BACKSCATTERING ANALYSIS OF THIN-FILMS ON NON-FLAT SURFACES

In order to allow for the analysis of contaminant layers on powder surfaces, methods of adapting ion beam analysis techniques for use on non-flat surfaces have been developed. In this work, particular attention is given to situations where the dimensions of the surface structures are much larger than the thickness of the film, but much smaller than the ion beam spot size. It is assumed that the surface material is conformal and evenly distributed across the surface. Two methods are discussed; both are designed to analyze backscattered ion energy spectra through the use of available simulation programs. Two methods rely on a knowledge of the distribution of surface-normal to beam-direction angles present on the surface shape to be studied. Examples of this and other relevant distribution functions corresponding to several types of surface shape will be shown. The methods described here are used to study oxide layers grown thermally on small (almost-equal-to 130 mum) spherical titanium powder particles. We also show examples of how to empirically determine the distribution of surface tilt angles present on a surface of unknown shape when the nature of the surface film is known.