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MEMS face quartz-crystal giants

Posted: 17 Mar 2008 ?? ?Print Version ?Bookmark and Share

Keywords:MEMS? quartz crystal? piezoelectric material?

Expect a battle between startups' MEMS chips, like this SiTime device, and those of quartz crystal vendors.

Today, quartz crystals provide the heartbeat for nearly every electronic system, with annual volumes approaching 10 billion units.

Electronic circuitry alone cannot generate the precisely spaced pulses that keep gates in synchronization in digital systems, or the rock-solid oscillations that keep analog frequencies tuned. In this sense, MEMS represent the final frontier in microminiaturization!downsizing this necessary mechanical reference signal from the millimeter scale of quartz crystals to the nanoscale of ICs.

More room
Industrial giants such as Epson Toyocom Corp., the world's largest supplier, provide quartz-crystal timing chips. Two upstart makers of MEMS timing chips, SiTime Corp. and Discera Inc., think there certainly is room for them in this sector, with its mammoth volumes. But Epson and the other large timing chip companies are not going to sit still while the MEMS competitors carve out chunks of their lucrative markets. Epson is already offering "QMEMS" technology-downsized quartz-crystal timers that descend into the submillimeter-size regime.

Startups will have only a few years of head start before Epson and the other behemoths respond to the popularity of MEMS timing chips with MEMS offerings of their own. SiTime and Discera have the biggest lead in the race to downsize mechanical timing references to the nanoscale. Both companies have invested several years of research and development effort into matching the precise timing signals of quartz crystals (which are based on the principles of physics governing piezoelectric materials), deploying tiny silicon mechanical structures!silicon "tuning forks"!with an equal measure of stability and precision.

However, if SiTime and Discera do not carve out niches of their own soon, they risk being crushed by the deeper pockets of the established quartz-crystal chipmakers.

SiTime vs. Discera
For now, SiTime and Discera are running neck and neck in MEMS chips for timing applications. Both companies went into volume production last year with chips that are pin-for-pin compatible with the quartz-crystal oscillators that today sell in the billions of units annually. Besides having compatible parts shipping in the hundreds of thousands per month, both companies are also well-funded fabless CMOS chipmakers using foundries. SiTime uses Jazz Semiconductor for the SiT8002, and Discera uses Dalsa Semiconductor for the MOS1.

When you compare the investors and distributors that both startups have attracted, you find similarities and differences. And when you compare their technologies!SiTime's Bosch-licensed Deep Reactive Ion Etching (DRIE) and Discera's more-conventional surface micromachining approach!you find pluses and minuses to both.

"SiTime's device is the most innovative, and I believe it's better positioned for future improvements, scaling, integration and cost reductions," said John Boyd, technology manager at Semiconductor Insights. "However, removal of the encapsulant and subsequent cleaning fluid is challenging, and may involve some expensive process techniques that minimize surface tension and allow removal of the etching and cleaning fluids from the channels remaining after encapsulant removal."

The Discera approach, by contrast, "forms the MEMS structure more conventionally, resulting in a device that needs to be packaged hermetically sealed separately after singulation of the die, and then integrated with the control circuitry in a flip-chip module or something of this sort," Boyd said. "This results in a much larger package size, but it is known technology, using CMOS-compatible processing."

The startups also differ in their strategic alliances. SiTime has allied itself with Micro Crystal, a quartz-crystal division of Swatch Group Inc. that specializes in consumer chips. Discera, meanwhile, has allied with Vectron International Inc., a U.S. quartz-crystal maker specializing in high precision, avionic and military-specification chips.

The differences in business alliances are also reflected in the companies' different business strategies. SiTime recently ousted its technology-oriented CEO!MEMS pioneer Kurt Peterson!for a business-oriented veteran, Rajesh Vashist. The new CEO's self-proclaimed aim is to differentiate SiTime with a "home run" strategy that signs up major customers in the consumer market for high-volume sales of lower-priced parts.

Discera's CEO, Tom Willey, on the other hand, intends to build the business on multiple "base hits" by addressing the specific needs of niche markets in military, avionics and other high-precision applications.

- R. Colin Johnson
EE Times

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