Abstract:
The present invention provides an apparatus for electrochemical mechanical processing of a surface of a workpiece by utilizing a process solution. The apparatus of the present invention includes an electrode touching the process solution, a belt workpiece surface influencing device extended between a supply spool and a receiving spool. During the process, the surface of the workpiece is placed in proximity of the workpiece surface influencing device and the process solution is flowed through the process section and onto the surface while a potential difference is applied between the electrode and the surface of the workpiece.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. Prov. Appln. No. 60/350,214 filed Nov. 2, 2001 and is a continuation-in-part of U.S. Ser. No. 09/607,567 filed Jun. 29, 2000 (NT-001D1-US) which is a divisional of U.S. Ser. No. 09/201,929 filed Dec. 1, 1998 now U.S. Pat. No. 6,176,992 (NT-001-US), and U.S. Ser. No. 09/740,701 filed Dec. 18, 2000 (NT-020-US) claiming priority to U.S. Prov. No. 60/224,739 filed Aug. 10, 2000 (NT-020-P). 
     
    
     
       FIELD  
         [0002]    The present invention generally relates to semiconductor integrated circuit technology and, more particularly, to a device for electrotreating or electrochemically processing a workpiece.  
         BACKGROUND  
         [0003]    Conventional semiconductor devices such as integrated circuits (IC) generally comprise a semiconductor substrate, usually a silicon substrate, and a plurality of conductive material layers separated by insulating material layers. Conductive material layers, or interconnects, form the wiring network of the integrated circuit. Each level of conductor in the wiring network is isolated from the neighboring level of conductors by the insulating layers, also known as interlayer dielectrics. One dielectric material that is commonly used in silicon integrated circuits is silicon dioxide, although there is now a trend to replace at least some of the standard dense silicon dioxide material in IC structures with low-k dielectric materials such as organic, inorganic, spin-on and CVD candidates. Conventionally, IC interconnects are formed by filling a conductor such as copper in features or cavities etched into the dielectric interlayers by a metallization process. Copper is becoming the preferred conductor for interconnect applications because of its low electrical resistance and good electromigration property. The preferred method of copper metallization process is electroplating. In an integrated circuit, multiple levels of interconnect networks laterally extend with respect to the substrate surface. Interconnects formed in sequential layers can be electrically connected using features such as vias or contacts. In a typical interconnect fabrication process; first an insulating layer is formed on the semiconductor substrate, patterning and etching processes are then performed to form features or cavities such as trenches, vias, and pads etc., in the insulating layer. Then, copper is electroplated to fill all the features. In such electroplating processes, the wafer is placed on a wafer carrier and a cathodic (−) voltage with respect to an electrode is applied to the wafer surface while the electrolyte solution wets both the wafer surface and the electrode.  
           [0004]    Once the plating is over, a material removal step such as a chemical mechanical polishing (CMP) process step is conducted to remove the excess copper layer, which is also called copper overburden, from the top surfaces (also called the field region) of the workpiece leaving copper only in the features. An additional material removal step is then employed to remove the other conductive layers such as the barrier/glue layers that are on the field region. Fabrication in this manner results in copper deposits within features that are physically as well as electrically isolated from each other. Other conventional etching techniques can also be used, and conventional approaches exist that can remove both copper and the barrier/glue layers from the field region in one step. A particular type of CMP apparatus that works effectively is described in U.S. Pat. No. 6,103,628 entitled Reverse Linear Polisher with Loadable housing.  
           [0005]    The adverse effects of conventional material removal technologies may be minimized or overcome by employing a planar deposition approach that has the ability to provide thin layers of planar conductive material on the workpiece surface, as well as planar removal processes. These planar deposition and removal processes also have application in thru-resist processes employed in IC packaging. In these applications plating is performed into holes opened in resist layers onto seed films exposed on the bottom of each hole or opening.  
           [0006]    One technique is collectively referred to as Electrochemical Mechanical Processing (ECMPR), which term is used to include both Electrochemical Mechanical Deposition (ECMD) processes as well as Electro (ECME), and also called Electrochemical Mechanical Polishing. It should be noted that in general both ECMD and ECME processes are referred to as electrochemical mechanical processing (ECMPR) since both involve electrochemical processes and mechanical action.  
           [0007]    In one aspect of an ECMPR process, a workpiece surface influencing device (WSID) such as a mask, pad or a sweeper is used during at least a portion of the electrotreatment process when there is physical contact or close proximity and relative motion between the workpiece surface and the WSID. Descriptions of various planar deposition and planar etching methods and apparatus can be found in the following patents and pending applications, all commonly owned by the assignee of the present invention. U.S. Pat. No. 6,176,992 entitled, Method and Apparatus for Electrochemical Mechanical Deposition. U.S. application Ser. No. 09/740,701 entitled, Plating Method and Apparatus that Creates a Differential Between Additive Disposed on a Top Surface and a Cavity Surface of a Workpiece Using an External Influence, filed on Dec. 18, 2001, and U.S. application Ser. No. 09/961,193, filed on September 20, entitled, Plating Method and Apparatus for Controlling Deposition on Predetermined Portions of a Workpiece. These methods can deposit metals in and over cavity sections on a workpiece in a planar manner. They also have the capability of yielding novel structures with excess amount of metals over the features irrespective of their size, if desired.  
           [0008]    In ECMD methods, the surface of the workpiece is wetted by the electrolyte and is rendered cathodic with respect to an electrode, which is also wetted by the electrolyte. This typically results in conductive material deposition within the features of the workpiece, and a thin layer on the top surface of the workpiece. During ECMD, the wafer surface is pushed against or in close proximity to the surface of the WSID or vice versa when relative motion between the surface of the workpiece and the WSID results in sweeping of the workpiece surface. Planar deposition is achieved due to this sweeping action as described in the above-cited patent applications.  
           [0009]    In ECME methods, the surface of the workpiece is wetted by the electrolyte or etching solution, but the polarity of the applied voltage is reversed, thus rendering the workpiece surface more anodic compared to the electrode. If no voltage difference is applied, the etching is chemical etching and can be performed when there is physical contact or close proximity between the workpiece and the WSID. The chemical etching can be carried out using the process solution or an etching solution.  
           [0010]    Very thin planar deposits can be obtained by first depositing a planar layer using an ECMD technique and then using an ECME technique on the planar film in the same electrolyte by reversing the applied voltage. Alternately the ECME step can be, carried out in a separate machine and a different etching electrolyte. The thickness of the deposit may be reduced in a planar manner. In fact, an ECME technique may be continued until all the metal on the field regions is removed. It should be noted that a WSID may or may not be used during the electroetching or etching process since substantially planar etching can be achieved with or without the use of WSID.  
           [0011]    [0011]FIG. 1A, is a schematic illustration of an exemplary conventional ECMPR system  100  used for processing wafers. In FIG. 1A, a WSID  102  having openings  104  in it, is disposed in close proximity of a workpiece or wafer  106  to be processed. The WSID  102  is supported by a support plate  108  having perforations  110  or openings in it. The wafer  106  is a silicon wafer to be plated with a conductive material, preferably copper or a copper alloy. The wafer  106  is retained by a wafer carrier  111  so as to position front surface  112  of the wafer against top surface  113  of the WSID  102 . The openings  104  are designed to assure uniform deposition of copper from an electrolyte solution, depicted by arrows  114 , onto the front surface  112 , or uniform electroetching from the front surface  112 . The perforations  110  may or may not exactly match the design of the openings  104 . Generally, the openings  104  are designed for uniform deposition, and perforations  110  are such that the electrical field and electrolyte solution pass substantially unhindered to the WSID  102 . Therefore, the area of perforations per unit area of the support plate  108  is equal to or larger than the area of the openings per unit area of the WSID  102 . The top surface  113  of the WSID  102  facing the front surface  112  of the wafer is used as the sweeper and the WSID  102  itself establishes appropriate electrolyte flow and electric field flow to the front surface  112  for globally uniform deposition or etching. Such an ECMPR system  100  also includes an electrode  116 , which is immersed in the electrolyte solution  114 . The electrolyte  114  is in fluid communication with the electrode  116  and the front surface  112  of the wafer  106  through the openings  104  in the WSID  102 .  
           [0012]    The electrode  116  is typically a Cu piece for Cu deposition. It may also be an inert electrode made of, for example, Pt coated Ti. An exemplary copper electrolyte solution may be copper sulfate solution with additives such as accelerators, suppressors, leveler, chloride and such, which are commonly used in the industry. In planar deposition techniques such as ECMD, the leveler is not very necessary since leveling is automatically done by the process. Leveler may be added however, for optimization of other process results such as gap fill etc. The top surface  113  of the WSID  102  sweeps the front surface  112  of the wafer while an electrical potential is established between the electrode  116  and the front surface  112  of the wafer. For deposition of a planar film such as copper, the front surface of the wafer  102  is made more cathodic (negative) compared to the electrode  116 , which becomes the anode. For electroetching in the same ECMPR system the wafer surface is made more anodic than the electrode. For chemical etching, chemical etching or etching, no potential difference is applied between the wafer and the electrode.  
           [0013]    As shown in FIG. 1B, the structure of the WSID  102  may have a top layer  120 , an intermediate layer  122 , and a bottom layer  124 . The top layer  120  may preferably be made of an abrasive material such as a the class of fixed-abrasive-films supplied by the 3M company, or any of the other so-called pad materials used in CMP applications, such as the polymeric IC-1000 material supplied by Rodel. The thickness of the top layer  120  may be typically in the range of 0.05-2 mm. The intermediate layer  122  is the mounting layer for the top layer  120  and the holes are defined in the intermediate layer  122  and the bottom layer  124 . The intermediate layer  122  is typically made of a hard plastic material such as polycarbonate with a thickness range of 1-3 mm. The bottom layer  124  functions as a compression layer for the whole structure. The bottom layer is made of a polymeric foam material such as polyurethane or polypropylene. U.S. Pat. No. 6,413,403 and 6,413,388, which are assigned to the assignee of the present invention, disclose various examples of WSIDs. Further, U.S. Application with Ser. No. 09/960,236 filed on Sep. 20, 2001, entitled Mask Plate Design, discloses various WSID embodiments. Further, U.S. Application with Ser. No. 10/155,828 filed on May 23, 2002, entitled Low Force Electrochemical Mechanical Deposition Method and Apparatus, discloses a WSID structure having a flexible and abrasive top layer attached on a highly compressible layer. Both applications are assigned to the assignee of the present invention. The WSID is placed on a porous support plate which may be or may not be an integral part of the WSID. In this particular structure, electrolyte is flowed through the openings or the open pores of the compressible layer and the openings in the flexible layer.  
           [0014]    To this end, however, while these techniques assist in obtaining planar metal deposits or novel metal structures on workpieces and wafers, there is still a need for further development of high-throughput approaches and devices that can yield deposits with better uniformity and high yield.  
         SUMMARY  
         [0015]    The present invention provides an apparatus for electrochemical mechanical processing of a surface of a workpiece by utilizing a process solution. The apparatus of the present invention includes an electrode touching the process solution, a belt workpiece surface influencing device extended between and attached to a supply structure and a receiving structure. Further, a process section of the workpiece surface influencing device is disposed in proximity to the surface of the workpiece. The process solution is capable of flowing through the process section and onto the surface of the workpiece. A potential difference is capable of being maintained between the electrode and the surface of the workpiece during the process. A mechanism moves the process section of the workpiece surface influencing device while the solution flows through the workpiece surface influencing device.  
           [0016]    Further, the present invention provides a method for electrochemical mechanical processing a surface of a workpiece. The method includes the steps of providing a workpiece surface influencing device having channel pattern. The workpiece surface influencing device is extended between and attached to a supply spool and a receiving spool. The workpiece is placed in close proximity of a first process section of the workpiece surface influencing device. A process solution is flowed through the channels of the first process section of the workpiece surface influencing device and onto the workpiece surface. The surface is electrochemical mechanical processed while establishing relative motion between the first process section of the workpiece surface influencing device and the surface of the workpiece during the electrochemical mechanical processing. During the process, a potential difference is maintained between the electrode and the workpiece.  
           [0017]    It is an object of the present invention to provide a belt WSID design that assists in providing metal layers with better uniformity.  
           [0018]    It is a further object of the present invention to provide a belt WSID design that have openings or channels grouped in a multiplicity of sections of the belt WSID.  
           [0019]    The present invention achieves, either singularly or in combination, these and other objects of the invention using a belt WSID in an electrochemical mechanical processing apparatus. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1A is schematic illustration of a conventional ECMPR system;  
         [0021]    [0021]FIG. 1B is a schematic illustration of a workpiece surface influencing device;  
         [0022]    [0022]FIG. 2A is a schematic illustration of surface region of a substrate surface having features formed therein;  
         [0023]    [0023]FIG. 2B is a schematic illustration of the substrate shown in FIG. 2A, wherein copper has been deposited on the substrate surface;  
         [0024]    [0024]FIG. 3 is a schematic illustration of an ECMPR system employing a belt workpiece surface influencing device;  
         [0025]    [0025]FIG. 4A is a schematic view of a process section of the belt workpiece surface influencing device;  
         [0026]    [0026]FIG. 4B is a schematic view of a surface of a process section of another belt workpiece surface influencing device;  
         [0027]    [0027]FIG. 5 is a schematic illustration of a workpiece surface influencing device with process sections having the same channel patterns, wherein the process sections are not spaced apart;  
         [0028]    [0028]FIG. 6 is a schematic illustration of a workpiece surface influencing device with process sections having the same channel patterns, wherein the process sections are spaced apart;  
         [0029]    [0029]FIG. 7 is a schematic illustration of a workpiece surface influencing device with process sections having different channel patterns;  
         [0030]    [0030]FIG. 8 is a schematic illustration of electrical contact locations in the ECMPR system shown in FIG. 3;  
         [0031]    [0031]FIG. 9 is a schematic illustration of a conditioning device of the belt workpiece surface influencing device of the present invention;  
         [0032]    FIGS.  10 A- 12  are schematic illustrations of the belt workpiece surface influencing device systems;  
         [0033]    FIGS.  13 A- 13 C are schematic illustrations of alternative belt support means; and  
         [0034]    FIGS.  14 A- 14 B is a schematic illustrations of a multiple workpiece surface influencing device system. 
     
    
     DETAILED DESCRIPTION  
       [0035]    The preferred embodiments will now be described using the example of fabricating interconnects for integrated circuit applications. It should, however, be recognized that present invention can be used to operate on any workpiece with various electroplated materials such as Au, Ag, Ni, Pt, Pd, Fe, Sn, Cr, Pb, Zn, Co and their alloys with each other or other materials, for many different applications such as packaging, flat panel displays, magnetic heads and such. In the examples provided below, the example material that is electroplated will be described as copper, but it will be understood that other materials can instead be used.  
         [0036]    Further, the preferred embodiment will be described in the context of depositing planar layers. Other novel structures, which may also require electroetching, chemical etching and other processes, as described in the above-mentioned ECMPR patents and applications, can also be obtained using this invention. In one embodiment, for example, a planar conductive layer is formed on a wafer surface by an ECMD process using a belt WSID structure of the present invention. Other structures may also be formed using low-force electrochemical mechanical etching (ECME) as disclosed in previous applications.  
         [0037]    Details of the surface region of an exemplary substrate  200  to process with the present invention are shown in FIGS.  2 A- 2 B. The substrate  200  comprises a patterned layer  202 , preferably an insulating layer formed on a workpiece  204 . The insulating layer may be comprised of an insulation material such as silicon oxide and formed using well-known patterning and etching techniques pursuant to metal interconnect design rules. In this embodiment, the insulating layer  202  may be comprised of cavities or gaps, namely the first cavity  206  and a second cavity  208  separated from one another by field region  210 . In this embodiment, the cavities can be formed such that the first cavity  206  may be a via, the second cavity  208  may be a trench including a second via  209  at the bottom. Top surfaces  210  are also called field regions. One or more thin layers of barrier or glue layer  217  having materials, for example, Ta, TaN, Ti, TiN, or WN coats the cavities as well as the top surfaces. A thin film  218  of copper is coated as the seed layer on top of the barrier layer for the subsequent electroplated copper layer. The copper seed layer provides a base layer on which nucleation and growth of the subsequent deposition layer can be promoted. Referring to FIG. 2B, with the present invention, a planar copper layer  220  can be deposited into the cavities  206 ,  208 ,  209  and on the field region  210 . The deposition process as well as other processes which are performed using the present invention described below.  
         [0038]    [0038]FIG. 3 shows an embodiment of an ECMPR system  300  comprising a belt WSID assembly  301  of the present invention and a carrier head  302 . The belt WSID assembly  301  comprises a WSID belt  303  having an upper surface  304  or a process surface and a back surface  306  and a set of rollers  308 . The WSID belt may be made of a flexible material and may preferably have an abrasive process surface for sweeping action. The belt WSID may have a plurality of openings  314  or channels allowing a process solution such as a plating electrolyte or the electroetching solution, depicted by arrows  316 , to flow between an electrode  317  and a front surface  318  of a workpiece  320  or a wafer. For clarification purposes, the container or the cavity holding the process solution is not shown in the Figures. The front surface  318  of the wafer may comprise the exemplary substrate shown in FIGS.  2 A- 2 B. As will be described below, the process surface of the belt  303  may also include raised surfaces to perform sweeping action (see FIG. 4B). The belt WSID  303  is moved on the rollers  308  for either in unidirectional or bi-directional linear manner by a moving mechanism (not shown). The belt WSID may be moved during electroetching or electrodeposition process in close proximity of the front surface of the wafer. The belt WSID may be moved on the front surface of the wafer to sweep the front surface during the electroetching or electroplating. The moving mechanism also appropriately tensions the belt WSID  303  to assure contact with the workpiece surface during ECMPR. The back surface  306  of the belt WSID  303  is placed on a top surface  307  of a plate  309 . The plate  309  may be comprised of one or more layers. In this embodiment the plate  309  is comprised of an upper layer  322  and a lower layer  324 . The upper layer  322  may be made of a compressible material. The bottom layer  324  is a support layer and made of a rigid material so that it can support the compressible layer. Openings  310 A in the compressible layer and the openings  310 B in the rigid layer allow process solution to flow through the plate  303 . Further, the compressible layer  322  may have the openings  310  or may be made of a porous material that allows process solution to flow though its open pores. The belt WSID is tensioned on top surface of the plate so that the top surface  307  of the plate  309  fully contact with a bottom surface portion of the belt WSID that covers the top surface  307 . If needed, as the belt WSID moved on the upper layer, the bottom surface of the belt WSID slides on the upper surface of the plate while the process solution  316  flows through both the plate and the belt WSID  303 .  
         [0039]    The belt WSID may be made of a polymeric film such as a fixed abrasive film commonly used in CMP processes and available from 3M Company. The flexible material of the belt WSID is thin and having a thickness in the range of 0.2-2 mm. The belt WSID may also have a composite structure having multiplicity of thin layers. The belt WSID may have relatively flat, surface such as the lapping films containing 0.05-0.5 micron size abrasive particles (available from e.g. Buehler or 3M companies), or small diameter posts with flat tops or pyramidal posts such as those employed in fixed abrasive pads provided by 3M company. The surface of the belt WSID is preferably abrasive to efficiently sweep the surface of the workpiece.  
         [0040]    The upper layer of the plate is made of a foam or gel material, which is easily compressible under an applied force but recovers back to its original shape once the force is removed. The upper layer of the plate may have thickness in the range of 1-5 mm. Examples of such materials can be polyurethane, polypropylene, rubber, EVA, their mixtures and the like. The lower layer of the plate is a porous plate or it has many openings to let electrolyte and electric field freely flow towards the substrate surface. The lower layer  100   c  may itself be the electrode.  
         [0041]    During the process, the wafer  320  is held by the carrier head in close proximity of the belt WSID such that the process solution flowing through the plate  309  and the belt WSID  303  wets the front surface of the wafer. As shown in exploded view in FIG. 4A, the wafer  320  processed over a predetermined area  321  or a process area of the process surface of the belt WSID  303 . As the belt is tensioned over the upper surface  307  of the plate, the compressible layer pushes the belt upward. Additionally, if the wafer  320  is contacted with the process surface, the compressible layer pushes the wafer against the front surface of the wafer. The process area  321  is renewed by advancing the belt WSID such that a used process area is replaced by a fresh process area by rolling the used process area over the storage spool  312  and thereby drawing fresh process area from the supply spool  311 . Advancement of the belt can be carried out after processing about 20-100 wafers or before the extensive use of the same area of WSID starts impacting the process results in a negative manner. Owing to this feature, the belt WSID  303  reduces manufacturing down time and increases system throughput. Alternately, it is possible to index or gradually advance the WSID by a small amount, such as in the range of 1-5 mm, for each wafer processed. During the process, the wafer carrier  304  can move the wafer on or above the belt WSID  303  laterally and rotate about the rotation axis z of the wafer carrier. As mentioned above, the belt WSID of the present invention can also be moved laterally while the wafer is moved on it by the carrier head. In another embodiment belt may be a loop shape or continuous belt which is rotated by rollers that replace storage and supply spools. Belt is placed around the rollers and tensioned. The rollers in this embodiment are rotated by a drive system and the rotational motion of the rollers cause belt to be moved linearly with respect to the wafer surface that is being processed.  
         [0042]    As also shown in FIG. 4A, width of the belt WSID is preferably shorter than the diameter of the wafer to be processed. As will be described below, this feature of the belt allows electrical contact to be established between the front surface of the wafer and a power source (not shown). For chemical etching processes, width of the WSID may be equal to or larger than the diameter of the wafer, since there is no need to make electrical contact. The belt WSID may be a single layer or a composite layer made up more than one layer. If the belt includes more than one layer, those layers may or may not be the same size. However, the total thickness of such composite layer is typically 0.5-2 mm. As can be seen in FIG. 4B in perspective view, a WSID  500  may have a raised surface  502  which is smaller in comparison to the top surface  504  of the WSID  500 . In this embodiment the sweeping function is performed by the raised surface  502 . It is preferred that the raised surface  502  contains an abrasive layer.  
         [0043]    The exemplary ECMPR system  300  of FIG. 3 is capable of performing planar or non-planar plating as well as planar or non-planar electroetching. In this respect, if non-planar process approach is chosen, the front surface of the wafer is brought into proximity of the process surface of the belt WSID  303 , but it does not touch it, so that non-planar metal deposition can be performed. Further, if planar process approach is chosen, the front surface of the wafer contacts the process surface as a relative motion is established between the belt WSID and the front surface of the wafer. As the process solution is delivered through the openings in the belt, either the belt is laterally moved or the wafer is rotated and laterally moved, or both the belt WSID and the wafer are moved, while the front surface contacts the process surface. Under an applied potential between the wafer and the electrode, and in the presence of the process solution that rises through the belt WSID  303 , the metal such as copper, is plated on or etched off the front surface of the wafer depending on the polarity of the voltage applied between the wafer surface and the electrode.  
         [0044]    FIGS.  5  to  7  show various belt WSID process area designs. In accordance of the principles of the present invention, the belt WSID may have various grouped opening or channel patterns which are generally adapted either as a continuous pattern along the belt WSID or more than one pattern repeating along the belt WSID. As shown in FIG. 5, in one embodiment, a WSID belt  330  may have channels  332  which are formed in a continuous pattern extending along the belt WSID  330 . In this particular design, channels  332  are shaped as parallel slits, although they may be shaped as holes or other openings in various geometrical shapes, or various radial designs. In this embodiment, depending on the process requirements and the wafer size, a plurality of process areas  334  can be extended end to end fashion. The belt WSID  330  can be moved laterally on the plate for the mechanical sweeping action. After certain number of wafer processing on the same processing area, the belt WSID is advanced to get fresh process area. Alternately the belt can be moved incrementally in a specific direction during processing. This way an incremental fresh belt WSID portion is moved into the process area in a continuous manner.  
         [0045]    As shown in another embodiment in FIG. 6, a belt WSID  336  may have channels  338  that are grouped in process areas  338  that are separated from one another. After each use the process areas are advanced to replace them with the new ones. With such belt, the lateral motion is mainly provided by the wafer holder during the process.  
         [0046]    Although the belt WSID may have a single channel pattern extending along the belt WSID, such as those shown in FIGS. 5 and 6, the belt WSID may also comprise a multiplicity of opening or channel patterns. As exemplified in FIG. 7, a belt WSID  340  may have a number of process areas  342 A- 342 D that comprise channels  344 , having different sizes and shapes, as well as raised surfaces on the process areas for the sweeping action. For example, the process area  342 A comprises channels  344  shaped as round holes while the process area  342 B comprises channels  344  shaped as slits. The process area  342 C comprises channels  344  having a radial pattern, and the process area  342 D comprises channels  344  formed as rectangular holes. Channels  344  in each process area  342 A- 342 D may also differ in size and shape as well as in how they are distributed on that particular process area. Each process area may be repeatedly used for ECMD or ECME or chemical etching process purposes by advancing or recoiling the belt WSID for the particular process area. By giving a specific shape and distribution to the channels, the copper layer profile can be controlled. By employing a specific process area, the thickness profile of the copper layer can be made uniform or can be varied into a desired profile. For example, in an exemplary operation sequence, the wafer may be first ECMD processed on the process area  342 A to deposit a planar copper layer. Subsequently, the same wafer may be ECME processed or chemically mechanically etched to etch back the planar copper layer on the process area  342 B. In this example, the process area  342 A may have a channel pattern that is suitable for ECMD process giving uniform deposition, and the process area  342 B may have a pattern that is suitable for ECME or CME or chemical etching processes, yielding uniform material etching or removal.  
         [0047]    During the ECMPR an electrical potential is established between the front surface of the wafer and the electrode  317 . As shown in FIG. 8 in a side view of the system  300 , the front surface of the wafer  320  is connected to a power source (not shown) through contacts  350  touching and sliding on a peripheral region  352  of the front surface  318  of the wafer. Examples of such contacts are described in U.S. application Ser. No. 09/760,757 entitled Method and Apparatus for Electrodeposition of Uniform Film with Minimal Edge Exclusion on Substrate, filed on Jan. 17, 2001 and U.S. Provisional Application No. 60/348,758, entitled “Method and System for Providing Electrical Contacts for Electrotreating Processes filed on Oct. 26, 2001, both are commonly owned by the assignee of the present invention.  
         [0048]    During the process step that involves the WSID being in close proximity to, and typically in contact with, the front surface of the wafer, small particles of the metal on the front surface or the non-conductive particles from the sources may attach onto the WSID material. These particles may exist because of the fact that they may be just physically removed from the substrate surface or they may originate from the plating solution due to poor filtration of the plating solution. Such particles can be cleaned using the conditioning apparatus of the present invention. As shown in FIG. 9, the carrier head  302  may include a conditioning apparatus  360  with brushes  362 . As illustrated, the brushes  362  are disposed around the periphery of the carrier head  302 . The brushes  362  provide for conditioning of the WSID  303  by dislodging particles by mechanically sweeping them out. In this embodiment, the ECMPR process on the workpiece  320 , whether ECMD or ECME, and conditioning of the WSID  303  can occur at the same time, during the same process. In this particular situation, in order to condition the entire WSID  303 , the lateral movement of the carrier head  302  or the WSID  303  should preferably be equal or greater than the radius of the carrier head  302  so that the WSID portion that the carrier head covers can effectively be cleaned. Alternately the conditioning brushes are not attached to the head but they are placed, using suitable means, out of end of an area that is scanned by the lateral movement of the head. The belt may then be moved to assure that the entire length of the processing area is brushed by the conditioning brushes.  
         [0049]    FIGS.  10 A- 12  shows various embodiments of the belt WSID. FIG. 10A shows a belt WSID  400  in an ECMPR system  402 . As shown in detail in FIG. 10B, the belt WSID  400  is comprised of a bi-layer with a top layer  404  and a bottom layer  406  attached to the top layer. The top layer  404  may be an abrasive layer or a layer containing abrasives. The bottom layer  406  is a thin compressible layer. Channels  408  are formed through the belt  400  to allow a process solution  407  to flow through between an electrode  408  and a front surface  410  of a wafer  412 . Referring to FIG. 10A, in use, the compressible layer of the belt  402  is placed on a plate  414  of the system  402 . The plate in this embodiment preferably made of a rigid material. The plate comprises channels  416  to allow process solution to flow through the plate. During the process the compressible layer of the belt, which is supported by the rigid plate of the system, pushes the belt towards the wafer. In this embodiment, apart from the previous embodiment, the compressible layer is an integral part of the belt WSID. The surface interface between the compressible layer and the plate  414  is preferably a low friction interface in this example and the previous examples. For the belt described above embodiment, the top layer is typically 0.2-2 mm thick and the bottom layer is typically 1-5 mm thick, which layers are glued together, with the channels dimensioned to allow fluid flow therethrough.  
         [0050]    [0050]FIG. 11A shows a belt WSID  420  in an ECMPR system  422 . As shown in detail in FIG. 11B, the belt WSID  420  is comprised of a single layer which may be an abrasive layer or a layer containing abrasives. Channels  424  are formed through the belt  420  to allow a process solution  426  to flow through between an electrode  428  and a front surface  430  of a wafer  432 . Referring to FIG. 11A, in use, the belt  302  is placed on a roller system  434  having a plurality of rollers  436  placed on a frame  438 . The frame is immersed in the process solution and allow the passage of the process solution through the roller system. Rollers are placed side by side along the width of the belt and they are able to move up and down when the wafer contacts the belt during the process. During the process roller system pushes the belt against the wafer and acts like a compressible layer shown in the previous embodiments. Roller surfaces may preferably contain a compressible material to establish contact between the wafer surface and the belt surface.  
         [0051]    [0051]FIG. 12 shows a belt WSID  440  in a ECMPR system  442 . The belt WSID  440  is comprised of a single layer that may be an abrasive layer or a layer containing abrasives. Channels  444  are formed through the belt  440  to allow a process solution  446  to flow through between an electrode  428  and a front surface  430  of a wafer  432 . The process solution is held in a container (not shown). The belt is supported on top ends  450  of side walls the container during the process. In addition to that, the flow pressure of the process solution process pushes the belt against the wafer while providing additional support. Pressure of the solution acts like a compressible layer shown in the previous embodiments  
         [0052]    FIGS.  13 A- 13 C illustrate various additional mechanisms to support the belt  440  that is shown in the embodiment described with help of FIG. 12. As shown in FIG. 13A, the belt WSID  440  may also be supported by a plurality of hollow spheres  452  located under the belt  440  and floating on the process solution  446  while confined by the wall tops  450  of the process container. The spheres may be filled with a gas such as air or a lighter gas. In addition to the pressure of the solution, spheres  452  adds an additional compressible support to the belt.  
         [0053]    In FIG. 13B, the same can be achieved using a floatable layer  454 , placed under the belt  440 , having channels  456  to allow process solution  446  to flow through it. The floatable layer  454  may be made of a sponge like material such polyurethane. The floatable layer may also have air pockets (not shown) in it. Further, as illustrated in FIG. 13C, both the floatable layer  454  and the spheres  452  are placed under the belt  440  for the same purpose.  
         [0054]    [0054]FIGS. 14A and 14B show a multiple WSID system  600  comprising a first belt WSID  602  and a second belt WSID  604  which is located adjacent the first belt WSID. The system  600  may have more than two WSID belts if needed. The system  600  allows a wafer  606  to be processed on both belts  602  and  604  during the process. The belts  602 ,  604  may have the repeating channel patterns shown in FIGS. 5 and 6. The belts may also have different channel patterns designed for different thickness distributions. For example, a first step of the process can be done using ECMD on the first belt  602  in a way that yields edge thick deposit profile. Then, the belt  604  can be used for an ECME step to reduce the overall thickness of the deposit. The pattern of the belt  604  may be such that more material can be etched from the edge portions to yield uniform thickness profile. If needed process may be continued on the first belt and vice versa.  
         [0055]    Although various preferred embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications of the exemplary embodiment are possible without materially departing from the novel teachings and advantages of this invention.