A method of manufacturing a semiconductor device that includes: a first exposing step using a photomask in a first area of a semiconductor substrate; and a second exposing step using the photomask in a second area adjacent to the first area of the semiconductor substrate. The photomask includes a first transmitting pattern having a ring shape that is missing a part, and a supplemental second transmitting pattern having a shape corresponding to the missing part of the first transmitting pattern, so that a closed loop pattern is exposed by the first exposing step and the second exposing step on the semiconductor substrate.