Measurement of ion sputtering yields for in-depth profiling analysis

This article reports the results obtained in the second phase of the joint research for ion sputtering, conducted by the Surface Analysis Subcommittee of the Iron and Steel Analysis Committee, the Joint Research Society of ISIJ. Various effects on sputtering yields were studied in detail and the sputtering yields for Ni and Zn were determined by analyzing the results of an in-depth profiling of electrodeposited steels with Auger electron spectrometers. Ar+ ions were used as the bombarding ion species and a Faraday cup, which had a small hole for the ions to pass through in the center of an upper plate over a cup, was used to measure the electric current of incident ions. To calculate the ion current density, a correction for the effective transmittance efficiency of the hole was carried out in consideration of the cross-sectional shape of the hole. The sputtering yields determined in each laboratory by using this correction agree well with each other and show smaller scatter compared with those obtained in the previous phase. The angular dependence and energy dependence of the sputtering yields for Ni and Zn were also clarified. We, therefor, propose the standard procedure of ion sputtering for in-depth profiling analysis, including methods to measure the ion current, to calculate the ion current density, to optimize the sample position and to tune the lenses of the ion gun. (author)