Etching-Free Dual Lift-Off for Direct Patterning of Epitaxial Oxide Thin Films

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 La_0.67Sr_0.33MnO₃ 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.