High-numerical-aperture effects in photoresist

Two-beam and three-beam vector interference in thin photoresist films is used to illustrate the striking differences between s-polarized and p-polarized high-numerical-aperture illumination. Both simulations and experiments are performed for several cases, including undyed photoresist on silicon, dyed photoresist on silicon, and the addition of an antireflective layer between the photoresist and the silicon. A 0.85 numerical-aperture system is examined. The major differences between s- and p-polarized illumination include elliptical versus rectangular features and lower contrast for p-polarized images.