Substrate inspection

1. A system configured to inspect a substrate, comprising:

an illumination subsystem configured to direct light to the substrate, wherein patterned features are formed on an upper surface of the substrate;

an objective configured to collect light scattered from the substrate;

an optical element positioned in a path of the light collected by the objective, wherein the optical element is configured to direct light scattered from the patterned features into a first direction and other scattered light into a second direction;

a detector configured to generate output responsive to only the light directed into the second direction;

an additional detector configured to generate output responsive to only the light directed into the first direction; and

a processor configured to detect defects on the substrate using the output, wherein the processor is further configured to use the output generated by the additional detector to determine diffraction from the patterned features and to adjust the optical element based on the diffraction to direct substantially all of the light scattered from the patterned features into the first direction and to direct any other undesirable scattered light into the first direction.

2. The system of claim 1 , wherein the optical element is a micro mirror array.

3. The system of claim 1 , wherein the optical element is a static optical element.

4. The system of claim 1 , wherein the substrate is transparent, wherein the patterned features are formed on the upper surface after the upper surface is polished, wherein a bottom surface of the substrate is not polished, and wherein a transparent material is formed on the patterned features and the upper surface.

5. The system of claim 4 , further comprising a spatial filter positioned in a path of the other scattered light, wherein the spatial filter is configured to block light scattered from the bottom surface of the substrate and to transmit light scattered from an upper surface of the transparent material, the upper surface of the substrate, and defects on or in the transparent material and between the transparent material and the upper surface of the substrate.

6. The system of claim 4 , wherein the defects detected by the processor comprise defects on or in the transparent material and defects between the transparent material and the upper surface of the substrate and do not include defects on the bottom surface of the substrate.

7. The system of claim 1 , wherein the substrate is transparent, wherein the patterned features are formed on the upper surface after the upper surface is polished, and wherein a bottom surface of the substrate is not polished.

8. The system of claim 7 , further comprising a spatial filter positioned in a path of the other scattered light, wherein the spatial filter is configured to block light scattered from the bottom surface of the substrate and to transmit light scattered from the upper surface of the substrate and any defects on the upper surface of the substrate.

9. The system of claim 7 , wherein the defects detected by the processor comprise defects on the upper surface of the substrate and do not include defects on the bottom surface of the substrate.

10. The system of claim 1 , wherein the substrate is opaque, and wherein the defects detected by the processor comprise defects on the upper surface of the substrate.

11. The system of claim 1 , wherein the substrate is opaque with transparent material formed on the substrate, and wherein the defects detected by the processor comprise defects on or in the transparent material and defects between the transparent material and the upper surface of the opaque substrate.

12. The system of claim 1 , wherein the processor is further configured to use the output generated by the additional detector to detect defects in the patterned features.

13. The system of claim 1 , wherein the processor is further configured to simultaneously detect the defects on the substrate using the output and use the output generated by the additional detector to detect defects in the patterned features.

14. The system of claim 1 , wherein the processor is further configured to use the output generated by the additional detector to determine one or more characteristics of the patterned features.

15. The system of claim 1 , wherein the light directed to the substrate comprises tight having first and second discrete wavelengths, wherein the first and second discrete wavelengths are directed to the substrate simultaneously at the same or different angles of incidences, wherein the system further comprises a beam splitter configured to separate the other scattered light into first scattered light having the first wavelength and second scattered light having the second wavelength, and wherein the system is configured such that the first and second scattered light is directed to different detectors simultaneously.

16. The system of claim 1 , wherein the system is further configured to inspect another substrate, wherein patterned features are not formed on the other substrate, and wherein during inspection of the other substrate, the optical element is configured to direct all of the collected scattered light into the second direction.

17. The system of claim 1 , wherein the system is further configured to inspect another substrate, wherein patterned features are not formed on the other substrate, wherein during review of defects detected on the other substrate, the optical element is configured to direct only a portion of the collected light into the first direction such that different portions of a differential scattering cross-section from a defect are sampled sequentially by the additional detector, and wherein the processor is further configured to use information about the differential scattering cross-section to classify the detected defect.

18. The system of claim 1 , wherein the system is further configured to inspect another substrate, wherein patterned features are not formed on the other substrate, wherein the system further comprises an additional detector array, wherein the system is further configured to replace the optical element with the additional detector array during review of defects detected on the other substrate such that different portions of a differential scattering cross-section from a defect are sampled by the additional detector array, and wherein the processor is further configured to use information about the differential scattering cross-section to classify the detected defect.

19. A system configured to inspect a substrate, comprising:

an illumination subsystem configured to direct light to the substrate, wherein patterned features are formed on an upper surface of the substrate;

an objective configured to collect light scattered from the substrate;

an optical element positioned in a path of the light collected by the objective, wherein the optical element is configured to direct light scattered from the patterned features into a first direction and other scattered light into a second direction;

a first detector configured to generate output responsive to only the light directed into the second direction;

a second detector configured to generate output responsive to only the light directed into the first direction; and

a processor configured to detect defects in the patterned features or to determine one or more characteristics of the patterned features using the output generated by the second detector, wherein the processor is further configured to use the output generated by the second detector to determine diffraction from the patterned features and to adjust the optical element based on the diffraction to direct substantially all of the light scattered from the attuned features into the first direction and to direct any other undesirable scattered light into the first direction.

20. The system of claim 19 , wherein transparent material is formed on the patterned features and the upper surface of the substrate.

21. The system of claim 19 , wherein the system is further configured to replace the optical element with an additional detector array to determine one or more characteristics of the patterned features using the output generated by the additional detector array.

22. The system of claim 19 , wherein the optical element is further configured to direct only a portion of the collected light into the first direction such that different portions of a differential scattering cross-section from a pattern defect are sampled sequentially by the second detector, and wherein the processor is further configured to use information about the differential scattering cross-section to determine one or more characteristics of the pattern defect.

23. The system of claim 19 , wherein the system is further configured to replace the optical element with an additional detector array such that different portions of a differential scattering cross-section from a pattern defect can are sampled by the additional detector array, and wherein the processor is further configured to use information about the differential scattering cross-section to determine one or more characteristics of the pattern defect.

24. A system configured to inspect a substrate, comprising:

an illumination subsystem configured to direct light to the substrate, wherein patterned features are not formed on an upper surface of the substrate;

an objective configured to collect light scattered from the substrate;

an optical element positioned in a path of the light collected by the objective, wherein the optical element is configured to selectively direct the collected light into a first direction or a second direction;

a detector configured to generate output responsive to only the light directed into the second direction; and

a processor configured to detect defects on the substrate using the output, wherein during inspection of the substrate, the optical element is configured to direct all of the collected light into the second direction, wherein during review of defects detected on the substrate, the substrate is stationary with respect to the system such that a differential scattering cross-section from a defect is sampled multiple times sequentially.

25. The system of claim 24 , further comprising an additional detector configured to detect the light directed into the first direction, wherein during the review of defects detected on the substrate, the optical element is configured to direct only a portion of the collected light into the first direction such that different portions of the differential scattering cross-section from the defect are sampled sequentially by the additional detector, and wherein the processor is further configured to use information about the differential scattering cross-section to classify the detected defect.

26. The system of claim 24 , further comprising an additional detector array, wherein the system is further configured to replace the optical element with the additional detector array during the review of defects detected on the substrate such that different portions of the differential scattering cross-section from the defect are sampled by the additional detector array, and wherein the processor is further configured to use information about the differential scattering cross-section to classify the detected defect.