The effect of powder particle size on the corrosion behavior of atmospheric plasma spray-Y2O3 coating: Unraveling the corrosion mechanism by fluorine-based plasma

[Display omitted] •As the powder particle size of the APS coating decreases, the density of the microstructure increases.•Surface YOxFy layer creation and etching by physical (ion bombardment) and chemical (radical) reaction.•Plasma corrosion resistance improved with increasing density of APS-Y2O3 coating.•Reduced contaminant particle generation through APS coating powder particle control. The atmospheric plasma spray (APS) -Y2O3 coatings are widely used to minimize damage to internal parts of the chamber caused by the strong corrosive effect of fluorine-based plasma used in dry etching; however, the poor density of APS-Y2O3 coatings results in low plasma corrosion resistance. This is a major cause of the generation of contamination particles during CF4/O2 plasma etching. Hence, defects inside the coating must be eliminated to improve the plasma corrosion resistance of APS-Y2O3 coatings. The correlation between the decrease in the number of defects inside the APS-Y2O3 coatings according to the powder particle size and the surface corrosion process by CF4/O2 plasma etching was confirmed. We verified that the internal defects in APS-Y2O3 coatings can be controlled with small powder particles because the powder particles in the APS layer melt efficiently under the APS coating conditions; in addition, the fluorine content rate inside the coating is improved. After the focused ion beam (FIB) process, by examining YOxFy layer with a field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS); we observed the formation of a thick YOxFy layer with decreasing number of defects inside the APS-Y2O3 coatings; thereby, the bonding strength among the Y2O3 powder particles was increased, and corrosion of YOxFy layer due to physical and chemical reactions decreased; as a result, the etch amount was significantly reduced. Therefore, it can be seen that the generation of contamination particles in the CF4/O2 plasma etching can be reduced by controlling the occurrence of defects inside the APS-Y2O3 coatings. The results of this study demonstrate the possibility of minimizing the effect of contamination particles generated in the dry etching process to remove YOxFy layer using chamber self-cleaning such as waferless step. This paper presents a new direction for controlling contamination particles in the inner coating parts of the plasma etching chamber.