Wafer bonding structure, wafer bonding method and chip bonding structure

Abstract

The present invention provides a wafer bonding structure, a wafer bonding method and a chip bonding structure. A first wafer has non-metallic regions and metallic regions provided with a first metal layer. A portion of a first modification layer located above the non-metallic regions is recessed with respect to a portion of the first modification layer located above the metallic regions. A second modification layer covers the first modification layer. A chemical mechanical polishing process is performed on the second and first modification layers, which uses a polishing slurry exhibiting different polishing rates for the first and second modification layers, and as a result of which, the remaining second modification layer above the non-metallic regions is raised or recessed with respect to the remaining first modification layer above the metallic regions, resulting in the formation of first convex portions or first concave portions above the non-metallic regions. When this wafer is bonded to a wafer or dies with corresponding concavities or convexities, less gaps will be left from the bonding, improving process quality and product yield. Moreover, local concavities resulting from the CMP process can be eliminated or reduced, alleviating the problem of gaps left between bonded upper and lower wafers and achieving enhanced bonding strength and quality.