Method for illumination uniformity correction in the illumination system of lithography

A method for correcting the illumination uniformity error in the illumination optical system of lithography is proposed. By analyzing the optical characteristic of the uniformity correction system, a mathematical model of the correction system is established based on the principle of linear invariant system and convolution. This model has the characteristics of bidirectional calculation, that is, the intensity distribution on the correction plane can be calculated from the distribution on the mask plane, and the intensity distribution of the mask surface can also be calculated from the distribution of the compensation surface. Then a method of uniformity correction device design is proposed based on this model and it is used to design a uniformity correction device in an actual lithography illumination system. Measurement results of the transmittance distribution and correction effect of the designed uniformity correction device validates that the correcting method established previously is correct and effective.