Power semiconductor device having a thin gate insulating film with high-k dielectric materials and method for manufacturing the same
First Claim
1. A semiconductor device comprising:
- a semiconductor layer of a first conductivity type;
a first semiconductor layer of the first conductivity type provided on a first surface of the semiconductor layer of the first conductivity type;
a second semiconductor layer of a second conductivity type provided on the first semiconductor layer;
a trench provided from the second semiconductor layer to the first semiconductor layer;
a gate insulating film composed of an oxide film and a protective layer, the oxide film covering the second semiconductor layer exposed at a sidewall of the trench and including at least one of aluminum and yttrium, and the protective layer being formed on the oxide film;
a gate electrode made of n-type polysilicon buried in the trench in direct contact with the gate insulating film and opposed to the second semiconductor layer across the oxide film and the protective layer;
an interlayer insulating film provided on the gate electrode;
a third semiconductor layer of the first conductivity type selectively formed on a surface of the second semiconductor layer, and in contact with the gate insulating film at the sidewall of the trench;
a first electrode electrically connected to a second surface of the semiconductor layer on an opposite side of the first surface; and
a second electrode electrically connected to the third semiconductor layer, wherein the protective layer includes one of a silicon oxide film, a silicon nitride film, and a silicon oxynitride film.
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Accused Products
Abstract
In general, according to one embodiment, a power semiconductor device includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, a trench, a gate insulating film, and a gate electrode. The second semiconductor layer is provided on the first semiconductor layer. The trench is provided from the second semiconductor layer to the first semiconductor layer. The gate insulating film is composed of an oxide film and a protective layer formed on the oxide film. The protective layer is opposed to the second semiconductor layer across the oxide film in the trench. The oxide film covers the second semiconductor layer exposed at a sidewall of the trench and includes at least one of aluminum and yttrium. The gate electrode is made of n-type polysilicon buried in the trench in direct contact with the gate insulating film.
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Citations
18 Claims
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1. A semiconductor device comprising:
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a semiconductor layer of a first conductivity type; a first semiconductor layer of the first conductivity type provided on a first surface of the semiconductor layer of the first conductivity type; a second semiconductor layer of a second conductivity type provided on the first semiconductor layer; a trench provided from the second semiconductor layer to the first semiconductor layer; a gate insulating film composed of an oxide film and a protective layer, the oxide film covering the second semiconductor layer exposed at a sidewall of the trench and including at least one of aluminum and yttrium, and the protective layer being formed on the oxide film; a gate electrode made of n-type polysilicon buried in the trench in direct contact with the gate insulating film and opposed to the second semiconductor layer across the oxide film and the protective layer; an interlayer insulating film provided on the gate electrode; a third semiconductor layer of the first conductivity type selectively formed on a surface of the second semiconductor layer, and in contact with the gate insulating film at the sidewall of the trench; a first electrode electrically connected to a second surface of the semiconductor layer on an opposite side of the first surface; and a second electrode electrically connected to the third semiconductor layer, wherein the protective layer includes one of a silicon oxide film, a silicon nitride film, and a silicon oxynitride film. - View Dependent Claims (4, 5, 8)
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2. A semiconductor device comprising:
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a semiconductor layer of a first conductivity type; a first semiconductor layer of the first conductivity type provided on a first surface of the semiconductor layer of the first conductivity type; a second semiconductor layer of a second conductivity type provided on the first semiconductor layer; a trench provided from the second semiconductor layer to the first semiconductor layer; a gate insulating film composed of an oxide film and a protective layer, the oxide film covering the second semiconductor layer exposed at a sidewall of the trench and including at least one of aluminum and yttrium, and the protective layer being formed on the oxide film; a gate electrode made of n-type polysilicon buried in the trench in direct contact with the gate insulating film and opposed to the second semiconductor layer across the oxide film and the protective layer; an interlayer insulating film provided on the gate electrode; a third semiconductor layer of the first conductivity type selectively formed on a surface of the second semiconductor layer, and in contact with the gate insulating film at the sidewall of the trench; a first electrode electrically connected to a second surface of the semiconductor layer on opposite side of the first surface; and a second electrode electrically connected to the third semiconductor layer, wherein the protective layer is an oxygen atom layer covering a surface of the oxide film on the gate electrode side. - View Dependent Claims (6)
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3. A semiconductor device comprising:
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a semiconductor layer of a first conductivity type; a first semiconductor layer of the first conductivity type provided on a first surface of the semiconductor layer of the first conductivity type; a second semiconductor layer of a second conductivity type provided on the first semiconductor layer; a trench provided from the second semiconductor layer to the first semiconductor layer; a gate insulating film composed of an oxide film and a protective layer, the oxide film covering the second semiconductor layer exposed at a sidewall of the trench and including at least one of aluminum and yttrium, and the protective layer being formed on the oxide film; a gate electrode made of n-type polysilicon buried in the trench in direct contact with the gate insulating film and opposed to the second semiconductor layer across the oxide film and the protective layer; an interlayer insulating film provided on the gate electrode; a third semiconductor layer of the first conductivity type selectively formed on a surface of the second semiconductor layer, and in contact with the gate insulating film at the sidewall of the trench; a first electrode electrically connected to a second surface of the semiconductor layer on opposite side of the first surface; and a second electrode electrically connected to the third semiconductor layer, wherein the protective layer is an nitrogen atom layer covering a surface of the oxide film on the gate electrode side. - View Dependent Claims (7)
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9. A method for manufacturing a semiconductor device, comprising:
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forming, on a first surface of a semiconductor layer of a first conductivity type, a first semiconductor layer of the first conductivity type having a lower first conductivity type impurity concentration than the semiconductor layer of the first conductivity type; forming a second semiconductor layer of a second conductivity type on the first semiconductor layer; forming a trench penetrating through the second semiconductor layer to inside of the first semiconductor layer; forming a gate insulating film by forming an oxide film and then forming a protective layer, the oxide film covering the second semiconductor layer exposed at a sidewall of the trench and including at least one of aluminum and yttrium, and the protective layer being made of an oxygen atom layer or a nitrogen atom layer covering a surface of the oxide film; forming a gate electrode made of n-type polysilicon buried in the trench in direct contact with the gate insulating film and opposed to the second semiconductor layer across the oxide film and the protective layer; forming an interlayer insulating film on the gate electrode so as to insulate the gate electrode from outside of the trench; selectively forming a third semiconductor layer of the first conductivity type in a surface of the second semiconductor layer so as to be in contact with the gate insulating film at the sidewall of the trench; forming a first electrode so as to be electrically connected to a second surface of the semiconductor layer on opposite side of the first surface; and forming a second electrode so as to be electrically connected to the third semiconductor layer and the second semiconductor layer. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification