Method for fabricating the semiconductor device

Provided is a method for fabricating a semiconductor device. The method for fabricating a semiconductor device includes exposing an active region and a device isolation region by patterning an etch prevention layer which is formed on a substrate which includes the active region and the device isolation region; nitrifying the upper surface of the exposed device isolation region by performing a plasma nitridation process; forming a first recess in the exposed active region; and forming a stress generation layer in the first recess.