Patent ID: 6949438

Claim:
A method of fabricating a bipolar junction transistor, the method comprising: providing a substrate, the substrate comprising a plurality of isolation structures for defining at least an active area; implanting ions of a first conductive type into the substrate to form a doping region in the active area; forming a protective layer on the substrate, the protective layer comprising an opening to expose the doping region; forming an epitaxial layer of a second conductive type and a dielectric layer on the substrate; removing a portion of the dielectric layer in the active area down to a surface of the epitaxial layer; forming a semiconductor layer of a first conductive type on the substrate; removing a portion of the semiconductor layer outside the active area to form a second doping layer on the doping region; removing the entire dielectric layer; and removing a portion of the epitaxial layer to form a first doping layer on the doping region.