Method of manufacturing a closed cell trench MOSFET
First Claim
1. A method of fabricating a closed cell trench metal-oxide-semiconductor field effect transistor (TMOSFET) comprising:
- depositing a first semiconductor layer upon a substrate, wherein said first semiconductor layer is doped with a first type of impurity;
etching a plurality of trenches in said first semiconductor layer, wherein a first set of said plurality of trenches are substantially parallel with respect to each other and a second set of said plurality of trenches are substantially normal-to-parallel with respect to said first set of said plurality of trenches;
forming a dielectric proximate said plurality of trenches;
doping said first semiconductor layer proximate the bottoms of said first set of said plurality of trenches with said first type of impurity;
doping said first semiconductor layer proximate the bottoms of said second set of said plurality of trenches with a second type of impurity;
depositing a second semiconductor layer in said plurality of trenches;
doping a first portion of said first semiconductor layer with said second type of impurity, wherein the first portion of said first semiconductor layer extends below said plurality of trenches; and
doping a second portion of said first semiconductor layer proximate said dielectric with said first type of impurity.
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Accused Products
Abstract
Embodiments of the present invention provide an improved closed cell trench metal-oxide-semiconductor field effect transistor (TMOSFET). The closed cell TMOSFET comprises a drain, a body region disposed above the drain region, a gate region disposed in the body region, a gate insulator region, a plurality of source regions disposed at the surface of the body region proximate to the periphery of the gate insulator region. A first portion of the gate region and the gate oxide region are formed as parallel elongated structures. A second portion of the gate region and the oxide region are formed as normal-to-parallel elongated structures. A portion of the gate and drain overlap region are selectively blocked by the body region, resulting in lower overall gate to drain capacitance.
70 Citations
16 Claims
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1. A method of fabricating a closed cell trench metal-oxide-semiconductor field effect transistor (TMOSFET) comprising:
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depositing a first semiconductor layer upon a substrate, wherein said first semiconductor layer is doped with a first type of impurity; etching a plurality of trenches in said first semiconductor layer, wherein a first set of said plurality of trenches are substantially parallel with respect to each other and a second set of said plurality of trenches are substantially normal-to-parallel with respect to said first set of said plurality of trenches; forming a dielectric proximate said plurality of trenches; doping said first semiconductor layer proximate the bottoms of said first set of said plurality of trenches with said first type of impurity; doping said first semiconductor layer proximate the bottoms of said second set of said plurality of trenches with a second type of impurity; depositing a second semiconductor layer in said plurality of trenches; doping a first portion of said first semiconductor layer with said second type of impurity, wherein the first portion of said first semiconductor layer extends below said plurality of trenches; and doping a second portion of said first semiconductor layer proximate said dielectric with said first type of impurity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of fabricating a closed cell trench metal-oxide semiconductor field effect transistor (TMOSFEET) comprising:
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depositing a first portion of a first semiconductor layer upon a substrate, wherein said first semiconductor layer is doped with a first type of impurity; doping said first portion of said first semiconductor layer, wherein a plurality of buried doped regions are formed in said first portion of said first semiconductor layer; depositing a second portion of said first semiconductor layer upon said first portion of said first semiconductor layer; etching a plurality of trenches in said first semiconductor layer, wherein a first set of said plurality of trenches are substantially parallel with respect to each other and said plurality of buried doped regions are aligned proximate the bottom of said first set of said plurality of trenches, and wherein a second set of said plurality of trenches are substantially normal-to-parallel with respect to said first set of said plurality of trenches; doping said first semiconductor layer aligned proximate the bottoms of said second set of said plurality of trenches with an impurity type opposite said plurality of buried doped regions; forming a dielectric proximate said plurality of trenches; depositing a second semiconductor layer in said plurality of trenches; doping a body region of said first semiconductor layer between said plurality of trenches with a second type of impurity; and doping a source region of said first semiconductor layer between said plurality of trenches and said first region of said first semiconductor layer. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification