Interfacial Engineering of SiC/Si Heterostructures via Surface-Activated Direct Bonding: Crystallographic Orientation Effects and Stress Mitigation Strategies

This work presents a comparative study of heterojunctions based on 6-inch wafers between silicon carbide and silicon (including Si-face of 4H-SiC and Si, and C-face of 4H-SiC and Si) fabricated via low temperature surface-activated bonding performed on the EVG ComBond system. We systematically investigate crystallographic orientation-dependent effects on interfacial structure and rigorously characterize internal stress distributions within wafer-bonded heterojunction structures through advanced analytical techniques. The interfacial layer properties and mechanical bonding strength are quantitatively assessed. For the first time, in situ heating transmission electron microscopy reveals real-time low-temperature recrystallization at the heterogeneous bonding interface. Our results establish fundamental correlations between process parameters and interfacial integrity, providing insights into the physical mechanism of SiC/Si heterostructures using advanced low-temperature wafer bonding technology. These findings provide guidance for the robust development of SiC/Si heterojunctions and highlight their potential for next-generation wafer-level packaging in high-power and extreme-environment electronics.