Analysis of 15 nm Iron Nanoparticles in Organic Solvents by spICP-MS

In semiconductor device manufacturing, even small amounts of impurities present in processing reagents can affect product yield and reliability. There is growing awareness that metallic nanoparticles (NPs), especially Fe NPs, can lead to the occurrence of defects on the surface of wafers. Single particle ICP-MS (spICP-MS) is a powerful tool that is used increasingly to characterize the NP content of various types of samples, including semiconductor process chemicals.

For this analysis the Agilent 8900 ICP-QQQ (semiconductor configuration) was fitted with a quartz torch with a 1.5 mm i.d. injector. Interferences on 56Fe from ArO and C2O2 were resolved using oxygen as the cell gas. The Agilent SPS 4 autosampler was used, so large bottles (100 to 500 mL) could be used for long-term stability tests. The samples were self-aspirated using an Agilent PFA nebulizer with SPS 4 probe kit (G3139-68000). Data analysis was performed using the optional Single Nanoparticle Application module of Agilent ICP-MS MassHunter software.

The spICP-MS method was used to measure isopropyl alcohol (IPA), propylene glycol methyl ether acetate (PGMEA), and propylene glycol monomethyl ether (PGME) spiked with 15 nm Fe2O3 NPs (Sigma Aldrich). Figure 1 shows the signal distribution (upper) and size distribution plots (lower) for Fe NPs in each of the samples. The NP signals were clearly separated from the background signals. Also, the mean measured particle size was around 15 nm in all spiked samples, which is consistent with the nominal Fe NP diameter of 15 nm.

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