| 摘要 |
PURPOSE:To make it possible to absorb a current at a position as deep as a well, by providing a groove deeper than source and drain regions in a guard band forming part, diffusing impurities from the groove part, and providing a high concentration impurity region. CONSTITUTION:A part of a thin oxide film 24 on the surface of a substrate 21 is etched away. With oxide films 23 and 24 as masks, anisotropic etching is performed, and a groove part 43 having a width of 0.8mum and a depth of 1.5mum is formed. boron is diffused from polycrystalline silicon 25, in which boron is doped, into the silicon substrate 21 through the side surface and the bottom surface of the groove part 43. A P<+> high concentration impurity region 26 is formed at a deep position of the substrate surrounding the groove part 43. Thereafter, contact holes are provided in source and rain regions 28, 29, 31 and 32, and Al wirings 34 are formed. Thus, a large current, which causes latch-up, is absorbed from the guard band and the high concentration substrate. The abnormal conduction of the current in the semiconductor device can be blocked. |
