JP2001189505A - Manufacturing method for magneto-resistance effect thin-film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with a narrow gap by using a thinner film thickness. SOLUTION: An anti-ferromagnetic layer 7 of a spin valve film 1 is film- formed to a thickness equal to a critical film thickness which has been known. Then the anti-ferromagnetic layer 7 is thermally processed before etching. Thus, the entire film thickness of spin valve film 1 can be thinner while the switched connection magnetic field at the anti-ferromagnetic film 7 is held.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a magnetoresistive thin film including an underlayer, a first ferromagnetic layer, a nonmagnetic layer, a second ferromagnetic layer, and an antiferromagnetic layer. About the method.

[0002]

2. Description of the Related Art A magnetoresistive effect element (hereinafter, referred to as an MR element) is an element whose resistance value changes according to the magnitude of an external magnetic field. Is used as a magneto-sensitive element that detects A magnetic head using this MR element is generally called a magneto-resistance effect type magnetic head (hereinafter, referred to as an MR head).

[0003] The MR head is configured to read a magnetic signal recorded on the magnetic recording medium by utilizing the fact that the electric resistance of the MR element changes according to the signal magnetic field from the magnetic recording medium.

An MR head is an MR head formed as a thin film.
Since the track width is formed by the width of the element, it is easy to narrow the track, and the MR element is exposed from the surface facing the magnetic recording medium, so that the reproduction sensitivity is high. For this reason, it has attracted attention as an indispensable device for realizing high-density recording.

In recent years, there has been a demand for a magnetic recording medium having a small size and a large capacity, and accordingly, a high recording density of the magnetic recording medium has been increased by, for example, a method of narrowing the recording track width, that is, a narrow track. Is becoming more and more advanced.

For this reason, in the MR head, in order to prevent a decrease in signal output due to a narrow track of the magnetic recording medium, a conventionally used anisotropic magnetoresistance effect (AM) is used.
R: M using Anisotropic Magneto-Resistivity
Giant magnetoresistance effect (GMR: Giant Ma
Attention has been paid to using an MR element utilizing gneto-Resistivity.

An MR element utilizing the giant magnetoresistance effect is:
Since the rate of change in magnetoresistance is larger than that of an MR element utilizing the anisotropic magnetoresistance effect, it is suitable for narrowing the track.

As a film configuration of an MR element exhibiting a giant magnetoresistance effect, for example, a spin valve film has been proposed. The spin valve film includes a base layer, a first ferromagnetic layer (free layer), a nonmagnetic layer, a second ferromagnetic layer (pinned layer), and an antiferromagnetic layer sequentially stacked on a substrate. It has the structure which was done. In many cases, a protective layer is formed on the antiferromagnetic film.

In the spin valve film, the magnetization direction of the pinned layer is fixed by exchange coupling with the antiferromagnetic film, and the magnetization direction of the free layer rotates according to the signal magnetic field.

[0010]

The above-mentioned M
The R head is also used in a recording / reproducing device such as a hard disk device, but in such a recording / reproducing device, the gap width of the MR head becomes narrower as the recording density of the magnetic recording medium increases. In accordance with this, it is desirable to reduce the thickness of the spin valve film.

As described above, the spin-valve film is formed on the substrate by forming an underlayer, a first ferromagnetic layer (free layer), a nonmagnetic layer, a second ferromagnetic layer (pinned layer), It has a structure in which a ferromagnetic layer is sequentially stacked and a protective layer is further formed on an antiferromagnetic film, but the total thickness of the spin valve film is reduced while maintaining electrical and magnetic characteristics. To do this,
It is necessary to form the antiferromagnetic layer and the protective layer thin.

Among them, the thickness of the antiferromagnetic layer is thicker than other layers. In particular, when the antiferromagnetic layer is formed of an ordered antiferromagnetic material, the critical thickness is generally 25 nm.
The thickness is not less than 30 nm and is particularly thicker than other layers. Therefore, it is important to reduce the thickness of the antiferromagnetic layer in order to reduce the total thickness of the spin valve film.

The antiferromagnetic material forming the antiferromagnetic layer includes:
There are ordered antiferromagnetic materials and disordered antiferromagnetic materials.
Among them, the ordered antiferromagnetic material has a feature that the exchange coupling with the second ferromagnetic material is not weakened even when the temperature is increased as compared with the disordered antiferromagnetic material. Therefore, the antiferromagnetic layer is generally formed of a regular antiferromagnetic material.

As a method for forming a thin antiferromagnetic layer formed of an ordered antiferromagnetic material, for example,
A method of reducing the ultimate pressure has been proposed. (Shimizu et al., The Japan Society of Applied Magnetics, 23, No. 4-2, 104
5 (1999)) However, these methods are highly dependent on the film forming apparatus. For this reason, it has been difficult to reduce the thickness of the antiferromagnetic layer.

The present invention has been proposed in view of such a conventional situation, and has as its object to provide a method of manufacturing a thin magnetoresistive thin film.

[0016]

According to the present invention, there is provided a method of manufacturing a magnetoresistive thin film, comprising the steps of: forming a thin film;
And an etching step. In the thin film forming step, the underlayer, the first ferromagnetic layer, the nonmagnetic layer, the second ferromagnetic layer, and the antiferromagnetic layer are sequentially laminated to form a magnetic layer having a giant magnetoresistance effect. A resistance effect thin film is formed.
In the heat treatment step, heat treatment is performed on the magnetoresistive effect thin film. In the etching step, the antiferromagnetic layer is etched. Then, in the etching step,
By etching the antiferromagnetic layer,
The thickness of the magnetoresistive thin film is reduced.

Therefore, according to the method of manufacturing a magnetoresistive effect thin film according to the present invention, the thickness of the antiferromagnetic layer can be reduced. According to this manufacturing method, it is possible to provide a magnetoresistive thin film having a small total film thickness.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings used in the following description, in order to clearly illustrate the characteristics of each part, the characteristic parts may be enlarged and shown, and the dimensional ratio of each member is not the same as the actual one. Not exclusively.

In the following, the configuration, material, and the like of each thin film constituting the spin valve film 1 will be described. However, the present invention is not limited to the illustrated spin valve film 1, but has a desired purpose and What is necessary is just to select the composition and material of each thin film according to the performance.

First, the spin valve film 1 will be described.

As shown in FIG. 1, the spin valve film 1
An underlayer 3 and a first ferromagnetic layer (free layer) on a substrate 2
4, a nonmagnetic layer 5, a second ferromagnetic layer (pinned layer) 6,
The antiferromagnetic layer 7 and the protective layer 8 are sequentially laminated.

The substrate 2 is made of, for example, a non-magnetic non-conductive material such as glass.

The underlayer 3 is made of, for example, a non-magnetic non-conductive material such as Ta. Spin valve film 1
By providing the underlayer 3, the crystal orientation can be improved and the material of the substrate 2 can be suppressed from being contaminated.

The first ferromagnetic layer 4 is made of, for example, Ni--Fe
It is formed on the underlayer 3 by a magnetic material exhibiting good soft magnetic properties such as an alloy, a Co—Fe alloy, and a Co—Ni—Fe alloy. The first ferromagnetic layer is a so-called free layer, and its magnetization direction changes according to an external magnetic field. Further, the first ferromagnetic layer 4 includes, for example, a Ni—Fe alloy layer and a Co—Co alloy layer.
-It may be formed by a laminated structure with an Fe alloy layer.
With such a structure, it is possible to improve the reproduction sensitivity of the spin valve film 1.

The nonmagnetic layer 5 is made of, for example, Cu, Cu--Ni
It is formed on the first ferromagnetic layer 4 by a nonmagnetic material such as an alloy. The formation of the non-magnetic layer 5 causes a magnetostatic coupling between the first ferromagnetic layer 4 and the second ferromagnetic layer, so that a giant magnetoresistance effect appears in the spin valve film 1.

The second ferromagnetic layer 6, like the first ferromagnetic layer 4, is formed on the non-magnetic layer 5 by a magnetic material exhibiting good soft magnetic characteristics. The second nonmagnetic layer 6 is a so-called pinned layer, and its magnetization direction is fixed by exchange coupling with the antiferromagnetic layer 7.

The antiferromagnetic layer 7 is formed on the second ferromagnetic layer 6 by a regular antiferromagnetic material such as a Pt—Mn alloy, a Ni—Mn alloy, and a Pd—Pt—Mn alloy. I have. By forming the antiferromagnetic layer 7, the second
The magnetization direction of the ferromagnetic layer 6 is fixed. Antiferromagnetic layer 7
Is formed such that the film thickness is reduced by performing etching after forming the film, as described later.

It is desirable that the antiferromagnetic layer 7 be formed with a thickness of 5 nm or more and 25 nm or less. If the antiferromagnetic layer 7 is formed thinner than 5 nm, it becomes impossible to obtain an exchange coupling magnetic field sufficient for exchange coupling with the second ferromagnetic layer 6. The thickness of the antiferromagnetic layer is 25 nm.
When the spin valve film 1 is formed thicker, the film thickness of the spin valve film 1 does not decrease.

Further, as described above, since the antiferromagnetic layer 7 is formed of a regular antiferromagnetic material, the first ferromagnetic layer 4 and the second ferromagnetic layer 4 can be formed even when the temperature rises. The exchange coupling with 6 does not weaken.

The protective layer 8 is formed on the antiferromagnetic layer 7 with a nonmagnetic material such as Ta. By forming this protective layer 8, an increase in specific resistance of the spin valve film 1 can be prevented.

In the spin valve film 1, since the second ferromagnetic layer 6 is provided in contact with the antiferromagnetic layer 7, the second ferromagnetic layer 6 has an exchange coupling force acting between the second ferromagnetic layer 6 and the antiferromagnetic layer 7. The second ferromagnetic layer 6 is magnetized in a certain direction (hereinafter, such a second ferromagnetic layer 6 is referred to as a pinned layer). on the other hand,
Since the first ferromagnetic layer 4 is formed between the first ferromagnetic layer 4 and the second ferromagnetic layer 6 with the nonmagnetic layer 5 interposed therebetween, the magnetization direction easily rotates even with a weak external magnetic field ( Hereinafter, such a first ferromagnetic layer 4 is referred to as a free layer.)

The spin valve film 1 constructed as described above
When an external magnetic field is applied, the magnetization direction of the free layer is determined according to the direction and strength of the external magnetic field. The electrical resistance of the spin valve film 1 becomes maximum when the magnetization direction of the pinned layer and the magnetization direction of the free layer are 180 ° opposite to each other. The electrical resistance of the spin valve film 1 is minimized when the magnetization direction of the pinned layer is the same as the magnetization direction of the free layer.

Therefore, the electrical resistance of the spin valve film 1 changes according to the applied external magnetic field. The external magnetic field can be detected by reading the resistance change.

In the above description, the spin valve film 1 is provided on the substrate 2 with the underlayer 3 and the first ferromagnetic layer 4
, Non-magnetic layer 5, second ferromagnetic layer 6, anti-ferromagnetic layer 7
And the protective layer 8 are laminated in this order, but the present invention is not limited to such a configuration. For example, the second
The ferromagnetic layer 6 may have a laminated ferrimagnetic structure formed by sandwiching a nonmagnetic layer between two ferromagnetic layers.

Further, a dual type spin valve film 10 as shown in FIG. 2 may be used. The spin valve film 10
On a substrate 11, an underlayer 12 and a first antiferromagnetic layer 13
, A first ferromagnetic layer 14, a first nonmagnetic layer 15, a second ferromagnetic layer 16, a second nonmagnetic layer 17, a third ferromagnetic layer 18, a second An antiferromagnetic layer 19 and a protective layer 20 are stacked.

At this time, the first ferromagnetic layer 14 and the third ferromagnetic layer 18 are fixed magnetization layers (pin layers),
Is a magnetization free layer (free layer).

Since such a spin valve film 10 includes two magnetization fixed layers, the rate of change in resistance increases, and the reproduction sensitivity increases.

Next, a method of manufacturing the spin valve film 1 will be described.

First, each thin film layer constituting the spin valve film 1 is formed. Here, a method of forming each thin film layer using a DC magnetron sputtering apparatus will be described, but the method is not limited to this method. For example, each thin film layer constituting the spin valve film 1 may be formed by an evaporation method or the like. Further, each thin film layer constituting the spin valve film 1 may be formed by another sputtering method.

First, the substrate 2 is placed in a DC magnetron sputtering apparatus, and the inside of the DC magnetron sputtering apparatus is sufficiently reduced in pressure by a vacuum pump. In this embodiment, the pressure is set to 3 × 10 ⁻⁵ Pa or less. Then, Ar gas is introduced into the DC magnetron sputtering apparatus while adjusting the degree of vacuum. Thus, in the present embodiment, the pressure in the DC magnetron sputtering apparatus was set to 0.6 Pa. Further, a glass substrate was used as the substrate 2.

Next, on the substrate 2, an underlayer 3, a first ferromagnetic layer 4, a nonmagnetic layer 5, a second ferromagnetic layer 6, and an antiferromagnetic layer 7 are laminated in this order. did.

In the present embodiment, the underlayer 3
Was formed with Ta to a thickness of 5 nm. The first ferromagnetic layer 4 was formed by stacking NiFe having a thickness of 3.8 nm and CoFe having a thickness of 2 nm. Non-magnetic layer 5
Was formed with Cu to a thickness of 2.5 nm. The second ferromagnetic layer 6 was formed of CoFe with a thickness of 2.2 nm. The antiferromagnetic layer 7 was formed of PtMn with a thickness of 30 nm.

Next, a first heat treatment is performed. The first heat treatment is performed to set the magnetization direction of the second ferromagnetic layer 6. For this reason, in the first heat treatment, it is desirable that the applied magnetic field be a high magnetic field equal to or higher than the saturation magnetic field, and the temperature be higher than the temperature at which the antiferromagnetic layer 7 changes regularly. In the present embodiment, the temperature when applying a magnetic field is 250 ° C., the applied magnetic field is 2 kOe, and the holding time when applying a magnetic field is 4
Time. FIG. 3 shows the spin valve film 1 in this state. At this time, the magnetization direction of the first ferromagnetic layer 4 also
The magnetization direction is the same as that of the second ferromagnetic layer 6.

Next, a second heat treatment is performed. The second heat treatment changes the magnetization direction of the first ferromagnetic layer 4 to the second ferromagnetic layer 6.
This is performed so as to be orthogonal to the magnetization direction. The second heat treatment is
It is desirable that the condition be that only the magnetization direction of the second ferromagnetic layer 6 changes. For this reason, in the second heat treatment, it is preferable that the applied magnetic field be low and the temperature when the magnetic field is applied be low so that the magnetization direction of the second ferromagnetic layer does not change. In the present embodiment, the temperature is set to 220 ° C., and the applied magnetic field is set to 100 Oe.

As described above, by performing the first heat treatment and the second heat treatment, the magnetization directions of the first ferromagnetic layer 4 and the second ferromagnetic layer 6 can be made orthogonal. .
This makes it difficult for the spin valve film 1 to lose the vertical symmetry of the solitary wave in the reproduction signal.

Next, as shown in FIG. 4, the anti-ferromagnetic layer 7 was etched to remove the anti-ferromagnetic layer 7a shown in FIG. At this time, etching by ion milling is performed. By employing ion milling as an etching method, contamination to the antiferromagnetic layer 7 is less likely to occur.

The etching speed at this time is desirably 20 nm / min or less in consideration of the deterioration of the characteristics of the spin valve film 1 and the control of the film thickness during the etching. In this embodiment mode, the etching speed is set to 10 nm / min.

In this embodiment, Ar is used as the etching gas. However, it is also possible to use Xe as an etching gas, for example, to slow down the etching rate.

It has been found that in the spin valve film 1 in which the thickness of the antiferromagnetic layer 7 before etching is relatively large, ordered transformation of the antiferromagnetic layer 7 easily occurs. Therefore, a pin layer having small anisotropic dispersion can be formed. By subjecting the spin-valve film 1 to etching after the antiferromagnetic layer 7 is regularly transformed, the dispersion of anisotropy becomes smaller as compared with the conventional spin-valve film forming method.

The magnetization direction of the second ferromagnetic film 6 is slightly affected by the second heat treatment. However, here, before etching the antiferromagnetic film 7, the second
Heat treatment. Since the antiferromagnetic film 7 is formed thick at the time of performing the second heat treatment, the effect of the second heat treatment on the second ferromagnetic film is small.

Next, as shown in FIG. 5, a protective layer 8 is formed on the antiferromagnetic layer 7. In the present embodiment, the protective layer 8 is formed of Ta.

By etching the antiferromagnetic layer 7 as described above, the antiferromagnetic layer 7 can be formed thin. This makes it possible to reduce the thickness of the entire spin valve film 1. Then, the spin valve film 1 corresponding to the narrowing of the gap can be manufactured.

In order to prevent the antiferromagnetic layer 7 from being oxidized by the heat treatment, it is desired to form the protective layer 8 thick in the conventional method. However, in the spin valve film 1, since the oxide formed on the antiferromagnetic layer 7 by the heat treatment can be removed by etching, the protective layer 8 can be formed thin. As a result, the total thickness of the spin valve film 1 can be further reduced. In addition, the dispersion of the anisotropy is small as compared with the conventional spin valve film forming method.

Further, it is possible to prevent the sense current flowing in the spin valve film 1 from being shunted to the antiferromagnetic layer 7 and lost, and at the same time, the resistance change amount of the spin valve film 1 increases. For this reason, the MR head manufactured using the spin valve film 1 has an increased reproduction output.

FIGS. 6 and 7 show a magnetic head 40 manufactured using the spin valve film 1 manufactured by the above-described method.

As shown in FIG. 6, the magnetic head 40 has a substrate 41 on which a base layer 42 and a lower magnetic shield layer 43 are sequentially laminated. On the lower magnetic shield layer 43, a lower gap layer 44 is laminated. On the lower gap layer 44, the spin valve film 1, which is a magnetoresistive thin film, is formed.

In the longitudinal direction of the spin valve film 1, bias layers 45a and 45b and first electrode layers 46a and 46b are sequentially laminated. The spin valve film 1, the bias layers 45a and 45b, and the first electrode layers 46a and 46b are formed so as to be exposed on the sliding surface. Both ends of the spin valve film 1 are provided with a first electrode layer 46a and an electrode layer 46a.
b.

The spin valve film 1 and the bias layers 45a,
An intermediate gap layer 47 and an intermediate magnetic shield layer 48 are sequentially formed on the first electrode layer 45b and the first electrode layers 46a and 46b. An upper gap layer 49 is formed on the intermediate magnetic shield layer 48. Upper gap layer 49
On the upper side, a coil layer is formed in a spiral shape around the rear butting surface. An upper magnetic shield layer is formed on the coil layer.

Here, illustration of the coil layer, the rear butting surface, and the upper magnetic shield layer is omitted.

Spin valve film 1 in MR head 40
As shown in FIG. 7, a lower layer 3 and a first layer 3 are formed on a lower gap layer 44 formed on a lower magnetic shield layer 43.
, A non-magnetic layer 5, a second ferromagnetic layer 6,
It has a structure in which an antiferromagnetic layer 7 and a protective layer 8 are formed. In the longitudinal direction of the spin valve film 1 thus formed, the bias layers 45a, 45b and the electrode layers 46a, 4
6b are formed. Then, an intermediate gap layer 47 and an intermediate magnetic shield layer 48 are sequentially formed on the protective layer 8, the electrode layers 46a and 46b.

As is clear from the above description, the MR head 40 has a thinner spin valve film 1. Therefore, it is possible to cope with the narrowing of the gap. Further, since the thickness of the antiferromagnetic layer 7 in the spin valve film 1 is reduced, it is possible to prevent a current from being shunted to the antiferromagnetic layer 7 and to be lost. The amount of change increases. As a result, the MR head 40 has a high reproduction output.

As is clear from the above description, the spin-valve film 1 to which the present invention is applied is obtained by etching the antiferromagnetic layer 7 while maintaining the magnitude of the exchange coupling magnetic field. The thickness of the ferromagnetic layer 7 can be reduced. Thus, the thickness of the entire spin valve film 1 can be reduced, and the spin valve film 1 corresponding to a narrow gap can be provided.

In order to prevent the antiferromagnetic layer 7 from being oxidized by the heat treatment, it is desired to form the protective layer 8 thick in the conventional method. However, in the spin valve film 1, since the oxide formed on the antiferromagnetic layer 7 by the heat treatment can be removed by etching, the protective layer 8 can be formed thin. As a result, the total thickness of the spin valve film 1 can be further reduced.

Since the heat treatment is performed before the etching, the anisotropic dispersion in the antiferromagnetic layer 7 can be prevented. This makes it possible to prevent Barkhausen noise from being generated due to the thin antiferromagnetic film 7.

Further, it is possible to prevent the sense current flowing in the spin valve film 1 from being shunted to the antiferromagnetic layer 7 and to be lost, and at the same time, the resistance change amount in the spin valve film 1 increases. For this reason, the MR head 40 manufactured using the spin valve film 1 has a high reproduction output.

[0066]

Next, the relationship between the thickness of the antiferromagnetic layer in the spin valve film and the stability of the spin valve film will be described based on examples and comparative examples.

Example 1 An underlayer, a first ferromagnetic layer, a nonmagnetic layer,
After the second ferromagnetic layer and the antiferromagnetic layer are sequentially stacked by the high vacuum sputtering apparatus as described above, the antiferromagnetic layer is etched so that the thickness of the antiferromagnetic layer is different. A plurality of spin valve films were produced. The amount of etching performed on the antiferromagnetic layer in each spin valve film and the final thickness of the antiferromagnetic layer are as shown in Table 1 below.

[0068]

[Table 1]

For each spin valve film having a different thickness of the antiferromagnetic layer, the relationship between the thickness of the antiferromagnetic layer and the exchange coupling magnetic field and the relationship between the thickness of the antiferromagnetic layer and the amount of change in resistance were measured. did. Further, the relationship between the magnetic field and the magnetization was measured for a spin valve film having an antiferromagnetic layer with a thickness of 15 nm.

COMPARATIVE EXAMPLE 1 An underlayer, a first ferromagnetic layer, a non-magnetic layer,
As described above, the second ferromagnetic layer and the antiferromagnetic layer
A plurality of spin-valve films sequentially laminated by a high vacuum sputtering apparatus were produced. At this time, the thickness of the antiferromagnetic layer formed in each spin valve film is 15 n
m, 20 nm, 25 nm, and 30 nm.

The relationship between the thickness of the antiferromagnetic layer and the exchange coupling magnetic field was measured for each of the spin valve films having different thicknesses of the antiferromagnetic layer.

First, the relationship between the thickness of the antiferromagnetic layer and the coupling magnetic field in each of the spin valve films manufactured in Example 1 and Comparative Example 1 is shown in FIG.

FIG. 8 shows that in Example 1, the exchange coupling magnetic field hardly changed even when etching was performed. In particular, even when the thickness of the antiferromagnetic layer is set to 20 nm by performing etching of 10 nm, the exchange coupling magnetic field is 900 Oe
It was found that this was almost the same as the exchange coupling magnetic field of 950 Oe when no etching was performed. Further, even when the thickness of the antiferromagnetic film is set to 5 nm, 100O
It was found that there was a coupling magnetic field of e.

On the other hand, in Comparative Example 1, the exchange coupling magnetic field when the thickness of the antiferromagnetic film was 20 nm was reduced to 450 Oe, and the exchange coupling magnetic field when the thickness was 15 nm. Was found to decrease to 100 Oe.

From the above results, it is possible to reduce the thickness of the antiferromagnetic layer by etching after forming the antiferromagnetic layer with a thickness of 30 nm, which is the critical film thickness, thereby obtaining the exchange coupling in the antiferromagnetic layer. It has been found that the total thickness of the spin valve film can be reduced while maintaining the magnetic field.

Next, the relationship between the thickness of the antiferromagnetic layer and the amount of change in resistance for each of the spin valve films manufactured in Example 1 is shown in FIG.

FIG. 9 shows that the resistance change amount increases as the thickness of the antiferromagnetic layer is reduced. It was also found that the reproduction output increased with this. For example, when the thickness of the antiferromagnetic layer is 15 nm, the amount of change in resistance is 1.15 times that when the thickness of the antiferromagnetic layer is 30 nm. At this time, the reproduction output increases by about 15%.

As described above, the cause of the increase in the resistance change is considered to be that the amount of the sense current shunted to the antiferromagnetic layer decreases as the thickness of the antiferromagnetic layer decreases.

Next, FIG. 10 and FIG. 11 show the results of measuring the relationship between the magnetic field and the magnetization of the spin valve film manufactured in Example 1 having a thickness of 15 nm.
FIG. 10 shows a major loop, and FIG. 11 shows a minor loop. From FIGS. 10 and 11,
It turned out that neither the major loop nor the minor loop was almost the same as the conventional shape. This indicates that the coercive force does not change even when the thickness of the antiferromagnetic layer is reduced.

[0080]

As is clear from the above description, according to the method of manufacturing a magnetoresistive element according to the present invention, it is possible to provide a magnetoresistive element having a thin antiferromagnetic layer. Become. In addition, the protective layer can be formed thin. This makes it possible to reduce the thickness of the entire magnetoresistive thin film while maintaining the magnitudes of the exchange coupling magnetic field and the coercive force, and to provide a magnetoresistive thin film corresponding to a narrow gap. It becomes possible.

Further, anisotropic dispersion in the antiferromagnetic layer can be prevented. This makes it possible to provide a magnetoresistive thin film in which Barkhausen noise is less generated due to the thin antiferromagnetic film.

Further, it is possible to prevent the sense current flowing in the magnetoresistive effect thin film from being shunted to the antiferromagnetic layer and lost, and to provide a magnetoresistive effect thin film having a large resistance change amount. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a spin valve film manufactured by applying the present invention.

FIG. 2 is a cross-sectional view of a dual type spin valve film manufactured by applying the present invention.

FIG. 3 is a view for explaining a manufacturing process of the spin valve film, and is a cross-sectional view showing a state before the antiferromagnetic layer is etched.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of the spin valve film, showing a state after the antiferromagnetic layer is etched.

FIG. 5 is a diagram illustrating a manufacturing process of the spin valve film, and is a cross-sectional view illustrating a state where a protective layer is formed after the antiferromagnetic layer is etched.

FIG. 6 is a schematic perspective view showing an MR head manufactured using the spin valve film.

FIG. 7 is an enlarged view of a portion A in FIG. 6;

FIG. 8 shows a film thickness of an antiferromagnetic layer in the spin valve film and a spin valve film manufactured by a conventional manufacturing method;
FIG. 4 is a diagram illustrating a relationship between an antiferromagnetic layer and a coupling magnetic field.

FIG. 9 is a diagram showing a relationship between the thickness of the antiferromagnetic layer in the spin valve film and the resistance change amount.

FIG. 10 is a diagram showing a major loop in a relationship between a magnetic field and magnetization in the spin valve film.

FIG. 11 is a diagram showing a minor loop in a relationship between a magnetic field and magnetization in the spin valve film.

[Explanation of symbols]

Reference Signs List 1 spin valve film, 3 underlayer, 4 first ferromagnetic layer, 5 nonmagnetic layer, 6 second ferromagnetic layer, 7 antiferromagnetic layer, 43 lower magnetic shield layer, 44 lower gap layer, 45 bias layer , 46 electrode layer, 47 intermediate gap layer, 48 intermediate magnetic shield layer

Claims (6)

[Claims] 1. A magnetoresistive device having a giant magnetoresistive effect by sequentially laminating an underlayer, a first ferromagnetic layer, a nonmagnetic layer, a second ferromagnetic layer, and an antiferromagnetic layer. A thin film forming step of forming an effect thin film, a heat treatment step of performing a heat treatment on the magnetoresistive effect thin film, and etching of the antiferromagnetic layer,
A method for producing a magnetoresistive thin film, comprising an etching step for reducing the thickness of the magnetoresistive thin film. 2. The method according to claim 1, wherein the antiferromagnetic layer is formed of a regular antiferromagnetic material. 3. The method of manufacturing a magnetoresistive thin film according to claim 1, further comprising a protective layer forming step of laminating a protective layer on said magnetoresistive effect thin film after said etching step. 4. The method according to claim 1, wherein in the thin film forming step, the antiferromagnetic layer is formed to have a thickness of 5 nm or more and less than 25 nm. 5. The heat treatment step includes: a first heat treatment step of applying a heat treatment to the magnetoresistive thin film while applying a magnetic field in a first direction; and the magnetic treatment while applying a magnetic field in a second direction. And a second heat treatment step of performing a heat treatment on the resistance effect thin film. In the first heat treatment step, a higher temperature heat treatment is performed on the magnetoresistive thin film than in the second heat treatment step. 2. The method according to claim 1, wherein a larger magnetic field is applied than in the second heat treatment step. 6. The method according to claim 1, wherein in the etching step, the antiferromagnetic layer is etched by an ion milling method.