Projection exposure apparatus and method

• US 6,400,441 B1
• Filed: 09/20/2000
• Issued: 06/04/2002
• Est. Priority Date: 11/28/1996
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Nishi, Kenji, Ota, Kazuya
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): NGUYEN, HUNG
• Application Number:
  US09/666,407
• Time in Patent Office: 622 Days
• Field of Search: 355/53, 355/55, 355/72-77, 355/67, 356/399-401, 250/548
• US Class Current: 355/53
• CPC Class Codes: G03F 7/70216 Mask projection systems
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70425 Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
• CPC Class Codes: G03F 7/70716 Stages
• CPC Class Codes: G03F 7/70733 Handling masks and workpieces, e.g. exchange of workpiece or mask, transport of workpiece or mask
• CPC Class Codes: G03F 9/70 for microlithography measuring printed patterns for monitoring overlay G03F7/70633 or focus G03F7/70641; projection system adjustment G03F7/70258; position control G03F7/70775
• CPC Class Codes: G03F 9/7003 Alignment type or strategy, e.g. leveling, global alignment
• CPC Class Codes: G03F 9/7015 Reference, i.e. alignment of original or workpiece with respect to a reference not on the original or workpiece
• CPC Class Codes: G03F 9/7026 Focusing
• CPC Class Codes: G03F 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection

Abstract

Two stages (WS1), (WS2) holding wafers can independently move between a positional information measuring section (PIS) under an alignment system (24a) and an exposing section (EPS) under a projection optical system (PL). The wafer exchange and alignment are performed on the stage (WS1), during which wafer (W2) is exposed on the stage (WS2). A position of each shot area of wafer (WS1) is obtained as a relative position with respect to a reference mark formed on the stage (WS1) in the section (PIS). Relative positional information can be used for the alignment with respect to an exposure pattern when the wafer (WS1) is moved to the section (EPS) to be exposed. Therefore, it is not necessary that a stage position is observed continuously in moving the stage. Exposure operations are performed in parallel by the two wafer stages (WS1) and (WS2) so as to improve the throughput.

Claims

1. A projection exposure method for exposing sensitive substrates by projecting a pattern formed on a mask through a projection optical system onto the sensitive substrates, comprising:

preparing a first substrate stage and a second substrate stage, each of which is movable independently on a two-dimensional plane while holding a sensitive substrate; and

performing, by using the first substrate stage, at least one of an exchange operation for the sensitive substrate and a detecting operation for a mark on the first stage or on the sensitive substrate held on the first stage, while executing a scanning exposure operation for the sensitive substrate held on the second substrate stage, wherein each of shot areas on the sensitive substrate held on the second substrate stage is exposed by moving the second substrate stage while projecting the pattern on the mask onto the sensitive substrate held on the second substrate stage, and wherein the two substrate stages are controlled such that the two substrate stages do not physically interfere with each other.

2. The projection exposure method according to claim 1, wherein the operations of the two substrate stages are switched between one another when the operations of the two substrate stages are completed.

3. The projection exposure method according to claim 2, wherein moving regions of the two substrate stages are switched between one another when the operations of the two substrate stages are completed.

4. The projection exposure method according to claim 1, wherein the second substrate stage is prevented from vibration when the first substrate stage is moved.

5. The projection exposure method according to claim 1, wherein a moving region of the first substrate stage which executes the at least one of the exchange operation and the detection operation overlaps a moving region of the second substrate stage which executes the scanning exposure operation.

6. A method for making a device, the method comprising performing a lithography process utilizing the method defined in claim 1.

7. The projection exposure method according to claim 1, wherein predetermined information is stored to prevent the two substrate stages from physically interfering with each other.

8. The projection exposure method according to claim 1, wherein the first substrate stage is moved to sequentially detect a plurality of marks on the substrate held on the first substrate stage in the detecting operation.

12. A method for making a device, the method comprising performing a lithography process utilizing the method defined in claim 2.

9. A projection exposure method for exposing sensitive substrates by projecting an image of a pattern formed on a mask via a projection optical system onto the sensitive substrates, comprising:

preparing a first substrate stage and a second substrate stage, each of which moves independently on a two-dimensional plane while holding a sensitive substrate; and

successively exposing, by projection, a plurality of portions on the sensitive substrate held on the first substrate stage with the image of the pattern formed on the mask, and successively detecting a plurality of marks on the sensitive substrate held on the second substrate stage concurrently therewith, wherein an order of the detection of the marks on the sensitive substrate held on the second substrate stage is determined so that the two substrate stages do not physically interfere with each other.

10. The projection exposure method according to claim 9, wherein each of the portions on the sensitive substrate held on the first substrate stage is exposed with a scanning exposure operation.

11. The projection exposure method according to claim 9, wherein the first substrate stage is prevented from vibration when the second substrate stage is moved.

13. A projection exposure method for exposing sensitive substrates by projecting a pattern formed on a mask through a projection optical system onto the sensitive substrates, comprising:

preparing a first substrate stage and a second substrate stage, each of which is movable independently on a two-dimensional plane while holding a sensitive substrate; and

performing, by using the first substrate stage, at least one of an exchange operation for the sensitive substrate and a detecting operation for a mark on the first substrate stage or on the sensitive substrate held on the first substrate stage, while executing an exposure operation for the sensitive substrate held on the second substrate stage, wherein a moving region of the first substrate stage which executes the at least one of the exchange operation and the detecting operation overlaps a moving region of the second substrate stage which executes the exposure operation and wherein the two substrate stages are controlled such that the two substrate stages do not physically interfere with each other.

14. The projection exposure method according to claim 13, wherein the second substrate stage is prevented from vibration when the first substrate stage is moved.

15. The projection exposure method according to claim 13, wherein predetermined information is stored to prevent the two substrate stages from physically interfering with each other.

16. The projection exposure method according to claim 13, wherein the first substrate stage is moved to sequentially detect a plurality of marks on the substrate held on the first substrate stage in the detecting operation.

17. The projection exposure method according to claim 13, wherein the operations of the two substrate stages are switched between one another when the operations of the two substrate stages are completed.

18. The projection exposure method according to claim 17, wherein moving regions of the two substrate stages are switched between one another when the operations of the two substrate stages are completed.

19. A method for making a device, the method comprising performing a lithography process utilizing the method defined in claim 13.

20. A projection exposure apparatus for sequentially exposing sensitive substrates by projecting a pattern formed on a mask illuminated with an exposure beam, the apparatus comprising:

a projection system, disposed in a path of the exposure beam, which projects the pattern onto a sensitive substrate;

a stage system, disposed on an image plane side of the projection system, which has a first substrate stage and a second substrate stage, each of which is movable independently in a plane while holding a sensitive substrate; and

a control system, functionally associated with the stage system, which controls the stage system to perform, by controlling the first substrate stage, at least one of an exchange operation for the sensitive substrate and a detecting operation for a mark on the first substrate stage or on the sensitive substrate held on the first substrate stage, while executing a scanning exposure operation for the sensitive substrate held on the second substrate stage, wherein each of shot areas on the sensitive substrate held on the second substrate stage is exposed while moving the second substrate stage, and wherein the control system controls the two substrate stages such that the two substrate stages do not physically interfere with each other.

21. The projection exposure apparatus according to claim 20, further comprising:

a detecting system, functionally connected with the control system, which detects the mark on the first substrate stage or on the sensitive substrate held on the first substrate stage, wherein the detecting system sequentially detects a plurality of marks on the sensitive substrate held on the first substrate stage.

22. The projection exposure apparatus according to claim 21, wherein the control system performs statistical calculation based on information detected by the detecting system to obtain positional information of shot areas on the sensitive substrate held on the first substrate stage.

23. The projection exposure apparatus according to claim 21, wherein the detecting system includes a first detector to detect the marks on the sensitive substrate held on the first substrate stage and a second detector to detect a plurality of marks on the sensitive substrate held on the second substrate stage.

24. The projection exposure apparatus according to claim 20, further comprising:

an interferometer system, functionally associated with the stage system and the control system, which has a plurality of measurement axes and measures positions of the two substrate stages; and

a linear motor system, magnetically connected to the two substrate stages, which moves the two substrate stages based on the positions measured by the interferometer system.

25. The projection exposure apparatus according to claim 20, further comprising:

an exchange system, functionally associated with the stage system and the control system, which includes a first exchanger which performs substrate transfer between itself and the first substrate stage and a second exchanger which performs substrate transfer between itself and the second substrate stage.

26. The projection exposure apparatus according to claim 20, wherein the control system stores information to prevent the two substrate stages from interfering with each other.

27. The projection exposure apparatus according to claim 20, wherein a moving region of the first substrate stage which executes the at least one of the exchange operation and the detecting operation overlaps a moving region of the second substrate stage which executes the scanning exposure operation.

28. The projection exposure apparatus according to claim 20, wherein the second substrate stage is prevented from vibration when the first substrate stage is moved.

29. A projection exposure apparatus for sequentially exposing sensitive substrates by projecting a pattern formed on a mask illuminated with an exposure beam, the apparatus comprising:

a projection system, disposed in a path of the exposure beam, which projects the pattern onto a sensitive substrate;

a stage system, disposed on an image plane side of the projection system, which has a first substrate stage and a second substrate stage, each of which is movable independently in a plane while holding a sensitive substrate; and

a control system, functionally associated with the stage system, which controls the stage system to perform, by controlling the first substrate stage, at least one of an exchange operation for the sensitive substrate and a detecting operation for a mark on the first substrate stage or on the sensitive substrate held on the first substrate stage, while executing an exposure operation for the sensitive substrate held on the second substrate stage, wherein a moving region of the first substrate stage during the at least one of the exchange operation and the detecting operation overlaps a moving region of the second substrate stage of the two substrate stages during the exposure operation, and wherein the control system controls the two substrate stages such that the two substrate stages do not physically interfere with each other.

30. The projection exposure apparatus according to claim 29, further comprising:

a detecting system, functionally connected with the control system, which detects the mark on the first substrate stage or on the sensitive substrate held on the first substrate stage, wherein the detecting system sequentially detects a plurality of marks on the sensitive substrate held on the first substrate stage.

31. The projection exposure apparatus according to claim 30, wherein the control system performs statistical calculation based on information detected by the detecting system to obtain positional information of shot areas on the sensitive substrate held on the first substrate stage.

32. The projection exposure apparatus according to claim 30, wherein the detecting system includes a first detector to detect the marks on the sensitive substrate held on the first substrate stage and a second detector to detect a plurality of marks on the sensitive substrate held on the second substrate stage.

33. The projection exposure apparatus according to claim 29, further comprising:

an interferometer system, functionally associated with the stage system and the control system, which has a plurality of measurement axes and measures positions of the two substrate stages; and

a linear motor system, magnetically connected to the two substrate stages, which moves the two substrate stages based on the positions measured by the interferometer system.

34. The projection exposure apparatus according to claim 29, further comprising:

an exchange system, functionally connected with the control system, which includes a first exchanger which performs substrate transfer between itself and the first substrate stage and a second exchanger which performs substrate transfer between itself and the second substrate stage.

35. The projection exposure apparatus according to claim 29, wherein the control system stores information to prevent the two substrate stages from interfering with each other.

36. The projection exposure apparatus according to claim 29, wherein the second substrate stage is prevented from vibration when the first substrate stage is moved.