International Business Machines Corporation
Extrinsic base doping for bipolar junction transistors

Abstract:

A device structure for a bipolar junction transistor includes a base layer made of a semiconductor material. An emitter is disposed on a first portion of the base layer. A dopant-containing layer is disposed on a second portion of the base layer. A hardmask is disposed on the base layer. The hardmask includes a window aligned with the second portion of the base layer. Deposits of the dopant-containing layer are limited to exposed surfaces of: the first portion that is disposed on a top surface of the base layer inside of the window.