SURFACE-ANALYSIS OF RF PLASMA OXIDIZED IN AND PBINAU FILMS USING ESCA

The composition of the upper portion of oxide layers on the surface of In and PbInAu alloy films has been quantitatively determined by variable-angle x-ray photoemission spectroscopy (XPS or ESCA). The oxide layers were formed using a combination of thermal oxidation and rf oxidation. In addition to indium oxide, lead oxide was detected in all films. The concentration of the lead oxide was essentially independent of the composition of the underlying metal film, but was strongly related to the rf-oxidation conditions. This shows that backscattering of material sputtered from the Pb-coated rf electrode during rf oxidation is the primary factor in determining the concentration of the lead oxide within the 20-A XPS sampling depth. Electron microprobe measurements of the Pb content of similarly oxidized indium samples showed good agreement regarding the relative amounts of Pb in the surface oxide region but indicated a Pb level about twice that determined by XPS.