Figure 5 shows typical calibration curves obtained for the anions of interest, and Table III lists the quantitative results for all five samples. These results are the average of three analyses. As the table indicates, anion concentrations in the HF solutions from different suppliers varied significantly. In particular, the HF from supplier B contained much higher concentrations of chloride and nitrate than the other samples. Typical calibration curves for the anions of interest quantified by the standard addition method.
Error bars are one standard deviation.
Anionic contaminants detected in samples of concentrated HF from three suppliers. The procedure should be useful in comparing products from various suppliers to ensure that semiconductor device reliability is not adversely affected by ionic impurities in process chemicals. Olin Microelectronic Materials provided funding to support this project. He specializes in trace analysis using microseparations, including multidimensional chromatography. He has authored or coauthored more than 10 research papers, a book chapter, and a review article.