Deep submicron CMOS based on silicon germanium technology

The advantages to be gained by using SiGe in CMOS technology are examined, Conventional MOSFETs are compared with SiGe heterojunction MOSFETs suitable for CMOS technology and having channel lengths between 0.5 and 0.1 μm. Two-dimensional computer simulation demonstrates that the improved mobility in the SiGe devices, due to higher bulk mobility and the elimination of Si/SiO₂ interface scattering by the inclusion of a capping layer, results in significant velocity overshoot close to the source-end of the channel. The cut-off frequency, f_t , is found to increase by around 50% for n-channel devices while more than doubling for p-channel devices for typical estimates of mobility. The results offer the prospect of a more balanced CMOS and improved circuit speed especially when using dynamic logic