Method for selectively doping the intrinsic collector of an epitaxial base vertical bipolar transistor

摘要

Selective doping of the intrinsic collector of a vertical bipolar transistor comprises high energy dopant implantation before epitaxy and lower energy and lower dose dopant implantation after epitaxy of a silicon germanium heterojunction base. Selective doping of the intrinsic collector of a vertical bipolar transistor is carried out by (a) forming the intrinsic collector (4) on an extrinsic collector layer buried in a semiconductor substrate; (b) forming a lateral insulation region (5) around the upper part of the intrinsic collector and an offset extrinsic collector well; (c) effecting a first dopant implantation in the intrinsic collector through a first implantation window above the intrinsic collector; (d) forming a silicon germanium heterojunction base above the intrinsic collector (4) and the lateral insulation region (5) by non-selective epitaxy of a silicon and silicon germanium multilayer (8); and (e) effecting a second lower energy and lower dose dopant implantation in the intrinsic collector across the multilayer in a second implantation window located within the first implantation window above the multilayer (8) and self-aligned with the emitter.