Abstract
An isotope dilution mass spectrometric (IDMS) method with the thermal ionization (TI) technique has been developed for the determination of trace impurities of Cr, Fe, Ni, Cu, Zn, Ag, Cd, Tl, Pb, Th, and U in high-purity HF (50% by weight) used in the semiconductor industry. The evaporation step of the HF solution was carried out in an apparatus which did not significantly contribute to contaminations of the heavy metals to be analysed. This apparatus allowed fast evaporation of the HF solution of up to 200 ml/h and therefore also a fast trace heavy metal/matrix separation was carried out. The evaporation step was also used in connection with inductively coupled plasma mass spectrometry (ICP-MS) when applying the isotope dilution technique and an external calibration for quantification, respectively. The detection limits for TI-IDMS were (in pg/g): Cr=30, Fe=400, Ni=70, Cu=20, Zn=1100, Ag=70, Cd=10, Tl=1, Pb=16, Th=3, and U=1. With ICP-MS in combination with the evaporation step, detection limits of less than 50 pg/g have been achieved for Cr, Ni, and Zn and of <5 pg/g for the other elements except Fe, which could not be determined in concentrations less than 100 ng/g. On the other hand, the detection limits were much higher when the HF matrix was not removed before measuring by ICP-MS. A comparison of the different ICP-MS methods (isotope dilution technique and external calibration for both HF evaporated samples and those with HF matrix) with the results of TI-IDMS has been carried out. An excellent agreement was achieved between the results of TI-IDMS and the two ICP-MS methods using the HF evaporation step, whereas the ICP-MS techniques without HF evaporation essentially deviated from these results. Fe was the only trace element of all investigated heavy metals which could only be analysed by TI-IDMS in high purity HF in a concentration of about 3 ng/g. Although ICP-MS with isotope dilution and external calibration resulted in comparable analytical data, the ICP-IDMS method has some practical advantages such as time-saving and more reliable results.
Similar content being viewed by others
References
Ohmi T, Imaoka T, Sugiyama I, Kezuka T (1992) J Electrochem Soc 139:3317
Grasserbauer M, Stingeder G (1990) Fresenius J Anal Chem 337:701
Rath HJ, Neunteufel R (1990) Proc Electrochem Soc 90:335
Ertl J (1989): In: Halbeiterfertigung — Neue Trends bei Produktionsstrukturen und Fertigungsgeräten (GME-Fachbericht), VDE, Berlin, p 15
Houk RS (1986) Anal Chem 58:97 A
Heumann KG, Schindlmeier W, Zeininger H, Schmidt M (1985) Fresenius Z Anal Chem 320:457
Heumann KG (1990) In: Günzler H, Borsdorf R, Fresenius W, Huber W, Kelker H, Lüderwald I, Tölg G, Wisser H (eds) Analytiker Taschenbuch, vol 9. Springer, Berlin Heidelberg New York, p 191
Heumann KG (1988) In: Adams F, Gijbels R, van Grieken R (eds) Inorganic mass spectrometry. Wiley, New York, p 301
Heumann KG (1986) Fresenius Z Anal Chem 325:661
Fassett J, Paulsen PJ (1989) Anal Chem 61:643 A
Beer B, Heumann KG (1992) Fresenius J Anal Chem 343:741
Kawanabe I, Murase G, Yonezawa T, Maeno M, Miki N, Ohmi T (1993) Proceedings of the 17th Symposium of ULSI Ultra Clean Technology, Tokyo, p 302
Gießmann U, Greb U (1994) Fresenius J Anal Chem (in press)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Horn, M., Heumann, K.G. Comparison of heavy metal analyses in hydrofluoric acid used in microelectronic industry by ICP-MS and thermal ionization isotope dilution mass spectrometry. Fresenius J Anal Chem 350, 286–292 (1994). https://doi.org/10.1007/BF00322484
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00322484