Buried gate transistor

A semiconductor device having a buried gate transistor, the semiconductor device comprising:

• 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.

A semiconductor device having a buried gate transistor, the semiconductor device comprising:

• 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.