| 摘要 |
PROBLEM TO BE SOLVED: To improve the performance of a device simply without causing the deterioration of the reliability of a gate oxide film or the lowering of yield with it, by setting the impurity concentration of a gate electrode on the side of a high voltage drive circuit lower than the impurity concentration of the gate electrode on the side of a low voltage drive circuit. SOLUTION: In doping the impurity to the gate electrodes 10 of a field effect transistor element (e.g. MOSFET2) that comprises each circuit of the high voltage drive circuit and the low voltage drive circuit, the impurity concentration of the gate electrode 10 on the side of the high voltage drive circuit is set lower than the impurity concentration of the gate electrode 10 on the side of the low voltage drive circuit. N<+> regions 14b and 16b, that are heavily doped with n type impurity, are formed on the deeply inner side of a substrate and n<-> regions 14a and 16a, that are doped comparatively lightly, are formed on the surface side of the substrate shallowly, elongated crosswise a little towards the center of the gate electrode 10. |
