Lithography

Which correctly describes OPC (optical proximity correction)?

  1. ACoating resist thicker to improve resolution
  2. BCleaning the mask to remove particles
  3. CCorrecting the mask pattern in advance to reduce shape distortion after transfer
Show answer and explanation

Answer: C. Correcting the mask pattern in advance to reduce shape distortion after transfer

For patterns near the resolution limit, diffraction and interference prevent the mask shape from transferring faithfully: line ends shrink and corners round. OPC anticipates these distortions by adding assist features to the mask pattern or adjusting dimensions.

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More Lithography questions

  1. What is the purpose of a phase-shift mask?
  2. What is overlay accuracy in lithography?
  3. Which is a characteristic of chemically amplified resists?
  4. What is the typical reduction ratio when today's exposure tools (scanners) project the mask pattern onto the wafer?
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