Room Temperature Wafer Bonding by Surface Activated Method

The bonding of metal electrode and insulator hybrid interfaces is one of key techniques in 3D integration technology. As the surface activated bonding (SAB) is carried out at room temperature, the method is expected to be suitable for hybrid bonding. The metal materials such as Cu or Al are easy to directly bond using the SAB method, but insulator materials such as SiO2 or SiN are difficult. In this report, we propose a new bonding technique for SiO2/SiO2 bonding at room temperature using only Si ultra-thin films. We confirmed that the surface energy was about 1 J/m, which is almost the same value of Si/Si bonding prepared at room temperature by SAB. Moreover, we examined the bonding of Cu/Cu by the SAB method, and we confirmed that no micro-voids were observed at the bonding interface.