An overview of electron beam lithography
Electron beam lithography uses a focused electron beam to pattern the surface of a material. As electron beams can be very tightly focused and small beam sizes achieved, electron beam lithography can be used to create very intricate structures for a wide variety of nanofabrication applications.1
What is the electron beam lithography process?
The electron beam lithography process involves covering the surface of the substrate with a resist. Certain areas of the sample are then exposed to the incident beam of electrons that allow for the pattern's direct writing into the resist layer.
The sample is exposed by the electron beam in very fine steps to create the pattern. At each step, the resist must be exposed for sufficient time for the beam to activate the resist. Determining the optimal time for this in electron beam lithography is one of the steps in the process automation of the technique.
Once the resist layer has been exposed, the remaining resist is developed through chemical treatment of the sample, often with solvents such as acetone or alcohols that will dissolve the resist layers. Polymers such as PMMA (positive tone) and HSQ (negative tone) are popular choices for electron beam lithography resists and can be spun in very thin layers on top of the substrate of choice for the electron beam lithography process.
What is electron beam lithography used for?
Nanofabrication is one of the biggest applications for high-resolution direct-write methods like electron beam lithography.2 Many technologies, from new metalens structures toquantum computing, rely on techniques such as electron beam lithography to create the complex surface structures that these applications demand. One of the biggest challenges to be overcome with many new nanotechnology developments is reliable fabrication techniques for creating devices, and electron beam lithography is one potential solution for that.
Other applications of electron beam lithography include creating complex structures such as metal-organic frameworks (MOFs) that are now of interest for the miniaturization of solid-state devices.3 There are industrial applications using EBL for production of communication devices, due to the beam position’s nanometer-level accuracy and small linewidth capabilities.
What is the advantage of e-beam lithography over photolithography?
Photolithography involves the use of optical beams. As the diffraction limit of visible light is on the order of hundreds of nanometers, this limits the spatial resolution achievable with photolithography. While electron beam lithography is also diffraction limited, the diffraction limit of the high energy electrons that can be produced in various electron beam lithography experiments is on the order of nanometers or even sub-nanometer.
The improved spatial resolution of electron beam lithography means much more detailed, and complex structures can be created than with photolithography methods, though the latter has the advantage of higher throughput.
JEOL Solutions
JEOL are world leaders in electron beam technologies and has a number of products available to support
electron beam lithography processes. Contact JEOL today to see how your direct-write processes could benefit from JEOL’s expertise in the development and optimization of electron beam lithography experiments.
References
- Nagashima, K., Zheng, J., Parmiter, D., & Patri, A. K. (2011). Biological Tissue and Cell Culture Specimen Preparation for TEM Nanoparticle Characterization. In S. E. McNeil (Ed.), Characterization of Nanoparticles Intended for Drug Delivery (pp. 83–91). Humana Press. https://doi.org/10.1007/978-1-60327-198-1_8
- Chen, Y. (2015). Nanofabrication by electron beam lithography and its applications : A review. Microelectronic Engineering, 135, 57–72. https://doi.org/10.1016/j.mee.2015.02.042
- Tu, M., Xia, B., Kravchenko, D. E., Tietze, M. L., Cruz, A. J., Stassen, I., Hauffman, T., Teyssandier, J., Feyter, S. De, Wang, Z., Fischer, R. A., Marmiroli, B., Amenitsch, H., Torvisco, A., Velásquez-hernández, M. D. J., Falcaro, P., & Ameloot, R. (2021). Direct X-ray and electron-beam lithography of halogenated zeolitic imidazolate frameworks. Nature Materials, 20, https://doi.org/10.1038/s41563-020-00827-x
- Smith, D. J. (2008). Ultimate resolution in the electron microscope? Materials Today, 11, 30–38. https://doi.org/10.1016/S1369-7021(09)70005-7
- JEOL (2022) Scanning Electron Microscopes, https://www.jeolusa.com/PRODUCTS/Scanning-Electron-Microscopes-SEM, accessed April 2022
- Arenal, F. L., A., D., & R., M. (2015). Advanced transmission electron microscopy. Springer