Patent ID: 7943466

Claim:
A method for forming a semiconductor device comprising the steps of: providing a region of semiconductor material having a first major surface; forming a trench in the region of semiconductor material extending from the first major surface; forming a plurality of semiconductor layers within the trench including at least two opposite conductivity type semiconductor layers, and at least one buffer layer separating the at least two opposite conductivity type semiconductor layers, wherein the buffer layer has a lower dopant concentration than the at least two opposite conductivity type semiconductor layers at formation; removing portions of the plurality of semiconductor layers so that remaining portions of the plurality of semiconductor layers are recessed below the first major surface to form a sub-surface trench compensation region in a lower portion of the trench; forming a control electrode in an upper portion of the trench overlying the sub-surface trench compensation region; forming a body region within the region of semiconductor material, wherein the control electrode is configured to establish a channel in the body region when the device is in operation; and forming a source region within the body region.