IMPROVED QUANTIFICATION IN SECONDARY-ION MASS-SPECTROMETRY DETECTING MCS+ MOLECULAR-IONS

Molecular secondary ions composed of a sample atom M and a resputtered Cs+ projectile (MCs+) are successfully used for the quantification of secondary-ion mass spectrometry (SIMS) data. For a variety of different specimens it is demonstrated that the yields of these rather ubiquitous species exhibit little or no dependence on sample composition (matrix effect) even in the presence of electronegative elements and are thus well suited for quantitative SIMS evaluation. Specifically, for series of binary and ternary systems (a-Si:H, a-SiGe:H, a-SiC:H, and HCN) composition independent relative sensitivity factors could be established; thus, quantification by means of a single standard is feasible. Furthermore, from the correlation of the measured MCs+ secondary ion intensities relative sensitivity factors (and hence concentrations) can directly be derived, i.e., without any standard. The applicability of this quantification scheme is exemplified for a AlGaAs/GaAs multilayer structure and for the Ga focused ion beam implantation in InP. The results indicate that utilizing MCs+ molecular ions an accurate quantification of major components by SIMS is possible.