Abstract:
Electroplating systems that include a plurality of electrodes, a power supply operably coupled to the plurality of electrodes, a platen for bearing a substrate on which metal features are to be formed, and an electrode support are disclosed. The electrode support may be configured for suspending the electrode assembly over an upper surface of the substrate disposed on the platen in spaced relation to and in alignment with the substrate or for supporting the electrode assembly in a stationary position over the substrate when the voltage is applied across the plurality of electrodes. The electrodes may be adjacent, mutually spaced and electrically isolated and connected in series so as to be oppositely polarized when the voltage is applied thereacross or may be connected so as to have alternating polarities when the voltage is applied thereacross.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/234,783, filed Sep. 22, 2008, now U.S. Pat. No. 8,419,906, issued Apr. 16, 2013, which is a divisional of U.S. patent application Ser. No. 10/933,823, filed Sep. 2, 2004, now U.S. Pat. No. 7,435,324, issued Oct. 14, 2008, and is also related to U.S. patent application Ser. No. 11/516,065, filed Sep. 6, 2006, now U.S. Pat. No. 7,708,875, issued May 4, 2010. The disclosure of each of which is hereby incorporated herein in its entirety by this reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to electrochemical deposition of a metal film. More specifically, the present invention relates to a noncontact method of selectively electrochemically depositing metal features of a desired size and shape and at desired locations on a surface of a substrate, such as a semiconductor substrate. 
     BACKGROUND 
     To fabricate integrated circuits, multiple conductive layers are formed on semiconductor substrates to provide electrical contact between conductive components on the semiconductor devices. Since the dimensions of semiconductor devices have dropped below one micron design rules, the conductive layers are used to accommodate higher densities. The conductive layers are typically metal layers or metal features that are formed by chemical vapor deposition (“CVD”), physical vapor deposition (“PVD”), atomic layer deposition (“ALD”), or other electrodeposition techniques, such as electroplating or electroless deposition. To electroplate the metal feature, a seed layer is formed on a surface of the semiconductor substrate. The semiconductor substrate is directly attached to a positive electrode and a negative electrode. The surface of the semiconductor substrate is then plated with a desired metal by applying a voltage through the electrodes while an electrolyte solution containing the metal to be plated is flowed over the semiconductor substrate. The metal is electroplated onto the entire surface of the semiconductor substrate. 
     Electroplating is commonly used to form interconnect lines and vias in multilayer metal structures in a damascene process. Electroplating the interconnect lines and vias is one of many steps in fabricating the integrated circuits. In the damascene process, trenches are formed in the semiconductor substrate and are filled with a metal, such as copper, aluminum, or tungsten. After the metal is plated, the semiconductor substrate is polished, leaving the metal interconnect in the trench areas. One disadvantage with the damascene process is that since the entire surface of the semiconductor wafer is covered with the metal, undesired portions of the metal must be removed by polishing. A second disadvantage is that the metal is deposited nonuniformly on the semiconductor substrate because the electrodes are connected to edges of the semiconductor wafer, which causes a drop in potential towards the center of the semiconductor wafer. 
     Bipolar electrochemical processes have also been developed in which the desired metal is deposited on the semiconductor substrate without contact between the electrodes and the semiconductor substrate. For instance, U.S. Pat. No. 6,120,669 to Bradley discloses a bipolar electrochemical process that is used to toposelectively deposit a metal, such as a metal wire, between two metal particles. In addition, a method of plating metal interconnections on a semiconductor wafer using a bipolar electrode assembly is disclosed in U.S. Pat. No. 6,132,586 to Adams et al. A metallized surface of the semiconductor wafer is positioned opposite an anode and cathode of the bipolar electrode assembly. An electroplating solution of a metal to be plated is then flowed between the anode and a cathode and the metallized surface of the semiconductor wafer. A voltage is applied between the electrodes to plate the metal on the metallized surface of the semiconductor wafer. Relative motion is also provided between the bipolar electrode assembly and the semiconductor wafer while the voltage is applied. By moving the bipolar electrode assembly over the surface of the semiconductor wafer, electroplating of the metal is localized to a small area on the semiconductor wafer surface and provides more uniform deposits. The bipolar electrode assembly also enables one side of the semiconductor wafer to be simultaneously plated and deplated (electropolished). By applying a positive potential through the anode and a negative potential through the cathode, an area under the anode is electroplated while the area under the cathode is deplated. 
     BRIEF SUMMARY 
     The present invention relates to a method of selectively electroplating metal features on a semiconductor substrate. Exemplary metal features may include bond pads, redistribution layers or other traces, damascene structures and interconnects for same, and other conventional metal features found in semiconductor devices, which are formed presently by other techniques. The method comprises providing an electrode assembly that includes a plurality of adjacent, mutually spaced and electrically isolated electrodes connected in series so as to be oppositely polarized when a voltage is applied thereacross. As used herein, the terms “positive” and “negative” are respectively used to identify individual electrodes exhibiting that given polarity at a particular time. An insulating material may also be interposed between each of the plurality of electrodes. The electrode assembly is positioned over a conductive surface of a substrate and an electrolyte solution is applied to the substrate surface. The electrode assembly and the substrate surface may be positioned in close proximity to one another with the plurality of electrodes to be of positive polarity positioned over, but not in contact with, the surface at locations where the metal features are to be formed. A DC voltage may be applied to the electrode assembly, which may generate a fringe electric field that passes through the conductive surface of the substrate between adjacent positive and negative electrodes of the plurality. The fringe electric field may cause negatively charged cathodic portions to form on the substrate surface beneath the plurality of positive electrodes and positively charged anodic portions to form on the conductive surface of the substrate beneath the plurality of negative electrodes. A metal film is deposited from the electrolyte solution on the negatively charged cathodic portions of the conductive surface of the substrate that are positioned beneath the plurality of positive electrodes in a configuration corresponding to that of the positive electrodes, while portions of the substrate surface that are positioned beneath the plurality of negative electrodes may remain unplated. Instead of a DC voltage, an AC voltage may also be applied to the electrode assembly, thus varying the polarity of each electrode with each voltage cycle and reversal of polarity, by which metal features may be deposited beneath each electrode as it is caused to exhibit a positive polarity. The metal film may comprise any of nickel, copper, cobalt, platinum, aluminum, silver, gold, chromium, iron, zinc, cadmium, palladium, platinum, tin, and bismuth. 
     The present invention also relates to an electroplating system that comprises a plurality of adjacent, electrically isolated electrodes connected in a series so as to be oppositely polarized when a voltage is applied thereacross. A power supply is placed in communication with the plurality of electrodes, which may be insulated from each other by an interposed insulating material, such as an epoxy. The plurality of electrodes may, in combination, be configured to produce a fringe electric field when a voltage is applied thereto by connecting the plurality of electrodes to the power supply in an alternating polarity pattern. The power supply may be an AC power supply or a DC power supply. As noted above, if an AC power supply is used and an AC voltage is applied to the electrodes of the assembly, each electrode is alternately of positive and negative polarity, enabling metal deposition beneath each electrode. 
     The electroplating system may also include a chuck or platen on which a substrate having a conductive surface upon which metal features are to be selectively plated is supported. The electrode assembly is supported using an electrode support over the chuck or platen in selected alignment in the horizontal (X-Y) plane and rotationally about a vertical (Z) axis perpendicular thereto with the substrate and, more specifically, with semiconductor die locations thereon. The conductive surface of the substrate may be positioned in close proximity to the electrode assembly, such as from approximately 0.1 mm to approximately 1 cm away from the electrode assembly and aligned therewith to cause the pattern of plated metal features to be precisely located and configured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of an embodiment of an electrode assembly connected to a power supply; 
         FIGS. 2-4  schematically illustrate a noncontact method of forming a metal film on a conductive surface of a substrate according to the present invention; 
         FIG. 5  shows a top plan view of an additional pattern of the positive electrodes and the negative electrodes in the electrode assembly; 
         FIGS. 6 and 7  show side views of a pattern of the positive electrodes and the negative electrodes that is used to form bond pads on the conductive surface of the substrate; and 
         FIG. 8  is a top plan view of a pattern of the positive electrodes and the negative electrodes that is used to form bond pads on the conductive surface of the substrate. 
     
    
    
     DETAILED DESCRIPTION 
     A metal film is deposited on a conductive surface of a substrate without electrical contact between the conductive surface and electrodes of an electrode assembly. As such, the metal film is selectively deposited on the conductive surface of the substrate in the form of discrete metal features by noncontact electrochemical deposition. The metal features may be deposited on the conductive surface of the substrate when a fringe electric field, which is generated by applying a voltage across a plurality of positive electrodes and negative electrodes that are connected in series, passes through the conductive surface of the substrate. Conductive polymers or conductive salts may also be deposited on the conductive surface of the substrate rather than the metal film. As shown in  FIG. 1  positive electrodes  2  and negative electrodes  4  are adjacent to one another and are separated by an interposed insulating material  6 . The dimensions of the positive electrodes  2 , the negative electrodes  4 , and the insulating material  6  are exaggerated for clarity. In addition, only one positive electrode  2 , one insulating material  6 , and one negative electrode  4  are labeled in  FIG. 1  for the sake of clarity. However, it is understood that the positive electrodes  2  and the negative electrodes  4  alternate, with the insulating material  6  separating them. The positive electrodes  2 , the negative electrodes  4 , and the insulating material  6  form an electrode assembly  8 . Since the positive electrodes  2  and negative electrodes  4  are connected in series and are alternated in position, they provide an alternating polarity when the voltage is applied, which, in turn, creates the fringe electric field. As described in detail below, when the voltage is applied, a pattern of the metal film deposited on conductive, negatively charged cathodic portions of the substrate surface corresponds to a pattern of metal features located, sized and configured in correspondence to the location, size and shape of the positive electrodes  2  to selectively form metal features on the substrate. As noted above and described further below, the polarity of positive electrodes  2  and negative electrodes  4  may alternate cyclically if an AC power supply is employed to supply a voltage to the electrode assembly  8 . However, for simplicity in the initial description of the invention, electrode polarity is described in a fixed manner with the understanding that a DC power supply is employed. 
     The substrate may be a semiconductor substrate having at least one conductive surface. The semiconductor substrate may be a semiconductor wafer or other bulk substrate that includes a layer of semiconductor material thereon. The term “bulk substrate” as used herein includes not only silicon wafers, but also silicon on insulator (“SOI”) substrates, silicon on sapphire (“SOS”) substrates, epitaxial layers of silicon on a base semiconductor foundation, and other semiconductor materials, such as silicon-germanium, germanium, ruby, quartz, sapphire, gallium arsenide, and indium phosphide. The conductive surface of the semiconductor substrate may be a seed layer, such as a metal or a conductive metal oxide layer. The seed layer may be a thin layer of the metal that is ultimately to be plated or may be formed from a different metal. The seed layer may be blanket deposited on the semiconductor substrate by conventional techniques, such as by CVD, PVD, ALD, or electroless deposition. 
     The positive electrodes  2  and the negative electrodes  4  may be formed from an inert, electrical conductive material, such as carbon (graphite or high purity graphite) or a metal inert to the electrochemistry used in the process, such as gold, platinum, or another noble metal. As known in the art, positive electrodes  2  and negative electrodes  4  may be formed in different sizes and shapes and with varying spacing therebetween. Since the pattern of the metal film that is ultimately to be deposited on the conductive surface of the substrate depends on the pattern of the electrodes in the electrode assembly  8 , the sizes and the shapes of the positive electrodes  2  may be selected based on the desired pattern of the metal film. Each of the positive electrodes  2  may be a different size or shape or the same size or shape, and the negative electrodes  4  may be cooperatively sized and shaped to provide substantially constant lateral spacing between positive and negative electrodes for substantially uniform fringe electric field intensity. 
     To prevent shorting between adjacent, oppositely charged electrodes, the insulating material  6  may be a dielectric material that is conventionally used in semiconductor devices, such as borophosphosilicate glass (“BPSG”). The insulating material  6  may also be a synthetic polymer, such as a polyimide, polyketone, polyetherketone, polysulfone, polycarbonate, polystyrene, nylon, polyvinylchloride, polypropylene, polyethersulfone, polyethylene terephthalate, fluoroethylene propylene copolymer, cellulose, triacetate, silicone, or rubber. A thin layer of the insulating material  6  may be used to separate the positive electrodes  2  and the negative electrodes  4 , the desirable thickness depending upon spacing or pitch between the electrodes  2 ,  4  and the dielectric constant. For the sake of example only, the insulating material  6  may be a dielectric epoxy that is applied to a pattern of positive electrodes  2  and the negative electrodes  4 , such as by dipping the electrode pattern in the epoxy and etching back the epoxy to expose the electrodes  2 ,  4 . Alternatively, positive electrodes  2  and negative electrodes  4  may be formed by selectively masking and etching a metal layer on a surface of a dielectric substrate such as, for example, a polyimide or a glass. 
     The positive electrodes  2  and the negative electrodes  4  may be connected in series to form the desired pattern of the electrode assembly  8 . As previously mentioned, this pattern determines the pattern of the metal film that is ultimately to be deposited on the conductive surface of a substrate  14 . For instance, the positive electrodes  2  and the negative electrodes  4  may be configured as a pattern of straight, alternating bars, as shown in  FIGS. 2-4 , to produce a corresponding or identical pattern of “stripes” of metal film  26  on the conductive surface of substrate  14 . However, additional patterns of the positive electrodes  2  and the negative electrodes  4  may be contemplated to form other patterns of the metal film  26  on the conductive surface of substrate  14 . The dimensions and spacing between each of the adjacent positive electrodes  2  and the negative electrodes  4  may be adjusted based on the desired pattern of the metal film  26  that is ultimately to be deposited on the conductive surface of substrate  14 . 
       FIG. 5  illustrates an example of an additional pattern in which the positive electrodes  2  and the negative electrodes  4  may be connected. The insulating material  6  may separate the positive electrodes  2  from the negative electrodes  4 . The positive electrodes  2  may form a conductive trace shape  28  that corresponds to a metal feature in the form of a conductive trace to be formed on the conductive surface of the substrate  14 . 
       FIGS. 6-8  show additional examples of patterns in which the positive electrodes  2  and the negative electrodes  4  may be connected to form bond pads on the conductive surface of the substrate  14 . The positive electrodes  2  and the negative electrodes  4  may be formed on a surface of a dielectric layer  30 , such as a layer of KRYLON® or KAPTON®. As shown in  FIGS. 6 and 8 , the positive electrodes  2  and negative electrodes  4  may be formed as by selective etching of a conductive layer laminated to a surface of the dielectric layer  30 . The positive electrodes are connected to the voltage source by a wiring line extending over dielectric layer  30 , while surrounding negative electrode  4  may be merely connected at the edge thereof. The positive electrodes  2  and the negative electrodes  4  may be separated from one another by material of the dielectric layer  30  (see  FIG. 7 ), by an air space  32  (see  FIG. 6 ), or by a combination thereof. 
     An electroplating system is also disclosed (see  FIG. 1 ). The electroplating system may include the electrode assembly  8  and a power supply  10  selectively operably coupled to the electrode assembly  8 . The positive electrodes  2  and the negative electrodes  4  of electrode assembly  8  may be connected to the power supply  10  through power lines  12 . The power supply  10  provides the operating voltage and current to the electrode assembly  8  so that the positive electrodes  2  have a positive potential relative to the negative electrodes  4 . The power supply  10  may be a conventional AC power supply or a conventional DC power supply that supplies a voltage ranging from approximately 0.1 volts to approximately 150 volts to the electrode assembly  8 . For instance, the voltage supplied to the electrode assembly  8  may range from approximately 0.1 volts to approximately 10 volts.  FIG. 1  illustrates a DC connection in which a conventional DC power supply is connected to the electrode assembly  8 . It should be noted that in the instance where an AC power supply is employed, the designation of an electrode as a positive or a negative electrode will vary with each polarity reversal of the cycling power supply. 
     The conductive surface of substrate  14  may be positioned in close proximity to the electrode assembly  8 , as shown in  FIG. 2 . While  FIG. 2  shows the electrode assembly  8  positioned over the conductive surface of substrate  14 , additional configurations may be contemplated as long as the electrode assembly  8  and the conductive surface of substrate  14  are in close proximity. The substrate  14  may be supported on a holding mechanism, such as a chuck or platen  20 , with its conductive surface facing upwardly. A temperature at which the substrate  14  is maintained may depend on the metal of the metal film  26  that is to be deposited on the substrate  14 . For the sake of example only, the substrate  14  may be maintained at a temperature of approximately 25° C. For the sake of clarity and convenience, the power supply  10  and the power lines  12  are not shown in  FIG. 2 . The electrode assembly  8  may be positioned over the conductive surface of substrate  14  through electrode support  16 , which may include alignment features for cooperative engagement with alignment features on the chuck or platen  20  to provide precise alignment in the X-Y (horizontal) plane and precise rotational alignment about the Z (vertical axis) perpendicular to the X-Y plane with respect to substrate  14  and, for example, a plurality of semiconductor die locations thereon. The distance at which the electrode assembly  8  is desirably positioned from the conductive surface of the substrate  14  may depend on the intensity of the fringe electric field generated and on types and concentrations of electrolytes used in an electrolyte solution  18 . This distance may be adjusted to increase or reduce the current densities under the positive electrodes  2  and the negative electrodes  4 , which affects a plating rate of the metal film  26 . Since the various positive and negative electrodes may be of different sizes and shapes, lateral distances between peripheries of adjacent positive electrodes  2  and negative electrodes  4  as well as transverse, or vertical, distances of individual positive electrodes  2  and the negative electrodes  4  away from the conductive surface of substrate  14  may also vary. The distance between the positive electrodes  2  and negative electrodes  4  of electrode assembly  8  and the conductive surface of substrate  14  may range from approximately 0.1 mm to approximately 1 cm, such as from approximately 2 mm to approximately 5 mm. By positioning the electrodes of electrode assembly  8  closer to the surface of the conductive surface of substrate  14 , the current density under the electrodes may be increased, which increases the plating rate of the metal film  26  under the positive electrodes  2 . Conversely, by positioning the electrodes of electrode assembly  8  further from the conductive surface of substrate  14 , the current density under the positive electrodes  2  may be decreased to decrease the plating rate of the metal film  26 . 
     The conductive surface of substrate  14  may be contacted with the electrolyte solution  18  that includes metal ions of the metal film  26  to be deposited. These metal ions may electrodeposit on the conductive surface of substrate  14  under positive electrodes  2  when the electric field is applied. The metal ions may dissociate from a metal salt that is soluble in a liquid medium of the electrolyte solution  18 . The liquid medium may be aqueous, may include organic solvents, or may include a mixture of water and organic solvents. The metal ions may be nickel ions, copper ions, cobalt ions, platinum ions, aluminum ions, silver ions, gold ions, chromium ions, iron ions, zinc ions, cadmium ions, palladium ions, tin ions, or bismuth ions. As such, the electrolyte solution  18  may include, but is not limited to, an aqueous solution of nickel sulfate, nickel chloride, copper sulfate, cobalt chloride, or Pt(NH 3 ) 2 Cl 2 . The electrolyte solution  18  may optionally include acids, surfactants, complexing agents, accelerator additives, suppressor additives, and other conventional ingredients. 
     To enable the electrolyte solution  18  to flow between the electrode assembly  8  and the conductive surface of substrate  14 , the electrode assembly  8  does not directly contact the conductive surface of substrate  14 . The electrolyte solution  18  may be applied to the conductive surface of substrate  14  by spraying. Alternatively, the conductive surface of substrate  14  may be immersed in the electrolyte solution  18 , such as by immersing the substrate  14  on chuck the chuck or platen  20  in an immersion bath that contains the electrolyte solution  18 . When the voltage is applied to the electrode assembly  8 , a fringe electric field  21  is generated by the alternating polarities of the positive electrodes  2  and the negative electrodes  4 , as shown in  FIG. 3 . For the sake of clarity, one fringe electric field  21  is illustrated in  FIG. 3 . However, it is understood that multiple fringe electric fields  21  may be present between the alternating positive electrodes  2  and the negative electrodes  4 . The fringe electric field  21  may desirably be of sufficient strength to expose the conductive surface of substrate  14  to the electric field. The voltage may be applied through the electrode assembly  8  for an amount of time sufficient to deposit a desired thickness of the metal film  26  on the conductive surface of substrate  14 . The metal film  26  may have a thickness ranging from approximately 100 Å to approximately 5 μm. The fringe electric field  21  may pass through the conductive surface of substrate  14 , creating localized, anodic portions  22  and cathodic portions  24  on the conductive surface of substrate  14 . For instance, a portion of the conductive surface of the substrate  14  beneath the positive electrode  2  acts as a cathode (cathodic portion  24 ) and a portion of the conductive surface of the substrate  14  beneath the negative electrode  4  acts as an anode (anodic portion  22 ). The cathodic portion  24  of the conductive surface of substrate  14  has a negative charge while the anodic portion  22  has a positive charge. For the sake of clarity and convenience, one cathodic portion  24  and one anodic portion  22  are illustrated in  FIG. 3 . However, it is understood that cathodic portions  24  are formed beneath the plurality of positive electrodes  2  and anodic portions  22  are formed beneath the plurality of negative electrodes  4 . 
     The metal ions in the electrolyte solution  18  are attracted to the portions of the conductive surface of substrate  14  having an opposite charge and, therefore, may deposit on the conductive surface of substrate  14  to form the metal film  26 . Since the metal ions in the electrolytic solution  18  have a positive charge, they are attracted to, and may deposit on, the cathodic portions  24  of the conductive surface of substrate  14 . As shown in  FIG. 4 , the metal film  26  may be deposited as discrete metal features in localized areas of the substrate  14  that are positioned below the positive electrodes  2 . Therefore, the positive electrodes  2  may be positioned over portions of the conductive surface of substrate  14  that are to be plated with the metal features while the negative electrodes  4  may be positioned over portions of the conductive surface of substrate  14  that are to remain unplated. Since the metal ions are deposited beneath the positive electrodes  2 , the metal features may be selectively plated on the desired portions of the conductive surface of substrate  14  by adjusting the sizes and configurations of positive electrodes  2  and their respective positions over the conductive surface of substrate  14 . 
     The metal features formed by the noncontact electroplating method of the present invention may comprise a film of nickel, copper, cobalt, platinum, aluminum, silver, gold, chromium, iron, zinc, cadmium, palladium, platinum, tin, or bismuth. Metal alloys, such as Sn/Ni, NiWP, CoWP, or Cu/Zn, may also be formed. In one embodiment, the metal film  26  is a film of nickel, copper, cobalt, or platinum. Of course, multiple metal layers may be deposited in superimposition by using the same pattern for electrode assembly  18  with different electrolyte solutions  18  in different reservoirs. 
     By selectively depositing the metal features, the conductive surface of substrate  14  may not include metal film portions extraneous to metal features thereon, which would require subsequent removal. In addition, since the positive electrodes  2  and the negative electrodes  4  are not attached to the conductive surface of substrate  14  by mechanical electrical contacts, potential defects in the electrode attachments, a concern with prior art techniques, cannot occur. Control of electroplating the metal features is also enhanced compared to conventional electroless plating techniques. Furthermore, since the fringe electric field  21  is located adjacent to the portion of the conductive surface of substrate  14  that is to be plated, the metal features may be uniformly and consistently deposited. The noncontact electroplating method may also enable the selective deposition of the metal features without using a mask. Since the metal features are deposited selectively, a mask is not required to cover portions of the conductive surface of substrate  14  that are to remain unplated. Instead, after plating is completed, unplated portions of the seed layer comprising the conductive surface may be easily removed by a selective solvent. The solvent may be chosen by one of ordinary skill in the art based on the materials used in the seed layer and in the substrate  14 . 
     As described above, in one embodiment, the electrode assembly  8  is attached to a DC power supply to selectively deposit the metal features on the conductive surface of substrate  14 . In another embodiment, the metal features are deposited over areas of the conductive surface of substrate  14  proximate and beneath each electrode  2  and  4  by attaching the electrodes  2  and  4  of electrode assembly  8  to an AC power supply. In this situation, wherein the power supply  10  comprises an AC power supply operably coupled to electrodes  2  and  4  in the same manner as the DC power supply previously described with respect to  FIG. 1 , the polarity of electrodes  2  and  4  varies and metal features may be deposited under both electrodes  2  and electrodes  4  because the polarities of the electrodes reverse with each cycle of the AC power supply. For instance, during one cycle of the AC power supply, the electrodes  2  may exhibit a positive polarity while the electrodes  4  may exhibit a negative polarity. However, during a second, reverse AC power cycle, the polarities of the electrodes are reversed. Due to the cycling of the AC power supply, portions of the conductive surface of substrate  14  under the electrodes  2  or under the electrodes  4  may be negatively charged and comprise a cathodic portion  24 . In other words, at different points in time, portions of the conductive surface of substrate  14  beneath the electrodes  2  or beneath the electrodes  4  have a negative charge upon which the metal ions from electrolyte solution  18  may deposit to form the metal features. Accordingly, an AC power supply may be used to plate metal features in closer proximity (smaller spacing or pitch) on the conductive surface of substrate  14  that is positioned beneath the electrode assembly  8  than if a DC power supply is employed. Using the present invention may enable the metal features to be deposited more uniformly over larger portions of the conductive surface of substrate  14  than with prior art techniques employing electrode edge connections at a wafer periphery, which result in a drop in potential toward the wafer center. The noncontact electroplating process of the present invention may be used to form metal features on the conductive surface of substrate  14  including, but not limited to, bond pads, traces and damascene structures. Electroplating such metal features is one of many steps in fabricating the integrated circuits. As such, the electroplating process of the present invention may be used to form intermediate semiconductor device structures. By using the noncontact electroplating process of the present invention, the bond pads may be selectively formed on the conductive surface of substrate  14  without undesirably plating the metal film  26  on other portions of the substrate  14 . The noncontact electroplating process may also be used to form metal interconnects of the damascene structures. By selectively plating the metal interconnects, subsequent polishing steps to remove extraneous film may be reduced or eliminated. The fabrication of the damascene structures is known in the art and, therefore, is not discussed in detail herein. 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.