| 摘要 |
PURPOSE: To enable evading surface destruction, by making the maximum invasion degree of protective zones larger than the penetration degree of an adjacent high doped zone. CONSTITUTION: Protective zones 6a, 6b have the maximum penetration degree at positions adjacent to a high doped zone 3, and the maximum penetration degree of the protective zones 6a, 6b is made larger than the penetration degree of the adjacent high doped zone 3. Doped density of the protective zones 6a, 6b is reduced almost linearly in the direction parallel to a main plane 2. The density is reduced stepwise in the parallel direction. In this case, at least two step-differences are formed. Since a PN junction is in a recessed state along an edge of the high doped zone 3, the maximum electric field strength is reduced in the dangerous region. Since the penetration degree of the protective zones 6a, 6b is large, a PN junction of a region which is restricted by little doping gradient shown in the direction perpendicular to the main plane 2 has large dielectric strength. Thereby a semiconductor element has dielectric strength restricted only by inner breakdown. |
