Optimization of base-to-emitter spacer thickness to maximize the frequency response of bipolar transistors

Abstract

The impacts of base-to-emitter spacer thickness on the unity gain frequency ( f T), base resistance ( r B), base collector capacitance ( C BC) and maximum oscillation frequency ( f max) of a bipolar junction transistor (BJT) are studied. Using the extracted Y-parameters from a simulated device with structural parameters calibrated to an actual process, the resulting f T and f max with different spacer thickness is reported. A tradeoff between peak f T and f max is observed and the process window to obtain high f T and f max is proposed.