Characteristics of 3D-Integrated GaN Power Module Under Multi Heat Source Coupling

3D-integrated GaN power modules can effectively reduce parasitic parameters and enhance the power system's performance. However, the heat from each power chip during operation can lead to a mutual thermal coupling effect, potentially causing performance drift of the GaN power chips. This work investigates the impact of the thermal coupling effect in a 3D-integrated GaN power module on the characteristics of its GaN power chips. The GaN power chips' characteristics are measured before and after the other power chips in the 3D-integrated GaN power module and after applying <i>V</i>_GS/<i>V</i>_DS = 3 V/1 V for 60 s. The results indicate that the thermal coupling effect in 3D-integrated GaN power modules can cause a rightward shift in the threshold voltage, reduce the response speed and on-state current, and also increase the leakage current of GaN power chips. In severe cases, the threshold voltage drift can reach up to 0.26 V, the device's response time can increase by as much as 217 μs, the on-state current can decrease by 1.7 A, and the off-state leakage current can increase by more than 80 times. The impact of the thermal coupling effect is related to the direction of heat flow and the distance between chips. The closer the chips are to each other, the stronger the thermal coupling. It has a greater impact on the performance of chips near the bottom substrate and a lesser impact on the performance of chips at the top of the module. Typically, the influence of the thermal field generated by two chips working simultaneously is more significant than that of the thermal field generated by a single chip working alone.