High-voltage vertical transistor with a multi-gradient drain doping profile
First Claim
1. A high-voltage transistor comprising:
- a drain region of a first conductivity type;
a source region of the first conductivity type;
a body region of a second conductivity type opposite to the first conductivity type, the body region adjoining the source region;
a drift region of the first conductivity type extending in a first direction from the drain region to the body region, the drift region comprising first and second sections, each disposed below the body region and each having substantially different first and second doping concentration gradients, respectively, the first doping concentration gradient being less than the second doping concentration gradient the first section being nearest the source region and the second section being nearest the drain region;
first and second field plate members respectively disposed on opposite sides of the drift region, the first and second field plate members being fully insulated from the drift region; and
an insulated gate disposed adjacent the body region.
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Accused Products
Abstract
A high-voltage transistor includes first and second trenches that define a mesa in a semiconductor substrate. First and second field plate members are respectively disposed in the first and second trenches, with each of the first and second field plate members being separated from the mesa by a dielectric layer. The mesa includes a plurality of sections, each section having a substantially constant doping concentration gradient, the gradient of one section being at least 10% greater than the gradient of another section. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).
190 Citations
28 Claims
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1. A high-voltage transistor comprising:
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a drain region of a first conductivity type; a source region of the first conductivity type; a body region of a second conductivity type opposite to the first conductivity type, the body region adjoining the source region; a drift region of the first conductivity type extending in a first direction from the drain region to the body region, the drift region comprising first and second sections, each disposed below the body region and each having substantially different first and second doping concentration gradients, respectively, the first doping concentration gradient being less than the second doping concentration gradient the first section being nearest the source region and the second section being nearest the drain region; first and second field plate members respectively disposed on opposite sides of the drift region, the first and second field plate members being fully insulated from the drift region; and an insulated gate disposed adjacent the body region.
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2. A high-voltage transistor comprising:
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a drain region of a first conductivity type; a source region of the first conductivity type; a body region of a second conductivity type opposite to the first conductivity type, the body region adjoining the source region; a drift region of the first conductivity type extending in a first direction from the drain region to the body region, the drift region comprising first and second sections, each disposed below the body region and each having substantially different first and second doping concentration gradients, respectively the first doping concentration gradient being less than the second doping concentration;
the first section being nearest the source region and the second section being nearest the drain region,first and second field plate members respectively disposed on opposite sides of the drift region, the first and second field plate members each being insulated from the drift region by a dielectric layer, the drift region and the dielectric layer each having a width in a second direction orthogonal to the first direction, the width of the dielectric layer being greater than the width of the drift region; and an insulated gate disposed adjacent the body region.
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3. A high-voltage transistor comprising:
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a drain of a first conductivity type; a source of the first conductivity type; a drift region of the first conductivity type extending in a first direction from the drain to the source, and comprising first and second sections having substantially different first and second doping concentration gradients, respectively, the first doping concentration gradient having a lowest doping concentration at a point in the first section nearest the source, with the first doping concentration gradient being lower than the second doping concentration gradient; and first and second field plate members respectively disposed on opposite sides of the drift region, each of the field plate members being insulated from the drift region by a dielectric layer. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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11. A high-voltage transistor comprising:
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a substrate; first and second trenches in the substrate that define a mesa; first and second field plate members respectively disposed in the first and second trenches, each of the first and second field plate members being separated from the mesa by a dielectric layer; and wherein the mesa comprises a plurality of sections, each section having a substantially linear doping concentration gradient, an uppermost section having a doping concentration gradient that is at least 10% lower than a doping concentration gradient of a lowermost section. - View Dependent Claims (12)
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13. A high-voltage transistor comprising:
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a drain of a first conductivity type; a source of the first conductivity type; a body region of a second conductivity type opposite to the first conductivity type, the body region adjoining the source region; a drift region of the first conductivity type extending in a vertical direction from the drain region to the body region, the drift region comprising first, second, and third sections, the first section being nearest the body region and the third region being farthest from the body region, the first section having a substantially constant doping concentration, the second section having a first doping concentration gradient with a lowest doping concentration level nearest the first section, and the third section having a second doping concentration gradient at least 10% higher that the first doping concentration gradient; first and second field plate members respectively disposed on opposite sides of the drift region, the first and second field plate members being fully insulated from the drift region; and an insulated gate disposed adjacent the body region. - View Dependent Claims (14, 15, 16)
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17. A high-voltage transistor comprising:
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a drain of a first conductivity type; a source of the first conductivity type; a drift region of the first conductivity type extending in a vertical direction from the drain to the source, the drift region comprising first and second sections having substantially different first and second doping concentration gradients, respectively, the first section being disposed near the source with the second section being disposed directly beneath the first section, the first section having a lowest doping concentration nearest the source and a highest doping concentration nearest the second section, the second section having a lowest doping concentration nearest the first section, the highest doping concentration of the first section being substantially equal to the lowest doping concentration of the second section, and the first doping concentration gradient being less than the second doping concentration gradient; and first and second field plate members respectively disposed on opposite sides of the drift region, each of the field plate members being insulated from the drift region by a dielectric layer. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A high-voltage transistor comprising:
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a drain of a first conductivity type; a source of the first conductivity type; a drift region of the first conductivity type extending in a first direction from the drain to the source, and comprising first and second sections having first and second doping concentration gradients, respectively, the first section being disposed a first vertical distance below the source and having a lowest doping concentration nearest the source and a highest doping concentration farthest from the source, the second section being disposed beneath the first section and having a lowest doping concentration nearest the first section and a highest doping concentration farthest from the first section, the highest doping concentration of the first section being substantially the same as the lowest doping concentration of the second section; and first and second field plate members respectively disposed on opposite sides of the drift region, each of the field plate members being insulated from the drift region by a dielectric layer. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification