JP2024061529A - Magnetic domain wall displacement type device and method of manufacturing the same - Google Patents

Abstract

To provide a method of manufacturing a magnetic domain wall displacement type device that has an array of magnetic domain wall displacement elements having magnetic films excellent in magnetic characteristics although formed of a material low in heat resistance.SOLUTION: The present invention relates to a method of manufacturing a magnetic domain wall displacement type device that has a magnetic domain wall displacement element arrayed, and the magnetic domain wall displacement element comprises a magnetic thin wire 1 which comprises a magnetic layer 11 and is formed into a thin wire, and electrodes 21, 22 which are connected to both ends of the magnetic thin wire. The method comprises in order; a mask stage of forming a mask on a substrate 71, a region where the magnetic thin wire 1 is formed and a region where a frame body 6 encircling the whole magnetic thin wire 1 in plan view is formed being bored in the mask; a magnetic thin wire material deposition stage of depositing the material of the magnetic thin wire 1 on the substrate 71; a lift-off stage of dissolving away the mask; and a substrate joining stage of sticking the substrate 73, having the electrodes 21, 22 formed thereon, on the substrate 71 at a room temperature so that the electrodes 21, 22 are joined to the magnetic thin wire 1.SELECTED DRAWING: Figure 7

Description

The present invention relates to a domain wall motion device in which domain wall motion elements are arranged, and a method for manufacturing the same.

In magnetoresistive random access memory (MRAM), which uses the high and low resistance of the magnetoresistive element in the memory cell as binary data, MRAMs using the domain wall motion method (e.g., Patent Document 1) and the SOT (Spin Orbit Torque) method (e.g., Patent Documents 2 and 3) have been developed to increase speed and reduce current as a method of writing, i.e., magnetization reversal of a portion of the magnetic film (free layer) of the magnetoresistive element.

In the domain wall motion type MRAM, the free layer of the magnetoresistance effect element is formed into a thin wire extending on both sides, and the magnetization direction is changed between two predetermined points in the longitudinal direction. In detail, a magnetic body formed into a thin wire with a width of several nm to several hundred nm (hereinafter, magnetic thin wire) is likely to generate two or more magnetic domains in the longitudinal direction, and when a current is supplied in the longitudinal direction (thin wire direction) at a predetermined current density or more, the domain wall generated to separate the magnetic domains moves in the opposite direction of the current (towards the positive pole) due to the STT (Spin Transfer Torque) effect (Non-Patent Document 1). In addition, magnetization reversal in a predetermined region (magnetization reversible region) of such a magnetic thin wire is used to develop a magneto-optical spatial light modulator in which the magnetic thin wire is formed of a magneto-optical material and used as an optical modulation element (for example, Patent Document 4). Furthermore, racetrack memories (e.g., Patent Documents 5 to 7) and spatial light modulators (e.g., Patent Documents 8 and 9) have been developed that simplify the structure and miniaturize the cells by configuring each row of arranged memory cells or pixels with a magnetic domain in a single magnetic nanowire.

In SOT-MRAM, when a current is supplied in one direction (x direction) in the film surface (xy plane) to a channel layer made of Ta (tantalum) or the like stacked on the free layer of a magnetoresistance effect element, electrons with spins in the opposite directions in the y direction are stored separately in the upper and lower surface layers, and the electrons near the interface with the free layer reverse the magnetization direction of the free layer. In the SOT method, magneto-optical spatial light modulators have also been developed in which a channel layer is stacked on a magnetic fine wire formed of a magneto-optical material to form an optical modulation element (for example, Patent Documents 10 and 11). The channel layer has the spin Hall effect (SHE), and is made of high-density, paramagnetic transition metals such as Ta, Pt (platinum), and W (tungsten) (for example, Non-Patent Documents 2 and 3), or topological insulators such as BiSb and BiSe (for example, Non-Patent Documents 4 and 5). It is known that when a topological insulator, especially BiSb, is applied to the channel layer, a huge spin torque can be applied to the magnetic material through the junction interface, resulting in a high SOT effect (Non-Patent Document 4). It is also known that the SOT effect also acts on the domain wall motion in magnetic nanowires (e.g., Non-Patent Documents 2, 3, 5), and it is expected that the domain wall motion will be faster and have a lower current than the STT effect. In particular, racetrack memories and spatial light modulators with similar structures are required to have longer magnetic nanowires in order to increase capacity and improve resolution, but magnetic nanowires tend to heat up when supplied with current, and low current is required to suppress deterioration.

Patent No. 5598697 International Publication No. 2017/090730 International Publication No. 2019/054484 Patent No. 4939489 U.S. Pat. No. 6,834,005 Patent No. 4969981 JP 2016-157815 A Patent No. 5782334 Patent No. 6302759 JP 2020-134754 A JP 2022-83931 A

A. Yamaguchi, T. Ono, S. Nasu, "Real-Space Observation of Current-Driven Domain Wall Motion in Submicron Magnetic Wires", Physical Review Letters, Volume 92, 077205, 2004 A. V. Khvalkovskiy, V. Cros, D. Apalkov, V. Nikitin, M. Krounbi, K. A. Zvezdin, A. Anane, J. Grollier, A. Fert, "Matching domain-wall configuration and spin-orbit torques for efficient domain-wall motion", Physical Review B87, 020402(R), 2013 Kenichi Aoshima, Nobuhiko Funabashi, Ryo Higashida, Kenji Machida, "Current induced domain wall motion with a Ta/Gd-Fe/Si-N magnetic nanowire for a magneto-optical light modulator", AIP Advances 10, 015336, 2020 Nguyen Huynh Duy Khang et al., "Ultralow power spin-orbit torque magnetization switching induced by a non-epitaxial topological insulator on Si substrates", Scientific Reports, Volume 10, 12185, 12185.1-12185.12, 2020 M. Nakatani, M. Takahashi, K. Ogura, N. Ishii, Pham Nam Hai, and Y. Miyamoto, “Current-driven magnetic domains in a magnetic nanowire with a topological insulator BiSb”, Abstracts of the 45th Annual Meeting of the Magnetic Society of Japan, 01aB-2, 2021

Many magnetic materials have magnetic properties such as coercivity and magneto-optical properties that deteriorate when heated to temperatures between about 100°C and below 200°C. In particular, when a laminate of BiSb and a magnetic film is heat-treated at a relatively low temperature of about 150°C, the Bi and Sb in the BiSb diffuse into the magnetic film, which may cause the magnetic properties of the magnetic film to deteriorate (Non-Patent Document 5). For this reason, it is difficult to apply such materials to magnetoresistance effect elements and light modulation elements (domain wall motion elements) that have magnetic fine wires. Specifically, in the photolithography process, the photoresist hardening (baking) temperature is about 150°C or higher, and the development (dissolving of the photoresist) temperature is about 70 to 90°C. In addition, the plasma ashing temperature in the resist mask removal process is about 160°C. The magnetic film or laminate can be shaped into a fine wire shape or the like by a lift-off method in which a resist mask is formed before the film is formed, and by dissolving and removing the resist mask. However, the domain wall motion element requires electrodes made of Au, Cu, etc., and readout elements to be connected to a certain area on the magnetic nanowire. Electrodes, etc. can be embedded in the insulating film before the magnetic nanowire is formed and connected to the underside of the magnetic nanowire, but depending on the structure of the domain wall motion element, they may only be formed after the magnetic nanowire is formed. A technique for printing conductive paste has been developed as a wiring formation technique that does not rely on photolithography, but heat treatment is required to sinter the conductive paste.

The present invention was devised in consideration of the above problems, and aims to provide a domain wall motion device in which domain wall motion elements having magnetic films with good magnetic properties are arranged, and a method for manufacturing the same.

That is, the method for manufacturing a domain wall motion device according to the present invention is a method for manufacturing a domain wall motion device in which domain wall motion elements are arranged, each of which includes a magnetic fine wire formed in a fine wire shape with a magnetic layer made of a magnetic material, and an electrode connected to a part of the magnetic fine wire in the fine wire direction. The method for manufacturing this domain wall motion device sequentially performs a masking process for forming a mask on a first substrate that has an area in which the magnetic fine wires are formed and a frame-shaped area that surrounds all of the magnetic fine wires in a planar view, a magnetic fine wire material deposition process for depositing a material for the magnetic fine wires on the first substrate, a lift-off process for removing the mask at 90°C or less, and a substrate bonding process for bonding a second substrate on which the electrodes are formed to the first substrate at 90°C or less so that the electrodes are bonded to the magnetic fine wires.

The domain wall motion device according to the present invention is configured to include magnetic domain wall motion elements arranged on a substrate, the magnetic domain wires each having a magnetic layer made of a magnetic material and formed into a fine line shape, and an electrode connected to a portion of the magnetic domain wall motion elements in the fine line direction, and further includes an integral insulating layer that fills the gap between the electrodes or is provided on the electrodes, and a frame body made of the same material as the magnetic domain wires, sandwiched between the insulating layer and the substrate and surrounding the region in which the domain wall motion elements are arranged, and at least one of the side surfaces of the magnetic domain wires and the top surface other than the connection portion with the electrode, and at least a portion of the inner side surface of the frame body are exposed.

The method for manufacturing a domain wall motion device according to the present invention makes it possible to obtain a domain wall motion device in which domain wall motion elements exhibiting desired magnetic properties are arranged. And, according to the domain wall motion device according to the present invention, the domain wall motion elements exhibit desired magnetic properties.

1 is an external view illustrating a structure of a domain wall motion type device according to the present invention. 1 is a schematic diagram illustrating a structure of a domain wall motion type device according to a first embodiment of the present invention, and is a partial cross-sectional view of FIG. 3 is a side view of a domain wall motion element of the domain wall motion type device shown in FIG. 2 and is a partial cross-sectional view of FIG. 1 is a flowchart illustrating a method for manufacturing a domain wall motion type device according to a first embodiment of the present invention. 1A to 1C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a first embodiment of the present invention, and are partial cross-sectional views in an electrode substrate formation step. 1A to 1C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a first embodiment of the present invention, and are partial cross-sectional views in an electrode substrate formation step. 1A to 1C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a first embodiment of the present invention, and are partial cross-sectional views in an electrode substrate formation step. 1A to 1C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a first embodiment of the present invention, and are partial cross-sectional views in a masking step. 1A to 1C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a first embodiment of the present invention, and are partial cross-sectional views in a magnetic nanowire material film formation step. 1A to 1C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a first embodiment of the present invention, and are partial cross-sectional views in a substrate bonding step. FIG. 4 is a schematic diagram illustrating a structure of a domain wall motion type device according to a second embodiment of the present invention, and corresponds to the partial cross-sectional view of FIG. 8 is a side view of a domain wall motion element of the domain wall motion type device shown in FIG. 3 and a partial cross-sectional view of FIG. 10 is a flowchart illustrating a method for manufacturing a domain wall motion type device according to a second embodiment of the present invention. 11A to 11C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a second embodiment of the present invention, and are partial cross-sectional views in a magnetic member forming step. 11A to 11C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a second embodiment of the present invention, and are partial cross-sectional views in a magnetic member forming step. 11A to 11C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a second embodiment of the present invention, and are partial cross-sectional views in a magnetic member forming step. FIG. 11 is a partial cross-sectional view for explaining a schematic structure of a domain wall motion type device according to a modified example of the second embodiment of the present invention. FIG. 11 is a partial cross-sectional view for explaining a schematic structure of a domain wall motion type device according to a modified example of the second embodiment of the present invention. FIG. 13 is a schematic diagram illustrating a structure of a domain wall motion type device according to a third embodiment of the present invention, and corresponds to the partial cross-sectional view of FIG. 10 is a flowchart illustrating a method for manufacturing a domain wall motion type device according to a third embodiment of the present invention. 13A to 13C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a third embodiment of the present invention, and are partial cross-sectional views in a masking step. 13A to 13C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a third embodiment of the present invention, and are partial cross-sectional views in an insulating film etching step. 13A to 13C are schematic diagrams illustrating a method for manufacturing a domain wall motion type device according to a third embodiment of the present invention, and are partial cross-sectional views in a magnetic nanowire material film-forming step.

Below, the domain wall motion device and the manufacturing method thereof according to the present invention will be described with reference to the drawings. The domain wall motion device and its elements shown in the drawings may be exaggerated in size and positional relationship, and the shape and structure may be simplified, in order to clearly explain the device.

First Embodiment
1 and 2, the spatial light modulator (domain wall motion device) 50 according to the first embodiment of the present invention includes a substrate 71, a domain wall motion element 10 including a magnetic fine wire 1 and electrodes 21, 22 connected to the upper surfaces of both ends of the magnetic fine wire 1, arranged in parallel in the width direction of the magnetic fine wire 1 on the substrate 71, an insulating layer 82 filling the gap between the electrodes 21, 22 of the domain wall motion element 10, and a frame 6 sandwiched between the substrate 71 and the insulating layer 82 and surrounding the arranged domain wall motion element 10. The spatial light modulator 50 has a gap around the magnetic fine wire 1 of the domain wall motion element 10, and the side surface of the magnetic fine wire 1 and the inner side surface 6s of the frame 6 are exposed, and this gap is a non-oxidizing atmosphere isolated from the outside. In this specification, the fine wire direction of the magnetic fine wire 1 is appropriately referred to as the x direction, the fine wire width direction as the y direction, and the thickness direction as the z direction. In FIG. 2 and in the cross-sectional views described later, the cut surfaces are hatched (with a diagonal line pattern), and other areas (side surfaces behind the cut surfaces) are shown with a dot pattern or with only outlines (white).

The magnetic domain wall motion element 10 is a light modulation element in which the magnetic layer 11 (see FIG. 3) of the magnetic nanowire 1 has multiple pixels arranged in succession in the nanowire direction (x direction), and transmits or reflects light incident from above or below, and emits light whose polarization direction has been changed to a binary angle for each pixel. Therefore, a spatial light modulator 50 in which multiple magnetic domain wall motion elements 10 are arranged in the y direction is a transmission type or reflection type spatial light modulator with pixels arranged in a two-dimensional array (see Patent Documents 8 and 9). A pixel refers to a means for displaying information (bright/dark) in the smallest unit of display by the spatial light modulator. The spatial light modulator 50 has magnetic domain wall motion elements 10 arranged in parallel with a pitch of the length of one pixel (pixel length) in the y direction, the number of which is equal to the number of pixels in the y direction. For the sake of simplicity, eight magnetic domain wall motion elements 10 are shown in FIG. 1. As described below, the spatial light modulator 50 is manufactured by bonding a substrate 71 on which the magnetic nanowire 1 and frame 6 are formed, and another substrate (support substrate) on which the electrodes 21, 22 and insulating layer 82 are formed, at bonding surface B shown in FIG. 2.

(Magnetic domain wall motion element)
3, the domain wall motion element 10 includes the magnetic nanowire 1 and electrodes 21, 22 connected to the upper surfaces at both ends in the nanowire direction, and further includes a conductor (magnetic field application member) 3 spaced apart on the upper side near one end of the magnetic nanowire 1. In the spatial light modulator 50, an insulating layer 82 is provided between the magnetic nanowire 1 and the conductor 3. The magnetic nanowire 1 is formed into a nanowire shape by laminating a magnetic layer 11 made of a perpendicular magnetic anisotropy material and a channel layer 12 made of a topological insulator. In order to connect the electrodes 21, 22 to the channel layer 12, in the domain wall motion element 10, the magnetic nanowire 1 includes the channel layer 12 in an upper layer.

In this embodiment, the magnetic layer 11 and the channel layer 12 that constitute the magnetic nanowire 1 are each formed in a straight line with uniform thickness and width. The magnetic nanowire 1 is partitioned into a write region 1w and a display region 1a in the nanowire direction between the connection parts with the electrodes 21, 22. The write region 1w is a region in which a magnetic field is applied from the conductor 3 to selectively make the magnetization direction upward or downward, and is set to a length of one pixel or more in the nanowire direction. The display region 1a constitutes the display region of the spatial light modulator 50, and is a region in which pixels are continuous in the nanowire direction. The length of the display region 1a in the nanowire direction is set to the product of the pixel length and the number of pixels in the nanowire direction (x direction).

The magnetic layer 11 is a main component of the domain wall motion element 10, and the magnetization direction of a portion of the region indicates a desired direction, either upward or downward, and changes the polarization direction to a binary angle (+θ _k /-θ _k ) when transmitting or reflecting incident light due to the Faraday effect or Kerr effect. The magnetic layer 11 is made of a perpendicular magnetic anisotropy material formed in a fine line shape, and is divided in the fine line direction into two or more magnetic domains, one with the magnetization direction facing upward and the other with the magnetization direction facing downward.

The domain wall motion element 10 changes the desired polarization direction of light reflected by each pixel of the magnetic layer 11. For this purpose, the magnetic layer 11 is preferably made of a perpendicular magnetic anisotropy material having a relatively small coercive force, and more preferably has a high magneto-optical effect. A known magnetic material used in a magnetization free layer of a CPP-GMR (Current Perpendicular to the Plane Giant MagnetoResistance) element or a TMR (Tunnel MagnetoResistance) element applied to a magnetoresistance effect element of an MRAM or the like can be applied. Specifically, examples of the multilayer include a Co/Pd multilayer film in which transition metals such as Fe, Co, Ni, etc. and precious metals such as Pd, Pt are alternately and repeatedly laminated at a thickness ratio of about 1:2 to 4, a Co/Tb multilayer film in which transition metals and rare earth metals such as Tb are alternately and repeatedly laminated, alloys (RE-TM alloys) of rare earth metals and transition metals such as Tb-Fe-Co, Gd-Fe, etc., and L1 ₀ ordered alloys such as FePt, FePd, and CrPt _3. In this embodiment, a Co/Tb multilayer film or a Co/Pt multilayer film containing Co, into which Bi, etc. of the channel layer 12 is easily diffused, is particularly preferable.

The magnetic layer 11 is formed in a thin line shape that is sufficiently long with respect to the thickness and width. Furthermore, the smaller the cross-sectional area of the magnetic layer 11, which is the product of the thickness and width, the smaller the current supplied to the magnetic thin line 1 can be. On the other hand, the magnetic layer 11 preferably has a thickness and width so as to have a certain degree of coercive force to hold the magnetization, and the larger the thickness, the higher the optical modulation degree (the larger the Kerr rotation angle θ _k ). Specifically, the thickness is preferably 5 nm or more, and more preferably 10 nm or more. However, although it depends on the material, if the thickness of the magnetic layer 11 exceeds about 20 nm, the increase in the optical modulation degree slows down, and if the film becomes even thicker, it may be difficult to hold the perpendicular magnetic anisotropy. Furthermore, if the magnetic layer 11 is thick, the magnetic wall that separates the magnetic domains becomes difficult to move. Therefore, the magnetic layer 11 preferably has a thickness of 30 nm or less, and more preferably 20 nm or less. Furthermore, it is preferable that the thin line width is two times or less than the thin line direction length of one pixel. Furthermore, it is preferable that the pixels are wide, and although it depends on the wavelength of the incident light, it is preferable that the width of the magnetic nanowire 1 and the length of one pixel in the nanowire direction are about 200 to 300 nm or more.

The channel layer 12 is a path for passing electric current, is laminated on the upper surface of the magnetic layer 11, and is formed in the same shape as the magnetic layer 11 in planar (xy) view. The channel layer 12 is a thin film that generates a spin current by the spin Hall effect (SHE) when electric current flows through it, and is made of a topological insulator such as BiSb or BiSe that has a high SOT effect. The channel layer 12 preferably has a thickness of 1 nm or more, and preferably 10 nm or less.

The magnetic nanowire 1 may have a Ru film laminated on the channel layer 12 with a thickness of several atoms (not shown). Ru has the property of being deposited so as to penetrate into the gaps between the concaves and convexes, so that even an extremely thin film of Ru can flatten the concaves and convexes on the surface of the channel layer 12 made of a topological insulator, and smooth the junction surface between the magnetic nanowire 1 and the electrodes 21 and 22. The Ru film has a thickness of several atoms, and is preferably 0.2 to 3 nm. The magnetic nanowire 1 may also have an undercoat film under the magnetic layer 11 to ensure adhesion to the substrate 71. The undercoat film may be made of a nonmagnetic metal material such as Ru, Ta, Cu, Pt, Au, or W, or an insulating film such as MgO, SiO ₂ , or SiN, and is preferably 1 to 10 nm thick.

The electrodes 21 and 22 are terminals for supplying a current from the outside to the magnetic nanowire 1 in the nanowire direction (+x direction or -x direction) to move the domain wall of the magnetic layer 11. For this purpose, the electrodes 21 and 22 are connected to the channel layer 12 (or via a Ru film) at both ends of the magnetic nanowire 1. In the present invention, the electrodes 21 and 22 are not formed as films on the magnetic nanowire 1, but are formed on a substrate (second substrate, support substrate 73) other than the substrate 71, and then bonded to the magnetic nanowire 1, as described later. For this purpose, it is preferable to use Au, Cu, W, Al, Ag, or an alloy thereof among the metal electrode materials for the electrodes 21 and 22, and Au is particularly preferable. The electrodes 21 and 22 may also have a barrier film made of Ta, TaN, Ti, TiN, TiW, or the like at the interface with the portion of the insulating layer 82 made of SiO ₂ . However, since it is difficult to sufficiently smooth the bonding surface B before bonding during the manufacture of the spatial light modulator 50, it is preferable that no barrier film is provided on the bonding surface B. The electrodes 21 and 22 preferably have a thickness of 50 nm or more, and are formed to a thickness and width corresponding to the magnitude of the current supplied to the magnetic nanowire 1. The electrodes 21 and 22 may also have a structure of two or more layers made of different metal electrode materials, with Au or the like being applied to the layer bonded to the magnetic nanowire 1, and other than the above metal electrode materials, general metal electrode materials such as Ta, Cr, Pt, Pd, Ru, and alloys thereof can be applied.

The conductor 3 is a magnetic field application means that selectively applies a magnetic field in an upward or downward direction to the magnetic layer 11 in a predetermined partial region (write region 1w) in the thin line direction. By passing a current through the conductor 3 in the thin line width direction (+y direction or -y direction) of the magnetic fine wire 1, an upward or downward magnetic field is generated in the magnetic layer 11. Therefore, the conductor 3 is formed in a thin line shape in the y direction with a thickness and width corresponding to the magnitude of the current that generates a magnetic field that reverses the magnetization of the magnetic layer 11, and is placed directly above or below the write region 1w of the magnetic fine wire 1. The conductor 3 can be made of the general metal electrode materials listed as the materials for the electrodes 21 and 22, and may be made of the same material as the electrodes 21 and 22. In order to apply a stronger electric field to the magnetic layer 11, it is preferable that the distance between the conductor 3 and the magnetic layer 11 is short to the extent that no leakage current flows through the magnetic fine wire 1. The conductor 3 may be disposed on either the top or bottom side of the magnetic nanowire 1, and in this embodiment, it is disposed on the same top side as the electrodes 21 and 22. Therefore, an insulating layer 82 is provided between the conductor 3 and the magnetic nanowire 1. In the spatial light modulator 50 according to this embodiment, all the domain wall motion elements 10 can share the conductor 3, that is, the conductor 3 is provided so as to cross all the magnetic nanowires 1. In addition, in order to generate a magnetic field that is strong relative to the magnitude of the current, it is preferable to provide two conductors 3 arranged side by side in the thin-line direction (x direction) of the magnetic nanowire 1, as shown in FIG. 2 and FIG. 3. In order to pass currents in the opposite directions to each other, in FIG. 1, these two conductors 3 are formed into one bent in a hairpin shape outside the region where the magnetic nanowires 1 of the spatial light modulator 50 are arranged side by side.

The substrate 71 is a base that supports the magnetic nanowire 1, and further, together with the insulating layer 82 and the frame 6 described later, seals the magnetic nanowire 1 inside to isolate it from the external environment. The substrate 71 can be made of a known substrate material that has heat resistance to the temperature during the formation of the magnetic nanowire 1 (photolithography, deposition of the magnetic layer 11 and the channel layer 12). At least the surface (the surface on which the magnetic nanowire 1 is formed) of the substrate 71 is an insulator, and in the case of a conductor such as a metal, an insulating film is formed on the surface, which is listed as a material for the insulating layer 82 described later. In addition, as described later, the substrate 71 on which the magnetic nanowire 1 is formed is bonded to the support substrate 73 on which the electrodes 21 and 22 are formed, so that the thickness of the substrate 71 is sufficient to provide sufficient strength. The substrate 71 may have a planar shape that is equal to or larger than the outer shape of the frame 6, and is rectangular in FIG. 1, but is not particularly limited thereto. In addition, the substrate 71 has a sufficiently smooth surface in order to smooth the surface of the magnetic nanowire 1 formed thereon. When the spatial light modulator 50 is a transmission type spatial light modulator or a reflection type spatial light modulator in which the substrate 71 side is the light incident/exit surface, a transparent substrate is applied to the substrate 71. Specifically, examples of the substrate include _SiO2 (silicon oxide, glass), soda glass, MgO (magnesium oxide), sapphire, and GGG (gadolinium gallium garnet) single crystal substrates, as well as various transparent plastic substrates. When the spatial light modulator 50 is a reflection type spatial light modulator in which the side to which the electrodes 21 and 22 of the magnetic nanowire 1 are connected is the light incident/exit surface, the substrate 71 can be, in addition to the transparent substrate, a silicon substrate with a thermally oxidized surface or a metal substrate with an insulating film formed on the surface.

The insulating layer 82 is provided on the support substrate 73 together with the electrodes 21 and 22, and the periphery of the electrodes 21 and 22 is flush with the surface of the electrodes 21 and 22. Therefore, the upper surface of the magnetic nanowire 1 is bonded to the insulating layer 82 except for the region connected to the electrodes 21 and 22. The insulating layer 82 is also bonded to the frame 6 described later. The insulating layer 82 can widen the bonding area in the spatial light modulator 50. The insulating layer 82 can be made of known inorganic insulating materials provided in semiconductor elements such as oxide films such as SiO ₂ , Al ₂ O ₃ , and MgO, SiOC (carbon-added silicon oxide), Si nitride (SiN), and AlN, and may have a structure of two or more layers made of different materials. In this embodiment, the insulating layer 82 is preferably made of Si oxide such as SiO ₂ or SiOC, which is easy to process the surface to be smooth by CMP or the like, or a Si compound based on the same, and is preferably applied at least to a thickness of about 1 μm from the surface (the bonding surface with the magnetic nanowire 1).

The frame 6 is sandwiched between the substrate 71 and the insulating layer 82, and together with these, seals the magnetic fine wire 1 inside, and also increases the bonding area in the spatial light modulator 50 to increase the bonding strength. The frame 6 is formed on the substrate 71 at the same time as the magnetic fine wire 1 using the same material, and therefore has the same thickness as the magnetic fine wire 1. The frame 6 has a rectangular frame shape in FIG. 1, but there are no particular limitations on its shape as long as it surrounds the magnetic fine wires 1 arranged side by side in the spatial light modulator 50. The frame 6 is designed to have a frame width that can seal the magnetic fine wire 1 and provide sufficient strength for bonding to the insulating layer 82.

[Method of manufacturing spatial light modulator]
4, the method for manufacturing the spatial light modulator (domain wall motion device) according to the first embodiment of the present invention sequentially includes a masking step S22 for forming a mask on a substrate 71 (first substrate) with an area for forming the magnetic nanowire 1 and the frame 6, a magnetic nanowire material deposition step S24 for sequentially depositing the material of the magnetic layer 11 of the magnetic nanowire 1 and the material of the channel layer 12 on the substrate 71, a lift-off step S25 for removing the mask at 90° C. or less, and a substrate bonding step S4 for bonding a support substrate (second substrate) 73 on which the electrodes 21 and 22, the conductive wire 3, and the insulating layer 82 are formed to the substrate 71 at 90° C. or less so that the electrodes 21 and 22 are bonded to the magnetic nanowire 1. In this embodiment, further, an electrode substrate forming step S3 for forming the electrodes 21 and 22, the conductive wire 3, and the insulating layer 82 on the support substrate 73 is performed before the substrate bonding step S4, and a substrate removing step S5 for removing the support substrate 73 is performed after the substrate bonding step S4. The method for manufacturing the spatial light modulator according to this embodiment is performed so that the temperature after the magnetic nanowire 1 is formed (S24) does not exceed 90° C. It is preferably performed at 80° C. or less, more preferably 50° C. or less, and even more preferably at room temperature.

In this embodiment, on the substrate 71, the surfaces of the frame 6 and the magnetic nanowire 1 are formed to be flat and smooth on the same plane, and no parts protrude above the plane. On the substrate 71, this plane becomes the bonding surface B. On the support substrate 73, the electrodes 21, 22 and the insulating layer 82 form the entire surface (the upper surface with the support substrate 73 facing downward) to be flat and smooth, becoming the bonding surface B. Each process will be described in detail below with reference to Figures 5A to 5C, Figures 6A to 6B, and Figure 7. Note that Figures 5A to 5C and Figures 6A to 6B show end views of the cut portion.

(Electrode substrate forming process)
In the electrode substrate forming step S3, the electrodes 21 and 22 are formed in their respective predetermined regions on the support substrate 73, an insulating layer 82 is formed in the remaining regions, and the entire surface is made flat and smooth. For this purpose, the electrode substrate forming step S3, for example, sequentially executes the insulating film forming step S31 for forming an insulating film that forms the insulating layer 82 on the support substrate 73, the masking step S32 for forming a mask that leaves open the regions where the electrodes 21 and 22 are to be formed, the insulating film etching step S33 for etching the insulating film, the mask removing step S34 for removing the mask, the electrode material forming step S35 for forming a film of a metal electrode material that forms the electrodes 21 and 22, and the smoothing step S36. In this embodiment, the conductor 3 is further formed to be thinner than the electrodes 21 and 22 so that it is not exposed on the surface, i.e., is covered with the insulating layer 82. For this purpose, the electrode substrate forming step S3 repeats steps S31 to S35 twice. The electrodes 21, 22 and the conductive wire 3 can be formed by a known method such as electroplating, electroless plating, sputtering, printing, etc., depending on the material, thickness, and pattern shape, and are formed by plating here. When the insulating layer 82 is formed of _SiO2 , for example, it can be formed by a CVD (Chemical Vapor Deposition) method.

The support substrate 73 is a base for forming the electrodes 21, 22, the conductive wire 3, and the insulating layer 82 during the manufacture of the spatial light modulator 50. The support substrate 73 can be made of any of the known substrates listed as materials for the substrate 71. However, since the support substrate 73 is removed in the substrate removal step S5 and is not provided in the spatial light modulator 50, the surface (the surface on which the electrodes 21, 22, etc. are formed) does not have to be an insulator, and for example, a metal plate can be used. In addition, it is preferable to use a substrate material for the support substrate 73 that is compatible with the removal method in the substrate removal step S5.

In the electrode substrate forming step S3, first, a metal film is formed on the support substrate 73 by sputtering or the like to form a seed layer 2s. If the support substrate 73 is a metal plate, the seed layer is not necessary. Next, an insulating film (e.g., SiO ₂ , indicated by the reference symbol "82'" in the figure) that forms the insulating layer 82 is formed on the seed layer 2s to a thickness greater than that of the conductor 3 (S31). Then, a mask is formed by photolithography to leave open the regions in which the electrodes 21, 22 and the conductor 3 are to be formed (S32), and the insulating film is removed by etching (S33) to expose the seed layer 2s (FIG. 5A). Next, a metal electrode material (e.g., Au) that forms the electrodes 21, 22 is formed to the thickness of the conductor 3 by electroplating in the regions where the seed layer 2s is exposed, and the conductor 3 and the electrodes 21, 22 are formed to the same thickness as the conductor 3 (indicated by the reference symbols "21'" and "22'" in the figure) (S35, FIG. 5B). In a second insulating film forming step S31, an insulating film is formed thereon so that the total thickness of the insulating film and the first film formation is greater than the thickness of the electrodes 21, 22. In a second masking step S32, a mask is formed leaving only the areas where the electrodes 21, 22 are to be formed open, and in an insulating film etching step S33, the insulating film on the plating films 21', 22' is removed (FIG. 5C). In an electrode material forming step S35, a metal electrode material is further formed by electroplating, electroless plating, sputtering, or the like in the areas where the plating films 21', 22' are exposed so that the total thickness of the metal electrode material is greater than the thickness of the electrodes 21, 22.

In the smoothing step S36, the surfaces of the electrodes 21, 22 and the insulating layer 82, which are the bonding surfaces of the support substrate 73, are planarized and smoothed. The surfaces are ground by CMP (Chemical Mechanical Polishing) so that the Au and insulating film have a predetermined thickness (the thickness of the electrodes 21, 22), and are further polished to be planarized and smoothed. For example, when the bonding method in the substrate bonding step S4 is surface activated bonding (SAB), it is preferable that the arithmetic mean roughness Ra of the surface is 1 nm or less. Also, as described below, when a Si film is bonded as an adhesive layer, it is preferable that the arithmetic mean roughness Ra of the surface before the Si film is formed is 1 nm or less.

(Mask process, magnetic nanowire material deposition process, lift-off process)
In the masking step S22, a mask PR2 is formed on the substrate 71 by photolithography using a photoresist for lift-off, with the region in which the magnetic nanowire 1 and the frame 6 are to be formed being left open (FIG. 6A). The photoresist to be used is a type that can be removed without ashing, such as a solvent-soluble type. In the magnetic nanowire material deposition step S24, a magnetic material for forming the magnetic layer 11 of the magnetic nanowire 1 and a topological insulator for forming the channel layer 12 are deposited in order on the substrate 71 by sputtering from above the mask PR2, and embedded in the grooves of the mask PR2 (FIG. 6B). In the lift-off step S25, the mask PR2 is dissolved and removed using a solvent such as N-methyl-2-pyrrolidone (NMP) that corresponds to the resist that forms the mask PR2. At this time, the liquid temperature of the solvent is set to 90° C. or less. Through the series of steps S22, S24, and S25 (which will be referred to as magnetic nanowire substrate forming step S2 as appropriate), the magnetic nanowire 1 and the frame body 6 are formed on the substrate 71 at a uniform height.

(Substrate bonding process)
In the substrate bonding step S4, the substrate 71 and the support substrate 73 are bonded together with their back surfaces facing outward, and the magnetic fine wire 1 on the substrate 71 is bonded to the electrodes 21, 22 and the insulating layer 82 on the support substrate 73, and the frame 6 on the substrate 71 is bonded to the insulating layer 82 (FIG. 7). In order to suppress damage to the magnetic fine wire 1 due to heat, it is preferable to bond the substrates at room temperature without pressure or with a low pressure close to this pressure. As such a bonding method, a known method for hybrid bonding of semiconductor element substrates can be applied. For example, surface activation bonding is used, in which the surfaces of the substrates 71, 73 (the magnetic fine wire 1 and the frame 6, the electrodes 21, 22, and the insulating layer 82) are irradiated with ions or plasma of the inert gas in an inert gas atmosphere to activate the surfaces, and the activated surfaces are brought into contact with each other to bond the substrates.

Alternatively, a Si film can be bonded as an adhesive layer (Masahide Goto et al., "Multilayer Technology for Pixel-Parallel Signal Processing Image Sensors Using Room-Temperature Wafer Bonding," Abstracts of Lectures Commemorating the 70th Anniversary of the Founding of the Institute of Image Information and Television Engineers, 32E-2, 2020). The Si film is provided on either or both of the bonding surface of the substrate 71 (on the magnetic nanowire 1 and frame 6) and the bonding surface of the support substrate 73 (on the electrodes 21, 22 and insulating layer 82). When forming a Si film on the substrate 71, it can be formed following the material of the magnetic nanowire 1 in the magnetic nanowire material film formation step S24. When forming a Si film on the support substrate 73, the Si film is formed by sputtering or the like after the smoothing step S36. The thickness of the Si film is preferably 3 nm or more, while it is less than 10 nm so as not to cause poor connection near the bonding surface B, and when the Si film is provided on both the substrate 71 and the support substrate 73, the total thickness is less than 10 nm. If the Si film is less than 10 nm thick, the electrodes 21 and 22 penetrate and connect to the magnetic nanowire 1 (channel layer 12).

(Substrate removal process)
In the substrate removal step S5, the support substrate 73 is removed, and if a seed layer 2s is formed, this is also removed to expose the electrodes 21, 22, the insulating layer 82, and the conductive wire 3. The support substrate 73 can be removed by a known method such as peeling. By the above procedure, the spatial light modulator 50 can be manufactured while reducing damage to the magnetic nanowire 1. Note that, when the magnetic layer 11 is made of a material that is easily oxidized such as an RE-TM alloy, it is preferable to perform the steps from the magnetic nanowire material deposition step S24 to the substrate bonding step S4 in a non-oxidizing atmosphere such as a vacuum or an inert gas atmosphere.

In the electrode substrate forming step S3, the seed layer _2s can be formed on the entire surface including the support substrate 73 (bottom surface of holes and grooves) and the step of the insulating film after etching the insulating film (S33) rather than before forming the insulating film (SiO 2 ) (S31). Alternatively, in the electrode material film forming step S35, Au can be formed by electroless plating. In these cases, the Au film is formed on the entire surface including the surface of the patterned insulating film by plating, and then the Au film is ground by CMP to expose the insulating film. Alternatively, a mask can be formed on the seed layer 2s formed on the entire surface of the support substrate 73 (S32), Au is formed by electroplating (S35), and the mask is removed (S34), and then the seed layer 2s in the region without the plating film can be removed by etching the entire surface. Through these steps, the conductor 3 and the electrodes 21 and 22 are formed on the support substrate 73 to the same thickness as the conductor 3. Next, on the support substrate 73, a _SiO2 film is formed on the plating film (Au) to a thickness greater than that of the insulating layer 82 and the electrodes 21, 22 (S31). Then, steps S32, S33, S34, and S35 are carried out in order to remove the _SiO2 in the areas where the electrodes 21, 22 are to be formed, to expose the Au, and the Au film is formed by electroless plating so that the thickness of the Au film combined with the previous plating film is greater than that of the electrodes 21, 22. Thereafter, in a smoothing step S36, the surface is ground and polished so that the Au and _SiO2 have the thickness of the electrodes 21, 22.

[Operation of spatial light modulator]
(Writing method)
In the magnetic domain wall motion element 10, the magnetic layer 11 is formed into a magnetic domain having a predetermined magnetization direction, either upward or downward, by a magnetic field from the conductor 3 connected to the magnetic field application current source in the writing region 1w of the magnetic nanowire 1, and then the magnetic domain is moved to a pixel having a predetermined x address in the display region 1a by a direct current I _m supplied to the magnetic nanowire 1 from the magnetic domain movement current source connected to the electrodes 21 and 22. The magnetic field application current source is connected to both ends of the conductor 3 to supply a direct current and switch the polarity. In this embodiment, the magnetic domain wall motion element 10 is an SOT type magnetic domain wall motion element, and the magnetic domain wall of the magnetic layer 11 moves in the same direction as the current supplied to the magnetic nanowire 1. Therefore, the positive (+) pole of the magnetic domain movement current source is connected to the electrode 21 on the writing region 1w side, and the negative (-) pole is connected to the electrode 22. The higher the current density in the magnetic nanowire 1, the faster the magnetic domain wall moves. The magnetic nanowire 1 is preferably supplied with a pulsed current rather than a continuous current, and is set so that the magnetic wall moves by the pixel length with one pulse or a predetermined number of pulses, which is set as one pulse here. Therefore, it is preferable to use a DC pulse power supply as the magnetic domain movement current source. Then, during the stop period of the pulsed current, the magnetic field application current source supplies a current to the conductor 3 to apply a magnetic field to the writing area 1w. By alternately repeating the writing of one pixel based on data "1" and "0" input in the order of x addresses and the movement of the magnetic wall in the magnetic layer 11 by the pixel length, all the pixels in the display area 1a of the magnetic layer 11 can be magnetized in the desired direction. Here, data "1" is set to the upward magnetization direction, and data "0" is set to the downward magnetization direction.

In the spatial light modulator 50 according to the present embodiment, all the domain wall motion elements 10 share the conductor 3 as a magnetic field application means, and the magnetization direction of the magnetic layer 11 in the writing region 1w of each magnetic nanowire 1 is made to be the same. Therefore, in the spatial light modulator 50, the magnetic field application current source is connected to the conductor 3, and the magnetic domain motion current source is connected to each electrode 21 or electrode 22 of the domain wall motion elements 10 via a switch, so that the connection/disconnection can be switched for each domain wall motion element 10 (see Patent Document 9). In such a spatial light modulator 50, for example, in a first step, the magnetic field application current source supplies a current + _Iw to the conductor 3, which applies a magnetic field to the magnetic layer 11 in an upward direction. In a second step, the magnetic domain motion current source supplies one pulse of current _{Im to the magnetic nanowire 1 of the domain wall motion element 10 corresponding to the y address where the data of the first x address is "1". In a third step, the magnetic field application current source supplies a current -Iw to} the conductor 3, with the polarity reversed from that in the first step. In the fourth step, the magnetic domain movement current source supplies one pulse of current I _m to all magnetic nanowires 1 to which no current was supplied in the second step. By the first to fourth steps, data is written at the first x address in all y addresses. By repeating the same process, data is written at all x addresses.

(Optical modulation operation)
The light modulation operation of the spatial light modulator 50 according to this embodiment is the same as that of a conventional magneto-optical spatial light modulator. That is, light that has been made into one polarized component by passing through a polarizing filter or the like is incident as incident light into the region (pixel array) of the spatial light modulator 50 in which the display region 1a of the magnetic nanowire 1 is arranged. The incident angle is most preferably 0° (z direction), and is preferably closer. Then, the light that has passed through or been reflected by the magnetic nanowire 1 and is emitted from the spatial light modulator 50 is made incident on a polarizing filter (analyzer) arranged so that the polarized component rotated at an angle of +θ _k or −θ _k with respect to the polarized component of the incident light is the absorption axis. The light that has passed through this polarizing filter is light that is emitted only from either a pixel in which data "1" is written or a pixel in which data "0" is written.

(Modification)
In order to facilitate the magnetic domain walls at the boundaries between pixels in the display region 1a, the magnetic nanowire 1 may be formed with a constriction so as to narrow the width slightly, or may be bent in an alternating zigzag shape by bending in opposite directions (see Patent Document 8). In addition, in the spatial light modulator 50 according to this embodiment, the magnetic nanowire 1 may be arranged in a straight line or in the above-mentioned shape, and parallel to each other, at least in the display region 1a, so that the pixels are arranged two-dimensionally. Therefore, the magnetic nanowire 1 may be bent or curved on both sides of the display region 1a so that the interval between the adjacent magnetic nanowires 1 is widened, and the interval between the joints with the electrodes 21 and 22 at both ends may be widened, and the ends may be formed wider. Note that the bending angle and curvature of the magnetic nanowire 1 are designed within a range that does not interfere with the magnetic domain wall movement in the magnetic layer 11 from the writing region 1w to the display region 1a. With this configuration, the accuracy of alignment in the substrate bonding step S4 can be kept low with respect to the pixel length in the y direction. Alternatively, the gap may be widened only on one end side of the magnetic nanowire 1 (eg, the electrode 21 side), and the electrode 22 on the other end side may be formed in a straight line in the y direction crossing all the magnetic nanowires 1 for common use.

In addition, the domain wall motion element 10 may have the conductor 3 disposed on the substrate 71 side of the magnetic nanowire 1, and for this purpose, prior to the masking step S22 (magnetic nanowire substrate forming step S2), the conductor 3 and an insulating layer 81 covering it are formed on the substrate 71 (see the second embodiment shown in FIG. 8) to flatten the surface of the insulating layer 81, and the magnetic nanowire 1 and frame 6 are formed on top of it. Alternatively, the conductor 3 may not be formed on the substrate 71 or the support substrate 73, and after the substrate joining step S4 or the substrate removal step S5, a further insulating substrate on which the conductor 3 is formed may be joined.

The spatial light modulator 50 may have a substrate 72 on which at least the surface (the surface on which the electrodes 21, 22, etc. are formed) is an insulator on the electrodes 21, 22, the conductor 3, and the insulating layer 82 (see FIG. 8). The substrate 72 may be made of any of the known substrates listed as the material for the substrate 71. For this purpose, in the electrode substrate formation step S3, the electrodes 21, 22, etc. are formed on the substrate 72 instead of the support substrate 73, and the electrodes 21, 22 and the conductor 3 are formed without forming a seed layer 2s between the substrate 72 and the insulating layer 82, and the substrate removal step S5 is not performed. In this case, the electrodes 21, 22 are extended to the end of the substrate 72 to enable connection to a current source for magnetic domain movement, and the extended portions are embedded in the insulating layer 82 in the same manner as the conductor 3 so as not to be connected to the frame 6. For this purpose, in the electrode substrate forming process S3, a mask is formed in the first masking process S32, leaving open the area where the extended electrodes 21, 22 are to be formed together with the area where the conductor 3 is to be formed, and the plating films 21', 22' (FIG. 5B) are formed in the extended pattern in the first electrode material film forming process S35. Alternatively, an insulating substrate is applied to the substrate 72, and through holes are formed from the rear surface (outer surface) thereof to expose the electrodes 21, 22. The through holes can be formed in the substrate 72 before or after the substrate bonding process S4, or before the electrode substrate forming process S3, and furthermore, a metal electrode material can be embedded in the through holes and the electrodes 21, 22 can be formed thereon.

The spatial light modulator 50 according to the present embodiment may include a magnetic field application member 3 for each domain wall motion element 10. The magnetic field application member 3 for each domain wall motion element 10 is, for example, a known magnetic recording head structure in which thin film coils are stacked. For this purpose, it is preferable that the spatial light modulator 50 is arranged with sufficient spacing between the magnetic nanowires 1 at least in the writing region 1w. Alternatively, the magnetic field application member 3 may further include a magnetic shield made of a magnetic material between the adjacent domain wall motion elements 10. Since such a spatial light modulator 50 can simultaneously write desired data for each domain wall motion element 10, a current I _m may be simultaneously supplied to all the magnetic nanowires 1 to move the domain walls (see Patent Document 8), which can shorten the writing time to the pixel array and further share the electrodes 21 and 22.

Moreover, the domain wall motion element 10 may be an STT type domain wall motion element in which the magnetic nanowire 1 does not include the channel layer 12. Such a magnetic nanowire 1 may have a protective film of about 1 to 10 nm in thickness on the magnetic layer 11, the protective film being made of a nonmagnetic metal material such as Ru, Ta, Cu, Pt, Au, or W. In the STT type, the domain wall of the magnetic layer 11 moves in the opposite direction to the current I _m supplied to the magnetic nanowire 1, so the negative pole of the magnetic domain motion current source is connected to the electrode 21, and the positive pole is connected to the electrode 22.

Second Embodiment
The domain wall motion element of the domain wall motion type device according to the first embodiment of the present invention can be configured as a magnetoresistance effect element by laminating an insulating film and a magnetic film with perpendicular magnetic anisotropy on the magnetic layer of the magnetic nanowire. Therefore, the domain wall motion type device can be a racetrack memory. In addition, in the manufacturing method of the domain wall motion type device, even if the periphery of the electrode of the domain wall motion type device is not filled with an insulating layer, the electrode and the magnetic nanowire can be joined and the periphery of the magnetic nanowire can be isolated from the outside. Hereinafter, the configuration of the domain wall motion type device according to the second embodiment of the present invention will be described with reference to FIGS. 8 and 9. The same elements as those in the first embodiment (see FIGS. 1 to 7) are given the same reference numerals and will not be described.

8, the magnetic memory (domain wall motion device) 50A according to the second embodiment of the present invention includes a substrate 71, a domain wall motion element 10A including a magnetic fine wire 1 and electrodes 21, 22 connected to the upper surface at both ends thereof, arranged in parallel on the substrate 71 in the direction of the fine wire width of the magnetic fine wire 1, an insulating layer 81 formed between the substrate 71 and the magnetic fine wire 1, a substrate (insulating layer) 72 on the electrodes 21, 22 of the domain wall motion element 10A, and a frame 6A sandwiched between the insulating layer 81 and the substrate 72 and surrounding the arranged domain wall motion element 10A. The external appearance of the magnetic memory 50A according to this embodiment is the same as that of the domain wall motion device 50 shown in FIG. 1, except that the substrate 72 is provided instead of the insulating layer 82, the insulating layer 81 is laminated on the substrate 71, and the conductor 3 is disposed below the magnetic fine wire 1 and embedded in the insulating layer 81. The magnetic memory 50A has a gap around the domain wall motion element 10A, and the top and side surfaces of the magnetic nanowire 1 except for the connection portion with the electrodes 21 and 22, the side surfaces of the electrodes 21 and 22, and the inner side surface 6s of the frame body 6A are exposed, and this gap is a non-oxidizing atmosphere that is isolated from the outside. The domain wall motion element 10A is a memory element in which the magnetic layer 11 (see FIG. 9) of the magnetic nanowire 1 has multiple memory cells continuously arranged in the nanowire direction (x direction). Therefore, the magnetic memory 50A in which multiple domain wall motion elements 10A are arranged in the y direction is a racetrack memory (see Patent Documents 5 to 7). As described later, the magnetic memory 50A is manufactured by bonding a substrate 71 on which the magnetic nanowire 1 and the insulating layer 81 etc. are formed, and a substrate 72 on which the electrodes 21 and 22 etc. are formed, at the bonding surface B shown in FIG. 8.

(Magnetic domain wall motion element)
9, the domain wall motion element 10A includes a magnetic nanowire 1 and electrodes 21, 22 connected to the upper surfaces at both ends in the nanowire direction, and a conductor (magnetic field application member) 3 spaced apart on the lower side near one end of the magnetic nanowire 1. The domain wall motion element 10A further includes a magnetoresistance effect element (magnetic detection means) 4 and an electrode 43 connected to its lower surface near the other end of the magnetic nanowire 1. As in the first embodiment, the magnetic nanowire 1 is formed in the shape of a nanowire by forming a magnetic layer 11 made of a perpendicular magnetic anisotropy material and a channel layer 12 made of a topological insulator laminated thereon.

In the domain wall motion element 10A, the magnetic nanowire 1 is partitioned in the nanowire direction between the connection parts with the electrodes 21 and 22 in the order of the write area 1w, the memory area 1a, and the read area 1r. As in the first embodiment, the write area 1w is an area in which a magnetic field is applied from the conductor 3 to selectively make the magnetization direction upward or downward, and is set to a length equal to or greater than the length of one memory cell (cell length) in the nanowire direction. The memory area 1a corresponds to the display area 1a of the spatial light modulator 50, and is an area in which memory cells are continuous in the nanowire direction. Therefore, the length of the memory area 1a in the nanowire direction is set to the product of the cell length and the number of bits in the nanowire direction (x direction). The read area 1r is an area for detecting the magnetization direction in this area of the magnetic layer 11, in which the magnetoresistance effect element 4 is provided, and the length of the nanowire direction is set to be equal to or less than the cell length. In detail, a barrier layer 42 and a magnetization fixed layer 41 are laminated on the lower surface (magnetic layer 11) of the magnetic nanowire 1 in that order from the magnetic layer 11 side, and an electrode 43 is further connected to the lower surface of the magnetization fixed layer 41.

The rest of the configuration of the magnetic nanowire 1 is as described in the first embodiment. However, it is preferable that the magnetic layer 11 does not need to have a magneto-optical effect, but has a certain degree of coercive force. The magnetic layer 11 may have a thickness and width that are necessary for maintaining magnetization and for thermal disturbance resistance, and more specifically, the thickness is preferably 5 nm or more and the width is preferably 10 nm or more. Similarly, the cell length is preferably 10 nm or more and 1/2 or more of the nanowire width. It is also preferable that the magnetic layer 11 has a width of 300 nm or less, since this makes it difficult for the magnetic domains to be divided in the width direction.

The magnetization pinned layer 41 and the barrier layer 42, together with the magnetic layer 11 in the read area 1r, constitute a TMR element consisting of a three-layer laminate structure, and are provided to detect the magnetization direction in the read area 1r of the magnetic layer 11 as data reading of the domain wall motion element 10A. That is, the read area 1r of the magnetic layer 11 becomes the magnetization free layer of the TMR element. The magnetization pinned layer 41 and the barrier layer 42, together with the magnetic layer 11 that becomes the magnetization free layer, may be of a material and shape suitable for a TMR element. In addition, the magnetization pinned layer 41 may be formed long and protruding outward from the magnetic nanowire 1 in the nanowire width direction (y direction) as long as it does not short-circuit with the magnetization pinned layer 41 of another domain wall motion element 10A. The magnetization pinned layer 41 has a magnetization direction fixed upward or downward. Therefore, the magnetic pinned layer 41 preferably has a coercive force equal to or greater than that of the magnetic layer 11. For this purpose, the magnetic pinned layer 41 can be made of a known perpendicular magnetic anisotropy material, similar to the magnetic layer 11, and is preferably made of a material used for the magnetic pinned layer (reference layer) of a CPP-GMR element or a TMR element. However, the magnetic pinned layer 41 is made of a material that is heat resistant to the processing temperature (baking temperature) in the photolithography (mask step S22) for forming the magnetic nanowire 1. The magnetic pinned layer 41 preferably has a thickness equal to or greater than that of the magnetic layer 11. The barrier layer 42 is an insulating film of the barrier layer of a known TMR element, and is preferably made of MgO, and is preferably less than 3 nm thick. The barrier layer 42 is provided at least between the magnetic layer 11 and the magnetic pinned layer 41, i.e., in the read area 1r, and may be provided on the entire lower surface of the magnetic layer 11, for example.

Electrode 43 is a terminal that is paired with electrode 21 or electrode 22 and supplies a data read current from the outside to magnetoresistance effect element 4 in a direction perpendicular to the film surface (+z direction or -z direction). For this purpose, electrode 43 is connected to the lower surface of magnetization fixed layer 41 of magnetoresistance effect element 4, and in this embodiment, it is extended to one end of the thin line direction of magnetic memory 50A (electrode 22 side) in order to connect to an external current source. Like conductor 3, electrode 43 can be formed from a known metal electrode material.

The conductor 3 has the same configuration as in the first embodiment, but in this embodiment, it is provided below the magnetic nanowire 1. Furthermore, by using the same metal electrode material and thickness as the electrode 43, the conductor 3 can be formed simultaneously with the electrode 43 during the manufacture of the magnetic memory 50A, as described below.

The substrate 72 is a base for forming the electrodes 21, 22 and the frame body 6A during the manufacture of the magnetic memory 50A, and furthermore, together with the substrate 71 and the frame body 6A, the magnetic fine wire 1 is sealed inside to protect it from the external environment. The substrate 72 can be made of any of the known substrates listed as materials for the substrate 71. The electrodes 21, 22 and the frame body 6A may be provided on an insulating layer 82 rather than directly on the substrate 72. Furthermore, in order to connect the electrodes 21, 22 to the outside of the magnetic memory 50A, hierarchical wiring may be provided and connected to the electrodes 21, 22 through through holes formed in the insulating layer 82.

The insulating layer 81 is provided on the substrate 71, and embeds the magnetization pinned layer 41 and barrier layer 42 of the magnetoresistance effect element 4, the electrode 43, and the conductor 3 to flatten the bottom surface of the magnetic nanowire 1 (magnetic layer 11). The insulating layer 81 can be made of any of the known inorganic insulating materials listed as the material for the insulating layer 82, and may have a structure of two or more layers of different materials. For example, when the magnetization pinned layer 41 is made of a material that is easily oxidized, such as an RE-TM alloy, it is preferable to apply a non-oxide such as SiN or MgO to the portion (layer) that contacts the side surface. On the other hand, as will be described later in the manufacturing method, when a smoothing process is performed by CMP together with the electrode 43, it is preferable to apply SiO ₂ or SiOC to this layer.

The frame body 6A is sandwiched between the insulating layer 81 and the substrate 72, and together with these, seals the magnetic nanowire 1 and the electrodes 21, 22 inside, and also increases the bonding area in the magnetic memory 50A. The shape of the frame body 6A is the same as that of the frame body 6. The frame body 6A is formed by bonding a frame body (first layer) 61 formed on the insulating layer 81 at the same time as the magnetic nanowire 1 and made of the same material, and a frame body (second layer) 62 formed on the substrate 72 at the same time as the electrodes 21, 22 and made of the same material. Therefore, the frame body 61 has the same structure as the frame body 6 in the first embodiment. The frame bodies 61 and 62 may be of the same or different shapes in a plan view, and may have a bonding area that provides sufficient bonding strength.

[Method of manufacturing magnetic memory]
As shown in Figure 10, a manufacturing method for a magnetic memory (domain wall motion device) according to the second embodiment of the present invention sequentially includes a masking process S22 for forming a mask on a substrate (first substrate) 71, leaving open areas for the magnetic wire 1 and frame body 6A to be formed, a magnetic wire material deposition process S24 for sequentially depositing the material of the magnetic layer 11 of the magnetic wire 1 and the material of the channel layer 12 on the substrate 71, a lift-off process S25 for removing the mask, and a substrate bonding process S4 for bonding a substrate (second substrate) 72, on which electrodes 21, 22 and frame body 62 have been formed, to the substrate 71 at 90°C or less so that the electrodes 21, 22 are bonded to the magnetic wire 1. In this embodiment, furthermore, an electrode substrate formation process S3A is performed before the substrate bonding process S4, in which electrodes 21, 22 and a frame body 62 are formed on the substrate 72, and a magnetic member formation process S1 is performed before the masking process S22, in which a conductor 3, an electrode 43, a magnetization fixed layer 41, a barrier layer 42 and an insulating layer 81 are formed on the substrate 71, and after the magnetic member formation process S1, an initialization process (not shown) is performed in which the magnetization fixed layers 41 of all domain wall motion elements 10A on the substrate 71 are aligned in an upward or downward magnetization direction.

In this embodiment, on the substrate 71, the surface of the frame 61 and the surfaces at the joints between the electrodes 21 and 22 of the magnetic nanowire 1 are formed flat and smooth on the same plane. On the substrate 71, this plane becomes the joint surface B. On the other hand, on the substrate 72, the frame 62 and the electrodes 21 and 22 are formed to protrude, and their surfaces (the upper surface with the substrate 72 facing downward) are formed flat and smooth on the same plane. On the substrate 72, this plane becomes the joint surface B.

(Electrode substrate forming process)
In the electrode substrate forming process S3A, the electrodes 21, 22, and the frame 62 are formed on the substrate 72 with the same thickness in their respective predetermined regions. In the present embodiment, as an example, the electrodes 21 and 22 are formed by depositing Cu by sputtering. Therefore, the electrode substrate forming process S3A can be performed in the same manner as the magnetic fine wire substrate forming process S2 in the first embodiment. That is, a masking process S32A is performed on the substrate 72 using a photoresist for lift-off to form a mask with an area in which the electrodes 21 and 22 and the frame 62 are to be formed, an electrode material depositing process S35A is performed to deposit a metal electrode material for forming the electrodes 21 and 22, and a lift-off process S37 is performed to remove the mask, in that order. In the electrode material depositing process S35A, it is preferable to apply a deposition method that maintains the surface properties (smoothness) of the base, such as sputtering. When a film is formed by sputtering, the productivity decreases as the film becomes thicker, and, although this depends on the metal electrode material, the smoothness tends to decrease, so it is preferable not to make the electrodes 21 and 22 excessively thick.

(Magnetic member forming process)
In the magnetic member forming step S1, a member to be placed below the magnetic nanowire 1 is formed on the substrate 71, and the surface is flattened with an insulating layer 81. That is, in this embodiment, in the magnetic member forming step S1, the conductive wire 3 and the electrode 43 are formed in their respective predetermined regions on the substrate 71 (S11), the magnetization fixed layer 41 and the barrier layer 42 are laminated in order on the electrode 43, and the surface including the barrier layer 42 is flattened with an insulating layer 81 (S12 to S16). The magnetic member forming step S1 will be described in detail below with reference to Figures 11A to 11C. Note that Figures 11A to 11C show end views of a cut portion.

In the magnetic member forming step S1, the conductor 3 and the electrode 43 can be formed, for example, together with the insulating layer 81 around them, as in the electrode substrate forming step S3 of the first embodiment. First, an insulating film (e.g., SiO ₂ , indicated by the reference symbol "81'" in the drawing) that forms the insulating layer 81 is formed on the substrate 71 to a thickness greater than that of the conductor 3 and the electrode 43. Then, the insulating film in the region where the conductor 3 and the electrode 43 are to be formed is removed by photolithography and etching. Then, a metal electrode material (e.g., Au) is formed by electroless plating or by electroplating after forming a seed layer by sputtering, and embedded in the groove of the insulating film. Then, the surface is ground by the CMP method to remove the plating film other than the conductor 3 and the electrode 43 to expose the insulating film, and the surface is further polished to make it smooth (FIG. 11A). An insulating film (e.g., SiN) that forms the insulating layer 81 is further formed thereon to the total thickness of the magnetization pinned layer 41 and the barrier layer 42 (S12). On this insulating film 81', a mask PR1 is formed by photolithography using a photoresist for etching and lift-off, leaving open the region (reading region 1r) where the magnetization pinned layer 41 and the barrier layer 42 are to be formed (S13). Then, the insulating film 81' is removed by etching to expose the electrode 43 (S14, FIG. 11B). By sputtering, a magnetic material for forming the magnetization pinned layer 41 and an insulating film for forming the barrier layer 42 are sequentially formed and embedded in the holes of the insulating film (insulating layer 81) (S15, FIG. 11C). After that, the mask PR1 is removed under conditions corresponding to the resist for forming the mask PR1 (S16). The above conditions vary depending on the material of the magnetization pinned layer 41, but it is preferable to set the temperature to 90° C. or less, similar to the lift-off process S25 of the magnetic nanowire substrate forming process S2.

In step S11, the conductor 3 and the electrode 43 can also be formed by sputtering. More specifically, as in steps S12 to S16, a film of SiN is formed on the substrate 71 to the thickness of the conductor 3 and the electrode 43, a mask is formed thereon to remove the SiN, a film of a metal electrode material (e.g., Cu) is formed, and then the mask is removed. In this case, the substrate 71 is made sufficiently smooth to smooth the surface of the magnetic fine wire 1. In addition, it is preferable that the electrode 43 does not overlap the connection part with the electrode 22 of the magnetic fine wire 1 and the frame body 61 in a plan view, and the conductor 3 does not overlap the frame body 61, so that they are not extended to the end of the magnetic memory 50A. With such a shape, even if a minute step occurs at the boundary with the insulating layer 81 on the side of the conductor 3 and the electrode 43 when they are formed, it does not affect the joining. In addition, in order to connect such a conductor 3 and the electrode 43 to an external current source, for example, a through hole is formed in the substrate 71.

(Magnetic Fine Wire Substrate Forming Process)
The mask step S22, the magnetic nanowire material film forming step S24, and the lift-off step S25, that is, the magnetic nanowire substrate forming step S2, can be performed in the same manner as in the first embodiment.

(Substrate bonding process)
The substrate bonding step S4 can be performed in the same manner as in the first embodiment. In this embodiment, the substrates 71 and 72 are bonded together with their back surfaces facing outward, and both ends of the magnetic fine wire 1 on the substrate 71 are bonded to the electrodes 21 and 22 on the substrate 72, and the frame body 61 on the substrate 71 is bonded to the frame body 62 on the substrate 72. When bonding is performed using a Si film as an adhesive layer, a Si film is formed on the bonding surface of the substrate 71 (on the magnetic fine wire 1 and the frame body 61) in the magnetic fine wire material deposition step S24, as in the first embodiment. When a Si film is formed on the substrate 72, a Si film is formed on the metal electrode material constituting the electrodes 21 and 22 and the frame body 62 in the electrode material deposition step S35A of the electrode substrate formation step S3A.

(Initialization process)
In the initialization step, a magnetic field exceeding the coercive force of the magnetization fixed layer 41 is applied from the outside to align the magnetization direction of the magnetization fixed layer 41 of all the domain wall motion elements 10A to an upward or downward direction. The initialization step may be performed at any stage after the magnetization fixed layer 41 is formed, i.e., after the magnetic member forming step S1. A magnetic field may be applied to the magnetic memory 50A after the substrate joining step S4, or a magnetic field is applied to the substrate 71 on which the magnetization fixed layer 41 is formed, if the initialization step is performed before the substrate joining step S4.

If the electrodes 21, 22 are a pattern or metal material that can be etched (wet or dry etched), the electrodes 21, 22 and the frame 62 can be formed by processing a metal film in the electrode substrate formation process S3A. That is, a film of a metal electrode material is formed on the entire surface of the substrate 72 by plating or sputtering, or a metal foil is attached to form a metal film. After smoothing the surface of this metal film as necessary, it is processed into the shape of the electrodes 21, 22 and the frame 62 by photolithography and etching.

In this embodiment, the magnetic nanowire 1 is joined to the electrodes 21, 22 only at both ends of its upper surface, and the remaining areas are voids. Therefore, even if a minute step occurs at the boundary between the barrier layer 42 and the insulating layer 81 in the read area 1r and the step is carried over to the upper surface of the magnetic nanowire 1 above, it does not affect the junction. Note that this step is kept within a range that does not affect the movement of the domain wall in the magnetic layer 11.

[Operation of magnetic memory]
In the magnetic memory 50A, similarly to the spatial light modulator 50 according to the first embodiment, a current source for applying a magnetic field is connected to the conductor 3, and a current source for moving a magnetic domain is connected between the electrodes 21 and 22 of each of the domain wall motion elements 10A, one of which is connected via a switch, so that connection/disconnection can be switched for each of the domain wall motion elements 10A. The magnetic memory 50A further connects a current source for reading data between the electrodes 43 and 22 for each of the domain wall motion elements 10A.

The writing method of the magnetic memory 50A according to this embodiment is the same as that of the spatial light modulator 50 according to the first embodiment. The reading method of the magnetic memory 50A is to move the memory cell in the magnetic nanowire 1 from which data is to be read to the read region 1r by supplying a current I _m from the magnetic domain movement current source to the magnetic nanowire 1, and then supply a constant current smaller than the current for moving the magnetic domain wall of the magnetic layer 11 from the data read current source connected to the electrodes 43 and 22. The output of the magnetic domain wall motion element 10A is compared with a reference potential by a voltage comparator connected to the data read current source, and data "1" or "0" corresponding to the high or low resistance of the magnetoresistance effect element 4 is determined. Therefore, as in the writing, every time one pulse of the current I _m is supplied, the data read current source supplies a constant current during the stop period to detect the magnetization direction in the read region 1r, and data can be read out one memory cell at a time in the order of the x addresses in the magnetic domain wall motion element 10A. The data reading may be performed by selecting, for example, each of the domain wall motion elements 10A (y addresses one by one), or may be performed in parallel for all the y addresses.

In the magnetic domain wall motion element 10A of the magnetic memory 50A according to this embodiment, when the magnetic domain of the magnetic layer 11 moves due to the supply of the current I _m and reaches the end on the electrode 22 side, the data of the memory cell is lost. In order to continuously store the data of the memory cell moved to the read area 1r for data reading in the magnetic domain wall motion element 10A, an external storage device that temporarily stores the read data is connected to the magnetic memory 50A, and the data of the external storage device is written again to the write area 1w in parallel with the reading of the data of the subsequent x address, that is, the magnetic field application current source supplies the current +I _w /-I _w to the conductor 3 (see Patent Documents 6 and 7). Alternatively, the magnetic nanowire 1 is configured so that the data of the memory cell is not lost by providing a buffer (register) area of the same nanowire length as the memory area 1a on the electrode 22 side of the read area 1r (see Patent Documents 5 and 6).

The domain wall moving device according to this embodiment can also be a spatial light modulator (see FIG. 2) like the first embodiment. In this case, the magnetization fixed layer 41 and barrier layer 42 of the magnetoresistance effect element 4, and the electrode 43 are not necessary, so in the magnetic member forming step S1, only the conductor 3 and the insulating layer 81 that covers it and flattens the upper surface are formed on the substrate 71. Alternatively, as in the first embodiment, the magnetic fine wire 1 and frame 61 can be formed directly on the substrate 71 without performing the magnetic member forming step S1, and the conductor 3 can be formed on the substrate 72 in the electrode substrate forming step S3A, as in the modified example described below.

(Modification)
In the magnetic memory 50A according to the present embodiment, the magnetic fine wires 1 may not be linear, and may not be arranged parallel to each other. Therefore, each of the magnetic fine wires 1 may be formed in an arc shape and arranged in a concentric circle shape (Patent Document 7). In this case, the substrates 71 and 72 may be disk-shaped. Furthermore, the magnetic fine wires 1 may be bent or constricted at the boundary between the cells in the memory area 1a, as in the modified example of the first embodiment. The magnetic fine wires 1 may be bent or curved so that the interval between the ends of the adjacent magnetic fine wires 1 is widened, and the ends may be formed wider. Note that the bending angle and curvature of the magnetic fine wire 1 are designed to be within a range that does not interfere with the domain wall movement in the magnetic layer 11 from the write area 1w to the read area 1r (or to the buffer area). With this configuration, the accuracy of alignment in the substrate bonding process S4 can be kept low relative to the memory density of the magnetic memory 50A. Alternatively, the gap may be widened only on one end side of the magnetic nanowire 1 (eg, the electrode 21 side), and the electrode 22 on the other end side may be formed in a straight line in the y direction crossing all the magnetic nanowires 1 for common use.

The magnetic memory 50A may have electrodes 21, 22, or even frame 62, in a two-layer structure of a plated film and a sputtered film, with the plated film embedded in an insulating layer 82 formed on a substrate 72 and only the sputtered film protruding from the periphery. This type of magnetic memory 50A may also be configured without a substrate 72, similar to the spatial light modulator 50 according to the first embodiment (see the third embodiment shown in FIG. 14).

In addition, the magnetic domain wall motion element 10A may have the conductor 3 disposed above the magnetic nanowire 1, as in the magnetic domain wall motion element 10 of the first embodiment. For this purpose, the conductor 3 is formed on the substrate 72 in the electrode substrate forming step S3A. For example, steps S32A, S35A, and S37 (electrode substrate forming step S3A) are repeated twice to form the electrodes 21, 22 and the frame 62 separately from the conductor 3. Alternatively, the conductor 3 is formed simultaneously with the electrodes 21, 22 and the frame 62 to the same thickness as these, and then a mask is formed to cover the electrodes 21, 22 and the frame 62, and the conductor 3 is thinned by etching. Alternatively, as described above, the electrodes 21, 22 and the frame 62 are formed as a two-layer structure of a plating film and a sputtering film, and the conductor 3 is formed only from a plating film (see the third embodiment shown in FIG. 14).

The magnetic memory 50A according to this embodiment may include a magnetic field application member 3 for each domain wall motion element 10A, as in the modified example of the first embodiment. In addition, the domain wall motion element 10A may be an STT type domain wall motion element in which the magnetic nanowire 1 does not include a channel layer 12.

The domain wall motion device according to this embodiment is not limited to a racetrack memory, and may be a SOT-MRAM or a spatial light modulator that includes a domain wall motion element for each memory cell and pixel (see Patent Document 11). That is, the spatial light modulator (domain wall motion device) 50B according to the modified example of the second embodiment shown in FIG. 12 includes domain wall motion elements 10B arranged two-dimensionally, and a frame 6A surrounds all of the domain wall motion elements 10B. The arrangement direction of the pixels (domain wall motion elements 10B) does not have to be aligned with the fine wire direction (x direction) of the magnetic fine wire 1 of the domain wall motion element 10B. The spatial light modulator 50B according to this modified example is a reflective spatial light modulator that applies a transparent substrate to the substrate 71 and emits light from the substrate 71 side.

12, in the magnetic domain wall motion element 10B, the magnetic nanowire 1 is partitioned in the direction of the nanowire between the connection parts with the electrodes 21 and 22 into a first magnetization fixed region _1p1 , a display region 1a, and a second magnetization fixed region _1p2 in that order, and the display region 1a becomes the opening of the pixel. In the first magnetization fixed region _1p1 and the second magnetization fixed region _1p2 , the magnetization directions of the magnetic layer 11 are fixed upward and downward, respectively. For this reason, the magnetic domain wall motion element 10B includes a nanomagnet 33 on the upper side of the magnetic nanowire 1 as a magnetization fixing means for the magnetic layer 11 (see Patent Document 11).

The nanomagnet 33 is a very small bar magnet aligned along the direction of the magnetic nanowire 1, with its x-direction length longer than its y-direction length and thickness. The nanomagnet 33 is arranged to face the display region 1a of the magnetic nanowire 1, avoiding the regions where the electrodes 21 and 22 are formed and their vicinity, so that both ends face the magnetization fixed regions 1p ₁ and 1p _2. The magnetization directions in the magnetization fixed regions 1p ₁ and 1p ₂ of the magnetic layer 11 are fixed upward and downward by the magnetic field generated below the both ends of the nanomagnet 33. The nanomagnet 33 is preferably arranged with a space of 3 nm or more between the magnetic nanowire 1 and the electrodes 21 and 22 electrically connected thereto, while the nanomagnet 33 is preferably arranged with a space of 3 nm or more between the magnetic nanowire 1 and the magnetic nanowire 1 in order to apply a magnetic field to the magnetic layer 11 that is stronger than the magnetic force. The nanomagnet 33 is formed of a hard magnetic material with in-plane magnetic anisotropy, and may be a multilayer film such as a Co/Pt multilayer film in which transition metals such as Fe, Co, Ni, etc. and precious metals such as Pd or Pt are alternately laminated in a thickness ratio of about 2 to 4:1, and the total thickness can be several tens of nm.

The spatial light modulator 50B according to this modification is similar to the circuit configuration of a select transistor type MRAM having 1T1R type memory cells, and therefore further includes a transistor for each pixel, a word line extending in the column direction of the array and inputting to the gate of the transistor, a bit line (not shown) extending in the row direction, and vias 51 and 52 for connecting these to electrodes 21 and 22. One end (electrode 21) of the magnetic nanowire 1 is connected to the bit line via a transistor, and the other end (electrode 22) is connected to a common potential of all pixels. Therefore, these elements can be formed on a substrate 72 (not shown). The transistor is, for example, a MOSFET (metal oxide semiconductor field effect transistor), and can be formed on the surface layer of a Si substrate applied to the substrate 72. The word line, bit line, and vias 51 and 52 can be made of a general metal electrode material. Therefore, in the spatial light modulator 50B, the word lines, bit lines, and vias 51, 52, as well as an insulating layer 82 that covers these, are formed on a substrate 72 having transistors formed on its surface, and the electrodes 21, 22 are provided protruding from the insulating layer 82.

In the manufacturing method of the spatial light modulator according to this modification, the magnetic member forming step S1 is not performed in the manufacturing method of the magnetic memory according to the second embodiment, and before the electrode substrate forming step S3A, a transistor (MOSFET) is formed on the surface of the substrate 72 (Si substrate), various wirings and an insulating layer 82 covering the wirings are formed thereon, and the surface is flattened to expose the vias 51 and 52. In detail, an insulating film forming the insulating layer 82 is formed on the substrate 72 on which the transistor is formed. Then, the formation of through holes and grooves in the insulating film by photolithography and etching, the filling of the through holes and grooves with metal electrode material, and the formation of the insulating film are repeated in order, and a flattening process is further performed in between as necessary to form the bit lines, the word lines connected to the transistors, the vias 51 connecting the transistors and the electrodes 21, and the vias 52 connecting the bit lines and the electrodes 22. Then, the surface is flattened by the CMP method to expose the vias 51 and 52, and further smoothed. Then, in the electrode substrate forming step S3A, the electrodes 21 and 22 and the frame body 62 are formed by sputtering and lift-off. In this modified example, nanomagnets 33 are then formed on the insulating layer 82 by sputtering and lift-off.

This procedure makes it possible to suppress damage caused by heat not only to the magnetic nanowire 1 but also to the nanomagnet 33. Furthermore, in this modified example, a magnetic field is applied to the nanomagnet 33 in its longitudinal direction (+x direction or -x direction) in the initialization process. Therefore, the initialization process is performed on the substrate 72 on which the nanomagnet 33 is formed after the substrate bonding process S4, or before the substrate bonding process S4 and after the electrode substrate formation process S3A.

In the domain wall motion element 10B, the nanomagnet 33 may be arranged so that the vicinity of its end faces each of the magnetization fixed regions 1p ₁ and 1p ₂ of the magnetic nanowire 1. Therefore, the nanomagnet 33 may be a bar magnet along a direction other than the x direction in the xy plane, for example, the y direction, and the domain wall motion element 10B may include two such nanomagnets 33 and arrange them so that the end on the +y side faces one of the magnetization fixed regions 1p ₁ and 1p ₂ of the magnetic nanowire 1 and the end on the -y side faces the other. Furthermore, in this case, the nanomagnet 33 can be shared by two domain wall motion elements 10B adjacent in the y direction in the spatial light modulator 50B. Alternatively, the nanomagnet 33 may be a bar magnet in the z direction made of a hard magnetic material having perpendicular magnetic anisotropy, and two nanomagnets with polarities opposite to each other may be arranged to face each of the magnetization fixed regions 1p ₁ and 1p ₂ of the magnetic nanowire 1. In addition, in the spatial light modulator 50B according to this modification, the domain wall motion element 10B may include a nanomagnet 33 below the magnetic nanowire 1. That is, the nanomagnet 33 is formed on the substrate 71 and embedded in the insulating layer 81. In this case, the nanomagnet 33 is selected from a material that has heat resistance to the processing temperature (baking temperature) in the photolithography (mask step S22) for forming the magnetic nanowire 1. In addition, the nanomagnet 33 is arranged to avoid the display area 1a in a planar view so as not to interfere with the entry and exit of light. Furthermore, even if a minute step occurs at the boundary between the nanomagnet 33 and the insulating layer 81 and the step is carried over to the upper surface of the magnetic nanowire 1 above it, the nanomagnet 33 is arranged to avoid the connection part of the magnetic nanowire 1 with the electrodes 21 and 22 in a planar view so as not to affect the junction. For this reason, the nanomagnet 33 is a bar magnet along one direction other than the x direction in the xy plane, or a bar magnet in the z direction, as described above.

In the spatial light modulator 50B according to this modification, the domain wall motion element 10B may include a magnetization fixed layer magnetically coupled to the magnetic layer 11 in the magnetization fixed regions 1p ₁ and 1p ₂ as a magnetization fixing means of the magnetic layer 11. That is, a spatial light modulator (domain wall motion type device) 50C according to another modification of the second embodiment shown in FIG. 13 includes domain wall motion elements 10C including magnetization fixed layers 31 and 32 arranged in a two-dimensional array. The domain wall motion element 10C includes a magnetic coupling film 34 and a magnetization fixed layer 31 stacked on the lower surface (magnetic layer 11) of the magnetic nanowire 1 in the first magnetization fixed region 1p ₁ , and a magnetic coupling film 34 and a magnetization fixed layer 32 stacked on the lower surface (magnetic layer 11) of the magnetic nanowire 1 in the second magnetization fixed region 1p ₂ , in that order, instead of the nanomagnet 33 of the domain wall motion element 10B. The other configurations of the spatial light modulator 50C are the same as those of the spatial light modulator 50B.

The magnetization pinned layer 31 and the magnetization pinned layer 32 are magnetically coupled to the magnetic layer 11, and the magnetization direction in the coupled region is the same. The magnetization pinned layers 31 and 32 preferably have a coercive force equal to or greater than that of the magnetic layer 11, and may be made of the same magnetic material as the magnetization pinned layer 41 of the magnetoresistance effect element 4. The magnetization pinned layers 31 and 32 may have a length (width) equal to or greater than the width of the magnetic nanowire 1 in the nanowire width direction (y direction), and may be formed to extend outward from the magnetic nanowire 1. The magnetization pinned layers 31 and 32 are fixed in magnetization directions opposite to each other, and therefore preferably have different coercive forces. Therefore, the magnetization pinned layers 31 and 32 are different from each other in any of the magnetic material, thickness, and aspect ratio of the planar shape. The magnetization pinned layer 31 and the magnetization pinned layer 32 can be formed simultaneously in the manufacture of the spatial light modulator 50C, particularly by making them have different shapes in a plan view. For example, the magnetization pinned layer 31 is formed to have a width similar to that of the magnetic nanowire 1, and the magnetization pinned layer 32 is formed to be long in the y direction, extending outward from the magnetic nanowire 1. The magnetic coupling film 34 is made of a non-magnetic metal such as Ru or Ta, and is formed to a thickness of about 1 to 10 nm. Note that the domain wall motion element 10C may not have the magnetic coupling film 34, and the magnetization pinned layers 31 and 32 may be directly connected to the magnetic layer 11.

In the method for manufacturing the spatial light modulator according to the present modification, the magnetic pinned layers 31, 32 and the magnetic coupling film 34 are formed by steps S12 to S16 (see FIG. 10) of the magnetic member forming step S1 in the method for manufacturing the magnetic memory according to the second embodiment before the magnetic nanowire substrate forming step S2. In detail, an insulating film forming the insulating layer 81 is formed on the substrate 71 to the total thickness of the magnetic pinned layers 31, 32 and the magnetic coupling film 34 (S12), a mask with the magnetization pinned regions 1p ₁ and 1p ₂ left open is formed on the insulating film by photolithography (S13), and the insulating film is removed by etching (S14). The magnetic material forming the magnetic pinned layers 31, 32 and the metal material forming the magnetic coupling film 34 are sequentially formed by sputtering and filled into the holes in the insulating film (S15), and then the mask is removed (S16).

In this modified example, in the initialization process, a magnetic field is applied twice to the magnetization fixed layers 31 and 32, with different directions and strengths. That is, the first time, a magnetic field greater than or equal to the coercive force of both magnetization fixed layers 31 and 32 is applied, and the second time, a magnetic field less than the coercive force of magnetization fixed layer 31 and greater than or equal to the coercive force of magnetization fixed layer 32 is applied, with the direction reversed from the first time (when the magnetization fixed layer 31 has a greater coercive force).

In the spatial light modulator (domain wall motion device) 50B, 50C according to the modified example of the second embodiment, the domain wall motion element is provided with a magnetoresistance effect element 4 in the magnetic nanowire 1 as in the second embodiment, and can be made into a SOT-MRAM. In the magnetic memory according to this modified example, the domain wall motion element includes a read area 1r in the storage area 1a of the magnetic nanowire 1 (display area 1a of the domain wall motion element 10B, 10C) and is provided with a magnetoresistance effect element 4. In the magnetic memory, as an example, the bit line extends in the same column direction as the word line, and further includes a source line and a read word line extending in the row direction, and a diode for each memory cell. The electrode 22 of the domain wall motion element is connected to the source line, and the magnetoresistance effect element 4 is connected to the read word line via the electrode 43 and the diode (not shown).

The diode is, for example, a Si diode, and ions are implanted (doped) into polycrystalline silicon (poly-Si) formed on the substrate 71 to form a p-layer and an n-layer, one of which is connected to a read word line and the other to an electrode 43. Alternatively, a Si substrate can be used as the substrate 71, and a diode can be formed on the surface layer. Note that a transistor may be provided instead of the diode.

In the manufacturing method of the magnetic memory according to this modification, in the manufacturing method of the spatial light modulator, in the magnetic member forming step S1, first, a diode, an electrode 43 connected thereto, a read word line, and an insulating film covering these are formed on the substrate 71, the electrode 43 is exposed to make the surface flat, and then the surface is smoothed. Then, as in the manufacturing method of the magnetic memory according to the second embodiment, the magnetization fixed layer 41 and the barrier layer 42 are formed, and before or after that, the magnetization fixed layers 31, 32 and the magnetic coupling film 34, or the nanomagnet 33 and the insulating layer 81 covering it, are formed. Alternatively, following the electrode substrate forming step S3A, the nanomagnet 33 is formed on the insulating layer 82.

Third Embodiment
In the domain wall motion type device according to the first and second embodiments of the present invention, the side surface of the magnetic nanowire of the domain wall motion element is exposed, but the magnetic nanowire may be surrounded by an insulating film. The configuration of the domain wall motion type device according to the third embodiment of the present invention will be described below with reference to Fig. 14. The same elements as those in the first and second embodiments (see Figs. 1 to 13) are given the same reference numerals and description thereof will be omitted.

14, the spatial light modulator (domain wall motion device) 50D according to the third embodiment of the present invention includes a substrate 71, a domain wall motion element 10D including a magnetic fine wire 1 and electrodes 21, 22 connected to the upper surface at both ends thereof, arranged in parallel on the substrate 71 in the direction of the fine wire width of the magnetic fine wire 1, an insulating layer 81 filling the gap between the magnetic fine wires 1 of the domain wall motion element 10D, an insulating layer 82 on the electrodes 21, 22 of the domain wall motion element 10D, and a frame 6B sandwiched between the substrate 71 and the insulating layer 82 and surrounding the arranged domain wall motion element 10D. The external appearance of the spatial light modulator 50D according to this embodiment is that in the domain wall motion device 50 shown in FIG. 1, an insulating layer 81 is laminated on the substrate 71 to embed the magnetic fine wire 1 and the frame (first layer) 61, which is the lower layer of the frame 6B, and the electrodes 21, 22 protrude downward from the insulating layer 82 and have gaps around them. The spatial light modulator 50D has a gap around the domain wall motion element 10D, and the upper surface of the magnetic nanowire 1 except for the connection portion with the electrodes 21 and 22, part of the side surface of the electrodes 21 and 22, and the inner side surface 6s of the frame body (second layer) 62, which is the upper layer portion of the frame body 6B, are exposed, and this gap is a non-oxidizing atmosphere that is isolated from the outside. The spatial light modulator 50D is a transmissive or reflective spatial light modulator, similar to the spatial light modulator 50 according to the first embodiment. As described later, the spatial light modulator 50D is manufactured by bonding a substrate 71 on which the magnetic nanowire 1 and an insulating layer 81 etc. are formed, and a support substrate 73 (see FIG. 7) on which the electrodes 21 and 22 and an insulating layer 82 etc. are formed, at the bonding surface B shown in FIG. 14.

The domain wall motion element 10D includes a magnetic nanowire 1 and electrodes 21 and 22 connected to the upper surface at both ends of the nanowire, and further includes a conductor (magnetic field application member) 3 spaced apart from the upper side near one end of the magnetic nanowire 1. In the spatial light modulator 50D, there is a gap between the magnetic nanowire 1 and the conductor 3, and therefore the lower surface of the conductor 3 is exposed. The magnetic nanowire 1 is formed into a nanowire shape by stacking a magnetic layer 11 made of a perpendicular magnetic anisotropy material and a channel layer 12 made of a topological insulator, and the electrodes 21 and 22 are connected to the channel layer 12 (see FIG. 3). That is, the domain wall motion element 10D has the same configuration as the domain wall motion element 10 of the spatial light modulator 50 according to the first embodiment. However, in the domain wall motion element 10D, the electrodes 21 and 22 are included in the magnetic nanowire 1 in a plan view, and the entire lower surfaces of the electrodes 21 and 22 are connected to the magnetic nanowire 1. The domain wall motion element 10D is formed in a shape in which the electrodes 21 and 22 are enclosed within the magnetic nanowire 1 in a plan view, specifically at the joining surface B, so that the entire lower surfaces of the electrodes 21 and 22 are reliably connected to the magnetic nanowire 1, including any alignment errors during joining at the joining surface B of the spatial light modulator 50D (substrate joining process S4). The ends of the magnetic nanowire 1 may be formed wide as necessary to ensure a sufficient connection area with the electrodes 21 and 22.

The frame body 6B is sandwiched between the substrate 71 and the insulating layer 82, and together with them, seals the magnetic fine wire 1 and the electrodes 21, 22 inside, and also widens the bonding area in the spatial light modulator 50D. The shape of the frame body 6B is the same as that of the frame body 6. The frame body 6B is formed by bonding a frame body (first layer) 61 formed on the substrate 71 with the same material as the magnetic fine wire 1 at the same time, and a frame body (second layer) 62 formed on the insulating layer 82 with the same material as the electrodes 21, 22 at the same time. That is, the frame body 6B has the same layered structure as the frame body 6A of the second embodiment. However, in the spatial light modulator 50D, the frame body 6B has the first layer 61 embedded in the insulating layer 81, and the inner side surface 6s of the second layer 62 exposed. Therefore, in the spatial light modulator 50D, the frame body 62 is sandwiched between the insulating layers 81 and 82, and together with these, the electrodes 21 and 22 are sealed inside. In addition, the frame body 6B is enclosed in the frame body 61 in a plan view, and the entire lower surface of the frame body 62 is connected to the frame body 61. The frame body 6B is formed in a shape in which the frame body 62 is enclosed in the frame body 61 in a plan view, specifically at the joint surface B, so that the entire lower surface of the frame body 62 is reliably connected to the frame body 61, including the alignment error in the bonding at the joint surface B of the spatial light modulator 50D (substrate bonding process S4).

The insulating layer 81 is provided on the substrate 71, and in this embodiment, it fills the gaps between the magnetic nanowires 1 of the domain wall motion element 10D and between the magnetic nanowires 1 and the frame 61 of the frame 6B, and the upper surface is aligned with the magnetic nanowires 1 (channel layer 12) and the frame 61 to make it approximately flat. As in the second embodiment, the insulating layer 81 can be made of a known inorganic insulating material. For example, when the magnetic layer 11 is made of a material that is easily oxidized, such as an RE-TM alloy, it is preferable to use a non-oxide such as SiN or MgO. In addition, an insulating film with low etching selectivity to the insulating layer 81, which serves as an etching stopper film for the insulating layer 81, may be provided on the surface of the substrate 71 (at the interface with the insulating layer 81).

The insulating layer 82 is provided together with the electrodes 21, 22 on a substrate (second substrate) 73 separate from the substrate 71, and the electrodes 21, 22 are partially embedded on the support substrate 73 side and protrude toward the bonding surface B. Therefore, in this embodiment, the insulating layer 82 has a gap between the magnetic nanowire 1 and the insulating layer 81. As in the first embodiment, the insulating layer 82 can be made of a known inorganic insulating material, and _SiO2 and SiOC are preferred because their surfaces can be easily processed to be smooth by CMP or the like.

[Method of manufacturing spatial light modulator]
15, the method for manufacturing the spatial light modulator (domain wall motion device) according to the third embodiment of the present invention includes the steps of: a masking step S22 for forming a mask on an insulating film on the surface of a substrate (first substrate) 71, the masking step S22 leaving an area for the magnetic nanowire 1 and the frame 61 to be formed thereon; an insulating film etching step S23 for etching the insulating film to the same depth as the thickness of the magnetic nanowire 1; a magnetic nanowire material deposition step S24 for depositing the material of the magnetic layer 11 of the magnetic nanowire 1 and the material of the channel layer 12 on the substrate 71 in sequence; a lift-off step S25 for removing the mask at 90° C. or less; and a substrate bonding step S4 for bonding the substrate (second substrate) 73 on which the electrodes 21 and 22, the conductive wire 3, and the frame 62 are formed, to the substrate 71 at 90° C. or less so that the electrodes 21 and 22 are bonded to the magnetic nanowire 1. In this embodiment, the insulating film deposition step S21 for depositing an insulating film forming an insulating layer 81 on the substrate 71 is performed before the masking step S22. A series of steps S21 to S25 is appropriately referred to as a magnetic fine wire substrate forming step S2A. In addition, before the substrate bonding step S4, an electrode substrate forming step S3B is performed to form the electrodes 21 and 22, the conductive wire 3, the frame 62, and the insulating layer 82 on the support substrate 73, and after the substrate bonding step S4, a substrate removing step S5 is performed to remove the support substrate 73.

In this embodiment, as in the first embodiment, the surfaces of the frame 61 and the magnetic fine wire 1 are formed on the substrate 71 in the same plane, flat, and smooth. In the substrate 71, this plane becomes the joining surface B. Furthermore, an insulating layer 81 is formed on the substrate 71 to fill the spaces between the magnetic fine wires 1 and between the magnetic fine wire 1 and the frame 61, and its surface is made approximately flush with the joining surface B. Meanwhile, on the support substrate 73, the frame 62 and the electrodes 21, 22 are formed to protrude, and their surfaces (the upper surface with the support substrate 73 facing downward) are formed to be flat and smooth on the same plane. In the support substrate 73, this plane becomes the joining surface B. Furthermore, an insulating layer 82 is formed on the support substrate 73 to embed the portions of the electrodes 21, 22 on the support substrate 73 side.

(Electrode substrate forming process)
In the electrode substrate forming process S3B, the electrodes 21, 22, and frame 62 are formed on the support substrate 73 with the same thickness in their respective predetermined regions, and the insulating layer 82 is formed in the other regions with a thickness smaller than that of the electrodes 21, 22, etc., and the surfaces of the electrodes 21, 22, and frame 62 are made smooth. In this embodiment, the conductive wire 3 is further formed with the same thickness as the insulating layer 82. For this purpose, the electrode substrate forming step S3B, for example, sequentially performs the insulating film forming step S31 of forming an insulating film on the support substrate 73, the masking step S32 of forming a mask with an area in which the electrodes 21 and 22 are to be formed, the insulating film etching step S33 of etching the insulating film, the mask removing step S34 of removing the mask, the electrode material forming step S35 of forming a metal electrode material, the smoothing step S36, the masking step S32A of forming a mask with an area in which the electrodes 21 and 22 and the frame 62 are to be formed, the electrode material forming step S35A of forming a metal electrode material, and the lift-off step S37 of removing the mask. That is, the electrode substrate forming step S3B sequentially performs the electrode substrate forming step S3 (see FIG. 4) of the first embodiment and the electrode substrate forming step S3A (see FIG. 10) of the second embodiment.

Steps S31 to S36 are the same as the electrode substrate forming step S3 in the first embodiment. In this embodiment, steps S31 to S35 are performed once, and in the electrode material film forming step S35, a plating film is formed to a thickness greater than the thickness of the conductor 3 (see FIG. 5B). Then, in the next smoothing step S36, the entire surface, that is, the surfaces of the plating films 21', 22', the conductor 3, and the insulating layer 82, are flattened and smoothed. Next, steps S32A, S35A, and S37 are performed in the same manner as the electrode substrate forming step S3A in the second embodiment, and the electrodes 21 and 22 are formed by stacking sputtered films on each of the plating films 21', 22', and the frame 62 is formed on the insulating layer 82.

In this embodiment, the electrodes 21 and 22 have a two-layer structure of a plated film and a sputtered film, and the sputtered film protrudes from the surroundings. The thickness of the protruding layer of the electrodes 21 and 22, i.e., the sputtered film, depends on the thickness of the magnetic nanowire 1, but is preferably 30 nm or more, and more preferably 50 nm or more. With this configuration, the electrodes 21 and 22 can be formed into a thick film that is difficult to form by sputtering alone. The frame 62 may also have a two-layer structure like the electrodes 21 and 22.

(Magnetic Fine Wire Substrate Forming Process)
In the magnetic fine wire substrate forming step S2A, the magnetic fine wire 1 and the frame body 61 of the frame body 61B, as well as the insulating layer 81 that fills the periphery of them flatly, are formed on the substrate 71. Therefore, the magnetic fine wire substrate forming step S2A can be performed in the same manner as steps S12 to S16 (see FIG. 10) of the magnetic member forming step S1 of the second embodiment. That is, first, an insulating film (e.g., SiN, indicated by the reference character "81'" in the figure) that forms the insulating layer 81 is formed on the substrate 71 to a thickness equal to or greater than the thickness of the magnetic fine wire 1 (insulating film forming step S21). Here, in order to make it easier to control the amount of etching (depth) in the subsequent insulating film etching step S23, an etching stopper film (e.g., MgO) is formed on the surface of the substrate 71, and the insulating film 81' is formed to the same thickness as the magnetic fine wire 1. At this time, it is preferable to form the insulating film 81' to a thickness equal to or greater than the maximum thickness in the manufacturing variation of the thickness of the magnetic fine wire 1 so that the entire side surface of the magnetic fine wire 1 is reliably covered with the insulating layer 81. On this insulating film 81', a mask PR2A is formed by photolithography using a photoresist for etching and lift-off, leaving open the areas where the magnetic nanowire 1 and the frame body 61 are to be formed (S22, FIG. 16A). Then, the insulating film 81' is removed by etching to expose the substrate 71 (etching stopper film) (S23, FIG. 16B). Next, a magnetic material for forming the magnetic layer 11 of the magnetic nanowire 1 and a topological insulator for forming the channel layer 12 are sequentially formed by sputtering, and filled into the holes of the insulating film (insulating layer 81) (S24, FIG. 16C). After that, the mask PR2A is dissolved and removed under conditions corresponding to the resist for forming the mask PR2A (S25).

(Substrate bonding process)
The substrate bonding step S4 can be performed in the same manner as in the first and second embodiments. In this embodiment, the electrodes 21 and 22 on the support substrate 73 are bonded to both ends of the magnetic fine wire 1 on the substrate 71, and the frame 62 on the support substrate 73 is bonded to the frame 61 on the substrate 71. When bonding is performed using a Si film as an adhesive layer, a Si film is formed following the metal electrode material constituting the electrodes 21 and 22 and the frame 62 in the electrode material film forming step S35A of the electrode substrate forming step S3B. When a Si film is formed on the substrate 71, the Si film is formed after the lift-off step S25.

(Substrate removal process)
The substrate removing step S5 can be performed in the same manner as in the first embodiment.

In this embodiment, the electrodes 21 and 22 are bonded only to the magnetic fine wire 1 over their entire surfaces, and the frame 62 is bonded only to the frame 61 over its entire surfaces. Although it is difficult to form the surfaces of the magnetic fine wire 1 and the frame 61 with the insulating layer 81 to be completely flush, this configuration allows the insulating layer 81 to be provided to cover the side of the magnetic fine wire 1, since even if a minute step occurs at the boundary between the side of the magnetic fine wire 1 and the insulating layer 81, it does not affect the bonding. Therefore, even if the magnetic layer 11 is made of a material that is easily oxidized, it is not necessary to provide a non-oxidizing atmosphere from the magnetic fine wire material deposition process S24 to before the substrate bonding process S4. Furthermore, in the lift-off process S25, the magnetic layer 11 is not exposed to a solvent or the like.

The domain wall motion device according to this embodiment can also be a magnetic memory (see FIG. 8) like the second embodiment. In this case, before the magnetic fine wire substrate forming process S2A, a magnetic member forming process S1 is performed on a substrate 71 to form an electrode 43, a magnetization fixed layer 41 and a barrier layer 42 of the magnetoresistance effect element 4, and an insulating layer 81 in which these are embedded (see FIG. 10). The conductive wire 3 may also be disposed on the substrate 71 side of the magnetic fine wire 1. Also, as in the modified example of the second embodiment, it can also be an SOT-MRAM or a spatial light modulator that includes a domain wall motion element for each memory cell and each pixel (see FIGS. 12 and 13).

(Modification)
The spatial light modulator 50D according to this embodiment may include a substrate 72, as in the modified example of the first embodiment. Furthermore, as in the second embodiment, the insulating layer 82 may not be provided, and the electrodes 21, 22 and the frame 62 may be formed to protrude entirely from the substrate 72 (see FIG. 8). That is, the electrode substrate forming step S3A is executed instead of the electrode substrate forming step S3B (see FIG. 10), and the substrate removing step S5 is not executed.

Although the above describes various embodiments for implementing the domain wall motion device and the manufacturing method thereof according to the present invention, the present invention is not limited to these embodiments, and various modifications are possible within the scope of the claims.

REFERENCE SIGNS LIST 10, 10A, 10B, 10C, 10D Domain wall motion element 1 Magnetic nanowire 11 Magnetic layer 12 Channel layer 21, 22 Electrode 3 Conductor, magnetic field application member 41 Magnetization fixed layer 42 Barrier layer 43 Electrode 50, 50B, 50C, 50D Spatial light modulator (domain wall motion device)
50A Magnetic memory (domain wall motion device)
6, 6A, 6B Frame body 61 Frame body (first layer)
62 Frame body (second layer)
71 Substrate (first substrate)
72 Substrate (insulating layer, second substrate)
73 Support substrate (second substrate)
81, 82 Insulating layer PR1, PR2, PR2A Mask S1 Magnetic member forming process S2, S2A Magnetic fine wire substrate forming process S21 Insulating film forming process S22 Masking process S23 Insulating film etching process S24 Magnetic fine wire material forming process S25 Lift-off process S3, S3A, S3B Electrode substrate forming process S4 Substrate bonding process S5 Substrate removal process

Claims (13)

A method for manufacturing a domain wall motion device in which domain wall motion elements are arranged, the domain wall motion elements including a magnetic nanowire formed in a nanowire shape having a magnetic layer made of a magnetic material and an electrode connected to a part of the magnetic nanowire in a nanowire direction, the method comprising the steps of:
a masking step of forming a mask on a first substrate, the mask having openings corresponding to a region where the magnetic nanowires are to be formed and a frame-shaped region surrounding all of the magnetic nanowires in a plan view;
a magnetic nanowire material deposition step of depositing a film of a material of the magnetic nanowire on the first substrate;
a lift-off process for removing the mask at 90° C. or less;
A substrate bonding process for bonding a second substrate, on which the electrodes are formed, to the first substrate at a temperature of 90° C. or less so that the electrodes are bonded to the magnetic nanowires. The method for manufacturing a domain wall motion device according to claim 1, wherein the second substrate has an insulator and the electrode embedded in the insulator formed over the entire upper surface. The method for manufacturing a domain wall motion device according to claim 2, wherein a Si film having a thickness of less than 10 nm is formed on the electrode and the insulator of the second substrate. The method for manufacturing a domain wall motion device according to claim 1, wherein the second substrate is made of the same material as the electrodes and has a frame body that overlaps with the frame-shaped region in a plan view. The method for manufacturing a domain wall motion device according to claim 4, wherein a Si film having a thickness of less than 10 nm is formed on the electrode and the frame of the second substrate. the first substrate has an insulating film on a surface thereof;
6. The method for manufacturing a domain wall motion type device according to claim 4, further comprising the steps of: performing an insulating film etching step of etching the insulating film to a depth equal to the thickness of the magnetic nanowire after the masking step and before the magnetic nanowire material deposition step. The method for manufacturing a domain wall motion device according to any one of claims 1 to 5, wherein in the magnetic nanowire material film formation process, a Si film having a thickness of less than 10 nm is formed on the magnetic nanowire material. The magnetic domain wall motion element includes the magnetic nanowire, the magnetic layer being laminated with a channel layer made of a topological insulator, the electrode being connected to the channel layer,
6. The method for manufacturing a domain wall motion type device according to claim 1, wherein the magnetic nanowire material film forming step comprises forming the magnetic material and the topological insulator in this order on the first substrate. The method for manufacturing a domain wall motion device according to any one of claims 1 to 5, characterized in that the steps from the magnetic nanowire material deposition process to the substrate bonding process are carried out in a non-oxidizing atmosphere. A domain wall motion type device including a substrate and arranged thereon, the domain wall motion elements including a magnetic nanowire formed in a nanowire shape with a magnetic layer made of a magnetic material and an electrode connected to a part of the magnetic nanowire in a nanowire direction, the domain wall motion elements including:
Further comprising an insulating layer that fills the gap between the electrodes or is provided on the electrodes, and a frame that is sandwiched between the insulating layer and the substrate and surrounds a region in which the domain wall motion elements are arranged, and is made of the same material as the magnetic nanowire;
A domain wall motion device, characterized in that at least one of the side surface and the top surface other than the connection portion with the electrode of the magnetic nanowire, and at least a part of the inner side surface of the frame are exposed. the frame is formed by laminating a first layer made of the same material as the magnetic nanowire and a second layer made of the same material as the electrodes,
11. The domain wall motion device according to claim 10, wherein an upper surface of the magnetic nanowire other than a portion connected to the electrode and a side surface of the electrode are exposed. an insulating layer is provided between the magnetic nanowires and between the magnetic nanowires and the first layer of the frame;
The domain wall motion device according to claim 11 , wherein, in a plan view, the electrode is contained within the magnetic nanowire, and the second layer of the frame is contained within the first layer. The domain wall motion element is a domain wall motion type device according to any one of claims 10 to 12, in which the magnetic nanowire has a channel layer made of a topological insulator laminated on the magnetic layer, and the electrode is connected to the channel layer.

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