Oxygen plasma-assisted magnetron sputtering deposition of non-stoichiometric Y2O3 films: Influence of oxygen vacancies on etching resistance

Abstract

Yttrium oxide (Y₂O₃) films are widely used to protect equipment in plasma etching, a crucial technique in semiconductor processing, due to their exceptional resistance to plasma etching. Since oxygen vacancy affects the performance of Y₂O₃ and may impact physical etching resistance, the internal relationship necessitates further investigation. In this article, Y₂O₃ films with varying oxygen vacancy concentrations are prepared by reactive magnetron sputtering with the assistance of oxygen plasma. The formation and development of oxygen vacancies in cubic Y₂O₃ films and their impact on the physical etching resistance were investigated. The experiment results indicate that the accumulation of oxygen vacancies causes non-stoichiometry and the etching rate is significantly reduced. Combined with density-functional theory, it is revealed that oxygen vacancy distorts the lattice, which increases covalent Y–O bonding and the formation energy of atoms. Moreover, the vacancy line defects resulting from diffusion and aggregation of oxygen vacancies exert a similar influence on the adjacent yttrium and oxygen layers. The enhancement of physical etching resistance is attributed to the strengthened internal Y–O bonds led by increasing oxygen vacancy concentration in the cubic Y₂O₃ films without inducing phase transition. The discovery enriches the understanding of how plasma interacts with Y₂O₃, and the etching mechanism.