JPH11329883A - Manufacture of magnetoresistive effect film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a magnetoresistive effect film where a large exchange coupling magnetic field can be obtained. SOLUTION: Ferromagnetic layers 2 and 4 are laminated on a board confronting each other through the intermediary of a non-magnetic layer 3, and an antiferromagnetic layer 5 is provided adjacent to the ferromagnetic layer 4 for the manufacture of a magnetoresistive effect film, wherein a sputtering operation is carried out on the board by the use of an Al or an Si target applying an AC voltage. Then, a magnetoresistive effect film 10 is formed on the board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic layer which is provided on a substrate and is stacked opposite to each other via a nonmagnetic layer of Cu or the like. More particularly, the present invention relates to a method for manufacturing a magnetoresistive film having a large exchange coupling magnetic field.

[0002]

2. Description of the Related Art Technological innovations in the field of magnetic recording are remarkable. Taking the recording density as an example, a high growth rate of about 60% per year has been achieved over the last decade or so. In addition, it is expected that this growth rate will continue. The magnetic head is a recording / reproducing separation type head using an anisotropic magnetoresistive film as a detecting element at a magnetic recording density exceeding about 1 Gbit / in ^2.
R heads are rapidly being applied. However, as the recording density increases to 3 to 4 Gbit / in ² or more, there is a concern that this type of MR head will have a shortage of reproduction output, and a magnetic head based on a new principle has been developed.

As one of the approaches, increasing the sensitivity of the anisotropic magnetoresistive film forming the detecting element of the MR head is considered to be the shortest method. According to the prior art, the rate of change of the magnetoresistance of the anisotropic magnetoresistive film is at most 2 to 3%. However, the current material and composition have reached a limit in increasing the rate of change to several times at a stroke. . Also, it is expected that a great deal of time and effort will be required to develop new materials. However, it has recently been reported that a combination of a ferromagnetic and antiferromagnetic thin film can provide an unprecedented large magnetoresistance effect, and research and development in this area has been activated.
Currently, the most noticeable is the spin valve film using the giant magnetoresistance effect, which is considered to be the most promising.
Consideration for practical use as a detection element of an MR head has begun.

[0004] Generally, a spin valve film is formed by stacking a first ferromagnetic layer (free layer), a nonmagnetic layer, a second ferromagnetic layer (fixed layer), and an antiferromagnetic layer on a substrate in this order. It has a structure. Such a multi-layered spin valve film has a nonmagnetic layer interposed between the first and second ferromagnetic layers, and an antiferromagnetic layer is adhered to one of the ferromagnetic layers. It is. In this configuration, a giant magnetoresistance effect is developed between the first and second ferromagnetic layers by bringing the antiferromagnetic layer into close contact with the second ferromagnetic layer. The giant magnetoresistance effect is based on the fact that the relative angle of magnetization between the first and second ferromagnetic layers separated by the non-magnetic layer depends on the external magnetic field strength when an externally applied magnetic field is applied. And the electrical resistance increases or decreases as a result. The rate of change of the electric resistance of the spin valve film, that is, the sensitivity, is higher than the anisotropic magnetoresistance effect of the NiFe film, and is 7-8.
% Has been reported. In addition, by using a NiFe alloy or a Co-based alloy having excellent soft magnetic properties for the first ferromagnetic layer (free layer), the signal magnetic field from the magnetic recording medium is sufficiently large even with a weak magnetic field of 20 to 30 Oe. The change rate of the magnetoresistance can be obtained.

Further, when a very thin antiferromagnetic layer is provided adjacent to the ferromagnetic layer, an exchange coupling action occurs, and the direction of magnetization of the ferromagnetic layer is fixed. The magnetic field generated by this exchange coupling action is a unidirectional anisotropic magnetic field called exchange coupling magnetic field Hex. The stronger the exchange coupling action, that is, the higher the exchange coupling magnetic field Hex, the better the characteristics of the spin valve film.

As an antiferromagnetic layer, an iron-manganese alloy film described in JP-A-2-61572,
A nickel-manganese alloy film and the like described in Japanese Patent Publication No. 7 are known, but these have problems in material. The following five characteristics are required for the antiferromagnetic material used in the magnetic recording / reproducing apparatus. (1) Large coupling magnetic field (2) 1
Maintains characteristics against temperature rise of 50 ° C or more (3) 5
(4) not requiring a complicated anisotropic process, for example, a long-time heat treatment, and (5) sufficient corrosion resistance to an exposed environment, which exhibits properties with a thin film having a thickness of 0 nm or less. In view of the above items, the above-mentioned materials have not been able to solve the material problems regarding temperature characteristics, corrosion resistance, simplicity of the process, and the like. Such a problem has made it extremely difficult to realize a magnetic recording / reproducing apparatus with a high recording density, particularly to realize the reliability of the apparatus.

[0007]

SUMMARY OF THE INVENTION
Cr _30-70 Mn _30-70 P disclosed in JP 9-16923
An antiferromagnetic material having excellent corrosion resistance and temperature characteristics was found in a t _3-30 (atomic%) alloy thin film. However, the remaining problem is the large coupling magnetic field of the above (1). According to a known example, a sufficient exchange coupling magnetic field cannot be obtained unless the thickness of the CrMnPt film is increased to 30 nm or more. Further, since the magnetoresistive effect film may reach a high temperature of 180 to 200 [deg.] C. in its use state, it is necessary to have a sufficiently large exchange coupling magnetic field even at that temperature. Therefore, the exchange coupling magnetic field of the CrMnPt alloy can be further improved, and even if the exchange coupling magnetic field is large even at a high temperature, the film thickness can be reduced, and good spin valve characteristics can be obtained.

Accordingly, it is an object of the present invention to provide a method of manufacturing a magnetoresistive film capable of obtaining an unprecedented large exchange coupling magnetic field.

[0009]

According to the present invention, there is provided a method of manufacturing a magnetoresistive film, wherein one of ferromagnetic layers provided on a substrate and opposed to each other with a nonmagnetic layer interposed therebetween. In the case where an antiferromagnetic material layer is provided adjacent to the ferromagnetic material layer, sputtering is performed by applying an AC voltage to the substrate using an Al or Si target, and then the magnetoresistance effect is formed on the substrate. The method is characterized in that a film is formed.

When sputtering is performed by applying an AC voltage using the Al or Si target, Ar and O _{2 are used.}
Is preferably introduced by introducing a mixed gas of In the present invention, the antiferromagnetic layer provided adjacent to the ferromagnetic layer is preferably a CrMnPt alloy or an IrMn alloy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A reproducing section of a magnetic head using a magnetoresistive film to which the present invention is applied has a structure as shown in FIG. That is, the lower shield film 8, the gap alumina film 9, the magnetoresistive film 10, the gap alumina film 11, and the upper shield film 12 are formed on the substrate in this order. Therefore, the magnetoresistive film 10 is formed on the alumina film. As shown in FIG. 2, a magnetoresistive film 10 is formed on a gap alumina film 9 on a base film layer 1 such as Ta, a first ferromagnetic layer (free layer) 2, a nonmagnetic layer 3, and a second It has a basic structure in which a ferromagnetic layer (fixed layer) 4, an antiferromagnetic layer 5, and a protective film layer 6 such as Ta are laminated.

The magnetoresistive film 10 has a 5 nm thick T
a Underlayer 1, 5 nm thick first ferromagnetic layer (free layer) made of Ni ₈₁ Fe ₁₉ alloy 2, 3 nm thick nonmagnetic layer 3, 2.5 nm thick Co The ferromagnetic layer (fixed layer) 4 of the above, and an antiferromagnetic layer 5 made of a CrMnPt alloy having a thickness of 30 to 40 nm can be obtained.

In this magnetoresistive effect film 10, a CrMnPt alloy having good corrosion resistance is used as the antiferromagnetic layer 5, and the adjacent ferromagnetic layer 4 is made of Co or a Co alloy. formula Cr _x Mn _y the composition of the
It consists of an alloy represented by Pt _z (x, y, z: atomic%),
X, y, z are 32 ≦ x ≦ 50, 36 ≦ y ≦ 53, 11 ≦
By satisfying z ≦ 17, x + y + z = 100, a spin-valve magnetoresistive film with a large exchange coupling magnetic field and high thermal stability is realized, resulting in good sensitivity and reliability. Thus, a magnetic head having a magnetoresistive film having the above characteristics can be obtained. It is preferable that the thickness of the second ferromagnetic layer 4 adjacent to the antiferromagnetic layer 5 be 2 to 3.5 nm.

The method of manufacturing the magnetoresistive film according to the present invention is as follows.
(Angstrom) A substrate with a thick film is used. After transferring the substrate to the sputtering chamber, the substrate was evacuated to 3 × 10 ⁻⁷ Torr, and then Ar gas was supplied at 30 sccm and oxygen gas was supplied at 20 sc.
It was introduced into the chamber at a flow rate of sccm. AC power of 100 W was applied to an Al target provided in the chamber, and discharge was performed for 20 seconds to 2 minutes. After evacuation was performed for 3 minutes after the discharge was completed, a magnetoresistive film 10 was formed as follows. The film constituting the magnetoresistive film 10 was manufactured by DC magnetron sputtering as follows. The following materials were sequentially laminated in an atmosphere of 3 mTorr to 9 mTorr of argon. Tantalum, nickel-19wt% iron alloy as sputtering target,
Copper, cobalt and chromium-manganese-platinum targets were used.

The magnetoresistive film was formed by applying a high voltage to each of the cathodes on which the respective targets were arranged, generating plasma in the apparatus, and sequentially forming each layer. At the time of film formation, a magnetic field of about 70 Oe was applied in parallel to the substrate using a permanent magnet to impart uniaxial anisotropy, and the direction of the exchange coupling magnetic field of the chromium-manganese-platinum film was guided in the direction of the applied magnetic field.
Table 1 shows the conditions for forming each layer.

[0016]

[Table 1]

After the formation of the magnetoresistive film 10, a heat treatment was performed in a vacuum heat treatment apparatus. The heat treatment was performed by increasing the temperature from room temperature to a predetermined temperature, for example, 230 ° C., holding for a predetermined time, for example, 3 hours, and cooling to room temperature. In all of the steps of temperature increase, holding, and cooling, a magnetic field of 3 kOe was applied in parallel to the plane of the substrate. The direction of the magnetic field was parallel to the magnetic field applied by the permanent magnet during film formation.

[0018]

EXAMPLES In forming a magnetoresistive film according to the present invention, the effect of the surface treatment conditions of the substrate before film formation on the exchange coupling magnetic field Hex was examined. Table 2 shows the results.
Using a substrate on which an alumina film was formed to a thickness of 800 A, as a surface treatment, evacuated to 3 × 10 ⁻⁷ Torr, then introduced Ar gas at a flow rate of 30 sccm and oxygen gas at a flow rate of 20 sccm into the sputtering chamber. AC power of 100 to 200 W was applied to the provided Al target, and discharge was performed for 30 seconds to 3 minutes. Table 2 shows that the magnetoresistive film was formed after the discharge was completed in the same manner as described above.
This is an embodiment. Using the same substrate as the surface treatment of the substrate by a conventional ion milling method, and then forming a magnetoresistive film as a comparative example. As is clear from Table 2, according to the present invention, the exchange coupling magnetic field could be increased as compared with the conventional example.

[0019]

[Table 2]

[0020]

As described above, according to the method of manufacturing a magnetoresistive effect film of the present invention, a larger exchange coupling magnetic field can be obtained than in the prior art. As described above, according to the present invention, since the magnetoresistive film has a large exchange coupling magnetic field, good spin valve characteristics can be obtained, and a high-output magnetic recording head having stable characteristics can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic view of a reproducing section of a magnetic head to which a magnetoresistive film of the present invention is applied.

FIG. 2 is a schematic view of one embodiment of the magnetoresistive film of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base film layer 2 first ferromagnetic layer (free layer) 3 nonmagnetic layer 4 second ferromagnetic layer (fixed layer) 5 antiferromagnetic layer 6 protective film layer 8 lower shield film 9, 11 gap Alumina film 10 Magnetoresistive film 12 Upper shield film

Claims (3)

[Claims] An antiferromagnetic layer is provided adjacent to one of the ferromagnetic layers provided on a substrate and opposed to each other with a nonmagnetic layer interposed therebetween. A method of manufacturing a magnetoresistive film, wherein an AC voltage is applied to the substrate by sputtering using an Al or Si target, and then a magnetoresistive film is formed on the substrate. Manufacturing method of resistive effect film. 2. A magnetoresistive effect according to claim 1, wherein a sputtering is performed by introducing a mixed gas of Ar and O ₂ when applying an AC voltage using said Al or Si target and performing sputtering. Manufacturing method of membrane. 3. The method according to claim 1, wherein the antiferromagnetic layer provided adjacent to the ferromagnetic layer is a CrMnPt alloy or an IrMn alloy.