Focused Ion Beam Fabrication: Process Development and Optimization Strategy for Optical Applications

This work presents an optimization of focused ion beam (FIB) milling process for the fabrication of optical elements. Focused ion beam is a nanofabrication tool involving ion–beam material interaction at atomic or molecular levels. The ion–solid interactions have been investigated for the fabrication of desired 3D geometries. Focused ion beam dwell time is an important parameter and determines the final geometry and accuracy of the fabrication. An algorithm has been developed to optimize the ion beam dwell time for the desired geometry fabrication maintaining high accuracy. Binary Fresnel zone plates (FZPs) have been fabricated using the optimized simulation results for demonstration. The algorithm can be used for fabrication of 3D elements and micro/nano-structures for various applications.