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Suppression of molecular ions in SIMS spectra of metals and semiconductors
Author(s) -
McIntyre N. S.,
Fichter D.,
Metson J. B.,
Robinson W. H.,
Chauvin W. J.
Publication year - 1985
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740070203
Subject(s) - ion , silicon , semiconductor , mass spectrum , secondary ion mass spectrometry , kinetic energy , spectral line , chemistry , analytical chemistry (journal) , materials science , atomic physics , chemical physics , optoelectronics , physics , organic chemistry , chromatography , quantum mechanics , astronomy
Strong suppression of molecular ions in positive secondary ion mass spectra (SIMS) is achieved by electric isolation of a specimen (SI) with an electrically charged aperture situated immediately above its surface. This technique is also useful for controlling the surface charging on an insulator. The origin of this phenomenon has been explored using metals and semiconductors as models. The strong molecular suppression effect is found to result from the very high ion kinetic energies (>400 eV) emerging from the surface under SI conditions. The charged aperture is believed to stabilize surface charging by confining it within a small region. SI methods for reducing molecular ions in silicon and mild steel specimens reduce major molecular fragments by 3–4 orders of magnitude.