Dopant diffusion control by adding carbon into Si and SiGe: principles anddevice application

The incorporation of low concentrations of carbon ( < 10(20) cm(-1)) into t he SiGe region of a heterojunction bipolar transistor (HBT) can significant ly suppress boron outdiffusion. caused by subsequent processing steps. This effect can be described by coupled diffusion of carbon atoms and Si point defects. We discuss the increase in performance and process margins in SiGe heterojunction bipolar technology by adding carbon. SiGe:C HBTs demonstrat e excellent static parameters, exceeding the performance of state-of-the-ar t SiGe HBTs. Carbon also enhances the high frequency performance, because i t allows one to use a high B doping level in a very thin SiGe base layer wi thout outdiffusion from SiGe, even if applying post-epitaxial implants and anneals. Finally, we demonstrate the first modular integration of SiGe:C HB Ts into a 0.25 mum, epi-free. dual-gate CMOS platform. (C) 2001 Elsevier Sc ience B.V. All rights reserved.