ABSTRACT
Insemiconductormanufacturing,thesequentialchemicalHF+SC1+SC2recipeis conventionallyusedforpre-gatecleaning.Thecleaningsequenceisdesignedto removebulkSi02onSisubstratebyhydrofluoricacid(HF),followedbyparticulateremovalwithSCl(mixtureofDIwater,NH40HandH20 2),thenmetalsremovalwithSC2(mixtureofDIwater,HClandH20 2),andfinalIPAvapordrying.AnintermediateDIwaterrinseisusedbetweeneachchemicalstep.Inthe cleaning,ahydrophobicSisurfaceisproducedaftertheSi02isremovedcompletelybyHF.Thehydrophobicsurfacecaneasilyattractparticlesandcanalso beeasilyroughedordamagedbythefollowingSCIcleaning.WhileSCIcleans theSisurface,italsogrowsathinSi02layeronthesurface.Contaminants areeasilytrappedattheSiOrSiinterface,aswellaswithintheSi02layer.Any
defectsduetoparticulateandmetalliccontaminantsandsurfacedamagesatthe SiOrSiinterfacecanpotentiallyreduceproductionyieldbyshortingtheelectric devicesbuiltonthewafers.
