MEMS Foundry Service Provided by Oki Electric Industry Co., Ltd.
Nobuo Ozawa
Manager, MEMS Business Team, WP Business Division,
Silicon Manufacturing Company
Oki Electric Industry Co., Ltd.
1. Overview

2. Features of the foundry service

The MEMS Foundry Service at Oki Electric
originated as a foundry service for silicon LSI. While
the LSI foundry service was limited to wafer
processing methods of the 1980s in the beginning, thisservice has now expanded to include mask production,
wafer processing, testing, assembly, and LSI testing.
Based on the development of these semiconductor
devices and processing and production techniques
accumulated during manufacturing, beginning in the1990s Oki Electric began offering its customers MEMS
manufacturing technology through silicon processing
as a part of its silicon foundry service. Some of theprocesses for the MEMS foundry were developed asuser-specific processes during the 1990s, but werelimited to processes that could be supported on asilicon LSI production line at that time. Beginningfrom the late 1990s, the range of supported processes
gradually expanded.
We are not preparing to offer any packaging
services at this time. However, Oki Electric possesses
technologies that are applicable to MEMS packaging,such as wafer-level chip size package (W-CSP) andmulti-chip package (MCP). Hence, there is potential
for developing a foundry service that encompasses
packaging.
MEMS-specific processing techniques are being
incorporated into silicon semiconductor processing todevelop MEMS at the single-element level. Oki
Electric is also conducting R&D on integrated MEMS
that combine LSI and MEMS to produce systematic
devices possessing signal processing andcommunication functions.
By effectively employing the processing andmanufacturing techniques obtained through MEMS
development in the MEMS foundry, we hope toprovide customers with a higher quality of service.

Oki Electric is applying its twenty years of experiencein the silicon foundry and its experience in LSI processes
from development to mass production to the MEMS
foundry. We are pursuing a wide range of foundry services
from development and trial production to mass production.
Since development and trial production are primarily
conducted at Miyazaki Oki Electric (located in Kiyotakecho, Miyazaki Prefecture), which has a mass production
line, the transition from the trial production stage to massproduction is extremely smooth. Further, by a special
control division supervises the production facilities,enabling us to provide trial production and mass
production results with high reproducibility.
Including processing of partially contracted allianceproducts, the MEMS foundry has manufactured
capacitive pressure sensors, piezoresistive pressure
sensors, accelerometers, and silicon microlenses in trial
production and mass production.
3. Conclusion
The MEMS Foundry Service at Oki Electric works
closely with its customers while producing MEMS
products. The Service develops optimal processes suited
to the user's concept of the product and the device
design, based on silicon processing and analysis
techniques, as well as process control and quality control
techniques, cultivated over many years of LSIdevelopment and manufacturing.
By applying its MEMS manufacturing technology andknow-how not only to its own products, but also to a wide
range of foundry projects, Oki Electric hopes to provide
an environment that fosters the production anddevelopment of MEMS products.
For further information, send e-mail to:
SiSC-MEMS@oki.com
Outline of the Oki Electric MEMS Foundry Service

Step

Step 1:
Step 3:
Step 2:
Partial process Stand-alone element Integrated MEMS
SIP technologySOC technology

Transistor

Scope of service

From small-lot trial production to mass-production

Cleanliness

10-1000 class

Wafer diameter

4 and 6 inch

ISO and other certification

ISO9001, ISO14000

Process technologies

Silicon wafer processes-Bulk micromachining-SOI micromachining

Record of mass
/ trial production(including in-house products)

Accelerometers, pressure sensors,microlenses, various film deposition,etching, etc.

Integrated MEMS
MEMS
processing

Copper inductor

MEMS + LSI

Copper post
/WCSP
Silicon lensG sensor3