螯合剂在微电子工艺中减少硅表面重金属污染的应用研究

河北工业大学博士学位论文螯合剂在微电子工艺中减少硅表面重金属污染的应用研究姓名：张西慧申请学位级别：博士专业：微电子学与固体电子学指导教师：刘玉岭20070401FA/OCuIIFeIIIFA/OFA/OpH10pH12FA/OCuIIFeIIIlogK9.6918.7FA/ODHFRCAFA/ONH4OH/H2O2/H2OSC1EDTAFA/OFA/OSC1NH4OHCuDHFDHFDHFPAAAPPLICATIONSTUDYOFSOMECHELATINGAGENTSFORREDUCINGCOPPERCONTAMINATIONONSILICONWAFERSURFACEINMICROELECTRONICSPROCESSABSTRACTAlongwiththecharacteristicsizereducingandtheintegrationrapidlyenhancementinULSIthemetalimpuritiesharmappearsspeciallyprominently.Therequestformetaltarnishonsiliconsubstratesurfacewillbeslowerandslower,butthemetaltarnishisnearlyinevitable.Thispaperproceededwiththeinevitablecontactandreactionbetwwensiliconandsomekindsofaqueoussolutionusedinmicroelectroniccraft.Themethodhereisaddingchelatingagentinsolutions.Ontheonehand,itcanreducemetaldepositonopportunityasfaraspossible;ontheotherhanditcaneliminatethealreadymetalpollutionasfaraspossible.ThestabilityconstantsofCu(II)andFe(III)withtheFA/Ochelatingagentwerefirstdetermined,whichwasinventedbyProfessorLiuYulinginHebeiuniversityoftechnology.TheresultsshowedthattheFA/Ochelatingagenthasatleasttencoordinatingatoms;theFA/OchelatingagentsuitsforusinginalkalinesolutionwithpH10prefentiallypH12.ThechelatestabilityconstantslogKofCu(II)andFe(III)withFA/Oare9.69and18.7respectively.Withcopperastheexample,thereducingeffectofCucontaminationwasalsodeterminedinthispaperforFA/OchelatingagentandotherkindsofchelatingagentsinDHFcleaningsolution,theRCAcleaningsolutionaswellasthepolishingslurryofsiliconsubstrate.ThecopperconcentrationonsiliconsurfacewasdeterminedbyGFAASjointwithone-dropsandwichetchingmethod.InthealkalineSC1cleaningsolution(NH4OH/H2O2/H2O)andthealkalinepolishingslurry,theresultsindicatedthatFA/OwasbetterthanthetraditionalchelatingagentEDTAwithreductionofcopperpollutiononsiliconwafersurface.Moreover,comparedwithEDTA,FA/Ohasotheradvantages:notcontainingNa+,easilysolubleinwater,convenienttouseandsoon.WhenNH4OHinSC1cleaningsolutionwassubstitutedbyFA/O,copperconcentrationonsiliconwafercouldmeettherequestofmicroelectronicprocessonlybyonestepclean.TheCucontaminationreducingeffectsofseveralkindsofacidicchelatingagentwerealsostudiedinDHFcleaningsolutionandtheacidicpolishingslurry.AddingchelatingagentinDHFcleaningsolutiontoreducemetaldepositiononthesiliconsurfacewasfirstproposedbyauthor.ThedatashowedthatphosphonicacidchelatingagentDTPMPwasbetterinDHFsolutionandcarboxylicacidchelatingagentPAAwasbetterinacidicpolishingslurry.Themetalpollutionreducingmechanismofdifferentchelatingagentwasalsoanalysizedinthispaper.TheeffectofchelatingagentsonreducingCucontaminationonsiliconwafersurfacewascarriedoutbytwoways:reducingfreemetallicionsinthesolutionbycoordinatingequillirmandreducingadsorptionopportunitiesonsiliconsurfaceofmetalionsbycompetitiveadsorption.Whenthechelatingagentwaslargeinpolarityandlargeinsize,itwouldpreferentiallyadsorpedonsiliconsurfaceandtheadsorptionwaycouldbetheleadingrole.KEYWORDS:chelatingagent,microelectronics,coppercontamination,deposition,cleaningcompetitiveadsorption1195820601G100.25µmCMOS65nmCMOS[1~3][4]6045ppbNaKLiCuFeNiAgCr[5~10][11~13]1010atom/cm2[2,14~15]§1-11-1-116.7%1.12eV2002000SIA2IC85%2121[16]1.1图1.1硅片表面层吸附力场来源示意图Figure1.1Theadsorptionforceonthesurfaceofsiliconwafer1.2[10]1.2a1.2b图1.2硅片表面原子具有悬空键（a—体相的硅原子，b—表面相的硅原子）[10]Figure1.2Thestringbandofatomsonsiliconwafersurface(a—atomsinsilicon,b—atomsonsurface)3[17][18-20]1.4图1.4硅片表面污染物示意图Figure1.4ThecontaminatantsonsiliconwafersurfaceNaClFIHF[21]1.51.5a1.5b1.5c图1.5硅晶片表面沾污物的物理位置示意图[22]（a—在裸露的硅表面，b—在覆盖有氧化物的表面上，c—镶嵌于表面氧化物中）Figure1.5ThephysicalstateofcontaminantsonsiliconwafersurfaceCu4AlCrFe1-1-2IC,1-1-2-1[23,24]表1.1微电子技术用的主要气体种类[25]Table1.1thetypeofmaingasusingformicro-electronicstechnologyO2H2HClCl2N2p-nPH3POCl3B2H6BCl3AsH3AsCl3O2N2PH3PF3BCl3BF3AsH3O2SiF4A1ArN2FCF4SF6NF3SiF4BF3CBrF3XeF2Cl-FCClF3CCl2F2CCl3FC2ClF5C2Cl2F4SiBrHBrBr2F-HCHF3CF4-H2SiO2F/C4C2F6C3F8C4F3ClCCl4BCl3SiCl4Cl2HClCCl2F2CCl3FA1BrBr2BBr3CVDSiO2BPSGSiH4+O2SiH4+O2+PH3+B2H6CVDSi3N4SiO2SiH4SiH4+PH3SiH4+NH3SiH2Cl2+NH3SiH4+N2OSiO2SiH4+N2O5CVDSi3N4SiH4+O2SiH4+NH3SiH4+N21-1-2-21.110-9FeCu[26]1-1-2-3180110012SiCWeberRiotte[27]DeBusk[28]O2Schmidt[29,30]SiC1150Schmidt[31]HCl3[32][33]4ppm70~200ppb10ppb4Hattori[34]Sigiura[35]1012~1013cm-21013cm-261012cm-2[36,37,38]51-1-2-41.2EMerck表1.2EMerck公司生产的常用清洗试剂[25]Table1.2theusualcleaningreagentproducedbyEMerckcompany(max)10-6CaFeMgNa95%~97%LSIVLSI0.20.10.20.10.10.050.50.237.5%1.0%LSIVLSI0.50.20.20.10.10.050.50.269.4%0.5%LSIVLSI0.10.10.20.10.10.050.30.328%LSIVLSI0.20.10.10.050.10.050.50.230%LSIVLSI0.10.10.10.050.050.050.10.199.5%LSIVLSI0.50.10.10.010.10.020.50.185%LSIVLSI2020101055101099.8%LSIVLSI0.50.10.10.050.10.020.50.149.5%1.0%LSIVLSI10.50.50.10.20.050.20.11-1-2-5,,256KbDRAM64Kb1.4,1Mb64Kb1.7300-50030[59],1.3TI710-10[39]1.4/表1.3美国TI公司满足4MDRAM生产要求的水质[25]Table1.3thewaterquantityofTICompanyinAmericameetstheproducerequirementsof4MDRAM(25M.cm)18.0(/ml)0.01Do(x10-9)50TOC(x10-9)20(0.1m/mL)0.03(0.05m/mL)0.03(x10-9)5(LiNaK……x10-9)0.05(NH4+Cl-Br-NO3SO3SO42-PO4-3x10-9)0.05表1.4圆片清洗工艺中所用的化学试剂[39]Tabl