Line width roughness variation and printing failures caused by stochastic effect at extreme-ultraviolet exposure

Abstract

One of the challenges to achieving high volume manufacturing (HVM) using extreme ultraviolet (EUV) is to improve the line width roughness of photoresist (PR). In EUV having high photon energy, the intensity of the light source is insufficient, and a large number of photons cannot enter the resist, and thus a fine pattern with small roughness cannot be made. Roughness is not determined by only one factor but is manifested by various and complex photochemical reactions such as non-uniform photon distribution, dose, acid diffusion, and the reaction of PR components. In the EUV lithography process, the roughness varies even under the same conditions owing to stochastic effects and random printing failures may occur. Ultimately, to develop PR that will be applied to the mass production of EUV, it is necessary to study the factors affecting roughness formation among various phenomena occurring inside the resist. Through computational simulation, line edge roughness and line width roughness were calculated by reflecting stochastic effects in various aspects such as the initial distribution of materials in PR, photon density, and acid. To implement a finer pattern using EUV lithography, we must alleviate roughness by controlling the acid diffusivity and chemical reaction of the quencher. On the other hand, the ionization energy, which affects the interaction between the electron energy and the acid, changed the acid generation efficiency, but as a result, did not significantly affect the roughness. © 2021 SPIE.