Abstract:
A sputtering target assembly and method for bonding a sputtering target to a backing plate is disclosed. When insulatively bonding a sputtering target to a backing plate, it is necessary to ensure that the bonding material has good thermal conductivity so that the temperature of the target can be effectively controlled. It is also important to not have electrical conductivity through the bonding materials. In order to achieve both goals, it is beneficial to utilize an elastomer with diamond powder filler. Diamond power has very good thermal conductivity, and it also has very good dielectric strength. Diamond is a thermally effective and cost effective substitute for silver in insulative bonding.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is related to co-pending U.S. patent application Ser. No. 11/225,922, filed Sep. 13, 2005, U.S. patent application Ser. No. 11/225,923, filed Sep. 13, 2005, and U.S. Provisional Application Ser. No. 60/633,939 filed Nov. 4, 2005. Each of the aforementioned related patent applications is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     Embodiments of the present invention generally relate to a sputtering target assembly and a method of bonding a sputtering target to a backing plate.  
         [0004]     2. Description of the Related Art  
         [0005]     In sputtering large area substrates (i.e. flat panel displays, solar cells, etc.), some problems are encountered including non-uniform deposition and low target utilization. Therefore, there is a need for an improved sputtering apparatus and method.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention generally provides a sputtering target bonded to a backing plate. To bond the sputtering target to the backing plate, the inventors propose using a bonding material that comprises diamond or ceramic or a combination thereof.  
         [0007]     In a first embodiment, a sputtering target assembly is disclosed. The sputtering target assembly has a sputtering target, a backing plate, and material bonding the target to the backing plate. The bonding material has diamond in it.  
         [0008]     In a second embodiment, a method of bonding a target to a backing plate is disclosed. The method involves providing a sputtering target, providing a backing plate, providing a bonding material between the target and the backing plate, and pressing the target, the backing plate, and the bonding material together and thermally curing. The bonding material has diamond in it.  
         [0009]     In a third embodiment, a sputtering target assembly is disclosed. The target assembly has a sputtering target, a backing plate, and material bonding the target to the backing plate. The material bonding the target to the backing plate has a ceramic material with a thermal conductivity of greater than 0.1 W/cmK. The material bonding the target to the backing plate does not have silver in it. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     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.  
         [0011]      FIG. 1  is a vertical cross-sectional view of a processing region formed in an exemplary physical vapor deposition chamber.  
         [0012]      FIG. 2  is a vertical cross-sectional view of an exemplary physical vapor deposition chamber.  
         [0013]      FIG. 3  is a vertical cross-sectional view of a processing region formed in an exemplary physical vapor deposition chamber.  
         [0014]      FIG. 4  is a sputtering target assembly using diamond particles.  
         [0015]      FIG. 5A  illustrates a plan view of one embodiment of the multizone target assembly illustrated in  FIG. 2  that contains two target sections.  
         [0016]      FIG. 5B  illustrates a plan view of one embodiment of the multizone target assembly illustrated in  FIG. 2  that contains two target sections that are formed from multiple tiles.  
         [0017]      FIG. 5C  illustrates a plan view of one embodiment of the multizone target assembly that contains five concentric target sections.  
         [0018]      FIG. 5D  illustrates a plan view of one embodiment of the multizone target assembly that contains seven target sections.  
         [0019]      FIG. 6  is a vertical cross-sectional view of a processing region formed in an exemplary physical vapor deposition chamber.  
         [0020]      FIG. 7A  is a vertical cross-sectional view of a processing region formed in an exemplary physical vapor deposition chamber.  
         [0021]      FIG. 7B  illustrates a plan view of one embodiment of the multizone target assembly and process gas delivery assembly, which may be useful to perform aspects of the invention disclosed herein.  
         [0022]      FIG. 7C  illustrates a plan view of one embodiment of the multizone target assembly and process gas delivery assembly, which may be useful to perform aspects of the invention disclosed herein.  
         [0023]      FIG. 7D  illustrates a plan view of one embodiment of the multizone target assembly and process gas delivery assembly, which may be useful to perform aspects of the invention disclosed herein. 
     
    
     DETAILED DESCRIPTION  
       [0024]     The present invention involves insulatively boding sputtering targets to backing plates while maintaining a good thermal conductivity. Having a good thermal conductivity is necessary in insulatively bonding a target to a backing plate so that the temperature of the sputtering target can be controlled.  
         [0000]     Target Assembly Hardware  
         [0025]      FIG. 2  illustrates a vertical cross-sectional view of one embodiment of a processing chamber  10  that may be used to perform aspects of the invention described herein. In general, 4 the various embodiments described herein utilize a multizone target assembly  124  that is used to generate a plasma of varying density in the processing region  15  of the processing chamber  10  by separately biasing different target sections  127 A,  127 B to achieve a desired sputter deposition profile across the substrate surface. Referring to  FIG. 2 , the processing region  15  is generally the region formed between the multizone target assembly  124 , a surface of a substrate  12  positioned on the substrate support  61 , and the shield  50 . The term sputter deposition profile is intended to describe the deposited film thickness as measured across the substrate processing surface (element  12 A). In one aspect, the sputter deposition profile is adjusted by tailoring the plasma density profile throughout the processing region  15 , by varying the voltage applied to the target sections.  FIG. 2  illustrates one embodiment of the multizone target  124  that contains two target sections (e.g., elements  127 A and  127 B).  FIG. 2  also illustrates a substrate  12  that is positioned in a processing position in the processing region  15 .  
         [0026]     In one aspect, the target sections  127 A,  127 B are generally made from the same or similar materials, which are to be sputter deposited on the processing surface  12 A of the substrate  12 . Typical elements or materials that the target sections may contain include, but are not limited to molybdenum, aluminum, aluminum neodymium alloys, copper, titanium, tantalum, tungsten, chromium, indium tin oxide, zinc, or zinc oxide. Thus, in one aspect, the target sections are made from metals that are doped, or alloyed, with a number of different components, such as a zinc material that is doped the elements aluminum (Al), silicon (Si), and/or gallium (Ga), or a copper material that is doped the elements indium (In), gallium (Ga), and/or selenium (Se).  
         [0027]     In general, the processing chamber  10  contains a lid assembly  20  and a lower chamber assembly  35 . The lower chamber assembly  35  generally contains a substrate support assembly  60 , chamber body assembly  40 , a shield  50 , a process gas delivery system  45  and a shadow frame  52 . The shadow frame  52  is used to shadow the edge of the substrate to prevent or minimize the amount of deposition on the edge of a substrate  12  and substrate support  61  during processing (see  FIG. 2 ). The chamber body assembly  40  contains one or more chamber walls  41  and a chamber base  42 . The one or more chamber walls  41 , the chamber base  42  and a surface of the multizone target assembly  124  form a vacuum processing area  17  that has a lower vacuum region  16  and a processing region  15 . In one aspect, a shield mounting surface  50 A of the shield  50  is mounted on or connected to a grounded chamber shield support  43  formed in the chamber walls  41  to ground the shield  50 . In one aspect, the process chamber  10  contains a process gas delivery system  45  that has one or more gas sources  45 A that are in fluid communication with one or more inlet ports  45 B that are used to deliver a process gas to the vacuum processing area  17 . In one aspect, discussed below in conjunction with  FIG. 7A , the process gas could be delivered to the processing region  15  through the multizone target assembly  124 . Process gases that may be used in PVD type applications are, for example, inert gases such as argon or other reactive type gases such as nitrogen or oxygen containing gas sources. In one embodiment, the substrate support  61  may contain RF biasable elements  61 A embedded within the substrate support  61  that can be used to capacitively RF couple the substrate support  61  to the plasma generated in the processing region  15  by use of an RF power source  67  and RF matching device  66 . The ability to RF bias the substrate support  61  may be useful to help improve the plasma density, improve the deposition profile on the substrate, and increase the energy of the deposited material at the surface of the substrate.  
         [0028]     The substrate support assembly  60  generally contains a substrate support  61 , a shaft  62  that is adapted to support the substrate support  61 , and a bellows  63  that is sealably connected to the shaft  62  and the chamber base  42  to form a moveable vacuum seal that allows the substrate support  61  to be positioned in the lower chamber assembly  35  by the lift mechanism  65 . The lift mechanism  65  may contain a conventional linear slide (not shown), pneumatic air cylinder (not shown) and/or DC servo motor that is attached to a lead screw (not shown), which are adapted to position the substrate support  61 , and substrate  12 , in a desired position in the processing region  15 .  
         [0029]     Referring to  FIG. 2 , the lower chamber assembly  35  will also generally contain a substrate lift assembly  70 , slit valve  46 , and vacuum pumping system  44 . The lift assembly  70  contains three or more lift pins  74 , a lift plate  73 , a lift actuator  71 , and a bellows  72  that is sealably connected to the lift actuator  71  and the chamber base  42  so that the lift pins  74  can remove and replace a substrate positioned on a robot blade (not shown) that has been extended into the lower chamber assembly  35  from a central transfer chamber (not shown). The extended robot blade enters the lower chamber assembly  35  through the access port  32  in the chamber wall  41  and is positioned above the substrate support  61  that is positioned in a transfer position (not shown). The vacuum pumping system  44  (elements  44 A and  44 B) may generally contain a cryo-pump, turbo pump, cryo-turbo pump, rough pump, and/or roots blower to evacuate the lower vacuum region  16  and processing region  15  to a desired base and/or processing pressure. A slit valve actuator (not shown) which is adapted to position the slit valve  46  against or away from the one or more chamber walls  41  may be a conventional pneumatic actuator which are well known in the art.  
         [0030]     To control the various processing chamber  10  components, power supplies  128 A &amp; B, gas supplies, and process variables during a deposition process, a controller  101  is used. The controller  101  is typically a microprocessor-based controller. The controller  101  is configured to receive inputs from a user and/or various sensors in the plasma processing chamber and appropriately control the plasma processing chamber components in accordance with the various inputs and software instructions retained in the controller&#39;s memory. The controller  101  generally contains memory and a CPU which are utilized by the controller to retain various programs, process the programs, and execute the programs when necessary. The memory is connected to the CPU, and may be one or more of a readily available memory, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. Software instructions and data can be coded and stored within the memory for instructing the CPU. The support circuits are also connected to the CPU for supporting the processor in a conventional manner. The support circuits may include cache, power supplies, clock circuits; input/output circuitry, subsystems, and the like all well known in the art. A program (or computer instructions) readable by the controller  101  determines which tasks are performable in the plasma processing chamber. Preferably, the program is software readable by the controller  101  and includes instructions to monitor and control the plasma process based on defined rules and input data.  
         [0031]     The lid assembly  20  contains a multizone target assembly  124 , a lid enclosure  22 , a ceramic insulator  26 , one or more o-ring seals  29  and one or more magnetron assemblies  23  that are positioned in a target backside region  21 . In one aspect, the ceramic insulator  26  is not required to provide electrical isolation between the backing plate  125  of the multizone target assembly  124  and the chamber body assembly  40 . Generally, each magnetron assembly  23  will have at least one magnet  27  that has a pair of opposing magnetic poles (i.e., north (N) and south (S)) that create a magnetic field (B-field) that passes through the multizone target assembly  124  and the processing region  15  (see element “B” in  FIG. 4 ).  FIG. 2  illustrates a vertical cross-section of one embodiment of a processing chamber  10  that has one magnetron assembly  23  that contains three magnets  27 , which are positioned in the target backside region  21  at the back of the multizone target assembly  124 . An exemplary magnetron assembly, that may be adapted to benefit the invention described herein, is further described in the commonly assigned U.S. patent application Ser. No. 10/863,152, filed Jun. 7, 2004, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/534,952, filed Jan. 7, 2004, and is hereby incorporated by reference in its entirety to the extent not inconsistent with the claimed invention.  
         [0032]     To perform a PVD deposition process, the controller  101  commands the vacuum pumping system  44  to evacuate the processing chamber  10  to a predetermined pressure/vacuum so that the plasma processing chamber  10  can receive a substrate  12  from a system robot (not shown) mounted to a central transfer chamber (not shown) which is also under vacuum. To transfer a substrate  12  to the processing chamber  10 , the slit valve  46 , which seals off the processing chamber  10  from the central transfer chamber, opens to allow the system robot to extend through the access port  32  in the chamber wall  41 . The lift pins  74  then remove the substrate  12  from the extended system robot, by lifting the substrate from the extended robot blade (not shown). The system robot then retracts from the processing chamber  10  and the slit valve  46  closes to isolate the processing chamber  10  from the central transfer chamber. The substrate support  61  then lifts the substrate  12  from the lift pins  74  and moves the substrate  12  to a desired processing position below the multizone target assembly  124 .  
         [0033]     After achieving a desired base pressure, a desired flow of a processing gas is injected into the processing region  15  and a bias voltage is applied to at least one of the target sections  127 A,  127 B of the multizone target assembly  124  by use of a power supply  128 A-B attached to the target section that is to be biased. The application of a bias voltage by the power supply causes ionization and dissociation of the gas in the processing region  15  and the generated ions subsequently bombard the surface of the cathodically biased target section(s) and thus “sputter” the target atoms from the target surface.  
         [0034]     A percentage of the “sputtered” target atoms land on the surface of the substrate positioned on the surface of the substrate support  61 . The ion energy and ion flux near the target sections, which is related to the magnitude of the bias voltage applied to each of the biased target sections, can thus be tailored to assure a uniform or desired distribution is achieved throughout the processing region. Each target section that is not biased can either be electrically floating or be grounded. In either case, generally no sputtering activity will occur on these target sections during this process step. The term “grounded” as used herein is generally intended to describe a direct or in direct electrical connection between a component that is to be “grounded” and the anode surfaces (e.g., element  50 ) positioned inside the processing chamber  10 .  
         [0000]     Magnetron Design For Processing  
         [0035]      FIG. 3  illustrates a close up view of the processing region  15  and lid assembly  20  of one embodiment of the process chamber  10 . The embodiment illustrated in  FIG. 3  has a lid assembly  20  that has a multizone target assembly  124  and at least one magnetron assembly  23  positioned adjacent to each of the target sections of the multizone target assembly  124 . Typically, to improve utilization of the target material and improve deposition uniformity it is common to translate (e.g., raster; scan, and/or rotate) each of the magnetron assemblies in at least one of the directions that are parallel to the target surface  127 C-D by use of one or more magnetron actuators  24 A and  24 B. The magnetron actuator(s) may be a linear motor, stepper motor, or DC servo motor that are adapted to position and move the magnetron assembly in a desired direction at a desired speed by use of commands from the controller  101 . A translation mechanism used to move the magnetron, along with magnet orientations in the magnetron assembly, that may be adapted to benefit the invention described herein is further described in the commonly assigned U.S. patent application Ser. No. 10/863,152, filed Jun. 7, 2004, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/534,952, filed Jan. 7, 2004, and is hereby incorporated by reference in its entirety to the extent not inconsistent with the claimed invention.  
         [0036]     During the PVD deposition process a large portion of the generated plasma in the processing region  15  is formed and is retained below the magnetron assemblies  23  due to the magnetic fields (elements “B”) containment of the electrons found in the processing region  15 . The optimum magnetic field profile for a processing chamber  10  will vary from one substrate size to another, from the ratio of the anode (e.g., grounded surface) to cathode (e.g., target) surface area, target to substrate spacing, PVD process pressure, motion of the magnetron across the target face, desired deposition rate, and type of material that is being deposited. The effectiveness of the magnetron  23  on reducing the center to edge deposited thickness variation is affected by the magnetic permeability; of the target material(s). Therefore, in some case the magnetron magnetic field pattern may need to be adjusted based on the type of multizone target assembly  124  material(s) and their thickness(es).  
         [0037]     The magnetron assembly  23  has an effect on the shape and uniformity of the PVD deposited layer due to the strength and orientation of the magnetic fields generated by the magnetron assembly  23 . In general, each of the magnetron assemblies  23  (elements  23 A-B) will contain at least one magnet  27 . The magnets  27  may be permanent magnets (e.g., neodymium, samarium-cobalt, ceramic, or Alnico) or electromagnets.  
         [0038]     Referring to  FIG. 3 , in one embodiment of the processing chamber  10 , the one or more magnetron assemblies  23  are distributed across the multizone target assembly  124  to balance out the difference in current flow between the center and edge of the target caused by the differing resistance to the anode (e.g., ground) for each of these paths. The control of the magnetic field distribution from the center to the edge of the multizone target assembly  124  is used to control and improve plasma density and thus the deposition uniformity across the processing surface, which is positioned near the surface of the target sections (elements  127 C-D). In one aspect, the magnetic field strength of the magnetron assemblies  23  is configured to deliver a higher magnetic field strength in the target sections (e.g., element  127 A  FIG. 4A ) near the center rather than at the edge of the multizone target.  
         [0039]     In one aspect, each of the magnetron assemblies  23 A or  23 B are adapted to translate across the target section(s) in unison by use of magnetron actuator(s) (elements  24 A-B in  FIG. 3 ) to control plasma density uniformity and improve the deposition profile across the substrate surface. In another aspect, each of the magnetron assemblies  23 A or  23 B are adapted to be separately translated across the target sections by use of one or more magnetron actuators (element  24 A-B  FIG. 4A ). In one aspect, it may be desirable to limit the translation of the magnetron assemblies to positions that minimize the interaction with the other target sections and magnetron assemblies  23  to improve the deposition uniformity profile across the substrate.  
         [0000]     Insulative Bonding  
         [0040]      FIG. 4  shows an exemplary embodiment of the present invention.  FIG. 4  shows a backing plate  1 , bonded to a sputtering target  2  using a bonding material  5  that comprises diamond or a ceramic or combinations thereof and a dielectric screen. The screen is used as a spacer between the target and the backing plate. The screen could be a dielectric screen or glass beads. Exemplary dielectric screens include nylon screens and glass fiber screens. Dielectric dots such as polyimide dots or thin glass dots with flat or hemisphere shape could also be used. The screen preferably has a circular shaped cross section. So long as the screen can provide reliable spacing between the target and the backing plate without negatively affecting the adhesion, the screen size can be fairly large. Ideally, the bonding material is no more than 1 mm thick. The target is bonded to the backing plate by pressing the target, the backing plate, and the bonding material together to thermally cure at temperature between 30° C. and 200° C.  
         [0041]     Fine diamond powders are used as filler in the elastomer that forms a dielectric bond. Diamond, while expensive in jewelry, is relatively cheap in small particle sizes. Preferably, the size of the diamond power should be sized so that the highest thermal conductivity can be achieved while using the lowest content of diamond possible. By using as little diamond as possible, costs can remain low. Also, the more diamond that is used, the less elastomer that is used. An exemplary weight or volume ratio of elastomer to diamond particles is 1:1. Sufficient elastomer is necessary to form a strong bond between the target and the backing plate. Diamond sizes of below 1 micron are preferred. Particularly preferable diamond sizes include about 10 nm to about 500 nm. The diamond particles should be uniform with a mono-disperse size distribution with a standard distribution of less than 50%. Preferably, the standard distribution is less than 10%.  
         [0042]     Diamond has a very good thermal conductivity. The thermal conductivity of diamond is about 6 times greater than that of silver. Even better, the electrical resistivity of diamond is about 19 orders of magnitude higher than silver. Diamond also compares favorably to glass with regards to the dielectric strength. Diamond also has a relatively low loss tangent so that it can be used for bonding targets powered by high frequency RF power. The table below shows a comparison of physical properties of silver, glass, and diamond at room temperature.  
                                             TABLE                       Property   Silver   Glass (SiO2)   Diamond                                Thermal conductivity (W/cmK)   4.29   0.01   20       Electrical resistivity (ohm-cm)   1.6 × 10 −6         4 × 10 9 -3 × 10 10     1 × 10 13 -1 × 10 16         Thermal expansion coefficient (1/K)    18 × 10 −6     5 × 10 −6 -9 × 10 −6     1.1 × 10 −6         Dielectric constant       3.8   5.7       Dielectric strength (V/cm)       &gt;10,000,000   10,000,000       Loss tangent at 106 Hz       &lt;0.0003   &lt;0.0002                  
 
         [0043]     Instead of diamond, other particle fillers can also be used. Some of the materials include ceramics or other composed materials. Exemplary materials include aluminum nitride, aluminum oxide, beryllium oxide, boron nitride, silicon carbide, cerium oxide, tin oxide, magnesium oxide, stannic oxide, zinc oxide, cupric oxide, or yttria. Ideally, the thermal conductivity should be greater than 0.1 W/cmK. For the instant invention, silver should not be used.  
         [0000]     Target Sections  
         [0044]      FIG. 5A  illustrates a plan view of one embodiment of the multizone target assembly  124  illustrated in  FIG. 2  that contains two target sections  127 A and  127 B. In this configuration, each of the target sections  127 A-B are formed from a single continuous piece of target material that will be sputter deposited onto the substrate surface. In one aspect, each of the target sections are formed from the same type of material so that the deposited film will have a uniform thickness and composition across the substrate surface. In one embodiment, as shown in  FIG. 5A , a first target region  127 A is “surrounded” by a second target region  127 B. The term “surrounded” as used herein is intended to describe a positional orientation in at least one plane where a first target region is positioned within or encircled by a second target region. In another embodiment of the multizone target assembly  124 , the target regions are “surrounded” and at least one axis of symmetry of a first target region  127 A is coincident to an axis of symmetry of a second target region  127 B. For example, the center point (element “C”) of each of the target sections (elements  127 A and  127 B) are coincident with each other. One will note that the shape and size of the target surfaces  127 C-D ( FIG. 3 ) of the target sections  127 A-B, as illustrated in FIGS.  5 A-D, is dependent on the size and dimensions of the substrate. In general, the total surface area of the target surfaces (e.g.,  127 C-D) will be larger than the surface area of the substrate to avoid deposition non-uniformities created by plasma non-uniformities at the edge of the multizone target assembly  124 . In one aspect, when the multizone target assembly  124  is used to deposit a layer on a rectangular flat panel display substrate, or rectangular solar cell type substrate, the target sections form an active target surface that extends at least a few centimeters past the edge of the substrate in each direction.  
         [0045]      FIG. 5B  illustrates a plan view of one embodiment of the multizone target assembly  124  illustrated in  FIG. 2  that contains two target sections  127 A and  127 B. In the configuration shown in  FIG. 5B , the outer target section  127 B is formed from multiple “plates” (elements A 1 -A 6 ), or “tiles,” that are generally made of the same target material. As flat panel display substrates are becoming larger (e.g., &gt;19,500 cm 2 ) it becomes cost prohibitive and in some cases technically impossible to form a target from a single monolithic plate. Therefore, targets formed from multiple plates that are electrically connected to each other, by welding, conductive bonding to a conductive backing plate or electrical connections formed by use of discrete wires, may be used to form each target section. In one aspect, the multiple plates are welded together by use of an e-beam welding process, a laser welding process, arc welding process or other comparable process that can be used to join materials together. Examples of exemplary techniques and physical shapes that may be used to form various target sections are further described in the U.S. patent application Ser. No. 10/888,383, filed Jul. 9, 2004 and U.S. patent application Ser. No. 11/158,270, filed Jun. 21, 2005, which are incorporated by reference herein in their entirety to the extent not inconsistent with the claimed aspects and description herein. Although,  FIG. 5B  illustrates one embodiment in which the outer target section  127 B is formed from multiple plates and the inner target is formed from a single plate, other embodiments of the invention may have more than one target section (e.g., element  127 A), or even all target sections, formed from a plurality of electrically connected plates.  
         [0046]      FIG. 5C  illustrates a plan view of one embodiment of the multizone target assembly  124  that contains five concentric target sections  127 E-I. In this configuration each target section can be separately biased at different potentials by use of a power supplies (not shown) attached to each target section. In one embodiment, one or more of the target sections may be grounded while other target sections are biased. For example, target sections  127 E,  127 G and  127 I may each be biased at some desired voltage, while target sections  127 F and  127 H may be grounded.  
         [0047]      FIGS. 5D  illustrates a plan view of one embodiment of the multizone target assembly  124  that contains seven target sections  127 L-S. In this configuration each target section can be separately biased at a different potential by use of a power supply (not shown) attached to each target section to improve the sputter deposition uniformity:  
         [0048]     It should be noted that while  FIGS. 2 and 3  generally illustrate a multizone target assembly  124  that has target sections that are in the same plane (e.g., horizontal plane) this configuration is not intended to be limiting as to the scope of the invention described herein. In one embodiment, the target section(s) near the center of the multizone target assembly are positioned a further distance from the surface of the substrate than the target section(s) near the edge of the multizone target assembly. In another embodiment, the target section(s) near the center of the multizone target-assembly are positioned closer to the surface of the substrate than the target section(s) near the edge of the multizone target assembly. Also, it should be noted that while  FIGS. 2 and 3  generally illustrate a multizone target assembly  124  that has target sections that have a surface (e.g.,  127 C and  127 D) that is generally parallel to the substrate surface in contact with the processing region  15 , other embodiments may orient at least part of one or more of the target sections such that they are not parallel to the substrate surface. Examples of shapes of the multizone target assembly surfaces (e.g.,  127 C and  127 D) may include, for example, a convex or concave shape.  
         [0000]     Multizone Target Assembly Hardware  
         [0049]      FIG. 6  illustrates an enlarged vertical cross-sectional view of one embodiment of the lid assembly  20  shown in  FIG. 2 . One will note that some of the elements shown in  FIG. 6  are not shown in  FIG. 2  for clarity reasons. The lid assembly  20 , as shown in  FIG. 6 , generally contains a multizone target assembly  124 , a lid enclosure  22 , a ceramic insulator  26 , one or more o-ring seals  29  and one or more magnetron assemblies  23  ( FIG. 2 ). The multizone target assembly  124  contains a backing plate  125 , an insulator  126 , and two or more target sections (e.g., elements  127 A and  127 B) that have a corresponding electrical connection (elements  129 A and  129 B) that connects each target section to its power supply (elements  128 A-B) so that it can be biased during processing. In one aspect, the multizone target assembly  124  is electrically isolated from the electrically grounded chamber walls  41  of the chamber body assembly  40  by use of an insulator  26 . This configuration may be useful to prevent or minimize arcing between the biased target sections and the backing plate  125  during processing. In another aspect, the insulator  126  is removed to allow the backing plate  125  to be in electrical communication with the chamber body assembly 40 components.  
         [0050]     In one aspect, the target sections are electrically isolated from each other and supported by the insulator  126 . In one aspect, the insulator  126  is made of an electrically insulative material, such as a ceramic material (e.g., aluminum oxides (Al 2 O 3 ), aluminum nitride (AlN), quartz (SiO 2 ), Zirconia (ZrO)), a polymeric material (e.g., polyimide (Vespel®)) or other suitable material that may be able to structurally withstand the temperatures seen by the multizone target assembly  124  during processing. The thickness of the insulator  126  is sized to provide electrical isolation between the target sections and between the target sections and the backing plate  125 . In one aspect, the target sections are brazed or bonded by conventional means to the insulator  126  at a bonded region  126 B. In another aspect, the target sections are mechanically fastened (e.g., bolts) to the insulator  126  by conventional means.  
         [0051]     In one aspect, the target sections are actively cooled by use of heat exchanging channels  125 A formed in the backing plate  125  to prevent the target sections or braze or bonding materials used to form the bonded region  126 B from being damaged by the temperatures achieved by the multizone target assembly  124  during processing. In this configuration the backing plate  125  is in thermal contact with the target sections through the insulator  126 , which is attached to the backing plate  125 . In one aspect, the insulator  126  is brazed, bonded or mechanically fastened to the backing plate  125  by conventional means to improve the thermal heat transfer between the insulator  126  and the backing plate  125 . The heat exchanging channels  125 A are in fluid communication with a primary heat exchanging device (not shown) that is adapted to deliver a heat exchanging fluid (e.g., DI water, perfluoropolyethers (e.g., Galden®)) at a desired temperature and flow rate through them. The backing plate  125  may be made from an aluminum alloy, stainless steel alloy, or other thermally conductive material, and is designed to structurally support the other components in the multizone target assembly  124 .  
         [0052]     In another aspect, the target sections and bonded region(s)  126 B are cooled by use of a plurality of cooling channels  126 A formed in the insulator  126 , or target sections. In one aspect, a heat exchanging fluid is delivered through the cooling channels  126 A to transfer the heat generated during processing away from the target sections. In one aspect, the heat exchanging fluid is delivered from a conventional heat exchanging fluid source (not shown) that is adapted to deliver the heat exchanging fluid at a desired temperature. In one aspect, the conventional heat exchanging fluid source is adapted to control the temperature of the heat exchanging fluid delivered to the cooling channels  126 A by use of a conventional refrigeration unit, resistive heater, and/or theromoelectric device. The heat exchanging fluid may be, for example, a gas (e.g., helium, nitrogen, or argon) or a liquid (e.g., DI water). In one aspect, the heat exchanging fluid is a gas, such as helium (He), that is delivered to the cooling channels  126 A and maintained at a pressure between 500 milliTorr to about 50 Torr to transfer heat from the target sections to the insulator  126  and backing plate  125 . In another aspect, a flow of helium is delivered to the cooling channels  126 A to transfer heat from the target sections to the insulator  126  and backing plate  125 . The cooling channels  126 A may be useful to prevent the material in the bonded regions  126 B, for example, indium braze materials or polymeric materials from overheating, which can cause the adhesive properties of the bonded region  126 B to fail. The cooling channels  126 A may be about 0.001 inches to about 1 inch in height (e.g., distance from the target section), while the width of the cooling channels  126 A may be optimized to assure adequate bonding area of the bonded regions  126 B formed between the insulator  126  and the target sections versus adequate cooling capacity.  
         [0053]     Referring to  FIGS. 2 and 6 , in one embodiment of the process chamber  10 , a vacuum pump  28  is used to evacuate the target backside region  21  to reduce the stress induced in the multizone target assembly  124  due to the pressure differential created between the processing region  15  and the target backside region  21 . The reduction in the pressure differential across the multizone target assembly  124  can be important for process chambers  10  that are adapted to process large area substrates greater than 2000 cm 2  to prevent the large deflections of the center of the multizone target assembly  124 . Large deflections are often experienced even when the pressure differential is about equal to atmospheric pressure (e.g., 14 psi).  
         [0054]     Referring to  FIGS. 2 and 7 A, in one aspect of the multizone target assembly  124 , a gap “G” is formed between the target sections to electrically isolate the target sections. The gap “G” may be between about 0.05 and about 100 millimeters (mm). In one aspect, the gap “G” is sized to be smaller than the dark space thickness so that a plasma will not be formed in the gap “G.” Selecting a desirable gap “G” dimension will help to prevent plasma attack of the bonded regions  126 B ( FIG. 6 ). Selection of a gap “G” smaller than the dark space thickness will also help to remove a source of particles due to redeposition of the sputtered material on the target surface and also prevent the plasma generated deposition from creating arcing path between target sections. One will note that the dark space thickness is dependent on the gas pressure in the processing region  15 , where generally the higher the pressure the smaller the dark space thickness.  
         [0055]      FIG. 7A  is vertical cross-sectional view of one embodiment of the multizone target assembly  124  that has a process gas delivery assembly  136  that contains at least one gas source  132 , at least one gas channel  133  and at least one exit port  134  that are adapted to deliver a processing gas (element “A”) to the. processing region  15 . In one embodiment of the process gas delivery assembly  136 , at least two or more of the exit ports  134  are connected to separate gas channels.  133  and gas sources  132  to deliver different concentrations or flow rates of a desired processing gas to the processing region  15 . The processing gasses may include inert gases, such as argon (Ar) or helium (He), and/or reactive gases that may be used for reactive sputtering processes, such as nitrogen (N 2 ), hydrogen (H 2 ) or oxygen (O 2 ). Since the density of the generated plasma during processing is related to the localized pressure in the processing region  15 , the gas flow and gas flow distribution into the processing region  15  can be controlled. In one aspect, a plurality of exit ports  134  spaced across the multizone target assembly  124  are used to deliver a desired gas distribution to the processing region  15 . In one aspect, a flow restrictor  138  is added in at least one of the gas channels  133  to control and balance the flow of the process gas through the plurality of exit ports  134 .  
         [0056]     In one aspect of the process gas delivery assembly  136 , as shown in  FIG. 7A , at least one gas channel  133  and at least one exit port  134  are adapted to deliver a processing gas to the processing region. 15  throughfa space  135  formed between the target sections (e.g., elements  127 A and  127 B). In one aspect, a plurality of exit ports  134  are uniformly spaced along the length of the gap “G” formed between at least two of the target sections to deliver a uniform gas flow into the processing region  15 .  FIG. 7B  illustrates a plan view of one embodiment of the multizone target assembly  124  that contains three target sections  127 A,  127 B and  127 C that have a plurality of exit ports  134  formed in the gaps “G” between the target sections (i.e., between  127 A and  127 B, and between  127 B and  127 C).  
         [0057]     In another aspect of the process gas delivery assembly  136 , one or more of the exit ports  134  are formed through the middle of at least one of the target sections (e.g., element  137  formed in  127 A).  FIG. 7C  illustrates a plan view of one embodiment of the multizone target assembly  124  that contains two target sections  127 A and  127 B, and one target section (element  127 A) has an exit port  134  that is adapted to deliver a process gas through the center (element “C”) of the target section by use of a gas source (not shown).  FIG. 7D  illustrates a plan view of one embodiment of the multizone target assembly  124  that has plurality of exit ports that are adapted to deliver a process gas to the processing region  15  through the target sections  127 A (element  134 A) and through the target sections  127 B (element  134 B) by use of one or more gas sources (not shown) connected to the exit ports (elements  134 A and  134 B).  
         [0058]     In one aspect, as shown in  FIG. 7A , the process gas delivery assembly  136  has at least two exit ports, where at least one exit port  134  is adapted to deliver gas through a region formed (element  137 ) in the middle of a target section and at least one exit port  134  is adapted to deliver the process gas through the gap “G” formed between at least two of the target sections. The various embodiments illustrated in FIGS.  7 A-D may be especially effective for use in a reactive sputtering process (e.g., TaN, TiN) since the process uniformity is related to uniformity of the reactive gas delivered to the processing region  15 . In this configuration it may be desirable to deliver reactive gases from a gas source  132  to the processing region  15  through a plurality of exit ports  134  that are evenly distributed across the multizone target assembly  124 .  
         [0059]     In one aspect, it is desirable to shape the edges of the target sections so that they overlap, as shown in  FIGS. 6 and 7 A, to in a sense hide the insulator  126  and bonded region  126 B from the plasma formed in the processing region  15 . Referring to  FIG. 7A , in one embodiment it may be useful to bevel the edges of the target sections near the region between them to form an overlapping feature which “hides” the bonded region  126 B. In one aspect, it may be desirable to remove all sharp edges of the target sections to reduce the current density emitted from these areas and thus make the electron emission and plasma generation more uniform in the processing region  15 .  
         [0060]      FIG. 1  illustrates one embodiment in which the target sections are positioned in one or more recesses in the insulator  126 . In this configuration the insulator protrusions  126 C formed in the insulator  126  are used to fill the gap(s) between the target regions. The use of the insulator protrusions  126 C can help to prevent the generation of a plasma between the target regions and electrically isolate the target regions. In one aspect, it may be desirable to add features (e.g., high aspect ratio trenches, recesses, overhangs) to the insulator protrusions  126 C to prevent any re-deposited target material from forming an arcing path between the target regions.  
         [0061]     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.