U.S. patent application number 11/871328 was filed with the patent office on 2008-02-14 for stage device and exposure apparatus.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Keiji EMOTO.
Application Number | 20080036981 11/871328 |
Document ID | / |
Family ID | 34858434 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080036981 |
Kind Code |
A1 |
EMOTO; Keiji |
February 14, 2008 |
Stage Device And Exposure Apparatus
Abstract
A stage device for driving a movable element, mounted with an
object thereon, by using a plane motor, including: (i) a stator
unit having a coil group; and (ii) the movable element which moves
on the stator unit, the stator unit including: (a) a first region
where the object is to be subjected to a first process; and (b) a
second region where the object is to be subjected to a second
process, wherein the coil group in the stator unit is
temperature-controlled independently between the first and second
regions.
Inventors: |
EMOTO; Keiji;
(Utsunomiya-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
34858434 |
Appl. No.: |
11/871328 |
Filed: |
October 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11074642 |
Mar 9, 2005 |
7282820 |
|
|
11871328 |
Oct 12, 2007 |
|
|
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Current U.S.
Class: |
355/30 ;
310/12.06; 310/12.29 |
Current CPC
Class: |
G03F 7/70875 20130101;
Y10T 74/20201 20150115; G03F 7/70758 20130101 |
Class at
Publication: |
355/030 ;
310/012 |
International
Class: |
G03B 27/26 20060101
G03B027/26; G03B 27/58 20060101 G03B027/58 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2004 |
JP |
2004-087078 |
Claims
1-12. (canceled)
13. An exposure apparatus comprising: (i) a stator unit having
coils; (ii) a plurality of movable elements, each movable element
having a holder for holding a substrate and moving along a surface
of said stator unit, said stator unit comprising: (a) an exposure
region where the substrate is to be subjected to a process of
exposing the substrate; and (b) a measurement region where the
substrate is to be subjected to a process of measuring a position
of the substrate, wherein one of said movable elements is operated
for the exposure process while another of said movable elements is
operated for the measurement process, and coils of the exposure
region and coils of the measurement region are cooled
independently, based on a cooling amount corresponding to the
operation of the movable element in each region.
14. The apparatus according to claim 13, wherein (i) said stator
unit has a cooling jacket which surrounds said coils, (ii) said
cools are cooled by supplying a refrigerant into said cooling
jacket, and (iii) the refrigerant flows in a direction
perpendicular to a direction in which the exposure region and the
measurement region are arranged.
15. The apparatus according to claim 14, wherein the refrigerant
flows in different directions between the exposure region and the
measurement region.
16. The apparatus according to claim 13, wherein (i) said stator
unit has a cooling jacket surrounding the coils, (ii) the coils are
cooled by causing a refrigerant to flow into the cooling jacket,
and (iii) the refrigerant of the exposure region and the
refrigerant of the measurement region differ by at least one of a
flow rate, temperature, and medium of the refrigerant.
17. The apparatus according to claim 13, wherein said stator unit
is divided in the exposure region and the measurement region.
18. The apparatus according to claim 13, wherein said movable
elements have magnets on a surface thereof which oppose said stator
unit, said magnets serving to generated a force with respect to
said coils of said stator unit.
19. An exposure apparatus which aligns a substrate by a stage
device for driving a movable element, mounted with a substrate
thereon, by using a plane motor, said stage device comprising: (i)
a stator unit having coils; and (ii) a plurality of said movable
element which move on said stator unit, said stator unit
comprising: (a) an exposure region where the substrate is to be
subjected to a process of exposing the substrate; and (b) a
measurement region where the substrate is to be subjected to a
process of measuring a position of the substrate, wherein the coils
of said stator units of the exposure region and the coils of said
stator units of the measurement region are cooled independently by
a refrigerant, and the refrigerant flows in a direction
perpendicular to a direction in which the exposure region and the
measurement region are arrayed.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a stage device and, more
particularly, is suitably used by a stage device in an exposure
apparatus in which an alignment system and exposure system are
formed independently of each other.
BACKGROUND OF THE INVENTION
[0002] In an exposure apparatus, a structure in which an alignment
system and exposure system are formed independently of each other
and a plane motor is employed as a positioning stage is disclosed
in Japanese Patent Laid-Open No. 2001-217183. FIG. 8 is a view
showing a stage device in the exposure apparatus disclosed in
Japanese Patent Laid-Open No. 2001-217183.
[0003] Referring to FIG. 8, reference symbol PL denotes a
projection optical system; and ALG, an alignment optical system. A
stator 112 as a base has a measurement (alignment) region and
exposure region. Two movable stages (WST1 and WST2) can move in the
measurement region and exposure region independently of each other.
In this exposure system, exposure and alignment measurement can be
performed simultaneously, so that the throughput can be
improved.
[0004] The plane motor has a magnet group (not shown) arrayed on
the lower surfaces of the movable stages (WST1 and WST2) and a coil
group 98 arrayed in a matrix in the stator 112. The Lorentz force
generated by the mutual operation of the magnetic fluxes of the
magnet group and a current flowing through the coil group can move
the movable stages (WST1 and WST2) relative to the stator 112.
[0005] FIG. 7 shows the coil cooling structure of a plane motor
disclosed in Japanese Patent Laid-Open No. 2001-175434. The coil
group of the plane motor stator is sealed by a stator main body 32.
In FIG. 7, a refrigerant is supplied from 88A (88B) and discharged
from 92A (92B) to cool the coil group in the stator.
[0006] Generally, stage operation for performing alignment
measurement and stage operation for performing exposure are often
different from each other. In an exposure process, scanning must be
performed for every shot of the exposure target. Thus, the stage
moves uniformly to a certain degree through the entire region. In
alignment measurement, the movement required of the stage varies
depending on the accuracy to be obtained and a measuring method.
Therefore, usually, the energization amount for the coil group
arranged in the exposure region and that for the coil group
arranged in the measurement region are different, and naturally the
heat values of the two coil groups are expected to be
different.
[0007] For example, in the alignment measurement, assume that a
scheme that does not measure the entire wafer but measures only a
certain representative point is employed. The movement of the stage
required in the alignment measurement may be smaller than that
required in the exposure region, and the energization amount and
energization time of the coils are accordingly smaller than those
for the coils in the exposure region. Therefore, the heat amount of
the coil group in the measurement region becomes smaller than that
in the exposure region. In fine, heat generation of the coil group
in the stator largely differs between the two regions.
[0008] For this reason, in an exposure apparatus having two
independent regions, i.e., an exposure region and measurement
region, as in FIG. 8, if the coil group in the stator is cooled
collectively as in FIG. 7, the cooling efficiency is expectedly
poor. Usually, the flow rate of the refrigerant flowing through a
refrigerant pipe 89A (89B) of FIG. 7 is set such that the
temperature of the refrigerant becomes equal to or less than an
allowable temperature with respect to a coil with the largest heat
generation.
[0009] In the structure in which the coil group in the stator is
cooled collectively, if variations in coil heat generation are
large, a coil with small heat generation is cooled by an
excessively large amount of refrigerant. As a result, although a
large amount of refrigerant is supplied as a whole, the maximum
coil temperature cannot be suppressed easily.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to efficiently
remove, in a stage device having different process regions, heat
generated by driving of a movable element having an object
thereon.
[0011] In order to achieve the above object, according to the
present invention, there is provided a stage device for driving a
movable element, mounted with an object thereon, by using a plane
motor, comprising a stator unit having a coil group, and the
movable element which moves on the stator unit, the stator unit
comprising a first region where the object is to be subjected to a
first process, and a second region where the object is to be
subjected to a second process, wherein the coil group in the stator
unit is temperature-controlled independently between the first and
second regions.
[0012] According to the present invention, in a stage device having
different process regions, heat generated by driving of a movable
object mounted with an object thereon can be removed
efficiently.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGS. 1A and 1B are views showing a stage device according
to the first embodiment;
[0014] FIG. 2 is a view showing a stator unit in detail;
[0015] FIG. 3A shows a coil array in an odd-numbered layer;
[0016] FIG. 3B shows a coil array in an even-numbered layer;
[0017] FIG. 4 is a view showing an exposure apparatus;
[0018] FIG. 5 is a flowchart showing a device manufacturing
method;
[0019] FIG. 6 is a flowchart showing a wafer process in FIG. 5;
[0020] FIG. 7 is a view showing the cooling structure of a plane
motor according to a prior art; and
[0021] FIG. 8 is a view showing the structure of twin stages
according to the prior art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
First Embodiment
[0022] FIGS. 1A and 1B show a stage device according to the first
embodiment. FIG. 1A is a view of the stage device seen from above,
and FIG. 1B is a sectional view of the stage device seen from the
horizontal direction. The stage device is divided into an exposure
region and measurement region. An exposure optical system PL is
arranged in the exposure region, and a measurement optical system
ALG for alignment measurement is arranged in the measurement
region.
[0023] On stator units 3, two movable stages (WST1 and WST2) can
perform exposure operation and measurement operation in the
corresponding regions. The movable stages WST1 and WST2 can be
swapped between the exposure region and measurement region. For
example, the movable stage WST2 where wafer measurement operation
has been finished swaps regions with the movable stage WST1 where
exposure has been finished. The movable stage WST2 continuously
starts exposure operation. The movable stage WST1 transfers an
exposed wafer to a wafer transport system (not shown) and receives
a new wafer to start alignment operation. When the system is formed
to perform exposure operation and measurement operation such as
alignment simultaneously in this manner, the wafer process time as
a whole can be shortened, and the throughput can be improved.
[0024] Magnet groups (not shown) are arranged on the lower surfaces
of the plate-like top plates of the movable stages WST1 and WST2,
respectively. The stator units 3 facing the movable stages include
coil groups 4 and 5, each formed of a large number of layers of
coil arrays, and cooling jackets 6 and 7 which seal the coil groups
4 and 5. Thus, the Lorentz force generated by the interaction of
the magnet groups of the movable stages and a current supplied to
the coil groups moves the movable stages WST1 and WST2 with respect
to the stator units 3.
[0025] A refrigerant such as temperature-controlled pure water or
an inert refrigerant flows through the cooling jackets 6 and 7 to
be able to cool the coils directly. Alternatively, the coils may be
cooled by providing cooling pipes among the coils.
[0026] FIG. 2 is an enlarged view of part of the coil group 4 or 5
in the corresponding stator unit 3. As described above, the coil
group has a large number of layers of coil arrays in the vertical
direction. In FIG. 2, a coil array 11 at the first layer from the
top is a coil array that contributes to driving in an X-axis
direction and .omega.z direction (rotational direction about the
Z-axis). The coil array 11 is formed by arranging a plurality of
coils 18, having straight portions elongated in the Y-axis
direction as shown in FIG. 3A, in the X-axis direction.
[0027] Similarly, a coil array 12 at the second layer from the top
is a coil array that contributes to driving in a Y-axis direction
and the .omega.z direction. The coil array 12 is formed by
arranging a plurality of coils 19, having straight portions
elongated in the X-axis direction as shown in FIG. 3B, in the
Y-axis direction. A coil array 13 at the third layer is a coil
array that contributes to driving in a Z-axis direction and
.omega.y direction (rotational direction about the Y-axis). The
coil array 13 is formed as shown in FIG. 3A. A coil array 14 at the
fourth layer is a coil array that contributes to driving in the
Z-axis direction and an .omega.x direction (rotational direction
about the X-axis). The coil array 14 is formed as shown in FIG. 4.
The four layers of coil arrays can drive the movable stages in
6-axis directions.
[0028] The arrangement of the coil group is not limited to this. As
shown in FIG. 8, coils may be arranged in a matrix. Furthermore,
the plane motor suffices as far as its stator unit has a coil group
serving as a heat generating portion.
[0029] The respective coil arrays are supported on a base surface
plate 17 through support members 10. The gaps among the coil arrays
form refrigerant flow channels. More specifically, the upper and
lower surfaces of the coils come into contact with the circulating
refrigerant so that they can be cooled directly. When the coil
group is cooled in this manner by circulating the refrigerant in
the cooling jacket that surrounds the coil group, heat generated by
the coils is removed quickly to prevent excessive temperature rise
of the coils and temperature rise of the stator unit.
[0030] The cooling jackets 6 and 7 are provided to the exposure
region and measurement region independently of each other, and can
optimally cool the corresponding regions independently of each
other. If all the stators of a plane motor are cooled collectively
as in the prior art, the entire cooling efficiency is poor, and the
refrigerant temperature controlling unit, refrigerant circulating
unit, and the like may become bulky. When the measurement region
and exposure region where the stages move differently can be cooled
independently of each other, the respective regions can be cooled
(e.g., flow rate of the refrigerant, temperature, and the type of
the refrigerant) optimally for the movement of the stages. Then, an
increase in the cooling efficiency can be expected, and units
related to temperature control can be made compact.
[0031] This will be described in more detail. When cooling aims at
prevention of overheating of the coils, the cooling amount (the
flow rate of the refrigerant, the temperature of the refrigerant,
and the type of the refrigerant) is adjusted for a coil with the
largest heat generation. When the two regions, i.e., the
measurement region and exposure region, are to be cooled
collectively, the cooling amount is set to a value for the coil
with the largest heat generation among all the coils.
[0032] Usually, however, the stages move in the measurement region
and exposure region largely differently from each other, and
accordingly the heat generation amount of the coils is largely
different between the measurement region and exposure region. For
example, assume that the stage in the exposure region moves
actively while the stage in the measurement stage does not move
very actively so much as a stage because of wafer transfer or the
like. Then, only the coil group in the exposure region generates
heat largely, and the coil group in the measurement region rarely
generates heat.
[0033] If the two regions are to be cooled collectively, the
refrigerant in a cooling amount for the coils in the exposure
region is supplied to the entire cooling jacket, so that an
excessively large amount of refrigerant flows to the coil group in
the measurement region wastefully. For example, an excessively
large flow rate of the refrigerant is required for all the stators.
The cooling efficiency (the removing rate of heat generated by the
coils to the flow rate of the refrigerant) decreases, and the units
concerning temperature control become bulky.
[0034] In view of these situations, in FIGS. 1A and 1B, the
measurement region and exposure region can be cooled independently
of each other. More specifically, as the stages in the measurement
region and exposure region move largely differently, cooling of the
respective regions is optimized independently to increase the
cooling efficiency as a whole. Cooling optimization includes, e.g.,
a change in at least one of the flow rate of the refrigerant, the
temperature, and the type of the refrigerant between the
measurement region and exposure region.
[0035] As shown in FIGS. 1A and 1B, the flowing direction of the
refrigerant can also be changed. For example, when the flowing
direction of the refrigerant is changed between the exposure region
and measurement region, the refrigerant can be supplied into each
region from the vicinity of a coil with the largest heat
generation, so that optimal cooling can be performed.
[0036] The above example mainly aims at optimizing cooling in the
measurement region and exposure region independently. Naturally, as
a result of optimization of the cooling in each region, sometimes
the flowing direction of the refrigerant becomes the same between
the two regions, and the flow rate of the refrigerant may become
the same between the two regions. Therefore, the cooling method
(the flow rate of the refrigerant, the temperature, the type of the
refrigerant, and the like) need not be changed between the
measurement region and exposure region.
[0037] In FIGS. 1A and 1B, the stator units 3 appear to be provided
to the measurement region and exposure region independently. The
stator units themselves may be independent for the respective
regions or be integral throughout the respective regions. It
suffices as far as the interiors of the cooling jackets 6 and 7 can
be temperature-controlled independently of each other.
[0038] The background for providing the stator units 3 to the
exposure region and measurement region independently of each other
as in FIGS. 1A and 1B will be described.
[0039] In a plane motor in an exposure apparatus having independent
alignment system and exposure system, problems arise also in terms
of the fabrication and maintenance of the stators. More
specifically, the minimum size of the stator unit of the plane
motor is substantially determined by the wafer size. When a 12-inch
(300-mm) wafer is the object to be processed, the necessary stroke
of the movable stage in each of the measurement region and exposure
region is about 400 mm (distance necessary for movement through the
entire wafer region+distance necessary for the
acceleration/deceleration region of the stage). In other words,
assuming that the size of the movable stage (WST1 and WST2) is
about 400 mm, the stator unit is assumed to require a size of 700
mm (300 mm as wafer size+400 mm for stroke) or more at the
minimum.
[0040] Therefore, the size of a stator unit including the
measurement region and exposure region is at a minimum of 700 mm (X
direction in FIG. 8).times.1,400 mm (Y direction in FIG. 8). In
practice, the size of the stator unit tends to become larger due to
various factors. If the stator unit having this size is to be
fabricated as one integral unit, the necessary material may be
difficult to obtain and the degree of freedom of machining may be
limited by the limitations of the machine tool highly likely.
Accordingly, the cost may be expected to increase. That is, if a
measurement region and exposure region are provided independently
of each other, the size of the stator may increase to cause
difficulties in the manufacture.
[0041] As shown in FIGS. 1A and 1B, when the stator unit includes
separate units divided into the exposure region and measurement
region, each fabrication size becomes half. As for fabrication of
the stator units an exposure region unit and fabrication of a
measurement region unit can be fabricated simultaneously, so that
the fabrication lead time can also be decreased. From the viewpoint
of maintenance, a countermeasure need be taken only for a unit
where a trouble occurs. Thus, the maintenance need only be
performed often on a small scale.
[0042] The above description has been made by exemplifying a stage
device using a plane motor. In a stage device provided with
separate linear motors to drive respective stages for the exposure
region and measurement region as well, to temperature-control the
respective driving means independently of each other is effective
in terms of the cooling efficiency. Note that the stage device
using a plane motor is effective because the exposure region and
measurement region can be cooled independently of each other with a
simple structure and the heat generation amount of the coils is
large.
[0043] FIG. 4 shows an exposure apparatus for semiconductor device
manufacture which uses a stage device similar to that described
above as a wafer stage.
[0044] This exposure apparatus is used to manufacture devices
having fine patterns, e.g., a semiconductor device such as a
semiconductor integrated circuit, a micromachine, and a thin-film
magnetic head. Exposure light (this is a generic term for visible
light, ultraviolet light, EUV light, X-rays, an electron beam, a
charged particle beam, or the like) serving as an exposure energy
from an illumination system unit 501 through a reticle as an
original irradiates a semiconductor wafer W as a substrate through
a projection lens 503 (this is a generic term for a dioptric lens,
reflecting lens, cata-dioptric lens system, charged particle lens,
or the like) serving as a projecting system to form a desired
pattern on a substrate mounted on a wafer stage 504. As the
wavelength of the exposure light becomes short, the exposure
apparatus requires exposure in a vacuum atmosphere.
[0045] A wafer (object) as a substrate is held on a chuck mounted
on the wafer stage 504. The pattern of the reticle as the original
mounted on a reticle stage 502 is transferred onto the respective
regions on the wafer by the illumination system unit 501 in
accordance with step & repeat or step & scan. In this case,
the stage device described above is used as the wafer stage
504.
[0046] When the stage device described above is applied to an
exposure apparatus in the above manner, an exposure apparatus
requiring a decreased operation cost can be provided.
[0047] A semiconductor device manufacturing process which uses this
exposure apparatus will be described. FIG. 5 is a flowchart showing
the flow of the entire semiconductor device manufacturing process.
In step 1 (circuit design), the circuit of a semiconductor device
is designed. In step 2 (mask fabrication), a mask is fabricated on
the basis of the designed circuit pattern.
[0048] In step 3 (wafer manufacture), a wafer is manufactured using
a material such as silicon. In step 4 (wafer process) called a
preprocess, an actual circuit is formed on the wafer by the above
exposure apparatus in accordance with lithography using the above
mask and wafer. In the next step 5 (assembly) called a
post-process, a semiconductor chip is formed from the wafer
fabricated in step 4. This step includes assembly processes such as
assembly (dicing and bonding) and packaging (chip encapsulation).
In step 6 (inspection), inspections including operation check test
and durability test of the semiconductor device fabricated in step
5 are performed. A semiconductor device is finished with these
processes and shipped in step 7.
[0049] The wafer process of the above step 4 includes the following
steps (FIG. 6), i.e., an oxidation step of oxidizing the surface of
the wafer, a CVD step of forming an insulating film on the wafer
surface, an electrode formation step of forming an electrode on the
wafer by deposition, an ion implantation step of implanting ions in
the wafer, a resist process step of applying a photosensitive agent
to the wafer, an exposure step of transferring the circuit pattern
to the wafer after the resist process step by the exposure
apparatus described above, a developing step of developing the
wafer exposed in the exposure step, an etching step of removing
portions other than the resist image developed in the developing
step, and a resist removal step of removing any unnecessary resist
after etching. These steps are repeated to form multiple circuit
patterns on the wafer.
[0050] When the exposure apparatus described above is used in part
of the device manufacturing process in this manner, an,inexpensive
device can be manufactured.
[0051] While the present invention has been described with respect
to what is presently considered to be the preferred embodiments, it
is to be understood that the invention is not limited to the
disclosed embodiments. The present invention is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
CLAIM OF PRIORITY
[0052] This application claims priority from Japanese Patent
Application No. 2004-087078 filed on Mar. 24, 2004, which is hereby
incorporated by reference herein.
* * * * *