Trench-gated Schottky diode with integral clamping diode
First Claim
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1. A trench-gated Schottky barrier diode comprising:
- a semiconductor body having first and second trenches formed at a surface thereof, said trenches being separated by a mesa, said mesa being doped with atoms of a first conductivity type;
a metal layer in contact with at least a portion of a surface of said mesa, said metal layer being selected and said mesa being doped such that a rectifying Schottky interface is formed between said metal layer and said surface of said mesa;
a gate electrode disposed within said trenches, said trenches being lined with a dielectric material such that said gate electrode is electrically insulated from said mesa; and
a PN junction clamping diode formed in said semiconductor body, said clamping diode being fabricated in parallel with a current path through said mesa, wherein said PN junction is between a diffusion of a second conductivity type opposite to said first conductivity type and a region of the first conductivity type in said semiconductor body, said diffusion extending to a level deeper than said trenches.
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Abstract
A trench-gated Schottky diode of the kind described in U.S. Pat. No. 5,365,102 is provided with an integral clamping diode which protects the gate oxide from damage from high electric fields and hot carrier generation when the device is reverse-biased. The clamping diode is arranged in parallel with the normal current path through the Schottky diode and comprises a PN junction created by a diffusion of opposite conductivity to the semiconductor material of the Schottky diode. In a preferred embodiment, the clamping diode is selected to prevent significant impact ionization near the trenched gate during either steady state- or deep depletion-induced avalanche breakdown.
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Citations
66 Claims
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1. A trench-gated Schottky barrier diode comprising:
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a semiconductor body having first and second trenches formed at a surface thereof, said trenches being separated by a mesa, said mesa being doped with atoms of a first conductivity type; a metal layer in contact with at least a portion of a surface of said mesa, said metal layer being selected and said mesa being doped such that a rectifying Schottky interface is formed between said metal layer and said surface of said mesa; a gate electrode disposed within said trenches, said trenches being lined with a dielectric material such that said gate electrode is electrically insulated from said mesa; and a PN junction clamping diode formed in said semiconductor body, said clamping diode being fabricated in parallel with a current path through said mesa, wherein said PN junction is between a diffusion of a second conductivity type opposite to said first conductivity type and a region of the first conductivity type in said semiconductor body, said diffusion extending to a level deeper than said trenches. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 57)
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17. A trench-gated Schottky barrier diode comprising:
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a semiconductor body having first and second trenches formed at a surface thereof, said trenches being separated by a mesa, said mesa being doped with atoms of a first conductivity type; a metal layer in contact with at least a portion of a surface of said mesa, said metal layer being selected and said mesa being doped such that a rectifying Schottky interface is formed between said metal layer and said surface of said mesa; a gate electrode disposed within said trenches, said trenches being lined with a dielectric material such that said gate electrode is electrically insulated from said mesa; and a PN junction clamping diode formed in said semiconductor body, said clamping diode being fabricated in parallel with a current path through said mesa, wherein said PN junction is between a diffusion of a second conductivity type opposite to said first conductivity type and a region of the first conductivity type in said semiconductor body, said semiconductor body comprises an epitaxial layer overlying a substrate, and said trenches extend to a level deeper than said diffusion. - View Dependent Claims (18, 19, 20, 51, 52, 53, 54, 55, 56)
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21. A trench-gated Schottky barrier diode comprising:
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a semiconductor body having first and second trenches formed at a surface thereof, said trenches being separated by a mesa, said mesa being doped with atoms of a first conductivity type; a metal layer in contact with at least a portion of a surface of said mesa, said metal layer being selected and said mesa being doped such that a rectifying Schottky interface is formed between said metal layer and said surface of said mesa; a gate electrode disposed within said trenches, said trenches being lined with a dielectric material such that said gate electrode is electrically insulated from said mesa; and a PN junction clamping diode formed in said semiconductor body, said clamping diode being fabricated in parallel with a current path through said mesa, wherein said PN junction is between a diffusion of a second conductivity type opposite to said first conductivity type and a region of the first conductivity type in said semiconductor body, and said PN junction has a radius of junction curvature where r≦
2 μ
m. - View Dependent Claims (22, 23)
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58. A trench-gated Schottky barrier diode comprising:
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a semiconductor body having first and second trenches formed at a surface thereof, said trenches being separated by a mesa, said mesa being doped with atoms of a first conductivity type; a metal layer in contact with at least a portion of a surface of said mesa, said metal layer being selected and said mesa being doped such that a rectifying Schottky interface is formed between said metal layer and said surface of said mesa; a gate electrode disposed within said trenches, said trenches being lined with a dielectric material such that said gate electrode is electrically insulated from said mesa; and a PN junction clamping diode formed in said semiconductor body, said clamping diode being fabricated in parallel with a current path through said mesa, wherein said metal layer is formed of a first metal and said gate electrode is formed of a second metal different from said first metal.
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59. A trench-gated Schottky barrier diode comprising:
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a semiconductor body having first and second trenches formed at a surface thereof, said trenches being separated by a mesa, said mesa being doped with atoms of a first conductivity type; a metal layer in contact with at least a portion of a surface of said mesa, said metal layer being selected and said mesa being doped such that a rectifying Schottky interface is formed between said metal layer and said surface of said mesa; a gate electrode disposed within said trenches, said trenches being lined with a dielectric material such that said gate electrode is electrically insulated from said mesa; and a PN junction clamping diode formed in said semiconductor body, said clamping diode being fabricated in parallel with a current path through said mesa, wherein said gate electrode is formed of doped polysilicon.
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60. A trench-gated Schottky barrier diode comprising:
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a semiconductor body having first and second trenches formed at a surface thereof, said trenches being separated by a mesa, said mesa being doped with atoms of a first conductivity type; a metal layer in contact with at least a portion of a surface of said mesa, said metal layer being selected and said mesa being doped such that a rectifying Schottky interface is formed between said metal layer and said surface of said mesa; a gate electrode disposed within said trenches, said trenches being lined with a dielectric material such that said gate electrode is electrically insulated from said mesa; and a PN junction clamping diode formed in said semiconductor body, said clamping diode being fabricated in parallel with a current path through said mesa, said PN junction formed such that an avalanche breakdown is located away from said trenches. - View Dependent Claims (61, 62, 63, 64, 65, 66)
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Specification