Title: Electromagnetic alignment and scanning apparatus
Abstract: In a scanning exposure method, a mask stage that holds a mask is moved in a scanning direction by a first electromagnetic driver having a first portion coupled to the mask stage, and a second portion. A position of the mask stage is detected by a position detector that cooperates with a reflective portion of the mask stage that is positioned along the scanning direction. A counter weight having a bearing and at least one beam extending along the scanning direction moves in a direction opposite to a movement direction of the mask stage in response to a reaction force generated by movement of the mask stage by the first electromagnetic driver. The counter weight preferably is heavier than the mask stage, and a length of the at least one beam along the scanning direction preferably is longer than a length of the reflective portion along the scanning direction.
Patent Number: 6,969,966 Issued on 11/29/2005 to Ebihara, et al.
| Inventors:
|
Ebihara; Akimitsu (Nishi kyo, JP);
Novak; Thomas (Hillsborough, CA)
|
| Assignee:
|
Nikon Corporation (Tokyo, JP)
|
| Appl. No.:
|
974787 |
| Filed:
|
October 28, 2004 |
Foreign Application Priority Data
| Current U.S. Class: |
318/649; 318/676; 414/935 |
| Intern'l Class: |
H01L 021/02.7 |
| Field of Search: |
318/560,566,640,646,648,649,671,676
414/935
|
References Cited [Referenced By]
U.S. Patent Documents
| RE27289 | Feb., 1972 | Sawyer.
| |
| RE27436 | Jul., 1972 | Sawyer.
| |
| 3789285 | Jan., 1974 | Nishizawa.
| |
| 3889164 | Jun., 1975 | Nishizawa et al.
| |
| 3935486 | Jan., 1976 | Nagashima.
| |
| 4019109 | Apr., 1977 | McCoy et al.
| |
| 4087729 | May., 1978 | Yamazaki et al.
| |
| 4129291 | Dec., 1978 | Kato et al.
| |
| 4234175 | Nov., 1980 | Sato et al.
| |
| 4392642 | Jul., 1983 | Chitayat.
| |
| 4409860 | Oct., 1983 | Moriyama et al.
| |
| 4425508 | Jan., 1984 | Lewis, Jr. et al.
| |
| 4443743 | Apr., 1984 | Forys et al.
| |
| 4485339 | Nov., 1984 | Trost.
| |
| 4492356 | Jan., 1985 | Taniguchi et al.
| |
| 4504144 | Mar., 1985 | Trost.
| |
| 4506204 | Mar., 1985 | Galburt.
| |
| 4506205 | Mar., 1985 | Trost et al.
| |
| 4507597 | Mar., 1985 | Trost.
| |
| 4514858 | Apr., 1985 | Novak.
| |
| 4516253 | May., 1985 | Novak.
| |
| 4525659 | Jun., 1985 | Imahashi et al.
| |
| 4575942 | Mar., 1986 | Moriyama.
| |
| 4615515 | Oct., 1986 | Suzuta et al.
| |
| 4628238 | Dec., 1986 | Smulders et al.
| |
| 4630942 | Dec., 1986 | Tsumaki et al.
| |
| 4641071 | Feb., 1987 | Tazawa et al.
| |
| 4648723 | Mar., 1987 | Sugiyama et al.
| |
| 4648724 | Mar., 1987 | Sugiyama et al.
| |
| 4653408 | Mar., 1987 | Nagashima et al.
| |
| 4654571 | Mar., 1987 | Hinds.
| |
| 4667139 | May., 1987 | Hirai et al.
| |
| 4675891 | Jun., 1987 | Plessis et al.
| |
| 4676492 | Jun., 1987 | Shamir.
| |
| 4677651 | Jun., 1987 | Hartl et al.
| |
| 4684315 | Aug., 1987 | Sugishima et al.
| |
| 4687980 | Aug., 1987 | Phillips et al.
| |
| 4698575 | Oct., 1987 | Bouwer.
| |
| 4708465 | Nov., 1987 | Isohata et al.
| |
| 4723086 | Feb., 1988 | Leibovich et al.
| |
| 4742286 | May., 1988 | Phillips.
| |
| 4744675 | May., 1988 | Sakino et al.
| |
| 4750721 | Jun., 1988 | Sasada.
| |
| 4770531 | Sep., 1988 | Tanaka et al.
| |
| 4803712 | Feb., 1989 | Kembo et al.
| |
| 4812725 | Mar., 1989 | Chitayat.
| |
| 4817930 | Apr., 1989 | Van Deuren.
| |
| 4870668 | Sep., 1989 | Frankel et al.
| |
| 4879482 | Nov., 1989 | Murofushi.
| |
| 4887804 | Dec., 1989 | Ohtsuka.
| |
| 4916340 | Apr., 1990 | Negishi.
| |
| 4952858 | Aug., 1990 | Galburt.
| |
| 4993696 | Feb., 1991 | Furukawa et al.
| |
| 5022619 | Jun., 1991 | Mamada.
| |
| 5031547 | Jul., 1991 | Hirose.
| |
| 5040431 | Aug., 1991 | Sakino et al.
| |
| 5059090 | Oct., 1991 | Bobroff et al.
| |
| 5120034 | Jun., 1992 | Van Engelen et al.
| |
| 5150153 | Sep., 1992 | Franken et al.
| |
| 5172160 | Dec., 1992 | Van Eijk et al.
| |
| 5194893 | Mar., 1993 | Nishi.
| |
| 5208497 | May., 1993 | Ishii et al.
| |
| 5228358 | Jul., 1993 | Sakino et al.
| |
| 5229670 | Jul., 1993 | Kagawa.
| |
| 5241183 | Aug., 1993 | Kanai et al.
| |
| 5243491 | Sep., 1993 | Van Eijk et al.
| |
| 5260580 | Nov., 1993 | Itoh et al.
| |
| 5280677 | Jan., 1994 | Kubo et al.
| |
| 5285142 | Feb., 1994 | Galburt et al.
| |
| 5315526 | May., 1994 | Maeda et al.
| |
| 5327060 | Jul., 1994 | Van Engelen et al.
| |
| 5338121 | Aug., 1994 | Kobayashi et al.
| |
| 5473410 | Dec., 1995 | Nishi.
| |
| 5477304 | Dec., 1995 | Nishi.
| |
| 5504407 | Apr., 1996 | Wakui et al.
| |
| 5528118 | Jun., 1996 | Lee.
| |
| 5715064 | Feb., 1998 | Lin.
| |
| 5721608 | Feb., 1998 | Taniguchi.
| |
| 5744924 | Apr., 1998 | Lee.
| |
| 5760564 | Jun., 1998 | Novak.
| |
| 5796469 | Aug., 1998 | Ebinuma.
| |
| 5801833 | Sep., 1998 | Kobayashi et al.
| |
| 6002465 | Dec., 1999 | Korenaga.
| |
| 6246204 | Jun., 2001 | Ebihara et al.
| |
| 6252370 | Jun., 2001 | Ebihara et al.
| |
| 6255795 | Jul., 2001 | Ebihara et al.
| |
| 6255796 | Jul., 2001 | Ebihara et al.
| |
| 6472840 | Oct., 2002 | Takahashi.
| |
| 6538719 | Mar., 2003 | Takahashi et al.
| |
| 6538720 | Mar., 2003 | Galburt et al.
| |
| 6717653 | Apr., 2004 | Iwamoto et al.
| |
| 6784978 | Aug., 2004 | Galburt.
| |
| Foreign Patent Documents |
| A1-0 502 578 | Nov., 1992 | EP.
| |
| 2 288 277 | Oct., 1995 | GB.
| |
| 61-45988 | Mar., 1986 | JP.
| |
| 63-20014 | Jan., 1988 | JP.
| |
| 3-21894 | Jan., 1991 | JP.
| |
Other References
Buckley, Jere D., et al. "Step and Scan: A Systems Overview of a New Lithography
Tool". The Perkin-Elmer Corporation, Connecticut Operations Sector, Norwalk, CT,
SPIE, vol. 1088, Laser Microlithography II (1989), pp. 424-433.
Moriyama, et al., "Precision X-Y Stage with a Piezo-driven Fine-table,"
The Bulletin of the Japan Society Precision Engineering, vol. 22, No. 1, pp. 13-17,
Mar. 1988.
SPIE vol. 135, Developments in Semiconductor Microlithography III (1978), "A
New VLSI Printer", Thomas W. Novak, pp. 36-43.
Cobilt Model CA-3400 Automatic Projection Mask Aligner User's Manual (1980).
Micrascan II Descriptions (1993).
SEMATECH Presentation (Jul. 1993).
|
Primary Examiner: Ro; Bentsu
Attorney, Agent or Firm: Oliff & Berridge PLC
Parent Case Text
This is a Division of application Ser. No. 10/397,366 filed Mar. 27, 2003 (now
U.S. Pat. No. 6,844,695), which in turn is a Division of application Ser. No. 09/977,292
filed Oct. 16, 2001 (now U.S. Pat. No. 6,693,402), which is a Division of application
Ser. No. 09/482,871 filed Jan. 14, 2000 (now U.S. Pat. No. 6,329,780), which is
a Division of application Ser. No. 09/260,544 filed Mar. 2, 1999 (now U.S. Pat.
No. 6,246,204), which is a Continuation-In-Part of application Ser. No. 08/698,827
filed Aug. 16, 1996 (abandoned), which is a Continuation of application Ser. No.
08/266,999 filed Jun. 27, 1994 (abandoned). The entire disclosures of the prior
applications are hereby incorporated by reference herein in their entireties.
Claims
1. A scanning exposure method that exposes a pattern of a mask onto an object,
the method comprising:
moving a mask stage that holds the mask in a scanning direction by a first electromagnetic
driver, the first electromagnetic driver having a first portion coupled to the
mask stage and a second portion;
detecting a position of the mask stage by a position detector that cooperates
with a reflective portion of the mask stage, the reflective portion being positioned
along the scanning direction;
moving a counter weight that comprises a bearing and at least one beam extending
along the scanning direction in a direction opposite to a movement direction of
the mask stage in response to a reaction force generated by a movement of the mask
stage by the first electromagnetic driver, the counter weight being heavier than
the mask stage, and a length of the at least one beam along the scanning direction
being longer than a length of the reflective portion along the scanning direction; and
projecting the pattern onto the object by a projection system, at least a portion
of the projection system being disposed vertically below the mask stage and the
counter weight.
2. The scanning exposure method of claim 1, wherein the position detector comprises
an interferometer system.
3. The scanning exposure method of claim 2, wherein the counter weight is movably
supported by a base via the bearing.
4. The scanning exposure method of claim 3, wherein the base movably supports
the mask stage.
5. The scanning exposure method of claim 3, wherein the at least one beam is
part of a frame having a rectangular shape.
6. The scanning exposure method of claim 3, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
7. The scanning exposure method of claim 3, further comprising:
moving the mask stage in a non-scanning direction different from the scanning
direction by a second electromagnetic driver coupled at least partly to the mask stage.
8. The scanning exposure method of claim 7, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
9. The scanning exposure method of claim 3, wherein the length of the reflective
portion along the scanning direction is longer than a stroke of the mask stage
along the scanning direction.
10. The scanning exposure method of claim 1, wherein the at least one beam is
part of a frame having a rectangular shape.
11. The scanning exposure method of claim 1, wherein the counter weight has a
frame shape.
12. The scanning exposure method of claim 1, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
13. The scanning exposure method of claim 1, further comprising:
moving the mask stage in a non-scanning direction different from the scanning
direction by a second electromagnetic driver coupled at least partly to the mask stage.
14. The scanning exposure method of claim 13, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
15. The scanning exposure method of claim 1, wherein the length of the reflective
portion along the scanning direction is longer than a stroke of the mask stage
along the scanning direction.
16. A stage operating method that moves a movable stage in a scanning direction,
the method comprising:
moving the movable stage in the scanning direction by a first electromagnetic
driver, the first electromagnetic driver having a first portion coupled to the
movable stage and a second portion;
detecting a position of the movable stage by a position detector that cooperates
with a reflective portion of the movable stage, the reflective portion being positioned
along the scanning direction; and
moving a counter weight that comprises a bearing and at least one beam extending
along the scanning direction in a direction opposite to a movement direction of
the movable stage in response to a reaction force generated by a movement of the
movable stage by the first electromagnetic driver, the counter weight being heavier
than the movable stage, and a length of the at least one beam along the scanning
direction being longer than a length of the reflective portion along the scanning direction.
17. The stage operating method of claim 16, wherein the position detector comprises
an interferometer system.
18. The stage operating method of claim 17, wherein the counter weight is movably
supported by a base via the bearing.
19. The stage operating method of claim 18, wherein the base movably supports
the movable stage.
20. The stage operating method of claim 18, wherein the at least one beam is
part of a frame having a rectangular shape.
21. The stage operating method of claim 18, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
22. The stage operating method of claim 18, further comprising:
moving the movable stage in a non-scanning direction different from the scanning
direction by a second electromagnetic driver coupled at least partly to the movable stage.
23. The stage operating method of claim 22, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
24. The stage operating method of claim 18, wherein the length of the reflective
portion along the scanning direction is longer than a stroke of the movable stage
along the scanning direction.
25. The stage operating method of claim 16, wherein the at least one beam is
part of a frame having a rectangular shape.
26. The stage operating method of claim 16, wherein the counter weight has a
frame shape.
27. The stage operating method of claim 16, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
28. The stage operating method of claim 16, further comprising:
moving the movable stage in a non-scanning direction different from the scanning
direction by a second electromagnetic driver coupled at least partly to the movable stage.
29. The stage operating method of claim 28, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
30. The stage operating method of claim 16, wherein the length of the reflective
portion along the scanning direction is longer than a stroke of the movable stage
along the scanning direction.
31. A scanning exposure method that exposes a pattern of a mask onto an object,
the method comprising:
moving a mask stage that holds the mask in a scanning direction by a first electromagnetic
driver that comprises a first portion coupled to the mask stage and a second portion;
moving the mask stage in a non-scanning direction different from the scanning
direction by a second electromagnetic driver, a moving distance of the mask stage
in the non-scanning direction by the second electromagnetic driver being shorter
than a moving distance of the mask stage in the scanning direction by the first
electromagnetic driver;
detecting a position of the mask stage by a position detector that cooperates
with a reflective portion of the mask stage, the reflective portion being positioned
along the scanning direction; and
moving a counter weight that comprises a bearing and at least one beam extending
along the scanning direction in a direction opposite to a movement direction of
the mask stage in response to a reaction force generated by a movement of the mask
stage by the first electromagnetic driver, the counter weight being heavier than
the mask stage, and the at least one beam being coupled to the second portion of
the first electromagnetic driver.
32. The scanning exposure method of claim 31, wherein a length of the at least
one beam along the scanning direction is longer than a length of the reflective
portion along the scanning direction.
33. The scanning exposure method of claim 32, wherein the length of the reflective
portion along the scanning direction is longer than a stroke of the mask stage
along the scanning direction.
34. The scanning exposure method of claim 32, wherein the counter weight is movably
supported by a base via the bearing.
35. The scanning exposure method of claim 34, wherein the base movably supports
the mask stage.
36. The scanning exposure method of claim 34, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
37. The scanning exposure method of claim 34, wherein the at least one beam is
part of a frame having a rectangular shape.
38. The scanning exposure method of claim 34, wherein the counter weight has
a frame shape.
39. The scanning exposure method of claim 38, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
40. The scanning exposure method of claim 31, wherein the at least one beam is
part of a frame having a rectangular shape.
41. The scanning exposure method of claim 31, wherein the counter weight has
a frame shape.
42. The scanning exposure method of claim 31, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
43. The scanning exposure method of claim 31, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
44. The scanning exposure method of claim 31, wherein a length of the reflective
portion along the scanning direction is longer than a stroke of the mask stage
along the scanning direction.
45. The scanning exposure method of claim 31, wherein the position detector comprises
an interferometer system.
46. A stage operating method that moves a movable stage in a scanning direction
and a non-scanning direction different from the scanning direction, the method comprising:
moving the movable stage in the scanning direction by a first electromagnetic
driver that comprises a first portion coupled to the movable stage and a second portion;
moving the movable stage in the non-scanning direction by a second electromagnetic
driver, a moving distance of the movable stage in the non-scanning direction by
the second electromagnetic driver being shorter than a moving distance of the movable
stage in the scanning direction by the first electromagnetic driver;
detecting a position of the movable stage by a position detector that cooperates
with a reflective portion of the movable stage, the reflective portion being positioned
along the scanning direction; and
moving a counter weight that comprises a bearing and at least one beam extending
along the scanning direction in a direction opposite to a movement direction of
the movable stage in response to a reaction force generated by a movement of the
movable stage by the first electromagnetic driver, the counter weight being heavier
than the movable stage, and the at least one beam being coupled to the second portion
of the first electromagnetic driver.
47. The stage operating method of claim 46, wherein a length of the at least
one beam along the scanning direction is longer than a length of the reflective
portion along the scanning direction.
48. The stage operating method of claim 47, wherein the length of the reflective
portion along the scanning direction is longer than a stroke of the movable stage
along the scanning direction.
49. The stage operating method of claim 47, wherein the counter weight is movably
supported by a base via the bearing.
50. The stage operating method of claim 49, wherein the base movably supports
the movable stage.
51. The stage operating method of claim 49, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
52. The stage operating method of claim 49, wherein the at least one beam is
part of a frame having a rectangular shape.
53. The stage operating method of claim 49, wherein the counter weight has a
frame shape.
54. The stage operating method of claim 53, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
55. The stage operating method of claim 46, wherein the at least one beam is
part of a frame having a rectangular shape.
56. The stage operating method of claim 46, wherein the counter weight has a
frame shape.
57. The stage operating method of claim 46, wherein the first electromagnetic
driver comprises a coil member and a magnet member.
58. The stage operating method of claim 46, wherein the second electromagnetic
driver comprises a coil member and a magnet member.
59. The stage operating method of claim 46, wherein a length of the reflective
portion along the scanning direction is longer than a stroke of the movable stage
along the scanning direction.
60. The stage operating method of claim 46, wherein the position detector comprises
an interferometer system.
Description
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a movable stage apparatus capable of precise
movement, and particularly relates to a stage apparatus movable in one linear direction
capable of high accuracy positioning and high speed movement, which can be especially
favorably utilized in a microlithographic system. This invention also relates to
an exposure apparatus that is used for the transfer of a mask pattern onto a photosensitive
substrate during a lithographic process to manufacture, for example, a semiconductor
element, a liquid crystal display element, a thin film magnetic head, or the like.
2. Description of Related Art
When a semiconductor element or the like is manufactured, a projection exposure
apparatus is used that transfers an image of a pattern of a reticle, used as a
mask, onto each shooting area on a wafer (or a glass plate or the like) on which
a resist is coated, used as a substrate, through a projection optical system. Conventionally,
as a projection exposure apparatus, a step-and-repeat type (batch exposure type)
projection exposure apparatus (stepper) has been widely used. However, a scanning
exposure type projection exposure apparatus (a scanning type exposure apparatus),
such as a step-and-scan type, which performs an exposure as a reticle and a wafer
are synchronously scanned with respect to a projection optical system, has attracted attention.
In a conventional exposure apparatus, a reticle stage, which supports and carries
the reticle, which is the original pattern, and the wafer to which the pattern
is to be transferred, and the driving part of the wafer stage are fixed to a structural
body that supports a projection optical system. The vicinity of the center of gravity
of the projection optical system is also fixed to the structural body. Additionally,
in order to position a wafer stage with high accuracy, the position of the wafer
stage is measured by a laser interferometer, and a moving mirror for the laser
interferometer is fixed to the wafer stage.
Furthermore, in order to carry a wafer to a wafer holder on the wafer
stage, a wafer carrier arm that takes out a wafer from a wafer cassette and carries
it to the wafer holder, and a wafer carrier arm that carries the wafer from the
wafer holder to the wafer cassette, are independently provided. When the wafer
is carried in, the wafer that has been carried by the wafer carrier arm is temporarily
fixed to and supported by a special support member that can be freely raised and
lowered and that is provided on the wafer holder. Thereafter, the carrier arm is
withdrawn, the support member is lowered, and the wafer is disposed on the wafer
holder. After this, the wafer is vacuum absorbed to the top of the wafer holder.
When the wafer is carried out from the exposure device, the opposite operation
is performed.
As described above, in the conventional exposure apparatus, the driving part
of
the wafer stage or the like and the projection optical system are fixed to the
same structural body. Thus, the vibration generated by the driving reaction of
the stage is transmitted to the structural body, and the vibration is also transmitted
to the projection optical system. Furthermore, all the mechanical structures were
mechanically resonate to a vibration of a predetermined frequency, so there are
disadvantages such that deformation of the structural body and the resonance phenomenon
occurred, and position shifting of a transfer pattern image and deterioration of
contrast occurred when this type of vibration is transmitted to the structural body.
Furthermore, because the wafer stage moves over a long distance from
the carrier arm for carrying in and out of the wafer to the exposure position,
it is necessary to provide an extremely long moving mirror for the laser interferometer.
Because of this, the weight of the wafer stage becomes relatively heavy and the
driving reaction becomes large because a heavy motor with a large driving force
is needed. Furthermore, in order to improve throughput, when the moving speed and
acceleration of the stage needs to be increased, the driving reaction becomes even
larger. In addition, as the weight and acceleration of the stage increase, the
heating amount of the motor increases, and there is a disadvantage such that measurement
stability or the like of the laser interferometer deteriorates.
Furthermore, in the case of carrying the wafer into and out of the exposure
apparatus, the wafer is temporarily fixed and supported on the top of a special
support member, so carrying in and out of the wafer consumes time. This causes
deterioration of throughput. Additionally, as one example, because giving and receiving
of the wafer is performed between the carrier arms, the probability of the wafer
being contaminated is high, and the probability of having an operation error when
the wafer was given and received is high. Furthermore, the number of carrier arms
is a major point governing the size of the carrier unit, so the carrier path becomes
long when giving and receiving of the wafer is performed between the carrier arms
on the carrier path. Additionally, a floor area (foot print) that is needed for
the exposure apparatus also becomes large.
In wafer steppers, the alignment of an exposure field to the reticle being imaged
affects the success of the circuit of that field. In a scanning exposure system,
the reticle and wafer are moved simultaneously and scanned across one another during
the exposure sequence.
To attain high accuracy, the stage should be isolated from mechanical disturbances.
This is achieved by employing electromagnetic forces to position and move the stage.
It should also have high control bandwidth, which requires that the stage be a
light structure with no moving parts. Furthermore, the stage should be free from
excessive heat generation which might cause interferometer interference or mechanical
changes that compromise alignment accuracy.
Commutatorless electromagnetic alignment apparatus such as the ones
disclosed in U.S. Pat. Nos. 4,506,204, 4,506,205 and 4,507,597 are not feasible
because they require the manufacture of large magnet and coil assemblies that are
not commercially available. The weight of the stage and the heat generated also
render these designs inappropriate for high accuracy applications.
An improvement over these commutatorless apparatus was disclosed in U.S. Pat.
No. 4,592,858, which employs a conventional XY mechanically guided sub-stage to
provide the large displacement motion in a plane, thereby eliminating the need
for large magnet and coil assemblies. The electromagnetic means mounted on the
sub-stage isolates the stage from mechanical disturbances. Nevertheless, the combined
weight of the sub-stage and stage still results in low control bandwidth, and the
heat generated by the electromagnetic elements supporting the stage is still substantial.
Even though the current apparatus using commutated electromagnetic means is
a significant improvement over prior commutatorless apparatus, the problems of
low control bandwidth and interferometer interference persist. In such an apparatus,
a sub-stage is moved magnetically in one linear direction and the commutated electromagnetic
means mounted on the sub-stage in turn moves the stage in the normal direction.
The sub-stage is heavy because it carries the magnet tracks to move the stage.
Moreover, heat dissipation on the stage compromises interferometer accuracy.
It is also well known to move a movable member (stage) in one long linear direction
(e.g. more than 10 cm) by using two of the linear motors in parallel where coil
and magnet are combined. In this case, the stage is guided by some sort of a linear
guiding member and driven in one linear direction by a linear motor installed parallel
to the guiding member. When driving the stage only to the extent of extremely small
stroke, the guideless structure based on the combination of several electromagnetic
actuators, as disclosed in the prior art mentioned before, can be adopted. However,
in order to move the guideless stage by a long distance in one linear direction,
a specially structured electromagnetic actuator as in the prior art becomes necessary,
causing the size of the apparatus to become larger, and as a result, generating
a problem of consuming more electricity.
SUMMARY OF THE INVENTION
It is an object of the present invention to make it possible for a guideless
stage
to move with a long linear motion using electromagnetic force, and to provide a
light weight apparatus in which low inertia and high response are achieved.
It is another object of the present invention to provide a guideless stage apparatus
using commercially available regular linear motors as electromagnetic actuators
for one linear direction motion.
It is another object of the present invention to provide a guideless stage apparatus
capable of active and precise position control for small displacements without
any contact in the direction orthogonal to the long linear motion direction.
It is another object of the present invention to provide a completely non-contact
stage apparatus by providing a movable member (stage body) that moves in one linear
direction and a second movable member that moves sequentially in the same direction,
constantly keeping a certain space therebetween, and providing the electromagnetic
force (action and reaction forces) in the direction orthogonal to the linear direction
between this second movable member and the stage body.
It is another object of the present invention to provide a non-contact stage
apparatus
capable of preventing the positioning and running accuracy from deteriorating by
changing tension of various cables and tubes to be connected to the non-contact
stage body that moves as it supports an object.
It is another object of the present invention to provide a non-contact apparatus
that is short in its height, by arranging the first movable member and the second
movable member in parallel, which move in the opposite linear direction to one another.
It is another object of the present invention to provide an apparatus that is
structured so as not to change the location of the center of gravity of the entire
apparatus even when the non-contact stage body moves in one linear direction.
Another object of this invention is to provide an exposure apparatus that
can perform an exposure with high accuracy by reducing the effects of vibration
on a projection optical system or the like that occurs when the wafer stage or
the like is driven.
Another object of this invention is to provide an exposure apparatus that
suppresses the amount of heat generated by the driving part of the wafer stage,
to perform positioning of the driving part of the wafer stage with high accuracy,
and to maintain the measurement stability of a position measurement device or the like.
Another object of this invention is to provide an exposure apparatus with
high throughput that can carry a wafer to an exposure apparatus without temporarily
fixing the wafer, and without giving and receiving of the wafer between wafer carrier arms.
In order to achieve the above and other objects, embodiments of the present invention
may be constructed as follows.
An apparatus that is capable of high accuracy position and motion control utilizes
linear commutated motors to move a guideless stage in one long linear direction
and to create small yaw rotation in a plane. A carrier/follower holding a single
voice coil motor (VCM) is controlled to approximately follow the stage in the direction
of the long linear motion. The VCM provides an electromagnetic force to move the
stage for small displacements in the plane in a linear direction perpendicular
to the direction of the long linear motion to ensure proper alignment. This follower
design eliminates the problem of cable drag for the stage since the cables connected
to the stage follow the stage via the carrier/follower. Cables connecting the carrier/follower
to external devices will have a certain amount of drag, but the stage is free from
such disturbances because the VCM on the carrier/follower acts as a buffer by preventing
the transmission of mechanical disturbances to the stage.
According to one aspect of the invention, the linear commutated motors
are located on opposite sides of the stage and are mounted on a driving frame.
Each linear commutated motor includes a coil member and a magnetic member, one
of which is mounted on one of the opposed sides of the stage, and the other of
which is mounted on the driving frame. Both motors drive in the same direction.
By driving the motors slightly different amounts, small yaw rotation of the stage
is produced.
In accordance with another aspect of the present invention, a moving counter-weight
is provided to preserve the location of the center of gravity of the stage system
during any stage motion by using the conservation of momentum principle. In an
embodiment of the present invention, the drive frame carrying one member of each
of the linear motors is suspended above the base structure, and when the drive
assembly applies an action force to the stage to move the stage in one direction
over the base structure, the driving frame moves in the opposite direction in response
to the reaction force to substantially maintain the center of gravity of the apparatus.
This apparatus essentially eliminates any reaction forces between the stage system
and the base structure on which the stage system is mounted, thereby facilitating
high acceleration while minimizing vibrational effects on the system.
By restricting the stage motion to the three specified degrees of freedom, the
apparatus is simple. By using electromagnetic components that are commercially
available, the apparatus design is easily adaptable to changes in the size of the
stage. This high accuracy positioning apparatus is ideally suited for use as a
reticle scanner in a scanning exposure system by providing smooth and precise scanning
motion in one linear direction and ensuring accurate alignment by controlling small
displacement motion perpendicular to the scanning direction and small yaw rotation
in the scanning plane.
An exposure apparatus according to another aspect of this invention includes a
projection optical system support member that supports a projection optical system,
so that the projection optical system rotates within a specified area, taking a
reference point as a center. Therefore, even if vibration from a substrate stage
and a mask stage is transmitted to the projection optical system, the position
relationship between the object plane (mask) and the image plane (substrate) is
not shifted. Thus, it is possible to prevent position shifting of the pattern to
be transferred, and highly accurate exposure can be performed.
Furthermore, a mask stage that moves a mask, a structural body that
supports this mask stage and the projection optical system, and a substrate stage
that moves a substrate are provided. The projection optical system support part
(the structural body) has at least three flexible support members extending from
the structural body, and the extending lines of each support member cross at the
reference point. In this case, even if vibration is transmitted to the projection
optical system, the projection optical system is minutely rotated taking the reference
point as a center. Therefore, it is possible to prevent position shifting of the
pattern to be transferred to the substrate. Furthermore, the support members are
flexible, so the minute vibration can be reduced and the deterioration of contrast
of a pattern to be formed can be prevented.
An exposure apparatus according to another aspect of this invention controls
the
mask base so that the mask base moves at a specified speed in a direction opposite
to the moving direction of the mask stage. This reduces the effects to the structural
body of the driving reaction of the mask stage. Additionally, the excitation of
mechanical resonance is controlled, and the vibration transmitted to the structural
body and the projection optical system can be reduced. Therefore, exposure with
a high accuracy can be performed.
In an exposure apparatus according to another aspect of this invention, by having
an elastic member at both ends of a guide axis, when the substrate table performs
constant velocity reciprocation on the guide axis, the kinetic energy of the substrate
table is converted to potential energy and is stored in the elastic members. Therefore,
the energy to be consumed when the substrate table is reciprocated at constant
velocity is mainly only the energy to be consumed in the viscosity resistance of
the substrate table with respect to air. The only heat generated is the heat from
when the elastic members are deformed. Therefore, it is possible to control the
heating amount of the driving part when the substrate table moves at constant velocity.
Furthermore, when the elastic member has first magnetic members disposed
at both ends of the guide axis and second magnetic members disposed corresponding
to the first magnetic members, by the attraction of the first and second magnetic
members, when the substrate table is still-positioned at an end of the guide axis,
it is possible to reduce the thrust of the driving part of the substrate table
required to oppose the resistance of the elastic member. Thus, the heating amount
of the driving part can be controlled when the substrate table is still-positioned.
In an exposure apparatus according to another aspect of this invention, by controlling
the length of the support legs that can be freely exte
