A debonder apparatus includes a chuck assembly, a flex plate assembly, a contact roller and a resistance roller. The chuck assembly includes a chuck and a first wafer holder holding a first wafer of a bonded wafer pair in contact with the chuck. The flex plate assembly includes a flex plate and a second wafer holder holding a second wafer of the bonded wafer pair in contact with the flex plate. The flex plate is placed above the chuck. The contact roller is arranged adjacent to a first edge of the chuck and pushes and lifts up a first edge of the flex plate, while the resistance roller traverses horizontally over the flex plate and applies a downward force upon the flex plate and thereby the bonded wafer pair delaminates along a release layer and the first and second wafers are separated from each other.