| 摘要 |
PURPOSE:To improve the element isolation of an element isolation area and improve the stability of an element to be formed in the isolated area by ion- implanting impurities into a silicon substrate after the formation and patterning of films and diffusing the impurity. CONSTITUTION:A third silicon oxide film 9 is formed by thermal oxidation or CVD. Then, B<+> 10 as impurity is ion-implanted over the whole surface of a silicon substrate and an impurity diffused area 11 for improving element isolation is formed directly under an element isolation gate oxide film 5 and element isolation side wall oxide films 8. The impurity diffused area 11 provided for improving element isolation is formed shallow in the element isolation area and deep in the element forming area in the substrate. Thus, influence on elements to be formed by the subsequent processes, especially on transistors, is eliminated. |
