U.S. patent application number 10/453270 was filed with the patent office on 2003-10-30 for stage assembly including a reaction assembly that is connected by actuators.
Invention is credited to Binnard, Mike.
Application Number | 20030202167 10/453270 |
Document ID | / |
Family ID | 27623401 |
Filed Date | 2003-10-30 |
United States Patent
Application |
20030202167 |
Kind Code |
A1 |
Binnard, Mike |
October 30, 2003 |
Stage assembly including a reaction assembly that is connected by
actuators
Abstract
A stage assembly (10) for moving and positioning a device (26)
is provided herein. The stage assembly (10) includes a stage base
(12), a stage (14), a stage mover assembly (16), and a reaction
assembly (18). The stage mover assembly (16) moves the stage (14)
along an X axis and along a Y axis relative to the stage base (12).
The reaction assembly (18) is coupled to the stage mover assembly
(16). Uniquely, the reaction assembly (18) reduces the reaction
forces created by the stage mover assembly (16) in three degrees of
freedom that are transferred to the stage base (12). As provided
herein, the reaction assembly (18) includes a first reaction mass
(88) and a second reaction mass (90) that move independently along
the X axis, along the Y axis and about a Z axis. With this design,
stage mover assembly (16) has less influence upon the position of
the stage base (12). These features allow for more accurate
positioning of the device (26) by the stage assembly (10) and
better performance of the stage assembly (10).
Inventors: |
Binnard, Mike; (Belmont,
CA) |
Correspondence
Address: |
The Law Office of Steven G. Roeder
5560 Chelsea Avenue
La Jolla
CA
92037
US
|
Family ID: |
27623401 |
Appl. No.: |
10/453270 |
Filed: |
June 3, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10453270 |
Jun 3, 2003 |
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09713910 |
Nov 16, 2000 |
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6603531 |
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Current U.S.
Class: |
355/72 ; 310/10;
310/12.06; 355/52; 355/75 |
Current CPC
Class: |
G03F 7/70766 20130101;
G03B 27/42 20130101 |
Class at
Publication: |
355/72 ; 355/52;
355/75; 310/10; 310/12 |
International
Class: |
G03B 027/58 |
Claims
What is claimed is:
1. A stage assembly that moves a device, the stage assembly
comprising: a device table that retains the device; a stage base
that supports the device table; a mover assembly connected to the
device table, the mover assembly moving the device table and
generating reaction forces in at least two degrees of freedom; and
a reaction assembly including (i) a reaction mass assembly coupled
to the mover assembly, the reaction mass assembly reducing the
reaction forces in at least two degrees of freedom, and (ii) a
reaction mover assembly that moves the reaction mass assembly
relative to the stage base, the reaction mover assembly including a
trim mover having a first component that is secured to the reaction
mass assembly and a second component, the first component moving
relative to the second component with at least two degrees of
freedom.
2. The stage assembly of claim 1 further comprising a control
system connected to the trim mover, the control system directing
current to the trim mover to move the first component with at least
two degrees of freedom relative to the second component.
3. The stage assembly of claim 1 wherein the reaction mass assembly
includes a first reaction mass and a second reaction mass, and
wherein at least one of the reaction masses moves relative to the
stage base with at least three degrees of freedom to reduce the
reaction forces.
4. The stage assembly of claim 1 wherein the reaction mass assembly
includes a first reaction mass and a second reaction mass, wherein
the reaction assembly includes a reaction base assembly, and
wherein each reaction mass moves relative to the reaction base
assembly with at least two degrees of freedom.
5. The stage assembly of claim 4 further comprising a first Y guide
mover, a second Y guide mover, and a guide assembly which cooperate
to connect the first reaction mass to the second reaction mass.
6. The stage assembly of claim 4 further comprising a first Y guide
mover, a second Y guide mover, and a guide assembly coupled to the
device table, wherein the first Y guide mover connects the guide
assembly to the first reaction mass and the second Y guide mover
connects the guide assembly to the second reaction mass.
7. The stage assembly of claim 4 wherein the mover assembly
comprises (i) an X stage mover that moves the device table along an
X axis, the X stage mover being coupled to the first reaction mass
so that movement of the device table by the X stage mover results
in movement of the first reaction mass along the X axis relative to
the stage base, and (ii) a Y table mover that moves the device
table along a Y axis, the Y table mover being coupled to the first
reaction mass so that movement of the device table by the Y table
mover results in movement of the first reaction mass along the Y
axis relative to the stage base.
8. The stage assembly of claim 7 wherein the reaction mover
assembly adjusts the position of the first reaction mass relative
to the stage base along the X axis, and along the Y axis.
9. The stage assembly of claim 8 wherein the reaction mover
assembly adjusts the position of the second reaction mass relative
to the stage base and the first reaction mass with at least two
degrees of freedom.
10. The stage assembly of claim 8 wherein the reaction mover
assembly adjusts the position of the first reaction mass relative
to the stage base about a Z axis.
11. The stage assembly of claim 7 further comprising a guide
assembly, a first Y guide mover and a second Y guide mover which
cooperate to connect the first reaction mass to the second reaction
mass.
12. The stage assembly of claim 11 wherein the X stage mover moves
the guide assembly along the X axis and the Y table mover moves the
device table along the guide assembly.
13. The stage assembly of claim 11 wherein the reaction mover
assembly adjusts the position of the first reaction mass relative
to the reaction base assembly and the second reaction mass with at
least two degrees of freedom, and the reaction mover assembly
adjusts the position of the second reaction mass relative to the
reaction base assembly and the first reaction mass with at least
two degrees of freedom.
14. The stage assembly of claim 11 wherein the reaction mover
assembly adjusts the position of the first reaction mass relative
to the reaction base assembly and the second reaction mass with at
least three degrees of freedom, and the reaction mover assembly
adjusts the position of the second reaction mass relative to the
reaction base assembly and the first reaction mass with at least
three degrees of freedom.
15. The stage assembly of claim 4 wherein the reaction mover
assembly includes at least one planar motor.
16. The stage assembly of claim 4 wherein the reaction mover
assembly includes a first pair of planar motors that adjusts the
position of the first reaction mass.
17. The stage assembly of claim 16 wherein the reaction mover
assembly includes a second pair of planar motors that adjusts the
position of the second reaction mass.
18. The stage assembly of claim 1 wherein the first component moves
relative to the second component with at least three degrees of
freedom.
19. The stage assembly of claim 1 further comprising a control
system connected to the trim mover, the control system directing
current to the trim mover to move the first component with at least
three degrees of freedom relative to the second component.
20. The stage assembly of claim 1 wherein the trim mover moves at
least a portion of the reaction mass assembly with at least two
degrees of freedom relative to the stage base.
21. The stage assembly of claim 20 wherein the trim mover moves at
least a portion of the reaction mass assembly with at least three
degrees of freedom relative to the stage base.
22. The stage assembly of claim 1 wherein the trim mover includes a
planar motor.
23. An exposure apparatus including the stage assembly of claim
1.
24. A device manufactured with the exposure apparatus according to
claim 23.
25. A wafer on which an image has been formed by the exposure
apparatus of claim 23.
26. A stage assembly that moves a device, the stage assembly
comprising: a device table that retains the device; a mover
assembly connected to the device table, the mover assembly moving
the device table and generating reaction forces; a first reaction
mass that is coupled to the mover assembly, the first reaction mass
reducing the reaction forces; and a reaction mover assembly secured
to the first reaction mass, the reaction mover assembly including a
trim mover having a planar motor that moves the first reaction mass
with at least two degrees of freedom.
27. The stage assembly of claim 26 wherein the reaction mover
assembly includes a pair of trim movers, each trim mover including
a planar motor.
28. The stage assembly of claim 26 wherein the planar motor moves
the first reaction mass with at least three degrees of freedom.
29. The stage assembly of claim 26 wherein the reaction mover
assembly moves the first reaction mass relative to the stage
base.
30. The stage assembly of claim 26 wherein the planar motor
includes a first component that is secured to the first reaction
mass and a second component, wherein current directed to the first
component moves the first component relative to the second
component with at least two degrees of freedom.
31. The stage assembly of claim 30 wherein current directed to the
first component moves the first component relative to the second
component with at least three degrees of freedom.
32. The stage assembly of claim 26 further comprising a second
reaction mass and a reaction base assembly that supports the first
reaction mass and the second reaction mass, the reaction base
assembly being isolated from the stage base.
33. The stage assembly of claim 32 wherein the reaction mover
assembly adjusts the position of the first reaction mass relative
to the reaction base assembly and the second reaction mass with at
least two degrees of freedom, and the reaction mover assembly
adjusts the position of the second reaction mass relative to the
reaction base assembly and the first reaction mass with at least
two degrees of freedom.
34. The stage assembly of claim 32 wherein the reaction mover
assembly adjusts the position of the first reaction mass relative
to the reaction base assembly and the second reaction mass with at
least three degrees of freedom, and the reaction mover assembly
adjusts the position of the second reaction mass relative to the
reaction base assembly and the first reaction mass with at least
three degrees of freedom.
35. A method for making a stage assembly that moves a device, the
method comprising the steps of: providing a device table that
retains the device; connecting a mover assembly to the device
table, the mover assembly moving the device table with at least two
degrees of freedom and generating reaction forces in at least two
degrees of freedom; and coupling a first reaction mass and a second
reaction mass to the mover assembly, each of the reaction masses
moves with at least two degrees of freedom to reduce the reaction
forces in at least two degrees of freedom, wherein the first
reaction mass moves with at least two degrees of freedom relative
to the second reaction mass.
36. The method of claim 35 wherein the step of coupling the first
reaction mass and the second reaction mass includes the step of
providing a guide assembly, a first Y guide mover that connects the
guide assembly to the first reaction mass and a second Y guide
mover that connects the guide assembly to the second reaction
mass.
37. The method of claim 35 wherein the first reaction mass moves
with at least three degrees of freedom relative the second reaction
mass.
38. The method of claim 35 including the step of supporting the
device table with a stage base, wherein the first reaction mass and
the second reaction mass move relative to the stage base with at
least two degrees of freedom.
39. The method of claim 35 including the step of connecting a
reaction mover assembly to the first reaction mass and the second
reaction mass, the reaction mover assembly independently adjusting
the position of the reaction masses relative to a reaction base
assembly along an axis.
40. The method of claim 35 including the step of connecting a
reaction mover assembly to the first reaction mass and the second
reaction mass, the reaction mover assembly independently adjusting
the position of each of the reaction masses relative with at least
two degrees of freedom.
41. The method of claim 35 including the step of connecting a
reaction mover assembly to the first reaction mass and the second
reaction mass, the reaction mover assembly independently adjusting
the position of each of the reaction masses with at least three
degrees of freedom.
42. The method of claim 41 wherein the step of connecting a
reaction mover assembly includes the step of providing a first
planar motor that moves the first reaction mass and a second planar
motor that moves the second reaction mass.
43. A method for making an exposure apparatus that forms an image
on a wafer, the method comprising the steps of: providing an
irradiation apparatus that irradiates the wafer with radiation to
form the image on the wafer; and providing the stage assembly made
by the method of claim 35.
44. A method of making a wafer utilizing the exposure apparatus
made by the method of claim 43.
45. A method of making a device including at least the exposure
process; wherein the exposure process utilizes the exposure
apparatus made by the method of claim 43.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 09/713,910 filed on Nov. 16, 2000, which is currently pending.
The contents of U.S. application Ser. No. 09/713,910 are
incorporated herein by reference.
[0002] As far as permitted, the disclosures of (i) U.S. patent
application Ser. No. 09/714,598, entitled "A SYSTEM AND METHOD FOR
RESETTING A REACTION MASS ASSEMBLY OF A STAGE ASSEMBLY," filed on
Nov. 16, 2000, (ii) U.S. patent application Ser. No. 09/714,747,
entitled, "STAGE ASSEMBLY INCLUDING A REACTION MASS ASSEMBLY,"
filed on Nov. 16, 2000, and (iii) U.S. patent application Ser. No.
09/713,911, entitled "STAGE ASSEMBLY INCLUDING A REACTION
ASSEMBLY," filed on Nov. 16, 2000, are incorporated herein by
reference.
FIELD OF THE INVENTION
[0003] The present invention is directed to a stage assembly for
moving a device. More specifically, the present invention is
directed to a stage assembly including a reaction assembly that is
connected by actuators for an exposure apparatus.
BACKGROUND
[0004] Exposure apparatuses are commonly used to transfer images
from a reticle onto a semiconductor wafer during semiconductor
processing. A typical exposure apparatus includes an illumination
source, a reticle stage assembly that retains a reticle, a lens
assembly and a wafer stage assembly that retains a semiconductor
wafer. The reticle stage assembly and the wafer stage assembly are
supported above a ground with an apparatus frame.
[0005] Typically, the wafer stage assembly includes a wafer stage
base, a wafer stage that retains the wafer, and a wafer stage mover
assembly that precisely positions the wafer stage and the wafer.
Somewhat similarly, the reticle stage assembly includes a reticle
stage base, a reticle stage that retains the reticle, and a reticle
stage mover assembly that precisely positions the reticle stage and
the reticle. The size of the images transferred onto the wafer from
the reticle is extremely small. Accordingly, the precise relative
positioning of the wafer and the reticle is critical to the
manufacturing of high density, semiconductor wafers.
[0006] Unfortunately, the wafer stage mover assembly generates
reaction forces that can vibrate the wafer stage base and the
apparatus frame. The vibration influences the position of the wafer
stage base, the wafer stage, and the wafer. As a result thereof,
the vibration can cause an alignment error between the reticle and
the wafer. This reduces the accuracy of positioning of the wafer
relative to the reticle and degrades the accuracy of the exposure
apparatus.
[0007] In light of the above, one object of the present invention
is to provide a stage assembly that precisely positions a device.
Another object is to provide a stage assembly that minimizes the
influence of the reaction forces of the stage mover assembly upon
the position of the stage, the stage base, and the apparatus frame.
Still another object is to provide a stage assembly having an
improved reaction assembly. Yet another object is to provide an
exposure apparatus capable of manufacturing precision devices such
as high density, semiconductor wafers.
SUMMARY
[0008] The present invention is directed to a stage assembly for
moving a device relative to a stage base that satisfies these
needs. The stage assembly includes a stage, a stage mover assembly,
and a reaction assembly. The stage retains the device. The stage
mover assembly is connected to the stage and moves the stage
relative to the stage base with at least two degrees of freedom.
The reaction assembly is coupled to the stage mover assembly.
[0009] Uniquely, as provided herein, the reaction assembly reduces
the reaction forces created by the stage mover assembly in at least
two degrees of freedom that are transferred to the stage base. As a
result thereof, the stage assembly can more accurately position the
device. Further, the stage assembly can be used in an exposure
apparatus to manufacture high density, high quality semiconductor
wafers.
[0010] As provided herein, the stage mover assembly can include one
or more X stage movers, one or more Y guide movers and one or more
Y table movers that are coupled to the reaction assembly. The X
stage movers move the stage along an X axis, and about a Z axis,
while the Y table movers move the stage along a Y axis. The stage
mover assembly generates reaction forces in at least two degrees of
freedom.
[0011] In the embodiments provided herein, the reaction assembly
includes a first reaction mass, a second reaction mass and a
reaction base assembly. The reaction masses move relative to the
reaction base assembly with at least two degrees of freedom and
more preferably, three degrees of freedom. More specifically, the
reaction masses independently move along an X axis, along a Y axis,
and about a Z axis relative to the reaction base assembly.
[0012] Additionally, the stage assembly includes a guide assembly
and a pair of Y guide movers that connect the first reaction mass
to the second reaction mass.
[0013] Preferably, the reaction assembly also includes a reaction
mover assembly that adjusts and corrects the position of the
reaction masses relative to the reaction base assembly. As provided
herein, the reaction mover assembly can independently adjust the
position of the reaction masses relative to the reaction base
assembly in one degree of freedom and more preferably in three
degrees of freedom. For example, the reaction mover assembly can
independently move the reaction masses along the X axis, along the
Y axis, and about the Z axis relative to the reaction base
assembly.
[0014] The present invention is also directed to a method for
making a stage assembly, a method for making an exposure apparatus,
a method for making a device and a method for manufacturing a
wafer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The novel features of this invention, as well as the
invention itself, both as to its structure and its operation, will
be best understood from the accompanying drawings, taken in
conjunction with the accompanying description, in which similar
reference characters refer to similar parts, and in which:
[0016] FIG. 1 is a perspective view of a stage assembly having
features of the present invention;
[0017] FIG. 2 is side view of the stage assembly of FIG. 1;
[0018] FIG. 3 is a top, exploded perspective view of the stage
assembly of FIG. 1;
[0019] FIG. 4 is a bottom, exploded perspective view of the stage
assembly of FIG. 1;
[0020] FIG. 5 is a perspective view of a pair of actuators having
features of the present invention;
[0021] FIG. 6 is same view as FIG. 1, except FIG. 6 includes
symbols used to describe the features of a control system;
[0022] FIG. 7 is a perspective view of another embodiment of a
stage assembly having features of the present invention;
[0023] FIG. 8 is a schematic illustration of an exposure apparatus
having features of the present invention;
[0024] FIG. 9 is a flow chart that outlines a process for
manufacturing a device in accordance with the present invention;
and
[0025] FIG. 10 is a flow chart that outlines device processing in
more detail.
DESCRIPTION
[0026] Referring initially to FIGS. 1-4, a stage assembly 10 having
features of the present invention, includes a stage base 12, at
least one stage 14, a stage mover assembly 16, a reaction assembly
18, a measurement system 20 (only a portion is illustrated in FIGS.
1, 3 and 4), and a control system 22. The stage assembly 10 is
positioned above a mounting base 24 (illustrated in FIG. 8). As an
overview, the stage mover assembly 16 precisely moves the stage 14
relative to the stage base 12. Further, the reaction assembly 18
reduces and minimizes the amount of reaction forces from the stage
mover assembly 16 that are transferred to the stage base 12 and the
mounting base 24.
[0027] The stage assembly 10 is particularly useful for precisely
positioning a device 26 during a manufacturing and/or an inspection
process. The type of device 26 positioned and moved by the stage
assembly 10 can be varied. For example, the device 26 can be a
semiconductor wafer 28 and the stage assembly 10 can be used as
part of an exposure apparatus 30 (illustrated in FIG. 8) for
precisely positioning the semiconductor wafer 28 during
manufacturing of the semiconductor wafer 28. Alternately, for
example, the stage assembly 10 can be used to move other types of
devices during manufacturing and/or inspection, to move a device
under an electron microscope (not shown), or to move a device
during a precision measurement operation (not shown).
[0028] Some of the Figures provided herein include a coordinate
system that designates an X axis, a Y axis, and a Z axis. It should
be understood that the coordinate system is merely for reference
and can be varied. For example, the X axis can be switched with the
Y axis and/or the stage assembly 10 can be rotated.
[0029] In each embodiment illustrated herein, the stage 14 is moved
relative to the stage base 12 along the X axis, along the Y axis,
and about the Z axis (collectively "the planar degrees of
freedom"). More specifically, the stage mover assembly 16 moves and
positions the stage 14 along the X axis, along the Y axis, and
about the Z axis under the control of the control system 22.
Additionally, the stage assembly 10 could be designed to include
two or more stages that are moved independently as illustrated in
FIG. 7.
[0030] Importantly, the reaction assembly 18 reduces and minimizes
the amount of reaction force and disturbance from the stage mover
assembly 16 that are transferred to the stage base 12 and the
mounting base 24. This improves the positioning performance of the
stage assembly 10. Further, for an exposure apparatus 30, this
allows for more accurate positioning of the semiconductor wafer 28
relative to a reticle 32 (illustrated in FIG. 8).
[0031] As an overview, in the embodiments provided herein, the
reaction assembly 18 includes a reaction mass assembly 34, a
reaction base assembly 36 and a reaction mover assembly 38. The
reaction mass assembly 34 moves relative to the reaction base
assembly 36 and the stage base 12 with at least two degrees of
freedom and more preferably, three degrees of freedom.
[0032] In a preferred embodiment of the present invention, the
reaction mass assembly 34 is free to move along the X axis, along
the Y axis, and about the Z axis relative to the reaction base
assembly 36 and the stage base 12. In this embodiment, when the
stage mover assembly 16 applies a force to the stage 14 along the X
axis, the Y axis, and/or about the Z axis, an equal and opposite
force is applied to the reaction mass assembly 34. Further, the
control system 22 controls the reaction mover assembly 38 to
correct the position of the reaction mass assembly 34 along the X
axis, along the Y axis, and about the Z axis.
[0033] The stage base 12 supports a portion of the stage assembly
10 above the mounting base 24. The design of the stage base 12 can
be varied to suit the design requirements of the stage assembly 10.
In the embodiment illustrated in FIGS. 1-4, the stage base 12 is
generally rectangular shaped and includes a planar base top 40A
(sometimes referred to as a guide face), an opposed base bottom
40B, and four base sides 42.
[0034] Preferably, referring to FIG. 8, the stage base 12 is
secured with resilient base isolators 44 and a base frame 46 to the
mounting base 24. The base isolators 44 reduce the effect of
vibration of the base frame 46 causing vibration on the stage base
12. Typically, three or four spaced apart base isolators 44 are
utilized. Each base isolator 44 can include a pneumatic cylinder
(not shown) and an actuator (not shown). Suitable base isolators 44
are sold by Technical Manufacturing Corporation, located in
Peabody, Mass., or Newport Corporation located in Irvine,
Calif.
[0035] The stage 14 retains the device 26. The stage 14 is
precisely moved by the stage mover assembly 16 to precisely
position the device 26. The design of each stage 14 can be varied
to suit the design requirements of the stage assembly 10. In the
embodiment illustrated in the Figures, the stage 14 includes a
device table 48, a guide assembly 50, a portion of the stage mover
assembly 16, and a portion of the measurement system 20.
[0036] The design and movement of the device table 48 can be
varied. In the embodiment illustrated in FIGS. 1-4, the device
table 48 moves relative to the guide assembly 50 along the Y axis.
Further, the device table 48 includes: (i) an upper table component
52, (ii) a lower table component 54 positioned below the upper
table component 52, and (iii) a table mover assembly 56
(illustrated in FIG. 2). In this design, the table mover assembly
56 moves the upper table component 52 relative to the lower table
component 54.
[0037] The upper table component 52 is generally rectangular
shaped. The upper table component 52 includes a device holder (not
shown) and a portion of the measurement system 20. The device
holder retains the device 26 during movement. The device holder can
be a vacuum chuck, an electrostatic chuck, or some other type of
clamp.
[0038] The lower table component 54 is somewhat rectangular tube
shaped and includes a guide opening 62. The guide opening 62 is
sized and shaped to receive a portion of the guide assembly 50. In
the embodiment illustrated in the Figures, the guide opening 62 is
generally rectangular shaped and extends longitudinally along the
lower table component 54.
[0039] In the embodiments provided herein, the device table 48 is
maintained above the stage base 12 with a vacuum preload type fluid
bearing. More specifically, the bottom of the device table 48
includes a plurality of spaced apart fluid outlets (not shown), and
a plurality of spaced apart fluid inlets (not shown). Pressurized
fluid (not shown) is released from the fluid outlets towards the
stage base 12 and a vacuum is pulled in the fluid inlets to create
a vacuum preload type, fluid bearing between the lower table
component 54 and the stage base 12. The vacuum preload type fluid
bearing allows for motion of the device table 48 relative to the
stage base 12 along the X axis, along the Y axis and about the Z
axis relative to the stage base 12.
[0040] Further, the device table 48 is maintained apart from the
guide assembly 50 with a fluid bearing. More specifically, in this
embodiment, pressurized fluid (not shown) is released from fluid
outlets positioned around the guide opening 62 towards the guide
assembly 50 to create a fluid bearing between the lower table
component 54 and the guide assembly 50. The fluid bearing allows
for motion of the device table 48 relative to the guide assembly 50
along the Y axis. Further, the fluid bearing inhibits motion of the
device table 48 relative to the guide assembly 50 along the X axis
and about the Z axis.
[0041] Alternately, the device table 48 can be supported spaced
apart from the stage base 12 and the guide assembly 50 in other
ways. For example, a magnetic type bearing (not shown) or a roller
bearing type assembly (not shown) could be utilized.
[0042] The table mover assembly 56 adjusts the position of the
upper table component 52 relative to the lower table component 54
and the stage base 12. The design of the table mover assembly 56
can be varied to suit the design requirements to the stage assembly
10. For example, the table mover assembly 56 can adjust the
position of the upper table component 52 and the device holder
relative to the lower table component 54 with six degrees of
freedom. Alternately, for example, the table mover assembly 56 can
be designed to move the upper table component 52 relative to the
lower table component 54 with only three degrees of freedom. The
table mover assembly 56 can include one or more rotary motors,
voice coil motors, linear motors, electromagnetic actuators, or
other type of actuators. Still alternately, the upper table
component 52 could be fixed to the lower table component 54
[0043] The guide assembly 50 is used to move the device table 48
along the X axis and about the Z axis and guide the movement of the
device table 48 along the Y axis. Further, the guide assembly 50
functions as a reaction mass along the Y axis. The design of the
guide assembly 50 can be varied to suit the design requirements of
the stage assembly 10. In the embodiment illustrated in FIGS. 1-4,
the guide assembly 50 is generally rectangular shaped and includes
a first guide end 68, and a spaced apart second guide end 70.
[0044] The guide assembly 50 also includes a pair of spaced apart,
guide fluid pads 72. In this embodiment, each of the guide fluid
pads 72 includes a plurality of spaced apart fluid outlets (not
shown), and a plurality of spaced apart fluid inlets (not shown).
Pressurized fluid (not shown) is released from the fluid outlets
towards the stage base 12 and a vacuum is pulled in the fluid
inlets to create a vacuum preload type, fluid bearing between each
of the guide fluid pads 72 and the stage base 12. The vacuum
preload type, fluid bearing maintains the guide assembly 50 spaced
apart along the Z axis relative to the stage base 12 and allows for
motion of the guide assembly 50 along the X axis, along the Y axis,
and about the Z axis relative to the stage base 12.
[0045] Additionally, the guide assembly 50 includes a first bracket
73A that extends away from the first guide end 68 and a second
bracket 73B that extends away from the second guide end 70. The
brackets 73A, 73B secure a portion of the stage mover assembly 16
to the guide assembly 50. In the embodiment illustrated in the
Figures, each of the brackets 73A, 73B is a generally "C" channel
shaped.
[0046] The components of the stage 14 can be made of a number of
materials including ceramic, such as alumina or silicon carbide;
metals such as aluminum; composite materials; or plastic.
[0047] The stage mover assembly 16 controls and moves the stage 14
relative to the stage base 12. When the stage mover assembly 16
applies a force to move the stage 14 along the X axis, along the Y
axis, and/or about the Z axis, an equal and opposite reaction force
is applied to the reaction assembly 18.
[0048] The design of the stage mover assembly 16 and the movement
of the stage 14 can be varied to suit the movement requirements of
the stage assembly 10. In the embodiment illustrated in FIGS. 1-4,
the stage mover assembly 16 moves the stage 14 with a relatively
large displacement along the X axis, a relatively large
displacement along the Y axis, and a limited displacement about the
Z axis (theta Z) relative to the stage base 12. In this embodiment,
the stage mover assembly 16 includes a first X stage mover 76A, a
second X stage mover 76B, a first Y guide mover 78A, a second Y
guide mover 78B and a Y table mover 80. The X stage movers 76A, 76B
move the stage 14 along the X axis and about the Z axis. The Y
guide movers 78A, 78B move the guide assembly 50 along the Y axis
and the Y table mover 80 moves the device table 48 along the Y
axis. More specifically, in this embodiment, (i) the X stage movers
76A, 76B move the guide assembly 50 with a relatively large
displacement along the X axis and with a limited range of motion
about the Z axis (theta Z), (ii) the Y guide movers 78A, 78B move
the guide assembly 50 with a small displacement along the Y axis,
and (iii) the Y table mover 80 moves the device table 48 with a
relatively large displacement along the Y axis.
[0049] The design of each mover 76A, 76B, 78A, 78B, 80 can be
varied to suit the movement requirements of the stage assembly 10.
As provided herein, each of the movers 76A, 76B, 78A, 78B, 80
includes a reaction component 82 and an adjacent moving component
84 that interacts with the reaction component 82. In the
embodiments provided herein, each of the Y guide movers 78A, 78B
includes an opposed pair of attraction type actuators 86. Further,
in the embodiments provided herein, for the X stage movers 76A, 76B
and the Y table mover 80, one of the components 82, 84 includes one
or more magnet arrays (not shown) and the other component 82, 84
includes one or more conductor arrays (not shown).
[0050] Each magnet array includes one or more magnets. The design
of each magnet array and the number of magnets in each magnet array
can be varied to suit the design requirements of the movers 76A,
76B, 80. Each magnet can be made of a permanent magnetic material
such as NdFeB.
[0051] Each conductor array includes one or more conductors. The
design of each conductor array and the number of conductors in each
conductor array is varied to suit the design requirements of the
movers 76A, 76B, 80. Each conductor can be made of metal such as
copper or any substance or material responsive to electrical
current and capable of creating a magnetic field such as
superconductors.
[0052] Electrical current (not shown) is supplied to the conductors
in each conductor array by the control system 22. For each mover
76A, 76B, 80, the electrical current in the conductors interacts
with the magnetic field(s) generated by the one or more of the
magnets in the magnet array. This causes a force (Lorentz type
force) between the conductors and the magnets that can be used to
move the stage 14 relative to the stage base 12.
[0053] Specifically, the reaction component 82 and the moving
component 84 of each X stage mover 76A, 76B interact to selectively
move the stage 14 along the X axis and about the Z axis relative to
the stage base 12. In the embodiment illustrated herein, each X
stage mover 76A, 76B is a commutated, linear motor. The reaction
component 82 for the first X stage mover 76A is secured to a first
reaction mass 88 of the reaction assembly 18 while the moving
component 84 of the first X stage mover 76A is secured to the first
bracket 73A of the guide assembly 50. Similarly, the reaction
component 82 for the second X stage mover 76B is secured to a
second reaction mass 90 of the reaction assembly 18 while the
moving component 84 of the second X stage mover 76B is secured to
the second bracket 73B of the guide assembly 50.
[0054] In this embodiment, the reaction component 82 of each X
stage mover 76A, 76B includes a pair of spaced apart magnet arrays
while the moving component 84 of each X stage mover 76A, 76B
includes a conductor array. Alternately, for example, the reaction
component 82 can include a conductor array while the moving
component 84 can include a pair of spaced apart magnet arrays.
[0055] The required stroke of the X stage movers 76A, 76B along the
X axis will vary according to desired use of the stage assembly 10.
For an exposure apparatus 30, generally, the stroke of the X stage
movers 76A, 76B for moving the semiconductor wafer 28 is between
approximately two hundred (200) millimeters and one thousand (1000)
millimeters.
[0056] The X stage movers 76A, 76B also make relatively slight
adjustments to position of the stage 14 about the Z axis. In order
to make the adjustments about the Z axis, the moving component 84
of one of the X stage movers 76A, 76B is moved relative to the
moving component 84 of the other X stage mover 76A, 76B. With this
design, the X stage movers 76A, 76B generate torque about the Z
axis. A gap (not shown) exists between the reaction component 82
and the moving component 84 of each X stage mover 76A, 76B to allow
for slight movement of the stage 14 about the Z axis. Typically,
the gap is between approximately one millimeter and five
millimeters. However, depending upon the design of the particular
mover, a larger or smaller gap may be utilized.
[0057] The Y guide movers 78A, 78B selectively move the guide
assembly 50 along the Y axis relative to the stage base 12.
Further, the Y guide movers 78A, 78B transfer reaction forces from
the Y table mover 80 to the reaction masses 88, 90. Stated another
way, the first Y guide mover 78A connects the guide assembly 50 to
the first reaction mass 88 along the Y axis and the second Y guide
mover 78B connects the guide assembly 50 to the second reaction
mass 90. Importantly, the Y guide movers 78A, 78B and the guide
assembly 50 cooperate to mechanically connect the first reaction
mass 88 with the second reaction mass 90. As a result thereof, the
present invention can be used to reduce the reaction forces created
by the stage mover assembly 16 in at least three degrees of
freedom. Further, as a result of this design, the Y guide movers
78A, 78B, the guide assembly 50 and the reaction masses 88, 90 are
connected and coupled along the Y axis.
[0058] In the embodiment illustrated herein, each of the Y guide
movers 78A, 78B include a plurality of opposed pairs of the
attraction only type actuators 86. FIG. 5 illustrates a perspective
view of a preferred pair of attraction type actuators 86. More
specifically, FIG. 5 illustrates a perspective view of a pair of
spaced E/I core type electromagnetic actuators. Each E/I core
actuator includes an I shaped core 92 and a combination 94 that
includes an E shaped core 96 and a tubular conductor 98. The E core
96 and the I core 92 are each made of a magnetic material such as
iron, silicon steel, or Ni--Fe steel. The conductor 98 is
positioned around the center bar of the E core 96.
[0059] In FIGS. 1-4, each of the Y guide movers 78A, 78B includes
(i) a plurality of opposed pairs of the combination 94 of the E
core 96 and conductor 98 (the E core and conductor not specifically
illustrated in FIGS. 1-4) and (ii) a row of I cores 92. For the
first Y guide mover 78A, the opposed pairs of the combination 94
are secured to the first bracket 73A and the row of I cores 92 are
secured to the first reaction mass 88. For the second Y guide mover
78B, the opposed pairs of the combination 94 are secured to the
second bracket 73B and the row of I cores 92 are secured to the
second reaction mass 90. In this embodiment, for each Y guide mover
78A, 78B, the combinations 94 are considered the moving component
84 and the row of I cores 92 is considered the reaction component
82.
[0060] The Y table mover 80 moves the stage 14 with a relatively
large displacement along the Y axis relative to the stage base 12.
More specifically, the reaction component 82 (illustrated in
phantom in FIG. 3) and the moving component 84 (illustrated in
FIGS. 3 and 4) of the Y table mover 80 interact to selectively move
the device table 48 along the Y axis relative to the guide assembly
50. In the embodiment illustrated herein, the Y table mover 80 is a
commutated, linear motor. The reaction component 82 for the Y table
mover 80 is secured to the guide assembly 50, and the moving
component 84 is secured to the device table 48, within the guide
opening 62. In this embodiment, the reaction component 82 of the Y
table mover 80 includes a conductor array and the moving component
84 of the Y table mover 80 includes a magnet array. Alternately,
for example, the reaction component 82 of the Y table mover 80
could include a magnet array while the moving component 84 of the Y
table mover 80 could include a conductor array.
[0061] With this design, the Y table mover 80 makes relatively
large displacement adjustments to the position of the device table
48 along the Y axis. The required stroke of the Y table mover 80
along the Y axis will vary according to desired use of the stage
assembly 10. For an exposure apparatus 30, generally, the stroke of
the Y table mover 80 for moving the semiconductor wafer 28 is
between approximately one hundred (100) millimeters and six hundred
(600) millimeters.
[0062] Preferably, the movers 76A, 76B, 78A, 78B, 80 are positioned
to push through a center of gravity of the device table 48. In the
embodiment illustrated herein, the X stage movers 76A, 76B, the Y
guide movers 78A, 78B, the Y table mover 80, and the center of
gravity of the guide assembly 50 are positioned at approximately
the same height along the Z axis as the center of gravity of the
device table 48.
[0063] The reaction assembly 18 reduces and minimizes the influence
of the reaction forces from the stage mover assembly 16 on the
position of the stage base 12 and the mounting base 24. The design
of the reaction assembly 18 can be varied to suit the design
requirements of the stage assembly 10. As provided above, the
reaction assembly 18 includes the reaction mass assembly 34, the
reaction base assembly 36 and the reaction mover assembly 38. As
provided above, the reaction component 82 of each X stage mover
76A, 76B and each Y guide mover 78A, 78B is coupled to the reaction
mass assembly 34. With this design, the reaction forces generated
by all of the movers 76A, 76B, 78A, 78B, 80 are transferred to the
reaction mass assembly 34.
[0064] As an overview, through the principle of conservation of
momentum, movement of the stage 14 with the X stage movers 76A, 76B
along the X axis in one direction, generates an equal but opposite
X reaction force that moves the reaction mass assembly 34 in the
opposite direction along the X axis. Movement of the device table
48 and/or the guide assembly 50 with the Y movers 78A, 78B, 80
along the Y axis in one direction, generates an equal but opposite
Y reaction force that moves the reaction mass assembly 34 in the
opposite direction along the Y axis. Additionally, movement of the
stage 14 with the movers 76A, 76B, 78A, 78B, 80 can generate a
theta Z reaction force (torque) about the Z axis.
[0065] The reaction mass assembly 34 includes the first reaction
mass 88 and the second reaction mass 90. As provided herein, the
reaction masses 88, 90 are free to independently move along the X
axis, along the Y axis and about the Z axis to reduce the reaction
forces that are transferred to the stage base 12. Thus, the
reaction assembly 18 reduces and minimizes the influence of the
reaction forces from the stage mover assembly 16 on the position of
the stage base 12 and the mounting base 24. This inhibits the
reaction forces from the stage mover assembly 16 from influencing
the position of the stage base 12 and the device table 48.
[0066] The design of the reaction masses 88, 90 can be varied to
suit the design requirements of the reaction assembly 18.
Preferably, the ratio of the mass of the reaction masses 88, 90 to
the mass of the stage 14 is relatively high. This will minimize the
movement of the reaction masses 88, 90 and minimize the required
travel of the reaction mover assembly 38. A suitable ratio of the
mass of the reaction masses 88, 90 to the mass of the stage 14 is
between approximately 2:1 and 10:1. A larger mass ratio is better,
but is limited by the physical size of the reaction assembly
18.
[0067] In the embodiment illustrated in the Figures, each of the
reaction masses 88, 90 is somewhat "U" shaped and includes a mass
channel 104A, a mass bottom 104B, a mass outer wall 104C, and a
mass inner wall 104D. In this embodiment, the reaction component 82
of the first X stage mover 76A is secured to and positioned within
the mass channel 104A of the first X reaction mass 88 and the
reaction component 82 of the first Y guide mover 78A is secured to
mass inner wall 104D of the first X reaction mass 88. Similarly,
the reaction component 82 of the second X stage mover 76B is
secured to and positioned within the mass channel 104A of the
second X reaction mass 90 and the reaction component 82 of the
second Y guide mover 78B is secured to mass inner wall 104D of the
second X reaction mass 90.
[0068] In this embodiment, the reaction masses 88, 90 are
maintained above the reaction base assembly 36 with a vacuum
preload type fluid bearing. More specifically, in this embodiment,
each of the reaction masses 88, 90 include a plurality of spaced
apart fluid outlets (not shown), and a plurality of spaced apart
fluid inlets (not shown). Pressurized fluid (not shown) is released
from the fluid outlets towards the reaction base assembly 36 and a
vacuum is pulled in the fluid inlets to create a vacuum preload
type, fluid bearing between the reaction masses 88, 90 and the
reaction base assembly 36. The vacuum preload type fluid bearing
maintains the reaction masses 88, 90 spaced apart along the Z axis,
relative to the reaction base assembly 36. Further, the vacuum
preload type fluid bearing allows for motion of the reaction masses
88, 90 along the X axis, along the Y axis and about the Z axis
relative to the reaction base assembly 36.
[0069] Alternately, the reaction masses 88, 90 can be supported
spaced apart from the reaction base assembly 36 in other ways. For
example, a magnetic type bearing (not shown) or a roller type
bearing (not shown) could be utilized that allows for motion of the
reaction masses 88, 90 relative to the reaction base assembly
36.
[0070] The reaction base assembly 36 supports each of the reaction
masses 88, 90 and allows for independent movement of each of the
reaction masses 88, 90. The design of the reaction base assembly 36
can be varied. In the embodiment illustrated in the Figures, the
reaction base assembly 36 includes (i) a first mass guide 100 for
supporting movement of the first reaction mass 88 and (ii) a second
mass guide 102 for supporting movement of the second reaction mass
90. In the embodiment illustrated in the Figures, each of the mass
guides 100, 102 is substantially flat plate shaped.
[0071] As illustrated in FIG. 8, it should be noted that (i) the
first mass guide 100 is supported above the mounting base 24 with a
first mass frame 106 and (ii) the second mass guide 102 is
supported above the mounting base 24 with a second mass frame 108.
With this design each of the mass guides 100, 102 is independently
secured to the mounting base 24. Further, the mass guides 100, 102
are isolated from the stage base 12.
[0072] Preferably, (i) the first mass guide 100 is secured with the
first mass frame 106 directly to the mounting base 24, and (ii) the
second mass guide 102 is secured with the second mass frame 108
directly to the mounting base 24. Alternately, the first mass guide
100 and the second mass guide 102 can be connected together and can
be secured to the mounting base 24 with an isolation system (not
shown). Sill alternately, as illustrated in FIG. 8, (i) the first
mass guide 100 is secured to the first mass frame 106 with a
plurality of resilient first guide isolators 110 and (ii) the
second mass guide 102 is secured to the second mass frame 108 with
a plurality of resilient second guide isolators 112. The guide
isolators 110, 112 reduce the effect of vibration of the mounting
base 24 causing vibration on the mass guides 100, 102. Each of the
guide isolators 110, 112 can include a pneumatic cylinder (not
shown) and an actuator (not shown). Suitable guide isolators 110,
112 are sold by Technical Manufacturing Corporation, located in
Peabody, Mass., or Newport Corporation located in Irvine,
Calif.
[0073] Alternately, for example, the reaction mass guides 100, 102
could be secured to the stage base 12.
[0074] The reaction mover assembly 38 independently moves the
reaction masses 88, 90 to correct the position of the reaction
masses 88, 90 to compensate for external disturbances and/or to
reposition the reaction masses 88, 90 for maximum stroke in the
future. Preferably, the reaction mover assembly 38 is able to
independently move each of the reaction masses 88, 90 along the X
axis, along the Y axis and about the Z axis. The reaction mover
assembly 38 can include one or more planar motors, rotary motors,
voice coil motors, linear motors, electromagnetic actuators, and/or
force actuators.
[0075] In the embodiment illustrated in the Figures, the reaction
mover assembly 38 includes (i) a front first trim mover 114A and a
rear first trim mover 114B that collectively move the first
reaction mass 88 along the X axis, along the Y axis and about the Z
axis, and (ii) a front second trim mover 116A and a rear second
trim mover 116B that collectively move the second reaction mass 90
along the X axis, along the Y axis and about the Z axis. In this
embodiment, each of the trim movers 114A, 114B, 116A, 116B includes
a first component 118, and an adjacent second component 120
(illustrated in phantom in FIGS. 2 and 3).
[0076] Specifically, the first component 118 and the second
component 120 for each of the first trim movers 114A, 114B interact
to selectively move the first reaction mass 88 along the X axis,
along the Y axis and about the Z axis relative to the first mass
guide 100. In the embodiments provided herein, each of the first
trim movers 114A, 114B is commonly referred to as a planar electric
motor. In the design provided herein, for each of the planar
electric motors, the first component 118 moves relative to the
second component 120 along the X axis, along the Y axis and about
the Z axis. For the front first trim mover 114A, the first
component 118 is secured to the front bottom of the first reaction
mass 88, while the second component 120 is positioned within the
first mass guide 100. For the rear first trim mover 114B, the first
component 118 is secured to the rear bottom of the first reaction
mass 88, while the second component 120 is positioned within the
first mass guide 100.
[0077] Similarly, the first component 118 and the second component
120 for each of the second trim movers 116A, 116B interact to
selectively move the second reaction mass 90 along the X axis,
along the Y axis and about the Z axis relative to the second mass
guide 102. In the embodiments provided herein, each of the second
trim movers 116A, 116B is commonly referred to as a planar electric
motor. In the design provided herein, for each of the planar
electric motors, the first component 118 moves relative to the
second component 120 along the X axis, along the Y axis and about
the Z axis. For the front second trim mover 116A, the first
component 118 is secured to the front bottom of the second reaction
mass 90, while the second component 120 is positioned within the
second mass guide 102. For the rear second trim mover 116B, the
first component 118 is secured to the rear bottom of the second
reaction mass 90, while the second component 120 is positioned
within the second mass guide 102.
[0078] In the embodiments provided herein, one of the components
118, 120 of each trim mover 114A, 114B, 116A, 116B includes one or
more planar magnet arrays (not shown) and the other component 118,
120 of each trim mover 114A, 114B, 116A, 116B includes one or more
planar conductor arrays (not shown). Each magnet array includes a
plurality of spaced apart magnets and each conductor array includes
a plurality of spaced apart conductors. The size and shape of each
conductor array and the magnet array and the components of the
conductor array and the magnet array can be varied to suit the
design requirements of each electric motor.
[0079] As provided herein, electrical current (not shown) is
individually supplied to each conductor array by the control system
22. For each trim mover 114A, 114B, 116A, 116B, the electrical
current through the conductors causes the conductors to interact
with the magnetic field of the magnets. This generates a force
(Lorentz type force) between the magnets and the conductors which
can be used to control, move, and position one of the components
118, 120 relative to the other one of the components 118, 120.
[0080] For the embodiments, the first component 118 of each trim
mover 114A, 114B, 116A, 116B can be a magnet array and the second
component 120 can be a conductor array. Thus, for each trim mover
114A, 114B, 116A, 116B, the magnet array moves relative to each
conductor array.
[0081] Preferably, if the second component 120 of each trim mover
114A, 114B, 116A, 116B is a conductor array, the conductors are
individually controlled and switched electrically with the control
system 22 so that only conductors wholly and/or partially covered
by the magnet array are energized. In other words, only conductors
that are in a position to interact with the magnetic field of the
magnet array are energized. The current level for each conductor is
controlled and adjusted by the controller to achieve the desired
resultant forces. Not applying current to the conductors outside of
the magnetic field of the magnet array minimizes heat created by
the conductor array.
[0082] The measurement system 20 monitors movement of the stage 14
relative to the stage base 12, or to some other reference such as
an optical assembly 200 (illustrated in FIG. 8). With this
information, the stage mover assembly 16 can be used to precisely
position of the stage 14. The design of the measurement system 20
can be varied. For example, the measurement system 20 can utilize
laser interferometers, encoders, and/or other measuring devices to
monitor the position of the stage 14.
[0083] Typically, the measurement system 20 monitors the position
of the device table 48 along the X axis, along the Y axis, and
about the Z axis. More specifically, the measurement system 20
measures the position of the device table 48 relative to the guide
assembly 50 along the Y axis, and the measurement system 20
measures the position of the device table 48 along the Y axis,
along the X axis, and about the Z axis relative to the optical
assembly 200.
[0084] As provided herein, the measurement system 20 can utilize a
linear encoder (not shown) that measures the amount of movement of
device table 48 relative to the guide assembly 50 as the device
table 48 moves relative to the guide assembly 50. Alternately, for
example, an interferometer system (not shown) can be utilized. A
suitable interferometer system can be made with components obtained
from Agilent Technologies in Palo Alto, Calif.
[0085] Additionally, the measurement system 20 includes an XZ
interferometer 130 and a Y interferometer 132. The XZ
interferometer 130 includes an XZ mirror 134 and an XZ block 136.
The XZ block 136 interacts with the XZ mirror 134 to monitor the
location of the device table 48 along the X axis and about the Z
axis (theta Z). More specifically, the XZ block 136 generates a
pair of spaced apart laser signals (not shown) that are reflected
off of the XZ mirror 134. With this information, the location of
the device table 48 along the X axis and about the Z axis can be
monitored. Further, because the device table 48 does not move
relative to the guide assembly 50 along the X axis or about the Z
axis, the location of the guide assembly 50 along the X axis and
about the Z axis can also be monitored by the XZ interferometer
130.
[0086] In the embodiment illustrated in the Figures, the XZ mirror
134 is rectangular shaped and extends along one side of the device
table 48. The XZ block 136 is positioned away from the device table
48. The XZ block 136 can be secured to the apparatus frame 202
(illustrated in FIG. 8) or some other location that is isolated
from vibration.
[0087] Somewhat similarly, the Y interferometer 132 includes a Y
mirror 138 and a Y block 140. The Y mirror 138 interacts with the Y
block 140 to monitor the position of the device table 48 along the
Y axis. More specifically, the Y block 140 generates a laser signal
that is reflected off of the Y mirror 138. With this information,
the location of the device table 48 along the Y axis can be
monitored. Further, because the position of the device table 48
relative to the guide assembly 50 along the Y axis is measured with
the encoder, the position of the guide assembly 50 along the Y axis
can also be monitored.
[0088] In the embodiment illustrated in the Figures, the Y mirror
138 is rectangular shaped and is positioned along one of the sides
of the device table 48. The Y block 140 is positioned away from the
device table 48. The Y block 140 can be secured to the apparatus
frame 202 (illustrated in FIG. 8) or some other location that is
isolated from vibration.
[0089] Additionally, the measurement system 20 includes one or more
mass measuring devices 142 such as laser interferometers, encoders,
and/or other sensors to monitor (i) the position of the first
reaction mass 88 relative to the first mass guide 100, and (ii) the
position of the second reaction mass 90 relative to the second mass
guide 102.
[0090] The control system 22 controls the stage mover assembly 16
to precisely position the stage 14 and the device 26. In the
embodiment illustrated herein, the control system 22 directs and
controls the current to the conductor array for each of the X stage
movers 76A, 76B to control movement of the stage 14 along the X
axis and about the Z axis. Similarly, the control system 22 directs
and controls the current to conductor array of the Y table mover 80
and the conductors 98 of the Y guide movers 78A, 78B to control
movement of the stage 14 along the Y axis.
[0091] Additionally, the control system 22 directs and controls
current to the reaction mover assembly 38 to control the position
of the reaction masses 88, 90. More specifically, the control
system 22 directs current to (i) the conductor array for each first
trim movers 114A, 114B to independently control the position of the
first reaction mass 88 along the X axis, along the Y axis and about
the Z axis relative to the first mass guide 100, and (ii) the
conductor array for each second trim mover 116A, 116B to
independently control the position of the second reaction mass 90
along the X axis, along the Y axis and about the Z axis relative to
the second mass guide 102.
[0092] FIG. 6 illustrates a simplified schematic perspective view
of a portion of a stage assembly 10 that facilitates a discussion
of the movement of the stage 14 and the reaction assembly 18. In
particular, FIG. 6 illustrates the stage assembly 10 with the
device table 48 positioned approximately half-way between the
reaction masses 88, 90 along the Y axis.
[0093] The following symbols are used in conjunction with FIG. 6
and the discussion provided below to describe the movement and
control of the reaction assembly 18:
[0094] Mw represents the mass of the device table 48;
[0095] Mg represents the mass of the guide assembly 50;
[0096] Mx represents the mass of the stage 14 (Mx=Mw+Mg);
[0097] M1 represents the mass of the first reaction mass 88;
[0098] M2 represents the mass of the second reaction mass 90;
[0099] My represents the total reaction mass along the Y axis,
namely the combination of the mass of the guide assembly 50, the
mass of the first reaction mass 88, and the mass of the second
reaction mass (My=Mg+M1+M2);
[0100] Ayw represents the acceleration of the device table 48 along
the Y axis;
[0101] Axw represents the acceleration of device table 48 and guide
assembly 50 along the X axis;
[0102] Ay represents the acceleration of the guide assembly 50 and
both reaction masses 88, 90 along the Y axis;
[0103] Ax1 represents the acceleration of the first reaction mass
88 along the X axis;
[0104] Ax2 represents the acceleration of the second reaction mass
90 along the X axis;
[0105] Fy represents the force generated by the Y table mover 80
that drives the device table 48 along the Y axis;
[0106] Ry is the reaction force generated by the Y table mover 80
that acts upon the guide assembly 50, Ry is equal in magnitude but
in the opposite direction as Fy;
[0107] Fx1 represents the force generated by the first X stage
mover 76A on the guide assembly 50 to move the guide assembly 50
along the X axis;
[0108] Fx2 represents the force generated by the second X stage
mover 76B on the guide assembly 50 to move the guide assembly 50
along the X axis;
[0109] Rx1 represents the reaction force generated by the first X
stage mover 76A along the X axis that acts upon the first reaction
mass 88, Rx1 is equal in magnitude and opposite in direction to
Fx1;
[0110] Rx2 represents the reaction force generated by the second X
stage mover 76B along the X axis that acts upon the second reaction
mass 90, Rx2 is equal in magnitude and opposite in direction to
Fx2;
[0111] Fy1 represents the force generated by the first Y guide
mover 78A on the guide assembly 50;
[0112] Fy2 represents the force generated by the second Y guide
mover 78B on the guide assembly 50;
[0113] Ry1 represents the reaction force generated by the first Y
guide mover 78A along the Y axis that acts upon the first reaction
mass 88, Ry1 is equal in magnitude and opposite in direction to
Fy1;
[0114] Ry2 represents the reaction force generated by the second Y
guide mover 78B along the Y axis that acts upon the second reaction
mass 90, Ry2 is equal in magnitude and opposite in direction to
Fy2;
[0115] Fyg represents the total force acting on the guide assembly
50 along the Y axis;
[0116] Tx11 and Tx12 represent the forces along the X axis
generated by the first trim movers 114A and 114B respectively on
the first reaction mass 88 to move the first reaction mass 88 along
the X axis;
[0117] Tx21 and Yx22 represents the force along the X axis
generated by the second trim movers 116A and 116B respectively on
the second reaction mass 90 to move the second reaction mass 90
along the X axis;
[0118] Ty11 and Ty12 represents the force along the Y axis
generated by the first trim movers 114A and 114B respectively on
the first reaction mass 88 to move the first reaction mass 88 along
the Y axis;
[0119] Ty21 and Ty22 represents the force along the Y axis
generated by the second trim movers 116A and 116B respectively on
the second reaction mass 90 to move the second reaction mass 90
along the Y axis;
[0120] Rx11 and Rx12 represents the reaction force along the X axis
generated by the first trim movers 114A and 114B respectively that
acts upon the first mass guide 100, Rx11 is equal in magnitude and
opposite in direction of Tx11 and Tx12;
[0121] Rx21 and Rx22 represents the reaction force along the X axis
generated by the second trim movers 116A and 116B respectively that
acts upon the second mass guide 102, Rx21 and Rx22 are equal in
magnitude and opposite in direction of Tx21 and Tx22;
[0122] Ry11 and Ry12 represents the reaction force along the Y axis
generated by the first trim movers 114A and 114B respectively that
acts upon the first mass guide 100, Ry11 and Ry12 are equal in
magnitude and opposite in direction of Ty11 and Ty12;
[0123] Ry21 and Ry22 represents the reaction force along the Y axis
generated by the second trim movers 116A and 116B respectively that
acts upon the second mass guide 102, Rx21 and Ry22 are equal in
magnitude and opposite in direction of Ty21 and Ty22;
[0124] Y1 represents the distance along the Y axis between the
center of the device table 48 and the center of the first reaction
mass 88;
[0125] Y2 represents the distance along the Y axis between the
center of the device table 48 and the center of the second reaction
mass 90;
[0126] X11 represents the distance along the X axis from the center
of the guide assembly 50 to the center of the front first trim
mover 114B of the first reaction mass 88;
[0127] X12 represents the distance along the X axis between the
center of the guide assembly 50 and the center of the rear first
trim mover 11 4A of the first reaction mass 88;
[0128] X21 represents the distance along the X axis between the
center of the guide assembly 50 and the center of the front second
trim mover 116A of the second reaction mass 90;
[0129] X22 represents the distance along the X axis between the
center of the guide assembly 50 and the center of the rear second
trim mover 116B of the second reaction mass 90;
[0130] X.sub.a represents the distance along the X axis between the
center of the first reaction mass 88 and the center of the guide
assembly 50 [X.sub.a=(X.sub.11-X.sub.12)/2], X.sub.a is not
illustrated in FIG. 6; and
[0131] X.sub.b represents the distance along the X axis between the
center of the second reaction mass 90 and the center of the guide
assembly 50 [X.sub.b=(X.sub.21-X.sub.22)/2], X.sub.b is not
illustrated in FIG. 6:
[0132] Y Axis Equations
[0133] The force generated by the Y table mover 80 on the device
table 48 along the Y axis is determined by Newton's second law:
Fy=Mw*Ayw
[0134] The reaction force Ry acts upon the reaction masses 88, 90
and the guide assembly 50 in the opposite direction along the Y
axis. Collectively, these three bodies are represented by My. When
the device table 48 is accelerated along the Y axis, My accelerates
in the opposite direction. The ratio of the accelerations is the
inverse ratio of the masses.
Ayw*Mw=-Ay*My
[0135] Along the Y axis Ry1 acts upon the first reaction mass 88
and Ry2 acts upon the second reaction mass 90. Ay can be used to
find the Y reaction force required to accelerate each reaction mass
88, 90 is:
Ry1=Ay*M1=-(Ayw*Mw)(M1/My)
Ry2=Ay*M2=-(Ayw*Mw)(M2/My)
[0136] Because the reaction forces (Ry1 and Ry2) are equal and
opposite the forces acting on the guide assembly 50, the following
equations are applicable:
Fy1=-Ry1=Fy(M1/My)
Fy2=-Ry2=Fy(M2/My)
[0137] The forces along the Y axis acting on the guide assembly 50
are Ry, Fy1, and Fy2. Using these forces, the net force along the Y
axis acting on the guide assembly 50, Fyg:
Ry=-Fy
Fyg=Ry+Fy1+Fy2
Fyg=-Fy+Fy(M1/My)+Fy(M2/My)
Fyg=Fy(M1+M2-My)/My
[0138] Using the fact that My=M1+M2+Mg,
Fyg=-Fy*Mg/My
[0139] Substituting for Fy gives
Fyg=Mg*(-Ayw*Mw)/My
[0140] Which simplifies to
Fyg=Mg*Ay
[0141] This proves that using the equations above for Fy1 and Fy2
will give both reaction masses 88, 90 and the guide assembly 50 the
same acceleration along the Y axis, so they all move together along
the Y axis.
[0142] X Axis Equations
[0143] Along the X axis, the force balance between the first X
stage mover 76A and the second X stage mover 76B can be found from
these equations:
Axw*Mx=Fx1+Fx2
Fx1*Y1=Fx2*Y2
[0144] Solving for Fx1 and Fx2:
Fx1=Axw*Mx*Y2/(Y1+Y2)
Fx2=Axw*Mx*Y1/(Y1+Y2)
[0145] The corresponding reaction forces accelerate the reaction
masses 88, 90 along the X axis:
Ax1=Rx1/M1=-Fx1/M1
Ax2=Rx2/M2=-Fx2/M2
[0146] This illustrates that the two reaction masses 88, 90 will
experience different accelerations in the X direction.
[0147] Trim Force Equations:
[0148] Theoretically, the net trim force along the X axis and the Y
axis on each reaction mass 88, 90 should be zero. In practice, some
trim force along the X axis and the Y axis from the trim movers
114A, 114B, 116A, 116B will be required to compensate for external
disturbances, or to reduce the stroke of the reaction masses 88,
90. Some trim force is needed, however, to counteract torque on the
reaction masses 88, 90 when the guide assembly 50 is not centered
along the X axis.
[0149] For the first reaction mass 88, Ti defines the magnitude of
trim force by the first trim movers 114A, 114B required to cancel
torque on the first reaction mass 88:
T1=Ty11=-Ty12=Ry1*X.sub.a/(X11+X12)
[0150] Substituting Ry1=-Fy1 gives the force required from each of
the first trim movers 114A, 114B along the Y axis. The same
analysis applies to second reaction mass 90.
Ty11=-Fy1*X.sub.a/(X11+X12)
Ty12=Fy1*X.sub.a/(X11+X12)
Ty21=-Fy2*X.sub.b/(X21+X22)
Ty22=Fy2*X.sub.b/(X21+X22)
[0151] FIG. 7 illustrates a second embodiment of a stage assembly
10 having features of the present invention. In this embodiment,
stage assembly 10 includes the stage base 12, the stage mover
assembly 16, the reaction assembly 18, the measurement system 20,
and the control system 22 similar to the equivalent components
described above. However, in this embodiment, the stage assembly 10
includes two stages 14 that are moved independently by the stage
mover assembly 16.
[0152] FIG. 8 is a schematic view illustrating an exposure
apparatus 30 useful with the present invention. The exposure
apparatus 30 includes the apparatus frame 202, an illumination
system 204 (irradiation apparatus), a reticle stage assembly 206,
the optical assembly 200 (lens assembly), and a wafer stage
assembly 210. The stage assemblies 10 provided herein can be used
as the wafer stage assembly 210. Alternately, with the disclosure
provided herein, the stage assemblies 10 provided herein can be
modified for use as the reticle stage assembly 206.
[0153] The exposure apparatus 30 is particularly useful as a
lithographic device that transfers a pattern (not shown) of an
integrated circuit from the reticle 32 onto the semiconductor wafer
28. The exposure apparatus 30 mounts to the mounting base 24, e.g.,
the ground, a base, or floor or some other supporting
structure.
[0154] The apparatus frame 202 is rigid and supports the components
of the exposure apparatus 30. The design of the apparatus frame 202
can be varied to suit the design requirements for the rest of the
exposure apparatus 30. The apparatus frame 202 illustrated in FIG.
8 supports the optical assembly 200 and the illumination system 204
and the reticle stage assembly 206 above the mounting base 24.
[0155] The illumination system 200 includes an illumination source
212 and an illumination optical assembly 214. The illumination
source 212 emits a beam (irradiation) of light energy. The
illumination optical assembly 214 guides the beam of light energy
from the illumination source 212 to the optical assembly 200. The
beam illuminates selectively different portions of the reticle 32
and exposes the semiconductor wafer 28. In FIG. 8, the illumination
source 212 is illustrated as being supported above the reticle
stage assembly 206. Typically, however, the illumination source 212
is secured to one of the sides of the apparatus frame 202 and the
energy beam from the illumination source 212 is directed to above
the reticle stage assembly 206 with the illumination optical
assembly 214.
[0156] The optical assembly 200 projects and/or focuses the light
passing through the reticle to the wafer. Depending upon the design
of the exposure apparatus 30, the optical assembly 200 can magnify
or reduce the image illuminated on the reticle.
[0157] The reticle stage assembly 206 holds and positions the
reticle relative to the optical assembly 200 and the wafer.
Similarly, the wafer stage assembly 210 holds and positions the
wafer with respect to the projected image of the illuminated
portions of the reticle in the operational area. In FIG. 8, the
wafer stage assembly 210 utilizes a stage assembly 10 having
features of the present invention. Depending upon the design, the
exposure apparatus 30 can also include additional motors to move
the stage assemblies 206, 210.
[0158] There are a number of different types of lithographic
devices. For example, the exposure apparatus 30 can be used as
scanning type photolithography system that exposes the pattern from
the reticle onto the wafer with the reticle and the wafer moving
synchronously. In a scanning type lithographic device, the reticle
is moved perpendicular to an optical axis of the optical assembly
200 by the reticle stage assembly 206 and the wafer is moved
perpendicular to an optical axis of the optical assembly 200 by the
wafer stage assembly 210. Scanning of the reticle and the wafer
occurs while the reticle and the wafer are moving
synchronously.
[0159] Alternately, the exposure apparatus 30 can be a
step-and-repeat type photolithography system that exposes the
reticle while the reticle and the wafer are stationary. In the step
and repeat process, the wafer is in a constant position relative to
the reticle and the optical assembly 200 during the exposure of an
individual field. Subsequently, between consecutive exposure steps,
the wafer is consecutively moved by the wafer stage perpendicular
to the optical axis of the optical assembly 200 so that the next
field of the wafer is brought into position relative to the optical
assembly 200 and the reticle for exposure. Following this process,
the images on the reticle are sequentially exposed onto the fields
of the wafer so that the next field of the wafer is brought into
position relative to the optical assembly 200 and the reticle.
[0160] However, the use of the exposure apparatus 30 and the stage
assembly 10 provided herein are not limited to a photolithography
system for semiconductor manufacturing. The exposure apparatus 30,
for example, can be used as an LCD photolithography system that
exposes a liquid crystal display device pattern onto a rectangular
glass plate or a photolithography system for manufacturing a thin
film magnetic head. Further, the present invention can also be
applied to a proximity photolithography system that exposes a mask
pattern by closely locating a mask and a substrate without the use
of a lens assembly. Additionally, the present invention provided
herein can be used in other devices, including other semiconductor
processing equipment, elevators, electric razors, machine tools,
metal cutting machines, inspection machines and disk drives.
[0161] The illumination source 212 can be g-line (436 nm), i-line
(365 nm), KrF excimer laser (248 nm), ArF excimer laser (193 nm)
and F.sub.2 laser (157 nm). Alternately, the illumination source
212 can also use charged particle beams such as an x-ray and
electron beam. For instance, in the case where an electron beam is
used, thermionic emission type lanthanum hexaboride (LaB.sub.6) or
tantalum (Ta) can be used as an electron gun. Furthermore, in the
case where an electron beam is used, the structure could be such
that either a mask is used or a pattern can be directly formed on a
substrate without the use of a mask.
[0162] In terms of the magnification of the optical assembly 200
included in the photolithography system, the optical assembly 200
need not be limited to a reduction system. It could also be a
1.times. or magnification system.
[0163] With respect to a optical assembly 200, when far
ultra-violet rays such as the excimer laser is used, glass
materials such as quartz and fluorite that transmit far
ultra-violet rays is preferable to be used. When the F.sub.2 type
laser or x-ray is used, the optical assembly 200 should preferably
be either catadioptric or refractive (a reticle should also
preferably be a reflective type), and when an electron beam is
used, electron optics should preferably consist of electron lenses
and deflectors. The optical path for the electron beams should be
in a vacuum.
[0164] Also, with an exposure device that employs vacuum
ultra-violet radiation (VUV) of wavelength 200 nm or lower, use of
the catadioptric type optical system can be considered. Examples of
the catadioptric type of optical system include the disclosure
Japan Patent Application Disclosure No.8-171054 published in the
Official Gazette for Laid-Open Patent Applications and its
counterpart U.S. Pat. No. 5,668,672, as well as Japan Patent
Application Disclosure No.10-20195 and its counterpart U.S. Pat.
No. 5,835,275. In these cases, the reflecting optical device can be
a catadioptric optical system incorporating a beam splitter and
concave mirror. Japan Patent Application Disclosure No.8-334695
published in the Official Gazette for Laid-Open Patent Applications
and its counterpart U.S. Pat. No. 5,689,377 as well as Japan Patent
Application Disclosure No.10-3039 and its counterpart U.S. patent
application Ser. No. 873,605 (Application Date: Jun. 12, 1997) also
use a reflecting-refracting type of optical system incorporating a
concave mirror, etc., but without a beam splitter, and can also be
employed with this invention. As far as is permitted, the
disclosures in the above-mentioned U.S. patents, as well as the
Japan patent applications published in the Official Gazette for
Laid-Open Patent Applications are incorporated herein by
reference.
[0165] Further, in photolithography systems, when linear motors
(see U.S. Pat. Nos. 5,623,853 or 5,528,118) are used in a wafer
stage or a mask stage, the linear motors can be either an air
levitation type employing air bearings or a magnetic levitation
type using Lorentz force or reactance force. Additionally, the
stage could move along a guide, or it could be a guideless type
stage that uses no guide. As far as is permitted, the disclosures
in U.S. Pat. Nos. 5,623,853 and 5,528,118 are incorporated herein
by reference.
[0166] Alternatively, one of the stages could be driven by a planar
motor, which drives the stage by an electromagnetic force generated
by a magnet unit having two-dimensionally arranged magnets and an
armature coil unit having two-dimensionally arranged coils in
facing positions. With this type of driving system, either the
magnet unit or the armature coil unit is connected to the stage and
the other unit is mounted on the moving plane side of the
stage.
[0167] Movement of the stages as described above generates reaction
forces that can affect performance of the photolithography system.
Reaction forces generated by the wafer (substrate) stage motion can
be mechanically released to the floor (ground) by use of a frame
member as described in U.S. Pat. No. 5,528,118 and published
Japanese Patent Application Disclosure No. 8-136475. Additionally,
reaction forces generated by the reticle (mask) stage motion can be
mechanically released to the floor (ground) by use of a frame
member as described in U.S. Pat. No. 5,874,820 and published
Japanese Patent Application Disclosure No. 8-330224. As far as is
permitted, the disclosures in U.S. Pat. Nos. 5,528,118 and
5,874,820 and Japanese Patent Application Disclosure No. 8-330224
are incorporated herein by reference.
[0168] As described above, a photolithography system according to
the above described embodiments can be built by assembling various
subsystems, including each element listed in the appended claims,
in such a manner that prescribed mechanical accuracy, electrical
accuracy, and optical accuracy are maintained. In order to maintain
the various accuracies, prior to and following assembly, every
optical system is adjusted to achieve its optical accuracy.
Similarly, every mechanical system and every electrical system are
adjusted to achieve their respective mechanical and electrical
accuracies. The process of assembling each subsystem into a
photolithography system includes mechanical interfaces, electrical
circuit wiring connections and air pressure plumbing connections
between each subsystem. Needless to say, there is also a process
where each subsystem is assembled prior to assembling a
photolithography system from the various subsystems. Once a
photolithography system is assembled using the various subsystems,
a total adjustment is performed to make sure that accuracy is
maintained in the complete photolithography system. Additionally,
it is desirable to manufacture an exposure system in a clean room
where the temperature and cleanliness are controlled.
[0169] Further, semiconductor devices can be fabricated using the
above described systems, by the process shown generally in FIG. 9.
In step 301 the device's function and performance characteristics
are designed. Next, in step 302, a mask (reticle) having a pattern
is designed according to the previous designing step, and in a
parallel step 303 a wafer is made from a silicon material. The mask
pattern designed in step 302 is exposed onto the wafer from step
303 in step 304 by a photolithography system described hereinabove
in accordance with the present invention. In step 305 the
semiconductor device is assembled (including the dicing process,
bonding process and packaging process), finally, the device is then
inspected in step 306.
[0170] FIG. 10 illustrates a detailed flowchart example of the
above-mentioned step 304 in the case of fabricating semiconductor
devices. In FIG. 10, in step 311 (oxidation step), the wafer
surface is oxidized. In step 312 (CVD step), an insulation film is
formed on the wafer surface. In step 313 (electrode formation
step), electrodes are formed on the wafer by vapor deposition. In
step 314 (ion implantation step), ions are implanted in the wafer.
The above mentioned steps 311-314 form the preprocessing steps for
wafers during wafer processing, and selection is made at each step
according to processing requirements.
[0171] At each stage of wafer processing, when the above-mentioned
preprocessing steps have been completed, the following
post-processing steps are implemented. During post-processing,
first, in step 315 (photoresist formation step), photoresist is
applied to a wafer. Next, in step 316 (exposure step), the
above-mentioned exposure device is used to transfer the circuit
pattern of a mask (reticle) to a wafer. Then in step 317
(developing step), the exposed wafer is developed, and in step 318
(etching step), parts other than residual photoresist (exposed
material surface) are removed by etching. In step 319 (photoresist
removal step), unnecessary photoresist remaining after etching is
removed.
[0172] Multiple circuit patterns are formed by repetition of these
preprocessing and post-processing steps.
[0173] While the particular stage assembly 10 as shown and
disclosed herein is fully capable of obtaining the objects and
providing the advantages herein before stated, it is to be
understood that it is merely illustrative of the presently
preferred embodiments of the invention and that no limitations are
intended to the details of construction or design herein shown
other than as described in the appended claims.
* * * * *