AVS 47th International Symposium
    Material Characterization Tuesday Sessions
       Session MC-TuA

Paper MC-TuA9
Measurement of Silicon Dioxide Film Thicknesses by XPS

Tuesday, October 3, 2000, 4:40 pm, Room 207

Session: Quantitative Surface Analysis
Presenter: C.J. Powell, National Institute of Standards and Technology
Authors: C.J. Powell, National Institute of Standards and Technology
A. Jablonski, Polish Academy of Sciences
Correspondent: Click to Email
It is now customary for the effects of elastic-electron scattering to be ignored in measurements of overlayer thicknesses by XPS. It is known, however, that elastic scattering can cause the effective attenuation length (EAL), needed for the thickness measurement,@footnote 1@ to be appreciably different from the corresponding inelastic mean free path.@footnote 2@ We have investigated the effects of elastic-electron scattering in measurements of the thicknesses of SiO@sub 2@ films on Si from XPS measurements with Al and Mg K@alpha@ x rays. Calculations have been made of substrate and oxide Si 2p photoelectron currents for different oxide thicknesses and emission angles using an algorithm based on the transport approximation.@footnote 3@ This algorithm accounts for the occurrence of elastic scattering along electron trajectories in the solid. It was found that the average EAL, determined from the substrate currents with and without an oxide overlayer of a certain thickness, varied weakly with oxide thickness and emission angle for a restricted range of emission angles. For emission angles greater than about 60°, corrections need to be made to this average EAL in order to determine the oxide thickness. These corrections will be described.@FootnoteText@ @footnote 1@A. Jablonski and C. J. Powell, Surf. Interface Anal. 20, 771 (1993). @footnote 2@A. Jablonski and C. J. Powell, J. Electron Spectrosc. 100, 137 (1999). @footnote 3@I. S. Tilinin, J. Zemek, and S. Hucek, Surf. Interface Anal. 25, 683 (1997).