MULTIELEMENT CHARACTERIZATION OF HIGH-PURITY TITANIUM FOR MICROELECTRONICS BY NEUTRON ACTIVATION ANALYSIS

摘要

A radiochemical neutron activation analysis technique for the determination of 26 elements including the alpha-emitting elements Th and U and Cu, Fe, K, Na, Ni, and Zn has been developed. The radiochemical separation was performed by anion exchange on a Dowex 1 x 8 column from HF and HF/NH4F medium, It leads to a selective removal of the matrix-produced radionuclides Sc-46, Sc-47, and Sc-48 and a nearly selective isolation of Np-239, and Pa-233, th, indicator radionuclides of U and Th, respectively. Counting the intensive but unspecific 511-keV gamma-ray of Cu-64 was enabled by a selective extraction of copper with dithizone from 15 M HF. For K, Na, Th, and U, a limit of detection of 30, 0.05, 0.03, and 0.07 ng/g, respectively, was achieved. For the other elements, the detection limits were between 0.002 ng/g for Ir and 45 ng/g for Zr. The elements As, Cr, and Mn were assayed only by instrumental neutron activation analysis. These techniques were applied to the analysis of two titanium sputter target materials of different purity grade. Results from seven elements are compared with those of isotope dilution and glow discharge mass spectrometry.