USRE40748E1 - Process for producing semiconductor device - Google Patents
Process for producing semiconductor device Download PDFInfo
- Publication number
- USRE40748E1 USRE40748E1 US10/954,148 US95414804A USRE40748E US RE40748 E1 USRE40748 E1 US RE40748E1 US 95414804 A US95414804 A US 95414804A US RE40748 E USRE40748 E US RE40748E
- Authority
- US
- United States
- Prior art keywords
- film
- forming
- mask
- level dielectric
- pattern
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims abstract description 141
- 230000008569 process Effects 0.000 title claims abstract description 93
- 239000004065 semiconductor Substances 0.000 title claims abstract description 56
- 238000005530 etching Methods 0.000 claims abstract description 152
- 239000000463 material Substances 0.000 claims abstract description 38
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 30
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 29
- 239000011347 resin Substances 0.000 abstract description 41
- 229920005989 resin Polymers 0.000 abstract description 41
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 abstract description 37
- 229910052731 fluorine Inorganic materials 0.000 abstract description 37
- 239000011737 fluorine Substances 0.000 abstract description 37
- 239000010410 layer Substances 0.000 description 59
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 52
- 229910052814 silicon oxide Inorganic materials 0.000 description 37
- 239000000758 substrate Substances 0.000 description 36
- 229910052751 metal Inorganic materials 0.000 description 30
- 239000002184 metal Substances 0.000 description 30
- 239000007789 gas Substances 0.000 description 26
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 16
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 16
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 12
- 238000010586 diagram Methods 0.000 description 11
- 239000003989 dielectric material Substances 0.000 description 11
- 230000001939 inductive effect Effects 0.000 description 11
- 229920000620 organic polymer Polymers 0.000 description 11
- 238000002161 passivation Methods 0.000 description 11
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 11
- 238000004528 spin coating Methods 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 230000004888 barrier function Effects 0.000 description 9
- 238000013461 design Methods 0.000 description 9
- 229910052786 argon Inorganic materials 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000001459 lithography Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 8
- 239000000377 silicon dioxide Substances 0.000 description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 7
- 229910021529 ammonia Inorganic materials 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 229910052802 copper Inorganic materials 0.000 description 7
- 239000010949 copper Substances 0.000 description 7
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 7
- 239000004810 polytetrafluoroethylene Substances 0.000 description 7
- 230000002829 reductive effect Effects 0.000 description 7
- XPDWGBQVDMORPB-UHFFFAOYSA-N Fluoroform Chemical compound FC(F)F XPDWGBQVDMORPB-UHFFFAOYSA-N 0.000 description 6
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 238000005229 chemical vapour deposition Methods 0.000 description 6
- 230000003247 decreasing effect Effects 0.000 description 6
- 230000006866 deterioration Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 230000001965 increasing effect Effects 0.000 description 6
- 238000001020 plasma etching Methods 0.000 description 6
- 229920000090 poly(aryl ether) Polymers 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 238000004380 ashing Methods 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 229910000765 intermetallic Inorganic materials 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- -1 silicon oxide nitride Chemical class 0.000 description 5
- 238000004544 sputter deposition Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 4
- 239000004809 Teflon Substances 0.000 description 4
- 229920006362 Teflon® Polymers 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 210000003254 palate Anatomy 0.000 description 4
- 229920001721 polyimide Polymers 0.000 description 4
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical class [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 239000004642 Polyimide Substances 0.000 description 3
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 3
- YLNSPKBLFZKTHJ-UHFFFAOYSA-L [Si+2]=O.[F-].[F-] Chemical compound [Si+2]=O.[F-].[F-] YLNSPKBLFZKTHJ-UHFFFAOYSA-L 0.000 description 3
- PZPGRFITIJYNEJ-UHFFFAOYSA-N disilane Chemical compound [SiH3][SiH3] PZPGRFITIJYNEJ-UHFFFAOYSA-N 0.000 description 3
- 230000009977 dual effect Effects 0.000 description 3
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 229960001730 nitrous oxide Drugs 0.000 description 3
- 235000013842 nitrous oxide Nutrition 0.000 description 3
- 239000007800 oxidant agent Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000000059 patterning Methods 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 150000004756 silanes Chemical class 0.000 description 3
- SCPYDCQAZCOKTP-UHFFFAOYSA-N silanol Chemical compound [SiH3]O SCPYDCQAZCOKTP-UHFFFAOYSA-N 0.000 description 3
- VEDJZFSRVVQBIL-UHFFFAOYSA-N trisilane Chemical compound [SiH3][SiH2][SiH3] VEDJZFSRVVQBIL-UHFFFAOYSA-N 0.000 description 3
- 229910018503 SF6 Inorganic materials 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 2
- 125000003277 amino group Chemical group 0.000 description 2
- 229910003481 amorphous carbon Inorganic materials 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 2
- 150000008378 aryl ethers Chemical class 0.000 description 2
- 239000012159 carrier gas Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 150000002170 ethers Chemical class 0.000 description 2
- 229920002313 fluoropolymer Polymers 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- WMIYKQLTONQJES-UHFFFAOYSA-N hexafluoroethane Chemical compound FC(F)(F)C(F)(F)F WMIYKQLTONQJES-UHFFFAOYSA-N 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005121 nitriding Methods 0.000 description 2
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- MZLGASXMSKOWSE-UHFFFAOYSA-N tantalum nitride Chemical compound [Ta]#N MZLGASXMSKOWSE-UHFFFAOYSA-N 0.000 description 2
- FAQYAMRNWDIXMY-UHFFFAOYSA-N trichloroborane Chemical compound ClB(Cl)Cl FAQYAMRNWDIXMY-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 235000010627 Phaseolus vulgaris Nutrition 0.000 description 1
- 244000046052 Phaseolus vulgaris Species 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001804 chlorine Chemical class 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- WRQGPGZATPOHHX-UHFFFAOYSA-N ethyl 2-oxohexanoate Chemical compound CCCCC(=O)C(=O)OCC WRQGPGZATPOHHX-UHFFFAOYSA-N 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- UIUXUFNYAYAMOE-UHFFFAOYSA-N methylsilane Chemical compound [SiH3]C UIUXUFNYAYAMOE-UHFFFAOYSA-N 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 229920000052 poly(p-xylylene) Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 description 1
- 229960000909 sulfur hexafluoride Drugs 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
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Classifications
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- 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
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76835—Combinations of two or more different dielectric layers having a low dielectric constant
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- 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
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02118—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC
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- 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
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02118—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC
- H01L21/0212—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC the material being fluoro carbon compounds, e.g.(CFx) n, (CHxFy) n or polytetrafluoroethylene
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- 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
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
- H01L21/02126—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
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- H—ELECTRICITY
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- 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
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/022—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides
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- 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
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02203—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being porous
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- 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
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
- H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
- H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
- H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
- H01L21/02274—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]
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- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
- H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
- H01L21/02282—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
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- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02296—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer
- H01L21/02299—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer pre-treatment
- H01L21/02304—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer pre-treatment formation of intermediate layers, e.g. buffer layers, layers to improve adhesion, lattice match or diffusion barriers
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- 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
- H01L21/31127—Etching organic layers
- H01L21/31133—Etching organic layers by chemical means
- H01L21/31138—Etching organic layers by chemical means by dry-etching
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- 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
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- 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
- H01L21/312—Organic layers, e.g. photoresist
- H01L21/3127—Layers comprising fluoro (hydro)carbon compounds, e.g. polytetrafluoroethylene
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- 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
- H01L21/314—Inorganic layers
- H01L21/316—Inorganic layers composed of oxides or glassy oxides or oxide based glass
- H01L21/31695—Deposition of porous oxides or porous glassy oxides or oxide based porous glass
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76802—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics
- H01L21/76807—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics for dual damascene structures
- H01L21/76808—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics for dual damascene structures involving intermediate temporary filling with material
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76802—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics
- H01L21/76807—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics for dual damascene structures
- H01L21/76811—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics for dual damascene structures involving multiple stacked pre-patterned masks
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- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76802—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics
- H01L21/76807—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics for dual damascene structures
- H01L21/76813—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics for dual damascene structures involving a partial via etch
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76829—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
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- H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
- H01L2221/10—Applying interconnections to be used for carrying current between separate components within a device
- H01L2221/1005—Formation and after-treatment of dielectrics
- H01L2221/101—Forming openings in dielectrics
- H01L2221/1015—Forming openings in dielectrics for dual damascene structures
- H01L2221/1031—Dual damascene by forming vias in the via-level dielectric prior to deposition of the trench-level dielectric
Definitions
- the present invention relates to a process for producing a semiconductor device, and more particularly, it relates to a process for producing a semiconductor device having a multi-layer wiring structure used for device process beyond the design rule of 0.25 ⁇ m.
- An organic polymer is receiving attention as the material for the inter level dielectric having a low dielectric constant.
- An organic polymer has a dielectric constant of about 2.7, which is lower than the conventional inter level dielectric using silicon oxide (SiO 2 ) having a dielectric constant of about 4.0 and silicon oxide fluoride (SiOF) having a dielectric constant of about 3.5. Therefore, a great improvement in performance is expected in a semiconductor device using an organic polymer in an inter level dielectric.
- the organic polymer is an expensive material, taking the balance between increase in cost and improvement in performance of the semiconductor device into consideration, it has been studied a structure, in which only the inter level dielectric having groove wiring formed therein is formed with the organic polymer, and the inter level dielectric having a via hole formed therein is formed with silicon oxide or silicon oxide fluoride, which has been conventionally used.
- An example of such a structure will be described below with reference to FIGS. 1A to 1 F.
- a passivation film 111 comprising a material, into which a wiring material is not diffused, is formed with a silicon nitride film on a substrate 110 , in which transistors and wiring have been formed, and then a first inter level dielectric 112 , in which a via hole is to be formed, is formed with a silicon oxide film having a thickness of 500 nm.
- a resist mask (not shown in the figure) for forming a via hole is formed on the first inter level dielectric 112 , and a via hole 113 is formed in the first inter level dielectric 112 by etching using the resist mask as an etching mask. The resist mask is then removed.
- a second inter level dielectric 114 is formed with an organic polymer having a thickness of 500 nm on the first inter level dielectric 112 .
- a mask layer 115 to be an etching mask for forming a wiring groove is formed with a silicon oxide film having a thickness of 100 nm on the second inter level dielectric 114 .
- a resist mask 116 for forming a wiring groove pattern is formed on the mask layer 115 .
- An opening 117 for forming the wiring groove pattern is formed in the resist mask 116 .
- the wiring groove pattern 118 is formed in the mask layer 115 by etching using the resist mask 116 as an etching mask.
- the second inter level dielectric 114 is etched by using the resist mask 116 (see FIG. 1D ) and the mask layer 115 as an etching mask to form a wiring groove 119 , and the second inter level dielectric 114 filled in the via hole 113 is selectively removed to re-open the via hole 113 in the first inter level dielectric 112 .
- the resist mask 116 is simultaneously etched and removed. Therefore, a step of removing the resist mask 116 is not necessary.
- the passivation film 111 exposed at the bottom of the via hole 113 is etched by using the first and second inter level dielectrics 112 and 114 as a mask.
- the wiring groove 119 and the via hole 113 having a dual damascene structure are formed.
- the scale down of the wiring width and reduction of the interval bring about not only the aspect ratio of the wiring itself, but also the aspect ratio of the space among the wiring, and as a result, and thus difficulties are caused in the techniques for forming narrow and long wiring and the technique for filling a gap among fine wiring with an inter level dielectric.
- the process becomes complicated, and simultaneously the number of steps contained in the process is increased.
- CMP chemical mechanical polishing
- An inter layer dielectric having a low dielectric constant is applied to a device of a 0.18 ⁇ m or lower design role rule since it reduces the capacitance among the wiring.
- a film having a specific inductive capacity of 2.5 or less has a film property that is greatly different from a silicon oxide film used in the conventional device, and thus a process technique that can be applied to the film having a low dielectric constant is demanded.
- the films having a low dielectric constant of 3.0 or lower are organic films containing carbon, and they are employed instead of the conventional inter level dielectric. Oxygen is necessarily used on opening a via hole in the organic film used as the inter level dielectric.
- a resist comprising an organic film is used in the patterning technique used in the conventional process for producing a semiconductor device, there is a problem in that the film having a low dielectric constant is damaged in the step of removing the resist. Because the composition of the film having a low dielectric constant is similar to the composition of the resist, there is a possibility that the film having a low dielectric constant is removed in the step of removing the resist.
- xerogel In recent years, an application of xerogel to a semiconductor device is receiving attention as a material expected to have a specific inductive capacity of 2.0 or less.
- the xerogel is a well-known material, for example, as silica gel used as a desiccating agent.
- the application of xerogel to a semiconductor device is difficult at present due to a demand of various kinds of reliability. That is, xerogel contains from 50 to 90% of pores by volume and thus has a problem in mechanical strength.
- the second inter level dielectric is filled in the via hole in the step shown in FIG. 1 B. Therefore, in the step shown in FIG. 1E , because the second inter level dielectric in the via hole is etched until it is completely removed, over etching is often applied to the bottom of the wiring groove and the mask layer. As a result, the shoulder parts of the bottom of the wiring groove and the mask layer are cut by a sputtering phenomenon, and a wiring groove and a via hole having a good shape are difficult to be obtained. In the case where the interval of the wiring grooves is narrow, the wiring grooves adjacent to each other are connected due to the cutting of the shoulder parts of the mask layer, so as to cause a defect such as a short circuit.
- a first inter level dielectric 112 is formed, and then a via hole 113 is formed in the first inter level dielectric 112 , as shown in FIG. 2 A.
- a second inter level dielectric 114 filling the via hole 113 is formed on the first inter level dielectric 112 .
- a resist mask 116 for forming a wiring groove pattern is formed on the mask layer 115 .
- An opening 117 for forming the wiring groove pattern is formed in the resist mask 116 . At this time, it is assumed that the opening 117 is formed deviating from the via hole 113 due to misalignment.
- a wiring groove pattern 118 is formed in the mask layer 115 by etching using the resist mask 116 as an etching mask.
- the second inter level dielectric 114 is etched by using the resist mask 116 (see FIG. 2D ) and the mask layer 115 as an etching mask to form a wiring groove 119 , and the second inter level dielectric 114 filled in the via hole 113 is selectively removed to re-open the via hole 113 in the first inter level dielectric 112 .
- the wiring groove 119 is formed deviating from the via hole 113 due to the misalignment, the second inter level dielectric 114 remains in a part of the via hole 113 to stuff up a part of the via hole 113 , and thus the opening area is decreased.
- the passivation film 111 exposed at the bottom of the via hole 113 is etched by using the first and second inter level dielectrics 112 and 114 as a mask.
- the wiring groove 119 and the via hole 113 having a dual damascene structure are formed as described in the foregoing, because a part of the via hole 113 is stuffed up by the second inter level dielectric 114 , the contact area becomes small to cause increase in contact resistance.
- An object of the invention is to provide a process for producing a semiconductor device for solving the problems described in the foregoing.
- the invention relates to a process for producing a semiconductor device comprising an inter level dielectric comprising a xerogel film or an organic film, the process comprising a step of forming, on an inter level dielectric, a first mask to be an etching mask for etching the inter level dielectric; and a step of forming, on the first mask, a second mask comprising a different material from the first mask to be an etching mask for etching the inter level dielectric.
- the process for producing a semiconductor device of the invention comprises the step of forming, on an inter level dielectric, a first mask to be an etching mask for etching the inter level dielectric; and the step of forming, on the first mask, a second mask comprising a different material from the first mask to be an etching mask for etching the inter level dielectric, after the inter level dielectric is etched by using the first mask as an etching mask, the inter level dielectric can be etched by using the second mask as an etching mask to a pattern different from the first mask.
- a lower layer of the inter level dielectric formed between wiring layers may be formed with an organic film, and an upper layer of the inter level dielectric formed between wiring of the same wiring layer may be formed with a xerogel film or an organic film.
- the dielectric constant between wiring of the same wiring layer which becomes the maximum wiring capacitance, can be about from 1.8 to 2.4, and thus the wiring capacitance can be reduced.
- a xerogel film or an organic film, such as a fluorine resin film is applied to the part where the wiring interval is 0.3 ⁇ m or less. While the wiring capacitance is generally remarkably increased at the part where the wiring interval is 0.3 ⁇ m or less, an effect of decreasing the wiring capacitance can be obtained by using the xerogel film or the organic film, such as a fluorine resin film.
- the lower layer of the inter level dielectric can be formed with an organic film, and the same function described in the foregoing can also be obtained in this case.
- a pattern for forming the wiring groove may be formed in the second mask, and a pattern for forming the via hole is formed in the first mask in such a manner that the pattern for forming the via hole at least overlaps the pattern for forming the wiring groove.
- the process for producing a semiconductor device may comprise, a step of forming, on the inter level dielectric, a first film for forming the first mask; a step of forming, on the first film, a second film for forming the second mask; a step of forming the second mask by forming a pattern or forming the wiring groove in the second film; and a step of forming the first mask by forming a pattern for forming the via hole in the first film is such a manner that the pattern for forming the via hole at least overlaps the pattern for forming the wiring groove.
- the resist process used for forming the first and second masks can be conducted under the condition in that the inter level dielectric is not exposed. That is, in the resist process for forming the second mask, the first film is formed as an underlayer, and in the resist process for forming the first mask, the first film itself covers the inter level dielectric. Thus, the restoration treatment of the resist process can be conducted.
- the pattern for forming the via hole can also be formed in the second mask, and there is no possibility that the opening area of the via hole is reduced as described with reference to FIGS. 2A to 2 F.
- the so-called mask alignment where the position of the mask is aligned to the underlayer upon exposure, can be conducted by an alignment method using light or an alignment method using an image processing.
- FIGS. 1A to 1 F are cross sectional views showing a process diagram of a production process according to the conventional technique.
- FIGS. 2A to 2 F are cross sectional views showing a process diagram of a production process according to the conventional technique where misalignment occurs.
- FIGS. 3A to 3 F, 4 G and 4 H are cross sectional views showing a process diagram of a first embodiment of the process for producing a semiconductor device according to the invention.
- FIGS. 5A to 5 C are cross sectional views showing a process diagram of a second embodiment of the process for producing a semiconductor device according to the invention.
- FIGS. 6A to 6 F are cross sectional views showing a process diagram of a third embodiment of the process for producing a semiconductor device according to the invention.
- FIGS. 7A to 7 I are cross sectional views showing a process diagram of a fourth embodiment of the process for producing a semiconductor device according to the invention.
- FIGS. 8A to 8 F are cross sectional views and plan views showing a process diagram of a fourth embodiment of the process for producing a semiconductor device according to the invention where misalignment occurs.
- FIGS. 3A to 3 F, 4 G and 4 H A first embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 3A to 3 F, 4 G and 4 H.
- an underlying substrate 11 comprises, for example, a substrate 51 having thereon transistors (not shown in the figure), and an inter metal dielectric 52 covering thereon, in which wiring 53 is formed.
- a first film having a low dielectric constant 13 to be a lower layer of an inter level dielectric 12 is formed on the underlying substrate 11 to a thickness of, for example, from 300 to 800 nm.
- the first film having a low dielectric constant 13 becomes an inter level dielectric (ILD) between wiring layers, and can be formed with an organic film having a specific inductive capacity of about 2.5.
- an organic polymer totally called as polyaryl ether is employed.
- polyaryl ether examples include flare (a tradename, produced by Aliedsignal Inc.), SILK (a trade name, produced by Dow Chemical Corp.) and VELOX (a trade name, produced by Schumacher Corp.).
- flare a tradename, produced by Aliedsignal Inc.
- SILK a trade name, produced by Dow Chemical Corp.
- VELOX a trade name, produced by Schumacher Corp.
- a BCB (bis-benzocyclobutene) film, a polyimide film and an amorphous carbon film may be used.
- the formation of the organic polymer can be conducted, for example, by a precursor is coated as a film on the underlying substrate 11 by spin coating, and then cured at a temperature of from 300 to 450° C.
- a precursor is coated as a film on the underlying substrate 11 by spin coating, and then cured at a temperature of from 300 to 450° C.
- a silicon oxide film, a silicon oxide nitride film, a silicon carbide film or a titanium nitride silicate film is formed.
- the silicon oxide film can be formed, for example, by the following manner.
- a commercially available SOG spin on glass, for example, an SOG mainly comprising silanol, and an SOG mainly comprising a polymer containing silanol
- the coated film is baked at a temperature of from 150 to 200° C. for about 1 minute, and then cured at a temperature of from 350 to 450° C. for about from 30 to 60 minutes.
- the silicon oxide film may be formed by a plasma CVD (chemical vapor deposition) method using a commercially available plasma CVD apparatus.
- a plasma CVD chemical vapor deposition
- the wiring 53 is copper wiring
- the copper wiring can be prevented from oxidation as possible by using dinitrogen monoxide (N 2 O) gas as the oxidizing agent, using a silane series gas (for example, monosilane (SiH 4 ), disilane (Si 2 H 6 ) or trisilane (Si 3 H 8 )) as the silicon source, setting the substrate temperature to 300 to 400° C., setting the plasma power to 350 W, and the pressure of the film forming environment to about 1 kPa.
- N 2 O dinitrogen monoxide
- silane series gas for example, monosilane (SiH 4 ), disilane (Si 2 H 6 ) or trisilane (Si 3 H 8 )
- a commercially available inorganic SOG containing an amino group may be, for example, by formed into a film by a spin coating method. It is preferred that the film formation is conducted by the plasma CVD method.
- the gas used in the plasma CVD method include a silane series gas (monosilane (SiH 4 ), disilane (Si 2 H 6 ) or trisilane (Si 3 H 8 )) as the silicon source, ammonia and hydrazine as the nitriding agent, and dinitrogen monoxide (N 2 O) as the oxidizing agent.
- As the carrier gas an inert gas, such as nitrogen, helium and argon, is employed.
- the film formation is conducted, for example, under such conditions that the substrate temperature is from 300 to 400° C., the plasma power is 350 W, and the pressure of the film forming environment is about 1 kPa.
- the silicon nitride film it can be formed by spin coating of a commercially available inorganic SOG containing an amino group as similar to the case of the silicon nitride oxide film. It is preferred that the film formation is conducted by the plasma CVD method.
- the gas used in the plasma CVD method include a silane series gas (monosilane (SiH 4 )), disilane (Si 2 H 6 ) or trisilane (Si 3 H 8 )) as the silicon source, ammonia and hydrazine as the nitriding agent, and dinitrogen monoxide (N 2 O) as the oxidizing agent.
- an inert gas such as nitrogen, helium and argon
- the film formation is conducted, for example, under such conditions that the substrate temperature is from 300 to 400° C., the plasma power is 350 W, and the pressure of the film forming environment is about 1 kPa.
- the silicon carbide film can be formed, for example, by using a parallel flat palate type plasma CVD apparatus.
- the gas used in the plasma CVD method include methyl silane as the silicon source.
- the film formation is conducted, for example, under such conditions that the substrate temperature is from 300 to 400° C., the plasma power is from 150 to 350 W, and the pressure of the film forming environment is about from 100 Pa to 1 kPa.
- a second film having a low dielectric constant 14 to be an upper layer of the inter level dielectric 12 is formed to a thickness, for example, of 400 nm on the first film having a low dielectric constant 13 .
- the second film having a low dielectric constant 14 is formed with a fluorine resin.
- the film include a fluorocarbon film, such as a cyclic fluorine resin, polytetrafluoroethylene (PTFE), amorphous PTFE (for example, Teflon AF, a trade name, produced by Du Pont Corp.), fluorinated aryl ether and fluorinated polyimide.
- a xerogel for example, porous silica may be employed.
- the film of the fluorine resin can be formed by the manner, in which a precursor of the fluorine resin is coated on the first film having a low dielectric constant 13 by a spin coating apparatus, and then cured at a temperature of from 300 to 450° C.
- the materials such as fluorinated amorphous carbon, can be formed by a plasma CVD method using acetylene (C 2 H 2 ) and a fluorocarbon gas (for example, octafluorobutane (C 4 F 8 )) as the process gas.
- the film thus formed is cured at a temperature of from 300 to 450° C.
- the amorphous PTFE is not limited to Teflon AF and may be any substance having the structure represented by the following formula (1): wherein m and n each represent a positive integer.
- a cyclopolymerized fluorinated polymer series resin (for example, Cytop, a trade name) may be used.
- the cyclopolymerized fluorinated polymer series resin is not limited to Cytop and may be any substance having the structure represented by the following formula (2): wherein x, y and z each represent a positive integer.
- a fluorinated polyaryl ether series resin (for example, FLARE, a trade name) may be used.
- the fluorinated polyaryl ether series resin is not limited to FLARE and may be any substance having the structure represented by the following formula (3); wherein R represents an alkyl group.
- Nanoporous Silica developed by Nanoglass LLC is formed into a film by using a spin coating apparatus developed by Nanoglass LLC.
- Nanoporous Silica is a kind of porous silica, and the xerogel that can be used in the invention is not limited to Nanoporous Silica. That is, any type of xerogels that can be formed by the following method can be used.
- a silanol resin having an alkyl group having a relatively high molecular weight, such as an aromatic group is coated on a substrate and gelled, and the film is then subjected to a hydrophobic treatment by using a silane coupling agent or a hydrogenating treatment.
- the inter level dielectric 12 comprising the first film having a low dielectric constant 13 and the second film having a low dielectric constant 14 is formed on the underlying substrate
- a first film 15 for forming a first mask as an inorganic mask is formed with a silicon oxide film having a thickness of from 50 to 300 nm on the inter level dielectric 12 , i.e., on the second film having a low dielectric constant 14 .
- a second film 16 for forming a second mask is formed with a silicon nitride film having a thickness of from 50 to 150 nm.
- an ordinary CVD apparatus is used under the same conditions as described in the foregoing.
- a film having a larger silicon content than the silicon nitride film, the amorphous silicon nitride film, the silicon oxide film or the stoichiometric amount is formed, depending on necessity, particularly in the case where the oxidation of the second film having a low dielectric constant 15 causes a problem. That is, a CVD film is formed under a reductive atmosphere.
- the film thickness is preferably as thin as possible, and is generally about 10 nm.
- the first film 15 is formed with a silicon oxide film that is excellent in light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment
- the second film 16 is also formed with a silicon nitride film having light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment.
- a metallic film or a metallic compound film such as titanium, titanium nitride, tantalum and tantalum nitride, can be used, as well as the silicon nitride film.
- the film thickness thereof is preferably from 50 to 150 nm.
- the film formation thereof can be conducted by sputtering, which is generally employed in film formation of a metallic film and a metallic compound film.
- a resist film 17 is formed on the second film 16 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 17 is patterned by a lithography technique to form openings 18 for forming wiring grooves.
- an ordinary resist coating technique for example, a spin coating method.
- the second film 16 is etched by using the resist film 17 as an etching mask to form openings 19 for forming wiring grooves, so as to form a second mask 21 to be an etching mask for forming wiring grooves in the inter level dielectric 12 .
- the second film 16 is selectively etched by using an ordinary magnetron type etching apparatus.
- the etching conditions where the second film 16 comprises a silicon nitride film for example, trifluoromethane (CHF 3 ) (5 cm 3 /min), oxygen (O 2 ) (5 cm 3 /min) and argon (Ar) (20 cm 3 /min) are used as the etching gas, and an RF plasma is set at 600 W.
- a chlorine series etching gas such as boron chloride (BCl) and chlorine (Cl 2 ) is used as the etching gas. Thereafter, the resist film 17 is removed by ashing.
- FIG. 3C shows the state before removing the resist film 17 .
- a resist film 22 is formed on the second film 16 and the first film 15 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 22 is patterned by a lithography technique to form openings 23 for forming via holes at positions within the openings 19 for forming the wiring grooves from the plan view of the second film 16 .
- an ordinary resist coating technique for example, a spin coating method.
- the first film 15 is etched by using the resist film 22 as an etching mask to form openings 24 for forming via holes in the inter level dielectric 12 , so as to form a first mask 25 to be a etching mask for forming the via holes in the inter level dielectric 12 .
- the second film having a low dielectric constant 14 of the inter level dielectric 12 is etched by using an ordinary etching apparatus using the resist film 22 as an etching mask.
- the etching conditions for example, hexafluoroethane (C 2 F 6 ) (14 cm 3 /min), carbon monoxide (180 cm 3 /min) and argon (240 cm 3 /min) are used as an etching gas, and an RF plasma is set at 1.5 kw. Because the first film having a low dielectric constant 13 comprising an organic film is present as an underlayer of the second film having a low dielectric constant 14 , the etching is stopped at the upper surface of the first film having a low dielectric constant 13 .
- the first film having a low dielectric constant 13 is etched by using an ordinary etching apparatus using the first mask 25 as an etching mask, to form via holes 26 in the inter level dielectric 12 .
- an etching gas in the etching nitrogen is used, and ammonia and a hydrogen gas are also used depending on necessity.
- the resist film 22 is also etched and completely removed. Therefore, there is no necessity to conduct resist ashing in this stage.
- the first mask 25 is etched, and then the second film having a low dielectric constant 14 is etched, so as to form wiring grooves 27 in the second film having a low dielectric constant 14 .
- the etching conditions of this step are the same as those for etching the second film having a low dielectric constant 14 described in the foregoing.
- wiring is formed by a damascene method.
- a barrier metal layer 31 comprising tantalum nitride is formed on the inner walls of the wiring grooves 27 and the via holes 26 by sputtering or by a CVD method. At this time, the barrier metal layer 31 is also formed on the second mask 21 .
- a wiring material (metal), such as copper, is accumulated by sputtering, a CVD method or an electrolytic plating method. In the case where the metal 32 is accumulated by an electrolytic plating method, a seed layer (not shown in the figure) comprising the same metal as the metal 32 to be accumulated is formed in advance.
- an excess metal 32 and the barrier metal layer 31 on the second mask 21 are removed by polishing using CMP, and, as shown in FIG. 4H , wiring 33 comprising the metal 32 is formed on the wiring grooves 27 via the barrier metal layer 31 , so as to form plugs 34 comprising the metal 32 in the via holes 26 via the barrier metal layer 31 .
- the second mask 21 functions as a polishing stopper, but in some cases, the second mask 21 may be completely removed depending on the thickness of the second mask 21 .
- this CMP for example, an alumina slurry is employed.
- the process comprising from the step of forming the inter level dielectric 12 to the step of forming the wiring 33 and the plugs 34 may be repeated to form a multi-layer wiring.
- the inter metal dielectric 52 among the wiring 53 may be formed with a xerogel film or a fluorine resin film by the similar process as the foregoing.
- the production process can be applied to the case where the inter level dielectric 12 , the via holes 26 , the wiring grooves 27 , the wiring 33 and the plugs 34 having the constitution described above are formed on a substrate having no semiconductor element.
- the process for producing a semiconductor device described in the foregoing comprises a step of forming, on the inter level dielectric 12 , the first mask 25 to be an etching mask for etching the inter level dielectric 12 , and a step of forming, on the first mask 25 , the second mask 21 to bean etching mask for etching the inter level dielectric 12 , the second mask 21 comprising a material different from the first mask 25 .
- the inter level dielectric 12 is etched by using the first mask 25 as an etching mask to form the via holes 26 , and then the upper layer of the inter level dielectric 12 , i.e., the second film having a low dielectric constant 14 , is etched by using the second mask 21 as an etching mask to a pattern for forming wiring grooves different from the first mask 25 , to form the wiring grooves 27 .
- the dielectric constant between the wirings in the same wiring layer where the wiring capacity becomes maximum is about from 1.8 to 2.4, and thus the wiring capacitance is reduced.
- a xerogel film or a fluorine resin film is applied to the part where the wiring interval is 0.3 ⁇ m or less. While the wiring capacitance is generally remarkably increased at the part where the wiring interval is 0.3 ⁇ m or less, an effect of decreasing the wiring capacitance can be obtained by using the xerogel film or the fluorine resin film.
- the resist process (a step of patterning the resist film) for forming the first and second masks 25 and 21 can be conducted under the condition where the inter level dielectric 12 is not exposed. That is, in the resist process for forming the second mask 21 , the first film 15 is formed as an underlayer, and in the resist process for forming the first mask 25 , the first film 15 itself covers the inter level dielectric 12 . Thus, without exposing the inter level dielectric 12 comprising an organic film, the resist films 17 and 22 formed by the resist process can be removed, and a restoration treatment of the resist where the resist films 17 and 22 are again formed and patterned can be conducted.
- the resist film 22 to be an etching mask for forming the first mask can be removed simultaneously to the etching of the first film having a low dielectric constant 13 , the operation of removing the resist film 22 by ashing is not necessary. Therefore, the process can be simplified.
- the openings 24 to be a pattern for forming the via holes are formed in the first mask 25 , i.e., in the process for forming the openings 23 in the resist film 22 , even when misalignment occurs to form the openings 23 formed in the resist film 22 deviating from the openings 19 to be a pattern for forming the wiring grooves, because openings (not shown in the figure) to be a pattern for forming the via holes can be formed in the second mask 21 , a via holes having a narrowed opening area is not formed as described with reference to FIGS. 2A to 2 F.
- the mask alignment where the position of the mask is aligned to the underlayer in an exposure step, can be conducted by an ordinary alignment method using light or an alignment method using an image processing. It has been known that a silicon oxide film and a silicon nitride film transmit light in the wavelength region of from 200 to 1,000 nm used for alignment.
- an etching stopper layer having a high dielectric constant for example, a silicon nitride film, a silicon oxide film or a silicon oxide nitride film
- a high dielectric constant for example, a silicon nitride film, a silicon oxide film or a silicon oxide nitride film
- the wiring grooves 27 can be formed in the second film having a low dielectric constant 14 to be a wiring layer with good controllability.
- the second film having a low dielectric constant 14 comprising a xerogel or a fluorine resin is etched, and simultaneously the first film having a low dielectric constant 13 comprising an organic film is etched.
- FIGS. 5A to 5 C A second embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 5A to 5 C.
- the same symbols are attached to the same constitutional components as in FIGS. 3A to 3 F, 4 G and 4 H.
- an underlying substrate 11 comprises, for example, a substrate 51 having thereon transistors (not shown in the figure), and an inter metal dielectric 52 covering thereon, in which wiring 53 is formed.
- a first film having a low dielectric constant 13 to be a lower layer of an inter level dielectric 12 on the underlying substrate 11 is formed, for example, with an inorganic film having a thickness of from 300 to 800 nm.
- a second film having a low dielectric constant 14 to be an upper layer of the inter level dielectric 12 is formed to a thickness, for example, of 400 nm on the first film having a low dielectric constant 13 .
- the second film having a low dielectric constant 14 is formed with a fluorine resin.
- the fluorine resin the materials described for the first embodiment can be employed.
- the inter level dielectric 12 comprising the first film having a low dielectric constant 13 and the second film having a low dielectric constant 14 is thus formed on the underlying substrate 11 .
- a first film 15 for forming a first mask as an inorganic mask is formed with a silicon oxide film having a thickness of from 50 to 300 nm on the inter level dielectric 12 , i.e., on the second film having a low dielectric constant 14 .
- a second film 16 for forming a second mask is formed with a silicon nitride film having a thickness of from 50 to 150 nm. The film forming method of these films is the same as those described for the first embodiment.
- the second film 16 is etched to form openings 19 for forming wiring grooves, so as to form a second mask 21 to be an etching mask for forming the wiring grooves in the inter level dielectric 12 .
- a resist film 22 is formed on the second film 16 and the first film 15 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 22 is patterned by a lithography technique to form openings 23 for forming via holes at positions within the openings 19 for forming the wiring grooves from the plan view of the second film 16 .
- an ordinary resist coating technique for example, a spin coating method.
- the first film 15 is etched by using the resist film 22 as an etching mask to form openings 24 for forming via holes in the inter level dielectric 12 , so as to form a first mask 25 to be an etching mask for forming the via holes in the inter level dielectric 12 .
- the second film having a low dielectric constant 14 of the inter level dielectric 12 is etched by using an ordinary etching apparatus using the first mask 25 as an etching mask.
- etching conditions for example, nitrogen (N 2 ) (48 cm 3 /min) and helium (He) (200 cm 3 /min) are used as an etching gas, a microwave power is set at 1.35 kW (2.45 GHz), an RF plasma is set at 150 W, and a substrate temperature is set at ⁇ 50° C. Because the resist film 22 is etched and completely removed in this etching step, removal of the resist is not necessarily conducted.
- the etching is stopped at the upper surface of the first film having a low dielectric constant 13 .
- the first mask 25 is then etched by using the second mask 21 comprising a silicon nitride film (or a metallic compound film).
- the second film having a low dielectric constant 14 is formed with an organic film
- the first film having a low dielectric constant 13 comprising an inorganic film is etched with the second film having a low dielectric constant 14 as an etching mask, so as to form via holes 26 .
- octafluorobutane (C 4 F 8 ) and carbon monoxide (CO), for example, are used as an etching gas.
- the second film having a low dielectric constant 14 is etched by using the second mask 21 as an etching mask to form wiring grooves 27 .
- the etching conditions in this step are the same as the conditions for etching the second film having a low dielectric constant 14 .
- the etching is stopped at the upper surface of the first film having a low dielectric constant 13 .
- wiring is formed in the wiring grooves 27 via a barrier metal layer, and plugs are formed in the via holes 26 via the barrier metal layer, in the same manner as described with reference to FIGS. 4G and 4H for the first embodiment.
- the process comprising from the step of forming the inter level dielectric 12 to the step of forming the wiring and the plugs may be repeated to form a multi-layer wiring.
- the inter metal dielectric 52 among the wiring 53 may be formed with an organic film, such as a xerogel film or a fluorine resin film, by the similar process as the foregoing.
- the production process can be applied to the case where the inter level dielectric 12 , the via holes 26 , the wiring grooves 27 , the wiring 33 and the plugs 34 having the constitution described above are formed on a substrate having no semiconductor element.
- the same function and effect as the first embodiment of the process for producing a semiconductor device can be obtained.
- FIGS. 6A to 6 F A third embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 6A to 6 F.
- the same symbols are attached to the same constitutional components as in FIGS. 3A to 3 F.
- an underlying substrater 11 comprises, for example, a substrate 51 having thereon transistors (not shown in the figure), and an inter metal dielectric 52 covering thereon, in which wiring 53 is formed.
- a first film having a low dielectric constant 13 to be a lower layer of an inter level dielectric 12 is formed to a thickness of, for example, from 300 to 800 nm on the underlying substrate 11 .
- the first film having a low dielectric constant 13 becomes an inter level dielectric (ILD) between wiring layers, and can be formed with an organic film having a specific inductive capacity of about 2.5. For example, it can be formed with the same material as described for the first embodiment in the same film forming method as described therefor.
- ILD inter level dielectric
- An intermediate film 41 to be an etching mask is formed with, for example, a silicon oxide film on the first film having a low dielectric constant 13 .
- the method for forming the same may be the same forming method of the silicon oxide film as described for the first embodiment.
- a second film having a low dielectric constant 14 to be an upper layer of the inter level dielectric 12 is formed to a thickness, for example of 400 nm on the intermediate film 41 .
- the second film having a low dielectric constant 14 is formed with a fluorine resin.
- the film include a fluorocarbon film, such as a cyclic fluorine resin, polytetrafluoroethylene (PTFE), amorphous PTFE (for example, Teflon AF, a trade name, produced by Du Pont Corp.), fluorinated aryl ether and fluorinated polyimide.
- a xerogel for example, porous silica may be employed.
- the method for forming the fluorine resin film may be the same forming method as described for the first embodiment.
- the second film having a low dielectric constant 14 is formed with a xerogel film.
- the method for forming the xerogel film may be the same forming method as described for the first embodiment.
- the inter level dielectric 12 comprising the first film having a low dielectric constant 13 , the intermediate film 41 and the second film having a low dielectric constant 14 is formed on the underlying substrate 11 .
- a first film 15 for forming a first mask as an inorganic mask is formed with a silicon oxide film having a thickness of from 50 to 300 nm on the inter level dielectric 12 , i.e., on the second film having a low dielectric constant 14 .
- a second film 16 for forming a second mask is formed with a silicon nitride film having a thickness of from 50 to 150 nm.
- the film forming method of these films may be the same forming method as described for the first embodiment.
- a film having a larger silicon content than the silicon nitride film, the amorphous silicon, the silicon nitride oxide film or the stoichiometric amount is formed, depending on necessity, particularly in the case where the oxidation of the second film having a low dielectric constant 15 causes a problem. That is, a CVD film is formed under a reductive atmosphere.
- the film thickness is preferably as thin as possible, and is generally about 10 nm.
- the first film 15 is formed with a silicon oxide film that is excellent in light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment
- the second film 16 is also formed with a silicon nitride film having light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment.
- a resist film 17 is formed on the second film 16 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 17 is patterned by a lithography technique to form openings 18 for forming wiring grooves.
- an ordinary resist coating technique for example, a spin coating method.
- the second film 16 is etched by using the resist film 17 as an etching mask to form openings 19 for forming wiring grooves, so as to form a second mask 21 to be an etching mask for forming wiring grooves in the inter level dielectric 12 .
- the etching step may be conducted in the same manner as for the first embodiment.
- the resist film 17 is removed by ashing.
- FIG. 6C shows the state before removing the resist film 17 .
- a resist film 22 is formed on the second film 16 and the first film 15 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 22 is patterned by a lithography technique to form openings 23 for forming via holes at positions within the openings 19 for forming the wiring grooves from the plan view of the second film 16 . Even when deviation occurs on aligning the masks, it is necessary that at least a part of the opening 23 overlaps the opening 19 .
- an ordinary resist coating technique for example, a spin coating method
- the first film 15 is etched by using the resist film 22 as an etching mask to form openings 24 for forming via holes in the inter level dielectric 12 , so as to form a first mask 25 to be an etching mask for forming the via holes in the inter level dielectric 12 .
- the second film having a low dielectric constant 14 of the inter level dielectric 12 is etched by using an ordinary etching apparatus using the first mask 25 as an etching mask.
- the etching conditions for example, nitrogen is used as an etching gas, and ammonia and a hydrogen gas may also be used depending on necessity.
- a fluorine carbide series gas and carbon monoxide are not necessary. Because the intermediate film 41 comprising a silicon oxide film is present as an underlayer of the second film having a low dielectric constant 14 , the etching is stopped at the intermediate film 41 .
- the resist film 22 is etched and completely removed when the second film having a low dielectric constant 14 comprising an organic film is etched. Therefore, there is no necessity to conduct resist ashing in this stage.
- the first mask 25 and the intermediate film 41 are etched by using an ordinary etching apparatus using the second mask 21 and the second film having a low dielectric constant 14 as an etching mask. That is, the first mask 25 is etched as transferring the openings 19 formed in the second mask 21 for forming the wiring grooves, and openings 42 for forming via holes in the intermediate film 41 are formed by etching.
- the etching conditions for example, octafluorobutane (C 4 F 8 ) (5 cm 3 /min), carbon monoxide (5 cm 3 /min) and argon (20 cm 3 /min) are used as an etching gas, and an RF plasma is set at 600 W.
- the second film having a low dielectric constant 14 and the first film having a low dielectric constant 13 are etched, to form wiring grooves 27 in the second film having a low dielectric constant 14 , and simultaneously to form via holes 26 in the first film having a low dielectric constant 13 .
- the etching gas in this etching step nitrogen (N 2 ) is used, and ammonia and a hydrogen gas may also be used depending on necessity.
- wiring comprising metal is formed in the wiring grooves 27 via a barrier signal metal layer, and plugs comprising metal are formed in the via holes 26 via the barrier metal layer, in the same manner as described with reference to FIGS. 4G and 4H .
- the intermediate film 41 may also be formed with a silicon nitride oxide film or a silicon nitride film. Alternatively, it may be formed with an organic film that becomes an etching mask with respect to the first film having a low dielectric constant 13 and becomes an etching stopper with respect to the second film having a low dielectric constant 14 .
- the xerogel film, the fluorine resin film and the other organic films are being employed in the wiring structure for the object of suppressing the wiring capacitance increasing with the scale down.
- the organic film may be employed as a material having a specific inductive capacitance of 3 or less
- the fluorine resin may be employed as an organic film material having a specific inductive capacitance of 2.5 or less
- the xerogel film which is a gel having a network structure containing no water, may be employed as a material having a specific inductive capacitance of 2.5 or less.
- a film that can be used in a semiconductor device includes a silica series gel.
- a silica series gel for example, Nanoporous Silica produced by Nanoglass LLC can be used.
- the xerogel film of this type is inferior in mechanical strength, heat conductivity, heat resistance, water resistance and adhesiveness in comparison to the conventional inter level dielectric.
- the heat conductivity is remarkably poor as is from 1/10 to 1/100 of the organic film.
- fluorine resin commercial products, such as a film formed by plasma CVD (reported by NEC Corp. in IEDM (International Electron Devices Meeting) on 1997), Teflon (produced by Du Pont Corp.) and fluorinated polyimide (produced by Du Pont Corp.) have been developed.
- plasma CVD reactive chemical vapor deposition
- Teflon produced by Du Pont Corp.
- fluorinated polyimide produced by Du Pont Corp.
- these films are inferior in mechanical strength, heat conductivity, heat resistance and adhesiveness in comparison to the organic polymer having a specific inductive capacity of 2.5 or more.
- the invention employs a combination of a xerogel film and an organic film having a better film property than the xerogel film, or a combination of a fluorine resin film and an organic film having a better film property than the fluorine resin film, as described in the embodiments above, so as to realize to form a highly reliable wiring structure.
- the xerogel film or the fluorine resin film is used only in the part between the wirings, at which the wiring capacitance is increased by the scale down, and the other parts are formed with the organic film or the inorganic film having a low dielectric constant.
- the xerogel film or the fluorine resin film is applied to the part where the wiring interval is 0.3 ⁇ m or less because the wiring capacity is remarkably increased at the part where the wiring interval is 0.3 ⁇ m or less. According to this, an effect of decreasing the wiring capacitance can be obtained.
- FIGS. 7A to 7 I A fourth embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 7A to 7 I.
- a substrate 60 is constituted, for example, by forming a semiconductor element, such as a transistor, on a semiconductor substrate, and then forming wiring and dielectrics.
- a passivation film 61 is formed with a material, by which the wiring material is not diffused, such as a silicon nitride film, having a thickness of about 50 nm on the uppermost layer of the substrate 60 .
- a first inter level dielectric 62 in which a via hole is formed, is formed with a silicon oxide series material, such as a silicon oxide (SiO 2 ) film (an inorganic film) having a thickness of 500 nm, and then a second inter level dielectric 63 , in which wiring is formed, is formed with an organic material, such as a polyaryl ether film having a thickness of 500 nm.
- a first film 64 for forming a first mask is formed with a silicon oxide film having a thickness of 100 nm, and then a second film 65 for forming a second mask is formed with a silicon nitride film having a thickness of 100 nm.
- a resist mask 81 for forming a wiring groove is formed on the second film 65 by conducting an ordinary resist coating process and an ordinary lithography process.
- an opening 82 for forming the wiring groove is formed in the resist mask 81 .
- the first film 65 is etched by using the resist mask 81 (see FIG. 7B ) to open a wiring groove pattern 66 for forming the wiring groove, so as to form a second mask 67 .
- an ordinary parallel flat palate type plasma etching apparatus is used, and trifluoromethane (CHF 3 ), argon (Ar) and oxygen (O 2 ) are used as an etching gas.
- the substrate temperature is 0° C.
- the resist mask 81 is removed.
- a resist mask 83 used for forming a via hole is formed on the second mask 67 and the wiring groove pattern 66 by again conducting an ordinary resist coating process and an ordinary lithography process.
- an opening 84 for forming the via hole is formed in such a manner that it at least overlaps the wiring groove pattern 66 .
- the first film 64 is etched by using the resist mask 83 as an etching mask to form a via hole pattern 68 for forming the via hole, so as to form a first mask 69 .
- an ordinary parallel flat palate type plasma etching apparatus is used, and octafluorobutane (C 4 F 8 ), argon (Ar) and oxygen (O 2 ) are used as an etching gas.
- the substrate temperature is 0° C.
- the second inter level dielectric 63 is etched by using the first mask 69 as an etching mask to extend the via hole pattern 68 .
- the resist mask 83 is simultaneously etched and removed.
- an ordinary high-density plasma etching apparatus, and ammonia (NH 3 ) is used as an etching gas.
- the substrate temperature is ⁇ 20° C.
- the wiring groove pattern 66 is extended to the first mask 69 by using the second mask 67 as an etching mask.
- the first inter level dielectric 62 is etched by using the second inter level dielectric 63 as an etching mask to form a via hole 70 .
- an ordinary parallel flat palate type plasma etching apparatus is used, and octafluorobutane (C 4 F 8 ), argon (Ar) and oxygen (O 2 ) are used as an etching gas.
- the substrate temperature is set at 0° C.
- the second inter level dielectric 63 is etched by using the first mask 69 as an etching mask to form a wiring groove 71 .
- an ordinary high-density plasma etching apparatus, and ammonia (NH 3 ) is used as an etching gas.
- the substrate temperature is ⁇ 100° C.
- the passivation film 61 exposed at the bottom of the via hole 70 is etched.
- the second mask 67 (see FIG. 7H ) comprising the same material as the passivation film is also etched and removed.
- an ordinary high-density plasma etching apparatus is used, and sulfur hexafluoride (SF 6 ) is used as an etching gas.
- the substrate temperature is 0° C.
- the wiring groove 71 is formed in the second inter level dielectric 63
- the via hole 70 is formed in the first inter level dielectric 62 and the passivation film 61 as being connected to the bottom of the wiring groove 71 .
- silicon oxide (SiO 2 ) film is used as the first inter level dielectric 62 in this embodiment, silicon oxide fluoride (SiOF), for example, may also be used.
- the second mask layer 65 is formed with a silicon nitride film, it may be formed with a high melting point metal film or a high melting point metal compound film, such as a titanium nitride film. That is, any material may be used as far as the material has etching selectivity to the silicon oxide series material. It is preferred to use a film having light transmissibility, by which optical alignment can be conducted.
- the fourth embodiment of the process for producing a semiconductor device comprises a step of forming, on the second inter level dielectric 63 , the first mask 69 to be an etching mask for etching the first and second inter level dielectrics 62 and 63 , and a step of forming, on the first mask 69 , the second mask 67 , which comprises a material different from the first mask 69 , to be an etching mask for etching the second inter level dielectric 63 .
- first and second inter level dielectrics 62 and 63 are etched by using the first mask 69 as an etching mask to form the via hole 70 , and then the second inter level dielectric 63 is etched by using the second mask 67 having the wiring groove pattern 66 , which is different from the first mask 69 , as an etching mask to form the wiring groove 71 .
- the second inter level dielectric 63 which becomes an inter level dielectric between wiring in the same wiring layer, is formed with a polyaryl ether film, which is an organic polymer film, the dielectric constant between the wirings is decreased in comparison to the case where the second inter level dielectric 63 is formed with a silicon oxide series material, and thus the wiring capacitance is also decreased in comparison to the case where the second inter level dielectric 63 is formed with a silicon oxide series material.
- the resist process (a step of patterning a resist film) used for forming the first and second masks 69 and 67 can be conducted under the condition in that the second inter level dielectric 63 is not exposed. That is, the first film 64 is formed as an underlayer layer in the resist process for forming the second mask 67 , and the first film 64 covers the second inter level dielectric 63 in the resist process for forming the first mask 69 . Therefore, the restoration treatment of the resist can be conducted without exposing the second inter level dielectric 63 , i.e., an organic film, in which the resist films 81 and 83 formed in the resist processes can be removed, and the resist films 81 and 83 are again formed and patterned.
- the second inter level dielectric 63 i.e., an organic film
- the resist film 83 to be an etching mask for forming the first mask 69 can be removed simultaneously with the etching of the second inter level dielectric 63 , the operation of removing the resist film 83 is not necessary. Therefore, the process can be simplified.
- a via hole pattern (not shown in the figure) to be a pattern for forming the via hole also in the second mask 67 can be formed.
- FIGS. 8A to 8 F a plan view for the arrangement is shown in the upper part, and a cross sectional view is shown in the lower part.
- an opening 84 formed in a resist film 83 for forming a via hole pattern is formed deviating from a wiring groove pattern 66 formed in a second mask 67 .
- the second mask 67 is etched, and further a first film 64 is etched, to form a via hole pattern 68 , so as to form a first mask 69 , as shown in FIG. 8 B.
- the wiring groove pattern 66 and the via hole pattern 68 are formed in the second mask 67 .
- the second inter level dielectric 63 is then etched by using the first mask 69 as an etching mask to form the via hole pattern 68 . Therefore, the via hole pattern 68 having the opening area that conforms to its design can be formed. In this etching step, the resist mask 83 (see FIG. 8B ) is simultaneously etched and removed.
- the wiring groove pattern 66 is extended to the first mask 69 by using the second mask 67 as an etching mask.
- the first inter level dielectric 62 is etched by using the second inter level dielectric 63 as an etching mask to form a via hole 70 .
- the via hole pattern 68 formed in the second inter level dielectric 63 is formed to have the opening area that conforms to its design
- the via hole 70 is formed to have the opening area that conforms to its design.
- the second inter level dielectric 63 is then etched by using the first mask 69 as an etching mask to form a wiring groove 71 .
- the passivation film 61 exposed at the bottom of the via hole 70 is etched.
- the second mask 67 (see FIG. 8E ) comprising the same material as the passivation film is also etched and removed.
- the wiring groove 71 is formed in the second inter level dielectric 63
- the via hole 70 is formed in the first inter level dielectric 62 and the passivation film 61 as being connected to the bottom of the wiring groove 71 .
- the via hole pattern 68 having an opening area that conforms to its design is formed in the second inter level dielectric 63 , and the via hole 70 is not filled with the inter level dielectric after forming the via hole 70 . Therefore, the via hole 70 having a narrowed opening area as in the case of FIGS. 2A to 2 F is not formed.
- the opening area of the via hole can be ensured even when the via hole pattern deviates from the wiring groove pattern due to misalignment occurring on forming the via hole pattern.
- the effect of ensuring the opening area of the via hole can be obtained in any case where the wiring groove pattern and the via hole pattern relatively deviate from each other.
- the first film 65 to be the first mask 69 is formed with a material having light transmissibility, such as a silicon oxide film used herein
- the second film 65 to be the second mask is formed with a material having light transmissibility, such as a silicon nitride film used herein. Therefore, in the exposure step hereafter, the mask alignment to align the position of the mask to the underlayer can be conducted by alignment using light or alignment using an image processing. It has been known that a silicon oxide film and a silicon nitride film transmit light in the wavelength region of from 200 to 1,000 nm used for alignment.
- an etching stopper layer having a high dielectric constant (for example, a silicon nitride film, a silicon oxide film or a silicon oxide nitride film), which has been conventionally used, is not necessary by utilizing the difference in characteristics of the materials between the first inter level dielectric 62 and the second inter level dielectric 63 .
- the wiring grooves 71 can be formed in the second inter level dielectric 63 to be a wiring layer with good controllability.
- the wiring groove pattern 66 is extended to the first mask 69 comprising a silicon oxide film, and at the same time, the first inter level dielectric 62 comprising a silicon oxide film is etched as described in the foregoing.
- the process comprises the step of forming, on the inter level dielectric, the first mask to be an etching mask for etching the inter level dielectric, and a step of forming, on the first mask, the second mask to be an etching mask for etching the inter level dielectric, the second mask comprising a material different from the first mask. Therefore, the inter level dielectric is etched by using the first mask as an etching mask to form the via holes, and then the inter level dielectric is etched by using the second mask as an etching mask to a pattern different from the first mask, to form the wiring grooves.
- the wiring capacitance can be reduced.
- an organic film or an inorganic film is used only in the inter level dielectric between the wirings layer among the inter level dielectrics, deterioration of the mechanical strength of the whole inter level dielectrics can be suppressed even when the inter level dielectric between the wirings is formed with a xerogel or a fluorine resin. Therefore, a semiconductor device combining copper wiring, a fluorine resin and an organic film, or a semiconductor device combining copper wiring, a xerogel and an organic film can be formed without deterioration of the yield.
- the resist process for forming the second mask the first film is formed on the underlayer, and in the resist process for forming the first mask, the first film covers the inter level dielectric. Therefore, the resist processes for forming the first and second masks can be conducted under the condition in that the inter level dielectric is not exposed, and thus the restoration treatment of the resist film can be conducted in the resist process.
- the pattern for forming the via hole can also be formed in the second mask. Therefore, the narrowing of the opening area of the via hole described in FIGS. 2A to 2 F does not occur.
- the mask alignment in the exposure step of the lithography process conducted after forming the film for forming the first mask and the film for forming the second mask can be conducted in the same alignment method as the conventional process.
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Abstract
A process for producing a semiconductor device for forming a highly reliable wiring structure is provided that solves the problem occurring on using a xerogel or a fluorine resin in an inter level dielectric between the wirings to decrease a wiring capacitance, and the problem occurring on misalignment. A process for producing a semiconductor device comprising an inter level dielectric containing a xerogel film or a fluorine resin film comprises a step of forming, on the inter level dielectric comprising a lower layer of the inter level dielectric formed with an organic film and an upper layer of the inter level dielectric formed with a xerogel film or a fluorine resin film, a first mask to be an etching mask for forming a via contact hole by etching the inter level dielectric, and a step of forming, on the first mask, a second mask, which comprises a different material from the first mask, to be an etching mask for forming a wiring groove by etching the inter level dielectric.
Description
1. Field of the Invention
The present invention relates to a process for producing a semiconductor device, and more particularly, it relates to a process for producing a semiconductor device having a multi-layer wiring structure used for device process beyond the design rule of 0.25 μm.
2. Description of the Related Art
With the scale down of a semiconductor device, scale down of wiring and reduction of a wiring interval become necessary. Simultaneously, with the demand of low consuming electric power and high-speed operation, an inter level dielectric having a low dielectric constant and wiring having a low resistance become necessary. Particularly, in a logic device, because increase of the resistance and increase of the wiring capacitance due to the fine wiring bring about deterioration in operation speed, fine multi-layer wiring using a film having a low dielectric constant as an inter level dielectric becomes necessary.
In order to apply the dual damascene method to the inter level dielectric having a low dielectric constant, in which a conductive material is filled in a via hole and a wiring groove formed in the inter level dielectric, followed by flattening, it is necessary to employ a technique in which the via hole and the wiring groove can be simultaneously formed in the inter level dielectric having a low dielectric constant.
An organic polymer is receiving attention as the material for the inter level dielectric having a low dielectric constant. An organic polymer has a dielectric constant of about 2.7, which is lower than the conventional inter level dielectric using silicon oxide (SiO2) having a dielectric constant of about 4.0 and silicon oxide fluoride (SiOF) having a dielectric constant of about 3.5. Therefore, a great improvement in performance is expected in a semiconductor device using an organic polymer in an inter level dielectric. However, as the organic polymer is an expensive material, taking the balance between increase in cost and improvement in performance of the semiconductor device into consideration, it has been studied a structure, in which only the inter level dielectric having groove wiring formed therein is formed with the organic polymer, and the inter level dielectric having a via hole formed therein is formed with silicon oxide or silicon oxide fluoride, which has been conventionally used. An example of such a structure will be described below with reference to FIGS. 1A to 1F.
As shown in FIG. 1A , a passivation film 111 comprising a material, into which a wiring material is not diffused, is formed with a silicon nitride film on a substrate 110, in which transistors and wiring have been formed, and then a first inter level dielectric 112, in which a via hole is to be formed, is formed with a silicon oxide film having a thickness of 500 nm. A resist mask (not shown in the figure) for forming a via hole is formed on the first inter level dielectric 112, and a via hole 113 is formed in the first inter level dielectric 112 by etching using the resist mask as an etching mask. The resist mask is then removed.
As shown in FIG. 1B , a second inter level dielectric 114, by which the via hole 113 is filled, is formed with an organic polymer having a thickness of 500 nm on the first inter level dielectric 112.
As shown in FIG. 1C , a mask layer 115 to be an etching mask for forming a wiring groove is formed with a silicon oxide film having a thickness of 100 nm on the second inter level dielectric 114. A resist mask 116 for forming a wiring groove pattern is formed on the mask layer 115. An opening 117 for forming the wiring groove pattern is formed in the resist mask 116.
As shown in FIG. 1D , the wiring groove pattern 118 is formed in the mask layer 115 by etching using the resist mask 116 as an etching mask.
As shown in FIG. 1E , the second inter level dielectric 114 is etched by using the resist mask 116 (see FIG. 1D ) and the mask layer 115 as an etching mask to form a wiring groove 119, and the second inter level dielectric 114 filled in the via hole 113 is selectively removed to re-open the via hole 113 in the first inter level dielectric 112. Upon etching in this case, since the second inter level dielectric 114 comprising the organic polymer is etched, the resist mask 116 is simultaneously etched and removed. Therefore, a step of removing the resist mask 116 is not necessary.
Thereafter, as shown in FIG. 1F , the passivation film 111 exposed at the bottom of the via hole 113 is etched by using the first and second inter level dielectrics 112 and 114 as a mask. As a result, the wiring groove 119 and the via hole 113 having a dual damascene structure are formed.
The scale down of the wiring width and reduction of the interval bring about not only the aspect ratio of the wiring itself, but also the aspect ratio of the space among the wiring, and as a result, and thus difficulties are caused in the techniques for forming narrow and long wiring and the technique for filling a gap among fine wiring with an inter level dielectric. Thus, the process becomes complicated, and simultaneously the number of steps contained in the process is increased.
In a damascene process, in which after a via hole and a wiring groove are simultaneously filled with an aluminum series metal or a copper series metal by reflow sputtering, an excess metal on the inter level dielectric, in which the via hole and the wiring groove are formed, is removed by chemical mechanical polishing (hereinafter referred to as CMP), it is not necessary to form metallic wiring having a high aspect ratio by etching or to fill the gap among the wiring with an inter level dielectric, and thus the number of steps of the process can be greatly reduced. This process contributes to the reduction of the total cost in a greater extent when the aspect ratio of the wiring becomes larger, or the total number of the wiring becomes larger.
An inter layer dielectric having a low dielectric constant is applied to a device of a 0.18 μm or lower design role rule since it reduces the capacitance among the wiring. A film having a specific inductive capacity of 2.5 or less has a film property that is greatly different from a silicon oxide film used in the conventional device, and thus a process technique that can be applied to the film having a low dielectric constant is demanded.
Many of the films having a low dielectric constant of 3.0 or lower are organic films containing carbon, and they are employed instead of the conventional inter level dielectric. Oxygen is necessarily used on opening a via hole in the organic film used as the inter level dielectric. However since a resist comprising an organic film is used in the patterning technique used in the conventional process for producing a semiconductor device, there is a problem in that the film having a low dielectric constant is damaged in the step of removing the resist. Because the composition of the film having a low dielectric constant is similar to the composition of the resist, there is a possibility that the film having a low dielectric constant is removed in the step of removing the resist.
In recent years, an application of xerogel to a semiconductor device is receiving attention as a material expected to have a specific inductive capacity of 2.0 or less. The xerogel is a well-known material, for example, as silica gel used as a desiccating agent. The application of xerogel to a semiconductor device is difficult at present due to a demand of various kinds of reliability. That is, xerogel contains from 50 to 90% of pores by volume and thus has a problem in mechanical strength.
In the process described with reference to FIGS. 1A to 1F, the second inter level dielectric is filled in the via hole in the step shown in FIG. 1B. Therefore, in the step shown in FIG. 1E , because the second inter level dielectric in the via hole is etched until it is completely removed, over etching is often applied to the bottom of the wiring groove and the mask layer. As a result, the shoulder parts of the bottom of the wiring groove and the mask layer are cut by a sputtering phenomenon, and a wiring groove and a via hole having a good shape are difficult to be obtained. In the case where the interval of the wiring grooves is narrow, the wiring grooves adjacent to each other are connected due to the cutting of the shoulder parts of the mask layer, so as to cause a defect such as a short circuit.
In the process technique shown in FIGS. 1A to 1F, when the wiring groove is formed beyond. the via hole due to misalignment, the contact area of the via hole becomes small to cause problems, such as increase of the contact resistance, defective filling of the metal in the via hole, and deterioration of resistance to electro-migration. The misalignment will be described in detail below with reference to FIGS. 2A to 2F.
As similar to the case shown in FIGS. 1A and 1B , after forming a passivation film 111 on a substrate 110, a first inter level dielectric 112 is formed, and then a via hole 113 is formed in the first inter level dielectric 112, as shown in FIG. 2A. As shown in FIG. 2B , a second inter level dielectric 114 filling the via hole 113 is formed on the first inter level dielectric 112.
As shown in FIG. 2C , after forming a mask layer 115 on the second inter level dielectric 114, a resist mask 116 for forming a wiring groove pattern is formed on the mask layer 115. An opening 117 for forming the wiring groove pattern is formed in the resist mask 116. At this time, it is assumed that the opening 117 is formed deviating from the via hole 113 due to misalignment.
As shown in FIG. 2D , a wiring groove pattern 118 is formed in the mask layer 115 by etching using the resist mask 116 as an etching mask.
As shown in FIG. 2E , the second inter level dielectric 114 is etched by using the resist mask 116 (see FIG. 2D ) and the mask layer 115 as an etching mask to form a wiring groove 119, and the second inter level dielectric 114 filled in the via hole 113 is selectively removed to re-open the via hole 113 in the first inter level dielectric 112. At this time, because the wiring groove 119 is formed deviating from the via hole 113 due to the misalignment, the second inter level dielectric 114 remains in a part of the via hole 113 to stuff up a part of the via hole 113, and thus the opening area is decreased.
As shown in FIG. 2F , the passivation film 111 exposed at the bottom of the via hole 113 is etched by using the first and second inter level dielectrics 112 and 114 as a mask. When the wiring groove 119 and the via hole 113 having a dual damascene structure are formed as described in the foregoing, because a part of the via hole 113 is stuffed up by the second inter level dielectric 114, the contact area becomes small to cause increase in contact resistance.
An object of the invention is to provide a process for producing a semiconductor device for solving the problems described in the foregoing.
The invention relates to a process for producing a semiconductor device comprising an inter level dielectric comprising a xerogel film or an organic film, the process comprising a step of forming, on an inter level dielectric, a first mask to be an etching mask for etching the inter level dielectric; and a step of forming, on the first mask, a second mask comprising a different material from the first mask to be an etching mask for etching the inter level dielectric.
Because the process for producing a semiconductor device of the invention comprises the step of forming, on an inter level dielectric, a first mask to be an etching mask for etching the inter level dielectric; and the step of forming, on the first mask, a second mask comprising a different material from the first mask to be an etching mask for etching the inter level dielectric, after the inter level dielectric is etched by using the first mask as an etching mask, the inter level dielectric can be etched by using the second mask as an etching mask to a pattern different from the first mask.
In the process for producing a semiconductor device, a lower layer of the inter level dielectric formed between wiring layers may be formed with an organic film, and an upper layer of the inter level dielectric formed between wiring of the same wiring layer may be formed with a xerogel film or an organic film.
In this embodiment of the production process, since the upper layer of the inter level dielectric formed between wiring of the same wiring layer is formed with a xerogel film or an organic film, such as a fluorine resin film, the dielectric constant between wiring of the same wiring layer, which becomes the maximum wiring capacitance, can be about from 1.8 to 2.4, and thus the wiring capacitance can be reduced.
Specifically, in a semiconductor device having the minimum interval of wiring, in particular, one of a design rule of 0.18 μm or less, a xerogel film or an organic film, such as a fluorine resin film, is applied to the part where the wiring interval is 0.3 μm or less. While the wiring capacitance is generally remarkably increased at the part where the wiring interval is 0.3 μm or less, an effect of decreasing the wiring capacitance can be obtained by using the xerogel film or the organic film, such as a fluorine resin film.
On the other hand, there is no large influence relating to the increase in capacitance at the part where the wiring interval is larger than 0.3 μm (for example, one between wiring layers vertically stacked). Therefore, it is sufficient to use an organic film having a specific inductive capacity of 3 or less at the part where the wiring interval exceeds 0.3 μm. A fluorine resin film may also be used as the organic film. As described in the foregoing, scale down of the wiring interval can be realized in the invention. Furthermore, by using a xerogel film or an organic film, such as a fluorine resin film, only between the wirings, and by using an organic film having a low dielectric constant of 3 or less for the other parts, the remarkable deterioration of the mechanical strength of the whole inter level dielectrics can be suppressed. In the case where the upper layer of the inter level dielectric is formed with an organic film, the lower layer of the inter level dielectric can be formed with an organic film, and the same function described in the foregoing can also be obtained in this case.
In the process for producing a semiconductor device of the invention, a pattern for forming the wiring groove may be formed in the second mask, and a pattern for forming the via hole is formed in the first mask in such a manner that the pattern for forming the via hole at least overlaps the pattern for forming the wiring groove. That is, the process for producing a semiconductor device may comprise, a step of forming, on the inter level dielectric, a first film for forming the first mask; a step of forming, on the first film, a second film for forming the second mask; a step of forming the second mask by forming a pattern or forming the wiring groove in the second film; and a step of forming the first mask by forming a pattern for forming the via hole in the first film is such a manner that the pattern for forming the via hole at least overlaps the pattern for forming the wiring groove.
In this embodiment of the production process, the resist process used for forming the first and second masks can be conducted under the condition in that the inter level dielectric is not exposed. That is, in the resist process for forming the second mask, the first film is formed as an underlayer, and in the resist process for forming the first mask, the first film itself covers the inter level dielectric. Thus, the restoration treatment of the resist process can be conducted.
Even when misalignment occurs on forming the pattern of the first mask for forming the via hole, the pattern for forming the via hole can also be formed in the second mask, and there is no possibility that the opening area of the via hole is reduced as described with reference to FIGS. 2A to 2F.
Furthermore, because the first mask and the second mask are formed with a material having light transmissibility, the so-called mask alignment, where the position of the mask is aligned to the underlayer upon exposure, can be conducted by an alignment method using light or an alignment method using an image processing.
A first embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 3A to 3F, 4G and 4H.
As shown in FIG. 3A , an underlying substrate 11 comprises, for example, a substrate 51 having thereon transistors (not shown in the figure), and an inter metal dielectric 52 covering thereon, in which wiring 53 is formed. A first film having a low dielectric constant 13 to be a lower layer of an inter level dielectric 12 is formed on the underlying substrate 11 to a thickness of, for example, from 300 to 800 nm. The first film having a low dielectric constant 13 becomes an inter level dielectric (ILD) between wiring layers, and can be formed with an organic film having a specific inductive capacity of about 2.5. In this embodiment, an organic polymer totally called as polyaryl ether is employed. Specific examples of the polyaryl ether include flare (a tradename, produced by Aliedsignal Inc.), SILK (a trade name, produced by Dow Chemical Corp.) and VELOX (a trade name, produced by Schumacher Corp.). Alternatively, a BCB (bis-benzocyclobutene) film, a polyimide film and an amorphous carbon film may be used.
The formation of the organic polymer can be conducted, for example, by a precursor is coated as a film on the underlying substrate 11 by spin coating, and then cured at a temperature of from 300 to 450° C. In the case where the surface of the underlying substrate 11 is hydrophobic, and the adhesion to the organic film is poor, or in the case where diffusion of copper is prevented, while not shown in the figure, a silicon oxide film, a silicon oxide nitride film, a silicon carbide film or a titanium nitride silicate film is formed.
The silicon oxide film can be formed, for example, by the following manner. A commercially available SOG (spin on glass, for example, an SOG mainly comprising silanol, and an SOG mainly comprising a polymer containing silanol) is coated to a thickness of from 30 to 100 nm by a spin coating method. The coated film is baked at a temperature of from 150 to 200° C. for about 1 minute, and then cured at a temperature of from 350 to 450° C. for about from 30 to 60 minutes.
The silicon oxide film may be formed by a plasma CVD (chemical vapor deposition) method using a commercially available plasma CVD apparatus. In the case where the wiring 53 is copper wiring, it is not preferred to form the silicon oxide film by a normal plasma CVD method because the copper wiring is oxidized. However, the copper wiring can be prevented from oxidation as possible by using dinitrogen monoxide (N2O) gas as the oxidizing agent, using a silane series gas (for example, monosilane (SiH4), disilane (Si2H6) or trisilane (Si3H8)) as the silicon source, setting the substrate temperature to 300 to 400° C., setting the plasma power to 350 W, and the pressure of the film forming environment to about 1 kPa.
In the case of the silicon nitride oxide film, a commercially available inorganic SOG containing an amino group may be, for example, by formed into a film by a spin coating method. It is preferred that the film formation is conducted by the plasma CVD method. Examples of the gas used in the plasma CVD method include a silane series gas (monosilane (SiH4), disilane (Si2H6) or trisilane (Si3H8)) as the silicon source, ammonia and hydrazine as the nitriding agent, and dinitrogen monoxide (N2O) as the oxidizing agent. As the carrier gas, an inert gas, such as nitrogen, helium and argon, is employed. The film formation is conducted, for example, under such conditions that the substrate temperature is from 300 to 400° C., the plasma power is 350 W, and the pressure of the film forming environment is about 1 kPa.
In the case of the silicon nitride film, it can be formed by spin coating of a commercially available inorganic SOG containing an amino group as similar to the case of the silicon nitride oxide film. It is preferred that the film formation is conducted by the plasma CVD method. Examples of the gas used in the plasma CVD method include a silane series gas (monosilane (SiH4)), disilane (Si2H6) or trisilane (Si3H8)) as the silicon source, ammonia and hydrazine as the nitriding agent, and dinitrogen monoxide (N2O) as the oxidizing agent. As the carrier gas, an inert gas, such as nitrogen, helium and argon, is employed. The film formation is conducted, for example, under such conditions that the substrate temperature is from 300 to 400° C., the plasma power is 350 W, and the pressure of the film forming environment is about 1 kPa.
The silicon carbide film can be formed, for example, by using a parallel flat palate type plasma CVD apparatus. Examples of the gas used in the plasma CVD method include methyl silane as the silicon source. The film formation is conducted, for example, under such conditions that the substrate temperature is from 300 to 400° C., the plasma power is from 150 to 350 W, and the pressure of the film forming environment is about from 100 Pa to 1 kPa.
A second film having a low dielectric constant 14 to be an upper layer of the inter level dielectric 12 is formed to a thickness, for example, of 400 nm on the first film having a low dielectric constant 13. The second film having a low dielectric constant 14 is formed with a fluorine resin. Examples of the film include a fluorocarbon film, such as a cyclic fluorine resin, polytetrafluoroethylene (PTFE), amorphous PTFE (for example, Teflon AF, a trade name, produced by Du Pont Corp.), fluorinated aryl ether and fluorinated polyimide. Alternatively, a xerogel (for example, porous silica) may be employed.
The film of the fluorine resin can be formed by the manner, in which a precursor of the fluorine resin is coated on the first film having a low dielectric constant 13 by a spin coating apparatus, and then cured at a temperature of from 300 to 450° C. The materials, such as fluorinated amorphous carbon, can be formed by a plasma CVD method using acetylene (C2H2) and a fluorocarbon gas (for example, octafluorobutane (C4F8)) as the process gas. In this case, the film thus formed is cured at a temperature of from 300 to 450° C. The amorphous PTFE is not limited to Teflon AF and may be any substance having the structure represented by the following formula (1):
wherein m and n each represent a positive integer.
wherein m and n each represent a positive integer.
As the second film having a low dielectric constant 14, a cyclopolymerized fluorinated polymer series resin (for example, Cytop, a trade name) may be used. The cyclopolymerized fluorinated polymer series resin is not limited to Cytop and may be any substance having the structure represented by the following formula (2):
wherein x, y and z each represent a positive integer.
wherein x, y and z each represent a positive integer.
As the second film having a low dielectric constant 14, a fluorinated polyaryl ether series resin (for example, FLARE, a trade name) may be used. The fluorinated polyaryl ether series resin is not limited to FLARE and may be any substance having the structure represented by the following formula (3);
wherein R represents an alkyl group.
wherein R represents an alkyl group.
In the case where a xerogel is used as the second film having a low dielectric constant 14, Nanoporous Silica developed by Nanoglass LLC is formed into a film by using a spin coating apparatus developed by Nanoglass LLC. Nanoporous Silica is a kind of porous silica, and the xerogel that can be used in the invention is not limited to Nanoporous Silica. That is, any type of xerogels that can be formed by the following method can be used. A silanol resin having an alkyl group having a relatively high molecular weight, such as an aromatic group, is coated on a substrate and gelled, and the film is then subjected to a hydrophobic treatment by using a silane coupling agent or a hydrogenating treatment.
According to the manner described in the foregoing, the inter level dielectric 12 comprising the first film having a low dielectric constant 13 and the second film having a low dielectric constant 14 is formed on the underlying substrate
As shown in FIG. 3B , a first film 15 for forming a first mask as an inorganic mask is formed with a silicon oxide film having a thickness of from 50 to 300 nm on the inter level dielectric 12, i.e., on the second film having a low dielectric constant 14. A second film 16 for forming a second mask is formed with a silicon nitride film having a thickness of from 50 to 150 nm. In the film forming method of these films, an ordinary CVD apparatus is used under the same conditions as described in the foregoing.
Before forming the silicon oxide film, it is preferred that a film having a larger silicon content than the silicon nitride film, the amorphous silicon nitride film, the silicon oxide film or the stoichiometric amount is formed, depending on necessity, particularly in the case where the oxidation of the second film having a low dielectric constant 15 causes a problem. That is, a CVD film is formed under a reductive atmosphere. The film thickness is preferably as thin as possible, and is generally about 10 nm. As described herein, the first film 15 is formed with a silicon oxide film that is excellent in light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment, and the second film 16 is also formed with a silicon nitride film having light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment.
As the inorganic mask, a metallic film or a metallic compound film, such as titanium, titanium nitride, tantalum and tantalum nitride, can be used, as well as the silicon nitride film. The film thickness thereof is preferably from 50 to 150 nm. The film formation thereof can be conducted by sputtering, which is generally employed in film formation of a metallic film and a metallic compound film.
As shown in FIG. 3C , a resist film 17 is formed on the second film 16 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 17 is patterned by a lithography technique to form openings 18 for forming wiring grooves.
Subsequently, only the second film 16 is etched by using the resist film 17 as an etching mask to form openings 19 for forming wiring grooves, so as to form a second mask 21 to be an etching mask for forming wiring grooves in the inter level dielectric 12. In this step, only the second film 16 is selectively etched by using an ordinary magnetron type etching apparatus. As the etching conditions where the second film 16 comprises a silicon nitride film, for example, trifluoromethane (CHF3) (5 cm3/min), oxygen (O2) (5 cm3/min) and argon (Ar) (20 cm3/min) are used as the etching gas, and an RF plasma is set at 600 W. In the case where the second film 16 comprises a metallic compound film, a chlorine series etching gas, such as boron chloride (BCl) and chlorine (Cl2), is used as the etching gas. Thereafter, the resist film 17 is removed by ashing. FIG. 3C shows the state before removing the resist film 17.
As shown in FIG. 3D , a resist film 22 is formed on the second film 16 and the first film 15 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 22 is patterned by a lithography technique to form openings 23 for forming via holes at positions within the openings 19 for forming the wiring grooves from the plan view of the second film 16.
Subsequently, only the first film 15 is etched by using the resist film 22 as an etching mask to form openings 24 for forming via holes in the inter level dielectric 12, so as to form a first mask 25 to be a etching mask for forming the via holes in the inter level dielectric 12.
The second film having a low dielectric constant 14 of the inter level dielectric 12 is etched by using an ordinary etching apparatus using the resist film 22 as an etching mask. As the etching conditions, for example, hexafluoroethane (C2F6) (14 cm3/min), carbon monoxide (180 cm3/min) and argon (240 cm3/min) are used as an etching gas, and an RF plasma is set at 1.5 kw. Because the first film having a low dielectric constant 13 comprising an organic film is present as an underlayer of the second film having a low dielectric constant 14, the etching is stopped at the upper surface of the first film having a low dielectric constant 13.
As shown in FIG. 3E , the first film having a low dielectric constant 13 is etched by using an ordinary etching apparatus using the first mask 25 as an etching mask, to form via holes 26 in the inter level dielectric 12. As an etching gas in the etching, nitrogen is used, and ammonia and a hydrogen gas are also used depending on necessity. At the time where the first film having a low dielectric constant 13 comprising an organic film is etched, the resist film 22 (see FIG. 3D ) is also etched and completely removed. Therefore, there is no necessity to conduct resist ashing in this stage.
As shown in FIG. 3F , by using the second mask 21 comprising a silicon nitride film (or a metallic compound film), the first mask 25 is etched, and then the second film having a low dielectric constant 14 is etched, so as to form wiring grooves 27 in the second film having a low dielectric constant 14. The etching conditions of this step are the same as those for etching the second film having a low dielectric constant 14 described in the foregoing.
As shown in FIG. 4G , wiring is formed by a damascene method. A barrier metal layer 31 comprising tantalum nitride is formed on the inner walls of the wiring grooves 27 and the via holes 26 by sputtering or by a CVD method. At this time, the barrier metal layer 31 is also formed on the second mask 21. A wiring material (metal), such as copper, is accumulated by sputtering, a CVD method or an electrolytic plating method. In the case where the metal 32 is accumulated by an electrolytic plating method, a seed layer (not shown in the figure) comprising the same metal as the metal 32 to be accumulated is formed in advance.
Thereafter, an excess metal 32 and the barrier metal layer 31 on the second mask 21 are removed by polishing using CMP, and, as shown in FIG. 4H , wiring 33 comprising the metal 32 is formed on the wiring grooves 27 via the barrier metal layer 31, so as to form plugs 34 comprising the metal 32 in the via holes 26 via the barrier metal layer 31. In this step, the second mask 21 functions as a polishing stopper, but in some cases, the second mask 21 may be completely removed depending on the thickness of the second mask 21. In this CMP, for example, an alumina slurry is employed.
While not shown in the figure, the process comprising from the step of forming the inter level dielectric 12 to the step of forming the wiring 33 and the plugs 34 may be repeated to form a multi-layer wiring. The inter metal dielectric 52 among the wiring 53 may be formed with a xerogel film or a fluorine resin film by the similar process as the foregoing.
In the descriptions in the foregoing, while an example is described, in which the inter level dielectric 12 is formed on the underlying substrate 11 having semiconductor elements formed therein, the production process can be applied to the case where the inter level dielectric 12, the via holes 26, the wiring grooves 27, the wiring 33 and the plugs 34 having the constitution described above are formed on a substrate having no semiconductor element.
The process for producing a semiconductor device described in the foregoing comprises a step of forming, on the inter level dielectric 12, the first mask 25 to be an etching mask for etching the inter level dielectric 12, and a step of forming, on the first mask 25, the second mask 21 to bean etching mask for etching the inter level dielectric 12, the second mask 21 comprising a material different from the first mask 25. Therefore, the inter level dielectric 12 is etched by using the first mask 25 as an etching mask to form the via holes 26, and then the upper layer of the inter level dielectric 12, i.e., the second film having a low dielectric constant 14, is etched by using the second mask 21 as an etching mask to a pattern for forming wiring grooves different from the first mask 25, to form the wiring grooves 27.
Furthermore, because the upper layer of the inter metal dielectric between the wirings in the same wiring layer, i.e., the second film having a low dielectric constant 14, is formed with a xerogel film or a fluorine resin film, the dielectric constant between the wirings in the same wiring layer where the wiring capacity becomes maximum is about from 1.8 to 2.4, and thus the wiring capacitance is reduced. Specifically, in a semiconductor device having the minimum interval of wiring, in particular, one of a design rule of 0.18 μm or less, a xerogel film or a fluorine resin film is applied to the part where the wiring interval is 0.3 μm or less. While the wiring capacitance is generally remarkably increased at the part where the wiring interval is 0.3 μm or less, an effect of decreasing the wiring capacitance can be obtained by using the xerogel film or the fluorine resin film.
On the other hand, there is no large influence relating to the increase in capacitance at the part where the wiring interval is larger than 0.3 μm (for example, one between the wirings 53 and the wiring 33) Therefore, it is sufficient to use an organic film having a specific inductive capacity of 3 or less at the part where the wiring interval excess 0.3 μm. As described in the foregoing, scale down of the wiring interval can be realized in the invention. Furthermore, by using a xerogel film or a fluorine resin film only between the wirings, and by using an organic film having a low dielectric constant for the other parts, the remarkable deterioration of the mechanical strength of the whole inter level dielectrics can be suppressed.
Furthermore, the resist process (a step of patterning the resist film) for forming the first and second masks 25 and 21 can be conducted under the condition where the inter level dielectric 12 is not exposed. That is, in the resist process for forming the second mask 21, the first film 15 is formed as an underlayer, and in the resist process for forming the first mask 25, the first film 15 itself covers the inter level dielectric 12. Thus, without exposing the inter level dielectric 12 comprising an organic film, the resist films 17 and 22 formed by the resist process can be removed, and a restoration treatment of the resist where the resist films 17 and 22 are again formed and patterned can be conducted. Furthermore, because the resist film 22 to be an etching mask for forming the first mask can be removed simultaneously to the etching of the first film having a low dielectric constant 13, the operation of removing the resist film 22 by ashing is not necessary. Therefore, the process can be simplified.
In the resist process where the openings 24 to be a pattern for forming the via holes are formed in the first mask 25, i.e., in the process for forming the openings 23 in the resist film 22, even when misalignment occurs to form the openings 23 formed in the resist film 22 deviating from the openings 19 to be a pattern for forming the wiring grooves, because openings (not shown in the figure) to be a pattern for forming the via holes can be formed in the second mask 21, a via holes having a narrowed opening area is not formed as described with reference to FIGS. 2A to 2F.
Furthermore, when the first film 15 to be the first mask 25 is formed with a material having light transmissibility, for example, a silicon oxide film used herein, and the second film 16 to be the second mask is formed with a material having light transmissibility, for example, a silicon nitride film used herein, the mask alignment, where the position of the mask is aligned to the underlayer in an exposure step, can be conducted by an ordinary alignment method using light or an alignment method using an image processing. It has been known that a silicon oxide film and a silicon nitride film transmit light in the wavelength region of from 200 to 1,000 nm used for alignment.
Moreover, an etching stopper layer having a high dielectric constant (for example, a silicon nitride film, a silicon oxide film or a silicon oxide nitride film), which has been conveniently used, is not necessary by utilizing the difference in characteristics of the materials. For example, when the conditions for etching the second film having a low dielectric constant 14 (a xerogel film or a fluorine resin film) are selected in such a manner that the first film having a low dielectric constant 13 (an organic film) is not etched, the wiring grooves 27 can be formed in the second film having a low dielectric constant 14 to be a wiring layer with good controllability. When the etching for forming the via holes 26 is conducted, the second film having a low dielectric constant 14 comprising a xerogel or a fluorine resin is etched, and simultaneously the first film having a low dielectric constant 13 comprising an organic film is etched.
A second embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 5A to 5C. In FIGS. 5A to 5C, the same symbols are attached to the same constitutional components as in FIGS. 3A to 3F, 4G and 4H.
As shown in FIG. 5A , an underlying substrate 11 comprises, for example, a substrate 51 having thereon transistors (not shown in the figure), and an inter metal dielectric 52 covering thereon, in which wiring 53 is formed. A first film having a low dielectric constant 13 to be a lower layer of an inter level dielectric 12 on the underlying substrate 11 is formed, for example, with an inorganic film having a thickness of from 300 to 800 nm.
A second film having a low dielectric constant 14 to be an upper layer of the inter level dielectric 12 is formed to a thickness, for example, of 400 nm on the first film having a low dielectric constant 13. The second film having a low dielectric constant 14 is formed with a fluorine resin. As the fluorine resin, the materials described for the first embodiment can be employed.
The inter level dielectric 12 comprising the first film having a low dielectric constant 13 and the second film having a low dielectric constant 14 is thus formed on the underlying substrate 11.
A first film 15 for forming a first mask as an inorganic mask is formed with a silicon oxide film having a thickness of from 50 to 300 nm on the inter level dielectric 12, i.e., on the second film having a low dielectric constant 14. A second film 16 for forming a second mask is formed with a silicon nitride film having a thickness of from 50 to 150 nm. The film forming method of these films is the same as those described for the first embodiment.
According to the same manner as described with reference to FIG. 3C , only the second film 16 is etched to form openings 19 for forming wiring grooves, so as to form a second mask 21 to be an etching mask for forming the wiring grooves in the inter level dielectric 12.
A resist film 22 is formed on the second film 16 and the first film 15 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 22 is patterned by a lithography technique to form openings 23 for forming via holes at positions within the openings 19 for forming the wiring grooves from the plan view of the second film 16.
Subsequently, only the first film 15 is etched by using the resist film 22 as an etching mask to form openings 24 for forming via holes in the inter level dielectric 12, so as to form a first mask 25 to be an etching mask for forming the via holes in the inter level dielectric 12.
The second film having a low dielectric constant 14 of the inter level dielectric 12 is etched by using an ordinary etching apparatus using the first mask 25 as an etching mask. As the etching conditions, for example, nitrogen (N2) (48 cm3/min) and helium (He) (200 cm3/min) are used as an etching gas, a microwave power is set at 1.35 kW (2.45 GHz), an RF plasma is set at 150 W, and a substrate temperature is set at −50° C. Because the resist film 22 is etched and completely removed in this etching step, removal of the resist is not necessarily conducted. Furthermore, because the first film having a low dielectric constant 13 comprising an inorganic film is present as an underlayer of the second film having a low dielectric constant 14, the etching is stopped at the upper surface of the first film having a low dielectric constant 13.
As shown in FIG. 5B , the first mask 25 is then etched by using the second mask 21 comprising a silicon nitride film (or a metallic compound film). In this step, because the second film having a low dielectric constant 14 is formed with an organic film, the first film having a low dielectric constant 13 comprising an inorganic film is etched with the second film having a low dielectric constant 14 as an etching mask, so as to form via holes 26. In this etching step, octafluorobutane (C4F8) and carbon monoxide (CO), for example, are used as an etching gas.
As shown in FIG. 5C , the second film having a low dielectric constant 14 is etched by using the second mask 21 as an etching mask to form wiring grooves 27. The etching conditions in this step are the same as the conditions for etching the second film having a low dielectric constant 14. In this etching step, since the first film having a low dielectric constant 13 comprises an inorganic film, the etching is stopped at the upper surface of the first film having a low dielectric constant 13.
While not shown in the figure, wiring is formed in the wiring grooves 27 via a barrier metal layer, and plugs are formed in the via holes 26 via the barrier metal layer, in the same manner as described with reference to FIGS. 4G and 4H for the first embodiment.
In the second embodiment, as similar to the first embodiment, the process comprising from the step of forming the inter level dielectric 12 to the step of forming the wiring and the plugs may be repeated to form a multi-layer wiring. The inter metal dielectric 52 among the wiring 53 may be formed with an organic film, such as a xerogel film or a fluorine resin film, by the similar process as the foregoing.
In the descriptions in the foregoing, while an example is described, in which the inter level dielectric 12 is formed on the underlayer substrate 11 having semiconductor elements formed therein, the production process can be applied to the case where the inter level dielectric 12, the via holes 26, the wiring grooves 27, the wiring 33 and the plugs 34 having the constitution described above are formed on a substrate having no semiconductor element.
According to the second embodiment of the process for producing a semiconductor device of the invention, the same function and effect as the first embodiment of the process for producing a semiconductor device can be obtained.
A third embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 6A to 6F. In FIGS. 6A to 6F, the same symbols are attached to the same constitutional components as in FIGS. 3A to 3F.
As shown in FIG. 6A , an underlying substrater 11 comprises, for example, a substrate 51 having thereon transistors (not shown in the figure), and an inter metal dielectric 52 covering thereon, in which wiring 53 is formed. A first film having a low dielectric constant 13 to be a lower layer of an inter level dielectric 12 is formed to a thickness of, for example, from 300 to 800 nm on the underlying substrate 11. The first film having a low dielectric constant 13 becomes an inter level dielectric (ILD) between wiring layers, and can be formed with an organic film having a specific inductive capacity of about 2.5. For example, it can be formed with the same material as described for the first embodiment in the same film forming method as described therefor.
An intermediate film 41 to be an etching mask is formed with, for example, a silicon oxide film on the first film having a low dielectric constant 13. The method for forming the same may be the same forming method of the silicon oxide film as described for the first embodiment.
A second film having a low dielectric constant 14 to be an upper layer of the inter level dielectric 12 is formed to a thickness, for example of 400 nm on the intermediate film 41. The second film having a low dielectric constant 14 is formed with a fluorine resin. Examples of the film include a fluorocarbon film, such as a cyclic fluorine resin, polytetrafluoroethylene (PTFE), amorphous PTFE (for example, Teflon AF, a trade name, produced by Du Pont Corp.), fluorinated aryl ether and fluorinated polyimide. Alternatively, a xerogel (for example, porous silica) may be employed. The method for forming the fluorine resin film may be the same forming method as described for the first embodiment. Alternatively, the second film having a low dielectric constant 14 is formed with a xerogel film. The method for forming the xerogel film may be the same forming method as described for the first embodiment.
According to the manner described in the foregoing, the inter level dielectric 12 comprising the first film having a low dielectric constant 13, the intermediate film 41 and the second film having a low dielectric constant 14 is formed on the underlying substrate 11.
As shown in FIG. 6B , a first film 15 for forming a first mask as an inorganic mask is formed with a silicon oxide film having a thickness of from 50 to 300 nm on the inter level dielectric 12, i.e., on the second film having a low dielectric constant 14. A second film 16 for forming a second mask is formed with a silicon nitride film having a thickness of from 50 to 150 nm. The film forming method of these films may be the same forming method as described for the first embodiment.
Before forming the silicon oxide film, it is preferred that a film having a larger silicon content than the silicon nitride film, the amorphous silicon, the silicon nitride oxide film or the stoichiometric amount is formed, depending on necessity, particularly in the case where the oxidation of the second film having a low dielectric constant 15 causes a problem. That is, a CVD film is formed under a reductive atmosphere. The film thickness is preferably as thin as possible, and is generally about 10 nm. As described herein, the first film 15 is formed with a silicon oxide film that is excellent in light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment, and the second film 16 is also formed with a silicon nitride film having light transmissibility in a wavelength range (for example, from 200 to 1,000 nm) used for alignment.
As shown in FIG. 6C , a resist film 17 is formed on the second film 16 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 17 is patterned by a lithography technique to form openings 18 for forming wiring grooves.
Subsequently, the second film 16 is etched by using the resist film 17 as an etching mask to form openings 19 for forming wiring grooves, so as to form a second mask 21 to be an etching mask for forming wiring grooves in the inter level dielectric 12. The etching step may be conducted in the same manner as for the first embodiment. Thereafter, the resist film 17 is removed by ashing. FIG. 6C shows the state before removing the resist film 17.
As shown in FIG. 6D , a resist film 22 is formed on the second film 16 and the first film 15 by an ordinary resist coating technique (for example, a spin coating method). Thereafter, the resist film 22 is patterned by a lithography technique to form openings 23 for forming via holes at positions within the openings 19 for forming the wiring grooves from the plan view of the second film 16. Even when deviation occurs on aligning the masks, it is necessary that at least a part of the opening 23 overlaps the opening 19.
Subsequently, only the first film 15 is etched by using the resist film 22 as an etching mask to form openings 24 for forming via holes in the inter level dielectric 12, so as to form a first mask 25 to be an etching mask for forming the via holes in the inter level dielectric 12.
The second film having a low dielectric constant 14 of the inter level dielectric 12 is etched by using an ordinary etching apparatus using the first mask 25 as an etching mask. As the etching conditions, for example, nitrogen is used as an etching gas, and ammonia and a hydrogen gas may also be used depending on necessity. In this etching step, a fluorine carbide series gas and carbon monoxide are not necessary. Because the intermediate film 41 comprising a silicon oxide film is present as an underlayer of the second film having a low dielectric constant 14, the etching is stopped at the intermediate film 41. In the etching step, the resist film 22 is etched and completely removed when the second film having a low dielectric constant 14 comprising an organic film is etched. Therefore, there is no necessity to conduct resist ashing in this stage.
As shown in FIG. 6E , the first mask 25 and the intermediate film 41 are etched by using an ordinary etching apparatus using the second mask 21 and the second film having a low dielectric constant 14 as an etching mask. That is, the first mask 25 is etched as transferring the openings 19 formed in the second mask 21 for forming the wiring grooves, and openings 42 for forming via holes in the intermediate film 41 are formed by etching. As the etching conditions, for example, octafluorobutane (C4F8) (5 cm3/min), carbon monoxide (5 cm3/min) and argon (20 cm3/min) are used as an etching gas, and an RF plasma is set at 600 W.
As shown in FIG. 6F , by using the first mask 25 (the second mask 21) and the intermediate film 41 as an etching mask, the second film having a low dielectric constant 14 and the first film having a low dielectric constant 13 are etched, to form wiring grooves 27 in the second film having a low dielectric constant 14, and simultaneously to form via holes 26 in the first film having a low dielectric constant 13. As the etching gas in this etching step, nitrogen (N2) is used, and ammonia and a hydrogen gas may also be used depending on necessity.
While not shown in the figure, wiring comprising metal is formed in the wiring grooves 27 via a barrier signal metal layer, and plugs comprising metal are formed in the via holes 26 via the barrier metal layer, in the same manner as described with reference to FIGS. 4G and 4H .
According to the third embodiment described with reference to FIGS. 6A to 6F, the same function and effect as the first embodiment described with reference to FIGS. 3A to 3F can be obtained.
The intermediate film 41 may also be formed with a silicon nitride oxide film or a silicon nitride film. Alternatively, it may be formed with an organic film that becomes an etching mask with respect to the first film having a low dielectric constant 13 and becomes an etching stopper with respect to the second film having a low dielectric constant 14.
The xerogel film, the fluorine resin film and the other organic films are being employed in the wiring structure for the object of suppressing the wiring capacitance increasing with the scale down. In this case, the organic film may be employed as a material having a specific inductive capacitance of 3 or less, the fluorine resin may be employed as an organic film material having a specific inductive capacitance of 2.5 or less, and the xerogel film, which is a gel having a network structure containing no water, may be employed as a material having a specific inductive capacitance of 2.5 or less.
Among the xerogels described in the foregoing, a film that can be used in a semiconductor device includes a silica series gel. For example, Nanoporous Silica produced by Nanoglass LLC can be used. However, the xerogel film of this type is inferior in mechanical strength, heat conductivity, heat resistance, water resistance and adhesiveness in comparison to the conventional inter level dielectric. In particular, the heat conductivity is remarkably poor as is from 1/10 to 1/100 of the organic film.
On the other hand, as the fluorine resin, commercial products, such as a film formed by plasma CVD (reported by NEC Corp. in IEDM (International Electron Devices Meeting) on 1997), Teflon (produced by Du Pont Corp.) and fluorinated polyimide (produced by Du Pont Corp.) have been developed. As those under development, there are a vapor deposition film of fluorinated Parylene and a copolymer of a fluorine resin and silica. However, these films are inferior in mechanical strength, heat conductivity, heat resistance and adhesiveness in comparison to the organic polymer having a specific inductive capacity of 2.5 or more.
Under the circumstances, the invention employs a combination of a xerogel film and an organic film having a better film property than the xerogel film, or a combination of a fluorine resin film and an organic film having a better film property than the fluorine resin film, as described in the embodiments above, so as to realize to form a highly reliable wiring structure.
That is, the xerogel film or the fluorine resin film is used only in the part between the wirings, at which the wiring capacitance is increased by the scale down, and the other parts are formed with the organic film or the inorganic film having a low dielectric constant. Specifically, in a semiconductor device having the minimum interval of wiring, in particular, one of a design rule of 0.18 μm or less, the xerogel film or the fluorine resin film is applied to the part where the wiring interval is 0.3 μm or less because the wiring capacity is remarkably increased at the part where the wiring interval is 0.3 μm or less. According to this, an effect of decreasing the wiring capacitance can be obtained. On the other hand, there is no large influence at the part where the wiring interval is larger than 0.3 μm (for example, one between wiring layers vertically stacked). Therefore, it is sufficient to use an organic film having a specific inductive capacity of 3 or less at the part where the wiring interval exceeds 0.3 μm.
A fourth embodiment of the process for producing a semiconductor device according to the invention will be described below with reference to the process diagram shown in FIGS. 7A to 7I.
As shown in FIG. 7A , a substrate 60 is constituted, for example, by forming a semiconductor element, such as a transistor, on a semiconductor substrate, and then forming wiring and dielectrics. A passivation film 61 is formed with a material, by which the wiring material is not diffused, such as a silicon nitride film, having a thickness of about 50 nm on the uppermost layer of the substrate 60.
Thereafter, a first inter level dielectric 62, in which a via hole is formed, is formed with a silicon oxide series material, such as a silicon oxide (SiO2) film (an inorganic film) having a thickness of 500 nm, and then a second inter level dielectric 63, in which wiring is formed, is formed with an organic material, such as a polyaryl ether film having a thickness of 500 nm. Subsequently, a first film 64 for forming a first mask is formed with a silicon oxide film having a thickness of 100 nm, and then a second film 65 for forming a second mask is formed with a silicon nitride film having a thickness of 100 nm.
As shown in FIG. 7B , a resist mask 81 for forming a wiring groove is formed on the second film 65 by conducting an ordinary resist coating process and an ordinary lithography process. In the resist mask 81, an opening 82 for forming the wiring groove is formed.
Subsequently, as shown in FIG. 7C , the first film 65 is etched by using the resist mask 81 (see FIG. 7B ) to open a wiring groove pattern 66 for forming the wiring groove, so as to form a second mask 67. In this etching step, an ordinary parallel flat palate type plasma etching apparatus is used, and trifluoromethane (CHF3), argon (Ar) and oxygen (O2) are used as an etching gas. The substrate temperature is 0° C. Thereafter, the resist mask 81 (see FIG. 7B ) is removed.
As shown in FIG. 7D , a resist mask 83 used for forming a via hole is formed on the second mask 67 and the wiring groove pattern 66 by again conducting an ordinary resist coating process and an ordinary lithography process. In the resist mask 83, an opening 84 for forming the via hole is formed in such a manner that it at least overlaps the wiring groove pattern 66.
As shown in FIG. 7E , the first film 64 is etched by using the resist mask 83 as an etching mask to form a via hole pattern 68 for forming the via hole, so as to form a first mask 69. In etching of the first film 64, an ordinary parallel flat palate type plasma etching apparatus is used, and octafluorobutane (C4F8), argon (Ar) and oxygen (O2) are used as an etching gas. The substrate temperature is 0° C.
As shown in FIG. 7F , the second inter level dielectric 63 is etched by using the first mask 69 as an etching mask to extend the via hole pattern 68. In this etching step, the resist mask 83 is simultaneously etched and removed. In the etching step of the second inter level dielectric 63, an ordinary high-density plasma etching apparatus, and ammonia (NH3) is used as an etching gas. The substrate temperature is −20° C.
Subsequently, as shown in FIG. 7G , the wiring groove pattern 66 is extended to the first mask 69 by using the second mask 67 as an etching mask. At the same time, the first inter level dielectric 62 is etched by using the second inter level dielectric 63 as an etching mask to form a via hole 70. In this etching step, an ordinary parallel flat palate type plasma etching apparatus is used, and octafluorobutane (C4F8), argon (Ar) and oxygen (O2) are used as an etching gas. The substrate temperature is set at 0° C.
As shown in FIG. 7H , the second inter level dielectric 63 is etched by using the first mask 69 as an etching mask to form a wiring groove 71. In the etching step, an ordinary high-density plasma etching apparatus, and ammonia (NH3) is used as an etching gas. The substrate temperature is −100° C.
Thereafter, as shown in FIG. 7I , the passivation film 61 exposed at the bottom of the via hole 70 is etched. At this time, the second mask 67 (see FIG. 7H ) comprising the same material as the passivation film is also etched and removed. In this etching step, in order to selectively conduct anisotropic etching of the silicon nitride film, an ordinary high-density plasma etching apparatus is used, and sulfur hexafluoride (SF6) is used as an etching gas. The substrate temperature is 0° C. As a result, the wiring groove 71 is formed in the second inter level dielectric 63, and the via hole 70 is formed in the first inter level dielectric 62 and the passivation film 61 as being connected to the bottom of the wiring groove 71.
While a silicon oxide (SiO2) film is used as the first inter level dielectric 62 in this embodiment, silicon oxide fluoride (SiOF), for example, may also be used.
While the second mask layer 65 is formed with a silicon nitride film, it may be formed with a high melting point metal film or a high melting point metal compound film, such as a titanium nitride film. That is, any material may be used as far as the material has etching selectivity to the silicon oxide series material. It is preferred to use a film having light transmissibility, by which optical alignment can be conducted.
In the fourth embodiment described with reference to FIGS. 7A to 7I, while an example is described, in which the first and second inter level dielectrics 62 and 63 are formed on the substrate 60 having semiconductor elements formed therein, the production process described with reference to 7A to 7I can be applied to the case where the first and second inter level dielectrics 62 and 63, the via hole 70 and the wiring groove 71 are formed on a substrate having no semiconductor element.
The fourth embodiment of the process for producing a semiconductor device comprises a step of forming, on the second inter level dielectric 63, the first mask 69 to be an etching mask for etching the first and second inter level dielectrics 62 and 63, and a step of forming, on the first mask 69, the second mask 67, which comprises a material different from the first mask 69, to be an etching mask for etching the second inter level dielectric 63. Therefore, it is possible that the first and second inter level dielectrics 62 and 63 are etched by using the first mask 69 as an etching mask to form the via hole 70, and then the second inter level dielectric 63 is etched by using the second mask 67 having the wiring groove pattern 66, which is different from the first mask 69, as an etching mask to form the wiring groove 71.
Because the second inter level dielectric 63, which becomes an inter level dielectric between wiring in the same wiring layer, is formed with a polyaryl ether film, which is an organic polymer film, the dielectric constant between the wirings is decreased in comparison to the case where the second inter level dielectric 63 is formed with a silicon oxide series material, and thus the wiring capacitance is also decreased in comparison to the case where the second inter level dielectric 63 is formed with a silicon oxide series material.
Furthermore, the resist process (a step of patterning a resist film) used for forming the first and second masks 69 and 67 can be conducted under the condition in that the second inter level dielectric 63 is not exposed. That is, the first film 64 is formed as an underlayer layer in the resist process for forming the second mask 67, and the first film 64 covers the second inter level dielectric 63 in the resist process for forming the first mask 69. Therefore, the restoration treatment of the resist can be conducted without exposing the second inter level dielectric 63, i.e., an organic film, in which the resist films 81 and 83 formed in the resist processes can be removed, and the resist films 81 and 83 are again formed and patterned. Furthermore, because the resist film 83 to be an etching mask for forming the first mask 69 can be removed simultaneously with the etching of the second inter level dielectric 63, the operation of removing the resist film 83 is not necessary. Therefore, the process can be simplified.
In the resist process for forming the via hole pattern 68 for forming the via hole 70 in the first film 64, i.e., in the step of forming the opening 84 in the resist film 83, even when misalignment occurs to form the opening 84 in the resist film 83 deviating from the wiring groove pattern 66 formed in second mask 67, a via hole pattern (not shown in the figure) to be a pattern for forming the via hole also in the second mask 67 can be formed. The detail of this process will be described below with reference to FIGS. 8A to 8F. In each of FIGS. 8A to 8F, a plan view for the arrangement is shown in the upper part, and a cross sectional view is shown in the lower part.
As shown in FIG. 8A , an opening 84 formed in a resist film 83 for forming a via hole pattern is formed deviating from a wiring groove pattern 66 formed in a second mask 67. Even in such a case, by using the resist film 83 as an etching mask, the second mask 67 is etched, and further a first film 64 is etched, to form a via hole pattern 68, so as to form a first mask 69, as shown in FIG. 8B. By this step, the wiring groove pattern 66 and the via hole pattern 68 are formed in the second mask 67.
As shown in FIG. 8C , the second inter level dielectric 63 is then etched by using the first mask 69 as an etching mask to form the via hole pattern 68. Therefore, the via hole pattern 68 having the opening area that conforms to its design can be formed. In this etching step, the resist mask 83 (see FIG. 8B ) is simultaneously etched and removed.
Subsequently, as shown in FIG. 8D , the wiring groove pattern 66 is extended to the first mask 69 by using the second mask 67 as an etching mask. At the same time, the first inter level dielectric 62 is etched by using the second inter level dielectric 63 as an etching mask to form a via hole 70. As a result, because the via hole pattern 68 formed in the second inter level dielectric 63 is formed to have the opening area that conforms to its design, the via hole 70 is formed to have the opening area that conforms to its design.
As shown in FIG. 8E , the second inter level dielectric 63 is then etched by using the first mask 69 as an etching mask to form a wiring groove 71. Thereafter, as shown in FIG. 8F , the passivation film 61 exposed at the bottom of the via hole 70 is etched. At this time, the second mask 67 (see FIG. 8E ) comprising the same material as the passivation film is also etched and removed. As a result, the wiring groove 71 is formed in the second inter level dielectric 63, and the via hole 70 is formed in the first inter level dielectric 62 and the passivation film 61 as being connected to the bottom of the wiring groove 71. As described in the foregoing, the via hole pattern 68 having an opening area that conforms to its design is formed in the second inter level dielectric 63, and the via hole 70 is not filled with the inter level dielectric after forming the via hole 70. Therefore, the via hole 70 having a narrowed opening area as in the case of FIGS. 2A to 2F is not formed.
In the embodiment described herein, the opening area of the via hole can be ensured even when the via hole pattern deviates from the wiring groove pattern due to misalignment occurring on forming the via hole pattern. However, according to the process for producing a semiconductor device of the invention, the effect of ensuring the opening area of the via hole can be obtained in any case where the wiring groove pattern and the via hole pattern relatively deviate from each other.
Furthermore, the first film 65 to be the first mask 69 is formed with a material having light transmissibility, such as a silicon oxide film used herein, and the second film 65 to be the second mask is formed with a material having light transmissibility, such as a silicon nitride film used herein. Therefore, in the exposure step hereafter, the mask alignment to align the position of the mask to the underlayer can be conducted by alignment using light or alignment using an image processing. It has been known that a silicon oxide film and a silicon nitride film transmit light in the wavelength region of from 200 to 1,000 nm used for alignment.
Moreover, an etching stopper layer having a high dielectric constant (for example, a silicon nitride film, a silicon oxide film or a silicon oxide nitride film), which has been conventionally used, is not necessary by utilizing the difference in characteristics of the materials between the first inter level dielectric 62 and the second inter level dielectric 63. For example, when the condition in that the second inter level dielectric 63 (an organic film) is etched but the first inter level dielectric 62 is not etched is selected, the wiring grooves 71 can be formed in the second inter level dielectric 63 to be a wiring layer with good controllability. When the etching for forming the via holes 70 is conducted, the wiring groove pattern 66 is extended to the first mask 69 comprising a silicon oxide film, and at the same time, the first inter level dielectric 62 comprising a silicon oxide film is etched as described in the foregoing.
According to the invention described in the foregoing, the process comprises the step of forming, on the inter level dielectric, the first mask to be an etching mask for etching the inter level dielectric, and a step of forming, on the first mask, the second mask to be an etching mask for etching the inter level dielectric, the second mask comprising a material different from the first mask. Therefore, the inter level dielectric is etched by using the first mask as an etching mask to form the via holes, and then the inter level dielectric is etched by using the second mask as an etching mask to a pattern different from the first mask, to form the wiring grooves.
Furthermore, according to the production process, in which the upper layer of the inter metal dielectric between the wirings in the same wiring layer is formed with a xerogel film or a fluorine resin film, the wiring capacitance can be reduced. When an organic film or an inorganic film is used only in the inter level dielectric between the wirings layer among the inter level dielectrics, deterioration of the mechanical strength of the whole inter level dielectrics can be suppressed even when the inter level dielectric between the wirings is formed with a xerogel or a fluorine resin. Therefore, a semiconductor device combining copper wiring, a fluorine resin and an organic film, or a semiconductor device combining copper wiring, a xerogel and an organic film can be formed without deterioration of the yield.
In the resist process for forming the second mask, the first film is formed on the underlayer, and in the resist process for forming the first mask, the first film covers the inter level dielectric. Therefore, the resist processes for forming the first and second masks can be conducted under the condition in that the inter level dielectric is not exposed, and thus the restoration treatment of the resist film can be conducted in the resist process.
Even when misalignment occurs on forming the first mask having a pattern for forming the via hole, the pattern for forming the via hole can also be formed in the second mask. Therefore, the narrowing of the opening area of the via hole described in FIGS. 2A to 2F does not occur.
By forming the first mask and the second mask with a material having light transmissibility, the mask alignment in the exposure step of the lithography process conducted after forming the film for forming the first mask and the film for forming the second mask can be conducted in the same alignment method as the conventional process.
Claims (11)
1. A process for producing a semiconductor device comprising an inter level dielectric comprising a xerogel film or an organic film,
said process comprising
a step of forming on said inter level dielectric, a first light transmissible mask to be an etching mask for etching said inter level dielectric;
a step of forming, on said first mask, a second light transmissible mask comprising a different material from said first mask to be an etching mask for etching said inter level dielectric, said second light transmissible mask being formed with a silicon nitride;
a step of forming, on said second light transmissible mask, a first resist film that is used as a mask for etching said second light transmissible film;
removing said first resist film;
a step of forming, on said first and second light transmissible masks, a second resist film for etching said first light transmissible mask, and first and second levels of said inter level dielectric; and
removing said second resist film.
2. A process for producing a semiconductor device as claimed in claim 1 , wherein
a pattern for forming a wiring groove is formed in said second mask, and
a pattern for forming a via hole is formed in said first mask in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove.
3. A process for producing a semiconductor device as claimed in claim 2 , wherein a method for forming a pattern for forming a wiring groove in said second mask, and forming a pattern for forming a via hole in said first mask in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove comprises
a step of forming a first film for forming said first mask on said inter level dielectric, and then forming a second film for forming said second mask on said first film;
a step of forming said pattern for forming a wiring groove in said second film to form said second mask; and
a step of forming said pattern for forming a via hole in said first film in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove, to form said first mask.
4. A process for producing a semiconductor device as claimed in claim 1 , wherein
a lower layer of said inter level dielectric between wiring layers is formed with an organic film, and
an upper layer of said inter level dielectric between wiring of the same wiring layer is formed with a xerogel film or an organic film.
5. A process for producing a semiconductor device as claimed in claim 4 , wherein
a pattern for forming a wiring groove is formed in said second mask, and
a pattern for forming a via hole is formed in said first mask in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove.
6. A process for producing a semiconductor device as claimed in claim 5 , wherein a method for forming a pattern for forming a wiring groove in said second mask, and forming a pattern for forming a via hole in said first mask in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove comprises
a step of forming a first film for forming said first mask on said inter level dielectric, and then forming a second film for forming said second mask on said first film;
a step of forming said pattern for forming a wiring groove in said second film to form said second mask; and
a step of forming said pattern for forming a via hole in said first film in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove, to form said first mask.
7. A process for producing a semiconductor device as claimed in claim 6 , wherein said process comprises
after forming said first mask,
a step of continuously etching said inter level dielectric by using a resist film used as an etching mask for forming said first mask and said first mask as an etching mask, to form a via hole; and
a step of forming a wiring groove in said first mask and said upper layer of said inter level dielectric by etching using said second mask.
8. A process for producing a semiconductor device as claimed in claim 1 , wherein
a lower layer of said inter level dielectric between wiring layers is formed with an inorganic film, and
an upper layer of said inter level dielectric between wiring of the same wiring layer is formed with an organic film.
9. A process for producing a semiconductor device as claimed in claim 8 , wherein
a pattern for forming a wiring groove is formed in said second mask, and
a pattern for forming a via hole is formed in said first mask in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove.
10. A process for producing a semiconductor device as claimed in claim 9 , wherein a method for forming a pattern for forming a wiring groove in said second mask, and forming a pattern for forming a via hole in said first mask in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove comprises
step of forming a first film for forming said first mask on said inter level dielectric, and then forming a second film for forming said second mask on said first film;
a step of forming said pattern for forming a wiring groove in said second film to form said second mask; and
a step of forming said pattern for forming a via hole in said first film in such a manner that said pattern for forming a via hole at least overlaps said pattern for forming a wiring groove, to form said first mask.
11. A process for producing a semiconductor device as claimed in claim 10 , wherein said process comprises
after forming said first mask,
a step of forming an opening for forming a via hole in said upper layer of said inter level dielectric by using said first mask as an etching mask;
a step of forming an opening for forming a wiring groove in said first mask by etching using said second mask, and forming said via hole in said lower layer of said inter level dielectric by using said upper layer of said inter level dielectric as a mask; and
a step of forming said wiring groove in said upper layer of said inter level dielectric by using said second mask as an etching mask.
Priority Applications (1)
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US10/954,148 USRE40748E1 (en) | 1999-03-15 | 2004-09-30 | Process for producing semiconductor device |
Applications Claiming Priority (5)
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JP6778399 | 1999-03-15 | ||
JP14780099 | 1999-05-27 | ||
JP34963099A JP3436221B2 (en) | 1999-03-15 | 1999-12-09 | Manufacturing method of semiconductor device |
US09/525,265 US6593246B1 (en) | 1999-03-15 | 2000-03-14 | Process for producing semiconductor device |
US10/954,148 USRE40748E1 (en) | 1999-03-15 | 2004-09-30 | Process for producing semiconductor device |
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US09/525,265 Reissue US6593246B1 (en) | 1999-03-15 | 2000-03-14 | Process for producing semiconductor device |
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USRE40748E1 true USRE40748E1 (en) | 2009-06-16 |
Family
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US09/525,265 Ceased US6593246B1 (en) | 1999-03-15 | 2000-03-14 | Process for producing semiconductor device |
US10/954,148 Expired - Lifetime USRE40748E1 (en) | 1999-03-15 | 2004-09-30 | Process for producing semiconductor device |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
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US09/525,265 Ceased US6593246B1 (en) | 1999-03-15 | 2000-03-14 | Process for producing semiconductor device |
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JP (1) | JP3436221B2 (en) |
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Also Published As
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JP3436221B2 (en) | 2003-08-11 |
JP2001044189A (en) | 2001-02-16 |
US6593246B1 (en) | 2003-07-15 |
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