AVS 53rd International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoA

Paper AS-MoA8
Attenuation Lengths for Measurement of SiO@sub 2@ Film Thicknesses by XPS

Monday, November 13, 2006, 4:20 pm, Room 2005

Session: Developing Methods for Data Analysis
Presenter: C.J. Powell, National Institute of Standards and Technology
Authors: C.J. Powell, National Institute of Standards and Technology
W.S.M. Werner, Technical University of Vienna, Austria
W. Smekal, Technical University of Vienna, Austria
Correspondent: Click to Email
Effective attenuation lengths (EALs) are needed for measurement of film thicknesses by XPS, and have often been obtained from the NIST Electron Effective-Attenuation-Length Database.@footnote 1@ These EALs are derived from a model in which it is assumed that the substrate and the overlayer film have the same electron-scattering properties. We have used the new NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA)@footnote 2@ to compute EALs for thin films of SiO@sub 2@ on Si. With SESSA, the actual scattering properties for each material are utilized, and the resulting EALs are considered more reliable. EALs have been calculated for two emission angles and several film morphologies to simulate recent careful experiments:@footnote 3@ (a) an SiO@sub 2@ layer of variable thickness (1.4 nm to 7.6 nm) on Si; (b) an SiO@sub 2@ layer of variable thickness and three thin intermediate suboxides on Si; (c) a carbonaceous layer, an SiO@sub 2@ layer of variable thickness, and three intermediate suboxides on Si. The new EALs show a larger variation with SiO@sub 2@ thickness than found previously.@footnote 4@ The implications of these results for SiO@sub 2@ thickness metrology will be discussed. @FootnoteText@ @footnote 1@http://www.nist.gov/srd/nist82.htm.@footnote 2@http://www.nist.gov/srd/nist100.htm.@footnote 3@M. P. Seah and S. J. Spencer, Surf. Interface Anal. 37, 731 (2005).@footnote 4@C. J. Powell and A. Jablonski, J. Vac. Sci. Tech. A 19, 2604 (2001).