Thermal Management of Heterogeneously Integrated HBM-GPU Module with Step Height Difference

System-level thermal solutions of a 2.5-D integrated HBM-GPU with die height variance are analyzed in this paper. The growing geometrical complexity of multi-chip architectures and the increasing power density of chips motivate the need for advanced thermal management solutions. To this end, we explore multiple thermal approaches including topside cooling solutions, structural component integration, and material selections to reduce the system temperature while addressing the height mismatch between the HBM and GPU. The HBM-GPU module is modeled with a power dissipation of up to 30 W from the 12-stacked HBM and 2000 W from the GPU. By using computational fluid dynamics (CFD) and heat transfer analysis, various thermal case studies are evaluated. While the effects of liquid cooling solutions, structural copper integration, and highthermal conductive epoxy molding compound (EMC) have been discussed individually, the combined implementation of these strategies reduces the maximum system temperature below 98.4 ${ }^{\circ} \mathrm{C}$, achieving up to 22.05% reduction compared to conventional active air-cooling solutions. Therefore, our findings highlight the system-level thermal impact based on different cooling solutions in an effort to explore technology options.