Lithography

In LELE (litho-etch-litho-etch) double patterning, what is especially strictly required?

  1. AResist color
  2. BThe number of exposure tools
  3. COverlay accuracy between the first and second patterns
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Answer: C. Overlay accuracy between the first and second patterns

In LELE, fine patterns are split in two and exposed and etched separately, so any misalignment of the second pattern relative to the first directly changes the spacing between patterns. Very high overlay accuracy is therefore required. SADP, which uses spacers, is self-aligned, so this problem is smaller.

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