JPH0883939A - Magnetoresistance element - Google Patents

Abstract

PURPOSE: To obtain a magnetoresistance element which exhibits a larger MR ratio and has a magnetoresistance effect film having high magnetic field sensitivity by providing shape anisotropy in the grains of a ferromagnetic material. CONSTITUTION: A board 1 is coated with a mask film 2, and stripelike grooves 2a are formed on the film 2 by an electron beam lithography method. Then, when a Co-Ag alloy film is deposited by an RF sputtering method, an alloy film 3b is formed on the film 2, and an alloy film 3a is formed in the grooves 2a. Since the Co is solid insoluble in Ag, Co forms grains. Since the grains of the ferromagnetic material has shape anisotropy, the magnetoresistance change rate is increased in the specific magnetic field direction. Accordingly, a magnetic field is applied in such a direction to detect the change of the electric resistance, thereby enhancing the magnetic field sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element (MR element) used for a magnetoresistive effect type head (MR head), a magnetic sensor (MR sensor) and the like.

[0002]

2. Description of the Related Art An MR element is an element for measuring a magnetic field strength and its change by detecting a change in electric resistance of a magnetic film due to application of a magnetic field. Therefore, the MR element is generally required to have a large magnetoresistance change rate (MR ratio). Conventionally, a Fe-Ni (permalloy) alloy is generally used as a magnetic material used for MR elements. However, the Fe-Ni alloy has a very small magnetoresistance change rate of 2 to 3%, and is not sufficiently satisfactory as a magnetic material used for an MR element.

In recent years, a magnetic multilayer film has been proposed in which a non-magnetic thin film is interposed between magnetic thin films. For example, there is known a magnetic multilayer film in which a Cu film is used as a non-magnetic film and a plurality of units are alternately laminated with a Co film as a magnetic thin film. In such a magnetic multilayer film, antiferromagnetic coupling is formed between Co-Co layers, and it is generally called an artificial lattice type.

It is also known that a Cu film is used as the non-magnetic thin film and magnetic films having different coercive forces are provided on both sides of the Cu film, for example, a Co film and an Fe film are provided on both sides to form a sandwich structure. Such a magnetic multilayer film is generally called a spin valve type.

[0005]

However, in recent years,
High density recording of magnetic recording media is desired, and in order to cope with such high density recording, an MR element having a larger MR ratio and high magnetic field sensitivity is desired.

It is an object of the present invention to provide a novel structure of a magnetoresistive film which satisfies such demands and has a larger MR ratio and a high magnetic field sensitivity.

[0007]

A magnetoresistive element according to a first aspect of the present invention comprises a ferromagnetic material and a nonmagnetic material which is in a non-solid solution or eutectic relationship with the ferromagnetic material. The magnetic substance is provided with an alloy film forming grains in the non-magnetic substance layer, and the grains of the ferromagnetic substance are characterized by having shape anisotropy.

That is, that the grains of the magnetic substance have shape anisotropy means that the grains of the ferromagnetic substance are not spherical.
It means having a distorted shape in a specific direction. For example, it may be a flattened shape that spreads in a specific two-dimensional direction, or a rugby ball shape that extends in a specific one-dimensional direction. With respect to such anisotropy, for example, when the shorter diameter is 1, the longer diameter is preferably about 1.3 to 3.

A magnetoresistive element according to a second aspect of the present invention comprises a ferromagnetic material and a nonmagnetic material which is in a non-solid solution or eutectic relationship with the ferromagnetic material. It is characterized in that it has an alloy film which forms grains and the width in one direction of the alloy film is 1 μm or less.

In one of the preferred embodiments according to the second aspect, the alloy film is formed in a stripe shape and the width of the stripe is 1 μm or less. Further, in this embodiment, the width of the alloy film in one direction may be the film thickness. Therefore, the thickness of the alloy film may be 1 μm or less.

In the second aspect, the width of the alloy film in one direction is more preferably 50 nm or less, and most preferably 20 nm or less. In the first aspect and the second aspect of the present invention, the nonmagnetic layer has conductivity and is formed of a metal or an alloy.

The manufacturing method of the present invention is a method capable of manufacturing the magnetoresistive element according to the second aspect of the present invention, in which a mask film having stripe-shaped grooves with a width of 1 μm or less is formed on a substrate. Forming step, forming an alloy film on the substrate in the stripe-shaped groove and on the mask film, and removing the mask film from the substrate so that only the alloy film in the stripe-shaped groove of the mask film is formed on the substrate And a step of forming a striped alloy film.

In the manufacturing method of the present invention, a method of forming a stripe-shaped groove having a width of 1 μm or less on the mask film is performed by patterning by an electron beam lithography method or a photolithography method which is generally adopted in a semiconductor manufacturing process. Can be formed. Further, the stripe-shaped groove can be appropriately set in accordance with the width of the stripe of the finally formed alloy film, and as in the second aspect, the width is more preferably 50 nm or less, Most preferably, it is 20 nm or less.

In the manufacturing method of the present invention, the method of forming the alloy film is not particularly limited, but the alloy film can be formed by, for example, a vacuum vapor deposition method or an RF sputtering method.

For removing the mask film, a method generally used for removing the mask film in the semiconductor manufacturing process can be adopted. In each of the above aspects of the present invention, an alloy film of a ferromagnetic material and a nonmagnetic material that is in a non-solid solution or eutectic relationship with the ferromagnetic material is used as the magnetoresistive film. When Co is used as the ferromagnetic material, this C
Examples of the non-magnetic material having a eutectic relationship with o include Cu. Therefore, a CoCu alloy film can be used.

When Co is used as the ferromagnetic material, C
As the non-magnetic material having a non-solid solution relationship with o, Ag or Pb can be used. Therefore, the CoAg alloy film,
And a CoPb alloy film can be used. V, Cr, or Mn can be added to the Co ferromagnetic material of these alloys.

When the ferromagnetic material is Fe, Ag, Bi, Mg or P is used as a non-solid-solution magnetic material with the ferromagnetic material.
b or the like can be used. Therefore, the FeAg alloy film, the FeBi alloy film, the FeMg alloy film, and the FePb alloy film can be used. Co, Ni, Cu, or Zn can be further added to the ferromagnetic material of Fe of these alloys.

When Ni is used as the ferromagnetic material, N
Ag can be used as a non-magnetic material having a non-solid solution relationship with i. Therefore, the NiAg alloy film can be used. Further, V, Cr, or Mn can be added to the ferromagnetic body made of Ni of these alloy films.

These alloy films can be formed as an alloy film in which a ferromagnetic substance forms grains in a non-magnetic substance by forming a thin film by vacuum vapor deposition, RF sputtering or the like.

[0020]

According to the first aspect of the present invention, the ferromagnetic substance forms grains in the non-magnetic substance of the alloy film, and the grains of the ferromagnetic substance have shape anisotropy. In such an alloy film containing dispersed ferromagnetic grains, the magnetization state of the grains changes from a random arrangement to a ferromagnetic arrangement as the applied magnetic field increases, and surrounds the grains of the ferromagnetic material. In a non-magnetic matrix, the scattering state of conduction electrons largely changes depending on the magnetization state of grains. As a result, the magnetoresistive change rate of the alloy film becomes large. In such an alloy film containing grains of a ferromagnetic substance, since the grains of the ferromagnetic substance have shape anisotropy, the magnetoresistance change rate is further increased in a specific magnetic field direction. Therefore, the magnetic field sensitivity can be further increased by applying a magnetic field in such a direction and detecting a change in electric resistance.

In the second aspect of the present invention, the width of the alloy film in one direction is 1 μm or less. The inventors have found that by forming the alloy film so as to have a narrow width of 1 μm, the magnetoresistance change rate of the alloy film increases in a specific direction. By forming the alloy film to have such a narrow width, it is presumed that when grains are formed in the alloy film, grains having shape anisotropy are formed. In the magnetoresistive element of the second aspect, the rate of change in magnetoresistance increases in a specific direction. Therefore, magnetic field sensitivity can be increased by applying a magnetic field in this direction and measuring the change in electrical resistance.

According to the manufacturing method of the present invention, the magnetoresistive element according to the second aspect of the present invention can be manufactured in a simple process and with an alloy film having a desired width.

[0023]

EXAMPLE 1 FIG. 1 is a schematic sectional view showing a manufacturing process of an example according to the present invention. Referring to FIG. 1A, a mask film 2 (having a film thickness of 1 μm) made of a resist material or the like is formed on a substrate 1 such as glass.
m) is applied. Next, referring to FIG. 1B, a stripe-shaped groove 2a is formed in the mask film 2 by an electron beam lithography method. In this embodiment, the stripe-shaped groove 2a
Is set to 5000 Å (0.5 μm), and the width of the stripe-shaped mask film is also set to 5000 Å.

Next, referring to FIG. 1C, a CoAg alloy film was deposited by RF sputtering. An alloy film 3b is formed on the mask film 2, and an alloy film 3a is formed in the stripe-shaped groove 2a of the mask film 2. Alloy film 3
The film thicknesses of a and 3b were formed to be 500 Å.

Next, referring to FIG. 1D, the mask film 2
Was lifted off to leave only the alloy film 3a in the stripe-shaped groove 2a of the mask film 2 on the substrate 1. As a result, the striped alloy film 3a having a width of 5000 Å becomes
It was formed on the substrate 1.

FIG. 2 shows a state in which Cu electrodes 4 and 5 (thickness 1000Å) are formed on both ends of the striped alloy film 3a obtained as described above. In the CoAg alloy films of the above examples, Co is 20 atom%,
Ag is set to 80 atom%.

Since Co has a non-solid solution relationship with Ag, Co forms grains in the CoAg alloy film. Further, since the CoAg alloy film is formed in the groove of the mask film having a very narrow width, the grains formed in such a groove have a flat shape that spreads in the stripe-shaped extending direction, Alternatively, it is assumed to have a rugby ball shape.

The MR ratio and operating magnetic field of the magnetoresistive element obtained as described above were measured. For comparison, a CoAg alloy film was formed directly on the substrate 1 with the same film thickness as in the example without forming a mask film in the manufacturing process of FIG. 1, and an electrode was formed on this magnetoresistive film. The magnetoresistive element of the example was produced, and the MR ratio and the operating magnetic field were measured in the same manner. Table 1 shows the results.

[0029]

[Table 1]

As is clear from Table 1, the magnetoresistive element in which the alloy film is formed in stripes according to the present invention has a high M.
The R ratio is shown, which shows that the operating magnetic field is small and the magnetic field sensitivity is high.

FIG. 3 is a diagram showing the magnetic field dependence of the MR ratio of Example 1 and Comparative Example 1. As is clear from FIG. 3, Example 1 according to the present invention exhibits a very high MR ratio. In this example, when a magnetic field was measured by applying a magnetic field in a direction perpendicular to the stripe extending direction,
The magnetic properties were almost the same as in Comparative Example 1.

Example 2 In the above example, instead of the CoAg alloy film, NiF was used.
A striped alloy film was formed in the same manner as in Example 1 except that the eAg alloy film was used. The composition of the alloy film was (Ni80Fe20) 20Ag80 (the numbers represent atomic%). Here, NiFe becomes a grain of a ferromagnetic substance and Ag becomes a non-magnetic substance.

The MR ratio and operating magnetic field of the magnetoresistive element obtained in the same manner as in the above example were measured. Further, a normal alloy film having no stripe shape was formed on the substrate in the same manner as in Example 1 to obtain a magnetoresistive element of Comparative Example 2. Table 2 shows the results.

[0034]

[Table 2]

As is clear from Table 2, the second embodiment according to the present invention exhibits a high MR ratio and a high magnetic field sensitivity, like the first embodiment. FIG. 4 is a diagram showing the magnetic field dependence of the MR ratio of Example 2 and Comparative Example 2. As is clear from FIG. 4, the magnetoresistive element of Example 2 exhibits a high MR ratio.

The ferromagnetic material and the non-magnetic material of the alloy film in the present invention are not limited to those in the above-mentioned embodiment, as long as they have a non-solid solution or eutectic relationship. Further, the method of forming the alloy film in a stripe shape having a predetermined width is not limited to that in the above-mentioned embodiment, and any method capable of forming the alloy film in a stripe shape may be used.

Further, in the first aspect according to the present invention, as long as the grains of the ferromagnetic material have shape anisotropy, the formation of the above-mentioned striped alloy film is not limited, and other Shape anisotropy may be imparted by a method.

[0038]

According to the first and second aspects of the present invention, a magnetoresistive element having a high MR ratio and a small operating magnetic field, that is, a high magnetic field sensitivity can be obtained.

According to the manufacturing method of the present invention,
The alloy film according to the first aspect and the second aspect can be manufactured by a simple process.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a manufacturing process of an embodiment according to the present invention.

2 is a plan view showing a state in which electrodes are provided on the magnetic alloy film obtained in the manufacturing process of FIG.

FIG. 3 is a diagram showing the magnetic field dependence of the MR ratio in Example 1 according to the present invention.

FIG. 4 is a diagram showing the magnetic field dependence of the MR ratio in Example 2 according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Mask film 2a ... Mask film stripe-shaped groove 3a ... Alloy film in stripe groove of mask film 3b ... Alloy film on mask film 4, 5 ... Electrode

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H01L 43/12 (72) Inventor Kazuhiko Kuroki 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Within Yo Denki Co., Ltd.

Claims (4)

[Claims] 1. An alloy film comprising a ferromagnetic material and a non-magnetic material in a non-solid solution or eutectic relationship with the ferromagnetic material, the ferromagnetic material forming grains in the non-magnetic material. A magnetoresistive element comprising: a grain of the ferromagnetic material having shape anisotropy. 2. An alloy film comprising a ferromagnetic material and a non-magnetic material which is in a non-solid solution or eutectic relationship with the ferromagnetic material, the ferromagnetic material forming grains in the non-magnetic material. A magnetoresistive element having a width in one direction of the alloy film of 1 μm or less. 3. The magnetoresistive element according to claim 2, wherein the alloy film is formed in a stripe shape and the width of the stripe is 1 μm or less. 4. An alloy film comprising a ferromagnetic material and a non-magnetic material which is in a non-solid solution or eutectic relationship with the ferromagnetic material, the ferromagnetic material forming grains in the non-magnetic material. A method of manufacturing a magnetoresistive element, comprising: forming a mask film in which a stripe-shaped groove having a width of 1 μm or less is formed on a substrate; and a substrate in the stripe-shaped groove and on the mask film. And a step of removing the mask film from the substrate to leave the alloy film in the stripe-shaped grooves of the mask film on the substrate to form a stripe-shaped alloy film. Device manufacturing method.