Enhanced plasma resistance of uniform ALD-Y2O3 thin films for chamber components' coatings

This study presents a comprehensive investigation of yttria (Y2O3) thin films deposited via atomic layer deposition (ALD) and their plasma resistance characteristics. A liquid precursor, Y(EtCp)(2)(Pr-i-amd), and various reactants (H2O, O-3, and O-2 plasma) were used for the ALD process. We examined the structural and compositional characteristics before and after reactive ion etching through x-ray diffractometry, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy, high angle annular dark-field-STEM energy dispersive spectroscopy, scanning electron microscopy, and atomic force microscopy (AFM) analyses. Our findings revealed that the choice of reactant influences film composition and crystal phase. The O-3 and O-2 plasma produced cubic Y2O3 films, while H2O generated a dual-phase of monoclinic and cubic Y2O3. Notably, ALD-deposited Y2O3 films demonstrated superior plasma resistance compared to the sputtered films. In contrast to previous studies on Y2O3 coatings, which were primarily concerned with etching mechanisms related to surface topography and porosity, our analysis using AFM and x-ray reflectivity demonstrates that Y2O3 thin films deposited by ALD with O-3 and O-2 plasma reactant exhibit very low surface roughness and high density. To verify the variations in etch rate, XPS depth profile analysis was performed for the Y2O3 thin films after etching. Through the analysis, we propose that the removal of uniform and high-density Y2O3 films with CF4-based plasma is influenced primarily by the depth of fluorine interaction. This study will contribute to extending the lifetime of etching equipment parts and increasing device production yield by improving their plasma resistance and particle generation.