Collector vertical scaling and performance tradeoffs in 300 GHz SiGe HBTs

This study investigates the impact of the collector vertical scaling on the tradeoff between f/sub T/ and f/sub max/ with SiGe HBTs of /spl sim/300 GHz performance. We further proceed to discuss its impact on the avalanche breakdown behavior of the devices. It is observed that the selectively implanted collector (SIC) dose variation affects f/sub T/ and f/sub max/ in opposite directions, in 300 GHz SiGe HBTs, which can be exploited to selectively optimize the devices for either f/sub T/ or f/sub max/ depending on the requirement from a given application. This trend also indicates, along with the observed SIC dose dependence of the breakdown voltages, that the traditional speed-breakdown voltage (BV) tradeoff is valid for f/sub T/-BV, but not necessarily for f/sub max/-BV.