Process to integrate fabrication of bipolar devices into a CMOS process flow

摘要

A BiCMOS method for forming bipolar junction transistors and CMOS devices in a substrate. To avoid erosion of the bipolar junction transistor material layers, gate spacers for the CMOS devices are formed while a bipolar junction transistor photoresist layer is in place. The photoresist layer is used for etching the emitter polysilicon layer (for single polysilicon layer bipolar junction transistors) or for etching the base polysilicon layer (for double polysilicon layer bipolar junction transistors) prior to gate spacer etch.