Controlled dissolution of silicon dioxide layers for depth resolved multielement analysis by inductively coupled plasma-mass spectrometry

TitleControlled dissolution of silicon dioxide layers for depth resolved multielement analysis by inductively coupled plasma-mass spectrometry
Publication TypeJournal Article
Year of Publication2009
AuthorsLorge SE, Houk RS
Journal TitleSpectrochimica Acta Part B-Atomic Spectroscopy
Volume64
Pages1235-1239
Date Published11
ISBN Number0584-8547
Accession NumberISI:000272910300011
Keywordsclass analysis, elements, glass, icp mass spectrometry, icp-ms, metallic contamination analysis, ray-fluorescence spectrometry, sio2 analysis, surface analysis, THIN, vpd, wafers
Abstract

Dissolution procedures were developed to control the number of surface layers removed, in an attempt to achieve depth resolved analysis by inductively coupled plasma-mass spectrometry (ICP-MS). NIST 612 glass was chosen because it is a homogeneous material with many elements at interesting concentrations. similar to 50 ppm. Varying dissolution time and HF concentration resulted in the reproducible removal of SiO2 layers as thin as 70 angstrom deep. Dissolved trace metals were determined after dilution by inductively coupled plasma-mass spectrometry (ICP-MS) with a magnetic sector instrument. The amount removed was determined from the concentration of a major element, Ca. With the exception of Zn, trace metal concentrations agreed reasonably well with their certified values for removal depths of 500, 300 and 150 angstrom. Zinc concentration was significantly high in all dissolutions indicating either a contamination problem or that Zn is removed at a faster rate than Ca. For the dissolutions that removed 70 angstrom of SiO2, Cr, Mn, Co, Sr, Cd, Ce, Dy, Er, Yb and U recovery results agreed with their certified values (similar to 50 ppm); Ti, As, Mo, Ba. and Th could not be determined because net intensities were below 3 sigma of the blank; and measured concentrations for Cu, Pb and Zn were well above the certified values. (C) 2009 Elsevier B.V. All rights reserved.

URL<Go to ISI>://000272910300011
DOI10.1016/J.Sab.2009.09.007