Study on flare in ArF immersion lithography

With the immersion liquid and hyper NA being adopted, the impact of flare on lithography performances is crucial and tangle-some. To analyze and control the flare is a critical technology to achieve good lithography performances. When 65 nm features are printed in ArF immersion lithography, the variation of light intensity, image contrast, CD uniformity, pattern-placement error and process window result from different numerical apertures (NA) and flare is calculated using the commercial software Prolith 9.0. The results show that the hyper NA enhances the impact of flare on lithography performances. The impacts of Y polarized light (the polarized direction is consistent with the line feature) on process window with different flare and numeric aperture (NA) were analyzed. The results show that the process window can be extended by making use of the Y polarized light, and the impact of flare on process window also can be reduced by using Y polarized light.