Effect of H2 on Low Temperature Selective Growth of Si1-xGex by UHV/CVD
H2对UHV/CVD低温选择性外延生长Si1-xGex的影响

The selective epitaxial growth (SEG) of Si1-xGex is successfully achieved at a very low temperature by UHV/CVD.The effect and associated mechanism of H2 on the SEG are also investigated.The selective epitaxial growth of Si1-xGex is performed on Si wafers with 6mm×6mm patterns using SiH4 and GeH4 as gas sources.First,Ge sources without H2(pure GeH4) and with H2 (90% H2 diluted GeH4) are used in the growth process.According to the SEM images of the SiO2 substrate under two different conditions,H2 is vital in SEG.Then,using 90% H2 diluted GeH4 as the Ge source with varying the flow ratio of SiH4 and GeH4 (90% H2) in order to control the H2 partial pressure,the optimal flow ratio is obtained.The morphology of the samples,which are epitaxially grown for 40min at different flow ratios,are investigated by SEM.Finally,the SEM images are compared to those of samples grown under different gas sources, and the mechanism responsible for the effect of H2 in the SEG of Si1-xGex is analyzed.