Patent ID: 8860129

Claim:
A semiconductor device comprising: a semiconductor layer of one conductivity type including a plurality of trenches arranged with predetermined spaces, each region between neighboring trenches providing a channel; and a plurality of embedded electrodes each of which is disposed on an inner surface of a respective one of the plurality of trenches via an insulator film so as to fill in each of the plurality of trenches, the semiconductor device switching between an on state and an off state according to a voltage applied to the plurality of embedded electrodes, wherein the insulator film is disposed along the inner surface of each of the plurality of trenches so as to cover the inner surface, including an inner bottom surface and an inner side surface, of each of the plurality of trenches, each semiconductor layer neighboring the plurality of trenches is of the one conductivity type, a distance between the neighboring trenches is at least 0.05 μm and not more than 0.3 μm, the plurality of embedded electrodes are on the inner surface of each of the plurality of trenches via the insulator film so as not to make contact with the semiconductor layer, a high concentration region is on an upper surface portion of the semiconductor layer, the high concentration region having a higher impurity concentration than another portion of the semiconductor layer where the high concentration region is not formed, the plurality of trenches penetrate the high concentration region from an upper-surface-portion side of the semiconductor layer, as seen in a depth direction of the trenches, a lower end portion of the high concentration region is positioned higher than an upper end portion of the embedded electrodes, the plurality of embedded electrodes are divided into two types of embedded electrodes, namely first embedded electrodes and second embedded electrodes, to which voltages are applied separately, the plurality of embedded electrodes are arranged with predetermined spaces between them such that one of the second embedded electrodes is located between two of the first embedded electrodes, and in the off state, each depletion layer formed around any of the plurality of trenches blocks a region between the neighboring trenches, and in the on state, a depletion layer, formed around any of the plurality of trenches in which the first type of embedded electrode is embedded, disappears to permit current to flow through the region between the neighboring trenches.