Title: Vibration isolator with low lateral stiffness
Abstract: A vibration isolator (200) for isolating a first assembly (202) from vibration from a second assembly (204) includes a housing (206) that is secured to the second assembly (204) and a pendulum assembly (208). The pendulum assembly (208) includes one or more pistons (226) and a connector assembly (224). The piston (226) is coupled to the first assembly (202). The connector assembly (224) couples the piston (226) to the housing (206) and allows the piston (226) to swing laterally relative to the housing (206). The vibration isolator (200) can also include a pendulum support (264) and/or a mover (580) that moves the piston (226) and assists in supporting the load of the first assembly (202).
Patent Number: 6,953,109 Issued on 10/11/2005 to Watson, et al.
| Inventors:
|
Watson; Douglas C. (Campbell, CA);
Phillips; Alton H. (Mountain View, CA)
|
| Assignee:
|
Nikon Corporation (JP)
|
| Appl. No.:
|
267489 |
| Filed:
|
October 8, 2002 |
| Current U.S. Class: |
188/378; 248/631; 267/136; 355/53 |
| Intern'l Class: |
F16F 007/10 |
| Field of Search: |
188/378,379,380
267/136,195,642.7,642.8
248/631,622,636
355/53
|
References Cited [Referenced By]
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| 5285995 | Feb., 1994 | Gonzalez et al.
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| 5570298 | Oct., 1996 | Yasuda.
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| 5579084 | Nov., 1996 | Takahashi et al.
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| 5660255 | Aug., 1997 | Schubert et al.
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| 5701041 | Dec., 1997 | Akutsu et al.
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| 5779010 | Jul., 1998 | Nelson.
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| 5823307 | Oct., 1998 | Schubert et al.
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| 5918862 | Jul., 1999 | Nelson.
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| 6123312 | Sep., 2000 | Dai.
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| 6144442 | Nov., 2000 | Mannetje et al.
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| 6226075 | May., 2001 | Loopstra et al.
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| 6547225 | Apr., 2003 | Nelson.
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| 6568666 | May., 2003 | Houghton, Jr.
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| 6619611 | Sep., 2003 | Ryaboy et al.
| |
| Foreign Patent Documents |
| 0973067 | Jan., 2000 | EP.
| |
| 1160628 | Dec., 2001 | EP.
| |
| 62-60568 | Dec., 1987 | JP.
| |
| 08-287347 | Jan., 1996 | JP.
| |
| 8-170689 | Jul., 1996 | JP.
| |
Primary Examiner: Siconolfi; Robert A.
Assistant Examiner: Sy; Mariano
Attorney, Agent or Firm: Roeder; Steven G., Rose; Jim
Claims
1. A vibration isolator that at least partly isolates a first assembly from vibration
from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a sleeve positioned within the housing;
a connector assembly that flexibly connects the sleeve to the housing and allows
the sleeve to move relative to the housing substantially transverse to the first
axis;
a first piston that is coupled to the first assembly;
a first piston seal that seals the first piston to the sleeve; and
a pendulum support including a resilient member that flexibly connects the sleeve
to the first piston.
2. The vibration isolator of claim 1 wherein the pendulum support includes a
support beam that extends across the sleeve and the resilient member flexibly connects
the support beam to the first piston.
3. The vibration isolator of claim 1 wherein during lateral movement of the first
assembly, the first piston moves laterally relative to the first axis along a substantially
arc shaped path.
4. The vibration isolator of claim 1 further comprising a fluid source that adjusts
the pressure of a first fluid that acts upon the first piston to move the first
piston along the first axis.
5. The vibration isolator of claim 1 wherein the connector assembly includes
a connector center point located along the first axis and the first piston swings
relative to the housing about a movement axis that is located near the connector
center point.
6. The vibration isolator of claim 5 wherein the movement axis is positioned
between the first assembly and the second assembly.
7. The vibration isolator of claim 5 wherein the connector assembly includes
a connector area of motion that is annular shaped and the movement axis is positioned
at approximately the center of the connector area of motion.
8. The vibration isolator of claim 7 wherein the first piston seal includes a
seal area of motion that is annular shaped, wherein the connector area of motion
has a diameter that is approximately equal to a diameter of the seal area of motion.
9. The vibration isolator of claim 8 wherein the connector area of motion is
substantially coaxial with the seal area of motion.
10. A vibration isolator that at least partly isolates a first assembly from
vibration from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a sleeve positioned within the housing;
a connector assembly that flexibly connects the sleeve to the housing and allows
the sleeve to move relative to the housing substantially transverse to the first
axis;
a first piston that is coupled to the first assembly;
a first piston seal that seals the first piston to the sleeve;
a pendulum support that flexibly connects the sleeve to the first piston; and
a second piston that is coupled to the first piston, wherein the pistons move
concurrently laterally relative to the first axis.
11. The vibration isolator of claim 10 wherein the pistons move concurrently
along the first axis.
12. The vibration isolator of claim 10 further comprising a fluid source that
controls the pressure that acts on each piston.
13. The vibration isolator of claim 10 wherein the connector assembly includes
a first connector and a second connector, each connector being centered about a
central point that is located along the first axis and wherein the pistons pivot
relative to the housing about a movement axis that is located along the first axis
between the central points of the connectors.
14. A vibration isolator that at least partly isolates a first assembly from
vibration from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a sleeve positioned within the housing;
a connector assembly that flexibly connects the sleeve to the housing and allows
the sleeve to move relative to the housing substantially transverse to the first
axis;
a first piston that is coupled to the first assembly;
a first piston seal that seals the first piston to the sleeve;
a pendulum support that flexibly connects the sleeve to the first piston; and
a mover that moves the first piston relative to the housing.
15. The vibration isolator of claim 14 wherein the mover includes a first mover
component coupled to the first piston, and a second mover component coupled to
the housing.
16. The vibration isolator of claim 15 wherein the first mover component moves
concurrently with the first piston laterally relative to the first axis and along
the first axis.
17. The vibration isolator of claim 15 wherein one of the mover components includes
a magnet and the other mover component includes a conductor.
18. The vibration isolator of claim 15 wherein the pendulum assembly includes
a piston shaft that couples the first piston to the first assembly, and wherein
the first mover component is secured to the piston shaft.
19. An isolation system including the vibration isolator of claim 1.
20. An exposure apparatus including the isolation system of claim 19.
21. A device manufactured with the exposure apparatus according to claim 20.
22. A wafer on which an image has been formed by the exposure apparatus of claim 20.
23. A vibration isolator that at least partly isolates a first assembly from
vibration from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a pendulum assembly coupled to the housing, the pendulum assembly including a
first piston and a second piston that are coupled to the first assembly and a connector
assembly that allows the pistons to move concurrently laterally relative to the
first axis; and
a fluid source that adjusts the pressure of a first fluid that acts upon the
first piston and a second fluid that acts upon the second piston.
24. The vibration isolator of claim 23 wherein the pistons move concurrently
along the first axis.
25. The vibration isolator of claim 23 wherein the fluid source controls the
pressure below each piston.
26. The vibration isolator of claim 23 wherein the connector assembly includes
a first connector and a second connector, each connector being centered about a
central point that is located along the first axis and wherein the pistons pivot
relative to the housing about a movement axis that is located along the first axis
between the central points of the connectors.
27. The vibration isolator of claim 23 wherein the pendulum assembly further
comprises a sleeve positioned within the housing, and a seal assembly that seals
the pistons to the sleeve, and wherein the connector assembly flexibly connects
the sleeve to the housing and allows the sleeve to move relative to the housing
substantially transverse to the first axis.
28. The vibration isolator of claim 27 further comprising a pendulum support
that flexibly connects the sleeve to the pistons.
29. The vibration isolator of claim 28 wherein the pendulum support includes
a support beam that extends across the sleeve and a resilient member that flexibly
connects the support beam to at least one of the pistons.
30. The vibration isolator of claim 23 wherein the pendulum assembly further
comprises a third piston that is coupled to the first piston and the second piston,
and wherein the connector assembly allows the first piston, the second piston and
the third piston to swing concurrently laterally relative to the first axis.
31. The vibration isolator of claim 23 wherein the first fluid and the second
fluid are at the same pressure.
32. An isolation system including the vibration isolator of claim 23.
33. An exposure apparatus including the isolation system of claim 32.
34. A device manufactured with the exposure apparatus according to claim 33.
35. A wafer on which an image has been formed by the exposure apparatus of claim 33.
36. A vibration isolator that at least partly isolates a first assembly from
vibration from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a pendulum assembly coupled to the housing, the pendulum assembly including a
first piston that is coupled to the first assembly and a connector assembly that
allows the first piston to swing substantially laterally relative to the first
axis, the first piston including a first side and a second side;
a mover that is coupled to the first piston, the mover moving the first piston
relative to the housing along the first axis; and
a fluid source that adjusts the pressure of a fluid that acts upon the first
side of the first piston without acting on the second side to move the piston along
the first axis.
37. A vibration isolator that at least partly isolates a first assembly from
vibration from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a pendulum assembly coupled to the housing, the pendulum assembly including a
first piston that is coupled to the first assembly and a connector assembly that
allows the first piston to swing substantially laterally relative to the first
axis;
a mover that is coupled to the first piston, the mover moving the first piston
relative to the housing along the first axis, wherein the mover includes a first
mover component coupled to the first piston, and a second mover component coupled
to the housing; and
a fluid source that adjusts the pressure of a fluid that acts upon the first
piston to move the piston along the first axis.
38. The vibration isolator of claim 37 wherein the first mover component moves
concurrently with the first piston laterally relative to the first axis and along
the first axis.
39. The vibration isolator of claim 37 wherein one of the mover components includes
a magnet and the other mover component includes a conductor.
40. The vibration isolator of claim 37 wherein the pendulum assembly includes
a piston shaft that couples the first piston to the first assembly, and wherein
the first mover component is secured to the piston shaft.
41. The vibration isolator of claim 36 wherein the connector assembly includes
a connector center point located along the first axis and the first piston swings
relative to the housing about a movement axis that is located near the connector
center point.
42. The vibration isolator of claim 36 further comprising a second piston that
is coupled to the first piston, wherein the pistons move concurrently laterally
relative to the first axis, and the pistons move concurrently along the first axis.
43. A vibration isolator that at least partly isolates a first assembly from
vibration from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a pendulum assembly coupled to the housing, the pendulum assembly including a
first piston that is coupled to the first assembly and a connector assembly that
allows the first piston to swing substantially laterally relative to the first
axis, wherein the pendulum assembly further comprises a sleeve positioned within
the housing, and a seal assembly that seals the first piston to the sleeve, and
wherein the connector assembly flexibly connects the sleeve to the housing and
allows the sleeve to move relative to the housing substantially transverse to the
first axis;
a mover that is coupled to the first piston, the mover moving the first piston
relative to the housing along the first axis: and
a fluid source that adjusts the pressure of a fluid that acts upon the first
piston to move the piston along the first axis.
44. The vibration isolator of claim 43 further comprising a pendulum support
that flexibly connects the sleeve to the first piston.
45. An isolation system including the vibration isolator of claim 36.
46. An exposure apparatus including the isolation system of claim 45.
47. A device manufactured with the exposure apparatus according to claim 46.
48. A wafer on which an image has been formed by the exposure apparatus of claim 46.
49. A vibration isolator that at least partly isolates a first assembly from
vibration from a second assembly along a first axis, the vibration isolator comprising:
a housing that is secured to the second assembly;
a pendulum assembly including a shaft that is secured to the first assembly and
a connector assembly that connects the shaft to the housing and allows the shaft
to swing substantially laterally relative to the first axis; and
a mover including a first mover component secured to the shaft and a second mover
component that is secured to the housing.
50. The vibration isolator of claim 49 wherein the pendulum assembly includes
a piston that is secured to the shaft.
51. The vibration isolator of claim 50 wherein the piston moves concurrently
with the first mover component laterally relatively to the first axis and along
the first axis.
52. The vibration isolator of claim 51 further comprising a fluid source that
adjusts the pressure of a fluid that acts upon the piston to move the piston along
the first axis.
53. The vibration isolator of claim 49 wherein one of the mover components includes
a magnet and the other mover component includes a conductor.
54. The vibration isolator of claim 49 wherein the connector assembly includes
a connector center point located along the first axis and the first mover component
swings relative to the housing about a movement axis that is located near the connector
center point.
55. The vibration isolator of claim 54 wherein the movement axis is positioned
along the first axis between a central point of the first assembly and a central
point of the second assembly.
56. An isolation system including the vibration isolator of claim 49.
57. An exposure apparatus including the isolation system of claim 56.
58. A device manufactured with the exposure apparatus according to claim 57.
59. A wafer on which an image has been formed by the exposure apparatus of claim 57.
60. A method for making a vibration isolator for isolating a first assembly from
vibration from a second assembly along a first axis, the method comprising the
steps of:
providing a housing that is secured to the second assembly;
positioning a sleeve within the housing;
flexibly connecting the sleeve to the housing with a connector assembly that
allows the sleeve to move relative to the housing substantially transverse to the
first axis;
coupling a first piston to the first assembly;
sealing the first piston to the sleeve with a first seal; and
flexibly connecting the sleeve to the first piston with a resilient member of
a pendulum support.
61. The method of claim 60 wherein the step of flexibly connecting includes the
step of providing a support beam that extends across the sleeve and the resilient
member flexibly connects the support beam to the first piston.
62. The method of claim 60 wherein during lateral movement of the first assembly,
the first piston moves laterally relative to the first axis along a substantially
arc shaped path.
63. The method of claim 60 further comprising the step of adjusting the pressure
of a first fluid that acts upon the first piston to move the first piston along
the first axis.
64. A method for making a vibration isolator for isolating a first assembly from
vibration from a second assembly along a first axis, the method comprising the
steps of:
providing a housing that is secured to the second assembly;
positioning a sleeve within the housing;
flexibly connecting the sleeve to the housing with a connector assembly that
allows the sleeve to move relative to the housing substantially transverse to the
first axis;
coupling a first piston to the first assembly;
sealing the first piston to the sleeve with a first seal;
flexibly connecting the sleeve to the first piston with a pendulum support; and
coupling a second piston to the first piston, wherein the pistons move concurrently
laterally relative to the first axis and wherein the pistons move concurrently
along the first axis.
65. The method of claim 60 further comprising the step of moving the first piston
relative to the housing with a mover.
66. A method for making a vibration isolator for isolating a first assembly from
vibration from a second assembly along a first axis, the method comprising the
steps of:
providing a housing that is secured to the second assembly;
positioning a sleeve within the housing;
flexibly connecting the sleeve to the housing with a connector assembly that
allows the sleeve to move relative to the housing substantially transverse to the
first axis;
coupling a first piston to the first assembly;
sealing the first piston to the sleeve with a first seal;
flexibly connecting the sleeve to the first piston with a pendulum support; and
moving the first piston relative to the housing with a mover, wherein the step
of moving includes the step of coupling a first mover component to the first piston,
and coupling a second mover component to the housing.
67. The method of claim 66 wherein the first mover component moves concurrently
with the first piston laterally relative to the first axis and along the first axis.
68. A method for making an isolation system including the step of providing a
vibration isolator made in accordance with claim 60.
69. A method for providing an exposure apparatus including the step of providing
a first assembly, providing a second assembly, and securing the first assembly
to the second assembly with a vibration isolator made by the method of claim 60.
70. A method of making a wafer utilizing the exposure apparatus made by the method
of claim 69.
71. A method of making a device including at least an exposure process, wherein
the exposure process utilizes the exposure apparatus made by the method of claim 69.
72. A method for making a vibration isolator for isolating a first assembly from
vibration from a second assembly along a first axis, the method comprising the
steps of:
providing a housing that is secured to the second assembly;
coupling a first piston and a second piston to the first assembly;
connecting the pistons to the housing with a connector assembly that allows the
pistons to move concurrently laterally relative to the first axis; and
adjusting the pressure of a first fluid that acts upon the first piston and a
second fluid that acts upon the second piston with a fluid source to move the pistons
concurrently along the first axis.
73. The method of claim 72 wherein during lateral movement of the first assembly,
the pistons move concurrently along a substantially arc shaped path.
74. The method of claim 72 further comprising the step of moving the pistons
relative to the housing with a mover.
75. The method of claim 74 wherein the step of moving includes the step of coupling
a first mover component to the pistons, and coupling a second mover component to
the housing.
76. The method of claim 75 wherein the first mover component moves concurrently
with the pistons laterally to the first axis and along the first axis.
77. A method for making an isolation system including the step of providing a
vibration isolator made in accordance with claim 72.
78. A method for providing an exposure apparatus including the step of providing
a first assembly, providing a second assembly, and securing the first assembly
to the second assembly with a vibration isolator made by the method of claim 72.
79. A method of making a wafer utilizing the exposure apparatus made by the method
of claim 78.
80. A method of making a device including at least an exposure process, wherein
the exposure process utilizes the exposure apparatus made by the method of claim 78.
81. A method for making a vibration isolator for isolating a first assembly from
vibration from a second assembly along a first axis, the method comprising the
steps of:
providing a housing that is secured to the second assembly; securing a shaft
to the first assembly;
flexibly connecting the shaft to the housing with a connector assembly that allows
the shaft to swing substantially laterally relative to the first axis; and
providing a mover having a first mover component secured to the shaft and a second
mover component that is secured to the housing, the mover components interacting
to move the shaft relative to the housing along the first axis.
82. The method of claim 81 further comprising the step of coupling a piston to
the piston shaft, wherein during lateral movement of the first assembly, the first
piston and the first mover component move concurrently laterally relative to the
first axis.
83. The method of claim 81 wherein one of the mover components includes a magnet
and the other mover component includes a conductor.
84. A method for making an isolation system including the step of providing a
vibration isolator made in accordance with claim 81.
85. A method for providing an exposure apparatus including the step of providing
a first assembly, providing a second assembly, and securing the first assembly
to the second assembly with a vibration isolator made by the method of claim 81.
86. A method of making a wafer utilizing the exposure apparatus made by the method
of claim 85.
87. A method of making a device including at least an exposure process, wherein
the exposure process utilizes the exposure apparatus made by the method of claim 85.
Description
FIELD OF THE INVENTION
The present invention is directed to a vibration isolator and a method for making
a vibration isolator having a relatively low lateral stiffness and/or a relatively
high carrying capacity.
BACKGROUND
Exposure apparatuses are commonly used to transfer images from a reticle
onto a semiconductor wafer during semiconductor processing. A typical exposure
apparatus includes an apparatus frame, a measurement system, a control system,
an illumination source, an optical assembly, a reticle stage assembly, and a wafer
stage assembly.
The apparatus frame typically supports the measurement system, the illumination
source, the reticle stage, the optical assembly, and the wafer stage above a mounting
base. The measurement system monitors the positions of the stages relative to a
reference such as the optical assembly. The optical assembly projects and/or focuses
the light that passes through the reticle. The reticle stage assembly precisely
positions the reticle relative to the optical assembly. Somewhat similarly, the
wafer stage assembly precisely positions the wafer relative to the projected image
from the reticle.
The size of the images and the features within the images transferred onto the
wafer from the reticle are extremely small. Accordingly, the precise positioning
of the wafer and the reticle relative to the optical assembly is critical to the
manufacture of high density, semiconductor wafers.
Unfortunately, mechanical vibrations and deformations in the apparatus
frame of the exposure apparatus can influence the accuracy of the exposure apparatus.
For example, one or more movers utilized in the stage assemblies generate reaction
forces that vibrate and deform the apparatus frame of the exposure apparatus. Further,
the mounting base can transfer vibration to the apparatus frame.
The vibrations and deformations in the apparatus frame can move the stages and
the optical assembly out of precise relative alignment. Further, the vibrations
and deformations in the apparatus frame can cause the measurement system to improperly
measure the relative positions of the stages. Additionally, vibration of the optical
assembly can cause deformations of the optical elements within the optical assembly
and degrade the optical imaging quality. As a result thereof, the accuracy of the
exposure apparatus and the quality of the integrated circuits formed on the wafer
can be compromised.
One attempt to solve this problem involves the use of one or more air mounts
to secure the apparatus frame to the ground. The air mounts reduce the effect of
vibration of the ground causing vibration to the apparatus frame. Similarly, one
or more air mounts can be used to secure the components of the exposure apparatus
to the apparatus frame. Unfortunately, existing air mounts have a relatively high
lateral stiffness. Moreover, existing air mounts have a relatively large foot print
and require a significant amount of space.
In light of the above, there is a need for an exposure apparatus with an improved
isolation system. Additionally, there is a need for a vibration isolator having
relatively high lateral flexibility. Moreover, there is a need for a vibration
isolator having a relatively small footprint. Further, there is a need for an exposure
apparatus capable of manufacturing precision devices, such as high density, semiconductor wafers.
SUMMARY
The present invention is directed to a vibration isolator for isolating a first
assembly from vibration from a second assembly along a first axis. The vibration
isolator includes a housing that is secured to the second assembly, a pendulum
assembly that is coupled to the housing, and a mover. The pendulum assembly includes
a connector assembly, a sleeve, a first piston, a first piston seal and a pendulum
support. The first piston is secured to the first assembly and the connector assembly
flexibly connects the sleeve to the housing and allows the sleeve and first piston
to swing laterally relative to the first axis. The first piston seal flexibly seals
the first piston to the sleeve. Further, the pendulum support flexibly secures
the sleeve to the first piston. The pendulum support assists in supporting the
mass of the sleeve while allowing the first piston to move relative to the sleeve.
With this design, the vibration isolator has relatively good lateral damping.
In one embodiment, the first piston swings laterally relative to the first axis
along an arc shaped path during lateral movement of the first assembly. Further,
the first piston moves substantially parallel to the first axis.
In other embodiments, the vibration isolator includes a second piston and/or a
mover that is coupled to the first piston. With these designs, the vibration isolator
has a relatively small footprint and a relatively large capacity.
The vibration isolator is particularly useful as part of an exposure apparatus.
For example, one or more vibration isolators can be used as part of a frame isolation
system that secures a frame assembly of the exposure apparatus to a mounting base.
With this design, the frame isolation system reduces the effect of vibration of
the mounting base causing vibration on the frame assembly and the components that
are secured to the frame assembly.
Further, one or more of the vibration isolators can be used to secure one
or more other assemblies of the exposure apparatus to the frame assembly. For example,
one or more vibration isolators could be used as part of an isolation system to
secure a stage assembly or an optical assembly to the frame assembly.
The present invention is also directed to a device made with the exposure apparatus,
a wafer made with the exposure apparatus, a method for making a vibration isolator,
a method for making an isolation system, a method for making an exposure apparatus,
a method for making a device, and a method for making a wafer.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIG. 1 is a side illustration of an exposure apparatus having features of the
present invention;
FIG. 2A is a side view of a first embodiment of a vibration isolator having
features of the present invention;
FIG. 2B is a cut-away perspective view of the vibration isolator of FIG. 2A;
FIG. 2C is a side, cut-away illustration of the vibration isolator of FIG. 2A;
FIG. 3 is a side, cut-away illustration of another embodiment of a vibration
isolator having features of the present invention;
FIG. 4 is a side, cut-away illustration of yet another embodiment of a vibration
isolator having features of the present invention;
FIG. 5 is a side, cut-away illustration of still another embodiment of a vibration
isolator having features of the present invention;
FIG. 6A is a flow chart that outlines a process for manufacturing a device in
accordance with the present invention; and
FIG. 6B is a flow chart that outlines device processing in more detail.
DESCRIPTION
FIG. 1 illustrates an apparatus
10 that includes one or more isolation
assemblies
12 that isolate the apparatus
10 or a portion of the apparatus
10 from vibration. The type of apparatus
10 can be varied. For example,
the apparatus
10 can be used to manufacture, measure and/or inspect a device
14. The type of device
14 manufactured or inspected by the apparatus
10 can be varied. For example, the device
14 can be a semiconductor
wafer, and the isolation assemblies
12 can be used as part of an exposure
apparatus
10 that precisely transfers an image of an integrated circuit
from an object
16 such as a reticle onto the semiconductor wafer
14.
Some of the Figures provided herein include a coordinate system that designates
an X axis, a Y axis that is orthogonal to the X axis, and a Z axis that is orthogonal
to the X axis and the Y axis. It should be understood that the coordinate system
is merely for reference and can be varied. These axes are also referred to as a
first axis, a second axis, and a third axis.
The exposure apparatus
10 illustrated in FIG. 1 also includes a frame
assembly
18, an illumination system
20 (irradiation apparatus), a
reticle stage assembly
22, a projection optical assembly
24, a wafer
stage assembly
26, and a control system
28. The exposure apparatus
10 mounts to a mounting base
30, e.g., the ground, a base, or floor
or some other supporting structure.
There are a number of different types of exposure apparatuses
10. For
example, the exposure apparatus
10 can be used as scanning type photolithography
system that exposes the pattern from the reticle
16 onto the wafer
14
with the reticle
16 and the wafer
14 moving synchronously. In a scanning
type lithographic device, the reticle
16 is moved perpendicular to an optical
axis of the projection optical assembly
24 by the reticle stage assembly
22 and the wafer
14 is moved perpendicular to the optical axis of
the projection optical assembly
24 by the wafer stage assembly
26.
Scanning of the reticle
16 and the wafer
14 occurs while the reticle
16 and the wafer
14 are moving synchronously.
Alternately, the exposure apparatus
10 can be a step-and-repeat
type photolithography system that exposes the reticle
16 while the reticle
16 and the wafer
14 are stationary. In the step and repeat process,
the wafer
14 is in a constant position relative to the reticle
16
and the projection optical assembly
24 during the exposure of an individual
field. Subsequently, between consecutive exposure steps, the wafer stage assembly
26 consecutively moves the wafer
14 perpendicular to the optical
axis of the projection optical assembly
24 so that the next field of the
wafer
14 is brought into position relative to the projection optical assembly
24 and the reticle
16 for exposure. Following this process, the images
on the reticle
16 are sequentially exposed onto the fields of the wafer
14 so that the next field of the wafer
14 is brought into position
relative to the projection optical assembly
24 and the reticle
16.
However, the use of the exposure apparatus
10 and the isolation assemblies
12 is not limited to a photolithography system for semiconductor manufacturing.
The apparatus
10, 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 projection optical assembly. Additionally, the present invention provided
herein can be used in other devices, including other semiconductor processing equipment.
The frame assembly
18 is rigid and supports the components of the exposure
apparatus
10. The design of the frame assembly
18 can be varied to
suit the design requirements for the rest of the exposure apparatus
10.
The frame assembly
18 illustrated in FIG. 1 supports the projection optical
assembly
24, the illumination system
20, the reticle stage assembly
22 and the wafer stage assembly
26 above the mounting base
30.
The illumination system
20 includes an illumination source
32 and
an illumination optical assembly
34. The illumination source
32 emits
the beam (irradiation) of light energy. The illumination source
32 can be
g-line (436 nm), i-line (365 nm), KrF excimer laser (248 nm), ArF excimer laser
(193 nm) and F
2 laser (157 nm). Alternately, the illumination source
32 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
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.
The illumination optical assembly
34 guides the beam of light energy from
the illumination source
32 to the reticle
16. The beam illuminates
selectively different portions of the reticle
16 and exposes the semiconductor
wafer
14. In FIG. 1, the illumination source
32 is illustrated as
being supported above the reticle stage assembly
22. Typically, however,
the illumination source
32 is secured to one of the sides of the frame assembly
18 and the energy beam from the illumination source
32 is directed
to above the reticle
16 with the illumination optical assembly
34.
The reticle stage assembly
22 holds and positions the reticle
16
relative to the optical assembly
24 and the wafer
14. In FIG. 1,
the reticle stage assembly
22 includes a reticle stage base
38, a
reticle stage
40, and a reticle stage mover assembly
42. The reticle
stage base
38 supports the reticle stage
40 above the mounting base
30. The reticle stage
40 retains the reticle
16. A bearing
(not shown) allows for motion of the reticle stage
40 relative to the reticle
stage base
38. The reticle stage mover assembly
42 includes one or
more movers that move the reticle stage
40 relative to the reticle stage
base
38. As provided herein, each of the movers can include one or more
rotary motors, voice coil motors, linear motors, electromagnetic actuators, or
some other force actuators.
The reticle stage assembly
22 can include a reticle measurement system
(not shown) that monitors the position of the reticle stage
40 relative
to the projection optical assembly
24 or some other reference. For example,
the reticle measurement system can utilize laser interferometers, encoders, sensors,
and/or other measuring devices.
The projection optical assembly
24 projects, directs and/or focuses the
beam of light energy passing through the projection optical assembly
24.
The design of the projection optical assembly
24 can be varied according
to its design requirements. For example, the projection optical assembly
24
can magnify or reduce the image to be illuminated onto the device
14. The
projection optical assembly
24 need not be limited to a magnification or
a reduction system. The projection optical assembly
24 could also be a 1× system.
With respect to the projection optical assembly
24, 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
2
type laser or x-ray is used, the projection optical assembly
24 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.
Also, with an exposure device
10 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.
The wafer stage assembly
26 holds and positions the wafer
14 with
respect to the adjusted projected image of the illuminated portions of the reticle
16. In the embodiment illustrated in FIG. 1, the wafer stage assembly
26
includes a wafer stage base
52, a wafer stage
54, and a wafer stage
mover assembly
56. The wafer stage base
52 supports the wafer stage
54 above the mounting base
30. The wafer stage
54 retains
the wafer
14. A bearing such as an air bearing (not shown) allows for motion
of the wafer stage
54 relative to the wafer stage base
52. The wafer
stage mover assembly
56 includes one or more movers that move the wafer
stage
54 relative to the wafer stage base
52. As provided herein,
each of the movers can include one or more rotary motors, voice coil motors, linear
motors, electromagnetic actuators, or some other force actuators.
The wafer stage assembly
26 can include a wafer measurement system (not
shown) that monitors the position of the wafer stage
54 relative to the
projection optical assembly
24 or some other reference. For example, the
wafer measurement system can utilize laser interferometers, encoders, sensors,
and/or other measuring devices.
Further, in photolithography systems, when linear motors (see U.S. Pat.
No. 5,623,853 or U.S. Pat. No. 5,528,118) are used in a wafer stage assembly or
a reticle stage assembly, 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.
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.
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. 8-166475. 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.
Each isolation assembly
12 partly isolates a first assembly from vibration
of a second assembly along at least one axis. Stated another way, each isolation
assembly
12 inhibits vibration from the second assembly from being transferred
to the first assembly. In the embodiment illustrated in FIG. 1, the exposure apparatus
10 includes a frame stage isolation system
66, a reticle stage isolation
system
68, a wafer stage isolation system
70, and an optical isolation
system
72. The design of each isolation assembly
12 can be varied
to suit the design requirements of the apparatus
10.
In this embodiment, the frame isolation system
66 secures the frame assembly
18 to the mounting base
30. With this design, the frame isolation
system
66 reduces the effect of vibration of the mounting base
30
(the second assembly) causing vibration on the frame assembly
18 (the first
assembly) and the components of the exposure apparatus
10 that are secured
to the frame assembly
18. In this embodiment, the frame isolation system
66 includes a plurality of spaced apart vibration isolators
74 that
support the weight of the frame assembly
18, while allowing for movement
of the frame assembly
18 laterally relative to the mounting base
30.
The number of vibration isolators
74 in the frame isolation system
66
can be varied. For example, the frame isolation system
66 can include three
spaced apart vibration isolators
74.
Further, in this embodiment, the frame isolation system
66 moves
and positions the frame assembly
18 relative to the mounting base
30
base with six degrees of freedom. More specifically, the vibration isolators
74
adjust the position of the frame assembly
18 relative to the mounting base
30 along the Z axis, about the X axis and about the Y axis. Additionally,
the frame isolation system
66 includes one or more movers for adjusting
the position of the frame assembly
18 relative to the mounting base
30
along the X axis, along the Y axis and about the Z axis. In FIG. 1, the frame isolation
system
66 includes (i) two spaced apart X movers
82X that move the
frame assembly
18 relative to the mounting base
30 along the X axis
and about the Z axis, and (ii) a Y mover
82Y that moves the frame assembly
18 relative to the mounting base
30 along the Y axis.
The design of each mover
82X,
82Y can be varied to suit the movement
requirements of the apparatus
10. As provided herein, each of the movers
82X,
82Y can include one or more rotary motors, voice coil motors,
linear motors, electromagnetic actuators, or some other force actuators. In the
embodiment illustrated in FIG. 1, each of the movers
82X,
82Y is
a voice coil motor. Electrical current (not shown) is individually supplied to
each mover
82X,
82Y by the control system
28 to precisely
position the frame assembly
18.
In one embodiment, the control system
28 is connected to the vibration
isolators
74 and actively controls the vibration isolators
74 to
compensate for low frequency disturbances such as a shift in the center of gravity
in one of the stage assemblies
22,
26. Further, each vibration isolator
74 can include a Z mover (not shown) that moves the frame assembly
18
relative to the mounting base
30 along the Z axis and about the X axis and
Y axis. In this case, the Z mover may be disposed so that the drive force of the
Z mover and the support force (isolator axis) of the vibration isolator of the
present invention that will be explained hereinafter are on the same axis.
The position and acceleration of the frame assembly
18 relative to the
mounting base
30 can be monitored with one or more position and/or acceleration
sensors that are connected to the control system
28 (not shown). With information
from the sensors, the control system
28 can control the frame isolation
system
66 to adjust and control the position of the frame assembly
18
relative to the mounting base
30.
The reticle stage isolation system
68 secures and supports the reticle
stage base
38 to the frame assembly
18 and reduces the effect of
vibration of the frame assembly
18 (second assembly) causing vibration to
the reticle stage base
38 (first assembly). In this embodiment, the reticle
stage isolation system
68 includes a plurality of spaced apart vibration
isolators
76 that are connected to the control system
28 and support
the weight of the reticle stage base
38 and adjust the position of the reticle
stage base
38 with three degrees of freedom, while retaining relatively
low lateral and vertical stiffness for good passive vibration isolation of the
reticle stage base
38 relative to the frame assembly
18. Alternately,
the reticle stage isolation system
68 can be designed to move the reticle
stage base
38 with six degrees of freedom.
In this embodiment, the control system
28 actively controls the vibration
isolators
76 to compensate for low frequency disturbances to adjust the
static or low frequency position of the reticle stage base
38, to improve
vibration isolation by reducing the stiffness, and/or to compensate for a change
or shift in the center of gravity of the reticle stage assembly
22. In one
embodiment, the position and acceleration of the reticle stage base
38 can
be monitored with one or more position and/or acceleration sensors that are connected
to the control system
28 (not shown). With information from the sensors,
the control system
28 can cooperate with the reticle stage isolation system
68 to adjust and control the position of the reticle stage base
38.
The wafer stage isolation system
70 secures and supports the wafer stage
base
52 to the frame assembly
18 and reduces the effect of vibration
of the frame assembly
18 (second assembly) causing vibration to the wafer
stage base
52 (first assembly). The wafer stage isolation system
70
is similar to the reticle stage isolation system
68 discussed above. In
this embodiment, the wafer stage isolation system
70 includes a plurality
of spaced apart vibration isolators
78 connected to the control system
28
and the control system
28 actively controls vibration isolators
78
to adjust the static or low frequency position of the wafer stage base
52,
to adjust the position of the wafer stage base
52 with three degrees of
freedom and to improve vibration isolation by reducing the stiffness, and/or to
compensate for a change or shift in the center of gravity of the wafer stage assembly
26. Alternately, the wafer stage isolation system
70 can be designed
to move the wafer stage base
52 with six degrees of freedom. The position
and acceleration of the wafer stage base
52 can be monitored with one or
more position and/or acceleration sensors (not shown) that are connected to the
control system
28. With information from the sensors, the control system
28 can cooperate with the wafer stage isolation system
70 to adjust
and control the position of the wafer stage base
52.
The optical isolation system
72 secures and supports the projection optical
assembly
24 relative to the frame assembly
18 and reduces the effect
of vibration of the frame assembly
18 (second assembly) causing vibration
to the projection optical assembly
24 (first assembly). The optical isolation
system
72 is similar to the other isolation systems discussed above. In
this embodiment, the optical isolation system
72 includes a plurality of
spaced apart vibration isolators
80 connected to the control system
28
and the control system
28 actively controls vibration isolators
80
to position the optical assembly
24, to compensate for low frequency disturbances,
to adjust the static or low frequency position of the optical assembly
24
and to improve vibration isolation by reducing stiffness. The position and acceleration
of the projection optical assembly
24 can be monitored with one or more
position and/or acceleration sensors (not shown) that are connected to the control
system
28. With information from the sensors, the control system
28
can cooperate with the optical isolation system
72 to adjust and control
the position of the projection optical assembly
24.
FIG. 2A is a side view of one embodiment of a vibration isolator
200
that can be used in the isolation systems
66,
68,
70,
72
of FIG.
1. In this embodiment, the vibration isolator
200 isolates
a first assembly
202 from vibration from a second assembly
204 along
a first axis, e.g. the Z axis and transverse to the first axis. Stated another
way, the vibration isolator
200 attenuates vibration transmission from the
second assembly
204 to the first assembly
202. As provided herein,
the vibration isolator
200 can partly or substantially completely attenuate
vibration transmission.
FIG. 2B illustrates a cut-away perspective view of the vibration isolator
200,
the first assembly
202 and the second assembly
204 of FIG.
2A.
In this embodiment, the vibration isolator
200 includes a housing
206,
a pendulum assembly
208, and a fluid source
210. The design of these
components can be varied to suit the design requirements of the vibration isolator
200.
The housing
206 is secured to and couples the second assembly
204
to the vibration isolator
200. In FIG. 2B, the housing
206 includes
a housing bottom wall
216, a housing side wall
218, and a housing
top wall
220. In FIG. 2B, the housing bottom wall
216 is generally
disk shaped, is secured to the second assembly
204, and is positioned at
the bottom of the housing
206. The housing side wall
218 is generally
annular tube shaped and extends upward from the housing bottom wall
216.
The housing top wall
220 is generally annular disk shaped, is secured to
the top of the housing side wall
218, and extends inward from the housing
side wall
218.
The housing bottom wall
216 and the housing side wall
218 can be
formed as a unit and the housing top wall
220 can be secured and sealed
to the housing
