| 摘要 |
PURPOSE:To prevent a malfunction due to an external noise by a method wherein the bottom of a drain of an MISFET is surrounded by a source which is biased at a definite potential and a substrate is insulated from the drain. CONSTITUTION:An n-type buried layer 9 is formed; it covers the bottom of a drain 4 and a channel formation part under a gate electrode; an n-type extraction region 6 which can reach the n-type buried layer 9 from a source 5 is formed; a source potential is supplied to the n-type buried layer 9; in addition, an n-type region 10 is formed also under a field oxide film 6; the grain 4 and a p-well 7 are separated completely from a p-substrate 1. When a noise electron is generated by an external noise inside the p-substrate 1, the noise electron is diffused inside the p-substrate 1. Because the diffused electron is captured in the source 5, the n-type extraction region 8, the n-type region 10 or the n-type buried layer 9, it does not reach the drain 4. By this setup, it is possible to prevent a malfunction of a circuit due to the external noise. |
