Schottky barrier rectifier with MOS trench
First Claim
1. A semiconductor rectifier comprising:
- a semiconductor substrate having first and second opposing faces, said substrate having a cathode region of first conductivity type extending to said first face and a drift region of said first conductivity type extending to said second face, said drift region having a predetermined drift region doping concentration;
a cathode electrode on said first face, ohmically contacting said cathode region;
an anode electrode on said second face, said anode electrode forming a Schottky rectifying junction with said drift region at said second face; and
means, in said drift region, for increasing the reverse blocking voltage of said Schottky rectifying junction above the reverse blocking voltage of an ideal parallel-plane abrupt P-N junction
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Abstract
A trench MOS Schottky barrier rectifier includes a semiconductor substrate having first and second faces, a cathode region of first conductivity type at the first face and a drift region of first conductivity type on the cathode region, extending to the second face. First and second trenches are formed in the drift region at the second face and define a mesa of first conductivity type therebetween. The mesa can be rectangular or circular in shape or of stripe geometry. Insulating regions are defined on the sidewalls of the trenches, adjacent the mesa, and an anode electrode is formed on the insulating regions, and on the top of the mesa at the second face. The anode electrode forms a Schottky rectifying contact with the mesa. The magnitude of reverse-biased leakage currents in the mesa and the susceptibility to reverse breakdown are limited not only by the potential barrier formed by the rectifying contact but also by the potential difference between the mesa and the portion of anode electrode extending along the insulating regions. Moreover, by properly choosing the width of the mesa, and by doping the mesa to a concentration greater than about 1×1016 per cubic centimeters, reverse blocking voltages greater than those of a corresponding parallel-plane P-N junction rectifier can be achieved.
275 Citations
18 Claims
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1. A semiconductor rectifier comprising:
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a semiconductor substrate having first and second opposing faces, said substrate having a cathode region of first conductivity type extending to said first face and a drift region of said first conductivity type extending to said second face, said drift region having a predetermined drift region doping concentration; a cathode electrode on said first face, ohmically contacting said cathode region; an anode electrode on said second face, said anode electrode forming a Schottky rectifying junction with said drift region at said second face; and means, in said drift region, for increasing the reverse blocking voltage of said Schottky rectifying junction above the reverse blocking voltage of an ideal parallel-plane abrupt P-N junction - View Dependent Claims (2, 3, 4)
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5. A semiconductor rectifier comprising:
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a semiconductor substrate having first and second opposing faces, said substrate having a cathode region of first conductivity type extending to said first face and a drift region of said first conductivity type extending to said second face; a cathode electrode on said first face, ohmically contacting said cathode region; a first trench in said drift region at said second face, said first trench having a first sidewall in said drift region; a second trench in said drift region adjacent said first trench, said second trench having a second sidewall in said drift region, adjacent said first sidewall, said first and second sidewalls defining a mesa in said drift region, having a predetermined mesa width from said first sidewall to said second sidewall and having a predetermined mesa doping concentration; first and second insulating regions on said first sidewall and said second sidewall, respectively; and an anode electrode on said second face and on said first and said second insulating regions, said anode electrode forming a rectifying contact with said mesa at said second face; wherein said predetermined mesa doping concentration is greater than 1×
1016 dopants per cubic centimeter; andwherein the product of said predetermined mesa doping concentration and said predetermined mesa width is less than or equal to 5×
1012 per square centimeter. - View Dependent Claims (6, 7, 8, 9)
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10. A semiconductor rectifier comprising:
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a semiconductor substrate having first and second opposing faces, said substrate having a cathode region of first conductivity type extending to said first face; a cathode electrode on said first face, ohmically contacting said cathode region; a first trench in said substrate at said second face, said first trench having a first sidewall in said substrate; a second trench in said substrate adjacent said first trench, said second trench having a second sidewall in said substrate, adjacent said first sidewall, said first and second sidewalls defining a mesa in said substrate, said mesa extending to said second face and having a predetermined mesa width from said first sidewall to said second sidewall; a drift region of said first conductivity type in said substrate, extending between said cathode region and said second face and between said first and said second sidewalls, said drift region having a predetermined drift region doping concentration; first and second insulating regions on said first sidewall and said second sidewall, respectively; and an anode electrode on said second face and on said first and said second insulating regions, said anode electrode forming a rectifying contact with said mesa at said second face; wherein said predetermined drift region doping concentration is greater than 1×
1016 dopants per cubic centimeter; andwherein the product of said predetermined drift region doping concentration and said predetermined mesa width is less than or equal to 5×
1012 per square centimeter. - View Dependent Claims (11, 12, 13, 14)
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15. A semiconductor rectifier comprising:
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a semiconductor substrate of first conductivity type having first and second opposing faces; a first trench in said substrate at said second face, said first trench having a first sidewall; a second trench in said substrate adjacent said first trench, said second trench having a second sidewall, adjacent said first sidewall, said first and second sidewalls defining a mesa having a predetermined mesa width from said first sidewall to said second sidewall and having a predetermined mesa doping concentration; first and second insulating regions on said first sidewall and said second sidewall, respectively; and an anode electrode on said second face and on said first and said second insulating regions, said anode electrode forming a rectifying contact with said mesa at said second face; wherein said predetermined mesa doping concentration is greater than 1×
1016 dopants per cubic centimeter; andwherein the product of said predetermined mesa doping concentration and said predetermined mesa width is less than or equal to 5×
1012 per square centimeter. - View Dependent Claims (16, 17, 18)
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Specification