| 摘要 |
PROBLEM TO BE SOLVED: To prevent sunken parts from forming in the top end of an STI and suppress reduction of active region area due to bird's beaks. SOLUTION: Before forming trenches into a Si substrate 1 through a patterned silicon nitride film 4 used as a mask, it is etched until the main surface of the substrate 1 is exposed, the exposed sidewalls of a silicon oxide film 2 and a polysilicon film 3 and the exposed surface of the substrate 1 are oxynitrated to form an oxynitrated Si film 6, trenches are formed, a silicon nitride film is formed on their inner walls, and the trenches are filled with an insulator. In the process of forming the silicon oxide film on the inner walls, bird's beaks are formed on the sidewalls of the silicon oxide film 2 and the polysilicon film 3, and the oxynitrated Si film 6 suppresses the excessive growth of the bird's beaks and prevents sunken parts of bird beaks from growing. |
