用BP做緩沖層在Si(001)襯底上外延生長SiC

用BP做緩沖層在Si(001)襯底上外延生長SiC報(bào)告人:張中偉材料科學(xué)與工程系2005年12月20日SiC的特性禁帶寬度大

擊穿電壓高

熱導(dǎo)率高(變形系數(shù)α/λ小)電子遷移率高

抗輻射能力強(qiáng)、化學(xué)穩(wěn)定性好等優(yōu)良特性機(jī)械性能好(耐磨)

能隙/eV遷移率/(cm2/Vs)介電常數(shù)熱導(dǎo)率/W/cmK)ΒSiC(3C)2.35>8009.74.9ΑSiC(6H)2.86<400>9.74.9Si1.12138011.81.5GaAs1.43850012.80.5Tab.1SiC與其他幾種半導(dǎo)體性能比較Si襯底外延生長3C-SiC存在的問題錯(cuò)配度很大Si:as=0.543nm3C-SiC:ae=0.435nmBP:a=0.454nm(與3C-SiC相近)Fig.1.LPCVD示意圖用BP做緩沖層在Si(001)襯底上外延生長SiCSi(001)在LPCVD中1000℃下6minBP薄膜生長(850--900℃)B2H6+PH3B2H6flowrate:1.5sccmP/B比=125SiH45.0sccmSiH4+C3H8SiH43.3sccm在BP上生長Si薄膜(10nm)降溫500℃以下C3H840sccm快速升溫100℃/minSi炭化生成SiC1150℃3C-SiC生長850℃Fig.2.GrowthconditionsunderwhichSifilmsweregrownon

aBPlayerinoursystem.

結(jié)果討論Fig.1:

Cross-sectionalTEMmicrographs

(a)BPfilmgrownonSi(b)SiCfilmgrownonSiSiC/BP/Si結(jié)晶質(zhì)量Fig.2:Aθ/2θscanXRDofthethinSiCsampleswithandwithouttheBPbufferlayer

BPfilm的厚度對3C-SiC表面粗糙度的影響Fig.3:AFManalysisoftheBPfilms(right)andSiC1μmthickfilms(left)grownontheirBPfilms,thethicknessesofwhichare150nm(above)and400nm(below).

有緩沖層生長的SiC與沒有緩沖層生長的SiC缺陷密度比較Fig.4:Cross-sectionalTEMmicrographsof4μmthickfilmsgrownonSi(001)withtheBPfilm(left)andwithouttheBPfilm(right)Fig.5:AFManalysisofa4mmthickSiCfilmandacorrespondingsmallerselectedareaview

ConclusionBPfilm能有效地緩解Si與3C-SiC之間的晶格錯(cuò)配,有BP薄膜做緩沖層生長的3C-SiC缺陷濃度比沒有BP的低.BP薄膜表面隨著厚度的增加變粗糙,最佳厚度為150nm.3C-SiC表面平整度