Suppression of boron outdiffusion in SiGe HBTs by carbon incorporation

A key problem faced by npn SiGe technology is the outdiffusion of boron from the SiGe base caused by thermal annealing or transient enhanced diffusion. In this paper we investigate the effects of C incorporation in the base on boron diffusion caused by thermal annealing and As emitter implantation. The higher Early voltages of the C transistors compared with that of the no-C transistors indicates that C incorporation in the base dramatically reduces the diffusion of B under postgrowth implantation and annealing procedures.