Exposure system of improved mask drooping

PURPOSE: An exposure device is provided to offer uniform patterning effects by preventing the sagging of a mask by using a mask chuck of a structure dragging the boundary of the mask. CONSTITUTION: An exposure device capable of solving a mask sagging problem includes a light source unit, a stage, a chuck for a circuit board, and a mask chuck (100). The light source unit outputs beams comprising a light source and an optical system. The stage supports the circuit board receiving a beam from the light source unit. The chuck for the circuit board fixes the stage on the circuit board. The mask chuck prevents a mask from being sagged by pulling the boundary of a mask (200). [Reference numerals] (AA) No mask sagging