This application note demonstrates the suitability of a newly developed, high sensitivity reaction cell inductively coupled plasma mass spectrometer (ICP-MS) for the determination of inorganic impurities in semiconductor grade sulfuric acid. The Agilent 7500cs ICP-MS, featuring a high sensitivity version of the Octopole Reaction System (ORS), was used to analyze sulfuric acid for all the metals required by the semiconductor industry. The enhanced ORS eliminates all plasma and matrix based polyatomics that interfere with the measurement of elements such as K, Ca, Ti, Cr, Fe, Co, Ni, Cu, and Zn while offering excellent ion transmission and sensitivity. Furthermore, all analytes can be measured at high plasma power to promote complete decomposition of the sulfuric acid in the plasma. This leads to high signal stability and a reduced frequency of routine maintenance. Sample preparation is a simple 10x dilution followed by direct analysis thereby significantly reducing the potential for the sample contamination frequently encountered with evaporative matrix elimination techniques.
The document details a method using the Agilent 7500cs Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to analyze inorganic impurities in semiconductor-grade sulfuric acid. The analysis utilizes the high-sensitivity Octopole Reaction System (ORS) with hydrogen and helium gases to eliminate matrix-based polyatomic interferences that typically affect elements like Titanium, Copper, and Zinc.
Sample preparation involves a simple 10x dilution of concentrated sulfuric acid with ultrapure deionized water, followed by direct analysis. This approach avoids the contamination risks associated with evaporative matrix elimination techniques. The study reports detection limits (DLs) and Background Equivalent Concentrations (BECs) for various SEMI elements, demonstrating excellent performance even at high plasma power settings.
The concentrated sulfuric acid must be diluted ten times with ultrapure deionized water before analysis.
All applications and measurements are performed at an RF power of 1600W.
A cell gas flow rate of 5 mL/min is used in both hydrogen and helium modes.