Exposure method and apparatus

• US 6,163,366 A
• Filed: 11/12/1997
• Issued: 12/19/2000
• Est. Priority Date: 09/13/1995
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Okamoto, Hiroki, Kawakubo, Masaharu, Mizutani, Shinji
• Primary Examiner(s): Rutledge, D.
• Application Number:
  US08/968,422
• Time in Patent Office: 1,133 Days
• Field of Search: 355/43-45, 355/53, 355/67, 355/68, 355/77, 356/124, 356/400, 356/401, 250/548, 250/557
• US Class Current: 355/53
• CPC Class Codes: G03F 7/70458 Mix-and-match, i.e. multiple exposures of the same area using a similar type of exposure apparatus, e.g. multiple exposures using a UV apparatus
• CPC Class Codes: G03F 7/70883 of optical system
• CPC Class Codes: G03F 9/7003 Alignment type or strategy, e.g. leveling, global alignment

Abstract

In the exposure method and apparatus, the distortion data of the projection lens in each exposure unit itself has already been known for each exposure unit. Accordingly, when the exposure unit which formed the alignment target layer has already been known, the known data of this exposure unit is used to correct at least one of the projection magnification and shot rotation determined according to multipoint EGA operation, and the exposure apparatus is adjusted by the amount of this correction. When the exposure unit forming the alignment target layer is unknown, the alignment mark exposure unit is specified from the state of distribution of non-linear error computed from the alignment mark measured values within a shot. Under thus determined correct projection magnification and shot rotation, a shot area is accurately overlaid with and exposed to a reticle pattern.

Claims

1. An exposure method in which a plurality of reticle patterns are sequentially overlaid with and projected onto a plurality of shot areas formed on a substrate to be processed, said method comprising the steps of:

measuring positions of a plurality of alignment marks formed within said shot areas;

computing, from thus measured positions of alignment marks and designed position of the alignment marks, an error therebetween;

comparing known distortion data of a plurality of projection lenses and said error with each other so as to specify the projection lens used for forming the alignment marks;

using the distortion data of thus specified projection lens and said error so as to correct a projection image of a reticle pattern; and

performing exposure with thus corrected projection image.

2. An exposure method according to claim 1, wherein at least one of magnification of the projection image of the reticle pattern and rotation of the projection image of the reticle pattern is adjusted so as to correct said projection image.

3. An exposure method according to claim 1, further comprising a step of extracting, from said error, a non-linear component thereof, wherein thus extracted non-linear component of the error and the known distortion data of the plurality of projection lenses are compared with each other so as to specify the projection lens used for forming the alignment marks.

4. A method according to claim 1, wherein a micro-device is fabricated by exposing the reticle pattern onto the substrate.

5. An exposure method in which a reticle pattern is projected to a substrate to be processed, said method comprising the steps of:

measuring positions of a plurality of alignment marks formed within said substrate;

computing, from thus measured positions of the alignment marks and designed positions of the alignment marks, an error therebetween; and

determining, from a predetermined distortion data of a projection lens used for forming said alignment marks and said error, an amount of positional deviation of a projection image of a reticle pattern.

6. A method according to claim 5, wherein a micro-device is fabricated by exposing the reticle pattern onto the substrate.

7. An exposed method in which a predetermined mark is exposed to a substrate by way of a projection optical system, said method comprising the steps of:

detecting information regarding a position of alignment marks formed on said substrate;

extracting a non-linear component from the detected information; and

determining image characteristics of said projection optical system used for forming said alignment mark based on said extracted non-linear component.

8. An exposure method according to claim 7, wherein said image characteristics includes a distortion characteristic.

9. A method according to claim 7, wherein a micro-device is fabricated by exposing the reticle pattern onto the substrate.

10. A method of detecting a mark in which a mark formed on a substrate by way of a projection optical system is detected, said method comprising the steps of:

detecting information regarding a position of said mark; and

correcting said information regarding a position of said mark based on characteristics information regarding an image of said projection optical system which formed said mark.

11. A method according to claim 10, wherein a plurality of shots are formed on said substrate and a plurality of alignment marks of each of said shots are detected.

12. A method according to claim 11, wherein at least one of magnification, rotation and distortion of each of said shots is detected by the detected alignment mark of each of said shots.

13. A method according to claim 10, wherein a micro-device is fabricated by exposing a predetermined pattern onto the substrate which is positioned based on said information detected and corrected.

14. An exposure method in which a plurality of reticle patterns are sequentially overlaid with and projected onto a plurality of shot areas formed on a substrate to be processed, the method comprising the steps of:

obtaining information regarding positions of a plurality of marks formed in said plurality of shot areas;

obtaining distortion information regarding distortions in previous shot areas based on said position information; and

adjusting a pattern image of said reticle based on said position and distortion information.

15. An exposure method according to claim 14, wherein said distortion information includes information regarding distortion of a projection optical system used in formation of plurality of shot areas.

16. An exposure method according to claim 14, wherein the adjusting step includes adjustment of a magnification of said pattern image.

17. An exposure method according to claim 16, wherein the adjusting step includes adjusting in relative rotation between pattern image and said plurality of shot areas.

18. An exposure method according to claim 15, wherein said information regarding the distortions is selected from pre-stored distortion data of a plurality of projection optical systems.

19. An exposure method according to claim 14, wherein said plurality of alignment marks are used for adjusting relative positional relationships between said pattern image of said reticle and said plurality of shot areas.

20. An exposure method according to claim 17, wherein said plurality of alignment marks are used for adjusting relative positional relationships between said pattern image of said reticle and said plurality of shot areas.

21. A method according to claim 14, wherein a micro-device is fabricated by exposing the reticle pattern onto the substrate.

22. An exposure method in which a plurality of reticle patterns are sequentially overlaid with and projected onto a plurality of shot areas formed on a substrate to be processed, the method comprising the steps of:

measuring positions of a plurality of alignment marks formed with said plurality of shot areas;

computing, from the measured positions and from designed positions of said plurality of alignment marks, an error therebetween;

comparing known distortion data of a plurality of projection lenses and said error with each other so as to specify one of said plurality of projection lens to be used for forming the plurality of alignment marks;

using the distortion data of the specified projection lens and said error so as to correct a projection image of a reticle pattern; and

performing exposure with the corrected projection image.

23. An exposure method according to claim 22, wherein at least one of magnification of the projection image of the reticle pattern and rotation of the projection image of the reticle pattern is adjusted so as to correct the projection image.

24. An exposure method according to claim 22, further comprising a step of extracting, from said error, a non-linear component thereof,

wherein the extracted non-linear component of said error and the known distortion data of said plurality of projection lenses are compared with each other so as to specify the one of said plurality of projection lenses used for forming said plurality of alignment marks.

25. A method according to claim 22, wherein a micro-device is fabricated by exposing the reticle pattern onto the substrate.

27. An exposure method according to claim 22, wherein, at the correcting step, an amount of correction for the projection image formed by said second exposure apparatus at which overlay accuracy between the respective projection images formed by said first and second exposure apparatuses is optimized is determined from the stored distortion data and, based on amounts of positional deviation in the projection images in said first and second exposure apparatuses at the determined amount of the projection image of said first reticle pattern, the projection image formed by said second exposure apparatus is corrected.

26. An exposure method in which a plurality of reticle patterns are sequentially overlaid with and projected, by a plurality of exposure apparatuses, onto a plurality of shot areas formed on a substrate to be processed, the method comprising the steps of:

determining distortion data of projection images respectively formed by said plurality of exposure apparatuses;

storing the determined distortion data;

determining an amount of positional deviation of the projection image of the first reticle pattern formed by the first exposure apparatus at a fixed measurement point on said substrate before exposure of a second layer on said substrate is performed by the second exposure apparatus;

correcting, based on the stored distortion data and the amount of positional deviation, the projection image formed by said second exposure apparatus; and

performing exposure by said second exposure apparatus with the corrected projection image and, at the correcting step, an amount of correction for the projection image formed by said second exposure apparatus at which overlay accuracy between the respective projection images formed by said first and second exposure apparatuses is optimized is determined from the stored distortion data and, based on amounts of positional deviation in the projection images in said first and second exposure apparatuses at the determined amount of the projection image of said first reticle pattern, the projection image formed by said second exposure apparatus is corrected.

28. A method according to claim 26, wherein a micro-device is fabricated by exposing the reticle pattern onto the substrate.

29. An exposure method for exposing a predetermined pattern onto a substrate by way of a projection system, said method comprising the steps of:

measuring a mark formed on the substrate;

obtaining first information regarding a position of the mark based on the measuring result;

obtaining second information which includes known characteristics regarding a projection image projected onto the substrate when the mark is formed, the second information being obtained based on said first information; and

controlling projection of the predetermined pattern onto the substrate based on the first and second information.

30. An exposure method according to claim 29, wherein said first information includes deviation information between measured position of the mark and designed position of the mark.

31. An exposure method according to claim 30, wherein said second information obtaining step includes:

accessing a memory which has a plurality of said second specific information respectively corresponding to a plurality of projection systems;

comparing said second information of a plurality of the projection system and said first information with each other so as to specify the projection system using for forming the mark; and

specifying said second information corresponding to said specified projection system.

32. An exposure method according to claim 30, wherein said controlling step includes:

determining a position deviation of a projection image of said predetermined pattern based on said deviation information and said second information; and

controlling a projection position on the substrate of said predetermined pattern based on said positional deviation determined by the determining step.

33. An exposure method according to claim 29, wherein said second information includes a distortion information of a projection system which projected the mark onto the substrate.

34. An exposure method according to claim 29, wherein said controlling step includes adjusting a projection image of said predetermined pattern.

35. An exposure method according to claim 34, wherein said adjusting step includes controlling magnification of the projection system.

36. An exposure method according to claim 29, wherein said controlling step includes controlling a projection position of said predetermined pattern on the substrate.

37. An exposure method according to claim 29, wherein said second information includes a distortion information of a projection system that projected the mark onto the substrate, and controlling step includes correcting said first information based on said second information.

38. An exposure method according to claim 29, wherein said mark is exposed onto the substrate by a first exposure apparatus, and said predetermined pattern is exposed onto the substrate by a second exposure apparatus different from the first exposure apparatus.

39. An exposure method according to claim 38, wherein said second information includes known first characteristics information that a projection image projected by said first exposure apparatus has, and further comprising:

obtaining known second characteristics information that a projection image projected by said second exposure apparatus has.

40. An exposure method according to claim 39, wherein said controlling step includes:

adjusting a projection image that is projected by said second exposure apparatus based on said first information, said first characteristics information and said second characteristics information.

41. An exposure method according to claim 40, wherein said adjusting step includes controlling magnification of the projection image.

42. An exposure method according to claim 29, further comprising the steps of:

measuring said second information; and

storing said second information measured by the measuring step.

43. A method for fabricating a micro-device by exposing the predetermined pattern onto the substrate using the exposure method according to claim 29.

44. A projection exposure apparatus which exposes a predetermined pattern on to a substrate by way of a projection system, said apparatus comprising:

a first obtaining unit, having a observing system that observes said substrate, which measures a mark formed on the substrate by the observing unit and obtains first information regarding to position of the mark;

a second obtaining unit, which is electrically connected to a memory, and which obtains second information that corresponds to known characteristics with respect to a projection image projected onto the substrate when the mark is formed, the second information being obtained based on said first information; and

a controller, which is electrically connected to said first and second obtaining unit, and which controls projection of the predetermined pattern onto the substrate based on the first and second information.

45. An apparatus according to claim 44, wherein said mark is exposed onto the substrate by a predetermined exposure apparatus different from said projection exposure apparatus.

46. An apparatus according to claim 45, wherein said second information includes known first characteristics information that a projection image projected by said predetermined exposure apparatus has, and further comprising:

a third obtaining unit, which is electrically connected to said memory, and which obtains known second characteristics information that a projection image projected by said projection exposure apparatus has, and wherein said controller adjusts a projection image that is projected by said projection exposure apparatus based on said first information, said first characteristics, said first characteristics information and said second characteristics information.

47. An apparatus according to claim 46, wherein said controller controls magnification of the projection image.

48. An apparatus according to claim 44, wherein said memory includes a data-base device that is electrically connected to said projection exposure apparatus.

49. An apparatus according to claim 44, wherein said memory is arranged in said projection exposure apparatus.

50. An apparatus according to claim 44, wherein said memory has a plurality of specific information respectively corresponding to a plurality of exposure apparatuses, said second obtaining unit further comprising:

a comparator, which is electrically connected to said first obtaining unit and said memory, and which compares a plurality of said second information and said first information with each other so as to specify one second information.

51. An apparatus according to claim 50, wherein said first information includes deviation information between measured position of the mark and designed position of the mark.

52. An apparatus according to claim 44, wherein said second information includes a distortion information of a projection system which projected the mark onto the substrate.

53. An apparatus according to claim 44, wherein said controller controls magnification of the projection image of the predetermined pattern.

54. An apparatus according to claim 44, wherein said controller controls projection position of said predetermined pattern on the substrate.

55. A micro-device manufactured by exposing the predetermined pattern onto the substrate via the projection exposure apparatus of claim 44.