Line edge roughness of developed resist at low dose electron beam exposure

Energy deposited in the resist is made not only by incident electrons, but also by the many secondary electrons generated, so that the influence of the exposure is spatially smoothened by the SE diffusion volume. Popular chemically amplified resists generate acid within the resist by an electron exposure, the spatial diffusion of which causes the electron exposure to be broadened and spatially smoothened. Further, by using a strong developer, which dissolves the resist with less sensitive to the electron exposure dose variation, unexposed parts of the resist can be dissolved, and the resist structure may be spatially smoothened. The influence of these factors is analyzed by simulation of the resist pattern after development. Thus, we present Monte Carlo simulations of electron trajectories in the resist.