JP2003031869A - Magnetoresistive effect element, magnetic head, and magnetic memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, when a ferromagnetic material of Ni-Fe, etc., is used for the foundation layer of a magnetoresistive effect element using an antiferromagnetic material, the directions of magnetization of a free magnetic layer and a fixed magnetic layer are changed by the influence from the foundation layer and the element becomes difficult to obtain outputs and thermally stable characteristics. SOLUTION: A magnetoresistive effect element which is improved in output characteristic and shows thermally stable characteristics is obtained by reducing the influence of a magnetic material constituting the foundation layer of an antiferromagnetic layer constituting the element on the directions of magnetization of the free and fixed magnetic layers by constituting the foundation layer in a three-layer structure of a first ferromagnetic foundation layer, a first nonmagnetic foundation layer, and a second ferromagnetic foundation layer. In addition, a high-density magnetic head and a large-capacity high-speed magnetic memory (MRAM) can be realized by using the magnetoresistive effect element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density magnetic recording / reproducing head (magnetic disk, magneto-optical disk, magnetic tape, etc.), a magnetic sensor used in automobiles, and a magnetic random access memory (MRAM). Is.

[0002]

2. Description of the Related Art In recent years, Fe / Cr artificial lattice multilayer films (Physical
Since the discovery of the giant magnetoresistance effect (GMR: Giant Magnet Resistance) in Review Letters Vol. 61, p2472 (1998)), we have used the magnetoresistance effect (MR) based on the conduction phenomenon depending on the spin of electrons. , A reproducing magnetic head that reads out the magnetization of a medium recorded at high density such as a hard disk device or a non-volatile magnetic random access memory (MRAM:
Application development to Magnetic Random AccessMemory) is active. GMR depends on the scattering depending on the electron spin when the magnetization directions of the magnetic layers adjacent to each other through the nonmagnetic layer in the multilayer film such as [magnetic layer / nonmagnetic layer / magnetic layer] are parallel or antiparallel. This is a phenomenon that occurs. When the magnetizations are parallel, the magnetic scattering probability is small and the resistance value is small. When the magnetizations are antiparallel, the magnetic scattering probability is high and the resistance value is large. GMR uses a conductive non-magnetic layer such as Cu for the non-magnetic layer, but uses an insulating layer such as Al ₂ O _{3 for the} non-magnetic layer and arranges electrodes on the top and bottom of the device film to depend on spin. The magnetoresistive effect obtained by the tunneling effect is called Tunneling Magnet Resistance (TMR), and its basic principle is Julliere (Physics Letters, vol1. 54A (197).
5). No.3, p225). TMR was a phenomenon at a low temperature at the beginning of Julliere's report, and the magnetoresistance change rate (MR ratio) was also small, so it was not paid much attention. In recent years, Miyazaki (Journal Magnetism and Magnetic Materials 139 p
231 (1995)) has been actively studied since the discovery of the TMR phenomenon with an MR ratio of nearly 20% at room temperature.

A magnetoresistive effect element (MR element) called a spin valve has been proposed in order to use the GMR or TMR as a device which operates in a minute magnetic field (Physical Review).
B Vol.43, p1297 (1991)). A spin valve is a stack of two ferromagnetic layers with a non-magnetic layer interposed between them. The magnetization direction of one magnetic layer (fixed magnetic layer) is antiferromagnetic such as Fe-Mn, Ir-Mn, or Pt-Mn. The magnetization direction of the fixed magnetic layer is fixed by the exchange bias magnetic field by the layer, and the magnetization direction of the other magnetic layer (free magnetic layer) is freely moved with respect to the external magnetic field. To change the electric resistance.

Various materials have been studied for the antiferromagnetic layer used in the spin valve film, and details have been reported by Jinbo (Journal of Applied Magnetics, Vol.22, No.1, p12 (1998)). There is. Especially when trying to put GMR and TMR into practical use for magnetic heads and nonvolatile magnetic memories, Mn antiferromagnetic materials are superior. As an Mn antiferromagnet, a disordered system (Ir-Mn, Rh-Mn, Ru-Mn, Rh) of the fcc (face centered cubic) structure of a γ-type Mn alloy that exchange-couples with a ferromagnetic film in the As-depo state -Ru-Mn, etc.) Antiferromagnetic material and C that causes exchange coupling by high temperature heat treatment at 200 ℃ or higher
uAu-I type fct (face centered square) ordered system (Ni-Mn, Pt-M
n, Pd-Pt-Mn, etc.) antiferromagnets. Figure 2 shows the antiferromagnetic layer
In order to make the antiferromagnetic layer exchange-couple with the pinned magnetic layer in the spin valve structure in which the antiferromagnetic layer, the pinned magnetic layer, the nonmagnetic layer, and the free magnetic layer are stacked in this order from the substrate side as shown in FIG. For this, an underlayer for controlling the structure of the antiferromagnetic layer plays an important role. When a disordered antiferromagnetic material is used for the antiferromagnetic layer of the spin valve structure as shown in FIG. 2, it is used as an underlayer for structure control in order to obtain the fcc-γ phase.
Ta, Nb, Ti, Hf, Zr, etc. are used, and N with fcc structure
i-Fe buffer layer, ie substrate / Ta underlayer / Ni-Fe
Good antiferromagnetic properties are exhibited by the film structure of the underlayer / irregular antiferromagnetic layer / fixed magnetic layer / nonmagnetic layer / free magnetic layer. In the case of an ordered antiferromagnetic layer, Ta, Nb, Ti, Hf, Zr, etc. are mainly used as the underlayer, and these underlayers show antiferromagnetic properties, but similar to the disordered antiferromagnetic material. In addition, it has been reported that good antiferromagnetic properties are exhibited even when using a structure such as Ta underlayer / Ni-Fe underlayer (Applied Physics Letters 65 (9), p1183, (1994), I
EEE Transaction Magnetism 33, p3592, (1997)).

[0005]

However, when Ni-Fe is used as the underlayer of the antiferromagnetic layer constituting the spin valve, not only the leakage magnetic field from the pinned magnetic layer but also the leakage magnetic field as shown in FIG. Due to the leakage magnetic field from the Ni-Fe underlayer, the originally determined magnetization direction of the free magnetic layer 1 (the direction indicated by the dotted line in the figure) is rotated, and the magnetizations of the pinned magnetic layer 1 and the free magnetic layer 1 are changed. There is a problem that the desired magnetic arrangement is not obtained and the magnetic field response of the output is deteriorated. In particular, as the density of magnetic heads and non-volatile magnetic memories has increased, the miniaturization of MR elements has progressed, and the above-mentioned problems become a problem.

In the case of a GMR element, there is a problem that a large MR ratio cannot be obtained due to a shunt current loss that does not contribute to the magnetoresistive effect because the Ni-Fe underlayer has a low resistivity.

As shown in FIG. 3B, the leakage magnetic field (dotted line arrow) from the Ni-Fe underlayer affects the magnetization direction of the pinned magnetic layer 1, but the magnetization of the pinned magnetic layer 1 is opposite. Since it is fixed by exchange coupling with the ferromagnetic layer 1, it has little effect in changing the magnetization direction in the operating range at room temperature. However, the strength of exchange coupling of the antiferromagnetic layer 1 to the pinned magnetic layer 1 becomes weaker as the temperature rises. That is, at a high temperature, the leakage magnetic field from the Ni—Fe underlayer further weakens the magnetization direction of the pinned magnetic layer 1 whose exchange coupling is weakened, which causes a problem of output reduction. In particular, the antiferromagnetic layer 1 is required to have a small film thickness in order to cope with the narrowing of the gap accompanying the increase in recording density. In this case, the influence is particularly large. Moreover, when manufacturing a magnetic head using an MR element, a heat treatment process at 250 ° C to 300 ° C is performed, so heat resistance and corrosion resistance that can withstand the manufacturing process are required. further
If it is installed in the HDD, the operating environment temperature (for example, 1
Thermal stability is required for stable characteristic operation for a long time at about 50 ° C. In addition, a TMR element is created on CMOS and M
Although research on application as a RAM device is progressing, CMOS
In the process, it is unavoidable to perform a very high temperature heat treatment process at 400 ° C to 450 ° C. Therefore, in consideration of application of the spin valve to a magnetic head or MRAM, there is a problem of output characteristic deterioration due to the high temperature heat treatment, and it is essential to solve these problems.

[0008]

A magnetoresistive element according to the present invention comprises a substrate, on which at least an antiferromagnetic layer is formed in order from the substrate side.
The pinned magnetic layer, the first non-magnetic layer, and the free magnetic layer are laminated, and the pinned magnetic layer is magnetically coupled to the antiferromagnetic layer so that the magnetization can be easily rotated by an external magnetic field. No
The free magnetic layer is a magnetoresistive effect element whose magnetization is easily rotated by an external magnetic field and whose resistance value is different due to a difference in relative angle between magnetization directions of the fixed layer and the free magnetic layer. An underlayer including at least one underlayer nonmagnetic layer and at least two underlayer ferromagnetic layers is provided between the substrate and the first underlayer, and the underlayer includes a first underlayer nonmagnetic layer and a first underlayer nonmagnetic layer. The above object is achieved by a magnetoresistive effect element including at least one multi-layered film composed of a second underlying ferromagnetic layer, wherein the underlying layer and the antiferromagnetic layer are in contact with each other.

The first underlayer ferromagnetic layer may be in contact with the antiferromagnetic layer.

The first and second underlayer ferromagnetic layers stacked via the first underlayer nonmagnetic layer are antiferromagnetically exchange-coupled, and the first underlayer nonmagnetic layer is Ru, Ir, Rh, Re,
It is desirable to contain either Cu or Cr.

Further, when the saturation magnetizations of the first and second underlayer magnetic layers are M ₁ and M ₂ and the film thicknesses are t ₁ and t ₂ , respectively, the products M ₁ × t ₁ and M ₂ × t, respectively. It is desirable that ₂ are approximately the same.

The underlayer magnetic layer forming the underlayer preferably contains Ni, Ni—Fe alloy or Co—Fe alloy.

Further, the underlayer magnetic layer forming the underlayer may be made of the same material as the pinned magnetic layer or the free magnetic layer.

The underlayer has a structure in which a second underlayer nonmagnetic layer, a second underlayer magnetic layer, a first underlayer nonmagnetic layer, and a first underlayer magnetic layer are laminated in this order from the substrate side. The magnetic layer may be made of at least one selected from Ta, Hf, Zr, Ti, W, Nb, Pt, Cr, Au and Cu.

The antiferromagnetic layer is an A-Mn alloy (where A is P
It is preferable that at least one element selected from t, Ni, Pd, Cr, Rh, Re, Ir, and Ru) is included.

In particular, the pinned magnetic layer constituting the spin valve further comprises a non-magnetic layer for exchange coupling, and a first magnetic layer and a second magnetic layer which are antiferromagnetically exchange-coupled via the non-magnetic layer for exchange coupling.
The exchange coupling non-magnetic layer includes a magnetic layer, Ru, Ir, Rh,
It may contain any one of Re, Cu and Cr. Further, the non-magnetic material may be made of at least one of Cu, Ag, Au, Cr or Ru. Further, the non-magnetic layer may be made of Al oxide, nitride or oxynitride.

Electrode layers are arranged above and below the film surface of the magnetoresistive element constituting the magnetoresistive element of the present invention, as shown in FIG. The above-mentioned object is achieved by the feature that the film is made to flow perpendicularly to the film surface.

By providing the magnetoresistive effect element of the present invention with a shield portion as shown in FIG.
A magnetoresistive head having a reproducing head section capable of detecting a signal magnetic field having high output and excellent thermal stability can be realized, and the above object can be achieved.

As shown in FIG. 12, an example of the magnetoresistive element of the present invention is a yaw constructed by using a soft magnetic material provided to introduce a magnetic field to be detected into the magnetoresistive element.
The provision of the magnetic head enables a magnetoresistive head having a reproducing head section for detecting a signal magnetic field, thereby achieving the above object.

By using the magnetic head having the shield type or yoke type reproducing head of the present invention as shown in FIGS. 11 and 12, it is possible to provide a high density magnetic recording device, and the above object is achieved. To be done.

If the magnetoresistive effect element portion of the present invention further comprises a sense line (bit line) portion for reading information and a word line portion for recording information, as shown in FIG. It becomes a magnetic memory element, and by arranging these magnetic memory elements in a matrix and providing a drive circuit, a magnetic random access memory (MRAM) element exhibiting high density and excellent thermal stability characteristics becomes possible. To be achieved.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetoresistive effect element of the present invention will be described below.
A magnetoresistive head and a magnetoresistive memory element will be described with reference to the drawings.

FIG. 1 is an example of a sectional view showing the structure of the magnetoresistive effect element of the present invention. In FIG. 1, the pinned magnetic layer 1 and the free magnetic layer 1 are magnetically separated by the non-magnetic layer 1,
The magnetization of the free magnetic layer 1 is easily rotated by an externally applied magnetic field, and the magnetization of the fixed magnetic layer 1 is not easily rotated by an externally applied magnetic field due to exchange coupling from the antiferromagnetic layer 1. In FIG. 1, the underlayer 1 is formed on a substrate (not shown), and the antiferromagnetic layer 1 is laminated on the underlayer 1.

In FIG. 1, the underlayer 1 has a structure in which a first underlayer ferromagnetic layer and a second underlayer ferromagnetic layer are laminated with a first underlayer nonmagnetic layer interposed therebetween. The present invention is characterized in that the first underlayer ferromagnetic layer and the second underlayer ferromagnetic layer forming the underlayer 1 are antiferromagnetically exchange-coupled via the first underlayer nonmagnetic layer.

Ru, Ir, Rh, R are used as the first underlayer nonmagnetic layer.
It is desirable to use e, Cu and Cr. These metals have a large effect of antiferromagnetically exchange-coupling the first underlayer ferromagnetic layer and the second underlayer ferromagnetic layer by using an appropriate film thickness. The magnetization directions of the first and second underlying ferromagnetic layers that are antiferromagnetically exchange-coupled are antiparallel.

FIG. 2 shows a conventional structure in which a Ta underlayer / Ni-Fe underlayer is used as the underlayer.

FIG. 3A is a perspective view of the MR element of the present invention shown in FIG. 1, and FIG. 3B is a perspective view of the MR element having the configuration shown in FIG. FIGS. 3A and 3B show the state of the leakage magnetic field when a ferromagnetic layer is used as the underlayer.
In the case of using a spin valve as the magnetic head, the magnetization directions of the pinned magnetic layer 1 and the free magnetic layer 1 are 90
Place it so that it becomes °. Particularly in this case, the usefulness of the present invention will be described below with reference to FIG. In the case where the Ta underlayer / Ni-Fe underlayer is used as the underlayer as in 3 (b), the leakage magnetic field from Ni-Fe reaches the free magnetic layer, so that the free magnetic layer 1 should originally be oriented. The magnetization is directed in a direction deviating from the magnetization direction (dotted line direction) that does not occur, which deteriorates the external magnetic field response. However, in the MR element of the present invention as shown in FIG. 3A, the magnetization directions of the first and second underlayer ferromagnetic layers are antiparallel, and therefore, as shown by arrows in the figure, respectively. The leakage magnetic field from the underlayer reaching the free magnetic layer 1 due to the mutual cancellation of the leakage magnetic fields can be reduced as compared with FIG. 3B, and the magnetic field response of the free magnetic layer 1 is improved. In particular, the saturation magnetizations of the first and second underlayer ferromagnetic layers are M ₁ and M ₂ , respectively, and the film thickness is t
_{If 1} and t ₂ , their respective products are M ₁ × t ₁ ≦ M ₂ × t ₂
When the relationship of is satisfied, it is possible to reduce the influence of the leakage magnetic field from the underlayer on the free magnetic layer 1. Especially M ₁
When xt ₁ and M ₂ xt ₂ are substantially the same, the respective leakage magnetic fields cancel each other out, which is particularly excellent.

In FIG. 3B, the leakage magnetic field from the Ni-Fe underlayer also affects the magnetization direction of the pinned magnetic layer 1, but the magnetization of the pinned magnetic layer 1 is exchange-coupled with the antiferromagnetic layer 1. Since it is fixed, there is little effect in changing the magnetization direction in the operating range at room temperature. However, the strength of exchange coupling of the antiferromagnetic layer 1 to the pinned magnetic layer 1 becomes weaker as the temperature rises. That is, at a high temperature, the leakage magnetic field from the Ni—Fe underlayer further weakens the magnetization direction of the pinned magnetic layer 1 whose exchange coupling is weakened, which causes a problem of output reduction. In particular, the antiferromagnetic layer 1 is required to have a small thickness in order to cope with the narrowing of the gap accompanying the increase in recording density, but in this case, the influence becomes particularly large.

Therefore, as shown in FIG. 3A, the MR of the present invention is used.
Since the leakage magnetic field from the underlayer can be reduced by adopting the element structure, the output decreases due to the change in the magnetization direction of the pinned magnetic layer 1 due to the high temperature manufacturing process and the operating temperature rise of the element. Can be prevented. Further, it is possible to prevent a decrease in output due to a leakage magnetic field from the underlayer due to the thinning of the antiferromagnetic layer 1. Therefore, the heat resistance of the MR characteristics of the device can be improved.

Further, in the structure of the underlayer of the present invention, since the magnetization directions of the first and second underlayer ferromagnetic layers are antiparallel, the resistance is larger than the parallel magnetization arrangement (the principle of appearance of GMR). . Therefore, the resistance becomes larger than that in the case of the Ni-Fe underlayer of FIG. 2 (or FIG. 3B), so that the current shunt (shunt current) that does not contribute to GMR is reduced, and a larger magnetoresistance change rate is obtained. It becomes possible to obtain.

As shown in FIG. 4, a second underlayer nonmagnetic layer may be provided on the substrate side of the second underlayer ferromagnetic layer of the MR element of the present invention shown in FIG. In this case, the second underlayer non-magnetic layer is Ta, Hf,
It is preferable to be composed of at least one selected from Zr, Ti, W, Nb, Pt, Cr, Au and Cu. These play a role as an adhesion control layer with the substrate and an orientation control layer of the second underlying ferromagnetic layer.

Further, as shown in FIG. 5, in the structure of the underlayer shown in FIG. 1, a third underlayer ferromagnetic layer may be further provided via a second underlayer nonmagnetic layer. In this case, the first, second and third
The magnetization directions of the underlying ferromagnetic layers are antiparallel to each other, and it is possible to reduce the leakage magnetic field from the underlying layer. Therefore, similarly, the fourth, fifth, ... Underlayer ferromagnetic layers are laminated via the fourth, fifth, ... Underlayer nonmagnetic layers, and each of the underlayer ferromagnetic layers is overlaid via the adjacent underlayer nonmagnetic layer. An antiferromagnetically exchange-coupled structure may be adopted, which is antiparallel.

Forming a base layer in the MR element of the present invention
The underlying ferromagnetic layer is Ni-Co-Fe with fcc (face centered cubic) structure
Alloy film is suitable. Specifically, the atomic composition of the Ni-Co-Fe film
The ratio is Ni_xCo_yFe_z(0.6 ≦ x ≦ 0.9, 0 ≦ y ≦ 0.4, 0 ≦
z ≦ 0.3) or Ni_{x '}Co_{y '}Fe _{z '}(0≤x'≤0.4, 0.2≤y '
≤0.95, 0≤z'≤0.5) is desirable. Among these, especially Ni_xF
e_1-x(0.6 ≦ x ≦ 1) or Co_yFe_1-y(0.7 ≦ y ≦ 0.95)
Is especially desirable. Each underlying ferromagnetic layer is a stack of these alloy films
It may be a film.

Since the underlayer constituting the MR element of the present invention plays a role as a structure control layer of the antiferromagnetic layer, its thickness is the total thickness of the underlayer ferromagnetic layer constituting the underlayer (see FIG. 1). The sum of the film thicknesses of the first and second underlayer ferromagnetic layers) must be at least 1 nm or more. If the thickness is less than this value, the semi-elevated magnetic layer formed on the underlayer is improved in crystal orientation and excellent antiferromagnetic properties, that is, a large exchange coupling magnetic field between the antiferromagnetic layer and the pinned magnetic layer is obtained. The problem arises that you will not be able to obtain it. More desirably, the total thickness of the underlying ferromagnetic layer is
2nm or more is good.

As the antiferromagnetic layer 1, an A-Mn alloy (however, A
Is preferably at least one element selected from Pt, Ni, Pd, Cr, Rh, Re, Ir and Ru). In the example, Pt-Mn, P
Examples include d-Mn, Pd-Pt-Mn, Ni-Mn, Ir-Mn, Cr-Pt-Mn, Ru-Rh-Mn.

Further, as shown in FIG. 6, the pinned magnetic layer 1 shown in FIG. 1 has two pinned magnetic layers 10 in which the pinned magnetic layer 1 is antiferromagnetically exchange-coupled via the pinned nonmagnetic layer 10. It may be configured by 11 and 11. With such a structure, the magnetization rotation is less likely to occur with respect to the external magnetic field, that is, the exchange coupling magnetic field of the pinned magnetic layer 1 is increased.
It is possible to obtain a magnetoresistive effect element that is thermally stable. In this case, Ru, Ir, Rh, Re, Cu, as the fixed nonmagnetic layer 10 are formed in the same manner as the underlayer nonmagnetic layer constituting the underlayer of the present invention.
It is desirable to use Cr.

Co, Fe, Co--Fe, N are used as magnetic materials for the free magnetic layer 1, the pinned magnetic layer 1, and the pinned magnetic layers 10 and 11.
It is desirable to use an alloy film of i-Fe, Ni-Co-Fe, or the like, or a laminated film thereof. In particular, it is desirable to use a material having excellent soft magnetic characteristics for the free magnetic layer 1. This is because Ni _x Co _y Fe _z (0.6 ≦ x ≦
0.9,0 ≦ y ≦ 0.4,0 ≦ z ≦ 0.3) or _{Ni x 'Co y' Fe z} '(0
≦ x '≦ 0.4, 0.2 ≦ y' ≦ 0.95, 0 ≦ z '≦ 0.5) or Ni _x F
e _1-x (0.6 ≦ x ≦ 1) or Co _y Fe _1-y (0.7 ≦ y ≦ 0.95)
Alloys are preferred. By using the same material as the underlying ferromagnetic layer for the free magnetic layer 1 or the fixed magnetic layer 1 in this way, the number of targets during thin film formation is not increased, and therefore the additional effects of simplifying the manufacturing process and reducing costs are achieved. Can be expected.

When the nonmagnetic layer 1 for magnetically separating the free magnetic layer 1 and the pinned magnetic layer 1 is a conductive material,
It is desirable to use Cu, Au, Ag, Ru, Cr, and alloys thereof. In the case of a non-magnetic insulator (that is, a tunnel insulating layer), any insulator or semiconductor may be used, but in particular, IIa to VI containing Mg, Ti, Zr, Hf, V, Nb, Ta, Cr.
It is a compound of an element selected from lanthanoids containing a, La and Ce and IIb to IVb containing Zn, B, Al, Ga and Si and at least an element selected from F, O, C, N and B. It is preferable. Oxides, nitrides, or oxynitrides of Al are particularly preferable because they have excellent insulating properties, can be thinned, and have excellent reproducibility as compared with other materials. When a conductive film such as Cu is used for the non-magnetic layer 1, it is a GMR element and, for example, electrodes are provided on the left and right of the element of FIG. 1 to form an MR element. When an Al oxide film or the like is used for the non-magnetic layer 1, it becomes a TMR element and, for example, electrodes are provided above and below the film of FIG. 1 to form an MR element as shown in FIG. 7 (details will be described later).

To form the MR element of the present invention, pulse laser deposition (PLD), ion beam deposition (IB)
D), cluster-ion beam or RF, DC, ECR, helicon, ICP or opposite target sputtering method, MBE, ion plating method or other PVD method, or other CVD, plating or sol-gel method can do.

In particular, when the non-magnetic layer is a tunnel layer and is an insulator, for example, Mg, Ti, Zr, Hf, V, Nb, Ta, Cr.
IIa to IVa including, La, including Ce, lanthanoid, Zn,
A thin film precursor of an element or alloy or compound selected from IIb to IVb including B, Al, Ga and Si is prepared, and this is prepared.
F, O, C, N, B element, molecule or ion,
By reacting in an appropriate atmosphere containing radicals and the like at a temperature and for a time, almost complete fluorination, oxidation, carbonization, nitriding, and boride treatment can be performed. Further, as a thin film precursor, F, O,
A non-stoichiometric compound containing C, N, and B in a stoichiometric ratio or less is prepared, and an appropriate atmosphere, temperature, and time containing any element, molecule, ion, or radical of F, O, C, N, or B are prepared. , May be made reactive. For example, when Al ₂ O ₃ is formed as a tunnel insulating layer by using a sputtering method, Al or AlO _X (X ≦ 1.5) is formed into a film in an Ar atmosphere or an Ar + O ₂ atmosphere. O ₂ or O ₂
+ It can be realized by repeating the reaction in an inert gas. For plasma and radical production, ECR discharge,
It can be generated by conventional means such as glow discharge, RF discharge, helicon or inductively coupled plasma (ICP).

Further, in order to prepare a magnetic device in which the MR element of the present invention causes a current to flow in the direction perpendicular to the film surface, a physical process such as ion milling, RIE, FIB or the like used in a semiconductor process, a GMR head manufacturing process or the like is performed. It is possible to fabricate an element as shown in FIG. 15 by performing fine processing by combining a chemical etching method and a photolithography technique using a stepper, an EB method or the like for forming a fine pattern. A current is passed through the magnetoresistive effect element portion 505 sandwiched between the upper electrode 502 and the lower electrode 503 to read the voltage.
The interlayer insulating film 501 has a function of preventing an electrical short circuit between the upper electrode and the lower electrode. With the element configuration shown in FIG. 15, it becomes possible to pass a current in the direction perpendicular to the film surface of the magnetoresistive effect element section 505 and read the output. It is also effective to use CMP or cluster-ion beam etching for flattening the surface of electrodes and the like. A low resistance metal such as Pt, Au, Cu, Ru or Al may be used as the electrode material. As the interlayer insulating film 501, a film having excellent insulating characteristics such as Al ₂ O ₃ or SiO ₂ may be used.

A magnetoresistive head can be constructed by using the magnetoresistive element of the present invention as described above. FIG. 7 shows an example of the configuration of the head. Figure 7 arrow A
8 is a view as seen from the direction of FIG. 8 and a cross section taken along the plane indicated by the dotted line B is shown in FIG. Hereinafter, a description will be given mainly with reference to FIG.

In FIG. 8, the MR element portion 109 is constructed so as to be sandwiched between the upper and lower shield gaps 14 and 11. As the shield gap material, Al ₂ O ₃ , AlN,
An insulating film such as SiO ₂ is used. Shield gap 11, 1
On the outer side of 4, there are upper and lower shields 10 and 15, which are made of a soft magnetic film of Ni-Fe, Fe-Al-Si, Co-Nb-Zr alloy or the like. A bias magnetic field is applied by the hard bias portion 12 such as a Co-Pt alloy for controlling the magnetic domains of the free magnetic layer 1 of the MR element.

Although the case where the hard film is used as the bias applying method has been described here, the same applies when the antiferromagnetic material such as Fe-Mn is used. The MR element portion 109 is shielded by the shield gaps 11 and 14,
5 and the like, the resistance change of the MR element section 109 is read by passing a current through the lead section 13.

Since the MR head is a read-only head, it is usually used in combination with an inductive head for writing. In FIG. 10, not only the reproducing head portion 32 but also the writing head portion 31 is depicted. FIG. 10 shows a case where the write head portion is further formed in FIG. As the write head portion, the upper recording core 1 formed on the upper shield 15 via the recording gap portion 40.
There is 6.

8 and 10 have described the conventional MR head structure using an abutted junction, the track width 41 can be regulated more precisely with the narrowing of the track due to the higher density. It is also effective to use the overlaid structure shown in FIG.

Next, the recording / reproducing mechanism of the MR head will be described with reference to FIG. As shown in FIG. 9, when recording, the magnetic flux generated by the current flowing through the coil 17
Leakage from between the upper core 16 and the upper shield 15 allows recording on the magnetic recording medium 21. The head unit 30 is
Since the magnetic recording medium 21 moves in the direction of the arrow c relative to the magnetic recording medium 21, by inverting the current flowing through the coil 17,
The direction 23 of recording magnetization can be reversed. Also,
Since the recording length 22 becomes shorter as the recording density becomes higher, the recording cap length 19 needs to be made smaller accordingly. When reproducing, the magnetic flux 24 leaking from the recording magnetized portion of the magnetic recording medium 21 acts on the MR element portion 109 sandwiched between the shields 10 and 15 to change the resistance of the MR element. M
Since a current is applied to the R element portion 109 via the lead portion 13, a change in resistance can be read as a change in voltage (output).

Considering the high density of the magnetic recording apparatus in the future, it is necessary to shorten the recording wavelength, and for that purpose, it is necessary to shorten the shield distance d (distance 18 in FIG. 9) shown in FIG. is there. For that purpose, as is clear from FIG.
It is necessary to reduce the total film thickness of the MR element portion 109, and it is desirable that the thickness of the MR element portion 109 is as thin as possible, and it should be 50 nm or less, preferably 30 nm or less.

Further, in the MR element section 109, the easy axis of magnetization of the free magnetic layer 1 in FIG. 1 is the signal magnetic field to be detected in the film plane in order to suppress the generation of Barkhausen noise at the time of reversing the magnetization of the soft magnetic film. It is preferable that the direction be substantially perpendicular to the direction. At this time, in order to cause a linear output change, it is necessary to fix the magnetization direction of the pinned magnetic layer 1 in the film surface in a direction perpendicular to the free magnetic layer 1.

FIG. 12 shows a shield type magnetic head using the MR element of the present invention, in which a current flows perpendicularly to the film surface. It has an upper shield 201 and a lower shield 202 made of a magnetic material, and the MR element 204 of the present invention is provided in the reproducing gap 203 of these two shield portions, and the electrode portions 205 and 206 are connected above and below the MR element 204. As a result, a current flows vertically to the film surface of the MR element 204. At this time, the electrode portions 2 provided above and below the MR element 204
05 and 206 are the upper shield 201 and the lower shield 20.
The upper and lower shields 201 and 202 may also be used as the electrode portions by connecting to the electrode 2. With this structure, it is possible to provide a magnetic head having a reproducing head portion which detects a signal magnetic field excellent in high output of the reproducing head portion corresponding to a narrower gap.

The MR film suitable for use at this time is TMR.
The element is effective. However, when the GMR film is used, the film resistance itself is small, so if the device size (here, track width × MR height) is 1 μm ² or more, the output is very small and not effective, but the narrow track due to higher recording density Since the resistance value itself increases when the element size becomes 0.01 μm ² or less due to the reduction of the bit length and the bit length, it is effective to use the GMR film in the magnetic head having the structure in which the current flows perpendicularly to the film surface.

In FIG. 12, for recording, a current is passed through the winding portion 207 to write a signal on a recording medium (not shown) by a leakage magnetic field from the recording gap 209 between the recording pole 208 and the upper shield 201, and recording is performed for reproduction. Medium (not shown)
This is performed by reading the signal magnetic field from the MR element 204 provided between the reproducing gap 203 (shield gap).

As an example of the magnetic head of the present invention, a yoke type head different from the shield type head shown in FIG. 9 is shown in FIG. Figure 1
3, the MR element portion 302 has a yoke portion 301 formed of a soft magnetic film that guides a signal magnetic field to be detected. Usually, the yoke portion 301 is a yaw composed of a soft magnetic film for guiding the signal magnetic field to be detected by the MR element portion A9.
In general, since the yoke part uses a conductive metal magnetic film, the insulating film 3 should not be shorted with the MR element part 302.
03 is provided. Also, this yoke type head is inferior in sensitivity to the shield type head of the type shown in FIG. 9 because it uses a yoke, but it is not necessary to place an MR element in the shield gap as shown in FIG. It is advantageous. Furthermore, since the MR element unit 302 is not exposed to the recording medium, when the reproducing head suddenly contacts the recording medium, or when a magnetic tape is used as the recording medium, for example, the tape and the reproducing head are brought into contact with each other, information is recorded. In the case of reading, it is superior to the shield type head in terms of reliability such as damage to the head and deterioration of characteristics due to wear.

It is possible to construct a magnetic recording device such as an HDD using the magnetic head having the reproducing head of the present invention. As shown in FIG. 14, the magnetic head 4 of the present invention.
01, the drive unit 402, the magnetic recording medium 403 for recording information, and the signal processing unit 404, it is possible to configure the magnetic recording device 400 excellent in high output.

Next, FIG. 16 shows an example of a magnetic random access memory (MRAM) using the MR element of the present invention as a memory element. The element used as the memory may have any configuration of the magnetic device having the above configuration. For example, as represented by A1 shown in FIG. 16, the elements are arranged in a matrix at the intersections of the sense lines 601 and the word lines 602 made of Cu or Al based on each line. Signal information is recorded by a two-current coincidence method using a synthetic magnetic field generated when a signal current is passed.

A basic example of the write operation and the read operation by the current of the magnetic memory device in FIGS. 17 to 19 will be described. In each figure, the magnetoresistive effect element shown in FIG. 1 is used as a memory element as an example. 17 to 19, the free magnetic layer 1 of FIG.
The nonmagnetic layer 1 and the pinned magnetic layer 1 are shown as a magnetoresistive effect element as a representative.

In FIG. 17, in order to read the magnetization state of each element individually, a switching element 7 represented by a FET is provided for each element.
A configuration in which 03 is provided is shown. This random access memory can be easily constructed on a CMOS substrate. Also in FIG.
Then, a non-linear element 704 (or rectifying element) for each element
A configuration using is shown. Here, the nonlinear element 704
Is a varistor, a tunnel element, or 3 of the above configuration.
You may use a terminal element. This random access memory can be manufactured on an inexpensive glass substrate only by increasing the film forming process of the diode. Further, in FIG. 19, the switch element 703 for element isolation as shown in FIGS. 17 and 18 or the non-linear element 704 is not used,
The element is arranged at the intersection of the direct word line 702 and the sense line / word line 701. Therefore, in FIG. 19, since a current flows across a plurality of elements at the time of reading, it is desirable that the number of elements is 10,000 or less in terms of reading accuracy. With 10,000 elements or more, sufficient output cannot be obtained.

In each of FIGS. 17 to 19, the bit line is used in combination with a sense line for reading a resistance change by passing a current through the element. However, in order to prevent malfunction due to the bit current and destruction of the element, the sense line is used. And the bit line may be separately provided. At this time, it is preferable that the bit line is arranged at a position electrically insulated from the element and parallel to the sense line. Further, in the case of current writing, it is desirable that the distance between the word line and the bit line and the memory cell is about 500 nm or less in terms of power consumption.

(Example 1) A Si substrate with a thermal oxide film was used as a substrate, and Cu, Ta, Ni-Fe, Co-Fe, Ru, Ir-Mn were used as targets.
A magnetoresistive effect element having the film structure shown in FIG. 4 was manufactured by the multi-source magnetron sputtering method using the 6 targets.

Example Sample a01: Si substrate / Ta (3) / Ni-Fe (t ₁ ) /
Ru (0.7) / Ni-Fe (t ₁ ) / Ir-Mn (12) / Co-Fe (3) / Cu (2.8) / Co-Fe
(1) / Ni-Fe (5) / Ta (3) For comparison, a sample shown in FIG. 2 having a conventional underlayer structure was prepared.

Conventional sample a02: Si substrate / Ta (3) Ni-Fe (t) / Pt
-Mn (15) / Co-Fe (3) / Cu (2.8) / Co-Fe (1) / Ni-Fe (5) / Ta (3) where the value in parentheses indicates the film thickness and the unit is nm. Is. Ni-F
The film compositions of e, Co-Fe and Ir-Mn alloys are Ni ₈₀ Fe ₂₀ and Co, respectively.
₉₀ Fe ₁₀ and Ir ₂₀ Mn ₈₀ (at%). For the underlayer of Samples a01 and a02, Ni-Fe having the same composition as that used in the free magnetic layer was used.
In each sample, Ta is stacked to a thickness of 3 nm on the film as a protective layer. The above sample is 1 × 10-8 Torr (1 Torr =
After evacuating to 133.322 Pa) or less, a film was formed by applying a magnetic field of about 100 Oe parallel to the substrate surface while flowing Ar gas at about 0.8 mTorr.

The MR characteristics of the MR ratio and the exchange coupling magnetic field (Hex) of the pinned magnetic layer were investigated by changing the thickness of the Ni—Fe layer of the underlayer of the sample a01 of the example and the sample a02 of the conventional example. For MR characteristics, the magnetic resistance was measured by the DC 4-terminal method with a maximum magnetic field of 5 kOe in the same direction as the applied magnetic field during film formation.

FIG. 20 shows the dependence of the MR ratio and the exchange coupling magnetic field (Hex) on the Ni—Fe underlayer thickness of the film configurations of the example sample a01 and the conventional example sample a02, respectively. Here, in the case of the example sample a01, the horizontal axis represents the value obtained by adding the film thicknesses of the two Ni—Fe layers forming the underlayer. The two Ni-Fe layers forming the underlayer of the example sample a01 have the same film thickness.

As can be seen from FIG. 20, Example sample a01
Also, the exchange coupling magnetic field (Hex) increases as the film thickness of NiFe of the underlayer of the conventional sample a02 increases. This is Ir-
It is considered that the crystal orientation of Mn is improved by the Ni-Fe underlayer, which corresponds to the increase in Hex of Ir-Mn / Co-Fe in both samples. On the other hand, the MR ratio
Comparing the dependence of the Ni-Fe underlayer thickness, in the case of the conventional sample a02, the Ni-Fe underlayer shows a maximum around 3 nm, and it decreases as the Ni-Fe underlayer becomes thicker. This decrease in MR ratio is due to current diversion loss to the Ni-Fe underlayer that does not contribute to GMR. On the other hand, in the case of the example sample a01, the MR ratio did not decrease even if the thickness of the Ni—Fe underlayer increased. It is considered that the GMR ratio is large because the two Ni-Fe layers forming the underlayer are oriented antiparallel to each other and the current shunt to the underlayer is suppressed as in the conventional sample a02. Moreover, when the Ni-Fe layer thicknesses of the underlayers of the example sample a01 and the conventional example sample a02 are the same, the MR element of the present invention has an MR ratio and an exchange coupling magnetic field (Hex) higher than those of the conventional underlayer structure. Also large and excellent M
It was found to have R characteristics.

(Example 2) A Si substrate with a thermal oxide film was used as a substrate, and Cu, Ta, Ni-Fe, Co-Fe, Ru, Pt-Mn were used as targets.
A magnetoresistive effect element having the film structure shown in FIG. 4 was manufactured by the multi-source magnetron sputtering method using the 6 targets.

Example sample b01: Si substrate / Ta (3) / Ni-Fe (2) / R
u (0.7) / Ni-Fe (2) / Pt-Mn (15) / Co-Fe (3) / Cu (3) / Co-Fe (1) /
Ni-Fe (5) / Ta (3) For comparison, the following samples having Ta underlayer and Ta underlayer / Ni-Fe underlayer were prepared.

Conventional sample b02: Si substrate / Ta (3) / Pt-Mn (15) /
Co-Fe (3) / Cu (3) / Co-Fe (1) / Ni-Fe (5) / Ta (3) Conventional sample b03: Si substrate / Ta (3) / Ni-Fe (3) / Pt-Mn (15) / Co-
Fe (3) / Cu (3) / Co-Fe (1) / Ni-Fe (5) / Ta (3) Here, the numerical value in parentheses represents the film thickness and the unit is nm. Ni-F
The film compositions of e, Co-Fe and Pt-Mn alloys are Ni ₈₀ Fe ₂₀ and Co, respectively.
₉₀ Fe ₁₀ , Pt ₄₈ Mn ₅₈ (at%). For the underlayer of Samples b01 and b03, Ni-Fe having the same composition as that used in the free magnetic layer was used.
In each sample, Ta is stacked to a thickness of 3 nm on the film as a protective layer. After evacuation of the vacuum chamber to 1 × 10-8 Torr or less, the sample was formed by applying a magnetic field of about 100 Oe parallel to the substrate surface while flowing Ar gas to about 0.8 mTorr. .

These samples were stored at 280 ° C. for 3 hours so that the Pt-Mn antiferromagnetic layer and the Co-Fe pinned magnetic layer generate an exchange coupling magnetic field.
Vacuum heat treatment was performed in a magnetic field of 5 kOe.

The magnetoresistive effect element thus produced was subjected to a magnetic field of maximum 5 kOe at room temperature to measure the magnetic resistance by the direct current 4-terminal method, and the MR ratio and the exchange coupling magnetic field (Hex) were investigated. The results are shown in Table 1.

[0070]

[Table 1]

As described above, it was found that the magnetoresistive effect element of the present invention has excellent MR characteristics as compared with the conventional element.

Next, X-ray diffraction was carried out to examine the crystal structure of the magnetoresistive film due to the difference in the underlying layers. Figure 21
Are X-ray diffraction profiles of samples b01 (Ta / Ni-Fe / Ru / Ni-Fe underlayer), b02 (Ta underlayer), and b03 (Ta / Ni-Fe underlayer). (111) of face-centered cubic structure of Pt-Mn antiferromagnetic layer
The diffraction angle corresponding to the surface appears in the vicinity of about 40 °, but almost no diffraction intensity can be obtained in the Ta underlayer sample b02. Ta /
It can be seen that in the sample b03 of the Ni-Fe underlayer and the sample b01 of the Ta / Ni-Fe / Ru / Ni-Fe underlayer, the diffraction intensity is very large and the crystal orientation of Pt-Mn is improved. Furthermore, these samples b01 and b
In 03, a strong diffraction intensity is also present near the diffraction angle of 44 °, but this is the peak corresponding to the face-centered cubic (111) plane of Cu, Ni-Fe, and Co-Fe films. -M
It was found that the n-spin valve film can obtain a film with a very good crystal orientation. Further, comparing the diffraction intensities of the sample b01 and the sample b03, it is found that the sample b01 of the present invention has excellent crystallinity because the diffraction intensity of the sample b01 is larger, and the superiority of the crystallinity of the film is as described above. It is considered to be one of the factors contributing to excellent MR characteristics.

Next, in order to examine the heat resistance of the samples b01 to b03 having the characteristics shown in Table 1, the samples were kept in a furnace heated to 300 ° C. for 100 hours, and then the MR ratio was examined at room temperature. The results are shown in Table 2.

[0074]

[Table 2]

As described above, it was found that the magnetoresistive effect element of the present invention exhibits thermally stable MR characteristics as compared with the conventional element.

(Example 3) A Si substrate with a thermal oxide film was used as a substrate, and Cu, Ta, Ni-Fe, Co-Fe, Ru and Pt-Mn were used as targets.
A magnetoresistive effect element having the film structure shown in FIG. 6 in which the pinned magnetic layer has a laminated ferri structure was manufactured by the multi-source magnetron sputtering method using the 6 targets of No.

Example sample c01: Si substrate / Ta (3) / Ni-Fe (2)
/Ru(0.7) / Ni-Fe (2) / Pt-Mn (15) / Co-Fe (3) /Ru(0.8) /
Co-Fe (3) /Cu(2.5) / Co-Fe (1) / Ni-Fe (3) / Cu (1) / Ta (3) Example sample c02: Si substrate / Ta (3) / Ni- Fe (1) /Ru(0.7) / Ni
-Fe (1) / Pt-Mn (15) / Co-Fe (3) /Ru(0.8) / Co-Fe (3) / Cu
(2.5) / Co-Fe (1) / Ni-Fe (3) / Cu (1) / Ta (3) An underlayer of Ta was further formed on the substrate side of the second underlayer ferromagnetic layer shown in FIG. .

For comparison, the following samples having Ta underlayer and Ta underlayer / Ni-Fe underlayer were prepared.

Conventional sample c03: Si substrate / Ta (3) / Pt-Mn (15)
/ Co-Fe (3) /Ru(0.8) / Co-Fe (3) /Cu(2.5) / Co-Fe (1) /
Ni-Fe (3) / Cu (1) / Ta (3) Conventional sample c04: Si substrate / Ta (3) / Ni-Fe (4) / Pt-Mn (15) /
Co-Fe (3) /Ru(0.8) / Co-Fe (3) /Cu(2.5) / Co-Fe (1) / Ni
-Fe (3) / Cu (1) / Ta (3) Here, the numerical value in parentheses represents the film thickness and the unit is nm. Ni-F
The film compositions of e, Co-Fe and Pt-Mn alloys are Ni ₈₀ Fe ₂₀ and Co, respectively.
₉₀ Fe ₁₀ , Pt ₄₈ Mn ₅₈ (at%). For the underlayer of Samples c01, c02, and c04, Ni-Fe having the same composition as that used in the free magnetic layer was used. Each sample had Cu of 1 nm and Ta as a protective layer on the top of the film.
Is stacked to 3 nm. The above sample is 1 × in the vacuum chamber
After evacuation to 10 ^-8 Torr or less, a magnetic field of about 100 Oe was applied parallel to the surface of the substrate while flowing Ar gas at about 0.8 mTorr to form a film.

These samples were kept at 280 ° C. for 5 hours so that the Pt-Mn antiferromagnetic layer and the Co-Fe pinned magnetic layer would generate an exchange coupling magnetic field.
Vacuum heat treatment was performed in a magnetic field of 5 kOe.

The MR element and the exchange coupling magnetic field (Hex) were examined by applying a magnetic field of 5 kOe at maximum at room temperature to the magnetoresistive element thus manufactured and measuring the magnetic resistance by the direct current 4-terminal method. The results are shown in Table 3.

[0082]

[Table 3]

In each sample, the pinned magnetic layer was made of Co-Fe / Ru / Co-Fe.
Of two Co laminated via Ru as a laminated ferri structure of
It can be seen that the exchange coupling magnetic field is higher than the Hex of the sample shown in Example 2 because the -Fe layer is antiferromagnetically coupled. Compared with the conventional sample c03 in which the underlayer is only Ta, the conventional sample c04 containing Ni-Fe in the underlayer has a large MR ratio and a large exchange coupling magnetic field (Hex) of the pinned magnetic layer. It was found that in b02, the MR ratio and Hex were improved and the MR characteristics were excellent. As shown in the results of Example 2, this is a layer that contributes to the GMR effect of Pt-Mn and Co-Fe, Cu, Ni-Fe, etc. laminated thereon by using Ni-Fe for the underlayer. It is considered that this is due to the improved crystal orientation of

In order to investigate the soft magnetic characteristics of the free magnetic layer (Co-Fe / Ni-Fe free magnetic layer in this embodiment), a magnetic field in which the magnetization direction of the pinned magnetic layer does not move, specifically, a magnetic field of 100 Oe is applied. A minor loop of magnetoresistance was measured by applying. FIG. 22 shows the minor loop of the magnetoresistance of the samples c01 to c04. In each magnetoresistance effect curve (minor loop), the magnetization direction of the pinned magnetic layer is fixed in the measurement magnetic field, and the resistance change corresponding to the magnetization reversal of the free magnetic layer (in FIG. 22, the vertical axis is represented by the MR ratio). Is shown. Therefore, from FIG. 22, the soft magnetic characteristics of the free magnetic layer of each sample, in particular, the magnitude of the coercive force and the symmetry of the magnetic field response thereof can be seen. Although the coercive force of the free magnetic layer of the conventional sample c03, which is the Ta underlayer, is as large as about 4 Oe, the coercive force of the example samples c01 and c02 containing Ni-Fe in the underlayer and the conventional sample c04 is 1 Oe or less. It can be seen that is extremely excellent in soft magnetic characteristics. However, the conventional sample c04
The magnetic field response is asymmetric due to the shape of the MR curve. On the other hand, in the case of the example samples c01 and c02, the shape of the MR curve is excellent in symmetry, and the response of the free magnetic layer to the external magnetic field is good. Further, it can be seen that the MR curve of the conventional sample c04 deviates from the zero magnetic field to the negative side more than that of the example samples c01 and c02 and the conventional sample c03. This difference is that the sample samples c01 and c02 containing two layers of Ni-Fe in the underlayer are antiparallel to each other via Ru, and there is almost no leakage magnetic field from the underlayer or very little. It is thought to be due to. Therefore, it was found that it is possible to obtain an element exhibiting excellent MR characteristics by using the underlayer of the present invention for the spin valve film.

The above sample (after vacuum heat treatment in a magnetic field of 280 ° C.)
In order to investigate the heat resistance of the, heat treatment was performed up to 400 ° C.
In the heat treatment process, the temperature is raised from room temperature to each target temperature over about 3 hours, maintained at the target temperature for 1 hour, then cooled down to room temperature over 5 hours, and then MR The ratio was measured. Table 4 shows the result.

[0086]

[Table 4]

As described above, it was found that the magnetoresistive effect element of the present invention is very excellent in thermal stability as compared with the conventional element. In particular, it is considered that one of the causes is that the decrease in the MR ratio of the conventional sample samples c03 and c04 corresponds to the decrease in the heat treatment temperature of the exchange coupling magnetic field (Hex) of the pinned magnetic layer. To be On the other hand, the magnitudes of the exchange-coupling magnetic fields of the samples c01 and c02 of the present embodiment hardly change even when the heat treatment temperature rises, and the magnetoresistive effect element of the present invention has a thermal effect on the magnetic structure of the pinned magnetic layer. It was found that the stability was excellent.

(Example 4) A Si substrate with a thermal oxide film was used as a substrate, and Cu, Ta, Ni-Fe, Co-Fe, Ru, Al and Pt were used as targets.
A magnetoresistive element having the film structure shown in FIG. 6 in which the pinned magnetic layer has a laminated ferri structure was manufactured by a multi-source magnetron sputtering method using -Mn. First, Ta (3nm) / Cu for the lower electrode
A (50 nm) film was formed, and a magnetoresistive film having the following film structure was formed on the film.

Example Sample d01: Ta (3) / Ni-Fe (2.5) / Ru
(0.8) /Ni-Fe(2.5) / Pt-Mn (15) / Co-Fe (3) /Ru(0.8) / C
o-Fe (3) /Al-O(1.0) / Co-Fe (1) / Ni-Fe (3) / Ta (15) For comparison, the Ta underlayer and Ta underlayer / Ni-Fe underlayer below A magnetoresistive element having a film structure was produced.

Conventional sample d02: Ta (3) / Pt-Mn (15) / Co-F
e (3) /Ru(0.8) / Co-Fe (3) /Al-O(1.0) / Co-Fe (1) / Ni-F
e (3) / Ta (15) Conventional sample d03: Ta (3) / Ni-Fe (3) / Pt-Mn (15) / Co-Fe
(3) /Ru(0.8) /Co-Fe(3)/Al-O(1.0) / Co-Fe (1) / Ni-Fe
(3) / Ta (15) Here, the numerical value in parentheses represents the film thickness, and the unit is nm. Ni-F
The film compositions of e, Co-Fe and Pt-Mn alloys are Ni ₈₀ Fe ₂₀ and Co, respectively.
₇₅ Fe ₂₅ , Pt ₄₈ Mn ₅₈ (at%). For the underlayer of sample d01, Ni-Fe having the same composition as that used for the free magnetic layer was used. Ta (15 nm) is laminated as a protective layer for the film of each sample. Ta (15 nm) / Cu (50 nm) / Ta (3 nm) was formed as an upper electrode on the film of each sample. The sample above is 1 × 10 ^-8 Torr in a vacuum chamber.
After evacuation to the following, film formation was performed while Ar gas was caused to flow at about 0.8 mTorr. The value in brackets of Al-O is
Shows the total value of the design film thickness of Al before oxidation treatment.
After forming 0.3-0.7nm of film in an atmosphere containing oxygen of 200 Torr 1
Oxidation for minutes was repeated. The above magnetoresistive effect element is subjected to fine processing into a mesa type shown in FIG. 15 by using photolithography, and the periphery is insulated by using Al ₂ O ₃ as an interlayer insulating film, and then a through hole is opened, and a through hole is formed on this.
An upper electrode of Cu (50 nm) / Ta (3 nm) was formed to fabricate a magnetoresistive effect element. The element had a sample area of 1 μm × 1.5 μm.

These samples were prepared so that the Pt-Mn antiferromagnetic layer and the Co-Fe pinned magnetic layer generate an exchange coupling magnetic field.
Vacuum heat treatment was performed in a magnetic field of 5 kOe at 0 ° C for 5 hours.

The MR ratio of the magnetoresistive element thus produced was measured by applying a magnetic field of 1 kOe at maximum at room temperature and measuring the magnetoresistance by the direct current 4-terminal method. Further, these magnetoresistive effect elements were heat-treated up to 400 ° C., and after each heat-treatment temperature, magnetoresistive measurement was performed at room temperature. The results are shown in Table 5. For heat treatment at 300 ° C or higher, raise the temperature from room temperature to the target temperature over about 3 hours, maintain the temperature at the target temperature for 1 hour, and then lower the temperature to room temperature over 5 hours. The MR ratio was measured at room temperature.

[0093]

[Table 5]

As described above, it was found that the magnetoresistive effect element (Example d01) of the present invention was excellent in thermal stability as compared with the conventional element. Conventional Example Samples Samples d02 and d03 correspond to the decrease in the MR ratio due to the increase in the heat treatment temperature as the heat treatment temperature of the exchange coupling magnetic field (Hex) of the pinned magnetic layer decreases as shown in Example 3. It is thought that the cause is that On the other hand, the magnitude of the exchange-coupling magnetic field of the sample d01 of this example hardly changes even when the heat treatment temperature rises, and the magnetoresistive effect element of the present invention is thermally stable against the magnetic structure of the pinned magnetic layer. It turned out that it is excellent in sex.

(Embodiment 5) The above-mentioned embodiment sample b01 and conventional
An example sample b03 is used as the MR element 109 and shown in FIG.
Such an MR head was constructed and the characteristics were evaluated. This place
If the substrate is Al₂O ₃-TiC substrate used, upper recording core
16, shield 10, 15 material is Ni_0.8Fe_0.2Alloy
Made with Al, and the shield gaps 11 and 14 are made of Al₂O₃To
Using. The hard bias portion 12 is made of Co-Pt alloy.
The lead portion 13 was made of Au.

Further, the direction of the easy magnetization axis of the fixed layer is parallel to the signal magnetic field direction to be detected so that the easy magnetization direction of the free magnetic layer is perpendicular to the signal magnetic field direction to be detected (track width direction). Thus, the magnetic film was provided with anisotropy. After making a magnetoresistive element, this method
After heat treatment at 0 ° C. to define the easy direction of the pinned magnetic layer, heat treatment was further performed at 200 ° C. to specify the easy axis of the free layer.

The track width of the magnetoresistive effect element of the reproducing head portion 32 was 0.5 μm, and the MR height was 0.5 μm. A test was conducted in which the manufactured head was placed in a constant temperature bath at 150 ° C. and kept for 10 days while a direct current of 10 mA was applied. The output before and after this test was compared. As a result, in the head using the example sample b01 of the present invention, the output decrease was about 1.3% and showed very stable output characteristics, whereas the output decrease of the head using the conventional example sample b03 A very large output reduction of about 43% was observed.

(Example 6) Using the GMR film having the film structure of the example sample c01 produced in the example 3 and the conventional example sample c03, FIG.
The magnetic head having the yoke structure shown in FIG. As the insulating film 303, an Al oxide produced by a plasma oxidation method was produced. A high magnetic permeability CoNbZr-based amorphous alloy film was used for the yoke portion 301, and a Ni—Fe plated film was used for the recording pole portion 304. Further, the direction of the easy axis of magnetization of the fixed layer is parallel to the signal magnetic field direction to be detected so that the direction of easy magnetization of the free magnetic layer is perpendicular to the signal magnetic field direction to be detected (the direction perpendicular to the paper surface in FIG. 13). Anisotropy was imparted to the magnetic film so that it was parallel to the line connecting the two yoke portions 301 shown in FIG. In this method, after creating a magnetoresistive element, first heat-treat it in a magnetic field at 280 ° C to define the easy direction of the pinned magnetic layer, and then heat it at 200 ° C to define the easy axis of the free layer. I went.

The magnetic resistance was measured in order to investigate the output characteristics of the head thus manufactured. Figure 23 shows sample c0
The magnetoresistive curve with respect to the standardized output of each head using the film structure of 1 and c03 is shown.

As can be seen from FIG. 23, the operating point center Hd of the head using the conventional sample c03 of the Ta / Ni—Fe underlayer (see FIG.
Is about 100 Oe, whereas Ta / of the present invention
It was found that the center of the operating point of the head using the example sample c01 of the Ni-Fe / Ru / Ni-Fe underlayer was reduced to 50 Oe. This is because the deviation of the operating point of the free layer due to the leakage magnetic field from the underlayer Ni-Fe of the conventional sample c03, as in the underlayer of the present invention,
It was found that the structure such as Ta / Ni-Fe / Ru / Ni-Fe can reduce the leakage magnetic field from the underlayer and reduce the operating point of the head, which is very effective. When the underlayer has a magnetic layer having an fcc (111) orientation such as Ni-Fe as described above, an appropriate non-magnetic layer for exchange coupling such as Ru is used as in the present invention to remove the magnetic layer from the underlayer. It is possible to reduce the leakage magnetic field and improve the operating point center (bias magnetic field) in the head state.

Example 7 A magnetoresistive effect memory element was produced using the example sample d01 produced in Example 4 and the conventional example samples d02 and d03. First, a word line 70 made of Cu shown in FIG. 17 is formed on a Si substrate having a 3000 Å thermally-oxidized SiO2 film.
2 was formed, and an Al2O3 insulating film was formed to form a sense line 700 made of Cu. Here once CMP
After smoothing the surface with, a TMR film was prepared. First, at this stage, heat treatment was carried out at 280 ° C. for 5 hours in a magnetic field of 5 kOe so that the Pt-Mn and the pinned magnetic layer generate an exchange coupling magnetic field. Next, a TMR element was manufactured by the method shown in Example 4. Finally, a sense line / word line 701 is formed as an upper electrode of the TMR element to form a switch element 703 as shown in FIG.
A single memory device without was fabricated. An electric current is applied to the word line 702 and the sense line / word line 701 to generate a magnetic field, and the free magnetic layer 1 (Co-F in this embodiment) of the magnetoresistive element is produced.
Information "0" was recorded by reversing the magnetization direction of the e (1 nm) / Ni-Fe (3 nm) film). Next, a current was applied to the word line 702 and the sense line / word line 701 in the opposite direction to the above to generate a magnetic field to cause magnetization reversal of the free magnetic layer 1 to record information "1". A bias voltage was applied between the sense line 700 and the sense line / word line 701 to flow a sense current, and the element voltages in the state of information "0" and information "1" were measured. The magnetic memory devices using the samples d02 and d03 obtained the same output difference. Therefore, it was found that the three magnetic memories thus manufactured have a memory function with the free magnetic layer 1 as an information recording layer.

Next, an integrated memory was produced by using these elements on a CMOS substrate with a memory element having a basic structure as shown in FIG. The device array has a total of 8 blocks, with 16 × 16 device memory as one block. First, CMOS is arranged on a matrix by using FET as a switching transistor (SW-Tr), and the surface is flattened by CMP. Then, the TMR elements of the example sample d01 and the conventional example sample d02 produced in Example 4 are formed into the CMOS. Correspondingly, it was provided like a matrix. The element cross-sectional area of each sample was 0.1 μm × 0.15 μm. The remaining one element in each block was a dummy element for canceling the wiring resistance, the element minimum resistance, and the FET resistance. Note that Cu was used for all the word lines and bit lines. A magnetic random access memory as shown in FIGS. 16 and 17 was formed, and finally hydrogen sintering treatment was performed at 400 ° C.

8 due to the combined magnetic field of the word line and the bit line
Magnetization reversal of each free magnetic layer (Co-Fe (1 nm) / Ni-Fe (3 nm) film in this case) was simultaneously performed on 8 elements of one block, and signals of 8 bits each were recorded. Next, the FET gate made of CMOS was turned on one by one for each block, and a sense current was passed. At this time, the voltage generated in the bit line, the element and the FET in each block was compared with the dummy voltage by the comparator, and 8-bit information was read simultaneously from the output voltage of each element. As a result, in the MRAM using the example sample d01, the element output was obtained as in the case of the single magnetic memory element.
The MRAM using d02 and d03 gave almost no output. It is considered that this is because the element of the present invention can withstand the hydrogen sintering treatment at 400 ° C., but the conventional element cannot.

At least two underlayer ferromagnetic layers forming the underlayer of the magnetoresistive effect element of the present invention shown in Examples 1 to 7 are representative of Ni ₈₀ Fe ₂₀ (at%) composition films. As disclosed, Ni _x Co _y Fe having fcc (face centered cubic) structure
_z (0.6≤x≤0.9, 0≤y≤0.4, 0≤z≤0.3) or Ni _{x '
Co y 'Fe z' (0} ≦ x '≦ 0.4,0.2 ≦ y' ≦ 0.95,0 ≦ z '≦ 0.5)
Or Ni _x Fe _1-x (0.6 ≦ x ≦ 1) or Co _y Fe _1-y (0.7
≤ y ≤ 0.95), and at least one of Ru, Ir, Rh, Re, Cu and Cr is used as the underlying non-magnetic layer laminated between at least two underlying ferromagnetic layers. The same effect can be obtained by forming the base layer by using.

[0105]

As described above, in the magnetoresistive effect element of the present invention, two magnetic layers are laminated on the underlayer via the nonmagnetic layer to reduce the leakage magnetic field from the magnetic layer forming the underlayer. , Stabilizes the magnetic field direction of the free magnetic layer and the pinned magnetic layer,
It is possible to provide a magnetoresistive effect element having improved output stability and very stable characteristics with respect to a high temperature thermal process. Further, with such a structure of the underlayer, the exchange coupling magnetic field characteristics between the antiferromagnetic layer and the pinned magnetic layer can be improved. When a magnetoresistive head is used for the MR element of the present invention, the bias characteristic of the head can be improved and improved as compared with the conventional case, and high density magnetic recording can be performed. Further, it becomes possible to provide a high output and thermally stable high density magnetic memory (MRAM) using the MR element of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a magnetoresistive effect element according to an embodiment of the present invention.

FIG. 2 is a schematic view of a cross section of a conventional magnetoresistive effect element using a Ta / Ni-Fe underlayer.

FIG. 3 is a perspective view of the magnetoresistive effect element of the present invention shown in FIG.

FIG. 4 is a perspective view of a conventional magnetoresistive effect element using the Ta / Ni—Fe underlayer shown in FIG.

FIG. 5 is a schematic sectional view of a magnetoresistive effect element of the present invention.

FIG. 6 is a schematic view of a cross section of a magnetoresistive effect element of the present invention.

FIG. 7 is a perspective view of an MR head according to an embodiment of the present invention.

FIG. 8 is a diagram showing an example of a magnetoresistive head according to an embodiment of the present invention.

FIG. 9 is a sectional view of an MR head and a magnetic disk according to an embodiment of the present invention.

FIG. 10 is a cross-sectional view of a recording head integrated MR head according to an embodiment of the present invention.

FIG. 11 is a sectional view of an MR head according to another embodiment of the present invention.

FIG. 12 is a diagram showing an example of a shield type magnetoresistive head of the present invention.

FIG. 13 is a diagram showing an example of a yoke type magnetoresistive head of the present invention.

FIG. 14 is a plan view of a hard disk device according to an embodiment of the present invention.

FIG. 15 is a schematic view of a cross section of the magnetoresistive effect element of the present invention in which electrodes are provided above and below the element.

FIG. 16 is a diagram showing an example of a magnetic memory element of the present invention.

FIG. 17 is a diagram of a basic example of a write operation and a read operation of the magnetic memory element of the present invention.

FIG. 18 is a diagram of a basic example of a writing operation and a reading operation of the magnetic memory element of the present invention.

FIG. 19 is a diagram showing a basic example of a write operation and a read operation of the magnetic memory element of the present invention.

FIG. 20 is the Ni of the magnetoresistive effect element sample shown in Example 1;
-Fe underlayer and MR ratio to Ni-Fe underlayer thickness for Ni-Fe / Ru / Ni-Fe underlayer and exchange coupling magnetic field (Hex) of fixed layer
Diagram showing the relationship between

FIG. 21: X of the magnetoresistive effect element sample shown in Example 2
Diagram showing line diffraction profile

FIG. 22 is a diagram showing a magnetoresistance curve (minor curve) of the magnetoresistance effect element sample shown in Example 3;

FIG. 23 is a diagram showing a magnetoresistive curve of the yoke-type head manufactured in Example 6;

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 10/32 H01L 27/10 447 H01L 27/105 G01R 33/06 RF term (reference) 2G017 AA01 AD55 AD65 5D034 AA02 BA03 BB08 5E049 AA01 AA04 AA07 AA09 AC00 AC05 BA06 BA12 CB02 DB12 5F083 FZ10 GA11 GA12 JA36 JA37 JA38 JA56 PR03 PR21 PR22 PR23

Claims (16)

[Claims] 1. A structure in which at least an antiferromagnetic layer, a pinned magnetic layer, a first nonmagnetic layer, and a free magnetic layer are laminated on a substrate in this order from the substrate side, and the pinned magnetic layer is the antiferromagnetic layer. Magnetically coupled and does not rotate easily with respect to an external magnetic field, the free magnetic layer easily rotates with an external magnetic field, and the difference in relative angle between the magnetization directions of the fixed layer and the free magnetic layer. In the magnetoresistive effect element having a different resistance value, there is an underlayer containing at least one underlayer nonmagnetic layer and at least two underlayer ferromagnetic layers between the antiferromagnetic layer and the substrate, The underlayer includes at least one multilayer film composed of first and second underlayer ferromagnetic layers laminated with a first underlayer nonmagnetic layer interposed therebetween, and the underlayer and the antiferromagnetic layer are in contact with each other. And a magnetoresistive effect element. 2. The magnetoresistive effect element according to claim 1, wherein the first underlying ferromagnetic layer is in contact with the antiferromagnetic layer. 3. The first and second underlayer ferromagnetic layers stacked via the first underlayer nonmagnetic layer are antiferromagnetically exchange-coupled, and the first underlayer nonmagnetic layer is Ru, Ir, Rh, R
2. A material containing any one of e, Cu and Cr.
Alternatively, the magnetoresistive effect element according to the item 2. 4. When the saturation magnetizations of the first and second underlayer magnetic layers are M ₁ and M ₂ and the film thicknesses are t ₁ and t ₂ , respectively, the respective products M ₁ × t ₁ and M ₂ × The magnetoresistive effect element according to claim 1, wherein t ₂ is substantially the same. 5. The magnetoresistive effect element according to claim 1, wherein the underlayer magnetic layer forming the underlayer contains Ni, a Ni—Fe alloy, or a Co—Fe alloy. 6. The magnetoresistive effect according to claim 1, wherein the underlayer magnetic layer forming the underlayer is made of the same material as the pinned magnetic layer or the free magnetic layer. element. 7. The underlayer has a structure in which a second underlayer nonmagnetic layer, a second underlayer magnetic layer, a first underlayer nonmagnetic layer, and a first underlayer magnetic layer are stacked in this order from the substrate side. The underlayer nonmagnetic layer is made of at least one selected from Ta, Hf, Zr, Ti, W, Nb, Pt, Cr, Au, and Cu.
7. The magnetoresistive effect element according to any one of 1 to 6. 8. The antiferromagnetic layer is an A-Mn alloy (provided that A
Is at least one element selected from Pt, Ni, Pd, Cr, Rh, Re, Ir, and Ru).
Alternatively, the magnetoresistive effect element according to the item 2. 9. The pinned magnetic layer further includes a nonmagnetic layer for exchange coupling, a first magnetic layer and a second magnetic layer antiferromagnetically exchange coupled via the nonmagnetic layer for exchange coupling, The magnetoresistive effect element according to claim 1, wherein the non-magnetic layer for exchange coupling contains any one of Ru, Ir, Rh, Re, Cu, and Cr. 10. The non-magnetic layer constituting the magnetoresistive effect element according to claim 1, wherein Cu, Ag, Au,
A magnetoresistive effect element characterized by being Cr or Ru. 11. The nonmagnetic layer constituting the magnetoresistive element according to claim 1, wherein the nonmagnetic layer is an Al oxide,
A magnetoresistive effect element characterized by being a nitride or an oxynitride. 12. An electrode layer is arranged above and below a film surface of the magnetoresistive effect element according to claim 1.
A magnetoresistive effect element characterized in that a current is caused to flow perpendicularly to the film surface. 13. A magnetoresistive head comprising the magnetoresistive element according to claim 1 and a shield portion. 14. A magnetoresistive head comprising the magnetoresistive element according to claim 1 further comprising a yoke for introducing a magnetic field to be detected into the magnetoresistive element section. 15. A magnetic recording device using the magnetoresistive head according to claim 13. 16. A magnetoresistive effect element according to claim 1, further comprising an information reading conductor line (sense line) portion for further reading information, and an information recording conductor for recording information. A magnetoresistive effect memory element comprising a wire (word wire portion).