Patent ID: 7642139

Claim:
A production method for a semiconductor device which includes a super junction structural portion provided on a semiconductor substrate of a first conductivity and including drift layers of the first conductivity and RESURF layers of a second conductivity different from the first conductivity, the drift layers and the RESURF layers being laterally arranged in alternate relation in a direction parallel to the semiconductor substrate, the production method comprising the steps of: forming a semiconductor layer of the first conductivity on the semiconductor substrate; forming a trench in the semiconductor layer, the trench penetrating through the semiconductor layer to reach the semiconductor substrate; filling a filling material in a predetermined bottom portion of the trench, so that a filling material portion is provided in the bottom portion of the trench up to a predetermined upper surface position which is shallower than an interface between the semiconductor substrate and the semiconductor layer, a void is provided in an upper portion of the trench above the predetermined upper surface position, and a part of the filling material is located in the semiconductor substrate, wherein the filling step further includes the steps of: supplying the filling material into the trench up to a position which is shallower than the predetermined upper surface position; after the filling material supplying step, etching back the supplied filling material to the predetermined upper surface position; and after the filling step, introducing an impurity of the second conductivity into a portion of the semiconductor layer exposed to an interior side wall of the trench, whereby the RESURF layers of the second conductivity are each formed alongside the interior side wall of the trench and the drift layers are each defined by a portion of the semiconductor layer remaining intact.