| 摘要 |
PURPOSE: A trench isolation method for a semiconductor device is provided to prevent concentration of an electric field on corners of a trench. CONSTITUTION: In the method, the first oxide layer(202) and a nitride layer(204) are sequentially formed on a semiconductor substrate(200) and covered with a patterned mask. The nitride layer(204) is then selectively removed through the superjacent mask to form the first trench. After the mask is removed, the substrate(200) is etched in part to round lower corners of the first trench. Then, a polysilicon sidewall(208) is formed on a side of the first trench, and the substrate(200) is etched again through the sidewall(208) to form the second trench(s2). A surface of the second trench(s2) is then oxidized so that the second oxide layer(210) is formed thereon. Thereafter, a filling material layer is formed enough to fill the second trench(s2) and then removed together with the first oxide layer(202) and the nitride layer(204) until the substrate(200) is exposed. An isolation layer is therefore obtained from the filling material layer remaining in the second trench(s2).
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