Physics, technology, and modeling of polysilicon emitter contacts for VLSI bipolar transistors

The physics of minority-carrier injection into polysilicon-contacted emitters is studied through a series of experiments correlating the structure of the polysilicon/monosilicon interface to the base current of the devices. An analysis of the results obtained indicates that only very low values of base current can be obtained without resorting to the use of intentionally grown chemical oxides. For devices etched in HF prior to polysilicon deposition, the base current is mainly determined by the recombination and blocking of minority carriers at the polysilicon/monosilicon interface.