Geometric mask rule check with favorable and unfavorable zones

1. A method comprising:

generating a diffraction map from a target pattern, wherein the diffraction map comprises a bright pattern and a dark pattern;

generating a favorable zone and an unfavorable zone from the bright pattern and the dark pattern;

placing a first plurality of sub-resolution patterns in the favorable zone;

performing a mask-rule compliant operation on the first plurality of sub-resolution patterns to generate a second plurality of sub-resolution patterns, wherein a first group of sub-resolution patterns in the first plurality of sub-resolution patterns are enlarged;

performing an unfavorable zone check process to find unfavorable patterns, wherein the unfavorable patterns are enlarged first group of sub-resolution patterns that extend into the unfavorable zone; and

performing a geometric operation on the second plurality of sub-resolution patterns to generate a third plurality of sub-resolution patterns, wherein unfavorable patterns are separated from the unfavorable zone.

2. The method of claim 1 further comprising a mask rule check process to find the first group of sub-resolution patterns from the first plurality of sub-resolution patterns, wherein the first group of sub-resolution patterns are mask-rule violating patterns.

3. The method of claim 2 , wherein the first plurality of sub-resolution patterns further comprise a second group of sub-resolution patterns that are mask-rule compliant, and in the mask-rule compliant operation, the second group of sub-resolution patterns are un-modified.

4. The method of claim 1 , wherein the mask-rule compliant operation comprises an operation selected from the group consisting of enlargement, relocation, merging the first plurality of sub-resolution patterns.

5. The method of claim 1 , wherein the geometric operation comprises relocating, shrinking, merging, or removing one of the unfavorable patterns.

6. The method of claim 1 , wherein the geometric operation comprises removing one of the unfavorable patterns.

7. The method of claim 1 , wherein the geometric operation comprises merging one of the unfavorable patterns with another one of the second plurality of sub-resolution patterns.

8. The method of claim 1 further comprising:

manufacturing a photo lithography mask, wherein the target pattern and the third plurality of sub-resolution patterns are formed in the photo lithography mask; and

using the photo lithography mask to form an integrated circuit component, wherein the target pattern is implemented on the integrated circuit component, and the third plurality of sub-resolution patterns are not implemented on the integrated circuit component.

9. The method of claim 1 , wherein the unfavorable patterns are found by finding the first plurality of sub-resolution patterns that extend into the unfavorable zone.

10. The method of claim 9 further comprising enlarging additional mask-rule violating scattering bars in the third plurality of sub-resolution patterns to generate a fourth plurality of sub-resolution patterns.

11. The method of claim 10 further comprising performing an additional unfavorable zone check on the fourth plurality of sub-resolution patterns.

12. A method comprising:

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, wherein the modified sub-resolution patterns extend into the favorable zone, and are away from the unfavorable zone.

13. The method of claim 12 , wherein the diffraction map comprises a bright region and a dark region, and the favorable zone comprises a part of the bright region, and the unfavorable zone comprises a part of the dark region.

14. The method of claim 12 further comprising determining a first threshold brightness value and a second threshold brightness value equal to or higher than the first threshold brightness value, wherein regions in the diffraction map with brightness values lower than the first threshold brightness value are in unfavorable zones, and wherein regions in the diffraction map with brightness values higher than the second threshold brightness value are in favorable zones.

15. The method of claim 12 , wherein the plurality of geometric operations comprise:

an enlargement operation to enlarge some of the plurality of sub-resolution patterns and to generate enlarged patterns; and

an additional geometric operation to separate the enlarged patterns from the unfavorable zone.

16. The method of claim 12 further comprising performing a mask rule check process to find mask-rule violating scattering bars in the plurality of sub-resolution patterns that have gone through some of the plurality of geometric operations.

17. The method of claim 12 further comprising an unfavorable zone check process to find unfavorable patterns in the plurality of sub-resolution patterns, wherein the unfavorable patterns extend into the unfavorable zone.

18. A method comprising:

generating an unfavorable zone and a scattering pattern;

determining whether the scattering pattern is overlapped with the unfavorable zone;

modifying the scattering pattern to generate a modified scattering pattern, wherein the modified scattering pattern is separated from the unfavorable zone;

forming a photo lithography mask comprising the modified scattering pattern; and

using the photo lithography mask to perform a light-exposure process on a photo resist.

19. The method of claim 18 further comprising:

generating a diffraction map from a target pattern, wherein the target pattern is also in the photo lithography mask; and

determining the unfavorable zone and a favorable zone from the diffraction map, wherein the scattering pattern is placed in the favorable zone.

20. The method of claim 18 , wherein the modifying the scattering pattern comprises enlarging the scattering pattern.