U.S. patent application number 11/613556 was filed with the patent office on 2007-04-19 for dual substrate loadlock process equipment.
Invention is credited to Wendell T. Blonigan, Akihiro Hosokawa, Shinichi Kurita.
Application Number | 20070086881 11/613556 |
Document ID | / |
Family ID | 23843644 |
Filed Date | 2007-04-19 |
United States Patent
Application |
20070086881 |
Kind Code |
A1 |
Kurita; Shinichi ; et
al. |
April 19, 2007 |
DUAL SUBSTRATE LOADLOCK PROCESS EQUIPMENT
Abstract
One embodiment relates to a loadlock having a first support
structure therein to support one unprocessed substrate and a second
support structure therein to support one processed substrate. The
first support structure is located above the second support
structure. The loadlock includes an elevator to control the
vertical position of the support structures. The loadlock also
includes a first aperture to permit insertion of an unprocessed
substrate into the loadlock and removal of a processed substrate
from the loadlock, as well as a second aperture to permit removal
of an unprocessed substrate from the loadlock and insertion of a
processed substrate into the loadlock. A cooling plate is also
located in the loadlock. The cooling plate includes a surface
adapted to support a processed substrate thereon. A heating device
may be located in the loadlock above the first support
structure.
Inventors: |
Kurita; Shinichi; (San Jose,
CA) ; Blonigan; Wendell T.; (Union City, CA) ;
Hosokawa; Akihiro; (Cupertino, CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Family ID: |
23843644 |
Appl. No.: |
11/613556 |
Filed: |
December 20, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10842079 |
May 10, 2004 |
|
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11613556 |
Dec 20, 2006 |
|
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09464362 |
Dec 15, 1999 |
6949143 |
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10842079 |
May 10, 2004 |
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Current U.S.
Class: |
414/805 ;
118/719; 156/345.32; 414/217; 414/939 |
Current CPC
Class: |
C23C 14/566 20130101;
H01L 21/67748 20130101; C23C 16/54 20130101; B65G 49/068 20130101;
B65G 2249/04 20130101; H01L 21/67201 20130101; C23C 14/568
20130101; H01L 21/67109 20130101; H01L 21/67103 20130101; H01L
21/67167 20130101; H01L 21/68742 20130101; B65G 2249/02 20130101;
H01L 21/67739 20130101; H01L 21/67745 20130101 |
Class at
Publication: |
414/805 ;
118/719; 156/345.32; 414/217; 414/939 |
International
Class: |
H01L 21/677 20060101
H01L021/677; H01L 21/306 20060101 H01L021/306; C23C 16/00 20060101
C23C016/00; B65H 1/00 20060101 B65H001/00 |
Claims
1. A loadlock chamber comprising: a chamber body having a first and
second substrate access port; a first plurality of support pins
disposed in the chamber body and arranged to support a first
substrate thereon; a second plurality of support pins disposed in a
chamber body and arranged to support a second substrate thereon;
and a cooling plate disposed in the chamber body below the first
plurality of support pins, wherein a distance between substrate
supporting ends of the second plurality of support pins and the
cooling plate are adjustable.
2. The load lock chamber of claim 1, wherein cooling plate further
comprises: a plurality of holes through with the second plurality
of support pins are disposed.
3. The loadlock of claim 1, wherein the first plurality of support
pins are moveable relative to the cooling plate.
4. The loadlock of claim 1, wherein the cooling plate is positioned
to accept a processed substrate from the second plurality of
support pins.
5. The loadlock of claim 1, wherein the cooling plate includes at
least one groove on its surface for receiving a portion of a
robotic end effector.
6. The loadlock of claim 1, wherein the cooling plate further
includes at least one coolant carrying channel.
7. The loadlock of claim 1, further comprising an elevator to
control the vertical position of the first and second plurality of
support pins.
8. The loadlock of claim 1, further comprising a heating device
disposed above the upper structure.
9. The loadlock of claim 1 further comprising: a lift plate located
below the cooling plate and moveable to actuate the second
plurality of support pins.
10. A loadlock comprising: a chamber body; a first plurality of
support pins in the chamber body and arranged to support a first
substrate; a second plurality of support pins disposed in the
chamber body above the first plurality of support pins, the second
first plurality of support pins moveable to a first position
selected to support a first substrate; an elevator for controlling
a vertical position of the second plurality of support pins; a
cooling plate including a surface adapted to support the first
substrate thereon when the second plurality of support pins are in
a second position; and a heating device located above the first
plurality of support pins.
11. The loadlock of claim 10, wherein the second plurality of
support pins extends through the cooling plate when in the first
position.
12. The loadlock of claim 10, wherein the cooling plate is attached
to the chamber body.
13. The loadlock of claim 10 further comprising: a middle plate
between the first and second plurality of support pins.
14. A method for processing substrates comprising: delivering an
unprocessed substrate to first substrate slot defined in a loadlock
chamber; pumping down the load lock chamber while the unprocessed
substrate is in the first substrate slot; delivering the
unprocessed substrate to a chamber outside of the loadlock chamber;
delivering a processed substrate from the chamber outside of the
loadlock to a second substrate slot defined in the loadlock
chamber, the second substrate slot having a height; and reducing
the height of the second substrate slot while the processed
substrate is in the second substrate slot; and cooling the
processed substrate while the processed substrate is in the reduced
height second substrate slot.
15. A method for processing substrates comprising: delivering an
unprocessed substrate to an upper support structure in a loadlock
chamber through a first opening in the loadlock; closing the first
opening and evacuating the loadlock chamber; delivering the
unprocessed substrate to a chamber outside of the loadlock chamber
through a second opening in the loadlock; delivering a processed
substrate from the chamber outside of the loadlock chamber to the
lower support structure through the second opening in the loadlock
chamber; and delivering the processed substrate to a cooling plate
in the loadlock chamber.
16. The method of claim 16, wherein delivering the processed
substrate to the cooling plate comprises: lowering the lower
support structure relative to the cooling plate.
17. The method of claim 16, further comprising: cooling the
substrate on the cooling plate; raising the lower support structure
relative to the cooling plate to remove the processed substrate
from the cooling plate; and removing the processed substrate from
the loadlock through the first opening.
18. The method of claim 16, further comprising: heating the
processed substrate in the loadlock prior to venting the loadlock
chamber.
19. The method of claim 16, further comprising: lowering the lower
support structure relative to the first opening after removing the
processed substrate from the loadlock chamber through the first
opening; and aligning the upper support structure to accept an
unprocessed substrate on upper support structure through the first
opening.
20. The method of claim 16, wherein the upper and lower support
structure move together relative the cooling place.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 10/842,079, filed May 10, 2004, which is a
continuation of U.S. Pat. No. 6,949,143, issued Sep. 27, 2005,
which are herein incorporated by reference in their entireties.
Priority from these applications is claimed.
FIELD OF THE INVENTION
[0002] The present invention relates to substrate processing
systems, and, more particularly, to loadlock systems for handling
substrates.
BACKGROUND OF THE INVENTION
[0003] Substrates such as, for example, glass panels used in
applications such as television and computer displays may be
fabricated using sequential steps including physical vapor
deposition (PVD), chemical vapor deposition (CVD), etching, and
annealing to produce the desired device. These steps may be carried
out using a variety of processing systems having multiple chambers.
One such system is known as a "cluster tool". A cluster tool
generally includes a central wafer handling module or transfer
chamber and a number of peripheral chambers including a loadlock
chamber through which workpieces are introduced into and removed
from the system and a plurality of other chambers for carrying out
processing steps such as heating, etching, and deposition. The
cluster tool also generally includes a robot for transferring
workpieces between the chambers.
[0004] The processing of large glass substrates used for displays
is in some ways similar to the processing of other types of
substrates such as semiconductor wafers. Such glass substrates,
however, are often larger than typical silicon wafers. For example,
glass substrates may have dimensions of 550 mm by 650 mm, with
trends towards even larger sizes such as 650 mm by 830 mm and
larger, to permit the formation of larger displays. The use of
large glass substrates introduces complexities into processing that
may not be present when processing other types of substrates. For
example, in addition to their size, glass substrates used for
displays are typically rectangular in shape. The large size and
shape of glass substrates can make them difficult to transfer from
position to position within a processing system when compared with
smaller, circular-shaped substrates. As a result, systems for
processing glass substrates generally require larger chambers,
apertures, and transfer mechanisms. In addition, it is known to
utilize large cassettes holding approximately 12 substrates within
the loadlock in order to supply a large number of substrates to the
processing chambers for batch processing operations. The need for
larger chamber sizes to handle large substrates, as well as the use
of large substrate cassettes in the loadlock, also leads to a
requirement for larger and more powerful vacuum pumps, power
supplies, control mechanisms and the like and a corresponding
increase in system cost.
[0005] In addition, glass substrates often have different thermal
properties than silicon substrates. In particular, glass generally
has a relatively low thermal conductivity, which can make it more
difficult to uniformly heat and cool the substrate. Temperature
gradients may occur across the glass substrate, which can lead to
undesirable stresses in the substrate upon cooling. The heat loss
near the substrate edges tends to be greater than near the center.
Temperature gradients during processing can also result in the
components formed on the substrate surface having non-uniform
electrical (and structural) characteristics. As a result, to
maintain adequate temperature control, heating and cooling
operations are often performed relatively slowly. As the system
components become larger in size, these steps may be slowed even
more due to the longer time it generally takes to heat and cool
large components in a large volume chamber. These slow operations
tend to lower the system throughput.
SUMMARY OF THE PREFERRED EMBODIMENTS
[0006] Certain embodiments of the present invention relate to
loadlock devices for use in substrate processing systems that are
relatively compact in size and that can achieve substrate transfer,
cooling and/or heating operations in an efficient manner.
[0007] One embodiment relates to a loadlock having a first support
structure adapted to support a first substrate and a cooling plate
adapted to support a second substrate.
[0008] Another embodiment relates to a loadlock having a first
support structure to support one unprocessed substrate and a second
support structure to support one processed substrate. The first
support structure is located above the second support structure and
an elevator is provided to control the vertical position of the
support structures. The loadlock also includes a first aperture to
permit insertion of an unprocessed substrate into the loadlock and
removal of a processed substrate from the loadlock, as well as a
second aperture to permit removal of an unprocessed substrate from
the loadlock and insertion of a processed substrate into the
loadlock. A cooling plate having a surface adapted to support a
processed substrate is also included in the loadlock. The cooling
plate may be designed to have multiple zones for preferentially
controlling the cooling rate of a processed substrate thereon. A
heating device is also provided in the loadlock above the first
support structure. The heating device may be used to heat an
unprocessed substrate on the first support structure prior to
inserting the unprocessed substrate into another chamber for
subsequent processing.
[0009] Another embodiment relates to a semiconductor processing
system having at least one processing chamber, a transfer chamber
connected to the processing chamber, and a loadlock connected to
the transfer chamber. The loadlock includes a single substrate
upper support structure and a single substrate lower support
structure, as well as a transfer aperture to transfer a single
substrate between the transfer chamber and the loadlock. The
loadlock also includes an elevator for raising and lowering the
supports and a cooling plate positioned to accept a single
substrate from the single substrate lower support structure.
[0010] Another embodiment relates to a loadlock including a
loadlock chamber and a support structure in the chamber. The
support structure is adapted to accept a single substrate from a
robot arm. A cooling plate is also located in the chamber and is
positioned to accept a single substrate from the support structure.
The support structure is movable relative to the cooling plate.
[0011] Another embodiment relates to a loadlock system having a
first means for supporting only a single unprocessed substrate and
a second means for supporting only a single processed substrate.
The first means is located above the second means. The system also
includes a delivery means for delivering a processed substrate to a
cooling plate located in the loadlock system.
[0012] Embodiments of the present invention also relate to methods
including utilizing a loadlock and methods for processing
substrates. One such embodiment relates to a method for using a
loadlock including delivering an unprocessed substrate to an upper
support structure in the loadlock through an opening in the
loadlock. The opening is closed and the loadlock evacuated to the
desired pressure level. The unprocessed substrate is transferred to
a chamber outside of the loadlock. A processed substrate is
delivered from a chamber outside of the loadlock (such as, for
example, a transfer chamber or other chamber in a processing
system) to a lower support structure in the loadlock. The processed
substrate is delivered from said lower support structure to a
cooling plate in the loadlock, and the processed substrate is
cooled.
[0013] Another embodiment relates to a method for processing
substrates including delivering an unprocessed substrate to an
upper support structure in a loadlock through a first opening in
the loadlock. The opening is closed and the loadlock evacuated. The
unprocessed substrate is delivered to a chamber outside of the
loadlock through a second opening in the loadlock. A processed
substrate is delivered from a chamber outside of the loadlock to
the lower support structure through the second opening in the
loadlock. The second support structure is lowered to deliver the
processed substrate to a cooling plate in the loadlock.
[0014] Still another embodiment relates to a method for processing
a substrate including delivering one unprocessed substrate from an
unprocessed substrate supply located outside of a loadlock to a
first loadlock support structure inside of the loadlock, using a
first robot. The unprocessed substrate is transferred from the
first loadlock support structure to a transfer chamber using a
second robot. The unprocessed substrate is transferred from the
transfer chamber to at least one processing chamber to process the
unprocessed substrate to form a processed substrate. The processed
substrate is transferred from the at least one processing chamber
to the transfer chamber. The processed substrate is transferred
from the transfer chamber to a second loadlock support structure
using the second robot. The second loadlock support structure may
be located below the first loadlock support structure. The
processed substrate is transferred from the second loadlock support
structure to a cooling plate in the loadlock and cooled. The
processed substrate is removed from the loadlock using the first
robot.
[0015] Yet another embodiment relates to another method for
processing substrates including delivering a single unprocessed
substrate to an upper support structure in a loadlock and
evacuating the loadlock. The single unprocessed substrate is
delivered from the loadlock to the transfer chamber. A single
processed substrate is delivered from a transfer chamber to a lower
support structure in said loadlock. The single processed substrate
is delivered from said lower support structure to a cooling plate
in said loadlock. The loadlock is vented and the single processed
substrate is delivered to a location external to the loadlock and
the transfer chamber. Another single unprocessed substrate is
delivered to the loadlock.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Embodiments of the invention are described with reference to
the accompanying drawings which, for illustrative purposes, are
schematic and not drawn to scale.
[0017] FIG. 1 is a top schematic view of a cluster tool including a
loadlock, transfer chamber, and processing chambers according to an
embodiment of the present invention.
[0018] FIG. 2 is a cross-sectional view of a portion of the
loadlock of FIG. 1 in accordance with an embodiment of the present
invention.
[0019] FIG. 3 is a perspective view of a loadlock according to an
embodiment of the present invention.
[0020] FIG. 4 is a perspective view of the loadlock of FIG. 3
including an outer body section around an interior compartment
according to an embodiment of the present invention.
[0021] FIG. 5 is a perspective view of the loadlock of FIGS. 3 and
4 including a cover portion and a lower portion according to an
embodiment of the present invention.
[0022] FIG. 6a is an exploded view of certain interior components
of a loadlock according to an embodiment of the present
invention.
[0023] FIG. 6b is a perspective view of some of the loadlock
components of FIG. 6 when assembled together according to an
embodiment of the present invention.
[0024] FIGS. 7a-f illustrate a processing scheme in accordance with
an embodiment of the present invention.
[0025] FIG. 8 is a perspective view of a portion of a loadlock
system in a load/unload condition in accordance with an embodiment
of the present invention.
[0026] FIG. 9 is a perspective view of a portion of a loadlock
system in a cool down condition in accordance with an embodiment of
the present invention.
[0027] FIG. 10 is a cross-sectional view of a cooling plate with a
coolant carrying channel therein in accordance with an embodiment
of the present invention.
[0028] FIG. 11 is a cross-sectional view of a cooling plate with a
coolant-carrying channel at a bottom portion of the cooling plate
in accordance with an embodiment of the present invention.
[0029] FIG. 12 is a cross-sectional view of a middle plate with a
coolant carrying channel therein in accordance with an embodiment
of the present invention.
[0030] FIG. 13 is a cross-sectional view of a middle plate with a
coolant carrying channel at an upper portion of the middle plate in
accordance with an embodiment of the present invention.
[0031] FIG. 14 is a top view of a plate having a high emissivity
area in accordance with an embodiment of the present invention.
[0032] FIG. 15 is a cross-sectional view of a cooling plate and
substrate support system according to an embodiment of the present
invention.
[0033] FIG. 16 is a top cross-sectional view of a cluster chamber
according to an embodiment of the present invention.
[0034] FIG. 17 is a top cross-sectional view of a cluster chamber
according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0035] Certain preferred embodiments relate to loadlock systems and
methods of operation. These loadlock systems may be used as part of
a larger cluster type processing system. As illustrated in FIG. 1,
one embodiment includes a cluster system having a central substrate
handling module or transfer chamber 10, a number of peripheral
process chambers 20, and at least one loadlock mechanism 30 for
inserting substrates into the system and removing substrates from
the system. The central transfer chamber 10 may include a robot 40
therein for picking up and delivering substrates between the
various chambers. The term substrates includes substrates formed
from a variety of materials including, but not limited to glasses,
semiconductors, ceramics, metals, composites, and combinations
thereof.
[0036] A preferred embodiment of the loadlock 30 is illustrated in
the cross-sectional view of FIG. 2. The loadlock 30 preferably
includes a dual substrate cassette 50, with an upper slot 51 for
holding an unprocessed substrate and a lower slot 53 for holding a
processed substrate. The upper slot 51 may preferably be located
between an upper plate 54 and a middle plate 56 of the cassette 50.
The lower slot 53 may preferably be formed between the middle plate
56 and a cooling plate 52, above a lower plate 76 of the cassette
50. The plates 54, 56 and 76 are assembled to form the cassette 50.
The cooling plate 52 is almost entirely located within the cassette
50. However, it is preferably not connected to the cassette 50.
Instead, flange portions 100, 102 of the cooling plate 52 are
preferably attached to a frame member 64 that surrounds the
cassette 50. This structure enables the cassette 50 to move
independently of the cooling plate 52 by coupling the cassette to
an elevator 58 (FIG. 3) through shaft 128. By moving the cassette
50 independently of the cooling plate 52, a substrate on supports
78, 80 within the lower slot 53 can be lowered onto and raised off
of the cooling plate 52 by moving the cassette.
[0037] In certain preferred embodiments, a substrate on the cooling
plate 52 may be cooled by positioning the cooling plate (with the
substrate thereon) and the middle plate 56 very close to one
another. By sandwiching the substrate between the cooling plate 52
and middle plate 56, the substrate can be cooled in an efficient
manner. As will be discussed in more detail later, both the middle
plate 56 and the cooling plate 52 may be water cooled and may have
a high emissivity surface area.
[0038] Progressive views of the loadlock 30 are illustrated in
FIGS. 3-5. The cassette 50 may include an opening 62 for viewing
the cassette interior during operation. FIG. 4 shows the loadlock
30 of FIG. 3, further including the loadlock body portion or frame
member 64 surrounding the cassette 50. A window 66 may be provided
for viewing the interior of the cassette through opening 62, and a
door 68 may be provided for accessing the interior of the loadlock
to insert and remove substrates. The elevator 58 may be positioned
below the cassette 50 and used to move the cassette 50 relative to
the cooling plate 52 and frame member 64. As shown in FIG. 2, the
elevator 58 may include a shaft 128 attached to the bottom of the
cassette 50 through a connection such one or more connectors 130
and plate 132. The connectors 130 may be designed to be adjustable
so that the cassette 50 can be leveled if it becomes misaligned.
Alternatively, the shaft 128 may be directly connected to the
cassette 50.
[0039] FIG. 5 shows the loadlock 30 of FIGS. 3 and 4, further
including a top pressure vessel portion or top cover 70 and a lower
pressure vessel portion or bottom cover 72 to define the loadlock
chamber region. The top cover 70 and bottom cover 72 may be any
suitable structure capable of maintaining appropriate vacuum or
other desired pressure conditions and be capable of surviving
elevated temperatures such as those encountered during substrate
heating. The loadlock 30 may also include a wheeled frame structure
74 for supporting and moving the loadlock 30.
[0040] FIG. 6a illustrates an exploded view of certain components
in the loadlock 30 including components from the cassette 50, the
cooling plate 52 and the frame member 64. FIG. 6b illustrates the
cassette 50 assembled within the frame member 64. The frame member
64 includes openings 96 and 98 on opposite sides, through which
substrates are inserted into and removed from the loadlock. Opening
96 may be on the atmospheric side of the loadlock, and opening 98
may be on the transfer chamber side of the loadlock.
[0041] The lower plate 76 of the cassette 50 preferably has a
support structure including the supports 78, 80 thereon for
supporting a substrate 82. The cooling plate 52, (located above the
lower plate 76) may include apertures 84, 86 through which the
supports 78, 80 may extend to support the substrate 82 in the lower
slot 53. The middle plate 56 preferably has a support structure
including supports 88, 90 thereon for supporting a substrate 92 in
the upper slot 51. Above the middle plate 56 (and the substrate 92)
lies the upper plate 54 and heating device 94. The heating device
94 may include, for example, a resistance element or a heating
lamp. Alternative embodiments may omit the upper plate 54 and/or
the heating device 94.
[0042] As illustrated in FIG. 6a, the heating device 94 may fit
into a recess in the upper plate 54 so that it moves with the
cassette 50 and is always positioned close to the upper support
structure. Alternatively, the heating device 94 may be positioned
above the upper plate 54 as illustrated in FIG. 2 or at some other
position in the loadlock. One preferred use for the heating device
is to preheat an unprocessed substrate prior to transferring the
substrate to other chambers. Preheating the substrate may free up
one or more processing chamber positions in the system which would
otherwise be used as heating chambers to heat the unprocessed
substrate. By preheating the substrate in the loadlock, such
heating chambers may be eliminated. Embodiments may heat the
substrate to a desired temperature depending on the particular
processing operation such as, for example, a temperature in the
range of approximately 100 degrees Celsius to 500 degrees Celsius
or higher. It may be possible to also use the loadlock for other
types of heating operations, such as annealing or ashing, if
desired. For certain types of high temperature processing or
processing in which the substrate is heated in between other
processing steps, separate heating chambers may still be
required.
[0043] FIGS. 7a-f schematically illustrate several components of a
loadlock as used during one possible processing embodiment. Certain
component sizes and shapes have been altered relative to earlier
figures for illustrative purposes. The components illustrated
include the lower plate 76, the cooling plate 52, and the middle
plate 56. Lower supports 78, 80 are coupled to the lower plate and
upper supports 88, 90 are coupled to the middle plate 56. The lower
plate 76 and middle plate 56 are coupled to one another to form
cassette 50 as indicated by the dashed lines. The lower supports
78, 80 extend through apertures in the cooling plate 52. An
atmospheric robot (not shown in FIGS. 7a-f) delivers into and
removes substrates from the load lock through atmospheric opening
96 and door 68, and a transfer chamber robot (not shown in FIGS.
7a-f) removes from and delivers substrates into the loadlock
through vacuum opening 98 and door 99. As seen in FIGS. 7a-f, the
cooling plate 52 is coupled to the frame 64 and does not move
relative to the openings 96, 98. The cassette 50 (which includes
the lower plate 76, lower supports 78, 80, the middle plate 56, and
the upper supports 88, 90), is moveable relative to the openings
96, 98.
[0044] A condition when there are no substrates in the loadlock is
illustrated in FIG. 7a. This may be the condition at the beginning
of a processing cycle. In one embodiment, a processing method
includes supplying an unprocessed substrate 92 to the loadlock. As
shown in FIG. 7b, upper supports 88, 90 are aligned with the
opening 96 and an unprocessed substrate 92 has been inserted into
the loadlock through an atmospheric opening from the direction
indicated by the arrow. Next, the atmospheric opening door 68 is
closed, the loadlock is evacuated and the cassette 50 is raised to
place the lower supports 78, 80 through openings 59 in the cooling
plate 52 and into alignment with the vacuum opening 98 as shown in
FIG. 7c. Vacuum opening door 99 is opened so that a processed
substrate 82 can be delivered from a transfer (or other processing)
chamber (not shown) to the loadlock from the direction shown by the
arrow, and placed on supports 78, 80.
[0045] The cassette 50 may then be lowered to place the processed
substrate 82 onto the cooling plate 52 for cooling, as shown in
FIG. 7d. Preferred embodiments may include structures such as pins
57 extending from the cooling plate 52 into openings 61 in the
bottom of the middle plate 56. The pins 57 may act to ensure proper
alignment of the cooling plate 52 and middle plate 56 as well as
providing a barrier to prevent a substrate from sliding off of the
cooling plate in a lateral direction, which may occur due to a gas
pressure introduced in the chamber during a cooling procedure. As
can be seen in FIG. 7d, the cooling plate 52 and middle plate 56
may be positioned so that the processed substrate 82 is essentially
sandwiched between the plates. This promotes the efficient cooling
of the processed substrate 82. In general, the closer the middle
plate 56 is positioned to the processed substrate 82, the faster
the cooling rate of the processed substrate 82. In one example, a 5
mm gap between the middle plate 56 and the processed substrate 82
provided a cooling rate that was about 5 times faster than a 1 inch
(.about.25 mm) gap.
[0046] FIG. 7d also shows that the unprocessed substrate 92 has
also been placed into alignment for delivery through the vacuum
opening 98 in the direction indicated by the arrow. The unprocessed
substrate is delivered through the vacuum opening and then the
vacuum door 99 is closed and the chamber vented so that another
unprocessed substrate 92' may be placed onto the upper support 88,
90 through the atmospheric opening, from the direction indicated by
the arrow, as illustrated in FIG. 7e. The venting may also be
controlled to promote uniform cooling of the processed substrate
82. The cassette 50 may then be raised to lift the processed
substrate off of the cooling plate 52 and into position to be
removed from the loadlock through the atmospheric opening 96 in the
direction indicated by the arrow, as shown in FIG. 7f.
[0047] It should be appreciated that the above steps may be varied
as desired and that there are numerous different processing schemes
that may be performed according to embodiments of the present
invention. For example, another processing embodiment may include
heating the unprocessed substrate 92 in the loadlock prior to
transferring it to the transfer chamber. In such an embodiment the
heating step is carried out and the heated, unprocessed substrate
92 is preferably delivered through the vacuum opening 98 to the
transfer chamber prior to delivering the processed substrate 82
from the transfer chamber to the loadlock.
[0048] More detailed views of the cassette 50 and the cooling plate
52 are illustrated in FIGS. 8 and 9. The upper plate 54, middle
plate 56, and lower plate 76 may be coupled together through side
portions 77, 79. The side portions 77, 79 may be separate pieces
coupled together using pins 89. Alternatively, the side portions
77, 79 may be a single unit and may be integrated into one or more
of the plates 54, 56 and 76.
[0049] As seen in FIG. 8, the lower supports 78, 80 are supporting
processed substrate 82 above the surface of the cooling plate 52.
This configuration may correspond to a load/unload condition where
a processed substrate 82 is being loaded into or removed from the
loadlock. In this embodiment the processed substrate 82 is
transparent. The supports 78, 80 may have a variety of structures
that can support a substrate including, but not limited to a pin,
bolt, screw or peg-like shape. The tips of the supports may also
have variety of structures. For example, as illustrated in FIGS.
7a, the tip of the supports 78, 80, 88, 90 are rounded, whereas in
FIG. 9, the tips of the supports 78, 80 are flat and include
openings 81. As illustrated in FIGS. 8 and 9, one embodiment
preferably includes four outer pins 78 and two central pins 80.
[0050] FIG. 9 illustrates the position of the lower supports 78, 80
after the supports have been lowered to place the processed
substrate 82 on the surface of the cooling plate 52. The cooling
plate 52 may be designed to have one or more zones for
preferentially controlling the temperature of a substrate thereon.
This may be accomplished by providing a pattern of one or more
channels or grooves 104 on its upper surface. The location and
number of grooves 104 is designed to control the contact area
between a substrate and the surface of the cooling plate 52 to
permit better temperature control during cooling. For example, if
more grooves 104 per unit area are located near the periphery of
the cooling plate 52 than near the center, an increased surface
area of the substrate will contact the cooling plate 52 near its
center. If the center is a heat transmissive material such as, for
example, a metal, then more heat will be transmitted from the
center of the substrate. The grooves 104 are designed to counter
the thermal losses, which typically occur more quickly near the
periphery of the substrate. This leads to a more uniform
temperature distribution across the substrate during cooling. In
one embodiment the grooves 104 may have a width of about 6 mm and a
depth of about 1 mm. Other dimensions may be suitable for
particular applications.
[0051] Embodiments may also include a one or more coolant carrying
channels incorporated into or attached to portions of a cooling
plate and a middle plate in order to remove heat from the plate
quickly. The coolant carrying channels may be distributed along the
cooling plate as desired to yield different cooling characteristics
for different portions of the cooling plate, in order to provide a
more uniform temperature distribution across a substrate. FIG. 10
illustrates a cross-sectional view of an embodiment of a cooling
plate 106 including a number of grooves 104 and a coolant carrying
channel 108 formed therein. FIG. 11 illustrates an embodiment of a
cooling plate 110 including grooves 104 and a pipe or tube 112 as a
coolant carrying channel connected (permanently or detachably) to
the bottom of the cooling plate 110. In certain embodiments, the
middle plate acts like a second cooling plate to assist in cooling
a processed substrate. FIG. 12 illustrates an embodiment of a
middle plate 116 including a coolant carrying channel 118 therein.
FIG. 13 illustrates an embodiment of a middle plate 120 having a
pipe or tube 122 as a cooling carrying channel connected
(permanently or detachably) to the top of the middle plate 120.
[0052] Embodiments may also include a cooling plate and a middle
plate each including a surface having multiple characteristics such
as a different surface finish in different locations. For example,
a dull and/or black finish (or other dark color finish) may
accelerate cooling due to greater heat absorption than a reflective
and/or smooth finish, which will reflect more heat back to the
substrate. Anodizing or bead blasting all or part of the cooling
plate can form a preferred high emissivity finish that may
accelerate cooling. As illustrated in FIG. 14, for example, the
surface of a plate 130 (such as a cooling plate and/or a middle
plate) may contain a high emissivity central area 131. As seen in
FIG. 14, the high emissivity central area 131 of the plate 130 is
viewed through a transparent substrate 132. The substrate 132
preferably has a larger size than the high emissivity area 131 (and
a smaller size than the plate 130). In certain embodiments, in
order to more uniformly cool the substrate it is desirable to not
provide the high emissivity region 130 near the edges of the
substrate 132. This is because the edges of the substrate 132 tend
to cool more quickly than its center area, so providing the high
emissivity region 130 over the entire surface would lead to the
edges of the substrate 132 cooling much faster than the central
area. Such non-uniform cooling can cause undesirable stresses
and/or warping of the substrate 132.
[0053] The top and bottom covers 70, 72 (FIG. 2) of the loadlock 30
may include flanges 116 and o-rings 118, which are used to mount
the top cover 70 and lower cover 72 to the loadlock frame member
64. Top cover 70 may also include inlet/outlet vent 120, which may
include a gas delivery pipe or tube through which a gas may be
delivered to the interior of the loadlock. A variety of gases may
be delivered to the loadlock depending on the processing operation
(cooling, annealing, preheating, ashing, etc.) to be carried out.
In certain embodiments, it is preferred that a cooling gas is
delivered into the chamber upon venting to assist in cooling a
processed substrate on the cooling plate 52. Preferred cooling
gases for use in the chamber include nitrogen and/or helium. Other
inert gases including, but not limited to argon and neon could also
be used. Certain embodiments utilize a mixture of helium and
nitrogen at pressures of about 754-759 Torr nitrogen and about 1-6
Torr helium. In one preferred embodiment, cooling gas is supplied
to the chamber by venting the chamber at 3 Torr helium and 757 Torr
nitrogen. This cooling scheme has been observed to provide a
uniform and rapid cooling. Preferred embodiments may also include
helium alone as the cooling gas due to its inert nature and thermal
conductivity. It is preferred that the substrate be cooled with a
uniformity of about 100 degrees Celsius or less along the
substrate, even more preferably about 50 degrees Celsius or less.
If desired a filter 122 (FIG. 2) may be positioned near the top of
the loadlock to filter out undesirable particles and to promote
uniform distribution of gas throughout the loadlock chamber. The
filter 122 may be held in place by holder 124 and may be adjusted
using screw 126.
[0054] In certain preferred embodiments, the lower supports 78, 80
extend through apertures in the cooling plate 52. Alternative
embodiments may utilize a lower support extending adjacent to the
cooling plate instead of through the apertures in the cooling
plate. As illustrated in FIG. 15, one such embodiment may include a
support 136 adjacent to a cooling plate 138 including one or more
movable arms 140 which may be lowered into one or more grooves 142
in the cooling plate 138 in order to deposit a processed substrate
82 on the upper surface of the cooling plate 138.
[0055] Other embodiments may include a loadlock having components
similar in some ways to those illustrated in 6a, but including a
single opening for transferring substrates in and out of the
loadlock and between the loadlock and a transfer chamber.
[0056] Several embodiments of cluster processing systems according
to embodiments of the present invention are illustrated in FIGS. 16
and 17. FIG. 16 illustrates a system 158 which, according to one
embodiment, includes a supply of unprocessed substrates from an
unprocessed substrate cassette 162, which may be supplied to the
loadlock 160 from a substrate cassette and robot station 164 one at
a time using a robot 166. The loadlock 160 may have a similar
structure to the loadlock 30 shown in FIGS. 2-4 Once an unprocessed
substrate is inside the loadlock 160, the loadlock 160 is evacuated
and the unprocessed substrate is transported to the transfer
chamber 168 having a second robot 170 therein. Once inside the
transfer chamber 168, the unprocessed substrate is transferred
between chambers for processing. In one embodiment, the substrate
is first transported to chamber 172 for heating, then back to the
transfer chamber 168, and then to another processing chamber 174,
which may be any other type of processing chamber such as, for
example, a chemical vapor deposition (CVD) chamber, a physical
vapor deposition (PVD) chamber, or an etching chamber. After
treatment in a processing chamber 174, the substrate may be
transported to the transfer chamber 168 and then to another
processing chamber 174. When the substrate is fully processed as
desired, it is then delivered from the final processing chamber to
the transfer chamber 168 and back to the loadlock 160. The
processed substrate may then be cooled in the loadlock 160. Cooling
may take place while the loadlock 160 is evacuated and may also
take place as the loadlock 160 is vented. Once venting is complete
and the processed substrate is sufficiently cooled (such as, for
example, to about 100 degrees Celsius), the processed substrate may
be removed from the loadlock 160 using the robot 166 and delivered
to a processed substrate cassette 176 at the station 164.
[0057] Another embodiment of a processing system 178 in some ways
similar to that of FIG. 16 is illustrated in FIG. 17. However, the
embodiment of FIG. 17 includes two loadlocks 160 and five
processing chambers 174, as well as one heating chamber 172 and
transfer chamber 168 having a robot 170 therein. This embodiment
may be particularly useful when the processing can be carried out
quickly and throughput can be increased by supplying more
substrates to the system. As illustrated, the system 178 includes a
larger station 165 having more cassettes 162, 176 for supplying
unprocessed substrates to the loadlocks 160 and for accepting
processed substrates from the loadlocks 160 using the robot 167.
Certain embodiments of the present invention may include a heater
within the loadlock. When using such embodiments, it may be
possible to eliminate the heating chamber such as heating chamber
172 of FIGS. 16 and 17. In such a case an additional processing
chamber 174 may be used if desired, and if only one loadlock 160 is
used, the system will have seven processing chambers. Depending on
the desired processing steps and the platform used, any number of
processing chambers, loadlocks, and heating chambers may be used.
Certain platforms may also utilize more than one transfer
chamber.
[0058] Selected embodiments of the present invention can provide
one or more of a number of advantages. For example, in certain
embodiments, a single loadlock chamber can be used for both cooling
processed substrates and heating unprocessed substrates. Various
features also enable a large glass substrate to be cooled or heated
quickly, thereby increasing the throughput of the system. Various
aspects of the loadlock design may help to control the temperature
of a substrate on the cooling plate to provide a more uniform
temperature across the substrate or to provide a particular
temperature distribution across the substrate. For example, the
heating device 94 may in certain embodiments be used during a
cooling operation in order to control the temperature distribution
across a substrate. By controlling the insulative properties of the
middle plate 56 and/or other portions of the loadlock, heat from
the heating device 94 may be transmitted to a portion of a
substrate in order to control its temperature. In one embodiment,
by keeping the outer edges of the substrate at a higher temperature
than the middle regions of the substrate, the outer edges can be
placed into compression as the substrate cools, thus minimizing the
risk of edge failures. Cooling the outer edges of a substrate at a
slower rate than the interior portions of the substrate may be
accomplished in certain embodiments by directed an amount of heat
from the heating element 94 around the edges of the middle plate 56
to contact the outer edge regions of the processed substrate on the
cooling plate 52.
[0059] In addition, the time spent waiting during processed
substrate cooling and unloading from the loadlock can be
significantly shorter when using a dual substrate cassette
according to embodiments of the present invention, as compared to
using a loadlock having a larger cassette holding, for example, 12
substrates. In a system having a cassette holding 12 substrates in
the loadlock, it may take approximately 2 minutes for the system to
vent and another 8 minutes to unload the substrates from the
loadlock after it has been vented when using a robot arm to unload
each substrate. Certain embodiments of the present invention (which
have a considerably smaller interior chamber volume than a loadlock
having a 12 substrate cassette therein) may preferably accomplish
both the venting and removal of a processed substrate in a time of
up to about a minute, or more preferably about 30 seconds. In
addition, certain embodiments which have a heating element in the
loadlock can heat a substrate quickly due to the relatively small
interior volume in the loadlock and because the substrate can be
located close to the heater. Preferred embodiments can heat the
substrate in a time of less than one minute, or more preferably
about 30 seconds.
[0060] The faster venting, substrate removal, and/or heating time
provided by selected embodiments of the present invention offer
several advantages. First, the throughput of the system may, for
certain types of processing, be higher. Certain embodiments can
permit a fast tact time, which is the time it takes one substrate
to enter the system, be processed, and then exit the system.
Second, the need to use a robot having the greatest speed possible
(for unloading the substrates) may be reduced because the system
can have less down time. Using a slower speed robot may improve the
reliability of the processing system.
[0061] Depending on the processing steps to be carried out, it may
in certain embodiments be desirable to have 0 or 1 substrate in the
loadlock at any one time. In other embodiments, it may be desirable
to have up to 2 substrates in the loadlock at any one time.
Alternative embodiments may permit more than 2 substrates to be
located in the loadlock at any one time. Selected embodiments of
the present invention may achieve a high throughput despite having
fewer substrates in the system at any one time than in certain
other systems. For example, one batch processing system having a
substrate cassette in the loadlock may at certain times have
approximately 40 substrates in the system, with 12 substrates in
the loadlock, 12 substrates in a heating chamber, and 16 substrates
being processed in the other system chambers. Matching the number
of substrates in the loadlock and heating chamber can permit smooth
substrate transferring due to a symmetrical layout of the system. A
system according to certain preferred embodiments of the present
invention may at certain times have approximately 15 substrates in
the system, with 1 in the loadlock, 8 in a heating chamber, and 6
substrates in the other system chambers. These numbers may vary
considerably depending on the configuration of the various chambers
in the system. Depending on the exact processing steps and their
duration, due to the faster insertion and removal of substrates,
certain embodiments of the present invention may have a higher
overall throughput per time period than a system that having a
12-substrate cassette in the loadlock.
[0062] The smaller size of the loadlock dual substrate cassette of
certain embodiments of the present invention relative to the
loadlock cassettes used in some other systems also enables to
loadlock to be fabricated from less material and to utilize smaller
vacuum, elevator, power components and the like. These smaller
components can make the system considerably less expensive than
larger systems including multiple substrate cassettes within the
loadlock.
[0063] Typical processing pressures used in the various chambers
described above may range from about 10-8 Torr to several Torr and
vary depending on the chamber and the process steps (PVD, CVD,
etching, annealing, etc) being performed. It is generally desired
that the pressure difference between adjacent chambers be kept to a
minimum or controlled when adjacent chambers are in communication
with each other in order to minimize contamination.
[0064] Embodiments of the present invention also include other
types of processing systems such as linear systems in which a
substrate may be transported from a loadlock to one or more
processing chambers sequentially and then to the same or another
loadlock, depending on the system layout.
[0065] It will, of course, be understood that modifications of the
present invention, in its various aspects, will be apparent to
those skilled in the art. A variety of additional embodiments are
also possible, their specific designs depending upon the particular
application. As such, the scope of the invention should not be
limited by the particular embodiments herein described but should
be defined by the claims.
* * * * *