| 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 germanium layer in the sidewall of the trench of a shallow trench isolation(STI) structure, and to prevent a characteristic of the device from being degraded by maintaining a uniform density of the boron ions in the p-well. 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 nitride layer and the semiconductor substrate in the trench region are removed to form the trench in the semiconductor substrate. The silicon germanium 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 nitirde layer. The nitride layer and the pad oxide layer are eliminated.
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