JPH03116509A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain the thin-film magnetic head having a narrow track and with the Barkhausen noise reduced by forming the track with a narrow protrusion partly projecting in the thickness direction of a thin-film magnetic core and making the thickness of the protrusion continuous from the narrow magnetic domain of the core. CONSTITUTION:A magnetic gap is formed at the part opposed to a magnetic recording medium by a first magnetic thin-film core 1 and a second magnetic thin-film core 2 through a nonmagnetic thin film 5, and at least one of the cores has a narrow part 21 in the cross direction of the track at the part opposed to the magnetic recording medium. A narrow protrusion 22 projecting in the thickness direction is provided to the narrow part 21 of at least one of the cores, and the track width WT of the gap 8 is controlled by the width of the protrusion 22. The thickness of the protrusion 22 is controlled so that the protrusion is magnetized in follow-up to the magnetization of the magnetic thin-film part. As a result, the effect of the circulating magnetic domain is effectively avoided, and a narrow-track thin-film magnetic head with the Barkhausen noise reduced is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to thin film magnetic heads, particularly thin film magnetic heads having narrow track widths.

[Summary of the invention]

The present invention relates to a thin-film magnetic head, in which a first magnetic thin-film core and a second magnetic thin-film core are laminated with a non-magnetic thin film interposed therebetween at a portion facing a magnetic recording medium to form an operating magnetic gap. , at least one of the magnetic thin film cores has a narrow part that is narrow in the track width direction at the part facing the magnetic recording medium, and further has a narrow part of the at least one magnetic thin film core in the thickness direction. A convex portion that protrudes and has a narrower width than the narrow portion is provided so that the track width of the working magnetic gap is regulated by the width of the convex portion, and the thickness of the convex portion is determined by the thickness of the magnetic thin film having the convex portion. By doing so, the operating magnetic gap having the required narrow trunk width can be configured to effectively avoid the occurrence of Barkhausen noise. do.

[Conventional technology]

As recording density is improved, track narrowing is being promoted, and along with this, research and development into narrowing the tracks of magnetic heads is remarkable.

For example, in Japanese Unexamined Patent Publication No. 55-4723, a convex portion that protrudes into the magnetic gap and forms a reproduction gap that saturates during recording is provided to make the gap length and track width during reproduction smaller than that during recording. A magnetic head having such a structure has been proposed.

Furthermore, Japanese Patent Application Laid-Open No. 60-95712 also discloses a structure in which the magnetic gap portion of the core that regulates the track width is cut from both sides to make it narrower. However, in such a bulk type magnetic head, it is difficult to provide a sufficiently narrow track width.

In contrast, in a thin-film magnetic head, fine patterns can be easily formed, which increases the possibility of narrowing the track. On the other hand, for example, in Japanese Unexamined Patent Publication No. 60-57520, in the thin film magnetic head, the length of the rear part of the soft magnetic thin film in the track width direction is increased and the axis of easy magnetization is directed in the track width direction, thereby achieving high recording performance. Proposals have been made to make it possible to obtain a good S/N ratio in terms of density. However, even in a structure in which the width in the track width direction is increased at the rear part of the thin film magnetic head, that is, the width is narrowed at the part facing the magnetic recording medium, the track width is still narrower than several micrometers. In the case of width, the effect of shape anisotropy occurs, and the desired direction of magnetization, that is, the magnetic domain structure along the track width direction, becomes impossible, and the magnetic domain in the direction perpendicular to the track width becomes dominant. Barkhausen noise is generated, leading to a decrease in S/N.

On the other hand, for example, IEICE Technical Report, IEICE Technical Report V
o1.88. Research and development on narrowing the track is also carried out in Na305, published November 30, 1988, pages 33 to 38, but in this case as well, the width of the magnetic thin film in the track width direction is narrowed. In other words, it is merely a two-dimensional consideration.

To explain an example of a conventional thin film magnetic head, for example, FIG. 1θ shows a plan view thereof, and FIGS. The first magnetic thin film core (1) and the second magnetic thin film core (1) are placed on the base (3).
Between the front portions of each of the first and second magnetic thin film cores (1) and (2), the magnetic thin film cores (2) are laminated and extend toward the surface (4) facing the magnetic recording medium. An operating magnetic gap g is formed by interposing a nonmagnetic thin film (5) serving as a gap spacer. (6) is a winding layer, and the first and second magnetic thin film cores (1) and (2) are magnetically coupled to each other behind the winding layer and have the above-mentioned operating magnetic gap g@magnetic closed magnetic field in the magnetic path. It is made up of roads.

As a method for obtaining this type of thin film magnetic head, for example, a frame plating method is used. This frame plating method will be explained with reference to FIGS. 13 to 15.
In FIGS. 13 to 15, each figure A shows an enlarged plan view in each step, and each figure B shows a sectional view taken along the line BB of each figure A. The substrate (3) is, for example, M, o, -Ti
For example, an alumina Al2O3 layer (3B) is placed on the c substrate (38).
) is formed by adhesion.

First, as shown in FIG. 13, a conductive base film (7) such as a Ti film is deposited on the layer (3B) of the base (3) by sputtering or the like, and a resist frame made of photoresist ( 8) is formed. This resist frame (8) can be formed to a desired width along the outline of the first magnetic thin film core (1) to be finally obtained, for example, by exposing and developing a photoresist layer coating pattern. Using this resist frame (8) as a plating resist, a first magnetic thin film (11) made of permalloy (Ni-Fe) or the like is placed on the base film (7) under the application of a magnetic field to generate an axis of easy magnetization in the track width direction. Formed by electroplating.

As shown in FIG. 14, at least the resist frame (8
) A resist cover (9) is deposited on the portion surrounded by (1) by, for example, photoresist coating, exposure, or phenomenon. Then, using this resist cover (9) as an etching mask, the first magnetic thin film (11) in the portion not covered by this, that is, outside the resist frame (8).
is removed, and the remainder of the first magnetic thin film (11) constitutes a first magnetic thin film core (1) in a portion surrounded by the resist frame (8). Then resist frame (
8) and the resist cover (9) are removed, and then, if necessary, the base film (7) exposed to the outside is removed by etching.

Thereafter, as shown in FIG. 15, At! becomes a gap spacer of the required thickness. Non-magnetic thin film (5) such as z O:+
is deposited over the first magnetic thin film core (1), and further a 5i02 insulating layer (10), for example, is deposited on the part other than the part that will finally form the operating magnetic gap g, and a conductive layer (10) is deposited on this. The layers are sequentially deposited over the entire surface and patterned by photolithography to form a winding layer (6) which becomes, for example, a spiral head winding. This winding layer (6) is then covered with further insulation J! such as 5i02! (13), permalloy or the like is deposited by sputtering or the like, and a predetermined pattern is formed by photolithography to form a second magnetic thin film core (2). This second magnetic thin film core (2) is formed across the winding layer (6), and the non-magnetic gap spacer layer (5) is connected to the insulating layer (10) at the rear of the second magnetic thin film core (2).
) and (13), a part of which is connected to the first magnetic thin film core (1) and magnetically coupled through the window (I4). A window (15) is also formed in the insulating layer (13) on one end of the winding layer (6), through which one terminal conductive layer (16) is applied. Winding layer (
6), for example, from the outer end to the other terminal conductive layer (1
7) is formed by extending. First and second magnetic thin film cores (
1) and (2) are polished from the front to the position indicated by the chain line a, forming a surface (4) facing the magnetic medium as shown in FIG. 14, thereby forming a thin film magnetic head.

In order to achieve a narrow trunk in such a thin film magnetic head, the front width WT is made narrower in accordance with the track width.In this case, in order to realize a narrow track core using the frame plating method described above, A technique for forming a resist frame and a resist cover (9) having a high aspect ratio is required. The limit of the aspect ratio (thickness/width) in the conventional technology is about 2 to 3. Considering the magnetic saturation of the core, if the core thickness is 3 μm, that is, the frame height is 3 μm, the minimum limit of the track width Wa is about 1 μm. becomes.

Furthermore, in film formation by plating, the composition changes in the front narrow portion depending on the track width, and soft magnetic properties cannot be obtained. Therefore, in the case of such a structure, there is a limit to the minimum track width.

In addition, in this type of thin film magnetic head, the conventional technique involves forming a core by an etching method, that is, covering a magnetic thin film formed by plating, vapor deposition, sputtering, etc. with a mask having a core shape and removing unnecessary portions by etching. Ar ion shower etching is applied as a typical high-precision etching method. This is a method in which accelerated Ar ions are irradiated onto the workpiece and the workpiece is removed by elastic collision. irradiate diagonally. As a result, the etching mask or resist recedes (pattern thinning), and the cross-sectional shape of the workpiece after etching becomes trapezoidal. In addition, since the selectivity ratio of Ar ion shower etching, that is, the ratio of the etching rate of the thin film core material to the etching rate of the mask material, for example, photoresist, is approximately 1, the aspect ratio of the core cross-sectional shape is The limit is approximately 0.8. That is, the minimum track width that can be processed by Ar ion shower etching is currently 1.25 times or more the core thickness.

In addition, in this type of thin-film magnetic head, as mentioned above, as the track becomes narrower, S/N noise such as Barkhausen noise increases.
The problem of decreasing N arises. This will be explained with reference to FIG. 16. FIG. 16 shows an almost ideal magnetic domain structure. That is, the magnetic properties of the core of a thin film magnetic head are greatly influenced by the magnetic domains generated within the core, and control of the magnetic domains within the core is an important issue. That is, the ideal magnetic domain structure consists of a so-called 180° domain wall (61) in which the main domain direction is perpendicular to the flow of magnetic flux, and there are few unnecessary circulating magnetic domains (62). That is, this circulating magnetic domain affects noise characteristics such as Barkhausen noise and the effective track width.

Normally, this type of thin film magnetic core material is made to have anisotropy in the track width direction. For example, a method of giving magnetic anisotropy in the track width direction by applying an external magnetic field during plating is known. It will be done. However, as the track width WT at the front part becomes narrower, the demagnetizing field at the narrower part at the front end increases, making it difficult to obtain a 180" domain wall perpendicular to the flow of magnetic flux, and also at both ends in the track width direction. There is a limit to the narrowing of the track because the influence of the circulating magnetic domain that occurs on the ground cannot be ignored.

[Problem to be solved by the invention]

The present invention aims to promote narrowing of the track in the above-mentioned thin film magnetic head by reducing Barkhausen noise that accompanies the narrowing of the track.

(Means for Solving the Problems) In the present invention, FIG. 1 shows a plan view thereof, FIG. 2 shows a further enlarged cross section on line A-A in FIG. 1, and FIG. As shown in the cross-sectional view taken along the line B-B, the first magnetic thin film core (1) and the second magnetic thin film core (2) are connected to each other via a nonmagnetic thin film (5) at the part facing the magnetic recording medium. They are stacked to form an actuating magnetic gap g, with at least one magnetic thin film core, in the illustrated example, both film cores (
1) and (2) form a narrow part (21) narrowed in the track width direction in the part facing the magnetic recording medium, that is, a sub-track part, and furthermore, in the illustrated example, at least one of the magnetic thin film cores A convex portion (22) that protrudes in the thickness direction of the first magnetic thin film core (1) and is narrower than the sub-track portion of the narrow portion (21) is provided,
The track width WT of the working magnetic gap g is regulated by the width of the convex portion (22). In particular, the thickness t of this convex portion (22) is such that the direction of magnetization of the magnetic thin film core (1) on which this convex portion (22) is provided, that is, the magnetization state that follows the magnetic domain structure, that is, the thickness that results in a magnetic domain structure. Furthermore, the thickness is selected to be 1 μm or less, for example, 0.3 μm in consideration of off-track characteristics.

[Effect]

As described above, in the present invention, the track width W7 is regulated by the narrow convex portion (22) partially protruding in the thickness direction of the thin film magnetic core. The thickness of (22) was selected to maintain a continuous condition from the magnetic domain of the narrow part of the thin film core where the convex part (22) is provided, so that the width is made narrower. Nevertheless, it is possible to construct a thin film magnetic head with a narrow track, for example, several micrometers or less, for example, one micrometer or less, which can effectively avoid the influence of circulating magnetic domains and reduce Barkhausen noise.

〔Example〕

An embodiment of the present invention will be further described with reference to FIGS. 1 to 3.

In the present invention, a thin film magnetic head is constructed by laminating a first magnetic thin film core (1) and a second magnetic thin film core (2), and FIGS.
Portions corresponding to those in FIG. 12 are designated by the same reference numerals, and redundant explanation will be omitted.

Even in this case, as explained in FIGS. 10 to 12, it is possible to form a desired pattern by frame plating or by forming a magnetic thin film on the entire surface and later etching it, but in the present invention, At least one magnetic thin film core forming an operating magnetic gap g laminated with a non-magnetic thin film (5) interposed therebetween in the part facing the magnetic recording medium, for example, a narrow width in front of the first magnetic thin film core (1). The portion (21) is further provided with a narrower convex portion (22). Width W in the track width direction at this narrow width portion (21)
The width should be such that shape anisotropy, demagnetizing field, and circumferential magnetic domains are unlikely to occur.

Various methods can be used to form the convex portion (22), and one example will be explained with reference to FIGS. 4 to 9, respectively. 1 and 2 respectively show cross sections at the forming portions of the sub-track portions (narrow width portions (21)).

In the example shown in FIG. 4, the convex portion (22) is provided only on the first magnetic thin film core (1).

In this case, first, as shown in FIG. 4A, a magnetic thin film (41) having a thickness thicker than the first magnetic thin film core (1) to be finally obtained is placed on the underlayer (7) of the substrate (3) by applying, for example, a magnetic field. It is formed entirely by electroplating under the . Then, an etching resist (50) such as a photoresist is formed on a portion of the magnetic thin film (41) where the convex portion (22) will finally be formed by an optical method, that is, photoresist coating, exposure, and phenomenon. As shown in Figure 4B, the resist (
Etching is performed using resist (50) as a mask to remove resist (50).
0) Etch other parts so as to form a convex part (22) that is not etched below. Thereafter, as shown in FIG. 4C, an etching resist (51) made of, for example, photoresist is similarly deposited over the entire pattern of the first magnetic thin film core (1) finally obtained. Next, using this resist (51) as a mask, the portions of the magnetic thin film (41) to which the resist (51) is not adhered are removed by, for example, ion shower etching using Ar.

After that, if the etching resist (51) is removed, the fourth
As shown in the figure, a first magnetic thin film core (1) in a predetermined pattern is formed.

The first magnetic thin film core (1) thus formed has a wide part at the rear, a narrow part (21), that is, a sub-track part, at the front, and a convex part (22) on top of this. ) is formed. This first magnetic thin film core (1) has a thickness T of, for example, 3 μm, a height t of a convex portion of 1 μm or less, for example, 0.3 μm, and a width W of a narrow portion (21) of 7 to 10 μm.
, the width of the convex portion (22), that is, the track width W, is 1 to 2μ.
M can be done.

In the example shown in FIG. 4, etching for patterning the first magnetic thin film core (1) is performed after etching for forming the convex portion (22), but this is the opposite. It is also possible to pattern the first magnetic thin film core (1) first and then perform thinning etching to form the convex portions (22).

In the example shown in FIG. 4, the magnetic thin film (41) is formed on the entire surface, but the first magnetic thin film core (1) with the desired pattern is finally obtained by, for example, a frame plating method. 4. A and B.
It is also possible to perform etching to form the convex portions (22) described in .

Further, the first magnetic thin film core (1) can be made of different magnetic materials in the convex portion (22), for example, materials with different saturation magnetic flux densities. An example of this case will be explained with reference to FIG. In this case, first, as shown in FIG. 5A, for example, a first magnetic thin film core (1) having a required thickness T is formed by a frame plating method or the like. As shown in FIG. 5B, a core material layer (53) having a thickness t of the convex portion (22) finally obtained is formed. As shown in FIG. 5C, an etching resist (50) is formed in the area where the convex portion (22) is formed, and as shown in the fifth diagram, the core material layer (53) is etched using this as a mask. Only the portion under the resist (50) to which the resist (50) is adhered is left as a convex portion (22).

Further, the formation of the convex portion (22) is not limited to the case where the convex portion (22) is formed by etching. For example, as shown in FIG.
) on the base film (7) on).
A convex portion, that is, a pillow (54) having a shape and thickness corresponding to the shape and thickness of 2) is formed, for example, from the same material as the base film (7), and a desired pattern and pattern are formed thereon by, for example, a frame plating method. First magnetic thin film core (1) with thickness T
By forming a protrusion (22) on the pillow (54). When using this pillow (54), it is not limited to forming a magnetic thin film core (1) with a desired pattern by frame plating, but also by forming a magnetic thin film on the entire surface of the pillow (54) and then etching it. It can also be formed into a desired pattern.

In addition, the cross-sectional shapes of the convex portion (22) and the narrow portion (21) are not limited to rectangular shapes as shown in the examples of the figures mentioned above. For example, as shown in FIG. 21) can be made to become gradually thinner at both ends, or from the convex part (22) to the narrow part (21) as shown in FIG. Core (1)
To obtain this, the cross-sectional shape of the pillow (54) is divided into a convex portion (22) and a narrow portion (21) by the method explained in FIG.
) can be formed by selecting the appropriate cross section.

In addition, in the above-mentioned example, the convex portion (
22), but the second magnetic thin film core (
2) or both magnetic thin film cores (1) and (2). In this case as well, the non-magnetic thin film (5) of the operating magnetic gap is interposed on the convex portion (22) of the second magnetic thin film core (1), and an insulating layer is formed as shown in FIGS. 1 to 3. (10), winding layer (6), insulating layer (
13), etc., a non-magnetic material (55) such as SiO□ is arranged as shown in FIG. Magnetic thin film core (2)
It can be formed by forming. In this case as well, by selecting the cross-sectional shape of the pillow (55), the second magnetic thin film core (2)
It is also possible to take various cross-sectional shapes.

〔Effect of the invention〕

As described above, in the present invention, the track width W7 is defined by the narrow convex portion (22) partially protruding in the thickness direction of the thin film magnetic core. ) was selected to maintain a continuous condition from the magnetic domain in the narrow part of the thin film core where the convex part (22) is provided, even though the width is narrow. A narrow track, for example, several micrometers, can effectively avoid the effects of circulating magnetic domains and reduce Barkhausen noise.
For example, a thin film magnetic head with a thickness of 1 μm or less can be constructed.

[Brief explanation of drawings]

FIG. 1 is an enlarged plan view of an example of a thin film magnetic head according to the present invention, and FIGS. 2 and 3 are lines A-A and B-B.
4A-D and 5A-D are respective manufacturing process diagrams, FIGS. 6 to 9 are sectional views of the magnetic thin film core, and FIG. 1O is a conventional thin film magnetic Figures 11 and 12 are enlarged cross-sectional views of an example of the head.
13 to 15 are structural process diagrams thereof, and FIG. 16 is an explanatory diagram of magnetic domains. (1) and (2) are first and second magnetic thin film cores, (2)
1) is the narrow part (auxiliary track part'), and (22) is the convex part. Fig. 2 Fig. 4 Fig. Mangyokusenba H Sarakoa/l-#u+ side view Fig. 8 Fig. 4 Aoi core sectional view Fig. 8 Fig. 16 Access to the traffic Plane whistle of the paper head relationship with

Claims (1)

[Scope of Claims] A first magnetic thin film core and a second magnetic thin film core are laminated with a nonmagnetic thin film interposed therebetween in a portion facing a magnetic recording medium to form an operating magnetic gap, and at least one The magnetic thin film core has a narrow part that is narrow in the track width direction at the part facing the magnetic recording medium, and the narrow part of at least one of the magnetic thin film cores has the above narrow part that protrudes in the thickness direction. A convex portion narrower in the track width direction than the narrow portion is provided so that the track width of the working magnetic gap is regulated by the width of the convex portion, and the convex portion is a magnetic thin film having the convex portion. A thin film magnetic head whose thickness is selected so that the magnetization state follows the magnetization state of the thin film magnetic head.