Simulations of Non-Uniform, Non-Linear Collector Doping Profiles for SiGe HBTs

Through 1D device simulations it has been shown that there is some advantage to engineering the shape of the collector profile in SiGe HBT´s but only in certain regimes. Power law profiles are shown to be superior to a flat profile only for low breakdown cases. For high-breakdown devices there is little or no advantage to shaping the profile. For the low breakdown case, profiles with their dose distributed more on the subcollector side and less on the base side are superior although it is difficult to keep adding dose ad infinitum to these types of profiles so some balance must be struck between the total dose necessary and the shape of profile used