| CPC G03F 7/70733 (2013.01) | 20 Claims | 

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               1. A photo mask stage unit performing alignment on a photo mask, the photo mask stage unit comprising: 
            an aligning member for aligning the photo mask so that the photo mask is positioned in a proper position; and 
                guide members for supporting edges of the photo mask and guiding the photo mask to the proper position, 
                wherein the aligning member pushes the photo mask in a diagonal direction and 
                wherein the guide members include, 
                a first guide member for supporting a first corner portion where a first side surface and a second side surface of the photo mask meet, and 
                a second guide member positioned diagonally from the first corner portion and supporting a second corner portion where a third side surface and a fourth side surface of the photo mask meet, the second guide member including a first reverse movement prevention surface for supporting a third bottom corner where a bottom surface and the third side surface of the photo mask meet, and inclined upward in an outward direction away from the photo mask, the first reverse movement prevention surface inclined upward in an outward direction extending to a top surface of the second guide member. 
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