Integration of an NPN device with phosphorus emitter and controlled emitter-base junction depth in a BiCMOS process

摘要

According to one exemplary embodiment, a heterojunction bipolar transistor includes a base situated on a substrate. The heterojunction bipolar transistor can be an NPN silicon-germanium heterojunction bipolar transistor, for example. The heterojunction bipolar transistor further includes a cap layer situated on the base, where the cap layer includes a barrier region. The barrier region can comprises carbon and has a thickness, where the thickness of the barrier region determines a depth of an emitter-junction of the heterojunction bipolar transistor. An increase in the thickness of the barrier region can cause a decrease in the depth of the emitter-base junction. According to this exemplary embodiment, the heterojunction bipolar transistor further includes an emitter situated over the cap layer, where the emitter comprises an emitter dopant, which can be phosphorus. A diffusion retardant in the barrier region of the cap layer impedes diffusion of the emitter dopant.

主权项

1. A heterojunction bipolar transistor comprising:
a base situated over a collector, said collector being situated in a substrate; a cap layer situated on said base, a portion of said cap layer comprising a concentration of a diffusion retardant; an emitter situated over and in contact with said portion of said cap layer, said emitter comprising an emitter dopant; wherein said diffusion retardant impedes diffusion of said emitter dopant, and wherein a depth of an emitter-base junction of said heterojunction bipolar transistor is controlled by determining said concentration of said diffusion retardant in said portion of said cap layer such that said diffusion retardant in said cap layer is concentrated adjacent said emitter.