Abstract:
A method for manufacturing a magnetoresistive device that includes a spin-valve film, and a terminal layer that applies a sense current in a direction of a lamination surface in the spin-valve film, the spin-valve film including a pair of uncoupled ferromagnetic layers, and a non-magnetic metal layer that separates the pair of uncoupled ferromagnetic layers from each other, one of the ferromagnetic layers having a fixed direction of magnetization, and the other of the ferromagnetic layers having a freely variable direction of magnetization includes the steps of forming the terminal layer through sputtering, and preventing a formation of a sharp part on the terminal layer while interrupting the forming step.

Description:
[0001]    This application claims the right of a foreign priority based on Japanese Patent Application No. 2006-187058, filed on Jul. 6, 2006, which is hereby incorporated by reference herein in its entirety as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to a magnetoresistive device, and more particularly to a CIP-GMR sensor, which is a magnetic sensor that uses not only a spin-valve film that exhibits a giant magnetoresistive (“GMR”) effect, but also a current-in-plane (“CIP”) configuration that applies the sense current parallel to lamination surfaces in the spin-valve film. The present invention is suitable, for example, for a read head for use with a hard disc drive (“HDD”). 
         [0003]    Along with the recent spread of the Internet etc., magnetic disc drives that record a large amount of information including still and motion pictures have increasingly been demanded. As the surface recording density increases to meet the demand for the large capacity, a minimum unit of the magnetic recording information or a 1-bit area reduces on the recording medium, weakening a signal magnetic field obtained from the recording medium. A small, highly sensitive read head is necessary to read this weak signal magnetic field. 
         [0004]    A read head that utilizes a CPI-GMR sensor is conventionally known. See, for example, FIG. 1 of Japanese Patent Application, Publication No. 2001-229515. The CIP-GMR head includes a pair of gap layers between a pair of shield layers, and a spin-valve film between the pair of gap layers. A pair of lead terminal parts are provided at both ends of the spin-valve film, and each lead terminal part includes a terminal layer and a hard bias layer. The sense current is applied parallel to the lamination surface of the spin-valve film between both terminal layers. 
         [0005]    The highly sensitive read head needs to have an improved shield characteristic or external magnetic field resistance characteristic that shields the external magnetic field. However, the conventional upper shield layer has a set of plural reflex magnetic domains rather than one reflex magnetic domain, as shown in  FIG. 9B , causing an insufficient shield effect. According to this inventor&#39;s study of the cause, the upper shield layer  60  has undesirable sharp parts  62  and  64  on its side of a gap layer  50  as shown in  FIG. 9A . The sharp parts  62  and  64  are likely to form magnetic domain walls, causing longitudinal crack magnetic domains (or a pair of central descending arrows) shown in  FIG. 9B . Then, the external magnetic field resistance characteristic (shield characteristic) of the shield layer  60  deteriorates, and an output fluctuates in the MR head device. As the gap layer  50  becomes thinner, influence of a leakage flux LF on a spin-valve film  10  increases, lowering the output. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    Accordingly, it is an exemplified object of the present invention to provide a highly sensitive magnetoresistive device having an excellent shield characteristic, and a read head and storage having the same. 
         [0007]    A method according to one aspect of the present invention for manufacturing a magnetoresistive device that includes a spin-valve film, and a terminal layer that applies a sense current in a direction of a lamination surface in the spin-valve film, the spin-valve film including a pair of uncoupled ferromagnetic layers, and a non-magnetic metal layer that separates the pair of uncoupled ferromagnetic layers from each other, one of the ferromagnetic layers having a fixed direction of magnetization, and the other of the ferromagnetic layers having a freely variable direction of magnetization includes the steps of forming the terminal layer through sputtering, and preventing a formation of a sharp part on the terminal layer while interrupting the forming step. This manufacturing method executes the preventing step by interrupting the forming step, and prevents a formation of a sharp part from being formed on the terminal layer. Since it becomes difficult to remove a sharp part of the terminal layer after the forming step is completed, the preventing step is conducted in the middle of the forming step. A sharp part is removed from the shield layer that is laminated on the terminal layer when a sharp part is removed from the terminal layer, and the shield characteristic of the shield layer improves. 
         [0008]    The preventing step may include the step of removing, through ion milling, part of the terminal layer that is being formed, while interrupting the forming step, and the method may resume the forming step after the removing step. The part of the terminal layer may be an electrode layer, because the electrode layer is thickest in the terminal layer that includes a lamination of a primary coat, the electrode layer, and a cap layer, and thus can secure a sufficient margin. For example, the removing step may set an angle between an ion beam direction of the ion milling and the direction parallel to the lamination surface to be between a sputtering angle −5° inclusive and the sputtering angle +10° inclusive, the sputtering angle being an angle between a sputtering particle flying direction of the forming step and the direction parallel to the lamination surface. A removal of the sharp part becomes insufficient near the resist outside this range. The removing step may start when a layer of the part of the terminal layer has a thickness between a prospective thickness formed by the forming step −100 Å and the prospective thickness. The removing step may execute the ion milling until a layer of the part of the terminal layer has a thickness between half a prospective thickness formed by the forming step ±100 Å. In this range, the preventing step can secure a sufficient margin, and prevent a formation of the sharp part. The removing step may start the ion milling when the electrode layer of the terminal layer has a thickness between a prospective thickness formed by the forming step −100 Å and the prospective thickness. In this range, the preventing step can secure a sufficient margin, and prevent a formation of the sharp part. 
         [0009]    The preventing step may change a sputtering angle between a sputtering particle flying direction of the forming step and the direction parallel to the lamination surface in the middle of the forming step. Thereby, only a sputtering apparatus can prevent a formation of the sharp part on the terminal part without ion milling. The preventing step may set the sputtering angle greater than the sputtering angle of the forming step. For example, the sputtering angle changes between the sputtering angle of the forming step +5° inclusive and the sputtering angle of the forming step +15° inclusive. In this range, a formation of the sharp part can be prevented. Preferably, the preventing step starts when a layer of part of the terminal layer has a thickness between half a prospective thickness formed by the forming step ±100 Å. In this range, the preventing step can secure a sufficient margin, and prevent a formation of the sharp part. 
         [0010]    A magnetoresistive device according to another aspect of the present invention includes a spin-valve film that includes a pair of uncoupled ferromagnetic layers, and a non-magnetic metal layer that separates the pair of uncoupled ferromagnetic layers from each other, one of the ferromagnetic layers having a fixed direction of magnetization, and the other of the ferromagnetic layers having a freely changeable direction of magnetization, a lead terminal part that includes a terminal layer that applies a sense current in a direction of lamination surface in the spin-valve film, and a hard bias layer that generates a bias magnetic field, and a shield layer laminated on the spin-valve film and the lead terminal part, wherein the shield layer on a side of the terminal layer has a curved surface shape between a first surface that passes a center of the spin-valve film and is perpendicular to the lamination surface, and a second surface that is parallel to and closest to the first surface, the terminal layer having an approximately constant thickness on the second surface. The shield layer that has a curved surface shape on the terminal layer side and dispenses with the sharp part is likely to secure a reflux magnetic domain, and maintain a predetermined shield characteristic. 
         [0011]    The terminal layer may have a curved surface shape on a side of the shield layer. When the shape of the shield layer follows the shape of the terminal shape, a sharp part can be removed from the shield layer. The magnetoresistive device may further include a gap layer between the spin-valve film and a pair of terminal layers and the shield layer, the gap layer having a curved surface shape on a side of the shield layer. In this case, when the shape of the shield layer follows the shape of the terminal shape, a sharp part can be removed from both the gap layer and the shield layer. In addition, only the gap layer is made smooth, and the sharp part may be removed from the shield layer. 
         [0012]    A read head according to still another aspect of the present invention includes a magnetoresistive device manufactured by the above manufacturing method or the above magnetoresistive device, a member that supplies a sense current, and a member that reads a signal from an electric resistance of the magnetoresistive device which changes according to a signal magnetic field. This read head has an improved shield characteristic, provides a high sensitivity, and prevents a degradation of an output by reducing the leakage flux. A storage that includes a magnetic head part including the above read head and a write head, and a drive part that drives a magnetic record medium to be recorded and reproduced by the magnetic head part also constitutes another aspect of the present invention. 
         [0013]    Other objects and further features of the present invention will become readily apparent from the following description of the preferred embodiments with reference to accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a plane view showing an internal structure of a hard disc drive (“HDD”) according to one embodiment of the present invention. 
           [0015]      FIG. 2  is an enlarged plane view of a magnetic head part in the HDD shown in  FIG. 1 . 
           [0016]      FIG. 3  is an enlarged sectional view of a lamination structure of a head shown in  FIG. 2 . 
           [0017]      FIG. 4A  is a schematic, partially enlarged section of an MR head device shown in  FIG. 3 .  FIG. 4B  is a schematic view of a magnetic domain in an upper shield layer shown in  FIG. 4A . 
           [0018]      FIG. 5  is a flowchart for explaining a sharp part formation preventing method according to a first embodiment of the present invention. 
           [0019]      FIGS. 6A to 6C  are schematic sectional views of several states corresponding to the flowchart shown in  FIG. 5 . 
           [0020]      FIG. 7  is a flowchart for explaining a sharp part formation preventing method according to a second embodiment of the present invention. 
           [0021]      FIGS. 8A to 8C  are schematic sectional views of several states corresponding to the flowchart shown in  FIG. 7 . 
           [0022]      FIG. 9A  is a partially enlarged section of a conventional CPI-GMR sensor, and  FIG. 9B  is a schematic view of a magnetic domain of an upper shield layer shown in  FIG. 9A . 
           [0023]      FIG. 10A  is a schematic sectional view of a conventional lead terminal part when the sputtering ends.  FIG. 10B  is a schematic sectional view showing that part of the lead terminal part shown in  FIG. 10A  is removed by ion milling. 
           [0024]      FIG. 11A  is a schematic sectional view of a hard bias layer formed through sputtering.  FIG. 11B  is a schematic sectional view of a primary coat and an electrode layer laminated on the hard bias layer of the terminal layer through sputtering.  FIG. 11C  is a schematic sectional view of a cap layer laminated on the electrode layer through sputtering. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    Referring now to the accompanying drawings, a description will be given of an HDD  100  according to one embodiment of the present invention. The HDD  100  includes, as shown in  FIG. 1 , one or more magnetic discs  104  each serving as a recording medium, a spindle motor  106 , and a head stack assembly (“HAS”)  110  in a housing  102 . Here,  FIG. 1  is a schematic plane view of the internal structure of the HDD  100 . 
         [0026]    The housing  102  is made, for example, of aluminum die cast base, stainless steel, or the like, and has a rectangular parallelepiped shape to which a cover (not shown) that seals the internal space is joined. The magnetic disc  104  has a high surface recording density, such as 100 Gb/in 2  or greater. The magnetic disc  104  is mounted on a spindle (hub) of the spindle motor  106  through its center hole of the magnetic disc  104 . 
         [0027]    The spindle motor  106  has, for example, a brushless DC motor (not shown) and a spindle as its rotor part. For instance, two magnetic discs  104  are used in order of the disc, a spacer, the disc and a clamp stacked on the spindle, and fixed by bolts coupled with the spindle. 
         [0028]    The HSA  110  includes a magnetic head part  120 , a carriage  170 , a base plate  178 , and a suspension a carriage  179 . 
         [0029]    The magnetic head  120  includes a slider  121 , a head device built-in film  123  that is jointed with an air outflow end of the slider  121  and has a read/write head  122 . 
         [0030]    The slider  121  is made of an Al 2 O 3 —TiC (Altic), approximately rectangular parallelepiped, supports the head  122 , and floats over the surface of the rotating disc  104 . The head  122  records information into and reproduces the information from the disc  104 . A surface of the slider  121  opposing to the magnetic disc  104  serves as a floating surface  125 . Here,  FIG. 2  is an enlarged view of the magnetic head part  120 . 
         [0031]      FIG. 3  is an enlarged sectional view of the head  122 . The head  122  is, for example, a MR inductive composite head that includes an inductive head device  130  that writes binary information in the magnetic disc  104  utilizing the magnetic field generated by a conductive coil pattern (not shown), and a magnetoresistive (“MR”) head device  140  that reads the binary information based on the resistance that varies in accordance with the magnetic field applied by the magnetic disc  104 . 
         [0032]    The inductive head device  130  includes a non-magnetic gap layer  132 , an upper magnetic pole layer  134 , an insulating film  136  made of Al 2 O 3 , and an upper shield/upper electrode layer  139 . As discussed later, the upper shield/upper electrode layer  139  forms part of the MR head device  140 . 
         [0033]    The non-magnetic gap layer  132  spreads on a surface of the upper shield/upper electrode layer  139 , and is made, for example, of Al 2 O 3 . The upper magnetic pole layer  134  is provided opposite to the upper shield/upper electrode layer  139  with respect to the non-magnetic gap layer  132 , and is made, for example, of NiFe. The insulating film  136  covers the upper magnetic pole layer  134  on a surface of the non-magnetic gap layer  132 , and forms the head-device built-in film  123 . The insulating film  136  is made, for example, of Al 2 O 3 . The upper magnetic pole layer  134  and upper shield/upper electrode layer  139  cooperatively form a magnetic core in the inductive head device  130 . A lower magnetic pole layer in the inductive head device  130  serves as the upper shield-upper electrode layer  139  in the MR head device  140 . As the conductive coil pattern induces a magnetic field, a magnetic-flux flow between the upper magnetic pole layer  134  and upper shield/upper electrode layer  139  leaks from the floatation surface  125  due to acts of the non-magnetic gap layer  132 . The leaking magnetic-flux flow thus forms a signal magnetic field (or gap magnetic field). 
         [0034]    The MR head device  140  includes the upper shield/upper electrode layer  139 , a lower shield layer  142 , an upper gap layer  144 , and a lower gap layer  146 , a spin-valve film  150 , and a lead terminal part  160 . 
         [0035]    The shield layers  139  and  142  are made, for example, of NiFe. Thus, the gap layers  144  and  146  are made of an insulating member, such as Al 2 O 3 . 
         [0036]    The spin-valve film  150  includes a free ferromagnetic layer  152 , a non-magnetic intermediate layer  154 , a pinned magnetic layer  156 , and an exchange-coupling layer  158 , forming a GMR sensor. Usually, a non-magnetic layer is added, such as Ta, as a protective layer and a primary coat on the exchange-coupling layer  158  and under the free layer  152 . A type of the spin-valve film  150  is not limited irrespective of whether it is a top type spin valve, a bottom type spin valve, and a dual valve structure. 
         [0037]    The lead terminal part  160  has a hard bias layer  162  that generates a bias magnetic field, and a terminal layer  166  that applies the sense current and defines a device width WE. Thus, the MR head device  140  has a CIP structure that applies the sense current parallel to the lamination surface of the spin-valve film  150  or perpendicular to the lamination direction. The hard bias layer  162  includes, for example, a primary coat  163  that is made of Cr, CrTi alloy, TiW alloy, or the like, and has a thickness of about 50 Å, and a hard layer  164  that is made of such a magnetic material as CoPt alloy, CoCrPT alloy, or the like, and has a thickness of about 200 Å to 250 Å. The terminal layer  166  includes, for example, a primary coat  163  that is made of a non-magnetic layer such as Ta, and has a thickness of about 50 Å, and a cap layer  169  that is made of Ta and has a thickness of about 280 Å. 
         [0038]      FIG. 4A  is a schematic, partially enlarged section of the MR head device  140 , and  FIG. 4B  is a schematic view of a magnetic domain of the upper shield layer  139 . As shown in  FIG. 4A , portions  161   a  and  161   b  of the lead terminal part  160  which correspond conventional sharp parts have a smooth curved surface shape. The corresponding portions  144   a  and  144   b  of the upper gap layer  144  on the side of the upper shield layer  139  also have smooth curved surface shapes. The corresponding portions  139   a  and  139   b  of the upper shield layer  139  on the side of the lead terminal part  160  also have smooth curved surface shapes, dispensing with the conventional sharp parts. Thus, the upper shield layer  139  has a curved surface shape between a plane M that passes the center C of the spin-valve film  100  and is perpendicular to the horizontal direction (sense current application direction) and a plane P that is parallel to the plane M and closest to the plane M, the lead terminal part  160  having an approximately constant thickness on the plane P. 
         [0039]    The upper shield layer  139  has a smooth curved surface shape on the side of the lead terminal part  160 , and thus an amount of the leakage flux LF having starting points + and end points − in  FIG. 4A  is less than that shown in  FIG. 9A . Since the leakage flux LF shown in  FIG. 4A  is flatter, smoother, and thus weaker than that shown in  FIG. 9A . As a result, the leakage flux LF reduces in quantity and quality in  FIG. 4A . While the sharp parts  62  and  64  shown in  FIG. 9A  are likely to cause longitudinal crack magnetic domains,  FIG. 4A  removes the sharp parts and thus is likely to be maintain the reflux magnetic domain as shown in  FIG. 4B . As a result, the upper shield layer  139  can maintain the intended shield characteristic or external magnetic field resistance characteristic. The MR head device  140  can prevent an output depression through a reduction of the leakage flux LF. 
         [0040]    In order for the conventional upper shield layer  60  to realize a structure that makes smoother the upper shield layer  139  on the side of the lead terminal part  160  by removing the sharp part from the upper shield layer  139 , this inventor has addressed a shape of the lead terminal part  20 . As described later, the shapes of the upper gap layer  144  and the upper shield layer  139  follow the shape of the lead terminal part  160 . Thus, if the lead terminal part  20  is smooth and has no sharp part, as shown in  FIG. 4A , the upper shield layer  139  can be made smooth on the side of the lead terminal part  160 . Nevertheless, it is understood as shown in  FIG. 9B  that sharp parts  21  and  22  are formed on the conventional lead terminal part  20 . 
         [0041]    This inventor has first studied a removal of a sharp part formed on the lead terminal part  20  after sputtering of the lead terminal part  20  ends or a lamination formation ends.  FIG. 10A  is a schematic sectional view after sputtering of the lead terminal part  20  ends. Resist R is formed so as to prevent the lead terminal part  20  from being formed on the spin-valve film  100  when the lead terminal part  20  is sputtered. The resist R is removed after a formation of the lead terminal part  20  ends. The lead terminal part  20  has sharp parts  21  and  22 . 
         [0042]    In this state, as shown in  FIG. 10B , ion milling removes the sharp part  21  near the resist R and the sharp part  22  apart from the resist R. By rotating substrates (or elements  10  and  20 ), two angles A and B are set between an ion beam irradiating direction and a horizontal plane parallel to the sense current applying direction. The ion beam irradiating angle A is greater than the ion beam irradiating angle B. The A&#39;s ion milling can remove the entire surface of the lead terminal part  20 , but cause a reattachment of a film and burrs. The B&#39;s ion milling cannot remove the lead terminal part  20  near the resist R, and can remove only part apart from the resist R. After all, two sharp parts  23  and  24  and a dent  25  remain on a surface of the lead terminal part  20 , and thus the surface of the lead terminal part  20  does not become smooth. 
         [0043]    It is thus difficult to remove these sharp parts  21  and  22  from the lead terminal part  20  after sputtering of the lead terminal part  20  ends. One reason is a difficulty of introducing an ion beam into a very small interval between the resist R and the sharp part  21 . Accordingly, this inventor has studied a preventive measure of the sharp part formation during sputtering or a lamination formation of the lead terminal part  160 , because the interval between the resist R and the sharp part is enough large before the sputtering of the lead terminal part  160  ends. 
         [0044]    The manufacturing method of the lead terminal part  20  shown in  FIG. 10A  is initially studied.  FIG. 1A  is a schematic sectional view of the hard bias layer  30  formed in the lead terminal part  20  through sputtering. In  FIG. 11A , a solid line denotes the hard bias layer  30 , and a broken line denotes the lead terminal part  20  to be finally formed.  FIG. 11B  is a schematic sectional view of a primary coat  42  and an electrode layer  44  formed on the hard bias layer  30  in the terminal layer  40  through sputtering. In  FIG. 11B , a lower broken line denotes a boundary of the hard bias layer  30 , and a solid line denotes a boundary of the electrode layer  44  formed on the hard bias layer  30 . An upper broken line denotes the lead terminal part  20  to be finally formed.  FIG. 11C  shows a schematic sectional view of a cap layer  46  formed on the electrode layer  44  through sputtering. In  FIG. 11C , a solid line denotes the finally formed lead terminal part  20 . 
         [0045]    As a result of an analysis of  FIGS. 11A to 11C , this inventor has discovered that the following two methods can prevent a sharp part from being formed on the lead terminal part  20 : 
         [0046]    Referring now to  FIGS. 5 to 6C , a description will be given of a sharp part formation preventing method according to first embodiment of the present invention. Here,  FIG. 5  is a flowchart for explaining the preventive method of the first embodiment, and  FIGS. 6A to 6C  are schematic sectional views showing several states in this method. 
         [0047]    Referring to  FIG. 5 , the primary coat  163  is formed with a thickness of about 50 Å at a sputtering angle θ 1 =18° using Cr, CrTi alloy, TiW alloy or the like (step  1002 ). Next, the hard layer  164  is formed with a thickness of about 200 Å to 250 Å at a sputtering angle θ 1 =18° using CoCrPt alloy (step  1004 ). Next, the primary coat  167  is formed with a thickness of about 50 Å at a sputtering angle θ 1 =18° using Ta (step  1006 ). Next, the electrode layer  168  is formed with a thickness of about 600 Å at a sputtering angle θ 1 =25° using Au (step  1008 ).  FIG. 6A  shows this state. In  FIG. 6A , a solid line denotes a lamination member ( 162 + 167 + 168 ), and a broken line denotes the conventional lead terminal part  20  to be finally formed. 
         [0048]    Next, ion milling removes the electrode layer  168  by about 300 Å at an ion beam irradiation angle θ 2 =30° (step  1010 ).  FIG. 6B  shows this state. In  FIG. 6B , a solid line denotes a lamination member ( 162 + 167 + 168 ) (although the electrode layer  168  is scaled or scraped by half a prospective thickness to be formed), and a broken line denotes the lamination member ( 162 + 167 + 168 ) shown in  FIG. 6A . The prospective thickness of the electrode layer  168  is a thickness of the electrode layer  168  shown in  FIG. 3 , which is 600 Å. 
         [0049]    Next, the electrode layer  168  is formed by about 300 Å at a sputtering angle θ 3 =25° using Au (step  1012 ). Next, the cap layer  169  is formed with a thickness of about 280 Å at a sputtering angle θ 3 =25° using Ta (step  1014 ).  FIG. 6C  shows this state. In  FIG. 6C , a broken line denotes the lamination member ( 162 + 167 + 168 ) (although the electrode layer  168  is scaled or scraped by half a prospective thickness) shown in  FIG. 6B , and a solid line denotes the lead terminal part  160 . It is understood that a sharp part is removed from the lead terminal part  160  shown in  FIG. 6C , like  FIG. 4A . 
         [0050]    Then, the resist R is removed (step  1016 ), and the gap layer  144  is formed with a thickness of about 125 Å at a sputtering angle of 90° using Al 2 O 3  (step  1018 ). Next, the shield layer  139  is formed with a thickness of about 1.4 μm at a sputtering angle of 90° using NiFe (step  1020 ). As shown in  FIG. 4A , the upper shield layer  139  is smooth on the side of the lead terminal part  160  after a formation of the lamination ends. Thus, sputtering particles adhere to the entire surface of the substrate at a sputtering angle of 90° in steps  1018  and  1020 , and the shapes of the gap layer  144  and the shield layer  139  follow the shape of the lead terminal part  160 . 
         [0051]    Referring now to  FIGS. 7 to 8C , a description will be given of a sharp part formation preventing method according to a second embodiment.  FIG. 7  is a flowchart for explaining the sharp part formation preventing method according to a second embodiment, and  FIGS. 8A to 8C  are schematic sectional views of several states of this method. 
         [0052]    Referring to  FIG. 7 , the primary coat  163  is formed with a thickness of about 50 Å at a sputtering angle θ 1 =18° using Cr, CrTi alloy, TiW alloy, or the like (step  1002 ). Next, the hard layer  164  is formed with a thickness of about 200 Å to 250 Å at a sputtering angle θ 1 =18° using CoCrPt alloy (step  1004 ). Next, the primary coat  167  is formed with a thickness of about 50 Å at a sputtering angle θ 1 =18° using Ta (step  1006 ). Next, the electrode layer  168  is formed with a thickness of about 300 Å at a sputtering angle θ 1 =25° using Au (step  1102 ).  FIG. 8A  shows this state. In  FIG. 8A , a solid line denotes a lamination member ( 162 + 167 + 168 ) (although the electrode layer  168  has half a prospective thickness). 
         [0053]    Next, the electrode layer  168  is formed with a thickness of about 300 Å at a sputtering angle θ 4 =35° using Au (step  1104 ).  FIG. 8B  shows this state. In  FIG. 8B , a solid line denotes a lamination member ( 162 + 167 + 168 ) (although the electrode layer  168  has the prospective thickness), and a broken line denotes the lamination member ( 162 + 167 + 168 ) shown in  FIG. 8A . 
         [0054]    Next, the cap layer  169  is formed with a thickness of about 280 Å at a sputtering angle θ 5 =35° using Ta (step  1104 ).  FIG. 8C  shows this state. In  FIG. 8C , a broken line denotes the lamination member ( 162 + 167 + 168 ) (although the electrode layer  168  has the prospective thickness) shown in  FIG. 8B , and a solid line denotes the lead terminal part  160 . It is understood that a sharp part is removed from the lead terminal part  160  shown in  FIG. 8C , like  FIG. 4A . 
         [0055]    Thereafter, the resist R is removed (step  1016 ), and the gap layer  144  is formed with a thickness of about 125 Å at a sputtering angle of 90° using Al 2 O 3  (step  1018 ). Next, the shield layer  139  is formed with a thickness of about 1.4 μm at a sputtering angle of 90° using NiFe (step  1020 ). As shown in  FIG. 4A , the upper shield layer  139  is smooth on the side of the lead terminal part  160  after a formation of the lamination ends. 
         [0056]    Thus, the sharp part formation preventing methods of the first and second embodiments execute the preventive step in the middle of the formation of the lead terminal part  160  or while the lead terminal part  160  is being formed. This is because it is difficult to remove the sharp part once the forming step of the lead terminal part  160  is completed, as described with reference to  FIG. 10B . Next, the sharp part formation preventing methods according to the first and second embodiments execute the preventive step in the middle of a formation of the electrode layer  168  or while the electrode layer  168  is being formed. The electrode layer  168  has a thickness of about 600 Å and is thickest in the lamination of the terminal layer  166  that includes the primary coat  167 , the electrode layer  168 , and the cap layer  169 , and thus a sufficient margin can be secured. Of course, the present invention allows the preventive step to be executed in another layer or plural layers in the lead terminal part  160  and the gap layer  144 . 
         [0057]    While the ion milling in the first embodiment (in the step  1010 ) sets an angle θ 2  between the ion beam irradiation direction and the horizontal direction to 30°, the present invention allows an angular range between the sputtering angle θ 1 =25°−5° inclusive and the sputtering angle θ 1 =25°+10° inclusive, with respect to the sputtering angle θ 1  between the horizontal direction and a sputtering particle flying direction of the step  1008  (lamination forming step). A sharp part removal near the resist R becomes insufficient outside this range. While the ion milling in the first embodiment (the step  1010 ) sets a removal amount by the ion milling to 300 Å, the present invention allows a removal amount range between 300 Å±100 Å by the ion milling, because a sufficient margin can be secured in this range to prevent a formation of the sharp part. While the ion milling in the first embodiment (the step  1010 ) starts the removal of the ion milling when a formation of the electrode layer  168  ends or when the prospective thickness of 600 Å is obtained, the present invention may start the ion milling when the electrode layer  168  has a thickness from 500 Å to 600 Å, or when the prospective thickness −100 Å is obtained. In this range, the preventive step can secure a sufficient margin and prevent a formation of the sharp part. 
         [0058]    The second embodiment changes a sputtering angle in the middle of a formation of the electrode layer  168  or while the electrode layer  168  is being formed, thereby preventing a formation of a sharp part on the lead terminal part  160  only using a sputtering apparatus, i.e., without ion milling. While the second embodiment changes the sputtering angle to 35°, the present invention allows an angular range between the sputtering angle θ 1  of the step  1102  (layer formation step) of 25°+5° inclusive and the sputtering angle θ 1 =25°+15° inclusive, i.e., between 30° and 40°. A sharp part removal near the resist R becomes insufficient outside this range. While the second embodiment starts the step  1104  when the electrode layer  168  has a thickness of half a prospective thickness or 300 Å in the step  1102 , the present invention allows the step  1104  to start when the thickness of the electrode layer  168  becomes the prospective thickness ±100 Å. In this range, the preventive step can secure a sufficient margin and prevent a formation of the sharp part. 
         [0059]    Turning back to  FIG. 1 , the carriage  170  serves to rotate the magnetic head part  120  in arrow directions shown in  FIG. 1  and includes a voice coil motor (not shown), a support shaft  174 , a flexible printed circuit board (“FPC”)  175 , and an arm  176 . 
         [0060]    The voice coil motor  174  has a flat coil between a pair of yokes. The flat coil opposes to a magnetic circuit (not shown) provided to the housing  102 , and the carriage  170  swings around the support shaft  174  in accordance with values of the current that flows through the flat coil. The magnetic circuit includes, for example, a permanent magnet fixed onto an iron plate fixed in the housing  102 , and a movable magnet fixed onto the carriage  170 . 
         [0061]    The support shaft  174  is inserted into a hollow cylinder in the carriage  170 , and extends perpendicular to the paper plane of  FIG. 1  in the housing  102 . The FPC  175  provides a wiring part with a control signal, a signal to be recorded in the disc  104 , and the power, and receives a signal reproduced from the disc  104 . 
         [0062]    The arm  176  is an aluminum rigid body, and has a perforation hole at its top. The suspension  179  is attached to the arm  176  via the perforation hole and the base plate  178 . 
         [0063]    The base plate  178  serves to attach the suspension  179  to the arm  176 , and includes a welded section and a dent. The welded portion is laser-welded with the suspension  179 , and the dent is swaged with the arm  176 . 
         [0064]    The suspension  179  serves to support the magnetic head part  120  and to apply an elastic force to the magnetic head part  120  against the magnetic disc  104 , and is, for example, a stainless steel suspension. This type of suspension has a flexure (also referred to as a gimbal spring or another name) which cantilevers the magnetic head part  120 , and a load beam (also referred to as a load arm or another name) which is connected to the base plate. The load beam has a spring part at its center so as to apply a sufficient compression force in a Z direction. The suspension  179  also supports the wiring part that is connected to the magnetic head part  120  via a lead etc. 
         [0065]    In operation of the HDD  100 , the spindle motor  106  rotates the disc  104 . The airflow associated with the rotation of the disc  104  is introduced between the disc  104  and slider  121 , forming a minute air film and thus generating the floating power. The suspension  179  applies an elastic compression force to the slider  121  in a direction opposing to the floating power. As a result, the balance occurs between the floating power and the elastic force. 
         [0066]    This balance spaces the magnetic head part  120  from the disc  104  by a constant distance. Next, the carriage  170  is rotated around the support shaft  174  for head  122 &#39;s seek for a target track on the disc  104 . In writing, data is received from the host (not shown) such as a PC through the interface, supplied to the inductive head device  130 , and written in a target track via the inductive head device  130 . In reading, the predetermined sense current is supplied to the MR head device  140 , which in turn reads desired information from the desired track on the disc  104 . Since the shield characteristic is maintained in the MR head device  140  and the output fluctuation is restrained, a signal can be read at high sensitivity. 
         [0067]    Further, the present invention is not limited to these preferred embodiments, and various modifications and variations may be made without departing from the spirit and scope of the present invention. For example, the present invention is applicable to a magnetic sensor (such as a magnetic potentiometer for detecting a displacement and an angle, a readout of a magnetic card, a recognition of paper money printed in magnetic ink, etc.) as well as a magnetic head. 
         [0068]    The present invention can provide a highly sensitive magnetoresistive device having an excellent shield characteristic, and a read head and storage having the same.