| 摘要 |
PURPOSE:To prevent change in threshold voltage value and decrease in mobility, by forming gate electrodes at a protruding part on a substrate, and forming a source region and a drain region on both sides of the protruding part. CONSTITUTION:An N-type source region 3 and a drain region 4 are formed on both sides of a protruding part on a P-type Si substrate 2. The protruding part 1 is formed with a P-type region 5 and a P<+> region 6 for preventing a leaking current. Gate electrodes 8 composed of poly-silicon doped with phosphorus P are formed on both sides of the side walls of the protruding part 1 through oxide films 7. A threshold voltage value is determined by the decrease in potential due to an electric field in the substrate 2 in this constitution. When the gap between the regions 3 and 4 is made narrow, carriers run only in the substrate 2. Therefore, change in threshold value and decrease in mobility are avoided. Since operation is performed only in an intensely inverted region, there is no problem even if hot carriers are generated in a weakly inverted region.
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