Solving The Production Problems Of MEMS

Sensors are everywhere and MEMS (Micro Electro Mechanical Systems) are made in their billions with the market being worth billions of dollars. However, there is a huge problem for this industry that stops it growing fast to the trillions. Every type of MEMS sensor must be designed and made using a dedicated, production process that can take five to seven years to bring to market. It is also hard to ramp up production apart from constructing a second identical manufacturing line. There are no economies of scale available as every process is unique.

 

This bottleneck is stopping the vision of IoT of having smart sensor nodes everywhere because ramping up to the trillions of nodes that this could have, would be impossible to produce with current MEMS manufacturing techniques. A British electronics company, Nanusens, has solved this problem with a novel way to make MEMS sensors that uses the same standard production technology used to produce virtually all electronic chips that is called CMOS (Complementary Metal-Oxide Semiconductor). It is used in all the major fabs in the world so that there is no limit to the number of sensors that can be produced.

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Current MEMS devices consist a chip with the moving parts that form the sensor built on the surface of a silicon wafer, and a second chip with all the control electronics. The second chip is easy to make using standard CMOS processes but the first chip, with the tiny moving mechanical parts, is the part that needs proprietary processing and therefore is the limiting factor that prevents rapid increases in production volumes.

 

The Nanusens solution is to make both parts in one chip by shrinking the MEMS part so that it can be formed within the layers of the control chip. The MEMS structure is created with metal layers in the same way that a normal CMOS chip is made. The structure is then released by etching away the surrounding silicon dioxide so that it can move freely.

Nanusens shrink MEMS to create nanosensors within the CMOS layers

 

This sounds simple in theory but, in practice, the released metal MEMS structures distort due to stresses in the metal that are only an issue when the metal is released. This is because the CMOS process was never designed to release metal layers in this fashion. The team at Nanusens has spent years researching and perfecting MEMS structures that are stable when released. Patenting these designs will prevent other from copying Nanusens’ breakthrough of MEMS-within-CMOS.

 

The MEMS structures that Nanusens create are ten times smaller than current MEMS structures effectively taking them from the microscopic realm into the nanoscale making them NEMS (Nano Electro Mechanical Systems). One of these NEMS motion sensor structures measures only 100 by 150 microns and takes up less than ten percent of the chip area with the rest being the control electronics.