In this contribution we briefly summarize the current status of Imaging XPS (iXPS) and Scanning Auger Microscopy (SAM). Novel instrument concepts are presented, one in either field achieving ultimate resolution beyond todays limits.
In iXPS a great obstacle for higher resolution is the limited X-ray brilliance in the analysis area in combination with the small electron acceptance angle of current spectrometers. Today commercial laboratory instruments are limited to approx. 3 µm resolution at best [1, 3, 4].
We present first results acquired with a NanoESCA instrument recently installed at LETI (CEA-MINATEC) in Grenoble [5,6]. A new lens concept provides a huge progress for the acceptance angle of photo electrons. This is combined with a patented abberation compensated analyser allowing the acquisition of typically 640x512 image pixels in a single shot. This offers the unique possibility to achieve 650 nm image resolution routinely as well as small spot spectra from areas below 1µm diameter.
In the field of Scanning Auger Microscopy (SAM) the spatial resolution of any instrument depends on the performance of its electron source. Crucial parameters are the probe diameter, the electron energy, and the beam current density. As state of the art a spatial resolution on the order of 10 nm and slightly below has been demonstrated recently on the most advanced instruments, using beam energies [1,2,3] as high as 20 keV. However, the Auger cross section increases for lower beam energies and the scattering volume in the sample decreases. Thus operation at lower beam energies is desirable, but the probe diameter still shall not increase to an counteracting extent.
We present SAM measurements acquired with a new electron source employing a patented lens system optimised for low beam energies and high current density. This concept enables the highest so far reported SAM resolution of 5 nm (at 10kV beam energy). Even at beam energies as low as 5 keV more than 20 nA beam current can be focussed into 10nm spotsize.
[1] Ulvac-PHI, www.ulvac-phi.co.jp
[2] JEOL, www.jeol.com
[3] Thermo VG Scientific, www.thermo.com
[4] Kratos, www.Kratos.com
[5] O. Renault et al. Surf. Sci. 2007, to be published.
[6] M. Escher et al., J. Electron Spectrosc. Relat. Phenom. 144-147, Jun 2005, 1179-1182
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