Patent ID: 6884689

Claim:
A method for fabricating a bipolar transistor, comprising the steps of: providing a substrate having an epitaxial layer already formed thereon, wherein the epitaxial layer serves as a base; forming sequentially a first dielectric layer, a second dielectric layer on the epitaxial layer; forming an opening in the second dielectric layer; forming a conductive spacer on a sidewall of the opening; removing the first dielectric layer within the opening using the second dielectric layer and the conductive spacer as a mask; forming a conductive layer in the opening; removing the conductive layer outside the opening to form an emitter; removing the second dielectric layer and a portion of the first dielectric layer to form a self-aligned bipolar transistor using the emitter and the conductive spacer as a mask; and performing a doping step on the epitaxial layer to form an extrinsic epitaxial base contact area.