| 摘要 |
PURPOSE:To optimize a breakdown voltage by a method wherein an opposite conductivity type low concentration layer is stretched out around an opposite conductivity type high concentration layer formed in a one conductivity type layer and stretching length is controlled. CONSTITUTION:An opposite conductivity type low concentration layer 3 is stretched out around an opposite conductivity type high concentration layer 2 formed in a one conductivity type layer 1 to form a protective diode. The stretching length LGR of the low concentration layer 3 is controlled. The N-type low concentration layer 3 is formed simultaneously when the offset part of a high breakdown strength N-type offset gete MOS transistor is formed, Moreover, the N-type low concentration layer 3 relieves the curvature of a P-N junction and the rate of the relief is varied with the length LGR. With this constitution, the breakdown voltage can be optimized.
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