JP2007280526A - Method for manufacturing thin film magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin film magnetic head which surely prevents a drop in coil inductance in a high-frequency area without changing the shape and structure of an inductive head element and without applying an unnecessary stress to a magnetic pole or a york. <P>SOLUTION: The lower part magnetic pole layer of an inductive write head element is formed, and a write gap layer is formed on the lower part magnetic pole layer thus formed, and then a coil conductor and an insulating layer which insulates the coil conductor are formed on the write gap layer thus formed. Then, an upper part magnetic pole layer is formed on the formed insulating layer and write gap layer. After the upper part magnetic pole layer is formed, field annealing is applied while a magnetic field having a direction in parallel to a lamination surface and to a magnetic medium facing surface is applied, to form a protective layer after the field annealing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a thin film magnetic head including an inductive write head element.

  In a thin-film magnetic head equipped with an inductive write head element, the magnetic domain for writing and the magnetic domain of the yoke magnetically coupled to the magnetic pole become unstable, resulting in a decrease in coil inductance in the high frequency band (10 MHz or higher). In some cases, abnormal writing characteristics occurred.

  In order to stabilize the magnetic domains of the magnetic pole and the yoke in the inductive head element, the shape of the magnetic pole is devised to form a 180 ° domain wall in the core width direction (Patent Document 1), and a magnetic domain control layer that is elongated in the core width direction is provided. It has been proposed to form a 180 ° domain wall in the width direction (Patent Document 2).

JP-A-11-161912 JP 2000-331310 A

  However, any of the techniques proposed in these patent documents cannot be easily applied because the design of the inductive head element is necessary because the magnetic pole portion has a special shape or structure. .

  Therefore, the inventors of the present application tried to stabilize the magnetic domains of the magnetic pole and the yoke in the inductive write head element by performing heat treatment in a magnetic field when the completed thin film magnetic head was shipped. However, if heat treatment is performed in a magnetic field at the time of shipment, the protective layer (overcoat layer) of the thin-film magnetic head expands, so that stress is applied to the magnetic pole and the yoke, resulting in a disadvantage that the write characteristics are deteriorated.

  Accordingly, an object of the present invention is to provide a method of manufacturing a thin film magnetic head that can reliably prevent a decrease in coil inductance in a high frequency region without changing the shape and structure of the inductive head element.

  Another object of the present invention is to provide a method of manufacturing a thin film magnetic head that can reliably prevent a decrease in coil inductance in a high frequency region without applying unnecessary stress to magnetic poles and yokes.

  According to the present invention, the lower magnetic pole layer of the inductive write head element is formed, the write gap layer is formed on the formed lower magnetic pole layer, and the coil conductor and the insulating layer that insulates the coil conductor are formed on the formed write gap layer. And forming an upper magnetic pole layer on the formed insulating layer and write gap layer, and after forming the upper magnetic pole layer, annealing in a magnetic field in a state where a magnetic field in a direction parallel to the laminated surface and the magnetic medium facing surface is applied, A method of manufacturing a thin film magnetic head is provided in which a protective layer is formed after annealing in a magnetic field.

  After forming the top pole layer and before forming the protective layer, the number of magnetic domains in the magnetic pole and yoke is reduced by annealing in a magnetic field with a magnetic field applied in a direction parallel to the laminated surface and the magnetic medium facing surface. Thus, the magnetic anisotropy in the direction parallel to the magnetic medium facing surface is increased, and the magnetic permeability in the direction perpendicular to the magnetic medium facing surface is increased. As a result, a decrease in coil inductance in the high frequency region can be reliably prevented, and deterioration of write characteristics can be prevented. In addition, since the design change of the inductive write head element is unnecessary, the implementation is easy and the versatility is high. Furthermore, since annealing is performed in a magnetic field before the protective layer is formed, there is no possibility that unnecessary stress is applied to the magnetic pole and the yoke due to thermal expansion of the protective layer.

  It is preferable that the annealing in the magnetic field is a heating to a temperature below the Curie point of the soft magnetic material constituting the lower magnetic pole layer and the upper magnetic pole layer. In this case, the soft magnetic material is more preferably Sendust, Permalloy, or CoZrTa.

  It is also preferable that annealing in a magnetic field is performed by applying a magnetic field of 15,920 A / m (200 Oe) to 238,700 A / m (3,000 Oe) in a vacuum and heating to 150 to 250 ° C.

  It is also preferred that the magnetic field to be applied is a direct current (DC) magnetic field.

  It is also preferable to form a magnetoresistive effect (MR) read head element on a substrate and to form the above-described inductive write head element on the formed MR read head element.

  It is also preferred that the thin film magnetic head is a multi-channel thin film magnetic head comprising a plurality of MR read head elements and inductive write head elements.

  According to the present invention, the number of magnetic domains of the magnetic pole and the yoke is reduced, the magnetic anisotropy in the direction parallel to the magnetic medium facing surface is increased, and the magnetic permeability in the direction perpendicular to the magnetic medium facing surface is increased. As a result, a decrease in coil inductance in the high frequency region can be reliably prevented, and deterioration of write characteristics can be prevented. In addition, since the design change of the inductive write head element is unnecessary, the implementation is easy and the versatility is high. Furthermore, since annealing is performed in a magnetic field before the protective layer is formed, there is no possibility that unnecessary stress is applied to the magnetic pole and the yoke due to thermal expansion of the protective layer.

  FIG. 1 is a sectional view schematically showing a thin film magnetic head manufactured in one embodiment of the present invention, and FIG. 2 is a process plan schematically showing a part of a wafer manufacturing process of the thin film magnetic head in this embodiment. FIG. The present embodiment is a case of a multi-channel thin film magnetic head for an LTO (linear tape open) tape drive. Of course, the present invention is not limited to such a multi-channel thin film magnetic head, but can also be applied to a single channel thin film magnetic head for a magnetic disk drive.

In FIG. 1, 10 is a substrate made of Al—TiC or the like, 11 is a 1.0 μm-thick underlayer made of an insulating material such as Al ₂ O ₃ (alumina) laminated on the substrate 10, and 12 is on the underlayer 11. For example, a lower shield layer having a thickness of 2.00 ± 0.30 μm, for example, made of a soft magnetic material such as Sendust or NiFe (permalloy), and 13 and 14 are, for example, alumina, SiO ₂ (oxidized) laminated on the lower shield layer 12. The lower and upper shield gap layers having a thickness of, for example, 100.0 nm made of an insulating material such as silicon) are formed between the lower and upper shield gap layers 13 and 14 at a portion close to the magnetic tape facing surface (TBS). The layer 16 is, for example, 2.0 ± 0 made of a soft magnetic material such as Sendust or Permalloy laminated on the upper shield gap layer 14. An upper shield layer having a thickness of 3 μm, an intermediate nonmagnetic layer 17 having a thickness of, for example, 0.020 ± 0.002 nm made of a nonmagnetic material such as Ta (tantalum) formed on the upper shield layer 16, and an intermediate nonmagnetic layer 18. For example, a lower magnetic pole layer having a thickness of, for example, 3.5 ± 0.3 μm made of a soft magnetic material such as high coercive force (HiBs), such as Sendust, Permalloy, or CoZrTa, is formed on the lower magnetic pole layer 18. For example, a write gap layer having a thickness of 0.45 μm made of an insulating material such as alumina, for example, 20 is a two-stage coil conductor made of a conductive material such as copper formed on the write gap layer 19, and 21 is a resist surrounding the coil conductor 20, for example A coil insulating layer 22 made of a material is formed on the write gap layer 19 and the coil insulating layer 21, for example, high coercivity sendust, An upper magnetic pole layer made of a soft magnetic material such as Malloy or CoZrTa, 23 is a protective layer having a thickness of, for example, 41 + 5 / −2 μm made of an insulating material such as alumina laminated on the write gap layer 19, the coil insulating layer 21 and the upper magnetic pole layer 22. Respectively.

  In the present embodiment, the MR layer 15 has an anisotropic magnetic structure having a multilayer structure of NiFeCr (12.6 nm thickness) / Ta (6.0 nm thickness) / NiFe (25.0 nm thickness) / Ta (3.5 nm thickness). It is formed of a resistance effect (AMR) layer. Although not shown, a lead conductor layer and a magnetic domain controlling hard magnet layer are formed at both ends of the MR layer 15 in the track width direction. The lead conductor layer is formed by laminating a conductive material such as Cu, for example, to a thickness of 200 nm, for example, and the hard magnet layer is, for example, Ta (3.0 nm thickness) / CrTi (5.0 nm thickness) / CoCrPt. A multilayer structure of (60.0 nm thickness) / CrTi (10.0 nm thickness) / Ta (100.0 nm thickness) is formed.

  Of course, the MR layer 15 may be a giant magnetoresistive (GMR) layer or tunnel magnetoresistive (TMR) layer instead of the AMR layer.

  Next, a partial manufacturing process of the inductive write head element in the present embodiment will be described with reference to FIG.

  A lower magnetic pole layer 18 is formed by patterning on the intermediate nonmagnetic layer 17 as shown in FIG. 6A, and a write gap layer 19 is laminated thereon as shown in FIG.

  Next, the first stage coil conductor 20 and the coil insulating layer 21 are formed by patterning as shown in FIG. 5C, and the second stage coil conductor 20 and the coil conductor 20 are formed thereon as shown in FIG. The coil insulating layer 21 is formed by patterning.

  Next, after a through-hole 19a for the back gap portion is formed in the write gap layer 19 as shown in FIG. 5E, the upper magnetic pole layer 22 is formed thereon by patterning as shown in FIG.

Next, at this stage, annealing in a magnetic field is performed to obtain an upper magnetic pole layer 22 'and a lower magnetic pole layer 18' with controlled magnetic anisotropy as shown in FIG. Conditions for annealing in a magnetic field are as follows:
Annealing environment: In vacuum
Annealing temperature: Temperature below the Curie point in the soft magnetic material such as Sendust or Permalloy constituting the lower magnetic pole layer 18 and the upper magnetic pole layer 22, specifically 150 ° C. to 250 ° C.
Annealing time: 60 minutes
Applied magnetic field type: DC magnetic field,
Magnitude of applied magnetic field: 15,920 A / m (200 Oe) to 238,700 A / m (3,000 Oe),
Direction of applied magnetic field: a direction parallel to the laminated surface and parallel to TBS.

  By performing such annealing in a magnetic field, the magnetic domain structure of the pole layer changes. That is, before the annealing, as shown in FIG. 3A, for example, the upper magnetic pole layer 22 has a considerably large number of magnetic domains 22a. However, after the annealing, as shown in FIG. The number of ′ magnetic domains 22a ′ was considerably reduced, and as a result, the magnetic anisotropy in the direction parallel to TBS was increased, and at the same time, the permeability in the direction perpendicular to TBS was increased.

  Thereafter, although not shown in FIG. 2, the wafer process is completed by overcoating the protective layer 23 thereon.

  4 and 5 are histograms of the coil inductance (nH) of the inductive write head element in the wafer when the annealing in the magnetic field is not performed and when the annealing in the magnetic field is performed as in the present embodiment. In these figures, (A) and (B) are histograms for different wafers, and show the results of measuring coil inductance for 9500 elements / wafer, respectively.

  In FIG. 4A where the annealing in the magnetic field is not performed, the average value of the coil inductance is 212.2 (nH) and the standard deviation is 12.53 (nH), and similarly, the annealing in the magnetic field is not performed. In (B), the average value of coil inductance was 218.9 (nH), and the standard deviation was 10.93 (nH).

  In contrast, in FIG. 5A in which annealing was performed in a magnetic field at a temperature of 250 ° C. and an applied magnetic field of 238,700 A / m (3,000 Oe), the average value of the coil inductance was 217.7 (nH), the standard The deviation is 3.59 (nH), and in FIG. 5B, which was also annealed in a magnetic field, the average value of coil inductance was 212.6 (nH) and the standard deviation was 2.56 (nH). It was.

  That is, it can be seen that the standard deviation of the coil inductance in the wafer is greatly reduced from 10 to 13 nH to 2 to 4 nH by performing the annealing in the magnetic field of the present embodiment. Reducing the standard deviation of the coil inductance in this way is very advantageous, especially in a multi-channel thin film magnetic head, because the variation between inductive write head elements in the head is reduced.

  FIGS. 6 and 7 are diagrams showing the frequency characteristics of the coil inductance of the inductive write head element when the annealing in the magnetic field is not performed and when the annealing in the magnetic field is performed as in the present embodiment.

  As shown in FIG. 6, when the annealing in the magnetic field is not performed, an element (sample tk3) in which the coil inductance decreases in the high frequency band is generated. However, as shown in FIG. 7, the annealing in the magnetic field of the present embodiment is performed. When this is performed, there is almost no element that causes a decrease in coil inductance (a decrease of 5 nH or more) in the high frequency band. When actually measuring a large number of thin film magnetic heads, the incidence rate of the inductive write head element in which the coil inductance is reduced by 5 nH or more in a high frequency band of 20 MHz or higher is 7 to 10 by performing annealing in the magnetic field of this embodiment. % Was greatly improved from 0 to 1%.

  As described above, according to the present embodiment, after the upper magnetic pole layer 22 is formed and before the protective layer 23 is formed, annealing is performed in a magnetic field with a DC magnetic field applied in a direction parallel to the TBS. As a result, the number of magnetic domains decreases, the magnetic anisotropy in the direction parallel to the TBS increases, and the magnetic permeability in the direction perpendicular to the TBS increases. As a result, a decrease in coil inductance in the high frequency region can be reliably prevented, and deterioration of write characteristics can be prevented. In addition, since the design change of the inductive write head element is unnecessary, the implementation is easy and the versatility is high. Furthermore, since the annealing is performed in the magnetic field before the formation of the protective layer 23, there is no possibility that unnecessary stress is applied to the magnetic pole and the yoke due to the thermal expansion of the protective layer 23.

  All the embodiments described above are illustrative of the present invention and are not intended to be limiting, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

1 is a cross-sectional view schematically showing a thin film magnetic head manufactured in an embodiment of the present invention. FIG. 7 is a process plan view schematically showing a part of the wafer manufacturing process of the thin film magnetic head in the embodiment of FIG. 1. It is a figure explaining the magnetic domain structure of the top pole layer before and after annealing in a magnetic field. It is a histogram of the coil inductance of an inductive write head element when annealing in a magnetic field is not performed. It is a histogram of the coil inductance of an inductive write head element when annealing in a magnetic field is performed. It is a figure showing the frequency characteristic with respect to the coil inductance of the inductive write head element when not performing annealing in a magnetic field. It is a figure showing the frequency characteristic with respect to the coil inductance of an inductive write head element at the time of performing annealing in a magnetic field.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 11 Underlayer 12 Lower shield layer 13 Lower shield gap layer 14 Upper shield gap layer 15 MR layer 16 Upper shield layer 17 Intermediate nonmagnetic layer 18 Lower magnetic pole layer 19 Write gap layer 20 Coil conductor 21 Coil insulating layer 22 Upper magnetic pole layer 23 Protective layer

Claims (7)

  Forming a lower magnetic pole layer of the inductive write head element, forming a write gap layer on the formed lower magnetic pole layer, forming a coil conductor and an insulating layer insulating the coil conductor on the formed write gap layer; An upper magnetic pole layer is formed on the formed insulating layer and the write gap layer, and after forming the upper magnetic pole layer, annealing is performed in a magnetic field in a state where a magnetic field in a direction parallel to the laminated surface and the magnetic medium facing surface is applied, A method of manufacturing a thin film magnetic head, comprising forming a protective layer after annealing in the magnetic field.   The manufacturing method according to claim 1, wherein the annealing in the magnetic field is a heating to a temperature equal to or lower than a Curie point of the soft magnetic material constituting the lower magnetic pole layer and the upper magnetic pole layer.   The manufacturing method according to claim 2, wherein the soft magnetic material is sendust, permalloy, or CoZrTa.   4. The magnetic field annealing according to claim 1, wherein the annealing in the magnetic field is performed by applying a magnetic field of 15,920 to 238,700 A / m in a vacuum and heating to 150 to 250 ° C. 5. The manufacturing method as described.   The manufacturing method according to claim 1, wherein the applied magnetic field is a direct current magnetic field.   The magnetoresistive effect read head element is formed on a substrate, and the inductive write head element is formed on the formed magnetoresistive read head element. Production method. The manufacturing method according to claim 1, wherein the thin film magnetic head is a multi-channel thin film magnetic head including a plurality of magnetoresistive read head elements and an inductive write head element.

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