Etching resistance and particle suppression behavior of Y₂O₃–ZrO₂ composite coatings in fluorine-based plasma

Yttrium oxide (Y₂O₃) coatings serve as essential barrier layers for protecting chamber surfaces from plasma-induced erosion and contamination during dry etching in semiconductor and display fabrication. With increasing device complexity and elevated plasma power conditions, the demand for enhanced coating performance has intensified to support stable processing and high production yields. Accordingly, there is growing interest in coating systems that can sustain harsh plasma etching while maintaining a clean processing environment. In this study, Y₂O₃–ZrO₂ composite coatings (hereafter referred to as YZ coatings) were fabricated via atmospheric plasma spraying (APS), and their durability was evaluated through a 10-hour plasma etching process conducted in an 8.6-generation industrial ICP system operated with a CF₄/O₂/Ar gas mixture. Key durability metrics— maximum etch depth, mass change, reaction layer degradation, and ion elution—were quantitatively assessed. To evaluate dissolved ion release after plasma etching, Y ion concentrations (measured by ICP-OES) and Zr ion concentrations (measured by ICP-MS) in the ultrasonic cleaning solution were analyzed for high-sensitivity detection. The Y₂O₃–ZrO₂ composite coatings (hereafter referred to as YZ coatings) exhibited a 13% shallower maximum etch depth (4306.9 nm) compared to conventional Y₂O₃ (4946.96 nm), along with a reduction in total ionic elution by approximately 19% (from 2.13 mg/kg to 1.73 mg/kg). These improvements are attributed to the dual stabilizing effects of Zr addition, namely mechanical reinforcement of the microstructure and chemical stabilization via preferential Zr–F bonding, which suppresses excessive Y–F formation. XPS analysis confirmed that Zr⁴⁺ incorporation modified the surface chemistry by forming stable Zr–F bonds, which suppressed excessive Y–F bond formation and reduced fluorine incorporation. This effect can be explained by the smaller ionic radius (0.84 Å vs. 1.02 Å) and higher electronegativity (1.33 vs. 1.22) of Zr⁴⁺ compared to Y³⁺, which enhance its affinity for F⁻ ions and promote selective fluorination, thereby stabilizing the reaction layer. The smaller ionic radius of Zr⁴⁺ leads to shorter Zr–F bond lengths, resulting in stronger bonding and enhanced near-surface mechanical integrity. In addition, the higher electronegativity of Zr⁴⁺ favors stronger ionic–covalent interactions with fluorine, reducing the volatility of fluoride species and improving chemical stability at the surface. As a result, the YZ composite coating effectively suppresses plasma-induced material degradation and ion release, contributing to improved process stability and reduced chamber contamination under prolonged fluorine-based plasma etching conditions. These findings highlight the industrial significance of Zr-modified Y₂O₃ coatings for advanced semiconductor and display manufacturing environments.