Patent ID: 7816221
Filing Date: 2010-10-19
Classification: H01L

Abstract:
1. A method for forming a semiconductor device, comprising: providing a semiconductor substrate having therein a collector region extending to an upper surface of the semiconductor substrate; forming a multi layer dielectric on or above the upper surface; forming an extrinsic base contact above the multi layer dielectric; providing a trench extending through the extrinsic base contact and the multi layer dielectric to the upper surface; etching a lateral cavity in an upper part of the multi layer dielectric adjacent the trench and extending past an end of the extrinsic base contact, leaving in place a lower part of the multi layer dielectric separating the lateral cavity from the collector region; and forming an intrinsic base region over the semiconductor substrate in the trench and filling the lateral cavity with a semiconductor transition region coupling the intrinsic base region and the extrinsic base contact, and separated from the collector region by the lower part of the multi layer dielectric.