Process for making a bipolar junction transistor with a self-aligned base contact

Claim 1

A bipolar junction transistor comprising: a substrate including a lightly doped base region and a collector region, a thick field oxide region covering a portion of said collector region, an emitter located on the substrate in electrical communication with the base region, a dielectric spacer structure covering said emitter and a portion of said base region located near said emitter, a thin base oxide layer contiguous with said field oxide region and covering a portion of said base region located away from said emitter, wherein said base oxide layer extends toward said dielectric spacer structure so as to leave an opening between said dielectric spacer structure and said base oxide layer, a heavily doped base contact region formed in said base region of said substrate in said opening between said dielectric spacer structure and said dielectric layer, a base interconnect link connecting to said base contact region through said opening and formed in part over said dielectric spacer structure, wherein said base interconnect link covers said opening, said base oxide layer, a portion of said field oxide region and a portion of said dielectric spacer structure so as to increase an area of access to said heavily doped base contact, and a metallic contact which contacts said base interconnect link.