Unlocking the True Potential of 3-D CPUs With Microfluidic Cooling

3-D integration is a promising technology to sustain transistor density scaling in the future, as well as facilitating new architectural designs that were not possible with traditional integration techniques. However, 3-D integration comes with some serious challenges, chief among them heat removal. A promising technology for thermal issues is microfluidic (MF) cooling. In this paper, we perform a design space analysis study on 3-D CPUs. We show that aggressive cooling solutions such as MF cooling are necessary to unlock the true potential of 3-D ICs. Without such cooling the thermal feasibility region of the design space is significantly reduced. We observe that interactions between thermal, electrical, and physical aspects of 3-D CPUs with MF cooling are substantial, and must be cooptimized during our analysis to correctly identify optimal design points. We simulate a spectrum of 3-D CPU architectures which offer vast improvements to performance, but are energy inefficient and thermally infeasible with air cooling. Furthermore, we show a 2.30× (1.59×) improvement in performance (energy efficiency) when MF cooling and floorplan cooptimization are added to our design space analysis simulation flow.