(562b) Solvent-Free Bottom-up Patterning of Zeolitic Imidazolate Frameworks

There is long-standing attention to developing a patterning process for porous materials, including metal-organic frameworks (MOFs), considering their potential use in electronic and optical devices.^[1]

Recently, significant progress on a fundamental understanding of amorphization of MOFs and zeolitic imidazolate frameworks (ZIFs), a subclass of MOFs induced by X-ray^[2] and electron beam (e-beam) irradiations,^[3,4] has been made. Furthermore, a clear solubility switch was observed for a particular type of ZIFs with halogen atoms on the structural linkers by the irradiations, facilitating selective removal of the exposed or non-exposed regions in a liquid-phase developing step, thereby realizing ZIF patterns.^[5]

This presentation includes our recently completed work on an e-beam assisted, solvent-free, bottom-up approach to patterning non-halogenated ZIFs.^[6] A mild pretreatment of metal oxide precursors (i.e., ZnO for ZIF-8 and CoO_x for ZIF-67) with 2-methylimidazole (2mIm) linker vapor enables the sensitization of the oxide surface to e-beam exposure, effectively delaying the subsequent conversion of the oxides to ZIFs in irradiated areas. In contrast, ZIF growth in non-irradiated areas is not inhibited. As a result, well-resolved patterns with features down to 100 nm are accomplished. This developer-free, all-vapor phase technique holds a promise for incorporating MOFs in micro and nanofabrication processes.

Our key strategy to allow for solvent-free and maskless ZIF patterning will be highlighted throughout the presentation. A systematic investigation will also be discussed on the 2mIm-sensitized oxide film through various characterization methods, including atomic force microscopy, transmission electron microscopy, grazing incidence X-ray diffraction, and X-ray photoelectron spectroscopy.

References

[1] I. Stassen, N. Burtch, A. Talin, P. Falcaro, M. Allendorf, R. Ameloot, Chem. Soc. Rev. 2017, 46, 3185.

[2] R. N. Widmer, G. I. Lampronti, N. Casati, S. Farsang, T. D. Bennett, S. A. T. Redfern, Phys. Chem. Chem. Phys. 2019, 21, 12389.

[3] S. Conrad, P. Kumar, F. Xue, L. Ren, S. Henning, C. Xiao, K. A. Mkhoyan, M. Tsapatsis, Angew. Chemie Int. Ed. 2018, 57, 13592.

[4] Y. Miao, M. Tsapatsis, Chem. Mater. 2021, 33, 754.

[5] M. Tu, B. Xia, D. E. Kravchenko, M. L. Tietze, A. J. Cruz, I. Stassen, T. Hauffman, J. Teyssandier, S. De Feyter, Z. Wang, R. A. Fischer, B. Marmiroli, H. Amenitsch, A. Torvisco, M. de J. Velásquez-Hernández, P. Falcaro, R. Ameloot, Nat. Mater. 2021, 20, 93.

[6] Y. Miao, D. T. Lee, M. D. de Mello, M. Ahmad, M. K. Abdel-Rahman, P. M. Eckhert, J. A. Boscoboinik, D. H. Fairbrother, M. Tsapatsis, Nat. Commun. 2022, 13, 420.