Solving Thermal Issues in a Three Dimensional Stacked Quad Core Processor by Microprocessor Floor Planning, Microchannel Cooling, and Insertion of Through Silicon Vias

Abstract

The electronics industry is heading toward the threedimensional (3D) microprocessor to cope with higher computing workloads. The 3D stacking of the processor and the memory components reduces the communication delay in multicore systemonachip (SoCs), owing to reduced system size and shorter interconnects. The shorter interconnects in a multicore system lowers the memory access latencies and contributes to improvements in memory access bandwidth. The shorter interconnects in stacked architectures also enables small drivers for interconnections which further reduce interconnectionlevelenergy dissipations. On the down side, the 3Dstacked architectures have high thermal resistance, which in conjunction with poor thermal management techniques, poses a thermal threat to the reliability of the device. This paper establishes the significance of the microprocessor floor planning and singlephase microchannel cooling for solving the thermal issues arising in the 3Dstackedquadcore processor. The 3Dstackedquadcore processor considered in this study comprises of symmetric nonuniformly powered quadcore processor, liquidcooled microchannel heat sink, dynamic random access memory (DRAM), thermal interface material (TIM), and heat spreader. The electrical throughsiliconvias (TSVs) between the processor and DRAM serve as interconnects, while the thermal TSVs reduce the internal thermal resistance. The effective cooling of the 3Dstackedquadcore processor depends on the TSVs, quadcore layout and the optimized design of the microchannel heat sink for the desired coolant. The microchannel cooling of the 3Dstacked processor is done both by planar flow and impingement flow. The thermal efficiency of the cooling techniques is evaluated on the basis of hot spot temperature, hot spot spread, and number of hot spots.