Method for fabricating rim type photomask

A method for fabricating a rim type photomask, the method comprising:

• forming a phase shift layer and a light blocking layer on a substrate;
• forming a first mask pattern on the light blocking layer;
• forming a light blocking pattern from the light blocking layer using the first mask pattern;
• forming a phase shift pattern from the phase shift layer using the first mask pattern and the light blocking pattern;
• forming a groove in the substrate by etching an exposed portion of the substrate using the light blocking pattern and the phase shift pattern as an etch mask;
• forming a mask layer filling the groove formed in the substrate;
• forming a second mask pattern on the light blocking pattern, the groove being exposed by patterning the mask layer;
• shrinking the second mask pattern to expose a portion of the light blocking pattern by irradiating ultraviolet (UV) rays onto the second mask pattern, wherein a critical dimension (CD) size of the shrunken mask pattern is smaller than the CD size of the light blocking pattern;
• etching the exposed portion of the light blocking pattern using the shrunken mask pattern having the shrunken CD size as an etch mask;
• forming a height difference by etching the phase shift pattern by a predetermined thickness from a top surface of the phase shift pattern that is exposed by the etching of the light blocking pattern and the shrunken mask pattern;
• and
• forming a photomask including a rim region defined by the phase shift pattern having the height difference by removing the shrunken mask pattern.