System and method for providing a self aligned bipolar transistor using a sacrificial polysilicon external base

摘要

A system and method are disclosed for providing a self aligned bipolar transistor using a sacrificial polysilicon external base. An active region of a transistor is formed and a sacrificial polysilicon external base is formed above the active region of the transistor and covered with a silicon oxide layer. Then an emitter window is etched and filled with silicon nitride. An etch procedure is subsequently performed to remove the sacrificial polysilicon external base. A layer of doped polysilicon material is then deposited to fill a cavity within the transistor formed by the removal of the sacrificial polysilicon external base. A polysilicon emitter structure is subsequently formed in the emitter window. The self aligned bipolar transistor architecture of the invention is compatible with BiCMOS technology.