JP2001284681A - Manufacturing method for magnetic memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a magnetic memory comprising a plurality of small magnetic memory elements of low power consumption wherein a magnetized state recorded in a memory layer is stable even if a pattern is micronized. SOLUTION: There are provided a process where a first conductor layer is so formed that magnetic memory elements are connected in only one direction on a plurality of magnetic memory elements in which a first magnetic layer, a non-magnetic layer, and a second magnetic layer are laminated; a process where, after an insulating layer is formed, a second conductor layer and a third magnetic layer are continuously formed; and a process where, after the third magnetic layer is shaped almost after the magnetic memory element, the second conductor layer is so worked as to connect the magnetic memory element only in the direction orthogonal to the first conductor layer.

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. 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 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.

[0004] 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 layer 42 and the ferromagnetic layer 44.

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 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 the memory layer detects whether the magnetization of the ferromagnetic layer 44 is parallel or antiparallel and the resistance of the MTJ element is different, reads out the data, and uses 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.

[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 comprising a plurality of magnetic memory elements in which the magnetization state recorded in the memory layer exists stably even when the pattern is miniaturized and the power consumption is small. It is intended to provide a manufacturing method.

[0012]

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, at least a step of sequentially forming a laminated film of a first magnetic layer, a non-magnetic layer, and a second magnetic layer on a substrate in order from the substrate side; Processing the stacked 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 formed on a substrate; Forming a first conductor layer and an insulating layer continuously on the magnetic memory element and on the insulating layer between the magnetic memory elements; and forming the first conductive layer and the first conductive layer so as to connect adjacent magnetic memory elements only in one direction. Before and after processing the conductor layer Forming an insulating layer so as to fill a space between the processed first conductive layers; and forming a second conductive layer and a third conductive layer on the processed first conductive layer and the insulating layer between the first conductive layers. Forming a magnetic layer continuously, and 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 second conductor layer so as to connect adjacent magnetic memory elements only in a direction orthogonal to the first conductor layer.

[0013]

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 antiferromagnetic layer 12, a ferromagnetic layer 13 (fixed layer), an insulating layer 14, and a ferromagnetic layer 15. (Free layer), conductor layer 1
6, an insulating layer 17, a conductor layer 18, and a ferromagnetic layer 19.
In the present embodiment, the fixed layer 13 is made of a ferromagnetic layer 20, a metal layer 21,
The ferromagnetic layer 22 is formed of a laminated film, and the thickness of the metal layer 21 is selected so that the ferromagnetic layer 20 and the ferromagnetic layer 22 are antiferromagnetically coupled. It is chosen to have approximately equal magnetization. The fixed layer 13 can 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 13 can be made substantially zero. Further, by using a material having a large anisotropic magnetic field for the ferromagnetic layers 20 and 22, a structure in which the antiferromagnetic layer 14 is omitted can be adopted.

The ferromagnetic layers 13, 15, and 19 are provided with uniaxial anisotropy in a direction parallel to the plane of the drawing, and the antiferromagnetic layer 12 and the ferromagnetic layer 13 are exchange-coupled. ing. In the magnetic memory element of the present embodiment, two states are created when the magnetizations of the ferromagnetic layer 22 and the ferromagnetic layer 15 forming the fixed layer 13 are parallel or antiparallel to each other. In this embodiment, the conductor layer 16 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 11 is a lower electrode, and the conductor layer 18 is a word line. Here, as shown in FIG. 1, a current flows through the conductor layer 16 perpendicularly to the plane of the paper and a conductor layer 18 flows parallel to the plane of the paper. 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. As described above, a combined magnetic field of the magnetic field H _B of the conductor layer 16 and the magnetic field H _W of the conductor layer 18 is applied to the positions of the ferromagnetic layers 17 and 19. FIG.
Since the directions of the combined magnetic field are different between the positions of the ferromagnetic layer 15 and the ferromagnetic layer 19 as shown in (a) and (b) of FIG. The layers 15, 19 are magnetized in different directions. Therefore, the magnetization of the ferromagnetic layer 15 is stabilized by the magnetic field generated by the magnetic poles generated at both ends of the ferromagnetic layer 19. Further, the ferromagnetic layer 1
By making the magnitude of the magnetization of the ferromagnetic layer 19 substantially equal to that of the ferromagnetic layer 5, there is no apparent magnetization to the outside, and the adjacent magnetic memory element is not affected. Furthermore, the ferromagnetic layers 15 and 19 have the conductor layer 16
Alternatively, since the direct contact is provided, sufficient magnetic field strength can be obtained even with a small current, and low power consumption of the magnetic memory element can be realized.

Since the two conductor layers 16 and 18 are located between the ferromagnetic layers 15 and 19, the positions of the ferromagnetic layers 11 and 19 are substantially antiparallel. Become. 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 reduced as compared with the case where the two conductor layers are not located between the ferromagnetic layers 15 and 19.

The material of the antiferromagnetic layer 12 is FeMn,
Alloys such as NiMn, PtMn, and IrMn can be used, and the material of the ferromagnetic layers 13, 15, 19 is Fe,
Co, Ni, or an alloy thereof can be used. The insulating layer 14 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 13, 15, 19 is desirably 10 ° or more, since 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 14 is 3 ° or more and 30 ° or less. This is because the ferromagnetic layer 13 and the ferromagnetic layer 15 may be electrically short-circuited when the thickness of the insulating layer 14 is 3 ° or less, and when the thickness of the insulating layer 14 is 30 ° or more, This is because the tunneling is difficult to occur, and the magnetoresistance ratio becomes small.

Next, a method of manufacturing the magnetic memory shown in FIG. 1 will be described with reference to FIGS. The figure is 1 for simplicity
FIG. 2 shows a cross-sectional view of one memory element as viewed from the side. Usually, the substrate on which the magnetic memory element is formed is formed by flattening an insulating layer on a semiconductor substrate on which a transistor for selecting the magnetic memory element is formed (not shown). In the first step, the conductor layer (lower electrode)
11, an antiferromagnetic layer 12, a ferromagnetic layer 13 (fixed layer), an insulating layer 14, and a ferromagnetic layer 15 (free layer) are successively formed (FIG. 3A). In this embodiment, the ferromagnetic layer 15 is composed of two ferromagnetic layers that are antiferromagnetically coupled with a metal layer interposed therebetween. However, it is possible to use only one ferromagnetic layer.
It is also possible to adopt a structure excluding the antiferromagnetic layer. 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-described 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. Third
In the step (3), processing is performed while leaving the conductor layer 11 so that each magnetic memory element is isolated (FIG. 3B). 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,
Resist 2 used as an etching mask in the third step
The insulating layer 23 is formed so as to fill the space between the isolated magnetic memory elements without peeling the insulating layer 4 away.
(A)｝. For the insulating layer 23, SiO ₂ or Al ₂ O ₃ can be used. By thus depositing the insulating layer 23 without removing the resist 24, the insulating layer 23 deposited on the magnetic memory element can be removed by lift-off (FIG. 4B). Therefore, a step of removing the insulating layer 23 on the magnetic memory element such as planarization becomes unnecessary. In the fifth step, the conductor layer 18 and the insulating layer 17 are continuously formed (FIG. 5A). In the sixth step, the conductor layer 18 and the insulating layer 1
A resist pattern is formed on 7 and the conductor layer 18 and the insulating layer 17 are processed so as to be connected to the magnetic memory element adjacent to the paper surface in the vertical direction {FIG. 5 (b)}. In the seventh step, the resist 2 used as the etching mask in the sixth step
An insulating layer 23 'is formed so as to fill the space between the formed wirings without peeling off 5 (FIG. 6A). By depositing the insulating layer 23 'without removing the resist 25, the insulating layer 23' deposited on the magnetic memory element can be removed by lift-off. In the eighth step, the conductor layer 18 and the magnetic layer 19 are continuously formed.
(B)｝. In the ninth step, the magnetic layer 19 is processed to have substantially the same shape as the magnetic memory element formed in the third step.
(A)｝. In the tenth step, the conductor layer 18 is processed so as to be connected only to the magnetic memory element adjacent in the direction parallel to the paper (FIG. 7B). By performing the processing of the conductor layer 18 last as described above, the etching of the insulating layer 23 (23 ') can be avoided. According to the manufacturing method described above, the magnetic memory element and the magnetic memory suitable for high density shown in FIG. 1 can be obtained.

Next, another method of manufacturing the magnetic memory shown in FIG. 1 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 23 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 23 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 first and second embodiments, the conductor layer 18 and the insulating layer 17 are formed continuously.
After forming only 8 and performing processing and flattening, the insulating layer 17, the conductor layer 18, and the magnetic layer 19 may be formed continuously.

In the configuration of the magnetic memory element, the magnetization of the ferromagnetic layer (fixed layer) 13 is fixed by exchange coupling with the antiferromagnetic layer 12, but a ferromagnetic material having a large coercive force is used as the fixed layer 13. Other means, such as use, can also be taken. Further, even if the ferromagnetic layer 13 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, the coercive force of the ferromagnetic layer 19 is set smaller than the coercive force of the ferromagnetic layer 15 so that the ferromagnetic layer 1 can be used for recording.
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 15, and can further reduce the current required for recording.

In any of these cases, it is possible to create 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.

In the above embodiment, the MTJ element has been described as an example.
A GMR element can be used if the conductor layer is insulated from the laminated portion of the ferromagnetic layer 13, the nonmagnetic layer 14, and the ferromagnetic layer 15.

[0028]

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 of manufacturing a magnetic memory element of the present invention, it is possible to provide a magnetic memory that consumes less power because the conductor layer is adjacent to the memory layer and the magnetization of the recording layer is easily rotated. Can be.

[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 in a ferromagnetic layer in 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 illustrates a manufacturing process of the magnetic memory device 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]

12, 41 Antiferromagnetic layer 13, 15, 19, 20, 22, 42, 44, 51, 5
3, 54, 56 Ferromagnetic layer 14, 17, 23, 23 ', 43 Insulating layer 11, 16, 18 Conductive layer 21, 52, 55 Metal layer 24, 25 Resist

Claims (1)

[Claims] 1. A method for manufacturing a magnetic memory comprising a plurality of magnetic memory elements in which at least a first magnetic layer, a nonmagnetic 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 magnetic layer, the non-magnetic layer, and the second magnetic layer in this order 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 formed in the first conductive layer, and a first conductive layer on the plurality of magnetic memory elements and on the insulating layer between the magnetic memory elements. A step of continuously forming an insulating layer, a step of processing the first conductor layer so as to connect adjacent magnetic memory elements only in one direction, and a step of forming a space between the processed first conductor layers. Forming an insulating layer to fill Forming a second conductive layer and a third magnetic layer continuously on the processed first conductive layer and on the insulating layer between the first conductive layers; and forming the third magnetic layer substantially as the magnetic memory element. A method of processing the second conductor layer so that adjacent magnetic memory elements are connected only in a direction orthogonal to the first conductor layer after processing into the same shape.