Magnetic fine wire memory and method for manufacturing the same

Abstract

To provide a magnetic fine wire memory that can reduce the possibility of magnetic fine wire breakage and be manufactured with high yield, and a method for manufacturing the same.SOLUTION: A magnetic fine wire memory 100 according to the present invention comprises: a substrate 10; an etching stopper layer 20 formed on the substrate 10; at least one pair of electrodes 40 formed on the etching stopper layer 20; an inter-electrode insulating layer 30 formed with the same thickness adjacent to the at least one pair of electrodes on the etching stopper layer; a magnetic fine wire 51 formed on the at least one pair of electrodes 40 and the inter-electrode insulating layer 30 such that its ends are superposed on the pair of electrodes 40; an interlayer insulating layer 60 formed on the magnetic fine wire 51; and a linear recording element 70 formed on the interlayer insulating layer 60 so as to be orthogonal to the magnetic fine wire 51, wherein the etching stopper layer 20 is composed of a material that is not etched.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic nanowire memory and a manufacturing method thereof, and more particularly to a magnetic nanowire memory that records information by locally reversing magnetization using a current magnetic field, and a manufacturing method thereof. [Background technology]

[0002] Research is underway into magnetic nanowire memory, which records and reproduces binary information corresponding to the direction of magnetization, such as upward or downward, in a medium made of magnetic material processed into a nanowire. Magnetic nanowire memory has a structure in which, for example, a nanowire-shaped conductor (hereinafter referred to as a recording element) is arranged orthogonally above or below a magnetic nanowire via an interlayer insulating layer (Patent Document 1). The magnetic nanowire memory described in Patent Document 1 records information by locally reversing the magnetization in the magnetic nanowire using a current magnetic field generated by applying a current to the recording element. Parallel arrangement and stacking of such magnetic nanowire memories enables ultra-high-speed operation through parallel synchronous control.

[0003] The operation of magnetic nanowire memory consists of "recording," which forms magnetic domains corresponding to recording bits, "driving," which shifts the formed magnetic domains within the magnetic nanowire, and "reading," which detects the magnetization direction of the magnetic domains. Because these three operations are performed by applying electrical signals, magnetic nanowire memory basically does not require any mechanical moving parts and operates as a current-driven device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-027802 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, for ease of manufacturing, magnetic nanowire memories have been manufactured by forming a magnetic nanowire, an interlayer insulating layer, and a recording element on a substrate in that order, and then forming electrodes to drive the magnetic domains of the magnetic nanowire. Here, the reproducing head that detects the magnetization direction of the magnetic domain in the magnetic nanowire needs to be sandwiched between two electrodes (for example, a lower electrode and an upper electrode). Therefore, when attempting to install a reproducing head in a magnetic nanowire memory obtained by the above-mentioned manufacturing method, the reproducing head and the magnetic nanowire are separated by the thickness of the lower electrode for the reproducing head, which may reduce the performance of detecting the magnetization direction (reading performance).

[0006] Therefore, the inventors considered avoiding a decline in read performance by changing the position of the electrodes from the conventional magnetic nanowire memory configuration to the lower side (substrate side), so that the electrodes not only serve to drive the magnetic domains of the magnetic nanowire but also serve as the lower electrodes of the read head. However, the present inventors have confirmed that simply changing the electrode position from the conventional magnetic nanowire memory configuration to the lower side can cause the magnetic nanowire to break (see Comparative Examples 1 and 2, which will be described in detail later).

[0007] From this perspective, an object of the present invention is to provide a magnetic nanowire memory that can be manufactured with a high yield by reducing the possibility of breakage of the magnetic nanowire, and a method for manufacturing the same. [Means for solving the problem]

[0008] The above problems can be solved by the following means. The magnetic nanowire memory of the present invention comprises a substrate, an etching stopper layer formed on the substrate, at least one pair of electrodes formed on the etching stopper layer, an inter-electrode insulating layer formed on the etching stopper layer adjacent to the at least one pair of electrodes and having the same thickness as the at least one pair of electrodes, a magnetic nanowire formed on the at least one pair of electrodes and the inter-electrode insulating layer so that its ends overlap the pair of electrodes, an interlayer insulating layer formed on the magnetic nanowire, and a linear recording element formed on the interlayer insulating layer so as to be perpendicular to the magnetic nanowire, wherein the etching stopper layer is made of a material that is not etched.

[0009] The magnetic nanowire memory according to the present invention includes an etching stopper layer, which allows etching holes for the electrodes to be appropriately formed in the inter-electrode insulating layer and prevents variations in the depth of the etching holes. As a result, the magnetic nanowire memory according to the present invention allows the upper surfaces of the electrodes and the inter-electrode insulating layer to be formed flush with each other, and no step is created at the boundary between the electrodes and the inter-electrode insulating layer, allowing the magnetic nanowire spanning the boundary to be formed on a flat surface.

[0010] In addition, a method for manufacturing a magnetic nanowire memory according to the present invention includes the steps of forming an etching stopper layer on a substrate, forming an interelectrode insulating layer on the etching stopper layer, etching an area in the interelectrode insulating layer for forming at least a pair of electrodes, forming at least a pair of electrodes in the area with the same thickness as the interelectrode insulating layer, forming a magnetic nanowire on the at least a pair of electrodes and the interelectrode insulating layer so that its ends overlap the pair of electrodes, forming an interlayer insulating layer on the magnetic nanowire, and forming a linear recording element on the interlayer insulating layer so as to be perpendicular to the magnetic nanowire, wherein the etching stopper layer is made of a material that cannot be etched.

[0011] The method for manufacturing a magnetic nanowire memory according to the present invention includes a step of forming an etching stopper layer on a substrate, so that etching holes for electrodes can be appropriately formed in the inter-electrode insulating layer, and the occurrence of variations in the depth of the etching holes can be avoided. As a result, the method for manufacturing a magnetic nanowire memory according to the present invention can form the upper surfaces of the electrodes and the inter-electrode insulating layer so as to be flush with each other, and no step occurs at the boundary between the electrodes and the inter-electrode insulating layer, so that the magnetic nanowire spanning the boundary can be formed on a flat surface. [Effects of the Invention]

[0012] The magnetic nanowire memory according to the present invention reduces the possibility of the magnetic nanowire being broken, and can improve yield. The method for manufacturing a magnetic nanowire memory according to the present invention reduces the possibility of the magnetic nanowire being broken, and enables magnetic nanowire memories to be manufactured with a high yield. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing the entire magnetic nanowire memory according to an embodiment of the present invention; [Figure 2] 2 is a schematic diagram of a magnetic body of the magnetic nanowire memory according to the embodiment; FIG. [Figure 3] 1 is a flowchart of a method for manufacturing a magnetic nanowire memory according to the present embodiment. [Figure 4A] 10 is a cross-sectional view showing a state in which an etching stopper layer is formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4B] 10 is a cross-sectional view showing a state in which an inter-electrode insulating layer has been formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4C] 10 is a cross-sectional view showing a state in which a photoresist is formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4D] 10 is a cross-sectional view showing a state in which etching holes have been formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4E]10 is a cross-sectional view showing a state in which an electrode has been formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4F] 10 is a cross-sectional view showing a state in which the photoresist is peeled off and an electrode is formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4G] 10 is a cross-sectional view showing a state in which a photoresist is formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4H] 1 is a cross-sectional view showing a state in which a magnetic material film has been formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. [Figure 4I] 10 is a cross-sectional view showing a state in which the photoresist is peeled off to form a magnetic body in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4J] 10 is a cross-sectional view showing a state in which an interlayer insulating layer and a recording element have been formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 5] FIG. 10 is a schematic diagram showing the entirety of a modified example of the magnetic nanowire memory according to the embodiment. [Figure 6A] 10 is a cross-sectional view showing a state in which an electrode is formed in Comparative Example 1. FIG. [Figure 6B] 10 is a cross-sectional view showing a state in which a magnetic body is formed in Comparative Example 1. FIG. [Figure 6C] 10 is a cross-sectional view showing a state in which an interlayer insulating layer is formed in Comparative Example 1. FIG. [Figure 6D] 10 is a cross-sectional view showing a state in which a recording element is formed in Comparative Example 1. FIG. [Figure 7A] 10 is a cross-sectional view showing a state in which an interelectrode insulating layer is formed in Comparative Example 2. FIG. [Figure 7B] 10 is a cross-sectional view showing a state in which a photoresist is formed in Comparative Example 2. FIG. [Figure 7C] 10 is a cross-sectional view showing a state in which etching holes are formed in Comparative Example 2. FIG. [Figure 7D] 10 is a cross-sectional view showing a state in which an electrode film is formed in Comparative Example 2. FIG. [Figure 7E]It is a cross-sectional view showing the state where the photoresist is peeled off and the electrode is formed in Comparative Example 2. [Figure 7F] It is a cross-sectional view showing the state where the magnetic body, the interlayer insulating layer, and the recording element are formed in Comparative Example 2. [Embodiments for Carrying Out the Invention]

[0014] First, the magnetic fine wire memory according to the present embodiment will be described with reference to FIGS. 1 and 2. Note that the sizes, positional relationships, etc. of the members shown in each drawing may be exaggerated for clarity of explanation.

[0015] [Magnetic Fine Wire Memory According to the Present Embodiment] As shown in FIG. 1, the magnetic fine wire memory 100 according to the present embodiment includes a substrate 10, an etching stopper layer 20, an inter-electrode insulating layer 30, an electrode 40, a magnetic body 50, an interlayer insulating layer 60, and a recording element 70. Further, the magnetic fine wire memory 100 according to the present embodiment may include a reproducing head 80. Hereinafter, each component of the magnetic fine wire memory 100 according to the present embodiment will be described in detail.

[0016] (Substrate) The substrate 10 is a plate-like component that serves as a base for forming each member such as the magnetic body 50 and the recording element 70. The substrate 10 is not particularly limited as long as it is composed of a known substrate material. For example, a Si substrate, a GGG (gadolinium gallium garnet) substrate, a SiC (silicon carbide) substrate, a MgO (magnesium oxide) substrate, an AlN (aluminum nitride) substrate, a Ge (germanium) single crystal substrate, etc. may be mentioned. However, the substrate 10 preferably has a configuration in which a thermal oxide film 11 as shown in FIG. 4A is formed, and a Si substrate with a SiO X film (0 < X ≦ 2) formed thereon is suitable. The thickness of the substrate 10 is not particularly limited, but for example, it is 280 to 775 μm according to JEITA or SEMI standards. In this specification, although the side on which each member is formed with respect to the substrate 10 is described as the upper side, the orientation is not particularly limited during use or manufacturing, and the side (upper side) on which each member is formed may face downward.

[0017] (Etching stopper layer) The etching stopper layer 20 is a layer formed on the substrate 10 and is a layer that blocks etching. Therefore, according to the etching stopper layer 20, when providing an etching hole in the inter-electrode insulating layer 30 formed on the layer 20, the depth of the etching hole can be made uniform (aligned) to the depth up to the upper surface of the etching stopper layer 20. The etching stopper layer 20 is not particularly limited as long as it is made of a material that is not etched (in other words, a material that cannot be shaved by etching), but is preferably an insulating material such as MgO. Although the thickness of the etching stopper layer 20 is not particularly limited, in order to surely play the role of blocking etching, 3 to 5 nm is preferable.

[0018] (Inter-electrode insulating layer) The inter-electrode insulating layer 30 is a layer formed on the etching stopper layer 20 and is a layer formed with the same thickness adjacent to the electrode 40. The inter-electrode insulating layer 30 may be made of a material that is etched (in other words, a material that can be shaved by etching), but SiO2 or SiN X (0 < X ≤ 4 / 3) is preferable. Although the thickness of the inter-electrode insulating layer 30 may be the same as that of the electrode 40, for example, it is 150 to 300 nm.

[0019] When forming etching holes by reactive ion etching using reactive gases such as CF4 or SF6, it is preferable to use a combination in which the interelectrode insulating layer 30 is made of a material that can be removed, while the etching stopper layer 20 is made of a material that cannot be removed, in other words, a combination that allows appropriate anisotropic etching. From this point of view, as described above, the etching stopper layer 20 is made of MgO, and the interelectrode insulating layer 30 is made of SiO2 or SiN X This combination is particularly preferred.

[0020] (electrode) The electrode 40 is a conductor formed on the etching stopper layer 20 and is a layer formed adjacent to the interelectrode insulating layer 30 with the same thickness. A pair (two) of electrodes 40 are provided for one magnetic body 50. In detail, as shown in Fig. 1, the electrode 40a arranged on the left side is arranged so as to overlap with the left end of the magnetic body 50 in the longitudinal direction when viewed from above, and the electrode 40b arranged on the right side is arranged so as to overlap with the right end of the magnetic body 50 in the longitudinal direction when viewed from above. The electrodes 40a and 40b serve as pads for connecting a current control section (not shown) that applies a drive current to the magnetic body 50. The right electrode 80b also serves as a lower electrode for the read head. The electrode 40 is not particularly limited as long as it is a known metal material for electrodes, but examples thereof include metals such as Cu, Al, Au, Ag, Ta, Cr, and Ti, alloys thereof, and multilayer films. Among these, Au and its alloys, which are particularly highly conductive and chemically stable, are preferred. The thickness of the electrode 40 is as described for the interelectrode insulating layer 30. Although the shape of the electrode 40 is rectangular when viewed from above in the drawings, the shape is not particularly limited as long as it can function as an electrode.

[0021] (Relationship between interelectrode insulating layer and electrodes) Forming the interelectrode insulating layer 30 of the same thickness adjacent to the electrode 40 makes it possible to avoid the occurrence of a step corresponding to the thickness of the electrode 40. Furthermore, by making the upper surfaces of the interelectrode insulating layer 30 and the electrode 40 flush with each other, each member such as the magnetic body 50 to be stacked thereon can be formed on a flat surface without any steps. Here, "coplanar" refers to a state in which the upper surfaces of the interelectrode insulating layer 30 and the electrode 40 are approximately on the same plane, specifically, a state in which the difference in height between the upper surfaces of the two in the thickness direction is 10 nm or less (particularly 5 nm or less).

[0022] (magnetic material) The magnetic body 50 is a magnetic member formed on the inter-electrode insulating layer 30 and the electrode 40, and has a linear shape (specifically, a thin wire shape). As shown in Fig. 1, in top view, the left end of the magnetic body 50 overlaps with the left electrode 40a, and the right end of the magnetic body 50 overlaps with the right electrode 40b. This magnetic material 50 is an information recording medium, and records binary information corresponding to the upward or downward magnetization direction (white arrow in FIG. 1) parallel to the thickness direction.

[0023] 2, the magnetic body 50 includes a magnetic nanowire 51 and a topological insulator film 52. However, in the present invention, the topological insulator film 52 is not an essential component, and the magnetic body 50 may be composed of only the magnetic nanowire 51. The magnetic fine wire 51 is not particularly limited as long as it is made of a known magnetic material. For example, it may be made of a multilayer film such as a Co / Pt multilayer film in which a transition metal such as Fe, Co, or Ni and a noble metal such as Pd or Pt are repeatedly laminated, an alloy (RE-TM alloy) or multilayer film of a rare earth metal and a transition metal such as Tb-Fe-Co or Gd-Fe, or a L 10 Examples of the magnetic nanowire 51 include FePt, FePd, etc., which are ordered alloys of the FePt system. The thickness of the magnetic nanowire 51 is, for example, 3 to 10 nm. The topological insulator film 52 is a film made of a "topological insulator" that allows current to flow on the surface of the material but not inside the material, and examples of the insulator include BiSb (bismuth-antimony alloy), Bi2Se3 (bismuth-selenium alloy), Bi2Te3 (bismuth-tellurium alloy), Sb2Te3 (antimony-tellurium alloy), (Bi2Sb3)2Te3 (bismuth-antimony-tellurium alloy), etc. The thickness of the topological insulator film 62 is, for example, 5 to 15 nm. Furthermore, by providing the topological insulator film 52, the current density required to drive the magnetic domains can be significantly reduced, thereby realizing power saving.

[0024] In FIG. 1, the magnetic nanowire memory 100 includes two magnetic bodies 50, but the number of magnetic bodies 50 is not particularly limited. 2, the magnetic body 50 includes a magnetic nanowire 51 and a topological insulator film 52. However, as described above, the magnetic body 50 does not necessarily include the topological insulator film 52, and may further include other films. For example, a barrier layer made of MgO (see JP 2024-13615 A) may be provided between the magnetic nanowire 51 and the topological insulator film 52.

[0025] (Interlayer insulating layer) The interlayer insulating layer 60 is a layer formed on the magnetic body 50 (magnetic nanowire 51) and is an insulating layer between the lower magnetic body 50 and the upper recording element 70 to insulate them from each other. The interlayer insulating layer 60 is not particularly limited as long as it is made of a known insulating material, but examples thereof include oxide films such as SiO2 and Al2O3, Si3N4, and MgF2. The thickness of the interlayer insulating layer 60 is not particularly limited, but is, for example, 25 to 40 nm.

[0026] (recording element) The recording element 70 is a conductor formed on the interlayer insulating layer 60 and has a linear shape (specifically, a thin wire shape). The recording element 70 is arranged so as to be perpendicular to the longitudinal end (the left end in FIG. 1 ) of the magnetic body 50 when viewed from above. A recording current that magnetizes the magnetic body 50 is applied to this recording element 70. The recording element 70 is not particularly limited as long as it is made of a known metal material for electrodes, but examples thereof include metals such as Cu, Al, Au, Ag, Ta, and Cr, and alloys thereof. Among these, Au and its alloys are preferred because they are highly conductive and chemically stable. The thickness of the recording element 70 is not particularly limited, but is, for example, 150 to 300 nm.

[0027] (playhead) The reproducing head 80 is an element that converts a magnetic signal into an electric signal. The reproducing head 80 is disposed above the longitudinal end (the right end in FIG. 1) of the magnetic body 50. One reproducing head 70 is provided for each magnetic body 60. The reproducing head 70 is a magnetic head generally used for magnetic recording, and may be, for example, a tunnel magnetoresistance (TMR) element having a magnetization fixed layer, an intermediate layer, and a magnetization free layer.

[0028] (Other configurations) The magnetic nanowire memory 100 according to this embodiment may also include a current control unit that controls the drive current flowing through the magnetic material 50 via the electrode 40 and the recording current flowing through the recording element 70, a reproduction processing unit that processes signals from the reproduction head 80, and the like.

[0029] [Operation of magnetic nanowire memory] Next, the operation of the magnetic nanowire memory according to this embodiment will be described. The magnetic nanowire memory 100 according to this embodiment performs three operations: recording, driving, and reproduction.

[0030] (record) Recording is an operation of forming magnetic domains (information units) magnetized upward or downward in the magnetic body 50. The magnetic domains are formed by the magnetic field of the recording current applied to the recording element . (Drive) Driving is an operation of moving the magnetic domain in the longitudinal direction of the magnetic body 50 (shifting it in a direction away from the recording element 70). Driving is performed by applying a driving current to the magnetic body 50. During driving, the magnetic domain moves while maintaining its magnetization direction. By repeating the recording and driving operations, the magnetic domains formed in the magnetic body 50 are aligned in the longitudinal direction, and binary information is stored in the magnetic body 50 as shown in FIG. (reproduction) Reproduction is an operation of detecting the magnetization direction of the magnetic domain in the magnetic body 50. The detection of the magnetization direction is performed by the reproduction head 80. The reproduction head 80 detects the magnetization direction of the magnetic domain in the magnetic body 50 located below the member.

[0031] As explained above, the magnetic nanowire memory 100 according to this embodiment includes the etching stopper layer 20, and therefore, there is no variation in the depth of the etching holes H. As a result, the upper surfaces of the interelectrode insulating layer 30 and the electrode 40 are flush with each other, and the magnetic body 50 (magnetic nanowire 51) spanning the boundary between the two members is formed on a flat surface. This prevents the magnetic body 50 (magnetic nanowire 51) from being subjected to unnecessary strain not only during manufacturing but also during operation, and reduces the possibility of breakage.

[0032] [Method of manufacturing magnetic nanowire memory according to this embodiment] Next, a method for manufacturing the magnetic nanowire memory according to this embodiment will be described with reference to FIGS. As shown in Figure 3, the manufacturing method of the magnetic nanowire memory according to this embodiment includes an etching stopper layer forming step S1, an interelectrode insulating layer forming step S2, an electrode forming step S3 (S31 to S34), a magnetic material forming step S4, an interlayer insulating layer forming step S5, and a recording element forming step S6. Each step of the method for manufacturing a magnetic nanowire memory according to this embodiment will be described in detail below.

[0033] (Etching stopper layer formation process: step S1) In the etching stopper layer formation step S1, as shown in FIG. 4A, an etching stopper layer 20 is formed by film deposition on a substrate 10 (more specifically, a thermal oxide film 11 formed on the upper surface of the substrate 10). The film deposition method is not particularly limited as long as it is a conventionally known method, and examples thereof include vapor deposition (electron beam vapor deposition) and sputtering. The same applies to the film deposition methods for each layer described below.

[0034] (Inter-electrode insulating layer forming process: step S2) In the interelectrode insulating layer forming step S2, the interelectrode insulating layer 30 is formed on the etching stopper layer 20 by film deposition, as shown in FIG. 4B.

[0035] (Electrode formation process: step S3) In the electrode formation step S3 (S31 to S34), an electrode 40 having the same thickness as the interelectrode insulating layer 30 is formed in the same layer as the layer 30. 4C, photoresist R is first formed on inter-electrode insulating layer 30 in a pattern in which gaps V are formed where electrodes 40 are to be provided (S31). The patterning of photoresist R may be performed by known photolithography, in which photoresist R is uniformly formed on inter-electrode insulating layer 30 and then the photoresist R is removed from the areas where gaps V are to be formed, or may be performed by electron beam lithography. Next, as shown in FIG. 4D, etching holes H are formed in the interelectrode insulating layer 30 where the photoresist R is not formed when viewed from above (S32). In this step, etching is stopped by the etching stopper layer 20, so the depth of the etching holes H can be made uniform down to the top surface of the etching stopper layer 20. Note that any known etching method may be used, but it is also possible to use a method in which the etching stopper layer 20 is made of MgO and the interelectrode insulating layer 30 is made of SiO2 or SiN X In this case, reactive ion etching using reactive gases such as CF4 and SF6 is preferred. Next, as shown in Fig. 4E, the electrode 40 is formed (S33). Finally, as shown in Fig. 4F, the photoresist R is removed to form the electrode 40 (S34). Through these steps, the electrode 40 can be formed in the same layer as the interelectrode insulating layer 30 and has the same thickness as the layer 30. As a result, the upper surface of the interelectrode insulating layer 30 and the upper surface of the electrode 40 become flush with each other, and there is no step at the boundary between the two members (the area surrounded by the dotted circle in FIG. 4F).

[0036] (Magnetic body forming process: step S4) In the magnetic body forming step S4, the magnetic body 50 is formed on the inter-electrode insulating layer 30 and the electrode 40. Specifically, as shown in FIG. 4G, a photoresist R is formed in a predetermined pattern. Next, as shown in FIG. 4H, a magnetic body 50 is deposited. If the magnetic body 50 has a structure including both a magnetic nanowire 51 and a topological insulator film 52, the two films may be deposited in the state shown in FIG. 4H. Finally, as shown in FIG. 4I, the photoresist R is peeled off to form the magnetic body 50. The patterning and peeling of the photoresist R in the magnetic material forming step S4 is the same as in the electrode forming step S3.

[0037] (Interlayer insulating layer forming process: step S5) In the interlayer insulating layer forming step S5, the interlayer insulating layer 60 is formed on the magnetic body 50. The interlayer insulating layer 60 can be formed in the same manner as the magnetic body 50, by forming a photoresist with a predetermined pattern, depositing a material film, and peeling off the photoresist.

[0038] (Recording element formation process: step S6) In the recording element forming step S6, the recording element 70 is formed on the interlayer insulating layer 60. The recording element 70 can be formed in the same manner as the magnetic body 50, by forming a photoresist with a predetermined pattern, depositing a material film, and peeling off the photoresist.

[0039] (Other processes) The method for manufacturing the magnetic nanowire memory according to this embodiment may include a step of forming the read head 80, etc., after the recording element forming step S6.

[0040] As explained above, the method for manufacturing the magnetic nanowire memory according to this embodiment includes the step of forming the etching stopper layer 20, and therefore, there is no variation in the depth of the etching holes H formed in the interelectrode insulating layer 30. As a result, the upper surfaces of the interelectrode insulating layer 30 and the electrode 40 can be formed to be flush with each other, and the magnetic body 50 (magnetic nanowire 51) spanning the boundary between the two members can be formed on a flat surface. This reduces the possibility of the magnetic body 50 (magnetic nanowire 51) breaking during manufacturing, and improves yield.

[0041] [Variations] Next, a modified example of the magnetic nanowire memory according to this embodiment will be described with reference to FIG. As shown in FIG. 5, a magnetic nanowire memory 101 according to the modification includes an upper electrode 90 for the read head on top of a read head 80. The upper electrode 90 is a reproducing head. Furthermore, the magnetic nanowire memory 101 is configured such that the interlayer insulating layer 60 does not extend to the right end of the magnetic body 50, and the interlayer insulating layer 60 does not exist between the reproducing head 80 and the magnetic body 50. With this configuration, no other members (the lower electrode for the reproducing head, the interlayer insulating layer 60) are interposed between the reproducing head 80 and the magnetic body 50, so the reproducing head 80 and the magnetic body 50 can be brought close to or in close contact with each other, preventing a decrease in read performance. Furthermore, the magnetic nanowire memory 101, like the magnetic nanowire memory 100, is provided with the etching stopper layer 20, and therefore the upper surface of the interelectrode insulating layer 30 and the upper surface of the electrode 40 can be made "flush". The upper electrode 90 for the reproducing head may be formed in the same manner as the electrode 40. In detail, the process of forming the upper electrode 90 may be carried out by the steps of forming a photoresist, forming an electrode film, and peeling off the photoresist to form the electrode.

[0042] Finally, in order to clarify the effectiveness of the magnetic nanowire memory and the manufacturing method thereof according to this embodiment, a conventional manufacturing method of a magnetic nanowire memory will be described.

[0043] [Comparative Example 1: Manufacturing method of magnetic nanowire memory without inter-electrode insulating layer] 6A to 6D, a description will be given of "Comparative Example 1: Manufacturing method of magnetic nanowire memory without inter-electrode insulating layer," which has a configuration in which the electrode position is changed to the lower side from the configuration of the conventional magnetic nanowire memory but no inter-electrode insulating layer is provided. First, an electrode 40 is formed on a substrate 10 (more specifically, a thermal oxide film 11) (FIG. 6A). Then, a magnetic body 50 is formed on the electrode 40 (FIG. 6B). Then, an interlayer insulating layer 60 is formed on the magnetic body 50 (FIG. 6C). Then, a recording element 70 is formed on the interlayer insulating layer 60 (FIG. 6D). The electrode 40, magnetic body 50, interlayer insulating layer 60, and recording element 70 are formed by forming a photoresist with a predetermined pattern, depositing each material, and peeling off the photoresist. According to "Comparative Example 1: Manufacturing method of magnetic nanowire memory without inter-electrode insulating layer," a steep step corresponding to the height (for example, several hundred nm) of electrode 40 occurs in the area surrounded by the dotted circle in Fig. 6D. As a result, magnetic body 50 spanning this steep step is highly likely to break.

[0044] Comparative Example 2: Manufacturing method of magnetic nanowire memory without providing an etching stopper layer "Comparative Example 2: Manufacturing method of magnetic nanowire memory without etching stopper layer", which has a configuration in which an interelectrode insulating layer is provided but no etching stopper layer is provided, will be described with reference to FIGS. 7A to 7F. First, an interelectrode insulating layer 30 is formed on a substrate 10 (more specifically, a thermal oxide film 11) (FIG. 7A). Then, a photoresist R is formed in a predetermined pattern (FIG. 7B). Then, etching holes H are formed (FIG. 7C). Then, electrodes 40 are deposited (FIG. 7D). Then, the photoresist R is stripped to form the electrodes 40 (FIG. 7E). Then, an interlayer insulating layer 60 and a recording element 70 are formed (FIG. 7F). The interlayer insulating layer 60 and the recording element 70 are formed by forming a photoresist in a predetermined pattern, depositing each material, and stripping the photoresist. According to "Comparative Example 2: Manufacturing Method of Magnetic Nanowire Memory Without Etching Stopper Layer," the interelectrode insulating layer 30 is provided, thereby preventing the occurrence of a step corresponding to the height of the electrode 40 (e.g., several hundred nm). However, in FIG. 7C, even if etching is performed to the thickness of the interelectrode insulating layer 30, the etching process is time-controlled, resulting in variations in the depth of the etching hole H (the dotted circle in FIG. 7C) within a range of about ±10% even within the same substrate and the same lot. Therefore, even if an electrode 40 having the same thickness as the interelectrode insulating layer 30 is formed, a step corresponding to the variation in the depth of the etching hole (e.g., several tens of nm) will occur in the area surrounded by the dotted circle in FIG. 7E. As a result, the magnetic body 50 (magnetic nanowire 51) spanning this step is more likely to break.

[0045] (Study based on comparison with Comparative Examples 1 and 2) According to the magnetic nanowire memory and its manufacturing method of this embodiment, an interelectrode insulating layer 30 of the same thickness is formed adjacent to the electrode, and therefore, unlike "Comparative Example 1: Manufacturing method of magnetic nanowire memory without providing an interelectrode insulating layer", it is possible to avoid a situation where a steep step corresponding to the height of the electrode 40 (e.g., several hundred nm) occurs. Furthermore, according to the magnetic nanowire memory and its manufacturing method of this embodiment, an etching stopper layer 20 is formed on the substrate 10 (more specifically, the thermal oxide film 11 formed on the substrate 10), and therefore, unlike "Comparative Example 2: Manufacturing method of a magnetic nanowire memory without providing an etching stopper layer", it is possible to avoid a situation in which a step occurs due to variations in the depth of the etching hole (for example, several tens of nm). As a result, the magnetic nanowire memory and its manufacturing method according to this embodiment can significantly reduce the possibility of breakage of the magnetic material (magnetic nanowire) and improve yield compared to "Comparative Example 1: Manufacturing method of magnetic nanowire memory without providing an inter-electrode insulating layer" and "Comparative Example 2: Manufacturing method of magnetic nanowire memory without providing an etching stopper layer." [Explanation of symbols]

[0046] 10 Substrate 20 Etching stop layer 30 Inter-electrode insulating layer 40 electrodes 40a electrode (left electrode) 40b electrode (right electrode) 50 Magnetic materials (magnetic nanowires only, or magnetic nanowires + topological insulator films) 51 Magnetic thin wire 52 Topological insulator membranes 60 Interlayer insulation layer 70 Recording element 80 Playhead 100 Magnetic nanowire memory R Photoresist V Gap (where the recording element is located) H Etching hole 90 Upper electrode for read head 101 Magnetic nanowire memory (variation)

Claims

1. A substrate; an etching stopper layer formed on the substrate; At least one pair of electrodes formed on the etching stopper layer; an inter-electrode insulating layer formed on the etching stopper layer and adjacent to the at least one pair of electrodes to the same thickness; a magnetic nanowire formed on the at least one pair of electrodes and the inter-electrode insulating layer so that ends of the magnetic nanowire overlap the pair of electrodes; an interlayer insulating layer formed on the magnetic nanowire; a linear recording element formed on the interlayer insulating layer so as to be perpendicular to the magnetic nanowire; The etching stopper layer is made of a material that is not etched.

2. 2. The magnetic nanowire memory according to claim 1, wherein the upper surfaces of the electrodes and the upper surface of the interelectrode insulating layer are flush with each other.

3. 3. The magnetic nanowire memory according to claim 1, wherein the etching stopper layer is made of MgO.

4. The interelectrode insulating layer is made of SiO ２ or SiN Ｘ 3. The magnetic nanowire memory according to claim 1, wherein:

5. forming an etching stopper layer on the substrate; forming an inter-electrode insulating layer on the etching stopper layer; forming regions for forming at least a pair of electrodes in the inter-electrode insulating layer by etching; forming at least one pair of electrodes in the region with the same thickness as the inter-electrode insulating layer; forming a magnetic nanowire on the at least one pair of electrodes and the inter-electrode insulating layer so that ends of the magnetic nanowire overlap the pair of electrodes; forming an interlayer insulating layer on the magnetic nanowire; forming a linear recording element on the interlayer insulating layer so as to be perpendicular to the magnetic nanowire; The method for manufacturing a magnetic nanowire memory, wherein the etching stopper layer is made of a material that is not etched.

6. 6. The method for manufacturing a magnetic nanowire memory according to claim 5, wherein the upper surfaces of the electrodes and the upper surfaces of the interelectrode insulating layers are flush with each other.

7. 7. The method for manufacturing a magnetic nanowire memory according to claim 5, wherein the etching stopper layer is made of MgO.

8. The interelectrode insulating layer is made of SiO ２ or SiN Ｘ 7. The method for manufacturing a magnetic nanowire memory according to claim 5, wherein:

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