Magnetically shielded room - Ebeam applications
With today’s electron microscopes and experimental tools, researchers are analyzing structures on the atomic scale. However, deflections of the electron beam during an experiment may deteriorate the complete result. With Systron LabShield®, entire rooms are protected against magnetic fields. Systron LabShield® provides a flexible concept which can be readily adopted to the local situation and to the technical requirements, like doors and wall breakthroughs or mechanical damping. Often, active field cancellation systems are added, supporting the room shield.
Systron LabShield® is based on mu-metal in it's highest quality. However, for some applications, silicon-iron or even pure iron is used in addition, or instead, too, often combined with aluminum. Systron LabShield® is even suitable for clean room applications such as found in semiconductor manufacturing environment. Magnetically shielded rooms protect from magnetic sources such as transformers, switch gear, distribution panels, cables, overhead lines, tramways, railways, elevators, NMR, magnets.
In the Binnig und Rohrer Nanotechnologiezentrum, Rueschlikon, Zürich, so called "Noise-free" labs were built to host extremely sensitive equipment such as electron microscopes, litography and experimental tools. To ensure to get best results with the tools, the labs had to be protected from electromagnetic and magnetic stray fields. The specs demanded <5nT for fields of 16.7Hz railway and 50Hz mains frequencies. In order to meet the very challanging requriments, the rooms were lined with passive shielding method based on the proven Systron LabShield®, a magnetic shielding system based on mu-metal and aluminium.
Passive magnetic shielding
The magnetic shielding was designed in close cooperation between IBM and Systron EMV GmbH to ensure compatibility with all the various requirements such as climate control, vibration isolation and accoustics. As a result the rooms were entirely shielded with mumetal and aluminum plates. For maximum performance the aluminum plates have been welded to form the best possible electrical conductivity of the whole surface.
With the combined use of the materials, a very low magnetic field level was achieved. In addition, some labs were even supplemented with active cancellation systems. Third party measurements confirmed magnetic field levels as low as <2nT.