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

Significance of the Topic

The accumulation of metal nanoparticles in semiconductor processing fluids can compromise wafer integrity and yield. Monitoring iron nanoparticle contamination at the nanoscale is critical for process control, quality assurance, and defect mitigation in device fabrication.

Objectives and Study Overview

This study demonstrates the application of single particle ICP-MS (spICP-MS) using an Agilent 8900 ICP-QQQ system to quantify and size 15 nm iron nanoparticles in high-purity organic solvents relevant to semiconductor manufacturing. The focus is on method validation, stability assessment, and signal accuracy.

Methodology and Instrumentation Used

• Instrumentation: Agilent 8900 ICP-QQQ (semiconductor configuration) equipped with a quartz torch (1.5 mm i.d.) and PFA nebulizer (SPS 4 probe), an SPS 4 autosampler, and MassHunter software with Single Nanoparticle Application module.
  
• Interference Removal: Oxygen cell gas (0.38 mL/min) to resolve ArO and C₂O₂ interferences on 56Fe.
  
• Operating Conditions: RF power 1200 W; sampling depth 16 mm; nebulizer gas flow 0.75 L/min; makeup gas flow 0.5 L/min; optional O₂ (12 %) for carbon control; dwell time 100 µs; acquisition time 60 s; single quadrupole scan mode monitoring m/z 56.
  

Main Results and Discussion

• Signal and Size Distributions: Distinct spICP-MS signals for 15 nm Fe NPs in IPA, PGMEA, and PGME, with measured mean sizes near 15 nm consistent with nominal diameters.
  
• Short-term Stability: Over 10 h tests in IPA and PGMEA, particle count and size remained stable with ≤ 6 % RSD for counts and ≤ 3 % RSD for size.
  
• Long-term Stability: 30 nm Fe NPs in IPA showed consistent size distribution profiles after six months, confirming colloidal stability in organic solvent.
  
• Intensity Ratio Validation: The measured signal intensity ratio between 30 nm and 15 nm particles (8.44) closely matched the theoretical cubic diameter ratio (8), validating quantitative accuracy.
  

Benefits and Practical Applications

The demonstrated spICP-MS method delivers high sensitivity and low background for reliable detection, sizing, and quantification of iron nanoparticles in critical semiconductor process solvents. This approach supports stringent contamination control and process monitoring workflows in microelectronics manufacturing.

Future Trends and Potential Applications

• Extension to Additional Materials: Application of spICP-MS for other metallic and alloy nanoparticles in semiconductor and related industries.
  
• Automation and Online Monitoring: Integration of real-time sampling interfaces and automated data analysis for in-line quality control.
  
• Enhanced Resolution: Development of advanced cell gas chemistries and dwell time optimization to enable detection of sub-10 nm particles.
  
• Software Innovations: Implementation of machine learning algorithms for pattern recognition and rapid stability assessment in complex matrices.
  

Conclusion

The Agilent 8900 ICP-QQQ spICP-MS method provides robust, accurate, and stable measurement of 15 nm iron nanoparticles in high-purity organic solvents. Its high sensitivity, interference-free performance, and proven long-term stability make it a valuable tool for semiconductor contamination control.

Used Instrumentation

• Agilent 8900 ICP-QQQ with quartz torch (1.5 mm i.d.).
  
• Agilent PFA nebulizer with SPS 4 probe kit.
  
• SPS 4 autosampler.
  
• MassHunter ICP-MS software with Single Nanoparticle Application module.