A Nonrecessed-Base, Self-Aligned Bipolar Structure with Selectively Deposited Polysilicon Emitter

A new self-aligned bipolar structure, which fea- tures a nonrecessed base and a selectively deposited polysilicon emitter, is proposed. The in situ surface cleaning process prior to the selective-polysilicon deposition minimizes the residual native oxide in the emitter window. Both high-quality selective-polysilicon film and well-behaved submicrometer bipolar device characteristics have been obtained for bipolar or BiCMOS VLSI applications. The impacts of the nonrecessed-base device structure on the bipolar device parameter distribution and bipolar hot-carrier immunity have also been discussed.