Ultra-trace element analysis on Si wafer surface by total reflection X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) is an effective method for analyzing the chemical bonding state of material surface. The detection limit of XPS, however, is inferior to other analyzing methods, such as SIMS and TXRF. The total reflection XPS (TRXPS) is a method for improving the detection sensitivity. In this study, we examined the validity of TRXPS for the analyzing the contamination on a Si wafer surface. In this experiment, the glancing angle of X-ray(Al-Kα) was 1.1°, which satisfied the total reflection condition. The samples used were Si wafers contaminated by Fe and Cu. The detection limit of TRXPS was found to be 9E + 10 atoms/cm2 for Fe and Cu, which was improved by 40 times in comparison with that of the normal-type XPS. Accordingly, it can be said that TRXPS is a very effective method for the analyzing the contamination on a Si wafer.