SILICON CARBIDE SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME
First Claim
1. A silicon carbide semiconductor device comprising:
- a first or second conductivity type substrate that is made of silicon carbide;
a drift layer that is disposed on the substrate, and made of a first conductivity type silicon carbide lower in impurity concentration than the substrate;
a base region that is disposed on the drift layer, and made of a second conductivity type silicon carbide;
a source region that is disposed on the base region, and made of a first conductivity type silicon carbide higher in impurity concentration than the drift layer;
a contact region that is connected to the base region, and made of a second conductivity type silicon carbide higher in impurity concentration than the base layer;
a trench that extends to a position deeper than the base region from a surface of the source region;
a second conductivity type layer that is disposed in a corner of a bottom of the trench, made of a second conductivity type silicon carbide, and has a triangular round shape in cross-section taken along a depth direction of the trench;
a gate insulating film that is disposed on an inner wall surface of the trench on the second conductivity type layer;
a gate electrode that is disposed on the gate insulating film within the trench;
a source electrode that is electrically connected to the base region through the source region and the contact region; and
a drain electrode that is disposed on a rear side of the substrate,wherein the silicon carbide semiconductor device is provided with a semiconductor switching element with an inversion type switching element that forms an inversion type channel region on a surface portion of the base region located on a side surface of the trench by controlling an application voltage to the gate electrode, and allows a current to flow between the source electrode and the drain electrode through the source region and the drift layer.
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Accused Products
Abstract
In a silicon carbide semiconductor device, a p-type SiC layer is disposed in a corner of a bottom of a trench. Thus, even if an electric field is applied between a drain and a gate when a MOSFET is turned off, a depletion layer in a pn junction between the p-type SiC layer and an n− type drift layer greatly extends toward the n− type drift layer, and a high voltage caused by an influence of a drain voltage hardly enters a gate insulating film. Hence, an electric field concentration within the gate insulating film can be reduced, and the gate insulating film can be restricted from being broken. In this case, although the p-type SiC layer may be in a floating state, the p-type SiC layer is formed in only the corner of the bottom of the trench. Thus, the deterioration of the switching characteristic is relatively low.
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Citations
10 Claims
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1. A silicon carbide semiconductor device comprising:
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a first or second conductivity type substrate that is made of silicon carbide; a drift layer that is disposed on the substrate, and made of a first conductivity type silicon carbide lower in impurity concentration than the substrate; a base region that is disposed on the drift layer, and made of a second conductivity type silicon carbide; a source region that is disposed on the base region, and made of a first conductivity type silicon carbide higher in impurity concentration than the drift layer; a contact region that is connected to the base region, and made of a second conductivity type silicon carbide higher in impurity concentration than the base layer; a trench that extends to a position deeper than the base region from a surface of the source region; a second conductivity type layer that is disposed in a corner of a bottom of the trench, made of a second conductivity type silicon carbide, and has a triangular round shape in cross-section taken along a depth direction of the trench; a gate insulating film that is disposed on an inner wall surface of the trench on the second conductivity type layer; a gate electrode that is disposed on the gate insulating film within the trench; a source electrode that is electrically connected to the base region through the source region and the contact region; and a drain electrode that is disposed on a rear side of the substrate, wherein the silicon carbide semiconductor device is provided with a semiconductor switching element with an inversion type switching element that forms an inversion type channel region on a surface portion of the base region located on a side surface of the trench by controlling an application voltage to the gate electrode, and allows a current to flow between the source electrode and the drain electrode through the source region and the drift layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification