LIMITS OF QUANTITATIVE MICROANALYSIS USING SECONDARY ION MASS SPECTROMETRY.

The limitations on secondary ion microanalytical performance imposed by ionization probabilities, mass spectrometer transmission, requirements for standards and sputtering artifacts have been investigated. The sensitivity of a modern magnetic mass spectrometer for sputtered B** plus from oxidized Si is approximately equals 10** minus **2 ions detected/atom sputtered. For this sensitivity, it is shown that ion microscopy of a part-per-million impurity is limited in lateral resolution to approximately equals 1 mu m. For a 1% impurity, lateral resolution of approximately equals 30 nm is achievable. Depth profile analysis at the ppm level requires sample areas approximately equals 10 mu m**2. Isotope abundance determinations in volumes approximately equals 1 mu m**3 require the concentration of the least-abundant isotope to be greater than equivalent to 1%.