Low temperature growth of poly-SiGe has been investigated by reactive thermal chemical vapor deposition method, which is a newly developed technique for preparing poly-SiGe by using redox reactions in a set of source materials, i.e., Si2H6 and GeF4. In order to prepare silicon-rich poly-SiGe of high mobility, a series of experiment on total pressure, gas flow rates of the source materials and dilution gas of He, and residence time at 450°C has been investigated.
At 0.45 Torr, high crystallinity films with high silicon content were prepared, however, homogeneity of film thickness and reproducibility of the film growth was quite low for device application. For overcoming this problem, the growth condition has been studied especially in higher-pressure range of 5-15 Torr. Appropriate choice of the residence time and the gas flow ratios lead to significant improvement in the Si content in the films. Finally, more than 95% of silicon-rich poly-SiGe films, which is p-type, has 7.5 cm2/Vs of Hall mobility and (220) orientation, have been prepared at 10 Torr and 450°C within ±2% fluctuation of reproducibility which is enough to fabricate devices.