Enhancement of Hotspot Cooling With Diamond Heat Spreader on Cu Microchannel Heat Sink for GaN-on-Si Device

Abstract

The diamond heat spreader has been directly attached between the test chip and the Cu microchannel heat sink for thermal performance enhancement of the GaN-on-Si device. In the fabricated test vehicle, the small heater is used to represent one unit of transistor. Experimental tests have been conducted on the fabricated test vehicle to investigate the performance. Two types of simulation models have been constructed in COMSOL, considering the multiphysics features and temperature-dependent material properties. The submodel in conjunction with the main model is constructed to predict the thermal performance of the GaN-on-Si structure. The heating power, which is concentrated on eight tiny heaters of size 350 $\,\times\,$ 150 $\mu{\rm m}^{2}$ , is varied from 10 to 50 W. With the diamond heat spreader attached to the liquid-cooled microchannel heat sink, the maximum heater temperature can be reduced by 11.5%–22.9%, while the maximum gate temperature can be reduced by 8.9%–18.5%. Consistent results from the experimental and simulation studies have verified the enhancement of the hotspot cooling capability using directly attached diamond heat spreader.