Flame Emission Analysis for Sodium in Silicon Oxide Films and on Silicon Surfaces

Abstract

A flame emission spectrophotometric method has been developed for the determination of ultramicro amounts of sodium present in thin silicon oxide films and on cleaned silicon surfaces. Ultrapure 5% hydrofluoric acid is used as the solvent and the sodium measured directly in the solution by flame emission analysis. This method, which has a sodium detection limit of 0.2 ppb, is used in place of the more contamination‐prone neutron activation analysis to determine sodium distribution profiles in thin silicon oxide films as well as to measure the sodium contamination level of cleaned silicon surfaces. Sodium contamination on the surface of a single silicon wafer, having a surface area of approximately 16 cm2, can be detected down to .