Fabrication of SiC-on-insulator substrate via a low-temperature plasma activated bonding process

Silicon carbide is well known as a compelling third-generation semiconductor material. SiC-on-insulator substrate performs superior electronic isolation and operates as a high-speed and high-power platform. In contrast to existing manufacturing methods, there is an urgent need for a low temperature process with lower interfacial stress and high quality. Wafer direct bonding has been developed for many years because this technology enables composite structures regardless of material. However, the bonded sample should anneal to further improve the strength. The interfacial stress caused by high temperature is still unsolved. Plasma activated bonding is known as a method that requires a lower annealing process. Here, we adopt O
₂
plasma activation as a pre-treatment and bond hydrophilic surfaces at room temperature. Furthermore, we designed a step annealing curve to reduce the maximum temperature to 200 °C while ensuring bonding strength. A uniform and defect-free bonding interface can be observed by transmission electron microscopy. This technique is suitable for fabricating high quality SiC-on-insulator platforms for optoelectronic devices.