Reduced amount of contamination particle generated by CF4/Ar/O2 plasma corrosion of Y2O3 materials: Influence of defluorination process

Abstract

Y2O3 coatings during atmospheric plasma spray (APS) processes are used to suppress the corrosion of internal process chamber parts for semiconductor plasma etching. Highly corrosive fluorine-based plasma corrodes the surface, causing contamination particle and process drift, which are the main causes of yield reduction. In this paper, defluorination is proposed to reduce the amount of contamination particle generation by removing the YOxFy layer on the surface of APS-Y2O3 material after plasma etching. After exposure to CF4/Ar/O2 plasma, chemical–mechanical polishing occurred using KOH, surfactant, and piranha solutions, respectively. The highest and lowest defluorination efficiencies were obtained with the piranha and surfactant solutions, respectively. The results were validated by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. In particular, the piranha solution generated the lowest amount of contamination particles and lowest amount of etching. In contrast, the thickness reduction due to the defluorination process resulted in the highest breakdown voltage among the surfactant solutions, thereby prompting optimization studies. Finally, the mechanisms of the plasma etching and defluorination processes were derived, and a new method for controlling the amount of contamination particle generation was presented.