| 摘要 |
PURPOSE: A forming method of isolation region of semiconductor device is provided to prevent roughness of sidewalls in a deep trench isolation region. CONSTITUTION: A high-temperature low-pressure oxide layer(12) and a WSix layer are formed on a semiconductor substrate(11). A photoresist pattern is built with exposing some part of the WSix layer. By etching the exposed WSix layer, the high-temperature low-pressure oxide layer(12) is disclosed, and the photoresist pattern is removed. Using the remaining WSix layer as a hard mask, the exposed high-temperature low-pressure oxide layer(12) is etched to expose the semiconductor substrate(11). A deep trench(14) is made by etching the semiconductor substrate continually. The depth of trench(14) is more than 3 micrometer.
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