JP2833586B2 - Magnetoresistive element and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head (hereinafter, referred to as "MR head"), and more particularly, to a magnetic recording medium such as a magnetic disk device or a magnetic tape device which records data on a magnetic recording medium. The present invention relates to a magneto-resistance effect element (hereinafter, referred to as “MR element”) in an MR head that reads out magnetization information using the magneto-resistance effect.

[0002]

2. Description of the Related Art An MR element is an element for detecting information by utilizing the fact that resistance changes depending on the angle between the direction of magnetization and the direction of sense current, and has high sensitivity to changes in magnetic field. From the magnetic recording device. As a material having a magnetoresistance effect, a soft magnetic material such as NiFe is used.

In order to use NiFe as an efficient read head that exhibits linear response to magnetic information written on a magnetic recording medium, an angle between a sense current flowing through NiFe and a magnetization direction of NiFe (hereinafter, referred to as NiFe). , "Bias angle") at a predetermined value (preferably 45 degrees). Various techniques have been disclosed as such bias means. Among them, in the MR head disclosed in Japanese Utility Model Application No. 59-48201, a non-magnetic conductor is provided on a soft magnetic lateral bias layer. Layer and a magnetoresistive layer (hereinafter referred to as “MR
Layer. ) Are sequentially stacked, a good bias angle is obtained, and an MR head excellent in linear response can be realized.

For example, a magnetic domain control film 28 as shown in FIG.
In a general shield type MR head having the MR layers 1 and 282, the sense current flows from the electrode films 291 and 292 to the MR layer 2
7, the current is shunted to the non-magnetic conductor layer 26 and the soft magnetic lateral bias layer 25. Therefore, in such a structure, the sense current shunted to the MR layer 27 and the non-magnetic conductor layer 26 causes the magnetic field passing in the plane of the soft magnetic lateral bias layer 25 and perpendicular to the direction of the sense current. Is generated, and the magnetization direction of the soft magnetic lateral bias layer 25 is rotated by this magnetic field. Therefore, the soft magnetic lateral bias layer 25 magnetized in a direction perpendicular to the direction of the sense current generates a magnetic field around the soft magnetic material lateral bias layer 25, and a part of the magnetic field is applied to the MR layer 27. On the other hand, the sense current shunted to the soft magnetic lateral bias layer 25 and the nonmagnetic conductor layer 26 generates a magnetic field that passes through the plane of the MR layer 27 and is perpendicular to the direction of the sense current.
The direction of this magnetic field coincides with the direction of the magnetic field generated by the magnetization of the soft magnetic lateral bias layer 25 described above. That is, a magnetic field generated by the magnetization of the soft magnetic lateral bias layer 25 and a magnetic field generated by the sense current are applied to the MR layer 27 as a bias magnetic field. This bias magnetic field rotates the magnetization of the MR layer 27 with respect to the sense current,
Is a predetermined value (ideally 45 degrees),
An MR head having excellent linear response is realized. Note that FIG.
In the shield type MR head described above, in addition to the above-described components,
A substrate 21, a substrate protective film 22, a first shield film 23, a first gap film 24, a second gap film 30, a second shield film 31, a protective film 32, and the like are provided.

[0005]

In the MR head having the above-mentioned structure (see FIG. 9), that is, a structure in which the soft magnetic lateral bias layer 25, the nonmagnetic conductor layer 26 and the MR layer 27 are laminated. In order to increase the output, the thickness of the soft magnetic lateral bias layer 25, the nonmagnetic conductor layer 26, and the MR layer 27 is being reduced. For example, MR
Conventionally, the thickness of the layer 27 is generally about 25 [nm] to 30 [nm]. However, the thickness is reduced to about 15 [nm] to 20 [nm] as the thickness of the layer 27 is reduced.
Accordingly, in order to apply an appropriate bias magnetic field to the MR layer 27, it is necessary to reduce the thickness of the soft magnetic lateral bias layer 25.

However, the conventional soft magnetic lateral bias layer 25
As shown in FIG. 10, when the film thickness becomes about 20 [nm], the saturation magnetic flux density (hereinafter, referred to as “B _s ”) rapidly decreases, and it becomes impossible to apply an appropriate bias magnetic field to the MR layer. To compensate for this, a method of increasing the film thickness is used, but this method has a problem in that the reproduction output of the head is reduced.

The reason will be described. The reproduction output (V) of the MR head is determined by the current (I) flowing through the MR layer 27 and M
It is represented by the product of the resistance change amount (△ R) of the R layer 27 (V = I × △ R). That is, V is proportional to I. On the other hand, I is defined by the sense current flowing through the electrode films 291 and 292, but the sense current from the electrode films 291 and 292 is not only transmitted to the MR film 27 but also to the soft magnetic lateral bias layer 25 and the non-magnetic conductive layer 26. Also diverts. The corresponding flow rate increases as the thickness of each film increases and the resistivity decreases. here,
When the thickness of the soft magnetic material lateral bias layer 25 is reduced, FIG.
Since B _s as shown in is reduced, it is inevitable to increase the thickness in order to compensate for this, also tends to decrease with increasing specific resistance of the film thickness. These actions combine to increase the current shunted to the soft magnetic lateral bias layer 25,
I of the MR film 27 decreases. That is, the reproduction output is reduced.

[0008] Another way to apply the appropriate bias magnetic field to the MR layer 27, there is a method of increasing the B _s of the soft magnetic transverse bias layer 25. Specifically, the method is to increase the addition amount of the ferromagnetic element in the soft magnetic lateral bias layer 25. However, if the addition amount of the ferromagnetic element is increased unnecessarily, the magnetization is saturated by the magnetic field due to the sense current. However, there is a problem that an appropriate bias magnetic field cannot be applied to the MR layer without causing such a problem, and noise is generated in the output waveform of the head.

The reason will be described. In order to increase the B _s of the soft magnetic transverse bias layer 25, the anisotropic magnetic field of the excessively increasing the amount of ferromagnetic element in the soft magnetic transverse bias layer 25 soft magnetic transverse bias layer 25 (Hereinafter, referred to as “H _k ”). as a result,
The magnetic field caused by I flowing in the MR layer 27 does not saturate the magnetization, so that an appropriate bias magnetic field cannot be applied to the MR layer 27. In addition, the coercive force in the hard axis direction (hereinafter, referred to as
"H _{c, h} ". ) Increases, and large magnetic hysteresis causes noise in the output waveform of the head.

[0010]

It is an object of the present invention to provide a large B _s (eg, 6500 [Gauss] or more), a small H _k (eg, 8 [Oe] or less) and a small H _{c, h} (eg, 0.5 [Oe] or less, it is possible to apply a stable and appropriate bias magnetic field to the MR film 27 even with a small film thickness, and furthermore, a soft magnetic material lateral bias that has a fast saturation of magnetization and does not cause noise in the output waveform of the head. An object of the present invention is to provide an MR element having a layer and a method for manufacturing the same.

[0011]

An MR element according to the present invention comprises a soft magnetic lateral bias layer, a non-magnetic conductor layer, and an MR layer. And the soft magnetic material lateral bias layer,
A laminate of a Ta layer and a CoZrMo layer (hereinafter referred to as “Ta / C
oZrMo ". ) Is a multilayer film having two or more constitutional units as one constitutional unit. CoZ in soft magnetic lateral bias film
The composition of rMo is, for example, Co _100-xy Zr _x Mo _y (3
≦ x ≦ 13) Within the range of [atomic percentage]. Further, a heat treatment is performed on the MR element at a temperature of 200 ° C. to 350 ° C. for 1 hour to 20 hours while applying an external magnetic field of 30 [Oe] or more, for example.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various characteristics of a soft magnetic lateral bias layer in an embodiment of an MR element according to the present invention will be described in detail.

First, a first Ta layer, a first CoZrMo layer, and a second Ta layer are formed on a glass substrate by sputtering.
Evaluation samples A, B, and C were formed by sequentially laminating the layer, the second CoZrMo layer, and the Ta layer with the layer thickness and the CoZrMo composition as shown in FIG. At this time, by applying a magnetic field of 75 [Oe] during film formation by sputtering,
Uniaxial magnetic anisotropy was imparted to the CoZrMo layer.

The sample A thus prepared is
For B and C, B _s and H were measured using a vibrating sample magnetometer.
_k , H _{c, h} and the coercive force in the easy axis direction (hereinafter referred to as “H
_{c, e} ". ) Was measured.

After the measurement, these samples were subjected to 8 × 10 ^-5 [P
a] Heat treatment was performed at 270 ° C. for 1 hour while applying an external magnetic field of 800 [Oe] in the easy axis direction in the following vacuum.
After the heat treatment, B _s , H _k , H _{c, h} and H _{c, e} were measured at the same time. FIG. 2 shows the results.

As shown in FIG. 2, the thickness of CoZrMo is 1
Even in the case of 0 [nm], B _s ≧ 6500 [Gauss] and H _k ≦ 8 [O] can be obtained by laminating a Ta film as a base and by performing a heat treatment in a magnetic field after the film formation.
e], the characteristics of H _{c, h} ≦ 0.5 [Oe] are realized. Heat treatment in a magnetic field has the effect of reducing _Hk and _{Hc, h} .

The soft magnetic material lateral bias layer is made of Ta / C.
Similar results were obtained as shown below not only in the case where oZrMo was used as one constitutional unit but also in the case where two constitutional units were used as described above.

A first method is performed on a glass substrate by sputtering.
Ta layer, the first CoZrMo layer, the second Ta layer, the second
CoZrMo layer, third Ta layer, third CoZrMo
The layer and the Ta layer have a layer thickness and CoZr as shown in FIG.
Samples for evaluation D were prepared by sequentially laminating films with the Mo composition. At this time, 750 [Oe] is used at the time of sputtering film formation.
A uniaxial magnetic anisotropy was imparted to the CoZrMo layer by applying the following magnetic field. Next, these samples were placed in an 8 × 1
550 in the easy axis direction in a vacuum of 0 ^-5 [Pa] or less.
Heat treatment was performed at 250 ° C. for 17 hours while applying an external magnetic field of [Oe].

With respect to the sample D thus prepared, B _s , H _k , H _{c, h} and H _{c, e} were measured using a vibrating sample magnetometer _, and the results were as shown in FIG. was gotten.

That is, as shown in FIG.
Even when the film thickness of o is 6.7 [nm] and the soft magnetic material lateral bias layer has three constituent units with Ta / CoZrMo as one constituent unit, B _s ≧ 6500 [Gauss] and H _k
It can be seen that the characteristics of ≦ 8 [Oe] and H _{c, h} ≦ 0.5 [Oe] are realized.

Samples A, B, C, and D were 8 × 10
550 [O] in the easy axis direction in a vacuum of ^-5 [Pa] or less.
e], heat treatment was performed at 400 ° C. for 1 hour while applying an external magnetic field, and H _{c, h} and H _{c, e} were measured with a vibrating sample magnetometer. This is because Hc _{, h} and Hc are changed by the structural change of the soft magnetic lateral bias layer.
_Since it is considered that _{c and e} increased, the heat treatment temperature was 3
It is desirable that the temperature be 50 ° C. or lower. Hc _{, h} and _{Hc, e also} increased when the heat treatment time exceeded 20 hours.

Next, as a comparative example, the case where the soft magnetic material lateral bias layer is only CoZrMo and the case where Ta / CoZrMo is 1
The characteristics in the case of only the structural unit will be described. A first Ta layer (or a Ta layer) is formed on a glass substrate by sputtering.
No layer), a first CoZrMo layer, and a Ta layer in this order.
Evaluation samples E, F, and G were produced with the layer thickness and the CoZrMo composition as shown in FIG. At this time, by applying a magnetic field of 75 [Oe] during sputtering film formation, Co
Uniaxial magnetic anisotropy was imparted to the ZrMo layer.

The sample E prepared in this way,
For F and G, B _s and H were measured using a vibrating sample magnetometer.
_k , H _{c, h} and H _{c, e} were measured. After the measurement, these samples were subjected to 270 in a vacuum of 8 × 10 ⁻⁵ [Pa] or less while applying an external magnetic field of 800 [Oe] in the easy axis direction.
Heat-treated at 1 ° C. for 1 hour After the heat treatment, B _s , H _k ,
H _{c, h} and H _{c, e} were measured. FIG. 6 shows the results.

[0024] From the results of FIG. 6, if Ta underlying film is not (sample E) decrease in H _k is not seen by heat treatment, such as when there is a first Ta film (Sample F, G), moreover the 1
It can be seen that H _{c, h} is larger than in the case where the Ta film is provided. That is, the first Ta film has an effect of reducing H _k by heat treatment and an effect of reducing H _{c, h} .

In the case where the soft magnetic material lateral bias layer is one structural unit of Ta / CoZrMo as in Samples F and G,
After heat treatment in a magnetic field, B _s ≧ 6500 [Gauss], H
_In order to realize all the characteristics of _k ≦ 8 [Oe] and H _{c, h} ≦ 0.5 [Oe], the soft magnetic material lateral bias layer is made of Ta / CoZr.
It is necessary to use Mo as one constituent unit to form a multilayer film of two or more constituent units.

Next, the composition of CoZrMo was changed to Co _100-xy
The reason for limiting to Zr _x Mo _y (3 ≦ x ≦ 5, 11 ≦ y ≦ 13) [atomic percentage] will be described. First, B _s is C
Since it depends on the amount of o and increases as the amount of o increases, B _s ≧
In order to realize the characteristics of 6500 [Gauss],
Preferably, CoZrMo is 82 [atomic percentage] or more. Further, since the H _k is smaller the larger the amount depends on the amount of Mo, in order to realize the characteristics of the H _k ≦ 8 [Oe] is the Mo in CoZrMo 11 [atomic%]
It is preferable to make the above. However, as the amount of Mo added increases, the Curie temperature decreases, and 13 [atomic percentage]
, The Curie temperature drops to about 300 ° C or less. Therefore, B _s also decreases, and B _s ≧ 65
00 [Gauss] cannot be realized. Therefore, the addition amount of Mo is preferably set to 11 to 13 [atomic percentage]. Further, H _{c, h} depends on the amount of Zr added, and when the amount is small, H _{c, h} increases. H _{c, h} ≦
In order to realize the characteristic of 0.5 [Oe], it is preferable that the addition amount of Zr is 3 [atomic percentage] or more.

Therefore, the composition of CoZrMo is Co
_{100-xy Zr x Mo y (} 3 ≦ x ≦ 5,11 ≦ y ≦ 13)
It is preferable to be within the range of [atomic percentage].

As described above, as the soft magnetic lateral bias layer, a multilayer film composed of two or more layer units using Ta / CoZrMo as one unit is used.
o _{100 -xy} Zr _x Mo _y (3 ≦ x ≦ 5, 11 ≦ y ≦ 1
3) By setting the composition within the range of [atomic percentage], even when the thickness of the soft magnetic lateral bias layer is reduced to 20 [nm] or less, a large B _s of 6500 [Gauss] or more is obtained.
And a soft magnetic lateral bias layer having a small H _{c, h} of 0.5 [Oe] or less.

The soft magnetic lateral bias layer may be
By performing a heat treatment for 1 hour to 20 hours at a temperature of 200 ° C. to 350 ° C. while applying an external magnetic field of [Oe] or more, the thickness of the soft magnetic lateral bias layer is 20 [nm] or less. Thus, a soft magnetic lateral bias layer having a small H _k of 8 “Oe” or less can be obtained.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 7, on a 1 μm-thick first shield film (not shown in FIG. 7) made of NiFe provided in advance on an Al ₂ O ₃ —TiC-based ceramic substrate. A gap film 1 made of Al ₂ O _{3 having} a thickness of 0.1 μm was prepared. Further, 1 [n
m], a first CoZrMo layer 3 having a thickness of 10 [nm], a second Ta layer 4 having a thickness of 1 [nm], and 10 [nm]. ], And a second CoZrMo layer 5 having a thickness of A non-magnetic conductor layer 6 having a thickness of 20 [nm] and an MR layer 7 having a thickness of 20 [nm] are further formed on the non-magnetic conductor layer 6 by a permanent magnet.
The film was formed under a uniform magnetic field of [Oe]. Although not shown in FIG. 7, 20
A magnetic domain control film made of an FeMn layer exhibiting antiferromagnetism with a thickness of [nm] and an electrode film made of Au with a thickness of 100 [nm] were provided. Then, the magnetic domain control film, the electrode film and M
A gap film made of Al ₂ O ₃ having a thickness of 0.1 μm and a _second film formed of NiFe having a thickness of 1 μm so as to cover the R layer 7.
And a protective film made of Al ₂ O ₃ having a thickness of 0.1 μm were laminated to form an MR element. Further, the MR element is placed in a vacuum of 8 × 10 ⁻⁵ [Pa] or less while applying an external magnetic field of 550 [Oe].
Heat treatment was performed at 70 ° C. for 1 hour.

Subsequently, the MR element was subjected to slider processing by a well-known technique, and at the same time, a pressure spring, a support arm and the like were attached, and wiring to electrodes was performed, thereby producing an MR head. When the reproduction characteristics of the MR head manufactured in this manner were examined, the magnetization of the soft magnetic lateral bias film 8 was saturated with a small sense current of 8 mA, and an appropriate bias magnetic field was applied to the MR layer 7. And a good reproduction characteristic without noise in the output waveform was obtained.

As another embodiment, as shown in FIG. 8, a 1 μm thick first shield film (not shown in FIG. 8) made of NiFe provided in advance on an Al ₂ O ₃ —TiC-based ceramic substrate. A) with a thickness of 0.1 μm
A gap film 10 made of l ₂ O ₃ was produced. Further, a first Ta having a thickness of 1 [nm] is formed by using a sputtering method.
Layer 11, a first CoZr having a thickness of 6.7 [nm]
Mo layer 12, second Ta layer 1 having a thickness of 1 [nm]
3, a second CoZrMo having a thickness of 6.7 [nm]
Layer 14, a third Ta layer 15 having a thickness of 1 [nm],
Third CoZrMo16 having a thickness of 6.7 [nm]
Were sequentially laminated. On top of that, a thickness of 10 [n]
m], a non-magnetic conductor 17 having a thickness of 20 [nm], and an MR layer 18 having a thickness of 20 [nm].
The film was formed under a uniform magnetic field of 75 [Oe] using a permanent magnet. Although not shown in FIG. 8, an N-layer having a thickness of 50 [nm] exhibiting antiferromagnetism is formed on both ends of the MR layer 18.
A magnetic domain control film made of an iMn layer and an electrode film made of Au having a thickness of 100 [nm] are arranged, and 0.1 μm thick Al _{2 is formed} so as to cover the magnetic domain control film, the electrodes and the MR layer 18.
A gap layer made of O _{3, a} second shield film made of NiFe having a thickness of 1 μm, and an Al ₂ O ₃ film having a thickness of 0.1 μm
An MR element was manufactured by laminating a protective film made of Further, this MR element is set to 8 × 10
Heat treatment was performed at 270 ° C. for 17 hours while applying an external magnetic field of 800 [Oe] in a vacuum of ⁻⁵ [Pa] or less.

Then, this MR element was subjected to slider processing by a well-known technique, and at the same time, a pressure spring, a support arm, etc. were attached and wiring to electrodes was performed to produce an MR head. When the reproduction characteristics of the MR head manufactured as described above were examined, the magnetization of the soft magnetic lateral bias film 19 was saturated with a small sense current of 8 mA, and the bias was applied to the MR layer 18 to apply an appropriate bias time. And a good reproduction characteristic without noise in the output waveform was obtained.

Although two embodiments suitable for the present invention have been described above, it goes without saying that various modifications other than this embodiment are possible within the scope of the present invention.

[0036]

As described above, by using the MR element and the method of manufacturing the same according to the present invention, a large B _s (for example, 6500 [Gauss]) can be obtained even at a small film thickness.
s] or more, and a soft magnetic lateral bias film having a small H _k (for example, 8 [Oe] or less) and a small H _{c, h} (for example, 0.5 [Oe] or less) can be obtained. Therefore, a stable and appropriate bias magnetic field can be applied to the MR film, and a small magnetic field generated by the sense current saturates the magnetization and has a small magnetic hysteresis, so that an MR element which does not cause noise in the output waveform of the head can be obtained. Can be

[Brief description of the drawings]

FIG. 1 shows an embodiment of an MR element according to the present invention.
4 is a chart showing the thickness and composition of a soft magnetic lateral bias layer.

FIG. 2 is a table showing measurement results of the MR element of FIG. 1;

FIG. 3 is a chart showing the thickness and composition of a soft magnetic lateral bias layer in another embodiment of the MR element according to the present invention.

FIG. 4 is a table showing measurement results of the MR element of FIG. 3;

FIG. 5 is a table showing the thickness and composition of a soft magnetic lateral bias layer in a comparative example of the MR element according to the present invention.

FIG. 6 is a table showing measurement results of the MR element of FIG. 5;

FIG. 7 is a sectional view showing an embodiment of an MR element according to the present invention.

FIG. 8 is a sectional view showing another embodiment of the MR element according to the present invention.

FIG. 9 is a sectional view showing a conventional MR element.

FIG. 10 is a graph showing the dependence of the saturation magnetic flux density on the thickness of the soft magnetic lateral bias layer in the conventional MR element.

[Explanation of symbols]

 1,10 Gap film 2,11 First Ta layer 3,12 First CoZrMo layer 4,13 Second Ta layer 5,14 Second CoZrMo layer 6,17,26 Nonmagnetic conductor layer 7,18 , 27 MR layer 8, 19, 25 Soft magnetic material lateral bias layer 9, 20 MR element 15 Third Ta layer 16 Third CoZrMo layer 21 Substrate 22 Substrate protective film 23 First shield film 24 First gap film Reference Signs List 30 second gap film 31 second shield film 32 protective film 281,282 magnetic domain control film 291,292 electrode film

Claims (3)

(57) [Claims] 1. A magnetoresistive element comprising a soft magnetic lateral bias layer, a non-magnetic conductor layer and a magnetoresistive layer, wherein the soft magnetic lateral bias layer is a laminate of a Ta layer and a CoZrMo layer. A magnetoresistance effect element comprising a multilayer film of two or more constituent units as one constituent unit. 2. CoZr in said soft magnetic lateral bias layer
When the composition of Mo is Co _100-xy Zr _x Mo _y (3 ≦ x ≦
5. The magnetoresistive element according to claim 1, wherein the value is within a range of 5, 11 ≦ y ≦ 13 [atomic percentage]. 3. The semiconductor device according to claim 1, wherein:
3. The method according to claim 1, wherein the heat treatment is performed at a temperature of 200 to 350.degree. C. for 1 to 20 hours while applying an external magnetic field of [Oe] or more. Method.