WCPS: Particle Analysis of Two High Purity Grades of N-Methyl-2- Pyrrolidone (NMP) using Single Particle (sp)ICP-MS/MS Method

Significance of the Topic

Advanced semiconductor manufacturing is highly sensitive to nanoparticle contamination in process chemicals. Trace metal nanoparticles in N-Methyl-2-pyrrolidone (NMP) can impair yield, reliability, and performance of devices with nanometre-scale features. Single particle ICP-MS/MS provides a powerful tool for rapid, multi-element particle detection and quantification, supporting stringent quality control in fabs.

Objectives and Overview

This study aimed to compare two high-purity NMP grades (EL for electronics, SP for supreme purity) by characterizing their nanoparticle content. Key goals included determining particle size distributions, elemental composition, and concentration differences between the grades, and validating the performance of the Agilent 8900 ICP-QQQ in spICP-MS mode.

Methodology and Instrumentation

The spICP-MS/MS method used time-resolved acquisition (TRA) at 0.1 ms integration to detect pulses from individual nanoparticles. Fourteen target elements were selected after background screening. Spectral interferences for critical elements (Mg, Al, Cr) were controlled via MS/MS reaction chemistry in the ORS4 collision-reaction cell, using gases such as NH₃, H₂, He and O₂. Data processing employed Agilent ICP-MS MassHunter software revision 5.2 with the Rapid Multi-Element Nanoparticle Analysis module.

Used Instrumentation

• Agilent 8900 ICP-QQQ (semiconductor configuration) with ORS4 cell
• Agilent I-AS autosampler
• ICP-MS MassHunter software version 5.2

Main Results and Discussion

Nebulization efficiency was determined as 19.6% using a SiO₂ nanoparticle reference. Method validation with a 25 nm Fe₃O₄ standard yielded a measured particle mass of 40 attograms, in close agreement with the theoretical 42 attograms. Size distribution analysis showed that the SP grade contained fewer and generally smaller particles across elements Mg, Al, Ca, Mn, Fe and Cu compared to the EL grade. Quantitative TRA data revealed Fe particle concentrations of 69 pg/L in SP NMP and 2.7 ng/L in EL NMP, with EL particles mainly 20–30 nm in size. Detected elements such as Fe, Cr and Ni suggest contamination sources like stainless-steel equipment.

Benefits and Practical Applications

• Combined nanoparticle and dissolved metal analysis in a single run delivers comprehensive quality assessment.
• High sensitivity and ultralow background enable detection at sub-ppt levels.
• Fast TRA acquisition supports multi-element monitoring without compromise on signal fidelity.
• Elemental fingerprints of particles aid in tracing contamination sources in semiconductor processes.

Future Trends and Potential Applications

Further developments in spICP-MS/MS software and hardware may expand the number of elements monitored simultaneously and improve lower size limits below 10 nm. Integration with automated sampling systems and real-time data analytics could enable inline monitoring of process chemicals. Applying similar workflows to other high-purity solvents and complex matrices will enhance contamination control across microelectronics and advanced manufacturing.

Conclusion

The Agilent 8900 ICP-QQQ in spICP-MS mode provides a robust and sensitive solution for nanoparticle characterization in high-purity NMP. Its capacity for multi-element, time-resolved analysis under controlled reaction conditions supports stringent contamination monitoring in semiconductor fabs, distinguishing between purity grades and informing corrective actions.

References

1. FUJIFILM Wako Pure Chemical Corporation. High-purity Solvent and Acid, EL grade NMP. 2. FUJIFILM Wako Pure Chemical Corporation. High-purity Solvent and Acid, SP grade NMP. 3. Shimamura Y., Kondo S. Elemental and Particle Analysis of N-Methyl-2-Pyrrolidone (NMP) by ICP-QQQ, Agilent publication 5994-5365EN.