Graphite-based heat spreaders for hotspot mitigation in 3D ICs

Heat dissipation is frequently pointed as one of the main challenges in the promising 3D integration technology. The very thin dies required to integrate high density TSVs reduce the heat dissipation capacity of the 3D stack and may provoke exacerbated hotpots. This work investigates the use of graphite-based heat spreaders to mitigate the strong hotspot dissipation issues in advanced 3D ICs. Graphite-based materials present high in-plane thermal conductivity and can be integrated into 3D stacks to compensate the poor heat spreading capacity of the thinned silicon dies. Silicon measurements are used to confirm this is a feasible and effective method for thermal management. Numerical simulations for a variety of circuit, application and integration configurations indicate this is an effective approach for hotspot mitigation in 3D ICs. Results for a memory-on-logic 3D circuit indicate a reduction of up to 40% in the peak temperature.