Buried gate transistor
First Claim
1. A semiconductor device having a buried gate transistor, the semiconductor device comprising:
- a semiconductor body that includes a first active region surrounded by a trench isolation region;
a recess in a surface of the first active region, the recess having a bottom surface and vertical sidewalls;
a dielectric layer continuously and conformal lining an entire length of the bottom surface and the vertical sidewalls of the recess;
an electrode material filling the recess, wherein an upper portion of the electrode material extends above an uppermost surface of the first active region;
source/drain regions disposed in the first active region, the source/drain regions physically contacting a majority but not all of a length of the dielectric layer lining the vertical sidewalls of the recess;
a continuous doped channel region between the source/drain regions, the continuous doped channel region having a higher doping concentration along the bottom surface and a lower doping concentration along the vertical sidewalls; and
localized halo regions disposed in the first active region directly under the vertical sidewalls but not in a central portion of the continuous doped channel region.
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Abstract
An embodiment of the invention provides a semiconductor fabrication method. The method comprises forming an isolation region between a first and a second region in a substrate, forming a recess in the substrate surface, and lining the recess with a uniform oxide. Embodiments further include doping a channel region under the bottom recess surface in the first and second regions and depositing a gate electrode material in the recess. Preferred embodiments include forming source/drain regions adjacent the channel region in the first and second regions, preferably after the step of depositing the gate electrode material. Another embodiment of the invention provides a semiconductor device comprising a recess in a surface of the first and second active regions and in the isolation region, and a dielectric layer having a uniform thickness lining the recess.
92 Citations
23 Claims
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1. A semiconductor device having a buried gate transistor, the semiconductor device comprising:
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a semiconductor body that includes a first active region surrounded by a trench isolation region; a recess in a surface of the first active region, the recess having a bottom surface and vertical sidewalls; a dielectric layer continuously and conformal lining an entire length of the bottom surface and the vertical sidewalls of the recess; an electrode material filling the recess, wherein an upper portion of the electrode material extends above an uppermost surface of the first active region; source/drain regions disposed in the first active region, the source/drain regions physically contacting a majority but not all of a length of the dielectric layer lining the vertical sidewalls of the recess; a continuous doped channel region between the source/drain regions, the continuous doped channel region having a higher doping concentration along the bottom surface and a lower doping concentration along the vertical sidewalls; and localized halo regions disposed in the first active region directly under the vertical sidewalls but not in a central portion of the continuous doped channel region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A semiconductor device having a buried gate transistor, the semiconductor device comprising:
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a first active region surrounded by a trench isolation region; a recess in a surface of the first active region, the recess having a bottom surface and vertical sidewalls; a dielectric layer lining the bottom surface and the vertical sidewalls; an electrode material filling the recess; heavily doped source/drain regions disposed in the first active region, the heavily doped source/drain regions physically contacting a portion of the vertical sidewalls of the recess and the electrode material disposed between the source region and the drain region; and a continuous doped channel region disposed between the heavily doped source/drain regions and contacting the heavily doped source/drain regions, the continuous doped channel region having a higher doping concentration along the bottom surface and a lower doping concentration along the vertical sidewalls, wherein the electrode material filling the recess, the heavily doped source/drain regions and the continuous doped channel region form part of the buried gate transistor. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A semiconductor device having a buried gate transistor, the semiconductor device comprising:
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a first active region surrounded by a trench isolation region; a recess in a surface of the first active region, the recess having a bottom surface and vertical sidewalls; a dielectric layer lining the bottom surface and the vertical sidewalls; an electrode material filling the recess; heavily doped source/drain regions disposed in the first active region, the heavily doped source/drain regions physically contacting the vertical sidewalls of the recess and the electrode material disposed between the source region and the drain region; a continuous doped channel region disposed between the heavily doped source/drain regions and contacting the heavily doped source/drain regions, the continuous doped channel region having a higher doping concentration along the bottom surface and a lower doping concentration along the vertical sidewalls; and localized halo regions disposed in the first active region directly under the vertical sidewalls but not in a central portion of the continuous doped channel region, wherein a first portion of the localized halo regions overlap with a portion of the heavily doped source/drain regions and a second portion of the localized halo regions is disposed within the continuous doped channel region. - View Dependent Claims (23)
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Specification