Claims
- 1. An optical scanning system for detection of anomalies, such as particles or pattern defects, on a surface comprising:
means for directing a focused beam of light onto a sample surface to produce an illuminated spot thereon; means for scanning the spot across the surface along a first scan line; a first detector positioned adjacent to said surface to collect scattered light from the spot, wherein the detector includes a linear or two-dimensional array of sensors; and means for focusing scattered light from the illuminated spot at each of a plurality of positions along the scan line onto a corresponding sensor in the array.
- 2. The system of claim 1, said detector positioned to detect light scattered from the spot around a normal direction to the surface.
- 3. The system of claim 1, said detector including a two-dimensional array of sensors that includes at least a first line of sensors, wherein said focusing means focuses light scattered from the spot at said plurality of positions along the first scan line onto the first line of the sensors in the array.
- 4. The system of claim 3, said array further including at least a second line of sensors, wherein said means for scanning scans the spot along at least a second scan line adjacent to the first scan line after scanning the spot along the first scan line, said system further comprising means for synchronizing a transfer of signals from said first line of sensors to the at least one second line of sensors, said focusing means focusing light scattered from the spot at a plurality of positions along the at least second scan line onto said at least one second line of sensors, thereby performing time delayed integration of signals at the array.
- 5. The system of claim 4, further comprising means for controlling scan speed of the scanning means and said synchronizing means to enable said time delay integration.
- 6. The system of claim 5, said scanning means including an acoustic-optic deflector having a chirp rate, said controlling means controlling the chirp rate and timing of the transfer of signals by the synchronizing means.
- 7. The system of claim 4, wherein said focusing means focuses light scattered from only a portion of the spot onto a corresponding sensor.
- 8. The system of claim 7, wherein said plurality of positions of the spot along the second scan line overlaps those along the first scan line.
- 9. The system of claim 8, wherein said portion is about {fraction (1/16)} of the spot and said plurality of positions of the spot along the second scan line overlaps about ¼ of those along the first scan line.
- 10. The system of claim 1, wherein said spot has a spot size whose minimum dimension is in the range of about 2 to 25 microns.
- 11. The system of claim 1, wherein said scanning means scans the spot along a serpentine scan path, said path including a plurality of arrays of scan path segments, wherein each of at least some of such scan path segments has a span shorter than the dimensions of the surface, said scan path segments having lengths in the range of about 2 to 25 mm.
- 12. The system of claim 1, further comprising a first group of detectors oriented to receive light scattered in a direction less than 30 degrees above the surface and symmetrically disposed on opposite sides of the scanning beam at an azimuthal angle of 75 to 105 degrees, with respect to the scanning beam.
- 13. The system of claim 12, further comprising a second group of detectors oriented to receive light scattered in a direction less than 30 degrees above the surface and symmetrically disposed on opposite sides of the scanning beam at an azimuthal angle of 30 to 60 degrees, with respect to the scanning system.
- 14. The system of claim 1, further including an autoposition detector for collecting specularly reflected light from the spot, the autoposition detector having a means for measuring a change in height of the surface.
- 15. The system of claim 1, further comprising:
a group of a plurality of detectors symmetrically positioned about the surface, to collect forwardly and/or laterally scattered light, each of the plurality of detectors producing a signal representing scattered light; means for producing a plurality of maps from said signals and from an output of said first detector; and means for comparing at least two of the maps for identifying anomalies.
- 16. The system of claim 15, said comparing means providing an AND map that comprises only of anomalies present in said at least two of the maps.
- 17. The system of claim 15, said comparing means providing a union map that comprises of anomalies present in either one of said at least two of the maps.
- 18. The system of claim 15, said comparing means providing a XOR map that comprises only of anomalies present in only one but not both of said at least two of the maps.
- 19. The system of claim 15, said comparing means comparing at least two of the maps for identifying pattern defects and particles.
- 20. The system of claim 1, said directing means directing said focused beam at a grazing angle of incidence onto the sample surface.
- 21. An optical scanning method for detection of anomalies, such as particles and pattern defects, on a surface, comprising the steps of:
directing a focused beam of light onto a sample surface to produce an illuminated spot thereon; scanning the spot across the surface along a first scan line; positioning a first detector adjacent to said surface to collect scattered light from the spot, wherein the detector includes a one-dimensional or two-dimensional array of sensors; and focusing scattered light from the illuminated spot at each position along the scan line onto a corresponding sensor in the array.
- 22. The method of claim 21, said positioning step positioning the detector to detect light scattered from the spot around a normal direction to the surface.
- 23. The method of claim 21, said first detector including a two-dimensional array of sensors that includes at least a first line of sensors, wherein said focusing step focuses light scattered from the spot at positions along the first scan line onto a first line of the sensors in the array.
- 24. The method of claim 23, said array further including at least a second line of sensors, wherein said step for scanning scans the spot along at least a second scan line adjacent to the first scan line after scanning the spot along the first scan line, said method further comprising synchronizing a transfer of signals from said first line of sensors to the second line of sensors, said focusing step focusing light scattered from the spot along the at least second scan line onto said second line of sensors, thereby performing time delayed integration of signals at the array.
- 25. The system of claim 24, further comprising controlling scan speed of the scanning step and timing of the transfer of signals in the synchronizing step to enable said time delay integration.
- 26. The system of claim 25, said scanning step employing an acoustic-optic deflector having a chirp rate, said controlling step controlling the chirp rate and timing of the transfer of signals in the synchronizing step.
- 27. The method of claim 24, wherein said focusing step focuses light scattered from only a portion of the spot onto a corresponding sensor.
- 28. The method of claim 27, wherein positions of the spot along the second scan line overlaps those along the first scan line.
- 29. The method of claim 28, wherein said portion is about {fraction (1/16)} of the spot and positions of the spot along the second scan line overlaps about ¼ of those along the first scan line.
- 30. The method of claim 21, wherein said spot has a spot size whose minimum dimension is in the range of about 2 to 25 microns.
- 31. The method of claim 21, wherein said scanning step scans the spot along a serpentine scan path, said path including a plurality of arrays of scan path segments, wherein each of at least some of such scan path segments has a span shorter than the dimensions of the surface, said scan path segments having lengths in the range of about 2 to 25 mm.
- 32. The method of claim 21, further comprising a first group of detectors oriented to receive light scattered in a direction less than 30 degrees above the surface and symmetrically disposed on opposite sides of the scanning beam at an azimuthal angle of 75 to 105 degrees, with respect to the scanning beam.
- 33. The method of claim 21, further comprising:
positioning a group of a plurality of detectors symmetrically positioned about the surface, to collect forwardly and/or laterally scattered light, each of the plurality of detectors producing a signal representing scattered light; producing a plurality of maps from said signals and from an output of the first detector; and comparing at least two of the maps for identifying anomalies.
- 34. The method of claim 33, said comparing step providing an AND map that comprises only of anomalies present in said at least two of the maps.
- 35. The method of claim 33, said comparing step providing a union map that comprises of anomalies present in either one of said at least two of the maps.
- 36. The method of claim 33, said comparing step providing a XOR map that comprises only of anomalies present in only one but not both of said at least two of the maps.
- 37. The method of claim 33, said comparing step comparing at least two of the maps for identifying pattern defects and particles.
- 38. The method of claim 21, said directing step directing said focused beam at a grazing angle of incidence onto the sample surface.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation-in-part application of provisional patent application Serial No. 60/018,973, filed Jun. 4, 1996.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60018973 |
Jun 1996 |
US |
Continuations (2)
|
Number |
Date |
Country |
Parent |
09571303 |
May 2000 |
US |
Child |
10411646 |
Apr 2003 |
US |
Parent |
08868292 |
Jun 1997 |
US |
Child |
09571303 |
May 2000 |
US |