ETH-Zürich: Low-voltage field-emission scanning electron microscope

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Researchers at the ETH-Zürich, Switzerland, have have combined the fundamental concepts of two novel surface science techniques, scanning electron microscopy (SEM) and scanning tunneling microscopy (STM), to create a new device which they say minimises the trade-offs of both methods.

This microscope introduces a way of generating a primary beam of electrons without using an electron gun. Potentially, it will eliminate the need of an electron gun for thin film analysis on the sub-micron scale.

ETH transfer, the ETH’s technology transfer offic, says the SEM is both cost-efficient, and can image the topmost layers of surfaces with high spatial resolution – a lateral resolution of 1.2 nanometres at a step edge height of 0.2 nanometres. The instrument, it says, is quite compact and can easily be integrated with existing systems.

The microscope is capable of imaging conducting surfaces using beam energies of less than 60 electronvolts. Such low energy – well below the 200 electronvolts of next-generation high-resolution SEMs – reduces distortions even further.

Possible applications are in industrial resesrch for sub-micrometre surface analysis, for example of magnetic recording media, biosensors, semiconductors, surface coating technology or electron beam lithography, as well in academic research. Its low cost also enables it to be be used in student laboratory courses in microscopy and ultra-high vacuum systems.