Abstract:
A method of plating, which allows compositions of plating patterns of a plurality of layers to be uniform without any operational complexity, is provided. The area of the plating layer electrodeposited including plating patterns is constant in each of the plurality of layers. Accordingly, a value of plating-current density is easily maintained constant without any special operation. Consequently, the plating patterns in each of the plurality of layers is easily formed to have an uniform composition.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method of plating suitable for forming plating patterns of a plurality of layers, and relates to a method of manufacturing a micro device suitable for manufacturing one that includes the plating patterns of the plurality of layers. 
         [0003]    2. Description of the Related Art 
         [0004]    In producing various sorts of electronic circuit boards and semiconductor device substrates, plating patterns, which are formed in the shape of plurality of layers and having the same composition with each other, may be formed on a limited portion of the substrate (object to be plated). When configurations (occupation area) of the plating patterns of the plurality of layers differ mutually, plating-current density needs to be adjusted in each of the plurality of layers in the plating in spite of using a plating bath of the same component. For example, the plating-current density is adjusted by controlling electrode area as shown in Japanese Laid-Open Patent Publication (Kokai) No. H11-1799, and Japanese Laid-Open Patent Publication (Kokai) No. H2-228493. 
       SUMMARY OF THE INVENTION 
       [0005]    However, operation is very complicated if every formation of the plating patterns needs adjustment of the plating-current density in each of the plurality of layers. Moreover, in spite of using a plating bath of the uniform component, compositions of the formed plating patterns tend to be quite different from each other in each layer. Since such composition difference affects the property value of the plating pattern itself, such as magnetic property, it is expected to be minimized to a maximum extent. 
         [0006]    The present invention has been devised in view of the above problem, and it is desirable to provide a method of plating, which allows the compositions of the plating patterns of a plurality of layers to be uniformed enough in each of the plurality of layers without any operational complexity. It is also desirable to provide a method of manufacturing a micro device that includes the plating patterns of a plurality of layers so that the compositions of the plating patterns may be uniformed enough in each of the plurality of layers without any operational complexity. 
         [0007]    A method of plating and a method of manufacturing a micro device includes a step of forming a plating layer including the plating pattern in each of plurality of layers so that an area of the plating layer electrodeposited is constant in each of the plurality of layers. Here, “the plating layer including the plating pattern” means that the plating layer includes not only the aimed plating pattern but also other portions. 
         [0008]    According to the method of plating and manufacturing the micro device of the present invention, the area of the plating layer electrodeposited is constant in each of the plurality of layers. As a result, plating-current density can be kept constant without any adjustment of plating current or electrode area. 
         [0009]    Preferably, the method of plating and the method of manufacturing the micro device includes steps of: forming a plating foundation layer in each of the plurality of layers, forming a resist frame and an auxiliary resist pattern on the plating foundation layer in each of the plurality of layers, forming the plating layer selectively on the plating foundation layer other than portions covered with the resist frame and the auxiliary resist pattern in each of the plurality of layers, removing the resist frame and the auxiliary resist pattern in each of the plurality of layers, and removing the plating layer other than the plating pattern surrounded by the resist frame in each of the plurality of layers, and sum total of the area of the resist frame and the auxiliary resist patterns in each of the plurality of layers is constant. Preferably, at least one of geometry and the area of the plating pattern differs between the plurality of layers. Preferably, in the formation process for each of the plurality of layers, a common plating bath is used for forming the plating layer in each of the plurality of layers. Further, it is desirable to form a plurality of the auxiliary resist patterns symmetrically with respect to the resist frame. Further, preferably, the resist frame and the auxiliary resist pattern are formed to have a line width equal to each other. The line width here means a width of, a cross section orthogonal to a longitudinally-extending direction (longitudinal direction) of each of the resist frame and the auxiliary resist pattern. 
         [0010]    According to the method of plating or method of manufacturing the micro device of the present invention, since the area of the plating layer electrodeposited, including the plating pattern, is made constant in each of the plurality of layers, the plating patterns, each having a composition uniformed enough in each of the plurality of layers, can be formed more easily, without changing any plating condition. 
         [0011]    Other and further objects, features and advantages of the invention will appear more fully from the following description. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a schematic sectional view showing a whole configuration of a plating device used for formation method of a layered film according to a first embodiment of the present invention. 
           [0013]      FIG. 2A  is a plan view and  FIG. 2B  is a partially enlarged view, each showing a configuration of a substrate appearing in  FIG. 1 . 
           [0014]      FIG. 3  is a sectional view showing a cross-sectional configuration of the layered film formed using the plating device appearing in  FIG. 1 . 
           [0015]      FIGS. 4A to 4C  are plan views showing a configuration of each plating pattern in the layered film shown in  FIG. 3 . 
           [0016]      FIG. 5  is a sectional view showing one production process of the layered film shown in  FIG. 3  using the plating device appearing in  FIG. 1 . 
           [0017]      FIG. 6  is a sectional view showing another production process subsequent to  FIG. 5 . 
           [0018]      FIG. 7  is a sectional view showing another production process subsequent to  FIG. 6 . 
           [0019]      FIG. 8  is a sectional view showing another production process subsequent to  FIG. 7 . 
           [0020]      FIGS. 9A to 9C  are plan views of a resist pattern shown in  FIG. 8 . 
           [0021]      FIG. 10  is a sectional view showing another production process subsequent to  FIG. 8 . 
           [0022]      FIG. 11  is a sectional view showing another production process subsequent to  FIG. 10 . 
           [0023]      FIG. 12  is a sectional view showing another production process subsequent to  FIG. 11 . 
           [0024]      FIG. 13  is a sectional view showing another production process subsequent to  FIG. 12 . 
           [0025]      FIG. 14  is a sectional view showing another production process subsequent to  FIG. 13 . 
           [0026]      FIG. 15  is a sectional view showing another production process subsequent to  FIG. 14 . 
           [0027]      FIGS. 16A to 16C  show a first modification with regard to a plan view configuration of the resist pattern shown in  FIG. 9 . 
           [0028]      FIGS. 17A to 17C  show a second modification with regard to the plan view configuration of the resist pattern shown in  FIG. 9 . 
           [0029]      FIGS. 18A to 18C  show a third modification with regard to the plan view configuration of the resist pattern shown in  FIG. 9 . 
           [0030]      FIGS. 19A to 19C  show a fourth modification with regard to the plan view configuration of the resist pattern shown in  FIG. 9 . 
           [0031]      FIGS. 20A to 20C  show a fifth modification with regard to the plan view configuration of the resist pattern shown in  FIG. 9 . 
           [0032]      FIG. 21  is an exploded perspective view showing a configuration of a thin film magnetic head, which is formed by a method of manufacturing the same according to a second embodiment of the present invention. 
           [0033]      FIG. 22  is a sectional view showing a configuration taken along the line XXI-XXI of the thin film magnetic head shown in  FIG. 21 , which is seen from the direction indicated by arrows. 
           [0034]      FIG. 23  is a plan view showing one production process in the method of manufacturing the thin film magnetic head shown in  FIG. 21 . 
           [0035]      FIG. 24  is a plan view showing another production process subsequent to  FIG. 23 . 
           [0036]      FIG. 25  is a sectional view showing another production process subsequent to  FIG. 24 . 
           [0037]      FIG. 26  is a plan view showing another production process subsequent to  FIG. 25 . 
           [0038]      FIG. 27  is a sixth modification with regard to the plan view configuration of the resist pattern shown in  FIG. 9 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0039]    Embodiments of the invention will be described in detail hereinbelow with reference to the drawings. 
       First Embodiment 
       [0040]    First, a plating device for implementing a formation method of a layered film as a first embodiment of the present invention, and an electrode assembly arranged therein will be described hereinbelow with reference to  FIGS. 1 to 4 . 
         [0041]      FIG. 1  is a schematic sectional view showing a configuration of the plating device. The plating device forms a plating layer on a surface  11 S (surface to be plated) of a substrate  11 , which is an object to be plated, and includes a plating liquid vessel  30  which contains a plating bath  31 , and a cathode electrode assembly  10  and an anode electrode assembly  20  disposed in the plating liquid vessel  30 , so as to be opposed to each other via the plating bath  31 . The cathode electrode assembly  10  is attached firmly to a bottom  32  of the plating liquid vessel  30  so that the plating bath  31  may not leak. The cathode electrode assembly  10  has an aperture  10 K, and the substrate  11  in the shape of a thin plate is disposed therein to cover the aperture  10 K. The substrate  11  is supported by a supporting body  50  which includes a stage  51  and a cylinder  52  so that the surface  11 S is in contact with the plating bath  31 . The plating bath  31  has a composition in accordance with a sort of plating layer to be obtained. The plating device further has a power unit  70 . The power unit  70  is electrically connected with the cathode electrode assembly  10  and the anode electrode assembly  20  by lead wires  71  and  72  respectively to apply direct current voltage between the electrodes. Although the power unit  70  of a type that applies direct current voltage is illustrated herein, it is not limited to this but what applies alternating voltage or pulse voltage can be used. 
         [0042]    The anode electrode assembly  20  includes an anode  21 , an anode cylinder  22  having the anode  21  attached to one end thereof, and a supporter  23  for fixing the other end of the anode cylinder  22  to an upper portion  33  of the plating liquid vessel  30 . The anode  21  is arranged so as to face with the surface  11 S via the plating bath  31 , and is connected with the power unit  70  by the lead wire  72  passing through the anode cylinder  22  and the supporter  23 . 
         [0043]    In this plating device, a plating seed layer covers the surface  11 S of the previously-formed substrate  11  to form the plating layer on the substrate, by applying direct current voltage between the cathode electrode assembly  10  and the anode electrode assembly  20  using the power unit  70 , when the plating liquid vessel  30  is filled with the plating bath  31  as shown in  FIG. 1 . 
         [0044]    Subsequently, the formation method of the layered film using this plating device will be explained with reference to  FIGS. 2 to 15 . 
         [0045]    Here, a case where layered film  1  (which will be described later) are formed on each of a plurality of element fields R 1  one-by-one on the substrate  11  as schematically shown in  FIGS. 2A and 2B , is explained for example. 
         [0046]      FIG. 2A  illustrates a whole configuration of the substrate  11 . In  FIG. 2A , each rectangular area R 3 , which is defined by dividing the substrate  11  into matrix, is equal to a range to be exposed by one operation of a stepper and so on (that is, an exposure region which can be exposed in one shot of the stepper), for example.  FIG. 2B  is an enlarged view of any one of the rectangular areas R 3 . The rectangular area R 3  includes a plurality of unit fields R 4  of a rectangular shape, that are defined by plurality of scribe lines L 1  and L 2 . Each unit field R 4  includes an element field R 1  and a gap field R 2  surrounding the element field R 1 . With such arrangement, the element fields R 1  are arranged in matrix and equally spaced at specified intervals. 
         [0047]    As shown in  FIG. 3 , the layered film  1  are formed by layering in order a first layer L 1  that includes a plating pattern M 1 , a second layer L 2  that includes a plating pattern M 2 , and a third layer L 3  that includes a plating pattern M 3 . Peripheries of the plating patterns M 1  to M 3  are surrounded by insulating layers Z 1  to Z 3 , respectively. The surfaces of the plating pattern M 1  and the insulating layer Z 1  form a coplanar face, the surfaces of the plating pattern M 2  and the insulating layer Z 2  form a coplanar face F 2 , and the surfaces of the plating pattern M 3  and the insulating layer Z 3  form a coplanar face F 3 . As shown in  FIGS. 4A to 4C  for example, the plating patterns M 1  to M 3  are all rectangular in plan view, but have different dimensions from each other. Namely, occupation areas of the plating patterns M 1  to M 3  are different from each other. However, they all have a similar composition.  FIG. 3  is a sectional view showing a layered structure of the layered film  1 , and  FIGS. 4A to 4C  are plan views showing configurations of the plating patterns M 1  to M 3  in plan view. Namely,  FIG. 3  corresponds to cross sections taking along the lines III-III of  FIGS. 4A to 4C . 
         [0048]    Formation process of the plating pattern M 1  is as follows. As first shown in  FIG. 5 , the substrate  11  is prepared as an object to be plated  4 . Then, as shown in  FIG. 6 , a plating foundation layer  12  is formed to completely cover the surface  11 S of the substrate  11 . The plating foundation layer  12  is formed with component materials such as nickel iron alloy (NiFe) by vacuum deposition method such as sputtering, for example. 
         [0049]    Subsequently, after forming a photoresist layer  13 Z so as to cover a surface of the plating foundation layer  12  completely, a photoresist pattern  13 A is formed using photolithographic technique, as shown in  FIG. 7 . Specifically, first, a latent image portion  13 K is formed by selectively exposing the photoresist layer  13 Z via a photo mask  14  which has an aperture  14 K of a specified shape. Subsequently, after performing heat-treatment as necessary, it is developed by dissolving and removing the latent image portion  13 K using a specified developer, and further, is washed and dried. In this manner, the photoresist pattern  13 A of a specified shape is completed. 
         [0050]    As shown in  FIG. 9  (A), photoresist patterns  13 B to  13 G, as an auxiliary pattern, are formed together with the formation of the photoresist pattern  13 A.  FIG. 9A  is plan view showing a planar configuration and layout of the photoresist patterns  13 A to  13 G (hereinafter generically called photoresist pattern  13 ). Namely,  FIG. 8  corresponds to a cross section taking along the line VIII-VIII of  FIG. 9A , seen from the direction indicated by an arrow. The photoresist pattern  13 A is disposed so as to surround a portion R 13 A in which the plating pattern M 1  will be formed (hereinafter called formation portion) Meanwhile, it is preferred that the other photoresist patterns  13 B to  13 G are disposed symmetrically with respect to the photoresist pattern  13 A so that the photoresist pattern  13 A may be centered. In this case, it is desirable that geometries and dimensions of each pair of the mutually-symmetrically disposed photoresist patterns of the photoresist patterns  13 B to  13 G are equal to each other, and a part of the photoresist patterns  13 B to  13 G is W 1 , which is equal to a part of the width of the photoresist pattern  13 A. Here, it is defined that an auxiliary portion R 13 B is an area excluding the portions occupied by the photoresist pattern  13  and the formation portion R 13 A from the unit field R 4 . Accordingly, sum total of the formation portion R 13 A and the auxiliary portion R 13 B are taken as an area to be plated, denoted by a plating portion R 13 . 
         [0051]    After forming the photoresist pattern  13 , plating is processed using the aforementioned plating device, and as shown in  FIG. 10 , a plating layer  15  made of NiFe is formed. The plating layer  15  is formed so as to occupy the plating portion R 13  shown in  FIG. 9A . At this time, the photoresist pattern  13 A works as a photoresist frame defining the outline of the plating pattern M 1 , which will be obtained eventually. 
         [0052]    After the formation of the plating layer  15 , the plating foundation layer  12  is partially exposed by removing the photoresist pattern  13  using an organic solvent as shown in  FIG. 11 . Further, an exposed portion R 12  of the plating foundation layer  12  is removed by milling or the like, using the plating layer  15  as an etching mask. In this manner, as shown in  FIG. 12 , the surface  11 S of the substrate  11  is partially exposed. 
         [0053]    Subsequently, after selectively forming a photoresist pattern  16  so as to cover the formation portion R 13  and the exposed surface  11 S as shown in  FIG. 13 , the plating layer  15  that is not covered by the photoresist pattern  16  is removed by wet etching as shown in  FIG. 14 . Finally, as shown in  FIG. 15 , the plating pattern M 1 , which is formed on the formation portion R 13  constituted by the plating layer  15  and the plating foundation layer  12 A, appears by removing the photoresist pattern  16  with an organic solvent or the like. 
         [0054]    Formation process of each plating patterns M 1 -M 3  is substantially the same. Namely, the process of forming the plating pattern M 2  on the plating pattern M 1  is as follows. First, an electrical insulating material such as aluminium oxide (Al 2 O 3 ) is formed in the state of  FIG. 15  so that the periphery of the plating pattern M 1  may be fully filled up, for example. Subsequently, flattening is performed until a surface of the plating pattern M 1  is exposed so that the coplanar face F 1  that is formed by the plating pattern M 1  and the insulating layer Z 1  is obtained. After this, the plating pattern M 2  is formed by repeating each formation process of  FIGS. 6 to 15 . Similarly, the plating pattern M 3  is layered on the coplanar face F 2  formed by the plating pattern M 2  and the insulating layer Z 2 , thereby completing the layered film  1  shown in  FIG. 3 . 
         [0055]    In forming each of the plating patterns M 1  to M 3 , one or more photoresist patterns are formed so that a total occupation area of each of the plating patterns may be equal to each other, and plating process is selectively performed using the same plating bath  31 . More specifically, in forming the plating pattern M 2 , photoresist patterns  17 B to  17 G are formed as an auxiliary pattern, together with the formation of a photoresist pattern  17 A, as shown in  FIG. 9B . The photoresist pattern  17 A is disposed so as to surround a portion R 17 A in which the plating pattern M 2  will be formed (hereinafter called as formation portion R 17 A), and works as a photoresist frame defining the outline of the plating pattern M 2 .  FIG. 9B  is a plan view showing a configuration of the photoresist patterns  17 A to  17 G (hereinafter generically called photoresist pattern  17 ) in plan view. Herein, sum total of the occupation areas of the photoresist pattern  17  is made equal to that of the photoresist pattern  13 . In other words, the occupation area of a plating portion R 17 , which is sum total of the formation portion R 17 A and an auxiliary portion R 17 B, is made equal to the occupation area of the plating portion R 13 . 
         [0056]    Also, the plating pattern M 3  is formed in a similar way. As shown in  FIG. 9C , photoresist patterns  18 B and  18 C as an auxiliary pattern are formed together with a photoresist pattern  18 A as a photoresist frame. The photoresist pattern  18 A is disposed so as to surround a portion (formation portion) R 18 A in which the plating pattern M 3  will be formed, and works as a photoresist frame defining the outline of the plating pattern M 3 .  FIG. 9C  is a plan view showing a configuration of the photoresist patterns  18 A to  18 C (hereinafter generically called photoresist pattern  18 ) in plan view. Herein, sum total of the occupation areas of the photoresist pattern  18  is made equal to that of the photoresist pattern  13 , and that of the photoresist pattern  17 , respectively. Namely, the occupation area of a plating portion R 18 , which is sum total of the formation portion R 18 A and an auxiliary portion R 18 B, is made equal to the occupation area of the plating portion R 13 , and the occupation area of the plating portion R 17 , respectively. 
         [0057]    As described above, in the present embodiment, since the sum total of the occupation areas of the photoresist pattern  13 , the sum total of the occupation areas of the photoresist pattern  17 , and the sum total of the occupation areas of the photoresist pattern  18  are all equal to each other, an area of each of the plating portions R 13 , R 17  and R 18 , used for the plating process of the plating patterns M 1  to M 3 , that is, an electrodeposition area, is always made equal to each other. Accordingly, plating-current density can be easily kept constant without changing a current value. As a result, the plating patterns M 1 -M 3  of an almost identical composition can be formed quite efficiently. In particular, difference in composition can be suppressed substantially when the auxiliary patterns such as the photoresist patterns  13 B to  13 G are arranged evenly around the photoresist frame such as the photoresist pattern  13 A. 
       &lt;Modification&gt; 
       [0058]    Layout of the photoresist patterns  13 ,  17  and  18  are not limited to those shown in  FIGS. 9A to 9C , and various modifications are available. Hereafter, some modifications of the present embodiment are shown. 
         [0059]    A first modification shown in  FIGS. 16A to 16C  is that the photoresist patterns  13  and  17  are respectively formed on the basis of the photoresist pattern  18 A, which defines the outline of the largest plating pattern M 3  so that sum totals of the occupation areas of the photoresist patterns  13  and  17  may be equal to the occupation area of the photoresist pattern  18 A, respectively. Namely, in forming the plating pattern M 3 , only the photoresist pattern  18 A working as a photoresist frame is formed, and formation of the other portions corresponding to the photoresist patterns  18 B and  18 C shown in  FIG. 9C  is omitted. On the other hand, in the cases of  FIGS. 16A and 16B , four photoresist patterns  13 B to  13 E (or  17 B to  17 E) are formed as an auxiliary pattern. Here, the photoresist patterns  13 B to  13 E are all identical in shape and dimension, and are arranged symmetrically with respect to the central photoresist-pattern  13 A as shown in  FIG. 16A . Similarly, the photoresist patterns  17 B to  17 E are all identical in shape and dimension, and are arranged symmetrically with respect to the central photoresist-pattern  17 A as shown in  FIG. 16B . 
         [0060]    In a second modification shown in  FIGS. 17A to 17C , the auxiliary pattern is provided in the gap field R 2  instead of the element field R 1 . Also in this case, the occupation area of the photoresist pattern  18 A is equal to sum total of the photoresist patterns  13 A to  13 E, and that of the photoresist patterns  17 A to  17 E, respectively. 
         [0061]    Similarly, in a third modification thereof shown in  FIGS. 18A to 18C , the auxiliary pattern is provided in the gap field R 2 . Also in this case, sum total of the occupation areas of the photoresist patterns  13 A to  13 K, that of the photoresist patterns  17 A to  17 G, and that of the photoresist patterns  18 A to  18 C, are all equal to each other. 
         [0062]    In a fourth modification shown in  FIGS. 19A to 19C  and a fifth modification shown in  FIG. 20A to 20C , the auxiliary pattern is provided in both of the element field R 1  and the gap field R 2 . Also in these cases, sum total of the occupation areas of the photoresist pattern  13 , that of the photoresist pattern  17 , and that of the photoresist pattern  18 , are all equal to each other. 
       Second Embodiment 
       [0063]    Subsequently, a thin film magnetic head and method of manufacturing the same will be described with reference to  FIGS. 21 to 26 , according to a second embodiment of the present invention. 
         [0064]    The thin film magnetic head of the second embodiment includes a plurality of plating patterns such as a lower shielding layer and an upper shielding layer, respectively formed in layers different from each other. First, a schematic configuration of the thin film magnetic head is explained hereinbelow, and detailed description of the shielding layers will be given later. 
         [0065]      FIG. 21  is an exploded perspective view showing a configuration of a thin film magnetic head  110  formed on one side of a slider in a magnetic head device.  FIG. 22  is a sectional view showing a configuration taken along the line XXI-XXI of  FIG. 21 , seen from the direction indicated by the arrow. As shown in  FIGS. 21 and 22 , the thin film magnetic head  110  is formed by layering a read head portion  110 A and a write head portion  110 B in order from a side close to a substrate  100  of the slider. The write head portion  110 B writes magnetic information on a magnetic recording medium, and the read head portion  110 A reproduces the magnetic information written on the magnetic recording medium. 
         [0066]    As shown in  FIGS. 21 and 22 , the read head portion  110 A is configured in such a manner that, on a side exposed to an air bearing surface (hereinafter called ABS)  100 F, a lower shielding layer  111 , a lower gap layer  112 , a magnetoresistive (hereinafter called MR) element  110 C, an upper gap layer  120  and an upper shielding layer  121  are layered in order on the substrate  100 , for example. 
         [0067]    The MR element  110 C includes a magnetoresistive film pattern (hereinafter called MR film pattern)  114 , a pair of magnetic domain controlling layers  115 L and  115 R extending on the both sides of the MR film pattern  114 , and a pair of conductive lead layers  116 L and  116 R formed on the pairs of magnetic domain controlling layers  115 L and  115  respectively. The MR film pattern  114  has a spin valve structure, which is typically configured in such a manner that a foundation layer, a pinning layer, a pinned layer, a non-magnetic layer, a free layer and a cap layer and so on are layered in order on the lower gap layer  112 . The MR film pattern  114  functions as a sensor for reading the information written on the magnetic recording medium. The pair of magnetic domain controlling layers  115 L and  115 R and the pair of conductive lead layers  116 L and  116 R are arranged so that they may be opposed to each other on both sides of the MR film pattern  114  along a direction corresponding to a direction of a write track width of the magnetic recording medium (that is, X-direction). The magnetic domain controlling layers  115 L and  115 R, which are typically formed by a hard magnetic material containing a cobalt platinum alloy (CoPt) or the like, arrange magnetic domain directions of free layers included in the MR film pattern  114  into a single domain so as to suppress generation of a Barkhausen noise. The conductive lead layers  116 L and  116 R, which are typically made of copper (Cu) or the like, work as a current path sending a sensing current to the MR film pattern  114  in a direction orthogonal to the layered direction (that is, X-direction), and, as shown in  FIG. 21 , are connected to electrodes  116 LP and  116 RP, respectively. 
         [0068]    The lower shielding layer  111  is typically made of a magnetic material such as a nickel iron alloy (NiFe), and works so that the MR film pattern  114  may not be affected by unnecessary magnetic field. The lower gap layer  112  is made of an electrical insulating material such as aluminium oxide (Al 2 O 3 ) and alumimium nitride (AlN), and is intended for electrical insulation between the lower shielding layer  111  and the MR film pattern  114 . Upper gap layer  120  is also made of an electrical insulating material as with the lower gap layer  112 , and is intended for electrical insulation between the upper shielding layer  121  and the MR film patterns  114 . The upper shielding layer  121  is made of a magnetic material such as a nickel iron alloy (NiFe) as with the lower shielding layer  111 , and works so that the MR film pattern  114  may not be affected by unnecessary magnetic field. The upper shielding layer  121  also works as a lower magnetic pole in the write head portion  110 B. It is to be noted that another lower magnetic pole may be provided separately from the upper shielding layer  121 . 
         [0069]    In the read head portion  110 A configured in this manner, a magnetization direction of the free layer of the MR film pattern  114  changes in accordance with a signal magnetic field applied from the magnetic recording medium. Accordingly, a magnetization direction of the pinned layer included in the MR film pattern  114  changes relatively. In this case, variation of magnetization directions is expressed by variation of electric resistance by sending the sensing current to the MR film pattern  114  via the pair of conductive lead layers  116 L and  116 R. With this, the signal magnetic field is detected to read magnetic information. 
         [0070]    The write head portion  110 B includes the upper shielding layer  121 , a write gap layer  141 , a pole chip  142 , a coil  143 , a photoresist layer  144 , a connecting portion  145  and an upper magnetic pole  146 , as shown in  FIGS. 21 and 22 . 
         [0071]    The write gap layer  141  is made of an electrical insulating material such as Al 2 O 3  and AlN, and is formed on the upper shielding layer  121 . The write gap layer  141  has an aperture  141 A for formation of a magnetic path in a position corresponding to the center of the coil  143  in the XY-plane (refer to  FIG. 21 ). The coil  143  is formed in the shape of a spiral in plan view around the aperture  141 A on the write gap layer  141 . Further, the photoresist layer  144  is formed in a specified pattern so as to cover the coil  143 . Here, the photoresist layer  144  has been cured in advance by heat-treatment. Terminals of the coil  143  are connected to electrodes  143 S and  143 E, respectively. The pole chip  142  is arranged between the coil  143  covered with the photoresist layer  144  on the write gap layer  141  and the ABS 100 F. The connecting portion  145  is arranged so as to cover the aperture  141 A. 
         [0072]    The upper magnetic pole  146 , which is made of a magnetic material having a high saturation magnetic flux density such as a NiFe alloy or iron nitride (FeN), is formed so as to cover the pole chip  142 , the photoresist layer  144  and the connecting portion  145 . The upper magnetic pole  146  connects the pole chip  142  and the connecting portion  145  magnetically, and further, is in contact with the upper shielding layer  121  via the connecting portion  145  to be magnetically connected therewith. Although not illustrated, it is to be noted that an overcoat layer made of Al 2 O 3  and so on covers the whole upper surface of the write head portion  110 B. 
         [0073]    The write head portion  110 B with such configuration writes information in such a manner as follows. Magnetic flux is generated by currents flowing through the coil  143  in the magnetic path constructed mainly by the upper shielding layer  121  and the upper magnetic pole  146 . The magnetic flux then produces a signal magnetic field around the write gap layer  141 , and the signal magnetic field magnetizes the magnetic recording medium to write information thereon. 
         [0074]    Next, method of manufacturing the thin film magnetic head  110  will be explained. 
         [0075]    First, whole picture of the method of manufacturing the thin film magnetic head  110  is explained with reference to  FIGS. 21 and 22 . 
         [0076]    First, after forming the lower shielding layer  111  which is typically made of NiFe by electroplating on the substrate  100 , the lower gap layer  112  is formed by sputtering or the like on the lower shielding layer  111 . Next, a multilayer film which will become the MR film pattern  114  is formed on the lower gap layer  112 . Specifically, the foundation layer, the pinning layer, the pinned layer, the non-magnetic layer, the free layer and the cap layer, all of which are not illustrated, are layered in order by sputtering or the like. Then, the multilayer film is selectively etched by photolithographical patterning, ion milling and the like, to form the MR film pattern  114 . After this, the pair of magnetic domain controlling layers  115 L and  115 R are formed on the lower gap layer  112  so that they may be opposed to each other on both sides of the MR film pattern  114 . Further, the conductive lead layers  116 L and  116 R are formed on the magnetic domain controlling layers  115 L and  115 R, respectively. Subsequently, the upper gap layer  120  is formed by sputtering for example so as to cover the whole body. Finally, the upper shielding layer  121 , which is typically made of NiFe, is selectively formed by electroplating on the upper gap layer  120 , and formation of the read head portion  110 A is generally completed. 
         [0077]    Subsequently, the write head portion  10 B is formed on the read head portion  110 A. 
         [0078]    Specifically, first, the write gap layer  141  is selectively formed on the upper shielding layer  121  by sputtering or the like, and is partially etched to form the aperture  141 A for forming the magnetic path. Next, the pole chip  142  is formed on the write gap layer  141  on the ABS 100 F side by electroplating, and the connecting portion  145  is formed by electroplating so that the aperture  141 A may be covered. Further, the coil  143  of a spiral shape is formed around the aperture  141 A, then the photoresist layer  144  is formed in a specified pattern so that the coil  143  may be covered, and is cured by heat-treatment. After forming the photoresist layer  144 , the upper magnetic pole  146  is selectively formed so as to connect the pole chip  142  and the connecting portion  145 . In this manner, formation of the write head portion  110 B is generally completed. 
         [0079]    Finally, the overcoat layer which is not illustrated is formed so as to cover all the foregoing structures including the upper magnetic pole  146 . In this manner, formation of the thin film magnetic head  110  which is constituted by the read head portion  110 A and the write head portion  110 B is completed. 
         [0080]    Subsequently, formation process of the lower shielding layer  111  and the upper shielding layer  121  is explained in detail with reference to  FIGS. 23 to 26 .  FIGS. 23 to 26  is a plan view showing each production process when the lower shielding layer  111  and the upper shielding layer  121  are formed. 
         [0081]    In forming the lower shielding layer  111 , s plating foundation layer (not shown) which is made of NiFe is formed so that a surface of the substrate  100  may be covered. Subsequently, after forming a resist layer (not shown) so that the whole plating foundation layer may be covered, a photoresist pattern  113 A of a specified shape as shown in  FIG. 23  is formed by photolithography. 
         [0082]    Photoresist patterns  113 B to  113 I, which are configured and arranged as shown in  FIG. 23 , are formed simultaneously with the formation of the photoresist pattern  113 A. The photoresist pattern  113 A as a photoresist frame is disposed so as to surround a portion R 113 A in which the lower shielding layer  111  will be formed (hereinafter called formation portion). The photoresist patterns  113 B to  113 I as an auxiliary pattern are desirably disposed symmetrically each other with respect to the photoresist pattern  113 A. In  FIG. 23 , the photoresist pattern  113 B vs. the photoresist pattern  113 I, the photoresist pattern  113 C vs. the photoresist pattern  113 H, the photoresist pattern  113 D vs. the photoresist pattern  113 G, and the photoresist pattern  113 E vs. the photoresist pattern  113 F are arranged symmetrically, respectively. It is further desirable that configurations and dimensions of the photoresist patterns  113 B to  113 I are all equal to each other, and a part of the width thereof is equal to a part of the width of the photoresist pattern  113 A. Here, it is defined that an auxiliary portion R 113 B is an area excluding the areas occupied by the photoresist pattern  113  (photoresist patterns  113 A to  113 I) and the formation portion R 113 A from the unit field R 4 . Accordingly, sum total of the formation portion R 113 A and the auxiliary portion R 113 B are taken as an area to be plated, denoted by the plating portion R 113 . 
         [0083]    After forming the photoresist pattern  113 , plating is performed using the foregoing plating device to form a plating layer (not shown) made of NiFe so that the plating portion R 113  may be occupied therewith. Then the lower shielding layer  111  of a specified shape, which is formed by the plating layer and the plating foundation layer and formed on the formation portion R 113 A, is obtained as with the above-mentioned first embodiment (refer to  FIG. 24 ). 
         [0084]    The upper shielding layer  121  can be formed as with the case of the lower shielding layer  111 . Namely, after forming a plating foundation layer (not shown) made of NiFe so that the surface of the upper gap layer  120  may be covered, photoresist patterns  117 A to  117 K (hereinafter generically called photoresist pattern  117 ) of a specified shape are arranged in a specified position as shown in  FIG. 25 . The photoresist pattern  117 A is disposed so as to surround a portion R 117 A in which the upper shielding layer  121  will be formed (formation portion), and works as a photoresist frame for defining the outline of the upper shielding layer  121 . On the other hand, photoresist patterns  117 B to  117 K works as an auxiliary pattern. After forming the photoresist pattern  117 , the upper shielding layer  121  of the specified shape, which is formed by the plating layer and the plating foundation layer and formed in the formation portion R 117 A, is obtained as with the case of the lower shielding layer  111  (refer to  FIG. 26 ). 
         [0085]    Here, it is defined that an auxiliary portion R 117 B is an area excluding the areas occupied by the photoresist pattern  117  and the formation portion R 117 A from the unit field R 4 . Herein, sum total occupation area of the photoresist pattern  117  is made equal to that of the photoresist pattern  113 ; In other words, the occupation area of a plating portion R 117 , which is the sum total of the formation portion R 117 A and the auxiliary portion R 117 B, is made equal to the occupation area of the plating portion R 113 . 
         [0086]    In the second embodiment of the present invention, as described above, since sum total of the occupation area of the photoresist pattern  113  and that of the photoresist pattern  117  are equal to each other, an electrodeposition area, which is an area to be plated with plating layer, is also equal in each layer of the thin film magnetic head. Accordingly, a value of plating-current density can be kept constant easily without changing a current value. As a result, the lower shielding layer  111  and the upper shielding layer  121 , which have an almost same composition each other, can be formed very efficiently. 
       FIRST EXAMPLE 
       [0087]    A detailed example of the present invention will be explained hereinbelow. 
         [0088]    In the following example (a first example) of the present invention, a layered film was produced by plating technique with use of a photoresist pattern corresponding to that shown in the fifth modification ( FIGS. 20A to 20C ) of the above-mentioned first embodiment. 
         [0089]    Specifically, the plating patterns M 1  to M 3  made of NiFe were respectively formed to have an average thickness of 2 μm respectively, in a specified region R 1  of 900 μm×400 μm on a silicon substrate (plated substrate) of 6 inches in diameter. Plane sizes of the plating patterns M 1  to M 3  will be indicated later in Table 1. Width of each gap field R 2  was 200 μm. The plating foundation layer  12  was formed to have an average thickness of 0.03 μm by sputtering. In forming the photoresist layer, “AZ5105P” of AZ Electronic Materials&#39; product was used as a photoresist material and applied, then was heat-treated for 90 seconds at 100 degrees C. Further, the latent image portion was formed using “NSR-EX  14 C (DUV)”, an exposure product of NIKON CORP. The exposing condition was set to: numerical aperture (NA): 0.6, diaphragm σ(ratio of illumination to lens NA): 0.6. After exposure, development was accomplished using an aqueous alkaline solution (2.38% aqueous tetramethylammonium hydroxide (TMAH)). Width W 1  of each photoresist patterns  13 A,  17 A and  18 A as a photoresist frame was 20 μm. Surface ratio of each plating portion (R 13 , R 17 , R 18 ) to the unit field R 4  was set to 85.6% in each of the first to third layers L 1  to L 3 , as shown in Table 1. A Watts-type nickel (N 1 ) bath, added by iron ion, was used as the plating bath  31 . The unnecessary plating layer  15  formed in each of the auxiliary portions R 13 B, R 17 B, and R 18 B was removed by wet etching with use of a ferric chloride solution as etching solution. Further, each photoresist pattern was removed with use of acetone or N-methylpyrrolidone (NMP). 
         [0090]    Composition of the layered film, which was produced in the first example on the aforementioned condition, was confirmed in comparison with that of a first comparative example using a microscopic fluorescent-X-ray-spectrographic-analysis apparatus “JSM-6600F” of JEOL Co., Ltd. Here, the average content of nickel element in five arbitrary places was measured in each of the plating patterns M 1  to M 3 . Results are shown in Table 1 with manufacturing conditions. In addition, a case where layered film including the plurality of plating patterns were produced by plating only with use of the photoresist frame and without any auxiliary pattern at all, is shown as the first comparative example in Table 1. Set current of power supply was set to 2.8 A in the first example, and 3.0 A in the first comparative example. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Surface Ratio 
                   
               
               
                   
                   
                 Plane Size 
                 Width of 
                 of 
                 Ni Content 
               
               
                   
                   
                 of Plating 
                 Photoresist 
                 Metal-plated 
                 of Plating 
               
               
                   
                 Layers 
                 Pattern 
                 Frame 
                 Portion 
                 Pattern 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 1 
                 First 
                 50 μm × 50 μm 
                 20 μm 
                 85.6% 
                 81.5% 
               
               
                   
                 layer 
               
               
                   
                 Second 
                 50 μm × 100 μm 
                 20 μm 
                 85.6% 
                 81.5% 
               
               
                   
                 layer 
               
               
                   
                 Third 
                 50 μm × 150 μm 
                 20 μm 
                 85.6% 
                 81.5% 
               
               
                   
                 layer 
               
               
                 Comparative 
                 First 
                 50 μm × 50 μm 
                 20 μm 
                 91.7% 
                 81.5% 
               
               
                 Example 1 
                 layer 
               
               
                   
                 Second 
                 50 μm × 100 μm 
                 20 μm 
                 88.7% 
                 81.2% 
               
               
                   
                 layer 
               
               
                   
                 Third 
                 50 μm × 150 μm 
                 20 μm 
                 85.8% 
                 80.9% 
               
               
                   
                 layer 
               
               
                   
               
             
          
         
       
     
       FIRST EXAMPLE 
       [0091]    As shown by Table 1, it was confirmed that, in the case of the first comparative example, the nickel content decreased according to the reduction of the surface ratio of each of the Plating portions (electrodeposition areas). On the other hand, in the case of the first example, it was confirmed that the nickel content was equal in each of the Plating patterns (namely, the composition ratio of Ni to Fe was equal in each pattern) because surface ratio of the Plating portion (electrodeposition area) was uniformed in each of the first to the third layers. Thus, it proves that the plating method of the present invention is effective when the planar configuration and occupation area of the plating pattern is different in each layer. 
         [0092]    As mentioned above, although the present invention has been explained with reference to some embodiments and examples (hereinafter generically called embodiments), the present invention is not limited to the embodiments, and various kinds of modifications are available. For example, although the above-mentioned embodiments explain the cases where the plating patterns M 1  to M 3  are layered continuously, it is not limited to this. For example, an arbitrary intervening layer, which is formed by a method other than the electroplating method, such as sputtering, may be disposed therebetween. In that case, the intervening layer may be a plating layer or may be an insulating layer. Besides, in the above-mentioned embodiments, although one plating pattern is formed in each layer, a plurality of plating patterns may be formed collectively in each layer. For example, the present invention is also applicable to a case where a photoresist frame  19 A surrounding a formation portion R 19 A of a rectangular shape and a photoresist frame  19 B surrounding a formation portion R 19 B of an elliptical shape are formed in the same layer to collectively produce a plating pattern of the rectangular shape and a plating pattern of the elliptical shape with use of the photoresist frames  19 A and  19 B, as shown in a sixth modification shown in  FIG. 27 . 
         [0093]    Besides, in the above-mentioned embodiments, although the case is explained where the plating pattern of each layer is different from each other in configuration and dimension, it is not limited to this. For example, the present invention is also effective when only the configuration of the plating pattern mutually differs in each layer and the area thereof is all equal. Namely, when the plating pattern in each layer has a remarkably different configuration from each other, growing difference thereof may cause a considerable difference in the composition thereof even if the area of the plating pattern is equal to each other. In the present invention, even if the plating pattern in each layer has a different configuration from each other, difference in composition thereof can be suppressed very small by forming the layers so as to include other auxiliary plating layers thereon in addition to the plating patterns, respectively. 
         [0094]    In the second embodiment as described above, although the case of forming a plurality of magnetic shielding layers all having the same composition to be used in a thin film magnetic head is explained, the present invention is not limited to this. For example, it is also suitable for formation of various plating patterns included in other electronic and magnetic micro devices, such as a thin film inductor, a common mode filter or a magnetic random-access memory (MRAM). 
         [0095]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.