Interfacial reconstruction and microstructural evolution of SiC/SiC wafers via surface activated bonding

Surface activated bonding (SAB) has emerged as a key technology for fabricating SiC/SiC homo-structures, which are critical for high-voltage vertical power devices and all-SiC microelectromechanical systems (MEMS). However, conventional SAB is hindered by its reliance on continuous ultra-high vacuum (UHV) environments for in-situ alignment and pressing, resulting in high equipment complexity and restricted throughput. To address these limitations, this study investigates the interfacial reconstruction and microstructural evolution of SiC/SiC wafers bonded via an ex-situ SAB approach enabled by ion-beam surface modification. The introduction of a nanoscale surface modification layer preserves interfacial reactivity during wafer transfer and pre-bonding under ambient conditions. Microstructural characterizations reveal that this layer acts as a mediator to facilitate atomic-level interconnection. Upon subsequent thermal annealing, the interface undergoes structural reconstruction, evolving into a dense, amorphous inter-diffusion layer (approximately 10.2 nm thick). Mechanical evaluations confirm that the bonded interfaces exhibit a tensile strength of 4–5 MPa. This work elucidates the microstructural evolution mechanisms of SiC interfaces, providing fundamental insights and a practical pathway for wafer integration.