A new self-alignment technology using bridged base electrode for small-scaled AlGaAs/GaAs HBT's

The fabrication and characterization of a new self-aligned HBT utilizing bridged base-electrode technology (BBT) are presented. This new technology simplifies the fabrication process and relaxes the limitations in device size scaling, thus decreasing the emitter size to 1 mu m*1 mu m. In spite of a large junction periphery area ratio, a good current gain of more than 10 is obtained in an HBT with an emitter size of 1 mu m*1 mu m. A series of fabricated HBTs shows excellent high-speed performance. The highest values of f/sub T/=90 GHz and f/sub max/=63 GHz are obtained in an HBT with an emitter size of 1 mu m*5 mu m. The realization of HBTs with small emitters and excellent high-frequency characteristics demonstrates the effectiveness of this new technology. >