A method includes: receiving a design layout comprising a feature extending in a peripheral region and a central region of the design layout; determining compensation values associated with a pellicle assembly and the peripheral region according to an exposure distribution in an exposure field of a workpiece; and adjusting the design layout according to the compensation values. The modifying of the shape of the feature according to the compensation values includes: partitioning the peripheral region into compensation zones, wherein the feature includes first portions disposed within the respective compensation zones and a second portion disposed within the central region; and reducing line widths of the first portions of the feature according to the compensation values associated with the respective compensation zones while keep the second portion of the feature uncompensated.