| 摘要 |
A capacitor having low voltage dependency and high pn junction diode reverse breakdown voltage. A first n-well is formed in the surface of a p-type silicon substrate. A second n-well is superimposed and formed in the first n-well. A gate electrode is formed along the entire surface of the gate insulation film and part of the field insulation film. A p+ type diffusion layer having a high p-type impurity concentration is formed on the surface of the second n-well. The edge of the p+ diffusion layer is spaced from the boundary between the gate insulation film and the field insulation film at which an electric field concentrates.
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