Microcontact-Enhanced Thermoelectric Cooling of Ultrahigh Heat Flux Hotspots

The dissipated power of insulated gate bipolar transistor and high electron mobility transistor amplifiers is typically nonuniform, resulting in areas of elevated temperature, or hotspots, which can have very large heat fluxes, on the order of 1000 W/cm². While various bulk cooling systems are being researched to remove large amounts of heat, they uniformly reduce the chip temperature, leaving the temperature nonuniformity. Therefore, advanced hotspot cooling techniques, which provide localized cooling, are also required to unlock the full potential of cutting edge power devices. Thermoelectric coolers have previously been demonstrated as an effective method of producing on-demand cooling for the removal of localized hotspots. However, the heat flux of the hotspots that can be cooled is limited by the maximum cooling flux of thermoelectric devices. This paper demonstrates the thermal and reliability performance of a microcontact-enhanced thermoelectric cooling configuration, which uses a contact structure etched directly out of the electronic substrate to concentrate the cooling produced by a commercially available thermoelectric module. The 22 K of cooling, resulting in a hotspot temperature rise of <;6 K for a heat flux of 2.5 kW/cm², was experimentally demonstrated using a Laird HV37 thin-film thermoelectric module with a maximum device level cooling flux of 66 W/cm². A numerical model was created, and it is predicted that when the chip and microcontact geometry is optimized, hotspots with heat fluxes in excess of 3 kW/cm² can be cooled by nearly 40 K, reducing the hotspot temperature rise to 0 K.