Thermal Modeling of 3-D Stacked DRAM Over SiGe HBT BiCMOS CPU

We have previously evaluated the feasibility of a serial code accelerator core with 3-D DRAM stacked on the core operating at high frequencies. While operating at such high frequencies (> 24 GHz), there are concerns with removing heat from the 3-D stack. We propose the use of thin diamond sheets, which have high thermal conductivity, as a heat spreader by bonding it close to the processor core substrate and memory stacks. We show, through thermal modeling using COMSOL finite-element analysis tools, the feasibility of diamond as an effective heat spreader in a processor-memory 3-D stack.