Consumer Markets to Change MEMS Landscape
Paula Doe, SEMI, San Jose -- Semiconductor International, 6/15/2007
All those new high-volume MEMS devices, such as microphones, oscillators and gyroscopes, for consumer applications are driving big changes in the MEMS industry, said Jean-Christophe Eloy, managing director of Yole Developpement (Lyon, France). “They have to compete with established technologies that are already low-cost,” he noted. “So the price pressure is huge. It’s going to totally change the landscape.” semiconductor makers, will put increasing pressure on the smaller MEMS foundries.
The other major technical trends, said David Monk, manager of automotive sensors operations, Freescale Semiconductor (Lyon, France), are increasing demand for integrating more sensing elements in the system and more logic at the point of sensing. “A tire pressure sensor,” he pointed out, “now includes not just the pressure sensor, but also a temperature sensor, a couple of accelerometers, a voltage sensor, and an RF output to evaluate the pressure for the particular temperature, tell if the car is rolling, identify which tire is which, and report the data.”
Integrating all these sensing elements and logic economically means that the 200 mm MEMS fab also has to find a way to use and reuse as much standard CMOS process equipment as possible, Monk noted. Even for testing its MEMS sensors, Freescale hard docks shaker and pressure testing carts to standard automated test tools. “Some of the formerly custom processes are also becoming more standard, as processes formerly unique to MEMS become more commonly used for things like wafer stacking and through silicon vias,” he pointed out. “Sacrificial etch is becoming more like vapor phase etch.”
MEMS devices will be competing, not just against already low-cost conventional devices, but against those conventional devices improved by MEMS technology. One of the new MEMS products moving into volume production to replace conventional components is the MEMS-based CMOS oscillator from new suppliers like Discera Inc. (San Jose), bringing smaller size and lower costs to the mature quartz crystal oscillator market.
Discera is ramping production of its MOS1 oscillator, with its MEMS resonator stacked on top of ASIC circuitry. The resonator is hermetically sealed at the foundry at the wafer level, so it can be treated as a conventional IC, and both dies are enclosed in a conventional low-cost plastic package instead of the hermetic packaging needed for a typical quartz oscillator, potentially bringing down costs.
But quartz crystal makers aren’t standing idly by to let their market go to silicon. They, too, are turning to MEMS process to shape the quartz crystal. Though quartz requires a more non-conventional CMOS process to form the desired shape, some quartz companies are adopting MEMS processes to make their low-frequency products. “Introducing semiconductor-like batch fabrication and packaging for mechanical devices is going to have a huge impact,” said Wan-Thai Hsu, Discera’s CTO. “Whoever can most quickly adopt into conventional semiconductor manufacturing will succeed.”
Eloy, Monk and Hsu will be among the featured speakers discussing these ideas and other trends and technologies at the Emerging Technologies & Markets TechXPOT MEMS session on Wednesday, July 18, at SEMICON West in San Francisco. For more information, visit www.semiconwest.org.