Lithography with silicon ions

Some applications of focussed ion beams are discussed with special emphasis on the lithography aspects. Experimental data on the ranges of H⁺, Be⁺ and Si⁺⁺ in polymethylmethacrylate (PMMA) are presented. The sensitivity of PMMA to Si⁺⁺ ions is measured to be 0.35 µC/cm². It is shown by replication through a transmission mask that Si⁺⁺ ions with low to moderate incident energies, such as found in focussed ion beam systems, can be used for submicrometer lithography in single and multi-layer resist systems.