Exposure apparatus and exposure method capable of controlling illumination distribution

• US 20030025890A1
• Filed: 02/23/2001
• Published: 02/06/2003
• Est. Priority Date: 02/25/2000
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Nishinaga, Hisashi
• Granted Patent: US 6,771,350 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• CPC Class Codes: G03B 27/42 for automatic sequential copying of the same original G03B27/34, G03B27/53 take precedence
• CPC Class Codes: G03F 7/70083 Non-homogeneous intensity distribution in the mask plane
• CPC Class Codes: G03F 7/701 Off-axis setting using an aperture
• CPC Class Codes: G03F 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like

Abstract

An exposure apparatus radiates an exposure light beam from an exposure light source onto a reticle via an illumination optical system including a first fly'"'"'s eye lens, a second fly'"'"'s eye lens, a lens system, a blind, and a condenser lens system, and it projects an image of a pattern on the reticle onto a wafer via a projection optical system. An illumination characteristic is measured by using an evaluation mark plate on a reticle stage and a spatial image-measuring system provided for a wafer stage. The states of the second fly'"'"'s eye lens and the lens system are adjusted by the aid of a driving unit on the basis of the measured value. A concentration filter plate, which is formed with a pattern of a predetermined transmittance distribution, is rotatably arranged in the vicinity of a conjugate plane with respect to an image plane between the second lens system and the blind. The angle of rotation of the concentration filter plate 51 is controlled so that the uneven illuminance is corrected. The illumination optical system can be adjusted correctly for a short period of time. It is possible to improve the uniformity of the exposure amount distribution.

Claims

1. An exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising:

an illumination system which is provided with an optical member and which illuminates the first object with the exposure light beam;

an illumination condition-switching system which is arranged in the illumination system and which switches an illumination condition of the first object with the exposure light beam; and

an adjusting system which adjusts a state of the optical member in the illumination system in order to control an illumination characteristic of the illumination system depending on the switched illumination condition.

2. The exposure apparatus according to claim 1, wherein the adjusting system includes a driving system which moves the optical member, and a control system which controls the driving system depending on the switched illumination condition.

3. The exposure apparatus according to claim 1, wherein the illumination characteristic is at least one of uneven illuminance of the exposure light beam and a collapse amount of a telecentric property of the exposure light beam.

4. The exposure apparatus according to claim 3, wherein the uneven illuminance of the exposure light beam includes an inclination component and a concave/convex component, and the collapse amount of the telecentric property of the exposure light beam includes an inclination component and a magnification component.

5. The exposure apparatus according to claim 2, further comprising a characteristic-measuring system which measures the illumination characteristic of the illumination system, wherein the control system determines and stores a relationship between a driving amount of the driving system and an amount of change of the illumination characteristic on the basis of a result of the measurement performed by the characteristic-measuring system.

6. The exposure apparatus according to claim 2, wherein the optical member includes an optical integrator, and the driving system adjusts a position of the optical integrator in an optical axis direction.

7. The exposure apparatus according to claim 6, wherein the optical member further includes a first optical system and a second optical system which introduce the exposure light beam passed through the optical integrator into an irradiation plane of the first object or a plane conjugate therewith, and the driving system adjusts at least one of the position of the optical integrator in the optical axis direction, a position of the first optical system in the optical axis direction, and a position and a tilt angle of the second optical system in a direction perpendicular to an optical axis.

8. The exposure apparatus according to claim 7, wherein the illumination system further includes an optical element which sets an illuminance distribution of the exposure light beam to a local area for modified illumination, and a light-collecting optical system which introduces the exposure light beam from the optical element, and the adjusting system also adjusts a state of an optical member which constructs the light-collecting optical system.

9. The exposure apparatus according to claim 8, wherein the optical element is a diffractive optical element.

10. The exposure apparatus according to claim 8, wherein the illumination system includes a beam-shaping optical system which shapes the exposure light beam from an exposure light source to introduce the exposure light beam into the optical element, and the adjusting system adjusts a state of the beam-shaping optical system so that magnitude of illuminance of the exposure light beam and magnitude of dispersion of the illuminance distribution of the exposure light beam are balanced.

11. An exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising:

an illumination system which is provided with an optical member and which illuminates the first object with the exposure light beam;

a characteristic-measuring system which measures an illumination characteristic of the illumination system; and

an adjusting system which adjusts a state of the optical member in accordance with a result of the measurement performed by the characteristic-measuring system.

12. The exposure apparatus according to claim 11, further comprising a driving system which moves the optical member, and a storage unit which previously stores an amount of variation of the illumination characteristic depending an amount of movement of the optical member moved by the driving system.

13. The exposure apparatus according to claim 11, wherein the optical member includes an optical integrator, and the adjusting system adjusts a position of the optical integrator in an optical axis direction.

14. The exposure apparatus according to claim 13, wherein the optical member further includes a first optical system and a second optical system which introduce the exposure light beam passed through the optical integrator into an irradiation plane of the first object or a plane conjugate therewith, and the adjusting system adjusts at least one of the position of the optical integrator in the optical axis direction, a position of the first optical system in the optical axis direction, and a position and a tilt angle of the second optical system in a direction perpendicular to an optical axis.

15. The exposure apparatus according to claim 14, wherein:

the illumination system further includes an optical element which sets an illuminance distribution of the exposure light beam to a local area for modified illumination; and

a light-collecting optical system which introduces the exposure light beam from the optical element, and wherein;

the optical integrator uniformizes the illuminance distribution of the exposure light beam from the light-collecting optical system, and the adjusting system adjusts a state of an optical member which constructs the light-collecting optical system.

16. The exposure apparatus according to claim 15, wherein the illumination system includes a beam-shaping optical system which shapes the exposure light beam from an exposure light source to introduce the exposure light beam into the optical element, and the adjusting system adjusts a state of the beam-shaping optical system so that magnitude of illuminance of the exposure light beam and magnitude of dispersion of the illuminance distribution of the exposure light beam are balanced.

17. An exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising:

an illumination system which illuminates the first object with the exposure light beam;

a characteristic-measuring system which measures an illumination characteristic of the illumination system; and

a control system which independently determines a magnification component and an inclination component of a collapse amount of a telecentric property of the exposure light beam from the illumination characteristic measured by the characteristic-measuring system.

18. The exposure apparatus according to claim 17, wherein the control system independently determines a concave/convex component and an inclination component of uneven illuminance of the exposure light beam afforded by the illumination system, from the illumination characteristic measured by the characteristic-measuring system.

19. An exposure method for exposing a second object with an exposure light beam from an illumination system via a first object, the exposure method comprising the steps of:

illuminating the first object with the exposure light beam;

measuring an illumination characteristic of the illumination system;

independently determining a magnification component and an inclination component of a collapse amount of a telecentric property of the exposure light beam from the measured illumination characteristic;

adjusting the illumination system on the basis of the determined magnification and the inclination components of the collapse amount of the telecentric property; and

exposing the second object with the exposure light beam from the adjusted illumination system via the first object.

20. The exposure method according to claim 19, further comprising the step of independently determining a concave/convex component and an inclination component of uneven illuminance of the exposure light beam afforded by the illumination system from the measured illumination characteristic.

21. The exposure method according to claim 19, wherein the second object is subjected to scanning exposure by synchronously moving the first object and the second object with respect to the exposure light beam.

46. A method for producing a device, comprising the step of transferring a device pattern onto a substrate by the exposure method as defined in claim 19.

48. The exposure method according to claim 21, further comprising the step of independently determining a concave/convex component of uneven illuminance of the exposure light beam afforded by the illumination system, and an inclination component in a non-scanning direction perpendicular to a scanning direction in which the first and second objects are moved during the scanning exposure, from the measured illumination characteristic.

22. A method for adjusting an exposure apparatus provided with an illumination system for illuminating a first object with an exposure light beam, for exposing a second object with the exposure light beam via the first object, the method comprising the steps of:

setting a predetermined optical member in the illumination system in a plurality of states to measure an illumination characteristic of the illumination system in each state;

determining a relationship between an amount of change of the state of the optical member and an amount of change of the illumination characteristic on the basis of a result of the measurement of the illumination characteristic; and

adjusting the state of the optical member in order to control the illumination characteristic on the basis of the determined relationship.

23. The method for adjusting the exposure apparatus according to claim 22, further comprising the step of storing the determined relationship.

24. The method for adjusting the exposure apparatus according to claim 23, wherein:

the illumination system has a plurality of selectable illumination conditions; and

the adjusting method further comprises the steps of;

determining and storing an optimum position of the optical member for each of the plurality of illumination conditions;

selecting the illumination condition of the illumination system; and

setting the optical member to the optimum position for the selected illumination condition.

25. An exposure method for exposing a second object with an exposure light beam via a first object, the exposure method comprising the step of irradiating the first object with the exposure light beam after adjusting an exposure apparatus by the adjusting method as defined in claim 24.

26. An exposure method for exposing a second object with an exposure light beam via a first object, the exposure method comprising the steps of:

radiating the exposure light beam onto the first object; and

controlling a transmittance distribution of the exposure light beam in a planer area traversing an optical axis of the exposure light beam in the vicinity of an exposure plane of the second object or in the vicinity of a plane conjugate with the exposure plane.

27. The exposure method according to claim 26, wherein the transmittance distribution is controlled by a filter with a predetermined transmittance distribution inserted in an optical path of the exposure light beam in the vicinity of the exposure plane of the second object or in the vicinity of the plane conjugate with the exposure plane.

28. The exposure method according to claim 26, wherein the transmittance distribution corrects unevenness of an exposure amount distribution for the second object.

29. The exposure method according to claim 28, wherein the transmittance distribution is controlled to give a concentric distribution.

30. The exposure method according to claim 28, wherein the transmittance distribution is controlled to have a distribution one-dimensionally in a predetermined direction.

31. The exposure method according to claim 30, wherein the transmittance distribution is controlled to have a combination of one-dimensional distributions in predetermined directions.

32. The exposure method according to claim 28, wherein the transmittance distribution is a distribution which changes one-dimensionally symmetrically about a center of an optical axis.

33. The exposure method according to claim 28, wherein the transmittance distribution is a distribution in which transmittance is increased or decreased as being farther separated from an optical axis.

34. The exposure method according to claim 26, wherein:

the first object and the second object are synchronously moved in a scanning direction when the second object is exposed; and

the transmittance distribution for the exposure light beam is controlled so that an exposure amount distribution, which is obtained by adding up an exposure amount of the exposure light beam for the second object in the scanning direction, is uniformized.

47. A method for producing a device, comprising the step of transferring a device pattern onto a substrate by the exposure method as defined in claim 26.

35. An exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising:

an illumination system which illuminates the first object with the exposure light beam; and

at least one filter which is arranged in the vicinity of an exposure plane of the second object or in the vicinity of a plane conjugate with the exposure plane on an optical path for the exposure light beam up to the second object and which has a predetermined transmittance distribution with respect to the exposure light beam.

36. The exposure apparatus according to claim 35, wherein:

the illumination system includes at least one optical integrator for uniformizing an illuminance distribution of the exposure light beam, and a field diaphragm for defining an illumination area on the first object of the exposure light beam from the optical integrator, and the filter is arranged on a plane in the vicinity of the field diaphragm or on a plane in the vicinity of an irradiation plane of the first object; and

the exposure apparatus further comprises a driving unit which moves the filter to predetermined arrangement.

37. The exposure apparatus according to claim 35, wherein the filter has a concentric transmittance distribution.

38. The exposure apparatus according to claim 35, wherein the filter has a predetermined transmittance distribution in a one-dimensional direction symmetrically with respect to an optical axis.

39. The exposure apparatus according to claim 35, wherein the filter is composed of first and second filters which have the same transmittance distribution in a one-dimensional direction symmetrically with respect to an optical axis respectively, and the exposure apparatus further comprises a driving unit which rotates the first and second filters in mutually opposite phases.

40. The exposure apparatus according to claim 36, further comprising:

a stage system which synchronously moves the first object and the second object in a scanning direction;

an exposure amount distribution-measuring unit which measures a distribution of added-up value in the scanning direction of an exposure amount of the exposure light beam on the second object; and

a control unit which controls the driving unit to change an angle of rotation of the filter in accordance with an exposure amount distribution measured by the distribution-measuring unit.

41. The exposure apparatus according to claim 36, wherein the filter is a light-transmissive substrate deposited with metal, which is selected depending on the transmittance distribution.

42. The exposure apparatus according to claim 35, wherein the exposure light beam has a wavelength of not more than 200 nm.

43. An exposure apparatus for illuminating a first object with an exposure light beam and exposing a second object with the exposure light beam via the first object, the exposure apparatus comprising:

an illumination optical system which is capable of illuminating the first object under a plurality of illumination conditions respectively and in which an illuminance distribution of the exposure light beam has an identical tendency for the plurality of illumination conditions respectively; and

an optical member which is arranged on an optical path for the exposure light beam up to the second object and which adjusts the illuminance distribution.

44. The exposure apparatus according to claim 43, wherein the illumination optical system is adjusted to have uneven illuminance in which the illuminance distribution is substantially symmetrical with respect to an optical axis of the illumination optical system.

45. The exposure apparatus according to claim 43, wherein the optical member includes at least one optical filter which is arranged separately from an exposure plane of the second object or a conjugate plane thereof and which has a predetermined transmittance distribution with respect to the exposure light beam.

49. An exposure method for illuminating a first object with an exposure light beam and exposing a second object with the exposure light beam via the first object, the exposure method comprising:

changing an illumination condition for the first object depending on a pattern to be transferred onto the second object;

adjusting an inclination component and a centro-symmetrical component of uneven illuminance or uneven exposure amount in an irradiation area of the exposure light beam, respectively; and

adjusting the centro-symmetrical component without adjusting the inclination component during a predetermined period after the adjustment of the uneven illuminance or uneven exposure amount.

50. The exposure method according to claim 49, wherein the first and second objects are relatively moved with respect to the exposure light beam respectively to perform scanning exposure for the second object with the exposure light beam via the first object, and the inclination component is adjusted in a non-scanning direction perpendicular to a scanning direction in which the first and second objects are moved, when the illumination condition is changed.

51. The exposure method according to claim 50, wherein the inclination component and the centro-symmetrical component are determined on the basis of an exposure amount distribution in the non-scanning direction obtained by adding up an exposure amount or an illuminance in the scanning direction in the irradiation area of the exposure light beam.

52. An exposure method for irradiating a first object with an exposure light beam via an illumination optical system and exposing a second object with the exposure light beam via the first object, the exposure method comprising:

detecting the exposure light beam on a predetermined plane on which the second object is arranged to measure an illumination characteristic including at least one of a distribution of exposure amount or illuminance in an irradiation area of the exposure light beam and a telecentricity of the illumination optical system;

moving at least one optical element of the illumination optical system on the basis of the measured illumination characteristic;

updating the measured illumination characteristic by means of calculation until the illumination characteristic is measured next time; and

moving the at least one optical element on the basis of the updated illumination characteristic.

53. The exposure method according to claim 52, wherein the exposure light beam, which is radiated onto a mark provided for a first movable member for holding the first object, is detected to measure the telecentricity of the illumination optical system.

54. The exposure method according to claim 52, wherein the first and second objects are relatively moved with respect to the exposure light beam to perform scanning exposure for the second object with the exposure light beam via the first object, and the illuminance or the exposure amount is added up in a scanning direction in which the first and second objects are moved during the scanning exposure in the irradiation area of the exposure light beam to determine an exposure amount distribution concerning a non-scanning direction perpendicular to the scanning direction.