Consumer Applications Push MEMS to New Volumes
SEMI, San Jose -- Semiconductor International, 6/20/2008 8:01:00 AM
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“Nintendo’s Wii and Apple’s iPhone really got user attention for what could be done with MEMS motion sensors,” said Rob O’Reilly, director of MEMS test at Analog Devices Inc. (Norwood, Mass.). “I got hundreds of calls and e-mails asking if we could do this or that for all types of innovative applications. The handset people all came out of the woodwork.”
The MEMS product line is now among the fastest growing at Analog, according to O’Reilly, based on demand from consumer devices. And the company expects strong growth to continue, as portable device makers look to add more convenient user interfaces, and all sorts of new markets develop — from accessible control systems for the handicapped, to contact microphones for musical instruments, to portable ultrasound systems. “Some time ago, the MEMS user group estimated MEMS per capita was about 1.5 devices per person, and would get up to 2,” he said. “That model has been completely blown away, with the MEMS adoption rates of gaming, GPS, portable media devices, cell phones and cameras. Me personally, I’m up to 6, and I know I’m not alone.”
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That means a whole new kind of volume to deal with, as one cell phone model alone may run 40 million units. “OEMs will soon start asking for that weekly,” O’Reilly said. “You really need to use a foundry to meet this kind of demand.”
Though consumer products have historically had lower overall reliability requirements than conventional automotive applications, the demands are increasing. Consumer products are more likely to be dropped, mishandled and abused, so their MEMS devices need to be able to withstand much higher gravitational forces, and that presents a big challenge for testing. “We now measure the effects of 50,000 g with capability to measure up to 100,000 g. It’s a huge paradigm shift,” O’Reilly said, “and our customers demand it.”
Digital camera modules, low-power displays, timing and handheld projectors
One of these new, potentially high-volume consumer markets for MEMS devices is incorporating relatively high-quality digital camera functionality into cell phones. Siimpel Corp. (Arcadia, Calif.) said it’s taking a big step in that direction with its MEMS autofocus system, which is slated for introduction within months on a major phone supplier’s camera phone. More than 70% of the 1 billion mobile phones shipped each year include cameras.
Though image sensors have improved, even the higher-resolution camera phones still don’t take digital-camera quality pictures because it’s hard to cram the needed mechanical motor-driven autofocus and shutter systems into a product that small. Siimpel replaces the mechanical parts with silicon MEMS devices. The company integrates the silicon devices to control the motion of the lens assembly, explained Shawn Maloney, vice president of business development. The second-generation product, due out in a commercial phone in the fourth quarter, will integrate the MEMS autofocus and shutter directly into the lens barrel. The module will enable a 5 Mpixel camera with autofocus and integrated shutter all in an 8.5 × 8.5 × 6 mm module.
Another potentially big market is low-power mobile displays, enabling the longer battery times needed for the new mobile applications. Qualcomm MEMS Technologies Inc. (QMT, San Diego) recently introduced a color version of its reflective mirasol display, which uses wavelength interference to get good brightness without a power-consuming backlight. The color of light reflected by QMT’s Interferometric Modulation technology depends on the thickness of the optical cavity, with thicker cavities resonating longer wavelengths and hence reflecting longer-wavelength light. The display uses air gaps of three different thicknesses in RGB color stripes as in many conventional products, but now without the color filter. QMT fabricates the display with its MEMS air gap structure directly on large-area glass substrates, mostly using the existing LCD fab infrastructure.
“One MEMS device can replace a whole set of other elements,” said Brian Gally, director of product management at QMT, noting the potential for much lower production costs. The single MEMS element, with its optical cavity, membrane and reflective films, performs the color selection typically done by the color filter, the light modulation done by the polarizers and the liquid crystal itself, and the memory function done by a transistor backplane.
Also getting close to market are handheld projectors, allowing cell phones or laptops to display large images on most nearby surfaces. Microvison Inc. (Redmond, Wash.) is working with a variety of electronics suppliers to manufacture prototype units, and aims to have its initial MEMS-based display engine out by the end of the year, targeting high-volume consumer products with OEM partners in 2009.
The first volume product using the laser scanning technology is actually a barcode reader released late last year, using a simpler version of the MEMS mirror that oscillates on only one axis to project the scanning laser beam across the barcode, for a low-cost scanner for applications such as warehouses. That serves in part as a vehicle to ramp the company’s fab. “We’ve done demonstrations for years, but now we’re learning scaling,” said Jason Tauscher, Microvision’s manager of MEMS development. “We’re really starting to push volume now and stabilize the process.”
Microvision argues that its laser scanner approach, based on one MEMS mirror that oscillates on two axes within its frame, allows a smaller, lower-power device compared with competing approaches. Each pixel is generated by mixing red, green and blue laser beams into one beam of the desired color, which the scanning mirror then directs toward the right spot on the projection surface, rapidly reproducing the image pixel by pixel.
Silicon Clocks (Fremont, Calif.), meanwhile, targets applications combining multiple resonators in one system, which it says the one-chip system-on-a-chip (SoC) solution makes practical in size and cost. Among the first likely applications are high-end consumer products such as enhanced phones, PDAs, digital TVs or SLR cameras, where the integration of multiple resonators can reduce size and cost and improve standby power. Initial timing products are expected to ship later this year, with adoption of multi-resonator devices driving high growth of MEMS timing solutions in 2009 and 2010.
MEMS foundry Innovative Micro Technology (IMT, Santa Barbara, Calif.) is also seeing an increase of applications in the RF space, said CEO John Foster, now working on five with five RF switching products now sampling. The company is also seeing more biomedical applications, from a chip that weighs single bacteria to one that sorts out a person’s stem cells for treating diseases from heart failure to diabetes.
However, consumer-electronics style mass production of MEMS at ever lower prices may not be as easy as some may expect. MEMS is not as mature an industry as many assume, according to Foster. “We’re like the little brother of the semiconductor industry,” he said. “That means we benefit from the fact that equipment and materials are already developed — but also, the expectations can be unreasonably high.” What’s more, he said, the MEMS industry may never mature like CMOS. “CMOS is making transistors and connectors. But MEMS are making machines. And people’s imagination for making different kinds of machines is very broad.”
These executives will discuss recent developments in the MEMS market and implications for the supply chain at the Emerging Markets TechXPOT at SEMICON West on Tuesday, July 15, at Moscone West, Level 2. More information is available on the SEMICON West 2008 website.
