MEMS and sensors

When removing an SiO2 sacrificial layer to free a MEMS structure, which method is suitable for preventing stiction?

  1. ARinsing with large amounts of water and letting it dry naturally
  2. BRemoving it by polishing
  3. CVapor-phase etching with hydrogen fluoride (HF) vapor
Show answer and explanation

Answer: C. Vapor-phase etching with hydrogen fluoride (HF) vapor

Removing the sacrificial layer with liquid hydrofluoric acid can cause movable parts to stick to the substrate due to surface tension during drying. Vapor-phase etching with HF vapor uses no liquid, preventing sticking from surface tension. Supercritical CO2 drying is used for the same purpose.

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More MEMS and sensors questions

  1. Which MEMS fabrication method builds movable structures by processing thin films deposited on the substrate?
  2. Which correctly describes how MEMS sensors are combined with their signal-processing circuits?
  3. Why does a MEMS accelerometer detect about 1 G of acceleration even when stationary?
  4. What is the processing called that combines information from accelerometers, gyroscopes, magnetometers and other sensors to determine orientation and motion more accurately?
  5. What is an advantage of MEMS oscillators, sometimes used instead of quartz crystals as clock sources?