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Completely Unified System
With a Strong Leading Role
In laser diode manufacturing, MOCVD*
crystal growth is said to be the first, and
largest, difficulty. Sony Shiroishi Semiconductor
is a manufacturing site that is unique
in the world, even if we only consider its
unified production system, which includes all
four manufacturing processes from MOCVD,
to the following wafer, assembly, and testing
processes.
However, this site’s uniqueness does not stop
there: Sony moved its blue-violet laser
development group here from the Research
Center in Yokohama in 1999. By being entrusted
with the development and design of
the blue-violet laser for the next generation
of large-capacity optical discs, Sony Shiroishi Semiconductor became a critical site that
holds the fate of optical media in its hands.
Sony Shiroishi Semiconductor’s president,
Isao Umezawa, describes the merits of the
fully integrated manufacturing system as
follows.
“Even if one understands that mass production
can be performed under the given
conditions in a development line, when one
switches to a mass production line at a manufacturing
site, things do not proceed
smoothly. The scale of operations and the
actual equipment used are different, and the
conditions end up being different. While this
is the same for all silicon semiconductors,
lasers are a particularly difficult device. For
that reason alone, it is important to be able to
apply exactly the same conditions as used in
development to mass production.”
Plainly stated, the main difference between
lasers and other semiconductor devices is
“the reversal of the leading role to the epitaxial
stage.” “While the equipment used for
growing crystals is called “epi(taxial)”, the
conditions in these epitaxial growth furnaces
differ slightly between each other. This is
because the growth must be controlled on a
nanometer scale. In silicon semiconductor
devices, the epitaxial process is truly our
hidden strength, and the processes that form circuits based on that foundation are the main
area of concern. However, lasers are exactly
the opposite: the epitaxial process is the star.
This is because the quality of the laser diode
product is changed greatly by how well the
crystal growth can be controlled. It is safe to
say that 80% of the competition with other
companies in this area is determined here.”
Managing director Masao Hanai describes
the essence of the epitaxial furnaces as follows.
“Subtle differences in the behavior within the
furnace, for example the amount of gas flow
or direction of flow, can cause problems.
Therefore the technology and know-how accumulated
up to now is our great strength in
the control of crystal growth.” This is a sturdy
technological foundation for this greatest of
technological problems, crystal growth. To
take advantage of this, we have created a
route consisting of a unified system from research
and development through manufacturing,
and are progressing toward mass production
of blue-violet laser diodes one step
at a time.
Keeping the Center of the World in
Sight while Spreading Our Wings in
the Tohoku Region
President Umezawa has said that he “wants
to make (Sony Shiroishi Semiconductor) the
‘center of the world’ for laser diodes.”
“Ten or fifteen years ago, Sony Shiroishi
Semiconductor was a site that only performed
assembly operations. This site has a tradition
of managers who have been committed to
making it a unified system. The previous
manager, who was fond of Mah-Jong, used
to say “ikki tsuukan da!” (a pun on “unified”
and a situation in Mah-Jong). Due to this commitment,
various processes were moved here
over the years. (See the chronology table.)
Since the result of this process has been to
create the current system, which is rare in the
semiconductor industry, I hope to push this
process even further and make this site the
‘center of the world’ for laser diodes. If you
go to Shiroishi, you can learn anything and
everything about lasers. We are always racing
at the leading edge. That’s the sort of site
I hope to create here.”
Managing director Hanai then emphasized his
feelings for the region.
“Although the shift to foreign production is
accelerating in the manufacturing industries,
I want to keep not only the wafer processes, but the assembly processes as well, here in
Shiroishi. We are continually striving for
revolutions in production, yield, and facilities.
For example, in the facilities area, about
90% of the epitaxial furnaces and high-precision
mounting stations in the assembly system
are internally manufactured equipment
that we designed ourselves. I hope to be able
to take even better advantage of such technologies
and also to contribute to stable employment
in the local community.”
Managing director Hanai recognizes persistence
and single-mindedness as a common,
regional personality trait among the locally
hired employees, who make up 70 to 80 %
of the work force.
“Our employees do excellent work, even in
the face of difficult problems. While our employees
do not have the effusive and showy
personality of the dahlia, their diligent efforts
pay off.”
A Name Brought by a Swan
Sony Shiroishi Semiconductor, which aims
at being the center of the laser diode world,
is also committed to achieving the industry’s
highest level of safety management and
environmental protection.
“Since, among other things, we also handle
special gasses, our investment in safety management
is in no way inferior to our investment
in manufacturing equipment. In the
corresponding areas of the plant, we have
installed 30 or 40 special gas leakage sensors.
Until now, we have had no accidents
that have required shutting down operations,
and our record for operation without an
accident exceeded 4800 days in May. It goes
without saying that our employees’ awareness
of safety issues is extremely high, and I
have confidence in the quality of our daily
improvement and maintenance activities.”
(Managing director Hanai)
When the northern Miyagi Prefecture earthquake
of 2003 occurred, the Shiroishi region
experience tremors that registered level 4 on
the Japanese earthquake intensity scale. Although
there was no direct damage from this
earthquake, the seismic sensors responded,
the flow of special gasses was cut off completely,
and the manufacturing lines were
stopped temporarily. This allowed us to verify
the effectiveness of our safety management
system.
Thoroughgoing environment activities are
being implemented. The special gasses used
are, of course, detoxified, we have introduced
the industry’s first gallium arsenide (GaAs)
detoxification equipment, materials used are
recycled, and even in the plantings in the
sites, no herbicides whatsoever are used. Actually,
when describing the environmental activities
at Sony Shiroishi Semiconductor,
there is a key word that is always used. That
word is “swan.” Every year in November,
over 200 swans fly in from Siberia and spend
the winter on the Shiroishi River that flows
by the site. It would be unacceptable for the
swans, who are treasured by the local community,
to the extent that there is even a
Shinto “Swan Shrine”, to stop coming. This
shared feeling of the employees increases our
enthusiasm for environmental activities, and
we even monitor the pH of the rainwater that
flows from the site into the Shiroishi River.
(Although it has never happened, the flow
would be cut off if an abnormal value were
measured.)
According to Managing director Hanai, “When the swans are here, all our employees
take turns feeding them.” This continues
without break, on weekends and even on New
Year’s Day. “The swans will come right up
to you at feeding time. They’re really adorable.”
said President Umezawa.
While there has not been a case of “The
Swan’s Gratitude” (a reference to a Japanese folk tale called “The Stork’s Gratitude”),
there have been unexpected blessings.
“While the environment here is truly wonderful,
the name of this town used to be a
name that implied the town was smaller and
more isolated than it actually was. Since Sony
feeds the swans and contributes scraps of rice
as feed to the “Shiroishi River Swan Society”,
the city council proposed changing the
name of the town to ‘Shiratori’ (‘Swan Town’
in English).” said President Umezawa.
Managing director Hanai added “It’s definitely
a warmhearted and respected name for
a locality.”
It is from this sort of region that the blue-violet
laser, which will support the arrival of
the full-scale digital broadcast age as its foundation,
and which will support the next generation
of large-capacity optical discs, will
soon be mass produced and shipped to the
world. |
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Vol.41
