Disclosed herein is a method for forming a
triple gate oxide of a
semiconductor device. The method for forming a
triple gate oxide of a
semiconductor device includes 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 through
wet oxidation on the semiconductor substrate and forming a second oxide film on the first oxide film, blocking the first region and selectively removing portions 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 through
thermal oxidation 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 through
thermal oxidation 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.