Resist development to improve flare issue of EUV lithography

This report will introduce novel resist materials including specific photo acid generator (PAG) to improve flare issue from the resist standpoint. We have developed a method to control the acid diffusion length from the PAG. It previously reported that acid diffusion length can be altered by the PAG anion size. In this report, we focused on the effect of the Tg of a resist film. The thermal flow rate of a resist film can suggest the approximate resist Tg. Therefore, we measured the thermal flow rate of the resist. And we found out passivity of acid diffusion control by changing PAG species and volume. Moreover, newly designed PAG tested was confirmed to have uniform distribution in the resist film with no PAG clustering at the resist surface at compared to our conventional PAG. This new positive tone resist formulation shows good performance under flare condition. In addition, we focused on the pattern density variation as one of the key parameters for flare value. Low pattern density indicated less flare value. It is considered that negative tone resist to have advantage for isolated line type features. Novel positive and negative tone type resists were compared side-by-side and discussed for its advantages at varying pattern densities.