MEMS on SOI – Growing Fast and Faster

By Adele Hars

In the latest ASN posting by Dr. Eric Mounier of Yole Developpement, “SOI for MEMS: A Promising Material”, he notes that SOI MEMS is growing at a CAGR (2011-2015) of 15.6%, compared to 8.1% for bulk silicon-based solutions.

MEMS designers are doing amazing things on SOI – which would explain that impressive growth rate.

The first application of the tiny SOI-MEMS Nanopump™ is for treating diabetes. (Courtesy: Debiotech)

One of my favorites is Debiotech’s tiny insulin Nanopump(tm) targeting diabetes, fabbed by ST. As Debiotech’s Laurent-Dominique Piveteau noted, “…the use of SOI wafers for fabricating the Nanopump MEMS device has significant medical and economic advantages. The SOI-based structure allows for the highest reliability in the smallest possible package, enabling very tight control and precision of the pumping mechanism. The flow rate is steady, and it is insensitive to pressure, temperature, viscosity and aging. It also offers extreme dosing precision.”

Reasons cited by other contributors for using SOI for MEMS include:

• Eliminating the stress problems common in polysilicon;
• Ensuring well-defined film thickness for more accurate oscillation frequency of moving parts;
• Providing greater surface and sidewall smoothness;
• Enabling thinner structures;
• Increasing thermal conductivity of MEMS components.

But the bottom line is that it’s the most cost-effective solution for their state-of-the-art MEMS devices.

MEMS also figure in two of the most recent ASN Buzz postings:

• Freescale and Leti just celebrated 10 years of SOI-MEMS collaboration, which includes producing a million SOI-based accelerometers a year for airbag and ESC apps in the automotive market.
• SiTime has expanded its line of SOI-MEMS-based silicon timing solutions with the industry’s lowest power high-frequency oscillator. With 85% market share and over 35 million devices shipped, SiTime says it is driving the $5 Billion timing market’s transition to 100% silicon-based timing.

In the next few weeks, we’ll also be posting a new article by Soitec on their Smart Stacking(tm) technology for the next generation of MEMS with pre-etched cavities, among other things.

If you’d like to see more of the why’s and wherefore’s of SOI-MEMS apps, just type “MEMS” into ASN’s search engine. You’ll get dozens of pieces from and about leaders like ST, ADI, Denso, VTI, Tronics, IBM and more.

VTI's SOI-MEMS multi-axis accelerometer is the “stride sensor chip” in the miCoach real-time training system (Courtesy: VTI Technologies, adidas and Samsung)

It’s a pretty fragmented world, still, so if you know cool SOI-MEMS apps we should be covering, would you let me know?