Focused ion beam lithography and its application to submicron devices

Applications of focused ion beam (FIB) technology to lithography in the sub-half-micron region will be discussed. First, the special characteristics of FIB sputtering are studied, and the fabrication of a GaAs FET by the use of a bilayer structure is mentioned. Next, resist patterning using light ions, Be and Si, is investigated. This process has the advantage of high throughout due to the high rate of energy deposition into the resist. The last application is the dry development of a gallium-implanted resist. This process will be effective for use in nanometer-range lithography because it is free from pattern swelling normally resulting from wet treatments. These three processes are applied to the fabrication of submicron devices, and the results demonstrate the practical feasibility of FIB lithography.