Portland, Ore. Since the '60s, microelectromechanical systems have struggled to enter the mainstream. With the success of selected MEMS applications, more players are entering the arena. But few have aimed at a larger market segment than SiTime Corp., whose MEMS-First oscillator lines are meant to be pin-for-pin compatible with quartz crystal oscillators.
"We plan to revolutionize the quartz-crystal industry by offering a silicon MEMS alternative that's completely compatible with standard CMOS processing," said Joe Brown, manager of strategic alliances at SiTime. "Vacuum tubes were replaced by transistors, and quartz crystals now have the opportunity to be displaced by silicon technology."
MEMS first became a high-volume industry with air bag sensors like the iMEMS accelerometers from Analog Devices Inc. and later with the digital-light processing (DLP) chips from Texas Instruments Inc. Most recently, Akustica Inc.'s sensor-silicon MEMS microphone has attracted attention. Now SiTime (Sunnyvale, Calif.) is bidding to become an even higher-volume player, since virtually every electronic device produced today uses a quartz-crystal oscillator as its time base.
Gartner Inc. (www.gartner.com) calls the market for analog quartz crystals relatively flat at over $1 billion yearly, with an average selling price of 15 cents on shipments of billions of units per year. Even while still in sampling mode, SiTime has started tapping that vast market by selling more than a million units of its prototypes. Full-volume fabrication of final production units from SiTime, which is fabless, is slated for later in 2006.
"The consensus seems to be that MEMS oscillators' performance is competitive with traditional crystals in most applications," said Stephen Cullen, a contributing analyst at In-Stat (www.in-stat.com). "But I expect the initial applications to be in places where their smaller size can justify a price premium."
In the long term, SiTime and competitors like Discera Inc. (San Jose, Calif.) and Innovative Biotechnologies International Inc. (Grand Island, N.Y.), may sidestep the issue. Instead of competing with the low cost of quartz crystals, they would eliminate them by integrating MEMS time bases onto CMOS chips.
"The long-term advantage," Cullen said, "is the ability to integrate MEMS and CMOS silicon on the same chip, which should lead to further size reductions and ultimately lower overall cost. The end point could be a MEMS clock integrated into every chip that needs one, rather than deriving multiple clock signals from a single crystal."
SiTime intends to realize this single-chip solution by licensing its MEMS oscillators to consumer chip makers themselves, so that the MEMS time bases can be integrated onto the CMOS chips alongside an application's electronic circuitry.
"Our technology is so straightforward that all the major semiconductor manufacturers, from LSI Logic to Actel to Cypress Semiconductor, have embraced [it] because it sits right in line with their own plans," said John McDonald, vice president of marketing at SiTime.
The one-chip solution will require CMOS chip makers to retool their existing dice to work with integrated MEMS time bases, which may take many years. As an interim solution, SiTime plans next to introduce a special two-chip solution that stacks its MEMs dice piggyback on top of standard CMOS dice to supply all their timing signals from above.
For major consumer chip manufacturers, both the one- and two-chip solutions have a hidden advantage over quartz crystals: the ability to have several clock frequencies feeding multiple phase-locked loops (PLLs) on a single chip. Thus, all the timing signals for an entire chip could be packed into the piggyback MEMS die, reducing the complexity of most consumer chips made today and potentially offsetting the higher cost of MEMS oscillators when compared with single-frequency quartz crystals.
"By altering the geometry of the tuning fork," Brown said, "multiple frequencies from multiple oscillators can be embedded into the first four layers of a CMOS wafer, thereby giving every chip access to as many different time bases as is required."