Identifying and overcoming the source of magnetic field interference

6 January 2022

Electron beam lithography is commonly used to fabricate small devices used in computers, photonics and sensors. Since the technology relies on accurate positioning of the electron beam, it is very sensitive to interferences like vibrations and stray electromagnetic fields. Elliot Cheng, Electron Beam Lithography (EBL) Specialist and Roger Wepf, Director of the Centre for Microscopy and Microanalysis (CMM) describe how they solved this problem using a Spicer SC24 magnetic field cancelling system.

CMM is an electron microscopy facility involved in research and teaching, as well as providing consultancy services. The centre offers expertise in different electron microscopy technologies and has recently built a new clean room where computer, photonics and sensor devices are fabricated using EBL. However, the new facility immediately began to present real challenges to the researchers when they started seeing unexplained background noise showing up in their data. Elliot explained: ”The devices we’re making are extremely small and it is crucial that the electron beam is accurately positioned, something that is greatly affected by any magnetic interferences. Ideally, levels on this kind of application should not be higher than 0.5 milligauss, but we were seeing peaks located around 50 Hz that were significantly higher than that, which jeopardised the accuracy of the instrument.”

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