a superjunction device is disclosed , wherein p - type regions in an active region are not in contact with the n + substrate , and the distance between the surface of the n + substrate and the bottom of the p - type regions in the active region is greater than the thickness of a transition region in the n - type epitaxial layer . methods for manufacturing the superjunction device are also disclosed . the present invention is capable of improving the uniformity of reverse breakdown voltage and overshoot current handling capability in a superjunction device .