Patent ID: 9012291
Filing Date: 2015-04-21
Classification: H01L

Abstract:
1. A method of forming a bipolar transistor with an embedded epitaxial external base region, comprising at least the following steps: 3.1 forming a collector region of a first doping type; 3.2 forming a base region of a second doping type on the resulting structure of the step 3.1; 3.3 depositing a first dielectric layer on the base region; 3.4 opening a window in the first dielectric layer; 3.5 forming a polycrystalline layer of the first doping type and a second dielectric layer in sequence on the resulting structure of the step 3.4; 3.6 etching the second dielectric layer and the polycrystalline layer through photolithography to form an emitter, and removing exposed portions of the first dielectric layer; 3.7 depositing a third dielectric layer and forming a sidewall structure on a side surface of the resulting emitter structure through an anisotropic etching process; 3.8 etching portions of the base region that are not covered in the resulting structure of the step 3.7 by using the emitter and the sidewall structure as a mask, with an etching thickness being greater than a thickness of the base region; 3.9 forming an external base region of the second doping type on the resulting structure of the step 3.8 through an in-situ doping selective epitaxy process; 3.10 forming a layer of metal silicide structure on a surface of the external base region; and 3.11 forming a contact hole on the resulting structure of the step 3.10 to lead out an electrode of the emitter and an electrode of the base region.