JP2006237154A - Magnetoresistive element and magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetoresistive effect element that does not increase noise easily even if allowing current to flow, and can obtain a satisfactory S/N ratio, and to provide a magnetic head using the magnetoresistive effect element. <P>SOLUTION: In the magnetoresistive effect element 10, a laminated film, which has at least a magnetized fixed layer 21, a non-magnetic layer 16, and a magnetized free layer 17, is formed, current is allowed to flow in a direction nearly vertical to the surface of the laminated film, and a conductive layer 18, which uses at least one type selected from Pd, Pt, Nd, Sm, Tb, Dy and Ho as a main component, is provided near the magnetized free layer 17. The magnetic head has the magnetoresistive effect element 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetoresistive effect element using a magnetic tunnel effect element or a giant magnetoresistive effect element, and a magnetic head using the magnetoresistive effect element, and is suitable for application to a reproducing magnetic head.

  In a magnetic reproducing head for a hard disk device, a magnetoresistive element is generally used to obtain a high output.

  In order to improve the recording density and the recording procedure of the disk device, it is necessary to increase the reproduction output of the magnetic reproducing head. For this purpose, a magnetoresistive element having a large magnetoresistive effect (MR effect) is required. .

  The magnetoresistive effect element for the magnetic head includes an anisotropic magnetoresistive effect element (AMR element) using a NiFe alloy, a giant magnetoresistive effect element (GMR element) having a spin valve structure, and a tunnel magnetoresistive effect. The tunnel magnetoresistive effect element (TMR element) used has been developed, and the magnetoresistance change rate (MR ratio) representing the output of the element is 2 to 3%, 5 to 20%, and 50 to 200%, respectively. And the larger output can be expected for the latter element.

A schematic diagram (perspective view) of a magnetic head using a general GMR element is shown in FIG.
A magnetoresistive effect element 104 is formed by superposing a soft magnetic layer 102 and an insulating layer 103 serving as a lower layer shield on the surface of a substrate 101 such as an Altic serving as a slider, and is processed to have a track width on the insulating layer 103. And electrodes 105 and 106 connected to both ends thereof.
Further thereon, an insulating layer 107 serving as an upper gap and a soft magnetic layer 108 serving as an upper shield are formed.

In the signal detection of the magnetic head having this configuration, a change in resistance of the magnetoresistive effect element is detected by applying a voltage between the two electrodes 105 and 106 and detecting a flowing current. For this reason, it is called a current in-plane type (CIP type, abbreviation of Current In Plane) detection method.
In the current in-plane type (CIP type) magnetic head, an AMR element or a GMR element is used as the magnetoresistive element.

Next, a schematic diagram (perspective view) of a general magnetic head using a TMR element is shown in FIG.
A lower layer shield / lower electrode 112 is formed on the surface of a substrate 101 such as an Altic as a slider, and a conductor layer 114 serving as a lower gap / lower connection electrode is formed on the surface of the substrate. An effect element 115 is formed.
Further thereon, a conductor layer 116 serving as an upper gap and upper connection electrode and an upper shield and upper electrode 118 are formed.

The signal detection of the magnetic head having this configuration detects a change in resistance of the magnetoresistive effect element by applying a voltage between the lower layer shield / lower electrode 113 and the upper layer shield / upper electrode 118 and detecting a flowing current. To do. For this reason, it is called a current surface direct type (CPP type, abbreviation for Current Perpendicular to the Plane) detection method.
In the current surface direct type (CPP type) detection type magnetic head, a TMR element or a GMR element is used as a magnetoresistive effect element.

A typical film configuration of the TMR element is composed of, for example, a base layer / an antiferromagnetic layer / a magnetization fixed layer / a tunnel barrier layer (tunnel insulating layer) / a magnetization free layer / a cap layer from the lower layer. A configuration in which the film configuration is upside down is also possible.
When a TMR element is used for a magnetic head, a magnetic free layer is used for magnetic detection to detect a magnetic flux generated corresponding to information recorded on a recording medium or the like. That is, the magnetization free layer is a signal detection layer that detects a signal based on information recorded on a recording medium or the like.

Here, FIG. 5 shows an example of a schematic cross-sectional view of a laminated film of magnetoresistive effect elements made of TMR elements.
In this magnetoresistive effect element 50, a base layer 51, a magnetization fixed layer 61, a tunnel barrier layer (tunnel insulating layer) 56, a magnetization free layer (signal detection layer) 57, and a cap layer 58 are laminated on a substrate (not shown). ing. The magnetization fixed layer 61 includes an antiferromagnetic layer 52 and a laminated film of three layers of a ferromagnetic layer 53 / nonmagnetic conductor layer 54 / ferromagnetic layer 55 formed thereon.
In the magnetization fixed layer 61, the direction of the magnetization M 53 of the lower ferromagnetic layer 53 is fixed by the antiferromagnetic layer 52, and the antiferromagnetic coupling action of the ferromagnetic layer 53 / nonmagnetic conductor layer 54 / ferromagnetic layer 55. The direction of the magnetization M55 of the upper ferromagnetic layer 55 is fixed in the opposite direction to the magnetization M53 of the lower ferromagnetic layer 53.
The magnetization free layer (signal detection layer) 57 is composed of a ferromagnetic layer, and can change or reverse the direction of the magnetization M by the action of a magnetic field from the outside of the magnetoresistive effect element. Has been.
Then, for example, a signal based on information recorded on the recording medium can be detected by detecting a magnetic flux (magnetic field) generated corresponding to information recorded on the recording medium as an external magnetic field.
When manufacturing the magnetic memory element 50, the layers from the underlayer 51 to the cap layer 58 are continuously formed in a vacuum apparatus.
In this example, the magnetization fixed layer 61 is composed of a laminated film having a three-layer structure of a ferromagnetic layer 53 / nonmagnetic conductor layer 54 / ferromagnetic layer 55 in which upper and lower magnetic layers are antiferromagnetically coupled. However, there is no problem even if the magnetization fixed layer is composed of only one ferromagnetic layer.

  By the way, in the current surface direct type (CPP type) magnetic head, the magnetization state of the signal detection layer (magnetization free layer) becomes unstable due to the sense current, and a sense current of a certain level or more flows, so that the signal detection layer It is known that a phenomenon called spin injection magnetization reversal occurs that causes magnetization reversal (see, for example, Non-Patent Document 1).

Magnetization reversal by spin injection is to change the magnetization state by injecting spin-polarized electrons that have passed through a magnetic material into another magnetic material.
For example, two or more magnetic materials are perpendicular to the film surface of a giant magnetoresistive effect element (GMR element) or magnetic tunnel junction element (MTJ element) disposed via a conductor layer or a tunnel barrier layer. In CPP-type devices that pass current in the direction, the sense current is a phenomenon that changes the magnetization state of at least a part of the magnetic layer of these elements, and is observed as a phenomenon that the magnetization is reversed or that the magnetization vibrates at a high frequency. (See, for example, Non-Patent Document 2).

Physical Review Letters, 1998, 80, p. 4281 Nature, 2003, 425, p. 380

  When a magnetoresistive element is used in a magnetic reproducing head, the magnetization state of the signal detection layer reacts only to the leakage magnetic field from the recording medium and is less susceptible to other disturbances. It is necessary to increase the ratio (S / N ratio).

The change in the magnetization state of the signal detection layer due to the above-described spin injection phenomenon disturbs the signal detection layer and becomes noise, which causes a reduction in the S / N ratio.
For this reason, in a current surface direct type (CPP type) magnetic reproducing head, in order to realize a high S / N ratio, it is necessary to reduce the influence of the spin injection phenomenon.

  The present invention provides a magnetoresistive element capable of obtaining a good S / N ratio with little increase in noise even when a current is passed, and a magnetic head using the magnetoresistive element.

The magnetoresistive effect element of the present invention is provided between a magnetization fixed layer in which the magnetization direction is fixed, a magnetization free layer capable of changing the magnetization direction, and the magnetization fixed layer and the magnetization free layer. A laminated film having at least a nonmagnetic layer is formed, a current flows in a direction substantially perpendicular to the film surface of the laminated film, a conductor layer is provided in the vicinity of the magnetization free layer, and the conductor layer is formed of Pd. , Pt, Nd, Sm, Tb, Dy, and Ho.
The magnetic head of the present invention comprises the magnetoresistive effect element of the present invention, and magnetic shields are arranged above and below the magnetoresistive effect element via a nonmagnetic conductor layer.

According to the configuration of the magnetoresistive effect element of the present invention described above, a conductor layer is provided in the vicinity of the magnetization free layer, and the conductor layer includes at least one selected from Pd, Pt, Nd, Sm, Tb, Dy, and Ho. By using the main component, the conductor layer contains an element having a large number of conduction electrons, such as a heavy metal element or a rare earth element, so that spin scattering is large. As a result, it is possible to increase the damping constant of the magnetization free layer by exerting a large spin pumping effect from the conductor layer to the magnetization free layer, and to suppress the occurrence of the above-described spin injection magnetization reversal. Generation of noise due to magnetization reversal can be reduced.
According to the configuration of the magnetic head of the present invention, the magnetoresistive effect element of the present invention is provided, and magnetic shields are arranged above and below the magnetoresistive effect element via a nonmagnetic conductor layer. As a result, the magnetoresistive element is configured to reduce the generation of noise due to the spin injection magnetization reversal, so that the increase in noise can be reduced even when a sense current is passed.

According to the magnetoresistive effect element and the magnetic head of the present invention described above, it is possible to reduce the occurrence of noise due to spin injection magnetization reversal, and the increase in noise is small even when a sense current is passed. A ratio can be obtained.
Therefore, according to the present invention, a magnetic head having a good S / N ratio and generating less noise during reproduction can be realized.

  First, prior to description of specific embodiments of the present invention, an outline of the present invention will be described.

  As described above, the change in the magnetization state of the signal detection layer due to the spin injection phenomenon causes disturbance to the signal detection layer, resulting in noise and a reduction in the S / N ratio. Therefore, the current plane direct type (CPP type) In order to realize a high S / N ratio in the magnetic read head, it is necessary to reduce the influence of the spin injection phenomenon.

  In the spin injection phenomenon, it is theoretically derived that a theoretical formula that gives a threshold current for causing magnetization reversal is as shown in the following formula 1. Using this formula, if the damping constant is increased, It is theoretically calculated that the threshold current at which inversion occurs increases, and for this reason, when the same sense current is applied, the magnetization state is stabilized (JZ Sun, Phys. Rev. B, Vol. .62, p.570, 2000).

（ただし、α：記憶層のダンピング定数、Ｈ_ｋ：記憶層の一軸異方性磁界、Ｍ_ｓ：記憶層の飽和磁化、η：スピン注入係数）

(Where α is the damping constant of the storage layer, H _{k is} the uniaxial anisotropic magnetic field of the storage layer, M _{s is} the saturation magnetization of the storage layer, η is the spin injection coefficient)

  In addition, it has been reported that the conductor layer in contact with the magnetic layer increases the damping constant of the magnetic layer by affecting the damping constant, which is the material property of the magnetic layer, due to a phenomenon called spin pumping ( (For example, see Yaroslav et al., Phys. Rev. B, Vol. 66, P. 224403, 2002, Mizukami et al., J. Magn. Magn. Mater., Vol. 226-230, P. 1640, 2001).

  In the present invention, the material configuration of the magnetoresistive effect element is devised to set the damping constant to be increased by the spin pumping effect. And a magnetic head using the magnetoresistive effect element can be realized.

Therefore, in the magnetoresistive effect element of the present invention, in a magnetoresistive effect element (GMR element or TMR element or the like) having two or more magnetic bodies, a magnetization free layer (signal detection layer) whose magnetization direction is changed by an external magnetic field. ), A conductor layer having an effect of increasing the damping constant of the magnetization free layer (signal detection layer) is provided in the vicinity thereof. This conductor layer may be in direct contact with the magnetization free layer (signal detection layer), or may be disposed via another thin film.
The magnetic head according to the present invention includes the magnetoresistive effect element according to the present invention, and a magnetic shield is disposed above and below the magnetoresistive effect element via a nonmagnetic conductor layer.

As a material of the conductor layer having an effect of increasing the damping constant of the magnetization free layer (signal detection layer), a material having a large spin scattering is used so as to obtain a large spin pumping effect. For example, it is desirable to use heavy metals or rare earths with a large number of conduction electrons.
Specifically, for example, each element of Pd, Pt, Nd, Sm, Tb, Dy, and Ho, and an alloy / compound mainly composed of one or more selected from these elements can be given.

For example, there is shown an experimental result in which the damping constant of the NiFe layer increases when a Pt layer is disposed adjacent to the NiFe alloy layer (for example, Mizukami et al., J. Magn. Magn. Mater., Vol. .226-230, P.1640, 2001).
Therefore, when the magnetization free layer (signal detection layer) is a NiFe layer and a Pt layer is disposed adjacent to the NiFe layer, the spin injection magnetization reversal effect can be reduced according to the above-described equation 1 by the above-described spin pumping effect. .
For this reason, the magnetization state of the magnetization free layer (signal detection layer) when a current is passed can be stabilized, and therefore noise due to the spin injection phenomenon at the time of signal detection can be reduced.

However, generally, when a Pt layer is stacked on a NiFe layer and heat treatment is performed at about 300 ° C. or more, NiFe and Pt react at the interface, and the coercive force of NiFe increases.
In the manufacturing process of the magnetic head, heat treatment for orienting the magnetization direction of the magnetization fixed layer is generally performed, and the temperature is around 300.degree.
When a magnetoresistive element with the increased NiFe coercivity of the magnetization free layer (signal detection layer) is used in a magnetic head, the coercivity of the signal detection layer increases and the soft magnetic characteristics are impaired. Therefore, Barkhausen noise increases.
Not only Pt but also other materials of the above-described conductor layer, that is, when Pd, Nd, Sm, Tb, Dy, Ho, etc. are used, the coercive force of the signal detection layer is similarly increased and Barkhausen noise is generated. There is concern about the increase.

As a method for preventing this phenomenon, the second conductor material is made of a ferromagnetic material so that the magnetic properties of the ferromagnetic material constituting the magnetization free layer (signal detection layer) do not deteriorate even if interface diffusion occurs due to heat treatment. It is conceivable to arrange a conductor such as Pt through this second conductor material.
In this case, the second conductor material should not interfere with the spin pumping effect by the conductor such as Pt.

  Therefore, in the magnetoresistive effect element of the present invention, more preferably, the magnetization free layer (signal detection layer) is prevented from deteriorating the magnetic characteristics of the magnetization free layer (signal detection layer) due to the influence of the conductor layer in direct contact. ) And a conductor layer (first conductor layer), a different kind of conductor layer (second conductor layer) is inserted.

As a material for this different type of conductor layer (second conductor layer), a material having a long spin diffusion length and a small spin pumping effect is used. Furthermore, it is desirable that the material does not deteriorate the magnetic characteristics even when it comes into contact with the magnetization free layer (signal detection layer). That is, it is desirable that the electronic state is close to that of a light element or a transition metal element such as Fe, Co, or Ni that is a main component of a magnetic substance.
Specifically, for example, Ti / Cr / Cu / Ag / Au / Nb / Ta elements and alloys / compounds containing at least one selected from these elements as main components can be mentioned.

Furthermore, it is desirable that the thickness of this different type of conductor layer (second conductor layer) be 1 nm or more and 20 nm or less.
By setting the thickness within this range, the second conductor layer remains without interfering with the spin pumping effect by the first conductor layer, and even if interface diffusion occurs due to heat treatment during manufacturing, and the magnetization free layer ( The effect of suppressing the deterioration of the magnetic characteristics of the signal detection layer due to the diffusion of the magnetic material of the signal detection layer and the conductive material of the first conductor layer can be sufficiently obtained.

Subsequently, specific embodiments of the present invention will be described.
FIG. 1 shows a schematic configuration diagram (cross-sectional view) of an embodiment of a magnetoresistive element of the present invention.
The magnetoresistive effect element 10 includes a base layer 11, an antiferromagnetic layer 12, a ferromagnetic layer 13, a nonmagnetic conductor layer 14, a ferromagnetic layer 15, a tunnel barrier layer (tunnel insulating layer) 16, a substrate (not shown), A magnetization free layer (signal detection layer) 17, a conductor layer 18, and a cap layer 19 are laminated and formed.
Among these, the anti-ferromagnetic layer 12, and the laminated film of the three layers of the ferromagnetic layer 13, the nonmagnetic conductor layer 14, and the ferromagnetic layer 15 constitute the magnetization fixed layer 21 in which the magnetization direction of the magnetic material is fixed. Has been.

In the magnetization fixed layer 21, the direction of the magnetization M 13 of the lower ferromagnetic layer 13 is fixed by the antiferromagnetic layer 12, and the antiferromagnetic coupling action of the ferromagnetic layer 13 / nonmagnetic conductor layer 14 / ferromagnetic layer 15. The direction of the magnetization M15 of the upper ferromagnetic layer 15 is fixed in the opposite direction to the magnetization M13 of the lower ferromagnetic layer 13.
In the magnetoresistive element 10 of FIG. 1, the direction of the magnetization M13 of the lower ferromagnetic layer 13 is fixed to the right, and the direction of the magnetization M15 of the upper ferromagnetic layer 15 is fixed to the left.

The magnetization free layer (signal detection layer) 17 is composed of a ferromagnetic layer, and can change or reverse the direction of the magnetization M by the action of a magnetic field from the outside of the magnetoresistive effect element. Has been.
Then, for example, a signal based on information recorded on the recording medium can be detected by detecting a magnetic flux (magnetic field) generated corresponding to information recorded on the recording medium as an external magnetic field.

The magnetization fixed layer 21, the tunnel barrier layer (tunnel insulating layer) 16, and the magnetization free layer (signal detection layer) 17 constitute a tunnel magnetoresistive element (TMR element).
When a current is passed through the TMR element in a direction substantially perpendicular to the film surface of the laminated film, the direction of the magnetizations M13 and M15 of the magnetization fixed layer 21 and the direction of the magnetization M of the magnetization free layer (signal detection layer) 17 Thus, a tunnel magnetoresistive effect is produced in which the resistance value with respect to the current changes.
Using this tunnel magnetoresistance effect, a magnetic field can be detected, for example, a signal based on information recorded on a recording medium can be detected.
Specifically, when the direction of the magnetization M of the magnetization free layer (signal detection layer) 17 is parallel to the direction of the magnetization M15 of the upper ferromagnetic layer 15 of the magnetization fixed layer 21 (magnetization in FIG. 1). When M is leftward, the resistance value is low, and when it is antiparallel (when the magnetization M is rightward in FIG. 1), the resistance value is high.

For the ferromagnetic layers 13 and 15 constituting the magnetization fixed layer 21, for example, a material composed of one or more of Fe, Ni, and Co can be used.
The material of the magnetization free layer (signal detection layer) 17 needs to be excellent in soft magnetic characteristics in order to reduce Barkhausen noise. The body can be used. For example, a material composed of one or more of Fe, Ni, and Co (for example, NiFe alloy or CoFe alloy) can be used.

Further, these ferromagnetic layers 13, 15, and 17 can contain transition metal elements such as Nb and Zr and light elements such as B and C.
In general, the value of the saturation magnetization Ms of the ferromagnetic layers 13, 15, and 17 is suitably in the range of 200 emu / cc to 2000 emu / cc.

As the material of the antiferromagnetic layer 12, for example, a Mn compound such as PtMn, RhMn, RuMn, FeMn, and IrMn can be used.
As a material of the nonmagnetic conductor layer 14 constituting the magnetization fixed layer 21, a material such as Ru, Cu, Rh, Cr or the like that causes antiferromagnetic interlayer coupling between magnetic layers can be used.
As a material of the tunnel barrier layer (tunnel insulating layer) 16, Al ₂ O ₃ , MgO, HfO, SiO, SiO ₂ , SiN, or a mixture thereof can be used.
The material of the underlayer 11 and the cap layer 19 is not particularly limited, but generally, a metal such as Ta, Cr, Ti or the like is used.

In the magnetoresistive effect element 10 of the present exemplary embodiment, a conductor layer 18 is provided in contact with the magnetization free layer (signal detection layer) 17 in particular.
As the material of the conductor layer 18, for example, the above-described elements such as Pd, Pt, Nd, Sm, Tb, Dy, and Ho, and alloys / compounds mainly composed of one or more selected from these elements are used. .
As a result, a large spin pumping effect is applied from the conductor layer 18 to the magnetization free layer (signal detection layer) 17 to increase the damping constant of the magnetization free layer (signal detection layer) 17, and the above-described spin injection magnetization reversal phenomenon. Can be suppressed.

  The magnetoresistive effect element 10 of the present embodiment is formed by continuously forming the base layer 11 to the cap layer 19 in a vacuum apparatus, and then forming the pattern of the magnetoresistive effect element 10 by processing such as etching. Can be manufactured.

In addition, a magnetic head having the same configuration as the magnetic head shown in FIG. 4 can be configured using the magnetoresistive effect element 10 of the present embodiment.
That is, a lower magnetic shield / lower electrode is disposed under the magnetoresistive effect element 10 via a nonmagnetic conductor layer serving as a lower gap / lower connection electrode, and an upper gap is disposed on the magnetoresistive effect element 10. A magnetic head is configured by arranging an upper magnetic shield / upper electrode via a nonmagnetic conductor layer serving as an upper connection electrode.
Then, by passing a sense current between the upper electrode and the lower electrode, the sense current is caused to flow in a direction substantially perpendicular to the film surface of the laminated film of the magnetoresistive effect element 10, and the magnetization free layer of the magnetoresistive effect element 10. A change in the resistance value corresponding to the direction of the magnetization M of the (signal detection layer) 17 can be detected. Thereby, the magnetic field applied from the outside to the magnetic head can be detected.
Therefore, for example, a magnetic field based on information recorded on the storage medium can be detected, and the recorded information can be read or reproduced.

  According to the configuration of the magnetoresistive effect element 10 of the present embodiment described above, the conductor layer 18 is provided on and in contact with the magnetization free layer (signal detection layer) 17, and the conductor layer 18 is formed of Pd, Pt, Nd, Sm. , Tb, Dy, Ho, and an alloy / compound mainly composed of one or more selected from these elements, the conductor layer 18 is a conduction electron such as a heavy metal element or a rare earth element. Since a large number of elements are the main components, spin scattering is increased, and a large spin pumping effect is exerted from the conductor layer 18 to the magnetization free layer (signal detection layer) 17 to cause the magnetization free layer (signal detection layer). Increase the damping constant of 17. As a result, it is possible to suppress the occurrence of the above-described spin injection magnetization reversal, so that the generation of noise due to the spin injection magnetization reversal can be reduced.

In addition, since the magnetic head is provided with the magnetoresistive effect element 10 capable of reducing the generation of noise due to the spin injection magnetization reversal in this way, the increase in noise is small even when a sense current is passed. S / N ratio can be obtained.
Therefore, a magnetic head having a good S / N ratio and generating less noise during reproduction can be realized.

Next, FIG. 2 shows a schematic configuration diagram (cross-sectional view) of another embodiment of the magnetoresistance effect element of the present invention.
This magnetoresistive effect element 20 has a second conductor layer 22 between the magnetization free layer (signal detection layer) 17 and the conductor layer 18 in addition to the configuration of the magnetoresistive effect element 10 of the previous embodiment. Is provided.
The second conductor layer 22 includes a conductor layer (first conductor layer) 18 and a magnetization free layer (signal detection layer) 17 that are diffused at the interface by high-temperature heat treatment, so that the magnetization free layer (signal detection layer) 17 It is provided to suppress the phenomenon that the magnetic characteristics deteriorate.

  Examples of the material of the second conductor layer 22 include the above-described elements such as Ti, Cr, Cu, Ag, Au, Nb, Ta, and alloys / compounds mainly composed of one or more selected from these elements. Can be used.

More preferably, the thickness of the second conductor layer 22 is 1 nm or more and 20 nm or less.
As a result, the second conductor layer 22 remains without interfering with the spin pumping effect by the first conductor layer 18 and the occurrence of interface diffusion due to heat treatment during manufacturing, and the magnetization free layer (signal detection layer) 17 The effect of suppressing the deterioration of the magnetic characteristics of the magnetization free layer (signal detection layer) 17 due to the diffusion of the magnetic material and the conductor material of the first conductor layer 18 can be sufficiently obtained.

  Other configurations are the same as those of the magnetoresistive effect element 10 of the previous embodiment, and therefore, the same reference numerals are given and redundant description is omitted.

In addition, a magnetic head having the same configuration as the magnetic head shown in FIG. 4 can be configured using the magnetoresistive effect element 20 of the present embodiment.
That is, a lower magnetic shield / lower electrode is disposed under the magnetoresistive effect element 20 via a nonmagnetic conductor layer serving as a lower gap / lower connection electrode, and an upper gap is disposed on the magnetoresistive effect element 20. A magnetic head is configured by arranging an upper magnetic shield / upper electrode via a nonmagnetic conductor layer serving as an upper connection electrode.
Then, by passing a sense current between the upper electrode and the lower electrode, the sense current is caused to flow in a direction substantially perpendicular to the film surface of the laminated film of the magnetoresistive effect element 20, and the magnetization free layer of the magnetoresistive effect element 20. A change in the resistance value corresponding to the direction of the magnetization M of the (signal detection layer) 17 can be detected. Thereby, the magnetic field applied from the outside to the magnetic head can be detected.
Therefore, for example, a magnetic field based on information recorded on the storage medium can be detected, and the recorded information can be read or reproduced.

  According to the configuration of the magnetoresistive effect element 20 of the present embodiment described above, the conductor layer (first conductor layer) 18 is provided above the magnetization free layer (signal detection layer) 17, and the first conductor layer 18. Is constituted by using each element of Pd, Pt, Nd, Sm, Tb, Dy, Ho, and an alloy / compound mainly composed of one or more selected from these elements. As with the magnetoresistive effect element 10, the damping constant of the magnetization free layer (signal detection layer) 17 is increased by exerting a large spin pumping effect from the first conductor layer 18 to the magnetization free layer (signal detection layer) 17. Let As a result, it is possible to suppress the occurrence of the above-described spin injection magnetization reversal, so that the generation of noise due to the spin injection magnetization reversal can be reduced.

Further, since the magnetic head is configured by including the magnetoresistive effect element 20 capable of reducing the generation of noise due to the spin injection magnetization reversal in this way, the increase in noise is small even when a sense current is passed. S / N ratio can be obtained.
Therefore, a magnetic head having a good S / N ratio and generating less noise during reproduction can be realized.

Further, according to the configuration of the magnetoresistive effect element 20 of the present embodiment, the second conductor layer 22 is provided between the magnetization free layer (signal detection layer) 17 and the first conductor layer 18, and this first The second conductor layer 22 is composed of Ti, Cr, Cu, Ag, Au, Nb, Ta elements, or an alloy / compound mainly composed of one or more selected from these elements. Since the second conductor layer 22 is mainly composed of a light element or an element whose electronic state is close to that of a magnetic transition metal element (Fe, Co, Ni, etc.), the spin diffusion length of the second conductor layer 22 is long and the spin pumping effect is obtained. small.
Thereby, even if the magnetization free layer (signal detection layer) 17 and the second conductor layer 22 diffuse at the interface due to high-temperature heat treatment, the soft magnetic characteristics of the magnetization free layer (signal detection layer) 17 are unlikely to deteriorate. .
Therefore, even if high-temperature heat treatment is performed during manufacturing, deterioration of the soft magnetic characteristics of the magnetization free layer (signal detection layer) 17 is suppressed, and an increase in Barkhausen noise can be suppressed.

In each of the above-described embodiments, the magnetization fixed layer 21 is composed of the antiferromagnetic layer 12 and the ferromagnetic layer 13 / nonmagnetic conductor layer 14 / ferromagnetic layer in which the upper and lower ferromagnetic layers are antiferromagnetically coupled. However, the fixed magnetization layer may be formed of an antiferromagnetic layer and a single ferromagnetic layer.
In each of the above-described embodiments, the tunnel magnetoresistive element (TMR element) is configured with the tunnel barrier layer (tunnel insulating layer) 17 between the magnetization fixed layer 21 and the magnetization free layer (signal detection layer) 18. However, in the present invention, a giant magnetoresistive element (GMR element) may be configured using a nonmagnetic conductor layer between the magnetization fixed layer and the magnetization free layer (signal detection layer).

Further, the stacking order of the magnetization fixed layer and the magnetization free layer (signal detection layer) may be the reverse of the above-described embodiments.
In other words, the antiferromagnetic layer may be the uppermost layer, and the magnetization free layer (signal detection layer), nonmagnetic layer, and magnetization fixed layer may be stacked in that order from the bottom layer.

  Here, the magnetoresistive effect element of the present invention was actually manufactured and its characteristics were examined.

(Sample 1: Comparative example)
First, a thermal oxide film having a thickness of 2 μm was formed on a silicon substrate having a thickness of 0.575 mm, and the magnetoresistive effect element 50 having the configuration shown in FIG. 5 was formed thereon.
Specifically, in the magnetoresistive effect element 50 having the configuration shown in FIG. 5, the material and film thickness of each layer are as follows: the base film 51 is a Ta film with a film thickness of 3 nm, and the antiferromagnetic layer 52 is a PtMn film with a film thickness of 20 nm. The ferromagnetic layer 53 constituting the magnetization fixed layer 61 is a CoFe film having a thickness of 2 nm, the nonmagnetic conductor layer 54 constituting the magnetization fixed layer 61 is a Ru film having a thickness of 0.8 nm, and the magnetization fixed layer 61 is strong. The magnetic layer 55 is a CoFe film having a thickness of 4 nm, the tunnel barrier layer (tunnel insulating layer) 56 is an aluminum oxide film obtained by oxidizing an Al film having a thickness of 0.5 nm, and the magnetization free layer (signal detection layer) 57 is a film having a thickness of 2 nm. The CoFe film and the cap layer 58 were selected as Ta films with a thickness of 5 nm, and a Cu film with a thickness of 100 nm (not shown) was provided between the base film 51 and the antiferromagnetic layer 52 to form each layer.
That is, the laminated film of the magnetoresistive effect element 50 was produced with the material and film thickness of each layer as the following configuration (film configuration 1).
Membrane configuration 1:
Ta (3nm) / Cu (100nm) / PtMn (20nm) / CoFe (2nm) / Ru (0.8nm) / CoFe (4nm) / Al (0.5nm) -Ox / CoFe (2nm) / Ta (5nm)
In the above film configuration, the composition of the PtMn film was Pt50Mn50 (atomic%), and the composition of the CoFe film was Co90Fe10 (atomic%).
Each layer other than the tunnel barrier layer 56 made of an aluminum oxide film was formed using a DC magnetron sputtering method.
The tunnel barrier layer 56 made of an aluminum oxide (Al—Ox) film is formed by first depositing a metal Al film to a thickness of 0.5 nm by DC sputtering, then setting the oxygen / argon flow ratio to 1: 1, and the chamber gas pressure to The metal Al layer was oxidized by a natural oxidation method at 10 Torr. The oxidation time was 10 minutes.
Further, after each layer of the magnetoresistive effect element 50 was formed, a heat treatment at 10 kOe · 260 ° C. for 4 hours was performed in a heat treatment furnace in a magnetic field, and a regularized heat treatment was performed on the PtMn film of the antiferromagnetic layer 52.

Next, the magnetoresistive effect element 50 was produced using this laminated film.
First, after masking the portion to be the lower electrode by photolithography, the lower electrode was formed by performing selective etching with Ar plasma on the laminated film other than the lower electrode. At this time, the portion other than the lower electrode portion was etched to a depth of 5 nm of the substrate.
Thereafter, a mask of a pattern of the magnetoresistive effect element 50 was formed by an electron beam drawing apparatus, and selective etching was performed on the laminated film to form the magnetoresistive effect element 50. Except for the portion of the magnetoresistive effect element 50, etching was performed up to the Cu layer. At this time, the pattern of the magnetoresistive element 50 was a rectangular shape having a minor axis of 0.09 μm and a major axis of 0.18 μm.
In the magnetic reproducing head, since it is necessary to suppress the resistance value of the tunnel insulating layer of the TMR element in order to ensure high frequency response characteristics, the area / resistance value product (Ω · μm ² ) of the magnetoresistive effect element 50 is It was set to 10Ω · μm ² .
Next, the part other than the magnetoresistive effect element 50 was insulated by sputtering of Al ₂ O ₃ having a thickness of about 100 nm.
Then, the upper electrode was formed using photolithography.
In this way, a sample (comparative example) of the magnetoresistive effect element of Sample 1 was produced.

(Sample 2: Example 1)
First, a thermal oxide film having a thickness of 2 μm was formed on a silicon substrate having a thickness of 0.575 mm, and the magnetoresistive effect element 10 having the configuration shown in FIG. 1 was formed thereon.
Specifically, in the magnetoresistive effect element 10 having the configuration shown in FIG. 1, the material and film thickness of each layer are as follows: the under film 11 is a Ta film with a film thickness of 3 nm, and the antiferromagnetic layer 12 is a PtMn film with a film thickness of 20 nm. The ferromagnetic layer 13 constituting the magnetization fixed layer 21 is a CoFe film having a thickness of 2 nm, the nonmagnetic conductor layer 14 constituting the magnetization fixed layer 21 is a Ru film having a thickness of 0.8 nm, and the magnetization constituting the magnetization fixed layer 21 is strong. The magnetic layer 15 is a CoFe film having a thickness of 4 nm, the tunnel barrier layer (tunnel insulating layer) 16 is an aluminum oxide film obtained by oxidizing an Al film having a thickness of 0.5 nm, and the magnetization free layer (signal detection layer) 17 is a film having a thickness of 2 nm. The CoFe film, the conductor layer 18 is selected as a Pt film having a thickness of 20 nm, the cap layer 19 is selected as a Ta film having a thickness of 5 nm, and the Cu film having a thickness of 100 nm not shown between the base film 11 and the antiferromagnetic layer 12 is selected. Each layer was formed.
That is, the laminated film of the magnetoresistive effect element 10 was produced by setting the material and film thickness of each layer to the following configuration (film configuration 2).
Membrane configuration 2:
Ta (3nm) / Cu (100nm) / PtMn (20nm) / CoFe (2nm) / Ru (0.8nm) / CoFe (4nm) / Al (0.5nm) -Ox / CoFe (2nm) / Pt (20nm) / Ta (5nm)
In the above film configuration, the composition of the PtMn film was Pt50Mn50 (atomic%), and the composition of the CoFe film was Co90Fe10 (atomic%).
Each layer other than the tunnel barrier layer 16 made of an aluminum oxide film was formed using a DC magnetron sputtering method.
The tunnel barrier layer 16 made of an aluminum oxide (Al—Ox) film is formed by first depositing a metal Al film by 0.5 nm by DC sputtering, then setting the oxygen / argon flow ratio to 1: 1, and setting the chamber gas pressure to The metal Al layer was oxidized by a natural oxidation method at 10 Torr. The oxidation time was 10 minutes.
Further, after each layer of the magnetoresistive effect element 10 was formed, a heat treatment was performed at 10 kOe · 260 ° C. for 4 hours in a magnetic field heat treatment furnace, and a regularized heat treatment was performed on the PtMn film of the antiferromagnetic layer 12.

Next, the magnetoresistive effect element 10 was produced using this laminated film.
First, after masking the portion to be the lower electrode by photolithography, the lower electrode was formed by performing selective etching with Ar plasma on the laminated film other than the lower electrode. At this time, the portion other than the lower electrode portion was etched to a depth of 5 nm of the substrate.
Thereafter, a mask of the pattern of the magnetoresistive effect element 10 was formed by an electron beam drawing apparatus, and selective etching was performed on the laminated film to form the magnetoresistive effect element 10. Etching was performed up to just above the Cu layer except for the portion of the magnetoresistive element 10. At this time, the pattern of the magnetoresistive effect element 10 was a rectangular shape having a minor axis of 0.09 μm and a major axis of 0.18 μm. In the magnetic reproducing head, since it is necessary to suppress the resistance value of the tunnel insulating layer of the TMR element in order to ensure high frequency response characteristics, the area / resistance value product (Ω · μm ² ) of the magnetoresistive effect element 10 is It was set to 10Ω · μm ² .
Next, the part other than the magnetoresistive effect element 10 was insulated by sputtering of Al ₂ O ₃ having a thickness of about 100 nm.
Then, the upper electrode was formed using photolithography.
In this manner, a sample (Example 1) of the magnetoresistive effect element of Sample 2 was produced.

(Sample 3: Example 2)
The magnetoresistive effect element 20 shown in FIG. 2 is configured, the first conductor layer 18 is selected as a Pt film having a thickness of 20 nm, the second conductor layer 22 is selected as a Cu film having a thickness of 6 nm, and the other configurations are samples. 2 (Example 1), the laminated film of the magnetoresistive effect element 20 was produced.
That is, the laminated film of the magnetoresistive effect element 20 was produced by setting the material and film thickness of each layer as the following configuration (film configuration 3).
Membrane configuration 3:
Ta (3nm) / Cu (100nm) / PtMn (20nm) / CoFe (2nm) / Ru (0.8nm) / CoFe (4nm) / Al (0.5nm) -Ox / CoFe (2nm) / Cu (6nm) / Pt (20nm) / Ta (5nm)
Thereafter, a sample (Example 2) of the magnetoresistive effect element of Sample 3 was produced in the same manner as Sample 2 (Example 1).

(Measurement of noise)
The noise of each sample of sample 1 to sample 3 was measured.
Specifically, a current of 0.5 mA is passed as a sense current at the time of signal detection, and in this state, when an external magnetic field is not applied and when an external pseudo signal magnetic field is applied by a stationary evaluation apparatus, Noise contained in the output was measured using a spectrum analyzer.
The noise signal was determined by comparing the two measured spectra (without magnetic field and with magnetic field).
Then, the relative value of the noise signal was obtained by setting the noise signal of the sample of Sample 1 (Comparative Example) to 1 (reference value).
The results are summarized in Table 1.

  From the results in Table 1, it is possible to suppress the occurrence of noise by adopting the configuration of the present invention in which the conductor layer is provided for the magnetization free layer (signal detection layer) as in Sample 2 and Sample 3. I know that there is.

Next, samples of the magnetoresistive effect element (sample 1 to sample 3) subjected to higher temperature heat treatment at 340 ° C. for 1 hour in the same film configuration were prepared, and noise was similarly measured.
The results are shown in Table 2.

From the results of Table 2, when the heat treatment temperature becomes high, the noise signal increases due to the increase in Barkhausen noise in Sample 2 (Example 1), but Sample 3 (2) provided with the second conductor layer 22 ( In the case of Example 2), it can be seen that there is no increase in noise and that good characteristics are maintained.
That is, it can be seen that the provision of the second conductor layer 22 suppresses the deterioration of the magnetic characteristics of the magnetization free layer (signal detection layer) due to the high-temperature heat treatment.

  The present invention is not limited to the above-described embodiments and examples, and various other configurations can be employed without departing from the gist of the present invention.

It is a schematic block diagram (sectional drawing) of the magnetoresistive effect element of one embodiment of this invention. It is a schematic block diagram (sectional drawing) of the magnetoresistive effect element of other embodiment of this invention. It is the figure which showed typically the magnetic head of a CIP type | mold detection system. It is the figure which showed typically the magnetic head of a CPP type | mold detection system. It is sectional drawing which showed schematic structure of the magnetoresistive effect element which consists of a conventional TMR element.

Explanation of symbols

10, 20 Magnetoresistive effect element, 11 Underlayer, 12 Antiferromagnetic layer, 13, 15 Ferromagnetic layer, 14 Nonmagnetic conductor layer, 16 Tunnel barrier layer (tunnel insulating layer), 17 Magnetization free layer (signal detection layer) , 18 Conductor layer (first conductor layer), 19 Cap layer, 21 Magnetization fixed layer, 22 Second conductor layer

Claims (4)

It has at least a magnetization fixed layer in which the magnetization direction is fixed, a magnetization free layer capable of changing the magnetization direction, and a nonmagnetic layer provided between the magnetization fixed layer and the magnetization free layer A laminated film is formed,
A magnetoresistive effect element in which a current flows in a direction substantially perpendicular to the film surface of the laminated film,
A conductor layer is provided in the vicinity of the magnetization free layer,
The magnetoresistive effect element characterized in that the conductor layer contains as a main component at least one selected from Pd, Pt, Nd, Sm, Tb, Dy, and Ho.   A second conductor layer mainly comprising at least one selected from Ti, Cr, Cu, Ag, Au, Nb, and Ta is provided between the magnetization free layer and the conductor layer. The magnetoresistive effect element according to claim 1.   The magnetoresistive element according to claim 2, wherein the thickness of the second conductor layer is 1 nm or more and 20 nm or less. It has at least a magnetization fixed layer in which the magnetization direction is fixed, a magnetization free layer capable of changing the magnetization direction, and a nonmagnetic layer provided between the magnetization fixed layer and the magnetization free layer A laminated film is formed, and includes a magnetoresistive effect element in which a current flows in a direction substantially perpendicular to the film surface of the laminated film,
With respect to the magnetoresistive effect element, a magnetic head in which magnetic shields are arranged above and below via a nonmagnetic conductor layer,
The magnetoresistive effect element is provided with a conductor layer in the vicinity of the magnetization free layer, and the conductor layer is mainly composed of one or more selected from Pd, Pt, Nd, Sm, Tb, Dy, and Ho. Characteristic magnetic head.

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