DETECTION OF METALLIC IMPURITIES BY RESONANCE IONIZATION MASS-SPECTROMETRY

A resonant ionization mays spectrometer based on a quadrupole SIMS cou pled to a turnable dye laser has been developed for the detection of t race amounts of metallic impurities in semi conductor materials. The a ppropriate wavelength to ionize various metals with one color, one res onance (1 + 1) process has been determined. The detection limit of the apparatus has been measured for chromium using different standards wi th known concentrations of impurities and a value of 0.2 ppm has been found. A study of different metals has shown that his result is nearly independent of the matrix. A depth profile with this instrument is pr esented for titanium in silicon.