Energy dependence of proximity parameters investigated by fitting before measurement tests

Some years ago a method for fast and accurate experimental evaluation of the proximity parameters alpha, beta, eta was suggested [S. V. Dubonos et nl., Microelectron. Eng. 21, 293 (1993)]. The method, called the fitting before measurement procedure, is used for regular measurements of beta and eta in a wide energy range for different bulk substrates (Si, SiO2, mica, ZrO2, Al2O3, InAs, GaAs) and of ct as function of resist thickness and energy. An empirical relation from the fitting procedure allows one to extrapolate the beta and eta values to other substrates and energies. It is demonstrated that a resist of micron thickness can remarkably reduce the resolution of e-beam lithography. It is important that the reducing could not be improved by accurate focusing of the beam but could be overcome only by using a higher accelerating voltage. A phenomenological relation helps to predict resolution as function of resist thickness and electron energy. (C) 1997 American Vacuum Society.