2024年4月11日发(作者：)

第

44

卷第

7

期

2015

年

7

月

人工晶体学报

JOUＲNALOFSYNTHETICCＲYSTALS

Vol．44No．7

2015

July，

ChemicalMechanicalPolishingof4H-SiC

withStrongOxidizingSlurry

2

LIANGQing-rui

1，

，HUXiao-bo

1

，CHENXiu-fang

1

，XUXian-gang

1

，ZONGYan-min

2

，WANGXi-jie

2

（1．StateKeyLaboratoryofCrystalMaterials，ShandongUniversity，Jinan250100，China；2．SICCMaterialsCo．，Ltd，Jinan250111，China）

（Ｒeceived10February2015，accepted15March2015）

Abstract：Anovelchemicalmechanicalplanarization（CMP）techniquewasdemonstratedusinghybrid

polishingliquidwhichwascomposedofstrongoxidizerabrasiveslurry（SOAS）withKMnO

4

．After

doublefacepolishingwithdifferentmassconcentrationsofKMnO

4

，4H-SiCsubstrateswereassessed．

Surfaceroughnessandwaferremovalrateweremeasuredbyatomicforcemicroscopy（AFM）and

precisionscale，respectively．TheresultsshowthattheSOASwithappropriateKMnO

4

concentrationcan

greatlyraisethematerialremovalrate（MＲＲ）andimprovethesurfacequalityof4H-SiCsubstrate．

Keywords：SiC；CMP；KMnO

4

；roughness；removerate

CLCnumber：TN305．2Documentcode：AArticleID：1000-985X（2015）07-1741-07

DOI:10.16553/1000-985x.2015.07.005

4H-SiC

的强氧化液化学机械抛光

1，211122

胡小波

，

陈秀芳

，

徐现刚

，

宗艳民

，

王希杰梁庆瑞

，

（1．

山东大学晶体材料国家重点实验室

，

济南

250100；2．

山东天岳晶体材料有限公司

，

济南

250111）

摘要

：

研究了一种新型的化学机械抛光方法

，

使用以

KMnO

4

作为氧化剂的强氧化性化学机械抛光液

（SOAS）

进行

SiC

硅面和碳面的化学机械抛光过程中

，SOAS

溶液中

KMnO

4

的浓度对抛光质量的影

化学机械抛光

。

研究了在

4H-

响

。

使用原子力显微镜

（AFM）

和精密电子天平

，

分别测试了表面粗糙度和去除率

。

结果表明

，

适量的

KMnO

4

可以

SiC

的化学机械抛光去除率

，SiC

衬底的表面抛光质量

。

同时可提高

4H-

大幅度提高

4H-

关键词

：

碳化硅

；

化学机械抛光

；

高锰酸钾

；

粗糙度

；

去除率

1Introduction

SiCbelongstothethirdgenerationsemiconductormaterial，whichhasawiderangeofapplicationsinthefields

ofoptoelectronicandhighpowersemiconductordevicesbecauseofitsoutstandingcharacteristics，suchasexcellent

mechanicalproperties，verywidebandgap，highthermalconductivity，highcarriermobility，etc

［1-4］

．Commercial

SiCsubstraterequiresadefect-freesurface．ForSiCsinglecrystalsubstrate，therearetwomainkindsofdefects．

Oneisgrown-indefectssuchasmicropipes，dislocations．Theotherispost-growthdefectscausedbypost

treatment，forinstance，scratches，pitsandbumps．CMPisakindofglobalplanarizationpolishingprocess

6］

．BeforeCMPprocess，therearemanydamagesonthe

especiallyforthepolishingofhardandbrittlematerials

［5，

Ｒeceiveddate：2015-02-10；accepteddate：2015-03-15

Foundationitem：NationalBasicＲesearchProgramofChina（2011CB301904）

；Natural

ScienceFoundationofChina（11134006，51321091）

Biography：LIANGQing-rui（1989-），Male，fromShandongProvince，DoctorGraduate．E-mail：liangqingrui@126．com

Correspondingauthor：HUXiao-bo，Professor．E-mail：xbhu@sdu．edu．cn

1742

人工

晶体学报第

44

卷

surfaceofSiCsubstratesproducedbysawing，lapping，andmechanicalpolishingprocessforsurfacepreparation．

ThebasicprincipleofCMPisthecombinationofmechanicalgrindingandchemicalreaction．Chemicaloxidation

occursatfirstonthewafersurface，andthenthesurfaceoxidelayerisremovedbymechanicalgrindingonasoft

abrasivepad．Highqualitysubstratesurfacecouldbeobtainedbythemutualactionofoxidationreactionand

mechanicalgrinding．However，thechemicalandmechanicalpropertiesofSiCgreatlyincreasethedifficultyof

CMPprocess

［7］

．

ForCMPprocessofSiCsinglecrystalsubstrate，theMＲＲandsurfaceroughnessarethemainevaluation

parameters．TheMＲＲpresentstheprocessingefficiencyandthesurfaceroughnessreflectstheprocessingquality．

Suetal．hadstudiedtheinfluencesofthepolishingslurrycompositionincludingthepHvalue，theabrasivesize

anditsconcentration，thedispersantandtheoxidants，aswellastherotationalspeedofthepolishingplatenandthe

polishingpressureontheMＲＲofSiCcrystalsubstrate（0001）Sisurface

［8］

．Theirresultsshowedthatthechemical

reactionrateincreasedwiththeraiseoftheoxidantcontents．Leeetal．usedthemixedabrasiveslurry（MAS）of

colloidalsilicaandnano-diamondforCMPofSiC

［9］

．ExperimentalresultsindicatedthattheMAScanachieve

higherMＲＲthancolloidalsilicaslurry．Chenetal．studiedtheCMPofdifferent6H-SiCcrystalfacesandfound

thattheMＲＲandsurfacequalityvariedgreatlywiththedifferentcrystalsurfaceorientations

［10］

．

Uptonow，theMＲＲofSiCmaterialisonlyabout100nm/hbyCMPwhichisinefficientforindustrialization．

AlthoughahighMＲＲofSiCmaterialcanbeachievedbydifferentmethods，itisveryhardtogetahigh-quality

surfaceatthesametime．ThepaperdemonstratedanovelCMPmethodusingmixedpolishingliquidwhichwas

aluminananoparticles．Afterthe4off-axis4H-SiC

composedofstrongoxidizerabrasiveslurrywithKMnO

4

and

α

-

waferswereCMPprocessedinthemixedpolishingliquid，ahigherremovalratewasachievedandasmoother

surfacewasobtained．

2Experimental

Then-type4°off-axis4inch4H-SiCsinglecrystalsweregrownbythesublimationmethod．Fig．1showsthe

AFMimageofSiCsurfacebeforeCMP．Thewaferswerepolishedbydiamondabrasiveslurryfromthegrinding

wafers．TherearemanyinterlacedscratchesonthesurfaceofSiCwafer，andtheroughnessis1．13nm．TheCMP

experimentswereconductedbyusingdifferentslurriesonaCMPmachine．Alltheexperimentsweredoneinaclean

roomwithGrade1000attheconstanttemperatureof22-25℃．TheMＲＲwasmeasuredbyweightlossmethod

usingaprecisionscale（±0．01mg）．BoththeroughnessandmorphologyofSiCsurfaceweremeasuredbyAFM．

The

α

-alumina（Al

2

O

3

）andalkaline-basedcolloidalsilicaslurrieswerepurchasedfromacommercialmarket，

whiletheSOASwasmadebymixingaluminaslurrywithKMnO

4

．ThePHofSOASwasadjustedbyHNO

3

．The

CMPwasconductedundertheconditionssummarizedinTable1．

Table1

Parameters

Platenrotationspeed/rad·min

－1

Carrierrotationspeed/rad·min

Appliedpressure/kg·cm

－2

Polishingpadtype

Slurrytype

Slurryflowrate/mL·min

－1

－1

Specificexperimentalconditions

Conditions

60

40

0．4

Felttypepad

Alumina（120nm，20wt%andpH3）

；

StrongSOASwith（0wt%，0．1wt%，0．3wt%，0．6wt%）KMnO

4

and

α

-

basedcolloidalsilicaslurry（120nm，20wt%，H

2

O

2

andpH12）

Alkaline-

120

3

3．1

ＲesultsandDiscussion

CMPresultsofSiC-Sifaceusingdifferentslurries