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
Published: 2025/9/1
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, under-etching, over-etching, 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 Sr$_3$Al$_2$O$_6$ or Sr$_4$Al$_2$O$_7$ ($a$SAO) through stripping the photoresist, followed by a subsequent lift-off of the functional oxide thin films by dissolving the $a$SAO layer. $a$SAO functions as a ``high-temperature photoresist", making it compatible with the high-temperature growth of monocrystalline oxides. Using this method, patterned ferromagnetic La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ and ferroelectric BiFeO$_3$ 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.