Patent ID: 8946041
Filing Date: 2015-02-03
Classification: H01L

Abstract:
1. A method for forming a bipolar transistor, comprising: providing a semiconductor substrate having a first surface, then in any order; forming in the semiconductor substrate a collector having a first region underlying and separated from the first surface and a second region extending from the first region toward the first surface; forming in the substrate a base having a first region of a first base depth from the first surface and a second region of a second base depth from the first surface larger than the first base depth, and wherein the base region has portions of varying lateral base widths underlying an emitter region, wherein a lateral base width is a dimension perpendicular to an upper surface of the bipolar transistor; and forming in the substrate the emitter having a first emitter region of a first emitter depth from the first surface and a second emitter region of a second emitter depth from the first surface larger than the first emitter depth.