Progress on the magnetic field-assisted finishing of MEMS micropore x-ray optics

Microelectromechanical systems (MEMS) micropore X-ray optics were proposed as an ultralightweight, high- resolution, and low cost X-ray focusing optic alternative to the large, heavy and expensive optic systems in use today. The optic's monolithic design which includes high-aspect-ratio curvilinear micropores with minimal sidewall roughness is challenging to fabricate. When made by either deep reactive ion etching or X-ray LIGA, the micropore sidewalls (re ecting surfaces) exhibit unacceptably high surface roughness. A magnetic eld-assisted nishing (MAF) process was proposed to reduce the micropore sidewall roughness of MEMS micropore optics and improvements in roughness have been reported. At this point, the best surface roughness achieved is 3 nm Rq on nickel optics and 0.2 nm Rq on silicon optics. These improvements bring MEMS micropore optics closer to their realization as functional X-ray optics. This paper details the manufacturing and post-processing of MEMS micropore X-ray optics including results of recent polishing experiments with MAF.