EXPOSURE APPARATUS, EXPOSURE METHOD, AND DEVICE MANUFACTURING METHOD

• US 20090284717A1
• Filed: 05/11/2009
• Published: 11/19/2009
• Est. Priority Date: 05/13/2008
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Kanaya, Yuho
• Granted Patent: US 8,786,829 B2
• Time in Patent Office: Days
• US Class Current: 355/30
• CPC Class Codes: G03F 7/70341 Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply chemical composition of immersion liquids G03F7/2041
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position

Abstract

In an exposure apparatus of a liquid immersion exposure method, a liquid immersion area is formed on the upper surface of a wafer by liquid supplied in a space formed with a projection optical system, and on a moving table holding the wafer, a plurality of encoder heads is placed. Of the plurality of encoder heads, a controller measures positional information of the moving table within an XY plane using an encoder head which is outside a liquid immersion area. This allows a highly precise and stable measurement of positional information of the moving table.

Claims

1. An exposure apparatus, the apparatus comprising:

a movable body which holds a mounted object and substantially moves along a predetermined plane;

a liquid supply device which supplies liquid on a surface of at least one of the object and the movable body on which the object is mounted;

a pattern generation device including an optical system which has liquid supplied to a space formed with the surface of at least one of the object and the movable body, irradiates an energy beam on the object via the optical system and the liquid, and forms a pattern on the object; and

a measurement system which has a plurality of encoder heads each placed on a surface of the movable body, and out of the plurality of encoder heads, measures positional information of the movable body, based on measurement values of encoder heads located outside a liquid immersion area formed by the liquid.

2. The exposure apparatus according to claim 1 wherein

the plurality of encoder heads is placed outside an area on a surface of the movable body where the liquid immersion area may be formed by the movement of the movable body.

3. The exposure apparatus according to claim 1 wherein

the measurement system selects and uses an encoder head outside the liquid immersion area from the plurality of encoder heads, based on positional information of the movable body within the predetermined plane.

4. The exposure apparatus according to claim 3 wherein

the plurality of encoder heads is placed spaced apart at a separation distance larger than the width of the liquid immersion area.

5. The exposure apparatus according to claim 3 wherein

the movable body is made of a member having a rectangular shape in a planar view, and the plurality of encoder heads is placed in each of the four corners of the movable body.

6. The exposure apparatus according to claim 3 wherein

the movable body is made of a member having a rectangular shape in a planar view, and the plurality of encoder heads is placed along at least one of the four sides of the movable body.

7. The exposure apparatus according to claim 1 wherein

the plurality of encoder heads include a first and a second head whose measurement directions are in a first and a second direction, respectively, which are orthogonal to each other in the predetermined plane, whereby

the measurement system uses at least a total of three encoder heads including one each of the first and second heads.

8. The exposure apparatus according to claim 7 wherein

the grating section includes a first diffraction grating which covers a range where the first head may face and whose periodic direction is in the first direction and a second diffraction grating which covers a range where the second head may face and whose periodic direction is in the second direction.

9. The exposure apparatus according to claim 7 wherein

the grating section includes a two-dimensional grating which covers a range where the first and second heads may face and whose periodic direction is in the first and second directions.

10. The exposure apparatus according to claim 1 wherein

the plurality of encoder heads include a two-dimensional head whose measurement directions are in both a first and a second direction, which are orthogonal to each other in the predetermined plane, whereby

the measurement system uses at least two of the two-dimensional heads.

11. The exposure apparatus according to claim 10 wherein

the grating section includes a two-dimensional grating which covers a range where the two-dimensional head may face and whose periodic direction is in the first and second directions.

12. The exposure apparatus according to claim 1 wherein

the surface of the movable body is covered with a light transmission member which forms a substantially flush surface with the object with a small gap in between, and covers the plurality of encoder heads.

13. The exposure apparatus according to claim 1 wherein

of the plurality of encoder heads which are outside the liquid immersion area, the measurement system uses remaining encoder heads that exclude an encoder head which outputs abnormal positional information.

14. The exposure apparatus according to claim 1, the apparatus further comprising:

a drive system which drives the movable body based on positional information of the movable body within the predetermined plane.

15. A device manufacturing method, the method including:

exposing an object using the exposure apparatus according to claim 1; and

developing the object which has been exposed.

16. An exposure method in which an energy beam is irradiated on an object via an optical system and liquid, and a pattern is formed on the object, the method comprising:

a measurement process in which of a plurality of encoder heads that are placed on a surface where the object is mounted of a movable body that substantially moves along a predetermined plane, positional information of the movable body is measured based on measurement values of encoder heads that face a grating section placed in parallel with the predetermined plane and are located outside a liquid immersion area formed with the liquid.

17. The exposure method according to claim 16 wherein

in the measurement process, an encoder head outside the liquid immersion area from the plurality of encoder heads is selected and used, based on positional information of the movable body within the predetermined plane.

18. The exposure method according to claim 16 wherein

the plurality of encoder heads include a first and a second head whose measurement directions are in a first and a second direction, respectively, which are orthogonal to each other in the predetermined plane, whereby

in the measurement process, at least a total of three encoder heads including one each of the first and second heads are used.

19. The exposure method according to claim 16 wherein

the plurality of encoder heads include a two-dimensional head whose measurement directions are in both a first and a second direction, which are orthogonal to each other in the predetermined plane, whereby

in the measurement process, at least two of the two-dimensional heads are used.

20. The exposure method according to claim 16 wherein

in the measurement process, of the plurality of encoder heads which are outside the liquid immersion area, remaining encoder heads that exclude an encoder head which outputs abnormal positional information are used.

21. The exposure method according to claim 16, the method further comprising:

a drive process in which the movable body is driven based on positional information of the movable body within the predetermined plane.

22. A device manufacturing method, the method including:

a process in which a pattern is formed on the object by the exposure method according to claim 16; and

a process in which the object on which the pattern has been formed is developed.