Interview with Mikhail Erdmanis
Who are you?
Picture. The authors' team, from left to right: Nikolai Chekurov, Ali Shah, Victor Ovchinnikov, Mikhail Erdmanis, Päivi Sievilä and Professor Ilkka Tittonen.
My name is Mikhail Erdmanis. I am a researcher (PhD candidate) in the Micro and Quantum Systems Group (MQS) led by Professor Ilkka Tittonen. The group is a part of the Department of Micro- and Nanosciences (MNT) at Aalto University in Finland. My research topics include micro- and nanofabrication, photonics, and plasmonics. I am also responsible for the maintenance of the focused ion beam (FIB) Helios 600 dual beam system installed in Micronova, which is a large-scale clean-room facility for basic research and R&D purposes.
What prompted you to pursue this field of research?
When I became a main user of FIB, I realized that the equipment had great potential as a lithography tool, which was unfortunately deeply underestimated. At the same time, I saw a demand for nanostructures that are very challenging to fabricate by commonly used electron beam or ultraviolet lithographies. This was a starting point for the development of an alternative FIB lithography process. The developed method is very fast, and I was able to test new concepts and fabricate multiple prototypes within one day. The results obtained by FIB lithography exceeded our expectations in terms of structure quality and resolution on non-planar surfaces. I owe the success to our fantastic team, which has strong knowledge and expertise in nanofabrication and provided me with advisory and technical support.
What is this latest paper all about?
The article presents a nanofabrication method for patterning on corrugated and multilevel surfaces. It addresses the challenges that appear when resist deposition, exposure, and structure etching are performed on non-planar samples. In order to tolerate different height levels, we utilized atomic layer deposition (ALD) of ion-sensitive resist, exposure by FIB with a very large depth of focus, and optimized dry etching.
Due to the high quality of ALD films, we could also perform a structure release through the proper adjustment of dry etching parameters. In this paper, we demonstrated the fabrication of 50-nm-wide suspended nanobridges that follow the inclined wall of a micron-scale groove and retain their width from the top to the bottom. Such released nanostructures provide a platform for thermal conductivity measurements and various types of sensing, which can be integrated with micro- and nanofluidics, and lab-on-a-chip applications. The proposed method is fast and reproducible due to the minimized number of process steps and absence of wet etching.
What do you plan to do next?
We are considering a few options for future research that continue the presented study. One possibility is to investigate new combinations of ion-sensitive resist materials (e.g. ALD nanolaminates) and new types of structures. Another one is to use suspended nanostructures as a platform for consequent deposition of other materials and their implementation in measurement setups. We also consider the application of the process to polymers.