JP7470599B2 - Wiring layer, domain wall motion element and magnetic array - Google Patents

Description

The present invention relates to a wiring layer, a domain wall motion element, and a magnetic array.

Attention is being focused on next-generation non-volatile memory to replace flash memory and other memory devices, which are reaching the limits of miniaturization. For example, MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistive Random Access Memory), and PCRAM (Phase Change Random Access Memory) are known as next-generation non-volatile memories.

MRAM uses the change in resistance value caused by a change in the magnetization direction to record data. Data recording is performed by each of the magnetoresistance change elements that make up the MRAM. For example, Patent Document 1 describes a magnetoresistance change element (domain wall motion element) that can record multi-value data by moving the domain wall in the first ferromagnetic layer (domain wall motion layer). Patent Document 1 also describes the formation of magnetization fixed regions at both ends of the first ferromagnetic layer in order to control the range of domain wall motion and prevent the first ferromagnetic layer from becoming a single magnetic domain.

Patent No. 5445970

The domain wall motion layer, in which the domain wall moves, often has a fixed magnetization region at both ends to prevent the domain wall from reaching either end and disappearing. If the domain wall invades the fixed magnetization region, the domain wall may disappear. Since the domain wall motion element records data at the position of the domain wall, if the domain wall disappears, data cannot be recorded.

The present invention was made in consideration of the above problems, and aims to provide a wiring layer, a domain wall motion element, and a magnetic array that can better prevent single magnetic domain formation.

(1) The wiring layer according to the first aspect has a domain wall displacement layer that extends in a first direction and can have a domain wall therein, and a magnetic body that has a portion embedded in the domain wall displacement layer and is made of a different material or has a different laminated structure from the domain wall displacement layer.

(2) In the wiring layer according to the above aspect, the domain wall displacement layer has a first region that is outside the end of the magnetic body that is closer to the center of the domain wall displacement layer in the first direction, and a second region other than the first region, and the magnetic body may be in contact with the first region.

(3) The wiring layer according to the above aspect may have two of the magnetic bodies, and the two magnetic bodies may be spaced apart in the first direction.

(4) The wiring layer according to the above aspect may further include an interlayer region between the magnetic body and the domain wall displacement layer.

(5) In the wiring layer according to the above aspect, the magnetic body may have an inclined surface at the interface with the domain wall displacement layer that is inclined with respect to a plane perpendicular to the first direction.

(6) In the wiring layer according to the above aspect, the magnetic body may have a curved surface at the interface with the domain wall displacement layer.

(7) In the wiring layer according to the above aspect, the magnetic body may be exposed on a first surface in the thickness direction.

(8) In the wiring layer according to the above aspect, the width of the magnetic body in a second direction perpendicular to the first direction may be wider than the width of the domain wall displacement layer in the second direction.

(9) In the wiring layer according to the above aspect, the magnetic body may be located so as to overlap with a first end of the domain wall displacement layer in the first direction.

(10) In the wiring layer according to the above aspect, the magnetic body may penetrate the domain wall displacement layer in the thickness direction.

(11) The wiring layer according to the above aspect may further include a second magnetic body connected to a portion of the magnetic body that is exposed from the domain wall displacement layer.

(12) In the wiring layer according to the above aspect, the second magnetic body may have an inclined surface that is inclined with respect to a plane perpendicular to the first direction.

(13) In the wiring layer according to the above aspect, the second magnetic body may also be in contact with the domain wall displacement layer.

(14) In the wiring layer according to the above aspect, the magnetic body and the second magnetic body may be integrated.

(15) The wiring layer according to the above aspect may further include a spacer layer between the magnetic body and the second magnetic body.

(16) The domain wall motion element of the second aspect comprises a wiring layer of the above aspect and a conductor connected to the wiring layer, and the conductor is connected to the magnetic body.

(17) The domain wall motion element of the third aspect comprises a wiring layer of the above aspect and a conductor connected to the wiring layer, and the conductor is connected to the second magnetic body.

(18) The domain wall motion element of the fourth aspect may include a ferromagnetic layer that is positioned to overlap the domain wall motion layer in the thickness direction, and a non-magnetic layer that is between the wiring layer and the ferromagnetic layer.

(19) The domain wall motion element according to the above aspect may include a conductor connected to the wiring layer, and the magnetic body may be between the conductor and the non-magnetic layer in the first direction when viewed from the thickness direction.

(20) The magnetic array according to the fifth aspect has a plurality of domain wall motion elements according to the above aspect.

The wiring layer, domain wall motion element, and magnetic array according to the above aspects are less likely to become a single magnetic domain.

FIG. 1 is a configuration diagram of a magnetic array according to a first embodiment. 3 is a cross-sectional view of a characteristic portion of the magnetic array according to the first embodiment. FIG. 1 is a cross-sectional view of a domain wall motion element according to a first embodiment. FIG. 2 is a plan view of the domain wall motion element according to the first embodiment. FIG. 11 is a cross-sectional view of a domain wall motion element according to a first modified example. FIG. 11 is a cross-sectional view of a domain wall motion element according to a second modified example. FIG. 13 is a cross-sectional view of a domain wall motion element according to a third modified example. FIG. 13 is a cross-sectional view of a domain wall motion element according to a fourth modified example. FIG. 13 is a cross-sectional view of a domain wall motion element according to a fifth modified example. FIG. 13 is a cross-sectional view of a domain wall motion element according to a sixth modified example. FIG. 13 is a cross-sectional view of a domain wall motion element according to a seventh modified example. FIG. 13 is a cross-sectional view of a domain wall motion element according to an eighth modified example. FIG. 13 is a plan view of a domain wall motion element according to a ninth modified example. FIG. 23 is a cross-sectional view of a domain wall motion element according to a tenth modified example. FIG. 23 is a cross-sectional view of a domain wall motion element according to an eleventh modified example.

The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show enlarged characteristic parts for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited to them. Appropriate changes can be made within the scope of the effects of the present invention.

First, the directions are defined. The x and y directions are substantially parallel to one surface of the substrate Sub (see FIG. 2) described later. The x direction is the direction in which the wiring layer 10 described later extends. The x direction is an example of a first direction. The y direction is a direction perpendicular to the x direction. The y direction is an example of a second direction. The z direction is a direction from the substrate Sub described later toward the domain wall motion element 100. The z direction coincides with, for example, the stacking direction of the wiring layer 10. The z direction is an example of a thickness direction. In this specification, "extending in the x direction" means, for example, that the dimension in the x direction is larger than the smallest dimension among the dimensions in the x direction, y direction, and z direction. The same applies to the case of extending in other directions.

[First embodiment]
1 is a configuration diagram of a magnetic array according to a first embodiment. The magnetic array 200 includes a plurality of domain wall motion elements 100, a plurality of first wirings Wp, a plurality of second wirings Cm, a plurality of third wirings Rp, a plurality of first switching elements SW1, a plurality of second switching elements SW2, and a plurality of third switching elements SW3. The magnetic array 200 can be used, for example, in a magnetic memory, a multiply-and-accumulate calculator, a neuromorphic device, or a magneto-optical element.

<First Wiring, Second Wiring, Third Wiring>
Each of the first wirings Wp is a write wiring. Each of the first wirings Wp electrically connects a power source to one or more of the domain wall motion elements 100. The power source is connected to one end of the magnetic array 200 during use.

Each of the second wirings Cm is a common wiring. The common wiring is a wiring that can be used both when writing and reading data. Each of the second wirings Cm electrically connects a reference potential to one or more domain wall motion elements 100. The reference potential is, for example, ground. The second wirings Cm may be provided for each of the multiple domain wall motion elements 100, or may be provided across the multiple domain wall motion elements 100.

Each of the third wirings Rp is a read wiring. Each of the third wirings Rp electrically connects a power source to one or more domain wall motion elements 100. The power source is connected to one end of the magnetic array 200 during use.

<First Switching Element, Second Switching Element, Third Switching Element>
1, a first switching element SW1, a second switching element SW2, and a third switching element SW3 are connected to each of the multiple domain wall motion elements 100. The first switching element SW1 is connected between the domain wall motion element 100 and a first wiring Wp. The second switching element SW2 is connected between the domain wall motion element 100 and a second wiring Cm. The third switching element SW3 is connected between the domain wall motion element 100 and a third wiring Rp.

When the first switching element SW1 and the second switching element SW2 are turned ON, a write current flows between the first wiring Wp and the second wiring Cm connected to a specific domain wall motion element 100. When the second switching element SW2 and the third switching element SW3 are turned ON, a read current flows between the second wiring Cm and the third wiring Rp connected to a specific domain wall motion element 100.

The first switching element SW1, the second switching element SW2, and the third switching element SW3 are elements that control the flow of current. The first switching element SW1, the second switching element SW2, and the third switching element SW3 are, for example, elements that use a phase change in a crystal layer such as a transistor or an Ovonic Threshold Switch (OTS), elements that use a change in band structure such as a Metal-Insulator Transition (MIT) switch, elements that use a breakdown voltage such as a Zener diode and an avalanche diode, and elements whose conductivity changes with a change in atomic position.

Any of the first switching element SW1, the second switching element SW2, and the third switching element SW3 may be shared by domain wall motion elements 100 connected to the same wiring. For example, when the first switching element SW1 is shared, one first switching element SW1 is provided upstream of the first wiring Wp. For example, when the second switching element SW2 is shared, one second switching element SW2 is provided upstream of the second wiring Cm. For example, when the third switching element SW3 is shared, one third switching element SW3 is provided upstream of the third wiring Rp.

Figure 2 is a cross-sectional view of a main part of the magnetic array 200 according to the first embodiment. Figure 2 is a cross-section of one domain wall motion element 100 in Figure 1 cut along the xz plane passing through the center of the width of the wiring layer 10 in the y direction.

The first switching element SW1 and the second switching element SW2 shown in FIG. 2 are transistors Tr. The transistor Tr has a gate electrode G, a gate insulating film GI, and a source region S and a drain region D formed in a substrate Sub. The substrate Sub is, for example, a semiconductor substrate. The third switching element SW3 is electrically connected to the third wiring Rp and is, for example, shifted in the y direction in FIG. 2.

Each of the transistors Tr and the domain wall motion element 100 are electrically connected via wiring w1 and w2. Wiring w1 and w2 contain a conductive material. Wiring w1 is a via wiring extending in the z direction. Wiring w2 is an in-plane wiring extending in any direction within the xy plane. Wiring w1 and w2 are formed within an opening in the insulating layer 90.

The insulating layer 90 is an insulating layer that insulates between the wirings of the multilayer wiring and between the elements. The domain wall motion element 100 and the transistor Tr are electrically isolated by the insulating layer 90, except for the wirings w1 and w2. The insulating layer 90 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 ₂ O ₃ ), zirconium oxide (ZrO _x ), or the like.

"Magnetic domain wall motion element"
Fig. 3 is a cross-sectional view of the domain wall motion element 100 cut along an xz plane passing through the center in the y direction of the wiring layer 10. Fig. 4 is a plan view of the domain wall motion element 100 as viewed from the z direction.

The domain wall motion element 100 has a wiring layer 10, a non-magnetic layer 30, and a ferromagnetic layer 20. The domain wall motion element 100 is covered with an insulating layer 90. When writing data to the domain wall motion element 100, a write current is passed along the wiring layer 10. When reading data from the domain wall motion element 100, a current is applied in the z direction of the domain wall motion element 100, and a read current is passed between the electrode E and any of the wirings w1 connected to the wiring layer 10.

The wiring layer 10 has a domain wall displacement layer 11, a magnetic body 12, and a magnetic body 13. The magnetic body 13 is an example of a second magnetic body. The wiring layer 10 is a wiring through which a write current flows when writing data.

The domain wall displacement layer 11 extends in the x-direction. The domain wall displacement layer 11 has multiple magnetic domains therein, and has a domain wall DW at the boundary between the multiple magnetic domains. The domain wall displacement layer 11 is, for example, a layer capable of magnetically recording information by changing the magnetic state. The domain wall displacement layer 11 may be called a ferromagnetic layer or a magnetic recording layer.

The domain wall displacement layer 11 has a first region A1 and a second region A2. The first region A1 is a region that is outside the end of the magnetic body 12 that is closer to the center of the domain wall displacement layer 11 in the x direction in the x direction. There are, for example, two first regions A1, and the two first regions A1 sandwich the second region A2 in the x direction. The first region A1 is, for example, a region that overlaps with the magnetic body 12 when viewed from the z direction. The second region A2 is a region other than the first region A1 of the domain wall displacement layer 11.

The first region A1 is a region in which the magnetization direction is fixed in one direction. "The magnetization direction is fixed in one direction" means that the magnetization direction does not change when an external force strong enough to reverse the magnetization of the second region A2 is applied. The magnetization orientation directions of the two first regions A1 on either side of the second region A2 are opposite.

The second region A2 is a region where the magnetization direction can change and the domain wall DW can move. The second region A2 has a first magnetic domain A21 and a second magnetic domain A22. The magnetization M _A21 of the first magnetic domain A21 and the magnetization M A22 of the second magnetic domain _A22 are oriented in opposite directions. The first magnetic domain A21 has the same magnetization orientation direction as the adjacent first region A1, and the second magnetic domain A22 has the same magnetization orientation direction as the adjacent first region A1.

The boundary between the first magnetic domain A21 and the second magnetic domain A22 is the domain wall DW. In principle, the domain wall DW moves within the second area A2 and does not invade the first area A1.

When the ratio of the first magnetic domain A21 to the second magnetic domain A22 in the second region A2 changes, the domain wall DW moves. The domain wall DW moves by applying a write current in the x direction of the second region A2. For example, when a write current (e.g., a current pulse) in the +x direction is applied to the second region A2, electrons flow in the -x direction opposite to the current, and the domain wall DW moves in the -x direction. When a current flows from the first magnetic domain A21 to the second magnetic domain A22, electrons spin-polarized in the second magnetic domain A22 reverse the magnetization M _A21 of the first magnetic domain A21. The magnetization reversal of the magnetization M _A21 of the first magnetic domain A21 causes the domain wall DW to move in the -x direction.

The domain wall displacement layer 11 is made of a magnetic material. The domain wall displacement layer 11 preferably contains at least one element selected from the group consisting of Co, Ni, Fe, Pt, Pd, Gd, Tb, Mn, Ge, and Ga. Examples of materials used for the domain wall displacement layer 11 include a laminated film of Co and Ni, a laminated film of Co and Pt, a laminated film of Co and Pd, an MnGa-based material, a GdCo-based material, and a TbCo-based material. Ferrimagnetic materials such as MnGa-based materials, GdCo-based materials, and TbCo-based materials have low saturation magnetization, and the threshold current required to move the domain wall DW is small. In addition, the laminated film of Co and Ni, the laminated film of Co and Pt, and the laminated film of Co and Pd have a high coercive force, and the movement speed of the domain wall DW is slow.

A part of the magnetic body 12 is embedded in the domain wall displacement layer 11. The magnetic body 12 fits into an opening formed in the domain wall displacement layer 11. A part of the magnetic body 12 is embedded in the first region A1. A part of the magnetic body 12 may be exposed from the domain wall displacement layer 11, for example. For example, there are two magnetic bodies 12, which are spaced apart from each other. For example, the two magnetic bodies 12 sandwich the non-magnetic layer 30 in the x direction when viewed from the z direction.

The magnetic body 12 is in contact with the domain wall displacement layer 11, for example, at the bottom and side surfaces. The magnetic body 12 shown in FIG. 3 is exposed to the first surface 10a of the wiring layer 10. The second surface 10b of the wiring layer 10 is flat. The first surface 10a is the surface of the wiring layer 10 that is in contact with the non-magnetic layer 30, and the second surface 10b is the surface opposite to the first surface 10a. The magnetic body 12 may be contained within the domain wall displacement layer 11, or may be exposed to the second surface 10b.

The magnetic body 12 can be made of the same material as the magnetic domain wall displacement layer 11. However, the magnetic body 12 is different in material or laminated structure from the magnetic domain wall displacement layer 11. A different laminated structure means that the layer configuration, such as the composition, material, and number of layers, of the laminated layers is different. The magnetic body 12 can be a single magnetic body or a laminate of multiple layers. When the magnetic body 12 is a single magnetic body, it is easy to manufacture, and when the magnetic body 12 is made of multiple layers, the coercive force, etc. can be finely adjusted.

The magnetic body 12 has an inclined surface 12c at the interface with the domain wall displacement layer 11 that is inclined with respect to the yz plane perpendicular to the x direction. The inclined surface 12c is, for example, the side surface of the magnetic body 12 on the non-magnetic layer 30 side. When the side surface of the magnetic body 12 is inclined, the contact area between the magnetic body 12 and the domain wall displacement layer 11 increases, and the magnetic coupling between the magnetic body 12 and the domain wall displacement layer 11 is strengthened. In addition, since the interface between the magnetic body 12 and the domain wall displacement layer 11 has a width in the x direction, it is possible to more effectively prevent the domain wall DW from penetrating into the first region A1.

As shown in FIG. 4, the shape of the magnetic body 12 when viewed from the z direction is, for example, rectangular. The shape of the magnetic body 12 when viewed from the z direction is not limited to this case. For example, the shape of the magnetic body 12 when viewed from the z direction may be rectangular, circular, elliptical, oval, etc.

As shown in FIG. 4, for example, the width L12 of the magnetic body 12 in the y direction is longer than the width L11 of the domain wall displacement layer 11. The boundary between the magnetic body 12 and the domain wall displacement layer 11 extends in the y direction of the domain wall displacement layer 11, so that the magnetic property distribution in the y direction in the domain wall displacement layer 11 becomes uniform. When the magnetic property distribution in the y direction in the domain wall displacement layer 11 becomes uniform, the domain wall DW can be prevented from tilting with respect to the y direction.

The magnetic body 13 is not embedded in the domain wall displacement layer 11 of the magnetic body 12, but is connected to a portion exposed from the domain wall displacement layer 11. The magnetic body 13 protrudes, for example, from the upper surface of the domain wall displacement layer 11 in the z direction. The magnetic body 13 is in contact with the magnetic body 12. The direction of the magnetization _M13 of the magnetic body 13 is, for example, the same as the direction of the magnetization _M12 of the adjacent magnetic body 12. By stacking the magnetic body 13 on the magnetic body 12, it becomes more difficult for the magnetization of the first region A1 to be reversed, and it is possible to more effectively prevent the domain wall DW from invading the first region A1.

The magnetic body 13 may be made of the same material as the magnetic body 12. The magnetic body 13 and the magnetic body 12 may be made of the same material and integrated together. The magnetic body 13 is a conductor and also serves as an electrode connecting the wiring w1 and the wiring layer 10. In addition, heat generated in the ferromagnetic layer 20 is discharged through the magnetic body 13, improving the heat dissipation of the domain wall motion element 100.

The magnetic body 13 has, for example, an inclined surface 13c that is inclined with respect to the yz plane. The inclined surface 13c is, for example, the side surface of the magnetic body 13 on the nonmagnetic layer 30 side. When the side surface of the magnetic body 13 is inclined, a leakage magnetic field from the inclined surface 13c is applied to the first region A1, which makes it possible to better prevent the domain wall DW from penetrating into the first region A1.

As shown in FIG. 4, the shape of magnetic body 13 when viewed from the z direction is substantially the same as that of magnetic body 12. For example, the width of magnetic body 13 in the y direction is substantially the same as the width of magnetic body 12 in the y direction. The width of magnetic body 13 in the y direction may be wider than the width of magnetic body 12 in the y direction.

A conductive wiring w1 is connected to the magnetic body 13. The magnetic body 13 is connected to the transistor Tr via the wiring w1, etc.

The non-magnetic layer 30 is located between the domain wall displacement layer 11 and the ferromagnetic layer 20. The non-magnetic layer 30 is laminated on one side of the domain wall displacement layer 11.

The nonmagnetic layer 30 is made of, for example, a nonmagnetic insulator, semiconductor, or metal. The nonmagnetic insulator is, for example, Al ₂ O ₃ , SiO ₂ , MgO, MgAl ₂ O ₄ , and materials in which a part of Al, Si, and Mg is replaced with 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. The nonmagnetic semiconductor is, for example, Si, Ge, CuInSe ₂ , CuGaSe ₂ , Cu(In,Ga)Se ₂ , or the like.

The thickness of the nonmagnetic layer 30 is, for example, 20 Å or more, and may be 25 Å or more. If the thickness of the nonmagnetic layer 30 is large, the resistance area area (RA) of the domain wall motion element 100 becomes large. The resistance area area (RA) of the domain wall motion element 100 is preferably 1×10 ⁴ Ωμm ² or more, and more preferably 5×10 ⁴ Ωμm ² or more. The resistance area area (RA) of the domain wall motion element 100 is expressed as the product of the element resistance of one domain wall motion element 100 and the element cross-sectional area of the domain wall motion element 100 (the area of a cross section obtained by cutting the nonmagnetic layer 30 in the xy plane).

The ferromagnetic layer 20 is laminated on the non-magnetic layer 30. The ferromagnetic layer 20 is located so as to overlap with the second region A2 of the domain wall displacement layer 11 in the z-direction. The magnetization _M20 of the ferromagnetic layer ₂₀ is more difficult to reverse than the magnetizations M _A21 and M _A22 of the second region A2 of the domain wall displacement layer 11. The magnetization M20 of the ferromagnetic layer 20 does not change direction and is fixed when an external force strong enough to reverse the magnetization of the second region A2 is applied. The ferromagnetic layer 20 may be referred to as a magnetization fixed layer or a magnetization reference layer.

The ferromagnetic layer 20 includes a ferromagnetic material. The ferromagnetic layer 20 includes, for example, a material that is easy to obtain a coherent tunnel effect between the domain wall displacement layer 11 and the ferromagnetic layer 20. The ferromagnetic layer 20 includes, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, an alloy containing these metals and at least one of the elements B, C, and N, and the like. The ferromagnetic layer 20 is, for example, Co-Fe, Co-Fe-B, or Ni-Fe.

The ferromagnetic layer 20 may be, for example, a Heusler alloy. The Heusler alloy is a half metal and has a high spin polarization. The Heusler alloy is an intermetallic compound having a chemical composition of XYZ or X ₂ YZ, where X is a transition metal element or a noble metal element of the Co, Fe, Ni, or Cu group on the periodic table, Y is a transition metal element or an element type of X of the Mn, V, Cr, or Ti group, and Z is a typical element of groups III to V. Examples of Heusler alloys include Co ₂ FeSi, Co ₂ FeGe, Co ₂ FeGa, Co ₂ MnSi, Co ₂ Mn _1-a Fe _a Al _b Si _1-b , and Co ₂ FeGe _1-c Ga _c .

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

Next, a method for manufacturing the magnetic array 200 will be described. The magnetic 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 lamination of each layer can be performed using a sputtering method, a chemical vapor deposition (CVD) method, an electron beam deposition method (EB deposition 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 into 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 the transistor Tr.

Next, an insulating layer 90 is formed to cover the transistor Tr. An opening is formed in the insulating layer 90, and the opening is filled with a conductor to form the wiring w1. The first wiring Wp, the second wiring Cm, the third wiring Rp, and the wiring w2 are formed by stacking the insulating layer 90 to a predetermined thickness, forming a groove in the insulating layer 90, and filling the groove with a conductor.

The domain wall displacement layer 11 is laminated on the insulating layer 90. The non-magnetic layer 30 and the ferromagnetic layer 20 are laminated on the domain wall displacement layer 11. The non-magnetic layer 30 and the ferromagnetic layer 20 are processed into a predetermined shape. An opening is provided at a predetermined position in the domain wall displacement layer 11, and the opening is filled with the magnetic material 12. A magnetic material 13 may be added on top of the magnetic material 12. The domain wall displacement layer 11, the magnetic materials 12, and 13 form the wiring layer 10. By the above procedure, the domain wall displacement element 100 is obtained.

In the domain wall motion element 100 according to the first embodiment, the magnetization of the first region A1 is strongly fixed by embedding the magnetic body 12 in the domain wall motion layer 11. As a result, even if an unintended external force or the like occurs, the domain wall DW does not invade the first region A1, and the domain wall motion layer 11 can be prevented from becoming a single magnetic domain.

An example of the magnetic array 200 and domain wall motion element 100 according to the first embodiment has been described in detail, but the magnetic array 200 and domain wall motion element 100 according to the first embodiment can be modified and changed in various ways within the scope of the present invention.

(First Modification)
5 is a cross-sectional view of the domain wall motion element 101 according to the first modified example taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 5, a description of the same configuration as in FIG.

The domain wall motion element 101 has a spacer layer 14 between the magnetic body 12 and the magnetic body 13. The spacer layer 14 is a non-magnetic layer. The spacer layer 14 is, for example, Ru, Ir, or Rh. The magnetic body 12, the spacer layer 14, and the magnetic body 13 are stacked along an opening formed in the insulating layer 90 and the domain wall motion layer 11. The opening is formed at a predetermined position, for example, after the domain wall motion layer 11, the non-magnetic layer 30, and the ferromagnetic layer 20 are stacked in this order and the periphery is filled with the insulating layer 90.

The magnetic body 12 and the magnetic body 13 are, for example, antiferromagnetically coupled. The magnetization _M12 of the magnetic body 12 and the magnetization _M13 of the magnetic body 13 have opposite magnetization orientation directions. The magnetic body 13 may be made of, for example, the same material as the magnetic body 12, an antiferromagnetic film, or the like. The magnetic body 12 and the magnetic body 13 may be ferromagnetically coupled. The magnetization _M12 of the magnetic body 12 is strongly fixed by being coupled with the magnetization _M13 of the magnetic body 13.

The product of the film thickness and saturation magnetization of the magnetic body 12 is approximately the same as the product of the film thickness and saturation magnetization of the magnetic body 13. For example, the magnetic body 12 and the magnetic body 13 sandwich the spacer layer 14 to form a synthetic antiferromagnetic structure. The product of the film thickness and saturation magnetization of the magnetic body 12 may be different from the product of the film thickness and saturation magnetization of the magnetic body 13. If the product of the film thickness and saturation magnetization differs between the magnetic body 12 and the magnetic body 13, it becomes easier to determine the initial state of magnetization during manufacturing. When the application of the external magnetic field is stopped after the application of the external magnetic field, the magnetization of the magnetic body with the larger product of the film thickness and saturation magnetization is oriented in the direction of application of the external magnetic field, and the magnetization of the magnetic body with the smaller product of the film thickness and saturation magnetization is oriented in the opposite direction to the application of the external magnetic field. Also, the product of the film thickness and saturation magnetization of the magnetic body 12 connected to the first end of the domain wall displacement layer 11 may be made larger than the product of the film thickness and saturation magnetization of the magnetic body 13, and the product of the film thickness and saturation magnetization of the magnetic body 12 connected to the second end of the domain wall displacement layer 11 may be made smaller than the product of the film thickness and saturation magnetization of the magnetic body 13. With this configuration, the initial state of magnetization can be easily determined by simply applying an external magnetic field in one direction.

The domain wall motion element 101 according to the first modified example has the same effect as the domain wall motion element 100 according to the first embodiment. Furthermore, when the magnetic body 12 and the magnetic body 13 are antiferromagnetically coupled, the effect of the leakage magnetic field from the magnetic body 12 and the magnetic body 13 can be reduced.

(Second Modification)
6 is a cross-sectional view of the domain wall motion element 102 according to the second modified example taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 6, a description of the same configuration as in FIG.

The magnetic body 12 of the domain wall motion element 102 has a curved surface 12d at the interface with the domain wall motion layer 11. When the interface between the magnetic body 12 and the domain wall motion layer 11 is curved, localized concentration of the write current can be avoided. This is because the current tends to concentrate in parts where the shape changes suddenly, such as corners.

The domain wall motion element 102 according to the second modified example has the same effect as the domain wall motion element 100 according to the first embodiment. In addition, by suppressing localized concentration of the write current, bias in the current density and heat generation at the interface between the magnetic body 12 and the domain wall motion layer 11 can be suppressed.

(Third Modification)
7 is a cross-sectional view of the domain wall motion element 103 according to the third modified example taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 7, a description of the same configuration as in FIG.

The domain wall motion element 103 has an interlayer region 15 between the magnetic body 12 and the domain wall motion layer 11. The interlayer region 15 contains, for example, a mixture of elements constituting the domain wall motion layer 11 and different elements. The different elements are, for example, heavy metal elements such as Fe, Co, Ni, Cu, Ta, Ru, Pd, Pt, and W, and rare gas elements such as Ar, Kr, and Xe.

The heterogeneous elements become trap sites for the domain wall DW and inhibit the movement of the domain wall DW. Furthermore, the implantation of the heterogeneous elements creates unevenness at the interface between the domain wall displacement layer 11 and the magnetic body 12, increasing the contact area between the domain wall displacement layer 11 and the magnetic body 12. When the contact area between the domain wall displacement layer 11 and the magnetic body 12 increases, the magnetic coupling between the domain wall displacement layer 11 and the magnetic body 12 becomes stronger, and the magnetization of the first region A1 is strongly fixed.

In addition, the domain wall motion element 103 according to the third modified example has the same effects as the domain wall motion element 100 according to the first embodiment.

(Fourth Modification)
8 is a cross-sectional view of the domain wall motion element 104 according to the fourth modified example taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 8, a description of the same configuration as in FIG.

The domain wall motion element 104 is located at a position where the magnetic body 12 overlaps with the first end of the domain wall motion layer 11 in the z direction. A part of the magnetic body 12 protrudes from the domain wall motion layer 11 in the x direction.

When the magnetic body 12 is at the end of the domain wall motion layer 11, the second region A2 can be secured widely. The domain wall DW moves within the second region A2, and the domain wall motion element 104 stores data according to the position of the domain wall DW. By expanding the range of movement of the domain wall DW, the number of gradations of the data of the domain wall motion element 104 can be increased.

In addition, the domain wall motion element 104 according to the fourth modified example has the same effects as the domain wall motion element 100 according to the first embodiment.

(Fifth Modification)
9 is a cross-sectional view of the domain wall motion element 105 according to the fifth modified example taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 9, a description of the same configuration as in FIG.

In the domain wall motion element 105, the magnetic body 12 penetrates the domain wall motion layer 11 in the z-direction. A part of the magnetic body 12 protrudes from the lower surface of the domain wall motion layer 11.

The domain wall motion element 105 according to the fifth modified example has the same effect as the domain wall motion element 100 according to the first embodiment. In addition, the magnetic body 12 penetrates the domain wall motion layer 11, and the magnetic body 12 divides the domain wall motion layer 11 in the x direction, which further prevents the domain wall DW from reaching the end of the domain wall motion layer 11.

(Sixth Modification)
10 is a cross-sectional view of the domain wall motion element 106 according to the sixth modified example taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 10, a description of the same configuration as in FIG.

In the domain wall motion element 106, the magnetic body 13 is in contact with the magnetic body 12 and the domain wall motion layer 11. The width in the x direction of the lower surface of the magnetic body 13 is, for example, wider than the width in the x direction of the upper surface of the magnetic body 12.

The domain wall motion element 106 according to the sixth modified example has the same effect as the domain wall motion element 100 according to the first embodiment. In addition, the magnetization of the first region A1 is fixed by the magnetic bodies 12 and 13, so that the magnetization of the first region A1 is more difficult to reverse.

(Seventh Modification)
11 is a cross-sectional view of the domain wall motion element 107 according to the seventh modification taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 11, a description of the same configuration as in FIG.

The domain wall motion element 107 does not have a magnetic body 13. The magnetic body 12 of the domain wall motion element 107 is directly connected to the wiring w1, which is a conductor.

The domain wall motion element 107 according to the seventh modified example provides the same effects as the domain wall motion element 100 according to the first embodiment.

(Eighth Modification)
12 is a cross-sectional view of the domain wall motion element 108 according to the eighth modified example taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 12, a description of the same configuration as in FIG.

When viewed from the z direction, the domain wall motion element 108 is located in a position where the wiring w1 and the magnetic body 12 do not overlap. The magnetic body 12 is located between the wiring w1 and the non-magnetic layer 30 in the x direction. The wiring w1 is connected at a position other than the domain wall motion layer 11 and the magnetic body 12.

The domain wall motion element 108 according to the eighth modified example has the same effect as the domain wall motion element 100 according to the first embodiment. The presence of the magnetic body 12 before the point where the write current flows through the wiring w1 can more effectively prevent the domain wall DW from reaching the end of the domain wall motion layer 11. In addition, the increased area of the first region A1 strengthens the spin polarization of the electrons that reach the second region A2.

(Ninth Modification)
13 is a plan view of a domain wall motion element 109 according to a ninth modified example, viewed from the z direction. In FIG. 13, the description of the same configuration as in FIG.

The width L12 of the magnetic body 12 in the y direction is shorter than the width L11 of the domain wall displacement layer 11. The magnetic body 12 contacts the domain wall displacement layer 11 at its bottom and side surfaces. The side surfaces of the magnetic body 12 in the y direction also contact the domain wall displacement layer 11, increasing the contact area between the domain wall displacement layer 11 and the magnetic body 12.

The domain wall motion element 109 according to the ninth modified example provides the same effects as the domain wall motion element 100 according to the first embodiment.

(Tenth Modification)
14 is a cross-sectional view of the domain wall motion element 110 according to the tenth modification taken along an xz plane passing through the center in the y direction of the wiring layer 10. In FIG. 14, a description of the same configuration as in FIG.

The domain wall motion element 110 does not have a non-magnetic layer 30 or a ferromagnetic layer 20. The domain wall motion element 110 is an optical element that utilizes the magneto-optical effect. Depending on the position of the domain wall DW in the domain wall motion layer 11, the phase of the reflected light or transmitted light incident on the domain wall motion layer 11 changes.

The domain wall motion element 110 according to the tenth modification example has the same effect as the domain wall motion element 100 according to the first embodiment.

In addition, the side of the magnetic body 12 does not have to be inclined or curved. The magnetic body 12 may not be exposed on the surface of the domain wall displacement layer 11, but may be contained within the domain wall displacement layer 11. As in the domain wall displacement element 111 shown in FIG. 15, the surface where the wiring w1 is connected to the domain wall displacement layer 11 does not have to coincide with the surface where the magnetic body 12 is exposed.

The above describes the preferred embodiment of the present invention in detail. The characteristic configurations in the embodiment and the modified examples may be combined with each other.

10 Wiring layer 10a First surface 10b Second surface 11 Domain wall motion layer 12, 13 Magnetic body 12c, 13c Inclined surface 12d Curved surface 14 Spacer layer 15 Interlayer region 20 Ferromagnetic layer 30 Nonmagnetic layer 90 Insulating layer 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110 Domain wall motion element 200 Magnetic array A1 First region A2 Second region A21 First magnetic domain A22 Second magnetic domain DW Domain wall

Claims (21)

a magnetic domain wall displacement layer extending in a first direction and capable of having a magnetic domain wall therein;
a magnetic body having a portion embedded in the domain wall displacement layer and having a material or a laminated structure different from that of the domain wall displacement layer;
an interlayer region between the magnetic body and the domain wall displacement layer;
the interlayer region contains a mixture of an element constituting the domain wall displacement layer and a different element,
The different element is at least one heavy metal element selected from the group consisting of Fe, Co, Ni, Cu, Ta, Ru, Pd, Pt, and W, or a rare gas element;
The interlayer region forms unevenness between the magnetic body and the domain wall displacement layer . the domain wall displacement layer has a first region that is located outside an end of the magnetic body on a center side of the domain wall displacement layer in the first direction, and a second region other than the first region,
The wiring layer according to claim 1 , wherein the magnetic body is in contact with the first region. The magnetic body has two magnetic bodies.
The wiring layer according to claim 1 , wherein the two magnetic bodies are spaced apart from each other in the first direction. The wiring layer according to any one of claims 1 to 3, wherein the magnetic body has an inclined surface at the interface with the interlayer region that is inclined with respect to a plane perpendicular to the first direction. The wiring layer according to any one of claims 1 to 4, wherein the magnetic body has a curved surface at the interface with the interlayer region. The wiring layer according to any one of claims 1 to 5, wherein the width of the magnetic body in a second direction perpendicular to the first direction is wider than the width of the domain wall displacement layer in the second direction. The wiring layer according to any one of claims 1 to 6, wherein the magnetic body is positioned so as to overlap with a first end of the domain wall displacement layer in the first direction. The wiring layer according to any one of claims 1 to 7, wherein the magnetic body penetrates the domain wall displacement layer in the thickness direction. The wiring layer according to any one of claims 1 to 8, wherein the magnetic body penetrates the domain wall displacement layer in the thickness direction and protrudes from a first surface of the domain wall displacement layer and a second surface opposite to the first surface. The wiring layer according to any one of claims 1 to 9, further comprising a second magnetic body connected to a portion of the magnetic body that is exposed from the domain wall displacement layer. The wiring layer according to claim 10, wherein the second magnetic body has an inclined surface that is inclined with respect to a plane perpendicular to the first direction. The wiring layer according to claim 10 or 11, wherein the second magnetic body is also in contact with the domain wall displacement layer. The wiring layer according to any one of claims 10 to 12, wherein the magnetic body and the second magnetic body are integrated. The wiring layer according to any one of claims 10 to 13, further comprising a spacer layer between the magnetic body and the second magnetic body. The wiring layer according to claim 14, wherein the product of the film thickness and saturation magnetization of the magnetic body is different from the product of the film thickness and saturation magnetization of the second magnetic body. The wiring layer according to any one of claims 1 to 15,
a conductor connected to the wiring layer,
The conductor is connected to the magnetic body. The wiring layer according to any one of claims 11 to 15,
a conductor connected to the wiring layer,
The conductor is connected to the second magnetic body. The wiring layer according to any one of claims 1 to 15,
a conductor connected to the wiring layer,
the conductor is connected to the domain wall displacement layer,
A domain wall motion element, wherein a surface of the domain wall motion layer to which the conductor is connected is different from a surface of the domain wall motion layer on the side of the magnetic material. The wiring layer according to any one of claims 1 to 15,
a ferromagnetic layer located at a position overlapping the domain wall displacement layer in a thickness direction;
a non-magnetic layer between the wiring layer and the ferromagnetic layer. A conductor connected to the wiring layer is further provided.
The domain wall motion element according to claim 19 , wherein the magnetic body is located between the conductor and the non-magnetic layer in the first direction when viewed in a thickness direction. A magnetic array having a plurality of domain wall motion elements according to any one of claims 16 to 20.

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