U.S. patent application number 09/918198 was filed with the patent office on 2001-11-22 for apparatus for storing and moving a cassette.
Invention is credited to Belitsky, Victor, Gantvarg, Evgueni, Perlov, Ilya.
Application Number | 20010043849 09/918198 |
Document ID | / |
Family ID | 22747069 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010043849 |
Kind Code |
A1 |
Perlov, Ilya ; et
al. |
November 22, 2001 |
Apparatus for storing and moving a cassette
Abstract
A cassette stocker includes a plurality of cassette storage
shelves positioned adjacent a cleanroom wall above a cassette
docking station, and a cassette mover to carry a cassette between
the shelves and the docking station. An interstation transfer
apparatus includes an overhead support beam and a transfer arm
adapted to carry a cassette between processing stations.
Inventors: |
Perlov, Ilya; (Santa Clara,
CA) ; Gantvarg, Evgueni; (Santa Clara, CA) ;
Belitsky, Victor; (Sunnyvale, CA) |
Correspondence
Address: |
PATENT COUNSEL
APPLIED MATERIALS, INC.
Legal Affairs Department
P.O. BOX 450A
Santa Clara
CA
95052
US
|
Family ID: |
22747069 |
Appl. No.: |
09/918198 |
Filed: |
July 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09918198 |
Jul 30, 2001 |
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09201737 |
Dec 1, 1998 |
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6283692 |
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Current U.S.
Class: |
414/222.01 |
Current CPC
Class: |
H01L 21/68707 20130101;
H01L 21/67769 20130101; Y10S 414/14 20130101; H01L 21/67167
20130101 |
Class at
Publication: |
414/222.01 |
International
Class: |
B65G 049/07 |
Claims
What is claimed is:
1. An apparatus for storing cassettes, comprising: a plurality of
cassette storage shelves; and a cassette mover to carry a cassette
between the shelves and a docking station, the cassette mover
including a support member positioned in front of the shelves and
movable in a path adjacent to the shelves, and an end effector
configured to engage the cassette, the end effector movably
connected to the support member.
2. The apparatus of claim 1, wherein the shelves are configured to
be positioned adjacent a cleanroom wall.
3. The apparatus of claim 2, wherein one or more of the shelves are
positioned above the docking station.
4. The apparatus of claim 1, further comprising a frame supporting
the cassette storage shelves and the support member.
5. The apparatus of claim 4, wherein the frame substantially fits
below the docking station.
6. The apparatus of claim 1, wherein a lower end of the support
member is slidably connected to a frame.
7. The apparatus of claim 6, wherein the end effector is joined to
a first slider which slidably engages a first, vertical guide
joined to the support member.
8. The apparatus of claim 7, wherein the support member is joined
to a second slider which slidably engages a second, horizontal
guide joined to the frame.
9. The apparatus of claim 8, further comprising a first lead screw
engaging the first slider and a first drive motor to rotate the
first lead screw and drive the first slider along the first guide
to move the end effector vertically.
10. The apparatus of claim 9, further comprising a second lead
screw engaging the second slider and a second drive motor to rotate
the second lead screw and drive the second slider along the second
guide to move the support member and the end effector
horizontally.
11. The apparatus of claim 1, wherein the shelves are arranged in a
vertical column above the docking station.
12. The apparatus of claim 1, wherein the end effector includes a
hook-shaped finger adapted to engage a bottom surface of a flange
on a top of the cassette.
13. The apparatus of claim 1, wherein each shelf includes a
plurality of pins that project vertically from the shelf to engage
corresponding indentations in the underside of the cassette.
14. An apparatus for storing cassettes, comprising: a plurality of
cassette storage shelves positioned adjacent a wall above a
plurality of cassette docking stations; and a cassette mover to
carry a cassette between the shelves and the docking stations, the
cassette mover including a support member positioned in front of
the shelves and movable in a plane parallel to the wall, and an end
effector configured to engage the cassette, the end effector
slidably connected to the support member.
15. The apparatus of claim 14, wherein the shelves are arranged in
a vertical column above each docking station.
16. The apparatus of claim 14, wherein adjacent vertical columns of
shelves are separated by a vertical channel, and the cassette mover
is configured to transport a cassette to a selected support shelf
by moving the cassettes vertically through the channel to position
the cassette substantially adjacent and above the selected support
shelf, and then horizontally to position the cassette over the
selected support shelf.
17. A semiconductor processing station, comprising: a processing
system to perform a fabrication step on a substrate; an interface
wall separating the processing system from a cleanroom; a docking
station located in the cleanroom to support a cassette; an opening
in the interface wall; a wafer transfer robot to transfer the
substrate through the opening between the docking station and the
processing system; a loading platform located in the cleanroom
adjacent the docking station; and a cassette stocker located in the
cleanroom, the cassette stocker including, i) a plurality of
shelves aligned in a vertical column above the docking station, and
ii) a cassette mover to carry a cassette between the shelves, the
loading platform, and the docking station, the cassette mover
including a support member positioned in front of the shelves and
movable in a path adjacent to the shelves, and an end effector
slidably connected to the support member and configured to engage
the cassette.
18. A method of operating a processing station, comprising: storing
a plurality of cassettes on a plurality of cassette storage shelves
adjacent a cleanroom wall above a docking station; carrying one of
the cassettes to the docking station with a cassette mover;
removing a substrate from the cassette; and returning the cassette
to the cassette storage shelves with the cassette mover.
Description
[0001] This application is a division of U.S. patent application
Ser. No. 09/201,737 filed Dec. 1, 1998.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to substrate
processing, and more particularly to an apparatus for storing and
moving substrate cassettes.
[0004] 2. Background of the Related Art
[0005] Semiconductor devices are made on substrates, such as
silicon wafers or glass plates, for use in computers, monitors, and
the like. These devices are made by a sequence of fabrication
steps, such as thin film deposition, oxidation or nitration,
etching, polishing, and thermal and lithographic processing.
Although multiple fabrication steps may be performed in a single
processing station, substrates must be transported between
different processing stations for at least some of the fabrication
steps.
[0006] Substrates are stored in cassettes for transfer between
processing stations and other locations. Although cassettes may be
carried manually between processing stations, the transfer of
cassettes is typically automated. For example, a cassette may be
transported to a processing station in an automatic guided vehicle
(AGV), and then loaded from the AGV onto a loading platform in the
processing station by a robot. Another robot may extract a
substrate from the cassette and transport it into a processing
chamber at the processing station. When the fabrication steps are
complete, the substrate is loaded back into the cassette. Once all
of the substrates have been processed and returned to the cassette,
the cassette is removed from the loading platform and transported
to another location by the AGV.
[0007] In order to ensure that the processing equipment does not
sit idle, a nearly continuous supply of unprocessed substrates
should be available at the processing station. Unfortunately, many
processing stations can hold only a single cassette at the loading
platform. Therefore, once all of the substrates in the cassette
have been processed, the cassette must be quickly replaced, either
manually or by an AGV, with a new cassette containing unprocessed
substrates. Unfortunately, running such a just-in-time cassette
inventory system requires either significant operator oversight or
a large number of AGVs, thereby increasing the costs of the
fabrication facility.
[0008] Therefore, there is a need for a method and apparatus which
continuously supplies substrate cassettes to a processing system so
that system down time is reduced or eliminated.
SUMMARY OF THE INVENTION
[0009] The present invention provides a method and apparatus for
storing multiple cassettes at a processing station, ensuring that a
nearly continuous supply of unprocessed substrates is available for
processing and that the processing equipment does not sit idle.
Multiple cassettes can be stored at a processing station in a front
end support frame and a cassette can be moved to a docking station
where substrates are extracted and transferred to the processing
equipment. An automation system is mounted or otherwise disposed on
the frame to transfer cassettes between docking stations or between
processing stations. The apparatus does not increase the footprint,
i.e., the required area on the cleanroom floor, of the processing
station. In another aspect of the invention, cassettes can be
transported between different processing stations without the use
of an AGV.
[0010] In one aspect of the invention, an apparatus is provided
which includes a front end frame having one or more substrate
transfer stations and multiple cassette storage stations. An
automated transfer assembly is preferably disposed adjacent the
transfer stations and the storage stations to move cassettes
between the storage stations and the transfer stations.
Additionally, an automated transfer assembly can be located between
processing stations to transfer cassettes between processing
stations without the need for manual or AGV assistance.
[0011] In another aspect of the invention, a method is provided for
delivering a continuous supply of cassettes to a processing system.
The method preferably includes providing at least one transfer
station and multiple storage stations and moving cassettes between
the storage stations and the transfer stations to ensure that
substrates are continually supplied to the processing system.
Additionally, a method is provided for transferring cassettes
between processing stations to continue the processing sequence
without the need for manual or AGV assistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic top view of a processing station
according to the present invention.
[0013] FIG. 2 is a schematic perspective view of a cassette for
holding substrates.
[0014] FIG. 3 is a schematic perspective view of a cassette stocker
according to the present invention.
[0015] FIG. 4A is a schematic front view of the cassette stocker of
FIG. 3.
[0016] FIG. 4B is a schematic front view of the cassette stocker of
FIG. 4A with a plurality of cassettes.
[0017] FIG. 5A is a schematic side view of the cassette stocker of
FIG. 3.
[0018] FIG. 5B is a schematic side view of the cassette stocker of
FIG. 5A with a plurality of cassettes.
[0019] FIG. 6 is a schematic top view of an end effector located
over a docking station.
[0020] FIGS. 7A, 7B and 7C are schematic perspective views
illustrating the end effector lifting and moving a cassette.
[0021] FIGS. 8A and 8B are schematic front views of the cassette
stocker illustrating the path the end effector takes in moving a
cassette between a loading platform and a cassette docking
platform.
[0022] FIG. 9 is a schematic front view of two loading and storage
stations connected by an interstation transfer mechanism.
[0023] FIG. 10 is a schematic perspective view of another
embodiment of a cassette stocker according to the present
invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0024] In the following description, the term "substrate" broadly
covers any object that is being processed in a semiconductor device
processing system. The term "substrate" includes, for example,
semiconductor wafers, flat panel displays, glass plates or disks,
and plastic workpieces.
[0025] FIG. 1 is a top view of a processing station 20 of the
present invention in which one or more substrates 10 are processed.
The processing station 20 has a front-end staging area 22 which is
separated from a loading and storage area 24 by a cleanroom wall
26. Cleanroom wall 26 separates a cleanroom 28, where loading and
storage area 24 is located, from a gray area 30, where a processing
system 32 is housed. The loading and storage area 24 is where
cassettes of substrates are delivered and loaded/unloaded into/from
the processing station 20. Processing system 32 may include one or
more load lock chambers 34, a central transfer chamber 36, and a
plurality of processing chambers 38. Inside processing chambers 38,
the substrate may be subjected to a variety of fabrication steps,
such as thin film deposition, oxidation, nitration, etching,
thermal processing or lithographic processing. For the purposes of
the invention, the processing system and staging area illustrated
in FIG. 1 are merely representative. The processing system could
have just a single processing chamber, or it could be a device,
such as a chemical mechanical polisher, that does not include any
processing chambers. In addition, the processing system could
perform metrology instead of or in addition to the fabrication
steps.
[0026] Referring to FIG. 2, one or more substrates 10 are brought
to the loading and storage area 24 of the processing station in a
cassette 100. Substrates 10 are supported in cassette 100 in a
generally parallel horizontal configuration by slot ridges 102.
Substrates may be loaded and unloaded from cassette 100 through an
entry port 103 located in a generally flat front face 106 of the
cassette. A removable cassette door 104 may be secured in entry
port 103 to prevent the substrates from being exposed to
contaminants when the cassette is moved between processing stations
or stored outside a processing station. Each cassette 100 also
includes three cylindrical indentations 108 (shown in phantom and
only two of which are visible in FIG. 2) formed in an underside 110
of the cassette. When cassette 100 is stored at the processing
station, three support pins will fit into indentations 108 to
support the cassette. Two handles 112 (only one is shown in this
perspective view) which project from sidewalls 114 may be used to
manually carry the cassette. A generally rectangular flange 116
having an L-shaped cross-section projects from a top surface 118 of
the cassette. As discussed below, a robotic cassette mover at the
processing station may manipulate the cassette by means of flange
116.
[0027] Referring to FIGS. 1 and 3-5B, loading and storage area 24
of processing station 20 includes a cassette loading platform 52,
two cassette docking or substrate transfer stations 40 located on
either side of loading platform 52, and a cassette stocker or
storage stations 50 (only partially illustrated in FIG. 1 so that
docking stations 40 may be seen) for storing cassettes at the
processing station and moving the cassettes to and from loading
platform 52 and docking stations 40.
[0028] A cassette may be placed onto or removed from loading
platform 52 either manually or by an AGV. From the loading
platform, the cassette may be moved to one of docking stations 40
or into cassette stocker 50. Loading platform 52 has generally the
same perimeter shape as a cassette. Three support pins 54 (only two
are seen in the side view of FIG. 5A) project vertically from the
loading platform to mate with the indentations in the underside of
the cassette to support the cassette on the loading platform.
[0029] To transfer substrates through the cleanroom wall, cassettes
100 (shown in phantom in FIG. 1) may be positioned at one or both
docking stations 40. Each docking station 40 includes a docking
platform 42 to support a cassette, an opening 46 formed through
cleanroom wall 26, a movable door 44 which seals opening 46 when a
substrate is not to be transferred through opening 46 or a cassette
is not positioned on docking platform 42, and a mechanism to unlock
cassette door 104 and retract the door into front-end staging area
22 to provide horizontal access to the substrate. A description of
docking station 40 may be found in U.S. patent application Ser. No.
09/012,323, entitled A WAFER CASSETTE LOAD STATION, filed Jan. 23,
1998, by Eric A. Nering, et al., assigned to the assignee of the
present invention, the entire disclosure of which is incorporated
herein by reference.
[0030] Cassette stocker 50 includes a frame 60 that supports one or
more storage racks 58 (not illustrated in FIG. 1 so that the
docking stations may be shown), and a robotic cassette mover 56 to
move the cassettes between the storage rack, the loading platform,
and the docking platforms. Frame 60 may be bolted to the floor of
cleanroom 28 and/or secured to the cleanroom wall 26. The frame 60
is at least partially disposed below the docking platforms 42 and
loading platform 52 so that the footprint of processing station 20
is not increased.
[0031] Storage rack 58 may include a vertical column of support
shelves above each of the two docking stations 40. Each column may
include, for example, one, two, three or more individual support
shelves. Thus, storage rack 58 shown in FIGS. 3-5b provides storage
space for six cassettes 100 in support shelves 62a-62f (see FIG.
4B). Each support shelf, such as support shelf 62a, may be a
horizontally oriented plate having substantially the same perimeter
shape as the cassette. Three support pins 64 (only two are shown in
the side view of FIG. 5A) project vertically from the support shelf
and are positioned to mate with receiving indentations 108 in the
underside of the cassette. Two vertical posts 66 may be used to
secure the outer edge of each support shelf 62a-62f to frame 60.
Additionally, the support shelves could be secured to the cleanroom
wall for additional support.
[0032] Robotic cassette mover 56 is used to move cassettes between
the storage shelves, the loading platform and the docking
platforms. The robotic cassette mover includes a vertically movable
end effector 72 which is attached to a horizontally movable support
strut 74. The support strut 74 permits arbitrary horizontal
movement of end effector 72 in a plane parallel to cleanroom wall
26. The bottom of support strut 74 may be secured to a lateral
slider 76 which can move horizontally along a horizontal guide 78
that is attached to or formed as part of frame 60. The lateral
slider 76 may be driven from side-to-side by a horizontal lead
screw 80, which is rotated by a horizontal drive motor 82. The
horizontal drive motor 82 may be secured to frame 60. Similarly,
end effector 72 may be attached to a vertical slider 84 which can
slide vertically along a vertical guide 86 attached to or formed as
part of support strut 74. The vertical slider 84 may be driven up
and down by a vertical lead screw 87 (shown in phantom in FIGS.
4A-5B) which may be rotated by a vertical drive motor 88. The
vertical drive motor may be supported by lateral slider 76.
Horizontal drive motor 82 and vertical drive motor 88 may be
connected to a control system (not shown), such as a programmable
digital computer, to control the vertical and horizontal motion of
end effector 72. The actuators which drive the movement of the end
effector may include stepper motors, pneumatic actuators and other
devices known to impart movement in a controllable manner. In
addition, a belt drive assembly or other known mechanism can be
utilized to drive the sliders both vertically and horizontally.
[0033] Referring to FIG. 6, end effector 72 projects horizontally
from support strut 74 towards cleanroom wall 26. The end effector
includes a generally flat, hook-shaped finger 90 that defines a
rectangular gap 92 which is open on one side of the end effector.
The end effector is adapted to engage a portion of a cassette
through the use of the open end of the end effector.
[0034] Referring to FIG. 7A, in order to transport cassette 100,
end effector 72 is vertically positioned between flange 116 and top
surface 118 of cassette 100. Referring to FIG. 7B, the end effector
is moved laterally so that a base 117 of flange 116 fits into gap
92. Finally, referring to FIG. 7C, end effector 72 is moved
vertically upwards so that an inner rim 94 of the end effector
contacts an underside 119 of flange 116 to lift the cassette. The
end effector may then be moved laterally to carry cassette 100 to
another support shelf or platform.
[0035] Referring to FIG. 8A, a cassette may be transported from
loading platform 52 to a support shelf, such as support shelf 62b.
With support strut 74 positioned to the side of loading platform
52, a cassette 100 is loaded onto the loading platform, either
manually or by an AGV. To lift the cassette off loading platform
52, end effector 72 is positioned to the left of the cassette at a
vertical height between upper surface 118 of the cassette and the
lower surface of flange 116. The support strut 74 moves rightwardly
until end effector 72 engages the support flange (phantom line A).
Then, the end effector moves upwardly to raise the cassette off of
the loading platform (phantom line B). To move the cassette to one
of the support shelves, e.g., support shelf 62b, end effector 72
raises the cassette until it is generally aligned above the support
shelf 62c, with sufficient vertical clearance to permit the
underside of the cassette to move horizontally over support pins 64
(phantom line C). Then support strut 74 is moved leftwardly to
position the cassette over the support shelf, and the end effector
moves downwardly until the cassette rests on support pins 64
(phantom line D). The end effector may be withdrawn by moving it
leftwardly until it clears the flange, and then moving it upwardly
and rightwardly between the top of the flange and the bottom of
support shelf 62a (phantom line E).
[0036] Referring to FIG. 8B, in order to remove the cassette from
support shelf 62b, these steps are generally repeated in reverse
order. Specifically, end effector moves leftwardly between the top
of flange 116 and the bottom of support shelf 62a (phantom line F),
downwardly until it is located at a vertical position between the
top surface of the cassette and the underside of the flange
(phantom line G), and rightwardly until it engages the flange
(phantom line H). Then the end effector moves upwardly to lift the
cassette off the support plate and then rightwardly to carry the
cassette into the vertical channel between the storage racks
(phantom line I). From this position, the cassette may be moved up
or down and then left or right to a new storage shelf, to one of
the docking platforms, or to the loading platform.
[0037] In the embodiments described in FIGS. 7A-8B, hook-shaped
finger 90 of end effector 72 curves to the right so that
rectangular gap 92 is open on the right. Of course, if hook-shaped
finger 90 curved to the left so that rectangular gap 92 was open on
the left, then the relative lateral motion of the end effector to
engage and disengage the cassette would be reversed. For example,
to lift the cassette from a support shelf, the end effector would
be positioned on the right side of the cassette and moved to the
leftwardly to engage the flange.
[0038] In operation, a cassette 100 is transported to processing
station 20 and placed on loading platform 52, e.g., manually or by
an AGV. The robotic cassette mover 56 transports the cassette from
the loading platform to one of the docking stations, which aligns
the front face of the cassette with docking station door 44, and
then retracts docking station door 44 and cassette door 104 so that
entry port 103 mates with opening 46 in cleanroom wall 26. A wafer
handling robot 48 in front-end staging area 22 extracts the
substrates from the cassette through opening 46 and inserts them
into one of the load lock chamber 34. A robot 39 in transfer
chambers 36 moves substrates between the load lock and the
processing chambers. When the fabrication steps are completed,
wafer handling robot 48 extracts the substrate from one of the lock
load chambers, and returns it to cassette 100 through opening 46.
Once all of the substrates have been processed, cassette door 104
is closed, the cassette is moved to storage rack 58 or loading
platform 52, and a new cassette containing unprocessed substrates
is loaded into the docking station.
[0039] Referring to FIG. 9, an interstation transfer apparatus 120
may be used to move cassettes between adjacent processing stations
20' and 20", thereby eliminating the need for AGVs or manual
transport. Interstation transfer apparatus 120 includes an overhead
support beam 122 which may be secured to posts 66' and 66" of
adjacent cassette stockers 50' and 50". A transfer arm 124 may be
attached to a slider 126 that moves horizontally along a guide 127
that is attached to or formed as part of support beam 122. The
slider may be moved horizontally by a lead screw 130 which may be
rotated by a horizontal drive motor 132. An end effector 128 may be
connected to transfer arm 124 by a pneumatic actuator 134 to
provide end effector 128 with a short vertical stroke.
[0040] In order to transport the cassettes between adjacent
processing stations, the cassette is moved by robotic cassette
mover 56' to the upper right-hand support shelf, i.e., support
shelf 62d', of cassette stocker 50'. End effector 128 moves
horizontally over flange 116, then down to a vertical position
between the bottom of the flange and the top of the cassette. Then
the end effector moves to the right until it engages the cassette
flange. End effector 128 lifts the cassette off support plate 62e',
and horizontal drive motor 132 drives the transfer arm rightwardly
until the cassette is located over the upper left-hand support
shelf 62a" of cassette stocker 50". Finally, the end effector
lowers the cassette onto support shelf 62a" and withdraws.
[0041] Interstation transfer apparatus 120 provides an extremely
simple method of transferring cassettes between adjacent processing
stations. This may be particularly useful where one of the
processing stations is a metrology station (which could be located
entirely inside the cleanroom), since it permits the metrology
measurements to be made without building a metrology apparatus into
the processing equipment and without using a factory automation
system.
[0042] Although cassette stockers 50' and 50" are illustrated as
positioned against the same cleanroom wall, the interstation
transfer apparatus could include rotary mechanisms to allow handoff
between end effectors on different support beams. This would permit
processing stations 20' and 20" to be positioned around the comers
or at opposite walls of the cleanroom.
[0043] The embodiments described above include two storage racks 58
disposed above two docking stations 42 and a loading station 52
disposed between the two docking stations. Preferably, six cassette
support shelves 62(a)-(f) are disposed above the two docking
stations. While this configuration is believed to provide the
highest throughput of substrates in the available space, the
invention also includes a single docking station with one or more
cassette support shelves disposed in proximity to the docking
station. FIG. 10 is a perspective view of one embodiment of the
invention having a single docking station 42 and three storage
shelves 62(a)-(c) disposed above the docking station. Support
shelves 62(b)-(c) are shown in phantom to indicate that only one
support shelf 62(a) could be used to advantage. Components which
from a part of the earlier described embodiments are identified
using the same numbers.
[0044] Substrates may be loaded into the system at either the
docking station position, at any one of the storage shelf positions
or at a loading station 52. The loading station 52 could be
disposed adjacent either a support shelf or the docking station.
The substrate mover system described above in reference to the
other embodiments is utilized with the single stack embodiment and
operates in the same manner except that support shelves disposed in
a single stack eliminate the transfer sequence from the additional
stack.
[0045] Each of the embodiments described herein utilize available
space above docking stations, thereby increasing the storage
capability of the system without increasing the footprint (area
occupied by the system measured in terms of floor space) of the
system. Accordingly, a processing system could utilize any
configuration of the storage device of the present invention
including cassette support shelves disposed adjacent a docking
station. Preferably, a cassette mover is also disposed in proximity
to the support shelves and the docking station to effect transfer
of cassettes between the support shelves and the docking
stations.
[0046] The present invention has been described in terms of a
number of embodiments. The invention, however, is not limited to
the embodiments depicted and described. Rather, the invention is
defined by the claims.
* * * * *