Fluorine implant under isolation dielectric structures to improve bipolar transistor performance and matching

Abstract

A method of fabricating an integrated circuit including bipolar transistors that reduces the effects of transistor performance degradation and transistor mismatch caused by charging during plasma etch, and the integrated circuit so formed. A fluorine implant is performed at those locations at which isolation dielectric structures between base and emitter are to be formed, prior to formation of the isolation dielectric. The isolation dielectric structures may be formed by either shallow trench isolation, in which the fluorine implant is performed after trench etch, or LOCOS oxidation, in which the fluorine implant is performed prior to thermal oxidation. The fluorine implant may be normal to the device surface or at an angle from the normal. Completion of the integrated circuit is then carried out, including the use of relatively thick copper metallization requiring plasma etch.