JPH0567314A - Manufacture of magneto-resistance effect type head - Google Patents

Abstract

PURPOSE:To manufacture a magneto-resistance effect type head without distortion of a reproducing wave by forming an exchange coupled film and heating the exchange coupled film at higher than a Curie point while an external magnetic field in the same direction to an easy magnetization direction of a magneto-resistance effect element is impressed. CONSTITUTION:A specified film thickness of Co system amorphous alloy film superior in the flatness in used for a shield film 10. An extra thin insulated layer 11 consists of an alumina film and a magneto-resistance element 12 consists of a 'Permalloy' and the film thickness is, for example, less than 15nm. On the 'Permalloy', a specified film thickness of an FeMn 13 and a Nb shunt film 14 whose Curie point is around 160 deg.C are formed as the exchange coupled film. The magneto-resistance effect type head which the exchange coupled film 13 is formed on at least one portion of the magneto-resistance effect type head, after the coupling film 13 is formed, is heated at higher than the Curie point, while the external magnetic field in the same direction to the easy magnetization direction of the resistance element 12 is impressed, and the magneto-resistance effect head is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing element of a magnetic head used in a magnetic disk device or a magnetic tape device, and more particularly to a magnetoresistive head having high reproducing sensitivity and no reproduced waveform distortion.

[0002]

2. Description of the Related Art A known example in which FeMn is formed as an antiferromagnetic film on a magnetoresistive effect element to suppress a reproduced waveform distortion caused by Barkhausen noise is described in, for example, I.E.
EE Transactions ON MAGNETICS VOL.25, No.
5, 1989. Here, only the device characteristics are examined at the wafer stage, and no problems have been extracted after examining the recording / reproducing characteristics by forming a head. There are problems in the wafer process and the machining process when the magnetoresistive effect element is actually used as a head or used as a reproducing element of a recording / reproducing separated type head. For example,
In the wafer process of the recording / reproducing separated type head in which the recording head is formed on the reproducing head, there is a high temperature process of hardening the resist insulating layer for embedding the coil of the recording head. In this process, it is necessary to heat the wafer to a high temperature of about 200 ° C. When a FeMn film is used as the exchange coupling film, the Curie point of this film is 1
It is around 60 ° C. For this reason, the magnetization direction of the FeMn film is dispersed corresponding to the magnetization direction of the magnetoresistive effect element which is dispersed under the influence of the stray magnetic field during the high temperature process of curing the resist insulating layer (about 200 ° C.). There's a problem. When the element is heated to a temperature above the Curie point of the exchange coupling film in a state where the magnetization direction of the magnetoresistive effect element is dispersed, the magnetization direction of the exchange coupling film varies and disturbs the magnetic domain structure of the magnetoresistive effect element. There arises a problem that a reproduced waveform distortion occurs due to Barkhausen noise during a reproducing operation.

[0003]

SUMMARY OF THE INVENTION According to the present invention, the magnetization directions of the magnetoresistive effect element and the exchange coupling film, which are varied during the wafer process or the machining process, are easily magnetized when the magnetoresistive effect element is formed. The aim is to align perfectly in the direction.

[0004]

The above object is to achieve a Curie point of the exchange coupling film in an atmosphere in which an external magnetic field is applied to the head element in the same direction as the easy magnetization direction of the magnetoresistive effect element after the wafer process or the machining process is completed. This is achieved by heating above and then gradually cooling to room temperature with a magnetic field applied.

[0005]

As shown in FIG. 1 (a), the magnetoresistive effect element can be made into a single magnetic domain by completely aligning the magnetization direction in the element by applying an external magnetic field originally oriented in the easy magnetization direction. .. However, when an external magnetic field is applied in a direction opposite to this by 180 degrees, there arises a problem that the magnetization directions in the element are dispersed in fine units, as shown in FIG. Also, when an external magnetic field is applied in a direction deviating from the original easy magnetization direction by 0 degree or 180 degrees,
As shown in FIG. 1C, the inside of the element is divided into many magnetic domains. As shown in FIGS. 1B and 1C, when the magnetization directions in the element are dispersed, there is a problem in that Barkhausen noise that causes waveform distortion during a reproducing operation is generated. In order to secure stable reproduction characteristics without generating noise, it is first necessary to align the magnetization directions in the element as shown in FIG. Further, in order to stabilize the reproducing characteristic, it is effective to make the magnetization change in the magnetoresistive effect element less likely to occur, and therefore, the exchange coupling film is used. When the exchange-coupling film is heated above the Curie point, as shown in FIG.
The magnetization direction comes to face the direction of applying the external magnetic field. Here, when the temperature is gradually lowered to room temperature as shown in FIG. 2B, the magnetization directions in the exchange coupling film alternate with the film thickness direction, and at the boundary with the magnetoresistive effect element. It functions to fix the magnetization in the magnetoresistive effect element in the direction opposite to that of the magnetoresistive effect element. However, in this case, if the initial magnetization state in the magnetoresistive element is disturbed, the effect of reducing Barkhausen noise is lost. Therefore, in order to obtain stable reproduction characteristics, after the wafer process or the machining process, the head element is heated to the Curie point of the exchange coupling film or higher in an atmosphere in which an external magnetic field in the same direction as the easy magnetization direction of the magnetoresistive element is applied. After that, it is necessary to gradually cool to room temperature while applying a magnetic field.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 3 is a view of the vicinity of the magnetic sensitive portion of the double-sided shield type shunt bias type magnetoresistive head manufactured according to the present invention, as viewed from the medium facing surface. As the shield film 10, a Co type amorphous alloy film having a thickness of 1 μm and excellent in flatness is used. The ultrathin insulating layer 11 is an alumina film. The magnetoresistive effect element 12 is permalloy and has a film thickness of 15 nm or less. On the permalloy, an FeMn 13 having a film thickness of 40 nm and a Nb shunt film 14 having a film thickness of 30 nm having Curie points around 160 ° C. are formed as exchange coupling films. In this embodiment, the FeMn film is formed on the entire surface of the magnetoresistive effect element, but it is not always necessary to form it on the entire surface. The track width of the magnetoresistive head is defined by the distance between the pair of Cu lead wires 15, and this distance is 1 μm. The distance between the pair of shield layers is 0.25.
μm or less. The results of investigating the change in the reproducing characteristic by heat-treating this head in a magnetic field after the chip processing is described below.

FIG. 4 shows the result of monitoring the temperature change during the heat treatment. The temperature is raised at a rate of about 10 ° C./minute, and when the element temperature reaches 200 ° C., it is held here for 30 minutes. After that, the material was gradually cooled at a rate of about 4 ° C / minute. Note that this heat treatment is performed in a nitrogen atmosphere. FIG. 5 shows the relationship between the applied direction of the external magnetic field during the heat treatment and the measured reproduced waveform. This measurement was performed using a sputter medium and setting the recording density to 1 KFCI. The spacing between the head media is 0.05 μm. The magnetic field applied from the outside is a DC magnetic field having a magnitude of 1 KOe. From the results shown in FIG. 5, it can be seen that stable reproduction characteristics without reproduction distortion can be obtained by aligning the direction of application of the external magnetic field with the easy magnetization direction of the magnetoresistive effect element. Next, FIG. 6 shows the result of measurement of how the reproduced waveform distortion changes depending on the magnitude of the DC magnetic field applied from the outside. In this measurement, when the operation of returning the sense current from the optimum value in which the amplitude values of the upper and lower pulses are symmetrical to zero to 100 times is repeated, the number of times the reproduced waveform is distorted is expressed as a percentage. The measurement was performed using six heads. From these results, it was found that the reproduced waveform distortion factor could be suppressed to 5% or less by setting the external magnetic field strength to 1 KOe, which is not a practical problem.

[0008]

According to the present invention, it is possible to realize a magnetoresistive head having no reproduced waveform distortion.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a magnetized state in a magnetoresistive effect element.

FIG. 2 is an explanatory diagram of a magnetization state in an exchange coupling film.

FIG. 3 is a cross-sectional view of the magnetic sensing part of the magnetic head according to the present invention as viewed from the sliding surface side.

FIG. 4 is an explanatory diagram of a change in element temperature over time when performing heat treatment according to an example of the present invention.

FIG. 5 is an explanatory diagram of effects of the present invention.

FIG. 6 is a characteristic diagram showing a relationship between applied magnetic field strength and reproduced waveform distortion when performing heat treatment in a magnetic field according to the present invention.

[Explanation of symbols]

10 ... Shield film, 11 ... Insulating layer, 12 ... Magnetoresistive effect element, 13 ... Exchange coupling film, 14 ... Shunt film, 15 ... Lead wire.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yuu Yuto 1-280 Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Inventor Naoki Koyama 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. (72) Inventor Masahiro Kitada 1-280, Higashi Koikekubo, Kokubunji, Tokyo Hitachi, Ltd. Central Research Center (72) Inventor Ryoichi Nakatani, 1-280, Higashi Koikeku, Tokyo Kokubunji City

Claims (8)

[Claims] 1. A magnetoresistive head in which an antiferromagnetic film that causes magnetic exchange coupling with the magnetoresistive element is formed on at least a part of the magnetoresistive element. After the film is formed, it is once heated to a temperature equal to or higher than the Curie point of the antiferromagnetic film in the state where an external magnetic field in the same direction as the easy magnetization direction of the magnetoresistive element is applied, and then gradually cooled to room temperature. A method of manufacturing a magnetoresistive effect head, comprising: 2. The magnetic resistance according to claim 1, wherein the easy magnetization direction of the magnetoresistive effect element is determined by an application direction of an external magnetic field applied when the magnetoresistive effect element is formed by a vapor deposition method or a sputtering method. Method of manufacturing effective head. 3. The anti-strong magnetic field according to claim 1, wherein an external magnetic field in the same direction as a magnetic field applied when forming the magnetoresistive effect element causes exchange coupling with the magnetoresistive effect element. A method of manufacturing a magnetoresistive head that is also applied when forming a magnetic film. 4. The antiferromagnetic film which causes exchange coupling with the magnetoresistive effect element according to claim 1, wherein Fe and Mn are used.
A method of manufacturing a magnetoresistive head which is an alloy film containing as a main component. 5. The method of manufacturing a magnetoresistive head according to claim 1, wherein the heat treatment in a magnetic field is performed after the completion of all wafer processes. 6. The heat treatment in a magnetic field according to claim 1,
A method of manufacturing a magnetoresistive head after polishing a sliding surface. 7. The method for manufacturing a magnetoresistive head according to claim 1, wherein the magnetic field applied in the easy magnetization direction of the magnetoresistive element is 1 KOe or more. 8. A method of manufacturing a magnetoresistive head according to claim 1, wherein the easy magnetization direction of the magnetoresistive effect element is the track width direction.