Analysis method of metal contamination for the isopropyl alcohol (IPA)

Isopropyl alcohol (IPA) has been commonly used for drying wafers at a final step of cleaning process. As a result, the demand for higher purity IPA has been increasing, and the quality control of metallic impurities in IPA using the reliable analytical method is required. In this study, issues on the analysis of metallic impurities in IPA at ultra-trace level were investigated, and some accurate analysis methods were successfully developed. Furthermore, Fe (iron) impurities in IPA were studied and we indicated that Fe impurities in IPA were smaller than 15 nm and have a positive charge.