Exposure method, exposure apparatus, and device manufacturing method

Patent metadata

Field	Value
Publication number	US-9477155-B2
Application number	US-201414462668-A
Country	US
Kind code	B2
Filing date	Aug 19, 2014
Priority date	Aug 25, 2009
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

Within area where of four heads installed on a wafer stage, heads included in the first head group and the second head group to which three heads each belong that include one head different from each other face the corresponding areas on a scale plate, the wafer stage is driven based on positional information which is obtained using the first head group, as well as obtain the displacement (displacement of position, rotation, and scaling) between the first and second reference coordinate systems corresponding to the first and second head groups using the positional information obtained using the first and second head groups. By using the results and correcting measurement results obtained using the second head group, the displacement between the first and second reference coordinate systems is calibrated, which allows the measurement errors that come with the displacement between areas on scale plates where each of the four heads face.

First claim

What is claimed is:

1. An exposure apparatus which exposes an object with an illumination light via a projection optical system, the apparatus comprising:
a stage having a holder configured to hold the object;
a driving system having an electromagnetic motor, which drives the stage by the electromagnetic motor, a part of the electromagnetic motor being provided at the stage;
an encoder system having a plurality of heads provided at the stage, which measures positional information of the stage by irradiating a measurement beam from below via each of the plurality of heads onto a measurement plane arranged substantially parallel to a predetermined plane perpendicular to an optical axis of the projection optical system; and
a controller coupled with the driving system and the encoder system, which controls a drive of the stage based on the measured positional information, wherein
the measurement plane is defined by a plurality of scale plates which are arranged around an exposure position where exposure of the object is performed via the projection optical system and on each of which a reflective grating is formed,
in a part including the exposure position, of a first movement area where the stage is moved in an exposure operation of the object, the encoder system is capable of measuring the positional information of the stage by the plurality of heads that respectively face the plurality of scale plates, and in another part of the first movement area, the encoder system is capable of measuring the positional information of the stage by remaining heads after excluding one head of the plurality of heads, and
the controller decides calibration information of the encoder system based on the positional information of the stage measured by the encoder system in the part including the exposure position of the first movement area.

2. The exposure apparatus according to claim 1 , wherein
in the part including the exposure position of the first movement area, the positional information of the stage can be measured by four heads of the encoder system, and in the another part of the first movement area, the positional information of the stage can be measured by three heads of the four heads.

3. The exposure apparatus according to claim 2 , wherein
in the another part of the first movement area, a combination of three heads used in the measurement, of the four heads, differs depending on a position of the stage.

4. The exposure apparatus according to claim 1 , wherein
in the part including the exposure position of the first movement area, the positional information measured by three heads of four heads of the encoder system is used in drive control of the stage, and
in the another part of the first movement area, the positional information measured by three heads, of the four heads, having one head different from the three heads used in the part including the exposure position is used in the drive control of the stage.

5. The exposure apparatus according to claim 4 , wherein
prior to a movement of the stage from the part including the exposure position to the another part in the first movement area, one head of the three heads used in the drive control of the stage is switched to another head that is different from the three heads of the four heads, and
after the switching, the positional information measured by three heads that are two heads different from the one head among the three heads before the switching and the another head is used in the drive control of the stage.

6. The exposure apparatus according to claim 5 , wherein
the calibration information is used for the drive control of the stage after the switching.

7. The exposure apparatus according to claim 5 , wherein
the plurality of scale plates each have a two-dimensional grating formed, and are provided at a metrology frame that holds the projection optical system, and
the plurality of heads are each capable of measuring the positional information of the stage in both of a direction parallel to the predetermined plane and a direction orthogonal to the predetermined plane.

8. The exposure apparatus according to claim 5 , further comprising:
a detection system having a detection position in a second movement area different from the first movement area, which detects positional information of the object, wherein
the encoder system measures the positional information of the stage that is moved in the second movement area in a detection operation of the object by the detection system, by irradiating the measurement beam from below via each of the plurality of heads onto another measurement plane that is different from the measurement plane and arranged substantially parallel to the predetermined plane, and
the another measurement plane is defined by different plurality of scale plates that are different from the plurality of scale plates and arranged around the detection position.

9. The exposure apparatus according to claim 8 , wherein
a part of the measurement plane is an opening, the part including the exposure position, and
a distance between two heads set apart in a first direction within the predetermined plane, of the plurality of heads, is larger than a width of the opening in the first direction.

10. The exposure apparatus according to claim 9 , wherein
the stage is moved so that a plurality of divided areas on the object are each exposed in the first movement area, and
the distance between the two heads in the first direction is larger than a sum of the width of the opening and a width of one of the plurality of divided areas in the first direction.

11. The exposure apparatus according to claim 10 , wherein
a distance between two heads set apart in a second direction orthogonal to the first direction within the predetermined plane, of the plurality of heads, is larger than a width of the opening in the second direction.

12. The exposure apparatus according to claim 11 , wherein
the stage is moved so that the plurality of divided areas on the object are each exposed in the first movement area, and
the distance between the two heads in the second direction is larger than a sum of the width of the opening and a width of one of the plurality of divided areas in the second direction.

13. The exposure apparatus according to claim 12 , wherein
the stage is moved so that scanning exposure of each of the plurality of divided areas on the object is performed in the first movement area, and in an exposure operation of the object, a movement of the stage in the first direction for the scanning exposure and a step movement of the stage in the second direction are performed, and
the distance between the two heads in the first direction is larger than a sum of the width of the opening and twice a distance of the step movement in the first direction.

14. The exposure apparatus according to claim 8 , wherein
the stage is moved so that scanning exposure of each of a plurality of divided areas on the object is performed in the first movement area, and
in the another part of the first movement area, a combination of the remaining heads used in measurement of the positional information of the stage, of the plurality of heads, differs depending on a position of the stage, and the combination of the remaining heads is changed at a time other than a scanning exposure period of the divided area.

15. The exposure apparatus according to claim 14 , wherein
the combination of the remaining heads is changed before the scanning exposure of the divided area is started or after the scanning exposure of the divided area is completed.

Assignees

• Nikon Corp

Inventors

• Shibazaki Yuichi

Classifications

• H10P72/53

  using optical controlling means · CPC title

• G03F9/70

  for microlithography (measuring printed patterns for monitoring overlay G03F7/70633 or focus G03F7/70641; projection system adjustment G03F7/70258; position control G03F7/70775) · CPC title

• G03F7/20 Primary

  Exposure; Apparatus therefor (photographic printing apparatus for making copies G03B27/00) · CPC title

• G03F7/70483

  Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring · CPC title

• Y10T29/49002

  Electrical device making · CPC title