Apparatus and method for power MOS transistor
First Claim
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1. A method comprising:
- forming an n-type buried layer over a p-type substrate;
forming an n-type epitaxial layer over the n-type buried layer;
forming a first trench and a second trench through the n-type epitaxial layer and partially through the n-type buried layer, wherein a width of the second trench is greater than a width of the first trench;
forming a dielectric region in the first trench, wherein a top surface of the dielectric region is higher than a top surface of the n-type buried layer, and a bottom surface of the dielectric region is lower than the top surface of the n-type buried layer;
forming a first gate region in the first trench and a second gate region in the second trench, wherein the first gate region is over the dielectric region; and
forming a source region and a drain region on opposite sides of the first trench, wherein the drain region is between the first trench and the second trench.
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Abstract
A method comprises forming a buried layer over a substrate, forming an epitaxial layer over the buried layer, forming a first trench and a second trench in the buried layer and the epitaxial layer, wherein a width of the second trench is greater than a width of the first trench, depositing a dielectric layer in the first trench and the second trench, wherein the dielectric layer partially fills the second trench, removing the dielectric layer in the second trench and forming a first gate region in the first trench and a second gate region in the second trench.
46 Citations
20 Claims
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1. A method comprising:
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forming an n-type buried layer over a p-type substrate; forming an n-type epitaxial layer over the n-type buried layer; forming a first trench and a second trench through the n-type epitaxial layer and partially through the n-type buried layer, wherein a width of the second trench is greater than a width of the first trench; forming a dielectric region in the first trench, wherein a top surface of the dielectric region is higher than a top surface of the n-type buried layer, and a bottom surface of the dielectric region is lower than the top surface of the n-type buried layer; forming a first gate region in the first trench and a second gate region in the second trench, wherein the first gate region is over the dielectric region; and forming a source region and a drain region on opposite sides of the first trench, wherein the drain region is between the first trench and the second trench. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method comprising:
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forming a buried layer over a substrate; forming an epitaxial layer over the buried layer; depositing a dielectric layer over the epitaxial layer; depositing a hard mask layer over the dielectric layer; forming a first trench and a second trench through patterning the hard mask layer and the dielectric layer, wherein the first trench and the second trench are through the epitaxial layer and partially through the buried layer; forming a dielectric region in the first trench, wherein a top surface of the dielectric region is higher than a top surface of the buried layer; and forming a first gate region in the first trench and a second gate region in the second trench, wherein the first gate region is over the dielectric region. - View Dependent Claims (12, 13, 14, 15)
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16. A method comprising:
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forming a buried layer over a substrate; forming an epitaxial layer over the buried layer; forming a first trench and a second trench in the buried layer and the epitaxial layer, wherein a width of the second trench is greater than a width of the first trench; depositing a dielectric layer in the first trench and the second trench, wherein the dielectric layer partially fills the second trench; removing the dielectric layer in the second trench; and forming a first gate region in the first trench and a second gate region in the second trench. - View Dependent Claims (17, 18, 19, 20)
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Specification