Resistive random access memory based on defect modulation and quantum conductance effect regulation and control method thereof

Abstract

The invention provides a defect modulation-based resistive random access memory and a quantum conductance effect regulation and control method thereof. The defect modulation-based resistive random access memory comprises a top electrode, a dielectric layer and a bottom electrode which are arranged in sequence, wherein one of the top electrode and the bottom electrode is an active metal layer, the other layer is an inert material layer, and the dielectric layer is a defect-modulated two-dimensional layered material layer; vacancy defects are arranged on the surface, close to one side of the active metal layer, of the dielectric layer; the vacancy defect is used for being matched with metal ions generated by the active metal layer to form a conductive channel for connecting the top electrode and the bottom electrode. By means of the method, defects can be introduced into the surface of the two-dimensional dielectric layer material close to one side of the active metal electrode, so that the forming position of a conductive channel is regulated and controlled, random migration of ions is limited, and effective regulation and control of the quantum conductivity effect are further achieved.

Description

Technical Field

[0001] The present invention relates to the field of nanotechnology and information storage technology, and more specifically, to a resistive random access memory based on defect modulation and a method for controlling the quantum conductivity effect thereof. Background Art

[0002] With the rapid development of intelligence and electronicization, the demand for high-density, low-power data storage has become increasingly prominent. The current mainstream memory (DRAM, SRAM, Flash) uses transistors as the main unit, and its size has approached the physical limit. Moore's Law is facing challenges.

[0003] As a new type of information device in the post-Moore era, resistive random access memory has the advantages of small size, low power consumption, high storage density, good compatibility with CMOS process and non-volatility. It is considered to be the device with the greatest potential to provide solutions for current massive data storage and achieve technological innovation. Generally, resistive random access memory adopts a simple sandwich structure. Through the external electric field, ions are induced to migrate and undergo redox reactions, and a nano-conductive channel connecting the top electrode and the bottom electrode can be formed in the dielectric layer. Controlling the reversible on and off of the nano-conductive channel can realize the switching of the device between high and low resistance states, and then the high and low resistance states are encoded as "0" and "1" respectively, thereby realizing the binary storage function of data.

[0004] At present, the channel size can be controlled by fine-tuning the application method and parameters of the external electric field. When the characteristic length of the conductive channel is equivalent to the mean free path of the conduction electrons, the electrons pass through the channel in a ballistic transport mode without scattering and collision, thus showing quantized conductivity behavior. Compared with traditional binary storage, the quantum conductivity effect is expected to realize the multi-value storage function of data, thereby further improving the storage density of the device.

[0005] However, the formation and breaking process of the resistive random access memory conductive channel is random, which seriously affects the stability of the device performance and limits the practical application of the quantum conductivity effect. Therefore, how to process the dielectric layer so that the metal ions can migrate in a controllable manner under the action of an external electric field, form a relatively stable conductive channel, obtain more quantum conductivity states, and prepare a resistive random access memory with good retention and cyclability is of great significance for realizing its multi-value storage function and meeting people's demand for high-density and high-performance storage. Summary of the invention

[0006] In view of the above problems, the present invention provides a resistive random access memory based on defect modulation and a method for regulating quantum conductivity effect thereof, so as to solve the problem that the formation and breaking processes of the conductive channel of the existing resistive random access memory are both random, thus affecting the stability of device performance.

[0007] The defect modulation-based resistive random access memory provided by the present invention comprises a top electrode, a dielectric layer and a bottom electrode arranged in sequence; wherein:

[0008] One of the top electrode and the bottom electrode is an active metal layer, the other is an inert material layer, and the dielectric layer is a defect-modulated two-dimensional layered material layer;

[0009] The dielectric layer is provided with vacancy defects on a surface close to the active metal layer;

[0010] The vacancy defects are used to cooperate with the metal ions generated by the active metal layer to form a conductive channel connecting the top electrode and the bottom electrode;

[0011] The size of the conductive channel is regulated by changing the external electric field and limiting the current, thereby obtaining a quantized conductivity step.

[0012] In addition, an optional technical solution is that the active metal material of the active metal layer includes at least one of Ag, Cu, and Ni.

[0013] In addition, an optional technical solution is that the inert material of the inert material layer includes at least one of Au, Pt, and graphite electrode.

[0014] In addition, an optional technical solution is that the material of the two-dimensional layered material layer includes at least one of transition metal chalcogenides, boron nitride, black phosphorus, graphene, and silicene; wherein,

[0015] The transition metal chalcogenides include MoS2, WS2, MoSe2, and WSe2.

[0016] In addition, an optional technical solution is that the preparation method of the top electrode and the bottom electrode includes at least one of magnetron sputtering, electroplating, pulsed laser deposition, physical and chemical vapor deposition, and molecular beam epitaxy.

[0017] In addition, an optional technical solution is that the preparation method of the dielectric layer includes at least one of a mechanical stripping method, a solution stripping method, an electrochemical method, a hydrothermal method, chemical vapor deposition, and chemical vapor transport.

[0018] In addition, an optional technical solution is that the vacancy defects are regulated by at least one of generating them during the preparation of the dielectric layer, performing plasma treatment after the preparation of the dielectric layer is completed, using TEM for electron beam irradiation to generate nanopores, particle bombardment, laser irradiation, and chemical treatment.

[0019] In addition, an optional technical solution is that the thickness of the two-dimensional layered material layer is in the range of 20 to 50 nm.

[0020] On the other hand, the present invention also provides a method for controlling the quantum conductivity effect of a resistive random access memory based on defect modulation, which is used to control the above-mentioned resistive random access memory based on defect modulation; wherein the method comprises:

[0021] A positive voltage is applied to the active metal layer, and the active metal is partially oxidized into metal ions, and migrates to the two-dimensional layered material layer under the action of the external electric field;

[0022] The metal ions occupy vacancy defects in the two-dimensional layered material layer and are reduced to metal atoms;

[0023] The metal atoms form a conductive channel connecting the top electrode and the bottom electrode, and the size of the conductive channel is regulated by changing the external electric field applied to the resistive random access memory and limiting the current to achieve a quantum conductance effect;

[0024] Applying a negative voltage to the active metal layer, the metal atoms forming the conductive path are oxidized into metal ions, and migrate toward the active metal layer under the action of the electric field, and the conductive path is broken;

[0025] The above process is repeated to achieve regulation of the quantum conductivity effect of the resistive memory.

[0026] In addition, an optional technical solution is that the external electric field control method includes DC scanning or pulse scanning.

[0027] Utilizing the above-mentioned defect-modulated resistive random access memory and its quantum conductivity effect control method, vacancy defects are set on the surface of the dielectric layer close to the active metal layer. The vacancy defects can provide migration sites for the metal ions generated by the active metal layer, thereby suppressing the randomness of the formation and disconnection of the conductive channel. The metal ions can realize controllable migration under the action of an external electric field to form a relatively stable conductive channel, thereby obtaining more quantum conductivity states, and preparing a resistive random access memory with good retention and cyclability, which can be applied to high-density storage, multi-valued logic, neuromorphic computing and other fields.

[0028] In order to achieve the above and related purposes, the present invention will describe its features in detail. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more clear and easy to understand. In the accompanying drawings:

[0030] Figure 1A schematic diagram of the structure of a resistive random access memory based on defect modulation according to an embodiment of the present invention;

[0031] Figure 2 1 is a device current-voltage (IV) curve of a dielectric layer of a resistive random access memory based on defect modulation according to an embodiment of the present invention after being surface treated to different degrees;

[0032] Figure 3 The device conductivity-voltage (GV) curves of the dielectric layer of the defect-modulated resistive random access memory according to an embodiment of the present invention after being surface-treated to different degrees;

[0033] Figure 4 4 is a curve showing the variation of the average number of quantum conductance steps with plasma processing power in a resistive random access memory based on defect modulation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is apparent that these embodiments may also be implemented without these specific details. In other examples, for ease of describing one or more embodiments, known structures and devices are shown in the form of block diagrams.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0036] It will be understood by those skilled in the art that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that the term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

[0037] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0038] In order to describe in detail the defect-modulated resistive random access memory and the method for controlling quantum conductivity effect thereof of the present invention, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0039] Figure 1 The schematic structure of a resistive random access memory based on defect modulation according to an embodiment of the present invention is shown.

[0040] like Figure 1 As shown, the defect-modulated resistive random access memory of an embodiment of the present invention comprises a top electrode, a dielectric layer and a bottom electrode which are sequentially arranged; wherein, one of the top electrode and the bottom electrode is arranged as an active metal layer, the other layer is arranged as an inert material layer, and the dielectric layer is located between the two and can be arranged as a defect-modulated two-dimensional layered material layer; in addition, vacancy defects are arranged on the surface of the dielectric layer close to the active metal layer, and the vacancy defects can provide migration sites for metal ions generated by the active metal layer, thereby forming a conductive channel connecting the top electrode and the bottom electrode, and the size of the conductive channel is controlled by changing the external electric field and limiting the current, thereby obtaining a quantized conductivity step, and the controllable migration of metal ions can be achieved through the vacancy defects, thereby improving the stability of the conductive channel.

[0041] Among them, the active metal material of the active metal layer includes at least one of Ag, Cu, and Ni; the inert material of the inert material layer includes at least one of Au, Pt, graphite electrode, etc.; the material of the two-dimensional layered material layer includes at least one of transition metal chalcogenides, boron nitride, black phosphorus, graphene, silicene, etc.; among them, transition metal chalcogenides include MoS2, WS2, MoSe2, WSe2, etc.

[0042] In addition, the active metal layer, dielectric layer, and inert material layer can all be in a thin film state. The thickness of the top electrode and the bottom electrode can ensure that they are conductive, and the thickness of the dielectric layer can ensure that it does not leak electricity. Vacancy defects are introduced into the surface of the dielectric layer close to the active metal layer to limit the formation position of the conductive channel and achieve effective regulation of the quantum conductivity effect. Among them, the preparation method of the top electrode and the bottom electrode includes one or a combination of magnetron sputtering, electroplating, pulsed laser deposition, physical and chemical vapor deposition, molecular beam epitaxy, etc.

[0043] Furthermore, the preparation method of the dielectric layer includes at least one of a mechanical stripping method, a solution stripping method, an electrochemical method, a hydrothermal method, a chemical vapor deposition method, a chemical vapor transport method, etc.; the control method of the vacancy defects may include generating them during the preparation of the dielectric layer, performing plasma treatment after the preparation of the dielectric layer is completed, using TEM for electron beam irradiation to generate nanopores, particle bombardment, laser irradiation, chemical treatment, etc.

[0044] By using the defect modulation-based resistive random access memory of the above-mentioned embodiment of the present invention, electrical performance testing can be performed using both direct current scanning and pulse scanning methods, and conductivity quantization behavior occurs during both positive and negative voltage scanning processes.

[0045] As a specific example, the method for preparing a resistive random access memory based on defect modulation according to an embodiment of the present invention may include the following steps:

[0046] 1. A 3nm thick Ti film is deposited on the silicon wafer substrate by electron beam evaporation as a transition layer, and then a 30nm thick Au layer is deposited as the bottom electrode;

[0047] 2. Using mechanical stripping method to transfer MoS2 with a thickness of 20-50 nm as a dielectric layer on the bottom electrode;

[0048] 3. Place the transferred MoS2 in a plasma cleaning machine and use the high-energy argon ions (Ar + ) sputters the surface of MoS2, which results in the loss of sulfur atoms and thus produces S vacancy defects on the surface of MoS2.

[0049] Among them, high-energy argon ions will also create a small amount of S vacancy defects inside MoS2, and the depth of the internal sulfur vacancies is positively correlated with the size of the plasma treatment parameters. Among them, different argon plasma RF powers are set, for example: 0W, 50W, 100W, 150W, and the treatment time is 30s. Compared with the case where the ratio of S atoms to Mo atoms is 1.85 at 0W, the ratio of S atoms to Mo atoms after argon plasma treatment at 50W, 100W, and 150W powers is reduced to 1.25, 1.21, and 1.19, respectively. Therefore, the concentration and depth of sulfur vacancy defects on the MoS2 surface can be controlled by controlling the plasma treatment parameters.

[0050] 4. Using electron beam evaporation with a thickness of 50 nm as the top electrode, the vacancy defects and dangling bonds generated by the loss of S atoms on the MoS2 surface will improve the bonding ability between Ag and the MoS2 surface.

[0051] In a specific embodiment of the present invention, the thickness of the two-dimensional layered material layer can be set to range from 20 to 50 nm.

[0052] In the application process of the resistive random access memory based on defect modulation in the embodiment of the present invention:

[0053] 1. The writing process includes: applying a positive voltage to the active metal electrode, the electrode material is partially oxidized into metal ions, and migrates to the two-dimensional layered dielectric material layer under the action of an external electric field, preferentially occupying the vacancy defect position, and accepting electrons from the inert material layer at the vacancy defect position and being reduced to metal atoms. With the continuous action of the electric field and the continuous accumulation of metal atoms, the metal atoms occupying the vacancy defect position eventually form a conductive channel connecting the top electrode and the bottom electrode. At this time, the resistive memory switches to a low resistance state, and the device will have multiple quantum conductivity states in this process;

[0054] 2. During the erasing process, a negative voltage is applied to the active metal electrode. The metal atoms that form the conductive channel will be oxidized into metal ions again. Under the action of the electric field, they migrate toward the active metal layer, breaking the conductive channel and returning the resistive memory to a high-resistance state.

[0055] It can be seen that by repeating the electrical operation process of steps 1 and 2 above, reversible regulation of the quantum conductivity effect of the resistive random access memory can be achieved.

[0056] In another embodiment, using the 1500 semiconductor parameter analyzer, the specific process of regulating the quantum conductance effect of the defect-modulated resistive memory of the embodiment of the present invention may include:

[0057] First, the bottom electrode Au was grounded, and a forward scanning voltage was applied to the top electrode Ag, and the limiting current was set to 350 μA. Figure 2 and Figure 3 They are the IV and GV curves of the resistive random access memory with the dielectric layer under different surface treatment conditions under the same external scanning voltage and limiting current.

[0058] It can be seen that the external voltage required for the resistive random access memory to form a conductive channel without surface plasma treatment is relatively large (about 0.44V) (e.g. Figure 2 (a) and Figure 3 (a)); after 50W plasma treatment, the resistive memory reaches the threshold required to form a conductive channel at a voltage of about 0.36V (as shown in Figure 2 (b) and Figure 3 (b)); In addition, after 100W plasma treatment, the device only needs about 0.13V to reach the conductance transition threshold (as shown in Figure 2 As shown in (c), as the positive voltage continues to increase, the metal atoms migrate and aggregate toward the bottom electrode, and the number and lateral size of the conductive channel expand, resulting in multiple quantum conductance steps before reaching the limiting current (such as Figure 3After the 150W plasma treatment, the threshold voltage at which the conductivity of the device begins to jump further decreases to about 0.024V (as shown in Figure 2 (d) and Figure 3 (d)).

[0059] The number of quantum conductance steps in the resistive memory without dielectric layer treatment (0W) and the resistive memory treated with plasma at power of 50W, 100W, and 150W respectively during the positive and negative voltage cycle scanning process is counted, as shown in Figure 2. Figure 4 As shown in FIG. 1 , as the plasma processing power increases, the average number of quantum conductance steps appearing in the resistive random access memory also gradually increases.

[0060] In addition, by applying a negative voltage to the Ag top electrode, the metal atoms in the conductive channel will gradually be oxidized and dissolved, and eventually the channel will break, and the quantum conductivity effect of the resistive memory can be effectively controlled by an external voltage.

[0061] According to the above results, the sulfur vacancy defects introduced on the surface and inside of MoS2 by argon plasma treatment provide preferred sites for the growth and electrical drift of electrode Ag atoms, effectively suppressing the randomness of the formation position of the conductive filaments, while making the conductive filaments more stable during formation and breaking, reducing the spontaneous relaxation process of ions, and achieving effective regulation of the quantum conductivity effect of resistive random access memory. The number of quantum conductivity steps increases, and with the increase of plasma treatment intensity, the device can reach higher states of quantum conductivity steps under the same limiting current.

[0062] Corresponding to the above-mentioned resistive random access memory based on defect modulation, the present invention further provides a method for controlling the quantum conductivity effect of a resistive random access memory based on defect modulation, which is used to control the above-mentioned resistive random access memory based on defect modulation; wherein the method comprises:

[0063] S100: applying a positive voltage to the active metal layer, the active metal is partially oxidized into metal ions, and migrates to the two-dimensional layered material layer under the action of an external electric field;

[0064] S200: metal ions occupy vacancy defects in the 2D layered material layer and are reduced to metal atoms;

[0065] S300: The metal atoms form a conductive channel connecting the top electrode and the bottom electrode, and the size of the conductive channel is regulated by changing the external electric field applied to the resistive random access memory and limiting the current to achieve a quantum conductance effect;

[0066] S400: applying a negative voltage to the active metal layer, the metal atoms forming the conductive channel are oxidized into metal ions, and migrate to the active metal layer under the action of the electric field, and the conductive channel is broken;

[0067] S500: Repeat the above process to achieve regulation of the quantum conductivity effect of the resistive memory.

[0068] Wherein, the external electric field control method includes direct current scanning or pulse scanning.

[0069] It should be noted that the embodiments of the method for controlling the quantum conductivity effect of a resistive random access memory based on defect modulation may refer to the description in the embodiments of the resistive random access memory based on defect modulation, which will not be described in detail here.

[0070] The defect-modulated resistive random access memory and the method for controlling quantum conductivity effect thereof according to the present invention have the following beneficial effects:

[0071] 1. Using two-dimensional layered materials as dielectric layers, the two-dimensional atomic plane in the vertical structure can effectively control the migration of metal ions and the rate of redox reactions, which is conducive to the precise control of quantized conductivity. Compared with unprocessed resistive random access memory, defect modulation can produce more quantum conductivity state steps;

[0072] 2. The defects in the dielectric layer of the resistive random access memory provide migration sites for active metal atoms, effectively suppressing the randomness of the formation and breakage of the conductive channel, reducing the spontaneous relaxation process of ions, and improving the relative stability of the conductive channel;

[0073] 3. The defects in the dielectric layer of the resistive random access memory can reduce the operating voltage of the device, which is beneficial to improving the cycle stability of the device, extending the life of the device, and reducing the energy consumption of the device.

[0074] As described above with reference to the accompanying drawings, the resistive random access memory based on defect modulation and the method for controlling the quantum conductivity effect thereof according to the present invention are described by way of example. However, those skilled in the art should understand that various improvements can be made to the resistive random access memory based on defect modulation and the method for controlling the quantum conductivity effect thereof proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A resistive random access memory based on defect modulation, characterized in that: It includes a top electrode, a dielectric layer and a bottom electrode arranged in sequence; wherein, One of the top electrode and the bottom electrode is an active metal layer, the other is an inert material layer, and the dielectric layer is a defect-modulated two-dimensional layered material layer; The dielectric layer is provided with vacancy defects on a surface close to the active metal layer; The vacancy defects are used to cooperate with the metal ions generated by the active metal layer to form a conductive channel connecting the top electrode and the bottom electrode; The size of the conductive channel is regulated by changing the external electric field and limiting the current, thereby obtaining a quantized conductivity step.

2. The defect modulation-based resistive random access memory according to claim 1, characterized in that: The active metal material of the active metal layer includes at least one of Ag, Cu and Ni.

3. The defect modulation-based resistive random access memory according to claim 1, characterized in that: The inert material of the inert material layer includes at least one of Au, Pt, and a graphite electrode.

4. The defect modulation-based resistive random access memory according to claim 1, characterized in that: The material of the two-dimensional layered material layer includes at least one of transition metal chalcogenides, boron nitride, black phosphorus, graphene, and silicene; wherein, The transition metal chalcogenides include MoS2, WS2, MoSe2, and WSe2.

5. The defect modulation-based resistive random access memory according to claim 1, characterized in that: The preparation method of the top electrode and the bottom electrode comprises at least one of magnetron sputtering, electroplating, pulsed laser deposition, physical and chemical vapor deposition, and molecular beam epitaxy.

6. The defect modulation-based resistive random access memory according to claim 1, characterized in that: The preparation method of the dielectric layer includes at least one of a mechanical stripping method, a solution stripping method, an electrochemical method, a hydrothermal method, a chemical vapor deposition method, and a chemical vapor transport method.

7. The defect modulation-based resistive random access memory according to claim 1, characterized in that: The vacancy defects are regulated by at least one of generating them during the preparation of the dielectric layer, performing plasma treatment after the preparation of the dielectric layer, using TEM to perform electron beam irradiation to generate nanopores, particle bombardment, laser irradiation, and chemical treatment.

8. The defect modulation-based resistive random access memory according to claim 1, characterized in that: The thickness of the two-dimensional layered material layer is in the range of 20 to 50 nm.

9. A method for controlling the quantum conductivity effect of a resistive random access memory based on defect modulation, characterized in that: Used to control the defect-modulated resistive random access memory according to any one of claims 1 to 8; wherein the method comprises: applying a positive voltage to the active metal layer, partially oxidizing the active metal into metal ions, and migrating to the two-dimensional layered material layer under the action of an external electric field; The metal ions occupy vacancy defects in the two-dimensional layered material layer and are reduced to metal atoms; The metal atoms form a conductive channel connecting the top electrode and the bottom electrode, and the size of the conductive channel is regulated by changing the external electric field applied to the resistive random access memory and limiting the current to achieve a quantum conductance effect; Applying a negative voltage to the active metal layer, the metal atoms forming the conductive path are oxidized into metal ions, and migrate toward the active metal layer under the action of the electric field, and the conductive path is broken; The above process is repeated to achieve regulation of the quantum conductivity effect of the resistive memory.

10. The method for controlling the quantum conductivity effect of a resistive random access memory based on defect modulation according to claim 9, characterized in that: The external electric field control method includes direct current scanning or pulse scanning.

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