| 摘要 |
A method for forming a high voltage gate oxide having a high quality and reliability for use with nonvolatile memory devices is provided. Field oxide isolation regions are formed in the top surface of a semiconductor substrate so as to define a first active region, a second active region, and a third active region. A sacrificial oxide layer is formed on the top surface of the semiconductor layer and overlying the first through third active regions. The sacrificial oxide layer is removed from only the first active region. A tunnel oxide layer is formed over the first active region and over the sacrificial oxide layer overlying the second active region and the third active region. A floating gate structure is formed in the first active region. The tunnel oxide layer and the sacrificial oxide layer over the respective second active region and third active region are removed subsequent to forming the floating gate structure. A high voltage gate oxide layer is formed over the second active region and the third active region. The high voltage gate oxide layer is removed from only the third active region. A low voltage gate oxide layer is formed over the third active region. As a result, nitride contamination at the oxide-to-substrate interfaces in the second and third active regions has been eliminated.
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