Depth Profiling of Multilayer Thin Films Using Ion Beam Techniques

Abstract

Functional properties of thin film structures depend a lot on the thickness and chemical composition of the layer stack. There are many analytical techniques available for the identification and quantification of chemical species of thin film depositions on substrates, down to a few monolayers thickness. For the majority of these techniques, extending the analysis to several tens of nanometres or more requires some form of surface sputtering to access deeper layers. While this has been done successfully, the analysis tends to become quite complex when samples analysed consist of multilayer films of different chemical composition. Ion beam analysis (IBA) techniques using projectile ions of energies in the MeV range have a demonstrated advantage in the study of multilayer thin films in that the analysis is possible without necessarily rupturing the film, up to over 500 nm deep in some cases, and without the use of standards. This chapter looks at theoretical principles, and some unique applications of two of the most widespread IBA techniques: Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection Analysis (ERDA), as applied to multilayer thin film analyses.