Simulation of amine concentration dependence on line edge roughness after development in electron beam lithography

Abstract

Line edge roughness (LER) of chemically amplified (CA) resist has evolved as a major class of issues when the required fabrication accuracy of future nanolithography gets close to the limit of materials. Near the material limit, processes have a significant impact on the limit of resist performance. In order to provide an insight into the mechanism of LER formation and survey the performance limit of CA resists, the LERs after development in positive-tone CA resist for electron beam lithography were investigated in terms of their dependences on the amine (quencher of proton/acid) concentration and exposure dose. The latent images formed during the acid formation and diffusion processes were simulated by a Monte Carlo technique. The development process described by Mack’s dissolution model was incorporated into the simulation. The LERs (high frequency) after development are discussed from the aspects of image contrast, acid diffusion length, and topography of developed pattern.