Etching method using oxygen-containing hydrofluorocarbons

Abstract

An etching method for forming apertures 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 includes mounting the substrate in a process chamber; introducing an etching gas containing vapor of an oxygen-containing hydrofluorocarbon into the process chamber; converting the etching gas into a plasma; and allowing an etching reaction to proceed 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 apertures, wherein the oxygen-containing hydrofluorocarbon is a compound represented by the general formula C x H y F z O n (where 2≦x≦13, 1≦y≦15, 1≦z≦21, and 1≦n≦3).

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Patent Application No. 18 / 218,814, filed July 6, 2023, which is a continuation-in-part of U.S. Patent Application No. 18 / 114,134, filed February 24, 2023, the contents of which are incorporated herein by reference.

[0002] The present invention relates to a plasma etching method using an oxygen-containing hydrofluorocarbon-based plasma etching chemistry as an etchant for anisotropic etching of SiO, SiN, stacks of alternating SiO and SiN films, and other Si-containing films with high etch rates, high selectivity to mask materials, and forming well-defined profile patterns in high aspect ratio structures, and in particular to a plasma etching method using an oxygen-containing hydrofluorocarbon-based plasma etching chemistry as an etchant for anisotropic etching of SiO, SiN, stacks of alternating SiO and SiN films, and other Si-containing films with high etch rates, high selectivity to mask materials, and forming well-defined profile patterns in high aspect ratio structures. x H y F z O n wherein 2≦x≦10, 1≦y≦15, 1≦z≦21, and 1≦n≦3, preferably wherein at least one oxygen atom is incorporated into the hydrofluorocarbon via an ether or carbonyl group. [Background technology]

[0003] Improvements in terms of control of deposited polymer film profile to fine-etch well-defined profile patterns, high etch rates of silicon-containing (e.g., SiO2, Si3N4, or alternating combinations of SiO2 and Si3N4) films, and high selectivity to mask materials (e.g., amorphous carbon, amorphous silicon, doped amorphous carbon, or amorphous silicon) are expected in high aspect ratio contact and channel etching for applications such as 3D NAND and DRAM memory fabrication.

[0004] Recently, silicon and silicon-based dielectrics have become key components of all semiconductor devices. The limitations of transistor scaling, along with the constant need for significant increases in memory capacity, have led to a shift in the semiconductor industry from 2D-type structures to 3D integration. The production of semiconductor devices with vertical structures, such as 3D NAND or DRAM, brings new manufacturing challenges. One of the major issues associated with the fabrication of 3D semiconductor devices (such as 3D NAND), is the increasing height of the elements, which necessitates etching of structures (apertures, holes, pillars, etc.) in the dielectric with a high aspect ratio (the ratio of the structure's height to its width). More specifically, the 3D NAND fabrication process requires deep etching of alternating layers of silicon oxide or silicon nitride and silicon oxide with well-defined profiles, and soft landing on the underlying (bottom) layer, which is a very challenging process even for state-of-the-art devices. Therefore, the etching process should feature high silicon oxide and silicon nitride etching rates to maintain high production yields, while the etching rates of the hard mask and bottom landing layer should be kept as low as possible to avoid damage and various defects. Controlling the etched void profile (where thin lateral size and straight vertical profile are typically desired) has recently become one of the most important factors and challenges in the fabrication of complex 3D semiconductor structures. Maintaining a well-defined profile requires minimizing negative processing effects and defects, such as warping, twisting, or other pattern distortions. These defects primarily stem from insufficient control of the polymer film deposited during the etching process to protect portions of the structure not intended to be etched (e.g., the sidewalls of the void or mask). Portions of the sidewall with an insufficiently deposited polymer-based protective film can deform during the high-aspect-area etching process, leading to the formation of the aforementioned defects. Therefore, fine-tuning the etching process, including precise control of polymer passivation conformality, is necessary to ensure good protection of the sidewall while avoiding mask blockage or etch stop at the bottom of the void during the etching process.

[0005] Although there is a wealth of prior art for etching SiO2 or Si3N4 with fluorocarbon gases, most of the etching gas mixtures disclosed in the prior art contain molecular O2 gas. For example, U.S. Patent No. 6,069,092 to Imai et al. discloses dry etching using fluorocarbon gas mixed with an inert gas and oxygen. U.S. Patent No. 5,626,775 A to Roberts et al. discloses etching silicon dioxide or silicon nitride using trifluoroacetic acid and its oxygen-containing derivatives, where the etching chemistry is mixed with oxygen. U.S. Patent No. 7,153,779 B2 to Trapp et al. discloses etching silicon oxide layers for high aspect ratio contact applications using organic fluorocarbons with nitrogen-containing gases. U.S. Patent No. 6,540,930 B2 to Kesari et al. discloses the use of perfluoroketones having 4 to 7 carbon atoms mixed with oxygen to remove deposits and etch dielectrics and metals in a vapor reactor (a non-plasma process).

[0006] Various oxygen-containing compounds have been used as etching gases to etch SiO2 or Si3N4.

[0007] U.S. Patent Application Publication No. 2019 / 0345385 A1 to Oomori et al. discloses a CF3-C etching process for etching silicon-based materials. x H y F z O (where x=2 or 3; y=1, 2, 3, 4 or 5 and z=2x-1-y) with a three-membered ring containing one oxygen x H y F z Discloses the use of O.

[0008] Japanese Patent Publication No. 2000038580 to Kumagai et al. discloses the use of CF3CFHOCF2H for etching silicon-based materials. The patent is pending and the target molecule is of a specific formula and structure.

[0009] Patent No. 6,773,110 to Matsuura et al. discloses the use of R-CF-O-CH2-R (a methyl ether-based fluorocarbon) to etch silicon oxide and prevent neck growth (pattern diameter) in SiN masks.

[0010] WO 2009019219 A2 to Uenveren et al. discloses the application of O-containing fluorocarbons and hydrofluorocarbons used as etching gases for semiconductor etching or chamber cleaning, where at least one O-containing fluorocarbon and hydrofluorocarbon is selected.

[0011] U.S. Patent No. 6,514,425 B1 to Sekiya et al. discloses a dry etching method for SiO2 using C3HF7O, C4HF9O, and C2-6 ether-containing molecules. U.S. Patent Application Publication No. 20170243756 A1 to Matsuura et al. discloses hydrofluoroether C m F 2m+1 -O-CH2-R (wherein R is a hydrogen atom or C n F 2n+1 where m and n are positive integers satisfying 1≦m≦3 and 3≦(m+n)≦4. C4H3F7O is disclosed in the examples.

[0012] U.S. Patent No. 7,744,769 B2 to Mouri et al. discloses dry (thermal) etching of SiO using OF bond-containing hypofluorites, such as CF3OF, CF2(OF)2, CF3CF2OF, CH3COOF, (CF3)3COF, CF2HCF2OF, (CF3CF2)(CF3)2COF, CH3OF, CFH2OF, CF2HOF, CF3CF2CF2OF, and (CF3)2CFOF.

[0013] U.S. Patent Application Publication No. 2002 / 0096487 A1 to Demmin et al. discloses a plasma etching and chamber cleaning method using C3H2F2O2 and various carbonyl group-containing molecules having specific structures defined by the formula: U.S. Patent Application Publication No. 2005 / 0096238 A1 to Ryuichiro et al. v H x F y O z (wherein v is an integer of 1 to 5, x is selected from 0 and an integer of 1 to 3, y is an integer of 1 to 12, and z is selected from 0 and 1)

[0014] U.S. Patent Application Publication No. 20080274334A1 to Sekiya et al. discloses plasma etching of SiO2 and other semiconductor materials using hydrofluorocarbons containing ether groups with a number of C atoms in the range of 4 to 6 and an (F / C) ratio of 1.9 or less.

[0015] U.S. Patent No. 6,242,359 B1 to M Ashutosh discloses plasma etching of metals using oxygen-containing compounds CH2F2O, CHF3O, C3H2F9O, C2H2F4O2.

[0016] Kim et al. (2018 ECS J. Solid State Sci. Technol. 7 Q218) reported that heptafluoropropyl methyl ether (HFE-347mcc3, C4H3F7O) and perfluoropropyl vinyl ether (PPVE, CF2=CFOCF2CF2CF3, C5F 10 discloses a method for plasma etching of SiO2 using SiO2.

[0017] Kim et al. (Applied Surface Science Volume 508, 1 April 2020, 144787) disclose SiO2 etching in an inductively coupled plasma using heptafluoroisopropyl methyl ether (C4H3F7O) and 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (C4H3F7O).

[0018] Kim et al. (Journal of Vacuum Science & Technology A 38, 022606 (2020)) discloses atomic layer etching of SiO2 and Si3N4 using heptafluoropropyl methyl ether (C4H3F7O).

[0019] U.S. Patent No. 10,424,489 B2 to Matsuura Go discloses a compound having the following structure: [ka] (wherein R1 is a hydrogen atom, a fluorine atom, or a fluoroalkyl group C x F 2x+1 R2 represents a hydrogen atom, a fluorine atom, or a fluoroalkyl group C y F 2y+1 R3 represents a hydrogen atom, a fluorine atom, or a fluoroalkyl group C z F 2z+1where x, y, and z are integers at least 0 and not more than 3, respectively, satisfying 1≦x+y+z≦3, and R1, R2, and R3 may be the same or different. Examples of hydrofluoroether gases represented by the above chemical structural formula include CF3-O-CH2C2F5, CF3-O-CH2-n-C3F7, CF3-O-CH2-i-C3F7, C2F5-O-CH2-CF3, C2F5-O-CH2-C2F5, n-C3F7-O-CH3, and i-C3F7-O-CH3 gases.

[0020] European Patent Application Publication No. 1498941A2 to Ji et al. discloses a compound of formula C x F y O z R q wherein R is a hydrogen atom, a hydrocarbyl group having a number of carbon atoms in the range of 1 to 5, a halocarbyl group having a number of carbon atoms in the range of 1 to 5, or a halohydrocarbyl group having a number of carbon atoms in the range of 1 to 5; x is a number in the range of 2 to 10; y is a number less than 2x-q; z is a number in the range of 1 to 2; and q is a number in the range of 0 to 1, wherein the ratio of F atoms to C atoms is less than 2, with the proviso that when x is a number in the range of 3 to 10, then y is a number less than 2x-q, z is 1, and q is 0, wherein the mixture further comprises an oxidizer, and wherein the volume ratio of oxidizer to unsaturated oxidized fluorocarbon is in the range of 0:1 to 1.0:1.

[0021] WO 20221009553 A1 to M Kazuma discloses a method for plasma etching of Si3N4 using a fluorine compound having three or fewer carbon atoms and at least one of a carbon-oxygen double bond (carbonyl group) and an ether bond in the molecule.

[0022] WO 1999034429A1 to Demmin et al. discloses F-CO-[(CR,R2) m-CO] n -F and F-CO-R-CO-F (wherein m=0, 1, 2, 3, 4, or 5; n=1, R1=R2=H or F or C) x H y F z (x=1 or 2, y+z=2x+1), R3=“CR4=(double bond)CR5” or “R6R7” or “C=C” or “C≡C” (R 4~7 = H or F or C x H y F z and x=1 or 2, y+z=2x+1).

[0023] U.S. Patent Application Publication No. 20170243756A1 to Matsuura et al. discloses a compound of formula C m F 2m+1 -O-CH2-R (wherein R is a hydrogen atom or C n F 2n+1 (wherein 1≦m≦3, 3≦(m+n)≦4))

[0024] U.S. Patent Application Publication No. 2005 / 0096238A1 to Isaki et al. discloses a compound of formula C v H x F y O z (wherein v is an integer of 1 to 5, x is selected from 0 and an integer of 1 to 3, y is an integer of 1 to 12, and z is selected from 0 and 1)

[0025] WO 2005 / 117082 A1 to Sekiya et al. disclosed a dry etching gas containing a C4-C6 fluorine compound having an ether bond or a carbonyl group with an F / C ratio of 1.9 or less, provided that the compound is neither a fluorine compound having one cyclic ether bond and one carbon-carbon double bond nor a saturated fluorine compound having one carbonyl group.

[0026] U.S. Patent Application Publication No. 2003 / 0019841 A1 to Kesari et al. discloses methods for using perfluoroketones as steam reactor cleaning gases, etching gases, and doping gases, including reactant gases containing perfluoroketones having 4 to 7 carbon atoms for removing unwanted deposits that build up in steam reactors, etching dielectric and metallic materials in steam reactors, and doping materials in steam reactors.

[0027] U.S. Patent Application Publication No. 2003 / 0001134 A1 to Sekiya et al. discloses a cleaning gas and etching gas containing at least one compound selected from the group consisting of FCOF, CFOCOF, CFOCFOCOF, CFCOF, CFCOF, or CF(COF)2, a specific amount of O2, and optionally other gases. The chamber cleaning gas and silicon-containing film etching gas of the present invention have a low global warming potential and produce little or no substances in the exhaust gas, such as CF4, which are recognized as being harmful to the environment and contributing to global warming.

[0028] WO2022009553 A1 discloses the etching selectivity of SiN versus amorphous carbon (aC), photoresist, and SiO2 using an etching gas containing a fluorine compound having three or fewer carbon atoms and at least one of a carbon-oxygen double bond (C=O) and / or an ether bond (C-O-C). Only COF2 appears in the examples.

[0029] U.S. Patent Application Publication No. 2017 / 0243756 to Matsuura discloses the use of CF3-CHF-O-CHF2 as an etching gas in Comparative Example 7 in paragraph

[0075] . However, CF3-CHF-O-CHF2 shows that "the selectivity ratio with respect to silicon nitride and photoresist was low" (see Matsuura, paragraph

[0082] ).

[0030] Although it is possible to etch high aspect ratio structures using mixtures of common fluorocarbon (CF4, C4F6, C4F8, C5F8) and hydrofluorocarbon (CH2F2, CHF3, CH3F, and C5HF7) vapors, there remains a need to improve the selectivity to the mask, the control of the shape of the etched structures, and to increase the etch rate, which becomes more critical during the processing of high aspect ratio structures (e.g., aspect ratios in the range of 1 to 1000) with reduced lateral dimensions used in advanced semiconductor devices. Summary of the Invention [Problem to be solved by the invention]

[0031] It is therefore an object of the present disclosure to provide a plasma etching method that can improve selectivity to the mask, preserve the critical dimensions of the pattern, and provide better control over the shape of the etched high aspect ratio structures while maintaining a high etch rate. [Means for solving the problem]

[0032] 1. An etching method for forming apertures 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 a substrate within a processing chamber; introducing an etching gas containing an oxygen-containing hydrofluorocarbon vapor into the process chamber; converting the etching gas into a plasma; allowing an etching reaction to proceed 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 apertures; The disclosed etching method comprises the following features: The oxygen-containing hydrofluorocarbon is represented by the general formula C x H y F z O n (where 2≦x≦13, 1≦y≦15, 1≦z≦21, 1≦n≦3); The oxygen-containing hydrofluorocarbon contains at least one oxygen atom in an ether group; The oxygen-containing hydrofluorocarbon contains at least one oxygen atom in a carbonyl group; The oxygen-containing hydrofluorocarbon has the formula: R1-CO-O-CH2-R1, R2-CH2-O-CH2-R2 or R3-CHF-O-CF2-R1 (Wherein R1 is H, F, C x H 2x+2-z F z or C x F 2x+2 and R2 is H, C x H 2x+2-z F z or C x F 2x+2 and R3 is F, C x H 2x+2-z F z or C x F 2x+2 where 2≦x≦3 and 1≦z≦3. having at least one ether group represented by one of the following: The oxygen-containing hydrofluorocarbon has the formula: R1-CO-O-CH2-R1 (Wherein R1 is H, F, C x H 2x+2-z F z or C x F 2x+2 where 2≦x≦3 and 1≦z≦3. having at least one ether group represented by the formula: The oxygen-containing hydrofluorocarbon has the formula: R2-CH2-O-CH2-R2 (Wherein R2 is H, Cx H 2x+2-z F z or C x F 2x+2 where 2≦x≦3 and 1≦z≦3; having at least one ether group represented by the formula: The oxygen-containing hydrofluorocarbon has the formula: R3-CHF-O-CF2-R1 (Wherein R1 is H, F, C x H 2x+2-z F z or C x F 2x+2 and R3 is F, C x H 2x+2-z F z or C x F 2x+2 where 2≦x≦3 and 1≦z≦3. having at least one ether group represented by the formula: Oxygen-containing hydrofluorocarbons include C4H4F6O, C4H2F6O2, C3H2F6O, C2H2F4O, C2HF3O, C3H5F3O, C2H4F2O, C4H6F4O, C5H4F8O, and C5HF 11 O, C2H3F3O, or an isomer thereof; · The oxygen-containing hydrofluorocarbon is C4H4F6O, CAS number 57041-67-5; · The oxygen-containing hydrofluorocarbon is C4H4F6O, CAS number 84011-06-3; · The oxygen-containing hydrofluorocarbon is C4H4F6O, CAS number 920-66-1; The oxygen-containing hydrofluorocarbon is C4H4F6O or an isomer thereof; · The oxygen-containing hydrofluorocarbon is C4H4F6O, CAS number 382-34-3; · The oxygen-containing hydrofluorocarbon is C4H4F6O, CAS number 333-36-8; The oxygen-containing hydrofluorocarbon is C4H2F6O2 or its isomers; · The oxygen-containing hydrofluorocarbon is C4H2F6O2, CAS number 407-38-5; Etching gases include CF4, C2F6, C3F6, C4F6, C4F8, C5F8, and C5F 10 , C6F 12 , C7F 14 , C8F 16 , CH2F2, CH3F, CHF3, C5HF7, C3H2F6, C3H4F2, C3F2H4, C4H2F6, C4H3F7, C3HF4N, CF3I, C3F7I, C4F9I, C4H9F3Si, C5H9F5Si, or combinations thereof; the etching gas further comprises an oxidizing gas selected from O2, O3, CO, CO2, SO, SO2, FNO, N2, NO, N2O, NO2, H2O, COS, or a combination thereof; The etching gas further comprises an inert gas selected from He, Ar, Xe, Kr, or Ne; the etching gas further comprises an additional gas selected from H2, SF6, NF3, N2, NH3, Cl2, BCl3, Br2, F2, HBr, HCl, PF3, or a combination thereof; The one or more silicon-containing films are selected from silicon oxide, silicon nitride, crystalline Si, poly-silicon, polycrystalline silicon, amorphous silicon, low-k SiCOH, SiOCN, SiC, SiON, Si a O b H c C d N e (where a>0, b, c, d, and e≧0), or layers of alternating silicon oxide and silicon nitride (ONON) films or alternating silicon oxide and poly-silicon (OPOP) films; The silicon-containing film is a silicon oxide film, a silicon nitride film, or a stack of alternating silicon oxide and silicon nitride films; The aperture aspect ratio is in the range of approximately 5:1 to approximately 500:1; The aperture aspect ratio is in the range of approximately 20:1 to approximately 400:1; · The aspect ratio of the aperture has an aspect ratio greater than 50:1; ·Aperture aspect ratio is greater than 5; ·Aperture aspect ratio is greater than 10; ·Aperture aspect ratio is greater than 20; the aperture has a diameter in the range of approximately 5 nm to approximately 500 nm; the aperture has a diameter of less than 100 nm; The selectivity of silicon oxide to silicon nitride in the ONON film layer is in the range of 1:20 to 20:1; The selectivity of silicon oxide to silicon nitride in the ONON film layer is in the range of 1:10 to 10:1; The selectivity of silicon oxide film to silicon nitride film in the ONON film layer is 1:5~5 :1 range; The selectivity of the silicon oxide film to the silicon nitride film in the ONON film layer is in the range of 1:2 to 2:1; and The selectivity of silicon oxide to silicon nitride in the ONON film layer is close to 1. may include one or more of:

[0033] 1. An etching method for forming apertures by selectively etching a silicon oxide film in a substrate using a patterned mask layer deposited on top of the silicon oxide film, the method comprising: Mounting a substrate within a processing chamber; introducing an etching gas containing oxygen-containing hydrofluorocarbon C3H2F6O vapor into the process chamber; converting the etching gas into a plasma; causing an etching reaction to proceed between the plasma and the silicon oxide film such that the silicon oxide film is selectively etched relative to the patterned mask layer to form apertures; The disclosed etching method includes the following features: · Oxygen-containing hydrofluorocarbon C3H2F6O is C3H2F6O, CAS number 57041-67-5; · Oxygen-containing hydrofluorocarbon C3H2F6O is C3H2F6O, CAS number 84011-06-3; · Oxygen-containing hydrofluorocarbon C3H2F6O is C3H2F6O, CAS number 920-66-1; Etching gases include CF4, C2F6, C3F6, C4F6, C4F8, C5F8, and C5F 10 , C6F 12 , C7F 14 , C8F 16 , CH2F2, CH3F, CHF3, C5HF7, C3H2F6, C3H4F2, C3F2H4, C4H2F6, C4H3F7, C3HF4N, CF3I, C3F7I, C4F9I, C4H9F3Si, C5H9F5Si, or combinations thereof; the etching gas further comprises an oxidizing gas selected from O2, O3, CO, CO2, SO, SO2, FNO, N2, NO, N2O, NO2, H2O, COS, or a combination thereof; The etching gas further comprises an inert gas selected from He, Ar, Xe, Kr, or Ne; the etching gas further comprises an additional gas selected from H2, SF6, NF3, N2, NH3, Cl2, BCl3, Br2, F2, HBr, HCl, PF3, or a combination thereof; The aperture aspect ratio is in the range of approximately 5:1 to approximately 500:1; The aperture aspect ratio is in the range of approximately 20:1 to approximately 400:1; · The aspect ratio of the aperture has an aspect ratio greater than 50:1; ·Aperture aspect ratio is greater than 5; ·Aperture aspect ratio is greater than 10; ·Aperture aspect ratio is greater than 20; The aperture has a diameter in the range of about 5 nm to about 500 nm; and The aperture has a diameter of less than 100 nm. may include one or more of:

[0034] The high-aspect-ratio etching process allows for etching of target material in unmasked workpieces preferentially in the vertical direction, resulting in the formation of vertical apertures with high aspect ratios in the target material. Preferential vertical etching to form etched structures is achieved by balancing the deposition and etching processes. Isotropic deposition of polymer over the entire workpiece allows for passivation to form on the sidewalls of the etched apertures, preventing lateral etching. Meanwhile, the etching process consists of two components: anisotropic directional etching by ion bombardment and isotropic chemical-based etching by reactive chemical species. In this case, the sidewall passivation of the etched structures, as well as the mask, prevents lateral etching and mask erosion, which allows for directional vertical etching of high-aspect-ratio structures that maintain near-initial lateral dimensions. Directional etching is achieved by directional ion bombardment (top-to-bottom) of passivation polymers at the bottom of the structure being etched, avoiding bombardment of polymers on the sidewalls, which damages the polymer on the bottom, causing the chemical reaction to proceed preferentially at the bottom of the structure, resulting in the formation of volatile by-products and preferential material removal at the bottom surface. Commonly used fluorocarbon and hydrofluorocarbon gases allow for relatively high anisotropic etch rates to be achieved, where most of the technical problems stem from poor control of polymer growth along the sidewalls and poor selectivity to the mask, resulting in profile distortion. Furthermore, for future generations of semiconductor devices, increasing aspect ratios result in significant losses in etch rate when common etching gas mixtures are used, creating a need for the development of novel etch chemistries that can maintain high etch rates with further increases in aspect ratio. The present invention aims to improve profile control while maintaining high etch rates in high aspect ratio structures.The present invention concludes that the addition of oxygen-containing hydrofluorocarbons to a process gas mixture can significantly enhance the etch rate of SiO2, SiN, and other Si-containing materials and improve target material to mask selectivity.

[0035] Specifically, the present invention discloses a plasma etching method comprising plasma etching of a workpiece containing a dielectric (e.g., silicon oxide) as a process target film and a non-process target film (e.g., amorphous carbon mask) using a gas mixture consisting of, but not limited to, vapor of one oxygen-containing hydrofluorocarbon compound, optionally one fluorocarbon and / or hydrofluorocarbon, optionally an inert gas, and optionally an oxidizing gas as a process gas mixture to form high aspect ratio structures.

[0036] In the disclosed plasma etching method, the plasma processing gas is a mixture of vapor of an oxygen-containing hydrofluorocarbon compound, optionally an inert gas, optionally an oxidizing gas, and optionally a fluorocarbon and / or hydrofluorocarbon. Further, the fluorocarbon gas preferably has the formula CF4, C2F6, C3F6, C4F6, C4F8, C5F8, C5F to improve etching of the target processed thin film dielectric and / or improve selectivity to non-targeted thin films. 10 , C6F 12 , C7F 12 , C8F 16 The hydrofluorocarbon is preferably a gas of a compound represented by the formula CH2F2, CH3F, CHF3, C5HF7, C3H2F6, C3F2H4, C4H2F6, C4H3F7, C3HF4N to improve etching of the target processed thin film dielectric and / or improve selectivity to non-target thin films. The oxygen-containing hydrofluorocarbon compound in the disclosed method is a gas of a compound represented by the formula C x H y F z O n(wherein 2≦x≦10, 1≦y≦15, 1≦z≦21, 1≦n≦3), and preferably at least one oxygen atom is incorporated into the molecule by an ether group or by a carbonyl group. More preferentially, the disclosed oxygen-containing hydrofluorocarbon compounds have the formula R1-CO-O-CH2-R1, R2-CH2-O-CH2-R2 or R3-CHF-O-CF2-R1 (wherein R1 is H, F, C x H 2x+2-z F z or C x F 2x+2 and R2 is H, C x H 2x+2-z F z or C x F 2x+2 and R3 is F, C x H 2x+2-z F z or C x F 2x+2 where 2≦x≦3 and 1≦z≦3. More preferentially, the disclosed oxygen-containing hydrofluorocarbons may contain at least one ether group, including their isomers, C4H4F6O, C4H2F6O2, C3H2F6O, C2H2F4O, C2HF3O, C3H5F3O, C2H4F2O, C4H6F4O, C5H4F8O, C5HF 11 O, C2H3F3O, and combinations thereof. More preferentially, the disclosed oxygen-containing hydrofluorocarbons are selected from C3H2F6O, C4H4F6O, C4H2F6O2 or isomers thereof.

[0037] Notation and Nomenclature The following detailed description and claims utilize a number of abbreviations, symbols, and terms that are commonly known in the art, including the following:

[0038] As used herein, the indefinite article "a" or "an" means one or more.

[0039] As used herein, "about" or "around" or "approximately" in the text or claims means ±10% of the stated value.

[0040] As used herein, "room temperature" in the text and claims means approximately 20°C to approximately 25°C.

[0041] The term "substrate" refers to the material or materials on which a process is performed. A substrate may refer to a wafer having the material or materials on which a process is performed. A substrate may be any suitable wafer used in semiconductor, solar cell, flat panel, or LCD-TFT device manufacturing. A substrate may also have one or more layers of different materials already deposited thereon from a previous manufacturing step. For example, a wafer may include a silicon layer (including but not limited to, crystalline, amorphous, porous, etc.), a silicon-containing layer (including but not limited to, SiO2, SiN, SiON, SiCOH, etc.), a metal or metal-containing layer (including but not limited to, copper, cobalt, ruthenium, tungsten, platinum, palladium, nickel, ruthenium, gold, etc.), or a combination thereof. Furthermore, a substrate may be flat or patterned. The substrate may be an organic patterned iodine-treated carbon layer film. The substrate may include a layer of oxide used as a dielectric or a nitride-based film (e.g., TaN, TiN, NbN) used as an electrode in a field effect transistor (FET), such as a FinFET, MOFSET, Gate all-around FET (GAAFET), Ribbon-FET, Nanosheet, Forksheet FET, Complementary FET (CFET), MEMS, 3D NAND, MIM, DRAM, or FeRAM device application (e.g., ZrO2-based materials, HfO2-based materials, TiO2-based materials, rare earth oxide-based materials, ternary oxide-based materials, etc.). The substrate may include alternating oxide (e.g., SiO2) and nitride (e.g., SiN) layers. Those skilled in the art will recognize that the term "film" or "layer" as used herein refers to a material of a certain thickness deposited on or spread over a surface, and that the surface may be a groove or a line. Throughout this specification and claims, the wafer and any associated layer thereon are referred to as the substrate. The substrate can be any solid having functional groups on its surface that tend to react with the reactive top of the self-assembled monolayer (SAM), and can include, without limitation, a 3D object or a powder.

[0042] The term "wafer" or "patterned wafer" refers to a wafer having a stack of films on a substrate, where at least the top film of the stack of films has topographical features or patterns created in a pre-etch step, and the patterned top film is configured for pattern etching.

[0043] The term "processing" as used herein includes patterning, exposing, developing, etching, depositing, cleaning, and / or removing by-products as required to form the described structures.

[0044] The terms "depositing" or "deposition" refer to a series of processes in which materials at the atomic or molecular level are deposited on a wafer surface or substrate from a gaseous state (vapor) to a solid state as a thin layer. This process involves chemical reactions that occur after generating a plasma of reactive gases or activating reactive gases with heat. 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 Dual CCP Reactive Ion Etcher, the dielectric etching product line sold under the trademarks Flex™, Tokyo Electron Tactras™, or Episode™ UL. Non-plasma exposure steps may be performed in a different chamber from the plasma exposure step.

[0045] The term "aspect ratio" refers to the ratio of the groove (or aperture) height to the groove width (or aperture diameter).

[0046] 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.

[0047] The term "high aspect ratio etching" refers to the formation of pore patterns in a target film by a plasma etching method when the aspect ratio of the pore structures formed exceeds a value of five.

[0048] It should be noted that the terms "film" and "layer" can be used interchangeably herein. It is understood that a film can correspond to or relate to a layer, and a layer can refer to a film. Furthermore, those skilled in the art will recognize that the term "film" or "layer" as used herein refers to a material of some thickness placed on or spread over a surface, and that the surface can range from as large as an entire wafer to as small as a groove or line.

[0049] It should be noted that, as used herein, the terms "aperture," "via," "hole," "trench," and "structure" may be used interchangeably to refer to openings formed in semiconductor structures.

[0050] As used herein, the abbreviation "NAND" refers to a "negative AND" or "non-AND" gate; the abbreviation "2D" refers to a two-dimensional gate structure on a planar substrate; and the abbreviation "3D" refers to a three-dimensional or vertical gate structure, where the gate structures are stacked vertically.

[0051] It should be noted that, as used herein, the terms "etching gas" and "etchant" may be used interchangeably when the etching gas is in a gaseous state at room and ambient temperatures. It is understood that an etching gas may correspond to or be related to an etchant, and that an etchant may refer to an etching gas.

[0052] The terms "doping" or "doping" are used interchangeably to refer to the process of incorporating one or more elements into a film by various methods, where the elements may be chemically or physically bonded, and the process intentionally incorporates atoms of different elements into the film composition. Elements may be doped interstitially or substitutionally into the film.

[0053] Standard abbreviations for elements from the periodic table of the elements are used herein, and it should be understood that elements may be referred to by these abbreviations (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.).

[0054] Unique CAS Registry Numbers assigned by the Chemical Abstract Service (i.e., "CAS") are provided to identify the specific molecules disclosed.

[0055] As used herein, the term "hydrofluorocarbon" refers to a saturated or unsaturated functional group containing exclusively carbon, fluorine, and hydrogen atoms.

[0056] As used herein, the term "fluorocarbon" refers to saturated or unsaturated functional groups containing exclusively fluorine and hydrogen atoms.

[0057] As used herein, the term "alkyl group" refers to a saturated functional group containing exclusively carbon and hydrogen atoms. An alkyl group is a type of hydrocarbon. Furthermore, the term "alkyl group" refers to a linear, branched, or cyclic alkyl group. Examples of linear alkyl groups include, without limitation, methyl, ethyl, propyl, butyl, etc. Examples of branched alkyl groups include, without limitation, t-butyl. Examples of cyclic alkyl groups include, without limitation, cyclopropyl, cyclopentyl, cyclohexyl, etc.

[0058] Ranges may be expressed herein as from about one particular value and / or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and / or to the other particular value, along with all combinations within said ranges. Any and all ranges recited herein include their endpoints (i.e., x=1 to 4 or a range of x from 1 to 4 includes x=1, x=4, and any number therebetween).

[0059] References herein to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of the invention. Appearances of the phrase "in one embodiment" in various places in this specification do not necessarily all refer to the same embodiment, nor do separate or alternative embodiments necessarily exclude each other. The same applies to the term "implementation."

[0060] As used in this application, the word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete manner.

[0061] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise specified, or is clear from the context. "X uses A or B" is intended to mean any of the natural inclusive permutations. That is, if X uses A, then X uses B; or X uses both A and B, then "X uses A or B" would be satisfied under any of the foregoing examples. Additionally, the articles "a" and "an," as used in this application and the appended claims, should generally be construed to mean "one or more" unless otherwise specified or clear from the context to be directed to the singular form.

[0062] In the claims, "comprising" is an open transitional term meaning that the claim elements identified thereafter are non-exclusive (i.e., anything else may also be included and remain within the scope of "comprising"). "Comprising" is defined herein as not necessarily including the more restrictive transitional terms "consisting essentially of" and "consisting of"; "comprising" may therefore be replaced by "consisting essentially of" or "consisting" while remaining within the expressly defined scope of "comprising."

[0063] "Providing" in the claims is defined to mean giving, supplying, making available, or preparing something. A step may be performed by any party unless there is express language in the claim to the contrary.

[0064] 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 similar reference numerals and in which: [Brief explanation of the drawings]

[0065] [Figure 1A] FIG. 1A is a cross-sectional view of a block diagram illustrating an exemplary initial structure of a workpiece used in the disclosed plasma etching process. [Figure 1B] FIG. 1B is a cross-sectional view of a block diagram illustrating an exemplary etched profile of a workpiece. [Figure 2] Figure 2 summarizes the fragments and molecules present in the plasma afterglow recorded by quadrupole mass spectrometry (QMS). [Figure 3] FIG. 3 shows the resulting etch rate as a function of the aspect ratio of the structure being etched. [Figure 4A] FIG. 4A shows the resulting etch rates of SiO and SiN as well as the resulting selectivity of SiO to SiN as a function of O flow rate in Example 6. [Figure 4B] FIG. 4B shows the resulting etch rates of SiO and SiN as well as the resulting selectivity of SiO to SiN as a function of O flow rate in Example 7. [Figure 4C] FIG. 4C shows the resulting etch rates of SiO and SiN as well as the resulting selectivity of SiO to SiN as a function of O flow rate in Example 8. [Figure 4D] FIG. 4D shows the resulting etch rates of SiO and SiN as well as the resulting selectivity of SiO to SiN as a function of O flow rate for Example 9. [Figure 4E] FIG. 4E shows the resulting etch rates of SiO and SiN as well as the resulting selectivity of SiO to SiN as a function of O flow rate for Example 10. DETAILED DESCRIPTION OF THE INVENTION

[0066] A plasma etching method is disclosed that uses a novel oxygen-containing hydrofluorocarbon-based plasma etching chemistry as an etchant for anisotropic etching of silicon oxide, silicon nitride, alternating silicon oxide and silicon nitride film stacks, and other Si-containing films with high etch rate (ER), high selectivity to mask materials (e.g., amorphous carbon or doped amorphous carbon), and forming well-defined profile patterns with high aspect ratio structures. The disclosed plasma etching method can be used in high aspect ratio etching for, but not limited to, the fabrication of 3D NAND structures, contact holes, DRAM capacitors, etc. Disclosed is a plasma etching method for processing workpieces including one or more target etching process films (e.g., silicon oxide, silicon nitride, or combinations thereof) and non-process target films (e.g., amorphous carbon, amorphous silicon, doped amorphous carbon, doped amorphous silicon, metals) when a process gas mixture including at least one oxygen-containing hydrofluorocarbon (e.g., C4H4F6O, C4H2F6O2), optionally at least one inert gas (e.g., He, Ar, Kr, Xe, Ne), optionally an oxidizing gas (e.g., O2, O3, CO, CO2, SO2, SO2, FNO, NO, NO2, HO), optionally a fluorocarbon and / or hydrofluorocarbon gas (e.g., C4F8, C4F6, CH2F2), and optionally additional gases (e.g., SF6, H2, Cl2, F2, Br2, HCl, HBr) is used to form reactive species and ions in the plasma. The workpiece could be any type of target, as long as it can be processed by plasma etching.

[0067] As used herein, "high aspect ratio etching" refers to the formation of a pattern having apertures in a target film by a plasma etching method when the aspect ratio (height-to-width ratio) of the formed apertures exceeds a value of 5. High anisotropy of the plasma etching process is required to achieve high aspect ratios of the etched structures. To achieve process anisotropy (vertical directional etching while lateral etching is minimized), polymer formation on the sidewalls of the etched structures is typically used. Preferential polymer formation on the sidewalls of the etched structures is achieved by competition between the etching process (polymer removal) and the deposition process (polymer formation). The presence of directional (vertical) etching by ion bombardment allows polymer to be removed more effectively on horizontal surfaces than on vertical surfaces, resulting in the promotion of polymer formation on the vertical sidewalls. Furthermore, fine-tuning the balance between the etching and deposition processes allows for preferential etching of the workpiece in the vertical direction while lateral etching is suppressed, thereby preserving the horizontal dimensions of the etched structures.

[0068] FIG. 1A is a cross-sectional view of a block diagram illustrating an exemplary initial structure of a workpiece used in the disclosed plasma etching process. As shown, silicon wafer 1 has target plasma etch film 2 formed on top of silicon wafer 1. Silicon wafer 1 can be a monocrystalline silicon wafer. Target plasma etch film 2 can be silicon oxide, silicon nitride, or a combination thereof, such as a stack of alternating silicon oxide and silicon nitride films. The thickness of target plasma etch film 2 is indicated as numeral 3. On top of target plasma etch film 2 is a patterned non-target etch film 4 having a thickness indicated as numeral 5 and a bottom diameter of the open pattern indicated as numeral 6. Non-target etch film 4 can be a patterned mask layer. Non-target etch film 4 can be a patterned film of amorphous carbon, amorphous silicon, doped amorphous carbon, doped amorphous silicon, metal, etc.

[0069] FIG. 1B shows a cross-sectional view of a block diagram illustrating an exemplary etched profile of a workpiece subjected to an etching process in which apertures with high aspect ratios are formed in a target plasma etched film 2. Number 7 is the thickness of the non-target etched film 4 after the etching process. Number 8 is the depth of the high aspect ratio aperture in the target plasma etched film 2. Number 9 is the diameter of the top of the high aspect ratio aperture in the target plasma etched film 2 (hereinafter "top CD"). Number 10 is the diameter of the widest portion of the high aspect ratio aperture in the target plasma etched film 2 (hereinafter "bow CD"). Number 11 is the diameter of the bottom of the high aspect ratio aperture in the target plasma etched film 2 (hereinafter "bottom CD"). The term "neck CD" corresponds to the thinnest portion of the etched aperture. In this disclosure, the portion of the etched aperture with the smallest diameter in the mask area (number 12) is referred to.

[0070] To determine etching performance, blanket, trench, hole, or aperture-patterned wafers are studied, where the layer to be etched is deposited on a Si substrate, determining the initial film thickness. The wafer is etched using a plasma consisting of a fluorocarbon or hydrofluorocarbon and additive gas-based mixture. The etched layer is partially or completely removed to produce a second specified film thickness. The difference between the first and second specified thicknesses defines the amount of etched material. The ratio of the amount of etched material between different layers (e.g., bulk material, mask, sacrificial layer) determines the selectivity. The pattern lateral dimensions (e.g., width for trenches or diameter for holes) at different depths (top, neck, bow, and bottom) are also evaluated. The difference in diameter between the etched and unetched patterns, as well as the change in circularity (in the case of hole patterns), determine the level of profile quality control.

[0071] In some cases, it is possible to achieve so-called infinite selective etching when the etch target material is etched while the thickness of the non-etched materials remains unchanged or increases (polymer deposition protects them from etching) after the etching process. Typically, infinite selectivity comes at the cost of a lower etch rate compared to less selective processes.

[0072] Process gas In the disclosed etching method, the selection of the process gas and the ratio of each gas concentration in the process gas mixture is required to achieve a balance between the deposition process for protection of vertical surfaces (hereinafter "passivation") and the etching process for anisotropic removal of target material. Typically, a combination of process gases is used, where each gas type plays a different role. The process gas mixture includes the disclosed oxygen-containing hydrofluorocarbon gas used as the etching gas, at least one inert gas (e.g., N, He, Ar, Kr, Xe, Ne) for plasma generation and ion bombardment promotion, an oxidizing gas (e.g., O, CO, CO) for isotropic etching and surface or gas-phase chemical reactions promotion, and at least one fluorocarbon or hydrofluorocarbon gas (e.g., CF, CF, CHF) for promoting both the anisotropic etching process of the target film and vertical surface and / or non-target film passivation.

[0073] Each gas in the process gas mixture is provided at a purity greater than 95% v / v, preferably greater than 99.99% v / v, and more preferably greater than 99.999%. Each gas in the process gas mixture contains less than 5% by volume of trace gas impurities, such as HO, with less than 150 ppm by volume of said impurity gases contained in the trace gas impurities. Preferably, the water content in the plasma etching gas is less than 20 ppm by weight. Purified products can be produced by distillation and / or passing the gas or liquid through a suitable adsorbent, such as a 4 Å molecular sieve.

[0074] Hydrofluorocarbon and fluorocarbon gases Examples of hydrofluorocarbon and / or fluorocarbon gases that can be used in the disclosed plasma etching methods include the compounds CF4, C2F6, C3F6, C4F6, C4F8, C5F8, C5F 10 , C6F 12 , C7F 12 , C8F 16, CF3I, C3F7I, C4F9I, C4H9F3Si, or C5H9F5Si. Examples of hydrofluorocarbon gases that can be used in plasma etching processes include, but are not limited to, the compounds CH2F2, CH3F, CHF3, C5HF7, C3H2F6, C3F2H4, C4H2F6, C4H3F7, and C3HF4N. Under plasma conditions, various reactive species and ions can be generated directly by dissociation of these above-mentioned fluorocarbon and hydrofluorocarbon compounds and by chemical reactions resulting from interactions between species occurring in the gas phase. Plasma etching can be achieved with any of the compounds represented by the above-mentioned compounds, whether used individually or mixed with each other. Depending on the structure of the individual compound, it can promote either etching performance, such as increasing the etch rate of a particular target material, or passivation during high aspect ratio etching processes. In particular, a mixture of CF and CF is one commonly used mixture because CF is effective in promoting passivation and CF enhances the etch rate and provides high anisotropy to the etching process. Additionally, hydrofluorocarbon gases, such as CHF, can be added to enhance the etch rate of the silicon nitride film and / or further promote polymer deposition if desired.

[0075] The disclosed hydrofluorocarbon and fluorocarbon gases are provided with a purity of greater than 95% v / v, preferably greater than 99.99% v / v, and more preferably greater than 99.999%. The disclosed hydrofluorocarbon and fluorocarbon gases contain less than 5% by volume of trace gas impurities, such as N2 and / or HO and / or CO2, with less than 150 ppm by volume of said impurity gases contained in the trace gas impurities. Preferably, the water content in the plasma etching gas is less than 20 ppm by weight. Purified products can be produced by distillation and / or passing the gas or liquid through a suitable adsorbent, such as a 4 Å molecular sieve.

[0076] The hydrofluorocarbon and fluorocarbon gases used herein may contain 0.01% v / v to 99.99% v / v of a target isomer, particularly when the isomer mixture provides improved process parameters or when isolation of that isomer is too difficult or costly. A mixture of isomers may also reduce the need for two or more gas lines to the reaction chamber.

[0077] Oxygen-containing hydrofluorocarbon gas The disclosed oxygen-containing hydrofluorocarbon gases used in the disclosed methods are represented by the formula C x H y F z O n (where 2≦x≦10, 1≦y≦15, 1≦z≦21, 1≦n≦3), and preferably at least one oxygen atom is incorporated into the molecule by an ether group or by a carbonyl group.

[0078] The disclosed oxygen-containing hydrofluorocarbon gases may contain at least one ether or carbonyl group, specifically those of the formula R1-CO-O-CH2-R1, R2-CH2-O-CH2-R2, or R3-CHF-O-CF2-R1, where R1 is H, F, C x H 2x+2-z F z or C x F 2x+2 and R2 is H, C x H 2x+2-z F z or C x F 2x+2 and R3 is F, C x H 2x+2-z F z or C x F 2x+2 where 2≦x≦3 and 1≦z≦3.

[0079] Exemplary disclosed oxygen-containing hydrofluorocarbon gases include, without limitation, C4H4F6O, C4H2F6O2, C3H2F6O, C2H2F4O, C2HF3O, C3H5F3O, C2H4F2O, C4H6F4O, C5H4F8O, C5HF 11 O, C2H3F3O and their isomers may be mentioned.

[0080] Examples of C4H4F6O isomers include 1,1,2,3,3,3-hexafluoropropyl methyl ether (CAS number: 382-34-3), bis(2,2,2-trifluoroethyl) ether (CAS number: 333-36-8), 2,2,3,4,4,4-hexafluoro-1-butanol (CAS number: 382-31-0), 1,1,1,2,3,3-hexafluoroisopropyl methyl ether (CAS number: 13171-18-1), 1,1,1,3,3,3-Hexafluoro-2-methyl-2-propanol (CAS number: 1515-14-6), 2,2,3,3-tetrafluoropropyl difluoromethyl ether (CAS number: 35042-99-0), 1,1,1,2,3,3-hexafluoro-2-methoxypropane (CAS number: 568550-25-4), hexafluoroisopropyl methyl ether (CAS number: 27215-56-1), 1-(2,2-difluoropropyl methyl ether) fluoroethoxy)-1,1,2,2-tetrafluoroethane (CAS: 50807-77-7), 2,2,3,3,4,4-hexafluoro-1-butanol (CAS number: 60838-59-7), 1,1,2,2,3,3-hexafluoro-1-methoxypropane (CAS number: 160620-20-2), 1-propanol, 2-(difluoromethyl)-2,3,3,3-tetrafluoro (CAS number: 318293-89-9), 1 , 1,1,4,4,4-hexafluoro-2-butanol (CAS No.: 86884-17-5), 1-hydro-1-methoxyhexafluoropropane (CAS No.: 123202-00-6), 1,1,2,2,3,3-hexafluorobutan-1-ol (CAS No.: 119398-75-3), and 3,3,3-trifluoro-2-(trifluoromethyl)propan-1-ol (CAS No.: 81503-71-1).

[0081] Examples of C4H2F6O2 isomers include 3,3,3-trifluoro-2-(trifluoromethyl)propanoic acid (CAS number: 564-10-3), 2,2,2-trifluoroethyl trifluoroacetate (CAS number: 407-38-5), 2,2,3,3,4,4-hexafluorobutanoic acid (CAS number: 679-12-9), 2,2,3,4,4,4-hexafluorobutanoic acid (CAS number: 379-90-8), 1,1,1,3,3,3-hexafluoro-2-propanyl formate (CAS number: 856766-70-6), trifluoromethyl 3,3,3-trifluoropropanoate (CAS number: 93667-89-1), (2E)-1,1,1,4,4,4-hexafluoro-2-butene-2,3-diol (CAS number: 856295-72-2), and 1,1,1,4,4,4-hexafluoro-3-hydroxy-2-butanone (CAS number: 1683-73-4).

[0082] The disclosed oxygen-containing hydrofluorocarbon gas is provided with a purity of greater than 95% v / v, preferably greater than 99.99% v / v, and more preferably greater than 99.999% v / v. The disclosed oxygen-containing hydrofluorocarbon gas contains less than 5% by volume of trace gas impurities, such as N2 and / or HO and / or CO2, with less than 150 ppm by volume of said impurity gases contained in the trace gas impurities. Preferably, the water content in the plasma etching gas is less than 20 ppm by weight. Purified products can be produced by distillation and / or passing the gas or liquid through a suitable adsorbent, such as a 4 Å molecular sieve.

[0083] The disclosed oxygen-containing hydrofluorocarbon gases may contain 0.01% v / v to 99.99% v / v of a target isomer, particularly when an isomer mixture provides improved process parameters or when isolation of the target isomer is too difficult or costly. A mixture of isomers may also reduce the need for two or more gas lines to the reaction chamber. As a reminder, some of the disclosed oxygen-containing hydrofluorocarbon compounds are non-gaseous compounds (i.e., liquid or solid) at room temperature and atmospheric pressure, and their gaseous form can be generated by a conventional evaporation step, such as direct evaporation, or by bubbling with an inert gas (N, Ar, He, etc.). The non-gaseous compound can be supplied in a liquid state to an evaporator, where it is evaporated, after which it is introduced into the reactor.

[0084] The disclosed oxygen-containing hydrofluorocarbon molecules having at least one ether group or at least one carbonyl group may result in improved uniformity of the shape of etched holes by exploiting better control of the polymer film deposition profile (e.g., increased anisotropy and / or bow) compared to when O is used. Furthermore, the use of molecules from the disclosed oxygen-containing hydrofluorocarbon molecules allows for etching of Si-containing compounds at higher etch rates while having lower amorphous carbon etch rates compared to standard fluorocarbon gases (e.g., CF, CH, F, CF), resulting in improved selectivity to mask layers during etching of high aspect ratio structures. The disclosed oxygen-containing hydrofluorocarbon molecules having at least one ether group or at least one carbonyl group may be beneficial for improving high aspect ratio etching processes associated with the generation of oxygen-containing hydrofluorocarbon and / or oxygen-containing fluorocarbon fragments due to dissociation of the disclosed oxygen-containing hydrofluorocarbon molecules having at least one ether group in the plasma. O2 is commonly used in plasma gas mixtures to control both the etch rate and etch profile of Si-containing films by adjusting the thickness of the deposited fluorinated polymer film. However, O2 is also effective in etching amorphous carbon mask layers, leading to reduced selectivity. Furthermore, the addition of O2 promotes isotropic etching, resulting in removal of the fluorinated polymer protective film and amorphous carbon mask, reduced sidewall protection, and undesirable distortion of the pattern profile (e.g., increased diameter, bowing). That is, amorphous carbon masks and deposited polymer films are etched faster and more isotropically using O2. The disclosed oxygen-containing hydrofluorocarbon molecules can provide a more anisotropic etching process, resulting in better profile control and lower amorphous carbon and fluoropolymer film etch rates. The difference between the disclosed oxygen-containing hydrofluorocarbons and fluorocarbons with the addition of molecular oxygen is the reactive species generated in the plasma.The oxygen-containing fluorocarbon and hydrofluorocarbon fragments generated in the plasma by dissociation of the disclosed oxygen-containing hydrofluorocarbon molecules are less reactive with carbon-based materials than oxygen radicals formed from molecular oxygen; therefore, in the case of oxygen-containing hydrofluorocarbon gases, additional ion bombardment is required to react and remove amorphous carbon and fluorinated polymer films, resulting in higher anisotropy. Furthermore, the following examples demonstrate that fluorocarbon-based fragments from oxygen-containing fluorocarbon and hydrofluorocarbon molecules can preferentially deposit on pattern sidewalls, providing additional protection, while both fluorocarbon and oxygen-containing fluorocarbon fragments enable high etching rates for Si-containing materials.

[0085] The disclosed oxygen-containing hydrofluorocarbon gases can improve etch rate, etched structure profile control, and selectivity by generating oxygen-containing fluorocarbon or hydrofluorocarbon reactive species along with fluorocarbon or hydrofluorocarbon fragments when molecular O flow rate in the etching gas mixture is reduced or eliminated.

[0086] The disclosed oxygen-containing hydrofluorocarbon molecules also provide higher etch rates than molecules of the same composition but without oxygen. Furthermore, because they achieve higher etch rates and improved etch profile control, the disclosed oxygen-containing hydrofluorocarbon molecules typically have lower global warming potentials compared to standard gases.

[0087] Higher etch rates can be achieved as follows. First, effective oxygen-containing fluorocarbon and / or hydrofluorocarbon fragments can reach the bottom of high-aspect-ratio structures more easily due to their potentially low sticking coefficient. Second, thanks to the oxygen in the fragments, fluorine and oxygen atoms are simultaneously delivered to the surface being etched, making it easier to control the reactivity and thickness of the polymer and intermixed layer at the bottom of the high-aspect-ratio structure. Thus, the disclosed oxygen-containing hydrofluorocarbon molecules are effective for anisotropic etching, and there may be two mechanisms involved. First, by providing a high density of F- and O-containing radicals and ions from the plasma, a thin F- and O-rich polymer is generated on the bottom of the high-aspect-ratio structure (the F- and O-containing radicals and ions are highly reactive and provide isotropic etching). Second, oxygen-free hydrofluorocarbon and fluorocarbon fragments can also be generated in the disclosed etching process, depositing a protective polymer film on the sidewalls and protecting the amorphous carbon mask along with the sidewalls. The protective polymer film is formed primarily by oxygen-free carbon-containing fragments as explained above.

[0088] Figure 2 summarizes the fragments and molecules present in the plasma afterglow recorded by quadrupole mass spectrometry (QMS) using 25 eV electron energy when C4H2F6O2 or a mixture of C4H2F6 + O2 was fed into the etching chamber at flow rates resulting in equal supplies of C, H, F, and O atoms. From the QMS spectra, it can be seen that higher amounts of CO and CO2 fragments were observed in the case of the oxygen-containing hydrofluorocarbon (C4H2F6O2) compared to the C4H2F6 + O2 gas mixture. Furthermore, the C3H2F3O2 oxygen-containing fragment was formed from C4H2F6O2 by direct dissociation of C4H2F6O2, but this oxygen-containing fragment C3H2F3O2 was not formed from the C4H2F6 + O2 gas mixture (mostly observed in the case of the hydrofluorocarbon fragment C4H2F6 + O2). This confirms that the incorporation of oxygen atoms into hydrofluorocarbon molecules (i.e., oxygen-containing hydrofluorocarbons) allows for the production of oxygen-containing reactive species by direct dissociation of the oxygen-containing hydrofluorocarbon molecules, which allows for the simultaneous delivery of O and F atoms to the surface being etched and enhances the etching rate.

[0089] On the other hand, in the case of the C4H2F6 + O2 gas mixture, a strong signal from the C4H2F6 parent molecule was recorded, indicating a low rate of dissociation. In contrast, no signal from the oxygen-containing hydrofluorocarbon, C4H2F6O2, was recorded in the case of C4H2F6O2, indicating that it is easier to dissociate the C4H2F6O2 molecule and ionize it by electron impact. The high rate of dissociation of the C4H2F6O2 molecule can be explained by the weak bonds in the ether groups, which easily break these bonds upon electron impact and lead to the dissociation of the molecule. Therefore, it is preferable to use oxygen-containing hydrofluorocarbons in which at least one oxygen atom is incorporated into an ether group or a carbonyl group to promote molecular dissociation in the plasma, thereby enhancing the generation of reactive species and increasing the etching rate.

[0090] Furthermore, in the case of C4H2F6O2, more CF3 fragments were produced compared to the C4H2F6 + O2 gas mixture under the same conditions shown in Figure 2. It indicates that the easy dissociation of C4H2F6O2 molecules due to the presence of ether groups is also beneficial for the production of fluorocarbon fragments. CF3 is one of the fluorocarbon fragments involved in etching. A higher concentration of CF3f fragments is beneficial for increasing the etching rate.

[0091] Other process gases Additional gases, such as inert gases and / or oxidizing gases, can be added to the process gas mixture. The inert gas can be one or more gases selected from N2, He, Ar, Kr, Xe, and Ne. The use of a noble gas increases ion bombardment during the etching process depending on the gas ratio in the process gas mixture. The use of a noble gas promotes or suppresses dissociation of other gases in the process gas mixture, which has a direct impact on the etch rate and anisotropy of the etching process. Furthermore, the addition of an oxidizing gas (such as O2, O3, CO, CO2, COS, SO2, SO2, FNO, NO, NO2, or HO) can increase the etch rate depending on the process gas mixture, the type of target and non-target materials, and the isotropy and selectivity of the etching process.

[0092] H2, SF6, NF3, N2, NH3, Cl2, F2, Br2, BCl3, HBr, HCl, HBr, PF 3、 Further additional gases from the list CF3I, C3F7I, C4F9I, C4H9F3Si, C5H9F5Si may be added to the etching gas mixture to improve process control or increase the etch rate.

[0093] Plasma etching method flow Most semiconductor devices are formed using a process of forming thin films on top of a substrate and patterning those films to receive desired structures and devices. Patterning includes a lithography step, which allows defining the pattern to be formed, and an etching step, which is used to remove unwanted material or films from the substrate according to the formed pattern. One commonly used etching process is plasma dry etching, in which the substrate is exposed to plasma or reactive species formed inside a process chamber. The combination of physical (e.g., sputtering due to ion bombardment) and chemical (e.g., surface interaction with reactive species) mechanisms in plasma etching makes it possible to achieve preferential etching of certain materials over other materials, depending on the chemistry and process conditions used, where volatile by-products will be formed and removed.

[0094] A detailed description of the flow of the disclosed plasma etching method is as follows: In the first step, a workpiece containing one or more target etching films and, optionally, a non-target plasma etching film that may be patterned (having some pattern, such as openings in the film) is transferred to a plasma etching chamber. The workpiece can be any type of target as long as it can be processed by plasma etching. For example, a single-crystal Si wafer containing at least one Si-containing film, an organic film, or a metal-containing film, or multiple films, some of which may be patterned.

[0095] An example of a workpiece having a patterned target etching film and a non-target etching film is shown in FIG. 1A. The plasma etching chamber consists of a vessel capable of providing a low pressure within the vessel by evacuation, a plasma generator capable of generating a plasma within the chamber, and a workpiece holder capable of holding or mounting a workpiece to be exposed to the plasma within the chamber, with temperature control using a device or gas flow (e.g., helium flow). A process gas mixture containing several gases in specific ratios that can be changed during the etching process is then introduced into the plasma etching chamber, and the pressure within the chamber is maintained at a specified value or several values ​​that can be changed during the etching process. Next, the plasma generator applies a high-frequency electromagnetic field to the process gas mixture, resulting in the formation of a glow discharge. When the workpiece is exposed to the plasma generated in the plasma etching chamber, the targeted film is removed by a combination of ion bombardment and interactions with reactive species compared to the non-target film, resulting in the formation of apertures and volatile byproducts.

[0096] Disclosed is a plasma etching method for forming structures or apertures 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, comprising: Mounting a substrate within a process chamber; introducing an etching gas containing an oxygen-containing hydrofluorocarbon vapor into the process chamber; converting the etching gas into a plasma; allowing an etching reaction to proceed 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 structures or structures; The formed structure or aperture is a high aspect ratio structure or aperture. The aspect ratio of the high aspect ratio structure or aperture may be 1:400 or less.

[0097] One or more treatment films may be Sia O b C c N d H e (where a, b, c, d, and e range from 0.1 to 6, and b, c, d, and e may each independently be 0). The one or more treatment films may also include dopants, such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge. The non-etch film may be a patterned hard mask layer, such as amorphous carbon, amorphous silicon, doped amorphous carbon, doped amorphous silicon, a metal, etc.

[0098] In the disclosed plasma etching method, the plasma etching chamber is equipped with a parallel-plate electrode plasma generator in which a 60 MHz radio frequency electromagnetic field is applied to the upper electrode and a 2 MHz one to the lower electrode, while the gap between the electrodes is maintained within a range of 10 to 35 mm. The combination of these fields allows power to be applied to the upper electrode in the range of 0 to 2000 W and to the lower electrode in the range of 1500 to 7000 W. The pressure in the etching chamber during the plasma etching process is maintained at 15 to 30 mTorr with the process gas mixture introduced.

[0099] If necessary, the container containing the disclosed oxygen-containing hydrofluorocarbon etching compound can be heated to a temperature that allows the oxygen-containing hydrofluorocarbon etching compound to be in the gas phase or in a liquid phase with sufficient vapor pressure for delivery to the plasma etching chamber or reaction chamber. The container can be maintained at a temperature ranging, for example, from about 0°C to about 150°C, preferably from about room temperature to about 100°C, and more preferably from about room temperature to about 50°C. More preferably, the container is maintained at room temperature to avoid heating the lines to the plasma etching chamber. Those skilled in the art will recognize that the temperature of the container can be adjusted in known ways to control the amount of oxygen-containing hydrofluorocarbon etching compound that vaporizes.

[0100] The temperature and pressure within the plasma etching chamber are maintained at conditions suitable for the treatment film to react with the activated etching gas. For example, the pressure within the chamber may be maintained at approximately 0.1 mTorr to approximately 1000 Torr, preferably approximately 1 mTorr to approximately 10 Torr, more preferably approximately 10 mTorr to approximately 1 Torr, and even more preferably approximately 10 mTorr to approximately 100 mTorr, as required by the etching parameters. Similarly, the substrate temperature within the plasma etching chamber may range from approximately −196° C. to approximately 500° C., preferably approximately −120° C. to approximately 300° C., more preferably approximately −100° C. to approximately 50° C.; more preferably approximately −70° C. to approximately 40° C. The chamber wall temperature may range from approximately −196° C. to approximately 300° C., depending on the process requirements.

[0101] Typical materials that need to be etched can be SiO or SiN. The etch stop layer can be silicon oxynitride (SiON), polysilicon, a metal or a metal nitride (e.g., W or TiN). The mask material used can be aC, doped aC, amorphous silicon (a-Si), doped a-Si or p-Si selected from B-doped a-C, W-doped a-C, B-doped a-Si, or a photoresist material.

[0102] The disclosed plasma etching method using the disclosed oxygen-containing hydrofluorocarbon compound as an etching gas produces apertures in silicon-containing films, such as channel holes, gate trenches, staircase contacts, capacitor holes, contact holes, contact etch, slit etch, self-aligned contacts, self-aligned vias, supervias, and the like. The resulting apertures can have aspect ratios ranging from about 5:1 to about 500:1, preferably from about 20:1 to about 400:1; and diameters ranging from about 5 nm to about 500 nm, preferably less than 100 nm. The resulting apertures can have aspect ratios greater than 5, preferably greater than 10, and more preferably greater than 20. For example, those skilled in the art will recognize that channel hole etching produces apertures in silicon-containing films with aspect ratios greater than 50. The silicon-containing film can be selected from silicon oxide, silicon nitride, crystalline Si, poly-silicon, polycrystalline silicon, amorphous silicon, low-k SiCOH, SiOCN, SiC, SiON, and the like. a O b H c C d N e (where a>0, b, c, d and e≧0), or a stack of alternating silicon oxide and silicon nitride (ONON) films or alternating silicon oxide and poly-silicon (OPOP) films.

[0103] However, the disclosed plasma etching method is by no means limited to the experimental conditions described above, and the type of plasma etching tool (e.g., capacitively coupled plasma 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 flows, workpiece, and plasma etching chamber may themselves be varied for and during each process.

[0104] In summary, the disclosed plasma etching method provides enhanced control over the deposition profile of polymer films and new chemistries capable of etching silicon oxide and silicon nitride or combinations thereof with high etch rates and selectivities. Furthermore, the disclosed oxygen-containing hydrofluorocarbon compounds have lower global warming potentials compared to commonly used gases (e.g., SF, C4F6, and C4F8), enabling more environmentally friendly processes.

[0105] Furthermore, the disclosed plasma etching method provides for the use of an oxygen-containing hydrofluorocarbon compound or gas as an etching gas, preferably an oxygen-containing hydrofluorocarbon compound or gas containing oxygen in an ether group. The disclosed oxygen-containing hydrofluorocarbon compound is effective in controlling polymer film deposition to maintain a defined etching profile while also etching Si-containing materials (e.g., SiO2, Si3N4, or a stack of alternating SiO2 and Si3N4 layers) with high etch rates and high selectivity to mask layers (e.g., amorphous carbon, amorphous silicon). The disclosed plasma etching method can be applied to etching high-aspect ratio structures, such as contact holes, channels, and high-aspect ratio capacitors, required for the fabrication of semiconductor devices such as 3D NAND and DRAM.

[0106] There are advantages to adding oxygen-containing hydrofluorocarbons to etching gas mixtures. When vapors of the disclosed oxygen-containing hydrofluorocarbons are added to etching gas mixtures, the observed improvement in performance is attributed to the generation of unique reactive species in the plasma through dissociation and the use of less to no molecular O in the gas mixture, compared to commonly used fluorocarbons and hydrofluorocarbons, such as CF, CF, and CHF. The formation of oxygen-containing reactive fluorocarbon and hydrofluorocarbon species through direct dissociation of the disclosed oxygen-containing hydrofluorocarbons in the plasma allows for the simultaneous delivery of highly reactive oxygen and fluorine to the surface of the target etching material, resulting in the formation of volatile by-products, such as fluorides and / or oxyfluorides of the etching target material. This enhances the etching rate compared to commonly used mixtures of fluorocarbons or hydrofluorocarbons with molecular oxygen, where the delivery of highly reactive oxygen and fluorine to the surface of the target etching material occurs independently, which can result in a decreased etching rate. On the other hand, the presence of oxygen in the disclosed oxygen-containing hydrofluorocarbons allows for the reduction or even elimination of the use of molecular O in the etching gas mixture, resulting in a less isotropic etching process and less damage to the sidewalls of the etched structures and masks (lateral etching). Furthermore, the generation of fluorocarbon and hydrofluorocarbon fragments by dissociation of the disclosed oxygen-containing hydrofluorocarbons, which potentially have lower sticking coefficients compared to their counterparts in plasma, allows for the deposition of more conformal polymers on the sidewalls of the etched structures and masks, thereby further improving control of the etched structure profile and mask selectivity. Here, the etched structures can be apertures, vias, voids, or trenches. The use of molecular O gas leads to the generation of oxygen-reactive species (e.g., atoms, radicals, and ions) that promote isotropic etching, which leads to damage to the amorphous carbon mask layer and the sidewall protective polymer film.In contrast, the use of disclosed oxygen-containing hydrofluorocarbon vapors (preferentially containing ether groups) as etching gases provides better control of polymer film deposition on sidewalls and masks, resulting in preferential anisotropic etching of the targeted material and improved control of the shape of the etched structure. This aids in etching high-aspect-ratio structures with thin and straight profiles by maintaining a protective film on the sidewalls during the etching process, preventing lateral etching and profile distortion. In addition, the disclosed oxygen-containing hydrofluorocarbon vapors are also effective for anisotropic etching of SiO and SiN at higher etch rates than commonly used etching chemistries (e.g., CF, CF, O), and also for SiO to SiN selectivity. The SiO to SiN selectivity using the disclosed oxygen-containing hydrofluorocarbons can range from approximately 1:20 to 20:1; preferably 1:10 to 10:1, more preferably 1:5 to 5:1, and even more preferably 1:2 to 2:1. The selectivity of SiO2 to SiN using the disclosed oxygen-containing hydrofluorocarbons can be approximately close to 1. The reduced sticking coefficient of the hydrofluorocarbons disclosed in U.S. Patent Application Publication No. 20210193475 to Ishino et al. is also beneficial for improving polymer uniformity during the etching process, resulting in better profile control of the etched structures. The disclosed oxygen-containing hydrofluorocarbons can provide higher selectivity by depositing a more conformal hydrofluorocarbon polymer to protect mask layers (e.g., aC masks) and sidewalls and by reducing the use of molecular oxygen in the etching gas mixture.

[0107] According to the present disclosure, it is possible to provide a plasma etching method that can increase selectivity to the mask while maintaining a high etch rate through the use of vapor of an oxygen-containing hydrofluorocarbon compound, and can sufficiently suppress lateral expansion of the structures being etched during a high aspect ratio etching process. [Example]

[0108] A more detailed description of the disclosed method by way of example is provided below: However, the disclosed method is in no way limited to the examples presented, and the process conditions, process gas mixture, combinations and proportions of gases in the gas mixture, workpiece, and plasma etching chamber may themselves vary.

[0109] The plasma etching conditions, plasma etching chamber and workpieces along with the results of the plasma etching process are described in the following examples.

[0110] Plasma Etching Device In the disclosed method, a parallel-plate (capacitively coupled plasma) plasma generator was used as the plasma etching device. The parallel-plate configuration included an upper electrode and a lower electrode on which the workpiece was placed (the lower electrode was used as a sample holder with temperature control). The separation between the electrodes was 20 mm. The upper electrode was connected to a 60 MHz generator, while the lower electrode was connected to a 2 MHz generator.

[0111] Plasma etching conditions During the plasma etching process, the power supplied to the upper electrode was varied within a range of 500-2000 W, while the power supplied to the lower electrode was varied within a range of 750-7000 W. The pressure was maintained constant throughout the process at a value selected within a range of 15-30 mTorr. The plasma etching time was set to a value between 30 and 300 seconds. The etching rate was estimated in nanometers per minute. The plasma process gas mixture included at least one gas from the following list: Ar, O, C4H2F6 as a hydrofluorocarbon gas, and C4H2F6O2 or C4H4F6O as an oxygen-containing hydrofluorocarbon gas.

[0112] workpiece In Examples 1-5 and 11-17, the workpiece shown in FIG. 1A was used. The target etching film 2 was a 3000 nm thick SiO film (number 3). The non-target etching material 4 was an 868 nm thick patterned film of amorphous carbon (number 5). The bottom diameter of the open pattern in the amorphous carbon film 4 (number 6) was approximately 120 nm. An example of the workpiece profile after the etching process was performed is shown in FIG. 1B.

[0113] In Examples 6 to 10, a single crystal silicon planar wafer workpiece having a 2000 nm thick target-etching SiO2 film deposited on top of the single crystal silicon planar wafer was used for silicon oxide etching; a single crystal silicon planar wafer workpiece having a 2000 nm thick target-etching Si3N4 film deposited on top of the single crystal silicon planar wafer was used for silicon nitride etching.

[0114] Plasma Etch Profile and Selectivity For comparison of the high aspect ratio etch performance of the disclosed plasma etch process and a control plasma etch process using molecules with the same amount of C, H, and F atoms but excluding O, reference is made to Figures 1A and 1B, selectivity, top CD, neck CD, and bow CD, which can provide control over the etched pattern profile. Selectivity was calculated as the ratio of the silicon dioxide etch depth (number 8 in Figure 1B) to the difference between the initial amorphous carbon mask thickness (number 5 in Figure 1A, i.e., 868 nm) and the mask thickness of the mask after the etch process (number 7 in Figure 1B). In the event that a negative value of selectivity is obtained (i.e., the thickness of the amorphous carbon mask increases after the etch process), this condition is referred to as a condition of "infinite selectivity," which means that the mask thickness increases due to the etch process.

[0115] During the comparison, higher values ​​of selectivity are targeted when the top CD (number 9 in FIG. 1B) and neck CD (number 12 in FIG. 1B) are targeted to be as close as possible to the value of the bottom diameter of the opening in the amorphous carbon mask (i.e., 120 nm, number 6 in FIG. 1A).

[0116] Example 1 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The pressure in the chamber was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A process gas mixture containing the following gas flow rates: 150 sccm Ar and 65 sccm C4H2F6O2 was introduced into the plasma etching chamber. The plasma etching process was carried out for 1 minute. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparative results are summarized in Table 1.

[0117] Example 2 Plasma etching was performed in the same manner as in Example 1, except that the process gas mixture was replaced with the following: 150 sccm Ar, 65 sccm O, and 65 sccm C4H2F6. The resulting structure of the cross section of the workpiece after the etching process was observed by SEM (not shown), and the comparative results are summarized in Table 1.

[0118] Example 3 Plasma etching was performed in the same manner as in Example 1, except that the process gas mixture was replaced with the following: 150 sccm Ar, 19.5 sccm O, and 65 sccm C4H2F6O2. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparative results are summarized in Table 1.

[0119] Example 4 Plasma etching was performed in the same manner as in Example 1, except that the process gas mixture was replaced with the following: 150 sccm Ar, 84.5 sccm O, and 65 sccm C4H2F6. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparative results are summarized in Table 1.

[0120] [Table 1]

[0121] Example 5 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set at 20 mm. One of the following gas mixtures was introduced into the plasma etching chamber at a specified gas flow rate: 150 sccm Ar, 13 sccm O, 65 sccm C4H2F6O2, or 150 sccm Ar, 78 sccm O, 65 sccm C4H2F6. The plasma etching process was performed for 1, 3.5, or 6.5 minutes. The resulting etch rates as a function of the aspect ratio of the etched structures are summarized in Figure 3.

[0122] The results observed in Table 1 indicate that the deposited polymer film on the sidewalls of the aC mask and etched structures was anisotropically etched by oxygen-containing hydrofluorocarbon reactive species generated from C4H2F6O2 and directional ion bombardment (vertical), leading to lateral etching and the lack of polymer film growth on the sidewalls of the mask and etched structures in Example 1. Conversely, in the case of the C4H2F6 and O2 gas mixture in Example 2, a more isotropic etching process was observed due to the generation of highly reactive oxygen species from O2, resulting in lateral etching, CD enlargement, and less to no polymer deposition on the sidewalls. Since the process conditions in both Examples 1 and 2 were chosen to achieve the same number of C, H, F, O, and Ar atoms in the gas mixture and all other parameters were the same except for the method of supplying oxygen (in C4H2F6O2 or with O2), it clearly demonstrates the difference between incorporating oxygen into hydrofluorocarbon molecules and O2 molecules. This means that the observed differences in results were solely due to the method of supplying oxygen, either from C4H2F6O2 or O2. It can be concluded that supplying oxygen by using oxygen-containing hydrofluorocarbons as etching gases results in improved polymer deposition and improved selectivity due to higher anisotropy and control of the etched structure profile compared to the use of molecular O2.

[0123] The initial workpiece with the patterned mask, the SiO2 holes etched using the conditions from Example 1 with a C4H2F6O2 / Ar etching gas mixture, and the SiO2 holes etched using the conditions from Example 2 with a C4H2F6 / O2 / Ar gas mixture were measured by SEM (not shown), and the comparative results are summarized in Table 1.

[0124] As can be seen in Table 1, the addition of a small amount of O to the Ar / C4H2F6O2 etching gas mixture in Example 3 results in a significant increase in the etch rate compared to the case without O2 in Example 1. Furthermore, it can be observed that in Experiment 4, where oxygen is supplied solely by O2 molecules, the etch rate is lower and the lateral etching is much faster compared to the results from Experiment 3, where oxygen was supplied primarily from C4H2F6O2. The faster etch rate, reduced lateral etching, and improved control of the etched structure profile demonstrated in Example 3 clearly indicate that the use of oxygen-containing hydrofluorocarbons is essential for etching high aspect ratio structures. Considering that the numbers of C, F, H, and O atoms in the gas mixtures in Examples 3 and 4 are the same, it can be concluded that the incorporation of oxygen atoms into the hydrofluorocarbon molecules in the case of C4H2F6O2 is beneficial for increasing the etch rate and increasing the anisotropy compared to the use of a C4H2F6 / O2 gas mixture. The proposed mechanism is that the oxygen-containing fluorocarbon and hydrofluorocarbon fragments produced by the dissociation of C4H2F6O may have lower sticking coefficients compared to fragments produced from commonly used fluorocarbon or hydrofluorocarbon gases; therefore, the fluorocarbon and hydrofluorocarbon fragments can easily reach the bottom of the etched features and simultaneously deliver F and O, creating a thin F- and O-rich polymer film on the bottom, promoting the formation of volatile by-products and enhancing the etch rate.

[0125] The results summarized in Table 1 support the above statement. It can be noted that when O2 is not added to C4H2F6O2 in Example 1, the process is characterized by favorable deposition, resulting in polymer film growth, reduction of both top and neck CDs, and a slower etch rate when compared to the C4H2F6 / O2 gas mixture in Example 2. However, in Example 3, where a small amount of O2 was added to C4H2F6O2, the top and neck CDs were nearly identical to the initial values, which then became significantly larger due to the lateral etching in Example 4, where a C4H2F6 / O2 mixture was used to match the C, H, F, and O atom counts to Example 3. Furthermore, in Example 3, infinite selectivity to the mask was achieved along with a higher etch rate compared to Example 4, in addition to good preservation of the top and neck CDs. The observed results demonstrate that when oxygen is introduced into the etching gas mixture using an oxygen-containing hydrofluorocarbon vapor instead of molecular O2, or when oxygen is introduced using a combination of molecular O2 and an oxygen-containing hydrofluorocarbon vapor, it is possible to improve all of the comparative results (etch rate, top CD, and neck CD) while maintaining infinite or high values ​​of selectivity. The ability to maintain top and neck CDs near initial values ​​after etching in Example 3 demonstrates exceptional control of the shape of the etched structures when oxygen-containing hydrofluorocarbons are added to the etching gas mixture or used as the primary etchant.

[0126] The results in Figure 3 show that the use of oxygen-containing hydrofluorocarbon gases also provides higher etch rates at higher aspect ratios of the etched features compared to the use of hydrofluorocarbon and molecular oxygen gas mixtures. The observed higher etch rates were explained in the discussion of Table 1, and should remain the same as aspect ratios increase. A proposed mechanism may be the reduced sticking coefficient of the oxygen-containing hydrofluorocarbon and fluorocarbon fragments, which allows them to more easily reach the bottom of high aspect ratio features and simultaneously donate F and O to the surface being etched.

[0127] Example 6 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set at 20 mm. The following gas mixture was introduced into the plasma etching chamber at specified gas flow rates: 150 sccm Ar, 65 sccm C4H2F6O2, and O2 with flow rates varying from 0 to 40 sccm. The plasma etching process was performed for 2 min. The resulting SiO2 and Si3N4 etch rates and SiO2 / Si3N4 selectivity as a function of O2 flow rate are shown in Figure 4A.

[0128] Example 7 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set at 20 mm. The following gas mixture was introduced into the plasma etching chamber at specified gas flow rates: 150 sccm Ar, 65 sccm C4H2F6, and O2 at flow rates varying from 0 to 40 sccm. The plasma etching process was performed for 2 min. The resulting SiO2 and Si3N4 etch rates and SiO2 / Si3N4 selectivity as a function of O2 flow rate are shown in Figure 4B.

[0129] Example 8 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set at 20 mm. The following gas mixture was introduced into the plasma etching chamber at specified gas flow rates: 150 sccm Ar, 65 sccm C4F8, and O2 at flow rates varying from 0 to 40 sccm. The plasma etching process was performed for 2 min. The resulting SiO2 and Si3N4 etch rates and SiO2 / Si3N4 selectivity as a function of O2 flow rate are shown in Figure 4C.

[0130] Example 9 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set at 20 mm. The following gas mixture was introduced into the plasma etching chamber at specified gas flow rates: 150 sccm Ar and 65 sccm C4H4F6O (bis(2,2,2-trifluoroethyl) ether, CAS: 333-36-8), with O2 flow rates varying from 52 to 91 sccm. The plasma etching process was performed for 2 min. The resulting SiO2 and Si3N4 etch rates and SiO2 / Si3N4 selectivity as a function of O2 flow rate are shown in Figure 4D. The SiO2 / Si3N4 selectivity as a function of O2 flow rate can reach values ​​close to 1, which is in the favorable range for ONON stack etching.

[0131] Example 10 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. The following gas mixture was introduced into the plasma etching chamber at specified gas flow rates: 150 sccm Ar, 65 sccm C4H4F6O (1,1,2,3,3,3-hexafluoropropyl methyl ether, CAS: 382-34-3), and O2 flow rates varying from 26 to 78 sccm. The plasma etching process was performed for 2 min. The resulting SiO2 and Si3N4 etch rates and SiO2 / Si3N4 selectivity as a function of O2 flow rate are shown in Figure 4E. The SiO2 / Si3N4 selectivity as a function of O2 flow rate can reach values ​​close to 1, which is in the favorable range for ONON stack etching.

[0132] From Figures 4A-4E, it can be observed that when C4H2F6O2 / Ar / O2 or C4H4F6O / Ar / O2 gas mixtures are used as etching gases, it is possible to etch both SiO2 and Si3N4 at higher etch rates compared to C4H2F6 / Ar / O2 etching gas mixtures under identical conditions. As previously discussed, the higher etch rates can be attributed to two characteristics of oxygen-containing hydrofluorocarbons: the generation of oxygen-containing fluorocarbon or hydrofluorocarbon reactive species and the easier dissociation of the molecules in the plasma (if an ether group is present in the molecule). The formation of oxygen-containing reactive species allows for the simultaneous delivery and easy dissociation of O and F atoms to the surface being etched, enabling the production of a larger amount of reactive species, which, combined, enhances the etch rate.

[0133] On the other hand, from Figure 4C, it can be observed that despite the higher etch rate of SiO2 for the C4F8 / Ar / O2 gas mixture compared to C4H2F6O2 / Ar / O2, the etch rate of Si3N4 is almost an order of magnitude lower under the same conditions. This clearly indicates that oxygen-containing hydrofluorocarbons can provide etching of both SiO2 and Si3N4 at reasonable and comparable etch rates, which is not possible when only a mixture of fluorocarbons and molecular oxygen is used as the etching gas.

[0134] Another important observation from Figure 4A is that the etch SiO2 to Si3N4 selectivity varies widely with O2 flow rate. That is, 13 sccm O2 preferentially etches SiO2, 26 sccm O2 etches both SiO2 and Si3N4 at similar etch rates, and higher O2 flow rates can etch Si3N4 preferentially. The ability to etch SiO2 and Si3N4 at similar rates and the variability of SiO2 to Si3N4 etch selectivity with O2 flow rate appear essential for ON-ON stack high aspect ratio etches (typically used in DRAM fabrication), where precise control of both SiO2 and Si3N4 etch rates is required to achieve vertical profiles without profile distortions (such as scalloping) after etching.

[0135] From a summary of the observations in Examples 1-5, it can be concluded that the subsequent addition of an oxygen-containing hydrofluorocarbon, preferably C4H4F6O or C4H2F6O2, with at least one oxygen atom incorporated into an ether group, to the gas mixture can improve selectivity during high aspect ratio etching, maintaining the lateral dimensions of the structures, while also improving the etch rate compared to a mixture of hydrofluorocarbon and molecular O2 gas. Furthermore, it was confirmed that the observed improvement in etch rate only increases with increasing aspect ratio, which is essential for high aspect ratio etching processes. Meanwhile, from a summary of the observations in Examples 6-8, it can be concluded that the use of an oxygen-containing fluorocarbon in the etching gas mixture allows for more effective etching of Si3N4 compared to commonly used fluorocarbon or hydrofluorocarbon gases under identical conditions. Furthermore, it is possible to control the SiO2 to Si3N4 etching selectivity by varying the O2 flow rate when using an oxygen-containing hydrofluorocarbon as the etching gas. 4A, 4D, and 4E, it can be observed that with increasing O flow rate, the SiO to SiN selectivity gradually reaches a range of 1:2 to 2:1, gradually reaching a value close to 1. Considering the advantageous range of selectivity, the disclosed oxygen-containing hydrofluorocarbons can be applied to ON-ON stack etching. Therefore, due to their exceptional ability of etch profile control, high etch rate and selectivity, and fine tuning of SiO and SiN etch rates, vapor of oxygen-containing hydrofluorocarbon compounds appears promising as an etching gas or additive to etching gas for high aspect ratio etching of Si-containing films (SiO, SiN, and especially ON-ON stacks) in the fabrication of semiconductor devices (such as 3D NAND and DRAM).

[0136] Example 11 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The pressure inside the chamber was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A gas mixture containing the following gases was then introduced into the plasma etching chamber: 150 sccm Ar, 71 sccm O, and 65 sccm C4H4F6O (bis(2,2,2-trifluoroethyl) ether, CAS: 333-36-8). The plasma etching process was carried out for 1 minute. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparative results are summarized in Table 2.

[0137] Example 12 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The pressure in the chamber was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A gas mixture containing the following gases was then introduced into the plasma etching chamber: 150 sccm Ar, 104 sccm O, and 65 sccm C4H2F6. The plasma etching process was carried out for 1 minute. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparison criteria are summarized in Table 2.

[0138] The data summarized in Table 2 demonstrates a comparison between C4H4F6O and C4H2F6 + O2 gases to verify the difference between adding O2 to the gas mixture and including oxygen in the molecule when the total O2 flow rate is the same. From Table 2, it can be clearly observed that incorporating oxygen in the molecule allows for a significant improvement in the preservation of the lateral dimensions of the structure. This can be explained by the decrease in the isotropic etch rate caused by free oxygen radicals in the case of C4H4F6O due to the lower O2 rate. This correlates well with the results observed in Table 1 for C4H2F6O2. The observed data demonstrate that it is possible to improve most of the etched structure profile parameters (bow CD, top CD, and neck CD) while maintaining infinite or high values ​​of selectivity when oxygen is introduced into the etching gas mixture using an oxygen-containing hydrofluorocarbon gas instead of molecular O2 or a combination of molecular O2 and oxygen-containing hydrofluorocarbon gas.

[0139] Example 13 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The pressure inside the chamber was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A gas mixture containing the following gases was then introduced into the plasma etching chamber: 150 sccm Ar, 71 sccm O, 20 sccm C4F6, and 45 sccm C4H4F6O (bis(2,2,2-trifluoroethyl) ether, CAS: 333-36-8). The plasma etching process was carried out for 3 minutes. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparison criteria are summarized in Table 2.

[0140] Example 14 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The pressure inside the chamber was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A gas mixture containing the following gases was then introduced into the plasma etching chamber: 150 sccm Ar, 104 sccm O, 20 sccm CF, and 45 sccm CF. The plasma etching process was carried out for 3 minutes. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparison criteria are summarized in Table 2.

[0141] The data summarized in Table 2 demonstrates a comparison between C4H4F6O and C4F8 gases as the primary etchant in an Ar+O2+C4F6 etching recipe. It can be clearly observed that C4H4F6O provides a dramatic improvement in selectivity and structural profile control compared to C4F8. Considering that the total flow rate of O atoms into the chamber was the same in both examples, it indicates that combining O into molecules allows for improved selectivity and profile control by reducing the required molecular O2 flow, which correlates well with the results observed in Examples 1-10.

[0142] Example 15 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The pressure in the chamber was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A gas mixture containing the following gases was then introduced into the plasma etching chamber: 150 sccm Ar, 30 sccm O, and 60 sccm CF. The plasma etching process was carried out for 2 minutes. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparison criteria are summarized in Table 2.

[0143] Example 16 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A gas mixture containing the following gases was then introduced into the plasma etching chamber: 150 sccm Ar, 30 sccm O, 60 sccm C4F8, and 10 sccm C4H4F6O (1,1,2,3,3,3-hexafluoropropyl methyl ether, CAS: 382-34-3). The difference between Example 14 and Example 15 is that in Example 15, the addition of C4H4F6O was added to the gas mixture of Example 14, where C4H4F6O served as an additive gas. The plasma etching process was carried out for 2 minutes. The resulting structure of the cross section of the workpiece after the etching process was observed by SEM (not shown), and the comparison criteria are summarized in Table 2.

[0144] Example 17 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The chamber pressure was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A gas mixture containing the following gases was then introduced into the plasma etching chamber: 150 sccm Ar, 30 sccm O, 50 sccm C4F8, and 10 sccm C4H4F6O (1,1,2,3,3,3-hexafluoropropyl methyl ether, CAS: 382-34-3). The difference between Example 14 and Example 16 is that in Example 16, the flow rate of CF was reduced from 60 sccm to 50 sccm, so that CF in the gas mixture used in Example 14 was partially replaced with the addition of CHFO. The plasma etching process was carried out for 2 minutes. The resulting structure of the cross section of the workpiece after the etching process was observed by SEM (not shown), and the comparison criteria are summarized in Table 2.

[0145] As shown in Table 2, either the addition of C4H4F6O to the gas mixture (Example 15) or the partial replacement of C4F8 in the gas mixture with C4H4F6O (Example 16) compared to Example 14 allows for significant improvement in the etched structure profile compared to the baseline recipe using an Ar+O2+C4F8 gas mixture (Example 14). From the more detailed measurement results shown in Table 2, it can be concluded that the use of C4H4F6O as an additive or partial replacement gas allows for preservation of lateral dimensions and improved selectivity. As discussed above, the improved selectivity can be attributed to the generation of fragments by dissociating C4H4F6O compared to standard chemistry (Ar+O2+C4F8) and the production of a larger number of reactive species due to easy ether group dissociation, which allows for increased polymer deposition and selectivity on top of the mask. Meanwhile, the preservation of lateral dimensions and reduced bowing can be attributed to the potentially lower sticking coefficient of the fragments generated from C4H4F6O, which allows for more conformal polymer deposition and sidewall preservation.

[0146] [Table 2]

[0147] From a summary of the observations in Examples 1-5 and 11-17, it can be concluded that the addition of an oxygen-containing hydrofluorocarbon, preferably C4H4F6O or C4H2F6O2, with at least one oxygen atom incorporated into an ether group, to a process gas mixture allows for improved selectivity and preservation of the lateral dimensions of structures during high aspect ratio etching, while also improving the etch rate, compared to a mixture of hydrofluorocarbon and molecular O2 gas. Furthermore, the observed improvement in etch rate is confined to increasing aspect ratios, which is essential for high aspect ratio etching processes. The positive effect is verified in various gas mixtures, such as Ar / O2 / C4F6, Ar / O2 / C4F8, or Ar / O2, when the oxygen-containing hydrofluorocarbon gas is used as either the primary etchant, additive, or replacement gas. On the other hand, from the summary of the observations in Examples 6-9, it can be concluded that the use of oxygen-containing hydrofluorocarbons in the etching gas enables more effective etching of Si3N4 compared with commonly used fluorocarbon or hydrofluorocarbon gases under the same conditions, which can be explained by the easy dissociation of the molecules on the ether group, which leads to the generation of a large number of reactive chemical species. Furthermore, when oxygen-containing hydrofluorocarbons are used as etching gases, it is possible to control the etching selectivity of SiO2 versus Si3N4 by changing the O2 flow rate. Therefore, due to their exceptional ability of etching profile control, high etching rate and selectivity, and fine-tuning of SiO2 and Si3N4 etching rates, the vapor of oxygen-containing hydrofluorocarbon compounds appears promising as an etching gas or additive to etching gases for high aspect ratio etching of Si-containing films (e.g., SiO2, Si3N4, and O / N stacks) in the fabrication of semiconductor devices, such as 3D NAND and DRAM.

[0148] Although the subject matter described herein may be described in connection with example implementations for processing one or more computing application features / operations for a computing application having a user-interactive component, the subject matter is not limited to these particular embodiments. Rather, the techniques described herein may be applied to any suitable type of user-interactive component performance management method, system, platform, and / or device.

[0149] Example 18 Plasma etching was performed in a plasma etching chamber in which 1400 W of power was applied to the top electrode at a frequency of 60 MHz, 7000 W of power was applied to the bottom electrode at a frequency of 2 MHz, and the power applied to both the top and bottom electrodes was pulsed at 500 Hz with a 60% duty cycle. The pressure in the chamber was maintained at 25 mTorr, and the gap between the electrodes was set to 20 mm. A process gas mixture containing the following gas flow rates: 150 sccm Ar, 32.5 sccm O, and 65 sccm C3H2F6O was introduced into the plasma etching chamber. The plasma etching process was performed for 1 minute. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparative results are summarized in Table 3.

[0150] Example 19 Plasma etching was performed in the same manner as in Example A, except that the process gas mixture was replaced with the following: 150 sccm Ar, 65 sccm O, and 65 sccm C3H2F6. The resulting structure of the cross-section of the workpiece after the etching process was observed by SEM (not shown), and the comparative results are summarized in Table 3.

[0151] [Table 3]

[0152] From Table 3, it is clearly indicated that the C3H2F6O+O2 gas mixture provides much better results compared to the C3H2F6+O2 gas mixture in all of the comparative parameters (SiO2 etch rate, selectivity, neck CD, and top CD). Considering that the atomic flows of elements (Ar, O, C, F, and H) were kept the same and the only difference between Examples 18 and 19 was the incorporation of oxygen into the molecule C3H2F6O in Example 18, it further proves that the use of oxygen-containing hydrofluorocarbons, and in particular the use of C3H2F6O, allows for improved etching performance in all of the critical parameters.

[0153] It will be understood that many additional changes in the details, materials, steps, and arrangements of parts that have been described and illustrated herein to explain the nature of the invention may be made by those skilled in the art within the principles and scope of the invention as set forth in the appended claims. Accordingly, the invention is not intended to be limited to the specific embodiments in the examples described above and / or in the accompanying drawings.

[0154] While embodiments of the present invention have been shown and described, modifications thereof can be made by those skilled in the art without departing from the spirit or teachings of the present invention. The embodiments described herein are illustrative only and not limiting. Many variations and modifications of compositions and methods are possible and are within the scope of the present invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the following claims, which scope is intended to encompass all equivalents of the subject matter of the claims.

Claims

1. 1. An etching method for forming apertures by selectively etching one or more silicon-containing films in a substrate using a patterned mask layer deposited on top of said one or more silicon-containing films, the method comprising: Mounting the substrate within a process chamber; introducing an etching gas containing an oxygen-containing hydrofluorocarbon vapor into the process chamber; converting the etching gas into a plasma; allowing an etching reaction to proceed 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 apertures; A method comprising:

2. The oxygen-containing hydrofluorocarbon has the general formula C ｘ H ｙ F ｚ O ｎ 2. The method of claim 1 , wherein 2≦x≦13, 1≦y≦15, 1≦z≦21, and 1≦n≦3.

3. 10. The method of claim 1, wherein the oxygen-containing hydrofluorocarbon contains at least one oxygen atom in an ether group or in a carbonyl group.

4. The oxygen-containing hydrofluorocarbon has the following formula: R １ -CO-O-CH ２ -R １ 、 R ２ -CH ２ -O-CH ２ -R ２ or R ３ -CHF-O-CF ２ -R １ (In the formula, R １ is H, F, C ｘ H ２ｘ＋２－ｚ F ｚ or C ｘ F ２ｘ＋２ and R ２ is H, C ｘ H ２ｘ＋２－ｚ F ｚ or C ｘ F ２ｘ＋２ and R ３ is F, C ｘ H ２ｘ＋２－ｚ F ｚ or C ｘ F ２ｘ＋２ where 2≦x≦3 and 1≦z≦3.

2. The method of claim 1, wherein the aryl group has at least one ether group represented by one of the following formulas:

5. The oxygen-containing hydrofluorocarbon is C ４ H ４ F ６ O.C. ４ H ２ F ６ O ２ , C ３ H ２ F ６ O.C. ２ H ２ F ４ O.C. ２ HF ３ O.C. ３ H ５ F ３ O.C. ２ H ４ F ２ O.C. ４ H ６ F ４ O.C. ５ H ４ F ８ O.C. ５ HF １１ O.C. ２ H ３ F ３ 10. The method of claim 1, wherein the aryl group is selected from the group consisting of aryl, aryloxy ...

6. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ 2. The method of claim 1, wherein the compound is O or an isomer thereof.

7. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ The method of claim 1, wherein the compound is O (CAS number: 57041-67-5).

8. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ The method according to claim 1, wherein the compound is O (CAS number: 84011-06-3).

9. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ The method according to claim 1, wherein the compound is O (CAS number: 920-66-1).

10. The etching gas is CF ４ , C ２ F ６ , C ３ F ６ , C ４ F ６ , C ４ F ８ , C ５ F ８ , C ５ F １０ , C ６ F １２ , C ７ F １４ , C ８ F １６ , C.H. ２ F ２ , C.H. ３ F, CHF ３ , C ５ HF ７ , C ３ H ２ F ６ , C ３ H ４ F ２ , C ３ F ２ H ４ , C ４ H ２ F ６ , C ４ H ３ F ７ , C ３ HF ４ N, C.F. ３ I, C ３ F ７ I, C ４ F ９ I, C ４ H ９ F ３ Si, C ５ H ９ F ５ 10. The method of claim 1, further comprising a fluorocarbon or hydrofluorocarbon vapor selected from Si or combinations thereof.

11. The etching gas is O ２ , O ３ , CO, CO ２ , SO, SO ２ , FNO, N ２ , NO, N ２ O, NO ２ , H ２ 10. The method of claim 1, further comprising an oxidizing gas selected from O, COS, or a combination thereof.

12. The method of claim 1 , wherein the etching gas further comprises an inert gas selected from He, Ar, Xe, Kr, or Ne.

13. The etching gas is H ２ , S.F. ６ , N.F. ３ , N ２ , N.H. ３ , Cl ２ , BCl ３ ,Br ２ , F ２ , HBr, HCl, PF ３ or a combination thereof.

14. The method of claim 1 , wherein the aperture has an aspect ratio greater than 5.

15. The one or more silicon-containing films are selected from silicon oxide, silicon nitride, crystalline Si, poly-silicon, amorphous silicon, low-k SiCOH, SiOCN, SiC, SiON, Si ａ O ｂ H ｃ C ｄ N ｅ 10. The method of claim 1, comprising layers of: (where a>0, b, c, d, and e≧0), or layers of alternating silicon oxide and silicon nitride (ONON) films or alternating silicon oxide and poly-silicon (OPOP) films.

16. 13. The method of claim 12, wherein the selectivity of the silicon oxide film to the silicon nitride film in the layer of ONON film is in the range of 1:5 to 5:

1.

17. 1. An etching method for forming apertures by selectively etching a silicon-containing film in a substrate using a silicon oxide film or a patterned mask layer deposited on top of said film, said method comprising: Mounting the substrate within a process chamber; Oxygen-containing hydrofluorocarbon C ３ H ２ F ６ introducing an etching gas containing O vapor into the processing chamber; converting the etching gas into a plasma; causing an etching reaction to proceed between the plasma and the silicon-containing film such that the silicon-containing film is selectively etched relative to the patterned mask layer to form the aperture; A method comprising:

18. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ 18. The method of claim 17, wherein the compound is O or an isomer thereof.

19. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ The method of claim 17, wherein the compound is O (CAS number: 57041-67-5).

20. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ The method according to claim 17, wherein the compound is O (CAS number: 84011-06-3).

21. The oxygen-containing hydrofluorocarbon is C ３ H ２ F ６ The method according to claim 17, wherein the compound is O (CAS number: 920-66-1).

22. The etching gas is CF ４ , C ２ F ６ , C ３ F ６ , C ４ F ６ , C ４ F ８ , C ５ F ８ , C ５ F １０ , C ６ F １２ , C ７ F １４ , C ８ F １６ , C.H. ２ F ２ , C.H. ３ F, CHF ３ , C ５ HF ７ , C ３ H ２ F ６ , C ３ H ４ F ２ , C ３ F ２ H ４ , C ４ H ２ F ６ , C ４ H ３ F ７ , C ３ HF ４ N, C.F. ３ I, C ３ F ７ I, C ４ F ９ I, C ４ H ９ F ３ Si, C ５ H ９ F ５ 20. The method of claim 17, further comprising a fluorocarbon or hydrofluorocarbon vapor selected from Si or combinations thereof.

23. The etching gas is O ２ , O ３ , CO, CO ２ , SO, SO ２ , FNO, N ２ , NO, N ２ O, NO ２ , H ２ 18. The method of claim 17, further comprising an oxidizing gas selected from O, COS, or a combination thereof.

24. 18. The method of claim 17, wherein the etching gas further comprises an inert gas selected from He, Ar, Xe, Kr, or Ne.

25. The etching gas is H ２ , S.F. ６ , N.F. ３ , N ２ , N.H. ３ , Cl ２ , BCl ３ ,Br ２ , F ２ , HBr, HCl, PF ３ or a combination thereof.

26. The method of claim 17 , wherein the aperture has an aspect ratio greater than 5.

27. 18. The method of claim 17, wherein the silicon-containing film is a silicon oxide film or a silicon nitride film.

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