Cleanrooms and equipment

What is the main reason wafers must not be touched with bare hands?

  1. ASodium and other substances in skin oil and sweat contaminate the wafer and degrade device characteristics and reliability
  2. BBody heat melts the wafer
  3. CFingerprints change the wafer's crystal orientation
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Answer: A. Sodium and other substances in skin oil and sweat contaminate the wafer and degrade device characteristics and reliability

Skin oil and sweat contain organic matter and alkali metals such as sodium. Sodium becomes mobile ions in oxide films and shifts transistor threshold voltages, while organics cause defects in film deposition and bonding. Wafers are therefore handled with dedicated gloves, tweezers, transfer robots and the like.

  • A. Correct. Components of skin oil and sweat are contamination sources.
  • B. Body heat does not melt silicon.
  • C. Fingerprints do not change the crystal orientation.
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More Cleanrooms and equipment questions

  1. Which statement about ISO 14644-1 cleanliness classes is correct?
  2. Which type of cleanroom blows clean air from parts of the ceiling and maintains cleanliness by mixing with and diluting the room air? Its cleanliness is lower than with unidirectional flow, but its equipment cost is lower.
  3. Which filter is used to remove airborne molecular contamination (AMC) such as ammonia and organics from cleanroom air?
  4. In cleanroom air conditioning, which unit filters outside air and adjusts its temperature and humidity before supplying it to the recirculating room air?
  5. In a fab's automated material handling system, which automated storage holds FOUPs temporarily until their next process step?