Simultaneous photolithographic mask and target optimization
View Patent ↗A mechanism is provided for simultaneous photolithographic mask and target optimization (SMATO). A lithographic simulator generates an image of a mask shape on a wafer thereby forming one or more lithographic contours. A mask and target movement module analytically evaluates a direction for mask and target movement thereby forming a plurality of pairs of mask and target movements. The mask and target movement module identifies a best pair of mask and target movements from the plurality of mask and target movements that minimizes a weighted cost function. A shape adjustment module adjusts at least one of a target shape or the mask shape based on the best pair of mask and target movements.
1. A method, in a data processing system, for simultaneous photolithographic mask and target optimization (SMATO), the method comprising:
generating, by a lithographic simulator, an image of a mask shape on a wafer thereby forming one or more lithographic contours;
analytically evaluating, by a mask and target movement module, a direction for mask and target movement thereby forming a plurality of pairs of mask and target movements;
identifying, by the mask and target movement module, a best pair of mask and target movements from the plurality of mask and target movements that minimizes a weighted cost function; and
adjusting, by a shape adjustment module, at least one of a target shape or the mask shape based on the best pair of mask and target movements.
2. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should move in by a first predetermined distance and the mask shape should move in by a second predetermined distance.
3. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should not move and the mask shape should move in by a second predetermined distance.
4. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should move out by a first predetermined distance and the mask shape should move in by a second predetermined distance.
5. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should move in by a first predetermined distance and the mask shape should not move.
6. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should not move and the mask shape should not move.
7. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should move out by a first predetermined distance and the mask shape should not move.
8. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should move in by a first predetermined distance and the mask shape should move out by a second predetermined distance.
9. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should not move and the mask shape should move out by a second predetermined distance.
10. The method of claim 1 , wherein the best pair of mask and target movements indicates that the target shape should move out by a first predetermined distance and the mask shape should move out by a second predetermined distance.
11. The method of claim 1 , wherein the weighted cost function is:
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wherein (m 0 , n 0 ) is an initial location of a center of a target edge in the target shape, wherein n m is movement in the mask shape, and wherein w i is the weight.
12. The method of claim 11 , wherein the weight w i in the weighted cost function is dynamically tunable at each iteration to improve convergence to a mask and target solution, wherein the dynamic tuning weights either an intensity error higher for a predetermined number of iterations to bring the lithographic contours closer to the target or the intensity slope higher to improve robustness.
13. The method of claim 12 , wherein the analytical evaluation of the intensity error occurs in a pixel-based simulation domain.
14. The method of claim 12 , wherein the analytical evaluation of the intensity slope occurs in a pixel-based simulation domain.
15. The method of claim 12 , wherein the analytical evaluation is sped up by using lookup tables characterized for fragments of different lengths and different amounts of mask movements.
16. The method of claim 12 , wherein the analytical evaluation is sped up by using lookup tables characterized for fragments of different lengths and different amounts of target movements.
17. The method of claim 11 , wherein the weighted cost function is analytically computed by using a SOCS decomposition of a Hopkins equations and obtains the amount of perturbation in terms of the optical kernels.
18. The method of claim 1 , further comprising:
repeating, by the data processing system, the steps of generating, analytically evaluating, identifying, and adjusting a predetermined number of times; and
responsive to the predetermined number of times being met, generating, by the data processing system, a set of clean mask shapes.
19. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to:
generate an image of a mask shape on a wafer thereby forming one or more lithographic contours;
analytically evaluate a direction for mask and target movement thereby forming a plurality of pairs of mask and target movements;
identify a best pair of mask and target movements from the plurality of mask and target movements that minimizes a weighted cost function; and
adjust at least one of a target shape or the mask shape based on the best pair of mask and target movements.
20. An apparatus, comprising:
a processor; and
a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to:
generate an image of a mask shape on a wafer thereby forming one or more lithographic contours;
analytically evaluate a direction for mask and target movement thereby forming a plurality of pairs of mask and target movements;
identify a best pair of mask and target movements from the plurality of mask and target movements that minimizes a weighted cost function; and
adjust at least one of a target shape or the mask shape based on the best pair of mask and target movements.