| 摘要 |
PURPOSE: A method for fabricating an isolation layer of a semiconductor device is provided to prevent boron ions in a p-well from being diffused into a trench by forming a silicon nitirde layer in the sidewall of the trench of a shallow trench isolation(STI) structure. CONSTITUTION: After a pad oxide layer and a nitride layer are formed on a semiconductor substrate(11), a trench region is defined. The nitride layer, the pad oxide layer and the semiconductor substrate in the trench region are removed to form the trench inside the semiconductor substrate. The silicon nitride layer(16) is formed in the semiconductor substrate inside the sidewall of the trench. A thermal oxide layer(17) is formed on the sidewall of the trench. After a high density plasma(HDP) oxide layer(18) is formed on the resultant structure, a planarization process is performed to expose the nitride layer. The nitride layer and the pad oxide layer are eliminated.
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