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Nanometer Resolution XANES Imaging of Individual PC-RAM Devices

  • Jan H. Richter (a1) (a2), Milos Krbal (a1) (a2), Alexander V. Kolobov (a1) (a2) (a3), Paul Fons (a1) (a2) (a3), Xiaomin Wang (a1) (a2), Kirill V. Mitrofanov (a1), Robert E. Simpson (a1) (a2), Junji Tominaga (a1) (a2), Hitoshi Osawa (a3) and Motohiro Suzuki (a3)...


We introduce a technique to permit x-ray absorption spectroscopy studies focusing on individual phase-change (Ge2Sb2Te5) memory cells in fully integrated PC-RAM structures. Devices were investigated employing an x-ray nanobeam of only about 300 nm diameter, which could be fully contained within the spatial extent of the active area within a single device cell and enabled us to investigate individual devices without interference from non-switching material surrounding the area of interest. By monitoring the fluorescence signals of tungsten and germanium at a photon energy corresponding to the Ge K-edge absorption edge white line position, we were successful in producing 2D area maps of the active cell region, which clearly show the imbedded tungsten heater element and the switched region of the phase change material. Additionally, position dependent changes in the phase change material could be traced by taking an array of XANES spectra at the Ge K-edge on and in the vicinity of individual devices.



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