Ultrapure Process Chemicals Analysis by ICP-QQQ with Hot Plasma Conditions

Significance of the Topic

Contamination control is essential in semiconductor manufacturing, where even trace metal impurities in ultrapure water (UPW) can compromise device performance and yield. UPW directly contacts wafer surfaces during critical cleaning steps, making its purity a key factor in preventing defects and ensuring reliable electrical properties in semiconductor devices.

Objectives and Study Overview

This study evaluates the performance of the Agilent 8900 triple quadrupole ICP-MS (ICP-QQQ), equipped with an optional microlens (m-lens) and operated under hot plasma conditions, for detecting single- and sub-ppt levels of 26 ASTM/SEMI-specified elements in UPW. The goal is to demonstrate that hot plasma, combined with MS/MS modes, achieves detection limits and background equivalent concentrations (BECs) that comply with industry guidelines.

Methodology and Instrumentation

A mixed multi-element standard was added to acidified UPW (0.1% HNO₃) for method of standard addition calibrations at 5, 10, 20, and 40 ppt. The 8900 ICP-QQQ used no-gas, ammonia+hydrogen reaction, and oxygen reaction gas modes in a single multitune sequence controlled by MassHunter software. The optional m-lens and Pt-tipped Ni skimmer cone enabled robust ion transmission under hot plasma (RF power 1600 W, CeO⁺/Ce⁺ < 2%) while MS/MS operation (Q1 and Q2 around the ORS4 cell) removed spectral interferences.

Key Results and Discussion

Representative calibration curves for K, Ca, Fe, and Ni exhibited excellent linearity (r>0.999) without background subtraction. BECs and detection limits for 25 elements were below 0.5 ppt and 0.3 ppt, respectively, meeting ASTM D5127-13 and SEMI F63-0521 requirements. Boron, with a higher guideline of 50 ppt, achieved a BEC of 1.11 ppt and DL of 1.18 ppt—far below limits. The method effectively resolved argon-based interferences (Ar⁺, ArH⁺, ArO⁺), enabling sub-ppt analysis of ⁴⁰Ca, ³⁹K, and ⁵⁶Fe under hot plasma.

Benefits and Practical Applications

• The hot plasma approach simplifies workflow by eliminating the need for separate cool-plasma setups.
• MS/MS reaction modes with ammonia/hydrogen and oxygen gases ensure interference-free analysis across a broad element range.
• Standard addition calibration in UPW provides accurate quantification of trace contaminants.
• The method supports quality control in semiconductor fabs, reagent suppliers, and analytical laboratories.

Future Trends and Potential Uses

Advances may include further automation of gas mode switching and data processing, extension of the hot plasma MS/MS approach to other high-purity chemicals and complex matrices, and integration with process analytics for real-time contamination monitoring. Emerging cell gas chemistries and improved lens designs will continue to enhance detection capabilities at ultratrace levels.

Conclusion

The Agilent 8900 ICP-QQQ with an optional m-lens, operated under hot plasma MS/MS conditions, reliably measures 26 SEMI critical elements in UPW at single- and sub-ppt levels. The method meets or exceeds ASTM and SEMI guidelines, demonstrating its suitability for stringent semiconductor contamination control.

Instrumentation Used

Agilent 8900 SEMICONDUCTOR Configuration ICP-QQQ with ORS4 collision/reaction cell, PFA-100 MicroFlow nebulizer, quartz spray chamber, quartz torch (2.5 mm injector), Pt-tipped Ni skimmer cone, optional m-lens, and MassHunter control software.

References

1. Agilent Technologies, Applications of ICP-MS: Measuring Inorganic Impurities in Semiconductor Manufacturing, publication 5991-9495EN.
2. ASTM D5127-13 (2018), Standard Guide for Ultra-Pure Water Used in the Electronics and Semiconductor Industries.
3. SEMI F63-0521 (2021), Guide for Ultrapure Water Used in Semiconductor Processing.
4. K. Yamanaka, Determination of Ultratrace Elements in High Purity Hydrogen Peroxide with Agilent 8900 ICP-QQQ, publication 5991-7701EN.
5. Y. Yu, Analysis of Ultratrace Impurities in High Silicon Matrix Samples by ICP-QQQ, publication 5994-2890EN.
6. Agilent Technologies, Technical Overview of Agilent 8900 Triple Quadrupole ICP-MS, publication 5991-6942EN.
7. N. Sugiyama and K. Nakano, Reaction Data for 70 Elements Using O₂, NH₃ and H₂ with the Agilent 8800 Triple Quadrupole ICP-MS, publication 5991-4585EN.