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 improve 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; a linear recording element 40 formed on the etching stopper layer 20; an inter-element insulating layer 30 formed with the same thickness adjacent to the recording element 40 on the etching stopper layer 20; an interlayer insulating layer 50 formed on the recording element 40 and the inter-element insulating layer 30; a magnetic fine wire 61 formed so as to be orthogonal to the recording element 40 on the interlayer insulating layer 50; and a topological insulating film 62 formed on the magnetic fine wire, and 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 mechanically moving parts and operates as a current-driven device. Therefore, power saving is essential if we aim to put magnetic nanowire memory into practical use. Therefore, in Patent Document 2 and other documents, the present applicant has proposed a technique of bonding a topological insulator film to the surface of a magnetic nanowire, with the aim of reducing the power consumption of magnetic nanowire memories. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-027802 [Patent Document 2] Japanese Patent Publication No. 2023-151811 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, magnetic nanowire memories have been manufactured by forming the magnetic nanowire, an interlayer insulating layer, and a recording element on a substrate in that order, due to the ease of the manufacturing process. However, in this conventional manufacturing method, high-temperature processing (such as resist baking) is required to properly form the magnetic nanowire and recording element without generating burrs. However, when manufacturing a magnetic nanowire memory with a topological insulator film using conventional manufacturing methods, the materials that make up the insulator film (such as Bi and Sb atoms) can thermally diffuse into the magnetic nanowire during high-temperature processing, potentially significantly degrading its magnetic properties.

[0006] Therefore, the inventors conceived the idea of ​​avoiding the adverse effects of high-temperature treatment by inverting the structure of conventional magnetic nanowire memory and configuring it so that the formation of the magnetic nanowire and topological insulator film is carried out at the end of the manufacturing process. However, the present inventors have confirmed that simply inverting the configuration of a conventional magnetic nanowire memory can result in cases where the magnetic nanowire is broken (see Comparative Examples 1 and 2, which will be described in detail later).

[0007] From this viewpoint, an object of the present invention is to provide a magnetic nanowire memory and a manufacturing method thereof that can reduce the possibility of breakage of the magnetic nanowire and improve yield. [Means for solving the problem]

[0008] The above problems can be solved by the following means. The magnetic nanowire memory according to the present invention comprises a substrate, an etching stopper layer formed on the substrate, a linear recording element formed on the etching stopper layer, an inter-element insulating layer formed on the etching stopper layer adjacent to the recording element and having the same thickness, an interlayer insulating layer formed on the recording element and the inter-element insulating layer, a magnetic nanowire formed on the interlayer insulating layer so as to be perpendicular to the recording element, and a topological insulator film formed on 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 write element to be properly formed in the inter-element insulating layer, thereby preventing 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 write element and the inter-element insulating layer to be formed flush with each other, and no step is created at the boundary between the write element and the inter-element insulating layer, allowing the magnetic nanowire spanning the boundary to be formed on a flat surface.

[0010] Furthermore, 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 inter-element insulating layer on the etching stopper layer, etching a region in the inter-element insulating layer for forming a linear recording element, forming the recording element in the region to the same thickness as the inter-element insulating layer, forming an interlayer insulating layer on the recording element and the inter-element insulating layer, and forming a magnetic nanowire on the interlayer insulating layer so as to be perpendicular to the recording element and forming a topological insulator film on the magnetic nanowire, wherein the etching stopper layer is made of a material that is not 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 write elements can be appropriately formed in the inter-element 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 write element and the inter-element insulating layer so as to be flush with each other, and no step occurs at the boundary between the write element and the inter-element 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-element 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]FIG. 10 is a cross-sectional view showing a state in which a recording element has been formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. [Figure 4F] 10 is a cross-sectional view showing a state in which the photoresist is peeled off to form a recording element 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] 10 is a cross-sectional view showing a state in which an interlayer insulating layer has been formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4I] 10 is a cross-sectional view showing a state in which the photoresist is peeled off and an interlayer insulating layer is formed 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 a photoresist is formed in the method for manufacturing a magnetic nanowire memory according to the embodiment. FIG. [Figure 4K] 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 4L] 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 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 a recording element is formed in Comparative Example 1. FIG. [Figure 6B] 10 is a cross-sectional view showing a state in which an interlayer insulating layer is formed in Comparative Example 1. FIG. [Figure 6C] 10 is a cross-sectional view showing a state in which a magnetic body is formed in Comparative Example 1. FIG. [Figure 7A] 10 is a cross-sectional view showing a state in which an inter-element 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] It is a cross-sectional view showing the state where the recording element was formed into a film in Comparative Example 2. [Figure 7E] It is a cross-sectional view showing the state where the photoresist was removed to form the recording element in Comparative Example 2. [Figure 7F] It is a cross-sectional view showing the state where the interlayer insulating layer and the magnetic body were formed in Comparative Example 2. [[ID=​​​​​​​​​​​​​​​​​​​​​​Although the thickness of the substrate 10 is not particularly limited, for example, it is 280 to 775 μm in accordance with JEITA or SEMI standards. In this specification, although the side on which each member is formed with respect to the substrate 10 will be 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 prevents etching. Therefore, according to the etching stopper layer 20, when providing an etching hole in the inter-element 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 composed 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, 3 to 5 nm is preferable in order to surely fulfill the role of preventing etching.

[0018] (Inter-element insulating layer) The inter-element insulating layer 30 is a layer formed on the etching stopper layer 20 and is a layer formed adjacent to the recording element 40 with the same thickness. The inter-element insulating layer 30 may be composed 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-element insulating layer 30 may be the same as that of the recording element 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 material that can be removed for the inter-element insulating layer 30 and a material that cannot be removed for the etching stopper layer 20, in other words, a combination that allows appropriate anisotropic etching. From this point of view, as described above, the etching stopper layer 20 is preferably made of MgO and the inter-element insulating layer 30 is preferably made of SiO2 or SiN X This combination is particularly preferred.

[0020] (recording element) The recording element 40 is a conductor formed on the etching stopper layer 20, and is formed adjacent to the inter-element insulating layer 30 with the same thickness and in a linear shape (specifically, a thin wire shape). The recording element 40 is arranged so as to be perpendicular to the longitudinal end (the left end in FIG. 1 ) of the magnetic body 60 when viewed from above. A recording current that magnetizes the magnetic body 60 is applied to this recording element 40. The recording element 40 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 40 is as described for the inter-element insulating layer 30.

[0021] (Relationship between inter-element insulating layer and recording element) By forming the inter-element insulating layer 30 of the same thickness adjacent to the recording element 40, it is possible to avoid the occurrence of a step corresponding to the thickness of the recording element 40. Furthermore, by making the top surfaces of the inter-element insulating layer 30 and the recording element 40 flush with each other, it is possible to form each member, such as the magnetic body 60, stacked thereon on a flat surface without any steps. Here, "coplanar" refers to a state in which the upper surfaces of the inter-element insulating layer 30 and the recording element 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] (Interlayer insulating layer) The interlayer insulating layer 50 is a layer formed on the recording element 40 and the interelement insulating layer 30, and is an insulating layer between the lower recording element 40 and the upper magnetic body 60 to insulate them from each other. The interlayer insulating layer 50 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 50 is not particularly limited, but is, for example, 25 to 40 nm.

[0023] (magnetic material) The magnetic body 60 is a magnetic member formed on the interlayer insulating layer 50 so as to be perpendicular to the recording element 40, and has a linear shape (specifically, a thin wire shape). This magnetic material 60 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.

[0024] More specifically, the magnetic body 60 includes a magnetic nanowire 61 and a topological insulator film 62, as shown in FIG. The magnetic fine wire 61 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 61 include FePt, FePd, etc., which are ordered alloys of the FePt system. The thickness of the magnetic nanowire 61 is, for example, 3 to 10 nm. The topological insulator film 62 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 62, the current density required to drive the magnetic domains can be significantly reduced, thereby realizing power saving.

[0025] In FIG. 1, the magnetic nanowire memory 100 includes two magnetic bodies 60, but the number of magnetic bodies 60 is not particularly limited. 2, the magnetic body 60 includes the magnetic wire 61 and the topological insulator film 62, but may further include other films. For example, a barrier layer made of MgO (see JP 2024-13615 A) may be provided between the magnetic wire 61 and the topological insulator film 62.

[0026] (playhead) The reproducing head 70 is an element that converts a magnetic signal into an electric signal. The reproducing head 70 is disposed above the longitudinal end (the right end in FIG. 1) of the magnetic body 60. 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.

[0027] (Other configurations) The magnetic nanowire memory 100 according to this embodiment may include a pair of electrodes connected to both ends of the magnetic body 60 in the longitudinal direction and serving as pads for applying a drive current. In addition, 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 60 and the recording current flowing through the recording element 40, a reproduction processing unit that processes signals from the reproduction head 70, and the like.

[0028] [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. (record) Recording is an operation of forming magnetic domains (information units) magnetized upward or downward in the magnetic body 60. The magnetic domains are formed by the magnetic field of the recording current applied to the recording element . (Drive) Driving is an operation that moves the magnetic domain in the longitudinal direction of the magnetic body 60 (shifting it in a direction away from the recording element 40). Driving is performed by applying a driving current to the magnetic body 60. 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 60 are aligned in the longitudinal direction, and binary information is stored in the magnetic body 60 as shown in FIG.

[0029] (reproduction) Reproduction is an operation of detecting the magnetization direction of the magnetic domain in the magnetic body 60. The detection of the magnetization direction is performed by the reproduction head 70. The reproduction head 70 detects the magnetization direction of the magnetic domain in the magnetic body 60 located below the member.

[0030] 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 top surfaces of the recording element 40 and the inter-element insulating layer 30 are flush with each other, and the magnetic body 60 (magnetic nanowire 61) spanning the boundary between the two members is formed on a flat surface. This prevents the magnetic body 60 (magnetic nanowire 61) from being subjected to unnecessary strain not only during manufacturing but also during operation, and reduces the possibility of breakage.

[0031] [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 FIG. 3, the method for manufacturing a magnetic nanowire memory according to this embodiment includes an etching stopper layer forming step S1, an inter-element insulating layer forming step S2, a recording element forming step S3 (S31 to S34), an inter-layer insulating layer forming step S4, and a magnetic material forming step S5. Each step of the method for manufacturing a magnetic nanowire memory according to this embodiment will be described in detail below.

[0032] (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.

[0033] (Inter-element insulating layer forming process: step S2) In the inter-element insulating layer forming step S2, the inter-element insulating layer 30 is formed on the etching stopper layer 20 by film deposition, as shown in FIG. 4B.

[0034] (Recording element formation process: step S3) In the recording element forming step S3 (S31 to S34), the recording elements 40 having the same thickness as the inter-element insulating layer 30 are formed in the same layer as the layer 30. 4C, photoresist R is first formed on the inter-element insulating layer 30 in a pattern in which gaps V are formed where the recording elements 40 are to be provided (S31). The patterning of the photoresist R may be performed by known photolithography, in which the photoresist R is uniformly formed on the inter-element 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 inter-element insulating layer 30 where no photoresist R is formed in top view (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 inter-element insulating layer 30 is made of SiO2 or SiN XIn this case, reactive ion etching using reactive gases such as CF4 and SF6 is preferred. Next, as shown in Fig. 4E, the recording element 40 is formed (S33). Finally, as shown in Fig. 4F, the photoresist R is peeled off to form the recording element 40 (S34). Through these steps, the recording element 40 can be formed in the same layer as the inter-element insulating layer 30 and has the same thickness as the layer 30. As a result, the upper surface of the inter-element insulating layer 30 and the upper surface of the recording element 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).

[0035] (Interlayer insulating layer forming process: step S4) In the interlayer insulating layer forming step S4, the interlayer insulating layer 50 is formed on the interelement insulating layer 30 and the recording element 40. Specifically, as shown in Fig. 4G, a photoresist R having a predetermined pattern is formed. Next, as shown in Fig. 4H, an interlayer insulating layer 50 is formed. Finally, as shown in Fig. 4I, the photoresist R is peeled off to form the interlayer insulating layer 50. The patterning and peeling of the photoresist R in the interlayer insulating layer forming step S4 is the same as in the recording element forming step S3.

[0036] (Magnetic body forming process: step S5) In the magnetic body forming step S5, the magnetic body 60 is formed on the interlayer insulating layer 50. Specifically, as shown in FIG. 4J, a photoresist R is formed in a predetermined pattern. Next, as shown in FIG. 4K, a magnetic body 60 is deposited. If the magnetic body 60 has a structure including both a magnetic nanowire 61 and a topological insulator film 62, then the two films may be deposited in the state shown in FIG. 4K. Finally, as shown in FIG. 4L, the photoresist R is peeled off to form the magnetic body 60. The patterning and peeling of the photoresist R in the magnetic material forming step S5 is the same as in the recording element forming step S3.

[0037] 4L, the interlayer insulating layer 50 and the magnetic body 60 are formed so as to straddle the boundary between the interelement insulating layer 30 and the recording element 40, but according to the manufacturing method described above, the upper surface of the interelement insulating layer 30 and the upper surface of the recording element 40 are flush with each other. As a result, the interlayer insulating layer 50 and the magnetic body 60 are formed on a flat surface without any steps at the boundary (the portion indicated by the dotted circle in FIG. 4L), which reduces the possibility of breakage of the magnetic body 60 (magnetic nanowire 61) and improves yield.

[0038] (Other processes) The method for manufacturing the magnetic nanowire memory according to this embodiment may include, after the magnetic body forming step S5, a step of forming a read head 70, a step of forming a pair of electrodes connected to both ends of the magnetic body 60, etc. as appropriate.

[0039] 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 inter-element insulating layer 30. As a result, the top surfaces of the recording element 40 and the inter-element insulating layer 30 can be formed to be flush with each other, and the magnetic body 60 (magnetic nanowire 61) spanning the boundary between the two components can be formed on a flat surface. This reduces the possibility of the magnetic body 60 (magnetic nanowire 61) breaking during manufacturing, and improves yield.

[0040] [Variations] Next, a modified example of the magnetic nanowire memory according to this embodiment will be described with reference to FIG. 5, the magnetic nanowire memory 101, which is a modified example, includes a pair of electrodes 80a, 80b for driving the magnetic domain of the magnetic body 60 in the same layer as the inter-element insulating layer 30 and the recording element 40. The magnetic nanowire memory 101 also includes an upper electrode 90 for the reproducing head on top of the reproducing head 70. The electrode 80b also serves as a lower electrode for the reproducing head. Furthermore, like the magnetic nanowire memory 100, the magnetic nanowire memory 101 has an etching stopper layer 20, so that not only the upper surfaces of the inter-element insulating layer 30 and the recording element 40 but also the upper surfaces of the pair of electrodes can be made "on the same plane." The pair of electrodes 80a, 80b may be formed in the same manner as the method for forming the recording element 40. In detail, the process of forming the electrodes may be carried out by the steps of forming a photoresist, forming etching holes in the inter-element insulating layer, depositing the electrodes, and peeling off the photoresist to form the electrodes.

[0041] 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.

[0042] [Comparative Example 1: Manufacturing method of magnetic nanowire memory without inter-element insulating layer] "Comparative Example 1: Manufacturing method of magnetic nanowire memory without inter-element insulating layer", which is a configuration in which the configuration of a conventional magnetic nanowire memory is inverted but no inter-element insulating layer is provided, will be described with reference to Figures 6A to 6C. First, a recording element 40 is formed on a substrate 10 (more specifically, a thermal oxide film 11) (FIG. 6A). Then, an interlayer insulating layer 50 is formed on the recording element 40 (FIG. 6B). Then, a magnetic body 60 is formed on the interlayer insulating layer 50 (FIG. 6C). The recording element 40, interlayer insulating layer 50, and magnetic body 60 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-element insulating layer," a steep step corresponding to the height (for example, several hundred nm) of the recording element 40 occurs in the area surrounded by the dotted circle in Fig. 6C. As a result, the magnetic body 60 spanning this steep step is highly likely to break.

[0043] 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 inter-element insulating layer is provided but no etching stopper layer is provided, will be described with reference to FIGS. 7A to 7F. First, an inter-element 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, a recording element 40 is deposited (FIG. 7D). Then, the photoresist R is peeled off to form the recording element 40 (FIG. 7E). Then, an interlayer insulating layer 50 and a magnetic body 60 are formed (FIG. 7F). The interlayer insulating layer 50 and the magnetic body 60 are formed by forming a photoresist in a predetermined pattern, depositing each material, and peeling off the photoresist. According to "Comparative Example 2: Manufacturing Method of Magnetic Nanowire Memory Without Etching Stopper Layer," the inter-element insulating layer 30 is provided, thereby preventing the occurrence of a step corresponding to the height of the recording element 40 (e.g., several hundred nm). However, in FIG. 7C, even if etching is performed to the thickness of the inter-element insulating layer 30, the etching process is time-controlled, resulting in variations in the depth of the etching hole H within a range of approximately ±10% (the dotted circle in FIG. 7C) even within the same substrate and the same lot. Therefore, even if a recording element 40 having the same thickness as the inter-element 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 60 (magnetic nanowire 61) spanning this step is more likely to break.

[0044] (Study based on comparison with Comparative Examples 1 and 2) According to the magnetic nanowire memory and its manufacturing method of this embodiment, an inter-element insulating layer 30 of the same thickness is formed adjacent to the recording element, so unlike "Comparative Example 1: Manufacturing method of magnetic nanowire memory without inter-element insulating layer", it is possible to avoid a situation where a steep step corresponding to the height of the recording element 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-element insulating layer" and "Comparative Example 2: Manufacturing method of magnetic nanowire memory without providing an etching stopper layer." [Explanation of symbols]

[0045] 10 Substrate 20 Etching stop layer 30 Inter-element insulating layer 40 Recording element 50 Interlayer insulation layer 60 Magnetic materials (magnetic nanowires + topological insulator films) 61 Magnetic thin wire 62 Topological insulator membrane 70 Playhead 100 Magnetic nanowire memory R Photoresist V Gap (where the recording element is located) H Etching hole 80a electrode 80b electrode 90 Upper electrode for read head 101 Magnetic nanowire memory (variation)

Claims

1. A substrate; an etching stopper layer formed on the substrate; a linear recording element formed on the etching stopper layer; an inter-element insulating layer formed on the etching stopper layer and adjacent to the recording element to the same thickness; an interlayer insulating layer formed on the recording element and the inter-element insulating layer; a magnetic nanowire formed on the interlayer insulating layer so as to be perpendicular to the recording element; a topological insulator film formed on 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 surface of the recording element and the upper surface of the inter-element 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 inter-element 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-element insulating layer on the etching stopper layer; forming an area for forming a linear recording element in the inter-element insulating layer by etching; forming a recording element in the region with the same thickness as the inter-element insulating layer; forming an interlayer insulating layer on the recording element and the inter-element insulating layer; forming a magnetic nanowire on the interlayer insulating layer so as to be perpendicular to the recording element, and forming a topological insulator film on 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 surface of the inter-element insulating layer and the upper surface of the recording element 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 inter-element 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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