A method for repairing a mask includes receiving a mask having first and second defective regions. A first treatment is performed to the mask. After performing the first treatment, a first repair process is performed on the mask. The first defective region is repaired to form a first repaired defective region. A second treatment is performed to the mask, including the first repaired defective region. After performing the second treatment, a second repair process is performed on the mask. The second defective region is repaired to form a second repaired defective region.