A Simple Method to Control Bipolar Polysilicon Emitter Interfacial Oxide

Abstract

Polysilicon emitters are prevalent in today's advanced BiCMOS processes. Electrical and materials analysis have been used to demonstrate the increase in npn current gain, for polysilicon emitters, with an increasing interfacial "oxide" thickness. This interfacial "oxide" thickness has been tailored by the polysilicon push temperature into an LPCVD vertical thermal reactor. The interfacial "oxide" thickness has been shown to affect the npn current gain by modulating the base current without significantly impacting the collector current.