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30 April 1981 Reflection Spectroscopy Analysis Of Surfaces And Thin Films
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Internal and external reflection spectra of surfaces and surface layers show detailed structure caused by impurities. Various coatings on semiconducting surfaces have been examined for absorbing impurities and the offending species have been identified, located, and quantified. The impurity species are identified by com-parison with known absorption signatures, and their location in the film structure decided by comparing measurements made with varying angle of incidence and polarization. A causal transformation has been devel-oped that allows the calculation of the complex refractive index from the reflection spectrum of a single unknown layer in a known multilayer stack. If the bulk absorption coefficients are assumed for the impurities, then the amount of the species can be determined, within the accuracy of the model assumed. Water and hydro-carbon impurities typically are found at the surface or at other interface regions in monolayer or greater amounts for the production quality films measured. Water impurity concentrations as high as 5-107 have been observed in ThF4 films deposited on ZnSe or Ag mirrors. These spectroscopic measurements are non-destructive and can be used to single out individual chemical species in situ. The techniques have been found to give accurate results for various multiphase systems without restrictions as to number of phases. These techniques emphasize use of continuous spectra as opposed to several point data, and make liberal use of adjustable parameters such as angle of incidence and polarization.
© (1981) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Wayne J. Anderson and Wilford N. Hansen "Reflection Spectroscopy Analysis Of Surfaces And Thin Films", Proc. SPIE 0276, Optical Characterization Techniques for Semiconductor Technology, (30 April 1981);

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