Depletion MOS transistor and enhancement MOS transistor
First Claim
1. A semiconductor memory device comprising:
- a memory cell array including a memory cell transistor with a charge layer formed on a semiconductor layer with a gate insulating film interposed therebetween; and
a peripheral circuit including at least a first transistor,wherein the first transistor includes;
a first gate electrode disposed on a surface of the semiconductor layer with a first gate insulating film interposed therebetween;
a first channel region of a first conductivity type formed in the surface of the semiconductor layer close to a region located immediately below the first gate electrode, the first channel region having a first impurity concentration;
a first source region of the first conductivity type and a first drain region of the first conductivity type each formed in the surface of the semiconductor layer and each having a second impurity concentration higher than the first impurity concentration;
a first overlapping region of the first conductivity type formed in the surface of the semiconductor layer immediately below the first gate electrode where the first channel region overlaps the first source region and the first drain region, the first overlapping region having a third impurity concentration higher than the second impurity concentration;
a first contact region of the first conductivity type formed in at least a part of a surface of each of the first source region and the first drain region and having a fourth impurity concentration higher than the second impurity concentration; and
a first impurity diffusion region of the first conductivity type formed in a partial region of at least one of the first source region and the first drain region and having a fifth impurity concentration higher than the second impurity concentration and lower than the fourth impurity concentration, andthe first impurity diffusion region is formed in contact with the first contact region and away from the first overlapping region and positioned at least in a region between the first contact region and the first overlapping region.
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Accused Products
Abstract
A semiconductor memory device includes a first transistor. The first transistor includes a gate electrode, a channel region, a source region, a source region, an overlapping region, a contact region, and an impurity diffusion region. The channel region has a first impurity concentration. The source and drain regions have a second impurity concentration. The overlapping region is formed in the semiconductor layer where the channel region overlaps the source region and the drain region, and has a third impurity concentration. The contact region has a fourth impurity concentration. The impurity diffusion region has a fifth impurity concentration higher than the second impurity concentration and lower than the fourth impurity concentration. The impurity diffusion region is in contact with the contact region and away from the overlapping region and positioned at least in a region between the contact region and the overlapping region.
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Citations
14 Claims
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1. A semiconductor memory device comprising:
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a memory cell array including a memory cell transistor with a charge layer formed on a semiconductor layer with a gate insulating film interposed therebetween; and a peripheral circuit including at least a first transistor, wherein the first transistor includes; a first gate electrode disposed on a surface of the semiconductor layer with a first gate insulating film interposed therebetween; a first channel region of a first conductivity type formed in the surface of the semiconductor layer close to a region located immediately below the first gate electrode, the first channel region having a first impurity concentration; a first source region of the first conductivity type and a first drain region of the first conductivity type each formed in the surface of the semiconductor layer and each having a second impurity concentration higher than the first impurity concentration; a first overlapping region of the first conductivity type formed in the surface of the semiconductor layer immediately below the first gate electrode where the first channel region overlaps the first source region and the first drain region, the first overlapping region having a third impurity concentration higher than the second impurity concentration; a first contact region of the first conductivity type formed in at least a part of a surface of each of the first source region and the first drain region and having a fourth impurity concentration higher than the second impurity concentration; and a first impurity diffusion region of the first conductivity type formed in a partial region of at least one of the first source region and the first drain region and having a fifth impurity concentration higher than the second impurity concentration and lower than the fourth impurity concentration, and the first impurity diffusion region is formed in contact with the first contact region and away from the first overlapping region and positioned at least in a region between the first contact region and the first overlapping region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A depletion MOS transistor comprising:
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a gate electrode disposed on a surface of a semiconductor layer with a gate insulating film interposed therebetween; a channel region of a first conductivity type formed in the surface of the semiconductor layer close to a region located immediately below the gate electrode, the channel region having a first impurity concentration; a source region of the first conductivity type and a drain region of the first conductivity type each formed in the surface of the semiconductor layer and each having a second impurity concentration higher than the first impurity concentration; an overlapping region of the first conductivity type formed in the surface of the semiconductor layer immediately below the gate electrode where the channel region overlaps the source region and the drain region, the overlapping region having a third impurity concentration higher than the second impurity concentration; a contact region of the first conductivity type formed in at least a part of a surface of each of the source region and the drain region and having a fourth impurity concentration higher than the second impurity concentration; and an impurity diffusion region of the first conductivity type formed in a partial region of at least one of the source region and the drain region and having a fifth impurity concentration higher than the second impurity concentration and lower than the fourth impurity concentration, wherein the impurity diffusion region is formed in contact with the contact region and away from the overlapping region and positioned at least in a region between the contact region and the overlapping region. - View Dependent Claims (12, 13, 14)
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Specification