Patent ID: 6936519

Claim:
A method of manufacturing a bipolar transistor comprising: forming a substrate having a collector region; forming a base structure over the collector region; depositing a first polysilicon layer over the base structure; doping the first polysilicon layer to form an emitter polysilicon layer; depositing a thin dielectric layer over the emitter polysilicon layer; forming the emitter polysilicon layer to form an emitter structure having the thin dielectric layer over the emitter structure; forming a spacer around the emitter structure; depositing a second polysilicon layer over the emitter structure and the extrinsic base region; doping the second polysilicon layer to form a base polysilicon layer; planarizing the base polysilicon layer down to the first thin dielectric layer to remove the base polysilicon layer from over the emitter structure; forming the base polysilicon layer to form an extrinsic base structure over the collector region beside and spaced from the emitter structure by the spacer; depositing an interlayer dielectric layer over the substrate; and forming connections through the interlayer dielectric layer to the extrinsic base structure, the emitter structure, and the collector region.