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Materials science and
technology is fundamental to the majority of the applications of
nanotechnology. 'Raw' materials such as semiconductors, oxides
and specialist organic and inorganic chemicals, will need to
meet new specifications and parameters. For example:
Nanoparticles:
Controlled production of particles in the 1 - 100 nm size range
is crucial, and handling of these fine particles will be a key
issue.
Quantum structures:
Material purity is of the highest importance here, and research
into production methodology is required.
Multilayer thin films:
These require clean deposition equipment and environment
(impurities and defects will ruin the properties of the films)
with fast turn-around and high throughput... Also, very high
purity materials will be needed for sputtering and evaporation
sources.
Nanomechanical
devices: The
physical integrity of the material used to produce the devices
will be of key importance, given the strains and stresses to
which it will be subject.
Nanoprobe materials:
These are the materials required for the manufacture of tips for
scanning probe microscopes, the basic tools of nanotechnology.
These need to be chemically inert, physically stable materials
capable of being fashioned reproducibly into atomic sharp tips.
Biosensors and
transducers:
The capability of synthesizing ultra high purity specialist
organic chemicals having a range of terminating groups for these
applications is required, as well as ways of bonding these
molecules reproducibly to the surfaces of semiconductors and
oxide materials
Advanced
manufacturing processes:
Manufacturing processes at
the nanoscale can involve accretion or removal of material, or
changes to the shape or form of material already present. Each
of these processes provides new challenges and opportunities, as
follows:
Accretion of powders:
New generations of processing equipment will be needed to deal
with nanopowders in the manufacture of nanocrystalline
materials.
Quantum structures
and devices:
The problem of producing devices with critical dimensions below
100nm, using 'top-down' techniques, is one that the electronics
industry is currently wrestling with. Currently, commercial
lithography is based on optical methods,
10
Current
and Emerging Electronic And Computer Technologies
but the wavelengths of
visible and near ultraviolet light are too long to be usable on
the nanometer scale. A range of alternatives is available, but
parallel rather than serial writing techniques are needed for
scale-up to commercial manufacturing levels.
Deposition:
Recent breakthroughs are making deposition on selected areas
possible, in high transmission mode. Until now, this has been
achieved only through focused ion beam sources operated in
droplet mode - an approach which is restrictive in terms of the
range of materials that can be handled.
Cutting, milling:
Only focused ion beam (FIB) techniques provide a means for
selective cutting or removal of material with sub-100nm
accuracy. Although these techniques were largely pioneered in
Europe - and the UK in particular - the present suppliers of
such equipment are almost exclusively American or Japanese
companies.
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