| 摘要 |
PURPOSE: To prevent optical latchup by placing a second diffusion layer and a 1-conductivity-type fourth diffusion layer which transversely forms junction to the second diffusion layer in a second element forming region for ensuring stable operation CONSTITUTION: A p-well 2 has element forming regions 100, 200 and 300 which are divided by a field oxide film 4 and a p+-type stopper layer 3 which is directly under the field oxide film 4. Into the element forming regions, p-type and n-type impurities are selectively doped. In the element forming region 200, a p+-type fourth diffusion layer 14 is formed on the left and an n+-type second diffusion layer 12 is formed on the right. In the left-side element forming region 100, a p+-type second diffusion layer 12 is formed. In the right-side element forming region 100, a p+-type first diffusion layer 11 is formed. An insulation film 5 grows to cover the diffusion layers, and an opening is made above each diffusion layer, then a fourth contact 24, a second contact 22, and a first contact 21 are provided, finally a metal wiring 6 which short-circuits these diffusion layers is provided. In the element forming region 200, the fourth diffusion layer 14 which functions as a base contact layer is in contact with the second diffusion layer 12 which functions as an emitter.
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