Bonding of LiNbO₃and Si wafers at room temperature using Si nanolayers

We report the room temperature bonding of LiNbO3 and Si wafers based on the use of Si nanolayers. The proposed method employs physical sputtering, which simultaneously activates the surface of an etched Si wafer and forms a Si nanolayer on the surface of a LiNbO3 wafer. Following sputtering, both wafers are immediately brought into contact and the newly formed Si nanolayer acts as a nanoadhesive. The data presented herein demonstrate that this technique is more effective at directly bonding LiNbO3 and Si than the conventional surface-Activated bonding method. Following activation, the bonded surface energy, which reflects the bond strength, was estimated to be approximately 2.2 J m-2. This result indicates that the bonding was strong enough to withstand the processes associated with the fabrication of microelectronics devices, including wafer thinning.