Simulation-based approach for the accurate fabrication of blazed grating structures by FIB

Accurate direct fabrication of diffractive gratings is an important task in optical engineering. Several methods have been reported to realize optical diffractive gratings on a silicon substrate using focused ion beams. A method, however, is necessary to improve the overall shape and dimensional accuracy. In this paper a simulation-based technique is presented taking into account redeposition fluxes. First, the influence of the process parameters on the blazed grating structure is studied experimentally. Then the process parameters for a structure with a planar sidewall, a maximum depth of 200 nm, and an opening width of 350 nm are determined. The approach is finally verified by comparing the designed with the fabricated structure. The method may be readily extended to various micro/nano structures in optics.