Low-Temperature, Strong SiO_(2)-SiO_(2) Covalent Wafer Bonding for III-V Compound Semiconductors-to-Silicon Photonic Integrated Circuits

摘要

We report a low-temperature process for covalent bonding of thermal SiO_(2) to plasma-enhanced chemical vapor deposited (PECVD) SiO_(2) for Si-compound semiconductor integration. A record-thin interfacial oxide layer of 60 nm demonstrates sufficient capability for gas byproduct diffusion and absorption, leading to a high surface energy of 2.65 J/m~(2) after a 2-h 300 deg C anneal. O_(2) plasma treatment and surface chemistry optimization in dilute hydrofluoric (HF) solution and NH_(4)OH vapor efficiently suppress the small-size interfacial void density down to 2 voids/cm~(2), dramatically increasing the wafer-bonded device yield. Bonding-induced strain, as determined by x-ray diffraction measurements, is negligible. The demonstration of a 50 mm InP epitaxial layer transferred to a silicon-on-insulator (SOI) substrate shows the promise of the method for wafer-scale applications.