Published in April / May 2010 issue of Chip Design Magazine
Microelectromechanical systems (MEMS) are micro-scale or nano-scale devices. Typically, they’re fabricated in a manner similar to integrated circuits (ICs) to exploit the miniaturization, integration, and batch processing benefits of semiconductor manufacturing. Yet unlike ICs, which consist solely of electrical components, MEMS devices combine technologies from multiple physical domains. They may contain electrical, mechanical, optical, or fluidic components.
Spurred by growth in consumer electronics, the total market for MEMS is projected to grow more than 40 percent from 2008 to 2012. It will go from just over $7 billion worldwide to over $13 billion, according to market research firm Yole Development. The market for MEMS in mobile phones is expected to grow by more than 4X during this period to $2 billion.
As promising as these forecasts sound, only a few large IDMs are well positioned to benefit from this rapidly growing market. This is due to the specialized expertise, long development time, and high cost of bringing MEMS devices to market. Almost all MEMS devices are tightly integrated with electronics—either on a common silicon substrate or in the same package. Yet MEMS design has traditionally been separated from IC design and verification.
MEMS devices are typically designed by PhD-level experts in such fields as mechanical, optical, and fluidic engineering. They use their own two-dimensional (2D) and three-dimensional (3D), mechanical computer-aided-design (CAD) tools for design entry and finite-element-analysis (FEA) tools for simulation. Eventually, the MEMS design must be handed off to an IC design team in order to go to fabrication. But the handoff typically follows an ad-hoc approach that requires a lot of design re-entry and expert handcrafting of behavioral models for functional verification.
Moreover, MEMS historically requires specialized process development for each design, resulting in a situation often described as “one process, one product.” While there are a number of specialized MEMS foundries, support from pure-play foundries has been very limited. According to one analyst report, it takes an average of four years of development and $45 million in investment to bring a MEMS product to market.
Several trends are converging to make this level of effort and expertise unacceptable—not only for new entrants in the MEMS market, but for the best-positioned IDMs as well. First, the fast-paced consumer-electronics market demands design cycles that are measured in months, not years. In addition, design costs must be such that they can quickly maximize return on investment and profitability.
Secondly, the market is demanding more functionality from MEMS devices. For example, enhanced sensitivity requires that more analog and digital circuits will be placed around MEMS devices. The third trend is the rise of advanced packaging technologies, such as system-in-package (SiP) and chip stacking with through-silicon vias (3D IC). These technologies will allow manufacturers to package all of this functionality more densely, combining multiple MEMS sensors with analog and digital dice in a single package. These technologies will allow manufacturers to package all of this functionality more densely, combining multiple MEMS sensors with analog and multiple digital die in a single package.
These demands make MEMS more susceptible to unwanted coupling between sensing modes as well as between the MEMS sensors and electronics. The present approach to MEMS design—with separate design tools and ad-hoc methods for transferring MEMS designs to IC design and verification tools—is simply not up to these new challenges. The time has come to “democratize” MEMS design and bring it into the IC design mainstream. The result would be reduced design costs and shortened time to market. In addition, the MEMS design would no longer be confined to teams of specialists inside IDMs.
A critical key to accomplishing this “democratization” is to build an integrated design flow for MEMS devices and the electronic circuits with which they interact. A structured design approach should be used that avoids manual handoffs. Companies like Coventor and Cadence are now working together to develop such integrated methodologies. Their goal is to shield IC designers from the complexity of MEMS design while reducing the time, cost, and risk of developing MEMS-enabled products.
Dr. Joost van Kuijk is vice president of marketing and business development at Coventor. Dr. van Kuijk has more than 16 years of experience in the MEMS field, specializing in modeling and simulation. He received a PhD in micro system technology from Twente University, where he also received a diploma in technology information. In addition, Dr. van Kuijk holds an MSc in mechanical and precision engineering from Delft University.