A method for forming a semiconductor device with a bonding pad is disclosed. A first substrate having a device area and a bonding area is provided, wherein the first substrate has an upper surface and a bottom surface. Semiconductor elements are formed on the upper surface of the first substrate in the device area. A first inter-metal dielectric layer is formed on the upper surface of the substrate in the bonding area. A lowermost metal pattern is formed in the first inter-metal dielectric layer, wherein the lowermost metal pattern serves as the bonding pad. An opening through the first substrate is formed to expose the lowermost metal pattern.