APPLICATION OF HIGH-ENERGY SYNCHROTRON-RADIATION XPS TO DETERMINE THETHICKNESS OF SIO2 THIN-FILMS ON SI(100)

The escape depth of photoelectrons depends on their kinetic energy. We apply this relationship to measure film thicknesses from X-ray photoe lectron spectroscopy (XPS) measurements with tunable-energy synchrotro n radiation (SR). For this purpose, a ''high-energy SR-XPS'' instrumen t has been constructed and used to characterize thermally oxidized thi n films on Si(100) single crystals. In order to observe photoelectrons emitted from deeper regions than with conventional XPS, Si 1s photoel ectrons with an energy up to 4000 eV were measured with X-ray energies up to 5800 eV. The oxide thickness was estimated from measurements of the relative Si intensities from the oxide and the substrate at vario us photon energies. Our results suggest that the SR-XPS system is usef ul for measuring the thickness of thin films.