Cerium(IV) oxide addition to yttrium oxide thin films for enhanced etch resistance in fluorine-based plasma

초록

Dry etching processes in semiconductor manufacturing expose ceramic chamber components to aggressive fluorine-based plasmas, necessitating the development of durable protective coatings. Although yttrium oxide (Y2O3) is widely used as a protective coating in the semiconductor industry, it remains susceptible to surface fluorination and sputtering-induced erosion. In this study, CeO2-doped Y2O3 thin films were fabricated by electron-beam physical vapor deposition (EB-PVD). Structural analysis revealed a transition from the bixbyitetype Y2O3 lattice to a fluorite-type structure with increasing CeO2 content, exhibiting extended solid solubility beyond bulk phase diagram limits due to the non-equilibrium nature of EB-PVD. For CF4-based plasma etching, a minimum etch rate which was approximately 45% lower than that of undoped Y2O3 was obtained for the 0.2Ce sample. X-ray photoelectron spectroscopy and electron energy-loss spectroscopy (EELS) analyses indicate that at this composition, Ce is incorporated predominantly as Ce4+, reducing oxygen-vacancy-related defect concentrations and thereby suppressing fluorine incorporation. Post-etch EELS further revealed near-surface redox transformations (Ce4+-> Ce3+) consistent with charge compensation under fluorine plasma exposure. These findings demonstrate that oxygen vacancy engineering combined with the judicious selection of dopants to form low-sputtering-yield fluorides is an effective material design strategy for improving the plasma durability of oxide coatings in semiconductor processing environments.

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