U.S. patent number RE40,043 [Application Number 10/347,491] was granted by the patent office on 2008-02-05 for positioning device having two object holders.
This patent grant is currently assigned to ASML Netherlands B.V.. Invention is credited to Gerrit Maarten Bonnema, Yim-Bun Patrick Kwan, Erik Roelof Loopstra, Harmen Klaas Van Der Schoot, Gerjan Peter Veldhuis.
United States Patent |
RE40,043 |
Kwan , et al. |
February 5, 2008 |
Positioning device having two object holders
Abstract
A positioning device has first and second object holders that
are guided over a guiding surface extending parallel to an
X-direction and parallel to a Y-direction perpendicular to the
X-direction and which are displaceable over the guiding surface
from a first position into a second position by means of a
displacement system. The displacement system includes a first
displacement unit and a second displacement unit to which the
object holders can be alternately coupled. The first displacement
unit is suitable for carrying out a first series of positioning
steps of the first object holder in the first position and for
displacing the first object holder from the first position into an
intermediate position between the first and second positions. The
second displacement unit is suitable for carrying out a second
series of positioning steps of the second object holder in the
second position, simultaneously with and independently of the first
displacement unit, and for displacing the second object holder from
the second position into the intermediate position. In the
intermediate position, the object holders are exchanged, after
which the first series of positioning steps can be carried out by
the first displacement unit with the second object holder in the
first position and the second series of positioning steps can be
carried out by the second displacement unit with the first object
holder in the second position. The positioning device is suitable
for use in a lithographic device to carry out an exposure process
with a first semiconductor substrate in an exposure position and,
simultaneously therewith and independently thereof, a
characterization process with a second semiconductor substrate in a
characterization position.
Inventors: |
Kwan; Yim-Bun Patrick (Aalen,
DE), Bonnema; Gerrit Maarten (Hengelo, NL),
Loopstra; Erik Roelof (Heeze, NL), Van Der Schoot;
Harmen Klaas (Vught, NL), Veldhuis; Gerjan Peter
(Vinkel, NL) |
Assignee: |
ASML Netherlands B.V.
(Veldhoven, NL)
|
Family
ID: |
8228087 |
Appl.
No.: |
10/347,491 |
Filed: |
February 27, 1998 |
PCT
Filed: |
February 27, 1998 |
PCT No.: |
PCT/IB98/00254 |
371(c)(1),(2),(4) Date: |
October 29, 1998 |
PCT
Pub. No.: |
WO98/40791 |
PCT
Pub. Date: |
September 17, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09180011 |
Oct 29, 1998 |
06262796 |
Jul 17, 2001 |
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Foreign Application Priority Data
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Mar 10, 1997 [EP] |
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97200706 |
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Current U.S.
Class: |
355/53;
356/401 |
Current CPC
Class: |
B23Q
11/0032 (20130101); G03F 7/7075 (20130101); B23Q
1/621 (20130101); G03F 7/70716 (20130101); G03F
7/70741 (20130101); G03F 7/70733 (20130101); G03F
7/709 (20130101); B23Q 1/623 (20130101); H01L
21/682 (20130101) |
Current International
Class: |
G03B
27/42 (20060101); G03B 11/00 (20060101) |
Field of
Search: |
;355/53,55,75,72
;356/399,400,401 ;396/624,611 ;310/12 ;318/687 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 498 496 |
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Aug 1992 |
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EP |
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0 525 872 |
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Feb 1993 |
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EP |
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0 687 957 |
|
Dec 1995 |
|
EP |
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2 155 201 |
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Sep 1985 |
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GB |
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2 290 658 |
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Jan 1996 |
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GB |
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3-273607 |
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Dec 1991 |
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JP |
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Primary Examiner: Kim; Peter B.
Attorney, Agent or Firm: Pillsbury Winthrop Shaw Pittman
LLP
Claims
What is claimed is:
1. A positioning device for a lithographic apparatus, comprising: a
guiding surface extending parallel to an X-direction and parallel
to a Y-direction; a first object holder and a second object holder
which are each adapted to be guided over the guiding surface and
are each displaceable parallel to the X-direction and parallel to
the Y-direction from a first position into a second position; and a
displacement system constructed and arranged to displace the first
object holder and the second object holder over the guiding
surface, wherein the displacement system comprises a first
displacement unit and a second displacement unit to which the first
object holder, and the second object holder can be coupled
alternately, the first displacement unit being suitable for
displacing the object holders from the first position into an
intermediate position between the first position and the second
position, and the second displacement unit being suitable for
displacing the object holders from the intermediate position into
the second position.
2. A positioning device as claimed in claim 1, wherein the first
and second displacement units each comprise an X-motor having a
first part extending parallel to the X-direction and a second part
which is displaceable along the first part of the X-motor and can
be coupled alternately to the first object holder and to the second
object holder, and two Y-motors each having a first part extending
parallel to the Y-direction and a second part which is displaceable
along the first part of the relevant Y-motor, the first part of the
X-motor of each displacement unit being connected to the second
parts of the two Y-motors of the relevant displacement unit.
3. A positioning device as claimed in claim 2, wherein the first
parts of the Y-motors of the two displacement units are connected
to a common balancing unit which is guided relative to a base of
the positioning device so as to be displaceable parallel to the
X-direction and parallel to the Y-direction and to be rotatable
about an axis of rotation extending perpendicularly to the
X-direction and the Y-direction.
4. A positioning device as claimed in claim 1, wherein the object
holder each comprise a basic part which is guided over the guiding
surface and adapted to be coupled to the displacement units, and an
object table which is displaceable relative to the basic part by an
actuator unit of the relevant object holder.
5. A positioning device as claimed in claim 4, wherein the object
table of each of the object holders is displaceable relative to the
basic part parallel to the X-direction, parallel to the
Y-direction, and parallel to a Z-direction extending
perpendicularly to the X-direction and the Y-direction, and is
pivotable relative to the basic part about a first pivot axis
extending parallel to the X-direction, a second pivot axis
extending parallel to the Y-direction, and a third pivot axis
extending parallel to the Z-direction.
6. A positioned device as claimed in claim 1, wherein said first
and second object holders are first and second substrate holders,
respectively.
7. A lithographic device comprising: a radiation source; a mask
.[.bolder.]. .Iadd.holder.Iaddend.; a focusing unit having a main
axis; a characterization unit; and a positioning device comprising:
a guiding surface extending parallel to an X-direction, which is
perpendicular to the main axis, and parallel to a Y-direction,
which is perpendicular to the X-direction and this main axis, a
first substrate holder and a second substrate holder which are each
guided over the guiding surface and are each displaceable parallel
to the X-direction and parallel to the Y-direction from a first
position into a second position which is near the focusing unit,
and a displacement system constructed and arranged to displace the
first substrate .[.bolder.]. .Iadd.holder .Iaddend.and the second
substrate holder over the guiding surface, wherein the displacement
system comprises a first displacement unit and a second
displacement unit to which the first substrate holder and second
substrate holder can be coupled alternately, the first displacement
unit being suitable for displacing the substrate holders from the
first position into an intermediate position between the first
position and the second position, and the second displacement unit
being suitable for displacing the substrate holders from the
intermediate position into the second position, and wherein the
first position of the substrate holders is a characterization
position which is present near the characterization unit.
8. A lithographic device as claimed in claim 7, wherein the first
and second displacement units each comprise an X-motor having a
first part extending parallel to the X-direction and a second part
which is displaceable along the first part of the X-motor and can
be coupled alternately to the first substrate holder and to the
second substrate holder, and two Y-motors each having a first part
extending parallel to the Y-direction and a second part which is
displaceable along the first part of the relevant Y-motor, the
first part of the X-motor of each displacement unit being connected
to the second parts of the two Y-motors of the relevant
displacement unit.
9. A lithographic device as claimed in claim 8, wherein the first
parts of the Y-motors of the two displacement units are connected
to a common balancing unit which is guided relative to a base of
the positioning device so as to be displaceable parallel to the
X-direction and parallel to the Y-direction and to be rotatable
about an axis of rotation extending perpendicularly to the
X-direction and the Y-direction.
10. A lithographic device as claimed in claim 7, wherein the
substrate holders each comprise a basic part which is guided over
the guiding surface and can be coupled to the displacement units,
and a substrate table which is displaceable relative to the basic
part by means of an actuator unit of the relevant substrate
holder.
11. A lithographic device as claimed in claim 10, wherein the
substrate table of each of the substrate holders is displaceable
relative to the basic part parallel to the X-direction, parallel to
the Y-direction, and parallel to the Z-direction extending
perpendicularly to the X-direction and the Y-direction, and is
pivotable relative to the basic part about a first pivot axis
extending parallel to the X-direction, a second pivot axis
extending parallel to the Y-direction, and a third pivot axis
extending parallel to the Z-direction.
.Iadd.12. A positioning device for a lithographic apparatus,
comprising: a guiding surface extending parallel to an X-direction
and parallel to a Y-direction; a first object holder and a second
object holder which are each adapted to be guided over the guiding
surface and are each displaceable parallel to the X-direction and
parallel to the Y-direction from a first position into a second
position; a displacement system constructed and arranged to
displace the first object holder and the second object holder over
the guiding surface; wherein the displacement system comprises a
first displacement unit and a second displacement unit to which the
first object holder and the second object holder can be coupled
alternately so that the first object holder and the second object
holder switch positions; wherein the first and second displacement
units each comprise an X-motor having a first part extending
parallel to the X-direction and a second part which is displaceable
along the first part of the X-motor and can be coupled alternately
to the first object holder and to the second object holder, and two
Y-motors each having a first part extending parallel to the
Y-direction and a second part which is displaceable along the first
part of the relevant Y-motor, the first part of the X-motor of each
displacement unit being connected to the second parts of the two
Y-motors of the relevant displacement unit; and wherein the first
parts of the Y-motors of the two displacement units are connected
to a common balancing unit which is guided relative to a base of
the positioning device so as to be displaceable parallel to the
X-direction and parallel to the Y-direction and to be rotatable
about an axis of rotation extending perpendicularly to the
X-direction and the Y-direction..Iaddend.
.Iadd.13. A positioning device for a lithographic apparatus,
comprising: a guiding surface extending parallel to an X-direction
and parallel to a Y-direction; a first object holder and a second
object holder which are each adapted to be guided over the guiding
surface and are each displaceable parallel to the X-direction and
parallel to the Y-direction from a first position into a second
position; a displacement system constructed and arranged to
displace the first object holder and the second object holder over
the guiding surface; wherein the displacement system comprises a
first displacement unit and a second displacement unit to which the
first object holder and the second object holder can be coupled
alternately so that the first object holder and the second object
holder switch positions; wherein the object holders each comprise a
basic part which is guided over the guiding surface and adapted to
be coupled to the displacement units, and an object table which is
displaceable relative to the basic part by an actuator unit of the
relevant object holder; and wherein the object table of each of the
object holders is displaceable relative to the basic part parallel
to the X-direction, parallel to the Y-direction, and parallel to a
Z-direction extending perpendicularly to the X-direction and the
Y-direction, and is pivotable relative to the basic part about a
first pivot axis extending parallel to the X-direction, a second
pivot axis extending parallel to the Y-direction, and a third pivot
axis extending parallel to the Z-direction..Iaddend.
.Iadd.14. A positioning device for a lithographic apparatus,
comprising: a guiding surface extending parallel to an X-direction
and parallel to a Y-direction; a first object holder and a second
object holder which are each adapted to be guided over the guiding
surface and are each displaceable parallel to the X-direction and
parallel to the Y-direction from a first position into a second
position; a displacement system constructed and arranged to
displace the first object holder and the second object holder over
the guiding surface; wherein the displacement system comprises a
first displacement unit and a second displacement unit to which the
first object holder and the second object holder can be coupled
alternately so that the first object holder and the second object
holder switch positions; and wherein said first and second object
holders are first and second substrate holders,
respectively..Iaddend.
.Iadd.15. A positioning method for performing operations on
substrates in a lithographic device, comprising: moving first and
second substrate holders over a two-dimensional plane between a
first position into a second position with first and second
displacement units; loading and characterizing a substrate in the
first position; exposing and unloading the substrate in the second
position; the first and second displacement units moving the first
substrate holder and the second substrate holder over the guiding
surface between the first and second positions using connections
that can be coupled and uncoupled so that the substrate holders
switch positions..Iaddend.
Description
BACKGROUND OF THE INVENTION
The invention relates to a positioning device having a guiding
surface extending parallel to an X-direction and parallel to a
Y-direction, a first object holder and a second object holder which
are each guided over the guiding surface and are each displaceable
parallel to the X-direction and parallel to the Y-direction from a
first position into a second position, and a displacement system
for displacing the first object holder and the second object holder
over the guiding surface.
The invention further relates to a lithographic device provided
with a radiation source, a mask holder, a focusing unit having a
main axis, a characterization unit, and a positioning device, said
positioning device comprising a guiding surface extending parallel
to an X-direction, which is perpendicular to the main axis, and
parallel to a Y-direction, which is perpendicular to the
X-direction and the main axis, a first substrate holder and a
second substrate holder which are each guided over the guiding
surface and are each displaceable parallel to the X-direction and
parallel to the Y-direction from a first position into a second
position which is present near the focusing unit, and a
displacement system for displacing the first substrate holder and
the second substrate holder over the guiding surface.
A positioning device and a lithographic device of the kinds
mentioned in the opening paragraphs are known from EP-A-0 687 957.
The known lithographic device is used for the exposure of
semiconductor substrates in the manufacturing process of integrated
semiconductor circuits and operates according to the so-called
step-and-repeat process. The known positioning device is used in
the known lithographic device for displacing semiconductor
substrates relative to the focusing unit and relative to the
characterization unit. The first position of the known positioning
device is a load and unload position in which a semiconductor
substrate can be loaded on or unloaded from the first or the second
object holder. The second position of the positioning device is an
exposure position in which a semiconductor substrate present on the
first or the second object holder can be exposed via the focusing
unit. The first and the second object holder are displaceable from
the first position to the second position and vice versa by the
displacement system of the positioning device which is not
described in detail in EP-A-0 687 957. When the first object holder
is in the second position and the semiconductor substrate present
thereon is being exposed, the second object holder is in the first
position and a next semiconductor substrate is loaded thereon at
first. Then the second object holder is displaced from the first
position to a characterization position in which the semiconductor
substrate present on the second object holder is characterized by
the characterization unit. When the second object holder is in the
characterization position, the first object holder and the second
object holder are displaced lockstep-wise. In this manner the
exposure of the semiconductor substrate present on the first object
holder and the characterization of the semiconductor substrate
present on the second object holder are carried out simultaneously,
so that a high throughput of the step-and-repeat apparatus is
obtained.
A disadvantage of the known positioning device and the known
lithographic device is that the characterization of the
semiconductor substrate present on the second object holder and the
exposure of the semiconductor substrate present on the first object
holder cannot be carried out independently from each other as a
result of said lockstep-wise displacements of the first and the
second object holder. As a result, the exposure of the
semiconductor substrate present on the first object holder cannot
be started until the second object holder has reached the
characterization position.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a positioning
device of the kind mentioned in the opening paragraph in which a
first process involving a first series of positioning steps of the
first object holder can be carried out simultaneously with and
independently from a second process involving a second series of
positioning steps of the second object holder, and in which also
the first process can be carried out with the second object holder
and, simultaneously and independently, the second process can be
carried out with the first object holder.
It is a further object of the present invention to provide a
lithographic device of the kind mentioned in the second paragraph
in which a characterization process involving a first series of
positioning steps of the first substrate holder can be carried out
simultaneously with and independently from an exposure process
involving a second series of positioning steps of the second
substrate holder, and in which also the characterization process
can be carried out with the second substrate holder and,
simultaneously and independently, the exposure process can be
carried out with the first substrate holder.
The positioning device according to the invention is for this
purpose characterized in that the displacement system comprises a
first displacement unit and a second displacement unit to which the
first object holder and the second object holder can be coupled
alternately, the first displacement unit being suitable for
displacing the object holders from the first position into an
intermediate position between the first position and the second
position, and the second displacement unit being suitable for
displacing the object holders from the intermediate position into
the second position. As a result of the use of said first and
second displacement units, a first process involving a first series
of positioning steps of the first object holder can be carried out
in the first position by means of the first displacement unit, and
a second process involving a second series of positioning steps of
the second object holder can be carried out in the second position
by means of the second displacement unit simultaneously with and
independently from the first process. When the first process and
the second process have been completed, the first object holder is
displaced by the first displacement unit from the first position
into the intermediate position and the second object holder is
displaced by the second displacement unit from the second position
into the intermediate position. In the intermediate position, the
first object holder is uncoupled from the first displacement unit
and is coupled to the second displacement unit, while the second
object holder is uncoupled from the second displacement unit and is
coupled to the first displacement unit. Subsequently, the first
object holder is displaced by the second displacement unit from the
intermediate position to the second position and the second object
holder is displaced by the first displacement unit from the
intermediate position to the first position. Then the first process
can be carried out with the second object holder in the first
position and, simultaneously and independently, the second process
can be carried out with the first object holder in the second
position. Furthermore, as a result of the use of said two
displacement units, a distance over which each individual
displacement unit has to displace the object holders is reduced, so
that the required dimensions of the displacement units are reduced.
It is in addition prevented that the displaceable parts of the
first displacement unit and the displaceable parts of the second
displacement unit must be constructed so as to be capable of
passing one another, which allows a comparatively simple
construction of the displacement units.
The lithographic device according to the invention is for this
purpose characterized in that the positioning device of the
lithographic device is a positioning device according to the
invention, wherein each of the object holders of the positioning
device is a substrate holder of the lithographic device, and
wherein the first position of the object holders is a
characterization position which is present near the
characterization unit. As a result of the use of the positioning
device according to the invention in the lithographic device
according to the invention, a characterization process involving a
first series of positioning steps of the first substrate holder can
be carried out in the first position by means of the first
displacement unit of the positioning device, and an exposure
process involving a second series of positioning steps of the
second substrate holder can be carried out in the second position
by means of the second displacement unit of the positioning device
simultaneously with and independently from the first process. The
first process can also be carried out with the second substrate
holder in the first position and, simultaneously and independently,
the second process can be carried out with the first object holder
in the second position.
A particular embodiment of a positioning device according to the
invention is characterized in that the displacement units each
comprise an X-motor having a first part extending parallel to the
X-direction and a second part which is displaceable along the first
part of the X-motor and can be coupled alternately to the first
object holder and to the second object holder, and two Y-motors
each having a first part extending parallel to the Y-direction and
a second part which is displaceable along the first part of the
relevant Y-motor, the first part of the X-motor of each
displacement unit being connected to the second parts of the two
Y-motors of the relevant displacement unit. Since the first part of
the X-motor of each displacement unit is connected to the second
parts of the two Y-motors of the relevant displacement unit, a
comparatively stiff and stable support of the X-motor by the two
Y-motors is obtained, which benefits the positioning accuracy of
the displacement unit. Since the first displacement unit has a
limited displacing range from the first position to the
intermediate position and the second displacement unit has a
limited displacing range from the intermediate position to the
second position, the four Y-motors of the two displacement units
can be arranged in two lines, which leads to a compact and simple
construction of the positioning device.
A further embodiment of a positioning device according to the
invention is characterized in that the first parts of the Y-motors
of the two displacement units are connected to a common balancing
unit which is guided relative to a base of the positioning device
so as to be displaceable parallel to the X-direction and parallel
to the Y-direction and to be rotatable about an axis of rotation
extending perpendicularly to the X-direction and the Y-direction.
Since the first parts of the Y-motors of the displacement units are
connected to said common balancing unit, reaction forces of the
X-motors and the Y-motors of the displacement units are transmitted
via the first parts of the Y-motors to the balancing unit and are
converted into displacements of the balancing unit parallel to the
X-direction and parallel to the Y-direction and rotations of the
balancing unit about said axis of rotation relative to the base. In
this manner, a transmission of the reaction forces to the base, the
guiding surface, and the object holders is prevented as much as
possible, so that the positioning accuracy of the positioning
device is further improved.
A yet further embodiment of a positioning device according to the
invention is characterized in that the object holders each comprise
a basic part which is guided over the guiding surface and can be
coupled to the displacement units, and an object table which is
displaceable relative to the basic part by means of an actuator
unit of the relevant object holder. In this yet further embodiment
of the positioning device, the object tables of the object holders
are displaceable by the displacement units over comparatively large
distances and with comparatively low accuracies, while the object
tables are displaceable by said actuator units over comparatively
small distances and with comparatively high accuracies. In this
manner, the displacement units can be of a relatively simple,
conventional type, while the dimensions of the accurate actuator
units can be limited as much as possible.
A particular embodiment of a positioning device according to the
invention is characterized in that the object table of each of the
object holders is displaceable relative to the basic part parallel
to the X-direction, parallel to the Y-direction, and parallel to a
Z-direction extending perpendicularly to the X-direction and the
Y-direction, and is pivotable relative to the basic part about a
first pivot axis extending parallel to the X-direction, a second
pivot axis extending parallel to the Y-direction, and a third pivot
axis extending parallel to the Z-direction. In this manner, a high
degree of adjustability of the object tables relative to the basic
parts is obtained.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be explained in more detail below with reference
to the drawing, in which
FIG. 1 diagrammatically shows a lithographic device according to
the invention,
FIG. 2 is a diagrammatic plan view of a first embodiment of a
positioning device according to the invention suitable for use in
the lithographic device of FIG. 1,
FIG. 3 shows the positioning device of FIG. 2, two substrate
holders of the positioning device being in an intermediate
position, and
FIG. 4 is a diagrammatic plan view of a second embodiment of a
positioning device according to the invention suitable for use in
the lithographic device of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The lithographic device according to the invention shown
diagrammatically in FIG. 1 is used for the exposure of
semiconductor substrates in the manufacturing process of integrated
semiconductor circuits and comprises a frame 1 which supports in
that order, as seen parallel to a vertical Z-direction, a
positioning device 3 according to the invention, a focusing unit 5,
a mask holder 7, and a radiation source 9. The lithographic device
is an optical lithographic device whose radiation source 9
comprises a light source 11. The mask holder 7 comprises a support
surface 13 which extends perpendicularly to the Z-direction and on
which a mask 15 can be placed comprising a pattern or a sub-pattern
of an integrated semiconductor circuit. The focusing unit 5 is an
imaging or projection system and comprises an optical lens system
17 having a main optical axis 19 extending parallel to the
Z-direction and an optical reduction factor of, for example, 4 or
5. The positioning device 3 comprises a first substrate holder 21
and a second substrate holder 23 which is identical to the first
substrate holder 21. The substrate holders 21, 23 each comprise a
support surface 25, 27 which extends perpendicularly to the
Z-direction. In the situation shown in FIG. 1, a first
semiconductor substrate 29 is present on the support surface 25 of
the first substrate holder 21 and a second semiconductor substrate
31 is present on the support surface 27 of the second substrate
holder 23. The positioning device 3 further comprises a guiding
surface 33 extending parallel to a horizontal X-direction which is
perpendicular to the Z-direction and parallel to a horizontal
Y-direction which is perpendicular to the X-direction and the
Z-direction. The substrate holders 21, 23 are each guided over the
guiding surface 33 and are each displaceable over the guiding
surface 33 parallel to the X-direction and parallel to the
Y-direction by means of a displacement system 35 of the positioning
device 3.
In the situation shown in FIG. 1, the first substrate holder 21
with the first semiconductor substrate 29 is in a second position
of the positioning device 3 which corresponds to an exposure
position of the lithographic device which is present near the
focusing unit 5. In this position, a light beam originating from
the light source 11 is guided through the mask 15 and is focused on
the first semiconductor substrate 29 by means of the focusing unit
5, so that the pattern present on the mask 15 is imaged on a
reduced scale on the first semiconductor substrate 29. The first
semiconductor substrate 29 comprises a large number of individual
fields on which identical semiconductor circuits are to be imaged.
The fields of the first semiconductor substrate 29 are
consecutively exposed through the mask 15 for this purpose. The
exposure process used in the lithographic device of FIG. 1 is a so
called step-and-repeat exposure process according to which the
first semiconductor substrate 29 and the mask 15 are in fixed
positions relative to the focusing unit 5 during the exposure of an
individual field of the first semiconductor substrate 29, and
according to which a next field of the first semiconductor
substrate 29 is brought into position relative to the focusing unit
5 after the exposure of a previously exposed field in that the
first substrate holder 21 is displaced parallel to the X-direction
and/or parallel to the Y-direction by the displacement system 35 of
the positioning device 3. This process is repeated a number of
times, with a different mask each time, so that complicated
integrated semiconductor circuits with a layered structure can be
manufactured.
In the situation shown in FIG. 1, the second substrate holder 23
with the second semiconductor substrate 31 is in a first position
of the positioning device 3 which corresponds to a characterization
position of the lithographic device. In the situation shown, a
previous semiconductor substrate, which was fully exposed in the
exposure position via the mask 15, was unloaded from the second
substrate holder 23 and was transported to a stack of semiconductor
substrates under manufacture not shown in the figure. The second
semiconductor substrate 31 shown in FIG. 1 is a next semiconductor
substrate which has just been taken from said stack of
semiconductor substrates and loaded on the second substrate holder
23 and which has to be exposed via the mask 15 after the first
semiconductor substrate 29. In the characterization position, the
second semiconductor substrate 31 is characterized by a
characterization unit 37 of the lithographic device which is also
supported by the frame 1. When the second semiconductor substrate
31 has been fully characterized and the first semiconductor
substrate 29 has been fully exposed, the second substrate holder 23
with the second semiconductor substrate 31 is displaced by the
displacement system 35 from the characterization position into the
exposure position and the first substrate holder 21 with the first
semiconductor substrate 29 is displaced by the displacement system
35 from the exposure position into the characterization position.
The characterization unit 37 comprises, for example, a measuring
system which is used for measuring the positions of the individual
fields of the second semiconductor substrate 31 relative to the
second substrate holder 23. Since these positions are already
measured in the characterization position, the individual fields of
the second semiconductor substrate 31 can subsequently be
positioned relative to the focusing unit 5 in the exposure position
by measuring the position of the second substrate holder 23
relative to the focusing unit 5. In this manner, the time required
to position the individual fields of the successive semiconductor
substrates relative to the focusing unit 5 in the exposure position
is limited considerably, so that the throughput of the lithographic
device is considerably improved. Since the position of each
individual field of the second semiconductor substrate 31 has to be
measured in the characterization position, a step wise displacement
of the second substrate holder 23 with the second semiconductor
substrate 31 is carried out by the displacement system 35 of the
positioning device 3 in the characterization position. As a result
of the use of the two separate identical substrate holders 21 and
23, the exposure process of a semiconductor substrate in the
exposure position can be carried out simultaneously with the unload
process of a previous semiconductor substrate and the load and
characterization processes of a next semiconductor substrate in the
characterization position, so that the throughput of the
lithographic device is further improved.
As shown in FIG. 2, the displacement system 35 of the positioning
device 3 comprises a first displacement unit 39 and a second
displacement unit 41. The substrate holders 21, 23 each comprise an
aerostatically supported foot 43, 45 provided with a static gas
bearing by means of which the relevant substrate holder 21, 23 is
guided over the guiding surface 33. The guiding surface 33
constitutes an upper surface of a granite block 47 which is
fastened to the frame 1 of the lithographic device. Furthermore,
the substrate holders 21, 23 each comprise a first coupling member
49, 51 and a second coupling member 53, 55 by means of which the
substrate holders 21, 23 can be coupled alternately to a coupling
member 57 of the first displacement unit 39 and to a coupling
member 59 of the second displacement unit 41, respectively. In the
situation shown in FIG. 2, the first substrate holder 21 is coupled
to the coupling member 59 of the second displacement unit 41 and
the second substrate holder 23 is coupled to the coupling member 57
of the first displacement unit 39. Alternatively, the first
substrate holder 21 can be coupled to the coupling member 57 of the
first displacement unit 39 and the second substrate holder 23 can
be coupled to the coupling member 59 of the second displacement
unit 41. The coupling members 49, 51, 53, 55, 57, 59 may be of a
type which is known and usual per se, such as, for example, a
mechanical or an electromechanical coupling member.
As FIG. 2 shows, the first displacement unit 39 and the second
displacement unit 41 each comprise a linear X-motor 61, 63 and two
linear Y-motors 65, 67, 69, 71 of a conventional type which is
known and usual per se. The X-motors 61, 63 each comprise a first
part 73, 75 extending parallel to the X-direction and a second part
77, 79 which is displaceable along the first part 73, 75 of the
relevant X-motor 61, 63 and comprises the coupling member 57, 59 of
the relevant X-motor 61, 63. The Y-motors 65, 67, 69, 71 each
comprise a first part 81, 83, 85, 87 extending parallel to the
Y-direction and a second part 89, 91, 93, 95 which is displaceable
along the first part 81, 83, 85, 87 of the relevant Y-motor 65, 67,
69, 71. The X-motor 61 and the two Y-motors 65, 67 of the first
displacement unit 39 are mutually arranged in a H-configuration, a
first end 97 and a second end 99 of the first part 73 of the
X-motor 61 being coupled to the second part 89 of the Y-motor 65
and to the second part 91 of the Y-motor 67, respectively.
Likewise, the X-motor 63 and the two Y-motors 69, 71 of the second
displacement unit 41 are mutually arranged in a H-configuration, a
first end 101 and a second end 103 of the first part 75 of the
X-motor 63 being coupled to the second part 93 of the Y-motor 69
and to the second part 95 of the Y-motor 71, respectively.
In the situation shown in FIG. 2, the second substrate holder 23 is
in the first position or characterization position and a
characterization process involving a first series of positioning
steps of the second substrate holder 23 is carried out by means of
the first displacement unit 39. Simultaneously, the first substrate
holder 21 is in the second position or exposure position and an
exposure process involving a second series of positioning steps of
the first substrate holder 21 is carried out by means of the second
displacement unit 41. Thus, as a result of the use of the first
displacement unit 39 and the second displacement unit 41, the
characterization process can be carried out not only simultaneously
with but also independently from the exposure process. When the
exposure process with the first substrate holder 21 and the
characterization process with the second substrate holder 23 have
been completed, the first substrate holder 21 is displaced by means
of the second displacement unit 41 from the exposure position into
an intermediate position M' between the exposure position and the
characterization position as shown in FIG. 3, and the second
substrate holder 23 is displaced by means of the first displacement
unit 39 from the characterization position into an intermediate
position M'' between the exposure position and the characterization
position. In said intermediate positions M' and M'', the second
coupling member 53 of the first substrate holder 21 is uncoupled
from the coupling member 59 of the second displacement unit 41 and
the first coupling member 51 of the second substrate holder 23 is
uncoupled from the coupling member 57 of the first displacement
unit 39. Subsequently, the coupling member 57 of the first
displacement unit 39 is coupled to the first coupling member 49 of
the first substrate holder 21 and the coupling member 59 of the
second displacement unit 41 is coupled to the second coupling
member 55 of the second substrate holder 23, as shown in FIG. 3.
Then, the first substrate holder 21 is displaced by the first
displacement unit 39 from the intermediate position M' into the
characterization position where the substrate present on the first
substrate holder 21 is unloaded and a next substrate is loaded and
characterized. Simultaneously therewith and independently
therefrom, the second substrate holder 23 is displaced by the
second displacement unit 41 from the intermediate position M'' into
the exposure position where the substrate present on the second
substrate holder 23 is exposed. Since the first displacement unit
39 is suitable for displacing both substrate holders 21 and 23 from
the first position or characterization position into the
intermediate positions M' and M'' and the second displacement unit
41 is suitable for displacing both substrate holders 21 and 23 from
the intermediate positions M' and M'' into the exposure position, a
distance over which each displacement unit 39, 41 must be able to
displace the substrate holders 21 and 23 is reduced, so that the
required dimensions of the displacement units 39, 41 are reduced.
As FIG. 2 shows, particularly the dimensions of the Y-motors 65,
67, 69, 71 of the displacement units 39, 41 are considerably
reduced as seen parallel to the Y-direction. Furthermore, the use
of the two displacement units 39, 41 prevents that the displaceable
parts of the displacement system 35, in particular the X-motors 61
and 63, must be constructed so as to be capable of passing one
another, as a result of which a comparatively simple construction
of the displacement system 35 is achieved. The arrangement of the
two X-motors 61, 63 and the four Y-motors 65, 67, 69, 71 in two
H-configurations leads to a comparatively stiff and stable support
of X-motors 61, 63 by the relevant Y-motors 65, 67, 69, 71, which
benefits the positioning accuracy of the displacement units 39, 41.
The limited displacing range of the displacement units 39, 41 as
seen parallel to the Y-direction enables the mutual arrangement of
the four Y-motors 65, 67, 69, 71 in two lines of two Y-motors 65,
69 and 67, 71 each, which leads to a compact and simple
construction of the positioning device 3.
FIG. 4 shows a second embodiment of a positioning device 105
according to the invention suitable for use in the lithographic
device according to the invention. Corresponding parts of the first
embodiment of the positioning device 3 and the second embodiment of
the positioning device 105 are indicated by means of corresponding
reference numerals in FIGS. 2, 3, and 4. Hereafter, only the main
differences between the positioning devices 3 and 105 will be
discussed.
The substrate holders 21 and 23 of the positioning device 105 each
comprise a basic part 107, 109 which comprises the aerostatically
supported foot 43, 45, the first coupling member 49, 51, and the
second coupling member 53, 55 of the relevant substrate holder 21,
23. Furthermore, the substrate holders 21, 23 of the positioning
device 105 each comprise a substrate table 111, 113 which comprises
the support surface 25, 27 of the relevant substrate holder 21, 23.
The substrate holders 21, 23 each comprise ah actuator unit 115,
117 which is indicated diagrammatically only in FIG. 4 and by means
of which the substrate table 111, 113 of the relevant substrate
holder 21, 23 is displaceable relative to the basic part 107, 109
of the relevant substrate holder 21, 23. In the second embodiment
of the positioning device 105 according to the invention, the
actuator units 115, 117 each comprise a system of contactless
Lorentz-force motors which are known and usual per se and by means
of which the substrate table 111, 113 of the relevant substrate
holder 21, 23 is displaceable relative to the basic part 107, 109
of the relevant substrate holder 21, 23 with comparatively high
accuracies and over comparatively small distances in directions
parallel to the X-direction, parallel to the Y-direction, and
parallel to the Z-direction, and by means of which the substrate
table 111, 113 of the relevant substrate holder 21, 23 is pivotable
relative to the basic part 107, 109 of the relevant substrate
holder 21, 23 with comparatively high accuracies and over
comparatively small angles about a first pivot axis extending
parallel to the X-direction, a second pivot axis extending parallel
to the Y-direction, and a third pivot axis extending parallel to
the Z-direction. In this manner, the displacement units 39, 41 each
constitute a so called coarse-fine displacement unit wherein the
substrate holders 21, 23 with the substrate tables 111, 113 are
displaceable over comparatively large distances and with
comparatively low accuracies by means of the X-motors 61, 63 and
the Y-motors 65, 67, 69, 71 of the displacement units 39, 41, and
wherein the substrate tables 111, 113 are displaceable and
pivotable with comparatively high accuracies and over comparatively
low distances and small angles relative to the basic parts 107, 109
of the substrate holders 21, 23 by means of the actuator units 115,
117 of the displacement units 39, 41. In this manner, the X-motors
61, 63 and the Y-motors 65, 67, 69, 71 can be of a relatively
simple, conventional, and low-cost type, while the required
dimensions and therefore the costs of the accurate and advanced
actuator units 115, 117 can be limited as much as possible. The use
of the actuator units 115, 117 as described further provides a high
degree of adjustability of the substrate tables 111, 113 relative
to the focusing unit 5 and relative to the characterization unit 37
of the lithographic device.
As FIG. 4 further shows, the first parts 81, 83, 85, 87 of the
Y-motors 65, 67, 69, 71 of the displacement units 39, 41 of the
positioning device 105 are fastened to a balancing unit 119 which
is common for the two displacement units 39, 41. The balancing unit
119 comprises a first beam 121 which extends substantially parallel
to the Y-direction and to which the first part 81 of the Y-motor 65
of the first displacement unit 39 and the first part 85 of the
Y-motor 69 of the second displacement unit 41 are fastened, and a
second beam 123 which also extends substantially parallel to the
Y-direction and to which the first part 83 of the Y-motor 67 of the
first displacement unit 39 and the first part 87 of the Y-motor 71
of the second displacement unit 41 are fastened. The first beam 121
and the second beam 123 are interconnected by means of a first
cross-beam 125 and a second cross-beam 127, the beams 121 and 123
and the cross-beams 125 and 127 being arranged in a rectangular
configuration which surrounds the granite block 47 carrying the
guiding surface 33. As FIG. 4 diagrammatically shows, the first
beam 121 of the balancing unit 119 is guided by means of static gas
bearings 129 over a further guiding surface 131 which is provided
on a base 133 of the positioning device 105 and extends parallel to
the X-direction and parallel to the Y-direction, and the second
beam 123 of the balancing unit 119 is guided by means of static gas
bearings 135 over said further guiding surface 131. Thus, the
balancing unit 119 is displaceable in direction parallel to the
X-direction and parallel to the Y-direction and is rotatable about
an axis of rotation extending parallel to the Z-direction. In
operation, reaction forces of the actuator units 115, 117 of the
displacement units 39, 41 directed parallel to the X-direction
and/or parallel to the Y-direction are transmitted via the X-motors
61, 63 and the Y-motors 65, 67, 69, 71 to the balancing unit 119,
reaction forces of the X-motors 61, 63 of the displacement units
39, 41 directed parallel to the X-direction and/or parallel to the
Y-direction are transmitted via the Y-motors 65, 67, 69, 71 to the
balancing unit 119, and reaction forces of the Y-motors 65, 67, 69,
71 of the displacement units 39, 41 directed parallel to the
X-direction and/or parallel to the Y-direction are directly
transmitted to the balancing unit 119. Since the balancing unit 119
is guided over the further guiding surface 131 by means of the
static gas bearings 129, 135, said reaction forces are
substantially completely converted into relatively small
displacements of the balancing unit 119 in directions parallel to
the X-direction and/or parallel to the Y-direction and into
relatively small rotations of the balancing unit 119 about said
axis of rotation extending parallel to the Z-direction. In this
manner, mechanical vibrations, which may be caused by said reaction
forces in the base 133 and which may be transmitted to the granite
block 47 and the substrate holders 21, 23 of the lithographic
device 105 and to the frame 1 of the lithographic device, are
prevented as much as possible, so that the positioning accuracy of
the displacement system 35 of the positioning device 105 is further
improved.
It is noted that another type of displacement unit may be used in
the positioning device according to the invention instead of the
displacement units 39, 41 used in the positioning devices 3, 105
described before. For example, the displacement units of the
positioning device may each alternatively comprise a single linear
X-motor and a single linear Y-motor for large-distance
displacements of the relevant object holder and an actuator unit
solely comprising an X-Lorentz-force motor and a Y-Lorentz-force
motor for small-distance displacements of the relevant object
table.
It is further noted that the invention also relates to lithographic
devices in which an exposure process following the step-and-scan
principle is applied. Such a lithographic device is provided with a
further positioning device by means of which the mask holder is
displaceable in a scan direction which is parallel to, for example,
the X-direction. According to the stepand-scan process, the mask
and the semiconductor substrate are not in fixed positions relative
to the focusing unit during the exposure process but are displaced
simultaneously in the scan direction, so that the pattern present
on the mask is scanned.
It is finally noted, that a positioning device according to the
invention may be used not only in a lithographic device but also in
other devices where two object tables have to perform a series of
positioning steps simultaneously and independently from each other.
Examples are finishing machines, machine tools, and other machines
or devices in which an object to be machined or processed is first
characterized relative to an object holder in a characterization
position and is subsequently machined or processed in an
operational position.
* * * * *