| 摘要 |
A process for forming a shallow trench isolation structure is provided. Firstly, a semiconductor substrate is provided. Then, a hard mask is formed over the semiconductor substrate, wherein the hard mask includes a pad oxide layer, a silicon nitride layer and an opening. Then, a trench is formed in the semiconductor substrate according to the opening Then, a pull-back process is performed to treat the silicon nitride layer at a sidewall of the opening, wherein the pull-back process is a wet etching process carried out in a phosphoric acid solution. After the pull-back process is performed, an insulating material is filled in the trench, thereby forming the shallow trench isolation structure.
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