| 摘要 |
A method for forming a dual gate oxide layer, which can be suitably applied to the surface of a shallow trench isolation structure, comprising the steps of providing a substrate that has a device isolation structure already formed thereon such as a shallow trench isolation. Next, a thermal oxidation process is carried out to form an oxide layer over the substrate and the isolation structure. A silicon nitride layer is then deposited on top of the oxide layer. In the subsequent step, the silicon nitride layer is patterned to cover portions of the oxide layer that lies in an input/output area. The method of this invention produces a better quality gate oxide layer over the device isolation structure and the substrate surface. Therefore, device problems caused by the deposition of a poor quality gate oxide in a conventional method can be greatly reduced.
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