Experimental Investigation of In-Plane Thermal Isolation Strategies for 2.5D Silicon-Based Integration Systems

Abstract In-plane thermal crosstalk is a crucial thermal management challenge, especially in silicon-based 2.5D heterogeneous integration systems, where the relatively high thermal conductivity of silicon interposers (∼150 W/m K) creates strong thermal coupling between adjacent dies. This work studies thermal insulation strategies to reduce in-plane thermal crosstalk in such systems. Dual-chip thermal test vehicles (TTVs) were designed and fabricated to evaluate insulation performance with natural convection cooling. Trenches were etched between the two chips on the silicon interposer and filled with either glass or air, enabling systematic evaluation of both the choice of material and geometry. Steady-state temperature distributions were measured under various power levels using four-wire sensing and compared to high-resolution infrared thermal images. Results with the isolation strategies were compared against a baseline solid silicon interposer. Experimental results show that at low power densities, adding the insulation material has limited influence (ΔT < 5.6 °C), whereas at higher power levels, both material selection and trench dimensions significantly affect performance. These findings provide quantitative design guidelines for improving thermal management in high-density 2.5D integration systems.