JP2001267522A - Magnetic memory element and magnetic memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the problem where since a laminated film which consists of two ferromagnetic layers coupled antiferromagnetically via a metal layer is used for a free layer (memory layer) in the conventional magnetic memory element, the memory layer is difficult to manufacture and the influence by the end magnetization cannot be reduced sufficiently and smooth inversion of magnetization of the memory layer is difficult to achieve and the power consumption of a magnetic memory cannot be reduced. SOLUTION: On the ferromagnetic layer 14 which is to become the memory layer of the magnetic memory element, the ferromagnetic layer 16 is formed via at least one conductor layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic memory element using a magnetoresistance effect and a magnetic memory using the same.

[0002]

2. Description of the Related Art Anisotropic magnetoresistance effect (AM)
Applications of R) elements, giant magnetoresistive (GMR) elements, and magnetic tunnel junction (MTJ) elements to HDD read heads and magnetic memories are being considered. A magnetic memory is a solid-state memory that has no moving parts like a semiconductor memory, but does not lose information even when the power is turned off, has an infinite number of repetitions, and loses the recorded contents even if radiation is incident It is more useful than a semiconductor memory because it has no properties.

In particular, the MTJ element has a large rate of change in resistance, and is therefore expected to be used for a memory cell. FIG. 9 shows a configuration of a conventional MTJ element. Such a structure is disclosed, for example, in Japanese Patent Application Laid-Open No. 9-106514. The MTJ element in FIG. 9 has an antiferromagnetic layer 61, a ferromagnetic layer 62, an insulating layer 63, and a ferromagnetic layer 64 stacked. Here, as the antiferromagnetic layer 61, FeMn, NiM
Alloys such as n, PtMn, and IrMn are used, and the ferromagnetic layers 62 and 64 are made of Fe, Co, Ni, or an alloy thereof. Various oxides and nitrides have been studied for the insulating layer 63, but it is known that the highest magnetoresistance (MR) ratio can be obtained with an Al ₂ O ₃ film.

[0004] In addition, there has been proposed an MTJ element using a difference in coercive force between the ferromagnetic layer 62 and the ferromagnetic layer 64 without the antiferromagnetic layer 61.

FIG. 10 shows the operation principle when the MTJ element having the structure shown in FIG. 9 is used for a magnetic memory. The magnetizations of the ferromagnetic layer 62 and the ferromagnetic layer 64 are both in the plane of the film and have an effective uniaxial magnetic anisotropy such that they are parallel or antiparallel. The magnetization of the ferromagnetic layer 62 is
1 is substantially fixed in one direction by exchange coupling, and holds recording in the direction of magnetization of the ferromagnetic layer 64.

The ferromagnetic layer 64 serving as a memory layer detects whether the magnetization of the ferromagnetic layer 64 is parallel or anti-parallel and the resistance of the MTJ element is different, performs reading, and utilizes a magnetic field generated by a current line arranged near the MTJ element. Then, writing is performed by changing the direction of magnetization of the ferromagnetic layer 64.

By the way, in the MTJ element having the above structure, the magnetization of the ferromagnetic layers 62 and 64 is in the in-plane direction, so that magnetic poles are generated at both ends. As a result, such M
When a memory array is formed with TJ elements, magnetostatic interaction occurs between MTJ elements. This is an individual MTJ
This means that the characteristics of the element are affected by the state of the adjacent MTJ element, which makes it difficult to increase the recording density by narrowing the interval between the MTJ elements. To cope with such a problem, Japanese Patent Application Laid-Open No. H11-161919 discloses a method of reducing the influence of end magnetic poles. FIG. 11 shows this structure. According to this, a ferromagnetic layer 62 (fixed layer) whose magnetization direction is fixed by being coupled to the antiferromagnetic layer 61 and a ferromagnetic layer 64 (free layer) that can freely rotate with respect to an external magnetic field.
Are laminated via an insulating layer 63. Further, both the ferromagnetic layer 62 and the ferromagnetic layer 64 are formed of the nonmagnetic metal layer 72,
Two ferromagnetic layers 7 antiferromagnetically coupled via 75
1, 73 and 74, 76. Therefore, it is possible to reduce the number of magnetic poles generated at the ends in both the free layer and the fixed layer.

[0008]

However, Japanese Patent Application Laid-Open No.
The ferromagnetic layer (free layer) not adjacent to the antiferromagnetic layer in JP-A-161919 is made of NiFe / Ru / NiFe, and rotates freely by application of an external magnetic field. In the embodiment, the Ru film thickness is set so that the two NiFe layers have the maximum antiferromagnetic coupling strength, and the two NiF layers have the same thickness.
The thickness of the e-layer is set to be slightly different. The operation of the free layer when a magnetic field is applied is represented by two NiFe
This is achieved by the rotation of the net magnetization caused by the layer thickness difference.

However, the film thickness of Ru, in which the two NiFe layers have the maximum antiferromagnetic coupling strength, is extremely thin, 4 ° to 8 °, and when pinholes occur, conversely, ferromagnetic coupling occurs. It is difficult to stably obtain the antiferromagnetic coupling strength. In addition, in order for magnetization reversal to occur due to an external magnetic field, the two NiFe layers need to have different thicknesses.
As a result, the net magnetization as viewed from the outside cannot be reduced to zero, and the original purpose cannot be achieved. Furthermore, when used as a magnetic memory element, a magnetic field required to cause magnetization reversal is generated by a current flowing through an adjacent conductor line, but nothing is described about a configuration for reducing power consumption. Absent.

Further, in the prior art, when used in a magnetic head, the applied magnetic field and the hard layer direction of the free layer are used in an arrangement orthogonal to each other, but when used in a magnetic memory device, it is usually used on a magnetic memory device. Since the magnetization of the free layer is rotated by the magnetic field generated by the two intersecting conductor lines, the applied magnetic field is inclined obliquely to the hard axis direction of the free layer. Therefore, it is unlikely that magnetization reversal due to simple magnetization rotation occurs as described in the prior art, and it is difficult to use an element having this configuration as a magnetic memory element.

In order to solve the above-mentioned problems, the present invention provides a magnetic memory element and a magnetic memory in which a magnetization state recorded in a memory layer exists stably even when a pattern is miniaturized and power consumption is small. With the goal.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and a first invention is a magnetic memory having at least a first magnetic layer, a non-magnetic layer, and a second magnetic layer laminated. The device is characterized in that a third magnetic layer is provided on at least one side of the first or second magnetic layer different from the non-magnetic layer lamination side via at least one conductor layer.

According to a second aspect, in the first aspect, the magnitude of the magnetization of the third magnetic layer is substantially equal to the magnitude of the magnetization of the first or second magnetic layer in contact with the conductor layer.

According to a third aspect, in the first aspect, the third aspect is provided.
The coercive force of the magnetic layer is smaller than the coercive force of the first or second magnetic layer in contact with the conductor layer.

According to a fourth aspect, in any one of the first to third aspects, a second conductor layer is provided between the conductor layer and the third magnetic layer.

According to a fifth aspect of the present invention, in any one of the first to third aspects, a second conductor layer is provided outside the first magnetic layer or the third magnetic layer. First
The ferromagnetic material layer is in contact with the side not facing the magnetic layer or the third magnetic layer.

According to a sixth aspect, in any one of the first to fifth aspects, the nonmagnetic layer sandwiched between the first magnetic layer and the second magnetic layer is an insulator.

According to a seventh aspect of the invention, there is provided a magnetic memory using the magnetic memory element according to the first to sixth aspects.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 shows a configuration example of a first embodiment according to the present invention. As shown in FIG. 1, the magnetic memory element 1 according to the present embodiment uses an MTJ element,
Ferromagnetic layer 12 (fixed layer), insulating layer 13, ferromagnetic layer 14
(Free layer), conductor layer 15, ferromagnetic layer 16, insulating layer 17,
The conductor layer 18 is formed. In this embodiment, the fixed layer 12 is composed of a laminated film of the ferromagnetic layer 19, the metal layer 20, and the ferromagnetic layer 21.
Are selected so as to have antiferromagnetic coupling, and the ferromagnetic layers 19 and 21 are selected so as to have substantially equal magnetizations.
The fixed layer 12 may be formed of a single-layer ferromagnetic material. However, by adopting such a laminated structure, the magnetic pole generated at the end of the fixed layer 12 can be made substantially zero.

The ferromagnetic layer 12, ferromagnetic layer 14, and ferromagnetic layer 16 are given uniaxial anisotropy in a direction parallel to the plane of the drawing, and the antiferromagnetic layer 11 and the ferromagnetic layer 19 are exchange-coupled. ing. In the magnetic memory element of the present embodiment, two states are created in which the magnetizations of the ferromagnetic layer 21 and the ferromagnetic layer 14 constituting the fixed layer 12 are parallel or antiparallel to each other. In this embodiment, the conductor layer 15 also serves as a bit line and an electrode for detecting a change in resistance, and is connected to an adjacent magnetic memory element at an interval determined by a wiring rule. The conductor layer 18 is a word line. Here, as shown in FIG. 1, a current flows through the conductor layer 15 perpendicularly to the plane of the paper, and a current flows through the conductor layer 18 parallel to the plane of the paper. FIG. 2 shows a magnetic field generated at the positions of the ferromagnetic layer 14 and the ferromagnetic layer 16 by two currents when viewed from a direction perpendicular to the film surface. Thus, the conductor layer 15 is located at the position of the ferromagnetic layer 14 and the ferromagnetic layer 16.
The combined magnetic field of the magnetic field H _W by the magnetic field H _B and the conductor layer 18 due to is applied. As shown in FIGS. 2A and 2B, since the directions of the combined magnetic fields are different between the positions of the ferromagnetic layer 14 and the ferromagnetic layer 16, a strong uniaxial anisotropy is given in the horizontal direction of the drawing. The magnetic layers 14 and 16 are magnetized in different directions. Therefore, the magnetization of the ferromagnetic layer 14 is stabilized by the magnetic field generated by the magnetic poles generated at both ends of the ferromagnetic layer 16. Further, by making the magnitudes of the magnetizations of the ferromagnetic layer 14 and the ferromagnetic layer 16 substantially equal, the magnetization is apparently lost to the outside, and the adjacent magnetic memory element is not affected. Furthermore, the ferromagnetic layer 14 and the ferromagnetic layer 1
Since the conductor layer 15 is in direct contact with 6, a sufficient magnetic field strength can be obtained even with a small current, and low power consumption of the magnetic memory element can be realized.

As another form of this embodiment, as shown in FIG. 3, a structure in which a conductor layer 28 is provided on an opposite side of the antiferromagnetic layer 11 from the ferromagnetic layer 12 with an insulating layer 27 interposed therebetween. Can also. FIG. 4 shows that the ferromagnetic layer 1
4 shows the magnetic field generated at the position of the ferromagnetic layer 4 and the ferromagnetic layer 16 when viewed from the direction perpendicular to the film surface. As in the arrangement of FIG. 1, the magnetization of the ferromagnetic layer 14 is stabilized by the magnetic field generated by the magnetic poles generated at both ends of the ferromagnetic layer 16.

The material of the antiferromagnetic layer 11 is FeMn,
Alloys such as NiMn, PtMn, and IrMn can be used, and the material of the ferromagnetic layers 12, 14, 16 is Fe,
Co, Ni, or an alloy thereof can be used. The insulating layer 13 is preferably an Al ₂ O ₃ film from the viewpoint of MR ratio, but may be another insulating film such as an oxide film or a nitride film, or may be a Si film, a diamond film, or a diamond-like carbon (DLC). It may be an insulating film such as a film.

The thickness of the ferromagnetic layers 12, 14, 16 is 10
It is desirable that it be Å or more. If the film thickness is too thin, it becomes superparamagnetic under the influence of heat energy. Therefore, the thickness of the magnetic layer is desirably 10 ° or more. It is preferable that the thickness of the insulating layer 13 is not less than 3 ° and not more than 30 °. This is because when the thickness of the insulating layer 13 is 3 mm or less,
There is a possibility that the ferromagnetic layer 12 and the ferromagnetic layer 14 are electrically short-circuited. If the thickness of the insulating layer 13 is 30 ° or more, tunneling of electrons hardly occurs and the magnetoresistance ratio becomes small. is there.

Next, FIG. 5 shows a configuration example of the second embodiment according to the present invention.

As shown in FIG. 5, the magnetic memory element according to the present embodiment uses an MTJ element as in the first embodiment.
It comprises an antiferromagnetic layer 11, a ferromagnetic layer 12, an insulating layer 13, a ferromagnetic layer 14, a conductor layer 15, an insulating layer 37, a conductor layer 38, and a ferromagnetic layer 16. The ferromagnetic layers 12, 14, 16 have uniaxial anisotropy in a direction parallel to the plane of the drawing. Further, as in the first embodiment, the ferromagnetic layer 12 is a laminated film, and the antiferromagnetic layer 11 and the ferromagnetic layer 19 are exchange-coupled. Note that the materials and thicknesses of the respective layers can be the same as those in the first embodiment.

In this embodiment, a current flows through the conductor layer 15 perpendicular to the plane of the drawing, and a current flows through the conductor layer 38 parallel to the plane of the drawing. FIG. 6 shows the magnetic field generated at the positions of the ferromagnetic layer 14 and the ferromagnetic layer 16 by the two currents when viewed from a direction perpendicular to the film surface. The ferromagnetic layer 14 and ferromagnetic layer 16, (a), (b), the combined magnetic field of the magnetic field H _B and the magnetic field H _W created by the current flowing through the conductor layer 15 and the conductor layer 38 is applied . In this film configuration, the combined magnetic field is directed substantially antiparallel at the positions of the ferromagnetic layers 14 and 16. As a result, the magnetic poles generated in the respective ferromagnetic layers in the process until the magnetization is reversed at the time of recording act in directions that promote the respective magnetization reversals. Therefore, the recording current can be further reduced as compared with the first embodiment.

Next, FIG. 7 shows a configuration example of the third embodiment according to the present invention.

As shown in FIG. 7, the magnetic memory element according to the present embodiment uses an MTJ element as in the first embodiment.
It comprises an antiferromagnetic layer 11, a ferromagnetic layer 12, an insulating layer 13, a ferromagnetic layer 14, a conductor layer 15, a ferromagnetic layer 16, an insulating layer 47, a conductor layer 48, and a ferromagnetic layer 49. Ferromagnetic layers 12, 14, 1
No. 6 has uniaxial anisotropy in a direction parallel to the paper surface. Further, as in the first embodiment, the ferromagnetic layer 12 is a laminated film, and the antiferromagnetic layer 11 and the ferromagnetic layer 19 are exchange-coupled. Note that the materials and thicknesses of the respective layers can be the same as those in the first embodiment.

In this embodiment, a current flows through the conductor layer 15 in a direction perpendicular to the plane of the drawing, and a current flows through the conductor layer 48 in a direction parallel to the plane of the drawing. Ferromagnetic layer 14 and ferromagnetic layer 16
The direction of the magnetic field applied to is the same as in FIG. 4 of the first embodiment. In this embodiment, a ferromagnetic layer 49 having a high magnetic permeability is in contact with a side of the conductor layer 48 that does not face the antiferromagnetic layer 11. During recording, a current flows through the conductor layer 48 to generate a magnetic field. However, since the ferromagnetic layer 49 has a high magnetic permeability, the magnetic field on the ferromagnetic layer 49 side of the conductor layer 48 concentrates on the ferromagnetic layer 49. As a result, the magnetic field on the opposite side of the ferromagnetic layer 49 of the conductor layer 48 becomes large, and even if the same current flows, the ferromagnetic layers 14 and 16 serving as the recording layers are compared with the case where the ferromagnetic layer 49 is not provided. The magnetic field strength at the position is increased. Therefore, the power consumption of the magnetic memory can be reduced as compared with the case where the ferromagnetic layer 49 is not provided. The ferromagnetic layer 49 has a NiFe alloy, C
A high magnetic permeability alloy such as an oZrNb-based amorphous alloy or a FeAlSi-based alloy can be used. In this embodiment, the case where the current line is arranged below the element is shown. However, the same effect can be obtained when the current line is arranged above the element.

Next, FIG. 8 shows a schematic diagram when the magnetic memory element 1 of this embodiment is used for a magnetic memory which can be accessed randomly.

The transistor 51 has a role of selecting the magnetic memory element 1 at the time of reading. “0”, “1”
Is recorded by the magnetization direction of the ferromagnetic layer 14 of the magnetic memory element 1 shown in FIG. 1, and the magnetization direction of the ferromagnetic layer 12 is fixed. Information is read using the magnetoresistance effect that the resistance value is low when the magnetizations of the ferromagnetic layers 12 and 14 are parallel and high when the magnetizations are antiparallel. On the other hand, writing is performed on the bit line 52 and the word line 5.
This is realized by reversing the magnetization directions of the ferromagnetic layer 14 and the ferromagnetic layer 16 by the synthetic magnetic field formed by the ferromagnetic layer 3. In addition, 54 is a plate line.

In the above embodiment, the magnetization of the ferromagnetic layer 12 is fixed by exchange coupling with the antiferromagnetic layer 11,
Other means such as using a ferromagnetic material having a large coercive force as the fixed layer 12 can be used. Further, even if the ferromagnetic layer 12 is made of a ferrimagnetic material such as a rare earth-transition metal alloy film having a composition near the compensation point, the influence of the magnetic pole at the end can be reduced.

It is also possible to stack the layers in the reverse order.

Further, in the embodiment according to the present invention, by setting the coercive force of the ferromagnetic layer 16 smaller than the coercive force of the ferromagnetic layer 14, the magnetization of the ferromagnetic layer 16 is first reversed during recording. Can be done. As a result, the magnetic poles generated at both ends of the ferromagnetic layer 16 generate a magnetic field in a direction that promotes the reversal of the magnetization direction of the ferromagnetic layer 14, and the current required for recording can be further reduced.

Although only the magnetic memory element portion is shown in the above-described embodiment, it is apparent that an electrode, a substrate, a protective layer, an adhesion layer, and the like on the current outflow side are required in actual element formation. .

Further, in the above embodiment, the MTJ element has been described as an example, but the antiferromagnetic layer 11 which is a memory element portion,
A GMR element can also be used if the conductor layer is insulated from the laminated portion of the ferromagnetic layer 12, the nonmagnetic layer 13, and the ferromagnetic layer 14.

[0038]

As described above, the magnetic memory element of the present invention can stabilize the magnetization of the recording layer and reduce the influence between adjacent magnetic memory elements.
Even if the pattern is miniaturized, a stable magnetization state can be maintained. Therefore, a magnetic memory with a higher degree of integration can be realized. Further, in the magnetic memory element of the present invention, the power consumption of the magnetic memory can be reduced by the fact that the conductor layer is adjacent to the memory layer and the magnetic field generated by the conductor layer is concentrated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a magnetic memory element according to the present invention.

FIG. 2 illustrates a magnetic field generated by the film configuration of FIG.

FIG. 3 is a diagram showing a configuration example of a magnetic memory element according to the present invention.

FIG. 4 illustrates a magnetic field generated by the film configuration of FIG. 3;

FIG. 5 is a diagram showing a configuration example of a magnetic memory element according to the present invention.

FIG. 6 illustrates a magnetic field generated by the film configuration of FIG.

FIG. 7 is a diagram showing a configuration example of a magnetic memory element according to the present invention.

FIG. 8 is a diagram showing a configuration example of a magnetic memory using the MTJ element of the present invention.

FIG. 9 is a diagram showing a configuration example of a conventional MTJ element.

FIG. 10 is a diagram showing the operation principle of a conventional MTJ element used for a magnetic memory.

FIG. 11 is a diagram showing a configuration example of a conventional MTJ element.

[Explanation of symbols]

1 MTJ element 11, 61 Antiferromagnetic layer 12, 14, 16, 19, 21, 49, 62, 64, 7
1, 73, 74, 76 Ferromagnetic layer 13, 17, 27, 37, 47, 63 Insulating layer 15, 18, 28, 38, 48 Conducting layer 20, 82, 72, 75 Metal layer 51 Transistor 52 Bit line 53 Word Line 54 plate line

Continued on the front page (72) Inventor Kazuji Minami 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5E049 AA01 AA04 AA07 BA06 CB02 CC01 DB12 5F083 FZ10 GA05 GA09 JA60

Claims (7)

[Claims] At least a first magnetic layer, a non-magnetic layer, a second
The first or second magnetic memory element having a magnetic layer laminated thereon;
A magnetic memory element comprising a third magnetic layer provided on at least one side of a magnetic layer different from the non-magnetic layer lamination side via at least one conductor layer. 2. The magnetic memory device according to claim 1, wherein the magnitude of the magnetization of the third magnetic layer is substantially equal to the magnitude of the magnetization of the first or second magnetic layer in contact with the conductor layer. Magnetic memory element 3. The magnetic memory element according to claim 1, wherein a coercive force of a third magnetic layer is in contact with the first conductive layer.
Or a magnetic memory element having a coercive force smaller than that of a second magnetic layer 4. The magnetic memory device according to claim 1, wherein a second conductor layer is provided between said conductor layer and said third magnetic layer. 5. The magnetic memory device according to claim 1, wherein a second conductor layer is provided outside the first magnetic layer or the third magnetic layer, and the second conductor layer is further provided. A ferromagnetic layer is in contact with the side not facing the first magnetic layer or the third magnetic layer. 6. The magnetic memory device according to claim 1, wherein said non-magnetic layer sandwiched between said first magnetic layer and said second magnetic layer is an insulator. Memory element 7. A magnetic memory using the magnetic memory element according to claim 1.