Patent ID: 8981430
Filing Date: 2015-03-17
Classification: H01L

Abstract:
1. A method of manufacturing a bipolar transistor, the method comprising: providing a semiconductor substrate as a collector; forming an intrinsic base on said semiconductor substrate; forming an extrinsic base on an outer portion of said intrinsic base, said extrinsic base having a first layer of a first semiconductor material; forming an emitter on an inner portion of said intrinsic base, said emitter being separated from said extrinsic base by one or more sets of spacers; forming a second layer of a second semiconductor material of said extrinsic base, said second semiconductor material having a smaller bandgap than that of said first semiconductor material; forming a first set of tunable non-conductive sidewall spacers defining edges of said extrinsic base away from said emitter and directly on said first semiconductor material; forming a recessed portion of said first semiconductor material such that a surface of said first semiconductor adjacent to said first set of tunable non-conductive sidewall spacers has an upper surface at a lower height than a surface under said first set of tunable non-conductive sidewall spacers; and forming said second semiconductor material directly on the upper surface of said recessed portion of said first semiconductor material.