U.S. patent application number 10/098559 was filed with the patent office on 2003-09-18 for high-power ion sputtering magnetron.
This patent application is currently assigned to Sputtering Components, Inc.. Invention is credited to Crowley, Daniel T..
Application Number | 20030173217 10/098559 |
Document ID | / |
Family ID | 28039390 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030173217 |
Kind Code |
A1 |
Crowley, Daniel T. |
September 18, 2003 |
High-power ion sputtering magnetron
Abstract
A high-power ion sputtering magnetron having a rotary cathode
comprising a conducting member disposed within the rotary cathode
being made of an electrically conductive material for conducting
electrical current from the power supply to the rotary cathode. The
ion sputtering magnetron also has an electromagnetic field shield
disposed between the conducting member and the drive shaft portion.
The field shield is made of an electromagnetic field-permeable
material such as a ferrous material for reducing damage to parts
adjacent to the rotary cathode that are susceptible to inductive
magnetic heating.
Inventors: |
Crowley, Daniel T.;
(Owatonna, MN) |
Correspondence
Address: |
MOORE, HANSEN & SUMNER
2900 WELLS FARGO CENTER
90 SOUTH SEVENTH STREET
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Sputtering Components, Inc.
|
Family ID: |
28039390 |
Appl. No.: |
10/098559 |
Filed: |
March 14, 2002 |
Current U.S.
Class: |
204/298.22 ;
204/298.09; 204/298.21 |
Current CPC
Class: |
H01J 37/3405 20130101;
H01J 37/3497 20130101; H01J 37/3411 20130101 |
Class at
Publication: |
204/298.22 ;
204/298.21; 204/298.09 |
International
Class: |
C23C 014/34 |
Claims
What is claimed is:
1. A rotary cathode device connectable to a power supply of
electrical current, said rotary cathode device comprising: a
conducting member disposed within the rotary cathode device, said
conducting member being made of an electrically conductive material
for conducting the electrical current from the power supply to the
rotary cathode device.
2. A rotary cathode device as in claim 1 wherein said conducting
member is a coolant conduit.
3. A rotary cathode device as recited in claim 1 further comprising
a drive shaft portion, said drive shaft portion includes an
interior surface and an exterior surface.
4. A rotary cathode device as recited in claim 3 wherein said drive
shaft portion is further made of an electromagnetic field-permeable
material.
5. A rotary cathode device as recited in claim 4 wherein said
electromagnetic field-permeable material is a ferrous material.
6. A rotary cathode device as recited in claim 3 further comprising
an electromagnetic field shield disposed between the conducting
member and the drive shaft portion, said electromagnetic field
shield is made of an electromagnetic field-permeable material.
7. A rotary cathode device as recited in claim 3 further comprising
an electromagnetic field shield attached to at least a portion of
the interior surface of the drive shaft portion, said
electromagnetic field shield is made of an electromagnetic
field-permeable material.
8. A rotary cathode device as recited in claim 3 further comprising
an electromagnetic field shield attached to at least a portion of
the exterior surface of the drive shaft portion, said
electromagnetic field shield is made of an electromagnetic
field-permeable material.
9. A rotary cathode device connectable to a power supply of
electrical current, said rotary cathode device comprising: a
coolant conduit disposed within the rotary cathode device made of
an electrically conductive material for connecting the electrical
current from the power supply to the rotary cathode; and a drive
shaft portion made of a ferrous material for absorbing the
electromagnetic field to reduce heat damage to parts adjacent to
the rotary cathode device that are susceptible to inductive
magnetic heating.
10. A high-power ion sputtering magnetron connectable to a power
supply of electrical current, said magnetron device comprising: a
rotary cathode disposed upon the magnetron device, said rotary
cathode comprising a conducting member disposed within the rotary
cathode, said conducting member being made of an electrically
conductive material for connecting the electrical current from the
power supply to the rotary cathode.
11. A magnetron device as recited in claim 10 wherein the
conducting member is a coolant conduit.
12. A magnetron device as recited in claim 10 wherein the rotary
cathode further comprises a drive shaft portion rotatably disposed
upon the magnetron device, and said drive shaft portion includes an
interior surface and an exterior surface.
13. A magnetron device as recited in claim 12 wherein the drive
shaft portion is further made of an electromagnetic field-permeable
material.
14. A magnetron device as recited in claim 13 wherein the
electromagnetic field-permeable material is a ferrous material.
15. A magnetron device as recited in claim 12 wherein the rotary
cathode further comprises an electromagnetic field shield disposed
between the conducting member and the drive shaft portion, said
field shield is made of an electromagnetic field-permeable
material.
16. A magnetron device as recited in claim 12 wherein the rotary
cathode further comprises an electromagnetic field shield attached
to at least a portion of the interior surface of the drive shaft
portion, the field shield is made of an electromagnetic
field-permeable material.
17. A magnetron device as recited in claim 12 wherein the rotary
cathode further comprises an electromagnetic field shield attached
to at least a portion of the exterior surface of the drive shaft
portion, and the drive shaft portion is made of an electromagnetic
field-permeable material.
18. A high-power ion sputtering magnetron connectable to an
electrical power supply, said magnetron device comprising: a rotary
cathode rotatably mounted upon the magnetron device, said rotary
cathode comprising a conducting member disposed within the rotary
cathode, said conducting member being made of an electrically
conductive material for connecting the electrical current from the
power supply to the rotary cathode; and a drive shaft portion
rotatably mounted to the magnetron device, said drive shaft portion
being made of a ferrous material for absorbing the electromagnetic
field to reduce heat damage to parts adjacent to the rotary cathode
device that are susceptible to inductive magnetic heating.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to thin film coating
deposition devices. More particularly, the present invention
relates to shielded rotary cathodes for use in high-powered ion
sputtering magnetrons.
[0002] Rotary or rotating cylindrical cathodes were developed to
overcome some of the problems associated with planar magnetrons.
Examples of the rotating cathode are further described in U.S. Pat.
Nos. 4,356,073 and 4,422,916, the entire disclosures of which are
hereby incorporated by reference. Various mounting, sealing and
driving arrangements for cylindrical cathodes are described in U.S
Pat. Nos. 4,443,318; 4,445,997; 4,466,877, the entire disclosures
of which are hereby incorporated by reference. Those patents
describe rotating cathodes mounted horizontally in a coating
chamber supported at both ends. It is often preferable to support
the rotary cathode at only one end by a cantilever mount such as
described in U.S. Pat. No. 5,200,049, the disclosure of which is
also hereby incorporated by reference.
[0003] In recent years, the sputter coating industry has moved
toward high-power sputtering. Manufacturers of such devices have
been providing higher powers to the sputtering equipment to provide
the end-user with increasing rates of coating material sputtered
from the cathodes ultimately to increase plant productivity. With
these advances have come the important problems of equipment
failure due to magnetic inductive heating of parts. Manufacturing
plant line shutdowns caused by such failure are extremely expensive
because significant downtime and repair costs are required to fix
damaged equipment. Ion sputtering magnetrons utilizing high-power
alternating current are susceptible to such damage and failure from
magnetic inductive heating of its sensitive parts.
[0004] For example, a rotary cathode used in an ion sputtering
magnetron is susceptible to seizure from a number of failure modes.
As alternating current and frequency increase, parts in the
sputtering magnetron become more susceptible to heat damage.
Rotation stoppage of the rotary cathode can be due to bearing
seizure either in the main bearings or the rotary seal bearings.
Failure can also be due to rotary seal leakage caused by
overheating. Still another failure can be insulation breakdown due
to exposure to overheated neighboring parts. Inductive heating is
greatly magnified in ferro-magnetic materials that make up most
bearings and the primary parts of the preferred rotary seal,
namely, the ferrous fluid seal. Consequently, another significant
failure point is the rotary seal which is susceptible to being
easily damaged from excessive inductive heating. Additional failure
modes with this rotary seal include seizure and atmospheric leakage
which will shut down the sputtering process and, consequently, the
manufacturing line, at great cost.
[0005] Another significant problem encountered is when the target
material of a rotary cathode sputters mostly at one end of the
target at the point where electricity from the drive shaft connects
to the target. This causes non-uniform coatings on the product that
need to be compensated for by masking or other problematic or
expensive means. Shutting down the manufacturing line to replace
those rotary cathode targets is also very costly.
[0006] Still another problem caused by high power is resistive
heating. Resistive heating of parts in the current path also limits
the power that can be applied.
[0007] Yet another problem is shorting and arcing at higher powers
and voltages due to conductive dust from the electrical brushes
that bridges insulators inside existing cathode design.
[0008] Thus, there is a need in the art for providing a
high-powered ion sputtering magnetron which is less susceptible to
heat damage caused by magnetic inductive heating to increase plant
productivity.
BRIEF SUMMARY OF THE INVENTION
[0009] Currently, it is an object of this invention to provide an
improved rotary cathode for thin film coating deposition devices,
such as ion sputtering magnetrons for shielding sensitive parts in
the sputtering magnetron from magnetic inductive heating damage to
increase plant productivity.
[0010] An advantage to the present invention is that it simplifies
design and eliminates the need for running utilities to both end
supports, thereby eliminating the need for additional power,
coolant, drive, rotary seals and all the other accompanying
air-to-vacuum seals.
[0011] Another advantage is that this design eliminates resistive
heating as the entire power train is directly water-cooled. This
allows greatly increased power on the conductors in the
cathode.
[0012] Still another advantage of the invention is that it shields
heat-sensitive parts by absorbing fluctuating magnetic fields and
blocks electrical noise.
[0013] Yet another invention advantage is that the electrical
brushes are placed inside the cathode cooling system where dust is
flushed out and cannot bridge insulators inside the cathode thereby
reducing incidents of shorting and arcing. Because these brushes
are internal to the cathode, the brushes can be distributed evenly
inside the target allowing a more uniform power distribution and
therefore providing more uniform target wear and a more uniform
coating and deposition on the product.
[0014] The rotary cathode device for an ion sputtering magnetron of
the present invention comprises a conducting member disposed within
the rotary cathode device. The conducting member is made of an
electrically conductive material for conducting electrical current
from the power supply to the rotary cathode device. The conducting
member is preferably a coolant conduit.
[0015] The rotary cathode device further comprises a drive shaft
portion which includes an interior surface and an exterior surface.
The drive shaft portion is further made of an electromagnetic
field-permeable material such as a ferrous material.
[0016] In other embodiments of the invention, the drive shaft need
not be made of any particular material, but instead, an
electromagnetic field shield is disposed between the conducting
member and the drive shaft portion with the shield being made of an
electromagnetic field-permeable material. For example, in another
preferred embodiment of the invention, the electromagnetic field
shield is attached to at least a portion of the interior surface of
the drive shaft portion or the shield is made of electromagnetic
field-permeable material.
[0017] In another preferred embodiment of the invention, the
electromagnetic field shield is attached to at least a portion of
the exterior surface of the drive shaft portion with the shield
being made of an electromagnetic field-permeable material. A rotary
cathode device, connectable to a power supply of electrical
current, comprises a coolant conduit disposed within the rotary
cathode device made of an electrically conductive material for
conducting electrical current from the power supply to the rotary
cathode. Also, a drive shaft portion is made of a ferrous material
for absorbing the electromagnetic field to reduce the heat damage
to parts adjacent to the rotary cathode device that are susceptible
to magnetic heating.
[0018] Also provided is a high-powered ion sputtering magnetron
which is connectable to a power supply of electrical current. The
magnetron device comprises a rotary cathode disposed upon the
magnetron device. The rotary cathode comprises a conducting member
disposed within the rotary cathode. The conducting member is made
of an electrically conductive material for connecting the
electrical current from the power supply to the rotary cathode.
[0019] In one preferred embodiment, a high-power ion sputtering
magnetron comprises a rotary cathode rotatably mounted upon the
magnetron device. The rotary cathode comprises a conducting member
disposed within the rotary cathode. The conducting member is made
of electrically conductive material for conducting the electrical
current from the power supply to the rotary cathode. The magnetron
device further comprises a drive shaft portion rotatably mounted to
the magnetron device. The drive shaft portion is made of a ferrous
material for absorbing the electromagnetic field to reduce heat
damage to parts adjacent to the rotary cathode device that are
susceptible to inductive magnetic heating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Other objects, common features and advantages of the present
inventions will become more fully apparent from the following
detailed description of preferred embodiment, the appended claims
and the accompanying drawings in which:
[0021] FIG. 1 is a cross-sectional view of a first preferred
embodiment of the invention showing the rotary cathode with a
magnetic field permeable shield affixed to the drive shaft interior
as installed in the high-powered ion sputtering magnetron
incorporating a cantilever-style rotary cathode;
[0022] FIG. 2 is a cross-sectional view of a first preferred
embodiment of the invention showing the rotary cathode with a
magnetic field permeable shield affixed to the drive shaft interior
as installed in the high-powered ion sputtering magnetron in the
form of a double-ended support style rotary cathode;
[0023] FIG. 3 is a side elevational, cross-sectional view of a
first preferred embodiment of the invention showing the drive shaft
with the magnetic field permeable material fixed to the interior of
the drive shaft;
[0024] FIG. 4 is a side elevational, cross-sectional view of a
second preferred embodiment of the rotary cathode invention showing
the magnetic field permeable material fixed around the exterior of
the drive shaft;
[0025] FIG. 5 is a side elevational, cross-sectional view of a
third preferred embodiment of the rotary cathode invention showing
the drive shaft itself being made of a magnetic field permeable
material without an additional shield.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] To assist in the understanding of the preferred embodiments
illustrated in the FIGS. 1 through 5, it will be assumed that
[0027] Magnetic shielding materials entrap magnetic flux at various
locations such as at the magnetic flux source or shield a sensitive
component. The optimum shielding strategy and shield location
typically involve performance, complexity of design, and cost
considerations. A passive shielding strategy is a type of magnetic
shielding strategy which relies on the interactions between
magnetic fields and special high permeability materials.
[0028] The dynamic interactions between AC and DC magnetic fields
and their role in a passive shielding strategy may involve six
parameters: frequency, attenuation, saturation, magnetic field
strength, magnetic flux density and material permeability.
[0029] The magnetic field strength, called the "H' field, describes
the intensity of a magnetic field in free space at some distance
away from its source. Field strength (H), measured in Oersteds
(Oe), is a function of the intensity of the magnetic source and the
distance from the source from which it is measured.
[0030] Magnetic flux density, called the "B" field, describes the
concentration of magnetic lines of force in a material. Flux
density (B) and Gauss (G) measures the number of magnetic lines of
force that reside in a square centimeter of material. The flux
density depends on intensity of a magnetic source, the distance of
the material from the magnetic source, and the material's
attractiveness to the magnetic fields.
[0031] Material permeability, indicated by the Greek symbol .mu.
(Mu), refers to a material's ability to attract and conduct
magnetic lines of flux. The more conductive a material is to
magnetic fields, the higher its permeability. The formula .mu.=B/H
shows that the permeability of a material can be determined by
measuring the magnetic field strength (H) at a point in free space
and then measuring the flux density (B) at that point after the
insertion of a material. The higher the permeability of the
material, the greater the concentration of the flux lines will
be.
[0032] A first preferred embodiment of the present invention is
illustrated by example in FIG. 1 showing a cantilever-style rotary
cathode with a magnetic field permeable material fixed to the
interior of the drive shaft. A high-power ion sputtering magnetron
10 includes a frame 12 as shown in FIG. 1.
[0033] Mostly recessed inside the frame 12 is a cooling system.
Coolant 14 in the form preferably of de-ionized water is
transported from a coolant supply (not shown) to a coolant inlet
16. A coolant conduit 20 is connected at one end to the coolant
inlet 16 and at the other end to a coolant outlet 18. The coolant
conduit 20 is made of electrically conductive material. The flow
direction can be designed to go either way as desired, such as from
the coolant outlet 18 through the coolant conduit 20 and out the
coolant inlet 16.
[0034] A vacuum chamber 22 is attached to the frame 12 of the high
power ion sputtering magnetron 10. Rotary vacuum seal and static
vacuum seals are used in conjunction with a vacuum pump (not shown)
to create a vacuum in the vacuum chamber 22.
[0035] An inert gas system is also incorporated into the ion
sputtering magnetron 10. Inert gas, such as Argon (not shown) is
transmitted from a gas supply (not shown) to a gas injection means
(not shown). The inert gas is finally transferred into the vacuum
chamber 22 to facilitate the sputtering process.
[0036] A rotary cathode device, such as a rotary cathode 30, is
rotatably mounted upon the ion sputtering magnetron 10. The
cylindrical-shaped cathode 30 includes a first end 32 and a second
end 34. FIG. 1 shows a cantilever-style 36 mounting of the cathode
30. The first end 32 is supported while the second end 34 is
unsupported in the cantilever-style mounting of the cathode 30. The
rotary cathode 30 comprises a drive shaft portion 38 and a target
portion 40. The drive shaft portion 38 includes an interior surface
and an exterior surface. The drive shaft portion 38 may be integral
with or rigidly attached to the target portion 40.
[0037] A conducting member, such as the coolant conduit 20, is
disposed longitudinally within the rotary cathode 30, specifically
within the drive shaft portion 38 and the target portion 40. The
coolant conduit 20 is made of an electrically conductive material
connecting an electrical current from the power source to the
rotary cathode 30. An electrical brush assembly 42 connects the
coolant conduit 20 with the target portion 40. A magnet array 44
depends from the coolant conduit 20 to near the interior surface of
the target portion 40.
[0038] The rotary cathode 30 further comprises an electromagnetic
field shield 50 attached to at least a portion of the interior
surface of the drive shaft portion 38. The electromagnetic field
shield 50 is made of an electromagnetic field-permeable material
such as a ferrous material or the like. The electromagnetic field
shield 50 is disposed between the conducting members such as the
coolant conduit 20 and the drive shaft portion 38. FIGS. 1, 2, and
3 show the electromagnetic field shield 50 attached to at least a
portion of the interior surface of the drive shaft portion 38.
Preferably, the electromagnetic field shield 50 is cylindrical in
shape and extends the entire length of the drive shaft portion
38.
[0039] Mounted to the frame 12 of the sputtering magnetron 10 is a
motor (not shown), which is of conventional design known in the
art. Optionally, the motor is connected to a gear reducer (not
shown). A drive connector (not shown), such as a drive belt, chain
or gearing, transmits power from the motor to the drive shaft
portion 38 of the rotary cathode 30. The drive shaft portion 38 is
integral with or is rigidly attached to the target portion 40 such
as by a threaded engagement to each other.
[0040] An electrical power supply (not shown) is connectable to a
power supply cable 54 of the sputtering magnetron 10. The other end
of the power supply cable 54 is connected to the coolant conduit
20. The electrical brush assembly 42 conducts electricity from the
coolant conduit 20 to the target portion 40.
[0041] In a single cathode system, generally using direct current
power, the anode (not shown) is a structure electrically connected
to the positive side of the power supply. Preferably, the anode is
inserted into, sealed and insulated from the vacuum chamber 22. The
anode floats at a potential greater than the rotary cathode 30.
Alternatively, the anode structure can also be the coater itself at
ground potential. In that case, the anode structure is again
greater than the rotary cathode 30 potential. The anode should be
accessible to the electrons emitted from the rotary cathode 30.
[0042] In a tandem rotary cathode 30 system utilizing alternating
current power, generally no separate anode structure is used. A
power supply cable 54 connected to the power supply is attached to
a rotary cathode 30. One rotary cathode 30 acts as the anode while
the other rotary cathode 30 functions as the cathode. Each rotary
cathode in the tandem cathode system alternates functions as a
current switches directions.
[0043] In operation, coolant 14 from a coolant supply (not shown)
is directed to the coolant inlet 16. Coolant then is directed
through the coolant conduit 20 and out a conduit aperture 74
adjacent to the second end 34 of the rotary cathode 30. The coolant
14 then flows from the target portion 40 interior into the drive
shaft portion 38 interior for providing the additional advantage of
cooling the electromagnetic field shield 50 before exiting through
the coolant outlet 18. The flow direction can be designed to go
either way as desired, such as from the coolant outlet 18 through
the coolant conduit 20 and out the coolant inlet 16.
[0044] From the target portion 40, electrons in the course of
completing a circuit, leave the negatively charged rotary cathode
30 and are attracted to the positively charged anode. The electrons
are then trapped in a magnetic field created by the magnet array
assembly 44. The electrons are repelled by the rotary cathode 30
while simultaneously being pulled toward the rotary cathode 30 by
magnetic field lines (not shown). An ion cloud or plasma is formed
between the magnetic array assembly 44 and the substrate 60. In
that plasma area, magnetic field lines carrying electrons intersect
inert gas molecules such as argon and the electrons ionize the gas
molecules. The positively charged ions in the plasma accelerate
toward the negatively charged target portion 40 and knock off atoms
from the target material located on the target portion 40. Finally,
those free atoms from the target material are deposited on the
substrate 60. The product is a coated substrate 60 such as a glass
window.
[0045] The portion of the stationary, electrically conductive
coolant conduit 20 within the drive shaft portion 38 creates an
electromagnetic field that produces inductive heating. The
electromagnetic field shield 50 protects heat-sensitive components
of the ion sputtering magnetron 10 such as the rotary seal and
static seals. Consequently, the parts susceptible to heat damage
and contribute to rotary cathode 30 failure are then protected,
reducing extensive replacement time and part costs.
[0046] The present invention provides an improved high-powered ion
sputtering magnetron which can be operated longer and less
expensively by fewer rotary cathode target replacements and when a
repair does become necessary, the rotary cathode target replacement
is faster and easier than preexisting replacements. The ion
sputtering magnetron has a simple and reliable electromagnetic
field shield which protects other heat-sensitive parts of the ion
sputtering magnetron and from inductive heat damage. Thus, the ion
sputtering magnetron of the present invention has the important
advantage of providing longer useful production to the owner and
operator thereof.
[0047] By redirecting the electricity through the empty interior of
the drive shaft, along a conducting member such as the coolant
conduit, electricity is directed to internal electrical brushes
and, therefore, to the target. One advantage of the feature is to
provide a place for a magnetic field shield between the coolant
conduit and the drive shaft. Another advantage is to provide
cooling of that magnetic field shield which is susceptible magnetic
inductive heating. This shield feature protects heat-sensitive
parts by absorbing fluctuating magnetic field that induces heating.
Other advantages include a directly cooled power train that allows
for higher input power; reduce shorting and arcing events inside
the cathode; more uniform coating and less frequent cathode target
changes. The field shield provides an additional advantage of
blocking electrical noise from the conducting member and/or coolant
conduit.
[0048] A second preferred embodiment of the present invention is
illustrated by way of example in FIG. 2 showing a double-ended
support-style rotary cathode in an ion sputtering magnetron with a
magnetic field permeable material affixed to the outside of the
drive shaft. A high-power ion sputtering magnetron 110 includes a
frame 112 as shown in FIG. 2.
[0049] A cooling system expands into the frame 112. Coolant 114 in
the form preferably of de-ionized water is transported from a
coolant supply (not shown) to a coolant inlet 116. A coolant
conduit 120 is connected at one end to the coolant inlet 116 and at
the other end to a coolant outlet 118. The coolant conduit 120 is
stationary and is made of electrically conductive material. The
flow direction can be designed to go either way as desired, such as
from the coolant outlet 118 through the coolant conduit 120 and out
the coolant inlet 116. The coolant inlet 116 and the coolant outlet
118 are shown running parallel to each other at the top of the
frame 112.
[0050] A vacuum chamber 122 is attached to the frame 112 of the
high power ion sputtering magnetron 110. Vacuum seals including a
vacuum rotary seal 170 and vacuum static seals 172 are used in
conjunction with a vacuum pump (not shown) to create a vacuum in
the vacuum chamber 122.
[0051] An inert gas system is also incorporated into the ion
sputtering magnetron 110. Inert gas, such as argon (not shown) is
transmitted from a gas supply (not shown) to a gas injection means
(not shown). The inert gas is directed into the vacuum chamber 122
facilitates charged ions in the sputtering process.
[0052] A rotary cathode device, such as a rotary cathode 130 is
rotatably mounted upon the ion sputtering magnetron 110. The
cylindrical-shaped cathode 130 includes a first end 132 and a
second end 134. FIG. 2 shows a two-end support-style 136 mounting
of the rotary cathode 130. Both the first end 132 is supported and
the second end 134 is also supported. The rotary cathode 130
comprises a drive shaft portion 138 integral with or rigidly
attached to a target portion 140. The drive shaft portion 38
includes an interior surface and an exterior surface. With this
invention, utilities running to both ends of the rotary cathode are
no longer necessary.
[0053] A conducting member, such as the coolant conduit 120, is
disposed longitudinally within the rotary cathode 130, specifically
within the drive shaft portion 138 and the target portion 140. The
coolant conduit 120 is made of an electrically conductive material
connecting an electrical current from the power source to the
rotary cathode 130. An electrical brush assembly 142 connects the
coolant conduit 120 with the target portion 140. A magnet array 144
depends from the coolant conduit 120 to near the interior surface
of the target portion 140.
[0054] The rotary cathode 130 further comprises an electromagnetic
field shield 150 attached to at least a portion of the interior
surface of the drive shaft portion 138. The electromagnetic field
shield 150 is made of an electromagnetic field-permeable material
such as a ferrous material or the like. The electromagnetic field
shield 150 is disposed between the conducting members such as the
coolant conduit 120 and the drive shaft portion 138. FIGS. 1, 2,
and 3 show the electromagnetic field shield 150 attached to at
least a portion of the interior surface of the drive shaft portion
138. Preferably the electromagnetic field shield 150 is cylindrical
in shape and extends the entire length of the drive shaft portion
138.
[0055] A motor 152 which is of conventional design known in the art
is mounted to the frame 112 of the sputtering magnetron 110.
Optionally, the motor 152 is connected to a gear reducer (not
shown). A drive connector (not shown), such as a drive belt, chain
or gearing, transmits power from the motor 152 to the drive shaft
portion 138 of the rotary cathode 130. The drive shaft portion 138
may be integral with or rigidly attached to the target portion 140
such as by a threaded engagement to each other or the like.
[0056] An electrical power supply (not shown) is connected to a
power supply cable 154 of the sputtering magnetron 110. The other
end of the power supply cable 154 is connected to the coolant
conduit 120. The electrical brush assembly 142 conducts electricity
from the coolant conduit 120 to the target portion 140.
[0057] In operation, coolant 114 from a coolant supply (not shown)
is directed to the coolant inlet 116. Coolant then is directed
through the coolant conduit 120 and out a conduit aperture adjacent
to the second end 134 of the rotary cathode 130. The coolant 114
then flows from the target portion 140 interior into the drive
shaft portion 138 interior for providing the additional advantage
of cooling the electromagnetic field shield 150 before exiting
through the coolant outlet 118. The flow direction can be designed
to go either way as desired, such as from the coolant outlet 118
through the coolant conduit 120 and out the coolant inlet 1 16.
[0058] The electromagnetic field shield 150 protects heat-sensitive
components of the ion sputtering magnetron 110 such as the rotary
seal and static seals from the electromagnetic field that produces
inductive heating. Consequently, the parts susceptible to heat
damage and contribute to rotary cathode 130 failure are then
protected, reducing extensive replacement time and part costs.
[0059] The significant benefit to such a configuration here is that
all utilities can be fed into just one end support in this
dual-support-style cathode configuration. This simplifies its
design and gives the added advantage of eliminating the utilities
normally directed to the other end support of the magnetron, such
as additionally eliminating power, coolant or drive, and a rotary
seal and all the other accompanying air-to-vacuum seals. The
importance of eliminating one of the two rotary seals can be
appreciated by the fact that rotary seal failure can be one of the
most frequent causes of cathode failure, so eliminating one of
these two rotary seals in the magnetron will reduce the need for
such repairs by 50%. Similarly, this design eliminates one of the
two sets of air-to-vacuum seals in the magnetron which will reduce
the need for such repairs with the resulting ultimate benefit of
significantly improved sputtering magnetron reliability and
improved plant productivity.
[0060] A second preferred embodiment of the rotary cathode device
invention is illustrated in FIG. 4. Electromagnetic field shield
250 surrounds the exterior of the drive shaft 238.
[0061] A third preferred embodiment of the rotary cathode device
invention is shown in FIG. 5. This embodiment can be used in any
style, such as the cantilever style or the two-ended support style.
The invention eliminates the need for an additional electromagnetic
field shield by making the drive shaft itself 338 be made of
electromagnetic field-permeable material, such as a ferrous
material.
[0062] While the present invention has been disclosed in connection
with the preferred embodiment thereof, it should be understood that
there may be other embodiments which fall within the spirit and
scope of the invention as defined by the following claims.
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