Effect of Compressive Stress on Evolution and Healing Kinetics of Artificial Voids in Highly (111)-Oriented Cu-Cu Wafer Bonding at 300°C

Cu- Cu direct bonding has attracted much attention because it has been implemented in three-dimensional integrated circuits. The interfacial voids are inevitable since atomically smooth surfaces are not available. The presence of interfacial voids might lead to degraded reliability of devices. Cu-Cu bonding usually accompanies oxide-oxide bonding to form hybrid bonding. Compressive stress can occur at Cu-Cu bonded interface at elevated temperature. In this study, artificial voids were introduced at bonded interfaces. The effect of compressive stress on the evolution and the healing kinetics of interfacial voids was investigated at 300 °C.