Method for manufacturing magnetic head device

Abstract

A method for manufacturing a magnetic head device that includes a soft magnetic layer includes the steps of forming a plating base layer in the soft magnetic layer through sputtering, and applying, during the forming step, a magnetic field in a direction parallel to an orientation fringe of a wafer in which the magnetic head device is formed.

Description

This application claims the right of foreign priority under 35 U.S.C. §119 based on Japanese Patent Application No. 2006-246633, filed on Sep. 12, 2006, which is hereby incorporated by reference herein in its entirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates generally to a magnetic head device manufacturing method, and more particularly to a method for manufacturing a magnetic head device including a soft magnetic layer, such as a shield layer. The present invention is suitable, for example, for a read head having a magnetoresistive device used for a hard disc drive (“HDD”).

Along with the recent widespread Internet, a magnetic disc drive that records a large amount of information including still and motion pictures has been increasingly demanded. When the surface recording density is increased so as to meet the large-capacity demand, the 1-bit area as a minimum unit of the magnetically recorded information on the recording medium reduces, and the signal magnetic field from the recording medium becomes weaker. In order to read this weak signal magnetic field, a small and sensitive read head is needed.

For this read head, a read head having a magnetoresistive device has been conventionally known. A typical magnetoresistive device provides a pair of gap layers between a pair of shield layers, and a magnetoresistive film between the pair of gap layers. The shield layers are formed through electroplating by forming a plating base layer through sputtering, sinking it into the electrolyte, and flowing the current through the plating base layer.

Prior art include, for example, Japanese Patent Application, Publication No. (“JP”) 5-73842.

The improved magnetic characteristics of the shield layers that shield the external magnetic field and one reflux magnetic domains shown in FIG. 7 are preferable in order to realize a highly sensitive read head. The parallel magnetic domains 2a and 2b in the longitudinal direction should be parallel and antiparallel to the predetermined direction. When it inclines to the predetermined direction, the abnormal magnetic domain occurs and deteriorates the magnetic characteristic.

When the magnetic head becomes smaller and the shield layer becomes thinner, a ratio of the plating base layer in the shield layer increases and the magnetic characteristic or magnetic anisotropy in the plating base layer greatly affects the magnetic characteristic of the magnetic head. On the other hand, JP 5-73842 improves the magnetic characteristic by executing the shield-layer forming step in the magnetic field (see paragraph no. 0014). In addition, this reference also proposes the heat treatment in the magnetic field after the plating layer is formed, so as to stabilize the magnetic anisotropy. However, JP 5-73842 is silent about the direction of the magnetic field in the film formation and the direction of the magnetic field in the heat treatment, and the magnetic domains 2a and 2b do not become parallel or antiparallel to the predetermined direction.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method of manufacturing a highly sensitive magnetic head device having a good shield characteristic.

A method according to one aspect of the present invention for manufacturing a magnetic head device that includes a soft magnetic layer includes the steps of forming a plating base layer in the soft magnetic layer through sputtering, and applying, during the forming step, a magnetic field in a direction parallel to an orientation fringe of a wafer in which the magnetic head device is formed. The plating base layer having superior magnetic anisotropy can be formed when the magnetic field is applied parallel to the orientation fringe. When the soft magnetic layer is a shield layer that shields the external magnetic field, the shield layer restrains scattering of the magnetic characteristic for each product, and has high stability to the heat and external magnetic field.

The method may further include the steps of forming the soft magnetic layer using the plating base layer through electroplating, and applying the magnetic field in the direction during the soft magnetic field forming step. Thereby, the plating layer having superior magnetic anisotropy can be formed. Preferably, the method includes the step of heat-treating the wafer in the magnetic field having the same direction as the direction. The deterioration of the magnetic characteristic due to the heat treatment can be prevented when the subsequent heat treatment maintains the magnetic field having the same direction as that of the film formation.

The method preferably further includes the step of applying the magnetic field to the wafer in a direction different from the direction at a room temperature, followed by the heat-treating step. The heat-treating step in the magnetic field provides a recovery from the deterioration of the magnetic characteristic due to the magnetic-field applying step at the room temperature. In that case, the heat-treating step may be performed at least once whenever the step of applying the magnetic field at the room temperature is performed plural times.

The method preferably includes the step of heat-treating the wafer in a nonmagnetic field, followed by the heat-treating step in the magnetic field. The heat-treating step in the magnetic field can provide a recovery from the deterioration of the magnetic characteristic due to the heat-treating step in the nonmagnetic field. In that case, the heat-treating step in the magnetic field may be performed at least once whenever the heat-treating step in the nonmagnetic field is performed plural times. In addition, the heat-treating step in the magnetic field has a temperature higher than that of the heat-treating step in the nonmagnetic field. Thereby, this configuration provides a recovery from the deterioration of the magnetic characteristic due to the heat treatment in the nonmagnetic field. The magnetic head device is, for example, a composite head device that includes a write head device and a read head device.

Other objects and further features of the present invention will become readily apparent from the following description of preferred embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an enlarged sectional view showing a structure of a magnetic head device, and FIG. 1B is an enlarged sectional view showing a structure of another magnetic head device.

FIG. 2 is a flowchart for explaining a method for manufacturing a magnetic head device according to one embodiment of the present invention.

FIG. 3 is a plane view for explaining a magnetic field applying direction.

FIG. 4 is a flowchart as a variation of FIG. 2.

FIG. 5A is a table showing a magnetic domain state of a magnetic head device manufactured by the manufacturing method of this embodiment. FIG. 5B is a graph of FIG. 5A.

FIG. 6A is a table showing a magnetic domain state of a magnetic head device manufactured by the conventional manufacturing method. FIG. 6B is a graph of FIG. 6A.

FIG. 7 is a schematic plane view of a reflux magnetic domain.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, a magnetic head device used for the HDD. The magnetic head device is a magnetoresistive/inductive composite head including an inductive head device for writing binary information into the magnetic disc using a magnetic field induced by a conductive coil pattern (not shown), and a magnetoresistive (“MR” hereinafter) head device for reading the resistance as binary information that varies according to a magnetic field generated by the magnetic disc.

The MR head device is applicable to both a type shown in FIG. 1A in which the sense current flows parallel to the lamination surfaces of the MR film, and a type shown in FIG. 1B in which the sense current flows perpendicular to the lamination surfaces of the MR film.

The inductive head device 130 is commonly used for both FIGS. 1A and 1B. The inductive head device 130 includes a nonmagnetic gap layer 132, an upper magnetic pole layer 134, an insulating film 136 made of an Al₂O₃ film, and an upper shield-upper electrode layer 139. As discussed later, the upper shield-upper electrode layer 139 also constitutes part of the MR head device 140.

The nonmagnetic gap layer 132 spreads over a surface of the upper shield-upper electrode layer 139, which will be described later, and is made, for example, of Al₂O₃. The upper magnetic pole layer 134 faces the upper shield-upper electrode layer 139 with respect to the nonmagnetic gap layer 132, and is made, for example, of NiFe. The insulating film 136 extends over a surface of the nonmagnetic gap layer 132, covers the upper magnetic pole layer 134, and forms the head-device built-in film 123. The upper magnetic pole layer 134 and upper shield-upper electrode layer 139 cooperatively form a magnetic core in the inductive write head device 130. A lower magnetic pole layer in the inductive write 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 flows between the upper magnetic pole layer 134 and upper shield-upper electrode layer 139 leaks from the floatation surface due to acts of the non-magnetic gap layer 132. The leaking magnetic-flux flow forms a signal magnetic field (or gap magnetic field).

The MR head device 140 shown in FIG. 1A includes the upper shield layer 139, a lower shield layer 142, an upper gap layer 144, a lower gap layer 146, a spin-valve film 150, and a lead terminal part 160.

The shield layers 139 and 142 are made, for example, of NiFe. The gap layers 144 and 146 are made of an insulating material, such as Al₂O₃. 139a and 142a denote plating base layers in the shield layers 139 and 142. Plating layers are formed on the plating base layers 139a and 142a and become the shield layers 139 and 142. The plating layer is formed by forming the plating base layer through sputtering, sinking the plating base layer in the electrolyte, and flowing the current through the plating base layer.

The spin-valve film 150 includes a free ferromagnetic layer 152, a nonmagnetic intermediate layer 154, a pinned magnetic layer 156, and an exchange-coupling layer 158, forming a GMR sensor. The spin-valve film 150 may have any types including a top-type spin-valve structure, a bottom-type spin-valve structure, and a dual spin valve structure.

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 the device width WE. Thus, the MR head device 140 shown in FIG. 1A is a CIP-GMR device having a CIP structure that applies the sense current parallel to the laminated surfaces of the spin-valve film 150 or perpendicular to the lamination direction. The hard bias layer 162 has a primary coat layer 163 made, for example, of Cr, CrTi alloy, and TiW alloy, and a hard ferromagnetic layer 164 made, for example, of such a magnetic material as CoPt alloy and CoCrPt alloy. The terminal layer 166 includes a primary coat layer 167 made of such a nonmagnetic layer as Ta, an electrode layer 167 made of gold, and a cap layer 169 made of Ta.

The MR head device 140A shown in FIG. 1B includes the upper shield layer 139, a lower shield layer 142, an upper gap layer 144, a lower gap layer 146, a MR film 150A, and a pair of hard bias films 160A arranged at both sides of the MR film 150A.

The MR film 150A is, for example, a TMR film, which includes, in order from the bottom in FIG. 1B, a free ferromagnetic layer 152A, a nonmagnetic insulating layer 154A, a pinned magnetic layer 156A, and an antiferromagnetic layer 158A. The TMR film has a ferromagnetic tunneling junction configured to hold the insulating layer 154 between the two ferromagnetic layers, and uses a tunneling phenomenon in which the electrons in the minus side ferromagnetic layer pass through the insulating layer to the plus side ferromagnetic layer, when the voltage is applied between the two ferromagnetic layers. The insulating layer 154A uses, for example, an Al₂O₃ film.

The MR film 150A may be a spin-valve film. In that case, the MR device is a CPP-GMR device, and includes, in order from the bottom shown in FIG. 1B, a free layer 152A, a nonmagnetic intermediate layer 154A, a pinned magnetic layer 156A, and an exchange-coupling (antiferromagnetic) layer 158A.

The hard bias film 160A generates a bias magnetic field that restrains noises. The hard bias film 160A is made, for example, of such a magnetic material as CoPt alloy and CoCrPt alloy.

Referring to now to FIGS. 2 and 3, a description will be given of the magnetic head device. Here, FIG. 2 is a flowchart for explaining the method of manufacturing the magnetic head device, and a manufacture of the upper shield layer 139 and subsequent layers will be mainly described. However, the manufacturing method of this embodiment is applicable to the other soft magnetic layer, such as the terminal layer using the plating base layer. First, the plating base layer is made of NiFe through sputtering (step 1002). In that case, as shown in FIG. 3, during sputtering, a magnetic filed is applied in a direction parallel to the orientation fringe OF of a wafer W in which the magnetic head devices are formed. The magnetic field is applied through a magnetic holder that combines a holder that holds the wafer W with a magnet. This inventor has discovered that the plating base layer has superior magnetic anisotropy by applying the magnetic field parallel to the orientation fringe as in the working example, which will be described later. Thereby, the shield layers 139 and 142 restrain scattering of the magnetic characteristic for each product, and have high stability to the heat and external magnetic field.

Next, the shield layer is formed through electroplating while a magnetic field is applied in a direction parallel to the orientation fringe OF shown in FIG. 3 (step 1004). Thereby, the plating layer having magnetic anisotropy can be formed. Next, the magnetic field is applied at the room temperature to the wafer W in a direction perpendicular to the orientation fringe OF (ρ-H) (step 1006). The step 1006 is a magnetic characteristic test, and applies the magnetic field in the direction perpendicular to the original direction. Thereafter, the wafer W is magnetized by applying the magnetic field in the direction parallel to the orientation fringe OF (step 1008). Thereafter, in order to confirm the magnetic characteristic, the wafer W is magnetized while the magnetic field is applied in a direction perpendicular to the orientation fringe OF (step 1010). Thereafter, the wafer W is heat-treated while the magnetic field is applied in the direction parallel to the orientation fringe OF (step 1012).

Next, resist coating, the alignment, and the development follow (step 1014). Thereafter, the wafer W is heat-treated in the magnetic field (hard bake) (step 1016). Thereafter, sputtering, the resist coating, the alignment, and the development follow (step 1018), and then the wafer W is heat-treated while the magnetic field is applied in the direction parallel to the orientation fringe OF (hard bake) (step 1020). Next, sputtering, the resist coat, the alignment, and the development follow (step 1022), and then the wafer W is heat-treated while the magnetic field is applied in the direction parallel to the orientation fringe OF (hard bake) (step 1024).

Next, resist coating, the alignment, and the development follow (step 1026), and then the wafer W is heat-treated while the magnetic field is applied in the direction parallel to the orientation fringe OF (hard bake) (step 1028). Next, the resist is coated (step 1030). Next, the magnetic field is applied at the room temperature to the wafer W in a direction perpendicular to the orientation fringe OF (ρ-H) for the magnetic characteristic test (step 1032). Thereafter, the wafer W is heat-treated while the magnetic field is applied in the direction parallel to the orientation fringe OF (step 1034). Thereafter, sorting and shipping follow (step 1036).

Steps 1006, 1010 and 1032 are the steps of applying the magnetic field at the room temperature to the wafer W in a direction different from the magnetic-field direction in the sputtering step, and have a fear for a deterioration of the shield characteristic. Subsequent to the step 1014 is the film formation step of each layer in the inductive head device 130. The steps 1012 and 1034 are the newly added steps. The steps 1016, 1020, 1024, and 1028 are the heat treatment steps that are performed in the magnetic field, whereas these steps have been conducted in the nonmagnetic field having a fear for a deterioration of the shield characteristic.

Thus, this embodiment has the heat treatment steps (i.e., the steps 1012, 1016, 1020, 1024, 1028, and 1034) that are performed for the wafer W in the magnetic field having the same direction as the magnetic field direction in the sputtering step 1002. The heat treatment at that time is preferably performed at the temperature as high as or higher than the normal heat temperature, such as 220° C. The “normal heat temperature” is the temperature of the above hard bake which has been conducted in the nonmagnetic field. The hard bake needs that temperature, because heating facilitates the magnetic-domain control. The heat treatment which has been conducted in the nonmagnetic field is performed in the magnetic field whose direction accords with the orientation fringe OF of the wafer W, and the deterioration of the magnetic characteristic of the shield layer can be prevented.

In addition, this embodiment provides the heat treatment step 1012 in the magnetic field once after the magnetic-field applying steps 1006 and 1010 at the room temperature are performed, but the step 1012 may be performed once for each of the magnetic-field applying steps 1006 and 1010 at the room temperature. Moreover, this embodiment provides the heat treatment steps 1012 and 1034 in the magnetic field for the magnetic-field applying steps 1006, 1010, and 1032 at the room temperature, but may provide only the heat treatment step 1034 in the magnetic field. In other words, the heat treatment step in the magnetic field may be provided at least once for plural magnetic-field applying steps at the room temperature. In that case, the magnetic characteristic can be recovered from the deterioration by making the temperature higher than the normal heat treatment temperature or making a time period longer than the normal heat treatment time period.

Referring now to FIG. 4, a description will be given of a variation of the manufacturing method of FIG. 2. Here, FIG. 4 is a flowchart of the variation of the manufacturing method shown in FIG. 2. Those steps in FIG. 4, which are the corresponding steps in FIG. 2, are designated by the same reference numerals, and a description thereof will be omitted.

This embodiment replaces the steps 1016, 1020, 1024, and 1028 shown in FIG. 2 with the conventional heat treatment (hard bake) steps in the nonmagnetic field (i.e., the steps 1040, 1044, 1048, and 1052), and add the heat treatment steps in the magnetic field (i.e., the steps 1042, 1046, 1050, and 1054). Preferably, the heat treatment is performed at the temperature as high as or higher than the normal heat treatment temperature, such as 220° C. The “normal heat treatment temperature” is the temperature of the above heat treatment steps in the nonmagnetic field (i.e., the steps 1040, 1044, 1048, and 1052) in this embodiment. This is because the temperature as high as or higher than the temperature is effective to the recovery from the deterioration of the magnetic characteristic due to the heat treatment in the nonmagnetic field. The magnetic field direction of the heat treatment in the magnetic field corresponding to the orientation fringe OF of the wafer W would prevent the deterioration of the magnetic characteristic of the shield layer due to the heat treatment.

In addition, this embodiment provides the heat treatment step in the magnetic field once after the heat treatment step in the nonmagnetic field, but it is sufficient to provide the heat treatment step in the magnetic field once after plural heat treatment steps in the nonmagnetic field. Therefore, only the step 1054 may be provided. In this case, as described above, the magnetic characteristic can be recovered from the deterioration by making the temperature higher than the normal heat treatment temperature or making the heat treatment time period longer than the normal heat treatment temperature time period.

WORKING EXAMPLE

According to the manufacturing method of this embodiment, two magnetic domains (ideal magnetic domains), three magnetic domains, and abnormal magnetic domains are observed after the plating base layer is sputtered while the magnetic field is applied parallel to the orientation fringe OF, after the heat treatment in the magnetic field, after the heat treatment in the nonmagnetic field, and after the reheat treatment in the magnetic field. In other words, this observation corresponds to an observation after each of the steps 1002, 1012, 1040, and 1042 shown in FIG. 6B. In general, {100%−(a ratio (%) of the two magnetic domains)+(a ratio (%) of the three magnetic domains)}=(a ratio (%) of the abnormal magnetic domains) is met, but four or more magnetic domains can exist. The two magnetic domains mean that there are two magnetic domains 2a and 2b parallel to the longitudinal direction, as shown in FIG. 7, in the reflux magnetic domain. On the other hand, the three magnetic domains mean that there are three magnetic domains. The abnormal magnetic domains mean that magnetic domains 2a and 2b parallel to the longitudinal direction incline to the orientation fringe OF. FIGS. 5A and 5B show the result. It is understood that the ratio of the abnormal magnetic domains is maintained 0% at each stage. It is also understood that the ideal, two magnetic domains is improved by the heat treatment in the magnetic field, and deteriorated in the heat treatment in the nonmagnetic field, but improved up to 97% in the reheat treatment in the magnetic field.

COMPARATIVE EXAMPLE

According to the conventional manufacturing method, two magnetic domains (ideal magnetic domains), three magnetic domains, and abnormal magnetic domains are observed after sputtering, after the heat treatment in the magnetic field, after the heat treatment in the nonmagnetic field, and after the reheat treatment in the magnetic field. In the comparative example, the plating base layer is sputtered in the nonmagnetic field, and the heat treatment in the magnetic field, and the reheat treatment in the magnetic field are added, which have never existed originally. FIGS. 6A and 6B show the result. It is understood that the ratios of the abnormal magnetic domain are 100%, 58%, 44%, and 61% at respective stages. In other words, it is understood that when the plating base layer is sputtered in the nonmagnetic field, the abnormal magnetic domains always remains even after it undergoes the heat treatment in the magnetic field.

Further, the present invention is not limited to these preferred embodiments, and various variations and modifications may be made without departing from the scope of the present invention.

Thus, the present invention can provide a method of manufacturing a highly sensitive magnetic head device having a good shield characteristic.

Claims

1. A method for manufacturing a magnetic head device that includes a soft magnetic layer, said method comprising the steps of:

forming a plating base layer in the soft magnetic layer through sputtering; and

applying, during said forming step, a magnetic field in a direction parallel to an orientation fringe of a wafer in which the magnetic head device is formed.

2. A method according to claim 1, wherein the soft magnetic layer is a shield layer that shields an external magnetic field.

3. A method according to claim 1, further comprising the steps of:

forming the soft magnetic layer using the plating base layer through electroplating; and

applying the magnetic field in the direction during said soft magnetic field forming step.

4. A method according to claim 1, further comprising the step of heat-treating the wafer in the magnetic field having the same direction as the direction.

5. A method according to claim 4, further comprising the step of applying the magnetic field to the wafer in a direction different from the direction at a room temperature, followed by said heat-treating step.

6. A method according to claim 5, wherein said heat-treating step is performed at least once whenever the step of applying the magnetic field at the room temperature is performed plural times.

7. A method according to claim 4, further comprising the step of heat-treating the wafer in a nonmagnetic field, followed by said heat-treating step in the magnetic field.

8. A method according to claim 7, wherein said heat-treating step in the magnetic field is performed at least once whenever said heat-treating step in the nonmagnetic field is performed plural times.

9. A method according to claim 7, wherein said heat-treating step in the magnetic field has a temperature higher than that of said heat-treating step in the nonmagnetic field.

10. A method according to claim 1, wherein the magnetic head device is a composite head device that includes a write head device and a read head device.