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.