System and method for lithography process monitoring and control

• US 6,803,554 B2
• Filed: 11/07/2003
• Issued: 10/12/2004
• Est. Priority Date: 06/07/2002
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: Brion Technologies Incorporated (ASML Holding NV)
• Inventors: Ye, Jun, Chen, Xun, Pease, R. Fabian W.
• Primary Examiner(s): Le, Que T.
• Application Number:
  US10/703,732
• Publication Number:
  US 20040119036A1
• Time in Patent Office: 340 Days
• Field of Search: 250/208.1, 250/548, 250/559.4, 250/559.45, 356/399, 356/400, 356/401, 355/53, 355/55, 430/5, 430/21
• US Class Current: 250/208.1
• CPC Class Codes: G03F 7/70591 Testing optical components
• CPC Class Codes: G03F 7/7065 Defects, e.g. optical inspection of patterned layer for defects
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load

Abstract

In one aspect, the present invention is a technique of, and a system and sensor for measuring, inspecting, characterizing and/or evaluating optical lithographic equipment, methods, and/or materials used therewith, for example, photomasks. In one embodiment of this aspect of the invention, the system, sensor and technique measures, collects and/or detects an aerial image produced or generated by the interaction between the photomask and lithographic equipment. An image sensor unit may measure, collect, sense and/or detect the aerial image in situ—that is, the aerial image at the wafer plane produced, in part, by a product-type photomask (i.e., a wafer having integrated circuits formed during the integrated circuit fabrication process) and/or by associated lithographic equipment used, or to be used, to manufacture of integrated circuits.

Claims

1. A mask inspection system to detect defects in a mask used in the manufacture of integrated circuits, wherein the mask includes features having a line width, the system comprising:

an optical system to produce the image of the mask on a wafer plane;

a platform moveable between a plurality of locations in a first direction and a plurality of locations in a second direction;

an image sensor unit disposed on the moveable platform, the image sensor unit includes a sensor array located in the wafer plane, wherein the sensor array includes a plurality of sensor cells wherein each sensor cell includes an active area to sample light of a predetermined wavelength that is incident thereon, and wherein the sensor cells sample the intensity of light at a plurality of locations of the platform;

a first processing unit, coupled to the image sensor unit, to compare data which is representative of the intensity of light sampled by each sensor cell at the plurality of locations of the platform to associated data of a mask pattern design database, wherein the mask pattern design database includes data which is representative of the features on the mask.

2. The system of claim 1 wherein the mask pattern design database is comprised of intensity data.

3. The system of claim 1 wherein the mask pattern design database includes polygon data.

4. The system of claim 3 wherein the first processing unit converts the polygon data to associated intensity data.

5. The system of claim 1 wherein the first processing unit converts the data which is representative of the intensity of light sampled by each sensor cell at the plurality of locations of the platform to associated polygon data and wherein the mask pattern design database is comprised of polygon data.

6. The system of claim 1 further including a second processing unit to convert polygon data of a first design database to the mask pattern design database comprised of intensity data wherein the intensity data for each spatial location corresponds to the polygon data for each associated spatial location.

7. The system of claim 1 wherein the first processing unit generates an aerial image of the mask by interleaving the intensity data sampled by each sensor cell at the plurality of locations of the platform.

8. The system of claim 7 wherein the first processing unit compares the aerial image of the mask with a simulated aerial image of the mask that is generated using the mask pattern design database.

9. The system of claim 1 wherein the image sensor unit further includes:

a substrate wherein the sensor array is disposed on or in the substrate; and

a processor to generate the data which is representative of the intensity of light sampled by each sensor cell at the plurality of locations of the platform.

10. The system of claim 1 wherein the image sensor unit further includes:

a substrate wherein the sensor array is disposed on or in the substrate;

data compression circuitry to generate compressed data using each sample of the intensity of light at each location; and

wherein the first processing unit, receives the compressed data and generates the data which is representative of the intensity of light sampled by each sensor cell at the plurality of locations of the platform.

11. The system of claim 1 wherein the image sensor unit further includes:

a wafer-shaped substrate wherein the sensor array is dispose on or in the substrate;

a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that one aperture of the plurality of apertures overlies a corresponding active area of a corresponding sensor cell to expose a portion of the active area and wherein light of the predetermine wavelength is capable of being sensed by the portion of the active area that is exposed by the corresponding aperture.

12. The system of claim 11 wherein the mask pattern design database is comprised of intensity data.

13. The system of claim 1 wherein the mask includes OPC or PSM features and wherein the mask pattern design database includes data which is representative of the design-target.

14. The system of claim 1 wherein the mask includes OPC or PSM features and wherein the mask pattern design database includes data which is representative of the after-OPC or PSM-decoration pattern.

15. The system of claim 1 wherein the mask includes OPC or PSM features and wherein the mask pattern design database includes data which is representative of the design-target and data which is representative of the after-OPC or PSM-decoration pattern.

16. A mask inspection system to detect defects in a mask used in the manufacture of integrated circuits, wherein the mask includes features having a line width, the system comprising:

an optical system to produce the image of the mask on a wafer plane;

a platform moveable between a plurality of locations along a plurality of axes;

an image sensor unit disposed on or in the moveable platform, the image sensor unit includes a sensor array located in the wafer plane, wherein the sensor array includes a plurality of sensor cells wherein each sensor cell includes an active area to sample light of a predetermined wavelength that is incident thereon, and wherein the sensor cells sample the intensity of light at a plurality of locations of the platform; and

a first processing unit, coupled to the image sensor unit, to compare data which is representative of the intensity of light sampled by each sensor cell at a plurality of locations of a first die to data which is representative of the intensity of light sampled by each sensor cell at a plurality of locations of a second die.

17. The system of claim 16 wherein the image sensor unit further includes:

a substrate having a wafer-shaped profile, wherein the sensor array is disposed on the substrate;

a film, disposed over selected portions of the active areas of the plurality of sensor cells to enhance the spatial resolution of each sensor cell wherein the film is comprised of a material that impedes passage of light of the predetermined wavelength.

18. The system of claim 16 wherein the image sensor unit further includes:

a wafer-shaped substrate, wherein the sensor array is integrated in, or disposed on the substrate;

a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that one aperture of the plurality of apertures overlies a corresponding active area of a corresponding sensor cell to expose a portion of the active area and wherein light of the predetermine wavelength is capable of being sensed by the portion of the active area that is exposed by the corresponding aperture.

19. The system of claim 16 wherein first processing unit further compares data which is representative of the intensity of light sampled by each sensor cell at a plurality of locations of the first die to associated data of a mask pattern design database.

20. The system of claim 19 wherein the mask pattern design database includes polygon data.

21. The system of claim 19 wherein the mask pattern design database is comprised of intensity data.

22. The system of claim 19 further including a second processing unit to convert the polygon data of a first design database to the mask pattern design database comprised of intensity data, wherein the intensity data for each spatial location corresponds to the polygon data for each associated spatial location.

23. The system of claim 22 wherein the mask includes OPC or PSM features and wherein the mask pattern design database includes data which is representative of the design-target.

24. The system of claim 22 wherein the mask includes OPC or PSM features and wherein the mask pattern design database includes data which is representative of the after-OPC or PSM-decoration pattern.

25. The system of claim 22 wherein the mask includes OPC or PSM features and wherein the mask pattern design database includes data which is representative of the design-target and data which is representative of the after-OPC or PSM-decoration pattern.

26. A mask inspection system to detect defects in a mask used in the manufacture of integrated circuits, wherein the mask includes features having a line width, the system comprising:

an optical system to produce the image of the mask on a wafer plane;

a platform moveable between a plurality of locations in a first direction and a plurality of locations in a second direction;

a sensor array disposed above or in the moveable platform and located in the wafer plane, wherein the sensor array includes a plurality of sensor cells wherein each sensor cell includes an active area to sample light of a predetermined wavelength that is incident thereon, and wherein the sensor cells sample the intensity of light at a plurality locations of the platform;

a processing unit, coupled to the sensor array, to compare data which is representative of the intensity of light sampled by each sensor cell at the plurality of locations of the platform to associated data of a mask pattern design database, wherein the mask pattern design database includes data which is representative of the features on the mask.

27. The system of claim 26 wherein the mask pattern design database is a design-target of the wafer image of the mask.

28. The system of claim 26 wherein the mask pattern design database includes polygon data which is representative of the mask.

29. The system of claim 26 wherein the mask pattern design database includes intensity data which is representative of the mask.

30. The system of claim 26 further including a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that one aperture of the plurality of apertures overlies an associated active area of a corresponding sensor cell to expose a portion of the active area and wherein light of the predetermined wavelength is capable of being sensed by the portion of the active area that is exposed by the associated aperture.

31. The system of claim 26 wherein the processing unit converts the data which is representative of the intensity of light sampled by each sensor cell at the plurality of locations of the platform to corresponding polygon data.

32. The system of claim 31 wherein the mask pattern design database is comprised of polygon data representing an intended wafer image.

33. The system of claim 26 further including a database conversion processing unit to convert the polygon data of a first design database to the mask pattern design database comprised of intensity data wherein the intensity data for each spatial location corresponds to the polygon data for each associated spatial location.

34. The system of claim 26 wherein the processing unit generates the aerial image of the mask by interleaving the intensity data sampled by each sensor cell at the plurality of locations of the platform.

35. The system of claim 34 wherein the processing unit generates the aerial image of the mask using de-convolution.

36. The system of claim 34 wherein the processing unit compares the aerial image of the mask with an aerial image of the mask which is generated using the mask pattern design database.

37. The system of claim 34 wherein the processing unit compares the aerial image of the mask with a design-target of the wafer image of the mask.

49. The system of claim 34 wherein the second processing unit compares the aerial image of the mask with the design-target of the intended image of the mask.

38. A mask inspection system to detect defects in a mask used in the manufacture of integrated circuits, wherein the mask includes features having a line width, the system comprising:

an optical system to produce the image of the mask on a wafer plane;

a platform moveable between a plurality of locations in a first direction and a plurality of locations in a second direction;

an image sensor unit disposed on or in the moveable platform an located in the wafer plane, wherein the sensor array includes a plurality of sensor cell wherein each sensor cell includes an active area to sample light of a predetermined wavelength that is incident thereon, and wherein the sensor cells sample the intensity of light at a plurality of locations in the first and second directions;

a first processing unit, coupled to the image sensor unit, to generate image data which is representative of a portion of the aerial image of the mask wherein the portion of the aerial image includes a plurality of non-contiguous sub-images a wherein the processing unit generates each sub-image of the plurality of non-contiguous sub-images using the intensity of light sampled by a corresponding sensor cell when the platform is positioned at a plurality of locations relative to the aerial image, and wherein the non-contiguous sub-images include images of selected features of the mask;

a second processing unit, coupled to the first processing unit, to compare the image data generated by the first processing unit to data of a mask pattern design database, wherein the mask pattern design database includes data which is representative of the selected features on the mask.

39. The system of claim 38 wherein the mask pattern design database is a design-target of the wafer image of the mask.

40. The system of claim 38 wherein the mask pattern design database includes polygon data which is representative of the mask.

41. The system of claim 38 wherein the mask pattern design database includes intensity data which is representative of the mask.

42. The system of claim 38 further is including a film, disposed over the active areas of the plurality of sensor cells and comprised of a material that impedes passage of light of the predetermined wavelength, wherein the film includes a plurality of apertures which are arranged such that one aperture of the plurality of apertures overlies an associated active area of a corresponding sensor cell to expose a portion of the active area and wherein light of the predetermined wavelength is capable being sensed by the portion of the active area that is exposed by the associated aperture.

43. The system of claim 38 wherein the first and second processing units convert the data which is representative of the intensity of light sampled by each sensor cell at a plurality of locations in the first and second directions to corresponding polygon data.

44. The system of claim 43 wherein the mask pattern design database is comprised of polygon data representing an intended image.

45. The system of claim 38 further including a database conversion processing unit to convert the polygon data of a first design database to the mask pattern design database comprised of intensity data wherein the intensity data for each spatial location corresponds to the polygon data for each associated spatial location.

46. The system of claim 38 wherein the first processing unit generates the aerial image of the mask by interleaving the intensity data sampled by the sensor unit at a plurality of locations in the first and second directions of the platform.

47. The system of claim 46 wherein the first processing unit generates the aerial image of the mask using de-convolution.

48. The system of claim 46 wherein in the second processing unit compares the aerial image of the mask with an aerial image of the mask which is generated using the mask pattern design database.