ARXPS provides a non‐destructive method for producing depth profiles from ultra‐thin films such as transistor gate dielectrics. The generation of depth profiles from ultra‐thin films using ARXPS is not a direct process but involves calculating the ARXPS response from trial depth profiles and comparing this with the experimental data. The trial profile is then adjusted to improve the fit. This process is continued until the optimum fit is achieved. The profiles to be presented in this paper have been generated by a combination of maximum entropy, a genetic algorithm and Powell optimization; these processes are explained. The purpose of this paper is to assess the quality of the profiles produced, specifically for silicon oxynitride layers. A model oxynitride layer on silicon structure has been constructed. From that model, simulated angle resolved XPS data have been generated. The simulated data were then used to generate the depth profile using the techniques described above. Using this method, it is possible to assess the depth resolution of the method without the presence of any uncertainties regarding the sample. The reproducibility of the method and the effect of user‐selected parameters can also be assessed.

Topics
Transistors, Entropy, Evolutionary computation, Dielectric materials, Oxynitride, Thin films, Depth profiling techniques
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© 2005 American Institute of Physics.
2005
American Institute of Physics