MOSFET with improved performance through induced net charge region in thick bottom insulator
First Claim
1. A semiconductor power device, comprising:
- a semiconductor substrate having dopants of a first conductivity type;
an epitaxial semiconductor region formed on the substrate doped with dopants of the first conductivity type to a lower doping concentration than the substrate;
a trench formed in the epitaxial semiconductor region;
a body region formed in the epitaxial semiconductor region proximate the trench, wherein the body region is doped dopants of a second conductivity type that is opposite the first conductivity type;
a source region of the first conductivity type formed proximate the trench such that the body region is between the source region and the epitaxial region, wherein a doping concentration of the source region is greater than a doping concentration of the epitaxial semiconductor region;
a thick bottom insulator formed in a lower portion of the trench;
an electrically conductive gate electrode formed in the trench above the thick bottom insulator, wherein the gate electrode is electrically insulated from a bottom of the trench by the thick bottom insulator and electrically insulated from sidewalls of the trench by a gate insulator; and
a region of induced net charge of the first conductivity type in the thick bottom insulator proximate an interface between the thick bottom insulator and the epitaxial semiconductor region, wherein the doping concentration of the epitaxial semiconductor region is two to three times the doping concentration for an epitaxial semiconductor region in a conventional (unshielded) MOSFET device.
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Accused Products
Abstract
A semiconductor power device includes a thick bottom insulator formed in a lower portion of a trench in a semiconductor epitaxial region. An electrically conductive gate electrode is formed in the trench above the bottom insulator. The gate electrode is electrically insulated from the epitaxial region by the bottom insulator and a gate insulator. Charge is deliberately induced in the thick bottom insulator proximate an interface between the bottom insulator and the epitaxial semiconductor region. 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.
17 Citations
19 Claims
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1. A semiconductor power device, comprising:
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a semiconductor substrate having dopants of a first conductivity type; an epitaxial semiconductor region formed on the substrate doped with dopants of the first conductivity type to a lower doping concentration than the substrate; a trench formed in the epitaxial semiconductor region; a body region formed in the epitaxial semiconductor region proximate the trench, wherein the body region is doped dopants of a second conductivity type that is opposite the first conductivity type; a source region of the first conductivity type formed proximate the trench such that the body region is between the source region and the epitaxial region, wherein a doping concentration of the source region is greater than a doping concentration of the epitaxial semiconductor region; a thick bottom insulator formed in a lower portion of the trench; an electrically conductive gate electrode formed in the trench above the thick bottom insulator, wherein the gate electrode is electrically insulated from a bottom of the trench by the thick bottom insulator and electrically insulated from sidewalls of the trench by a gate insulator; and a region of induced net charge of the first conductivity type in the thick bottom insulator proximate an interface between the thick bottom insulator and the epitaxial semiconductor region, wherein the doping concentration of the epitaxial semiconductor region is two to three times the doping concentration for an epitaxial semiconductor region in a conventional (unshielded) MOSFET device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for manufacturing a semiconductor power device, comprising:
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forming an epitaxial semiconductor region on a substrate doped with dopants of a first conductivity type, doping the epitaxial semiconductor region with dopants of the first type to a lower doping concentration than the substrate; forming a trench in the epitaxial semiconductor region; forming a body region in the epitaxial semiconductor region proximate the trench, wherein the body region is doped dopants of a second conductivity type that is opposite the first conductivity type; forming a source region of the first conductivity type proximate the trench such that the body region is between the source region and the epitaxial region, wherein a doping concentration of the source region is greater than a doping concentration of the epitaxial semiconductor region; forming a thick bottom insulator in a lower portion of the trench; forming an electrically conductive gate electrode in the trench above the thick bottom insulator, wherein the gate electrode is electrically insulated from a bottom of the trench by the thick bottom insulator and electrically insulated from sidewalls of the trench by a gate insulator; and deliberately inducing a region of net charge of the first conductivity type in the thick bottom insulator proximate an interface between the thick bottom insulator and the epitaxial semiconductor region, wherein the doping concentration of the epitaxial semiconductor region two to three times the doping concentration for an epitaxial semiconductor region in a conventional (unshielded) MOSFET device. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification