Suppression of boron transient-enhanced diffusion in SiGe HBTs by a buried carbon layer

The experiments described in this paper show that base broadening effects due to extrinsic base implantation in SiGe HBTs can be suppressed by introducing a buried carbon layer under the SiGe/Si base prior to epitaxy. They also demonstrate that SiGe HBTs with excellent static (/spl beta//spl times/V/sub AF//spl sim/10/sup 4/ V) and dynamic (f/sub T/B/spl times/BV/sub CEO//spl sim/200 GHz/spl times/V) characteristics can be fabricated using an epitaxially aligned in-situ-doped polysilicon emitter and an appropriately designed SiGe/Si base profile.