Very-Low-Temperature Silicon Epitaxy by Plasma-CVD Using SiH4-PH3-H2 Reactants for Bipolar Devices

A novel plasma-CVD process has been developed for growing specular silicon epitaxial layers at very low temperatures of approximately 200°C. The epitaxial layers were deposited from SiH4-PH3 gases diluted with H2 on single-crystal substrates just after being etched in a HF dip. The highest electron mobility and lowest resistivity of the n+-layers were 30 cm2/V ·s and 4×10-4 Ω·cm, respectively. This technology has been successfully applied to fabricate bipolar transistors with a high current gain of 370.