Patent ID: 7180157
Filing Date: 2007-02-20
Classification: H01L

Abstract:
1. A double-polysilicon, self-aligned bipolar transistor having a collector region formed in a doped semiconductor substrate, an intrinsic counterdoped base formed on the surface of the substrate and a doped emitter formed in the surface of the intrinsic counterdoped base, comprising: a first dielectric layer formed over a portion of the top surface of the intrinsic counterdoped base above the collector region in the substrate; a base contact layer of a conductive material formed on exposed surfaces of the first dielectric layer and the intrinsic counterdoped base aside from the first dielectric layer; a second dielectric layer formed over the base contact layer; a wide window extending through the first dielectric layer and the base contact layer stopping at the first dielectric layer; sidewall spacers formed on the sidewalls of thc wide window; a narrowing structure formed in the wide window; at least one narrowed window formed within the wide window juxtaposed with the narrowing structure; the narrowed window and the remainder of the wide window being filled with doped polysilicon comprising an extrinsic emitter; and an intrinsic emitter region formed below the extrinsic emitter in the surface of the intrinsic counterdoped base.