4SO2into the reaction chamber; adding a co-reactant HF into the reaction chamber converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture. The disclosed deposition method may include one or more of the following features:• further comprising adding other etching gases such as HF, HOF, H2, SF6, NF3, N2, NH3, Cl2, BCI3, BF3, Br2, F2, FNO, FNO3, HBr, HCI, HI, IF5, IF7, B2H6, and P- containing gases such as PF3, PCI3, PCI5, POCI3, POCI5, PBr3, PH3, POCI3, PF5, POF3, PH3and P(R)3where R is an alkyl or fluorinated alkyl group;• 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, C2FS, C3FS, SFe, NF3, C2F4, C3Fe, C4FIO, CsFs, CeFe, Ci-Ce CxFyHz molecule (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combination thereof;• further comprising adding a co-reactant to the etching gas;• the co-reactant being selected from O2, CO, CO2, NO, NO2, N2O, SO2, H2S, COS, O3, CxOyFz (x, y and z are integers) selected from COF2, C2O2F2, CxOyFzHm (x, y, z and m are integers) selected from alcohol, ketone, acidic, ester type molecule selected from CF3COF, CF3OH, CF3OCF3, (CF3)2C=O, CF3COOH, or combinations thereof;• the co-reactant being O2;• the co-reactant being an inert gas;• the inert gas being selected from Ar, Kr, Xe, Ne, N2, He or combination thereof;• the etching gas being thionyl fluoride (SOF2, CAS NO.: 7783-42-8);• the etching gas being SOF2;• the etching gas being SO2F2;• the etching gas being CF4SO2;• the temperature of the substrate in the reaction chamber being < 25°C;• the temperature of the substrate in the reaction chamber being below approximately - 40°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately 300°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately 60°C;• the temperature of the substrate in the reaction chamber ranging from approximately - 196°C to approximately - 40°C;• an aspect ratio of the aperture ranging from 1 :1 to 5:1 ;• an aspect ratio of the aperture being above 1 :1 ;• an aspect ratio of the aperture being above 5:1 ;• an aspect ratio of the aperture being above 10: 1 ;• an aspect ratio of the aperture being above 20: 1 ;• an aspect ratio of the aperture ranging from approximately 5:1 to approximately 500: 1 ;• an aspect ratio of the aperture ranging from approximately 20: 1 to approximately 400: 1 ;• an aperture having a diameter ranging from approximately 0.1 nm to approximately 500 nm;• an aperture having a diameter ranging from approximately 0.1 nm to approximately300 nm;• the aperture having a diameter less than 100 nm;• after the aperture is formed, the temperature of the substrate being increased to greater than - 40°C; and• SOF2and other gas from the SOF2family have lower GWP compared to commonly used ones (e.g., CF4, C4F8, CH2F2), enabling more eco-friendly processes.Notation and Nomenclature

[0017] The following detailed description and claims utilize a number of abbreviations, symbols, and terms, which are generally well known in the art, and include:

[0018] As used herein, the indefinite article “a” or “an” means one or more.

[0019] As used herein, “about” or “around” or “approximately” in the text or in a claim means ±10% of the value stated.

[0020] As used herein, “room temperature” in the text or in a claim means from approximately 20°C to approximately 25°C.

[0021] The term “substrate” refers to a material or materials on which a process is conducted. The substrate may refer to a wafer having a material or materials on which a process is conducted. The substrates may be any suitable wafer used in semiconductor, photovoltaic, flat panel, or LCD-TFT device manufacturing. The substrate may also have one or more layers of differing materials already deposited upon it from previous manufacturing steps. For example, the wafers may 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, the substrate may be planar or patterned. The substrate may be an organic patterned Iodinated carbon layer film. The substrate may include layers of oxides that are used as dielectric materials in field effect transistor (FET) such as FinFET, MOFSET, GAAFET(Gate all-around FET), Ribbon-FET, Nanosheet, Forksheet FET, Complementary FET (CFET), MEMS, 3D NAND, MIM, DRAM, or FeRam device applications (for example, ZrO2based materials, HfO2based materials, TiO2based materials, rare earth oxide based materials, ternary oxide based materials, etc.) or nitride-based films (for example, TaN, TiN, NbN) that are used as electrodes. The substrate may include layers of alternating oxides (e.g., SiO) and nitrides (e.g., SiN). One of ordinary skill in the art will recognize that the terms “film” or “layer” used herein refer to a thickness of some material laid on or spread over a surfaceand that the surface may be a trench or a line. Throughout the specification and claims, the wafer and any associated layers thereon are referred to as substrates. The substrate may be any solid that has functional groups on its surface that are prone to react with the reactive head of a self-assembled monolayer (SAM), and may include without limitation 3D objects or powders.

[0022] The term “wafer” or “patterned wafer” refers to a wafer that has a stack of films on a substrate, at least the top-most film the stack of the films has topographic features or patterns that have been created in steps prior to etch and the patterned top-most film on is formed for pattern etch.

[0023] The term “processing” as used herein includes patterning, exposure, development, etching, deposition, cleaning, and / or removal of by-products, as required in forming a described structure.

[0024] The term of “etch” or “etching” refers to a series of processes wherein materials are removed from a wafer surface or other surfaces inside a process chamber. Chemical reactions are involved in the processes, which occur after creation of a plasma of the reacting gases or activation of the reacting gases by heat. Physical processes are involved in the processes when in the plasma there is a bias that accelerates ions to bombard the surface and physically sputters away the substrate material. The plasma may be capacitively coupled plasma (CCP), Inductively coupled plasma (ICP), electron cyclotron resonance (ECR) plasma, or a microwave plasma, but is not limited to. Suitable commercially available plasma etching chambers include but are not limited to the Lam Research Dual CCP reactive ion etcher Dielectric etch product family sold under the trademark Flex™ or the Tokyo Electron Tactras™ or Episode™ UL. The non-plasma exposure step may be performed in a different chamber than the plasma exposure step.

[0025] The term “aspect ratio” refers to a ratio of the height of a trench (or aperture) to the width of the trench (or the diameter of the aperture).

[0026] The term “high aspect ratio (HAR)” refers to an aspect ratio ranging from approximately 1 :1 to approximately 500:1 , preferably from approximately 20:1 to approximately 400:1.

[0027] The term “high aspect ratio etching” refers to the formation of a hole pattern in a target film by plasma etching method when aspect ratio of formed hole structures is exceeding value of 5.

[0028] Note that herein, the terms “film”, “layer” and “material” may be used interchangeably. It is understood that a film may correspond to, or related to a layer or a material, and that the layer may refer to the film and the material. Furthermore, one ofordinary skill in the art will recognize that the terms “film” or “layer” or “material” used herein refer to a thickness of some material laid on or spread over a surface and that the surface may range from as large as the entire wafer to as small as a trench or a line.

[0029] Note that herein, the terms “aperture”, “via”, “hole”, “trench”, “feature” and “structure” may be used interchangeably to refer to an opening formed in a semiconductor structure.

[0030] As used herein, the abbreviation "NAND" refers to a "Negative AND" or "Not AND" gate; the abbreviation "2D" refers to 2 dimensional gate structures on a planar substrate; the abbreviation "3D" refers to 3 dimensional or vertical gate structures, wherein the gate structures are stacked in the vertical direction.

[0031] As used herein, the term “etching gas” or “etchant” refers to one or more gaseous material(s) that are performing etching. The source of the material(s) in a container that provides the vapors to do the etching may contain a gas, liquid or solid state of the material(s) and / or combinations thereof. The etching gas and / or etchant may be one gaseous material or chemical. The etching gas and / or etchant may be a mixture of more than one gaseous materials or chemicals.

[0032] Note that herein, the term “QMS” refers to quadrupole mass spectrometry or quadrupole mass spectrometer.

[0033] Note that herein, the terms “etch gas”, “etching gas” and “etchant” may be used interchangeably when the etch gas is in a gaseous state at room temperature and ambient pressure. It is understood that an etch gas may correspond to, or be related to an etchant or an etching gas, and that the etchant may refer to the etch gas and the etching gas.

[0034] The terms “dope” or “doping” is used interchangeably to the process of incorporation of one or more elements into a film through various methods where that element may be chemically bond or physically bond, and the process of intentionally incorporating atoms of different elements into the film composition. The element(s) may be doped interstitial or substitutional within the film.

[0035] The terms “cryogenic etch”, “cryo-etch”, “cryogenic etching”, “cryo-etching”, “low temperature etch”, “low temperature etching”, are used interchangeably to etching processes disclosed herein in which a substrate is cooled to below room temperature.

[0036] The standard abbreviations of the elements from the periodic table of elements are used herein. It should be understood that elements may be referred to by these abbreviation (e.g., 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.).

[0037] The unique CAS registry numbers ( / .e., “CAS”) assigned by the ChemicalAbstract Service are provided to identify the specific molecules disclosed.

[0038] As used herein, the term “hydrofluorocarbon” refers to a saturated or unsaturated function group containing exclusively carbon, fluoride and hydrogen atoms.

[0039] As used herein, the term “fluorocarbon” refers to a saturated or unsaturated function group containing exclusively fluoride and hydrogen atoms.

[0040] As used herein, the term “hydrocarbon” refers to a saturated or unsaturated function group containing exclusively hydrogen and carbon atoms.

[0041] As used herein, the term “GWP” refers to Global Warming Potentials, typically on a 100 year timescale and comparing the global warming potential to CO2.

[0042] As used herein, the term “GWP100” is the GWP over 100 years.

[0043] As used herein, the term “CO2eq” or “CO2e” is CO2 equivalent emission, i.e., the amount of greenhouse gas emissions comparable to CO2 by using the mass of the species being emitted and multiplying by the GWP of the species. This allows the equivalent comparison of the emissions of a process between two different etching gases utilizing the GWP of each molecule.

[0044] As used herein, “CO2emission (CO2e)” or “CO2equivalent emission (CO2eq)” are used interchangeably to refer to the relative global warming impactful emissions.

[0045] 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 range. Any and all ranges recited 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 in between), irrespective of whether the term “inclusively” is used.

[0046] Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. The same applies to the term “implementation.”

[0047] 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 fashion.

[0048] Additionally, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.

[0049] "Comprising" in a claim is an open transitional term that means the subsequently identified claim elements are a nonexclusive listing (i.e. , anything else may be additionally included and remain within the scope of “comprising”). “Comprising” is defined herein as necessarily encompassing the more limited transitional terms "consisting essentially of and “consisting of”; “comprising” may therefore be replaced by "consisting essentially of or “consisting of” and remain within the expressly defined scope of “comprising”.

[0050] “Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actors in the absence of express language in the claim to the contrary.Brief Description of the Drawings

[0051] For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:FIG. 1 is a column graph of a comparison of etching rates between SOF2and SO2F2 applying to common materials used in semiconductor processing, SiO2and SiN, respectively;FIG. 2 is a pie graph of fragments of pure SO2F2 gas;FIG. 3 is a pie graph of fragments of pure CF4SO2 gas; andFIG. 4 is a column graph of XPS of the etched samples etched with SO2F2, CF4SO2 and SOF2with various O2 flow rates.Description of Preferred Embodiments

[0052] Disclosed are methods of cryogenic plasma etching silicon-containing materials in high aspect ratio structures for manufacturing a semiconductor device using an etching gas, thionyl fluoride (SOF2, CAS NO.: 7783-42-8), and / or an etching gas from SOF2family.

[0053] There are benefits of adding SOF2to etching chemistry during cryogenic processes. First, SOF2is a low Global Warming Potential (GWP) and non-carbon precursor. Because SOF2is a non-carbon precursor, it would not clog features, holes or structures etched in a substrate during a plasma etching process due to the non-formation of carbon containing polymer. Next, SOF2is known for its very fast reaction with water, i.e. , SOF2+ H2O — > SO2+ HF (Holleman, Arnold F. (2001), Inorganic Chemistry, p542.). This reaction signifies removal of water and converts it into HF that is a key agent to etch SiO2material at low and / or cryogenic temperature. The reaction of SOF2with water is much faster than the reaction of PF3with water that is expected to significantly enhance the dehydration of the water in an etched hole. In other words, water would be removed from the features, holes or structures in the substrate and at a faster etch rate than currently used PF3 / HF. SO2is also very volatile therefore forming a very volatile byproduct that can be easily removed from the etched structure. Additional generation of HF would increase the etching rate of SiO2and SiN. Lastly, Sulfur is known to act as catalyst for boosting etch rate for silicon material in cryogenic temperatures.

[0054] The disclosed comprises SOF2and SOF2families having the formula: SOmXnand R-SOmXn, where m and n are integers, X is halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, which should accomplish tasks similar to SOF2. Exemplary molecules in these families may include SOF2, SO2F2, SOCI2, SO2CI2, SOI2, CF3-SO2-F, etc.

[0055] The basic reactions for the dehydration of water from etched features or holes are as follows:SOmXn + H2O SO2+ HX HX + SiO2SiX + H2O SO2+ H2O H2SO3

[0056] In this way, the additional generation of HX and Sulfur catalytic effect would boost the etching rate and water may be eliminated from etched features or holes by converting the low volatility H2O into a very high volatility gas, SO2. According to thermodynamic calculations, the reaction of SOF2with water is much more favorable than PF3.

[0057] In some embodiments, under oxidizing conditions, such as with an addition of O2, the reaction is as follows:SOmXn + H2O + O2H2SO4+ HXSimilar to the above reactions without O2, the additional generation of HX and Sulfur catalytic effect would boost the etching rate and water elimination. In addition, SOmXn / HXwould yield a thinner water layer than using PF3 / HF chemistry because i) H2SO4 would reduce the water layer due to its natural dehydration property, ii) H2SO4surface tension of 50 dyne / cm whereas water has surface tension of 72 dyn / cm at 20°C, and H3PO4 has surface tension of 74.6 dyn / cm at 20°C. Thus, under this condition, it is still beneficial to cryogenic etching of SiO2and SiN.

[0058] The disclosed SOF2families of new etching gases may include: a) SOmXn, where m and n are integers, X is a halide such as F, Cl, Br, etc., and a combination of halides if n >2, such as F, Cl, for example, SOFCI, SO2FCI; b) R-SOm-Xn, where m and n are integers, X is a halide such as F, Cl, Br, etc., and X is a combination of halides if n >2, such as F, Cl, for example, SOFCI, SO2FCI and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon.

[0059] Table 1 lists exemplary molecules included in the above disclosed families a) and b):Table 1

[0060] The disclosed cryogenic plasma etching method comprises exposing a substrate to an etching gas SOF2and / or another gas from the SOF2family, preferably SOF2CAS NO.: 7783-42-8, in a reaction chamber during an etching process and / or during a chamber conditioning process.

[0061] The disclosed cryogenic plasma etch method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films comprises: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below 25°C; introducing an etching gas having a general formulaSOmXn; and R-SOmXn, where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, into the reaction chamber; converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture.

[0062] The reaction chamber may be any enclosure or chamber within a device inwhich etching methods take place, such as, without limitation, a reactive ion etching (RIE), a CCP with single or multiple frequency RF sources, an inductively coupled plasma (ICP), a microwave plasma reactors, or other types of etching systems capable of plasma processing, that is, selectively removing a portion of a dielectric film or generating active species or depositing films.

[0063] The reaction chamber is equipped with parallel plate electrodes plasma generators where a high frequency electromagnetic field of 60 MHz is applied to the upper electrode and a 2 MHz one is applied to the lower electrode, when the gap between the electrodes is kept in a range between 10 and 35 mm. Combination of these electric fields allows applying power to the upper electrode within a range of 0-2000 W and to the lower electrode within the range of 1500-7000 W. The plasma may be generated with a RF power ranging from about 25Wto about 100 kW. The plasma may be generated remotely or within the reaction chamber itself. RF frequency of the plasma may range from 100 KHz to 1GHz. The plasma may be pulsed or continuous wave. In some embodiments, the power applied to the chamber may range from 0 to several kW of bias power and hundreds to several thousand kW of source power.

[0064] Temperature and pressure within the reaction chamber are held at conditions suitable for the processing films to react with the activated etching gas SOF2and other gas from the SOF2family. For instance, the pressure in the chamber may be held between approximately 0.1 mTorr and approximately 1000 Torr, preferably between approximately 1 mTorr and approximately 10 Torr, more preferably between approximately 1 mTorr and approximately 1 Torr, even more preferably between approximately 1 mTorr and approximately 30 mTorr, as required by etching parameters. Pressure in the etching chamber during the plasma-etching process may be maintained between 1 and 30 mTorr with introduced the process gas mixture. Likewise, substrate temperature in the reaction chamber may be < 25°C, preferably < - 40°C. Alternatively, the substrate temperature in the reaction chamber may range from approximately -196°C to approximately 300°C; preferably from approximately -196°C to approximately 60°C; more preferably from approximately -196°C to approximately 25°C; even more from approximately -196°C to approximately - 40°C. The substrates may be cooled by a variety of sources including commercially available chillers or other methods such as liquid N2.

[0065] Additional one or more hydrofluorocarbon or fluorocarbon etching gases may be added to the etching gas SOF2and other gas from the SOF2family. 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, C4FW, C5F8,CeF6, C1-C6 CxFyHz molecule (x, y and z are integers), such as C2H5F, C3H7F, C3H2F6, C2HF5, C2H2F2, C6Fi2, C3H2F4, or combinations thereof.

[0066] Other etching gases may be added to the etching gas SOF2and other gas from the SOF2family. The etching gases include H2, SF6, NF3, N2, NH3, Ch, BCI3, BF3, Br2, F2, FNO, FNO3, HBr, HCI, HI, IF5, IF7, HF, HOF, B2H6, and P-containing gases such as PF3, PCI3, PCI5, POCI3, POCI5, PBr3, PH3, POCI3, PF5, POF3, PH3and P(R)3where R is an alkyl or fluorinated alkyl group such as CF3, or the like. Preferably, the etching gas added is HF.

[0067] An inert gas may also be added to the etching gas SOF2and other gas from the SOF2family. The inert gas is selected from Ar, Kr, Xe, Ne, N2, He or combination thereof.

[0068] The disclosed cryogenic plasma etching method further comprises, prior to activating a plasma, sequentially or simultaneously exposing the substrate to a coreactant with or without an additive, wherein the co-reactant is 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 alcohol, ketone, acidic, ester type molecule such as CF3COF, CF3OH, CF3OCF3, (CF3)2C=O, CF3COOH, or combinations thereof.

[0069] The substrate contains silicon-containing materials, such as SiO2, SiN, or Si. One example is alternating layers of SiO and SiN as used in 3D NAND applications. Another example, the silicon containing layer is SiO used in DRAM and 3D DRAM and may include additional layers such as SiN. The silicon-containing film or material comprises a layer of SiaObHcCdNe, where a > 0, b, c, d and e > 0, selected from silicon oxide, silicon nitride, crystalline Si, poly-silicon, 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 poly-silicon (OPOP) films.

[0070] On top of the silicon-containing films or materials is a mask layer or mask material. The mask material may be a layer of amorphous carbon, doped amorphous carbon, spin on carbon (SOC), Si, SiN, Al, AIO, Ti, TiO or other metal and metal oxide masks, or other nitrides such as TiN, with or without dopants.

[0071] The etching gas SOF2and other gas from the SOF2family is supplied in a gas cylinder or other appropriate container at a variety of fill quantities, pressure and specifications. Preferably the material has a low moisture content of <40 ppm, preferably <10 ppm. The etching gas SOF2and other gas from the SOF2family may be purified to remove critical impurities such as chlorine-species or organochlorides, fluorine containingspecies, other sulfur containing species, other fluorocarbons, hydrofluorocarbons, chlorofluorocarbons (CFC’s), impurities from the air (N2, O2, CO2), moisture (H2O), HF other hydrocarbons (CH4, etc.), using distillation, adsorption using molecular sieves, or other commonly known methods in the art. Some impurities may form azeotropes thus other purification methods may need to be employed using chemical means to separate them.

[0072] After etching, the substrate may be warmed up to > - 40°C such that byproducts of the reaction are evaporated away into a vacuum exiting the reaction chamber.

[0073] Not only does the etching gas SOF2and other gas from the SOF2family have a much lower GWP than standard fluorochemical etching gases, it is also expected to produce lower CO2equivalent emissions from the etching process due to the significant reduction in the carbon containing species used in the etching process as compared to standard high aspect ratio etching processes using fluorocarbon and hydrofluorocarbon gases such as C4F8, CHF3, CH2F2, etc. The disclosed cryogenic plasma etch method uses SOF2and other gas from the SOF2family as etching gas to produce apertures, such as channel holes, gate trenches, staircase contacts, capacitor holes, contact holes, contact etch, slit etch, self-aligned contact, self-aligned vias, super vias etc., in silicon-containing films. The resulting apertures may have an aspect ratio ranging from approximately 5:1 to approximately 500:1 , preferably from approximately 20:1 to approximately 400:1. The resulting apertures may have a diameter ranging from approximately 0.1 nm to approximately 500 nm; preferably, ranging from approximately 0.1 nm to approximately 300 nm; more preferably being less than 100 nm. The resulting apertures may have an aspect ratio above 1 :1 , preferably above 5:1 , more preferably above 10:1 , even more preferably above 20:1 . The resulting apertures may have an aspect ratio ranging from 1 :1 to 5: 1. For example, one of ordinary skill in the art will recognize that a channel hole etch produces apertures in the silicon-containing films having an aspect ratio greater than 50:1 .

[0074] The disclosed cryogenic plasma etching method is not limited to the above stated experimental conditions in any way, types of plasma etching tool (e.g., capacity coupled or inductively coupled plasma), process conditions (e.g., pressure, power, temperature, duration of process), process gas mixture, combination and proportion of gases in the process gas mixture, gas flow, workpiece and plasma etching chamber itself may be altered for each process and during the process.

[0075] In summary, the disclosed cryogenic plasma etching methods provide using SOF2and other gas from the SOF2family to enhance control of the deposition profile of the polymer film, as well as to etch silicon oxide and silicon nitride or combination thereofwith high etch rates and selectivity due to enhanced production of HF in the plasma. Additionally, SOF2and other gas from the SOF2family have lower GWP compared to commonly used ones (e.g., CF4, C4F8, CH2F2), enabling more eco-friendly processes.Examples

[0076] A more detailed description of the disclosed methods through examples is provided as follows. However, the disclosed methods is not limited to presented examples in any way and process conditions, process gas mixture, combination and proportion of gases in the gas mixture, workpiece and plasma etching chamber itself may be altered.

[0077] In the following Examples, the primary plasma etching source may be a CCP plasma but may also include other sources such as ICP, microwave, ECR, etc. The plasma may be used in a continuous source or as a pulsed plasma of a certain frequency and duty cycle. The temperature of substrate surface may be cooled down or elevated by a cryogenic chiller, or by liquid N2supply and heating stage. Additional fluorocarbon gases may be added to slightly tune the etching performance. Additional inert gases may be added such as Kr, Xe, Ne, Ne as well as hydrogen source gases such as H2, and hydrocarbons. The mask material may include TiN or other metal nitride materials, SiN, Si, carbon materials, or the like.Example 1: SiO2and SiN etching rate using SOF2and SO2F2

[0078] In a 200mm CCP plasma etch tool, the below experimental conditions as shown in Table 1 were run. From the results as shown in FIG. 1, both SOF2and SO2F2shows similar etching rate of SiO2and SiN. Similar etching rates of SiO2and SiN would be beneficial for etching ONON alternating layers since there is a requirement for same etching rates of SiO2and SiN.Table 1Example 2: QMS of SO2F2and CF4SO2

[0081] The QMS of SO2F2and CF4SO2was obtained by flowing the pure gas into the QMS and the signal collected. FIG. 2 shows the QMS of SO2F2and FIG. 3 shows the QMS of CF4SO2. These QMS shows that both SO2F2and CF4SO2makes many SOmXnspecies that may be beneficial for the reaction with water in the high aspect ratio feature / hole. In addition, the QMS of SOF2makes the following species: SOF, SO, and S with the primary species being the loss of one fluorine to make SOF. The QMS may represent similar species as what would be made inside a plasma process chamber.Example 3. XPS of the etched samples

[0082] FIG. 4 shows XPS results of plasma etched samples etched with gases SO2F2, CF4SO2and SOF2and different flow rates of O2respectively, while other process conditions are kept the same as shown in Example 1 , in which the substrate material was a boron doped carbon which is a common mask material in high aspect ratio etching in memory applications.

[0083] As can be seen, SOF2provides enhanced sulfur composition deposited on the surface as compared to the other molecules SO2F2, CF4SO2at the lowest O2flow rates.

[0084] Cryogenic etching is being applied to a number of new applications in the semiconductor manufacturing processes. The primary application for this would be in the high aspect ratio etching, especially for memory applications such as 3DNAND or DRAM dielectric etching and potentially 3DDRAM. Additionally, cryogenic etching is ideal for applications with highly selective etching as temperature control of which etch reactions produce volatile byproducts can produce nearly infinite selectivity (such as atomic layer etch and stripping processes). As SOF2and SO2F2are looking very promising for high aspect ratio etching with experiments conducted today at room temperature we can imagine it being evaluated for potential use at cryogenic temperature processes. Therefore, the disclosed families of SOmXnand R-SOmXn, where m and n are integers, X is halogen, and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, for lower temperature applications may be critical.

[0085] It will be understood that many additional changes in the details, materials, steps, and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above and / or the attached drawings.

[0086] While embodiments of this invention have been shown and described, modifications thereof may be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments described herein are exemplary only and not limiting. Many variations and modifications of the composition and method are possible and within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims which follow, the scope of which shall include all equivalents of the subject matter of the claims.

Claims

What is claimed is:1 . A cryogenic etching method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below approximately 25°C; introducing an etching gas having a general formulaSOmXn; and R-SOmXn, where m and n are integers, X is a halogen and R is a fluorocarbon, hydrofluorocarbon, or hydrocarbon, into the reaction chamber; converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture.

2. The method of claim 1 , further comprising adding other etching gases such as HF, HOF, H2, SF6, NF3, N2INH3, Cl2, BCI3, BF3, Br2, F2, FNO, FNO3, HBr, HCI, HI, IF5, I F7, B2H6, and P-containing gases such as PF3, PCI3, PCI5, POCI3, POCI5, PBr3, PH3, POCI3, PF5, POF3, PH3and P(R)3where R is an alkyl or fluorinated alkyl group.

3. The method of 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, CI-C6CxFyHz molecule (x, y, and z are integers), C2H5F, C3H7F, C3H2F6, C2HF5, C3H2F4, or combination thereof.

4. The method of 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) selected from COF2, C2O2F2, CxOyFzHm (x, y, z and m are integers) selected from alcohol, ketone, acidic, ester type molecule selected from CF3COF, CF3OH, CF3OCF3, (CF3)2C=O, CF3COOH, or combinations thereof.

5. The method of claim 1 , further comprising adding an inert gas to the etching gas, wherein the inert gas is selected from Ar, Kr, Xe, Ne, N2, He or combination thereof.

6. The method of claim 1 , wherein the etching gas is SOX2, where X is a halogen selected from F, Cl, Br or I.

7. The method of claim 1 , wherein the etching gas is selected from SOF2, SOCI2, or SOCIF.

8. The method of claim 1 , wherein the etching gas is SO2X2, where X is a halogen selected from F, Cl, Br or I.

9. The method of claim 1 , wherein the etching gas is selected from selected from SO2F2, SO2FCI, or SO2CI2.

10. The method of claim 1 , wherein the etching gas is CX4SO2, where X is a halogen selected from F, Cl, Br or I.

11. The method of claim 1 , wherein the etching gas is CF4SO2.

12. The method of any one of claims 1 to 2, 4 to 5 and 7-13, wherein the temperature of the substrate ranges from approximately - 196°C to approximately 300°C.

13. The method of any one of claims 1 to 2, 4 to 5 and 7-13, wherein an aspect ratio of the aperture ranges from approximately 5:1 to approximately 500:1.

14. The method of any one of claims 1 to 2, 4 to 5 and 7-13, wherein an aperture has a diameter ranging from approximately 0.1 nm to approximately 500 nm.

15. The method of any one of claims 1 to 2, 4 to 5 and 7-13, wherein after the aperture is formed, the temperature of the substrate is increased to greater than - 40°C.

16. A cryogenic etching method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising:mounting the substrate in a reaction chamber; cooling the substrate to a temperature below approximately 25°C; introducing an etching gas SOF2, SO2F2orCF4SO2into the reaction chamber; converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture.

17. A cryogenic etching method for forming an aperture by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of the one or more silicon-containing films, the method comprising: mounting the substrate in a reaction chamber; cooling the substrate to a temperature below approximately 25°C; introducing an etching gas SOF2, SO2F2orCF4SO2into the reaction chamber; adding a co-reactant HF into the reaction chamber converting the etching gas to a plasma; and allowing an etching reaction to proceed between the plasma and the one or more silicon-containing films so that the one or more silicon-containing films are selectively etched versus the patterned mask layer to form the aperture.

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