1. A method of measuring a depth of damage to a wafer, comprising: acquiring a first rocking curve for a prepared wafer using an X-ray diffraction apparatus; setting an X-ray incident angle range having a higher intensity than a reference level in the first rocking curve, calculating an interplanar distance for the set X-ray incident angle, calculating strain values of the wafer using the calculated interplanar distance, and extracting sampled strain values based on the calculated strain values; modeling a thickness according to a degree of damage to the wafer, based on an intensity of an X-ray diffraction beam corresponding to each of the sampled strain values; acquiring a second rocking curve, based on the set X-ray incident angle range, the calculated interplanar distance, the sampled strain values, and the modeled thickness; matching the second rocking curve with the first rocking curve by changing at least one of the X-ray incident angle range, the interplanar distance, the sampled strain values, and the modeled thickness; and calculating a depth of damage to the wafer based on the matched result.