Patent ID: 9099397
Filing Date: 2015-08-04
Classification: H01L

Abstract:
1. A method of forming a self aligned base contact for a transistor, the method comprising: forming a collector layer on a substrate; forming a base layer on the collector layer; forming an emitter layer on the base layer; forming a first metal on a first emitter area of the emitter layer of the transistor; forming a second metal on a second emitter area of the emitter layer of the transistor, wherein the first metal and the second metal are not in direct physical contact; etching the emitter layer to remove the emitter layer surrounding the first emitter area, wherein the first emitter area is masked by the first metal, and to remove the emitter layer surrounding the second emitter area, wherein the second emitter area is masked by the second metal, so that the base layer is exposed surrounding the first emitter area and the second emitter area; and depositing base metal on the base layer, on the second metal, over sides of the second metal, and over sides of the second emitter area, so that the base metal on the base layer, the base metal on the second metal, the base metal over sides of the second metal, and the base metal over sides of the second emitter area are in contact with each other; wherein the first emitter area is an emitter of the transistor and the first metal provides an emitter contact; and wherein the base metal provides a base contact; and wherein the base metal is not in direct physical contact with the first metal or the first emitter area.