Method and system of lithography using masks having gray-tone features
A method forms patterns on a substrate by exposing the substrate a first time and exposing the substrate a second time using a mask containing gray-tone features. The gray-tone features locally adjust an exposure dose in regions corresponding to features defined in the primary exposure. Moreover, the gray-tone features enable the forming of features having different critical dimensions on a substrate. The gray-tone features may be sub-resolution features and formed by pixellation. The trim mask containing gray-tone features may have regions with different transmissivities.
1. A computer aided design method for designing a mask, comprising:
(a) specifying, through an input of a user, a geometric property of a desired substrate feature; and
(b) determining automatically, based upon the user specified geometric property of the desired substrate feature, mask features for a gray-tone mask.
2. The computer aided design method as claimed in claim 1 , wherein the determined mask features correspond to mask features on a phase shift mask.
3. The computer aided design method as claimed in claim 1 , wherein the determined mask features correspond to mask features on a binary mask.
4. The computer aided design method as claimed in claim 2 , wherein some of the determined mask features on the phase shift mask are gray-tone features.
5. The computer aided design method as claimed in claim 4 , wherein the gray-tone features are regions of varying transmissivity.
6. The computer aided design method as claimed in claim 4 , wherein the gray-tone features are pixellated regions.
7. The computer aided design method as claimed in claim 4 , wherein the gray-tone features are sub-resolution features.
8. The computer aided design method as claimed in claim 1 , wherein the mask features are regions of various transmissivities.
9. The computer aided design method as claimed in claim 1 , wherein the mask features are pixellated regions.
10. The computer aided design method as claimed in claim 1 , wherein the mask features are sub-resolution features.
11. The computer aided design method as claimed in claim 1 , wherein the mask features are derived in an automated manner using an optical simulation engine.
12. The computer aided design method as claimed in claim 1 , wherein the mask features are derived in an automated manner using geometry-based rules.
13. The computer aided design method as claimed in claim 1 , wherein a template is utilized in feature placement.
14. The computer aided design method as claimed in claim 4 , wherein the mask features are derived in an automated manner using an optical simulation engine.
15. The computer aided design method as claimed in claim 4 , wherein the mask features are derived in an automated manner using geometry-based rules.
16. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a critical dimension of the desired substrate feature.
17. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a location of the desired substrate feature.
18. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is orientation of the desired substrate feature.
19. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a spatial representation in two dimensions of the desired substrate feature.
20. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a spatial representation in three dimensions of the desired substrate feature.
21. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a width dimension of the desired substrate feature.
22. The computer aided design method as claimed in claim 1 wherein the desired geometric property is a length dimension of the desired substrate feature.
23. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a thickness dimension of the desired substrate feature.
24. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a sidewall angle of the desired substrate feature.
25. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a curvature of the desired substrate feature.
26. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is a taper of the desired substrate feature.
27. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is input by the user using an input/output device.
28. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is input by the user using a data file.
29. The computer aided design method as claimed in claim 1 , wherein the desired geometric property is input by the user using a data stream.