| 摘要 |
PURPOSE:To increase withstanding voltage without lengthening a distance between an element isolation region and a diffusion layer constituting an active element by forming a high-concentration diffusion layer having a conduction type reverse to a diffusion layer, in which an element is isolated, around the diffusion layer, in which the element is isolated. CONSTITUTION:N<+> type buried regions 12 and P<+> type buried regions 13 are shaped to the surface of a P<-> type Si substrate 11. An N<-> type epitaxial layer 14 is formed onto the whole surface. Consequently, the regions 12 and 13 diffuse to the layer 14 side. N<+> diffusion layers 16 are shaped into the layer 14. P<+> type diffusion layers 18 as one parts of element isolation regions are formed. The regions 13 and the layers 18 are unified, thus shaping the element isolation regions. An impurity in the layers 16 also diffuses to the peripheries of the element isolation regions at that time. A P-type base region 19, an N<+> type collector region 21 and an N<+> type collector extracting region are formed. According to such a semiconductor device, the layers 16 are shaped around the layers 18 and regions 13 as the element isolation regions, thus increasing withstanding voltage among the element isolation regions and the base region.
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