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Ultra-bright nanoscale SEM-on-a-chip

Final Report Summary - MONARCH (Ultra-bright nanoscale SEM-on-a-chip)

The MONARCH project investigated a sub-miniature scanning electron microscope, a completely new concept in electron microscopy. The microscope is 5 µm long and has atomic resolution (2 A) at 500 eV energy and 10 nA of current. The low energy means it is capable of identifying single atoms on a surface as well as being able to make holograms of large molecules. Other capabilities include:
- its magnification is 1 µm and the focal length is 7 µm;
- aberrations contribute less than 0.2 A to the spot size.

The MONARCH project made significant progress towards the world's first Scanning electron microscope (SEM) on-a-chip. Such an instrument represents a step-change in electron beam (e-beam) technology comparable with the introduction of the silicon chip to electronics. This device is several orders of magnitude smaller than existing technology, operates at lower voltages and has an order of magnitude higher resolution for a fraction of the cost of a current state-of-the-art SEM. It provides the first instrument capable of rapidly scanning a surface layer and producing an image with elemental identification at atomic resolution.

This disruptive technology has dramatic implications for many sectors other than electron microscopy, including e-beam lithography, genetic sequencing, ultra-high density data storage and focussed ion beam milling. In particular, it is expected to be a key enabling tool for the booming sectors of nanotechnology and micro-nano-electromechanical systems (MNEMS). Crucially, it could also allow lithography on a scale suitable for true nanoelectronics.

The physics behind the MONARCH project are beautifully simple: by scaling the device dimensions down to the nano-scale, the voltages, beam energies and aberrations are scaled down proportionally. The system becomes diffraction-limited, rather than aberration-limited, and the lenses can be electrostatic rather than magnetic. These principles have been known for decades, but the realisation of such devices has only been made possible through very recent parallel advances in several nano-machining technologies: improved FIB techniques, the evolution of MEMS technology and scanning probe microscopy (e.g. very short focal length electrostatic lenses). In short, these techniques have transformed a thought experiment into a realistic possibility: ultra-low energy, ultra-high power, ultra-pure e-beams.

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