Measuring Inorganic Impurities in Semiconductor Manufacturing

Significance of the topic

Contamination by trace metallic and non-metallic impurities in semiconductor manufacturing can cause yield losses and device failures as feature sizes shrink to the nanometer scale. High-purity wafer substrates and process chemicals must be monitored with sub-ppt sensitivity. Inductively coupled plasma mass spectrometry (ICP-MS), especially triple quadrupole ICP-MS (ICP-QQQ) with MS/MS operation, provides the sensitivity, low background, and interference removal required for ultratrace analysis.

Objectives and overview of the article

This compendium reviews the application of single and triple quadrupole ICP-MS techniques across semiconductor processes. It covers substrate analysis via vapor phase decomposition (VPD), monitoring of ultrapure water and hydrogen peroxide, analysis of organic solvents (IPA, PGMEA, NMP), online chemical monitoring systems, contamination control strategies, nanoparticle detection by spICP-MS, and extension to hydride gas analysis using GC-ICP-QQQ.

Methodology and Instrumentation

Key methods include VPD wafer sampling coupled with self-aspirating nebulizers to extract and quantify surface metal residues. Cool plasma conditions combined with collision/reaction cell modes (He, H2, NH3, O2) on the Agilent 7900 and 8900 ICP-QQQ systems afford effective background suppression and interference removal. Inert PFA sample introduction kits allow analysis of corrosive and organic samples. Automated sample handling is implemented via the Agilent I-AS autosampler, ESI prepFAST S system, and IAS ASAS online standard addition module. Nanoparticles are characterized using fast time-resolved ICP-QQQ and the Single Nanoparticle Application for spICP-MS.

Main Results and Discussion

• Sub-ppt detection limits for 26 elements in ultrapure water and hydrogen peroxide using ICP-QQQ MS/MS with optimized cell gases and optional m-lens.
• Ultratrace analysis of high-matrix Si samples (10–100 ppm Si) with <6% RSD for 38 elements.
• Direct organics analysis: single-ppt DLs for Si, P, S, and Cl in NMP and methanol via mass-shift and on-mass modes.
• Automated MSA calibration in IPA by GC-ICP-QQQ yields sub-ppt DLs for hydride gas contaminants (PH3, GeH4, H2S, etc.) with DLs down to <0.1 ppb.
• Nanoparticle spICP-MS in TMAH, IPA, PGMEA, BuAc: detection of 15–30 nm Fe, Al2O3, Ag, Au, SiO2 NPs with stable size and count over 12 hours.

Benefits and Practical Application of the Method

• Improved sensitivity and reliability via ICP-QQQ MS/MS for semiconductor chemicals, wafers, and gases.
• Automated sample preparation and calibration reduce analyst skill requirements, contamination risk, and errors.
• Multi-tune acquisition supports simultaneous measurement of trace elements in diverse matrices.
• spICP-MS extends ICP-QQQ capability for characterization of metallic nanoparticles.

Future Trends and Possibilities

• Further automation of online process chemical monitoring for real-time contamination control.
• Wider adoption of spICP-MS for multielement nanoparticle surveys in manufacturing streams.
• Expansion of GC-ICP-QQQ for other hydride and volatile organometallic contaminants.
• Integration with field-deployable systems for at-line quality assurance.

Conclusion

Advances in ICP-QQQ technology, combined with specialized sample introduction, cool plasma, CRC modes, and MS/MS operation, enable ultratrace analysis of metals and non-metals in complex semiconductor matrices. Automation of sample handling and calibration streamlines workflows, reduces error, and ensures high data quality. These methods support stringent contamination control required for next-generation devices.

References

• ASTM D5127-13, Guide for Ultra-Pure Water Used in Electronics and Semiconductor Industries
• SEMI F63-0521, Guide for Ultrapure Water Used in Semiconductor Processing
• SEMI C30-1110, Specifications for Hydrogen Peroxide
• SEMI C27-0708, Specifications for Hydrochloric Acid
• SEMI C41-0705, Specifications and Guidelines for Isopropyl Alcohol
• Geiger W.M. and Raynor M.W., Trace Analysis of Specialty and Electronic Gases, Wiley, 2013