JPH1187800A - Magnetoresistive effect element and magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent change ratio of reluctance from dropping, by providing a laminate unit film of artificial grids including a ferromagnetic film of alloy containing Ni and a separation film adjacent to the ferromagnetic film wherein the separation film of the laminate unit film comprises W or W-containing alloy. SOLUTION: A magnetoresistive element 1 comprises an antiferromagnetic film 4 formed on a substrate 6 by spattering or the like. Then, a ferromagnetic film 2 of Ni-Fe alloy is formed on an upper face of the antiferromagnetic film 4. Further, a separation film 3 of W or alloy mainly containing W is formed on an upper face of the ferromagnetic film 2. In addition, the ferromagnetic film 2 is formed on an upper face of the separation film 3. An artificial grid of the four laminated films is constructed as a single laminate unit film 5. The magnetoresistive element 1 controls an orientation of magnetization between adjacent magnetic films. That is, the ferromagnetic film 2 is placed adjacent to the antiferromagnetic film 4, thereby generating a single direction biasing magnetic field by exchange bonding between the films.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-resistance effect element used for a magnetic sensor, a magnetic head and the like.
In particular, the present invention relates to a magnetoresistance effect element having an artificial lattice film in which a magnetic film and a separation film (a non-magnetic conductive film) are stacked.

[0002]

2. Description of the Related Art When a magnetic field is applied, the electric resistance changes, and as a magnetoresistive element (MR element) capable of detecting the intensity of the magnetic field, a magnetoresistive change rate (MR ratio) has conventionally been used.
Of permalloy (NiFe) of about 3% has been used. In recent years, the magnetoresistive effect film of an artificial lattice film in which a magnetic film and a non-magnetic film are laminated has a larger MR ratio.
It has attracted attention as an R element material. However, there are various problems inherent in stacking this film.

As a prior art related to the present invention, there is a magnetoresistive element 50 shown in FIG. Magnetically soft Ni is frequently used as a magnetic material of the magnetic film 51 in the magnetoresistive element 50. For example, a Ni—Fe alloy is used as a magnetic material for a magnetic sensor or a magnetoresistive element of a magnetic head.

The magnetoresistance effect element 50 has a plurality of magnetic films 51 laminated to improve the magnetoresistance ratio. In the magnetic film 51, a separation film 52 which is a non-magnetic conductive film is laminated in the middle due to spin-dependent scattering and the like. In the separation film 52, Cu is frequently used mainly because of its non-magnetic conduction characteristics.

However, the magnetic film 5 made of a Ni—Fe alloy
1 and the Cu separation film 52 are stacked at a high temperature.
Diffusion at the stacked interface between NiFe and Ni-Fe
It has been found that the soft magnetic properties of the alloy layer deteriorate and the rate of change in magnetoresistance decreases, which is a problem.

The high temperature state of the magnetoresistive element 50 is as follows. One of them is a manufacturing process of the magnetoresistive element 50. In other words, it is heated in the heat treatment step in the manufacturing process, and the soft magnetic property is deteriorated. Then, the rate of change in magnetoresistance decreases.

Second, the magnetoresistance effect element 50 is used for applications involving heat, and the rate of change in magnetoresistance is reduced by heat. Incidentally, 53 is a substrate.
Reference numeral 64 denotes a bias magnet.

FIG. 21 is a perspective view of a magnetic sensor in a flat ignition device in an internal combustion engine of an automobile or the like.
In FIG. 21, one end of a shaft 61 is provided on both sides with a rotor gear 62 having small teeth 63 formed on its peripheral surface. A cylindrical bias magnet 64 is connected between the two rotor gears 62.

Further, a yoke 65 facing the small teeth 63 of the rotor gear 62 is formed in a U shape, and a detection coil 66 is provided in the middle of the yoke 65. The detection coil 66 picks up a reactance change in the magnetic circuit.

[0010] As described above, it is recognized that the performance of an engine used in an application involving heat, such as an internal combustion engine, is reduced by the influence of heat. Further, in a configuration in which the bias magnet 64 is rotated, it is difficult to mount the element, and there is a problem in utilizing the device in a high-speed rotation state.

Further, in an artificial lattice film in which a ferromagnetic film, a separating film and an antiferromagnetic film are laminated on the magnetoresistive element 50, the separating film is made of Cu and the antiferromagnetic film is made of M
In the case of an n-Fe alloy, corrosion resistance is a problem. In particular, when high temperatures are involved, it is recognized that the corrosion resistance further decreases.

[0012]

As described above, since the magnetoresistance effect element 50 has a small magnetoresistance change rate by itself as a magnetic film, it is attempted to improve the magnetoresistance change rate by constructing it as an artificial lattice film. I have. However, in the process of manufacturing an artificial lattice film, since a heat treatment process is always involved, Ni-
Cu-NiFe with Fe alloy ferromagnetic film and Cu separation film
The soft magnetic characteristics of the Ni—Fe alloy deteriorate due to the diffusion at the lamination interface between them.

For example, when manufacturing a hard disk, a heat treatment step is always included. Therefore, a problem arises in laminating the Cu separation film and the magnetic film of the Ni—Fe alloy. In addition, there is a problem in that the corrosion resistance is reduced even in the case of laminating a Cu separation film and an antiferromagnetic Mn-Fe alloy.

Furthermore, when the sensor is used for a sensor such as a wheel speed of an internal combustion engine with the progress of car electronics, the magnetoresistance effect element 50 is thermally affected, so that the magnetoresistance change rate is reduced.

The present invention has been made in view of the above problems, and a technical problem thereof is to prevent a rate of change in magnetoresistance in a manufacturing process of a magnetoresistance effect element from being reduced. is there. In addition, while exhibiting heat resistance even when thermally affected in the application of the magnetoresistive effect element,
It is to prevent the rate of change in magnetoresistance from decreasing.

[0016]

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and the technical means thereof are configured as follows.

According to the first aspect of the present invention, there is provided a ferromagnetic film (2) of an alloy containing Ni and a separation film (3) adjacent to the ferromagnetic film (2).
And a laminated unit film (5) of an artificial lattice containing at least the following: wherein the separation film (3) of the laminated unit film (5) is made of W or an alloy containing W.

According to a second aspect of the present invention, the ferromagnetic film (2) is N
2. The magnetoresistive element according to claim 1, wherein the element is an i-Fe alloy.

According to a third aspect of the present invention, the laminated unit film (5) has an antiferromagnetic film (4), a ferromagnetic film (2), a separation film (3) and a ferromagnetic film (2) in a laminated structure. With ferromagnetic film (3)
Is made of an alloy containing Ni as a main component.
3. The magnetoresistive effect element according to item 1.

According to a fourth aspect of the present invention, the ferromagnetic film (2) is N
4. The magnetoresistive element according to claim 3, wherein the element is an i-Fe alloy and the separation film is W.

The invention according to claim 5 is the magnetoresistance effect element according to claim 3 or 4, wherein the antiferromagnetic film (4) is made of α-Fe ₂ O _3, NiO, a FeMn alloy or a PtMn alloy.

According to a sixth aspect of the present invention, the antiferromagnetic film (4) is made of Ru, Zr, Nb, Ge, V, Co, H
5. The magnetoresistive element according to claim 3, wherein the element contains at least one element selected from the group consisting of f, Pt, and Pd.

According to a seventh aspect of the present invention, there is provided an artificial lattice in which the laminated unit film (5) is formed by laminating a separation film (3), a ferromagnetic film (2), a separation film (3) and a ferromagnetic film (2). The magnetoresistive element is configured such that the ferromagnetic film (2) is an alloy mainly composed of Ni and the separation film (3) is an alloy mainly composed of W.

According to an eighth aspect of the present invention, the laminated unit film (5) comprises a separation film (3), a ferromagnetic film (2), an antiferromagnetic film (4), a separation film (3) and a ferromagnetic film (2). ) Are laminated, and the ferromagnetic film (2) is an alloy containing Ni and the separation film (3) is an alloy containing W as a main component.

According to a ninth aspect of the present invention, a ferromagnetic film (2) of an alloy containing Ni and a separation film (3) of W or an alloy containing W as a main component adjacent to the ferromagnetic film (2) are laminated. The magnetoresistive effect element (1) having the artificial lattice
This is a magnetic sensor provided with 5).

[0026]

According to the present invention, there is provided a magnetoresistance effect element comprising a ferromagnetic film (2)
Can be made a Ni-based alloy to improve the magnetoresistance ratio. At the same time, the ferromagnetic film (2) of the Ni-based alloy can be formed on the artificial lattice film to further improve the magnetoresistance ratio, but the ferromagnetic film (2) and the separation film ( By making 3) a W or W alloy, the magnetoresistance ratio can be maintained at almost the normal temperature state without substantially lowering even if it is affected by heat.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetoresistive element according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a magnetoresistive element according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a magnetoresistive element (MRE). The magnetoresistive element 1 is composed of α-Fe ₂ O ₃ , NiO, FeMn alloy, NiMn alloy or PtMn alloy on a substrate 6 made of glass, ceramics such as Al ₂ O ₃ —TiC, magnesium oxide, insulated Si or the like. Is formed by a sputtering method or the like. Next, the antiferromagnetic film 4
A ferromagnetic film 2 of a Ni—Fe alloy is formed on the upper surface of the substrate by a similar manufacturing method. Further, on the upper surface of the ferromagnetic film 2, a separation film (nonmagnetic conductive film) 3 of W or an alloy containing W as a main component is formed. The above-described ferromagnetic film 2 is formed on the upper surface of the separation film 3. The artificial lattice of the four stacked films is configured as one stacked unit film 5. The laminated unit film 5 may be laminated two or more times to form the magnetoresistive element 1 having an artificial lattice.

This magnetoresistive element 1 is a method of controlling the direction of magnetization between adjacent magnetic films. That is, the ferromagnetic film 2 and the antiferromagnetic film 4 are adjacent to each other, and a one-way bias magnetic field is generated between the films by exchange coupling. This is a so-called spin valve film.

As one embodiment of the magnetoresistive film 1, a ferromagnetic film 2 is made of 81 wt% Ni—Fe alloy, an antiferromagnetic film 4 is made of NiO alloy, and a separating film 3 is made of W. As described above, the effect element 1 was sequentially laminated on the antiferromagnetic film 4, the ferromagnetic film 2, the separation film 3, and the ferromagnetic film 2 on the substrate 6 to form an artificial lattice film. The N of the ferromagnetic film 2
The thickness of the i-Fe alloy was determined to be 10 nm because it was found that 5 to 15 nm was an appropriate size. Further, the thickness of the NiO alloy of the antiferromagnetic film 4 was determined to be 30 to 70 nm, which was determined to be an appropriate size, so that the thickness was set to 50 nm.
Further, the thickness of W of the separation membrane 3 was determined to be 1 to 15 nm, which was an appropriate dimension. This magnetoresistive element 1a is before the heat treatment.

The magnetoresistive element 1a is shown in FIG.
The electrical resistance was measured by the test method using a vibration sample magnetometer shown in FIG. Since the electric resistance value R is V ÷ I, the electric resistance value R is measured by bringing four pins 10 into contact with the upper surface of the magnetoresistive element 1a. At this time, the magnet is approached from both sides.

FIG. 3 shows an MH hysteresis characteristic diagram of the results of this experiment. Note that M = magnetization and H = external magnetic field. FIG. 4 shows a ΔR / RH history characteristic diagram of the experimental result. Note that ΔR / R = magnetic resistance change rate R = electric resistance value ΔR = Rmax−Rmin = magnetic resistance change value H = external magnetic field.

As a comparative example, a magnetoresistive element 1b having the same structure as above before the heat treatment was manufactured, and only the separation film 2 was a Cu film. The MH hysteresis characteristic diagram obtained by measuring the magnetoresistance effect element 1a with the same tester under the same conditions as the above-described present invention is as shown in FIG.

FIG. 6 shows the ΔR / RH history characteristic of the magnetoresistive element 1b measured under the same conditions as described above.

FIG. 3 of the magnetoresistive element 1a of the present invention.
And MH history characteristic diagram shown in FIG. 4 and ΔR / R−
H history characteristic diagram, MH history characteristic diagram of comparative example, and Δ
Comparing with the R / RH history characteristic diagram, the magnetoresistance effect element 1a of the present invention has a magnetoresistance change rate of about 5%, whereas the magnetoresistance effect element 1b of the comparative example has a magnetoresistance change rate of about 5%. 4
%.

Next, the above-described magnetoresistive element 1a of the present invention and the magnetoresistive element 1b of the comparative example were heated at 350 ° C. in a vacuum, and this heating was continuously performed for 3 hours.

FIG. 7 shows the relationship between the external magnetic field and the rate of change of the magnetoresistance of the magnetoresistance effect element 1a after the heat treatment according to the present invention. The ΔR / RH history characteristic diagram obtained by measuring the heat-treated magnetoresistive element 1a of the present invention with the same tester under the same conditions as the magnetoresistive element 1a before the heat treatment is as shown in FIG. is there.

FIG. 8 shows the relationship between the external magnetic field and the rate of change in magnetoresistance of the magnetoresistance effect element 1b after heat treatment of the comparative example. Heat-treated magnetoresistive element 1 of this comparative example
FIG. 8 shows a ΔR / RH history characteristic diagram obtained by measuring b with the same tester under the same conditions as the magnetoresistive element 1b before the heat treatment.

The magnetoresistance effect element 1a according to the present invention had a magnetoresistance change rate before the heat treatment of about 5%, whereas the magnetoresistance change rate after the heat treatment was slightly reduced to about 4%. On the other hand, the magnetoresistance effect element 1b of the comparative example had a magnetoresistance change rate of about 4% before the heat treatment, but the heat resistance greatly reduced the magnetoresistance change rate to about 1%. In other words, the magnetoresistive effect element 1a according to the present invention has a stable magnetoresistance change rate with respect to heat treatment, assures quality, and
Even in applications involving heat, it is possible to prevent the magnetoresistance ratio from decreasing by forming the separation film 3 from W or a W alloy.

FIG. 9 is a sectional view of a magnetoresistive element 1 according to a second embodiment of the present invention.

In FIG. 9, a separation film (nonmagnetic conductive film) 3 of an alloy (W—Co or W—Ag) containing W as a main component is formed on the upper surface of a substrate 6, and a Ni—Fe alloy is formed on the upper surface thereof. (N
(i is 82 at%). Further, an antiferromagnetic film 4 of Fe-Mn or the like, a W alloy separation film 3, and a ferromagnetic film 2 of Ni-Fe alloy or the like are sequentially formed on the upper surface. It is possible to form the magnetoresistive element 1 having a laminated structure of two or more laminated layers using the above-described artificial lattice as the laminated unit film 5.

In the case of the magnetoresistive element 1 shown in FIG.
Since the W alloy separation film 3 and the Ni—Fe alloy ferromagnetic film 2 are adjacent to each other, the Ni—Fe alloy ferromagnetic film 2
Can be prevented from deteriorating the soft magnetic characteristic value and decreasing the magnetoresistance change rate.

FIG. 10 is a sectional view of a magnetoresistive element 1 according to a third embodiment of the present invention.

In FIG. 10, an isolation film (non-magnetic conductive film) 3 of an alloy (W—Mo or W—Cr) containing W as a main component is formed on a substrate 6. Then, a ferromagnetic film 2 of a Ni—Co alloy, a separation film 3 of a W alloy, and a ferromagnetic film 2 of a Ni—Co alloy are sequentially formed on the upper surface.

The magnetoresistive element 1 can also have a laminated structure of two or more laminated layers using the above-described artificial lattice as the laminated unit film 5.

Since the magnetoresistive element 1 also has a structure in which the ferromagnetic film 2 of the Ni—Co alloy and the separation film 3 of the W alloy are adjacent to each other, the separation film 3 made of the W alloy
This prevents diffusion at the lamination interface with Fe, and maintains the soft magnetic characteristics of the Ni—Co alloy to guarantee a high rate of magnetoresistance change.

FIG. 11 is a sectional view of a magnetoresistive element 1 according to a fourth embodiment of the present invention.

In FIG. 11, on the upper surface of the substrate 6, a simple lamination type in which a W separation film (non-magnetic conductive film) 3 and a Ni—Fe—Co alloy ferromagnetic film 2 are laminated is formed. This simple lamination type may have a lamination structure of two or more laminations as the lamination unit film 5.

This magnetoresistive element 1 is also made of Ni—Fe—
Since the Co alloy ferromagnetic film 2 and the W separation film 3 are formed in the adjacent laminated unit film 5, the ferromagnetic film Ni—Fe
It is possible to prevent deterioration of the soft magnetic characteristics of the -Co alloy and effectively prevent the rate of change in magnetoresistance from decreasing.

Now, how the magnetoresistance effect occurs in the magnetoresistance effect element 1 of the fourth embodiment will be examined.

FIG. 12 is a cross-sectional view of the magnetoresistive element 1 in which the simple lamination type of FIG. 11 has a two-layer structure. In this magnetoresistive element 1, when no external magnetic field is applied, antiferromagnetic coupling acts between the ferromagnetic films 2 and 2 to bring the magnetization (arrows in the drawing) into an antiparallel (180 °) state. I have. By the way, assuming that the conduction electrons have spins parallel or antiparallel to the magnetization direction, when the conduction electrons try to enter the ferromagnetic film 2, the electrons having spins in the same direction as the magnetization are free to enter the ferromagnetic film 2. However, if the spin direction is reversed, it is scattered near the interface (spin-dependent scattering).

Therefore, when the magnetization between the ferromagnetic films 2 and 2 is in an antiparallel state (a state in which the magnetization of each ferromagnetic film is in the opposite direction every other layer), electrons having spins in either direction have a spinning direction. The electric resistance is maximized because the light is scattered at the interface of the ferromagnetic film having the magnetization in the opposite direction to that of the ferromagnetic film.

On the other hand, as shown in FIG. 13, when a sufficiently strong external magnetic field is applied to the magnetoresistive film to make the magnetization between the ferromagnetic films 2 and 2 parallel, conduction electrons having spins in the same direction as the magnetization are obtained. Move without being scattered. Electrons having opposite spins are scattered, but the electric resistance is minimized as a whole.

Next, a method of manufacturing the magnetoresistive element 1 of the present invention will be briefly described.

FIG. 14 is a sectional view of a sputtering apparatus for forming the magnetoresistance effect element 1 of the present invention. 14, the sputtering apparatus 30 has a bipolar cold cathode glow discharge tube structure including a pair of cathodes 31 and anodes 32 at the top and bottom. The cathode corresponds to a target, and the anode is configured to also serve as a substrate holder.

Then, a gas is introduced into the vacuum chamber 33 from the gas inlet 34, and a current and a voltage of several KV are applied between the two electrodes while maintaining an argon atmosphere of, for example, 1 × 10 ⁻¹ Torr. Occurs. This glow discharge forms argon plasma in the discharge space. The argon positive ions in the plasma are accelerated by the cathode potential drop near the cathode 31, collide with the target cathode surface, and sputter vaporize the target surface. The sputtered particles are deposited on a substrate placed on the anode to form each film.
The inside of the vacuum chamber 33 is evacuated by a vacuum pump 35.

With the sputtering apparatus 30 as described above, the laminated unit film 5 including at least the separation film 3 and the ferromagnetic film 2 is formed on the substrate 6 in a single lamination or a plurality of laminations.
The magnetoresistive element 1 is subjected to a vacuum heat treatment in a later step by a sputtering method. Since this heat treatment can be performed by a known technique, the details are omitted, but the heat treatment is performed in a vacuum (for example, about 10 ⁻² Torr) at a temperature of 300 to 450 ° C. for 30 minutes to 3 hours. At this time, if the separation film 3 is a Cu alloy, the magnetic resistance and the like decrease,
This will adversely affect quality.

FIGS. 15 and 16 are sectional views of a magnetoresistive element 1 according to another embodiment of the present invention.

The magnetoresistive element 1 of FIG. 15 has a first upper electrode film 7a and a second upper electrode film 7b on both sides on the upper surface of the uppermost layer of the artificial lattice layer formed by the sputtering apparatus 30 of FIG. Is formed.

In the magnetoresistive element 1 shown in FIG. 16, the upper electrode film 8a is formed on the upper surface of the uppermost layer of the artificial lattice layer formed by the above-described method, and the lower electrode is formed on the lower surface of the lowermost layer of the artificial lattice layer. The electrode film 8b is formed. Thus, the magnetoresistance effect element 1 is manufactured. Note that the electrode film does not have to be on the entire surface of the magnetoresistive element 1.

FIG. 17 is a perspective view of a main part of a magnetic sensor 20 in which the magnetoresistive element 1 of the present invention is mounted on a flat ignition device of an internal combustion engine.

In FIG. 17, a gear 22 having a tooth profile 21 on its outer peripheral surface is fitted around one end of a rotating shaft (not shown) connected to the ignition device. The magnetoresistive element 1 is arranged to face the gear 22.

This magnetoresistive element 1 is arranged parallel to the end face 25 of the bias magnet 15. And
The center of the magnetoresistive element 1 is provided at a position slightly displaced in the radial direction from the center axis of the magnet 15. This is to utilize the divergence of the magnetic field of the cylindrical magnet magnetized in the axial direction.

The gear 22 has the same structure as that shown in FIG. And the magnetic flux coming out of the magnet is gear 2
2, the magnetic field angle θ applied to the magnetoresistive element 1 changes in a waveform each time the gear 22 passes through the tooth form 21 of the gear 22 and the concave part 23 between the gears 22 as the gear 22 rotates. It changes by one cycle. Since the deflection angle can be about 20 degrees at the maximum, it is suitable for obtaining a large resistance change.

Since the magnetoresistive element 1 can be arranged parallel to the gear 22, the magnetoresistive effect can be made to be advantageous even in an environment involving heat. Moreover, the magnetoresistive element 1 has heat resistance performance,
The rate of change in magnetoresistance is not reduced by heat.
As a result, a magnetic sensor having excellent heat resistance can be expected.

FIG. 18 is a sectional view of a main part provided in a fuel injection control device of another embodiment using the magnetoresistive element 1 of the present invention as a magnetic sensor 20.

In FIG. 18, in the engine electronic control (not shown), the required fuel amount is determined from the intake air amount and the number of revolutions to control the injection nozzle. Requires heat resistance performance of ° C.

Then, the magnetoresistive element 1 of the present invention
The mounting configuration is as follows. The magnetoresistive element 1 is arranged perpendicular to the end face 16 of the magnet 15. Further, the deflection angle of the magnetic field is kept at about 20 degrees at the maximum. Further, the diameter of the gear 22 is 85 mm, the height of the tooth profile 21 formed on the outer periphery thereof is 2 mm, and the length is 2.5 mm. Further, the length of the concave portion 23 between the tooth shapes 21 is 2 mm, and all the teeth are formed at 48. Further, the magnet 15 is provided near the magnetoresistive element 1 so that the magnetoresistive change rate of the magnetoresistive element 1 is sufficiently saturated and the magnetoresistive change rate of the magnetoresistive element 1 is sufficiently saturated. It is configured to be 200 gauss or more.

The magnetoresistive element 1 according to the present invention has a high magnetoresistance change rate without causing waveform distortion with respect to the period of the magnetic field deflection angle. In addition, it is possible to cope with such heat and gas resistance without reducing the magnetoresistance ratio.

FIG. 19 is a sectional view of a turbine angle difference detecting position sensor according to another embodiment in which the magnetoresistive element 1 according to the present invention is used as a magnetic sensor 20.

Also in this case, as a use condition of the magnetoresistive effect element 1, it is necessary to obtain an output signal having good linearity with respect to displacement and to assure a magnetoresistance change rate with respect to temperature.

The configuration of the magnetic sensor 20 shown in FIG.
The magnetic sensor 20 of the present embodiment has substantially the same configuration except that the tooth profile 21 of the gear 22 is formed in a plane. Further, the magnetic sensor 20 according to the present invention can cope with heat resistance and weather resistance without lowering the rate of change in magnetoresistance. Further, it is possible to extract a signal excellent in linearity in a non-contact state. Further, the temperature coefficient of the magnetoresistive element 1 is greatly changed depending on the magnitude of the magnetic field received from the magnet 22, but it is recognized that the magnetoresistive element 1 also exhibits excellent performance in this respect.

[0073]

The magnetoresistance effect element of the present invention has a magnetoresistance change ratio by laminating a W or W alloy separation film (nonmagnetic conductive film) adjacent to a ferromagnetic film of an alloy containing Ni as a main component. Can be improved. At the same time, the separation film of W or W alloy can also prevent the soft magnetic properties of the ferromagnetic film containing Ni as a main component from deteriorating and the rate of change in magnetoresistance from decreasing.

Further, the decrease in the magnetoresistance ratio of the artificial lattice film of the magnetoresistance effect film due to heating in the heat treatment step in the manufacturing process can be prevented by the interposition of the W or W alloy separation film, and the quality is stabilized. A magnetoresistive element can be produced.

It is expected that the corrosion resistance can be improved by adjoining a W or W alloy separation film to a ferromagnetic film of an alloy containing Ni as a main component.

Further, by using the magnetoresistive element for a magnetic sensor or the like, it is expected that high sensitivity can be maintained without reducing the magnetoresistance change rate even under a condition involving heat.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a magnetoresistive element according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a method of measuring a magnetoresistive element according to the present invention.

FIG. 3 is a hysteresis characteristic diagram showing a relationship between an external magnetic field (H) and a magnetization (M) before heat treatment of a magnetoresistive element according to the present invention.

FIG. 4 is a hysteresis characteristic diagram showing a relationship between an external magnetic field (H) and a magnetoresistance change rate of a magnetoresistance effect element according to the present invention before heat treatment.

FIG. 5 is a history characteristic diagram of a comparative example with respect to FIG. 3;

FIG. 6 is a history characteristic diagram of a comparative example with respect to FIG. 4;

FIG. 7 is a hysteresis diagram showing a relationship between an external magnetic field (H) and a magnetoresistance ratio of a magnetoresistance effect element according to the present invention after heat treatment.

8 is a hysteresis characteristic diagram showing a relationship between a magnetic field (H) and a rate of change in magnetoresistance in a comparative example with respect to FIG. 7;

FIG. 9 is a sectional view of a magnetoresistive element according to a second embodiment of the invention.

FIG. 10 is a sectional view of a magnetoresistive element according to a third embodiment of the present invention.

FIG. 11 is a sectional view of a magnetoresistive element according to a fourth embodiment of the present invention.

FIG. 12 is an explanatory diagram of a change state of the magnetoresistance in FIG. 11;

13 is an explanatory diagram of the magnetoresistance change state of FIG.

FIG. 14 is a schematic view of a sputtering apparatus for manufacturing a magnetoresistive element of the present invention.

FIG. 15 is a cross-sectional view of a magnetoresistive element in which an electrode according to one embodiment of the present invention is manufactured.

FIG. 16 is a sectional view of a magnetoresistive element in which an electrode according to another embodiment of the present invention is manufactured.

FIG. 17 is a cross-sectional view of a main part of a magnetic sensor according to an embodiment provided with a magnetoresistive element according to the present invention.

FIG. 18 is a sectional view of a main part of a magnetic sensor according to another embodiment provided with a magnetoresistive element according to the present invention.

FIG. 19 is a cross-sectional view of a main part of a magnetic sensor according to still another embodiment having the magnetoresistive element according to the present invention.

FIG. 20 is a sectional view of a conventional magnetoresistance effect element.

FIG. 21 is a conceptual diagram of a conventional magnetic sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnetoresistance effect element 2 ... Ferromagnetic film 3 ... Separation film 4 ... Antiferromagnetic film 5 ... Laminated unit film 6 ... Substrate 7a ... First upper electrode film 7b ... Second upper electrode film 8a ... Upper electrode film 8b ... Lower electrode film 10 ... Pin 15 ... Magnet 16 ... End face 20 ... Magnetic sensor 21 ... Tooth shape 22 ... Gear 23 ... Recess 30 ... Sputtering device 31 ... Cathode 32 ... Anode 33 ... Vacuum tank 34 ... Gas introduction hole 35 ... Vacuum pump Reference Signs List 50 ... Magnetoresistance effect element 51 ... Magnetic film 52 ... Separation film 53 ... Substrate 61 ... Shaft 62 ... Rotor gear 63 ... Small teeth 64 ... Bias magnet 65 ... Yoke 66 ... Detection coil

Claims (9)

[Claims] An artificial lattice laminated unit film (5) including at least a ferromagnetic film (2) of an alloy containing Ni and a separation film (3) disposed adjacent to said ferromagnetic film (2). Has,
The magnetoresistance effect element, wherein the separation film (3) included in the laminated unit film (5) is made of W or an alloy containing W. 2. A magnetoresistive element according to claim 1, wherein said ferromagnetic film is made of a Ni—Fe alloy. 3. The laminated unit film (5) is an antiferromagnetic film (4).
And the ferromagnetic film (2), the separation film (3), and the ferromagnetic film (2) are laminated.
2. The magnetoresistance effect element according to claim 1, wherein the magnetoresistance effect element is made of an alloy containing i as a main component. 4. The magnetoresistive element according to claim 3, wherein said ferromagnetic film (2) is made of a Ni—Fe alloy and said separation film (3) is made of W. 5. The antiferromagnetic film (4) is composed of α-Fe ₂ O ₃ ,
The magnetoresistive element according to claim 3, wherein the element is NiO, an Fe—Mn alloy, or a PtMn alloy. 6. The antiferromagnetic film (4) contains at least one element selected from the group consisting of Ru, Zr, Nb, Ge, V, Co, Hf, Pt and Pd in an Fe-Mn alloy. 5. The magnetoresistive element according to claim 3, wherein: 7. The separation unit (3) wherein the laminated unit film (5) is the separation film (3).
And an artificial lattice in which the ferromagnetic film (2), the separation film (3), and the ferromagnetic film (2) are laminated, wherein the ferromagnetic film (2) is an alloy containing Ni, and 2. The film according to claim 1, wherein the film is an alloy containing W.
3. The magnetoresistive effect element according to item 1. 8. The separation membrane (3) wherein the laminated unit membrane (5) is the separation membrane (3).
The ferromagnetic film (2), the ferromagnetic film (2), the antiferromagnetic film (4), the separation film (3), and the ferromagnetic film (2). The magnetoresistive element according to claim 1, wherein is an alloy containing Ni and the separation film (3) is an alloy containing W as a main component. 9. An artificial lattice in which a ferromagnetic film (2) of an alloy containing Ni and a separation film (3) of W or an alloy containing W as a main component adjacent to the ferromagnetic film (2) are laminated. A magnetic sensor, wherein the magnetoresistive element (1) is provided with a bias magnet (15).