US Patent 11935928 Bipolar transistor with self-aligned asymmetric spacer

The present disclosure relates to semiconductor structures and, more particularly, to a bipolar transistor with self-aligned asymmetric spacer and methods of manufacture. The structure includes: a base formed on a semiconductor substrate; an asymmetrical spacer surrounding the base; an emitter on a first side of the base and separated from the base by the asymmetrical spacer; and a collector on a second side of the base and separated from the base by the asymmetrical spacer.