Method to mitigate defect printability for ID pattern

The present disclosure provides a method to mitigate defect printability for an ID pattern in accordance with some embodiments. The method includes loading a mask to a lithography system, wherein the mask includes a one-dimensional integrated circuit (IC) pattern; utilizing a pupil phase modulator in the lithography system to modulate phase of light diffracted from the mask; and performing a lithography exposing process to a target in the lithography system with the mask and the pupil phase modulator.