RAPID THERMAL CHEMICAL-VAPOR-DEPOSITION OF IN-SITU BORON-DOPED POLYCRYSTALLINE SILICON-GERMANIUM FILMS ON SILICON DIOXIDE FOR COMPLIMENTARY-METAL-OXIDE-SEMICONDUCTOR APPLICATIONS

In situ boron-doped polycrystalline Si1-xGex (x>0.4) films have been f ormed on the thermally grown oxides in a rapid thermal chemical vapor deposition processor using SiH4-GeH4-B2H6-H-2 gas system. Our results showed that in situ boron-doped Si1-xGex films can be directly deposit ed on the oxide surface, in contrast to the rapid thermal deposition o f undoped silicon-germanium (Si1-xGex) films on oxides which is a part ially selective process and requires a thin silicon film pre-depositio n to form a continuous film. For the in situ boron-doped Si1-xGex film s, we observed that with the increase of the germane percentage in the gas source, the Ge content and the deposition rate of the him are inc reased, while its resistivity is decreased down to 0.66 m Omega cm for a Ge content of 73%. Capacitance-voltage characteristics of p-type me tal-oxide-semiconductor capacitors with p(+)-Si1-xGex gates showed neg ligible polydepletion effect fur a 75 Angstrom gate oxide, indicating that a high doping level of boron at the poly-Si1-xGex/oxide interface was achieved. (C) 1997 American Institute of Physics.