Surface Characterization by Ion Microprobe Analyzer

Abstract

The ion microprobe mass analyzer (IMMA) is a comparatively recent tool which permits mass spectroscopic analysis on a microscale. IMMA analyzes secondary ions induced by bombarding the target with a high energy primary ion beam. The method is sensitive to all elements in the periodic table and in most cases this sensitivity is better than 1 ppm. The secondary ions which are analyzed are generated in the sample surface, hence the method is a surface characterization method. By successively sputtering material from the surface it is possible to monitor the thickness of surface layers with resolutions of a few tens of angstroms and at the same time to perform depth profile analyses for specific elements. The primary ion beam may be focused to a probe approximately 1 μm in diameter and thus particulate contamination of the sample surface may also be analyzed. Organic materials, too, may be identified in this method provided a suitable standard of the suspect material is available. There are, however, some limitations in the general application of the ion probe to unknown organic materials principally due to the high energy of the primary ion beam. Some examples of the application of the ion microanalyzer to surface characterization problems will be described.