Nanoscale Surface Modifications by Magnetic Field-Assisted Finishing

A magnetic field-assisted finishing (MAF) process has been developed to reduce the sidewall surface roughness of the 5–20 μm wide curvilinear pores of microelectromechanical systems micropore X-ray optics. Although the feasibility of this process has been demonstrated on these optics, a clear understanding of the MAF process material removal mechanisms has not been attained. To discover these mechanisms, the MAF process is applied to a flat workpiece, allowing for direct observation and tracking of changes to distinctive surface features before and after MAF. Atomic force microscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy are used to analyze the surface morphology and composition with respect to polishing time. These observations suggest that the MAF process removes surface material, improving surface roughness (to 0.1 nm Rq on silicon) without significantly changing the shape of existing surface features. Moreover, the MAF process appears to remove material by mechanical means.