MEMS and sensors

What is the purpose of sacrificial-layer etching in MEMS fabrication?

  1. ATo thin and lighten the wafer
  2. BTo reduce wiring resistance
  3. CTo remove the layer under a structure so the movable part floats free of the substrate
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Answer: C. To remove the layer under a structure so the movable part floats free of the substrate

In sacrificial-layer etching, the structural film is built on a layer meant to be removed later (the sacrificial layer, such as SiO2), and finally only the sacrificial layer is selectively etched away. This creates movable structures such as beams and membranes suspended above the substrate.

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