| 摘要 |
The semiconductor device 100 of this invention includes: a semiconductor layer 2 arranged on the principal surface of a substrate 1 and made of a wide bandgap semiconductor; a trench 5 which is arranged in the semiconductor layer 2 and which has a bottom and a side surface; an insulating region 11 arranged on the bottom and side surface of the trench 5; and a conductive layer 7 arranged in the trench 5 and insulated from the semiconductor layer 2 by the insulating region 11. The insulating region 11 includes a gate insulating film 6 arranged on the bottom and the side surface of the trench 5 and a gap 10 arranged between the gate insulating film 6 and the conductive layer 7 at the bottom of the trench 5. The gate insulating film 6 contacts with the conductive layer 7 on a portion of the side surface of the trench 5 but does not contact with the conductive layer 7 at the bottom of the trench 5. The thickness of the insulating region 11 measured from the bottom of the trench 5 through the lower surface of the conductive layer 7 is greater around the center of the trench than beside its side surface.
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