Magnetic storage device

Abstract

According to one embodiment, a magnetic storage device includes first and second magnetic layers and a non-magnetic layer. The non-magnetic layer includes a first oxide layer containing magnesium and oxygen, a second oxide layer containing magnesium and oxygen, a third oxide layer containing zinc and oxygen, a fourth oxide layer containing a first predetermined element and oxygen, and a fifth oxide layer containing a second predetermined element and oxygen. The crystal structures of the oxides of the first and second predetermined elements are each rock salt structures. The first and second predetermined elements each have a higher oxide formation free energy than the oxide of zinc, and each oxide has a narrower band gap than the oxide of magnesium.

Description

Technical Field

[0001] The embodiments described herein are generally related to a magnetic storage device. [Cross-reference to related applications]

[0002] This application is based on and asserts priority to Japanese Patent Application No. 2022-145992, filed September 14, 2022, and U.S. Patent Application No. 18 / 178469, filed March 3, 2023, the entire contents of which are incorporated herein by reference. Prior Technology

[0003] A magnetic storage device that integrates magnetoresistive elements onto a semiconductor substrate has been proposed. Summary of the Invention

[0004] An embodiment provides a magnetic storage device including a magnetoresistive element with excellent properties.

[0005] Generally speaking, according to one embodiment, a magnetic storage device is provided, the magnetic storage device including a first magnetic layer, a second magnetic layer, and a non-magnetic layer. The first magnetic layer has a variable magnetization direction, the second magnetic layer has a fixed magnetization direction, and the non-magnetic layer is disposed between the first magnetic layer and the second magnetic layer. The non-magnetic layer includes: a first oxide layer disposed between the first and second magnetic layers and containing magnesium (Mg) and oxygen (O); a second oxide layer disposed between the second magnetic layer and the first oxide layer and containing magnesium (Mg) and oxygen (O); a third oxide layer disposed between the first and second oxide layers and containing zinc (Zn) and oxygen (O); a fourth oxide layer disposed between the first magnetic layer and the first oxide layer and containing a first predetermined element and oxygen (O); and a fifth oxide layer disposed between the second magnetic layer and the second oxide layer and containing a second predetermined element and oxygen (O). The crystal structures of the oxides of the first predetermined element and the second predetermined element are each rock salt structures. The first predetermined element and the second predetermined element each have a higher oxide formation free energy than the oxide of zinc (Zn), and the oxides of the first predetermined element and the second predetermined element each have a narrower band gap than the oxide of magnesium (Mg). Simple Explanation of the Diagram

[0006] Figure 1 is a schematic cross-sectional view showing the configuration of a magnetic storage device according to a first embodiment. Figure 2 is a schematic diagram illustrating the potential energy of Zn in the tunnel barrier layer according to the first embodiment. Figure 3 is a diagram showing whether the oxides of various elements shown in the periodic table have a B1 structure. Figure 4 is an Ellingham diagram showing the formation free energies of various element monoxides. Figure 5 is a diagram showing the band gaps of oxides of various elements. Figure 6 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a first modified example of the first embodiment. Figure 7 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a second modified example of the first embodiment. Figure 8 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a third modified example of the first embodiment. Figure 9 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a fourth modified example of the first embodiment. Figure 10 is a schematic cross-sectional view showing the configuration of a magnetic storage device according to a second embodiment. Figure 11 is a schematic diagram illustrating the potential energy of Zn1-αYα in the tunnel barrier layer according to the second embodiment. Figure 12 is a graph showing the calculated energy difference between the system in which the oxide layer is located between the MgO layers and the system in which the oxide layer is located near the interface between the MgO layer and the magnetic layer. Figure 13 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a first modified example of the second embodiment. Figure 14 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a second modified example of the second embodiment. Figure 15 is a perspective view schematically illustrating the configuration of a magnetic storage device according to an application example of the magnetoresistive effect element described in the first and second embodiments. Implementation

[0007] The embodiments will be described below with reference to the drawings. (First Embodiment)

[0008] Figure 1 is a schematic cross-sectional view illustrating the configuration of the magnetic storage device according to this embodiment. Specifically, Figure 1 is a schematic cross-sectional view illustrating the configuration of the magnetoresistive effect element 100. The magnetoresistive effect element 100 is a magnetic tunnel junction (MTJ) element.

[0009] A magnetoresistive element 100 is disposed on the lower structure (not shown) of a magnetic storage device, the magnetic storage device including a semiconductor substrate (not shown) and including a storage layer 10 as a magnetic layer, a reference layer 20 as a magnetic layer and a tunnel barrier layer 30 as a non-magnetic layer.

[0010] Storage layer 10 is a ferromagnetic layer with variable magnetization direction and includes an FeCoB layer containing iron (Fe), cobalt (Co), and boron (B). Variable magnetization direction means that the magnetization direction changes relative to a predetermined write current flowing through the ferromagnetic layer.

[0011] Reference layer 20 is a ferromagnetic layer with a fixed magnetization direction and includes an FeCoB layer containing iron (Fe), cobalt (Co), and boron (B). A fixed magnetization direction means that the magnetization direction will not change relative to a predetermined write current flowing through the ferromagnetic layer.

[0012] The tunnel barrier layer 30 is an insulating layer disposed between the storage layer 10 and the reference layer 20. The tunnel barrier layer 30 includes: an oxide layer 31 disposed between the storage layer 10 and the reference layer 20; an oxide layer 32 disposed between the reference layer 20 and the oxide layer 31; an oxide layer 33 disposed between the oxide layers 31 and 32; an oxide layer 34a disposed between the storage layer 10 and the oxide layer 31; and an oxide layer 35a disposed between the reference layer 20 and the oxide layer 32. The tunnel barrier layer 30 will be described in detail below.

[0013] When the magnetization direction of storage layer 10 is parallel to the magnetization direction of reference layer 20, the magnetoresistive element 100 is in a low-resistance state. Furthermore, when the magnetization direction of storage layer 10 is antiparallel to the magnetization direction of reference layer 20, the magnetoresistive element 100 is in a high-resistance state. Due to this characteristic, the magnetoresistive element 100 can store binary data according to its resistance state (low-resistance state, high-resistance state).

[0014] The magnetoresistive effect element 100 is a spin transfer torque (STT) type magnetoresistive effect element with perpendicular magnetization, and the magnetization direction of the storage layer 10 is perpendicular to the main surface of the storage layer 10, while the magnetization direction of the reference layer 20 is perpendicular to the main surface of the reference layer 20.

[0015] The tunnel barrier layer 30 will be described in detail below.

[0016] The oxide layer 31 is formed of an MgO layer containing magnesium (Mg) and oxygen (O). That is, the oxide layer 31 is made of a magnesium (Mg) oxide. The oxide layer 31 is in contact with the oxide layers 33 and 34a.

[0017] The oxide layer 32 is formed of an MgO layer containing magnesium (Mg) and oxygen (O). That is, the oxide layer 32 is made of magnesium (Mg) oxide. The oxide layer 32 is in contact with the oxide layer 33 and the oxide layer 35a.

[0018] The oxide layer 33 is formed of a ZnO layer containing zinc (Zn) and oxygen (O). That is, the oxide layer 33 is formed of an oxide of zinc (Zn). The oxide layer 33 is in contact with the oxide layers 31 and 32.

[0019] The oxide layer 34a is formed of an XO layer containing a predetermined element X and oxygen (O). That is, the oxide layer 34a is formed of an oxide of the predetermined element X. The predetermined element X is preferably iron (Fe). The oxide layer 34a is in contact with the oxide layer 31 and the storage layer 10.

[0020] The oxide layer 35a is formed of an XO layer containing a predetermined element X and oxygen (O). That is, the oxide layer 35a is formed of an oxide of the predetermined element X. The predetermined element X is preferably iron (Fe). The oxide layer 35a is in contact with the oxide layer 32 and the reference layer 20.

[0021] The predetermined element X in oxide layer 34a may be the same as or different from the predetermined element X in oxide layer 35a. In this embodiment, the predetermined element X in oxide layer 34a is the same as the predetermined element X in oxide layer 35a.

[0022] Using the configuration described above, in this embodiment, a tunnel barrier layer 30 with excellent properties can be obtained, and a magnetoresistive effect element with excellent properties can be obtained as described below.

[0023] Based on first-principles calculations and thermochemical E-models, it is predicted that the collapse voltage of a tunnel barrier layer with a structure that sandwiches ZnO layers between MgO layers is higher than that of a tunnel barrier layer formed solely by MgO layers.

[0024] However, it has been confirmed that when heat treatment is performed after forming a structure with ZnO layers sandwiched between MgO layers, Zn segregates near the interface between the storage layer and the tunnel barrier layer, and near the interface between the reference layer and the tunnel barrier layer. This may be because the structure with ZnO layers sandwiched between magnetic layers (storage layer, reference layer) and MgO layers is more energy-stable than the structure with ZnO layers sandwiched between MgO layers.

[0025] Zn is more stable than Mg when it is not bonded to oxygen. The magnetic layer is formed of an FeCoB layer or a similar layer and does not contain oxygen. Therefore, the stable state is that Zn is located near the interface between the magnetic layer and the tunnel barrier layer, while Mg is located in the center of the tunnel barrier layer. Therefore, it is thought that heat treatment or similar processes can be used to position the ZnO layer near the interface between the magnetic layer and the tunnel barrier layer, while the MgO layer is located in the center of the tunnel barrier layer.

[0026] In this embodiment, oxide layer 34a formed by the XO layer is located between storage layer 10 and oxide layer 31 formed by the MgO layer, while oxide layer 35a formed by the XO layer is located between reference layer 20 and oxide layer 32 formed by the MgO layer. This allows oxide layer 33 formed by the ZnO layer to be stably located between oxide layer 31 and oxide layer 32. The preferred conditions required for the predetermined element X will be described below.

[0027] First, the first condition will be explained. The crystal structure of MgO used as oxide layers 31 and 32 is a B1 structure (rock salt structure). Therefore, the crystal structure of XO used as oxide layers 34a and 35a is also preferably a B1 structure. That is, the crystal structure of oxide XO of the predetermined element X is preferably a B1 structure. Here, the B1 structure also includes a distorted B1 structure.

[0028] Next, the second condition will be explained. As mentioned above, Zn is stable when it is not bonded to oxygen. In other words, Zn has a large oxide formation free energy. In this embodiment, the XO layer is disposed near the interface between the magnetic layer and the tunnel barrier layer to prevent the ZnO layer from being located near the interface between the magnetic layer and the tunnel barrier layer. Therefore, the oxide formation free energy of the predetermined element X is preferably higher than that of Zn. Specifically, the formation free energy of the oxide (XO) of the predetermined element X is preferably higher than that of the oxide (ZnO) of Zn.

[0029] Figure 2 is a schematic diagram illustrating the potential energy of Zn in the tunnel barrier layer 30. In Figure 2, characteristic (a) corresponds to the case where oxide layers 34a and 35a formed of an oxide of a predetermined element X satisfying the second condition are provided, while characteristic (b) corresponds to the case where oxide layers 34a and 35a are not provided. Characteristic (b) shows a low potential energy near the storage layer (FeCoB layer) 10 and the reference layer (FeCoB layer) 20, while characteristic (a) shows a low potential energy at the position corresponding to the oxide layer (ZnO layer) 33. Therefore, by providing oxide layers 34a and 35a made of XO, oxide layer 33 made of ZnO can be stably located between oxide layers 31 and 32 made of MgO.

[0030] Next, the third condition will be explained. When the band gap of XO is wider than that of MgO, the resistance of the tunnel barrier layer 30 will increase. Therefore, it is preferable that the band gap of the oxide of the predetermined element X is narrower than that of the oxide of Mg. Specifically, the band gap of the oxide of the predetermined element X (XO) is preferably narrower than that of the oxide of Mg (MgO).

[0031] Figure 3 is a diagram showing whether the monoxides of various elements shown in the periodic table have a B1 structure (rock salt structure). In Figure 3, the monoxides of each of the marked elements have a B1 structure (including distorted B1 structures).

[0032] Figure 4 is an Ellingham plot showing the formation free energy (standard formation Gibbs energy) of the monoxides of various elements. The horizontal axis represents temperature, and the vertical axis represents formation free energy. As can be seen from Figure 4, at least within the temperature range shown in Figure 4, the formation free energy of iron (Fe) monoxide (FeO) is greater than that of Zn monoxide (ZnO).

[0033] Figure 5 shows the band gaps of the monoxides of various elements. As shown in Figure 5, the band gap of iron (Fe) monoxide (FeO) is narrower than that of Mg monoxide (MgO).

[0034] Based on the above considerations, iron (Fe) was selected as the predetermined element X that satisfies the first, second, and third conditions.

[0035] As described above, in this embodiment, by using oxide layers 34a and 35a containing a predetermined element X and oxygen (O), a tunnel barrier layer 30 with excellent properties of high withstand voltage and energy stability can be obtained. Therefore, a magnetoresistive effect element with excellent characteristics can be obtained.

[0036] Figure 6 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a first modified example of this embodiment.

[0037] In this modified example, oxide layers 34b and 35b are formed of a Mg1-αXαO layer (where 0 < α < 1) containing magnesium (Mg) in addition to a predetermined element X (preferably iron (Fe)) and oxygen (O). That is, oxide layers 34b and 35b are formed of an oxide containing magnesium (Mg), the predetermined element X, and oxygen (O). Preferably, the concentration of magnesium (Mg) in oxide layer 34b decreases with increasing distance from oxide layer 31, and the concentration of magnesium (Mg) in oxide layer 35b decreases with increasing distance from oxide layer 32.

[0038] Similarly, in this modified example, by providing oxide layer 34b and oxide layer 35b containing predetermined element X, the same effect as in the above embodiment can be obtained.

[0039] Figure 7 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a second modified example of this embodiment.

[0040] Similarly, in this modified example, oxide layers 34c and 35c contain a predetermined element X (preferably iron (Fe)) and oxygen (O). Note that in this modified example, the composition ratio of the predetermined element X to oxygen (O) is not 1:1, and oxide layers 34c and 35c are formed from an X1-αOα layer (where 0 < α < 1). Therefore, oxide layers 34c and 35c need not be oxides.

[0041] Similarly, in this modified example, by providing oxide layer 34c and oxide layer 35c containing predetermined element X, the same effect as in the above embodiment can be obtained.

[0042] Figure 8 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a third modified example of this embodiment.

[0043] Similarly, in this modified example, oxide layers 34d and 35d contain a predetermined element X (preferably iron (Fe)) and oxygen (O). Note that in this modified example, oxide layer 34d includes oxide layers 34d1 and 34d2, while oxide layer 35d includes oxide layers 35d1 and 35d2.

[0044] The basic configurations of oxide layers 34d1 and 35d1 are similar to those of oxide layers 34a and 35a shown in Figure 1. That is, oxide layers 34d1 and 35d1 are formed from an XO layer (an oxide layer of predetermined element X) containing a predetermined element X and oxygen (O).

[0045] The basic configurations of oxide layers 34d2 and 35d2 are similar to those of oxide layers 34c and 35c shown in Figure 7. That is, oxide layers 34d2 and 35d2 are formed from an X1-αOα layer containing a predetermined element X and oxygen (O) (where 0 < α < 1).

[0046] Similarly, in this modified example, by providing oxide layer 34d and oxide layer 35d containing predetermined element X, the same effect as in the above embodiment can be obtained.

[0047] Figure 9 is a cross-sectional view schematically showing the configuration of a magnetic storage device according to a fourth modified example of this embodiment.

[0048] Similarly, in this modified example, oxide layers 34e and 35e contain a predetermined element X (preferably iron (Fe)) and oxygen (O). Note that in the modified example, oxide layer 34e includes oxide layers 34e1 and 34e2, while oxide layer 35e includes oxide layers 35e1 and 35e2.

[0049] The basic configurations of oxide layers 34e1 and 35e1 are similar to those of oxide layers 34b and 35b shown in FIG. 6. That is, oxide layers 34e1 and 35e1 are formed of Mg1-αXαO layers (where 0 < α < 1) containing magnesium (Mg), a predetermined element X, and oxygen (O). As described in the first modified example, it is preferable that the concentration of magnesium (Mg) in oxide layer 34e1 decreases with increasing distance from oxide layer 31, while the concentration of magnesium (Mg) in oxide layer 35e1 decreases with increasing distance from oxide layer 32.

[0050] The basic configurations of oxide layers 34e2 and 35e2 are similar to those of oxide layers 34a and 35a shown in Figure 1 or oxide layers 34c and 35c shown in Figure 7. That is, oxide layers 34e2 and 35e2 are formed from an X1-αOα layer (where 0 < α < 1) containing a predetermined element X and oxygen (O) and substantially no magnesium (Mg).

[0051] Similarly, in this modified example, by providing oxide layers 34e and 35e containing a predetermined element X, the same effect as in the above embodiment can be obtained. (Second Embodiment)

[0052] Next, the second embodiment will be described. The basic situation is the same as that of the first embodiment, and the description of the situation in the first embodiment will not be repeated.

[0053] Figure 10 is a schematic cross-sectional view illustrating the configuration of the magnetic storage device according to this embodiment. Specifically, Figure 10 is a schematic cross-sectional view illustrating the configuration of the magnetoresistive element 100. The magnetoresistive element 100 is a magnetic tunnel junction (MTJ) element.

[0054] Similar to the first embodiment, the magnetoresistive effect element 100 is disposed on the lower structure (not shown) of the magnetic storage device, which includes a semiconductor substrate (not shown) and includes a storage layer 10, a reference layer 20 and a non-magnetic tunnel barrier layer 40.

[0055] In this embodiment, the tunnel barrier layer 40 includes: an oxide layer 41 disposed between the storage layer 10 and the reference layer 20; an oxide layer 42 disposed between the reference layer 20 and the oxide layer 41; and an oxide layer 43 disposed between the oxide layer 41 and the oxide layer 42.

[0056] The oxide layer 41 is formed of an MgO layer containing magnesium (Mg) and oxygen (O). That is, the oxide layer 41 is made of magnesium (Mg) oxide. The oxide layer 41 is in contact with the storage layer 10 and the oxide layer 43.

[0057] The oxide layer 42 is formed of an MgO layer containing magnesium (Mg) and oxygen (O). That is, the oxide layer 42 is formed of a magnesium (Mg) oxide. The oxide layer 42 is in contact with the reference layer 20 and the oxide layer 43.

[0058] Oxide layer 43 is formed of a Zn1-αYαO layer (where 0 < α < 1) containing zinc (Zn), a predetermined element Y, and oxygen (O). That is, oxide layer 43 is formed of an oxide containing zinc (Zn), a predetermined element Y, and oxygen (O). The predetermined element Y is preferably selected from cadmium (Cd), manganese (Mn), barium (Ba), strontium (Sr), and calcium (Ca). Oxide layer 43 is in contact with oxide layers 41 and 42.

[0059] Using the configuration described above, in this embodiment, a tunnel barrier layer 40 with excellent properties can be obtained, and a magnetoresistive effect element with excellent properties can be obtained as described below.

[0060] As described in the first embodiment, the tunnel barrier layer with a structure in which a ZnO layer is sandwiched between MgO layers has a high collapse voltage but is unstable in terms of energy.

[0061] In this embodiment, the oxide layer 43 formed by the Zn1-αYαO layer containing zinc (Zn), a predetermined element Y, and oxygen (O) is located between the oxide layer 41 formed by the MgO layer and the oxide layer 42 formed by the MgO layer. Therefore, the oxide layer 43 formed by the Zn1-αYαO layer can be stably located between the oxide layer 41 and the oxide layer 42. The preferred conditions required for the predetermined element Y are described below.

[0062] First, the first condition will be explained. As described in the first embodiment, Zn has a large oxide formation free energy. In this embodiment, an oxide layer 43 is formed by using a Zn1-αYαO layer containing a predetermined element Y in addition to zinc (Zn) and oxygen (O), and the oxide layer 43 is stably located between oxide layers 41 and 42. Therefore, the oxide formation free energy of the predetermined element Y is preferably less than that of Zn. Specifically, the formation free energy of the oxide (YO) of the predetermined element Y is preferably less than that of the oxide (ZnO) of Zn.

[0063] Figure 11 is a schematic diagram illustrating the potential energy of Zn1-αYα in the tunnel barrier layer 40. In Figure 11, characteristic (a) corresponds to the case where the oxide layer 43 is formed from a Zn1-αYαO layer containing a predetermined element Y satisfying a first condition, while characteristic (b) corresponds to the case where the oxide layer 43 is formed from a ZnO layer that does not contain the predetermined element Y. As shown in Figure 11, at the position corresponding to the oxide layer 43, characteristic (a) shows a lower potential energy than characteristic (b). Therefore, by forming the oxide layer 43 from the Zn1-αYαO layer, the oxide layer 43 can stably exist between the oxide layer 41 and the oxide layer 42 formed from MgO.

[0064] Next, the second condition will be explained. When the band gap of Zn1-αYαO is wider than that of MgO, the resistance of the tunnel barrier layer 40 will increase. Therefore, it is preferable that the band gap of Zn1-αYαO is narrower than that of MgO. As shown in Figure 5, the band gap of ZnO is narrower than that of MgO. Therefore, when the band gap of YO is narrower than that of MgO, the band gap of Zn1-αYαO is also narrower than that of MgO. Therefore, it is preferable that the band gap of the oxide of the predetermined element Y is narrower than that of the oxide of Mg. Specifically, it is preferable that the band gap of the oxide of the predetermined element Y (YO) is narrower than that of the oxide of Mg (MgO).

[0065] As can be seen from Figure 4, at least within the temperature range shown in Figure 4, the formation free energy of each of the oxides of cadmium (Cd), manganese (Mn), barium (Ba), strontium (Sr), and calcium (Ca) (CdO, MnO, BaO, SrO, and CaO) is less than that of the oxide of Zn (ZnO).

[0066] As shown in Figure 5, the band gaps of each of the oxides of cadmium (Cd), manganese (Mn), barium (Ba), strontium (Sr), and calcium (Ca) (CdO, MnO, BaO, SrO, and CaO) are narrower than those of the oxide of Mg (MgO).

[0067] Based on the above considerations, cadmium (Cd), manganese (Mn), barium (Ba), strontium (Sr), and calcium (Ca) were selected as the predetermined element Y that satisfies the first and second conditions.

[0068] Furthermore, in this embodiment, it is not always necessary to meet the condition corresponding to the first condition described in the first embodiment (the crystal structure of the oxide YO of the predetermined element Y is a B1 structure). As shown in Figure 3, Cd and Mn satisfy this condition, while Ba, Sr, and Ca do not. In this embodiment, it is crucial that the original crystal structure of ZnO does not collapse when the predetermined element Y is added to ZnO. The Cd, Mn, Ba, Sr, and Ca described above can also prevent the collapse of the original crystal structure of ZnO even when added to ZnO.

[0069] Figure 12 is a graph showing the calculated energy difference ΔE (ΔE = E1 - E2) between the energy E1 in a system where oxide layer A (which is a ZnO layer, CaO layer, or Zn0.5Ca0.5O layer) is located between MgO layers and the energy E2 in a system where oxide layer A is located near the interface between the MgO layer and the magnetic layer (Fe layer). In Figure 12, the value of the energy difference ΔE for the ZnO layer is normalized to 1. A larger value of energy difference ΔE indicates that oxide layer A is more likely to remain stable near the interface.

[0070] As shown in Figure 12, the Zn0.5Ca0.5O layer exhibits the smallest energy difference ΔE. Therefore, it can be seen that the Zn0.5Ca0.5O layer is less stable near the interface between the MgO layer and the magnetic layer compared to the ZnO and CaO layers. In other words, the Zn0.5Ca0.5O layer is more likely to remain stable between the MgO layers than the ZnO and CaO layers.

[0071] Therefore, by forming oxide layer 43 from Zn1-αCaαO layers, oxide layer 43 can be stably positioned between oxide layer 41 and oxide layer 42 formed from MgO. For other predetermined elements Y (Cd, Mn, Ba, Sr), similarly to Ca, it is envisioned that by forming oxide layer 43 from Zn1-αYαO layers, oxide layer 43 can be stably positioned between oxide layer 41 and oxide layer 42 formed from MgO.

[0072] As described above, in this embodiment, by using a Zn1-αYαO layer containing zinc (Zn), a predetermined element Y, and oxygen (O) as the oxide layer 43, a tunnel barrier layer 40 with excellent properties of high breakdown voltage and energy stability can be obtained, as in the first embodiment. Therefore, a magnetoresistive effect element with excellent characteristics can be obtained.

[0073] Figure 13 is a schematic cross-sectional view showing the configuration (configuration of magnetoresistive element 100) of a magnetic storage device according to a first modified example of this embodiment.

[0074] In this modified example, oxide layer 44 is disposed between oxide layer 41 and oxide layer 43, while oxide layer 45 is disposed between oxide layer 42 and oxide layer 43. The basic configuration of oxide layers 41, 42, and 43 is similar to that of the above embodiment. Oxide layers 44 and 45 contain a predetermined element Y and oxygen (O) and substantially do not contain zinc (Zn). Specifically, oxide layers 44 and 45 are formed from an oxide (YO) of the predetermined element Y (preferably Cd, Mn, Ba, Sr, or Ca).

[0075] Similarly, in this modified example, by using a Zn1-αYαO layer containing zinc (Zn), a predetermined element Y, and oxygen (O) as the oxide layer 43, the same effect as in the above embodiment can be obtained.

[0076] Figure 14 is a schematic cross-sectional view showing the configuration (configuration of magnetoresistive element 100) of a magnetic storage device according to a second modified example of this embodiment.

[0077] In this modified example, oxide layer 46 is disposed between oxide layers 41 and 43, and oxide layer 47 is disposed between oxide layers 42 and 43. The basic configuration of oxide layers 41, 42, and 43 is the same as in the above embodiment. Oxide layers 46 and 47 are formed of Mg1-αYαO (where 0 < α < 1) containing magnesium (Mg), a predetermined element Y, and oxygen (O). That is, oxide layers 46 and 47 are formed of an oxide containing magnesium (Mg) and the predetermined element Y. Preferably, the concentration of magnesium (Mg) in oxide layer 46 decreases with increasing distance from oxide layer 41, and the concentration of magnesium (Mg) in oxide layer 47 decreases with increasing distance from oxide layer 42.

[0078] Similarly, in this modified example, by using a Zn1-αYαO layer containing zinc (Zn), a predetermined element Y, and oxygen (O) as the oxide layer 43, the same effect as in the above embodiment can be obtained.

[0079] Although the storage layer 10 is shown as a bottom free-type magnetoresistive effect element on the lower side of the reference layer 20 in the first and second embodiments described above, a top free-type magnetoresistive effect element on the upper side of the reference layer 20 can also be used.

[0080] Figure 15 is a perspective view schematically illustrating the configuration of a magnetic storage device according to an application example of the magnetoresistive effect element 100 described in the first and second embodiments.

[0081] Memory cell 300 is disposed between a first wiring 410 extending in the X direction and a second wiring 420 extending in the Y direction. Memory cell 300 includes a magnetoresistive element 100 as described in the first and second embodiments and a selector (which is a switching element) 200 connected in series with the magnetoresistive element 100. One of the first wiring 410 and the second wiring 420 corresponds to a word line, while the other of the first wiring 410 and the second wiring 420 corresponds to a bit line.

[0082] In Figure 15, the X, Y, and Z directions intersect each other. Specifically, the X, Y, and Z directions are orthogonal to each other.

[0083] Selector 200 is a two-terminal switching element with nonlinear current-voltage characteristics, and it has the characteristic of switching from an open state to an on state when the voltage applied between the two terminals exceeds a threshold voltage. Therefore, when a voltage is applied between the first wiring 410 and the second wiring 420 and the voltage applied to selector 200 exceeds the threshold voltage, selector 200 changes from an open state to an on state. Thus, current flows through magnetoresistive element 100 and selector 200, allowing writing or reading from magnetoresistive element 100.

[0084] By applying the magnetoresistive effect element 100 described in the first and second embodiments to the magnetic storage device shown in FIG15, a magnetic storage device with excellent characteristics can be obtained.

[0085] Although Figure 15 shows a configuration in which the magnetoresistive element 100 is disposed on the upper side of the selector 200, a configuration in which the magnetoresistive element 100 is disposed on the lower side of the selector 200 can also be used.

[0086] Although specific embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this disclosure. In fact, the novel embodiments described herein can be embodied in various other forms; furthermore, various omissions, substitutions, and changes can be made to the forms of the embodiments described herein without departing from the spirit of this disclosure. The appended claims and their equivalents are intended to cover such forms or modifications falling within the scope and spirit of this disclosure.

[0087] 10: Storage layer / FeCoB layer 20: Reference layer / FeCoB layer 30, 40: Tunnel barrier layer 31, 41: Oxide layer 32, 42: Oxide layer 33: Oxide layer / ZnO layer 34a, 34b, 34c, 34d, 34e: Oxide layers 34d1, 34d2, 34e1, 34e2, 35d1, 35d2, 35e1, 35e2: Oxide layer 35a, 35b, 35c, 35d, 35e: Oxide layers 43: Oxide layer 44: Oxide layer 45: Oxide layer 46: Oxide layer 47: Oxide layer 100: Magnetoresistive element 200: Selector (Switching Element) 300: Memory Cell 410: First wiring 420: Second wiring (a), (b): Characteristics X, Y, Z: Direction

Claims

1. A magnetic storage device, comprising a first magnetic layer, a second magnetic layer, and a non-magnetic layer, wherein the non-magnetic layer is disposed between the first magnetic layer and the second magnetic layer, and the non-magnetic layer comprises: A first oxide layer, disposed between the first magnetic layer and the second magnetic layer, contains magnesium (Mg) and oxygen (O); a second oxide layer, disposed between the second magnetic layer and the first oxide layer, contains magnesium (Mg) and oxygen (O); and a third oxide layer, disposed between the first oxide layer and the second oxide layer, contains zinc (Zn), a predetermined element, and oxygen (O), wherein the predetermined element has a lower oxide formation free energy than the oxide of zinc (Zn), and the oxide of the predetermined element has a narrower band gap than the oxide of magnesium (Mg).

2. The magnetic storage device as claimed in claim 1, wherein the first magnetic layer has a variable magnetization direction and the second magnetic layer has a fixed magnetization direction.

3. The magnetic storage device as claimed in claim 1, wherein the first magnetic layer and the second magnetic layer are each vertically magnetized.

4. The magnetic storage device as claimed in claim 1, further comprising: A magnetoresistive element includes a first magnetic layer, a second magnetic layer, and the non-magnetic layer; And a switching element, connected in series with the magnetoresistive effect element, wherein the magnetoresistive effect element and the switching element constitute a memory cell.

5. The magnetic storage device as claimed in claim 4, wherein the magnetoresistive element is a spin-transfer torque (STT) type magnetoresistive element.

6. The magnetic storage device as claimed in claim 4, further comprising: The first wiring extends along the first direction; And a second wiring extending along a second direction intersecting the first direction, wherein the magnetoresistive element and the switching element are connected in series between the first wiring and the second wiring.

7. The magnetic storage device as claimed in claim 1, wherein the crystal structure of the oxide of the predetermined element is a rock salt structure.

8. The magnetic storage device as claimed in claim 1, wherein the non-magnetic layer further comprises: A fourth oxide layer, disposed between the first oxide layer and the third oxide layer, contains the predetermined element and oxygen (O) and substantially does not contain zinc (Zn), and a fifth oxide layer, disposed between the second oxide layer and the third oxide layer, contains the predetermined element and oxygen (O) and substantially does not contain zinc (Zn).

9. The magnetic storage device as claimed in claim 1, wherein the non-magnetic layer further comprises: A sixth oxide layer is disposed between the first oxide layer and the third oxide layer and contains magnesium (Mg), the predetermined element and oxygen (O), and a seventh oxide layer is disposed between the second oxide layer and the third oxide layer and contains magnesium (Mg), the predetermined element and oxygen (O).

10. The magnetic storage device of claim 1, wherein the first magnetic layer and the second magnetic layer each contain iron (Fe), cobalt (Co) and boron (B).

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