A wafer to wafer structure includes a first wafer, a second wafer. A first bonding layer and a second bonding layer are disposed between the first wafer and the second wafer. A plurality of first interconnects are disposed within the he first bonding layer. A plurality of second interconnects are disposed within the second bonding layer. An interface is disposed between the first bonding layer and the second bonding layer. At least a through silicon via penetrates the first wafer, the first bonding layer and the interface to enter the second bonding layer. The through silicon via contacts one of the first interconnects and one of the second interconnects.