JPH10261207A - Thin film magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film magnetic head such as the tracking deviation is not generated by uniformly reproducing the tracking signals coming from the left/right adjacent tracks. SOLUTION: This head is at least provided with two cores 7, 13 holding a gap 11 there between and a coil part, for performing the azimuth recording/ reproducing operation, and it is constituted so that the cores 7, 13 are fabricated to the shapes by an ion beam etching. In this case, the cores 7, 13 are arranged so as to relatively make the positional shift in the longitudinal direction of the gap 11 looking the head from the sliding surface side of a medium. By this arrangement, the tracking signals from the left/right adjacent tracks are uniformly reproduced at the position where the tracking deviation is not being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film magnetic head, and more particularly to a thin-film magnetic head for performing recording and reproduction on an azimuth-recorded recording medium such as a VTR.

[0002]

2. Description of the Related Art In general, thin-film magnetic heads are widely used as magnetic heads for hard disk drives because of their low inductance and excellent frequency characteristics. In recent years, digitalization of VTRs has been progressing, and the use of thin-film magnetic heads is being studied as in hard disks. In a VTR, a signal for tracking is generally superimposed on a recording pattern in order to allow a magnetic head to follow a recording pattern on a magnetic tape at the time of reproduction so that tracking can be performed.

FIG. 4 shows a recording (magnetization) pattern on which a tracking signal is superimposed. As is well known, V
The recording / reproducing mechanism of the TR is provided with a plurality of, for example, two magnetic heads on a rotating drum with different azimuth angles to enable two-channel recording.
The recording and reproduction are performed by driving the recording medium in an oblique direction. Therefore, even-numbered tracks Tr2, Tr4
And the magnetization patterns 1a and 1b of the odd-numbered tracks Tr1, Tr3, Tr5,... Do not form a straight line but have a predetermined angle between the gap of the magnetic head and the direction perpendicular to the running direction of the head. It is recorded in the state that it was. This angle θ is called an azimuth angle.

In this case, the width Tw of the magnetization pattern is slightly smaller than the width of the track of the head because of the recording method in which recording is performed so that adjacent tracks Tr slightly overlap each other. Then, a tracking low-frequency signal is superimposed on one of the even-numbered track and the odd-numbered track, and the frequency is switched for each rotation of the drum. In the figure, a low-frequency signal for tracking is superimposed and recorded on one of the odd-numbered tracks, that is, one channel of the two-channel magnetic head, that is, the odd-numbered track. It is switched and recorded.

A reproduction signal of a channel (even track) other than the channel (odd track) on which the tracking signal is recorded during reproduction, that is, an adjacent track at the time of reproduction of the even track shown in the figure, for example, at the time of reading the track Tr2 A low-frequency crosstalk signal is picked up from Tr1 and Tr3, and the signal intensities are compared.
The tracking control is performed by obtaining the difference between the signal and the b signal and controlling the position of the magnetic head so that the balance is maintained.

Conventionally, as a magnetic material for a thin-film magnetic head, permalloy (NiFe) has been generally manufactured by a plating method. With the increase in coercive force, sendust, cobalt-based amorphous, iron nitride, and the like are being used as magnetic materials used for heads. Here, since a plating method cannot be used to form these materials into a core shape, first, a magnetic film is formed by sputtering or the like, and then a resist having a predetermined core shape is formed on the magnetic film by photolithography. It is common to form and pattern using ion beam etching.

In general, an organic material such as a photoresist is used as an insulating material for a thin-film magnetic head. However, by forming a material in place of permalloy as described above, good magnetic properties can be obtained. In order to obtain it, it is necessary to heat the substrate at the time of forming the magnetic film,
Since it is required to perform a heat treatment at a temperature of ° C., an organic material has a low heat-resistant temperature, and therefore, it is required to use an inorganic material such as SiO ₂ having a high heat resistance as an insulating material. FIG. 5 shows a method of manufacturing a thin film magnetic head in which an inorganic insulating material and a magnetic material are patterned into a core shape by ion beam etching.

First, a 5 μm thick magnetic film 4 of FeTaN or the like is formed on a nonmagnetic substrate, for example, a TlCaO ₃ substrate 3 by a sputtering method, and a resist 5 is patterned into a lower core shape. 2 × 10 ^-4 To
rr, beam acceleration voltage is 600 V, beam incident angle is 1
Ion etching is performed under the condition of 0 degree, and the lower core 5
Is formed (FIG. 5A). FIG. 5B shows a plan view at this time. According to this condition, the etching is completed in about 150 minutes.

[0009] Next, after the resist is removed, a SiO ₂ 6, for example, as an insulating material on the lower core 19 is deposited by a thickness 7μm by sputtering, and planarized polished to lower core 19 is exposed (FIG. 5 (c)) . Next, the formation of a magnetic film, ion beam etching, resist removal, embedding with an insulating material, and planarization polishing are performed in exactly the same manner as in the above steps. Thereby, the gap lower core 7, the lower yoke 8,
An insulating film 9 of SiO ₂ is formed. FIG. 5D shows a sectional view at this time, and FIG. 5E shows a plan view thereof.

Thereafter, a groove is formed in the insulating film 9 in a coil shape by R.
The first coil portion 10 is formed by filling the groove with a conductor, for example, copper, by the IE method or the like.
(F)). A plan view at this time is shown in FIG.
Next, the gap 11 is formed to a thickness of 0.2 μm, for example, by sputtering SiO ₂ or CVD, and then the yoke portion 12 is removed by etching. 14, an upper yoke 15, and an upper core 16 are formed to form a magnetic circuit of the thin-film magnetic head (FIG. 5 (h)).

Although not shown, the first layer coil portion 1
The 0th and second layer coil portions 14 are electrically connected to form a coil portion 17. In this way, a thin-film magnetic head having excellent frequency characteristics and capable of coping with high recording density is manufactured. In FIG. 5H, a broken line 18 indicates a dividing line.

[0012]

However, when the above-described thin-film magnetic head is used for recording and reproduction for a VTR, the problem is that the tracking of the head is shifted to one side during reproduction. occured. For example, in FIG. 4, there is a problem that the magnetic head is shifted to the left side of the track Tr1 when reproducing the track Tr2.

The cause will be described with reference to FIG. FIG. 6 shows a view of the thin-film magnetic head viewed from the medium sliding surface side and a magnetization pattern recorded on a magnetic tape superimposed. Here, since the core shape pattern is formed by ion beam etching in the thin-film magnetic head as described above, the etching side surface, that is, the left and right side walls in the drawing becomes a taper surface of 70 to 80 degrees. . Therefore, for example, the right side wall R of the gap lower core 7 has an angle close to the azimuth angle θ of the track Tr3, whereas the left side wall L on the track Tr1 side has a greatly different angle from the magnetization pattern 1b. . The angle difference between the side walls becomes the output difference of the tracking signal. For example, since the output of the tracking signal on the track Tr3 side is large, the head is shifted to the track Tr1 side.
It shifts to the left as shown in FIG. That is, an effective gap is formed between the side wall R and the right end portion G of the core 13 above the gap, and this contributes to signal reproduction. In FIG. 7, the amount of deviation is exaggerated for clarifying the state of deviation of the head.

This is because the core shape is symmetrical with respect to the center of the gap but not symmetrical with respect to the origin. Ion beam etching is an indispensable technology for applying various high-performance magnetic thin films to thin-film magnetic heads. As long as the core shape is formed by ion beam etching, the core must be symmetrical with respect to the center of the gap. It is difficult. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a thin-film magnetic head that evenly reproduces tracking signals from adjacent tracks on the left and right sides and does not cause tracking deviation.

[0015]

According to a first aspect of the present invention, there is provided a thin film which has at least two cores and a coil portion with a gap therebetween in order to perform azimuth recording / reproducing, wherein the core is formed by ion beam etching. In the magnetic head, the core is arranged so as to be relatively displaced in the length direction of the gap when the thin-film magnetic head is viewed from the medium sliding surface side. This allows
Since the cores sandwiching the gap are relatively displaced from each other, there is no effective gap portion other than the normal gap. For this reason, it is possible to prevent a tracking signal from being picked up in an unintended portion of the thin-film magnetic head, thereby preventing a tracking shift from occurring.

When the core is displaced, one end of each opposing side of the core with the gap interposed therebetween may be set at substantially the same position with the gap interposed. The side set at substantially the same position on both sides of the core is the side where the angle between the direction of the magnetization pattern of the adjacent track and the direction in which the side of the core extends is small. According to a second aspect of the present invention, there is provided a thin-film magnetic head having at least two cores and a coil portion with a gap therebetween for performing azimuth recording and reproducing, wherein the cores are formed by ion beam etching. When viewed from the medium sliding surface side, the opposing sides of the core sandwiching the gap are set to have substantially the same length, and are arranged at substantially the same position via the magnetic gap. Things. As a result, the lengths of the opposing sides of the core sandwiching the gap are set to be substantially the same and are made at substantially the same position, so that it is possible to prevent the tracking signal from being picked up at an unintended portion of the head. . Therefore, it is possible to eliminate occurrence of tracking deviation.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the thin-film magnetic head according to the present invention will be described below in detail with reference to the accompanying drawings. Figure 1 shows the first
FIG. 3 is a view of the thin film magnetic head of the invention of the invention viewed from the medium sliding surface side, in which tracks and magnetization patterns are described together.
The same parts as those of the head shown in FIG. 6 and FIG. The method of manufacturing this thin-film magnetic head is exactly the same as the method described with reference to FIG. 5 except that the arrangement position of some cores is slightly shifted. , Ion beam etching, planarization polishing and the like are repeatedly performed.

As shown in FIG. 1, the end faces of the lower core 19, the lower gap core 7, the upper gap core 13 and the upper core 16 are formed in exactly the same manner, and are formed in a substantially trapezoidal shape having the same dimensions. I have. The side of each core is tapered because the shape of each core is patterned by ion beam etching as described above. Here, FIG. 1 is different from the structure shown in FIG. 6 in that the gap upper core 13 immediately above the gap 11 is moved to the left in the figure.
That is, along the length direction of the gap 11, the track Tr
One end 13b and 7b of the opposing sides 13a and 7a of the upper gap core 13 and the lower gap core 7 are set at substantially the same position with the gap 11 interposed therebetween. Is a point.

In this case, the track width L1 is, for example, 12
μm, the upper base L2 of each core is, for example, 14 μm, the lower base L3 is, for example, 16 μm, and the core width L4 is, for example, 5 μm. Therefore, the shift amount of the core 13 above the gap in the left direction is, for example, 1 μm. It is needless to say that the present invention is not limited to this numerical example. Such a fine shift amount can be easily and accurately controlled by the photolithography technique. The side where one end portions 13b and 7b of the opposing sides of the core coincide with each other is the angle between the direction of the side of the core 7, for example, 7c and 7d, and the direction of the magnetization pattern 1b of the corresponding tracks Tr3 and Tr1. The ends of the smaller sides of α1 and α2 are made to substantially coincide.

With this configuration, the gap length contributing to reproduction of the right track Tr3 in FIG. 1 is L10, and the gap length contributing to reproduction of the opposite left track Tr1 is L11. Are substantially the same, and in this state, both tracks Tr1, T
Since the magnitude of the tracking signal reproduced from r3 is the same, no tracking deviation occurs. In this case, a gap 11 is generated between the left side L (7d) of the lower core 7 and the left portion M of the opposing side 13a of the upper core. This portion is different from the direction of the magnetization pattern 1b. The angles vary widely, and this part rarely acts as an effective gap to pick up the signal.

That is, in FIG.
Side R is closer to the azimuth angle of the corresponding adjacent tracks Tr3 and Tr1 than the side L on the opposite side. However, a magnetic gap is necessary to extract the magnetization as a reproduction signal, and an extra It is considered that the portion acting as a large gap is the portion 21 interposed between the line segments R and G in FIG. Therefore, as shown in FIG.
By slightly shifting the relative position of No. 3, the tracking reproduction signal intensity can be changed. Thus, a position where the magnitudes of the tracking signals from the right and left adjacent tracks become substantially the same can be set as a head position where no tracking deviation occurs.

In the above embodiment, the core 13 above the gap
Is slightly shifted to the left to improve the characteristics. Alternatively, the characteristics may be improved by slightly shifting the core 7 below the gap to the right. Further, in the above embodiment, the characteristics were improved by making the end face dimensions such as the length and width of the lower core 7 and the upper core 13 exactly the same and slightly displacing only one of the cores. However, the present invention is not limited to this. By slightly shortening the lateral dimension L13 of the core that is displaced as in the second invention shown in FIG. Of the end portions 13b and 7b may be substantially the same position with the gap 11 interposed therebetween.

In the illustrated example, the length of the opposing side 13a of the core 13 above the gap is set to be smaller by 2 μm so as to be the same as the length of the opposing side 7a of the core 7 below the gap. Is set to In this case as well, the same operation and effect as in the case of the first aspect described above can be exerted, and the position where the magnitudes of the tracking signals from the adjacent tracks on the left and right are substantially the same is the position where the tracking deviation does not occur. Location.

In the embodiment shown in FIG. 2, since the length L13 of the core 13 is reduced, the core is magnetically saturated depending on the combination of the magnetic material and the recording medium, and the recording performance is reduced. However, in the embodiment shown in FIG. 1, the possibility is lower than in the case shown in FIG. Further, in the embodiment shown in FIG. 1, shifting the core in the direction of the track Tr1 has the effect of reducing the signal from the track Tr3 and increasing the signal from the track Tr1.

FIG. 3 is a graph showing the reproduction characteristics with respect to the tracking position of the thin film magnetic head of the present invention and the conventional thin film magnetic head.
In the figure, the center part shows a normal tracking position.
As is clear from the graph, in the conventional thin-film magnetic head, the output is maximum at a position where the tracking position is greatly deviated from the proper position, whereas in the thin-film magnetic head of the present invention, the tracking position is at the proper position. Indicates that the output is at a maximum, indicating good characteristics. It should be noted that each value in the above description is merely an example, and it goes without saying that the azimuth angle, the track width, and the like differ depending on the format of the system used.

[0026]

As described above, according to the thin-film magnetic head of the present invention, the following excellent functions and effects can be exhibited. According to the first aspect of the present invention, one of the cores sandwiching the gap is relatively slightly displaced in the gap length direction, so that an effective gap is generated at an unintended portion. Can be prevented.
Therefore, the tracking signals from the adjacent tracks on the left and right can be reproduced evenly at the head position where no tracking deviation occurs. Therefore, occurrence of tracking deviation can be suppressed. According to the second invention,
Of the cores sandwiching the gap, the length of one of the cores is set slightly smaller so that both ends of the opposing sides are substantially at the same position, so that it is possible to prevent an effective gap from being generated in an unintended part. . Therefore, the tracking signals from the adjacent tracks on the left and right can be reproduced evenly at the head position where no tracking deviation occurs. Therefore, occurrence of tracking deviation can be suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view showing a medium sliding surface side of a thin film magnetic head according to a first invention.

FIG. 2 is a plan view showing a medium sliding surface side of a thin film magnetic head according to a second invention.

FIG. 3 is a graph showing reproduction characteristics with respect to a tracking position of the thin film magnetic head of the present invention and a conventional thin film magnetic head.

FIG. 4 is a diagram showing a magnetization pattern on which a tracking signal is superimposed in the azimuth recording method.

FIG. 5 is a process chart showing a manufacturing process of the thin-film magnetic head.

FIG. 6 is a plan view showing a medium sliding surface side of a conventional thin film magnetic head.

FIG. 7 is a diagram illustrating a state when a tracking shift occurs.

[Explanation of symbols]

1a, 1b: magnetization pattern, 2: magnetic tape (recording medium), 7: core below the gap, 7a: opposite side, 7b: end, 11: gap, 13: core above the gap, 13a ...
Opposite side, 13b: end, 16: upper core, 19: lower core, Tr: track.

Claims (4)

[Claims] 1. To perform azimuth recording / reproduction, at least two cores and a coil portion with a gap therebetween are provided,
In the thin-film magnetic head in which the core is shaped by ion beam etching, the core is relatively displaced in the length direction of the gap when the thin-film magnetic head is viewed from the medium sliding surface side. A thin film magnetic head characterized by the above-mentioned. 2. The thin-film magnetic head according to claim 1, wherein one end of each of the opposite sides of the two cores sandwiching the gap is set at substantially the same position across the gap. 3. The side in which one end of each of the opposite sides is set at substantially the same position is the direction of the magnetization pattern of the adjacent track and the direction in which the side of the core extends in the arrangement viewed from the medium sliding surface. 3. The thin-film magnetic head according to claim 2, wherein the angle of the thin-film magnetic head is smaller. 4. In order to perform azimuth recording / reproduction, at least two cores and a coil portion with a gap therebetween are provided,
In the thin-film magnetic head in which the core is shaped by ion beam etching, when the thin-film magnetic head is viewed from the medium sliding surface side, the opposing sides of the core sandwiching the gap have substantially the same length. Characterized in that they are arranged at substantially the same position via the magnetic gap.