Silicon carbide power MOSFET with floating field ring and floating field plate
First Claim
1. A power device comprising:
- a silicon carbide substrate of first conductivity type, having first and second opposing faces and including a device region extending from said first face to said second face, and a termination region extending from said first face to said second face;
a first silicon carbide layer of second conductivity type on said first face, extending over said device region and said termination region;
a second silicon carbide layer of said first conductivity type on said first silicon carbide layer, extending over said device region;
a power field effect transistor in said device region of said silicon carbide substrate and in said first and second silicon carbide layers thereover; and
a first termination trench in said termination region of said silicon carbide substrate, and extending through said first silicon carbide layer thereover, to define a mesa of said first silicon carbide layer over said termination region.
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Accused Products
Abstract
A silicon carbide power MOSFET device includes a first silicon carbide layer, epitaxially formed on the silicon carbide substrate of opposite conductivity type. A second silicon carbide layer of the same conductivity type as the substrate is formed on the first silicon carbide layer. A power field effect transistor is formed in the device region of the substrate and in the first and second silicon carbide layers thereover. At least one termination trench is formed in the termination region of the silicon carbide substrate, extending through the first and second silicon carbide layers thereover. The termination trench defines one or more isolated mesas in the termination region which act as floating field rings. The termination trenches are preferably insulator lined and filled with conductive material to form floating field plates. The outermost trench may be a deep trench which extends through the first and second silicon carbide layers and through the drift region of the silicon carbide substrate. Since the termination region is formed from the first and second silicon carbide layers in the termination region, a time consuming, high temperature diffusion to form a floating field ring is not necessary. Rather, the same epitaxial first and second silicon carbide layers which are used to form an FET in the device region may also be used to form the floating field ring in the termination region.
283 Citations
24 Claims
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1. A power device comprising:
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a silicon carbide substrate of first conductivity type, having first and second opposing faces and including a device region extending from said first face to said second face, and a termination region extending from said first face to said second face; a first silicon carbide layer of second conductivity type on said first face, extending over said device region and said termination region; a second silicon carbide layer of said first conductivity type on said first silicon carbide layer, extending over said device region; a power field effect transistor in said device region of said silicon carbide substrate and in said first and second silicon carbide layers thereover; and a first termination trench in said termination region of said silicon carbide substrate, and extending through said first silicon carbide layer thereover, to define a mesa of said first silicon carbide layer over said termination region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A power device comprising:
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a silicon carbide substrate of first conductivity type, having first and second opposing faces and including a device region extending from said first face to said second face, and a termination region extending from said first face to said second face; a first silicon carbide layer of second conductivity type on said first face, extending over said termination region; a power field effect transistor in said device region of said silicon carbide substrate; and a first termination trench in said termination region of said silicon carbide substrate, said first termination trench extending through said first silicon carbide layer and being lined with insulating material, and containing a conductive material therein. - View Dependent Claims (16, 17, 18)
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19. A power device comprising:
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a silicon carbide substrate of first conductivity type, having first and second opposing faces and including a device region extending from said first face to said second face, and a termination region extending from said first face to said second face; a first silicon carbide layer of second conductivity type on said first face, extending over said device region; a second silicon carbide layer of said first conductivity type on said first silicon carbide layer, extending over said device region; a power field effect transistor in said device region of said silicon carbide substrate and in said first and second silicon carbide layers thereover; and a first termination trench in said termination region of said silicon carbide substrate, said first termination trench being lined with insulating material, and containing a conductive material therein; wherein said silicon carbide substrate includes a lightly doped region of said first conductivity type adjacent said first face, and a heavily doped region of said first conductivity type adjacent said second face, and wherein said power device further comprises a deep termination trench in said termination region of said silicon carbide substrate, which extends through said lightly doped region, said deep termination trench being lined with insulating material and containing a conductive material therein.
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20. A power device comprising:
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a silicon carbide substrate of first conductivity type, having first and second opposing faces and including a device region extending from said first face to said second face, and a termination region extending from said first face to said second face; a first silicon carbide layer of second conductivity type on said first face, extending over said device region and said termination region; a second silicon carbide layer of said first conductivity type on said first silicon carbide layer, extending over said device region and said termination region; a power field effect transistor in said device region of said silicon carbide substrate and in said first and second silicon carbide layers thereover; and a first termination trench in said termination region of said silicon carbide substrate, extending through said first silicon carbide layer and said second silicon carbide layer thereover, to define a mesa of said first silicon carbide layer and said second silicon carbide layer over said termination region, said first termination trench being lined with insulating material, and containing a conductive material therein, said conductive material being electrically isolated from said power field effect transistor. - View Dependent Claims (21, 22, 23, 24)
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Specification