Heat transfer and pressure drop experiments on CMOS compatible microchannel heat sinks for monolithic chip cooling applications

Novel CMOS compatible microchannel heat sinks are designed, fabricated and tested for monolithic liquid cooling of integrated circuits. The proposed heat sink is fabricated by low temperature surface micromachining processes and requires no design change of the electronic circuitry underneath, hence, can be produced by adding a few more steps to the standard CMOS fabrication flow. The microchannel heat sinks were tested successfully under various heat flux and coolant flow rate conditions. The cooling tests have shown that the microchannel heat sinks were able to extract up to 127 W/cm ² heat flux from a hot spot, and 50 W/cm ² heat flux in steady state continuous operation from the entire heated surface. The obtained Nusselt number correlations fall between two previously proposed correlations for laminar flow in rectangular microchannels. Friction factor results are also in agreement with the laminar theory with slight deviations.