Members' Profiles

Oki Electric Industry
Co., Ltd.

1. The Challenge of Micromachine Technology
Oki Electric first became involved in
micromachine/MEMS-related technology in the 70s by
developing an anisotropic etching technique for siliconthat was applied to the production of high-voltage
thyristor switches used in electronic exchanges. First,
KOH is used to etch about 50 microns from the surface
of a silicon wafer, forming a V-shaped channel. Afteroxidizing the surface of the wafer, the channel isimplanted with polysilicon. The silicon substrate on
the bottom of the wafer is polished, ultimately forminga high-voltage device on a silicon island surrounded byan oxide layer. The technology was developed by
Nippon Telegraph and Telephone Public Corporation(present-day NTT). Oki Electric also participated as amember of a fact-finding committee (chairman: Prof.
Kyoichi Ikeda, Department of Mechanical Systems
Engineering, Faculty of Technology, Tokyo Universityof Agriculture and Technology) concerned with theconcept of a foundry network system for micro andnano production technologies and has actively worked
toward achieving practical MEMS devices.

Fumio Ichikawa
General Manager of the VLSI Research Center

outer dimensions equivalent to the size of thesemiconductor chip. Oki Electric is developing a nextgeneration rerouting technology for forming Hi-Q
passive devices (e.g. inductors and capacitors) on thesurface of semiconductor chips by decreasing the size
and increasing the layers. In this way, passive devices
that to date have been provided externally can be built
into high value-added semiconductor packages (nextgeneration W-CSP).
(3) Optical Interconnections
Electric wiring on printed circuit boards cannot
keep pace with the decrease in size of LSI wiring andthe improvements in clock speed, resulting in a
problem known as an I/O bottleneck that limits theperformance of the overall system. Opticalinterconnections are attracting attention as atechnology for solving this problem. At Oki Electric,
we are studying optical chip interconnections using
free space based on the understanding that the ability
to increase channel density, enabling light to crosswithout interference, can be used to achieve
multichannel interconnections over short distances.

2. Development of Micromachine Technology(1) Accelerometer
Oki Electric is developing small, high-performance
3-axis accelerometers for use in portable devices, invehicle units, games, industrial equipment, security
equipment, and the like.
(2) RF-MEMS/W-CSP
Using a photolithography rerouting technique, weare developing and mass-producing wafer level CSP(W-CSP), which are extremely thin, light-weight, andcompact packages ideal for mobile devices and haveThree-axis accelerometer

3. Future Challenges
In addition to our silicon processing technologies
fostered through many years of LSI production, Oki
Electric works closely with its customers to provide a
micromachine/MEMS foundry service based onprocess control and quality control technologies thathave been shaped by strict market qualityrequirements. Oki Electric is flexible in supporting
various types of services, from undertaking part of theclient's processes to undertaking the entire process
and design, including joint projects with alliancepartners.

RF-MEMS/W-CSP

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