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MEMS (micro electro mechanical systems) are tiny mechanical structures in the micrometer range combined with an ASIC (application specific integrated circuit). MEMS at Bosch look back on more than 25 years of development and production and started based on KOH wet‐etching with restrictions in geometry due to the crystal‐oriented etch behavior of KOH. Based on several years of experience in plasma processing and the availability of new prototype plasma sources, the “Bosch Process,” a three‐dimensional plasma etch process for silicon was invented. This is the key enabler for today's huge variety of MEMS products in our every day life.

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Deep Reactive Ion Etching (DRIE) is virtually shaping the MEMS-field. The basic technology originally developed at Bosch is free from the design restrictions and compatibility problems related to the old wet-etching technology which was based on potassium hydroxide (KOH-) solution. The technology has enabled a wide range of new devices like the inertial sensors for acceleration and yaw rate detection, pressure sensors for mid-to high-pressure applications, MEMS microphones, micro-mirrors and quite recently also timing devices fabricated in silicon. These products conquered both the automotive application area, and later on also the consumer field. From the surface-near micromachining of the early development stages, DRIE is nowadays heading towards a true 3D-microstructuring. Pressure sensors, microphones and micromirrors represent first examples of this trend, but also packaging applications like DRIE-structured silicon caps, functionalized silicon carrier substrates for intelligent systems-inpackage, and through-silicon vias (TSV's) for chip-stacking and new chip-integration concepts are receiving increasing attention.This paper leads from the early development phase targeting first high-volume products, to the development of advanced highrate etching solutions targeting today's new and challenging product families.