Trench power MOSFET with reduced on-resistance
First Claim
1. A semiconductor device comprising:
- a drift region of a first conductivity type;
a well region extending above the drift region and having a second conductivity type opposite the first conductivity type;
an active trench comprising sidewalls and a bottom, the active trench extending through the well region and into the drift region and having at least portions of its sidewalls and bottom lined with dielectric material;
a first shield disposed within the active trench and separated from the sidewalls of the active trench by the dielectric material;
a gate disposed within the active trench above the first shield and separated therefrom by inter-electrode dielectric material, the gate being separated from the sidewalls of the active trench by the dielectric material; and
source regions having the first conductivity type formed in the well region adjacent the active trench, wherein the first shield and the gate are made of materials having different work functions.
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Accused Products
Abstract
A semiconductor device includes a drift region, a well region extending above the drift region, an active trench including sidewalls and a bottom, the active trench extending through the well region and into the drift region and having at least portions of its sidewalls and bottom lined with dielectric material. The device further includes a shield disposed within the active trench and separated from the sidewalls of the active trench by the dielectric material, a gate disposed within the active trench above the first shield and separated therefrom by inter-electrode dielectric material, and source regions formed in the well region adjacent the active trench. The gate is separated from the sidewalls of the active trench by the dielectric material. The shield and the gate are made of materials having different work functions.
32 Citations
30 Claims
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1. A semiconductor device comprising:
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a drift region of a first conductivity type; a well region extending above the drift region and having a second conductivity type opposite the first conductivity type; an active trench comprising sidewalls and a bottom, the active trench extending through the well region and into the drift region and having at least portions of its sidewalls and bottom lined with dielectric material; a first shield disposed within the active trench and separated from the sidewalls of the active trench by the dielectric material; a gate disposed within the active trench above the first shield and separated therefrom by inter-electrode dielectric material, the gate being separated from the sidewalls of the active trench by the dielectric material; and source regions having the first conductivity type formed in the well region adjacent the active trench, wherein the first shield and the gate are made of materials having different work functions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A semiconductor device comprising:
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a drift region of an epitaxially grown P-type conductivity material; a well region extending above the drift region and having an n-type conductivity material; an active trench comprising sidewalls and a bottom, the active trench extending through the well region and into the drift region, the active trench having at least portions of its sidewalls and bottom lined with dielectric material; a first shield disposed within the active trench and separated from the sidewalls of the active trench by the dielectric material, the first shield comprising an N-type polysilicon material; a gate disposed within the active trench above the first shield and separated therefrom by inter-electrode dielectric material, the gate being separated from the sidewalls of the active trench by the dielectric material, the gate comprises a material different than the first shield material; and source regions having a P-type conductivity formed in the well region adjacent the active trench. - View Dependent Claims (20, 21, 22, 23)
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24. A method of forming a semiconductor device comprising:
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forming a drift region of a first conductivity type; forming an active trench extending through a well region and into the drift region, the active trench comprising sidewalls and a bottom; lining portions of sidewalls of the active trench and a bottom of the active trench with a dielectric material; forming a shield comprising an N-type polysilicon material within the active trench and separated from the sidewalls of the active trench by the dielectric material; forming an inter-electrode dielectric material over the shield in the active trench; forming a well region extending above the drift region, the well region having a second conductivity type opposite the first conductivity type; forming a gate within the active trench above the shield and separated therefrom by the inter-electrode dielectric material, the gate being separated from the sidewalls of the active trench by the dielectric material, the gate comprises a material different than the shield material; and forming source regions in the well region adjacent the active trench, the source regions having the first conductivity type. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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Specification