Geometric mask rule check with favorable and unfavorable zones
A method includes generating a diffraction map from a plurality of target patterns, generating a favorable zone and an unfavorable zone from the diffraction map, placing a plurality of sub-resolution patterns in the favorable zone, and performing a plurality of geometric operations on the plurality of sub-resolution patterns to generate modified sub-resolution patterns. The modified sub-resolution patterns extend into the favorable zone, and are away from the unfavorable zone.
1. A method comprising:
generating a diffraction map from target patterns;
generating a first plurality of sub-resolution patterns in the diffraction map;
selecting a first sub-resolution pattern from the first plurality of sub-resolution patterns, wherein the selecting is based on locations of the first plurality of sub-resolution patterns in the diffraction map;
performing a modification operation to modify the first plurality of sub-resolution patterns collectively into a second plurality of sub-resolution patterns, wherein the first sub-resolution pattern is modified to generate a second sub-resolution pattern; and
forming a photolithography mask comprising patterns of the target patterns and the second plurality of sub-resolution patterns.
2. The method of claim 1 further comprising determining a first region in the diffraction map as an unfavorable zone, and the first sub-resolution pattern comprises a portion in the unfavorable zone, and wherein the portion of the first sub-resolution pattern in the unfavorable zone is removed to form the second sub-resolution pattern.
3. The method of claim 2 , wherein the selecting the first sub-resolution pattern comprises finding one of the first plurality of sub-resolution patterns that extends into the unfavorable zone.
4. The method of claim 2 further comprising determining a second region in the diffraction map as a favorable zone, wherein the first plurality of sub-resolution patterns are generated at least partially in the favorable zone.
5. The method of claim 4 , wherein both of the favorable zone and the unfavorable zone are ring-shaped zones, and the unfavorable zone encircles the favorable zone.
6. The method of claim 4 , wherein the diffraction map comprises a bright zone and a dark zone, and wherein a first part of the bright zone is determined to be the favorable zone, and a second part of the dark zone is determined to be the unfavorable zone.
7. The method of claim 1 , wherein the first plurality of sub-resolution patterns further comprise a second sub-resolution pattern, and wherein both of the first plurality of sub-resolution patterns and the second plurality of sub-resolution patterns comprise the second sub-resolution pattern.
8. The method of claim 7 , wherein the second sub-resolution pattern in the first plurality of sub-resolution patterns is identical to the second sub-resolution pattern in the second plurality of sub-resolution patterns.
9. The method of claim 1 further comprising, before the first plurality of sub-resolution patterns are generated:
generating a third plurality of sub-resolution patterns in the diffraction map;
performing a mask rule check process on the third plurality of sub-resolution patterns; and
modifying the third plurality of sub-resolution patterns based on results of the mask rule check process to generate the first plurality of sub-resolution patterns.
10. The method of claim 1 , wherein the modification operation comprises an operation selected from the group consisting of shrinking, relocation, merging, and combinations thereof.
11. The method of claim 10 , wherein the modification operation comprises merging two of the first plurality of sub-resolution patterns.
12. The method of claim 1 , wherein the modification operation further comprises removing an additional sub-resolution pattern from the first plurality of sub-resolution patterns.
13. A method comprising:
generating a diffraction map from a plurality of target patterns;
determining a favorable zone and an unfavorable zone in the diffraction map, wherein the unfavorable zone encircles the favorable zone;
placing a plurality of sub-resolution patterns in the favorable zone;
selecting a first sub-resolution pattern from the plurality of sub-resolution patterns, wherein the first sub-resolution pattern is selected based on a location of the first sub-resolution pattern in the diffraction map;
modifying a pattern of the first sub-resolution pattern to generate a modified sub-resolution pattern, wherein the modified sub-resolution pattern is generated based on a second location of the modified sub-resolution pattern; and
implementing the plurality of target patterns on a semiconductor wafer.
14. The method of claim 13 further comprising forming the modified sub-resolution pattern and the plurality of target patterns in a lithography mask.
15. The method of claim 14 , wherein a second sub-resolution pattern in the lithography mask has an identical pattern as in the plurality of sub-resolution patterns that are placed in the favorable zone.
16. The method of claim 13 further comprising:
after the pattern of the first sub-resolution pattern is modified, performing a mask rule check process on the first sub-resolution pattern.
17. The method of claim 13 further comprising modifying the modified sub-resolution pattern.
18. A method comprising:
generating a diffraction map from a target pattern;
generating a first scattering pattern in the diffraction map;
performing a first modification process, wherein the first scattering pattern is modified to generate a modified scattering pattern;
after the first modification process, selecting the modified scattering pattern and performing a second modification process to modify the modified scattering pattern and to generate a re-modified scattering pattern, wherein the modified scattering pattern is selected based on a position of the modified scattering pattern in the diffraction map; and
forming a photo lithography mask comprising both of the re-modified scattering pattern and the target pattern.
19. The method of claim 18 further comprising determining an unfavorable zone and a favorable zone from the diffraction map, wherein the modified scattering pattern is selected based on a portion of the modified scattering pattern being in the unfavorable zone.
20. The method of claim 19 , wherein the portion of the modified scattering pattern in the unfavorable zone is removed to form the re-modified scattering pattern.