Reduced pressure-chemical vapor deposition of high Ge content Si1−xGex and high C content Si1−yCy layers for advanced metal oxide semiconductor transistors

We have studied in reduced pressure-chemical vapor deposition, the low-temperature growth kinetics of high Ge content Si1−xGex and high C content Si1−yCy layers on Si(0 0 1). The Ge concentration x dependence on the F(GeH4)/F(SiH2Cl2) mass flow ratio is well accounted for at 550 °C by x2/(1−x)=2.66F(GeH4)/F(SiH2Cl2). The associated SiGe growth rate linearly increases as the F(GeH4)/F(H2) mass flow ratio increases, from 0.15 nm min−1 (23% Ge) up to 3.9 nm min−1 (47% Ge). We have then quantified the macroscopic loading effects (i.e. the strong growth rate increase) that occur when switching from bulk, blanket to patterned, ultra-thin silicon-on-insulator (SOI) wafers. The Si1−xGex layers grown at 550 °C inside Si windows or on blanket wafers remain flat even for very high Ge contents (47%). Finally, through an important increase of the silane and methysilane partial pressures, we were able to obtain at 550 °C good quality, 15 nm thick Si1−yCy layers with substitutional C concentrations as high as 2.1%, with almost no interstitial C atoms (0.1% only). The dependence of the substitutional and of the total (i.e. substitutional+interstitial) C concentrations y on the F(SiCH6)/F(SiH4) mass flow ratio at 550 °C can satisfactorily be fitted using y/(1−y)=m (F(SiCH6)/F(SiH4)) relationships, with msubst.=0.64 and mtotal=0.78.