WO2022203057A1 - Detecting element and method for manufacturing same, and detecting system - Google Patents
Detecting element and method for manufacturing same, and detecting system Download PDFInfo
- Publication number
- WO2022203057A1 WO2022203057A1 PCT/JP2022/014522 JP2022014522W WO2022203057A1 WO 2022203057 A1 WO2022203057 A1 WO 2022203057A1 JP 2022014522 W JP2022014522 W JP 2022014522W WO 2022203057 A1 WO2022203057 A1 WO 2022203057A1
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- WO
- WIPO (PCT)
- Prior art keywords
- film
- piezoelectric
- film portion
- thin film
- piezoelectric film
- Prior art date
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 238000000034 method Methods 0.000 title description 22
- 239000010408 film Substances 0.000 claims abstract description 418
- 239000010409 thin film Substances 0.000 claims abstract description 90
- 238000003780 insertion Methods 0.000 claims abstract description 63
- 230000037431 insertion Effects 0.000 claims abstract description 63
- 239000000758 substrate Substances 0.000 claims abstract description 42
- 230000008859 change Effects 0.000 claims abstract description 15
- 238000001514 detection method Methods 0.000 claims description 88
- 239000003795 chemical substances by application Substances 0.000 claims description 18
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 14
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 14
- 239000002904 solvent Substances 0.000 claims description 12
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 9
- 230000007613 environmental effect Effects 0.000 claims description 6
- 230000002093 peripheral effect Effects 0.000 abstract description 5
- 239000010410 layer Substances 0.000 description 34
- 238000002474 experimental method Methods 0.000 description 27
- 230000001681 protective effect Effects 0.000 description 20
- 230000008878 coupling Effects 0.000 description 14
- 238000010168 coupling process Methods 0.000 description 14
- 238000005859 coupling reaction Methods 0.000 description 14
- 238000010586 diagram Methods 0.000 description 14
- 238000005530 etching Methods 0.000 description 14
- 238000012986 modification Methods 0.000 description 11
- 230000004048 modification Effects 0.000 description 11
- 238000005516 engineering process Methods 0.000 description 10
- 238000004544 sputter deposition Methods 0.000 description 9
- 238000001771 vacuum deposition Methods 0.000 description 9
- 238000005229 chemical vapour deposition Methods 0.000 description 8
- 238000004364 calculation method Methods 0.000 description 7
- 239000011651 chromium Substances 0.000 description 7
- 238000000206 photolithography Methods 0.000 description 7
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 6
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 6
- 229910052804 chromium Inorganic materials 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 229910052707 ruthenium Inorganic materials 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 229910052715 tantalum Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- 239000011800 void material Substances 0.000 description 4
- 229910052771 Terbium Inorganic materials 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 229910001849 group 12 element Inorganic materials 0.000 description 3
- 230000010365 information processing Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- VFUDMQLBKNMONU-UHFFFAOYSA-N 9-[4-(4-carbazol-9-ylphenyl)phenyl]carbazole Chemical compound C12=CC=CC=C2C2=CC=CC=C2N1C1=CC=C(C=2C=CC(=CC=2)N2C3=CC=CC=C3C3=CC=CC=C32)C=C1 VFUDMQLBKNMONU-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical compound C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229920002301 cellulose acetate Polymers 0.000 description 2
- 239000012461 cellulose resin Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229910021480 group 4 element Inorganic materials 0.000 description 2
- 229910021478 group 5 element Inorganic materials 0.000 description 2
- RBTKNAXYKSUFRK-UHFFFAOYSA-N heliogen blue Chemical compound [Cu].[N-]1C2=C(C=CC=C3)C3=C1N=C([N-]1)C3=CC=CC=C3C1=NC([N-]1)=C(C=CC=C3)C3=C1N=C([N-]1)C3=CC=CC=C3C1=N2 RBTKNAXYKSUFRK-UHFFFAOYSA-N 0.000 description 2
- 229920001519 homopolymer Polymers 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 2
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 229920000620 organic polymer Polymers 0.000 description 2
- -1 phenylene ether sulfone Chemical class 0.000 description 2
- 239000005360 phosphosilicate glass Substances 0.000 description 2
- 239000010948 rhodium Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 238000002336 sorption--desorption measurement Methods 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- KMXFZRSJMDYPPG-UHFFFAOYSA-N tetratetracontane Chemical compound CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC KMXFZRSJMDYPPG-UHFFFAOYSA-N 0.000 description 2
- TVIVIEFSHFOWTE-UHFFFAOYSA-K tri(quinolin-8-yloxy)alumane Chemical compound [Al+3].C1=CN=C2C([O-])=CC=CC2=C1.C1=CN=C2C([O-])=CC=CC2=C1.C1=CN=C2C([O-])=CC=CC2=C1 TVIVIEFSHFOWTE-UHFFFAOYSA-K 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- PZWLRLIAVLSBQU-UHFFFAOYSA-N 1,2-dioctyl-9h-fluorene Chemical class C1=CC=C2C3=CC=C(CCCCCCCC)C(CCCCCCCC)=C3CC2=C1 PZWLRLIAVLSBQU-UHFFFAOYSA-N 0.000 description 1
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 1
- HAZJTCQWIDBCCE-UHFFFAOYSA-N 1h-triazine-6-thione Chemical class SC1=CC=NN=N1 HAZJTCQWIDBCCE-UHFFFAOYSA-N 0.000 description 1
- STTGYIUESPWXOW-UHFFFAOYSA-N 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline Chemical compound C=12C=CC3=C(C=4C=CC=CC=4)C=C(C)N=C3C2=NC(C)=CC=1C1=CC=CC=C1 STTGYIUESPWXOW-UHFFFAOYSA-N 0.000 description 1
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- XMWRBQBLMFGWIX-UHFFFAOYSA-N C60 fullerene Chemical compound C12=C3C(C4=C56)=C7C8=C5C5=C9C%10=C6C6=C4C1=C1C4=C6C6=C%10C%10=C9C9=C%11C5=C8C5=C8C7=C3C3=C7C2=C1C1=C2C4=C6C4=C%10C6=C9C9=C%11C5=C5C8=C3C3=C7C1=C1C2=C4C6=C2C9=C5C3=C12 XMWRBQBLMFGWIX-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
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- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 239000005062 Polybutadiene Substances 0.000 description 1
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- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 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
- 238000013459 approach Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
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- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
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- 239000013626 chemical specie Substances 0.000 description 1
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- 150000001875 compounds Chemical class 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- XCJYREBRNVKWGJ-UHFFFAOYSA-N copper(II) phthalocyanine Chemical compound [Cu+2].C12=CC=CC=C2C(N=C2[N-]C(C3=CC=CC=C32)=N2)=NC1=NC([C]1C=CC=CC1=1)=NC=1N=C1[C]3C=CC=CC3=C2[N-]1 XCJYREBRNVKWGJ-UHFFFAOYSA-N 0.000 description 1
- NKZSPGSOXYXWQA-UHFFFAOYSA-N dioxido(oxo)titanium;lead(2+) Chemical compound [Pb+2].[O-][Ti]([O-])=O NKZSPGSOXYXWQA-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 229910003472 fullerene Inorganic materials 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- IBHBKWKFFTZAHE-UHFFFAOYSA-N n-[4-[4-(n-naphthalen-1-ylanilino)phenyl]phenyl]-n-phenylnaphthalen-1-amine Chemical compound C1=CC=CC=C1N(C=1C2=CC=CC=C2C=CC=1)C1=CC=C(C=2C=CC(=CC=2)N(C=2C=CC=CC=2)C=2C3=CC=CC=C3C=CC=2)C=C1 IBHBKWKFFTZAHE-UHFFFAOYSA-N 0.000 description 1
- 239000002120 nanofilm Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- SLIUAWYAILUBJU-UHFFFAOYSA-N pentacene Chemical compound C1=CC=CC2=CC3=CC4=CC5=CC=CC=C5C=C4C=C3C=C21 SLIUAWYAILUBJU-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920003227 poly(N-vinyl carbazole) Polymers 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 229920000052 poly(p-xylylene) Polymers 0.000 description 1
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- 239000004632 polycaprolactone Substances 0.000 description 1
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- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 229910052706 scandium Inorganic materials 0.000 description 1
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 230000008786 sensory perception of smell Effects 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 description 1
- 229930192474 thiophene Natural products 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 239000011135 tin Substances 0.000 description 1
- 229910001930 tungsten oxide Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/02—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by absorbing or adsorbing components of a material and determining change of weight of the adsorbent, e.g. determining moisture content
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/06—Forming electrodes or interconnections, e.g. leads or terminals
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/40—Piezoelectric or electrostrictive devices with electrical input and electrical output, e.g. functioning as transformers
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/853—Ceramic compositions
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/87—Electrodes or interconnections, e.g. leads or terminals
Definitions
- the present invention relates to a detection element, its manufacturing method, and a detection system, for example, a detection element having a resonator, its manufacturing method, and its detection system.
- Environmental sensors are known that detect changes in the environment, such as the concentration of specific atoms or molecules in a gas or liquid, temperature, or humidity, by detecting changes in the mass of a sensitive film.
- a detection system is known in which a sensitive film is provided on the upper electrode of a piezoelectric thin film resonator and changes in the environment are detected based on changes in resonance frequency due to changes in the mass of the sensitive film (for example, Patent Document 1).
- a piezoelectric thin film resonator has a structure in which a lower electrode and an upper electrode face each other with a piezoelectric film interposed therebetween. A region where the lower electrode and the upper electrode face each other with at least a portion of the piezoelectric film therebetween is a resonance region where elastic waves resonate. It is known to provide an insertion film in the piezoelectric film of a piezoelectric thin film resonator (for example, Patent Document 2).
- the characteristics of the resonator will not be stable. As shown in FIG. 17B of Patent Document 1, forming a dam using a protective film so as to surround the resonance region complicates the manufacturing process. Furthermore, the characteristics of the resonator may not stabilize when the sensing element is operated.
- the present invention has been made in view of the above problems, and aims to simplify the manufacturing process and stabilize the characteristics of the resonator.
- the present invention comprises a substrate, a piezoelectric film provided on the substrate, a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film therebetween, and the lower electrode with at least a portion of the piezoelectric film therebetween.
- a thin film portion provided between the lower electrode and the upper electrode in a resonance region defined by a region facing the upper electrode and inside the resonance region in plan view; a thick film portion that surrounds the thin film portion and is provided at the periphery of the resonance region and is thicker than the thin film portion; and a sensitive film provided in a region surrounded by the first steps, the detecting element having a resonant frequency that changes with changes in the environment.
- the sign of the temperature coefficient of the elastic constant of the thin film portion may be opposite to the sign of the temperature coefficient of the elastic constant of the piezoelectric film.
- the thick film portion may include a film having a Young's modulus smaller than the Young's modulus of the piezoelectric film.
- the piezoelectric film may be composed mainly of an aluminum nitride film, and the insertion film may be composed mainly of silicon oxide.
- the piezoelectric film includes a lower piezoelectric film provided on the lower electrode and an upper piezoelectric film provided on the lower piezoelectric film, and the insertion film comprises the lower piezoelectric film and the upper piezoelectric film. It can be configured to be provided between the piezoelectric film.
- the thickness of the thick film portion may be 1.5 times or more the thickness of the thin film portion.
- the temperature frequency coefficient of the resonance frequency of the detection element may be -20 ppm/K or more and 20 ppm/K or less.
- a second step is provided on the upper surface of the insertion film so that the upper surface of the thin film portion is recessed toward the front substrate from the upper surface of the thick film portion, and the upper surface of the piezoelectric film corresponds to the thin film portion.
- a third step is provided so that the upper surface of the piezoelectric film corresponding to the thick film portion is recessed toward the substrate side from the upper surface of the piezoelectric film corresponding to the thick film portion, and the first step is provided on the upper electrode corresponding to the thin film portion.
- An upper surface may be recessed toward the substrate from the upper electrode corresponding to the thick film portion.
- the slope of the first step may be gentler than the slope of the second step.
- the present invention is a detection system that detects changes in the environment based on the detection element and the signal output from the detection element.
- a plurality of the detection elements may be provided, and the sensitive films in at least two of the plurality of detection elements may be made of different materials.
- the present invention comprises a piezoelectric film provided on a substrate, a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film therebetween, and the lower electrode and the upper electrode with at least a portion of the piezoelectric film therebetween. is provided between the lower electrode and the upper electrode within the resonance region defined by the opposing regions, and surrounds the thin film portion and the resonance region in plan view with the thin film portion provided inside the resonance region.
- a step of fabricating a resonator comprising an insertion film comprising a thick film portion provided on the peripheral edge and thicker than the thin film portion; forming a sensitive film whose mass changes according to environmental changes in a region surrounded by a step defined by the thin film portion and the thick film portion provided on the upper surface of the upper electrode. is a manufacturing method.
- the step of forming the sensitive film may include a step of applying a solvent containing a sensitive agent.
- An object of the present invention is to simplify the manufacturing process and stabilize the characteristics of the resonator.
- FIG. 1(a) is a plan view of a detection element according to Example 1
- FIG. 1(b) is a cross-sectional view taken along the line AA of FIG. 1(a).
- 2A to 2D are cross-sectional views (Part 1) showing the method for manufacturing the detection element according to the first embodiment.
- 3A to 3C are cross-sectional views (part 2) showing the method for manufacturing the detection element according to the first embodiment.
- 4A to 4C are cross-sectional views (part 3) showing the method for manufacturing the detection element according to the first embodiment.
- FIGS. 5(a) to 5(c) are photographic images of the sensitive agent after application of each solution in Experiment 1, viewed from above.
- FIG. 6(a) to 6(c) are diagrams showing the thickness of the sensitive agent with respect to the position after application of each solvent in Example 1.
- FIG. FIG. 7 is a diagram showing the Q value with respect to the thickness of the sensitive film in Experiment 2.
- FIG. 8A to 8C are plan views of resonators A to C fabricated in Experiment 3.
- FIGS. 9(a) and 9(b) are diagrams showing impedance magnitudes
- FIG. 10 is a cross-sectional view showing an insertion membrane in Experiment 4.
- FIG. 10 is a cross-sectional view showing an insertion membrane in Experiment 4.
- FIG. 11(a) and 11( b ) are diagrams showing k2 and Qa, respectively, with respect to the thickness Ta of the thick film portion 28a in Experiment 4.
- FIG. 12 is a diagram showing the TCF with respect to the thickness Tb of the thin film portion in Experiment 4.
- FIG. 13 is a diagram showing changes ⁇ f in resonance frequency with respect to time in Experiment 5.
- FIG. 14 is an enlarged cross-sectional view showing an example of the steps of the piezoelectric film, the insertion film, the upper electrode and the sensitive film in Example 1.
- FIG. 15A and 15B are cross-sectional views of piezoelectric thin film resonators according to Modifications 1 and 2 of Example 1, respectively.
- FIG. 16 is a functional block diagram of a detection system according to a second embodiment;
- FIG. 1(a) is a plan view of the detection element 112 according to Example 1
- FIG. 1(b) is a cross-sectional view taken along the line AA in FIG. 1(a).
- the direction normal to the upper surface of the substrate 10 is defined as the Z direction
- the direction in which the lower electrode 12 is pulled out from the resonance region 50 is defined as the X direction
- the planar direction perpendicular to the X direction is defined as the Y direction.
- a gap 30 having a dome-shaped bulge is formed between the flat upper surface of the substrate 10 and the lower electrode 12.
- the dome-shaped bulge is, for example, a bulge having a shape in which the height of the gap 30 is small around the gap 30 and the height of the gap 30 increases toward the inside of the gap 30 .
- a piezoelectric film 14 is provided on the lower electrode 12 .
- An upper electrode 16 is provided on the piezoelectric film 14 .
- the resonance region 50 is defined by a region where the lower electrode 12 and the upper electrode 16 face each other with at least a portion of the piezoelectric film 14 interposed therebetween.
- the resonance region 50 has an elliptical shape, and is a region in which elastic waves in thickness longitudinal vibration mode or thickness shear vibration mode resonate.
- the piezoelectric film 14 includes a lower piezoelectric film 14a provided on the lower electrode 12 and an upper piezoelectric film 14b provided on the lower piezoelectric film 14a.
- An insertion film 28 is provided between the lower piezoelectric film 14 a and the upper piezoelectric film 14 b within the resonance region 50 .
- the thicknesses of the lower piezoelectric film 14a and the upper piezoelectric film 14b are substantially the same. Although the thicknesses of the lower piezoelectric film 14a and the upper piezoelectric film 14b do not have to be the same, by making them the same, the function of the insertion film 28 can be further exhibited.
- the insertion film 28 has a thin film portion 28b and a thick film portion 28a.
- the thick film portion 28a is thicker than the thin film portion 28b.
- the thin film portion 28 b is provided in a region 54 inside the resonance region 50 .
- the thick film portion 28 a is provided in at least a portion of the outer peripheral region 52 within the resonance region 50 .
- the inner area 54 is an area within the resonance area 50 and located inside the resonance area 50 in plan view.
- the outer peripheral region 52 is a region within the resonance region 50 , surrounds the inner region 54 , includes the outer periphery of the resonance region 50 and is along the outer periphery.
- the thick film portion 28 a surrounds at least a portion of the outer circumference of the thin film portion 28 b , includes the outer circumference of the resonance region 50 , and is provided along the outer circumference of the resonance region 50 .
- the planar shape of the thick film portion 28a is, for example, a ring shape or at least part of a ring.
- the thickness of the thin film portion 28b is approximately uniform, and the thickness of the thick film portion 28a is approximately uniform.
- a concave portion 26 corresponding to the film thickness difference between the thick film portion 28a and the thin film portion 28b is provided on the upper surface of the insertion film 28.
- FIG. A concave portion 27 defined by a concave portion 26 is formed on the upper surface of the piezoelectric film 14 .
- a recess 22 defined by recesses 26 and 27 is formed in the upper surface of upper electrode 16 . That is, the concave portion 22 is a region surrounded by the steps 23 defined by the thin film portion 28b and the thick film portion 28a.
- a sensitive film 24 is provided in the recess 27 .
- the height of the step 23 is D1.
- the upper surface of the sensitive film 24 is substantially flat.
- An insulating film may be provided as a protective film or a frequency adjusting film between the upper electrode 16 and the sensitive film 24 .
- a metal layer 20 is provided on the lower electrode 12 and the upper electrode 16 outside the resonance region 50 .
- the metal layer 20 is, for example, pads or wiring.
- the lower electrode 12 is provided with a hole 35 for etching the sacrificial layer. The hole 35 is connected to the air gap 30 .
- environmental changes refer to changes in the concentration of a specific substance in the gas or liquid surrounding the detection element 112, humidity, temperature, light intensity, or the like.
- substances such as specific atoms or molecules in gas or liquid are adsorbed on the sensitive film 24
- the mass of the sensitive film 24 increases and the resonance frequency of the detection element decreases.
- the humidity around the sensitive film 24 increases, water is adsorbed on the sensitive film 24 and the mass of the sensitive film 24 increases, so that the resonance frequency of the detection element 112 decreases.
- the temperature changes the adsorption/desorption characteristics of the sensitive film 24 for substances such as specific atoms or molecules change, and as a result, the mass of the sensitive film 24 changes.
- the resonance frequency of the detection element changes due to the temperature characteristics of the sensitive film 24 and the piezoelectric thin film resonator.
- the sensitive film 24 is irradiated with light such as ultraviolet rays
- the adsorption/desorption characteristics of the sensitive film 24 with respect to substances such as specific atoms or molecules change, and as a result, the mass of the sensitive film 24 changes, and the resonance frequency of the detection element changes. changes.
- the resonance frequency of the sensing element 112 changes due to changes in the environment. A change in the environment can be detected by a change in the resonant frequency of the sensing element 112 .
- the substrate 10 is, for example, a silicon substrate, a sapphire substrate, a quartz substrate, a glass substrate, a ceramic substrate or a GaAs substrate.
- the lower electrode 12 and the upper electrode 16 are made of, for example, ruthenium (Ru), chromium (Cr), aluminum (Al), titanium (Ti), copper (Cu), molybdenum (Mo), tungsten (W), tantalum (Ta), A single layer film of platinum (Pt), rhodium (Rh), iridium (Ir), or the like, or a laminated film thereof.
- the lower electrode 12 is, for example, a chromium film and a ruthenium film from the substrate 10 side
- the upper electrode 16 is, for example, a ruthenium film and a chromium film from the piezoelectric film 14 side.
- the piezoelectric film 14 is made of, for example, aluminum nitride (AlN) film, zinc oxide (ZnO) film, gallium nitride (GaN) film, lead zirconate titanate (PZT) film, lead titanate (PbTiO 3 ) film, lithium tantalate ( LiTaO 3 ) film or lithium niobate (LiNbO 3 ) film.
- the piezoelectric film 14 is mainly composed of aluminum nitride (AlN) whose main axis is the (002) direction, and may contain other elements to improve resonance characteristics or piezoelectricity.
- the piezoelectricity of the piezoelectric film 14 is improved. Therefore, the effective electromechanical coupling coefficient of the piezoelectric thin film resonator can be improved.
- Group 2 elements are, for example, calcium (Ca), magnesium (Mg), and strontium (Sr), and group 12 elements are, for example, zinc (Zn).
- Group 4 elements are, for example, titanium, zirconium (Zr) or hafnium (Hf).
- Group 5 elements are, for example, tantalum, niobium (Nb) or vanadium (V).
- the piezoelectric film 14 may contain aluminum nitride as a main component and may contain boron (B).
- the thin film portion 28b of the insertion film 28 has a temperature coefficient of elastic constant opposite in sign to the temperature coefficient of elastic constant of the piezoelectric film 14 .
- the thin film portion 28b is, for example, silicon oxide or a silicon oxide film containing impurities such as fluorine.
- At least part of the thick film portion 28a of the insertion film 28 includes a film of a material having a Young's modulus smaller than that of the piezoelectric film 14, such as a silicon oxide film, an aluminum film, a titanium film, a chromium film, a ruthenium film, or a tungsten film.
- the metal layer 20 is a low resistance film such as a gold film, copper film or aluminum film.
- the protective film or frequency adjustment film is, for example, a silicon oxide film, a silicon nitride film or an aluminum oxide film.
- the sensitive film 24 is, for example, an organic polymer film, an organic low-molecular film, or an inorganic film.
- organic polymer materials include polystyrene, polymethyl methacrylate, 6-nylon, cellulose acetate, poly-9,9-dioctylenefluorene, polyvinyl alcohol, polyvinylcarbazole, polyethylene oxide, polyvinyl chloride, poly-p- Homopolymers having a single structure such as phenylene ether sulfone, poly-1-butene, polybutadiene, polyphenylmethylsilane, polycaprolactone, polybisphenoxyphosphazene, and polypropylene, copolymers of two or more homopolymers, and these can be used.
- organic low-molecular-weight materials include tris(8-quinolinolato)aluminum (Alq3), naphthyldiamine ( ⁇ -NPD), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), CBP (4,4'-N,N'-dicarbazole-biphenyl), copper phthalocyanine, fullerene, pentacene, anthracene, thiophene, Ir(ppy(2-phenylpyridinato)) 3 , triazinethiol derivative, dioctylfluorene derivative, tetratetracontane, Parylene and the like can be used.
- Alq3 tris(8-quinolinolato)aluminum
- ⁇ -NPD naphthyldiamine
- BCP 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline
- CBP 4,4'
- inorganic materials include alumina, titania, vanadium pentoxide, tungsten oxide, lithium fluoride, magnesium fluoride, aluminum, gold, silver, tin, indium tin oxide (ITO), carbon nanotubes, sodium chloride, chloride Magnesium or the like can be used.
- the lower electrode 12 is a chromium film with a thickness of 70 nm and a ruthenium film with a thickness of 166 nm from the substrate 10 side.
- the lower piezoelectric film 14a is an aluminum nitride film with a thickness of 498 nm
- the upper piezoelectric film 14b is an aluminum nitride film with a thickness of 498 nm.
- the insertion film 28 is a silicon oxide (SiO 2 ) film, the film thickness of the thin film portion 28b is 73 nm, and the film thickness of the thick film portion 28a is 180 nm.
- the upper electrode 16 is a ruthenium film with a thickness of 166 nm and a chromium film with a thickness of 55 nm from the piezoelectric film 14 side.
- the sensitive film 24 is, for example, a cellulose resin (cellulose acetate) with a thickness of 80 nm.
- a silicon oxide film having a thickness of 70 nm may be provided between the upper electrode 16 and the sensitive film 24 as a protective film or a frequency adjusting film.
- the film thickness of each layer can be appropriately set to obtain desired resonance characteristics.
- FIG. 2(a) are cross-sectional views showing a method for manufacturing the detection element 112 according to Example 1.
- FIG. 2(a) a sacrificial layer 38 is formed on the substrate 10 having a flat top surface to form a void.
- the sacrificial layer 38 is, for example, a magnesium oxide (MgO) film, a zinc oxide (ZnO) film, a germanium (Ge) film, a silicon oxide (SiO 2 ) film, or a phosphosilicate glass (PSG) film.
- the thickness of the sacrificial layer 38 is, for example, 10-100 nm.
- the sacrificial layer 38 is deposited using a sputtering method, a vacuum deposition method, or a CVD (Chemical Vapor Deposition) method. After that, the sacrificial layer 38 is patterned into a desired shape using photolithography technology and etching technology.
- the shape of the sacrificial layer 38 is a shape corresponding to the planar shape of the air gap 30 and includes, for example, a region that becomes the resonance region 50 .
- the lower electrode 12 is formed on the sacrificial layer 38 and the substrate 10 as shown in FIG. 2(b).
- the lower electrode 12 is deposited using, for example, a sputtering method, a vacuum deposition method, or a CVD method. Thereafter, the lower electrode 12 is patterned into a desired shape using photolithography technology and etching technology.
- the lower electrode 12 may be formed by a lift-off method.
- a lower piezoelectric film 14a is formed on the lower electrode 12 and the substrate 10 using, for example, sputtering, vacuum deposition, or CVD.
- an insertion film 28 is formed on the lower piezoelectric film 14a.
- the insertion film 28 is patterned into a desired shape using photolithography technology and etching technology.
- the insertion film 28 may be formed by a lift-off method.
- a method for forming the thick film portion 28a and the thin film portion 28b in the insertion film 28 will be described.
- An insertion film having the thickness of the thick film portion 28a is formed on the lower piezoelectric film 14a by sputtering, vacuum deposition, or CVD. After that, the region of the insertion film that will become the thin film portion 28b is thinned by photolithography and etching. Thereby, the thick film portion 28a and the thin film portion 28b are formed.
- a first insertion film having the thickness of the thin film portion 28b is formed on the lower piezoelectric film 14a by sputtering, vacuum deposition, or CVD.
- a second insertion film having a desired pattern is formed on the first insertion film using a lift-off method.
- the insertion film 28 formed with the first insertion film and the second insertion film becomes the thick film portion 28a.
- the insertion film 28 formed with the first insertion film and not formed with the second insertion film becomes the thin film portion 28b.
- a concave portion 26 is formed in the upper surface of the insertion film 28 .
- the upper piezoelectric film 14b is formed on the lower piezoelectric film 14a and the insertion film 28, as shown in FIG. 3(a).
- the upper piezoelectric film 14b is formed using, for example, a sputtering method, a vacuum deposition method, or a CVD method.
- the piezoelectric film 14 is formed from the lower piezoelectric film 14a and the upper piezoelectric film 14b.
- a concave portion 27 corresponding to the concave portion 26 of the insertion film 28 is formed on the upper surface of the upper piezoelectric film 14b.
- the upper electrode 16 is formed on the upper piezoelectric film 14b.
- the upper electrode 16 is formed by sputtering, vacuum deposition, or CVD, for example.
- the upper electrode 16 is patterned into a desired shape using, for example, photolithography technology and etching technology.
- the upper electrode 16 may be formed by a lift-off method.
- a concave portion 22 surrounded by a step 23 is formed on the upper surface of the upper electrode 16 corresponding to the concave portion 26 on the upper surface of the insertion film 28 and the concave portion 26 on the upper surface of the upper piezoelectric film 14b.
- the piezoelectric film 14 is patterned into a desired shape using, for example, photolithography technology and etching technology.
- a metal layer 20 is formed on the lower electrode 12 and the upper electrode 16 outside the resonance region 50 .
- the metal layer 20 is formed using, for example, a sputtering method, a vacuum deposition method, and a lift-off method.
- an etchant is introduced into the sacrificial layer 38 under the lower electrode 12 through the hole 35 (see FIG. 1(a)). This removes the sacrificial layer 38 .
- a medium for etching the sacrificial layer 38 is preferably a medium that does not etch the material constituting the resonator other than the sacrificial layer 38 .
- the etching medium is preferably a medium in which the lower electrode 12 in contact with the etching medium is not etched.
- the stresses of the lower electrode 12, the piezoelectric film 14 and the upper electrode 16 are set to be compressive stress. Thereby, when the sacrificial layer 38 is removed, the lower electrode 12 bulges away from the substrate 10 on the opposite side of the substrate 10 . Thereby, a gap 30 having a dome-shaped bulge is formed between the lower electrode 12 and the substrate 10 .
- a sensitive film 24 is formed in the recess 22 on the upper surface of the upper electrode 16.
- the sensitive film 24 is formed by, for example, applying a solvent in which the material of the sensitive film 24 is dissolved, and then drying the solvent.
- the sensitive film 24 may be formed into a desired pattern using a sputtering method or a vacuum deposition method and a lift-off method.
- the detection element 112 according to Example 1 is manufactured.
- Experiment 1 Assuming that the sensitive film 24 is formed on the upper electrode 16, Experiment 1 below was performed. A solvent was prepared by dissolving a cellulose resin in 5 g of acetone as a solvent. About 2 ⁇ l (microliter) of the prepared solvent was applied onto a slide glass using a micropipette to prepare a sensitive agent 25 . The concentrations of cellulosic resin in the solvent for each sample are 0.1 wt%, 0.5 wt% and 1.0 wt%.
- FIGS. 5(a) to 5(c) are photographic images of the sensitive agent after application of each solution in Experiment 1, viewed from above.
- the area of the sensitive agent 25 does not change much between 0.5% by weight and 1.0% by weight, but the area of the sensitive agent 25 at 0.1% by weight does not change when viewed from above.
- the area of 25 is increased.
- the planar shape of the sensitive agent 25 becomes distorted.
- Lx and Ly be the dimensions of the sensitive agent 25 in the X and Y directions.
- FIGS. 6(a) to 6(c) are diagrams showing the thickness of the sensitive agent with respect to the position after application of each solvent in Example 1.
- the thickness Tmax is the maximum film thickness at the ends of the sensitive agent 25, and the thickness of the central portion of the sensitive agent 25 is Tc.
- the sensitizer 25 is thick at the ends and thin at the center. The thickness of the sensitive agent 25 was measured at multiple locations for each sample.
- Table 1 summarizes the dimensions Lx, Ly, thickness Tmax and Tc of each sensitizer 25 .
- Tmax and Tc indicate ranges of measurement results at multiple locations.
- Example 2 the Q value at the anti-resonance frequency was measured with respect to the thickness of the sensitive film 24 .
- the materials and dimensions of each layer are the same as those exemplified in the first embodiment when the resonance frequency is 2.4 GHz.
- FIG. 7 is a diagram showing the Q value with respect to the thickness of the sensitive film in Experiment 2.
- the Q factor Qa at the anti-resonance frequency becomes smaller as the sensitive film 24 becomes thicker.
- the Qa of the piezoelectric thin film resonator with the sensitive film 24 having a thickness of 156 nm is less than half the Qa of the piezoelectric thin film resonator without the sensitive film 24 .
- Qa becomes almost 0 and does not resonate.
- the thickness of the sensitive film 24 is preferably 500 nm or less, more preferably 200 nm or less.
- the planar shape of the sensitive film 24 becomes distorted as shown in FIGS.
- FIG. 8A to 8C are plan views of resonators A to C fabricated in Experiment 3.
- FIG. The area of the sensitive film 24 is hatched.
- FIG. 8( a ) in the resonator A, the sensitive film 24 is not provided on the upper electrode 16 .
- FIG. 8B in the resonator B, the sensitive film 24 is provided within the resonance region 50 on the upper electrode 16 .
- the sensitive film 24 is not provided in a region 58 on the extraction side of the resonance region 50, and the planar shape of the sensitive film 24 is distorted. As shown in FIG. 8C, in the resonator C, the sensitive film 24 is provided over the entire resonance region 50 on the upper electrode 16. As shown in FIG. 8C, in the resonator C, the sensitive film 24 is provided over the entire resonance region 50 on the upper electrode 16. As shown in FIG. 8C, in the resonator C, the sensitive film 24 is provided over the entire resonance region 50 on the upper electrode 16. As shown in FIG.
- FIGS. 9(a) and 9(b) are diagrams showing impedance magnitudes
- FIG. FIG. 9(b) is an enlarged view of FIG. 9(a).
- the peaks of the antiresonance frequency fa and the resonance frequency fr are duller, and the Q values are lower.
- the difference between the anti - resonance frequency fa and the resonance frequency fr is small, and the electromechanical coupling coefficient k2 is small.
- the provision of the sensitive film 24 reduces the Q value and the electromechanical coupling coefficient k2 .
- spurious 56 is observed between fa and fr.
- spurious 56 is not observed.
- the spurious is generated because the plane shape of the sensitive film 24 is distorted.
- the spurious 56 may be erroneously recognized as fr or fa when measuring fluctuations in the resonance frequency fr or anti-resonance frequency fa of the detection element.
- the sensitive film 24 is provided in the concave portion 22 on the upper surface of the upper electrode 16, it is possible to prevent the planar shape of the sensitive film 24 from becoming distorted. Thereby, the spurious 56 can be suppressed.
- Example 4 Similar to Example 1, resonators were fabricated by changing the thickness of the insertion film 28 .
- 10 is a cross-sectional view showing an insertion membrane in Experiment 4.
- FIG. 10 the thickness of the thick film portion 28a of the insertion film 28 is Ta, and the thickness of the thin film portion 28b is Tb.
- the thickness Td Ta-Tb was fixed at 107 nm.
- the materials and dimensions of other layers are the materials and dimensions exemplified for the piezoelectric thin film resonator with a resonance frequency of 2.4 GHz.
- FIG. 11(a) and 11( b ) are diagrams showing k2 and Qa, respectively, with respect to the thickness Ta of the thick film portion 28a in Experiment 4.
- FIG. 11A As shown in FIG . 11A, as the thickness Ta of the thick film portion 28a increases, the electromechanical coupling coefficient k2 decreases. As shown in FIG. 11B, as the thickness Ta increases, the Q factor Qa of the anti-resonance frequency increases. As described above, when the thickness Ta of the thick film portion 28a is increased, it is possible to suppress leakage of elastic waves from the resonance region 50 to the outside, thereby improving the Q value. However, the electromechanical coupling coefficient k2 becomes small.
- the electromechanical coupling coefficient k2 becomes smaller, the difference between the resonance frequency fr and the anti - resonance frequency fa becomes smaller.
- the difference between the resonance frequency fr and the anti-resonance frequency fa is small, the achievable bandwidth is limited, making it difficult to design the high-frequency filter.
- a piezoelectric thin film resonator having a small electromechanical coupling coefficient k2 cannot be used for a high frequency filter such as that disclosed in Patent Document 2 .
- a detector element may have a low k2 if the Q factor is high . Therefore, the thickness Ta can be increased.
- FIG. 12 is a diagram showing the TCF with respect to the thickness Tb of the thin film portion in Experiment 4.
- FIG. A temperature coefficient of frequency (TCF) is the temperature coefficient of the resonant frequency.
- the temperature coefficient of the elastic constant of the piezoelectric film 14 is negative, and the temperature coefficient of the elastic constant of the thin film portion 28b is positive. Therefore, TCF is negative if the thin film portion 28b is not provided.
- TCF is negative if the thin film portion 28b is not provided.
- the thickness Tb of the thin film portion 28b is increased, the TCF changes in the positive direction. By setting the thickness Tb to about 70 nm, the TCF can be made almost zero. Increasing the thickness Tb reduces the electromechanical coupling coefficient k2 .
- the electromechanical coupling coefficient k2 is considered, it is difficult to adopt the thickness Tb that makes the TCF almost zero.
- the electromechanical coupling coefficient k2 may be reduced, so the thickness Tb can be set so that the TCF is nearly zero.
- FIG. 13 is a diagram showing changes ⁇ f in resonance frequency with respect to time.
- the materials and dimensions of Example 1 are the materials and dimensions exemplified as a piezoelectric thin film resonator having a resonance frequency of 2.4 GHz.
- the insertion film 28 is a silicon oxide film
- the thickness Ta of the thick film portion 28a is 180 nm
- the thickness Tb of the thin film portion 28b is 73 nm.
- Comparative Example 1 is the same as Example 1 except that the thin film portion 28b is not provided.
- ⁇ f changes greatly after the power is turned on, and it takes about 500 seconds for ⁇ f to stabilize. Moreover, even after ⁇ f is stabilized, the frequency drift is large and ⁇ f is not stabilized. In Example 1, ⁇ f is very stable immediately after the power is turned on. In Comparative Example 2, the reason why ⁇ f changes greatly after power-on is considered to be that the temperature rises due to self-heating of the piezoelectric thin film resonator upon power-on. Even after the element temperature of the piezoelectric thin film resonator is stabilized, it is considered that ⁇ f is not stabilized due to small fluctuations in the environmental temperature.
- Example 1 the provision of the thin film portion 28b can reduce the TCF to almost 0, so it is considered that ⁇ f is stable. Therefore, in Example 1, frequency changes due to element temperature and environmental temperature can be suppressed, so that the amount of change in mass of substances such as specific atoms or molecules in gas or liquid can be measured more accurately.
- a slight change in resonance frequency does not pose a problem as long as the temperature change in the passband is within an allowable range.
- the thin film portion 28b is thickened to make the TCF 0 , the electromechanical coupling coefficient k2 is lowered and the achievable bandwidth is restricted, making it difficult to design a high frequency filter. Therefore, TCF may not be set to 0 in some cases.
- the detection element detects changes in the environment based on changes in the resonance frequency, even a slight change in the resonance frequency poses a problem.
- the electromechanical coupling coefficient k2 is lowered in the detection element, it does not pose a serious problem as in the case of the high frequency filter.
- Example 1 by providing the thin film portion 28b, the TCF can be brought close to 0, and the resonance frequency can be stabilized.
- the thin film portion 28b of the insertion film 28 is provided in the center of the resonance region 50 in plan view, and the thick film portion 28a of the insertion film 28 surrounds the thin film portion 28b and surrounds the resonance region 50 in plan view.
- the sensitive film 24 is provided on the upper surface of the upper electrode 16 and provided in a recess 22 (region) surrounded by a step 23 (first step) defined by a thin film portion 28b and a thick film portion 28a. Since the sensitive film 24 is provided in the concave portion 22, even if the sensitive film 24 is made thin, the planar shape of the sensitive film 24 is distorted. It is possible to suppress the formation of the spurious 56 due to becoming. Also, the sensitive film 24 can be formed relatively flat.
- the characteristics of the resonator can be stabilized. Furthermore, since the recessed portion 22 is defined by the thin film portion 28b and the thick film portion 28a, the complicated manufacturing process of forming a dam as in Patent Document 1 is not necessary, and the manufacturing process can be simplified.
- the sign of the temperature coefficient of the elastic constant of the thin film portion 28b is opposite to the sign of the temperature coefficient of the piezoelectric film 14.
- the TCF can be reduced as shown in FIG. 12 of Experiment 4. Therefore, as shown in FIG. 13 of Experiment 5, when the detection element is operated, the characteristics of the resonator can be stabilized.
- the thick film portion 28 a includes a film having a Young's modulus smaller than that of the piezoelectric film 14 .
- the Q value can be improved as shown in FIG. 11(b) of Experiment 3.
- the detection element has a low Q value due to the presence of the sensitive film 24 . Therefore, it is preferable to provide the thick film portion 28a.
- the piezoelectric film 14 is mainly composed of an aluminum nitride film
- the insertion film 28 is mainly composed of silicon oxide. Silicon oxide has a positive temperature coefficient of elastic constant and aluminum nitride has a negative temperature coefficient of elastic constant. Also, the Young's modulus of silicon oxide is smaller than that of aluminum nitride. Therefore, the insertion film 28 can reduce the TCF and improve the Q value. It should be noted that the main component allows intentional or unintentional inclusion of impurities.
- the piezoelectric film 14 is mainly composed of aluminum nitride
- the total concentration of O and Al in the piezoelectric film 14 is 50 atomic % or more or 80 atomic % or more, and both the O concentration and the Al concentration are 10 atomic % or more. atomic % or more, or 20 atomic % or more.
- the insertion film 28 is mainly composed of silicon oxide
- the total concentration of O and Si in the insertion film 28 is 50 atomic % or more or 80 atomic % or more, and both the O concentration and the Si concentration are 10 atomic % or more. atomic % or more, or 20 atomic % or more.
- the insertion film 28 may be provided between the lower electrode 12 and the piezoelectric film 14, or may be provided between the piezoelectric film 14 and the upper electrode 16. Since the insertion film 28 is provided between the lower piezoelectric film 14a and the upper piezoelectric film 14b as in the first embodiment, the TCF can be reduced even if the thicknesses Ta and Tb of the insertion film 28 are small, and the Q value can be reduced. can be increased.
- the thickness Ta of the thick film portion 28a is preferably 1.1 times or more the thickness Tb of the thin film portion 28b, more preferably 1.5 times or more, and still more preferably 2 times or more.
- the step 23 defined by the step Td between the thick film portion 28a and the thin film portion 28b can be formed on the upper electrode 16.
- the height D1 of the step 23 is preferably 1/4 or more of the thickness Ta, more preferably 1/2 or more of Ta.
- the difference between Ta and Tb is preferably 50 nm or more, more preferably 100 nm or more.
- the height D1 of the step 23 is preferably 50 nm or more, more preferably 100 nm or more.
- Ta is preferably 0.1 times or more the thickness of the piezoelectric film 14, more preferably 0.2 times or more, and even more preferably 0.3 times or more. If Ta is thick, formation of the insertion film 28 becomes difficult. Therefore, it is preferable that Ta is 5 times or less than Tb, the difference between Ta and Tb is 500 nm or less, and Ta is 0.5 times or less the thickness of the piezoelectric film 14 .
- D1 is preferably 4 times or less than Tb, and D1 is preferably 500 nm or less.
- the width of the thick film portion 28a in the direction orthogonal to the outer periphery of the resonance region 50 is 0.3 to 2.0 times the wavelength of the elastic wave (twice the total thickness of the lower electrode 12, piezoelectric film 14 and upper electrode 16). 5 times is preferred.
- the presence of the step 23 in the resonance region 50 suppresses the sensitive film 24 from flowing out of the resonance region 50, and the film thickness difference between the central portion and the outer peripheral portion of the sensitive film 24 can be reduced. . Therefore, like the resonator B of Experiment 3, it is possible to suppress the formation of the spurious 56 due to the planar shape of the sensitive film 24 being distorted.
- a problem when forming a dam using a protective film as shown in FIG. 17(b) of Patent Document 1 will be described.
- Method 1 After forming a thick protective film, the area surrounded by the dam on the upper surface of the protective film is etched.
- Method 2 forms a thin overcoat and forms an additional overcoat in the area where the dam will be formed.
- a mask layer is formed on the protective film using photolithography. Since the protective film is provided on the upper electrode, the upper surface of the protective film has large unevenness. As a result, the alignment accuracy of the pattern of the mask layer for forming the dam deteriorates.
- the mask layer when the top surface of the protective film has large unevenness, it is difficult for the mask layer to cover the unevenness of the top surface of the protective film. As a result, the mask layer becomes thin in the region where the mask layer is to be formed, and the protective film may be etched. In some cases, the mask layer is so thick that the protective film is not etched in the region where the opening of the mask layer is to be formed. Furthermore, if the mask layer does not cover the protective film cleanly, etching residue or an etchant may enter between the mask layer and the protective film during etching of the protective film.
- FIG. 14 is an enlarged cross-sectional view showing an example of the steps of the piezoelectric film, insertion film, upper electrode, and sensitive film in Example 1.
- FIG. 14 the upper surface of the lower piezoelectric film 14a is substantially flat.
- FIG. 1B due to the dome-shaped air gap 30, the upper surface of the lower piezoelectric film 14a in the resonance region 50 is dome-shaped.
- the width of the resonance region 50 is several tens of ⁇ m to several hundred ⁇ m
- the height of the air gap 30 is several ⁇ m.
- an insertion film 28 having a thick film portion 28a and a thin film portion 28b is formed on the lower piezoelectric film 14a.
- a step 26a (second step) is provided on the upper surface of the insertion film 28 so that the upper surface of the thin film portion 28b is recessed toward the substrate 10 from the upper surface of the thick film portion 28a.
- the upper surface of the thin film portion 28b becomes the concave portion 26.
- An upper piezoelectric film 14b is formed on the insertion film 18, as shown in FIG. 3(a).
- a step 27a is formed on the upper surface of the piezoelectric film 14 so that the upper surface of the piezoelectric film 14 corresponding to the thin film portion 28b is recessed toward the substrate 10 from the upper surface of the piezoelectric film 14 corresponding to the thick film portion 28a. (third step) is provided.
- a region of the upper surface of the piezoelectric film 14 surrounded by the steps 27a becomes a concave portion 27. As shown in FIG.
- An upper electrode 16 is formed on the piezoelectric film 14 as shown in FIG. 3(b). As a result, as shown in FIG. 14, the upper surface of the upper electrode 16 corresponding to the thin film portion 28b is recessed toward the substrate 10 from the upper electrode 16 corresponding to the thick film portion 28a. 1 step) is provided. A region of the upper surface of the upper electrode 16 surrounded by the steps 23 becomes a concave portion 22 .
- a sensitive film 24 is formed in the recess 22 on the upper surface of the upper electrode 16. As shown in FIG. Thereby, the planar shape of the sensitive film 24 is not distorted and spurious can be suppressed.
- the slope of the step 27a becomes gentler than the slope of the step 26a. That is, the angle ⁇ 2 of the surface of the step 27a with respect to the bottom surface of the recess 27 is smaller than the angle ⁇ 1 of the surface of the step 26a with respect to the bottom surface of the recess 26.
- the slope of the step 23 is gentler than that of the step 27a. That is, the angle ⁇ 3 of the surface of the step 23 with respect to the bottom surface of the recess 22 is smaller than the angle ⁇ 2 of the surface of the step 27a with respect to the bottom surface of the recess 27 .
- the slope of the step 23 can be made gentler than the slope of the step 26a.
- the slope of the step 23 is steep (that is, if the angle ⁇ 3 is close to 90°)
- the sensitivity near the step 23 in the concave portion 22 is reduced. Voids and the like are likely to be formed in the film 24 .
- the slope of the step 23 is steep, when the solvent containing the sensitive film 24 is applied to the concave portion 22, uneven coating occurs near the step 23, and the thickness of the sensitive film 24 tends to vary. Therefore, the sensitivity of the sensitive film 24 becomes uneven.
- the slope of the step 23 can be made gentler than the slope of the step 26a. This can suppress the formation of voids near the step 23, variations in the thickness of the sensitive film 24, and the like. Therefore, the sensitivity of the sensitive film 24 can be made uniform.
- an etchant for etching the piezoelectric film 14 is applied to the interface between the insertion film 28 and the upper piezoelectric film 14b, and the upper piezoelectric film 14b and the upper electrode 16.
- the etchant can penetrate the interface between
- the step 26a is provided on the upper surface of the insertion film 28
- the step 27a is provided on the upper surface of the upper piezoelectric film 14b
- the etchant can be prevented from entering the interface between the upper piezoelectric film 14b and the upper electrode 16.
- Table 2 summarizes film thickness and TCF in the case of copper phthalocyanine (CuPc), which is an organic low-molecular material, as the sensitive film 24 on the upper electrode 16 of the detection element.
- CuPc copper phthalocyanine
- the thickness Tb of the thin film portion 28b is preferably set so that the TCF (frequency temperature coefficient) of the resonance frequency of the detection element is -20 ppm/K or more and 20 ppm/K or less. Thereby, as shown in FIG. 13 of Experiment 5, the characteristics of the resonator can be stabilized when the detection element is operated.
- the TCF is more preferably -10 ppm/K or more and 10 ppm/K or less, and more preferably -5 ppm/K or more and 5 ppm/K or less.
- Modification 1 of Embodiment 1 Modifications 1 and 2 of Example 1 are examples in which the structure of the gap is changed.
- 15A is a cross-sectional view of a detection element according to Modification 1 of Example 1.
- FIG. 15(a) a recess is formed in the upper surface of the substrate 10.
- the lower electrode 12 is formed flat on the substrate 10 .
- a void 30 is formed in the depression of the substrate 10 .
- Air gap 30 is formed to include resonance region 50 .
- Other configurations are the same as those of the first embodiment, and description thereof is omitted.
- the void 30 may be formed to penetrate the substrate 10 .
- FIG. 15B is a cross-sectional view of a detection element according to Modification 2 of Example 1.
- FIG. 15(b) an acoustic reflection film 31 is formed under the lower electrode 12 in the resonance region 50.
- the acoustic reflection film 31 is alternately provided with films 31a with low acoustic impedance and films 31b with high acoustic impedance.
- the thickness of the films 31a and 31b is, for example, approximately ⁇ /4 ( ⁇ is the wavelength of the acoustic wave).
- the number of layers of the films 31a and 31b can be set arbitrarily.
- the acoustic reflection film 31 may be formed by stacking at least two types of layers with different acoustic properties with a gap therebetween.
- the substrate 10 may be one of at least two layers having different acoustic characteristics of the acoustic reflection film 31 .
- the acoustic reflection film 31 may have a structure in which one film having a different acoustic impedance is provided in the substrate 10 .
- Other configurations are the same as those of the first embodiment, and description thereof is omitted.
- the piezoelectric thin film resonator used for the detection element is an FBAR (Film Bulk Acoustic Resonator) in which the air gap 30 is formed between the substrate 10 and the lower electrode 12 in the resonance region 50. It's okay.
- the piezoelectric thin film resonator includes an SMR (Solidly Mounted Resonator) including an acoustic reflection film 31 that reflects an elastic wave propagating through the piezoelectric film 14 under the lower electrode 12 in the resonance region 50. ) can be used.
- the acoustic reflection layer including the resonance region 50 may include the void 30 or the acoustic reflection film 31 .
- planar shape of the resonance region 50 may be any shape such as a square shape, a polygonal shape such as a pentagonal shape, or the like.
- Example 2 is an example of a detection system including the detection elements of Example 1 and its modifications.
- FIG. 16 is a block diagram showing the configuration of the odor detection device 100 according to this embodiment.
- the odor detection device 100 includes an odor detection section 110 and a control section 120 .
- Odor detection unit 110 includes chamber 111 , detection element 112 , humidity sensor 113 , temperature sensor 114 , first pump 115 , second pump 116 and filter 117 .
- Chamber 111 accommodates sensing element 112 , humidity sensor 113 and temperature sensor 114 .
- the chamber 111 is provided with a first inlet 111a, a second inlet 111b and an outlet 111c.
- the detection element 112 is housed inside the chamber 111 and detects the odor component contained in the gas supplied inside the chamber 111 .
- the detection element 112 is a sensor capable of detecting an odor component by adsorbing the odor component, and as shown in FIGS. It has a configuration in which a sensitive film 24 is provided. When an odor component is adsorbed on the surface of the sensitive film 24, the resonance frequency fluctuates (decreases) according to the mass of the odor component, so a minute change in mass can be detected.
- the odor components detected by the detection element 112 are typically relatively heavy molecules in the air, such as polymer compounds, but are not particularly limited.
- the odor component detected by the detection element 112 is not limited to a component that can be sensed by human sense of smell, and may be a chemical species present in gas.
- the odor detection device 100 includes 16 detection elements 112 from channel 1 (ch1) to channel 16 (ch16). Each detection element 112 may have a different sensitive film 24 to adsorb different odor components. That is, a plurality of detection elements 112 may be provided, and the sensitive films 24 of at least two detection elements 112 among the plurality of detection elements 112 may be made of different materials.
- the number of detection elements 112 included in the odor detection device 100 is not particularly limited, and may be one or more.
- a humidity sensor 113 and a temperature sensor 114 are housed inside the chamber 111 and detect the humidity and temperature inside the chamber 111 .
- the types of humidity sensor 113 and temperature sensor 114 are not particularly limited.
- the first pump 115 is connected to the first inlet 111a and pumps gas into the chamber 111 through the first inlet 111a.
- the first pump 115 may be, for example, a diaphragm pump, but may also be another pump.
- the second pump 116 is connected to the second inlet 111b and pumps gas into the chamber 111 through the second inlet 111b.
- the second pump 116 can be, for example, a diaphragm pump, but can also be other pumps. Although the first pump 115 and the second pump 116 are used in FIG. 16, these pumps may be omitted.
- the filter 117 is connected to the second suction port 111b and removes odor components from the gas flowing into the chamber 111 through the second suction port 111b.
- the filter 117 has a configuration capable of removing at least the odor component that is the detection target of each detection element 112 . Moreover, it is preferable that the filter 117 can remove water molecules.
- control unit 120 is connected to the odor detection unit 110 and arithmetically processes the output of the odor detection unit 110 .
- control unit 120 includes acquisition unit 121 , calculation unit 122 , determination unit 123 and storage unit 124 .
- Acquisition unit 121 is connected to each detection element 112, humidity sensor 113, and temperature sensor 114 as shown in FIG. 16, and acquires the output of each sensor.
- the connection between the acquisition unit 121 and each sensor may be wired or wireless.
- the acquisition unit 121 supplies the acquired output of each sensor to the calculation unit 122 .
- the calculation unit 122 performs calculation processing using the output of each sensor supplied from the acquisition unit 121 and supplies the calculation result to the determination unit 123 .
- the determination unit 123 uses the calculation result supplied from the calculation unit 122 to determine the odor component.
- the determination unit 123 can determine at least one of the presence or absence of an odor component, the concentration of the odor component, the type of odor, and the intensity of the odor.
- the determination unit 123 supplies the determination result and the measurement result by the odor detection unit 110 to the storage unit 124 .
- Storage unit 124 stores the result of determination by determination unit 123 and the result of measurement by odor detection unit 110 .
- Each configuration of the control unit 120 described above is a functional configuration realized by cooperation of hardware such as a processor and memory and software, and the implementation mode is not particularly limited. That is, the control section 120 may be implemented by an information processing unit configured integrally with the odor detection section 110 or may be implemented by an information processing unit independent of the odor detection section 110 . Moreover, each functional configuration of the control unit 120 may be implemented by a plurality of information processing units connected via a network. In addition, the detection element of the modification 1 or 2 shown in FIG.15(a) and FIG.15(b) may be used for a detection element.
- a detection system using the detection element 112 may be any detection system that detects changes in the environment based on the signal output by the detection element 112 .
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Abstract
This detecting element comprises a substrate 10, a piezoelectric film 14 provided on the substrate, a lower electrode 12 and an upper electrode 16 opposing one another across at least a portion of the piezoelectric film, an insertion film 28 comprising a thin film portion 28b that is provided between the lower electrode and the upper electrode in a resonance region 50 defined by a region in which the lower electrode and the upper electrode face one another sandwiching at least a portion of the piezoelectric film, and that is provided inward of the resonance region in a plan view, and a thick film portion 28a which surrounds the thin film portion in a plan view, is provided in a peripheral edge of the resonance region, and is thicker than the thin film portion, and a sensitive film 24 provided in a region surrounded by a first step 23 which is provided on an upper surface of the upper electrode and which is defined by the thin film portion and the thick film portion, wherein a resonant frequency changes in accordance with a change in environment.
Description
本発明は、検出素子およびその製造方法並びに検出システムに関し、例えば共振器を有する検出素子およびその製造方法並びに検出システムに関する。
The present invention relates to a detection element, its manufacturing method, and a detection system, for example, a detection element having a resonator, its manufacturing method, and its detection system.
感応膜の質量の変化を検出することで、気体もしくは液体中の特定原子もしくは分子の濃度、温度、または湿度等の環境の変化を検出する環境センサが知られている。圧電薄膜共振器の上部電極上に感応膜を設け、感応膜の質量変化による共振周波数の変化に基づき環境の変化を検出する検出システムが知られている(例えば特許文献1)。圧電薄膜共振器は、圧電膜を挟み下部電極と上部電極とが対向する構造を有している。圧電膜の少なくとも一部を挟み下部電極と上部電極とが対向する領域は弾性波が共振する共振領域である。圧電薄膜共振器の圧電膜内に挿入膜を設けることが知られている(例えば特許文献2)。
Environmental sensors are known that detect changes in the environment, such as the concentration of specific atoms or molecules in a gas or liquid, temperature, or humidity, by detecting changes in the mass of a sensitive film. A detection system is known in which a sensitive film is provided on the upper electrode of a piezoelectric thin film resonator and changes in the environment are detected based on changes in resonance frequency due to changes in the mass of the sensitive film (for example, Patent Document 1). A piezoelectric thin film resonator has a structure in which a lower electrode and an upper electrode face each other with a piezoelectric film interposed therebetween. A region where the lower electrode and the upper electrode face each other with at least a portion of the piezoelectric film therebetween is a resonance region where elastic waves resonate. It is known to provide an insertion film in the piezoelectric film of a piezoelectric thin film resonator (for example, Patent Document 2).
感応膜が安定に形成されないと、共振器の特性が安定しない。特許文献1の図17(b)のように、共振領域を囲むように保護膜を用いダムを形成すると製造工程が複雑になる。さらに、検出素子を動作させたときに、共振器の特性が安定しないことがある。
If the sensitive film is not stably formed, the characteristics of the resonator will not be stable. As shown in FIG. 17B of Patent Document 1, forming a dam using a protective film so as to surround the resonance region complicates the manufacturing process. Furthermore, the characteristics of the resonator may not stabilize when the sensing element is operated.
本発明は、上記課題に鑑みなされたものであり、製造工程を簡略化しかつ共振器の特性を安定させることを目的とする。
The present invention has been made in view of the above problems, and aims to simplify the manufacturing process and stabilize the characteristics of the resonator.
本発明は、基板と、前記基板上に設けられた圧電膜と、前記圧電膜の少なくとも一部を挟んで対向した下部電極および上部電極と、前記圧電膜の少なくとも一部を挟み前記下部電極と前記上部電極とが対向する領域により画定される共振領域内の前記下部電極と前記上部電極との間に設けられ、平面視において前記共振領域より内側に設けられた薄膜部と、平面視において前記薄膜部を囲み前記共振領域の周縁に設けられ前記薄膜部より厚い厚膜部と、を備える挿入膜と、前記上部電極の上面に設けられた前記薄膜部と前記厚膜部とにより画定された第1段差で囲まれた領域に設けられた感応膜と、を備え、環境の変化により共振周波数が変化する検出素子である。
The present invention comprises a substrate, a piezoelectric film provided on the substrate, a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film therebetween, and the lower electrode with at least a portion of the piezoelectric film therebetween. a thin film portion provided between the lower electrode and the upper electrode in a resonance region defined by a region facing the upper electrode and inside the resonance region in plan view; a thick film portion that surrounds the thin film portion and is provided at the periphery of the resonance region and is thicker than the thin film portion; and a sensitive film provided in a region surrounded by the first steps, the detecting element having a resonant frequency that changes with changes in the environment.
上記構成において、前記薄膜部の弾性定数の温度係数の符号は前記圧電膜の弾性定数の温度係数の符号とは反対である構成とすることができる。
In the above configuration, the sign of the temperature coefficient of the elastic constant of the thin film portion may be opposite to the sign of the temperature coefficient of the elastic constant of the piezoelectric film.
上記構成において、前記厚膜部は、前記圧電膜のヤング率よりヤング率の小さい膜を含む構成とすることができる。
In the above configuration, the thick film portion may include a film having a Young's modulus smaller than the Young's modulus of the piezoelectric film.
上記構成において、前記圧電膜は窒化アルミニウム膜を主成分とし、前記挿入膜は酸化シリコンを主成分とする構成とすることができる。
In the above configuration, the piezoelectric film may be composed mainly of an aluminum nitride film, and the insertion film may be composed mainly of silicon oxide.
上記構成において、前記圧電膜は、前記下部電極上に設けられた下部圧電膜と、前記下部圧電膜上に設けられた上部圧電膜と、を備え、前記挿入膜は前記下部圧電膜と前記上部圧電膜との間に設けられている構成とすることができる。
In the above configuration, the piezoelectric film includes a lower piezoelectric film provided on the lower electrode and an upper piezoelectric film provided on the lower piezoelectric film, and the insertion film comprises the lower piezoelectric film and the upper piezoelectric film. It can be configured to be provided between the piezoelectric film.
上記構成において、前記厚膜部の厚さは前記薄膜部の厚さの1.5倍以上である構成とすることができる。
In the above configuration, the thickness of the thick film portion may be 1.5 times or more the thickness of the thin film portion.
上記構成において、前記検出素子の共振周波数の温度周波数係数は-20ppm/K以上かつ20ppm/K以下である構成とすることができる。
In the above configuration, the temperature frequency coefficient of the resonance frequency of the detection element may be -20 ppm/K or more and 20 ppm/K or less.
上記構成において、前記挿入膜の上面に、前記薄膜部の上面が前記厚膜部の上面より前基板側に凹むように第2段差が設けられ、前記圧電膜の上面に、前記薄膜部に対応する前記圧電膜の上面が前記厚膜部に対応する前記圧電膜の上面より前記基板側に凹むように第3段差が設けられ、前記第1段差は、前記薄膜部に対応する前記上部電極の上面が前記厚膜部に対応する前記上部電極より前記基板側に凹むように設けられている構成とすることができる。
In the above configuration, a second step is provided on the upper surface of the insertion film so that the upper surface of the thin film portion is recessed toward the front substrate from the upper surface of the thick film portion, and the upper surface of the piezoelectric film corresponds to the thin film portion. A third step is provided so that the upper surface of the piezoelectric film corresponding to the thick film portion is recessed toward the substrate side from the upper surface of the piezoelectric film corresponding to the thick film portion, and the first step is provided on the upper electrode corresponding to the thin film portion. An upper surface may be recessed toward the substrate from the upper electrode corresponding to the thick film portion.
上記構成において、前記第1段差の傾斜は前記第2段差の傾斜より緩やかである構成とすることができる。
In the above configuration, the slope of the first step may be gentler than the slope of the second step.
本発明は、上記検出素子と、前記検出素子の出力する信号に基づき、前記環境の変化を検出する検出システムである。
The present invention is a detection system that detects changes in the environment based on the detection element and the signal output from the detection element.
上記構成において、前記検出素子は複数設けられ、前記複数の検出素子のうち少なくとも2つの検出素子における前記感応膜は異なる材料から形成される構成とすることができる。
In the above configuration, a plurality of the detection elements may be provided, and the sensitive films in at least two of the plurality of detection elements may be made of different materials.
本発明は、基板上に設けられた圧電膜と、前記圧電膜の少なくとも一部を挟んで対向した下部電極および上部電極と、前記圧電膜の少なくとも一部を挟み前記下部電極と前記上部電極とが対向する領域により画定される共振領域内の前記下部電極と前記上部電極との間に設けられ、前記共振領域より内側に設けられた薄膜部と平面視において前記薄膜部を囲み前記共振領域の周縁に設けられ前記薄膜部より厚い厚膜部とを備える挿入膜と、を備える共振器を作製する工程と、
前記上部電極の上面に設けられた前記薄膜部と前記厚膜部とにより画定された段差で囲まれた領域に、環境の変化により質量が変化する感応膜を形成する工程と、を含む検出素子の製造方法である。 The present invention comprises a piezoelectric film provided on a substrate, a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film therebetween, and the lower electrode and the upper electrode with at least a portion of the piezoelectric film therebetween. is provided between the lower electrode and the upper electrode within the resonance region defined by the opposing regions, and surrounds the thin film portion and the resonance region in plan view with the thin film portion provided inside the resonance region. a step of fabricating a resonator comprising an insertion film comprising a thick film portion provided on the peripheral edge and thicker than the thin film portion;
forming a sensitive film whose mass changes according to environmental changes in a region surrounded by a step defined by the thin film portion and the thick film portion provided on the upper surface of the upper electrode. is a manufacturing method.
前記上部電極の上面に設けられた前記薄膜部と前記厚膜部とにより画定された段差で囲まれた領域に、環境の変化により質量が変化する感応膜を形成する工程と、を含む検出素子の製造方法である。 The present invention comprises a piezoelectric film provided on a substrate, a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film therebetween, and the lower electrode and the upper electrode with at least a portion of the piezoelectric film therebetween. is provided between the lower electrode and the upper electrode within the resonance region defined by the opposing regions, and surrounds the thin film portion and the resonance region in plan view with the thin film portion provided inside the resonance region. a step of fabricating a resonator comprising an insertion film comprising a thick film portion provided on the peripheral edge and thicker than the thin film portion;
forming a sensitive film whose mass changes according to environmental changes in a region surrounded by a step defined by the thin film portion and the thick film portion provided on the upper surface of the upper electrode. is a manufacturing method.
上記構成において、前記感応膜を形成する工程は、感応剤を含む溶剤を塗布する工程を含む構成とすることができる。
In the above configuration, the step of forming the sensitive film may include a step of applying a solvent containing a sensitive agent.
本発明によれば、製造工程を簡略化しかつ共振器の特性を安定させることを目的とする。
An object of the present invention is to simplify the manufacturing process and stabilize the characteristics of the resonator.
以下、図面を参照し実施例について説明する。
Examples will be described below with reference to the drawings.
検出素子112として圧電薄膜共振器を用いる例である。図1(a)は、実施例1に係る検出素子112の平面図、図1(b)は、図1(a)のA-A断面図である。基板10の上面の法線方向をZ方向、下部電極12が共振領域50から引き出される方向をX方向、平面方向のうちX方向に直行する方向をY方向とする。
This is an example using a piezoelectric thin film resonator as the detection element 112 . FIG. 1(a) is a plan view of the detection element 112 according to Example 1, and FIG. 1(b) is a cross-sectional view taken along the line AA in FIG. 1(a). The direction normal to the upper surface of the substrate 10 is defined as the Z direction, the direction in which the lower electrode 12 is pulled out from the resonance region 50 is defined as the X direction, and the planar direction perpendicular to the X direction is defined as the Y direction.
図1(a)および図1(b)に示すように、検出素子112では、基板10の平坦な上面と下部電極12との間にドーム状の膨らみを有する空隙30が形成されている。ドーム状の膨らみとは、例えば空隙30の周辺では空隙30の高さが小さく、空隙30の内部ほど空隙30の高さが大きくなるような形状の膨らみである。下部電極12上に、圧電膜14が設けられている。圧電膜14上に上部電極16が設けられている。共振領域50は圧電膜14の少なくとも一部を挟み下部電極12と上部電極16とが対向する領域により画定される。共振領域50は、楕円形状を有し、厚み縦振動モードのまたは厚みすべり振動モード等の弾性波が共振する領域である。
As shown in FIGS. 1(a) and 1(b), in the detection element 112, a gap 30 having a dome-shaped bulge is formed between the flat upper surface of the substrate 10 and the lower electrode 12. As shown in FIG. The dome-shaped bulge is, for example, a bulge having a shape in which the height of the gap 30 is small around the gap 30 and the height of the gap 30 increases toward the inside of the gap 30 . A piezoelectric film 14 is provided on the lower electrode 12 . An upper electrode 16 is provided on the piezoelectric film 14 . The resonance region 50 is defined by a region where the lower electrode 12 and the upper electrode 16 face each other with at least a portion of the piezoelectric film 14 interposed therebetween. The resonance region 50 has an elliptical shape, and is a region in which elastic waves in thickness longitudinal vibration mode or thickness shear vibration mode resonate.
圧電膜14は、下部電極12上に設けられた下部圧電膜14aと下部圧電膜14a上に設けられた上部圧電膜14bとを備えている。共振領域50内の下部圧電膜14aと上部圧電膜14bとの間に挿入膜28が設けられている。下部圧電膜14aと上部圧電膜14bの厚さはほぼ同じである。下部圧電膜14aと上部圧電膜14bの厚さは同じでなくてもよいが、同じとすることで、挿入膜28としての機能をより発揮する。
The piezoelectric film 14 includes a lower piezoelectric film 14a provided on the lower electrode 12 and an upper piezoelectric film 14b provided on the lower piezoelectric film 14a. An insertion film 28 is provided between the lower piezoelectric film 14 a and the upper piezoelectric film 14 b within the resonance region 50 . The thicknesses of the lower piezoelectric film 14a and the upper piezoelectric film 14b are substantially the same. Although the thicknesses of the lower piezoelectric film 14a and the upper piezoelectric film 14b do not have to be the same, by making them the same, the function of the insertion film 28 can be further exhibited.
挿入膜28は、薄膜部28bおよび厚膜部28aを備えている。厚膜部28aは薄膜部28bより厚い。薄膜部28bは、共振領域50の内側の領域54に設けられている。厚膜部28aは、共振領域50内の外周領域52の少なくとも一部に設けられている。内側の領域54は、共振領域50内の領域であって、平面視において共振領域50の内側に位置する領域である。外周領域52は、共振領域50内の領域であって、内側の領域54を囲み、共振領域50の外周を含み外周に沿った領域である。平面視において、厚膜部28aは、薄膜部28bの外周の少なくとも一部を囲み、共振領域50の外周を含み、共振領域50の外周に沿って設けられている。厚膜部28aの平面形状は、例えばリング状またはリングの少なくとも一部である。薄膜部28bの厚さは略均一であり、厚膜部28aの厚さは略均一である。
The insertion film 28 has a thin film portion 28b and a thick film portion 28a. The thick film portion 28a is thicker than the thin film portion 28b. The thin film portion 28 b is provided in a region 54 inside the resonance region 50 . The thick film portion 28 a is provided in at least a portion of the outer peripheral region 52 within the resonance region 50 . The inner area 54 is an area within the resonance area 50 and located inside the resonance area 50 in plan view. The outer peripheral region 52 is a region within the resonance region 50 , surrounds the inner region 54 , includes the outer periphery of the resonance region 50 and is along the outer periphery. In plan view, the thick film portion 28 a surrounds at least a portion of the outer circumference of the thin film portion 28 b , includes the outer circumference of the resonance region 50 , and is provided along the outer circumference of the resonance region 50 . The planar shape of the thick film portion 28a is, for example, a ring shape or at least part of a ring. The thickness of the thin film portion 28b is approximately uniform, and the thickness of the thick film portion 28a is approximately uniform.
挿入膜28の上面には厚膜部28aと薄膜部28bとの膜厚差に相当する凹部26が設けられる。圧電膜14の上面には、凹部26により画定される凹部27が形成される。上部電極16の上面には凹部26および27により画定される凹部22が形成される。すなわち、凹部22は、薄膜部28bと厚膜部28aとにより画定された段差23で囲まれた領域である。凹部27内に感応膜24が設けられている。段差23の高さはD1である。感応膜24の上面は略平坦である。
A concave portion 26 corresponding to the film thickness difference between the thick film portion 28a and the thin film portion 28b is provided on the upper surface of the insertion film 28. FIG. A concave portion 27 defined by a concave portion 26 is formed on the upper surface of the piezoelectric film 14 . A recess 22 defined by recesses 26 and 27 is formed in the upper surface of upper electrode 16 . That is, the concave portion 22 is a region surrounded by the steps 23 defined by the thin film portion 28b and the thick film portion 28a. A sensitive film 24 is provided in the recess 27 . The height of the step 23 is D1. The upper surface of the sensitive film 24 is substantially flat.
上部電極16と感応膜24との間に保護膜または周波数調整膜として絶縁膜が設けられていてもよい。共振領域50外における下部電極12および上部電極16上に金属層20が設けられている。金属層20は、例えばパッドまたは配線である。下部電極12には犠牲層をエッチングするための孔部35が設けられている。孔部35は空隙30につながっている。
An insulating film may be provided as a protective film or a frequency adjusting film between the upper electrode 16 and the sensitive film 24 . A metal layer 20 is provided on the lower electrode 12 and the upper electrode 16 outside the resonance region 50 . The metal layer 20 is, for example, pads or wiring. The lower electrode 12 is provided with a hole 35 for etching the sacrificial layer. The hole 35 is connected to the air gap 30 .
以下、環境の変化とは、検出素子112の周囲の気体または液体中の特定の物質の濃度、湿度、温度または光強度等の変化を指す。気体または液体中の特定の原子または分子等の物質が感応膜24に吸着すると感応膜24の質量が増加し、検出素子の共振周波数が低下する。感応膜24の周囲の湿度が高くなると、水分が感応膜24に吸着し感応膜24の質量が増加するため、検出素子112の共振周波数が低下する。温度が変化すると、感応膜24の特定の原子または分子等物質に対する吸脱着特性が変化するので、結果、感応膜24の質量が変化する。また、温度が変化すると、感応膜24と圧電薄膜共振器それぞれの温度特性に起因して、検出素子の共振周波数が変化する。紫外線等の光が感応膜24に照射されると、感応膜24の特定の原子または分子等物質に対する吸脱着特性が変化するので、結果、感応膜24の質量が変化し、検出素子の共振周波数が変化する。このように、環境の変化により、検出素子112の共振周波数が変化する。検出素子112の共振周波数の変化により、環境の変化を検出できる。
Hereinafter, environmental changes refer to changes in the concentration of a specific substance in the gas or liquid surrounding the detection element 112, humidity, temperature, light intensity, or the like. When substances such as specific atoms or molecules in gas or liquid are adsorbed on the sensitive film 24, the mass of the sensitive film 24 increases and the resonance frequency of the detection element decreases. When the humidity around the sensitive film 24 increases, water is adsorbed on the sensitive film 24 and the mass of the sensitive film 24 increases, so that the resonance frequency of the detection element 112 decreases. When the temperature changes, the adsorption/desorption characteristics of the sensitive film 24 for substances such as specific atoms or molecules change, and as a result, the mass of the sensitive film 24 changes. Further, when the temperature changes, the resonance frequency of the detection element changes due to the temperature characteristics of the sensitive film 24 and the piezoelectric thin film resonator. When the sensitive film 24 is irradiated with light such as ultraviolet rays, the adsorption/desorption characteristics of the sensitive film 24 with respect to substances such as specific atoms or molecules change, and as a result, the mass of the sensitive film 24 changes, and the resonance frequency of the detection element changes. changes. Thus, the resonance frequency of the sensing element 112 changes due to changes in the environment. A change in the environment can be detected by a change in the resonant frequency of the sensing element 112 .
基板10は、例えばシリコン基板、サファイア基板、石英基板、ガラス基板、セラミック基板またはGaAs基板である。下部電極12および上部電極16は、例えばルテニウム(Ru)、クロム(Cr)、アルミニウム(Al)、チタン(Ti)、銅(Cu)、モリブデン(Mo)、タングステン(W)、タンタル(Ta)、白金(Pt)、ロジウム(Rh)またはイリジウム(Ir)等の単層膜またはこれらの積層膜である。下部電極12は、例えば基板10側からクロム膜およびルテニウム膜であり、上部電極16は、例えば圧電膜14側からルテニウム膜およびクロム膜である。
The substrate 10 is, for example, a silicon substrate, a sapphire substrate, a quartz substrate, a glass substrate, a ceramic substrate or a GaAs substrate. The lower electrode 12 and the upper electrode 16 are made of, for example, ruthenium (Ru), chromium (Cr), aluminum (Al), titanium (Ti), copper (Cu), molybdenum (Mo), tungsten (W), tantalum (Ta), A single layer film of platinum (Pt), rhodium (Rh), iridium (Ir), or the like, or a laminated film thereof. The lower electrode 12 is, for example, a chromium film and a ruthenium film from the substrate 10 side, and the upper electrode 16 is, for example, a ruthenium film and a chromium film from the piezoelectric film 14 side.
圧電膜14は、例えば窒化アルミニウム(AlN)膜、酸化亜鉛(ZnO)膜、窒化ガリウム(GaN)膜、チタン酸ジルコン酸鉛(PZT)膜、チタン酸鉛(PbTiO3)膜、タンタル酸リチウム(LiTaO3)膜またはニオブ酸リチウム(LiNbO3)膜である。圧電膜14は、(002)方向を主軸とする窒化アルミニウム(AlN)を主成分とし、共振特性の向上または圧電性の向上のため他の元素を含んでもよい。例えば、添加元素として、スカンジウム(Sc)、2族元素もしくは12族元素と4族元素との2つの元素、または2族元素もしくは12族元素と5族元素との2つの元素を用いることにより、圧電膜14の圧電性が向上する。このため、圧電薄膜共振器の実効的電気機械結合係数を向上できる。2族元素は、例えばカルシウム(Ca)、マグネシウム(Mg)、ストロンチウム(Sr)であり、12族元素は例えば亜鉛(Zn)である。4族元素は、例えばチタン、ジルコニウム(Zr)またはハフニウム(Hf)である。5族元素は、例えばタンタル、ニオブ(Nb)またはバナジウム(V)である。さらに、圧電膜14は、窒化アルミニウムを主成分とし、ボロン(B)を含んでもよい。
The piezoelectric film 14 is made of, for example, aluminum nitride (AlN) film, zinc oxide (ZnO) film, gallium nitride (GaN) film, lead zirconate titanate (PZT) film, lead titanate (PbTiO 3 ) film, lithium tantalate ( LiTaO 3 ) film or lithium niobate (LiNbO 3 ) film. The piezoelectric film 14 is mainly composed of aluminum nitride (AlN) whose main axis is the (002) direction, and may contain other elements to improve resonance characteristics or piezoelectricity. For example, by using scandium (Sc), two elements of a group 2 element or a group 12 element and a group 4 element, or two elements of a group 2 element or a group 12 element and a group 5 element as additive elements, The piezoelectricity of the piezoelectric film 14 is improved. Therefore, the effective electromechanical coupling coefficient of the piezoelectric thin film resonator can be improved. Group 2 elements are, for example, calcium (Ca), magnesium (Mg), and strontium (Sr), and group 12 elements are, for example, zinc (Zn). Group 4 elements are, for example, titanium, zirconium (Zr) or hafnium (Hf). Group 5 elements are, for example, tantalum, niobium (Nb) or vanadium (V). Furthermore, the piezoelectric film 14 may contain aluminum nitride as a main component and may contain boron (B).
挿入膜28の薄膜部28bは、圧電膜14の弾性定数の温度係数とは逆符号の弾性定数の温度係数を有する。これにより、共振周波数等の温度係数を0に近づけることができる。薄膜部28bは、例えば酸化シリコンまたはフッ素等の不純物を含む酸化シリコン膜である。挿入膜28の厚膜部28aの少なくとも一部は、圧電膜14よりヤング率の小さい材料の膜を含み、例えば酸化シリコン膜、アルミニウム膜、チタン膜、クロム膜、ルテニウム膜またはタングステン膜を含む。金属層20は、例えば金膜、銅膜またはアルミニウム膜等の低抵抗膜である。保護膜または周波数調整膜は例えば酸化シリコン膜、窒化シリコン膜または酸化アルミニウム膜である。
The thin film portion 28b of the insertion film 28 has a temperature coefficient of elastic constant opposite in sign to the temperature coefficient of elastic constant of the piezoelectric film 14 . As a result, the temperature coefficients such as the resonance frequency can be brought close to zero. The thin film portion 28b is, for example, silicon oxide or a silicon oxide film containing impurities such as fluorine. At least part of the thick film portion 28a of the insertion film 28 includes a film of a material having a Young's modulus smaller than that of the piezoelectric film 14, such as a silicon oxide film, an aluminum film, a titanium film, a chromium film, a ruthenium film, or a tungsten film. The metal layer 20 is a low resistance film such as a gold film, copper film or aluminum film. The protective film or frequency adjustment film is, for example, a silicon oxide film, a silicon nitride film or an aluminum oxide film.
感応膜24は、例えば有機高分子膜、有機低分子膜、または無機膜である。有機高分子材料としては、例えばポリスチレン、ポリメタクリル酸メチル、6-ナイロン、セルロースアセテート、ポリ-9,9-ジオクチレフルオレン、ポリビニルアルコール、ポリビニルカルバゾール、ポリエチレンオキシド、ポリ塩化ビニル、ポリ-p-フェニレンエーテルスルホン、ポリ-1-ブテン、ポリブタジエン、ポリフェニルメチルシラン、ポリカプロラクトン、ポリビスフェノキシホスファゼン、ポリプロピレンなどの単一構造からなるホモポリマー、ホモポリマー2種以上の共重合体であるコポリマー、これらを混合したブレンドポリマーなどを用いることができる。
The sensitive film 24 is, for example, an organic polymer film, an organic low-molecular film, or an inorganic film. Examples of organic polymer materials include polystyrene, polymethyl methacrylate, 6-nylon, cellulose acetate, poly-9,9-dioctylenefluorene, polyvinyl alcohol, polyvinylcarbazole, polyethylene oxide, polyvinyl chloride, poly-p- Homopolymers having a single structure such as phenylene ether sulfone, poly-1-butene, polybutadiene, polyphenylmethylsilane, polycaprolactone, polybisphenoxyphosphazene, and polypropylene, copolymers of two or more homopolymers, and these can be used.
例えば、有機低分子材料としては、トリス(8-キノリノラト)アルミニウム(Alq3)、ナフチルジアミン(α-NPD)、BCP(2,9 - dimethyl - 4,7 - diphenyl - 1,10 - phenanthroline)、CBP(4,4' - N,N' - dicarbazole - biphenyl)、銅フタロシアニン、フラーレン、ペンタセン、アントラセン、チオフェン、Ir(ppy(2 - phenylpyridinato))3、トリアジンチオール誘導体、ジオクチルフルオレン誘導体、テトラテトラコンタン、パリレンなどを用いることができる。
For example, organic low-molecular-weight materials include tris(8-quinolinolato)aluminum (Alq3), naphthyldiamine (α-NPD), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), CBP (4,4'-N,N'-dicarbazole-biphenyl), copper phthalocyanine, fullerene, pentacene, anthracene, thiophene, Ir(ppy(2-phenylpyridinato)) 3 , triazinethiol derivative, dioctylfluorene derivative, tetratetracontane, Parylene and the like can be used.
例えば、無機材料としては、アルミナ、チタニア、五酸化バナジウム、酸化タングステン、フッ化リチウム、フッ化マグネシウム、アルミニウム、金、銀、スズ、インジウム・ティン・オキサイド(ITO)、カーボンナノチューブ、塩化ナトリウム、塩化マグネシウムなどを用いることができる。
For example, inorganic materials include alumina, titania, vanadium pentoxide, tungsten oxide, lithium fluoride, magnesium fluoride, aluminum, gold, silver, tin, indium tin oxide (ITO), carbon nanotubes, sodium chloride, chloride Magnesium or the like can be used.
2.4GHzの共振周波数を有する圧電薄膜共振器を用いた検出素子112の場合、下部電極12は、基板10側から膜厚70nmのクロム膜および膜厚が166nmのルテニウム膜である。下部圧電膜14aは膜厚が498nmの窒化アルミニウム膜であり、上部圧電膜14bは膜厚が498nmの窒化アルミニウム膜である。挿入膜28は酸化シリコン(SiO2)膜であり、薄膜部28bの膜厚は73nm、厚膜部28aの膜厚は180nmである。上部電極16は、圧電膜14側から膜厚が166nmのルテニウム膜および膜厚が55nmのクロム膜である。感応膜24は、例えば膜厚が80nmのセルロース系樹脂(セルロースアセテート)である。上部電極16と感応膜24との間に、膜厚が70nmの酸化シリコン膜が保護膜または周波数調整膜として設けられていてもよい。各層の膜厚は、所望の共振特性を得るため適宜設定することができる。
In the case of the detection element 112 using a piezoelectric thin film resonator having a resonance frequency of 2.4 GHz, the lower electrode 12 is a chromium film with a thickness of 70 nm and a ruthenium film with a thickness of 166 nm from the substrate 10 side. The lower piezoelectric film 14a is an aluminum nitride film with a thickness of 498 nm, and the upper piezoelectric film 14b is an aluminum nitride film with a thickness of 498 nm. The insertion film 28 is a silicon oxide (SiO 2 ) film, the film thickness of the thin film portion 28b is 73 nm, and the film thickness of the thick film portion 28a is 180 nm. The upper electrode 16 is a ruthenium film with a thickness of 166 nm and a chromium film with a thickness of 55 nm from the piezoelectric film 14 side. The sensitive film 24 is, for example, a cellulose resin (cellulose acetate) with a thickness of 80 nm. A silicon oxide film having a thickness of 70 nm may be provided between the upper electrode 16 and the sensitive film 24 as a protective film or a frequency adjusting film. The film thickness of each layer can be appropriately set to obtain desired resonance characteristics.
[実施例1の製造方法]
図2(a)から図4(c)は、実施例1に係る検出素子112の製造方法を示す断面図である。図2(a)に示すように,平坦な上面有する基板10上に空隙を形成するための犠牲層38を形成する。犠牲層38は、例えば酸化マグネシウム(MgO)膜、酸化亜鉛(ZnO)膜、ゲルマニウム(Ge)膜、酸化シリコン(SiO2)膜またはリンケイ酸ガラス(PSG:phosphosilicate glass)膜である。犠牲層38の厚さは、例えば10~100nmである。犠牲層38は、スパッタリング法、真空蒸着法またはCVD(Chemical Vapor Deposition)法を用い成膜される。その後、犠牲層38を、フォトリソグラフィ技術およびエッチング技術を用い所望の形状にパターニングする。犠牲層38の形状は、空隙30の平面形状に相当する形状であり、例えば共振領域50となる領域を含む。 [Manufacturing method of Example 1]
2A to 4C are cross-sectional views showing a method for manufacturing thedetection element 112 according to Example 1. FIG. As shown in FIG. 2(a), a sacrificial layer 38 is formed on the substrate 10 having a flat top surface to form a void. The sacrificial layer 38 is, for example, a magnesium oxide (MgO) film, a zinc oxide (ZnO) film, a germanium (Ge) film, a silicon oxide (SiO 2 ) film, or a phosphosilicate glass (PSG) film. The thickness of the sacrificial layer 38 is, for example, 10-100 nm. The sacrificial layer 38 is deposited using a sputtering method, a vacuum deposition method, or a CVD (Chemical Vapor Deposition) method. After that, the sacrificial layer 38 is patterned into a desired shape using photolithography technology and etching technology. The shape of the sacrificial layer 38 is a shape corresponding to the planar shape of the air gap 30 and includes, for example, a region that becomes the resonance region 50 .
図2(a)から図4(c)は、実施例1に係る検出素子112の製造方法を示す断面図である。図2(a)に示すように,平坦な上面有する基板10上に空隙を形成するための犠牲層38を形成する。犠牲層38は、例えば酸化マグネシウム(MgO)膜、酸化亜鉛(ZnO)膜、ゲルマニウム(Ge)膜、酸化シリコン(SiO2)膜またはリンケイ酸ガラス(PSG:phosphosilicate glass)膜である。犠牲層38の厚さは、例えば10~100nmである。犠牲層38は、スパッタリング法、真空蒸着法またはCVD(Chemical Vapor Deposition)法を用い成膜される。その後、犠牲層38を、フォトリソグラフィ技術およびエッチング技術を用い所望の形状にパターニングする。犠牲層38の形状は、空隙30の平面形状に相当する形状であり、例えば共振領域50となる領域を含む。 [Manufacturing method of Example 1]
2A to 4C are cross-sectional views showing a method for manufacturing the
図2(b)に示すように、犠牲層38および基板10上に下部電極12を形成する。下部電極12は、例えば、スパッタリング法、真空蒸着法またはCVD法を用い成膜される。その後、下部電極12を、フォトリソグラフィ技術およびエッチング技術を用い所望の形状にパターニングする。下部電極12は、リフトオフ法により形成してもよい。図2(c)に示すように、下部電極12および基板10上に下部圧電膜14aを、例えば、スパッタリング法、真空蒸着法またはCVD法を用い成膜する。
The lower electrode 12 is formed on the sacrificial layer 38 and the substrate 10 as shown in FIG. 2(b). The lower electrode 12 is deposited using, for example, a sputtering method, a vacuum deposition method, or a CVD method. Thereafter, the lower electrode 12 is patterned into a desired shape using photolithography technology and etching technology. The lower electrode 12 may be formed by a lift-off method. As shown in FIG. 2C, a lower piezoelectric film 14a is formed on the lower electrode 12 and the substrate 10 using, for example, sputtering, vacuum deposition, or CVD.
図2(d)に示すように、下部圧電膜14a上に挿入膜28を形成する。フォトリソグラフィ技術およびエッチング技術を用い挿入膜28を所望の形状にパターニングする。挿入膜28は、リフトオフ法により形成してもよい。挿入膜28に厚膜部28aおよび薄膜部28bを形成する方法を説明する。下部圧電膜14a上に、厚膜部28aの厚さを有する挿入膜をスパッタリング法、真空蒸着法またはCVD法を用い形成する。その後、挿入膜のうち薄膜部28bとなる領域をフォトリソグラフィ法およびエッチング法を用い薄膜化する。これにより、厚膜部28aおよび薄膜部28bが形成される。別の方法として、下部圧電膜14a上に薄膜部28bの膜厚を有する第1の挿入膜をスパッタリング法、真空蒸着法またはCVD法を用い形成する。第1の挿入膜上にリフトオフ法を用い所望のパターンを有する第2の挿入膜を形成する。第1の挿入膜と第2の挿入膜が形成された挿入膜28は厚膜部28aとなる。第1の挿入膜が形成され第2の挿入膜が形成されていない挿入膜28は薄膜部28bとなる。挿入膜28の上面には凹部26が形成される。
As shown in FIG. 2(d), an insertion film 28 is formed on the lower piezoelectric film 14a. The insertion film 28 is patterned into a desired shape using photolithography technology and etching technology. The insertion film 28 may be formed by a lift-off method. A method for forming the thick film portion 28a and the thin film portion 28b in the insertion film 28 will be described. An insertion film having the thickness of the thick film portion 28a is formed on the lower piezoelectric film 14a by sputtering, vacuum deposition, or CVD. After that, the region of the insertion film that will become the thin film portion 28b is thinned by photolithography and etching. Thereby, the thick film portion 28a and the thin film portion 28b are formed. Alternatively, a first insertion film having the thickness of the thin film portion 28b is formed on the lower piezoelectric film 14a by sputtering, vacuum deposition, or CVD. A second insertion film having a desired pattern is formed on the first insertion film using a lift-off method. The insertion film 28 formed with the first insertion film and the second insertion film becomes the thick film portion 28a. The insertion film 28 formed with the first insertion film and not formed with the second insertion film becomes the thin film portion 28b. A concave portion 26 is formed in the upper surface of the insertion film 28 .
図3(a)に示すように、下部圧電膜14aおよび挿入膜28上に上部圧電膜14bを形成する。上部圧電膜14bは、例えばスパッタリング法、真空蒸着法またはCVD法を用い成膜される。下部圧電膜14aおよび上部圧電膜14bから圧電膜14が形成される。上部圧電膜14bの上面には、挿入膜28の凹部26に対応する凹部27が形成される。
The upper piezoelectric film 14b is formed on the lower piezoelectric film 14a and the insertion film 28, as shown in FIG. 3(a). The upper piezoelectric film 14b is formed using, for example, a sputtering method, a vacuum deposition method, or a CVD method. The piezoelectric film 14 is formed from the lower piezoelectric film 14a and the upper piezoelectric film 14b. A concave portion 27 corresponding to the concave portion 26 of the insertion film 28 is formed on the upper surface of the upper piezoelectric film 14b.
図3(b)に示すように、上部圧電膜14b上に、上部電極16を形成する。上部電極16は、例えばスパッタリング法、真空蒸着法またはCVD法を用い成膜される。上部電極16を例えばフォトリソグラフィ技術およびエッチング技術を用い所望の形状にパターニングする。上部電極16は、リフトオフ法により形成してもよい。上部電極16の上面には、挿入膜28の上面の凹部26および上部圧電膜14bの上面の凹部26に対応し、段差23に囲まれた凹部22が形成される。図3(c)に示すように、圧電膜14を例えばフォトリソグラフィ技術およびエッチング技術を用い所望の形状にパターニングする。
As shown in FIG. 3(b), the upper electrode 16 is formed on the upper piezoelectric film 14b. The upper electrode 16 is formed by sputtering, vacuum deposition, or CVD, for example. The upper electrode 16 is patterned into a desired shape using, for example, photolithography technology and etching technology. The upper electrode 16 may be formed by a lift-off method. A concave portion 22 surrounded by a step 23 is formed on the upper surface of the upper electrode 16 corresponding to the concave portion 26 on the upper surface of the insertion film 28 and the concave portion 26 on the upper surface of the upper piezoelectric film 14b. As shown in FIG. 3C, the piezoelectric film 14 is patterned into a desired shape using, for example, photolithography technology and etching technology.
図4(a)に示すように、共振領域50外の下部電極12および上部電極16上に金属層20を形成する。金属層20は、例えばスパッタリング法もしくは真空蒸着法およびリフトオフ法を用い形成する。図4(b)に示すように、孔部35(図1(a)参照)を介し、エッチング液を下部電極12の下の犠牲層38に導入する。これにより、犠牲層38が除去される。犠牲層38をエッチングする媒体としては、犠牲層38以外の共振器を構成する材料をエッチングしない媒体であることが好ましい。特に、エッチング媒体は、エッチング媒体が接触する下部電極12がエッチングされない媒体であることが好ましい。下部電極12、圧電膜14および上部電極16の応力を圧縮応力となるように設定しておく。これにより、犠牲層38が除去されると、下部電極12が基板10の反対側に基板10から離れるように膨れる。これにより、下部電極12と基板10との間にドーム状の膨らみを有する空隙30が形成される。
As shown in FIG. 4( a ), a metal layer 20 is formed on the lower electrode 12 and the upper electrode 16 outside the resonance region 50 . The metal layer 20 is formed using, for example, a sputtering method, a vacuum deposition method, and a lift-off method. As shown in FIG. 4(b), an etchant is introduced into the sacrificial layer 38 under the lower electrode 12 through the hole 35 (see FIG. 1(a)). This removes the sacrificial layer 38 . A medium for etching the sacrificial layer 38 is preferably a medium that does not etch the material constituting the resonator other than the sacrificial layer 38 . In particular, the etching medium is preferably a medium in which the lower electrode 12 in contact with the etching medium is not etched. The stresses of the lower electrode 12, the piezoelectric film 14 and the upper electrode 16 are set to be compressive stress. Thereby, when the sacrificial layer 38 is removed, the lower electrode 12 bulges away from the substrate 10 on the opposite side of the substrate 10 . Thereby, a gap 30 having a dome-shaped bulge is formed between the lower electrode 12 and the substrate 10 .
図4(c)に示すように、上部電極16の上面の凹部22内に感応膜24を形成する。感応膜24は、例えば感応膜24の材料が溶解された溶剤を塗布し、その後溶剤を乾燥させることにより形成する。また、感応膜24は、スパッタリング法または真空蒸着法とリフトオフ法を用い所望のパターンに形成してもよい。これにより、実施例1に係る検出素子112が製造される。
As shown in FIG. 4(c), a sensitive film 24 is formed in the recess 22 on the upper surface of the upper electrode 16. As shown in FIG. The sensitive film 24 is formed by, for example, applying a solvent in which the material of the sensitive film 24 is dissolved, and then drying the solvent. Also, the sensitive film 24 may be formed into a desired pattern using a sputtering method or a vacuum deposition method and a lift-off method. Thus, the detection element 112 according to Example 1 is manufactured.
[実験1]
上部電極16上に感応膜24を形成することを想定し、以下の実験1を行った。5gのアセトンを溶媒にセルロース系樹脂を溶解させた溶剤を作製した。作製した溶剤をスライドガラス上にマイクロピペットを用い約2μl(マイクロリットル)塗布し、感応剤25を作製した。各サンプルの溶剤中のセルロース系樹脂の濃度は、0.1重量%、0.5重量%および1.0重量%である。 [Experiment 1]
Assuming that thesensitive film 24 is formed on the upper electrode 16, Experiment 1 below was performed. A solvent was prepared by dissolving a cellulose resin in 5 g of acetone as a solvent. About 2 μl (microliter) of the prepared solvent was applied onto a slide glass using a micropipette to prepare a sensitive agent 25 . The concentrations of cellulosic resin in the solvent for each sample are 0.1 wt%, 0.5 wt% and 1.0 wt%.
上部電極16上に感応膜24を形成することを想定し、以下の実験1を行った。5gのアセトンを溶媒にセルロース系樹脂を溶解させた溶剤を作製した。作製した溶剤をスライドガラス上にマイクロピペットを用い約2μl(マイクロリットル)塗布し、感応剤25を作製した。各サンプルの溶剤中のセルロース系樹脂の濃度は、0.1重量%、0.5重量%および1.0重量%である。 [Experiment 1]
Assuming that the
図5(a)から図5(c)は、実験1における各溶液の塗布後の感応剤を上方から見た写真の画像である。図5(a)から図5(c)に示すように、0.5重量%と1.0重量%では感応剤25の面積はあまり変わらないが、0.1重量%では平面視の感応剤25の面積が大きくなる。さらに、0.1重量%では感応剤25の平面形状が歪になる。X方向およびY方向における感応剤25の寸法をLxおよびLyとする。
FIGS. 5(a) to 5(c) are photographic images of the sensitive agent after application of each solution in Experiment 1, viewed from above. As shown in FIGS. 5(a) to 5(c), the area of the sensitive agent 25 does not change much between 0.5% by weight and 1.0% by weight, but the area of the sensitive agent 25 at 0.1% by weight does not change when viewed from above. The area of 25 is increased. Furthermore, at 0.1% by weight, the planar shape of the sensitive agent 25 becomes distorted. Let Lx and Ly be the dimensions of the sensitive agent 25 in the X and Y directions.
図6(a)から図6(c)は、実施例1における各溶剤の塗布後の感応剤の位置に対する厚さを示す図である。図6(a)から図6(c)に示すように、感応剤25の厚さは位置により異なる。厚さTmaxは感応剤25の端部における最大膜厚であり、感応剤25の中央部の厚さをTcとする。図6(a)では、Tmax=0.35μmおよびTc=0.05μmである。図6(b)では、Tmax=3.3μmおよびTc=0.56μmである。図6(c)では、Tmax=5.40μmおよびTc=1.03μmである。このように、感応剤25は、端部で厚く中央部で薄い。各サンプルについて複数個所の感応剤25の厚さを測定した。
FIGS. 6(a) to 6(c) are diagrams showing the thickness of the sensitive agent with respect to the position after application of each solvent in Example 1. FIG. As shown in FIGS. 6(a) to 6(c), the thickness of the sensitive agent 25 differs depending on the position. The thickness Tmax is the maximum film thickness at the ends of the sensitive agent 25, and the thickness of the central portion of the sensitive agent 25 is Tc. In FIG. 6(a), Tmax=0.35 μm and Tc=0.05 μm. In FIG. 6(b), Tmax=3.3 μm and Tc=0.56 μm. In FIG. 6(c), Tmax=5.40 μm and Tc=1.03 μm. Thus, the sensitizer 25 is thick at the ends and thin at the center. The thickness of the sensitive agent 25 was measured at multiple locations for each sample.
表1は、各感応剤25の寸法Lx、Ly、厚さTmaxおよびTcまとめた表である。TmaxおよびTcは複数個所の測定結果の範囲を示している。
Table 1 summarizes the dimensions Lx, Ly, thickness Tmax and Tc of each sensitizer 25 . Tmax and Tc indicate ranges of measurement results at multiple locations.
表1に示すように、感応剤25を薄く塗布しようとすると、溶液内の感応剤の濃度を低くすることになる。しかし、濃度が低いと感応剤25の平面形状が歪になる。
As shown in Table 1, when the sensitive agent 25 is applied thinly, the concentration of the sensitive agent in the solution is lowered. However, when the concentration is low, the planar shape of the sensitive agent 25 becomes distorted.
[実験2]
実施例1について、感応膜24の厚さに対する***振周波数におけるQ値を測定した。各層の材料および寸法は実施例1において共振周波数を2.4GHzとする場合に例示した材料および寸法と同じである。 [Experiment 2]
Regarding Example 1, the Q value at the anti-resonance frequency was measured with respect to the thickness of thesensitive film 24 . The materials and dimensions of each layer are the same as those exemplified in the first embodiment when the resonance frequency is 2.4 GHz.
実施例1について、感応膜24の厚さに対する***振周波数におけるQ値を測定した。各層の材料および寸法は実施例1において共振周波数を2.4GHzとする場合に例示した材料および寸法と同じである。 [Experiment 2]
Regarding Example 1, the Q value at the anti-resonance frequency was measured with respect to the thickness of the
図7は、実験2における感応膜の厚さに対するQ値を示す図である。図7に示すように、***振周波数におけるQ値Qaは、感応膜24が厚くなると小さくなる。感応膜24の厚さが156nmの圧電薄膜共振器のQaでは、感応膜24を設けない圧電薄膜共振器のQaの1/2以下となる。感応膜24の厚さが500nmの圧電薄膜共振器ではQaがほぼ0となり共振しない。
FIG. 7 is a diagram showing the Q value with respect to the thickness of the sensitive film in Experiment 2. As shown in FIG. 7, the Q factor Qa at the anti-resonance frequency becomes smaller as the sensitive film 24 becomes thicker. The Qa of the piezoelectric thin film resonator with the sensitive film 24 having a thickness of 156 nm is less than half the Qa of the piezoelectric thin film resonator without the sensitive film 24 . In the piezoelectric thin film resonator with the sensitive film 24 having a thickness of 500 nm, Qa becomes almost 0 and does not resonate.
図7のように、感応膜24の厚さは500nm以下が好ましく、200nm以下がより好ましい。しかし、感応膜24を薄く形成しようとすると、図5(a)から図6(c)および表1のように、感応膜24の平面形状が歪になる。
As shown in FIG. 7, the thickness of the sensitive film 24 is preferably 500 nm or less, more preferably 200 nm or less. However, when it is attempted to form the sensitive film 24 thin, the planar shape of the sensitive film 24 becomes distorted as shown in FIGS.
[実験3]
感応膜24の平面形状が歪になったときの影響を調べるため、上部電極16の上面に凹部22が形成されてない比較例1に係る圧電薄膜共振器を作製した。比較例1の共振領域に感応膜24を形成した。図8(a)から図8(c)は、実験3において作製した共振器A~Cの平面図である。感応膜24の領域にハッチングした。図8(a)に示すように、共振器Aでは、上部電極16上に感応膜24は設けられていない。図8(b)に示すように、共振器Bでは、上部電極16上の共振領域50内に感応膜24が設けられている。共振領域50のうち引き出し側の領域58に感応膜24が設けられておらず、感応膜24の平面形状が歪である。図8(c)に示すように、共振器Cでは、上部電極16上の共振領域50全体に感応膜24が設けられている。 [Experiment 3]
In order to examine the influence of the distortion of the planar shape of thesensitive film 24, a piezoelectric thin film resonator according to Comparative Example 1 in which the concave portion 22 was not formed on the upper surface of the upper electrode 16 was manufactured. A sensitive film 24 was formed in the resonance region of Comparative Example 1. FIG. 8A to 8C are plan views of resonators A to C fabricated in Experiment 3. FIG. The area of the sensitive film 24 is hatched. As shown in FIG. 8( a ), in the resonator A, the sensitive film 24 is not provided on the upper electrode 16 . As shown in FIG. 8B, in the resonator B, the sensitive film 24 is provided within the resonance region 50 on the upper electrode 16 . The sensitive film 24 is not provided in a region 58 on the extraction side of the resonance region 50, and the planar shape of the sensitive film 24 is distorted. As shown in FIG. 8C, in the resonator C, the sensitive film 24 is provided over the entire resonance region 50 on the upper electrode 16. As shown in FIG.
感応膜24の平面形状が歪になったときの影響を調べるため、上部電極16の上面に凹部22が形成されてない比較例1に係る圧電薄膜共振器を作製した。比較例1の共振領域に感応膜24を形成した。図8(a)から図8(c)は、実験3において作製した共振器A~Cの平面図である。感応膜24の領域にハッチングした。図8(a)に示すように、共振器Aでは、上部電極16上に感応膜24は設けられていない。図8(b)に示すように、共振器Bでは、上部電極16上の共振領域50内に感応膜24が設けられている。共振領域50のうち引き出し側の領域58に感応膜24が設けられておらず、感応膜24の平面形状が歪である。図8(c)に示すように、共振器Cでは、上部電極16上の共振領域50全体に感応膜24が設けられている。 [Experiment 3]
In order to examine the influence of the distortion of the planar shape of the
図9(a)および図9(b)は、実験3における共振器A~Cの周波数に対するインピーダンスの大きさ|Z|を示す図である。図9(b)は、図9(a)の拡大図である。図9(a)および図9(b)に示すように、共振器Aに比べ、共振器BおよびCでは、***振周波数faおよび共振周波数frのピークが鈍っており、Q値が低くなっている。また、***振周波数faと共振周波数frの差が小さくなっており、電気機械結合係数k2が小さくなっている。このように、感応膜24を設けるとQ値および電気機械結合係数k2が低下する。共振器Bでは、faとfrとの間にスプリアス56が観測される。一方、共振器Cでは、スプリアス56は観測されない。共振器Bでは、感応膜24の平面形状が歪なためスプリアスが生じると考えられる。スプリアス56が生じると、検出素子の共振周波数frまたは***振周波数faの変動を測定するときにスプリアス56をfrまたはfaと誤認識することがある。実施例1では、上部電極16の上面の凹部22内に感応膜24を設けるため、感応膜24の平面形状が歪になることを抑制できる。これにより、スプリアス56を抑制できる。
FIGS. 9(a) and 9(b) are diagrams showing impedance magnitudes |Z| with respect to frequencies of resonators A to C in Experiment 3. FIG. FIG. 9(b) is an enlarged view of FIG. 9(a). As shown in FIGS. 9A and 9B, in resonators B and C, compared to resonator A, the peaks of the antiresonance frequency fa and the resonance frequency fr are duller, and the Q values are lower. there is Also, the difference between the anti - resonance frequency fa and the resonance frequency fr is small, and the electromechanical coupling coefficient k2 is small. As described above, the provision of the sensitive film 24 reduces the Q value and the electromechanical coupling coefficient k2 . In resonator B, spurious 56 is observed between fa and fr. On the other hand, in resonator C, spurious 56 is not observed. In the resonator B, it is considered that the spurious is generated because the plane shape of the sensitive film 24 is distorted. When the spurious 56 occurs, the spurious 56 may be erroneously recognized as fr or fa when measuring fluctuations in the resonance frequency fr or anti-resonance frequency fa of the detection element. In Example 1, since the sensitive film 24 is provided in the concave portion 22 on the upper surface of the upper electrode 16, it is possible to prevent the planar shape of the sensitive film 24 from becoming distorted. Thereby, the spurious 56 can be suppressed.
[実験4]
実施例1について、挿入膜28の厚さを変えた共振器を作製した。図10は、実験4における挿入膜を示す断面図である。図10に示すように、挿入膜28の厚膜部28aの厚さをTa、薄膜部28bの厚さをTbとした。厚さTd=Ta-Tbを107nmに固定した。その他の各層の材料および寸法は、共振周波数が2.4GHzの圧電薄膜共振器として例示した材料および寸法である。 [Experiment 4]
Similar to Example 1, resonators were fabricated by changing the thickness of theinsertion film 28 . 10 is a cross-sectional view showing an insertion membrane in Experiment 4. FIG. As shown in FIG. 10, the thickness of the thick film portion 28a of the insertion film 28 is Ta, and the thickness of the thin film portion 28b is Tb. The thickness Td=Ta-Tb was fixed at 107 nm. The materials and dimensions of other layers are the materials and dimensions exemplified for the piezoelectric thin film resonator with a resonance frequency of 2.4 GHz.
実施例1について、挿入膜28の厚さを変えた共振器を作製した。図10は、実験4における挿入膜を示す断面図である。図10に示すように、挿入膜28の厚膜部28aの厚さをTa、薄膜部28bの厚さをTbとした。厚さTd=Ta-Tbを107nmに固定した。その他の各層の材料および寸法は、共振周波数が2.4GHzの圧電薄膜共振器として例示した材料および寸法である。 [Experiment 4]
Similar to Example 1, resonators were fabricated by changing the thickness of the
図11(a)および図11(b)は、実験4における厚膜部28aの厚さTaに対するそれぞれk2およびQaを示す図である。図11(a)に示すように、厚膜部28aの厚さTaが厚くなると電気機械結合係数k2が小さくなる。図11(b)に示すように、厚さTaが厚くなると***振周波数のQ値Qaが高くなる。このように、厚膜部28aの厚さTaを厚くすると、弾性波が共振領域50から外に漏洩することを抑制できQ値を向上できる。しかし、電気機械結合係数k2が小さくなってしまう。電気機械結合係数k2が小さくなると共振周波数frと***振周波数faとの差が小さくなる。高周波フィルタでは、共振周波数frと***振周波数faとの差が小さいと、実現可能な帯域幅が制限されてしまうために高周波フィルタの設計が難しくなる。このため、特許文献2のような高周波フィルタには電気機械結合係数k2の小さい圧電薄膜共振器を用いることができない。検出素子では、Q値が高ければk2が低くてもよい。このため、厚さTaを厚くできる。
11(a) and 11( b ) are diagrams showing k2 and Qa, respectively, with respect to the thickness Ta of the thick film portion 28a in Experiment 4. FIG. As shown in FIG . 11A, as the thickness Ta of the thick film portion 28a increases, the electromechanical coupling coefficient k2 decreases. As shown in FIG. 11B, as the thickness Ta increases, the Q factor Qa of the anti-resonance frequency increases. As described above, when the thickness Ta of the thick film portion 28a is increased, it is possible to suppress leakage of elastic waves from the resonance region 50 to the outside, thereby improving the Q value. However, the electromechanical coupling coefficient k2 becomes small. As the electromechanical coupling coefficient k2 becomes smaller, the difference between the resonance frequency fr and the anti - resonance frequency fa becomes smaller. In a high-frequency filter, if the difference between the resonance frequency fr and the anti-resonance frequency fa is small, the achievable bandwidth is limited, making it difficult to design the high-frequency filter. For this reason, a piezoelectric thin film resonator having a small electromechanical coupling coefficient k2 cannot be used for a high frequency filter such as that disclosed in Patent Document 2 . A detector element may have a low k2 if the Q factor is high . Therefore, the thickness Ta can be increased.
図12は、実験4における薄膜部の厚さTbに対するTCFを示す図である。温度周波数係数(TCF:Temperature Coefficients of Frequency)は、共振周波数の温度係数である。圧電膜14の弾性定数の温度係数は負であり薄膜部28bの弾性定数の温度係数は正である。このため、薄膜部28bを設けないと、TCFは負である。薄膜部28bの厚さTbを大きくすると、TCFは正の方向に変化する。厚さTbを70nm程度とすることで、TCFをほぼ0にできる。厚さTbを厚くすると電気機械結合係数k2が低下する。高周波フィルタでは、電気機械結合係数k2を考慮するため、TCFがほぼ0になる厚さTbを採用しにくい。検出素子では、電気機械結合係数k2が低下してもよいので、厚さTbをTCFがほぼ0になるように設定できる。
12 is a diagram showing the TCF with respect to the thickness Tb of the thin film portion in Experiment 4. FIG. A temperature coefficient of frequency (TCF) is the temperature coefficient of the resonant frequency. The temperature coefficient of the elastic constant of the piezoelectric film 14 is negative, and the temperature coefficient of the elastic constant of the thin film portion 28b is positive. Therefore, TCF is negative if the thin film portion 28b is not provided. When the thickness Tb of the thin film portion 28b is increased, the TCF changes in the positive direction. By setting the thickness Tb to about 70 nm, the TCF can be made almost zero. Increasing the thickness Tb reduces the electromechanical coupling coefficient k2 . In the high - frequency filter, since the electromechanical coupling coefficient k2 is considered, it is difficult to adopt the thickness Tb that makes the TCF almost zero. In the sensing element, the electromechanical coupling coefficient k2 may be reduced, so the thickness Tb can be set so that the TCF is nearly zero.
[実験5]
図13は、時間に対する共振周波数の変化Δfを示す図である。実施例1と比較例2について、検出素子に電源を投入してからの共振周波数の変化Δfを測定した。実施例1の材料および寸法は、共振周波数が2.4GHzの圧電薄膜共振器として例示した材料および寸法である。挿入膜28は酸化シリコン膜であり、厚膜部28aの厚さTaは180nmであり、薄膜部28bの厚さTbは73nmである。比較例1では、薄膜部28bが設けられていない以外は実施例1と同じである。 [Experiment 5]
FIG. 13 is a diagram showing changes Δf in resonance frequency with respect to time. For Example 1 and Comparative Example 2, the change Δf in the resonance frequency after the detection element was powered on was measured. The materials and dimensions of Example 1 are the materials and dimensions exemplified as a piezoelectric thin film resonator having a resonance frequency of 2.4 GHz. Theinsertion film 28 is a silicon oxide film, the thickness Ta of the thick film portion 28a is 180 nm, and the thickness Tb of the thin film portion 28b is 73 nm. Comparative Example 1 is the same as Example 1 except that the thin film portion 28b is not provided.
図13は、時間に対する共振周波数の変化Δfを示す図である。実施例1と比較例2について、検出素子に電源を投入してからの共振周波数の変化Δfを測定した。実施例1の材料および寸法は、共振周波数が2.4GHzの圧電薄膜共振器として例示した材料および寸法である。挿入膜28は酸化シリコン膜であり、厚膜部28aの厚さTaは180nmであり、薄膜部28bの厚さTbは73nmである。比較例1では、薄膜部28bが設けられていない以外は実施例1と同じである。 [Experiment 5]
FIG. 13 is a diagram showing changes Δf in resonance frequency with respect to time. For Example 1 and Comparative Example 2, the change Δf in the resonance frequency after the detection element was powered on was measured. The materials and dimensions of Example 1 are the materials and dimensions exemplified as a piezoelectric thin film resonator having a resonance frequency of 2.4 GHz. The
図13に示すように、比較例2では、電源投入後Δfが大きく変化し、Δfが安定するまでに約500秒を要する。また、Δfが安定した後も周波数ドリフトが大きく、Δfが安定しない。実施例1では、電源投入の直後からΔfが非常に安定している。比較例2において、電源投入した後からΔfが大きく変化するのは、電源投入により圧電薄膜共振器の自己発熱により温度が高くなるためと考えられる。圧電薄膜共振器の素子温度が安定した後も環境温度の小さな揺らぎによりΔfが安定しないと考えられる。一方、実施例1では、薄膜部28bを設けることで、TCFをほぼ0にできるため、Δfが安定しいていると考えられる。よって、実施例1では、素子温度や環境温度による周波数変化を抑制できるため、気体または液体中の特定の原子または分子等の物質の質量変化量をより正確に測定できる。
As shown in FIG. 13, in Comparative Example 2, Δf changes greatly after the power is turned on, and it takes about 500 seconds for Δf to stabilize. Moreover, even after Δf is stabilized, the frequency drift is large and Δf is not stabilized. In Example 1, Δf is very stable immediately after the power is turned on. In Comparative Example 2, the reason why Δf changes greatly after power-on is considered to be that the temperature rises due to self-heating of the piezoelectric thin film resonator upon power-on. Even after the element temperature of the piezoelectric thin film resonator is stabilized, it is considered that Δf is not stabilized due to small fluctuations in the environmental temperature. On the other hand, in Example 1, the provision of the thin film portion 28b can reduce the TCF to almost 0, so it is considered that Δf is stable. Therefore, in Example 1, frequency changes due to element temperature and environmental temperature can be suppressed, so that the amount of change in mass of substances such as specific atoms or molecules in gas or liquid can be measured more accurately.
高周波フィルタでは、通過帯域の温度変化が許容できる範囲であれば共振周波数がわずかに変化しても問題とならない。また、TCFを0にするため薄膜部28bを厚くすると電気機械結合係数k2が低下し、実現可能な帯域幅が制限されてしまうために高周波フィルタの設計が難しくなる。そこで、TCFを0にはしない場合もある。一方、検出素子では共振周波数の変化に基づき環境の変化を検出するため、共振周波数のわずかな変化も問題となる。また、検出素子では電気機械結合係数k2が低下しても高周波フィルタほど大きな問題とならない。実施例1では、薄膜部28bを設けることで、TCFを0に近づけることができ、共振周波数を安定にすることができる。
In a high-frequency filter, a slight change in resonance frequency does not pose a problem as long as the temperature change in the passband is within an allowable range. Further, if the thin film portion 28b is thickened to make the TCF 0 , the electromechanical coupling coefficient k2 is lowered and the achievable bandwidth is restricted, making it difficult to design a high frequency filter. Therefore, TCF may not be set to 0 in some cases. On the other hand, since the detection element detects changes in the environment based on changes in the resonance frequency, even a slight change in the resonance frequency poses a problem. In addition, even if the electromechanical coupling coefficient k2 is lowered in the detection element, it does not pose a serious problem as in the case of the high frequency filter. In Example 1, by providing the thin film portion 28b, the TCF can be brought close to 0, and the resonance frequency can be stabilized.
実施例1によれば、平面視において共振領域50の中央に挿入膜28の薄膜部28bが設けられ、平面視において薄膜部28bを囲み共振領域50の周縁に挿入膜28の厚膜部28aが設けられている。感応膜24は、上部電極16の上面に設けられ薄膜部28bと厚膜部28aとにより画定された段差23(第1段差)で囲まれた凹部22(領域)に設けられている。感応膜24が、凹部22内に設けられるため、感応膜24を薄くしても、感応膜24の平面形状が歪になり、実験3の共振器Bのような感応膜24の平面形状が歪になることによるスプリアス56が形成されることを抑制できる。また、感応膜24を比較的平坦に形成できる。これにより、共振器の特性を安定にすることができる。さらに、凹部22が薄膜部28bと厚膜部28aとにより画定されるため、特許文献1のようにダムを形成する複雑な製造工程が不要となり、製造工程を簡略化できる。
According to Example 1, the thin film portion 28b of the insertion film 28 is provided in the center of the resonance region 50 in plan view, and the thick film portion 28a of the insertion film 28 surrounds the thin film portion 28b and surrounds the resonance region 50 in plan view. is provided. The sensitive film 24 is provided on the upper surface of the upper electrode 16 and provided in a recess 22 (region) surrounded by a step 23 (first step) defined by a thin film portion 28b and a thick film portion 28a. Since the sensitive film 24 is provided in the concave portion 22, even if the sensitive film 24 is made thin, the planar shape of the sensitive film 24 is distorted. It is possible to suppress the formation of the spurious 56 due to becoming. Also, the sensitive film 24 can be formed relatively flat. Thereby, the characteristics of the resonator can be stabilized. Furthermore, since the recessed portion 22 is defined by the thin film portion 28b and the thick film portion 28a, the complicated manufacturing process of forming a dam as in Patent Document 1 is not necessary, and the manufacturing process can be simplified.
薄膜部28bの弾性定数の温度係数の符号は圧電膜14の温度係数の符号とは逆である。これにより、実験4の図12のように、TCFを小さくできる。よって、実験5の図13のように、検出素子を動作させたときに、共振器の特性を安定にすることができる。
The sign of the temperature coefficient of the elastic constant of the thin film portion 28b is opposite to the sign of the temperature coefficient of the piezoelectric film 14. As a result, the TCF can be reduced as shown in FIG. 12 of Experiment 4. Therefore, as shown in FIG. 13 of Experiment 5, when the detection element is operated, the characteristics of the resonator can be stabilized.
厚膜部28aは、圧電膜14のヤング率よりヤング率の小さい膜を含む。これにより、実験3の図11(b)のように、Q値を向上できる。実験2の図7のように、検出素子では、感応膜24を設けるためQ値が低くなる。よって、厚膜部28aを設けることが好ましい。
The thick film portion 28 a includes a film having a Young's modulus smaller than that of the piezoelectric film 14 . As a result, the Q value can be improved as shown in FIG. 11(b) of Experiment 3. As shown in FIG. 7 of Experiment 2, the detection element has a low Q value due to the presence of the sensitive film 24 . Therefore, it is preferable to provide the thick film portion 28a.
圧電膜14は窒化アルミニウム膜を主成分とし、挿入膜28は酸化シリコンを主成分とする。酸化シリコンの弾性定数の温度係数は正であり窒化アルミニウムの弾性定数の温度係数は負である。また、酸化シリコンのヤング率は窒化アルミニウムのヤング率より小さい。よって、挿入膜28によりTCFを小さくしかつQ値を向上できる。なお、主成分とは、意図的または意図せず不純物が含まれることを許容する。圧電膜14が窒化アルミニウムを主成分とするとは、例えば圧電膜14内のOとAlの濃度の合計が50原子%以上または80原子%以上であり、Oの濃度とAlの濃度がいずれも10原子%以上または20原子%以上である。挿入膜28が酸化シリコンを主成分とするとは、例えば挿入膜28内のOとSiの濃度の合計が50原子%以上または80原子%以上であり、Oの濃度とSiの濃度がいずれも10原子%以上または20原子%以上である。
The piezoelectric film 14 is mainly composed of an aluminum nitride film, and the insertion film 28 is mainly composed of silicon oxide. Silicon oxide has a positive temperature coefficient of elastic constant and aluminum nitride has a negative temperature coefficient of elastic constant. Also, the Young's modulus of silicon oxide is smaller than that of aluminum nitride. Therefore, the insertion film 28 can reduce the TCF and improve the Q value. It should be noted that the main component allows intentional or unintentional inclusion of impurities. When the piezoelectric film 14 is mainly composed of aluminum nitride, for example, the total concentration of O and Al in the piezoelectric film 14 is 50 atomic % or more or 80 atomic % or more, and both the O concentration and the Al concentration are 10 atomic % or more. atomic % or more, or 20 atomic % or more. When the insertion film 28 is mainly composed of silicon oxide, for example, the total concentration of O and Si in the insertion film 28 is 50 atomic % or more or 80 atomic % or more, and both the O concentration and the Si concentration are 10 atomic % or more. atomic % or more, or 20 atomic % or more.
挿入膜28は下部電極12と圧電膜14との間に設けられていてもよいし、圧電膜14と上部電極16との間に設けられていてもよい。実施例1のように、挿入膜28が下部圧電膜14aと上部圧電膜14bの間に設けられていることにより、挿入膜28の厚さTaおよびTbが薄くてもTCFを小さくできかつQ値を大きくできる。
The insertion film 28 may be provided between the lower electrode 12 and the piezoelectric film 14, or may be provided between the piezoelectric film 14 and the upper electrode 16. Since the insertion film 28 is provided between the lower piezoelectric film 14a and the upper piezoelectric film 14b as in the first embodiment, the TCF can be reduced even if the thicknesses Ta and Tb of the insertion film 28 are small, and the Q value can be reduced. can be increased.
厚膜部28aの厚さTaは薄膜部28bの厚さTbの1.1倍以上が好ましく、1.5倍以上がより好ましく、2倍以上がさらに好ましい。これにより、上部電極16上に、厚膜部28aと薄膜部28bとの段差であるTdにより画定される段差23を形成することができる。段差23の高さD1は厚さTaの1/4以上が好ましく、Taの1/2倍以上がより好ましい。TaとTbの差は50nm以上が好ましく、100nm以上がより好ましい。段差23の高さD1は50nm以上が好ましく、100nm以上がより好ましい。Taは圧電膜14の厚さの0.1倍以上が好ましく、0.2倍以上がより好ましく、0.3倍以上がさらに好ましい。Taが厚いと挿入膜28の形成が難しくなる。よって、TaはTbの5倍以下、TaとTbとの差は500nm以下、Taは圧電膜14の厚さの0.5倍以下が好ましい。D1はTbの4倍以下、D1は500nm以下が好ましい。厚膜部28aの共振領域50の外周に直交方向の幅は、弾性波の波長(下部電極12、圧電膜14および上部電極16の合計の厚さの2倍)の0.3倍~2.5倍が好ましい。
The thickness Ta of the thick film portion 28a is preferably 1.1 times or more the thickness Tb of the thin film portion 28b, more preferably 1.5 times or more, and still more preferably 2 times or more. As a result, the step 23 defined by the step Td between the thick film portion 28a and the thin film portion 28b can be formed on the upper electrode 16. FIG. The height D1 of the step 23 is preferably 1/4 or more of the thickness Ta, more preferably 1/2 or more of Ta. The difference between Ta and Tb is preferably 50 nm or more, more preferably 100 nm or more. The height D1 of the step 23 is preferably 50 nm or more, more preferably 100 nm or more. Ta is preferably 0.1 times or more the thickness of the piezoelectric film 14, more preferably 0.2 times or more, and even more preferably 0.3 times or more. If Ta is thick, formation of the insertion film 28 becomes difficult. Therefore, it is preferable that Ta is 5 times or less than Tb, the difference between Ta and Tb is 500 nm or less, and Ta is 0.5 times or less the thickness of the piezoelectric film 14 . D1 is preferably 4 times or less than Tb, and D1 is preferably 500 nm or less. The width of the thick film portion 28a in the direction orthogonal to the outer periphery of the resonance region 50 is 0.3 to 2.0 times the wavelength of the elastic wave (twice the total thickness of the lower electrode 12, piezoelectric film 14 and upper electrode 16). 5 times is preferred.
高周波フィルタでは、厚さTaを大きくすると電気機械結合係数k2が低下するため、厚さTaを大きくできない。厚さTaが小さいと、特許文献2の図面のように上部電極上に段差が形成されない。一方、検出素子では、電気機械結合係数k2が低下しても高周波フィルタほど大きな問題とならないため、厚さTaを大きくできる。これにより、上部電極16上に段差23を形成することができる。よって、共振領域50内に形成された凹部22に位置ズレすることなく、感応膜24を塗布することができる。さらに、共振領域50内に段差23が存在することにより、感応膜24が共振領域50外に流動することを抑制し、かつ、感応膜24の中央部と外周部との膜厚差が小さくできる。よって、実験3の共振器Bのように、感応膜24の平面形状が歪になることによるスプリアス56が形成されることを抑制できる。
In the high - frequency filter, increasing the thickness Ta reduces the electromechanical coupling coefficient k2, so the thickness Ta cannot be increased. When the thickness Ta is small, a step is not formed on the upper electrode as shown in the drawings of Patent Document 2. FIG. On the other hand, in the detection element, even if the electromechanical coupling coefficient k2 decreases, the problem is not as serious as in the case of the high frequency filter, so the thickness Ta can be increased. Thereby, a step 23 can be formed on the upper electrode 16 . Therefore, the sensitive film 24 can be applied without being displaced in the concave portion 22 formed in the resonance region 50 . Furthermore, the presence of the step 23 in the resonance region 50 suppresses the sensitive film 24 from flowing out of the resonance region 50, and the film thickness difference between the central portion and the outer peripheral portion of the sensitive film 24 can be reduced. . Therefore, like the resonator B of Experiment 3, it is possible to suppress the formation of the spurious 56 due to the planar shape of the sensitive film 24 being distorted.
特許文献1の図17(b)のように、保護膜を用いダムを形成する場合の問題について説明する。保護膜を用いダムを形成する方法には2つの方向がある。方法1では、厚い保護膜を形成した後、保護膜の上面のダムに囲まれる領域をエッチングする。方法2では、薄い保護膜を形成し、ダムを形成する領域に追加の保護膜を形成する。方法1および2のいずれにおいても、保護膜上にフォトリソグラフィ法を用いマスク層を形成することになる。保護膜は上部電極上に設けられているため、保護膜の上面の凸凹が大きい。このため、ダムを形成するためのマスク層のパターンの位置合わせ精度が悪くなる。また、保護膜の上面の凸凹が大きい場合、マスク層が保護膜の上面の凸凹をきれいに覆うことが難しい。このため、マスク層を形成すべき領域においてマスク層が薄くなり保護膜がエッチングされてしまうことがある。マスク層の開口を形成すべき領域においてマスク層が厚くなり保護膜がエッチングされない場合もある。さらに、マスク層が保護膜をきれいに覆っていない場合、保護膜のエッチングのときに、エッチング残渣、または、エッチング液のマスク層と保護膜との間への侵入が生じることがある。
A problem when forming a dam using a protective film as shown in FIG. 17(b) of Patent Document 1 will be described. There are two ways to form a dam using a protective film. In method 1, after forming a thick protective film, the area surrounded by the dam on the upper surface of the protective film is etched. Method 2 forms a thin overcoat and forms an additional overcoat in the area where the dam will be formed. In both methods 1 and 2, a mask layer is formed on the protective film using photolithography. Since the protective film is provided on the upper electrode, the upper surface of the protective film has large unevenness. As a result, the alignment accuracy of the pattern of the mask layer for forming the dam deteriorates. In addition, when the top surface of the protective film has large unevenness, it is difficult for the mask layer to cover the unevenness of the top surface of the protective film. As a result, the mask layer becomes thin in the region where the mask layer is to be formed, and the protective film may be etched. In some cases, the mask layer is so thick that the protective film is not etched in the region where the opening of the mask layer is to be formed. Furthermore, if the mask layer does not cover the protective film cleanly, etching residue or an etchant may enter between the mask layer and the protective film during etching of the protective film.
図14は、実施例1における圧電膜、挿入膜、上部電極および感応膜の段差の一例を示す拡大断面図である。図14に示すように、下部圧電膜14aの上面は略平坦である。なお、図1(b)のように、ドーム状の空隙30のため、共振領域50内の下部圧電膜14aの上面はドーム状である。しかし、共振領域50の幅は数10μm~数100μmであるの対し、空隙30の高さは数μmであるため、共振領域50内の下部圧電膜14aの上面はほぼ平坦である。
FIG. 14 is an enlarged cross-sectional view showing an example of the steps of the piezoelectric film, insertion film, upper electrode, and sensitive film in Example 1. FIG. As shown in FIG. 14, the upper surface of the lower piezoelectric film 14a is substantially flat. As shown in FIG. 1B, due to the dome-shaped air gap 30, the upper surface of the lower piezoelectric film 14a in the resonance region 50 is dome-shaped. However, while the width of the resonance region 50 is several tens of μm to several hundred μm, the height of the air gap 30 is several μm.
図2(d)のように、下部圧電膜14a上に厚膜部28aと薄膜部28bを有する挿入膜28を形成する。これにより、図14のように、挿入膜28の上面に、薄膜部28bの上面が厚膜部28aの上面より基板10側に凹むように段差26a(第2段差)が設けられる。薄膜部28bの上面は凹部26になる。
As shown in FIG. 2(d), an insertion film 28 having a thick film portion 28a and a thin film portion 28b is formed on the lower piezoelectric film 14a. As a result, as shown in FIG. 14, a step 26a (second step) is provided on the upper surface of the insertion film 28 so that the upper surface of the thin film portion 28b is recessed toward the substrate 10 from the upper surface of the thick film portion 28a. The upper surface of the thin film portion 28b becomes the concave portion 26. As shown in FIG.
図3(a)のように、挿入膜18上に上部圧電膜14bを形成する。これにより、図14のように、圧電膜14の上面に、薄膜部28bに対応する圧電膜14の上面が厚膜部28aに対応する圧電膜14の上面より基板10側に凹むように段差27a(第3段差)が設けられる。圧電膜14の上面のうち段差27aで囲まれた領域は凹部27になる。
An upper piezoelectric film 14b is formed on the insertion film 18, as shown in FIG. 3(a). As a result, as shown in FIG. 14, a step 27a is formed on the upper surface of the piezoelectric film 14 so that the upper surface of the piezoelectric film 14 corresponding to the thin film portion 28b is recessed toward the substrate 10 from the upper surface of the piezoelectric film 14 corresponding to the thick film portion 28a. (third step) is provided. A region of the upper surface of the piezoelectric film 14 surrounded by the steps 27a becomes a concave portion 27. As shown in FIG.
図3(b)のように、圧電膜14上に上部電極16を形成する。これにより、図14のように、上部電極16の上面に、薄膜部28bに対応する上部電極16の上面が厚膜部28aに対応する上部電極16より基板10側に凹むように段差23(第1段差)が設けられる。上部電極16の上面のうち段差23で囲まれた領域は凹部22になる。
An upper electrode 16 is formed on the piezoelectric film 14 as shown in FIG. 3(b). As a result, as shown in FIG. 14, the upper surface of the upper electrode 16 corresponding to the thin film portion 28b is recessed toward the substrate 10 from the upper electrode 16 corresponding to the thick film portion 28a. 1 step) is provided. A region of the upper surface of the upper electrode 16 surrounded by the steps 23 becomes a concave portion 22 .
図4(c)および図14のように、上部電極16の上面の凹部22内に感応膜24を形成する。これにより、感応膜24の平面形状に歪みが形成されずスプリアスが抑制できる。
As shown in FIGS. 4(c) and 14, a sensitive film 24 is formed in the recess 22 on the upper surface of the upper electrode 16. As shown in FIG. Thereby, the planar shape of the sensitive film 24 is not distorted and spurious can be suppressed.
段差26a上に段差27aを形成すると、段差27aの傾斜は段差26aの傾斜より緩やかになる。すなわち、段差27aの面の凹部27の底面に対する角度θ2は、段差26aの面の凹部26の底面に対する角度θ1より小さくなる。段差27a上に段差23を形成すると、段差23の傾斜は段差27aの傾斜より緩やかになる。すなわち、段差23の面の凹部22の底面に対する角度θ3は、段差27aの面の凹部27の底面に対する角度θ2より小さくなる。このように、段差23の傾斜を段差26aの傾斜より緩やかにできる。
When the step 27a is formed on the step 26a, the slope of the step 27a becomes gentler than the slope of the step 26a. That is, the angle θ2 of the surface of the step 27a with respect to the bottom surface of the recess 27 is smaller than the angle θ1 of the surface of the step 26a with respect to the bottom surface of the recess 26. When the step 23 is formed on the step 27a, the slope of the step 23 is gentler than that of the step 27a. That is, the angle θ3 of the surface of the step 23 with respect to the bottom surface of the recess 22 is smaller than the angle θ2 of the surface of the step 27a with respect to the bottom surface of the recess 27 . Thus, the slope of the step 23 can be made gentler than the slope of the step 26a.
段差23の傾斜が急峻な場合(すなわち角度θ3が90°に近い場合)、凹部22に感応膜24を含む溶剤を塗布または感応膜24をスパッタリングするときに、凹部22内の段差23付近の感応膜24にボイド等が形成されやすい。また、段差23の傾斜が急峻であるときには、感応膜24を含む溶剤を凹部22に塗布するときに、段差23付近に塗布むらが発生し、感応膜24の厚さがばらつきやすくなる。このため、感応膜24の感度が不均一になる。実施例1では、段差23の傾斜を段差26aの傾斜より緩やかにできる。これにより、段差23付近のボイドの形成、感応膜24の厚さのばらつき等を抑制できる。よって、感応膜24の感度を均一にできる。
If the slope of the step 23 is steep (that is, if the angle θ3 is close to 90°), when the solvent containing the sensitive film 24 is applied to the concave portion 22 or the sensitive film 24 is sputtered, the sensitivity near the step 23 in the concave portion 22 is reduced. Voids and the like are likely to be formed in the film 24 . Further, when the slope of the step 23 is steep, when the solvent containing the sensitive film 24 is applied to the concave portion 22, uneven coating occurs near the step 23, and the thickness of the sensitive film 24 tends to vary. Therefore, the sensitivity of the sensitive film 24 becomes uneven. In Example 1, the slope of the step 23 can be made gentler than the slope of the step 26a. This can suppress the formation of voids near the step 23, variations in the thickness of the sensitive film 24, and the like. Therefore, the sensitivity of the sensitive film 24 can be made uniform.
図3(c)のように、圧電膜14をパターニングするときに、圧電膜14をエッチングするエッチング液が挿入膜28と上部圧電膜14bとの間の界面、および上部圧電膜14bと上部電極16との間の界面に侵入することがある。実施例1では、挿入膜28の上面に段差26aが設けられているため、エッチング液が挿入膜28と上部圧電膜14bとの間の界面に侵入することを抑制できる。上部圧電膜14bの上面に段差27aが設けられているため、エッチング液が上部圧電膜14bと上部電極16との間の界面に侵入することを抑制できる。なお、圧電膜14をエッチングするとき以外の工程等においても、溶液が挿入膜28と上部圧電膜14bとの間の界面および上部圧電膜14bと上部電極16との界面に侵入することを抑制できる。
As shown in FIG. 3C, when the piezoelectric film 14 is patterned, an etchant for etching the piezoelectric film 14 is applied to the interface between the insertion film 28 and the upper piezoelectric film 14b, and the upper piezoelectric film 14b and the upper electrode 16. can penetrate the interface between In Example 1, since the step 26a is provided on the upper surface of the insertion film 28, it is possible to prevent the etchant from entering the interface between the insertion film 28 and the upper piezoelectric film 14b. Since the step 27a is provided on the upper surface of the upper piezoelectric film 14b, the etchant can be prevented from entering the interface between the upper piezoelectric film 14b and the upper electrode 16. FIG. It is possible to prevent the solution from entering the interface between the insertion film 28 and the upper piezoelectric film 14b and the interface between the upper piezoelectric film 14b and the upper electrode 16 in steps other than the etching of the piezoelectric film 14. .
図2(c)のように、挿入膜28を形成する前では、下部圧電膜14aの上面の凸凹が小さい。このため、特許文献1の図17(b)の保護膜のダムを形成するときに保護膜の上面の凸凹が大きいことにより生じる上述の問題を抑制できる。
As shown in FIG. 2(c), before the insertion film 28 is formed, the unevenness of the upper surface of the lower piezoelectric film 14a is small. Therefore, it is possible to suppress the above-described problem caused by the large unevenness of the upper surface of the protective film when forming the dam of the protective film in FIG. 17(b) of Patent Document 1.
表2は、検出素子の上部電極16上に感応膜24として、有機低分子材料である銅フタロシアニン(CuPc)の場合における、膜厚とTCFをまとめた表である。
Table 2 summarizes film thickness and TCF in the case of copper phthalocyanine (CuPc), which is an organic low-molecular material, as the sensitive film 24 on the upper electrode 16 of the detection element.
表2に示すように、感応膜24の膜厚が厚くなるほどにTCFが±0よりマイナス側に大きくなっている。このように、検出素子は上部電極16上に形成した感応膜24の材料によってTCFが変化する。このため、感応膜24のTCFを±0に近づけるように薄膜部28bの厚さTbを調整する必要がある。薄膜部28bの厚さTbは、検出素子の共振周波数のTCF(周波数温度係数)が-20ppm/K以上かつ20ppm/K以下となるように設定することが好ましい。これにより、実験5の図13のように、検出素子を動作させたときに、共振器の特性を安定にすることができる。TCFは、-10ppm/K以上かつ10ppm/K以下がより好ましく、-5ppm/K以上かつ5ppm/K以下がさらに好ましい。
As shown in Table 2, as the film thickness of the sensitive film 24 increases, the TCF increases from ±0 to the negative side. In this manner, the TCF of the detection element changes depending on the material of the sensitive film 24 formed on the upper electrode 16 . Therefore, it is necessary to adjust the thickness Tb of the thin film portion 28b so that the TCF of the sensitive film 24 approaches ±0. The thickness Tb of the thin film portion 28b is preferably set so that the TCF (frequency temperature coefficient) of the resonance frequency of the detection element is -20 ppm/K or more and 20 ppm/K or less. Thereby, as shown in FIG. 13 of Experiment 5, the characteristics of the resonator can be stabilized when the detection element is operated. The TCF is more preferably -10 ppm/K or more and 10 ppm/K or less, and more preferably -5 ppm/K or more and 5 ppm/K or less.
[実施例1の変形例1]
実施例1の変形例1および2は、空隙の構成を変えた例である。図15(a)は、実施例1の変形例1に係る検出素子の断面図である。図15(a)に示すように、基板10の上面に窪みが形成されている。下部電極12は、基板10上に平坦に形成されている。これにより、空隙30が、基板10の窪みに形成されている。空隙30は共振領域50を含むように形成されている。その他の構成は、実施例1と同じであり説明を省略する。空隙30は、基板10を貫通するように形成されていてもよい。 [Modification 1 of Embodiment 1]
Modifications 1 and 2 of Example 1 are examples in which the structure of the gap is changed. 15A is a cross-sectional view of a detection element according to Modification 1 of Example 1. FIG. As shown in FIG. 15(a), a recess is formed in the upper surface of the substrate 10. As shown in FIG. The lower electrode 12 is formed flat on the substrate 10 . Thereby, a void 30 is formed in the depression of the substrate 10 . Air gap 30 is formed to include resonance region 50 . Other configurations are the same as those of the first embodiment, and description thereof is omitted. The void 30 may be formed to penetrate the substrate 10 .
実施例1の変形例1および2は、空隙の構成を変えた例である。図15(a)は、実施例1の変形例1に係る検出素子の断面図である。図15(a)に示すように、基板10の上面に窪みが形成されている。下部電極12は、基板10上に平坦に形成されている。これにより、空隙30が、基板10の窪みに形成されている。空隙30は共振領域50を含むように形成されている。その他の構成は、実施例1と同じであり説明を省略する。空隙30は、基板10を貫通するように形成されていてもよい。 [
[実施例1の変形例2]
図15(b)は、実施例1の変形例2に係る検出素子の断面図である。図15(b)に示すように、共振領域50の下部電極12下に音響反射膜31が形成されている。音響反射膜31は、音響インピーダンスの低い膜31aと音響インピーダンスの高い膜31bとが交互に設けられている。膜31aおよび31bの膜厚は例えばそれぞれほぼλ/4(λは弾性波の波長)である。膜31aと膜31bの積層数は任意に設定できる。音響反射膜31は、音響特性の異なる少なくとも2種類の層が間隔をあけて積層されていればよい。また、基板10が音響反射膜31の音響特性の異なる少なくとも2種類の層のうちの1層であってもよい。例えば、音響反射膜31は、基板10中に音響インピーダンスの異なる膜が一層設けられている構成でもよい。その他の構成は、実施例1と同じであり説明を省略する。 [Modification 2 of Embodiment 1]
15B is a cross-sectional view of a detection element according toModification 2 of Example 1. FIG. As shown in FIG. 15(b), an acoustic reflection film 31 is formed under the lower electrode 12 in the resonance region 50. As shown in FIG. The acoustic reflection film 31 is alternately provided with films 31a with low acoustic impedance and films 31b with high acoustic impedance. The thickness of the films 31a and 31b is, for example, approximately λ/4 (λ is the wavelength of the acoustic wave). The number of layers of the films 31a and 31b can be set arbitrarily. The acoustic reflection film 31 may be formed by stacking at least two types of layers with different acoustic properties with a gap therebetween. Also, the substrate 10 may be one of at least two layers having different acoustic characteristics of the acoustic reflection film 31 . For example, the acoustic reflection film 31 may have a structure in which one film having a different acoustic impedance is provided in the substrate 10 . Other configurations are the same as those of the first embodiment, and description thereof is omitted.
図15(b)は、実施例1の変形例2に係る検出素子の断面図である。図15(b)に示すように、共振領域50の下部電極12下に音響反射膜31が形成されている。音響反射膜31は、音響インピーダンスの低い膜31aと音響インピーダンスの高い膜31bとが交互に設けられている。膜31aおよび31bの膜厚は例えばそれぞれほぼλ/4(λは弾性波の波長)である。膜31aと膜31bの積層数は任意に設定できる。音響反射膜31は、音響特性の異なる少なくとも2種類の層が間隔をあけて積層されていればよい。また、基板10が音響反射膜31の音響特性の異なる少なくとも2種類の層のうちの1層であってもよい。例えば、音響反射膜31は、基板10中に音響インピーダンスの異なる膜が一層設けられている構成でもよい。その他の構成は、実施例1と同じであり説明を省略する。 [
15B is a cross-sectional view of a detection element according to
実施例1およびその変形例1のように、検出素子に用いる圧電薄膜共振器は、共振領域50において空隙30が基板10と下部電極12との間に形成されているFBAR(Film Bulk Acoustic Resonator)でもよい。また、実施例1の変形例2のように、圧電薄膜共振器は、共振領域50において下部電極12下に圧電膜14を伝搬する弾性波を反射する音響反射膜31を備えるSMR(Solidly Mounted Resonator)でもよい。共振領域50を含む音響反射層は、空隙30または音響反射膜31を含めばよい。
As in Example 1 and its modification 1, the piezoelectric thin film resonator used for the detection element is an FBAR (Film Bulk Acoustic Resonator) in which the air gap 30 is formed between the substrate 10 and the lower electrode 12 in the resonance region 50. It's okay. Further, like the modification 2 of the embodiment 1, the piezoelectric thin film resonator includes an SMR (Solidly Mounted Resonator) including an acoustic reflection film 31 that reflects an elastic wave propagating through the piezoelectric film 14 under the lower electrode 12 in the resonance region 50. ) can be used. The acoustic reflection layer including the resonance region 50 may include the void 30 or the acoustic reflection film 31 .
共振領域50の平面形状として楕円形状を例に説明したが、共振領域50の平面形状は、四角形状または五角形状等の多角形状等の任意の形状でもよい。
Although an elliptical shape has been described as an example of the planar shape of the resonance region 50, the planar shape of the resonance region 50 may be any shape such as a square shape, a polygonal shape such as a pentagonal shape, or the like.
実施例2は、実施例1およびその変形例の検出素子を備える検出システムの例である。図16は、本実施形態に係る匂い検出装置100の構成を示すブロック図である。図16に示すように匂い検出装置100は、匂い検出部110と制御部120を備える。匂い検出部110は、チャンバ111、検出素子112、湿度センサ113、温度センサ114、第1ポンプ115、第2ポンプ116およびフィルタ117を備える。 チャンバ111は、検出素子112、湿度センサ113および温度センサ114を収容する。チャンバ111には第1吸入口111a、第2吸入口111bおよび排出口111cが設けられている。
Example 2 is an example of a detection system including the detection elements of Example 1 and its modifications. FIG. 16 is a block diagram showing the configuration of the odor detection device 100 according to this embodiment. As shown in FIG. 16 , the odor detection device 100 includes an odor detection section 110 and a control section 120 . Odor detection unit 110 includes chamber 111 , detection element 112 , humidity sensor 113 , temperature sensor 114 , first pump 115 , second pump 116 and filter 117 . Chamber 111 accommodates sensing element 112 , humidity sensor 113 and temperature sensor 114 . The chamber 111 is provided with a first inlet 111a, a second inlet 111b and an outlet 111c.
検出素子112はチャンバ111内に収容され、チャンバ111内に供給された気体に含まれる匂い成分を検出する。検出素子112は、匂い成分が吸着することにより匂い成分を検出可能なセンサであり、図1(a)および図1(b)のように、上部電極16表面に検出対象成分を吸着するための感応膜24が設けられた構成を有する。感応膜24表面に匂い成分が吸着すると、その質量に応じて共振周波数が変動する(下がる)ため、微量な質量変化を検出することができる。
The detection element 112 is housed inside the chamber 111 and detects the odor component contained in the gas supplied inside the chamber 111 . The detection element 112 is a sensor capable of detecting an odor component by adsorbing the odor component, and as shown in FIGS. It has a configuration in which a sensitive film 24 is provided. When an odor component is adsorbed on the surface of the sensitive film 24, the resonance frequency fluctuates (decreases) according to the mass of the odor component, so a minute change in mass can be detected.
検出素子112が検出する匂い成分は、典型的には高分子化合物等の空気中において比較的重い分子であるが、特に限定されない。検出素子112が検出する匂い成分は人間が嗅覚で感知可能な成分に限られず、気体中に存在する化学種であればよい。
The odor components detected by the detection element 112 are typically relatively heavy molecules in the air, such as polymer compounds, but are not particularly limited. The odor component detected by the detection element 112 is not limited to a component that can be sensed by human sense of smell, and may be a chemical species present in gas.
図16に示すように匂い検出装置100は、チャンネル1(ch1)からチャンネル16(ch16)まで16個の検出素子112を備える。各検出素子112はそれぞれが異なる感応膜24を備え、それぞれに異なる匂い成分が吸着するものとすることができる。すなわち、検出素子112は複数設けられ、複数の検出素子112のうち少なくとも2つの検出素子112における感応膜24は異なる材料から形成されていてもよい。匂い検出装置100が備える検出素子112の数は特に限定されず、1つ以上であればよい。
As shown in FIG. 16, the odor detection device 100 includes 16 detection elements 112 from channel 1 (ch1) to channel 16 (ch16). Each detection element 112 may have a different sensitive film 24 to adsorb different odor components. That is, a plurality of detection elements 112 may be provided, and the sensitive films 24 of at least two detection elements 112 among the plurality of detection elements 112 may be made of different materials. The number of detection elements 112 included in the odor detection device 100 is not particularly limited, and may be one or more.
湿度センサ113と温度センサ114は、チャンバ111内に収容され、チャンバ111内の湿度と温度を検出する。湿度センサ113と温度センサ114の種類は特に限定されない。
A humidity sensor 113 and a temperature sensor 114 are housed inside the chamber 111 and detect the humidity and temperature inside the chamber 111 . The types of humidity sensor 113 and temperature sensor 114 are not particularly limited.
次にポンプについて記載する。第1ポンプ115は、第1吸入口111aに接続され、第1吸入口111aを介してチャンバ111内に気体を送出する。第1ポンプ115は例えばダイアフラムポンプとすることができるが他のポンプであってもよい。第2ポンプ116は、第2吸入口111bに接続され、第2吸入口111bを介してチャンバ111内に気体を送出する。第2ポンプ116は例えばダイアフラムポンプとすることができるが他のポンプであってもよい。なお、図16では第1ポンプ115や第2ポンプ116を使用しているが、これらのポンプはなくてもよい。
Next, I will describe the pump. The first pump 115 is connected to the first inlet 111a and pumps gas into the chamber 111 through the first inlet 111a. The first pump 115 may be, for example, a diaphragm pump, but may also be another pump. The second pump 116 is connected to the second inlet 111b and pumps gas into the chamber 111 through the second inlet 111b. The second pump 116 can be, for example, a diaphragm pump, but can also be other pumps. Although the first pump 115 and the second pump 116 are used in FIG. 16, these pumps may be omitted.
フィルタ117は、第2吸入口111bに接続され、第2吸入口111bを介してチャンバ111内に流入する気体から匂い成分を除去する。フィルタ117は少なくともの各検出素子112の検出対象である匂い成分を除去可能な構成を有する。また、フィルタ117は水分子を除去可能なものが好適である。
The filter 117 is connected to the second suction port 111b and removes odor components from the gas flowing into the chamber 111 through the second suction port 111b. The filter 117 has a configuration capable of removing at least the odor component that is the detection target of each detection element 112 . Moreover, it is preferable that the filter 117 can remove water molecules.
制御部120は、匂い検出部110と接続され、匂い検出部110の出力を演算処理する。図16に示すように制御部120は、取得部121、演算部122、判定部123および記憶部124を備える。取得部121は、図16に示すように各検出素子112、湿度センサ113および温度センサ114と接続され、各センサの出力を取得する。取得部121と各センサの接続は有線でも無線でもよい。取得部121は、取得した各センサの出力を演算部122に供給する。演算部122は、取得部121から供給された各センサの出力を用いて、演算処理を実行し、算出結果を判定部123に供給する。
The control unit 120 is connected to the odor detection unit 110 and arithmetically processes the output of the odor detection unit 110 . As shown in FIG. 16 , control unit 120 includes acquisition unit 121 , calculation unit 122 , determination unit 123 and storage unit 124 . Acquisition unit 121 is connected to each detection element 112, humidity sensor 113, and temperature sensor 114 as shown in FIG. 16, and acquires the output of each sensor. The connection between the acquisition unit 121 and each sensor may be wired or wireless. The acquisition unit 121 supplies the acquired output of each sensor to the calculation unit 122 . The calculation unit 122 performs calculation processing using the output of each sensor supplied from the acquisition unit 121 and supplies the calculation result to the determination unit 123 .
判定部123は、演算部122から供給された算出結果を用いて匂い成分の判定を実行する。判定部123は匂い成分の有無、匂い成分の濃度、匂いの種類および匂いの強度のうち少なくともいずれか一つを判定することができる。判定部123は判定結果と匂い検出部110による測定結果を記憶部124に供給する。記憶部124は、判定部123による判定結果と匂い検出部110による測定結果を記憶する。
The determination unit 123 uses the calculation result supplied from the calculation unit 122 to determine the odor component. The determination unit 123 can determine at least one of the presence or absence of an odor component, the concentration of the odor component, the type of odor, and the intensity of the odor. The determination unit 123 supplies the determination result and the measurement result by the odor detection unit 110 to the storage unit 124 . Storage unit 124 stores the result of determination by determination unit 123 and the result of measurement by odor detection unit 110 .
上述した制御部120の各構成は、プロセッサおよびメモリ等のハードウェアとソフトウェアの協働により実現される機能的構成であり、その実現態様は特に限定されない。即ち制御部120は、匂い検出部110と一体的に構成された情報処理ユニットによって実現されてもよく、匂い検出部110とは独立した情報処理ユニットによって実現されてもよい。また、制御部120の各機能的構成はネットワークを介して接続された複数の情報処理ユニットによって実現されてもよい。なお、検出素子は、図15(a)および図15(b)に示した変形例1または2の検出素子を使用してもよい。
Each configuration of the control unit 120 described above is a functional configuration realized by cooperation of hardware such as a processor and memory and software, and the implementation mode is not particularly limited. That is, the control section 120 may be implemented by an information processing unit configured integrally with the odor detection section 110 or may be implemented by an information processing unit independent of the odor detection section 110 . Moreover, each functional configuration of the control unit 120 may be implemented by a plurality of information processing units connected via a network. In addition, the detection element of the modification 1 or 2 shown in FIG.15(a) and FIG.15(b) may be used for a detection element.
検出素子112を用いる検出システムとしては、検出素子112の出力する信号に基づき、環境の変化を検出する検出システムであればよい。
A detection system using the detection element 112 may be any detection system that detects changes in the environment based on the signal output by the detection element 112 .
以上、本発明の実施例について詳述したが、本発明はかかる特定の実施例に限定されるものではなく、特許請求の範囲に記載された本発明の要旨の範囲内において、種々の変形・変更が可能である。
Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations can be made within the scope of the gist of the present invention described in the scope of claims. Change is possible.
10 基板
12 下部電極
14 圧電膜
14a 下部圧電膜
14b 上部圧電膜
16 上部電極
22、26、27 凹部
23、26a、27a 段差
24 感応膜
28 挿入膜
28a 厚膜部
28b 薄膜部
REFERENCE SIGNSLIST 10 substrate 12 lower electrode 14 piezoelectric film 14a lower piezoelectric film 14b upper piezoelectric film 16 upper electrode 22, 26, 27 concave portions 23, 26a, 27a step 24 sensitive film 28 insertion film 28a thick film portion 28b thin film portion
12 下部電極
14 圧電膜
14a 下部圧電膜
14b 上部圧電膜
16 上部電極
22、26、27 凹部
23、26a、27a 段差
24 感応膜
28 挿入膜
28a 厚膜部
28b 薄膜部
REFERENCE SIGNS
Claims (13)
- 基板と、
前記基板上に設けられた圧電膜と、
前記圧電膜の少なくとも一部を挟んで対向した下部電極および上部電極と、
前記圧電膜の少なくとも一部を挟み前記下部電極と前記上部電極とが対向する領域により画定される共振領域内の前記下部電極と前記上部電極との間に設けられ、平面視において前記共振領域より内側に設けられた薄膜部と、平面視において前記薄膜部を囲み前記共振領域の周縁に設けられ前記薄膜部より厚い厚膜部と、を備える挿入膜と、
前記上部電極の上面に設けられた前記薄膜部と前記厚膜部とにより画定された第1段差で囲まれた領域に設けられた感応膜と、
を備え、
環境の変化により共振周波数が変化する検出素子。 a substrate;
a piezoelectric film provided on the substrate;
a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film interposed therebetween;
provided between the lower electrode and the upper electrode in a resonance region defined by a region in which the lower electrode and the upper electrode face each other with at least part of the piezoelectric film interposed therebetween, and is located from the resonance region in a plan view. an insertion film comprising a thin film portion provided inside, and a thick film portion surrounding the thin film portion and provided at the periphery of the resonance region in plan view and having a thickness greater than that of the thin film portion;
a sensitive film provided in a region surrounded by a first step defined by the thin film portion and the thick film portion provided on the upper surface of the upper electrode;
with
A sensing element whose resonance frequency changes according to changes in the environment. - 前記薄膜部の弾性定数の温度係数の符号は前記圧電膜の弾性定数の温度係数の符号とは反対である請求項1に記載の検出素子。 The sensing element according to claim 1, wherein the sign of the temperature coefficient of the elastic constant of the thin film portion is opposite to the sign of the temperature coefficient of the elastic constant of the piezoelectric film.
- 前記厚膜部は、前記圧電膜のヤング率よりヤング率の小さい膜を含む請求項2に記載の検出素子。 The detection element according to claim 2, wherein the thick film portion includes a film having a Young's modulus smaller than that of the piezoelectric film.
- 前記圧電膜は窒化アルミニウム膜を主成分とし、前記挿入膜は酸化シリコンを主成分とする請求項1に記載の検出素子。 The sensing element according to claim 1, wherein the piezoelectric film is mainly composed of an aluminum nitride film, and the insertion film is mainly composed of silicon oxide.
- 前記圧電膜は、前記下部電極上に設けられた下部圧電膜と、前記下部圧電膜上に設けられた上部圧電膜と、を備え、前記挿入膜は前記下部圧電膜と前記上部圧電膜との間に設けられている請求項1から4のいずれか一項に記載の検出素子。 The piezoelectric film includes a lower piezoelectric film provided on the lower electrode and an upper piezoelectric film provided on the lower piezoelectric film, and the insertion film is formed between the lower piezoelectric film and the upper piezoelectric film. 5. A sensing element according to any one of claims 1 to 4, provided between.
- 前記厚膜部の厚さは前記薄膜部の厚さの1.5倍以上である請求項1から4のいずれか一項に記載の検出素子。 The detection element according to any one of claims 1 to 4, wherein the thickness of the thick film portion is 1.5 times or more the thickness of the thin film portion.
- 前記検出素子の共振周波数の温度周波数係数は-20ppm/K以上かつ20ppm/K以下である請求項1から4のいずれか一項に記載の検出素子。 The detection element according to any one of claims 1 to 4, wherein the temperature frequency coefficient of the resonance frequency of the detection element is -20 ppm/K or more and 20 ppm/K or less.
- 前記挿入膜の上面に、前記薄膜部の上面が前記厚膜部の上面より前基板側に凹むように第2段差が設けられ、
前記圧電膜の上面に、前記薄膜部に対応する前記圧電膜の上面が前記厚膜部に対応する前記圧電膜の上面より前記基板側に凹むように第3段差が設けられ、
前記第1段差は、前記薄膜部に対応する前記上部電極の上面が前記厚膜部に対応する前記上部電極より前記基板側に凹むように設けられている請求項1から4のいずれか一項に記載の検出素子。 A second step is provided on the upper surface of the insertion film so that the upper surface of the thin film portion is recessed toward the front substrate from the upper surface of the thick film portion,
A third step is provided on the upper surface of the piezoelectric film so that the upper surface of the piezoelectric film corresponding to the thin film portion is recessed toward the substrate from the upper surface of the piezoelectric film corresponding to the thick film portion,
5. The first step is provided so that the upper surface of the upper electrode corresponding to the thin film portion is recessed toward the substrate from the upper electrode corresponding to the thick film portion. The detection element according to . - 前記第1段差の傾斜は前記第2段差の傾斜より緩やかである請求項8に記載の検出素子。 The detection element according to claim 8, wherein the slope of the first step is gentler than the slope of the second step.
- 請求項1から4のいずれか一項に記載の検出素子と、
前記検出素子の出力する信号に基づき、前記環境の変化を検出する検出システム。 A detection element according to any one of claims 1 to 4;
A detection system for detecting a change in the environment based on a signal output from the detection element. - 前記検出素子は複数設けられ、前記複数の検出素子のうち少なくとも2つの検出素子における前記感応膜は異なる材料から形成される請求項10に記載の検出システム。 11. The detection system according to claim 10, wherein a plurality of said detection elements are provided, and said sensitive films in at least two of said plurality of detection elements are made of different materials.
- 基板上に設けられた圧電膜と、前記圧電膜の少なくとも一部を挟んで対向した下部電極および上部電極と、前記圧電膜の少なくとも一部を挟み前記下部電極と前記上部電極とが対向する領域により画定される共振領域内の前記下部電極と前記上部電極との間に設けられ、前記共振領域より内側に設けられた薄膜部と平面視において前記薄膜部を囲み前記共振領域の周縁に設けられ前記薄膜部より厚い厚膜部とを備える挿入膜と、を備える共振器を作製する工程と、
前記上部電極の上面に設けられた前記薄膜部と前記厚膜部とにより画定された段差で囲まれた領域に、環境の変化により質量が変化する感応膜を形成する工程と、
を含む検出素子の製造方法。 A piezoelectric film provided on a substrate, a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film therebetween, and a region where the lower electrode and the upper electrode face each other with at least a portion of the piezoelectric film therebetween. is provided between the lower electrode and the upper electrode in a resonance region defined by a thin film portion provided inside the resonance region and a thin film portion provided on the periphery of the resonance region surrounding the thin film portion in plan view a step of fabricating a resonator comprising: an insertion film comprising a thick film portion thicker than the thin film portion;
a step of forming a sensitive film whose mass changes with environmental changes in a region surrounded by a step defined by the thin film portion and the thick film portion provided on the upper surface of the upper electrode;
A method of manufacturing a sensing element comprising: - 前記感応膜を形成する工程は、感応剤を含む溶剤を塗布する工程を含む請求項12に記載の検出素子の製造方法。
13. The method of manufacturing a detection element according to claim 12, wherein the step of forming the sensitive film includes a step of applying a solvent containing a sensitive agent.
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