1. A method of correcting patterns, comprising: attaining a correcting amount distribution map using a photo mask, the photo mask including a transparent substrate having first and second surfaces opposite to each other and a mask pattern on the first surface; attaining a plurality of shadowing maps based on the correction amount distribution map, each of the shadowing maps including a unit section having a different plane area; and forming a plurality of shadowing regions with shadowing elements in the transparent substrate of the photo mask using respective shadowing maps.