The effect of hydrogen passivation on electrical characteristics of double-polysilicon self-aligned bipolar transistors

The influence of hydrogen passivation using forming gas annealing (FGA), on the electrical performance of double-polysilicon self-aligned bipolar junc tion transistors was investigated. While the collector current remained ess entially unaffected after FGA, the base current decreased substantially. As a result, the peak DC current gain increased by a factor of three. Identif ication of the Various base current components showed that the SiO2/monosil icon interface area along the perimeter of the emitter window, were effecti vely passivated after FGA, both in the quasi-neutral base and in the space charge region. The FGA treatment was also found to lead to an increase in t he peak cut-off frequency by up to 40%. This is explained by a decrease in emitter-base junction capacitance, which was verified experimentally. (C) 1 999 Elsevier Science Ltd. All rights reserved.