Abstract: A magnetron sputter comprises a carrier, a magnet assembly, at least a middle magnetic ring, a target and at least a conducting magnetic ring. The magnet assembly is disposed on a carrying surface of the carrier comprising a permanent magnet and an external magnetic ring. The middle magnetic ring is disposed between the permanent magnet and the external magnetic ring of the magnet assembly. The target is disposed above the magnet assembly having a first surface which faces the carrying surface. The conducting magnetic ring is disposed on the first surface.

Abstract: A supply end block to supply a sputter cathode with a coolant and electrical voltage, includes a housing with a coolant connection and a current connection as well as a support shaft mounted to rotate, on which a target tube is fastened. The coolant connection and current connection are brought together directly at a feed site so that the coolant is brought to the potential of the applied electric voltage on entering the housing of the end block. Optimal cooling of the current feed is achieved, and optimal potential equalization of the coolant simultaneously occurs.

Abstract: To provide a sputtering apparatus and method, and a sputtering control program which are configured simply and can secure the uniformity of the film thickness from the beginning to the end of the use of a target. There are provided: a target 15 disposed so as to face an object to be treated 19; a permanent magnet unit M which generates a high-density plasma by means of a magnetic field and deposits a material of the target 15 on the object to be treated, in the form of a film; a rotational mechanism 9 which rotates the permanent magnet unit M; and a rotation number control apparatus 7 which gradually changes the number of rotations of the permanent magnet unit M rotated by the rotational mechanism 9.

Abstract: A sputtering plasma reactors for plasma vapor deposition (PVD) having an improved interface between a PVD target, a ceramic ring and a PVD chamber wall. The reactor includes a PVD chamber wall and a PVD target, wherein the target in conjunction with the PVD chamber wall form a vacuum chamber and wherein at least the portion of the target facing the vacuum chamber is composed of material to be sputtered. The reactor also includes an insulating ceramic ring positioned between the target and the PVD chamber wall. A first O-ring is provided to establish a vacuum seal between the target and the insulating ring and a second O-ring is provided to establish a vacuum seal between the insulating ring and the PVD chamber wall. At least one spacer is positioned between the target and insulating ring to maintain a gap G between the insulating ring and the target.

Abstract: A sputtering magnetron (300) insertable in a rotatable target is described. The magnetron is designed around a single piece, multiwalled tube (102, 202) with compartments (316, 316?, 318, 318?) extending over the length of the tube. The multiwalled tube gives a much stiffer magnetron carrier structure compared to prior art magnetrons. As a result, the magnetic field generator can be mounted inside a compartment and the distance between magnets and target surface is easily adjustable as the tube is much stiffer than the generator. Additionally, the coolant channels can be incorporated inside the tube and close to the outer wall of the tube so that coolant can be supplied in the vicinity of the magnetic field generator. The increased stiffness of the magnetron allows the target tube to be carried by the magnetron—not the other way around—at least during part of the useful life of the target.

Abstract: The present invention is an alternating current rotary sputter cathode in a vacuum chamber. The apparatus includes a housing containing a vacuum and a cathode disposed therein. A drive shaft is rotatably mounted in the bearing housing. A rotary vacuum seal is located in the bearing housing for sealing the drive shaft to the housing. An at least one electrical contact is disposed between a power source and the cathode for transmittal of an oscillating or fluctuating current to the cathode. The electrical contact between the power source and the cathode is disposed inside of the vacuum chamber, greatly reducing, and almost eliminating, the current induced heating of various bearing, seals, and other parts of the rotatably sputter cathode assembly.

Abstract: A rotor having a cylindrical peripheral surface is disposed in a treatment vessel into which a carrier gas is introduced, and the rotor peripheral surface is opposed to the surface of a substrate with a predetermine gap therebetween. Film-forming particulates including atomic molecules of the film-forming material and cluster particulates thereof are scattered from the surface of the film-forming material supplying member by sputtering, and the rotor is rotated to form a carrier gas flow near the rotor peripheral surface. The film-forming particulates are transported to the vicinity of the surface of the substrate by the carrier gas flow and adhered to the surface of the substrate. As a result, the adverse effect of high-energy particles and the like is suppressed to efficiently form a satisfactory thin film by an evaporation or sputtering process, which has less restriction to a source material gas, without the need for large equipment.

Abstract: A method and apparatus for depositing a coating material on a surface of a substrate by an ion plasma deposition process using a hollow cathode is disclosed. The cathode may be a substantially cylindrical hollow cathode. A plasma arc is formed on the outer circumference of the cathode to remove coating material from the cathode, which is then deposited on a surface of a substrate. An internal arc drive magnet is contained within the hollow bore of the cathode and cooling is provided to the magnet during operation.

Abstract: A sputter apparatus with a pipe cathode is arranged such that the supply of power, cooling fluid and other media to the pipe cathode takes place via flexible lines or tubes which can be wound about a receptor. If the pipe cathode completes a pendulum movement, the lines and/or tubes are wound onto the receptor or wound from it. The pendulum movement of the pipe cathode is preferably such that the pipe cathode is rotated by a certain first angle in a first direction and subsequently by a certain second angle in a second direction, the second angle differing from the first angle. Methods for operating the sputter apparatus are also disclosed.

Abstract: An end-block for electrically energising a rotatable tubular target in a vacuum coating installation is disclosed. The end-block has a rotary electrical contact that reduces the joule heating effects when operating in alternating current mode. When compared to known end-blocks, this is achieved by increasing the number of contact areas between a contacting ring and a series of circumferentially mounted contacting shoes. Also the contact shoes are being pressed radially outwardly by means of resilient elements against the contacting ring.

Abstract: The invention relates to a target support assembly (1) comprising a support (2), on which a target lining is arranged. In order to simplify the production of the target lining or of the target support assembly and/or the placement of the target lining on the support, the target lining is formed by a target sleeve (4) that is slid onto the support (2). At least one clamping element (5) is placed, while actively clamping, between the support (2) and the target sleeve (4).

Abstract: Certain example embodiments relate to techniques for depositing transparent conductive oxide (TCO) coatings using dual C-MAG sputtering apparatuses. Certain example embodiments provide a closed-loop system with the following process conditions. About 90% of the oxygen gas provided to the apparatus is provided via a top gas inlet. Pressure within the apparatus is increased to about 10?3 to 10?2 mbar, e.g., by providing an inert gas flow of at least about 600 sccm in certain example embodiments. Tube rotation is reduced to less than about 5 RPM. The power provided to the apparatus is adjusted in dependence on the presence or absence of oxygen partial pressure oscillations. TCOs such as, for example, ITO, ZnAlOx, SnSbOx, may be deposited according to the techniques of certain example embodiments.

Abstract: A method and device for magnetron sputtering are provided. A magnetron coating system includes a first coating source and an auxiliary substrate arranged between the first coating source and an area into which a substrate to be coated is to be received. The system also includes a magnetron having a cathode composed of the auxiliary substrate. Additionally, the system includes a device structured and arranged to determine an area density of the auxiliary substrate.

Abstract: It is an object of the present invention to provide a sputtering apparatus capable of suppressing local consumption of axial end portions of a rotatable cylindrical target to make uniform an erosion area in the cylindrical target and thereby improving the service life of the cylindrical target. The apparatus includes a pair of sputter evaporation sources 2 each having a rotatable cylindrical target 13 and a magnetic field generating member 14 disposed inside the cylindrical target 13; and a sputter power source 3 for the supply of discharge electric power to the cylindrical targets 13, using the cylindrical targets 13 as cathodes. Both the cylindrical targets 13 are disposed in such a manner that the respective center axes are parallel to each other, and the magnetic field generating members 14 generate a magnetic field having magnetic lines of force acting in directions attracting through surfaces of the cylindrical targets 13.

Abstract: A dual magnetron for plasma sputtering in which two distinctly different magnetrons are mounted on a common plate rotating about a central axis in back of a target. At least one of the magnetrons is switched on and off by changes in chamber pressure or target power while the other magnetron, if it does switch, switches in complementary fashion. When the two magnetrons are mounted at different radii, the switching effects a effective movement of the magnetron such that different areas of the target are exposed to a sputtering plasma. In particular, a small unbalanced magnetron may scan the target edge to produce a highly ionized sputter flux and a larger magnetron positioned near the center can be switched on to clean sputter material redeposited on the target center.

Abstract: A sputter coating system comprises a vacuum chamber, means for generating a vacuum in the vacuum chamber, a gas feed system attached to the vacuum chamber, a gas plasma forming system attached to the vacuum chamber, a system for confining and guiding a gas plasma within the vacuum chamber, and a prism-shaped sputter target assembly, with the material to be sputtered forming at least the outer surface of the target assembly and positioned such that the outer surface is surrounded by the plasma within the vacuum chamber. A negative polarity voltage is applied to the surface of the material such that sputtering occurs.

Abstract: The invention relates to a method for operating a magnetron sputter cathode, in particular a tube cathode or several tube cathodes forming an array. In such cathodes a target passes through a magnetic field, whereby induction currents flow in the target which distort the magnetic field. This results in the nonuniform coating of a substrate. By having the relative movement between magnetic field and target alternately reverse its direction, the effect of the magnetic field distortion can be compensated. This yields greater uniformity of the coating on a substrate to be coated.

Abstract: A sputtering target includes an outer target tube, an inner support tube supporting a magnet carrier bar extending along substantially the entire length of the inner support tube; and a water cooling circuit including at least one passageway within the inner support tube with an inlet at one end thereof adapted to receive cooling water from an external source, at least one outlet aperture at an opposite end thereof opening to a cooling plenum radially between the inner support tube and the outer target tube; and a baffle comprising a substantially flat plate attached to the inner support tube adjacent the opposite end, the plate extending radially within the plenum between the inner support tube and the outer target tube and having an array of flow apertures therein.

Abstract: 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

Abstract: A sputtering target comprising an outer target tube, an inner support tube supporting a magnet carrier extending along substantially the entire length of the inner support tube; and a water cooling circuit including at least one passageway within the inner support tube with an inlet at one end thereof adapted to receive cooling water from an external source, at least one outlet aperture at an opposite end thereof opening to a cooling chamber radially between the inner support tube and the outer target tube; and a plurality of spiral vane segments attached to an outer surface of the inner support tube.

Abstract: The present invention is an alternating current rotary sputter cathode in a vacuum chamber. The apparatus includes a housing containing a vacuum and a cathode disposed therein. A drive shaft is rotatably mounted in the bearing housing. A rotary vacuum seal is located in the bearing housing for sealing the drive shaft to the housing. An at least one electrical contact is disposed between a power source and the cathode for transmittal of an oscillating or fluctuating current to the cathode. The electrical contact between the power source and the cathode is disposed inside of the vacuum chamber, greatly reducing, and almost eliminating, the current induced heating of various bearing, seals, and other parts of the rotatably sputter cathode assembly.

Abstract: An in-situ plasma cleaning device (PCD) performs an atomic surface cleaning process to remove contaminants and/or to modify the cylindrical surfaces of both the target and substrate. The atomic cleaning process utilizes a plasma generated locally within the in-situ plasma cleaning device with suitable properties to clean both the target and substrate cylindrical surfaces either concurrently or separately. Moreover, the in-situ plasma cleaning device is designed to traverse the length of the target and the substrate cylindrical surfaces during the cleaning process.

Abstract: The present invention provides a magnetron sputtering system using a gas distribution system which also serves as a source of anodic charge to generate plasma field. The sputtering system is comprised of a vacuum chamber, a cathode target of sputterable material, a power source which supplies positive and negative charge, and a gas distribution system. The gas distribution system may comprise a simple perforated gas delivery member, or it may comprise a perforated gas delivery member with an attached conductive anodic surface. The gas delivery member may also contain an inner conduit with further perforations which serves to baffle flow of the sputtering gas. Gas flow may be regulated within discrete portions of the gas distribution system. The anodic surfaces of the gas distribution system are cleaned through the action of plasma and gas flow, creating a more stable plasma and reducing the need for maintenance.

Abstract: An apparatus includes a plasma generator aligned with a beam generator for producing a plasma to shield an energized beam. An electrode is coaxially aligned with the plasma generator and followed in turn by a vortex generator coaxially aligned with the electrode. A target is spaced from the vortex generator inside a fluid environment. The electrode is electrically biased relative to the electrically grounded target for driving the plasma toward the target inside a vortex shield.

Abstract: A magnetron cathode and a sputtering apparatus including the same are provided. The magnetron cathode includes three or more magnet units, each of which comprises a single magnet or a plurality of magnets having the same poles facing toward the same direction, wherein one magnet unit is disposed around the outer circumference of another magnet unit and adjacent magnet units have opposite poles facing toward the same direction. Uniform magnetic field distribution is obtained. Therefore, the erosion profile of a target is wide and uniform.

Abstract: A plasma reactor for processing a semiconductor workpiece, includes a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece, an overhead electrode overlying said workpiece support, the electrode comprising a portion of said chamber wall, an RF power generator for supplying power at a frequency of said generator to said overhead electrode and capable of maintaining a plasma within said chamber at a desired plasma ion density level. The overhead electrode has a capacitance such that said overhead electrode and the plasma formed in said chamber at said desired plasma ion density resonate together at an electrode-plasma resonant frequency, said frequency of said generator being at least near said electrode-plasma resonant frequency.

Abstract: A cylindrical magnetron capable of running at high current and voltage levels with a target tube that is self cleaning not only in the center portion, but also at the ends. Sputtering the ends of the target tube virtually eliminates accumulation of condensate at the ends and any resultant arcing, resulting in a more reliable magnetron requiring less service and a magnetron that produces more consistent coatings.

Abstract: A plasma processing system is provided with a cylindrical target, open at both ends, and with a magnet array that forms a hollow cathode magnetron (HCM). At one of the open ends is placed an inductively coupled RF energy source. A dielectric window at one end of the cylindrical target forms a seal between atmosphere and the processing system. A deposition baffle shield permits the coupling of RF energy from the coil into the chamber. The open end of the cylindrical target opposite the RF source faces the processing space. Magnetron magnets produce a magnetic trapping field having a null which acts as a mirror and separates a plasma-source from the processing space.

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 conducting member that are susceptible to inductive magnetic heating.

Abstract: A magnetron system for a sputtering target having an annular vault facing the wafer to be coated and having inner and outer sidewalls and a roof. A small magnetron is positioned over the roof. A first magnet assembly having a first magnet polarity along the target axis is positioned behind the inner sidewall. A second magnet assembly having an opposed second opposed magnetic polarity is disposed in back of the outer sidewall and has magnetic strength much greater than the first magnet assembly but its strength is asymmetrically distributed about the target axis. The second magnet assembly and the roof assembly are rotated together about the target axis. The rotating asymmetric sidewall magnet assembly may also be used with a hollow-cathode target, with or without a roof magnetron.

Abstract: A system and method for reducing and controlling the number of defects due to carbon inclusions on magnetic media is disclosed. A diamond like carbon protective layer is deposited on magnetic media using a rotary cathode target assembly. The target and cathode are cylindrical in shape and are mounted on holder that allows the target and cathode to rotate while holding a magnet fixed. The target surface is periodically swept in through a plasma which sputters off the surface of the target. This prevents the build up of redeposited material on the target and consequently keeps the target surface cleaner. The reduction of redeposited material on the target surface reduces the number of unwanted particulates which are ejected from the surface, manifesting themselves as disk defects.

Abstract: A rotating sputtering target(s) is segmented so as to include a plurality of different sputtering material portions or segments radially dispersed around the outer periphery of the target. This enables a plurality of different layers to be sputter-deposited, one after the other, using the same sputtering target as the target rotates. The thicknesses of the different layers can be controlled by the radially extensive size of the different segments, the rotation speed of the target, the material sputter rate, the sputtering power used, and/or the line speed of the sputter coater in which the target(s) is located. One or more such targets may be used in a coater according to different embodiments of this invention.

Abstract: A tube target for cathode sputtering installations, and a process for producing a cylindrical hollow body for such a tube target and its use. The problem of providing a simple and low-cost process for producing a cylindrical hollow body for a tube target and of providing a cylindrical hollow body with a uniform, fine-grained structure is solved by the cylindrical hollow body being produced by centrifugal casting of a melt.

Abstract: A sputtering magnetron arrangement is disclosed, comprising a magnetic field generator (1) and a target (4) which is associated with said magnetic field generator (1). The magnetic field generator (1) includes a magnetically active element (5-9) and an adjusting means (20-25) which is adapted to deform or deflect locally the magnetically active element (5-9) so as to alter with respect to the target (4) the position of at least a portion of the magnetic field generator (1).

Abstract: A plasma sputter reactor including a target with an annular vault formed in its surface facing the wafer to be sputter coated and having inner and outer sidewalls and a roof thereover. A well is formed at the back of the target between the tubular inner sidewall. A magneton associated with the target includes a stationary annular magnet assembly of one vertical polarity disposed outside of the outer sidewall, a rotatable tubular magnet assembly of the other polarity positioned in the well behind the inner sidewall, and a small unbalanced magnetron rotatable over the roof about the central axis of the target.

Abstract: A cylindrical target having a cylindrical backing tube and hollow cylindrical target material disposed on an outer circumference of the cylindrical backing tube. The backing tube and the target material are joined via an electroconductive felt present beteween the backing tube and the target material.

Abstract: The invention provides methods and equipment for depositing films. In certain embodiments, there is provided a deposition chamber having a substrate-coating region and an electrode-cleaning region. In these embodiments, an electrode is positioned in the deposition chamber and has an interior cavity in which first and second magnet systems are disposed. In certain embodiments, there is provided a method for depositing films onto substrates using a deposition chamber of the described nature. The invention also provides electrode assemblies for film-deposition equipment. In certain embodiments, the electrode assembly comprises a rotatable electrode (optionally having an outer coating of carbon or the like) having an interior cavity, with stationary first and second generally-opposed magnet systems being disposed in this interior cavity.

Abstract: A cylindrical magnetron capable of running at high current and voltage levels with a target tube that is self cleaning not only in the center portion, but also at the ends. Sputtering the ends of the target tube virtually eliminates accumulation of condensate at the ends and any resultant arcing, resulting in a more reliable magnetron requiring less service and a magnetron that produces more consistent coatings.

Abstract: A cylindrical magnetron target and spindle attachment apparatus for affixing a cylindrical magnetron target to a rotatable support spindle. The attachment apparatus includes a target and a spindle. The target defines a receiving portion. The spindle has a spindle plug. The spindle plug is disposed within the receiving portion of the target. The attachment apparatus increases the speed and ease of removing and installing cylindrical rotating targets onto a support spindle.

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 conducting member that are susceptible to inductive magnetic heating.

Abstract: The invention provides a susceptor with a built-in plasma generation electrode that can make the throughput by a range of plasma processing of a plate specimen uniform, and that has excellent plasma resistance, thermal conductivity and durability, and a manufacturing method that can obtain this susceptor with a built-in plasma generation electrode easily and economically.

Abstract: A plasma-enhanced coaxial magnetron sputter-cleaning and coating assembly for sputter-cleaning and coating the interior surfaces of a cylindrical workpiece is provided. The apparatus sputter-coats the workpiece using a cylindrical sputtering material, the material having an interior and an exterior. The apparatus includes a core cooling system surrounded by a ring magnet assembly including a plurality of axially aligned ring magnets, with the core cooling system and the ring magnet assembly axially aligned with, and residing in the interior of, the cylindrical sputtering material. A cylindrical-shaped filament circumferentially surrounds the exterior of the cylindrical sputtering material. An anode comprised of a wire screen circumferentially surrounds, and is external to the filament; whereby the apparatus for plasma-enhanced coaxial magnetron sputter-cleaning and coating may be housed inside the workpiece in order to sputter-clean and coat the interior of the workpiece.

Abstract: The present invention is an alternating current rotary sputter cathode in a vacuum chamber. The apparatus includes a housing containing a vacuum and a cathode disposed therein. A drive shaft is rotatably mounted in the bearing housing. A rotary vacuum seal is located in the bearing housing for sealing the drive shaft to the housing. An at least one electrical contact is disposed between a power source and the cathode for transmittal of an oscillating or fluctuating current to the cathode. The electrical contact between the power source and the cathode is disposed inside of the vacuum chamber, greatly reducing, and almost eliminating, the current induced heating of various bearing, seals, and other parts of the rotatably sputter cathode assembly.

Abstract: A source of sputtered deposition material has, in one embodiment, a torus-shaped plasma generation area in which a plasma operates to sputter the interior surface of a toroidal cathode. In one embodiment, the sputtered deposition material passes to the exterior of the source through apertures provided in the cathode itself. A torus-shaped magnetic field generated in the torus-shaped plasma facilitates plasma generation, sputtering of the cathode and ionization of the sputtered material by the plasma.

Abstract: A support assembly for the magnetic array in a cylindrical magnetron that greatly reduces the stress placed on the assembly and on the end blocks of the magnetron. The support assembly and method also reduce the time necessary for properly positioning the magnetic array in relation to the target tube, and result in uniform positioning of the magnetic array along the length of the target tube. A cylindrical magnetron incorporating such an assembly produces uniform coatings and requires less adjustment and maintenance.

Abstract: The present invention provides a magnetron sputtering system using a gas distribution system which also serves as a source of anodic charge to generate plasma field. The sputtering system is comprised of a vacuum chamber, a cathode target of sputterable material, a power source which supplies positive and negative charge, and a gas distribution system. The gas distribution system may comprise a simple perforated gas delivery member, or it may comprise a perforated gas delivery member with an attached conductive anodic surface. The gas delivery member may also contain an inner conduit with further perforations which serves to baffle flow of the sputtering gas. Gas flow may be regulated within discrete portions of the gas distribution system. The anodic surfaces of the gas distribution system are cleaned through the action of plasma and gas flow, creating a more stable plasma and reducing the need for maintenance.

Abstract: A sputtering target having an annular vault with a throat between two sidewalls and facing a substrate to be sputter coated. The vault is partially closed by a plate placed in the annular throat between the sidewalls. Thereby, the plasma density is increased within the vault. Furthermore, the position of the annular gap in the plate between the two sidewalls may be chosen to increase uniformity of sputtering deposition arising from the two sidewalls. The plate may be formed of one or more annular rings attached to the walls or a single plate having apertures formed therein may bridge the throat. Alternatively, the target may be formed as a cylindrical hollow cathode with the plate partially closing the circular throat. A rotating asymmetric roof magnetron may be combined with a hollow cathode without the restricting plate.

Abstract: An AC/DC cylindrical magnetron with a drive system that absorbs large variations in the rotation of the target tube, an efficient high capacity electrical transfer system, and improved electrical isolation.

Abstract: A rotary target for use in a physical deposition process. The rotary target comprises at least one rotary target segment mechanically disposed on a backing tube.

Abstract: A facing target sputtering apparatus, comprising: inner and outer spaced-apart, concentric, and coextensive tubular cathodes open at each end, with the inwardly facing surface of the outer cathode and the outwardly facing surface of the inner cathode; a first pair of ring-shaped magnet means extending around the outwardly facing surface of the outer cathode at the ends thereof, with a first polarity magnetic pole facing the outwardly facing surface; a second pair of ring-shaped magnet means extending around the inwardly facing surface of the inner cathode at the ends thereof, with a second, opposite polarity magnetic pole facing the inwardly facing surface; and a substrate positioned in spaced adjacency to an end of the inner and outer cathodes; wherein: magnetic flux lines from the first and second pairs of magnet means uni-directionally pass through portions of an annularly-shaped space between the ends of the inner and outer cathodes, and during sputtering operation, plasma is substantially confined t