Tag Archives: accelerometer

Evolving Intelligence with Sensors

Contributed by Michael Stanley, Freescale Semiconductor

Originally posted on Freescale’s Smart Mobile Devices Embedded Beat blog

I’ve always been fascinated by electronic sensors. The idea of being able to measure and interact with the physical world appeals to the ten-year-old inside me. Not so long ago, if you needed to measure some physical quantity as an input to your system, you bought an analog sensor, hooked up your own signal conditioning circuitry, and fed the result into a dedicated analog-to-digital converter. Over time, engineers demanded, and got, self-contained products which handled those signal conditioning and conversion tasks for them. Continue reading

Top 30 MEMS ranking: Total revenues slip 5%, but innovation still spurs growth for many

Contributed by Jérôme Mouly, MEMS Technology and Market Analyst,Yole Développement

Total MEMS revenues from the Top 30 MEMS suppliers tracked by Yole Développement slipped 5% in 2009, as the worldwide downturn hit consumer and automotive sales. But innovation still continued to sell. Companies with new, high-end products managed healthy growth, led by an eye-popping 500% increase at InvenSense, Inc., rapidly building up a $95M business in gyroscopes for consumer electronics. Continue reading

HP Finds Novel Use for MEMS Inkjet Printhead Technology

HP and Shell are working together to re-purpose HP’s MEMS technology for use in oil drilling and exploration (Drilling with print heads: Shell and HP develop seismic sensor system – 15/02/2010 – Computer Weekly). Continue reading

Sensors, sensors everywhere: MEMS and the “Internet of Things”

Robert MacManus posted an interesting piece on ReadWriteWeb recently (see 2010 Trend: Sensors & Mobile Phones) in their series on the “Internet of Things”–where devices are connected to the Internet to provide us with more data and functionality. Although he doesn’t call it MEMS by name, he makes the point that cell phones are becoming much more than communications devices; cell phones and mobile devices are essentially pocket-sized platforms for sensors. And, yes, many of these sensors are MEMS devices! Continue reading

Analog Devices accelerometer adds intelligent sensing to mountain bike suspension system

This will appeal to the hardcore cycling enthusiasts amongst us: Analog Devices recently demoed an electronic mountain bike suspension system featuring its iMEMS® accelerometers. Continue reading

Kionix Sale for $233.0 Million to Rohm in a Booming Consumer Electronics MEMS Inertial Market

Contributed by Laurent Robin, MEMS Analyst, Yole Développement
Until 2009, the MEMS industry was traditionally driven by the automotive area. This was true for pressure sensors for instance, and also for inertial sensors: MEMS accelerometers for airbags became the first high-volume application for MEMS inertial sensors. But whereas the market for motion sensors is now mature for many automotive applications, more and more consumer electronic devices integrate MEMS accelerometers and gyroscopes.

Often considered as more mature than the gyroscope industry, the accelerometer industry has seen a significant announcement in October: the fast-growing MEMS accelerometer manufacturer Kionix (USA) was acquired by the Japanese company Rohm (J). Continue reading

Nokia Beats Apple to Compass-in-Phone

Contributed by St.J. Dixon-Warren, Manager, Process Analysis, Chipworks Inc.

In a good example of Apple’s superior media hype, when the latest 3GS iPhone was launched in June, some note was made of the addition of an electronic compass to improve the accuracy of the GPS map applications. The mobile phone media appears to have completely missed commenting on the fact that the Nokia N97 smart phone also features an electronic compass, and was released some six months before the iPhone 3GS. According to iSuppli’s web teardown the iPhone contains an AKM AK8973 compass chip. Continue reading

Chipworks Looks Inside the Freescale HARMEMS Process

By St.J. Dixon-Warren, Manager, Process Engineering, Chipworks

The Freescale MMA6222AEG Accelerometer is targeted for automotive applications and is implemented in a relatively large 13.0 mm x 7.6 mm x 3.3 mm thick 20-LEAD SOIC package. The MMA6222AEG is fabricated with Freescale’s HARMEMS process using a thick SOI layer to form the mechanical layer of the MEMS structure. Chipworks has just completed a full MEMS Process Review analysis of this market leading technology.


Freescale MMA6222AEG Package

Cross-sectional analysis of the package reveals two chips: a MEMS chip with a hermetic cap and a separate ASIC, both mounted upside down beneath the package lead frame. Unlike most MEMS device we analyze, the MEMS chip is encapsulated in silicone gel, likely to reduce packaging stress on the MEMS die.


Freescale MMA6222AEG Package Cross Section

Detailed examination shows the MEMS layer, sandwiched between the MEMS die and the MEMS cap. The thick SOI layer provides increased stiffness and greater mass for the moving mechanical element, plus increased electrical capacitance. This should give increased sensitivity compared to Freescale’s standard surface micromachined process, which we found in the Freescale MMA7455L, where the mechanical poly 2 layer was only ~3 µm thick.


Freescale MMA6222AEG MEMS Structure Cross Section

The HARMEMS SOI process uses a deposited polysilicon layer, with air bridges, to form the electrical interconnects for the MEMS die. The SOI process does not permit the use of a buried poly for the electrical interconnects. The poly air bridges would have been formed on a sacrificial layer (likely oxide) after the deep reactive ion etch (DRIE) used to form the MEMS structures. A timed etch is then used to release the MEMS structures.


Freescale MMA6222AEG MEMS Structure Tilt View

The use of single crystal SOI should allow better control of the DRIE process, thus giving better consistency in the mechanical properties of the device; however, the SOI process limits the kinds of anchors that can be used. Essentially, released beams need to be narrow, while anchored structures need to be wide enough to ensure that enough oxide remains to provide a connection to the substrate. It is worth noting that, Freescale’s European competitors, Bosch, ST Microelectronics and SensorDynamics, have chosen to develop a thick polysilicon process which allows for greater flexibility in the formation of interconnect and in the formation of anchors.


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