| 摘要 |
PURPOSE: A method for fabricating an isolation layer of a semiconductor device is provided to remarkably reduce an abnormal operation by forming a thermal oxide of a low etch rate on the sidewall of a trench so that the erosion of the edge of the trench is minimized even after a subsequent HF treatment process. CONSTITUTION: A pad oxide layer and a nitride layer are formed on a semiconductor substrate(200). A part of the nitride layer and the pad oxide layer is etched to expose the semiconductor substrate. A polysilicon layer is formed on the resultant structure. A high temperature oxidation thermal process is performed to form an oxide region on and in the exposed semiconductor substrate. A part of the oxide region and the semiconductor substrate are removed by the exposed width of the semiconductor substrate to finish the trench so that an oxide layer(230c) of a bird's beak type is left on the sidewall of the trench. A high density plasma(HDP) oxide deposition layer(240) is formed on the resultant structure to completely fill the inside of the trench. The HDP oxide deposition layer is planarized to expose the nitride layer. The nitride layer is eliminated. A self-aligned contact etch process is performed.
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