Power MOSFET having enhanced breakdown voltage
First Claim
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1. A power metal oxide semiconductor field effect transistor (MOSFET), comprising:
- a source region;
a drain region;
a gate;
a body region;
a drift region extending between said body region and drain region, to at least partially guide current from said drain region to said source region;
a dielectric having opposing sides, one of its opposing sides extending alongside said drift region, and an opposite one of its opposing sides connected to a conducting region, so that a voltage across said dielectric between its opposing sides exerts an electric field into said drift region to redistribute free carriers in said drift region and thereby affect the electrical field distribution in said drift region to increase the breakdown voltage of a reverse biased semiconductor junction between said drift region and said body region.
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Abstract
A MOSFET includes a dielectric, preferably in the form of a metal thick oxide that extends alongside the MOSFET'"'"'s drift region. A voltage across this dielectric between its opposing sides exerts an electric field into the drift region to modulate the drift region electric field distribution so as to increase the breakdown voltage of a reverse biased semiconductor junction between the drift region and body region. This allows for higher doping of the drift region, for a given breakdown voltage when compared to conventional MOSFETs.
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Citations
25 Claims
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1. A power metal oxide semiconductor field effect transistor (MOSFET), comprising:
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a source region;
a drain region;
a gate;
a body region;
a drift region extending between said body region and drain region, to at least partially guide current from said drain region to said source region;
a dielectric having opposing sides, one of its opposing sides extending alongside said drift region, and an opposite one of its opposing sides connected to a conducting region, so that a voltage across said dielectric between its opposing sides exerts an electric field into said drift region to redistribute free carriers in said drift region and thereby affect the electrical field distribution in said drift region to increase the breakdown voltage of a reverse biased semiconductor junction between said drift region and said body region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25)
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13. A method of forming a metal oxide semiconductor transistor (MOSFET) in a semiconductor wafer comprising:
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forming opposed vertically extending trenches in said semiconductor wafer;
covering interior walls of each of said trenches with a dielectric material of a defined thickness;
filling a volume of each of said trenches between said dielectric material with a conductive material;
forming a double diffused MOSFET structure between said opposed vertical trenches, said MOSFET structure formed to have a drift region that abuts said dielectric material along at least a portion of its vertical extent.
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23. A n-channel or p-channel power metal oxide semiconductor field effect transistor (MOSFET), comprising:
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a source region;
a drain region;
a gate;
a body region;
a drift region extending between said body region and drain region, to at least partially guide current from said source region to said drain region;
two dielectric columns each having opposing sides, one opposing side of each of said two dielectric columns extending alongside said drift region, and an opposite one of said opposing sides of each of said dielectric columns electrically connected to a conducting region, so that a voltage across each of said two dielectric columns between its opposing sides exerts an electric field into said drift region to redistribute free carriers in said drift region and thereby affect the electrical field distribution in said drift region to increase the breakdown voltage of a reverse biased semiconductor junction between said drift region and said body region.
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Specification