3-D Stacked Tier-Specific Microfluidic Cooling for Heterogeneous 3-D ICs

Cooling is a significant challenge for high-performance and high-power 3-D ICs. In this paper, tier-specific microfluidic cooling technology is proposed and experimentally evaluated in a 3-D stack. Different stacking scenarios are experimentally evaluated including: 1) a memory-on-processor stack; 2) a processor-on-processor stack with equal power dissipation; 3) a processor-on-processor stack with different power dissipations; and 4) a two-tier 3-D stack with each tier containing four cores along the flow direction. Compared with conventional microfluidic cooling, the tier-specific cooling is shown to reduce the pumping power by 37.5% by preventing overcooling when an operating temperature is specified. The results are benchmarked with an air-cooled heat sink. The impact of the lateral thermal gradient along the flow direction on the electrical performances, including leakage power and clock frequency, is analyzed.