Flare compensation for EUVL

At Selete, correction for flare based on a flare point-spread function (PSFF) is investigated. We divide a layout into a grid and calculate pattern density for each grid square, obtaining a density array as an approximation to the layout aerial image. Then, the density array is convolved with the PSFF to create an array of flare values. Using this flare-value array, we resize the layout. In the above correction flow, size of a grid square of density array and a selection of an approximate function of the PSFF have a great influence on the accuracy of flare value computation. In this study, correction for flare was applied to the fabrication of several test masks using the real PSFF obtained from a full-field step-and-scan exposure tool called EUV1. We report on the optimization of size of grid square, on a suitable approximation model of PSFF, and on feedbacks from exposure experiments.