Research on inductively coupled plasma etching characteristics of large-area TiO2 gratings based on nanoimprinting

This paper addresses the issues of low etching selectivity caused by high density and difficult uniformity control in largearea TiO₂ grating fabrication. Innovatively, nanoimprint technology is combined with inductively coupled plasma (ICP) secondary etching process. A Cr layer is deposited by magnetron sputtering, and high-efficiency fabrication of a large-area two-dimensional TiO₂ grating with an effective diameter of 75 mm is achieved through secondary hard mask etching. In the first etching stage, Cl₂ and O₂ are used to etch the Cr layer with the imprinted photoresist as a mask, forming a Cr mask layer with high etching selectivity. In the secondary etching stage, Cr is used as the mask layer to etch the atomic layer deposited TiO₂ layer. By optimizing the mixing ratio of CF₄/CHF₃/Ar/O₂ and power parameters, high-quality nanohole array structures of TiO₂ are obtained. This study confirms that the synergistic effect of nanoimprinting and ICP secondary etching can break through the chemical inertness limitation of TiO₂, laying a process foundation for large-scale manufacturing of subwavelength TiO₂ gratings. It provides a referable preparation approach for the application of TiO₂ nanostructures in optoelectronic conversion, catalytic reactions, biosensing, and other fields.