Evaluation of resist sensitivity in extreme ultraviolet/soft x-ray region for next-generation lithography

At and below the 11 nm node, shortening the exposure wavelength to >10 nm (extreme ultraviolet (EUV)/soft x-ray region), especially at 6.6-6.8 nm, has been discussed as next-generation EUV lithography. In this study, dose/sensitivities of typical resists were obtained at several wavelengths down to 3.1 nm and were found to depend on the wavelength. However, it was confirmed that the absorbed dose, calculated from the dose/sensitivity and the respective linear absorption coefficient, was almost independent of the wavelength and constant for each resist. Thus, the resist sensitivity for next-generation lithography was predicted at wavelengths <10 nm.