JPH11296816A - Magnetoresistance element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistance element in which the magnetic field sensitivity in a low magnetic field region is specifically improved and the element characteristic parameters closely related to the magnetic characteristic are precisely controlled independently of the material parameters a certain degree. SOLUTION: The magnetoresistance element 11 has a magnetic layer on a silicon substarate 10. The layer is provided with plural island regions 12 arranged in a matrix shape and magnetic thin lines 13 which mutually connect the regions 12. The shapes of the regions 12 are not limited to an approximate rectangular shape but also include circular, elliptical and cross shapes as well as polygonal shapes other than the rectangular shape. By intentionally controlling the network of the ferromagnetic island regions 12, which are formed into an arbitrary shape, and the lines 13, the magnetic domain structure (a unit magnetic domain structure and a magnetic wall moving type structure) and the saturated magnetization value are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element usable as a recording member such as a magnetic head or a magnetic recording medium, and more particularly to a magnetoresistive element having a magnetic layer on a substrate.

[0002]

2. Description of the Related Art Conventionally, in a magnetic recording medium such as a magnetic tape or a magnetic disk, a needle-like elongated ferromagnetic material is applied along a longitudinal direction which is a scanning direction of a base film. The recording density is determined by the number of magnetic poles per unit volume on the medium. In such a conventional longitudinal recording method, the positions and sizes of the magnetic poles are random, and the magnetization characteristics such as the recording density and the coercive force are almost defined by the material characteristics. In addition, since the acicular particles are oriented in random directions, the easy axis direction and the hard axis direction are randomly mixed on the same plane. Even in individual needle-like particles, a single domain structure and a multi-domain structure are mixed.

A conventional magnetoresistive element used in a magnetic head or the like mainly detects a magnetic field change using only a magnetization reversal mechanism based on the movement of a domain wall, and controls a single domain reversal mechanism. Impossible. In recent years, a giant magnetoresistive effect (GMR) having a multilayer artificial lattice of iron (Fe) and chromium (Cr) has been discovered, and a technique for applying this magnetoresistive effect has attracted attention. Strong coupling type G by this applied technology
The MR multilayer element, the weakly coupled GMR multilayer element, the non-coupled GMR multilayer element, the spin tunnel element, and the granular element will be described below.

First, as a typical structure of a strong coupling type GMR multilayer film element, a ferromagnetic metal film having a thickness of several nm and a nonmagnetic layer film made of Cr or the like are alternately and periodically laminated. There is something. When the spins in the upper and lower ferromagnetic layers separated by Cr are parallel under a strong applied magnetic field, spin scattering for electrons is reduced and the magnetoresistance is reduced. Conversely, when the applied magnetic field is weak and the spins in the upper and lower ferromagnetic layers are antiparallel, the magnetoresistance increases. Magnetoresistance has anisotropy, and there are two possible cases, namely, a case where a magnetic current is measured by flowing a current parallel to the film (CIP) and a case where the measurement is performed perpendicularly (CPP).

In general, the frequency of spin scattering and the magnetoresistance ratio of the CPP are higher than those of the CIP. The magnetoresistance ratio of the element in the CPP is as high as 100% or more at a low temperature, for example.
This is the ratio to the resistance in Gauss, and the magnetoresistance ratio per unit magnetic field is about 0.01% / Gauss, and the sensitivity is not so good.

FIG. 6 is a graph showing MH characteristics and magnetoresistive characteristics of a strong coupling type GMR multilayer device.
The sensitivity in the low magnetic field region is the same as that in the high magnetic field region. In this case, the magnetoresistance curve has a single peak structure having one peak near the zero magnetic field.

FIG. 7 is a graph showing MH characteristics and magnetoresistive characteristics of a weakly coupled GMR multilayer device.
The weak coupling type GMR multilayer film element is similar to the strong coupling type structure, but the non-ferromagnetic layer is thicker than the strong coupling type non-ferromagnetic layer, and the interaction between the ferromagnetic layers is weak. In this case, hysteresis characteristics are observed in the magnetic characteristics, and the magnetoresistance curve forms a double peak structure near a low magnetic field. Here, the non-ferromagnetic layer (non-ferromagnetic material) means a conductive material including a paramagnetic material and a diamagnetic material, that is, a conductive material other than a ferromagnetic material including metals and semiconductors. I have.

FIG. 8 is a graph showing MH characteristics and magnetoresistive characteristics of a non-coupling type GMR multilayer device.
The uncoupled GMR multilayer film element includes two types of magnetic materials having different coercive forces. For example, copper (Cu) having a thickness of 5 nm / thickness
A structure having 15 layers of 3 nm of cobalt (Co) / 5 nm of Cu / 15 nm of NiFe (permalloy) includes a NiFe layer having a small coercive force and a Co layer having a large coercive force. Permalloy reverses magnetization in a low magnetic field region, and the MH curve in that case has a constricted structure. The magnetoresistance characteristic of the uncoupled GMR multilayer film element is that a large change in resistance occurs in a low magnetic field, reflecting the change in magnetization.

[0009] The spin tunneling element is, for example, Ni-NiO-Co.
And Ni-NiO-Ni have a structure in which ferromagnetic metal layers are separated by insulator films. Generally, when utilizing the tunnel magnetoresistive effect, a current is passed in a direction perpendicular to the stack of the spin tunnel element having the stacked film structure, that is, in a direction perpendicular to the two-dimensional film. In the case of such an element structure, there are many structures whose size in the film surface direction is considerably larger than the film thickness of the element, and it is necessary to measure a small resistance value. Also, it is difficult to control the thickness of the insulator,
The reproducibility of the magnetoresistance is not good.

The granular element has a structure in which ferromagnetic particles such as iron and cobalt are deposited in a non-ferromagnetic metal such as silver and copper. In the weak magnetic field region, the magnetization of each particle is oriented in a random direction. Further, particles having a particle diameter of 10 nm or less have a very small coercive force and are in a superparamagnetic state in which the magnetization is almost proportional to the magnetic field. When a magnetic field of about several thousand gauss is applied, the spins of the granular element are aligned,
The magnetization saturates. The magnetoresistance ratio is about 8% for Co ₁₆ Cu ₈₄ and the magnetic field sensitivity is 0.001% / Gauss. This magnetic field sensitivity is one order of magnitude smaller than that of a strong coupling type GMR element, and the magnetization characteristics such as coercive force are not yet at a stage where they can be sufficiently controlled at the present time.

[0011]

In a conventional magnetoresistive element, for example, a strongly coupled (or weakly coupled) GMR element,
The vector sum of the magnetic field in which the spin of the ferromagnetic material is aligned and the magnetic resistance is minimized and the magnetic moment of the ferromagnetic material are approximately 0, and the magnetic field in which the magnetic resistance is maximized and the magnetic moment of the ferromagnetic material Is about several Tesla. For this reason, the magnetic field sensitivity in the low magnetic field region is low despite the high magnetoresistance ratio. In other words, since the needle-like magnetic domains are oriented in random directions, there is a range of uncertainty between the direction of the easy axis of magnetization and the direction of the hard axis of magnetization, and ideal sensitivity cannot be easily obtained.

In addition, element characteristic parameters closely related to magnetic characteristics, such as coercive force, saturation magnetization, and magnetic domain structure of ferromagnetic particles, in each of the above-described magnetoresistive elements are accurately and somewhat independent of material parameters. It was difficult to control. Although it has been observed in experiments that the granular type element has a high coercive force, it is also desirable to control the magnetic domain structure and magnetic characteristics of this element as in the case of the strong coupling type (or weak coupling type) GMR element. Has not been achieved.

In view of the above, the present invention improves the magnetic field sensitivity especially in a low magnetic field region, and enables a device characteristic parameter closely related to magnetic characteristics to be controlled to some extent independently and precisely from a material parameter. The purpose is to provide.

[0014]

In order to achieve the above object, the present invention provides a magnetoresistive element having a magnetic layer on a substrate, wherein the magnetic layers are arranged in a matrix. It is characterized by comprising a plurality of island-shaped regions and fine lines interconnecting the respective island-shaped regions.

According to the magnetoresistive element of the present invention, the magnetic field sensitivity is increased particularly in a low magnetic field region, and the element characteristic parameters such as the coercive force, the saturation magnetization, and the magnetic domain structure of the ferromagnetic particles are somewhat independent of the material parameters. And can be controlled precisely.

Here, the island region is preferably formed in a rectangular shape. In this case, the element can be designed so that a magnetic field can be applied in the short axis direction or the long axis direction of the rectangle.

Further, it is preferable that the shapes and / or areas of the island regions are different from each other. This makes it possible to adjust the coercive force of the magnetoresistive element.

More preferably, at least one of the island region and the thin line is formed in a multilayer film laminated structure. This allows
The sensitivity of the magnetoresistive element can be increased.

Preferably, the multilayer film in at least one of the island region and the thin line is made of a plurality of different materials. In this case, the coercive force and the saturation magnetization can be freely controlled by manufacturing the mutually intersecting rectangular-fine line arrays from different materials.

It is preferable that the axis of easy magnetization of at least one of the island region and the thin line is perpendicular to the pattern forming surface of the island region. Thereby, the island region is magnetized in the direction perpendicular to the substrate, and the number of bits per unit area increases, so that the recording density when the magnetoresistive element is used as a recording medium can be improved.

More preferably, a conductor film is further formed on an upper layer and / or a lower layer of at least one of the island region and the fine wire. In this case, it is possible to weaken the magnetic coupling between the fine wires and increase the holding force of the magnetoresistive element.

Further, it is preferable to control the magnetic characteristics by the shape anisotropy of each island region. Alternatively, instead of this, it is also a preferable embodiment to control the magnetic characteristics by the magnetic interaction between the island region and the fine wire. This simplifies the control of the magnetic properties.

It is preferable that the magnetoresistive element is configured as a storage element. Thereby, the use of the magnetoresistive effect element is expanded, and the recording density as a magnetic recording medium can be increased.

[0024]

The present invention will be described in more detail with reference to the drawings. FIGS. 1A and 1B are diagrams showing the structure of a dot network type magnetoresistive element according to an embodiment of the present invention. FIG. 1A is a plan view showing an example of the element structure, and FIG. (A) showing a state in which is a multilayer film structure
It is sectional drawing cleaved by the -Ib line.

The magnetoresistive element 11 has a silicon substrate 10 having a silicon oxide film 14 formed on the surface thereof, and a large number of islands made of magnetic materials arranged in a matrix on the silicon oxide film 14. It has a region 12. The island-shaped regions 12 are connected to each other by magnetic thin wires 13 in the form of a multilayer film extending in the vertical and horizontal directions perpendicular to each other. The plurality of island-shaped regions 12 are each formed in a substantially rectangular shape when viewed from above, and the rectangular areas in the vertical columns in FIG. 1A are different from each other. The island regions 12 and the magnetic thin wires 13 are formed as a multilayer film structure from several kinds of materials. When the magnetoresistive element 11 is used as a recording medium, for example, as shown in FIG.
The information recording / reproducing operation is performed by moving the magnetic head MH facing the magnetoresistive element 11 in the direction of the arrow. In addition, MLF in a figure shows a line of magnetic force, and C shows a coil.

In the island-shaped region 12 and the magnetic thin wire 13, there is an easy axis of magnetization in a direction perpendicular to the array surface (pattern forming surface) of the island-shaped region 12 (from the back to the front in FIG. 1A).
In addition, the upper layer portion (and / or
Or a lower layer portion), a conductor film is formed. In the magnetoresistive element 11 having such a configuration, the magnetic characteristics are controlled by utilizing the shape anisotropy of each of the island regions 12, or
Magnetic interaction between each island-like region 12 (each region 1
The magnetic characteristics can be controlled using the pitch between the two.

The island-shaped region 12 is not limited to a substantially rectangular shape, but can be formed in a circular shape, an elliptical shape, a cross shape, a polygonal shape other than a rectangular shape, or the like when viewed from above. The shape (and area) can be alternately changed for each row located in the direction, or the shape (and area) can be alternately changed for each row located in the left-right direction. Furthermore, the shape (and area) is alternately set for each island-shaped region 12 in the column direction.
Can be changed.

In the present embodiment, a network of the ferromagnetic island-like region 12 and the magnetic fine wire 13 which can be formed into an arbitrary shape is used.
By intentionally controlling the magnetic field, the magnetic domain structure (single magnetic domain structure, domain wall displacement structure) and the saturation magnetization value can be controlled.

When considering the case where the magnetoresistive effect element is used as a magnetic recording medium (storage element), in the conventional longitudinal recording method, the S pole and the N pole are on the same plane, and the single-domain structure and the multi-domain structure are different. Coexisted, and the area per magnetic domain could not be controlled satisfactorily, and there was a limit in improving the recording density. In order to further increase the recording density as a magnetic recording medium, it is desirable that each rectangular pattern (island-like region) has a single magnetic domain structure, and that each island-like region is perpendicular to the array surface of the silicon substrate. It is desirable that the magnets are regularly arranged in a magnetized state. In this embodiment, the periodic structure of the network between the island-shaped regions 12 and the magnetic fine wires 13 is formed by a multilayer film, so that the coupling force between the ferromagnetic layers separated by the non-ferromagnetic material is arbitrarily controlled. The magnetic sensitivity as a magnetoresistive element can be increased.

[0030]

EXAMPLE 1 FIG. 2 shows a magnetoresistive element 11 using a positive resist.
FIGS. 4A to 4F are diagrams illustrating a procedure for forming the image. FIGS. First, as shown in FIG. 2A, on a silicon oxide film 14 formed on the surface of the silicon substrate 10,
Two layers of polymethyl methacrylate (PMMA) resist films, that is, a high-sensitivity resist film 15 and a low-sensitivity resist film 16 were applied. The upper low-sensitivity resist film 16 has a thickness of about 50 nm, and the lower high-sensitivity resist film 15 has a thickness of about 2 nm.
00 nm. The sensitivity of the high-sensitivity resist film 15 is about 30
The sensitivity was set to 0 μC / cm ^2, which was higher than the sensitivity 400 μC / cm ² of the upper low-sensitivity resist film 16. This is to make the resist pattern developed after the electron beam writing into a divergent shape, and to facilitate lift-off after transferring the sputter and the deposited metal.

Next, as shown in FIG.
0 [pA], acceleration voltage 50 [keV], basic dose 4
By irradiating an electron beam of 00 μC / cm ² (electron beam lithography), a pattern of a rectangular-thin linear network was drawn. The drawn pattern has a height of 100 nm and a width of 5 nm.
A large island-shaped region 12 having an area of about 0 nm;
small island region 12 having an area of about 50 nm × width 50 nm
And the lateral size (width) of the magnetic thin wire 13 interconnecting the island regions 12 was formed to be about 20 nm. The pitch between the island regions 12 is about 400 nm. Further, after the pattern was drawn, development was performed for about 30 seconds in a mixed solution of methyl isobutyl ketone and isopropyl alcohol (mixing ratio 1: 1). Thereafter, in order to evaporate the developing solution, baking was performed in nitrogen gas for about 30 minutes.

Further, as shown in FIG.
The ferromagnetic film 23 was formed by a sputtering method. In addition, it was also confirmed that a similar film could be formed by an evaporation method other than the sputtering method. In the multilayer structure, 50 layers of Fe having a thickness of about 3 nm and Cr of about 1 nm were alternately laminated. Here, Fe was used for the ferromagnetic film 23. However, the iron surface is actually iron oxide, and the magnetic moment per unit volume at that portion is about 純 of that of pure iron.
Aluminum (Al), platinum (Pt), gold (A
u) or the like was attached as a protective film 22 on the surface of the ferromagnetic film 23 to cover it.

Next, as shown in FIG. 2D, after the ferromagnetic film 23 is formed, lift-off is performed in acetone to form a rectangular
-It was confirmed that the rows of the fine-line network were formed as designed.

Further, as shown in FIG.
A 1 μm thick PMMA resist is applied again and 500
Electrode pattern of about μm × 500μm (17 in FIG. 2 (f))
The electrode pattern area was exposed to an electron beam so that a pattern was formed over a plurality of (1000) rows of rectangular-fine linear networks. After the development, A
u was formed by sputtering to a thickness of about 100 nm. After this,
Lift-off was performed under the same conditions as described above. The thickness of Au is 20
The thickness may be about 0 nm, and platinum may be used instead of Au.

Next, as shown in FIG. 2F, a current was applied to the electrode pattern 17. At this time, the current flowed in the plane direction of the magnetoresistive element 11 because the electrode pattern 17 was on the same plane in the current process. That is, CIP
It was a structure. Further, in order to increase the sensitivity of the magnetoresistive effect element 11, the electrode can be processed as a CPP structure in which a current flows in a direction perpendicular to the element surface. In this case,
A method in which a pair of lower electrodes is formed on the silicon substrate 10 on which the silicon oxide film 14 is formed, a rectangular-fine line is formed, and a pair of upper electrodes is formed above the magnetic wire 13. Take.

Embodiment 2 In this embodiment, a rectangular-thin linear network pattern is formed using a negative resist. FIG. 3 is a diagram showing this forming method, and (a) to (f) are diagrams showing each procedure.

First, as shown in FIG. 3A, an Fe film 18 having a thickness of about 20 nm is formed on the silicon oxide film 14 formed on the surface of the silicon substrate 10, and the Fe film 18 is formed on the Fe film 18. Then, a Pt film 19 having a thickness of about 2 nm is formed by sputtering.
When the Fe film 18 has a multilayer structure, the F
A large number of e films 18 and nonmagnetic layer films 20 of about 1 nm made of Cr are alternately and periodically laminated. Note that an evaporation method can be used for film formation.

Further, as shown in FIG.
High resolution negative resist from above
After applying 21 to a thickness of about 1 μm, the electron beam
The pattern was drawn with a rectangular-thin line array using a system and developed. In this case, the acceleration voltage was 50 [keV], and the beam current was 100 [pA]. Here, an Al film can be formed instead of the Pt film 19.

Next, as shown in FIG. 3C, etching was performed with argon (Ar) gas. In this case, the Ar gas pressure is about 5 × 10 ⁻⁵ [Torr], and the time required for the treatment is about 45.
Seconds. As a result, the negative resist film 21, the Pt film 19, and the Fe film 18 are sequentially etched, and the silicon substrate 1 is etched.
The process was stopped when the silicon oxide film 14 on the zero appeared. A negative resist film 21 is formed to be about 1 μm thick,
The Fe on the magnetic fine wire 13 was not etched.

Thereafter, as shown in FIG. 3 (d), the negative resist film 21 remaining on the upper part of the rectangular-thin line was removed by an oxygen plasma washer. FIG. 3E shows the rectangular-thin linear row in this state when viewed from above.

Further, as shown in FIG.
An electrode pattern was formed by a system, and after development, Au was sputtered to form an electrode 17. The conditions for pattern formation and film formation were set in the same manner as in the method using the positive resist of the first embodiment. Note that Au is used for sputtering on the electrode 17.
Can be used instead of platinum, and an evaporation method can be used instead of the sputtering method.

The structure has been briefly described above according to the manufacturing method. However, the multilayer film may have a structure in which Co and Cr are alternately laminated, for example, and the pattern forming method is an electron beam method. It is not limited.

Next, the magnetic characteristics of the magnetoresistive effect element 11 to which the present invention is applied will be described in more detail by taking the rectangular-wire network structure in the above embodiment as an example.
As shown in FIGS. 1 (a) and 1 (b), when a magnetic field is applied to a rectangular-fine wire network, the magnetization is measured. In the size region, the coercive force (magnetic field H1) of the rectangle having the smaller area is smaller than the coercive force (magnetic field H2) of the rectangle having the larger area.

Using two pairs of four electrodes (see FIG. 2 (f)) attached to the magnetoresistive element 11 having the rectangular-fine line structure, the magnetoresistance characteristics were measured by a four-terminal method. FIG.
Is a graph showing the measurement results of the characteristics of the magnetoresistive effect element, (a) shows the magnetic characteristics (hysteresis loop),
(b) shows magnetoresistance characteristics.

As a result of the measurement, the magnetic characteristics of the magnetoresistive element are such that the magnetization of the small island area 12 is reversed in the same direction as the magnetic field under a magnetic field H1 of about 40 Gauss. Reflecting this situation, the magnetic resistance has a discontinuous jump in the magnetic field H1. In this case, 40 [Ω] to 80 [Ω]
That is, the MR ratio was 100% and the magnetic sensitivity was 1.6% / Gauss. The magnitude of the jump was proportional to the total volume of the smaller island region 12 in the volume of the ferromagnetic material of the entire magnetoresistive element. Further, a magnetic field is applied until the magnetization of the larger island-shaped region 12 is reversed (100 fields up to the magnetic field H2).
Gauss) The magnetization of the element does not change much, the magnetoresistance shows a gradual change, and all the spins in the element are aligned in the direction of the magnetic field with the magnetic field H2, and the magnetoresistance suddenly changes from 80 [Ω] to 40 [Ω]. Has dropped.

In the embodiment shown in FIG. 1, the rectangular and thin linear rows which are orthogonal to each other have the same thickness and thickness, but the thickness and thickness of the magnetic thin wires 13 which are orthogonal to each other are reduced. It is also possible to change the angle or to change the angles of the individual island regions 12 with respect to the magnetic field. For example, a magnetic field is applied in a long axis direction or a short axis direction of a rectangle. Alternatively, it has been confirmed that the coercive force and the saturation magnetization can be freely controlled by manufacturing mutually intersecting rectangular-magnetic fine wire rows with different materials.

In this description, it is assumed that a magnetic field is applied in the long axis direction of two large and small rectangles. Now, when a magnetic field is applied in the minor axis direction of the larger (100 nm × 50 nm, 2 × 107) and the smaller island-shaped regions 12 (50 nm × 40 nm, 5 × 107), the larger and smaller islands are applied. Are 80 gauss and 30 gauss, respectively. When the magnetoresistance is measured by attaching an electrode terminal to the magnetoresistance effect element, the magnetoresistance changes from 40 [Ω] to 70 [Ω] at 30 Gauss, and only the smaller island region 12 is oriented in the same direction as the magnetic field. Spin reverse. At this time, the resistance value is 8
It is almost constant up to 0 Gauss, the resistance at 80 Gauss decreases from 70 [Ω] to 40 [Ω], and all spins tilt in the direction of the magnetic field.

The magnetoresistance ratio is 75%. Here, 2
Considering the arrangement of the island regions 12 of different kinds, for example, if N kinds of rectangular-thin lines are formed, N digital steps can be realized (if there are N kinds of coercive forces) and only a low magnetic field is used. Instead, a highly sensitive magnetoresistive element can be realized even in a high magnetic field region.

A method for producing individual rectangles with different materials in such a structure will be specified. For example, consider a structure in which two types of rectangles, large and small, are connected by a thin line. First,
A PMMA resist is applied, and a network of large island regions 12 is formed by electron beam lithography. In this case, the accelerating voltage is 50 eV, the beam current is 100 pA, and the electron beam dose is 400 μC / cm ^2.
It is.

After development, about 20 nm of Fe is deposited by ion beam sputtering, and lift-off is performed with acetone.
Next, a PMMA resist is applied again, a mark is detected by an aligner or the like, and the smaller rectangle is overlapped and exposed. In this case, it is connected to the larger rectangular-thin line. This time, a permalloy is attached and lifted off by ion beam sputtering, and a dot network type magnetoresistive element is completed. In this case, two processes are required, but the holding power of the permalloy element is reduced in the small island region 12, and the sensitivity is improved as compared with the case where the element is entirely made of Fe. The holding force in this case is about 10 Gauss. To make this structure function as a magnetic recording medium,
A higher magnetic density per unit volume is preferred.

In the above structure, each rectangle is represented by 100
nm or less, each rectangular island region 12
Each has a single magnetic domain structure and is 1 bit. At this time, compared to the case where a single magnetic domain is formed in a direction parallel to the substrate,
In the case of magnetization in the vertical direction, the number of bits per unit area can be increased. Increase the aspect ratio of Fe to about 20 nm in diameter and about 50 nm in height
If so, the rectangular pattern is magnetized in the direction perpendicular to the silicon substrate, and the recording density when used as a recording medium is improved. Alternatively, an alloy of cobalt chromium, barium ferrite, or the like can be used as the perpendicular magnetization element.

In the case of a magnetoresistive element in which rectangles of about 100 nm are arranged at a pitch of about 100 nm, the mutual interaction of the rectangular dipoles is strong (inversely proportional to the cube of the distance and the mutual rectangular magnetic motors). −proportion-product), the coercive force of the magnetoresistive element is reduced. If the pitch is 10
If it exceeds 0 nm, the holding power of the element gradually increases.
In other words, in order to increase the sensitivity in a low magnetic field as a magnetoresistive effect element, it is preferable to narrow the pitch of the rectangular-thin lines, and to increase the sensitivity in a higher magnetic field, the pitch is increased. An artificial lattice magnetoresistance effect element (F
In e-Cr and Co-Cu), if the number of laminations is increased, the frequency of spin scattering is increased and a larger change in magnetoresistance can be obtained. This phenomenon is also observed in the nanostructured device according to the present invention, and by adopting the multilayer structure, the magnetoresistance ratio and the magnetic field sensitivity are improved.

Next, a description will be given of a second embodiment in which the gaps between the rectangular and thin linear networks are electrically connected by non-magnetic conductors. FIG. 5 is a cross-sectional view showing a structure in which a Cr-film is coated on a multi-layered rectangular-fine network of Fe and Cr in this embodiment.

First, on the silicon oxide film 14 of the silicon substrate 10, a rectangular-fine linear network (ferromagnetic film 23) is formed from Fe, and then a film is formed as a conductor film covering the network. A Cr film 25 of about 20 nm was formed from above by sputtering. Thereby, Fe and Cr
The periodic structure of the rectangular-fine wire network can be obtained. When the spins of Fe on both sides of Cr are aligned (H> 100 Gauss), the magnetic resistance is minimized, and the spins on both sides are antiparallel in a low magnetic field region. (40 Gauss <H <100 Gauss), the magnetic resistance became maximum. In this case, for example, the interval between the magnetic thin wires 13 is about 400 nm, and the rectangular pattern (the island region 12) is used.
Is too large to reach the magnetic interaction, there is no magnetic coupling between the magnetic thin wires 13 and the coercive force of the magnetoresistive effect element increases.

Conversely, if the rectangular pitch is narrowed, the dipole interaction becomes stronger, and the coercive force of the magnetoresistive element decreases. Now, the island region 12 which is a dot of Fe is formed by the Cr film 2.
Although the case of coating with 5 is considered, a copper film may be coated on a rectangular pattern of Co thin wires. In addition, it was confirmed that the sputtering method may be replaced by a vapor deposition method. In a conventional granular-type magnetoresistive element, the distribution and size of each ferromagnetic fine particle are random, and a single domain structure and a multi-domain structure coexist. A typical method of manufacturing this magnetoresistive element is to simply sputter the alloy and perform an appropriate heat treatment.

According to the above method, the production is easy,
The shape of ferromagnetic particles generally includes a mixture of circles, ellipses, and rectangles, and important parameters such as shape anisotropy and coercive force are not controlled at this time. In the method to which the present invention is applied,
It is possible to form a rectangle or a thin wire at any size and position. To increase the holding power of the element, a maximum of 2500 can be obtained by applying a magnetic field in the direction of the axis of easy magnetization by applying a needle-like Fe process.
It is possible to increase the holding power to about Gauss. Further, in order to reduce the coercive force of the magnetoresistive effect element to about several tens of gauss, the area of the rectangle is reduced (50 nm or less),
Alternatively, heat treatment is performed. Furthermore, the element can be designed so that a magnetic field can be applied in the direction of the short axis of the rectangle.

As described above, according to the embodiment and the examples of the present invention, by controlling the fine processing of the pattern of the rectangular-thin line array, it is possible to perform recording as a magnetic recording medium or a magnetic head or the like. A highly sensitive magnetoresistive element that can be used as a member can be obtained. In addition, since the element can be processed into an arbitrary shape by the fine processing technology, the magnetoresistance value can be set to an arbitrary value. For example, when it is desired to increase the resistance value, the film thickness or the width of the magnetic fine wire may be reduced, the cross-sectional area of the magnetoresistive element may be reduced, and the magnetic fine wire may be lengthened. This is an advantage that the conventional low resistance value tunnel current element (TMR structure) does not have.

Furthermore, magnetic fine wires, shape anisotropy of island-like regions,
By providing a multilayer structure, it is possible to freely control the magnetic characteristics of the magnetoresistive effect element, in particular, the coercive force, the saturation magnetization, the gradient (magnetic field sensitivity) of the magnetoresistance (including the hysteresis characteristics), and the like. In particular, the MR ratio sensitivity in a low magnetic field is increased, the high resistance region is expanded, and the saturation magnetization can be freely controlled. For example, to improve the coercive force, the element is designed so that a magnetic field is applied in the longitudinal direction of the regularly arranged island regions (rectangles). The size may be further reduced. Further, the technology according to the present invention is based on the fact that individual patterns are formed in a single magnetic domain structure by processing a ferromagnetic material on a nanoscale and arranged at a high density. A recording medium can also be obtained. In addition,
In this embodiment, iron is used as the ferromagnetic material. However, the present invention is not limited to this, and any other material can be applied to the ferromagnetic material.

Although the present invention has been described based on the preferred embodiments, the magnetoresistive effect element of the present invention is not limited to the configurations of the above-described embodiments and examples. Magnetoresistive elements obtained by making various modifications and changes from the configurations of the embodiment and the examples are also included in the scope of the present invention.

[0060]

As described above, according to the magnetoresistive effect element of the present invention, the magnetic field sensitivity is improved particularly in a low magnetic field region, and the element characteristic parameters closely related to the magnetic characteristics are somewhat independent of the material parameters. And can be controlled precisely.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing a structure of a magnetoresistive element according to an embodiment of the present invention, wherein FIG. 1A is a plan view showing an example of the element structure, and FIG. It is sectional drawing.

FIG. 2 is a diagram showing a procedure in Example 1 for forming a magnetoresistive element using a positive resist, and FIGS.
(f) is a diagram showing each procedure.

FIG. 3 is a diagram showing a procedure in Example 2 for forming a magnetoresistive element using a negative resist, and FIGS.
(f) is a diagram showing each procedure.

FIGS. 4A and 4B are graphs showing measurement results of characteristics of a magnetoresistive element, wherein FIG. 4A shows magnetic characteristics and FIG. 4B shows magnetoresistive characteristics.

FIG. 5 is a cross-sectional view showing a structure in which a Cr film is coated on a multilayer rectangular-fine network.

FIG. 6 shows M in a conventional strong-coupling type GMR multilayer device.
4 is a graph showing -H characteristics and magnetoresistance characteristics.

FIG. 7 is a graph showing M in a conventional weak-coupling type GMR multilayer device;
4 is a graph showing -H characteristics and magnetoresistance characteristics.

FIG. 8 shows M in a conventional non-coupled GMR multilayer device.
4 is a graph showing -H characteristics and magnetoresistance characteristics.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 silicon substrate 11 magnetoresistive element 12 island region 13 magnetic wire 14 silicon oxide film 18 Fe film 19 Pt film 25 Cr film

Claims (10)

[Claims] 1. A magnetoresistive element having a magnetic layer on a substrate, wherein the magnetic layer includes a plurality of island-shaped regions arranged in a matrix and thin wires interconnecting the island-shaped regions. A magnetoresistive element comprising: 2. The magnetoresistive element according to claim 1, wherein said island region is formed in a rectangular shape. 3. The magnetoresistive element according to claim 1, wherein the island regions have different shapes and / or areas. 4. The magnetoresistive element according to claim 1, wherein at least one of the island region and the thin line has a multilayer structure. 5. The magnetoresistive element according to claim 4, wherein the multilayer film in at least one of the island region and the fine wire is made of a plurality of different materials. 6. The semiconductor device according to claim 1, wherein the axis of easy magnetization of at least one of the island region and the thin line is perpendicular to a pattern forming surface of the island region.
6. The magnetoresistive element according to any one of Items 5 to 5. 7. The semiconductor device according to claim 1, wherein a conductive film is further formed on an upper layer and / or a lower layer of at least one of the island region and the fine wire. Magnetoresistive element. 8. The magnetic characteristics are controlled by the shape anisotropy of each of said island-shaped regions.
The magnetoresistive element according to any one of the above. 9. The magnetoresistive element according to claim 1, wherein a magnetic characteristic is controlled by a magnetic interaction between the island region and the fine wire. 10. The magnetoresistive element according to claim 1, wherein the magnetoresistive element is configured as a storage element.