Amorphous tungsten oxide film simulation type resistance change memristor and preparation method and application thereof

Abstract

The invention discloses an amorphous tungsten oxide film simulation type resistance change memristor and a preparation method and application thereof, and belongs to the technical field of nonvolatile memories and neural network computing. The method comprises the following steps: firstly, depositing a first conductive film on an insulating substrate to serve as a bottom electrode of the analog resistive memristor; a physical vapor deposition method is adopted to grow an amorphous tungsten oxide thin film with the oxygen defect content changing in a gradient mode, and the amorphous tungsten oxide thin film serves as a resistance change medium storage layer of the simulation type resistance change memristor; and finally, depositing a second conductive thin film as an upper electrode to obtain the amorphous tungsten oxide thin film simulation type resistance change memristor. The resistive random access memory is simple in process, low in cost, high in controllability, easy to produce on a large scale and high in stability, oxygen vacancies distributed in the resistive random access memory layer in a gradient mode form or break a conductive channel by regulating and controlling voltage, simulated gradual change of resistive random performance is achieved, and reliability is high. The method has a wide market application prospect in the field of neural network calculation.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-volatile memory and neural network computing, and in particular relates to an amorphous tungsten oxide thin film analog resistive memristor and a preparation method and application thereof. Background Art

[0002] Memristors based on the resistive switching effect have the advantages of simple structure, high storage density, fast read and write speed, low power consumption and good CMOS compatibility, and are considered to be the most promising next-generation non-volatile memory. In particular, the resistance gradient behavior of resistive memristors under electrical stimulation is extremely similar to the behavior of biological synapses, so they are considered to be one of the most promising devices for realizing neural network hardware. The human brain relies on a large number of synapses and neurons to perform learning and memory functions, and can process and store massive amounts of information in parallel with extremely low energy consumption. Its information processing efficiency far exceeds that of current general-purpose computers. Synapses are the basic units responsible for signal modulation and transmission in the human brain. They transmit signals from preneurons to postneurons through synaptic gaps, and complete information processing and storage functions at the same time. Therefore, the development of a device similar to biological synapses will provide important support for the development of neuromorphic computing. Memristors are highly similar to biological synapses in structure and information transmission methods, and are considered to be an ideal choice for simulating biological synapses.

[0003] Common resistive switching functional layers include metal oxides, such as TaO x , WO x , HfO x and TiO x etc.; perovskite-type multi-element oxides, such as SrTiO3 and BaTiO3; sulfides, such as Cu2S, MoS2 and WS2; nitrides, such as AlN and Si3N4. Among them, binary transition metal oxides can regulate the metal valence state by the oxygen atmosphere content during the growth process, so they have unique optoelectronic properties and are regarded as an ideal material system for the development of high-reliability memristors. In particular, tungsten oxide materials have the characteristics of easy regulation of oxygen ions / vacancies and are a typical transition metal oxide. Tungsten oxide has attracted widespread attention due to its high thermal stability, relatively narrow bandgap (2.6-2.8 eV) and excellent electrical properties. In recent years, memristors have been widely explored in bionic and computing fields such as machine vision, neural networks and image recognition. At present, memristor synaptic devices have been successfully applied to neuromorphic computing circuits to realize functions such as image recognition. However, the performance of such devices still needs to be improved, such as limited conductance range, asymmetric conductance response and insufficient stability. Therefore, further research on synaptic devices and optimization of their performance are of great practical significance. By constructing brain-like synaptic devices based on memristors, it is hoped that these technical challenges can be resolved, laying the foundation for achieving efficient and low-power neuromorphic computing.

[0004] In view of the defects of existing memristors such as limited conductance range, asymmetric conductance response and insufficient stability, there is an urgent need to find an analog resistive memristor and its preparation method with simple process, low cost, strong controllability and high stability, so as to overcome the defects of existing memristors such as limited conductance range, asymmetric conductance response and insufficient stability, and simulate the function of biological synapse to meet the needs of neuromorphic computing. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an amorphous tungsten oxide thin film analog resistive memristor and a preparation method and application thereof, so as to solve the technical problem that the existing resistive memristor with a single tungsten oxide thin film layer has poor analog resistive performance.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a method for preparing an amorphous tungsten oxide thin film analog resistive memristor, comprising the following steps: 1) depositing a first conductive film on an insulating substrate as a bottom electrode of an analog resistive memristor; 2) On the bottom electrode prepared in step 1), a physical vapor deposition method is used to grow an amorphous tungsten oxide film with a gradient oxygen defect content as a resistive medium storage layer of an analog resistive memristor; 3) Depositing a second conductive film on the resistive dielectric storage layer grown in step 2) as an upper electrode to obtain an amorphous tungsten oxide film analog resistive memristor.

[0007] Preferably, in step 1), the insulating substrate is a highly flat insulating substrate, and the highly flat insulating substrate is transparent glass or single crystal silicon grown with silicon oxide.

[0008] Preferably, in step 1), the bottom electrode is electrochemically inert indium tin oxide, high-purity gold, high-purity platinum or high-purity tungsten; the thickness of the bottom electrode is 30-300 nm.

[0009] Preferably, in step 2), the physical vapor deposition method is magnetron sputtering or pulsed laser deposition; the target material for depositing the amorphous tungsten oxide film with a gradient change in oxygen defect content is a high-purity metal tungsten target or a tungsten oxide ceramic target.

[0010] Preferably, in step 2), the resistive dielectric storage layer is composed of 3 to 10 layers of tungsten oxide with different oxygen defect contents; the oxygen defect content is controlled by adjusting the flow rate ratio of argon and oxygen to 30:(5 to 30).

[0011] Preferably, in step 2), the growth power of the amorphous tungsten oxide film with a gradient change in oxygen defect content is 30-150 W; the growth time is 3-30 min; the heating temperature is 50-500° C.; an argon-oxygen mixed gas is introduced during the growth process, and the total working pressure is 0.1-2 Pa.

[0012] Preferably, in step 2), the thickness of the amorphous tungsten oxide film with a gradient oxygen defect content is 50-500 nm.

[0013] Preferably, in step 3), the upper electrode is electrochemically inert indium tin oxide, high-purity gold, high-purity platinum or high-purity tungsten; the thickness of the upper electrode is 30-300 nm.

[0014] The present invention also discloses an amorphous tungsten oxide thin film analog resistive memristor, which is prepared by the above-mentioned method for preparing the amorphous tungsten oxide thin film analog resistive memristor, and comprises, from bottom to top, an insulating substrate, a bottom electrode, a resistive dielectric storage layer and an upper electrode; the resistive dielectric storage layer is an amorphous tungsten oxide thin film with a gradient change in oxygen defect content.

[0015] The present invention also discloses the application of the amorphous tungsten oxide thin film analog resistive memristor prepared by the preparation method of the amorphous tungsten oxide thin film analog resistive memristor in neural network calculation.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a method for preparing an amorphous tungsten oxide thin film analog resistive memristor. A high-stability conductive film of a certain thickness is deposited on an insulating substrate as the bottom electrode of the memristor, which is the basis for ensuring the stability and reliability of the electrical properties of the constructed memristor. The high-stability conductive film is used as the bottom electrode of the memristor, which is an important component for obtaining an excellent memristor. A physical vapor deposition method is used to deposit an amorphous tungsten oxide thin film with a gradient change in oxygen defect content on the bottom electrode to obtain a resistive dielectric storage layer. The physical vapor deposition method has good repeatability, and the prepared device has the advantage of high stability. A high-stability conductive film of a certain thickness is further deposited on the resistive dielectric storage layer as the upper electrode of the memristor to obtain an amorphous tungsten oxide thin film analog resistive memristor with a gradient change in oxygen defect content. The high-stability conductive film of a certain thickness is used as the upper electrode, which is an important component for further ensuring the stability of the memristor. The method disclosed by the invention has simple process, low cost, strong controllability, is easy to realize large-scale production, and the device has high stability, and has broad market application prospects in the field of neural network calculation. Amorphous tungsten oxide materials have high thermal stability, narrow bandgap, and excellent electrical properties. Amorphous tungsten oxide has a large number of oxygen vacancy defects, so it has great application potential in resistive switching devices based on oxygen vacancy migration. The current mainstream memristor with a single tungsten oxide film layer has poor analog resistive switching performance. The present invention uses an amorphous tungsten oxide film with a gradient change in oxygen defect content as the resistive switching functional layer of the memristor to realize a memristor that can simulate biological synapses, which has broad application prospects in neuromorphic computing and other aspects.

[0017] Furthermore, the present invention uses an insulating substrate with high flatness, such as transparent glass or single crystal silicon with a silicon oxide layer grown on the surface, to construct an analog resistive memristor. A substrate with high flatness can effectively ensure the surface flatness of subsequent conductive electrodes and functional layers, providing a solid foundation for the stability and reliability of device performance. At the same time, glass or silicon oxide is selected as the substrate material because of its extremely high resistivity, which can significantly reduce the impact of tiny leakage current on the performance of the memristor, thereby further improving the stability and reliability of the device. This design not only optimizes the device structure, but also lays a technical foundation for achieving efficient and reliable resistive performance.

[0018] Furthermore, the thickness of the bottom electrode and the upper electrode of the present invention is designed to be within the range of 30-300nm, and the electrode material is an electrochemically inert material, including indium tin oxide, high-purity gold, platinum and tungsten. An electrode thickness below 30nm may cause the device to fail easily due to breakdown during long-term testing, while a thickness exceeding 300nm will cause material waste. At the same time, due to increased internal stress, the adhesion between the electrode and the substrate and the dielectric layer may be weakened, thereby reducing the reliability of the device. The use of electrochemically inert materials as electrode materials can effectively reduce the interference of the electrode on the resistive switching performance and improve the stability and reliability of the memristor. By reasonably selecting the electrode thickness and material, the present invention achieves an optimized balance between device performance, cost and process, and provides support for highly stable and highly reliable memristors.

[0019] Further, the present invention optimizes the preparation process of the resistive functional layer, selects magnetron sputtering and pulsed laser deposition as physical vapor deposition methods, and is used to grow the tungsten oxide resistive functional layer. The target material used is a high-purity metal tungsten target or a tungsten oxide ceramic target. Compared with chemical vapor deposition, the physical vapor deposition method has significant advantages. The thin film prepared by the chemical vapor deposition method usually has poor continuity and high cost, and it is difficult to maintain the low-cost and high-performance advantages of the memristor. In addition, the functional layer grown by chemical vapor deposition is incompatible with the mainstream CMOS process, which further increases the manufacturing cost and complexity of the device. By adopting a high-purity metal tungsten target or a tungsten oxide ceramic target, combined with physical vapor deposition technology, the introduction of impurities in the resistive functional layer can be significantly reduced, thereby improving the purity and quality of the film. This preparation process can not only ensure the stability and consistency of the resistive functional layer, but also be compatible with the existing CMOS process, further reducing the production cost and improving the overall performance of the memristor.

[0020] Furthermore, the present invention forms an amorphous tungsten oxide dielectric layer with a gradient change of oxygen defects by growing 3 to 10 layers of tungsten oxide films with different oxygen defect contents, which is used to simulate the resistive switching function of the memristor. The oxygen defect content is achieved by adjusting the flow rate ratio of argon gas to oxygen, and the range is set to 30: (5~30). When the number of design layers is too small, the resistive switching performance of the memristor is mainly manifested as a sudden change in resistance, and it is difficult to show good simulated resistive switching characteristics; when the number of design layers is too large, although the performance improvement is reduced, the manufacturing cost and power consumption of the device are significantly increased, and the benefits are reduced. The range of 3-10 layers is selected to balance performance, power consumption and cost. Too low oxygen flow rate will significantly reduce device performance and may cause unstable resistive switching characteristics; too high oxygen flow rate may inhibit the normal growth of the film (for example, affecting the plasma ignition phenomenon), thereby reducing the reliability of the device. By accurately controlling the flow rate ratio of argon gas to oxygen, the oxygen content is reasonably adjusted to achieve the goal of optimizing device performance.

[0021] Furthermore, the growth power of the amorphous tungsten oxide resistive dielectric layer is controlled between 30-150W; power below 30W will significantly reduce the growth rate of the tungsten oxide film, which not only increases the production cycle but also increases the manufacturing cost; while power above 150W will increase the surface roughness of the film, thereby affecting the stability and performance of the analog memristor; therefore, setting the growth power optimization between 30-150W can ensure the surface quality and reliability of device performance while ensuring the film growth efficiency. The growth time of the dielectric layer is set to 3-30min; growth time below 3min will cause the dielectric layer thickness to be too thin, so that the resistive performance cannot be manifested; growth time exceeding 30min will cause the film to be too thick, requiring higher power to maintain the resistive performance, which not only increases the power consumption of the device but also reduces the efficiency. The heating temperature is 50~500℃. The density of the tungsten oxide film grown below this heating range is reduced, and the performance of the memristor deteriorates. The roughness of the functional layer film grown above this temperature range increases, and the reliability of the tungsten oxide memristor is reduced. During the growth process, an argon-oxygen mixed gas is introduced, and the total working pressure is controlled between 0.1-2Pa. When the gas pressure is lower than 0.1Pa, the thickness of the tungsten oxide film is low, resulting in reduced reliability of the constructed memristor performance; when the gas pressure is higher than 2Pa, the film thickness increases significantly, thereby increasing the power consumption of the memristor. By optimizing the gas pressure within the range of 0.1-2Pa, the film thickness and memristor performance can be effectively balanced, ensuring a larger storage window and lower power consumption.

[0022] Furthermore, the thickness of the amorphous tungsten oxide film with a gradient change in oxygen defect content of the present invention is controlled between 50-500nm. When it is lower than 50nm, although the analog memristor can simulate the performance of biological synapses, its stability and reliability are significantly reduced; when it is higher than 500nm, the storage window is reduced, and it is difficult to achieve excellent analog resistive switching performance. Therefore, optimizing the film thickness within the range of 50-500nm can not only ensure stability and reliability, but also achieve good analog resistive switching characteristics.

[0023] The present invention also discloses an amorphous tungsten oxide thin film analog resistive memristor prepared by the above-mentioned preparation method. By adjusting the flow rate ratio of argon gas to oxygen, the gradient-distributed oxygen vacancies in the resistive layer form or break conductive channels, thereby realizing the simulated gradual change of resistive performance and showing high reliability. The amorphous tungsten oxide thin film based on the gradient change of oxygen defects has an adjustable resistance state and can effectively simulate the changes in pre- and post-synaptic membrane potential of biological synapses. By adjusting the oxygen defect content and resistive properties, signal transmission and memory effects in neural networks can be realized, thereby improving the learning ability and adaptability of neural networks.

[0024] The present invention also discloses the application of the amorphous tungsten oxide thin film analog resistive memristor prepared by the above-mentioned preparation method in neural network computing. The analog memristor can not only realize the storage function of information, but also efficiently process data through the resistive mechanism. In the neural network, the resistance state change of the memristor can directly correspond to the activation state of the neuron, thereby effectively performing tasks such as weighted summation, activation and learning update. During the training process of the neural network, the analog memristor can automatically adjust its resistance value according to the input signal, simulate synaptic plasticity (such as long-term potentiation LTP and long-term depression LTD), and realize the learning and memory function of the network. The change of oxygen defect gradient makes the device have a richer dynamic response and can support complex learning tasks. In short, the application of amorphous tungsten oxide thin film analog memristor based on the gradient change of oxygen defect content in neural network computing provides strong support for the realization of efficient, low-power, brain-like computing, and promotes the further development of artificial intelligence hardware. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of an amorphous tungsten oxide thin film analog resistive memristor manufactured in Embodiment 1 of the present invention; Figure 2 A logarithmic current-voltage curve diagram of an amorphous tungsten oxide thin film analog resistive memristor prepared in Embodiment 1 of the present invention; Figure 3 This is a cycle characteristic diagram of an amorphous tungsten oxide thin film analog resistive memristor obtained by implementation 1 of the present invention; Figure 4 This is a retention characteristic diagram of an amorphous tungsten oxide thin film analog resistive memristor obtained by implementation 1 of the present invention; Figure 5 The long-term potentiation (LTP) and long-term depression (LTD) diagrams of an amorphous tungsten oxide thin film analog resistive memristor prepared in embodiment 1 of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0028] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0029] In the present invention, unless otherwise specified, percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0030] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0031] In the present invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been listed in this document, and "6~22" is just an abbreviation of these numerical combinations.

[0032] The “range” disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.

[0033] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0034] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0035] Unless otherwise specified, the professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content may also be applied to the present invention.

[0036] The present invention provides a method for preparing an amorphous tungsten oxide thin film analog resistive memristor, comprising the following steps: 1) Depositing a conductive film of a certain thickness on a highly flat insulating substrate as the bottom electrode of the analog resistive memristor; 2) On the bottom electrode prepared in step 1), an amorphous tungsten oxide film with a gradient oxygen defect content is grown by physical vapor deposition as a resistive medium storage layer of a simulated memristor; 3) On the resistive medium storage layer grown in step 2), a conductive film is deposited as an upper electrode to obtain an amorphous tungsten oxide film analog resistive memristor. In step 1), the highly flat insulating substrate is transparent glass or single crystal silicon grown with silicon oxide. Preferably, the highly flat insulating substrate is single crystal silicon grown with silicon oxide.

[0037] The thickness of the bottom electrode is between 30 and 300 nm, and preferably, the thickness of the bottom electrode is 120 nm.

[0038] The bottom electrode material is electrochemically inert indium tin oxide, high-purity gold, high-purity platinum or high-purity tungsten. Preferably, the bottom electrode material is electrochemically inert high-purity platinum.

[0039] In step 2), the physical vapor deposition method is magnetron sputtering or pulsed laser deposition. Preferably, the physical vapor deposition method is magnetron sputtering; The target material for depositing the amorphous tungsten oxide film is a high-purity metal tungsten target material or a tungsten oxide ceramic target material. Preferably, the target material for depositing the amorphous tungsten oxide film is a high-purity metal tungsten target material.

[0040] The amorphous tungsten oxide dielectric resistive switching functional layer with a gradient change in oxygen defect content is composed of 3 to 10 layers of tungsten oxide with different oxygen defect contents. Preferably, the amorphous tungsten oxide dielectric resistive switching functional layer with a gradient change in oxygen defect content is composed of 5 layers of tungsten oxide with different oxygen defect contents.

[0041] The oxygen content is controlled by controlling the flow rate ratio of argon and oxygen in the range of 30:(5~30).

[0042] The growth power of the amorphous tungsten oxide resistive dielectric layer is 30~150W; the growth time of the dielectric layer is 3~30min; the heating temperature is 50~500℃; an argon-oxygen mixed gas is introduced during the growth process, and the total working pressure is 0.1~2Pa; preferably, the growth power of the amorphous tungsten oxide resistive dielectric layer is 100W; the growth time of the dielectric layer is 10min; the heating temperature is 250℃; an argon-oxygen mixed gas is introduced during the growth process, and the total working pressure is 1.75Pa.

[0043] The thickness of the amorphous tungsten oxide film with a gradient change in oxygen defect content is 50-500 nm. Preferably, the thickness of the amorphous tungsten oxide film with a gradient change in oxygen defect content is 300 nm.

[0044] In step 3), the thickness of the upper electrode is between 30 and 300 nm, and preferably, the thickness of the upper electrode is 120 nm.

[0045] The material of the upper electrode is electrochemically inert indium tin oxide, high-purity gold, high-purity platinum or high-purity tungsten. Preferably, the material of the upper electrode is electrochemically inert high-purity tungsten.

[0046] The present invention also discloses an amorphous tungsten oxide thin film analog resistive memristor prepared by the above preparation method, which comprises, from bottom to top, a highly flat insulating substrate, a bottom electrode, an amorphous tungsten oxide with a gradient change in oxygen defect content, and an upper electrode. The device has the advantages of simple process, low cost, strong controllability, easy large-scale production, and high stability, and has broad market application prospects in the field of neural network computing.

[0047] The present invention also discloses the application of the amorphous tungsten oxide thin film analog resistive memristor prepared by the above preparation method in neural network calculation. The change of oxygen defect gradient makes the device have richer dynamic response and can support complex learning tasks.

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0049] Example 1 A method for preparing an amorphous tungsten oxide thin film analog resistive memristor comprises the following steps: S1. On a single crystal silicon insulating substrate with highly flat silicon oxide growth, a high-purity platinum conductive film with a thickness of 120 nm is deposited as the bottom electrode of the analog resistive memristor; S2. On the prepared bottom electrode, five layers of amorphous tungsten oxide thin films with different oxygen defect content gradients are grown by magnetron sputtering physical vapor deposition. The flow rate ratios of argon and oxygen from top to bottom are 30:5, 30:10, 30:15, 30:20, and 30:25, which serve as the resistive dielectric storage layer of the simulated memristor. The growth power of each layer of amorphous tungsten oxide resistive dielectric layer is 100 W, the growth time of each layer is 2 min, the total growth time is 10 min, the heating temperature is 250 ° C, and argon and oxygen mixed gas is introduced during the growth process. The total working pressure is 1.75 Pa, and the thickness of the amorphous tungsten oxide film with oxygen defect content gradient is 300 nm.

[0050] S3. On the grown resistive dielectric storage layer, a tungsten conductive film with a thickness of 120 nm is deposited as an upper electrode to obtain an amorphous tungsten oxide film analog resistive memristor.

[0051] Figure 1 This is a schematic diagram of the structure of an amorphous tungsten oxide thin film analog resistive memristor prepared in Embodiment 1 of the present invention. As can be seen from the figure, the prepared oxygen defect content gradient-changing amorphous tungsten oxide thin film analog resistive memristor is composed of a bottom electrode, a resistive dielectric storage layer and an upper electrode from bottom to top, and the resistive dielectric storage layer is an amorphous tungsten oxide thin film with a gradient-changing oxygen defect content. Figure 2This is a logarithmic current-voltage curve of an amorphous tungsten oxide thin film analog resistive memristor obtained in Embodiment 1 of the present invention. It can be seen from the figure that during multiple DC cycle tests, the amorphous tungsten oxide thin film analog resistive memristor has stable analog characteristics and high stability.

[0052] Figure 3 This is a cycle characteristic diagram of an amorphous tungsten oxide thin film analog resistive memristor obtained in Embodiment 1 of the present invention. As can be seen from the figure, there is no sign of any decay in the switch resistance ratio after 100 cycles.

[0053] Figure 4 This is a retention characteristic diagram of an amorphous tungsten oxide thin film analog resistive memristor prepared in embodiment 1 of the present invention. It can be seen from the figure that after 10,000 seconds, the overall retention characteristic is good.

[0054] Figure 5 This is a diagram of the long-term potentiation (LTP) and long-term depression (LTD) of an amorphous tungsten oxide thin film analog resistive memristor prepared in Example 1 of the present invention. It can be seen that the conductivity response results have high symmetry and linearity.

[0055] Example 2 A method for preparing an amorphous tungsten oxide thin film analog resistive memristor comprises the following steps: S1. On a highly flat transparent glass insulating substrate, a 30 nm thick indium tin oxide conductive film is deposited as the bottom electrode of the analog resistive memristor; S2. On the prepared bottom electrode, five layers of amorphous tungsten oxide thin films with different oxygen defect content gradients are grown by physical vapor deposition. The flow rate ratios of argon and oxygen from top to bottom are 30:5, 30:10, 30:15, 30:20, and 30:25, which serve as the resistive medium storage layer of the simulated memristor. The growth power of each layer of the amorphous tungsten oxide resistive medium layer is 100 W, the growth time of each layer is 2 min, the total growth time is 10 min, the heating temperature is 250 ° C, and an argon-oxygen mixed gas is introduced during the growth process. The total working pressure is 1.75 Pa, and the thickness of the amorphous tungsten oxide film with oxygen defect content gradient is 300 nm.

[0056] S3. On the grown resistive dielectric storage layer, a 30 nm thick indium tin oxide conductive film is deposited as an upper electrode to obtain an amorphous tungsten oxide thin film analog resistive memristor.

[0057] In Example 2, the highly flat insulating substrate is transparent glass, the thickness of the bottom electrode and the upper electrode are both 30nm, and the electrode materials of the two are indium tin oxide; the physical vapor deposition method of pulsed laser deposition is adopted, and the target material is a tungsten oxide ceramic target. Compared with Example 1, the tungsten oxide analog memristor constructed using a transparent glass substrate and an indium tin oxide electrode has certain prospects in realizing photoelectric coupling regulation. The thickness of the electrode is relatively thin, and the analog resistance switching performance and stability of the prepared memristor are poor.

[0058] Example 3 A method for preparing an amorphous tungsten oxide thin film analog resistive memristor comprises the following steps: S1. On a single crystal silicon insulating substrate with highly flat silicon oxide growth, a high-purity gold conductive film with a thickness of 300 nm is deposited as the bottom electrode of the analog resistive memristor; S2. On the prepared bottom electrode, three layers of amorphous tungsten oxide films with different oxygen defect content gradients are grown by magnetron sputtering physical vapor deposition. The flow rate ratio of argon and oxygen from top to bottom is 30:5, 30:15, and 30:25, which serve as the resistive dielectric storage layer of the simulated memristor; the growth power of each layer of amorphous tungsten oxide resistive dielectric layer is 100 W, the growth time of each layer is 2 min, the total growth time is 10 min, the heating temperature is 250 ° C, and argon and oxygen mixed gas is introduced during the growth process. The total working pressure is 1.75 Pa, and the thickness of the amorphous tungsten oxide film with oxygen defect content gradient is 300 nm.

[0059] S3. On the grown resistive medium storage layer, a high-purity gold conductive film with a thickness of 300 nm is deposited as an upper electrode to obtain an amorphous tungsten oxide thin film analog resistive memristor.

[0060] In Example 3, the thickness of the upper electrode and the lower electrode is 300nm, the bottom electrode and the upper material are high-purity gold; three layers of amorphous tungsten oxide films with different oxygen defect content gradients are grown. Compared with Example 1, the preparation cost is higher due to the high cost of high-purity gold and the thicker electrode thickness; the simulated resistive switching performance of the prepared film is poor due to the simultaneous growth of three layers of amorphous tungsten oxide films with different oxygen defect content gradients.

[0061] Example 4 A method for preparing an amorphous tungsten oxide thin film analog resistive memristor comprises the following steps: S1. On a single crystal silicon insulating substrate with highly flat silicon oxide growth, a high-purity tungsten conductive film with a thickness of 120 nm is deposited as the bottom electrode of the analog resistive memristor; S2. On the prepared bottom electrode, 10 layers of amorphous tungsten oxide films with different oxygen defect content gradients are grown by magnetron sputtering physical vapor deposition, and the flow rate ratio of argon and oxygen from top to bottom is 30:5, 30:8; 30:10, 30:12; 30:15, 20:18; 30:20, 30:23, 30:25, 30:30, as the resistive medium storage layer of the simulated memristor; the growth power of each layer of amorphous tungsten oxide resistive medium layer is 100 W, the growth time of each layer is 2 min, the total growth time is 10 min, the heating temperature is 250 ° C, argon and oxygen mixed gas is introduced during the growth process, the total working pressure is 1.75 Pa, and the thickness of the amorphous tungsten oxide film with oxygen defect content gradient is 300 nm.

[0062] S3. On the grown resistive dielectric storage layer, a platinum conductive film with a thickness of 120 nm is deposited as an upper electrode to obtain an amorphous tungsten oxide thin film analog resistive memristor.

[0063] In Example 4, the bottom electrode is high-purity tungsten, and the upper electrode material is high-purity platinum; 10 layers of amorphous tungsten oxide films with different oxygen defect content gradients are grown. Compared with Example 1, although better simulated resistive switching performance is obtained by growing 10 layers of amorphous tungsten oxide films with different oxygen defect content gradients, the construction cost is higher.

[0064] Example 5 A method for preparing an amorphous tungsten oxide thin film analog resistive memristor comprises the following steps: S1. On a single crystal silicon insulating substrate with highly flat silicon oxide growth, a high-purity platinum conductive film with a thickness of 120 nm is deposited as the bottom electrode of the analog resistive memristor; S2. On the prepared bottom electrode, five layers of amorphous tungsten oxide thin films with different oxygen defect content gradients are grown by magnetron sputtering physical vapor deposition. The flow rate ratios of argon and oxygen from top to bottom are 30:5, 30:10, 30:15, 30:20, and 30:25, which serve as the resistive medium storage layer of the simulated memristor. The growth power of each layer of amorphous tungsten oxide resistive medium layer is 30 W, the growth time of each layer is 0.6 min, the total growth time is 3 min, the heating temperature is 50 ° C, argon and oxygen mixed gas is introduced during the growth process, the total working pressure is 0.1 Pa, and the thickness of the amorphous tungsten oxide film with oxygen defect content gradient is 50 nm.

[0065] S3. On the grown resistive dielectric storage layer, a tungsten conductive film with a thickness of 120 nm is deposited as an upper electrode to obtain an amorphous tungsten oxide film analog resistive memristor.

[0066] In Example 5, the growth conditions of the tungsten oxide film are at the lower limit of the range, and the prepared resistive dielectric storage layer is thin. Compared with Example 1, the stability of the device is poor due to the smaller thickness of the dielectric layer.

[0067] Example 6 A method for preparing an amorphous tungsten oxide thin film analog resistive memristor comprises the following steps: S1. On a single crystal silicon insulating substrate with highly flat silicon oxide growth, a high-purity platinum conductive film with a thickness of 120 nm is deposited as the bottom electrode of the analog resistive memristor; S2. On the prepared bottom electrode, five layers of amorphous tungsten oxide films with different oxygen defect content gradients are grown by magnetron sputtering physical vapor deposition. The flow rate ratios of argon and oxygen from top to bottom are 30:5, 30:10, 30:15, 30:20, and 30:25, which serve as the resistive medium storage layer of the simulated memristor. The growth power of each layer of amorphous tungsten oxide resistive medium layer is 150 W, the growth time of each layer is 6 min, the total growth time is 30 min, the heating temperature is 500 ° C, and argon and oxygen mixed gas is introduced during the growth process. The total working pressure is 2 Pa, and the thickness of the amorphous tungsten oxide film with oxygen defect content gradient is 500 nm.

[0068] S3. On the grown resistive dielectric storage layer, a tungsten conductive film with a thickness of 120 nm is deposited as an upper electrode to obtain an amorphous tungsten oxide film analog resistive memristor.

[0069] In Example 6, the growth conditions of the tungsten oxide film are at the upper limit of the range, and the prepared resistive dielectric storage layer is thicker than that in Example 1, resulting in poor simulated resistive performance due to the greater thickness of the dielectric layer.

[0070] In summary, the present invention discloses a method for preparing an amorphous tungsten oxide thin film analog resistive memristor, which has the following characteristics: 1) The preparation method of the present invention proposed by the present invention has simple process, low cost, strong controllability, is easy to achieve large-scale production, and the device has high stability.

[0071] 2) For the memristor with a single tungsten oxide resistive layer, the amorphous tungsten oxide thin film memristor with a gradient change in oxygen defect content exhibits stable analog resistive properties, especially a good ability to simulate synapses, which has important application prospects in the fields of neural network computing and image recognition.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an amorphous tungsten oxide thin film analog resistive memristor, characterized in that: The following steps are involved: 1) depositing a first conductive film on an insulating substrate as a bottom electrode of an analog resistive memristor; 2) On the bottom electrode prepared in step 1), a physical vapor deposition method is used to grow an amorphous tungsten oxide film with a gradient oxygen defect content as a resistive medium storage layer of an analog resistive memristor; 3) Depositing a second conductive film on the resistive dielectric storage layer grown in step 2) as an upper electrode to obtain an amorphous tungsten oxide film analog resistive memristor.

2. The method for preparing the amorphous tungsten oxide thin film analog resistive memristor according to claim 1, characterized in that: In step 1), the insulating substrate is a highly flat insulating substrate, and the highly flat insulating substrate is transparent glass or single crystal silicon grown with silicon oxide.

3. The method for preparing the amorphous tungsten oxide thin film analog resistive memristor according to claim 1, characterized in that: In step 1), the bottom electrode is electrochemically inert indium tin oxide, high-purity gold, high-purity platinum or high-purity tungsten; the thickness of the bottom electrode is 30-300 nm.

4. The method for preparing an amorphous tungsten oxide thin film analog resistive memristor according to claim 1, characterized in that: In step 2), the physical vapor deposition method is magnetron sputtering or pulsed laser deposition; the target material for depositing the amorphous tungsten oxide film with a gradient change in oxygen defect content is a high-purity metal tungsten target or a tungsten oxide ceramic target.

5. The method for preparing an amorphous tungsten oxide thin film analog resistive memristor according to claim 1, characterized in that: In step 2), the resistive dielectric storage layer is composed of 3 to 10 layers of tungsten oxide with different oxygen defect contents; the oxygen defect content is controlled by adjusting the flow rate ratio of argon and oxygen to 30: (5 to 30).

6. The method for preparing an amorphous tungsten oxide thin film analog resistive memristor according to claim 1, characterized in that: In step 2), the growth power of the amorphous tungsten oxide film with a gradient change in oxygen defect content is 30-150W; the growth time is 3-30min; the heating temperature is 50-500°C; an argon-oxygen mixed gas is introduced during the growth process, and the total working pressure is 0.1-2Pa.

7. The method for preparing an amorphous tungsten oxide thin film analog resistive memristor according to claim 1, characterized in that: In step 2), the thickness of the amorphous tungsten oxide film with a gradient oxygen defect content is 50-500 nm.

8. The method for preparing an amorphous tungsten oxide thin film analog resistive memristor according to claim 1, characterized in that: In step 3), the upper electrode is electrochemically inert indium tin oxide, high-purity gold, high-purity platinum or high-purity tungsten; the thickness of the upper electrode is 30-300 nm.

9. An amorphous tungsten oxide thin film analog resistive memristor, characterized in that: The device is manufactured by the method for preparing an amorphous tungsten oxide thin film analog resistive memristor as described in any one of claims 1 to 8, and comprises, from bottom to top, an insulating substrate, a bottom electrode, a resistive dielectric storage layer and an upper electrode; the resistive dielectric storage layer is an amorphous tungsten oxide thin film with a gradient change in oxygen defect content.

10. Application of the amorphous tungsten oxide thin film analog resistive memristor prepared by the method for preparing the amorphous tungsten oxide thin film analog resistive memristor according to any one of claims 1 to 8 in neural network calculation.

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