| 摘要 |
PURPOSE: A method for forming a trench is provided to be capable of rounding the top corner portion of the trench. CONSTITUTION: A silicon substrate(1) defined by an isolation region(I) is prepared. A pad oxide layer(3), a pad nitride layer(5) and an anti-reflective coating layer are sequentially formed on the resultant structure. The first trench with vertical side profile is formed using a photoresist pattern. A quantity of polymer with spacer shape is formed at sidewalls of the pattern and the second trench with a slope are simultaneously formed by over-etching of the pad nitride layer. The third trench with rounded top corner is then formed by etching the second trench using the polymer as a mask.
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