Wafer-bonding structure and method of forming thereof

A method of forming a wafer-bonding structure includes a wafer-bonding step, a through silicon via forming step and a forming bonding pad step. In the wafer-bonding step, each of at least two wafers has a bonding surface, and the wafers are corresponding to and bonded to each other by the bonding surfaces thereof. In the through silicon via forming step, a through silicon via structure is formed on at least one side of a seal ring structure of one of the wafers, a conductive filler is disposed in the through silicon via structure, and the through silicon via structure is overlapped the seal ring structure of one of the wafers and a portion of a seal ring structure of another one of the wafers. In the forming bonding pad step, a bonding pad is formed on an outer surface which is relative to the bonding surface of the wafer with the through silicon via structure, so as to form the wafer-bonding structure. Therefore, it is favorable for enhancing a connecting strength and a conductivity between the wafers.