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This paper deals with a method enabling the preparation of thick metallic microstructures on metal substrates. Such metallic microstructures can be used as a resolution samples to characterize various microanalysis techniques, such as X-ray fluorescence (XRF) or X-ray photoelectron spectroscopy (XPS). Moreover, the patterned samples could be used as anodes to characterize focusing properties of X-ray tubes for micro CT systems. Considering that the standard lift-off technique is designated for structures with the thickness of several hundred nanometers at most, we had to modify lift-off technique to be possible to use it for preparation of very thick metal layers (several microns) with spatial resolution of a few microns. The mask with the desired pattern for UV exposure was prepared by e-beam lithography. SU-8 photoresist was used for a lift-off because of its aspect ratio ability, process purity and high resistance to heating. We used a thin layer of PMMA under the SU-8 masking layer to guarantee the photoresist would lift-off correctly. Thick aluminum layer was deposited by thermal evaporation. The dependence of metal layer thickness as a function of required exposed line width was determined. The final lift-off process was carried out in acetone ultrasonic bath. Generally, this technology can be used for the evaporate deposition of various materials with several microns thick layer in micron resolution.
Keywords: Lift-off technique, SU-8 photoresist, e-beam lithography, thick layer evaporation.© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.