Enhanced Thermal Performance of InGaP/GaAs Collector-Up HBTs With a Miniaturized Backside Heat-Dissipation Structure

A miniaturized heat-dissipation structure is developed to reduce the operating temperature of power bipolar transistors to favorable levels, while maintaining a configuration size that is compact enough for high-efficiency operation. By placing the thermal-removal packaging at the backside of the collector-up heterojunction bipolar transistor and through the appropriate finger-pitch arrangement of the packaging design, which displays noticeable enhancement in terms of thermal management, significant reduction in the surface temperature rise is demonstrated on devices composed of the InGaP/GaAs material system. A factor of over 20 shrinkages of the consumed chip area and a 10-fold reduction in mutual heating is observed. At levels of power density up to 1.2 mW/μm ² , a power-added efficiency greater than 50% is attained for the wireless cellular power amplifier application.