Method for fabricating a bipolar transistor having self-aligned emitter and base

摘要

A method for forming a self-aligned bipolar transistor includes the steps of combination etching a silicon substrate (1) in an opening (5) to form a concave surface on the silicon substrate (1), and forming an intrinsic base (8) and an associated emitter (14) on the concave surface. The combination etching includes an isotropic etching and subsequent wet etching. The concave surface increases the distance between the external base (9) for the intrinsic base (8) and the emitter (14) to thereby increase the emitter-base breakdown voltage. <IMAGE>