There are provided methods of performing a photolithography process for forming asymmetric semiconductor patterns and methods of forming a semiconductor device using the same. These methods provide a way of forming asymmetric semiconductor patterns on a photoresist layer through two exposure processes. To this end, a semiconductor substrate is prepared. A planarized insulating interlayer and a photoresist layer are sequentially formed on the overall surface of the semiconductor substrate. A first semiconductor pattern of a photolithography mask is transferred to the photoresist layer, thereby forming a photoresist pattern on the photoresist layer. A second semiconductor pattern of a second photolithography mask is continuously transferred to the photoresist layer, thereby forming a second photoresist pattern on the photoresist layer. An etching process is performed on the planarized insulating interlayer to expose the semiconductor substrate, using the first photoresist pattern and the second photoresist pattern as etch masks.