The use of microelectromechanical systems (MEMS) has stirred up a great deal of interest in many markets. Just how important is MEMS technology? According to Gordon Moore, chairman emeritus of Intel Inc., Santa Clara, Calif., "MEMS is a really intriguing technology, and I believe it will have a significant impact in the next century." In fact, many engineers believe that MEMS devices will have as profound an effect on our everyday lives in the next decade as the microchip had in the previous one. Design teams at Xerox, Webster, New York; Texas Instruments, Dallas, Tex.; and many small start-ups are already researching potential applications that range from rudderless aircraft to buildings that self-adjust during an earthquake.
MEMS are tiny mechanical systems—sensors, motors, nozzles, valves, and others—that fit onto the surface of computer chips. They're created using the same semiconductor technology as ICs. For example, to create a MEMS pressure transducer, most of the surface material in a defined area of a silicon wafer is etched away. The result is a transparent diaphragm that can be as thin as a single micron. Resistors are then embedded into the surface of this diaphragm and used to translate the slightest movement of the membrane into a voltage.
Although this all sounds pretty futuristic, don't dismiss MEMS as a "blue-sky" technology. Engineering teams see the technology becoming more mainstream and highly applicable for enhancing today's consumer electronics equipment (see "MEMS Hits The Big Time,"). In fact, any device that requires motion sensitivity is a candidate for MEMS, including computer mice, camcorders, and virtual-reality headsets.
Challenges Of MEMS
The increasing attention paid to applications, coupled with the technology's cost effectiveness has brought about rapid progress in MEMS. But for all the benefits it offers, there are still formidable hurdles that need to be addressed before it can become truly mainstreamed.
One major obstacle is the lack of a smooth communications link between the mechanical and electronic worlds. Engineering teams charged with the design of integrated microelectromechanical systems are particularly conscious of this gap, and, in many cases, are still constrained by an "over-the-wall" approach to integration. Typically, each group within the team handles only the tools traditionally associated with its single discipline, throwing the project over the wall to the next group when its portion of the design is completed. With no common interface, such a separatist approach can result in catastrophe when prototype testing reveals a design flaw requiring additional iterations. One group may fix the error, but what will the repercussions be on the rest of the design, and who will fix them?
For example, none of the information derived from using 3D field solvers on MEMS structures information can be automatically transferred to an IC design tool. Microsystems engineers painstakingly identify material properties and boundary conditions to build a mesh so that the field solver can run a 3D finite-element analysis. The tool then predicts the amount of stress and strain in the structures, structural movement, or any other possible effects. But the information is useless without a means to incorporate the data into an electronic design format that other tools can exploit.
The urgency of developing a completely integrated solution for MEMS design can be demonstrated by looking at automotive airbag system designs. Clearly the airbag design team must consist of engineers across different disciplines. One group requires a finite element method (FEM) simulator to design the MEMS device, while another needs an electrical simulator to design the circuitry. Without an integrated approach, each group must spend precious days just translating data from the other group, a task that adds no value to the design, and that almost inevitably introduces errors into the process.
A secondary hurdle is enabling engineering teams to make full use of pre-existing intellectual property (IP) in MEMS design. The ability to smoothly integrate cores into a system-on-silicon architecture provides designers with both the latest functionality and a major productivity gain that can catapult the product to market months ahead of the competition. Until now, designers had to create MEMS by pushing polygons, and understanding the fine details about the target fabrication process. Obviously, this approach demanded exceptional engineering skills, and expanded design schedules and budgets.
To bring MEMS into the mainstream, it is absolutely essential that the difficulties surrounding MEMS design be minimized. One thing is certain: If electronics engineers can use MEMS devices in their system design, without excessive complexity, then market growth will be significantly intensified. And, the potential of that market growth is enormous. According to research from Ernst & Young Entrepreneurs Conseil, Paris, France, in 1996, the MEMS market was $12 billion for devices and $34 billion for systems. The same firm estimates that by the year 2002, the market will have grown to $34 billion for devices and $96 billion for systems.