Auger electron spectrometry, described

In other articles in this section, a method of analysis is described called Secondary Ion Mass Spectrometry (SIMS), in which material is sputtered from a surface using an ion beam and the minor components that are ejected as positive or negative ions are analyzed by a mass spectrometer. Over the past few years, methods that post-ion-ize the major neutral components ejected from surfaces under ion-beam or laser bombardment have been introduced because of the improved quantitative aspects obtainable by analyzing the major ejected channel. These techniques include SALI, Sputter-Initiated Resonance Ionization Spectroscopy (SIRIS), and Sputtered Neutral Mass Spectrometry (SNMS) or electron-gas post-ionization. Post-ionization techniques for surface analysis have received widespread interest because of their increased sensitivity, compared to more traditional surface analysis techniques, such as X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES), and their more reliable quantitation, compared to SIMS. 

The HREELS, Auger electron spectroscopy (AES) and thermal desorption spectrometry (TDS) experiments were carried out in a UHV chamber described previously.6 Briefly, the chamber was equipped with a HREELS spectrometer for vibrational analysis, a single-pass cylindrical mirror analyzer for AES measurements and a quadrupole mass spectrometer for TDS measurements. The HREELS spectra were collected in the specular direction with an incident energy of 3.5 eV and with a spectroscopic resolution of 50-80 cm-1. The TDS data were obtained by simultaneously monitoring up to 16 masses, with a typical heating rate of about 1.5 K s-1. 

The spin is an inherent property of an electron. Since the photo- or Auger electrons are ejected in a certain direction in space, for an ensemble of these electrons a spin polarisation vector P can be defined which gives the excess of individual spin components measured in three orthogonal directions (see Section 9.2.1). In Fig. 1.5 the components of P are shown for a convenient decomposition into one longitudinal, Plong, and two transverse components, P,ranS and PtransX, respectively. The measurement of these components requires an electron detector which is sensitive to spin. An example of the spectrometry of photoelectrons with spin-analysis will be described in Section 5.4. 

FIB and FIB/SEM systems are routinely used to prepare TEM lamellae (both cross-section and plan views) and SEM specimens, which have been used for secondary ion mass spectrometry, electron backscat-ter diffraction, and Auger analysis. These systems offer numerous advantages relative to the other techniques described in the previous sections. The main advantage is that the specimens can be prepared to within 50 nm of a feature of interest (FOI). Other advantages are (1) the lamella can be prepared with near parallel sidewalls enabling quantitative chemical analysis to be performed over the lamella (2) the ion beam is perpendicular to the surface of the sample so that less preferential milling occurs than with ion beam thinning and (3) the sample preparation time can be as short as 2 h. 

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