Articles you may be interested inTowards three-dimensional and multilayer rod-split-ring metamaterial structures by means of deep x-ray lithography Appl. Phys. Lett. 90, 254106 (2007); 10.1063/1.2749865 Fabrication of two-and three-dimensional photonic crystals of titania with submicrometer resolution by deep xray lithography J. Vac. Sci. Technol. B 23, 934 (2005); 10.1116/1.1924421Fabrication of three-dimensional photonic structures with submicrometer resolution by x-ray lithography

Complex ceramic miniaturized structures that have much smaller dimensions and better precision than that which has been reported previously were prepared by a combination of X‐ray synchrotron lithography, casting, and pyrolysis processes. Poly(methyl methacrylate) and poly(tetrafluorethylene) miniaturized structures were prepared with high precision via a combination of X‐ray synchrotron lithography, electroplating, and molding (the German Lithographie, Galvanoformung, and Abformung (LIGA) process). Casting of a solution of a preceramic polymer, poly(vinylsilazane), in these miniaturized structures was performed for the first time, similar to the slurry‐casting technique of macroscopic bodies. Subsequent pyrolysis led to nearly perfect, complementary bodies of the original structures because of the high smoothness of the pyrolyzed ceramics. This was demonstrated by the complex spool and meander‐like miniaturized structures with internal dimensions <2 μm and an aspect ratio as high as 5. To evaluate optimal process parameters for the preparation of these complex ceramic miniaturized structures, the pyrolysis process of poly(vinylsilazane) was investigated using Fourier transform infrared spectrometry, X‐ray diffractometry, atomic force microscopy, and scanning electron microscopy. The first step of pyrolysis involved dehydrocoupling of –CH and –NH groups and nucleophilic substitution of the Si–CxHy groups, which led to the elimination of the CxHy substituents and the formation of an amorphous silicon carbonitride (Si:C:N) at 800°C. The residual hydrogen content, which was chemically bonded as Si‐H, decreased as temperatures decreased from 800° to 1400°C. Heating to 1500°C converted the amorphous structure to a semicrystalline phase‐separated ceramic composed of α‐Si3N4 crystals embedded in a carbon‐silicon amorphous matrix. The amorphous phase could be partially etched with a KOH solution. Because of the absence of grains, the amorphous material revealed a much smoother surface than that of the crystalline material or that possible by conventional slurry processes.