U.S. patent application number 13/324334 was filed with the patent office on 2012-04-12 for detection device, movable body apparatus, pattern formation apparatus and pattern formation method, exposure apparatus and exposure method, and device manufacturing method.
This patent application is currently assigned to NIKON CORPORATION. Invention is credited to Yuho KANAYA.
Application Number | 20120086927 13/324334 |
Document ID | / |
Family ID | 39720487 |
Filed Date | 2012-04-12 |
United States Patent
Application |
20120086927 |
Kind Code |
A1 |
KANAYA; Yuho |
April 12, 2012 |
DETECTION DEVICE, MOVABLE BODY APPARATUS, PATTERN FORMATION
APPARATUS AND PATTERN FORMATION METHOD, EXPOSURE APPARATUS AND
EXPOSURE METHOD, AND DEVICE MANUFACTURING METHOD
Abstract
By irradiating a detection beam from an irradiation system of a
detection device to a scale used for measuring the position of a
wafer stage, and detecting the detection beam via the scale by a
photodetection system, a surface state (an existence state of
foreign substance) of the scale is detected. With this operation,
detection of the surface state can be performed contactlessly with
respect to the scale. Moreover, movement control of the wafer stage
can be performed with high precision by taking the surface state
into consideration.
Inventors: |
KANAYA; Yuho; (Kumagaya-shi,
JP) |
Assignee: |
NIKON CORPORATION
Tokyo
JP
|
Family ID: |
39720487 |
Appl. No.: |
13/324334 |
Filed: |
December 13, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12128036 |
May 28, 2008 |
8098362 |
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13324334 |
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60924736 |
May 30, 2007 |
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Current U.S.
Class: |
355/30 ; 355/53;
355/77; 356/237.2; 356/616 |
Current CPC
Class: |
G03F 7/70775 20130101;
G03F 7/70925 20130101; G03F 7/70916 20130101; G03F 7/70341
20130101; G03F 7/7085 20130101 |
Class at
Publication: |
355/30 ;
356/237.2; 356/616; 355/53; 355/77 |
International
Class: |
G03B 27/52 20060101
G03B027/52; G01B 11/14 20060101 G01B011/14; G01N 21/88 20060101
G01N021/88 |
Claims
1. A detection device that detects a surface state of a measurement
member which is arranged on a movable body and to which a
measurement beam used for measurement of positional information of
the movable body in a predetermined direction is irradiated, the
detection device comprising: an irradiation system that irradiates
a light beam to the measurement member; and a detection system that
detects the light beam via the measurement member.
2. The detection device according to claim 1, wherein the
measurement member is configured of a grating member that has a
grating having a periodic direction in the predetermined direction,
and the detection system detects a surface state of the grating
member by detecting the light beam.
3. The detection device according to claim 2, wherein the
irradiation system irradiates the light beam substantially parallel
to the grating member.
4. The detection device according to claim 2, wherein the
irradiation system irradiates the light beam and forms a
band-shaped irradiation area that is elongated in a direction
intersecting the predetermined direction on the grating member.
5. The detection device according to claim 4, wherein the detection
system detects a coordinate of an irradiation position on the
grating member of the light beam received by the detection
system.
6. The detection device according to claim 2, wherein the surface
state of the grating member includes whether or not a foreign
substance exists on a surface of the grating member.
7. The detection device according to claim 1, wherein the
irradiation system irradiates the light beam substantially parallel
to a surface of the measurement member.
8. The detection device according to claim 1, wherein the
irradiation system irradiates the light beam and forms a
band-shaped irradiation area that is elongated in a direction
intersecting the predetermined direction on the measurement
member.
9. The detection device according to claim 1, wherein the surface
state of the measurement member includes whether or not a foreign
substance exists on a surface of the measurement member.
10. A movable body apparatus, comprising: a movable body on which a
measurement member is arranged; a measurement device that has a
head facing the measurement member and measures positional
information of the movable body in the predetermined direction by
the head; and the detection device according to claim 1 that
detects a surface state of the measurement member.
11. A pattern formation apparatus, comprising: the movable body
apparatus according to claim 10 in which the movable body holds an
object; and a pattern generation device that generates a pattern on
the object.
12. The pattern formation apparatus according to claim 11, wherein
the detection device has a plurality of irradiation areas of the
light beam, and at least one of the plurality of irradiation areas
is placed at a position where detection of a surface state of the
measurement member can be performed, while the movable body is
performing an operation including movement for pattern formation on
the object.
13. The pattern formation apparatus according to claim 12, wherein
the detection device has a plurality of irradiation areas of the
light beam, and at least one of the plurality of irradiation areas
is placed at a position where detection of a surface state of the
measurement member can be performed, while the movable body is
performing an operation including movement for detection of a mark
placed on the object.
14. The pattern formation apparatus according to claim 12, wherein
the detection device has a plurality of irradiation areas of the
light beam, and at least one of the plurality of irradiation areas
is placed at a position where detection of a surface state of the
measurement member can be performed, while the movable body is
performing an operation including movement from a position where an
object is unloaded from the movable body to a position where an
object is loaded to the movable body.
15. The pattern formation apparatus according to claim 12, wherein
the surface state of the measurement member includes whether or not
a foreign substance exists on a surface of the measurement
member.
16. The pattern formation apparatus according to claim 15, further
comprising: a foreign substance removal device that removes a
foreign substance existing on the surface of the measurement member
based on a detection result of the detection device.
17. The pattern formation apparatus according to claim 16, wherein
the pattern generation device has an optical member that is placed
facing the object and emits an energy beam, and a liquid immersion
system that fills a space between the optical member and the object
with a liquid and forms a liquid immersion area, and the foreign
substance removal device includes the liquid immersion system.
18. The pattern formation apparatus according to claim 17, wherein
the liquid immersion system uses a liquid that is different from
the liquid that forms the liquid immersion area, when removing the
foreign substance.
19. The pattern formation apparatus according to claim 12, further
comprising: a warning device that issues a warning in accordance
with a detection result of the detection device.
20. The pattern formation apparatus according to claim 12, further
comprising: another movable body that is different from the movable
body, wherein the detection device also detects a surface state of
a measurement member arranged on the another movable body.
21. The pattern formation apparatus according to claim 12, wherein
a surface of the movable body on a side of holding the object and
the surface of the measurement member are set flush with a surface
of the object held by the movable body.
22. The pattern formation apparatus according to claim 12, wherein
the pattern generation device exposes an object with an energy beam
and forms a pattern on the object.
23. An exposure apparatus that exposes an object with an energy
beam and forms a pattern on the object, the apparatus comprising:
the movable body apparatus according to claim 11 in which the
movable body holds the object.
24. The exposure apparatus according to claim 23, wherein a surface
of the movable body on a side of holding the object and a surface
of the measurement member are set flush with a surface of the
object held by the movable body.
25. The exposure apparatus according to claim 23, further
comprising: an optical member that is placed facing the object; and
a liquid immersion system that fills a space between the optical
member and the object with a liquid and forms a liquid immersion
area, wherein the liquid immersion area passes on the measurement
member during movement of the movable body.
26. A movable body apparatus, comprising: a movable body on which a
measurement member is arranged; a measurement device that has a
head that irradiates a measurement beam to the measurement member
when facing the measurement member and receives the measurement
beam via the measurement member, and measures positional
information of the movable body in a predetermined direction by the
head; and a detection device that detects a surface state of the
measurement member.
27. The movable body apparatus according to claim 26, wherein the
measurement member is configured of a grating member that has a
grating having a periodic direction in the predetermined direction,
and the detection device detects a surface state of the grating
member.
28. The movable body apparatus according to claim 27, wherein the
grating member has a first plate-shaped member on which the grating
is formed and a second plate-shaped member that is attached to the
first plate-shaped member in a state of covering the grating
section on the first plate-shaped member.
29. The movable body apparatus according to claim 27, wherein on
the movable body, a grating member on which a first grating is
formed with a direction parallel to a first axis serving as the
predetermined direction and a grating member on which a second
grating is formed with a direction parallel to a second axis that
intersects the first axis serving as the predetermined direction
are arranged, and the measurement device includes a first axis
encoder that has a plurality of first heads whose positions are
different in a direction intersecting the direction parallel to the
first axis and measures positional information of the movable body
in the direction parallel to the first axis by the first head
facing the first grating, and a second axis encoder that has a
plurality of second heads whose positions are different in a
direction intersecting the direction parallel to the second axis
and measures positional information of the movable body in the
direction parallel to the second axis by the second head facing the
second grating.
30. The movable body apparatus according to claim 29, wherein the
detection device has an irradiation area of the light beam used to
detect a surface state of the grating member on which the first
grating is formed, and an irradiation area of the light beam used
to detect a surface state of the grating member on which the second
grating is formed.
31. The movable body apparatus according to claim 27, wherein the
detection device has an irradiation system that irradiates a light
beam to the grating member, and a detection system that detects the
light beam via the grating member.
32. The movable body apparatus according to claim 31, wherein the
irradiation system irradiates the light beam substantially parallel
to a surface of the grating member.
33. The movable body apparatus according to claim 31, wherein the
irradiation system irradiates the light beam and forms a
band-shaped irradiation area that is elongated in a direction
intersecting the predetermined direction on the grating member.
34. The movable body apparatus according to claim 33, wherein the
detection system detects a coordinate of an irradiation position on
the grating member of the light beam received by the detection
system.
35. The movable body apparatus according to claim 33, further
comprising: a controller that changes a relative position in the
predetermined direction of the irradiation area and the grating
member, in parallel with detection by the detection device.
36. The movable body apparatus according claim 35, wherein the
controller performs the change of the relative position by movement
of the movable body.
37. A pattern formation apparatus, comprising: the movable body
apparatus according to claim 27 in which the movable body holds an
object; and a pattern generation device that generates a pattern on
the object.
38. The pattern formation apparatus according to claim 37, wherein
the detection device has a plurality of irradiation areas of the
light beam, and at least one of the plurality of irradiation areas
is placed at a position where detection of a surface state of the
grating member can be performed, while the movable body is
performing an operation including movement for pattern formation on
the object.
39. The pattern formation apparatus according to claim 37, wherein
the detection device has a plurality of irradiation areas of the
light beam, and at least one of the plurality of irradiation areas
is placed at a position where detection of a surface state of the
grating member can be performed, while the movable body is
performing an operation including movement for detection of a mark
placed on the object.
40. The pattern formation apparatus according to claim 37, wherein
the detection device has a plurality of irradiation areas of the
light beam, and at least one of the plurality of irradiation areas
is placed at a position where detection of a surface state of the
grating member can be performed, while the movable body is
performing an operation including movement from a position where an
object is unloaded from the movable body to a position where an
object is loaded to the movable body.
41. The pattern formation apparatus according to claim 37, wherein
the surface state of the grating member includes whether or not a
foreign substance exists on a surface of the grating member.
42. The pattern formation apparatus according to claim 41, further
comprising: a foreign substance removal device that removes a
foreign substance existing on the surface of the grating member
based on a detection result of the detection device.
43. The pattern formation apparatus according to claim 42, wherein
the pattern generation device has an optical member that is placed
facing the object and emits an energy beam, and a liquid immersion
system that fills a space between the optical member and the object
with a liquid and forms a liquid immersion area, and the foreign
substance removal device includes the liquid immersion system.
44. The pattern formation apparatus according to claim 43, wherein
the liquid immersion system uses a liquid that is different from
the liquid that forms the liquid immersion area, when removing the
foreign substance.
45. The pattern formation apparatus according to claim 37, further
comprising: a selection device that judges whether to perform
cleaning of the grating member or to continue a series of
operations by the movable body for pattern formation on the object
based on a detection result of the detection device, and in the
case where the series of operations is continued, selects a head of
the measurement device avoiding a foreign substance so that a head
that faces the foreign substance is not used during the series of
operations.
46. The pattern formation apparatus according to claim 37, further
comprising: a warning device that issues a warning in accordance
with a detection result of the detection device.
47. The pattern formation apparatus according to claim 37, further
comprising: another movable body that is different from the movable
body, wherein the detection device also detects a surface state of
a grating member arranged on the another movable body.
48. The pattern formation apparatus according to claim 37, wherein
a surface of the movable body on a side of holding the object and
the surface of the grating member are set flush with a surface of
the object held by the movable body.
49. The pattern formation apparatus according to claim 37, wherein
the pattern generation device exposes an object with an energy beam
and forms a pattern on the object.
50. An exposure apparatus that exposes an object with an energy
beam and forms a pattern on the object, the apparatus comprising:
the movable body apparatus according to claim 27 in which the
movable body holds the object.
51. The exposure apparatus according to claim 50, wherein a surface
of the movable body on a side of holding the object and a surface
of the grating member are set flush with a surface of the object
held by the movable body.
52. The exposure apparatus according to claim 50, further
comprising: an optical member that is placed facing the object; and
a liquid immersion system that fills a space between the optical
member and the object with a liquid and forms a liquid immersion
area, wherein the liquid immersion area passes on the grating
member during movement of the movable body.
53. A movable body apparatus, comprising: a movable body that moves
within a predetermined plane, holding an object mounted on the
movable body; a measurement device that has a head that faces one
surface of the movable body on which the object is mounted and
which is parallel to the plane, and measures positional information
of the movable body in a predetermined direction by the head
irradiating a measurement beam to an area other than a mounting
area of the object on the one surface of the movable body; and a
detection device that detects a surface state of the area other
than the mounting area of the object on the one surface of the
movable body.
54. A pattern formation apparatus, comprising: the movable body
apparatus according to claim 53; and a pattern generation device
that generates a pattern on an object mounted on the movable
body.
55. The pattern formation apparatus according to claim 54, wherein
the pattern generation device forms a pattern on the object by
irradiating an energy beam and exposing the object.
56. A pattern formation method, comprising: a pattern formation
process of forming a pattern on an object held by a movable body;
and a detection process of detecting a surface state of a
measurement member which is arranged on the movable body and to
which a measurement beam used for measurement of positional
information of the movable body in a predetermined direction is
irradiated.
57. The pattern formation method according to claim 56, wherein in
the detection process, a surface state of a grating member on which
a grating having a periodic direction in the predetermined
direction is formed is detected.
58. The pattern formation method according to claim 57, wherein in
the detection process, a light beam is irradiated to a surface of
the grating member and the light beam via the surface of the
grating member is detected.
59. The pattern formation method according to claim 58, wherein in
the detection process, the light beam is irradiated substantially
parallel to the surface of the grating member.
60. The pattern formation method according to claim 57, wherein in
the pattern formation process, a position of the movable body is
detected using the grating of the grating member.
61. The pattern formation method according to claim 57, wherein at
least part of processing of the detection process is performed in
parallel with processing of the pattern formation process.
62. The pattern formation method according to claim 57, further
comprising: a mark detection process of detecting a mark placed on
the object, prior to the pattern formation process, wherein at
least part of processing of the detection process is performed in
parallel with processing of the mark detection process.
63. The pattern formation method according to claim 57, further
comprising: an unload process of unloading an object held by the
movable body; and a load process of loading an object to the
movable body, wherein at least part of processing of the detection
process is performed during transition from the unload process to
the load process.
64. The pattern formation method according to claim 57, wherein the
surface state of the grating member includes whether or not a
foreign substance exists on a surface of the grating member, and
the pattern formation method further comprises a foreign substance
removal process of removing a foreign substance on the surface of
the grating member in accordance with a detection result of the
detection process.
65. The pattern formation method according to claim 57, further
comprising: a warning process of issuing a warning in accordance
with a detection result of the detection process.
66. A device manufacturing method, comprising: a process of forming
a pattern on an object by the pattern formation method according to
claim 57; and a process of applying processing to the object on
which the pattern is formed.
67. A pattern formation method, comprising: a pattern formation
process of forming a pattern on an object held by a movable body;
and a foreign substance removal process of removing a foreign
substance existing on a surface of the measurement member which is
arranged on the movable body and to which a measurement beam used
for measurement of positional information of the movable body in a
predetermined direction is irradiated.
68. The pattern formation method according to claim 67, wherein the
measurement member is a grating member on which a grating having a
periodic direction in a predetermined direction is formed, and in
the foreign substance removal process, a foreign substance existing
on a surface of the grating member is removed.
69. The pattern formation method according to claim 67, wherein in
the pattern formation process, an energy beam is irradiated to the
object via an optical member placed facing the object and a liquid
filled in a space between the optical member and the object by a
liquid immersion system, and in the foreign substance removal
process, a foreign substance existing on the surface of the
measurement member is removed by the liquid of the liquid immersion
system.
70. The pattern formation method according to claim 67, further
comprising: a detection process of detecting a foreign substance on
the surface of the measurement member prior to the foreign
substance removal process.
71. The pattern formation method according to claim 70, wherein in
the detection process, a light beam is irradiated to the
measurement member and the light beam via the measurement member is
detected.
72. A device manufacturing method, comprising: a process of forming
a pattern on an object by the pattern formation method according to
claim 67; and a process of applying processing to the object on
which the pattern is formed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Division of application Ser. No. 12/128,036 filed
May 28, 2008, which claims the benefit of Provisional Application
No. 60/924,736 filed May 30, 2007. The disclosures of the prior
applications are hereby incorporated by reference herein in their
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to detection devices, movable
body apparatuses, pattern formation apparatuses and pattern
formation methods, exposure apparatuses and exposure methods, and
device manufacturing methods, and more particularly to a detection
device that detects a surface state of a measurement member, a
movable body apparatus that is equipped with the detection device,
a pattern formation apparatus that is equipped with the movable
body apparatus, a pattern formation method of forming a pattern on
an object held by a movable body, and an exposure apparatus and an
exposure method that expose the object with an energy beam, and a
device manufacturing method that uses the pattern formation method
described above.
[0004] 2. Description of the Background Art
[0005] Conventionally, in a lithography process for manufacturing
electron devices (microdevices) such as semiconductor devices
(integrated circuits or the like) and liquid crystal display
devices, exposure apparatuses such as a projection exposure
apparatus based on a step-and-repeat method (a so-called stepper)
and a projection exposure apparatus based on a step-and-scan method
(a so-called scanning stepper (which is also called a scanner) are
mainly used.
[0006] In these steppers, scanners or the like, in general,
position measurement of a stage that holds a substrate to be
exposed (e.g. a wafer) is performed using a laser interferometer
having a high resolution. However, the length of an optical path of
a beam of the laser interferometer is as long as around several
hundreds mm or more. Further, due to finer patterns to cope with
higher integration of semiconductor devices, position control
performance with higher precision of the stage has been required.
For such a reason, the short term fluctuation of measurement values
of the laser interferometer caused by temperature fluctuations (air
fluctuations) of the atmosphere on the beam path of the laser
interferometer is becoming unignorable now.
[0007] Accordingly, recently the technology, in which a linear
encoder whose measurement values have smaller short-term
fluctuation due to temperature fluctuations (air fluctuations) than
the laser interferometer is used, has been proposed (e.g. refer to
the pamphlet of International Publication No. 2007/097379 and the
corresponding U.S. Patent Application Publication No. 2008/0088843,
and the like). In the case where such a linear encoder is used, if
a foreign substance exists on a scale, there is the possibility
that measurement error occurs or measurement cannot be performed
due to the foreign substance.
SUMMARY OF THE INVENTION
[0008] The present invention was made under the circumstances
described above, and according to a first aspect of the present
invention, there is provided a first exposure apparatus that
exposes an object held by a movable body with an energy beam, the
apparatus comprising: an encoder system of which one of a
measurement member and a head member is arranged on the movable
body and the other of the members is arranged facing the movable
body, and which measures positional information of the movable body
using a plurality of heads of the head member that faces the
measurement member; and a detection device that detects information
on a surface state of the measurement member.
[0009] With this apparatus, since detection device detects
information on a surface state of the measurement member,
deterioration in measurement accuracy of the encoder system caused
by the surface state can be suppressed by taking into consideration
the surface state (such as the adherence state of foreign
substance) of the measurement member. Accordingly, measurement of
positional information of the movable body can be performed with
high accuracy, and high-precision exposure to an object held on the
movable body can be performed.
[0010] According to a second aspect of the present invention, there
is provided an exposure method of exposing an object held by a
movable body with an energy beam, the method comprising: a
measurement process of measuring positional information of the
movable body, using an encoder system of which one of a measurement
member and a head member is arranged on the movable body and the
other of the members is arranged facing the movable body, and which
measures the positional information using a plurality of heads of
the head member that faces the measurement member; and a detection
process of detecting information on a surface state of the
measurement member using a detection device.
[0011] With this method, since information on a surface state of
the measurement member is detected using the detection device in
the detection process, deterioration in measurement accuracy of the
encoder system caused by the surface state can be suppressed by
taking into consideration the surface state (such as the adherence
state of foreign substance) of the measurement member. Accordingly,
measurement of positional information of the movable body can be
performed with high accuracy, and high-precision exposure to an
object held on the movable body can be performed.
[0012] According to a third aspect of the present invention, there
is provided a detection device that detects a surface state of a
measurement member which is arranged on a movable body and to which
a measurement beam used for measurement of positional information
of the movable body in a predetermined direction is irradiated, the
detection device comprising: an irradiation system that irradiates
a light beam to the measurement member; and a detection system that
detects the light beam via the measurement member.
[0013] With this device, it is possible to detect the surface state
contactlessly with respect to the measurement member.
[0014] According to a fourth aspect of the present invention, there
is provided a first movable body apparatus, comprising: a movable
body on which a measurement member is arranged; a measurement
device that has a head facing the measurement member and measures
positional information of the movable body in the predetermined
direction by the head; and the detection device of the present
invention that detects a surface state of the measurement
member.
[0015] With this apparatus, because the detection device detects
the surface state of the measurement member contactlessly with
respect to the measurement member, a detection operation of the
detection device does not hinder movement of the movable body.
Further, by taking into consideration the surface state (such as
the adherence state of foreign substance) of the measurement
member, deterioration in measurement accuracy of the measurement
device due to the surface state can be suppressed, which makes it
possible to perform high-precision movement control of the movable
body.
[0016] According to a fifth aspect of the present invention, there
is provided a first pattern formation apparatus, comprising: the
first movable body apparatus of the present invention in which the
movable body holds an object; and a pattern generation device that
generates a pattern on the object.
[0017] With this apparatus, position control of the movable body
(position control of an object) can be performed with high
accuracy, and therefore, by the pattern generation device
generating a pattern on the object held by the movable body,
high-precision pattern generation can be performed on the
object.
[0018] According to a sixth aspect of the present invention, there
is provided a second exposure apparatus that exposes an object with
an energy beam and forms a pattern on the object, the apparatus
comprising: the first movable body apparatus of the present
invention in which the movable body holds the object.
[0019] With this apparatus, because measurement of positional
information of the movable body can be performed with high
accuracy, a pattern can be formed with high accuracy on an, object
held by the movable body.
[0020] According to a seventh aspect of the present invention,
there is provided a second movable body apparatus, comprising: a
movable body on which a measurement member is arranged; a
measurement device that has a head that irradiates a measurement
beam to the measurement member when facing the measurement member
and receives the measurement beam via the measurement member, and
measures positional information of the movable body in a
predetermined direction by the head; and a detection device that
detects a surface state of the measurement member.
[0021] With this apparatus, the detection device detects the
surface state of the measurement member, and therefore, by taking
into consideration the surface state (such as the adherence state
of foreign substance) of the measurement member, deterioration in
measurement accuracy of the measurement device due to the surface
state can be suppressed. Accordingly, high-precision movement
control of the movable body can be performed.
[0022] According to an eight aspect of the present invention, there
is provided a second pattern formation apparatus, comprising: the
second movable body apparatus of the present invention in which the
movable body holds an object; and a pattern generation device that
generates a pattern on the object.
[0023] With this apparatus, position control of the movable body
(position control of an object) can be performed with high
accuracy, and therefore, by the pattern generation device
generating a pattern on the object held by the movable body,
high-precision pattern generation can be performed on the
object.
[0024] According to a ninth aspect of the present invention, there
is provided a third exposure apparatus that exposes an object with
an energy beam and forms a pattern on the object, the apparatus
comprising: the second movable body apparatus of the present
invention in which the movable body holds the object.
[0025] With this apparatus, because measurement of positional
information of the movable body can be performed with high
accuracy, a pattern can be formed with high accuracy on an object
held by the movable body.
[0026] According to a tenth aspect of the present invention, there
is provided a third movable body apparatus, comprising: a movable
body that moves within a predetermined plane, holding an object
mounted on the movable body; a measurement device that has a head
that faces one surface of the movable body on which the object is
mounted and which is parallel to the plane, and measures positional
information of the movable body in a predetermined direction by the
head irradiating a measurement beam to an area other than a
mounting area of the object on the one surface of the movable body;
and a detection device that detects a surface state of the area
other than the mounting area of the object on the one surface of
the movable body.
[0027] With this apparatus, the detection device detects the
surface state of an area other than a mounting area of an object on
one surface of the movable body, and therefore, by taking into
consideration the surface state (such as the adherence state of
foreign substance) of the area other than the mounting area of the
object on the one surface of the movable body to which a detection
beam from the measurement device is irradiated, deterioration in
measurement accuracy of the measurement device due to the surface
state can be suppressed. This makes it possible to perform
high-precision movement control of the movable body in a
predetermined direction.
[0028] According to an eleventh aspect of the present invention,
there is provided a third pattern formation apparatus, comprising:
the third movable body apparatus of the present invention; and a
pattern generation device that generates a pattern on an object
mounted on the movable body.
[0029] With this apparatus, position control of the movable body
(position control of an object) can be performed with high
accuracy, and therefore, by the pattern generation device
generating a pattern on the object held by the movable body,
high-precision pattern generation can be performed on the
object.
[0030] According to a twelfth aspect of the present invention,
there is provided a first pattern formation method, comprising: a
pattern formation process of forming a pattern on an object held by
a movable body; and a detection process of detecting a surface
state of a measurement member which is arranged on the movable body
and to which a measurement beam used for measurement of positional
information of the movable body in a predetermined direction is
irradiated.
[0031] With this method, pattern generation on the object can be
performed with high precision in a state where the influence by the
surface state (such as the adherence state of foreign substance) of
the measurement member is avoided.
[0032] According to a thirteenth aspect of the present invention,
there is provided a first device manufacturing method, comprising:
a process of forming a pattern on an object by the first pattern
formation method of the present invention; and a process of
applying processing to the object on which the pattern is
formed.
[0033] According to a fourteenth aspect of the present invention,
there is provided a second pattern formation method, comprising: a
pattern formation process of forming a pattern on an object held by
a movable body; and a foreign substance removal process of removing
a foreign substance existing on a surface of a measurement member
which is arranged on the movable body and to which a measurement
beam used for measurement of positional information of the movable
body in a predetermined direction is irradiated.
[0034] With this method, because the foreign substance existing on
the measurement member arranged on the movable body is removed in
the foreign substance removal process, a pattern can be formed on
the object without being affected by the foreign substance existing
on the measurement member in the pattern formation process.
[0035] According to a fifteenth aspect of the present invention,
there is provided a second device manufacturing method, comprising:
a process of forming a pattern on an object by the second pattern
formation method of the present invention; and a process of
applying processing to the object on which the pattern is
formed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] In the accompanying drawings;
[0037] FIG. 1 is a schematic view showing an exposure apparatus
related to an embodiment;
[0038] FIG. 2 is a plan view showing a stage device in FIG. 1;
[0039] FIG. 3 is a plan view showing the placement of various
measurement devices (such as encoders, alignment systems, and a
multipoint AF system) that are equipped in the exposure apparatus
in FIG. 1;
[0040] FIG. 4A is a perspective view showing a configuration of a
detection device in FIG. 3, and FIG. 4B is a view showing an
incident state of a detection beam emitted from a
light-transmitting system in FIG. 4 with respect to a scale;
[0041] FIG. 5 is a block diagram showing a main configuration of a
control system of the exposure apparatus related to the
embodiment;
[0042] FIGS. 6A and 6B are views used to explain position
measurement of a wafer stage within an XY plane by a plurality of
encoders each including a plurality of heads placed in the array
arrangement, and carryover of measurement values between the
heads;
[0043] FIG. 7A is a view showing an example of a configuration of
an encoder, and FIG. 7B is a view showing the case where a laser
beam LB having a sectional shape that is elongated in a periodic
direction of a grating RG is used as a detection light;
[0044] FIG. 8 is a view showing a state of the wafer stage and a
measurement stage when exposure based on a step-and-scan method is
being performed to a wafer on the wafer stage;
[0045] FIG. 9 is a view showing a state of the wafer stage and the
measurement stage when exposure to the wafer ends on the side of
the wafer stage;
[0046] FIG. 10 is a view showing a state of the wafer stage and the
measurement stage immediately after the state of both stages goes
from a state of separation to a state of coming into contact with
each other;
[0047] FIG. 11 is a view showing a state of the wafer stage and the
measurement stage when the measurement stage moves to a -Y
direction and the wafer stage moves toward an unloading position
while keeping the positional relation between both stages in a
Y-axis direction;
[0048] FIG. 12 is a view showing a state of the wafer stage and the
measurement stage when the measurement stage reaches a position
where Sec-BCHK (interval) is performed;
[0049] FIG. 13 is a view showing a state of the wafer stage and the
measurement stage when the wafer stage moves from the unloading
position to a loading position in parallel with the Sec-BCHK
(interval) being performed;
[0050] FIG. 14 is a view showing a state of the wafer stage and the
measurement stage when the measurement stage moves to an optimal
scrum waiting position and a wafer is loaded on the wafer
stage;
[0051] FIG. 15 is a view showing a state of the wafer stage and the
measurement stage when the wafer stage moves to a position where
the former process of Pri-BCHK is performed while the measurement
stage is waiting at the optimal scrum waiting position;
[0052] FIG. 16 is a view showing a state of the wafer stage and the
measurement stage when alignment marks arranged in three first
alignment shot areas are simultaneously being detected using
alignment system AL1, AL2.sub.2 and AL2.sub.3;
[0053] FIG. 17 is a view showing a state of the wafer stage and the
measurement stage when alignment marks arranged in five second
alignment shot areas are simultaneously being detected using
alignment system AL1, and AL2.sub.1 to AL2.sub.4;
[0054] FIG. 18 is a view showing a state of the wafer stage and the
measurement stage when alignment marks arranged in five third
alignment shot areas are simultaneously being detected using
alignment system AL1, and AL2.sub.1 to AL2.sub.4;
[0055] FIG. 19 is a view showing a state of the wafer stage and the
measurement stage when alignment marks arranged in three fourth
alignment shot areas are simultaneously being detected using
alignment system AL1, AL2.sub.2 and AL2.sub.3;
[0056] FIG. 20 is a view showing a state of the wafer stage and the
measurement stage when focus mapping ends; and
[0057] FIG. 21 is a view showing a state of the wafer stage and the
measurement stage during an exposure operation.
DESCRIPTION OF THE EMBODIMENTS
[0058] An embodiment of the present invention will be described
below, with reference to FIGS. 1 to 21.
[0059] FIG. 1 schematically shows a configuration of an exposure
apparatus 100 related to the embodiment. Exposure apparatus 100 is
a projection exposure apparatus based on a step-and-scan method,
that is, a scanner. As will be described later, in the embodiment,
a projection optical system PL is arranged, and the following
description will be made assuming that a direction parallel to an
optical axis AX of projection optical system PL is a Z-axis
direction, a direction in which a reticle and a wafer are
relatively scanned within a plane orthogonal to the Z-axis
direction is a Y-axis direction and a direction that is orthogonal
to a Z-axis and a Y-axis is an X-axis direction, and rotation
(tilt) directions around the X-axis, the Y-axis and the Z-axis are
.theta.x, .theta.y and .theta.z directions respectively.
[0060] Exposure apparatus 100 is equipped with an illumination
system 10, a reticle stage RST that holds a reticle R that is
illuminated by an illumination light for exposure (hereinafter,
referred to as an "illumination light" or an "exposure light") IL
from illumination system 10, a projection unit PU that includes
projection optical system PL that projects illumination light IL
emitted from reticle R on a wafer W, a stage device 50 that has a
wafer stage WST and a measurement stage MST, their control system,
and the like. On wafer stage WST, wafer W is mounted.
[0061] Illumination system 10 includes a light source and an
illumination optical system that has an illuminance uniformity
optical system containing an optical integrator and the like, and a
reticle blind and the like (none of which are shown), as is
disclosed in, for example, Kokai (Japanese Unexamined Patent
Application Publication) No. 2001-313250 (the corresponding U.S.
Patent Application Publication No. 2003/0025890) and the like. In
illumination system 10, a slit-shaped illumination area IAR that is
defined by the reticle blind (the masking system) on reticle R is
illuminated by illumination light (exposure light) IL with
substantially uniform illuminance. In this case, as illumination
light IL, an ArF excimer laser light (wavelength: 193 nm) is used
as an example. Further, as the optical integrator, for example, a
fly-eye lens, a rod integrator (an internal reflection type
integrator), a diffraction optical element or the like can be
used.
[0062] On reticle stage RST, reticle R having a pattern surface
(the lower surface in FIG. 1) on which a circuit pattern and the
like are formed is fixed by, for example, vacuum suction. Reticle
stage RST is finely drivable within an XY plane and also drivable
at designated scanning velocity in a scanning direction (which is
the Y-axis direction being a lateral direction of the page surface
of FIG. 1), by a reticle stage drive system 11 (not shown in FIG.
1, refer to FIG. 5) including, for example, a linear motor or the
like. Positional information of reticle stage RST is constantly
measured by a reticle interferometer 116.
[0063] Projection unit PU is placed below reticle stage RST in FIG.
1. Projection unit PU includes a barrel 40 and projection optical
system PL having a plurality of optical elements that are held in a
predetermined positional relation within barrel 40. As projection
optical system PL, for example, a dioptric system that is composed
of a plurality of lenses (lens elements) that are disposed along
optical axis AX direction parallel to the Z-axis direction is used.
Projection optical system PL is, for example, both-side telecentric
and has a predetermined projection magnification (e.g. one-quarter,
one-fifth, one-eighth times, or the like). Therefore, when
illumination area IAR is illuminated by illumination light IL from
illumination system 10, illumination light IL having passed through
reticle R whose pattern surface is placed substantially
coincidentally with a first surface (an object plane) of projection
optical system PL forms a reduced image of a circuit pattern (a
reduced image of part of a circuit pattern) of reticle R within
illumination area IAR on an area (hereinafter, also referred to as
an "exposure area") IA that is conjugate with illumination area IAR
on wafer W, which is placed on the second surface (the image plane)
side of projection optical system PL and whose surface is coated
with a resist (a photosensitive agent), via projection optical
system PL (projection unit PU). Although not shown in the drawing,
projection unit PU is mounted on a barrel platform that is
supported by three support columns via a vibration isolation
mechanism. However, the present invention is not limited thereto,
and as is disclosed in, for example, the pamphlet of International
Publication No. 2006/038952, projection unit PU may also be
supported in a suspended state with respect to a main frame member
(not shown) that is placed above projection unit PU, or a base
member on which reticle stage RST is placed, or the like.
[0064] Incidentally, in exposure apparatus 100 of the embodiment,
because exposure applying the liquid immersion method is performed,
a catadioptric system containing mirrors and lenses may also be
used, in order to satisfy the Petzval condition and also avoid the
increase in size of the projection optical system.
[0065] Further, in exposure apparatus 100 of the embodiment, in
order to perform exposure applying the liquid immersion method, a
nozzle unit 32 that constitutes part of a local liquid immersion
device 8 is arranged so as to enclose the periphery of the lower
end portion of barrel 40 that holds an optical element closest to
the image plane side (the wafer W side) that constitutes projection
optical system PL, which is a lens (hereinafter, also referred to a
"tip lens") 191 in this case. In the embodiment, as is shown in
FIG. 1, the lower end surface of nozzle unit 32 is set
substantially flush with the lower end surface of tip lens 191.
Further, nozzle unit 32 is equipped with a supply opening and a
recovery opening of a liquid Lq, a lower surface to which wafer W
is placed opposing and at which the recovery opening is arranged,
and a supply flow channel and a recovery flow channel that are
connected to a liquid supply pipe 31A and a liquid recovery pipe
31B respectively.
[0066] In the embodiment, the liquid is supplied from a liquid
supply device 5 (not shown in FIG. 1, refer to FIG. 5) to the space
between tip lens 191 and wafer W via liquid supply pipe 31A, the
supply flow channel and the supply opening, and the liquid is
recovered from the space between tip lens 191 and wafer W by a
liquid recovery device 6 (not shown in FIG. 1, refer to FIG. 5) via
the recovery opening, the recovery flow channel and liquid recovery
pipe 31B, so that a constant quantity of liquid Lq (refer to FIG.
1) is held in the space between tip lens 191 and wafer W. In this
case, liquid Lq held in the space between tip lens 191 and wafer W
is constantly replaced.
[0067] In the embodiment, as the liquid described above, pure water
(hereinafter, it will simply be referred to as "water" besides the
case where specifying is necessary) that transmits the ArF excimer
laser light (the light with a wavelength of 193 nm) is to be used.
Refractive index n of the water with respect to the ArF excimer
laser light is around 1.44. In the water the wavelength of
illumination light IL is 193 nm.times.1/n, shorted to around 134
nm.
[0068] As is obvious from the above description, in the embodiment,
local liquid immersion device 8 is configured including nozzle unit
32, liquid supply device 5, liquid recovery device 6, liquid supply
pipe 31A and liquid recovery pipe 31B, and the like. Incidentally,
part of local liquid immersion device 8, for example, at least
nozzle unit 32 may also be supported in a suspended state by a main
frame (including the barrel platform described above) that holds
projection unit PU, or may also be arranged at another frame member
that is separate from the main frame. Or, in the case where
projection unit PU is supported in a suspended state as is
described earlier, nozzle unit 32 may also be supported in a
suspended state integrally with projection unit PU, but in the
embodiment, nozzle unit 32 is arranged at a measurement frame that
is supported in a suspended state independently from projection
unit PU. In this case, projection unit PU does not have to be
supported in a suspended state.
[0069] Incidentally, also in the case where measurement stage MST
is located below projection unit PU, the space between the
measurement stage (to be described later) and tip lens 191 can be
filled with water in the similar manner to the above-described
manner.
[0070] Referring back to FIG. 1, stage device 50 is equipped with
wafer stage WST and measurement stage MST that are placed on a base
board 12, an interferometer system 118 (refer to FIG. 5) including
Y-axis interferometers 16 and 18 that measure positional
information of stages WST and MST, an encoder system 200 (refer to
FIG. 5) that is used to measure positional information of wafer
stage WST on exposure or the like, a stage drive system 124 (refer
to FIG. 5) that drives stages WST and MST, detection devices
PDX.sub.1 to PDX.sub.4, PDY.sub.1 and PDY.sub.2 (to be described
later, refer to the drawings such as FIGS. 3 and 5) and the
like.
[0071] On the bottom surface of each of wafer stage WST and
measurement stage MST, a noncontact bearing (not shown), for
example, a vacuum preload type hydrostatic air bearing
(hereinafter, referred to as an "air pad") is arranged at a
plurality of positions. Wafer stage WST and measurement stage MST
are supported in a noncontact manner via a clearance of around
several .mu.m above base board 12, by static pressure of
pressurized air that is blown out from the air pad toward the upper
surface of base board 12. Further, stages WST and MST are drivable
independently from each other at least in the Y-axis direction and
the X-axis direction by stage drive system 124.
[0072] On wafer stage WST, a wafer holder (not shown) that holds
wafer W by vacuum suction or the like is arranged. The wafer holder
may also be formed integrally with wafer stage WST, but in the
embodiment, the wafer holder and wafer stage WST are separately
configured, and the'wafer holder is fixed inside a recessed portion
of wafer stage WST, for example, by vacuum suction or the like.
Further, on the upper surface of wafer stage WST, a plate (liquid
repellent plate) 28 is arranged, which has the surface (the liquid
repellent surface) substantially flush with the surface of a wafer
mounted on the wafer holder to which liquid repellent treatment
with respect to liquid Lq is applied, has a rectangular outer shape
(contour), and has a circular opening that is formed in the center
portion and is slightly larger than the wafer holder (a mounting
area of the wafer). Plate 28 is made of materials with a low
coefficient of thermal expansion, for example, glasses or ceramics
(such as Zerodur (the brand name) of Schott AG, Al.sub.2O.sub.3, or
TiC), and on the surface of plate 28, a liquid repellent film is
formed by, for example, fluorine resin materials, fluorine series
resin materials such as polytetrafluoroethylene (Teflon (registered
trademark)), acrylic series resin materials, silicon series resin
materials, or the like. Further, as is shown in FIG. 2 that is a
plan view of stage device 50, plate 28 has a first liquid repellent
area 28a whose outer shape (contour) is rectangular enclosing the
circular opening, and a second liquid repellent area 28b that has a
rectangular frame (loop) shape placed on the periphery of first
liquid repellent area 28a. On first liquid repellent area 28a, for
example, when an exposure operation is performed, at least part of
a liquid immersion area 14 (e.g. refer to FIG. 3) protruding from
the surface of the wafer is formed, and on second liquid repellent
area 28b, scales for the encoder system (to be described later) are
formed. Incidentally, at least part of the surface of plate 28 does
not have to be flush with the surface of the wafer, that is, may be
different in height from the surface of the wafer. Further, plate
28 may be a single plate, but in the embodiment, plate 28 is
configured by combining a plurality of plates, for example, first
and second liquid repellent plates that correspond to first liquid
repellent area 28a and second liquid repellent area 28b
respectively. In the embodiment, pure water is used as liquid Lq as
is described above, and therefore hereinafter first liquid
repellent area 28a and second liquid repellent area 28b are also
referred to as first water repellent plate 28a and second water
repellent plate 28b respectively.
[0073] In this case, exposure light IL is irradiated to first water
repellent plate 28a on the inner side, while exposure light IL is
hardly irradiated to second water repellent plate 28b on the outer
side. Taking this fact into consideration, in the embodiment, a
first water repellent area to which water repellent coat having
sufficient resistance to exposure light IL (a light in a vacuum
ultraviolet region, in this case) is applied is formed on the
surface of first water repellent plate 28a, and a second water
repellent area to which water repellent coat having resistance to
exposure light IL inferior to the first water repellent area is
applied is formed on the surface of second water repellent plate
28b. Since it is difficult in general to apply water repellent coat
having sufficient resistance to exposure light IL (a light in a
vacuum ultraviolet region, in this case) to a glass plate, it is
effective to separate the water repellent plate into two sections
in this manner, i.e. first water repellent plate 28a and second
water repellent plate 28b on the periphery thereof. Incidentally,
the present invention is not limited thereto, and two types of
water repellent coat that have different resistance to exposure
light IL may also be applied on the upper surface of the same plate
in order to form the first water repellent area and the second
water repellent area. Further, the same kind of water repellent
coat may be applied to the first and second water repellent areas.
For example, only one water repellent area may also be formed on
the same plate.
[0074] Further, as is obvious from FIG. 2, at the end portion on
the +Y side of first water repellent plate 28a, a rectangular
cutout is formed in the center portion in the X-axis direction, and
a measurement plate 30 is embedded inside the rectangular space
(inside the cutout) that is enclosed by the cutout and second water
repellent plate 28b. A fiducial mark FM is formed in the center in
the longitudinal direction of measurement plate 30 (on a centerline
LL of wafer stage WST), and a pair of aerial image measurement slit
patterns SL (slit-shaped measurement patterns) are formed in the
symmetrical placement with respect to the center of fiducial mark
FM on one side and the other side in the X-axis direction of
fiducial mark FM. As each of aerial image measurement slit patterns
SL, an L-shaped slit pattern having sides along the Y-axis
direction and X-axis direction, or two linear slit patterns
extending in the X-axis direction and the Y-axis direction
respectively can be used, as an example. Inside wafer stage WST
below aerial image measurement slit patterns SL, an optical system
and the like that constitute an aerial image measurement device 45
(refer to FIG. 5) together with slit patterns SL are arranged.
[0075] As is shown in FIG. 7A, in actual, second water repellent
plate 28b is formed by two plate-shaped members 29a and 29b being
stuck together. On the upper surface (the surface on the +Z side)
of plate-shaped member 29b located on the lower side, many grating
lines of diffraction grating RG are arranged in a predetermined
pitch along each of the four sides of the surface. To be more
specific, as is shown in FIG. 2, in areas on one side and the other
side in the X-axis direction (on both sides in the vertical
direction in FIG. 2) of second water repellent plate 28b
(plate-shaped member 29b) Y scales 39Y.sub.1 and 39Y.sub.2 are
formed respectively. Each of Y scales 39Y.sub.1 and 39Y.sub.2 is
configured of, for example, a reflective grating (e.g. a
diffraction grating) having a periodic direction in the Y-axis
direction, in which the grating lines having the longitudinal
directions in the X-axis direction are formed in a predetermined
pitch along a direction parallel to the Y-axis (the Y-axis
direction). Similarly, in areas on one side and the other side in
the Y-axis direction (on both sides in the lateral direction in
FIG. 2) of second water repellent plate 28b, X scales 39X.sub.1 and
39X.sub.2 are formed respectively. Each of X scales 39X.sub.1 and
39X.sub.2 is configured of, for example, a reflective grating (e.g.
a diffraction grating) having a periodic direction in the X-axis
direction, in which the grating lines having the longitudinal
directions in the Y-axis direction are formed in a predetermined
pitch along a direction parallel to the X-axis (the X-axis
direction). In the embodiment, damage or the like of diffraction
grating RG can be prevented because second water repellent plate
28b is constituted by two plate-shaped members 29a and 29b as is
described above and plate-shaped member 29a on the upper side
covers diffraction grating RG. Incidentally, the pitch of the
grating is shown much wider in FIG. 2 than the actual pitch, for
the sake of convenience. The same is true also in other
drawings.
[0076] Mirror finish is severally applied to the -Y end surface and
the -X end surface of wafer stage WST, and a reflection surface 17a
and a reflection surface 17b shown in FIG. 2 are formed. By
severally projecting an interferometer beam (a measurement beam) to
reflection surface 17a and reflection surface 17b and receiving a
reflected light of each beam, Y-axis interferometer 16 and an
X-axis interferometer 126 (X-axis interferometer 126 is not shown
in FIG. 1, refer to FIG. 2) of interferometer system 118 (refer to
FIG. 5) measure a displacement of each reflection surface from a
reference position (generally, a fixed mirror is placed on the side
surface of projection unit PU, and the surface is used as a
reference surface), that is, positional information of wafer stage
WST within the XY plane, and the measurement values are supplied to
main controller 20. In the embodiment, as Y-axis interferometer 16
and x-axis interferometer 126, a multiaxial interferometer having a
plurality of measurement axes is used. Based on the measurement
values of Y-axis interferometer 16 and X-axis interferometer 126,
main controller 20 can also measure rotational information in the
.theta.x direction (i.e. pitching), rotational information in the
.theta.y direction (i.e. rolling) and rotational information in the
.theta.z direction (i.e. yawing), in addition to the X-position and
the Y-position of wafer stage WST. In the embodiment, however,
positional information of wafer stage WST within the XY plane
(including the rotational information in the .theta.z direction) is
mainly measured by each encoder of the encoder system (to be
described later) that uses the Y scales and the X scales described
above. And, the measurement values of interferometers 16 and 126
are secondarily used in the cases such as when long-term
fluctuation of the measurement values of each encoder (e.g. due to
deformation of the scales due to time passage, or the like) is
corrected (calibrated). Further, Y-axis interferometer 16 is used
to measure the Y-position of wafer stage WST and the like in the
vicinity of an unloading position and a loading position (to be
described later) for wafer exchange. Further, also for movement of
wafer stage WST, for example, between a loading operation and an
alignment operation and/or between an exposure operation and an
unloading operation, measurement information of interferometer
system 118, that is, at least one of positional information in
directions of five degrees of freedom (the X-axis, Y-axis,
.theta.x, .theta.y and .theta.z directions) is used. Incidentally,
at least part of interferometer system 118 (e.g. an optical system
or the like) may be arranged at the main frame that holds
projection unit PU, or may also be arranged integrally with
projection unit PU that is supported in a suspended state as is
described above, but, in the embodiment, interferometer system 118
is to be arranged at the measurement frame described above.
[0077] Incidentally, in the embodiment, as wafer stage WST, a
single stage that is movable in directions of six degrees of
freedom is employed, but as wafer stage WST, a configuration may
also be employed, which includes a stage main section that is
freely movable within the XY plane and a wafer table that is
mounted on the stage main section and is finely drivable in the
Z-axis direction, the .theta.x direction and .theta.y direction
relative to the stage main section. Further, instead of reflection
surface 17a and reflection surface 17b, a movable mirror composed
of a planar mirror may also be arranged at wafer stage WST.
Moreover, positional information of wafer stage WST is to be
measured with a reflection surface of the fixed mirror arranged at
projection unit PU serving as a reference surface, but the position
where the reference surface is placed is not limited to projection
unit PU, and positional information of wafer stage WST does not
necessarily have to be measured using the fixed mirror.
[0078] Further, in the embodiment, positional information of wafer
stage WST measured by interferometer system 118 is not used in the
exposure operation or the alignment operation (to be described
later) but is to be used mainly in the calibration operation (i.e.
calibration of measurement values) of each encoder or the like, but
measurement information of interferometer system 118 (i.e. at least
one of positional information in directions of five degrees of
freedom) may also be used in, for example, the operations such as
the exposure operation and/or the alignment operation. In the
embodiment, the encoder system measures positional information of
wafer stage WST in directions of three degrees of freedom, that is,
positional information in the X-axis, Y-axis and .theta.z
directions, using at least three encoders. Thus, in the operations
such as the exposure operation, among measurement information of
interferometer system 118, only positional information in a
direction different from the measurement directions (the X-axis,
Y-axis and .theta.z directions) of positional information of wafer
stage WST by the encoder may be used, or in addition to the
positional information in the different direction, positional
information in the same direction as the measurement directions of
the encoder (i.e. at least one of the X-axis, Y-axis and .theta.z
directions) may also be used. Further, interferometer system 118
may be capable of measuring positional information of wafer stage
WST in the Z-axis direction. In this case, the positional
information in the Z-axis direction may also be used in the
operations such as the exposure operation.
[0079] Measurement stage MST has various types of measurement
members and is drivable in directions of six degrees of freedom. As
the measurement members, for example, as is shown in FIG. 2, an
uneven illuminance measuring sensor 94 that has a pinhole-shaped
light-receiving section that receives illumination light IL on an
image plane of projection optical system PL, an aerial image
measuring instrument 96 that measures an aerial image (a projected
image) of a pattern that is projected by projection optical system
PL, and a wavefront aberration measuring instrument 98 based on the
Shack-Hartman method that is disclosed in, for example, the
pamphlet of International Publication No. 03/065428 and the like
are employed. As wavefront aberration measuring instrument 98, the
one disclosed in, for example, the pamphlet of International
Publication No. 99/60361 (the corresponding European Patent
Application Publication No. 1 079 223) can also be used.
[0080] As uneven illuminance measuring sensor 94, a configuration
similar to the one that is disclosed in, for example, Kokai
(Japanese Unexamined Patent Application Publication) No. 57-117238
(the corresponding U.S. Pat. No. 4,465,368) and the like can be
used. Further, as aerial image measuring instrument 96, a
configuration similar to the one that is disclosed in, for example,
Kokai (Japanese Unexamined Patent Application Publication) No.
2002-014005 (the corresponding U.S. Patent Application Publication
No. 2002/0041377) and the like can be used. Incidentally, three
measurement members (94, 96 and 98) are to be arranged at
measurement stage MST in the embodiment, however, the types and/or
the number of measurement members are/is not limited to them. As
the measurement members, for example, measurement members such as a
transmittance measuring instrument that measures a transmittance of
projection optical system PL, and/or a measuring instrument that
observes local liquid immersion device 8, for example, nozzle unit
32 (or tip lens 191) or the like may also be used. Furthermore,
members different from the measurement members such as a cleaning
member that cleans nozzle unit 32, tip lens 191 or the like may
also be mounted on measurement stage MST.
[0081] In addition to each of the sensors described above, an
illuminance monitor that has a light-receiving section having a
predetermined area size that receives illumination light IL on the
image plane of projection optical system PL may also be employed,
which is disclosed in, for example, Kokai (Japanese Unexamined
Patent Application Publication) No. 11-016816 (the corresponding
U.S. Patent Application Publication No. 2002/0061469) and the like,
and this illuminance monitor is also preferably placed on the
centerline.
[0082] Incidentally, in the embodiment, liquid immersion exposure
is performed in which wafer W is exposed with exposure light
(illumination light) IL via projection optical system PL and liquid
(water) Lq, and accordingly uneven illuminance measuring sensor 94
(and the illuminance monitor), aerial image measuring instrument 96
and wavefront aberration measuring instrument 98 that are used in
measurement using illumination light IL receive illumination light
IL via projection optical system PL and water. Further, only part
of each sensor, for example, the optical system or the like may be
mounted on measurement stage MST, or the entire sensor may be
placed on measurement stage MST.
[0083] On the side surface on the -Y side of measurement stage MST,
a confidential bar (hereinafter, shortly referred to as a "CD bar")
46 as a reference member having a rectangular parallelepiped shape
is arranged extending in the X-axis direction. CD bar 46 is
kinematically supported on measurement stage MST by full-kinematic
mount structure. Incidentally, CD bar 46 is also referred to as a
fiducial bar (shortly referred to as a "FD bar").
[0084] Since CD bar 46 serves as a prototype standard (a
measurement standard), optical glass ceramics with a low
coefficient of thermal expansion, such as Zerodur (the brand name)
of Schott AG are employed as the materials. The flatness degree of
the upper surface (the surface) of CD bar 46 is set high to be
around the same level as a so-called datum plane plate. Further, as
is shown in FIG. 2, a reference grating (e.g. a diffraction
grating) 52 having a periodic direction in the Y-axis direction is
respectively formed in the vicinity of the end portions on one side
and the other side in the longitudinal direction of CD bar 46. The
pair of reference gratings 52 are formed apart from each other at a
predetermined distance in the symmetrical placement with respect to
the center in the X-axis direction of CD bar 46, that is, a
centerline CL.
[0085] Further, on the upper surface of CD bar 46, a plurality of
reference marks M are formed as is shown in FIG. 2. The plurality
of reference marks M are formed in three-row arrays in the Y-axis
direction in the same pitch, and the array of each row is formed
being shifted from each other by a predetermined distance in the
X-axis direction. As each of reference marks M, a two-dimensional
mark having a size that can be detected by the primary alignment
system and secondary alignment systems (to be described later) is
used. Reference mark M may also be different in shape
(constitution) from fiducial mark FM described earlier, but in the
embodiment, reference mark M and fiducial mark FM have the same
constitution and also they have the same constitution with that of
the alignment mark on wafer W. Incidentally, in the embodiment, the
surface of CD bar 46 and the surface of measurement stage MST
(which may include the measurement members described above) are
also covered with a liquid repellent film (a water repellent film)
severally.
[0086] Also on the +Y end surface and the -X end surface of
measurement stage MST, reflection surfaces 19a and 19b are formed
similar to wafer stage WST as described above (refer to FIG. 2). By
projecting an interferometer beam (a measurement beam), as is shown
in FIG. 2, to reflection surfaces 19a and 19b and receiving a
reflected light of each interferometer beam, Y-axis interferometer
18 and an X-axis interferometer 130 (X-axis interferometer 130 is
not shown in FIG. 1, refer to FIG. 2) of interferometer system 118
(refer to FIG. 5) measure a displacement of each reflection surface
from a reference position, that is, positional information of
measurement stage MST (e.g. including at least positional
information in the X-axis and Y-axis directions and rotational
information in the .theta.z direction), and the measurement values
are supplied to main controller 20.
[0087] In exposure apparatus 100 of the embodiment, in actual, as
is shown in FIG. 3, on a straight line LV passing through the
center of projection unit PU and being parallel to the Y-axis,
primary alignment system AL1 having a detection center at a
position that is spaced apart at a predetermined distance on the -Y
side from the center of projection unit PU is arranged in a state
of being supported by a support member 54, although omitted in
FIGS. 1 and 2 from the viewpoint of avoiding intricacy of the
drawings. Further, on one side and the other side in the X-axis
direction with primary alignment system AL1 in between, secondary
alignment systems AL2.sub.1 and AL2.sub.2, and AL2.sub.3 and
AL2.sub.4 whose detection centers are substantially symmetrically
placed with respect to straight line LV are respectively arranged.
Each secondary alignment system AL2.sub.n (n=1 to 4) is capable of
turning around a rotation center O as the center in the page
surface, and the X-position of secondary alignment system AL2.sub.n
is adjusted by the turn. Incidentally, five alignment systems AL1
and AL2.sub.1 to AL2.sub.4 are fixed to the lower surface of the
main frame that holds projection unit PU. However, the present
invention is not limited thereto, and five alignment systems AL1
and AL2.sub.1 to AL2.sub.4 may also be arranged, for example, at
the measurement frame described above.
[0088] In the embodiment, as each of primary alignment system AL1
and four secondary alignment systems AL2.sub.1 to AL2.sub.4, for
example, an FIA (Field Image Alignment) system based on an image
processing method is used that irradiates a broadband detection
beam that does not expose the resist on a wafer to a subject mark,
and captures an image of the subject mark formed on a
light-receiving plane by the reflected light from the subject mark
and an image of an index (an index pattern on an index plate
arranged within each alignment system, not shown), using an imaging
device (such as CCD), and then outputs their imaging signals. The
imaging signal from each of primary alignment system AL1 and four
secondary alignment systems AL2.sub.1 to AL2.sub.4 is supplied to
main controller 20 in FIG. 5.
[0089] Next, encoder system 200 in exposure apparatus 100 of the
embodiment will be described referring to FIG. 3. Incidentally, in
FIG. 3, measurement stage MST is omitted and a liquid immersion
area that is formed by water Lq held in the space between
measurement stage MST and tip lens 191 is denoted by a reference
sign 14.
[0090] As is shown in FIG. 3, in exposure apparatus 100 of the
embodiment, four head units 62A to 62D of the encoder system are
placed in a state of surrounding the periphery of nozzle unit 32
described above. Although omitted in the drawings such as FIG. 3
from the viewpoint of avoiding intricacy of the drawings, in actual
head units 62A to 62D are fixed to the main frame that holds
projection unit PU described above in a suspended state via a
support member. Incidentally, for example, in the case where
projection unit PU is supported in a suspended state, head units
62A to 62D may be supported in a suspended state integrally with
projection unit PU, or may be arranged at the measurement frame
described above.
[0091] Head units 62A and 62C are placed on the +X side and the -X
side of projection unit PU respectively having the longitudinal
direction in the X-axis direction, and also symmetrically with
respect to optical axis AX of projection optical system PL at the
same distance spaced apart from optical axis AX. Further, head
units 62B and 62D are placed on the +Y side and the -Y side of
projection unit PU respectively having the longitudinal direction
in the Y-axis direction, and also at the same distance spaced apart
from optical axis AX of projection optical system PL.
[0092] As is shown in FIG. 3, each of head units 62A and 62C is
equipped with a plurality (six in this case) of Y heads 64 that are
placed at a predetermined distance on straight line LH that passes
through optical axis AX of projection optical system PL along the
X-axis direction and also is parallel with the X-axis. Head unit
62A constitutes a multiple-lens (six-lens in this case) Y linear
encoder (hereinafter, shortly referred to as a "Y encoder" or an
"encoder" as needed) 70A (refer to FIG. 5) that measures the
position in the Y-axis direction (the Y-position) of wafer stage
WST using Y scale 39Y.sub.1 described above. Similarly, head unit
62C constitutes a multiple-lens (six-lens in this case) Y linear
encoder 70C (refer to FIG. 5) that measures the Y-position of wafer
stage WST using Y scale 39Y.sub.2 described above. In this case, a
distance between adjacent Y heads 64 (i.e. the measurement beams)
that are equipped in head units 62A and 62C is set shorter than a
width of Y scales 39Y.sub.1 and 39Y.sub.2 described above in the
X-axis direction (to be more precise, the length of the grating
line). Further, out of a plurality of Y heads 64 that are equipped
in each of head units 62A and 62C, Y head 64 located innermost is
fixed to the lower end portion of barrel 40 of projection optical
system PL (to be more precise, to the side of nozzle unit 32
enclosing tip lens 191) so as to be placed as close as possible to
the optical axis of projection optical system PL.
[0093] Head units 62A and 62C are equipped with six Z sensors
76.sub.1 to 76.sub.6 and 74.sub.1 to 74.sub.6 (not shown in FIG. 3,
refer to FIG. 5) respectively, which are arranged at the same
X-positions as Y heads 64 equipped in head units 62A and 62C
respectively but whose Y-positions are apart from Y heads 64 at a
predetermined distance to the +Y side.
[0094] As is shown in FIG. 5, Z sensors 74.sub.1 to 74.sub.6 and
76.sub.1 to 76.sub.6 are connected to main controller 20 via a
processor (not shown). Z sensors 72a to 72d (their placement will
be described later) are also connected to main controller 20 via
the processor.
[0095] As each of the Z sensors, a sensor that irradiates a light
to wafer stage WST from above and receives the reflected light,
thereby measuring positional information of the upper surface of
wafer stage WST (in the embodiment, the measurement surface of the
Y scale which is subject to measurement (the surface subject to
measurement)) in the Z-axis direction orthogonal to the XY plane,
at the irradiation point of the light, that is, a displacement
sensor based on an optical method (a sensor based on an optical
pickup method) having a configuration like an optical pickup used
in a CD drive device is used as an example.
[0096] Main controller 20 selects an arbitrary Z sensor from among
Z sensors 72a to 72d, Z sensors 74.sub.1 to 74.sub.6 and Z sensors
76.sub.1 to 76.sub.6 via the processor to make the arbitrary Z
sensor be in an operating condition, and receives surface position
information detected by the Z sensor in the operating
condition.
[0097] To be more specific, each Z sensor is equipped with a focus
sensor, a sensor main section that houses the focus sensor and a
drive section that drives the sensor main section in the Z-axis
direction, and a measurement section that measures the displacement
of the sensor main section in the Z-axis direction, and the like
(none of which are shown).
[0098] As the focus sensor, a displacement sensor based on an
optical method similar to the optical pickup that optically reads
the displacement of the surface subject to measurement by
irradiating a detection beam to the surface subject to measurement
and receiving the reflected light is used. The output signal of the
focus sensor (which is also called focus error) is sent to the
drive section. According to the output signal from the focus
sensor, the drive section drives the sensor main section in the
Z-axis direction so as to keep a distance between the sensor main
section and the surface subject to measurement constant (to be more
precise, so as to keep the surface subject to measurement at the
best focus position of an optical system of the focus sensor). With
this operation, the sensor main section follows the displacement of
the surface subject to measurement in the Z-axis direction and the
focus-lock state is maintained.
[0099] As the measurement section, in the embodiment, an encoder
based on a diffraction interference method is used as an example.
The measurement section reads the displacement of the sensor main
section in the Z-axis direction.
[0100] In the embodiment, as is described above, in the focus-lock
state, the sensor main section is displaced in the Z-axis direction
so that a distance between the sensor main section and the surface
subject to measurement is kept constant. Accordingly, by the
encoder head of the measurement section measuring the displacement
of the sensor main section in the Z-axis direction, the surface
position (the Z-position) of the surface subject to measurement is
measured. The measurement values of the encoder head of the
measurement section are supplied to main controller 20 via the
processor described above as the measurement values of the Z
sensor.
[0101] As is shown in FIG. 3, head unit 62B is equipped with a
plurality (seven in this case) of X heads 66 that are placed on
straight line LV at a predetermined distance along the Y-axis
direction. Further, head unit 62D is equipped with a plurality
(eleven in this case, out of eleven X heads, however, three X heads
that overlap primary alignment system AL1 are not shown in FIG. 3)
of X heads 66 that are placed on straight line LV at a
predetermined distance. Head unit 62B constitutes a multiple-lens
(seven-lens, in this case) X linear encoder (hereinafter, shortly
referred to as an "X encoder" or an "encoder" as needed) 70B (refer
to FIG. 5) that measures the position in the X-axis direction (the
X-position) of wafer stage WST using X scale 39X.sub.1 described
above. Further, head unit 62D constitutes a multiple-lens
(eleven-lens, in this case) X linear encoder 70D (refer to FIG. 5)
that measures the X-position of wafer stage WST using x scale
39X.sub.2 described above. Further, in the embodiment, for example,
when alignment (to be described later) or the like is performed,
two X heads 66 out of eleven X heads 66 that are equipped in head
unit 62D simultaneously face X scale 39X.sub.1 and X scale
39X.sub.2 respectively in some cases. In these cases, either of X
scale 39X.sub.1 and X head 66 facing x scale 39X.sub.1, or X scale
39X.sub.2 and X head 66 facing X scale 39X.sub.2 may be used. In
either case, X linear encoder 70D is constituted by the X head 66
of head unit 62D facing the X scale.
[0102] Herein, some of eleven X heads 66, in this case, three X
heads are attached below support member 54 that supports primary
alignment system AL1. Further, a distance between adjacent X heads
66 (i.e. measurement beams) that are equipped in each of head units
62B and 62D is set shorter than a width in the Y-axis direction of
X scales 39X.sub.1 and 39X.sub.2 described above (to be more
precise, the length of the grating line). Further, X head 66
located innermost out of a plurality of X heads 66 that are
equipped in each of head units 62B and 62D is fixed to the lower
end portion of the barrel of projection optical system PL (to be
more precise, to the side of nozzle unit 32 enclosing tip lens 191)
so as to be placed as close as possible to the optical axis of
projection optical system PL.
[0103] moreover, on the -X side of secondary alignment system
AL2.sub.1 and on the +X side of secondary alignment system
AL2.sub.4, Y heads 64y.sub.1 and 64y.sub.2 are respectively
arranged, whose detection points are placed on a straight line
parallel to the X-axis that passes through the detection center of
primary alignment system AL1 and are substantially symmetrically
placed with respect to the detection center. The distance between Y
heads 64y.sub.1 and 64y.sub.2 is set substantially equal to the
distance between a pair of reference gratings 52 on CD bar 46
described previously. Y heads 64y.sub.1 and 64y.sub.2 face Y scales
39Y.sub.2 and 39Y.sub.1 respectively in the state shown in FIG. 3
where the center of wafer W on wafer stage WST is on straight line
LV. On the alignment operation (to be described later) or the like,
Y scales 39Y.sub.2 and 39Y.sub.1 are placed facing Y heads
64y.sub.1 and 64y.sub.2 respectively, and the Y-position (and the
.theta.z rotation) of wafer stage WST is measured by Y heads
64y.sub.1 and 64y.sub.2 (i.e. Y encoders 70E and 70F (refer to FIG.
5) constituted by Y heads 64y.sub.1 and 64y.sub.2).
[0104] Further, in the embodiment, when baseline measurement of the
secondary alignment systems (to be described later) or the like is
performed, Y heads 64y.sub.1 and 64y.sub.2 face a pair of reference
gratings 52 of CD bar 46 respectively, and the Y-position of CD bar
46 is measured at the position of each of reference gratings 52 by
Y heads 64y.sub.1 and 64y.sub.2 facing the pair of reference
gratings 52. In the following description, encoders that are
constituted by Y heads 64y.sub.1 and 64y.sub.2 facing reference
gratings 52 respectively are referred to as Y-axis linear encoders
70E.sub.2 and 70F.sub.2. Further, in order to distinguish, the Y
encoders that are constituted by Y heads 64y.sub.1 and 64y.sub.2
that face Y scales 39y.sub.2 and 39y.sub.1 are referred to as Y
encoders 70E.sub.1 and 70F.sub.1.
[0105] The measurement values of linear encoders 70A to 70F
described above are supplied to main controller 20, and main
controller 20 controls the position of wafer stage WST within the
XY plane based on the measurement values of linear encoders 70A to
70D, and also controls the rotation of CD bar 46 in the .theta.z
direction based on the measurement values of linear encoders 70E
and 70F.
[0106] Further, as is shown in FIG. 3, at exposure apparatus 100
(stage device 50) of the embodiment, six detection devices
PDX.sub.1 to PDX.sub.4, PDY.sub.1 and PDY.sub.2 (the hatching are
drawn in FIG. 3) are arranged that are used to detect the surface
state (e.g. the existence state of foreign substance or the like)
of scales 39X.sub.1, 39X.sub.2, 39Y.sub.1 and 39Y.sub.2, and a pair
of reference gratings 52 on CD bar 46. Detection devices PDX.sub.1
to PDX.sub.4, PDY.sub.1 and PDY.sub.2 may be supported in a
suspended state by the main frame (including the barrel platform
described above) that holds projection unit PU, or may be fixed to
another frame member that is separate from the main frame.
[0107] Out of the six detection devices, detection device PDX.sub.1
is arranged at a position that is on the +Y side and on the -X side
of projection unit PU, and detection device PDX.sub.2 is arranged
at a position that is on the +Y side and on the +X side of
projection unit PU and is bilaterally-symmetric with detection
device PDX.sub.1 with reference to straight line LV. Moreover,
detection device PDX.sub.3 is arranged at a position that is on the
-Y side and on the -X side of projection unit PU, and detection
device PDX.sub.4 is arranged at a position that is
bilaterally-symmetric with detection device PDX.sub.3 with
reference to straight line LV. Further, detection device PDY.sub.1
is placed at a position that is on the -Y side of head unit 62C and
on the +Y side of an irradiation system 90a (to be described
later), and detection device PDY.sub.2 is placed at a position that
is on the -Y side of head unit 62A and on the +Y side of a
photodetection system 90b (to be described later) and is
bilaterally-symmetric with detection device PDY.sub.1 with
reference to straight line LV.
[0108] Detection device PDY.sub.1 includes an irradiation system
69A that irradiates a detection beam to the surface of scale
39Y.sub.2 and a photodetection system 69B that receives the
detection beam scattered at the surface of scale 39Y.sub.2, as is
shown in FIG. 4A.
[0109] Irradiation system 69A includes a light-transmitting section
61 including, for example, a laser light source, a collimator lens,
an irradiation light adjusting member, an anamorphic prism, a
diaphragm and the like, and a mirror 63. The laser light source is
a semiconductor laser that emits a detection beam having a
wavelength of, for example, around 780 nm.
[0110] The detection beam emitted from light-transmitting section
61 is reflected off mirror 63 and is incident on the surface of
scale 39Y.sub.2 at an incident angle close to 90 degrees (89
degrees in FIG. 4). That is, the detection beam is incident
substantially parallel to the surface of scale 39Y.sub.2, and
therefore, as is shown in FIG. 4B, the detection beam is irradiated
to a band-shaped irradiation area BA that extends on the
substantially entire area in the X-axis direction of the surface of
scale 39Y.sub.2. Then, in the case where a foreign substance (a
particle) 11 exists on the surface of scale 39Y.sub.2 as is shown
in FIG. 4A, the detection beam irradiated to foreign substance 11
is scattered.
[0111] Photodetection system 69B includes a photodetection lens 65
and an image sensor 67 as is shown in FIG. 4A. As image sensor 67,
for example, a photoelectric detector such as a one-dimensional CCD
(Charge-Coupled Device) or the like is used.
[0112] In photodetection system 69B, image sensor 67 receives the
scattered light that is incident on photodetection lens 65 out of
the scattered lights that have been scattered at foreign substance
11 on the surface of scale 39Y.sub.2. In this case, the
photodetection position of the scattered light on image sensor 67
changes according to the X-position of foreign substance 11. The
photodetection result of image sensor 67 is sent to main controller
20 (refer to FIG. 5). Main controller 20 identifies the position of
foreign substance 11 based on the photodetection result.
[0113] Incidentally, detection device PDY.sub.2 also has a
configuration similar to detection device PDY.sub.1 described
above. Further, detection devices PDX.sub.1 to PDX.sub.4 have
configurations similar to detection devices PDY.sub.1 and PDY.sub.2
although the irradiation directions of the detection beams of
detection devices PDX.sub.1 to PDX.sub.4 are different from those
of detection devices PDY.sub.1 and PDY.sub.2. Accordingly, the
position of foreign substance 11 that exists on the scale
(39X.sub.1 or 39X.sub.2) can be detected by using detection devices
PDX.sub.1 to PDX.sub.4. In the embodiment, positional information
of wafer stage WST measured by the encoder system described above
is used when performing the foreign substance detection, but
positional information of wafer stage WST measured by
interferometer system 118 may be used instead or in
combination.
[0114] Incidentally, in the embodiment, because the detection beam
from the detection device is irradiated to scales 39X.sub.1,
39X.sub.2, 39Y.sub.1 and 39Y.sub.2 and reference gratings 52 of CD
bar 46, there is the possibility that the diffracted light at the
diffraction gratings of scales 39X.sub.1, 39X.sub.2, 39Y.sub.1 and
39Y.sub.2 and reference gratings 52 of CD bar 46 is received by
photodetection system 69B. In the embodiment, however, the grating
pitch and the orientation of the diffraction gratings are constant
and photodetection system 69B receives the diffracted lights in the
same state at all times, and therefore, the detection of the
scattered light from foreign substance 11 is hardly affected by the
photodetection of the diffracted light. This is because the light
quantity (the light intensity) of the received light is increased
by the light quantity of the diffracted light from the diffraction
gratings, but this increased quantity (the noise component) does
not depend on the position while the scattered light from foreign
substance 11 differs depending on the position. However, from the
viewpoint of improving the S/N ratio of the detection signal of
foreign substance, it is preferable to design the placement or the
like of photodetection system 69B so that image sensor 67 does not
receive the diffracted light.
[0115] Moreover, in exposure apparatus 100 of the embodiment, as is
shown in FIG. 3, a multipoint focal position detection system
(hereinafter, shortly referred to as a "multipoint AF system")
based on an oblique incident method is arranged, which is composed
of irradiation system 90a and photodetection system 90b, and has a
configuration similar to the one disclosed in, for example, Kokai
(Japanese Unexamined Patent Application Publication) No. 06-283403
(the corresponding U.S. Pat. No. 5,448,332) and the like. In the
embodiment, as an example, irradiation system 90a is placed on the
Y side of the -X end portion of head unit 62C described above and
photodetection system 90b is placed on the -Y side of the +X end
portion of head unit 62A described above in a state of facing
irradiation system 90a.
[0116] A plurality of detection points of the multipoint AF system
(90a, 90b) are placed at a predetermined distance along the X-axis
direction on the surface to be detected. In the embodiment, the
plurality of detection points are placed, for example, in the
matrix arrangement having one row and M columns (M is a total
number of detection points) or having two rows and N columns (N is
a half of a total number of detection points). In FIG. 3, the
plurality of detection points to which a detection beam is
severally irradiated are not individually shown, but are shown as
an elongate detection area AF that extends in the X-axis direction
between irradiation system 90a and photodetection system 90b. Since
the length of detection area AF in the X-axis direction is set to
around the same as the diameter of wafer W, positional information
(surface position information) in the Z-axis direction of the
substantially entire surface of wafer W can be measured by only
scanning wafer W in the Y-axis direction once. Further, since
detection area AF is placed between liquid immersion area 14
(exposure area IA) described previously and the detection areas of
the alignment systems (AL1, AL2.sub.1, AL2.sub.2, AL2.sub.3 and
AL2.sub.4) in the Y-axis direction, the detection operations of the
multipoint AF system and the alignment systems can be performed in
parallel. The multipoint AF system may also be arranged at the main
frame that holds projection unit PU or the like, but is to be
arranged at the measurement frame described earlier in the
embodiment.
[0117] Incidentally, the plurality of detection points are to be
placed in one row and M columns, or two rows and N columns, but the
number(s) of rows and/or columns is/are not limited to these
numbers. However, in the case where the number of rows is two or
more, the positions in the X-axis direction of detection points are
preferably made to be different even between the different rows.
Moreover, the plurality of detection points are to be placed along
the X-axis direction. However, the present invention is not limited
to this, and all of or some of the plurality of detection points
may also be placed at different positions in the Y-axis direction.
For example, the plurality of detection points may also be placed
along a direction that intersects both of the X-axis and the
Y-axis. That is, the positions of the plurality of detection points
only have to be different at least in the X-axis direction.
Further, a detection beam is to be irradiated to the plurality of
detection points in the embodiment, but a detection beam may also
be irradiated to, for example, the entire area of detection area
AF. Furthermore, the length of detection area AF in the X-axis
direction does not have to be nearly the same as the diameter of
wafer W.
[0118] Incidentally, although omitted in FIG. 3, in the vicinity of
detection points located at both ends out of a plurality of
detection points of the multipoint AF system, that is, in the
vicinity of both end portions of detection area AF, a pair of Z
sensors 72a and 72b and a pair of 72c and 72d described above
(refer to FIG. 5) are arranged in the symmetrical placement with
respect to straight line LV described above. As the surface
position sensors, a sensor that irradiates a light to wafer stage
WST from above, receives the reflected light and measures
positional information of the wafer stage WST surface in the Z-axis
direction orthogonal to the XY plane at an irradiation point of the
light, as an example, an optical displacement sensor (a sensor
based on an optical pickup method), which has a configuration like
an optical pickup used in a CD drive device, is used.
[0119] In FIG. 3, a reference sign UP denotes an unloading position
where a wafer on wafer stage WST is unloaded, and a reference sign
LP denotes a loading position where a wafer is loaded on wafer
stage WST. In the embodiment, unloading position UP and loading
position LP are set symmetrically with respect to straight line LV.
Incidentally, although unloading position UP and loading position
LP are separately set as the exchange position of wafer W,
unloading position UP and loading position LP may be the same
position.
[0120] FIG. 5 shows a main configuration of the control system of
exposure apparatus 100. The control system is mainly configured of
main controller 20 composed of a microcomputer (or a workstation)
that performs overall control of the entire apparatus.
Incidentally, in FIG. 5, various sensors such as uneven illuminance
measuring sensor 94, aerial image measuring instrument 96 and
wavefront aberration measuring instrument 98 that are arranged at
measurement stage MST are collectively shown as a group of sensors
99.
[0121] In exposure apparatus 100 of the embodiment having the
configuration described above, since the placement of the X scales
and Y scales on wafer stage WST as described above and the
placement of the X heads and Y heads as described above are
employed, X scale 39X.sub.1 and 39X.sub.2 respectively face head
units 62B and 62D (X heads 66) and also Y scales 39Y.sub.1 and
39Y.sub.2 respectively face head units 62A and 62C (Y heads 64) or
Y heads 64Y.sub.1 and 64Y.sub.2 without fail in an effective stroke
range of wafer stage WST (i.e. a range in which wafer stage WST
moves for the alignment and the exposure operation, in the
embodiment), as is exemplified in the drawings such as FIGS. 6A and
6B. Incidentally, in FIGS. 6A and 6B, the heads that face the
corresponding X scales or Y scales are indicated by being
circled.
[0122] Therefore, in the effective stroke range of wafer stage WST
described above, main controller 20 can control positional
information (including rotational information in the .theta.z
direction) of wafer stage WST within the XY plane with high
precision by controlling each motor constituting stage drive system
124, based on measurement values of at least three encoders of
encoders 70A to 70D, or at least three encoders of encoders
70E.sub.1, 70F.sub.1, 70B and 70D. Since the influence of air
fluctuations that the measurement values of encoders 70A to 70F
receive is small enough to be ignored when comparing with the
interferometer, the short-term stability of the measurement values
that is affected by air fluctuations is remarkably better than that
of the interferometer. Incidentally, in the embodiment, the size
(e.g. the number of the heads and/or the distance between the
heads) of head units 62B, 62D, 62A and 62C is set in accordance
with the effective stroke range of wafer stage WST and the size of
the scales (i.e. the formation range of the diffraction gratings)
or the like. Accordingly, in the effective stroke range of wafer
stage WST, all of four scales 39X.sub.1, 39X.sub.2, 39Y.sub.1 and
39Y.sub.2 face head units 62B, 62D, 62A and 62C respectively, but
all the four scales do not have to face the corresponding head
units. For example, one of X scales 39X.sub.1 and 39X.sub.2 and/or
one of Y scales 39Y.sub.1 and 39Y.sub.2 do not have to face the
head unit. In the case where one of X scales 39X.sub.1 and
39X.sub.2 or one of Y scales 39Y.sub.1 and 39Y.sub.2 does not face
the head unit, three scales face the head units in the effective
stroke range of wafer stage WST, and therefore positional
information of wafer stage WST in the X-axis direction, the Y-axis
direction and the .theta.z direction can be constantly measured.
Further, in the case where one of X scales 39X.sub.1 and 39X.sub.2
and one of Y scales 39Y.sub.1 and 39Y.sub.2 do not face the head
units, two scales face the head units in the effective stroke range
of wafer stage WST, and therefore positional information of wafer
stage WST in the .theta.z direction cannot be constantly measured,
but positional information of wafer stage WST in the X-axis
direction and the Y-axis direction can be constantly measured. In
this case, position control of wafer stage WST may also be
performed by using positional information of wafer stage WST in the
.theta.z direction measured by interferometer system 118 in
combination.
[0123] Further, when wafer stage WST is driven in the X-axis
direction as indicated by an outline arrow in FIG. 6A, Y head 64
that measures the position in the Y-axis direction of wafer stage
WST is sequentially switched to adjacent Y head 64 as indicated by
arrows e.sub.1 and e.sub.2 in the drawing. For example, Y head 64
circled by a solid line is switched to Y head 64 circled by a
dotted line. Therefore, the measurement values are carried over
before and after the switching. That is, in the embodiment, in
order to perform the switching of Y heads 64 and the carryover of
the measurement values smoothly, a distance between adjacent Y
heads 64 that are equipped in head units 62A and 62C is set shorter
than a width of Y scales 39Y.sub.1 and 39Y.sub.2 in the x-axis
direction, as is described previously.
[0124] Further, although omitted in the drawing, the switching (the
linkage process) between adjacent Z sensors 76 and between adjacent
Z sensors 74, which are equipped in head units 62A and 62C
respectively, is performed in the similar manner to the case of the
Y heads described above.
[0125] Further, in the embodiment, since a distance between
adjacent X heads 66 that are equipped in head units 62B and 62D is
set shorter than a width of X scales 39X.sub.1 and 39X.sub.2 in the
Y-axis direction as is described previously, when wafer stage WST
is driven in the Y-axis direction as indicated by an outline arrow
in FIG. 6B, similarly to the case described above, X head 66 that
measures the position in the X-axis direction of wafer stage WST is
sequentially switched to adjacent X head 66 (e.g. X head 66 circled
by a solid line is switched to X head 66 circled by a dotted line),
and the measurement values are carried over before and after the
switching.
[0126] Next, configurations and the like of encoders 70A to 70F
will be described, focusing on Y encoder 70A that is enlargedly
shown in FIG. 7A, as a representative. FIG. 7A shows one Y head 64
of head unit 62A that irradiates a detection light (a measurement
beam) to Y scale 39Y.sub.1.
[0127] Y head 64 is mainly configured of three sections, which are
an irradiation system 64a, an optical system 64b and a
photodetection system 64c.
[0128] Irradiation system 64a includes a light source that emits a
laser beam LB in a direction inclined at an angel of 45 degrees
with respect to the Y-axis and Z-axis, for example, a semiconductor
laser LD, and a lens L1 that is placed in the optical path of laser
beam LB emitted from semiconductor laser LD.
[0129] Optical system 64b is equipped with a polarization beam
splitter PBS whose separation plane is parallel to an XZ plane, a
pair of reflection mirrors R1a and R1b, lenses L2a and L2b, quarter
wavelength plates (hereinafter, referred to as .lamda./4 plates)
WP1a and WP1b, reflection mirrors R2a and R2b, and the like.
[0130] Photodetection system 64c includes a polarizer (an
analyzer), a photodetector, and the like.
[0131] In Y encoder 70A, laser beam LB emitted from semiconductor
laser LD is incident on polarization beam splitter PBS via lens L1,
and is split by polarization into two beams LB.sub.1 and LB.sub.2.
Beam LB.sub.1 having been transmitted through polarization beam
splitter PBS reaches reflective diffraction grating RG that is
formed on Y scale 39Y.sub.1, via reflection mirror R1a, and beam
LB.sub.2 reflected off polarization beam splitter PBS reaches
reflective diffraction grating RG via reflection mirror R1b.
Incidentally, "split by polarization" in this case means the
splitting of an incident beam into a P-polarization component and
an S-polarization component.
[0132] Predetermined-order diffracted beams that are generated from
diffraction grating RG due to irradiation of beams LB.sub.1 and
LB.sub.2, for example, the first-order diffracted beams are
severally converted into a circular polarized light by .lamda./4
plates WP1b and WP1a via lenses L2b and L2a, and reflected by
reflection mirrors R2b and R2a and then the beams pass through
.lamda./4 plates WP1b and WP1a again and reach polarization beam
splitter PBS by tracing the same optical path in the reversed
direction.
[0133] Each of the polarization directions of the two beams that
have reached polarization beam splitter PBS is rotated at an angle
of 90 degrees with respect to the original direction.
[0134] Therefore, the first-order diffracted beam of beam LB.sub.1
that was previously transmitted through polarization beam splitter
PBS is reflected off polarization beam splitter PBS and is incident
on photodetection system 64c, and also the first-order diffracted
beam of beam LB.sub.2 that was previously reflected off
polarization beam splitter PBS is transmitted through polarization
beam splitter PBS and is synthesized concentrically with the
first-order diffracted beam of beam LB.sub.1 and is incident on
photodetection system 64c.
[0135] Then, the polarization directions of the two first-order
diffracted beams described above are uniformly arranged by the
analyzer inside photodetection system 64c and the beams interfere
with each other to be an interference light, and the interference
light is detected by the photodetector and is converted into an
electric signal in accordance with the intensity of the
interference light.
[0136] As is obvious from the above description, in Y encoder 70A,
since the optical path lengths of two beams to be interfered are
extremely short and also are almost equal to each other, the
influence by air fluctuations can mostly be ignored. Then, when Y
scale 39Y.sub.1 (i.e. wafer stage WST) moves in the measurement
direction (the Y-axis direction, in this case), the phase of each
of the two beams changes and thus the intensity of the interference
light changes. This change in the intensity of the interference
light is detected by photodetection system 64c, and positional
information in accordance with the intensity change is output as
the measurement value of Y encoder 70A. Other encoders 70B, 70C,
70D and the like are also configured similar to encoder 70A. As
each of the encoders, for example, an encoder having a resolution
around 0.1 nm is used. Incidentally, as is shown in FIG. 7B, in the
encoders of the embodiment, laser beam LB having a sectional shape
that is elongated in the periodic direction of diffraction grating
RG composed of the grating lines may also be used as a detection
light. In FIG. 7B, beam LB is shown exaggeratingly larger, compared
to the grating lines of diffraction grating RG.
[0137] Next, a parallel processing operation using wafer stage WST
and measurement stage MST in exposure apparatus 100 of the
embodiment will be described, referring to FIGS. 8 to 21.
Incidentally, during the operation described below, main controller
20 performs opening/closing control of each valve of liquid supply
device 5 and liquid recovery device 6 of local liquid immersion
device 8 as is described earlier, and the space on the outgoing
surface side of tip lens 191 of projection optical system PL is
constantly filled with water. However, description regarding
control of liquid supply device 5 and liquid recovery device 6 will
be omitted in the following description, in order to make the
description easily understandable. Further, the following
description regarding the operation will be made using many
drawings, but the reference signs of the same members are shown in
some drawings and not shown in the other drawings. That is, the
reference signs shown are different in each of the drawings, but
these drawings show the same configuration regardless of existence
or non-existence of the reference signs. The same is true also in
each of the drawings used in the description above.
[0138] Incidentally, as a premise, baseline measurement (baseline
check) of primary alignment system AL1 and baseline measurement
operations of secondary alignment system AL2.sub.n (n=1 to 4) are
assumed to have been already performed. Herein, the baseline of
primary alignment system AL1 means the positional relation (or the
distance) between the projection position of a pattern (e.g. a
pattern of reticle R) by projection optical system PL and the
detection center of primary alignment system AL1, and the baseline
of secondary alignment system AL2.sub.n means the relative position
of (the detection center of) each secondary alignment system
AL2.sub.n with reference to (the detection center of) primary
alignment system AL1. For example, fiducial mark FM is measured in
a state where the position of fiducial mark FM is set within the
filed (the detection area) of primary alignment system AL1, and
also aerial images of a pair of measurement marks are measured
respectively in a state where the position of fiducial mark FM is
set within exposure area IA (liquid immersion area 14) of
projection optical system PL, in an aerial image measurement
operation based on a slit-scan method using a pair of aerial image
measurement slit patterns SL similarly to the method disclosed in,
for example, Kokai (Japanese Unexamined Patent Application
Publication) No. 2002-014005 (the corresponding U.S. Patent
Application Publication No. 2002/0041377) and the like, and based
on the respective detection results and measurement results, the
baseline of primary alignment system AL1 is computed. Further, for
example, a specific alignment mark on wafer W (a process wafer) at
the head of a lot is detected beforehand by each of primary
alignment system AL1 and secondary alignment systems AL2.sub.1 to
AL2.sub.4, and the baseline of secondary alignment system AL2.sub.n
is computed from the detection results and the measurement values
of encoders 70A to 70D at the time of the detection. Incidentally,
main controller 20 adjusts the position in the X-axis direction of
secondary alignment systems AL2.sub.1 to AL2.sub.4 beforehand in
conformity with the placement of alignment shot areas.
[0139] FIG. 8 shows a state where exposure based on a step-and-scan
method is being performed to wafer W (in this case, to be a mid
wafer of a certain lot (one lot containing 25 or 50 wafers), as an
example) on wafer stage WST. During the exposure, main controller
20 controls the position within the XY plane (including the
.theta.z rotation) of wafer stage WST, based on the measurement
values of at least three encoders out of two X heads 66 (X encoders
70B and 70D) indicated by being circled in FIG. 8 that face X
scales 39X.sub.1 and 39X.sub.2 respectively and two Y heads 64 (Y
encoders 70A and 70C) indicated by being circled in FIG. 8 that
face Y scales 39Y.sub.1 and 39Y.sub.2 respectively. Further, main
controller 20 controls the position in the Z-axis direction, and
the .theta.y rotation (rolling) and the .theta.x rotation
(pitching) of wafer stage WST, based on the measurement values of Z
sensors 74.sub.i and 76.sub.j ("i" and "j" are either of 1 to 6)
described above arranged inside head units 62A and 62C, and
controls the .theta.x rotation (pitching) based on the measurement
values of Y-axis interferometer 16.
[0140] Incidentally, the Z sensors are placed also in the Y-axis
direction inside or in the vicinity of head units 62A and 62C, and
the position in the Z-axis direction, the .theta.y rotation
(rolling) and the .theta.x rotation (pitching) of wafer stage WST
may be controlled based on the measurement values of a plurality of
the Z sensors. In either case, the control of the position in the
Z-axis direction, the .theta.y rotation and the .theta.x rotation
of wafer stage WST (focus leveling control of wafer W) during the
exposure is performed based on the results of the focus mapping (to
be described later) that was performed beforehand.
[0141] The foregoing exposure operation is performed by main
controller 20 repeating an inter-shot moving operation in which
wafer stage WST is moved to a scanning starting position
(accelerating starting position) for exposure of each shot area on
wafer W based on the result of wafer alignment performed
beforehand, for example, Enhanced Global Alignment (EGA, which will
be described later), the latest baselines of alignment systems AL1
and AL2.sub.1 to AL2.sub.4, and the like, and a scanning exposure
operation in which a pattern formed on reticle R is transferred to
each shot area by a scanning exposure method. Incidentally, the
exposure operation described above is performed in a state where
water is held in the space between tip lens 191 and wafer W.
Further, the exposure operation is performed in the order from the
shot area located on the -Y side to the shot area located on the +Y
side in FIG. 8. Moreover, as is disclosed in, for example, Kokai
(Japanese Unexamined Patent Application Publication) No. 61-044429
(the corresponding U.S. Pat. No. 4,780,617), in the EGA method,
some (e.g. around 8 to 16) of a plurality of shot areas on wafer W
are selected as alignment shot areas, and alignment marks on the
selected shot areas are detected by alignment system AL.sub.1 and
AL2.sub.4 to AL2.sub.4. Then, by performing statistical computation
of positional information of the alignment marks that has been
detected, positional information (alignment coordinate) of each
shot areas on wafer W is computed. In this EGA method, not only the
positional information of shot areas but also information on the
scaling and the rotation of wafer W or the like can be
obtained.
[0142] Then, as is shown in FIG. 9, before exposure to wafer W ends
(the last shot area is exposed), main controller 20 moves
measurement stage MST to the position shown in FIG. 10 by
controlling stage drive system 124 based on the measurement value
of Y-axis interferometer 18 while maintaining the measurement value
of X-axis interferometer 130 to a constant value. On this
operation, the end surface on the -Y side of CD bar 46 and the end
surface on the +Y side of wafer stage WST are in contact with each
other. Incidentally, the noncontact state (the proximity state) may
also be kept by, for example, monitoring the measurement values of
the interferometer or the encoder that measures the position of
each stage in the Y-axis direction and separating measurement stage
MST and wafer stage WST in the Y-axis direction at a distance of
around 300 .mu.m.
[0143] Subsequently, as is shown in FIG. 11, while keeping the
positional relation in the Y-axis direction between wafer stage WST
and measurement stage MST, main controller 20 starts an operation
of driving measurement stage MST to the -Y direction and also
starts an operation of driving wafer stage WST toward unloading
position UP. When these operations are started, in the embodiment,
measurement stage MST is moved only to the -Y direction, and wafer
stage WST is moved to the -Y direction and -X direction.
[0144] When main controller 20 drives wafer stage WST and
measurement stage MST simultaneously as is described above, water
that is held in the space between tip lens 191 of projection unit
PU and wafer W (water in liquid immersion area 14) sequentially
moves from wafer W to plate 28, CD bar 46, and measurement stage
MST, according to movement of wafer stage WST and measurement stage
MST to the -Y side. Incidentally, during the foregoing movement,
the contact state (or proximity state) of wafer stage WST and
measurement stage MST is maintained. Incidentally, FIG. 11 shows a
state right before water in liquid immersion area 14 is delivered
from plate 28 to CD bar 46.
[0145] When wafer stage WST and measurement stage MST are
simultaneously and slightly driven further to the -Y direction from
the state of FIG. 11, position measurement of wafer stage WST by Y
encoders 70A and 70C cannot be performed. Therefore, right before
that, main controller 20 switches the control of the Y-position and
the .theta.z rotation of wafer stage WST from the control based on
the measurement values of Y encoders 70A and 70C to the control
based on the measurement values of Y-axis interferometer 16. Then,
after a predetermined period of time, as is shown in FIG. 12, since
CD bar 46 of measurement stage MST is positioned right below
alignment systems AL1 and AL2.sub.3, to AL2.sub.4, main controller
20 stops measurement stage MST at this position, and also drives
further wafer stage WST toward unloading position UP while
measuring the X-position of wafer stage WST by X head 66 indicated
by being circled in FIG. 12 that faces X scale 39X.sub.1 (X-linear
encoder 70B) and measuring the Y-position, the .theta.z rotation
and the like by Y-axis interferometer 16, and stops wafer stage WST
at unloading position UP. Incidentally, in the state of FIG. 12,
water is held in the space between measurement stage MST and tip
lens 191.
[0146] Subsequently, as is shown in FIGS. 12 and 13, main
controller 20 measures the relative positional relation (the
baseline) of (the detection center of) secondary alignment system
AL2n with reference to (the detection center of) primary alignment
system AL1, using reference marks M of CD bar 46. The baseline
measurement in this case is performed at intervals of each wafer
exchange, and thus hereinafter the baseline measurement is also
described as "Sec-BCHK (interval)"
[0147] In this Sec-BCHK (interval), main controller 20 adjusts the
.theta.z rotation of CD bar 46 based on the measurement values of Y
heads 64y.sub.1 and 64y.sub.2 that face a pair of reference
gratings 52 on CD bar 46 respectively (Y-axis linear encoders
70E.sub.2 and 70F.sub.2), and also adjusts the XY-position of CD
bar 46 using, for example, the measurement value of the
interferometer, based on the measurement value of primary alignment
system AL1 that detects reference mark M that is located on
centerline CL of measurement stage MST or in the vicinity
thereof.
[0148] Then, in this state, main controller 20 obtains each of the
baselines of four secondary alignment systems AL2.sub.1 to
AL2.sub.4 by simultaneously measuring reference marks M on CD bar
46 within the fields of the respective secondary alignment systems
using four secondary alignment systems AL2.sub.1 to AL2.sub.4. And,
when performing the subsequent process, drift of the baselines of
four secondary alignment systems AL2.sub.1 to AL2.sub.4 are
corrected by using the newly measured baselines.
[0149] Further, in parallel with the Sec-BCHK (interval), main
controller 20 gives the command and makes a drive system of an
unload arm (not shown) unload wafer W on wafer stage WST that stops
at unloading position UP, and also drives wafer stage WST to the +X
direction to move it to loading position LP.
[0150] Next, as is shown in FIG. 14, main controller 20 moves
measurement stage MST to an optimal waiting position (hereinafter,
referred to as an "optimal scrum waiting position") used to shift a
state of measurement stage MST from a state of being away from
wafer stage WST to the contact state (or proximity state) with
wafer stage WST described previously. In parallel with this
operation, main controller 20 gives the command and makes a drive
system of a load arm (not shown) load new wafer W onto wafer stage
WST. Incidentally, FIG. 14 shows a state where wafer W is loaded on
wafer stage WST.
[0151] In the embodiment, the above-described optimal scrum waiting
position of measurement stage MST is appropriately set in
accordance with the Y-coordinates of the alignment marks arranged
in the alignment shot areas on the wafer. With this setting, an
operation of moving measurement stage MST to the optimal scrum
waiting position that is needed on the sift to the contact state
(or proximity state) described above becomes unnecessary, and
therefore the number of movement of measurement stage MST can be
reduced by one, compared with the case where measurement stage MST
is made to wait at a position away from the optimal scrum waiting
position. Further, in the embodiment, the optimal scrum waiting
position is determined so that the shift to the contact state (or
proximity state) described above can be performed at a position
where wafer stage WST stops for the wafer alignment described
earlier.
[0152] Next, main controller 20 moves wafer stage WST to the
position shown in FIG. 15. In the middle of the movement, main
controller 20 switches control of the position of wafer stage WST
within the XY plane from the control based on the measurement value
of encoder 70B regarding the X-axis direction and the measurement
value of Y-axis interferometer 16 regarding the Y-axis direction
and the .theta.z rotation, to the control based on the measurement
values of three encoders, which are either of two X heads 66
indicated by being circled in FIG. 15 that face X scales 39X.sub.1
and 39X.sub.2 (encoder 70D) and two Y heads 64y.sub.2 and 64y.sub.1
indicated by being circled in FIG. 15 that face Y scales 39Y.sub.1
and 39Y.sub.2 (encoders 70F.sub.1 and 70E.sub.1).
[0153] Next, main controller 20 starts movement of wafer stage WST
to the +Y direction, while controlling the position of wafer stage
WST based on the measurement values of the three encoders described
above. Then, when wafer stage WST reaches the position shown in
FIG. 16, main controller 20 makes wafer stage WST and measurement
stage MST come into contact with each other (or be close to each
other at a distance of around 300 .mu.m), and immediately stops
wafer stage WST.
[0154] After the stop of wafer stage WST, main controller 20 almost
simultaneously and individually detects the alignment marks (refer
to star-shaped marks in FIG. 16) arranged in three shot areas
(hereinafter, referred to as "first alignment shot areas") using
primary alignment system AL1 and secondary alignment systems
AL2.sub.2 and AL2.sub.3, and links the detection results of three
alignment systems AL1, AL2.sub.2 and AL2.sub.3 and the measurement
values of the three encoders described above at the time of the
detection and stores them in a memory (not shown). Incidentally,
the simultaneous detection of the alignment marks arranged in the
three first alignment shot areas in this case is performed while
changing the relative positional relation in the Z-axis direction
(the focus direction) between a plurality of alignment systems AL1
and AL2.sub.1 to AL2.sub.4 and wafer W mounted on wafer stage WST
by changing the Z-position of wafer stage WST.
[0155] As is described above, in the embodiment, the shift to the
contact state (or proximity state) of measurement stage MST and
wafer stage WST is completed at the position where detection of the
alignment marks in the first alignment shot areas is performed, and
from the position, the movement to the +Y direction of both stages
WST and MST in the contact state (or proximity state) is started by
main controller 20. Prior to the start of the movement to the +Y
direction of both stages WST and MST, as is shown in FIG. 16, main
controller 20 starts irradiation of detection beams from the
multipoint AF system (90a, 90b) to wafer stage WST. With this
operation, the detection area of the multipoint AF system is formed
on wafer stage WST.
[0156] On this operation, liquid immersion area 14 is formed near
the boundary between CD bar 46 and wafer stage WST. That is, water
in liquid immersion area 14 is in a state just before being
delivered from CD bar 46 to wafer stage WST.
[0157] Then, when both stages WST and MST further move to the +Y
direction while keeping their contact state (or proximity state)
and reach the position shown in FIG. 17, main controller 20 almost
simultaneously and individually detects the alignment marks (refer
to star-shaped marks in FIG. 17) arranged in five shot areas
(hereinafter, referred to as "second alignment shot areas") located
at positions that face alignment systems AL1 and AL2.sub.1 to
AL2.sub.4 respectively in FIG. 17, using five alignment systems AL1
and AL2.sub.1 to AL2.sub.4, and links the detection results of five
alignment systems AL1 and AL2.sub.1 to AL2.sub.4 and the
measurement values of the three encoders described above at the
time of the detection, and then stores them in the memory (not
shown). Incidentally, the simultaneous detection of the alignment
marks arranged in the five second alignment shot areas in this case
is also performed while changing the Z-position of wafer stage WST,
similar to the detection of the first alignment shot areas.
[0158] When performing this operation, because the X head that
faces X scale 39X.sub.1 and is also located on straight line LV
described above does not exist, main controller 20 controls the
position of wafer stage WST within the XY plane based on the
measurement values of X head 66 that faces X scale 39X.sub.2 (X
linear encoder 70D) and Y linear encoders 70E.sub.1 and
70F.sub.1.
[0159] As is described above, in the embodiment, positional
information (two-dimensional positional information) of eight
alignment marks in total can be detected at the point in time when
detection of the alignment marks in the second alignment shot areas
ends. Thus, at this stage, main controller 20 obtains the scaling
(the shot magnification) of wafer W by, for example, performing a
statistical computation based on the EGA method described above
using the positional information, and based on the computed shot
magnification, main controller 20 may also adjust optical
characteristics of projection optical system PL, for example, the
projection magnification. In the embodiment, optical
characteristics of projection optical system PL are adjusted by
controlling an adjustment device 68 (refer to FIG. 5) that adjusts
optical characteristics of projection optical system PL, by driving
a specific movable lens constituting projection optical system PL
or changing the pressure of gas inside the airtight room that is
formed between specific lenses constituting projection optical
system PL, or the like. That is, at the stage where alignment
systems AL1 and AL2.sub.1 to AL2.sub.4 finish detecting a
predetermined number (eight in this case) of marks on wafer W, main
controller 20 may control adjustment device 68 so as to make
adjustment device 68 adjust optical characteristics of projection
optical system FL based on the detection results. Incidentally, the
number of marks is not limited to eight, or to a half of the total
number of marks subject to detection, but may be, for example, the
number that is more than or equal to the number required for
computation of the scaling of the wafer or the like.
[0160] Next, after the simultaneous detection of the alignment
marks arranged in the five second alignment shot areas ends, main
controller 20 starts again movement to the +Y direction of both
stages WST and MST in the contact state (or proximity state), and
at the same time, starts the focus mapping (detection of positional
information (surface position information) of the wafer W surface
related to the Z-axis direction) using the multipoint AF system
(90a, 90b).
[0161] When performing the focus mapping, main controller 20
controls the position of wafer stage WST within the XY plane based
on X head 66 that faces X scale 39X.sub.2 (X linear encoder 70D)
and two Y heads 64y.sub.2 and 64y.sub.1 that face Y scales
39Y.sub.1 and 39Y.sub.2 respectively (Y linear encoders 70F.sub.1
and 70E.sub.1). Then, in a state of activating both the multipoint
AF system (90a, 90b) and the surface position sensor, main
controller 20 loads positional information (surface position
information) of the wafer stage WST surface (the surface of plate
28) related to the Z-axis direction measured by the surface
position sensor and positional information (surface position
information) of the wafer W surface related to the Z-axis direction
at a plurality of detection points detected by the multipoint AF
system (90a, 90b) at predetermined sampling intervals, while wafer
stage WST proceeds to the +Y direction, and makes three pieces of
information, which are two kinds of the loaded surface position
information and the measurement values of Y linear encoders
70F.sub.1 and 70E.sub.1 at the time of each sampling, correspond to
one another and sequentially stores them in the memory (not
shown).
[0162] When wafer stage WST reaches the position shown in FIG. 18
by movement to the +Y direction of both stages WST and MST in the
contact state (or proximity state) described above, main controller
20 stops wafer stage WST at that position, and continues the
movement of measurement stage MST to the +Y direction without
stopping it. Incidentally, when measurement stage MST reaches an
exposure start waiting position where measurement stage MST waits
until exposure is started on the side of wafer stage WST, main
controller 20 stops measurement stage MST at that position. Then,
main controller 20 almost simultaneously and individually detects
the alignment marks (refer to star-shaped marks in FIG. 18)
arranged in five shot areas (hereinafter, referred to as "third
alignment shot areas") that exist at positions that face alignment
systems AL1 and AL2.sub.1 to AL2.sub.4 in FIG. 18, using five
alignment systems AL1 and AL2.sub.1 to AL2.sub.4, links the
detection results of five alignment systems AL1 and AL2.sub.1 and
AL2.sub.4 and the measurement values of three encoders 70D,
70F.sub.1 and 70E.sub.1 at the time of the detection and stores
them in the memory (not shown). Incidentally, the simultaneous
detection of the alignment marks arranged in the five third
alignment shot areas in this case is also performed while changing
the Z-position of wafer stage WST, as is described above.
[0163] Next, main controller 20 starts movement of wafer stage WST
to the +Y direction. Then, when wafer stage WST reaches the
position shown in FIG. 19, main controller 20 immediately stops
wafer stage WST, and almost simultaneously and individually detects
the alignment marks (refer to star-shaped marks in FIG. 19)
arranged in three shot areas (hereinafter, referred to as "fourth
alignment shot areas") that face primary alignment system AL1 and
secondary alignment systems AL2.sub.2 and AL2.sub.3 respectively in
the state of FIG. 19, links the detection results of three
alignment systems AL1, AL2.sub.2 and AL2.sub.3 and the measurement
values of the three encoders described above at the time of the
detection, and stores them in the memory (not shown). Incidentally,
the simultaneous detection of the alignment marks arranged in the
three fourth alignment shot areas in this case is also performed
while changing the Z-position of wafer stage WST, as is described
above. At this point in time, the focus mapping is being continued.
Meanwhile, measurement stage MST is still waiting at the exposure
start waiting position described above. Then, main controller 20
performs a statistical computation, for example, based on the EGA
method described above using the detection results of the 16
alignment marks in total obtained as described above and the
corresponding measurement values of the four encoders, and computes
alignment information (coordinate values) of all the shot areas on
wafer W in an XY coordinate system that is defined by measurement
axes of the four encoders.
[0164] Next, main controller 20 continues the focus mapping while
moving wafer stage WST to the +Y direction again. Then, when the
detection beam from the multipoint AF system (90a, 90b) begins to
be away from the wafer W surface, as is shown in FIG. 20, main
controller 20 ends the focus mapping. At this point in time, main
controller 20 converts the surface position information regarding
each detection point of the multipoint AF system (90a, 90b) into
data with reference to the surface position information by the
surface position sensor that has been simultaneously loaded. After
that, based on the result of the foregoing wafer alignment (EGA),
the latest baselines of five alignment systems AL1 and AL2.sub.1 to
AL2.sub.4, and the like, main controller 20 performs exposure based
on a step-and-scan method in a liquid immersion exposure method and
sequentially transfers a reticle pattern on a plurality of shot
areas on wafer W. This state is shown in FIG. 21. Afterwards, the
similar operations are repeatedly performed to the remaining wafers
within the lot.
[0165] In this case, during the exposure operation, as can be seen
from the drawings such as FIG. 21 or FIG. 9, in order to perform
exposure to the substantially entire surface of wafer W, the
detection beam from irradiation system 69A of detection device
PDY.sub.1 is irradiated at least once to the entire area in the
Y-axis direction of scale 39Y.sub.2. Accordingly, in the case where
the scattered light is received by image sensor 67 that constitutes
detection device PDY.sub.1, main controller 20 judges that a
foreign substance exists on scale 39Y.sub.2, and from the
measurement result of encoder 70C at the time of the detection,
detects the Y-axis direction position (coordinate) of the foreign
substance. Further, based on the detection result by image sensor
67 and the measurement result of encoder 70B or 70D, main
controller 20 detects the position (coordinate) of the foreign
substance on scale 39Y.sub.2.
[0166] Further, the detection beam of detection device PDY.sub.2 is
also irradiated at least once to the entire area in the Y-axis
direction of scale 39Y.sub.1 during the exposure operation
similarly to the case of detection device PDY.sub.1, and therefore,
in the case where the scattered light is received by image sensor
67 that constitutes detection device PDY.sub.2, main controller 20
judges that a foreign substance exists on scale 39Y.sub.1, and from
the measurement result of encoder 70A at the time of the detection,
detects the position (coordinate) of the foreign substance.
Further, based on the detection result of detection device
PDY.sub.2 and the measurement result of encoder 70B or 70D, main
controller 20 executes judgment as to whether a foreign substance
exists or not, and detection of the position (coordinate) of the
foreign substance on scale 39Y.sub.1.
[0167] Further, during the exposure operation described above, as
is representatively shown in FIG. 21, detection device PDX.sub.1 or
PDX.sub.2 faces scale 39X.sub.1, and during the exposure operation,
the detection beam of detection device PDX.sub.1 or PDX.sub.2 is
irradiated at least once to the entire surface area of scale
39X.sub.1. Accordingly, main controller 20 executes judgment as to
whether a foreign substance exists or not, and detection of the
position (coordinate) of the foreign substance on scale 39X.sub.1
in the manner similar to the manner described above, using encoders
7013 and 70A or 70C and detection devices PDX.sub.1 and
PDX.sub.2.
[0168] Moreover, as is shown in FIGS. 12 to 14, while wafer stage
WST is moving from unloading position UP to loading position LP,
detection device PDX.sub.3 or PDX.sub.4 faces scale 39X.sub.2, and
either of the detection beam of detection device PDX.sub.3 or the
detection beam of detection device PDX.sub.4 is irradiated at least
once to the entire surface area of scale 39X.sub.2, and therefore
main controller 20 executes judgment as to whether a foreign
substance exists or not, and detection of the position (coordinate)
of the foreign substance on scale 39X.sub.2 using detection device
PDX.sub.3 or PDX.sub.4 and encoders 70D and Y-axis interferometer
16.
[0169] Further, as is shown in FIGS. 9 and 18, in the case where
liquid immersion area 14 does not exists on measurement stage MST
and measurement stage MST can freely move, main controller 20 moves
measurement stage MST to a position where reference grating 52 on
CD bar 46 faces detection device PDX.sub.1 or PDX.sub.2, and
executes judgment as to whether a foreign substance exists on
reference grating 52 or not, and detection of the position
(coordinate) of the foreign substance on reference grating 52 using
detection device PDX.sub.1 or PDX.sub.2.
[0170] Incidentally, not limited to the cases described above, but
for example, as is shown in FIGS. 15 to 19, also while the
alignment operation using alignment systems AL1 and AL2.sub.4 to
AL2.sub.4 and the movement operation accompanying the alignment
operation are being performed, the detection beam of detection
device PDY.sub.1 (PDY.sub.2) is irradiated to the entire area of
scale 39Y.sub.2 (39Y.sub.1), and therefore, detection (inspection)
of foreign substance on the upper sauce of scale 39Y.sub.2
(39Y.sub.1) may also be performed using detection device PDY.sub.1
(PDY.sub.2) during these operations. That is, the foreign substance
detection operation may be carried out at least partially in
parallel with another operation that is different from the exposure
operation. Incidentally, the foreign substance detection operation
may be carried out at least partially by itself. In this case, the
placement and/or the number of the detection devices for foreign
substance may be different from that/those in FIG. 3.
[0171] In the embodiment, in the case where the judgment is made
that a foreign substance exists on the scale surface as a result of
the above-described detection (inspection) of foreign substance,
based on the foreign substance detection result, main controller 20
judges whether to perform cleaning (or replacement) of the scale or
to continue the exposure operation (including the alignment
operation and the like) in accordance with, for example, the
operation status or the like, and in the case where the exposure
operation (including the alignment operation and the like) is
continued, the heads are selected avoiding the foreign substance so
that the head that faces the foreign substance is not used during
the operation. The heads that do not face the foreign substance are
used by, for example, selecting the heads of three head units that
do not face the foreign substance out of the four head units, or by
changing the switching timing of heads in each head unit. That is,
based on the foreign substance detection result, an area where the
foreign substance exists on the scale is identified as a
non-measurement area to which measurement by encoder system 200
cannot be performed or with which measurement value becomes
abnormal. Furthermore, in an operation in which position
measurement of wafer stage WST by encoder system 200 is performed,
for example, in the exposure operation, while selecting three
encoder heads that do not face the non-measurement area according
to the position of wafer stage WST, the position of wafer stage WST
is controlled using the selected three encoder heads. Then, for
example, at this stage, wafer stage WST is moved via stage drive
system 124, so that a portion where the foreign substance of the
scale exits is located immediately below projection unit PU when
exposure to wafer W mounted on wafer stage WST ends. That is, a
portion of the scale that includes the foreign substance moves into
liquid immersion area 14. Since local liquid immersion device 8
performs supply and recovery of liquid Lq in parallel, the foreign
substance that has moved into liquid immersion area 14 is recovered
together with liquid Lq. With this operation, the foreign substance
on the scale is removed (cleaned).
[0172] Then, when the foreign substance removal described above is
finished, main controller 20 returns wafer stage WST to the
previous position and executes the continuation of the operation
that has been performed partway. In this case, because exposure of
wafer W and removal of foreign substance are completed, wafer stage
WST is moved to unloading position UP to perform wafer exchange,
and the exposure sequence is continued. Incidentally, the foreign
substance removal is to be performed immediately after exposure of
wafer W ends, but for example, when the exposure sequence ends, the
foreign substance removal sequence may be carried out, that is, the
foreign substance removal operation can be started. Further, the
non-measurement area of the scale identified from the foreign
substance detection result may be only an area where the foreign
substance exists but may also be an area larger than the foreign
substance.
[0173] Meanwhile, in the case where the judgment is made that the
cleaning (or replacement) of the scale should be performed based on
the foreign substance detection result, main controller 20
immediately discontinues the exposure operation and performs the
necessary process. Incidentally, the necessary process may be
started when exposure of wafer W ends, without immediately stopping
the exposure operation. Further, in the case where the foreign
substance detection operation is performed prior to the exposure
operation, whether or not the exposure operation can be carried out
may be judged based on the foreign substance detection result. As
an example, in the case where no foreign substance exists on the
scale, or measurement by the encoder system can be performed even
when a foreign substance exists, or three heads can be selected
avoiding the foreign substance (the non-measurement area), the
judgment is made that the exposure operation can be carried out. On
the other hand, in the case where the control accuracy of wafer
stage WST (or the alignment accuracy of the wafer with respect to
the reticle pattern) exceeds a permissible value due to measurement
defect of the encoder system owing to the foreign substance, the
judgment is made that the exposure operation cannot be carried out
and the necessary process (the cleaning or replacement of the
scale) is carried out.
[0174] As is described above, according to the embodiment, the
surface state of the scales (the existence state of foreign
substance) is detected by irradiating the detection beam from
irradiation system 69A of detection devices PDX.sub.1 to PDX.sub.4,
PDY.sub.1 and PDY.sub.2 to scales 39X.sub.1, 39X.sub.2, 39Y.sub.1
and 39Y.sub.2 that are used to measure the position of wafer stage
WST, and detecting the detection beam via scales 39X.sub.1,
39X.sub.2, 39Y.sub.1 and 39Y.sub.2 (scattered on scales 39X.sub.1,
39X.sub.2, 39Y.sub.1 and 39Y.sub.2) by photodetection system 69B,
and therefore detection of the surface state can be performed
contactlessly with respect to the scales.
[0175] Further, according to the embodiment, the detection device
can detect the surface state of the scales (the existence state of
foreign substance), and therefore by performing position
measurement of wafer stage WST using the scales taking the surface
state into consideration, the highly precise position control of
wafer stage WST can be performed. In particular, in the embodiment,
in the case where a foreign substance is found as a result of the
detection of the detection device, the exposure operation is to be
performed after the foreign substance is removed, and thus the
highly precise position control of wafer stage WST can be performed
without being affected by the foreign substance.
[0176] Further, since the highly precise position control of wafer
stage WST can be performed as is described above, exposure to wafer
W held on wafer stage WST can be performed with high accuracy.
[0177] Further, according to the embodiment, the detection device
also detects the surface state (the existence state of foreign
substance) of reference gratings 52 on CD bar 46, and therefore,
the relative positional relation of (the detection center of)
secondary alignment system AL2.sub.n with reference to (the
detection center of) primary alignment system AL1 can be detected
with high accuracy, by performing the Sec-BCHK (interval) taking
the surface state into consideration (such as removing the foreign
substance). Besides, by performing exposure using this result,
exposure with high precision can be achieved.
[0178] Further, according to the embodiment, because the encoder
system that includes encoders 70A to 70D and the like having good
short term stability of measurement measures positional information
of wafer stage WST within the XY plane, the measurement can be
performed with high precision without being affected by air
fluctuations or the like.
[0179] Incidentally, in the embodiment described above, the
detection (the inspection) of foreign substance on the scale
surface is to be performed in parallel with operations of exposure
apparatus 100 such as the exposure operation, the alignment
operation, or the wafer exchange operation being performed, but the
present invention is not limited thereto. For example, when
exposure apparatus 100 is in the idle state (i.e. in the waiting
state in which none of operations such as the exposure operation,
the alignment operation, and the wafer exchange operation is
performed), the foreign substance inspection of the scale surface
may also be performed by moving wafer stage WST so that the
detection beam of the detection device is irradiated to the entire
area of the scale surface.
[0180] Further, the timing of the foreign substance inspection is
not limited to each time when exposing one wafer as in the
embodiment described above, but the foreign substance inspection
may also be performed at each predetermined interval, such as each
time when exposing a predetermined number of wafers or each time
when a predetermined period of time lapses, or the foreign
substance inspection may also be performed only when the
instruction by a worker is made (when the entry to an input device
(e.g. an inspection start button) of exposure apparatus 100 is
made). Further, the sequence may also be employed in which the
detection (the inspection) of foreign substance is performed at
each predetermined interval and the detection (the inspection) of
foreign substance is also performed when the instruction by a
worker is made. Alternatively, the sequence may also be employed in
which the foreign substance inspection of part of the scales is
performed when exposure to one wafer is performed and the foreign
substance inspection of the reaming part of the scales is performed
when exposure to the subsequent wafers is performed.
[0181] Incidentally, in the embodiment described above, in the case
where a foreign substance exists on the scale surface, the foreign
substance is to be removed (cleaned) using the liquid (the liquid
used for liquid immersion exposure) of local liquid immersion
device 8, but the present invention is not limited thereto, and for
example, the foreign substance may also be removed (cleaned) by
supplying another liquid (cleaning liquid), which is different from
the liquid used for liquid immersion exposure, from local liquid
immersion device 8 and using another liquid. As the cleaning
liquid, for example, a liquid having a higher oxygen concentration
than liquid Lq (e.g. a liquid to which degassing treatment is not
applied) may also be used. By performing cleaning using such a
liquid, it becomes possible to enhance oxidative degradation of the
foreign substance (e.g. the foreign substance made up of organic
substance). Incidentally, instead of such a liquid, the cleaning
may also be performed using, for example, a hydrogen peroxide
solution. Further, when performing the cleaning of the scale by the
liquid for liquid immersion exposure or for cleaning, for example,
optical cleaning by exposure light IL and/or ultrasonic cleaning
may also be used in combination.
[0182] Further, a device similar to local liquid immersion device 8
is arranged at exposure apparatus 100 and by using such a device,
the foreign substance on the scale may be removed. That is, a
cleaning device (a foreign substance removal device) that is at
least partially different from local liquid immersion device 8 may
be arranged at another position that is separate from projection
optical system PL (nozzle unit 32), for example, in a movement
route of wafer stage WST between the exposure position where
exposure light IL is irradiated via projection optical system PL
and the wafer exchange position.
[0183] Further, the present invention is not limited to the case
where the foreign substance is removed using liquid, but an
air-blow device that blows out air is arranged in exposure
apparatus 100 and by using the air blown out from the air-blow
device, the foreign substance on the scale surface may be removed.
Further, a heating device that removes the foreign substance by
heating it is arranged in exposure apparatus 100, and by using the
heating device, the foreign substance on the scale may be
removed.
[0184] Further, in the case where a foreign substance exists on the
scale surface, main controller 20 may only issue a warning to a
worker (an operator). In this case, the worker (the operator) may
stop the exposure apparatus to perform the maintenance operation.
Further, in the embodiment described above, only in the case where
more than a predetermined number of foreign substances exist, the
foreign substance removal operation may be performed (or the
warning may be issued). Or, only in the case where the exposure
operation cannot be carried out as is described above, the foreign
substance removal operation may be performed or the warning may be
issued.
[0185] Incidentally, in exposure apparatus 100 of the embodiment
described above, six detection devices (PDX.sub.1 to PDX.sub.4,
PDY.sub.1 and PDY.sub.2) are to be arranged as is shown in FIG. 3,
but the present invention is not limited thereto, and the number of
the detection devices may be any number as far as the detection
beam can be irradiated to the entire areas of the scales. Further,
the placement of the detection devices is not limited to the
placement of the embodiment described above as far as the detection
beam can be irradiated to the entire area of the scales.
Incidentally, an area to which foreign substance detection is
performed may be the entire surface of the scale or may be only an
area that is needed for position measurement of wafer stage
WST.
[0186] Incidentally, the case has been described so far where the
foreign substance on the scale is dust or a water drop, but the
foreign substance subject to detection of the detection devices is
not limited to dust or a water drop.
[0187] Further, in the embodiment described above, the case has
been described where detection of foreign substance on the scale
and various processes accompanying the detection are performed in
relation to the position measurement by the encoders of encoder
system 200, but this can be similarly applied to the Z sensors
described above that detects the scale as the detection surface.
That is, a process of selecting the Z sensor avoiding the foreign
substance (the non-measurement area), and a process of performing
cleaning or replacement of the scale if measurement defect of the Z
sensors occurs due the foreign substance, and the like can be
performed.
[0188] Further, in the embodiment described above, as is shown in
FIG. 7A, the encoder based on a diffraction interference method, in
which the light from the light source is branched by an optical
element such as the beam splitter and which is equipped with two
reflection mirrors that reflect the lights after being branched is
to be used as encoders 70A to 70F, but the present invention is not
limited thereto. An encoder based on a diffraction interference
method having three gratings, a pickup method, or a magnetic
method, or an encoder equipped with an light reflection block, as
is disclosed in, for example, Kokai (Japanese Unexamined Patent
Application Publication) No. 2005-114406 and the like, a so-called
scan encoder that is disclosed in, for example, U.S. Pat. No.
6,639,686 and the like may also be used. Further, in the embodiment
described above, head units 62A to 62D are to have a plurality of
heads placed at a predetermined distance, but the present invention
is not limited thereto, and a single head may also be employed that
is equipped with a light source that emits a light beam to an area
elongated in the pitch direction of the Y scale or the X scale, and
many photodetection elements densely disposed in the pitch
direction of the Y scale or the X scale that receive a reflected
light (a diffracted light) of the light beam from (the diffraction
grating of) the Y scale or the X scale.
[0189] Further, in the embodiment described above, the X heads and
the Y heads, that is, one-dimensional heads are used as the encoder
heads, but the present invention is not limited thereto, and a
two-dimensional head (a 2D head) whose measurement directions are
two orthogonal axes directions may also be used. Further, as the
encoder head, a head integral with the Z sensor may be used. In the
case of the integral head, a simple combination of the Z sensor and
the encoder head may be employed, but a single sensor equipped with
functions of the Z sensor and the encoder head may also be used as
the encoder head.
[0190] Further, in the embodiment described above, the case has
been described where second water repellent plate 28b is formed by
two plate-shaped members 29a and 29b stuck together, but the
present invention is not limited thereto, and second water
repellent plate 28b is composed of one plate-shaped member and the
diffraction grating may be directly formed on its upper surface.
Further, the diffraction grating is formed on the upper surface of
second water repellent plate 28b, and a protective member (e.g. a
thin film) that can transmit the detection light from head units
62A to 62D is arranged on the upper surface of water repellent
plate 28b, so that damage of the diffraction grating may be
prevented. Further, the diffraction grating is directly formed on
the wafer stage WST surface, and second water repellent plate 28b
may be arranged so as to cover the diffraction grating. Further, as
the diffraction grating, a diffraction grating having narrow slits
or grooves that are mechanically graved may also be employed, or
for example, a diffraction grating that is created by exposing
interference fringes on a photosensitive resin may also be
employed.
[0191] Further, in the embodiment described above, a reflective
diffraction grating is to be arranged on the upper surface of wafer
stage WST that is substantially parallel to the XY plane, but for
example, the reflective diffraction grating may be arranged on the
lower surface of wafer stage WST. In this case, head units 62A to
62D are placed on, for example, a base plate which the lower
surface of wafer stage WST faces. Moreover, as is disclosed in U.S.
Patent Applications Publications No. 2006/0227309, No.
2007/0052976, No. 2007/0263197 and the like, an encoder system, in
which encoder heads are arranged on wafer stage WST and scales are
arranged above wafer stage WST so as to face the encoder heads, may
also be employed. In this case, Z sensors may also be placed on
wafer stage WST and a predetermined surface (e.g. the surface) of
the scale may be used also as a reflection surface that reflects
measurement beams from the Z sensors. Further, for example, the
detection devices described above are arranged at a movable body
that is placed on base board 12, and while moving the movable body,
the foreign substance detection may be performed to the entire
surface of the scale. Furthermore, the foreign substance removal
device described above is also arranged at the movable body, and
the foreign substance of the scale may be removed based on the
foreign substance detection result. Incidentally, the movable body
may be measurement stage MST, or may be provided separately from
wafer stage WST and measurement stage MST. Further, the detection
devices and the foreign substance removal device described above
may be mounted on different movable bodies. Further, in the
embodiment described above, wafer stage WST is to be moved within a
horizontal plane, but wafer stage WST may also be moved within a
plane (e.g. a ZX plane) that intersects the horizontal plane.
Further, the position of reticle stage RST may be measured by the
encoder system. For example, in the case where reticle stage RST
moves two-dimensionally, an encoder system having a configuration
similar to the encoder system described above may also be arranged
to measure positional information of reticle stage RST. In this
case, for example, the detection devices described above may also
be used in order to detect a foreign substance on the scale (the
diffraction grating) arranged on reticle stage RST. In either case,
it is possible to detect a foreign substance on the scale by
arranging the detection devices of the embodiment described above
at the position facing the diffraction grating (the scale).
[0192] Further, a configuration of the detection device that
detects a foreign substance is not limited to the configuration in
the embodiment described above (FIG. 4A), but other configurations
may also be employed as far as a detection device detects a foreign
substance by irradiating the detection beam to the scale and
receiving the detection beam via the scale. For example, the
multipoint AF system described above may also be used as the
detection device, and in this case, the detection devices described
above do not have to be provided separately from the multipoint AF
system. Further, for example, in the cases such as when by using
the Z sensors described above or the like, the Z-position of the
surface (including the scale surface) of areas other than the area
where wafer W is mounted on the upper surface of wafer stage WST is
detected, that is, the Z-position of the measurement surface of the
Z sensor is detected, the detection device may detect a foreign
substance not only on the scale but also on the surface (the
measurement surface) of the areas other than the area where wafer W
is mounted on the upper surface of wafer stage WST. With this
operation, a foreign substance on the measurement surface can be
detected by a detection device that is the same as or different
from each of the detection devices of the embodiment described
above, similarly to the case where a foreign substance on the scale
is detected by each of the detection devices in the embodiment
described above, which makes it possible to gain the effect
equivalent to the embodiment described above.
[0193] Incidentally, in the embodiment described above, the lower
surface of nozzle unit 32 and the lower end surface of the tip
optical element of projection optical system FL are to be
substantially flush. However, the present invention is not limited
to thereto, and for example, the lower surface of nozzle unit 32
may also be placed closer to the image plane of projection optical
system FL (i.e. to the wafer) than the outgoing surface of the tip
optical element. That is, the constitution of local liquid
immersion device 8 is not limited to the above-described
constitution, and the constitutions can be used, which are
described in, for example, European Patent Application Publication
No. 1 420 298, the pamphlet of International Publication No.
2004/055803, the pamphlet of International Publication No.
2004/057590, the pamphlet of International Publication No.
2005/029559 (the corresponding U.S. Patent Application Publication
No. 2006/0231206), the pamphlet of International Publication No.
2004/086468 (the corresponding U.S. Patent Application Publication
No. 2005/0280791), Kokai (Japanese Unexamined Patent Application
Publication) No. 2004-289126 (the corresponding U.S. Pat. No.
6,952,253), and the like. Further, as is disclosed in the pamphlet
of International Publication No. 2004/019128 (the corresponding
U.S. Patent Application Publication No. 2005/0248856), the optical
path on the object plane side of the tip optical element may also
be filled with liquid, in addition to the optical path on the image
plane side of the tip optical element. Furthermore, a thin film
that is lyophilic and/or has dissolution preventing function may
also be formed on the partial surface (including at least a contact
surface with liquid) or the entire surface of the tip optical
element. Incidentally, quartz has a high affinity for liquid, and
also needs no dissolution preventing film, while in the case of
fluorite, at least a dissolution preventing film is preferably
formed.
[0194] Incidentally, in the embodiment described above, pure water
(water) is to be used as liquid, however, the present invention is
not limited thereto as matter of course.
[0195] Further, in the embodiment described above, the recovered
liquid may be reused, and in this case, a filter that removes
impurities from the recovered liquid is preferably arranged in a
liquid recovery device, a recovery pipe or the like.
[0196] Further, in the embodiment described above, the case has
been described where the exposure apparatus is a liquid immersion
type exposure apparatus, but the present invention is not limited
thereto and can also be employed in a dry type exposure apparatus
that performs exposure of wafer W without liquid (water).
[0197] Incidentally, in the embodiment described above, the case
has been described where the present invention is applied to the
exposure apparatus that is equipped with all of wafer stage WST (a
movable body), measurement sage MST (another movable body), the
alignment systems (AL1, AL2.sub.1 to AL2.sub.4), the multipoint AF
system (90a, 90b), interferometer system 118, encoder system 200
and the like, but the present invention is not limited thereto. For
example, the present invention can also be applied to an exposure
apparatus in which measurement stage MST or the like is not
arranged. Further, it is a matter of course that both of the
interferometer system and the encoder system do not always have to
be arranged. That is, only the encoder system may be arranged.
[0198] Incidentally, in the embodiment described above, the case
has been described where the FIA system is employed as the
alignment system, but the present invention is not limited thereto,
and for example, an alignment sensor, which irradiates a coherent
detection light to a subject mark and detects a scattered light or
a diffracted light generated from the subject mark or makes two
diffracted lights (e.g. diffracted lights of the same order or
diffracted lights being diffracted in the same direction) generated
from the subject mark interfere and detects an interference light,
can naturally be used by itself or in combination as needed.
Further, five alignment systems AL1 and AL2.sub.1 to AL2.sub.4 are
to be arranged in the embodiment described above, but the number of
alignment systems is not limited to five, and may be the number
more than or equal to two and less than or equal to four, or may be
the number more than or equal to six, or may be the even number,
not the odd number. Moreover, one alignment system may be arranged,
and alignment system (s) may be either movable or fixed.
[0199] Further, in the embodiment described above, the case has
been described where the present invention is applied to a scanning
exposure apparatus based on a step-and-scan method or the like, but
the present invention is not limited thereto, and may also be
applied to a static exposure apparatus such as a stepper. Even with
the stepper or the like, by measuring the position of a stage on
which an object subject to exposure is mounted using encoders,
occurrence of position measurement error caused by air fluctuations
can substantially be nulled likewise. In this case, it becomes
possible to set the position of the stage with high precision based
on correction information used to correct the short-term
fluctuation of the measurement value of the encoders using the
measurement values of the interferometers and the measurement
values of the encoders, and as a consequence, highly accurate
transfer of a reticle pattern onto the object can be performed.
Further, the present invention can also be applied to a reduced
projection exposure apparatus based on a step-and-stitch method
that synthesizes a shot area and a shot area, an exposure apparatus
based on a proximity method, a mirror projection aligner, or the
like. Moreover, the present invention can also be applied to a
multi-stage type exposure apparatus equipped with a plurality of
wafer stages, as is disclosed in, for example, Kokai (Japanese
Unexamined Patent Application Publications) No. 10-163099 and No.
10-214783 (the corresponding U.S. Pat. No. 6,590,634), Kohyo
(published Japanese translation of International Publication for
Patent Application) No. 2000-505958 (the corresponding U.S. Pat.
No. 5,969,441), the U.S. Pat. No. 6,208,407, and the like.
[0200] Further, the magnification of the projection optical system
in the exposure apparatus in the embodiment described above is not
only a reduction system, but also may be either an equal magnifying
system or a magnifying system, and projection optical system PL is
not only a dioptric system, but also may be either a catoptric
system or a catadioptric system, and in addition, the projected
image may be either an inverted image or an upright image.
Moreover, exposure area IA to which illumination light IL is
irradiated via projection optical system PL is an on-axis area that
includes optical axis AX within the field of projection optical
system PL. However, for example, as is disclosed in the pamphlet of
International Publication No. 2004/107011, the exposure area may
also be an off-axis area that does not include optical axis AX,
similar to a so-called inline type catadioptric system, in part of
which an optical system (a catoptric system or a catadioptric
system) that has a plurality of reflection surfaces and forms an
intermediate image at least once is arranged, and which has a
single optical axis. Further, the illumination area and exposure
area described above are to have a rectangular shape, but the shape
is not limited to rectangular, and may also be circular arc,
trapezoidal, parallelogram or the like.
[0201] Incidentally, the light source of the exposure apparatus in
the embodiment described above is not limited to the ArF excimer
laser, but a pulsed laser light source such as a KrF excimer laser
(output wavelength: 248 nm), an F.sub.2 laser (output wavelength:
157 nm), an Ar.sub.2 laser (output wavelength: 126 nm) or a
Kr.sub.2 laser (output wavelength: 146 nm), or an extra-high
pressure mercury lamp that generates an emission line such as a
g-line (wavelength: 436 nm) or an i-line (wavelength: 365 nm) can
also be used. Further, a harmonic wave generation device of a YAG
laser or the like can also be used. Besides, as is disclosed in,
for example, the pamphlet of International Publication No.
1999/46835 (the corresponding U.S. Pat. No. 7,023,610), a harmonic
wave, which is obtained by amplifying a single-wavelength laser
beam in the infrared or visible range emitted by a DFB
semiconductor laser or fiber laser as vacuum ultraviolet light,
with a fiber amplifier doped with, for example, erbium (or both
erbium and ytterbium), and by converting the wavelength into
ultraviolet light using a nonlinear optical crystal, may also be
used.
[0202] Further, in the embodiment described above, illumination
light IL of the exposure apparatus is not limited to the light
having a wavelength more than or equal to 100 nm, and it is
needless to say that the light having a wavelength less than 100 nm
may be used. For example, in recent years, in order to expose a
pattern less than or equal to 70 nm, an EUV exposure apparatus that
makes an SOR or a plasma laser as a light source generate an EUV
(Extreme Ultraviolet) light in a soft X-ray range (e.g. a
wavelength range from 5 to 15 nm), and uses a total reflection
reduction optical system designed under the exposure wavelength
(e.g. 13.5 nm) and the reflective mask has been developed. In the
EUV exposure apparatus, the arrangement in which scanning exposure
is performed by synchronously scanning a mask and a wafer using a
circular arc illumination can be considered, and therefore, the
present invention can also be suitably applied to such an exposure
apparatus. Besides, the present invention can also be applied to an
exposure apparatus that uses charged particle beams such as an
electron beam or an ion beam.
[0203] Further, in the embodiment described above, a transmissive
type mask (reticle), which is a transmissive substrate on which a
predetermined light shielding pattern (or a phase pattern or a
light attenuation pattern) is formed, is used. Instead of this
reticle, however, as is disclosed in, for example, U.S. Pat. No.
6,778,257, an electron mask (which is also called a variable shaped
mask, an active mask or an image generator, and includes, for
example, a DMD (Digital Micromirror Device) that is a type of a
non-emission type image display device (a spatial light modulator)
or the like) on which a light-transmitting pattern, a reflection
pattern, or an emission pattern is formed according to electronic
data of the pattern that is to be exposed may also be used.
[0204] Further, as is disclosed in, for example, the pamphlet of
International Publication No. 2001/035168, the present invention
can also be applied to an exposure apparatus (a lithography system)
that forms line-and-space patterns on a wafer by forming
interference fringes on the wafer.
[0205] Moreover, the present invention can also be applied to an
exposure apparatus that synthesizes two reticle patterns on a wafer
via a projection optical system and almost simultaneously performs
double exposure of one shot area on the wafer by one scanning
exposure, as is disclosed in, for example, Kohyo (published
Japanese translation of International Publication for Patent
Application) No. 2004-519850 (the corresponding U.S. Pat. No.
6,611,316).
[0206] Further, an apparatus that forms a pattern on an object is
not limited to the exposure apparatus (the lithography system)
described above, and for example, the present invention can also be
applied to an apparatus that forms a pattern on an object based on
an ink-jet method.
[0207] Incidentally, an object on which a pattern should be formed
(an object subject to exposure to which an energy beam is
irradiated) in the above-described embodiment is not limited to a
wafer, but may be other objects such as a glass plate, a ceramic
substrate, a film member, or a mask blank.
[0208] The usage of the exposure apparatus is not limited to the
exposure apparatus used for manufacturing semiconductor devices,
but the present invention can be widely applied also to, for
example, an exposure apparatus for manufacturing liquid crystal
display devices which transfers a liquid crystal display device
pattern onto a square-shaped glass plate, and to an exposure
apparatus for manufacturing organic ELs, magnetic heads, imaging
devices (such as CCDs), micromachines, DNA chips or the like.
Further, the present invention can also be applied to an exposure
apparatus that transfers a circuit pattern onto a glass substrate
or a silicon wafer not only when producing microdevices such as
semiconductor devices, but also when producing a reticle or a mask
used in an exposure apparatus such as an optical exposure
apparatus, an EUV exposure apparatus, an X-ray exposure apparatus,
and an electron beam exposure apparatus.
[0209] Further, the exposure apparatus (the pattern formation
apparatus) in the embodiment described above is manufactured by
assembling various subsystems, which include the respective
constituents that are recited in the claims of the present
application, so as to keep predetermined mechanical accuracy,
electrical accuracy and optical accuracy. In order to secure these
various kinds of accuracy, before and after the assembly,
adjustment to achieve the optical accuracy for various optical
systems, adjustment to achieve the mechanical accuracy for various
mechanical systems, and adjustment to achieve the electrical
accuracy for various electric systems are performed. A process of
assembling various subsystems into the exposure apparatus includes
mechanical connection, wiring connection of electric circuits,
piping connection of pressure circuits, and the like among various
types of subsystems. Needless to say, an assembly process of
individual subsystem is performed before the process of assembling
the various subsystems into the exposure apparatus. When the
process of assembling the various subsystems into the exposure
apparatus is completed, a total adjustment is performed and various
kinds of accuracy as the entire exposure apparatus are secured.
Incidentally, the making of the exposure apparatus is preferably
performed in a clean room where the temperature, the degree of
cleanliness and the like are controlled.
[0210] Incidentally, the above disclosures of the various
publications, the pamphlets of the International Publications, and
the U.S. patent application Publications, and the U.S. patents that
are cited in the embodiment described above and related to exposure
apparatuses and the like are each incorporated herein by
reference.
[0211] Electron devices such as semiconductor devices are
manufactured through the following steps: a step where the
function/performance design of a device is performed; a step where
a reticle based on the design step is manufactured; a step where a
wafer is manufactured using materials such as silicon; a
lithography step where a pattern of the mask (the reticle) is
transferred onto the wafer by the exposure apparatus (the pattern
formation apparatus) of the embodiment described above; a
development step where the exposed wafer is developed; an etching
step where an exposed member of an area other than the area where
resist remains is removed by etching; a resist removing step where
the resist that is no longer necessary when the etching is
completed is removed; a device assembly step (including a dicing
process, a bonding process, and a packaging process); an inspection
step; and the like. In this case, in the lithography step, the
exposure method described above is executed using the exposure
apparatus (the pattern formation apparatus) of the embodiment
described above and device patterns are formed on the wafer, and
therefore, highly-integrated devices can be manufactured with high
productivity.
[0212] While the above-described embodiment of the present
invention is the presently preferred embodiment thereof, those
skilled in the art of lithography systems will readily recognize
that numerous additions, modifications, and substitutions may be
made to the above-described embodiment without departing from the
spirit and scope thereof. It is intended that all such
modifications, additions, and substitutions fall within the scope
of the present invention, which is best defined by the claims
appended below.
* * * * *