Exposure apparatus and method which synchronously moves the mask and the substrate to measure displacement

• US 5,646,413 A
• Filed: 02/28/1996
• Issued: 07/08/1997
• Est. Priority Date: 02/26/1993
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Nishi, Kenji
• Primary Examiner(s): ALLEN, STEPHONE B
• Application Number:
  US08/608,086
• Time in Patent Office: 496 Days
• Field of Search: 250/201.2, 250/548, 355/53, 355/55, 355/43, 356/399-401
• US Class Current: 250/548
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position
• 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 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection

Abstract

There is disclosed an exposure method for transferring, using an optical system for illuminating a mask having patterns to be transferred on a substrate and a projection optical system for projecting images of the patterns to the substrate, the patterns to the substrate through the projection optical system by means of scanning the mask and the substrate synchronously relative to the projection optical system. The method comprises the steps of providing a plurality of measuring marks on the mask formed along a relative scanning direction, and providing a plurality of reference marks formed on the stage corresponding to the measuring marks, respectively, moving the mask and the substrate synchronously in the relative scanning direction to measure successively a displacement amount between the measuring marks on the mask and the reference marks, and obtaining a correspondence relation between a coordinate system on the mask and a coordinate system on the stage according to the displacement amount.

Claims

1. An exposure method for transferring, using an optical system for illuminating a mask having patterns to be transferred on a substrate and a projection optical system for projecting images of said patterns to said substrate, said patterns to said substrate through said projection optical system while scanning said mask and said substrate synchronously relative to said projection optical system, wherein said method comprises the steps of:

providing a plurality of measuring marks formed on said mask, and providing a plurality of reference marks formed on a stage for holding said substrate corresponding to said measuring marks;

measuring successively a displacement amount between said measuring marks on said mask and said reference marks while moving said mask and said reference marks synchronously; and

obtaining a correspondence relation between a coordinate system on said mask and a coordinate system on said stage according to said displacement amount.

2. An exposure method according to claim 1 further comprising the step of transferring said patterns to said substrate while scanning said mask and said substrate synchronously by using the corresponding relation between the coordinate system on said mask and the coordinate system on said stage.

3. An exposure method according to claim 1 further comprising the step of obtaining the corresponding relation between the coordinate system on said mask and the coordinate system on said stage by means of performing a least square approximation by using the displacement amount between said measuring marks and said reference marks.

4. An exposure method according to claim 1, wherein said mask is rectangular in shape and said measuring marks are provided at four corners of said mask.

5. An exposure method for transferring, using an exposure apparatus having an optical system for illuminating a mask having patterns to be transferred on a substrate, a mask stage for holding said mask, a substrate stage for holding said substrate, a projection optical system for projecting images of said patterns to said substrate, and an alignment system having its detection center at a position away from the optical axis of said projection optical system at a predetermined distance, said patterns to said substrate through said projection optical system while scanning said mask and said substrate synchronously relative to said projection optical system, wherein said method comprises the steps of:

providing a plurality of measuring marks formed on said mask;

providing first reference marks corresponding to a part of said measuring marks and second reference marks corresponding to said first reference marks, respectively, said first and said second reference marks being formed on said stage, said second reference marks being away from said first reference marks at a given distance that is recognized previously;

measuring successively a displacement amount between said measuring marks on said mask and said first reference marks while moving said mask with said second reference marks observed through said alignment system; and

obtaining a distance between a reference point within an exposing field of said projection optical system and said detection center according to said displacement amount between said measuring marks and said first reference marks, to a displacement amount of said second reference marks observed through said alignment system, and to said given distance previously recognized.

6. An exposure method for transferring, using an exposure apparatus having an optical system for illuminating a mask having patterns to be transferred on a substrate, a mask stage for holding said mask, a substrate stage for holding said substrate, a projection optical system for projecting images of said patterns to said substrate, and an alignment system having its detection center at a position away from the optical axis of said projection optical system at a predetermined distance, said patterns to said substrate through said projection optical system while scanning said mask and said substrate synchronously relative to said projection optical system, wherein said method comprises the steps of:

providing a plurality of measuring marks formed on said mask;

providing first reference marks corresponding to each of said measuring marks and second reference marks corresponding to said first reference marks, respectively, said first and said second reference marks being formed on said stage, said second reference marks being away from said first reference marks at a given distance that is recognized previously;

measuring successively a displacement amount between said measuring marks on said mask and said first reference marks while moving said mask and said first reference marks synchronously;

measuring successively a displacement amount of said second reference marks while moving said mask and said second reference marks relatively; and

obtaining a distance between a reference point within an exposing field of said projection optical system and said detection center according to said displacement amount between said measuring marks and said first reference marks, to a displacement amount of said second reference marks observed through said alignment system, and to said given distance previously recognized.

7. An exposure method according to claim 6 further comprising the steps of transferring said patterns to said substrate while scanning said mask and said substrate synchronously by using said obtained distance between the reference point within the exposing field of said optical projection system and said detection center.

8. An exposure method according to claim 6 further comprising the step of obtaining a distance between the reference point within the exposing field of said projection optical system and said detection center according to an offset component obtained by means of performing a least square approximation using the displacement amount between said measuring marks and said first reference marks, to the displacement amount of said second reference marks, and to said given distance previously recognized.

9. An exposure method for transferring, by means of illuminating an illumination area of a predetermined shape using an illumination light to scan a mask and a substrate synchronously relative to said illumination area of the predetermined shape, patterns on said mask within said illumination area of the predetermined shape through a projection optical system to said substrate on a stage, wherein said method comprises,

with a plurality of measuring marks formed on said mask and reference marks formed on said stage corresponding to said measuring marks,

a first step for measuring a displacement amount between a part of said measuring marks and said reference marks corresponding to the part of said measuring marks;

a second step for measuring successively a displacement amount between said measuring marks on said mask and said reference marks corresponding to said measuring marks while moving said mask and said reference marks synchronously; and

a third step for selecting one of said first and said second steps to obtain a corresponding relation between a coordinate system on said mask and a coordinate system on said stage according to the displacement amount between said measuring marks and said reference marks, respectively, obtained at the selected step.

10. An exposure method for transferring, using an exposure apparatus having an optical system for illuminating an illumination area of a predetermined shape using an illumination light, a mask stage for holding a mask provided with patterns to be reproduced, a substrate stage for holding a substrate, a projection optical system for projecting images of the patterns on said mask to said substrate, an alignment system having its detection center at a position away from the optical axis of said projection optical system at a predetermined position, the patterns on said mask in said illumination area of the predetermined shape through said projection optical system to said substrate while scanning said mask and said substrate synchronously relative to said illumination area of the predetermined shape, wherein said method comprises,

with a plurality of measuring marks formed on said mask and a plurality of first reference marks corresponding to said measuring marks and second reference marks corresponding to said first reference marks, said first and said second reference marks being formed on said stage, said second reference marks being away from said first reference mark at a given distance that is recognized previously,

a first step for measuring a displacement amount between a part of said measuring marks on said mask and said first reference marks corresponding to the part of said measuring marks, respectively, and measuring a displacement amount between said second reference marks corresponding to the part of said first reference marks;

a second step for measuring successively a displacement amount between said measuring marks and said first reference marks corresponding to said measuring marks, respectively, and a displacement amount of said second reference marks while moving said mask and said first reference marks synchronously;

a third step for selecting one of said first and said second step; and

a fourth step for obtaining a corresponding relation between a coordinate system on said mask stage and a coordinate system on said substrate stage and a distance between a reference point within an exposing field of said projection optical system and said detection center according to information obtained during the step selected at said third step and said given distance previously recognized.

11. An exposure method for transferring, using an exposure apparatus having an optical system for illuminating an illumination area of a predetermined shape using an illumination light, a mask stage for holding a mask provided with patterns to be transferred, a substrate stage for holding a substrate, a projection optical system for projecting images of the patterns on said mask to said substrate, an alignment system having its detection center at a position away from the optical axis of said projection optical system at a predetermined position, the patterns on said mask in said illumination area of the predetermined shape through said projection optical system to said substrate while scanning said mask and said substrate synchronously relative to said illumination area of the predetermined shape, wherein the method comprises,

with a plurality of measuring marks formed on said mask and a plurality of first reference marks corresponding to said measuring marks and second reference marks corresponding to said first reference marks, said first and said second reference marks being formed on said stage, said second reference marks being away from said first reference marks at a given distance that is recognized previously, for every replacement of predetermined number of substrates,

a step for measuring a displacement amount between a part of said measuring marks on said mask and said first reference marks corresponding to the part of said measuring marks, respectively, and measuring a displacement amount between said second reference marks corresponding to the part of said first reference marks;

and

a step for obtaining a corresponding relation between a coordinate system on said mask and a coordinate system on said stage and a distance between a reference point within an exposing field of said projection optical system and said detection center according to a displacement amount between one measuring mark and one first reference mark, to a displacement amount of said second reference marks, and to said given distance recognized previously.

12. An exposure method for transferring, by an illumination system illuminating an illumination area of a predetermined shape using an illumination light and scanning a mask and a substrate synchronously relative to said illumination area of the predetermined shape, patterns on said mask in said illumination area of the predetermined shape to said substrate on a stage through a projection optical system, wherein said method comprises,

with a plurality of measuring marks formed on said mask and a plurality of reference marks formed on said stage corresponding to a part of said measuring marks,

the steps of:

measuring successively a displacement amount between said measuring marks on said mask and said reference marks while moving said mask; and

obtaining a corresponding relation between a coordinate system on said mask and a coordinate system on said stage.

13. An exposure method for transferring, using an exposure apparatus having an optical system for illuminating an illumination area of a predetermined shape using an illumination light, a mask stage for holding a mask provided with patterns to be transferred, a substrate stage for holding a substrate, a projection optical system for projecting images of the patterns on said mask to said substrate, an alignment system having its detection center at a position away from the optical axis of said projection optical system at a predetermined position, the patterns on said mask in said illumination area of the predetermined shape through said projection optical system to said substrate while scanning said mask and said substrate synchronously relative to said illumination area of the predetermined shape, wherein said method comprises the steps of:

forming on said substrate stage a reference mark detectable by said alignment system to measure a displacement amount of said reference marks by said alignment system;

entering a mark error of said mask; and

obtaining a corresponding relation between a coordinate system on said mask stage and a coordinate system on said substrate stage, and a distance between a reference point within an exposing field of said projection optical system and said detection center.

14. An exposure apparatus comprising a mask stage for holding a mask provided with patterns to be transferred, a substrate stage for holding a substrate;

an optical system for illuminating said mask using an illumination light;

a projection optical system for projecting images of the patterns on said mask to said substrate; and

a first mark detecting system for detecting a mask mark formed at a predetermined position on said mask within an exposing field of said projection optical system, said apparatus being for transferring the patterns on said mask to said substrate through said projection optical system while scanning said mask and said substrate synchronously relative to said projection optical system, wherein said apparatus comprises;

a reference plate provided on said substrate stage, said reference plate comprising a plurality of first reference marks detectable by said first mark detecting system through said projection optical system;

a plurality of measuring marks provided on said mask, each of said measuring marks being correspondent with a reference mark;

a driving control system for moving said mask stage and said substrate stage synchronously so that said first mark detecting system observes a part of said first reference marks and a part of said measuring marks to measure successively a displacement amount between said measuring marks on said mask and said reference marks; and

a calculator for calculating a corresponding relation between a coordinate system on said mask stage and a coordinate system on said substrate stage.

15. An apparatus according to claim 14, wherein said mask is rectangular in shape and said measuring marks are provided at four corners of said mask.

16. An exposure apparatus comprising a mask stage for holding a mask provided with patterns to be transferred;

a substrate stage for holding a substrate;

an optical system for illuminating said mask using an illumination light;

a projection optical system for projecting images of the patterns on said mask to said substrate;

a first mark detecting system for detecting a mask mark formed at a predetermined position on said mask within an exposing field of said projection optical system; and

a second mark detecting system having its detection center at a position away from the optical axis of said projection optical system at a predetermined position, said apparatus being for transferring the patterns on said mask to said substrate through said projection optical system while scanning said mask and said substrate synchronously relative to said projection optical system, wherein said apparatus further comprises;

a reference plate provided on said substrate stage, said reference plate comprising a plurality of first reference marks detectable by said first mark detecting system through said projection system and second reference marks provided away from said first reference marks at a given distance that is recognized previously;

a plurality of measuring marks provided on said mask, each of said measuring marks being correspondent with a first reference mark;

a driving control system for moving said mask stage and said substrate stage so that said first mark detecting system observes a part of said measuring marks and a part of said first reference marks in a state that said second mark detecting system observes one of said second reference marks and so that a displacement amount between said measuring marks on said mask and said first reference marks and a displacement amount of said second reference marks are measured successively; and

a calculator for calculating a corresponding relation between a coordinate system on said mask stage and a coordinate system on said substrate stage and a distance between a reference point within an exposing field of said projection optical system and said detection center according to said displacement amounts measured.

17. An exposure method for transferring a pattern formed on a mask onto a substrate, comprising the steps of:

scanning said mask and said substrate synchronously relative to a projection optical system for projecting an image of said pattern to said substrate, a plurality of measuring marks provided along a relative scanning direction being formed on said mask, and a plurality of reference marks being formed at a location optically substantially conjugated with said mask;

measuring a displacement amount between said measuring marks and said reference marks; and

obtaining a correspondence relation between a coordinate system on a mask stage for holding said mask and a coordinate system on a substrate stage for holding said substrate based on said displacement amount.

18. An exposure method according to claim 17, wherein said measuring step includes:

moving said mask and said reference marks by predetermined distances respectively in said scanning direction to successively measure a displacement amount between said measuring marks and said reference marks.

19. An exposure method according to claim 17, wherein said measuring step includes:

moving at least one of said mask and said reference marks in said scanning direction to successively measure a displacement amount between said measuring marks and said reference marks.

20. An exposure method according to claim 17, wherein said reference marks are provided on said substrate stage for holding said substrate.

21. An exposure method for transferring a pattern formed on a mask onto a substrate, a plurality of measuring marks being formed on said mask, and a plurality of reference marks being formed at a location optically substantially conjugated with said mask, said method comprising the steps of:

moving at least one of said mask and said reference marks to successively measure a displacement amount between said measuring marks and said reference marks;

obtaining an imaginary coordinate system on said mask based on said displacement amount; and

obtaining a writing error of said measuring marks based on said imaginary coordinate system.

22. An exposure method according to claim 21, wherein said step of obtaining an imaginary coordinate system includes:

performing a statistical calculation by using a coordinate system on said mask and said displacement amount to obtain an imaginary coordinate system.

23. An exposure method according to claim 22, wherein said statistical calculation is a least square approximation.

24. An exposure method according to claim 21, wherein said step of obtaining a writing error includes:

obtaining a writing error by using a coordinate system on said mask, said displacement amount and said imaginary coordinate system.

25. An exposure method according to claim 21, wherein said step of obtaining a writing error includes:

obtaining a writing error by subtracting said imaginary coordinate system from a coordinate system on said mask and said displacement amount.

26. An exposure method according to claim 21, further comprising the step of:

correcting said writing error to obtain a correspondence relation between a coordinate system on said mask and a coordinate system on a substrate stage for holding said substrate.

27. An exposure method according to claim 21, further comprising the step of:

scanning said mask and said substrate synchronously relative to an illumination area of a predetermined shape for illuminating said mask to transfer said pattern onto said substrate.

28. An exposure method according to claim 21, wherein said reference marks are provided on a substrate stage for holding said substrate.

29. An exposure method for transferring a pattern formed on a mask onto a substrate through a projection optical system, a plurality of measuring marks being formed on said mask, and first and second reference marks being formed at a location optically substantially conjugated with said mask, said method comprising the steps of:

measuring a first displacement amount between said measuring marks and said first reference mark;

measuring a second displacement amount of said second reference mark; and

obtaining a distance between a detection point of an alignment system for detecting an alignment mark on said substrate and a reference point within an exposing field of said projection optical system based on said first and second displacement amounts.

30. An exposure method according to claim 29, further comprising the step of:

obtaining a correspondence relation between a coordinate system on said mask and a coordinate system on a substrate stage for holding said substrate based on said first displacement amount.

31. An exposure method according to claim 30, further comprising the step of:

scanning said mask and said substrate synchronously relative to a projection optical system based on said distance and said correspondence relation to transfer said pattern onto said substrate.

32. An exposure method according to claim 29, wherein said reference marks are provided on a substrate stage for holding said substrate.

33. An exposure method for transferring a pattern formed on a mask onto a substrate, comprising the steps of:

scanning said mask and said substrate synchronously relative to an illumination light for illuminating said mask;

measuring a displacement amount between measuring marks provided on said mask and reference marks provided at a location optically substantially conjugated with said mask; and

transferring said pattern formed on said mask onto said substrate based on said displacement amount where said reference marks are provided on a substrate stage for holding said substrate.

34. An exposure method for transferring a pattern formed on a mask onto a substrate, comprising the steps of:

scanning said mask and said substrate synchronously relative to a projection optical system for projecting an image of said pattern to said substrate;

obtaining a mark error of said mask;

correcting at least one of a corresponding relation between a coordinate system on the mask side and a coordinate system on the substrate side, and a distance between a reference point within an exposing field of said projection optical system and a detection center of an alignment system which detects a mark on said substrate.