Exposure method and apparatus, and semiconductor device manufactured using the method

• US 6,236,447 B1
• Filed: 08/27/1998
• Issued: 05/22/2001
• Est. Priority Date: 08/29/1997
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yamada, Yuichi, Kawahara, Atsushi
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): NGUYEN, HUNG
• Application Number:
  US09/141,141
• Time in Patent Office: 999 Days
• Field of Search: 355/30, 355/53, 355/67, 355/77, 355/50, 355/51, 355/52, 355/55, 250/548, 356/399, 356/401
• US Class Current: 355/53
• CPC Class Codes: G03F 9/7034 Leveling
• CPC Class Codes: G03F 9/7046 Strategy, e.g. mark, sensor or wavelength selection

Abstract

An exposure method for exposing a surface to be exposed via a projection optical system after a substrate moves stepwise in a direction perpendicular to an optical axis of the projection optical system to feed to a predetermined exposure position a plurality of shots on the substrate, in turn, in which at least one of a position and tilt of the surface to be exposed of a fed shot to be exposed in the direction of the optical axis is measured during the stepwise movement, and the surface to be exposed is brought to a position of a focal plane of the projection optical system on the basis of a measurement value. The method includes a step of obtaining, in advance, a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement and a deformation of a main body structure, in each shot, and a step of bringing the surface to be exposed for the shot to be exposed to the position of the focal plane on the basis of a correction result of the measurement, in each shot to be exposed, using the focus offset, in an exposure sequence.

Claims

1. An exposure method for exposing a surface to be exposed via a projection optical system after a substrate moves stepwise in a direction perpendicular to an optical axis of the projection optical system to feed to a predetermined exposure position a plurality of shots on the substrates, in turn, in which at least one of a position and tilt of the surface to be exposed of a fed shot to be exposed in the direction of the optical axis is measured during the stepwise movement, and the surface to be exposed is brought to a position of a focal plane of the projection optical system on the basis of a measurement value, said method comprising:

a step of obtaining, in advance, a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement and a deformation of a main body structure, in each shot; and

a step of bringing the surface to be exposed for the shot to be exposed to the position of the focal plane on the basis of a correction result of the measurement, in each shot to be exposed, using the focus offset, in an exposure sequence.

2. The method according to claim 1, wherein the focus offset is obtained on the basis of a measurement error resulting from an intra-chip step produced when a position of the surface to be exposed is measured at the exposure position.

3. The method according to claim 1, wherein start timings of the measurements in each shot to be exposed in the exposure sequence are synchronized with reference to a position of the shot to be exposed during the stepwise movement.

4. The method according to claim 1, further comprising:

a step of confirming a position of the surface to be exposed, which has already been set in focus, at a predetermined timing after the surface to be exposed is brought to the position of the focal plane of the projection optical system using the correction result, and before an exposure start; and

a step of determining whether or not correction driving is to be redone based on the confirmation result by discriminating a residual using a given threshold value.

5. An exposure method for exposing a surface to be exposed via a projection optical system after a substrate moves stepwise in a direction perpendicular to an optical axis of the projection optical system to feed to a predetermined exposure position a plurality of shots on the substrates, in turn, in which at least one of a position and tilt of the surface to be exposed of a fed shot to be exposed in the direction of the optical axis is measured during the stepwise movement, and the surface to be exposed is brought to a position of a focal plane of the projection optical system on the basis of a measurement value, said method comprising:

a step of obtaining, in advance, a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement; and

a step of bringing the surface to be exposed for the shot to be exposed to the position of the focal plane on the basis of a correction result of the measurement, in each shot to be exposed, using the focus offset and information regarding a relative positional relationship between the focal plane and the surface to be exposed upon deformation of a main body structure in the measurement in an exposure sequence.

6. The method according to claim 5, wherein the focus offset is obtained on the basis of a measurement error resulting from an intra-chip step produced when a position of the surface to be exposed is measured at the exposure position.

7. The method according to claim 5, further comprising obtaining the information regarding the relative positional relationship between the focal plane and the surface to be exposed upon deformation of the main body structure by measuring a pitching component of a posture of a stage.

8. The method according to claim 5, further comprising obtaining the information regarding the relative positional relationship between the focal plane and the surface to be exposed upon deformation of the main body structure by measuring a pitching amount in a direction of the stepwise movement direction, in advance.

9. The method according to claim 5, further comprising synchronizing start timings of the stepping measurements in each shot to be exposed in the exposure sequence with reference to a position of the shot to be exposed during the stepwise movement.

10. The method according to claim 5, further comprising:

a step of confirming a position of the surface to be exposed, which has already been set in focus, at a predetermined timing after the surface to be exposed is brought to the position of the focal plane of the projection optical system using the correction, and before an exposure start; and

a step of determining whether or not correction driving is to be redone based on the confirmation result by discriminating a residual using a given threshold value.

11. An exposure method for exposing a surface to be exposed via a projection optical system after a substrate moves stepwise in a direction perpendicular to an optical axis of the projection optical system to feed to a predetermined exposure position a plurality of shots on the substrate, in turn, in which at least one of a position and tilt of the surface to be exposed of a fed shot to be exposed in the direction of the optical axis is measured during the stepwise movement, and the surface to be exposed is brought to a position of a focal plane of the projection optical system on the basis of a measurement value, said method comprising:

a step of performing the measurement during the stepwise movement, in each shot, for a first wafer of a plurality of wafers to be subjected to an identical exposure process, and performing a position measurement of the surface to be exposed after the shot to be exposed is fed to the exposure position;

a step of obtaining and storing a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement and a deformation of a main body structure in each shot, using a measurement value obtained by the measurement during the stepwise movement and a measurement value obtained at the exposure position; and

a step of bringing the surface to be exposed of the shot to be exposed to the position of the focal plane on the basis of a correction result of the measurement, in each shot to be exposed, using the focus offset, for a second wafer and subsequent wafers.

12. The method according to claim 11, wherein the focus offset is obtained on the basis of a measurement error resulting from an intra-chip step produced when a position of the surface to be exposed is measured at the exposure position.

13. The method according to claim 11, further comprising:

a step of performing a measurement at the exposure position after the surface to be exposed is brought to the position of the focal plane of the projection optical system, using the correction result at a measurement point using the focus offset for the second wafer and subsequent wafers; and

a step of re-calculating the focus offset on the basis of the measurement result.

14. The method according to claim 11, further comprising:

a step of performing a measurement at the exposure position after the surface to be exposed is brought to the position of the focal plane of the projection optical system, using the correction result at a measurement point using the focus offset for the second wafer and subsequent wafers; and

a step of finely adjusting a position of the surface to be exposed.

15. An exposure apparatus comprising:

a projection optical system for projecting a pattern formed on a master disk onto a photosensitive substrate;

a stage which is moved stepwise along a direction perpendicular to an optical axis of said projection optical system while carrying the substrate to feed a plurality of shots on the substrate, in turn, to a predetermined exposure position;

focus measurement means for measuring at least one of a position and tilt of a surface to be exposed of the substrate in a direction of the optical axis at the exposure position;

focusing means for bringing the surface to be exposed to a position of a focal plane of said projection optical system;

means for obtaining, in advance, a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement and a deformation of a main body structure, in each shot; and

correction means for correcting a measurement value of the measurement using the focus offset in an exposure sequence before the measurement value is supplied to said focusing means.

16. The apparatus according to claim 15, wherein said means for obtaining the focus offset obtains the focus offset on the basis of a measurement error resulting from an intra-chip step produced when a position of the surface to be exposed is measured at the exposure position.

17. The apparatus according to claim 15, wherein measurement start timings upon executing the measurement using said focus measurement means are synchronized with reference to a stage position.

18. The apparatus according to claim 15, further comprising means for confirming a position of the surface to be exposed, which has already been set in focus, at a predetermined timing after the surface to be exposed is brought to the position of the focal plane of said projection optical system using the correction result, and before an exposure start, and for determining whether or not correction driving is to be redone based on the confirmation result, by discriminating a residual using a given threshold value.

19. An exposure apparatus comprising:

a projection optical system for projecting a pattern formed on a master disk onto a photosensitive substrate;

a stage which is moved stepwise along a direction perpendicular to an optical axis of said projection optical system while carrying the substrate to feed a plurality of shots on the substrate, in turn to a predetermined exposure position;

focus measurement means for measuring at least one of a position and tilt of a surface to be exposed of the substrate in a direction of the optical axis at the exposure position;

focusing means for bringing the surface to be exposed to a position of a focal plane of said projection optical system;

means for obtaining, in advance, a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement; and

correction means for correcting a measurement value of the measurement using the focus offset and information regarding a relative positional relationship between the focal plane and the surface to be exposed upon deformation of a main body structure in the measurement, before the measurement value is supplied to said focusing means in an exposure sequence.

20. The apparatus according to claim 19, wherein said means for obtaining the focus offset obtains the focus offset on the basis of a measurement error resulting from an intra-chip step produced when a position of the surface to be exposed is measured at the exposure position.

21. The apparatus according to claim 19, wherein said means for obtaining the information regarding the relative positional relationship between the focal plane and the surface to be exposed upon deformation of the main body structure comprises means for measuring a pitching component of a posture of said stage.

22. The apparatus according to claim 19, further comprising a table that stores pitching amounts in directions of the stepwise movement, which amounts are measured in advance, which is held as the relative positional relationship between the focal plane and the surface to be exposed upon deformation of the main body structure.

23. The apparatus according to claim 19, wherein measurement start timings upon executing the stepping measurement using said focus measurement means are synchronized with reference to a position of said stage.

24. The apparatus according to claim 19, further comprising means for confirming a position of the surface to be exposed, which has already been set in focus, at a predetermined timing after the surface to be exposed is brought to the position of the focal plane of said projection optical system, using the correction result of the measurement, and before an exposure start, and for determining whether or not correction driving is to be redone based on the confirmation result by discriminating a residual using a given threshold value.

25. A device manufacturing method comprising the steps of:

exposing a surface to be exposed via a projection optical system after a substrate moves stepwise in a direction perpendicular to an optical axis of the projection optical system to feed to a predetermined exposure position a plurality of shots on the substrate, in turn;

measuring at least one of a position and tilt of the surface to be exposed of a fed shot to be exposed in the direction of the optical axis during the stepwise movement;

obtaining, in advance, a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement and a deformation of a main body structure, in each shot;

bringing the surface to be exposed for the shot to be exposed to the position of the focal plane on the basis of a correction result of the measurement, in each shot to be exposed, using the focus offset, in an exposure sequence; and

manufacturing a device.

26. A device manufacturing method comprising the steps of:

exposing a surface to be exposed via a projection optical system after a substrate moves stepwise in a direction perpendicular to an optical axis of the projection optical system to feed to a predetermined exposure position a plurality of shots on the substrate, in turn;

measuring at least one of a position and tilt of the surface to be exposed of a fed shot to be exposed in the direction of the optical axis during the stepwise movement;

obtaining, in advance, a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement;

bringing the surface to be exposed for the shot to be exposed to the position of the focal plane on the basis of a correction result of the measurement, in each shot to be exposed, using the focus offset and information regarding a relative positional relationship between the focal plane and the surface to be exposed upon deformation of a main body structure in the measurement, in an exposure sequence; and

manufacturing a device.

27. A device manufacturing method comprising the steps of:

exposing a surface to be exposed via a projection optical system after a substrate moves stepwise in a direction perpendicular to an optical axis of the projection optical system to feed to a predetermined exposure position a plurality of shots on the substrate, in turn;

measuring at least one of a position and tilt of the surface to be exposed of a fed shot to be exposed in the direction of the optical axis during the stepwise movement;

performing the measurement during the stepwise movement, in each shot, for a first wafer of a plurality of wafers to be subjected to an identical exposure process, and performing a position measurement of the surface to be exposed after the shot to be exposed is fed to the exposure position;

obtaining and storing a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement and a deformation of a main body structure in each shot, using a measurement value obtained by the measurement during the stepwise movement and a measurement value obtained at the exposure position;

bringing the surface to be exposed of the shot to be exposed to the position of the focal plane on the basis of a correction result of the measurement, in each shot to be exposed, using the focus offset, for a second wafer and subsequent wafers; and

manufacturing a device.

28. An exposure method, in which at least one of a position and tilt of a surface to be exposed is measured while a substrate moves stepwise to a predetermined exposure position, said method comprising:

a step of obtaining a focus offset as a measurement error resulting from different measurement points for the measurement during the stepwise movement and a deformation of a main body structure; and

a step of bringing the surface to be exposed to a position of a focal plane on the basis of a correction result determined by using (i) the at least one of the position and tilt of the surface to be exposed and (ii) the focus offset.