Determination of particle-bound trace metals in high purity hydrogen chloride

Summary Two analytical procedures for the determination of particle-bound trace metals in high purity hydrogen chloride are described. Polycarbonate membrane filters with a pore diameter of 0.05 m were used for sampling. Membrane filtration with subsequent instrumental neutron activation analysis (using irradiation with a thermal neutron flux of 10¹³ n cm^–2 s^–1 and irradiation and measurement times of either 20 min) has made it possible to determine the elements Br, Mg, Mn, Na, Sb, Sn, Te, Ti and Zn. For a gas sample volume of 500 l the detection limits determined are in the range of 0.86 ng l^–1 for Zn to 0.30 pg l^–1 for Mn.The elements Cr, Cu, Fe, Mn and Ni were determined by membrane filtration with subsequent graphite tube furnace atomic absorption spectrometry. In this case the detection limits achieved are (for a gas sample volume of 500 l and 4 ml digestion solution) between 8.4 pg l^–1 for Fe and 2.1 pg l^–1 for Cu. The analytical procedures were applied for the characterisation of high purity hydrogen chloride, which is used in the manufacture of highly integrated semiconductor components, by trace analysis, both directly on the gas cylinder and at the 'point of use after passing through the supply system. A review of the status of element determination in high purity process gases is given.

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Bestimmung von partikelgebundenen Metallspuren in hochreinem Chlorwasserstoff