Self-rectifying memristor and preparation method and application thereof

Abstract

This invention belongs to the field of semiconductor device technology, and discloses a self-rectifying memristor, its fabrication method, and its application. The memristor includes a bottom electrode, a resistive switching layer, an interface oxide layer, and a top electrode. The resistive switching layer is an inorganic molecular crystal thin film; the top electrode is a thin film of an active metal, alloy, or its compound with oxygen affinity; the interface oxide layer is formed in situ by an oxidation reaction between the active element in the top electrode and the resistive switching layer, and it is used to adjust the interface barrier between the top electrode and the resistive switching layer, and to provide a controllable oxygen vacancy source for the resistive switching process. The resistive switching layer regulates the oxygen vacancy migration behavior and the evolution of the conductive channel, causing a gradual change in the conductivity state, thus achieving self-rectification characteristics and linear conductivity control capability.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, and more specifically, relates to a self-rectified memristor, its preparation method and application. Background Technology

[0002] As the fourth fundamental circuit element after resistors, capacitors, and inductors, memristors have demonstrated significant application potential in non-volatile memory, neuromorphic computing, and in-memory computing systems since their inception. Memristors can control their internal conductivity state through applied electrical signals, achieving continuous or discrete changes in resistance, thereby enabling information storage and computation. Compared to the traditional von Neumann architecture's separation of storage and computation, memristor-based in-memory computing devices can significantly reduce data transfer energy consumption and improve system computational efficiency, thus attracting widespread attention in novel neuromorphic computing hardware and edge intelligence systems.

[0003] In existing memristor research, self-rectified memristors have attracted significant attention due to their substantial asymmetry in forward and reverse current responses. Self-rectification enables selective current regulation within the device, effectively suppressing sneak path currents in cross-array structures and improving the integration density and readout accuracy of large-scale device arrays. Currently, the main mechanisms achieving self-rectification include interface Schottky barrier modulation, asymmetric growth during electrochemical metallization, and spatial asymmetry in ion migration processes, making them valuable for applications in neuromorphic computing and high-density storage.

[0004] However, existing memristor devices generally suffer from strong nonlinearity in conductance updates during simulated conductance control, especially in multi-level weight adjustment processes. Conductance changes often exhibit abrupt or exponential evolution characteristics, making it difficult to achieve highly precise, linearly adjustable weight updates. This nonlinearity leads to the accumulation of weight update errors during neural network training, reducing algorithm convergence efficiency and recognition accuracy. Therefore, achieving continuous, repeatable, and highly linear control of the conductance state while maintaining self-rectification characteristics has become a crucial technical requirement in current memristor research and device engineering. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a self-rectified memristor, its preparation method and application, which aims to solve the problems of discontinuous conductance state control and weak self-rectification capability of existing memristors, resulting in low linearity.

[0006] To achieve the above objectives, according to one aspect of the present invention, a self-rectified memristor is provided, the self-rectified memristor comprising, from bottom to top, a bottom electrode, a resistive switching layer, an interface oxide layer, and a top electrode; the resistive switching layer is an inorganic molecular crystal thin film; the top electrode is a thin film of an active metal, alloy, or compound thereof with oxygen affinity; the interface oxide layer is formed in situ by an oxidation reaction occurring when an active element in the top electrode comes into contact with the resistive switching layer, and it is used to adjust the interface barrier between the top electrode and the resistive switching layer, and to provide a controllable oxygen vacancy source for the resistive switching process.

[0007] Furthermore, the material of the inorganic molecular crystal thin film is either Sb2O3 or As2O3.

[0008] Furthermore, the active metal with oxygen affinity is any one of Ti, Ta, Hf, Zr or Nb, used to react with the resistive switching layer to form an interfacial oxide layer.

[0009] Furthermore, the active metal alloy with oxygen affinity contains two or more of Ti, Ta, Hf, Zr, and Nbt, with the atomic proportion of any one dopant being greater than 5%.

[0010] Furthermore, the interface oxide layer is a metal oxide layer formed by the oxidation of active metal elements Ti, Ta, Hf, Zr or Nb, including TiO2. x TaO x HfO x ZrO x or NbO x One or more of them.

[0011] Furthermore, the thickness of the top electrode is 5 nm-200 nm.

[0012] The present invention also provides a method for fabricating the self-rectified memristor as described above, the method comprising the following steps: (1) Deposit a bottom electrode on the substrate; (2) An inorganic molecular crystal thin film is prepared on the bottom electrode to form a resistive switching layer; (3) Anneal the resistive switching layer to control the oxygen content and defect state on the surface of the resistive switching layer; (4) A thin film of an active metal, alloy or its compound with oxygen affinity is deposited on the resistive switching layer to form a top electrode; the material of the top electrode undergoes an interfacial oxidation reaction after contacting the resistive switching layer, and an interfacial oxide layer is spontaneously formed.

[0013] Furthermore, the annealing process is carried out in oxygen or an oxygen-containing atmosphere, the annealing temperature is controlled at 100℃-200℃, and the annealing time is 1 min-30 min.

[0014] Furthermore, both the top electrode and the bottom electrode are prepared by thermal evaporation deposition, electron beam evaporation deposition, or magnetron sputtering deposition.

[0015] The present invention also provides an application of the self-rectified memristor described above in non-volatile memory, neuromorphic computing, and in-memory computing systems.

[0016] In summary, compared with the prior art, the self-rectified memristor, its fabrication method, and its application provided by this invention have the following beneficial effects: 1. The interface oxide layer is formed in situ by the oxidation reaction between the active element in the top electrode and the resistive switching layer. It is used to adjust the interface barrier between the top electrode and the resistive switching layer and to provide a tunable oxygen vacancy source for the resistive switching process. Based on the structural characteristics of inorganic molecular crystals, the resistive switching layer regulates the migration behavior of oxygen vacancies and the evolution of the conductive channel, so that the conductivity state exhibits a gradual change. The top electrode layer, the interface oxide layer, and the resistive switching layer work together to realize the self-rectification characteristics and linear conductivity control capability of the memristor.

[0017] 2. This invention employs inorganic molecular crystals as the resistive switching layer material of a self-rectified memristor. Utilizing the ordered molecular arrangement and weak intermolecular coupling interactions, it provides a stable and repeatable evolutionary path for oxygen vacancy migration. This memristor effectively mitigates the abrupt conductance transitions caused by random defect aggregation and concentrated local electric fields in traditional oxide materials, allowing the memristor's conductance to evolve gradually with the external field. The memristor exhibits excellent linear fitting characteristics during multi-level conductance updates, thereby enabling more accurate simulation weight mapping, reducing accumulated errors in neural network calculations, and improving model training efficiency and recognition accuracy.

[0018] 3. This invention eliminates the need for an additional interface modification layer. Instead, it utilizes the spontaneous oxidation reaction between the oxygen-affinity active metal top electrode and the resistive switching layer to construct an interface oxide layer in situ at their interface, achieving synergistic control of the interface structure and resistive switching characteristics. This interface oxide layer optimizes the bandgap matching between the top electrode and the resistive switching layer, adjusts the carrier injection efficiency and interface barrier height, and effectively improves the rectification performance of the memristor. The memristor exhibits low reverse leakage current, effectively reducing leakage current interference caused by non-gated devices, improving array operational stability and read / write accuracy, and providing a reliable device foundation for high-density memristor array integration.

[0019] 4. This invention utilizes the synergistic effect between the top electrode, the interface oxide layer, and the inorganic molecular crystal resistive switching layer to achieve comprehensive control over the carrier transport and defect evolution processes within the device. This synergistic control mechanism effectively reduces the randomness in the resistive switching process, improves the consistency and repeatability of device state transitions, and enables the memristor to possess excellent cycle stability, device uniformity, and long-term operational reliability.

[0020] 5. This invention introduces an active electrode material with oxygen affinity to form an asymmetric interface modulation effect between the top electrode and the resistive switching layer, thereby achieving the self-rectification characteristics of the device, effectively suppressing reverse leakage current, improving the anti-crosstalk capability of the device in the cross array structure, and enhancing the integration scalability and read / write stability of the device array.

[0021] 6. The self-rectified memristor provided by the present invention has good conductance modulation characteristics and exhibits excellent linear fitting characteristics in the process of multi-level conductance update, thereby enabling more accurate simulation weight mapping, reducing the cumulative error in neural network calculation, and improving model training efficiency and recognition accuracy.

[0022] 7. The device structure of the present invention is simple and the fabrication process is highly compatible. It can be fabricated on a large scale using conventional thin film deposition processes, has good process repeatability, and can be applied to large-scale, high-density two-dimensional or three-dimensional integrated arrays, making it suitable for widespread application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a self-rectified memristor provided in an embodiment of the present invention; Figure 2 yes Figure 1 A flowchart of the fabrication method of the self-rectified memristor; Figure 3 yes Figure 1 The current-voltage DC characteristic curve of the self-rectified memristor in the diagram; Figure 4 yes Figure 1 The continuous forward direction of the self-rectified memristor in I - V Scan curve graph; Figure 5 yes Figure 1 Pulse conductance response diagram of the self-rectified memristor in the diagram; Figure 6 yes Figure 1 The results of the durability test for linear modulation periodic variation are shown in the figure. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] This invention provides a self-rectifying memristor, comprising, from bottom to top, a bottom electrode, a resistive switching layer, an interface oxide layer, and a top electrode. The resistive switching layer is an inorganic molecular crystal thin film; the top electrode is a thin film of an active metal, alloy, or its compound with oxygen affinity; the interface oxide layer is formed in situ by an oxidation reaction between the active element in the top electrode and the resistive switching layer, serving to regulate the interfacial barrier between the top electrode and the resistive switching layer and providing a tunable oxygen vacancy source for the resistive switching process. Based on the structural characteristics of inorganic molecular crystals, the resistive switching layer regulates the oxygen vacancy migration behavior and the evolution of the conductive channel, resulting in a gradual change in conductivity. The top electrode, the interface oxide layer, and the resistive switching layer work synergistically to achieve the self-rectifying characteristics and linear conductivity control capability of the memristor.

[0026] The inorganic molecular crystal film is made of either Sb₂O₃ or As₂O₃.

[0027] An active metal with oxygen affinity, such as Ti, Ta, Hf, Zr, or Nb, is used to react with the resistive switching layer to form an interfacial oxide layer.

[0028] Active metal alloys with oxygen affinity contain two or more of Ti, Ta, Hf, Zr, and Nbt, with the atomic proportion of any one dopant component being greater than 5%.

[0029] Compound thin films of active metals with oxygen affinity, wherein the material is any one of TiN, TaN, HfN, ZrN or NbN.

[0030] The interface oxide layer is a metal oxide layer formed by the oxidation of active metal elements Ti, Ta, Hf, Zr or Nb, including TiO2. x TaO x HfO x ZrO x or NbO x One or more of them.

[0031] The thickness of the top electrode is 5 nm to 200 nm. The work function of the bottom electrode is greater than that of the top electrode, and it includes any one of Pt, Au, and Pd.

[0032] The memristor described herein employs an inorganic molecular crystal thin film as the resistive switching layer and an oxygen-affinity active conductive material or its compound thin film as the top electrode material. By regulating the interfacial interaction between the top electrode and the resistive switching layer, asymmetric control of the charge transport process is achieved, thereby endowing the device with self-rectification characteristics and promoting the continuous tunability and stable evolution of the conductance state, enabling the device to exhibit high conductivity and multi-level storage capability. The memristor provided by this invention has a simple structure, strong compatibility with fabrication processes, and is conducive to high-density integrated applications, and can effectively improve the signal control accuracy and operational reliability of in-memory computing devices.

[0033] The present invention also provides a method for fabricating the self-rectified memristor as described above, the method comprising the following steps: (1) Deposit a bottom electrode on the substrate; (2) An inorganic molecular crystal thin film is prepared on the bottom electrode to form a resistive switching layer; (3) Anneal the resistive switching layer to control the oxygen content and defect state on the surface of the resistive switching layer; (4) A thin film of an active metal, alloy or its compound with oxygen affinity is deposited on the resistive switching layer to form a top electrode; the material of the top electrode undergoes an interfacial oxidation reaction after contacting the resistive switching layer, and an interfacial oxide layer is spontaneously formed.

[0034] The resistive switching layer was prepared by thermal evaporation deposition.

[0035] The annealing process is carried out in oxygen or an oxygen-containing atmosphere, with the annealing temperature controlled at 100℃-200℃ and the annealing time being 1 min-30 min.

[0036] Both the top electrode and the bottom electrode are prepared by thermal evaporation deposition, electron beam evaporation deposition, or magnetron sputtering deposition.

[0037] This invention also provides the application of the self-rectified memristor described above in non-volatile memory, neuromorphic computing, and in-memory computing systems.

[0038] The present invention will be further described in detail below with reference to specific embodiments.

[0039] Example 1 This embodiment 1 provides a self-rectifying device, the structure of which is as follows: Figure 1 As shown, the top electrode is a Ti thin film, the resistive switching layer is an Sb2O3 thin film, and the bottom electrode is an Au thin film.

[0040] The fabrication process of the self-rectifier device in Example 1 is as follows: Figure 2 As shown, its preparation method includes the following steps: (1) A silicon wafer was used as the substrate, and the bottom electrode pattern was prepared on the substrate by electron beam lithography. PMMA was used as the photoresist, and after spin coating, it was baked at 150 °C for 5 minutes. After exposure, the sample was immersed in the developer for 5-10 seconds, then immersed in the fixer for 10 seconds and dried with a nitrogen gun.

[0041] (2) A 5 nm Cr thin film was pre-deposited on the bottom electrode pattern prepared in step (1) using thermal evaporation deposition to improve the adhesion between the bottom electrode and the substrate, followed by the deposition of a 10 nm Au thin film as the bottom electrode. The process conditions were: Cr or Au particles as the evaporation source, nitrogen as the evaporation atmosphere, evaporation rate of 0.2 Å / s, and chamber pressure less than 8 × 10⁻⁶. -4 Pa. After coating, the sample with the bottom electrode is placed in acetone and heated to 70 °C, then soaked for 20 min to complete the removal of the adhesive.

[0042] (3) A layer of Sb₂O₃ was deposited on the bottom electrode as a resistive switching layer using a thermal evaporation deposition method. The thickness of the Sb₂O₃ film was 20 nm. The process conditions were: Sb₂O₃ powder was used as the evaporation source, nitrogen was used as the evaporation atmosphere, the evaporation rate was 0.1 Å / s, and the chamber pressure was less than 8 × 10⁻⁶. -4 Pa.

[0043] (4) The top electrode pattern is prepared on the Sb2O3 resistive switching layer by electron beam lithography, and the process conditions are the same as in step (2).

[0044] (5) A Ti thin film with a thickness of 20 nm was deposited on the top electrode pattern prepared in step (4) using thermal evaporation deposition. The process conditions were as follows: Ti powder was used as the evaporation source, nitrogen was used as the evaporation atmosphere, the evaporation rate was 0.1 Å / s, and the chamber pressure was less than 8 × 10⁻⁶. -4 Pa.

[0045] (6) A thin Au film with a thickness of 40 nm was deposited on the top electrode prepared in step (5) using thermal evaporation deposition. The process conditions were: Au particles as the evaporation source, nitrogen as the evaporation atmosphere, evaporation rate of 0.2 Å / s, and chamber pressure less than 8 × 10⁻⁶. 4 Pa. After coating, the sample with the top electrode deposited is placed in acetone, and the acetone is heated to 70 °C and soaked for 20 min to complete the removal of the adhesive, thus obtaining the memristor.

[0046] Results Analysis In this embodiment 1, the current-voltage relationship of the memristor I - V DC characteristic curve as shown Figure 3As shown. During testing, the top electrode of the device was grounded, and a bias voltage was applied to the bottom electrode, achieving 100 cyclic scans from -3 V to 3 V. The results show that when a positive bias voltage is applied, the device current gradually increases with the voltage up to 10. -6 The current transitions to the on-state at the order of A. When a negative bias is applied, the device current remains at 10 due to the high potential barrier between the bottom electrode and Sb₂O₃. -12 Level A effectively suppresses reverse leakage current. The device rectification ratio is as high as 5×10⁻⁶. 6 And in 100 cycles of testing I - V The curves highly overlap, indicating that it has excellent rectification characteristics and good cycle stability.

[0047] In this embodiment 1, the memristor is continuously positive I - V Scan curve as Figure 4 As shown in the figure. During the test, a continuous forward voltage scan within the range of 0-4 V was applied to the device, and a total of 30 cycles of testing were performed. The results show that as the number of scans increases, the device response current gradually increases, with an overall increase of more than 30 times, corresponding to a continuous enhancement and adjustable evolution of the conductance state. This stable and consistent conductance change behavior can effectively simulate the dynamic update process of synaptic weights, thus verifying the device's ability in continuous conductance control and simulated weight storage.

[0048] The pulse conductance response diagram of the memristor in this embodiment 1 is as follows: Figure 5 As shown. During the test, 4000 periodic electrical pulses with the same amplitude and width were applied to the device, and the change in its current response under the pulses was detected. The results show that with the continuous application of pulses, the device current exhibits a stable and approximately linear increasing trend, corresponding to a continuously adjustable enhancement process of the conductance state. Its dynamic control range can be approximately equivalent to a 12-bit resolution level. Linear fitting analysis of the curve yields the linearity R... 2 The value of 0.99915 indicates that the device has excellent linear conductance control characteristics.

[0049] In Example 1, the durability test of the memristor's linear modulation periodic variation is as follows: Figure 6 As shown. Within each cycle, 200 positive pulses are first applied to the device, causing its conductance to gradually increase linearly. Then, 200 negative pulses are applied, causing it to rapidly decay to a high-resistance state, thus completing one full "enhancement-suppression" process. This is repeated for a total of 250 cycles (corresponding to approximately 1 × 10⁻⁶). 5During the testing process (within one pulse), the device exhibited minimal inter-cycle fluctuations, with no significant performance degradation or fluctuations observed, indicating excellent cyclic stability and reliability. These results demonstrate that the memristor maintains stable conductance control even during long-term, repetitive linear weight updates, showing great application potential in analog synaptic weight modulation and neuromorphic computing.

[0050] Example 2 This embodiment 2 uses the same steps as embodiment 1 to prepare a self-rectifying device. The difference from embodiment 1 is that the top electrode is a Ta metal thin film with a thickness of 40 nm deposited by magnetron sputtering.

[0051] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-rectified memristor, characterized in that: The self-rectified memristor includes, from bottom to top, a bottom electrode, a resistive switching layer, an interface oxide layer, and a top electrode. The resistive switching layer is an inorganic molecular crystal thin film. The top electrode is an active metal, alloy, or compound thin film with oxygen affinity. The interface oxide layer is formed in situ by the oxidation reaction that occurs when the active element in the top electrode comes into contact with the resistive switching layer. It is used to adjust the interface barrier between the top electrode and the resistive switching layer and to provide a controllable oxygen vacancy source for the resistive switching process.

2. The self-rectified memristor as described in claim 1, characterized in that: The inorganic molecular crystal film is made of either Sb₂O₃ or As₂O₃.

3. The self-rectified memristor as described in claim 1, characterized in that: An active metal with oxygen affinity, such as Ti, Ta, Hf, Zr, or Nb, is used to react with the resistive switching layer to form an interfacial oxide layer.

4. The self-rectified memristor as described in claim 1, characterized in that: Active metal alloys with oxygen affinity contain two or more of Ti, Ta, Hf, Zr, and Nbt, with the atomic proportion of any one dopant component being greater than 5%.

5. The self-rectified memristor as described in any one of claims 1-4, characterized in that: The interface oxide layer is a metal oxide layer formed by the oxidation of active metal elements Ti, Ta, Hf, Zr or Nb, including TiO2. x TaO x HfO x ZrO x or NbO x One or more of them.

6. The self-rectified memristor as described in any one of claims 1-4, characterized in that: The thickness of the top electrode is 5 nm to 200 nm.

7. A method for fabricating a self-rectified memristor according to any one of claims 1-6, characterized in that, The method includes the following steps: (1) Deposit a bottom electrode on the substrate; (2) An inorganic molecular crystal thin film is prepared on the bottom electrode to form a resistive switching layer; (3) Anneal the resistive switching layer to control the oxygen content and defect state on the surface of the resistive switching layer; (4) A thin film of an active metal, alloy or its compound with oxygen affinity is deposited on the resistive switching layer to form a top electrode; the material of the top electrode undergoes an interfacial oxidation reaction after contacting the resistive switching layer, and an interfacial oxide layer is spontaneously formed.

8. The method for fabricating a self-rectified memristor as described in claim 7, characterized in that: The annealing process is carried out in oxygen or an oxygen-containing atmosphere, with the annealing temperature controlled at 100℃-200℃ and the annealing time being 1 min-30 min.

9. The method for fabricating a self-rectified memristor as described in claim 7, characterized in that: Both the top electrode and the bottom electrode are prepared by thermal evaporation deposition, electron beam evaporation deposition, or magnetron sputtering deposition.

10. The application of a self-rectified memristor according to any one of claims 1-6 in non-volatile memory, neuromorphic computing, and in-memory computing systems.

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