Flip-chip X-band operation of thermally-shunted microwave HBT´s with sub-micron emitters

Design and fabrication methods were developed for GaAs-based flip-chip HBTs with emitter sizes down to 1 /spl mu/m or less. We have fabricated and tested identical size devices in both the conventional and the flip-chip configuration on the same wafer to make a direct comparison of their DC, microwave, and thermal properties. It was shown that flip-chip mounted microwave HBTs can produce the same or better electrical performance than their conventional upright counterparts while offering a 37% improvement in thermal resistance.