Method of forming extrinsic base by diffusion from polysilicon/silicide source and emitter by lithography

摘要

PCT No. PCT/JP85/00432 Sec. 371 Date Apr. 9, 1986 Sec. 102(e) Date Apr. 9, 1986 PCT Filed Jul. 31, 1985 PCT Pub. No. WO86/01338 PCT Pub. Date Feb. 27, 1986.This invention relates to a method of producing a semiconductor device which is suitable for forming a bipolar transistor having less fluctuation of characteristics at a high production yield. In accordance with the present invention, a graft base (or an extrinsic base) 20 is formed by doping an impurity from a polycrystalline silicon film 13, while an emitter is formed by lithographic technique. Since the emitter is formed by lithographic technique, the position at which the emitter is to be formed unavoidably changes at the time of mask alignment, but its influence upon transistor characteristics is negligible. Therefore, bipolar transistors having far more uniform characteristics can be formed far more easily than with the method which forms the emitter by self-alignment.