Semiconductor device containing dielectrically isolated PN junction for enhanced breakdown characteristics
First Claim
1. A semiconductor device comprising a semiconductor substrate, the semiconductor substrate comprising:
- a body region of a first conductivity type, a top electrode being in electric contact with a top surface of the substrate and with the body region, a bottom electrode being in electrical contact with a bottom surface of the substrate; and
a plurality of field shield regions of a second conductivity type, each of the field shield regions being laterally bounded by dielectric sidewalls, the dielectric sidewalls of each field shield region separating the field shield region from the body region, each field shield region being bounded from below by a PN junction with the body region, each of the field shield regions being in electrical contact with a field shield electrode;
wherein the electrical contact between the field shield electrode and each of the field shield regions is ohmic.
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Accused Products
Abstract
A semiconductor device includes a field shield region that is doped opposite to the conductivity of the substrate and is bounded laterally by dielectric sidewall spacers and from below by a PN junction. For example, in a trench-gated MOSFET the field shield region may be located beneath the trench and may be electrically connected to the source region. When the MOSFET is reverse-biased, depletion regions extend from the dielectric sidewall spacers into the “drift” region, shielding the gate oxide from high electric fields and increasing the avalanche breakdown voltage of the device. This permits the drift region to be more heavily doped and reduces the on-resistance of the device. It also allows the use of a thin, 20 Å gate oxide for a power MOSFET that is to be switched with a 1V signal applied to its gate while being able to block over 30V applied across its drain and source electrodes, for example.
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Citations
5 Claims
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1. A semiconductor device comprising a semiconductor substrate, the semiconductor substrate comprising:
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a body region of a first conductivity type, a top electrode being in electric contact with a top surface of the substrate and with the body region, a bottom electrode being in electrical contact with a bottom surface of the substrate; and a plurality of field shield regions of a second conductivity type, each of the field shield regions being laterally bounded by dielectric sidewalls, the dielectric sidewalls of each field shield region separating the field shield region from the body region, each field shield region being bounded from below by a PN junction with the body region, each of the field shield regions being in electrical contact with a field shield electrode; wherein the electrical contact between the field shield electrode and each of the field shield regions is ohmic.
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2. A semiconductor device comprising a semiconductor substrate, the semiconductor substrate comprising:
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a body region of a first conductivity type, a top electrode being in electric contact with a top surface of the substrate and with the body region, a bottom electrode being in electrical contact with a bottom surface of the substrate; and a plurality of field shield regions of a second conductivity type, each of the field shield regions being laterally bounded by dielectric sidewalls, the dielectric sidewalls of each field shield region separating the field shield region from the body region, each field shield region being bounded from below by a PN junction with the body region, each of the field shield regions being in electrical contact with a field shield electrode; wherein the electrical contact between the top electrode and the top surface is ohmic.
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3. A semiconductor comprising a semiconductor substrate, the semiconductor substrate comprising:
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a body region of a first conductivity type, a top electrode being in electric contact with a top surface of the substrate and with the body region, a bottom electrode being in electrical contact with a bottom surface of the substrate; and a plurality of field shield regions of a second conductivity type, each of the field shield regions being laterally bounded by dielectric sidewalls, the dielectric sidewalls of each field shield region separating the field shield region from the body region, each field shield region being bounded from below by a PN junction with the body region, each of the field shield regions being in electrical contact with a field shield electrode; wherein the electrical contact between the bottom electrode and the bottom surface is ohmic.
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4. A semiconductor device comprising a semiconductor substrate, the semiconductor substrate comprising:
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a body region of a first conductivity type, a top electrode being in electric contact with a top surface of the substrate and with the body region, a bottom electrode being in electrical contact with a bottom surface of the substrate; and a plurality of field shield regions of a second conductivity type, each of the field shield regions being laterally bounded by dielectric sidewalls, the dielectric sidewalls of each field shield region separating the field shield region from the body region, each field shield region being bounded from below by a PN junction with the body region, each of the field shield regions being in electrical contact with a field shield electrode; further comprising a vertical JEET device, wherein the substrate is of the first conductivity type, the contact between the top electrode and the top surface is ohmic, the contact between the bottom electrode and the bottom surface is ohmic, and the field shield electrode comprises a gate electrode of the vertical JFET device.
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5. A semiconductor device comprising a semiconductor substrate, the semiconductor substrate comprising:
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a body region of a first conductivity type, a top electrode being in electric contact with a top surface of the substrate and with the body region, a bottom electrode being in electrical contact with a bottom surface of the substrate; and a plurality of field shield regions of a second conductivity type, each of the field shield regions being laterally bounded by dielectric sidewalls, the dielectric sidewalls of each field shield region separating the field shield region from the body region, each field shield region being bounded from below by a PN junction with the body region, each of the field shield regions being in electrical contact with a field shield electrode; further comprising a vertical bipolar transistor, wherein the substrate is of a second conductivity type, the contact between the top electrode and the top surface is ohmic, the contact between the bottom electrode and the bottom surface is ohmic, and the field shield electrode comprises a base electrode of the vertical bipolar transistor.
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Specification