Sharply falling prices are creating a fast-growing market for commercial infrared sensors, for everything from night vision systems for automobiles and boats, to locating leaks in roofing and scanning airline passengers for fevers.
These microbolometers are currently one of the most promising emerging applications for MEMS. In the last couple of years, prices for the IR sensing systems have plummeted from more than $10,000 down to around $6,000 for some applications, expanding commercial demand. In its recent study, "Uncooled IR Cameras & Detectors for Thermography and Vision Markets—2010" (Figure 1) Yole projects that upcoming technology advances in IR detectors will continue to drive down camera prices by as much as 60%, spurring 24% annual growth in unit demand over the next five years, and creating a $3.4 billion market for IR cameras for vision enhancement and thermal sensing by 2015.
Moving from Military to Commercial Markets
Infrared sensors have been primarily used in military night vision systems, although those systems typically use a more complex and expensive cooled technology. The smaller, lower cost, MEMS microbolometers were also first developed for military applications—to bring night vision to more soldiers' rifle sights and to more trucks in war zones—and most suppliers continue to focus on the military market. However, leading suppliers FLIR Systems Inc. (Portland, OR) and ULIS (Veurey-Voroize, France) have taken advantage of this core market to ramp up volumes and to lower costs, creating a serious commercial market that accounts for more than 50% of total demand for these dual-use devices.
The biggest commercial market is for vision enhancement systems, which account for about two thirds of sales. Closed-circuit security cameras are currently the largest market, and potentially the biggest opportunity, because most systems would be more useful if they had IR night vision capability, a feature manufacturers would add if the price were right. Cities want to equip their police and firemen with vision enhancement systems to find people in smoke and low light conditions. Boaters want to be able to see obstacles at night. Drivers want to avoid deer and pedestrians crossing the road in the dark.
Though only a few thousand automotive night vision systems are in use today, and those in very high-end cars, multiple development projects are in the works, spurred in part by a European mandate for pedestrian recognition systems in mid- and high-end cars by 2015. Progress in image enhancement software that makes it easier to distinguish—or even automatically detect—people and animals is also likely to start generating more interest in these systems.
The rest of the IR sensor market belongs to thermal sensing, which typically uses smaller-format sensors to create a color picture of heat patterns. Thermal scanning tools have long been used by specialty consultants to identify abnormal heating in electrical or mechanical equipment but now plant maintenance crews and general contractors are also starting to use affordable thermal scanners, with software that makes the output easier to understand, to quickly locate problems including worn bearings, imminent electrical failures, leaks in roofs and plumbing, and building insulation issues. Government incentives for energy savings, especially in Europe, are helping to drive demand. Airports worldwide also bought the tools to scan arriving passengers for fever during the swine flu scare. The small-format sensors used in these tools will see prices decline particularly sharply, to further expand applications going forward.
MEMS Technology Will Keep Costs Coming Down
To date, the two major specialty IR sensor suppliers have driven costs down by adopting volume MEMS technologies. However, mainstream MEMS suppliers attracted to the growing market are poised to introduce competing products of their own over the next few years, made with potentially disruptive new technologies that are likely to reduce costs further.
Microbolometers are basically arrays of pixels of IR-sensitive vanadium oxide or amorphous silicon thin film, which change resistance in response to IR radiation. Each pixel is suspended on a MEMS microbridge to isolate it from other heat sources. Although neither material is CMOS-compatible, commercial market leader FLIR Systems Inc. (Portland, OR) and the other major commercial supplier ULIS (Veurey-Voroize, France), are using above-CMOS approaches in which the IR-sensitive pixel arrays are grown over the Read Out Integrated Circuit (ROIC) CMOS wafer.
The crowd of new entrants with alternative technologies in the pipeline includes MEMS suppliers Sensonor and Robert Bosch. Bosch plans to use the porous silicon process it uses to make membranes for pressure sensors to make a thermally isolated IR-sensitive membrane instead, targeting night vision systems for its core automotive MEMS customers. Japanese chip makers Toshiba and Mitsubishi Electric are each working on making IR detectors on silicon, potentially relying on sophisticated software to enhance the initially lower image quality.
Whatever the approach to making the IR sensor, packaging will move to the same kinds of wafer-level packaging, 3D stacking with through-silicon vias, and wafer-level optics used in CMOS image sensors. These low-cost packaging technologies have been a major driver for the 25x price drop and 100x volume growth in the CMOS image sensor market over the last ten years, and we expect IR sensors to follow a similar path. That could mean $10 IR detectors in 2020, and low-end IR cameras for as little as $100, creating a 4-million unit market.
ABOUT THE AUTHOR
Dr. Eric Mounier has a PhD in microelectronics from the INPG in Grenoble. He is a co-founder of Yole Développement, a market research company based in France, where he is in charge of market analysis for MEMS, equipment & materials. He can be reached at [email protected].