Bidirectional threshold switch material and vertical memory device including same

Abstract

Bidirectional threshold switch materials and vertical memory devices including the same are provided. The bidirectional threshold switching material includes germanium (Ge), antimony (Sb), and selenium (Se), where a proportion of Ge in the Ge, Sb, and Se is 10 at% or more and 40 at% or less, a proportion of Sb in the Ge, Sb, and Se is 10 at% or more and 40 at% or less, and a proportion of Se in the Ge, Sb, and Se is 20 at% or more and 80 at% or less, and the bidirectional threshold switching material is doped with indium (In).

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2024-0113705, filed on August 23, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to bidirectional threshold switch materials and vertical (vertical) storage devices including the same. Background Technology

[0004] Chalcogenide-based bidirectional threshold switching elements exhibit electrical reversibility, showing a sharp decrease in resistance above the threshold voltage and a return to a high-resistance state below the threshold voltage. Therefore, they are primarily used as selectors for cross-point memory cells. Recently, selector-only memories (SOMs) have been proposed, where the selector also functions as a memory layer (memory layer) by using bidirectional threshold switching elements with two different threshold voltages depending on polarity.

[0005] Cross-point memory structures have limitations in improving memory integration density because the area of ​​the drive portion increases with increasing cell density. Therefore, although memory devices with vertical structures have been proposed, realizing such devices is difficult because it is challenging to deposit currently known bidirectional threshold switching materials using atomic layer deposition (ALD) methods. Summary of the Invention

[0006] We provide bidirectional threshold switch materials that can be deposited using atomic layer deposition methods and exhibit excellent performance.

[0007] Furthermore, a vertical storage device comprising the bidirectional threshold switch material and possessing excellent performance is provided.

[0008] Other aspects will be set forth in part in the following description, and in part will become apparent from that description, or may be learned through practice of the presented example implementations.

[0009] According to an example embodiment of this disclosure, the bidirectional threshold switch material includes germanium (Ge), antimony (Sb), and selenium (Se), wherein the proportion of Ge in Ge, Sb, and Se is 10 atomic% or greater and 40 atomic% or less, the proportion of Sb in Ge, Sb, and Se is 10 atomic% or greater and 40 atomic% or less, and the proportion of Se in Ge, Sb, and Se is 20 atomic% or greater and 80 atomic% or less, and the bidirectional threshold switch material is doped with indium (In).

[0010] For example, the doping concentration of In in the bidirectional threshold switch material can be greater than 0 atomic% and less than or equal to 10 atomic%, based on the total number of atoms in the bidirectional threshold switch material.

[0011] For example, the doping concentration of In in the bidirectional threshold switch material can be 1 atom% or greater and 10 atom% or less, based on the total number of atoms in the bidirectional threshold switch material.

[0012] For example, the doping concentration of In in the bidirectional threshold switch material may be 1.5 atomic% or greater and 10 atomic% or less, based on the total number of atoms in the bidirectional threshold switch material.

[0013] For example, the doping concentration of In in the bidirectional threshold switch material can be 1 atom% or greater and 5 atom% or less, based on the total number of atoms in the bidirectional threshold switch material.

[0014] For example, the doping concentration of In in the bidirectional threshold switch material may be 1.5 atomic% or greater and 5 atomic% or less, based on the total number of atoms in the bidirectional threshold switch material.

[0015] Furthermore, in Ge, Sb, and Se, the proportion of Ge can be 20 atomic% or more and 35 atomic% or less, the proportion of Sb can be 20 atomic% or more and 35 atomic% or less, and the proportion of Se can be 30 atomic% or more and 60 atomic% or less.

[0016] The concentration of arsenic (As) in the bidirectional threshold switch material can be 0 atoms.

[0017] The bidirectional threshold switch material may be composed of Ge, Sb, Se, and In. Ge, Sb, and Se may constitute the host material, and In may be doped into the host material. The host material may also be referred to as Ge-Sb-Se.

[0018] The threshold voltage drift of the bidirectional threshold switch material can be in the range of 6mV / dec to 7mV / dec.

[0019] According to an example embodiment of this disclosure, a storage device includes: a plurality of word planes extending along a plane including a first direction and a second direction, the plurality of word planes being spaced apart from each other in a third direction perpendicular to the first direction and the second direction; a plurality of vertical bit lines extending in the third direction; and a plurality of bidirectional threshold switch material layers surrounding the respective surfaces of the plurality of vertical bit lines and extending in the third direction, wherein each of the plurality of bidirectional threshold switch material layers comprises germanium (Ge), antimony (Sb), and selenium (Se), wherein the proportion of Ge, Sb, and Se is 10 atomic% or greater and 40 atomic% or less, the proportion of Sb is 10 atomic% or greater and 40 atomic% or less, and the proportion of Se is 20 atomic% or greater and 80 atomic% or less, and each of the plurality of bidirectional threshold switch material layers is doped with indium (In).

[0020] The In doping concentration in each of the plurality of bidirectional threshold switch material layers can be greater than 0 atomic% and less than or equal to 10 atomic%, based on the total number of atoms in each of the plurality of bidirectional threshold switch material layers.

[0021] The doping concentration of In in each of the plurality of bidirectional threshold switch material layers can be 1 atom% or greater and 10 atom% or less, based on the total number of atoms in each of the plurality of bidirectional threshold switch material layers.

[0022] The doping concentration of In in each of the plurality of bidirectional threshold switch material layers may be 1.5 atomic% or greater and 10 atomic% or less, based on the total number of atoms in each of the plurality of bidirectional threshold switch material layers.

[0023] The doping concentration of In in each of the plurality of bidirectional threshold switch material layers can be 1 atom% or greater and 5 atom% or less, based on the total number of atoms in each of the plurality of bidirectional threshold switch material layers.

[0024] The doping concentration of In in each of the plurality of bidirectional threshold switch material layers may be 1.5 atomic% or greater and 5 atomic% or less, based on the total number of atoms in each of the plurality of bidirectional threshold switch material layers.

[0025] In each of the plurality of bidirectional threshold switching material layers, the proportion of Ge in Ge, Sb and Se can be 20 atomic% or more, 35 atomic% or less, the proportion of Sb in Ge, Sb and Se can be 20 atomic% or more, 35 atomic% or less, and the proportion of Se in Ge, Sb and Se can be 30 atomic% or more and 60 atomic% or less.

[0026] The concentration of arsenic (As) in each of the plurality of bidirectional threshold switch material layers may be 0 atomic percent. Each of the plurality of bidirectional threshold switch material layers may consist only of Ge, Sb, Se, and In, without any other elements.

[0027] The threshold voltage drift of each of the multiple bidirectional threshold switch material layers can be in the range of 6mV / dec to 7mV / dec.

[0028] The plurality of bidirectional threshold switch material layers and the plurality of vertical bit lines may pass through the plurality of word planes in the third direction and may be arranged in two dimensions in the first and second directions, and the plurality of word planes may surround the outer surface of the plurality of bidirectional threshold switch material layers.

[0029] The storage device may further include a plurality of dielectric layers surrounding the outer surface of the plurality of bidirectional threshold switch material layers, each of the plurality of dielectric layers being between two adjacent word planes that are adjacent to each other in the third direction of the plurality of word planes. Attached Figure Description

[0030] These and / or other aspects will become clearer and more readily understood from the following description of some exemplary embodiments considered in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 This is a perspective view schematically illustrating the structure of a storage device according to an exemplary embodiment;

[0032] Figure 2 It is shown schematically. Figure 1 A horizontal cross-sectional view of the construction of a storage cell in the storage device described herein;

[0033] Figure 3 It is shown schematically. Figure 1 A vertical cross-sectional view of the construction of a string of storage cells in a storage device as described in the diagram;

[0034] Figure 4 This is a diagram illustrating an example of the voltage-current characteristics of a bidirectional threshold switching material layer in a memory device;

[0035] Figure 5A This is a diagram illustrating an example of a bias voltage (bias voltage) for set and read operations in a storage device according to an exemplary embodiment;

[0036] Figure 5B This is a diagram illustrating an example of bias voltages for reset and read operations in a storage device according to an exemplary embodiment;

[0037] Figure 6This is a diagram illustrating an example of the elemental composition ratio of a bidirectional threshold switch material layer according to an exemplary embodiment;

[0038] Figure 7 This is a graph illustrating an example of how the threshold voltage varies depending on the doping concentration of indium (In) in the bidirectional threshold switch material layer according to an exemplary embodiment.

[0039] Figure 8 This is a graph illustrating an example of the variation in threshold voltage drift depending on the doping concentration of In in the bidirectional threshold switch material layer according to an exemplary embodiment.

[0040] Figure 9 This is a graph illustrating an example of how the leakage current varies depending on the doping concentration of In in the bidirectional threshold switch material layer according to an example embodiment.

[0041] Figure 10 This is a graph illustrating an example of how the storage window varies depending on the doping concentration of In in the bidirectional threshold switch material layer according to an example implementation.

[0042] Figure 11 This is a graph illustrating an example of how the threshold voltage varies depending on the frequency of operation in a bidirectional threshold switch material layer according to the example implementation and comparative examples.

[0043] Figure 12 This is a diagram illustrating an example of how the storage window varies depending on the strength of the write voltage in the bidirectional threshold switch material layer according to the example implementation and comparative examples; and

[0044] Figure 13 It is a schematic concept diagram of a device architecture that can be applied to an electronic device (equipment) according to an example implementation. Detailed Implementation

[0045] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein similar reference numerals always refer to similar elements. In this respect, embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, embodiments are described below only by reference to the accompanying drawings to illustrate aspects. Expressions such as “at least one of,” “one of,” and “any one of” modify the entire list of elements and not individual elements of that list when placed before or after the list of elements. Thus, for example, “at least one of A, B, or C” and “at least one of A, B, and C” both mean A, B, C, or any combination thereof. Similarly, A and / or B means A, B, or A and B.

[0046] Although the terms “identical,” “equal,” or “same” are used in the description of exemplary embodiments, it should be understood that some imprecision may exist. Therefore, when an element is referred to as being identical to another element, it should be understood that one element is identical to the other element within a desired range of manufacturing or operational tolerances (e.g., ±10%).

[0047] When the terms “about,” “substantially,” or “approximately” are used in this specification to refer to numerical values, it is intended that the relevant numerical values ​​include manufacturing or operational tolerances (e.g., ±10%) around the stated numerical values. Similarly, when the terms “about,” “substantially,” or “approximately” are used to refer to geometry, it is intended not to require precision in the geometry, but rather a tolerance for the shape within the scope of this disclosure. Furthermore, regardless of whether a numerical value or shape is modified by “about” or “substantially,” it will be understood that these values ​​and shapes should be interpreted as including manufacturing or operational tolerances (e.g., ±10%) around the stated numerical values ​​or shapes.

[0048] In the following description, a bidirectional threshold switch material and a vertical storage device including the same are described in detail with reference to the accompanying drawings. Throughout the drawings, similar reference numerals denote similar elements, and the dimensions of the components in the drawings may be enlarged for ease of explanation and clarity. Furthermore, since the embodiments described below are examples, other variations can be derived from these embodiments.

[0049] When a constituent element is disposed "above" or "on" another constituent element, the constituent element may include not only elements that are in direct contact with and disposed on the other constituent element, but also elements disposed non-contactly above the other constituent element. As used herein, the singular forms "a" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "comprising" and / or "including" as used herein indicate the presence of a stated feature or component, but do not exclude the presence or addition of one or more other features or components.

[0050] In the context of describing this disclosure, the terms “a” and “the”, and similar expressions, will be interpreted to encompass both the singular and plural. Furthermore, unless otherwise specified herein or otherwise clearly contradicted by the context, the steps of all methods described herein may be performed in any suitable order. This disclosure is not limited to the order of the described steps.

[0051] In addition, terms such as “…part,” “…unit,” “…module,” and “…block” used in the specification may refer to a unit for performing at least one function or operation, and the unit may be embodied in hardware, software, or a combination of hardware and software.

[0052] Furthermore, the connecting lines or connectors shown in the various accompanying figures are intended to represent functional relationships and / or physical or logical connections between various components. It should be noted that many alternative or additional functional relationships, physical connections, or logical connections may exist in actual devices (equipment).

[0053] Any and all instances or language (e.g., "for example") provided herein are intended only to better illustrate the contents of this disclosure and do not limit the scope of this disclosure, unless otherwise stated.

[0054] Figure 1 This is a perspective view schematically illustrating the structure of a storage device 100 according to an exemplary embodiment. Reference Figure 1 The storage device 100 according to an embodiment of the storage device may include: a plurality of word planes (WPs) extending along a plane including a first direction (e.g., the x-axis direction) and a second direction (e.g., the y-axis direction) and spaced apart from each other in a third direction (e.g., the z-axis direction) perpendicular to the first and second directions; a plurality of vertical bit lines VBLs extending upward in the third direction and arranged two-dimensionally in the first and second directions; and a plurality of bidirectional threshold switch material layers OTSs respectively surrounding the surface of the plurality of vertical bit lines VBLs and extending upward in the third direction. The plurality of bidirectional threshold switch material layers OTSs may be arranged two-dimensionally in the first and second directions, just like the plurality of vertical bit lines VBLs.

[0055] Each of the plurality of bidirectional threshold switch material layers (OTS) and the plurality of vertical bit lines (VBL) can be configured to pass through the plurality of word planes (WP) in a third direction. Since the plurality of bidirectional threshold switch material layers (OTS) and the plurality of vertical bit lines (VBL) extend in the vertical direction, therefore... Figure 1 The storage device 100 described herein may be referred to as a vertical storage device and may have relatively high integration and improved storage capacity.

[0056] Figure 2 It is shown schematically. Figure 1 A horizontal cross-sectional view illustrating the construction of a storage cell in the storage device 100 described herein. (Reference) Figure 2 The vertical bit line VBL can have, for example, a cylindrical shape. Furthermore, the bidirectional threshold switch material layer OTS can have a cylindrical shape surrounding the vertical bit line VBL. The bidirectional threshold switch material layer OTS can have a ring shape in a horizontal cross-sectional view. The outer surface of the bidirectional threshold switch material layer OTS can be surrounded by the word plane WP.

[0057] Figure 3 It is shown schematically. Figure 1 A vertical cross-sectional view of the structure of a single memory cell string (MCS) in the memory device 100 described herein. (See reference) Figure 3 The memory cell string (MCS) extending upwards in the third direction may include a vertical bit line (VBL) extending upwards in the third direction, a bidirectional threshold switch material layer (OTS) surrounding the vertical bit line (VBL) and extending upwards in the third direction, word planes (WPs) surrounding the outer surface of the bidirectional threshold switch material layer (OTS) and spaced apart from each other in the third direction, and a plurality of dielectric layers (DLs) surrounding the outer surface of the bidirectional threshold switch material layer (OTS). Each dielectric layer (DL) is disposed between two adjacent word planes (WPs) that are adjacent to each other in the third direction. The dielectric layer (DL) may be a spacer body used to maintain the spacing between two adjacent word planes (WPs).

[0058] A portion of the bidirectional threshold switch material layer OTS and a portion of the vertical bit line VBL, surrounded by a word plane WP on a plane (e.g., the xy plane) in the first and second directions, can form a memory cell MC with its corresponding word plane WP. Therefore, a memory cell string MCS can include multiple memory cells MC spaced apart from each other in a third direction. The storage device 100 can include multiple memory cell strings MCS arranged two-dimensionally in the first and second directions. In this respect, it can be seen that the memory cells MC are arranged three-dimensionally in the first, second, and third directions. Each word plane WP can simultaneously provide a drive voltage or a read voltage to the memory cells MC arranged two-dimensionally on the same plane.

[0059] The word plane WP and the vertical bit line VBL may include conductive materials. The dielectric layer DL may include, for example, insulating dielectric materials such as SiO2, SiN, Al2O3, or HfO2.

[0060] A bidirectional threshold switch material layer (OTS) may include a material having bidirectional threshold switch characteristics. For example, the bidirectional threshold switch material layer OTS may have the characteristic that the threshold voltage can be offset depending on the polarity and intensity of the applied bias voltage. Therefore, the bidirectional threshold switch material layer OTS may have the characteristic of a self-selecting memory that can perform both memory function and selector function using only a single (single) material. For this purpose, the bidirectional threshold switch material layer OTS may include a single material of multi-component chalcogenides.

[0061] Figure 4 This is a diagram illustrating an example of the voltage-current characteristics of the bidirectional threshold switching material layer OTS of the storage device 100. (Reference) Figure 4The bidirectional threshold switching material layer OTS can have either a first state (low Vth state (LVS)) in which the threshold voltage is relatively low and a second state (high Vth state (HVS)) in which the threshold voltage is relatively high. For example, in the first state, the threshold voltage of the bidirectional threshold switching material layer OTS can be a first voltage V1, and in the second state, the threshold voltage of the bidirectional threshold switching material layer OTS can be a second voltage V2 that is greater than the first voltage V1. When the bidirectional threshold switching material layer OTS is in the first state and a voltage less than the first voltage V1 is applied to the bidirectional threshold switching material layer OTS, almost no current flows in the bidirectional threshold switching material layer OTS, and when a voltage greater than the first voltage V1 is applied to the bidirectional threshold switching material layer OTS, the bidirectional threshold switching material layer OTS is turned on, allowing current to flow through the bidirectional threshold switching material layer OTS. Furthermore, when the bidirectional threshold switch material layer OTS is in the second state and a voltage smaller than the second voltage V2 is applied to the bidirectional threshold switch material layer OTS, the current hardly flows in the bidirectional threshold switch material layer OTS, and when a voltage larger than the second voltage V2 is applied to the bidirectional threshold switch material layer OTS, the bidirectional threshold switch material layer OTS is turned on, allowing the current to flow through the bidirectional threshold switch material layer OTS.

[0062] Therefore, the voltage between the first voltage V1 and the second voltage V2 can be selected as the read voltage VR. When the bidirectional threshold switch material layer OTS is in the first state and the read voltage VR is applied to the bidirectional threshold switch material layer OTS, current flows through the bidirectional threshold switch material layer OTS, and in this state, the data value stored in the bidirectional threshold switch material layer OTS can be defined as "1". When the bidirectional threshold switch material layer OTS is in the second state and the read voltage VR is applied to the bidirectional threshold switch material layer OTS, almost no current flows through the bidirectional threshold switch material layer OTS, and in this state, the data value stored in the bidirectional threshold switch material layer OTS can be defined as "0". In other words, when the read voltage VR is applied to the bidirectional threshold switch material layer OTS, the data value stored in the bidirectional threshold switch material layer OTS can be read by measuring the current flowing in the bidirectional threshold switch material layer OTS.

[0063] In the state where the bidirectional threshold switch material layer OTS is in the first state, when a negative (-) bias voltage is applied to the bidirectional threshold switch material layer OTS, the threshold voltage of the bidirectional threshold switch material layer OTS increases, and therefore, the bidirectional threshold switch material layer OTS can be switched to the second state (negative write). For example, when a negative third voltage is applied to the bidirectional threshold switch material layer OTS, the bidirectional threshold switch material layer OTS can be switched to the second state. Such an operation is called a "RESET" operation. Furthermore, in the state where the bidirectional threshold switch material layer OTS is in the second state, when a positive (+) bias voltage greater than the second voltage V2 is applied to the bidirectional threshold switch material layer OTS, the threshold voltage of the bidirectional threshold switch material layer OTS decreases, and therefore, the bidirectional threshold switch material layer OTS can be switched to the first state (positive write). Such an operation is called a "SET" operation.

[0064] Figure 5A This is a diagram illustrating an example of the bias voltage for set and read operations in a storage device 100 according to an exemplary embodiment. (See reference) Figure 5A In the SET operation, a positive bias voltage greater than the second voltage V2 can be applied to the bidirectional threshold switch material layer OTS. This shifts the threshold voltage of the bidirectional threshold switch material layer OTS to the first voltage V1. Then, in the read operation, a positive read voltage VR between the first voltage V1 and the second voltage V2 can be applied to the bidirectional threshold switch material layer OTS. When the read voltage VR is applied to the bidirectional threshold switch material layer OTS, the bidirectional threshold switch material layer OTS can be turned on.

[0065] Figure 5B This is a diagram illustrating an example of the bias voltage for reset and read operations in a storage device 100 according to an exemplary embodiment. (See reference) Figure 5B In a reset operation, a negative bias voltage, such as a negative third voltage V3, can be applied to the bidirectional threshold switch material layer OTS. The absolute value of the third voltage V3 can be approximately the same as or slightly larger or smaller than the second voltage V2. Thus, the threshold voltage of the bidirectional threshold switch material layer OTS can be shifted to a second voltage V2, which is larger than the first voltage V1. Then, in a read operation, a positive read voltage VR, between the first voltage V1 and the second voltage V2, can be applied to the bidirectional threshold switch material layer OTS. When the read voltage VR is applied to the bidirectional threshold switch material layer OTS, the bidirectional threshold switch material layer OTS can be turned off.

[0066] As described above, the bidirectional threshold switching material layer OTS of the memory device 100 according to the exemplary embodiment can have the characteristics of a memory with a variable threshold voltage while having bidirectional threshold switching characteristics. For example, the threshold voltage of the bidirectional threshold switching material layer OTS can be shifted depending on the polarity of the bias voltage applied to the bidirectional threshold switching material layer OTS. Therefore, each memory cell MC of the memory device 100 according to the exemplary embodiment does not need to include a separate selector layer and a separate memory layer, and switching operations and storage operations can be performed with only one bidirectional threshold switching material layer OTS. In this regard, the memory device 100 according to the exemplary embodiment can be a selector-only memory (SOM), especially a vertical SOM (VSOM), because the memory device 100 has a vertical structure in which the memory cells MC are arranged in the vertical direction.

[0067] According to an exemplary embodiment, the bidirectional threshold switching material of the bidirectional threshold switching material layer OTS having the characteristics described above can be a single material comprising a multi-component chalcogenide including germanium (Ge), antimony (Sb), and selenium (Se). The bidirectional threshold switching material layer OTS according to an exemplary embodiment may include Ge-Sb-Se doped with indium (In). Furthermore, the bidirectional threshold switching material layer OTS according to an exemplary embodiment may not include arsenic (As). In other words, the concentration of As in the bidirectional threshold switching material layer OTS according to an exemplary embodiment may be approximately 0 atomic%.

[0068] Figure 6 This is a diagram illustrating an example of the elemental composition ratio of a bidirectional threshold switch material layer (OTS) according to an exemplary embodiment. (Reference) Figure 6 In the Ge-Sb-Se material used as the bidirectional threshold switch material layer OTS, the proportion of Ge can be, for example, about 10 atomic% or more and about 40 atomic% or less, the proportion of Sb can be, for example, about 10 atomic% or more and about 40 atomic% or less, and the proportion of Se can be, for example, about 20 atomic% or more and about 80 atomic% or less. Figure 6 The composition ratio of Ge, Sb, and Se excluding In is shown in the material layer OTS of the bidirectional threshold switch.

[0069] According to the example implementation method, in order to achieve Figures 1 to 3The memory device 100 described herein can form a bidirectional threshold switch material layer OTS by uniformly depositing a bidirectional threshold switch material on the surface of the vertical bit line VBL using an atomic layer deposition (ALD) method. Typically, it is difficult to deposit chalcogenide materials including As using the ALD method because precursors for depositing As-Se atomic layers have not yet been developed. Conversely, the bidirectional threshold switch material layer OTS according to the exemplary embodiment does not include As (i.e., includes 0% As) for deposition using the ALD method, and therefore, the memory device 100 according to the exemplary embodiment can be implemented relatively easily as a VSOM.

[0070] Furthermore, by doping a small amount of In into Ge-Sb-Se, the bidirectional threshold switching material layer OTS according to the example embodiments can have a variety of improved properties, which will be described below.

[0071] Figure 7 This is a graph illustrating an example of how the threshold voltage varies depending on the doping concentration of In in the bidirectional threshold-switching material layer OTS according to an exemplary embodiment. (Reference) Figure 7 As the In doping concentration in the bidirectional threshold switch material layer OTS increases, the threshold voltage of the bidirectional threshold switch material layer OTS can gradually decrease. Figure 7 In this context, the threshold voltage Vth is the threshold voltage under the set state or the first state LVS. Furthermore, in... Figure 7 In this context, the In doping concentration represents the percentage (atomic %) of the number of In atoms relative to the total number of atoms in the bidirectional threshold switch material layer OTS. When the In concentration in the bidirectional threshold switch material layer OTS is approximately 5 atomic %, the threshold voltage of the bidirectional threshold switch material layer OTS can be approximately 1.8 V, which is relatively low. Because the bidirectional threshold switch material layer OTS, including In-doped Ge-Sb-Se, has a relatively low threshold voltage, the memory device 100 can operate (run) at a relatively low voltage, and therefore, the memory device 100 can be applied to a variety of low-power devices.

[0072] exist Figure 7 In this process, the compositions of Ge, Sb, and Se remain constant regardless of the In doping concentration. For example, in... Figure 7 In the examples described above, the proportion of Ge, Sb, and Se can be approximately 27 atomic%, the proportion of Sb can be approximately 24.5 atomic%, and the proportion of Se can be approximately 48.5 atomic%. The compositions of Ge, Sb, and Se described above can be applied to the following descriptions. Figures 8 to 12 The image.

[0073] Figure 8This is a graph illustrating an example of how the threshold voltage drift varies depending on the doping concentration of In in the bidirectional threshold-switching material layer OTS according to an exemplary embodiment. (Reference) Figure 8 As the In doping concentration in the bidirectional threshold switching material layer OTS increases, the threshold voltage drift of the bidirectional threshold switching material layer OTS can gradually decrease. For example, when the In concentration in the bidirectional threshold switching material layer OTS is about 3 atomic% or greater, the threshold voltage drift of the bidirectional threshold switching material layer OTS can be about 10 mV / dec or less, or in the range of about 6 mV / dec to about 7 mV / dec. Therefore, the level of change in the threshold voltage of the bidirectional threshold switching material layer OTS can be relatively low as time passes or the frequency of operation increases. Therefore, the memory device 100 including the bidirectional threshold switching material layer OTS can have relatively stable operating characteristics.

[0074] Figure 9 This is a graph illustrating an example of how the leakage current varies depending on the doping concentration of In in the bidirectional threshold switch material layer OTS according to an exemplary embodiment. (Reference) Figure 9 As the In doping concentration in the bidirectional threshold switch material layer OTS increases, the leakage current (IL) of the bidirectional threshold switch material layer OTS also increases. off The leakage current (IL) of the bidirectional threshold switch material layer OTS increases slightly. However, overall, the leakage current (IL) of the OTS increases slightly. off The current can remain relatively low, from about 12 nA to about 21 nA. Therefore, the memory device 100, including the bidirectional threshold switch material layer OTS, can have relatively low power consumption and relatively stable operating characteristics. Although not explicitly stated... Figure 9 As shown in the figure, however, the doping concentration of In in the bidirectional threshold switch material layer OTS can be limited to about 10 atomic percent or less to reduce or prevent excessive increase in leakage current.

[0075] Figure 10 This is a diagram illustrating an example of how the memory window varies depending on the doping concentration of In in a bidirectional threshold-switching material layer OTS according to an exemplary embodiment. The memory window is the difference between two threshold voltages of the bidirectional threshold-switching material layer OTS. For example, when the threshold voltage of the bidirectional threshold-switching material layer OTS is a first voltage V1 in a first state and a second voltage V2 in a second state, the memory window ΔVth can be (V2-V1). As the memory window ΔVth increases, the difference between the first and second states becomes more pronounced, and therefore, the operational reliability of the memory device 100 can be improved. (Reference) Figure 10Until the In doping concentration in the bidirectional threshold switch material layer OTS is approximately 3 atomic%, the storage window ΔVth can gradually increase as the In doping concentration increases. When the In doping concentration exceeds approximately 3 atomic%, the storage window ΔVth can gradually decrease as the In doping concentration increases. For example, when the In doping concentration in the bidirectional threshold switch material layer OTS is approximately 3 atomic%, the storage window ΔVth can have a maximum value of approximately 2.3V or greater, for example, approximately 2.34V.

[0076] Figure 11 This is a graph illustrating an example of the variation of the threshold voltage depending on the frequency of operation in a bidirectional threshold switch material layer OTS according to the example implementation and comparative examples, and Figure 12 This is a graph illustrating an example of how the storage window varies depending on the strength of the write voltage in the bidirectional threshold switch material layer OTS, according to the example implementation and comparative examples. Figure 11 and 12 A comparison is shown between a comparative example without In doping and an example embodiment with In doping. In the example embodiment with In doping, the In doping concentration in the bidirectional threshold switch material layer OTS is about 1.5 atomic%, while in the comparative example without In doping, the In doping concentration in the bidirectional threshold switch material layer OTS is about 0 atomic%. Furthermore, in both the example embodiment and the comparative example, the proportion of Ge, Sb, and Se can be about 27 atomic%, the proportion of Sb can be about 24.5 atomic%, and the proportion of Se can be about 48.5 atomic%.

[0077] exist Figure 11 In the diagram, the figures indicated by circles (●) represent exemplary embodiments in which In is doped at a concentration of approximately 1.5 atomic percent, and the figures indicated by squares (■) represent comparative examples without In doping. Reference Figure 11 In the example embodiment where In is doped at a concentration of approximately 1.5 atomic%, the threshold voltage is lower than that of the comparative embodiment without In doping. Furthermore, compared to the comparative embodiment without In doping, the variation in the threshold voltage depending on the operating frequency is smaller in the example embodiment where In is doped at a concentration of approximately 1.5 atomic%. For example, in the example embodiment where In is doped at a concentration of approximately 1.5 atomic%, the threshold voltage remains almost unchanged even after 1G of operation. Figure 11 In this context, the threshold voltage Vth is the threshold voltage under the set state or the first state LVS.

[0078] exist Figure 12In the diagram, the figure represented by the inverted triangle (▼) represents the threshold voltage in the set state or first state LVS in an example embodiment in which In is doped at a concentration of approximately 1.5 atomic percent, and the figure represented by the triangle (▲) represents the threshold voltage in the reset state or second state HVS in an example embodiment in which In is doped at a concentration of approximately 1.5 atomic percent. Furthermore, in Figure 12 In the diagram, the graphs indicated by circles (●) represent the threshold voltage of the undoped comparative example in the set state or first state LVS, and the graphs indicated by squares (■) represent the threshold voltage of the undoped comparative example in the reset state or second state HVS. Reference Figure 12 Regardless of the strength of the write voltage used to put the bidirectional threshold switch material layer (OTS) into the set state, the threshold voltage of the example embodiment doped with In at a concentration of approximately 1.5 atomic percent can be lower than that of the comparative embodiment without In doping. Furthermore, as the write voltage increases, the memory window of the example embodiment doped with In at a concentration of approximately 1.5 atomic percent can be further increased to a larger value compared to the memory window of the comparative embodiment without In doping.

[0079] Considering reference Figures 7 to 12 The described results indicate that the In doping concentration in the bidirectional threshold switch material layer OTS, according to exemplary embodiments, can be greater than 0 atomic% and less than or equal to about 10 atomic%. According to some exemplary embodiments, the In doping concentration in the bidirectional threshold switch material layer OTS can be about 1 atomic% or greater and about 10 atomic% or less, about 1.5 atomic% or greater and about 10 atomic% or less, about 3 atomic% or greater and about 10 atomic% or less, about 1 atomic% or greater and about 5 atomic% or less, about 1.5 atomic% or greater and about 5 atomic% or less, or about 3 atomic% or greater and about 5 atomic% or less. Furthermore, in Ge, Sb, and Se, the proportion of Ge can be about 20 atomic% or greater and about 35 atomic% or less, the proportion of Sb can be about 20 atomic% or greater and about 35 atomic% or less, and the proportion of Se can be about 30 atomic% or greater and about 60 atomic% or less.

[0080] When voltage V is applied to Figures 1 to 3When the bidirectional threshold switch material layer OTS of any selected memory cell (hereinafter referred to as "selected memory cell") in the three-dimensional arrangement of memory cells MC of the memory device 100 described herein is applied, a voltage V can be provided to the word plane WP of the selected memory cell and a voltage V / 2 can be provided to the other word planes WP. Furthermore, a voltage of 0V can be provided to the vertical bit line VBL of the selected memory cell, and a voltage V / 2 can be provided to the other vertical bit lines VBL. Thus, the potential difference between the word plane WP and the vertical bit line VBL of the selected memory cell is equal to V. Conversely, the potential difference between the word plane WP to which voltage V / 2 is applied and the vertical bit line VBL to which voltage V / 2 is applied is equal to 0V. Therefore, no voltage is applied to the unselected memory cells arranged between the word plane WP and the vertical bit line VBL that are not connected to the selected memory cell. A voltage V / 2 can be applied to the bidirectional threshold switch material layer OTS of a memory cell (hereinafter referred to as a "half-selected memory cell") connected to either the word plane WP of the selected memory cell MC or the vertical bit line VBL of the selected memory cell MC, on which the bidirectional threshold switch material layer OTS is connected. The bidirectional threshold switch material layer OTS according to an exemplary embodiment is a self-selecting device having the threshold voltage described above. Therefore, even when a voltage V / 2 is applied to the bidirectional threshold switch material layer OTS of a half-selected memory cell adjacent to the selected memory cell, the bidirectional threshold switch material layer OTS of the half-selected memory cell may not be turned on, and thus, leakage current may be almost non-existent.

[0081] The storage device 100 described above can be used to store data in various electronic devices. Figure 13 This is a schematic conceptual diagram of a device architecture applicable to an electronic device 200 implemented according to an example. (Reference) Figure 13 The electronic device 200 may include main memory 210, auxiliary memory 220, central processing unit (CPU) 230, and input / output devices 240. CPU 230 may include cache memory 231, arithmetic logic unit (ALU) 232, and control unit 233. Cache memory 231 may include static random access memory (SRAM). Main memory 210 may include DRAM devices, and auxiliary memory 220 may include storage device 100 according to an exemplary embodiment. Cache memory 231, main memory 210, and auxiliary memory 220 may all include storage device 100 according to an exemplary embodiment. In some cases, the electronic device 200 may be implemented with computing unit devices and storage unit devices adjacent to each other on a single chip, without the distinction of sub-units described above.

[0082] Any functional blocks shown in the accompanying drawings and described above can be implemented as processing circuitry, such as hardware including logic circuitry, hardware / software combinations such as a processor executing software, or combinations thereof. For example, processing circuitry may more specifically include, but is not limited to, central processing units (CPUs), arithmetic logic units (ALUs), digital signal processors, microcomputers, field-programmable gate arrays (FPGAs), system-on-a-chip (SoCs), programmable logic units, microprocessors, application-specific integrated circuits (ASICs), etc.

[0083] It should be understood that the vertical storage devices including bidirectional threshold switching materials described herein are to be considered in a descriptive sense only and are not intended for limiting purposes. The descriptions of features or aspects in the various exemplary embodiments should typically be considered applicable to other similar features or aspects in other exemplary embodiments. Although one or more exemplary embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope defined by the appended claims.

Claims

1. Bidirectional threshold switching materials, including germanium (Ge), antimony (Sb), and selenium (Se), among which... The proportion of Ge in Ge, Sb, and Se is 10 atomic% or greater and 40 atomic% or less. The proportion of Sb in Ge, Sb, and Se is 10 atomic% or greater and 40 atomic% or less. The proportion of Se in Ge, Sb, and Se is 20 atomic% or greater and 80 atomic% or less, and The bidirectional threshold switch material is doped with indium (In).

2. The bidirectional threshold switch material according to claim 1, wherein the doping concentration of In in the bidirectional threshold switch material is greater than 0 atomic% and less than or equal to 10 atomic%, based on the total number of atoms in the bidirectional threshold switch material.

3. The bidirectional threshold switch material according to claim 1, wherein the doping concentration of In in the bidirectional threshold switch material is 1 atom% or greater and 10 atom% or less, based on the total number of atoms in the bidirectional threshold switch material.

4. The bidirectional threshold switch material according to claim 1, wherein the doping concentration of In in the bidirectional threshold switch material is 1.5 atomic% or greater and 10 atomic% or less, based on the total number of atoms in the bidirectional threshold switch material.

5. The bidirectional threshold switch material according to claim 1, wherein the doping concentration of In in the bidirectional threshold switch material is 1 atom% or greater and 5 atom% or less, based on the total number of atoms in the bidirectional threshold switch material.

6. The bidirectional threshold switch material according to claim 1, wherein the doping concentration of In in the bidirectional threshold switch material is 1.5 atomic% or greater and 5 atomic% or less, based on the total number of atoms in the bidirectional threshold switch material.

7. The bidirectional threshold switch material according to claim 1, wherein... The proportion of Ge in Ge, Sb, and Se is 20 atomic% or greater and 35 atomic% or less. The proportion of Sb in Ge, Sb, and Se is 20 atomic% or greater and 35 atomic% or less, and The proportion of Se in Ge, Sb, and Se is 30 atomic% or greater and 60 atomic% or less.

8. The bidirectional threshold switch material according to claim 1, wherein the concentration of arsenic (As) in the bidirectional threshold switch material is 0 atoms.

9. The bidirectional threshold switch material according to claim 1, wherein the threshold voltage drift of the bidirectional threshold switch material is in the range of 6mV / dec to 7mV / dec.

10. Storage devices, including: A plurality of word planes extending along a plane including a first direction and a second direction, the plurality of word planes being spaced apart from each other in a third direction perpendicular to the first direction and the second direction; Multiple vertical bit lines extending upwards from the third party; and Multiple bidirectional threshold switch material layers surrounding the surfaces of the plurality of vertical bit lines and extending upward from the third party. Each of the plurality of bidirectional threshold switch material layers comprises a bidirectional threshold switch material according to any one of claims 1 to 9.

11. The storage device according to claim 10, wherein The plurality of bidirectional threshold switch material layers and the plurality of vertical bit lines pass through the plurality of word planes in the third direction and are arranged in two dimensions in the first and second directions. The plurality of word planes surround the outer surface of the plurality of bidirectional threshold switch material layers.

12. The storage device of claim 10, further comprising: Multiple dielectric layers surround the outer surface of the multiple bidirectional threshold switch material layers, each of the multiple dielectric layers being between two adjacent word planes that are adjacent to each other in the third direction of the multiple word planes.

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