RBS ( Rutherford Backscatter) technique for thin films vs EPMA approach

[JohnF]

(I am not posting this in STRATGem section on purpose, as it does not specifically relate to Stratagem)

I have been using EPMA and thin film programs (GMRFilm, STRATAGem and now BadgerFilm) for backing out thin film compositions and thicknesses.

Someone recently contacted me and mentioned that they use RBS for _very_ accurate thin film determinations and indicated that sometimes EPMA-generated thin film results (using thin film software) may not produce the “right results”.

Is there anyone out there is probe land who is well versed in both RBS and EPMA-thin film analysis to give some information on this topic.

In googling around for 30 minutes, I learned some, but the impression is that RBS is also “model” based and fits the observed spectra with theoretical models based upon presumed (possible) compositions; thus one question would be, how sensitive is it to differences in stoichiometries, e.g. if the client stated they were trying to generate a 1:1 stoichometry of a film on a substrate, but it actually was 1:1.5, would there be enough sensitivity in RBS to distinguish the two?

[Mike Matthews]

Hi John,

I’ve no direct experience but I’ve read that RBS can’t resolve near-neighbour elements very well, and is no good for thicknesses below about 20nm.

[Probeman]

(I am not posting this in STRATGem section on purpose, as it does not specifically relate to Stratagem)

I have been using EPMA and thin film programs (GMRFilm, STRATAGem and now BadgerFilm) for backing out thin film compositions and thicknesses.

Someone recently contacted me and mentioned that they use RBS for _very_ accurate thin film determinations and indicated that sometimes EPMA-generated thin film results (using thin film software) may not produce the “right results”.

Is there anyone out there is probe land who is well versed in both RBS and EPMA-thin film analysis to give some information on this topic.

In googling around for 30 minutes, I learned some, but the impression is that RBS is also “model” based and fits the observed spectra with theoretical models based upon presumed (possible) compositions; thus one question would be, how sensitive is it to differences in stoichiometries, e.g. if the client stated they were trying to generate a 1:1 stoichometry of a film on a substrate, but it actually was 1:1.5, would there be enough sensitivity in RBS to distinguish the two?

I too would *very* much like to see a comparison between these two techniques!