Skip to main content
Semiconductors and sensors from Bosch

The success story behind Bosch MEMS sensors

How Bosch invented the MEMS manufacturing standard

MEMS
  • Groundbreaking innovation in silicon etching by Bosch engineers Andrea Urban and Franz Lärmer
  • Patented in 1994, the “DRIE process” became the technological foundation for MEMS sensors by Bosch
  • Today, Bosch produces more than two billion MEMS sensors per year

MEMS sensors are everywhere: in the airbag that protects a driver, in the smartphone that counts steps, in the machine that monitors vibration on a factory floor. Behind nearly all of them lies a single manufacturing breakthrough that Bosch made more than three decades ago – and still relies on today. It is known as the Bosch Process, or by its technical name, Deep Reactive Ion Etching (DRIE). Unlike many technologies that companies license from research institutes or specialized suppliers, Bosch developed this one entirely in-house.

Solving a manufacturing challenge

In the early 1990s, etching deep structures into silicon was nothing new. But it had a persistent flaw: The etching process also worked sideways, eating into the walls of the structures that were being created. In Bosch’s corporate research department, engineers Andrea Urban and her mentor Franz Lärmer set out to solve this challenge. The purpose of their work was to etch deep microstructures with vertical sidewalls into silicon wafers at high speed and with great accuracy.

After just half a year, the Bosch engineers had figured out a new solution by using a fluorocarbon-based plasma to deposit an etch-resistant layer before taking a subsequent etch step. The technique, nowadays simply referred to as the Bosch Process, allows deep etching of trench-like structures in a well-defined manner. In 1992, Andrea Urban and Franz Lärmer filed a patent for this revolutionary manufacturing process. Two years later, the underlying “trench process” patent was granted and it became the technological basis on which Bosch build its entire MEMS sensor business.

franz laermer
"When we developed the process, our main challenge wasn't just making the etching more precise – it was making that precision reliable enough for mass production. This is a continuous process, as precision demand and robustness under production conditions increases with future product generations."
Andrea Urban, Senior Expert Wafer Technology DRIE at Bosch
Andrea Urban

From patent to global standard

The process did not stay in the lab for long. The first MEMS to start leaving the Reutlingen plant in 1995 were pressure sensors for the automotive industry. They were joined by sensors for airbag activation in 1996 and for the electronic stability program (ESP) in 1998. Thanks to the newly patented solution, Bosch could produce complex, high-precision vertical structures in one continuous process on standard silicon wafers at consistent quality.

The innovation also makes it possible to manufacture sensors extremely cost-effectively at high-volumes – making them affordable for entry-level vehicles instead of just premium models. Modern cars contain an average of 27 MEMS sensors, more than eight of them are usually from Bosch. Many are capacitive accelerometers: tiny silicon structures with movable electrodes that shift under acceleration, changing the capacitance between them – a signal used, for example, to detect a crash and trigger the airbag within milliseconds.

MEMS Products

Among the MEMS market leaders

Today, Bosch produces more than two billion MEMS sensors per year. The use of MEMS sensors extends well beyond the automotive sector. MEMS sensors are an essential part of everyday objects such as consumer goods, electrical appliances, healthcare applications such as fitness trackers, and many other devices. Every second new smartphone is already equipped with a MEMS sensor from Bosch. Over the years, Bosch has become one of the world’s leading MEMS manufacturing companies, which has recently been confirmed again in the status report about the MEMS industry by Yole Group, one of the semiconductor industry’s leading market research and strategy firms.

Five good reasons for MEMS from Bosch

  • Decades of experience : With more than 26 billion MEMS sensors produced and over 30 years of experience, Bosch is a pioneer in MEMS sensor technology.
  • Reliable manufacturing : Consistent high quality thanks to Bosch’s proven expertise in semiconductor manufacturing.
  • Precision at scale : Production of large quantities of ultra-precise sensors.
  • Affordability : High-precision safety sensors at a cost that work for every vehicle class – with no compromise on quality.
  • Versatile application : The MEMS manufacturing principle is not only suited for the automotive industry but also for smartphones, laptops, robotics as well as medical and healthcare applications.

This might also be interesting for you