A cratering analysis for quantitative depth profiling by ion beam sputtering

• Published in: Surface science 1975-05, Vol.50 (1), p.29-52
• Main Author: Huffman, D.W.
• Format: Article
• Language: English
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(75)90171-5

The depth profiling of composition by sputtering with a stationary ion beam of non-uniform intensity is treated analytically. Attention is devoted to the situation where the experimental signal originates simultaneously from all or most of the sloping, sputtered crater, as in ion scattering spectrometry (ISS) or secondary ion mass spectrometry (SIMS). As a result the signal itself does not relate directly to the composition at any specific depth in the specimen. Data processing formulas for various degrees of correction are presented, starting with a very simple result for the Gaussian intensity distribution. Simulated ISS outputs and processed data points are then illustrated for a number of selected composition profiles. An alternative use of the analysis to determine the radial intensity distribution in an ion beam is presented with experimental data supporting the Gaussian beam approximation as modified by the so-called clipping factor. Finally a practical stratagem is proposed for overcoming such extraneous problems as beam intensity transients, while determining the depth profiles of the elements in specimens of several components.