An estimation of line width roughness of photoresists due to photon shot noise for extreme ultraviolet lithography using the percolation model

We numerically investigate image formation in a photoresist for extreme ultraviolet (EUV) lithography. We develop a simulation model based on percolation theory, which is applicable to the exposure and development of a metal nanoparticle resist. We model the formation of the negative-tone image by condensation of the resist particles after the absorption of EUV photons. We validate the model by making a comparison between the calculated and experimental contrast curve of the resist and show that the calculation reproduces the critical behavior of the image formation. With the model, we investigate the line width roughness of the image, which is caused by the effect of stochastic distribution of EUV photons, (e.g., photon shot noise). We discuss the dependence of the roughness on the dose as well as on the properties of the resist material, such as the absorption length, at a wavelength of 13.5 nm. (c) 2019 The Japan Society of Applied Physics