Effect of thermal nitridation on phosphorus diffusion in SiGe and SiGe:C and its implication on diffusion mechanisms

摘要

Complementary SiGe HBTs have many advantages over an NPN only technology for numerous analog applications requiring high speed, low noise, and large voltage swing [1,2], Controlling vertical doping profile is one of the most important approaches to enhance PNP heterojunction bipolar transistor (HBT) performance. Phosphorus (P) is used in PNP HBTs as the base layer dopant. Carbon (C) in SiGe base layers has been in use to reduce P diffusion. Thermal nitridation, which injects vacancies, may be an alternative approach to retard P diffusion. This work investigated the effectiveness of thermal nitridation in retarding P diffusion in SiGe and SiGe:C. It also provides an experimental study of P diffusion mechanisms in SiGe.