The method of patterning a photosensitive layer includes providing a substrate including a first layer formed thereon, treating the substrate including the first layer with cations, forming a first photosensitive layer over the first layer, patterning the first photosensitive layer to form a first pattern, treating the first pattern with cations, forming a second photosensitive layer over the treated first pattern, patterning the second photosensitive layer to form a second pattern, and processing the first layer using the first and second patterns as a mask.