Patent Publication Number: US-2022213590-A1

Title: Methods and apparatus for processing a substrate using improved shield configurations

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application and claims priority to and the benefit of International Patent Application Serial No. PCT/CN2021/070332, filed on Jan. 5, 2021, the entire contents of which is incorporated herein by reference. 
    
    
     FIELD 
     Embodiments of the present disclosure generally relate to a methods and apparatus for processing a substrate, and more particularly, to methods and apparatus for processing a substrate using improved shield configurations. 
     BACKGROUND 
     Magnitude of target self-bias can impact the sputtering rates of a target and an anode (e.g. shields, wafer, etc.) material. Commonly, higher negative self-bias on targets is obtained by using extremely wide body chambers, thus increasing the anode area. However, such an approach can lead to increased footprint of an PVD chamber. 
     SUMMARY 
     Methods and apparatus for processing a substrate using improved shield configurations are provided herein. In some embodiments, a process kit for use in a physical vapor deposition chamber includes a shield comprising an inner wall with an innermost diameter configured to surround a target when disposed in the physical vapor deposition chamber, wherein a ratio of a surface area of the shield to a planar area of the inner diameter is about 3 to about 10. 
     In accordance with at least some embodiments, a substrate processing apparatus includes a chamber body having a substrate support disposed therein, a target coupled to the chamber body opposite the substrate support, an RF power source to form a plasma within the chamber body, and a shield comprising an inner wall with an innermost diameter configured to surround the target when disposed in a physical vapor deposition chamber, wherein a ratio of a surface area of the shield to a planar area of the inner diameter is about 3 to about 10. 
     In accordance with at least some embodiments, a process kit for use in a physical vapor deposition chamber includes a shield comprising an inner wall with an innermost diameter configured to surround a target when disposed in the physical vapor deposition chamber comprising, the inner wall comprising one of a plurality of alternating bends that extend in generally 90° increments from top, down, outwards, down, inwards, and down forming an entire generally C shape between alternating bends or a plurality of spaced-apart concentric walls extending upward from a bottom of the shield to define a plurality of vertical wells, wherein a ratio of a surface area of the shield to a planar area of the inner diameter is about 3 to about 10. 
     Other and further embodiments of the present disclosure are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  is a schematic cross-sectional view of a process chamber in accordance with some embodiments of the present disclosure. 
         FIG. 2  is a sectional view of a shield and surrounding structure in accordance with some embodiments of the present disclosure. 
         FIG. 3  is a sectional view of a shield and surrounding structure in accordance with some embodiments of the present disclosure. 
         FIG. 4  is an enlarged view of the indicated area of detail of  FIG. 3  in accordance with some embodiments of the present disclosure. 
         FIG. 5  is a sectional view of a shield and surrounding structure in accordance with some embodiments of the present disclosure. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     Methods and apparatus for improved physical vapor deposition (PVD) processing equipment are provided herein. The PVD processes may advantageously be high density plasma assisted PVD processes, such as described below. In at least some embodiments of the present disclosure, the improved methods and apparatus provide a grounded shield for a PVD processing apparatus that may advantageously lower the potential difference to the grounded shield while maintaining target to substrate spacing, thereby facilitating PVD processing with reduced or eliminated re-sputtering of the grounded shield. For example, a shield can include an inner wall with an innermost diameter configured to surround a target when disposed in the PVD chamber. A ratio of a surface area of the shield to a planar area of the inner diameter is about 3 to about 10. 
       FIG. 1  is a schematic cross-sectional view of a process chamber  100  (e.g., a substrate processing apparatus) in accordance with some embodiments of the present disclosure. The specific configuration of the PVD chamber is illustrative and PVD chambers having other configurations may also benefit from modification in accordance with the teachings provided herein. Examples of suitable PVD chambers include any of the line of PVD processing chambers, commercially available from Applied Materials, Inc., of Santa Clara, Calif. Other processing chambers from Applied Materials, Inc. or other manufactures may also benefit from the inventive apparatus disclosed herein. 
     In some embodiments of the present disclosure, the process chamber  100  includes a chamber lid  101  disposed atop a chamber body  104  and removable from the chamber body  104 . The chamber lid  101  generally includes a target assembly  102  and a grounding assembly  103 . The chamber body  104  contains a substrate support  106  for receiving a substrate  108  thereon. The substrate support  106  is configured to support a substrate such that a center of the substrate is aligned with a central axis  186  of the process chamber  100 . The substrate support  106  may be located within a lower grounded enclosure wall  110 , which may be a wall of the chamber body  104 . The lower grounded enclosure wall  110  may be electrically coupled to the grounding assembly  103  of the chamber lid  101  such that an RF return path is provided to an RF power source  182  disposed above the chamber lid  101 . Alternatively, other RF return paths are possible, such as those that travel from the substrate support  106  via a process kit shield (e.g., a grounded shield (e.g., anode) and ultimately back to the grounding assembly  103  of the chamber lid  101 . The RF power source  182  may provide RF energy to the target assembly  102  as discussed below. 
     The substrate support  106  has a material-receiving surface facing a principal surface of a target  114  (e.g., a cathode opposite the substrate support) and supports the substrate  108  to be sputter coated with material ejected from the target  114  in planar position opposite to the principal surface of the target  114 . The substrate support  106  may include a dielectric member  105  having a substrate processing surface  109  for supporting the substrate  108  thereon. In some embodiments, the substrate support  106  may include one or more conductive members  107  disposed below the dielectric member  105 . For example, the dielectric member  105  and the one or more conductive members  107  may be part of an electrostatic chuck, RF electrode, or the like which may be used to provide chucking or RF power to the substrate support  106 . 
     The substrate support  106  may support the substrate  108  in a first volume  120  of the chamber body  104 . The first volume  120  is a portion of the inner volume of the chamber body  104  that is used for processing the substrate  108  and may be separated from the remainder of the inner volume (e.g., a non-processing volume) during processing of the substrate  108  (for example, via a shield  138 ). The first volume  120  is defined as the region above the substrate support  106  during processing (for example, between the target  114  and the substrate support  106  when in a processing position). 
     In some embodiments, the substrate support  106  may be vertically movable to allow the substrate  108  to be transferred onto the substrate support  106  through an opening (such as a slit valve, not shown) in the lower portion of the chamber body  104  and thereafter raised to a processing position. A bellows  122  connected to a bottom chamber wall  124  may be provided to maintain a separation of the inner volume of the chamber body  104  from the atmosphere outside of the chamber body  104 . One or more gases may be supplied from a gas source  126  through a mass flow controller  128  into the lower part of the chamber body  104 . An exhaust port  130  may be provided and coupled to a pump (not shown) via a valve  132  for exhausting the interior of the chamber body  104  and to facilitate maintaining a desired pressure inside the chamber body  104 . 
     An RF bias power source  134  may be coupled to the substrate support  106  in order to induce a negative DC bias on the substrate  108 . In addition, in some embodiments, a negative DC self-bias may form on the substrate  108  during processing. In some embodiments, RF energy supplied by the RF bias power source  134  may range in frequency from about 2 MHz to about 60 MHz, for example, non-limiting frequencies such as 2 MHz, 13.56 MHz, or 60 MHz can be used. In other applications, the substrate support  106  may be grounded or left electrically floating. Alternatively or additionally, a capacitance tuner  136  may be coupled to the substrate support  106  for adjusting voltage on the substrate  108  for applications where RF bias power is not be desired. 
     The shield  138  (e.g., a grounded process kit shield) can be made of at least one of an aluminum alloy or stainless steel and surrounds the processing, or first volume, of the chamber body  104  to protect other chamber components from damage and/or contamination from processing. In some embodiments, the shield  138  may be coupled to a ledge  140  of an upper grounded enclosure wall  116  of the chamber body  104 . In other embodiments, and as illustrated in  FIG. 1 , the shield  138  may be coupled to the chamber lid  101 , for example via a retaining ring (not shown). 
     The shield  138  comprises an inner wall  143  disposed between the target  114  and the substrate support  106 . In at least some embodiments, the inner wall  143  is provided with an innermost diameter configured to surround the target  114  when disposed in the process chamber  100 . In at least some embodiments, a ratio of a surface area of the shield  138  to a planar area of the inner diameter is about 3 to about 10, as will be described in greater detail below. The height of the shield  138  depends upon the substrate distances  185  between the target  114  and the substrate  108 . The substrate distances  185  between the target  114  and the substrate  108 , and correspondingly, the height of the shield  138 , is scaled based on the diameter of the substrate  108 . In some embodiments, the ratio of the diameter of the target  114  to the diameter of the substrate is about 1.4. For example, a process chamber for processing a 300 mm substrate may have a target  114  having a diameter of about 419 mm or, in some embodiments, a process chamber for processing a 450 mm substrate may have a target  114  having a diameter of about 625 mm. In some embodiments, the ratio of the diameter of the target  114  to the height of the shield  138  is about 4.1 to about 4.3, or in some embodiments, about 4.2. For example, in some embodiments of a process chamber for processing a 300 mm substrate, the target  114  may have a diameter of about 419 mm and the shield  138  may have a height of about 100 mm or, in some embodiments of a process chamber for processing a 450 mm substrate, the target  114  may have a diameter of about 625 mm and the shield  138  may have a height of about 150 mm. Other diameters and heights may also be used to provide the desired ratio. In process chambers having the ratios described above the substrate distances  185  between the target  114  and the substrate  108  is about 50.8 mm to about 152.4 mm for a 300 mm substrate or about 101.6 mm to about 203.2 mm for a 450 mm substrate. A process chamber having the above configurations is referred to herein as a “short throw” process chamber. 
     The short throw process chamber advantageously increases the deposition rate over process chambers having longer target to substrate distances  185 . For example, for some processes, conventional process chambers having longer target to substrate distances  185  provide a deposition rate of about 1 to about 2 angstroms/second. In comparison, for similar processes in a short throw process chamber, a deposition rate of about 5 to about 10 angstroms/second can be obtained while maintaining high ionization levels. In some embodiments, a process chamber in accordance with embodiments of the present disclosure may provide a deposition rate of about 10 angstroms/second. High ionization levels at such short spacing can be obtained by providing a high pressure, for example, about  60  millitorr to about 140 millitorr, and a very high driving frequency, for example, from about 27 MHz to about 162 MHz, for example such as at about such readily commercially available frequencies as 27.12, 40.68, 60, 81.36, 100, 122, or 162.72 MHz. 
     Additionally, electrons have higher mobility than ions, and during their respective half cycles, both the electrodes (e.g., the cathode or powered electrode and the anode or grounded electrode) will quickly acquire electrons until the electrodes can no longer attract more of the electrons due to repulsion from accumulated electrons. During the negative half-cycle, both the electrodes will attract positive ions, however due to the lower mobility of ions, the electrodes will not neutralise all the electrons and will acquire a net negative bias relative to plasma. 
     The inventors have found that if the area of both the electrodes (cathode (target) and anode (shield, wafer, dep ring, cover ring, etc.)) is comparable, then the ions created in the plasma will be attracted towards both the electrodes in equal proportions during their respective negative half-cycles, which, in turn, would lead to sputtering of material from both the electrodes in comparable proportions. However, in RF sputter-deposition, the area of the target is usually preferred to be smaller (e.g., helps to enable more deposition and less etching on the anode side) than the area of the anode (shield, wafer, dep ring, cover ring, etc.), which, in turn, can lead to a higher magnitude of negative bias and, thus higher electric field to accelerate the ions towards the target. Accordingly, depending on an area of the target (cathode) relative to the shield (anode), there will either be deposition from the target (sputter-deposition) or there will be etching (re-sputtering) of the anode (wafer, shields, dep ring, etc.). 
     Re-sputtering of the shield  138  causes undesirable contamination within the process chamber  100 . The re-sputtering of the shield  138  is a result of the high voltage on the shield  138 . The amount of voltage that appears on the target  114  (e.g., the cathode or powered electrode) and the grounded shield  138  (e.g., the anode or grounded electrode) is dependent on the ratio of the surface area of the shield  138  to the surface area of the target  114 , as a greater voltage appears on the smaller electrode. Sometimes the surface area of the target  114  can be larger than the surface area of the shield  138  resulting in a greater voltage upon the shield  138 , and in turn, resulting in the undesired re-sputtering of the shield  138 . For example, in some embodiments of a process chamber for processing a 300 mm substrate, the target may have a diameter of about 419 mm with a corresponding surface area of about 138 mm 2  and the shield  138  may have a height of about 100 mm with a corresponding surface area of about 132 mm 2  or, in some embodiments of a process chamber for processing a 450 mm substrate, the target may have a diameter of about 625 mm with a corresponding surface area of about 307 mm 2  and the shield  138  may have a height of about 150 mm with a corresponding surface area of about 295 mm 2 . The inventors have observed that in some embodiments of process chambers where the ratio of the surface area of the shield  138  to the surface area of the target  114  is less than 1, a greater voltage is incurred upon the shield  138 , which in turn, results in the undesired re-sputtering of the shield  138 . Thus, in order to advantageously minimize or prevent the re-sputtering of the shield  138 , the inventors have observed that the surface area of the shield  138  needs to be greater than the surface area of the target  114 . For example, the inventors have observed that a ratio of the surface area of the shield  138  to the surface area of the target  114  of about 3 to about 10 advantageously minimizes or prevents the re-sputtering of the shield  138 . 
     Additionally, the inventors have observed that a ratio of the surface area of the shield  138  to the surface area of the target  114  of about 3 to about 10 advantageously provides a relatively high negative self-biasing at the target  114 . For example, the relatively high negative self-biasing at the target  114  attracts more positive plasma ions (e.g., argon ions) toward the target  114  during operation, which, in turn, increases target sputtering and decreases re-sputtering (e.g., etching) of the shield  138 , a deposition ring (not shown), the substrate  108 , or other component. 
     However, the surface area of the shield  138  cannot be increased by simply increasing the height of the shield  138  due to the desired ratio of the diameter of the target  114  to the height of the shield  138 , as discussed above. The inventors have observed that, in some embodiments of a process chamber having the processing conditions discussed above (e.g., process pressures and RF frequencies used), the ratio of the surface area of the shield  138  to the height of the shield  138  must be about 2 to about 3 to advantageously minimize or prevent the re-sputtering of the shield  138 . Furthermore, the diameter of the shield  138  cannot be increased sufficiently to increase the surface area of the shield  138  to prevent re-sputtering of the shield  138  due to physical constraint in the size of the process chamber. For example, an increase in the diameter of the shield  138  of 25.4 mm results in a surface area increase of only 6%, which is insufficient to prevent the re-sputtering of the shield  138 . 
     Accordingly, the larger area of anode is achieved by providing a shield having a wavy configuration (with or without fins), thus providing a geometry that allows for deposition of highly insulating dielectric targets by increasing the negative self-bias on the target. Thus, in some embodiments, as depicted in  FIG. 2 , in order to obtain the desired ratio of the surface area of a shield to the surface area of a target, a shield  200 , which is configured for use with the process chamber  100 , includes an inner wall  203  with an innermost diameter D 1  configured to surround a target when disposed in the physical vapor deposition chamber. For example, the innermost diameter D 1  can be greater than a diameter of a target. In at least some embodiments, a ratio of a surface area of the shield to a planar area of the inner diameter is about 3 to about 10 (e.g., anode to cathode ratio). 
     For example, in at least some embodiments the inner wall  203  comprises a plurality of alternating bends  208  that extend in generally 90° increments from top, down, outwards, down, inwards, and down, thus forming an entire generally C shape between alternating bends  208 . The plurality of alternating bends  208  form a vertical square wave with rounded transitions when viewed along a cross-section of two consecutive bends. In at least some embodiments, the plurality of alternating bends  208  are symmetrical with each other. That is, each of the entire generally C shape have identical dimensions. Alternatively, in at least some embodiments, the plurality of alternating bends  208  are asymmetrical with each other. That is, each of the entire generally C shape have different dimensions, e.g., an inwardly facing C shape can extend further inward than an outwardly facing C shape extends outward, or vice versa. 
     The inner wall  203  includes a bottom area  210 . The bottom area  210  can contribute to an overall area of the shield  200 . For example, the bottom area  210  can add about 50 in 2  to the overall area of the shield  200 . In at least some embodiments, a plurality of concentric vertical fins  300  are supported on or near the bottom area  210  ( FIGS. 3 and 4 ). The plurality of concentric vertical fins  300  are connected to each other so that consecutive concentric vertical fins form a generally shape when viewed along a cross-section of two consecutive concentric vertical fins ( FIG. 4 ). The plurality of concentric vertical fins  300  are configured to increase an overall area of the shield  200 . In at least some embodiments, the plurality of concentric vertical fins  300  are spaced-apart from each other at about 0.15 inches to about 0.2 inches, and in at least some embodiments, the plurality of concentric vertical fins  300  are spaced-apart from each other at about 0.175 inches. 
     The plurality of concentric vertical fins  300  can have various dimensions, e.g., depending on a desired overall area of a shield. For example, the plurality of concentric vertical fins  300  can have a height that is about equal to an entire C shape between alternating bends (e.g., 0.50 inches to about 1.10 inches), as shown in  FIG. 4 . In at least some embodiments, for example, each of the plurality of concentric vertical fins  300  can have a height of about 0.70 inches to about 1.10 inches. For example, an inner most concentric vertical fin  302  can have an concave portion  314  (e.g., a portion that is closer to the substrate processing surface  109 ) having a height of about 1.05 inches and a convex portion  316  (e.g., a portion that is farther from the substrate processing surface  109 ) having a height of about 1.00 inch. The height of the concave portion  314  is slightly greater than the height of the convex portion  316  because the concave portion  314  defines an exterior of a vertical fin and the convex portion  316  defines an interior of the vertical fin. The inner portion  316  is disposed opposite to an outer portion, which also has a height of about 1.00 inch, of a concentric vertical fin  304 , thus forming a well  318  having a depth of about 1.00 inch (e.g., a depth of a well is defined by the concave/convex portions that define the well). The concave/convex portions of the remaining concentric vertical fins can form similar wells therebetween. For example, a convex portion of the concentric vertical fin  304  is disposed opposite a concave portion of a concentric vertical fin  306  each having a height of about 1.00 inch can also form a well  318  having a depth of about 1.00 inch. 
     In embodiments, the wells formed between each of the concentric vertical fins  300  can have the same depth or a different depth. For example, in at least some embodiments, a convex portion of a concentric vertical fin  306  disposed opposite a concave outer portion of a concentric vertical fin  308  can each have a height of about 0.70 inches, thus forming a well  318  (e.g., a middle well) having a depth of about 0.70 inches. In the illustrated embodiments, a convex portion of a concentric vertical fin  310  and a concave portion of the concentric vertical fin  308  can form a well similar to the well formed between the convex portion  316  and the concave portion of the concentric vertical fin  304 . Additionally, a concave portion of an outermost concentric vertical fin  312  can form a well between the convex portion of the concentric vertical fin  310 , similar to the well formed between the convex portion  316  and the concave portion of the concentric vertical fin  304 . 
     Each of the plurality of concentric vertical fins  300  can have a thickness of about 0.04 inches to about 0.06 inches, and each of the plurality of concentric vertical fins  300  can have the same or different thickness. For example, in at least some embodiments, the inner most concentric vertical fin  302  and the outermost concentric vertical fin  312  can have a thickness of about 0.04 inches and the concentric vertical fins  304 - 310  disposed between the inner most concentric vertical fin  302  and an outermost concentric vertical fin  312  can have a thickness of about 0.06 inches. 
     The plurality of concentric vertical fins  300  can be configured to couple to a side surface (e.g., cover ring) that rests on an outer periphery of the substrate support  106  using one or more suitable coupling device, e.g., screws, bolts, nuts, and the like. Alternative or additionally, the plurality of concentric vertical fins  300  can be configured to couple to (or rest upon) the bottom area  210  using one or more suitable coupling device, e.g., screws, bolts, nuts, and the like. 
     In accordance with at least some embodiments, an anode to cathode ratio can vary based on a configuration of the shield  200  of  FIGS. 2-4 . For example, with respect to  FIG. 2 , the shield  200  can have an effective anode area (e.g., planar area) of about 370 in 2  to about 470 in 2  and the target  114  can have an effective cathode area (e.g., planar area) of about 132 in 2  to about 135 in 2  (e.g., an anode to cathode ratio of about 2.74 to about 3.56). For example, in at least some embodiments, the shield  200  can have an effective anode area of about 370 in 2  to about 380 in 2  and the target  114  can have an affective anode area of about 132 in 2  to about 135 in 2 . 
     Moreover, with respect to  FIGS. 3 and 4 , the combination of the shield  200  and the concentric vertical fins  300  can provide an effective anode area of about 800 in 2  to about 1350 in 2  and the target  114  can again have an effective anode area of about 132 in 2  to about 135 in 2  (e.g., an anode to cathode ratio of about 5.90 to about 9.46). For example, in at least some embodiments, the shield  200  can provide an effective anode area of about 320 in 2  to about 420 in 2 , e.g., the shield  200  has a slightly less effective anode area because some of the bottom area  210  of the shield  200  is covered by the concentric vertical fins  300 , which can have an effective anode area of by about 480 in 2  to about 870 in 2 , thus increasing an overall effective anode area to the about 800 in 2  to about 1350 in 2 . 
     In at least some embodiments, a shield  500  can include an inner wall that comprises a plurality of spaced-apart concentric walls  502  extending upward from a bottom of the shield  500  to define a plurality of vertical wells  504 . In at least some embodiments, a height of each of the plurality of spaced-apart concentric walls  502  progressively decreases from an outermost wall  506  to an innermost wall  508 . For example, the outermost wall  506  can have a height of about 3.75 inches to about 4.25 inches, and in at least some embodiments, can have a height of about 4.0 inches. A wall  510  can have a height of about 3.25 inches to about 3.75 inches, and in at least some embodiments, can have a height of about 3.5 inches. A wall  512  can have a height of about 2.75 inches to about 3.25 inches, and in at least some embodiments, can have a height of about 3.0 inches. A wall  514  can have a height of about 2.25 inches to about 2.75 inches, and in at least some embodiments, can have a height of about 2.5 inches. The innermost wall  508  can have a height of about 1.75 inches to about 2.25 inches, and in at least some embodiments, can have a height of about 2.0 inches. 
     Similarly, the outermost wall  506  can have a diameter of about 14.55 inches to about 15.05 inches, and in at least some embodiments, can have a diameter of about 14.80 inches. The wall  510  can have a diameter of about 13.35 inches to about 13.85 inches, and in at least some embodiments, can have a diameter of about 13.60 inches. The wall  512  can have a diameter of about 12.35 inches to about 13.85 inches, and in at least some embodiments, can have a diameter of about 12.60 inches. The wall  514  can have a diameter of about 11.55 inches to about 12.05 inches, and in at least some embodiments, can have a diameter of about 11.80 inches. The innermost wall  508  can have a diameter of about 10.75 inches to about 11.25 inches, and in at least some embodiments, can have a diameter of about 11.00 inches. 
     Moreover, with respect to  FIG. 5 , the shield  500  and the spaced-apart concentric walls  502  can provide an effective anode area of about 1075 in 2  to about 1200 in 2  and the target  114  can have an effective anode area of about 132 in 2  to about 135 in 2  (e.g., an anode to cathode ratio of about 8.00 to about 9.10). For example, in at least some embodiments, the shield  500  can provide an effective anode area of about 1118 in 2  to about 1190 in 2 . 
     Returning to  FIG. 1 , the chamber lid  101  rests on the ledge  140  of the upper grounded enclosure wall  116 . Similar to the lower grounded enclosure wall  110 , the upper grounded enclosure wall  116  may provide a portion of the RF return path between the upper grounded enclosure wall  116  and the grounding assembly  103  of the chamber lid  101 . However, other RF return paths are possible, such as via the grounded shield  138 . 
     As discussed above, the shield  138  extends downwardly and may include one or more sidewalls configured to surround the first volume  120 . The shield  138  extends along, but is spaced apart from, the walls of the upper grounded enclosure wall  116  and the lower grounded enclosure wall  110  downwardly to below a top surface of the substrate support  106  and returns upwardly until reaching a top surface of the substrate support  106  (e.g., forming a u-shaped portion at the bottom of the shield  138 ). 
     A first ring  148  (e.g., a cover ring) rests on the top of the u-shaped portion (e.g., a first position of the first ring  148 ) when the substrate support  106  is in its lower, loading position (not shown) but rests on the outer periphery of the substrate support  106  (e.g., a second position of the first ring  148 ) when the substrate support  106  is in its upper, deposition position (as illustrated in  FIG. 1 ) to protect the substrate support  106  from sputter deposition. 
     An additional dielectric ring  111  may be used to shield the periphery of the substrate  108  from deposition. For example, the additional dielectric ring  111  may be disposed about a peripheral edge of the substrate support  106  and adjacent to the substrate processing surface  109 , as illustrated in  FIG. 1 . 
     The first ring  148  may include protrusions extending from a lower surface of the first ring  148  on either side of the inner upwardly extending u-shaped portion of the bottom of the shield  138 . An innermost protrusion may be configured to interface with the substrate support  106  to align the first ring  148  with respect to the shield  138  when the first ring  148  is moved into the second position as the substrate support is moved into the processing position. For example, a substrate support facing surface of the innermost protrusion may be tapered, notched or the like to rest in/on a corresponding surface on the substrate support  106  when the first ring  148  is in the second position. 
     In some embodiments, a magnet  152  may be disposed about the chamber body  104  for selectively providing a magnetic field between the substrate support  106  and the target  114 . For example, as shown in  FIG. 1 , the magnet  152  may be disposed about the outside of the enclosure wall  110  in a region just above the substrate support  106  when in processing position. In some embodiments, the magnet  152  may be disposed additionally or alternatively in other locations, such as adjacent the upper grounded enclosure wall  116 . The magnet  152  may be an electromagnet and may be coupled to a power source (not shown) for controlling the magnitude of the magnetic field generated by the electromagnet. 
     The chamber lid  101  generally includes the grounding assembly  103  disposed about the target assembly  102 . The grounding assembly  103  may include a grounding plate  156  having a first surface  157  that may be generally parallel to and opposite a backside of the target assembly  102 . A grounding shield  112  may extend from the first surface  157  of the grounding plate  156  and surround the target assembly  102 . The grounding assembly  103  may include a support member  175  to support the target assembly  102  within the grounding assembly  103 . 
     In some embodiments, the support member  175  may be coupled to a lower end of the grounding shield  112  proximate an outer peripheral edge of the support member  175  and extends radially inward to support a seal ring  181 , the target assembly  102  and optionally, a dark space shield (e.g., that may be disposed between the shield  138  and the target assembly  102 , not shown). The seal ring  181  may be a ring or other annular shape having a desired cross-section to facilitate interfacing with the target assembly  102  and with the support member  175 . The seal ring  181  may be made of a dielectric material, such as ceramic. The seal ring  181  may insulate the target assembly  102  from the ground assembly  103 . 
     The support member  175  may be a generally planar member having a central opening to accommodate the shield  138  and the target  114 . In some embodiments, the support member  175  may be circular, or disc-like in shape, although the shape may vary depending upon the corresponding shape of the chamber lid and/or the shape of the substrate to be processed in the process chamber  100 . In use, when the chamber lid  101  is opened or closed, the support member  175  maintains the shield  138  in proper alignment with respect to the target  114 , thereby minimizing the risk of misalignment due to chamber assembly or opening and closing the chamber lid  101 . 
     The target assembly  102  may include a source distribution plate  158  opposing a backside of the target  114  and electrically coupled to the target  114  along a peripheral edge of the target  114 . The target  114  may comprise a source material  113  to be deposited on a substrate, such as the substrate  108  during sputtering, such as a metal, metal oxide, metal alloy, magnetic material, or the like. In some embodiments, the target  114  may include a backing plate  162  to support the source material  113 . The backing plate  162  may comprise a conductive material, such as copper-zinc, copper-chrome, or the same material as the target, such that RF, and optionally DC, power can be coupled to the source material  113  via the backing plate  162 . Alternatively, the backing plate  162  may be non-conductive and may include conductive elements (not shown) such as electrical feedthroughs or the like. 
     A conductive member  164  may be disposed between the source distribution plate and the backside of the target  114  to propagate RF energy from the source distribution plate to the peripheral edge of the target  114 . The conductive member  164  may be cylindrical and tubular, with a first end  166  coupled to a target-facing surface of the source distribution plate  158  proximate the peripheral edge of the source distribution plate  158  and a second end  168  coupled to a source distribution plate-facing surface of the target  114  proximate the peripheral edge of the target  114 . In some embodiments, the second end  168  is coupled to a source distribution plate facing surface of the backing plate  162  proximate the peripheral edge of the backing plate  162 . 
     The target assembly  102  may include a cavity  170  disposed between the backside of the target  114  and the source distribution plate  158 . The cavity  170  may at least partially house a magnetron assembly  196 . The cavity  170  is at least partially defined by the inner surface of the conductive member  164 , a target facing surface of the source distribution plate  158 , and a source distribution plate facing surface (e.g., backside) of the target  114  (or backing plate  162 ). In some embodiments, the cavity  170  may be at least partially filled with a cooling fluid, such as water (H 2 O) or the like. In some embodiments, a divider (not shown) may be provided to contain the cooling fluid in a desired portion of the cavity  170  (such as a lower portion, as shown) and to prevent the cooling fluid from reaching components disposed on the other side of the divider. 
     An insulative gap  180  is provided between the grounding plate  156  and the outer surfaces of the source distribution plate  158 , the conductive member  164 , and the target  114  (and/or backing plate  162 ). The insulative gap  180  may be filled with air or some other suitable dielectric material, such as a ceramic, a plastic, or the like. The distance between the grounding plate  156  and the source distribution plate  158  depends on the dielectric material between the grounding plate  156  and the source distribution plate  158 . Where the dielectric material is predominantly air, the distance between the grounding plate  156  and the source distribution plate  158  should be between about 5 to about 40 mm. 
     The grounding assembly  103  and the target assembly  102  may be electrically separated by the seal ring  181  and by one or more of insulators  160  disposed between the first surface  157  of the grounding plate  156  and the backside of the target assembly  102 , e.g., a non-target facing side of the source distribution plate  158 . 
     The target assembly  102  has the RF power source  182  connected to an electrode  154  (e.g., a RF feed structure). The RF power source  182  may include an RF generator and a matching circuit, for example, to minimize reflected RF energy reflected back to the RF generator during operation. For example, RF energy supplied by the RF power source  182  may range in frequency from about 13.56 MHz and to about 162 MHz or above. For example, non-limiting frequencies such as 13.56 MHz, 27.12 MHz, 60 MHz, or 162 MHz can be used. 
     In some embodiments, a second energy source  183  may be coupled to the target assembly  102  to provide additional energy to the target  114  during processing. In some embodiments, the second energy source  183  may be a DC power source to provide DC energy, for example, to enhance a sputtering rate of the target material (and hence, a deposition rate on the substrate). In some embodiments, the second energy source  183  may be a second RF power source, similar to the RF power source  182 , to provide RF energy, for example, at a second frequency different than a first frequency of RF energy provided by the RF power source  182 . In embodiments where the second energy source  183  is a DC power source, the second energy source may be coupled to the target assembly  102  in any location suitable to electrically couple the DC energy to the target  114 , such as the electrode  154  or some other conductive member (such as the source distribution plate  158 ). In embodiments where the second energy source  183  is a second RF power source, the second energy source may be coupled to the target assembly  102  via the electrode  154 . 
     The electrode  154  may be cylindrical or otherwise rod-like and may be aligned with a central axis  186  of the process chamber  100  (e.g., the electrode  154  may be coupled to the target assembly at a point coincident with a central axis of the target, which is coincident with the central axis  186 ). The electrode  154 , aligned with the central axis  186  of the process chamber  100 , facilitates applying RF energy from the RF power source  182  to the target  114  in an asymmetrical manner (e.g., the electrode  154  may couple RF energy to the target at a “single point” aligned with the central axis of the PVD chamber). The central position of the electrode  154  helps to eliminate or reduce deposition asymmetry in substrate deposition processes. The electrode  154  may have any suitable diameter, however, the smaller the diameter of the electrode  154 , the closer the RF energy application approaches a true single point. For example, although other diameters may be used, in some embodiments, the diameter of the electrode  154  may be about 0.5 to about 2 inches. The electrode  154  may generally have any suitable length depending upon the configuration of the PVD chamber. In some embodiments, the electrode may have a length of between about 0.5 to about 12 inches. The electrode  154  may be fabricated from any suitable conductive material, such as aluminum, copper, silver, or the like. 
     The electrode  154  may pass through an opening in the grounding plate  156  and is coupled to a source distribution plate  158 . The grounding plate  156  may comprise any suitable conductive material, such as aluminum, copper, or the like. Open spaces between the one or more insulators  160  allow for RF wave propagation along the surface of the source distribution plate  158 . In some embodiments, the one or more insulators  160  may be symmetrically positioned with respect to the central axis  186  of the process chamber  100  Such positioning may facilitate symmetric RF wave propagation along the surface of the source distribution plate  158  and, ultimately, to a target  114  coupled to the source distribution plate  158 . The RF energy may be provided in a more symmetric and uniform manner as compared to conventional PVD chambers due, at least in part, to the central position of the electrode  154 . 
     One or more portions of a magnetron assembly  196  may be disposed at least partially within the cavity  170 . The magnetron assembly provides a rotating magnetic field proximate the target to assist in plasma processing within the process chamber 104 . In some embodiments, the magnetron assembly  196  may include a motor  176 , a motor shaft  174 , a gear box  178 , a gear box shaft  184 , and a rotatable magnet (e.g., a plurality of magnets  188  coupled to a magnet support member  172 ). 
     The magnetron assembly  196  is rotated within the cavity  170 . For example, in some embodiments, the motor  176 , motor shaft  174 , gear box  178 , and gear box shaft  184  may be provided to rotate the magnet support member  172 . In some embodiments (not shown), the magnetron drive shaft may be disposed along the central axis of the chamber, with the RF energy coupled to the target assembly at a different location or in a different manner. As illustrated in  FIG. 1 , in some embodiments, the motor shaft  174  of the magnetron may be disposed through an off-center opening in the grounding plate  156 . The end of the motor shaft  174  protruding from the grounding plate  156  is coupled to a motor  176 . The motor shaft  174  is further disposed through a corresponding off-center opening through the source distribution plate  158  (e.g., a first opening  146 ) and coupled to a gear box  178 . In some embodiments, one or more second openings  198  may be disposed though the source distribution plate  158  in a symmetrical relationship to the first opening  146  to advantageously maintain axisymmetric RF distribution along the source distribution plate  158 . The one or more second openings  198  may also be used to allow access to the cavity  170  for items such as sensors or the like. 
     The gear box  178  may be supported by any suitable means, such as by being coupled to a bottom surface of the source distribution plate  158 . The gear box  178  may be insulated from the source distribution plate  158  by fabricating at least the upper surface of the gear box  178  from a dielectric material, or by interposing an insulator layer  190  between the gear box  178  and the source distribution plate  158 , or the like. The gear box  178  is further coupled to the magnet support member  172  via the gear box shaft  184  to transfer the rotational motion provided by the motor  176  to the magnet support member  172  (and hence, the plurality of magnets  188 ). The gear box shaft  184  may advantageously be coincident with the central axis  186  of the process chamber  100 . 
     The magnet support member  172  may be constructed from any material suitable to provide adequate mechanical strength to rigidly support the plurality of magnets  188 . The plurality of magnets  188  may be configured in any manner to provide a magnetic field having a desired shape and strength to provide a more uniform full-face erosion of the target as described herein. 
     Alternatively, the magnet support member  172  may be rotated by any other means with sufficient torque to overcome the drag caused on the magnet support member  172  and attached plurality of magnets  188 , for example due to the cooling fluid, when present, in the cavity  170 . 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.