The range of light ions in polymeric resists

Abstract

The technique of ion beam lithography coupled with calculations using a Monte Carlo computer program for ion penetration in solids have been used to obtain various range parameters of hydrogen, helium, lithium, beryllium, boron, and carbon ions in polymethyl methacrylate resist. In the experiment, the resist is bombarded with ions and then developed in a 1 : 1 solution of methyl isobutyl ketone and isopropyl alcohol with the developed depth monitored as a function of time. The saturated developed depth is approximated as the mean path length of the ion in the resist. The physical basis of this approximation is discussed. The projected ranges and straggles of the specified ions at energies of 5–300 keV obtained by fitting the experimental data to the total range using a Monte Carlo program are presented. These range data can be used as guidelines to determine the resist mask thickness for ion implantation and for choosing resist thickness in ion beam lithography.