Effects of Low Energy Electrons on Pattern Formation in Chemically Amplified Resist

Abstract

Nanoscale resist topography such as line edge roughness (LER) or line width roughness (LWR) is the most serious concern in sub-100 nm fabrication. In chemically amplified resists for electron beam (EB) and extreme ultraviolet (EUV), acid generators mainly decompose through the reaction with low energy electrons (∼ 0 eV). It has been reported that counter anion distribution is significantly different from proton distribution. Counter anions are inhomogeneously distributed outside a relatively smooth edge of proton distribution. This is caused by the fact that acid generators can react with low energy electrons. To make clear the role of low energy electrons in the resist pattern formation, the distributions of protons and counter anions generated in chemically amplified EB resists were investigated at the exposure dose up to 20 ?C/cm2. The degradation in the slope of image contrast caused by low energy electrons contributes to LER formation in chemically amplified resists for EB lithography.