Low temperature boron doping into crystalline silicon by boron-containing species generated in Cat-CVD apparatus

We have discovered that phosphorus (P) atoms can be doped into crystalline silicon (c-Si) at temperatures below 350°C or even at 80°C by using species generated by catalytic cracking reaction of phosphine (PH3) molecules with heated tungsten (W) catalyzer in Cat-CVD apparatus. As further investigation, here, we study the feasibility of low temperature doping of boron (B) atoms into c-Si by using decomposed species generated similarly from diborane (B2H6) molecules. Dependency of properties of doped layers on catalyzer temperature (Tcat) and substrate temperature (Ts) is studied by both the Van der Pauw method based on the Hall-effect measurements and secondary ion mass spectroscopy (SIMS) for B doping in addition to P doping. It is found that, similarly to P doping, the surface of n-type c-Si is converted to p-type even at Ts=80°C for Tcat over 800°C when c-Si is exposed to B2H6 cracked species for a few minutes, and that the heat of substrate over 300°C is likely to help for B doping contrary to P doping.