| 摘要 |
PURPOSE: A method for forming an isolation layer in a semiconductor device is provided to be capable of removing hump due to back bias by rounding edge portions of a trench. CONSTITUTION: A buffer layer and a hard mask are sequentially formed on a semiconductor substrate(20). A trench is formed to expose the surface of the substrate(20) by selectively etching the hard mask and the buffer layer. A buried layer is formed on the resultant structure including the trench. The buried layer is partially removed by isotropic etching. By planarizing the remaining buried layer to expose the hard mask, edge facets are formed at edge portions of the hard mask. A hard mask is partially removed together with the edge facet. An isolation layer(28e) is formed by removing selectively the remaining hard mask, the buffer layer and portions of the buried layer.
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