Abstract: The present invention provides an insulated gate semiconductor device which has floating regions around the bottoms of trenches and which is capable of reliably achieving a high withstand voltage. An insulated gate semiconductor device 100 includes a cell area through which current flows and an terminal area which surrounds the cell area. The semiconductor device 100 also has a plurality of gate trenches 21 in the cell area and a plurality of terminal trenches 62 in the terminal area The gate trenches 21 are formed in a striped shape, and the terminal trenches 62 are formed concentrically. In the semiconductor device 100, the gate trenches 21 and the terminal trenches 62 are positioned in a manner that spacings between the ends of the gate trenches 21 and the side of the terminal trench 62 are uniform. That is, the length of the gate trenches 21 is adjusted according to the curvature of the corners of terminal trench 62.

Abstract: The invention is intended to present an insulated gate type semiconductor device that can be manufactured easily and its manufacturing method while realizing both higher withstand voltage design and lower on-resistance design. The semiconductor device comprises N+ source region 31, N+ drain region 11, P? body region 41, and N? drift region 12. By excavating part of the upper side of the semiconductor device, a gate trench 21 is formed. The gate trench 21 floating region 51 is provided beneath the gate trench 21. A further trench 35 differing in depth from the gate trench 21 may be formed, a P floating region 54 being provided beneath the trench 25.