Strengthening Cu/Y₂O₃ Interfaces via Thermally Induced In Situ Growth of Root-like Anchoring Structures

In high-power semiconductor plasma etching equipment, copper components are indispensable for managing extreme cyclic thermal loads due to their exceptional thermal conductivity. To isolate copper components from the highly oxidative and corrosive environment, a protective yttrium oxide coating is deposited on the surface. Nevertheless, the long-term reliability of this bimaterial system is frequently compromised by the substantial thermal expansion mismatch between the ceramic coating and the metal substrate, which induces catastrophic interfacial delamination under cyclic thermal stress. To address this challenge, we propose an adaptive interface strategy that utilizes thermal stress to drive beneficial structural evolution, rather than passively suppressing it. Controlled thermal shock cycles trigger the stress-driven upward diffusion of copper ions, which react in situ to form a Cu₂O secondary phase. Notably, this phase preferentially wets the vertical grain boundaries of the columnar Y₂O₃ coating, resulting in a dense, bioinspired root-like 3D interlocking network. This crack-triggered architecture transforms microcracks from structural defects into diffusion-assisted reinforcing features that stabilize both coating integrity and interfacial adhesion under thermal shock. Consequently, after 50 thermal shock cycles, the coating exhibits significant toughening, with hardness increasing from 16.31 to 21.82 GPa, while retaining its original plasma etching resistance. This study establishes the theoretical framework for designing metal-ceramic integrated coatings through diffusion-controlled interface activation, providing fundamental insights into a robust engineering solution that significantly extends the service life of critical copper components in advanced plasma etching systems, thereby catering to the industrial demand for reliability under extreme thermo-mechanical loads.