WO2022244519A1 - エッチング方法及び半導体素子の製造方法 - Google Patents
エッチング方法及び半導体素子の製造方法 Download PDFInfo
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- WO2022244519A1 WO2022244519A1 PCT/JP2022/016207 JP2022016207W WO2022244519A1 WO 2022244519 A1 WO2022244519 A1 WO 2022244519A1 JP 2022016207 W JP2022016207 W JP 2022016207W WO 2022244519 A1 WO2022244519 A1 WO 2022244519A1
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- etching
- etched
- gas
- silicon nitride
- nitrosyl fluoride
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- 238000005530 etching Methods 0.000 title claims abstract description 387
- 238000000034 method Methods 0.000 title claims abstract description 66
- 239000004065 semiconductor Substances 0.000 title claims description 37
- 238000004519 manufacturing process Methods 0.000 title claims description 22
- ZEIYBPGWHWECHV-UHFFFAOYSA-N nitrosyl fluoride Chemical compound FN=O ZEIYBPGWHWECHV-UHFFFAOYSA-N 0.000 claims abstract description 80
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 70
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 70
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 49
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 44
- 229910003481 amorphous carbon Inorganic materials 0.000 claims description 29
- 239000003085 diluting agent Substances 0.000 claims description 25
- 239000000758 substrate Substances 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 7
- 239000002245 particle Substances 0.000 abstract description 30
- 239000007789 gas Substances 0.000 description 160
- 239000000463 material Substances 0.000 description 17
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 14
- 239000010703 silicon Substances 0.000 description 14
- 229910052710 silicon Inorganic materials 0.000 description 14
- 238000005259 measurement Methods 0.000 description 13
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 229910052786 argon Inorganic materials 0.000 description 8
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 5
- 239000011737 fluorine Substances 0.000 description 5
- 229910052731 fluorine Inorganic materials 0.000 description 5
- 229910052759 nickel Inorganic materials 0.000 description 5
- 230000015654 memory Effects 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- -1 silicon nitrides Chemical class 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000002033 PVDF binder Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 150000002222 fluorine compounds Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229920002493 poly(chlorotrifluoroethylene) Polymers 0.000 description 2
- 239000005023 polychlorotrifluoroethylene (PCTFE) polymer Substances 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229920002449 FKM Polymers 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 229910000792 Monel Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 229910000856 hastalloy Inorganic materials 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229910001026 inconel Inorganic materials 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 229910052743 krypton Inorganic materials 0.000 description 1
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 1
- JVJQPDTXIALXOG-UHFFFAOYSA-N nitryl fluoride Chemical class [O-][N+](F)=O JVJQPDTXIALXOG-UHFFFAOYSA-N 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229920013653 perfluoroalkoxyethylene Polymers 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical class [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
- H01L21/31116—Etching inorganic layers by chemical means by dry-etching
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K13/00—Etching, surface-brightening or pickling compositions
- C09K13/04—Etching, surface-brightening or pickling compositions containing an inorganic acid
- C09K13/08—Etching, surface-brightening or pickling compositions containing an inorganic acid containing a fluorine compound
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31144—Etching the insulating layers by chemical or physical means using masks
Definitions
- the present invention relates to an etching method and a method of manufacturing a semiconductor device.
- Nitrosyl fluoride can be used as an etching gas for etching silicon materials in the semiconductor manufacturing process.
- Patent Document 1 discloses a method of selectively etching silicon nitride over silicon oxide using an etching gas containing nitrosyl fluoride with a concentration of 0.1 to 20% by volume.
- Silicon nitride is an etching target that is to be etched by an etching gas
- silicon oxide is a non-etching target that is not to be etched by an etching gas.
- the etching When etching is performed using an etching gas with a low concentration of nitrosyl fluoride, the etching must be performed at a high temperature in order to increase the ratio of the etching rate of silicon nitride to the etching rate of silicon oxide, that is, the etching selectivity. .
- the etching temperature becomes higher, it becomes more difficult to keep the temperature of the member to be etched including the object to be etched and the object to be etched and the temperature of the etching gas uniform during etching. There was a risk that variations would occur.
- the present invention provides an etching method capable of selectively etching an etching object containing silicon nitride as compared with a non-etching object while suppressing particle generation and etching rate variations, and a semiconductor device manufacturing method. The task is to provide
- one aspect of the present invention is as follows [1] to [7].
- An etching gas containing more than 20% by volume of nitrosyl fluoride is applied to an etched member having an etching target to be etched by the etching gas and a non-etching target to be not etched by the etching gas.
- the member to be etched is a semiconductor substrate having the etching target and the non-etching target,
- an etching object containing silicon nitride can be selectively etched compared to a non-etching object while suppressing particle generation and variations in etching rate.
- the etching method according to the present embodiment includes an etching gas containing more than 20% by volume of nitrosyl fluoride, an etching target to be etched by the etching gas, and a non-etching target to be not etched by the etching gas.
- An etching step is provided for contacting the member to be etched and selectively etching the object to be etched as compared to the object not to be etched without using plasma.
- the etching target contains silicon nitride (SiN).
- the etching target containing silicon nitride reacts with the nitrosyl fluoride in the etching gas, so that the etching of the etching target progresses.
- non-etching objects such as resists and masks hardly react with nitrosyl fluoride, so etching of the non-etching objects hardly progresses. Therefore, according to the etching method according to the present embodiment, it is possible to selectively etch the etching target compared to the non-etching target (that is, high etching selectivity is obtained).
- the etching selection ratio which is the ratio of the etching rate of the object to be etched to the etching rate of the object not to be etched, can be 10 or more.
- the etching selectivity is preferably 30 or more, more preferably 50 or more.
- an etching target containing silicon nitride can be etched at a high etching rate. Furthermore, according to the etching method according to the present embodiment, the object to be etched can be etched without using plasma, so there is no need to use an expensive plasma generator for etching. Therefore, etching of the member to be etched can be performed at low cost.
- etching is performed using an etching gas containing more than 20% by volume of nitrosyl fluoride, so the etching selectivity can be increased without increasing the etching temperature. Since the etching can be performed at a low temperature, it becomes easy to keep the temperature of the member to be etched and the temperature of the etching gas uniform during etching, and the etching rate of the etching target is less likely to vary.
- etching can be performed at a low temperature, particles are less likely to occur during etching. If the etching is performed at a high temperature, particles may be generated due to wear of the members constituting the etching apparatus or excessive etching of the member to be etched. Since it can be carried out, particles are less likely to occur. Therefore, when semiconductor devices are manufactured using the etching method according to the present embodiment, the number of particles adhering to the member to be etched is small, so the production yield of semiconductor devices is high.
- particles refer to small pieces with a long axis of 1 nm or more, and usually small pieces with a long axis of 300 nm or less.
- shape of the particles is not particularly limited, and may be, for example, granular, foil-like, film-like, block-like, or the like.
- etching in the present invention refers to processing the member to be etched into a predetermined shape (for example, a three-dimensional shape) by removing part or all of the object to be etched contained in the member to be etched (for example, It means processing a film-like etching object made of silicon nitride, which the etching member has, to a predetermined film thickness), and cleaning by removing residues and deposits made of the etching object from the member to be etched.
- a predetermined shape for example, a three-dimensional shape
- the etching method according to the present embodiment can be used for manufacturing semiconductor devices. That is, the method for manufacturing a semiconductor device according to the present embodiment is a method for manufacturing a semiconductor device using the etching method according to the present embodiment, wherein the member to be etched is an etching target and a non-etching target.
- the etching method according to this embodiment can be used, for example, for manufacturing semiconductor devices such as 3D-NAND flash memory.
- semiconductor devices such as 3D-NAND flash memory.
- a through hole extending along the lamination direction and penetrating the laminate is formed (see FIG. 2).
- the silicon nitride film exposed on the inner surface of the through-hole is selectively and isotropically etched, so that the end portion of the silicon oxide film protrudes into the through-hole. can be formed.
- a process for forming a structure having such a structure can be used as the structure of a semiconductor device, and is therefore used in the manufacture of semiconductor devices such as 3D-NAND flash memory.
- the process of forming the above structure by etching has conventionally been performed using a chemical solution containing phosphoric acid or the like, but etching using an etching gas is superior to etching using a chemical solution in terms of microfabrication. Therefore, the etching method according to this embodiment can be expected to contribute to further miniaturization and higher integration of semiconductor devices.
- the etching method according to the present embodiment since etching can be performed at a low temperature, the etching method according to the present embodiment can be used, for example, for manufacturing a semiconductor device having a heat-sensitive circuit. can be done.
- CMOS Complementary Metal Oxide Semiconductor
- CMOS Complementary Metal Oxide Semiconductor
- the etching by the etching method according to this embodiment is adopted. Then, damage to the circuit due to heat is less likely to occur.
- non-etching object itself is used as the structure of a semiconductor device
- a material that does not substantially react with nitrosyl fluoride or a material that reacts extremely slowly with nitrosyl fluoride is used as the non-etching object.
- silicon oxide a specific example is silicon dioxide (SiO 2 )
- SiO 2 silicon dioxide
- Oxide oxygen
- the etching method according to this embodiment can also be used for cleaning, as described above.
- the inner surface of the chamber The deposit containing silicon nitride attached to the surface can be removed and cleaned by the etching method according to the present embodiment.
- the chamber corresponds to the member to be etched, which is a constituent element of the present invention
- the adhering substance corresponds to the object to be etched, which is a constituent element of the present invention.
- Particles are small pieces generated mainly due to wear of members constituting the etching apparatus, and may include small pieces generated due to excessive etching of the member to be etched. Therefore, the material of the particles is the material used as the material of the member constituting the etching apparatus or the material forming the member to be etched reacts and is generated during etching. Specific examples include stainless steel, nickel (Ni), alumina (Al 2 O 3 ), silicon, oxides such as yttrium (Y), fluorides, oxyfluorides, and oxynitrides.
- Deposits are the above-mentioned particles and etching residues adhering in various shapes to the side walls of the pattern formed by etching and the inner surface of the chamber, and the above-mentioned particles are also included. Therefore, the material of the deposit is a compound of silicon and at least one of nitrogen, oxygen, and fluorine, a material derived from amorphous carbon, and a material generated due to wear of members constituting the etching apparatus. , may include the material of the particles described above.
- Specific examples of compounds of silicon with at least one of nitrogen, oxygen, and fluorine include silicon nitrides, oxides, oxynitrides, nitrofluorides, and oxyfluorides.
- Specific examples of those derived from amorphous carbon include simple substance, fluoride, and trinitride of amorphous carbon.
- Specific examples of those generated due to wear of members constituting the etching apparatus are the same as particles, and oxides such as stainless steel, nickel, alumina, silicon, yttrium, fluorides, oxyfluorides, oxynitridation things, etc.
- the etching gas is a gas containing nitrosyl fluoride, but may be a gas containing only nitrosyl fluoride or a mixed gas containing nitrosyl fluoride and other types of gases.
- the etching gas is a mixed gas containing nitrosyl fluoride and other kinds of gases, the content of nitrosyl fluoride contained in the etching gas must be more than 20% by volume, but 30% by volume. % or more and 90 volume % or less, more preferably 30 volume % or more and 70 volume % or less.
- etching targets containing silicon nitride can be selectively etched compared to non-etching targets.
- the etching selection ratio which is the ratio of the etching rate of the object to be etched to the etching rate of the object not to be etched, can be 10 or more.
- a diluent gas can be used as another kind of gas that constitutes the etching gas together with the nitrosyl fluoride gas. That is, the etching gas can be a mixed gas containing nitrosyl fluoride and a diluent gas.
- an inert gas is suitable, specifically nitrogen gas (N 2 ), helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).
- N 2 nitrogen gas
- He helium
- Ne neon
- argon Ar
- Kr krypton
- Xe xenon
- At least one selected from The content of the diluent gas contained in the etching gas is not particularly limited, but may be more than 0% by volume and less than 80% by volume.
- the content of fluorine gas (F 2 ) and hydrogen fluoride (HF) contained in the etching gas is preferably 100 ppm by volume or less, more preferably 50 ppm by volume or less. It is more preferably 20 ppm by volume or less. If the content of fluorine gas and hydrogen fluoride is 100 ppm by volume or less, the etching selectivity tends to be high.
- the pressure condition of the etching step in the etching method according to the present embodiment is not particularly limited, but is preferably 0.1 Pa or more and 80 kPa or less, more preferably 100 Pa or more and 55 kPa or less, and 1.3 kPa or more. It is more preferable to set it to 40 kPa or less.
- the member to be etched can be arranged in a chamber, and etching can be performed while an etching gas is circulated in the chamber.
- the flow rate of the etching gas may be appropriately set according to the size of the chamber and the ability of the exhaust equipment to reduce the pressure in the chamber so that the pressure in the chamber is kept constant.
- the temperature condition of the etching step in the etching method according to the present embodiment is not particularly limited, but is preferably 50° C. or higher and 250° C. or lower, more preferably 60° C. or higher and 200° C. or lower, and 70° C. It is more preferable to set the temperature to 180° C. or more. If the temperature conditions are within the above range, advantages such as being able to perform etching without requiring excessive time and energy and being able to suppress variations in etching rate are likely to be obtained.
- the temperature of the temperature condition is the temperature of the member to be etched, but the temperature of the stage supporting the member to be etched, which is installed in the chamber of the etching apparatus, can also be used.
- Nitrosyl fluoride hardly reacts with non-etching objects such as silicon oxide and amorphous carbon under conditions that do not generate plasma and under temperature conditions of 250°C or less. Therefore, when the member to be etched has both an etching target and a non-etching target, the etching method according to the present embodiment can selectively etch the etching target without substantially etching the non-etching target. can be etched.
- the etching method according to the present embodiment includes a method of processing an etching target into a predetermined shape using a patterned non-etching target as a mask, and a method of processing an etching target into a predetermined shape, or a method of processing a structure having an etching target and a non-etching target. It can be used for a method of removing an object to be etched.
- the etching selectivity tends to be high.
- the etching selection ratio which is the ratio of the etching rate of the object to be etched to the etching rate of the object not to be etched, tends to be 10 or more.
- a member to be etched by the etching method according to the present embodiment has an etching target and a non-etching target, and has a portion formed of the etching target and a portion formed of the non-etching target.
- a member may be used, or a member formed of a mixture of an etching target and a non-etching target (for example, a non-etching target to which particles of the etching target are attached) may be used.
- the member to be etched may have an object other than the object to be etched and the object not to be etched.
- the shape of the member to be etched is not particularly limited, and may be, for example, plate-like, foil-like, film-like, powder-like, or block-like. Examples of the member to be etched include the semiconductor substrate described above.
- the object to be etched contains silicon nitride, but may be made of only silicon nitride, or may have a portion made only of silicon nitride and a portion made of another material. or a mixture of silicon nitride and another material (for example, silicon nitride particles adhering to another material).
- Silicon nitride refers to a compound formed substantially only of silicon and nitrogen and containing silicon and nitrogen in any ratio, and an example thereof is Si 3 N 4 .
- the purity of silicon nitride is not particularly limited, but is preferably 30% by mass or more, more preferably 60% by mass or more, and still more preferably 90% by mass or more.
- the shape of the etching object is not particularly limited, and may be, for example, plate-like, foil-like, film-like, powder-like, or block-like.
- Non-etching object does not substantially react with nitrosyl fluoride, or the reaction with nitrosyl fluoride is extremely slow, so that etching hardly progresses even if etching is performed by the etching method according to the present embodiment. is.
- the non-etching target is not particularly limited as long as it has the above properties, and examples thereof include silicon oxide and amorphous carbon. Examples of silicon oxides include silicon dioxide ( SiO2 ).
- composition ratio O/Si of oxygen atoms to silicon atoms in silicon oxide is particularly limited if silicon oxide does not substantially react with nitrosyl fluoride, or if the reaction with nitrosyl fluoride is slower than silicon nitride. However, it is preferably 0.3 or more and 5 or less, more preferably 0.5 or more and 4 or less, further preferably 1 or more and 3 or less, and 1.2 or more and 2.5 or less. It is particularly preferred to have
- the non-etching object is hardly etched by the etching method according to the present embodiment, the etching of the etching object by the etching gas can be suppressed by the non-etching object. Therefore, the non-etching target can be used as a resist or mask to suppress etching of the etching target by the etching gas.
- the patterned non-etching object is used as a resist or mask to process the etching object into a predetermined shape (for example, a film-like etching object possessed by the member to be etched). processing an object to have a predetermined film thickness), it can be suitably used for the manufacture of semiconductor devices.
- the non-etching target since the non-etching target is hardly etched, the non-etching target can suppress etching of a portion of the semiconductor element that should not be etched, and the etching will not cause the loss of the characteristics of the semiconductor element. can be prevented.
- the etching apparatus of FIG. 1 is an etching apparatus capable of performing plasmaless etching without using plasma. First, the etching apparatus shown in FIG. 1 will be described.
- the etching apparatus of FIG. 1 includes a chamber 10 in which etching is performed, a stage 11 that supports an etched member 12 to be etched inside the chamber 10, a thermometer 14 that measures the temperature of the etched member 12, and a chamber.
- An exhaust pipe 13 for discharging gas inside the chamber 10 a vacuum pump 15 provided in the exhaust pipe 13 for decompressing the inside of the chamber 10, and a pressure gauge 16 for measuring the pressure inside the chamber 10. I have.
- the etching apparatus of FIG. 1 also includes an etching gas supply unit that supplies etching gas into the chamber 10 and an analysis unit (not shown) that analyzes particles present inside the chamber 10 .
- This etching gas supply unit includes a nitrosyl fluoride gas supply unit 1 that supplies a nitrosyl fluoride gas, a diluent gas supply unit 2 that supplies a diluent gas, and a fluorine that connects the nitrosyl fluoride gas supply unit 1 and the chamber 10 . It has a nitrosyl fluoride gas supply pipe 5 and a diluent gas supply pipe 6 connecting the diluent gas supply unit 2 to an intermediate portion of the nitrosyl fluoride gas supply pipe 5 .
- the nitrosyl fluoride gas supply pipe 5 is equipped with a nitrosyl fluoride gas pressure controller 7 for controlling the pressure of the nitrosyl fluoride gas and a nitrosyl fluoride gas flow controller 3 for controlling the flow rate of the nitrosyl fluoride gas.
- the diluent gas supply pipe 6 is provided with a diluent gas pressure control device 8 that controls the pressure of the diluent gas and a diluent gas flow rate control device 4 that controls the flow rate of the diluent gas.
- the nitrosyl fluoride gas is supplied from the nitrosyl fluoride gas supply unit 1 to the nitrosyl fluoride gas supply pipe 5, whereby the nitrosyl fluoride gas is supplied.
- a nitrosyl fluoride gas is supplied to the chamber 10 through the pipe 5 for the chamber.
- the nitrosyl fluoride gas is supplied from the nitrosyl fluoride gas supply unit 1 to the nitrosyl fluoride gas supply pipe 5.
- the diluent gas is sent from the diluent gas supply unit 2 to the nitrosyl fluoride gas supply pipe 5 through the diluent gas supply pipe 6 .
- the nitrosyl fluoride gas and the diluent gas are mixed in the intermediate portion of the nitrosyl fluoride gas supply pipe 5 to form a mixed gas, and this mixed gas is supplied to the chamber 10 via the nitrosyl fluoride gas supply pipe 5. It has become so.
- the nitrosyl fluoride gas and the diluent gas may be separately supplied to the chamber 10 and mixed gas within the chamber 10 .
- the configurations of the nitrosyl fluoride gas supply unit 1 and the diluent gas supply unit 2 are not particularly limited, and may be, for example, cylinders or cylinders.
- the supply pressure of the etching gas is preferably 20 kPa or more and 1500 kPa or less, more preferably 40 kPa or more and 700 kPa or less, and even more preferably 60 kPa or more and 400 kPa or less. If the supply pressure of the etching gas is within the above range, the etching gas is smoothly supplied to the chamber 10, and the load on the parts (for example, the various devices and the piping) of the etching apparatus of FIG. 1 is small. .
- the pressure of the etching gas supplied into the chamber 10 is preferably 0.1 Pa or more and 80 kPa or less, more preferably 100 Pa or more and 55 kPa or less, and further preferably 1.3 kPa or more and 40 kPa or less. . If the pressure of the etching gas in the chamber 10 is within the above range, a sufficient etching rate can be obtained and the etching selectivity tends to be high.
- the pressure in the chamber 10 before supplying the etching gas is not particularly limited as long as it is equal to or lower than the supply pressure of the etching gas or lower than the supply pressure of the etching gas. It is preferably less than, more preferably 10 Pa or more and 20 kPa or less.
- the difference between the supply pressure of the etching gas and the pressure in the chamber 10 before supplying the etching gas is preferably 1.5 MPa or less, more preferably 0.6 MPa or less, and 0.4 MPa or less. It is even more preferable to have If the difference is within the above range, the etching gas is easily supplied to the chamber 10 smoothly.
- the supply temperature of the etching gas is preferably 0° C. or higher and 250° C. or lower.
- the temperature of the member to be etched 12 during etching is preferably 250° C. or lower. Within this temperature range, the etching of the object to be etched of the member to be etched 12 progresses smoothly, the load on the etching apparatus is small, and the life of the etching apparatus tends to be long.
- Etching processing time (hereinafter also referred to as "etching time”) can be arbitrarily set depending on how much the etching object of the etched member 12 is desired to be etched, but the production efficiency of the semiconductor device manufacturing process is taken into consideration. Then, it is preferably within 180 minutes, more preferably within 140 minutes, further preferably within 90 minutes, and particularly preferably within 60 minutes.
- the etching processing time refers to the time from the introduction of the etching gas into the chamber 10 to the exhaustion of the etching gas from the chamber 10 to finish the etching.
- the etching method according to the present embodiment can be performed using a general etching apparatus used in the semiconductor device manufacturing process, such as the etching apparatus shown in FIG. not.
- a general etching apparatus used in the semiconductor device manufacturing process such as the etching apparatus shown in FIG. not.
- the positional relationship between the nitrosyl fluoride gas supply pipe 5 and the member 12 to be etched is not particularly limited as long as the etching gas can be brought into contact with the member 12 to be etched.
- the temperature control mechanism for the member 12 to be etched may be provided directly on the stage 11, or may be provided externally.
- the chamber 10 may be heated or cooled from outside the chamber 10 with an attached temperature controller.
- the material of the etching apparatus in FIG. 1 is not particularly limited as long as it has corrosion resistance to nitrosyl fluoride and can be reduced to a predetermined pressure.
- metals such as nickel, nickel-based alloys, aluminum (Al), stainless steel, and platinum (Pt), ceramics such as alumina, and fluororesin can be used for portions that come into contact with the etching gas.
- nickel-based alloys include Inconel (registered trademark), Hastelloy (registered trademark), and Monel (registered trademark).
- fluororesins include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene/perfluoroalkoxyethylene copolymer (PFA), polyvinylidene fluoride (PVDF), Viton (registered trademark), Kalrez (registered trademark), and the like.
- Example 1 An etching apparatus having substantially the same configuration as the etching apparatus in FIG. 1 was used to etch samples to be etched. An etched sample used in Example 1 will be described. A silicon nitride film with a thickness of 1000 nm was formed on the surface of a disc-shaped silicon wafer with a diameter of 100 mm (manufactured by Seiren KST Co., Ltd.), and a disc-shaped silicon wafer with a diameter of 100 mm was formed with a thickness of 1000 nm on the surface.
- a silicon oxide film (manufactured by Seiren KST Co., Ltd.), and a disk-shaped silicon wafer with a diameter of 100 mm and a 1500 nm thick amorphous carbon film (manufactured by Seiren KST Co., Ltd.). were prepared respectively.
- a mixed gas was obtained by mixing a nitrosyl fluoride gas at a flow rate of 30 mL/min and argon at a flow rate of 60 mL/min, and this mixed gas was used as an etching gas. Then, this etching gas was supplied into the chamber at a flow rate of 90 mL/min and allowed to circulate for 10 minutes for etching.
- the pressure inside the chamber during the flow of the etching gas was set to 6.7 kPa, and the partial pressure of the nitrosyl fluoride gas was set to 2.2 kPa.
- the silicon nitride film, silicon oxide film, and amorphous carbon film of the three samples to be etched were etched.
- the heating of the stage was finished, and the inside of the chamber was replaced with argon.
- the content of hydrogen fluoride contained in the etching gas was measured using an infrared spectrophotometer Nicolet iS5 manufactured by Thermo Fisher Scientific Co., Ltd., it was less than 20 ppm by volume.
- the measurement conditions are as follows.
- Measurement temperature 60°C Measurement pressure: 0.1 MPa Window material: Calcium fluoride Accumulation times: 8 Measurement wavelength range: 1200 to 4000 cm -1 Peak wavelength used for measurement: 3877 cm -1
- the chamber is opened, the sample to be etched is taken out, the film thicknesses of the silicon nitride film, the silicon oxide film and the amorphous carbon film are measured, and the surfaces of the silicon nitride film, the silicon oxide film and the amorphous carbon film are measured. The number of particles adhering to was measured.
- the film thicknesses of the silicon nitride film, the silicon oxide film, and the amorphous carbon film were measured using an F20 film thickness measurement system manufactured by Filmetrics, Inc.
- the measurement conditions of the film thickness are as follows.
- Measurement pressure atmospheric pressure (101.3 kPa) Measurement temperature: 28°C Measurement atmosphere: air Silicon nitride measurement wavelength range: 900 to 1700 nm Measurement wavelength range of silicon oxide: 200 to 1000 nm Measurement wavelength range of amorphous carbon: 800 to 1200 nm
- the silicon nitride film, the silicon oxide film, and the amorphous carbon film For each of the silicon nitride film, the silicon oxide film, and the amorphous carbon film, subtract the film thickness after etching (unit: nm) from the film thickness before etching (unit: nm), and calculate the etching time (unit: min).
- the etching rates (unit: nm/min) of silicon nitride, silicon oxide, and amorphous carbon were calculated by dividing by . Then, the ratio (etching selectivity) of the etching rate of the etching object (silicon nitride) to the etching rate of the non-etching object (silicon oxide or amorphous carbon) was calculated. Table 1 shows the results.
- the number of particles adhering to the surface was measured using a wafer surface inspection device WM-2500 manufactured by Topcon. As a result, no particles were detected from any of the films. Table 1 shows the total number of particles adhering to the surfaces of the three films.
- Examples 2 to 8 and Comparative Examples 1 and 2 Three samples to be etched were etched in the same manner as in Example 1, except that the flow rates of nitrosyl fluoride gas and argon, the temperature of the stage, and the pressure inside the chamber were as shown in Table 1. were performed to calculate the etching rates and ratios of silicon nitride, silicon oxide, and amorphous carbon, respectively. Also, the number of particles adhering to the surfaces of the three films was measured in the same manner as in Example 1, and the total number was calculated. Table 1 shows the results.
- Example 9 The member to be etched used in Example 9 will be described with reference to FIG.
- the member to be etched in FIG. 2 has a structure in which 90 silicon nitride films 32 and 90 silicon oxide films 33 are alternately laminated on a silicon substrate 31 (in FIG. 2, 4 layers are alternately laminated for convenience). structure is shown).
- Each film thickness of the silicon nitride film 32 and the silicon oxide film 33 is 35 nm. However, only the uppermost silicon oxide film 33 has a film thickness of 70 nm.
- the member to be etched in FIG. 2 has a structure in which an amorphous carbon film 35 having a thickness of 1500 nm is further laminated on the uppermost silicon oxide film 33 .
- the silicon nitride film 32 is an etching object, and the silicon oxide film 33 and the amorphous carbon film 35 are non-etching objects.
- the member to be etched in FIG. 2 has a through-hole 34 with a diameter of 200 nm which penetrates the 90-layer silicon nitride film 32, the 90-layer silicon oxide film 33, and the one-layer amorphous carbon film 35 in the stacking direction. .
- the member to be etched was placed on the stage of an etching apparatus having substantially the same configuration as the etching apparatus of FIG. 1, and the temperature of the stage was set to 150.degree.
- a mixed gas was obtained by mixing a nitrosyl fluoride gas at a flow rate of 35 mL/min and argon at a flow rate of 65 mL/min, and this mixed gas was used as an etching gas.
- this etching gas was supplied into the chamber and allowed to circulate for 10 minutes to perform etching.
- the pressure inside the chamber during the flow of the etching gas was set to 6.7 kPa. When the flow of the etching gas was finished, the heating of the stage was stopped and the inside of the chamber was replaced with argon.
- the chamber was opened and the member to be etched was taken out.
- the part of the silicon nitride film 32 exposed to the inner surface of the through-hole 34 is etched, and the silicon nitride film 32 is preferentially etched compared to the silicon oxide film 33, so that the through-hole is etched.
- a portion of the inner surface of 34 flared radially outward.
- the portion of the silicon oxide film 33 exposed to the inner surface of the through-hole 34 is more difficult to etch than the silicon nitride film 32, and the amorphous carbon film 35 is hardly etched.
- a structure was formed in which the portion protruded into the through hole 34 .
- the removed member to be etched was cut, and the section of the 90-layer silicon nitride film 32 and the section of the 90-layer silicon oxide film 33 were analyzed with a transmission electron microscope. More specifically, for each of the 90 layers of the silicon nitride film 32, the gap between the portion of the silicon nitride film 32 exposed to the inner surface of the through hole 34 and the portion of the amorphous carbon film 35 exposed to the inner surface of the through hole 34 Radial distance was measured. For each of the 90 layers of the silicon oxide film 33, the radial direction between the portion of the silicon oxide film 33 exposed to the inner surface of the through hole 34 and the portion of the amorphous carbon film 35 exposed to the inner surface of the through hole 34 measured the distance.
- the inner surface of the through-hole 34 expands radially outward by etching, and the radius of the through-hole 34 increases, and the difference in the radius was measured. Then, by dividing it by the etching time, the relative etching rate of silicon nitride and silicon oxide with respect to amorphous carbon was calculated. The etching rate of amorphous carbon was calculated by comparing the diameters of the through holes 34 before and after etching, but almost no change in diameter was observed.
- the average value and standard deviation of the etching rates of the 90 layers of the silicon nitride film 32 and the 90 layers of the silicon oxide film 33 are calculated, and the relative etching in the in-plane direction of the film (direction parallel to the surface of the film) is calculated.
- the uniformity of the relative etching rate was evaluated as to whether the rate varied depending on the position in the stacking direction of the films. Also, it was confirmed whether or not there was any deposit on the side wall (inner surface) of the through hole 34 . Table 2 shows the results.
- Example 10 Except that the flow rates of the nitrosyl fluoride gas and argon and the temperature of the stage were as shown in Table 2, the member to be etched was etched in the same manner as in Example 9, and the etching rate of silicon nitride and silicon oxide was measured. The average value and standard deviation of were calculated, respectively. Further, in the same manner as in Example 9, it was confirmed whether or not there was any deposit on the side wall of the through hole 34 . Table 2 shows the results.
- the etching rate of silicon nitride increases by increasing the temperature of the stage or increasing the partial pressure of nitrosyl fluoride. Moreover, the ratio of the standard deviation of the etching rate to the average value of the etching rate of silicon nitride is about 17 to 20%. It can be seen that the progress is generally uniform.
- the ratio of the standard deviation of the etching rate to the average value of the etching rate of silicon nitride is about 80%.
- those located near the bottom of the through hole 34 tend to have a lower etching rate. tended to be low.
- adhesion of deposits to the side wall of the through hole 34 was confirmed.
- a structure in which the end of the silicon oxide film protrudes into the through-hole can be formed.
- a structure is used, for example, as the structure of a semiconductor device such as a 3D-NAND flash memory. That is, the present invention has technical significance in that it can be used for manufacturing semiconductor devices such as 3D-NAND flash memories.
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Abstract
Description
しかしながら、エッチング温度が高温になるほど、エッチング対象物及び非エッチング対象物を有する被エッチング部材の温度やエッチングガスの温度をエッチング中に均一に保つことが困難になるため、エッチング対象物のエッチング速度にバラツキが生じるおそれがあった。
本発明は、パーティクルの発生とエッチング速度のバラツキを抑えつつ、窒化ケイ素を含有するエッチング対象物を非エッチング対象物に比べて選択的にエッチングすることができるエッチング方法、及び、半導体素子の製造方法を提供することを課題とする。
[1] フッ化ニトロシルを20体積%超過含有するエッチングガスを、前記エッチングガスによるエッチングの対象であるエッチング対象物と前記エッチングガスによるエッチングの対象ではない非エッチング対象物とを有する被エッチング部材に接触させ、プラズマを用いずに、前記非エッチング対象物に比べて前記エッチング対象物を選択的にエッチングするエッチング工程を備え、前記エッチング対象物が窒化ケイ素を含有するエッチング方法。
[3] 前記エッチングガスが、フッ化ニトロシルのみからなるガス、又は、フッ化ニトロシルと希釈ガスを含有する混合ガスである[1]又は[2]に記載のエッチング方法。
[4] 前記非エッチング対象物が酸化ケイ素及びアモルファスカーボンの少なくとも一方である[1]~[3]のいずれか一項に記載のエッチング方法。
[6] 前記非エッチング対象物のエッチング速度に対する前記エッチング対象物のエッチング速度の比であるエッチング選択比が10以上である[1]~[5]のいずれか一項に記載のエッチング方法。
前記被エッチング部材が、前記エッチング対象物及び前記非エッチング対象物を有する半導体基板であり、
前記半導体基板から前記エッチング対象物の少なくとも一部を前記エッチングにより除去する処理工程を備える半導体素子の製造方法。
例えば、非エッチング対象物のエッチング速度に対するエッチング対象物のエッチング速度の比であるエッチング選択比を、10以上とすることができる。エッチング選択比は、30以上であることが好ましく、50以上であることがより好ましい。
さらに、本実施形態に係るエッチング方法によれば、プラズマを用いることなくエッチング対象物をエッチングすることができるので、高価なプラズマ発生装置を用いてエッチングを行う必要がない。そのため、被エッチング部材のエッチングを低コストで行うことができる。
エッチングを低温で実施することができるため、被エッチング部材の温度やエッチングガスの温度をエッチング中に均一に保つことが容易となり、エッチング対象物のエッチング速度にバラツキが生じにくい。
また、本発明における「エッチング」とは、被エッチング部材が含有するエッチング対象物の一部又は全部を除去して被エッチング部材を所定の形状(例えば三次元形状)に加工すること(例えば、被エッチング部材が有する、窒化ケイ素からなる膜状のエッチング対象物を所定の膜厚に加工すること)を意味するとともに、エッチング対象物からなる残留物、堆積物を被エッチング部材から除去してクリーニングすることなどを意味する。
〔エッチングガス〕
エッチングガスは、フッ化ニトロシルを含有するガスであるが、フッ化ニトロシルのみからなるガスでもよいし、フッ化ニトロシルと他種のガスとを含有する混合ガスでもよい。エッチングガスがフッ化ニトロシルと他種のガスを含有する混合ガスである場合には、エッチングガス中に含有されるフッ化ニトロシルの含有量は、20体積%超過である必要があるが、30体積%以上90体積%以下であることが好ましく、30体積%以上70体積%以下であることがより好ましい。
希釈ガスとしては、不活性ガスが好適であり、具体的には、窒素ガス(N2)、ヘリウム(He)、ネオン(Ne)、アルゴン(Ar)、クリプトン(Kr)、及びキセノン(Xe)から選ばれる少なくとも一種が挙げられる。
エッチングガス中に含有される希釈ガスの含有量は、特に限定されるものではないが、0体積%超過80体積%未満とすることができる。
本実施形態に係るエッチング方法におけるエッチング工程の圧力条件は特に限定されるものではないが、0.1Pa以上80kPa以下とすることが好ましく、100Pa以上55kPa以下とすることがより好ましく、1.3kPa以上40kPa以下とすることがさらに好ましい。
本実施形態に係るエッチング方法におけるエッチング工程の温度条件は特に限定されるものではないが、50℃以上250℃以下とすることが好ましく、60℃以上200℃以下とすることがより好ましく、70℃以上180℃以下とすることがさらに好ましい。温度条件が上記の範囲内であれば、過大な時間とエネルギーを要することなくエッチングを行うことができる、エッチング速度のバラツキを抑制することができる等の利点が得られやすい。ここで、温度条件の温度とは、被エッチング部材の温度であるが、エッチング装置のチャンバー内に設置された、被エッチング部材を支持するステージの温度を使用することもできる。
本実施形態に係るエッチング方法によりエッチングする被エッチング部材は、エッチング対象物と非エッチング対象物を有するが、エッチング対象物で形成されている部分と非エッチング対象物で形成されている部分とを有する部材でもよいし、エッチング対象物と非エッチング対象物の混合物で形成されている部材(例えば、非エッチング対象物にエッチング対象物の粒子が付着したもの)でもよい。また、被エッチング部材は、エッチング対象物、非エッチング対象物以外のものを有していてもよい。
また、被エッチング部材の形状は特に限定されるものではなく、例えば、板状、箔状、膜状、粉末状、塊状であってもよい。被エッチング部材の例としては、前述した半導体基板が挙げられる。
エッチング対象物は窒化ケイ素を含有するが、窒化ケイ素のみで形成されているものであってもよいし、窒化ケイ素のみで形成されている部分と他の材質で形成されている部分とを有するものであってもよいし、窒化ケイ素と他の材質の混合物で形成されているもの(例えば、他の材質のものに窒化ケイ素の粒子が付着したもの)であってもよい。
また、エッチング対象物の形状は、特に限定されるものではなく、例えば、板状、箔状、膜状、粉末状、塊状であってもよい。
非エッチング対象物は、フッ化ニトロシルと実質的に反応しないか、又は、フッ化ニトロシルとの反応が極めて遅いため、本実施形態に係るエッチング方法によりエッチングを行っても、エッチングがほとんど進行しないものである。非エッチング対象物は、上記のような性質を有するならば特に限定されるものではないが、例えば、酸化ケイ素、アモルファスカーボンが挙げられる。酸化ケイ素の例としては、二酸化ケイ素(SiO2)が挙げられる。
エッチングを行う際の被エッチング部材12の温度は、250℃以下とすることが好ましい。この温度範囲内であれば、被エッチング部材12が有するエッチング対象物のエッチングが円滑に進行するとともに、エッチング装置に対する負荷が小さく、エッチング装置の寿命が長くなりやすい。
例えば、フッ化ニトロシルガス供給用配管5と被エッチング部材12との位置関係は、エッチングガスを被エッチング部材12に接触させることができるならば、特に限定されない。また、チャンバー10の温度調節機構の構成についても、被エッチング部材12の温度を任意の温度に調節できればよいので、ステージ11上に被エッチング部材12の温度調節機構を直接備える構成でもよいし、外付けの温度調節器でチャンバー10の外側からチャンバー10に加温又は冷却を行ってもよい。
(実施例1)
図1のエッチング装置と略同様の構成を有するエッチング装置を用いて、被エッチングサンプルのエッチングを行った。実施例1において用いた被エッチングサンプルについて説明する。直径100mmの円板状のシリコンウエハの表面上に膜厚1000nmの窒化ケイ素膜を成膜したもの(セーレンKST株式会社製)、直径100mmの円板状のシリコンウエハの表面上に膜厚1000nmの酸化ケイ素膜を成膜したもの(セーレンKST株式会社製)、及び、直径100mmの円板状のシリコンウエハの表面上に膜厚1500nmのアモルファスカーボン膜を成膜したもの(セーレンKST株式会社製)をそれぞれ用意した。
なお、エッチングガス中に含有されるフッ化水素の含有量を、サーモフィッシャーサイエンティフィック株式会社製の赤外分光光度計Nicolet iS5を用いて測定したところ、20体積ppm未満であった。測定条件は以下のとおりである。
測定圧力:0.1MPa
窓材 :フッ化カルシウム
積算回数:8回
測定波長領域:1200~4000cm-1
測定に使用したピークの波長:3877cm-1
窒化ケイ素膜、酸化ケイ素膜、及びアモルファスカーボン膜の膜厚は、フィルメトリクス株式会社製のF20膜厚測定システムを用いて測定した。なお、膜厚の測定条件は以下のとおりである。
測定温度:28℃
測定雰囲気:大気
窒化ケイ素の測定波長領域:900~1700nm
酸化ケイ素の測定波長領域:200~1000nm
アモルファスカーボンの測定波長領域:800~1200nm
フッ化ニトロシルガス及びアルゴンの流量と、ステージの温度と、チャンバーの内部の圧力を、表1に示すとおりとした点を除いては、実施例1と同様にして3種の被エッチングサンプルのエッチングを行って、窒化ケイ素、酸化ケイ素、及びアモルファスカーボンのエッチング速度及びその比をそれぞれ算出した。また、実施例1と同様にして3つの膜の表面に付着しているパーティクルの個数を測定し、その合計数を算出した。結果を表1に示す。
実施例9において用いた被エッチング部材について、図2を参照しながら説明する。図2の被エッチング部材は、シリコン基板31上に窒化ケイ素膜32と酸化ケイ素膜33が交互に90層ずつ積層した構造を有している(図2においては、便宜上、交互に4層ずつ積層した構造を示してある。)。窒化ケイ素膜32及び酸化ケイ素膜33の膜厚は、いずれも1層あたり35nmである。ただし、最上層の酸化ケイ素膜33のみ、膜厚は70nmである。
フッ化ニトロシルガス及びアルゴンの流量とステージの温度を表2に示すとおりとした点を除いては、実施例9と同様にして被エッチング部材のエッチングを行って、窒化ケイ素及び酸化ケイ素のエッチング速度の平均値及び標準偏差をそれぞれ算出した。また、実施例9と同様にして、貫通孔34の側壁に付着物の付着があるか否か確認した。結果を表2に示す。
フッ化ニトロシルガス及びアルゴンの流量とステージの温度を表2に示すとおりとした点と、エッチングガスの流通時間を30分間とした点を除いては、実施例9と同様にして被エッチング部材のエッチングを行って、窒化ケイ素及び酸化ケイ素のエッチング速度の平均値及び標準偏差をそれぞれ算出した。また、実施例9と同様にして、貫通孔34の側壁に付着物の付着があるか否か確認した。結果を表2に示す。
実施例5、6、7の結果から、ステージの温度が高くなると窒化ケイ素のエッチング速度が速くなることが分かる。一方で、ステージの温度が50℃になると窒化ケイ素のエッチング速度が低下することから、工程のスループットを向上させるためには、エッチング温度は50℃以上とすることが好ましいことが分かる。
比較例2の結果から、エッチングガス中のフッ化ニトロシルの分圧を低くすると、窒化ケイ素のエッチング速度や酸化ケイ素に対する窒化ケイ素のエッチング選択比が低下することが分かる。これに対して、窒化ケイ素のエッチング速度を上げるためにエッチング温度を上げた比較例1では、パーティクルの発生が顕著に増加することが分かる。
2・・・希釈ガス供給部
3・・・フッ化ニトロシルガス流量制御装置
4・・・希釈ガス流量制御装置
5・・・フッ化ニトロシルガス供給用配管
6・・・希釈ガス供給用配管
7・・・フッ化ニトロシルガス圧力制御装置
8・・・希釈ガス圧力制御装置
10・・・チャンバー
11・・・ステージ
12・・・被エッチング部材
13・・・排気用配管
14・・・温度計
15・・・真空ポンプ
16・・・圧力計
31・・・シリコン基板
32・・・窒化ケイ素膜
33・・・酸化ケイ素膜
34・・・貫通孔
35・・・アモルファスカーボン膜
Claims (7)
- フッ化ニトロシルを20体積%超過含有するエッチングガスを、前記エッチングガスによるエッチングの対象であるエッチング対象物と前記エッチングガスによるエッチングの対象ではない非エッチング対象物とを有する被エッチング部材に接触させ、プラズマを用いずに、前記非エッチング対象物に比べて前記エッチング対象物を選択的にエッチングするエッチング工程を備え、前記エッチング対象物が窒化ケイ素を含有するエッチング方法。
- 前記エッチングガスがフッ化ニトロシルを30体積%以上含有する請求項1に記載のエッチング方法。
- 前記エッチングガスが、フッ化ニトロシルのみからなるガス、又は、フッ化ニトロシルと希釈ガスを含有する混合ガスである請求項1又は請求項2に記載のエッチング方法。
- 前記非エッチング対象物が酸化ケイ素及びアモルファスカーボンの少なくとも一方である請求項1~3のいずれか一項に記載のエッチング方法。
- エッチング工程の温度条件が50℃以上250℃以下である請求項4に記載のエッチング方法。
- 前記非エッチング対象物のエッチング速度に対する前記エッチング対象物のエッチング速度の比であるエッチング選択比が10以上である請求項1~5のいずれか一項に記載のエッチング方法。
- 請求項1~6のいずれか一項に記載のエッチング方法を用いて半導体素子を製造する半導体素子の製造方法であって、
前記被エッチング部材が、前記エッチング対象物及び前記非エッチング対象物を有する半導体基板であり、
前記半導体基板から前記エッチング対象物の少なくとも一部を前記エッチングにより除去する処理工程を備える半導体素子の製造方法。
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JP2005101583A (ja) * | 2003-08-29 | 2005-04-14 | Toshiba Corp | 成膜装置のクリーニング方法および成膜装置 |
JP2021509538A (ja) * | 2017-12-29 | 2021-03-25 | レール・リキード−ソシエテ・アノニム・プール・レテュード・エ・レクスプロワタシオン・デ・プロセデ・ジョルジュ・クロード | 3D NANDデバイスアプリケーションのための非プラズマ乾式処理によるSiO2に対するSiN選択的エッチング |
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JP2005101583A (ja) * | 2003-08-29 | 2005-04-14 | Toshiba Corp | 成膜装置のクリーニング方法および成膜装置 |
JP2021509538A (ja) * | 2017-12-29 | 2021-03-25 | レール・リキード−ソシエテ・アノニム・プール・レテュード・エ・レクスプロワタシオン・デ・プロセデ・ジョルジュ・クロード | 3D NANDデバイスアプリケーションのための非プラズマ乾式処理によるSiO2に対するSiN選択的エッチング |
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