The Process and Mechanism of Low Temperature Silicon Carbide-to-Silicon Direct Bonding Using Amorphous Hydrogenated Silicon Carbide Films

This paper presents a low temperature process (≤450°C) to transfer amorphous, hydrogenated silicon carbide (a-SiC:H) thin films from a silicon deposition substrate to a second silicon substrate by way of a-SiC:H/Si direct bonding. Compared to traditional thin film bonding and transfer processes, the proposed approach does not rely on IC-incompatible substances or high process temperatures to form the bond. Due to the ultra-smooth a-SiC surfaces, a CMP step normally used in traditional direct bonding is not required. Using this approach, prototype structures, such as nano-gap channels and vacuum-sealed, micron-deep reservoirs with a-SiC films as capping layers have been successfully fabricated. With the aid of finite element simulation, the role of each individual parameter to the bonding process was analyzed. A calculation method based on the concept of strain-energy was introduced to estimate the lower bound of the presented bonding strength.