Measurement of vanadium impurity in oxygen-implanted silicon by isotope dilution and resonance ionization mass spectrometry

Abstract

The combined analytical capabilities of Isotope dilution, laser-induced resonance Ionization spectroscopy, and mass spectrometry, Integrated In the resonance Ionization mass spectrometry technique (RIMS), have been evaluated as a tool for quantitative elemental Impurity analysis of SIMOX (separation by Implanted oxygen), a new silicon-based material prepared by oxygen Implants. The vanadium impurity content was measured In the top crystalline SIMOX film and the oxygen-synthesized burled oxide layer In commercial wafers, resulting In 0.14 gg/g ± 20%, or 1.7 X 101S atoms/cm3. A similar analysis on the substrate bulk shows about 30 times lower vanadium Impurity levels. The origin of this contamination may be linked to the oxygen Implant, although no modeling for It Is offered here. The sensitivity of RIMS to vanadium is In the pg/g range. The accuracy of results Is limited by the uncertainty In the blank, In view of the low total vanadium content In the specimen.