Investigation of the interface between LiNbO₃ and Si fabricated via room-temperature bonding method using activated Si nano layer

Abstract Wafer-level bonding of LiNbO 3 and Si has been difficult to achieve owing to the large mismatch in their thermal expansion coefficients, which prevents the use of bonding methods involving annealing. As a solution, we have developed a room-temperature wafer-bonding method that uses an activated Si nanolayer as an adhesive. In this study, we analyzed the bond interface between LiNbO 3 and Si that formed via this room-temperature bonding method. The atomic structures of the bonding interface of LiNbO 3 /Si and the debonded surfaces were investigated in detail. Furthermore, it was found that the bond strength between the activated Si nanolayers and Si was as strong as that of Si/Si bonded using the standard surface-activated bonding method. These findings provide evidence for a strong bond between LiNbO 3 and Si at room temperature.