Hydrogen peroxide concentration monitoring for CMP slurry

CMP slurry contains abrasive and pH adjuster, and in many cases Hydrogen Peroxide (H₂O₂) is added as an oxidizer. In order to stabilize the process, H₂O₂ concentration is one of the critical factors, and Redox titration is generally used for H₂O₂ monitoring. However, titration method requires time, labor and consumables for sampling, pretreatment and titration itself with reagent, and it is not suitable for real-time monitoring. In this paper, the results of applying near infrared (NIR) and ultraviolet (UV) absorption spectroscopy and multivariate analysis for in-line H₂O₂ monitoring is reported.