Abstract
In addition to raising the numerical aperture of the imaging lens or reducing the exposing wavelength to improve resolution in optical lithography, a third direction is pursued, namely restoration of the potential resolution capability that is lost due to incorrect practice. Unlike the former two methods, a gain in depth of focus can accompany improvement in resolution. In this paper, elimination of vibration between the mask and the wafer, resist contrast improvement, and multilayer resist systems are cited as possible means for improvement. Simulation study are given on the effects of vibration and resist contrast improvement to quantitatively assess the improvements. © 1986 SPIE.