A method of fabricating a semiconductor uses chemical vapor deposition, or plasma-enhanced chemical vapor deposition, to deposit an amorphous silicon film on an exposed surface of a substrate, such as ASIC wafer. The amorphous silicon film is doped with nitrogen to reduce the conductivity of the film and/or to augment the breakdown voltage of the film. Nitrogen gas, N.sub.2, is activated or ionized in a reactor before it is deposited on the substrate.