Enhanced etching resistance of Y2O3 films through microstructure control via thermal annealing

Y 2 O 3 films with enhanced etching resistance were fabricated on silicon substrates using RF magnetron sputtering followed by vacuum annealing at 300 °C, 600 °C, and 900 °C. The films were systematically evaluated under chemical, mixed, and physical plasma etching environments using CF 4 /Ar/O 2 gas mixtures. Annealing at 900 °C transformed the microstructure from quasi-circular grains to densely packed polygonal grains with layered stacking, significantly improving the structural compactness of film. Y 2 O 3 films demonstrated superior etching resistance compared to conventional materials including Al 2 O 3 , SiC, AlN, and quartz. The 900 °C-annealed film under vacuum showed highest resistance under chemical and mixed etching, while the 600 °C-annealed film under vacuum performed best under physical etching due to superior hardness (7.2 ± 2.0 GPa). Nanomechanical testing revealed that physical etching resistance correlates with hardness, while chemical and mixed etching resistance depends on the structural compactness of film. Nano-indentation and nano-scratch testing showed that coatings annealed in air were softer and less scratch-resistant than those annealed in vacuum, with differences being more pronounced in statistically distributed nano-scratch testing. X-ray photoelectron spectroscopy confirmed distinct mechanisms: chemical etching involves protective Y F bond formation, mixed etching shows enhanced Y F stability, and physical etching induces oxygen vacancies. This study establishes a cost-effective strategy for enhancing etching resistance through microstructural optimization, offering promising implications for semiconductor manufacturing applications. • Y 2 O 3 film etching resistance enhanced by microstructure control via annealing • Vacuum annealing at 900 °C increased film density, improving resistance. • Y 2 O 3 film showed superior etching resistance to common materials. • Physical etching resistance correlated with film hardness, optimal at 600 °C • Statistically-distributed nano-scratch testing revealed damage mechanisms.