U.S. patent application number 16/868940 was filed with the patent office on 2020-08-20 for dual power feed rotary sputtering cathode.
This patent application is currently assigned to Buhler AG. The applicant listed for this patent is Buhler AG. Invention is credited to Daniel Theodore Crowley, Patrick Lawrence Morse.
Application Number | 20200266038 16/868940 |
Document ID | 20200266038 / US20200266038 |
Family ID | 1000004807212 |
Filed Date | 2020-08-20 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200266038 |
Kind Code |
A1 |
Crowley; Daniel Theodore ;
et al. |
August 20, 2020 |
DUAL POWER FEED ROTARY SPUTTERING CATHODE
Abstract
A rotary sputtering cathode assembly is provided that comprises
a rotatable target cylinder having a first end and an opposing
second end. A first power transfer apparatus is configured to carry
radio frequency power to the first end of the target cylinder, and
a second power transfer apparatus is configured to carry radio
frequency power to the second end of the target cylinder. Radio
frequency power signals are simultaneously delivered to both of the
first and second ends of the target cylinder during a sputtering
operation.
Inventors: |
Crowley; Daniel Theodore;
(Owatonna, MN) ; Morse; Patrick Lawrence; (Tucson,
AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Buhler AG |
Uzwil |
|
CH |
|
|
Assignee: |
Buhler AG
Uzwil
CH
|
Family ID: |
1000004807212 |
Appl. No.: |
16/868940 |
Filed: |
May 7, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15507207 |
Feb 27, 2017 |
10699885 |
|
|
PCT/US2015/047452 |
Aug 28, 2015 |
|
|
|
16868940 |
|
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|
62043711 |
Aug 29, 2014 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01J 37/3464 20130101;
H01J 37/3444 20130101; H01J 37/3435 20130101; H01J 37/342 20130101;
H01J 37/3423 20130101; H01J 37/3417 20130101 |
International
Class: |
H01J 37/34 20060101
H01J037/34 |
Claims
1. A rotary sputtering cathode assembly, comprising: a rotatable
target cylinder having a first end and an opposing second end; a
first end-block connected to the first end of the rotatable target
cylinder, wherein the first end block includes a first set of
rotary water seals configured to provide separation between water
and atmosphere, and a first set of rotary vacuum seals configured
to provide separation between vacuum and atmosphere; a first power
transfer apparatus operatively coupled to the first end-block, the
first power transfer apparatus including a first power supply bus
and a first static conductive element coupled to the first power
supply bus, wherein the first static conductive element is in
contact with a first rotary electrical contact connected to the
rotatable target cylinder; a second end-block coupled to the second
end of the rotatable target cylinder, wherein the second end block
includes a second set of rotary water seals configured to provide
separation between water and atmosphere, a second set of rotary
vacuum seals configured to provide separation between vacuum and
atmosphere; a second power transfer apparatus operatively coupled
to the second end-block, the second power transfer apparatus
including a second power supply bus and a second static conductive
element coupled to the second power supply bus, wherein the second
static conductive element is in contact with a second rotary
electrical contact connected to the rotatable target cylinder; and
a radio frequency (RF) power supply operatively coupled to the
first and second power supply busses, wherein an output of the RF
power supply is connected to an output conductor; wherein the first
and second power supply busses are respectively coupled to first
and second input conductors, which are each coupled to the output
conductor by a power splitter; wherein RF power signals from the RF
power supply are configured to be delivered from the output
conductor to the first and second power supply busses, to the first
and second static conductive elements, to the first and second
rotary electrical contacts, and to both of the first and second
ends of the rotatable target cylinder during a sputtering
operation.
2. The rotary sputtering cathode assembly of claim 1, wherein the
first power transfer apparatus and the second power transfer
apparatus are located in cooling water of the rotatable target
cylinder.
3. The rotary sputtering cathode assembly of claim 1, wherein the
first end-block is at cathode potential.
4. The rotary sputtering cathode assembly of claim 1, wherein the
rotatable target cylinder includes a target sputtering material
comprising a transparent conductive oxide.
5. The rotary sputtering cathode assembly of claim 4, wherein the
transparent conductive oxide comprises indium tin oxide.
6. The rotary sputtering cathode assembly of claim 1, wherein the
first end block further includes a first set of bearings configured
to support the rotatable target cylinder while allowing rotation of
the rotatable target cylinder relative to the first end-block.
7. The rotary sputtering cathode assembly of claim 6, wherein the
second end block further includes a second set of bearings
configured to support the rotatable target cylinder while allowing
rotation of the rotatable target cylinder relative to the second
end-block.
8. The rotary sputtering cathode assembly of claim 1, wherein the
first power transfer apparatus and the second power transfer
apparatus provide substantially equal conductance paths from the RF
power supply to each end of the rotatable target cylinder.
9. The rotary sputtering cathode assembly of claim 1, wherein the
first and second input conductors are of substantially equal
length.
10. The rotary sputtering cathode assembly of claim 1, wherein the
first and second input conductors respectively terminate at the
first and second power supply busses.
11. The rotary sputtering cathode assembly of claim 1, wherein the
RF power supply is operatively coupled to the first and second
power supply busses without a direct current (DC) power supply.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 15/507,207, filed Feb. 27, 2017, which is a U.S. National Stage
Application of PCT Application Serial No. PCT/US2015/047452, filed
Aug. 28, 2015, which claims benefit of U.S. Provisional Application
No. 62/043,711, filed on Aug. 29, 2014, the contents of the
applications of which are incorporated by reference.
BACKGROUND
[0002] Magnetron sputtering of rotating targets is well known and
is used extensively for producing a wide variety of thin films on a
wide variety of substrates. In the most basic form of
rotating-target magnetron sputtering, the material to be sputtered
from the target is either formed in the shape of a tube or is
adhered to the outer surface of a support tube made of a rigid
material. A magnetron assembly is disposed within the target and
supplies a magnetic field, which permeates the target such that
there is adequate magnetic flux at the outer surface of the target.
The magnetic field is designed in a way such that it retains
electrons emitted from the target so as to increase the probability
that the electrons will have ionizing collisions with a working
gas, hence enhancing the efficiency of the sputtering process.
[0003] A common class of materials deposited by magnetron
sputtering is transparent conductive oxides (TCOs). The most
commonly used TCO is indium tin oxide (ITO). ITO can be sputtered
reactively, wherein a metal target is sputtered in an oxidizing
atmosphere. However, sputtering ITO from a ceramic target is
frequently preferred because its process is much easier to control.
This results in more consistent high-quality films, compared with
reactive sputtering. Planar targets have historically been
preferred for ITO sputtering due to the lower fabrication costs
compared to rotary ceramic targets.
[0004] In recent years, there has been a trend away from planar ITO
target and towards rotary targets. This trend is a result of
improved fabrication techniques that lower the cost of rotary
ceramic targets, improved magnetron designs that increase the
efficiency of material use, and the rotary cathode's superior
operating performance, which helps satisfy increasing market demand
for high quality films. Additionally, rotary targets hold a larger
useable quantity of the sputtering material. This allows for
reduced system maintenance requirements and, hence, better machine
efficiency.
[0005] A sputtering method involving simultaneous application of
direct current (DC) (or pulsed DC) power and radio frequency (RF)
power has recently been applied to ITO targets. It has been
demonstrated that improvement in the ITO film qualities resulted
from the superposition of the two power sources using a planar
target. The frequency of the power source used was 13.56 MHz, which
is the most common frequency used for RF power in sputtering
operations.
[0006] In another approach to applying RF power to a rotary
cathode, RF energy is imparted into a target by transmitting an RF
power signal via an antenna located within the rotating target.
Here, the antenna is static and thus does not require a power
transfer apparatus to move the power from static to rotating
elements. This approach also disallows the superposition of DC
power onto the RF driven target.
[0007] Recently, it has been shown that the application of RF power
to a rotary cathode results in an unacceptable non-uniformity of
the deposited film thickness. The non-uniformity is thought to be
due to power (or voltage) attenuation, along the length of the
cathode, resulting from the reactive impedance of the
high-frequency of the applied voltage.
[0008] Accordingly, there remains a need for the capability of the
application of RF power to rotary sputtering cathodes that
addresses the issue of non-uniformity of deposited films.
SUMMARY
[0009] A rotary sputtering cathode assembly is provided that
comprises a rotatable target cylinder having a first end and an
opposing second end. A first power transfer apparatus is configured
to carry radio frequency power to the first end of the target
cylinder, and a second power transfer apparatus is configured to
carry radio frequency power to the second end of the target
cylinder. Radio frequency power signals are simultaneously
delivered to both of the first and second ends of the target
cylinder during a sputtering operation.
DRAWINGS
[0010] FIG. 1 is a perspective view of a rotary sputtering cathode
assembly according to one embodiment;
[0011] FIG. 2 is a partial cross-sectional side view of the rotary
sputtering cathode assembly of FIG. 1;
[0012] FIG. 3 is an enlarged cross-sectional side view of one end
of the rotary sputtering cathode assembly taken along line 3-3 of
FIG. 2;
[0013] FIG. 4 is a perspective view of a rotary sputtering cathode
assembly according to another embodiment;
[0014] FIG. 5 is a partial cross-sectional side view of the rotary
sputtering cathode assembly of FIG. 4;
[0015] FIG. 6 is an enlarged cross-sectional side view of one end
of the rotary sputtering cathode assembly taken along line 6-6 of
FIG. 5; and
[0016] FIG. 7 is a schematic diagram of a power circuit according
to one embodiment, which provides substantially equal conductance
paths for a rotary sputtering cathode assembly.
DETAILED DESCRIPTION
[0017] An apparatus and method for the application of radio
frequency (RF) power to rotary sputtering cathodes is provided. In
particular, equipment and methodology are provided for applying RF
power, which results in symmetric film deposition.
[0018] A rotary sputtering cathode generally comprises one or more
end-blocks and a target assembly. The end-blocks are the mechanical
apparatus that support the target assembly and provide the
interface between the target and supporting utilities, such as
power, rotation, and cooling water. The target assembly generally
includes a target cylinder, with an outer surface composed of a
material to be sputtered, and a magnet element within the target
cylinder. The magnet element provides a magnetic field that
permeates the target cylinder such that there is a useful magnetic
field at the outer surface of the target cylinder.
[0019] There are two basic types of rotary cathodes, including a
dual end-block type rotary cathode and a single end-block type
rotary cathode. Both types of rotary cathodes have a common set of
components that include, but are not necessarily limited to,
bearings that support the target assembly while allowing rotation
relative to the end-block(s); rotary seals that provide separation
between vacuum and water, or between vacuum and atmosphere; a
rotation drive apparatus that imparts rotating motion to the target
assembly; cooling water delivery apparatus; and a rotary power
transfer apparatus or interface that transmits power from a static
element to the rotating target assembly.
[0020] In the dual end-block rotary cathode, the apparatus for
rotation, power transfer, and water delivery (collectively, the
utility apparatus) are divided between the two ends. Additionally,
both end-blocks have at least one of the bearings and rotary seals.
The single end-block cathode has all of the utility apparatus, as
well as the rotary seals and the bearings, in a single mechanical
apparatus at one end of the target assembly. Optionally, the single
end-block cathode may be augmented with a target support at the
distal end, which may be construed as a rotary bearing. The distal
end of the single end-block cathode will generally not have any
other components required for operation.
[0021] Conventional rotary cathodes provide apparatus for rotation,
water delivery, and power transfer at only one end or the other end
of the target assembly. In some cases, such as in the use of RF
power, applying power to only one end of the cathode results in
unacceptable non-uniformity of the sputtering/deposition process.
For example, while the application of RF power to a rotary indium
tin oxide (ITO) target significantly improves the quality of the
deposited ITO film, it is still necessary to overcome the
non-uniformity issue in order to make the technique feasible for
industrial use.
[0022] The present approach resolves this issue by supplying power
signals to both ends of the target cylinder in the cathode
assembly. This achieves acceptable deposition uniformity while
operating the cathode assembly with RF power. In addition, the
present system can provide symmetric and even power application to
both ends of the sputtering target cylinder, resulting in improved
uniformity.
[0023] In one embodiment, a second power transfer apparatus is
implemented at the opposite end of the target cylinder from a first
power transfer apparatus, allowing for a two-ended power feed to
both ends of the target cylinder. This results in a symmetric film
deposition and uniformity during a sputtering operation.
[0024] In one implementation, the two-ended power feed embodiment
can be achieved by using two end-blocks for a single end-block type
rotary cathode, arranged with one end-block at each end of the
target cylinder. The power is supplied to the target cylinder from
the power transfer apparatus in each of the end-blocks. An example
of a suitable end-block for this arrangement is the MC style
end-block, produced by Sputtering Components, Inc. (SCI), which are
typically used in single-ended rotary cathodes. This arrangement
results in redundancy of the water delivery and rotation apparatus.
While only one rotation apparatus is needed, it is desirable to
allow the flow of cooling water through the second end-block in
order to cool and lubricate the power transfer apparatus within.
This can readily be achieved by connecting the water outlet to the
inlet on the second end-block.
[0025] An alternate arrangement for achieving the two-ended power
feed is to use one end-block from a single end-block type cathode
in conjunction with a power delivering end-block from a two
end-block type cathode. An example of a suitable arrangement
comprises SCI's MC cathode, at one end, and the power end-block
from SCI's TC cathode at the other end. The power end-block of the
TC cathode also has the desired water delivery apparatus, thereby
allowing cooling and lubricating of the power transfer apparatus.
As the power end-block of the TC cathode does not have a rotation
apparatus, there is no redundancy of the rotation drive in this
arrangement.
[0026] Additional alternate suitable arrangements may be provided
through custom designs that provide power transfer feeds to both
ends of the target cylinder. In most cases, the second power
transfer apparatus may require water flow for cooling and
lubrication. A water requirement also implies the need for rotary
seals. In other embodiments, a power transfer apparatus may not
require the presence of water. Alternately, a specially designed
secondary end can be implemented to provide power delivery to the
outboard end of the cathode.
[0027] In one implementation, RF power may be applied to the two
ends of any suitable cathode arrangement by the use of two separate
power supplies. In this arrangement, the power supplies can be
synchronized such that the applied voltages are substantially in
phase in order to help ensure that there is minimal destructive
interference of the two voltage waves. Synchronization also
prevents undesired feedback from one power supply to the other.
[0028] In another implementation, RF power delivery is provided by
splitting the output from a single power source. For example, a bus
bar can be provided between the two end-blocks, with a power tap
substantially at the center point of the bus bar such that the
conduction path to each end of the target cylinder is essentially
equal. Although this arrangement may generally be adequate, it is
possible that there may be significant differences in the
conduction paths to the two ends of the target cylinder. For
example, this may occur if there is a variation in the two
end-blocks, such as in the configuration that uses a combination of
MC and TC cathode components. It is possible that other, less
predictable, outside influences can also affect the conductance to
the cathode. To counteract any potential asymmetry of power
delivery, an optional power splitting circuit can be added between
the RF power source and the target cylinder. This circuit can be
designed such that it forces an equal amount of current to each end
of the target cylinder, and can tune the power directed to each end
to affect uniformity of target material deposition.
[0029] RF power sources generally include a generator that provides
power at the prescribed frequency, and a load match circuit that
conditions the power signal such that the output impedance of the
source matches the input impedance of the sputtering process, thus
ensuring optimal power delivery efficiency to the process. In one
embodiment, superposition of RF and DC power can be applied to a
rotary ITO sputtering target, which produces a superior film
compared to DC sputtering alone. The present approach can use any
frequency for the power signal for which a benefit can be
realized.
[0030] In another embodiment, a power transfer interface can be
located in the cooling water of the target cylinder. In a further
embodiment, the main end-block body can be at cathode
potential.
[0031] Further details of various embodiments are described
hereafter with reference to the drawings.
[0032] FIGS. 1-3 illustrate a rotary cathode assembly 100 according
to one embodiment. The rotary cathode assembly 100 includes a pair
of end-blocks 102 and 104, which are located on opposing ends of a
sputtering target cylinder 110. The target cylinder 110 is
rotatable around a stationary magnet bar assembly, which is
suspended inside of target cylinder 110 and coupled to a coolant
water tube.
[0033] In one embodiment, target cylinder 110 has a target material
on an outer surface thereof. Alternatively, target cylinder 110 can
be composed of the target material. Exemplary target materials for
target cylinder 110 include transparent conductive oxides (TCOs),
such as indium tin oxide (ITO).
[0034] The end-block 102 includes a power bus 118 that is
configured for connection to a power supply. A set of water tube
connectors 120 is configured to supply water into and out of
end-block 102, which communicates with the water tube as part of
the cooling water delivery apparatus for target cylinder 110.
[0035] As shown in FIGS. 2 and 3, a set of rotary water seals 122
located in end-block 102 provides separation between water and
atmosphere. A set of rotary vacuum seals 124 located in end-block
102 provides separation between vacuum and atmosphere. A set of
bearings 126 in end-block 102 supports target cylinder 110 while
allowing rotation of target cylinder 110 relative to end-block 102.
The end-block 102 also houses an electrical stator 128 in
electrical communication with power bus 118. The stator 128
operatively communicates with an electrical rotor 130 coupled to
target cylinder 110 such that power is transmitted from stator 128
to rotor 130 to provide power to target cylinder 110.
[0036] Similarly, end-block 104 includes a power bus 132 that is
configured for connection to a power supply, and a pair of tube
water connectors 134 configured to supply water into and out of
end-block 104, which communicates with the water tube in target
cylinder 110. As shown in FIG. 2, a set of rotary water seals 136
located in end-block 104 provides separation between vacuum, water,
and atmosphere. A set of rotary vacuum seals 138 located in
end-block 104 provide separation between vacuum and atmosphere. A
set of bearings 140 in end-block 104 also support target cylinder
110 while allowing rotation of target cylinder 110 relative to
end-block 104. In addition, a static electrical contact 142 in
end-block 102 is in electrical communication with power bus 132.
The static electrical contact 142 communicates with a rotary
electrical contact 144 coupled to target cylinder 110 such that
power is transmitted to target cylinder 110.
[0037] A rotation drive motor 148 is operatively coupled to
end-block 102 to impart rotating motion to target cylinder 110. The
drive motor 148 is typically located outside of a vacuum chamber
that houses target cylinder 110 and end-blocks 102, 104. The drive
motor 148 engages with a rotation drive belt 152 that extends into
end-block 102 as part of the rotation drive apparatus for target
cylinder 110. As depicted in FIGS. 2 and 3 end-block 102 houses a
rotary drive shaft 160 that is operatively coupled to target
cylinder 110. A drive gear 162 is connected to drive belt 152 and
is hobbed into drive shaft 160.
[0038] FIGS. 4-6 illustrate a rotary cathode assembly 200 according
to another embodiment. The rotary cathode assembly 200 includes a
first end-block 202 and a second end-block 204 located on opposing
ends of a sputtering target cylinder 210. The target cylinder 210
is rotatable around a stationary magnet bar assembly, which is
suspended inside of target cylinder 210 and coupled to a coolant
water tube.
[0039] The end-block 202 includes similar components as end-block
102 described previously. Accordingly, end-block 202 includes a
power bus 218 that is configured for connection to a power supply.
A set of water tube connectors 220 is configured to supply water
into and out of end-block 202, which communicates with the water
tube as part of the cooling water delivery apparatus for target
cylinder 210.
[0040] As depicted in FIG. 5, a set of rotary water seals 222
located in end-block 202 provides separation between water and
atmosphere. A set of rotary vacuum seals 224 located in end-block
202 provides separation between vacuum and atmosphere. A set of
bearings 226 in end-block 202 supports target cylinder 210 while
allowing rotation of target cylinder 210 relative to end-block
202.
[0041] In addition, a static contact plate 228 in end-block 202 is
in electrical communication with power bus 218. The static contact
plate 228 electrically communicates with a rotary contact plate 230
on a target flange of target cylinder 210 such that power is
transmitted to target cylinder 210.
[0042] The end-block 204 includes a power bus 232 that is
configured for connection to a power supply. A pair of water
connectors 234 is configured to supply water into and out of
end-block 204, which communicates with the water tube in target
cylinder 210. As shown in FIGS. 5 and 6, a set of water seals 236
located in end-block 204 provides separation between vacuum and
water. A bearing 240 in end-block 204 also supports target cylinder
210 while allowing rotation of target cylinder 210.
[0043] In addition, a static contact plate 242 in end-block 204 is
in electrical communication with power bus 232, as depicted in FIG.
6. The static contact plate 242 electrically communicates with a
rotary contact plate 244 on a target flange of target cylinder 210
such that power is transmitted to target cylinder 210.
[0044] As illustrated in FIGS. 4 and 5, a rotation drive motor 248
is operatively coupled to end-block 202 to impart rotating motion
to target cylinder 210. The drive motor 248 engages with a rotation
drive belt 252 that extends into end-block 202 as part of the
rotation drive apparatus for target cylinder 210. As depicted in
FIG. 5, end-block 202 houses a rotary drive shaft 260 that is
operatively coupled to target cylinder 210. A drive gear 262 is
connected to drive belt 252 and is hobbed into drive shaft 260.
[0045] FIG. 7 illustrates a power circuit 300 according to one
embodiment, which provides substantially equal conductance paths
for a rotary sputtering cathode assembly 302. The rotary sputtering
cathode assembly 302 includes a rotatable target cylinder 304
having a first end 306 and an opposing second end 308. A first
end-block 310 is coupled to first end 306, and a second end-block
312 is coupled to second end 308. The first end-block 310 houses a
first power transfer apparatus configured to carry RF power to
first end 306, and second end-block 312 houses a second power
transfer apparatus configured to carry RF power to second end 308.
The first end-block 310 is coupled to a first power supply bus 314,
and second end-block 312 is coupled to a second power supply bus
316.
[0046] As shown in FIG. 7, an RF power supply 320 and a DC power
supply 322 are coupled to a common ground connection 324. The
positive lead on DC power supply 322 may also optionally be
connected to a separate floating anode inside a chamber of cathode
assembly 302. The negative terminal of DC power supply 322 is
connected to a low pass filter 326, which prevents the RF signal
from entering DC power supply 322. The output terminal of RF power
supply 320 is connected to a conductor 328 that is joined by the
output from low pass filter 326. The conductor 328 is split into
two separate conductors 330 and 332 of substantially equal length,
which respectively terminate at power supply busses 314 and 316.
The power circuit 300 allows target cylinder 304 to be powered from
both of ends 306 and 308 simultaneously during a sputtering
operation.
Example Embodiments
[0047] Example 1 includes a rotary sputtering cathode assembly
comprising a rotatable target cylinder having a first end and an
opposing second end; a first power transfer apparatus configured to
carry radio frequency (RF) power to the first end of the target
cylinder; and a second power transfer apparatus configured to carry
RF power to the second end of the target cylinder; wherein RF power
signals are simultaneously delivered to both of the first and
second ends of the target cylinder during a sputtering
operation.
[0048] Example 2 includes the rotary sputtering cathode assembly of
Example 1, further comprising a first end-block located at the
first end and a second end-block located at the second end, the
first and second end-blocks respectively housing the first and
second power transfer apparatus.
[0049] Example 3 includes the rotary sputtering cathode assembly of
any of Examples 1-2, wherein the first and second power transfer
apparatus each transmits power from a static element to the target
cylinder.
[0050] Example 4 includes the rotary sputtering cathode assembly of
any of Examples 1-3, wherein the first power transfer apparatus
communicates with a first RF power source connected to the first
end, and the second power transfer apparatus communicates with a
second RF power source connected to the second end.
[0051] Example 5 includes the rotary sputtering cathode assembly of
Example 4, wherein the first and second RF power sources are
synchronized.
[0052] Example 6 includes the rotary sputtering cathode assembly of
any of Examples 1-3, wherein the first power transfer apparatus and
the second power transfer apparatus both communicate with a single
RF power source.
[0053] Example 7 includes the rotary sputtering cathode assembly of
Example 6, wherein the first power transfer apparatus and the
second power transfer apparatus provide substantially equal
conductance paths from the single RF power source to each end of
the target cylinder.
[0054] Example 8 includes the rotary sputtering cathode assembly of
any of Examples 6-7, further comprising a power splitter coupled to
the single RF power source and configured to provide substantially
equal current to each end of the target cylinder.
[0055] Example 9 includes the rotary sputtering cathode assembly of
any of Examples 1-8, wherein the target cylinder includes a target
sputtering material comprising a transparent conductive oxide.
[0056] Example 10 includes the rotary sputtering cathode assembly
of Example 9, wherein the transparent conductive oxide comprises
indium tin oxide.
[0057] Example 11 includes the rotary sputtering cathode assembly
of any of Examples 1-10, wherein one or more additional power
signals are superimposed on the RF power signals.
[0058] Example 12 includes the rotary sputtering cathode assembly
of Example 11, wherein the one or more additional power signals
comprise direct current (DC) power signals.
[0059] Example 13 includes a rotary sputtering cathode assembly
comprising a rotatable target cylinder having a first end and an
opposing second end; a first end-block connected to the first end
of the target cylinder; a first power transfer apparatus
operatively coupled to the first end-block and configured to carry
radio frequency (RF) power signals to the first end of the target
cylinder, the first power transfer apparatus including a first
static conductive element in contact with a first rotary conductive
element connected to the target cylinder; a second end-block
coupled to the second end of the target cylinder; and a second
power transfer apparatus operatively coupled to the second
end-block and configured to carry RF power signals to the second
end of the target cylinder, the second power transfer apparatus
including a second static conductive element in contact with a
second rotary conductive element connected to the target cylinder;
wherein the RF power signals are simultaneously delivered to both
of the first and second ends of the target cylinder during a
sputtering operation.
[0060] Example 14 includes the rotary sputtering cathode assembly
of Example 13, wherein the first power transfer apparatus
communicates with a first RF power source connected to the first
end, and the second power transfer apparatus communicates with a
second RF power source connected to the second end.
[0061] Example 15 includes the rotary sputtering cathode assembly
of Example 14, wherein the first and second RF power sources are
synchronized.
[0062] Example 16 includes the rotary sputtering cathode assembly
of Example 13, wherein the first power transfer apparatus and the
second power transfer apparatus are both coupled with a single RF
power source.
[0063] Example 17 includes the rotary sputtering cathode assembly
of Example 16, wherein the first power transfer apparatus and the
second power transfer apparatus provide substantially equal
conductance paths from the single RF power source to each end of
the target cylinder.
[0064] Example 18 includes the rotary sputtering cathode assembly
of any of Examples 13-17, wherein the first power transfer
apparatus and the second power transfer apparatus are located in
cooling water of the target cylinder.
[0065] Example 19 includes the rotary sputtering cathode assembly
of any of Examples 13-18, wherein the first end-block is at cathode
potential.
[0066] Example 20 includes the rotary sputtering cathode assembly
of any of Examples 13-19, wherein the target cylinder includes a
target sputtering material comprising a transparent conductive
oxide.
[0067] While a number of embodiments have been described, it will
be understood that the described embodiments are to be considered
only as illustrative and not restrictive, and that various
modifications to the described embodiments may be made without
departing from the scope of the invention. The scope of the
invention is therefore indicated by the appended claims rather than
by the foregoing description. All changes that come within the
meaning and range of equivalency of the claims are to be embraced
within their scope.
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