集成电路制造工艺课件04_氧化

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1、2013-10-12ApplicationofSiliconDioxide•OxideinaMOSFETpassivationoxideOxidationandSi/SiO2interfaceisolationoxideImplantmaskgateoxide•OxideinIC-Insulatingbetweenconductionlayers-IsolateadjacentdevicesProf.MingxiangWANG-Maskinglayerinvariousprocesses•High

2、resistivity>1020Ω-cm•Highbreakdownelectricfield>10MV/cm•Largeenergybandgap:Eg~9eV2/23StructureofSiOFilms2•Basicunit:SiO44-tetrahedra•Quartzcrystal---orderednetworkofbasicunitSiO44-•SiO2filmsinIC---amorphousstate•Nolongrangeorder,withshortrangeorder(si

3、milartoglass)•Verystable,goodSi/SiO2interfaceInterlayerdielectricoxygensiliconIsolationCrystallineSiO2(quartz)=2.65g/cm3AmorphousSiO(thermaloxide)=2.2g/cm3schemes23/234/2312013-10-12ThermalOxidationofSiliconOxidationFurnaceChemicalreactionofthermaloxi

4、dation–Dryoxidation:Si(s)+O2(g)SiO2(s)–Wetoxidation:Si(s)+2H2O(g)SiO2(s)+2H2(g)--Typicallycarriedoutat700-1200℃oxideformed@interface–Oxidequalitydependson:•Substratepurity(wafercleaning)•Gaspurity•Oxidationprocess–Wetoxidationismuchfaster,H2Omolecul

5、eissmallerthanO2andeasiertodiffusethroughSiO2film,solubility3GasoptionsofH2OinSiO2is~10higherthanO25/236/23SiConsumptionCharacteristicsofOxidationoriginalsurfacetoxSiO2-DryoxidationtendstoproducebetteroxidequalityandSi/SiO2interface.SiSi-Goodinterface

6、betweenSi/SiO2makeSitechnologysuperioroverothersemiconductormaterialsofchoice•NumberofSiatomsdoesnotchange-Inwetoxidation,usuallya5-minutedryoxidationbeforetSiNSi=toxNoxandafterwetoxidationisaddedtoimproveoxidequalityNSi---SidensityinSi(=5x1022atoms/c

7、m3)“dry-wet-dry”scheme-Afteroxidation,thereactionshouldbestabilizedbyNox---SidensityinSiO2(=2.2x1022atoms/cm3)annealingininertambient(N2orAr)toallowsomelocal22atomsre-arrangementwithoutfurtherSiO2formation.2.2101unitIthelpstoreduceinterfacetrapsandfi

8、xedcharges.tt0.44tsiox51022ox“dry-wet-dry-anneal”scheme-Besidesthermaloxidation,LPCVD/PECVDcandeposit-Siisconsumedinoxidationinaratioof0.44unitofSioxidefilmwithpoorerqualitythicknesstoform1unitofoxidethickness7/238/2322013-10-12BasicModelfo