Patent Publication Number: US-2009218231-A1

Title: Plating apparatus

Description:
This application is a divisional of U.S. application Ser. No. 10/485,350, filed Aug. 19, 2004, which is a national stage application of International application No. PCT/JP03/09144, filed Jul. 18, 2003. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a plating apparatus for carrying out plating of a surface of a plating workpiece to be plated, such as a substrate, and more particularly to a plating apparatus for forming a plated film in fine interconnect trenches or holes, via holes, through-holes, or resist openings formed in a surface of a semiconductor wafer or the like, or for forming a bump (protruding electrode), which provides electrical connection with an electrode of a package or the like, on a surface of a semiconductor wafer. 
     BACKGROUND ART 
     In TAB (Tape Automated Bonding) or FC (Flip Chip), for example, it has widely been practiced to form protruding connecting electrodes (bumps) of gold, copper, solder, lead-free solder, or nickel, or a multi-layer laminate of these metals at predetermined portions (electrodes) on a surface of a semiconductor chip having interconnects formed therein, and to electrically connect the interconnects via the bumps with electrodes of a package or with TAB electrodes. Methods of forming bumps include various methods, such as electroplating, vapor deposition, printing, and ball bumping. With a recent increase in the number of I/O in a semiconductor chip and a trend toward finer pitches, electroplating has more frequently been employed because it can cope with fine processing and has relatively stable performance. 
     With an electroplating method, a metal film (plated film) having a high purity can readily be obtained. Further, an electroplating method has a relatively high deposition rate of a metal film, and control of thickness of the metal film can be performed relatively easily. 
       FIG. 37  shows an example of a conventional plating apparatus which employs a so-called face-down method. The plating apparatus has an upwardly opened plating tank  12  for holding a plating solution  10  therein and a vertically movable substrate holder  14  for detachably holding a substrate W in a state such that a front face (surface to be plated) of the substrate W faces downward (face-down). An anode  16  is disposed horizontally at a bottom of the plating tank  12 . Overflow tanks  18  are provided around an upper portion of the plating tank  12 . Further, a plating solution supply nozzle  20  is connected to the bottom of the plating tank  12 . 
     In operation, a substrate W held horizontally by the substrate holder  14  is located at a position such as to close an opening at an upper end of the plating tank  12 . In this state, the plating solution  10  is supplied from the plating solution supply nozzle  20  into the plating solution tank  12  and allowed to overflow the upper portion of the plating tank  12 , thereby bringing the plating solution  10  into contact with a surface of the substrate W held by the substrate holder  14 . Simultaneously, the anode  16  is connected via a conductor  22   a  to an anode of a plating power supply  24 , and the substrate W is connected via a conductor  22   b  to a cathode of the plating power supply  24 . Thus, due to a potential difference between the substrate W and the anode  16 , metal ions in the plating solution  10  receive electrons from the surface of the substrate W, so that metal is deposited on the surface of the substrate W so as to form a metal film. 
     According to the plating apparatus, uniformity of the thickness of the metal film formed on the surface of the substrate W can be adjusted to a certain extent by adjusting the size of the anode  16 , an interpolar distance and potential difference between the anode  16  and the substrate W, a supply rate of the plating solution  10  supplied from the plating solution supply nozzle  20 , and the like. 
       FIG. 38  shows an example of a conventional plating apparatus which employs a so-called dipping method. The plating apparatus has a plating tank  12   a  for holding a plating solution  12   a  therein and a vertically movable substrate holder  14   a  for detachably holding a substrate W in a state such that a front face (surface to be plated) is exposed while a peripheral portion of the substrate W is water-tightly sealed. An anode  16   a  is held by an anode holder  26  and disposed vertically within the plating tank  12 . Further, a regulation plate  28  made of a dielectric material having a central hole  28   a  is disposed in the plating tank  12  so as to be positioned between the anode  16   a  and the substrate W when the substrate W held by the substrate holder  14   a  is disposed at a position facing the anode  16   a.    
     In operation, the anode  16   a , the substrate W, and the regulation plate  28  are immersed in the plating solution in the plating tank  12   a . Simultaneously, the anode  16   a  is connected via a conductor  22   a  to an anode of a plating power supply  24 , and the substrate W is connected via a conductor  22   b  to a cathode of the plating power supply  24 . Accordingly, metal is deposited onto the surface of the substrate W so as to form a metal film in the same manner as described above. 
     According to the plating apparatus, distribution of thickness of the metal film formed on the surface of the substrate W can be adjusted to a certain extent by disposing the regulation plate  28  having the central hole  28   a  between the anode  16   a  and the substrate W disposed at a position facing the anode  16   a , and adjusting a potential distribution on the plating bath  12   a  with the regulation plate  28 . 
       FIG. 39  shows another example of a conventional plating apparatus which employs a so-called dipping method. The plating apparatus differs from the apparatus shown in  FIG. 38  in that a ring-shaped dummy cathode (dummy electrode)  30  is provided instead of a regulation plate, that a substrate W is held by a substrate holder  14   a  in a state such that the dummy cathode  30  is disposed around the substrate W, and that the dummy cathode  30  is connected to a cathode of a plating power supply  24  during plating. 
     According to the plating apparatus, uniformity of thickness of a plated film formed on the surface of the substrate W can be improved by adjusting an electric potential of the dummy cathode  30 . 
     On the other hand, for example, when a metal film (plated film) for interconnects or bumps is formed on a surface of a semiconductor substrate (wafer), the metal film formed is required to be uniform in surface profile and in film thickness over the entire surface of the substrate. There are increasing demands for a high degree of uniformity in recent high-density packaging technologies such as SOC and WL-CSP. However, with the above conventional plating apparatuses, it is quite difficult to form a metal film that meets a high degree of uniformity requirement. 
     Specifically, when a substrate is plated by the plating apparatus shown in  FIG. 37 , a metal film is formed under a strong influence of a flow of the plating solution. If the plating solution flows fast, as shown in  FIG. 40A , the thickness of the metal film P tends to be thicker in a central portion of the substrate W, to which metal ions are sufficiently supplied, than in a peripheral portion of the substrate W. If the flow of the plating the solution is made considerably weak in order to prevent the above phenomenon, as shown in  FIG. 40B , the thickness of the metal film P tends to be thicker in a peripheral portion of the substrate W than in a central portion. When a substrate W is plated by the plating apparatus shown in  FIG. 38 , a potential distribution can be improved by the regulation plate having the central hole, so that the uniformity of the film thickness distribution of a metal film can be improved to a certain extent over the entire surface of the substrate. However, as shown in  FIG. 40C , the metal film P tends to have an undulate thickness distribution, in which the film thickness is thicker in a central portion and a peripheral portion of the substrate W. Further, when a substrate is plated by the plating apparatus shown in  FIG. 39 , it is difficult to adjust a voltage applied to the dummy electrode (dummy cathode). In addition, it becomes necessary to remove a metal film attached to a surface of the dummy electrode, and the removal necessitates a troublesome operation. 
     In the conventional plating apparatuses, there is a general tendency that due to a surface potential distribution produced over a surface of a substrate, the film thickness of a plated film is larger in a peripheral portion of the substrate, which serves as an electrically receiving portion, causing a U-shaped film thickness distribution over the substrate surface (see  FIG. 40B ). This is one of the main factors that impair the uniformity of film thickness. In order to suppress this phenomenon, a regulation plate or a dummy electrode is employed in a method of regulating supply of metal ions to a surface of a substrate, i.e. regulating a flow of a plating solution, and a method of controlling or regulating a potential distribution on a surface of a substrate and an electric field in a plating tank. 
     The regulating method of a flow of a plating solution and the regulating method using a regulation plate are intended to concentrate metal ions or an electric field to a central portion of a substrate to raise a plated film at the central portion of the substrate, thereby adjusting a film thickness distribution of the plated film over the entire substrate surface so as to be a W-shaped distribution and minimizing a film thickness variation from an average film thickness (see  FIG. 40C ). Accordingly, the uniformity of the film thickness is greatly influenced by regulation of the flow of the plating solution and by selection and fine control of the position of the regulation plate and the size of the central hole. Thus, the uniformity of the film thickness is greatly influenced by the degree of adjustment (tuning). 
     On the other hand, the method using a dummy electrode is intended to broaden a range of a potential distribution from a substrate surface to a region including the dummy electrode around the substrate, thereby shifting the raised portion of the plated film in the electrically receiving portion to the dummy electrode and obtaining an extremely uniform film thickness on the substrate surface. As an equivalent method to the method employing a dummy electrode, there has also been known a method which uses a pattern in a peripheral portion of a substrate as a “discarded chip” so as to serve as a dummy electrode. In such methods that employ a dummy electrode, the uniformity of the film thickness is influenced by adjustment of a voltage. Further, it is necessary to periodically remove a metal film (plated film) attached to the dummy electrode, which necessitates a troublesome operation. When a pattern in a peripheral portion of a substrate is used as a “discarded chip” so as to serve as a dummy electrode, the number of effective chips per substrate is inevitably reduced to thereby cause a lowered productivity. 
     All of the above-described methods eventually adjust a film thickness distribution to obtain a uniform film thickness distribution. Thus, none of the above-described methods are intended to positively control or regulate an electric field in a plating tank, which is produced between an anode and a plating workpiece as a cathode, so as to control and improve a potential distribution on a surface of the plating workpiece, thereby equalizing and improving the film thickness distribution of the plated film which would otherwise become a U-shaped distribution. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above drawback. It is, therefore, an object of the present invention to provide a plating apparatus which can form a metal film (plated film) having a uniform thickness over an entire plating workpiece with a relatively simple arrangement and without needs for a complicated operation and setting. 
     In order to achieve the above object, the present invention provides a plating apparatus characterized by comprising a plating tank for holding a plating solution; an anode disposed so as to be immersed in the plating solution in the plating tank; a regulation plate disposed between the anode and a plating workpiece disposed so as to face the anode; and a plating power supply for supply a current between the anode and the plating workpiece to carry out plating, wherein the regulation plate is disposed so as to separate the plating solution held in the plating tank into a plating solution on the anode side and a plating solution on the plating workpiece side, and a through-hole group having a large number of through-holes is formed in the regulation plate. 
     According to the present invention, an electric field leaks through a large number of through-holes formed in the regulation plate disposed in the plating tank, and the leaked electric field spreads uniformly. Accordingly, a potential distribution can be made more uniform over an entire surface of the plating workpiece, and a within wafer uniformity of a metal film formed on the surface of the plating workpiece can be enhanced. Further, the plating solution is prevented from passing through a large number of through-holes formed in the regulation plate provided in the plating tank. Accordingly, a non-uniform metal film thickness is prevented from being formed on the surface of the plating workpiece due to influence of a flow of the plating solution. 
     According to a preferred aspect of the present invention, the through-hole group is formed by a plurality of slit-like elongated holes extending linearly in one direction or extending in an arc. The use of slit-like elongated holes as the through-holes can promote leakage of electric field while preventing the plating solution from passing through the through-holes. For example, the widths of the elongated holes are set to be about 0.5 to 20 mm, preferably about 1 to 15 mm. The lengths of the elongated holes are determined depending upon the shape of the plating workpiece. 
     According to a preferred aspect of the present invention, the through-hole group is formed by a plurality of cross holes extending crosswise in vertical and horizontal directions. 
     According to a preferred aspect of the present invention, the through-hole group is formed by a combination of a plurality of fine holes, a plurality of holes having different diameters, and slit-like elongated holes. The use of a combination of a plurality of fine holes, a plurality of holes having different diameters, and slit-like elongated holes as the through-hole group can increase the productivity. For example, the diameters of the fine holes or small holes (peripheral holes) are set to be about 1 to 20 mm, preferably about 2 to 10 mm. For example, the diameters of large holes (central holes) are set to be about 50 to 300 mm, preferably about 30 to 100 mm. 
     It is desirable that the through-hole group be formed in the regulation plate substantially over an entire area facing the plating workpiece, and formed in an area substantially similar to a shape of the plating workpiece. With such a through-hole group, it is possible to form a metal film having a good film thickness uniformity in all directions on the plating workpiece. 
     Preferably, the plating apparatus comprises an agitating mechanism provided between the plating workpiece and the regulation plate for stirring the plating solution held in the plating tank. By agitating the plating solution between the plating workpiece and the regulation plate by the agitating mechanism during plating, sufficient ions can be supplied more uniformly to the plating workpiece. Therefore, a metal film having a more uniform thickness can be formed more rapidly. 
     Preferably, the agitating mechanism should comprise a paddle-type agitating mechanism having a paddle which reciprocates parallel to the plating workpiece. By reciprocating a paddle parallel to the plating workpiece during plating to agitate the plating solution by the paddle, the directionality of the flow of the plating solution can be eliminated, and simultaneously sufficient ions can be supplied more uniformly to the surface of the plating workpiece. 
     According to a preferred aspect of the present invention, the anode and the regulation plate are provided in a vertical direction. This arrangement provides a plating apparatus with a small installation space and having excellent maintainability. 
     The present invention also provides another plating apparatus characterized by comprising a plating tank for holding a plating solution; an anode disposed so as to be immersed in the plating solution in the plating tank; a regulation plate disposed between the anode and a plating workpiece disposed so as to face the anode; and a plating power supply for supply a current between the anode and the plating workpiece to carry out plating, wherein the regulation plate is disposed so as to separate the plating solution held in the plating tank into a plating solution on the anode side and a plating solution on the plating workpiece side, and a plating solution passage is formed in the regulation plate for allowing an electric field to uniformly pass therethrough and allowing the plating solution to pass therethrough. 
     By thus allowing the electric field produced between the anode and the plating workpiece in the plating tank to pass uniformly through the plating solution passage without leaking out of the plating solution passage, distortion or deviation of the electric field can be adjusted and corrected so as to equalize a potential distribution over an entire surface of the plating workpiece, thereby enhancing a within wafer uniformity of a metal film formed on the plating workpiece. 
     The length of the plating solution passage is properly determined depending upon the shape of the plating tank, the distance between the anode and the plating workpiece, and the like. However, the length is generally 10 to 90 mm, preferably 20 to 75 mm, more preferably 30 to 60 mm. 
     Preferably, the plating solution passage is defined by an inner circumferential surface of a cylindrical member or a rectangular block. This arrangement can simplify the structure. 
     It is desirable that a large number of through-holes having a size such as to prevent leakage of an electric field be formed in a circumferential wall of the cylindrical member. With this arrangement, the plating solution is allowed to pass through the through-holes formed in the circumferential wall of the cylindrical member while preventing leakage of the electric field. Accordingly, the concentration of the plating solution is prevented from being different between the inside and outside of the cylindrical member. With respect to the shape of the through-holes, for example, fine holes, slit-like elongated holes, cross holes extending vertically and horizontally, and a combination thereof may be exemplified. 
     According to a preferred aspect of the present invention, the plating apparatus comprises an agitating mechanism provided in at least one of a space between the plating workpiece and the regulation plate and a space between the anode and the regulation plate for agitating the plating solution held in the plating tank. By agitating the plating solution during plating, the concentration of the plating solution containing metal ions and various additives can be made uniform in the plating tank, and the plating solution having a uniform concentration can be supplied to the plating workpiece. Accordingly, a metal film having a more uniform thickness can be formed more rapidly. 
     The agitating mechanism is preferably a paddle-type agitating mechanism having a paddle which reciprocates parallel to the plating workpiece. 
     The agitating mechanism may comprise a plating solution injection type agitating mechanism having a plurality of plating solution injection nozzles for ejecting the plating solution toward the plating workpiece. By injecting the plating solution from the plurality of plating solution injection nozzles toward the plating workpiece, the plating solution in the plating tank can be agitated so as to uniformize the plating solution concentration and, simultaneously, to sufficiently supply components of the plating solution to the plating workpiece. Thus, a metal film having a more uniform thickness can be formed more rapidly. 
     The plating solution passage may be formed in the regulation plate integrally with the regulation plate. A thick regulation plate may be used, and a through-hole may be formed in the regulation plate so as to serve as a plating solution passage. 
     The present invention provides yet another plating apparatus comprising a plating tank for holding a plating solution; an anode disposed so as to be immersed in the plating solution in the plating tank; a regulation plate disposed between the anode and a plating workpiece disposed so as to face the anode for separating the plating solution held in the plating tank into a plating solution on the anode side and a plating solution on the plating workpiece side, the regulation plate having a plating solution passage for allowing an electric field to uniformly pass therethrough and allowing the plating solution to pass therethrough; a plating power supply for supply a current between the anode and the plating workpiece to carry out plating; and an electric field adjustment ring disposed at an end of the plating solution passage on the plating workpiece side for adjusting an electric field at a peripheral portion of the plating workpiece. 
     By adjusting an electric field at a peripheral portion of the plating workpiece by the electric field adjustment ring, an electric field produced between the anode and the plating workpiece can be uniformized over an entire surface of the plating workpiece, including an edge portion of the plating workpiece, which serves as an electrically receiving portion. Therefore, a within wafer uniformity of a metal film formed on the plating workpiece can be further enhanced. 
     The shape of the electric field adjustment ring may be properly determined depending upon the shape of the plating tank, the shape of the plating workpiece, the distance between the anode and the plating workpiece, and the like. The width of the ring is generally set to be in a range of 1 to 20 mm, preferably 3 to 17 mm, more preferably 5 to 15 mm. 
     A gap between the electric field adjustment ring and the plating workpiece is generally set to be in a range of 0.5 to 30 mm, preferably 1 to 15 mm, more preferably 1.5 to 6 mm. 
     According to a preferred aspect of the present invention, the plating solution passage is defined by an inner circumferential surface of a cylindrical member, and the electric field adjustment ring is connected to an end of the cylindrical member on the plating workpiece side. 
     Alternatively, the plating solution passage may be defined by an inner circumferential surface of a cylindrical member, and the electric field adjustment ring may be disposed at an end of the cylindrical member on the plating workpiece side so as to be separated from the cylindrical member. With such a separated plating solution passage, the cylindrical member and the electric field adjustment ring can be separated so as to offer a broader choice. 
     Alternatively, the plating solution passage may be defined by an inner circumferential surface of a cylindrical member, and the electric field adjustment ring may be formed on an end surface of the plating workpiece side. With this arrangement, the number of parts can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall layout of a plating facility having a plating apparatus according to an embodiment of the present invention; 
         FIG. 2  is a schematic view of a transfer robot provided in a plating space of a plating processing apparatus shown in  FIG. 1 ; 
         FIG. 3  is a schematic cross-sectional view of a plating apparatus provided in the plating processing apparatus shown in  FIG. 1 ; 
         FIG. 4  is a schematic perspective view of a main portion of the plating apparatus shown in  FIG. 3 ; 
         FIG. 5  is a plan view of a regulation plate provided in the plating apparatus shown in  FIG. 3 ; 
         FIG. 6  is a schematic diagram illustrating a state of a metal film (plated film) formed by the plating apparatus shown in  FIG. 3 ; 
         FIGS. 7A through 7E  are cross-sectional diagrams sequentially illustrating a process of forming a bump (protruding electrode) on a substrate; 
         FIG. 8  is a plan view showing another example of a regulation plate; 
         FIG. 9  is a plan view showing still another example of a regulation plate; 
         FIG. 10  is a plan view showing yet another example of a regulation plate; 
         FIG. 11  is a plan view showing yet another example of a regulation plate; 
         FIG. 12  is a plan view showing yet another example of a regulation plate; 
         FIG. 13  is a plan view showing yet another example of a regulation plate; 
         FIG. 14  is a plan view showing yet another example of a regulation plate; 
         FIG. 15  is a plan view showing yet another example of a regulation plate; 
         FIG. 16  is a plan view showing yet another example of a regulation plate; 
         FIG. 17  is a plan view showing yet another example of a regulation plate; 
         FIG. 18  is a plan view showing yet another example of a regulation plate; 
         FIG. 19  is a plan view showing yet another example of a regulation plate; 
         FIG. 20  is a schematic cross-sectional view showing a plating apparatus according to another embodiment of the present invention; 
         FIG. 21A  is a perspective view showing a regulation plate and a cylindrical member provided in the plating apparatus shown in  FIG. 20 ; 
         FIG. 21B  is a front view of  FIG. 21A ; 
         FIG. 22  is a schematic diagram illustrating a state of a metal film (plated film) formed by the plating apparatus shown in  FIG. 20 ; 
         FIG. 23  is a schematic cross-sectional view showing a plating apparatus according to still another embodiment of the present invention; 
         FIG. 24A  is a perspective view showing another example of a regulation plate and a cylindrical member; 
         FIG. 24B  is a front view of  FIG. 24A ; 
         FIG. 25A  is a perspective view showing still another example of a regulation plate and a cylindrical member; 
         FIG. 25B  is a front view of  FIG. 25A ; 
         FIG. 26A  is a perspective view showing yet another example of a regulation plate and a cylindrical member; 
         FIG. 26B  is a front view of  FIG. 26A ; 
         FIG. 27A  is a perspective view showing yet another example of a regulation plate and a cylindrical member; 
         FIG. 27B  is a front view of  FIG. 27A ; 
         FIG. 28  is a schematic cross-sectional view showing a plating apparatus according to yet another embodiment of the present invention; 
         FIG. 29A  is a perspective view showing a regulation plate, a cylindrical member, and an electric field adjustment ring provided in the plating apparatus shown in  FIG. 28 ; 
         FIG. 29B  is a front view of  FIG. 29A ; 
         FIG. 30  is a schematic diagram illustrating a metal film (plated film) formed by the plating apparatus shown in  FIG. 28 ; 
         FIG. 31  is a schematic cross-sectional view showing a plating apparatus according to yet another embodiment of the present invention; 
         FIG. 32A  is a perspective view showing another example of a regulation plate, a cylindrical member, and an electric field adjustment ring; 
         FIG. 32B  is a front view of  FIG. 32A ; 
         FIG. 33A  is a perspective view showing still another example of a regulation plate, a cylindrical member, and an electric field adjustment ring; 
         FIG. 33B  is a front view of  FIG. 33A ; 
         FIG. 34A  is a perspective view showing yet another example of a regulation plate, a cylindrical member, and an electric field adjustment ring; 
         FIG. 34B  is a front view of  FIG. 34A ; 
         FIG. 35A  is a perspective view showing yet another example of a regulation plate, a cylindrical member, and an electric field adjustment ring; 
         FIG. 35B  is a front view of  FIG. 35A ; 
         FIG. 36  is a schematic cross-sectional view showing a plating apparatus according to yet another embodiment of the present invention; 
         FIG. 37  is a schematic cross-sectional view showing an example of a conventional plating apparatus; 
         FIG. 38  is a schematic perspective view showing another example of a conventional plating apparatus; 
         FIG. 39  is a schematic perspective view showing still another example of a conventional plating apparatus; and 
         FIGS. 40A through 40C  are schematic diagrams illustrating various states of metal films (plated films) formed by conventional plating apparatuses. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiments of the present invention will be described below with reference to the drawings. The following embodiments show examples in which a substrate such as a semiconductor wafer is used as a plating workpiece. 
       FIG. 1  shows an overall layout of a plating facility having a plating apparatus according to an embodiment of the present invention. The plating facility is designed so as to automatically perform all the plating processes including pretreatment of a substrate, plating, and post treatment of the plating, in a successive manner. The interior of an apparatus frame  110  having an armored panel attached thereto is divided by a partition plate  112  into a plating space  116  for performing a plating process of a substrate and treatments of the substrate to which a plating solution is attached, and a clean space  114  for performing other processes, i.e. processes not directly involving a plating solution. Two substrate holders  160  (see  FIG. 2 ) are arranged in parallel, and substrate attachment/detachment stages  162  to attach a substrate to and detach a substrate from each substrate holder  160  are provided as a substrate delivery section on a partition portion partitioned by the partition plate  112 , which divides the plating space  116  from the clean space  114 . Loading/unloading ports  120 , on which substrate cassettes storing substrates are mounted, are connected to the clean space  114 . Further, the apparatus frame  110  has a console panel  121  provided thereon. 
     In the clean space  114 , there are disposed at four corners an aligner  122  for aligning an orientation flat or a notch of a substrate with a predetermined direction, two cleaning/drying devices  124  for cleaning a plated substrate and rotating the substrate at a high speed to spin-dry the substrate, and a pretreatment device  126  for carrying out a pretreatment of a substrate, e.g., according to the present embodiment, a rinsing pretreatment including injecting pure water toward a front face (surface to be plated) of a substrate to thereby clean the substrate surface with pure water and, at the same time, wet the substrate surface with pure water so as to enhance a hydrophilicity of the substrate surface. Further, a first transfer robot  128  is disposed substantially at the center of these processing devices, i.e. the aligner  122 , the cleaning/drying devices  124 , and the pretreatment device  126 , to thereby transfer and deliver a substrate between the processing devices  122 ,  124 , and  126 , the substrate attachment/detachment stages  162 , and the substrate cassettes mounted on the loading/unloading ports  120 . 
     The aligner  122 , the cleaning/drying devices  124 , and the pretreatment device  126  disposed in the clean space  114  are designed so as to hold and process a substrate in a horizontal state in which a front face of the substrate faces upward. The transfer robot  128  is designed so as to transfer and deliver a substrate in a horizontal state in which a front face of the substrate faces upward. 
     In the plating space  116 , in order from the partition plate  112 , there are disposed a stocker  164  for storing or temporarily storing the substrate holders  160 , an activation treatment device  166  for etching, for example, an oxide film, having a large electric resistance, on a seed layer formed on a surface of a substrate with a chemical liquid such as sulfuric acid or hydrochloric acid to remove the oxide film, a first rinsing device  168   a  for rinsing the surface of the substrate with pure water, a plating apparatus  170  for carrying out plating, a second rinsing device  168   b , and a blowing device  172  for dewatering the plated substrate. Two second transfer robots  174   a  and  174   b  are disposed beside these devices so as to be movable along a rail  176 . One of the second transfer robots  174   a  transfers the substrate holders  160  between the substrate attachment/detachment stages  162  and the stocker  164 . The other of the second transfer robots  174   b  transfers the substrate holders  160  between the stocker  164 , the activation treatment device  166 , the first rinsing device  168   a , the plating apparatus  170 , the second rinsing device  168   b , and the blowing device  172 . 
     As shown in  FIG. 2 , each of the second transfer robots  174   a  and  174   b  has a body  178  extending in a vertical direction and an arm  180  which is vertically movable along the body  178  and rotatable about its axis. The arm  180  has two substrate holder retaining portions  182  provided in parallel for detachably retaining the substrate holders  160 . The substrate holder  160  is designed so as to hold a substrate W in a state in which a front face of the substrate is exposed while a peripheral portion of the substrate is sealed, and to be capable of attaching the substrate W to the substrate holder  160  and detaching the substrate W from the substrate holder  160 . 
     The stocker  164 , the activation treatment device  166 , the rinsing devices  168   a ,  168   b , and the plating apparatus  170  are designed so as to engage with outwardly projecting portions  160   a  provided at both ends of each substrate holder  160  to thus support the substrate holders  160  in a state such that the substrate holders  160  are suspended in a vertical direction. The activation treatment device  166  has two activation treatment tanks  183  for holding a chemical liquid therein. As shown in  FIG. 2 , the arm  180  of the second transfer robot  174   b  holding the substrate holders  160 , which are loaded with the substrates W, in a vertical state is lowered so as to engage the substrate holders  160  with upper ends of the activation treatment tanks  183  to support the substrate holders  160  in a suspended manner as needed. Thus, the activation treatment device  166  is designed so that the substrate holders  160  are immersed together with the substrates W in the chemical liquid in the activation treatment tanks  183  to carry out an activation treatment. 
     Similarly, the rinsing devices  168   a  and  168   b  have two rinsing tanks  184   a  and two rinsing tanks  184   b  which hold pure water therein, respectively, and the plating apparatus  170  has a plurality of plating tanks  186  which hold a plating solution therein. The rinsing devices  168   a ,  168   b  and the plating apparatus  170  are designed so that the substrate holders  160  are immersed together with the substrates W in the pure water in the rinsing tanks  184   a ,  184   b  or the plating solution in the plating tanks  186  to carry out rinsing treatment or plating in the same manner as described above. The arm  180  of the second transfer robot  174   b  holding the substrate holders  160  with substrates W in a vertical state is lowered, and air or inert gas is injected toward the substrates W mounted on the substrate holders  160  to blow away a liquid attached to the substrate holders  160  and the substrates W and to dewater the substrates W. Thus, the blowing device  172  is designed so as to carry out blowing treatment. 
     As show in  FIGS. 3 and 4 , each plating tank  186  in the plating apparatus  170  is designed so as to hold a plating solution  10  therein. Thus, the substrates W, which are held in a state such that the front faces (surfaces to be plated) are exposed while peripheral portions of the substrate holders  160  are water-tightly sealed, are immersed in the plating solution  10 . 
     Overflow tanks  46  are provided at both sides of the plating tank  186  for receiving a plating solution  10  overflowing upper ends of overflow weirs  44  of the plating tank  186 . The overflow tanks  46  and the plating tank  186  are connected through a circulation pipe  48 . The circulation pipe  48  has a circulating pump  50 , a thermostatic unit  52 , and a filter  54  provided in the circulation pipe  48 . A plating solution  10  supplied into the plating tank  186  by operation of the circulating pump  50  fills the plating tank  186 , then overflows the overflow weirs  44 , flows into the overflow tanks  46 , and returns to the circulating pump  50 . Thus, the plating solution  10  is circulated. 
     An anode  56  having a circular shape corresponding to the shape of the substrate W is held by an anode holder  58  and provided vertically in the plating tank  186 . Thus, when the plating solution  10  is filled in the plating tank  186 , the anode  56  is immersed in the plating solution  10 . Further, a regulation plate  60  is provided between the anode  56  and the substrate holder  160  to partition the interior of the plating tank  186  into an anode side chamber  40   a  and a substrate side chamber  40   b  and to separate the plating solution  10  held in the plating tank  186  into an anode side plating solution and a substrate side plating solution. 
     A paddle-type agitating mechanism  64  having a plurality of paddles  62  extending vertically downward is disposed between the substrate holder  160  and the regulation plate  60 . The paddles  62  are reciprocated within the plating solution in the substrate side chamber  40   b  in parallel to the substrate W held by the substrate holder  160 , thereby stirring the plating solution in the substrate side chamber  40   b.    
     The regulation plate  60  has a thickness of, for example, about 0.5 to 10 mm and is made of a dielectric material including PVC, PP, PEEK, PES, HT-PVC, PFA, PTFE, and other resin materials. A through-hole group  68  including a large number of through-holes  66  is provided in a predetermined area of the regulation plate  60 , which is substantially the entire area facing the surface of the substrate W when the substrate W is held by the substrate holder  160  and located at a predetermined plating position in the plating tank  186 , and which is a circular area similar to the shape of the substrate W. 
     According to the present embodiment, as particularly shown in  FIG. 5 , the through-holes  66  are formed by slit-like elongated holes extending linearly in a horizontal direction. The through-holes (elongated holes)  66  are lineally arranged in parallel within a circular area corresponding to the shape of the substrate W so as to form the through-hole group  68 . The through-holes (elongated holes)  66  generally have a width of about 0.5 to 20 mm, preferably about 1 to 15 mm. The length of the through-hole  66  is determined depending upon the size (diameter) of the substrate W. 
     Thus, the through-hole group  68  including a large number of through-holes  66  is provided in the regulation plate  60  so that an electric field leaks through the respective through-holes  66  at the time of plating, and so that the leaked electric field spreads uniformly. Accordingly, a potential distribution can be made more uniform over the entire surface (surface to be plated) of the substrate W, and a within wafer uniformity of a metal film formed on the surface of the substrate W can be enhanced. Further, the plating solution  10  is prevented from passing through a large number of through-holes  66  formed in the regulation plate  60  provided in the plating tank  186 . Accordingly, a non-uniform metal film thickness is prevented from being formed on the surface of the substrate W due to influence of a flow of the plating solution  10  (return flow of the plating solution). 
     Particularly, the use of slit-like elongated holes as the through-holes  66  can prevent the plating solution  10  from passing through the through-holes (elongated holes)  66  and simultaneously promote leakage of the electric field. Further, by forming the through-hole group  68 , including a large number of through-holes  66  (i.e., minimize the amount of plating solution passing through), substantially in the entire area facing the surface of the substrate W which is a circular area similar to the shape of the substrate W, a metal film having a good film thickness uniformity can be formed in all directions on the surface of the substrate W. 
     With the plating apparatus  170 , a plating solution  10  is first filled in the plating tank  186  and circulated as described above. In this state, the substrate holder  160  holding the substrate W is lowered to locate the substrate W at a predetermined position within the plating tank  186  at which the substrate W is immersed in the plating solution  10 . The anode  56  is connected via a conductor  22   a  to an anode of a plating power supply  24 , and the substrate W is connected via a conductor  22   b  to a cathode of the plating power supply  24 . At the same time, the paddle-type agitating mechanism  64  is operated so as to reciprocate the paddles  62  along the surface of the substrate W to thereby agitate the plating solution  10  in the substrate side chamber  40   b . As a result, a metal is deposited on the surface of the substrate W so as to form a metal film on the surface of the substrate W. 
     At that time, as described above, an electric field leaks through a large number of through-holes  66  formed in the regulation plate  60 , and the leaked electric field spreads uniformly. Accordingly, a potential distribution can be made more uniform over the entire front face (surface to be plated) of the substrate W, and a metal film P having an enhanced within wafer uniformity can be formed on the surface of the substrate W as shown in  FIG. 6 . Further, by agitating the plating solution  10  between the substrate W and the regulation plate  60  with the paddles  62  during plating, the directionality of the flow of the plating solution can be eliminated, and simultaneously sufficient ions can be supplied more uniformly to the surface of the substrate W. Therefore, a metal film having a more uniform thickness can be formed more rapidly. 
     After completion of the plating, the plating power supply  24  is disconnected from the substrate W and the anode  56 , and the substrate holder  160  is pulled up together with the substrate W. After necessary treatments such as water-cleaning and rinsing of the substrate W, the plated substrate W is transferred to a subsequent process. 
     A series of bump plating processes in the plating facility thus constructed will be described below with reference to  FIGS. 7A through 7E . First, as shown in  FIG. 7A , a seed layer  500  is deposited as a feeding layer on a surface of a substrate W, and a resist  502  having a height H of, for example, about 20 to 120 μm is applied onto the entire surface of the seed layer  500 . Thereafter, an opening  502   a  having a diameter D 1  of, for example, about 20 to 200 μm is formed at a predetermined position of the resist  502 . Substrates W thus prepared are housed in a substrate cassette in a state such that front faces (surfaces to be plated) of the substrates face upward. The substrate cassette is mounted on the loading/unloading port  120 . 
     One of the substrates W is taken out of the substrate cassette mounted on the loading/unloading port  120  by the first transfer robot  128  and placed on the aligner  122  to align an orientation flat or a notch of the substrate with a predetermined direction. The substrate W thus aligned is transferred to the pretreatment device  126  by the first transfer robot  128 . In the pretreatment device  126 , a pretreatment (rinsing pretreatment) using pure water as a pretreatment liquid is carried out. On the other hand, two substrate holders  160  which have been stored in a vertical state in the stocker  164  are taken out by the second transfer robot  174   a , rotated through 90° so that the substrate holders  160  are brought into a horizontal state, and then placed in parallel on the substrate attachment/detachment stages  162 . 
     Then, the substrates W which have been subjected to the aforementioned pretreatment (rinsing pretreatment) are loaded into the substrate holders  160  placed on the substrate attachment/detachment stages  162  in a state such that peripheral portions of the substrates are sealed. The two substrate holders  160  which have been loaded with the substrates W are simultaneously retained, lifted, and then transferred to the stocker  164  by the second transfer robot  174   a . The substrate holders  160  are rotated through 90° into a vertical state and lowered so that the two substrate holders  160  are held (temporarily stored) in the stocker  164  in a suspended manner. The above operation is carried out repeatedly in a sequential manner, so that substrates are sequentially loaded into the substrate holders  160 , which are stored in the stocker  164 , and are sequentially held (temporarily stored) in the stocker  164  at predetermined positions in a suspended manner. 
     On the other hand, the two substrate holders  160  which have been loaded with the substrates and temporarily stored in the stocker  164  are simultaneously retained, lifted, and then transferred to the activation treatment device  166  by the second transfer robot  174   b . Each substrate is immersed in a chemical liquid such as sulfuric acid or hydrochloric acid held in the activation treatment tank  183  to thereby etch an oxide film, having a large electric resistance, formed on the surface of the seed layer so as to expose a clean metal surface. The substrate holders  160  which have been loaded with the substrates are transferred to the first rinsing device  168   a  in the same manner as described above to rinse the surfaces of the substrates with pure water held in the rinsing tanks  184   a.    
     The substrate holders  160  which have been loaded with the rinsed substrates are transferred to the plating apparatus  170  in the same manner as described above. Each substrate W is supported in a suspended manner by the plating tank  186  in a state such that the substrate W is immersed in the plating solution  10  in the plating tank  186  to thus carry out plating on the surface of the substrate W. After a predetermined period of time has elapsed, the substrate holders  160  which have been loaded with the substrates are retained again and pulled up from the plating tank  186  by the second transfer robot  174   b . Thus, the plating process is completed. 
     Thereafter, the substrate holders  160  are transferred to the second rinsing device  168   b  in the same manner as described above. The substrate holders  160  are immersed in pure water in the rinsing tanks  184   b  to clean the surfaces of the substrates with pure water. Then, the substrate holders  160  which have been loaded with the substrates are transferred to the blowing device  172  in the same manner as described above. In the blowing device  172 , inert gas or air is injected toward the substrates to blow away a plating solution and water droplets attached to the substrate holders  160 . Thereafter, the substrate holders  160  which have been loaded with the substrates are returned to predetermined positions in the stocker  164  and held in a suspended state in the same manner as described above. 
     The second transfer robot  174   b  sequentially performs the above operation repeatedly so that the substrate holders  160  which have been loaded with the plated substrates are sequentially returned to predetermined positions in the stocker  164  and held in a suspended manner. 
     On the other hand, the two substrate holders  160  which have been loaded with the plated substrates are simultaneously retained and placed on the substrate attachment/detachment stages  162  by the second transfer robot  174   a  in the same manner as described above. 
     The first transfer robot  128  disposed in the clean space  114  takes the substrate out of the substrate holders  160  placed on the substrate attachment/detachment stages  162  and transfers the substrate to either one of the cleaning/drying devices  124 . In the cleaning/drying device  124 , the substrate held in a horizontal state such that the front face of the substrate faces upward is cleaned with pure water or the like and rotated at a high speed to spin-dry the substrate. Thereafter, the substrate is then returned to the substrate cassette mounted on the loading/unloading port  120  by the first transfer robot  128 . Thus, a series of plating processes is completed. As a result, as shown in  FIG. 7B , a substrate W having a plated film  504  grown in the opening  502   a  formed in the resist  502  can be obtained. 
     The spin-dried substrate W as described above is immersed in a solvent such as acetone at a temperature of, for example, 50 to 60° C. to remove the resist  502  from the substrate W as shown in  FIG. 7C . Further, as shown in  FIG. 7D , an unnecessary seed layer  502 , which is exposed after plating, is removed. Next, the plated film  504  formed on the substrate W is reflowed to form a bump  506  having a round shape due to surface tension. The substrate W is then annealed at a temperature of, for example, 100° C. or more to remove residual stress in the bump  506 . 
     According to this embodiment, delivery of substrates in the plating space  116  is performed by the second transfer robots  174   a  and  174   b  disposed in the plating space  116 , whereas delivery of substrates in the clean space  114  is performed by the first transfer robot  128  disposed in the clean space  114 . Accordingly, it is possible to improve the cleanliness around a substrate in the plating processing apparatus which performs all the plating processes including pretreatment of a substrate, plating, and post-treatment of the plating, in a successive manner, and to increase a throughput of the plating processing apparatus. Further, it is possible to reduce loads on facilities associated with the plating processing apparatus and to achieve downsizing of the plating processing apparatus. 
     According to the present embodiment, a plating tank  186  having a small footprint is used in the plating apparatus  170  for carrying out plating. Accordingly, it is possible to achieve further downsizing of the plating apparatus having a large number of plating tanks  186  and reduce loads on associated facilities in a plant. In  FIG. 1 , one of the two cleaning/drying devices  124  may be replaced with a pretreatment device. 
       FIGS. 8 through 19  show various examples of a through-hole group including a large number of through-holes in a regulation plate  60 . Specifically,  FIG. 8  shows an example in which through-holes  66   a  are formed by slit-like elongated holes extending linearly in a vertical direction, and the through-holes (elongated holes)  66   a  are arranged linearly in parallel in a circular area corresponding to the shape of a substrate W so as to form a through-hole group  68   a .  FIG. 9  shows an example in which through-holes (elongated holes)  66   b  are arranged linearly in parallel in a rectangular area corresponding to the shape of a substrate W so as to form a through-hole group  68   b , which is suitable for a rectangular substrate W. 
       FIG. 10  shows an example in which a through-hole group  68   c  is formed by a plurality of through-holes (elongated holes)  66   c  which are slit-like elongated holes extending linearly substantially across the entire width of an area of a regulation plate  60  facing a surface of a substrate W. In this case, when a rectangular substrate W is used, as shown in  FIG. 11 , through-holes (elongated holes)  66   d  may be arranged in parallel in a rectangular area corresponding to the shape of the substrate W so as to form a through-hole group  68   d . Further, the through-holes  66   d  may be arranged so as to extend linearly in a vertical direction, which is not shown. 
       FIG. 12  shows an example in which through-holes (cross holes)  66   e  which are cross holes extending crosswise in vertical and horizontal directions are arranged uniformly in a circular area so as to form a through-hole group  68   e . In this case, when a rectangular substrate W is used, as shown in  FIG. 13 , through-holes (cross holes)  66   f  may be arranged uniformly in a rectangular area corresponding to the shape of the substrate W so as to form a through-hole group  68   f.    
       FIG. 14  shows an example in which a plurality of through-holes (fine holes)  66   g  which are fine holes is distributed uniformly in a circular area so as to form a through-hole group  68   g . In this illustrated example, the diameter of each through-hole (fine hole)  66   g  is set to be 2 mm, and 633 holes are provided in total. Although the diameters of the through-holes  66   g  as well as small holes (peripheral holes)  66   h   2  through  66   h   5  described below may be set arbitrarily within a range of, for example, 1 to 20 mm, they should preferably be in a range of about 2 to 10 mm. When the through-hole group  68   g  is formed by the through-holes (fine holes)  66   g , productivity of the regulation plate  60  can be increased. 
       FIG. 15  shows an example in which a through-hole group  68   h  is formed by a plurality of through-holes  66   h  having different diameters, i.e. a large hole (central hole)  66   h   1  having a large diameter and located at a central portion, and small holes (peripheral holes)  66   h   2  through  66   h   5  arranged outside of the large hole  66   h   1  along a circumferential direction in a plurality of arrays (four arrays in  FIG. 15 ) having diameters gradually reduced in a radial direction. The diameter of the large hole (central hole)  66   h   1  is set to be 84 mm in this example. Although the diameter of the large hole may be set arbitrarily within a range of, for example, 50 to 300 mm, it should preferably be in a range of about 30 to 100 mm. The diameters of the small holes (peripheral holes)  66   h   2  through  66   h   5  are set to be 10 mm, 8 mm, 7 mm, and 6 mm, respectively. 
       FIG. 16  shows an example in which a through-hole group  68 J is formed by a plurality of through-holes  66 J including a central hole  66   i   1  located at a central portion, and elongated holes  66   i   2  through  66   i   6  arranged outside of the central hole  66   i   1  along a circumferential direction in a plurality of arrays (five arrays in  FIG. 16 ). In this example, the diameter of the central hole  66   i   1  is set to be 34 mm, and the widths of the elongated holes  66   i   2  through  66   i   6  are set to be 27 mm, 18.5 mm, 7 mm, 7 mm, and 7 mm, respectively. 
       FIG. 17  shows an example in which a through-hole group  68   j  is formed by a plurality of through-holes  66   j  including a large hole (central hole)  66   j   1  having a large diameter and located at a central portion, elongated holes  66   j   2  arranged outside of the central hole  66   j   1  along a circumferential direction, and small holes (peripheral holes)  66   j   3  through  66   j   6  arranged outside of the elongated holes  66   j   2  in a plurality of arrays (four arrays in  FIG. 17 ) having diameters gradually reduced in a radial direction. In this example, the diameter of the large hole (central hole)  66   j   1  is set to be 67 mm, the width of the elongated hole  66   j   2  is set to be 17 mm, and the diameters of the small holes (peripheral holes)  66   j   3  through  66   j   6  are set to be 9 mm, 8 mm, 7 mm, and 6 mm, respectively. 
       FIG. 18  shows an example in which a through-hole group  68   k  is formed by a plurality of through-holes  66   k  including a large hole (central hole)  66   k   1  having a large diameter and located at a central portion, elongated holes  66   k   2 ,  66   k   3  arranged outside of the central hole  66   k   1 , along a circumferential direction in a plurality of arrays (two arrays in  FIG. 18 ), and small holes (peripheral holes)  66   k   4 ,  66   k   5  arranged outside of the elongated holes  66   k   3  in a plurality of arrays (two arrays in  FIG. 18 ) having diameters gradually reduced in a radial direction. In this example, the diameter of the large hole (central hole)  66   k   1  is set to be 80 mm, the widths of the elongated holes  66   k   2 ,  66   k   3  are set to be 7 mm, and the diameters of the small holes (peripheral holes)  66   k   4 ,  66   k   5  are set to be 6 mm and 4 mm, respectively. 
       FIG. 19  shows an example in which a through-hole group  68   l  is formed by a plurality of through-holes  661  including a large hole (central hole)  66   l   1  having a large diameter and located at a central portion, and a plurality of slit-like elongated holes  66   l   2  arranged outside of the central hole  66   l   1  at a predetermined pitch along a circumferential direction and extending linearly in a radial direction. The widths of the elongated holes  66   l   2  are generally in a range of about 0.5 to 20 mm, preferably about 1 to 15 mm. The lengths of the elongated holes  66   l   2  are set arbitrarily according to the shape of a plating workpiece. 
     Thus, a through-hole group is formed by a combination of a plurality of through-holes having desired shapes, such as a plurality of fine holes, a plurality of holes having different diameters, and slit-like elongated holes. Accordingly, a through-hole group can meet various requirements regarding plating sites, plating conditions, and the like. 
     In the examples shown in  FIGS. 14 through 19 , through-holes are arranged in a circular area so as to form a through-hole group. However, as described above, when a rectangular substrate is used, through-holes may be arranged, as a matter of course, in a rectangular area corresponding to the shape of the substrate so as to form a through-hole group. 
     As described above, according to the present invention, an electric field leaks through a large number of through-holes formed in a regulation plate provided in the plating tank, and the leaked electric field spreads uniformly. Accordingly, a potential distribution can be made more uniform over the entire surface of a plating workpiece, and a within wafer uniformity of a metal film formed on the surface of the plating workpiece can be enhanced. Further, a plating solution is prevented from passing through a large number of through-holes formed in the regulation plate provided in the plating tank  186 . Accordingly, non-uniform metal film thickness is prevented from being formed on the surface of the plating workpiece due to influence of a flow of the plating solution. 
       FIG. 20  shows a plating apparatus  170   a  according to another embodiment of the present invention, and  FIGS. 21A and 21B  show a regulation plate and a cylindrical member forming a plating solution passage which are used in the plating apparatus  170   a . The plating apparatus  170   a  differs from the apparatus shown in  FIGS. 3 through 5  in that the plating apparatus  170   a  employs a regulation plate  60  having a thickness of, for example, about 0.5 to 10 mm and having a central hole  60   a  at the center thereof which faces a substrate W held by a substrate holder  160  and has an inside diameter D corresponding to the outside diameter of the substrate W, and that a cylindrical member  200  having an inside diameter equal to the inside diameter D of the central hole  60   a  is concentrically connected to a surface of the regulation plate  60  on the substrate holder  160  side continuously (i.e., concentrically) with the central hole  60   a  so as to define a plating solution passage  200   a  inside an inner circumferential surface of the cylindrical member  200  for allowing an electric field to pass uniformly therethrough and allowing a plating solution  10  to pass therethrough. As with the regulation plate  60 , the cylindrical member  200  is made of a dielectric material including PVC, PP, PEEK, PES, HT-PVC, PFA, PTFE, and other resin materials. Other constructions are the same as those shown in  FIGS. 3 through 5 . 
     The inside diameters D of the central hole of the regulation plate  60  and the cylindrical member  200  are generally set to be approximately in a range of ±10 mm of an outside diameter (plated surface outside diameter) of a surface of a substrate W to be plated, preferably in a range of ±5 mm of an outside diameter of a surface to be plated, more preferably in a range of ±1 mm of an outside diameter of a surface to be plated. The length L of the cylindrical member  200  may properly be set depending upon the shape of the plating tank  186 , the distance between the anode  56  and the substrate W, and the like. However, the length L is generally set to be in a range of 10 to 90 mm, preferably 20 to 75 mm, more preferably 30 to 60 mm. 
     Thus, an electric field produced between the anode  56  and the substrate W in the plating tank  186  passes along the plating solution passage  200   a , i.e., passes uniformly through the cylindrical member  200  without leaking out of the cylindrical member  200 . Accordingly, distortion and deviation of the electric field can be adjusted and corrected so as to equalize a potential distribution over the entire surface of the substrate W. As a result, as shown in  FIG. 22 , a metal film P having an enhanced within wafer uniformity can be formed on the surface of the substrate W although it has a slightly thicker film at an edge portion of the substrate W. 
     Specifically, a regulation plate  60  generally is as thin as about 0.5 to 10 mm. Therefore, with a regulation plate  60  having only a central hole  60   a  formed therein, an electric field produced between the anode  56  and a substrate W in the plating tank  186  is not sufficiently regulated, and distortion or deviation of an electric field is caused. Accordingly, the substrate tends to be thicker at an edge portion, which serves as an electrically receiving portion. According to the present example, passing of an electric field is regulated over the length L of the cylindrical member  200 , so that the above drawback is solved. Thus, a within wafer uniformity of a metal film can be enhanced. 
     In this example, as in the examples shown in  FIGS. 3 through 5 , a paddle-type agitating mechanism  64  having a plurality of paddles  62  extending vertically downward is disposed between the cylindrical member  200  and the substrate W held by the substrate holder  160 . The paddle-type agitating mechanism  64  is operated during plating so as to reciprocate the paddles  62  along the surface of the substrate W, thereby agitating the plating solution  10  in a substrate side chamber  40   b . Accordingly, the directionality of the flow of the plating solution can be eliminated, and simultaneously sufficient ions can be supplied more uniformly to the surface of the substrate W. Therefore, a metal film having a more uniform thickness can be formed more rapidly. 
       FIG. 23  shows a plating apparatus  170   b  according to still another embodiment of the present invention. The plating apparatus  170   b  differs from the apparatus shown in  FIGS. 21 and 22  in that a plating solution injection type agitating mechanism  202  is disposed between the cylindrical member  200  and a substrate W held by the substrate holder  160  instead of the paddle-type agitating mechanism  64 . Specifically, the plating solution injection type agitating mechanism  202  has a plating solution supply pipe  204 , for example, in a ring shape, communicating with a circulation pipe  48  and immersed in the plating solution  10  in the plating tank  186 , and a plurality of plating solution injection nozzles  206  attached to predetermined portions of the plating solution supply pipe  204  along a circumferential direction for ejecting the plating solution  10  toward the substrate W held by the substrate holder  160 . A plating solution  10  fed by a pump  50  is supplied to the plating solution supply pipe  204  and injected from the plating solution injection nozzles  206  toward the substrate. Thus, the plating solution  10  is introduced into the plating tank  186 , overflows upper ends of overflow weirs  44 , and is circulated. 
     Thus, the plating solution  10  is injected from a plurality of plating solution injection nozzles  206  toward the substrate W. Accordingly, the plating solution  10  in the plating tank  186  can be agitated so as to make the plating solution concentration uniform and, simultaneously, to sufficiently supply components of the plating solution  10  to the substrate W. Thus, a metal film having a more uniform thickness can be formed more rapidly. 
     In this example, the cylindrical member  200  is coupled to a surface of the regulation plate  60  on the substrate W side. However, as shown in  FIG. 24B , an insertion hole  60   b  may be formed in the regulation plate  60 , and a cylindrical member  200  having an inside diameter D, a length L, and a plating solution passage  200   a  inside an inner circumferential surface thereof may be inserted into the insertion hole  60   b . In this manner, the cylindrical member  200  may be held at a predetermined position along a longitudinal direction of the cylindrical member  200 . This arrangement ensures a sufficient length L as the cylindrical member  200  even if a distance between the regulation plate  60  and the paddles  62  (see  FIG. 20 ) or the plating solution supply pipe  204  (see  FIG. 23 ) is short. 
     Further, as shown in  FIGS. 25A and 25B , the cylindrical member  200  may have a circumferential wall having a large number of through-holes  200   b  which have a size such as to prevent leakage of an electric field. With this arrangement, the plating solution  10  can pass through the through-holes  200   b  formed in the circumferential wall of the cylindrical member  200  while preventing leakage of the electric field. Accordingly, the concentration of the plating solution is prevented from being different between the inside and outside of the cylindrical member  200 . With respect to the shape of the through-holes, besides fine holes as in this example, slit-like elongated holes, cross holes extending vertically and horizontally, and a combination thereof may be exemplified. 
     Further, as shown in  FIGS. 26A and 26B , a regulation plate  210  may be formed by a plate having a sufficient thickness, and a through-hole having a predetermined inside diameter may be formed at a predetermined position in the regulation plate  210  so that the through-hole serves as a plating solution passage  210   a  having a predetermined inside diameter D and a predetermined length L. In such a case, the number of parts can be reduced. 
     Furthermore, as shown in  FIGS. 27A and 27B , a rectangular block  212  having a sufficient thickness may be prepared so that a through-hole formed in the rectangular block  212  serves as a plating solution passage  210   a  having a predetermined inside diameter D and a predetermined length L, and the rectangular block  212  may be connected to a surface of a regulation plate  60  having a center hole  60   a  on the substrate W side. 
       FIG. 28  shows a plating apparatus  170   c  according to yet another embodiment of the present invention, and  FIGS. 29A and 29B  shows a regulation plate, a cylindrical member forming a plating solution passage, and an electric field adjustment ring which are used in the plating apparatus  170   c  shown in  FIG. 28 . The plating apparatus  170   c  differs from the apparatus shown in  FIGS. 20 and 21  in the following points: An electric field adjustment ring  220  having the same inside diameter D as an inside diameter of the cylindrical member  200  and a width A is concentrically attached to a substrate W side end surface of the cylindrical member  200  having a plating solution passage  200   a  defined inside an inner circumferential surface thereof. The electric field adjustment ring  220  is disposed close to a substrate W with a gap G 1 . Further, the paddle-type agitating mechanism  64  having a plurality of paddles  62  extending vertically downward is disposed between the anode  56  and the regulation plate  60  in the anode side chamber  40   a  so as to reciprocate the paddles  62  in parallel to the substrate W held by the substrate holder  160 , thereby agitating the plating solution. Thus, the paddle-type agitating mechanism  64  agitates the plating solution  10  in the anode side chamber  40   a . Other constructions are the same as those shown in  FIGS. 20 and 21 . 
     As with the regulation plate  60  and the cylindrical member  200 , the electric field adjustment ring  220  is made of a dielectric material including PVC, PP, PEEK, PES, HT-PVC, PFA, PTFE, and other resin materials. Other elements of the construction are the same as those shown in  FIGS. 3 through 5 . The shape of the electric field adjustment ring  220  may properly be set depending upon the shapes of the plating tank  186  and the substrate W, the distance between the anode  56  and the substrate W, and the like. However, the width A is generally set to be in a range of 1 to 20 mm, preferably 3 to 17 mm, more preferably 5 to 15 mm. A gap G 1  between the electric field adjustment ring  220  and the substrate W is generally set to be in a range of 0.5 to 30 mm, preferably 1 to 15 mm, more preferably 1.5 to 6 mm. 
     The electric field adjustment ring  220  serves to adjust an electric field at a peripheral portion of the substrate W by covering a location near a peripheral portion of a substrate W over a predetermined width. Thus, an electric field is adjusted at a peripheral portion of the substrate W. Accordingly, an electric field produced between the anode  56  and the substrate W can be made uniform over the entire surface of the substrate W, including an edge portion of the substrate W, which serves as an electrically receiving portion. Therefore, as shown in  FIG. 30 , a metal film P having an enhanced within wafer uniformity can be formed on the surface of the substrate W, including the edge portion of the substrate. 
       FIG. 31  shows a plating apparatus  170   d  according to yet another embodiment of the present invention. The plating apparatus  170   d  has a plating solution injection type agitating mechanism  202 , which is shown in  FIG. 23 , disposed between the anode  56  and the regulation plate  60  in the anode side chamber  40   a , instead of the paddle-type agitating mechanism  64  used in the plating apparatus shown in  FIGS. 28 and 29 . Specifically, in this example, a plating solution  10  fed by a pump  50  is supplied to the plating solution supply pipe  204  and injected from the plating solution injection nozzles  206  toward a plating solution passage  200   a  of the cylindrical member  200 . Thus, the plating solution  10  is introduced into the plating tank  186 , overflows upper ends of overflow weirs  44 , and is circulated. Other elements of the construction are the same as those shown in  FIGS. 28 and 29 . 
     Thus, the plating solution injection type agitating mechanism  202  is disposed in the anode side chamber  40   a , and the plating solution is injected from the plating solution injection nozzles  206  toward the plating solution passage  200   a  of the cylindrical member  200 . The plating solution can be supplied through the plating solution passage  200   a  to the substrate W held by the substrate holder  160  even if a gap G 1  between an electric field adjustment ring  220  and the substrate W held by the substrate  160  is narrow. 
     As shown in  FIGS. 32A and 32B , an insertion hole  60   b  may be formed in the regulation plate  60 , and a cylindrical member  200  having an inside diameter D, a length L, a plating solution passage  200   a  inside an inner circumferential surface thereof, and an electric field adjustment ring  220  attached to an end surface thereof may be inserted into the insertion hole  60   b  substantially in the same manner as shown in  FIGS. 24A and 24B . Thus, the cylindrical member  200  may be held at a predetermined position along a longitudinal direction of the cylindrical member  200 . 
     As shown in  FIGS. 33A and 33B , a large number of through-holes  200   b  having a size such as to prevent leakage of an electric field may be formed in a circumferential wall of a cylindrical member  200  having an electric field adjustment ring  220  attached to an end surface thereof substantially in the same manner as shown in  FIGS. 25A and 25B . Thus, the plating solution  10  can pass through the through-holes  200   b  formed in the circumferential wall of the cylindrical member  200  while preventing leakage of the electric field. 
     Further, as shown in  FIGS. 34A and 34B , the electric field adjustment ring  220  may not be fixed to the end surface of the cylindrical member  200 , but may be supported by a support  222  so as to have a gap G 2  between the front of the substrate W side end surface of the cylindrical member  200  and the substrate W. As with the gap G 1  between the electric field adjustment ring  220  and the substrate W, the gap G 2  is generally set to be in a range of 0.5 to 30 mm, preferably 1 to 15 mm, more preferably 1.5 to 6 mm. With the plating solution passage  200   a  thus formed, the cylindrical member  200  and the electric field adjustment ring  220  can be separated so as to offer a broader choice. 
     As shown in  FIGS. 35A and 35B , a plating solution passage  224   a  having a predetermined inside diameter D and a length L may be defined by an inner circumferential surface of a thick ring  224  having a sufficient thickness, and an electric field adjustment ring  224   b  having a predetermined width A may be formed by a substrate side end surface of the thick ring  224 . In this case, the number of parts can be reduced. 
     Although the aforementioned examples show that the present invention is applied to a so-called dipping type plating apparatus, the present invention is also applicable to a face-down type plating apparatus or a face-up type plating apparatus. 
       FIG. 36  shows an example in which the present invention is applied to a face-down type plating apparatus. In this example, the following structures are added to a conventional plating apparatus shown in  FIG. 37 . Specifically, a regulation plate  230  having a central hole  230   a  formed therein is disposed at an upper position of the plating tank  12  so as to separate the interior of the plating tank  12  into an anode side chamber  12   a  and a substrate side chamber  12   b . Further, a cylindrical member  232  having an inside diameter equal to the diameter of the central hole  230   a  and an inner circumferential surface forming a plating solution passage  232   a  is concentrically attached to an upper surface of the regulation plate  230  in a manner so as to project upward. With this arrangement, an electric field produced between the anode  16  and a substrate W in the plating tank  12  can pass along the plating solution passage  232   a , i.e. uniformly through the cylindrical member  232  without leaking out of the cylindrical member  232 . Accordingly, distortion and deviation of the electric field can be adjusted and corrected so as to equalize a potential distribution over the entire surface of the substrate W. 
     An electric field adjustment ring having an inside diameter equal to an inside diameter of the cylindrical member and a predetermined width may concentrically be attached to an upper end surface of the cylindrical member so as to cover a location near a peripheral portion of the substrate W over a predetermined width. Thus, an electric field can be adjusted at the peripheral portion of the substrate W. Accordingly, an electric field produced between the anode  56  and the substrate can be made uniform over the entire surface of the substrate, including an edge portion of the substrate, which serves as an electrically receiving portion. Therefore, a metal film having an enhanced within wafer uniformity can be formed on the surface of the substrate, including the edge portion of the substrate.