POWER MOSFET AND METHOD OF FABRICATING THE SAME
First Claim
1. A power MOSFET, comprising:
- a substrate of a first conductivity type;
an epitaxial layer of the first conductivity type, disposed on the substrate;
a body layer of a second conductivity type, disposed in the epitaxial layer, wherein the body layer has a first trench therein, the epitaxial layer has a second trench therein, the second trench is disposed below the first trench, and a width of the second trench is much smaller than a width of the first trench;
a first insulating layer, at least disposed in the second trench;
a first conductive layer, disposed in the first trench;
a second insulating layer, at least disposed between a sidewall of the first trench and the first conductive layer; and
two source regions of the first conductivity type, disposed in the body layer beside the first trench respectively.
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Accused Products
Abstract
A power MOSFET including a substrate of first conductivity type, an epitaxial layer of first conductivity type on the substrate, a body layer of second conductivity type in the epitaxial layer, a first insulating layer, a second insulating layer, a first conductive layer and two source regions of first conductivity type is provided. The body layer has a first trench therein. The epitaxial layer has a second trench therein. The second trench is below the first trench, and the width of the second trench is much smaller than that of the first trench. The first insulating layer is at least in the second trench. The first conductive layer is in the first trench. The second insulating layer is at least between the sidewall of the first trench and the first conductive layer. The source regions are disposed in the body layer beside the first trench respectively.
17 Citations
20 Claims
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1. A power MOSFET, comprising:
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a substrate of a first conductivity type; an epitaxial layer of the first conductivity type, disposed on the substrate; a body layer of a second conductivity type, disposed in the epitaxial layer, wherein the body layer has a first trench therein, the epitaxial layer has a second trench therein, the second trench is disposed below the first trench, and a width of the second trench is much smaller than a width of the first trench; a first insulating layer, at least disposed in the second trench; a first conductive layer, disposed in the first trench; a second insulating layer, at least disposed between a sidewall of the first trench and the first conductive layer; and two source regions of the first conductivity type, disposed in the body layer beside the first trench respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of fabricating a power MOSFET, comprising:
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forming an epitaxial layer of a first conductivity type on the substrate of the first conductivity type; forming a first trench in the epitaxial layer; forming a second trench below the first trench, wherein a width of the second trench is smaller than a width of the first trench; forming a first insulating layer to at least fill up the second trench; forming a second insulating layer at least on a sidewall of the first trench; forming a first conductive layer in the first trench; forming a body layer of a second conductivity type in the epitaxial layer around the first trench; and forming two source regions of the first conductivity type in the body layer beside the first trench. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification