Development of a heterogeneous integration of GaN power device on Si-LSI

Gallium Nitride(GaN) power devices have been one of the promising candidates for high-frequency and high-efficiency switching applications. However, this is not realized in current GaN power-supply products with CMOS devices where the wiring between them creates a high parasitic loss. Heterogeneous integration of them could be desirable. Two integration techniques can be employed for such 3D stacking - i) CMOS devices stacked on the GaN power devices, and ii) GaN power devices stacked on CMOS devices. Simulation results show that the GaN power devices stacked on CMOS devices is better than the alternate option. A manufacturing flow is developed to stack GaN power devices on CMOS devices through a room-temperature direct bonding process. This process enables 3D stacking without a temporary bonding and debonding process, as well, it can completely remove the buffer layer between GaN and CMOS for better efficiency.