Threshold switch material, threshold switch device and preparation method thereof

Abstract

The invention provides a threshold switch material, a threshold switch device and a preparation method thereof. The chemical general formula of the threshold switch material is (InxTe100-x) 100-z (As100-ySey) z, x is the atomic percent of an element In in the element In and the element Te, y is the atomic percent of an element Se in the element As and the element Se, z is the atomic percent of the element As and the element Se in the threshold switch material, 30 < = x < = 50, 50 < = y < = 70, and 50 < = z < = 90. According to the threshold switch material provided by the invention, the threshold voltage drift can be reduced, so that the stability of a threshold switch device is improved.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of semiconductors, and more specifically, to a threshold switching material, a threshold switching device, and a method for preparing the same. Background Art

[0002] With the advent of the big data era dominated by technologies such as artificial intelligence, Internet of Things, and big data, people's requirements for information storage are getting higher and higher. Memory is an important device for realizing information storage and occupies an important position in the semiconductor market. With the rapid development of the semiconductor industry, the semiconductor process level has also been greatly improved, and many new types of memories have emerged. Among these new types of memories, phase change memory (PCM) has the advantages of fast read and write speed, low operating power consumption, good cycle life, good vibration and radiation resistance, etc. In order to obtain better comprehensive performance, PCM not only requires excellent storage units, but also requires a selector tube that matches the performance of the storage unit to realize a three-dimensional cross-point (3D Xpoint) storage chip with a unit structure of one selector-one resistor (1S1R) and stackable, which is used for persistent memory (PMem), storage class memory (SCM), etc.

[0003] Among them, a threshold switching device composed of a threshold switching material can be used as the selector tube of PCM. However, the existing threshold switching materials have a large threshold voltage drift, making it difficult for the threshold switching device to meet the requirements of high-performance PCM. Therefore, how to reduce the threshold voltage drift of the threshold switching material to improve the stability of the threshold switching device has become an urgent technical problem to be solved. Summary of the Invention

[0004] Embodiments of the present application provide a threshold switching material, a threshold switching device, and a method for preparing the same, which can reduce the threshold voltage drift of the threshold switching material, thereby improving the stability of the threshold switching device.

[0005] In a first aspect, a threshold switching material is provided. The chemical general formula of the threshold switching material is (In x Te 100-x ) 100-z (As 100-y Se y ) z, where x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, and 30 ≤ x ≤ 50, 50 ≤ y ≤ 70, 50 ≤ z ≤ 90.

[0006] It should be understood that (In x Te 100-x ) 100-z (As 100-y Se y ) z is an amorphous compound.

[0007] Optionally, the atomic ratio of element In to element Te is close to 2:3.

[0008] Optionally, the atomic ratio of element As to element Se is close to 2:3.

[0009] According to the technical solution provided by this application, elements In and Te have good electrical conductivity, which can enable the threshold switching material to have a lower threshold voltage, so that the threshold switching device prepared from this threshold switching material has a higher on-off ratio and response speed, and provides higher thermal stability, which is conducive to the preparation of the threshold switching device; on the other hand, elements As and Se can stabilize the network structure of the amorphous compound, so that the threshold switching material has a lower threshold voltage drift coefficient, so that the threshold switching device prepared from this threshold switching material has higher stability. In summary, the threshold switching material provided by the embodiments of this application can reduce the threshold voltage drift and improve the working stability of the threshold switching device on the basis of ensuring the working performance of the threshold switching device.

[0010] Combined with the first aspect, in some implementation manners of the first aspect, the average coordination number of the threshold switching material is greater than or equal to 2.4 and less than or equal to 2.5.

[0011] Optionally, the average coordination number of the threshold switching material is close to 2.45.

[0012] Optionally, the average coordination number of the threshold switching material satisfies the following formula:

[0013]

[0014] where MCN is the average coordination number of the threshold switching material, x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, CN In is the coordination number of In atoms in the threshold switching material, CN Teis the coordination number of Te atoms in the threshold switching material, CN As is the coordination number of As atoms in the threshold switching material, CN Se is the coordination number of Se atoms in the threshold switching material.

[0015] Optionally, the coordination number of In atoms in the threshold switching material can be 5, the coordination number of Te atoms in the threshold switching material can be 2, the coordination number of As atoms in the threshold switching material can be 3, and the coordination number of Se atoms in the threshold switching material can be 2.

[0016] According to the above technical solution, when the average coordination number is close to 2.45, it is the most stable state in the amorphous network structure of the threshold switching material, thereby further improving the stability of the threshold switching device prepared from the threshold switching material.

[0017] Combined with the first aspect, in some implementation manners of the first aspect, the chemical general formula of the threshold switching material is (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 .

[0018] Combined with the first aspect, in some implementation manners of the first aspect, the chemical general formula of the threshold switching material is (In 38 Te 62 ) 44 (As 41 Se 59 ) 56 .

[0019] In a second aspect, a threshold switching device is provided, including a lower electrode layer; a threshold switching material layer located above the lower electrode layer; an upper electrode layer located above the threshold switching material layer; wherein, the threshold switching material layer includes a threshold switching material, and the chemical general formula of the threshold switching material is (In x Te 100-x ) 100-z (As 100-y Se y ) z , where x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, and 30 ≤ x ≤ 50, 50 ≤ y ≤ 70, 50 ≤ z ≤ 90.

[0020] It should be understood that (In x Te 100-x ) 100-z (As 100-ySe y ) z is an amorphous compound.

[0021] It should be understood that the above description is only an illustration of the relative positions among the lower electrode layer, the threshold switching material layer, and the upper electrode layer in the threshold switching device, and does not limit the connection relationship among the layers. For example, the upper electrode layer is located above the threshold switching material layer, which may be that the upper electrode layer is directly disposed on the upper surface of the threshold switching material layer; it is also possible that other layers are disposed above the threshold switching material layer, such as a buffer layer, a phase change material layer, etc., and the upper electrode layer is disposed above the above other layers. The present application does not make specific limitations thereto.

[0022] Optionally, the atomic ratio of element In to element Te is close to 2:3.

[0023] Optionally, the atomic ratio of element As to element Se is close to 2:3.

[0024] Combined with the second aspect, in some implementation manners of the second aspect, the average coordination number of the threshold switching material is greater than or equal to 2.4 and less than or equal to 2.5.

[0025] Optionally, the average coordination number of the threshold switching material is close to 2.45.

[0026] Optionally, the average coordination number of the threshold switching material satisfies the following formula:

[0027]

[0028] where MCN is the average coordination number of the threshold switching material, x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, CN In is the coordination number of In atoms in the threshold switching material, CN Te is the coordination number of Te atoms in the threshold switching material, CN As is the coordination number of As atoms in the threshold switching material, CN Se is the coordination number of Se atoms in the threshold switching material.

[0029] Optionally, the coordination number of In atoms in the threshold switching material can be 5, the coordination number of Te atoms in the threshold switching material can be 2, the coordination number of As atoms in the threshold switching material can be 3, and the coordination number of Se atoms in the threshold switching material can be 2.

[0030] Combined with the second aspect, in some implementation manners of the second aspect, the chemical general formula of the threshold switching material is (In 36 Te64 ) 14 (As 35 Se 65 ) 86 。

[0031] In combination with the second aspect, in some implementations of the second aspect, the chemical general formula of the threshold switching material is (In 38 Te 62 ) 44 (As 41 Se 59 ) 56 。

[0032] In combination with the second aspect, in some implementations of the second aspect, the threshold switching device further includes an isolation material layer, and the isolation material layer covers the side surfaces of the overall structure composed of the lower electrode layer, the threshold switching material layer, and the upper electrode layer.

[0033] It should be understood that the side surfaces of the overall structure may refer to all the surfaces of the overall structure except the lower surface of the lower electrode layer and the upper surface of the upper electrode layer.

[0034] Optionally, the threshold switching device may include a plurality of overall structures composed of a lower electrode layer, a threshold switching material layer, and an upper electrode layer, and the isolation material layer may cover the side surfaces of each overall structure.

[0035] In combination with the second aspect, in some implementations of the second aspect, the isolation material of the isolation material layer includes Si 3 N 4 and / or SiO 2 。

[0036] In combination with the second aspect, in some implementations of the second aspect, the thickness of the threshold switching material layer is greater than or equal to 5 nm and less than or equal to 50 nm.

[0037] Optionally, the thickness of the threshold switching material layer may be equal to 20 nm.

[0038] In combination with the second aspect, in some implementations of the second aspect, the material of the lower electrode layer includes at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0039] In combination with the second aspect, in some implementations of the second aspect, the material of the upper electrode layer includes at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0040] In a third aspect, a method for fabricating a threshold switching device is provided, including: forming a lower electrode layer over a substrate; forming a threshold switching material layer over the lower electrode layer; forming an upper electrode layer over the threshold switching material layer; wherein, the threshold switching material layer includes a threshold switching material, and the chemical formula of the threshold switching material is (In x Te 100-x ) 100-z (As 100-y Se y ) z , where x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, and 30 ≤ x ≤ 50, 50 ≤ y ≤ 70, 50 ≤ z ≤ 90.

[0041] It should be understood that (In x Te 100-x ) 100-z (As 100-y Se y ) z is an amorphous compound.

[0042] Optionally, the atomic ratio of element In to element Te is close to 2:3.

[0043] Optionally, the atomic ratio of element As to element Se is close to 2:3.

[0044] In combination with the third aspect, in some implementations of the third aspect, the average coordination number of the threshold switching material is greater than or equal to 2.4 and less than or equal to 2.5.

[0045] Optionally, the average coordination number of the threshold switching material is close to 2.45.

[0046] Optionally, the average coordination number of the threshold switching material satisfies the following formula:

[0047]

[0048] where MCN is the average coordination number of the threshold switching material, x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, CN In is the coordination number of In atoms in the threshold switching material, CN Te is the coordination number of Te atoms in the threshold switching material, CN As is the coordination number of As atoms in the threshold switching material, and CN Se is the coordination number of Se atoms in the threshold switching material.

[0049] Optionally, the coordination number of In atoms in the threshold switching material can be 5, the coordination number of Te atoms in the threshold switching material can be 2, the coordination number of As atoms in the threshold switching material can be 3, and the coordination number of Se atoms in the threshold switching material can be 2.

[0050] Combined with the third aspect, in some implementations of the third aspect, the chemical general formula of the threshold switching material is (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 .

[0051] Combined with the third aspect, in some implementations of the third aspect, the chemical general formula of the threshold switching material is (In 38 Te 62 ) 44 (As 41 Se 59 ) 56 .

[0052] Combined with the third aspect, in some implementations of the third aspect, the method further includes: etching partial positions of the lower electrode layer, the threshold switching material layer, and the upper electrode layer to form a columnar structure composed of the lower electrode layer, the threshold switching material layer, and the upper electrode layer; depositing an isolation material at the etched partial positions to form an isolation material layer.

[0053] Optionally, the columnar structure can be a cuboid structure.

[0054] Optionally, the columnar structure can be a cylindrical structure, and the diameter of the cylindrical structure is 200 nm.

[0055] Optionally, multiple columnar structures can be formed after etching, and the spacing between each columnar structure can be 200 nm.

[0056] Combined with the third aspect, in some implementations of the third aspect, the isolation material includes Si 3 N 4 and / or SiO 2 .

[0057] Combined with the third aspect, in some implementations of the third aspect, the thickness of the threshold switching material layer is greater than or equal to 5 nm and less than or equal to 50 nm.

[0058] Optionally, the thickness of the threshold switching material layer can be equal to 20 nm.

[0059] In connection with the third aspect, in some implementations of the third aspect, the material of the lower electrode layer includes at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0060] In connection with the third aspect, in some implementations of the third aspect, the material of the upper electrode layer includes at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0061] In a fourth aspect, there is provided a memory chip, including a memory cell and a threshold switching device as in the second aspect or any possible implementation of the second aspect.

[0062] In a fifth aspect, there is provided a memory, including the memory chip as in the fourth aspect.

[0063] Optionally, the memory may further include a controller for performing read and write operations on the data in the memory chip.

[0064] In a sixth aspect, there is provided a computing device, including the memory chip as in the fourth aspect, or including the memory as in the fifth aspect.

[0065] Optionally, the computing device may be including but not limited to a desktop computer, a laptop computer, a smart phone, a tablet computer, a personal digital assistant (PDA), a wearable device, a smart speaker, a television, a drone, a vehicle, an in-vehicle device (such as a car head unit, an in-vehicle computer, an in-vehicle chip, etc.) or a robot, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a schematic structural block diagram of a memory provided by an embodiment of the present application.

[0067] Figure 2 is a schematic structural diagram of a memory chip provided by an embodiment of the present application.

[0068] Figure 3 is a schematic structural diagram of a threshold switching device provided by an embodiment of the present application.

[0069] Figure 4 is an electrical performance test diagram of a threshold switching device provided by an embodiment of the present application.

[0070] Figure 5 is an electrical performance test diagram of another threshold switching device provided by an embodiment of the present application.

[0071] Figure 6It is a test chart of the electrical performance of another threshold switch device provided by an embodiment of the present application.

[0072] Figure 7 It is a schematic flowchart of a method for preparing a threshold switch device provided by an embodiment of the present application.

[0073] Figure 8 It is a schematic structural diagram of a threshold switch device provided by an embodiment of the present application.

[0074] Figure 9 It is a schematic structural diagram of a threshold switch device provided by an embodiment of the present application.

[0075] Figure 10 It is a schematic structural diagram of a threshold switch device provided by an embodiment of the present application. Detailed implementation manners

[0076] Next, the technical solutions in the present application will be described with reference to the accompanying drawings.

[0077] The present application will present various aspects, embodiments or features around a system including multiple devices, components, modules, etc. It should be understood and clear that each system may include additional devices, components, modules, etc., and / or may not include all the devices, components, modules, etc. discussed in conjunction with the accompanying drawings. In addition, combinations of these solutions can also be used.

[0078] In addition, in the embodiments of the present application, words such as "exemplary" and "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" in the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly speaking, the use of the word "exemplary" is intended to present concepts in a specific way.

[0079] In the embodiments of the present application, "corresponding" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference is not emphasized, the meanings they express are the same.

[0080] The system architecture and business scenarios described in the embodiments of the present application are for more clearly illustrating the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those of ordinary skill in the art know that with the evolution of the system architecture and the emergence of new business scenarios, the technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems.

[0081] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc., which appear in different places in this specification, are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized.

[0082] In this application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may mean: including the case where A exists alone, the case where A and B exist simultaneously, and the case where B exists alone, where A and B may be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (item)" or similar expressions thereof refer to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b, or c may mean: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, c may be single or multiple.

[0083] With the advent of the big data era dominated by technologies such as artificial intelligence, Internet of Things, and big data, people's requirements for information storage are getting higher and higher. Memory is an important device for realizing information storage and occupies an important position in the semiconductor market. With the rapid development of the semiconductor industry, the semiconductor process level has also been greatly improved, and many new types of memories have emerged. Among the many new types of memories, phase change memory (PCM) has the advantages of fast read and write speed, low operating power consumption, good cycle life, good shock and radiation resistance, etc.

[0084] Figure 1 is a schematic structural block diagram of a memory 100 to which the embodiments of the present application can be applied. As Figure 1As shown, the memory 100 may include a controller 110 and a memory chip 120. Optionally, the memory 100 may be a PCM. Among them, the memory chip 120 may include a plurality of memory cells, and the controller 110 may communicate with each memory cell in the memory chip 120. The controller 110 may include a row decoder, an amplifier, a column decoder, and other control circuits. Thus, the controller 110 may control the read and write operations and other operations of each memory cell. For example, the controller 110 may write data into each memory cell; for another example, the controller 110 may read data from each memory cell.

[0085] In the memory chip 120, it is usually necessary to use a selector tube with switching performance to select the memory cells. The following takes Figure 2 the shown three-dimensional cross point (3D Xpoint) memory chip 121 as an example to introduce the structure of the memory chip exemplarily.

[0086] Figure 2 is a schematic structural diagram of a part of a memory chip 121 to which the embodiments of the present application can be applied. As Figure 2 shown, the memory chip 121 may include at least one selector tube 10 and at least one phase change memory cell 20. Optionally, at least one selector tube 10 in the selector tube array may be connected in series with at least one phase change memory cell 20 in the phase change memory cell array in one-to-one correspondence, so as to form a one-selector-one-resistor (1S1R) unit structure.

[0087] It should be understood that Figure 2 the shown memory chip 121 is only an example. In other possible implementation manners, the embodiments of the present application may also be applied to memory chips with other structures, and the present application does not make specific limitations on the structure of the memory chip.

[0088] Among the devices that select a gating tube or a gating tube array in many storage chips that can be used as PCMs, a two-way threshold switch (OTS) device using a chalcogenide thin film as a medium is a typical threshold switch device. The OTS device mainly includes upper and lower electrode materials, a chalcogenide thin film material with volatile threshold transition characteristics, and an insulating dielectric material for protecting the chalcogenide thin film material from oxidation. The working principle of the OTS device is to use an electrical signal to control the switch of the device, that is, when the applied electrical signal meets certain conditions, the threshold switch material changes from a high-resistance state to a low-resistance state, and the OTS device is in an on state. Different types of pulse signals can be applied to the phase change memory cell to make the phase change memory material reversibly change between high and low resistances to achieve the storage of logic "0" and "1"; when the electrical signal applied to the OTS device is lower than a certain specific value, the threshold switch material changes from a low-resistance state to a high-resistance state, and the threshold switch device is in an off state. At this time, the leakage current of other cells will not affect the resistance state of this storage cell, ensuring the reliability of information storage.

[0089] Typical threshold switch materials can be, for example, Ge-Se alloy materials, Ge-As-Se alloy materials, etc. However, the threshold voltage of existing threshold switch materials will shift greatly over time, resulting in a change in the programming voltage state in the memory of the threshold switch device, and the read-write window cannot be maintained, leading to device failure and poor reliability.

[0090] In view of this, the embodiments of the present application provide a threshold switch material that can reduce the threshold voltage drift of the threshold switch material, thereby improving the stability of the threshold switch device prepared using this threshold switch material.

[0091] Specifically, the chemical general formula of the threshold switch material provided by the embodiments of the present application is (In x Te 100-x ) 100-z (As 100- y Se y ) z , where x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switch material, and 30≤x≤50, 50≤y≤70, 50≤z≤90. As an example, (In x Te 100-x ) 100-z (As 100-y Se y ) z can be (In 36 Te 64 )14 (As 35 Se 65 ) 86 、(In 35 Te 65 ) 24 (As 36 Se 64 ) 76 、(In 38 Te 62 ) 44 (As 41 Se 59 ) 56 etc., and the present application does not make specific limitations thereon.

[0092] It should be understood that (In x Te 100-x ) 100-z (As 100-y Se y ) z is an amorphous compound.

[0093] Optionally, the atomic ratio of element In to element Te is close to 2:3.

[0094] Optionally, the atomic ratio of element As to element Se is close to 2:3.

[0095] In the above threshold switching material (In x Te 100-x ) 100-z (As 100-y Se y ) z elements In and Te can provide good electrical conductivity for the material. Therefore, the smaller the z value, that is, the higher the contents of elements In and Te, the lower the threshold voltage of the threshold switching material, and the threshold switching device prepared from the threshold switching material has a higher on / off ratio, response speed, and thermal stability, which is beneficial to the preparation of the threshold switching device and the manufacturing and use processes of subsequent memory chips.

[0096] While elements As and Se can stabilize the network structure of the amorphous compound. Therefore, the larger the z value, that is, the higher the contents of elements As and Se, the smaller the threshold voltage drift coefficient of the threshold switching material, so that the threshold switching device prepared from the threshold switching material has higher stability.

[0097] In summary, by using the threshold switching material (In x Te 100-x ) 100-z (As 100-y Se y ) zControlling the ratio of InTe to AsSe within an appropriate range can reduce the threshold voltage drift and improve the working stability of the threshold switching device while ensuring its working performance.

[0098] In some embodiments, the mean coordination number (MCN) of the threshold switching material can be greater than or equal to 2.4 and less than or equal to 2.5. For example, the above-mentioned mean coordination number can be close to 2.45.

[0099] Optionally, MCN can satisfy the following formula:

[0100]

[0101] Wherein, MCN is the mean coordination number of the threshold switching material, x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, CN In is the coordination number of In atoms in the threshold switching material, CN Te is the coordination number of Te atoms in the threshold switching material, CN As is the coordination number of As atoms in the threshold switching material, CN Se is the coordination number of Se atoms in the threshold switching material.

[0102] Optionally, the coordination number of In atoms in the threshold switching material can be 5, the coordination number of Te atoms in the threshold switching material can be 2, the coordination number of As atoms in the threshold switching material can be 3, and the coordination number of Se atoms in the threshold switching material can be 2.

[0103] Taking (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 as an example for illustration, its MCN is:

[0104] MCN = 0.36 × 0.14 × 5 + 0.64 × 0.14 × 2 + 0.35 × 0.86 × 3 + 0.65 × 0.86 × 2 = 2.4522

[0105] When MCN is close to 2.45, it is the most stable state in the amorphous network structure of the threshold switching material, thereby being able to further improve the stability of the threshold switching device prepared from the threshold switching material.

[0106] It should also be noted that the above-mentioned threshold switching material (In xTe 100-x ) 100-z (As 100-y Se y ) z Can instantaneously transform from a high-resistance state to a low-resistance state under the operation of an electrical signal, and can instantaneously and spontaneously return to the high-resistance state when the electrical signal operation is removed.

[0107] An embodiment of the present application provides a threshold switch device based on the above-mentioned threshold switch material. Figure 3 It is a schematic structural diagram of a threshold switch device provided by an embodiment of the present application. Optionally, Figure 3 The shown threshold switch device can be applied to Figure 1 the shown memory 100, and can also be applied to Figure 2 the shown memory chip 121.

[0108] Such as Figure 3 shown, the selected threshold switch device may include a lower electrode layer 310, a threshold switch material layer 320 located above the lower electrode layer 310, and an upper electrode layer 330 located above the threshold switch material layer 320.

[0109] Among them, the chemical general formula of the threshold switch material in the threshold switch material layer 320 can be (In x Te 100-x ) 100-z (As 100-y Se y ) z , where x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switch material, and 30 ≤ x ≤ 50, 50 ≤ y ≤ 70, 50 ≤ z ≤ 90.

[0110] In some embodiments, the mean coordination number (MCN) of the threshold switch material can be greater than or equal to 2.4 and less than or equal to 2.5.

[0111] It should be understood that the above description is only an illustration of the relative positions between the lower electrode layer 310, the threshold switch material layer 320, and the upper electrode layer 330 in the threshold switch device, and does not limit the connection relationship between the layers. For example, the upper electrode layer 330 is located above the threshold switch material layer 320, which may be that the upper electrode layer 330 is directly disposed on the upper surface of the threshold switch material layer 320; it may also be that other layers, such as a buffer layer, a phase change material layer, etc., are disposed above the threshold switch material layer 320, and the upper electrode layer 330 is disposed above the above-mentioned other layers. The present application does not make specific limitations on this.

[0112] Optionally, the threshold switching material in the threshold switching material layer 320 may be the threshold switching material provided in the foregoing embodiments of the present application (In x Te 100-x ) 100-z (As 100-y Se y ) z . For specific descriptions of the composition and / or properties of the threshold switching material, reference may be made to the descriptions in the foregoing embodiments, which will not be elaborated herein.

[0113] In some embodiments, the thickness of the threshold switching material layer 320 is greater than or equal to 5 nm and less than or equal to 50 nm. As an example, the thickness of the threshold switching material layer 320 may be 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm, etc. By controlling the thickness of the threshold switching material layer, the threshold switching material layer can withstand the high-temperature process in the post-processing of the chip and maintain the threshold switching material in an amorphous phase.

[0114] Optionally, the thickness of the threshold switching material layer may be equal to 20 nm.

[0115] In some embodiments, the material of the lower electrode layer 310 may include, but is not limited to, at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0116] Optionally, the thickness of the lower electrode layer 310 may be 50 nm.

[0117] In some embodiments, the material of the upper electrode layer 330 may include, but is not limited to, at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0118] Optionally, the thickness of the upper electrode layer 310 may be 40 nm.

[0119] In some embodiments, the threshold switching device may further include an isolation material layer, which is coated on the side surfaces of the overall structure formed by the lower electrode layer, the threshold switching material layer, and the upper electrode layer. The isolation material layer can be used to prevent the threshold switching material from being oxidized.

[0120] It should be understood that the side surfaces of the overall structure may refer to all the surfaces of the overall structure except the lower surface of the lower electrode layer and the upper surface of the upper electrode layer. For example, the overall structure may be a cylindrical structure formed by stacking the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330. The lower surface of the cylinder is the lower surface of the lower electrode layer 310, and the upper surface of the cylinder is the upper surface of the upper electrode layer. Then, the isolation material layer can be coated on the side surfaces of the cylindrical structure.

[0121] Optionally, the threshold switch device may include a plurality of the above-described overall structures each composed of a lower electrode layer, a threshold switch material layer, and an upper electrode layer, and the isolation material layer may respectively cover the side surfaces of each overall structure. Each overall structure can serve as a select tube in a memory chip and is used to connect to a phase change memory cell in the memory chip. In this case, the isolation material layer can also be used to prevent interference between different select tubes.

[0122] In some embodiments, the isolation material of the isolation material layer may include, but is not limited to, Si 3 N 4 and / or SiO 2 .

[0123] The threshold switch device provided by the embodiments of the present application, by using the threshold switch material (In x Te 100-x ) 100-z (As 100-y Se y ) z , can reduce the threshold voltage drift on the basis of ensuring working performances such as the switching ratio and fatigue life, thereby improving the working stability.

[0124] For example, for the threshold switch device prepared from the above threshold switch material (In x Te 100-x ) 100-z (As 100-y Se y ) z , the threshold voltage offset coefficient within the relaxation time range of 10 -2 s to 10 2 s after the first turn-on can be less than or equal to 16.8 mV / dec, and the voltage drift range after 1 day of relaxation time can be 0.02 V to 0.22 V. In addition, the switching ratio of the threshold switch device prepared from the above threshold switch material (In x Te 100-x ) 100-z (As 100-y Se y ) z , that is, the logarithm of the ratio of the on-state current to the off-state current, can be greater than or equal to 4; the fatigue life, that is, the range of the number of cycles of effective switching, can be 2×10 8 to 3×10 9 .

[0125] Next, three specific embodiments will be used to introduce the threshold switch device provided by the embodiments of the present application.

[0126] Embodiment 1: The threshold switch material used is (In 36 Te 64) 14 (As 35 Se 65 ) 86 。

[0127] The lower electrode layer is formed on the silicon substrate, made of TiN with a thickness of 50 nm. The threshold switching material layer is formed on the upper surface of the lower electrode layer, and the threshold switching material is (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 , with a thickness of 20 nm. The upper electrode layer is formed on the upper surface of the threshold switching material layer, made of TiN with a thickness of 40 nm.

[0128] In addition, the overall structure composed of the lower electrode layer, the threshold switching material layer, and the upper electrode layer is a cylindrical structure with a diameter of 200 nm. That is, the projections of the lower electrode layer, the threshold switching material layer, and the upper electrode layer on the silicon substrate are all circles with a diameter of 200 nm. The spacing between multiple cylindrical structures is 200 nm.

[0129] Figure 4 It is the electrical performance test diagram of the threshold switching device in Example 1.

[0130] Figure 4 (a) in

[0130] is the voltage - current curve of the threshold switching device under the action of voltage excitation. The abscissa is the voltage applied to the threshold switching device, and the ordinate is the current corresponding to the threshold switching device. During the test, the voltage is cyclically applied to the threshold switching device. First, the applied voltage is gradually increased, and at this time, the current value continuously increases until the voltage reaches a certain critical value, and then the current jumps and increases rapidly; thereafter, the applied voltage is gradually decreased. The current first remains at the maximum value unchanged until the voltage reaches another critical value, and then the current jumps and decreases rapidly. The above complete process is called 1 cycle in the test.

[0131] Figure 4 In (a) of Figure 4 , the curves indicated by Roman numeral arrows Ⅰ to Ⅴ are the first cycle after the threshold switching device is fabricated. At this time, the threshold switching material needs to be activated, so the critical voltage required for the current to increase and jump is relatively large. Therefore, the first cycle can also be called the first fire of the threshold switching device. In the first fire, the critical voltage required for the current to increase and jump can be called the forming voltage, which is different from the threshold voltage in other cycle processes. For example, for the threshold switching material shown in the figure, the forming voltage is about 3 V. Until the externally applied voltage is less than about 1.4 V, the threshold switching device becomes in the off state, and the current passing through it is less than 10 -8 A, and the first fire is completed.

[0132] In other cycles except the first ignition, the critical voltage required for each current increase jump is the threshold voltage of the threshold switching device at this time. For example Figure 4 In (a) of Figure 4 , the curves indicated by the digital arrows 1 to 5 are the second cycle of the threshold switching device, that is, the first normal operation after being activated. When the applied voltage is less than about 1.4V, the threshold switching device is in the off state, and the current passing through is less than 10 -8 A; when the applied voltage increases to the threshold voltage (about 2V), the threshold switching device becomes on, the threshold switching material becomes in a low-resistance state, and the current passing through increases sharply to 10 -4 A; when the applied voltage decreases to about 1.4V again, the threshold switching unit becomes off again, the threshold switching material returns to the high-resistance state, and the current passing through decreases sharply. Figure 4 The test of (a) of Figure 4 shows that the initial threshold voltage of the threshold switching device in Example 1 is about 2V.

[0133] Figure 4 (b) in is a box plot of the statistical relationship between the relaxation time and the threshold voltage after the first ignition. The abscissa is the relaxation time after the first ignition of the threshold switching device, and the ordinate is the threshold voltage of the threshold switching device at different relaxation times. To improve the reliability of the statistical data, the number of threshold switching devices participating in the statistics is at least 40. Measure the threshold voltage of each threshold switching device at each test time point, and obtain the statistical data of the threshold voltages of multiple threshold switching devices. The statistical data may include but are not limited to the average value, median, quartiles, interquartile range (IQR), outliers, etc. According to Figure 4 The change of the median in (b) of Figure 4 shows that the threshold voltage changes little within the relaxation time of 100s after the start of the test and hardly drifts, indicating that the threshold switching device provided in Example 1 has good working stability.

[0134] It should be understood that Figure 4 (b) in Figure 4 taking the median of the threshold voltage as the reference standard is only an example for illustration, and other statistical data can also be used as the reference standard, which is not specifically limited in this application. For example, the average value of the threshold voltage does not show obvious fluctuations within the range of 10 -6 s to 10 2 s, which can also illustrate the working stability of the threshold switching device.

[0135] Figure 4In (c), the voltage-current curves after different relaxation times after the first ignition are shown. The abscissa is the voltage applied to the series structure composed of the threshold switching device and the fixed resistor, and the ordinate is the current corresponding to the threshold switching device. Among them, the rightmost curve is the cycling curve at the first ignition. Among the remaining curves, from left to right are the cycling curves with relaxation times of 10 -6 s, 1 day, and 1 month. The maximum voltage at the turning point of each curve is the threshold voltage. It can be seen that even when the relaxation time is extended to 1 day or even 1 month, the threshold voltage hardly drifts, showing good stability.

[0136] Figure 4 In (d), the curves of the on-state current and off-state current changing with the number of cycles are shown. The abscissa is the number of cycles of the cycling test, and the ordinate is the current corresponding to the threshold switching device. Among them, the solid dots represent the off-state current, that is, the current when the threshold switching device is in the off state; the hollow dots represent the on-state current, that is, the current when the threshold switching device is in the on state. Applying a high voltage for a certain period of time and a low voltage for a certain period of time can constitute one cycle. Among them, the duration of applying the high and low voltages respectively and the difference between the applied high voltage and low voltage can be set according to the required failure criteria, and this application does not make specific limitations. For example, it can be as Figure 4 shown in (d), applying a 30 ns high voltage and a 500 ns low voltage each time, and the difference between the high and low voltages is 2.8 V. When the threshold switching device cannot respond to the applied high voltage to generate a current jump, the threshold switching device fails. Therefore, it can be seen from the figure that the maximum number of cycles of the threshold switching device provided in Example 1 can exceed 2×10 8 times, and the current value is relatively stable during the cycling process.

[0137] In addition, according to the on-state current (also called the turn-on current) and off-state current (also called the leakage current) during the cycling process, the switching ratio of the threshold switching device at different relaxation times can also be calculated.

[0138] In summary, the turn-on current of the threshold switching device provided in Example 1 is greater than or equal to 10 -4 A, the leakage current is less than or equal to 10 -8 A, that is, the switching ratio is greater than or equal to 4, the threshold voltage is less than or equal to 2.4 V, the threshold voltage drift coefficient is almost 0, and the number of cycles is greater than or equal to 2×10 8 times.

[0139] Example 2: The threshold switching material used is (In 38 Te 62 ) 44 (As 41 Se 59 ) 56 .

[0140] The lower electrode layer is formed on a silicon substrate, made of TiN with a thickness of 50 nm. The threshold switching material layer is formed on the upper surface of the lower electrode layer, and the threshold switching material is (In 38 Te 62 ) 44 (As 41 Se 59 ) 56 , with a thickness of 20 nm. The upper electrode layer is formed on the upper surface of the threshold switching material layer, made of TiN with a thickness of 40 nm.

[0141] In addition, the overall structure composed of the lower electrode layer, the threshold switching material layer, and the upper electrode layer is a cylindrical structure with a diameter of 200 nm. That is, the projections of the lower electrode layer, the threshold switching material layer, and the upper electrode layer on the silicon substrate are all circles with a diameter of 200 nm. The spacing between multiple cylindrical structures is 200 nm.

[0142] Figure 5 It is the electrical performance test diagram of the threshold switching device in the second embodiment.

[0143] Figure 5 In (a), under the action of voltage excitation, it is the voltage-current curve of the threshold switching device. The curves indicated by the Roman numeral arrows i to v are the first ignition, with a formed voltage of about 2.8 V. Until the externally applied voltage is less than about 1.5 V, the threshold switching device becomes in the off state, and the current passing through is less than 10 -7 A, and the first ignition is completed. The curves indicated by the digital arrows 1' to 5' are the second cycle of the threshold switching device. When the applied voltage is less than about 1.5 V, the threshold switching device is in the off state, and the current passing through is less than 10 -7 A; when the applied voltage increases to the threshold voltage (about 1.5 V), the threshold switching device becomes on, the threshold switching material becomes in the low-resistance state, and the current passing through increases sharply to 10 -4 A; when the applied voltage is decreased to about 1.4 V again, the threshold switching unit becomes off again, the threshold switching material returns to the high-resistance state, and the current passing through decreases sharply. Therefore, the initial threshold voltage of the threshold switching device provided in the second embodiment is about 1.5 V.

[0144] Figure 5 In (b), it is the box plot of the statistical relationship between the relaxation time and the threshold voltage after the first ignition. Taking the median change as a reference, the threshold voltage drift coefficient corresponding to the drift of the threshold voltage within 100 s of relaxation time after the start of the test is about 16.8 mV / dec, indicating that the working stability of the threshold switching device provided in the second embodiment is also good.

[0145] Figure 5In (c), the voltage-current curves after different relaxation times after the first ignition are shown. Among them, the rightmost curve is the cyclic curve at the first ignition. Among the remaining curves, from left to right are the cyclic curves with relaxation times of 10 -6 s, 1 day of relaxation time, and 1 month of relaxation time. The maximum voltage at the turning point of each curve is the threshold voltage. It can be seen that after the relaxation time is extended to 1 day, the drift amount of the threshold voltage is about 0.22V, showing good stability.

[0146] Figure 5 In (d), the curves of the on-state current and off-state current changing with the number of cycles are shown. It can be seen that the maximum number of cycles of the threshold switching device provided in the second embodiment can exceed 3×10 9 times, indicating that the increase in the content of element In and element Te improves the fatigue performance of the threshold switching device.

[0147] In addition, the z value in the threshold switching material used in the threshold switching device can also be between that of the first embodiment and the second embodiment, such as the third embodiment described below.

[0148] Embodiment 3: The threshold switching material used is (In 35 Te 65 ) 24 (As 36 Se 64 ) 76 .

[0149] The lower electrode layer is formed on the silicon substrate, the material is TiN, and the thickness is 50nm. The threshold switching material layer is formed on the upper surface of the lower electrode layer, and the threshold switching material is (In 35 Te 65 ) 24 (As 36 Se 64 ) 76 , and the thickness is 20nm. The upper electrode layer is formed on the upper surface of the threshold switching material layer, the material is TiN, and the thickness is 40nm.

[0150] In addition, the overall structure composed of the lower electrode layer, the threshold switching material layer, and the upper electrode layer is a cylindrical structure with a diameter of 200nm. That is, the projections of the lower electrode layer, the threshold switching material layer, and the upper electrode layer on the silicon substrate are all circles with a diameter of 200nm. The distance between multiple cylindrical structures is 200nm.

[0151] Figure 6 is the electrical performance test diagram of the threshold switching device of Embodiment 3.

[0152] Figure 6Among them, (a) is a box plot of the statistical relationship between the relaxation time and the threshold voltage after the first ignition. Taking the median change as a reference, the threshold voltage drift coefficient corresponding to the threshold voltage drift within the relaxation time of 100 s after the start of the test is about 11.9 mV / dec.

[0153] Figure 6 Among them, (b) is the voltage-current curve after different relaxation times after the first ignition. Among them, the rightmost curve is the cyclic curve at the time of the first ignition. Among the remaining curves, from left to right are the cyclic curves with a relaxation time of 10 -6 s, a relaxation time of 1 day, and a relaxation time of 1 month. The maximum voltage at the turning point of each curve is the threshold voltage. It can be seen that after the relaxation time is extended to 1 day, the threshold voltage drift is about 0.18 V.

[0154] It should be understood that Example 3 is only an example. The z value of the threshold switching material can also be other values within the range of greater than or equal to 50 and less than or equal to 90, and the present application does not make specific limitations.

[0155] Table 1 shows the experimental results of each example and comparative example. The specific data can be seen in Table 1.

[0156] Table 1

[0157]

[0158] Combined with the above embodiments, the threshold switching device prepared from the threshold switching material provided by the present application can significantly reduce voltage drift compared with the currently commonly used threshold switching devices, thereby improving the working stability of the threshold switching device.

[0159] The embodiment of the present application provides a method for preparing the above-mentioned threshold switching device. Figure 7 It is a schematic flowchart of a method for preparing a threshold switching device provided by an embodiment of the present application. Optionally, Figure 7 The method shown can be used to prepare Figure 8 The threshold switching device shown.

[0160] As Figure 7 shown, the method includes the following steps.

[0161] Step S710: Form a lower electrode layer above the substrate.

[0162] For example, a lower electrode layer 310 can be deposited on the upper surface of the substrate material.

[0163] As an example, the silicon substrate 340 can be placed in acetone and ethanol solutions respectively, ultrasonically cleaned for 3 minutes in each solution, then dried at 120 °C for 20 minutes, and then the lower electrode layer 310 can be deposited on the cleaned and dried silicon substrate.

[0164] In some embodiments, the material of the lower electrode layer 310 may include, but is not limited to, at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0165] Optionally, the method for depositing the lower electrode layer 310 may include, but is not limited to, sputtering, chemical vapor deposition, atomic layer deposition, electron beam evaporation, etc.

[0166] As an example, the lower electrode layer 310 may be deposited on the silicon substrate 340 by magnetron sputtering. The material of the lower electrode layer 310 may be TiN, and the thickness may be 50 nm. Specifically, the base vacuum may be set to 4×10 -6 Torr, the vacuum during sputtering may be set to 0.18 Pa, and a TiN thin film with a thickness of 50 nm is deposited on the upper surface of the silicon substrate.

[0167] Step S720: Form a threshold switching material layer above the lower electrode layer.

[0168] For example, a threshold switching material layer may be deposited on the upper surface of the lower electrode layer. Among them, the chemical formula of the threshold switching material in the threshold switching material layer 320 may be (In x Te 100-x ) 100-z (As 100-y Se y ) z , where x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, and 30≤x≤50, 50≤y≤70, 50≤z≤90. For example, (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 , (In 35 Te 65 ) 24 (As 36 Se 64 ) 76 , (In 38 Te 62 ) 44 (As 41 Se 59 ) 56 etc.

[0169] Optionally, the threshold switching material in the threshold switching material layer 320 may be the threshold switching material provided in the foregoing embodiments of the present application (Inx Te 100-x ) 100-z (As 100-y Se y ) z , specific descriptions of the composition and / or properties of the threshold switching material can refer to the descriptions in the foregoing embodiments and will not be elaborated herein.

[0170] In some embodiments, the thickness of the threshold switching material layer 320 is greater than or equal to 5 nm and less than or equal to 50 nm. As an example, the thickness of the threshold switching material layer 320 can be 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm, etc.

[0171] Optionally, the thickness of the threshold switching material layer can be equal to 20 nm.

[0172] Optionally, the method of depositing the threshold switching material layer 320 can include, but is not limited to, sputtering, chemical vapor deposition, atomic layer deposition, electron beam evaporation, etc.

[0173] As an example, the threshold switching material layer 320 can be deposited on the lower electrode layer 310 by magnetron sputtering. The material of the threshold switching material layer 320 can be (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 , and the thickness can be 20 nm. Specifically, the background vacuum can be set to 4×10 -6 Torr, the vacuum during sputtering can be set to 0.2 Pa, and In 2 Te 3 and As 2 Se 3 are used as target materials for co-sputtering to deposit a 20-nm-thick (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 thin film on the upper surface of the lower electrode layer.

[0174] It should be understood that the above In 2 Te 3 and As 2 Se 3 are only one example of the sputtering target materials, and other compounds containing at least one of the elements In, Te, As, and Se can also be used as sputtering target materials. The present application does not make specific limitations thereon.

[0175] In some embodiments, the mean coordination number (MCN) of the threshold switching material can be greater than or equal to 2.4 and less than or equal to 2.5. As an example, the MCN of the threshold switching material can be close to 2.45, such as (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 。

[0176] Step S730: Form an upper electrode layer above the threshold switching material layer.

[0177] For example, the upper electrode layer 330 can be deposited on the upper surface of the threshold switching material layer 320.

[0178] In some embodiments, the material of the upper electrode layer 330 can include but is not limited to at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

[0179] Optionally, the method of depositing the upper electrode layer 330 can include but is not limited to sputtering, chemical vapor deposition, atomic layer deposition, electron beam evaporation, etc.

[0180] As an example, the upper electrode layer 330 can be deposited on the threshold switching material layer 320 by magnetron sputtering. The material of the upper electrode layer 330 can be TiN, and the thickness can be 40 nm. Specifically, the base vacuum can be set to 4×10 -6 Torr, the vacuum during sputtering can be set to 0.2 Pa, and a TiN thin film with a thickness of 40 nm is deposited on the upper surface of the threshold switching material layer.

[0181] By the above method, the prepared threshold switching device can reduce the threshold voltage drift on the basis of ensuring working performance such as the switching ratio and fatigue life, thereby improving the working stability.

[0182] In some embodiments, the above method further includes optional steps S740 and S750 for forming an isolation material layer, as follows.

[0183] S740: Etch partial positions of the lower electrode layer, the threshold switching material layer, and the upper electrode layer.

[0184] For example, as Figure 9As shown, the overlapping portions of the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330 in the horizontal direction can be etched away, thereby forming one or more integral structures stacked by the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330 in the horizontal direction.

[0185] It should be understood that as Figure 9 shown, the etched portion penetrates through the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330 in the horizontal direction and contacts the silicon substrate 340. Therefore, in the case where a plurality of the above-mentioned integral structures are formed, the plurality of integral structures do not contact each other, so that each integral structure can be used as a select tube in a memory chip for connecting to a phase change memory cell in the memory chip.

[0186] In some embodiments, the above-mentioned integral structure may be a columnar structure. As an example, the projections of the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330 in each integral structure on the silicon substrate 340 are circles of the same size, and the projections of the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330 on the silicon substrate 340 overlap, so that the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330 are stacked to form a cylindrical structure.

[0187] It should be understood that the above-mentioned cylindrical structure is only an example of the foregoing integral structure, and the integral structure may also be other shapes, such as a frustum structure, or a cuboid structure with a rectangular projection, etc. The present application does not make specific limitations thereon.

[0188] Optionally, the diameter of the cylindrical structure is 200 nm.

[0189] Optionally, the spacing between each columnar structure may be 200 nm. It should be understood that in the case where the columnar structure is a cylindrical structure, the spacing refers to the shortest distance between points on the side surfaces of two cylinders. As an example, as Figure 9 described, in the case where the cylinder diameter is 200 nm and the spacing is 200 nm, the distance between the centers of the circular projections of the two cylinders is 400 nm.

[0190] As an example, after step S730, one or more circles with a diameter of 100 and a spacing of 100 nm can be lithographed on the upper surface of the upper electrode layer 330 using extreme ultraviolet lithography technology. Then, the portions outside the circles can be etched away using reactive ion etching, and the etching depth reaches at least the upper surface of the silicon substrate, thereby forming a columnar structure stacked by the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330.

[0191] S750: Deposit an isolation material at the etched portion.

[0192] For example, as Figure 10 shown, an isolation material may be deposited on the portion that can be etched away in S740 to form an isolation material layer 350.

[0193] It should be understood that in the above manner, the isolation material layer 350 can cover the side surfaces of the columnar structure formed by superimposing the lower electrode layer 310, the threshold switching material layer 320, and the upper electrode layer 330. Among them, the side surfaces of the columnar structure may refer to all surfaces of the columnar structure except the lower surface of the lower electrode layer and the upper surface of the upper electrode layer.

[0194] In some embodiments, the isolation material of the isolation material layer may include, but is not limited to, Si 3 N 4 and / or SiO 2 .

[0195] As an example, on the upper surface of the silicon substrate 340 exposed after etching in S640, Si 3 N 4 thin film may be deposited by chemical vapor deposition (CVD), and the Si 3 N 4 with a height exceeding the upper surface of the upper electrode layer 330 may be removed by chemical mechanical polishing, so as to form an isolation material layer 350 as Figure 10 shown.

[0196] It should be understood that the above manner is only an example of depositing the isolation material layer 350, and the isolation material layer 350 may also be deposited by other methods, which are not specifically limited in this application.

[0197] By the above method, the threshold switching material can be prevented from being oxidized, and interference between different select tubes can be avoided.

[0198] An embodiment of this application further provides a storage chip, which may include the threshold switching device provided in the embodiment of this application.

[0199] Optionally, the above storage chip may further include at least one storage unit, and each storage unit may be connected to the threshold switching device or an overall structure in the threshold switching device.

[0200] An embodiment of this application further provides a memory, which may include the storage chip provided in the embodiment of this application.

[0201] Optionally, the above memory may further include a controller for performing read and write operations on the data in the storage chip.

[0202] The embodiments of the present application further provide a computing device, which may include the storage chip provided in the embodiments of the present application above, or may include the memory provided in the embodiments of the present application above.

[0203] Optionally, the above computing device may be, including but not limited to, a desktop computer, a laptop computer, a smart phone, a tablet computer, a personal digital assistant (PDA), a wearable device, a smart speaker, a television, a drone, a vehicle, an in-vehicle device (such as a car stereo, an in-vehicle computer, an in-vehicle chip, etc.), or a robot, etc.

[0204] As mentioned above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A threshold switching material, characterized in that, The chemical general formula of the threshold switching material is (In x Te 100-x ) 100-z (As 100-y Se y ) z , where x is the atomic percentage of element In in elements In and Te, y is the atomic percentage of element Se in elements As and Se, z is the atomic percentage of elements As and Se in the threshold switching material, and 30 ≤ x ≤ 50, 50 ≤ y ≤ 70, 50 ≤ z ≤ 90.

2. The threshold switching material according to claim 1, characterized in that, the average coordination number of the threshold switching material is greater than or equal to 2.4 and less than or equal to 2.

5.

3. The threshold switching material according to claim 1 or 2, characterized in that, The chemical general formula of the threshold switching material is (In 36 Te 64 ) 14 (As 35 Se 65 ) 86 .

4. The threshold switching material according to claim 1, characterized in that, The chemical general formula of the threshold switching material is (In 38 Te 62 ) 44 (As 41 Se 59 ) 56 .

5. A threshold switching device, characterized in that, comprising: a lower electrode layer; a threshold switching material layer located above the lower electrode layer; an upper electrode layer located above the threshold switching material layer; wherein, the threshold switching material layer comprises the threshold switching material according to any one of claims 1 to 4.

6. The threshold switching device according to claim 5, characterized in that, the threshold switching device further comprises: an isolation material layer, and the isolation material layer coats the side surfaces of the overall structure composed of the lower electrode layer, the threshold switching material layer, and the upper electrode layer.

7. The threshold switching device according to claim 6, characterized in that, The isolation material of the isolation material layer includes Si 3 N 4 and / or SiO 2 .

8. The threshold switching device according to any one of claims 5 to 7, characterized in that, the thickness of the threshold switching material layer is greater than or equal to 5 nm and less than or equal to 50 nm.

9. The threshold switching device according to any one of claims 5 to 8, characterized in that, the material of the lower electrode layer comprises at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

10. The threshold switching device according to any one of claims 5 to 9, characterized in that, the material of the upper electrode layer comprises at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

11. A method for manufacturing a threshold switching device, characterized in that, comprising: forming a lower electrode layer above a substrate; forming a threshold switching material layer above the lower electrode layer; forming an upper electrode layer above the threshold switching material layer; wherein, the threshold switching material layer comprises the threshold switching material according to any one of claims 1 to 4.

12. The method according to claim 11, characterized in that, the method further comprises: etching partial positions of the lower electrode layer, the threshold switching material layer, and the upper electrode layer to form a columnar structure composed of the lower electrode layer, the threshold switching material layer, and the upper electrode layer; depositing an isolation material at the etched partial positions to form an isolation material layer.

13. The method according to claim 12, characterized in that, The isolation material includes Si 3 N 4 and / or SiO 2 .

14. The method according to any one of claims 11 to 13, characterized in that, the thickness of the threshold switching material layer is greater than or equal to 5 nm and less than or equal to 50 nm.

15. The method according to any one of claims 11 to 14, characterized in that, The material of the lower electrode layer includes at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

16. The method according to any one of claims 11 to 15, wherein, the material of the upper electrode layer includes at least one of C, Ta, TiN, TaC, TaN, Co, W, Pt, Au, Ti, Al, Ag, Cu, Ni.

17. A storage chip, wherein, it includes a storage unit and a threshold switching device according to any one of claims 5 to 10.

18. A memory, wherein, it includes the storage chip according to claim 17.

19. A computing device, wherein, it includes the storage chip according to claim 17.

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