U.S. patent application number 16/256026 was filed with the patent office on 2019-05-23 for exposure apparatus, exposure method, and method for producing device.
This patent application is currently assigned to NIKON CORPORATION. The applicant listed for this patent is NIKON CORPORATION. Invention is credited to Yuho KANAYA, Takahiro MASADA, Tadashi NAGAYAMA, Masahiko YASUDA.
Application Number | 20190155168 16/256026 |
Document ID | / |
Family ID | 34436914 |
Filed Date | 2019-05-23 |
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United States Patent
Application |
20190155168 |
Kind Code |
A1 |
YASUDA; Masahiko ; et
al. |
May 23, 2019 |
EXPOSURE APPARATUS, EXPOSURE METHOD, AND METHOD FOR PRODUCING
DEVICE
Abstract
An exposure apparatus includes (i) a projection optical system,
(ii) a substrate stage having a substrate holder on which a
substrate is held, which is movable while holding the substrate
with the substrate holder, and (iii) a reference member having a
first reference and a second reference for performing an alignment
process, the reference member being provided on the substrate
stage. At least part of an upper surface of the reference member
includes a liquid repellent material. The substrate is aligned
based on information obtained from the alignment process. The
substrate is exposed through liquid in a liquid immersion area
formed locally on an upper surface of the substrate.
Inventors: |
YASUDA; Masahiko;
(Itabashi-ku, JP) ; MASADA; Takahiro; (Fukaya-shi,
JP) ; KANAYA; Yuho; (Kumagaya-shi, JP) ;
NAGAYAMA; Tadashi; (Toshima-ku, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIKON CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
NIKON CORPORATION
Tokyo
JP
|
Family ID: |
34436914 |
Appl. No.: |
16/256026 |
Filed: |
January 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15199195 |
Jun 30, 2016 |
10209623 |
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16256026 |
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14693320 |
Apr 22, 2015 |
9383656 |
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15199195 |
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13354899 |
Jan 20, 2012 |
9063438 |
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14693320 |
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11399537 |
Apr 7, 2006 |
8130361 |
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13354899 |
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PCT/JP2004/015332 |
Oct 12, 2004 |
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11399537 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F 7/70716 20130101;
G03F 7/70141 20130101; G03F 7/70341 20130101; G03F 9/7088
20130101 |
International
Class: |
G03F 7/20 20060101
G03F007/20; G03F 9/00 20060101 G03F009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 9, 2003 |
JP |
2003-350628 |
Feb 20, 2004 |
JP |
2004-045103 |
Claims
1. An exposure apparatus comprising: a projection optical system; a
substrate stage having a substrate holder on which a substrate is
held, which is movable while holding the substrate with the
substrate holder; and a reference member having a first reference
and a second reference for performing an alignment process, the
reference member being provided on the substrate stage, wherein: at
least part of an upper surface of the reference member includes a
liquid repellent material, the substrate is aligned based on
information obtained from the alignment process, and the substrate
is exposed through liquid in a liquid immersion area formed locally
on an upper surface of the substrate.
2. The exposure apparatus according to claim 1, wherein the
substrate stage is movable to effect a switching between a wet
state in which the liquid is disposed on the reference member and a
dry state in which the liquid is not disposed on the reference
member.
3. The exposure apparatus according to claim 1, wherein the
substrate stage has a recess in which the substrate is held, and
the substrate stage has an upper surface which is substantially
flush with an upper surface of the reference member, and the
substrate is held in the recess such that the upper surface of the
substrate is substantially flush with the upper surface of the
substrate stage.
4. The exposure apparatus according to claim 1, wherein the
substrate stage has a recess in which the reference member is
arranged.
5. The exposure apparatus according to claim 1, wherein the
substrate stage is movable from a first state in which the upper
surface of the reference member is opposed to the projection
optical system to a second state in which the upper surface of the
substrate is opposed to the projection optical system, while the
liquid is retained on an image plane side of the projection optical
system.
6. The exposure apparatus according to claim 5, wherein the liquid
is retained between the reference member and the projection optical
system to obtain information for aligning the image and the
substrate.
7. The exposure apparatus according to claim 1, wherein the
substrate stage is movable from a first state in which the upper
surface of the substrate is opposed to the projection optical
system to a second state in which the upper surface of the
reference member is opposed to the projection optical system, while
the liquid is retained on an image plane side of the projection
optical system.
8. The exposure apparatus according to claim 7, wherein the liquid
is retained between the reference member and the projection optical
system to obtain information for aligning the image and the
substrate.
9. The exposure apparatus according to claim 1, wherein the
projection optical system projects an image of a pattern of a mask
illuminated with illumination light.
10. The exposure apparatus according to claim 9, further comprising
a first detecting system arranged apart from the projection optical
system, which detects an alignment mark on the substrate held by
the substrate stage not through the liquid and which detects the
first reference of the reference member not through the liquid.
11. The exposure apparatus according to claim 10, wherein the first
reference of the reference member is detected with the first
detecting system before the reference member comes into contact
with the liquid.
12. The exposure apparatus according to claim 10, wherein the first
reference of the reference member is detected with the first
detecting system before the liquid is retained between the
reference member and the projection optical system.
Description
CROSS-REFERENCE
[0001] This is a divisional of U.S. patent application Ser. No.
15/199,195 filed Jun. 30, 2016, which in turn is a divisional of
U.S. patent application Ser. No. 14/693,320 filed Apr. 22, 2015
(now U.S. Pat. No. 9,383,656), which is a divisional of U.S. patent
application Ser. No. 13/354,899 filed Jan. 20, 2012 (now U.S. Pat.
No. 9,063,438), which is a divisional of U.S. patent application
Ser. No. 11/399,537 filed Apr. 7, 2006 (now U.S. Pat. No.
8,130,361), which is a continuation of International Application
No. PCT/JP2004/015332 filed Oct. 12, 2004 claiming the convention
priority of Japanese patent Application No. 2003-350628 filed on
Oct. 9, 2003 and No. 2004-045103 filed on Feb. 20, 2004. The
disclosures of each of the prior applications are incorporated
herein by reference in their entireties.
TECHNICAL FIELD
Field of the Invention
[0002] The present invention relates to an exposure apparatus, an
exposure method, and a method for producing a device in which a
substrate is exposed with a pattern via a projection optical system
and a liquid,
Description of the Related Art
[0003] Microdevices such as semiconductor devices and liquid
crystal display devices are produced by means of the so-called
photolithography technique in which a pattern formed on a mask is
transferred onto a photosensitive substrate. The exposure
apparatus, which is used in the photolithography step, includes a
mask stage for supporting the mask and a substrate stage for
supporting the substrate. The pattern on the mask is transferred
onto the substrate via a projection optical system while
successively moving the mask stage and the substrate stage.
[0004] The microdevice is formed by overlaying a plurality of
layers of patterns on the substrate. Therefore, when the pattern
the second layer or the following layer is projected onto the
substrate to perform the exposure, it is important to accurately
perform the alignment process in which the pattern having been
already formed on the substrate is positionally adjusted to the
image of the pattern of the mask to be subjected to the exposure
next time. The alignment system includes the so-called TTL system
in which the projection optical system is used as a part of the
mark-detecting system, and the so-called off-axis system in which
an exclusive mark-detecting system is used not via the projection
optical system. In the case of these systems as described above,
the positional adjustment is not performed directly for the mask
and the substrate, but the positional adjustment is performed
indirectly by the aid of a reference mark provided in the exposure
apparatus (generally provided on the substrate stage). In
particular, in the case of the off-axis system, the baseline
measurement is performed to measure the baseline amount
(information) which is the distance (positional relationship)
between the detection reference position of the exclusive
mark-detecting system and the projection position of the image of
the pattern of the mask in a coordinate system which defines the
movement of the substrate stage. When the overlay exposure is
performed for the substrate, for example, the following operation
is performed. That is, an alignment mark, which is formed in the
shot area as the exposure objective area on the substrate, is
detected by the mark-detecting system to determine the position
information (deviation or discrepancy) of the shot area with
respect to the detection reference position of the mark-detecting
system. The substrate stage is moved from the position of the
substrate stage obtained at that time by the baseline amount and
the amount of the deviation of the shot area determined by the
mark-detecting system. Accordingly, the projection position of the
image of the pattern of the mask and the shot area are subjected to
the positional adjustment, and the exposure is performed in this
state. In this way, the image of the pattern of the next mask can
be overlaid on the pattern which has been already formed on the
substrate (shot area).
[0005] In recent years, it is demanded to realize the higher
resolution of the projection optical system in order to respond to
the further advance of the higher integration of the device
pattern. As the exposure wavelength to be used is shorter, the
resolution of the projection optical system becomes higher. As the
numerical aperture of the projection optical system is larger, the
resolution of the projection optical system becomes higher.
Therefore, the exposure wavelength, which is used for the exposure
apparatus, is shortened year by year, and the numerical aperture of
the projection optical system is increased as well. The exposure
wavelength, which is dominantly used at present, is 248 nm of the
KrF excimer laser. However, the exposure wavelength of 193 nm of
the ArF excimer laser, which is shorter than the above, is also
practically used in some situations. When the exposure is
performed, the depth of focus (DOF) is also important in the same
manner as the resolution. The resolution R and the depth of focus
.delta. are represented by the following expressions
respectively.
R=k.sub.1.lamda./NA (1)
.delta.=.+-.k.sub.2.lamda./NA.sup.2 (2)
[0006] In the expressions, .lamda. represents the exposure
wavelength, NA represents the numerical aperture of the projection
optical system, and k.sub.1 and k.sub.2 represent the process
coefficients. According to the expressions (1) and (2), the
following fact is appreciated. That is, when the exposure
wavelength .lamda. is shortened and the numerical aperture NA is
increased in order to enhance the resolution R, then the depth of
focus .delta. narrowed.
[0007] If the depth of focus .delta. is too narrowed, it is
difficult to match the substrate surface with respect to the image
plane of the projection optical system. It is feared that the focus
margin is insufficient during the exposure operation. Accordingly,
the liquid immersion method has been suggested, which is disclosed,
for example, in International Publication No. 99/49504 as a method
for substantially shortening the exposure wavelength and widening
the depth of focus. In this liquid immersion method, the space
between the lower surface of the projection optical system and the
substrate surface is filled with a liquid such as water or any
organic solvent so that the resolution improved and the depth of
focus is magnified about n times by utilizing the fact that the
wavelength of the exposure light beam in the liquid is 1/n as
compared with that in the air (n represents the refractive index of
the liquid, which is about 1.2 to 1.6 in ordinary cases).
[0008] Of course, it is also important for the liquid immersion
exposure process that the positional adjustment is accurately
performed between the image of the pattern of the mask and the
respective shot areas on the substrate. It is important that the
baseline measurement and the alignment process can be performed
accurately when the positional adjustment between the substrate and
the image of the pattern of the mask is indirectly performed via
the reference mark as described above.
[0009] Further, not only the reference mark but also various types
of sensors and the like are arranged around the surface of the
substrate stage. When such an instrument is used, it is necessary
to avoid the leakage and the inflow of the liquid as much as
possible. Any inconvenience may possibly arise as well due to the
inflow of the liquid into the substrate stage. Therefore, it is
necessary to avoid the inflow of the liquid.
SUMMARY OF THE INVENTION
[0010] The present invention has been made taking the foregoing
circumstances into consideration, an object of which is to provide
an exposure apparatus and an exposure method which make it possible
to suppress the leakage and the inflow of the liquid. Another
object of the present invention is to provide an exposure apparatus
and an exposure method which make it possible to accurately perform
the alignment process even in the case of the liquid immersion
exposure. Still another object of the present invention is to
provide a method for producing a device using the exposure
apparatus, and a method for producing a device using the exposure
method.
[0011] In order to achieve the objects as described above, the
present invention adopts the following constructions.
[0012] According to a first aspect of the present invention, there
is provided an exposure apparatus which exposes a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
a substrate stage which is movable while holding the substrate; a
first detecting system which detects an alignment mark on the
substrate held by the substrate stage and which detects a reference
provided on the substrate stage; and a second detecting system
which detects the reference provided on the substrate stage via the
projection optical system; wherein the reference, which is provided
on the substrate stage, is detected not through the liquid by using
the first detecting system, and the reference, which is provided on
the substrate stage, is detected via the projection optical system
and the liquid by using the second detecting system to determine a
positional relationship between a detection reference position of
the first detecting system and a projection position of the image
of the pattern.
[0013] According to the present invention, when the reference on
the substrate stage is detected by the first detecting system, the
detection is performed not through the liquid. Accordingly, the
reference can be detected satisfactorily without being affected,
for example, by the temperature change of the liquid. It is
unnecessary to construct the first detecting system so that the
first detection signal is adapter to the liquid immersion. It is
possible to use any conventional detecting system as it is. When
the reference on the substrate stage is detected by using the
second detecting system, the detection is performed via the
projection optical system and the liquid while filling the space on
the image plane side of the projection optical system with the
liquid, in the same manner as in the liquid immersion exposure.
Accordingly, it is possible to accurately detect the projection
position of the image of the pattern on the basis of the detection
result The baseline amount (baseline information), which is the
positional relationship (distance) between the detection reference
position of the first detecting system and the projection position
of the image of the pattern, can be accurately determined on the
basis of the respective pieces of the position information about
the substrate stage during the detection operations of the first
and second detecting systems. The substrate (shot area) and the
image of the pattern of the mask can be accurately subjected to the
positional adjustment on the basis of the baseline amount when the
overlay exposure is performed for the substrate as well.
[0014] According to a second aspect of the present invention, there
is provided an exposure apparatus which exposes a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate,
a substrate stage which has a substrate holder for holding the
substrate and which is movable while holding the substrate on the
substrate holder; a first detecting system which detects an
alignment mark on the substrate held by the substrate stage; and a
second detecting system which detects a reference provided on the
substrate stage through the liquid; wherein the substrate or a
dummy substrate is arranged on the substrate holder when the
reference provided on the substrate stage is detected through the
liquid by using the second detecting system.
[0015] According to the present invention, it is possible to avoid
any inflow of a large amount of the liquid into the substrate
holder and/or into the substrate stage by arranging the substrate
or the dummy substrate on the substrate holder even when the
detection is performed in a state in which the liquid is arranged
or disposed on the reference. Therefore, it is possible to avoid
the occurrence of any inconvenience including, for example, the
trouble and the electric leakage of the electric equipment included
in the substrate stage and the rust of respective members included
in the substrate stage which would be otherwise caused by the
inflowed liquid.
[0016] According to a third aspect of the present invention, there
is provided an exposure apparatus which exposes a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
a reference member which has an upper surface having no difference
in level; and a detecting system which detects a reference formed
on the reference member in a state in which a space between an end
surface of the projection optical system and the upper surface of
the reference member is filled with the liquid.
[0017] According to the present invention, the upper surface of the
reference member has no difference in level. Therefore, any bubble
hardly remains at the reference mark portion (level difference
portion) on the reference member, for example, even when the dry
state is switched into the wet state. The liquid is prevented from
remaining at the mark portion as well when the wet state is
switched into the dry state. Therefore, it is also possible to
avoid the occurrence of any water trace (so-called water mark) on
the reference member.
[0018] According to a fourth aspect of the present invention, there
is provided an exposure apparatus which exposes a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
a substrate stage which has a substrate holder for holding the
substrate and which is movable while holding the substrate on the
substrate holder; a detector which detects whether or not the
substrate or a dummy substrate is held by the substrate holder; and
a control unit which changes a movable area of the substrate stage
depending on a detection result obtained by the detector.
[0019] According to the present invention, the movable area of the
substrate stage is determined depending on whether or not the
substrate or the dummy substrate is held by the substrate holder.
Therefore, it is possible to avoid the adhesion of the liquid to
the holding surface of the substrate holder, and it is possible to
avoid the inflow of the liquid into the substrate stage.
[0020] According to a fifth aspect of the present invention, there
is provided an exposure apparatus which exposes a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
a substrate stage which has a substrate holder for holding the
substrate and which is movable while holding the substrate on the
substrate holder; a liquid supply mechanism which supplies the
liquid; a detector which detects whether or not the substrate or a
dummy substrate is held by the substrate holder; and a control unit
which controls operation of the liquid supply mechanism on the
basis of a detection result obtained by the detector.
[0021] According to the present invention, the operation of the
liquid supply mechanism is controlled depending on whether or not
the substrate or the dummy substrate is held by the substrate
holder. Therefore, it is possible to avoid the adhesion of the
liquid to the holding surface of the substrate holder, and it is
possible to avoid the inflow of the liquid into the substrate
stage.
[0022] According to a sixth aspect of the present invention, there
is provided an exposure apparatus which exposes a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
a substrate stage which has a substrate holder for holding the
substrate and which is movable while holding the substrate on the
substrate holder; and a liquid supply mechanism which supplies the
liquid onto the substrate stage only when the substrate or a dummy
substrate is held on the substrate holder.
[0023] According to the present invention, the liquid supply
mechanism supplies the liquid onto the substrate stage only when
the substrate or the dummy substrate held on the substrate holder.
Therefore, it is possible to avoid the adhesion of the liquid to
the holding surface of the substrate holder, and it is possible to
avoid the inflow of the liquid into the substrate stage.
[0024] According to a seventh aspect of the present invention,
there is provided an exposure apparatus which exposes a substrate
by projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
a substrate stage which is movable while holding the substrate; and
a liquid immersion mechanism which forms a liquid immersion area on
the substrate stage only when the substrate or a dummy substrate is
held by the substrate stage.
[0025] According to the exposure apparatus of the seventh aspect,
the liquid immersion mechanism does not form the liquid immersion
area on the substrate stage when the substrate or the dummy
substrate is not held on the substrate stage. Therefore, it is
possible to effectively avoid the inflow of the liquid into the
substrate stage.
[0026] According to an eighth aspect of the present invention,
there is provided an exposure apparatus which exposes a substrate
by projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
and a substrate stage which has a recess for holding the substrate
and a flat portion arranged around the recess, the flat portion
being substantially flush with a surface of the substrate held by
the recess; wherein an object is arranged in the recess on the
substrate stage, and a liquid immersion area is formed on the
substrate stage only when a surface of the object is substantially
flush with the flat portion.
[0027] According to the exposure apparatus of the eighth aspect,
the liquid immersion area is not formed on the substrate stage when
the object is not accommodated in the recess of the substrate stage
or when the object is not accommodated in the recess reliably.
Accordingly, it is possible to effectively avoid the inflow of the
liquid into the substrate stage.
[0028] According to a ninth aspect of the present invention, there
is provided an exposure apparatus which exposes a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure apparatus comprising a projection optical
system which projects the image of the pattern onto the substrate;
a stage which is movable on an image plane side of the projection
optical system; a first detecting system which detects an alignment
mark on the substrate and which detects a reference provided on the
stage; and a second detecting system which detects the reference
provided on the stage via the projection optical system; wherein
the reference provided on the stage is detected not through the
liquid by using the first detecting system, and the reference
provided on the stage is detected via the projection optical system
and the liquid by using the second detecting system to determine a
positional relationship between a detection reference position of
the first detecting system and a projection position of the image
of the pattern.
[0029] According to the ninth aspect of the present invention, it
is possible to accurately perform the positional adjustment for the
substrate (shot area) and the image of the pattern.
[0030] According to a tenth aspect of the present invention, there
is provided an exposure method for exposing a substrate by
projecting an image of a pattern onto the substrate via a
projection optical system and a liquid; the exposure method
comprising detecting position information about an alignment mark
on the substrate by using a first detecting system; detecting
position information about a reference on a substrate stage which
holds the substrate, by using the first detecting system; and
detecting the reference on the substrate stage via the projection
optical system and the liquid by using a second detecting system
after completion of both of detection of the position information
about the alignment mark and detection of the position information
about the reference on the substrate stage by the first detecting
system; wherein a relationship between a detection reference
position of the first detecting system and a projection position of
the image of the pattern is determined on the basis of a detection
result of the position information about the alignment mark
obtained by the first detecting system, a detection result of the
position information about the reference on the substrate stage
obtained by the first detecting system, and a detection result of
the position information about the reference on the substrate stage
obtained by the second detecting system, and the image of the
pattern and the substrate are subjected to positional adjustment to
successively project the image of the pattern onto each of a
plurality of shot areas on the substrate to expose the
substrate.
[0031] According to this exposure method, the position information
about the plurality of shot areas on the substrate is firstly
determined by detecting the alignment mark on the substrate by the
first detecting system not through the liquid. Subsequently, the
reference on the substrate stage is detected not through the liquid
to determine the position information thereof. Subsequently, the
space on the image plane side of the projection optical system is
filled with the liquid and the projection position of the image of
the pattern is determined by detecting the reference on the
substrate stage by the second detecting system via the projection
optical system and the liquid. The baseline amount, which is the
positional relationship (distance) between the detection reference
position of the first detecting system and the projection position
of the image of the pattern, is accurately determined. After that,
the space between the projection optical system and the substrate
is filled with the liquid to perform the liquid immersion exposure
for the substrate. Therefore, it is possible to decrease the number
of times of the switching operations between the dry state in which
the space on the image plane side of the projection optical system
is not filled with the liquid and the wet state in which the space
on the image plane side of the projection optical system is filled
with the liquid. Thus, it is possible to improve the throughput.
The operation for detecting the reference by the first detecting
system and the operation for detecting the reference by the second
detecting system via the projection optical system and the liquid
are continuously performed. Therefore, it is possible to avoid the
inconvenience which would be otherwise caused such that the
detection state, which is brought about during the operation for
detecting the reference by the second detecting system, is greatly
varied from the detection state which is brought about during the
operation for detecting the reference by the first detecting
system, and the baseline amount, which is the positional
relationship between the detection reference position of the first
detecting system and the projection position of the image of the
pattern, cannot be measured accurately. The reference can be
satisfactorily detected without being affected, for example, by the
temperature change of the liquid by performing the detection not
through the liquid when the reference on the substrate stage is
detected by the first detecting system. Further, it is unnecessary
that the first detecting system is constructed to be adapted to the
liquid immersion. It is possible to use any conventional detecting
system as it is. When the reference on the substrate stage is
detected by using the second detecting system, the detection is
performed via the projection optical system and the liquid while
filling the space on the image plane side of the projection optical
system with the liquid in the same manner as in the liquid
immersion exposure. Accordingly, it is possible to accurately
detect the projection position of the image of the pattern on the
basis of the detection result. The baseline amount, which is the
positional relationship (distance) between the detection reference
position of the first detecting system and the projection position
of the image of the pattern, can be accurately determined on the
basis of the respective pieces of position information about the
substrate stage during the detecting operations of the first and
second detecting systems. The substrate (shot area) and the image
of the pattern of the mask can be accurately subjected to the
positional adjustment on the basis of the baseline amount even when
the overlay exposure is performed for the substrate.
[0032] According to an eleventh aspect of the present invention,
there is provided an exposure method for exposing a substrate by
projecting an image of a pattern onto the substrate through a
liquid; the exposure method comprising detecting an alignment mark
on the substrate held by a substrate stage provided with a
reference and a substrate holder, by using a first detector;
detecting the reference through the liquid by using a second
detector in a state in which the substrate or a dummy substrate is
arranged on the substrate holder; and performing positional
adjustment for the substrate and the image of the pattern on the
basis of detection results obtained by the first and second
detectors to expose the substrate with the image of the
pattern.
[0033] According to the exposure method of the eleventh aspect of
the present invention, the substrate or the dummy substrate is
arranged on the substrate holder when the reference provided on the
substrate stage is detected by the second detector through the
liquid. Therefore, it is possible to effectively avoid the inflow
of the liquid into the substrate stage.
[0034] According to a twelfth aspect of the present invention,
there is provided an exposure method for exposing a substrate by
projecting an image of a pattern through a liquid onto the
substrate held by a substrate holder of a movable substrate stage;
the exposure method comprising detecting whether or not the
substrate or a dummy substrate is held by the substrate holder; and
setting a movable area of the substrate stage depending on an
obtained detection result.
[0035] According to the exposure method of the twelfth aspect of
the present invention, the movable area of the substrate stage is
set, for example, such that the interior of the substrate stage is
prevented from any inflow of the liquid when it is detected that
the substrate or the dummy substrate is not held by the substrate
holder.
[0036] According to a thirteenth aspect of the present invention,
there is provided an exposure method for exposing a substrate by
projecting an image of a pattern through a liquid onto the
substrate held by a movable substrate stage; the exposure method
comprising detecting whether or not the substrate or a dummy
substrate is held by the substrate stage; and judging whether or
not a liquid immersion area is to be formed on the substrate stage
depending on an obtained detection result.
[0037] According to the exposure method of the thirteenth aspect of
the present invention, the supply of the liquid onto the substrate
stage is stopped, for example, when it is detected that the
substrate or the dummy substrate is not held by the substrate
stage. Therefore, it is possible to avoid the inflow of the liquid
into the substrate stage.
[0038] According to the present invention, there is provided a
method for producing a device, comprising using the exposure
apparatus as described above. According to the present invention,
there is provided a method for producing a device, comprising using
the exposure method as described above.
[0039] According to the present invention, the liquid immersion
exposure process can be performed in a state in which the accurate
positional adjustment is achieved for the substrate (shot area) and
the projection position of the image of the pattern. Therefore, it
is possible to produce the device which can exhibits the desired
performance. The device having the desired performance can be
produced by using the exposure apparatus which is capable of
suppressing the leakage and the inflow of the liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 shows a schematic arrangement illustrating an
embodiment of an exposure apparatus of the present invention.
[0041] FIG. 2 shows a schematic arrangement illustrating a liquid
supply mechanism liquid recovery mechanism.
[0042] FIG. 3 shows a schematic plan view illustrating the liquid
supply mechanism and the liquid recovery mechanism.
[0043] FIG. 4 shows a plan view illustrating a substrate stage.
[0044] FIGS. 5A and 5B show a reference member.
[0045] FIG. 6 shows a flow chart illustrating an embodiment of an
exposure method of the present invention.
[0046] FIG. 7 schematically shows another embodiment of a substrate
stage according to the present invention.
[0047] FIG. 8 schematically shows another embodiment of the
substrate stage according to the present invention.
[0048] FIG. 9 shows a plan view illustrating an embodiment of an
exposure apparatus provided with a waiting place for a dummy
substrate.
[0049] FIGS. 10A and 10B schematically show another embodiment of a
substrate stage according to the present invention.
[0050] FIGS. 11A and 11B illustrate the movement locus of the
substrate stage according to the present invention.
[0051] FIG. 12 illustrates the movement locus of the substrate
stage according to the present invention.
[0052] FIGS. 13A and 13B illustrate the operation of the liquid
supply mechanism according to the present invention.
[0053] FIG. 14 shows a flow chart illustrating exemplary steps of
producing a semiconductor device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
[0054] The exposure apparatus according to the present invention
will be explained below with reference to the drawings. However,
the present invention is not limited thereto.
[0055] FIG. 1 shows a schematic arrangement illustrating an
embodiment of an exposure apparatus of the present invention. With
reference to FIG. 1, the exposure apparatus EX includes a mask
stage MST which supports mask M, a substrate stage PST which
supports a substrate P, an illumination optical system IL which
illuminates, with an exposure light beam EL, the mask M supported
by the mask stage MST, a projection optical system PL which
performs the projection exposure for the substrate P supported by
the substrate stage PST with an image of a pattern of the mask M
illuminated with the exposure light beam EL, and a control unit
CONT which integrally controls the operation of the entire exposure
apparatus EX.
[0056] The exposure apparatus EX of this embodiment is a liquid
immersion exposure apparatus to which the liquid immersion method
is applied in order that the exposure wavelength is substantially
shortened to improve the resolution and the depth of focus is
substantially widened. The exposure apparatus EX includes a liquid
supply mechanism 10 which supplies the liquid LQ onto the substrate
P. And a liquid recovery mechanism 20 which recovers the liquid LQ
from the substrate P. In this embodiment, pure water is used for
the liquid LQ. The exposure apparatus EX forms a liquid immersion
area AR2 (locally) on at least a part of the substrate P including
a projection area AR1 of the projection optical system PL by the
liquid LQ supplied from liquid supply mechanism 10 at least during
the period in which the image of the pattern of the mask M is
transferred onto the substrate P. Specifically, the exposure
apparatus EX is operated as follows. That is, the space between the
surface (exposure surface) of the substrate P and the optical
element 2 disposed at the end portion of the projection optical
system PL is filled with the liquid LQ. The image of the pattern of
the mask M is projected onto the substrate P to expose the
substrate P therewith via the projection optical system PL and the
liquid LQ between the projection optical system PL and the
substrate P.
[0057] The embodiment of the present invention will be explained as
exemplified by a case using the scanning type exposure apparatus
(so-called scanning stepper) as the exposure apparatus EX in which
the substrate P is exposed with the pattern formed on the mask M
while synchronously moving the mask M and the substrate P in
mutually different directions (opposite directions) in the scanning
directions (predetermined directions). In the following
explanation, the X axis direction is the synchronous movement
direction (scanning direction, predetermined direction) for the
mask M and the substrate P in the horizontal plane, the Y axis
direction (non-scanning direction) is the direction which is
perpendicular to the X axis direction in the horizontal plane, and
the Z axis direction is the direction which is perpendicular to the
X axis direction and the Y axis direction and which is coincident
with the optical axis AX of the projection optical system PL. The
directions of rotation (inclination) about the X axis, the Y axis,
and the Z axis are designated as .theta.X, .theta.Y, and .theta.Z
directions respectively. The term "substrate" referred to herein
includes those obtained by coating a semiconductor wafer surface
with a resist, and the term "mask" includes a reticle formed with a
device pattern to be subjected to the reduction projection onto the
substrate.
[0058] The illumination optical system IL is used so that the mask
M, which is supported on the mask stage MST, is illuminated with
the exposure light beam EL. The illumination optical system IL
includes, for example, an exposure light source, an optical
integrator which uniformizes the illuminance of the light flux
radiated from the exposure light source, a condenser lens which
collects the exposure light beam EL emitted from the optical
integrator, a relay lens system, and a variable field diaphragm
which sets the illumination area on the mask M illuminated with the
exposure light beam EL to be slit-shaped. The predetermined
illumination area on the mask M is illuminated with the exposure
light beam EL having a uniform illuminance distribution by the
illumination optical system IL. Those usable as the exposure light
beam EL radiated from the illumination optical system IL include,
for example, emission lines (g-ray, h-ray, i-ray) in the
ultraviolet region radiated, for example, from a mercury lamp, far
ultraviolet light beams (DUV light beams) such as the KrF excimer
laser beam (wavelength: 248 nm), and vacuum ultraviolet light beams
(VUV light beams) such as the ArF excimer laser beam (wavelength:
193 nm) and the F.sub.2 laser beam (wavelength: 157 nm). In this
embodiment, the ArF excimer laser beam is used. As described above,
the liquid LQ is pure water in this embodiment, through which even
the ArF exposure light beam as the exposure light beam EL is
transmissive. Those also capable of being transmitted through pure
water include the emission line (g-ray, h-ray, i-ray) in the
ultraviolet region and the far ultraviolet light beam (DUV light
beam) such as the KrF excimer laser beam (wavelength: 248 nm).
[0059] The mask stage MST is movable while holding the mask M. The
mask stage MST is two-dimensionally movable in the plane
perpendicular to the optical axis AX of the projection optical
system PL, i.e., in the XY plane, and it is finely rotatable in the
.theta.Z direction. The mask stage MST is driven by a mask
stage-driving unit MSTD such as a linear motor. The mask
stage-driving unit MSTD is controlled by the control unit CONT. A
movement mirror 50, which is movable together with the mask stage
MST, is provided on the mask stage MST. A laser interferometer 51
is provided at a position opposed to the movement mirror 50. The
position in the two-dimensional direction and the angle of rotation
of the mask M on the mask stage MST are measured in real-time by
the laser interferometer 51. The result of the measurement is
outputted to the control unit CONT. The control unit CONT drives
the mask stage-driving unit MSTD on the basis of the result of the
measurement obtained by the laser interferometer 51 to thereby
position the mask M supported on the mask stage MST.
[0060] The projection optical system PL projects the pattern on the
mask M onto the substrate P at a predetermined projection
magnification .beta. to perform the exposure. The projection
optical system PL includes a plurality of optical elements
including an optical element (lens) 2 provided at the end portion
on the side of the substrate P. The optical elements are supported
by a barrel PK. In this embodiment, the projection optical system
PL is based on the reduction system having the projection
magnification .beta. which is, for example, 1/4 or 1/5. The
projection optical system PL may be any one of the 1.times.
magnification system and the magnifying system. The projection
optical system PL may be either a projection optical system of the
cata-dioptric type including catoptric and dioptric elements or a
projection optical system of the catoptric type including only a
catoptric element. The optical element 2, which is disposed at the
end portion of the projection optical system PL of this embodiment,
is provided detachably (exchangably) with respect to the barrel PK.
The optical element 2, which is disposed at the end portion, is
exposed from the barrel PK. The liquid LQ of the liquid immersion
area AR2 makes contact with the optical element 2. Accordingly, the
barrel PK, which is formed of metal, is prevented from any
corrosion or the like.
[0061] The optical element 2 is formed of fluorite. Fluorite has a
high affinity for water. Therefore, the liquid LQ is successfully
allowed to make tight contact with substantially the entire surface
of the liquid contact surface 2a of the optical element 2. That is,
in this embodiment, the liquid (water) LQ, which has the high
affinity for the liquid contact surface 2a of the optical element
2, is supplied. Therefore, the highly tight contact is effected
between the liquid LQ and the liquid contact surface 2a of the
optical element 2. The optical element 2 may be formed of quartz
having a high affinity for water. A water-attracting (lyophilic or
liquid-attracting) treatment may be performed to the liquid contact
surface 2a of the optical element 2 to further enhance the affinity
for the liquid LQ.
[0062] The exposure apparatus EX has a focus-detecting system 4.
The focus-detecting system 4 includes a light-emitting section 4a
and a light-receiving section 4b. A detecting light beam is
radiated in an oblique direction from the light-emitting section 4a
via the liquid LQ onto the surface (exposure surface) of the
substrate P. A reflected light beam thereof is received by the
light-receiving section 4b. The control unit CONT controls the
operation of the focus-detecting system 4. Further, the control
unit CONT detects the position (focus position) of the surface of
the substrate P in the Z axis direction with respect to a
predetermined reference plane on the basis of light-receiving
result of the light-receiving section 4b. When the focus positions
are determined at a plurality of points on the surface of the
substrate P respectively, the focus-detecting system 4 can also
determine the posture of the substrate P in the inclined direction.
A structure which is disclosed, for example, in Japanese Patent
Application Laid-open No. 8-37149, can be used for the
focus-detecting system 4. The focus-detecting system 4 may also be
of a type in which the detecting light beam is radiated onto the
surface of the substrate P not through the liquid.
[0063] The subs rate stage PST is movable while holding the
substrate P. The substrate stage PST includes a Z stage 52 which
holds the substrate P by the aid of a substrate holder PSH, and an
XY stage 53 which supports the Z stage 52. The XY stage 53 is
supported on a base 54. The substrate stage PST is driven by a
substrate stage-driving unit PSTD such as a linear motor. The
substrate stage-driving unit PSTD is controlled by the control unit
CONT. It goes without saying that the Z stage and the XY stage are
provided as an integrated body. The position of the substrate P in
the XY directions (position in the direction substantially in
parallel to the image plane of the projection optical system PL) is
controlled by driving the XY stage 53 of the substrate stage
PST.
[0064] A movement mirror 55, which is movable together with the
substrate stage PST with respect to the projection optical system
PL, is provided on the substrate stage PST (Z stage 52). A laser
interferometer 56 is provided at a position opposed to the movement
mirror 55. The angle of rotation and the position in the
two-dimensional direction of the substrate P on the substrate stage
PST are measured in real-time by the laser interferometer 56. The
result of the measurement is outputted to the control unit CONT.
The control unit CONT positions the substrate P supported by the
substrate stage PST in the X axis direction and the Y axis
direction by driving the XY stage 53 by the aid of the substrate
stage-driving unit PSTD in the two-dimensional coordinate system
defined by the laser interferometer 56.
[0065] The control unit CONT controls the position (focus position)
of the substrate P held by the Z stage 52 in the Z axis direction
and the position in the .theta.X and .theta.Y directions by driving
the Z stage 52 of the substrate stage PST by the aid of the
substrate stage-driving unit PSTD. That is, the Z stage 52 is
operated on the basis of the instruction from the control unit CONT
based on the detection result of the focus-detecting system 4. The
angle of inclination and the focus position (Z position) of the
substrate P are controlled so that the surface (exposure surface)
of the substrate P is adjusted to match the image plane to be
formed via the projection optical system PL and the liquid LQ,
[0066] An auxiliary plate 57 is provided on the substrate stage PST
(Z stage 52) so that the substrate P is surrounded thereby. The
auxiliary plate 57 has a flat surface which has approximately the
same height as that of the surface of the substrate P held by the
substrate holder PSH. In this arrangement, a gap of about 0.1 to 2
mm is provided between the auxiliary plate 57 and the edge of the
substrate P. However, the liquid LQ scarcely flows into the gap
owing to the surface tension of the liquid LQ. Even when any
portion in the vicinity of the circumferential edge of the
substrate P is subjected to the exposure, the liquid LQ can be
retained under the projection optical system PL by the aid of the
auxiliary plate 57. The substrate holder PSH may be provided as
another member separately from the substrate stage PST (Z stage
52). Alternatively, the substrate holder PSH may be provided
integrally with the substrate stage PST (Z stage 52).
[0067] A substrate alignment system 5, which detects alignment
marks 1 formed on the substrate P or a substrate side reference
mark PFM formed on a reference member 3 provided on the Z stage 52,
is provided in the vicinity of the end portion of the projection
optical system PL. A mask alignment system 6, which detects a mask
side reference mark MFM formed on the reference member 3 provided
on the Z stage 52 via the mask M and the projection optical system
PL, is provided in the vicinity of the mask stage MST. A structure,
which is disclosed, for example, in Japanese Patent Application
Laid-open No. 4-65603, can be used for the substrate alignment
system 5. A liquid-repellent cover (not shown) is provided to avoid
any adhesion of the liquid around the optical element disposed at
the terminal end of the substrate alignment system 5 (optical
element disposed most closely to the substrate P and the substrate
stage PST). The surface of the optical element disposed at the
terminal end of the substrate alignment system 5 is coated with a
liquid-repellent material. The adhesion of the liquid LQ is avoided
as well as an operator can easily wipe out the liquid even when the
liquid adheres to the optical element disposed at the terminal end.
A seal member such as a V-ring, which is provided in order to avoid
any inflow of the liquid, is arranged between the optical element
disposed at the terminal end of the substrate alignment system 5
and a metal fixture which holds the optical element. Those usable
for the arrangement of the mask alignment system 6 include, for
example, those disclosed in Japanese Patent Application Laid-open
Nos. 7-176468 and 58-7823.
[0068] The liquid supply mechanism 10 includes a liquid supply unit
11 which is capable of supplying the predetermined liquid LQ onto
the substrate P in order to form the liquid immersion area AR2 and
feeding the liquid LQ, and supply nozzles 13 which are connected to
the liquid supply unit 11 via a supply tube 12 and which have
supply ports for supplying the liquid LQ, fed from the liquid
supply unit 11, onto the substrate P. The supply nozzles 13 are
arranged closely to the surface of the substrate P.
[0069] The liquid supply unit 11 includes, for example, a tank for
accommodating the liquid LQ, and a pressurizing pump. The liquid
supply unit 11 supplies the liquid LQ onto the substrate P via the
supply tube 12 and the supply nozzles 13. The liquid supply
operation of the liquid supply unit 11 is controlled by the control
unit CONT. The control unit CONT is capable of controlling the
liquid supply amount per unit time to the surface of the substrate
P by the liquid supply unit 11. The liquid supply unit 11 further
includes a temperature-adjusting mechanism for the liquid LQ. The
liquid LQ, which has approximately the same temperature (for
example, 23.degree. C.) as the temperature in the chamber for
accommodating the apparatus therein, is supplied onto the substrate
P. It is not necessarily indispensable that the exposure apparatus
EX is provided with the tank and the pressurizing pump which are
used to supply the liquid LQ. It is also possible to utilize the
equipment of a factory or the like in which the exposure apparatus
EX is installed.
[0070] The liquid recovery mechanism 20 includes recovery nozzles
23 which recover the liquid LQ from the surface of the substrate P
and which are arranged closely to the surface of the substrate P,
and a liquid recovery unit 21 which is connected to the recovery
nozzles 23 via a recovery tube 22. The liquid recovery unit 21
includes, for example, a vacuum system (suction unit) such as a
vacuum pump, and a tank for accommodating the recovered liquid LQ.
The liquid recovery unit 21 recovers the liquid LQ from the surface
of the substrate P through the recovery nozzles 23 and the recovery
tube 22. The liquid recovery operation of the liquid recovery unit
21 is controlled by the control unit CONT. The control unit CONT is
capable of controlling the liquid recovery amount per unit time by
the liquid recovery unit 21. It is not necessarily indispensable
that the exposure apparatus EX is provided with the tank and the
vacuum system for recovering the liquid LQ. It is also possible to
utilize the equipment of a factory or the like in which the
exposure apparatus EX is installed.
[0071] FIG. 2 shows a front view illustrating those disposed in the
vicinity of the end portion of the projection optical system PL of
the exposure apparatus EX, the liquid supply mechanism 10, and the
liquid recovery mechanism 20. During the scanning exposure, an
image of a pattern of a part of the mask M is projected onto the
projection area AR1 disposed just under the optical element 2
disposed at the end portion of the projection optical system PL.
The mask M is moved at the velocity V in the -X direction (or in
the direction) with respect to the projection optical system PL, in
synchronization with which the substrate P is moved at the velocity
.beta.V (.beta. is the projection magnification) in the +X
direction (or in the -X direction) via the XY stage 53. After the
completion of the exposure for one shot area, the next shot area is
moved to the scanning start position in accordance with the
stepping of the substrate P. The exposure process is successively
performed thereafter for each of the shot areas in the
step-and-scan manner. This embodiment is designed so that the
liquid LQ is flowed along with the movement direction of the
substrate P.
[0072] FIG. 3 shows the positional relationship among the
projection area AR1 of the projection optical system PL, the supply
nozzles 13 (13A to 13C) for supplying the liquid LQ in the X axis
direction, and the recovery nozzles 23 (23A, 23B) for recovering
the liquid LQ. In FIG. 3, the projection area AR1 of the projection
optical system PL has a rectangular shape which is long in the Y
axis direction. The three supply nozzles 13A to 13C are arranged on
the side in the +X direction, and the two recovery nozzles 23A, 23B
are arranged on the side in the -X direction so that the projection
area AR1 is interposed thereby in the X axis direction. The supply
nozzles 13A to 13C are connected to the liquid supply unit 11 via
the supply tube 12, and recovery nozzles 23A, 23B are connected to
the liquid recovery unit 21 via the recovery tube 22. Further, the
supply nozzles 15A to 15C and the recovery nozzles 25A, 25B are
arranged in such a positional relationship that the positions of
the supply nozzles 13A to 13C and the recovery nozzles 23A, 23B are
rotated by substantially 180.degree.. The supply nozzles 13A to 13C
and the recovery nozzles 25A, 25B are alternately arranged in the Y
axis direction. The supply nozzles 15A to 15C and the recovery
nozzles 23A, 23B are alternately arranged in the Y axis direction.
The supply nozzles 15A to 15C are connected to the liquid supply
unit 11 via the supply tube 16. The recovery nozzles 25A, 25B are
connected to the liquid recovery unit 21 via the recovery tube
26.
[0073] When the scanning exposure is performed by moving the
substrate P in the scanning direction (-X direction) indicated by
the arrow Xa, the liquid LQ is supplied and recovered with the
liquid supply unit 11 and the liquid recovery unit 21 by using the
supply tube 12, the supply nozzles 13A to 13C, the recovery tube
22, and the recovery nozzles 23A, 23B. That is, when the substrate
P is moved in the -X direction, then the liquid LQ is supplied onto
the substrate P from the liquid supply unit 11 through the supply
tube 12 and the supply nozzles 13 (13A to 13C), and the liquid LQ
is recovered to the liquid recovery unit 21 through the recovery
nozzles 23 (23A, 23B) and the recovery tube 22. The liquid LQ flows
in the -X direction so that the space between the projection
optical system PL and the substrate P is filled therewith. On the
other hand, when the scanning exposure is performed by moving the
substrate P in the scanning direction (+X direction) indicated by
the arrow Xb, then the liquid LQ is supplied and recovered with the
liquid supply unit 11 and the liquid recovery unit 21 by using the
supply tube 16, the supply nozzles 15A to 15C, the recovery tube
26, and the recovery nozzles 25A, 25B. That is, when the substrate
P moved in the +X direction, then the liquid LQ is supplied from
the liquid supply unit 11 onto the substrate P through the supply
tube 16 and the supply nozzles 15 (15A to 15C), and the liquid LQ
is recovered to the liquid recovery unit 21 through the recovery
nozzles 25 (25A, 25B) and the recovery tube 26. The liquid LQ flows
in the direction so that the space between the projection optical
system PL and the substrate P is filled therewith. As described
above, the control unit CONT makes the liquid LQ to flow in the
same direction as the movement direction of the substrate P in
accordance with the movement direction of the substrate P by using
the liquid supply unit 11 and the liquid recovery unit 21. In this
arrangement, for example, the liquid LQ, which is supplied from the
liquid supply unit 11 via the supply nozzles 13, flows so that the
liquid LQ is attracted and introduced into the space between the
projection optical system PL and the substrate P in accordance with
the movement of the substrate P in the -X direction. Therefore,
even when the supply energy of the liquid supply unit 11 is small,
the liquid LQ can be supplied to the space between the projection
optical system PL and the substrate P with ease. By switching the
direction, in which the liquid LQ is made to flow, depending on the
scanning direction, it is possible to fill the space between the
substrate P and the projection optical system PL with the liquid
LQ, and it is possible to obtain the high resolution and the wide
depth of focus, even when the substrate P is subjected to the
scanning in any one of the +X direction and the -X direction.
[0074] FIG. 4 shows a schematic plan view illustrating the Z stage
52 of the substrate stage PST as viewed from an upper position. The
movement mirrors 55 are arranged on the two side surfaces of the
rectangular Z stage 52, the two side surfaces being perpendicular
to each other. The substrate P is held at a substantially central
portion of the Z stage 52 by the aid of the unillustrated substrate
holder PSH. As described above, the auxiliary plate 57, which has
the flat surface having approximately the same height as that of
the surface of the substrate P, is provided around the substrate P.
The plurality of shot areas S1 to S20 as the exposure objective
areas are set in a matrix form on the substrate P. The alignment
marks 1 are formed in attendance on the respective shot areas S1 to
S20 respectively. The respective shot areas are depicted in FIG. 4
such that the respective shot areas are adjacent to one another.
However, the respective shot areas are actually separated or away
from each other. The alignment marks 1 are provided on scribe lines
which are separation areas thereof.
[0075] The reference member 3 is provided at one corner of the Z
stage 52. The reference member PFM to be detected by the substrate
alignment system 5 and the reference member MFM to be detected by
the mask alignment system 6 are arranged separately in a
predetermined positional relationship on the reference member 3. An
optical member such as a glass plate member is used for the base
material for the reference member 3. The patterning is performed,
for example, with mutually different materials (materials having
different light reflectances) on the base material, and thus the
reference marks PFM, MFM are formed. The reference marks PFM, MFM
are formed so that they are free from any difference in level. The
surface of the reference member 3 is substantially flat. Therefore,
the surface of the reference member 3 can also serve as the
reference surface for the focus-detecting system 4.
[0076] FIG. 5 shows the reference member 3, wherein FIG. 5A shows a
plan view, and FIG. 5B shows a sectional view taken along the arrow
A-A shown in FIG. 5A. The reference member 3 has a base member 33
which is formed of a glass plate member or the like, and a first
material 31 and a second material 32 which are subjected to the
patterning on the base member 33 and which have mutually different
light reflectances. In this embodiment, the first material 31 is
composed of chromium oxide (Cr.sub.2O.sub.3) having the low light
reflectance, and the second material 32 is composed of chromium
(Cr) having the light reflectance higher than that of the chromium
oxide. The reference marks PFM, MFM, each of which is formed to be
cross-shaped, are formed of chromium oxide. Chromium is arranged to
surround the circumferences of the reference marks PFM, MFM.
Further, chromium oxide is arranged in outer areas of the chromium.
As for the materials to be used, there is no limitation to the
combination of the materials as described above. For example, the
first material may be composed of aluminum, and the second material
may be composed of chromium. The reference marks PFM, MFM are level
difference-free marks which are formed such that the upper surfaces
of the reference marks PFM, MFM are free from any difference in
level.
[0077] In order to form the level difference-free mark as described
above, for example, a chromium oxide film is provided on the base
member 33 by means of, for example, the vapor deposition, and then
grooves are formed in a predetermined area of the chromium oxide
film by means of, for example, the etching process. Chromium is
provided in grooves, and then the upper surface is subjected to the
polishing process, for example, by means of the CMP process
(chemical and mechanical polishing treatment). Accordingly, it is
possible to form the level difference-free mark composed of
chromium oxide and chromium. The level difference-free mark can be
also formed such that grooves are formed on the base member 33,
chromium or chromium oxide is embedded in the grooves, and then the
polishing process performed. Alternatively, the level
difference-free mark can be also formed such that a material such
as a photosensitive material, which is denatured or altered by the
optical treatment (or the heat treatment), is coated on the base
member 33, and the light (or the heat) is applied to an area
corresponding to the reference mark to be formed so that the area
is denatured (for example, discolored). Further alternatively, the
upper surface of the reference member 3 can be also made free from
any difference in level (flat) such that a mark is formed by means
of, for example, the vapor deposition of a chromium film on the
base member 33, and the surface thereof is subjected to the coating
with a light-transmissive material such as quartz.
[0078] At least a part of the area of the upper surface of the
reference member 3, which includes the reference marks PFM, MFM, is
liquid-repellent (water-repellent). In this embodiment, the entire
region of the upper surface of the reference member 3 is
liquid-repellent. In this embodiment, the upper surface of the
reference member 3 is liquid-repellent by performing the
liquid-repelling treatment to apply the liquid repellence. The
liquid-repelling treatment includes, for example, a coating
treatment using a material having the liquid repellence. The
material having the liquid repellence includes, for example,
fluorine-based compounds, silicon compounds, and synthetic resins
such as acrylic resins and polyethylene. The thin film, which is
adopted for the surface treatment, may be either a single layer
film or a film formed of a plurality of layers.
[0079] The upper surface of the reference member 3 may be also made
liquid-repellent by using materials having liquid repellence as the
first and second materials 31, 32 for forming the reference marks
PFM, MFM. The reference member having the flat upper surface (free
from any difference in level) can be also formed by forming the
reference mark with a predetermined material such as chromium on a
first glass plate member, overlapping a second glass plate member
thereon, and interposing the reference mark composed of chromium or
the like between the first and second glass plate members. In this
procedure, it is enough that the liquid-repelling treatment is
performed to the second glass plate member. Therefore, it is
possible to smoothly perform the liquid-repelling treatment.
[0080] In this embodiment, the reference marks PFM, MFM are formed
to be cross-shaped. However, their shapes are not limited to the
cross-shaped configurations. It is possible to use any mark shape
most appropriate for each of the detecting systems. The reference
marks PFM, MFM are illustrated while being emphasized. However,
each of the reference marks PFM, MFM actually has a line width of
about several .mu.m. When a system as disclosed in Japanese Patent
Application Laid-open No. 58-7823 is used as the mask alignment
system 6, a light-transmitting portion is formed as the reference
member MFM for the reference member 3. Also in this case, it is
desirable that the upper surface of the reference member 3 is made
to be free from any difference in level either by embedding a
light-transmissive material such as quartz in the
light-transmitting portion of the reference member 3 or by coating
the upper surface of the reference member 3 with a
light-transmissive material. As described above, the upper surface
of the reference member 3 is used as the reference surface for the
focus-detecting system 4. However, a reference surface of the
focus-detecting system 4 may be provided on the Z stage 52
separately from the reference member 3. Further, the reference
member 3 and the auxiliary plate 57 may be provided as an
integrated body.
[0081] Next, an explanation will be made with reference to a flow
chart shown in FIG. 6 about an example of the procedure for
exposing the substrate P with the pattern of the mask M by using
the exposure apparatus EX described above.
[0082] The substrate P is loaded on the substrate holder. PSH of
the Z stage 52, and the substrate holder PSH is made to hold the
substrate P (see FIG. 1). The measurement process is firstly
performed in a state in which the liquid LQ is absent on the
substrate P before supplying the liquid LQ from the liquid supply
mechanism 10. The control unit CONT moves the XY stage 53 while
monitoring the output of the laser interferometer 56 so that the
optical axis AX of the projection optical system PL is advanced
along the broken line arrow C shown in FIG. 4. During the movement,
the substrate alignment system 5 successively detects the plurality
of alignment marks 1 formed on the substrate P accompanied with the
shot areas S1 to S20 not through the liquid LQ (Step SA1).
[0083] When the substrate alignment system 5 detects the alignment
mark, the XY stage 53 is stopped. The position of the substrate
stage PST, which is provided when the substrate alignment system 5
detects the alignment mark 1, is measured by the laser
interferometer 56. As a result, the information about each of the
alignment marks 1 in the coordinate system defined by the laser
interferometer 56 is measured. The detection result of the position
information about the alignment mark 1, which is detected by using
the substrate alignment system 5 and the laser interferometer 56,
is outputted to the control unit CONT. The FIA (Field Image
Alignment) system is adopted for the substrate alignment system 5
of this embodiment, in which the illumination light beam such as
the white light emitted from a halogen lamp is radiated onto the
mark while allowing the substrate stage PST to stand still to
photograph the obtained image of the mark in a predetermined image
pickup field by an image pickup element, and the position of the
mark is measured by means of the image processing.
[0084] The substrate alignment system 5 has the detection reference
position in the coordinate system defined by the laser
interferometer 56. The position information about the alignment
mark 1 is detected as a deviation with respect to the detection
reference position.
[0085] In this embodiment, the position information about the shot
areas S1 to S20 is determined in accordance with the so-called EGA
(Enhanced Global Alignment) system as disclosed, example, in
Japanese Patent Application Laid-open No. 61-44429. Therefore, the
control unit CONT designates at least three areas (EGA shot areas)
of the plurality of shot areas S1 to S20 formed on the substrate P.
The alignment marks 1 accompanied with the respective shot areas
are detected by using the substrate alignment system 5. The
substrate alignment system 5 may detect all of the alignment marks
1 on the substrate P.
[0086] The information about the surface of the substrate P is
detected by the focus-detecting system 4 not through the liquid LQ
during the movement of the XY stage 53. The focus-detecting system
4 detects the deviation between the surface of the substrate P and
the image formation plane of the image of the pattern formed via
the projection optical system PL and the liquid LQ. The surface
information is detected by the focus-detecting system 4 for each of
all of the shot areas S1 to S20 on the substrate P. The detection
result is stored in the control unit CONT while corresponding to
the position of the substrate P in the scanning direction (X axis
direction). The surface information may be detected by the
focus-detecting system for only a part of the shot areas.
[0087] Subsequent the control unit CONT determines the position
information of each of the plurality of shot areas S1 to S20 on the
substrate P by means of the calculation process (EGA process) on
the basis of the detection results of the position information of
the alignment marks 1 (Step SA2).
[0088] In the EGA system, the position information (coordinate
position) of the alignment mark 1 accompanied with the EGA shot
area designated in Step SA1 is detected by using the substrate
alignment system 5, and then the error parameter (offset, scale,
rotation, degree of perpendicularity) concerning the arrangement
characteristic (position information) of the shot areas S1 to S20
on the substrate P is determined by performing the statistical
calculation based on, for example, the least square method on the
basis of the detected value and the designed value. The designed
coordinate values are corrected for all of the shot areas S1 to S20
on the substrate P on the basis of the determined value of the
parameter. Accordingly, the positional relationship is determined
between the detection reference position of the substrate alignment
system 5 and each of the shot areas on the substrate P placed on
the substrate stage PST. That is, the control unit CONT can know,
from the output of the laser interferometer 56, the position at
which each of the shot areas on the substrate P is located with
respect to the detection reference position of the substrate
alignment system 5.
[0089] When the detection of the alignment mark 1 of the substrate
P and the detection of the surface information of the substrate P
are completed, the control unit CONT moves the XY stage 53 so that
the detection area of the substrate alignment system 5 is
positioned on the reference member 3. The substrate alignment
system 5 detects the reference mark PFM on the reference member 3
in the absence of any liquid to detect the position information of
the reference mark PFM in the coordinate system defined by the
laser interferometer 56 (Step SA3).
[0090] The detection of the position information about the
reference mark PFM by using the substrate alignment system 5
results in the detection of the positional relationship between the
reference mark PFM and the detection reference position of the
substrate alignment system 5 in the coordinate system defined by
the laser interferometer 56.
[0091] After the completion of both of the detection of the
position information about the alignment mark 1 using the substrate
alignment system 5 and the detection of the position information
about the reference mark PFM on the Z stage 52, the control unit
CONT moves the XY stage 53 so that the reference mark MFM on the
reference member 3 can be detected by the mask alignment system 6.
The mask alignment system 6 observes the reference mark MFM via the
projection optical system PL. Therefore, the end portion of the
projection optical system PL is opposed to the reference member 3.
In this situation, the control unit CONT starts the supply and the
recovery of the liquid LQ by the liquid supply mechanism 10 and the
liquid recovery mechanism 20. The space between the upper surface
of the reference member 3 and the end surface of the optical
element 2 disposed at the end portion of the projection optical
system PL is filled with the liquid LQ to form the liquid immersion
area. It is desirable that the liquid immersion area AR2 is formed
on only the reference member 3. However, the liquid immersion area
AR2 may be formed to range over the reference member 3 and the
auxiliary plate 57. Alternatively, the liquid immersion area AR2
may be formed to range over the reference member 3, the auxiliary
plate 57, and the substrate P.
[0092] Subsequently, the control unit CONT detects the reference
member MFM via the mask M, the projection optical system PL, and
the liquid LQ by the mask alignment system 6 (Step SA4).
[0093] Accordingly, the information about the projection position
of the image of the pattern of the mask M on the XY plane is
detected by using the reference mark. MFM via the projection
optical system PL and the liquid LQ. The positional relationship
between the reference mark MFM and the projection position of the
image of the pattern in the coordinate system defined by the laser
interferometer 56 is measured. The mask alignment system 6 of this
embodiment adopts the VRA (Visual Reticle Alignment) system in
which the light beam is radiated onto the mark, and the image data
of the mark obtained the image pickup with a CCD camera or the like
is subjected to the image processing to detect the mark
position.
[0094] The control unit CONT determines a baseline amount which is
the spacing distance (positional relationship) between the
detection reference position of the substrate alignment system 5
and the projection position of the image of the pattern (Step
SA5).
[0095] Specifically, the positional relationship (baseline amount)
between the detection reference position of the substrate alignment
system 5 and the projection position of the image of the pattern in
the coordinate system defined by the laser interferometer 5 is
determined from the positional relationship between the reference
mark PFM and the detection reference position of the substrate
alignment system 5 determined in Step SA3, the positional
relationship between the reference mark MFM and the projection
position of the image of the pattern determined in Step SA4, and
the predetermined positional relationship between the reference
mark MFM (reference member 3b) and the reference mark PFM
(reference member 3a).
[0096] When the measurement process is completed as described
above, the control unit CONT stops the supply operation of the
liquid LQ onto the reference member 3 having been performed by the
liquid supply mechanism 10. On the other hand, the control unit
CONT continues the recovery operation of the liquid LQ from the
surface of the reference member 3 by the liquid recovery mechanism
20 for a predetermined period of time. After the elapse of the
predetermined period of time, the control unit CONT stops the
recovery operation having been performed by the liquid recovery
mechanism 20. Accordingly, the liquid LQ is recovered from the
surface of the reference member 3. It is preferable to adopt such
an arrangement that the reference member 3 and the auxiliary plate
57 are provided as an integrated body, and the reference member 3b
and the substrate P are continued at approximately the same height
with the auxiliary plate 57 intervening therebetween. In this
arrangement, the liquid immersion area of the liquid LQ can be
moved from the reference member 3 to the substrate P in a state in
which the liquid LQ is retained on the image plane side of the
projection optical system PL without stopping the liquid supply
operation performed by the liquid supply mechanism 10.
[0097] Subsequently, the control unit CONT drives the liquid supply
mechanism 10 and the liquid recovery mechanism 20 in a state in
which the projection optical system PL and the substrate P are
opposed to each other to start the operation for supplying the
liquid onto the substrate P and the operation for recovering the
liquid from the surface of the substrate P. Accordingly, the liquid
immersion area AR2 is formed between the projection optical system
PL and the substrate P. After the liquid immersion area AR2 is
formed on the substrate P, the plurality of shot areas on the
substrate P are subjected to the liquid immersion exposure
respectively by successively projecting the image of the pattern
(Step SA6).
[0098] More specifically, the XY stage 53 is moved on the basis of
the position information about the respective shot areas with
respect to the detection reference position of the substrate
alignment system 5 determined in Step SA2 and the positional
relationship (baseline amount) between the detection reference
position of the substrate alignment system 5 and the projection
position of the image of the pattern determined in Step SA5. The
respective shot areas are subjected to the liquid immersion
exposure process while performing the positional adjustment between
the image of the pattern and the respective shot areas S1 to S20 on
the substrate P.
[0099] When the scanning exposure is performed for each of the shot
areas S1 to S20 on the substrate P, the exposure process is
performed by using the respective pieces of information determined
during the measurement process as described above. That is, the
respective shot areas are successively exposed while effecting the
positional adjustment to the projection position of the image of
the pattern on the basis of the arrangement (position information)
of the shot areas determined in Step SA2. It is also allowable to
use the so-called die-by-die system in which the alignment mark 1
in each of the shot areas on the substrate P is successively
detected by the substrate alignment system 5 to perform the overlay
exposure for the shot area. However, in this case, the liquid LQ is
disposed on the substrate P during the exposure for the shot area
on the substrate P, while the liquid LQ is not disposed on the
substrate P during the detection of the alignment mark 1 by the
substrate alignment system 5, and this operation is repeatedly
performed. Therefore, it is preferable to adopt such a procedure
that the arrangement (position information) of the shot areas is
previously determined, and the substrate P is successively moved in
accordance with the determined arrangement as in this
embodiment.
[0100] During the scanning exposure for each of the shot areas S1
to S20, the positional relationship between the surface of the
substrate P and the image plane formed through the liquid LQ is
adjusted without using the focus-detecting system 4 on the basis of
the surface information of the substrate P determined before the
supply of the liquid LQ. The positional relationship between the
image plane and the surface of the substrate P may be detected
through the liquid LQ during the scanning exposure to perform the
adjustment without determining the surface information of the
substrate P before the supply of the liquid LQ. Alternatively, the
both operations may be performed.
[0101] When the scanning exposure is completed for the respective
shot areas S1 to S20 on the substrate P, the control unit CONT
stops the liquid supply having been performed by the liquid supply
mechanism 10. On the other hand, the control unit CONT continues
the driving of the liquid recovery mechanism 20 for a predetermined
period of time after the stop of the liquid supply by the liquid
supply mechanism 10. Accordingly, the liquid LQ is recovered from
the surface of the substrate P. When the liquid LQ is recovered
from the surface of the substrate P, the liquid LQ may be recovered
while relatively moving the substrate P and the recovery nozzles 23
of the liquid recovery mechanism 20 by driving the substrate stage
PST.
[0102] When another substrate P' is held on the substrate stage PST
to perform the exposure after the completion of the exposure of the
substrate P, the shot area of the substrate P' and the projection
position of the image of the pattern of the mask can be subjected
to the positional adjustment without detecting the position
information about the reference marks PFM, MFM on the substrate
stage PST. In this procedure, the another substrate P' is held by
the substrate holder PSH on the Z stage 52, and then the position
information about the alignment mark 1 provided in attendance on
the shot area is detected by using the substrate alignment system
5. Accordingly, the position information about each of the shot
areas with respect to the detection reference position of the
substrate alignment system 5 is determined by using the EGA process
in the same manner as for the substrate P previously subjected to
the exposure. Accordingly, the projection optical system PL can be
opposed to the substrate P', each of the shot areas on the
substrate P' and the image of the pattern can be subjected to the
positional adjustment, and each of the shot areas on the substrate
P' can be exposed with the image of the pattern.
[0103] When the plurality of substrate P (P') are successively
exposed as described above, it is unnecessary that the operation
for detecting the reference mark PFM, MFM to determine the baseline
amount is performed every time when another substrate P' is held on
the Z stage 52 (substrate holder PSH). The position information
about the alignment mark 1 on the substrate P' held (loaded) on the
Z stage 52 is detected, and the substrate P' is moved on the basis
of the previously determined baseline amount. Accordingly, the
substrate P' and the image of the pattern can be subjected to the
positional adjustment efficiently and highly accurately. It is
enough that the operation for detecting the reference mark PFM, MFM
to determine the baseline amount is performed at every
predetermined period of time, for example, every time when a preset
number of the substrates are processed or every time when the mask
is exchanged.
[0104] As described above, when the reference mark PFM on the Z
stage 52 is detected by the substrate alignment system 5, the
detection is performed not through the liquid LQ. Accordingly, the
reference mark PFM can be satisfactorily detected without being
affected, for example, by the temperature change of the liquid LQ.
It is unnecessary that the substrate alignment system 5 is
constructed so that the substrate alignment system 5 is adapted to
the liquid immersion. It is possible to utilize any conventional
detecting system as it is. When the reference mark MFM on the Z
stage 52 is detected by using the mask alignment system 6, the
detection is performed via the projection optical system PL and the
liquid LQ while filling the space disposed on the image plane side
of the projection optical system PL with the liquid LQ, in the same
manner as in the liquid immersion exposure. Accordingly, it is
possible to accurately detect the projection position of the image
of the pattern on the basis of the detection result. The baseline
amount, which is the positional relationship (distance) between the
detection reference position of the substrate alignment system 5
and the projection position of the image of the pattern, can be
accurately determined on the basis of the respective pieces of the
position information about the substrate stage PST during the
detection operations of the substrate alignment system 5 and the
mask alignment system 6. The substrate P (shot areas S1 to S20) and
the image of the pattern of the mask M can be accurately subjected
to the positional adjustment on the basis of the baseline amount
even when the overlay exposure is performed for the substrate
P.
[0105] In this embodiment, the mark detection is performed by the
mask alignment system 6 in the state in which the liquid LQ is
disposed on the reference mark MFM (reference member 3). However,
the substrate P is arranged on the substrate holder PSH of the Z
stage 32 during the detection operation. Accordingly, even if the
liquid LQ flows out from the surface of the reference member 3, it
is possible to avoid the inflow of the liquid LQ into the substrate
holder PSH and into the substrate stage PST. Even when the liquid
immersion area AR2 protrudes from the inner edge of the auxiliary
plate 57, it is possible to avoid the inflow of the liquid LQ into
the substrate holder PSH and into the substrate stage PST.
Therefore, it is possible to avoid the occurrence of any
inconvenience including, for example, the trouble and/or the
electric leakage of the electric equipment in the substrate stage
PST and/or the rust on the respective members in the substrate
stage PST which would be otherwise caused by the inflowed liquid
LQ.
[0106] As described above, in this embodiment, the switching is
effected between a wet state in which the liquid LQ is disposed on
the reference member 3 and a dry state in which the liquid LQ not
disposed on the reference member 3 when the reference marks PFM,
MFM on the reference member 3 are detected. However, as explained
with reference to FIG. 5, the reference marks PFM, MFM, which are
formed on the reference member 3, are free from any difference in
level. Therefore, for example, even when the switching is effected
from the dry, state to the wet state, any bubble is hardly
generated at the mark portion in the liquid LQ on the reference
member 3. Even when the liquid LQ is recovered from the surface of
the reference member 3 in order to effect the switching from the
wet state to the dry state, then the liquid LQ can be recovered
satisfactorily, and no liquid LQ remains at the mark portion. In
particular, the liquid LQ can be recovered more satisfactorily,
because e upper surface of the reference member 3 is
liquid-repellent in this embodiment Therefore, for example, the
mask alignment system 6 can accurately perform the detection of the
reference mark MFM without being affected by the bubble or the
like. The substrate alignment system 5 can accurately perform the
detection of the reference mark PFM without being affected by any
remaining liquid LQ.
[0107] In this embodiment, the liquid LQ is not disposed on the
reference member 3 when the reference mark PFM is detected by the
substrate alignment system 5, and the liquid LQ is disposed on the
reference member 3 when the reference mark MFM is detected by the
mask alignment system 6. In this arrangement, the mask side
reference mark MFM and the substrate side reference mark PFM are
detected separately (not simultaneously). However, when the
reference mark PFM and the reference mark MFM are sufficiently
separated from each other on the reference member 3, and the
portion of the reference mark PFM is not exposed to the liquid LQ,
then the reference mark PFM may not be the level difference-free
mark. Further, the mask side reference mark MFM and the substrate
side reference mark PFM may be formed on different or distinct
reference members. In this case, when the mask side reference mark
MFM and the substrate side reference mark PFM are not detected
simultaneously as in this embodiment, it is unnecessary to form the
liquid immersion area on the reference member on which the
reference mark PFM is formed. Therefore, it is unnecessary to make
the adaptation to the liquid immersion, including, for example, the
arrangement in which the reference mark PFM is free from any
difference in level. Further, it is possible to avoid the
occurrence of any water mark or the like as well.
[0108] This embodiment is constructed as follows. That is, the
position information is firstly determined for the plurality of
shot areas S1 to S20 on the substrate P by detecting the alignment
marks 1 on the substrate P by the substrate alignment system 5 not
through the liquid LQ (Steps SA1, SA2). Subsequently, the reference
mark PFM on the substrate stage PST is detected not through the
liquid LQ (Step SA3). Subsequently, the space on the image plane
side of the projection optical system PL is filled with the liquid
LQ, and the reference mark MFM is detected by the mask alignment
system 6 via the projection optical system PL and the liquid LQ to
thereby determine the projection position of the image of the
pattern (Step SA4). The baseline amount, which is the positional
relationship (distance) between the detection reference position of
the substrate alignment system 5 and the projection position of the
image of the pattern, is accurately determined (Step SA5). After
that, the substrate P is subjected to the liquid immersion exposure
(Step SA6). That is, in this procedure, the space on the image
plane side of the projection optical system PL is not filled with
the liquid LQ in Steps SA1 to SA3 described above, and the space on
the image plane side of the projection optical system PL is filled
with the liquid LQ in Steps SA4 to SA6 described above.
Accordingly, it is possible to decrease the number of switching
operations for switching the dry state in which the space on the
image plane side of the projection optical system PL is not filled
with the liquid LQ and the wet state in which the space on the
image plane side of the projection optical system FL is filled with
the liquid LQ, thereby improving the throughput. For example, when
the wet state is switched to the dry state, it is necessary to
perform the operation for removing the liquid LQ remaining,
example, on the upper surface of the reference member 3 after the
switching. However, if the number of the switching operations is
increased, then the number of the operations for removing the
liquid is increased as well, and the process efficiency is lowered.
However, when the number of the switching operations is reduced, it
is possible to prove the throughput.
[0109] The reference mark PFM is detected by the substrate
alignment system S (Step SA3), and then the alignment marks 1 on
the substrate P are detected (Steps SA1, SA2). Subsequently, the
reference mark MFM is detected by the mask alignment system 6 via
the projection optical system PL and the liquid LQ (Steps SA4,
SA5), and then the substrate P is subjected to the liquid immersion
exposure process (Step SA6). Also in this way, it is possible to
decrease the number of the switching operations between the dry
state and the wet state in the same manner as in the embodiment of
the present invention. On the other hand, as in the embodiment of
the present invention, the operation for detecting the reference
mark PFM by the substrate alignment system 5 and the operation for
detecting the reference mark MFM by the mask alignment system 6 via
the projection optical system PL and the liquid LQ are performed
continuously. Therefore, it is possible to avoid the inconvenience
which would be otherwise caused such that the detection state,
which is brought about during the operation for detecting the
reference mark MFM by the mask alignment system 6, is greatly
varied from the detection state which is brought about during the
operation for detecting the reference mark PFM by the substrate
alignment system 5, and the baseline amount, which is the
positional relationship between the detection reference position of
the substrate alignment system 5 and the projection position of the
image of the pattern, cannot be measured accurately. For example,
there is a possibility of the occurrence of the physical
fluctuation of the positional relationship between the projection
optical system Pb and the alignment system 5, the fluctuation of
the optical characteristic of the alignment system 5, and the
fluctuation of the environment (temperature) on the measuring
optical path for the laser interferometer 56 to measure the
position of the substrate stage PST, for example, due to any
thermal fluctuation of the environment of the exposure apparatus
caused, for example, by the difference in heat generation amount
between the stopped state and the driving state of the linear motor
for driving the stage. In such a situation, if the temporal
interval is large between the timing of the operation for detecting
the reference mark PFM by the substrate alignment system 5 and the
timing of the operation for detecting the reference mark MFM by the
mask alignment system 6, there is such a possibility that the
inconvenience arises, in which the baseline amount cannot be
measured accurately due to the thermal fluctuation. However, when
the operation for detecting the reference mark PFM by the substrate
alignment system 5 and the operation for detecting the reference
mark MFM by the mask alignment system 6 are performed continuously
as in the embodiment of the present invention, it is possible to
avoid the inconvenience.
[0110] In the alignment sequence shown in the flow chart shown in
FIG. 6, the following procedure is adopted. That is, the alignment
marks 1 on the substrate P are detected not through the liquid
(Step SA1) to perform the EGA process (Step SA2), and then the
reference mark PFM is detected not through the liquid (Step SA3).
After that, the detection of the reference mark MFM is executed via
the projection optical system PL and the liquid (Step SA4).
However, the order of Step SA2 and Step SA3 may be exchanged. In
this case, the detection interval between the reference mark PFM
and the reference mark MFM is somewhat longer than that of the
sequence shown in FIG. 6. However, it is possible to perform a
small number of times of the operations of the liquid supply and
recovery in the same manner as in the sequence shown in FIG. 6.
Therefore, this procedure is advantageous in view of the
throughput. In the embodiment described above, the reference mark
PFM and the reference mark MFM are provided separately. However, it
is also allowable that one reference mark may be detected by the
substrate alignment system 5 and the mask alignment system 6.
Further, the detection of the reference mark PFM without any liquid
and the detection of the reference mark MFM through the liquid may
be executed to determine the baseline amount, and then the
alignment marks 1 on the substrate P may be detected.
[0111] FIGS. 7 and 8 schematically show another embodiment of the
present invention. FIG. 7 shows a state in which the projection
optical system PL is arranged over the substrate P, and FIG. 8
shows a state in which the projection optical system PL is arranged
over the reference member 3. With reference to gigs. 7 and 8, a
recess 60 is formed on the Z stage 52 in order to arrange the
substrate P on the substrate holder PSH, and a recess 61 is formed
on the Z stage 52 in order to arrange the reference member 3. The
upper surface of the substrate P arranged in the recess 60, the
upper surface of the reference member 3 arranged in the recess 61,
and the upper surface of the Z stage 52 are provided so that they
are substantially flush with one another. Accordingly, even when
the switching is effected from the state shown in FIG. 7 to the
state shown in FIG. 8 in order to detect the reference mark MFM on
the reference member 3 through the liquid LQ, the substrate stage
PST can be moved in the XY directions in a state in which the
liquid LQ is retained on the image plane side of the projection
optical system PL. Of course, even when the switching is effected
from the state shown in FIG. 8 to the state shown. FIG. 7, the
substrate stage PST can be moved in the XY directions in a state in
which the liquid LQ is retained on the image plane side of the
projection optical system PL. When the reference mark MFM on the
reference member 3 is detected through the liquid LQ, it is
considered that the following situation may arise depending on the
size of the liquid immersion area of the liquid LQ formed on the
reference member 3. That is, a part (end) of the liquid immersion
area on the reference member 3 may be arranged in the recess 60 in
which the substrate holder PSH is arranged, during the operation
for detecting the reference mark MFM. However, when the substrate P
is arranged in the substrate holder PSH of the recess 60, it is
possible to avoid the inflow of the liquid LQ into the recess 60.
The recess 60 can be made flat by arranging the substrate P. It is
possible to avoid any disturbance of the liquid immersion area
which would be otherwise caused by the recess (difference in level
or any stepped portion). In addition to the arrangement in which
the reference member 3 formed with the reference mark is embedded
in the recess 61 of the 21 stage 52, it is also allowable that the
reference mark is formed directly on the upper surface of the Z
stage 52 without providing the recess 61.
[0112] The embodiment described above adopts such a sequence that
the alignment marks 1 on the substrate P are detected, and then the
reference mark MFM is detected by the mask alignment system 6.
Therefore, the substrate P for producing the device is arranged on
the substrate holder PSH during the operation for detecting the
reference mark MFM by the mask alignment system 6 through the
liquid LQ. However, the following possibility arises. That is the
baseline amount may be measured singly in some cases. In other
cases, a sequence may be adopted, in which the substrate P is
loaded on the substrate holder PSH after the measurement of the
baseline amount. In such a situation, it is of course possible to
arrange a dummy substrate DP in the substrate holder PSH. In this
arrangement, the dummy substrate DP has approximately the same
shape and the same size as those of the substrate P for producing
the device. The dummy substrate DP may be formed of the same
material as that of the substrate P, for example, silicon. However,
various types of materials can be used for the dummy substrate DP
provided that there is no elution of pollution matters or the like
brought about by the contact with the liquid LQ, in this case, the
reference mark MFM is detected via the projection optical system PL
and the liquid LQ by the mask alignment system 6 in a state in
which the dummy substrate DP is arranged on the substrate holder
PSH. Subsequently, the reference mark. PFM is detected without any
liquid LQ by the substrate alignment system 5 to measure the
baseline amount. Before or after the operation of the detection by
the substrate alignment system 5, the dummy substrate DP is
unloaded from the substrate holder PSH, and the substrate P for
producing the device is loaded on the substrate holder PSH. The
alignment marks 1 on the substrate P are detected by the substrate
alignment system 5, and then the positional adjustment is performed
for the image of the pattern and the shot areas on the substrate P
on the basis of the baseline amount and the position information
about the alignment marks 1 on the substrate P to perform the
liquid immersion exposure.
[0113] FIG. 9 shows a plan view schematically illustrating an
example of an exposure apparatus EX provided with a dummy substrate
library 70A for storing the dummy substrate DP. With reference to
FIG. 9, the exposure apparatus EX is provided in a chamber
apparatus CH. The interior of the chamber apparatus CH is
maintained to be in a predetermined environment (temperature,
humidity) by an air conditioning system. The substrate stage PST is
provided movably in a predetermined movable range in the chamber
apparatus CH. A transport unit 80, which transports the substrate
P, is connected to the exposure apparatus EX. A coater/developer
C/D, which has a function to coat the substrate P with a
photosensitive material and a function to develop the substrate P
having been subjected to the exposure process, is connected via an
interface section IF to the transport unit 80. The transport unit
80 is provided with a first arm section 81 and a second arm section
82 for holding and transporting the substrate P. The first and
second arm sections 81, 82 are moved while being guided by guide
sections 81A, 82A respectively. The first and second arm sections
81, 82 and the guide sections 81A, 82A are provided in a second
chamber apparatus CH2. The substrate P before undergoing the
exposure process, which is coated with the photosensitive material
by the coater/developer C/D, is transported into the chamber
apparatus CH of the exposure apparatus EX by the first arm section
81 and the second arm section 82. When the substrate P before
undergoing the exposure process is loaded by the second arm section
82, the substrate stage PST is moved to the substrate exchange
position RP. The substrate stage PST, on which the substrate P has
been loaded at the substrate exchange position RP, is moved to the
exposure process position EP disposed under the projection optical
system PL. The substrate stage PST, which holds the substrate P
after the completion of the exposure process, is moved to the
substrate exchange position RP. The substrate P, for which the
exposure process has been completed, is unloaded by the second arm
section 82 (or another arm section) at the substrate exchange
position RP. The substrate P is transported by the first arm
section 81 (or another arm section) via the interface section IF to
the coater/developer C/D.
[0114] When the dummy substrate DP is arranged on the substrate
holder PSH, the control unit CONT takes out the dummy substrate DP
from the dummy substrate library 70A which is the waiting place for
the dummy substrate DP provided in the chamber apparatus CH, by
using, for example, the second arm section 82. The dummy substrate
DP is load on the substrate holder PSH of the substrate stage PST
at the substrate exchange position RP. The control unit CONT
detects the reference mark MFM, for example, via the projection
optical system PL and the liquid LQ by the mask alignment system 6
as described above, in state in which the dummy substrate DP is
held by the substrate holder PSH.
[0115] When the dummy substrate DP is unloaded from the substrate
stage PST after the completion of the detection process performed
through the liquid LQ as described above, the control unit CONT
firstly performs the operation for removing the liquid LQ adhering
and remaining on the dummy substrate DP, for example, by using the
liquid recovery mechanism 20. The substrate stage PST, which holds
the dummy substrate DP having been subjected to the liquid-removing
process, is moved by the control unit CONT to the substrate
exchange position RP. The control unit CONT unloads the dummy
substrate DP from the substrate stage PST by using the second arm
section 82 (or another arm section). The dummy substrate DP is
accommodated in the dummy substrate library 70A which is the
waiting place for the dummy substrate DP.
[0116] In this embodiment, the dummy substrate library 70A is
provided in the chamber apparatus CH for accommodating the exposure
apparatus EX. However, as indicated by the symbol 70B in FIG. 9,
the dummy substrate library may be provided, for example, in the
second chamber apparatus CH2 for accommodating the transport unit
80. Alternatively, the dummy substrate library may be arranged in
the coater/developer C/D.
[0117] It is preferable that the dummy substrate DP has the liquid
repellence. In this embodiment, the dummy substrate DP is subjected
to the liquid-repelling treatment to have the liquid repellence.
The liquid-repelling treatment includes, for example, a coating
treatment using a material having the liquid repellence. The
material having the liquid repellence includes, for example,
fluorine-based compounds, silicon compounds, and synthetic resins
such as acrylic resins and polyethylene. The thin film, which is
adopted for the surface treatment, may be either a single layer
film or a film formed of a plurality of layers.
[0118] The liquid repellence of the dummy substrate DP is
deteriorated in a time-dependent manner. Accordingly, the dummy
substrate DP may be exchanged depending on the deterioration of the
liquid repellence. Alternatively, the dummy substrate DP may be
formed of a liquid-repellent material (for example, fluorine-based
material or acrylic).
[0119] FIG. 10 schematically shows another embodiment. As shown in
FIG. 10, the following arrangement may also be adopted. That is, a
recess 60 is formed on the Z stage 52 (substrate stage PST). A
substrate holder PSH, which has a shape corresponding to the recess
60, is arranged in the recess 60, and a lifting unit 63, which
moves the substrate holder PSH upwardly and downwardly, is provided
in the Z stage 52. As shown in FIG. 10A, the lifting unit 63 moves
the substrate holder PSH upwardly so that the upper surface of the
Z stage 52 is flush with the upper surface of the substrate holder
PSH during the operation for detecting the reference mark MFM
through the liquid LQ by the mask alignment system 6. Accordingly,
it is also possible to avoid the occurrence of the inconvenience
which would be otherwise caused, for example, such that the liquid
LQ of the liquid immersion area, which is formed on the reference
member 3 in order to measure the reference mark MFM through the
liquid LQ, inflows into the Z stage (substrate stage PST). As shown
in FIG. 10B, the recess 60 is provided in order that the substrate
P is arranged by moving the substrate holder PSH downwardly by the
lifting unit 63, when the substrate P for producing the device is
held by the substrate holder PSH in order to perform the liquid
immersion exposure. When the liquid LQ is adhered to the surface of
the substrate holder PSH when the substrate P is placed, the
substrate P may be placed after removing or recovering the adhered
liquid LQ,
[0120] In the embodiment described above, the interior of the Z
stage 52 is prevented from any inflow of the liquid LQ by holding
the substrate P or the dummy substrate DP by the substrate holder
PSH when the reference mark MFM on the substrate stage PST is
detected via the projection optical system PL and the liquid LQ.
However, this prevention of the inflow is not limited to the time
of the detection of the reference mark MFM. It is desirable that
the inflow of the liquid LQ into the Z stage 52 (substrate stage
PST) is avoided by holding the substrate P or the dummy substrate
DP on the substrate holder PSH, or by using the arrangement as
shown in FIG. 10, when the liquid immersion area AR2 is formed at
the circumferential portion of the upper surface of the Z stage 52
(substrate stage PST), for example, when various types of measuring
sensors disposed on the Z stage 52 (substrate stage PST) are
used.
[0121] As described above, the operation for detecting the
reference marks PFM, MFM to determine the baseline amount may be
per formed at every predetermined period of time, for example,
every time when a preset number of the substrates are processed or
every time when the mask M is exchanged. In the embodiment
described above, the dummy substrate DP is held by the substrate
holder PSH, for example, when the baseline amount is measured
singly before the substrate P is loaded on the substrate holder
PSH. Accordingly, the interior of the substrate holder PSH and the
interior of the substrate stage PST are prevented from any inflow
of the liquid LQ. On the other hand, when the baseline amount is
measured, the operation for detecting the reference marks PFM, MFM
may be performed in order to determine the baseline amount in a
state in which the substrate P having been already subjected to the
exposure process is held on the substrate holder PSH, in place of
the state in which the dummy substrate DP is held on the substrate
holder PSH. Also in this way, the interior of the substrate holder
PSH and the interior of the substrate stage PST can be prevented
from any inflow of the liquid LQ. The substrate P having been
already subjected to the exposure process may be unloaded after the
completion of the measurement of the baseline amount. That is,
after the completion of the exposure for the substrate P, the
position information about the reference mark PFM on the substrate
stage PST is detected by the substrate alignment system 5, and the
position information about the reference mark MFM on the substrate
stage PST is detected by the mask alignment system 6 in the state
in which the substrate P having been already subjected to the
exposure process is held by the substrate stage PST. The baseline
amount is determined on the basis of the detection results of the
position information about the reference marks PFM, MFM, and then
the substrate P having been already subjected to the exposure
process is exported from the substrate stage PST. Accordingly, the
interior of the substrate holder PSH and the interior of the
substrate stage PST can be prevented from any inflow of the liquid
LQ.
[0122] A procedure is also conceived, in which the operation for
detecting the reference marks PFM, MFM is performed in order to
determine the baseline amount in a state in which the substrate P
before being subjected to the exposure process is held on the
substrate holder PSH. However, for example, when the reference mark
MFM is detected through the liquid. LQ, there is such a high
possibility that the liquid LQ may adhere to the alignment mark 1
on the substrate P before being subjected to the exposure process.
The substrate alignment system 5, which detects the alignment marks
on the substrate P, is constructed to perform the detection not
through the liquid LQ (in the dry state). Therefore, the detection
accuracy consequently deteriorated if the liquid LQ adheres to the
alignment mark 1 when the alignment mark 1 on the substrate P
before being subjected to the exposure process is detected by the
substrate alignment system 5. Therefore, it is preferable that the
substrate P, which is to be held by the substrate holder PSH when
the reference marks PFM, MFM are detected in order to determine the
baseline amount, is the substrate P after being subjected to the
exposure process.
[0123] It is desirable that the interior of the Z stage (substrate
stage PST) is prevented from any inflow of the liquid LQ by holding
the substrate P or the dummy substrate DP on the substrate holder
PSH or by using the mechanism shown in FIG. 10 when the liquid
immersion area AR2 is formed on the Z stage (substrate stage PST)
even when the reference member and the measuring member such as
various types of measuring sensors are not arranged on the Z stage
52 (substrate stage PST).
[0124] More specifically, desirable that the formation of the
liquid immersion area AR2 on the Z stage 52 (substrate stage PST)
is prohibited when the recess 60 of the Z stage 52 (substrate stage
PST) is not covered with the substrate P or the dummy substrate DP
irrelevant to the presence or absence of the reference member and
the measuring member such as various types of measuring sensors on
the Z stage 52 (substrate stage PST).
[0125] The control unit CONT can prohibit the liquid supply by the
liquid supply mechanism 10 and restrict the movement range of the Z
stage 52 (substrate stage PST) in the XY plane so that the optical
element 2 of the projection optical system PL is not opposed to the
Z stage 52 (substrate stage PST), for example, when the recess 60
of the Z stage 52 (substrate stage PST) is not covered with the
substrate P or the dummy substrate DP.
[0126] The control unit CONT integrally controls the operation of
the entire exposure apparatus EX. Therefore, the control unit CONT
can judge whether or not the recess 60 of the Z stage 52 (substrate
stage PST) is covered with, for example, the substrate P or the
dummy substrate DP. However, it is also possible to use a detector
for detecting whether or not the recess 60 is covered with the
substrate P or the dummy substrate DP as described later on.
[0127] It is desirable to provide the state in which the liquid LQ
is not disposed on (not adhered to) the alignment mark 1 on the
substrate P as described above when the alignment mark 1 on the
substrate P is detected by the substrate alignment system 5. It is
feared that the liquid LQ, which remains and adheres to the supply
nozzle 13, the recovery nozzle or the optical element 2, may be
dripped or scattered onto the substrate P when the substrate P
before being subjected to the exposure process, which is loaded on
the substrate stage PST, passes across the position under the
supply nozzle 13, the position under the recovery nozzle 23, or the
position under the optical element 2 of the projection optical
system PL. If the dripped liquid LQ is disposed on (adhered to) the
alignment mark 1 on the substrate P, then the substrate alignment
system 5 cannot measure the alignment mark 1, and any measurement
error is generated. Even when the measurement can be performed,
then the image of the alignment mark 1 and the waveform signal are
distorted, and the measurement is performed erroneously. As a
result, any inconvenience arises, for example, such that the
alignment measurement accuracy is deteriorated.
[0128] Further, a procedure is also conceived, in which the liquid
immersion area AR2 is formed at another position on the substrate
stage PST (for example, on the auxiliary plate 57 or on the upper
surface of the Z stage 52) separately from the substrate P held by
the substrate stage PST, while the substrate alignment system 5
measures the alignment mark 1 on the substrate P not through the
liquid LQ. Furthermore, a procedure is also conceived, in which the
liquid immersion area AR2 is formed (locally) on a part of the
substrate P, while the alignment mark 1 is detected, outside the
liquid immersion area AR2, by the substrate alignment system 5 not
through the liquid LQ. Also in this case, if the liquid LQ is
scattered from the liquid immersion area AR2, and/or the liquid LQ
is not recovered sufficiently, then an inconvenience arises such
that the alignment mark 1 is measured by the substrate alignment
system 5 in a state in which the liquid LQ is arranged on the
alignment mark 1 on the substrate P.
[0129] Accordingly, the control unit CONT determines the movement
locus of the substrate stage PST so that the alignment mark 1 on
the substrate P, which is to be arranged in the detection area for
the substrate alignment system 5, does not pass across the position
under the supply nozzle 13, the recovery nozzle 23, or the optical
element 2 of the projection optical system PL. The control unit
CONT successively measures the plurality of alignment marks 1 on
the substrate P respectively by using the substrate alignment
system 5 while moving the substrate stage PST on the basis of the
determined movement locus,
[0130] FIG. 11 explains the operation for successively measuring
the plurality of alignment marks 1 on the substrate P respectively
by the substrate alignment system 5. With reference to FIG. 11, the
supply nozzles 13 and the recovery nozzles 23 are arranged in the
vicinity of the optical element 2 of the projection optical system
PL. The substrate alignment system 5 is arranged on the +X side of
the optical element 2, the supply nozzles 13, and the recovery
nozzles 23. When the plurality of alignment marks 1 on the
substrate P are successively measured respectively by using the
substrate alignment system 5 in the positional relationship as
described above, the control unit CONT firstly arranges the
alignment mark 1 accompanied with the shot area provided on the
most -X side on the substrate P in the detection area of the
substrate alignment system 5 as shown in FIG. 11A to measure the
alignment mark 1 by the substrate alignment system 5. For example,
the control unit CONT arranges the alignment mark 1 accompanied,
for example, with the shot area S10 or S11 on the substrate P (see
FIG. 4) in the detection area of the substrate alignment system S.
In the following description, the alignment mark 1, which is
firstly measured, is referred to as "first alignment mark".
[0131] On this assumption, when the first alignment mark 1 on the
substrate P is arranged in the detection area of the substrate
alignment system 5 after the substrate P before being subjected to
the exposure process is loaded on the substrate stage PST at the
substrate exchange position RP (see FIG. 9), the control unit CONT
moves the substrate stage PST so that at least the alignment mark
1, which is the measurement objective for the substrate alignment
system 5 and which is included in the plurality of alignment marks
1 on the substrate P, does not pass across the positions under the
supply nozzles 13, the recovery nozzles 23, and the optical element
2. Accordingly, the first alignment mark 1 is arranged in the
detection area of the substrate alignment system 5 without passing
across, for example, the positions under the supply nozzles 13.
Therefore, it is possible to avoid the inconvenience which would be
otherwise caused such that the first alignment mark 1 is measured
by the substrate alignment system 5 in a state in which the liquid
LQ dripped, for example, from the supply nozzle 13, is disposed
onto the first alignment mark 1.
[0132] After the completion of the detection of the first alignment
mark 1, the control unit CONT moves the substrate stage PST toward
the -X side so that a second alignment mark 1 (for example, the
alignment mark 1 accompanied by the shot area S12 or S9), which is
provided on the +X side as compared with the first alignment mark
1, is arranged in the detection area of the substrate alignment
system 5. In this procedure, the control unit CONT determines the
movement locus of the substrate stage PST so that the alignment
mark 1 as the measurement objective does not pass across the
position under the supply nozzle 13 or the like to arrive at the
detection area of the substrate alignment system 5. Therefore,
after the substrate P is loaded on the substrate stage PST, the
second alignment mark 1 does not pass across the position under the
supply nozzle 13 or the like during the period until the second
alignment mark 1 on the substrate P is arranged in the detection
area of the substrate alignment system 5. Therefore, the
inconvenience is avoided, which would be otherwise caused such that
the liquid LQ dripped from the supply nozzle 13 or the like is
arranged on the second alignment mark 1. It is allowable that the
first alignment mark 1, which has been already measured by the
substrate alignment system 5, passes across the position under the
supply nozzle 13 or the like.
[0133] The operation is similarly performed thereafter as shown in
FIG. 11B. That is, third and fourth alignment marks 1, which are
provided on the +X side as compared with the second alignment mark
1, are successively arranged in the detection area of the substrate
alignment system 5 by the control unit CONT to perform the
measurement. The operation as described above is performed by the
control unit CONT by controlling the substrate stage-driving unit
PSTD on the basis of the exposure recipe while monitoring the
position of the substrate stage PST with the laser interferometer
56.
[0134] In this procedure, the control unit CONT moves the substrate
stage PST toward the -X side to successively arrange the alignment
marks 1 in the order from the alignment mark 1 on the -X side to
the alignment mark 1 on the +X side in the detection area of the
substrate alignment system 5. However, when the substrate alignment
system 5 is provided on the -X side of the projection optical
system PL, the substrate stage PST is moved toward the +X side. The
order of the detection of the alignment marks 1 is not limited to
the order along with the X ax direction. As described above, it is
unnecessary that of the plurality of alignment marks 1 provided on
the substrate 2 are detected by the substrate alignment system 5.
Therefore, any alignment mark 1, which is not the measurement
objective for the substrate alignment system 5, is permitted to
pass across the position under the supply nozzle 13 or the like. In
principle, it is enough that the alignment mark 1, which is the
measurement objective before being arranged in the detection area
of the substrate alignment system 5, does not pass across the
position under the supply nozzle 13 or the like.
[0135] As explained above, the movement locus of the substrate
stage PST, which is to be set in order to arrange the alignment
mark 1 in the detection area of the substrate alignment system 5,
is determined by the control unit CONT depending on the positional
relationship between the substrate alignment system 5 and the
supply nozzles 13 (as well as the recovery nozzles 23 and the
optical element 2). Accordingly, it is possible to avoid the
inconvenience of the adhesion of the liquid LQ which would be
otherwise caused by the passage of the alignment mark 1 to be
measured by the substrate alignment system 5 across the position
under the supply nozzle 13 or the like. Therefore, it is possible
to avoid the inconvenience which would be otherwise caused such
that the substrate alignment system 5 measures the alignment mark 1
in the state the liquid LQ is adhered thereto. Thus, it is possible
to avoid the measurement error and the erroneous measurement.
Therefore, the rate of operation of the exposure apparatus EX is
improved, and the exposure accuracy can be maintained in a highly
sophisticated manner.
[0136] In the case of the embodiment explained with reference to
FIG. 11, the alignment marks 1 may be detected by the substrate
alignment system 5 in a state in which the liquid LQ is retained on
the image plane side of the projection optical system PL. In this
procedure, the liquid immersion area AR2 is formed on the upper
surface of the substrate stage PST (Z stage 52), on the portion
ranging over the upper surface of the substrate stage PST and the
surface of the substrate P, or on the surface of the substrate P.
However, as also clarified from FIG. 11, the control unit CONT
determines the movement locus of the substrate stage PST so that
the alignment mark 1 of the substrate P is detected by the
substrate alignment system 5 before the alignment mark 1 makes
contact with the liquid LQ in the liquid immersion area AR2 (see
FIG. 1). Therefore, it is possible to avoid the inconvenience which
would be otherwise caused such that the substrate alignment system
5 measures the alignment mark 1 in a state in which the liquid LQ
is adhered to the alignment mark 1.
[0137] In this embodiment, the alignment mark 1 on the substrate P
does not pass across the position under the supply nozzle 13 or the
like before being arranged in the detection area of the substrate
alignment system 5. However, it is also allowable that the movement
locus of the substrate stage PST is determined so that the
reference mark PFM before being arranged in the detection area of
the substrate alignment system 5 does not pass across the position
under the supply nozzle 13 or the like. The movement locus of the
substrate stage PST is determined so that not only the alignment
marks 1 and the reference mark PFM but also any mark (measurement
objective) on the substrate stage PST to be measured in the dry
state does not pass across the position under the member from which
the liquid LQ can be dripped. Accordingly, it is possible to
improve the mark measurement accuracy not through the liquid
LQ.
[0138] The embodiment described above is illustrative of the
movement locus adopted when the substrate stage PST is moved from
the substrate exchange position RP to the position in the vicinity
of the projection optical system PL (exposure process position EP)
and/or when the plurality of alignment marks 1 on the substrate P
are measured. However, it is preferable that the movement locus of
the substrate stage PST is determined so that the alignment mark 1
on the substrate P does not pass across the position under the
supply nozzle 13 or the like as well, for example, when the
alignment mark 1 on the substrate P is measured after measuring the
reference marks PFM, MFM on the reference member 3. For example,
with reference to FIG. 12, when the reference mark MFM on the
reference member 3 is measured through the liquid LQ by using the
mask alignment system 6, the control unit CONT measures the
reference mark MFM in a state in which the liquid immersion area
AR2 is formed on the reference member 3. After the measurement of
the reference mark MFM through the liquid LQ is completed, the
control unit CONT recovers the liquid LQ from the surface of the
reference member 3 by using, for example, the liquid recovery
mechanism 20. When the alignment mark 1 on the substrate P is
arranged in the detection area of the substrate alignment system 5
thereafter, the control unit CONT moves the XY stage 53 while
monitoring the output of the laser interferometer 56 so that the
supply nozzle 13 or the like is advanced along the broken line
arrow K shown in FIG. 12. The control unit CONT arranges the first
alignment mark 1 (for example, the alignment mark 1 accompanied
with the shot area S10) in the detection area of the substrate
alignment system 5. Also in this case, the alignment mark 1 before
being measured by the substrate alignment system 5 does not pass
across the position under the supply nozzle 13 or the like.
Therefore, the liquid LQ, which is dripped from the supply nozzle
13 or the like, is not adhered thereto.
[0139] When any detection error arises due to the adhesion of the
liquid to the alignment mark 1, the following operation may be
performed in the same manner as in the case in which any detection
error arises due to the adhesion of any foreign matter to the
alignment mark 1. That is, the detection of the concerning
alignment mark may be stopped, and another alignment mark disposed
in the vicinity thereof may be detected in place of the concerning
alignment mark. Alternatively, the substrate P itself may he
handled as a defective substrate.
[0140] The mark image and the signal waveform, which are obtained
when the alignment mark on the substrate P is detected in the dry
state by the substrate alignment system 5, may be previously
stored. When the mark image and/or the signal waveform, which is
obtained when the alignment mark 1 is actually detected by the
substrate alignment system 5, is greatly different from the stored
data, then it is judged that the liquid adheres to at least one of
the alignment mark and the optical element disposed at the terminal
end of the substrate alignment system 5, and the detection error is
outputted to urge the operator or the like to wipe out the adhered
liquid.
[0141] Similarly, mark image and the signal waveform, which are
obtained when the reference mark PFM is measured in the dry state
by the substrate alignment system 5, may be stored beforehand. When
the mark image and/or the signal waveform, which is actually
obtained for the reference mark PFM by the substrate alignment
system 5, for example, upon the measurement of the baseline amount,
is greatly different from the stored data, then it is judged that
the liquid adheres to at least one of the reference mark PFM and
the optical element disposed at the terminal end of the substrate
alignment system 5, and the detection error is outputted to urge
the operator or the like to wipe out the adhered liquid.
[0142] The mark image and the signal waveform to be stored may be
obtained by the substrate alignment system 5 in the exposure
apparatus EX. Alternatively, the mark image and the signal waveform
to be stored may be obtained outside the exposure apparatus EX.
[0143] An uneven illuminance sensor 400 as disclosed, for example,
in Japanese Patent Application Laid-open No. 57-117238 and a
spatial image-measuring sensor 500 as disclosed, for example, in
Japanese Patent Application Laid-open No. 2002-14005 are provided
on the substrate stage PST shown in FIG. 12. It is assumed that the
measurement process is performed through the liquid LQ in a state
in which the liquid immersion area AR2 i s formed on each of the
measuring sensors 400, 500. Also in this case, the control unit
CONT performs the liquid recovery by using, for example, the liquid
recovery mechanism 20 after the completion of the measurement
process by the sensors 400, 500. When the alignment mark 1 on the
substrate P is arranged in the detection area of the substrate
alignment system 5, the control unit CONT determines the movement
locus of the substrate stage PST so that the alignment mark 1 on
the substrate P as the measurement objective for the substrate
alignment system 5 does pass across the position under the supply
nozzle 13 or the like.
[0144] FIG. 13 schematically shows another embodiment of the
present invention. With reference to FIG. 13A, the exposure
apparatus EX includes an attracting and holding mechanism 90 which
attracts and holds the substrate P on the substrate holder PSH. The
attracting and holding mechanism 90 includes suction holes 91 which
are provided at a plurality of positions on the upper surface of
the substrate holder PSH respectively, and a vacuum system 93 which
is connected via a flow passage 92 to each of the plurality of
suction holes 91. The control unit CONT drives the vacuum system
93, and thus the back surface of the substrate P placed on the
upper surface of the substrate holder PSH is held by vacuum suction
by the aid of the suction holes 91.
[0145] The information, which relates to the pressure of the vacuum
system 93 or the flow passage 92 of the attracting and holding
mechanism 90, is monitored by the pressure detector 94. The
pressure detector 94 is capable of detecting whether or not the
substrate P (or the dummy substrate DP) is held on the substrate
holder PSH on the basis of the information about the detected
pressure. That is, the pressure detector 94 judges that the
substrate P is not held on the substrate holder PSH when the
suction operation is executed by the attracting and holding
mechanism 90 and the pressure is not lowered. The pressure detector
94 judges that the substrate P is held on the substrate holder PSH
when the pressure is lowered. The detection result and the judgment
result of the pressure detector 94 are outputted to the control
unit CONT.
[0146] A valve 14, which opens/closes the flow passage of the
supply tube 12, is provided at an intermediate position of the
supply tube 12 of the quid supply mechanism 10. The operation of
valve 14 is controlled by the control unit CONT.
[0147] When the substrate P is held on the substrate holder PSH as
shown in FIG. 13A, the pressure detector 94 can detect that the
substrate P is held on the substrate holder PSH on the basis of the
information about the pressure as described above. When the
pressure detector 94 detects the substrate P, the control unit CONT
issues the instruction to enable the liquid supply to the liquid
supply mechanism 10 on the basis of the detection result (judgment
result) of the pressure detector 94.
[0148] On the other hand, as shown in FIG. 13B, when the substrate
P is not held on the substrate holder PSH, the pressure detector 94
can detect that the substrate P is not held on the substrate holder
PSH on the basis of the information about the pressure. When the
pressure detector 94 does not detect the substrate P, the control
unit CONT issues the instruction to disable the liquid supply to
the liquid supply mechanism 10 on the basis of the detection result
(judgment result) of the pressure detector 94. The liquid supply
mechanism 10, which has received the instruction of the control
unit CONT, closes the flow passage of the supply tube 12, for
example, by the valve 14. Accordingly, the control unit CONT stops
the liquid supply by the liquid supply mechanism 10.
[0149] When the liquid immersion area AR2 is formed and/or the
liquid supply is executed by the liquid supply mechanism 10 in the
state in which the substrate P or the dummy substrate DP is not
held on the substrate holder PSH as described above, there is such
a possibility that the liquid LQ inflows into the substrate holder
PSH and into the substrate stage PST. For example, if the liquid LQ
inflows into the substrate stage PST, then any rust appears, and
any inconvenience arises in the sliding portions and the electric
equipment arranged therein. An extremely long period of time is
required for the restoration. On the other hand, if the holding
surface of the substrate holder PSH catches the liquid LQ, an
inconvenience arises such that the liquid LQ flows into the vacuum
system 93 via the suction hole 91. If the liquid LQ adheres to the
holding surface of the substrate holder PSH, the following
inconvenience occurs as well. That is, the liquid LQ functions as a
lubricating film when the substrate P is placed, and the substrate
P is held in a deviated state with respect to the desired position.
Accordingly, as in the embodiment of the present invention, the
operation of the liquid supply mechanism 10 is controlled depending
on whether or not the substrate P or the dummy substrate DP is held
on the substrate holder PSH. Accordingly, it is possible to avoid
the adhesion of the liquid LQ to the holding surface of the
substrate holder PSH and the inflow of the liquid into the
substrate stage PST. When the substrate P or the dummy substrate DP
is not held on the substrate holder PSH, the control unit CONT
stops the liquid supply by the liquid supply mechanism 10.
Accordingly, it is possible to avoid, for example, the inflow of
the liquid into the substrate stage PST.
[0150] In this embodiment, it is judged whether or not the
substrate P and/or the dummy substrate DP is held on the substrate
holder PSH on the basis of the detection result of the pressure
detector 94. However, for example, a contact type sensor for
detecting the presence or absence of the substrate may be provided
for the substrate stage PST and/or the substrate holder PSH, and
the operation of the liquid supply mechanism 10 may be controlled
on the basis of an obtained detection result. Alternatively, the
focus-detecting system 4 as described above may be used to judge
whether or not the substrate P or the dummy substrate DP is held on
the substrate holder PSH, and the operation of the liquid supply
mechanism 10 may be controlled on the basis of an obtained result.
Further, the Z stage 52 (substrate stage PST) may be prohibited
from the movement to the positions under the supply nozzle 13, the
recovery nozzle 23, and the optical element so that the liquid
immersion area AR2 is not formed on the Z stage 52 (substrate stage
PST) when the substrate P (or the dummy substrate DP) is not held
on the substrate holder PSH.
[0151] The control unit CONT may change the movable area of the
substrate stage PST depending on the detection result of the
pressure detector 94. There is such a possibility that the liquid
LQ, which remains on or adheres to the supply nozzle 13, the
recovery nozzle 23, or the optical element 2 of the projection
optical system PL, drips to cause the inflow into the substrate
holder PSH and/or into the substrate stage PST, even when the
liquid supply by the liquid supply mechanism 10 is stopped when the
substrate P (or the dummy substrate DP) is not held on the
substrate holder PSH as in the embodiment explained with reference
to FIG. 13. The following inconvenience also arises in the
situation as described above. That is, for example, any electric
leakage is caused in the electric equipment in the substrate stage
PST, any rust appears, and the liquid LQ flows into the vacuum
system 93 via the suction hole 91. Further, the liquid LQ, which
has dripped onto the holding surface of the substrate holder PSH,
functions as a lubricating film, and the substrate P is held in a
state of being deviated with respect to the desired position.
Accordingly, the control unit CONT changes the movable area of the
substrate stage PST depending on the detection result of the
detector 94 which detects whether or not the substrate P is held on
the substrate holder PSH.
[0152] Specifically, when the substrate P the dummy substrate DP)
is not held on the substrate holder P other words, when the
pressure detector 94 does not detect the substrate P, then the
control unit CONT sets that the movable area of the substrate stage
PST to be the area in which the substrate holder PSH is not
positioned under the supply nozzles 13, the recovery nozzles 23,
and the optical element 2. When the substrate P is not held on the
substrate holder PSH, the control unit CONT moves the substrate
stage PST so that the substrate holder PSH does not pass across the
position under the supply nozzle 13 or the like, while monitoring
the output of the laser interferometer 56. Accordingly, even when
the liquid LQ drips from the supply nozzle 13 or the like, it is
possible to avoid, for example, the inflow of the liquid LQ into
the substrate holder PSH and into the substrate stage PST.
[0153] In the embodiment described above, the supply of the liquid
LQ from the supply nozzles 13 is started when the liquid immersion
area AR2 is formed on the substrate stage PST. However, the liquid
immersion area AR2 can be also formed on the substrate stage PST
such that the liquid, which is retained between the projection
optical system PL and any predetermined object different from the
substrate stage PST, is not recovered, and the liquid immersion
area AR2, which is formed on the predetermined object, is moved
onto the substrate stage PST.
[0154] In the embodiment described above, the reference mark PFM
and the alignment marks 1 on the substrate P are detected not
through the liquid, and the detection of the reference mark MFM is
executed through the liquid. However, the invention, which relates
to, for example, the provision of the liquid repellence of the
surface of the reference member 3, the provision of the upper
surface of the reference member 3 free from any difference in
level, and the use of the dummy substrate DP, is also applicable
when any arrangement, in which the reference mark PFM and the
reference mark MFM can be simultaneously detected, is adopted. The
invention is also applicable when the reference mark PFM and the
alignment marks 1 on the substrate P are detected through the
liquid. An exposure apparatus, which is constructed such that the
reference mare PFM and the reference mark MFM can be simultaneously
detected, is disclosed, for example, in Japanese Patent Application
Laid-open No. 4-45512 (corresponding to U.S. Pat. No. 5,138,176),
contents of which are incorporated herein by reference within a
range of permission of the domestic laws and ordinances of the
state designated or selected in this international application.
[0155] When the liquid immersion area and the non-liquid immersion
area can be formed separately on the reference member 3, it is also
allowable to adopt an arrangement in which the detection of the
reference mark PFM without the liquid and the detection of the
reference mark MFM with the liquid can be performed simultaneously,
as disclosed in Japanese Patent Application Laid-open No. 4-45512.
In this case, for example, Step SA3 and Step SA4 can be performed
simultaneously in the alignment sequence shown in FIG. 6.
Therefore, this arrangement is advantageous in view of the
throughput. It goes without saying that an arrangement, in which
the detection of the reference mark PFM and the detection of the
reference mark MFM can be performed simultaneously, may be adopted
as disclosed in Japanese Patent Application Laid-open No. 4-45512,
when the substrate alignment system 5 is constructed such that the
reference mark PFM and the alignment marks 1 on the substrate P are
detected through the liquid.
[0156] In the embodiment described above, the two reference marks,
i.e., the reference mark PFM and the reference mark MFM are
provided on the reference member. However, Step SA3 and Step SA4
can be also performed using a single reference mark
(reference).
[0157] As described above, pure water is used as the liquid LQ in
the embodiments of the present invention. Pure water is
advantageous in that pure water is available in a large amount with
ease, for example, in the semiconductor production factory, and
pure water exerts no harmful influence, for example, on the optical
element (lens) and the photoresist on the substrate P. Further,
pure water exerts no harmful influence on the environment, and the
content of impurity is extremely low. Therefore, it is also
expected to obtain the function to wash the surface of the
substrate P and the surface of the optical element provided at the
end surface of the projection optical system PL. When the purity of
pure water supplied from the factory or the like is low, it is also
allowable that the exposure apparatus is provided with an ultra
pure water-producing unit.
[0158] It is approved that the refractive index n of pure water
(water) with respect to the exposure light beam EL having a
wavelength of about 193 nm is approximately 1.44. When the ArF
excimer laser beam (wavelength: 193 nm) is used as the light source
of the exposure light beam EL, then the wavelength is shortened on
the substrate P by 1/n, i.e., to about 134 nm, and a high
resolution is obtained. Further, the depth of focus is magnified
about n times, i.e., about 1.44 times as compared with the value
obtained in the air. Therefore, when it is enough to secure an
approximately equivalent depth of focus as compared with the case
of the use in the air, it is possible to further increase the
numerical aperture of the projection optical system PL. Also in
this viewpoint, the resolution is improved.
[0159] When the liquid immersion method is used as described above,
the numerical aperture NA of the projection optical system is 0.9
to 1.3 in some cases. When the numerical aperture NA of the
projection optical system is large as described above, it is
desirable to use the polarized illumination, because the image
formation performance is deteriorated due to the polarization
effect in some cases with the random polarized light which has been
hitherto used as the exposure light beam. In this case, it is
appropriate that the linear polarized illumination, which is
adjusted to the longitudinal direction of the line pattern of the
line-and-space pattern of the mask (reticle), is effected so that
the diffracted light of the S-polarized light component (component
in the polarization direction along with the longitudinal direction
of the line pattern) is dominantly allowed to outgo from the
pattern of the mask (reticle). When the space between the
projection optical system PL and the resist coated on the surface
of the substrate P is filled with the liquid, the diffracted light
of the S-polarized light component, which contributes to the
improvement in the contrast, has the high transmittance on the
resist surface, as compared with the case in which the space
between the projection optical system PL and the resist coated on
the surface of the substrate P is filled with the air (gas).
Therefore, it is possible to obtain the high image formation
performance even when the numerical aperture NA of the projection
optical system exceeds 1.0. Further, it is more effective to
appropriately combine, for example, the phase shift mask and the
oblique incidence illumination method (especially the dipole
illumination method) adjusted to the longitudinal direction of the
line pattern as disclosed in Japanese Patent Application Laid-open
No. 6-188169.
[0160] Further, it is also effective to use the combination of the
oblique incidence illumination method and the polarized
illumination method in which the linear polarization is effected in
the tangential (circumferential) direction of the circle having the
center of the optical axis as disclosed in Japanese Patent
Application Laid-open No. 6-53120, without being limited to only
the linear polarized illumination (S-polarized illumination)
adjusted to the longitudinal direction of the line pattern of the
mask (reticle). In particular, when the pattern of the mask
(reticle) includes not only the line pattern extending in one
predetermined direction, but the pattern also includes the line
patterns extending in a plurality of different directions in a
mixed manner, then possible to obtain the high image formation
performance even when the numerical aperture NA of the projection
optical system is large, by using, in combination, the zonal
illumination method and the polarized illumination method in which
the light is linearly polarized in the tangential direction of the
circle having the center of the optical axis, as disclosed in
Japanese Patent Application Laid-open No. 6-53120 as well.
[0161] In the embodiments of the present invention, the optical
element 2 is attached to the end portion of the projection optical
system PL. Accordingly, the lens makes it possible to adjust the
optical characteristics of the projection optical system PL, for
example, the aberration (for example, spherical aberration and
comatic aberration). The optical element, which is attached to the
end portion of the projection optical system PL, may be an optical
plate which is usable to adjust the optical characteristics of the
projection optical system PL. Alternatively, the optical element
may be a plane parallel plate or parallel flat plate through which
the exposure light beam EL is transmissive. When the optical
element, which makes contact with the liquid LQ, is the plane
parallel plate which is cheaper than the lens, it is enough that
the plane parallel plate is merely exchanged immediately before
supplying the liquid LQ even when any substance (for example, any
silicon-based organic matter), which deteriorates the transmittance
of the projection optical system PL, the illuminance of the
exposure light beam EL on the substrate P, and the uniformity of
the illuminance distribution, is adhered to the plane parallel
plate, for example, during the transport, the assembling, and/or
the adjustment of the exposure apparatus EX. An advantage is
obtained such that the exchange cost is lowered as compared the
case in which the optical element to make contact with the liquid
LQ is the lens. That is, the surface of the optical element to make
contact with the liquid LQ is dirtied, for example, due to the
adhesion of scattered particles generated from the resist by being
irradiated with the exposure light beam EL or any impurity
contained in the liquid LQ. Therefore, it is necessary to
periodically exchange the optical element. However, when the
optical element is the cheap plane parallel plate, then the cost of
the exchange part is low as compared with the lens, and it is
possible to shorten the time required for the exchange. Thus, it is
possible to suppress the increase in the maintenance cost (running
cost) and the decrease in the throughput.
[0162] When the pressure, which is generated by the flow of the
liquid LQ, is large between the substrate P and the optical element
disposed at the end portion of the projection optical system PL, it
is also allowable that the optical element is tightly fixed so that
the optical element is not moved by the pressure, instead of making
the optical element to be exchangeable.
[0163] In the embodiments of the present invention, the space
between the projection optical system PL and the surface of the
substrate P is filled with the liquid LQ. However, for example, it
is also allowable to adopt an arrangement in which the space is
filled with the liquid LQ in such a state that a cover glass formed
of a parallel flat plate is attached to the surface of the
substrate P.
[0164] The exposure apparatus, to which the liquid immersion method
is applied as described above, is constructed such that the wafer
substrate P is exposed while filling the optical path space on the
outgoing side of the terminal end optical element 2 of the
projection optical system PL with the liquid (pure water). However,
the optical path space, which is disposed on the incoming side of
the terminal end optical element 2 of the projection optical system
PL, may be also filled with the liquid (pure water) as disclosed in
International Publication No. 2004/019128.
[0165] The liquid LQ is water in the embodiments of the present
invention. However, the liquid LQ may be any liquid other than
water. For example, when the light source of the exposure light
beam EL is the F.sub.2 laser, the F.sub.2 laser beam is not
transmitted through water. Therefore, liquids preferably usable as
the liquid LQ may include, for example, fluorine-based liquid such
as fluorine-based oil and perfluoropolyether (PFPE) through which
the F.sub.2 laser beam is transmissive. In this case, the portion,
which makes contact with the liquid LQ, is subjected to a
liquid-attracting treatment by forming, for example, a thin film
with a substance having a molecular structure containing fluorine
having small polarity. Alternatively, other than the above, it is
also possible to use, as the liquid LQ, liquids (for example, cedar
oil) which have the transmittance with respect to the exposure
light beam EL, which have the refractive index as high as possible,
and which are stable against the photoresist coated on the surface
of the substrate P and the projection optical system PL. Also in
this case, the surface treatment is performed depending on the
polarity of the liquid LQ to be used.
[0166] The substrate P, which is usable in the respective
embodiments described above, is not limited to the semiconductor
wafer for producing the semiconductor device. The applicable
substrates include, for example, the glass substrate for the
display device, the ceramic wafer for the thin film magnetic head,
and the master plate (synthetic quartz, silicon wafer) for the mask
or the reticle to be used for the exposure apparatus
[0167] As for the exposure apparatus EX, the present invention is
also applicable to the scanning type exposure apparatus (scanning
stepper) based on the step-and-scan system for performing the
scanning exposure for the pattern of the mask M by synchronously
moving the mask M and the substrate P as well as the projection
exposure apparatus (stepper) based on the step-and-repeat system
for performing the full field exposure for the pattern of the mask
M in a state in which the mask M and the substrate P are allowed to
stand still, while successively step-moving the substrate P. The
present invention is also applicable to the exposure apparatus
based on the step-and-stitch system in which at least two patterns
are partially overlaid and transferred on the substrate P.
[0168] The present invention is also applicable to a twin-stage
type exposure apparatus provided with two stages which are movable
independently in the XY directions while placing process objective
substrates such as wafers separately thereon. The structure and the
exposure operation of the twin-stage type exposure apparatus are
disclosed, for example, in Japanese Patent Application Laid-open
Nos. 10-163099 and 10-214783 (corresponding to U.S. Pat. Nos.
6,341,007, 6,400,941, 6,549,269, and 6,590,634), Published Japanese
Translation of PCT International Publication for Patent Application
No. 2000-505958 (corresponding to U.S. Pat. No. 5,969,441), and
U.S. Pat. No. 6,208,407, contents of which are incorporated herein
by reference within a range of permission of the domestic laws and
ordinances of the state designated or selected in this
international application.
[0169] In the case of the twin stage type exposure apparatus
provided with the two stages, the exposure station for performing
the exposure for the substrate and the alignment station for
performing the positional adjustment for the shot area on the
substrate are provided independently in some cases. In this
arrangement, in order to improve the throughput, a substrate on the
second stage is subjected to the alignment in the alignment station
when the substrate on the first stage is subjected to the exposure
in the exposure station. After the substrate on the second stage is
subjected to the alignment, the second stage is moved to the
exposure station, and the substrate, which has been subjected to
the positional adjustment in the alignment station, is subjected to
the exposure in the exposure station. During this process, the
relative position with respect to the reference mark provided on
the substrate stage as explained in the foregoing embodiment is
determined for the substrate on the second stage in the alignment
station. When the second stage is moved to the exposure station,
the image formation position is determined on the basis of the
reference mark in the exposure station as well. Therefore, the
reference mark, which is of the type having been explained in the
foregoing embodiment, is effectively utilized in the exposure and
alignment stations of the exposure apparatus of the twin stage
type.
[0170] In the embodiment described above, the exposure apparatus,
in which the space between the projection optical system PL and the
substrate P is locally filled with the liquid, is adopted. However,
the present invention is also applicable to the liquid immersion
exposure apparatus in which the entire surface of the substrate as
the exposure objective is covered with the liquid. The structure
and the exposure operation of the liquid immersion exposure
apparatus in which the entire surface of the substrate as the
exposure objective is covered with the liquid are described in
detail, for example, in Japanese Patent Application Laid-open Nos.
6-124873 and 10-303114 and U.S. Pat. No. 5,825,043, contents of
which are incorporated herein by reference within a range of
permission of the domestic laws and ordinances of the state
designated or selected in this international application.
[0171] The present invention is also applicable to the exposure
apparatus provided with the exposure stage which is movable while
holding the process objective substrate such as the wafer and the
measuring stage which includes measuring members such as measuring
sensors and various types of reference members. In this case, at
least parts of the reference member and the various types of
measuring sensors arranged on the substrate stage PST the
embodiment described above can be arranged on the measuring stage.
The exposure apparatus provided with the exposure stage and the
measuring stage is described, for example, in Japanese Patent
Application Laid-open No. 11-135400, contents of which are
incorporated herein by reference within a range of permission of
the domestic laws and ordinances of the state designated or
selected in this international application.
[0172] As for the type of the exposure apparatus EX, the present
invention is not limited to the exposure apparatus for the
semiconductor device production for exposing the substrate P with
the semiconductor device pattern. The present invention is also
widely applicable, for example, to the exposure apparatus for
producing the liquid crystal display device or for producing the
display as well as the exposure apparatus for producing, for
example, the thin film magnetic head, the image pickup device
(CCD), the reticle, or the mask,
[0173] When the linear motor is used for the substrate stage PST
and/or the mask stage MST, it is allowable to use any one of those
of the air floating type based on the use of the air bearing and
those of the magnetic floating type based on the use of the
Lorentz's force or the reactance force. Each of the stages PST, MST
may be either of the type in which the movement is effected along
the guide or of the guideless type in which no guide is provided.
An example of the use of the linear motor for the stage is
disclosed in U.S. Pat. Nos. 5,623,853 and 5,528,118, contents of
which are incorporated herein by reference respectively within a
range of permission of the domestic laws and ordinances of the
state designated or selected in this international application.
[0174] As for the driving mechanism for each of the stages PST,
MST, it is also allowable to use a plane motor in which a magnet
unit provided with two-dimensionally arranged magnets and an
armature unit provided with two-dimensionally arranged coils are
opposed to one another, and each of stages PST, MST is driven by
the electromagnetic force. In this arrangement, any one of the
magnet unit and the armature unit is connected to the stage PST,
MST, and the other of the magnet unit and the armature unit is
provided on the side of the movable surface of the stage PST,
MST.
[0175] The reaction force, which is generated accordance with the
movement of the substrate stage PST, may be mechanically released
to the floor (ground) by using a frame member so that the reaction
force is not transmitted to the projection optical system PL. The
method for handling the reaction force is disclosed in detail, for
example, in U.S. Pat. No. 5,528,118 (Japanese Patent Application
Laid-open No. 8-166475), contents of which are incorporated herein
by reference within a range of permission of the domestic laws and
ordinances of the state designated or selected in this
international application.
[0176] The reaction force, which is generated in accordance with
the movement of the mask stage MST, may be mechanically released to
the floor (ground) by using a frame member so that the reaction
force is not transmitted to the projection optical system PL. The
method for handling the reaction force is disclosed in detail, for
example, in U.S. Pat. No. 5,874,820 (Japanese Patent Application
Laid-open No. 8-330224), contents of which are incorporated herein
by reference within a range of permission of the domestic laws and
ordinances of the state designated or selected in this
international application.
[0177] As described above, the exposure apparatus EX according to
the embodiment of the present invention is produced by assembling
the various subsystems including the respective constitutive
elements as defined in claims so that the predetermined mechanical
accuracy, the electric accuracy, and the optical accuracy are
maintained. In order to secure the various accuracies, those
performed before and after the assembling include the adjustment
for achieving the optical accuracy for the various optical systems,
the adjustment for achieving the mechanical accuracy for the
various mechanical systems, and the adjustment for achieving the
electric accuracy for the various electric systems. The steps of
assembling the various subsystems into the exposure apparatus
include, for example, the mechanical connection, the wiring
connection of the electric circuits, and the piping connection of
the air pressure circuits in correlation with the various
subsystems. It goes without saying that the steps of assembling the
respective individual subsystems are performed before performing
the steps of assembling the various subsystems into the exposure
apparatus. When the steps of assembling the various subsystems into
the exposure apparatus are completed, the overall adjustment is
performed to secure the various accuracies as the entire exposure
apparatus. It is desirable that the exposure apparatus is produced
in a clean room in which, for example, the temperature and the
cleanness are managed.
[0178] As shown in FIG. 14, the microdevice such as the
semiconductor device is produced by performing, for example, a step
201 of designing the function and the performance of the
microdevice, a step 402 of manufacturing a mask (reticle) based on
the designing step, a step 203 of producing a substrate as a base
material for the device, an exposure process step 204 of exposing
the substrate with a pattern of the mask by using the exposure
apparatus EX of the embodiment described above, a step 205 of
assembling the device (including a dicing step, a bonding step, and
a packaging step), and an inspect step 206.
[0179] According to the present invention, the alignment process
can be performed accurately. Therefore, it is possible to
accurately form the desired pattern on the substrate. Further, it
is possible to avoid any inflow of the liquid, for example, into
the substrate stage.
* * * * *