Room-temperature bonding of Al(2)O(3) thin films deposited using atomic layer deposition

In this study, room-temperature wafer bonding of Al(2)O(3) thin films on Si thermal oxide wafers, which were deposited using atomic layer deposition (ALD), was realized using the surface-activated bonding (SAB) method. Transmission electron microscopy (TEM) observations indicated that these room-temperature-bonded Al(2)O(3) thin films appeared to work well as nanoadhesives that formed strong bond between thermally oxidized Si films. The perfect dicing of the bonded wafer into dimensions of 0.5 mm × 0.5 mm was successful, and the surface energy, which is indicative of the bond strength, was estimated to be approximately 1.5 J/m(2). These results indicate that strong bonds can be formed, which may be sufficient for device applications. In addition, the applicability of different Al(2)O(3) microstructures in the SAB method was investigated, and the effectiveness of applying ALD Al(2)O(3) was experimentally verified. This successful SAB of Al(2)O(3) thin films, which is a promising insulator material, opens the possibility of future room-temperature heterogenous integration and wafer-level packaging.