Members' Profiles

Fuji Electric Systems Co., Ltd.
1. MEMS Projects at Fuji Electric Systems

3. Inkjet Heads

For more than 20 years, Fuji Electric Systems has
used MEMS technology to produce semiconductor
pressure sensors for industrial instrumentation and has
manufactured numerous MEMS devices during that time.
These projects are made distinctive through use of ourcore technologies in deep silicon etching and bonding.
We have also recently applied these core technologies
toward developing a MEMS foundry service at our Tokyo
plant in Hino. The plant is equipped with a clean roomapproximately 1,500 m2 in floor area that is being used forthe development, trial production, and mass production of
MEMS devices through integrated process steps fromphotolithography to film formation, etching, and bare chipmounting.

Since developing an inkjet recording head for image
recorders, Fuji Electric has continued to expand
applications for the recording head in commercial andindustrial equipment. In our Kaiser on-demand recording
head employing piezoelectric elements, ink channels areformed in the head by deep etching a silicon wafer andanodically bonding the wafer to glass. We have also
recently begun applying elemental technologies fromthese products for the trial production of µTAS chips andthe like used in chemical and biological fields.
30mm

18mm

Glass bonded
to a silicon
wafer
Piezoelectricelement

Silicon and glass
laminated structure

Chip size:
17 x 21 mm

Width: 500µm
Depth: 90µm

Dam cross-section

Photo 2 Recording head (left), µTAS chip (right)

4. Intelligent Micro Modules
Photo 1 The clean room in Hino

2. Pressure Sensors
In semiconductor pressure sensors utilizing
electrostatic capacitance, the sensing element isconfigured of a silicon diaphragm formed by deep etching.
The shape of the diaphragm is optimally designed toachieve excellent precision and reliability. The electrodespacing that determines electrostatic capacity is produced
through silicon micromachining and bonding technologies
controlled with high precision. We have been shippingpressure sensors manufactured with these technologies
for more than 20 years and are currently developing evensmaller and more sophisticated sensors.

Through the application of MEMS, Fuji Electric hasdeveloped a high-density miniature module known as theIntelligent Micro Module (IMM). The IMM is produced bymounting electronic parts, sensors, or the like on a siliconinterposer having built-in passive elements, such as
resistors and capacitors. By manufacturing the interposers
with MEMS technology and equipment, the IMM is suited
to small-scale production of a few thousand. Further,mounting silicon sensors or the like on the interposer not
only helps to produce a smaller sensor module, but also
contributes to an enhanced performance of the module.
Fuji Electric has used this IMM technology to develop
such products as temperature gauges and medicalinstruments. Future plans call for expanding theapplications of IMMs for sensors and other MEMS devices
and developing IMMs suited to high-frequency circuits.
silicon interposer
Bare chipPH
Aluminum electrode
Ceramic
Electrostatic gap
Si diaphragm

C2

BGA
Electronic parts

Electrode

Photo 3 Greater functionality achieved through IMM

C1
Insulator
BasePL
Plan view of a diaphragmFig. 1 Cross-sectional view of a pressure sensor

5. In Conclusion
By developing the MEMS devices described above andproviding MEMS foundry services, we are striving toenhance the added value of new products for ourcustomers. We will continually work toward advances in
MEMS in the hope that you, the customer, will have many
opportunities to take advantage of this distinctivetechnology.

MICRONANO No. 60
MICRONANO is published quarterly by Micromachine Center (MMC) to promote the international exchange ofinformation related to micromachines, R&D and other technical topics, and is circulated free of change. Please send
your comments about MICRONANO to the publisher :Keiichi Aoyagi, Executive Director, Micromachine Center (MMC)
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Internet Home Page h t t p : / / w w w . m m c . o r . j p /Date of Issue : July 20, 2007

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