Nano-patterning on the order of sub-10 nm is integral to achieve high-density nano-scale devices for various data storage and data processing applications. However, the additional requirement of planarization and unwanted side-effects of physical or chemical etching have so far limited the patterning of sub-10 nm devices. In this work, we have demonstrated the creation of an array of ∼10 nm ferromagnetic islands through selective phase transformation of paramagnetic multilayers by low-energy proton irradiation. Paramagnetic Co3O4/Pd multilayers masked with patterned PMMA (polymethyl methacrylate) were reduced to ferromagnetic Co/Pd by proton irradiation. A clear contrast of the nano-islands was observed using magnetic force microscopy, establishing the formation of ferromagnetic nano-islands with perpendicular magnetic anisotropy. This process provides a way to circumvent the side-effects associated with both conventional nano-scale pattering and high-energy ion irradiation. Therefore, phase transformation by low energy proton irradiation can be used for patterning sub-10 nm nano-islands, not only for magnetic data storage but also for patterning various opto-electronic and spintronic devices.
Bibliographical noteFunding Information:
This work was partially supported by the National Research Foundation (NRF) Singapore (R-263-000-C26-281). Research at Yonsei University was supported in part by the Future Semiconductor Device Technology Development Program (10044723) funded by Ministry of Trade, Industry and Energy (MOTIE) and Korea Semiconductor Research Consortium (KSRC), by Creative Materials Discovery Program (2015M3D1A1070465) and by Grant (2014R1A2A1A11050290) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning, and by the Yonsei University Research Fund (Post Doc. Researcher Supporting Program) of 2016 (Project No.: 2016-12-023). This work was also partially supported by the A*STAR Nanoimprint Foundry (Project No. 1525300037). A. Oral acknowledges partial support from Middle East Technical University, Project No.: BAP-01-05-2017-008 and NanoMagnetics Instruments Ltd. P. Yang was supported from SSLS via NUS Core Support C-380-003-003-001. The authors would also like to acknowledge the Singapore Synchrotron Light Source (SSLS) for providing the facility necessary for conducting the research. The Laboratory is a National Research Infrastructure under the National Research Foundation Singapore.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)