U.S. patent application number 15/382568 was filed with the patent office on 2018-06-21 for magnetic wafer gripper.
The applicant listed for this patent is SolarCity Corporation. Invention is credited to Edward Sung.
Application Number | 20180174876 15/382568 |
Document ID | / |
Family ID | 62561942 |
Filed Date | 2018-06-21 |
United States Patent
Application |
20180174876 |
Kind Code |
A1 |
Sung; Edward |
June 21, 2018 |
MAGNETIC WAFER GRIPPER
Abstract
Systems and methods are described for transferring wafers
between processing steps in the fabrication of solar cells. The
wafers may be processed using a cluster tool including a load-lock,
a plurality of processing modules, and a central robot to transfer
wafers between the plurality of modules. Each module may include a
pedestal including wafer recesses to support the wafers, and puck
recesses for supporting ferromagnetic pucks below the wafers. The
central robot includes electromagnets for attracting the
ferromagnetic pucks toward the electro magnets in order to clamp
the wafers between the ferromagnetic pucks and the
electromagnets.
Inventors: |
Sung; Edward; (Milpitas,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SolarCity Corporation |
San Mateo |
CA |
US |
|
|
Family ID: |
62561942 |
Appl. No.: |
15/382568 |
Filed: |
December 16, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/67742 20130101;
H01L 21/67167 20130101; H01L 21/67709 20130101; C23C 16/4585
20130101; H01L 21/68735 20130101; H01L 21/68785 20130101; H01L
21/67754 20130101; C23C 16/4583 20130101; H01L 31/188 20130101;
H01L 21/68771 20130101; Y02E 10/50 20130101 |
International
Class: |
H01L 21/677 20060101
H01L021/677; H01L 21/683 20060101 H01L021/683; H01L 21/67 20060101
H01L021/67; C23C 16/458 20060101 C23C016/458 |
Claims
1. A method of transporting a wafer comprising: with a robotic arm,
positioning an electromagnet assembly with a contact surface,
proximate to a wafer in a first chamber; and attracting a
ferromagnetic puck positioned on a side of the wafer opposite the
electromagnet assembly with the electromagnet assembly in order to
clamp the wafer between the contact surface and the ferromagnetic
puck.
2. The method of claim 1, wherein the first chamber comprises a
pedestal comprising a puck recess configured to receive the
ferromagnetic puck on the side of the wafer opposite the
electromagnet assembly, and wherein prior to attracting the
ferromagnetic puck, the ferromagnetic puck is located within the
puck recess.
3. The method of claim 2, further comprising: after securing the
wafer against the contact surface, with the robotic arm,
transferring the wafer to a second chamber, the second chamber
comprising a second pedestal with a second puck recess; and with
the robotic arm, positioning the wafer to contact the second
pedestal with the puck within the second puck recess.
4. The method of claim 1, wherein prior to positioning the
electromagnet assembly proximate to the wafer, the wafer is
contacting the ferromagnetic puck.
5. The method of clam 1, wherein the ferromagnetic puck comprises a
ferromagnetic core, and a non-ferromagnetic coating.
6. The method of claim 1, wherein prior to attracting the
ferromagnetic puck, the electromagnet assembly is positioned to
contact the wafer with the contact surface.
7. The method of claim 6, wherein the contact surface comprises a
damping element to damp the contact.
8. The method of claim 1, wherein the first chamber is a processing
chamber, and wherein prior to positioning the electromagnet
assembly proximate to the wafer, a process is performed on a side
of the wafer opposite the ferromagnetic puck.
9. The method of claim 1, further comprising: with the robotic arm,
positioning a second electromagnet assembly with a second contact
surface, proximate to a second wafer in the first chamber; and
attracting a second ferromagnetic puck positioned on a side of the
second wafer opposite the second electromagnet assembly with the
second electromagnet assembly in order to clamp the second wafer
between the second contact surface and the second ferromagnetic
puck.
10. A system comprising: a robotic arm including a first
electromagnet assembly with a first contact surface; a first
ferromagnetic puck; and a pedestal including a first puck recess
configured to receive the first ferromagnetic puck, wherein the
pedestal is configured to support a first wafer, and wherein the
first electromagnet assembly is configured to attract the first
ferromagnetic puck in order to clamp the first wafer between the
first ferromagnetic puck and the first contact surface.
11. The system of claim 10, further comprising: a second
ferromagnetic puck; wherein the robotic arm further comprises a
second electromagnet assembly with a second contact surface,
wherein the pedestal is further configured to support a second
wafer and further includes a second puck recess configured to
receive the second ferromagnetic puck, and wherein the second
electromagnet assembly is configured to attract the second
ferromagnetic puck in order to clamp the second wafer between the
second ferromagnetic puck and the second contact surface.
12. The system of claim 11, wherein the robotic arm is configured
to transfer the first and second wafers from a first processing
chamber to a second processing chamber with the first and second
wafers clamped between the first and second ferromagnetic pucks and
the first and second contact surface.
13. The system of claim 10, wherein the robotic arm further
comprises a plurality of electromagnet assemblies, including the
first electromagnet assembly, arranged in a first grid pattern; and
wherein the pedestal further comprises a plurality of puck
recesses, including the first puck recess, arranged in a second
grid pattern, corresponding to the first grid pattern.
14. The system of claim 10, wherein the first ferromagnetic puck
comprises outside surface composed of a first material, and wherein
the pedestal is composed of the first material.
15. The system of claim 10, wherein the pedestal is located within
a chemical vapor deposition chamber, and wherein the chemical vapor
deposition is configured to deposit material on a first side of the
first wafer with the first ferromagnetic puck positioned in the
first puck recess between a second side of the first wafer,
opposite the first side, and the pedestal.
16. A pedestal in a wafer processing module, comprising: a support
surface configured to support a wafer; and a first puck recess
configured to support a ferromagnetic puck between the pedestal and
the wafer.
17. The pedestal of claim 16, further comprising: a first wafer
recess, wherein the first puck recess is positioned substantially
in the center of the first wafer recess.
18. The pedestal of claim 16, further comprising: a plurality of
wafer recesses, including the first wafer recess; and a plurality
of puck recesses, including the first puck recess, wherein each of
the plurality of wafer recesses include one of the plurality of
puck recesses, and wherein the plurality of wafer recesses are
oriented in a grid pattern, including rows and columns of wafer
recesses.
19. The pedestal of claim 16, wherein the support surface and puck
recess are composed of the same material as an outside surface of
the ferromagnetic puck.
20. The pedestal of claim 16, wherein the pedestal is located
within a chemical vapor deposition chamber.
Description
FIELD
[0001] The described embodiments relate to devices, systems, and
methods that facilitate transfer of wafers during the fabrication
of solar cells. In particular, a carrier-less technology using
ferromagnetic pucks for transferring wafers between a plurality of
processing modules is disclosed.
BACKGROUND
[0002] Advances in photovoltaic technology have helped solar energy
gain mass appeal among those wishing to reduce their carbon
footprint and decrease their monthly energy cost. However, the
fabrication of solar cells, used to make solar panels, typically
includes various processes that are time-consuming and involve
expensive equipment, which can make it costly to mass-produce solar
panels.
[0003] Fabricating solar cells can be made more efficient by
processing many wafers simultaneously. In existing technology,
during processing, for example during the deposition of material, a
plurality of wafers are transferred into a processing chamber for
material deposition using a carrier. The carrier may take the form
of a graphite tray with separate compartments for each of the
plurality of wafers. The wafers remain on the carrier throughout
the processing steps. For example, when a chemical vapor deposition
(CVD) step is carried out on the wafer, the carrier is present in
the CVD chamber with the wafers.
[0004] While using a carrier in this manner has the advantage of
being able to transfer many wafers between processing steps, it
also has many disadvantages. For example, in order to process many
wafers, large carriers are needed. Large carriers are expensive to
manufacture, are more difficult to maneuver with a robot, and may
damage the robot due to their weight. Further, because some
processing steps involve heating the wafers, a great amount of heat
energy is transferred to the large carriers. This thermal energy
may dissipate in portions of the process where heat is not
desirable and may damage equipment. Further, the current carriers
are made of graphite which is fragile and prone to breaking.
Breaking of carriers is not only costly due to replacement cost,
which may be around $20K, but also because it increases production
costs due to downtime and cleaning of equipment.
[0005] Because solar panel installations require very little post
installation maintenance, the viability of these projects often
turns on the projected rate of return derived from comparing the
fixed value of the energy generated over the lifetime of the system
versus the upfront costs of fabrication, and installation. In
multi-megawatt projects, where power may be sold to the offtaker
for less than $50 per megawatt hour, cost reductions of pennies per
watt can be the difference between a project being viable or too
expensive. Therefore, engineers are always seeking innovations to
lower the cost of fabrication of solar cells without sacrificing
speed of manufacture or efficiency of the solar cells.
[0006] Accordingly, there is a need for a low cost high efficiency
way of transferring wafers during the fabrication of solar
cells.
SUMMARY
[0007] This disclosure describes various embodiments that relate to
methods and apparatuses for transferring wafers between processing
steps in the fabrication of solar cells. The wafers may be
processed using a cluster tool including a load-lock, a plurality
of processing modules, and a central robot to transfer wafers
between the plurality of modules, including the load-lock. Each
module may include a pedestal including wafer recesses to support
the wafers, and puck recesses for supporting ferromagnetic pucks
below the wafers. The central robot includes electromagnets for
attracting the ferromagnetic pucks toward the electro magnets in
order to clamp the wafers between the ferromagnetic pucks and the
electromagnets. These and other embodiments are shown and discussed
in greater detail in the figures and corresponding detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The disclosure will be readily understood by the following
detailed description in conjunction with the accompanying drawings,
wherein like reference numerals designate like structural elements,
and in which:
[0009] FIG. 1A shows a puck according to various embodiments.
[0010] FIG. 1B shows a cross section of a puck according to various
embodiments.
[0011] FIGS. 2A and 2B show a pedestal according to various
embodiments.
[0012] FIG. 2C shows a cross-section of a portion of a pedestal
according to various embodiments.
[0013] FIG. 3A shows a robotic arm array according to various
embodiments.
[0014] FIG. 3B shows a portion of robotic arm array according to
various embodiments.
[0015] FIG. 3C shows a portion of robotic arm array according to
various embodiments.
[0016] FIGS. 4A-4E show steps of a process for lifting a wafer from
a pedestal according to various embodiments.
[0017] FIGS. 5A-5R show steps of processes for transferring sets of
wafers to different modules of a cluster tool according to various
embodiments.
DETAILED DESCRIPTION
[0018] Throughout this description, for the purposes of
explanation, numerous specific details are set forth in order to
provide a thorough understanding of the many aspects and
embodiments disclosed herein. It will be apparent, however, to one
skilled in the art that the many aspects and embodiments may be
practiced without some of these specific details. In other
instances, known structures and devices are shown in diagram or
schematic form to avoid obscuring the underlying principles of the
described aspects and embodiments.
[0019] FIGS. 1A and 1B show puck 102. As shown, puck 102 may be
cylindrical with a circular top surface 104 and a circular bottom
surface 106. Top surface 104 and bottom surface 106 may be
substantially planar and parallel. In embodiments, puck 102 may
have a diameter between, but not limited to, 0.1''-4'' and a
thickness between, but not limited to, 0.02''-0.25''. The diameter
of puck 102 may be based on the size and/or weight of a wafer that
puck 102 will be used to transfer, as will be discussed below.
[0020] In embodiments, the top and bottom surfaces of pucks may
have a shape other than circular, for example square, rectangular,
or any other polygon or generally round shape In embodiments, the
puck may be symmetrical with the top side and bottom side being
identical allowing for the puck to be used to transfer a wafer in
orientations with either side facing the wafer. In embodiments, the
perimeter of the top and/or bottom side may be rounded. A rounded
perimeter is beneficial in preventing a sharp edge from contacting
and damaging a wafer during transfer, as will be discussed
below.
[0021] Puck 102 may have ferromagnetic properties. In embodiments,
puck 102 includes a ferromagnetic core 108 and non-reactive
cladding 110. Ferromagnetic core may include iron, cobalt, nickel,
or any other ferromagnetic material or alloy thereof. Non-reactive
cladding 110 may be made of a material that is not reactive to the
solar cell fabrication processes which puck 102 will be present in.
Further, in embodiments, the outside surfaces of puck 102 are made
of a material that is non-marring to a wafer during processes of
fabricating a solar cell, for example chemical vapor deposition
(CVD). For example, non-reactive cladding may be comprised of
aluminum. In embodiments, non-reactive cladding 110 is comprised of
the same material as the pedestals of the chambers of processing
modules. Further in embodiments, puck 102 is configured to match
the RF characteristics of the pedestal. In embodiments, core 108
may have a thickness that is the thickness of puck 102 minus two
time the thickness of cladding 110, and cladding 110 may be from,
but not limited to 0''-0.05'' thick. In embodiments, puck may be
made of a single metal or alloy which is both ferromagnetic and
non-reactive.
[0022] In embodiments, it is beneficial for puck 102 to be
lightweight so that a robot transferring a plurality wafers and
pucks, as will be discussed below, is not damaged due to excessive
loading. However, it is also desirable for pucks to have a
sufficient mass of material with ferromagnetic properties to be
able to be attracted to an electromagnet with sufficient force to
support a wafer, as will be discussed below. For example, in
embodiments, single robotic arm electromagnets may be configured to
be able to lift the weight of the wafer, for example .about.0.01 kg
for a 6''.times.6'' silicon wafers, plus the weight of puck 102,
pucks 102 and may have a mass of between, but not limited to, 0.005
kg-0.1 kg.
[0023] In embodiments, pucks, as disclosed above, are configured to
be supported in pedestals. FIGS. 2A-2C show various views of
pedestal 212 that may be used with pucks 102. Pedestals 212 may be
present in various processing modules used in the fabrication of
solar cells. As shown, pedestals 212 may include a plurality of
wafer recesses 214 configured to receive and support wafers. During
processing, wafers are supporting by pedestal 212 so that one side
of the wafer is exposed to processing, for example CVD. Each wafer
recess 214 may include puck recess 216 substantially in the center
of wafer recess 214. In embodiments, puck recess 216 may be located
anywhere in wafer recess 214. Further, in embodiments, two or more
puck recesses may be present in a wafer recess.
[0024] As shown, wafer recess 214 may include a support surface 218
for supporting a wafer. Support surface 218 may be recessed below
top surface 220 of pedestal 212 to a depth corresponding to the
thickness of a wafer. For example, depth may be from 0.01''-025''.
In embodiments, the top of a wafer may be supported above, flush
with or below top surface 220.
[0025] As shown in cross-section of FIG. 2C, puck recess 216 is
recessed below support surface 218. The depth of puck recess 216
may correspond to the thickness of puck 102. In embodiments, puck
recess 216 may have a depth exactly corresponding to the thickness
of puck 102 so that a wafer supported on support surface 218 will
be contacting top surface of puck 102. As shown in FIG. 2B, puck
recess 216 may be cylindrical corresponding to cylindrical pucks.
Cylindrical pucks and puck recesses are beneficial because pucks
may be received in any axially orientation. This is advantageous
compared to other shapes, for example squares which will only be
receivable within a puck recess with perfect or near perfect
alignment. In embodiments, puck recess 216 may have any shape
corresponding to the shape of a puck. A puck recess may be
dimensioned larger in diameter than a corresponding puck in order
to allow the puck to be easily placed into and removed from the
puck recess.
[0026] In embodiments, pedestal may not include wafer recesses. A
plurality of wafers may be supported on a common support surface
including one or more wafer recesses for each wafer.
[0027] In embodiments, pedestals for use in chambers of processing
modules, such as CVD chambers, may be made of materials compatible
with the process performed in the chamber. For example, pedestals
may be made of alloys of aluminum, grades of aluminum oxide, and/or
grades of aluminum nitride. Further, because ferromagnetic pucks
may be used to transfer wafers, as will be discussed in greater
detail below, in embodiments, pedestals are made from a
non-ferromagnetic material so that magnets attracting pucks are not
attracted to the pedestal.
[0028] In embodiments, to ensure that the bottom side of a wafer
and a puck do not react during certain processes performed on the
top side of the wafer, the pedestal may include a trickle purge
line directed into the wafer recess and/or the puck recess. The
trickle purge line may release an inert gas into the recesses in
order have a constant flow of gas out of the recesses in order to
prevent processing gases and materials from entering the recesses
and reacting with the puck or bottom side of the wafer. Further,
the trickle purge line may be used to actively regulate the
temperature of the wafer during processing of the wafer.
[0029] As discussed, pedestals may be located within a chamber of a
processing module, such as CVD module. In embodiments, pedestals
may be present in other modules used during the fabrication process
for solar cells. For example, pedestals may be present in load-lock
modules used for loading, and unloading, wafers into, and out of, a
cluster tool. In embodiments, pedestals in non-processing modules
may have different properties than pedestals in processing modules.
For example, pedestals not used in heating applications may be made
of materials less suitable for high heat. Further for example, in
embodiments, pedestals used in load-lock modules may be portable
and configured to be loaded into the load-lock module by a robot or
manually. For example, a pedestal may be in the form of a carrier
tray. A carrier tray pedestal may be loaded with a plurality of
wafers and pucks in a staging area and then transported to the
load-lock module of a cluster tool.
[0030] As shown in FIGS. 2A and 2B, pedestal 212 may include a
4.times.4 grid of wafer recesses 214, however in embodiments any
size grid of wafer recesses, or puck recesses, may be used. For
example, 10.times.10 or 20.times.20. The size of the grid may be
based on the maximum batch processing capability of the processing
module, the largest grid size that still meets process
non-uniformity requirements, the size and weight of the wafer, the
size of the access to the chambers of the processing modules and
the load capacity of the robot transferring the wafers and pucks.
As shown, wafer recesses are square which may correspond to square
wafers, however other shapes of wafers may be used and in
embodiments, wafer recesses have corresponding shapes to the wafers
which they support. In embodiments, wafer recesses may be arranged
in patterns other than X-Y grids, for example radial, honeycomb, or
X-Y patterns that still fit within the confines of a pedestal, such
as a circular pedestal that has square wafers
[0031] FIGS. 3A-3B show various views of embodiments of a robotic
arm array 322. Robotic arm array 322 may be attached to a central
robot of a cluster tool, as described below. The central robot may
include one or multiple arms and may be configured to move robotic
arm array 322 with multiple degrees of freedom. For example, 2 to
6, or more, degrees of freedom. As shown, robotic arm array 322 may
include a plurality of arms 324. As shown, each arm 324 may be
parallel. Each arm 324 may include a plurality of magnetic
assemblies 326. The spacing of arms 324 and the spacing of magnetic
assemblies 326 may correspond to the grid of puck recesses of a
pedestal that the robotic arm array will be used with. As shown,
robotic arm array 322 includes a 4.times.4 arrangement of magnetic
assemblies 326 corresponding to the 4.times.4 arrangement of puck
recesses 216 of pedestal 212, shown in FIG. 2A. In embodiments,
arms and magnetic assemblies may be arranged in any arrangement
corresponding to the arrangement of puck recesses in a
pedestal.
[0032] As shown, magnetic assemblies 326 may be cylindrical.
Magnetic assemblies 326 may include an electromagnet 327 actuated
by a controller. Each magnetic assembly 326 of robotic arm array
322 may be actuated individually, in groups, or all together.
Magnetic assemblies 326 may be configured to attract puck 102, as
disclosed above, in order to clamp a wafer between a contact
surface 328 of magnetic assembly 326 and puck 102. The clamped puck
may be used to transfer wafers to and from pedestals within modules
used during fabrication of solar cells. Accordingly, in
embodiments, contact surface 328 is sized substantially the same
size as top surface of puck 102. Contact surface 328 may include a
non-marring coating, for example Teflon, PEEK, Ultem, PBI, or
highly polished ceramics and metals.
[0033] As will be discussed in greater detail below, contact
surface 328 may be placed in contact with a wafer during the
process of transferring the wafer. Wafers may be extremely fragile,
therefore it is important to reduce the initial impact force of
contacting the wafer in order to avoid damaging the wafer. In
embodiments, as shown in FIG. 3C, in order to reduce the impact
force, contact surface 328 may include spring dampers 330 to allow
for magnetic assembly to dampen impact force during initial contact
with a wafer.
[0034] FIGS. 4A-4E, show steps of a process of transferring wafer
432 from pedestal 212 using magnetic assembly 326 and puck 102. The
steps of FIGS. 4A-4E show a portion of arm 324 of robotic arm array
322, and a single wafer recess of pedestal 212. In embodiments,
each of the steps may be performed simultaneously for each wafer in
a pedestal. As shown in FIG. 4A, wafer 432 is positioned within a
wafer recess of pedestal 212 and supported on the support surface.
Below wafer 432 in a puck recess of pedestal 212 is puck 102. As
shown, the puck recess of pedestal 212 and puck 102 may have the
same depth so that wafer 432 is contacting puck 102. In order to
move wafer off of pedestal 212, arm 324, of robotic arm array 322,
is positioned over wafer 432 and magnetic assembly 326 is
positioned to be aligned over puck 102, as shown in FIG. 4B. As
noted, a contact surface of a magnetic assembly may be the same
size as top surface of puck. Alignment of a puck and a magnetic
assembly may be done with machine vision, motor encoders, or other
sensing and automated alignment techniques known in the art.
[0035] As shown in FIG. 4C, once magnetic assembly 326 is aligned
over puck 102, arm 324 is lowered until contact surface makes
contact with wafer 432. As noted, magnetic assembly may include a
spring damped contact surface so that initial contact does not
damage the wafer. Once magnetic assembly 326 is in contact with
wafer 432, electromagnet of magnetic assembly 326 is turned on in
order to attract puck 102, positioned below wafer 432, toward
magnetic assembly 326. The magnetic attraction clamps wafer 432
between magnetic assembly 326 and puck 102.
[0036] As shown in FIG. 4D, once wafer 432 is clamped between
magnetic assembly 326 and puck 102 due to the magnetic attraction,
arm 324 is lifted up and away from pedestal 212 at least a distance
which causes the bottom surface of puck 102 to be above the top
surface of pedestal 212. Once clear, arm 324 may be moved away from
pedestal 212, and wafer 432 may be transferred toward another
pedestal in another module, as shown in FIG. 4E.
[0037] FIGS. 4A-4E show a wafer being transferred from a pedestal.
In order to transfer a wafer to a pedestal, the steps are
substantially performed in reverse. Specifically, a wafer clamped
between an electromagnet assembly and a puck may be positioned over
a pedestal so that the puck is aligned over a puck recess of the
pedestal. The robotic arm is lowered so that the puck is within the
puck recess and the wafer is supported on the support surface of
the pedestal. Electromagnet of magnetic assembly is then turned off
and the puck is no longer attracted to the magnetic assembly. The
puck therefore no longer clamps the wafer and is now supported by
the puck recess. The arm is raised away from the wafer and moved
away leaving the wafer and puck behind on the pedestal.
[0038] FIGS. 4A-4E relate to transferring a single wafer and puck.
However, this process may be performed simultaneously with multiple
magnetic assemblies of a robotic arm array being used to clamp and
transfer multiple wafers and pucks to and from pedestals.
[0039] As noted, the steps shown in FIGS. 4A-4E may be used to
simultaneously transport multiple wafers between pedestals in a
cluster tool during the fabrication of solar cells. FIGS. 5A-5R
show steps of transferring multiple wafers to different positons in
a cluster tool, using the pucks, pedestals, robotic arm array, and
methods discussed above.
[0040] As shown in FIG. 5A, cluster tool 534 includes central
chamber 536 including central robot 538, as discussed above,
load-lock module 540, first processing module 542, and second
processing module 544. In embodiments, cluster tool 534 may include
any number of modules of any type, for example CVD, etching,
load-lock, measuring, cooling, or heating. Each module may include
a pedestal as discussed above, not shown in FIGS. 5A-5R for clarity
purposes.
[0041] Central chamber 536 may be kept under vacuum and each module
may include a port, between central chamber 536 and module, which
is sealable to maintain the vacuum. Load-lock module 540 includes
an access door allowing for wafers to be loaded into load-lock
module from outside of cluster tool 534. In embodiments, load-lock
module may include a pedestal and pucks, as disclosed above, and
wafers may be manually placed into each wafer recess. In
embodiments, load-lock module 540 may include a loading robot used
to move wafers from a cassette to wafer recesses of a pedestal in
load-lock module 540. In embodiments, load-lock module 540 may
include a robot for placing pucks in puck recesses of a pedestal
within load-lock module. In embodiments, as noted above, pedestals
may be portable, and a pedestal carrying wafers and pucks may be
loaded into load-lock module through an access door.
[0042] To introduce wafers 546, including corresponding pucks 102,
into central chamber 536 in order to perform processing steps on
wafers 546, the access door of load-lock module 540 is closed and
the atmosphere from load-lock module 540 is evacuated, as shown in
FIG. 5A. A port between load-lock module 540 and central chamber
536 is opened and central robot 538 moves robotic arm array 322
into load-lock module 540, as shown in FIG. 5B. The steps described
in FIGS. 4A-E may be performed and wafers 546 may be clamped
between pucks and magnetic assemblies, lifted out of wafer recesses
and moved into central chamber 536 with robotic arm array 322, as
shown in FIG. 5C. Wafers 546 may then be moved to a portion of
central chamber 536 corresponding to another module, for example
first processing module 542, as shown in FIG. 5D. The port of first
processing module 542 may be opened and wafers 546 may be placed
into first processing module 542 and aligned over and placed within
wafer recesses of a pedestal, as described above and as shown in
FIG. 5E. With each puck within a puck recess and each wafer
supported on a support surface of a wafer recess, the magnets of
the magnetic assemblies are turned off and robotic arm array 322 is
raised and removed from first processing module 542 leaving wafers
546, and corresponding pucks, left within first processing module
542, as shown in FIG. 5F. The port of first processing module 542
is closed and wafers 546 within first processing module 542 may be
processed with the pucks positioned in the pedestal below wafers
546. As will be discussed below, while one set of wafers are within
a module, central robot 538 may be used with robotic arm array 322
to move other sets of wafers between pedestals in modules of
cluster tool 534.
[0043] Once processing within first processing module 542 is
complete, the processing chamber may be opened and robotic arm
array 322 may be positioned over wafers 546, as shown in FIG. 5G,
and the processes discussed relating FIGS. 4A-E may be carried out
in order to move wafers 546 and pucks into central chamber 536, as
shown in FIG. 5H. Central robot 538 may then rotate in order to
move wafers 546, and corresponding pucks, in front of another
module, for example second processing module 544 and wafers 546 may
be loaded into second processing module 544 for processing, as
shown in FIG. 5I-5K.
[0044] In embodiments, while a first set of wafers are within a
module, for example being processed in a processing module, central
robot 538 may be used to transfer a second set of wafers between
modules. For example, while wafers 546 are being processed in
second processing module 544 another set of wafers 548 may be
placed in load-lock module 540, as shown in FIG. 5L. The steps
shown in FIGS. 5A-F may be repeated in order to load second set of
wafers 548 into first processing module 542. As shown in FIG. 5M,
while second set of wafers 548 is within first processing module
542, wafers 546 in second processing module 544 may transported out
of second processing module 544 to another module, for example
load-lock module 540, as shown in FIGS. 5M-5R. In embodiments,
wafers may be transferred from any module to any other available
module in the cluster tool in order to perform the processing
needed to fabricate solar cells.
[0045] While the examples described above relate to two sets of
wafers being transferred between three modules, in embodiments,
central robot may be used to move any number of sets of wafers
between any number of modules. In embodiments, at least one
pedestal must be empty in order to have a location to transport
wafers, from another pedestal, to the next pedestal.
[0046] While the technology disclosed is particularly advantageous
for use in vacuum environments, where other gripper technologies
may not be used, for example Bernoulli grippers, the technology may
be used in non-vacuum environments. Further, the methods and
apparatuses described herein may be used in any process of
transferring wafers, and similar shaped workpieces, and is not
limited to cluster tools. For example, in embodiments, in-line
fabrication equipment may include a gantry like device including a
magnetic assembly to move a wafer in a first pedestal of a first
in-line module to a second pedestal of a second in-line module. In
embodiments, multiple pucks and/or magnetic assemblies may be used
to move a single wafer. In embodiments, wafers may be flipped over
and placed in a pedestal so that the opposite side of the wafer
contacts the puck during transfer between modules.
[0047] The above techniques are further beneficial because
contamination of pucks may be avoided because pucks are covered
during processing. Therefore, the above methods result in high
throughput by allowing wafers to be transferred between different
types of CVD chambers, e.g. N-type and P-type, without having to
change pucks due to cross-contamination. This is advantageous over
previous methods wherein wafers would have to be moved to a
different carrier in order to be processed in a different type of
CVD chamber.
[0048] Further, the above methods and apparatuses are advantageous
because they lead to reduced weight, allowing for faster more agile
robots to be used compared to technologies which use heavy
carriers, as discussed above. Further, due to the small size of
pucks, problems associated with heat dissipation of carriers are
reduced or eliminated.
[0049] The examples discussed have related to fabrication of solar
cells, however, the technology may be used during the fabrication
of any device which uses wafers, or similar workpieces. For
example, the technology may be used in the manufacture of
integrated circuit, displays, processors, chips, or any type of
solid-state electronic device.
[0050] The various aspects, embodiments, implementations or
features of the described embodiments can be used separately or in
any combination. The foregoing description, for purposes of
explanation, used specific nomenclature to provide a thorough
understanding of the described embodiments. However, it will be
apparent to one skilled in the art that the specific details are
not required in order to practice the described embodiments. Thus,
the foregoing descriptions of specific embodiments are presented
for purposes of illustration and description. They are not intended
to be exhaustive or to limit the described embodiments to the
precise forms disclosed. It will be apparent to one of ordinary
skill in the art that many modifications and variations are
possible in view of the above teachings.
[0051] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the technology (especially
in the context of the following claims) are to be construed to
cover both the singular and the plural, unless otherwise indicated
herein or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. The term "connected" is to be construed as
partly or wholly contained within, attached to, or joined together,
even if there is something intervening. Recitation of ranges of
values herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range, or gradients thereof, unless otherwise indicated herein, and
each separate value is incorporated into the specification as if it
were individually recited herein. All methods described herein can
be performed in any suitable order unless otherwise indicated
herein or otherwise clearly contradicted by context. The use of any
and all examples, or exemplary language (e.g., "such as") provided
herein, is intended merely to better illuminate embodiments of the
technology and does not pose a limitation on the scope of the
technology unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed
element as essential to the practice of the technology.
[0052] Preferred embodiments of are described herein, including the
best mode known to the inventors for carrying out the technology.
The technology is susceptible to various modifications and
alternative constructions, and certain shown exemplary embodiments
thereof are shown in the drawings and have been described above in
detail. Variations of those preferred embodiments, within the
spirit of the present technology, will be apparent to those of
ordinary skill in the art upon reading the foregoing description.
The inventors expect skilled artisans to employ such variations as
appropriate, and the inventors intend for the technology to be
practiced otherwise than as specifically described herein.
Accordingly, it should be understood that there is no intention to
limit the technology to the specific form or forms disclosed, but
on the contrary, this technology includes all modifications and
equivalents of the subject matter recited in the claims appended
hereto as permitted by applicable law. Moreover, any combination of
the above-described elements in all possible variations thereof is
encompassed by the technology unless otherwise indicated herein or
otherwise clearly contradicted by context.
* * * * *