Getting fast, accurate measurements on the performance of additives used in semiconductor electroplating baths is of critical importance in providing plating quality which includes uniformity, brightness, and consistency. Liquid chromatography with charged aerosol detection (CAD) and electrochemical detector techniques ensures reliable plating by detecting individual components, their byproducts, and other components in process monitoring applications. The technique has been successfully applied to the determination of individual organic additives in acid copper and nickel plating baths.
I am pleased to present a recently released method, developed by our scientists in collaboration with scientists from Seagate Technologies, titled, Measurement and Control of Copper Additives in Electroplating Baths by High-Performance Liquid Chromatography (downloadable PDF). The application note provides a comparative analysis of various additives, such as accelerators, levelers, and suppressors, using CVS and liquid chromatography using one of our HPLC systems (Thermo Scientific UltiMate HPLC system) with CAD and electrochemical detectors.
The HPLC technique provides advantages over the cyclic voltammetric stripping (CVS) technique which is a widely used technique to measure the combined effect of additives and by-products on the plating quality. However, CVS is not able to readily detect individual components, their by-products, or other compounds that are not electrochemically active. The net effect is CVS indicates an additive component is no longer performing, but not which one. Figure 1 is a chromatogram showing the results of HPLC-CAD analysis of accelerator and suppressor at concentrations ranging from 12.5–200% nominal concentration, each concentration analyzed in triplicate.
The HPLC methods for the determination of accelerator, leveler, and suppressor organic additives in acid copper plating baths provide reliable and fast determinations of the levels of these organic additives. Unlike CVS methodology that shows a cumulative signal related to all of the additives and their impurities, actual quantities of additives can be reliably obtained.
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Paul Voelker is a marketing manager for the Environmental and Industrial Markets in the Chromatography and Mass Spectrometry Division at Thermo Fisher Scientific Inc.He is responsible for creating and executing global marketing strategies, campaign development, and vertical content that align with corporate, product marketing, and regional marketing strategies and deploy them through digital and social media channels. Activities include combining a deep understanding of VOC processes and applications with product knowledge and new regulatory methods development to provide complete workflow solutions to target markets. Paul has over 25 years of experience in market development, marketing management, and lab applications in Life Science, Pharma/Biopharma, Environmental, and Industrial markets.He holds a B.S. in Chemistry from Cal State University at Hayward, and a M.S. in Chemistry from the University of California at Davis and has 7 publications and 7 patents to his credit.