Calibration of secondary neutral and secondary ion mass spectrometry: A comparative study

The sensitivity and the dynamic range of a quadrupole based mass spectrometer for the quasisimultaneous analysis of secondary ions and electron beam postionized sputtered neutrals has been improved. Counting rates larger than 106 counts/s of postionized neutrals with a dynamic range of six orders of magnitude have been obtained for iron samples bombarded by 10-μA, Ar+, 5 keV. A comparison of secondary ion mass spectrometry (SIMS) and secondary neutral mass spectroscopy (SNMS) results considering target preparation, sensitivity, reproducibility, accuracy of quantification, and total time of analysis will be presented for 13 steel targets alloyed with up to 15 different elements. Concentration ranges between 8 ppm and 1% have been covered. From the experimental results we found that the detection limit is in the range of 10−4 (oxygen) of a monolayer on a target area of 4 mm2, when the spectrometer is tuned to a distinct mass. This allows quantitative surface and interface analysis in a concentration range below Auger electron spectroscopy.