Patent ID: 7932145

Claim:
A method of forming a bipolar transistor, the method comprising: forming a first dielectric layer over a semiconductor substrate; forming a base electrode for the bipolar transistor over the first dielectric layer; forming an oxide nitride structure over the base electrode; forming a first spacer with a first surface and a second surface opposite first surface and such that the first spacer is adjacent to the oxide nitride structure and the base electrode and the second surface is adjacent to the first dielectric layer; removing a top layer of the oxide nitride structure such that a first surface of the remaining oxide nitride structure is substantially planar with the first surface of the first spacer; removing a first portion of the first dielectric layer; forming an epitaxial layer over the semiconductor substrate; forming a second spacer over the epitaxial layer; and forming an emitter electrode over the epitaxial layer and adjacent to the second spacer; wherein: removing the top layer of the oxide nitride structure and removing a first portion of the first dielectric layer occur simultaneously with each other and occur after forming the first spacer.