JP2001274480A - Manufacturing method of magnetic memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for magnetic memory comprising a plurality of magnetic memory elements, where a magnetized state recorded on a memory layer is present stably even if a pattern is micronized for less power consumption. SOLUTION: A manufacturing method is presented for the magnetic memory comprising a plurality of magnetic memory elements, where at least a first magnetic layer, a non-magnetic layer, and a second magnetic layer to be a recording layer are laminated. At least, a first magnetic layer to be a recording layer, a non magnetic layer and a second magnetic layer are succeedingly formed on a substrate as laminating films, and the laminating films are worked into forms of magnetic memory elements separated each other. An insulating layer is formed to fill the space between a plurality of magnetic memory elements on the substrate. A conductor layer and a third magnetic layer are succeedingly formed on the insulating layer on a plurality of magnetic memory elements as well as between the magnetic memory elements. The third magnetic layer is worked into a shape almost identical with the magnetic memory element. The conductor layer is so worked that adjoining magnetic memory elements are connected together only in one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic memory comprising a plurality of magnetic memory elements using the magnetoresistance effect.

[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.

[0003] A magnetic memory is a solid-state memory having 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 has a recorded content even if radiation is incident. It is more useful than a semiconductor memory because there is no risk of disappearing.

In particular, the MTJ element has a large resistance change rate, and is 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 41, a ferromagnetic layer 42, an insulating layer 43, and a ferromagnetic layer 44 stacked. Here, as the antiferromagnetic layer 41, FeMn, NiM
Alloys such as n, PtMn, and IrMn are used, and the ferromagnetic layers 42 and 44 are made of Fe, Co, Ni, or an alloy thereof. Various oxides and nitrides have been studied for the insulating layer 43, but it is known that the highest magnetoresistance (MR) ratio can be obtained with an Al ₂ O ₃ film.

[0005] In addition, there has been proposed an MTJ element having a configuration excluding the antiferromagnetic layer 41 and utilizing a coercive force difference between the ferromagnetic layers 42 and 44.

FIG. 10 shows the principle of operation when the MTJ element having the structure shown in FIG. 9 is used for a magnetic memory. The magnetizations of the ferromagnetic layer 42 and the ferromagnetic layer 44 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 42 is
1 is fixed substantially in one direction by exchange coupling, and holds the recording in the direction of magnetization of the ferromagnetic layer 44.

The ferromagnetic layer 44 serving as a memory layer detects whether the magnetization of the ferromagnetic layer 44 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 the magnetization of the ferromagnetic layer 44.

By the way, in the MTJ element having the above structure, the magnetization of the ferromagnetic layer 42 and the ferromagnetic layer 44 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, the ferromagnetic layer 42 (fixed layer) whose magnetization direction is fixed by being coupled to the antiferromagnetic layer 41 and the ferromagnetic layer 44 (free layer) that can freely rotate with respect to an external magnetic field.
Are laminated via an insulating layer 43. Further, both the ferromagnetic layer 42 and the ferromagnetic layer 44 are
Two ferromagnetic layers 5 antiferromagnetically coupled via 55
1, 53 and 54, 56. Therefore, it is possible to reduce the number of magnetic poles generated at the ends in both the free layer and the fixed layer.

[0009]

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 orthogonal arrangement, but when used in a magnetic memory element, it is usually used on a magnetic memory element. 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 comprising a plurality of magnetic memory elements which have a stable magnetization state recorded in a memory layer even when a pattern is miniaturized and consumes a small amount of power. It is intended to provide a manufacturing method.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and has a plurality of magnetic layers each having at least a first magnetic layer, a non-magnetic layer, and a second magnetic layer serving as a recording layer. A method of manufacturing a magnetic memory including a memory element, wherein the first magnetic layer serving as at least a recording layer on a substrate,
Forming a laminated film of the non-magnetic layer and the second magnetic layer continuously from the substrate side, processing the laminated film into a shape of a magnetic memory element separated from each other; Forming an insulating layer so as to fill a space between the plurality of magnetic memory elements, and forming a conductive layer and a third magnetic layer on the plurality of magnetic memory elements and on the insulating layer between the magnetic memory elements. After the step of continuously forming, and after processing the third magnetic layer into substantially the same shape as the magnetic memory element,
A method of manufacturing a magnetic memory, comprising a step of processing the conductor layer so as to connect adjacent magnetic memory elements only in one direction.

[0014]

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

FIG. 1 shows a magnetic memory element manufactured by the manufacturing method of the present invention. As shown in FIG. 1, the magnetic memory element 1 according to the present embodiment uses an MTJ element, and includes a conductor layer 11, an insulating layer 12, a conductor layer 13, an antiferromagnetic layer 14, a ferromagnetic layer 15 (fixed layer), It comprises an insulating layer 16, a ferromagnetic layer 17 (free layer), a conductor layer 18, and a ferromagnetic layer 19.

In this embodiment, the fixed layer 15 is made of a ferromagnetic layer 20,
It is composed of a laminated film of a metal layer 21 and a ferromagnetic layer 22, and the thickness of the metal layer 21 is selected so that the ferromagnetic layer 20 and the ferromagnetic layer 22 are antiferromagnetically coupled. Magnetic layer 22
Are chosen to have approximately equal magnetization. Fixed layer 1
5 can be formed of a single-layer ferromagnetic material, but by adopting such a laminated structure, the magnetic pole generated at the end of the fixed layer 15 can be made substantially zero.

By using a material having a large anisotropic magnetic field for the ferromagnetic layers 20 and 22, the antiferromagnetic layer 1
4 may be omitted.

The ferromagnetic layer 15, the ferromagnetic layer 17 and the ferromagnetic layer 19 are given uniaxial anisotropy in a direction parallel to the plane of the drawing, and the antiferromagnetic layer 14 and the ferromagnetic layer 15 are exchange-coupled. ing.

In the magnetic memory device of this embodiment, the fixed layer 1
5, the magnetizations of the ferromagnetic layer 22 and the ferromagnetic layer 17 are parallel or antiparallel to each other, and two states are created.

In this embodiment, the conductor layer 18 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 13 is a lower electrode,
The conductor layer 11 is a word line.

Here, as shown in FIG. 1, a current flows through the conductor layer 18 perpendicularly to the plane of the drawing, and a current flows through the conductive layer 11 parallel to the plane of the drawing. FIG. 2 shows a magnetic field generated at the positions of the ferromagnetic layer 17 and the ferromagnetic layer 19 by two currents when viewed from a direction perpendicular to the film surface. Thus, at the positions of the ferromagnetic layer 17 {FIG. 2 (b)} and the ferromagnetic layer 19 {FIG. 2 (a)}, the combined magnetic field of the magnetic field H _B by the conductor layer 18 and the magnetic field H _W by the conductor layer 11 is shown. Applied. FIG. 2 (a) and FIG.
As shown in (b), since the directions of the combined magnetic field are different at the positions of the ferromagnetic layer 17 and the ferromagnetic layer 19, the ferromagnetic layers 17 and 19 provided with uniaxial anisotropy in the horizontal direction of the paper are different from each other. It is magnetized in the direction. Therefore, the magnetization of the ferromagnetic layer 17 is stabilized by the magnetic field generated by the magnetic poles generated at both ends of the ferromagnetic layer 19.

Further, by making the magnitudes of the magnetizations of the ferromagnetic layer 17 and the ferromagnetic layer 19 substantially equal to each other, there is no apparent magnetization to the outside, which may affect adjacent magnetic memory elements. Disappears. Furthermore, the ferromagnetic layer 1
Since the conductor layer 18 is in direct contact with the ferromagnetic layer 7 and the ferromagnetic layer 19, 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.

The material of the antiferromagnetic layer 14 is FeMn,
Alloys such as NiMn, PtMn, and IrMn can be used, and the material of the ferromagnetic layers 15, 17, and 19 is Fe,
Co, Ni, or an alloy thereof can be used. The insulating layer 16 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, a diamond-like carbon (DLC). It may be an insulating film such as a film.

The thickness of the ferromagnetic layers 15, 17, and 19 is desirably 10 ° or more because if the thickness is too small, the ferromagnetic material becomes superparamagnetic due to the influence of thermal energy. Also,
It is preferable that the thickness of the insulating layer 16 is 3 ° or more and 30 ° or less. This is because when the thickness of the insulating layer 16 is 3 ° or less, the ferromagnetic layer 15 and the ferromagnetic layer 17 may be electrically short-circuited, and when the thickness of the insulating layer 16 is 30 ° or more, This is because the tunneling is difficult to occur, and the magnetoresistance ratio becomes small.

Next, a first method of manufacturing the magnetic memory shown in FIG. 1 will be described with reference to FIGS. The figure shows a cross-sectional view of one memory element for simplification.

Usually, the substrate on which the magnetic memory element is formed is
An insulating layer is further formed and planarized on a semiconductor substrate on which a transistor for selecting a magnetic memory element is formed. The word line may be arranged below the magnetic memory element as shown in FIG. 1, or may be arranged above (not shown).

In the first step, the conductor layer (lower electrode) 13,
Antiferromagnetic layer 14, ferromagnetic layer 15 (fixed layer), insulating layer 1
6. Continuous formation of ferromagnetic layer 17 (free layer) {FIG.
(A)｝. In this embodiment, the ferromagnetic layer 15 is composed of two ferromagnetic layers that are antiferromagnetically coupled with a metal layer interposed therebetween. However, the ferromagnetic layer 15 can be composed of only one ferromagnetic layer. A structure without the ferromagnetic layer is also possible.
In any case, it is possible to manufacture a magnetic memory element using the manufacturing method according to the present invention. For forming each layer, a general film forming method such as a sputtering method or a vapor deposition method can be used.

In the second step, the above-mentioned laminated film is processed into a shape of a lower electrode. As a processing method, first, a resist pattern is formed using photolithography, and processing is performed into a desired shape by ion beam etching or the like (not shown). In the steps described below, a similar processing method can be used for processing the element shape.

In the third step, processing is performed while leaving the conductor layer 13 so that each magnetic memory element is isolated.
(B)｝. In the steps up to this point, isolated magnetic memory elements positioned at intervals determined by the wiring rule are formed.

In the fourth step, the insulating layer 24 is formed so as to fill the space between the isolated magnetic memory elements without removing the resist 23 used as the etching mask in the third step {FIG. (A)｝. The insulating layer 24 is made of SiO
₂ or Al ₂ O ₃ can be used. By depositing the insulating layer 24 without removing the resist 23 in this manner,
The insulating layer 24 deposited on the magnetic memory element can be removed by lift-off (FIG. 4B). for that reason,
The step of removing the insulating layer 24 on the magnetic memory element, such as planarization, becomes unnecessary.

In the fifth step, the second conductor layer 18 and the third
(FIG. 5A).

In the sixth step, the third magnetic layer 19 is
(FIG. 5 (b)).

In the seventh step, the second conductor layer 18 is processed so as to be connected only in the depth direction of the drawing (FIG. 6).
By performing the processing of the conductor layer 18 last, the insulating layer 22 can be prevented from being etched.

By the above manufacturing method, the magnetic memory element and the magnetic memory suitable for high density shown in FIG. 1 can be obtained.

In this embodiment, the conductor layer 11 serving as a word line is disposed below the memory element (substrate side). However, even if the conductor layer 11 is disposed above the memory element, the density can be increased by the manufacturing method of this embodiment. A magnetic memory element and a magnetic memory suitable for the present invention can be obtained.

Further, as shown in FIG. 7, it is also possible to manufacture a structure in which the ferromagnetic layer 31 having a high magnetic permeability is in contact with the side of the conductor layer 11 serving as a word line which does not face the memory element. . In this structure, a current flows through the conductive layer 11 during recording to generate a magnetic field. However, since the ferromagnetic layer 31 has a high magnetic permeability, the magnetic field on the ferromagnetic layer 31 side of the conductive layer 11 is concentrated on the ferromagnetic layer 31. I do. As a result, the magnetic field of the conductor layer 11 on the side opposite to the ferromagnetic layer 31 increases, and even when the same current flows, the ferromagnetic layer 17 and the ferromagnetic layer 17 serving as the recording layer are compared with the case without the ferromagnetic layer 31. The magnetic field strength at position 19 increases. Therefore, the power consumption of the magnetic memory can be reduced as compared with the case where the ferromagnetic layer 31 is not provided.

The ferromagnetic layer 31 is made of a NiFe alloy, CoZr
High-permeability alloys such as Nb-based amorphous alloys and FeAlSi-based alloys can be used. The ferromagnetic layer 31 is the conductor layer 11
Therefore, in the subsequent steps, the manufacturing method shown in the first embodiment can be used as it is.

As described above, the method of manufacturing a magnetic memory device according to the present invention makes it possible to obtain a magnetic memory device and a magnetic memory which are suitable for high density and which consume low power as shown in FIG.

Next, a second manufacturing method of the present invention will be described with reference to FIG.

This embodiment is the same as the manufacturing method according to the first embodiment up to the third step of processing so that the magnetic memory element is isolated. In the fourth step, the insulating layer 24 is formed so as to fill the space between the isolated magnetic memory elements by removing the resist (FIG. 8A). In the fifth step, the insulating layer 24 on the magnetic memory element is removed and planarized by machining such as CMP (FIG. 8B). Alternatively, the insulating layer on the magnetic memory element can be removed by flattening unevenness generated after the formation of the insulating layer with a resist and etching back the whole. By performing the subsequent steps in the same manner as in the first embodiment, the magnetic memory element and the magnetic memory suitable for high density shown in FIG. 1 can be obtained.

In the configuration of the magnetic memory element, the magnetization of the ferromagnetic layer (fixed layer) 15 is fixed by exchange coupling with the antiferromagnetic layer 14, but a ferromagnetic material having a large coercive force is used as the fixed layer 15. Other means, such as use, can also be taken. Further, even if the ferromagnetic layer 15 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.

Further, as another configuration of the magnetic memory element, by setting the coercive force of the ferromagnetic layer 19 to be smaller than the coercive force of the ferromagnetic layer 17, the
9 can be reversed first. This allows
The magnetic poles generated at both ends of the ferromagnetic layer 19 generate a magnetic field in a direction that promotes the reversal of the magnetization direction of the ferromagnetic layer 17, and can further reduce the current required for recording.

In any of these cases, it is possible to produce a magnetic memory element and a magnetic memory using the manufacturing method according to the present invention.

In the above-described embodiment, only the magnetic memory element is shown.
Obviously, a protective layer and an adhesion layer are required.

Further, in the above embodiment, the MTJ element has been described as an example, but the antiferromagnetic layer 14 which is a memory element part,
A GMR element can also be used if the conductor layer is insulated from the laminated portion of the ferromagnetic layer 15, the nonmagnetic layer 16, and the ferromagnetic layer 17.

[0046]

As described above, according to the method of manufacturing a magnetic memory element of the present invention, the magnetic memory capable of stabilizing the magnetization of the recording layer and reducing the influence between adjacent magnetic memory elements can be reduced. An element is obtained. Therefore, a stable magnetization state can be maintained even when the pattern is miniaturized, and a magnetic memory with a higher degree of integration can be realized. Further, according to the method for manufacturing a magnetic memory element of the present invention, a magnetic memory with low power consumption is provided by the fact that the conductor layer is adjacent to the memory layer and the magnetic field generated by the conductor layer is concentrated on the recording layer. can do.

[Brief description of the drawings]

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

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

FIG. 3 illustrates a manufacturing process of the magnetic memory device according to the present invention.

FIG. 4 illustrates a manufacturing process of the magnetic memory device according to the present invention.

FIG. 5 illustrates a manufacturing process of the magnetic memory device according to the present invention.

FIG. 6 illustrates a manufacturing process of the magnetic memory device according to the present invention.

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

FIG. 8 shows a manufacturing process of the magnetic memory device according to 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]

13, 41 Antiferromagnetic layer 15, 17, 19, 20, 22, 42, 44, 51, 5
3, 54, 56 Ferromagnetic layer 12, 16, 24, 43 Insulating layer 11, 13, 18 Conductive layer 21, 52, 55 Metal layer 23 Resist

Claims (1)

[Claims] 1. A method of manufacturing a magnetic memory comprising a plurality of magnetic memory elements in which at least a first magnetic layer, a non-magnetic layer, and a second magnetic layer serving as a recording layer are stacked, wherein at least the first magnetic layer is formed on a substrate. Forming a laminated film of a layer, the non-magnetic layer, and the second magnetic layer sequentially from the substrate side; processing the laminated film into a shape of a magnetic memory element separated from each other; Forming an insulating layer to fill a space between the formed plurality of magnetic memory elements; and forming a conductive layer and a third magnetic layer on the plurality of magnetic memory elements and on the insulating layer between the magnetic memory elements. Forming a layer continuously; and processing the third magnetic layer into a substantially same shape as the magnetic memory element, and then processing the conductor layer so that adjacent magnetic memory elements are connected only in one direction. It is characterized by consisting of Method of manufacturing a magnetic memory