Method and system for measuring thin films

1. A method for use in measurements of thin films, the method comprising illuminating a plurality of measurement sites in a semiconductor workpiece and detecting light responses of the measurement sites, wherein the plurality of measurement sites defines an array of substantially concentric ring-like regions such that an area defined by the measurement sites within one of the substantially concentric ring-like regions is substantially equal to that of the other substantially concentric ring-like region, and measuring thin film parameters of said workpiece in the measurement sites within one of the substantially concentric ring-like regions.

2. The method according to claim 1 , wherein said array of substantially concentric ring-like regions is created by applying substantially concentric ring-like optical fiber bundles to the workpiece, the ring-like fiber bundles having different radii and widths.

3. The method according to claim 1 , wherein said array of substantially concentric ring-like regions is created by creating an illuminating spot on the workpiece and scanning the workpiece with the illuminating spot while rotating the workpiece with a predetermined velocity and providing a relative displacement between the workpiece and the illuminating spot along a radius of the workpiece.

4. The method according to claim 3 , wherein a velocity of said displacement between the workpiece and the illuminating spot decreases from the center of the workpiece towards the edge.

5. The method according to claim 3 , wherein a velocity of said displacement between the workpiece and the illuminating spot along a radius of the workpiece is substantially constant and the size of the illuminating spot is variable.

6. The method according to claim 5 , wherein said illuminating spot has a slit-like shape.

7. The method according to claim 1 , wherein said illumination is substantially normal to a surface of the workpiece.

8. The method according to claim 7 , wherein said illumination uses polarized light.

9. The method according to claim 1 , wherein said illumination is oblique to a surface of the workpiece.

10. The method according to claim 9 , wherein said illumination uses polarized light.

11. The method according to claim 1 , wherein said detecting of light responses is performed by a spectrophotometer.

12. A method for use in measurements of a wafer's top layer radial thickness distribution, the method comprising illuminating a plurality of measurement sites in a wafer workpiece and detecting light responses of the measurement sites, wherein the plurality of measurement sites define an array of substantially concentric ring-like regions such that an area defined by the measurement sites within one of the substantially concentric ring-like regions is substantially equal to that of the other substantially concentric ring-like region, and measuring a top layer radial thickness distribution of said workpiece in the measurement sites within one of the substantially concentric ring-like regions.

13. The method according to claim 12 , wherein said array of substantially concentric ring-like regions is created by substantially concentric ring-like optical fiber bundles applied to the workpiece, the ring-like fiber bundles having different radii and widths.

14. The method according to claim 12 , wherein said array of substantially concentric ring-like regions is created by creating an illuminating spot on the workpiece and scanning the workpiece with the illuminating spot while rotating the workpiece with a predetermined velocity and providing a relative displacement between the workpiece and the illuminating spot along a radius of the workpiece.

15. The method according to claim 12 , wherein said illumination is substantially normal to a surface of the workpiece.

16. The method according to claim 15 , wherein said illumination uses polarized light.

17. The method according to claim 12 , wherein said illumination is oblique to a surface of the workpiece.

18. The method according to claim 17 , wherein said illumination uses polarized light.

19. The method according to claim 12 , wherein said detecting of light responses is performed by a spectrophotometer.

20. An optical system for use in measurements of thin films of a workpiece, the system comprising an illuminator assembly, a detector assembly, and a light directing assembly for directing illuminating light to a plurality of measurement sites in the workpiece arranged in an array of substantially concentric ring-like regions, such that an area defined by the measurement sites within one of the substantially concentric ring-like regions is substantially equal to that of the other substantially concentric ring-like region.

21. The system according to claim 20 , wherein said light directing assembly is formed by a plurality of fiber-optic bundles, each ended by ring-like optical fixtures.

22. The system according to claim 21 , further comprising a light distribution assembly.

23. The system according to claim 22 , wherein said light distribution assembly comprises a rotatable mirror.

24. The system according to claim 21 , wherein said fiber-optic bundles have substantially equal cross-sections.

25. The system according to claim 21 , wherein said fiber-optic bundles are formed by substantially equal numbers of optical fibers with substantially equal cross-sections.

26. The system according to claim 20 , wherein said detector assembly comprises a spectrophotometer.

27. The system according to claim 20 , further comprising a polarizer in the light directing assembly.

28. An optical measurement system for measurements of thin films of a workpiece, the system comprising a handler for handling the workpiece, illuminator assembly, a detector assembly, and a light directing assembly for directing illuminating light to a plurality of measurement sites in the workpiece arranged in an array of substantially concentric ring-like regions, such that an area defined by the measurement sites within one of the substantially concentric ring-like regions is substantially equal to that of the other substantially concentric ring-like region.

29. The system according to claim 28 , wherein said handler is rotatable and movable along a horizontal axis.

30. The system according to claim 28 , wherein said handler is rotatable and said light directing assembly is movable along a horizontal axis.