Abstract:
An apparatus for processing a material on a wafer surface includes a cavity defined by a peripheral wall and configured to direct a process solution and direct it to the surface to to a first wafer surface region without being directed to a second wafer surface region, a head configured to hold the wafer so that the surface of the wafer faces the cavity, and an electrical contact member positioned outside the cavity peripheral wall and configured to contact the second wafer surface region extending beyond the cavity, when the wafer is moved relative to the contact member. Advantages of the invention include substantially full surface treatment of the wafer.

Description:
This application is a continuation of U.S. Ser. No. 09/760,757, filed Jan. 17, 2001, now U.S. Pat. No. 6,610,190, which claims priority to prior U.S. provisional application Ser. No. 60/245,211, filed Nov. 3, 2000, the entire disclosure of which is expressly incorporated by reference herein. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to electrodeposition process technology and, more particularly, to an electrodeposition process that yields uniform and planar deposits. 
   2. Description of Related Art 
   Conventional semiconductor devices generally include a semiconductor substrate, usually a silicon substrate, and a plurality of sequentially formed dielectric interlayers such as silicon dioxide and conductive paths or interconnects made of conductive materials. The interconnects are usually formed by filling a conductive material in trenches etched into the dielectric interlayers. In an integrated circuit, multiple levels of interconnect networks laterally extend with respect to the substrate surface. The interconnects formed in different layers can be electrically connected using vias or contacts. A conductive material filling process of such features, i.e., via openings, trenches, pads or contacts, can be carried out by depositing a conductive material over the substrate including such features. Excess conductive material on the substrate can then be removed using a planarization and polishing technique such as chemical mechanical polishing (CMP). 
   Copper (Cu) and Cu alloys have recently received considerable attention as interconnect materials because of their superior electromigration and low resistivity characteristics. The preferred method of Cu deposition is electrodeposition. During fabrication, copper is electroplated or electrodeposited on substrates that are previously coated with barrier and seed layers. Typical barrier materials generally include tungsten (W), tantalum (Ta), titanium (Ti), their alloys and their nitrides. A typical seed layer material for copper is usually a thin layer of copper that is CVD or PVD deposited on the aforementioned barrier layer. 
   There are many different designs of Cu plating systems. For example, U.S. Pat. No. 5,516,412 issued on May 14, 1996, to Andricacos et al. discloses a vertical paddle plating cell that is configured to electrodeposit a film on a flat article. U.S. Pat. No. 5,985,123 issued on Nov. 16, 1999, to Koon discloses yet another vertical electroplating apparatus, which purports to overcome the non-uniform deposition problems associated with varying substrate sizes. 
   During the Cu electrodeposition process, specially formulated plating solutions or electrolytes are used. These solutions or electrolytes contain ionic species of Cu and additives to control the texture, morphology, and the plating behavior of the deposited material. Additives are needed to make the deposited layers smooth and somewhat shiny. 
   There are many types of Cu plating solution formulations, some of which are commercially available. One such formulation includes Cu-sulfate (CuSO 4 ) as the copper source (see James Kelly et al., Journal of The Electrochemical Society, Vol. 146, pages 2540-2545, (1999)) and includes water, sulfuric acid (H 2 SO 4 ), and a small amount of chloride ions. As is well known, other chemicals, which are often referred to as additives, can be added to Cu plating solutions to achieve desired properties of the deposited material (e.g., see Robert Mikkola and Linlin Chen, “Investigation of the Roles of the Additive Components for Second Generation Copper Electroplating Chemistries used for Advanced Interconnect Metallization”, Proceedings of the International Interconnect Technology Conference, pages 117-119, Jun. 5-7, 2000). 
     FIGS. 1 through 2  exemplify a conventional electrodeposition method and apparatus.  FIG. 1A  illustrates a substrate  10  having an insulator layer  12  formed thereon. Using conventional etching techniques, features such as a row of small vias  14  and a wide trench  16  are formed on the insulator layer  12  and on the exposed regions of the substrate  10 . In this example, the vias  14  are narrow and deep; in other words, they have high aspect ratios (i.e., their depth to width ratio is large). Typically, the widths of the vias  14  are sub-micronic. The trench  16  shown in this example, on the other hand, is wide and has a small aspect ratio. The width of the trench  16  may be five to fifty times or more greater than its depth. 
     FIGS. 1B-1C  illustrate a conventional method for filling the features with copper material.  FIG. 1B  illustrates that a barrier/glue or adhesion layer  18  and a seed layer  20  are sequentially deposited on the substrate  10  and the insulator  12 . The barrier layer  18  may be Ta, W, Ti, their alloys, their nitrides or combinations of them. The barrier layer  18  is generally deposited using any of the various sputtering methods, by chemical vapor deposition (CVD), or by electroless plating methods. Thereafter, the seed layer  20  is deposited over the barrier layer  18 . The seed layer  20  is typically copper if the conductor to be plated is also copper and may be deposited on the barrier layer  18  using various sputtering methods, CVD, or electroless deposition or their combinations. 
   In  FIG. 1C , after depositing the seed layer  20 , a conductive material layer  22  (e.g., copper layer) is partially electrodeposited thereon from a suitable plating bath or bath formulation. During this step, an electrical contact is made to the copper seed layer  20  and/or the barrier layer  18  so that a cathodic (negative) voltage can be applied thereto with respect to an anode (not shown). Thereafter, the copper material layer  22  is electrodeposited over the substrate surface using plating solutions, as discussed above. By adjusting the amounts of the additives, such as the chloride ions, the suppressor/inhibitor, and the accelerator, it is possible to obtain bottom-up copper film growth in the small features. 
   As shown in  FIG. 1C , the copper material  22  completely fills the via  14  and is generally conformal in the large trench  16 , because the additives that are used are not operative in large features. For example, it is believed that the bottom up deposition into the via  14  occurs because the suppressor/inhibitor molecules attach themselves to the top of the via  14  to suppress the material growth thereabouts. These molecules can not effectively diffuse to the bottom surface of the via  14  through the narrow opening. Preferential adsorption of the accelerator on the bottom surface of the via  14  results in faster growth in that region, resulting in bottom-up growth and the Cu deposit profile as shown in FIG.  1 C. Here, the Cu thickness that the bottom surface of the trench  16  is about the same as the Cu thickness t 2  over the insulator layer  12 . 
   As can be expected, to completely fill the trench  16  with the Cu material, further plating is required.  FIG. 1D  illustrates the resulting structure after additional Cu plating. In this case, the Cu thickness t 3  over the insulator layer  12  is relatively large and there is a step S 1  from the top of the Cu layer on the insulator layer  12  to the top of the Cu layer  22  in the trench  16 . For integrated circuit (IC) applications, the Cu layer  22  needs to be subjected to CMP or some other material removal process so that the Cu layer  22  as well as the barrier layer  18  on the insulator layer  12  are removed, thereby leaving the Cu layer only within the features  14  and  16 . These removal processes are known to be quite costly. 
   Methods and apparatus to achieve a generally planar Cu deposit as illustrated in  FIG. 1E  would be invaluable in terms of process efficiency and cost. The Cu thickness t 5  over the insulator layer  12  in this example is smaller than the traditional case as shown in  FIG. 1D , and the height of the step S 2  is also much smaller. Removal of the thinner Cu layer in  FIG. 1E  by CMP or other methods would be easier, providing important cost savings. 
   In co-pending U.S. application Ser. No. 09/201,929, entitled “METHOD AND APPARATUS FOR ELECTROCHEMICAL MECHANICAL DEPOSITION”, filed Dec. 1, 1998 and commonly owned by the assignee of the present invention, a technique is disclosed that achieves deposition of the conductive material into the cavities on the substrate surface while minimizing deposition on the field regions by polishing the field regions with a pad as the conductive material is deposited, thus yielding planar copper deposits. 
     FIG. 2A  shows a schematic depiction of a prior art electrodeposition system  30 . In this system, a wafer  32  is held by a wafer holder  34  with the help of a ring clamp  36  covering the circumferential edge of the wafer  32 . An electrical contact  38  is also shaped as a ring and connected to the (−) terminal of a power supply for cathodic plating. The wafer holder  34  is lowered into a plating cell  40  filled with plating electrolyte  42 . An anode  44 , which makes contact with the electrolyte  42 , is placed across from the wafer surface and is connected to the (+) terminal of the power supply. The anode  44  may be made of the material to be deposited, i.e., copper, or of an appropriate inert anode material such as platinum, platinum coated titanium or graphite. A plating process commences upon application of power. In this plating system, the electrical contact  38  is sealed from the electrolyte and carries the plating current through the circumference of the wafer  32 . However, the presence of the contact  38  and the clamp  36  at the circumference of the wafer  30  is an important drawback with this system and increases the edge exclusion indicated by ‘EE’ in FIG.  2 A. As a result of edge exclusion, a very valuable prime area on the surface of the wafer  32  is lost. 
     FIGS. 1A through 1E  show how the features on the wafer surface are filled with copper. For this filling process to be efficient and uniform throughout the wafer, it is important that a uniform thickness of copper be deposited over the whole wafer surface. Thickness uniformity needs to be very good because non-uniform copper thickness causes problems during the CMP process. As shown in  FIG. 2B , in order to improve uniformity of the deposited layers, shields  46  may be included in prior art electroplating systems such as that shown in FIG.  2 A. In such systems, either the wafer  32  or the shield  46  may be rotated. Such shields are described, for example, in U.S. Pat. No. 6,027,631 to Broadbent, U.S. Pat. No. 6,074,544 to Reid et al. and U.S. Pat. No. 6,103,085 to Woo et al. 
   In view of the foregoing, there is a need for alternative electrodeposition processes and systems which minimize edge exclusion problems and deposit uniform conductive films. 
   SUMMARY OF THE INVENTION 
   The present invention involves depositing a conductive material on an entire surface of a semiconductor wafer through an electrodeposition process. Specifically, the present invention provides a method and a system to form a substantially flat conductive material layer on an entire surface of a semiconductor wafer without losing any space on the surface for electrical contacts, i.e., without wafer edge exclusion. 
   In one aspect of the present invention, a process for depositing materials on a surface of a wafer, without excluding any region for electrical contacts on the surface wherein the wafer has a maximum lateral dimension, is provided. The process includes the steps of providing an anode, supporting a shaping plate between the anode and the surface of the wafer, flowing an electrolyte through the shaping plate and between the anode and the surface of the wafer, contacting a contact region of the surface of the wafer with a contact member, and applying a potential difference between the anode and the contact member. 
   A shaping plate can be supported between the anode and the surface of the substrate such that an upper surface of the shaping plate faces a surface of the wafer. The shaping plate includes a plurality of openings such that each opening puts the surface of the wafer in fluid communication with the anode. The shaping plate has a lateral dimension that is longer than the maximum lateral dimension of the wafer. The contact members contact contact regions on the surface of the wafer outside of a “recessed” edge of the shaping plate and thereby make electrical contact to the surface of the wafer. When the potential difference is applied between the anode and the contact member, material deposition on a deposition region of the surface of the wafer through the shaping plate occurs when the wafer is in a first position. By moving the wafer into a second position while contacting the contact region with the contact member, material deposition on both the contact regions and the deposition region occurs. 
   According to another aspect of the present invention, a system for depositing materials on a surface of a wafer having a maximum lateral dimension is provided. The system includes an anode, a shaping plate defining a recessed edge, a liquid electrolyte contained between the anode and the surface of the substrate, and an electrical contact member for contacting a contact region on the surface of the substrate outside of the recessed edge of the shaping plate. 
   The shaping plate can be supported between the anode and the surface of the wafer such that an upper surface of the shaping plate faces the surface of the wafer. The shaping plate includes a plurality of openings. The upper surface of the shaping plate has a lateral dimension that is longer than the maximum lateral dimension of the wafer. The liquid electrolyte flows through the openings of the shaping plate and against the surface of the wafer such that the electrolyte always contacts a first region of the surface of the wafer. The electrical contact member establishes electrical contact with a second region of the surface of the wafer outside of the recessed edge of the shaping plate. The second region intermittently contacts the electrolyte when the wafer is rotated over the shaping plate. 
   According to still another aspect of the invention, a system by which conductive material can be deposited out of an electrolyte onto a surface of a semiconductor substrate includes an assembly by which the electrolyte is supplied to the surface of the substrate during deposition of the material, and an anode which is contacted by the electrolyte during this deposition. At least one contact is electrically interconnected with the surface at a selected area of the surface during the deposition. Deposition of the material progresses discontinuously on the selected area and continuously on the rest of the surface as at least one of the contact and the surface moves with respect to the other during application of a potential difference between the anode and the contact. 
   A device which alleviates non-uniformity between deposition of the material on the selected area and on the rest of the surface can be provided. The device can include a shield, with openings defined therein, disposed between the anode and the surface to alter an electric field distribution. Alternatively, the device can include a perforated plate provided between the anode and the surface with asperity regions having different degrees of open area. 
   The assembly by which electrolyte is supplied may include a cup defining a cavity through which the electrolyte flows during deposition of the conductive material. The anode can be received in the cavity, while the contact is disposed outside of said cavity. The assembly further includes an inlet for supplying the electrolyte to the cavity. 
   A rotatable, and preferably translatable, carrier holds the substrate during deposition of the conductive material so as to move the surface of the substrate with respect to the contact. 
   The shaping plate can be disposed between the anode and the surface during depositing of the conductive material. The shaping plate is porous and permits through flow of the electrolyte. 
   If the polarity of the system is reversed, the system may be used to remove material, by electroetching, in a uniform manner from the wafer or substrate surface instead of depositing the material. In this case, the plating electrolyte may be replaced with a commonly known electroetching or electropolishing solution. Also, in this case, the anode may be replaced with an inert electrode made of inert material. 
   These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description, and claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a schematic view of a semiconductor substrate having an isolation structure formed on top of the substrate wherein the isolation structure has been etched to form trench and via features on the substrate; 
       FIG. 1B  is a partial cross-sectional view of the substrate shown in  FIG. 1A  wherein a barrier layer and seed layer have been formed on the features and the isolation or insulator layer; 
       FIG. 1C  is a schematic view of the structure shown in  FIG. 1B  wherein a conventional conformal layer has been partially deposited on the seed layer; 
       FIG. 1D  is a schematic view of the structure shown in  FIG. 1C  wherein the layer has been fully deposited; 
       FIG. 1E  is a schematic view of the structure shown in  FIG. 1D  wherein a more planar layer has been formed; 
       FIG. 2A  is a schematic view of a prior art electrodeposition system; 
       FIG. 2B  is a schematic view of another prior art electrodeposition system utilizing shields; 
       FIG. 3  is a schematic view of an embodiment of a system of the present invention for depositing a conductive material on a full face of a wafer without excluding any edge regions; 
       FIG. 4  is a schematic view of the system shown in  FIG. 3  showing positions of the electrical contacts and contact regions on the wafer relative to the width of a peripheral side wall of an anode cup of the present invention; 
       FIG. 5  is a partial plan view of the system shown in  FIG. 3  showing intermittent and continuous deposition regions on the wafer; 
       FIG. 6  is a schematic view of the system of the present invention shown in  FIG. 3  including shields placed between an anode and cathode of the system; 
       FIG. 7  is schematic view of another embodiment of a system of the present invention for depositing conductive materials on a full face of a wafer without excluding any edge regions; 
       FIG. 8  is a partial schematic view of the system in  FIG. 7  showing a wafer carrier assembly and a shaping plate of the present invention; 
       FIG. 9A  is a plan view of the shaping plate having a wafer positioned above the shaping plate wherein the wafer has continuous and intermittent deposition regions; 
       FIG. 9B  is a schematic cross sectional view of the shaping plate showing continuous asperities through the shaping plate; 
       FIG. 9C  is a schematic view of another embodiment of the shaping plate of the present invention wherein the shaping plate has two regions with differing opening densities; 
       FIG. 10A  is a schematic side view of the electrodeposition system of the present invention showing the position of the wafer electrical contacts on the contact regions relative to the width of the shaping plate of the present invention; 
       FIG. 10B  is another schematic side view of the electrodeposition system of the present invention showing the position of the wafer along the length of the shaping plate of the present invention; 
       FIG. 11A  is a highly magnified cross sectional view of a wafer having via and trench features covered with a seed layer prior to a deposition process of the present invention; 
       FIG. 11B  is a schematic view of the structure shown in  FIG. 11A , wherein the a deposition layer has been electrodeposited using the present invention; and 
       FIG. 11C  is a schematic view of the structure shown in  FIG. 11B  wherein the deposition layer has been deposited in a planar manner. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention involves depositing a conductive material on an entire surface or full face of a semiconductor substrate or wafer through an electrodeposition process. As will be described below, the present invention provides a method and a system to form a substantially flat conductive material layer on the entire surface of a semiconductor substrate without losing any space on the surface for electrical contacts, i.e., without wafer edge exclusion. The full face deposition process of the present invention advantageously achieves deposition of a conductive material in a plurality of cavities, such as trenches, vias, contact holes and the like, on an entire surface of a semiconductor wafer. In one embodiment, the present invention employs a shaping cup or an anode cup and delivers the electrolyte directly onto the surface of the wafer so as to deposit conductive material onto the surface of the wafer. In another embodiment, the conductive material is deposited through a perforated plate. In this embodiment, the perforated plate facilitates uniform deposition of the conductive material. In yet another embodiment, the present invention achieves deposition of the conductive material through the perforated plate into the features of the surface of the wafer while minimizing the deposition on the top surface regions between the features by contacting, sweeping and polishing of the surface with the perforated plate of the present invention. 
   The process of the present invention exhibits enhanced deposition characteristics resulting in layers having flatness previously unattainable and conductive layers with materials characteristics surpassing that of prior art layers that have been produced using prior art processes and devices. 
   Reference will now be made to the drawings wherein like numerals refer to like parts throughout. As shown in  FIG. 3 , in one embodiment, an electrodeposition system  50  of the present invention may preferably comprise an upper portion  51  and a lower portion  52 . In the preferred embodiment, the system  50  may be used to deposit a conductive material such as copper on a semiconductor wafer such as a silicon wafer. It should be noted, however, that although copper is used as an example, the present invention may be used for deposition of other common conductors such as Ni, Pd, Pt, Au and their alloys. The upper portion  51  of the electrodeposition system  50  may be comprised of a carrier assembly having a wafer carrier  53 , shown in  FIG. 3  holding an exemplary wafer  54 , which is attached to a carrier arm  55 . 
   The lower portion  52  of the system  50  may be comprised of an anode assembly comprising an anode  56  which is preferably placed into an enclosure such as an anode cup  57  or a shaping cup. The anode cup  57  may comprise an inner cavity  58  or housing defined by a peripheral side wall  59  raised above a bottom wall  60 . An upper rim frame  61  of the peripheral side wall  59  forms the upper end of the anode cup  57 . In this embodiment, the upper rim frame  61  is preferably rectangular in shape and the plane of the rim frame is adapted to be substantially parallel to the wafer  54  when the wafer carrier  53  is lowered toward the rim frame  61 . As shown in  FIG. 5 , the rim frame has a maximum lateral dimension D. A copper plating electrolyte  62  may be pumped into the anode cup  57  through a liquid inlet  63  formed in the bottom wall  60  in the direction of arrow  264 . The anode cup and the inlet thus form at least part of an assembly by which the electrolyte  62  can be supplied to a front surface of a semiconductor wafer or substrate. During the electrodeposition process, the anode cup  57  is entirely filled with electrolyte  62  up to the rim frame  61 . The anode  56  is electrically connected to a positive terminal of a voltage source (not shown) through an anode connector  64 . During the electrodeposition process, the wafer  54  is kept substantially parallel as well as in close proximity to the rim frame  61  and rotated. By controlling the flow rate of the electrolyte  62 , the electrolyte makes contact with a front surface  65  of the wafer which is in close proximity. Excess electrolyte flows down over the peripheral side walls  59  and is collected for recycling. 
   In this embodiment, it is understood that electrical contact members  66  contact or otherwise electrically interconnect with wafer  54  on contact regions  67  of the front surface  65 . The position of the contact regions  67  vary circularly with respect to the rim frame  61  as the wafer  54  is rotated over anode cup  57 . The contact members  66  are connected to a negative voltage source (not shown) using the connectors  68 . 
   As shown in  FIG. 4 , the wafer carrier  53  holds the wafer  54  from a back surface  69  of the wafer  54  and against a chuck face of the wafer carrier  53 . The wafer  54  may be retained using vacuum suction or a retaining ring  70  (shown in  FIG. 4 ) or both, thereby fully exposing a front surface  65  and the contact regions  67  of the wafer  54 . In accordance with the principles of the present invention, the wafer  54  defines a maximum lateral dimension d, which is the diameter of the wafer in this case. Alternatively, the retaining ring  70  may be an integral part of the wafer carrier  53 . During the process, the wafer carrier  53  and hence the wafer  54  may be rotated by rotating the carrier arm  55  about a rotation axis  71  or vertical axis of the wafer carrier  53  in a rotation direction  72 . As will be described more fully below, the rotation motion moves contact regions  67  over the electrolyte  62  and exposes the contact regions  67  to the electrolyte. The combined effect of both the full exposure of the front surface  65  of the wafer  54  and the ability to expose the contact regions  67  to the electrolyte  62  by moving them over the anode cup  57  results in zero edge exclusion on the wafer  54 . 
   As shown in  FIGS. 4 and 5 , in this embodiment, the peripheral side wall  59  of the shaping cup or the anode cup  57  may be generally shaped as a rectangular side wall which may comprise a first side wall  73 , a second side wall  74 , a third side wall  75  and a fourth side wall  76 . In this embodiment, the first and second side walls  73 ,  74  may be longer in length than the length of the third and fourth side walls  75 ,  76  and form “recessed” edges  77  of the peripheral side wall  59 , i.e., edges which are recessed with respect to the circumferential outer edge of the wafer  54 . The third and fourth side walls  75 ,  76  form lateral edges  78  of the peripheral side wall of the anode cup  57 . In this embodiment, the width of the anode cup  57  or the distance between the recessed edges  77  is adapted to be smaller than the diameter of the wafer  54 , which is the maximum lateral distance d of the wafer, while the length of the anode cup or the distance between the lateral edges, which is the maximum lateral distance D of the rim frame  61 , is adapted to be longer than the diameter of the wafer. 
   Due to the difference between the maximum lateral distance d and the width of the upper rim frame, this configuration exposes contact regions  67  on the wafer  54  and allows placement of the electrical contact members  66  on the contact regions  67 . Although in this embodiment the recessed edges  77  are straight, it is within the scope of the present invention that the recessed edges  77  may be formed depressed, V-shaped, or in any other possible configuration that allows placement of electrical contacts on the front surface  65  of the wafer. It should be noted that, at any given instant, the contact regions  67  on the wafer  54  can only be plated with copper when the contact regions  67  are rotated over the electrolyte  62 . In this respect, as the wafer  54  is rotated, a first area  79 , which is shown by a dotted circle in  FIG. 5 , always stays over the anode cup and is plated continuously. However, in a selected, second, area  80  of the surface, which is outside the first area  79  and is defined by the contact regions, the deposition process progresses in a discontinuous manner. Therefore, the deposition rate in the first area  79  and the deposition rate in the second area  80  differ and thus the second area  80  may have a thinner deposition layer. 
     FIG. 6  shows how this non-uniformity in the deposition layer may be alleviated by the use of shields  82 . The shields  82  are immersed into the electrolyte and positioned adjacent to the first area  79  in the manner shown in  FIG. 6 , although, alternatively, they may rest on the anode  56 , if the anode to cathode (wafer) distance is reduced. The shields  82  may have holes  99  or openings in them. The shields alter the electric field distribution between the anode and the first area  79  (see  FIG. 5 ) or the contact regions  67  on the wafer  54  and vary the deposition rate on the first area  79 , thereby modifying the thickness profile of the electrodeposited copper across the front surface  65  of the wafer. In this embodiment, the shields  82  may be made of a non-conductive material such as a polymer material. 
   Referring back to  FIGS. 4 and 6 , in use, the electrolyte is pumped into the anode cup  57  in the direction of the arrow  264 . Once the electrolyte fills the anode cup  57 , with the applied pressure, the electrolyte reaches the front surface  65  of the wafer  54  in the direction of the arrows  81 . As previously mentioned, the front surface  65  of the wafer  54  is retained at close proximity to the electrolyte. The gap between the front surface  65  of the wafer  54  and the electrolyte surface can be adjusted by vertically moving the carrier assembly  53  along the axis  71 . Subsequent to the adjustment of the distance between the front surface  65  and the electrolyte, the electrodeposition process is initiated by applying a potential difference between the anode  56  and the contract members  66 . Accordingly, at this stage, the potential difference is selected such that the contact members become more cathodic (−) than the anode. Further, since the contact members touch the front surface  65  of the wafer  54 , the front surface  65  is also rendered cathodic. As the deposition process progresses, copper uniformly deposits on the front surface  65 . As preciously mentioned, the contact regions on the wafer  54  can only be plated with copper when the contact regions  67  are rotated over the electrolyte  62  and hence exposed to the electrolyte. Overflowing electrolyte which is depicted by arrows  82  may be collected and recycled. 
   As shown in  FIG. 7 , in another embodiment, an electrodeposition system  100  of the present invention may preferably comprise an upper portion  102  and a lower portion  104 . In the preferred embodiment, the system  100  may be used to deposit a conductive material such as copper on a semiconductor wafer such as a silicon wafer. As in the previous embodiment, although copper is used as an example, the present invention may be used for deposition of other common conductors such as Ni, Pd, Pt, Au and their alloys. The upper portion  102  of the electrodeposition system  100  may be comprised of a carrier assembly having a wafer carrier  106 , shown in  FIG. 7  holding an exemplary wafer  108 , which is attached to a carrier arm  110 . The carrier arm may rotate or move the wafer  108  laterally or vertically. 
   The lower portion  104  of the system  100  may be comprised of an anode assembly comprising an anode  112 , preferably a consumable copper anode, and a shaping plate  114 . The anode may preferably be placed into an enclosure such as an anode cup  116  and enclosed by an anode plate  118  upon which the shaping plate  114  may be placed. The shaping plate  114  and the anode plate  118  are both preferably perforated plates. The shaping plate  114  may comprise a plurality of openings  120  or asperities. The openings  120  are adapted to generally match with the openings (see  FIGS. 10A and 10B ) in the anode plate  118  so that when they are attached together, corresponding openings form channels allowing electrolyte to flow through the plates  114  and  118  and wet the front surface of the wafer  108  during the electrodeposition process. During the electrodeposition process, the wafer  108  may be kept substantially parallel to an upper surface  119  of the shaping plate  114  and rotated. The wafer may also be moved laterally. A copper plating electrolyte is pumped into the anode cup  116  through a liquid inlet  121  in the direction of arrow  122 . Again, therefore, the anode cup and the inlet form at least part of an assembly by which the electrolyte can be supplied to a front surface of a semiconductor wafer or substrate. The anode  112  is electrically connected to a positive terminal of a voltage source (not shown) through an anode connector  124 . It should be noted that if the shaping plate  114  is made of a rigid material, the anode plate  118  may not be needed. 
   As will be described more fully below, in this embodiment, electrical contact members  126  contact or otherwise electrically interconnect with the wafer  108  on contact regions  128 . The position of the contact regions  128  varies circularly with respect to the shaping plate  114  as the wafer  108  is rotated or moved over the shaping plate  114 . The contact members are connected to a negative terminal of the voltage source (not shown) using the connectors  129 . 
   As shown in  FIG. 8 , the wafer carrier  106  holds the wafer  108  from a back surface  130  of the wafer  108 . The wafer  108  may be held on a lower face  131  or a chuck face of the wafer carrier  106  as in the manner shown in FIG.  8 . In this embodiment, the wafer is held using vacuum suction or a retaining ring  133  (shown in FIG.  8 ), or both, thereby fully exposing a front surface  132  of the wafer  108  to the electrolyte. Alternatively, the retaining ring  133  may be an integral part of the wafer carrier  106 . During the process, the wafer carrier  106  and hence the wafer  108  may be rotated by rotating the carrier arm  110  about a rotation axis  134  or vertical axis of the wafer carrier  106  in a rotation direction  135 . As will be described more fully below, the rotation motion advantageously moves contact regions  128  over the shaping plate  114  and exposes the contact regions  128  to the electrolyte flowing through the shaping plate (see FIG.  7 ). The combined effect of both the full exposure of the front surface  132  of the wafer  108  and the ability to continuously expose the contact regions  128  to the electrolyte by moving them over the shaping plate  114  results in zero edge exclusion on the wafer  108 . 
   As shown in  FIGS. 9A-9B , in this embodiment, the shaping plate  114  of the present invention is generally shaped as a rectangle defined by a first side wall  136 , a second side wall  138 , a third side wall  140  and a fourth side wall  142 . In this embodiment, the first and second side walls  136 ,  138  may be longer than the third and fourth side walls  140 ,  142  and form “recessed” edges  144  of the shaping plate  114 , i.e., edges which are recessed with respect to the circumferential outer edge of the wafer  108 . The third and fourth side walls  140  and  142  form lateral edges  146  of the shaping plate  114 . The width of the shaping plate  114  or the distance between the recessed edges is configured to be smaller than the diameter d of the wafer  108 . Similar to the previous embodiment, the distance between the lateral edges  146  is the maximum lateral dimension D of the shaping plate  114 . Further, the diameter of the wafer is the maximum lateral dimension d of the wafer  108 . Although in the preferred embodiment the shaping plate  114  is shaped as a rectangle, the shaping plate may be given any geometrical form. 
   As shown in  FIG. 9A , the difference between the lateral distances d and the width of the shaping plate exposes contact regions  128  on the wafer  108  and further allows placement of the electrical contact members  126  on the contact regions  128  (see FIG.  7 ). Although in this embodiment the recessed edges are straight in shape, it is within the scope of the present invention that the recessed edges may be formed depressed, V-shaped or in any other possible configuration that allows placement of electrical contacts on a front surface of a wafer. By choosing the width and length of the shaping plate  114  as described above, the contact regions  128  can be contacted by or otherwise electrically interconnected with the electrical contact members  126  as the wafer  108  is moved in a first direction  147  over the shaping plate  114 . In  FIG. 9A , the contact members are shown as linear strips which would touch the contact regions  128 . However, it should be noted that, at a given instant, the contact regions  128  on the wafer can only be plated with copper when the contact regions are rotated over the asperities of the shaping plate  114 . In this respect, as the wafer is rotated, a first area  148 , which is shown by a dotted circle in  FIG. 9A , always stays over the shaping plate  114  and is plated continuously. However, in a second, selected, area  149 , which is outside the first area  148  and is defined by contact regions, the deposition process progresses in a discontinuous manner. Therefore, the deposition rate in the first area  148  and the deposition rate in the second area  149  differ and thus the second area  149  is expected to have a slightly thinner deposition layer. As will be described below, this difference in thickness can be eliminated using alternative asperity designs. Additionally, shields  82  as described above and shown in  FIG. 6  can be used with this embodiment to provide a uniform deposition layer across the front surface  132  of the wafer  108 . 
   Referring to  FIG. 9B , the asperities  120  are defined by an inner side wall  150  extending between an upper opening  152  in the upper surface  119  and a lower opening  154  in a bottom surface  156  of the shaping plate  114 . As previously mentioned, during the electrodeposition process, the electrolyte solution reaches the front surface of the wafer through the asperities  120 . Depending on the functionality of the shaping plate  114 , the shaping plate  114  may be made of an insulating material or a conductive material. If only electrodeposition is carried out, the shaping plate may be made of a conductive material. However, if the electrodeposition and polishing are performed together, an insulating material, such as a polymeric or a ceramic material, is preferred. Although in this embodiment the asperities  120  have rectangular shapes, they may be shaped in various geometrical forms such as oval, square, circular or others. The shape and the volumetric space and the density of the asperities  120  define the uniformity of the deposited film. The inner side walls  150  of the asperities  120  do not need to be perpendicular to the upper and bottom surfaces  119  and  156 , i.e., they can be slanted, curved or in other forms or shapes. 
     FIG. 9C  shows an alternative embodiment of the shaping plate  114 . In this embodiment, the shaping plate  114  comprises first and second asperity regions  157  and  158  respectively. Due to its design, the second asperity region  158  has a higher degree of open area than the first asperity region  157 , which results in higher copper deposition on the wafer. When the wafer is plated by oscillating it around position A in the first region  157 , a certain deposition layer thickness profile can be obtained and the thickness of the deposited layer may be slightly thinner along the contact regions  128 . In order to bring up the thickness along the contact regions  128 , the wafer can be moved to position B, and partially over the second region  158 , so as to expose contact regions  128  to higher copper deposition rate. This step may be carried out during a part of the electrodeposition process so that a uniform deposition profile of the depositing copper layer is achieved. It is also within the scope of the present invention that such high density areas can be formed at one or more locations on the shaping plate  114  and the thickness profile of the depositing layer can be changed or controlled at will. That is, the thickness profile across a front surface of a wafer can be made concave, convex, or entirely flat. With this embodiment, the edge exclusion can be made zero, i.e., the entire wafer front surface can be uniformly plated all the way to its edge. 
   As shown in  FIGS. 10A and 10B , the shaping plate  114  is placed on the anode plate  118  having a plurality of holes  159 . The holes  159  in the anode plate  118  and the asperities  120  in the shaping plate  114  form continuous electrolyte channels  160  connecting an inner cavity  162  of the anode cup  116 , which is filled with electrolyte during the process, to the upper surface  119  of the shaping plate  114 . Electrolyte enters the anode cup in the direction of arrow  122  and flows through the channels  160  in the direction of arrows  164 . There may be filters (not shown) placed in the inner cavity  162  to catch the particles generated by the dissolution of the anode  112  during electroplating. The anode plate  118  may be made of an insulating material or a conductive material. For the systems not using a consumable anode, the anode plate  118  may be used as anode or another inert cathode can be put in place of the anode  112 . In such systems, the anode plates can be made of a metal such as titanium and can preferably be coated with an inert metal such as platinum. Accordingly, the positive voltage is connected to the anode plate rather than to the consumable anode, such as a copper anode in the case of present invention. 
     FIG. 10A  also shows the position of the contact members  126  contacting contact regions  128 . The contact members may be manufactured in a variety of configurations such as brushes, pins, rollers, flat surfaces and the like. The contact members should be well isolated from the anode, and are preferably stationary with the contact regions sliding over them. The contact members may also move with the wafer. The contact members are preferably made of or coated with flexible and corrosion resistant conductive materials such as platinum, ruthenium, rhodium and nitrides of refractory materials and such. As previously mentioned and shown in  FIG. 10A , since no conventional clamp is used to establish electrical contact with the front surface  132  of the wafer  108 , edge exclusion during deposition is advantageously reduced down to zero. Possible scratching of the contact areas by contact members can be avoided or minimized by assuring that the force applied by the contact members against the contact regions is minimal. 
   Referring back to  FIG. 10A , in the process of the preferred embodiment, the electrolyte is pumped into the inner cavity  162  of the anode cup  116  of the electrodeposition system  100  in the direction of the arrow  122 . Once the electrolyte fills the inner cavity  162 , the electrolyte reaches the front surface  132  of the wafer  108  in the direction of the arrow  164  by flowing through the holes  159  in the anode plate  118  and then the asperities  120  in the shaping plate  114 . Referring now to  FIGS. 10A-10B , the front surface  132  of the wafer  108  may be held at a first position along the axis  134 , preferably at close proximity, for example 0.25-5 millimeters distance, to the shaping plate  114 . The gap between the front surface  132  of the wafer  108  and the shaping plate  114  can be adjusted by vertically moving the carrier assembly  102  along the axis  134 . Subsequent to the adjustment of the distance between the front surface  132  and the upper surface of the shaping plate  114 , the electrodeposition process is initiated by applying a potential difference between the anode  112  and the contact members  126 . Accordingly, at this stage, the potential difference is such selected that the contact members become more cathodic (−) than the anode. Further, since the contact members touch the front surface  132  of the wafer  108 , the front surface  132  is also rendered cathodic. 
   At this point, details of the electrodeposition process employing the system  100  of the present invention may be further described with help of  FIGS. 11A and 11B .  FIG. 11A  exemplifies a surface portion  166  of the front surface  132  of the wafer  108  (see  FIG. 8 ) prior to the electrodeposition process. The surface portion  166  may comprise a via feature  168  or a narrow hole and a trench  170  or a larger hole. The via feature  168  and the trench feature  170  may be formed in an insulator layer  172  that is formed on a substrate  174  which may be part of the wafer  108  or be formed on the wafer  108 . The features  168  and  170  expose active device locations  176  on the substrate  174 . 
   Referring to  FIG. 10B , once the potential difference is applied, copper is plated onto the front surface  132  while the wafer  108  is rotated in the rotational direction  135  and moved linearly in the first direction  147  over the shaping plate  114  as in the manner shown in FIG.  10 B. The first direction  147  is preferably parallel to the recessed edges  144  and perpendicular to the lateral edges  146 . Although the linear motion in the first direction  147  may preferably be from about 5 millimeters to 100 millimeters depending upon the size of the wafer, longer linear motions are within the scope of this invention and can be utilized. In this respect, the rotation of the wafer  108  may be from approximately 1 rpm to 250 rpm. Although, it is preferable to move the wafer in lateral direction, it should be understood that the wafer may be rotated and the anode assembly may be moved laterally to obtain a similar motion between the wafer and the shaping plate. As shown in  FIG. 11B , as the deposition process progresses, a deposition layer  180  is uniformly formed on the copper seed layer  178  and fills the via and trench features  168  and  170 . As previously mentioned, the copper seed layer  178  may be formed on top of a barrier layer. As also previously mentioned, by rotating wafer  108 , non-uniformity of the depositing layer will be minimized. The contact regions  128  on the wafer can only be plated with copper when the contact regions  128  are rotated over the asperities  120  of the shaping plate  114  and hence exposed to the electrolyte. 
   Referring to  FIG. 10B , to deposit planar films, the gap between the shaping plate  114  and the front surface of the wafer  108  may be reduced to zero and the front surface  132  is contacted with the upper surface  119  of the shaping plate  114  by moving the carrier assembly  102  and the wafer  108  vertically along the axis  134  into a second position. In this case the shaping plate may be made of a polishing pad. Alternatively, the anode assembly  104  may be vertically moved along the axis  134 , if the assembly is equipped for such movement. In this second position, as the wafer  108  is rotated and moved along the first direction  147 , the wafer  108  touches and rubs against the shaping plate  114  while the deposition process continues. As shown in  FIG. 11C , this, in turn, forms a planarized layer  182  by minimizing the thickness of the deposition layer  180  on the tops of the insulating layer  172  whereas deposition of material in the features  168  and  170  is unimpeded. 
   If the polarity of the system is reversed, the system  100  may be used to remove material (electroetching) in a uniform manner from a wafer surface instead of depositing it in a uniform manner. In this case, the plating electrolyte may be replaced with a commonly known electroetching or electropolishing solution. The Cu anode may be replaced with an inert electrode made of inert material such as Pt, Ti or Pt coated Ti materials. 
   It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.