| 摘要 |
PURPOSE:To make the titled element low in withstand voltage and strong against surge by a method wherein P-N junction layers to generate breakdown are made of diffused layers, and further breakdown is generated in the epitaxial layer on the substrate. CONSTITUTION:An N type epitaxial layer 22 is grown on the P type semiconductor substrate 21, further a P type diffused layer 23 is formed by diffusion in the periphery of the layer 22 down to a depth of reaching the substrate 21. An N type diffused layer 24 is formed in the layer 22 in the neighborhood of its center, and an N type diffused layer 25 is formed in the periphery of the layer 22. Moreover, in the layer 24, a P type P-N junction diffused layer 26 is formed by diffusion more shallowly than the layer 24; then, a P-N junction diffused layer 27 is formed over three layers 25, 22, and 23 more shallowly than the layer 25. The specific resistance can be reduced by such a diffuse-formation of the P-N junction layers for generation of breakdown, and a low withstand voltage can be obtained. Since breakdown occurs in the layer 22, this element can be made strong against surge. |
