Mechanism of sol-gel intermediate layer low temperature wafer bonding

Low temperature silicon-to-silicon wafer bonding has been successfully performed using a sol-gel intermediate layer, with bond strengths of up to 35 MPa at a bonding temperature of 100°C, which is near the fractured strength of the bulk silicon. The bonding mechanism for this low temperature sol-gel intermediate layer wafer bonding is found to be related to the surface smoothness, porous intermediate layer and high density of OH groups, and the small amount of absorbed water on the sol-gel coating prior to bonding.