High-speed small-scale InGaP/GaAs HBT technology and its application to integrated circuits

We have developed the advanced performance, small-scale InGaP/GaAs heterojunction bipolar transistors (HBTs) by using WSi/Ti base electrode and buried SiO/sub 2/ in the extrinsic collector. The base-collector capacitance C/sub BC/ was further reduced to improve high-frequency performance. Improving the uniformity of the buried SiO/sub 2/, reducing the area of the base electrode, and optimizing the width of the base-contact enabled us to reduce the parasitic capacitance in the buried SiO/sub 2/ region by 50% compared to our previous devices. The cutoff frequency f/sub T/ of 156 GHz and the maximum oscillation frequency f/sub max/ of 255 GHz were obtained at a collector current I/sub C/ of 3.5 mA for the HBT with an emitter size S/sub E/ of 0.5/spl times/4.5 /spl mu/m/sup 2/, and f/sub T/ of 114 GHz and f/sub max/ of 230 GHz were obtained at I/sub C/ of 0.9 mA for the HBT with S/sub E/ of 0.25/spl times/1.5 /spl mu/m/sup 2/. We have also fabricated digital and analog circuits using these HBTs. A 1/8 static frequency divider operated at a maximum toggle frequency of 39.5 GHz with a power consumption per flip-flop of 190 mW. A transimpedance amplifier provides a gain of 46.5 dB/spl middot//spl Omega/ with a bandwidth of 41.6 GHz at a power consumption of 150 mW. These results indicate the great potential of our HBTs for high-speed, low-power circuit applications.