Patent ID: 7157786

Claim:
A bipolar junction transistor comprising: a doping region of a first conductivity type; a plurality of isolated structures positioned on both ends of the doping region; a base electrode structure formed on portions of the doping region, comprising: a protection layer formed on portions of the doping region; a doping layer of a second conductivity type formed on the protection layer and portions of the doping region; a first silicide layer formed on portions of the doping layer to be a base contact region of the bipolar junction transistor; a collector electrode structure formed on portions of the doping layer, comprising: a first polysilicon layer formed on the doping layer; a second silicide layer formed on the first polysilicon layer to be a collector contact region of the bipolar junction transistor; an emitter electrode structure formed on portions of the doping region, comprising: a second polysilicon layer formed on the doping region; a third silicide layer formed on the second polysilicon layer to be a collector contact region of the bipolar junction transistor; and a spacer structure located between sidewalls of the base electrode structure, the collector electrode structure and the emitter electrode structure for isolation.