Mask repairing apparatus and mask repairing method

A mask repairing method, comprising:

• producing a stereoscopic image of a mask, in which a plurality of openings are defined;
• comparing the stereoscopic image with a normal image of the mask to produce a defect image of the mask, the defect image of the mask comprising m multi-level defect images corresponding to m multiple layers of a deficient part;
• and
• irradiating a laser beam onto the deficient part of the mask to remove the deficient part, based on the defect image,
• wherein the laser beam is sequentially irradiated onto the m multiple layers of the deficient part while repeatedly moving in a first direction and a second direction crossing each other to sequentially remove the m multiple layers, where m is a natural number.