| 摘要 |
PURPOSE:To improve the electrical isolation performance, by a method wherein the ion injection for forming an inversion preventing layer is carried out by using a rsist pattern as a mask. CONSTITUTION:After a p-well region 22, a silicon oxide film 23, a silicon nitride film 24 and a resist pattern 24 are formed on a substrate 21, phosphorus ions are injected to form an ion-injected layer 26. Then, after the pattern 24 is removed, the film 25 is etched with a resist pattern 27 used as a mask. Subsequently, boron ions are injected with the pattern 27 used as a mask. Then, after the pattern 27 is removed, a thermal oxidation treatment is applied with nitride film patterns 251', 252' used as masks to form a field oxide film 30 provided with a p+ type inversion preventing layer 291 and an n+ type inversion preventing layer 292. |
