A lithography system includes a radiation source configured to generate an extreme ultraviolet (EUV) light. The lithography system includes a mask that defines one or more features of an integrated circuit (IC). The lithography system includes an illuminator configured to direct the EUV light onto the mask. The mask diffracts the EUV light into a 0-th order ray and a plurality of higher order rays. The lithography system includes a wafer stage configured to secure a wafer that is to be patterned according to the one or more features defined by the mask. The lithography system includes a pupil phase modulator positioned in a pupil plane that is located between the mask and the wafer stage. The pupil phase modulator is configured to change a phase of the 0-th order ray.