WCPS: The Analysis and Stability of High Purity TetraMethylAm m onium Hyrdoxide (TMAH) with the Agilent 8900 QQQ-ICPMS

Importance of the Topic

Tetramethylammonium hydroxide (TMAH) is a critical reagent in semiconductor manufacturing, serving as a silicon etchant and photoresist stripper. As device dimensions shrink, the purity of TMAH and the ability to detect trace metal contaminants become vital to maintain wafer integrity, process yield, and overall product performance.

Objectives and Study Overview

This study evaluates the stability of a fivefold dilution of 25 % TMAH solution over an 18 hour period and demonstrates the analytical performance of the Agilent 8900 triple quadrupole ICP-MS. Twenty-four elements were spiked at 10 ppb into the diluted TMAH to monitor normalized signal responses and to determine detection limits under a heavy matrix.

Methodology and Instrumentation

A semiconductor-grade 25 % TMAH solution was diluted 5:1 (w/v) and spiked with 24 target elements at 10 ppb each. Continuous measurements were carried out over 18 hours using the Agilent 8900 QQQ-ICP-MS operating in MS/MS mode with Universal Helium Mode (UHMI) conditions. All ion optics, RF power, gas flows, and kinetic energy discrimination settings were automatically optimized using the UHMI-25 tune.

Used Instrumentation

Agilent 8900 QQQ-ICP-MS configured with:

• Quartz double‐pass spray chamber
• Quartz concentric nebulizer
• Quartz torch with 2.5 mm injector
• UHMI collision/reaction cell technology

Analytical parameters such as sample depth, carrier gas flow, cell gas flow, and RF power were set by the UHMI-25 software routine.

Results and Discussion

All 24 elements maintained normalized signal responses within ±20 % of initial values over 18 hours, confirming matrix stability. Calibration plots for selected elements (Na, Al, K, Cr, Fe, Co, Ni, Cu, Ga) revealed detection limits in the sub-ppt to low-ppt range and low background equivalent concentrations. These findings illustrate that the Agilent 8900 can handle a heavy TMAH matrix without sacrificing sensitivity or precision.

Benefits and Practical Applications

The demonstrated robustness and low detection limits of the Agilent 8900 QQQ-ICP-MS support stringent quality control in semiconductor fabs. Reliable trace‐metal analysis in TMAH enables manufacturers to detect potential contaminants early, minimizing wafer defects and improving yield.

Future Trends and Opportunities

Future developments may include automated sample handling, inline process monitoring, and enhanced data analytics to further accelerate throughput and reduce manual intervention. Advances in collision/reaction cell chemistries and instrument automation will expand the application of triple quadrupole ICP-MS in semiconductor process control and environmental compliance.

Conclusion

The Agilent 8900 QQQ-ICP-MS delivers stable, accurate, and sensitive analysis of trace metals in high‐purity TMAH over extended periods. Its performance makes it a valuable tool for contamination control in advanced semiconductor manufacturing.

Reference

Woods B.; Kelinske M. The Analysis and Stability of High Purity Tetramethylammonium Hydroxide (TMAH) with the Agilent 8900 QQQ-ICP-MS. 2018 Agilent Technologies Poster #Th36.