| 摘要 |
PROBLEM TO BE SOLVED: To form an almost round silicon trench opening having no angular parts and provided low-temperature side-face oxidation. SOLUTION: After a photoresist pattern 4 is formed, a silicon nitride film 3, an oxide film 2, and a silicon substrate 1 are continuously etched in the same etching chamber. The silicon nitride film 3 and the oxide film 2 are subjected to open-etching and over-etching under the same etching condition, and the over-etching step is carried out under a condition with a high selective ratio to silicon. As indicated in Figure (b), the silicon nitride film and the oxide film after the over-etching step has a reverse tapered shape in etching or a notched shape 5, while the trench is being etched.
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