| 摘要 |
PURPOSE:To sufficiently enhance surface dielectric strength near an electric field concentration at the surfaced exposed portion of the front face of a depletion layer occurring at high voltage applying time by forming a positive bevel regarding both junctions by forming the shape of the side of a high specific resistance layer having P-N junctions at both sides of a high dielectric strength semiconductor element to have two V-shaped sections, and properly selecting a distance from the P-N junction of the deepest portion of the V-shaped section to prevent the electric field concentration at the surface exposed portion. CONSTITUTION:The side of a thyristor element 1 is formed to have two V-shaped sections 21, 22, and a large-diameter portion 23 is provided at the intermediate. Accordingly, the exposed portions of junctions J1, J2 to the sections 21, 22 become positive bevel in the vicinity. The distance d1 between the deepest portion of the section 21 and the junction J1 and the distance d2 between the deepest portion of the section 22 and the junction J2 are set to the size of approx. the width of a depletion layer. The angle phi formed between the sections 21 and 22 in a central large-diameter portion 23 of a high specific resistance layer 12 is selected in a range that a surface electric field becomes sufficiently small. When a forward voltage between an anode electrode 3 and a cathode electrode 5 is sequentially increased, the front face 31 of the depletion layer sequentially moves to 32, 33. In other words, the front faces 32, 33 of the depletion layer largely spread near the side of the element 1 in a high voltage region near a rated voltage to significantly improve the surface dielectric strength, of the titled device. |
