Magnetic domain wall moving element and magnetic storage array

Abstract

The invention provides a magnetic domain wall moving element with high reliability and a magnetic memory array. A magnetic domain wall moving element according to the present embodiment has a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer laminated in this order from the side closer to a substrate, and has a thickness of 1-10 [mu] m on a cut surface cut in a second direction orthogonal to a first direction in which the first ferromagnetic layer extends in plan view from the lamination direction. The shortest width of the first ferromagnetic layer in the second direction is shorter than the width of the non-magnetic layer in the second direction.

Description

[0001] (This application is a divisional application of a patent application with a filing date of May 24, 2021, application number 202110565671.2, and invention name “Magnetic Domain Wall Moving Element and Magnetic Storage Array”.) Technical Field

[0002] The invention relates to a magnetic domain wall moving element and a magnetic storage array. Background Art

[0003] Next-generation nonvolatile memories that replace flash memory and other memories that have reached their limits in miniaturization are attracting much attention. Examples of next-generation nonvolatile memories include MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistance Randome Access Memory), and PCRAM (Phase Change Random Access Memory).

[0004] MRAM uses the change in resistance value caused by the change in magnetization direction for data storage. Data storage is performed by each of the magnetoresistive change elements that constitute the MRAM. For example, Patent Document 1 describes a three-terminal magnetoresistive effect element that separates the paths of write current and read current.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Patent Publication No. 6275806 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] Sometimes, a process called slimming is performed when miniaturizing a magnetoresistance element. Thinning is a process in which an ion beam is irradiated to the side of the magnetoresistance element to reduce the top-view area of ​​the magnetoresistance element. However, if the ion beam is irradiated to the exposed metal surface, sometimes part of the metal will fly away and attach to the side wall of the magnetoresistance element again. Impurities attached to the side wall of the magnetoresistance element degrade the magnetic properties of the ferromagnetic material that constitutes the magnetoresistance element. In addition, the attached impurities also become a cause of leakage of the magnetoresistance element. Impurities attached to the side wall of the magnetoresistance element will reduce the reliability of the magnetoresistance element.

[0010] The present invention has been made in view of the above-mentioned problems, and provides a magnetoresistive element and a magnetic memory array with high reliability.

[0011] Means for solving technical problems

[0012] (1) A first type of magnetic domain wall moving element comprises a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer stacked in sequence from a side close to a substrate, and when viewed from above in the stacking direction, on a cut surface cut along a second direction orthogonal to a first direction in which the first ferromagnetic layer extends, the shortest width of the first ferromagnetic layer in the second direction is shorter than the width of the non-magnetic layer in the second direction.

[0013] (2) In the domain wall moving element of the above aspect, in a cross section taken along the stacking direction and the second direction, the side surface of the first ferromagnetic layer may be inclined with respect to the stacking direction.

[0014] (3) On the cross-section along the stacking direction and the second direction of the magnetic domain wall movement element of the above-mentioned manner, the side surface of the first ferromagnetic layer may have a first inclined surface and a second inclined surface, the first inclined surface is inclined from the lower end of the first ferromagnetic layer on the side close to the substrate toward the center of the first ferromagnetic layer in the second direction, and the second inclined surface is inclined from the upper end of the first ferromagnetic layer on the side away from the substrate toward the center of the first ferromagnetic layer in the second direction.

[0015] (4) In the magnetic domain wall moving element of the above aspect, the width of the first surface of the first ferromagnetic layer on the nonmagnetic layer side in the second direction may be shorter than the width of the nonmagnetic layer in the second direction.

[0016] (5) In the magnetic domain wall moving element of the above aspect, a position where the width of the first ferromagnetic layer in the second direction is shortest may be located closer to the nonmagnetic layer than a center of the first ferromagnetic layer in the stacking direction.

[0017] (6) In the magnetic domain wall moving element of the above aspect, the longest width of the first ferromagnetic layer in the second direction may be shorter than the width of the nonmagnetic layer in the second direction.

[0018] (7) In the magnetic domain wall moving element of the above aspect, a width of a second surface of the first ferromagnetic layer on a side away from the nonmagnetic layer in the second direction may be greater than a width of the nonmagnetic layer in the second direction.

[0019] (8) In the above-mentioned magnetic domain wall moving element, the thickness of the non-magnetic layer may be above.

[0020] (9) In the magnetic domain wall moving element of the above aspect, a milling rate of the nonmagnetic layer may be lower than a milling rate of the first ferromagnetic layer.

[0021] (10) The magnetic domain wall moving element of the above aspect may further include an underlayer on the side of the first ferromagnetic layer opposite to the nonmagnetic layer, and the underlayer may be cut at a lower rate than the first ferromagnetic layer.

[0022] (11) It may also be that the first ferromagnetic layer of the magnetic domain wall movement element of the above-mentioned method contains an element constituting the base layer, and regarding the abundance of the element, a first region which is closer to the base layer side than the position where the width of the first ferromagnetic layer in the second direction is shortest in the stacking direction is more concentrated than a second region which is closer to the nonmagnetic layer side than the position where the width of the first ferromagnetic layer in the second direction is shortest in the stacking direction.

[0023] (12) The magnetic domain wall moving element of the above-mentioned manner may also have a first conductive portion and a second conductive portion which sandwich the nonmagnetic layer along the first direction and are electrically connected to the first ferromagnetic layer via the base layer, wherein the width of each of the first conductive portion and the second conductive portion in the second direction is wider than the width of the first ferromagnetic layer in the second direction, and the milling rate of the base layer is slower than the milling rate of the first conductive portion and the second conductive portion.

[0024] (13) The magnetic domain wall moving element of the above aspect may further include a metal layer different from the second ferromagnetic layer on the side of the second direction of the second ferromagnetic layer.

[0025] (14) A magnetic memory array according to a second aspect includes a plurality of magnetic domain wall moving elements according to the above aspect.

[0026] Effects of the Invention

[0027] The magnetic domain wall moving element and magnetic memory array of the above-described embodiment have excellent reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural diagram of the magnetic memory array according to the first embodiment.

[0029] Figure 2 It is a cross-sectional view of a characteristic portion of the magnetic memory array according to the first embodiment.

[0030] Figure 3 1 is an xz cross-sectional view of the magnetic domain wall moving element according to the first embodiment.

[0031] Figure 4 It is a top view of the magnetic domain wall moving element of the first embodiment.

[0032] Figure 5 It is a yz cross-sectional view at the center of the magnetic domain wall moving element in the x direction according to the first embodiment.

[0033] Figure 6 It is a yz cross-sectional view in the first conductive portion of the magnetic domain wall moving element according to the first embodiment.

[0034] Figure 7 This is a schematic diagram for explaining the thinning when manufacturing the magnetic domain wall moving element according to the first embodiment.

[0035] Figure 8 1 is a yz cross-sectional view of the center of the magnetic domain wall moving element in the x direction according to the first modification.

[0036] Fig. 9 1 is a yz cross-sectional view of the center of the magnetic domain wall moving element in the x direction according to the second modification.

[0037] Fig.10 1 is a yz cross-sectional view of the center of the magnetic domain wall moving element in the x direction according to the third modification.

[0038] Fig.11 1 is an xz cross-sectional view of the magnetic domain wall moving element according to the first embodiment.

[0039] Fig.12 It is a yz cross-sectional view at the center of the magnetic domain wall moving element in the x direction according to the first embodiment.

[0040] Explanation of symbols

[0041] 10, 70...First ferromagnetic layer

[0042] 10a, 70a...Page 1

[0043] 10b, 70b...side 2

[0044] 20, 80... Second ferromagnetic layer

[0045] 30...Non-magnetic layer

[0046] 40...basal layer

[0047] 51……first conductive part

[0048] 52... Second conductive portion

[0049] 60...Metal layer

[0050] 100, 101, 102, 103, 104... magnetic domain wall moving element

[0051] 200...Magnetic Storage Array

[0052] L10max...Longest Width

[0053] L10min... shortest width

[0054] L30...Width

[0055] R1…The first area

[0056] R2...Second Area

[0057] s1...the first inclined surface

[0058] s2... the second inclined surface

[0059] s3... inclined surface DETAILED DESCRIPTION

[0060] Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings as appropriate. In order to make the features of the present invention easy to understand, the accompanying drawings used in the following description sometimes enlarge the features to show the parts, and the dimensional ratios of the components are sometimes different from the actual ones. The materials, dimensions, etc. illustrated in the following description are examples, and the present invention is not limited to them, and can be implemented by appropriately changing within the scope of achieving the effects of the present invention.

[0061] First, the directions are defined. The x direction and the y direction are related to the substrate Sub (see Figure 2 ) on one side. The x direction is the direction in which the first ferromagnetic layer 10 described later extends, and is the direction from the first conductive portion 51 described later toward the second conductive portion 52. The y direction is a direction orthogonal to the x direction. The z direction is the direction from the substrate Sub described later toward the magnetic domain wall moving element 100. The z direction is an example of a stacking direction. In addition, in this specification, "extending along the x direction" means, for example, that the dimension in the x direction is larger than the smallest dimension among the dimensions in the x direction, the y direction, and the z direction. The same applies to extensions in other directions.

[0062] [First embodiment]

[0063] Figure 1 1 is a structural diagram of a magnetic memory array according to the first embodiment. The magnetic memory array 200 includes a plurality of magnetic domain wall moving elements 100, a plurality of first wirings Wp1 to Wpn, a plurality of second wirings Cm1 to Cmn, a plurality of third wirings Rp1 to Rpn, a plurality of first switching elements 110, a plurality of second switching elements 120, and a plurality of third switching elements 130. The magnetic memory array 200 can be used, for example, for a magnetic memory, a multiplier accumulator, or a neuromorphic device.

[0064] 〈First wiring, second wiring, third wiring〉

[0065] The first wirings Wp1 to Wpn are write wirings. The first wirings Wp1 to Wpn electrically connect a power source to one or more magnetic domain wall moving elements 100. The power source is connected to one end of the magnetic memory array 200 when in use.

[0066] The second wirings Cm1 to Cmn are common wirings. Common wirings are wirings that can be used for both writing and reading data. The second wirings Cm1 to Cmn electrically connect a reference potential to one or more magnetic domain wall moving elements 100. The reference potential is, for example, a ground line. The second wirings Cm1 to Cmn can be provided in each of the plurality of magnetic domain wall moving elements 100, or can be provided throughout the plurality of magnetic domain wall moving elements 100.

[0067] The third wirings Rp1 to Rpn are read wirings. The third wirings Rp1 to Rpn electrically connect a power source to one or more magnetic domain wall moving elements 100. The power source is connected to one end of the magnetic memory array 200 when in use.

[0068] <First switching element, second switching element, third switching element>

[0069] Figure 1 The first switching element 110, the second switching element 120, and the third switching element 130 shown are connected to each of the plurality of magnetic domain wall moving elements 100. The first switching element 110 is connected between each of the magnetic domain wall moving elements 100 and the first wirings Wp1 to Wpn. The second switching element 120 is connected between each of the magnetic domain wall moving elements 100 and the second wirings Cm1 to Cmn. The third switching element 130 is connected between each of the magnetic domain wall moving elements 100 and the third wirings Rp1 to Rpn.

[0070] When the first switch element 110 and the second switch element 120 are turned on, a write current flows between the first wirings Wp1 to Wpn and the second wirings Cm1 to Cmn connected to a predetermined magnetic domain wall moving element 100. When the second switch element 120 and the third switch element 130 are turned on, a read current flows between the second wirings Cm1 to Cmn and the third wirings Rp1 to Rpn connected to a predetermined magnetic domain wall moving element 100.

[0071] The first switch element 110, the second switch element 120, and the third switch element 130 are elements for controlling the flow of current. The first switch element 110, the second switch element 120, and the third switch element 130 are, for example, transistors, elements using phase changes of crystal layers such as a bidirectional threshold switch (OTS), elements using changes in energy band structure such as a metal insulator transition (MIT) switch, elements using breakdown voltage such as a Zener diode and an avalanche breakdown diode, and elements whose conductivity changes with changes in atomic positions.

[0072] Any of the first switch element 110, the second switch element 120, and the third switch element 130 may be shared in the magnetic domain wall moving element 100 connected to the same wiring. For example, when the first switch element 110 is shared, one first switch element 110 is provided upstream of the first wirings Wp1 to Wpn. For example, when the second switch element 120 is shared, one second switch element 120 is provided upstream of the second wirings Cm1 to Cmn. For example, when the third switch element 130 is shared, one third switch element 130 is provided upstream of the third wirings Rp1 to Rpn.

[0073] Figure 2 It is a cross-sectional view of a characteristic portion of the magnetic memory array 200 according to the first embodiment. Figure 2 The xz plane is cut along the center of the width of the first ferromagnetic layer 10 in the y direction. Figure 1 FIG. 1 is a cross section of a magnetic domain wall moving element 100 .

[0074] Figure 2 The first switching element 110 and the second switching element 120 shown are transistors Tr. The transistor Tr has a gate electrode G, a gate insulating film GI, a source region S and a drain region D formed on a substrate Sub. The substrate Sub is, for example, a semiconductor substrate. The third switching element 130 is electrically connected to the electrode E, for example, in the depth direction (+y direction) of the paper.

[0075] Each of the transistors Tr and the magnetic domain wall moving element 100 are electrically connected via a wiring W. The wiring W includes a material having conductivity. The wiring W extends, for example, in the z direction. The wiring W is, for example, a through-hole wiring formed in an opening portion of the insulating layer In.

[0076] The magnetic domain wall moving element 100 and the transistor Tr are electrically separated by the insulating layer In except for the wiring W. The insulating layer In is an insulating layer for insulating the wirings of the multilayer wiring or the elements. The insulating layer In is made of, for example, silicon oxide (SiO x), Silicon Nitride (SiN x ), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO x )wait.

[0077] "Domain wall moving element"

[0078] Figure 3 1 is a cross-sectional view of the magnetic domain wall moving element 100 cut along an xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. Figure 4 This is a diagram showing the magnetic domain wall moving element 100 as viewed from above in the z direction. Figure 5 The cross-sectional view is a view of the magnetic domain wall moving element 100 cut along a yz plane passing through the center of the magnetic domain wall moving element 100 in the x direction. Figure 5 It is along Figure 4 The AA line cuts off a cross section of the magnetic domain wall moving element 100 . Figure 6 It is a cross-sectional view of the magnetic domain wall moving element 100 cut along a yz plane passing through the first conductive portion 51 of the magnetic domain wall moving element 100 . Figure 6 It is along Figure 4 Line BB cuts off a cross section of the magnetic domain wall moving element 100 .

[0079] The magnetic domain wall moving element 100 includes, for example, a first ferromagnetic layer 10, a second ferromagnetic layer 20, a nonmagnetic layer 30, a base layer 40, a first conductive portion 51, and a second conductive portion 52. For example, the first ferromagnetic layer 10, the nonmagnetic layer 30, and the second ferromagnetic layer 20 are stacked in order from the side close to the substrate Sub. Other layers may be inserted between the first ferromagnetic layer 10 and the nonmagnetic layer 30 and between the nonmagnetic layer 30 and the second ferromagnetic layer 20. When writing data to the magnetic domain wall moving element 100, a write current is passed through the first ferromagnetic layer 10 between the first conductive portion 51 and the second conductive portion 52. When reading data from the magnetic domain wall moving element 100, a read current is passed between the first conductive portion 51 or the second conductive portion 52 and the second ferromagnetic layer 20.

[0080] “First ferromagnetic layer”

[0081] The first ferromagnetic layer 10 extends in the x direction. A write current is passed through the first ferromagnetic layer 10. The first ferromagnetic layer 10 is, for example, a rectangle with the x direction as the major axis and the y direction as the minor axis when viewed from the z direction. The first ferromagnetic layer 10 is, for example, located closer to the substrate Sub than the second ferromagnetic layer 20. The write current flows along the first ferromagnetic layer 10 from the first conductive portion 51 toward the second conductive portion 52 or from the second conductive portion 52 toward the first conductive portion 51.

[0082] The first ferromagnetic layer 10 is a layer capable of magnetically storing information by changing the internal magnetic state. The first ferromagnetic layer 10 is sometimes referred to as a magnetic storage layer or a magnetic domain wall migration layer.

[0083] like Figure 3 As shown, the first ferromagnetic layer 10 has, for example, magnetization fixed regions 11 and 12 and a magnetic domain wall movement region 13. The magnetic domain wall movement region 13 is sandwiched by the two magnetization fixed regions 11 and 12, for example, in the x-direction.

[0084] The magnetization fixed region 11 is a region overlapping the first conductive portion 51 of the first ferromagnetic layer 10 when viewed from the z direction. The magnetization fixed region 12 is a region overlapping the second conductive portion 52 of the first ferromagnetic layer 10 when viewed from the z direction. 11 、M 12 The magnetization M of the domain wall movement region 13 13A 、M 13B In contrast, it is not easy to reverse the magnetization, even if the magnetization M of the magnetic domain wall movement region 13 is applied. 13A 、M 13B Therefore, the magnetization M of the magnetization fixed regions 11 and 12 is 11 、M 12 It can be said that the magnetization M of the magnetic domain wall movement region 13 13A 、M 13B fixed.

[0085] The magnetization M of the magnetization fixing region 11 11 and the magnetization M of the magnetization fixing region 12 12 The magnetization M of the magnetization fixed region 11 is oriented in different directions. 11 and the magnetization M of the magnetization fixing region 12 12 For example, they are oriented in opposite directions. 11 For example, the magnetization M of the magnetization fixing region 12 is oriented in the +z direction. 12 For example, oriented along the -z direction.

[0086] The magnetic domain wall moving region 13 is composed of a first magnetic region 13A and a second magnetic region 13B. The first magnetic region 13A is adjacent to the magnetization fixed region 11. The magnetization M of the first magnetic region 13A 13A The magnetization M of the magnetized fixed region 11 11 For example, along with the magnetization M of the magnetization fixed region 11 11 The second magnetic region 13B is adjacent to the magnetization fixed region 12. The magnetization M of the second magnetic region 13B 13B The magnetization M of the magnetized fixed region 12 12 The influence of, for example, the magnetization M along with the magnetization fixed region 1212 Therefore, the magnetization M of the first magnetic region 13A is 13A and the magnetization M of the second magnetic region 13B 13B The magnetization M of the first magnetic region 13A is oriented in different directions. 13A and the magnetization M of the second magnetic region 13B 13B For example, oriented in opposite directions.

[0087] The boundary between the first magnetic region 13A and the second magnetic region 13B is a magnetic domain wall DW. The magnetic domain wall DW moves in the magnetic domain wall moving region 13. In principle, the magnetic domain wall DW does not invade the magnetization fixed regions 11 and 12.

[0088] In the magnetic domain wall moving region 13, the magnetic domain wall DW moves by passing a write current in the x direction of the magnetic domain wall moving region 13. For example, if a write current (e.g., a current pulse) in the +x direction is applied to the magnetic domain wall moving region 13, electrons flow in the -x direction opposite to the current, and thus the magnetic domain wall DW moves in the -x direction. When the current flows from the first magnetic region 13A toward the second magnetic region 13B, the spin-polarized electrons in the second magnetic region 13B cause the magnetization M of the first magnetic region 13A to move. 13A The magnetization M of the first magnetic region 13A is reversed. 13A The magnetization reversal is performed, and the magnetic domain wall DW moves in the -x direction. In the magnetic domain wall moving region 13, when the magnetic domain wall moves, the ratio of the first magnetic region 13A to the second magnetic region 13B changes.

[0089] In the magnetic domain wall moving region 13, if the magnetic domain wall DW moves, the ratio of the first magnetic region 13A to the second magnetic region 13B changes, and the resistance of the magnetic domain wall moving element 100 changes according to the ratio of the first magnetic region 13A to the second magnetic region 13B. In addition, if the position of the magnetic domain wall DW is moved in stages, the resistance value of the magnetic domain wall moving element 100 changes in stages, and if the position of the magnetic domain wall DW is moved continuously, the resistance value of the magnetic domain wall moving element 100 changes continuously. The magnetic domain wall moving element 100 whose resistance value changes in stages is suitable for processing multi-value data. The magnetic domain wall moving element 100 whose resistance value changes continuously is suitable for processing analog data.

[0090] like Figure 5 and Figure 6 As shown, the shortest width L10min of the first ferromagnetic layer 10 in the y direction is shorter than the width L30 in the y direction of the nonmagnetic layer 30. The width L30 in the y direction of the nonmagnetic layer 30 is the average value of the widths in the y direction, and when the widths in the y direction vary depending on the position in the z direction, for example, it refers to their average value.

[0091] Figure 5 and Figure 6The width of the first ferromagnetic layer 10 shown in the y direction varies depending on the position in the z direction. For example, the width of the first surface 10a and the second surface 10b of the first ferromagnetic layer 10 are different in the y direction. The first surface 10a is the surface of the first ferromagnetic layer 10 on the non-magnetic layer 30 side. The second surface 10b is the surface of the first ferromagnetic layer 10 on the opposite side of the first surface 10a.

[0092] Figure 5 and Figure 6 The width of the first surface 10 a in the y direction is shown to be the same as the width L30 of the nonmagnetic layer 30 in the y direction. Figure 5 and Figure 6 The width of the first ferromagnetic layer 10 in the y direction becomes narrower from the first surface 10a toward the second surface 10b, and then becomes wider after reaching the shortest width L10min. The shortest width L10min is located closer to the nonmagnetic layer 30 than the center of the first ferromagnetic layer 10 in the z direction. Figure 5 and Figure 6 The width of the first ferromagnetic layer 10 in the y direction is longest on the second surface 10 b . Figure 5 and Figure 6 The width of the second surface 10b in the y direction is shown to be longer than the width L30 in the y direction of the nonmagnetic layer 30. The maximum width L10max in the y direction of the first ferromagnetic layer 10 is longer than the width L30 in the y direction of the nonmagnetic layer 30, for example.

[0093] Figure 5 and Figure 6 The side surface of the first ferromagnetic layer 10 shown in the y direction is inclined in the y direction relative to the z direction. The side surface of the first ferromagnetic layer 10 in the y direction can be divided into a first inclined surface s1 and a second inclined surface s2. The first inclined surface s1 is an inclined surface inclined toward the center of the first ferromagnetic layer 10 in the y direction with the lower end of the side surface of the substrate Sub of the first ferromagnetic layer 10 as a reference. The second inclined surface s2 is an inclined surface inclined toward the center of the first ferromagnetic layer 10 in the y direction with the upper end of the side surface of the first ferromagnetic layer 10 on the non-magnetic layer 30 as a reference. The second inclined surface s2 is overhanging relative to the first inclined surface s1.

[0094] The first inclined surface s1 and the second inclined surface s2 sandwich an inflection point p1 where the inclination of the tangent line of the side surface of the first ferromagnetic layer 10 with respect to the z direction becomes zero. The inflection point p1 is located further inside than the end of the non-magnetic layer 30 in the y direction. The side surface of the first ferromagnetic layer 10 in the y direction is, for example, recessed relative to an imaginary plane descending from the end of the non-magnetic layer 30 in the y direction in the z direction.

[0095] The first ferromagnetic layer 10 is composed of a magnetic body. The first ferromagnetic layer 10 preferably has at least one element selected from Co, Ni, Fe, Pt, Pd, Gd, Tb, Mn, Ge, and Ga. As materials for the first ferromagnetic layer 10, for example, a stacked film of Co and Ni, a stacked film of Co and Pt, a stacked film of Co and Pd, a MnGa system material, a GdCo system material, and a TbCo system material can be cited. The saturation magnetization of ferromagnets such as MnGa system materials, GdCo system materials, and TbCo system materials is small, and the threshold current required to move the magnetic domain wall DW becomes small. In addition, the coercive force of the stacked film of Co and Ni, the stacked film of Co and Pt, and the stacked film of Co and Pd is large, and the moving speed of the magnetic domain wall DW is slow.

[0096] The first ferromagnetic layer 10 may also include an element constituting the base layer 40. In terms of element abundance, for example, a first region R1 located closer to the base layer 40 than the position where the first ferromagnetic layer 10 has the shortest width L10min in the z direction is richer than a second region R2 located closer to the nonmagnetic layer 30 than the position where the first ferromagnetic layer 10 has the shortest width L10min in the z direction.

[0097] "Non-magnetic layer"

[0098] The nonmagnetic layer 30 is in contact with the first ferromagnetic layer 10, for example. The nonmagnetic layer 30 is located on the first ferromagnetic layer 10. The nonmagnetic layer 30 is located between the first ferromagnetic layer 10 and the second ferromagnetic layer 20.

[0099] The non-magnetic layer 30 is composed of, for example, a non-magnetic insulator, a semiconductor or a metal. Examples of non-magnetic insulators include Al2O3, SiO2, MgO, MgAl2O4 and materials in which a portion of Al, Si and Mg is replaced by Zn, Be and the like. These materials have large band gaps and excellent insulating properties. When the non-magnetic layer 30 is composed of a non-magnetic insulator, the non-magnetic layer 30 is a tunnel barrier layer. Examples of non-magnetic metals include Cu, Au, Ag and the like. Examples of non-magnetic semiconductors include Si, Ge, CuInSe2, CuGaSe2, Cu(In,Ga)Se2 and the like.

[0100] The milling rate of the non-magnetic layer 30 is slower than the milling rate of the first ferromagnetic layer 10, for example. The milling rate is a milling rate for dry etching. For example, ion beam etching is used in dry etching. In ion beam etching, in milling accelerated by a voltage of several hundred to several kV, for example, a rare gas element such as Ar, Kr, Xe or its ions can be used. In the case where the non-magnetic layer 30 is an oxide, the milling rate is generally slower than that of the first ferromagnetic layer 10, which is a metal.

[0101] The thickness of the non-magnetic layer 30 is preferably More preferably If the thickness of the non-magnetic layer 30 is thick, the resistance area product (RA) of the domain wall moving element 100 becomes large. The resistance area product (RA) of the domain wall moving element 100 is preferably 1×10 4 Ωμm 2 More preferably, 1×10 5 Ωμm 2 The resistance area product (RA) of the domain wall moving element 100 is represented by the product of the element resistance of one domain wall moving element 100 and the element cross-sectional area of ​​the domain wall moving element 100 (the area of ​​the cross section of the nonmagnetic layer 30 cut along the xy plane).

[0102] In addition, due to the fact that the non-magnetic layer 30 is thick and the difference in milling rate from other layers during thinning, there is a tendency for impurities to easily reattach to the side walls of the non-magnetic layer 30. If the relationship between the width L30 of the non-magnetic layer 30 in the y direction and the shortest width L10min of the first ferromagnetic layer 10 in the y direction is controlled, even if the non-magnetic layer 30 is thick, the reattachment of impurities to the side walls of the non-magnetic layer 30 can be suppressed.

[0103] "Second ferromagnetic layer"

[0104] The second ferromagnetic layer 20 is located on the nonmagnetic layer 30. The second ferromagnetic layer 20 has a magnetization M oriented in one direction. 20 The magnetization M of the second ferromagnetic layer 20 20 When a predetermined external force is applied, the magnetization M of the domain wall movement region 13 13A 、M 13B The predetermined external force is, for example, an external force applied to magnetization by an external magnetic field or an external force applied to magnetization by a spin polarized current. The second ferromagnetic layer 20 is sometimes referred to as a magnetization fixed layer or a magnetization reference layer.

[0105] Due to the magnetization of the second ferromagnetic layer 20 and the magnetization M of the magnetic domain wall movement region 13 13A 、M 13B The relative angle of the first magnetic region 13A is different, so that the resistance value of the magnetic domain wall moving element 100 changes. 13A For example, the magnetization M of the second ferromagnetic layer 20 20 The same direction (parallel), the magnetization M of the second magnetic region 13B 13B For example, the magnetization M of the second ferromagnetic layer 20 20In the opposite direction (antiparallel). If the area of ​​the first magnetic region 13A in the portion overlapping with the second ferromagnetic layer 20 as viewed from the z direction is enlarged, the resistance value of the magnetic domain wall moving element 100 is reduced. Conversely, if the area of ​​the second magnetic region 13B in the portion overlapping with the second ferromagnetic layer 20 as viewed from the z direction is enlarged, the resistance value of the magnetic domain wall moving element 100 is increased.

[0106] The second ferromagnetic layer 20 includes a ferromagnetic material. For example, the second ferromagnetic layer 20 includes a material that easily obtains a coherent tunnel effect between the first ferromagnetic layer 10 and the second ferromagnetic layer 20. The second ferromagnetic layer 20 includes, for example, a metal selected from Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, and an alloy containing these metals and at least one element of B, C, and N. For example, the second ferromagnetic layer 20 is Co-Fe, Co-Fe-B, or Ni-Fe.

[0107] The second ferromagnetic layer 20 may also be, for example, a Heusler alloy. A Heusler alloy is a semimetal having a high spin polarization rate. A Heusler alloy is an intermetallic compound having a chemical composition of XYZ or X2YZ, where X is a transition metal element or a noble metal element of the Co, Fe, Ni, or Cu group in the periodic table, Y is a transition metal of the Mn, V, Cr, or Ti group or an element of X, and Z is a typical element of group III to group V. Examples of Heusler alloys include Co2FeSi, Co2FeGe, Co2FeGa, Co2MnSi, Co2Mn 1-a Fe a Al b Si 1-b 、Co2FeGe 1-c Ga c wait.

[0108] When the easy magnetization axis of the second ferromagnetic layer 20 is set in the z direction (set as a perpendicular magnetization film), the film thickness of the second ferromagnetic layer 20 is preferably set to 1.5 nm or less, and more preferably set to 1.0 nm or less. If the film thickness of the second ferromagnetic layer 20 is thinned, perpendicular magnetic anisotropy (interface perpendicular magnetic anisotropy) is added to the second ferromagnetic layer 20 at the interface between the second ferromagnetic layer 20 and other layers (non-magnetic layer 30), and the magnetization of the second ferromagnetic layer 20 is easily oriented in the z direction.

[0109] When the easy magnetization axis of the second ferromagnetic layer 20 is set in the z direction (set as a perpendicular magnetization film), the second ferromagnetic layer 20 is preferably set as a laminate of a ferromagnetic material selected from Co, Fe, and Ni and a non-magnetic material selected from Pt, Pd, Ru, and Rh, and more preferably an intermediate layer selected from Ir and Ru is inserted at any position of the laminate. If the ferromagnetic material and the non-magnetic material are laminated, perpendicular magnetic anisotropy can be added, and the magnetization of the second ferromagnetic layer 20 is easily oriented in the z direction by inserting the intermediate layer.

[0110] An antiferromagnetic layer may also be provided on the surface of the second ferromagnetic layer 20 on the side opposite to the non-magnetic layer 30 via a spacer layer. The second ferromagnetic layer 20, the spacer layer, and the antiferromagnetic layer form a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a non-magnetic layer. The second ferromagnetic layer 20 and the antiferromagnetic layer are antiferromagnetically coupled, and the coercive force of the second ferromagnetic layer 20 becomes larger than that without the antiferromagnetic layer. The antiferromagnetic layer is, for example, IrMn, PtMn, etc. The spacer layer contains, for example, at least one selected from Ru, Ir, and Rh.

[0111] The base layer 40 is located on the opposite side of the first ferromagnetic layer 10 from the nonmagnetic layer 30. The base layer 40 may be located only at a position overlapping with the magnetic domain wall movement region 13 in the z direction.

[0112] The base layer 40 is composed of a non-magnetic body. The base layer 40, for example, defines the crystal structure of the first ferromagnetic layer 10. Compared with the crystal structure of the base layer 40, the crystallinity of the first ferromagnetic layer 10 is improved, and the orientation of the magnetization of the first ferromagnetic layer 10 is improved. The crystal structure of the base layer 40 is, for example, amorphous, (001)-oriented NaCl structure, (002)-oriented perovskite structure represented by the composition formula of ABO3, (001)-oriented tetragonal structure or cubic structure.

[0113] The base layer 40 is a conductor or an insulator. The base layer 40 is preferably a conductor. When the base layer 40 is a conductor, the thickness of the base layer 40 is preferably thinner than the thickness of the first ferromagnetic layer 10. The base layer 40 includes, for example, Ta, Ru, Pt, Ir, Rh, W, Pd, Cu, Au, Cu. The base layer 40 is, for example, a Ta layer, a Pt layer, or a stack of a Ta layer and a Pt layer.

[0114] The milling rate of the base layer 40 is, for example, slower than that of the first ferromagnetic layer 10. In addition, the milling rate of the base layer 40 is, for example, slower than that of the first conductive portion 51 and the second conductive portion 52. For example, the base layer 40 contains one or more elements selected from Al, Cr, Mg, Ta, Ti, and W, the first ferromagnetic layer 10 contains one or more elements selected from Co, Fe, Ni, Pt, Pd, Ir, and Rh, and the first conductive portion 51 and the second conductive portion 52 are alloys or laminates containing one or more elements selected from Au, Cu, and Ru. Specifically, for example, the base layer is Ta or a laminated film of Ta and Pt, the first ferromagnetic layer 10 is a laminated film of Co and Pt, and the first conductive portion 51 and the second conductive portion 52 are Au.

[0115] The thickness of the base layer 40 is, for example, substantially constant in the xy plane. The average thickness of the base layer 40 is, for example, The average thickness is the average value of the thickness of the base layer 40 measured at positions in the x direction of each of ten portions into which the base layer 40 is divided at equal intervals in the x direction.

[0116] “First conductive portion and second ferromagnetic portion”

[0117] The first conductive portion 51 and the second conductive portion 52 are electrically connected to the first ferromagnetic layer 10. The first conductive portion 51 and the second conductive portion 52 are, for example, Figure 6 As shown, the first conductive portion 51 and the second conductive portion 52 are connected via the base layer 40. The first conductive portion 51 and the second conductive portion 52 may also be directly connected to the first ferromagnetic layer 10. The first conductive portion 51 is connected to the first end of the first ferromagnetic layer 10, for example, and the second conductive portion 52 is connected to the second end of the first ferromagnetic layer 10, for example. The first conductive portion 51 and the second conductive portion 52 are, for example, connecting portions of the wiring W and the first ferromagnetic layer 10.

[0118] The first conductive part 51 and the second conductive part 52 are columnar. When viewed from the z direction, Figure 4 The first conductive portion 51 and the second conductive portion 52 shown in the figure are rectangular in shape. The shape of the first conductive portion 51 and the second conductive portion 52 when viewed from the z direction may be circular, elliptical, or amorphous. The width of the first conductive portion 51 and the second conductive portion 52 in the y direction is, for example, wider than the width of the first ferromagnetic layer 10 and the non-magnetic layer 30 in the y direction. The upper surfaces of the first conductive portion 51 and the second conductive portion 52 are, for example, etched and recessed relative to the xy plane.

[0119] The first conductive part 51 and the second conductive part 52 are made of a conductive material. The first conductive part 51 and the second conductive part 52 include, for example, a magnetic body. The first conductive part 51 and the second conductive part 52 include, for example, a metal selected from Cr, Mn, Co, Fe and Ni, an alloy containing one or more of these metals, and an alloy containing these metals and at least one element of B, C and N. The first conductive part 51 and the second conductive part 52 are, for example, Co-Fe, Co-Fe-B, Ni-Fe, etc. In addition, when the easy magnetization axis of the first conductive part 51 and the second conductive part 52 is set to the z direction (set as a perpendicular magnetization film), it is preferred that the first conductive part 51 and the second conductive part 52 are set to a laminate of a ferromagnetic body selected from Co, Fe, and Ni and a non-magnetic body selected from Pt, Pd, Ru, and Rh. In addition, the first conductive part 51 and the second conductive part 52 may also be a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a non-magnetic layer. The magnetizations of the two magnetic layers are fixed, and the directions of the fixed magnetizations are opposite.

[0120] When the first conductive portion 51 includes a magnetic body, the magnetization M of the first conductive portion 51 is 51 Oriented in one direction. Magnetization M 51 For example, the first conductive portion 51 is oriented in the +z direction. 11 The magnetization M of the first conductive portion 51 51 and the magnetization M of the magnetization fixed region 11 11 For example oriented in the same direction.

[0121] When the second conductive portion 52 includes a magnetic body, the magnetization M of the second conductive portion 52 52 Along with the magnetization M of the first conductive portion 51 51 Oriented in opposite directions. Magnetization M 52 For example, the second conductive portion 52 is oriented in the −z direction. In this case, the second conductive portion 52 fixes the magnetization M of the magnetization fixing region 12. 12 , the magnetization M of the second conductive portion 52 52 and the magnetization M of the magnetization fixing region 12 12 For example oriented in the same direction.

[0122] The magnetization direction of each layer of the domain wall moving element 100 can be confirmed by measuring a magnetization curve, for example. The magnetization curve can be measured using MOKE (Magneto Optical Kerr Effect). The measurement based on MOKE is a measurement method that is performed by causing linear polarization to be incident on the measurement object and using a magneto-optical effect (magnetic Kerr effect) that causes the rotation of the polarization direction.

[0123] Next, a method for manufacturing the magnetic memory array 200 is described. The magnetic memory array 200 is formed by a stacking process of each layer and a processing process of processing a portion of each layer into a predetermined shape. The stacking of each layer can be performed using a sputtering method, a chemical vapor growth (CVD) method, an electron beam evaporation method (EB evaporation method), an atomic laser deposition method, etc. The processing of each layer can be performed using a photolithography method, etc.

[0124] First, impurities are doped at predetermined positions of the substrate Sub to form a source region S and a drain region D. Next, a gate insulating film GI and a gate electrode G are formed between the source region S and the drain region D. The source region S, the drain region D, the gate insulating film GI and the gate electrode G form a transistor Tr.

[0125] Next, an insulating layer In is formed so as to cover the transistor Tr. In addition, an opening is formed in the insulating layer In and a conductor is filled in the opening to form the wiring W. The first wiring Wp and the second wiring Cm are formed by forming a groove in the insulating layer In after laminating the insulating layer In to a predetermined thickness and filling the groove with a conductor.

[0126] The first conductive portion 51 and the second conductive portion 52 can be formed, for example, by laminating a ferromagnetic layer on one surface of the insulating layer In and the wiring W and removing portions other than the portions to be the first conductive portion 51 and the second conductive portion 52. The removed portions are filled with the insulating layer In, for example.

[0127] Next, the base layer 40, the first ferromagnetic layer 10, and the non-magnetic layer 30 are stacked in this order on the first conductive portion 51, the second conductive portion 52, and the insulating layer In. In addition, a resist is formed on a portion of the non-magnetic layer 30. Next, dry etching is performed from the z direction through the resist to process the base layer 40, the first ferromagnetic layer 10, and the non-magnetic layer 30. The yz cross-sectional shape of the processed laminate is a rectangle or a trapezoid.

[0128] Next, the first ferromagnetic layer 10 of the stack is irradiated with an ion beam from an oblique direction. The first ferromagnetic layer 10 is dented toward the center of the stack in the y direction by the ion beam irradiation. Then, the second ferromagnetic layer 20 is stacked at a position overlapping the first ferromagnetic layer 10.

[0129] Finally, the stack is thinned as a whole by reducing the irradiation angle of the ion beam relative to the xy plane and irradiating the stack with the ion beam from the lateral direction. The stack is miniaturized by thinning. Finally, the surrounding of the stack is buried with an insulating layer In to obtain the magnetic domain wall moving element 100.

[0130] When the magnetic domain wall moving element 100 of the first embodiment is thinned, it is difficult for impurities to adhere to the side surface of the non-magnetic layer 30 again. Figure 7 The reason is explained. Figure 7 This is a schematic diagram for explaining the thinning when manufacturing the magnetic domain wall moving element 100 according to the first embodiment.

[0131] As described above, when thinning, the stacked body composed of the base layer 40, the first ferromagnetic layer 10, the non-magnetic layer 30, and the second ferromagnetic layer 20 is irradiated with the ion beam IB from the y direction. It is difficult to irradiate the ion beam IB in parallel with the y direction, and the ion beam IB is irradiated from a direction slightly inclined to the z direction relative to the xy plane. For example, if the first ferromagnetic layer 10 is irradiated with the ion beam IB, the metal particles contained in the first ferromagnetic layer 10 are scattered as particles pt.

[0132] In the magnetic domain wall moving element 100 of the first embodiment, since the shortest width L10min of the first ferromagnetic layer 10 in the y direction is shorter than the width L30 of the nonmagnetic layer 30 in the y direction, the nonmagnetic layer 30 becomes a cover, which can inhibit the particles pt from attaching to the side wall of the nonmagnetic layer 30 again.

[0133] In addition, if the first ferromagnetic layer 10 has a second inclined surface s2, the second inclined surface s2 is cantilevered relative to the first inclined surface s1, and therefore, it is possible to further suppress the particle pt from reaching the side wall of the non-magnetic layer 30. In addition, if the position where the width of the first ferromagnetic layer 10 in the y direction becomes the shortest is located closer to the non-magnetic layer 30 than the center of the first ferromagnetic layer 10 in the z direction, the portion close to the non-magnetic layer 30 is recessed inward, and it is possible to further suppress the particle pt from reaching the side wall of the non-magnetic layer 30.

[0134] In addition, if the milling rate of the non-magnetic layer 30 and the base layer 40 is made slower than that of the first ferromagnetic layer 10, the side surface of the first ferromagnetic layer 10 moves inward relative to the side surface of the non-magnetic layer 30 and the base layer 40 as the thinning progresses. Therefore, the non-magnetic layer 30 becomes a cover, and it is possible to further suppress the particles pt from attaching to the side wall of the non-magnetic layer 30 again. In addition, if the milling rate of the base layer 40 is made slower than that of the first conductive portion 51 and the second conductive portion 52, the base layer 40 becomes a cover, and it is possible to further suppress the particles pt scattered from the first conductive portion 51 or the second conductive portion 52 from reaching the side wall of the non-magnetic layer 30.

[0135] In addition, if the first ferromagnetic layer 10 contains an element constituting the base layer 40, it is possible to reduce the amount of particles pt scattered from the first ferromagnetic layer 10. In addition, by making the abundance of the element constituting the base layer 40 in the first region R1 higher than that in the second region R2, it is possible to suppress the generation of particles pt from the first region R1 where it is easy to ensure a path for the particles pt to reach the non-magnetic layer 30.

[0136] Impurities formed by the attached particles reduce the MR ratio of the domain wall moving element 100 and may short-circuit the first ferromagnetic layer 10 and the second ferromagnetic layer 20. The domain wall moving element 100 of the first embodiment can reduce the attachment of impurities to the side wall of the nonmagnetic layer 30, so it has high reliability.

[0137] An example of the magnetic memory array 200 and the magnetic domain wall moving element 100 according to the first embodiment has been described in detail above. However, the magnetic memory array 200 and the magnetic domain wall moving element 100 according to the first embodiment can be variously modified and altered within the scope of the present invention.

[0138] (First Modification)

[0139] Figure 8 1 is a yz cross-sectional view of the center of the x direction of the magnetic domain wall moving element 101 of the first modification. The shape of the side surface of the first ferromagnetic layer 10 of the magnetic domain wall moving element 101 is different from that of the magnetic domain wall moving element 100. In the magnetic domain wall moving element 101, the same reference numerals are given to the same structures as those of the magnetic domain wall moving element 100, and the description thereof is omitted.

[0140] Figure 8 The side surface of the first ferromagnetic layer 10 in the y direction is an inclined surface s3 inclined in the y direction relative to the z direction. The inclined surface s3 is an inclined surface inclined away from the center of the first ferromagnetic layer 10 in the y direction with respect to the upper end of the side surface of the first ferromagnetic layer 10 on the non-magnetic layer 30 side as a reference.

[0141] Figure 8 The width of the first surface 10 a in the y direction is shown to be shorter than the width L30 of the nonmagnetic layer 30 in the y direction. Figure 8 The width of the first ferromagnetic layer 10 in the y direction increases from the first surface 10 a toward the second surface 10 b . Figure 8 The width of the first ferromagnetic layer 10 in the y direction is shortest on the first surface 10 a and longest on the second surface 10 b .

[0142] In the magnetic domain wall moving element 101 of the first modification, a portion of the side surface in the y direction of the first ferromagnetic layer 10 is located inside the nonmagnetic layer 30. Therefore, the nonmagnetic layer 30 serves as an eave, and it is possible to suppress the particles pt scattered from the first ferromagnetic layer 10 from attaching to the side wall of the nonmagnetic layer 30 again.

[0143] (Second Modification)

[0144] Fig. 91 is a yz cross-sectional view at the center of the x direction of the magnetic domain wall moving element 102 of the second modification. The shape of the side surface of the first ferromagnetic layer 10 of the magnetic domain wall moving element 102 is different from that of the magnetic domain wall moving element 100. In the magnetic domain wall moving element 102, the same reference numerals are given to the same structures as those of the magnetic domain wall moving element 100, and the description thereof is omitted.

[0145] The magnetic domain wall moving element 102 of the second modified example is the same as the magnetic domain wall moving element 100 in that the width of the first ferromagnetic layer 10 in the y direction is the longest on the second surface 10b, but is different in that the width of the second surface 10b in the y direction is shorter than the width L30 of the non-magnetic layer 30 in the y direction. In the magnetic domain wall moving element 102 of the second modified example, for example, the maximum width L10max of the first ferromagnetic layer 10 in the y direction is shorter than the width L30 of the non-magnetic layer 30 in the y direction.

[0146] In the domain wall moving element 102 of the second modification, the side surface of the first ferromagnetic layer 10 in the y direction is located inside the nonmagnetic layer 30. Therefore, the nonmagnetic layer 30 serves as an eaves, and the particles pt scattered from the first ferromagnetic layer 10 can be prevented from attaching to the side wall of the nonmagnetic layer 30 again.

[0147] (Third Modification)

[0148] Fig.10 1 is a yz cross-sectional view of the third modified example at the center of the x direction of the magnetic domain wall moving element 103. The magnetic domain wall moving element 103 is different from the magnetic domain wall moving element 100 in that the metal layer 60 is provided on the side surface of the second ferromagnetic layer 20. In the magnetic domain wall moving element 103, the same reference numerals are given to the same structures as those of the magnetic domain wall moving element 100, and the description thereof is omitted.

[0149] The metal layer 60 is, for example, located on the y-direction side of the second ferromagnetic layer 20. The metal layer 60 is, for example, in contact with the y-direction side of the second ferromagnetic layer 20. Another layer may exist between the second ferromagnetic layer 20 and the metal layer 60. The other layer is, for example, an oxide film.

[0150] The metal layer 60 is not continuous with the second ferromagnetic layer 20. Not continuous means that the interface can be confirmed by a transmission electron microscope. The metal layer 60 is different from the second ferromagnetic layer 20. Different from the second ferromagnetic layer 20 means that the material or composition is different. The metal layer 60 can be a non-magnetic body or a magnetic body.

[0151] The domain wall moving element 103 of the third modification can obtain the same effects as the domain wall moving element 100 of the first embodiment. In addition, since the metal layer 60 protrudes outward from the first ferromagnetic layer 10, the heat dissipation of the domain wall moving element 103 is improved.

[0152] "Second Implementation Method"

[0153] Fig.11 This is a cross-sectional view of the magnetic domain wall moving element 104 according to the second embodiment cut along an xz plane passing through the center of the first ferromagnetic layer 70 in the y direction. Fig.12 The cross-sectional view of the magnetic domain wall moving element 104 is cut along the yz plane passing through the center of the magnetic domain wall moving element 104 in the x direction. Figure 4 same.

[0154] The magnetic domain wall moving element 104 includes, for example, a first ferromagnetic layer 70, a second ferromagnetic layer 80, a nonmagnetic layer 30, a base layer 40, a first conductive portion 51, and a second conductive portion 52. In the magnetic domain wall moving element 104, the same reference numerals are used for the same structures as those in the first embodiment. The first ferromagnetic layer 70 is located closer to the substrate Sub than the second ferromagnetic layer 80.

[0155] When writing data to the domain wall moving element 104, a write current flows through the second ferromagnetic layer 80 between the first conductive portion 51 and the second conductive portion 52. When reading data from the domain wall moving element 100, a read current flows between the first conductive portion 51 or the second conductive portion 52 and the first ferromagnetic layer 70.

[0156] The first ferromagnetic layer 70 has a magnetization M oriented in one direction. 70 The first ferromagnetic layer 70 is a magnetization fixed layer and a magnetization reference layer. The first ferromagnetic layer 70 is functionally equivalent to the second ferromagnetic layer 20 of the first embodiment. The magnetic domain wall moving element 104 is a bottom pin structure in which the magnetization fixed layer is on the substrate Sub side. The first ferromagnetic layer 70 can use the same material as the second ferromagnetic layer 20. The first ferromagnetic layer 70 may also contain elements constituting the base layer 40.

[0157] A write current is passed through the second ferromagnetic layer 80. The second ferromagnetic layer 80 has the same function as the first ferromagnetic layer 10 of the first embodiment. The second ferromagnetic layer 80 can be made of the same material as the first ferromagnetic layer 10.

[0158] The second ferromagnetic layer 80 is a layer capable of magnetically storing information by changing the magnetic state inside. The second ferromagnetic layer 80 is sometimes referred to as a magnetic storage layer or a magnetic domain wall moving layer. The second ferromagnetic layer 80 has magnetization fixed regions 81 and 82 and a magnetic domain wall moving region 83. The magnetization M of the magnetization fixed region 81 is 81 and the magnetization M of the magnetization fixing region 82 82The magnetic domain wall moving region 83 has a first magnetic region 83A and a second magnetic region 83B. The boundary between the first magnetic region 83A and the second magnetic region 83B is a magnetic domain wall DW. 83A and magnetization M 84A The magnetic domain walls DW are oriented in opposite directions.

[0159] like Fig.12 As shown, the shortest width L70min of the first ferromagnetic layer 70 in the y direction is shorter than the width L30 of the non-magnetic layer 30 in the y direction. The width of the first ferromagnetic layer 70 in the y direction varies depending on the position in the z direction. For example, the widths in the y direction of the first surface 70a and the second surface 70b of the first ferromagnetic layer 70 are different. The width in the y direction of the first ferromagnetic layer 70 becomes narrower as it moves from the first surface 10a toward the second surface 10b, and becomes wider after reaching the shortest width L70min. The position where the shortest width L70min is obtained is, for example, closer to the non-magnetic layer 30 side than the center of the first ferromagnetic layer 10 in the z direction. The longest width L70max of the first ferromagnetic layer 70 in the y direction is, for example, longer than the width L30 of the non-magnetic layer 30 in the y direction.

[0160] The side surface of the first ferromagnetic layer 70 in the y direction is inclined in the y direction relative to the z direction, for example. The side surface of the first ferromagnetic layer 70 in the y direction can be divided into a first inclined surface s1 and a second inclined surface s2. The side surface of the first ferromagnetic layer 70 in the y direction is, for example, recessed relative to an imaginary plane descending from the end of the non-magnetic layer 30 in the y direction in the z direction.

[0161] The milling rate of the nonmagnetic layer 30 is, for example, slower than the milling rate of the first ferromagnetic layer 70. The milling rate of the base layer 40 is, for example, slower than the milling rate of the first ferromagnetic layer 70.

[0162] In the magnetic domain wall moving element 104 of the second embodiment, since the shortest width L70min of the first ferromagnetic layer 70 in the y direction is shorter than the width L30 of the non-magnetic layer 30 in the y direction, the non-magnetic layer 30 becomes a cover, which can suppress the particles pt from attaching to the side wall of the non-magnetic layer 30 again. The magnetic domain wall moving element 104 of the second embodiment achieves the same effect as the magnetic domain wall moving element 100 of the first embodiment. In addition, the magnetic domain wall moving element 104 of the second embodiment can select the same modified example as the first embodiment.

[0163] The preferred embodiments of the present invention have been described in detail above, but the characteristic structures in the respective embodiments and modifications may be combined.

Claims

1. A magnetic domain wall moving element, characterized in that: A first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer are sequentially stacked from the side close to the substrate. When viewed from above in the stacking direction, on a cross section cut along a second direction perpendicular to a first direction in which the first ferromagnetic layer extends, The shortest width of the first ferromagnetic layer in the second direction is shorter than the width of the nonmagnetic layer in the second direction. The first direction is along the long axis direction of the first ferromagnetic layer when viewed from the stacking direction, and the second direction is along the short axis direction of the first ferromagnetic layer when viewed from the stacking direction. A write current flows along the first direction of the second ferromagnetic layer.

2. The magnetic domain wall moving element according to claim 1, characterized in that: In a cut surface along the stacking direction and the second direction, a side surface of the first ferromagnetic layer is inclined with respect to the stacking direction.

3. The magnetic domain wall moving element according to claim 2, characterized in that: On a cut surface along the stacking direction and the second direction, the side surface of the first ferromagnetic layer has a first inclined surface and a second inclined surface, The first inclined surface is inclined from a lower end of the first ferromagnetic layer on a side close to the substrate toward a center of the first ferromagnetic layer in the second direction. The second inclined surface is inclined from an upper end of the first ferromagnetic layer on a side away from the substrate toward a center of the first ferromagnetic layer in the second direction.

4. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: A width of a first surface of the first ferromagnetic layer on the nonmagnetic layer side in the second direction is shorter than a width of the nonmagnetic layer in the second direction.

5. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: A position where the width of the first ferromagnetic layer in the second direction is shortest is located closer to the nonmagnetic layer than the center of the first ferromagnetic layer in the stacking direction.

6. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: The longest width of the first ferromagnetic layer in the second direction is shorter than the width of the nonmagnetic layer in the second direction.

7. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: A width of a second surface of the first ferromagnetic layer on a side away from the nonmagnetic layer in the second direction is longer than a width of the nonmagnetic layer in the second direction.

8. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: The thickness of the non-magnetic layer is above.

9. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: The nonmagnetic layer is milled at a slower rate than the first ferromagnetic layer.

10. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: The first ferromagnetic layer further includes a base layer on the side opposite to the non-magnetic layer. The base layer is milled at a slower rate than the first ferromagnetic layer.

11. The magnetic domain wall moving element according to claim 10, characterized in that: The first ferromagnetic layer includes an element constituting the base layer, Regarding the abundance of the element, a first region located closer to the base layer than a position where the width of the first ferromagnetic layer in the second direction is shortest in the stacking direction is denser than a second region located closer to the nonmagnetic layer than a position where the width of the first ferromagnetic layer in the second direction is shortest in the stacking direction.

12. The magnetic domain wall moving element according to any one of claims 1 to 3, characterized in that: A metal layer different from the second ferromagnetic layer is further provided on the side of the second ferromagnetic layer in the second direction.

13. A magnetic storage array comprising a plurality of magnetic domain wall moving elements according to any one of claims 1 to 12.

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