Efficient and flexible Focused Ion Beam micromachining of Solid Immersion Lenses in various bulk semiconductor materials - An adaptive calibration algorithm

Focused Ion Beam (FIB) micromachining of Solid Immersion Lenses (SILs) in substrate material offers optical analysis solutions for current and future technologies without the limitations of external SIL systems. This work presents an efficient single iteration calibration algorithm. This algorithm enables the implementation of FIB created SILs using a variety of substrate materials, process chemistries and most importantly different SIL shapes to match sample thicknesses. The successful application on silicon and silicon carbide is presented by creating a 50 μm wide refractive lens segment with a radius of curvature of 60 μm. Laser scanning microscope images of a silicon sample demonstrate the optical benefit with a measured resolution of 274 nm.