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Reliability and yield of nano-electronic devices can be seriously affected by the presence of surface contamination, even at low concentration. The microelectronics industry is, thus, in need for a quantitative, highly sensitive surface analysis technique capable of detecting both elementary and molecular species present at the surface. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) provides a submicronic lateral resolution and excellent sensitivity with high secondary ion yields on a broad mass range but, nevertheless, remains a qualitative technique. To convert normalized ion intensities into concentrations and, thus, to provide reliable quantification, the so-called relative sensitivity factors (RSFs) need to be determined. In earlier studies, ToF-SIMS RSFs for trace metals were determined from the calibration of ToF-SIMS positive ion intensities against quantitative analysis techniques able to determine a surface coverage such as vapour phase decomposition inductively coupled plasma mass spectrometry (VPD-ICP-MS) or total reflection X-ray fluorescence (TXRF) results. Here, the aim is to quantify elementary anionic minority species (S, Cl, P, Br). Deliberately contaminated samples were prepared and analyzed with ToF-SIMS and several quantitative surface analytical techniques like TXRF, liquid phase extraction ionic chromatography (LPE-IC) or VPD-ICP-MS. None of these latter techniques can by itself successfully handle all the anionic species cases and ToF-SIMS turns out to be the more versatile and precise characterization technique in this context.

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) has previously been successfully applied to characterize the covalent grafting of N-(m-(3-(trifluoromethyl) diazirine-3-yl)phenyl)-4-maleimido-butyramide (MAD), a reagent used for immobilization of biomolecules on solid surfaces, i.e., diamond substrates. In this study, the molecule was used to compare dose-related damage data obtained on two different ToF-SIMS systems, a PHI Trift and a PHI-7200 Reflectron, after shipping identically prepared samples to two independent laboratories. The ToF-SIMS spectrum in the negative ion mode exhibits characteristic signals over a large mass range, allowing to compare spectral differences in data acquired in the static SIMS regime with the two spectrometers to differences in experimental parameters, such as detector voltages. Variations in ion beam damage were not fully reproduced by both ToF-SIMS systems, indicating limitations in the comparison of ion beam damage data using two different sets of experimental parameters. This discrepancy could be related to different mass-dependent ion transmissions of the two spectrometers. The results suggest that a model developed in the literature for the interpretation of ion dose-induced polymer damage can be successfully applied to the case of organic molecules covalently attached to a diamond surface.

Recent time-of-flight secondary ion mass spectrometry studies using primary ion cluster sources such as Aun+, SF5+, Bin+ or C60+ have shown the great advantages in terms of secondary ion yield enhancement and ion formation efficiency of polyatomic ion sources as compared to monoatomic ion sources like the commonly used Ga+. In this work, the effective gains provided by such a source in the static ToF-SIMS analysis of microelectronics devices were investigated. Firstly, the influence of the number of atoms in the primary cluster ion on secondary ion formation was studied for physically adsorbed di-isononyl phthalate (DNP) (plasticizer) and perfluoropolyether (PFPE). A drastic increase in secondary ion formation efficiency and a much lower detection limit were observed when using a polyatomic primary ion. Moreover, the yield of the higher mass species was much enhanced indicating a lower degree of fragmentation that can be explained by the fact that the primary ion energy is spread out more widely, or that there is a lower energy per incoming ion. Secondly, the influence of the number of Bi atoms in the Bin primary ion on the information depth was studied using reference thermally grown silicon oxide samples. The information depth provided by a Bin cluster was shown to be lowered when the number of atoms in the aggregate was increased.