Investigation of contamination particles generation and surface chemical reactions on Al2O3, Y2O3, and YF3 coatings in F-based plasma

Al and Y compounds are coated on the surfaces of chamber internal parts to prevent damage from the strong corrosiveness of plasma. Internal parts exposed to plasma for long periods generate defects and contamination particles, and understanding the principles of their generation is crucial to damage and contamination prevention. This study investigates the behavior and surface chemical reactions of contamination particles generated from plasma damage on Al2O3, Y2O3, and YF3 coatings applied through anodizing and atmospheric plasma spray. Changes in the surface roughness of these coatings were found to be higher for anodizing than atmospheric techniques when exposed to NF3/Ar/O2 plasma. X-ray photoelectron spectroscopy and optical emission spectroscopy revealed that fluorination was induced by F radicals on a surface of oxide coating. Conversely, the YF3 coating remained chemically stable in the F plasma because of Y-F bonding. Light-scattering sensor analysis indicated that the YF3 coating produces fewer contamination particles than the oxide coating.