Sidewall smoothing of micro-pore optics by ion beam etching

Ion beam was employed to smooth the sidewall surfaces of square pores with high aspect ratio in micro-pore optics (MPO) fabricated using LIGA technique. A small plate tilt angle of 2° was chosen during the smoothing process considering the high aspect ratio of the pores. The evolution of the spatial relation between the incident ion beam and the target surface with sample rotating was investigated. The Rq roughness values decreased from 7.1 to 3.6 nm after 240-minute smoothing by ion beam (Eion = 400 eV, Fluxion = 0.2 mA/cm2) and the surface morphology evolution with smoothing time was studied. The smoothing occurred with a grazing angle even less than 2°, indicating that ion beam may be a promising technique to smooth sidewalls of micro-pores with high aspect ratio.