Development and analysis of GaN HEMT-On-Metal-On-Si wafer for 3D heterogeneous integration of GaN power devices and Si CMOS driver circuits

Abstract

GaN HEMT (High Electron Mobility Transistor) is actively utilized as a power device due to its outstanding breakdown voltage characteristics and low On-resistance. However, for more efficient utilization, integration with Si CMOS capable of performing diverse and complex functions is essential. Recent research has focused on 3D integration, which can get the decrease in formfactor size and low power loss. However, the thermal challenges associated with 3D integration, stemming from its inherently challenging heat dissipation structure, pose significant issues. In this study, we deal with the heat dissipation issues inherent in traditional 3D integration by selecting a high thermal conductivity metal as the bonding material. We have developed a novel integration approach for GaN-On-Si HEMT and Si CMOS to enable effective heat dissipation. This involves wafer bonding and selective etching processes. After fabrication, the electrical characteristics of GaN HEMT-On-Metal-On-Si Wafer were analyzed, confirming no significant changes in device performance. The primary objective of this research, overcoming heat dissipation issues, was validated through thermal simulations and actual TRM (Thermoreflectance Microscopy) measurements. Both results demonstrated an approximately 10% improvement in heat dissipation characteristics, establishing a successful heat dissipation system. If the developed technology is applied to Si CMOS integration, it is anticipated that the improved heat dissipation will be effectively realized in integrated devices.