Research on the Cooling System for the System-on-Wafer Packaging

With the advantages of high-density integration and strong function, the system-on-wafer (SoW) packaging technology is a promising method, which can meet the requirements of improving system performances in the post-Moore era. However, the high-density integration also leads to a serious heat dissipation problem. This paper presents a cooling system based on fluidic cooling plates for the SoW packaging. The temperature distributions of the dummy chiplets on a wafer and the heat dissipation capacity of the cooling plates with different shapes of the fluidic channels were researched using the finite element method (FEM). The results of the cooling experiments showed that the cooling system can effectively reduce the temperatures of the chips. Compared with an average temperature of 102°C of the heating dummy chips on the wafer with natural air cooling, an average temperature of 49.2°C was obtained using the wafer-level cooling system. When the water flow rate of the cooling water in the fluidic channel was set to 1.5 L/min, the heat dissipation capacity of the series-type cooling system can reach 0.14 W/mm$^{2}$ and the temperature uniformity of the heating dummy chips on a 4-inch silicon wafer was 98.2%, which indicate the wafer-level cooling method has potential applications in the heat dissipation for the wafer-level systems.