Magnetron sputtering apparatus and method for depositing a coating using same

A method for depositing a coating using a magnetron sputtering apparatus and a magnetron sputtering apparatus comprising: a support structure comprising a hollowed shaft comprising a central conduit having a longitudinal axis; a sputter target material defining a bore which is external to the central conduit, the bore also having the longitudinal axis a magnet assembly supported about the support structure, the magnet assembly having a first end, a second end, and a plurality of magnets supported therebetween and being effective, upon rotation, to generate a circumferential external magnetic field about the sputter target material; a first sealed end extending radially inward from adjacent the sputter target material proximate the first end of the magnet assembly and a second sealed end extending radially inward from adjacent the sputter target material proximate the second end of the magnet assembly, wherein the first sealed end, the second sealed end, and the sputter target material seal the magnet assembly therebetween; a cooling system comprising one or more coolant passage extending through the magnet assembly, the central conduit comprising a coolant inlet and a coolant outlet at the first sealed end; and, one or more rotors supported about the support structure and rotatable therewith by coolant passing through the one or more coolant passages.

FIELD OF THE APPLICATION

The present application relates generally to a system, apparatus, and method of depositing a coating on a workpiece.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to the application entitled “Method for Magenetron Sputter Deposition,” filed simultaneously herewith.

BACKGROUND

Tubular workpieces, such as gun barrels and engine cylinders, often require hard, wear-resistant, and/or corrosion resistant interior coatings. A number of techniques have been used to coat interior tubular surfaces, including magnetron sputtering. Unfortunately, the magnetron sputtering systems used to form such coatings generally have been inefficient and/or ineffective. More efficient and effective methods for applying such coatings are needed.

BRIEF SUMMARY

In one embodiment, the present application provides magnetron sputtering apparatus comprising: a support structure comprising a hollowed shaft comprising a central conduit having a longitudinal axis; a sputter target material defining a bore which is external to the central conduit, the bore also having the longitudinal axis; a magnet assembly supported about the support structure, the magnet assembly having a first end, a second end, and a plurality of magnets supported therebetween and being effective, upon rotation, to generate a circumferential external magnetic field about the sputter target material; a first sealed end extending radially inward from adjacent the sputter target material proximate the first end of the magnet assembly and a second sealed end extending radially inward from adjacent the sputter target material proximate the second end of the magnet assembly, wherein the first sealed end, the second sealed end, and the sputter target material seal the magnet assembly therebetween; a cooling system comprising one or more coolant passages extending through the magnet assembly, the central conduit comprising a coolant inlet and a coolant outlet at the first sealed end; and, one of more rotors supported about the support structure and rotatable therewith by coolant passing through the one or more coolant passages.

In one embodiment, the application provides a method for depositing a coating using a magnetron sputtering apparatus, the method comprising: providing in a vacuum a hollowed workpiece having an interior surface defining a bore having a first longitudinal axis; positioning along the first longitudinal axis a magnetron comprising a sputter target material supported around a support structure supporting one or more rotors and a magnet assembly, the sputter target material being positioned substantially radially equidistant from the interior surface of the bore; introducing fluid into a cooling system sealingly retained in the magnetron in a manner effective to cause the one or more rotors and the magnet assembly to rotate and to generate an external circumferentially directed magnetic field about the sputter target material; generating plasma in the vacuum; and, applying an electric potential to initiate ionization of the plasma and bombardment of the sputter target material to sputter target particles therefrom, thereby depositing a substantially uniform coating comprising the sputter target material on the interior surface of the bore.

DETAILED DESCRIPTION

The present application provides a system, apparatus, and method of depositing a coating on an interior surface of a substrate or workpiece utilizing a magnetron sputtering process. The method of deposition is implemented through operation of a magnetron sputtering system or assembly that includes a magnetron sputtering apparatus (“magnetron”) and the workpiece. The magnetron comprises a sputter target material, from which sputter material is ejected and directed to the workpiece surface to be coated.

The workpiece is positioned in the vicinity of the magnetron and preferably, such that the interior surface to be coated is facing the sputter target material. The system, apparatus, and method herein are particularly suited for depositing a coating on a hollowed workpiece. Suitable workpieces comprise a hollow or space defined by an interior wall in which the magnetron is positioned. More preferably, the hollowed workpiece comprises a tubular structure having an elongated bore defined substantially by the interior surface to be coated and within which the magnetron is positioned during the deposition process. Examples of such workpieces include, but are not necessarily limited to gun barrels, engine cylinders, piping components, and other tubular structures.

FIGS. 1-5depict an exemplary magnetron sputtering system (“magnetron”) and/or apparatus according to the present application.FIGS. 1-5are exemplary only, and should not be interpreted as limiting the application to the systems, apparatus, and methods specifically illustrated in these Figures and/or described in the corresponding description.

The term “magnetron sputtering system” or “magnetron” refers to the system or assembly that includes the workpiece and other components or equipment used to implement the magnetron sputtering process. In its basic form, the magnetron comprises a magnet assembly and support for the magnet assembly. The magnetron also preferably comprises the sputter target material and negative biasing apparatus for negatively biasing the sputter target material.

Referring toFIG. 1, a magnetron sputtering system200includes a magnetron sputtering apparatus or magnetron202, a hollowed workpiece206, and a vacuum chamber210housing both components. The hollowed workpiece206has an interior surface206aon which a coating208is deposited and a cylindrical bore206bhaving a radius, R, and a longitudinal axis, XX. The magnetron202includes a sputter target material204, a magnet assembly212spaced radially inward of the target material204, and a support structure214, preferably a ferromagnetic support structure214, about which magnets216are supported.

The magnetron202preferably is centrally positioned about the longitudinal axis XX of the bore206band extends substantially in excess of or about the length of the workpiece206. As shown inFIG. 1, the interior surface206ais spaced radially outward from the sputter target material204. Thus, the magnetron202is disposed substantially within the bore206bof the workpiece206. Preferably, the magnetron202is positioned substantially radially equidistant from the interior surface206aof the workpiece along the longitudinal axis of the interior surface206a.“Substantially radially equidistant” includes a variation of about less than 10% of the diameter V of the sputter target material204. In a preferred embodiment, the variation is less than 1% of the diameter V of the sputter target material204.

The sputter target material204may be substantially any material which may be sputter deposited onto the interior surface206a.The sputter target material204preferably is an elongated cylinder which, when centrally positioned within the hollowed workpiece206, also has longitudinal axis XX. The following are substantially coaxial and located radially outward relative to one another: the external diameter of the support214(S); the external diameter of the magnet assembly (T); the internal diameter of the sputter target material204(U); the external diameter of the sputter target material (V); and the internal diameter of the interior surface206a(R).

The support214may be made of a variety of materials effective to support the magnets without interfering with the coating process. The support214preferably comprises ferromagnetic material, most preferably iron or carbon steel. The cross-section of the support214may be rounded, rectangular, or any other shape suitable to support the magnet assembly212having a diameter sufficiently small to permit the support to be centrally positioned within the longitudinal bore of the sputter target material204. In one embodiment, discussed below, the support structure214has or incorporates an elongated bore or a hollowed shaft that serves as a conduit and a rotatable drive shaft.

The magnetron sputtering system200comprises a vacuum chamber port220and a pump230in fluid communication with the vacuum chamber210. The vacuum chamber210includes a gas feed240for providing a suitable gas for plasma generation. Suitable gases include inert gases, which include, but are not necessarily limited to argon, krypton, xenon, and combinations thereof. A preferred inert gas is argon. Where the coating is a ceramic coating, one or more reactive gas also is provided. Suitable reactive gases comprise an element selected from the group consisting of nitrogen and carbon in a form which reacts with ceramic precursor material to produce a ceramic coating. Examples of suitable reactive gases include, but are not necessarily limited to gaseous nitrogen, methane, acetylene, oxygen, ammonia, and combinations thereof.

The magnetron sputtering system200also preferably provides an energy source for negatively biasing the sputter target material204and an energy source for negatively biasing the inside surface206aof the workpiece206. In a preferred embodiment, the energy sources are voltage sources V1and V2, respectively and associated circuitry.

A rotatable drive mechanism (partially represented and denoted by numeral250inFIG. 1) is another preferred component of the magnetron sputtering system202. The rotatable drive mechanism250may be in the form of an assembly including a motor, drive shaft, and a coupling connection with the support structure214. The rotatable drive mechanism250may further include a programmable logic controller or equivalent controller means for controlling rotation of the magnet assembly212during the magnetron sputtering operation. The rotatable drive mechanism202is operated to rotate the magnet assembly212relative to the sputter target material204, thereby enhancing the deposition process, promoting a more uniform coating on the interior surface206a,and increasing the utilization of the sputter target material.

The magnet assembly212preferably comprises elongated magnets216mounted along the support214having a central axis XX. More preferably, the magnets216are rectangular or bar magnets216circumferentially spaced apart from one another about the support214, as shown inFIG. 1A. The phrase “circumferentially spaced apart” means that the magnets216are positioned at spaced intervals about the perimeter (“circumference”) of the support214. Such an arrangement does not require the support structure214to have a specific shape or cross section. The support structure214may have a circular, elliptical, rectangular, or any other number of suitable cross sections. Further, the magnets216may be arranged in a circular or non-circular pattern.

Referring specifically toFIG. 1A, the magnets216have an internal surface or pole216e,216f,216g,and216hin contact with the support structure214and an opposed, external surface or pole216a,216b,216c,216dpositioned radially outward of the support structure214. The internal and external surfaces, respectively, have opposite North or South polarities and the magnetic field within the magnets may be directed radially inward or outward depending on the polarity orientations. InFIG. 1A, the magnets216are illustrated with an indication of the polarity at the external surfaces216a,216b,216c,216d.As best shown in the end view ofFIG. 1A, an even number of bar magnets are circumferentially spaced apart on the support214. Preferably, four bar magnets216are circumferentially spaced apart by about 90°. The magnets216are further arranged about the structural support214such that the exposed surfaces of circumferentially adjacent magnets (e.g.,216aand216b) have opposite polarity orientations. It should be understood that other even numbers of rows (e.g., 2, 6, 8, 10, etc.) may also be used depending on the size of the magnetron.

Referring back toFIG. 1, each row of magnets216a-216dis preferably divided into segments216i,216j,216k,and216(l). The segments216i,216j,216k,and216(l) of each row are mounted so that all of the segments of the same row have the same polarity orientation. For example,FIG. 1illustrates two rows of magnets216aand216cspaced at substantially 180°. Each segment216i,216j,216k,216(l) in a row216a,216b,respectively, has the same North-South polarity orientation.

The magnets generate a circumferential magnetic field, or a magnetic field directed from one row of magnets to successive rows of magnets about the perimeter of the cylindrical sputter target material204. Preferably, the magnets generate a “circumferential external magnetic field” M having a magnetic field orientation which travels circumferentially from one circumferentially spaced magnet216ato the next successive circumferentially spaced magnet216boutside of the external diameter V of the cylindrical sputter target material204. This contrasts with the typical magnetic field, which travels along the longitudinal axis XX of the magnetron sputtering system200. The magnets generally produce a magnetic field of about 500 Gauss or more, preferably about 1000 Gauss or more.

Because of the geometric characteristics of the magnet assembly212, the ion current density generated is relatively uniform along the length and circumference of the sputter target material204. The ion current density generally is from about 0.01 mA/cm2to about 500 mA/cm2, preferably about 20 mA/cm2. In a preferred embodiment, circumferential uniformity is further promoted by rotating the sputter target material204relative to the workpiece206. Rotation at optimal speed may be accomplished by operation of the rotatable drive mechanism250.

The rate of decay of the sputter material and the deposited coating208are also substantially uniform, even when the sputter target material204and workpiece206are positioned in close proximity. Preferably, greater than 50 wt. % of the target material is used, more preferably 70 wt. % or more, even more preferably 80 wt. % or more, even more preferably 90 wt. % or more, and most preferably 95 wt. % or more of the target is utilized. This is, in itself, a design advantage provided by the magnetron sputtering system according to the present application, which is further exemplified in the design variations ofFIGS. 2-5.

The magnetron sputter assembly in each ofFIGS. 1-5is useful to deposit substantially any coating material amenable to sputter deposition. The sputter target material204may be selected on the basis of application requirements, including but. not necessarily limited to wear resistance, corrosion resistance, high temperature erosion resistance, and combinations thereof. Examples of coatings that may be deposited using the magnetron include, but are not necessarily limited to metallic coatings and ceramic coatings. Suitable metallic coatings include, but are not necessarily limited to coatings comprising a metal selected from the group consisting of tantalum, titanium, aluminum, iron, copper chromium, platinum, palladium, tungsten, and combinations thereof. Suitable ceramic coatings include, but are not necessarily limited to titanium nitride, chromium carbide, aluminum oxide, titanium carbonitride, chromium nitride, aluminum nitride, tungsten nitride, and tungsten carbide.

Once the sputter target material204and magnetron202are centrally positioned within the workpiece206, the magnetic sputter assembly is exposed to sputter deposition conditions effective to produce a substantially uniform coating. The sputter deposition conditions will vary with the particular coating. Preferably, the vacuum is pumped down to a base pressure of 10−6to 10−5Torr. Preferably, the interior surface of the workpiece206ais first cleaned to remove superficial contaminants. An inert gas, such as argon gas, is backfilled into the chamber to a pressure sufficiently high to cause the magnetron to function stably as to sputter target material to deposit onto the workpiece. Suitable pressures generally are from about 10−4to about 10−1torr, preferably from about 0.1 to about 50 millitorr, most preferably 5 millitorr.

In a preferred embodiment, the magnet assembly212is biased with RF (radio frequency), DC, or pulsed DC, and the workpiece206is biased with DC or pulsed DC. Depending on the applied power to the magnetron and the bias voltage to the tube, coatings may be formed at temperatures as low as about 100° C., or as high as about 500° C. The biasing conditions, and the sputter deposition conditions, are maintained for a duration necessary to deposit a coating having a desired thickness. Generally, the thickness is from about 0.1 μm to about 200 μm. The time required to sputter deposit the desired thickness generally is from about 10 minutes to about 300 minutes, most preferably for about 120 minutes.

When the magnetron is biased with RF, the magnetron biasing conditions comprise RF having a pulse frequency of about 100 kHz to about 15 MHz, preferably about 13.56 MHz, at a power of from about 0 kW to about 3 kW, preferably about 1 kW, depending on the size of the magnetron.

When bias is DC or pulsed DC, the magnet assembly and/or the workpiece biasing conditions comprise a pulse frequency of from about 100 Hz to about 3 kHz, preferably from about 1 kHz to about 2 kHz, a pulse width of from about 5 microseconds to about 300 microseconds, preferably about 20 microseconds. The magnetron biasing conditions comprise DC voltage of about 1000 V or less and pulsed DC voltage of about 100 V to about 1200V and a power of from about 100 W to about 5 kW depending on the size of the magnetron. In a preferred embodiment, the magnetron biasing conditions comprise a power of about 1 kW, preferably for a magnetron having a diameter of about 2″ and a length of about 24″. The workpiece biasing conditions are substantially the same as the magnetron biasing conditions with the exception of reduced voltage and consequently reduced power. The workpiece biasing conditions generally comprise about 1000 V or less, preferably from about 0 to about 500 V, more preferably abut 250 V, most preferably about 50 V.

Where the coating is a metallic coating, a sputter target material204comprising one or more selected metal is mounted on supports about the magnet assembly212. Before initiating the actual sputtering of the target material, the pump230is operated to evacuate the vacuum chamber210to a pressure of about 10−6to 10−5torr. A suitable gas is introduced into the vacuum chamber210. For deposition of a metallic coating, suitable gases are inert gases, which include, but are not necessarily limited to argon, krypton, xenon, and combinations thereof. This gas is fed into the chamber210under sputter deposition conditions effective to produce a substantially uniform coating of the particular metal. In a preferred embodiment, the gas is substantially continuously fed into the chamber through the duration of the process.

The magnetron202is biased, preferably negatively biased. The magnetron may be biased with radio frequency (RF) or negative voltage in the form of DC power or pulse DC power. Where DC power or pulse DC power is used, voltage control V1is activated to negatively bias the magnet assembly212and voltage control V2is activated to ground or negatively bias the workpiece206.

Positive ions from the plasma are accelerated toward the negatively charged sputter target material204with sufficient energy to remove or sputter target particles from the sputter target material204. Electrons freed during the ion bombardment process are confined by the magnetic field, M, generated around the sputter target material204and contribute to further ionization. In the meantime, the sputtered particles and are deposited onto the interior surface of the workpiece206to form a substantially uniform metallic coating208having a desired thickness. As used herein, a “substantially uniform coating” refers to the interior surface being completely covered by a coating having a desired thickness, preferably, a coating having a uniformity of thickness of about +/−20% or less of the desired coating thickness along its length.

In another embodiment, a ceramic coating is deposited onto the interior surface of the tubular workpiece. A suitable target material204is first selected depending on the type of ceramic coating to be formed, the characteristics of the workpiece206, and the desired characteristics of the coating itself. The sputter target material generally comprises silicon or the metal component of the ceramic. Preferred sputter target materials include, but are not necessarily limited to titanium, chromium, aluminum, silicon, tungsten, molybdenum, boron, and combinations thereof. The vacuum chamber210is pumped down to about 10−6to 10−5torr. Then, a reactive gas effective to form the desired ceramic is fed to the chamber. Suitable reactive gases for the formation of ceramic coatings include, but are not necessarily limited to nitrogen, methane, acetylene, oxygen, ammonia, and combinations thereof. In a preferred embodiment, the reactive gas further comprises an inert gas, preferably argon. The assembly is subjected to sputter deposition conditions effective to produce a substantially uniform ceramic coating.

For example, where the ceramic coating is TiN, titanium is chosen as the sputter target material. After adjusting the pressure in the chamber, a combination of argon and nitrogen at a ratio of about 80 vol. % to 20 vol. % is fed to the chamber at a rate of about 200 standard cubic centimeters per minutes (SCCM). The biasing mechanism is activated to negatively bias the magnet assembly212, and to either ground or negatively bias the workpiece206. The magnetron202is activated, and titanium atoms are sputtered from the titanium sputter target material and deposited onto the interior surface206aof the workpiece206. The chamber conditions are effective to induce the reactive gas (nitrogen) to react with the metal (Ti) to form the desired coating (e.g., N reacts with Ti to form TiN). For TiN, the conditions include a temperature of about 400° C. The process is continued for a period sufficient to form a substantially uniform coating of TiN having a thickness of from about 0.5 micrometers to about 3 micrometers. This generally requires a time period of about 3 hours. Upon completion, the coated workpiece206is removed from the vacuum chamber210.

In another embodiment, a ceramic coating is deposited onto the interior surface of the hollowed workpiece, preferably a tubular workpiece, via sputtering a ceramic target. Substantially any ceramic target may be used as long as it is amenable to sputtering. Preferred ceramic targets for this embodiment include, but are not necessarily limited to titanium boride and tungsten carbide.

FIG. 2illustrates a variation of the magnetron sputtering system300ofFIG. 1. Specifically,FIG. 2depicts a magnetron sputtering system300wherein the workpiece306provides, at least partially, the walls of the vacuum chamber308. In this magnetron sputtering system300, the ends of the hollowed workpiece306are sealed, via a cap, plate or equivalent sealing means, so as to complete the vacuum chamber310. The magnetron302, including magnets316and cylindrical sputter target material304, are centrally situated within the vacuum chamber310.

As with the magnetron sputtering system200ofFIG. 2, the vacuum chamber310, or more specifically, one of the sealed ends360, is provided with a port320in fluid communication with a pump330. The magnetron sputtering system300also comprises appropriate power supplies, gas feeds, and other components. See, e.g., U.S. Pat. No. 6,767,436, incorporated herein by reference.

The magnet assembly312comprises magnets316in an arrangement effective to generate a circumferential magnetic field about the sputter target material304. The circumferential magnetic field preferably is effective to produce a substantially uniform sputter deposited coating and to use greater than 50 wt. %, preferably 70 wt. % or more, more preferably 80 wt. % or more, even more preferably 90 wt. % or more, most preferably 95 wt. % or more of the sputter target material304. It is not necessary to widen the space between the sputter target material304and the interior surface306aof the workpiece306in order to achieve uniform deposition of coating on the interior surface of the workpiece. Accordingly, a uniform coating is formed even on workpieces having relatively small bores, preferably as small as 2 inches or less, more preferably as small as 1 inch or less.

FIG. 3depicts another variation of the magnetrons202,302ofFIGS. 1 and 2, respectively. In this embodiment, the magnetron402includes sealed end caps460a,460bthat enclose the magnetron402and, as further described below, enclose a cooling system.

The magnetron402is centrally situated within the bore of the workpiece (not shown). As with the magnetrons ofFIGS. 1 and 2, the magnetron402includes a magnet assembly412of segmented bar magnets416supported about an elongated support structure414. The magnet assembly412is arranged to generate a circumferentially directed magnetic field about the sputter target material404. The support structure414is amended, in this design variation, by provision of an inner shaft or support tube472. The support tube472defines a central longitudinal conduit474that extends from one end of the magnetron402to the opposite end.

As best shown in the cross-sectional view ofFIG. 3A, the cylindrical sputter target material404is mounted about an outer support tube470. The support tube470is spaced radially outward of the magnets416, thereby providing a circumferential gap482therebetween. The ends of the support tube470are sealingly engaged by end plugs460a,460bto enclose the magnets416therebetween and to form a sealed interior and cooling system.

The magnetron402ofFIG. 3comprises an integrated coolant system with a plurality of coolant passages passing adjacent to the magnet assembly412. The central conduit474provides one coolant passage. In particular, the central conduit474provides a return, hot coolant passage. Referring toFIG. 3B, a coolant distributor plate476is mounted about the inner tube472just across each end cap460a,460b.The distributor plates476include a plurality of ports478that are aligned with the channel space between the magnets416(see e.g.,FIG. 3D). The distributor plates476further include a port for the central conduit474.

Referring toFIG. 3C, a rotor480is situated inwardly of each distributor plate476. Preferably, the rotor480is mounted about the inner tube472and just forward of the magnet assembly412, and such that rotor blades480aof the rotor480are positioned in the coolant passage. The rotor blades480ainteract, therefore, with coolant passing through the coolant passage. Specifically, the moving coolant imparts fluid momentum upon the rotor blades480a,thereby rotating the rotor480. The rotor480, which is fixedly connected with the rest of the support structure414, rotates around the inner tube472. In this way, the magnet assembly412is rotated relative to the sputter target material404.

In further variations, the rotor480may be mounted on a bearing mounted on the inner tube472. In this design, the rotor480is rotatable independent of the inner tube472. Instead, the rotor480may be fixed directly to the rest of the support structure414or to the magnet assembly412. In further configurations, the rotor blades480amay be connected with the sputter target material404or the outer support tube470. In these further configurations, rotation of the rotor480effects rotation of the sputter target material404relative to the magnet assembly412.

The rotatable drive mechanism is energized by momentum of the flowing coolant in the cooling system (rather than an electrical source such as an external motor). Preferably, the coolant is pumped by an external pump or pressure differential (e.g., liquid head).

Coolant enters the magnetron402through a coolant inlet486and passes through the first distributor plate476(see arrows inFIG. 3), and then past the rotor480. From the ports478, the coolant passes through the magnet assembly412by way of channels between the rows of magnets416, thereby convectively cooling the magnets416. Coolant also passes by the outer support tube470and through the circumferential gaps482. By convectively cooling the outer support tube470, the coolant also cools the sputter target material404. The second distributor plate476at the second end provides an outlet of the coolant and directs the hot coolant into the central conduit474. The hot coolant returns through the central conduit474and out through an outlet488at the first end of the magnet. The hot coolant may be re-circulated by way of a suitable heat exchange system.

FIG. 4provides a variation of the magnetron402ofFIG. 3. A magnetron502according to this design employs a magnet assembly512that is arranged similarly to that of the magnetron402inFIG. 3and generates a magnetic field having the same characteristics. The magnetron502also includes a cylindrical sputter target material504disposed about an outer support tube570. The outer support tube570is spaced radially outward of the magnet assembly512to form a circumferential gap582therebetween. In contrast to the magnetron402ofFIG. 3, the support structure514does not include an inner tube472; the magnetron502includes, instead, an inner shaft590about which the rest of the support structure514is mounted. As with the magnetron402ofFIG. 3, the magnetron502is provided with end caps or plugs560a,560b,to enclose the interior and a coolant system therein. The magnetron502is provided, however, with a coolant inlet586on a first end and a coolant outlet588on the second, opposite end. The solid shaft590does not provide a coolant return conduit as with the magnetron402ofFIG. 3, but does support rotor580.

In this design, coolant enters through the inlet586and is directed along channels extending between the magnets516and through the circumferential gap582. The hot coolant is discharged at the second end through the coolant outlet588. As before, the passing coolant rotates the pair of rotors580, thereby rotatably driving the support structure514and the magnet assembly512during the sputter deposition process.

FIG. 5illustrates, in simplified form, yet a further variation of the magnetrons depicted inFIGS. 1-4. Operation of this magnetron602effects direct cooling of the sputter target material604, as well as the assembly612of magnets616. As with the magnetron502ofFIG. 4, the magnetron602of this design is provided with a coolant inlet686at one end and a coolant outlet688at a second, opposite end. The magnetron602does not, however, employ an outer tube (see e.g. outer tube570) about which the sputter target material604is mounted. The sputter target material604is directly spaced across from the magnet assembly612, thereby defining a circumferential gap682therebetween. End caps or plugs660a,660bare provided at the ends of the magnetron602to sealingly engage the cylindrical sputter target material604, thereby enclosing the interior of the magnetron602.

In the operation of the magnetron602, coolant is directed through the inlet686and through the channels between the magnets616and the circumferential gap682, thereby directly convectively cooling the magnets616as well as the sputter target material604. The hot coolant is then discharged at the opposite end and through coolant outlet688. Passing of the coolant through the cooling system also rotates rotors680, thereby rotating the magnet assembly612relative to the sputter target material604during the deposition process.

Persons of ordinary skill in the relevant chemical, mechanical, and other relevant art will recognize that further modifications and variations may be made to the structures, methods, and assemblies described in respect toFIGS. 1-5, without departing from the spirit and scope of the present application. Processes and structures previously described are meant to be illustrative only and should not be taken as limiting the application, which is defined by the claims below. The Figures have also been described and illustrated so as to explain the best modes for practicing the system, apparatus, and method according to the application.