Near-junction “hot spot” suppression with integral SiC microcontact TEC

Transistor heat generation in wide bandgap power amplifier transistors is today in excess of several kW/cm2 and can result in temperature spikes, or “hotspots,” approaching 100 K in the near-junction region. Novel, high flux cooling techniques are under development to enable successful exploitation of the inherent operational capability of wide bandgap amplifiers. Micro-contact enhanced thermoelectric coolers, using an integral pillar etched directly in the electronic substrate to concentrate cooling on the sub-mm transistor hotspot, is a most promising near-junction thermal management technique. This paper reports an experimental and numerical study of micro-contact enhanced thermoelectric cooling of a 5 kW/cm2 hotspot on a SiC substrate, demonstrating a “world record” 12 K temperature reduction for such high flux, using a commercial thermoelectric module. Moreover, using the validated numerical model, it is predicted that a 5 kW/cm2 hotspot could be cooled by up to 30 K using an optimized micro-contact and substrate geometry.