A new nanotechnology tool that will dramatically cut the cost of leading-edge
nano research at the sub-50nm scale has been developed by EU researchers. It
could lead to Next Generation Lithography (NGL) technology.
The commercially available first generation tool is low cost compared to sub-50nm
alternatives. For example, electron beam lithography costs €2m per machine,
whereas the Soft Ultraviolet (UV) Imprint machine developed by SOUVENIR project
costs in its basic version well below €200,000. It will be used to produce
novel and experimental nanotech devices.
"In principle, this new technique has the potential to be used for mass manufacture
by the semiconductor industry. One approach we use can already form patterns
down to the 10nm scale," says Dr Markus Bender, researcher at German company,
Applied Micro- and Optoelectronics (AMO), and SOUVENIR coordinator.
Next Generation Lithography (NGL) is the holy grail of the semiconductor industry.
It will allow rapid, large-scale manufacture of modern microchips at a sub-50nm
scale. Industry giant Intel has spent 15 years and millions of dollars looking
for it. A small but brilliant team of dedicated researchers in Europe may have
found the solution.
Photolithography works by casting light through a mask to produce a pattern on
a chemically-coated substrate. The light changes the chemical structure of the
substrate. Depending on the type of photolithography, either the lit or shadowed
chemical is washed away in the next step. In either case the result is a pattern
etched into the substrate.
With nanolithography the patterns are invisible to the naked eye and the vast
majority of the world's microscopes. The result is the tiny circuits in semiconductor
The SOUVENIR project developed a new technique to create those patterns, one
that is low cost and, comparatively, low tech. In a first step the substrate
was coated with a low viscosity, UV-curable resist. The resist is simply a UV-sensitive
chemical layered onto the substrate. They then used a soft polymer mould, called
an elastomer, pressed against the resist-coated substrate, called imprinting,
followed by the UV photopolymerisation, or curing, of the resist.
This costs less than other photolithographic techniques. Because the mould is
pressed against the resist, the system does not require the extremely expensive
'deep' UV light sources used in the semiconductor industry. These light sources
can only work properly in a vacuum. Finally, the elastomer mould is considerably
cheaper than those used in microchip manufacture. The result is a low-cost pattern
process at the sub-50nm scale.
However, the low cost comes at a price. Currently, the system is too slow and
unproven to replace the current industrial photolithography processes. What's
more, the elastomer moulds used in the SOUVENIR process at the moment need further
improvements for high-resolution alignment processes, essential for mass manufacturing
But ultimately it has the potential to become the next generation lithography.
Thanks to research completed by the German government's Federal Ministry of Education
and Research (BMBF), it is possible to use the same imprinting technique using
a hard mould, based on quartz, which does have the required precision for semiconductor
manufacture. However, while quartz could address the precision issues the technique
is currently too slow for large-scale semiconductor companies.
"This is the first generation of the tool we developed and, with work, we can
in principle get much better, faster and more scalable results," says Dr Bender.
"We are working in close cooperation with an Austrian company, Electronic Vision
Group (EVG) to develop tools for the two approaches. I think next year we'll
have a step and repeat tool for 300mm wafers on the market," says Dr Bender.
This first generation tool is designed for small volume production, for example
for chemical sensors and in biotechnology applications at small companies and
research centres. Right now, small companies can't afford their own tools for
sub-50nm nanotech devices.
But ultimately, this research could change how the semiconductor industry works.
"This is a totally new technique and we've got to prove that we can reliably
reproduce the results. That's what we'll be doing now," says Dr Bender.
Dr Markus Bender