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Aug. 26, 2003 — Standards in the MEMS industry may have taken a small step with the recent publication of National Institute of Standards and Technology (NIST) micromachine measurements, but the larger debate continues over standardization of such a diverse industry.
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The NIST test procedures measure length and other properties in the thin film substrates used to make MEMS. Industry leaders say they hope the standards, recently published in the Annual Book of ASTM International Standards, will lead to more efficient manufacturing, improved reliability and greater trust from MEMS purchasers.
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After years of effort, the NIST procedures are the first that have been publicly announced, said MEMS Industry Group spokeswoman Ellen McDevitt. The test procedures may be “tiny, little standards,” she said, but they are nevertheless “one small step in the right direction.
“Companies that have realized success in the MEMS industry have done so by using their own standards,” McDevitt added. “We’re hopeful this is key to MEMS’ widespread success.”
The standards consist of three test procedures for the thin films used in metrology to make MEMS, according to NIST electronics engineer Janet Marshall. She said the tests can help manufacturers determine the stress limitations of MEMS substrates and improve fabrication yields.
Marshall said MEMS makers may also determine the elasticity of materials using the NIST standards to calculate how much the substrates bend. “You can determine how long to make the cantilever in design before you’ll have problems with stress,” she said. “We know and can characterize the elastic properties. That’s the commodity the MEMS designer wants most.”
All three tests can be performed with the same equipment — an optical profilometer or optical interferometer — that make tiny measurements by using the interference of two beams of light.
Woodbury, N.Y.-based Veeco Instruments Inc. has already been working on a suite of industry standards. Erik Novak, Veeco’s director of research and development, said standard practices are critical because of the diversity of MEMS devices. “Reliability is considered the number-one barrier to greater acceptance of MEMS technology,” Novak said. “Standardization will help alleviate many concerns in this area, as manufacturers can easily confirm good performance of their products.”
Joe Brown, regional director for Suss MicroTec, a German MEMS production and test equipment manufacturer, said standards do help reduce cost as producers can more efficiently develop infrastructure. But Brown referred to other standards efforts — such as those from the International MEMS Steering Group (IMSG), Semiconductor Equipment Materials International (SEMI) and the Micro and Nano Commercialization Education Foundation (MANCEF) — and said the wide array of MEMS devices may require separation within the industry.
“MEMS technologies being so diverse will bring some level of complexity to the creation of standards,” he said. “Perhaps MEMS will need to break out into subgroups such as RF, bio, power, optical and sensors in order to focus the efforts and meet the goal.”
MANCEF President Roger Grace stresses the importance of an international scope and said that standards increase time to market, produce better and cheaper products, and are accompanied by an easier process for companies “shopping” their MEMS designs. “If there’s at least some processes that have been defined as best they can, there will be a commonality there and everyone can bid on the same thing,” he said, referring to MANCEF’s work with SEMI on two MEMS process standards.
Differentiating among process, packaging and testing standards, Grace said the NIST standards were needed, but were only part of the total standards solution. “There is a well-defined hierarchy of testing issues,” Grace said. “The people at NIST are in the testing area. That’s where they have gained their reputation, making measurements like these.”
The ASTM standards from NIST are critical to providing good data and ensuring integrity from instruments, said Rick Manello, vice president of sales and marketing of MEMS at Umech Technologies LLC, a nanomeasurement company in Watertown, Mass.
Stuart Brown, Boston office director for Exponent, an engineering and scientific consulting firm, said the MEMS industry has suffered because of an absence of standards, making it difficult for manufacturers to specify their materials and for customers to specify their needs. “It will make MEMS manufacturers more confident that their devices can actually do what they claim to do because there is an industry accepted way of evaluating performance,” Brown said.
Many in the industry stress the need for standards in production and packaging to continue evolving, while others doubt the industry can ever reach complete standardization. “By and large, these are custom devices with custom processes,” said In-Stat/MDR senior analyst Marlene Bourne. “Some believe there can be standards for a number of things early, but because of the custom nature, it won’t ever be fully standardized like the semiconductor industry.”
There are calls to let the market determine the most accepted way of doing things, along with concerns that the MEMS industry is just too immature for standards.
“It’s difficult to say you’re going to have standards in MEMS,” said Bruce Alton, vice president of marketing and business development for Micralyne Inc., an Edmonton, Alberta-based MEMS manufacturer. “The manufacturing processes are very immature and the end products are very diverse. The manufacturing processes have not matured to the state for standards like the semiconductor industry. There are concerns it could stifle innovation.”