| 摘要 |
PURPOSE:To improve the curvature between the diffusion profile and the junction and thus to obtain almost identical forward dielectric strength to the backward blocking voltage by forming the guard ring simultaneously with formation of the insulator region to the planar-type thyristor. CONSTITUTION:P-type guard ring 16 is formed by diffusion simultaneously when insulator region 12 is formed on N-type semiconductor substrate 11. Then P-type emitter region 13 is formed by diffusion on the back of substrate 11 enclosed by region 12, and at the same time P-type base region 14 shallower than ring 16 is formed by diffusion on the surface of substrate 11 enclosed by ring 16. In this case, both the spherical and cylindrical junctions are produced within ring 16 by region 14 as shown by the dotted lines. After this, N-type emitter region 15 is provided within region 14 to obtain a planar-type thyristor. In such way, the diffusion profile within ring 16 becomes approximate to the slope junction with increased curvature radius, thus the forward blocking dielectric strength being increased. |
