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    Secondary Ion Mass Spectrometry for Surface Analysis
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    Keywords:
    Auger electron spectroscopy
    Electron spectroscopy
    Secondary electrons
    The interaction of O2 with atomically clean Si surfaces has been studied by UHV secondary ion mass spectroscopy (SIMS). Thermally cleaned and annealed Si (111) surfaces, as well as ion-bombarded Si (111) surfaces, have been investigated. The silicon-oxygen interaction was found to take place in two steps. In step (i) a monoatomical oxide layer on the surface is formed with an initial sticking coefficient for O2 of about 1 and 0.05 for Si (111) and ion-bombarded Si (111), respectively. In step (ii) this monoatomical layer grows very slowly into greater depth.
    Sticking coefficient
    Citations (26)
    We have constructed an electron impact postionizing optics for sputtered neutrals which can be used on quadrupole mass filters for combined secondary neutral mass spectrometry (SNMS), positive and negative secondary ion mass spectrometry (SIMS), and residual gas analysis (RGA). In the SNMS mode, residual gas and secondary ion suppression exceeds 106, and the signal-to-background ratio is better than 104. Detection limits better than 30 ppm are shown using primary ion beam (3 keV Ar+) doses of 80 μAs per amu scan. The sensitivity in the SNMS mode exceeds that of SIMS only if the secondary ion fraction of the sputtered particle flux is in the order of 10−5, which is excessively low. As a first application, we have quantitatively determined secondary neutral and ion fluxes as well as oxygen concentrations on oxygen loaded Si(100) surfaces by purely mass spectroscopic experiments.
    Secondary electrons
    Secondary emission
    Residual gas analyzer
    Quadrupole mass analyzer
    Neutral particle
    Citations (63)
    A new approach to surface studies by time-of-flight secondary ion mass spectrometry is proposed. The time-of-flight technique is implemented in an unconventional way utilizing a continuous-probing beam. The ‘‘birth’’ moment of the secondary ion is fixed by the detection of secondary electrons emitted when a probing-beam particle strikes the surface. Multichannel mass identification of secondary ions is thus possible using a low-intensity continuous-probing beam, which permits one to study fragile and extremely thin (down to few monolayers) objects, sensitive to damage by intense probing beam and high doses. The technique has been applied to thin (30-Å) self-supporting carbon foil, semiconducting material, and the sensitive surface of a microchannel plate.
    Secondary electrons
    Time-of-Flight
    Microchannel plate detector
    Secondary emission
    Citations (11)