Apparatus and method for breaking up and merging polygons
A method of modifying polygons in a data set mask-less or mask based optical projection lithography includes: 1) mapping the data set to a figure-of-demerit; 2) moving individual polygon edges to decrease the figure-of-demerit; and 3) disrupting the set of polygons to enable a further decrease in the figure-of-demerit, wherein disrupting polygons includes any of the following polygon disruptions: breaking up, merging, or deleting polygons.
1. A method of modifying polygons in a data set, where each polygon in the data set has a plurality of edges, comprising:
mapping the data set to a figure-of-demerit;
moving said edges to reduce said figure-of-demerit; and
disrupting said set of polygons to enable a further reduction of said figure-of-demerit, wherein said step of disrupting includes any of the following: breaking up polygons; merging polygons; deleting polygons.
2. The method of modifying polygons according to claim 1 , further comprising: using the modified polygon set in a mask-less optical projection lithography process.
3. The method of modifying polygons according to claim 1 , further comprising: using the modified polygon set to make a lithography photomask.
4. The method of modifying polygons according to claim 1 , further comprising:
moving edges of disrupted polygons to further reduce said figure-of-demerit after said step of disrupting.
5. The method of modifying polygons according to claim 4 , further comprising:
repeating the last mentioned steps of disrupting and moving.
6. The method of modifying polygons in a data set according to claim 1 , wherein said step of mapping the data set to a figure-of-demerit includes using a computational model of a patterning process which substantially predicts at least one of the following:
a mask writing proximity effect;
a fogging effect in mask writing;
a mask etch effect; an optical imaging effect;
a photoresist blur effect; a photoresist develop effect; and
a wafer etch effect.
7. The method of modifying polygons in a data set according to claim 6 , further comprising: calculating a measure of difference between a pattern predicted by said computational model and a desired target pattern.
8. The method of modifying polygons in a data set according to 7 , wherein said step of calculating a measure of difference between a pattern predicted by said computational model and a desired target pattern is performed for more than one exposure dose.
9. The method of modifying polygons in a data set according to 7 , wherein said step of calculating a measure of difference between a pattern predicted by said computational model and a desired target pattern is performed for more than one defocus value.
10. The method of modifying polygons in a data set according to 7 , wherein said step of calculating a measure of difference between a pattern predicted by said computational model and a desired target pattern is performed for more than one exposure dose and more than one defocus value.
11. The method of modifying polygons in a data set according to claim 6 , further comprising: calculating a measure of image slope.
12. The method of modifying polygons in a data set according to claim 6 , further comprising: calculating a measure of image contrast.
13. The method of modifying polygons in a data set according to claim 6 , further comprising:
calculating a difference in the pattern predicted by said computational model; wherein the difference is in response to a change in the exposure dose.
14. The method of modifying polygons in a data set according to claim 6 , further comprising:
calculating a difference in the pattern predicted by said computational model; wherein the difference is in response to a change in the defocus.
15. The method of modifying polygons in a data set according to claim 6 , further comprising: calculating a difference in the pattern predicted by said computational model wherein the difference is in response to both a change in the exposure dose and a change in the defocus.
16. A method of modifying polygons in a data set according to claim 1 , further comprising: inserting sub-resolution assist features in the data set prior to said step of moving.
17. A method of modifying polygons in a data set according to claim 1 , further comprising: assigning phase shifts to some of the polygons prior to said step of moving.
18. A method of modifying polygons in a mask data set, comprising:
providing a mask layout defined by a plurality of polygon edges;
providing a computational model that predicts a patterning process;
defining a set of design goals; mapping said mask layout to a figure-of-demerit that quantifies how far said mask layout is from satisfying said set of design goals;
reducing said figure-of-demerit iteratively by moving polygon edges; and
merging, deleting, or breaking up polygons.
19. The method of modifying polygons in a mask data set according to claim 18 , wherein said step of reducing is performed by an optimization algorithm.
20. The method of modifying polygons in a mask data set according to claim 19 , wherein a convex optimization process defines said optimization algorithm.
21. The method of modifying polygons in a mask data set according to claim 19 , wherein a simulated annealing process defines said optimization algorithm.
22. The method of modifying polygons in a mask data set according to claim 19 , wherein said optimization algorithm is a genetic algorithm.
23. A method of modifying polygons in a mask data set, comprising:
moving at least one polygon edge in a set of mask layout polygons to reduce a measure of difference between a target pattern and a printed pattern as predicted by a computational model; and
disrupting the integrity of said set of mask layout polygons to further help reduce said measure of difference.
24. The method of modifying polygons in a mask data set according to claim 23 , wherein said step of disrupting includes allowing one or more polygons in said mask layout to merge.
25. The method of modifying polygons in a mask data set according to claim 23 , wherein said step of disrupting includes allowing one or more polygons in said mask layout to become disjointed.
26. The method of modifying polygons in a mask data set according to claim 23 , wherein said step of disrupting includes allowing one or more polygons in said mask layout to break apart to form a larger set of polygons.
27. The method of modifying polygons in a mask data set according to claim 23 , wherein said step of step of disrupting includes allowing one or more polygons in said mask layout to be deleted to form a smaller set of polygons.