Thermal modeling and experimental study of 3D stack package with hot spot consideration

This paper provides a unique approach to thermal modeling of BEOL (Back End Of Line) layers in a 3D stacked LSI and introduces a novel cold plate design method by using a 30 mm by 30 mm LSI as an example. The paper focuses on BEOL thermal characterization, flow rate control in branch-channels and the micro-channels behind them in a cold plate in accordance with a power map of the LSI, and an experimental setup for thermal verification. The power map had several considerable hot spots. The cold plate was able to considerably reduce temperature differences by 5°C all across the top surface of the LSI on the load condition of 120 W/cm² for hot spots and 60.5 W/cm² for other areas with regard to heat density, at a flow rate of 1 L/min. to the cold plate inlet. It also achieved a low of 5 kPa in pressure loss while the flow rate ratio of hot spots to others was controlled to approximately 5:1.