Abstract: Embodiments provide a method of performing a carrier switch for a device wafer, attaching a second wafer and removing a first wafer. A buffer layer is deposited over the device wafer, buffer layer reducing the topography of the surface of the device wafer. After the carrier switch a film-on-wire layer is removed from the buffer layer and then the buffer layer is at least in part removed.

Abstract: A first polymer layer is formed across a package region and a test region. A first metal pattern is formed in the package region and a first test pattern is simultaneously formed in the test region. The first metal pattern has an upper portion located on the first polymer layer and a lower portion penetrating through the first polymer layer, and the first test pattern is located on the first polymer layer and has a first opening exposing the first polymer layer. A second polymer layer is formed on the first metal pattern in the package region and a second test pattern is simultaneously formed on the first test pattern in the test region. The second polymer layer has a second opening exposing the upper portion of the first metal pattern, and the second test pattern has a third opening greater than the first opening of the first test pattern.