Optimization of elastomeric phase masks for near-field photolithography

Rigorous electromagnetic theory has been used to optimize elastomeric phase masks for generating sub-100-nm parallel lines by means of near-field phot olithography J. A. Rogers , Appl. Phys. Lett. 70, 2658 (1997). In the near- field region, the scattering effect is so strong that the scalar theory is no longer adequate: A bright line was found adjacent to the dark line previ ously predicted by the scalar theory, and the widths of both lines were fou nd to be insensitive to the refractive index of the photoresist. The simula tion results are in good agreement with experimental studies, which showed that the bright and dark lines could be used to generate trenches and lines in a positive-tone photoresist by controlling the exposure time. Our simul ations also indicate that parallel lines as small as 50 nm can be generated by adjusting the parameters of the phase mask. (C) 2001 American Institute of Physics.