| 摘要 |
PURPOSE: A method for forming a trench in a semiconductor fabricating process is provided to easily control a threshold voltage characteristic of a cell transistor included in a semiconductor device and facilitate the control of an interval of refresh time by forming a trench with a uniform type and by making an isolation layer have a stable structure. CONSTITUTION: A pad nitride layer(12) is formed on a substrate(10), and photoresist(14) is used to form a trench(16). An exposure and development process is performed on the photoresist to open a trench formation region. The pad nitride layer and the substrate in the open region are sequentially etched to form the trench. A partial region of the photoresist adjacent to the entrance of the trench is eliminated, and the pad nitride layer exposed by the removal of the photoresist is etched. A soft etch process is performed to round a substrate region at the entrance of the trench exposed by the etching of the pad nitride layer.
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