Transistor with an offset gate structure
First Claim
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1. A semiconductor device comprising:
- a semiconductor substrate of a first conductivity type having a main surface;
a first and second diffused layers of a second conductivity type which are formed at the main surface of said substrate and which have a first impurity concentration;
a gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers;
a gate electrode formed on said gate insulating film;
first sidewalls which are formed on the sides of said gate insulating film and said gate electrode, extending upward from said substrate and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator;
second sidewalls which are formed on the sides of said first sidewalls, extending upward from said substrate and which are composed of said second insulator; and
a third and fourth diffused layers of the second conductivity type which are formed in said first and second diffused layers and which have a second impurity concentration higher than said first impurity concentration, with the interface with said first and second diffused layers being placed below said second sidewalls.
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Abstract
At the surface of a p-type silicon substrate, n-type source/drain diffused layers are formed. On the substrate between the source/drain diffused layers, a gate insulating film made of a silicon oxide film is formed so as to be isolated from the diffused layers. A gate electrode is formed on the gate insulating film. Sidewalls are formed on the sides of the gate insulating film and gate electrode, extending upward from the substrate. In this invention, the sidewalls are composed of material whose permittivity is higher than that of the gate insulating film, for example, of a silicon nitride film.
24 Citations
44 Claims
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1. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type which are formed at the main surface of said substrate and which have a first impurity concentration; a gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a gate electrode formed on said gate insulating film; first sidewalls which are formed on the sides of said gate insulating film and said gate electrode, extending upward from said substrate and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator; second sidewalls which are formed on the sides of said first sidewalls, extending upward from said substrate and which are composed of said second insulator; and a third and fourth diffused layers of the second conductivity type which are formed in said first and second diffused layers and which have a second impurity concentration higher than said first impurity concentration, with the interface with said first and second diffused layers being placed below said second sidewalls. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; first and second diffused layers of a second conductivity type formed at the main surface of said substrate; a gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a gate electrode formed on said gate insulating film; sidewalls which are formed on and along the sides of said gate insulating film and said gate electrode, extending upward from said substrate, and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator; offset regions within said substrate under said sidewalls, and indicating the same conductivity type as the substrate when no voltage difference exists between said gate electrode and said substrate and a conductivity opposite to that of said substrate when a voltage difference exists between the gate electrode and the substrate; and silicide layers formed in said first and second diffused layers. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type formed at the main surface of said substrate; a gate insulating film of a first film equivalent oxide thickness, which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from these first and second diffused layers; a gate electrode formed on said gate insulating film; an insulating film which is formed on the sides of said gate insulating film and said gate electrode, extending upward from said substrate, and which has a second film equivalent oxide thickness thinner than the first film equivalent oxide thickness of said gate insulating film; and sidewalls which are formed on said insulating film and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type formed at the main surface of said substrate; a gate insulating film of a first film thickness, which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from these first and second diffused layers; an insulating film which is composed of the first insulator the same as said gate insulating film and formed on the sides of said gate insulating film, extending upward from said substrate, and which has a second film thickness thinner than the first film thickness of said gate insulating film; a gate electrode formed on said gate insulating film; and sidewalls which are formed on the sides of said gate insulating film and said gate electrode above said insulating film, extending upward from said substrate, and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type formed at the main surface of said substrate; a gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a gate electrode formed on said gate insulating film so as to partly extend beyond the gate insulating film; and sidewalls which are formed on the sides of said gate electrode, extending upward from said substrate, so as to fill up a clearance between said gate electrode and substrate caused by said gate electrode extending beyond said gate insulating film and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator. - View Dependent Claims (28, 29, 30, 31, 32)
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33. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type formed at the main surface of said substrate; a first gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a floating gate electrode formed on said first gate insulating film; a second gate insulating film formed on said floating gate electrode; a control gate electrode formed said second gate insulating film; and sidewalls which are formed on and along the sides of said first gate insulating film, floating gate electrode, second gate insulating film, and control gate electrode in that order, extending upward from said substrate, and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator. - View Dependent Claims (34)
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35. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type which is formed at the main surface of said substrate and which have a first impurity concentration; a first gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a floating gate electrode formed on said first gate insulating film; a second gate insulating film formed on said floating gate electrode; a control gate electrode formed on said second gate insulating film; first sidewalls which are formed on and along the sides of said first gate insulating film, floating gate electrode, second gate insulating film, and control gate electrode in that order, extending upward from said substrate, and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator; second sidewalls which are composed of said second insulator and formed on the sides of said first sidewalls, extending upward from said substrate; and a third and fourth diffused layers of a second conductivity type which are formed in said first and second diffused layers and which have a second impurity concentration higher than said first impurity concentration, with the interface with said and second diffused layers being placed below said first second sidewalls. - View Dependent Claims (36)
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37. The semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type which is formed at the main surface of said substrate; a first gate insulating film of a first film equivalent oxide thickness which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a floating gate electrode formed on said first gate insulating film; a second gate insulating film formed on said floating gate electrode; a control gate electrode formed on said second gate insulating film; insulating films which are formed on and along the sides of said first gate insulating film, floating gate electrode, second gate insulating film, and control gate electrode in that order, extending upward from said substrate, and which have a second film equivalent oxide thickness thinner than the first film equivalent oxide thickness of said first gate insulating film; and sidewalls which are formed on the sides of said first insulating films and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator. - View Dependent Claims (38)
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39. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type which is formed at the main surface of said substrate; a first gate insulating film of a first film thickness which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from these first and second diffused layers; insulating films which are composed of the first insulator the same as said first gate insulating film and formed on the sides of said first gate insulating film, extending upward from said substrate, and which have a second film thickness thinner than the first film thickness of said first gate insulating film; a floating gate electrode formed on said first gate insulating film; a second gate insulating film formed on said floating gate electrode; a control gate electrode formed on said second gate insulating film; and sidewalls which are formed on and along the sides of said first gate insulating film, floating gate electrode, second gate insulating film, and control gate electrode in that order, extending upward from said substrate, and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator. - View Dependent Claims (40)
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41. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type formed at the main surface of said substrate; a first gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a floating gate electrode formed on said first gate insulating film so as to partly extend beyond the insulating film; a second gate insulating film formed on said floating gate electrode; a control gate electrode formed on said second gate insulating film; and sidewalls which are formed on and along the sides of said floating gate electrode, second gate insulating film, and control gate electrode in that order, extending upward from said substrate, so as to fill up a clearance between said gate electrode and substrate caused by said gate electrode extending beyond said gate insulating film and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator. - View Dependent Claims (42)
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43. A semiconductor device comprising:
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a semiconductor substrate of a first conductivity type having a main surface; a first and second diffused layers of a second conductivity type formed at the main surface of said substrate; a first gate insulating film which is composed of a first insulator with a first permittivity and formed on the substrate between said first and second diffused layers so as to be isolated from the first and second diffused layers; a first gate electrode formed on said first gate insulating film; first sidewalls which are formed on the sides of said first gate insulating film and first gate electrode, extending upward from said substrate, and which are composed of a second insulator with a second permittivity higher than the first permittivity of said first insulator; a third and fourth diffused layers of the second conductivity formed at the main surface of said substrate; a second gate insulating film formed on the substrate between said third and fourth diffused layers so as to overlap with these third and fourth diffused layers; a second gate electrode formed on said second gate insulating film; and second sidewalls formed on the sides of said second gate insulating film and second gate electrode, extending upward from said substrate. - View Dependent Claims (44)
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Specification