Direct Wafer Bonding of Silicon Carbide and Copper

Silicon carbide (SiC), known for its wide bandgap and exceptional resistance to high temperatures and pressures, is widely used in high-power devices that operate efficiently at temperatures exceeding 400 °C. Especially when combined with Direct Bonded Copper (DBC) substrates, these devices exhibit excellent heat dissipation capabilities. However, during packaging, conventional soldering materials start to degrade around 200 °C due to oxidation or aging, leading to diminished reliability and shorter device lifespans. In this study, we demonstrate the fabrication of high-quality SiC/Cu systems using the wafer bonding approach, achieving an interface bonding strength of ∼57 MPa. Atomically resolved electron microscopy and spectroscopy characterizations reveal that the bonding is robust across all Cu crystal orientations and free of oxide layers. Furthermore, owing to the excellent interface quality, the interfacial thermal conductance, as measured by time-domain thermoreflectance (TDTR) measurements, reaches an impressively high value of ∼0.128 GW/m²K, which is further corroborated by thermal simulation calculations. Subsequent nanoscale phonon measurements and analyses disclose that interface phonons play a crucial role in endowing the SiC/Cu bonding system with excellent thermal performance. This study demonstrates that the direct wafer bonding strategy is an effective approach for fabricating high-quality SiC/Cu heterostructures with robust mechanical and thermal properties.