Patent ID: 8217419

Claim:
A semiconductor device comprising: a semiconductor layer of one conductivity type including an inside region and an outside region disposed outside the inside region; a plurality of trenches formed in the inside region of the semiconductor layer so as to be arranged with predetermined spaces, an opening end of each of the trenches being positioned on an upper surface side of the semiconductor layer; a plurality of diffusion regions of an inverse conductivity type formed in the outside region of the semiconductor layer so as to be arranged with predetermined spaces, an upper surface of each of the diffusion regions being exposed to the upper surface side of the semiconductor layer; a plurality of embedded electrodes filled in the plurality of trenches; and an electrode layer formed on the upper surface of the semiconductor layer so as to cover the inside region and the outside region of the semiconductor layer, wherein the semiconductor device switches between an on state and an off state according to a voltage applied to the plurality of embedded electrodes, in the inside region of the semiconductor layer, a semiconductor region neighboring the plurality of trenches is of the one conductivity type, in the inside region of the semiconductor layer, an upper-surface-side part of each region between neighboring ones of the trenches of the semiconductor layer is a high-concentration region of the one conductivity type and is exposed to the upper surface side of the semiconductor layer, in the inside region of the semiconductor layer, in the off state, a depletion layer formed around the trenches fills each region between neighboring ones of the trenches of the semiconductor layer and, in the on state, at least part of the depletion layer disappears so that each region between neighboring ones of the trenches of the semiconductor layer serves as a current passage, and a junction portion between the semiconductor layer and the diffusion region makes a Zener diode in the outside region of the semiconductor layer.