PN结自停止技术

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1、IEEETRANSACTIONSONELECTRONDEVICES.VOL.36.NO.4.APRIL1989663StudyofElectrochemicalEtch-StopforHigh-PrecisionThicknessControlofSiliconMembranesBENKLOECK,SCOTTD.COLLINS,NICOF.DEROOIJ,ANDROSEMARYL.SMITHAbstract-Amethodisdescribedtocontrolthethicknessofsingle-0.6crystalsiliconmembranes,fabric

2、atedbywetanisotropicetching.The-techniqueofanelectrochemicaletch-stoponanepitaxiallayerisused50.4toyieldbetterthicknesscontroloverthesiliconmembranes(k0.2pmas.d.)andhenceimprovethereproducibilityofpiezoresistivepressure0.2sensors.Althoughtheelectrochemicaletch-stopisnotnew,thispaper-x-r

3、eportsthecharacterizationandevaluationofthetechniqueasafab-v)koricationprocess.Theoutputcharacteristicsofpiezoresistivepressure-sensorsfabricatedusingtheelectrochemicaletch-stoptechniqueareCg-0.2comparedwithpreviouslyfabricatedpressusresensorsnotutilizingac-30curatecontrolovermembraneth

4、ickness.Thebenefitsoftheetch-stop-0.4approachbecomeapparentwhenreductionsinthepressure-sensitivityivariationsareconsidered.Withoutetch-stop,thesensitivityonone1.6-1.2-0.8-0400.4wafervariedbyafactoroftwofromonesensortotheother.WithPotential(V)etch-stop,thepressuresensitivityofdevicesfabr

5、icatedonthesameFig.1.TheelectrochemicalIIVcharacteristicsofp-(-)andn-typewafercanbecontrolledtowithin+4percents.d.(----)(100)orientedsilicon,in40-percentKOHaqueoussolutionat60°Catasweeprateof1mV/s.PPisthepassivationpotentialofp-typesiliconandOFPistheoxideformationpotentialofn-typesilico

6、n.I.INTRODUCTIONand*areworkingpointsforthesubstrateandistheworkingpointfortheepitaxiallayerduringfour-electrodeetching.ALARGEclassofsensorsandactuatorsusemicro-machinedsiliconstructuresassensingoractiveele-canthenbepreciselycontrolledbytakingadvantageofments.Theminiaturizationofthesedev

7、icestoanevercurrentsilicondiodefabricationtechnologies.Theresultsmallerscaleincreasestherequirementsfordimensionalisthatetchingcanbestoppedatawelldefinedp-njunc-controlofmicromachinedcomponentssuchasmem-tion.Toachievethis,apositivevoltageisapplieddirectlybranes,cantileverbeams,