| 摘要 |
PROBLEM TO BE SOLVED: To extend a depletion layer of an impurity diffusion layer under a gate electrode while suppressing an increase in the resistance of the impurity diffusion layer. SOLUTION: There are provided a gate electrode 12 formed via a gate oxide film 17 on a P well layer 3 defined by a field oxide film 6 for device isolation, and an N type source region 18 and drain region 19 provided on a P well layer 3 located on opposite sides of the gate electrode 12. At least the drain region 19 is provided from a position where it overlaps the gate electrode 12 to the field oxide film 6, and impurity diffusion concentration is adjusted by multiple ion doping such that the impurity diffusion concentration is lowest below the gate electrode 12, and the impurity diffusion concentration is distributed denser as it goes away from the gate electrode 12. The resistance of the impurity diffusion layer is substantially the same as in a prior art, and the N type drain region 19 where a depletion layer below the gate electrode 12 is extended can be provided on the P well layer 3.
|
