Feasibility study on the characterization of thin layers by charged-particle activation analysis

The purpose of this feasibility study was to investigate the possibilities and limitations of Charged-Particle Activation Analysis (CPAA) as a thin la yer characterization method, i.e., the determination of the mass thickness or the composition of a thin layer. Therefore industrially important layers of sputtered Al, AlOx,, TiOx (all three from the packaging industry), YBa2 Cu3O6+delta, and Y2O3-stabilized ZrO2 (both superconducting industry) on di fferent substrates were analyzed, and thereby the accuracy, the detection l imits, and the precision of the method were studied, To test the accuracy, the same materials were also analyzed with neutron activation analysis (NAA ) and inductively coupled plasma mass spectrometry (ICPMS), The results of CPAA compared with the results of NAA and ICPMS showed no significant diffe rence at the 95% confidence level. The detection limits expressed as mass t hickness were about 10(-2) mu g cm(-2) or expressed as thickness 0.04 nm fo r a monatomic layer of Al. The experiments showed that the precision of the method depends only on the counting statistics. Generally we can conclude that CPAA is an absolute method for the characterization of "thin" layers, with respect to composition and mass thickness determinations.