Method for forming a self-aligned bipolar junction transistor with

Abstract

In a method of fabricating a self-aligned bipolar junction transistor with silicide extrinsic base contacts and selective epitaxial grown intrinsic base region, the sinker and buried N+ layer regions are formed in a semiconductor substrate with trench oxide isolation. Thin oxide is then formed on the structure. Next, metal silicide is deposited on the thin oxide and p-dopant implanted into the silicide. LTO is then deposited on the doped silicide followed by deposition of nitride. Next, the nitride, LTO and silicide layers are etched, stopping on the thin oxide layer. The thin oxide is then etched to expose the silicon. The etch undercuts the thin oxide under the nitride. A thin p+ epitaxial base is then selectively grown on the silicon and the metal silicide only. The base can be silicon or a silicon germanium layer to form a heterojunction transistor. Next, thin LTO is deposited followed by deposition of nitride. An RIE of the nitride is then performed to form nitride spacers, stopping on the thin LTO. The thin LTO is then wet etched to open the epitaxial base. A n-type, low-doped, selective single crystalline silicon emitter is then grown. This is followed by deposition of polysilicon and an n-dopant implant into the polysilicon. The polysilicon is then masked and etched to define a n+ polysilicon region in contact with the n-type single crystalline emitter. Next, a layer of oxide is deposited, followed by a furnace drive and rapid thermal anneal activation step for the base and emitter. Base, emitter and collector vias are opened and a metallization layer is formed and patterned to provide base, emitter and collector contacts.