Dielectric isolation bipolar transistor

摘要

The present invention relates to a method of forming deep trenches in a BICMOS-type integrated circuit wherein the formation of a bipolar transistor includes the steps of depositing a base polysilicon layer, depositing a protection oxide layer, forming an emitter-base opening, and etching the silicon oxide protection layer and the base polysilicon layer outside the bipolar transistor areas. The formation of the trenches includes the steps of opening the protection oxide and base polysilicon layers above a thick oxide region while the emitter-base opening is being made, etching the thick oxide layer while the protection oxide layer is being etched, and etching the silicon under the thick oxide while the base polysilicon is being etched.