In-situ electrochemical sensor for early detection of plating problems in copper metallization process

A system for plating bath process control was developed utilizing a novel approach that combines advanced electroanalytical methods with various statistical data analysis techniques based on chemometric factor analysis. All measurements and calculations were performed using instrumentation and software custom developed for this application. The electroanalytical techniques employed, including DC- and AC-voltammetry, were designed to provide a response strongly affected by the presence of contaminants and/or accumulated degradation products. The shape differences between deformed and training set voltammograms were quantified using various outlier-detection chemometric techniques. These differences were correlated with the plating performance of the bath and corresponding automatic warnings were established. The system was proven to be effective for a controlled bleed-and-feed process.