Evaluation of track performance for EUV lithography

One of the biggest issues in extreme ultraviolet (EUV) lithography technology is resist material development to improve optimum exposure dose and reduce line edge roughness (LER)/ line width roughness (LWR) and resolution. In order to attain these development targets, various kinds of challenges and innovative ideas are addressed by resist material researchers, for instance, introduction of polymer with lower molecular weight and increase of photo acid generator (PAG) addition amount have been presented. It is expected that these changes of resist materials will have big influence on not only general lithography performance but also track performance. In this paper, the application performance of EUV photoresist material, especially the spread behavior of photoresist just after resist dispense for a coating process, is evaluated using the model resist, dynamic contact angle measurement of resist material, dynamic drop base diameter measurement of resist droplet and so on. We have found that resist materials with small polymer size and high PAG loading have low spread property. From these results, we propose a new hypothesis that localized distribution of solid components that is formed just after resist dispense remains in a resist film after pre-baking and impacts resist performance.