| 摘要 |
PURPOSE: A method for manufacturing a field oxide layer of a semiconductor device is provided to test the alignment of a photoresist layer which is patterned during gate formation by enabling the bottom of the trench to have the unevenness. CONSTITUTION: The method for manufacturing the field oxide layer of the semiconductor device includes following steps. At the first step, a hard mask layer(25) exposing a predetermined portion on a semiconductor substrate is formed. At the second step, the trench having the unevenness is formed on the exposed bottom surface of the semiconductor substrate by using the hard mask layer as a mask. Then, a field oxide layer is formed in the trench. At last, the hard mask layer is removed to expose the semiconductor substrate. The second step further includes following steps. The semiconductor substrate is etched by using a mixture of Cl2 and HBr gas. Then, The semiconductor substrate is etched by using only the Cl2 gas.
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