Method of operating magnetic memory device

Abstract

A method of operating a magnetic memory device includes (i) applying a first current to a free layer of a magnetic tunnel junction structure including a magnetic conversion unit (MTU) extending between a first magnetic pad and a second magnetic pad, and a tunnel barrier layer and a pinning layer stacked on the MTU such that multiple domains are established within the MTU, (ii) applying a magnetic field to the free layer, and (ii) applying a second current to the free layer. And (iv) applying a magnetic field to the free layer such that the magnetization direction of the MTU is switched to become antiparallel to the magnetization directions of the first and second magnetic pads, (iii) applying a second current to the free layer such that a portion of the multi-domain permeates into the first magnetic pad, and (iv) applying another magnetic field to the free layer such that the magnetization direction of the first magnetic pad is switched to become antiparallel to the magnetization direction of the second magnetic pad.

Description

[0001] Citation of priority application

[0002] This application claims priority to Korean Patent Application No. 10-2023-0093344, filed on Jul. 18, 2023, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The inventive concept relates to a method of operating a memory device, and more particularly, to a method of operating a magnetic memory device. Background Art

[0004] Miniaturized, multifunctional, and high-performance electronic products require high-capacity memory devices. A racetrack memory (RM) has been proposed as a high-capacity memory device, which may include a plurality of magnetic domains that store information according to the movement of magnetic domain walls between magnetic domains. In addition, a magnetic domain wall shift register type memory device including a racetrack has been developed. However, in order to realize a magnetic memory device that supports stable movement of magnetic domain walls and high integration, various problems must be solved. Summary of the invention

[0005] The inventive concept provides a method of operating a magnetic memory device which can be easily initialized using a more simplified process and efficient operation.

[0006] According to one aspect of the inventive concept, a method for operating a magnetic memory device is provided, which includes preparing a magnetic track layer, the magnetic track layer including a first magnetic fixed unit, a second magnetic fixed unit, and a magnetic conversion unit extending in a horizontal direction between the first magnetic fixed unit and the second magnetic fixed unit. A first magnetic field is applied to the magnetic track layer so that the first magnetic fixed unit, the second magnetic fixed unit, and the magnetic conversion unit have magnetization directions parallel to each other. A first current is applied to the magnetic track layer so that a multi-domain is formed in the magnetic conversion unit. In addition, a second magnetic field is applied to the magnetic track layer so that the magnetization direction of the magnetic conversion unit becomes antiparallel to the magnetization direction of the first magnetic fixed unit and the second magnetic fixed unit. A second current is applied to the magnetic track layer so that a portion of the multi-domain penetrates into the first magnetic fixed unit. Next, a third magnetic field is applied to the magnetic track layer so that the magnetization direction of the first magnetic fixed unit becomes antiparallel to the magnetization direction of the second magnetic fixed unit.

[0007] According to another aspect of the inventive concept, a method for operating a magnetic memory device is provided, the magnetic memory device being used to fix the magnetization direction of a first magnetic pad and the magnetization direction of a second magnetic pad to an antiparallel state relative to each other. The operating method includes preparing a magnetic tunnel junction structure, the magnetic tunnel junction structure including a free layer, a tunnel barrier layer and a pinning layer, a magnetic conversion unit being arranged between the first magnetic pad and the second magnetic pad in a horizontal direction, and the tunnel barrier layer and the pinning layer each extending in a vertical direction on the magnetic conversion unit. A first magnetic field is applied to the free layer so that the first magnetic pad, the second magnetic pad and the magnetic conversion unit have magnetization directions parallel to each other. A first current is applied to the free layer so that a multi-domain is formed in the magnetic conversion unit. A second magnetic field is applied to the free layer so that the magnetization direction of the magnetic conversion unit becomes antiparallel to the magnetization direction of the first magnetic pad and the second magnetic pad. A second current is applied to the free layer so that a portion of the multi-domain penetrates into the first magnetic pad. A third magnetic field is applied to the free layer so that the magnetization direction of the first magnetic pad becomes antiparallel to the magnetization direction of the second magnetic pad.

[0008] In another method of operating a magnetic memory device according to an embodiment, a magnetic tunnel junction structure is provided, which includes a stacked structure of a free layer, a tunnel barrier layer, and a pinned layer. The free layer includes a first magnetic pad, a second magnetic pad, and a magnetic conversion unit extending in a horizontal direction between the first magnetic pad and the second magnetic pad. A magnetic field pulse is applied to the free layer three times, and a current pulse is applied to the free layer twice, so as to fix the magnetization direction of the first magnetic pad and the magnetization direction of the second magnetic pad to an antiparallel state relative to each other.

[0009] A method for operating a magnetic memory device according to another embodiment includes applying a first current to a free layer of a magnetic tunnel junction structure, the magnetic tunnel junction structure including a magnetic conversion unit (MTU) extending between a first magnetic pad and a second magnetic pad, and a tunnel barrier layer and a pinning layer stacked on the MTU, so that a multi-domain is established within the MTU. A magnetic field is applied to the free layer so that the magnetization direction of the MTU switches to become antiparallel to the magnetization direction of the first magnetic pad and the second magnetic pad. A second current is applied to the free layer so that a portion of the multi-domain penetrates into the first magnetic pad. Then, another magnetic field is applied to the free layer so that the magnetization direction of the first magnetic pad switches to become antiparallel to the magnetization direction of the second magnetic pad. In these embodiments, the free layer may be a magnetic track layer, and the first magnetic pad, the magnetic conversion unit, and the second magnetic pad may be configured to have a bow-tie shape when viewed from a planar layout perspective. And, according to some other embodiments, the operating method may include fixing the magnetization direction of the first magnetic pad and the magnetization direction of the second magnetic pad to an antiparallel state relative to each other, and then reading the magnetization direction of the MTU using a magnetic tunnel junction structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0011] Figure 1 is a perspective view illustrating main elements of a magnetic memory device according to an embodiment;

[0012] Figure 2 It is schematically shown Figure 1 A plan view of a free layer in a magnetic memory device;

[0013] Figure 3 is a flowchart illustrating an operating method of a magnetic memory device according to an embodiment;

[0014] FIG. 4A to FIG. 4E are plan views sequentially illustrating an operating method of a magnetic memory device according to an embodiment;

[0015] Figure 5 and Figure 6 is a table showing the magnetization direction based on the magnetic field and current field;

[0016] 7A to 7C is an electron microscope photograph showing initialization of a magnetic memory device according to an embodiment;

[0017] Figure 8 is a flow chart showing an algorithm of a magnetic memory device according to an embodiment; and

[0018] Fig. 9 is a block diagram illustrating an electronic system including a magnetic memory device according to an embodiment. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

[0020] Figure 1 1 is a perspective view showing main elements of a magnetic memory device 10 according to an embodiment. Figure 1 , the magnetic memory device 10 may include a magnetic track layer 110, a tunnel barrier layer 120, a pinned layer 130, and a conductive layer 140. The magnetic track layer 110 may have a linear shape having a long axis extending in a first horizontal direction X parallel to an upper surface of the magnetic track layer 110 and a short axis extending in a second horizontal direction Y perpendicular to the first horizontal direction X. In some embodiments, the magnetic track layer 110 may have a linear track extending in the first horizontal direction X. Herein, the magnetic track layer 110 may be referred to as a free layer.

[0021] The magnetic track layer 110 may include at least one metal material of cobalt (Co), iron (Fe), and nickel (Ni). In addition, the magnetic track layer 110 may also include at least one of non-magnetic materials such as boron (B), zinc (Zn), aluminum (Al), titanium (Ti), ruthenium (Ru), tantalum (Ta), silicon (Si), silver (Ag), gold (Au), copper (Cu), carbon (C), and nitrogen (N). The magnetic track layer 110 may include a plurality of magnetic domains and a plurality of magnetic domain walls. The plurality of magnetic domains and the plurality of magnetic domain walls may be alternately and repeatedly arranged in the first horizontal direction X.

[0022] The magnetic domain may be a region where the magnetization direction is uniform in the magnetic track layer 110, and the magnetic domain wall may be a region where the magnetization direction changes between the magnetic domains of the magnetic track layer 110. Each of the magnetic domain walls may define a boundary between magnetic domains having different magnetization directions among the magnetic domains. The size and magnetization direction of the magnetic domain may be appropriately controlled by the shape, size, and external energy of the magnetic track layer 110. The magnetic domain wall may be moved by a magnetic field or current applied to the magnetic track layer 110.

[0023] In the magnetic memory device 10 according to the embodiment, the magnetic track layer 110 may include a first magnetic fixed unit 111, a second magnetic fixed unit 112, and a magnetic conversion unit 113 disposed between the first magnetic fixed unit 111 and the second magnetic fixed unit 112. In this document, the first magnetic fixed unit 111 may be referred to as a first magnetic domain or a first magnetic pad. In addition, the second magnetic fixed unit 112 may be referred to as a second magnetic domain or a second magnetic pad. That is, although not shown, the magnetic domain wall may be disposed between the first magnetic fixed unit 111 and the magnetic conversion unit 113 and between the second magnetic fixed unit 112 and the magnetic conversion unit 113, respectively.

[0024] The tunnel barrier layer 120 may be disposed on the upper surface of the magnetic track layer 110. In some embodiments, the tunnel barrier layer 120 may be disposed on the magnetic conversion unit 113. For example, the tunnel barrier layer 120 may include at least one of magnesium (Mg) oxide, Ti oxide, Al oxide, Mg-Zn oxide, and Mg-B oxide. Next, the pinned layer 130 may be disposed on the upper surface of the tunnel barrier layer 120. In some embodiments, the pinned layer 130 may be disposed on the magnetic conversion unit 113. In other words, the pinned layer 130 may overlap with the magnetic conversion unit 113 in the vertical direction Z, wherein the tunnel barrier layer 120 extends therebetween.

[0025] The pinned layer 130 may include a ferromagnetic material. In addition, the pinned layer 130 may also include an antiferromagnetic material for fixing the magnetization direction of the ferromagnetic material. For example, the pinned layer 130 may include at least one metal material among Co, Fe and Ni, and may also include at least one of non-magnetic materials such as B, Zn, Al, Ti, Ru, Ta, Si, Ag, Au, Cu, C and N. Here, the pinned layer 130 is shown as a single-layer structure, but this may be only an embodiment, and the embodiment is not limited thereto. In some embodiments, the pinned layer 130 may be provided as a synthetic antiferromagnetic (SAF) structure. In addition, in the accompanying drawings, each of the pinned layer 130 and the tunnel barrier layer 120 is shown in a rectangular parallelepiped shape, but the embodiment is not limited thereto. For example, each of the pinned layer 130 and the tunnel barrier layer 120 may have a cylindrical shape.

[0026] The conductive layer 140 may be disposed on the lower surface of the magnetic track layer 110. In some embodiments, the first conductive layer 141 may be disposed below the first magnetic fixed unit 111, and the second conductive layer 142 may be disposed below the second magnetic fixed unit 112. In addition, the conductive layer 140 may include an induction layer that allows the generation of a spin-orbit torque (SOT) using a current flowing in the conductive layer 140. In other embodiments, the conductive layer 140 may include a material that allows the use of a current flowing in the conductive layer 140 in the first horizontal direction X or in a direction opposite to the first horizontal direction X to realize a spin Hall effect or a Rashba effect. In other words, the conductive layer 140 may be configured as a spin Hall conductive layer. In addition, the conductive layer 140 may include a heavy metal with an atomic number of 30 or more. For example, the conductive layer 140 may include iridium (Ir), Ru, Ta, platinum (Pt), palladium (Pd), bismuth (Bi), Ti, or tungsten (W), but is not limited thereto.

[0027] In the magnetic memory device 10 according to the embodiment, the magnetic track layer 110, the tunnel barrier layer 120 and the pinned layer 130 may configure a magnetic tunnel junction (MTJ) structure. Here, the magnetic track layer 110 may be referred to as a free layer. As will be understood by those skilled in the art, the magnetization direction of the pinned layer 130 may be fixed, and based on the stored data, the magnetization direction of the magnetic track layer 110 may be an antiparallel direction relative to the magnetization direction of the pinned layer 130.

[0028] In some embodiments, when the magnetic track layer 110 and the pinned layer 130 of the MTJ structure are in a parallel state, that is, when the MTJ structure has a low resistance, the parallel state can be defined as a data 0 (zero) state. On the other hand, when the magnetic track layer 110 and the pinned layer 130 of the MTJ structure are in an anti-parallel state, that is, when the MTJ structure has a high resistance, the anti-parallel state can be defined as a data 1 (one) state. However, these designations can be swapped. Therefore, in other embodiments, when the magnetic track layer 110 and the pinned layer 130 of the MTJ structure are in an anti-parallel state, this can be defined as a data 0 state, and when the magnetic track layer 110 and the pinned layer 130 of the MTJ structure are in a parallel state, this can be defined as a data 1 state.

[0029] In detail, the pinned layer 130 may overlap the magnetic switching unit 113 of the magnetic track layer 110 in the vertical direction Z. Therefore, in the magnetic memory device 10 according to the embodiment, the MTJ structure may read data based on the magnetization direction of the magnetic switching unit 113 .

[0030] Here, in the uninitialized magnetic memory device 10, the magnetization direction of each of the magnetic domains configuring the magnetic track layer 110 may be randomly formed, and thus may be parallel or anti-parallel to the magnetization direction of the pinned layer 130. That is, the magnetization direction of each of the first magnetic pinned unit 111 and the second magnetic pinned unit 112, each constituting the magnetic track layer 110, may be randomly formed. Therefore, the original magnetization direction of each of the first magnetic pinned unit 111 and the second magnetic pinned unit 112 may be parallel or anti-parallel to the magnetization direction of the pinned layer 130.

[0031] Therefore, an initialization process may be required to fix the first magnetic fixed unit 111 and the second magnetic fixed unit 112, each having a random state, to a desired magnetization direction. That is, in the initialization process, the magnetization direction of the first magnetic fixed unit 111 and the magnetization direction of the second magnetic fixed unit 112 can be fixed to an antiparallel state relative to each other. Therefore, the magnetic conversion unit 113 can change between stable magnetic states (i.e., fixed states), and therefore, the operation of a stable magnetic junction structure for a read and write process can be performed. This initialization operation method will be described in detail below.

[0032] Figure 2 It is schematically shown Figure 1 A plan view of a free layer in a magnetic memory device 10. Figure 2, the magnetic track layer 110 may include a first magnetic fixed unit 111, a second magnetic fixed unit 112, and a magnetic conversion unit 113 disposed between the first magnetic fixed unit 111 and the second magnetic fixed unit 112. The magnetic track layer 110 may be disposed such that the first magnetic fixed unit 111 contacts one side surface of the magnetic conversion unit 113, and the second magnetic fixed unit 112 contacts the other side surface of the magnetic conversion unit 113. As shown in the figure, the magnetic track layer 110 may be regarded as a free layer, wherein the first magnetic fixed unit 111, the magnetic conversion unit 113, and the second magnetic fixed unit 112 have a bow-tie shape parallel to the first horizontal direction X.

[0033] For example, the magnetic conversion unit 113 may have a straight line shape that extends long in the first horizontal direction X and has a certain width in the second horizontal direction Y perpendicular to the first horizontal direction X. In addition, the first magnetic fixing unit 111 and the second magnetic fixing unit 112 may be disposed at both ends of the magnetic conversion unit 113 and may have a trapezoidal shape, wherein the first magnetic fixing unit 111 and the second magnetic fixing unit 112 are mirror-symmetrical to each other.

[0034] An angle A1 between a virtual line L1 extending along the side wall of the end of the magnetic conversion unit 113 and a hypotenuse L2 having a trapezoidal shape of the second magnetic fixed unit 112 may be configured to be greater than 0 degrees and less than 90 degrees. For example, the angle A1 may be set to 45 degrees. Based on the shape of the magnetic track layer 110, the multi-domains of the magnetic conversion unit 113 may be easily moved to the first magnetic fixed unit 111 and the second magnetic fixed unit 112. In other words, the area of ​​each of the first magnetic fixed unit 111 and the second magnetic fixed unit 112 may be expanded from the boundary surface between the first magnetic fixed unit 111 and the magnetic conversion unit 113, and therefore, the resistance may be reduced so that the multi-domains may be more easily moved in the boundary surface.

[0035] Figure 3 is a flowchart showing an operation method S10 of a magnetic memory device according to an embodiment. Figure 3 , the operation method S10 of the magnetic memory device may include a process sequence of the first operation S110 to the sixth operation S160. In the case where some embodiments can be implemented differently, a specific operation sequence may be performed differently from the described sequence. For example, two operations described in succession may be performed substantially simultaneously, or may be performed in an order opposite to the described order.

[0036] The operating method S10 of the magnetic memory device according to the embodiment may include: a first operation S110 of preparing a magnetic track layer, the magnetic track layer including a first magnetic fixed unit, a second magnetic fixed unit, and a magnetic conversion unit disposed between the first magnetic fixed unit and the second magnetic fixed unit in a horizontal direction, and a second operation S120 of applying a first magnetic field to the magnetic track layer so that the first magnetic fixed unit, the second magnetic fixed unit, and the magnetic conversion unit have magnetization directions parallel to each other, a third operation S130 of applying a first current to the magnetic track layer so that a multi-domain is formed in the magnetic conversion unit, a fourth operation S140 of applying a second magnetic field to the magnetic track layer so that the magnetization direction of the magnetic conversion unit is antiparallel to the magnetization directions of the first magnetic fixed unit and the second magnetic fixed unit, a fifth operation S150 of applying a second current to the magnetic track layer so that a portion of the multi-domain penetrates into the first magnetic fixed unit, and a sixth operation S160 of applying a third magnetic field to the magnetic track layer so that the magnetization direction of the first magnetic fixed unit is antiparallel to the magnetization direction of the second magnetic fixed unit.

[0037] To provide a brief description, the operation method S10 of the magnetic memory device may include an operation of alternately applying a magnetic field pulse to the magnetic track layer three times and applying a current pulse to the magnetic track layer twice, so as to fix the magnetization direction of the first magnetic fixed unit and the magnetization direction of the second magnetic fixed unit to an antiparallel state relative to each other. However, the operation method S10 of the magnetic memory device is not limited thereto. In other embodiments, a person skilled in the art may easily understand the operation method S10 of the magnetic memory device based on the above description.

[0038] The following will refer to FIG. 4A to FIG. 4E Describing in detail the technical features of each of the first to sixth operations S110 to S160, FIG. 4A to FIG. 4E 1 is a plan view sequentially showing an operation method of a magnetic memory device according to an embodiment. Figure 4A , the first magnetic field H 1 It can be applied to all magnetic track layers 110 .

[0039] As described above, the magnetic track layer 110 may include a first magnetic fixed unit 111, a second magnetic fixed unit 112, and a magnetic conversion unit 113 disposed between the first magnetic fixed unit 111 and the second magnetic fixed unit 112 in the first horizontal direction X. In some embodiments, the first magnetic field H 1 It may be a magnetic field programmed so that all of the first magnetic fixing unit 111, the second magnetic fixing unit 112, and the magnetic conversion unit 113 have a perpendicular magnetization direction (eg, +Z). That is, in the first magnetic field H 1 In the embodiment, a perpendicular direction field greater than or equal to a threshold magnetic field may be applied to the magnetic track layer 110, and thus all magnetization directions of the magnetic domains may be equal to each other.

[0040] refer to Figure 4B , the first current J 0 is applied to all magnetic track layers 110. In some embodiments, the first current J 0 The magnitude of may be greater than the threshold current J for nucleation of multiple domains for forming the magnetic switching unit 113. n Based on the first current J 0 , multiple domains may be formed in the magnetic conversion unit 113, but multiple domains may not be formed in the first magnetic fixed unit 111 and the second magnetic fixed unit 112. This may be because the line width of the first magnetic fixed unit 111 and the line width of the second magnetic fixed unit 112 are greater than the line width of the magnetic conversion unit 113, so the current density in the first magnetic fixed unit 111 and the second magnetic fixed unit 112 is reduced, and thus the threshold current J of nucleation in the first magnetic fixed unit 111 and the second magnetic fixed unit 112 is not reached. n .

[0041] refer to Figure 4C , the second magnetic field H 2 is applied to all magnetic track layers 110. In some embodiments, the second magnetic field H 2 The size of can be set to have a magnetic field H greater than that used to enable the multi-domain to move in the magnetic domain. p and is smaller than the magnetic field H used to enable the multi-domain to enter another magnetic domain i Specifically, the second magnetic field H 2 The size of the magnetic field H may be set to have a value greater than the magnetic field H for enabling the multi-domain to move in the magnetic conversion unit 113. p However, it is also smaller than the magnetic field H for enabling the multi-domain to enter the first magnetic fixing unit 111 and the second magnetic fixing unit 112. i Therefore, the magnetization direction −Z of the magnetic switching unit 113 of the magnetic track layer 110 may be changed to an antiparallel state with respect to the magnetization directions +Z of the first magnetic fixed unit 111 and +Z of the second magnetic fixed unit 112 .

[0042] refer to Figure 4D , the second current J 1 is applied to all magnetic track layers 110. In some embodiments, the second current J 1 The size of can be set to be smaller than the threshold current J for nucleation of multi-domain formation n and is greater than the moving current J for enabling the multi-domain to move in the magnetic track layer 110 i In addition, the second current J 1The direction of the second current J may be set to flow in the opposite direction -X of the first horizontal direction X. Therefore, a portion of the multi-domain of the magnetic conversion unit 113 of the magnetic track layer 110 may penetrate into the first magnetic fixed unit 111 through the boundary surface between the first magnetic fixed unit 111 and the magnetic conversion unit 113. On the other hand, based on the second current J 1 direction, the multi-domains of the magnetic conversion unit 113 may not penetrate into the second magnetic fixed unit 112.

[0043] refer to Figure 4E , the third magnetic field H 3 is applied to all magnetic track layers 110. In some embodiments, the third magnetic field H 3 The size of can be set to have a magnetic field H greater than that used to enable the multi-domain to move in the magnetic domain. p and is smaller than the magnetic field H used to enable the multi-domain to enter another magnetic domain i That is, the third magnetic field H 3 The magnitude of the second magnetic field H 2 In addition, the third magnetic field H 3 The size of the magnetic field H may be set to have a value greater than the magnetic field H for enabling the multi-domain to move in the first magnetic fixing unit 111. p and is smaller than the magnetic field H for enabling the multi-domain to enter the second magnetic fixing unit 112 i Therefore, the magnetization direction −Z of the first magnetic fixed unit 111 of the magnetic track layer 110 may be changed to a state parallel to the magnetization direction −Z of the magnetic conversion unit 113 and antiparallel to the magnetization direction +Z of the second magnetic fixed unit 112 .

[0044] Therefore, based on the initialization process of the operating method of the magnetic memory device according to the embodiment, the magnetization direction -Z of the first magnetic fixed unit 111 and the magnetization direction +Z of the second magnetic fixed unit 112 can be fixed to an antiparallel state relative to each other. Therefore, the magnetic conversion unit 113 can change between stable magnetic states (ie, fixed states), and therefore, the operation of the stable magnetic junction structure for the read and write process can be performed.

[0045] Figure 5 and Figure 6 This is a table showing the magnetization direction based on the magnetic field and current field. Figure 5 , relative to the first magnetic field H 1 direction, the second magnetic field H 2 The direction of the second current J 1 The direction of φ shows the magnetization direction of the first magnetic fixing unit 111 and the second magnetic fixing unit 112 .

[0046] exist Figure 5 In the first scenario, in the first magnetic field H1 All free layers are changed to the upward direction +Z and the second magnetic field H 2 In the case of changing some magnetic domains to the upward direction -Z, when the second current J 1 When flowing in the left direction -X, the magnetization direction of the first magnetic fixing unit 111 may be the upper direction -Z and the magnetization direction of the second magnetic fixing unit 112 may be the upper direction +Z. 1 All free layers are changed to the upward direction +Z, and the second magnetic field H 2 In the case of changing some magnetic domains to the upward direction -Z, when the second current J 1 When the magnetic field H flows in the right direction +X, the magnetization direction of the first magnetic fixing unit 111 may be the upward direction +Z, and the magnetization direction of the second magnetic fixing unit 112 may be the upward direction -Z. 1 All free layers are changed to the upward direction -Z and the second magnetic field H 2 In the case of changing some magnetic domains to the upward direction +Z, when the second current J 1 When flowing in the left direction -X, the magnetization direction of the first magnetic fixing unit 111 may be the upward direction +Z and the magnetization direction of the second magnetic fixing unit 112 may be the upward direction -Z. Finally, in the fourth scenario, in the first magnetic field H 1 All free layers are changed to the upward direction -Z and the second magnetic field H 2 In the case of changing some magnetic domains to the upward direction +Z, when the second current J 1 When flowing in the right direction +X, the magnetization direction of the first magnetic fixing unit 111 may be the upper direction -Z and the magnetization direction of the second magnetic fixing unit 112 may be the upper direction +Z.

[0047] refer to Figure 6 , relative to the first magnetic field H 1 direction, the second magnetic field H 2 The direction of the second current J 1 The direction of the first magnetic fixed unit 111 and the second magnetic fixed unit 112 shows the magnetization direction. In the first scenario, the first magnetic field H1 changes all free layers to the right direction +X and the second magnetic field H 2 When some magnetic domains are changed to the left direction -X, the second current J 1 When the magnetic field H flows in the left direction -X, the magnetization direction of the first magnetic fixing unit 111 may be the left direction -X and the magnetization direction of the second magnetic fixing unit 112 may be the right direction +X. 1 All free layers are changed to the right direction +X and the second magnetic field H 2 When some magnetic domains are changed to the left direction -X, the second current J 1When the magnetic field H flows in the right direction +X, the magnetization direction of the first magnetic fixing unit 111 may be the right direction +X and the magnetization direction of the second magnetic fixing unit 112 may be the left direction -X. 1 All free layers are changed to the left direction -X and the second magnetic field H 2 In the case of changing some magnetic domains to the right direction +X, when the second current J 1 When the magnetic field H flows in the left direction -X, the magnetization direction of the first magnetic fixing unit 111 may be the right direction +X and the magnetization direction of the second magnetic fixing unit 112 may be the left direction -X. 1 All free layers are changed to the left direction -X and the second magnetic field H 2 In the case of changing some magnetic domains to the right direction +X, when the second current J 1 When flowing in the right direction +X, the magnetization direction of the first magnetic fixing unit 111 may be the left direction −X and the magnetization direction of the second magnetic fixing unit 112 may be the right direction +X.

[0048] 7A to 7C is an electron microscope photograph showing initialization of a magnetic memory device according to an embodiment. 7A to 7C The inventors have manufactured a magnetic track layer including a first magnetic fixed unit (left pad), a second magnetic fixed unit (right pad) and a magnetic switching unit (track), each of which has a fine size. Here, the contrast difference appearing in the electron microscope is shown with respect to the magnetization direction of the magnetic domain configuring the magnetic track layer to confirm whether the operation method of the magnetic memory device according to the embodiment is accurately performed.

[0049] That is, when the second magnetic field is applied to the magnetic track layer within the same range, the second current J 1 A shape in which the magnetization direction of the first magnetic fixing unit (left pad in the figure) and the magnetization direction of the second magnetic fixing unit (right pad in the figure) are changed differently is seen in the direction (right or left).

[0050] Figure 8 is a flow chart showing an algorithm of a magnetic memory device according to an embodiment. Figure 8 , stable initialization of the magnetic memory device can be performed by using an algorithm for the initialization process of the magnetic memory device. First, it can be checked whether a part of the magnetization direction of the first magnetic fixed unit changes after the operation (operation pulse) of applying the current. In this case, when a part of the magnetization direction of the first magnetic fixed unit changes, the next operation can be performed. On the other hand, when the magnetization direction of the first magnetic fixed unit does not change, fault AA can be determined.

[0051] Subsequently, after the operation of applying the magnetic field (opposite pulse), it can be determined whether all the magnetization directions of the first magnetic fixed unit have changed. In this case, when all the magnetization directions of the first magnetic fixed unit have changed, a success BB can be determined. On the other hand, when all the magnetization directions of the first magnetic fixed unit have not changed, a failure CC can be determined. The process of detecting an error of the operating method of the magnetic memory device according to the embodiment and correcting the error can be performed by using an algorithm for the initialization process.

[0052] Fig. 9 1 is a block diagram illustrating an electronic system 1200 including a magnetic memory device according to an embodiment. Fig. 9 , electronic system 1200 may require a memory device that stores a large amount of data for neural network device 1230 for advanced operations such as artificial intelligence (AI).

[0053] The electronic system 1200 may analyze input data to extract valid information based on the neural network device 1230 including the processing device, and may determine the situation of the electronic device equipped with the electronic system 1200 based on the extracted information or may control elements of the electronic device equipped with the electronic system 1200.

[0054] The human brain can transmit and process various signals through a neural network in which a plurality of neurons are connected to each other, and thus can learn and memorize a large amount of information. Various attempts are being made to develop a computing device or a processing device for replicating a biological neural network to efficiently process a large amount of information. Therefore, a nonvolatile memory device that stores various information in the form of data may be required, and in particular, a magnetic memory device may be required as a memory device that can store and quickly read high-capacity data.

[0055] The electronic system 1200 can be applied to robotic devices such as drones and advanced driver assistance systems (ADAS), smart televisions (TVs), smart phones, medical devices, mobile devices, image display devices, measuring devices, and Internet of Things (IoT) devices, and in addition, can be equipped in various electronic devices.

[0056] In addition to the neural network device 1230, the electronic system 1200 may include a processing unit 1210, a random access memory (RAM) 1220, a memory 1240, a sensor module 1250, and a communication module (Tx / Rx (receive / transmit) module) 1260. In addition, the electronic system 1200 may further include an input / output (I / O) module, a security module, and a power control device.

[0057] Some hardware elements of the electronic system 1200 may be configured as semiconductor chips. In the neural network device 1230 , the magnetic memory device according to the above-described embodiment may be implemented as an on-chip type, or the magnetic memory device according to the above-described embodiment may be included as an element of the neural network device 1230 .

[0058] The processing unit 1210 may control the overall operation of the electronic system 1200. The processing unit 1210 may be a central processing unit (CPU), and may include one processor core or may include multiple processor cores (multi-core). The processing unit 1210 may process or execute a program and / or data stored in the memory 1240, and may execute a program stored in the memory 1240 to control the functions of the neural network device 1230. In addition to the CPU, the processing unit 1210 may be implemented as a graphics processing unit (GPU) or an application processor (AP).

[0059] The RAM 1220 may temporarily store programs, data, or instructions. For example, based on a boot code or control of the processing unit 1210, each program and / or data stored in the memory 1240 may be temporarily stored in the RAM 1220. The RAM 1220 may be implemented as a memory device such as a dynamic RAM (DRAM) or a static RAM (SRAM).

[0060] The neural network device 1230 may perform arithmetic operations of the neural network based on the input data received thereby, and may generate an information signal based on the execution result. The neural network device 1230 may include the magnetic memory device according to the above-described embodiment as a memory device. In addition to the DNN, the neural network may also include a convolutional neural network (CNN), a recurrent neural network (RNN), a deep belief network, and a restricted Boltzmann machine, but is not limited thereto. The neural network device 1230 may correspond to a neural network dedicated hardware accelerator.

[0061] The information signal may include various recognition signals, such as a sound recognition signal, an object recognition signal, an image recognition signal, and a biometric information recognition signal. For example, the neural network device 1230 may receive frame data included in a video stream as input data, and may generate a recognition signal corresponding to an object included in an image represented by the frame data.

[0062] The neural network device 1230 may receive various input data based on the kind or function of the electronic device equipped with the electronic system 1200 , and may generate a recognition signal based on the input data.

[0063] The memory 1240 may be a storage device for storing data, and may store an operating system (OS), various programs, and various data. The memory 1240 may include a volatile memory or a nonvolatile memory. The memory 1240 may include a magnetic memory device according to the embodiment described above.

[0064] The sensor module 1250 may collect peripheral information about the electronic device equipped with the electronic system 1200. The sensor module 1250 may include various sensing devices, and further, may sense or receive signals (e.g., image signals, sound signals, magnetic signals, bio-signals, touch signals, etc.) from outside the electronic device, and may convert the sensed or received signals into data. In addition, the sensor module 1250 may provide the converted data as input data to the neural network device 1230.

[0065] The communication module 1260 may include various wired or wireless interfaces capable of communicating with external devices. The electronic system 1200 may also include a memory device for storing and executing processor and program data, a permanent storage device such as a disk drive, a communication port for communicating with external devices, and a user interface device such as a touch panel, keys, and buttons.

[0066] The operating method implemented as the above-mentioned algorithm or software module may be a computer-readable code or program instruction executable in a processor and may be stored in a computer-readable recording medium.

[0067] In the above, exemplary embodiments have been described in the drawings and the specification. The embodiments have been described by using the terms described herein, but this is only used to describe the inventive concept and is not used to limit the meaning or scope of the inventive concept defined in the appended claims. Therefore, it can be understood by those of ordinary skill in the art that various modifications and other equivalent embodiments can be implemented according to the inventive concept. Therefore, the spirit and scope of the inventive concept can be defined based on the spirit and scope of the appended claims.

[0068] While the inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the appended claims.

Claims

1. A method of operating a magnetic memory device, the method comprising: applying a first magnetic field to a magnetic track layer MTL including a first magnetic fixed unit, a second magnetic fixed unit, and a magnetic switching unit MTU extending in a first direction between the first magnetic fixed unit and the second magnetic fixed unit, so that the first magnetic fixed unit, the second magnetic fixed unit, and the MTU have magnetization directions parallel to each other; applying a first current to the MTL so as to establish multiple domains within the MTU; applying a second magnetic field to the MTL so that the magnetization direction of the MTU is switched to become antiparallel to the magnetization directions of the first magnetic fixing unit and the second magnetic fixing unit; applying a second current to the MTL so that a portion of the multi-domain penetrates into the first magnetic fixed unit; as well as A third magnetic field is applied to the MTL so that the magnetization direction of the first magnetic fixed unit is switched to become antiparallel to the magnetization direction of the second magnetic fixed unit.

2. The method according to claim 1, wherein: The MTU has a linear shape extending longitudinally in the first direction, and wherein the first and second magnetic fixing units contact first and second opposite ends of the MTU, respectively.

3. The method according to claim 2, in, The first magnetic fixing unit and the second magnetic fixing unit have a trapezoidal shape and are configured as mirror images of each other with respect to the MTU; The angle between a virtual line extending along the side wall of the end of the MTU and the inclined side of the second magnetic fixing unit is greater than 0 degree and less than 90 degrees.

4. The method according to claim 1, wherein: The magnitude of the second magnetic field is larger than the magnetic field for enabling the multi-domains to move within the MTU, but smaller than the magnetic field for enabling the multi-domains to enter the first magnetic fixed unit and the second magnetic fixed unit.

5. The method according to claim 4, wherein: The third magnetic field has a magnitude greater than a magnetic field for enabling the multi-domain to move within the first magnetic fixing unit, but smaller than a magnetic field for enabling the multi-domain to enter the second magnetic fixing unit.

6. The method according to claim 5, wherein: The first magnetic field is configured such that all of the first magnetic fixed unit, the second magnetic fixed unit, and the MTU have a second magnetization direction orthogonal to the first direction.

7. The method according to claim 1, wherein: The magnitude of the first current is greater than a threshold current for forming multiple domains within the MTU.

8. The method according to claim 7, wherein: The magnitude of the second current is smaller than the threshold current but larger than a current for enabling the multi-domain to move within the MTL. 9 . The method of claim 1 , further comprising placing a read unit on the MTU to form a magnetic tunnel junction structure.

10. The method according to claim 9, wherein: The read unit is a pinned layer of the magnetic tunnel junction structure; wherein the MTL is a free layer of the magnetic tunnel junction structure; and wherein the read unit is configured to read a magnetization direction of the MTU.

11. A method for operating a magnetic memory device, for fixing the magnetization direction of a first magnetic pad and the magnetization direction of a second magnetic pad to be in an antiparallel state relative to each other, the method comprising: preparing a magnetic tunnel junction structure, the magnetic tunnel junction structure comprising a free layer, a tunnel barrier layer and a pinned layer, wherein in the free layer, the magnetic conversion unit is arranged between the first magnetic pad and the second magnetic pad in a horizontal direction, and the tunnel barrier layer and the pinned layer are respectively arranged on the magnetic conversion unit in a vertical direction; Applying a first magnetic field to the free layer so that the first magnetic pad, the second magnetic pad, and the magnetic conversion unit have magnetization directions parallel to each other; applying a first current to the free layer so that multiple domains are formed in the magnetic switching unit; Applying a second magnetic field to the free layer so that the magnetization direction of the magnetic conversion unit is antiparallel to the magnetization directions of the first magnetic pad and the second magnetic pad; applying a second current to the free layer so that a portion of the multi-domain penetrates into the first magnetic pad; as well as A third magnetic field is applied to the free layer so that a magnetization direction of the first magnetic pad is antiparallel to a magnetization direction of the second magnetic pad.

12. The method according to claim 11, wherein: The free layer is a magnetic track layer in which the first magnetic pad, the magnetic switching unit, and the second magnetic pad have a bow-tie shape. 13 . The method according to claim 11 , further comprising fixing a magnetization direction of the first magnetic pad and a magnetization direction of the second magnetic pad to an antiparallel state relative to each other by using the magnetic tunnel junction structure, and reading a magnetization direction of the magnetic conversion unit.

14. The method according to claim 13, wherein: Each of the first magnetic pad and the second magnetic pad is electrically connected to a conductive layer.

15. The method according to claim 11, in, The first magnetic field is a magnetic field programmed to make all the free layers have the same magnetization direction; wherein the second magnetic field is larger than a magnetic field for enabling the multi-domain to move in the magnetic conversion unit, and smaller than a magnetic field for enabling the multi-domain to enter the first magnetic pad and the second magnetic pad; and The third magnetic field is greater than a magnetic field for enabling the multi-domains to move in the first magnetic pad, and is smaller than a magnetic field for enabling the multi-domains to enter the second magnetic pad.

16. A method of operating a magnetic memory device, the method comprising: In a magnetic tunnel junction structure including a stacked structure of a free layer, a tunnel barrier layer and a pinned layer, the free layer includes a first magnetic pad, a second magnetic pad and a magnetic conversion unit arranged between the first magnetic pad and the second magnetic pad in a horizontal direction; A magnetic field pulse is applied to the free layer three times, and a current pulse is applied to the free layer twice to fix the magnetization direction of the first magnetic pad and the magnetization direction of the second magnetic pad to an antiparallel state with respect to each other.

17. The method according to claim 16, wherein: The free layer is a magnetic track layer in which the first magnetic pad, the magnetic switching unit, and the second magnetic pad have a bow-tie shape.

18. The method according to claim 16, in, The current pulse applied twice includes a first current pulse and a second current pulse; wherein the first current pulse is greater than a threshold current for forming multiple domains in the magnetic switching unit; and The second current pulse is smaller than the threshold current and larger than a current pulse for enabling the multi-domain to move in the free layer.

19. The method according to claim 18, in, The magnetic field pulses applied three times include a first magnetic field pulse, a second magnetic field pulse and a third magnetic field pulse; wherein the first magnetic field pulse is programmed so that the first magnetic pad, the second magnetic pad, and all of the magnetic conversion units have the same magnetization direction; wherein the second magnetic field pulse is larger than a magnetic field for enabling the multi-domain to move in the magnetic conversion unit, and smaller than a magnetic field for enabling the multi-domain to enter the first magnetic pad and the second magnetic pad; and The third magnetic field pulse is the same as the second magnetic field pulse.

20. The method according to claim 19, wherein: The first magnetic field pulse, the first current pulse, the second magnetic field pulse, the second current pulse, and the third magnetic field pulse are sequentially applied to the free layer.

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