POWER SEMICONDUCTOR DEVICE STRUCTURE FOR INTEGRATED CIRCUIT AND METHOD OF FABRICATION THEREOF
First Claim
1. A trench-gate semiconductor device comprising:
- a semiconductor substrate having a first major surface;
a trench extending from the first major surface (3) into the substrate;
first and second impurity doped regions of a first conductivity type at respective first and second opposing sides of the trench adjacent the first major surface;
a body region of a second conductivity type, opposite to the first conductivity type, formed only below the first impurity doped region on the first side of the trench;
a drift region of the first conductivity type, below the body region and the second impurity doped region, the trench terminating in the drift region;
a conductive gate insulated from the body region by a gate insulator, anda conductive field plate in the trench, the field plate extending into the trench parallel to the conductive gate to depth greater than or equal to the depth of the conductive gate, wherein the field plate is insulated from the drift region in the trench by a field plate insulating layer, and wherein the thickness of the field plate insulating layer is substantially greater than the thickness of the gate insulator.
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Abstract
A power semiconductor device comprises a conductive gate, provided in an upper part of a trench (11) formed in a semiconductor substrate (1), and a conductive field plate, extending in the trench, parallel to the conductive gate, to a depth greater that the conductive gate. The field plate is insulated from the walls and bottom of the trench by a field plate insulating layer that is thicker than the gate insulating layer. In one embodiment, the field plate is insulated within the trench from the gate. Impurity doped regions of a first conductivity type are provided at the surface of the substrate adjacent the first and second sides of the trench and form source and drain regions, and a body region (7) of second conductivity type is formed under the source region on the first side of the trench (11). The conductive gate is insulated from the body region (7) by a gate insulating layer. A method of making the semiconductor device is compatible with conventional CMOS processes.
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Citations
13 Claims
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1. A trench-gate semiconductor device comprising:
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a semiconductor substrate having a first major surface; a trench extending from the first major surface (3) into the substrate; first and second impurity doped regions of a first conductivity type at respective first and second opposing sides of the trench adjacent the first major surface; a body region of a second conductivity type, opposite to the first conductivity type, formed only below the first impurity doped region on the first side of the trench; a drift region of the first conductivity type, below the body region and the second impurity doped region, the trench terminating in the drift region; a conductive gate insulated from the body region by a gate insulator, and a conductive field plate in the trench, the field plate extending into the trench parallel to the conductive gate to depth greater than or equal to the depth of the conductive gate, wherein the field plate is insulated from the drift region in the trench by a field plate insulating layer, and wherein the thickness of the field plate insulating layer is substantially greater than the thickness of the gate insulator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for making a semiconductor device, comprising:
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forming a trench in a first major surface of a semiconductor substrate, the trench having first and second opposing sides; lining the trench with a first insulating layer having a first thickness; filling the trench with a conductive material; forming first and second impurity doped regions of a first conductivity type adjacent the first major surface at the respective first and second sides of the trench; forming a body region of a second conductivity type, opposite to the first conductivity type, only on the first side of the trench, the body region extending to a first predetermined depth from the first major surface. forming a sub-trench extending to a second predetermined depth from the first major surface and having a first sidewall adjacent the body region; lining the first sidewall of the sub-trench with a second insulating layer having a second thickness, which is substantially less that the first thickness, and filling the sub-trench with a conductive material. - View Dependent Claims (10, 11, 12, 13)
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Specification