Metrology and analysis

Which method is used to measure wafer bow, warp and flatness?

  1. ANoncontact shape measurement with optical interferometers or capacitance sensors
  2. BMass analysis by SIMS
  3. CElemental analysis by EDX
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Answer: A. Noncontact shape measurement with optical interferometers or capacitance sensors

Wafer shape is measured without contact, using instruments based on optical interference or sensors that measure the distance to both sides of the wafer by capacitance. Bow and flatness affect exposure focus and wafer handling and chucking, so they are controlled in incoming wafer inspection and after deposition.

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More Metrology and analysis questions

  1. Which technique evaluates whether a measuring instrument's repeatability and reproducibility are small enough compared with the process variation to be controlled?
  2. What is the main reason fine patterns a few tens of nm wide cannot be observed directly with an optical microscope?
  3. Which equation is used to determine film stress from the change in wafer bow before and after deposition?
  4. Whereas SIMS measures the atomic concentration of impurities, which method measures the depth distribution of electrically active carrier concentration?
  5. What is the measurement called that monitors a process by measuring product wafers partway through processing on the production line?