Bidirectional blocking accumulation-mode trench power MOSFET
First Claim
1. An accumulation-mode MOSFET comprising:
- a semiconductor chip;
a gate formed in a trench at a surface of said semiconductor chip and separated from said semiconductor chip by an insulating layer, said trench defining a cell of said MOSFET, a first region of said semiconductor chip being located within said cell and containing semiconductor material of a first conductivity type, said cell being designed such that a substantial portion of said first region is depleted thereby preventing the flow of current through said first region when said gate is held at a predetermined voltage;
a second region of said first conductivity type located under said trench;
a third region of a second conductivity type adjacent said second region, a junction between said second and third regions forming a first diode; and
a fourth region of said first conductivity type adjacent said third region, a junction between said third and fourth regions forming a second diode, wherein said fourth region is connected to said gate.
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Accused Products
Abstract
One or more diodes are integrated with a trenched gate accumulation-mode MOSFET to provide protection for the gate oxide layer. In a preferred embodiment, a first pair of diodes are formed in a series connection between the source and the gate of the MOSFET. A third diode may be added to provide a series diode pair between the drain and the gate of the MOSFET. A pair of accumulation-mode MOSFETs may be formed in a single chip to provide a push-pull halfbridge circuit, and a multiple-phase motor driver may be fabricated in two chips, with the high side MOSFETs being formed in one chip and the low side MOSFETs being formed in the other chip. The accumulation-mode MOSFET may be used as an AC switch by connecting its gate to a gate bias circuit which finds the lower of the source and drain voltages of the accumulation-mode MOSFET.
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Citations
36 Claims
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1. An accumulation-mode MOSFET comprising:
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a semiconductor chip; a gate formed in a trench at a surface of said semiconductor chip and separated from said semiconductor chip by an insulating layer, said trench defining a cell of said MOSFET, a first region of said semiconductor chip being located within said cell and containing semiconductor material of a first conductivity type, said cell being designed such that a substantial portion of said first region is depleted thereby preventing the flow of current through said first region when said gate is held at a predetermined voltage; a second region of said first conductivity type located under said trench; a third region of a second conductivity type adjacent said second region, a junction between said second and third regions forming a first diode; and a fourth region of said first conductivity type adjacent said third region, a junction between said third and fourth regions forming a second diode, wherein said fourth region is connected to said gate. - View Dependent Claims (2, 27, 28, 29, 30)
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4. An accumulation-mode field-effect transistor (MOSFET) comprising:
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a semiconductor material; a gate positioned in a trench at a surface of said semiconductor material and separated from said semiconductor material by a gate insulating layer, said trench defining a transistor cell, said cell containing substantially only material of a first conductivity type; a first heavily-doped region of said first conductivity type located at a surface of said cell; a lightly-doped region of said first conductivity type adjacent said heavily-doped region; a first PN junction within said semiconductor material, said first PN junction forming a first diode; and a second PN junction within said semiconductor material, said second PN junction forming a second diode, said first and second diodes being connected in series between said heavily doped region and said gate. - View Dependent Claims (3, 5, 6)
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7. A halfbridge circuit formed in a semiconductor chip, said halfbridge circuit comprising:
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a first accumulation-mode MOSFET, said first accumulation-mode MOSFET comprising a first trenched gate, a first heavily-doped region of a first conductivity type located at a surface of said chip, a second lightly-doped region of said first conductivity type located below said first region, and a third heavily-doped region of said first conductivity type located below said second lightly-doped region; a second accumulation-mode MOSFET, said second accumulation-mode MOSFET comprising a second trenched gate, a fourth heavily-doped region of said first conductivity type located at a surface of said chip, a fifth lightly-doped region of said first conductivity type located below said fourth region, and said third heavily-doped region of said first conductivity type; a first voltage supply connected to said first heavily-doped region and a second voltage supply connected to said fourth heavily-doped region; and an output terminal connected to said third heavily-doped region. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A multiple-phase motor driver comprising:
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a first chip, said first chip comprising a plurality of high side accumulation-mode MOSFETs; and a second chip, said second chip comprising a plurality of low side accumulation-mode MOSFETs; wherein a substrate of said first chip is connected to a first voltage source and a substrate of said second chip is connected to a second voltage source, and wherein a first MOSFET in said first chip is connected to a first MOSFET in said second chip and to a first output terminal, and a second MOSFET in said first chip is connected to a second MOSFET in said second chip and to a second output terminal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. An accumulation-mode MOSFET comprising:
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a semiconductor chip of a first conductivity type; a trenched gate formed in said chip, said gate defining a MOSFET cell, said gate comprising a first region doped with a dopant of said first conductivity type, a second region adjacent said first region and doped with a dopant of a second conductivity type, and a third region adjacent said second region and doped with a dopant of said first conductivity type; wherein said third region is connected to a surface of said MOSFET cell. - View Dependent Claims (25)
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26. An accumulation-mode MOSFET comprising:
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a semiconductor chip of a first conductivity type; a trenched gate formed in said chip, said gate defining a MOSFET cell, said gate comprising a first region doped with a dopant of said first conductivity type, a second region adjacent said first region and doped with a dopant of a second conductivity type, and a third region adjacent said second region and doped with a dopant of said first conductivity type; wherein said third region is connected to a backside of said semiconductor chip.
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31. An accumulation-mode field-effect transistor (MOSFET) comprising:
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a semiconductor material; a gate positioned at least partially in a trench formed at a surface of said semiconductor material, said gate being separated from said semiconductor material by a gate insulating layer, said trench defining a transistor cell, said cell containing substantially only material of a first conductivity type; a first heavily-doped region of said first conductivity type located at a surface of said cell; a lightly-doped region of said first conductivity type adjacent said heavily-doped region; a second heavily-doped region of said first conductivity type located in said semiconductor material below said trench; wherein said gate is formed of polysilicon, said polysilicon being doped so as to form first and second diodes in said gate, said first and second diodes being connected in series between a portion of said gate within said trench and said first heavily-doped region. - View Dependent Claims (32, 33, 34)
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35. An accumulation-mode field-effect transistor (MOSFET) comprising:
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a semiconductor material; a gate positioned at least partially in a trench formed at a surface of said semiconductor material, said gate being separated from said semiconductor material by a gate insulating layer, said trench defining a transistor cell, said cell containing substantially only material of a first conductivity type; a first heavily-doped region of said first conductivity type located at a surface of said cell; a lightly-doped region of said first conductivity type adjacent said heavily-doped region; a second heavily-doped region of said first conductivity type located in said semiconductor material below said trench; wherein said gate is formed of polysilicon, said polysilicon being doped so as to form first and second diodes in said gate, said first and second diodes being connected in series between a portion of said gate within said trench and third heavily-doped region of said first conductivity type, said third heavily-doped region being coupled to said second heavily-doped region. - View Dependent Claims (36)
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Specification