Switching element and storage device
By introducing insulating materials with added elements into the switching material layer, a concentration distribution with peaks in the interface region is formed, which solves the problems of high threshold voltage and leakage current in storage devices and achieves performance improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KIOXIA CORP
- Filing Date
- 2022-12-13
- Publication Date
- 2026-07-14
Smart Images
Figure CN116264818B_ABST
Abstract
Description
[0001] Cross-references to related applications
[0002] This application is based on and claims priority to Japanese Patent Application No. 2021-203411, filed December 15, 2021, and U.S. Patent Application No. 17 / 898812, filed August 30, 2022, the entire contents of which are incorporated herein by reference. Technical Field
[0003] The embodiments described herein generally relate to switching elements and storage devices. Background Technology
[0004] A storage device is proposed in which memory cells are integrated on a semiconductor substrate, each memory cell including a variable resistance storage element such as a magnetoresistive element and a selector (e.g., a switching element). Summary of the Invention
[0005] An embodiment provides a storage device including a switching element with excellent characteristics.
[0006] Generally, according to one embodiment, the switching element includes: a first conductive layer; a second conductive layer; and a switching material layer disposed between the first conductive layer and the second conductive layer and formed of an insulating material containing an additive element. The switching material layer includes a first interface region and a second interface region, the first interface region comprising a first interface between the first conductive layer and the switching material layer, and the second interface region comprising a second interface between the second conductive layer and the switching material layer. The concentration of the additive element in the switching material layer has a first peak in the first interface region. Attached Figure Description
[0007] Figure 1 This is a perspective view schematically illustrating the configuration of the storage device according to the first embodiment.
[0008] Figure 2 This is a schematic cross-sectional view showing the configuration of the magnetoresistive effect element according to the first embodiment.
[0009] Figure 3 This is a schematic cross-sectional view showing the configuration of the selector according to the first embodiment.
[0010] Figure 4A This is a diagram schematically illustrating a first example of the concentration distribution of the added elements according to the first embodiment.
[0011] Figure 4B This is a diagram schematically illustrating a second example of the concentration distribution of the added elements according to the first embodiment.
[0012] Figure 4C This is a diagram schematically illustrating a third example of the concentration distribution of the added elements according to the first embodiment.
[0013] Figure 5 It is a graph showing the relationship between the voltage applied to the memory cell and the current flowing through the memory cell according to the first embodiment.
[0014] Figure 6A This is a graph showing the relationship between the threshold voltage and leakage current of the memory cell when the concentration of the added element changes according to the first embodiment.
[0015] Figure 6B This illustrates the first embodiment in Figure 6A A graph showing the concentration distribution along the thickness direction of the sample used.
[0016] Figure 7A This is a graph showing the relationship between the threshold voltage and leakage current of the memory cell when the concentration distribution of the added element changes according to the first embodiment.
[0017] Figure 7B This illustrates the first embodiment in Figure 7A A graph showing the concentration distribution along the thickness direction of the sample used.
[0018] Figure 8A This is a graph showing the relationship between the threshold voltage and leakage current of the memory cell when the concentration distribution of the added element changes according to the first embodiment.
[0019] Figure 8B This illustrates the first embodiment in Figure 8A A graph showing the radial concentration distribution of the samples used.
[0020] Figure 9 This is a diagram schematically illustrating a first example of a method for manufacturing a selector according to a first embodiment.
[0021] Figure 10 This is a diagram schematically illustrating a second example of a method for manufacturing a selector according to the first embodiment.
[0022] Figure 11A This is a diagram schematically illustrating a third example of a method for manufacturing a selector according to the first embodiment.
[0023] Figure 11B This is a diagram schematically illustrating a third example of a method for manufacturing a selector according to the first embodiment.
[0024] Figure 12The diagram shows a cross-sectional view schematically illustrating a modified configuration of the selector according to the first embodiment, and a diagram schematically illustrating the concentration distribution of the added elements.
[0025] Figure 13 This is a graph showing the relationship between the voltage applied to the memory cell and the current flowing through the memory cell when the concentration of the added element is not uniform in a plane perpendicular to the thickness direction of the selector material layer, according to the first embodiment.
[0026] Figure 14 It is a graph showing the relationship between the voltage applied to the memory cell and the current flowing through the memory cell when the concentration of the added element is uniform in a plane perpendicular to the thickness direction of the selector material layer according to the first embodiment.
[0027] Figure 15 The diagram illustrates a cross-sectional view of the selector configuration and a graph illustrating the concentration distribution of the added elements, according to the second embodiment.
[0028] Figure 16 The diagram shows a cross-sectional view schematically illustrating a modified configuration of the selector according to the second embodiment, and a diagram schematically illustrating the concentration distribution of the added elements. Detailed Implementation
[0029] In the following description, embodiments will be illustrated with reference to the accompanying drawings.
[0030] (First Embodiment)
[0031] Figure 1 This is a perspective view schematically illustrating the configuration of the storage device according to this embodiment.
[0032] Figure 1 The storage device shown is a non-volatile storage device and includes multiple first wirings 10, multiple second wirings 20, and multiple memory cells 30 connected between the multiple first wirings 10 and the multiple second wirings 20.
[0033] Each first wiring 10 extends in the X direction, and each second wiring 20 extends in the Y direction. One of the first wiring 10 and the second wiring 20 corresponds to a word line, while the other of the first wiring 10 and the second wiring corresponds to a bit line. Figure 1 The X, Y, and Z directions shown are intersecting directions. Specifically, the X, Y, and Z directions are orthogonal to each other.
[0034] Each memory cell 30 includes a magnetoresistive element 40 serving as a variable resistive storage element and a selector (e.g., a switching element) 50 connected in series with the magnetoresistive element 40. One end of the memory cell 30 is connected to a first wiring 10, and the other end of the memory cell 30 is connected to a second wiring 20. A magnetic tunnel junction (MTJ) element is used as the magnetoresistive element 40.
[0035] By applying a predetermined voltage between the first wiring 10 and the second wiring 20, the selector 50 is in a conducting state and can perform write and read operations on the magnetoresistive effect element 40 connected in series with the selector 50.
[0036] exist Figure 1 In the example shown, the magnetoresistive element 40 is disposed on the lower layer side and the selector 50 is disposed on the upper layer side. However, the magnetoresistive element 40 can be disposed on the upper layer side and the selector 50 can be disposed on the lower layer side.
[0037] Figure 2 This is a cross-sectional view schematically showing the configuration of the magnetoresistive element 40.
[0038] The magnetoresistive element 40 includes a storage layer 41, a reference layer 42, a tunnel barrier layer 43, an electrode 44, and an electrode 45, and has a stacked structure in which the storage layer 41, the reference layer 42, and the tunnel barrier layer 43 are disposed between the electrode 44 and the electrode 45.
[0039] Storage layer 41 is a ferromagnetic layer with a variable magnetization direction. A variable magnetization direction means that the magnetization direction changes relative to a predetermined write current. Reference layer 42 is a ferromagnetic layer with a fixed magnetization direction. A fixed magnetization direction means that the magnetization direction remains constant relative to a predetermined write current. Tunnel barrier layer 43 is a non-magnetic insulating layer disposed between storage layer 41 and reference layer 42.
[0040] When the magnetization direction of the storage layer 41 is parallel to the magnetization direction of the reference layer 42, the magnetoresistive element 40 is in a relatively low-resistance state. When the magnetization direction of the storage layer 41 is antiparallel to the magnetization direction of the reference layer 42, the magnetoresistive element 40 is in a relatively high-resistance state. Therefore, the magnetoresistive element 40 can store binary data according to its resistance state. Furthermore, the low-resistance state or the high-resistance state in the magnetoresistive element can be set according to the direction of the current flowing through it.
[0041] Figure 3 This is a cross-sectional view schematically showing the configuration of selector 50.
[0042] The selector 50 includes an electrode 51, an electrode 52, and a selector material layer (which is a switching material layer) 53, and the selector material layer 53 is disposed between the electrode 51 and the electrode 52.
[0043] Electrodes 51 and 52 are conductive layers and are formed of a conductive material. Specifically, electrodes 51 and 52 are formed of a metallic material.
[0044] The selector material layer 53 is formed of an insulating material containing additive elements. As the insulating material of the selector material layer 53, silicon oxide containing silicon (Si) and oxygen (O), zirconium oxide containing zirconium (Zr) and oxygen (O), or silicon nitride containing silicon (Si) and nitrogen (N) are used. As additive elements of the selector material layer 53, germanium (Ge), arsenic (As), antimony (Sb), bismuth (Bi), titanium (Ti), tungsten (W), argon (Ar), xenon (Xe), or krypton (Kr) are used.
[0045] Figure 4A , 4B Figures 4C and 4C are schematic diagrams illustrating the first, second, and third examples of the concentration distribution of the added elements, respectively.
[0046] like Figure 4A , 4B As shown in 4C, the added elements are not uniformly distributed, and the concentration of the added elements in the selector material layer 53 has a peak in the interface region 53a, which includes the interface 54 located between the electrode 51 and the selector material layer 53 and the region located near the interface 54.
[0047] The concentration of the added element in the selector material layer 53 decreases from the interface region 53a toward the interface 55 between the electrode 52 and the selector material layer 53. In other words, the concentration of the added element in the selector material layer 53 decreases from the peak concentration position in the interface region 53a toward the interface 55.
[0048] Interface region 53a is, for example, the region from the location of interface 54 to a location at a distance of d / 5 from interface 54, where d is the distance between interface 54 and interface 55. From the viewpoint of reducing the threshold voltage and leakage current of memory cell 30, preferably, the peak concentration location in interface region 53a is close to interface 54, as will be referred to later. Figure 5 As stated above.
[0049] exist Figure 4A In the example, the concentration of the added element in the selector material layer 53 has a peak at the interface 54 between the electrode 51 and the selector material layer 53.
[0050] exist Figure 4B In the example, the concentration of the added element in the selector material layer 53 has a peak in the region near the interface 54.
[0051] exist Figure 4C In the example, the concentration of the added element in the selector material layer 53 has a peak at the interface 54 between the electrode 51 and the selector material layer 53. Figure 4C In the example, when viewing the entire selector 50, the concentration of the added element has a peak in electrode 51, and the concentration of the added element in selector material layer 53 has a peak at interface 54 between electrode 51 and selector material layer 53.
[0052] As described above, in this embodiment, the added element is contained in the selector material layer 53 formed of an insulating material, and the concentration of the added element in the selector material layer 53 has a peak in the interface region 53a, which includes the interface 54 located between the electrode 51 and the selector material layer 53 and the region near the interface 54. With this configuration, in this embodiment, a selector 50 in which both the threshold voltage and leakage current are reduced can be obtained as described below.
[0053] Figure 5 It is a graph showing the relationship between the voltage applied to the memory cell 30, which includes a magnetoresistive element 40 and a selector 50 connected in series with each other, and the current flowing through the memory cell 30.
[0054] exist Figure 5 In the diagram, characteristic (a) is the case where the concentration peak of the added element appears at interface 54. Characteristic (b) is the case where the concentration of the added element is higher than that of characteristic (a), and the concentration peak of the added element appears at interface 54. Characteristic (c) is the case where the distance between interface 54 and interface 55 is d, and the concentration peak of the added element appears at a distance of d / 2 from interface 54. Characteristic (d) is the case where the concentration peak of the added element appears at a distance of d / 4 from interface 54. Characteristic (e) is the case where the concentration peak of the added element appears at a distance of 3d / 4 from interface 54.
[0055] from Figure 5 It can be seen that in characteristic (c), the threshold voltage (the voltage at which the current flowing through the memory cell 30 increases rapidly) is the highest, and the leakage current flowing through the memory cell 30 is also large. In characteristics (d) and (e), both the threshold voltage and leakage current decrease slightly. In characteristics (a) and (b), both the threshold voltage and leakage current decrease significantly.
[0056] As can be seen from the above, when the concentration of the added element in the selector material layer 53 has a peak in the interface region 53a, the threshold voltage and leakage current of the memory cell 30 can be significantly reduced, that is, the threshold voltage and leakage current of the selector 50 can be significantly reduced. The reason for this is believed to be as follows.
[0057] When an additive element is included in the selector material layer 53, traps caused by the additive element are generated in the selector material layer 53. Therefore, the interface region 53a has a relatively high trap density, while the region outside the interface region 53a has a relatively low trap density. In other words, the selector material layer 53 is considered as a series connection of a low-resistance region with a relatively high trap density and a high-resistance region with a relatively low trap density. Therefore, the resistance of the selector material layer 53 at low applied voltages is generally determined by the resistance of the high-resistance region with low trap density (low concentration of the additive element). Thus, the current flowing through the selector 50 is limited by the region with low concentration of the additive element, and leakage current is reduced.
[0058] When a voltage is applied to selector 50, a relatively high voltage is applied to the high-resistivity region where the concentration of the added element is low. Therefore, a high electric field is applied to the high-resistivity region where the concentration of the added element is low, and the switching from the off state to the on state is initiated relatively easily in this region. When the high-resistivity region transitions from the off state to the on state, a voltage is also effectively applied to the low-resistivity region where the concentration of the added element is high. Therefore, the switching from the off state to the on state is performed relatively easily even in the low-resistivity region where the concentration of the added element is high. Therefore, the threshold voltage of selector 50 is considered to decrease.
[0059] As described above, in this embodiment, the threshold voltage and leakage current of selector 50 can be reduced, and a non-volatile memory device with excellent performance can be obtained.
[0060] Figure 6A This is a graph showing the relationship between the threshold voltage and leakage current of a memory cell as the concentration of the added element changes. Here, the leakage current is shown when a half-select voltage (between the selection and non-selection voltages) is applied to the memory cell. Figure 6B It is shown in Figure 6A The graph shows the concentration distribution along the thickness direction of the samples used. The added element is arsenic (As). The peak concentration of sample (a) is 5 × 10⁻⁶. 19 / cm 3 The peak concentration of sample (b) was 2 × 10⁻⁶. 19 / cm 3 .
[0061] like Figure 6A As shown, in both samples (a) and (b), the threshold voltage increases as the leakage current decreases. Therefore, it can be seen that even with changes in the concentration of the added element, the trend of the threshold voltage increasing with decreasing leakage current is not improved.
[0062] Figure 7AThis is a graph showing the relationship between the threshold voltage and leakage current (leakage current when half-select voltage is applied) of a memory cell as the concentration distribution of added elements changes. Figure 7B It is shown in Figure 7A The diagram shows the concentration distribution of the sample used in the thickness direction. The added element is arsenic (As). Sample (a) shows the case where the concentration distribution of the added element is uniform in the thickness direction of the selector material layer 53, sample (b) shows the case where the concentration peak of the added element is located at the center in the thickness direction of the selector material layer 53, and sample (c) shows the case where the concentration peak of the added element is located at a position offset from the center in the thickness direction of the selector material layer 53 towards the electrode 51 or electrode 52.
[0063] like Figure 7A As shown, in sample (c), even with a reduction in leakage current, the increase in threshold voltage is prevented to some extent.
[0064] Figure 8A This is a graph showing the relationship between the threshold voltage and leakage current (leakage current when half-select voltage is applied) of a memory cell as the concentration distribution of the added element changes in the radial direction.
[0065] Figure 8B It is shown in Figure 8A The diagram shows the radial concentration distribution of the samples used. The added element is arsenic (As). Sample (a) shows the case where the concentration distribution of the added element is uniform in the radial direction of the selector material layer 53, sample (b) shows the case where the concentration of the added element increases from the center to the periphery in the radial direction of the selector material layer 53, and sample (c) shows the case where the concentration of the added element decreases from the center to the periphery in the radial direction of the selector material layer 53.
[0066] like Figure 8A As shown, it can be seen that even when the concentration distribution of the added element changes in the radial direction, the relationship between the threshold voltage and the leakage current does not change significantly.
[0067] Figure 9 This is a diagram schematically illustrating a first example of a manufacturing method for selector 50.
[0068] In this manufacturing method, after forming the electrode 51 and the preliminary selector material layer 53p, ion implantation of ions 61, which are added elements, is performed from the side of the preliminary selector material layer 53p. At this time, the accelerating voltage of the ion implantation is adjusted so that a concentration peak of the added element is obtained at or near the interface between the electrode 51 and the preliminary selector material layer 53p. By forming the electrode 52 after ion implantation, a result having such... Figure 4A , 4B Or selector 50 for the concentration distribution of added elements as shown in 4C.
[0069] In the above manufacturing method, electrode 51 is preferably formed from a metallic element selected from cobalt (Co), molybdenum (Mo), ruthenium (Ru), tantalum (Ta), platinum (Pt), and tungsten (W). By using these metallic elements in electrode 51, the average range of ions as added elements can be shortened. Therefore, as... Figure 4A , 4B As shown in 4C, the concentration peak of the added element in the selector material layer 53 can be located at or near the interface 54 between the electrode 51 and the selector material layer 53.
[0070] Figure 10 This is a diagram illustrating a second example of a manufacturing method for selector 50.
[0071] In this manufacturing method, the additive element is pre-included in electrode 51, and the additive element in electrode 51 diffuses into the preliminary selector material layer 53p. Even by using this method, it is possible to form a material with... Figure 4A , 4B Or selector 50 for the concentration distribution of added elements as shown in 4C.
[0072] Figure 11A and 11B This is a diagram schematically illustrating a third example of a method for manufacturing the selector 50.
[0073] In this manufacturing method, such as Figure 11A As shown, a bottom layer 56 containing added elements is formed on electrode 51, and the added elements in the bottom layer 56 diffuse into the preliminary selector material layer 53p. The bottom layer 56 is a conductive layer formed of a conductive material. In this way, the added elements can diffuse from the bottom layer 56 into the preliminary selector material layer 53p. Through this method, as... Figure 11B As shown, a structure was obtained in which the concentration of the added element in the selector material layer 53 has a peak in the interface region 53a, and the interface region 53b includes the interface 54 located between the bottom layer (conductive layer) 56 and the selector material layer 53 and the region near the interface 54.
[0074] Figure 12 The diagram shows a cross-sectional view schematically illustrating a modified configuration of the selector according to this embodiment, and a graph schematically illustrating the concentration distribution of the added elements.
[0075] In this modified example, the concentration of the added element in the selector material layer 53 has a peak in interface region 53a and a peak in interface region 53b. Interface region 53a includes interface 54 and the region near interface 54 located between electrode (conductive layer) 51 and selector material layer 53. Interface region 53b includes interface 55 and the region near interface 55 located between electrode (conductive layer) 52 and selector material layer 53.
[0076] and Figure 9 Similar to the method described in the first example of the manufacturing method, the above structure can be obtained by adjusting the accelerating voltage of ion implantation for adding the element. That is, the accelerating voltage of ion implantation is adjusted so that a concentration peak of the added element is obtained in interface region 53a, and the accelerating voltage of ion implantation is adjusted so that a concentration peak of the added element is obtained in interface region 53b. Alternatively, like... Figure 10 The method described in the second example of the manufacturing method is similar, and the concentration peaks of the added element can be obtained in the interface region 53a and the interface region 53b by diffusing the added element from the electrodes 51 and 52.
[0077] As described above, even if the concentration of the added elements in the selector material layer 53 has peaks in both interface regions 53a and 53b, the threshold voltage and leakage current of the selector 50 can be reduced as in the embodiments described above.
[0078] The above description mainly focuses on the concentration distribution of the added element in the thickness direction of the selector material layer 53. However, the concentration distribution of the added element can also occur in a direction perpendicular to the thickness direction of the selector material layer 53. That is, the concentration of the added element is not uniformly distributed in a plane perpendicular to the direction from the electrode (conductive layer) 51 toward the electrode (conductive layer) 52.
[0079] Figure 13 This illustrates when the concentration of the added element is not uniform in a plane perpendicular to the thickness direction of the selector material layer 53, specifically, with Figure 8B Similar to sample (c), a graph showing the relationship between the applied voltage of memory cell 30 and the current flowing through memory cell 30 as the concentration of the added element decreases radially from the center to the periphery in the selector material layer 53.
[0080] Figure 14 This illustrates that when the concentration of the added element is uniform in a plane perpendicular to the thickness direction of the selector material layer 53, that is, with... Figure 8B Similar to sample (a), a graph showing the relationship between the applied voltage of memory cell 30 and the current flowing through memory cell 30 when the concentration of added elements is uniformly distributed radially in selector material layer 53.
[0081] exist Figure 13 and Figure 14 In the diagram, characteristic (a) is the case where the concentration peak of the added element appears at interface 54. Characteristic (b) is the case where the concentration of the added element is higher than that of characteristic (a), and the concentration peak of the added element appears at interface 54. Characteristic (c) is the case where the distance between interface 54 and interface 55 is d, and the concentration peak of the added element appears at a distance of d / 2 from interface 54. Characteristic (d) is the case where the concentration peak of the added element appears at a distance of d / 4 from interface 54. Characteristic (e) is the case where the concentration peak of the added element appears at a distance of 3d / 4 from interface 54.
[0082] from Figure 13 and Figure 14 It can be seen that when the concentration of the added element is uniform or non-uniform in a plane perpendicular to the thickness direction of the selector material layer 53, or when the concentration of the added element in the thickness direction of the selector material layer 53 has a peak in the interface region 53a, the threshold voltage and leakage current of the memory cell 30 can be effectively reduced. For example, even when the concentration of the added element in the central portion is higher than that in the outer peripheral portion, or the concentration of the added element in the outer peripheral portion is higher than that in the central portion, the threshold voltage and leakage current of the memory cell 30 can still be effectively reduced.
[0083] (Second Embodiment)
[0084] Next, a second embodiment will be described. The basic elements are the same as in the first embodiment, and the descriptions of the elements described in the first embodiment are omitted.
[0085] Figure 15 The diagram illustrates, according to this embodiment, a cross-sectional view of the selector configuration and a graph illustrating, the concentration distribution of the added elements.
[0086] In this embodiment, the selector material layer 53 includes a first layer portion 53S1 disposed on the electrode (conductive layer) 51 side and a second layer portion 53S2 disposed on the electrode (conductive layer) 52 side. That is, the selector material layer 53 includes the first layer portion 53S1 and the second layer portion 53S2 disposed between the electrode 52 and the first layer portion 53S1.
[0087] The concentration of the added element in the first layer 53S1 is higher than that in the second layer 53S2. The concentration of the added element in the first layer 53S1 is substantially uniform, and the concentration of the added element in the second layer 53S2 is also substantially uniform. Ideally, the concentration of the added element would gradually change at the boundary between the first layer 53S1 and the second layer 53S2. However, in reality, the added element may have a concentration gradient due to factors such as diffusion near the boundary between the first layer 53S1 and the second layer 53S2. Therefore, even in this case, the concentration of the added element in the first layer 53S1 is substantially uniform, and the concentration of the added element in the second layer 53S2 is also substantially uniform.
[0088] In this embodiment, a first layer portion 53S1 containing a relatively high concentration of the additive element and a second layer portion 53S2 containing a relatively low concentration of the additive element are formed. Specifically, after depositing the first layer portion 53S1 containing a relatively high concentration of the additive element, the second layer portion 53S2 containing a relatively low concentration of the additive element is deposited. Alternatively, after depositing the second layer portion 53S2 containing a relatively low concentration of the additive element, the first layer portion 53S1 containing a relatively high concentration of the additive element is deposited.
[0089] In this embodiment, similar to the first embodiment, the threshold voltage and leakage current of the selector 50 can also be reduced, and a non-volatile memory device with excellent performance can also be obtained.
[0090] Figure 16 The diagram shows a cross-sectional view schematically illustrating a modified configuration of the selector according to this embodiment, and a graph schematically illustrating the concentration distribution of the added elements.
[0091] In this modified example, the selector material layer 53 further includes a third layer portion 53S3 disposed between the electrode 52 and the second layer portion 53S2. The concentration of the added element in the third layer portion 53S3 is higher than that in the second layer portion 53S2, and the concentration of the added element in the third layer portion 53S3 is substantially uniform. The concentration of the added element in the third layer portion 53S3 may be the same as or different from the concentration of the added element in the first layer portion 53S1.
[0092] In this variation, as in the above embodiments, the threshold voltage and leakage current of selector 50 can be reduced.
[0093] In the first and second embodiments described above, the magnetoresistive effect element 40 is used as a variable resistance storage element, but other variable resistance storage elements in low resistance and high resistance states can also be used.
[0094] Although certain 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 may be embodied in many other forms; furthermore, various omissions, substitutions, and changes may be made to the form 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 that fall within the scope and spirit of this disclosure.
[0095] Label Explanation
[0096] 10: First wiring
[0097] 20: Second wiring
[0098] 30: Memory Basics
[0099] 40: Magnetoresistive element
[0100] 41: Storage layer
[0101] 42: Reference Layer
[0102] 43: Tunnel barrier layer
[0103] 44, 45: Electrodes
[0104] 50: Selector
[0105] 51, 52: Electrodes
[0106] 53: Selector Material Layer
[0107] 53a, 53b: Interface area
[0108] 53p: Preliminary selector material layer
[0109] 53S1: First layer
[0110] 53S2: Second layer
[0111] 53S3: Third layer
[0112] 54, 55: Interface
[0113] 56: Bottom layer
[0114] 61: Ion implantation
Claims
1. A switching element, comprising: First conductive layer; Second conductive layer; as well as A switching material layer, disposed between a first conductive layer and a second conductive layer and formed of an insulating material containing additive elements, includes a first interface region and a second interface region. The first interface region includes a first interface between the first conductive layer and the switching material layer, and the second interface region includes a second interface between the second conductive layer and the switching material layer. The concentration of the added element in the switching material layer has a first peak at a location in the first interface region less than one-fifth of the distance D from the first interface, where D is the distance from the first interface to the second interface. Relative to the first peak, the concentration of the added element in the switching material layer decreases in both the first and second interface regions as the distance from the position of the first peak toward the second interface increases.
2. The switching element according to claim 1, wherein Relative to the first peak, the concentration of the added element in the switching material layer decreases proportionally to the distance from the first interface region toward the second interface region in both the first interface region and the second interface region.
3. The switching element according to claim 1, wherein, The first peak is located at the first interface.
4. The switching element according to claim 1, wherein, The first peak is located in the first interface region at a position far from the first interface.
5. The switching element according to claim 1, wherein The first conductive layer contains elements selected from cobalt (Co), molybdenum (Mo), ruthenium (Ru), tantalum (Ta), platinum (Pt), and tungsten (W).
6. The switching element according to claim 1, wherein In a plane perpendicular to the direction from the first conductive layer toward the second conductive layer, the concentration of the added element in the switching material layer is non-uniform.
7. A storage device, comprising: The switching element according to claim 1; as well as A variable resistance storage element is connected in series with the switching element.
8. The storage device according to claim 7, wherein The variable resistance storage element is a magnetoresistive element.
9. The storage device according to claim 7, further comprising: A first wiring extends in a first direction and connects to one end of a memory cell including the switching element and the variable resistance storage element; as well as A second wiring extends in a second direction intersecting the first direction and connects to the other end of the memory cell.
10. The storage device according to claim 7, wherein, The first peak is located at the first interface.
11. The storage device according to claim 7, wherein, The first peak is located in the first interface region at a position far from the first interface.
12. The storage device according to claim 7, wherein The switching material layer further includes an intermediate region located between the first interface region and the second interface region, and The concentration of the added element in the intermediate region is lower than the concentration of the added element in the first interface region and lower than the concentration of the added element in the second interface region.
13. The storage device according to claim 12, wherein The concentrations of the added elements in the first interface region and the second interface region are substantially uniform.
14. A switching element, comprising: First conductive layer; Second conductive layer; as well as A switching material layer, disposed between the first conductive layer and the second conductive layer, and formed of an insulating material containing additive elements, wherein... The switching material layer includes a first layer portion and a second layer portion disposed between the second conductive layer and the first layer portion. The concentration of the added element in the first layer is higher than the concentration of the added element in the second layer, and The concentration of the added element in the first layer is substantially uniform, and the concentration of the added element in the second layer is substantially uniform.
15. The switching element according to claim 14, wherein The switching material layer further includes a third layer portion disposed between the second conductive layer and the second layer portion, and The concentration of the added element in the third layer is higher than that in the second layer, and the concentration of the added element in the third layer is substantially uniform.
16. The switching element according to claim 14, wherein The insulating material includes any one of the following: a material containing silicon (Si) and oxygen (O), a material containing zirconium (Zr) and oxygen (O), and a material containing silicon (Si) and nitrogen (N).
17. The switching element according to claim 14, wherein The added elements are selected from germanium (Ge), arsenic (As), antimony (Sb), bismuth (Bi), titanium (Ti), tungsten (W), argon (Ar), xenon (Xe), and krypton (Kr).
18. A switching element, comprising: First conductive layer; Second conductive layer; as well as A switching material layer, disposed between a first conductive layer and a second conductive layer and formed of an insulating material containing additive elements, comprises a first interface region, a second interface region, and an intermediate region located between the first interface region and the second interface region. The first interface region includes a first interface between the first conductive layer and the switching material layer, and the second interface region includes a second interface between the second conductive layer and the switching material layer. The concentration of the added element in the switching material layer has a first peak in the first interface region, and The concentration of the added element in the intermediate region is lower than the concentration of the added element in the first interface region and lower than the concentration of the added element in the second interface region.
19. The switching element according to claim 18, wherein The concentration of the added element in the switching material layer has a second peak in the second interface region.
20. The switching element according to claim 19, wherein The concentration of the added element in the switching material layer has a minimum value at the middle position of the intermediate region, and continuously decreases along the intermediate region from the first interface region toward the middle position and along the intermediate region from the second interface region toward the middle position.