Understanding the onset of EUV resist chemical stochastics

The ability of chemically amplified resists to transfer an aerial image at increasingly smaller dimensions is critical to EUV lithography success at increasingly smaller process nodes [Bisschop and Hendrickx, Extreme Ultraviolet (EUV) Lithography X (SPIE) 10957 37 (2019)]. Stochastic inhomogeneities in resist exposure and patterning have been studied, which include photon shot noise and resist surface roughness. However, previous work has indicated that inhomogeneities and defectivity are present in multicomponent resists beyond those predicted by random statistics [Jablonski et al. (Santa Clara, CA) p. 302 (2004); Woodward et al. Advances in Resist Materials and Processing Technology XXIV (SPIE) 6519 416 (2007); Fedynyshyn et al. Advances in Resist Technology and Processing XXIII (SPIE) 6153 387 (2006); Fedynyshyn et al. J. Vac. Sci. Technol. B, 24, 3031 (2006); Kohyama et al. Advances in Patterning Materials and Processes XXXVI (SPIE) 10960 218 (2019)]. This is thought to be due to self-segregation of components in the multi-component chemically amplified resist. The results in this paper show that the most critical part of the resist chemical segregation occurs during the spin coating process after a significant amount of the solvent has evaporated, but while there is still enough solvent to enable molecular mobility within the resist.