| 摘要 |
PURPOSE: A method for forming an isolation layer of a semiconductor device is provided to eliminate stress concentrated on the upper end of a trench by stacking multiple thermal oxide layers on the side surface and bottom surface of the trench at different temperatures and by anisotropically etching the multiple thermal oxide layers. CONSTITUTION: A trench is formed in a semiconductor substrate(21). The multiple thermal oxide layers(27,28,29) are formed on the side surface and bottom surface of the trench. The multiple oxide layers are anisotropically etched to form round-type multiple thermal oxide layers in a portion corresponding to the upper end of the trench. An isolation oxide layer is formed on the multiple thermal oxide layers corresponding to the trench.
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