US Patent 7745299 Semiconductor device and fabrication method thereof

In order to diversify a current control method of a semiconductor device, improve performance (including a current drive performance) of the semiconductor device, and reduce a size of the semiconductor device, a second gate may be formed inside a substrate that forms a channel upon applying a bias voltage thereto. In one aspect, the semiconductor device includes: a well region of a first conductivity; source and drain regions of a second conductivity in the well region; a first gate on an oxide layer above the well region, controlling a first channel region of a second conductivity between the source region and the drain region; and a second gate under the first channel region.