The invention provides a semiconductor device including a substrate, a dielectric layer, a dummy bonding pad, a bonding pad, a redistribution layer, and a metal interconnect. The substrate includes a non-device region and a device region. The dielectric layer is on the non-device region and the device region. The dummy bonding pad is on the dielectric layer of the non-device region. The metal interconnect is in the dielectric layer of the non-device region and connected to the dummy bonding pad. The bonding pad is on the dielectric layer of the device region. The buffer layer is between the bonding pad and the dielectric layer. The buffer layer includes metal, metal nitride, or a combination thereof The redistribution layer is on the dielectric layer and connects the dummy bonding pad and the bonding pad.