Al2O3 films deposited on Si wafers by plasma enhanced atomic layer deposition (PEALD) were successfully bonded by surface activated bonding (SAB) at room temperature. Results show that Si wafers covered by different ALD Al2O3 films were bonded well without big voids. The increase of deposition plasma power promotes the crystallization of Al2O3, and the additional H2 plasma post-treatment changes the number of -OH on film surface. However, both methods failed to improve the bond strength of ALD Al2O3 films. The measurement atmosphere affects the bond strength of ALD Al2O3 films and sapphire/sapphire. The bond strength measured in air was smaller than that in vacuum and in N2. Under the same measured atmosphere, the bond strength of Al2O3 films was only slightly lower than that of sapphire/sapphire.