| 摘要 |
PROBLEM TO BE SOLVED: To prevent a silicon nitride film from being locally broken by a method wherein the surface of a first polycrystalline silicon film is thermally oxidized for the formation of a first silicon oxide film, the oxide film is removed, a silicon nitride film is formed, and a second silicon oxide and a second polycrystalline silicon are laminated thereon. SOLUTION: A first ground polysilicon film 2 is formed on a semiconductor substrate 1 through the intermediary of a silicon oxide film 11, and the surface of the ground polysilicon film is thermally oxidized for the formation of a first silicon oxide film 6. Then, the first silicon oxide film 6 is removed, when the pattern edge of the first ground polysilicon film 2 is rounded by trimming. A silicon nitride film 3 is formed on the first ground polysilicon film 2, and a second silicon oxide film 4 is formed thereon. Furthermore, a second polysilicon film 5 is formed on the second silicon oxide film 4. By this setup, the silicon nitride film 3 can be prevented from being locally broken, and a semiconductor memory device of this constitution can be ensured of a high capacity. |
