Impact study of the process thermal budget of advanced CMOS nodes on SiGe HBT performance

The objective of this paper is to predict the main electrical characteristics of SiGe NPN HBTs, like the transit frequency fT, internal capacitances and pinched base sheet resistance for the next CMOS nodes by means of process and hydrodynamic simulations. The as-deposited BiCMOS055 vertical doping profile is exposed to the thermal budgets from existing CMOS040, CMOS028, CMOS028FDSOI and CMOS014FDSOI technologies by TCAD simulation. Obtained results show that, thanks to the reduction of the process thermal budget, the maximum fT could reach 370 GHz with two different assumptions: identical doping level at both BE and BC junctions and identical BE capacitance. Additionally, the evolution of the dopants´ diffusion with ST´s fabrication steps is clarified for BiCMOS055 in this study.