SEMICONDUCTOR DEVICE AND METHOD FOR FABRICATING THE DEVICE
First Claim
1. A semiconductor device comprising:
- a substrate;
a semiconductor layer which is arranged on the principal surface of the substrate and which is made of a wide bandgap semiconductor;
a trench which is arranged in the semiconductor layer and which has a bottom and a side surface;
an insulating region which is arranged on the bottom and side surface of the trench; and
a conductive layer which is arranged in the trench and which is insulated from the semiconductor layer by the insulating region,wherein the insulating region includes a gate insulating film that is arranged on the bottom and the side surface of the trench and a gap that is arranged between the gate insulating film and the conductive layer at the bottom of the trench, andwherein the gate insulating film contacts with the conductive layer on a portion of the side surface of the trench but does not contact with the conductive layer at the bottom of the trench, andwherein the thickness of the insulating region as measured from the bottom of the trench through the lower surface of the conductive layer is greater around the center of the trench than beside the side surface of the trench.
1 Assignment
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Accused Products
Abstract
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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Citations
17 Claims
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1. A semiconductor device comprising:
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a substrate; a semiconductor layer which is arranged on the principal surface of the substrate and which is made of a wide bandgap semiconductor; a trench which is arranged in the semiconductor layer and which has a bottom and a side surface; an insulating region which is arranged on the bottom and side surface of the trench; and a conductive layer which is arranged in the trench and which is insulated from the semiconductor layer by the insulating region, wherein the insulating region includes a gate insulating film that is arranged on the bottom and the side surface of the trench and a gap that is arranged between the gate insulating film and the conductive layer at the bottom of the trench, and wherein the gate insulating film contacts with the conductive layer on a portion of the side surface of the trench but does not contact with the conductive layer at the bottom of the trench, and wherein the thickness of the insulating region as measured from the bottom of the trench through the lower surface of the conductive layer is greater around the center of the trench than beside the side surface of the trench. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for fabricating a semiconductor device, the method comprising the steps of:
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(A) providing a substrate, on the principal surface of which a semiconductor layer of a wide bandgap semiconductor is formed; (B) forming a trench, which has a bottom and a side surface, in the semiconductor layer; (C) forming a gate insulating film on the bottom and side surface of the trench; and (D) forming a conductive layer in the trench so that the conductive layer contacts with the gate insulating film on a portion of the side surface of the trench but does not contact with the gate insulating film at the bottom of the trench and that a gap is left between the conductive layer and the gate insulating film, thereby having an insulating region defined by the gap and the gate insulating film, wherein the thickness of the insulating region as measured from the bottom of the trench through the lower surface of the conductive layer is greater around the center of the trench than beside the side surface of the trench. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification