A patterning method includes forming an etch-target layer on a substrate, forming mask patterns on the etch-target layer, and etching the etch-target layer using the mask patterns as an etch mask to form patterns spaced apart from each other. The etching process of the etch-target layer includes irradiating the etch-target layer with an ion beam, whose incident energy ranges from 600 eV to 10 keV. A recess region is formed in the etch-target layer between the mask patterns, and the ion beam is incident onto a bottom surface of the recess region at a first angle with respect to a top surface of the substrate and is incident onto an inner side surface of the recess region at a second angle with respect to the inner side surface of the recess region. The first angle ranges from 50° to 90° and the second angle ranges from 0° to 40°.