| 摘要 |
PURPOSE:To improve current-voltage characteristics, eliminate instability of a threshold voltage VT and improve a dielectric strength between a drain and a substrate by a method wherein an opposite conductive type region contacts an opposite conductive type layer and is separated from a same conductive type region which has a higher impurity concentration than a semiconductor substrate. CONSTITUTION:A thick gate oxide film 3 is formed on a P-type silicon substrate 1 by a LOCOS method. An N-type low concentration layer 8 is formed directly under the thick gate oxide film 3 by an ion implantation method so as to contact an N-type high concentration drain diffused layer 5. A P-type, the same conductive type as the silicon substrate 1, high concentration channel stopper layer 7 is formed under a source side field oxide film and not formed under a drain side field oxide film 2. As the low concentration layers of the gate and the drain overlap each other, a region in which there is no inversion does not exist so that current-voltage characteristics and instability of a threshold voltage of a MOSFET can be improved. As a channel stopper is not provided under the drain side field region, deterioration of a dielectric strength on the side of the channel stopper of the drain is eliminated. |
