| 摘要 |
PURPOSE: A method for forming a shallow trench isolation region of a semiconductor device is provided to improve a step coverage of the trench isolation region and thereby to prevent defects in a subsequent process. CONSTITUTION: In the method, a pad oxide layer(12) and a nitride layer(13) are sequentially formed on a semiconductor substrate(11). A photoresist pattern is then formed on the nitride layer(13), and the underlying nitride layer(13) and the pad oxide layer(12) are partly etched together with a portion of the substrate(11) thereby to form the first trench isolation region. After removing the photoresist pattern, another nitride layer is formed over an entire structure and anisotropically etched to form a nitride sidewall(15) on side faces of the first trench isolation region. Next, the substrate(11) is dry-etched while the nitride layer(13) and the nitride sidewall(15) are used as a mask. Therefore, the second trench isolation region(16) is formed in the substrate(11). After that, the nitride layer(13) and the nitride sidewall(15) are removed, and an insulating layer is deposited on an entire structure to complete the shallow trench isolation region.
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