Verification of high-transmittance PSM with polarization at 193-nm high-NA system

High-transmittance phase shift mask (HTPSM) and high numerical aperture (NA) imaging with polarized illumination have been proposed as one of the solutions of the 65nm technology node and beyond. Both aerial image simulations and experimental exposure results confirm the advantages of the polarized illumination for high NA imaging. However, influence of transmission rate of the PSM status upon imaging performance had not yet been fully investigated. Consequently, the influence of different transmission rate PSM with polarized illumination upon imaging performance including depth of focus (DOF), exposure latitude (EL) and line edge roughness (LER) has been researched in this study. Simulation of normalized intensity log slope (NILS) vs. mask transmission rate for the through pitch line space patterns compared with experimental data are clearly showed. Masks of various transmission rates from 6%similar to 30% have been designed. The print images had been investigated with and without polarized illuminations of 193nm high NA tool. According to the experimental and simulation results, the high transmission rate 15% PSM certainly could enhance resolution for 50nm node and beyond.