An exposure system includes an exposure apparatus and a phase shift mask. The exposure apparatus emits a multi-wavelength light including a plurality of wavelengths different from each other. The phase shift mask includes a transparent substrate and a light blocking layer. The transparent substrate includes a first surface, and a second surface opposite to the first surface. The multi-wavelength light is incident into the first surface. The transparent substrate further includes a recess which extends from the second surface toward the first surface. The light blocking layer includes a first opening which exposes the second surface of the transparent substrate, and a second opening which is spaced apart from the first opening and exposes the recess of the transparent substrate.