Etching-Free Dual Lift-Off for Direct Patterning of Epitaxial Oxide Thin Films
Jiayi Qin, Josephine Si Yu See, Yanran Liu, Xueyan Wang, Wenhai Zhao, Yang He, Jianbo Ding, Yilin Wu, Shanhu Wang, Huiping Han, Afzal Khan, Shuya Liu, Sheng’an Yang, Hui Zhang, Jiangnan Li, Qingming Chen, Jiyang Xie, Ji Ma, Wanbiao Hu, Jianhong Yi, Liang Wu*, X. Renshaw Wang*
Nano Lett. 2025, 25, 35, 13184–13190
https://doi.org/10.1021/acs.nanolett.5c02947
外延单晶氧化物薄膜具有丰富的功能特性，但其实际应用仍受限于精准图案化难题。传统的图案化方法主要依赖于刻蚀工艺，该工艺成本高昂，且存在诸多问题，例如薄膜或衬底损伤、刻蚀不足、过度刻蚀以及横向刻蚀等。为此，合作团队提出了一种二次剥离法，用于外延单晶氧化物薄膜的直接图案化，从而有效规避了刻蚀工艺及其伴随的诸多问题。该方法主要包含以下两个步骤：首先，通过一次剥离光刻胶层来实现水溶性氧化物（非晶态Sr3Al2O6或Sr4Al2O7）的图案化；随后，在水中二次剥离水溶性氧化物得到图案化外延单晶氧化物薄膜。水溶性氧化物相比于传统高分子基光刻胶，可以在高温下保持稳定，起到类似“耐高温光刻胶”的作用，使其能够兼容外延单晶氧化物生长所需的高温条件。利用此方法，团队成功制备了高精度高质量的图案化La0.67Sr0.33MnO3和BiFeO3薄膜，所得薄膜图案与光刻胶图案保持了高度一致性。相较于传统刻蚀工艺，本研究提出的二次剥离法具有工艺流程简洁、操作灵活便捷、图案精度高、环境友好以及成本低廉等显著优势。
Abstract: Although monocrystalline oxide films offer broad functional capabilities, their practical use is hampered by challenges in patterning. Traditional patterning relies on etching, which can be costly and prone to issues like film or substrate damage, underetching, overetching, and lateral etching. In this study, we introduce a dual lift-off method for direct patterning of oxide films, circumventing the etching process and associated issues. Our method involves an initial lift-off of amorphous Sr3Al2O6 or Sr4Al2O7 (aSAO) through stripping the photoresist, followed by a subsequent lift-off of the functional oxide thin films by dissolving the aSAO layer. aSAO functions as a “high-temperature photoresist”, making it compatible with the high-temperature growth of monocrystalline oxides. Using this method, patterned ferromagnetic La0.67Sr0.33MnO3 and ferroelectric BiFeO3 were fabricated, accurately mirroring the shape of the photoresist. Our study presents a straightforward, flexible, precise, environmentally friendly, and cost-effective method for patterning high-quality oxide thin films.
论文被选为内封面（Supplementary Cover）。本论文得到了昆明理工大学易健宏校长，云南大学胡万彪教授等合作者的大力支持，在此一并表示诚挚感谢！