阅读说明：本技术 磁畴壁移动元件及磁存储阵列 (Magnetic domain wall moving element and magnetic memory array ) 是由 芦田拓也 柴田龙雄 于 2021-05-24 设计创作，主要内容包括：本发明提供一种可靠性高的磁畴壁移动元件及磁存储阵列。本实施方式的磁畴壁移动元件从靠近基板的一侧起依次层叠有第一铁磁性层、非磁性层、第二铁磁性层,从层叠方向俯视,在沿着与所述第一铁磁性层延伸的第一方向正交的第二方向切断的切断面上,所述第一铁磁性层的所述第二方向的最短宽度比所述非磁性层的所述第二方向的宽度短。(The invention provides a magnetic domain wall moving element with high reliability and a magnetic storage array. In the domain wall moving element of the present embodiment, a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer are stacked in this order from a side close to a substrate, and a shortest width in a second direction of the first ferromagnetic layer is shorter than a width in the second direction of the nonmagnetic layer on a cut surface cut along the second direction orthogonal to the first direction in which the first ferromagnetic layer extends when viewed from the stacking direction.)

1. A magnetic domain wall moving element characterized in that,

a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer are laminated in this order from the side close to the substrate,

a cross-sectional surface cut along a second direction orthogonal to the first direction in which the first ferromagnetic layer extends when viewed from the stacking direction,

the shortest width of the second direction of the first ferromagnetic layer is shorter than the width of the second direction of the nonmagnetic layer.

2. The magnetic domain wall moving element of claim 1,

in a cross section along the stacking direction and the second direction, a side surface of the first ferromagnetic layer is inclined with respect to the stacking direction.

3. The magnetic domain wall moving element of claim 2,

a side surface of the first ferromagnetic layer has a first inclined surface and a second inclined surface on a cross section along the stacking direction and the second direction,

the first inclined surface is inclined from a lower end of the first ferromagnetic layer on a side close to the substrate toward a center of the first ferromagnetic layer in the second direction,

the second inclined surface is inclined from an upper end of the first ferromagnetic layer on a side away from the substrate toward a center of the first ferromagnetic layer in the second direction.

4. The domain wall moving element of any one of claims 1 to 3,

the width of the first ferromagnetic layer in the second direction on the first surface on the side of the nonmagnetic layer is shorter than the width of the nonmagnetic layer in the second direction.

5. The magnetic domain wall moving element of any one of claims 1 to 4,

the position where the width of the first ferromagnetic layer in the second direction is shortest is located closer to the nonmagnetic layer side than the center of the first ferromagnetic layer in the stacking direction.

6. The magnetic domain wall moving element of any one of claims 1 to 5,

the longest width of the second direction of the first ferromagnetic layer is shorter than the width of the second direction of the nonmagnetic layer.

7. The magnetic domain wall moving element of any one of claims 1 to 5,

the width of the second direction of a second face of the first ferromagnetic layer on a side away from the nonmagnetic layer is longer than the width of the second direction of the nonmagnetic layer.

8. The magnetic domain wall moving element of any one of claims 1 to 7,

the thickness of the nonmagnetic layer isThe above.

9. The magnetic domain wall moving element of any one of claims 1 to 8,

the milling rate of the non-magnetic layer is slower than the milling rate of the first ferromagnetic layer.

10. The magnetic domain wall moving element of any one of claims 1 to 9,

a base layer is further provided on the first ferromagnetic layer on the side opposite to the nonmagnetic layer,

the substrate layer mills at a slower rate than the first ferromagnetic layer.

11. The magnetic domain wall moving element of claim 10,

the first ferromagnetic layer contains an element constituting the base layer,

with respect to the abundance of the element, a first region located closer to the base layer side than a position where the width of the first ferromagnetic layer in the second direction is shortest in the stacking direction is denser than a second region located closer to the nonmagnetic layer side than a position where the width of the first ferromagnetic layer in the second direction is shortest in the stacking direction.

12. The domain wall moving element of claim 10 or 11,

having a first conductive portion and a second conductive portion that sandwich the nonmagnetic layer in the first direction and are electrically connected to the first ferromagnetic layer via the base layer,

a width of each of the first conductive portion and the second conductive portion in the second direction is wider than a width of the first ferromagnetic layer in the second direction,

the base layer has a milling rate that is slower than milling rates of the first and second conductive portions.

13. The domain wall moving element of any one of claims 1 to 12,

the second ferromagnetic layer is further provided with a metal layer different from the second ferromagnetic layer on a side in the second direction.

14. A magnetic memory array having a plurality of domain wall-moving elements as claimed in any one of claims 1 to 13.

Technical Field

The present invention relates to a magnetic domain wall moving element and a magnetic memory array.

Background

Attention is being paid to the next-generation nonvolatile memory that replaces flash memories and the like, which are the most visible in miniaturization. As next-generation nonvolatile memories, for example, MRAM (Magnetoresistive Random Access Memory), ReRAM (resistive Random Access Memory), PCRAM (Phase Change Random Access Memory), and the like are known.

MRAM uses a change in resistance value due to a change in the direction of magnetization for data storage. The data storage is respectively carried by the magnetoresistive variable elements constituting the MRAM. For example, patent document 1 describes a 3-terminal type magnetoresistive element in which a write current and a read current are routed separately.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 6275806

Disclosure of Invention

Technical problem to be solved by the invention

In some cases, a process called thinning (sliming) is performed when the magnetoresistance effect element is miniaturized. The thinning is a treatment of irradiating the side surface of the magnetoresistance effect element with an ion beam to reduce the plan view area of the magnetoresistance effect element. However, if the ion beam is irradiated to the exposed metal surface, a part of the metal may scatter and adhere to the sidewall of the magnetoresistance effect element again. The impurities adhering to the side wall of the magnetoresistance effect element deteriorate the magnetic characteristics of the ferromagnetic body constituting the magnetoresistance effect element. In addition, the attached impurities also cause leakage of the magnetoresistive element. The impurities attached to the side walls of the magnetoresistance effect element may reduce the reliability of the magnetoresistance effect element.

The present invention has been made in view of the above problems, and provides a magnetoresistive element and a magnetic memory array having high reliability.

Means for solving the problems

(1) In the domain wall propagating device of the first aspect, a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer are sequentially stacked from a side close to a substrate, and a shortest width in a second direction of the first ferromagnetic layer is shorter than a width in the second direction of the nonmagnetic layer on a cut surface cut along the second direction orthogonal to the first direction in which the first ferromagnetic layer extends when viewed from a stacking direction.

(2) In the domain wall propagating device according to the above aspect, a side surface of the first ferromagnetic layer may be inclined with respect to the stacking direction at a cut surface along the stacking direction and the second direction.

(3) In the domain wall propagating device according to the above aspect, a side surface of the first ferromagnetic layer may include a first inclined surface and a second inclined surface, the first inclined surface being inclined from a lower end of the first ferromagnetic layer on a side closer to the substrate toward a center of the first ferromagnetic layer in the second direction, and the second inclined surface being inclined from an upper end of the first ferromagnetic layer on a side farther from the substrate toward the center of the first ferromagnetic layer in the second direction.

(4) In the domain wall propagating device according to the above aspect, a width of the first ferromagnetic layer in the second direction on the first surface on the nonmagnetic layer side may be shorter than a width of the nonmagnetic layer in the second direction.

(5) In the domain wall propagating device according to the above aspect, a position at which the width of the first ferromagnetic layer in the second direction becomes the shortest may be located closer to the nonmagnetic layer side than a center of the first ferromagnetic layer in the stacking direction.

(6) In the domain wall moving element according to the above aspect, the longest width of the first ferromagnetic layer in the second direction may be shorter than the width of the nonmagnetic layer in the second direction.

(7) In the domain wall propagating device according to the above aspect, a width of a second surface of the first ferromagnetic layer on a side away from the nonmagnetic layer in the second direction may be longer than a width of the nonmagnetic layer in the second direction.

(8) In the domain wall propagating device of the above aspect, the nonmagnetic layer may have a thicknessThe above.

(9) In the domain wall moving element in the above-described manner, the milling rate of the nonmagnetic layer may be slower than that of the first ferromagnetic layer.

(10) In the domain wall propagating device according to the above aspect, a base layer may be further provided on the first ferromagnetic layer on the side opposite to the nonmagnetic layer, and the base layer may be milled at a slower rate than the first ferromagnetic layer.

(11) The first ferromagnetic layer of the domain wall moving element of the above-described aspect may include an element constituting the underlayer, and a first region located closer to the underlayer side than a position where the width in the second direction of the first ferromagnetic layer is shortest in the stacking direction may be thicker than a second region located closer to the nonmagnetic layer side than a position where the width in the second direction of the first ferromagnetic layer is shortest in the stacking direction, with respect to the abundance of the element.

(12) The domain wall propagating element according to the above aspect may have a first conductive portion and a second conductive portion that sandwich the nonmagnetic layer in the first direction and are electrically connected to the first ferromagnetic layer via the base layer, wherein the first conductive portion and the second conductive portion each have a width in the second direction that is wider than a width in the second direction of the first ferromagnetic layer, and the base layer may have a milling rate that is slower than milling rates of the first conductive portion and the second conductive portion.

(13) The domain wall propagating element according to the above aspect may further include a metal layer different from the second ferromagnetic layer on the side of the second ferromagnetic layer in the second direction.

(14) A magnetic memory array of the second embodiment has a plurality of domain wall-moving elements of the above-described embodiment.

Effects of the invention

The domain wall motion element and the magnetic memory array according to the above-described embodiments have excellent reliability.

Drawings

Fig. 1 is a structural diagram of a magnetic memory array of the first embodiment.

FIG. 2 is a cross-sectional view of a feature of the magnetic memory array of the first embodiment.

Fig. 3 is an xz sectional view of the magnetic domain wall moving element of the first embodiment.

Fig. 4 is a top view of a magnetic domain wall moving element of the first embodiment.

Fig. 5 is a yz sectional view at the center of the x direction of the magnetic domain wall moving element of the first embodiment.

Fig. 6 is a yz sectional view in the first conductive part of the magnetic domain wall moving element of the first embodiment.

Fig. 7 is a schematic view for explaining thinning when manufacturing the magnetic domain wall moving element of the first embodiment.

Fig. 8 is a yz cross-sectional view at the center in the x direction of the magnetic domain wall moving element of the first modification.

Fig. 9 is a yz cross-sectional view at the center in the x direction of the magnetic domain wall moving element of the second modification.

Fig. 10 is a yz cross-sectional view at the center in the x direction of a magnetic domain wall moving element of a third modification.

Fig. 11 is an xz sectional view of the magnetic domain wall moving element of the first embodiment.

Fig. 12 is a yz sectional view at the center in the x direction of the magnetic domain wall moving element of the first embodiment.

Description of the symbols

10. 70 … … first ferromagnetic layer

10a, 70a … … first side

10b, 70b … … second side

20. 80 … … second ferromagnetic layer

30 … … non-magnetic layer

40 … … base layer

51 … … first conductive part

52 … … second conductive part

60 … … metal layer

100. 101, 102, 103, 110 … … magnetic domain wall moving element

200 … … magnetic memory array

L10max … … longest Width

L10min … … shortest Width

L30 … … width

R1 … … first region

R2 … … second region

s1 … … first inclined plane

s2 … … second inclined plane

s3 … … inclined plane

Detailed Description

Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings as appropriate. In the drawings used in the following description, in order to make the features of the present invention easily understood, the portions that are to be the features may be enlarged at low cost, and the dimensional ratios of the respective components may be different from those in reality. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to these examples, and can be implemented by appropriately changing the materials, dimensions, and the like within a range in which the effects of the present invention are achieved.

First, the direction is defined. The x direction and the y direction are directions substantially parallel to one surface of a substrate Sub (see fig. 2) described later. The x direction is a direction in which the first ferromagnetic layer 10 described later extends, and is a direction from the first conductive portion 51 described later toward the second conductive portion 52. The y direction is a direction orthogonal to the x direction. The z direction is a direction from the substrate Sub described later toward the domain wall moving element 100. The z direction is an example of the stacking direction. In the present specification, the phrase "extending in the x direction" means that, for example, the dimension in the x direction is larger than the smallest dimension among the dimensions in the x direction, the y direction, and the Z direction. The same applies to the case of extension in other directions.

[ first embodiment ]

Fig. 1 is a structural diagram of a magnetic memory array of the first embodiment. The magnetic memory array 200 includes a plurality of domain wall-moving elements 100, a plurality of first wires Wp1 to Wpn, a plurality of second wires Cm1 to Cmn, a plurality of third wires Rp1 to Rpn, a plurality of first switching elements 110, a plurality of second switching elements 120, and a plurality of third switching elements 130. The magnetic memory array 200 can be used for a magnetic memory, a multiplier accumulator (multiplier accumulator), or a neuromorphic (neuromorphic) device, for example.

First, second, and third wirings

The first wirings Wp1 to Wpn are write wirings. The first wires Wp1 to Wpn electrically connect the power supply and the one or more domain wall-moving elements 100. A power supply is connected to one end of the magnetic storage array 200 in use.

The second wirings Cm1 to Cm are common wirings. The common wiring is a wiring that can be used for both writing and reading of data. The second wirings Cm1 to Cm electrically connect the reference potential and the one or more domain wall moving elements 100. The reference potential is, for example, ground. The second wires Cm1 to Cm may be provided in each of the domain wall moving elements 100, or may be provided over the domain wall moving elements 100.

The third wirings Rp1 to Rp Rpn are readout wirings. The third wires Rp1 to Rp Rpn electrically connect the power supply and one or more domain wall-moving elements 100. A power supply is connected to one end of the magnetic storage array 200 in use.

First, second, and third switching elements

The first, second, and third switching elements 110, 120, and 130 shown in fig. 1 are connected to each of the plurality of domain wall-moving elements 100. The first switching element 110 is connected between each of the domain wall-moving elements 100 and the first wires Wp 1-Wpn. The second switching element 120 is connected between each of the domain wall-moving elements 100 and the second wires Cm1 to Cm. The third switching element 130 is connected between each of the domain wall moving elements 100 and the third wires Rp1 to Rp Rpn.

When the first switching element 110 and the second switching element 120 are turned ON, the write current flows between the first wires Wp1 to Wpn and the second wires Cm1 to Cm connected to the predetermined domain wall moving element 100. When the first switching element 110 and the third switching element 130 are turned ON, the readout current flows between the second wires Cm1 to Cmn and the third wires Rp1 to Rpn connected to the predetermined domain wall moving element 100.

The first switching element 110, the second switching element 120, and the third switching element 130 are elements that control the flow of current. The first switching element 110, the second switching element 120, and the third switching element 130 are, for example, transistors, elements that utilize phase change of a crystal layer such as an Ovonic Threshold Switch (OTS), elements that utilize change of a band structure such as a metal-insulator transition (MIT) Switch, elements that utilize a breakdown voltage such as a Zener Diode and an avalanche breakdown Diode, and elements whose conductivity changes with a change in atomic position.

Any one of the first switching element 110, the second switching element 120, and the third switching element 130 may also be shared by the domain wall moving elements 100 connected to the same wire. For example, in the case of sharing the first switching element 110, one first switching element 110 is provided upstream of the first wirings Wp1 to Wpn. For example, in the case of sharing the second switching element 120, one second switching element 120 is provided upstream of the second wirings Cm1 to Cm. For example, in the case of sharing the third switching element 130, one third switching element 130 is provided upstream of the third wirings Rp1 to Rp Rpn.

FIG. 2 is a cross-sectional view of a feature of the magnetic memory array 200 of the first embodiment. Fig. 2 is a cross section of one domain wall moving element 100 in fig. 1 cut in an xz plane passing through the center of the width of the first ferromagnetic layer 10 in the y direction.

The first switching element 110 and the second switching element 120 shown in fig. 2 are transistors Tr. The transistor Tr includes a gate electrode G, a gate insulating film GI, and a source region S and a drain region D formed on the substrate Sub. The substrate Sub is, for example, a semiconductor substrate. The third switching element 130 is electrically connected to the electrode E, and is located in the depth direction (+ y direction) of the paper, for example.

Each of the transistors Tr and the domain wall moving element 100 are electrically connected via wires W. The wiring W includes a material having conductivity. The wiring W extends in the z direction, for example. The wiring W is, for example, a through hole wiring formed In an opening of the insulating layer In.

The domain wall moving element 100 and the transistor Tr are electrically separated from each other by an insulating layer In, excluding the wire W. The insulating layer In is an insulating layer for insulating between wirings of the multilayer wiring or between elements. The insulating layer In is, for example, silicon oxide (SiO)_x) Silicon nitride (SiN)_x) Silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al)₂O₃) Zirconium oxide (ZrO)_x) And the like.

Magnetic domain wall moving element "

Fig. 3 is a sectional view of the domain wall moving element 100 cut off in the xz plane passing through the center of the y direction of the first ferromagnetic layer 10. Fig. 4 is a diagram of a magnetic domain wall moving element 100 viewed from the z direction. Fig. 5 is a cross-sectional view in which the domain wall moving element 100 is cut off in the yz plane passing through the center of the x direction of the domain wall moving element 100. Fig. 5 is a cross-section of the magnetic domain wall moving element 100 cut along the a-a line of fig. 4. Fig. 6 is a cross-sectional view in which the domain wall moving element 100 is cut through the yz plane of the first conductive part 51 of the domain wall moving element 100. Fig. 6 is a cross-section of the magnetic domain wall moving element 100 cut along the B-B line of fig. 4.

The domain wall moving element 100 has, for example, a first ferromagnetic layer 10, a second ferromagnetic layer 20, a nonmagnetic layer 30, a substrate layer 40, a first conductive portion 51, and a second conductive portion 52. For example, the first ferromagnetic layer 10, the nonmagnetic layer 30, and the second ferromagnetic layer 20 are laminated in this order from the side close to the substrate Sub. Other layers may be interposed between the first ferromagnetic layer 10 and the nonmagnetic layer 30 and between the nonmagnetic layer 30 and the second ferromagnetic layer 20. When writing data to the domain wall moving element 100, a write current is caused to flow through the first ferromagnetic layer 10 between the first conductive portion 51 and the second conductive portion 52. When reading data from the domain wall moving element 100, a read current is passed between the first conductive portion 51 or the second conductive portion 52 and the second ferromagnetic layer 20.

First ferromagnetic layer "

The first ferromagnetic layer 10 extends in the x direction. The first ferromagnetic layer 10 is supplied with a write current. The first ferromagnetic layer 10 is, for example, a rectangle having a major axis in the x direction and a minor axis in the y direction when viewed from the z direction. The first ferromagnetic layer 10 is located closer to the substrate Sub side than the second ferromagnetic layer 20, for example. The write current flows along the first ferromagnetic layer 10 from the first conductive portion 51 toward the second conductive portion 52 or from the second conductive portion 52 toward the first conductive portion 51.

The first ferromagnetic layer 10 is a layer capable of magnetically storing information by a change in internal magnetic state. The first ferromagnetic layer 10 is sometimes referred to as a magnetic storage layer or a domain wall moving layer.

As shown in fig. 3, the first ferromagnetic layer 10 has, for example, magnetization fixed regions 11, 12 and a domain wall moving region 13. The domain wall moving region 13 is sandwiched by the two magnetization fixed regions 11 and 12, for example, in the x direction.

The magnetization fixed region 11 is a region overlapping with the first conductive portion 51 of the first ferromagnetic layer 10 when viewed from the z direction. The magnetization fixed region 12 is a region overlapping with the second conductive portion 52 of the first ferromagnetic layer 10 when viewed from the z direction. Magnetization M of the magnetization-fixed regions 11, 12₁₁、M₁₂And the magnetization M of the domain wall moving region 13_13A、M_13BIn contrast, magnetization inversion is not easily caused even if the magnetization M of the domain wall moving region 13 is applied_13A、M_13BThe external force of the threshold value of the reversal does not magnetize and reverse either. Thus, the magnetization M of the magnetization fixed regions 11, 12₁₁、M₁₂It can be said that the magnetization M with respect to the domain wall moving region 13_13A、M_13BAnd (4) fixing.

Magnetization M of the magnetization fixed region 11₁₁And magnetization M of the magnetization fixed region 12₁₂Oriented in different directions. Magnetization M of the magnetization fixed region 11₁₁And magnetization M of the magnetization fixed region 12₁₂For example in the opposite direction. Magnetization M of the magnetization fixed region 11₁₁For example, oriented in the + z direction, magnetizes the magnetization M of the fixed region 12₁₂For example, oriented in the-z direction.

The domain wall moving region 13 is composed of a first magnetic region 13A and a second magnetic region 13B. The first magnetic region 13A is adjacent to the magnetization fixed region 11. Magnetization M of first magnetic region 13A_13AMagnetization M of the magnetized fixed region 11₁₁E.g. along the magnetization M associated with the magnetization-fixed region 11₁₁Oriented in the same direction. The second magnetic region 13B is adjacent to the magnetization fixed region 12. Magnetization M of second magnetic region 13B_13BMagnetization M of the magnetized fixed region 12₁₂E.g. along the magnetization M associated with the magnetization-fixed region 12₁₂Oriented in the same direction. Thus, the magnetization M of the first magnetic region 13A_13AAnd magnetization M of second magnetic region 13B_13BOriented in different directions. Of the first magnetic region 13AMagnetization M_13AAnd magnetization M of second magnetic region 13B_13BFor example in the opposite direction.

The boundary of the first magnetic region 13A and the second magnetic region 13B is a magnetic domain wall DW. The magnetic domain wall DW moves within the magnetic domain wall moving region 13. The magnetic domain wall DW does not in principle encroach into the magnetization pinned regions 11, 12.

In the domain wall moving region 13, the domain wall DW is moved by passing a writing current in the x direction of the domain wall moving region 13. For example, if a writing current (e.g., a current pulse) in the + x direction is applied to the domain wall moving region 13, electrons flow in the-x direction opposite to the current, and thus, the domain wall DW moves in the-x direction. When a current flows from first magnetic region 13A toward second magnetic region 13B, the spin-polarized electrons in second magnetic region 13B cause magnetization M of first magnetic region 13A_13AMagnetization reversal is performed. Magnetization M by first magnetic region 13A_13AMagnetization inversion is performed so that the magnetic domain wall DW moves in the-x direction. In the domain wall moving region 13, if a domain wall moves, the ratio of the first magnetic region 13A and the second magnetic region 13B changes.

In the domain wall moving region 13, if the domain wall DW moves, the ratio of the first magnetic region 13A and the second magnetic region 13B changes, and the resistance of the domain wall moving element 100 changes according to the ratio of the first magnetic region 13A and the second magnetic region 13B. In addition, if the position of the domain wall DW is moved in stages, the resistance value of the domain wall moving element 100 changes in stages, and if the position of the domain wall DW is moved continuously, the resistance value of the domain wall moving element 100 changes continuously. The domain wall moving element 100 in which the resistance value is changed stepwise is suitable for processing multi-valued data. The domain wall moving element 100, in which the resistance value is continuously varied, is adapted to process analog data.

As shown in fig. 5 and 6, the shortest width L10min in the y direction of the first ferromagnetic layer 10 is shorter than the width L30 in the y direction of the nonmagnetic layer 30. The y-direction width L30 of the nonmagnetic layer 30 is an average value of the y-direction widths, and for example, when the y-direction width changes depending on the z-direction position, it means the average value thereof.

The width of the first ferromagnetic layer 10 in the y direction shown in fig. 5 and 6 differs depending on the position in the z direction. For example, the first surface 10a and the second surface 10b of the first ferromagnetic layer 10 have different widths in the y direction. The first surface 10a is a surface of the first ferromagnetic layer 10 on the nonmagnetic layer 30 side. The second surface 10b is a surface of the first ferromagnetic layer 10 opposite to the first surface 10 a.

The width of the first surface 10a in the y direction shown in fig. 5 and 6 is the same as the width L30 of the nonmagnetic layer 30 in the y direction. The width of the first ferromagnetic layer 10 in the y direction shown in fig. 5 and 6 is narrower from the first surface 10a toward the second surface 10b, and is wider after reaching the shortest width L10 min. The position having the shortest width L10min is closer to the nonmagnetic layer 30 side than the center of the first ferromagnetic layer 10 in the z direction, for example. The width of the first ferromagnetic layer 10 in the y direction shown in fig. 5 and 6 is longest on the second surface 10 b. The width of the second surface 10b in the y direction shown in fig. 5 and 6 is longer than the width L30 of the nonmagnetic layer 30 in the y direction. The longest width L10max in the y direction of the first ferromagnetic layer 10 is longer than the width L30 in the y direction of the nonmagnetic layer 30, for example.

The first ferromagnetic layer 10 shown in fig. 5 and 6 has a y-direction side surface inclined in the y-direction with respect to the z-direction. The y-direction side surface of the first ferromagnetic layer 10 may be divided into a first inclined surface s1 and a second inclined surface s 2. The first inclined surface s1 is an inclined surface that is inclined toward the y-direction center of the first ferromagnetic layer 10 with respect to the lower end of the side surface of the first ferromagnetic layer 10 on the substrate Sub side. The second inclined surface s2 is an inclined surface that is inclined toward the y-direction center of the first ferromagnetic layer 10 with respect to the upper end of the side surface of the first ferromagnetic layer 10 on the nonmagnetic layer 30 side. The second inclined surface s2 overhangs (overhang) with respect to the first inclined surface s 1.

The first inclined surface s1 and the second inclined surface s2 sandwich the inflection point p1 where the inclination of the tangent to the side surface of the first ferromagnetic layer 10 with respect to the z direction is zero. The inflection point p1 is located further inward than the y-direction end of the nonmagnetic layer 30. The y-direction side surface of the first ferromagnetic layer 10 is recessed from an imaginary plane that descends from the y-direction end of the nonmagnetic layer 30 in the z-direction, for example.

The first ferromagnetic layer 10 is made of a magnetic body. The first ferromagnetic layer 10 preferably contains at least one element selected from Co, Ni, Fe, Pt, Pd, Gd, Tb, Mn, Ge, and Ga. Examples of the material used for the first ferromagnetic layer 10 include a laminated film of Co and Ni, a laminated film of Co and Pt, a laminated film of Co and Pd, a MnGa-based material, a GdCo-based material, and a TbCo-based material. The saturation magnetization of a ferrimagnet (ferrimagnet) such as a MnGa-based material, a GdCo-based material, or a TbCo-based material is small, and the threshold current required for moving the magnetic domain wall DW is small. Further, the multilayer film of Co and Ni, the multilayer film of Co and Pt, and the multilayer film of Co and Pd have a large coercive force and a low moving speed of the magnetic domain wall DW.

The first ferromagnetic layer 10 may also contain an element constituting the base layer 40. In terms of the abundance of the element, for example, the first region R1 located closer to the base layer 40 side than the position where the first ferromagnetic layer 10 becomes the shortest width L10min in the z direction is richer than the second region R2 located closer to the nonmagnetic layer 30 side than the position where the first ferromagnetic layer 10 becomes the shortest width L10min in the z direction.

"nonmagnetic layer"

The nonmagnetic layer 30 is, for example, in contact with the first ferromagnetic layer 10. The nonmagnetic layer 30 is on the first ferromagnetic layer 10. The nonmagnetic layer 30 is between the first ferromagnetic layer 10 and the second ferromagnetic layer 20.

The nonmagnetic layer 30 is made of, for example, a nonmagnetic insulator, a semiconductor, or a metal. The non-magnetic insulator being, for example, Al₂O₃、SiO₂、MgO、MgAl₂O₄And materials in which a part of Al, Si, and Mg is substituted by Zn, Be, or the like. These materials have a large band gap and excellent insulating properties. When the nonmagnetic layer 30 is made of a nonmagnetic insulator, the nonmagnetic layer 30 is a tunnel barrier layer. The nonmagnetic metal is, for example, Cu, Au, Ag, or the like. Nonmagnetic semiconductors such as Si, Ge, CuInSe₂、CuGaSe₂、Cu(In,Ga)Se₂And the like.

The milling rate of the non-magnetic layer 30 is, for example, slower than the milling rate of the first ferromagnetic layer 10. The milling rate is the milling rate for dry etching. In dry etching, ion beam etching is used, for example. In ion beam etching, rare gas elements such as Ar, Kr, and Xe, or ions thereof can be used for milling accelerated at a voltage of several hundred to several kV. In the case where the nonmagnetic layer 30 is an oxide, the milling rate is generally slow compared to the first ferromagnetic layer 10 which is a metal.

The thickness of the nonmagnetic layer 30 is preferably setAbove, more preferablyThe above. If the thickness of the nonmagnetic layer 30 is thick, the resistance area product (RA) of the magnetic domain wall moving element 100 becomes large. The domain wall moving element 100 preferably has a resistance area product (RA) of 1 × 10⁴Ωμm²Above, more preferably 1 × 10⁵Ωμm²The above. The resistance area product (RA) of the domain wall moving element 100 is represented by the product of the element resistance of one domain wall moving element 100 and the element cross-sectional area (the area of a cut surface that cuts the nonmagnetic layer 30 in the xy plane) of the domain wall moving element 100.

In addition, since the thickness of the nonmagnetic layer 30 is thick and the milling rate is different from that of other layers when the nonmagnetic layer is thinned, impurities tend to be easily reattached to the side wall of the nonmagnetic layer 30. If the relationship between the y-direction width L30 of the nonmagnetic layer 30 and the y-direction shortest width L10min of the first ferromagnetic layer 10 is controlled, reattachment of impurities to the side wall of the nonmagnetic layer 30 can be suppressed even when the nonmagnetic layer 30 is thick.

"second ferromagnetic layer"

The second ferromagnetic layer 20 is located on the nonmagnetic layer 30. The second ferromagnetic layer 20 has a magnetization M oriented in one direction₂₀. Magnetization M of the second ferromagnetic layer 20₂₀When a predetermined external force is applied to the magnetization M of the domain wall moving region 13_13A、M_13BIn contrast, magnetization reversal is not easy. The predetermined external force is, for example, an external force applied to magnetization by an external magnetic field or an external force applied to magnetization by a spin-polarized current. The second ferromagnetic layer 20 is sometimes referred to as a magnetization pinned layer or a magnetization reference layer.

Due to the magnetization of the second ferromagnetic layer 20 and the magnetization M of the domain wall moving region 13_13A、M_13BAnd thus the resistance value of the domain wall moving element 100 varies. Magnetization M of first magnetic region 13A_13AFor example, the magnetization M of the second ferromagnetic layer 20₂₀The magnetization M of the second magnetic region 13B in the same direction (parallel)_13BFor example, the magnetization M of the second ferromagnetic layer 20₂₀The opposite direction (anti-parallel). If the area of the first magnetic region 13A in a portion overlapping with the second ferromagnetic layer 20 is enlarged when viewed from the z direction in plan, the resistance value of the domain wall moving element 100 decreases. In contrast, if the area of the second magnetic region 13B in a portion overlapping with the second ferromagnetic layer 20 is enlarged when viewed from the z direction in plan, the resistance value of the domain wall moving element 100 increases.

The second ferromagnetic layer 20 contains a ferromagnetic body. The second ferromagnetic layer 20 contains, for example, a material that easily achieves a coherent tunneling effect with the first ferromagnetic layer 10. The second ferromagnetic layer 20 contains, for example, a metal selected from Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, an alloy containing these metals and at least one or more of B, C and N, and the like. The second ferromagnetic layer 20 is, for example, Co-Fe-B, Ni-Fe.

The second ferromagnetic layer 20 may be, for example, Heusler alloy (Heusler alloy). Heusler alloys are semi-metals with high spin polarizability. The heusler alloy being of XYZ or X₂YZ, X is a transition metal element or a noble metal element of Co, Fe, Ni, or Cu group in the periodic table, Y is a transition metal or an element type of X of Mn, V, Cr, or Ti group, and Z is a typical element of III to V group. Examples of the heusler alloy include Co₂FeSi、Co₂FeGe、Co₂FeGa、Co₂MnSi、Co₂Mn_1-aFe_aAl_bSi_1-b、Co₂FeGe_1-cGa_cAnd the like.

When the magnetization easy axis of the second ferromagnetic layer 20 is set to the z direction (set to a perpendicular magnetization film), the film thickness of the second ferromagnetic layer 20 is preferably 1.5nm or less, and more preferably 1.0nm or less. If the thickness of the second ferromagnetic layer 20 is reduced, perpendicular magnetic anisotropy (interfacial perpendicular magnetic anisotropy) is added to the second ferromagnetic layer 20 at the interface between the second ferromagnetic layer 20 and another layer (nonmagnetic layer 30), and the magnetization of the second ferromagnetic layer 20 is easily oriented in the z direction.

When the magnetization easy axis of the second ferromagnetic layer 20 is set to the z direction (to be a perpendicular magnetization film), the second ferromagnetic layer 20 is preferably a laminate of a ferromagnetic material selected from Co, Fe, and Ni and a nonmagnetic material selected from Pt, Pd, Ru, and Rh, and more preferably an intermediate layer selected from Ir and Ru is inserted at any position of the laminate. When a ferromagnetic body and a nonmagnetic body are laminated, perpendicular magnetic anisotropy can be added, and the magnetization of the second ferromagnetic layer 20 is easily oriented in the z direction by interposing an intermediate layer.

An antiferromagnetic layer may be provided on the surface of the second ferromagnetic layer 20 on the side opposite to the nonmagnetic layer 30 via a spacer layer. The second ferromagnetic layer 20, the spacer layer, and the antiferromagnetic layer form a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a nonmagnetic layer. By the antiferromagnetic coupling of the second ferromagnetic layer 20 and the antiferromagnetic layer, the coercive force of the second ferromagnetic layer 20 becomes larger than that in the case where there is no antiferromagnetic layer. The antiferromagnetic layer is, for example, IrMn, PtMn, or the like. The spacer layer contains, for example, at least one selected from Ru, Ir, Rh.

The matrix layer 40 is on the opposite side of the first ferromagnetic layer 10 from the nonmagnetic layer 30. The matrix layer 40 may also be only at a position overlapping the domain wall moving region 13 in the z direction.

The base layer 40 is made of a non-magnetic material. The matrix layer 40 defines, for example, the crystal structure of the first ferromagnetic layer 10. The crystallinity of the first ferromagnetic layer 10 is improved and the orientation of the magnetization of the first ferromagnetic layer 10 is improved as compared with the crystal structure of the underlayer 40. The crystalline structure of matrix layer 40 is, for example, amorphous, (001) oriented NaCl structure, formed from ABO₃A (002) -oriented perovskite structure, a (001) -oriented tetragonal structure, or a cubic structure.

Matrix layer 40 is a conductor or an insulator. Matrix layer 40 is preferably a conductor. In the case where the base layer 40 is a conductor, the thickness of the base layer 40 is preferably thinner than the thickness of the first ferromagnetic layer 10. Underlayer 40 contains, for example, Ta, Ru, Pt, Ir, Rh, W, Pd, Cu, Au, and Cu. The underlayer 40 is, for example, a Ta layer, a Pt layer, a stacked body of a Ta layer and a Pt layer.

The milling rate of the matrix layer 40 is, for example, slower than the first ferromagnetic layer 10. The milling rate of the base layer 40 is slower than the first and second conductive portions 51 and 52, for example. For example, the underlayer 40 contains one or more elements selected from Al, Cr, Mg, Ta, Ti, and W, the first ferromagnetic layer 10 contains one or more elements selected from Co, Fe, Ni, Pt, Pd, Ir, and Rh, and the relationship described above is satisfied when the first conductive portion 51 and the second conductive portion 52 are an alloy or a laminate containing one or more elements selected from Au, Cu, and Ru. Specifically, for example, the underlayer may be a stacked film of Ta or Ta and Pt, the first ferromagnetic layer 10 may be a stacked film of Co and Pt, and the first conductive sections 51 and the second conductive sections 52 may be Au.

The thickness of matrix layer 40 is substantially constant in the xy plane, for example. Matrix layer 40 has an average thickness of, for exampleThe following. The average thickness is an average value of the thicknesses of foundation layer 40 measured at x-direction positions of ten portions each of which is obtained by dividing foundation layer 40 at equal intervals in the x-direction.

"first conductive part and second ferromagnetic part"

The first conductive portion 51 and the second conductive portion 52 are electrically connected to the first ferromagnetic layer 10. The first conductive portion 51 and the second conductive portion 52 are connected via the base layer 40 as shown in fig. 6, for example. The first conductive portion 51 and the second conductive portion 52 may be directly connected to the first ferromagnetic layer 10. The first conductive portion 51 is connected to, for example, a first end portion of the first ferromagnetic layer 10, and the second conductive portion 52 is connected to, for example, a second end portion of the first ferromagnetic layer 10. The first conductive portion 51 and the second conductive portion 52 are, for example, connections between the wiring W and the first ferromagnetic layer 10.

The first conductive portion 51 and the second conductive portion 52 are columnar bodies. The first conductive part 51 and the second conductive part 52 shown in fig. 4 have a rectangular shape when viewed from the z direction. The first conductive portion 51 and the second conductive portion 52 may have a circular, elliptical, or irregular shape in a plan view in the z direction. The widths of the first conductive portion 51 and the second conductive portion 52 in the y direction are wider than the widths of the first ferromagnetic layer 10 and the nonmagnetic layer 30 in the y direction, for example. The upper surfaces of the first conductive portion 51 and the second conductive portion 52 are, for example, etched and recessed with respect to the xy plane.

The first conductive portion 51 and the second conductive portion 52 are made of a material having conductivity. The first conductive part 51 and the second conductive part 52 include, for example, magnetic materials. The first conductive portion 51 and the second conductive portion 52 are made of, for example, a metal selected from Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, an alloy containing these metals and at least one or more of B, C and N, or the like. The first conductive portion 51 and the second conductive portion 52 are made of, for example, Co-Fe-B, Ni-Fe, etc. When the magnetization easy axis is set to be the z direction (i.e., a perpendicular magnetization film), the first conductive portion 51 and the second conductive portion 52 are preferably a laminate of a ferromagnetic material selected from Co, Fe, and Ni and a nonmagnetic material selected from Pt, Pd, Ru, and Rh. The first conductive portion 51 and the second conductive portion 52 may have a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a nonmagnetic layer. The respective magnetizations of the two magnetic layers are fixed, with the directions of the fixed magnetizations being opposite.

When the first conductive part 51 includes a magnetic body, the magnetization M of the first conductive part 51₅₁Oriented in one direction. Magnetization M₅₁For example, oriented in the + z direction. The first conductive part 51 fixes the magnetization M of the magnetization fixing region 11₁₁. Magnetization M of first conductive part 51₅₁And magnetization M of the magnetization fixed region 11₁₁For example, oriented in the same direction.

When the second conductive part 52 contains a magnetic body, the magnetization M of the second conductive part 52₅₂Magnetization M along with first conductive portion 51₅₁Oriented in the opposite direction. Magnetization M₅₂For example, oriented in the-z direction. In this case, the second conductive part 52 fixes the magnetization M of the magnetization fixed region 12₁₂Magnetization M of second conductive part 52₅₂And magnetization M of the magnetization fixed region 12₁₂For example, oriented in the same direction.

The direction of magnetization of each layer of the domain wall moving element 100 can be confirmed by measuring a magnetization curve, for example. The magnetization curve can be measured, for example, using MOKE (Magneto Optical Kerr Effect). The measurement based on MOKE is a measurement method using a magneto-optical effect (magnetic Kerr effect) in which linearly polarized light is incident on a measurement object and rotation of the polarization direction occurs.

Next, a method of manufacturing the magnetic memory array 200 will be described. The magnetic memory array 200 is formed by a lamination process of each layer and a processing process of processing a part of each layer into a predetermined shape. The layers can be stacked by a sputtering method, a Chemical Vapor Deposition (CVD) method, an electron beam evaporation method (EB evaporation method), an atomic laser deposition method, or the like. The processing of each layer can be performed using photolithography or the like.

First, impurities are doped at predetermined positions of the substrate Sub to form a source region S and a drain region D. Next, a gate insulating film GI and a gate electrode G are formed between the source region S and the drain region D. The source region S, the drain region D, the gate insulating film GI, and the gate electrode G form a transistor Tr.

Next, an insulating layer In is formed so as to cover the transistor Tr. Further, an opening is formed In the insulating layer In, and a conductor is filled In the opening to form the wiring W. The first wiring Wp and the second wiring Cm are formed by stacking the insulating layer In to a predetermined thickness, forming a groove In the insulating layer In, and filling the groove with a conductor.

The first conductive portion 51 and the second conductive portion 52 can be formed by, for example, stacking a ferromagnetic layer on one surface of the insulating layer In and the wiring W and removing portions other than the portions to be the first conductive portion 51 and the second conductive portion 52. The removed portion is buried with an insulating layer In, for example.

Next, the base layer 40, the first ferromagnetic layer 10, and the nonmagnetic layer 30 are sequentially stacked on the first conductive portion 51, the second conductive portion 52, and the insulating layer In. Then, a resist is formed on a part of the nonmagnetic layer 30. Next, the underlayer 40, the first ferromagnetic layer 10, and the nonmagnetic layer 30 are processed by dry etching from the z direction through a resist. The yz cross-sectional shape of the processed laminate was rectangular or trapezoidal.

Next, the first ferromagnetic layer 10 of the laminate is aimed and irradiated with an ion beam from an oblique direction. The first ferromagnetic layer 10 is recessed toward the center of the y direction of the laminated body by irradiation of the ion beam. After that, the second ferromagnetic layer 20 is laminated at a position overlapping the first ferromagnetic layer 10.

Finally, the ion beam is irradiated from the lateral direction of the laminate while reducing the irradiation angle of the ion beam with respect to the xy plane, thereby thinning the entire laminate. The laminate is made finer by the reduction in thickness. Finally, the periphery of the stacked body is filled with the insulating layer In, thereby obtaining the domain wall moving element 100.

When the magnetic domain wall moving element 100 of the first embodiment is thinned, impurities are difficult to re-attach to the side surfaces of the nonmagnetic layer 30. The reason for this will be described with reference to fig. 7. Fig. 7 is a schematic view for explaining thinning when the magnetic domain wall moving element 100 of the first embodiment is manufactured.

As described above, the ion beam IB is irradiated from the y direction to the laminated body including the underlayer 40, the first ferromagnetic layer 10, the nonmagnetic layer 30, and the second ferromagnetic layer 20 during the thinning. It is difficult to irradiate the ion beam IB parallel to the y direction, and the ion beam IB is irradiated from a direction slightly inclined to the z direction with respect to the xy plane. For example, if the first ferromagnetic layer 10 is irradiated with the ion beam IB, the metal particles contained in the first ferromagnetic layer 10 are scattered as particles pt.

In the domain wall moving element 100 of the first embodiment, since the shortest width L10min in the y direction of the first ferromagnetic layer 10 is shorter than the width L30 in the y direction of the nonmagnetic layer 30, the nonmagnetic layer 30 serves as a cap, and the particles pt can be prevented from adhering to the side wall of the nonmagnetic layer 30 again.

In addition, if the first ferromagnetic layer 10 has the second inclined surface s2, the second inclined surface s2 overhangs with respect to the first inclined surface s1, and therefore, the particles pt can be further suppressed from reaching the side wall of the nonmagnetic layer 30. In addition, if the position where the y-direction width of the first ferromagnetic layer 10 is the shortest is on the nonmagnetic layer 30 side of the center of the first ferromagnetic layer 10 in the z direction, the portion close to the nonmagnetic layer 30 is recessed inward, and the particles pt can be further suppressed from reaching the side wall of the nonmagnetic layer 30.

If the milling rate of the nonmagnetic layer 30 and the foundation layer 40 is made slower than that of the first ferromagnetic layer 10, the side surface of the first ferromagnetic layer 10 enters the side surface of the nonmagnetic layer 30 and the foundation layer 40 inward as the thickness is made thinner. Therefore, the nonmagnetic layer 30 serves as a cap, and the particles pt can be further suppressed from adhering to the side wall of the nonmagnetic layer 30 again. Further, if the milling rate of the underlayer 40 is made slower than the milling rates of the first conductive part 51 and the second conductive part 52, the underlayer 40 serves as a cover, and the particles pt scattered from the first conductive part 51 or the second conductive part 52 can be further suppressed from reaching the side wall of the nonmagnetic layer 30.

In addition, if the first ferromagnetic layer 10 contains an element constituting the underlayer 40, the amount of the particles pt scattering from the first ferromagnetic layer 10 can be reduced. Further, by making the abundance of the element constituting the underlayer 40 of the first region R1 richer than that of the second region R2, it is possible to suppress the generation of the particles pt from the first region R1 in which the path for the particles pt to reach the nonmagnetic layer 30 is easily ensured.

The impurities formed by the particles adhering thereto lower the MR ratio of the domain wall moving element 100, and in some cases, short-circuit the first ferromagnetic layer 10 and the second ferromagnetic layer 20. The domain wall moving element 100 of the first embodiment can reduce the adhesion of impurities to the sidewall of the nonmagnetic layer 30, and thus has high reliability.

Although the magnetic memory array 200 and the domain wall motion element 100 of the first embodiment have been described in detail above, the magnetic memory array 200 and the domain wall motion element 100 of the first embodiment can be modified and changed in various ways within the scope of the present invention.

(first modification)

Fig. 8 is a yz cross-sectional view at the center in the x direction of the magnetic domain wall moving element 101 of the first modification. The side surface of the first ferromagnetic layer 10 of the domain wall moving element 101 has a different shape from that of the domain wall moving element 100. In the domain wall moving element 101, the same components as those of the domain wall moving element 100 are denoted by the same reference numerals, and description thereof is omitted.

The y-direction side surface of the first ferromagnetic layer 10 shown in fig. 8 is an inclined surface s3 inclined in the y-direction with respect to the z-direction. The inclined surface s3 is an inclined surface that is inclined away from the y-direction center of the first ferromagnetic layer 10 with respect to the upper end of the side surface of the first ferromagnetic layer 10 on the nonmagnetic layer 30 side.

The width of the first surface 10a in the y direction shown in fig. 8 is shorter than the width L30 of the nonmagnetic layer 30 in the y direction. The width of the first ferromagnetic layer 10 in the y direction shown in fig. 8 becomes wider from the first surface 10a toward the second surface 10 b. The first ferromagnetic layer 10 shown in fig. 8 has the shortest width in the y direction on the first surface 10a and the longest width on the second surface 10 b.

In the domain wall moving element 101 according to the first modification, a part of the y-direction side surface of the first ferromagnetic layer 10 is located inside the nonmagnetic layer 30. Therefore, the nonmagnetic layer 30 serves as an eave, and the particles pt scattered from the first ferromagnetic layer 10 can be prevented from adhering to the side wall of the nonmagnetic layer 30 again.

(second modification)

Fig. 9 is a yz cross-sectional view at the center in the x direction of the magnetic domain wall moving element 102 of the second modification. The side of the first ferromagnetic layer 10 of the domain wall-moving element 102 has a different shape from that of the domain wall-moving element 100. In the domain wall moving element 102, the same structures as those of the domain wall moving element 100 are denoted by the same reference numerals, and description thereof is omitted.

The domain wall-moving element 102 of the second modification is the same as the domain wall-moving element 100 at the point where the y-direction width of the first ferromagnetic layer 10 is the longest on the second surface 10b, but differs from the domain wall-moving element 100 at the point where the y-direction width of the second surface 10b is shorter than the y-direction width L30 of the nonmagnetic layer 30. In the domain wall moving element 102 of the second modification example, for example, the longest width L10max in the y direction of the first ferromagnetic layer 10 is shorter than the width L30 in the y direction of the nonmagnetic layer 30.

In the domain wall-moving element 102 according to the second modification, the y-direction side surface of the first ferromagnetic layer 10 is located inward of the nonmagnetic layer 30. Therefore, the nonmagnetic layer 30 serves as an eave, and the particles pt scattered from the first ferromagnetic layer 10 can be prevented from adhering to the side wall of the nonmagnetic layer 30 again.

(third modification)

Fig. 10 is a yz cross-sectional view at the center in the x direction of the magnetic domain wall moving element 103 of the third modification. The domain wall moving element 103 is different from the domain wall moving element 100 in the point having the metal layer 60 on the side of the second ferromagnetic layer 20. In the domain wall moving element 103, the same structures as those of the domain wall moving element 100 are denoted by the same reference numerals, and description thereof is omitted.

The metal layer 60 is, for example, located on the y-direction side of the second ferromagnetic layer 20. The metal layer 60 is, for example, in contact with the y-direction side surface of the second ferromagnetic layer 20. Additional layers may also be present between the second ferromagnetic layer 20 and the metal layer 60. The other layer is, for example, an oxide film.

The metal layer 60 is not continuous with the second ferromagnetic layer 20. Discontinuous means that the interface can be confirmed by transmission electron microscopy. The metal layer 60 is different from the second ferromagnetic layer 20. The difference from the second ferromagnetic layer 20 means a difference in material or composition. The metal layer 60 may be a non-magnetic material or a magnetic material.

The domain wall moving element 103 of the third modification can obtain the same effects as the domain wall moving element 100 of the first embodiment. In addition, since the metal layer 60 protrudes outward from the first ferromagnetic layer 10, the domain wall moving element 103 has improved heat dissipation properties.

"second embodiment"

Fig. 11 is a cross-sectional view of cutting off the domain wall moving element 110 of the second embodiment in an xz plane passing through the center of the first ferromagnetic layer 70 in the y direction. Fig. 12 is a cross-sectional view in which the domain wall moving element 110 is cut off in the yz plane passing through the center of the x direction of the domain wall moving element 110. A plan view of the magnetic domain wall moving element 110 of the second embodiment viewed from the z direction is the same as that of fig. 4.

The domain wall moving element 110 has, for example, a first ferromagnetic layer 70, a second ferromagnetic layer 80, a nonmagnetic layer 30, a substrate layer 40, a first conductive part 51, and a second conductive part 52. In the magnetic domain wall moving element 110, the same structures as those of the first embodiment are denoted by the same reference numerals. The first ferromagnetic layer 70 is located closer to the substrate Sub side than the second ferromagnetic layer 0.

When writing data to the domain wall moving element 110, a write current is made to flow through the second ferromagnetic layer 80 between the first conductive portion 51 and the second conductive portion 52. When reading data from the domain wall moving element 100, a read current is passed between the first conductive portion 51 or the second conductive portion 52 and the first ferromagnetic layer 70.

The first ferromagnetic layer 70 has a magnetization M oriented in one direction₇₀. The first ferromagnetic layer 70 is a magnetization pinned layer and a magnetization reference layer. The first ferromagnetic layer 70 is functionally equivalent to the second ferromagnetic layer 20 of the first embodiment. The magnetic domain wall moving element 110 is an end pin structure in which a magnetization fixed layer is at the substrate Sub side. The same material as the second ferromagnetic layer 20 can be used for the first ferromagnetic layer 70. First ferromagnetic layer 70 may also include elements that constitute matrix layer 40.

A write current is passed through the second ferromagnetic layer 80. The second ferromagnetic layer 80 is functionally the same as the first ferromagnetic layer 10 of the first embodiment. The second ferromagnetic layer 80 can use the same material as the first ferromagnetic layer 10.

The second ferromagnetic layer 80 is a layer capable of magnetically storing information by a change in internal magnetic state. The second ferromagnetic layer 80 is sometimes referred to as a magnetic storage layer, a domain wall moving layer. The second ferromagnetic layer 80 has magnetization fixed regions 81 and 82 and a domain wall moving region 83. Magnetization M of the magnetization fixed region 81₈₁And magnetization M of the magnetization fixed region 82₈₂Oriented in the opposite direction. The domain wall moving region 83 has a first magnetic region 83A and a second magnetic region 83B. The boundary of the first and second magnetic regions 83A and 83B is a magnetic domain wall DW. Magnetization M_83AAnd magnetization M_84AAre oriented in opposite directions sandwiching a magnetic domain wall DW.

As shown in fig. 12, the shortest width L70min in the y direction of the first ferromagnetic layer 70 is shorter than the width L30 in the y direction of the nonmagnetic layer 30. The width of the first ferromagnetic layer 70 in the y direction differs depending on the position in the z direction. For example, the first surface 70a and the second surface 70b of the first ferromagnetic layer 70 have different widths in the y direction. The width of the first ferromagnetic layer 70 in the y direction decreases from the first surface 10a toward the second surface 10b, and increases after reaching the shortest width L70 min. The position having the shortest width L70min is closer to the nonmagnetic layer 30 than the center of the first ferromagnetic layer 10 in the z direction, for example. The longest width L70max in the y direction of the first ferromagnetic layer 70 is longer than the width L30 in the y direction of the nonmagnetic layer 30, for example.

The y-direction side surface of the first ferromagnetic layer 70 is inclined in the y-direction with respect to the z-direction, for example. The y-direction side surface of the first ferromagnetic layer 70 may be divided into a first inclined surface s1 and a second inclined surface s 2. The y-direction side surface of the first ferromagnetic layer 70 is recessed from an imaginary plane that descends from the y-direction end of the nonmagnetic layer 30 in the z-direction, for example.

The milling rate of the non-magnetic layer 30 is, for example, slower than the milling rate of the first ferromagnetic layer 70. The milling rate of the matrix layer 40 is, for example, slower than the first ferromagnetic layer 70.

In the domain wall moving element 110 according to the second embodiment, the shortest width L70min in the y direction of the first ferromagnetic layer 70 is shorter than the width L30 in the y direction of the nonmagnetic layer 30, so the nonmagnetic layer 30 serves as a shield and the particles pt can be prevented from adhering to the side wall of the nonmagnetic layer 30 again. The domain wall moving element 110 of the second embodiment achieves the same effects as the domain wall moving element 100 of the first embodiment. In addition, the domain wall-moving element 110 of the second embodiment may select the same modification as that of the first embodiment.

The preferred embodiments of the present invention have been described above in detail. The characteristic configurations in the respective embodiments and modifications may be combined.