Verifying PFAS Abatement in Fab-Relevant Waste Matrices Using Complementary Analytical Characterization Techniques
Per- and polyfluoroalkyl substances (PFAS) are integral components in photolithography processes and cleaning chemistries, but their continuous presence, variety, and low concentrations in fab waste effluents complicate analysis and abatement. These compounds are toxic, extremely mobile, and persistent, and migrate through water systems if not managed properly, thereby leading to long-term environmental contamination. Photoactivated reductive defluorination (PRD) is an effective abatement technique explored more recently for PFAS destruction, and representative wastes (e.g., developer and cleaning effluents containing photoresist-derived compounds and surfactants) can be treated using UV irradiation under controlled conditions. However, fab waste matrices can strongly reduce UV performance due to light attenuation, consumption of destructive radicals by matrix organics, and competitive reactions with salts, thereby leading to incomplete defluorination and formation of short-chain byproducts when a limited UV dose is applied. In addition, verification often relies on a limited target list that may overlook neutral PFAS, fluoropolymers, and transformation products. We present a complementary analytical characterization workflow that combines Fluorine-19 nuclear magnetic resonance (19F NMR) and High Resolution Mass Spectrometry (HRMS) to provide a comprehensive fluorine mass balance in fab waste matrices. HRMS provides robust quantitative analysis in ppt level as well as qualitative analysis, including nontarget screening of degradation products, while 19F NMR can provide detailed structural information and an overview of total inorganic and organic fluorine composition. This combined approach allows for an accurate and reliable abatement verification that highlights matrix-dependent limitations of PRD destruction and is not restricted to compound-specific analysis. Therefore, it can provide actionable metrics for improved PRD treatment process optimization and routine waste monitoring in fabs. This work presents practical strategies by utilizing this workflow as a sustainable metrology tool for PFAS management in semiconductor manufacturing.
BIOGRAPHY
I earned my PhD in Chemical Engineering from Oklahoma State University in 2023, with a focus on the green and sustainable synthesis of metal nanostructures. I also hold a master's and bachelor's in Chemical Engineering. I joined imec in 2024 as a postdoctoral researcher. In my current role, I study PFAS contaminants from semiconductor manufacturing (fab) waste for sustainable waste management approaches in the semiconductor industry. I investigate the identification and quantification of PFAS and their chemical fate from photolithography and general fab waste matrices using 19F NMR and mass spectrometry. My research aims to improve current analytical workflows, identify non-target compounds, and investigate the chemical fate of target and non-target compounds after relevant destruction processes, which can ultimately inform fabs on efficient abatement strategies for responsible waste management.