Methane-assisted plasma-wet local scrubber (MAPWLS) for efficient nitrous oxide removal from semiconductor manufacturing emissions

• CH₄-assisted arc plasma effectively mitigates N₂O emissions from semiconductor processes. • CH₄ injection significantly enhances N₂O destruction and suppresses NOₓ by-products. • DRE improved from 38.5 % to 90.6 % with optimal CH₄ flow rates (0.4–0.5 L/min). • CHEMKIN-PRO simulations reveal CH₄-derived radicals promote NO reduction pathways. • This plasma–CH₄ system offers scalable, high-efficiency control of greenhouse gases. Nitrous oxide (N₂O), a potent greenhouse gas emitted during semiconductor manufacturing, poses serious environmental challenges. This study proposes a methane-assisted plasma-wet local scrubber (MAPWLS) for effective N₂O abatement. The core innovation involves injecting methane (CH₄) into an arc plasma system, which not only enhances N₂O decomposition but also minimizes nitrogen oxides (NOₓ) formation. Experimental evaluations and CHEMKIN-PRO kinetic simulations were used to analyze performance under various conditions. Without CH₄, increasing nitrogen (N₂) flow from 100 to 150 standard liter per minute (slpm) reduced N₂O destruction and removal efficiency (DRE), while plasma currents above 50 ampere suppressed nitric oxide (NO) generation. With CH₄ addition, DRE markedly improved from 38.5 % to 90.6 % as CH₄ flow increased from 0 to 0.4 slpm at 150 slpm N₂. The optimal CH₄/N₂ ratio ranged from 0.2 % to 0.27 %, balancing efficiency and by-product suppression. Furthermore, CH₄ effectively reduced NO, with NO/N₂O ratios dropping from 10 % to 1 % at 0.75 slpm CH₄. Kinetic modeling revealed that CH₄-derived radicals enhance NO oxidation and reduction, reducing NOₓ levels. However, excessive CH₄ promotes NNH formation, potentially regenerating N₂O and diminishing net abatement. An optimal CH₄ flow of 0.4–0.5 slpm and a CH₄:N₂O ratio of 20–25 % is recommended for maximizing DRE while minimizing NOₓ. The MAPWLS demonstrates a scalable, high-efficiency strategy for mitigating N₂O emissions in semiconductor processes. The mechanistic insights provide a foundation for advanced NOₓ control technologies applicable across industrial emission systems.