Programmable aperture for lithographic imaging systems

• US 20040197672A1
• Filed: 04/01/2003
• Published: 10/07/2004
• Est. Priority Date: 04/01/2003
• Status: Abandoned Application

• Current Assignee: Synopsys Incorporated
• Original Assignee: Numerical Technologies Inc. (Synopsys Incorporated)
• Inventors: Chang, Fang-Cheng, Weed, J. Tracy
• Application Number:
  US10/405,228
• Publication Number:
  US 20040197672A1
• Time in Patent Office: Days
• US Class Current: 430/5
• CPC Class Codes: G03F 7/70091 Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
• CPC Class Codes: G03F 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/70125 Use of illumination settings tailored to particular mask patterns details of setting means G03F7/70091

Abstract

Printing very small features on a wafer may require optimizing an illumination configuration in the lithographic imaging system. In a conventional system, an aperture provides only one illumination configuration. In contrast, a programmable aperture can ensure that each mask design is printed using its optimized illumination configuration while minimizing the amount of hardware in the system. The programmable aperture can include a grid of pixels, wherein each pixel can be controlled to provided a predetermined light state. Once installed, the programmable aperture can provide any number of illumination configurations, thereby eliminating the expense of fabricating, testing, and repairing multiple apertures as well as the time associated with installing those multiple apertures.

Claims

1. A programmable aperture for a lithographic imaging system, the programmable aperture comprising:

a grid including a plurality of pixels, wherein each pixel can be controlled to provide a predetermined light state.

2. The programmable aperture of claim 1, wherein each pixel provides one of a transmission and an angle of reflectivity.

3. The programmable aperture of claim 1, wherein each pixel is implemented by a liquid crystal cell.

4. The programmable aperture of claim 1, wherein each pixel is implemented by a digital micro-mirror device.

5. The programmable aperture of claim 1, wherein each pixel is implemented by an electro-mechanical device.

6. The programmable aperture of claim 1, wherein the plurality of pixels are programmable to compensate for lens aberrations.

7. The programmable aperture of claim 1, wherein the plurality of pixels are programmable during a wafer exposure.

8. A lithographic imaging system comprising:

a light source for exposing a wafer;

a grid for receiving light from the light source, the grid including a plurality of pixels for providing a plurality of illumination configurations;

a condenser lens for projecting light from the grid onto a mask; and

a projection lens for capturing light from the mask and then focusing the light onto the wafer.

9. The lithographic imaging system of claim 8, wherein each pixel can be controlled to provide a predetermined light state.

10. The lithographic imaging system of claim 8, wherein each pixel provides one of a transmission and an angle of reflectivity.

11. The lithographic imaging system of claim 8, wherein each pixel is implemented by a liquid crystal cell.

12. The lithographic imaging system of claim 8, wherein each pixel is implemented by a digital micro-mirror device.

13. The lithographic imaging system of claim 8, wherein each pixel is implemented by an electro-mechanical device.

14. The lithographic imaging system of claim 8, wherein the plurality of pixels are programmable to compensate for lens aberrations.

15. The lithographic imaging system of claim 8, wherein the plurality of pixels are programmable during a wafer exposure.

16. A lithographic imaging system comprising:

illumination means for exposing a wafer;

programmable means for receiving light from the light source and providing a plurality of illumination configurations;

means for projecting light from the aperture onto a mask; and

means for capturing light from the mask and then focusing the light onto the wafer.

17. The lithographic imaging system of claim 16, wherein the programmable means includes a plurality of pixels, and wherein each pixel can be controlled to provide a predetermined light state.

18. The lithographic imaging system of claim 16, wherein the programmable means includes a plurality of pixels, and wherein each pixel provides one of a transmission and an angle of reflectivity.

19. The lithographic imaging system of claim 16, wherein the programmable means includes a plurality of pixels, and wherein each pixel is implemented by a liquid crystal cell.

20. The lithographic imaging system of claim 16, wherein the programmable means includes a plurality of pixels, and wherein each pixel is implemented by a digital micro-mirror device.

21. The lithographic imaging system of claim 16, wherein the programmable means includes a plurality of pixels, and wherein each pixel is implemented by an electro-mechanical device.

22. The lithographic imaging system of claim 16, wherein the programmable means includes a plurality of pixels, and wherein the plurality of pixels are programmable to compensate for lens aberrations.

23. The lithographic imaging system of claim 16, wherein the programmable means includes a plurality of pixels, and wherein the plurality of pixels are programmable during a wafer exposure.

24. A method of printing a wafer, the method comprising:

generating radiation from a light source;

receiving light from the light source;

programmably providing a plurality of illumination configurations using the light;

projecting a predetermined illumination configuration onto each mask used in printing the wafer; and

capturing light from each mask and focusing the light onto the wafer.

25. The method of claim 24, wherein programmably providing includes controlling individual pixels to provide predetermined light states.

26. The method of claim 25, wherein the predetermined light states are provided by one of transmission and angle of reflectivity.

27. The method of claim 25, wherein the predetermined light states are implemented by liquid crystal cells.

28. The method of claim 25, wherein the predetermined light states are implemented by digital micro-mirror devices.

29. The method of claim 25, wherein the predetermined light states are implemented by an electro-mechanical device.

30. The method of claim 24, wherein programmably providing includes compensating for lens aberrations.

31. The method of claim 24, wherein programmably providing includes changing the illumination configuration during a wafer exposure.

32. The method of claim 31, wherein changing the illumination configuration is performed after using a first mask for printing the wafer and before another mask.

33. The method of claim 24, wherein programmably providing includes creating the plurality of illumination configurations using diffraction pattern matching.

34. A method of implementing an aperture for a lithographic imaging system, the method comprising:

controlling a plurality of pixels to provide predetermined light states.

35. The method of claim 34, wherein controlling the plurality of pixels includes providing voltage to predetermined liquid crystal cells.

36. The method of claim 34, wherein controlling the plurality of pixels includes tilting digital micro-mirror devices at predetermined angles.

37. The method of claim 34, wherein controlling the plurality of pixels includes activating electro-mechanical devices.

38. The method of claim 34, wherein controlling the plurality of pixels includes compensating for lens aberrations.

39. The method of claim 34, wherein controlling the plurality of pixels includes changing the illumination configuration during a wafer exposure.

40. The method of claim 39, wherein changing the illumination configuration is performed after using a first mask for printing the wafer and before a second mask.

41. The method of claim 34, wherein controlling the plurality of pixels includes creating a plurality of illumination configurations using diffraction pattern matching.