Patent Publication Number: US-2011053465-A1

Title: Method and apparatus for local polishing control

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of co-pending U.S. patent application Ser. No. 10/382,032, filed Mar. 4, 2003, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the invention generally relate to a method and apparatus for local polishing control in an electrochemical mechanical polishing system. 
     2. Background of the Related Art 
     Electrochemical mechanical polishing generally removes material from a semiconductor substrate through an electrochemical/chemical or a combined electrochemical/chemical and mechanical process. In one example of an electrochemical mechanical polishing system, a substrate or wafer is retained on a substrate support in a feature side up orientation. A polishing head having a conductive polishing pad and an internal counter electrode is placed in contact with the feature side of the substrate. The polishing head and the substrate are moved relative to one another in a predefined polishing motion. An electrolytic polishing fluid is disposed on the substrate and provides a conductive path between the substrate and the counter electrode. The substrate is electrically biased through the conductive pad relative to the counter electrode to drive a dissolution reaction at the substrate&#39;s surface to polish the substrate. 
     Copper is one material that may be polished using electrochemical mechanical polishing. Typically, copper is polished utilizing a two step process. In the first step, bulk of the copper is removed, typically leaving some copper residue projecting above the substrate&#39;s surface. The copper residue is then removed in a second or over-polishing step. 
     However, the removal of copper residue may result in dishing of copper features below the plane of surrounding material, typically an oxide or other barrier layer. The amount of dishing typically is related to polishing chemistries and processing parameter utilized in the over polish step, along with the width of the copper features subjected to polishing. As the copper layer does not have a uniform thickness across the substrate, it is difficult to removes all the copper residue without causing dishing over some features while not removing all of the copper residue over others. Thus, it would be advantageous if some areas of copper may be selectively polished while not polishing other areas to yield complete copper residue removal and minimized dishing. 
     Therefore, there is a need for a method and apparatus for local polishing control in an electrochemical mechanical polishing system. 
     SUMMARY OF THE INVENTION 
     A method and apparatus for local polishing control in a process cell is generally provided. In one aspect of the invention, an apparatus for electrochemically processing a substrate is provided that selectively processes discrete conductive portions of a substrate by controlling an electrical bias profile across a processing area, thereby controlling processing rates between two or more conductive portions of the substrate. 
     In another aspect of the invention, a method for electrochemically processing a substrate is provided that includes the steps of contacting conductive features disposed on a substrate with a conductive polishing pad assembly, flowing electrolyte between the conductive features and a first counter electrode, and selectively processing discrete portions of the conductive features. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that 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. 
         FIG. 1  is a sectional view of one embodiment of an electrochemical processing cell; 
         FIG. 2  is an exploded partial sectional view of the electrochemical processing cell of  FIG. 1 ; 
         FIGS. 3A-3C  depict various embodiments of an electrode assembly; 
         FIGS. 4A-4C  are simplified partial sectional views of a conductive pad and counter electrode assemblies illustrating a selective electrical bias profile; 
         FIGS. 5A-5C  are top views of various embodiments of conductive pad assemblies having different conductive element layouts; 
         FIG. 6  is a sectional view of another embodiment of an electrochemical processing cell; 
         FIG. 7  a simplified partial electrical schematic of the processing cell of  FIG. 6 ; 
         FIG. 8  is a sectional view of another embodiment of an electrochemical processing cell; 
         FIG. 9  a simplified partial electrical schematic of the processing cell of  FIG. 8 ; 
         FIG. 10  is a partial cross-sectional view of one embodiment of a polishing article; 
         FIG. 11  is a top plan view of one embodiment of a grooved polishing article; 
         FIG. 12  is a top plan view of another embodiment of a grooved polishing article; 
         FIG. 13  is a top plan view of another embodiment of a grooved polishing article; 
         FIG. 14A  is a top view of a conductive cloth or fabric described herein; 
         FIGS. 14B and 14C  are partial cross-sectional views of polishing articles having a polishing surface comprising a conductive cloth or fabric; 
         FIG. 14D  are partial cross-sectional views of one embodiment of a polishing article including a metal foil; 
         FIGS. 15A and 15B  are top and cross-section schematic views, respectively, of one embodiment of a polishing article having a conductive element; 
         FIGS. 15C and 15D  are top and cross-section schematic views, respectively, of one embodiment of a polishing article having a conductive element; 
         FIGS. 16A and 16B  are perspective views of other embodiments of a polishing article having a conductive element; 
         FIG. 17A  is a partial perspective view of another embodiment of a polishing article; 
         FIG. 17B  is a partial perspective view of another embodiment of a polishing article; 
         FIG. 17C  is a partial perspective view of another embodiment of a polishing article; 
         FIG. 17D  is a partial perspective view of another embodiment of a polishing article; 
         FIG. 17E  is a partial perspective view of another embodiment of a polishing article; 
         FIGS. 18A-18C  are schematic side views of one embodiment of a substrate contacting one embodiment of a polishing article described herein; 
         FIGS. 19A-19D  are top and side schematic views of embodiments of a polishing article having extensions connected to a power source; and 
         FIGS. 19E and 19F  show side schematic and exploded perspective views of another embodiment of providing power to a polishing article. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, wherever possible, to designate identical elements that are common to the figures. 
     DETAILED DESCRIPTION 
     The words and phrases used herein should be given their ordinary and customary meaning in the art by one skilled in the art unless otherwise further defined herein. Chemical-mechanical polishing should be broadly construed and includes, but is not limited to, abrading a substrate surface by chemical activity, mechanical activity, or a combination of both chemical and mechanical activity. Electropolishing should be broadly construed and includes, but is not limited to, planarizing a substrate by the application of electrochemical activity. Electrochemical mechanical polishing (ECMP) should be broadly construed and includes, but is not limited to, planarizing a substrate by the application of electrochemical/chemical activity, or a combination of both electrochemical/chemical and mechanical activity to remove material from a substrate surface. Electrochemical mechanical plating process (ECMPP) should be broadly construed and includes, but is not limited to, electrochemically depositing material on a substrate and concurrently planarizing the deposited material by the application of electrochemical activity, or a combination of both electrochemical and mechanical activity. 
     Anodic dissolution should be broadly construed and includes, but is not limited to, the application of an anodic bias to a substrate directly or indirectly which results in the removal of conductive material from a substrate surface and into a surrounding electrolyte solution. Aperture should be broadly construed and includes, but is not limited to, a perforation, hole, opening, groove, channel, or passage formed partially or completely through an object. Additionally, the term substantially, as used to modifying the term planar, is intended to describe a surface on a macroscopic or global level and not surface roughness. 
       FIG. 1  depicts a sectional view of one embodiment of a process cell  100  in which at least one process comprising anodic dissolution and polishing processes may be practiced. While the first embodiment of the invention is described for an electrochemical-mechanical polishing (ECMP) process that utilizes a configurable electrical bias profile for selective polishing across the surface of a substrate, the invention contemplates using the application of a configurable electrical bias profile in other fabrication processes involving electrochemical activity. Examples of such processes using electrochemical activity include electrochemical deposition, which involves the application of a bias profile to a substrate surface for selectively depositing a conductive material without the use of a conventional bias application apparatus, such as edge contacts, and electrochemical mechanical plating processes (ECMPP) that include a combination of electrochemical deposition and chemical mechanical polishing. 
     The process cell  100  generally includes a polishing head  102  and a basin  104  that houses a conductive pad assembly  122  and a counter electrode assembly  150 . A substrate  108 , typically having one or more conductive surfaces  140 , is retained in the polishing head  102  and lowered into the basin  104  during processing in a feature-down (e.g., backside up) orientation. The conductive surfaces  140  may include any one or combination of conductive material disposed in a feature, a layer of conductive material, or residue of conductive material remains on the substrate from a conductive layer. The substrate  108  and the conductive pad assembly  122  disposed in the basin  104  are moved relative to each other to provide a polishing motion. The polishing motion generally comprises at least one motion defined by an orbital, rotary, linear or curvilinear motion, or combinations thereof, among other motions. The polishing motion may be achieved by moving either or both of the polishing heads  102  and the basin  104 . The polishing head  102  may be stationary or driven to provide at least a portion of the relative motion between the basin  104  and the substrate  108  held by the polishing head  102 . Alternatively, the conductive pad assembly  122  may be moved, for example like a belt, while the polishing head  102  is stationary or in motion. In the embodiment depicted in  FIG. 1 , the polishing head  102  is coupled to a drive system  110 . The drive system  110  moves the polishing head  102  with at least one of a rotary, orbital, sweep motion or combinations thereof. 
     In one embodiment, the polishing head  102  includes a housing  114  enclosing a bladder  116 . The bladder  116  may be deflated when contacting the substrate to create a vacuum therebetween, thus securing the substrate to the polishing head  102 . The bladder  116  may additionally be inflated to press the substrate in contact with the conductive pad assembly  122  retained in the basin  104 . A retaining ring  138  is coupled to the housing  114  and circumscribes the substrate  108  to prevent the substrate from slipping out from the polishing head  102  while processing. One polishing head that may be adapted to benefit from the invention is a TITAN HEAD™ carrier head available from Applied Materials, Inc., located in Santa Clara, Calif. Another example of a polishing head that may be adapted to benefit from the invention is described in U.S. Pat. No. 6,159,079, issued Dec. 12, 2001, which is hereby incorporated herein by reference in its entirety. 
     The basin  104  is generally fabricated from a non-conductive material that is compatible with electroplating and/or electropolishing chemistries. The basin  104  includes a bottom  144  and sidewalls  146  that define a container that houses the conductive pad assembly  122  and the electrode assembly  150 . The sidewalls  146  of the basin  104  are configured to retain electrolyte that makes conductive contact with the electrode assembly  150  and the substrate held by the polishing head  102  against the conductive pad assembly  122 . The sidewalls  146  include a port  118  formed therethrough to allow removal of electrolyte from the basin  104 . The port  118  is coupled to a valve  120  to selectively drain or retain the electrolyte in the basin  104 . 
     The basin  104  is rotationally supported above a base  106  by bearings  134 . A drive system  136  is coupled to the basin  104  and rotates the basin  104  during processing. A catch basin  128  is disposed on the base  106  and circumscribes the basin  104  to collect processing fluids, such as the electrolyte, that flow out of port  118  disposed through the basin  104  during and/or after processing. 
     An electrolyte delivery system  132  is generally disposed adjacent the basin  104  and is adapted to provide electrolyte to the basin  104 . The electrolyte disposed in the basin  104  creates a conductive path between the counter electrode assembly  150  and conductive pad assembly  122  through the substrate&#39;s surface when the substrate  108  is in contact with the conductive pad assembly  122 . The electrolyte delivery system  132  includes a nozzle or outlet  130  coupled to an electrolyte source  142 . The outlet  130  flows electrolyte or other processing fluid from the electrolyte source  142  into the basin  104 . During processing, the electrolyte generally provides an electrical path for biasing the substrate  108  and driving an electro-chemical process to remove material from the substrate  108 . 
     Electrolytes for copper containing material removal generally include inhibitors, chelating agents and pH adjusting agents. One electrolyte that can be used for electrochemical removal of metals from the substrate  108  is described in U.S. patent application Ser. No. 10/032,075, filed Dec. 21, 2001, which is hereby incorporated by reference in its entirety. 
     A multiple-output power source  124  is coupled to the counter electrode assembly  150  and conductive pad assembly  122  by electrical leads  112  (shown as  112 A i -B, where i is a positive integer greater than 1). The power source  124  applies an electrical bias between the counter electrode assembly  150  and the conductive pad assembly  122 . The bias applied by each output of the power source  124  coupled to each of the leads  112 Ai is independently controllable in magnitude, and typically may range between 0 to about 5 Volts DC. When the conductive pad assembly  122  is in contact with the substrate  108  in the presence of the electrolyte, the potential provided by the power source  124  drives an electrochemical process as described further below. 
     The leads  112  are routed through a slip ring  126  disposed below the basin  104 . The slip ring  126  facilitates continuous electrical connection between the power source  124 , electrode assembly  150  and the conductive pad assembly  122  as the basin  104  rotates. The leads  112  are wires, tapes or other conductors compatible with process fluids or having a covering or coating that protects the leads  112  from the process fluids. Examples of materials that may be utilized in the leads  112  include insulated graphite, titanium, platinum, gold, and HASTELOY® among other materials. Coatings disposed around the leads  112  may include polymers such as fluorocarbons, PVC, polyamide, and the like. 
     The conductive pad assembly  122  is coupled to the lead  112 B that is routed (with leads  112 A i  that is coupled to the counter electrode assembly  150 ) through the bottom  144  of the basin  104  to the power source  124 . The lead  112 B may by coupled to the conductive pad assembly  122  by any number of methods that facilitate good electrical connection between the conductive pad assembly  122  and the power source  124 , for example, by soldering, stacking, brazing, clamping, crimping, riveting, fastening, conductive adhesive or by other methods or devices that facilitate good electrical connection between the lead  112 B and the conductive pad assembly  122 . Optionally, the leads  112 A i -B may be coupled to the power source  124  using a single disconnect  266  (as shown in  FIG. 2 ), disposed in the basin  104 , to further facilitate replacement of either the conductive pad assembly  122  or counter electrode assembly  150 . 
     The conductive pad assembly  122  includes a top pad  170  having a plurality of conductive elements  172 , and an optional sub-pad  174 . The sub-pad  174  is disposed between top pad  170  and the counter electrode assembly  150 . 
     A controller  180  is coupled to the processing cell  100  to facilitate control of the voltages applied between the pad assembly  122  and the counter electrode assembly  150  by the power source  124 . The controller  180  typically includes a central processing unit (CPU)  182 , support circuits  186  and memory  184 . The CPU  182  may be one of any form of computer processor that can be used in an industrial setting for controlling various subprocessors, substrate processing and cell functions. The memory  184  is coupled to the CPU  182 . The memory  184 , or computer-readable medium, may be one or more of 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. The support circuits  186  are coupled to the CPU  182  for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry, subsystems, and the like. 
       FIG. 2  depicts an exploded sectional view of one embodiment of the conductive pad assembly  122  and counter electrode assembly  150  that is removably disposed in the basin  104  of  FIG. 1 . The conductive pad assembly  122  depicted in  FIG. 2  includes the top pad  170  coupled to the sub-pad  174 . The sub-pad  174  is disposed on or coupled to the counter electrode assembly  150 . 
     The top pad  170  is typically fabricated from polymeric materials compatible with process chemistry, examples of which include polyurethane, polycarbonate, fluoropolymers, PTFE, PTFA, polyphenylene sulfide (PPS), or combinations thereof, and other polishing materials used in polishing substrate surfaces. The top pad  170  may also contain fillers and/or be foamed. Exemplary conventional material includes those made from polyurethane and/or polyurethane mixed with fillers, which are commercially available from Rodel, Inc., headquartered in Phoenix, Ariz. Other conventional polishing materials, such as a layer of compressible material, may also be utilized for the top pad  170 . Compressible materials include, but are not limited to, soft materials such as compressed felt fibers leached with urethane or foam. The top pad  170  is generally between about 10 to about 100 mils thick. 
     The top pad  170  has a first side  208  and a second side  210 . The first side  208  is adapted to contact the substrate  108  (shown in  FIG. 1 ) during processing. The first side  208  may include grooves, embossing or other texturing to promote polishing performance. The top pad  170  may be solid, impermeable to electrolyte, permeable to electrolyte or perforated. In the embodiment depicted in  FIG. 2 , the top pad  170  is perforated with a plurality of apertures  212  adapted to allow flow of electrolyte therethrough. The first side  208  additionally includes one or more slots  264  or other feature that retains the conductive elements  172  therein. 
     The conductive elements  172  may include conductive polymers, polymer composites with conductive materials, conductive metals or polymers, conductive fillers, graphitic materials, or conductive doping materials, or combinations thereof. The conductive elements  172  generally have a bulk resistivity or a bulk surface resistivity of about 10 Ω-cm or less. 
     In the embodiment depicted in  FIG. 2 , the conductive elements  172   A  are a plurality of electrically conductive fibers, stands and/or flexible fingers, such as carbon fibers or other conductive, compliant (i.e., flexible) material that facilitate electrical contact with the substrate while processing. In an alternative embodiment, the conductive elements  172   B  may be rollers, balls, rods, bars, mesh or other shape that facilitates conductive contact between the substrate disposed on the top pad  170  and the power source  124 . In yet another alternative embodiment, the conductive elements  172   C  may be rollers, balls, rods, bars, mesh or other shape seated in a conductive carrier  224  that facilitates conductive contact between the substrate disposed on the top pad  170  and the power source  124 . 
     Other types/configurations of conductive elements that may be utilized include tubing, springs, wire, tape, brushes, bars, mesh, cylinders, balls and pins. Examples of conductive pads that may be adapted to benefit from the invention are described in U.S. Provisional Patent Application Ser. No. 60/342,281, filed Dec. 19, 2001; U.S. Provisional Patent Application Ser. No. 60/326,263, filed Oct. 1, 2001; U.S. Provisional Patent Application Ser. No. 60/286,107, filed Apr. 24, 2001; U.S. patent application Ser. No. 10/140,010, filed May 7, 2002; and U.S. patent application Ser. No. 10/033,732, filed Dec. 27, 2001, all of which are incorporated herein by reference in their entireties. The conductive elements  172  may alternatively be intermixed in the top pad  170  to form a unitary body. 
     The sub-pad  174  is coupled to the second side  210  of the top pad  170 . The sub-pad  174  is typically fabricated from a material softer, or more compliant, than the material of the top pad  170 . The difference in hardness or durometer between the top pad  170  and the sub-pad  174  may be chosen to produce a desired polishing/plating performance. The sub-pad  174  may also be compressive. Examples of suitable backing materials include, but are not limited to, foamed polymer, elastomers, felt, impregnated felt and plastics compatible with the polishing chemistries. 
     The sub-pad  174  has a first side  214  and a second side  216 . The first side  214  is coupled to the second side  210  of the top pad  170 . The sub-pad  174  typically has a thickness in the range of about 5 to about 100 mils, and in one embodiment, is about 5 mils thick. The sub-pad  174  may be solid, impermeable to electrolyte, permeable to electrolyte or perforated. In one embodiment depicted in  FIG. 2 , the sub-pad  174  is configured to allow electrolyte therethrough, and may be permeable, have holes formed therethrough or a combination thereof. In the embodiment depicted in  FIG. 2 , the sub-pad  174  is perforated with a plurality of apertures  218  adapted to allow flow of electrolyte therethrough. The apertures  218  of the sub-pad  174  typically, but not necessarily, align with the apertures  212  of the top pad  170 . 
     The counter electrode assembly  150  may be solid, impermeable to electrolyte, permeable to electrolyte, or perforated. The counter electrode assembly  150  has a first side  220  and a second side  222 . The first side  220  of the counter electrode assembly  150  is coupled to the second side  216  of the sub-pad  174 . In the embodiment depicted in  FIG. 2 , the counter electrode assembly  150  is configured to allow electrolyte therethrough. The counter electrode assembly  150  may be permeable, have holes formed therethrough or a combination thereof. 
     The second side  222  of the counter electrode assembly  150  may be adhered to the bottom  144  of the basin  104  with a removable adhesive to prevent the counter electrode assembly  150  from moving during polishing while allowing the counter electrode assembly  150  to be replaced. The counter electrode assembly  150  may alternatively be clamped, fastened or secured to the basin  104  by other methods. 
     The counter electrode assembly  150  may be a singular component or element, or part of a prefabricated assembly with the conductive pad assembly  122 . One example of an electrode and conductive pad assembly that may be adapted to benefit from the invention is described in U.S. patent application Ser. No. 10/151,538, filed May 16, 2002, which is hereby incorporated by reference in its entirety. 
     In one embodiment, the counter electrode assembly  150  is fabricated from a plurality of electrodes  260   i , spaced by one or more insulators  262 . At least one of the electrode  260   i  or insulators  262  is configured to allow electrolyte through the counter electrode assembly  150 . The one or more insulators  262  are disposed between the electrodes  260   i  to electrically isolate the electrodes  260   i  from one another. The insulators  262  may be fabricated from any dielectric material suitable for use with process chemistries. The insulators  262  may be in the form of a web, egg-crate or other structure suitable for providing lateral electrical isolation between the electrodes  260   i . 
     In the embodiment depicted in  FIG. 2 , the electrodes  260   i  are disposed in or embedded in the insulator  262 . The electrodes  260   i  are typically comprised of the material to be deposited or removed, such as copper, aluminum, gold, silver, tungsten and other materials which can be electrochemically deposited on the substrate  108 . For electrochemical removal processes, such as anodic dissolution, the electrodes  260   i  may include a electrode of a material other than the deposited material. The electrodes  260   i  may range in thickness from foils to greater than 100 mils thick. 
       FIGS. 3A-C  depict various embodiments of the electrodes  260   i  and insulators  262 . In the embodiment depicted in  FIG. 3A , the electrodes  260   i  are cylinders having a passage  302  disposed therethrough that allows passage of electrolyte through the counter electrode assembly  150 . In the embodiment depicted in  FIG. 3B , the electrodes  260   i  are disposed in the insulator  262  that has a plurality of apertures  304  formed therethrough that allows passage of electrolyte through the counter electrode assembly  150 . In the embodiment depicted in  FIG. 3C , at least one of the electrodes  260   i  or insulator  262  are at least one of perforated or permeable to electrolyte thereby allowing electrolyte through the counter electrode assembly  150  during processing. 
     Returning to  FIG. 2 , each of the electrodes  260   i  (where i is a positive integer greater than 1, of which five are shown in  FIG. 2 ) are coupled independently by the leads  112 A i  to the power source  124 , thereby allowing each electrode  260   i  to be biased independently, and, when appropriate, at a different level than one of the other electrodes  260   i . For example, an electrode  260   1  may be biased to a voltage level greater than an electrode  260   2 . The independent biasing of the electrodes  260   i  allows the substrate to be polished selectively at different rates across the diameter of the substrate. 
       FIG. 4A  is a simplified partial sectional view of the counter electrode assembly  150  illustrating a selective electrical bias profile. The substrate  108  having a first conductive surface  402  and a second conductive surface  404  is depicted in contact with the conductive pad assembly  122 . The conductive surfaces  402 ,  404  may be portions of a single conductive feature, or separate structures or residue of conductive material remains on the substrate from a conductive layer. In the embodiment depicted in  FIG. 4A , the first conductive surface  402  and the second conductive surface  404  are at different elevations relative to a reference surface  406  of the substrate  108 , with the first conductive surface  402  extends farther from the reference surface  406  than the second conductive surface  404 . It is contemplated that the first conductive surface  402  and/or the second conductive surface  404  may be recessed from the reference surface  406 . 
     In order to polish the first conductive surface  402  and the second conductive surface  404  to a common plane (typically defined by the reference surface  406 ), a first voltage is applied to the electrode  260   1  while a second voltage is applied to the electrode  260   2 . It is contemplated that the first conductive surface  402  may represent residue from a layer of conductive material and that, as a result of the localized polishing, the first conductive surface  402  is removed to expose the underlying reference surface  406 . If the first voltage is less than the second voltage, resulting in a greater current density between the electrode  260   2  and the conductive pad assembly  122 , which causes the first conductive surface  402  to be polished at a faster rate than the second conductive surface  404 . Conversely, more voltage may be applied to the electrode  260   1 , which causes the second conductive surface  404  to be polished faster than the first conductive surface  402 . 
     Control of the polishing rates is facilitated by a plurality of sensors  408   i  that detect the desirability to polish the surfaces  402 ,  404  differently. In the embodiment depicted in  FIG. 4A , the sensors  408   i  (illustratively shown as sensor  408   1  and sensor  408   2 ) are current sensors disposed between the electrodes  260   i  and the power source  124 . As the distance between the elements  402 ,  404  and the electrode assembly  150  influences the current flux across that gap, current flow at each location (i.e., at elements  402 ,  404 ) is indicative of the elevation of each feature  402 ,  404  relative to the electrode assembly  150  and reference plane  406  of the substrate  108 . Alternatively, the sensors  408   i  may be voltage sensors or other sensors capable of detecting heights of the surfaces  402 ,  404  to the reference plane  406 . 
     Each sensor  408   i  is coupled to the controller  180  to provide feed back as to the topography of the conductive surfaces of the substrate  108 . As the substrate  108  is moved in relation to the conductive pad assembly  122  during processing, the sensors  408   i  update the relative position of each conductive surface across the width of the substrate  108 . The controller  180 , in response to information provided by the sensors  408   i , causes the power source  124  to independently provide predetermined voltages to each of the electrode  260   i  at a magnitude corresponding to a desired polishing rate that the locations of the substrate  108  disposed in contact with a particular conductive elements  172  associated with the sensors  408   i  at that instant in time. Thus, the bias profile of the conductive pad assembly  122  may be continually adjusted to polish by anodic dissolution faster at substrate locations having conductive topography at higher elevations relative to the reference plane  406  of the substrate, advantageously polishing conductive topography at lower elevations at a slower rate, thus improving polishing performance and minimizing dishing. 
     It is also contemplated, for example in embodiments where the first conductive surface  402  is recessed from the reference surface  406 , the power source  124  may bias the first conductive surface  402  with a polarity that results in deposition of conductive material from the electrolyte and/or electrode thereon. Deposition may occur at the first conductive surface  402  while also depositing material on the second conductive surface  404  or removing material from the second conductive surface  404 . 
     In another mode of operation depicted in  FIG. 4B , the sensors  408   i  may be utilized to detect differences in the exposed area of surfaces  452 ,  454  relative to the reference plane defined by the surface  406 . For example, the first conductive surface  452  being an exposed surface of a filled feature will have a current flux greater than the second conductive surface  454  that is residue from the conductive layer  450  (shown in phantom) being removed. As the surface area of the second conductive surface  454  decreases, the current flux decreases ultimately to approximately zero, indicating the removal of the second conductive surface  454  (e.g., the residue) from the surface  406 . 
     In another mode of operation depicted in  FIG. 4C , a sensor  470  may be utilized to detect differences in the exposed area of surfaces  472 ,  474  relative to the reference plane defined by the surface  406 . The sensor  470  is configured to detect the amount of reflectivity between the surfaces  406 ,  472  and  474 . The sensor  470  generally generates a beam of light that passes through a window  478  formed in the polishing surface. The beam reflects off the substrate and back to the sensor  470 , wherein the intensity of the reflected beam is indicative of the composition of the substrate. For example, the first conductive surface  472  being an exposed surface of a filled feature, which is typically one of a repeating number of feature formed across the width of the substrate, will have a greater reflectivity than the second conductive surface  474  that is residue from the conductive layer  476  (shown in phantom) being removed. Thus, differences in the amount of reflected light from the substrate is indicative of areas having features and residue. As the surface area of the second conductive surface  474  decreases, the current flux decreases ultimately to approximately zero, indicating the removal of the second conductive surface  474  from the surface  406 . 
       FIGS. 5A-C  are top views of various embodiments of counter electrode assemblies having different conductive element layouts. It is contemplated that the electrodes may be configured in any number of orientations on the counter electrode assembly to facilitate control over the bias profile so that discrete portions of the substrate may be selectively polished as the substrate moves relative to the conductive pad and counter electrode assemblies. 
       FIG. 5A  is a top view of one embodiment of a counter electrode assembly  500 A. The counter electrode assembly  500 A includes a plurality of electrodes  504   i  that are adapted to electrically drive processing of discrete conductive portions of the substrate. The electrodes  504   i  are arranged in a grid pattern across a top surface  502  of the counter electrode assembly  500 A and may be selectively energized with a predetermined voltage level to control the local polishing rates on the substrate. 
       FIG. 5B  is a top view of one embodiment of a counter electrode assembly  500 B. The counter electrode assembly  500 B includes a plurality of electrodes  514   i  that are arranged in a radial pattern on a top surface  512  of the counter electrode assembly  500 B. The radial pattern of electrodes  514   i  may comprise concentric rings of electrodes  514   i . Each ring may be configured from a single or a plurality of electrodes  514   i  that may be selectively energized with a predetermined voltage level to control the local polishing rates on the substrate. 
       FIG. 5C  is a top view of one embodiment of a counter electrode assembly  500 C. The counter electrode assembly  500 C includes a plurality of electrodes  524   i  that are arranged in a polar array on a top surface  522  of the counter electrode assembly  500 C. The electrodes  524   i  may be selectively energized with a predetermined voltage level to control the local polishing rates on the substrate. Other arrangements of electrodes  524   i  are also contemplated. 
       FIG. 6  is another embodiment of a process cell  600  in which at least one process comprising anodic dissolution and polishing process may be practiced. The process cell  600  generally includes a polishing head  602 , conductive pad assembly  606  and a basin  604  that houses a conductive pad assembly  606 , an electrode assembly  614  and a counter electrode assembly  608 . The polishing head  602  and the basin  604  are generally similar to the polishing head  102 , conductive pad assembly  122  and the basin  104  described above. An electrolyte delivery system  132  provides electrolyte to the basin  604  during processing. 
     The conductive pad assembly  606  and the counter electrode assembly  608  are coupled to a first power source  610  by electrical leads  612 A-B. The first power source  610  applies an electrical bias between the counter electrode assembly  608  and the conductive pad assembly  606 . The bias applied across the pad and counter electrode assemblies  606 ,  608  typically ranges between 0 to about 5 Volts DC. When the conductive pad assembly  606  is in contact with a substrate  108  in the presence of the electrolyte, the potential provided by the first power source  610  drives an electrochemical process as described further below. 
     The electrode assembly  614  disposed between the pad assembly  606  and the counter electrode assembly  608 . The electrode assembly  614  is configured to allow the electrolyte to move between the pad assembly  606  and the counter electrode assembly  608  so that the electrolyte establishes a conductive path between a substrate  630  disposed on the pad assembly  606  and the counter electrode assembly  608 . 
     The electrode assembly  614  is comprised of a plurality of independently biasable electrodes  616   i  laterally insulated from each other by one or more dielectric members  618 . The electrodes  616   i  may be consumable or non-consumable and may be fabricated from materials similar to those identified as suitable for the counter electrodes discussed above. The dielectric member  618  is typically formed from a material compatible with process chemistries and of sufficient dielectric strength to laterally isolate the electrodes  616   i  at process voltages. 
     At least one of the electrodes  616   i  or the dielectric member  618  is porous, perforated, permeable or otherwise configured to allow passage of the electrolyte therethrough. Alternatively, the electrodes  616   i  and the dielectric member  618  may be arranged to define passages that allow the electrolyte through the electrode assembly  614 . 
     A multiple-output power source  620  is coupled respectively by leads  622   i  to each of the electrodes  616   i . The power source  620  allows each of the electrodes  616   i  to be independently biased to control a local polishing rate adjacent each electrode  616   i  by increasing (or decreasing) the current flux at surface of the substrate adjacent the respective electrode  616   i . 
       FIG. 7  is a simplified partial electrical schematic of the process cell  600 . The substrate  630  is shown having a first conductive feature  702  and a second conductive feature  704 . The conductive features  702 ,  704  are electrically coupled to the first power source  610  by the conductive pad assembly  606  (not shown in  FIG. 7 ) and biased relative to the counter electrode assembly  608 . 
     A first conductive path  710   1  is defined through the electrolyte disposed between the first conductive feature  702  and the counter electrode assembly  608 . The first conductive path  710   1  is comprised of two circuit branches  706   1 ,  708   1 . The amount of current flowing through the first branch  706   1  of the first conductive path  710   1  is controlled in part by the potential applied by the first power source  610 . The current flowing through the first branch  706   1  of the first conductive path  710   1  is regulated in response to a voltage applied by the second power source  620  to the first electrode  616   1  that is disposed between the first conductive feature  702  and the counter electrode assembly  608  (the electrodes are shown offset for clarity of the schematic of  FIG. 7 ). As the electrode  616   1  become biased with a voltage of same polarity and approaching (or exceeding) the potential of the first conductive feature  702  relative to the counter electrode assembly  806 , the amount of current flowing between the first conductive feature  702  and the counter electrode assembly  608  through the first branch  706   1  decreases, thus slowing the rate of material removal from the first conductive feature  702 . Conversely, as the bias of the reference electrode  616   1  becomes more disparate compared to the potential of the first conductive feature  702  relative to the counter electrode assembly  806 , the amount of current flowing between the first conductive feature  702  and the counter electrode assembly  608  through the first branch  706   1  increase, thus increasing the rate of material removal from the first conductive feature  702 . 
     A second conductive path  710   2  is similarly configured having of a first circuit branch  706   2  and a second circuit branch  708   2 . The amount of current flowing through the first branch  706   2  of the second conductive path  710   2  is controlled in part by the potential applied by the first power source  610 . The current flowing through the second branch  706   2  of the second conductive path  710   2  is regulated in response to a voltage applied to the second electrode  616   2  by the second power source  620 . As the second power source  620  independently controls the voltage to each electrode  616   i , the current flowing through the first branch  706   i  of each conductive path  710   i  may be tailored to independently control the relative rate of material removal from each conductive feature disposed across the width of the substrate  630 . 
       FIG. 8  is another embodiment of a process cell  800  for processing a substrate  814  configured similar to the process cell  600  described above, except that the process cell  800  includes a counter electrode assembly  802  and a plurality of electrodes  804   i  coupled to a power source  806 . In one embodiment, the power source  806  is potentiostat, such as those available from Princeton Applied Research, that allows each of the electrodes  804   i  to be independently biased relative to counter electrode assembly  802 . Thus, the power source  806  may apply a potential to the electrodes  804   i  that controls the local current flow along each of the conductive paths formed between the conductive features of the substrate and the counter electrode assembly  802 , thereby allowing control of the polishing rate across the diameter of the substrate. Optionally, sensors (not shown) may be utilized as described above to facilitate closed loop control of substrate processing. 
       FIG. 9  is a simplified partial electrical schematic of the process cell  800 . The substrate  814  is shown having a first conductive feature  902  and a second conductive feature  904 . The conductive features  902 ,  904  are electrically coupled to the first power source  806  by the conductive pad assembly  606  (shown in  FIG. 8 ) and biased relative to the counter electrode assembly  802 . 
     A first conductive path  910   1  is defined through the electrolyte disposed between the first conductive feature  902  and the first counter electrode  804   1  of the counter electrode assembly  802 . The first conductive path  910   1  is comprised of two circuit branches  906   1 ,  908   1 . The amount of current flowing through the first branch  906   1  of the first conductive path  910   1  is controlled in part by the potential applied by the first power source  806 . As each counter electrode  804   i  is independently controlled, the contribution to current flowing between the conductive features of the substrate  814  may be controlled across the width of the substrate. The current flowing through the first branch  906   1  of the first conductive path  910   1  is further regulated in response to a voltage applied by a second multiple output power source  620  to the first electrode  616   1  as discussed above. 
     A second conductive path  910   2  is similarly configured having of a first circuit branch  906   2  and a second circuit branch  908   2 . The amount of current flowing through the first branch  906   2  of the second conductive path  910   2  is further controlled in part by the potential applied by the first power source  806 . The current flowing through the second branch  906   2  of the second conductive path  910   2  is regulated in response to a voltage applied to the second electrode  616   2  by the second power source  620 . As the second power source  620  independently controls the voltage to each electrode  616   i , the current flowing through the first branch  906   i  of each conductive path  910   i  may be further tailored to independently control the relative rate of material removal from each conductive feature disposed across the width of the substrate  814 . 
     Closed loop control of the processing is facilitated by a plurality of sensors  912   i , one of which respectively coupled between each of the counter electrodes  804   i  and the first power source  806 . The sensors  912   i  are coupled to a controller  180  and are configured to provide a metric indicative of the relative heights between respective conductive features positioned in series with a respective sensor  912   i . Thus, in response to the metric provided by each of the sensors  912   i , the controller  180  can vary the potential applied to each electrode  616   i  and/or each counter electrode  804   i  to control the rate of material removal across the width of the substrate  814 . 
       FIGS. 10-19F  depict various embodiments of a polishing article as previously incorporated from Ser. No. 10/140,010, now U.S. Pat. No. 6,979,248.  FIG. 10  is a partial cross-sectional view of one embodiment of a polishing article  1005 . Polishing article  1005  illustrated in  FIG. 10  comprises a composite polishing article having a conductive polishing portion  1010  for polishing a substrate surface and an article support, or sub-pad, portion  1020 . 
     The conductive polishing portion  1010  may comprise a conductive polishing material including the conductive fibers and/or conductive fillers as described herein. For example, the conductive polishing portion  1010  may include a conductive material comprising conductive fibers and/or conductive fillers dispersed in a polymeric material. Further, the conductive polishing portion may include one or more loops, coils, or rings of conductive fibers, or conductive fibers interwoven to form a conductive fabric or cloth. The conductive polishing portion  1010  may also be comprised of multiple layers of conductive materials, for example, multiple layers of conductive cloth or fabric. 
     One example of the conductive polishing portion  1010  includes gold coated nylon fibers and graphite particles disposed in polyurethane. Another example includes graphite particles and/or carbon fibers disposed in polyurethane or silicone. 
     The article support portion  1020  generally has the same or smaller diameter or width of the conductive polishing portion  1010 . However, the invention contemplates the article support portion  1020  having a greater width or diameter than the conductive polishing portion  1010 . While the figures herein illustrate a circular conductive polishing portion  1010  and article support portion  1020 , the invention contemplates that the conductive polishing portion  1010 , the article support portion  1020 , or both may have different shapes such as rectangular surfaces or elliptical surfaces. The invention further contemplates that the conductive polishing portion  1010 , the article support portion  1020 , or both, may form a linear web or belt of material. 
     The article support portion  1020  may comprise inert materials in the polishing process and are resistant to being consumed or damaged during ECMP. For example, the article support portion may be comprised of a conventional polishing materials, including polymeric materials, for example, polyurethane and polyurethane mixed with fillers, polycarbonate, polyphenylene sulfide (PPS), ethylene-propylene-diene-methylene (EPDM), Teflon™ polymers, or combinations thereof, and other polishing materials used in polishing substrate surfaces. The article support portion  1020  may be a conventional soft material, such as compressed felt fibers impregnated with urethane, for absorbing some of the pressure applied between the polishing article  1005  and the carrier head  130  during processing. The soft material may have a Shore A hardness between about 20 and about 90. 
     Alternatively, the article support portion  1020  may be made from a conductive material compatible with surrounding electrolyte that would not detrimentally affect polishing including conductive noble metals or a conductive polymer, to provide electrical conduction across the polishing article. Examples of noble metals include gold, platinum, palladium, iridium, rhenium, rhodium, rhenium, ruthenium, osmium, and combinations thereof, of which gold and platinum are preferred. Materials that are reactive with the surrounding electrolyte, such as copper, may be used if such materials are isolated from the surrounding electrolyte by an inert material, such as a conventional polishing material or a noble metal. 
     When the article support portion  1020  is conductive, the article support portion  1020  may have a greater conductivity, i.e., lower resistivity, than the conductive polishing portion  1010 . For example, the conductive polishing portion  1010  may have a resistivity of about 1.0 Ω-cm or less as compared to an article support portion  1020  comprising platinum, which has a resistivity 9.81 Ω-cm at 0° C. A conductive article support portion  1020  may provide for uniform bias or current to minimize conductive resistance along the surface of the article, for example, the radius of the article, during polishing for uniform anodic dissolution across the substrate surface. A conductive article support portion  1020  may be coupled to a power source for transferring power to the conductive polishing portion  1010 . 
     Generally, the conductive polishing portion  1010  is adhered to the article support portion  1020  by a conventional adhesive suitable for use with polishing materials and in polishing processes. The adhesive may be conductive or dielectric depending on the requirements of the process or the desires of the manufacturer. The article support portion  1020  may be affixed to a support, such as disc, by an adhesive or mechanical clamp. Alternatively, if polishing article  1005  only includes a conductive polishing portion  1010 , the conductive polishing portion may be affixed to a support, such as disc, by an adhesive or mechanical clamp. 
     The conductive polishing portion  1010  and the article support portion  1020  of the polishing article  1005  are generally permeable to the electrolyte. A plurality of perforations may be formed, respectively, in the conductive polishing portion  1010  and the article support portion  1020  to facilitate fluid flow therethrough. The plurality of perforations allows electrolyte to flow through and contact the surface during processing. The perforations may be inherently formed during manufacturing, such as between weaves in a conductive fabric or cloth, or may be formed and patterned through the materials by mechanical means. The perforations may be formed partially or completely through each layer of the polishing article  1005 . The perforations of the conductive polishing portion  1010  and the perforations of the article support portion  1020  may be aligned to facilitate fluid flow therethrough. 
     Examples of perforations  1050  formed in the polishing article  1005  may include apertures in the polishing article having a diameter between about 0.02 inches (0.5 millimeters) and about 0.4 inches (10 mm). The thickness of the polishing article  1005  may be between about 0.1 mm and about 5 mm. For example, perforations may be spaced between about 0.1 inches and about 1 inch from one another. 
     The polishing article  1005  may have a perforation density between about 20% and about 80% of the polishing article in order to provide sufficient mass flow of electrolyte across the polishing article surface. However, the invention contemplates perforation densities below or above the perforation density described herein that may be used to control fluid flow therethrough. In one example, a perforation density of about 50% has been observed to provide sufficient electrolyte flow to facilitate uniform anodic dissolution from the substrate surface. Perforation density is broadly described herein as the volume of polishing article that the perforations comprise. The perforation density includes the aggregate number and diameter or size of the perforations, of the surface or body of the polishing article when perforations are formed in the polishing article  1005 . 
     The perforation size and density is selected to provide uniform distribution of electrolyte through the polishing article  1005  to a substrate surface. Generally, the perforation size, perforation density, and organization of the perforations of both the conductive polishing portion  1010  and the article support portion  1020  are configured and aligned to each other to provide for sufficient mass flow of electrolyte through the conductive polishing portion  1010  and the article support portion  1020  to the substrate surface. 
     Grooves may be disposed in the polishing article  1005  to promote electrolyte flow across the polishing article  1005  to provide effective or uniform electrolyte flow with the substrate surface for anodic dissolution or electroplating processes. The grooves may be partially formed in a single layer or through multiple layers. The invention contemplates grooves being formed in the upper layer or polishing surface that contacts the substrate surface. To provide increased or controlled electrolyte flow to the surface of the polishing article, a portion or plurality of the perforations may interconnect with the grooves. Alternatively, the all or none of the perforations may interconnect with the grooves disposed in the polishing article  1005 . 
     Examples of grooves used to facilitate electrolyte flow include linear grooves, arcuate grooves, annular concentric grooves, radial grooves, and helical grooves among others. The grooves formed in the article  1005  may have a cross-section that is square, circular, semi-circular, or any other shape that may facilitate fluid flow across the surface of the polishing article. The grooves may intersect each other. The grooves may be configured into patterns, such as an intersecting X-Y pattern disposed on the polishing surface or an intersecting triangular pattern formed on the polishing surface, or combinations thereof, to improve electrolyte flow over the surface of the substrate. 
     The grooves may be spaced between about 30 mils and about 300 mils apart from one another. Generally, grooves formed in the polishing article have a width between about 5 mils and about 30 mils, but may vary in size as required for polishing. An example of a groove pattern includes grooves of about 10 mils wide spaced about 60 mils apart from one another. Any suitable groove configuration, size, diameter, cross-sectional shape, or spacing may be used to provide the desired flow of electrolyte. Additional cross sections and groove configurations are more fully described in co-pending U.S. Patent Provisional Application Ser. No. 60/328,434, filed on Oct. 11, 2001, entitled “Method And Apparatus For Polishing Substrates”, which is incorporated herein by reference to the extent not inconsistent with the claims and disclosure herein. 
     Electrolyte transport to the surface of the substrate may be enhanced by intersecting some of the perforations with the grooves to allow electrolyte to enter through one set of perforation, be evenly distributed around the substrate surface by the grooves, used in processing a substrate, and then processing electrolyte is refreshed by additional electrolyte flowing through the perforations. An example of a pad perforation and grooving is more fully described in U.S. patent application Ser. No. 10/026,854, filed Dec. 20, 2001, which is incorporated by reference to the extent not inconsistent with the aspects and claims herein. 
     Examples of polishing articles having perforations and grooves are as follows.  FIG. 11  is a top plan view of one embodiment of a grooved polishing article. A round pad  1140  of the polishing article  1005  is shown having a plurality of perforations  1146  of a sufficient size and organization to allow the flow of electrolyte to the substrate surface. The perforations  1146  can be spaced between about 0.1 inches and about 1 inch from one another. The perforations may be circular perforations having a diameter of between about 0.02 inches (0.5 millimeters) and about 0.4 inches (10 mm). Further the number and shape of the perforations may vary depending upon the apparatus, processing parameters, and ECMP compositions being used. 
     Grooves  1142  are formed in the polishing surface  1148  of the polishing article  1005  therein to assist transport of fresh electrolyte from the bulk solution from basin  202  to the gap between the substrate and the polishing article. The grooves  1142  may have various patterns, including a groove pattern of substantially circular concentric grooves on the polishing surface  1148  as shown in  FIG. 11 , an X-Y pattern as shown in  FIG. 12  and a triangular pattern as shown in  FIG. 13 . 
       FIG. 12  is a top plan view of another embodiment of a polishing pad having grooves  1242  disposed in an X-Y pattern on the polishing portion  1248  of a polishing pad  1240 . Perforations  1246  may be disposed at the intersections of the vertically and horizontally disposed grooves, and may also be disposed on a vertical groove, a horizontal groove, or disposed in the polishing article  1248  outside of the grooves  1242 . The perforations  1246  and grooves  1242  are disposed in the inner diameter  1244  of the polishing article and the outer diameter  1250  of the polishing pad  1240  may be free of perforations and grooves and perforations. 
       FIG. 13  is another embodiment of patterned polishing article  1340 . In this embodiment, grooves may be disposed in an X-Y pattern with diagonally disposed grooves  1345  intersecting the X-Y patterned grooves  1342 . The diagonal grooves  1345  may be disposed at an angle from any of the X-Y grooves  1342 , for example, between about 30° and about 60° from any of the X-Y grooves  1342 . Perforations  1346  may be disposed at the intersections of the X-Y grooves  1342 , the intersections of the X-Y grooves  1342  and diagonal grooves  1345 , along any of the grooves  1342  and  1345 , or disposed in the polishing article  1348  outside of the grooves  1342  and  1345 . The perforations  1346  and grooves  1342  are disposed in the inner diameter  1344  of the polishing article and the outer diameter  1350  of the polishing pad  1340  may be free of perforations and grooves. 
     Additional examples of groove patterns, such as spiraling grooves, serpentine grooves, and turbine grooves, are more fully described in co-pending U.S. Patent Provisional Application Ser. No. 60/328,434, filed on Oct. 11, 2001, entitled “Method And Apparatus For Polishing Substrates”, which is incorporated herein by reference to the extent not inconsistent with the claims and disclosure herein. 
     Conductive Polishing Surfaces 
       FIG. 14A  is a top sectional view of one embodiment of a conductive cloth or fabric  1400  that may be used to form a conductive polishing portion  1010  of the polishing article  1005 . The conductive cloth of fabric is composed of interwoven fibers  1410  coated with a conductive material as described herein. 
     In one embodiment, a weave or basket-weave pattern of the interwoven fibers  1410  in the vertical  1420  and horizontal  1430  directions is illustrated in  FIG. 14A . The invention contemplates other form of fabrics, such as yarns, or different interwoven, web, or mesh patterns to form the conductive cloth or fabric  1400 . In one aspect, the fibers  1410  are interwoven to provide passages  1440  in the fabric  1400 . The passages  1440  allow electrolyte or fluid flow, including ions and electrolyte components, through the fabric  1400 . The conductive fabric  1400  may be disposed in a polymeric binder, such as polyurethane. Conductive fillers may also be disposed in such a polymeric binder. 
       FIG. 14B  is a partial cross-sectional view of the conductive cloth or fabric  1400  disposed on the article support portion  1020  of the article  1005 . The conductive cloth or fabric  1400  may be disposed as one or more continuous layers over the article support portion  1020  including any perforations  1050  formed in the article support portion  1020 . The cloth or fabric  1400  may be secured to the article support portion  1020  by an adhesive. The fabric  1400  is adapted to allow electrolyte flow through the fibers, weaves, or passages formed in the cloth or fabric  1400  when immersed in an electrolyte solution. 
     Alternatively, the fabric  1400  may also be perforated to increase electrolyte flow therethrough if the passages  1440  are determined to not be sufficient to allow effective flow of electrolyte through the fabric  1400 , i.e., metal ions cannot diffuse through. The fabric  1400  is typically adapted or perorated to allow flow rates of electrolyte solutions of up to about 20 gallons per minute. 
       FIG. 14C  is a partial cross-sectional view of the cloth or fabric  1400  may be patterned with perforations  1450  to match the pattern of perforations  1050  in the article support portion  1020 . Alternatively, some or all of the perforations  1450  of the conductive cloth or fabric  1400  may not be aligned with the perforations  1050  of the article support portion  1020 . Aligning or non-aligning of perforations allow the operator or manufacturer to control the volume or flow rate of electrolyte through the polishing article to contact the substrate surface. 
     An example of the fabric  1400  is an interwoven basket weave of between about 8 and about 10 fibers wide with the fiber comprising a nylon fiber coated with gold. An example of the fiber is a nylon fiber, about 0.1 μm of cobalt, copper, or nickel material disposed on the nylon fiber, and about 2 μm of gold disposed on the cobalt, copper, or nickel material. 
     Alternatively, a conductive mesh may be used in place of the conductive cloth or fabric  1400 . The conductive mesh may comprises conductive fibers, conductive fillers, or at least a portion of a conductive cloth  1400  disposed in or coated with a conductive binder. The conductive binder may comprise a non-metallic conductive polymer or a composite of conductive material disposed in a polymeric compound. A mixture of a conductive filler, such as graphite powder, graphite flakes, graphite fibers, carbon fibers, carbon powder, carbon black, or fibers coated in a conductive material, and a polymeric material, such as polyurethane, may be used to form the conductive binder. The fibers coated with a conductive material as described herein may be used as a conductive filler for use in the conductive binders. For example, carbon fibers or gold-coated nylon fibers may be used to form a conductive binder. 
     The conductive binder may also include additives if needed to assist the dispersion of conductive fillers and/or fibers, improve adhesion between polymer and fillers and/or fibers, and improve adhesion between the conductive foil and the conductive binder, as well as to improve of mechanical, thermal and electrical properties of conductive binder. Examples of additives to improve adhesion include epoxies, silicones, urethanes, polyimides, or combinations thereof for improved adhesion. 
     The composition of the conductive fillers and/or fibers and polymeric material may be adapted to provide specific properties, such as conductivity, abrasion properties, durability factors. For example conductive binders comprising between about 2 wt. % and about 85 wt. % of conductive fillers may be used with the articles and processes described herein. Examples of materials that may be used as conductive fillers and conductive binders are more fully described in U.S. patent application Ser. No. 10/033,732, filed Dec. 27, 2001, which is incorporated herein by reference to the extent not inconsistent with the disclosure or claimed aspects herein. 
     The conductive binder may have a thickness of between about 1 microns and 10 millimeters, such as between about 10 microns and about 1 millimeter thick. Multiple layers of conductive binders may be applied to the conductive mesh. The conductive mesh may be used in the same manner as the conductive cloth or fabric  1400  as shown in  FIGS. 14B and 14C . The conductive binder may be applied in multiple layers over the conductive mesh. In one aspect, the conductive binder is applied to the conductive mesh after the mesh has been perforated to protect the portion of the mesh exposed from the perforation process. 
     Additionally, a conductive primer may be disposed on the conductive mesh before application of a conductive binder to improve adhesion of the conductive binder to the conductive mesh. The conductive primer may be made of similar material to the conductive binder fibers with a composition modified to produce properties having a greater intermaterial adhesion than the conductive binder. Suitable conductive primer materials may have resistivities below about 100 Ω-cm, such as between 0.001 Ω-cm and about 32 Ω-cm. 
     Alternatively, a conductive foil may be used in place of the conductive cloth or fabric  1400  as shown in  FIG. 14D . The conductive foil generally includes a metal foil  1480  disposed in or coated with a conductive binder  1490  on the support layer  1020 . Examples of material forming metal foils include metal coated fabrics, conductive metals such as copper, nickel, and cobalt, and noble metals, such as gold, platinum, palladium, iridium, rhenium, rhodium, rhenium, ruthenium, osmium, and combinations thereof, of which gold and platinum are preferred. The conductive foil may also include a nonmetallic conductive foil sheet, such as a copper sheet, carbon fiber woven sheet foil. The conductive foil may also include a metal coated cloth of a dielectric or conductive material, such as copper, nickel, or gold coating a cloth of nylon fibers. The conductive foil may also comprise a fabric of conductive or dielectric material coated with a conductive binder material as described herein. The conductive foil may also comprise a wire frame, screen or mesh of interconnecting conductive metal wires or strips, such as copper wire, which may be coated with a conductive binder material as described herein. The invention contemplates the use of other material in forming the metal foil described herein. 
     A conductive binder  1490  as described herein may encapsulate the metal foil  1480 , which allows the metal foil  1480  to be conductive metals that are observed to react with the surrounding electrolyte, such as copper. The conductive foil may be perforated with a plurality of perforation  1450  as described herein. While not shown, the conductive foil may be coupled to a conductive wire to power supply to bias the polishing surface. 
     The conductive binder  1490  may be as described for the conductive mesh or fabric  1400  and may be applied in multiple layers over the metal foil  1480 . In one aspect, the conductive binder  1490  is applied to the metal foil  1480  after the metal foil  1480  has been perforated to protect the portion of the metal foil  1480  exposed from the perforation process. 
     The conductive binder described herein may be disposed onto conductive fabric  1400 , foil  1480 , or mesh by casting liquid state adhesive or binder onto the fabric  1400 , foil  1480  or mesh. The binder is then solidified on the fabric, foil or mesh after drying and curing. Other suitable processing methods including injection mold, compression mold, lamination, autoclave, extrusion, or combinations thereof may be used to encapsulate the conductive fabric, mesh, or foil. Both thermoplastic and thermosetting binders may be used for this application. 
     Adhesion between the conductive binder and the metal foil components of the conductive foil may be enhanced by perforating the metal foil with a plurality of perforations having a diameter or width between about 0.1 μm and about 1 mm or by applying a conductive primer between the metal foil and the conductive binder. The conductive primer may be of the same material as the conductive primer for the mesh described herein. 
     Conductive Elements in Polishing Surfaces 
     In another aspect, the conductive fibers and fillers described herein may be used to form distinct conductive elements disposed in a polishing material to form the conductive polishing article  1005  of the invention. The polishing material may be a conventional polishing material or a conductive polishing material, for example, a conductive composite of conductive fillers or fibers disposed in the polymer as described herein. The surface of the conductive elements may form a plane with the surface of the polishing article or may extend above a plane of the surface of the polishing article. Conductive elements may extend up to about 5 millimeters above the surface of the polishing article. 
     While the following illustrate the use of conductive elements having a specific structure and arrangement in the polishing material, the invention contemplates that individual conductive fibers and fillers, and materials made therefrom, such as fabrics, may also be considered conductive elements. Further, while not shown, the following polishing article descriptions may include polishing articles having perforation and grooving patterns described herein and shown in  FIGS. 11-13 , with configurations to the patterns to incorporate the conductive elements described herein as follows. 
       FIGS. 15A-15B  depict a top and a cross-sectional schematic view of one embodiment of a polishing article  1500  having conductive elements disposed therein. The polishing article  1500  generally comprises a body  1510  having a polishing surface  1520  adapted to contact the substrate while processing. The body  1510  typically comprises a dielectric or polymeric material, such as a dielectric polymer material, for example, polyurethane. 
     The polishing surface  1520  has one or more openings, grooves, trenches, or depressions  1530  formed therein to at least partially receive conductive elements  1540 . The conductive elements  1540  may be generally disposed to have a contact surface  1550  co-planar or extending above a plane defined by the polishing surface  1520 . The contact surface  1550  is typically configured, such as by having a compliant, elastic, flexible, or pressure moldable surface, to maximize electrical contact of the conductive elements  1540  when contacting the substrate. During polishing, a contact pressure may be used to urge the contact surface  1550  into a position co-planar with the polishing surface  1520 . 
     The body  1510  is generally made permeable to the electrolyte by a plurality of perforations  1560  formed therein as described herein. The polishing article  1500  may have a perforation density between about 20% and about 80% of the surface area of the polishing article  1510  to provide sufficient electrolyte flow to facilitate uniform anodic dissolution from the substrate surface. 
     The body  1510  generally comprises a dielectric material such as the conventional polishing materials described herein. The depressions  1530  formed in the body  1510  are generally configured to retain the conductive elements  1540  during processing, and accordingly may vary in shape and orientation. In the embodiment depicted in  FIG. 15A , the depressions  1530  are grooves having a rectangular cross section disposed across the polishing article surface and forming an interconnecting “X” or cross pattern  1570  at the center of the polishing article  1500 . The invention contemplates additional cross sections, such as inverse trapezoidal and rounded curvature where the groove contacts the substrate surface as described herein. 
     Alternatively, the depressions  1530  (and conductive elements  1540  disposed therein) may be disposed at irregular intervals, be orientated radially, parallel, or perpendicular, and may additionally be linear, curved, concentric, involute curves, or other cross-sectional areas. 
       FIG. 15C  is a top schematic view of a series of individual conductive elements  1540  radially disposed in the body  1510 , each element  1540  separated physically or electrically by a spacer  1575 . The spacer  1575  may be a portion of dielectric polishing material or a dielectric interconnect for the elements, such as a plastic interconnect. Alternatively, the spacer  1575  may be a section of the polishing article devoid of either the polishing material or conductive elements  1540  to provide an absence of physical connection between the conductive elements  1540 . In such a separate element configuration, each conductive element  1540  may be individually connected to a power source by a conductive path  1590 , such as a wire. 
     Referring back to  FIGS. 15A and 15B , the conductive elements  1540  disposed in the body  1510  are generally provided to produce a bulk resistivity or a bulk surface resistivity of about 20 Ω-cm or less. In one aspect of the polishing article, the polishing article has a resistivity of about 2 Ω-cm or less. The conductive elements  1540  generally have mechanical properties that do not degrade under sustained electric fields and are resistant to degradation in acidic or basic electrolytes. The conductive elements  1540  are retained in the depressions  1530  by press fit, clamping, adhesive, or by other methods. 
     In one embodiment, the conductive elements  1540  are sufficiently compliant, elastic, or flexible to maintain electrical contact between the contact surface  1550  and the substrate during processing. Sufficient compliant, elastic, or flexible materials for the conductive element  1540  may have an analogous hardness of about 100 or less on the Shore D Hardness scale compared to the polishing material. A conductive element  1540  having an analogous hardness of about 80 or less on the Shore D Hardness scale for polymeric materials may be used. A compliant material, such as flexible or bendable fibers of material, may also be used as the conductive elements  1540 . 
     In the embodiment depicted in  FIGS. 15A and 15B , the conductive elements  1540  are embedded in the polishing surface  1510  disposed on an article support or sub-pad  1515 . Perforations  1560  are formed through both polishing surface  1510  and the article support  1515  around conductive elements  1540 . 
     An example of the conductive elements  1540  includes dielectric or conductive fibers coated with a conductive material or conductive fillers blended with a polymeric material, such as a polymer based adhesive, to make a conductive (and wear resistant) composite as described herein. The conductive elements  1540  may also comprise conductive polymeric material or other conductive materials as described herein to improve electrically properties. For example, the conductive elements comprise a composite of a conductive epoxy and a conductive fiber comprising a nylon fiber coated with gold, such as a nylon fiber coated with about 0.1 μm of cobalt, copper, or nickel disposed on the nylon fiber, and about 2 μm of gold disposed on the a nylon fiber, and carbon or graphite fillers to improve the composite&#39;s conductivity, which is deposited in a body of polyurethane. 
       FIG. 15D  is a cross-sectional schematic view of another embodiment of a polishing article  1500  having conductive elements disposed therein. The conductive elements  1500  may be generally disposed to have a contact surface co-planar or extending above a plane defined by the polishing surface  1520 . The conductive elements  1540  may include the conductive fabric  1400 , as described herein, disposed, encapsulated or wrapped around a conductive member  1545 . Alternatively individual conductive fibers and/or fillers may be disposed, encapsulated, or wrapped around the conductive member  1545 . The conductive member  1545  may comprise a metal, such as a noble metal described herein, or other conductive materials, such as copper, suitable for use in electropolishing processes. The conductive element  1540  may also comprise a composite of the fabric and a binder material as described herein with the fabric forming an outer contact portion of the conductive element  1560  and the binder typically forming an inner support structure. The conductive element  1560  may also comprise a hollow tube having a rectangular cross-sectional area with the walls of the tube formed of rigid conductive fabric  1400  and a bonding agent as described herein. 
     A connector  1590  is utilized to couple the conductive elements  1540  to a power source (not shown) to electrically bias the conductive elements  1540  during processing. The connector  1590  is generally a wire, tape or other conductor compatible with process fluids or having a covering or coating that protects the connector  1590  from the process fluids. The connector  1590  may be coupled to the conductive elements  1540  by molding, soldering, stacking, brazing, clamping, crimping, riveting, fastening, conductive adhesive or by other methods or devices. Examples of materials that may be utilized in the connector  1590  include insulated copper, graphite, titanium, platinum, gold, aluminum, stainless steel, and HASTELOY® conductive materials among other materials. 
     Coatings disposed around the connectors  1590  may include polymers such as fluorocarbons, poly-vinyl chloride (PVC) and polyimide. In the embodiment depicted in  FIG. 15A , one connector  1590  is coupled to each conductive element  1540  at the perimeter of the polishing article  1500 . Alternatively, the connectors  1590  may be disposed through the body  1510  of the polishing article  1500 . In yet another embodiment, the connector  1590  may be coupled to a conductive grid (not shown) disposed in the pockets and/or through the body  1510  that electrically couples the conductive elements  1540 . 
       FIG. 16A  depicts another embodiment of a polishing material  1600 . The polishing material  1600  includes a body  1602  having one or more at least partially conductive elements  1604  disposed on a polishing surface  1606 . The conductive elements  1604  generally comprise a plurality of fibers, strands, and/or flexible fingers that are compliant or elastic and adapted to contact a substrate surface while processing. The fibers are comprised of an at least partially conductive material, such as a fiber composed of a dielectric material coated with a conductive material as described herein. The fibers may also be solid or hollow in nature to decrease or increase the amount of compliance or flexibility of the fibers. 
     In the embodiment depicted in  FIG. 16A , the conductive elements  1604  are a plurality of conductive sub-elements  1613  coupled to a base  1609 . The conductive sub-elements  1613  include the at least partially electrically conductive fibers described herein. An example of the sub-elements  1613  include a nylon fiber coated with gold as described herein or carbon fiber. The base  1609  also comprises an electrically conductive material and is coupled to a connector  1690 . The base  1609  may also be coated by a layer of conductive material, such as copper, that dissolves from the polishing pad article during polishing, which is believed to extend the processing duration of the conductive fibers. 
     The conductive elements  1604  generally are disposed in a depression  1608  formed in the polishing surface  1606 . The conductive elements  1604  may be orientated between 0 and 90 degrees relative to the polishing surface  1606 . In embodiments where the conductive elements  1604  are orientated parallel to the polishing surface  1606 , the conductive elements  1604  may partially be disposed on the polishing surface  1606 . 
     The depressions  1608  have a lower mounting portion  1610  and an upper, clearance portion  1612 . The mounting portion  1610  is configured to receive the base  1609  of the conductive elements  1604 , and retain the conductive elements  1604  by press fit, clamping, adhesive, or by other methods. The clearance portion  1612  is disposed where the depression  1608  intersects the polishing surface  1606 . The clearance portion  1612  is generally larger in cross section than the mounting portion  1610  to allow the conductive elements  1604  to flex when contacting a substrate while polishing without being disposed between the substrate and the polishing surface  1606 . 
       FIG. 16B  depicts another embodiment of a polishing article  1600  having a conducting surface  1640  and a plurality of discrete conductive elements  1620  formed thereon. The conductive elements  1620  comprise fibers of dielectric material coated by a conductive material are vertically displaced from the conducting surface  1640  of the polishing article  1005  and are horizontally displaced from each other. The conducting elements  1620  of the polishing article  1600  are generally orientated between 0 to 90 degrees relative to a conducting surface  1640  and can be inclined in any polar orientation relative to a line normal to the conducting surface  1640 . The conductive elements  1620  may be formed across the length of the polishing pads, as shown in  FIG. 16B  or only may be disposed in selected areas of the polishing pad. The contact height of the conductive elements  1620  above the polishing surface may be up to about 5 millimeters. The diameter of the material comprising the conductive element  1620  is between about 1 mil (thousandths of an inch) and about 10 mils. The height above the polishing surface and a diameter of the conductive elements  1620  may vary upon the polishing process being performed. 
     The conductive elements  1620  are sufficiently compliant or elastic to deform under a contact pressure while maintaining an electrical contact with a substrate surface with reduced or minimal scratching of the substrate surface. In the embodiment shown in  FIGS. 16A and 16B , the substrate surface may only contacts the conductive elements  1620  of the polishing article  1005 . The conductive elements  1620  are positioned so as to provide an uniform current density over the surface of the polishing article  1005 . 
     The conductive elements  1620  are adhered to the conducting surface by a non-conductive, or dielectric, adhesive or binder. The non-conductive adhesive may provide a dielectric coating to the conducting surface  1640  to provide an electrochemical barrier between the conducting surface  1640  and any surrounding electrolyte. The conducting surface  1640  may be in the form of a round polishing pad or a linear web or belt of polishing article  1005 . A series of perforations (not shown) may be disposed in the conducting surface  1640  for provided flow of electrolyte therethrough. 
     While not shown, the conductive plate may be disposed on a support pad of conventional polishing material for positioning and handling of the polishing article  1600  on a rotating or linear polishing platen. 
       FIG. 17A  depicts a schematic perspective view of one embodiment of a polishing article  1700  comprised of conductive element  1704 . Each conductive element  1704  generally comprises a loop or ring  1706  having a first end  1708  and a second end  1710  disposed in a depression  1712  formed in the polishing surface  1724 . Each conductive element  1704  may be coupled to an adjoining conductive element to form a plurality of loops  1706  extending above the polishing surface  1724 . 
     In the embodiment depicted in  FIG. 17A , each loop  1706  is fabricated from a fiber coated by a conductive material and are coupled by a tie wire base  1714  adhered to the depression  1712 . An example of the loop  1706  is a nylon fiber coated with gold. 
     The contact height of the loop  1706  above the polishing surface may be between about 0.5 millimeter and about 2 millimeters and the diameter of the material comprising the loop may be between about 1 mil (thousandths of an inch) and about 50 mils. The tie wire base  1714  may be a conductive material, such as titanium, copper, platinum, or platinum coated copper. The tie wire base  1714  may also be coated by a layer of conductive material, such as copper, that dissolves from the polishing pad article during polishing. The use of a layer of conductive material on the tie wire base  1714  is believed to be a sacrificial layer that dissolves in preference of the underlying loop  1706  material or tie wire base  1714  material to extend the life of the conductive element  1704 . The conductive elements  1704  may be orientated between 0 to 90 degrees relative to a polishing surface  1724  and can be inclined in any polar orientation relative to a line normal to the polishing surface  1724 . The conductive elements  1704  are coupled to a power source by electrical connectors  1730 . 
       FIG. 17B  depicts a schematic perspective view of another embodiment of a polishing article  1700  comprised of conductive element  1704 . The conductive element  1704  comprises a singular coil  1705  of a wire composed of a fiber coated with a conductive material as described herein. The coil  1705  is coupled to a conductive member  1707  disposed on a base  1714 . The coil  1705  may be encircle the conductive member  1707 , encircle the base  1714 , or be adhered to the surface of the base  1714 . The conductive bar may comprise a conductive material, such as gold, and generally comprises a conductive material that is chemically inert, such as gold or platinum, with any electrolyte used in a polishing process. Alternatively, a layer  1709  of sacrificial material, such as copper, is disposed on the base  1714 . The layer  1709  of sacrificial material is generally a more chemically reactive material, such as copper, than the conductive member  1707  for preferential removal of the chemically reactive material compared to the material of the conductive member  1707  and the coil  1705 , during an electropolishing aspect, or anodic dissolution aspect, of the polishing process. The conductive member  1707  may be coupled to a power source by electrical connectors  1730 . 
     A biasing member may be disposed between the conductive elements and the body to provide a bias that urges the conductive elements away from the body and into contact with a substrate surface during polishing. An example of a biasing member  1718  is shown in  FIG. 17B . However, the invention contemplates that the conductive elements shown herein, for example in  FIGS. 15A-15D ,  16 A,  17 A- 17 D, may use a biasing member. The biasing member may be a resilient material or device including a compression spring, a flat spring, a coil spring, a foamed polymer such as foamed polyurethane (e.g., PORON® polymer), an elastomer, a bladder or other member or device capable of biasing the conductive element. The biasing member may also be a compliant or elastic material, such as compliant foam or aired soft tube, capable of biasing the conductive element against and improve contact with the substrate surface being polished. The conductive elements biased may form a plane with the surface of the polishing article or may extend above a plane of the surface of the polishing article. 
       FIG. 17C  shows a schematic perspective view of another embodiment of a polishing article  1700  having a plurality of conductive elements  1704 , disposed in a radial pattern from the center of the substrate to the edge. The plurality of conductive elements may be displaced from each other at intervals of 15°, 30°, 45°, 60°, and 90° degrees, or any other combinations desired. The conductive elements  1704  are generally spaced to provide as uniform application of current or power for polishing of the substrate. The conductive elements may be further spaced so as to not contact each other. Wedge portions  1704  of a dielectric polishing material of the body  1726  may be configured to electrically isolate the conductive elements  1704 . A spacer or recessed area  1760  is also formed in the polishing article to also isolate the conductive elements  1704  from each other. The conductive elements  1704  may be in the form of loops as shown in  FIG. 17A  or vertical extending fibers as shone in  FIG. 16B . 
       FIG. 17D  depicts a schematic perspective view of an alternative embodiment of the conductive element  1704  of  FIG. 17A . The conductive element  1704  comprises a mesh or fabric of interwoven conductive fibers  1706  as described herein having a first end  1708  and a second end  1710  disposed in a depression  1712  formed in the polishing surface  1724  to form one continuous conductive surface for contact with the substrate. The mesh or fabric may be of one or more layers of interwoven fibers. The mesh or fabric comprising the conductive element  1704  is illustrated as a single layer in  FIG. 17D . The conductive element  1704  may be coupled to a conductive base  1714  and may extend above the polishing surface  1724  as shown in  FIG. 17A . The conductive element  1704  may be coupled to a power source by electrical connectors  1730  connected to the conductive base  1714 . 
       FIG. 17E  shows a partial schematic perspective view of another embodiment of forming the conductive elements  1704  having loops  1706  formed therein and securing the conductive elements to the body  1726  of the polishing article. Passages  1750  are formed in the body  1724  of the polishing article intersecting grooves  1770  for the conductive elements  1704 . An insert  1755  is disposed in the passages  1750 . The insert  1755  comprises a conductive material, such as gold or the same material as the conductive element  1706 . Connectors  1730  may then be disposed in the passages  1750  and contacted with the insert  1755 . The connectors  1730  are coupled to a power source. Ends  1775  of the conductive element  1704  may be contacted with the insert  1755  for flow of power therethrough. The ends  1775  of the conductive element  1704  and the connectors  1730  are then secured to the conductive insert  1755  by dielectric inserts  1760 . The invention contemplated using the passages for every loop  1706  of the conductive element  1704 , at intervals along the length of the conductive element  1704 , or only at the extreme ends of the conductive element  1704 . 
       FIGS. 18A-C  are a series of schematic side views illustrating the elastic ability of the loops or rings of conductive materials described herein. A polishing article  1800  comprises a polishing surface  1810  disposed on a sub-pad  1820  formed over a pad support  1830  with grooves or depressions  1840  therein. A conductive element  1840  comprising a loop or ring  1850  of a dielectric material coated by a conductive material is disposed on a tie base  1855  in the depression  1870  and coupled with an electrical contact  1845 . A substrate  1860  is contacted with the polishing article  1800  and moved in relative motion with the surface of the polishing article  1800 . As the substrate contacts the conductive element  1840 , the loop  1850  compresses into the depression  1840  while maintaining electrical contact with the substrate  1860  as shown in  FIG. 18B . When the substrate is moved a sufficient distance to no longer contact the conductive element  1440 , the elastic loop  1850  returns to the uncompressed shape for additional processing as shown in  FIG. 18C . 
     Further examples of conductive polishing pads are described in United States Provisional patent application Ser. No. 10/033,732, filed Dec. 27, 2001, which is incorporated by reference to the extent not inconsistent with the aspects and claims herein. 
     Power Application 
     Power may be coupled into the polishing articles  1705  described above by using a connector as described herein or a power transference device. A power transference device is more fully detailed in United States Provisional patent application Ser. No. 10/033,732, filed Dec. 27, 2001, which is incorporated by reference to the extent not inconsistent with the aspects and claims herein. 
     Referring back to  FIGS. 18A-18C , power may be coupled to conductive elements  1840  by the use of electrical contacts  1845  comprising conductive plates or mounts disposed in the grooves or depressions  1870  formed in the polishing pad. In the embodiment shown in  FIG. 18A , the conductive elements  1840  are mounted on plates of a metal, such as gold, which are mounted on a support, such as disc, with the polishing article  1800 . Alternatively, the electrical contacts may be disposed on a polishing pad material between a conductive elements and a polishing pad material, for example, between the conductive element  1540  and the body  1510  as shown in  FIGS. 15A and 15B . The electrical contacts are then coupled to a power source by leads (not shown) as described above in  FIGS. 15A-15D . 
       FIGS. 19A-19D  are top and side schematic view of embodiments of a polishing article having extensions connected to a power source (not shown). The power source provides the current carrying capability, i.e., the anodic bias to a substrate surface for anodic dissolution in an ECMP process. The power source may be connected to the polishing article by one or more conductive contacts disposed around the conductive polishing portion and/or the article support portion of the polishing article. One or more power sources may be connected to the polishing article by the one or more contacts to allow for generating variable bias or current across portion of the substrate surface. Alternatively, one or more leads may be formed in the conductive polishing portion and/or the article support portion, which are coupled to a power source. 
       FIG. 19A  is a top plan view of one embodiment of a conductive polishing pad coupled to a power source by a conductive connector. The conductive polishing portion may have extensions, for example, a shoulder or individual plugs, formed in the conductive polishing portion  1910  with a greater width or diameter than the article support portion  1920 . The extensions are coupled to a power source by a connector  1925  to provide electrical current to the polishing article  1705 . In  FIG. 19B , extensions  1915  may be formed to extend parallel or laterally from the plane of the conductive polishing portion  1910  and extending beyond the diameter of the polishing support portion  1920 . The pattern of the perforation and grooving are as shown in  FIG. 13 . 
       FIG. 19B  is a cross-section schematic view of one embodiment of a connector  1925  coupled to a power source (not shown) via a conductive pathway  1932 , such as a wire. The connector comprises an electrical coupling  1934  connected to the conductive pathway  1932  and electrically coupled to the conductive polishing portion  1910  of the extension  1915  by a conductive fastener  1930 , such as a screw. A bolt  1938  may be coupled to the conductive fastener  1930  securing the conductive polishing portion  1910  therebetween. Spacers  1936 , such as washer, may be disposed between the conductive polishing portion  1910  and the fastener  1930  and bolt  1938 . The spacers  1936  may comprise a conductive material. The fastener  1930 , the electrical coupling  1934 , the spacers  1936 , and the bolt  1938  may be made of a conductive material, for example, gold, platinum, titanium, aluminum, or copper. If a material that may react with the electrolyte is used, such as copper, the material may be covered in a material that is inert to reactions with the electrolyte, such as platinum. While not shown, alternative embodiments of the conductive fastener may include a conductive clamp, conductive adhesive tape, or a conductive adhesive. 
       FIG. 19C  is a cross-section schematic view of one embodiment of a connector  1925  coupled to a power source (not shown) via a support  1960 , such as the upper surface of a platen or disc. The connector  1925  comprises a fastener  1940 , such as a screw or bolt having sufficient length to penetrate through the conductive polishing portion  1910  of the extension  1915  to couple with the support  1960 . A spacer  1942  may be disposed between the conductive polishing portion  1910  and the fastener  1940 . 
     The support is generally adapted to receive the fastener  1940 . An aperture  1246  may be formed in the surface of the support  1960  to receive the fastener as shown in  FIG. 19C . Alternatively, an electrical coupling may be disposed between the fastener  1940  and the conductive polishing portion  1910  with the fastener coupled with a support  1960 . The support  1960  may be connected to a power source by a conductive pathway  1932 , such as a wire, to a power source external to a polishing platen or chamber or a power source integrated into a polishing platen or chamber to provide electrical connection with the conductive polishing portion  1910 . The conductive path  1932  may be integral with the support  1960  or extend from the support  1960  as shown in  FIG. 19B . 
     In a further embodiment, the fastener  1940  may be an integrated extension of the support  1960  extending through the conductive polishing portion  1915  and secured by a bolt  1248  as shown in  FIG. 19D . 
       FIGS. 19E and 19F  show side schematic and exploded perspective views of another embodiment of providing power to a polishing article  1970  having a power coupling  1985  disposed between a polishing portion  1980  and a article support portion  1990 . The polishing portion  1980  may be made of a conductive polishing material as described herein or include a plurality of conductive elements  1975  as described herein. The conductive elements  1975  may be physically isolated from one another as shown in  FIG. 19F . The conductive elements  1975  formed in the polishing surface are adapted to electrically contact the power coupling  1985 , such as by a conductive base of the element. 
     The power coupling  1985  may comprise a wire interconnecting elements  1975 , multiple parallel wires interconnecting elements  1975 , multiple wires independently connecting elements  1975 , or a wire mesh interconnecting elements connecting elements  1975  to one or more power sources. Independent power sources coupled to independent wires and elements may have varied power applied while interconnected wires and elements may provide uniform power to the elements. The power coupling may cover a portion or all of the diameter or width of the polishing article. The power coupling  1985  in  FIG. 19F  is an example of a wire mesh interconnecting elements connecting elements  1975 . The power coupling  1985  may be connected to a power source by a conductive pathway  1987 , such as a wire, to a power source external to a polishing platen or chamber or a power source integrated into a polishing platen or chamber. 
     Thus, the invention provides a method and apparatus for local polishing and deposition control in a process cell. In one embodiment, the apparatus provides for selectively polishing discrete conductive portions of a substrate that advantageously minimizes dishing commonly associated with conventional processes. It is contemplated that the process cell may be adapted for metal deposition by reversing the bias potential while utilizing appropriate chemistries. 
     While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow.