Magnetic tunnel junction device and memory device including same

Abstract

A magnetic tunnel junction device and a memory device including the magnetic tunnel junction device are provided. The magnetic tunnel junction device includes a seed layer, a pinned layer on the seed layer, a free layer facing the pinned layer, and a tunnel barrier layer between the pinned layer and the free layer, where the seed layer includes a first seed layer and a second seed layer between the first seed layer and the pinned layer, and one of the first seed layer and the second seed layer includes rhenium (Re), and the other of the first seed layer and the second seed layer includes ruthenium (Ru).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on and claims the benefit of priority from Korean Patent Application No. 10-2023-0136216 filed in the Korean Intellectual Property Office on October 12, 2023, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] The present disclosure relates to a magnetic (magnetic) tunnel junction device and a storage device (memory device) including the magnetic tunnel junction device. Background Art

[0004] Magnetic storage devices such as magnetic random access memory (MRAM) store data by using the change in the resistance of a magnetic tunnel junction device. The resistance of a magnetic tunnel junction device varies with the magnetization direction of the free layer. For example, when the magnetization direction of the free layer is the same as that of the pinned layer, the magnetic tunnel junction device may have a low resistance, and when the magnetization direction of the free layer is opposite to that of the pinned layer, the magnetic tunnel junction device may have a high resistance. When this characteristic is used in a storage device, for example, a magnetic tunnel junction device with a low resistance may correspond to data "0", and a magnetic tunnel junction device with a high resistance may correspond to data "1".

[0005] In the process of manufacturing a memory device including such a magnetic tunnel junction device, it is advantageous to prevent or minimize degradation of the magnetic tunnel junction device due to high temperature heat treatment. Summary of the invention

[0006] Some example embodiments of the present disclosure provide magnetic tunnel junction devices that are capable of maintaining performance even during relatively high temperature thermal treatment processes.

[0007] Some example embodiments of the present invention provide a memory device including the magnetic tunnel junction device described above.

[0008] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented example embodiments of the disclosure.

[0009] According to an example embodiment, a magnetic tunnel junction device includes a seed layer, a pinned layer on the seed layer, a free layer facing the pinned layer, and a tunnel barrier layer between the pinned layer and the free layer, wherein the seed layer includes a first seed layer and a second seed layer, and the second seed layer is between the first seed layer and the pinned layer, and one of the first seed layer and the second seed layer includes rhenium (Re), and the other of the first seed layer and the second seed layer includes ruthenium (Ru).

[0010] The total thickness of the seed layer may be 1 nm or more and 10 nm or less.

[0011] The first seed layer may include rhenium (Re), and the second seed layer may include ruthenium (Ru).

[0012] The thickness of the first seed layer is 50% or more of the total thickness of the seed layer.

[0013] The first seed layer includes ruthenium (Ru), and the second seed layer may include rhenium (Re).

[0014] The thickness of the second seed layer may be 50% or more of the total thickness of the seed layer.

[0015] The seed layer may further include a third seed layer between the second seed layer and the pinned layer.

[0016] The first seed layer may include rhenium (Re), the second seed layer includes ruthenium (Ru), and the third seed layer includes rhenium (Re).

[0017] A sum of a thickness of the first seed layer and a thickness of the third seed layer may be 50% or more of a total thickness of the seed layer.

[0018] The first seed layer may include ruthenium (Ru), the second seed layer may include rhenium (Re), and the third seed layer may include ruthenium (Ru).

[0019] The thickness of the second seed layer may be 50% or more of the total thickness of the seed layer.

[0020] The pinned layer may include a first ferromagnetic layer adjacent to the seed layer, a second ferromagnetic layer adjacent to the tunnel barrier layer, and a synthetic antiferromagnetic (SAF) coupling layer disposed between the first ferromagnetic layer and the second ferromagnetic layer, and the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer may be opposite to each other.

[0021] The SAF coupling layer may include a conductive metal.

[0022] The magnetic tunnel junction device may further include a polarization enhanced layer between the pinned layer and the tunnel barrier layer and including a ferromagnetic material.

[0023] According to an example embodiment, a magnetic tunnel junction device includes a seed layer, a pinned layer on the seed layer, a free layer facing the pinned layer, and a tunnel barrier layer between the pinned layer and the free layer, and wherein the seed layer is a single layer including a rhenium (Re) alloy having a hexagonal close-packed (HCP) structure.

[0024] The ruthenium alloy may include an alloy of rhenium (Re) and at least one metal of ruthenium (Ru), platinum (Pt), gold (Au), iridium (Ir), or cobalt (Co).

[0025] A ratio of rhenium (Re) in the seed layer may be 50 atomic % or more, and a ratio of the at least one metal other than rhenium (Re) may be 50 atomic % or less based on the total number of atoms in the seed layer.

[0026] According to an example embodiment, a storage device includes a plurality of storage cells, each of the plurality of storage cells includes a magnetic tunnel junction device and a switching device connected to the magnetic tunnel junction device, wherein the magnetic tunnel junction device includes a seed layer, a pinned layer on the seed layer, a free layer facing the pinned layer, and a tunnel barrier layer between the pinned layer and the free layer, wherein the seed layer includes a first seed layer and a second seed layer between the first seed layer and the pinned layer, and one of the first seed layer and the second seed layer includes rhenium (Re), and the other of the first seed layer and the second seed layer includes ruthenium (Ru).

[0027] The memory device may further include a passivation layer between the plurality of memory cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other aspects, features and advantages of some example embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device according to an example embodiment;

[0030] Figure 2A The surface of the seed layer including only ruthenium after heat treatment is shown. Figure 2B The surface of the seed layer after heat treatment only includes rhenium. Figure 2C shows the surface of the pinned layer disposed on the seed layer comprising only ruthenium after heat treatment, and Figure 2D showing a surface of a pinned layer disposed on a seed layer of a double-layer structure including rhenium / ruthenium after heat treatment;

[0031] Figure 3A is a cross-sectional view of a seed layer including only ruthenium and a pinned layer disposed thereon, Figure 3B is an enlarged cross-sectional view of a portion of a seed layer including only ruthenium, and Figure 3C A diffraction image showing a seed layer comprising only ruthenium;

[0032] Figure 4Ais a cross-sectional view of a seed layer including a double-layer structure of rhenium / ruthenium and a pinned layer disposed thereon, Figure 4B is an enlarged cross-sectional view of a portion of the rhenium seed layer, Figure 4C is an enlarged cross-sectional view of a portion of a ruthenium seed layer, Figure 4D shows the diffraction image of the rhenium seed layer, and Figure 4E Diffraction image showing the ruthenium seed layer;

[0033] Figure 5A and 5B A comparison of the resistance-area product (RA) and tunnel magnetoresistance ratio (TMR) of magnetic tunnel junction devices according to various seed layer configurations is shown;

[0034] Figure 6 is a graph for comparing a Kerr rotation angle with respect to an external magnetic field in a pinned layer disposed on a seed layer including only ruthenium with a Kerr rotation angle with respect to an external magnetic field in a pinned layer disposed on a seed layer including only rhenium;

[0035] Figure 7 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device according to another example embodiment;

[0036] Figure 8 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device according to another example embodiment;

[0037] Fig. 9 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device according to another example embodiment;

[0038] Fig.10 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device according to another example embodiment;

[0039] Fig.11 schematically shows a structure of a memory cell including a magnetic tunnel junction device according to an example embodiment;

[0040] Fig.12 To show Fig.11 A perspective view of an arrangement structure of a magnetic tunnel junction device and a switch device in a memory cell shown in FIG.

[0041] Fig.13 A circuit diagram schematically showing a configuration of a memory device including a plurality of memory cells;

[0042] Fig.14 Schematically displayed Fig.13 A cross-sectional structure of a plurality of memory cells of a memory device shown in; and

[0043] Fig.15The conceptual diagram schematically illustrates a device architecture applicable to an electronic device according to an example embodiment. DETAILED DESCRIPTION

[0044] Some example embodiments will now be described in detail, examples of which are shown in the accompanying drawings, wherein the same reference numerals always refer to the same elements. In this regard, the present example embodiments may have different forms and should not be construed as being limited to the description set forth herein. Therefore, the present example embodiments are described below only by reference to the accompanying drawings to illustrate aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. When before or after a list of elements, a statement such as "at least one (kind) of ... " or "at least one (kind) of ... " modifies the entire list of elements, and does not modify the individual elements of the list.

[0045] Hereinafter, a magnetic tunnel junction device and a memory device including the magnetic tunnel junction device will be described in detail with reference to the accompanying drawings. The same reference numerals refer to the same elements throughout, and in the accompanying drawings, the size of the elements may be exaggerated for clarity and convenience of description. The example embodiments described below are merely examples, and various modifications may be possible from the disclosed example embodiments.

[0046] In the layer structure described below, the expression "over..." or "on..." may include not only "directly on..." in a contacting manner, but also "on..." in a non-contacting manner. Expressions used in the singular encompass expressions in the plural unless they have obviously different meanings in the context. It will be further understood that the term "comprising" used herein indicates the presence of stated features or elements, but does not exclude the presence or addition of one or more other features or elements.

[0047] The use of "said" and other indicators similar thereto may correspond to both singular and plural forms. Unless the order of operations of the method according to the present disclosure is explicitly mentioned or otherwise described, the operations may be performed in an appropriate order. The present disclosure is not limited to the order in which the operations are mentioned.

[0048] Terms such as “unit” or “module” used in the example embodiments mean a unit for processing at least one function or operation, and may be implemented in hardware or software, or in a combination of hardware and software.

[0049] The connecting lines or connectors shown in the various figures presented are intended to represent functional relationships and / or physical or logical couplings between the various elements. It should be noted that many alternative or additional functional relationships, physical connections or logical connections may exist in a practical device.

[0050] Although the terms "same," "equal," or "equivalent" are used in the description of example embodiments, it should be understood that some imprecision may exist. Thus, when an element is referred to as being the same as another element, it should be understood that the element or value is the same as the other element within a desired manufacturing or operating tolerance range (e.g., ±10%).

[0051] When the terms "about," "substantially," or "approximately" are used in conjunction with a numerical value in this application, it is intended that the associated numerical value include a manufacturing or operating tolerance (e.g., ±10%) around the stated numerical value. In addition, when the words "about," "substantially," or "approximately" are used in conjunction with a geometric shape, it is intended that the precision of the geometric shape is not required, but that tolerances for the shape are within the scope of the present disclosure. In addition, regardless of whether a numerical value or shape is modified as "about" or "substantially," it will be understood that these values ​​and shapes should be interpreted as including manufacturing or operating tolerances (e.g., ±10%) around the stated numerical value or shape.

[0052] The use of any and all examples, or language provided herein, is intended merely to better illuminate the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed.

[0053] Figure 1 FIG. 1 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device 100 according to an example embodiment. Figure 1 , the magnetic tunnel junction device 100 may include a seed layer 102, a pinned layer 103 disposed on the seed layer 102, a tunnel barrier layer 104 disposed on the pinned layer 103, and a free layer 105 disposed on the tunnel barrier layer 104. The expression "disposed on..." is only for the convenience of description and does not necessarily mean a vertical relationship. In other words, the pinned layer 103 and the free layer 105 may be disposed to face each other, and the tunnel barrier layer 104 may be disposed between the pinned layer 103 and the free layer 105. The magnetic tunnel junction device 100 according to the example embodiment may further include a capping oxide layer 106 disposed on the free layer 105 and a capping metal layer 107 disposed on the capping oxide layer 106.

[0054] The pinned layer 103 and the free layer 105 may include a ferromagnetic metal material having magnetism. For example, the pinned layer 103 and the free layer 105 may include at least one of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), an alloy including Fe, an alloy including Co, an alloy including Ni, an alloy including Mn, an alloy including Ru, or a Heusler alloy. The pinned layer 103 may have a pinned magnetization direction. The free layer 105 may have a variable magnetization direction. When the magnetization directions of the pinned layer 103 and the free layer 105 are the same, the magnetic tunnel junction device 100 may have a low resistance, and when the magnetization directions thereof are opposite to each other, the magnetic tunnel junction device 100 may have a high resistance. This phenomenon is called tunnel magnetoresistance (tunneling magnetoresistance) (TMR). By applying the TMR phenomenon, the magnetic tunnel junction device 100 can be used in a storage device.

[0055] According to example embodiments, the pinned layer 103 and the free layer 105 may have high perpendicular magnetic anisotropy (PMA), specifically, interface perpendicular magnetic anisotropy (IPMA). In other words, the PMA energy of each of the pinned layer 103 and the free layer 105 may exceed the out-of-plane demagnetization energy. In this case, the magnetic moment of each of the pinned layer 103 and the free layer 105 may be stabilized in a direction perpendicular to the layer direction. The magnetic tunnel junction device 100 may be applied to a spin transfer torque magnetic RAM (STT-MRAM) or a spin orbit torque (SOT)-MRAM.

[0056] In order to improve the operating speed of the storage device using the magnetic tunnel junction device 100, the free layer 105 may have a low saturation magnetization (Ms). In order to reduce the saturation magnetization Ms of the free layer 105, the free layer 105 may be further doped with a non-magnetic metal element. For example, the free layer (105) may be doped with at least one non-magnetic metal of calcium (Ca), scandium (Sc), yttrium (Y), magnesium (Mg), strontium (Sr), barium (Ba), zirconium (Zr), beryllium (Be), titanium (Ti), hafnium (Hf), vanadium (V), zinc (Zn), niobium (Nb), manganese (Mn), aluminum (Al), chromium (Cr), lithium (Li), cadmium (Cd), lead (Pb), indium (In), gallium (Ga), or tantalum (Ta). The non-magnetic metal doped into the free layer 105 may have an oxygen affinity higher than the oxygen affinity (affinity) of the ferromagnetic metal material of the free layer 105.

[0057] In addition, when necessary, the free layer 105 may have a multilayer structure including two or more layers: a layer including only a ferromagnetic metal material and a layer doped with a non-magnetic metal. The material and structure of the free layer 105 can reduce or prevent the diffusion of oxygen or metal elements at the interface with the tunnel barrier layer 104.

[0058] The tunnel barrier layer 104 may be used to provide a magnetic tunnel junction between the pinned layer 103 and the free layer 105. The tunnel barrier layer 104 may include a crystalline metal oxide. For example, the tunnel barrier layer 104 may include MgO, MgAl 2 O 4 or MgTiO x , where 1≤x≤4.

[0059] Meanwhile, the magnetic tunnel junction device 100 may further include a lower electrode 101. The lower electrode 101 may include a conductive material to apply current to the magnetic tunnel junction device 100. The lower electrode 101 may include a low-resistance metal or a metal nitride. For example, the lower electrode 101 may include TiN or TaN. The lower electrode 101 may be a part of the magnetic tunnel junction device 100, but may also be a part of a memory device including the magnetic tunnel junction device 100.

[0060] TiN or TaN used as the lower electrode 101 has a body-centered cubic lattice (BCC) structure. On the other hand, the crystals of the ferromagnetic metal material used in the pinned layer 103 disposed on the lower electrode 101 mainly have a hexagonal close-packed (HCP) structure with a (0001) crystal orientation. Therefore, when the pinned layer 103 is directly formed on the lower electrode 101, the crystal quality of the pinned layer 103 may deteriorate. Therefore, the seed layer 102 may be disposed between the lower electrode 101 and the pinned layer 103 to prevent or minimize the deterioration of the crystal quality of the pinned layer 103. In other words, the seed layer 102 may be first formed on the lower electrode 101, and the pinned layer 103 may be formed on the seed layer 102.

[0061] The seed layer 102 may include a material on which crystals of an HCP structure can grow. In addition, during high-temperature heat treatment in a manufacturing process of a storage device including the magnetic tunnel junction device 100, the seed layer 102 may have a material and structure that can prevent or minimize the deterioration of the characteristics of the pinned layer 103 and the deterioration of the texture of the seed layer 102 due to intermixing between the seed layer 102 and the pinned layer 103, etc. To this end, the seed layer 102 may include rhenium (Re). Rhenium (Re) has a very high melting point of about 3186°C and also has an HCP crystal structure. Therefore, even when annealed at a temperature of about 400°C for about 5 hours, rhenium (Re) can well maintain the HCP structure.

[0062] Figure 2A shows the surface of a seed layer comprising only ruthenium (Ru) after heat treatment, Figure 2B shows the surface of the seed layer comprising only rhenium (Re) after heat treatment, Figure 2C shows the surface of a pinned layer disposed on a seed layer comprising only ruthenium (Ru) after thermal treatment, and Figure 2D The surface of the pinned layer disposed on the seed layer including the double-layer structure of rhenium (Re) / ruthenium (Ru) after heat treatment is shown. Figures 2A to 2D In the process, the heat treatment was performed at 400°C for 5 hours. Figure 2C and 2D In the embodiment, CoPtCr is used as the pinned layer.

[0063] Reference Figure 2A and 2B , it can be seen that the surface roughness of the seed layer including only rhenium (Re) after the heat treatment is lower than the surface roughness of the seed layer including only ruthenium (Ru) after the heat treatment. For example, the root mean square (RMS) surface roughness of the seed layer including only ruthenium (Ru) after the heat treatment is about 0.324 nm, and the RMS surface roughness of the seed layer including only rhenium (Re) after the heat treatment is about 0.169 nm. In addition, referring to Figure 2C and Figure 2D , it can be seen that the surface roughness of the pinned layer disposed on the seed layer of the double-layer structure including rhenium (Re) / ruthenium (Ru) after the heat treatment is lower than the surface roughness of the pinned layer disposed on the seed layer including only ruthenium (Ru) after the heat treatment. For example, the RMS surface roughness of the pinned layer disposed on the seed layer including only ruthenium (Ru) after the heat treatment is 1.04 nm, and the RMS surface roughness of the pinned layer disposed on the seed layer of the double-layer structure including rhenium (Re) / ruthenium (Ru) after the heat treatment is 0.763 nm.

[0064] Figure 3A is a cross-sectional view of a seed layer including only ruthenium (Ru) and a pinned layer disposed thereon, Figure 3B is an enlarged cross-sectional view of a portion of a seed layer including only ruthenium (Ru), and Figure 3C The diffraction image of the seed layer including only ruthenium (Ru) is shown. In addition, Figure 4A is a cross-sectional view of a seed layer including a double-layer structure of rhenium (Re) / ruthenium (Ru) and a pinned layer disposed thereon, Figure 4B is an enlarged cross-sectional view of a portion of a rhenium (Re) seed layer, Figure 4C is an enlarged cross-sectional view of a portion of a ruthenium (Ru) seed layer, Figure 4D Displays the diffraction image of the rhenium (Re) seed layer, and Figure 4E Shows the diffraction pattern of a ruthenium (Ru) seed layer. Figures 3A to 3C as well as Figures 4A to 4E Both show the crystallization state of the seed layer and the pinned layer after heat treatment at 400°C for 5 hours. Figure 4E In the diffraction image of , the diffraction image of ruthenium (Ru) and the diffraction image of rhenium (Re) are mixed.

[0065] In the Figure 3A and 3B The cross-sectional image and Figure 4A , Figure 4B and Figure 4C When comparing the cross-sectional images of the 2D-type quartz crystals, it can be seen that the crystal quality of the seed layer and the pinned layer disposed thereon, which are composed of a double-layer structure of rhenium (Re) / ruthenium (Ru), has been further improved. Figure 3C The diffraction image of Figure 4D and 4E When comparing the diffraction images of , it can be seen that the double-layer structure including rhenium (Re) / ruthenium (Ru) and the pinned layer disposed thereon maintain better crystal quality even after heat treatment at a temperature of 400° C. for 5 hours.

[0066] Figure 5A and 5B A comparison of the resistance-area product (RA) and tunnel magnetoresistance ratio (TMR) of magnetic tunnel junction devices according to various seed layer configurations is shown. For example, Figure 5A is a table showing RA and TMR of magnetic tunnel junction devices according to various seed layer configurations, and Figure 5B To display Figure 5A Figure 2 shows the TMR of a magnetic tunnel junction device according to various seed layer configurations. Figure 5A and 5B In the invention, the magnetic tunnel junction device has Figure 1 The same structure as shown in , except for the configuration of the seed layer. CoPtCr is used for the pinned layer.

[0067] Reference Figure 5A, the RA value of a magnetic tunnel junction device including a seed layer including only ruthenium (Ru) is about 8.3, and its TMR value is about 162.7%. The RA value of a magnetic tunnel junction device including a seed layer including only rhenium (Re) is about 9.4, and its TMR value is about 180.2%. The RA value of a magnetic tunnel junction device including a seed layer of a double-layer structure of rhenium (Re) / ruthenium (Ru) is about 9.0, and its TMR value is about 190.0%. In a double-layer structure including rhenium (Re) / ruthenium (Ru), rhenium (Re) may be provided on the lower electrode 101 and ruthenium (Ru) may be provided on rhenium (Re). In addition, the RA value of a magnetic tunnel junction device including a seed layer of a double-layer structure including ruthenium (Ru) / rhenium (Re) is about 8.2, and its TMR value is about 185.2%. In the double-layer structure including ruthenium (Ru) / rhenium (Re), ruthenium (Ru) may be provided on the lower electrode 101 and rhenium (Re) may be provided on ruthenium (Ru). Therefore, the RA value of the magnetic tunnel junction device including the seed layer including only rhenium (Re) is the largest, and the RA value of the magnetic tunnel junction device including the seed layer of the double-layer structure including rhenium (Re) / ruthenium (Ru) is the second largest. The RA value of the magnetic tunnel junction device including the seed layer including only ruthenium (Ru) and the RA value of the magnetic tunnel junction device including the seed layer formed by the double-layer structure including ruthenium (Ru) / rhenium (Re) may be similar.

[0068] At the same time, refer to Figure 5A and 5B , the TMR value of the magnetic tunnel junction device including a seed layer of a double-layer structure including rhenium (Re) / ruthenium (Ru) and the TMR value of the magnetic tunnel junction device including a seed layer of a double-layer structure including ruthenium (Ru) / rhenium (Re) are further greater than the TMR value of the magnetic tunnel junction device including a seed layer including only ruthenium (Ru) and the TMR value of the magnetic tunnel junction device including a seed layer including only rhenium (Re).

[0069] Figure 6 1 is a graph for comparing the Kerr rotation angle with respect to an external magnetic field in a pinned layer disposed on a seed layer including only ruthenium (Ru) and the Kerr rotation angle with respect to an external magnetic field in a pinned layer disposed on a seed layer including only rhenium (Re). Figure 6 In the embodiment, the pinned layer may be a synthetic antiferromagnet (SAF) comprising two layers of CoPt. Figure 6, in a pinned layer disposed on a seed layer including only ruthenium (Ru), deterioration of the pinned layer begins at about 6 kOe. When the intensity of the external magnetic field exceeds about 6 kOe, the pinned layer loses the characteristics of a diamagnetic material. On the other hand, the pinned layer disposed on a seed layer including only rhenium (Re) maintains the characteristics of a diamagnetic material until about 10 kOe. Therefore, the pinned layer disposed on a seed layer including only rhenium (Re) may have a higher exchange coupling field (Hex) and higher stability than the pinned layer disposed on a seed layer including only ruthenium (Ru).

[0070] Considering the above Figures 2A to 6 According to the experimental results, when the seed layer 102 includes rhenium (Re), the surface roughness, crystal quality and / or Hex characteristics of the pinned layer 103 can be improved. In addition, it can be seen that the seed layer 102 having a double-layer structure including rhenium (Re) can further improve the TMR characteristics of the magnetic tunnel junction device 100 compared to the seed layer including only rhenium (Re). In other words, when rhenium (Re) and ruthenium (Ru) are used together as the seed layer 102 in a double-layer structure, the magnetic tunnel junction device 100 can show better characteristics than when only rhenium (Re) is used alone. In view of this, the seed layer 102 according to some example embodiments may have a double-layer structure including rhenium (Re).

[0071] For example, Figure 1 As shown in , the seed layer 102 may include a first seed layer 102a disposed on the lower electrode 101 and a second seed layer 102b disposed on the first seed layer 102a. The pinned layer 103 may be disposed on the second seed layer 102b. In other words, the second seed layer 102b may be disposed between the first seed layer 102a and the pinned layer 103. In addition, the pinned layer 103 may directly contact the second seed layer 102b. According to example embodiments, one of the first seed layer 102a and the second seed layer 102b may include rhenium (Re), and the other may include ruthenium (Ru). For example, the first seed layer 102a may include rhenium (Re), and the second seed layer 102b may include ruthenium (Ru). The first seed layer 102a may include ruthenium (Ru), and the second seed layer 102b may include rhenium (Re).

[0072] The total thickness of the seed layer 102 may be, for example, about 1 nm or more and about 10 nm or less. The total thickness of the seed layer 102 may be defined as the distance between the lower surface of the first seed layer 102a contacting the lower electrode 101 and the upper surface of the second seed layer 102b contacting the pinned layer 103. In order to fully obtain the effect of rhenium (Re), the thickness of one of the first seed layer 102a and the second seed layer 102b including rhenium (Re) may be 50% or more of the total thickness of the seed layer 102. For example, when the total thickness of the seed layer 102 is 10 nm, the first seed layer 102a includes rhenium (Re), and the second seed layer 102b includes ruthenium (Ru), the thickness of the first seed layer 102a may be 5 nm or more, which is 50% or more of the total thickness of the seed layer 102. When the total thickness of the seed layer 102 is 10 nm, the first seed layer 102a includes ruthenium (Ru), and the second seed layer 102b includes rhenium (Re), the thickness of the second seed layer 102b may be 5 nm or more, which is 50% or more of the total thickness of the seed layer 102.

[0073] Figure 7 FIG. 1 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device 100 a according to another example embodiment. Figure 7 , the seed layer 102' of the magnetic tunnel junction device 100a according to another example embodiment may have a three-layer structure including rhenium (Re). For example, the seed layer 102' may include a first seed layer 102a disposed on the lower electrode 101, a second seed layer 102b disposed on the first seed layer 102a, and a third seed layer 102c disposed on the second seed layer 102b. The pinned layer 103 may be disposed on the third seed layer 102c. In other words, the second seed layer 102b may be disposed between the first seed layer 102a and the third seed layer 102c, and the third seed layer 102c may be disposed between the second seed layer 102b and the pinned layer 103. In addition, the pinned layer 103 may directly contact the third seed layer 102c.

[0074] The first seed layer 102a, the second seed layer 102b and the third seed layer 102c may alternately include rhenium (Re) and ruthenium (Ru). For example, the first seed layer 102a may include rhenium (Re), the second seed layer 102b may include ruthenium (Ru), and the third seed layer 102c may include rhenium (Re). In other words, the seed layer 102' may have a Re / Ru / Re structure. Alternatively, the first seed layer 102a may include ruthenium (Ru), the second seed layer 102b may include rhenium (Re), and the third seed layer 102c may include ruthenium (Ru). In other words, the seed layer 102' may have a Ru / Re / Ru structure.

[0075] Even when the seed layer 102' has a three-layer structure, the sum of the thicknesses of the layers including rhenium (Re) may be 50% or more of the total thickness of the seed layer 102'. For example, when the seed layer 102' has a Re / Ru / Re structure, the sum of the thickness of the first seed layer 102a and the thickness of the third seed layer 102c may be 50% or more of the total thickness of the seed layer 102'. When the seed layer 102' has a Ru / Re / Ru structure, the thickness of the second seed layer 102b may be 50% or more of the total thickness of the seed layer 102'. The total thickness of the seed layer 102' may be defined as the distance between the lower surface of the first seed layer 102a contacting the lower electrode 101 and the upper surface of the third seed layer 102c contacting the pinned layer 103.

[0076] Figure 7 The seed layer 102' is shown as a three-layer structure, but the disclosure is not limited thereto. For example, the seed layer 102' may have a multilayer structure of four or more layers. In this case, a layer including rhenium (Re) and a layer including ruthenium (Ru) may be alternately arranged in the seed layer 102'.

[0077] Except for the seed layer 102' Figure 7 The configuration of the magnetic tunnel junction device 100a shown in FIG. Figure 1 The configuration of the magnetic tunnel junction device 100 shown in FIG. 1 is the same as that of the magnetic tunnel junction device 100 shown in FIG. Figure 7 Detailed description of the magnetic tunnel junction device 100a shown in FIG.

[0078] Figure 8 FIG. 1 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device 100 b according to another example embodiment. Figure 8 , the pinned layer 103' of the magnetic tunnel junction device 100b may include SAF. The pinned layer 103' may include, for example, a first ferromagnetic layer 103a adjacent to the seed layer 102, a second ferromagnetic layer 103c adjacent to the tunnel barrier layer 104, and a SAF coupling layer 103b arranged between the first ferromagnetic layer 103a and the second ferromagnetic layer 103c. In this case, the first ferromagnetic layer 103a, the SAF coupling layer 103b, the second ferromagnetic layer 103c, the tunnel barrier layer 104, and the free layer 105 may be sequentially formed on the upper surface of the seed layer 102.

[0079] The SAF coupling layer 103b may include a conductive metal. For example, the SAF coupling layer 103b may include at least one of iridium (Ir), ruthenium (Ru), aluminum (Al), copper (Cu), silver (Ag), or an alloy thereof. The first ferromagnetic layer 103a and the second ferromagnetic layer 103c may each have a single-layer structure including a ferromagnetic metal or an alloy of a ferromagnetic metal and a transition metal, or may also have a multi-layer structure including multiple layers of a ferromagnetic metal or an alloy of a ferromagnetic metal and a transition metal. For example, the first ferromagnetic layer 103a and the second ferromagnetic layer 103c may each include a single-layer or multi-layer structure including Co, Fe, CoPt, FePt, CoFe, etc.

[0080] In such a structure of the pinned layer 103′, the first ferromagnetic layer 103a and the second ferromagnetic layer 103c can form an antiferromagnet through Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction with the help of the SAF coupling layer 103b. In other words, when the magnetization direction of the first ferromagnetic layer 103a and the magnetization direction of the second ferromagnetic layer 103c are opposite to each other, the pinned layer 103′ can have a stable state. For example, the first ferromagnetic layer 103a can be magnetized toward the lower surface, and the second ferromagnetic layer 103c can be magnetized toward the upper surface, or the first ferromagnetic layer 103a can be magnetized toward the upper surface, and the second ferromagnetic layer 103c can be magnetized toward the lower surface. The first ferromagnetic layer 103a and the second ferromagnetic layer 103c magnetized in opposite directions can cancel out their stray magnetic fields. Therefore, the first ferromagnetic layer 103 a and the second ferromagnetic layer 103 c magnetized in opposite directions may be used to reduce or prevent a stray magnetic field generated in the pinned layer 103 from affecting the free layer 105 .

[0081] Figure 8 The magnetic tunnel junction device 100b is shown to include a double-layer seed layer 102, but the magnetic tunnel junction device 100b may also include Figure 7 When the magnetic tunnel junction device 100b includes the seed layer 102 having a double-layer structure, the first ferromagnetic layer 103a may be formed on the second seed layer 102b. When the magnetic tunnel junction device 100b includes the seed layer 102' having a triple-layer structure, the first ferromagnetic layer 103a may be formed on the third seed layer 102c.

[0082] Fig. 9 FIG. 1 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device 100 c according to another example embodiment. Fig. 9, the magnetic tunnel junction device 100c may further include a polarization enhanced layer 108 disposed between the pinned layer 103′ and the tunnel barrier layer 104. In this case, the pinned layer 103′, the polarization enhanced layer 108, the tunnel barrier layer 104, and the free layer 105 may be sequentially formed on the upper surface of the seed layer 102. The polarization enhanced layer 108 facilitates the growth of the tunnel barrier layer 104 and the free layer 105 on the pinned layer 103′. In addition, the polarization enhanced layer 108 may have a crystal structure similar to that of the tunnel barrier layer 104 or the free layer 105, and may further improve the crystal quality of the tunnel barrier layer 104 and the free layer 105 formed on the pinned layer 103′. To this end, the polarization enhanced layer 108 may include a ferromagnetic material similar to the free layer 105. For example, the polarization enhancement layer 108 may include at least one of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), an alloy containing Fe, an alloy containing Co, an alloy containing Ni, an alloy containing Mn, or a Heusler alloy. In addition, the polarization enhancement layer 108 may further include boron. For example, the polarization enhancement layer 108 may include CoFeB. The thickness of the polarization enhancement layer 108 may be 0.5 nm or more and about 1 nm or less. The polarization enhancement layer 108 may be applied not only to Fig. 9 The magnetic tunnel junction device 100c shown in FIG. 1 can also be applied to Figure 1 or the magnetic tunnel junction device 100 or 100a shown in FIG. 7 .

[0083] Fig.10 FIG. 1 is a cross-sectional view showing a schematic structure of a magnetic tunnel junction device 100d according to another example embodiment. Fig.10 , the magnetic tunnel junction device 100d may include a seed layer 112 having a single-layer structure including rhenium (Re). The seed layer 112 may include, for example, an alloy including rhenium (Re) of an HCP structure. For example, the rhenium alloy may include an alloy of rhenium and at least one metal of ruthenium (Ru), platinum (Pt), gold (Au), iridium (Ir), or cobalt (Co). According to example embodiments, the ratio of rhenium (Re) in the seed layer 112 may be 50 atomic % or greater, and the ratio of metals other than rhenium (Re) may be 50 atomic % or less. For example, the ratio of rhenium (Re) in the seed layer 112 may be between about 50 atomic % or greater and about 90 atomic % or less, and the ratio of metals other than rhenium (Re) may be between about 50 atomic % or less and about 10 atomic % or greater. An alloy of rhenium and at least one metal of ruthenium (Ru), platinum (Pt), gold (Au), iridium (Ir), or cobalt (Co) may form a stable HCP structure.

[0084] The seed layer 112 of a single-layer structure including a rhenium alloy having an HCP structure may be formed by using a sputtering method. For example, sputtering may be performed by providing argon (Ar) gas and / or krypton (Kr) gas while maintaining the temperature in the chamber at room temperature or higher (e.g., about 400° C. or higher), and applying a radio frequency (RF) power in a range between about 50 W and about 500 W. The target material may include at least one metal of rhenium (Re) metal and ruthenium (Ru), platinum (Pt), gold (Au), iridium (Ir), or cobalt (Co). At this time, argon (Ar) gas may be provided to the chamber at a flow rate of about 15 standard cc / minute (sccm) or more and 200 sccm or less, and krypton (Kr) gas may be provided to the chamber at a flow rate of about 10 sccm or more and 100 sccm or less.

[0085] Except for the seed layer 112 Fig.10 The configuration of the magnetic tunnel junction device 100d shown in FIG. Figure 1 Alternatively, except for the seed layer 112, the magnetic tunnel junction device 100 shown in FIG. Fig.10 The configuration of the magnetic tunnel junction device 100d shown in FIG. Figure 8 The configuration of the magnetic tunnel junction device 100b or 100c shown in or 9 is the same.

[0086] Fig.11 The structure of a memory cell MC including a magnetic tunnel junction device 100 according to an embodiment is schematically shown. Fig.11 , the memory cell MC may include the above-mentioned magnetic tunnel junction device 100 and a switching device TR connected to the magnetic tunnel junction device 100. The switching device TR may be a thin film transistor. The memory cell MC may be connected between the bit line BL and the word line WL. The bit line BL and the word line WL may be arranged to cross each other, and the memory cell MC may be arranged at the intersection of the bit line BL and the word line WL. The bit line BL may be electrically connected to the free layer 105 of the magnetic tunnel junction device 100, and the word line WL may be connected to the gate (gate) of the switching device TR. In addition, the drain (drain) of the switching device TR may be electrically connected to the lower electrode 101 of the magnetic tunnel junction device 100, and the source (source) of the switching device TR may be electrically connected to the source line SL. In such a structure, a write current, a read current, and an erase current may be applied to the memory cell MC through the word line WL and the bit line BL.

[0087] Fig.12 To display Fig.11 FIG. 1 is a perspective view of an arrangement structure of a magnetic tunnel junction device 100 and a switching device TR in a memory cell MC. Fig.12, the switching device TR may include, for example, a semiconductor substrate SUB, a source region SR, a source electrode SE, a channel CH, a drain region DR, a drain electrode DE, a gate insulating layer GI, and a gate G. The source electrode SE may be electrically connected to the source line SL, and the drain electrode DE may be electrically connected to the magnetic tunnel junction device 100 through the first wiring WL1 and the second wiring WL2. The first wiring WL1 may extend in a horizontal direction on the same layer as the source line SL, and the second wiring WL2 may extend in a vertical direction between the first wiring WL1 and the magnetic tunnel junction device 100. The bit line BL may be disposed on the magnetic tunnel junction device 100. When the switching device TR is turned on, current may flow from the source line SL through the source electrode SE, the source region SR, the channel CH, the drain region DR, the drain electrode DE, the first wiring WL1, the second wiring WL2, and the magnetic tunnel junction device 100 to the bit line BL. The current flowing through the bit line BL may vary depending on the resistance of the magnetic tunnel junction device 100.

[0088] exist Fig.12 In the embodiment, the empty space between the switching device TR, the source line SL, the first wiring WL1, the second wiring WL2, the magnetic tunnel junction device 100 and the bit line BL may be filled with a passivation layer including a dielectric material having an insulating property. For example, after the magnetic tunnel junction device 100 is formed on the first wiring WL1, subsequent processes may be performed, such as a process of filling the empty space with a dielectric material, a process of forming the bit line BL, a process of filling the dielectric material again on the bit line BL, and a process of forming another driving circuit and wiring. Even when a high-temperature heat treatment of about 400° C. or higher is performed in such a subsequent process, the pinned layer 103 of the magnetic tunnel junction device 100 according to the above example embodiment may hardly deteriorate.

[0089] at the same time, Fig.11 and 12 The display memory cell MC includes Figure 1 , but the memory cell MC may also include a magnetic tunnel junction device according to other example embodiments. For example, the memory cell MC may include Figures 7 to 10 Magnetic tunnel junction devices 100a, 100b, 100c and 100d are shown in FIG.

[0090] Fig.13 2 is a circuit diagram schematically showing a configuration of a memory device 200 including a plurality of memory cells MC. Fig.13 , the memory device 200 may include a plurality of bit lines BL, a plurality of word lines WL, a plurality of source lines SL, a plurality of memory cells MC respectively disposed at intersections of the plurality of bit lines BL and the plurality of word lines WL, a detection circuit 201 for detecting current from the plurality of bit lines BL, a word line driver 202 for applying current to the plurality of word lines WL, and a source line driver 203 for applying current to the plurality of source lines SL. Each memory cell MC may have a Fig.11 and 12 The configuration shown in . Fig.13 The storage device 200 shown in FIG. 1 may be a magnetic random access memory (MRAM) and may be used in electronic devices using non-volatile memory. For example, Fig.13 The memory device 200 shown in FIG. 2 may be a STT-MRAM or a SOT-MRAM.

[0091] Fig.14 Schematically displayed Fig.13 2 shows a cross-sectional structure of a plurality of memory cells MC of the memory device 200. Fig.14 , a plurality of memory cells MC may be arranged on a substrate SUB. Fig.14 In the cross-sectional view of FIG. 1 , a plurality of drain regions DR, a plurality of drain electrodes DE, a plurality of first wirings WL1, a plurality of second wirings WL2, a plurality of magnetic tunnel junction devices 100, and a plurality of bit lines BL are shown, but other configurations of the memory cell MC may be in a configuration having the same Fig.14 The memory device 200 may further include a passivation layer 210 filled between the plurality of memory cells MC. As described above, the pinned layer 103 of the magnetic tunnel junction device 100 according to some example embodiments of the present disclosure may hardly deteriorate in a subsequent process for forming the passivation layer 210 and the bit line BL.

[0092] The storage device 200 can be used to store data in various electronic devices. Fig.15 FIG. 1 is a conceptual diagram schematically showing a device architecture applicable to an electronic device 300 according to an example embodiment. Fig.15 , the electronic device 300 may include a main memory 310, an auxiliary memory 320, a central processing unit (CPU) 330, and an input / output device 340. The CPU 330 may include a cache (high-speed cache) memory 331, an arithmetic logic unit (ALU) 332, and a control unit 333. The cache memory 331 may include a static random access memory (SRAM). The main memory 310 may include a DRAM device, and the auxiliary memory 320 may include the storage device 200 according to the above-mentioned example embodiment. The cache memory 331, the main memory 310, and the auxiliary memory 320 may all include the storage device 200 according to the above-mentioned example embodiment. In some cases, the electronic device 300 may be implemented in a form in which a computing unit device and a memory unit device are adjacent to each other in one chip without distinguishing between the above-mentioned sub-units.

[0093] Any functional block shown in the figure and described above can be implemented by a processing circuit system such as hardware including logic circuits, a hardware / software combination such as a processor that executes software, or a combination thereof. For example, the processing circuit system may more specifically include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a system on a chip (SoC), a programmable logic unit, a microprocessor, an application specific integrated circuit (ASIC), etc.

[0094] It should be understood that some example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects in disclosed example embodiments should typically be considered as applicable to other similar features or aspects in other example embodiments. Although one or more example embodiments have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope defined by the appended claims.

Claims

1. Magnetic tunnel junction device, including: Seed layer; a pinned layer on the seed layer; a free layer facing the pinned layer; as well as a tunnel barrier layer between the pinned layer and the free layer, wherein the seed layer comprises a first seed layer and a second seed layer, and the second seed layer is between the first seed layer and the pinned layer, and One of the first seed layer and the second seed layer includes rhenium (Re), and the other of the first seed layer and the second seed layer includes ruthenium (Ru). 2 . The magnetic tunnel junction device of claim 1 , wherein the first seed layer comprises rhenium (Re), and the second seed layer comprises ruthenium (Ru). 3 . The magnetic tunnel junction device of claim 2 , wherein a thickness of the first seed layer is 50% or more of a total thickness of the seed layer. 4 . The magnetic tunnel junction device of claim 1 , wherein the first seed layer comprises ruthenium (Ru), and the second seed layer comprises rhenium (Re). 5 . The magnetic tunnel junction device of claim 4 , wherein a thickness of the second seed layer is 50% or more of a total thickness of the seed layer. 6 . The magnetic tunnel junction device of claim 1 , wherein the seed layer further comprises a third seed layer between the second seed layer and the pinned layer. 7 . The magnetic tunnel junction device of claim 6 , wherein the first seed layer comprises rhenium (Re), the second seed layer comprises ruthenium (Ru), and the third seed layer comprises rhenium (Re). 8 . The magnetic tunnel junction device of claim 7 , wherein a sum of a thickness of the first seed layer and a thickness of the third seed layer is 50% or more of a total thickness of the seed layer. 9 . The magnetic tunnel junction device of claim 6 , wherein the first seed layer comprises ruthenium (Ru), the second seed layer comprises rhenium (Re), and the third seed layer comprises ruthenium (Ru). 10 . The magnetic tunnel junction device of claim 9 , wherein a thickness of the second seed layer is 50% or more of a total thickness of the seed layer.

11. Magnetic tunnel junction device, comprising: Seed layer; a pinned layer on the seed layer; a free layer facing the pinned layer; as well as a tunnel barrier layer between the pinned layer and the free layer, The seed layer is a single layer including a rhenium (Re) alloy having a hexagonal close-packed (HCP) structure.

12. The magnetic tunnel junction device of claim 11, wherein the rhenium alloy comprises an alloy of rhenium (Re) and at least one metal of ruthenium (Ru), platinum (Pt), gold (Au), iridium (Ir) or cobalt (Co).

13. The magnetic tunnel junction device of claim 12, wherein a ratio of rhenium (Re) in the seed layer is 50 atomic % or greater, and a ratio of the at least one metal is 50 atomic % or less based on the total number of atoms in the seed layer.

14. The magnetic tunnel junction device of claim 1 or 11, wherein the total thickness of the seed layer is 1 nm or more and 10 nm or less.

15. The magnetic tunnel junction device according to claim 1 or 11, wherein The pinned layer includes a first ferromagnetic layer adjacent to the seed layer, a second ferromagnetic layer adjacent to the tunnel barrier layer, and a synthetic antiferromagnetic coupling layer between the first ferromagnetic layer and the second ferromagnetic layer, and The magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are opposite to each other.

16. The magnetic tunnel junction device of claim 15, wherein the synthetic antiferromagnetic coupling layer comprises a conductive metal.

17. The magnetic tunnel junction device according to claim 1 or 11, further comprising: A polarization enhanced layer is between the pinned layer and the tunnel barrier layer and includes a ferromagnetic material.

18. Storage devices, including: A plurality of memory cells, each of which comprises a magnetic tunnel junction device as claimed in any one of claims 1 to 17 and a switch device connected to the magnetic tunnel junction device.

19. The storage device of claim 18, further comprising: A passivation layer is provided between the plurality of memory cells.

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