Patent ID: 7892960

Claim:
A method for forming a gate oxide of a semiconductor device, comprising the steps of: defining a first region where a gate oxide having a first thickness will be formed, a second region where a gate oxide having a second thickness will be formed and a third region where a gate oxide having a third thickness will be formed on a semiconductor substrate; forming a first oxide film on the semiconductor substrate and forming a second oxide film on the first oxide film; blocking the first region and selectively removing portions of the second oxide film and the first oxide film, which are formed on the second region and the third region; forming a third oxide film on the semiconductor substrate; blocking the first region and the second region and selectively removing a portion of the third oxide film, which is formed on the third region; and forming a fourth oxide film on the semiconductor substrate and then forming a nitride film thereon, wherein a gate oxide-having a triple structure of the first oxide film/second oxide film/nitride film is formed in the first region, a gate oxide having a double structure of the third oxide film/nitride film is formed in the second region and a gate oxide having a double structure of the fourth oxide film/nitride film is formed in the third region.