A Simulation Study of Oxide Thickness Effect on the Performance of SiGe HBTs with SOI Structure

Using a TCAD simulator, we examine the oxide thickness effect on electrical characteristics of the SiGe HBT on SOI substrates. We have investigated this effect on Early voltage, cut-off frequency, and maximum oscillation frequency for SiGe HBT on SOI substrate. It is found that the maximum oscillation frequency (f_max) of SiGe HBT on SOI substrate is much better than that of conventional SiGe HBT. The maximum oscillation frequency increases with the increase in oxide thickness and tend to saturate at oxide thickness of 0.15 mum. In order to study oxide thickness on self-heating effect, thermal resistances are also simulated.