A year and a half from now, your next mobile phone may be smaller and more powerful with the help of new micromachines from IBM.
Last week, the company announced a new process for building RF, or radio frequency, microdevices directly onto chips for cell phones and other wireless devices. The typical cell phone today uses about 10 of the components IBM would like to replace with MEMS versions. The next wave of 3G, or third generation phones, may need even more of these tiny electromechanical filters, switches and capacitors to take advantage of high bandwidth data while conserving power.
RF MEMS have been in development for a decade. But packaging and integrating them into wireless chips has been a challenge that has slowed their incorporation into communication devices.
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The IBM process runs at a relatively cool 400 degrees Celsius, enabling researchers to fabricate and encapsulate very small RF MEMS components such as resonators directly on a wireless chip without harming delicate surrounding circuitry and wiring. Such resonators can act as a frequency reference or to filter specific frequencies.
“If it can be commercialized, this would be an exciting development,” said Marlene Bourne, senior MEMS analyst at In-Stat/MDR. In-Stat expects the market for RF MEMS to grow to nearly $350 million in 2006. Bourne said IBM’s experience in making MEMS devices and chips, as well as its financial resources, work in the company’s favor. But she noted that IBM will compete in the RF MEMS market with companies such as Motorola Inc., Agilent Technologies Inc. and MEMSCAP Inc.
Jennifer Lund, IBM researcher and author of a paper on the project, explained that the process can make RF MEMS resonators about 10 microns in size, compared with existing devices that are as much as several millimeters. Moreover, she said, resonators fabricated “on chip” and directly interconnected with the rest of the chip would conserve power.
Currently, resonators called SAWs or smaller ones developed by Agilent called FBARs (film bulk acoustic resonator), are manufactured as separate small chips that need power to pass signals in and out to the communications device.
According to Lund, the resonators IBM could build directly on a wireless chip are microscopic beam-shaped structures with precise mechanical properties that filter certain radio frequencies. They are also truly “passive” components because they don’t use any electrical power, enabling a wireless device to run longer or divert some of its “power budget” to new, power-hungry applications such as streaming video.
She said the technology is several years away from commercial introduction, but IBM can provide the modeling and design help wireless chip makers may need to build future integrated circuits with RF MEMS. Lund said the group of scientists has met with potential customers to gauge their interest and solicit suggestions.
Integrating RF MEMS components onto a wireless chip may add cost in creating additional masks and layering steps. Cost will also depend on quantity and yield of RF MEMS, and may be offset by enabling new functionality in devices such as supporting multiple transmission modes and higher bandwidth for data.
Bourne also noted that while the market opportunity for RF MEMS could grow to billions of devices, such a high volume market would also demand low-cost components that offer equally miniscule margins.
In addition to resonators, Lund reported, the same process could be used to integrate other types of RF MEMS components such as switches for changing between “send” and “receive” modes. Ultimately, she said, IBM would like to offer a range of RF MEMS devices that can be fabricated together into advanced micromechanical systems.
“That would open up whole new possibilities for device makers,” Lund said. Right now, she said, a typical mobile phone employs as many as 10 resonators. RF MEMS fabrication could squeeze those components into a fraction of current chip real estate, or pack in hundreds of MEMS filters for added performance.
With 3G mobile systems entering service and the next generation in the planning stages, the next 18 months could be where the market meets the need for RF MEMS technology.
“As carriers deploy third-generation wireless networks, the limitations of passive components in devices become an even more imminent issue. While these higher-frequency, broadband networks allow significantly faster data communication, they also require better processing and demand a lot more power from handsets,” said Dave Seeger, senior manager of silicon science and process technology at IBM Research.
In-Stat’s Bourne noted that in addition to IBM, other big players such as Infineon Technologies and Bosch have succeeded in blending conventional chip making with MEMS fabrication. As that integration continues, she believes, “RF MEMS are going to disappear into consumer electronics” to the point where it will become difficult to measure the RF MEMS market.