关于低功耗气体传感器阵列的研究

1、关于低功耗气体传感器阵列的研究第19卷第1期2006年2月传感技术ACrUAT0RSResearchonthePowerConsumptionofGas-SensorArrayLISong,MartinJaegle.,HaraldBoettner./1.CollegeofPrecisionInstrument,TiainUniversity,Tiain300072,ChinaI,2.FraunhoferInstituteofPhysicalMeasurement,79110Freiburg,Germany/searchthepowerconsumptionofgassensors,oftent

2、hefrontsideofthesensorarrayhasfabricated,thepowerconsumption.Keywords:lOWpowerconsumption;gassensor;sensorarray;airgapEEACC:72301关于低功耗气体传感器阵列的研究李松,MartinJaegle,HaraldBoettner(2:天Fr津aun大h学ofe精r仪Ins学tit院uteo天f津Phy.s00ic.a乳Measurement,79110,Freiburg,Germany).1,摘要:由电池驱动以微机械技术制造的气体传感器的功耗是十分关键的实际问题.为了研制低功

3、耗气体传感器,在传感空气夹层的传感器芯片和没有空气夹层的传感器芯片的能耗做比拟.实验结果显示,腐蚀过的传感器芯片具有较低的功耗.关键词:低功耗;气体传感器;传感器阵列;空气夹层中图分类号:TP212文献标识码:A文章编号:1OO5949O(2Oo6)O1-I)O57-I)3Metaloxidegassensorshavealotofadvantages,suchasportability,lowcost,simplesignalmeasurementofmetaloxide1ayersdepositedonheatedsubstrates.Normallytheworkingtemperatu

4、reis100500.thusimpliesanamountofpowerconsumptionthatmakesabattery-drivenscreen-printedgassensorsistypicallyintherangeof200mWtoabout1W1】.Thisleadstothedevelopmentofmicromativelayerofmicro-machinedmetaloxidegassensorsiSdepositedontoathindielectricmembraneofthermalisolationbetweensubstrateandthegas-the

5、powerconsumptioncanbekeptverylow(typicalvalueslieintherangebetween30and150mW-2-4)andthesubstrateitselfstaysnearlyatambicandecreasepowerconsumptionbyusingdecreasedsensorareaevenwithseveralsensingele-importantfactorsfordesigningsensorarrays.Normallythermaltransferoccursduetoheatconduction,convectionan

6、dradiation,andtheair收稿日期:200507-2558传感技术2006虽mentalworksonlyconcentateontheIPM(FraunhoferInstituteofPhysicalMeasurement)micromachinedintegratedlowpowergassensorarrays.Thewaferisetchedfromthebacksidesothatanairgapcanbeobtainedbetweenthesensorchipandthehousing,whichlcadstoathermalinsulationandthusdecr

7、easespowerconsumption.1SensorStructureFabricationThebasestructureisproducedona4一inchsiliconwafer,whichis500mSilicon(Si)with1mthermaloxidizedsilicondioxide(SiO2)onbothtopchipis3mm3mmwithfoursensingelements.First,Platinumelectrodes,temperaturesensorandheateraredepositedbyelectronbeamevaporation.Thenth

8、esensingmaterials(SnO2)aredeposited.Interdigitalelectrodes(Pt,200nmthick)providetheelectricalcontacttothesemiconductingfilm.Theplatinumresistancelayerinthecenterofthearrayheatsthesensortoitsworkingtemperature(100-500),alsoaplatinumtemperaturesensorislocatedinsideE.2BacksideEtchingTodecreasepowercons

9、umption,thermalconfromthebacksidesothatanairgapcanbeobtainedbetweenthesensorchipandthehousing,whichlcadstoathermalinsulationandthusdecreasespowerconsumption.structuresonthefrontsidehavetobeprotectedaremadebythinfilmtechnology,aprocessing(e.g.photolithOgrapy,lift-off)ofthesensorontothehotplateisnotpo

10、ssibleafterthehotplateetching,becausethestructuresaretoofragile.Experimentswithsensorarrayswhichareetchedfromthebacksidearedescribedinthefollowing.Forreasonsofcomparability,notcom-pletewafersareprocessed,butfractionsofthewafersareetchedandothersareleftunetched.Forthesiliconetching,theinsulatingsilic

11、onetchedwithhydrofluoricacid(HF).Alsoherethetedonthefrontsideofthewaferasapassivationlayerandonthebacksideforphotolithograpy-Fig.1(a).Afterexposureanddevelopment,thefeetstructureisonthebacksideFig.1(b).BeforeHFetching,thewaferiShardbakedfor20minutestomakethephotoresistwithstandtheHF(a)(c)叠警墨墨Photore

12、sist匿翟囫SiO.(e)(b)PtSiTaA1d)圈卿强黜Sn0,blacl(waxetchantforSiO2etching,afterthat,thephotore-sistisremovedbytheacetone-Fig.1(c).Nowthewaferisreadyforthesiliconetching.Priortofurtherprocessing,thewaferisbrokenintopieces,whichcanbetakenforfurtherprocessing.Foranisotropicetching,therearedifferentetchants,KOH

13、,EDP(Ethylenediaminepyrocatecho1),TMAH(Tetramethylammoniumhydroxide),etc.AsKOHetchesSiO2toofast,theetchingselectivitybetweenSiandSiO2isbad,thiscausesSi02feetvanishingafterdeepSietchtudelowerthanforSi(100)in90TMAH.buttheetchrateforSi(100)withTMAHislower第1期李松,MartinJaegle等:关于低功耗气体传感器阵列的研究59(ApiezonWax

14、W*)isselectedasapassivationmaterial,sinceitsmeltingpointis85,anditcanbeusedforprotectiontoTMAHandKOHuptoatemperatureof70.AfterblackwaxpassivationFig.1(d),twosetsofwaferpiecesareetchedrespectivelyinTMAHandKOHat7Opensationforthebacksidefeetmask,thesiliconisetchedonly140mdeep,whichissufficientforanforK

15、OHetchantand10hoursforTMAHetchK0Hischosenasetchant,sinceitisfasterthanHandeavesmorefeetsizethanHAfterK0Hetching,blackwaxisremovedFig.1(e).Table1ComparisonoffeetdimensionbeforeandafteretchinginKOHandTMAIL3Measurementsumptionofetchedandunetchedsensorsfromtheuredsensorsaresuppliedwith14V,16Vand18【J,?(U

16、issupplyvoltage,Iisheatercurrent).sonforetchedandunetchedsensorsatdifferentsupplyvoltages,etchedsensorshavelowerpowerconsumptionatdifferentworkingtemperatureforetchedsensors(twosets)andunetchedsensors(twosets),evenathigherworkingtemperaturetheetchedsensorsshowlowerpowerconsumptionduetothebettertherm

17、alinsulation.4SummaryThebestwaytodecreasethepowerconsumptionofgassensorsistominimizethethermallostweensiliconsubstrateandglassspacers,theyhavemorethermaIconductionthanetchedsensors.Afterbacksideetching,anairgapbetweenthesupplyvoltages.workingtemperature.*ApiezonisatrademarkofM&lMaterialsItetched

18、sensorshavelowerpowerconsumptionduetodecreasedthermalconduction.参考文献:21-33567FigaroProductsCatalogue,FigaroGasSensors2000一Seriesz,FigaroEngineeringInc.,EuropeanOffice,Oststrasse10,40211Duesseldorf,Germany.AnalysisandDesignofaMicro-HotplateforIntegratedGasSensorApplicationsI-J.Sens.ActuatorsA54(1996)482487.Taniayo,LHorril一1o,G.Getino,C.Gracia,J.Gutierez,AMicromachinedSolidStateIntegratedGasSensorfortheDetectionofAromaticHydrocarbonsJj.Sen