The silicon on diamond structure by low-temperature bonding technique

We demonstrate fabrication a silicon on diamond structure at around room temperature using a plasma-activated bonding (PAB) method. Thin and flat silicon-dioxide (SiO₂) film was used as an activation layer for PAB. The SiO₂ film was prepared by a chemical vapor deposition and then a chemical mechanical polishing (CMP). The surface roughness after the CMP were average ~1 nm rms at 300 nm thick. Thinning of the SiO₂ film was carried out using 2.5%HF solution. We found that there are no significant change in the surface roughness after the thinning process. The roughness of SiO₂ less than or equal to 1 nm is required for success bonding at low-temperature with vacuum environment. The scanning electron microscope has shown seamless at the bonding interface that proves to good bonding result.