Analysis of Nanoparticles in Organic Reagents by Agilent 8900 ICP-QQQ in spICP-MS Mode

Significance of the topic

Accurate detection of metallic nanoparticles in semiconductor manufacturing reagents is critical to avoid wafer defects and yield loss. Even trace levels of iron-based particles can cause cone defects and electrical shorting, emphasizing the need for a sensitive, interference-free analytical technique.

Objectives and Study Overview

This study evaluates the use of single particle ICP-MS (spICP-MS) on an Agilent 8900 triple quadrupole ICP-MS operating in MS/MS mode to determine 25 and 30 nm Fe3O4 nanoparticles in low-particle concentration solutions of isopropyl alcohol (IPA), propylene glycol methyl ether acetate (PGMEA), and butyl acetate (BuAc). Key goals included size characterization, particle number concentration measurement, and assessment of long-term stability.

Methodology

Sample Preparation:

• Fe3O4 nanoparticle standards (25 nm and 30 nm) spiked into IPA, PGMEA, and BuAc.
• Preparation of ionic Fe standards by diluting a 1000 ppm Fe solution in each solvent for calibration of ionic sensitivity.
• Direct introduction of organic solvents into the ICP-QQQ with oxygen addition to the sample gas to prevent carbon deposition.

Data Acquisition and Processing:

• Operation in MS/MS mode with Q1 and Q2 both set to m/z 56 to select Fe ions and remove spectral interferences using NH3 reaction chemistry.
• Fast time resolved analysis at 100 µs dwell time over 60 s acquisition to capture single-particle signals.
• Data processed using the Single Nanoparticle Application Module in MassHunter software for threshold setting, size, and count determination.

Used Instrumentation

• Agilent 8900 Triple Quadrupole ICP-MS in semiconductor configuration with MS/MS operation.
• Agilent SPS 4 autosampler with continuous rinse system and PFA nebulizer (self-aspiration).
• Quartz spray chamber and torch with 1.5 mm i.d. injector and platinum-tipped cones.
• Option gas mass flow controllers delivering O2 (20% in Ar) and NH3 (10% in He) into the collision/reaction cell.

Main Results and Discussion

• 30 nm Fe3O4 nanoparticles spiked at 5 ppt in IPA, PGMEA, and BuAc show clear separation of particle signals from background, with measured mean sizes around 30 nm.
• Nebulization efficiency calculated by size was approximately 30% across all solvents.
• Ionic Fe sensitivity ranged from 1500 to 2400 cps/ppt; background equivalent diameter of blanks was around 6 nm.
• Linearity (R2 = 0.998) demonstrated for 25 nm Fe3O4 nanoparticles spiked between 0.1 and 2 ppt in IPA.
• Long-term stability tests over 12 hours showed consistent particle number concentration and size (%RSD within acceptable limits) in all three solvents.

Benefits and Practical Applications

This spICP-MS method on the Agilent 8900 provides low detection limits, high sensitivity, and effective removal of spectral interferences, making it suitable for quality control of semiconductor-grade chemicals and ensuring reliable device fabrication.

Future Trends and Potential Applications

• Expansion to multi-element nanoparticle analysis by leveraging QQQ capabilities for simultaneous detection of various metal NPs.
• Integration with inline process monitoring to detect nanoparticle contamination in real time.
• Application to emerging nanomaterials and other industrial reagents requiring high-purity specifications.

Conclusion

The study confirms that spICP-MS using an Agilent 8900 ICP-QQQ in MS/MS mode effectively determines and characterizes iron oxide nanoparticles in low-concentration organic solvents, with reliable sensitivity, linearity, and temporal stability.

References

1. Hagiwara T. et al. Study on cone-defects during the pattern fabrication process with silicon nitride. Journal of Photopolymer Science and Technology. 2015;28(1):17–24.
2. Yamanaka M., Wilbur S. Measuring multiple elements in nanoparticles using spICP-MS. Agilent Technologies. Publication 5994-0310EN.
3. Shimamura Y., Hsu D., Yamanaka M. Multielement nanoparticle analysis of semiconductor process chemicals using spICP-QQQ. Agilent Technologies. Publication 5994-0987EN.
4. Yamanaka M., Wilbur S. Accurate determination of TiO2 nanoparticles in complex matrices using the Agilent 8900 ICP-QQQ. Agilent Technologies. Publication 5991-8358EN.