| 摘要 |
PURPOSE:To prevent the generation of latchup, by arranging, between a well and a semiconductor substrate, a high concentration layer whose conductivity type is identical with that of the semiconductor substrate, and whose impurity concentration is higher than that of the semiconductor substrate. CONSTITUTION:Between the region of a P-type semiconductor substrate 1 and an N-well 2, a high concentration P<+> layer 11 is formed, whose impulity concentration is higher than that of the P-type semiconductor substrate 1. A depletion layer between the N-well 2 and the P<+> layer 11 is narrower as compared with the case where the high concentration P<+> layer 11 does not exisit. Accordingly, a P-N junction capacity also becomes larger in the case where the P<+> layer 11 is formed. By the effect of its capacitive coupling, a sharp and large change of electric potential in the N-well 2 and the substrate 1 can be restrained, so that latchup is hard to generate. |
