JPH0949059A - Material having magnetic resistance effect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material having magnetic resistance effect in which magnetic resistance effect more excellent than that of a permalloy thin film can be obtd. by a single layer film. SOLUTION: This material is the one having a body-centered cubic structure, in which fine crystal grains with <=5nm average grain size essentially consisting of Fe are dispersed into amorphous phases contg. compounds of at least one or >= two kinds selected from the groups of rare earth metal elements, Ti, Zr, Hf, V, Nb, Ta and W and N or O, the volume ratio of the amorphous phases is regulated to the one occupying at least >=20% of the structure, furthermore, the specific resistance of the amorphous phases is regulated to >=10<2> μΩm, and the distance between the fine crystal grains is regulated to 3 to 10nm on the average.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for a magnetoresistive effect element which is applied to a magnetic sensor, a magnetic head and the like.

[0002]

2. Description of the Related Art Conventionally, materials whose resistance changes in the direction of current when a magnetic field is applied to a conductive material are generally called magnetoresistive materials, and materials of this kind have been put into practical use.
There are Ni-Fe alloy thin films (permalloy thin films) and Co-Ni alloy thin films. In addition, the amount of change in magnetic resistance (Δρ) obtained with these alloy thin films is generally 0.007 μΩcm, and it can be applied and developed as a magnetic sensor such as a position sensor or a rotation sensor, or as a reproducing head of a magnetic head. It is being advanced. Therefore, in the future, it is required to develop a material exhibiting a larger magnetoresistive effect in response to the higher resolution of the magnetic sensor or the narrower track of the magnetic head.

[0003]

However, with the amount of change in magnetoresistance obtained by the Ni-Fe alloy thin film or the Co-Ni alloy thin film as described above, it is expected that the resolution of the magnetic sensor will be improved in the future. When applied to a magnetic head, there is a problem that the high density of magnetic recording cannot be sufficiently dealt with, and development of a material exhibiting a higher magnetoresistance change amount is desired. Based on these technical backgrounds, the inventors of the present invention have arrived at the present invention as a result of research on a material exhibiting an excellent magnetoresistive effect among magnetic materials of other compositions.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetoresistive effect material capable of obtaining an excellent magnetoresistive effect equivalent to or higher than that of a permalloy thin film in a single layer film. .

[0005]

In order to solve the above-mentioned problems, in order to solve the above-mentioned problems, fine crystal grains having a body-centered cubic structure containing Fe as a main component and having an average crystal grain size of 5 nm or less are rare earth metal elements and A dispersion in an amorphous phase containing a compound of at least one or two or more elements M and N or O selected from the group of Ti, Zr, Hf, V, Nb, Ta and W, and Amorphous phase has a volume ratio of at least 2 of texture
The specific resistance of the amorphous phase is 10 ² μΩm or more, and the distance between the fine crystal grains is 3 to 10 nm on average. .

In order to solve the above-mentioned problems, the invention according to claim 2 is such that the composition according to claim 1 is represented by the following composition formula. Fe _a M _b N _c , where the composition ratio a, b, c in this composition formula is 60% a ≦ 60%
70, 10 ≦ b ≦ 15, and 19 ≦ c ≦ 25 are satisfied. In order to solve the above-mentioned problems, the invention according to claim 3 is such that the composition according to claim 1 is represented by the following composition formula. Fe _d M _e O _f, however, the composition ratio d, e, f is the atomic%, 40 ≦ d ≦ 50,10 ≦
It is assumed that the relationship of e ≦ 30 and 20 ≦ f ≦ 40 is satisfied.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the magnetoresistive effect material according to the present invention, fine crystal grains having a body-centered cubic structure as a main component and having an average crystal grain size of 5 nm or less and rare earth metal elements and Ti, Zr, Hf, V, and N are used.
b, Ta, W dispersed in an amorphous phase containing a compound of at least one or two or more elements M and N or O selected from the group consisting of b, Ta, and W, and the amorphous phase in a volume ratio. A ratio that occupies at least 20% or more of the structure, a resistivity of the amorphous phase is 10 ² μΩm or more, and a distance between the fine crystal grains is 3 to 10 nm on average. Is.

When the above structure is used in the present invention, the composition is preferably represented by the following composition formula. Fe _a M _b N _c However, the composition ratio a, b, c in this composition formula is
It is assumed that the relations of 60 ≦ a ≦ 70, 10 ≦ b ≦ 15, 19 ≦ c ≦ 25 are satisfied. In the above Fe-M-N composition system, specifically, FeTiN, FeZrN, FeHf
N, FeVN, FeNbN, FeTaN, FeWN composition system, or as the element M, Ti, Zr, Hf,
You may use 2 or more types selected from the group of V, Nb, Ta, and W. In the above composition, the Fe content is 60 to 7
The content of 0 atom%, the content of the element M is 10 to 15 atom%, and the content of N is 19 to 25 atom%. ,
This is because iron nitride tends to precipitate. Further, within these ranges, a high Δρ is easily obtained.

Next, when the above structure is used in the present invention, the composition is preferably represented by the following composition formulas. Fe _{d Me} O _f However, the composition ratio d, e, f in this composition formula is atomic%
Then, the relations 40 ≦ d ≦ 50, 10 ≦ e ≦ 30, and 20 ≦ f ≦ 40 are satisfied. In the above FeMO composition system, specifically, FeTiO, FeZrO, FeHf
O, FeVO, FeNbO, FeTaO, FeWO composition system, or as element M, Ti, Zr, Hf,
You may use 2 or more types selected from the group of V, Nb, Ta, and W. In the above composition, the Fe content is 40 to 7
0 atom%, the content of element M is 5 to 30 atom%, and the content of N is 10 to 40 atom%. It becomes easy to enter into a phase state. Further, within these ranges, high Δρ is easily obtained by spin-dependent tunneling of conduction electrons through an amorphous phase having a high specific resistance.

The magnetoresistive material according to the present invention can be obtained as a magnetoresistive material film using a general-purpose technique, for example, a thin film forming apparatus such as sputtering or vapor deposition. Also,
As the film forming device, a high frequency bipolar sputtering device, a DC sputtering device, a magnetron sputtering device, a tripolar sputtering device, an ion beam sputtering device, a facing target type sputtering device and the like can be used. Further, as a sputter gate, Fe
Ti, Zr, Hf, V, Nb, Ta, on the target
A composite target in which pellets of W or the like are arranged can be used. As a method of adding O or N into the film, reactive sputtering is effective in which sputtering is performed in an Ar + O ₂ or Ar + N ₂ mixed atmosphere gas in which an oxygen gas or a nitrogen gas is mixed in an inert gas such as Ar. . In addition, a composite target in which Fe, element M, or an oxide or nitride thereof is arranged on Fe, FeM, or FeM-based alloy target is used.
It can also be produced in an inert gas such as r.

FIG. 1 shows an example of the structure of this type of thin film forming apparatus. The apparatus of this example has a decompression container 3 configured to have an exhaust hole 1 at the bottom and an atmosphere gas supply hole 2 at the side so as to be evacuated, and a substrate holder (not shown) inside the decompression container 3. It is mainly composed of a supported substrate 4 and a target 5 arranged to face the substrate 4. Further, the target 5 is configured to include a target body 5a made of Fe, which is the basic composition of the magnetoresistive effect material of the present invention, and a plurality of chips 5b of elements corresponding to the additive component elements. Using the apparatus shown in FIG. 1, the inside of the decompression container 2 is decompressed by exhausting the air inside the decompression container 2 from the exhaust hole 1, and the Ar gas, Ar gas and Ar gas are supplied from the gas supply hole 2 according to the target composition. Gas + N ₂ gas or Ar gas + O ₂ gas is supplied to perform sputtering, particles are blown from the target 5 and deposited on the surface of the substrate 4, and a magnetoresistive material film 7 having a desired composition can be obtained. .

Magnetoresistive material film 7 obtained as described above
2 has a structure in which a large number of fine crystal grains 7b mainly composed of bccFe are deposited inside the matrix of the amorphous phase 7a, as shown in FIG. Therefore, the magnetoresistive effect material film 7 shown in FIG. 2 has a structure in which a large number of fine crystal grains 7b of ferromagnetic metal are dispersed inside the amorphous phase 7a containing a large amount of the element M or O or N.

Further, the magnetoresistive material film 7 is formed into 200
It is also possible to heat-treat at a temperature of up to 500 ° C. to further precipitate fine crystal grains 7b from the amorphous phase 7a. At that time, it is preferable to perform heat treatment in a static magnetic field. Therefore, it can be presumed that a structure in which the amorphous phase 7a and the fine crystal grains 7b are in a mixed phase is preferable, and in that case, the amorphous phase 7a
a is required to be 20% or more by volume ratio, more preferably 50
It seems that more than% is necessary.

In this structure, fine crystal grains 7b
Is preferably 5 nm or less, and the mutual distance between a large number of dispersed fine crystal grains 7b is 3 to 3 on average.
It is preferably 10 nm. These fine crystal grains 7b
If the distance between them is smaller than 3 nm on average, there is a strong tendency for the current to flow normally, and if it is larger than 10 nm, it becomes difficult for the tunnel current to flow and an excellent MR effect cannot be obtained, which is not preferable. As described above, the amorphous phase has fine crystal grains of Fe having a crystal grain size of 5 nm or less, an interval between the fine crystal grains is 3 to 10 nm, and a high specific resistance of 10 ² μΩm or more. In the case of the magnetoresistive effect material film 7, since the conductive fine crystal grains 7b of bccFe are dispersed in the amorphous phase 7a having a high specific resistance through a suitable distance, the spin directions of the adjacent fine crystal grains are A current flows due to the tunneling effect of conduction electrons depending on, and a high MR effect can be obtained.

In this type of amorphous phase 7a, bccF is added.
In the magnetoresistive effect material film 7 having the structure in which the fine crystal grains 7b of e are deposited, the electric resistance of the fine crystal grains 7b is much smaller than the specific resistance of the amorphous phase. The specific resistance of the film 7 can be regarded as the specific resistance of the amorphous phase 7a. In addition, the magnetoresistive effect material film 7 is applied in a static magnetic field 2
In the case of heat treatment at 00 to 500 ° C., the rate of change in magnetoresistance per unit magnetic field is large. The magnetoresistive material film 7 configured as described above causes a large resistance change (Δρ) in response to application of a magnetic field, and thus can be applied to a magnetic field sensor, a magnetic head, and the like.

[0016]

EXAMPLES Examples of the present invention will be described below with reference to the drawings, but it goes without saying that the present invention is not limited to the following examples. Using a high-frequency magnetron sputtering device, using an Fe-Hf-based alloy target as appropriate, Ar +
Film formation was carried out in an O ₂ (0.1 to 2.0%) gas atmosphere to obtain a magnetoresistive material film. The main sputtering conditions are shown below. Preliminary exhaust 1 × 10 ⁻⁵ Pa or less High frequency power 400 W Ar gas pressure 0.8 to 1.0 Pa Substrate Glass substrate (indirect water cooling) Distance between electrodes 40 to 70 mm

The composition of each magnetoresistive material film was determined by inductively coupled plasma (ICP) emission spectrometry and X-ray microanalyzer (EPMA). The sample has a width of 4.5 to 5.0 mm and a length of 22.5 to 24 m.
m and the thickness was about 1 to 2 μm. Once these samples were obtained, the MR characteristics of each sample were measured using an MR tester.

FIG. 3 (a) shows the magnetoresistance change (ρ-H curve) at room temperature in the as-deposited state (as-deposited state) of the comparative sample having the composition Fe ₈₈ Hf ₂ O ₁₀ . Three
FIG. 3B shows a change in magnetoresistance of a comparative sample having a composition of Fe ₅₅ Hf ₁₁ O _{34 in} the as-deposited state, and FIG.
₄ shows changes in magnetoresistance at room temperature in the as-deposited state of a sample of the present invention having a composition of ₄₄ Hf ₂₀ O ₃₆ . FIG. 3 (a)
In (c), the curve connecting the circles shown in (II) is the measured value when the current and the external magnetic field are parallel, and shown in (L).
The curve connecting the marks shows the measured values when the current and the external magnetic field are perpendicular. The comparative samples shown in FIGS. 3 (a) and 3 (b) have different tendencies of change in magnetoresistance with respect to the magnetic field in the cases of II and L, and the anisotropic magnetoresistive effect (see AMR) has been obtained. FIG.
In the sample of the present invention shown in (c), the resistance decreased with respect to the magnetic field in both cases of II and L, and Δρ was 56.6 μm.
4% giant magnetoresistive effect (GMR) in Ωm and Δρ / ρ ₀
It can be seen that is obtained.

Next, FIG. 4A shows a change in magnetoresistance at room temperature of the magnetoresistive material film after heat treatment in a static magnetic field (UFA) of a comparative sample having a composition of Fe ₅₅ Hf ₁₁ O ₃₄ . (B) shows the magnetoresistance change at room temperature of the magnetoresistive material film after the static magnetic field heat treatment (UFA) for the sample of the present invention having the composition of Fe ₄₄ Hf ₂₀ O ₃₆ . The comparative sample shown in FIG. 4A has different tendencies of change in magnetoresistance with respect to the magnetic field in the cases of II and L, and the anisotropic magnetoresistive effect (AMR) found in ordinary magnetic metal is obtained. There is. FIG.
In the sample of the present invention shown in (b), Δρ is 30 μΩm, Δρ /
Although ρ ₀ is about 3%, the change is steeper than in the as-deposited state.

Further, such a steep MR change can be obtained even at a low temperature. FIG. 5A shows the state of the as-deposited film of the sample of the present invention having the composition of Fe ₄₄ Hf ₂₀ O _36.
5B shows the relationship between the specific resistance at K and FIG. 5B shows the relationship between the externally applied magnetic field and the magnetization of the same sample at room temperature and 77K. From this figure, it can be seen that the change in magnetization in response to the change in the external magnetic field is steeper at 77K than at room temperature, and accordingly, the change in resistivity is also steep.

FIG. 6 shows the specific resistance (ρ in the FeHfO system).
₀ / μΩm) and the composition diagram showing the relationship between the composition and FIG.
FIG. 6 is a triangular composition diagram showing the relationship between the resistance change amount (Δρ / μΩm) and the composition in the eHfO system. From these triangular composition diagrams, in order to obtain a high specific resistance of 10 ² ρ ₀ / μΩm or more, 40 ≦ Fe ≦ 50, 10 ≦ Hf ≦ 30, 20 ≦ O ≦
It is clear that it is preferable to satisfy the relationship of 40. Even within this range, 40 ≦ Fe ≦ 50, 15 ≦
It is more preferable to satisfy the relationships of Hf ≦ 25 and 25 ≦ O ≦ 40.

FIG. 8 shows a copy of a high resolution TEM (transmission electron microscope) image of the texture of the sample of the present invention having the composition of Fe ₄₄ Hf ₂₀ O ₃₆ , and FIG. 9 shows the composition of Fe ₅₅ Hf ₁₁ O ₃₄ . The figure which imitated the high resolution TEM (transmission electron microscope) image of the structure | tissue of a comparative example sample is shown. The amorphous grains in each figure are fine crystal grains composed mainly of Fe having a bcc structure. FIG.
As is clear from a comparison between the structures shown in FIG. 9 and FIG. 9, the sample according to the present invention has a fine grain size of 5 nm or less, whereas the comparative sample has a grain size of more than 5 nm. It turned out to be many.

Next, FIG. 1 shows the results of composition analysis by nanobeams (electron beam diameter of 1 nm or less) EXD (energy dispersive X-ray analyzer) of the fine crystal grain portions indicated by the reference numeral in FIG.
No. 0, the electron beam diffraction image of the nanobeam (electron beam diameter is 1 nm or less) of the same portion is shown in FIG. 11, and the composition analysis result by the nanobeam EXD of the amorphous phase portion shown in FIG. 8 is shown in FIG. 13 shows a nanobeam electron diffraction image of the same portion. From the comparison of these figures, a diffraction image peculiar to the crystal structure was obtained in the portion of the fine crystal grains shown in FIG. 8, and compared with the fact that the content of Fe is large, the amorphous phase of In the portion, a diffraction image peculiar to amorphous is obtained, the Fe content is smaller than in the portion, and Hf and O
Is increasing. Therefore, it was revealed that the amorphous phase portion contained a large amount of Hf of the element M and O.

As described above, the magnetoresistive effect of the Fe-Hf-O film was measured. The current permalloy (Δρ =
Compared to 0.7 μΩcm), Δρ is Fe-Hf-
Much larger value for O film (Δρ = 5660μΩcm)
was gotten.

[0025]

As described above, according to the present invention, fine crystal grains having an average crystal grain size of 5 nm or less containing Fe as a main body and having a body-centered cubic structure as a main component are provided with rare earth metal elements and Ti, Zr, Hf,
It has a structure in which it is dispersed in an amorphous phase containing a compound of at least one element or two or more elements M and N or O selected from the group of V, Nb, Ta and W, and has a fine crystal grain structure. The interval is 3 to 5 nm and the resistivity of the amorphous phase is 10 ² μΩm
As described above, due to the giant magnetoresistive effect due to the spin-dependent tunneling of conduction electrons through the amorphous phase having a specific resistance of 10 ² μΩm or more, a high resistance change amount (Δ
ρ) can be obtained.

Next, in the composition system Fe _a M _b N _c , the composition ratios a, b and c in atomic% are 60 ≦ a ≦ 70 and 10 ≦ b.
When the relationship of ≦ 15, 19 ≦ c ≦ 25 is satisfied,
It has a structure in which fine crystal grains are precipitated in an amorphous phase, the distance between the fine crystal grains is 3 to 10 nm, the specific resistance is easily 10 ² μΩm or more, and high Δρ can be obtained. .

Next, Fe _d M _e O _f becomes the composition system, a composition ratio d, e, and f in atomic%, 40 ≦ d ≦ 50,10 ≦ e
When the relationship of ≦ 30, 20 ≦ f ≦ 40 is satisfied,
It has a structure in which fine crystal grains are precipitated in an amorphous phase, the distance between the fine crystal grains is 3 to 10 nm, the specific resistance is easily 10 ² μΩm or more, and high Δρ can be obtained. .

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for producing a magnetoresistive material film according to the present invention.

FIG. 2 is a diagram showing a structural example of a magnetoresistive material film of the present invention.

3 (a) is a diagram showing a magnetoresistive change curve of a comparative sample having a composition of Fe ₈₈ Hf ₂ O _{10 in} the as-deposited state, and FIG. 3 (b) is Fe ₅₅ Hf ₁₁ shows a magnetoresistance change curve remains the deposition of the comparative sample of O ₃₄ having a composition,
FIG. 3C is a diagram showing a magnetoresistance change curve of the sample of the present invention having a composition of Fe ₄₄ Hf ₂₀ O _{36 in} the as-deposited state.

FIG. 4 (a) is an F after heat treatment in a static magnetic field (UFA).
FIG. 4B is a diagram showing a magnetoresistance change curve of a magnetoresistive effect material film sample having a composition of e ₅₅ Hf ₁₁ O ₃₄ at room temperature. FIG. 4B shows a composition of Fe ₄₄ Hf ₂₀ O ₃₆ after heat treatment in a static magnetic field (UFA). It is a figure which shows the magnetoresistive change curve at room temperature of a magnetoresistive effect material film sample.

FIG. 5 (a) is a diagram showing a magnetoresistance change curve at 77K of a magnetoresistive effect material film sample having a composition of Fe ₄₄ Hf ₂₀ O ₃₆ , and FIG. 5 (b) is 77K accompanying an external magnetic field of the sample.
It is a figure which shows the state of the magnetization change at room temperature.

FIG. 6 is a triangular composition diagram showing the composition dependence of the structure and the resistance change amount (Δρ ₀ ) in the as-deposited state of the Fe—Hf—O film.

FIG. 7 is a triangular composition diagram showing the composition dependence of the structure and the resistance change amount (Δρ) in the as-deposited state of the Fe—Hf—O film.

FIG. 8 is a diagram showing a high-resolution TEM image of the texture of a sample of the present invention having a composition of Fe ₄₄ Hf ₂₀ O ₃₆ .

FIG. 9 is a diagram showing a high-resolution TEM image of the texture of a comparative sample having a composition of Fe ₅₅ Hf ₁₁ O ₃₄ .

FIG. 10 is a diagram showing a composition analysis result by EXD of a fine crystal grain portion of a structure of a sample of the present invention having a composition of Fe ₄₄ Hf ₂₀ O ₃₆ .

FIG. 11 is a schematic diagram showing an electron diffraction image of a fine crystal grain portion of the structure of the sample of the present invention having a composition of Fe ₄₄ Hf ₂₀ O ₃₆ .

FIG. 12 is a diagram showing the result of composition analysis by EXD of the amorphous phase portion of the structure of the sample of the present invention having the composition of Fe ₄₄ Hf ₂₀ O ₃₆ .

FIG. 13 is a schematic diagram showing an X-ray diffraction image of an amorphous phase portion of the texture of the sample of the present invention having a composition of Fe ₄₄ Hf ₂₀ O ₃₆ .

[Explanation of symbols]

 1 exhaust hole, 2 introduction hole, 3 decompression container, 4 substrate, 5 target, 5a target body, 5b chip, 7 magnetoresistive effect material film, 7a amorphous phase, 7b fine crystal grains.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 20, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3 is a magnetoresistance change curve of a comparative sample having a composition of Fe ₈₈ Hf ₂ O _{10 in} the as-deposited state and Fe ₅₅ H
The magnetic resistance change curve of the sample of the comparative example having the composition f ₁₁ O _{34 in} the as-deposited state and the magnetic resistance change curve of the sample of the present invention having the composition of Fe ₄₄ Hf ₂₀ O _{36 in} the as-deposited state are shown. It is a figure.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5 is a magnetoresistance change curve at 77K of a magnetoresistance effect material film sample having a composition of Fe ₄₄ Hf ₂₀ O ₃₆ ;
It is a figure which shows the state of 77 K and the magnetization change at room temperature with an external magnetic field of the same sample.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Makino 1-7 Yukiya Otsuka-cho, Ota-ku, Tokyo Alps Electric Co., Ltd. (72) Inventor Seiji Mitani No. 41-305, 7-Yagiyama Midoricho, Taihaku-ku, Sendai City, Miyagi Prefecture

Claims (3)

[Claims] 1. Fine crystal grains having an average crystal grain size of 5 nm or less, which is mainly composed of Fe having a body-centered cubic structure, are selected from the group of rare earth metal elements and Ti, Zr, Hf, V, Nb, Ta and W. Which is dispersed in an amorphous phase containing a compound of at least one or two or more elements M and N or O,
The volume ratio of the amorphous phase accounts for at least 20% or more of the structure, and the resistivity of the amorphous phase is 10 ²
A magnetoresistive effect material having a size of μΩm or more and an average distance between the fine crystal grains of 3 to 10 nm. 2. The magnetoresistive effect material according to claim 1, wherein the composition is represented by the following composition formula. Fe _a M _b N _c However, the composition ratio a, b, c in this composition formula is
It is assumed that the relations of 60 ≦ a ≦ 70, 10 ≦ b ≦ 15, 19 ≦ c ≦ 25 are satisfied. 3. The magnetoresistive effect material according to claim 1, wherein the composition is represented by the following composition formula. Fe _{d Me} O _f However, the composition ratio d, e, f is 40% d ≦ 50, 1 in atomic%.
It is assumed that the relationship of 0 ≦ e ≦ 30 and 20 ≦ f ≦ 40 is satisfied.