Semiconductor device and method of manufacturing the same
First Claim
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1. A vertical MOS device having a trench gate structure, the semiconductor device comprising:
- a semiconductor body having a trench, the trench having an inlet, a sidewall and a bottom;
a gate insulation film disposed to cover the sidewall and the bottom of the trench, the gate insulation film comprising a laminate structure of a first silicon oxide film, silicon nitride film and a second silicon oxide film successively laminated in this order from a trench side; and
a gate electrode of a polycrystalline silicon which is doped with boron, the gate electrode filling the trench with the gate insulation film interposed, wherein;
the semiconductor body has a first region of a first conductivity type, a second region of a second conductivity type, and a third region of the first conductivity type vertically aligned along the trench, and thereby a vertical MOS structure is formed by the gate electrode in the trench, the gate insulation film on the sidewall of the trench, and the first through third region;
the laminate structure of the gate insulation film is disposed to cover at least the second region in the trench;
the silicon nitride film in the laminate structure has a film thickness and film quality sufficient for suppressing boron from passing through the silicon nitride film; and
the first silicon oxide film at the trench side in the laminate structure has a film thickness that is greater than a film thickness of the second silicon oxide film at the gate electrode side.
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Abstract
In a semiconductor device having a trench-gate structure in which polysilicon doped with boron is embedded in a trench, insulating film formed on the inner wall of the trench comprises ONO film, and silicon nitride film constituting the ONO film is formed to such film thickness and film quality that boron can be suppressed from passing through the silicon nitride film. Silicon oxide film is formed so that a top oxide film is thin and a bottom oxide film is thick.
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Citations
12 Claims
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1. A vertical MOS device having a trench gate structure, the semiconductor device comprising:
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a semiconductor body having a trench, the trench having an inlet, a sidewall and a bottom; a gate insulation film disposed to cover the sidewall and the bottom of the trench, the gate insulation film comprising a laminate structure of a first silicon oxide film, silicon nitride film and a second silicon oxide film successively laminated in this order from a trench side; and a gate electrode of a polycrystalline silicon which is doped with boron, the gate electrode filling the trench with the gate insulation film interposed, wherein; the semiconductor body has a first region of a first conductivity type, a second region of a second conductivity type, and a third region of the first conductivity type vertically aligned along the trench, and thereby a vertical MOS structure is formed by the gate electrode in the trench, the gate insulation film on the sidewall of the trench, and the first through third region; the laminate structure of the gate insulation film is disposed to cover at least the second region in the trench; the silicon nitride film in the laminate structure has a film thickness and film quality sufficient for suppressing boron from passing through the silicon nitride film; and the first silicon oxide film at the trench side in the laminate structure has a film thickness that is greater than a film thickness of the second silicon oxide film at the gate electrode side. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A vertical MOS device having a trench gate structure, the semiconductor device comprising:
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a semiconductor body having a trench, the trench having an inlet, a sidewall and a bottom; a gate insulation film disposed to cover the sidewall and the bottom of the trench, the gate insulation film comprising a laminate structure of a first silicon oxide film, silicon nitride film of 10–
30 nm in thickness and a second silicon oxide film successively laminated in this order from a trench side; anda gate electrode of a polycrystalline silicon which is doped with boron, the gate electrode filling the trench with the gate insulation film interposed, wherein; the semiconductor body has a first region of a first conductivity type, a second region of a second conductivity type, and a third region of the first conductivity type vertically aligned along the trench, thereby forming a vertical MOS structure by the gate electrode in the trench, the gate insulation film on the sidewall of the trench, and the first through third region; the laminate structure of the gate insulation film is disposed to locally cover the sidewall of the trench; the first silicon oxide film at the trench side in the laminate structure has a film thickness that is greater than a film thickness of the second silicon oxide film at the gate electrode side; and the gate insulation film on the bottom of the trench is a first thick silicon oxide film which has a film thickness greater than a film thickness of the laminate structure, the first thick silicon oxide film covering a corner of the bottom of the trench. - View Dependent Claims (11, 12)
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Specification