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Shoichiro
Yoshida
Corporate Advisor |
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Known as the most precise
machines in the world, steppers are key machines
in the creation of IC chips that have become
indispensable for cell phones, computers,
car navigators, TVs and almost anything else
electronic. These "mother machines" are what
enable us to manufacture integrated circuits.
Here, the engineer known as the father of
the stepper, Shoichiro Yoshida of Nikon, discusses
the development of this revolutionary technology.
Nikon
steppers have a leading share of the world
market, but what are they?
A stepper is a machine that forms the ultra-fine
circuit lines onto the silicon wafer from
which chips are made. To make the most advanced
chips, these machines are now required to
fabricate circuits at the level of just a
few nanometers*.
How
was the stepper developed?
When I joined Nikon in 1956, I became involved
in a project to develop a 36-inch reflector
telescope, at that time, the largest of its
kind in Japan. For eight years, I designed
telescopes and instruments. This equipment
is of necessity highly sensitive to light,
and also extremely precise in the measurement
of position. It was a fascinating field in
which to work.
At that time I was concerned about
the foundation of Japan's industrial technology.
Unlike in Europe, where industrial competence
was built up step-by-step by the centuries-old
presence of trade guilds, our industry had
developed rapidly, like a tower built on a
hill of sand. We depended on foreign imports
for most of our mother machines, as well.
I soon became involved in a project
to develop ruling engines, machines equipped
with diamond cutters to etch anywhere from
hundreds to thousands of single millimeter
grooves at precise intervals onto small glass
plates.
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NSR-S609B
Light source: ArF excimer laser
(Wavelength: 193 nm)
Resolution: less than 55 nm |
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And
that uncompromising dedication to technology
led you to the development of steppers?
Correct. To create the stepper, three key
Nikon technologies were integrated and advanced
to a new level.
The first, and the heart of the
stepper, is an ultra-high resolution optical
lens. This was made possible by Nikon's strength
in lens manufacturing and experience in the
development of microscope objective lenses.
Next is the ultra-high controlling technology
for transferring patterns to the wafers—that
evolved from ruling engines. Much painstaking
work resulted in the achievement of extreme
precision in X-Y (left-right, forward-backward)
stage control.
The third component of the stepper
is photoelectric sensing techniques that wed
traditional optical technology with electronics,
allowing for the automation of these devices.
The role of photoelectric sensors
is of particular note. In a series of meetings
on business directions for the “post-camera”
era that often extended to after hours, all-night
discussions (see box below), we debated the
development of automation systems for optical
machines. We agreed that ultra-high precision
robots incorporating photoelectric sensors
should be the goal. And, that led us to the
stepper.
May
we hear your thoughts on Japanese industry
today?
Besides developing their own advanced technologies,
companies must also go beyond the boundaries
of their respective fields, finding new partners
where mutual benefit can be gained. Among
Mitsubishi companies, more active communication
is also needed, and greater efforts should
be made to enhance each other's capabilities.
*One billionth of a
meter (10-9 meters). |
