JPH05159247A - Magneto-resistance effect head - Google Patents

Abstract

PURPOSE:To provide the shielding type MR head which has a high resolving power and is suitable for a high recording density. CONSTITUTION:The shielding type MR head has a structure laminated with a lower shield 5, an inter-lower shield gap 7, a bias film 3, a shunt film 2, an MR element layer consisting of an MR film 1, an electrode 4, an inter-upper shield gap 8 and an upper shield 6. The distance 9 between the MR film and the upper shield of such head and the distance 10 between the MR film and the lower shield are equaled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield type magnetoresistive head for use in magnetic recording devices such as magnetic disk devices and magnetic tape devices.

[0002]

2. Description of the Related Art A magnetoresistive head (hereinafter referred to as an MR head) has a high reproducing sensitivity and a reproducing output does not depend on a relative speed between a magnetic recording medium and a magnetic head. This device is advantageous for higher density and smaller size. In an MR head, a magnetoresistive effect element (hereinafter referred to as an MR element) is generally arranged perpendicularly to a magnetic recording medium and detects a component of a magnetic flux generated from the magnetic recording medium which is perpendicular to the magnetic recording medium. To do. As an example of an MR head with improved resolution, a shield type MR head in which a magnetic shield made of a soft magnetic material is arranged on both sides of an MR element is known, and it is published in 1975.・ Magnetics Magazine MAG-11 Vol. 1206, JP-A-60-151
No. 816, JP-A-63-184906 and JP-B-63-50769.

In the shield type MR head, the magnetic shield absorbs an excessive magnetic flux of the magnetic flux generated from the magnetic recording medium, and the magnetic flux detected by the MR element from the low linear recording density region to the high linear recording density region. The amount is almost constant. Therefore, the output voltage reproduced by the MR element has a constant amplitude from the low linear recording density region to the high linear recording density region, and it is possible to obtain a signal with small waveform interference and no read error.

[0004]

In order to increase the resolution of the MR head by arranging the magnetic shield, it is effective to make the gap layer thin in order to reduce the distance between the MR film and the shield. However, thinning the gap layer involves a risk of electrically shorting the MR element layer or the electrode and the shield. Therefore, the thickness of the gap layer is limited by the quality of the gap layer material and the shape of the electrode, and needs to be determined according to the linear recording density.

FIG. 3 is an example of a sectional view of a conventional shield type MR head. The lower shield gap 7 and the upper shield gap 8 are made of SiO ₂ , and each has a thickness of 0.
2, 0.3 μm. The gap between the upper shields is larger than the gap between the lower shields to avoid shorts at the corners of the electrodes. In addition, the MR film 1, the shunt film 2,
The bias film 3 has film thicknesses of 0.04, 0.02,
It is 0.06 μm. It is the distance between the MR element layer and the upper and lower shields that determines the resolution. The distance 10 between the MR element layer and the lower shield 5 is 0.2 μm, whereas The distance 9 from the upper shield 6 is different from 0.38 μm. The effect of different gap lengths above and below on resolution was not clarified. In the figure, 4 indicates an electrode.

An object of the present invention is to provide a magnetoresistive head capable of obtaining high resolution.

[0007]

The present invention is directed to a magnetoresistive effect element comprising a lower shield layer, a lower shield gap layer, a magnetoresistive effect layer and a bias layer, an electrode layer, and an upper shield gap layer on a non-magnetic substrate. In a magnetoresistive effect head having a structure in which an upper shield layer is laminated, the distance between the magnetoresistive effect layer and the lower shield layer is equal to the distance between the magnetoresistive effect layer and the upper shield layer. And

[0008]

[Operation] As an analysis of the resolution of the shield type MR head,
A method using the reciprocity theorem by Davis et al. Is shown in 1975, iE, E, Transactions on Magnetics, MAG-11, pp. 1689. There, the half-value width (hereinafter, referred to as the following, of the isolated reproduction waveform when the distance between the MR film and the upper and lower shields is equal.
PW ₅₀ ). When the model used there is applied when the distance between the MR film and the upper and lower shields is different, the PW ₅₀ is

[0009]

[Equation 1]

[0010] Where d, a, T, g1, g2
Are spacing, magnetization transition length, MR film thickness, MR
The distance between the film and the upper shield, and the distance between the MR film and the lower shield. The first term is caused by the difference in the distance between the MR film and the upper and lower shields, and the difference in the distance is PW.
It can be seen that increasing ₅₀ increases the resolution. Further, the effect becomes stronger as the spacing and the magnetization transition length become smaller. Therefore, by making the distance between the MR film and the upper shield equal to the distance between the MR film and the lower shield, a high resolution can be obtained. A shield type MR head can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings are sectional views showing an embodiment of the present invention.

This magnetoresistive head is manufactured as follows. First, a lower shield 5 using permalloy having a thickness of 3 μm on a ceramic non-magnetic substrate is formed by a plating method and patterned to have a width of 100 μm by ion milling. On top of that, 0.23 μm thick Si
The lower shield gap 7 using O ₂ is formed by the sputtering method. Furthermore, Co with a thickness of 0.05 μm
Bias film 3 using ZrMo, T having a thickness of 0.02 μm
The shunt film 2 using i and the MR film 1 using permalloy having a thickness of 0.04 μm are formed by the sputtering method. The bias film 3 is magnetically coupled to the MR film to apply a bias magnetic field, and the magnetoresistive effect of the MR film is detected. The shunt film 2 magnetically separates the MR film 1 and the bias film 3. An electrode 4 made of Au and having a thickness of 0.2 μm is formed thereon by an evaporation method, and the MR element and the electrode 4 are formed by using a photolithography technique and an ion etching technique.
Are patterned at the same time. Next, the electrode 4 is removed by chemical etching only in the detection portion 8 μm of the MR element. Further, a gap 8 between upper shields using a SiO ₂ film having a thickness of 0.3 μm is formed by a sputtering method, and an upper shield 6 using permalloy having a thickness of 3 μm is formed thereon by a plating method. A pattern having a width of 100 μm is formed by using the photolithography technique and the ion etching technique.

In this embodiment, the distances 9 and 10 between the MR film 1 and the upper and lower shields 6 and 5 are both 0.3 μm. Similarly, the lower shield gap 7 is 0.2μ.
m and the gap 8 between the upper shields was 0.3 μm. In Comparative Example 1, the distances between the MR film and the upper and lower shields are 0.33 μm and 0.27 μm, respectively.
m. Further, Comparative Example 2 was obtained by exchanging the positions of the MR film 1 and the bias film 3 in Example 1. In Comparative Example 2, the distances between the MR film and the upper and lower shields are 0.23 μm and 0.37 μm, respectively. .

When the recording density characteristics of these shield type MR heads were measured, the results shown in Table 1 were obtained. Output of 5 kFCl and 50 kFC as a measure of linear recording density
A resolution defined by the ratio of l outputs was used. Although the sum of the distances between the MR film and the upper and lower shields of these heads is all 0.6 μm, the head of Example 1 having the same distance between the MR film and the upper and lower shields has the best resolution. It can be seen that a high linear recording density can be achieved.

[0015]

[Table 1]

Next, an example using the shunt bias method will be shown as a second embodiment. FIG. 2 is a sectional view showing the second embodiment. In this embodiment, the MR element is composed of only the MR film 1 made of permalloy and the shunt film 2 made of Ti.
The magnetic field generated by the current flowing through the i film becomes the bias magnetic field. Other configurations are the same as those of the first embodiment shown in FIG. The MR film 1 has a thickness of 0.04 μm, the shunt film 2 has a thickness of 0.15 μm, and the lower shield gap 7 is 0.2 μm.
m, the gap 8 between the upper shields is 0.35 μm, and M
The distance between the R film and the upper and lower shields is 0.35 μm.
Is. In the same manner, a head in which the stacking order of the MR film 1 and the shunt film 2 was changed was prepared, and was set as Comparative Example 2. Comparative Example 3
The distance between the MR film of the head and the lower shield is 0.2μ
m, and the distance between the MR film and the upper shield is 0.5 μm.
m.

When the recording density characteristics of these shielded MR heads were measured and the resolution was determined, the head of Example 2 had a resolution of 50% and the head of Comparative Example 3 had a resolution of 32%. From this example, it is understood that the present invention is also applied to the shield type MR head by the shunt bias method.

Needless to say, the results obtained by the present invention hold true for bias methods other than the soft film bias method and the shunt bias method shown in the examples.

Although permalloy is used as the shield in the above embodiment, the same effect can be obtained with other soft magnetic materials.

[0020]

As described above, in the magnetoresistive head according to the present invention, high resolution can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a magnetoresistive effect head according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a magnetoresistive effect head according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional shield type MR head.

[Explanation of symbols]

 1 MR film 2 Shunt film 3 Bias film 4 Electrode 5 Lower shield 6 Upper shield 7 Lower shield gap 8 Upper shield gap 9 Distance between MR film and lower shield 10 Distance between MR film and upper shield

Claims (1)

[Claims] 1. A magnetoresistive effect element including a lower shield layer, a lower shield gap layer, a magnetoresistive layer and a bias layer, an electrode layer, and an upper shield gap layer on a nonmagnetic substrate.
In a magnetoresistive effect head having a structure in which an upper shield layer is laminated, the distance between the magnetoresistive effect layer and the lower shield layer is equal to the distance between the magnetoresistive effect layer and the upper shield layer. Magnetoresistive head.