Invention: Extreme ultraviolet lithography for smaller, more powerful microchips
The next generation of microprocessors is being produced with European hi-tech thanks to key inventions in extreme ultraviolet lithography (EUVL) manufacturing by Dutch engineer Erik Loopstra and Dutch-Russian physicist Vadim Banine. Patented and brought to market by chip equipment manufacturer ASML, their technology uses high-energy lasers to achieve nanoscale details, thereby producing smaller, faster and more powerful semiconductors.
The computing power of microchips, measured in the density
of transistors packed onto a single chip, has doubled every two years since the
1960s. While chips once contained thousands of transistors, now billions fit
onto them. This evolution fulfils Moore's law, formulated by Intel Corporation co-founder
Gordon Moore.
But, in recent years, the microchip industry has been approaching
a plateau. The wavelength of laser light that is used to etch detailed
transistor patterns onto silicon chips has been reaching its physical limit - portending
an end to Moore's law.
Enter Banine and Loopstra at lithography systems company
ASML. Over the course of 20 years, the two used their skills as physicist
and system architect respectively to break the wavelength barrier. Their
patented inventions in EUVL reduce radiation wavelength by a factor of 14 to
only 13.5 nanometres, well below the one-time "wall" of 193 nanometres. Global microchip manufacturers are now
adopting ASML's EUVL technology for large-scale production.
Societal benefit
Smaller and more powerful microchips are the key to new
applications in fields such as communications, healthcare and transportation. EUVL
will be the enabling technology behind next-generation chips that feature
details at a scale of seven and five nanometres.
To put that into perspective, five nanometres is twice the thickness of a
strand of DNA; a human hair is 20 000 times thicker than five nanometres.
Besides next-generation smartphones and tablet computers, this
computing power will support smaller and more powerful medical implants,
wearable electronics and "lab-on-a-chip" devices.
ASML's advanced EUVL platform has helped to strengthen
Europe's technology foothold. The region surrounding the Dutch city of
Eindhoven, where ASML is based, is known as the Brainport region. In 2011, the
Intelligent Community Forum named it the "smartest region in the
world" for creating synergies between enterprises and think tanks,
including the Eindhoven University of Technology (TU/e).
Economic benefit
Patent holder ASML now offers the team's inventions in a
complete product. Four of the world's largest
semiconductor companies - Samsung, TSMC, Intel and GLOBALFOUNDRIES - will adopt
ASML's EUVL platform in the next two years.
ASML is already the world's largest lithography systems
company, with an estimated share of market revenue of over 85% in 2018. Founded
in 1984, the publicly traded company employed 19 200 people worldwide and
reported sales of EUR 9 billion and profits of over EUR 2 billion
in 2017.
Fuelled by insatiable demand for microchips, the global
semiconductor industry is booming. In 2017, worldwide sales topped EUR 334 billion,
exceeding a 20% year-on-year growth rate, as reported by the Semiconductor
Industry Association. Analysts at MarketsandMarkets expect the photolithography
equipment market to reach EUR 6.5 billion by 2020, with the highest
growth in EUVL equipment.
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Vadim Banine (left) and Erik Loopstra
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Vadim Banine
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Erik Loopstra
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Erik Loopstra (left) and Vadim Banine
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Vadim Banine (left) and Erik Loopstra
How it works
Microchips are created by "photolithography", a
production method using lasers to etch miniscule
patterns for transistors and switches onto silicon wafers. But the level of
detail and ease of manufacturing are limited by current ultraviolet lithography,
which requires extra manufacturing steps - masking and special lenses - to produce chip features at scales below 45 nanometres.
Banine, Loopstra and their team developed an EUVL process to
deliver a much shorter radiation wavelength that almost falls within the X-ray spectrum.
Instead of using direct laser light to etch the silicon, EUVL aims a
high-powered laser at tiny droplets of tin. Exposed to the laser's heat, the
metal droplets melt into gleaming plasma and emit radiation in the "extreme
ultraviolet" spectrum at a wavelength of only 13.5 nanometres. This
wavelength is perfect for etching ultra-delicate structures onto silicon.
To do this, the inventors directed the radiation via
reflectors - ultra-smooth mirrors with flawless surfaces - for which their German
partner, optical manufacturer ZEISS, invented an entirely new material. And because extreme ultraviolet light can be
absorbed even by air, the team had to design a vacuum environment to do so. They
also had to reduce contamination - caused by lumps of material 1 000 times
thinner than human hair - to almost zero. Just one dust particle could render
a microchip useless.
In production lines, the patented technology will not be
used to create entire chips, but only for the most detailed and precise layers.
These layers will then be assembled onto finished semiconductors with so-called
"exposure layers", about 100 per chip, created with other types
of lithography.
The inventors
Since joining ASML in 1991, Erik Loopstra has played a key
role in bringing EUVL solutions to market in a process that has involved over 1 000
in-house experts. "Innovation is one per cent inspiration and ninety-nine
per cent perspiration," he says, quoting Thomas Edison. "Nobody would
invest so much time and money without being sure that it could be worthwhile at
the end."
As his innovative ambitions grew, so did his department. When
the native of Lillestrøm,
Norway, started working at ASML over 25 years ago, the development team consisted
of only 100 people. Today, this branch has grown to 2 000 employees, with
Loopstra also working on next-generation EUV optical systems at ASML's supplier
ZEISS in Germany.
Loopstra's work has yielded 65 granted European patents,
as well as the Dutch Society for Precision Engineering Martin van den Brink
Award in 2012. In his free time, the inventor takes breaks from high-powered
lasers by retreating to his workshop, where he crafts wood furniture.
Vadim Banine is a native of Moscow, Russia, where he earned
a degree in physics from the Moscow Institute of Physics and Technology in
1988. He joined ASML in 1996 after spending two years as a postdoctoral
researcher at the Laboratory of Heat and Mass Transfer at TU/e, where he also
earned his PhD. He has since contributed scientific insights behind the
breakthroughs in EUVL technology.
Today, he is
equally at home in the world of research and enterprise. He became ASML's Director
of Research in 2010 and was appointed Professor for Physics and Technology of
EUV Lithography at the TU/e Department of Applied Physics in 2013. Banine is named on 45 granted European patents
and has authored over 50 scientific publications.
"Patents freed me. They guaranteed that I could focus
100% on my work, not being worried about anything else. That's really great,"
says Banine. He now participates in ASML's co‑operation with a wide range of
industrial and research parties to test the optical elements and plasma system
at the EUVL system's core.
Did you know?
Patented microprocessor innovations have done well at
the European Inventor Award since day one. Loopstra and Banine are the latest in
a series of finalists and winners that started at the very first European Inventor
Award in 2006, when the legendary 4004 microchip earned its inventor Federico Faggin the Lifetime achievement
award. That same year, top honours also went to DNA-analysis microchips from Stephen P.A. Fodor
and team, who won the award in the "Small and medium-sized enterprises"
category.
In 2015, Swiss analytic chemist and nanoscientist Andreas Manz received the
Lifetime achievement award for shrinking a chemistry laboratory down to fit on a
microchip-sized wafer. One year before, a microprocessor-equipped USB stick
that decodes a patient's DNA within minutes earned British scientist Christofer Toumazou the award in the
"Research" category.
Other finalists
who pushed the boundaries in microprocessor design include UK engineer Sophie Wilson with her ultra-efficient
ARM processors for mobile devices (2013, "Lifetime achievement"
category). And in 2016, Portuguese inventors Elvira Fortunato
and Rodrigo Martins ranked among the finalists
in the "Research" category for developing paper-based microprocessors.
