Oxides formation on hydrophilic bonding interface in plasma-assisted InP/Al2O3/SOI direct wafer bonding.

Successful direct wafer bonding between InP and silicon-on-insulator (SOI) wafers has been demonstrated by adopting a 20-nm-thick Al₂O₃ as the intermediate layer. A detailed investigation on the property of the bonding interface is carried out. Water contact angle test reveals an improved hydrophilicity for both the InP and the Al₂O₃/SOI wafers after oxygen plasma surface activation. X-ray photoelectron spectroscopy is employed to characterize the bonding interface before and after the wafer bonding process. It is found that oxides are formed on the bonding interface during bonding, which helps ensure high quality hydrophilic bonding. [ABSTRACT FROM AUTHOR]