| 摘要 |
PURPOSE:To restrain a bird's beak from expanding by a method wherein, when the second oxide film is removed, the removal of the first oxide film beaneath the first nitride film by side etching process is protectively prevented by the second nitride film left on the sidewalls of three layered film and a recession in substrate. CONSTITUTION:An element separating region of three layered film comprising the first oxide film 3, the first nitride film 4 and the second oxide film 5 successively formed on a semiconductor substrate 1 is selectively opened. A recession 9 is formed on the substrate 1 by removing a part of substrate 1 exposed by the opening in the depth direction by etching process and then the inner surface of recession 9 is implanted with channel stopping ion. Next overall surface is covered with the second nitride film 17 which is anisotropically removed by etching process to leave the other nitride film 17' on the three layered film and the recession 9. Finally the second oxide film 5 and the third oxide film 10 are removed to form a new field oxide film 18 on the recession 9. Through these procedures, a bird's beak can be restrained from expanding. |
