A threshold switching material, a threshold switching device and a method for manufacturing the same

Abstract

This invention discloses a threshold switching material, a threshold switching device, and a method for preparing the same. The chemical formula of the threshold switching material is M. x D 1‑x Wherein, M is one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta, and D is one of S, Se, and Te, with 0.1 ≤ x ≤ 0.8. In this invention, M is selected from metallic elements, which have good conductivity. This is beneficial for increasing the driving current and reducing the randomness of conductive path formation, thereby improving the switching speed of threshold switching devices based on this threshold switching material. The unique d-orbital electronic structure of the selected M elements makes M... x D 1‑x The high crystallization activation energy results in a lower leakage current. The selected element M has an atomic number greater than 20, a small atomic diffusion coefficient, and is less prone to component segregation, resulting in high stability and thus contributing to a longer fatigue life and higher device reliability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor microelectronics technology, and in particular to a threshold switching material, a threshold switching device, and a method for preparing the same. Background Technology

[0002] Memory is a crucial component of the current semiconductor market and a cornerstone of information technology, playing a vital role in daily life and the national economy. With the rapid development of the semiconductor industry, semiconductor process technology has also significantly improved, prompting the development of device structures towards three dimensions, leading to advanced 3D storage technologies such as 3D Xpoint. Compared to traditional 2D storage technologies, 3D storage technologies offer higher storage density, lower power consumption, longer lifespan, faster read / write speeds, and lower costs. As one of the most promising next-generation non-volatile memories, phase-change memories (PCMs) offer advantages such as fast read / write speeds, low operating power consumption, good cycle life, and good resistance to vibration and radiation. In high-density integrated 3D cross-connect arrays, to achieve good overall performance, not only are high-performance memory cells required, but also switching cells with performance matching the memory cells are needed to eliminate the impact of leakage current from selected cells on unselected cells. Among the many switching cell devices that can serve as PCM cells, ovonic threshold switches, which also utilize chalcogenide thin films as the dielectric, are considered the most valuable switching devices for application. Threshold switching devices mainly consist of upper and lower electrode materials, a chalcogenide compound thin film material with volatile threshold transition characteristics, and an insulating dielectric material protecting the chalcogenide compound thin film material from oxidation. The working principle of a threshold switching device is to use electrical signals to control the switching of the device. When an electrical signal is applied and certain conditions are met, the threshold switching material changes from a high-resistance state to a low-resistance state, and the threshold switching device is in the on state. Different types of pulse signals can be applied to the phase-change memory cell to cause the phase-change memory material to undergo a reversible transition between high and low resistance, thereby storing logic "0" and "1". When the electrical signal applied to the threshold switching device is lower than a certain value, the threshold switching material changes from a low-resistance state to a high-resistance state, and the threshold switching device is in the off state. At this time, leakage current from other cells will not affect the resistance state of this memory cell, ensuring the reliability of information storage.

[0003] Traditional threshold switch materials are mostly multi-component systems containing As, Se, etc., which have advantages such as good thermal stability, low leakage current, and long cycle life, but their performance is unsatisfactory in terms of switching speed and drive current. Furthermore, multi-component materials are prone to component segregation during repeated device operation, affecting device performance stability. Additionally, As is toxic. Therefore, there is an urgent need to develop environmentally friendly and compositionally simplified binary threshold switch material systems. Currently reported threshold switch devices based on binary systems such as B-Te, C-Te, and Si-Te exhibit relatively fast switching speeds, but suffer from problems such as low drive current, high leakage current, short cycle life, and poor stability.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a threshold switching material, a threshold switching device and a method for preparing the same, in order to solve the problems of low driving current, high leakage current, short cycle life and poor stability of existing threshold switching devices based on binary threshold switching materials.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a threshold switching material, wherein the chemical formula of the threshold switching material is M x D 1-x Where M is one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta, and D is one of S, Se, and Te, and 0.1 ≤ x ≤ 0.8.

[0008] A second aspect of the present invention provides a threshold switching device, comprising a first electrode, a threshold switching material layer, and a second electrode stacked sequentially from bottom to top, wherein the threshold switching material layer comprises the threshold switching material of the present invention as described above.

[0009] Optionally, the threshold switching device further includes:

[0010] A dielectric coating layer covers the side surface of the integral structure consisting of the first electrode, the threshold switch material layer, and the second electrode, which are stacked sequentially.

[0011] Optionally, the threshold switching device further includes:

[0012] A substrate having a through-hole, wherein the first electrode is disposed in the through-hole, and the threshold switch material layer is disposed on the substrate and the first electrode;

[0013] A dielectric coating layer covers the side surface of the entire assembly consisting of the stacked threshold switch material layer and the second electrode.

[0014] Optionally, the material of the first electrode is selected from at least one of W, TiW, TiN, and TiSiN.

[0015] Optionally, the material of the second electrode is selected from at least one of W, TiW, and TiN.

[0016] Optionally, the material of the dielectric coating layer is selected from at least one of SiO2 and Si3N4.

[0017] Optionally, the thickness of the threshold switching material layer is 2–40 nm.

[0018] Optionally, the substrate material is selected from at least one of SiO2 and Si3N4.

[0019] A third aspect of the present invention provides a method for fabricating a threshold switching device, comprising the steps of:

[0020] Provide the first electrode;

[0021] A threshold switching material layer is formed on the first electrode, wherein the material of the threshold switching material layer includes the threshold switching material of the present invention as described above;

[0022] A second electrode is formed on the threshold switching material layer.

[0023] Beneficial effects: The threshold switching material M provided by this invention x D 1-x This invention features volatile threshold switching capabilities, where M is selected from one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta. Compared to existing binary threshold switching materials, the M elements selected in this invention are all metallic elements with good conductivity. This facilitates increased driving current and the formation of nodes for specific conductive paths, reducing the randomness of conductive path formation and improving the switching speed of threshold switching devices based on this material. The unique d-orbital electronic structure of the selected M elements results in a higher crystallization activation energy when combined with one of S, Se, or Te, leading to lower leakage current. The selected M elements have atomic numbers greater than 20, large atomic radii, and low atomic diffusion coefficients, making the material less prone to component segregation and highly stable, thus contributing to longer fatigue life and higher device reliability. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the restricted structure threshold switch device in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the T-shaped threshold switch device in an embodiment of the present invention.

[0026] Figure 3 The image shows the current-voltage performance curve of the T-type threshold switching device in Embodiment 1 of the present invention.

[0027] Figure 4 The fatigue cycle performance curve of the T-type threshold switch device in Embodiment 1 of the present invention is shown. Detailed Implementation

[0028] This invention provides a threshold switching material, a threshold switching device, and a method for preparing the same. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0030] This invention provides a threshold switching material, wherein the chemical formula of the threshold switching material is M. x D 1-x Where M is one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta, and D is one of S, Se, and Te, and 0.1 ≤ x ≤ 0.8 (x represents the percentage of M atoms in M). x D 1-x The ratio of the total number of atoms, x to 1-x, is the ratio of the number of atoms of element M to the number of atoms of element D.

[0031] The threshold switching material M provided in this embodiment of the invention x D 1-xThis invention is an alloy material composed of M and D, possessing volatile threshold switching capabilities. M is selected from one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta. Compared to existing binary threshold switching materials, the M elements selected in this invention are all metallic elements, exhibiting good conductivity. This facilitates increased drive current and the formation of nodes for specific conductive paths, reducing the randomness of path formation and improving the switching speed of threshold switching devices based on this material. The unique d-orbital electronic structure of the selected M elements results in a higher crystallization activation energy when combined with one of S, Se, or Te, leading to lower leakage current. Furthermore, the selected M elements have atomic numbers greater than 20, large atomic radii, and low atomic diffusion coefficients, making the material less prone to compositional segregation during repeated device operation, resulting in high stability and thus longer fatigue life and higher device reliability.

[0032] This invention provides a threshold switching device, wherein, as shown in the embodiments of the present invention, a threshold switching device is provided. Figure 1-2 As shown, it includes a first electrode 1, a threshold switching material layer 2, and a second electrode 3 stacked sequentially from bottom to top. The threshold switching material layer 2 includes the threshold switching material described above in the embodiments of the present invention.

[0033] In this embodiment of the invention, the threshold switching material layer of the threshold switching device adopts M with volatile threshold switching function. x D 1-x Compared to existing binary threshold switch materials, the elements selected for M are all metallic elements (M is one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta). These elements have good conductivity, which on the one hand helps to increase the driving current of the device, and on the other hand, facilitates the formation of nodes for specific conductive paths, reducing the randomness of conductive path formation and improving the switching speed of the threshold switch device. The elements selected for M have atomic numbers greater than 20, large atomic radii, and small atomic diffusion coefficients, making the material less prone to compositional segregation and highly stable, resulting in a longer fatigue life and higher reliability for the threshold switch device. The unique d-orbital electronic structure of the elements selected for M allows for a higher crystallization activation energy when combined with one of S, Se, or Te, resulting in a lower leakage current for the threshold switch device. Therefore, the threshold switch device provided in this invention can achieve nonlinear switching characteristics, with advantages such as high driving current, low leakage current, large on / off ratio, fast switching speed (below 10 ns), long cycle life, and high reliability. It can be combined with resistive switching and phase-change memory units to realize high-density, high-performance information storage chips.

[0034] In this embodiment, the threshold switching material layer in the threshold switching device has a high resistance in the off-state and a low resistance in the on-state when it is conducting, wherein the high resistance RH The value is: 40Ω·cm≤R H ≤2×10 5 Ω·cm; Low-resistivity R L The size is: 4×10 -5 Ω·cm≤R L ≤2×10 -3 Ω·cm; Volatile threshold transition voltage V th The value is: 0.5V ≤ V th ≤5V. The threshold switching material in the threshold switching device is initially amorphous and remains amorphous during the volatile electrical threshold transition operation.

[0035] In this embodiment of the invention, the threshold switching device includes two structures, one of which is a confinement structure, such as... Figure 1 As shown, the restricted-structure threshold switching device includes:

[0036] First electrode 1;

[0037] A threshold switching material layer 2 is disposed on the first electrode 1, and the threshold switching material layer 2 includes the threshold switching material described above in the embodiments of the present invention;

[0038] The second electrode 3 is disposed on the threshold switch material layer 2;

[0039] A dielectric coating layer 4 is applied to the side surface of the entire assembly consisting of the first electrode 1, the threshold switch material layer 2, and the second electrode 3. The function of the dielectric coating layer is to prevent oxidation of the threshold switch material.

[0040] In one embodiment, the first electrode is cylindrical, and its diameter is 50–150 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm. The diameter of the first electrode affects the drive current, cycle life, and storage density of the threshold switching device, and the larger the diameter of the first electrode, the worse the overall performance of the threshold switching device. Therefore, when the diameter of the first electrode is 50–150 nm, the overall performance of the threshold switching device is better.

[0041] In the restricted structure, the shape and diameter of the second electrode are the same as those of the first electrode, and there are no specific requirements for the thickness of the first and second electrodes. They can be set according to actual needs. For example, the thickness of the first electrode and the thickness of the second electrode can be 20 to 500 nm, such as 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm or 500 nm.

[0042] In one embodiment, the thickness of the threshold switch material layer is 2–40 nm, for example, it can be 2 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, or 40 nm. By controlling the composition of the threshold switch material layer and optimizing its thickness, the threshold switch material layer can withstand the high-temperature back-end processes of CMOS and maintain the threshold switch material as an amorphous phase.

[0043] In one embodiment, the material of the first electrode is selected from at least one of W, TiW, TiN, and TiSiN, but is not limited thereto.

[0044] In one embodiment, the material of the second electrode is selected from at least one of W, TiW, and TiN, but is not limited thereto.

[0045] In one embodiment, the dielectric coating layer is selected from at least one of SiO2 and Si3N4, but is not limited thereto.

[0046] Another structure is the T-shaped structure, such as Figure 2 As shown, the T-type threshold switch device includes:

[0047] Substrate 5 with through holes;

[0048] The first electrode 1 is disposed in the through hole;

[0049] A threshold switching material layer 2 is disposed on the substrate 5 and the first electrode 1, and the threshold switching material layer 2 includes the threshold switching material of the present invention as described above;

[0050] The second electrode 3 is disposed on the threshold switch material layer 2;

[0051] The dielectric coating layer 4 covers the side surface of the entire structure consisting of the threshold switch material layer 2 and the second electrode 3. The function of the dielectric coating layer is to prevent oxidation of the threshold switch material.

[0052] In one embodiment, the first electrode is cylindrical, and its diameter is 50–150 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm. The size of the first electrode diameter affects the drive current, cycle life, and storage density of the threshold switching device, and the larger the first electrode diameter, the worse the overall performance of the threshold switching device. Therefore, when the diameter of the first electrode is 50–150 nm, the overall performance of the threshold switching device is better.

[0053] In one embodiment, the thickness of the first electrode is 100–500 nm, meaning the thickness of the substrate with the through-hole is 100–500 nm, for example, it can be 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, or 500 nm. The selection of the first electrode thickness mainly considers the substrate covering the first electrode (this substrate is an insulating material and can prevent the first electrode from oxidizing). If the substrate thickness is too thin, leakage current will occur, affecting the actual effective utilization efficiency of the device's electrical energy. Therefore, setting the thickness of the first electrode to 100–500 nm (the substrate thickness is also 100–500 nm) ensures that the substrate thickness is not too thin, thus avoiding leakage current.

[0054] In the T-structure, a threshold switching material layer is disposed on the substrate and the first electrode, meaning the area of ​​the threshold switching material layer is larger than that of the first electrode, and the projection of the threshold switching material layer onto the substrate completely covers the first electrode. Furthermore, the projection of the first electrode onto the threshold switching material layer is located at the center of the threshold switching material layer.

[0055] Furthermore, the shape of the horizontal cross-section of the threshold switching material layer can be either square or rectangular; in the horizontal direction, the side length of the threshold switching material layer is at least twice the diameter of the first electrode. The active region of the threshold switching material layer above the first electrode is generally a hemisphere, and this multiple ensures that the active region of the threshold switching material layer completely covers the first electrode.

[0056] In one embodiment, the thickness of the threshold switch material layer is 2–40 nm. By controlling the composition and optimizing the thickness of the threshold switch material layer, the threshold switch material layer can withstand the high-temperature back-end processes of CMOS and remain an amorphous phase of the threshold switch material.

[0057] In the T-structure, the shape and size of the second electrode are the same as those of the threshold switch material layer, and the thicknesses of both are equal.

[0058] In one embodiment, the substrate material is selected from at least one of SiO2 and Si3N4, but is not limited thereto.

[0059] In one embodiment, the material of the first electrode is selected from at least one of W, TiW, TiN, and TiSiN.

[0060] In one embodiment, the material of the second electrode is selected from at least one of W, TiW, and TiN.

[0061] In one embodiment, the material of the dielectric coating layer is selected from at least one of SiO2 and Si3N4, but is not limited thereto.

[0062] This invention also provides a method for fabricating a threshold switching device, comprising the following steps:

[0063] S1, Provide the first electrode;

[0064] S2. A threshold switching material layer is formed on the first electrode, wherein the material of the threshold switching material layer includes the threshold switching material described above in the embodiments of the present invention;

[0065] S3. A second electrode is formed on the threshold switching material layer.

[0066] In this embodiment, the specific composition, shape, thickness, etc. of the first electrode, the second electrode, and the threshold switch material are as described above and will not be repeated here.

[0067] In step S1, the preparation method of the first electrode includes, but is not limited to, one of sputtering, evaporation, physical vapor deposition, chemical vapor deposition, plasma-enhanced chemical vapor deposition, molecular beam epitaxy, atomic layer deposition, atomic vapor deposition, and metal compound vapor deposition.

[0068] In step S2, a threshold switching material can be formed on the first electrode by means of one of the following methods, including but not limited to sputtering, evaporation, physical vapor deposition, chemical vapor deposition, plasma-enhanced chemical vapor deposition, molecular beam epitaxy, atomic layer deposition, atomic vapor deposition, and metal compound vapor deposition.

[0069] In step S3, a second electrode may be formed on the threshold switch material layer by means of, but not limited to, sputtering, evaporation, physical vapor deposition, chemical vapor deposition, plasma-enhanced chemical vapor deposition, molecular beam epitaxy, atomic layer deposition, atomic vapor deposition, and metal compound vapor deposition.

[0070] Following step S3, the method for fabricating the threshold switching device further includes the following steps:

[0071] The first electrode, threshold switch material layer, and second electrode, which are stacked sequentially, are treated as a whole and photolithographically etched to form a preset shape, ensuring that the projection of the first electrode onto the threshold switch material layer is located at the center of the threshold switch material layer. Alternatively, the shapes of the first electrode, threshold switch material layer, and second electrode can be preset in the above steps, and the preset shape can be obtained after stacking, eliminating the need for final etching.

[0072] The following detailed description uses specific examples.

[0073] Example 1

[0074] like Figure 2As shown, this embodiment provides a T-shaped threshold switch device, including a substrate 5 with a through hole, wherein the through hole is formed in the substrate 5; a first electrode 1 disposed in the through hole; a threshold switch material layer 2 disposed on the substrate 5 and the first electrode 1; and a second electrode 3 disposed on the threshold switch layer 2; and further including a dielectric coating layer 4, which covers the side of the whole formed by the threshold switch material layer 2 and the second electrode 3, wherein the projection of the first electrode on the threshold switch material layer is located at the center of the threshold switch material layer.

[0075] The first electrode is made of TiN, is cylindrical, has a diameter of 100 nm, and a thickness of 200 nm; the second electrode is made of W, is cuboid (i.e., a cuboid with a square base), has a horizontal cross-section of a square with a side length of 10 μm, and a vertical thickness of 8 nm.

[0076] The threshold switch material is Sc 0.4 Te 0.6 The shape and size of the threshold switch material layer are the same as those of the second electrode (it is a square with a bottom side length of 10μm and a cuboid with a thickness of 8nm);

[0077] The dielectric coating layer is made of SiO2 and has a vertical height of 16 nm.

[0078] The fabrication method of the T-type threshold switch device includes the following steps:

[0079] A SiO2 substrate with through holes is provided with a thickness of 200 nm, and the diameter of the through holes is 100 nm and the height is 200 nm.

[0080] A cylindrical TiN layer with a diameter of 100 nm and a thickness of 200 nm was prepared in a through-hole by chemical vapor deposition to form the first electrode;

[0081] The base vacuum of magnetron sputtering is 1×10⁻⁶. -5 During sputtering, the Ar gas pressure inside the cavity was 0.2 Pa. A Sc single-element target (sputtering power of 50 W) and a Te single-element target (sputtering power of 15 W) were used to co-sputter on the first electrode for 3 minutes, resulting in a Sc layer with a thickness of 8 nm and a bottom edge length of 10 μm. 0.4 Te 0.6 A layer (with a square cross-section in the horizontal direction) is formed to create a threshold switch material layer;

[0082] A TiN layer with a thickness of 8 nm was deposited on the threshold switch material layer using chemical vapor deposition. A pattern with a bottom side length of 10 μm (a square cross-section in the horizontal direction) was obtained by photolithography etching to form the second electrode.

[0083] Next, 30 nm of SiO2 is deposited using chemical vapor deposition, and then the SiO2 on the second electrode is removed by chemical mechanical polishing. The SiO2 remaining around the second electrode and the threshold switch material layer forms a dielectric coating layer.

[0084] Testing revealed that the high-resistivity R state of the threshold switching material layer in the T-structure threshold switch device of Example 1... H 1.6×10 3 Ω·cm, low resistance state R L 1.2×10 -3 Ω·cm, volatile threshold transition voltage V th It is 1.1V.

[0085] The current-voltage operating performance curve of the T-structure threshold switch device in Example 1 is as follows: Figure 3 As shown, the threshold switching device can achieve a high-resistance to low-resistance transition to turn-on operation at a threshold voltage of 1.1V, and a high-resistance to low-resistance turn-off operation when the voltage drops to 0.2V. Unlike metal tellurides such as TiTe2, which always remain in a low-resistance state and cannot achieve switching operation, this embodiment is based on an 8nm thick Sc 0.4 Te 0.6 The threshold switching device in the layer can realize threshold switching operation. Furthermore, by... Figure 3 It can be seen that the drive current of the T-structure threshold switch device in Example 1 is 1×10⁻⁶. -3 A, leakage current is 1×10 -10 A.

[0086] The fatigue cycle performance curve of the T-structure threshold switch device in Example 1 is as follows: Figure 4 As shown, during repeated switching operations 1×10 9 After this, the threshold switching device still did not fail, and the switching ratio was at least 7 orders of magnitude.

[0087] Based on testing, according to existing B 0.3 Te 0.7 The T-structure threshold switch device (the only difference from Example 1 is that the threshold switch material is B) 0.3 Te 0.7 The drive current is 1×10 -4 A, leakage current is 1×10 -9 A, cycle life is 1×10 8 Next. Based on existing C 0.35 Te 0.65 The T-structure threshold switch device (the only difference from Example 1 is that the threshold switch material is C) 0.35 Te 0.65 The drive current is 5 × 10 -4A, leakage current is 5×10 -9 A, cycle life is 1×10 8 Based on existing Si 0.24 Te 0.76 The T-structure threshold switch device (the only difference from Example 1 is that the threshold switch material is Si) 0.24 Te 0.76 The drive current is 8 × 10 -4 A, leakage current is 8×10 -10 A, cycle life is 1×10 5 The above data is summarized in Table 1 below.

[0088] Table 1 Test data for different threshold switching devices

[0089]

[0090] As can be seen, the T-type threshold switching device provided by the present invention has higher drive current, lower leakage current, longer cycle life and better stability compared with existing threshold switching devices based on binary systems such as B-Te, C-Te and Si-Te.

[0091] Example 2

[0092] This embodiment provides a T-shaped threshold switch device, which differs from Embodiment 1 only in that the threshold switch material is Gd. 0.5 Se 0.5 .

[0093] The fabrication method of the T-structure threshold switch device differs from that in Example 1 only in that:

[0094] The base vacuum of magnetron sputtering is 1×10⁻⁶. -5 During sputtering, the Ar gas pressure inside the cavity was 0.2 Pa. A Gd single-element target (sputtering power of 40 W) and a Se single-element target (sputtering power of 15 W) were co-sputtered on the first electrode for 3 minutes to obtain a Gd layer with a thickness of 8 nm and a bottom edge length of 10 μm. 0.5 Se 0.5 A layer (with a square cross-section in the horizontal direction) is formed to create a threshold switch material layer.

[0095] Testing revealed that the T-shaped threshold switch device provided in this embodiment has similar threshold transition characteristics to that of Embodiment 1.

[0096] Example 3

[0097] like Figure 1As shown, this embodiment provides a restricted structure threshold switch device, including a first electrode 1, a threshold switch material layer 2 and a second electrode 3 stacked sequentially from bottom to top, and also includes a dielectric coating layer 4 covering the side of the whole formed by the sequentially stacked first electrode 1, threshold switch material layer 2 and second electrode 3.

[0098] The first electrode is made of TiN, is cylindrical, has a diameter of 100 nm, and a thickness of 20 nm; the second electrode is also made of TiN, is cylindrical, has a diameter of 100 nm, and a thickness of 20 nm.

[0099] The threshold switch material is Lu 0.4 Te 0.6 The threshold switch material layer has a thickness of 10 nm and the same shape and diameter as the first electrode; the dielectric coating layer is made of SiO2 and has a vertical height of 50 nm.

[0100] The method for fabricating the restricted-structure threshold switch device includes the following steps:

[0101] A 20 nm thick TiN layer was prepared using magnetron sputtering.

[0102] The base vacuum of magnetron sputtering is 1×10⁻⁶. -5 During sputtering, the Ar gas pressure inside the cavity was 0.2 Pa. A Lu single-element target (sputtering power 60 W) and a Te single-element target (sputtering power 15 W) were used to co-sputter the TiN layer for 4 minutes, resulting in a Lu layer with a thickness of 10 nm. 0.4 Te 0.6 layer;

[0103] Magnetron sputtering in Lu 0.4 Te 0.6 A 20 nm thick TiN layer was fabricated on the substrate.

[0104] The device obtained above was subjected to photolithography etching to obtain a cylindrical pattern with a diameter of 100nm, which consists of a first electrode, a threshold switch material layer, and a second electrode from bottom to top.

[0105] Next, 80nm SiO2 was prepared by magnetron sputtering, and then the SiO2 on the second electrode was removed by chemical mechanical polishing. The SiO2 remaining around the first electrode, the second electrode and the threshold switch material layer formed a dielectric coating layer.

[0106] Tests showed that it has similar threshold transition characteristics to Example 1.

[0107] In summary, this invention provides a threshold switching material, a threshold switching device, and a method for fabricating the same. The threshold switching material M provided by this invention...x D 1-x This invention features volatile threshold switching capabilities. The element M is selected from one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta. Compared to existing binary threshold switching materials, the elements selected for M in this invention are all metallic elements with good conductivity. This facilitates increased driving current and the formation of nodes for specific conductive paths, reducing the randomness of path formation and improving the switching speed of threshold switching devices based on this material. The unique d-orbital electronic structure of the selected elements allows for higher crystallization activation energy when combined with one of S, Se, or Te, resulting in lower leakage current. The selected elements have atomic numbers greater than 20, large atomic radii, and low atomic diffusion coefficients, making the material less prone to component segregation and highly stable, thus contributing to longer fatigue life and higher device reliability.

[0108] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A threshold switching material, characterized in that, The chemical formula of the threshold switch material is M x D 1-x Where M is one of La, Ce, Gd, Lu, Sc, Y, Zr, Mo, Hf, W, and Ta, and D is one of S, Se, and Te, and 0.1 ≤ x ≤ 0.8; The threshold switch material is amorphous.

2. A threshold switching device, characterized in that, It includes a first electrode, a threshold switching material layer, and a second electrode stacked sequentially from bottom to top, wherein the threshold switching material layer includes the threshold switching material as described in claim 1.

3. The threshold switching device according to claim 2, characterized in that, The threshold switching device further includes: A dielectric coating layer covers the side surface of the integral structure consisting of the first electrode, the threshold switch material layer, and the second electrode, which are stacked sequentially.

4. The threshold switching device according to claim 2, characterized in that, The threshold switching device further includes: A substrate having a through-hole, wherein the first electrode is disposed in the through-hole, and the threshold switch material layer is disposed on the substrate and the first electrode; A dielectric coating layer covers the side surface of the entire assembly consisting of the stacked threshold switch material layer and the second electrode.

5. The threshold switching device according to claim 3 or 4, characterized in that, The material of the first electrode is selected from at least one of W, TiW, TiN, and TiSiN.

6. The threshold switching device according to claim 3 or 4, characterized in that, The material of the second electrode is selected from at least one of W, TiW, and TiN.

7. The threshold switching device according to claim 3 or 4, characterized in that, The material of the dielectric coating layer is selected from at least one of SiO2 and Si3N4.

8. The threshold switching device according to claim 3 or 4, characterized in that, The thickness of the threshold switch material layer is 2~40 nm.

9. The threshold switching device according to claim 4, characterized in that, The substrate material is selected from at least one of SiO2 and Si3N4.

10. A method for fabricating a threshold switching device, characterized in that, Including the following steps: Provide the first electrode; A threshold switching material layer is formed on the first electrode, wherein the material of the threshold switching material layer includes the threshold switching material according to claim 1; A second electrode is formed on the threshold switching material layer.

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