Abstract:
A magnetic film plating apparatus employs a dip method that allows relatively good escape of bubbles and does not require a wide footprint and, even when a ferromagnetic material is used for an anode, can form a magnetic film on a substrate surface while minimizing the influence of the anode on the uniformity of magnetic anisotropy in the magnetic film. The magnetic film plating apparatus includes a plating tank for holding a plating solution; an anode vertically disposed in the plating tank at a position to be immersed in the plating solution; a substrate holder for holding a substrate W and positioning the substrate W opposite the anode; and a magnetic field generator, disposed outside the plating tank, for generating a magnetic field around the substrate W held by the substrate holder and positioned opposite the anode.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a magnetic film plating apparatus and method, and more particularly to a magnetic film plating apparatus and method which is useful for forming a magnetic film on an exposed surface of a metal layer formed in a surface of a substrate, such as a semiconductor wafer. 
         [0003]    2. Description of the Related Art 
         [0004]    As a technique for forming a magnetic film on a device, such as an MRAM or a magnetic head, by electroplating, a method is known, for example, which comprises immersing a substrate, which is held in a horizontal position with a surface to be plated (front surface) of the substrate facing downwardly, in a plating solution in a plating tank, and passing a plating current between the substrate and an anode disposed parallel to the substrate while forming a horizontal magnetic field around the substrate by means of electromagnets (or permanent magnets) disposed on opposite sides of the plating tank (see Japanese Patent laid-Open Publication No. H5-17898). Further, it has been proposed to use, besides a main magnet, an auxiliary magnet for correcting a main magnetic field formed by the main magnet so as to provide a magnetic field parallel to a substrate (see Japanese Patent laid-Open Publication No. S61-190091). 
         [0005]    The applicant has proposed a plating apparatus for carrying out a sequence of process steps for plating, such as copper plating, on a surface of a substrate such as a semiconductor wafer, comprising a substrate holder for holding a substrate; a substrate attachment/detachment section for attaching and detaching the substrate to and from the substrate holder; a plating tank for carrying out plating; and a substrate holder transport apparatus for transporting the substrate holder (see Japanese Patent No. 3979847). In this plating apparatus, a substrate in a vertical position is immersed in a plating solution in the plating tank. Therefore, this plating apparatus has the advantages of relatively good escape of bubbles during plating, narrow footprint of the apparatus and good suitability for automation of the apparatus. 
       SUMMARY OF THE INVENTION 
       [0006]    In the case where a magnetic film is formed by electroplating on a surface (surface to be plated) of a substrate which is held horizontally with the surface facing downwardly and immersed in a plating solution in a plating tank, however, escape of bubbles is generally poor. In addition, such a plating apparatus needs a wide footprint and automation of the apparatus is generally difficult. 
         [0007]    In the formation of a magnetic film by electroplating, a ferromagnetic material is sometimes used for an anode. When using a ferromagnetic material for an anode and forming a magnetic film on a surface (surface to be plated) of a substrate by electroplating while forming a magnetic field around the substrate, due to the presence of the anode of ferromagnetic material, magnetic field lines will deviate from a reference direction by a certain angle, making it difficult to equalize the magnetic density in the substrate surface. Such non-uniformity of the magnetic density in the substrate surface affects uniformity of the magnetic anisotropy in the magnetic film formed on the substrate. The use of the auxiliary magnet described in the above-cited patent document is not in consideration of the influence of an anode; and therefore it is considered that when a ferromagnetic material is used for an anode, the presence of the anode (ferromagnetic material) will affect the uniformity of magnetic anisotropy in a magnetic film formed on a substrate. 
         [0008]    The present invention has been made in view of the above situation. It is therefore an object of the present invention to provide a magnetic film plating apparatus and method which employs a dip method that allows relatively good escape of bubbles and does not require a wide footprint and which, even when a ferromagnetic material is used for an anode, can form a magnetic film on a substrate surface while minimizing the influence of the anode on the uniformity of magnetic anisotropy in the magnetic film. 
         [0009]    In order to achieve the above object, the present invention provides a magnetic film plating apparatus comprising: a plating tank for holding therein a plating solution; an anode vertically disposed in the plating tank at a position to be immersed in the plating solution; a substrate holder for holding a substrate and positioning the substrate opposite the anode; and a magnetic field generator, disposed outside the plating tank, for generating a magnetic field around the substrate held by the substrate holder and positioned opposite the anode. 
         [0010]    The plating apparatus employs a dip method that allows relatively good escape of bubbles and does not require a wide footprint, and can form a magnetic film on a substrate surface. 
         [0011]    The magnetic field generator is comprised, for example, of an electromagnet disposed around the plating tank. 
         [0012]    The magnetic field generator may be comprised of a permanent magnet disposed around the plating tank. 
         [0013]    Preferably, a first dummy anode, having a larger size than the substrate and surrounding the circumference of the anode, is disposed on the circumference of the anode. 
         [0014]    When a ferromagnetic material, such as nickel, is used for the anode, the first dummy anode can reduce deviation of the magnetic flux in a substrate surface from a reference direction. 
         [0015]    The first dummy anode preferably has a rectangular shape. 
         [0016]    The first dummy anode is at a right angle to the reference direction of the magnetic flux. Accordingly, the use of the first dummy anode in a rectangular shape can make magnetic field lines in the vicinity of a substrate closer to the reference direction. 
         [0017]    Preferably, a second dummy anode is disposed on the opposite side of the substrate, held by the substrate holder and positioned opposite the anode, from the anode. 
         [0018]    The use of the second dummy anode can reduce inclination of magnetic field lines from the vertical direction toward the normal direction of the substrate. 
         [0019]    The second dummy anode preferably has the same shape and size as the sum of the anode and the first dummy anode. 
         [0020]    Preferably, the surface of the substrate held by the substrate holder, the anode, the first dummy anode and the second dummy anode are disposed parallel to each other in the plating tank. 
         [0021]    Preferably, the substrate held by the substrate holder is disposed at the center of a space in which the magnetic field is formed by the magnetic field generator. 
         [0022]    Preferably, a stirring paddle for stirring the plating solution in the plating tank is disposed in the plating tank. 
         [0023]    The use of the stirring paddle can make the flow of the plating solution along the surface of the substrate more uniform over an entire substrate surface, making it possible to form a magnetic film (plated film) with a more uniform thickness over the entire substrate surface. 
         [0024]    Preferably, an electric field regulation plate for regulating the electric field in the plating tank is disposed in the plating tank. 
         [0025]    Preferably, a tray for preventing the plating solution from dropping downward is retractably provided under the substrate holder. 
         [0026]    The use of the tray can prevent the plating solution, dropping off the substrate holder, from falling onto an electromagnet and the outside of the plating tank when withdrawing the substrate holder from the plating tank after plating and transporting the substrate holder. 
         [0027]    The plating tank is preferably provided with an air bag for fixing the substrate holder in a predetermined position. 
         [0028]    The use of the air bag enables the substrate holder to be fixed in a predetermined position without using a magnet which may distribute the magnetic field in the plating tank. 
         [0029]    Preferably, exhaust ducts are provided at positions along the side of the magnetic field generator. 
         [0030]    By creating flows of air flowing from the plating tank toward the exhaust ducts, and discharging a vapor evaporating from the plating solution with the flows of air, contamination of a substrate with the vapor can be prevented. An arbitrary number of exhaust ducts may be provided. 
         [0031]    Preferably, the substrate holder is provided with a notch pin which, when the substrate is held by the substrate holder, enters a notch portion of the substrate to align the direction of the substrate with respect to the substrate holder. 
         [0032]    When the substrate is held by the substrate holder after aligning the direction of the notch portion of the substrate with respect to the substrate holder, e.g., by an aligner, the direction of the notch portion of the substrate with respect to the substrate holder can always be made precisely constant. 
         [0033]    The present invention also provides a magnetic film plating method comprising: vertically disposing an anode and a substrate opposite each other in a plating solution; and applying a plating voltage between the anode and the substrate while forming a magnetic field around the substrate, thereby forming a magnetic film on a surface of the substrate. 
         [0034]    The present invention also provides a plating facility comprising: the magnetic film plating apparatus; an aligner for aligning the direction of a substrate; and a main frame in which the magnetic film plating apparatus and the aligner are housed. 
         [0035]    The plating tank of the magnetic film plating apparatus is preferably provided in a plural number in the main frame. 
         [0036]    Preferably, one or more of a pre-wetting tank, a pre-soaking tank, a blow tank and a rinsing tank are housed in the main frame. 
         [0037]    This enables a series of plating process steps to be carried out successively in the same facility. 
         [0038]    Preferably, the plating facility further comprises a substrate holder transport apparatus for transporting the substrate holder of the magnetic film plating apparatus, and the substrate held by the substrate holder is transported between the tanks. 
         [0039]    Two substrate holders may be placed laterally slidably and parallel to each other on a substrate attachment/detachment section. This enables the use of a single opening/closing mechanism for opening and closing the two substrate holders and, in addition, can eliminate the need to laterally move the substrate transport apparatus. 
         [0040]    According to the present invention, a dip method, which does not require a wide footprint, can be employed and, even when a ferromagnetic material is used for an anode, a magnetic film having magnetic anisotropy can be formed on a substrate surface while minimizing the influence of the anode on the uniformity of the magnetic anisotropy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]      FIG. 1  is an overall plan view of a plating facility according to an embodiment of the present invention; 
           [0042]      FIG. 2  is a front view showing a substrate holder transport apparatus holding substrate holders; 
           [0043]      FIG. 3  is a perspective view showing the main portion of the substrate holder transport apparatus holding the substrate holders; 
           [0044]      FIG. 4  is a partly-omitted plan view of a substrate holder; 
           [0045]      FIG. 5  is a vertical sectional front view of the substrate holder; 
           [0046]      FIG. 6  is a right side view of the substrate holder; 
           [0047]      FIGS. 7A through 7C  are diagrams illustrating the process of mounting a substrate to the substrate holder while precisely aligning the direction of a notch portion of the substrate; 
           [0048]      FIG. 8  is a schematic view of a magnetic film plating apparatus according to an embodiment of the present invention; 
           [0049]      FIG. 9  is a plan view of a stirring paddle; 
           [0050]      FIG. 10  is a cross-sectional view taken along line A-A of  FIG. 9 ; 
           [0051]      FIGS. 11A and 11B  are cross-sectional views equivalent to  FIG. 10 , showing variations of the stirring paddle; 
           [0052]      FIG. 12  is a schematic view showing a paddle drive mechanism of the magnetic film plating apparatus shown in  FIG. 8  together with a plating tank; 
           [0053]      FIG. 13A  is a cross-sectional diagram illustrating the relationship between a substrate holder receiver, provided in an upper surface of a surrounding wall of the plating tank, and a hand of the substrate holder before fixing of the hand, and  FIG. 13B  is across-sectional diagram illustrating the relationship between the substrate holder receiver, provided in the upper surface of the surrounding wall of the plating tank, and the hand of the substrate holder after fixing of the hand; 
           [0054]      FIG. 14  is a plan view showing another example of plating tank and magnetic field generator; 
           [0055]      FIG. 15  is a plan view showing yet another example of plating tank and magnetic field generator; 
           [0056]      FIG. 16  is a plan view showing yet another example of plating tank and magnetic field generator; 
           [0057]      FIG. 17  is a diagram illustrating the positional relationship between a substrate holder, a plating tank and a magnetic field generator in a magnetic film plating apparatus according to another embodiment of the present invention; 
           [0058]      FIG. 18  is a schematic view of a magnetic film plating apparatus according to yet another embodiment of the present invention; 
           [0059]      FIG. 19  is a plan view of  FIG. 18 ; 
           [0060]      FIG. 20A  is a perspective view showing an anode and a first dummy anode, and  FIG. 20B  is a vertical sectional front view showing the anode and the first dummy anode; 
           [0061]      FIG. 21  is a vertical sectional front view showing another anode and first dummy anode; 
           [0062]      FIGS. 22A through 22C  are diagrams illustrating various relationships between the direction of a substrate, the direction of a magnetic field and the direction of the flow of plating solution; and 
           [0063]      FIG. 23  is an enlarged view of the main portion of  FIG. 18 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0064]    Preferred embodiments of the present invention will now be described with reference to the drawings. In the following embodiments, a magnetic film of permalloy (Ni/Fe=80/20%) is formed on a surface (surface to be plated) of a substrate, such as a semiconductor wafer. A plating solution capable of forming permalloy is used. An anode of nickel (Ni), which is a ferromagnetic material, or an insoluble anode (e.g., Ti coated with IrO 2  or Ti cladded with 1-μm Pt) may be used. Besides a permalloy magnetic film, a magnetic film of cobalt or a cobalt alloy, for example, can also be formed. 
         [0065]      FIG. 1  shows an overall layout plan of a plating facility according to an embodiment of the present invention. This plating facility performs the whole plating process for a substrate, including pre-plating treatment, plating and post-plating treatment, automatically in a successive manner. The plating facility includes a main frame  10  with a face panel attached thereto. The interior of the main frame  10  is separated by a partition plate  12  into a plating space  14  where plating of a substrate and treatment of the substrate to which a plating solution adheres are carried out, and a cleaning space  16  where the other treatments, not directly associated with a plating solution, are carried out. To the cleaning space  16  is connected a loading/unloading port  18  in which is mounted a substrate cassette, such as FOUP (front opening unified pod), in which substrates such as semiconductor wafers are housed. The main frame  10  is provided with an operation panel (not shown). 
         [0066]    In the clean space  16 , there are disposed a substrate transport robot  20  for carrying in and carrying out a substrate in a substrate cassette mounted in the loading/unloading port  18 , and for transporting a substrate, an aligner  22  for aligning an orientation flat or a notch of a substrate with a predetermined direction, a cleaning/drying device  24  for cleaning (rinsing) a plated substrate with a cleaning liquid, such as pure water, and rotating the substrate at a high speed to dry the substrate, a substrate attachment/detachment section  28 , as a substrate transfer section, for attaching and detaching substrates between it and two substrate holders  26  (see  FIGS. 2 and 4 ), which are disposed parallel. 
         [0067]    The substrate transport robot  20  disposed in the clean space  16  is designed so as to hold a substrate and carry in and carry out the substrate in a horizontal state in which a front face (surface to be plated) of the substrate faces upward. The aligner  22  and the cleaning/drying device  24  are designed so as to hold and process a substrate in a horizontal state in which a front face (surface to be plated) of the substrate faces upward. 
         [0068]    In the plating space  14 , in the order from the partition plate  12 , there are disposed four pair (total eight) of stocker tanks  30  for storing or temporarily storing the substrate holders  26 , a pair of pre-wetting tanks  32  for enhancing a hydrophilicity of the substrate surface by immersing into and wetting with pure water, a pair of pre-soaking tanks  34  for etching away an oxide film, having a large electric resistance, on a seed layer formed on the surface of the substrate with a liquid chemical, such as sulfuric acid or hydrochloric acid, a pair of blow tanks  36  for dewatering the substrate after rinsing (cleaning), a pair of rinsing tanks  38  for rinsing (cleaning) the plated substrate with pure water, and two pair (total four) of plating tanks  40 . In the main frame  10 , a pair of service tanks  42  for putting in and taking out the substrate holders  26  and the anode holder  222  (see  FIG. 8 ) from the apparatus therethrough are provided between the main frame  10  and the plating tanks  40 . 
         [0069]    In this embodiment, as shown in  FIG. 8 , a substrate holder  26 , a plating tank  40  and a magnetic field generator  114 , comprised of a cylindrical electromagnet  112  disposed around the plating tank  40 , constitute a magnetic film plating apparatus  110 . 
         [0070]    Lateral to the substrate attachment/detachment section  28  and the above tanks is disposed a substrate holder transport apparatus  46  having a transport rail  44  linearly extending along the substrate attachment/detachment section  28  and the tanks, and a transporter  45  which travels on the transport rail  44  while holding two substrate holders  26 . As shown in  FIGS. 2 and 3 , the transporter  45  includes a vertically-extending body  47  which travels on the transport rail  44 , and an arm  48  which is vertically movable along the body  47  and rotatable about its axis. In the arm  48  are provided two parallel substrate holding sections  49  each for detachably holding a substrate holder  26 . 
         [0071]    To the base end of the arm  48  is vertically mounted a rotating shaft  51  which is rotatable by a rotation mechanism  50 , and to the lower end of the rotating shaft  51  is coupled a base end of a horizontally-extending tray  52 . The tray  52  opens upward and has a semicircular cross-section and, at its rotating shaft  51  side end, is provided with a drain  53  for discharging downward a plating solution corrected in the tray  52 . With this structure, when withdrawing the substrate holders  26  from the plating tanks  40  and transporting the substrate holders  26 , a plating solution dropping from the lower ends of the substrate holders  26  is received by the tray  52  positioned right under the substrate holders  26 . This can prevent the plating solution from falling, e.g., onto the electromagnet  112  (magnetic field generator  114 ) or other devices lying outside the plating tanks  40 . The tray  52  can be rotated to the retracted position, shown by the broken lines in  FIG. 3 , by the rotation mechanism  50  so that the tray  52  will not encumber the vertical movements of the substrate holders  26 . 
         [0072]    As described above, each substrate holder  26 , together with each plating tank  40  and a magnetic field generator  114 , comprised of a cylindrical electromagnet  112  disposed around the plating tank  40 , constitutes a magnetic film plating apparatus  110  (see  FIG. 8 ). Each substrate holder  26  also functions to transport a substrate between the tanks by the substrate holder transport apparatus  54  while holding the substrate. 
         [0073]    As shown in  FIGS. 4 through 7 , the substrate holder  26  has a fixed holding member  54  made of, for example, a vinyl chloride resin in the form of a rectangular flat plate, and a movable holding member  58  mounted openably and closably via a hinge  56  on the fixed holding member  54 . While the movable holding member  58  is shown as being openably and closably mounted on the fixed holding member  54  by the hinge  56  in present embodiment, the movable holding member  58  may be disposed in a position facing the fixed holding member  54  and may be moved forward to the fixed holding member  54  so as to be opened and closed with respect thereto. 
         [0074]    The movable holding member  58  has a base portion  58   a  and, in this embodiment, a ring-shaped support portion  58   b , and is made of, for example, a vinyl chloride resin for better slippage against a below-described press ring  62 . A ring-shaped sealing member (seal ring)  60  that is of a substantially channel-shaped transverse cross section having two lips, one being longer than the other, is mounted on a surface of the support portion  58   b , which faces the fixed holding member  54 , of the moveable holding member  58 . The ring-shaped sealing member  60  is open toward the fixed holding member  54 . A press ring  62  is rotatably supported on a surface of the moveable holding member  58  on the far side from the fixed holding member  54 , and slide plates  64  are jointed to outer circumferential surfaces of the press ring  62 . The press ring  62  is made of, for example, titanium that is highly resistant to corrosion in oxidizing environments and has sufficient rigidity. 
         [0075]    Inverted L-shaped clampers  70 , each having an inward protrusion, are vertically mounted on the fixed holding member  54  at circumferentially equal spaced intervals in positions laterally outward of the slide plates  64 . The surfaces of the slide plates  64 , and the lower surfaces of the inward protrusions of the clampers  70 , which are positioned in covering relation to the surfaces of the slide plates  64 , are tapered so as to be slanted oppositely to each other in the rotational direction. Projections  73 , which comprise rotary pins threaded into the press ring  62 , for example, are mounted on the surface of the press ring  62  respectively in a plurality of locations (e.g., four locations) along the circumferential direction of the press ring  62 . The projections  73  are engaged by a rotating mechanism for rotating the press ring  62  in unison with the slide plates  64 . 
         [0076]    When the movable holding member  58  is open, the substrate W is inserted into the center of the fixed holding member  54 . After the movable holding member  58  is closed about the hinge  56 , the press ring  62  is turned clockwise to cause the slide plates  64  to slide into the protrusions of the clampers  70 , thereby fastening and locking the fixed holding member  54  and the movable holding member  58  to each other through their tapered surfaces. By turning the press ring  62  counterclockwise, the slide plates  64  are removed from the protrusions of the L-shaped clampers  70 , unlocking the fixed holding member  54  and the movable holding member  58  from each other. When the movable holding member  58  is locked, a shorter lip  60   a  (see  FIG. 7 ) on the inner circumferential surface of the sealing member  60  is in pressure contact with the surface of the substrate W, and a longer lip  60   b  (see  FIG. 7 ) on the outer circumferential surface of the sealing member  60  is in pressure contact with the surface of the fixed holding member  54 , respectively. The sealing member  60  is thus uniformly pressed against the substrate W and the fixed holding member  54  to seal the surface of the substrate W and the surface of the fixed holding member  154  reliably. 
         [0077]    A ridge  82  is mounted centrally on and projects from the fixed holding member  54  in a ring shape matching the size of the substrate W. The ridge  82  provides a support surface  80  for abutting against the peripheral edge of the substrate W to support the substrate W thereon. The ridge  82  has a plurality of recesses  84  defined therein at predetermined positions along the circumferential direction thereof. A plurality of (eight in the illustrated embodiment) conductors (electrical contacts)  88  are disposed respectively in the recesses  84  and connected to respective wires extending from external contacts on a below-described hand  98 . The conductors  88  have their springy ends exposed on the surface of the fixed holding member  54  laterally of the substrate W when the substrate W is placed on the support surface  80  of the fixed holding member  54 . 
         [0078]    A support body (see  FIG. 7 )  90  is mounted in an inner space of the sealing member  60  which is defined between the pair of lips  60   a ,  60   b . Electrical contacts  92  have respective legs  92   a  fixed to the support body  90  at positions confronting the conductors  88 . Each electrical contact  92  is formed in a leaf springs shape. Specifically, the electrical contacts  92  have contact ends  92   b  projecting inwardly as leaf springs that can easily flex under their own resiliency. 
         [0079]    The movable holding member  58  is opened and closed by a cylinder (not shown) and the weight of the movable holding member  58  per se. Specifically, the fixed holding member  54  has a through-hole  54   a , as shown in  FIG. 6 , and a cylinder is disposed in a position which confronts the through-hole  54   a  of the substrate holder  26  placed on a loading plate (not shown) of the substrate attachment/detachment section  28 . When the piston rod of the cylinder is extended to cause a pusher rod to lift the base portion  58   a  of the movable holding member  58  through the through-hole  54   a , thereby opening the movable holding member  58 . When the piston rod is contracted, the movable holding member  58  is closed under its own weight. 
         [0080]    In the present embodiment, the press ring  62  is rotated to lock and unlock the movable holding member  58 . A locking/unlocking mechanism for locking and unlocking the movable holding member  58  is mounted on the ceiling side. The locking/unlocking mechanism has gripping members disposed in respective positions aligned with the projections  73  of the press ring  62  of the centrally positioned substrate holder  26  placed on the loading plate of the substrate attachment/detachment section  28 . The locking/unlocking mechanism is arranged to rotate the press ring  62  when the gripping members are turned about the axis of the press ring  62  with the loading plate of the substrate attachment/detachment section  28  being lifted and the projections  73  being gripped by the gripping members. There is a single locking/unlocking mechanism being used, and after the locking/unlocking mechanism locks (or unlocks) one of two substrate holders  26  placed on the loading plate of the substrate attachment/detachment section  28 , the loading plate of the substrate attachment/detachment section  28  is slid horizontally, and the locking/unlocking mechanism locks (or unlocks) the other substrate holder  26 . 
         [0081]    A pair of substantially T-shaped hands  98  is jointed to an end of the fixed holding member  54  of the substrate holder  26 . The stocker tank  30  is designed so as to engage on an upper surface of a surrounding wall with outwardly projecting portions of the hands  98  of each substrate holder  26  to thus support the substrate holders  26  in such a state that the substrate holders  26  are suspended in a vertical direction. The hands  98  of the substrate holder  26  suspended in a vertical direction are gripped by the transporter  45  of the substrate transport apparatus  46  for transporting the substrate holder  26 . The pre-wetting tank  32 , the pre-soaking tank  34 , the blow tank  36 , the rinsing tank  38  and plating tank  40  are also designed so as to support the substrate holders  26  on surrounding walls by the hands  98  such a state that the substrate holders  26  are suspended in a vertical direction. 
         [0082]    In plating of a magnetic film, it is sometimes necessary to apply a magnetic field precisely in a predetermined direction with respect to a structure formed on a substrate. For this purpose, it is desired to impart to the substrate holder  26  a misalignment prevention function which, after aligning the direction of a notch portion of a substrate W with respect to the substrate holder  26  by the aligner  22 , always makes the direction of the notch portion of the substrate W with respect to the substrate holder  26  precisely constant. In this embodiment, as shown in  FIGS. 7A through 7C , a rod-like first spring member (notch pin)  100  is mounted to the fixed holding member  54  at a position corresponding to the notch portion of the substrate W, and a plate-like second spring member  102  is mounted to the movable holding member  58  at a position corresponding to the notch portion of the substrate W. When holding the substrate W between the fixed holding member  54  and the movable holding member  58 , the second spring member  102  presses the first spring member  100  inwardly, as shown in FIG.  7 B, whereby the front end of the first spring member (notch pin)  100  is inserted into the inwardly-curved notch portion of the substrate W, as shown in  FIG. 7C . Misalignment of the direction of the notch portion of the substrate W with respect to the substrate holder  26  can thus be prevented. 
         [0083]    Though the two spring members, the first spring member  100  and the second spring member  102 , are used in this embodiment, it is also possible to integrate the first spring member  100  and the second spring member  102 . Though it is preferred that a rod-like spring member (notch pin) be inserted into the notch portion of a substrate W when the substrate W is held by a substrate holder  26 , and the rod-like spring member (notch pin) separate from the notch portion of the substrate W when the holding of the substrate W by the substrate holder  26  is released, it is also possible to allow a stationary pin to be inserted into the notch portion of a substrate without using an elastically deformable member. By thus utilizing the operation of holding the substrate W between the fixed holding member  54  and the movable holding member  58 , and causing the elastic members, such as a plate spring, to deform, the misalignment prevention mechanism can be constructed with a relatively simple structure. 
         [0084]      FIG. 8  schematically shows the magnetic film plating apparatus  110 . As shown in  FIG. 8 , the magnetic film plating apparatus  110  mainly comprises the above-described substrate holder  26 , a plating tank  40  and a magnetic field generator  114  comprised of a cylindrical electromagnet  112  disposed around the plating tank  40 . 
         [0085]    The plating tank  40  includes a plating tank body  186  for holding a certain amount of plating solution Q in which a substrate W, held by the substrate holder  26  with its peripheral portion watertightly sealed by the seal member  60  (see  FIGS. 7A through 7C ) and its front surface (surface to be plated) exposed, is to be immersed in a vertical position. An overflow tank  200  for receiving the plating solution Q that has overflowed an edge of the plating tank body  186  is provided around an upper portion of the plating tank body  186 . One end of circulation piping  204 , which is provided with a pump  202 , is connected to the bottom of the overflow tank  200 , and the other end of the circulation piping  204  is connected to a plating solution supply inlet  186   a  provided at the bottom of the plating tank body  186 . Thus, the plating solution Q corrected in the overflow tank  200  is returned into the plating tank body  186  by the actuation of the pump  202 . Located downstream of the pump  202 , a constant-temperature unit  206  for controlling the temperature of the plating solution Q, and a filter  208  for filtering out foreign matter contained in the plating solution are interposed in the circulation piping  204 . 
         [0086]    A bottom plate  210  having therein a large number of plating solution passage holes is disposed in the bottom of the plating tank body  186 , whereby the interior of the plating tank body  186  is separated into an upper substrate processing chamber  214  and a lower plating solution distribution chamber  212 . A downwardly-extending shield plate  216  is mounted to the bottom plate  210 . 
         [0087]    Thus, in the plating tank  40  of this embodiment, the plating solution Q is introduced into the plating solution distribution chamber  212  of the plating tank body  186  by the actuation of the pump  202 , passes through the large number of plating solution passage holes of the bottom plate  210  and flows into the substrate processing chamber  214 , flows upwardly approximately parallel to the surface of the substrate W held by the substrate holder  26  and flow into the overflow tank  200 . The plating tank  40  is thus constructed so that the plating solution Q can be moved approximately parallel to the surface of the substrate W by actuating the pump  202  when carrying out plating. 
         [0088]    A disk-shaped anode  220 , conforming to the shape of the substrate W, is held by an anode holder  222  and is disposed in the plating tank body  186  in a vertical position. When the plating solution Q is filled into the plating tank body  186 , the anode  220  becomes immersed in the plating solution Q and faces the substrate W held by the substrate holder  26  and disposed at a predetermined position in the plating tank body  186 . Also in the plating tank body  186 , an electric field regulation plate  224  for regulating an electric field in the plating tank body  186  is disposed between the anode  220  and the substrate holder  26  disposed at a predetermined position in the plating tank body  186 . In this embodiment, the electric field regulation plate  224  is comprised of a cylindrical portion  226  and a rectangular flange portion  228 , and is made of polyvinyl chloride which is a dielectric material. The cylindrical portion  226  has such an opening size and axial length as to sufficiently regulate the extent of electric field. The lower end of the flange portion  228  of the electric field regulation plate  224  reaches the bottom plate  210 . 
         [0089]    In the plating tank body  186 , between the electric field regulation plate  224  and the substrate W, held by the substrate holder  26  and disposed at a predetermined position in the plating tank body  186 , is disposed a vertically-extending stirring paddle  232  which reciprocates parallel to the substrate W to stir the plating solution Q between the substrate W and the electric field regulation plate  224 . By stirring the plating solution Q between the substrate W and the electric field regulation plate  224  by the stirring paddle  232 , ions in the plating solution Q can be supplied uniformly to the surface of the substrate W. 
         [0090]    As shown in  FIGS. 9 and 10 , the stirring paddle  232  is comprised of a rectangular plate-like member having a uniform thickness “t” of 3 mm to 5 mm, and has a plurality of parallel slits  232   a  that define vertically-extending strip-like portions  232   b . The stirring paddle  232  is formed of, for example, titanium with a Teflon coating. The vertical length L 1  of the stirring paddle  232  and the vertical length L 2  of the slits  232   a  are sufficiently larger than the vertical size of the substrate W. Further, the stirring paddle  232  is so designed that the sum of its lateral length H and its reciprocation distance (stroke) is sufficiently larger than the lateral size of the substrate W. 
         [0091]    It is preferred that the width and the number of the slits  232   a  be determined such that each strip-shaped portion  232   b  is as narrow as possible insofar as it has the necessary rigidity so that the strip-shaped portions  232   b  between the slits  232   a  can efficiently stir the plating solution and, in addition, the plating solution can efficiently pass through the slits  232   a.    
         [0092]    In this embodiment, as shown in  FIG. 10 , the slits  232   a  are formed vertically such that each strip-shaped portion  232   b  has a rectangular cross section. As shown in  FIG. 11A , each strip-shaped portion  232   b  may be chamfered at the four corners in its cross section or, as shown in  FIG. 11B , each strip-shaped portion  232   b  may be angled so that it has a parallelogram cross-sectional shape. 
         [0093]    As shown in  FIG. 12 , the stirring paddle  232  is secured to a horizontally-extending paddle shaft  238  by clamps  236  fixed to the upper end of the stirring paddle  232 . The paddle shaft  238  is held by shaft holders  240  and can slide horizontally. An end of the paddle shaft  238  is coupled to a paddle drive section  242  for reciprocating the stirring paddle  232  linearly and horizontally. The paddle drive section  242  converts the rotation of a motor  244  into the linear reciprocating movement of the paddle shaft  238  by a crank mechanism (not shown). In this embodiment, a control section  246 , which controls the movement velocity of the stirring paddle  232  by controlling the rotational speed of the motor  244  of the paddle drive section  242 , is provided. Instead of the paddle drive section  242  which uses the crank mechanism, it is also possible to use a paddle drive section which converts the rotation of a servo motor into the linear reciprocating movement of a paddle shaft by a ball screw, or a paddle drive section which linearly reciprocates a paddle shaft by a linear motor. A movement velocity of the stirring paddle  232 , for obtaining a sufficient stirring effect by the stirring paddle  232 , is preferably not less than 0.2 m/sec, more preferably not less than 0.5 m/sec. From the viewpoint of an apparatus design, the movement velocity of the stirring paddle  232  is not more than 2.0 m/sec. 
         [0094]    The magnetic film plating apparatus  110  is provided with a plating power source  250 ; the anode is connected to the anode  220  via a conducting wire, and the cathode is connected to the substrate W via a conducting wire during plating. 
         [0095]    In this embodiment, as shown in  FIG. 8 , a magnetic field generator  114  comprised of a cylindrical electromagnet  112  is disposed around the plating tank  40  including the plating tank body  186  and the overflow tank  200 . The electromagnet  112  is comprised of a cylindrical yoke  116  and a coil  118  extending circumferentially on an inner circumferential surface of the yoke  116 . By passing electric current through the coil  118 , the electromagnet  112  forms an upwardly directed magnetic field around and approximately parallel to a substrate held by the substrate holder  26 . The electromagnet  112  is coated with a resin resistant to a plating solution so that the electromagnet  112  will not be damaged by contact with the plating solution. 
         [0096]    As shown in  FIGS. 13A and 13B , a substrate holder receiver  120 , having an upwardly-open positioning recess  120   a , is mounted at a predetermined position in an upper surface of a surrounding wall of the plating tank  40 . By inserting the end of the hand  98  of the substrate holder  26  into the recess  120   a , the substrate holder  26  is supported and suspended vertically in the plating tank  40  while positioning the substrate holder  26  with respect to the plating tank  40 . A receiver contact terminal  124 , connected to a wire  122  extending from an external power source, is mounted at the bottom of the recess  120   a , while a holder contact terminal  126  is mounted to the end of the hand  98  at a position facing the receiver contact terminal  124 . The holder contact terminal  126  connects with the above-described conductor  88  via a wire  128 . When the hand  98  of the substrate holder  26  is inserted into the recess  120   a , the both contact terminals  124 ,  126  come into contact with each other to allow passage of electricity. 
         [0097]    To facilitate insertion of the hand  98  into the recess  120   a , the width of the recess  120   a  is somewhat larger than the width of the hand  98 . Therefore, in this embodiment, an air bag  130  is provided in one sidewall of the recess  120   a  of the substrate holder receiver  120 . After inserting the hand  98  into the recess  120   a , as shown in  FIG. 13A , the air bag  130  is expanded by a gas, such as air, as shown in  FIG. 13B , so that the air bag  130  presses the hand  98  against the other sidewall of the recess  120   a , thereby positioning the substrate holder  26  with respect to the plating tank  40 . When taking out the substrate holder  26 , the volume of the air bag  130  is reduced by sucking the gas from the air bag  130  by vacuum, or by opening the air bag  130  to the air. The use of the air bag  130  can prevent, without using a magnet which may disturb the magnetic field in the plating tank  40 , irregular movements of the substrate holder  26  caused by the pressure of the plating solution flowing by the movement of the stirring paddle  232 , thereby preventing poor contact between the contact terminals  124 ,  126 . It is also possible to use, e.g., an air cylinder or a motor instead of the air bag. 
         [0098]    In operation of the magnetic film plating apparatus  110 , a predetermined amount of plating solution Q having a predetermined composition is first filled into the plating tank body  186  and allowed to circulate. The substrate holder  26  holding a substrate W is lowered to dispose the substrate W at a predetermined position in the plating tank body  186  where the substrate W is immersed in the plating solution Q and held vertically. The anode of the plating power source  250  is connected to the anode  220  and the cathode is connected to the substrate W and, at the same time, electric current is passed through the coil  118  of the electromagnet  112 , thereby forming an upwardly directed magnetic field around and approximately parallel to the substrate W held by the substrate holder  26 . A plated film, a magnetic film (permalloy) having magnetic anisotropy, is allowed to grow on the surface of the substrate W while stirring the plating solution Q between the electric field regulation plate  224  and the substrate W by the stirring paddle  232 , as necessary, by moving the stirring paddle  232  parallel to the substrate W. By actuating the pump  202  of the circulation piping  204 , as necessary, during plating, the plating solution Q is circulated while keeping the plating solution Q at a predetermined temperature by cooling or heating it. After a predetermined time has elapsed from the start of plating, the anode  220  and the substrate W are disconnected from the plating power source  250 , and the supply of electric current to the coil  118  of the electromagnet  112  and the reciprocation of the stirring paddle  232  are stopped, thereby terminating plating. 
         [0099]    A sequence of process steps for plating of a magnetic film by the thus-constructed plating facility of this embodiment will now be described. First, substrates W having a surface seed layer as a feeding layer are placed with their front surfaces (surfaces to be plated) facing upwardly in a substrate cassette, and the substrate cassette is mounted in the loading/unloading port  18 . One substrate is taken by the substrate transport robot  20  out of the cassette mounted in the loading/unloading port  18 , and the substrate is place on the aligner  22  to align the direction of a notch portion or an orientation flat. After the alignment, the substrate is transported to the substrate attachment/detachment section  28  by the substrate transport robot  20 . 
         [0100]    In the substrate attachment/detachment section  28 , two substrate holders  26  housed in the stocker tanks  30  are simultaneously gripped by the substrate holder holding section  49  of the transporter  45  of the substrate transport apparatus  46  and the arm  48  is raised. The substrate holders  26  are then transported to the substrate attachment/detachment section  28 , where the arm  48  is rotated 90 degrees to bring the substrate holders  26  into a horizontal position. Thereafter, the arm  48  is lowered to simultaneously place the two substrate holders  26  on the loading plate of the substrate attachment/detachment section  28 , and then the cylinder is actuated to open the movable holding member  58  of the substrate holder  26 . 
         [0101]    In this state, the substrate, which has been transported by the substrate transport robot  20 , is inserted into the substrate holder  26  positioned on the center side, and the cylinder is reversely actuated to close the movable holding member  58 , and then the movable holding member  58  is locked by the locking/unlocking mechanism. Misalignment of the direction of the notch portion of the substrate W with respect to the substrate holder  26  upon this operation can be prevented by the first spring member  100  and the second spring member  102 , as shown in  FIGS. 7A through 7C . After completion of the attachment of the substrate to the one substrate holder  26 , the loading plate of the substrate attachment/detachment section  28  is slid laterally, and a substrate is attached to the other substrate holder  26  in the same manner. Thereafter, the loading plate is returned to the original position. 
         [0102]    Each substrate is thus fixed in each substrate holder  26  with its front surface (surface to be plated) exposed in the opening of the substrate holder  26  and its periphery sealed with the seal member  60  to prevent intrusion of a plating solution thereinto so as to allow electrical connection within the sealed portion, not in contact with the plating solution, with the plurality of electrical contacts  92 . The wire  128  from the conductors (electrical contacts)  88  is connected to the hand  98  of the substrate holder  26 . Therefore, electricity can be fed to the seed layer of the substrate by electrically connecting the contact terminals  124 ,  126 . 
         [0103]    Next, the two substrate holders  26  with the substrates attached thereto are simultaneously gripped by the substrate holder holding section  49  of the transporter  45  of the substrate transport apparatus  46  and the arm  48  is raised. The substrate holders  26  are then transported to the stocker tanks  30 , where the arm  48  is rotated 90 degrees to bring the substrate holders  26  into a vertical position. Thereafter, the arm  48  is lowered to simultaneously suspend the two substrate holders  26  in the stocker tanks  30  for temporary storage of the substrate holders  26 . The above operations are repeated sequentially to sequentially attach substrates to substrate holders  26 , which have been housed in the stocker tank  30 , and sequentially suspend the substrate holders  26  with the substrates attached in predetermined positions in the stocker tank  30  for their temporary storage. 
         [0104]    The two substrate holders  26  with the substrates attached thereto, which have been temporarily stored in the stocker tanks  30 , are simultaneously gripped by the substrate holder holding section  49  of the transporter  45  of the substrate transport apparatus  46  and the arm  48  is raised. The substrate holders  26  are then transported to the pre-wetting tanks  32 , where the arm  48  is lowered to immerse the substrate holders  26 , e.g., in pure water held in the pre-wetting tanks  32 , thereby wetting the surfaces of the substrates to enhance the hydrophilic properties. It is, of course, possible to use any aqueous liquid other than pure water insofar as the liquid can wet the surface of the substrate and replace air in holes with the liquid, thereby enhancing the hydrophilic properties of the substrate surface. 
         [0105]    A substrate holder  26  in which is housed a substrate whose electrical contact condition has been determined to be poor by a sensor, provided in the substrate holder  26 , for sensing contact between the substrate and the electrical contacts, is kept temporarily stored in the stocker tank  30 . This enables continuing plating operations without a stop of the apparatus despite the poor contact between the electrical contacts and the substrate attached to the substrate holder  26 . The substrate of poor electrical contact is not subjected to plating. In this case, after substrates are returned to the substrate cassette, the unplated substrate is removed from the substrate cassette. 
         [0106]    Next, in the same manner as described above, the two substrate holders  26  with the substrates attached thereto are transported to the pre-soaking tanks  34 , and the substrates are immersed in a liquid chemical, such as sulfuric acid or hydrochloric acid, held in the pre-soaking tanks  34  to etch away an oxide film, having a high electrical resistance, from the surface of the seed layer, thereby exposing a clean metal surface. Thereafter, in the same manner as described above, the substrate holders  26  with the substrates attached thereto are transported to the rinsing tanks  38 , and the substrate surfaces are rinsed (cleaned) with pure water held in the rinsing tanks  38 . 
         [0107]    In the same manner as described above, the two substrate holders  26  with the substrates after rinsing attached thereto are transported to the plating tanks  40  filled with a plating solution, and are each suspended and held at a predetermined position in each plating tank  40 . When the substrate is held in the plating tank  40 , as shown in  FIG. 13A , the end of the hand  98  of the substrate holder  26  is inserted into the recess  120   a  of the substrate holder receiver  120  of the plating tank  40 , and the contact terminals  124 ,  126  come into contact with each other, thereby allowing passage of electric current. Then, as shown in  FIG. 13B , the air bag  130  is expanded by a gas, such as air, so that the air bag  130  presses the hand  98  against the sidewall of the recess  120   a , thereby positioning the substrate holder  26  with respect to the plating tank  40 . Then, while supplying the plating solution into the plating tank  40  and allowing the plating solution to overflow into the overflow tank  200 , a plating voltage is applied between the anode  200  and the substrate and, at the same time, electric current is passed through the coil  118  of the electromagnet  112 , thereby forming an upwardly directed magnetic field around and approximately parallel to the substrate held by the substrate holder  26 . A magnetic film of permalloy, having magnetic anisotropy, is allowed to grow on the surface of the substrate while stirring the plating solution, as necessary, by moving the stirring paddle  232  parallel to the surface of the substrate by the paddle drive section  242 . 
         [0108]    After the completion of plating, the application of the plating voltage, the supply of the plating solution, the supply of electric current to the coil  118  of the electromagnet  112  and the reciprocation of the stirring paddle  232  are stopped. Thereafter, the two substrate holders  26  with the substrates after plating attached thereto are simultaneously gripped by the substrate holder holding section  49  of the transporter  45  of the substrate transport apparatus  46 , and the arm  48  is raised to withdraw the substrates from the plating solution Q in the plating tanks  40 . When thus withdrawing the substrate holders  26  from the plating solution Q in the plating tanks  40 , the tray  52  shown in  FIGS. 2 and 3  is moved from the retracted position to the position right under the substrate holders  26 , and then, in the same manner as described above, the substrate holders  26  are transported to the rinsing tanks  38 . Thus, the plating solution dropping from the substrate holders  26  is received by the tray  52 , thereby preventing the plating solution from falling, e.g., onto the magnetic field generator  114  using the electromagnet  112  or other devices lying outside the plating tanks  40 . 
         [0109]    After returning the tray  52  to the retracted position, the substrate holders  26  are lowered to immerse the substrates in pure water held in the rinsing tanks  38 , thereby rinsing (cleaning) the surfaces of the substrates with pure water. Thereafter, the substrate holders  26  with the substrates attached thereto are transported to the blow tanks  36  in the same manner as described above, where water droplets are removed from the substrate holders  26  by air blowing. Thereafter, the substrate holders  26  with the substrates attached thereto are returned to the stocker tanks  30  and are each suspended and held at a predetermined position in the stocker tank  30  in the same manner as described above. 
         [0110]    The two substrate holders  26  with the substrates after plating attached thereto, which have been returned to the stocker tanks  30 , are simultaneously gripped by transporter  45  of the substrate transport apparatus  46  and, in the same manner as described above, are placed on the loading plate of the substrate attachment/detachment section  28 . The substrate holder  26  in which is housed the substrate whose electrical contact condition has been determined to be poor by the sensor, provided in the substrate holder  26 , for sensing contact between the substrate and the electrical contacts, and which has been kept temporarily stored in the stocker tank  30 , is also transported and placed on the loading plate. 
         [0111]    The movable holding member  58  of the substrate holder  26  positioned on the center side is unlocked by the locking/unlocking mechanism, and the cylinder is actuated to open the movable holding member  58 . The substrate after plating is then taken by the substrate transport robot  20  out of the substrate holder  26 , and transported to the cleaning/drying device  24 , where the substrate is cleaned and then spin-dried by high-speed rotation of the cleaning/drying device  24 . The dried substrate is returned by the substrate transport robot  20  to the substrate cassette of the loading/unloading port  18 . 
         [0112]    After or in parallel with returning the substrate, which has been taken out of the one substrate holder  26 , to the substrate cassette, the loading plate of the substrate attachment/detachment section  28  is slid laterally and the other substrate is taken out of the other substrate holder  26 . The substrate is then treated in the same manner, and the spin-dried substrate is returned to the substrate cassette. 
         [0113]    After returning the loading plate of the substrate attachment/detachment section  28  to the original position, the two substrate holders  26 , from which the substrates have been taken out, are simultaneously gripped by the substrate holder holding section  49  of the transporter  45  of the substrate transport apparatus  46  and, in the same manner as described above, are returned to the predetermined positions in the stocker tanks  30 . Thereafter, two substrate holders  26 , which have been returned to the stocker tanks  30 , are simultaneously gripped by the substrate holder holding section  49  of the transporter  45  of the substrate transport apparatus  46  and, in the same manner as described above, are placed on the loading plate of the substrate attachment/detachment section  28 . Thereafter, the same operations as described above are repeated. 
         [0114]    As described hereinabove, according to the plating facility of this embodiment, by setting a substrate cassette, in which substrates are housed, in the loading/unloading port  18  and activating the apparatuses, electroplating using a dip method can be carried out in a fully automatic manner to form a magnetic film (plated film) of, e.g., permalloy, having magnetic anisotropy, on a surface of a substrate. 
         [0115]    By arranging a plurality of plating tanks  40 , each individually surrounded by the magnetic field generator  114  comprised of the electromagnet  112 , as in this embodiment, the formation of a magnetic field parallel to a substrate can be facilitated. 
         [0116]    In this embodiment, the magnetic field generator  114  is comprised of the cylindrical electromagnet  112  surrounding the circumference of the plating tank  40 . It is also possible to use a magnetic field generator  114   a , as shown in  FIG. 14 , comprised of a rectangular electromagnet  112  surrounding the circumference of the plating tank  40 . As shown in  FIG. 15 , it is also possible to arrange a plurality of plating tanks  40  (e.g., two tanks as shown), each including the plating tank body  186  and the overflow tank  200 , in parallel and to surround the plurality of plating tanks  40  with a single magnetic field generator  114   b  comprised of a rectangular electromagnet  112   b.    
         [0117]    When a common plating solution is used, it is possible to use a plating tank  40   a  including a plurality of plating tank bodies  186  disposed inside one overflow tank  200   a , as shown in  FIG. 16 , and to surround the circumference of the plating tank  40   a  with a magnetic field generator  114   c  comprised of an electromagnet  112   c.    
         [0118]    Though a magnetic field generator comprised of an electromagnet, which can adjust a magnetic force, e.g., in the range of 0 to 500 G (0 to 0.05 T), is used in the above embodiments, it is possible to use a magnetic field generator comprised of a permanent magnet. When a magnetic field generator comprised of a permanent magnet is used, the permanent magnet is disposed such that the N pole and the S pole line up vertically. 
         [0119]      FIG. 17  is a diagram illustrating the positional relationship between a substrate holder, a plating tank and a magnetic field generator in a magnetic film plating apparatus according to another embodiment of the present invention. In this embodiment is used a magnetic field generator  264  comprised of a pair of permanent magnets  262  mounted on a support  260  and disposed on opposite sides of a plating tank  40 . The magnetic field generator  264  forms a magnetic field around and parallel to a substrate W held by the substrate holder  26  and immersed in a vertical position in a plating solution Q. The magnetic field generator  264  may be comprised of an electromagnet, as described above. 
         [0120]      FIGS. 18 and 19  schematically show a magnetic film plating apparatus according to yet another embodiment of the present invention. The magnetic film plating apparatus  300  mainly comprises a vertically-movable substrate holder  26 , having the same construction as described above, for detachably holding and transporting a substrate W, a plating tank  302  and a magnetic field generator  306  comprised of a cylindrical electromagnet  304  disposed around the plating tank  302 . 
         [0121]    The plating tank  302  includes a plating tank body  308  for holding therein a certain amount of plating solution Q in which a substrate W, held by the substrate holder  26  with its peripheral portion watertightly sealed by the seal member  60  (see  FIGS. 7A through 7C ) and its front surface (surface to be plated) exposed, is to be immersed in a vertical position. An overflow tank  310  for receiving the plating solution Q that has overflowed the edge of the plating tank body  308  is provided around an upper portion of the plating tank body  308 . One end of circulation piping  314 , which is provided with a pump  312 , is connected to the bottom of the overflow tank  310 , and the other end of the circulation piping  314  is connected to the bottom of the plating tank body  308 . Thus, the plating solution Q corrected in the overflow tank  310  is returned into the plating tank body  308  by the actuation of the pump  312 . Located downstream of the pump  312 , a filter  316  for filtering out foreign matter contained in the plating solution is interposed in the circulation piping  314 . In the plating tank  302  of this embodiment, the plating solution Q flows upwardly approximately parallel to the surface of the substrate W held by the substrate holder  26  and flow into the overflow tank  310 . The circulation piping  314  may also be provided with a constant-temperature unit as in the above-described embodiment, and a degasifier for the plating solution. 
         [0122]    A disk-shaped anode  318 , conforming to the shape of the substrate W, and a first dummy anode  320  surrounding the circumference of the anode  318  are held by a first anode holder  322  and disposed in a vertical position in the plating tank body  308 . When the plating solution Q is filled into the plating tank body  308 , the anode  318  and the first dummy anode  320  become immersed in the plating solution Q and face the substrate W held by the substrate holder  26  and disposed at a predetermined position in the plating tank body  308 . Nickel (Ni), which is a ferromagnetic material, is used for the anode  318 . Instead of the nickel anode, it is also possible to use an insoluble anode (e.g., Ti coated with IrO 2  or Ti cladded with 1-μm Pt). 
         [0123]      FIGS. 20A and 20B  show the anode  318  and the first dummy anode  320 . As shown in  FIGS. 20A and 20B , in this embodiment, a rectangular anode material  322 , in its peripheral portion other than the central circular portion, is coated with a resin  324  to prevent deposition thereon from the plating solution; and the anode  318  is the portion not coated with the resin  324 , while the first dummy electrode  320  is the portion coated with the resin  324 . By thus constructing the anode  318  and the first dummy anode  320  integrally, formation of a gap between the anode  318  and the first dummy anode  320  can be prevented. As shown in  FIG. 21 , it is also possible construct the anode  318  and the first dummy anode  320 , which is entirely coated with the resin  324 , as separate members. This enables replacement of the first dummy anode  320 . 
         [0124]    In the plating tank body  308 , between the anode  318  and the substrate W, held by the substrate holder  26  and disposed at a predetermined position in the plating tank body  308 , is disposed a vertically-extending stirring paddle  232  having the same construction as described above, which reciprocates parallel to the substrate W to stir the plating solution Q between the substrate W and the anode  318 . By stirring the plating solution Q between the substrate W and the anode  318  by the stirring paddle  232 , ions in the plating solution Q can be supplied uniformly to the surface of the substrate W. As with the above-described embodiment, an electric field regulation plate may be disposed between the stirring paddle  232  and the anode  318 . 
         [0125]    The magnetic field generator  306  comprised of the electromagnet  304  is disposed outside the plating tank  302 . The electromagnet  304  comprises a cylindrical yoke  330  and a coil  332  extending circumferentially on the inner circumferential surface of the yoke  330 . The magnetic field generator  306  can form a vertical magnetic field parallel to and in the vicinity of the substrate Win the plating tank  302 , enabling the formation of a magnetic film, having magnetic anisotropy, on the substrate surface by electroplating. In this embodiment, the coil  332  is divided into an upper coil  332   a , a middle coil  332   b  and a lower coil  332   c . By passing independent electric currents through the respective coils  332   a ,  332   b  and  332   c , vertical magnetic fields of different strengths can be formed around vertically upper, middle and lower portions of the substrate W. 
         [0126]    In this embodiment, a desired magnetic field can be formed by controlling respective electric currents applied to the coils  332   a ,  332   b  and  332   c . For example, the magnetic field can be adjusted by, for example, changing the current applied to the middle coil  332   b  while keeping the currents applied to the upper coil  332   a  and the lower coil  332   c  constant. Though the three coils are used in this embodiment, any number of coils may be selected depending on the intended magnetic field, the size of the substrate, etc. 
         [0127]    By disposing the coil  332  inside the yoke  330 , leakage of magnetic field to the outside of the plating tank  302  can be suppressed. This enables a plurality of plating tanks  40  to be installed in adjacent positions. By making the vertical size of the electromagnet  304  used as the magnetic field generator  306  sufficiently larger than the size of the plating tank  302  and the size of the substrate W, a stable magnetic field can be formed around the substrate W in the plating tank  302 . As with the above-described embodiment, the electromagnet  332  comprised of the yoke  330  and the coil  332  is coated with a resin (not shown) resistant to a plating solution so that the electromagnet  304  will not be damaged if the plating solution splatters and adheres to the electromagnet  304 . 
         [0128]    As shown in  FIG. 19 , the substrate W held by the substrate holder  26  is disposed at the center of the electromagnet  304 , and the anode  318  is disposed opposite the surface (surface to be plated) of the substrate W. There is a slight possibility of deviation of magnetic field lines from a reference direction at a position spaced apart from the center of the electromagnet  304 . In addition, the magnetic field is basically formed symmetrically with respect to the center of the electromagnet  304 . Accordingly, disposing the substrate W at the center of the electromagnet  304  is most advantageous to the formation of a uniform magnetic field parallel to the surface of the substrate W. 
         [0129]    In this embodiment, a second dummy electrode  336 , having the same size as or similar size to the size of the sum of the anode  318  and the first dummy anode  320 , held by a second anode holder  336 , is disposed on the opposite side of the substrate W from the anode  318  and at the same distance from the substrate W as the distance of the anode  318  from the substrate W. Similarly to the above-described first dummy electrode  320 , the second dummy anode  336  comprises an anode material, for example nickel, which is entirely coated with a resin to prevent deposition thereon from a plating solution. 
         [0130]    In this embodiment, in order to form a vertical magnetic field parallel to the substrate W, the first dummy anode  318  and the second dummy anode  334  are disposed parallel to the substrate W and the anode  318 . If they are not parallel to each other, the direction of the magnetic field is unlikely to be uniform in the substrate surface. 
         [0131]    When a ferromagnetic material is used for the anode  318  and only the anode  318  is installed opposite the substrate W, magnetic field lines in the surface of the substrate W are attracted toward the anode  318 . Accordingly, the magnetic flux density in the surface of the substrate W decreases and variation in the magnetic flux density in the substrate surface becomes larger, resulting in increased deviation of the direction of the magnetic field lines from the reference direction (vertical direction). By disposing the substrate W at the center of the electromagnet  304  and between the anode  318  and the second dummy anode  334 , inclination of the magnetic field lines from the vertical direction toward the normal direction of the substrate W can be reduced. 
         [0132]    A region, in which magnetic field lines are curved, can be shifted away from the substrate W and the direction of magnetic field lines in the vicinity of the substrate W can be made closer to the reference direction by using the first dummy anode  320  having a larger size. The first dummy anode  320  is at a right angle to the reference direction of the magnetic flux. Accordingly, the use of the first dummy anode  320  in a rectangular shape, as compared to a circular shape, can make magnetic field lines in the vicinity of the substrate closer to the reference direction. 
         [0133]    For example, when a substrate W having a diameter of 300 mm is used, an anode  318  whose diameter is somewhat smaller than 300 mm is used. The circumference of the anode  318  is surrounded by a square first dummy anode  320  whose each side has a length of, e.g., 390 mm. On the opposite side of the substrate from the first dummy anode  320  is installed a second dummy anode  334 , having the same square shape as the first dummy anode  320 , such that the distance between it and the substrate is equal to the distance between the anode  318 /the first dummy anode  320  and the substrate. The dummy anodes  320 ,  334  may not be of a square shape. The thicknesses of the anode  318  and the dummy anodes  320 ,  334  are equal. The smaller their thickness is, the lower is their effect of attracting magnetic field lines. Therefore, their aspect ratio (diameter or length of each side/thickness) is preferably not less than 45. 
         [0134]    Though the anode  318  surrounded by the first dummy anode  320  and the second dummy anode  336  are disposed opposite each other with the substrate W interposed therebetween in this embodiment, it is also possible to dispose only the anode  318 , surrounded by the first dummy anode  320 , opposite the substrate W without providing the second dummy anode  336 . This can also reduce deviation of the magnetic flux in the substrate surface from the reference direction. 
         [0135]    When designing the direction of a substrate, the direction of a magnetic field and the direction of the flow of a plating solution in a plating apparatus that generates a magnetic field parallel to a substrate, the following three methods, as shown in  FIGS. 22A through 22C , may be considered: a method in which a substrate is held vertically, a magnetic field is formed in a vertical direction and a plating solution is allowed to flow upwardly, as shown in  FIG. 22A  (hereinafter referred to as “method A”); a method in which a substrate is held vertically, a magnetic field is formed horizontally and a plating solution is allowed to flow upwardly, as shown in  FIG. 22B  (hereinafter referred to as “method B”); and a method in which a substrate is held horizontally (with its surface to be plated facing downwardly), a magnetic field is formed horizontally and a plating solution is allowed to flow upwardly, as shown in  FIG. 22C  (hereinafter referred to as “method C”). The magnetic film plating apparatus  110  shown in  FIG. 8  and the magnetic film plating apparatus  300  shown in  FIGS. 18 and 19  employ the method A. A so-called cup method in which a substrate is bought into contact with a plating solution, which is caused to flow upwardly, is considered to correspond to the method C. 
         [0136]    The degree of freedom of the direction of a substrate will now be compared between the three methods. If the angle of a substrate around the X-axis deviates in the A method, the substrate will become non-parallel to the magnetic field. If the angle of the substrate around the Z-axis deviates, the direction of a structure formed on the substrate will deviate with respect to the direction of the magnetic field. On the other hand, even when the angle of the substrate around the Y-axis deviates to some degree, the magnetic field remains parallel to the flow of the plating solution. In view of the fact that it basically suffices if the substrate keeps parallel to an anode, it can be said that the direction of the substrate around the Y-axis has some degree of freedom. With reference to the method B, the direction of a substrate around the Y-axis and the direction around the Z-axis need to be set precisely for the same reasons. The substrate remains parallel to a magnetic field if the angle of the substrate around the X-axis deviates. The substrate, however, becomes non-parallel to the flow of plating solution, which can affect the in-plane uniformity of a plated film. With reference to the method C, the direction of a substrate around the X-axis and the direction around the Z-axis need to be set precisely for the above reasons. If the angle of the substrate around the Y-axis deviates, a plating solution will not hit the substrate uniformly, which may affect the in-plane uniformity of a plated film. In summary, the method B and the method C thus need three-axis adjustment, whereas the method A, which is employed by the magnetic film plating apparatus  110  shown in  FIG. 8  as well as the magnetic film plating apparatus  300  shown in  FIGS. 18 and 19 , only needs adjustment of the two axes and thus has a higher degree of freedom. This is a great advantage for a mechanism which transports a substrate, held by a substrate holder, in an apparatus. 
         [0137]    As shown in  FIG. 18 , in this embodiment, three coils, the upper coil  332   a , the middle coil  332   b  and the lower coil  332   c , are disposed in the height direction of the yoke  330 . The vertical position of the middle coil  332   b  is preferably equal to the vertical setting position of the substrate W. It is desirable that the upper coil  332   a  and the lower coil  332   c  be disposed at the same distance from the middle coil  332   b . Further, it is desirable that the center position of the yoke  330  in the height direction be equal to the vertical setting position of the substrate W. 
         [0138]    While the strength of a magnetic field cannot be adjusted when a permanent magnet is used as a magnetic field generator, the use of the electromagnet  304  can easily control the strength of a magnetic field. In this embodiment, the magnetic force can be controlled, e.g., in the range of 0 to 500 G (0 to 0.05 T). If necessary, the electromagnet  304  may be provided with a cooling mechanism. 
         [0139]    In this embodiment, as shown in  FIG. 23 , a paddle shaft insertion hole  330   a  for insertion of the paddle shaft  238  (see  FIG. 12 ) into the yoke  338  is provided at a position slightly below the upper coil  332   a  provided on an upper portion of the yoke  330  so that the paddle drive section  242  and the motor  244  (see  FIG. 12 ) are positioned outside the yoke  330 . Such construction can suppress the influence of the magnetic field formed by the electromagnet  304  on the motor  244  or on a transport device for use in transport of, e.g., a substrate holder. Further in this embodiment, a cylindrical portion  338  is provided at the inner opening end of the paddle shaft insertion hole  330   a  in order to minimize leakage of magnetic field to the exterior. 
         [0140]    In this embodiment, a plurality of exhaust ducts  340 , each penetrating an upper portion of the yoke  330  at a position slightly below the upper coil  332   a  and reaching an upper position in the plating tank  302 , are provided. By creating flows of air flowing from the plating tank  302  toward the exhaust ducts  340 , and discharging a vapor evaporating from the plating solution with the flows of air to the outside of the yoke  330 , contamination of a substrate with the vapor can be prevented. An arbitrary number of exhaust ducts may be provided. The air inlets of the exhaust ducts  340  are provided at upper positions in the plating tank  302  at which the inlets do not interfere with movements of the substrate holder  26 , the stirring paddle  232  (see  FIG. 12 ), etc. Though the exhaust ducts  340 , penetrating the yoke  330 , are provided at positions slightly below the upper coil  332   a  in this embodiment, exhaust ducts, penetrating the yoke  330  and communicating with the outside, may be provided at any positions, e.g., between the middle coil  332   b  and the lower coil  332   c.    
         [0141]    In operation of the magnetic film plating apparatus shown in  FIGS. 18 and 19 , similarly to the above-described magnetic film plating apparatus shown in  FIG. 8 , a predetermined amount of plating solution Q having a predetermined composition is first filled into the plating tank body  308  and allowed to circulate. The substrate holder  26  holding a substrate W is lowered to dispose the substrate W at a predetermined position in the plating tank body  308  where the substrate W is immersed in the plating solution Q and held vertically. The anode of a plating power source is connected to the anode  318  and the dummy anodes  320 ,  334  and the cathode is connected to the substrate W and, at the same time, electric current is passed through the upper coil  332   a , the middle coil  332   b  and the lower coil  332   c  of the electromagnet  302  independently, thereby forming an upwardly directed magnetic field around and approximately parallel to the substrate W held by the substrate holder  26 . A plated film, a magnetic film (permalloy) having magnetic anisotropy, is allowed to grow on the surface of the substrate W while stirring the plating solution Q between the anode  318  and the substrate W by the stirring paddle  232 , as necessary, by moving the stirring paddle  232  parallel to the substrate W. After a predetermined time has elapsed from the start of plating, the anode  318 , the dummy anodes  320 ,  334  and the substrate W are disconnected from the plating power source, and the supply of electric current to the upper coil  332   a , the middle coil  332   b  and the lower coil  332   c  of the electromagnet  302 , and the reciprocation of the stirring paddle  232  are stopped, thereby terminating plating. 
         [0142]    As described above, in the magnetic film plating apparatus shown in  FIG. 8  and the magnetic film plating apparatus shown in  FIGS. 18 and 19 , the angle of a substrate around the vertical axis is not restricted by the magnetic field; the substrate may face any direction insofar as the normal line of the substrate is horizontal. The angle of the substrate around the vertical axis is not restricted by the direction of the magnetic field insofar as the substrate makes a predetermined angle with respect to a plating tank and a structure inside the plating tank, such as an anode. This implies moderate restriction on designing or assembling of a plating facility, including a transport mechanism for transporting a substrate between processing tanks. 
         [0143]    While the present invention has been described with reference to the embodiments thereof, it will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described above, but it is intended to cover modifications within the inventive concept.