Transistor having emitter self-aligned with an extrinsic base contact and method of making it.

摘要

A vertical bipolar transistor structure has an extrinsic base region (4) covered by a metal silicide (eg WSi2) layer (6) and a doped (eg with boron) polysilicon layer (7). The metal silicide and polysilicon layers (6, 7) have an opening therein with which the emitter (3) and intrinsic base region (2) of the transistor are aligned.
The vertical bipolar transistor structure can be produced by a method including delimiting a transistor area in a semiconductor substrate, depositing in succession over the the transistor area a silicide layer (6), a doped polysilicon layer (7) and a silicon dioxide layer (8), forming an aperture through the silicon dioxide, the doped polysilicon and the silicide layers, forming an insulating layer (8A) over the transistor area and driving in dopant from the polysilicon layer to form an extrinsic base region (4), removing the insulating layer from the base of the aperture but not from the sidewall of the aperture and forming an intrinsic base region and an emitter aligned with the aperture and the extrinsic base region.