Method of aligning an exposure apparatus, method of exposing a photoresist film using the same and exposure apparatus for performing the method of exposing a photoresist film

A method of exposing a photoresist film, comprising:

• moving a reference mask array having reference masks to an observation area of a plurality of microscopes so that reference marks correspond to center points of a plurality of microscopes fixed to a base wherein the reference marks are formed on the reference masks;
• assigning an origin of a reference coordinate system to a first center point of the center points;
• assigning center point coordinates to a second center point according to the reference coordinate system;
• crossing beam position detection marks formed between the reference marks with exposure points of exposure heads to assign beam coordinates to the exposure points according to the reference coordinate system;
• moving a target substrate to an observation area of each microscope to assign substrate coordinates to an alignment mark of the target substrate according to the reference coordinate system;
• and
• turning the exposure points on and off in accordance with image data indicating a transfer pattern in order to expose a photoresist film formed on the target substrate by using the substrate coordinates and the beam coordinates.