WO2011062943A2

WO2011062943A2 - Planar magnetron sputtering source producing high target utilization and stable coating uniformity over lifetime

Info

Publication number: WO2011062943A2
Application number: PCT/US2010/056949
Authority: WO
Inventors: James G. Rietzel; Hans Peter Theodorus Ceelen; Leszek Malaszewski; Daniel J. Zehm
Original assignee: Applied Materials, Inc.
Priority date: 2009-11-18
Filing date: 2010-11-17
Publication date: 2011-05-26
Also published as: WO2011062943A3

Abstract

A method and apparatus for sputtering is provided. In one embodiment, a planar magnetron cathode is provided, comprised of a target and one or more magnet rails mounted to a cathode core. The planar magnetron cathode further comprises a backing plate mounted to the cathode core, the target being mounted to a mounting side of the backing plate. The planar magnetron cathode further comprises a cooling system mounted to a cooling side of the backing plate and a plurality of magnets mounted to the one or more magnet rails, the plurality of magnets having a substantially uniform magnetic field through at least a majority of the target. In one embodiment, the target comprises a primary target comprising a first material and a secondary target comprising the first material and a second material.

Description

PLANAR MAGNETRON SPUTTERING SOURCE PRODUCING HIGH TARGET UTILIZATION AND STABLE COATING UNIFORMITY OVER LIFETIME

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] Embodiments of the present invention generally relate to physical vapor deposition, and relates more particularly to a planar magnetron cathode. More specifically, the present invention is directed to methods and systems for providing magnetic fields within a magnetron sputtering device to achieve high target utilization and high performance coating uniformity. Other aspects of the present invention are directed to methods and systems relating to target configurations and cooling systems.

Description of the Related Art

[0002] Planar magnetrons typically utilize large magnets arranged in series across the length of the cathode. The distance between magnet interfaces, therefore, is significant. Also, the magnets are immersed in water from the cooling system, so they have to be waterproofed with a protective coating. The protective coating adds dimension to the magnet geometry, specifically to the interface gap between magnets.

[0003] Furthermore, because of their brittle nature, the magnets have to be protected from shattering, such as when the magnets are fastened in place in the cathode core using a clamping system. The magnets are high gauss, so it is necessary to have an aggressive means of keeping them in position. Typically, a rubberized boot is used to encase each magnet as an aid to prevent the clamping system from shattering the magnets.

[0004] Between the waterproofing protective coating and the rubberized boot, the distance between each magnet at the magnet interface is significant, e.g., the sum of 2 times the thickness of the waterproofing protective coating and 2 times the thickness of the rubberized boot. Such distance between magnets is significant, and is compounded by the distance between each magnet interface due to use of large magnets. The wide spacing between magnets and between interfaces of such magnets results in a sizeable deviation in magnetic field intensity (as measured through the target). The range and profile of the coating uniformity is greatly influenced by such deviations in the magnetic field. Thus, the large deviations in the magnetic field from the interfaces correspond to large deviations in coating uniformity.

[0005] However, a more uniform magnetic field is not possible with existing magnet arrangements. Accordingly, the coating produced with such a planar magnetron may lack a high level of uniformity desired for many applications. Planar magnetron cathodes have been unable to meet the demand for high target utilization combined with high uniformity and long, continuous runtimes. For example, operators have been unable to maintain a less than 4% uniformity rating over the lifetime of a target. A highly uniform magnetic field, resulting in a high level of coating uniformity while maintaining high target utilization, may be desirable.

[0006] Furthermore, in existing planar magnetrons, the target material sputtered from the turnaround target tile may contribute to the deposition onto the edge of the substrate. Furthermore, due to the geometries involved, with the sputtered area of a turnaround, with the source to substrate distance, with proximity of the turnaround to the edge of the substrate, etc., a thicker coating may be deposited at the edges of the substrate in a typical, desirable 100% load factor. This discrepancy in coating uniformity is typical, and there exists means by which it is accounted for, such as trim masks, gas trimming, magnetic field manipulations, etc. However, it may be undesirable to utilize such means. Additionally, due to the target erosion profiles of planar magnetron cathodes, operators have been unable to utilize thicker targets to increase continuous runtimes. Accordingly, a more uniform coating combined with high target utilization and increased runtimes may be desirable. [0007] Furthermore, long term reliability of planar magnetron cathodes has been less than desirable due to premature degaussing and/or degradation of the Nd_xFe_yB_z magnets, which were typically immersed in cooling water. The cooling systems of planar magnetron cathodes required water-to-vacuum seals, which also reduced continuous runtimes or significantly shortened the life-cycle of the cathode core. For example, some planar magnetron cathode cores suffered corrosion issues due to a water-to-vacuum seal leak that developed after 8 or 10 years. An improved cooling system may be desirable.

[0008] Accordingly, there is a need for an improved planar magnetron cathode that provides improved uniformity of deposition on a substrate with high target utilization, and decreased wear on the cathode core and undesirable degaussing of cathode magnets.

SUMMARY OF THE INVENTION

[0009] In one embodiment, a planar magnetron cathode is provided. The planar magnetron cathode comprises a target and one or more magnet rails mounted to a cathode core. The planar magnetron cathode further comprises a backing plate mounted to the cathode core, the target being mounted to a mounting side of the backing plate. The planar magnetron cathode further comprises a cooling system mounted to a cooling side of the backing plate and a plurality of magnets mounted to the one or more magnet rails, the plurality of magnets having a substantially uniform magnetic field through at least a majority of the target.

[0010] In another embodiment, a method of physical vapor deposition is provided. The method includes disposing in a deposition chamber a primary target comprised of a first material. The method further includes disposing in the deposition chamber a secondary target comprised of the first material and a second material, and disposing in the deposition chamber a substrate. The method further includes disposing proximate to the primary target and secondary target one or more magnet rails each having a plurality of magnets, providing an electrical charge to the primary target and secondary target to form a cathode, and igniting a plasma in the deposition chamber to sputter the first material from the primary target and the secondary target. The method further includes allowing the sputtered first material to deposit on the substrate.

[0011] In another embodiment, a device for physical vapor deposition is provided. The device comprises a primary target comprised of a first material and a secondary target comprised of a first material and a second material. The device further comprises a magnetic field source providing a magnetic field through the primary target and the secondary target. The device further comprises a substrate having an outer perimeter smaller than an outer perimeter of the primary target and the secondary target.

[0012] In another embodiment, a magnetron sputtering device is provided. The device comprises a plurality of magnets mounted in a rail assembly. The device further comprises a target, a substrate, and a chamber configured to house the substrate and the target. The device further comprises a backing plate having a mounting side for mounting the target and a cooling side. The device further comprises a closed loop cooling system mounted to the cooling side.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0014] Figure 1 illustrates a section view of a chamber with a substrate and cathode according to an embodiment of the present application. [0015] Figure 2 illustrates a two-part three dimensional view of a cathode according to an embodiment of the present application.

[0016] Figure 3 illustrates a magnet rail according to an embodiment of the present application.

[0017] Figure 4 illustrates a magnet rail according to an embodiment of the present application.

[0018] Figure 5 illustrates a magnet rail according to an embodiment of the present application.

[0019] Figure 6 illustrates a two-part three dimensional view of a cathode core and cooling system according to an embodiment of the present application.

[0020] Figure 7 illustrates a portion of a cooling system according to an embodiment of the present application.

[0021] Figure 8 illustrates a cooling system according to an alternative embodiment of the present application.

[0022] Figure 9 illustrates a section view of a cathode and substrate according to an embodiment of the present application.

[0023] Figure 10 illustrates a section view of a target according to an embodiment of the present application.

[0024] Figure 11 illustrates shunt and spacer patterns according to an embodiment of the present application.

[0025] Figure 12 illustrates shunt and spacer patterns according to an embodiment of the present application.

[0026] Figure 12a illustrates shunt and booster patterns according to an embodiment of the present application. [0027] Figure 13 illustrates shunt and spacer patterns according to an embodiment of the present application.

[0028] Figure 14 illustrates shunt and spacer patterns according to an embodiment of the present application.

[0029] Figure 15 illustrates a gauss map of a magnetic field according to an embodiment of the present application.

[0030] Figure 16 illustrates magnetic field uniformity and corresponding coating uniformity of a prior art magnet arrangement.

[0031] Figure 17 illustrates magnetic field uniformity and corresponding coating uniformity according to an embodiment of the present application.

DETAILED DESCRIPTION

[0032] The present invention relates to methods and devices for physical vapor deposition. More specifically, the present invention relates to a planar magnetron cathode that provides improved uniformity of deposition on a substrate, increased target utilization, and decreased wear on the cathode core and undesirable degaussing of cathode magnets.

[0033] In Figure 1 , a planar magnetron sputtering device is shown in cross-section. The planar magnetron sputtering device comprises a chamber 100, which includes a cathode 102, gas outlet 103, gas inlet 105 and substrate 130. Process gases may be supplied through gas inlet 105. The process gases may be evacuated through gas outlet 103 by a vacuum pump. The cathode 102 includes a core 104 and backing plate 118. The backing plate 1 18 is removably attached to core 104 via backing plate fastener 124. A target 126 is mounted to the backing plate 118 with mounting hardware, adhesive, or other suitable mounting mechanism. An electric charge may be applied to the cathode 102 and through target 126. [0034] Magnet rails 106 may be removably mounted into core 104 with clamp 114. Outer magnet stack 110 is mounted in outer magnetic rail 106a. Inner magnet stack 1 12 is mounted in inner magnet rail 106b. Each magnet stack 110 and 112 may be multiple magnets arranged vertically, as shown in Figures 3 and 4, or a single magnet.

[0035] Each magnet stack 1 10 and 1 12 may be glued into the magnet rails 106a and 106b, respectively. By gluing the magnets in place into the magnet rail, which is then removably mounted into the core 104 with clamp 114, the magnets do not require a rubberized boot or other protection to prevent shattering when clamped into place. Furthermore, as discussed further below with respect to Figures 6-8, the closed loop cooling circuit of some embodiments allows for mounting of the magnets without any waterproofing protective coating, because the magnets are not immersed in cooling water. Accordingly, the use of the magnet rails allows magnets of relatively short length to be used in the core 104 without the use of a rubberized boot or any waterproofing protective coating. Thus, the distance between each magnet, i.e., the width of the magnet interface, may be zero.

[0036] Uniformity of the deposited material on substrate 130 depends on, at least in part, uniformity of the magnetic field through the target 126 and the substrate 130. The use of long magnets results in widely spaced interfaces, and, therefore, significant deviations in the magnetic field. Thus, the range and profile of the coating uniformity on substrate 130 is influenced by the sizeable deviations in the magnetic field due to the distance between each magnet and between each magnet interface, as shown in Figure 16.

[0037] According to the teachings of the present application, the use of magnet rails allows smaller magnets to be arranged along the length of the rails and the cathode core. Without the need for waterproofing the magnets, the magnets can nest against one another. A planar cathode according to certain embodiments of the present application may utilize significantly shorter magnets made possible by the mounting of the magnets in magnet rails. Thus, some embodiments of the present application provide many magnet interfaces narrowly spaced along the rail and, therefore, the cathode. Accordingly, smaller magnets aligned together may provide a more uniform common magnetic field as compared to longer magnets aligned together. Also, the reduction in distance between any pair of magnets, i.e., the distance between each magnet interface, contributes to a more common magnetic field.

[0038] With relatively small differences in gauss due to the short distances between magnet interfaces as well as substantially zero width magnet interfaces, a more stable magnetic field is produced. The deviation from average of the magnetic field across the target may be significantly reduced. As shown in Figure 16 line 1602, a cathode with widely spaced magnet interfaces provides a magnetic field with an intensity that significantly deviates from average by ±3% or more. With narrow distances between magnet interfaces, and with substantially zero width magnet interfaces— made possible by the use of magnet rails according to the teachings of the present application— the magnetic field may be substantially uniform. In some embodiments of the present application, the magnetic field intensity from the magnets in the magnet rails may have a deviation from average of less than ±1 %, as shown in Figure 17, line 1702.

[0039] As noted, coating uniformity is highly influenced by the uniformity of the magnetic field. Deviations in coating uniformity may correspond to deviations in the magnetic field. Thus, a cathode with wide distances between magnet interfaces and with wide magnet interfaces provides a coating uniformity that may significantly deviate from average by ±4% or more, as shown in Figure 16, line 1604. With narrowly spaced interfaces made possible by the use of magnet rails according to the teachings of the present application, the coating may be substantially uniform.

[0040] The more uniform magnetic field across the target provides for a more uniform deposition of material on substrate 130. The design of the magnet rail system, according to embodiments of the present application, minimizes or even substantially eliminates deviations in the magnetic field, resulting in a high degree of coating uniformity while maintaining high target utilization. In some embodiments of the present application, the coating uniformity produced by a planar magnetron sputtering device utilizing embodiments of the present application may have a deviation from average of less than ±1%, as shown in Figure 17, line 1704. Coating uniformity may be substantially uniform even after extended runs. For example, after more than approximately 7,000 kW-hrs with silver targets, a coating uniformity deviation from average of less than ±1 % can be achieved.

[0041] The magnet stacks 110 and 112 may have similar magnetic profiles. The magnet stacks may be glued into their mounted positions in the magnet rail. The configuration of outer magnet stack 110 may be substantially similar to the configuration of inner magnet stack 1 12. In some embodiments, the configuration of outer magnet stack 110 may be different than the configuration of inner magnet stack 112, depending on specific characteristics of the magnets used and the magnetic field desired. In some embodiments, outer magnet rails 106a may be shorter than inner magnet rails 106b, to provide ease of assembly. In other embodiments, outer magnet rails 106a and inner magnet rails 106b may be the same length, to provide interchangeability. In some embodiments, the outer magnet rails 106a and inner magnet rails 106b may be interchangeable between planar magnetrons. The magnet rails 106 may be one-piece aluminum rails. The magnet rails 106 may be compatible with existing planar magnetron sputtering devices. For example, an existing planar magnetron sputtering device may be retrofitted with the magnet rails 106 of the present application to improve uniformity and/or target utilization. According to some embodiments of the present application, there may be two outer magnet rails 106a and two inner magnet rails 106b. Figure 3, discussed further below, illustrates a cross-section of magnet rail 106.

[0042] Clamps 1 14 attach to core 104 via clamp fasteners 115. Shunts 116 may be provided between magnet rails 106 and clamps 114. A variety of shunt configurations may be utilized, depending on desired characteristics of the magnetic field through the target 126, as discussed below with respect to Figures 14-17. Spacers 117 may also be placed between magnet rails 106 and clamps 114, as necessary depending on the configurations of shunts 116, to provide for a secure fit between magnet rails 106 and clamps 114.

[0043] Plasma 128 is ignited in chamber 100. The high energy plasma particles sputter the target 126. The sputtered material from target 126 is then deposited on substrate 130. The backing plate 118 includes a cooling system 122, which is discussed in further detail below, with respect to Figures 6-8. The cooling system may include cooling conduits 120.

[0044] Figure 2 is a perspective view of cathode 102. In view A, only the core 104 is shown. In view B, side magnet rails 106a and 106b are mounted in the core 04, as described above. Inner turnaround magnet rail 107 and outer turnaround magnet 108 are also mounted in the core 104. As can be seen in Figure 2, shunts 116 may be placed in a desired configuration between the magnet rails and the clamps 114. Spacers 117 may also be used, as necessary, to provide for a secure fit between magnet rails 106 and clamps 114.

[0045] Figure 3 illustrates a cross-section, in perspective, of magnet rail 106. Inner magnet stack 12 is mounted within inner magnet rail 106b. Although not shown, outer magnet stack 110 is similarly mounted within outer magnet rail 106a. The magnet stack 110 or 112 may be comprised of one or more vertically stacked magnets, depending on desired characteristics of the magnetic field through the target 126. For example, the magnet stacks 10 and 112 may be two stacked magnets.

[0046] Figure 4 illustrates a cross-section, in perspective, of outer turnaround magnet rail 108. Outer turnaround magnet stack 111 is mounted within outer turnaround magnet rail 108. The magnet stack 111 may be comprised of one or more magnets, depending on desired characteristics of the magnetic field through the target 126. For example, in some embodiments, the magnet stack 111 may be comprised of three stacked magnets. The outer turnaround magnet rail may be a single aluminum rail. According to some embodiments, outer turnaround magnet stack forms a square/rectangular shape. In other embodiments, a round or curved shape may be used.

[0047] Figure 5 illustrates a cross-section, in perspective, of inner turnaround magnet rail 107. Inner turnaround magnet 113 is mounted within inner turnaround magnet rail 107. Inner turnaround magnet 113 may be a single magnet or a magnet stack. According to some embodiments, inner turnaround magnet 113 generally forms a semi-circle. In other embodiments, other round/curved shapes or square/rectangular shapes may be used.

[0048] Some embodiments of the present application provide for a closed loop cooling system. Figures 6-8 illustrate certain embodiments of the cooling system 122 mounted to the backing plate 118. Figure 6 depicts the backing plate 1 18 in see-through detail and the cooling system 122. In Figure 6, view A and Figure 7, coolant supply conduit 119a and coolant o-rings 121 are shown disassembled for detail. In Figure 6, view B, the backing plate 118 (in see-through detail) is shown mounted to core 104. Coolant is supplied to the cooling system 122 through coolant supply conduit 119a, which is fastened to coolant inlet pan 123a. Coolant o-rings 121 ensure a tight seal between coolant inlet pan 123a and coolant supply conduit 119a. From coolant inlet pan 123a, coolant flows through each cooling conduit 120 to coolant outlet pan 123b and out through coolant supply conduit 119b. In this manner, the cooling system 122 removes heat, as necessary, from the planar magnetron cathode 102 with use of a closed loop cooling circuit.

[0049] Figure 8 illustrates an alternative embodiment of the cooling system 122 mounted to the backing plate 118. Coolant flows through coolant supply conduit 119a and into continuous coolant pan 123. After flowing through continuous coolant pan 123, the coolant flows out through coolant supply conduit 119b. Thus, coolant may flow across the backing plate 18 through cooling conduit 120 (as shown in Figures 6 and 7), or through a continuous coolant pan 123 (as shown in Figure 8), or through any closed circuit conduit suitable for coolant flow and heat transfer. In some embodiments, the coolant used may be water, although other suitable coolants may be used in the cooling system 122. The cooling system 122 may provide for coolant flow of around 20 to 36 gallons per minute; although embodiments may utilize a higher or lower coolant flow rate.

[0050] During a test run of a planar magnetron sputtering device at various power settings, a coolant (water) flow of approximately 20 gallons per minute was utilized in an embodiment of the cooling system 22. The water temperature at the various power settings is shown in Table 1 :

During the 8 hour test run, the temperature of the core assembly was maintained below 116° C (241° F). In some embodiments of the present application, the various magnets— e.g., magnet stacks 111 , 112, and 113— may be Nd_xFe_yB_z magnets, although magnets made of other materials are not excluded from embodiments of the present application. It is known that Nd_xFe_yB_z magnets are adversely affected by temperatures above 180° C. Such degradation of the Nd_xFe_yB_z magnets may influence magnetic performance and uniformity. The closed loop coolant circuit on the backing plate allows the Nd_xFe_yB_z magnets to operate at powers up to 70 kW during testing without coming into contact with water. The closed circuit design eliminates the possibility of coolant-to-vacuum seal leaks, which may be crucial in ultra sensitive layers like silver. Accordingly, the cooling system 122 provides the necessary cooling for the cathode 102 while providing the benefits of a closed loop coolant circuit.

[0051] Coolant flows through cooling system 122 in a closed loop. Notably, in the foregoing arrangements of the cooling system 122, there are no coolant-to-vacuum seals. Thus, according to certain embodiments of the present application, the elimination of coolant-to-vacuum seals reduces downtime required for maintenance and continuous runtime can be increased. The backing plate 118 with cooling system 122 may be compatible with existing planar magnetron sputtering devices. For example, an existing planar magnetron sputtering device may be retrofitted with the backing plate 118 and cooling system 122 of the present application. In such a case, coolant-to-vacuum seals and/or coolant connections may need to be removed from the cathode core of the existing planar magnetron sputtering device.

[0052] Some embodiments of the present application provide for a first target and second target. Figure 9 illustrates an aspect of the present application. Target 126 is mounted to planar magnetron cathode 102. Sputtered material from target 126 is deposited on substrate 130. In some embodiments of the present invention, target 126 may include a side target 126a made of a first material and turnaround targets 126b made of a first material and a second material, as shown in Figure 9. For example, the first material may be silver and the second material may be titanium. The turnaround targets 126b may correspond to turnaround portions of the cathode 102. The side target 126a may be a primary target and the turnaround target 126b may be a secondary target.

[0053] Target life may be greatly influenced by the wear at the turnarounds. For example, turnaround target tiles typically wear through before the others on a planar magnetron. Accordingly, placing a slower sputtering material, such as titanium, at the turnaround of a silver cathode, for example, may retard the erosion process at the turnaround relative to the silver tiles and in turn, increase the overall target utilization capabilities of the silver tiles.

[0054] It may be desirable to have a high gauss at the turnaround. For example, a high gauss at the turnaround may greatly reduce or eliminate the "cross-corner" effect, which is an erosion pattern that occurs at two specific spots in the racetrack coming out of the turnarounds. The cross-corner effect may also limit the target life by prematurely eroding through the target at these select spots. By reducing or eliminating the cross corner effect, it is possible for coating uniformities to be improved as well as target utilization to be increased. According to some embodiments of the present application, use of a turnaround target having two materials may allow use of high gauss magnetic fields. In some embodiments, utilizing high gauss magnetic fields with a turnaround target having two materials may reduce a cross-corner effect, improve uniformity, and/or result in higher target utilization.

[0055] However, if the rate of the second material in the new turnaround target tile is significantly slower than the primary target material— titanium and silver, respectively, for example— an undesirable condition may occur as the target tiles wear through at the different rates. For example, a step may occur at the entrance of the turnaround as viewed by the electrons, which will cause arcing, target melts, etc. Accordingly, in some embodiments, the rate of the dissimilar turnaround material may ideally be about ½ that of the primary target tiles if the primary target and turnaround target tiles are of equal thickness. Since different materials and processes sputter at different rates, a complex matrix could be composed setting forth preferred secondary materials that could be married up with the primary target materials. Therefore, a suitable turnaround tile may be utilized depending on the desired application.

[0056] In an embodiment, two turnaround tiles of varying thicknesses are stacked to form one turnaround tile at each end of the planar magnetron cathode. One of these tiles may be the same material as the side tiles while the other tile may be the slower rate material. For example, if the side tiles are silver, one of the turnaround tiles may be silver and the other turnaround tiles may be titanium. The thickness of the slower rate target tile may be varied depending upon the rate of the primary target material. For example, a silver target might use a titanium turnaround tile of x/6 thickness, where x = target tile thickness of silver. The slower rate target tile (titanium) would be positioned underneath the silver tile. In the case where a 1.5" target tile thickness is being used, the titanium turnaround tiles would be ¼" thick and placed under the 1 ¼" thick silver turnaround tiles. [0057] Thus, according to some embodiments, longer runtimes between target change-out may be achieved by using slower sputtering material in turnaround targets. Similarly, longer runtimes between target change-out may be achieved by using thicker targets. For example, 1.375 inch thick silver targets were tested in extended operation coating runs for approximately 4,300 kW-hrs. This is the equivalent of running for 22 days at 10 kW, which may be approximately 50% longer than previous cathode technology. In Figure 10, target erosion profiles 1002, 1004 and 1006 are indicated for the silver targets at 0 kW-hrs, 2,100 kW-hrs and 4,000 kW-hrs respectively. Based on the Figure 10 erosion profiles, a 1.375 inch thick silver target could be utilized for approximately 5,300 kW-hrs before a change-out would be required. Thus, according to some embodiments, runtimes between approximately 5,000 and 6,000 kW-hrs may be achieved before a target change-out may be required. Similarly, targets as thick as 1.625 inches may be used for approximately 6,700 kW-hrs or even longer before target change-out may be required. Thus, according to some embodiments, runtimes between approximately 6,000 and 7,000 kW-hrs may be achieved before a target change- out may be required.

[0058] According to some embodiments of the present application, by increasing the length of the cathode assembly relative to the substrate, the turnaround portion of the target can be distanced from the edge of the substrate. In other words, the turnaround portion of the sputtering target assembly may extend beyond the width of the substrate it is designed to sputter coatings onto. The contribution to the coating made by the turnaround may be reduced significantly or eliminated. This will decrease significantly or eliminate fully the influence of the turnaround on coating homogeneity/uniformity on the substrate. As such, this allows for the choosing of different target materials to be used at the turnaround locations.

[0059] As noted above, certain embodiments of the present application provide for a more uniform magnetic field which may result in high coating uniformity. Nonetheless, it may be desirable to further tune the magnetic field to suit a particular application. For example, different target sizes may require modifications to the magnetic field through use of magnetic shunts or magnetic boosts. A shunt may be located vertically in the core 104 to locally reduce the magnetic field. Similarly, a boost located horizontally in the cathode core to locally boost the magnetic field. Shunts and/or boosts may be comprised of an appropriate shunting material, such as Ni 200, and may be of a desired thickness. For example, in an embodiment of the present application, Ni 200 shunts and/or Ni 200 boosts with thickness of 0.030 inches and 0.060 inches may be used. The length, thickness and/or location of the shunts and/or boosts may vary, depending on the desired application and/or effect.

[0060] Figures 11-14 illustrate shunt patterns that may be used according to the target size. In Figure 11 , an arrangement of 0.060 inch shunts 116a, 0.030 inch shunts 116b, and spacers 1 17 which may be suitable for use with 1 inch targets is shown. In Figure 12, an arrangement of 0.060 inch shunts 116a, 0.060 inch shunts 116b, and spacers 1 17 which may be suitable for use with 1.25 inch targets is shown. In Figure 12a, an arrangement of 0.060 inch shunts 116a and boost 116c is shown. In Figure 13, an arrangement of 0.060 inch shunts 116a and 0.030 inch shunts 116b which may be suitable for use with 1.375 inch targets is shown. In Figure 14, an arrangement of 0.030 inch shunts 116a which may be suitable for use with 1.5 inch targets is shown. Thus, according to embodiments of the present application, shunts and boosts may be used to fine-tune the magnetic field to desired characteristics.

[0061] Figure 15 illustrates a gauss-map of an exemplary magnetic field due to magnet stacks 111 , 112 and 113 according to certain embodiments of the present application. As can be seen in Figure 15, a high uniformity magnetic field through at least a majority of the target results from the novel features of the present application.

[0062] Accordingly, embodiments of the present application provide for an improved planar magnetron cathode with improved uniformity, target utilization, and cooling system, and methods for use thereof. [0063] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

A planar magnetron cathode comprising:

a cathode core;

a backing plate mounted to the cathode core, the backing plate having a mounting side configured for mounting a target and a cooling side configured for mounting a cooling system;

one or more magnet rails mounted to the cathode core; and

a plurality of magnets mounted to the one or more magnet rails.

The planar magnetron cathode of claim 1 wherein the plurality of magnets comprises at least a first magnet and a second magnet linearly mounted to the one or more magnet rails, wherein the distance between the first magnet and the second magnet is substantially zero.

The planar magnetron cathode of claim 1 wherein the one or more magnet rails comprises at least a first magnet rail and a second magnet rail and wherein the first magnet rail and the second magnet rail are interchangeable.

The planar magnetron cathode of claim 1 wherein the plurality of magnets mounted to the one or more rail magnets forms an inner continuous loop and an outer continuous loop.

The planar magnetron cathode of claim 1 wherein the magnetic field is configured to have a variation in intensity of less than ±1% along a length of the target.

The planar magnetron cathode of claim 1 wherein the cathode core is configured for mounting at least one of a shunt or a boost for tuning the magnetic field.

7. The planar magnetron cathode of claim 1 wherein the magnetic field is configured to produce a coating uniformity on the substrate having a deviation from average of less than ±1%.

8. The planar magnetron cathode of claim 7 wherein the coating uniformity on the substrate has a deviation from average of less than ±1% after approximately 7,000 kW-hrs with the same target.

9. A system for cooling a planar magnetron cathode having a cathode core and a plurality of magnets mounted to the cathode core, the cooling system comprising:

a backing plate configured for mounting to the cathode core, the backing plate having a mounting side configured for mounting a target and a cooling side; and

a closed loop cooling system mounted to the cooling side, the closed loop cooling system comprising:

an inlet pan,

an outlet pan, and

at least one coolant conduit configured to convey a coolant from the inlet pan to the outlet pan,

wherein the closed loop cooling system is configured for circulation of the coolant without the coolant contacting the plurality of magnets.

10. The system of claim 9 wherein the closed circuit cooling system is further configured for circulation of the coolant without a coolant-to-vacuum seal.

11. The system of claim 9 wherein the closed loop cooling system is further configured to maintain a temperature of the plurality of magnets below 180°C.

12. The system of claim 9 wherein the inlet pan, the outlet pan and the at least one coolant conduit form a continuous coolant pan.

13. A target system for physical vapor deposition on a substrate, the target system comprising:

a primary target comprised of a first material; and

a secondary target comprised of the first material and a second material;

wherein

the primary target and the secondary target are configured for mounting to a backing plate, and

the first material has a higher sputtering rate than the second material.

14. The target system of claim 13 wherein the target system is configured to allow the first material to deposit on the substrate when the first material is sputtered.

15. The target system of claim 14 wherein the target system is configured to substantially prevent the second material from depositing on the substrate.