Patent ID: 8446565

Claim:
A method of optical proximity correction for a photolithographic process in manufacturing semiconductor devices, the method comprising: collecting data in an optical system, the data including a critical dimension of a test pattern projected on a wafer and a set of exposure parameters associated with the test pattern in a setting of the optical system; dividing the size of an illumination source into a number of segments; modulating an intensity of each of the segments; calculating an intensity value based on the size and modulated intensity of each of the segments; calculating an evaluation value based on the intensity value and the set of exposure parameters; calculating a difference value based on the evaluation value and the critical dimension; repeating the steps of dividing and modulating to obtain a predetermined number of difference values; identifying one of the difference values that has a minimum value; and generating an adjusted pattern based on the size and modulated intensity of each of the segments associated with the one difference value that has the minimum value, wherein modulating the intensity of each of the segments further includes assigning an intensity level I x to an x-th one of a number of “n” segments in accordance with a rule: I x =ax +1, where a =−1/(n +1), x being an integer from 0 to n−1.