A method for regulating the resistance transition behavior of niobium oxide film limited by current and application thereof

Abstract

This invention belongs to the field of functional oxide thin-film switches, specifically disclosing a method for controlling the resistance transition behavior of niobium oxide thin films by limiting current and its application. This invention adjusts the NbO... x The limiting current of the thin film ( I cc The size controls its switching behavior, when I cc At 5 mA and 10 mA, the device exhibits non-volatile resistive switching behavior and volatile resistive switching behavior, respectively; when the mA is increased... I cc At 50 mA, NbO x The non-volatile and volatile resistive behaviors occur simultaneously in NbO. x The device can exhibit 1S1R resistive switching behavior, and each resistive switching behavior of the device can be stably switched more than 100 times. The 1S1R resistive switching behavior of the present invention can suppress crosstalk current in the RRAM three-dimensional integrated structure during data reading. Therefore, the above-mentioned control method can be applied to threshold gating switches and also to resistive switching memories.

Description

Technical Field

[0001] This invention belongs to the field of functional oxide thin-film switches (resistive switching characteristics), specifically relating to a method for controlling the resistance switching behavior of a niobium oxide thin film by limiting current and its application in a three-dimensional stacked structure of a threshold gating switch or a resistive switching memory. Background Technology

[0002] The resistive switching phenomenon, characterized by a resistance change of several orders of magnitude before and after the transition (high resistance state HRS and low resistance state LRS), has been widely studied for its applications in information storage and digital switching. Resistive switching behavior can be categorized as volatile or non-volatile. Volatile resistive switching occurs when the voltage is removed, immediately returning the resistance to its stable state, such as in threshold selectors. Non-volatile resistive switching occurs when the voltage is removed, maintaining a low resistance state, such as in resistive random access memory (RRAM). Due to its simple two-terminal structure, RRAM devices can be integrated using a 4F architecture. 2 The cross-shaped array structure greatly improves information storage density, but the cross-shaped array structure has a serious crosstalk problem, which can easily cause misreading of information and severely limits the large-scale commercial application of RRAM.

[0003] Because Nb has multiple valence states, Nb 5+ Nb 4+ and Nb 2+ Single-component NbO2 or Nb2O5 are difficult to prepare, therefore, the NbO prepared in the existing technology is relatively simple. x It is generally composed of Nb₂O₅, NbO₂, and oxides with lower valence states. 4+ The corresponding oxide NbO2 exhibits volatile resistive switching characteristics due to its metal-insulator phase transition. 5+ The corresponding oxide, Nb₂O₅, typically exhibits non-volatile resistive switching characteristics. Therefore, the volatile resistive switching characteristics of NbO₂ can be used as a selector, and the non-volatile resistive switching characteristics of Nb₂O₅ can be used as a reverse resistive switching (RRAM) (these two have been extensively studied), or other methods can be employed to convert NbO₂ into a non-volatile resistive switching (RRAM) component. xThe simultaneous activation of two resistive switching properties of the material allows it to self-assemble into a Selector-RRAM (1S1R) device to suppress crosstalk current issues during data readout of the RRAM three-dimensional integrated structure (related reports are few). There are reports of connecting fabricated Pt / NbO2 / Pt devices and Pt / Nb2O5 / Pt devices in series to form a 1S1R device, and the Nb2O5 / NbO2 bilayer structure device shows a stable cycle count of approximately 20 (X. Liu, et al. Co-occurrence of threshold switching and memory switching in Pt / NbO2 / NbO2 / Pt). x / Pt cells for crosspoint memory applications[J].IEEE Electron Device Letters,2012,33(2):236-238. The reported 1S1R devices have a limited number of stable cycles, and the fabrication process is relatively complex. Therefore, it is necessary to find a self-assembled NbO method that can achieve multiple stable cycles, is inexpensive, and has a simple fabrication method. x The method for 1S1R devices is necessary.

[0004] Currently, there are few reports on the transition between volatile and non-volatile resistive switching behavior of devices. For example, Bae et al. achieved the transition from volatile to non-volatile resistive switching by changing the applied electrical stress of Pt / NbOx / Pt devices from 2.5V to 3.5V (J. Bae, et al, Coexistence of bi-stable memory and mono-stable threshold resistance switching phenomena in amorphous NbO). x Films, APPL. PHYS. LETT., 2012, 100: 062902.). Hwang et al. demonstrated that applying a 2V positive electrical pulse to a Pt / NiO / Pt device can cause the device to switch from a bistable non-volatile resistive switching state to a monostable volatile resistive switching state; applying an electrical pulse in the opposite direction results in a reversible switching (I. Hwang, et al., Resistive switching transition induced by a voltage pulse in a Pt / NiO / Pt structure APPL. PHYS. LETT., 2010, 97, 052106). The aforementioned switching process of the device's resistive switching behavior may require higher electrical energy to the device, and the input from DC to a signal pulse is also relatively complex.

[0005] There are currently no reports on the regulation of the switching behavior of niobium oxide thin films by changing the limiting current. This invention studies the regulation of the switching behavior of niobium oxide thin films by limiting current, filling a gap in the prior art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for controlling the resistivity transition behavior of niobium oxide thin films by limiting current and its application in a three-dimensional stacked structure of a threshold selector switch or resistive switching memory.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for controlling the resistivity transition behavior of a niobium oxide thin film by limiting current specifically includes the following steps:

[0009] (1) NbO x Thin film preparation: NbO was deposited on a Pt / Ti / SiO2 / Si substrate using radio frequency magnetron sputtering with Nb2O5 as the target material. x film;

[0010] (2) Regulation of the thin film resistive switching behavior by limiting current: Apply a scanning voltage greater than the switching voltage; when the limiting current is controlled at 5mA, the NbOx thin film exhibits non-volatile resistive switching behavior; when the limiting current is controlled at 10mA, the NbOx thin film exhibits volatile resistive switching behavior; when the limiting current is controlled at 50mA, the NbOx thin film exhibits a combination of non-volatile and volatile resistive switching behavior.

[0011] Furthermore, the NbO x The thickness of the thin film is 75-125 nm, preferably 90-110 nm, and most preferably 100 nm;

[0012] Furthermore, in step (2), when applying a 5mA limiting current to the NbOx film during regulation, the applied scanning voltage sequence is 0→2V→0→-1.5V→0 or 2V→0→-1.5V→0→2V or -1.5V→0→2V→0→-1.5V. When applying a 10mA or 50mA limiting current to the NbOx film, the applied scanning voltage sequence is 0→(1.5-3)V→0→-(1.5-3)V→0 or (1.5-3)V→0→-(1.5-3)V→0→(1.5-3)V or -(1.5-3)V→0→(1.5-3)V→0→-(1.5-3)V.

[0013] Furthermore, in step (2), when applying a 10mA limiting current to the NbOx film, the applied scanning voltage sequence is 0→2V→0→-1.5V→0; ​​when applying a 50mA limiting current to the NbOx film, the applied scanning voltage sequence is 0→2V→0→-2V→0.

[0014] Furthermore, the NbO x The thin film is prepared as follows:

[0015] Radio frequency magnetron sputtering was used for deposition, with Nb2O5 ceramic target material placed on the target site in the magnetron sputtering reaction chamber. A Pt / Ti / SiO2 / Si substrate was used as the substrate, and part of the substrate was shielded to ensure that part of the lower electrode was not contaminated. The base vacuum was evacuated to 5*10 before sputtering began. -5 To prevent contamination of the substrate by impurities within the chamber, the Nb₂O₅ ceramic target was pre-sputtered for 60 seconds to remove surface contaminants. Then, reactive sputtering was performed under an argon atmosphere, with the sputtering pressure maintained at 0.2 Pa, the deposition temperature at 80 °C, and the sputtering power at 40 W. NbO₂ was obtained after 20 minutes of deposition. x film.

[0016] The above-mentioned adjustment of NbO disclosed in this invention x The limiting current of the thin film (I) cc At 5mA and 10mA, the device exhibits non-volatile resistive switching behavior and volatile resistive switching behavior, respectively; when I increases cc At 50mA, NbO x The non-volatile and volatile resistive behaviors occur simultaneously in NbO. x The device can exhibit 1S1R resistive switching behavior, and each resistive switching behavior of the device can be stably switched more than 100 times. The 1S1R resistive switching behavior of the present invention can suppress crosstalk current in the RRAM three-dimensional integrated structure during data reading. Therefore, the above-mentioned control method can be applied to threshold gating switches or resistive switching memories.

[0017] Compared with the prior art, the method of the present invention has the following advantages and beneficial effects:

[0018] The NbO obtained by the method of the present invention x The resistive switching behavior of the thin film exhibits different resistive switching behaviors, stabilizes after multiple cycles, and the method is simple and inexpensive. NbO x The resistive states of the thin films exhibiting different resistive switching behaviors are all relatively stable and can be stably cycled more than 100 times, with the required switching voltage being less than 1V. NbO x Thin film at 50mA I ccThe above-mentioned control method exhibits a phenomenon of coexistence of non-volatile and volatile resistive switching, namely 1S1R behavior, which can suppress crosstalk current in the three-dimensional integrated structure of RRAM during data reading. Therefore, the above-mentioned control method can be applied to threshold gating switches or resistive switching memories. Attached Figure Description

[0019] Figure 1 NbO prepared in Example 1 x The X-ray diffraction pattern of the thin film shows that the diffraction peak at 40° corresponds to the peak on the substrate. The image indicates the absence of NbO. x The appearance of the crystallization peak indicates that the prepared NbO x The thin film is amorphous;

[0020] Figure 2 NbO prepared in Example 1 x The scanning electron microscope (SEM) cross-sectional thickness image of the thin film shows that the preparation of NbO... x The film thickness is approximately 100 nm;

[0021] Figure 3 NbO prepared in Example 1 x X-ray photoelectron spectrum of the thin film (obtained after Ar+ etching to remove surface contaminants), based on Nb in the figure. 5+ and Nb 4+ The location where the valence binding energy appears indicates that NbO x The thin film is composed of NbO2 and Nb2O5, and the ratio of the two components can be determined to be 1:1 based on the peak areas of the two components.

[0022] Figure 4 When the current limit is 5mA in Example 1, NbO x (a) IV cycle curve, (b) tolerance, (c) hold-time plot of the thin film; From the figures, it can be seen that when the limiting current is 5mA, the device exhibits non-volatile resistive switching behavior, and the SET voltage (V) set The RESET voltage is approximately 0.6V. reset It has a voltage rating of approximately -0.45V, a cycle tolerance of up to 100 cycles, an on / off ratio of approximately 200, and can be stably maintained in both high and low resistance states for 7000 seconds.

[0023] Figure 5 When the current limit is 10mA in Example 1, NbO x (a) I-V cycle curves, (b) tolerance, and (c) cumulative probability distributions of threshold voltage and holding voltage for the thin film. The figures show that when the limiting current is 10 mA, the device exhibits volatile resistive switching behavior, with an on / off ratio of approximately 10. Both HRS and LRS can be stably cycled for over 130 cycles. The threshold voltage (|V) thConcentrate 0.67~0.68V, maintain voltage (│V) h │) Concentrated at 0.60~0.61V.

[0024] Figure 6 When the current limit is 50mA in Example 1, NbO x Figure (a) shows the IV curves of the 1S1R behavior of the thin film, and (b) shows the IV curves at the 1st, 50th, and 100th times. In Figure (a), the shaded area represents the non-volatile resistive switching behavior, and the areas on both sides of the shaded area represent the volatile threshold resistive switching behavior. It can be seen that the device exhibits 1S1R resistive switching behavior at 50mA. From Figure (b), it can be seen that NbO... x The thin film exhibited stable 1S1R resistive switching behavior at the 1st, 50th, and 100th times. Detailed Implementation

[0025] The technical solution of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0026] The Pt / Ti / SiO2 / Si substrates used in the following examples are Pt(111) / Ti / SiO2 / Si substrates purchased from Hefei Yuanjing Technology Materials Co., Ltd., with film thicknesses of Pt(111): 150nm; Ti: 20nm; SiO2: 300nm.

[0027] The Nb2O5 ceramic target material used was purchased from Beijing Gaodewei Metal Technology Development Co., Ltd., with a purity of 99.99% and dimensions of 50.8 mm in diameter and 3 mm in thickness.

[0028] Example 1: Regulation of the resistivity transition behavior of niobium oxide thin films by limiting current

[0029] (1) NbO x Thin film preparation: NbO was deposited on the substrate using radio frequency magnetron sputtering. x The thin film was produced using an Nb₂O₅ ceramic target, placed on the target site within the magnetron sputtering reaction chamber. A Pt / Ti / SiO₂ / Si substrate was used as the substrate, with a portion of the substrate shielded to ensure that part of the lower electrode remained uncontaminated. Before sputtering began, the base vacuum was evacuated to 5*10⁻⁶. -5 To prevent impurities in the chamber from contaminating the substrate, the Nb₂O₅ ceramic target was pre-sputtered for 60 seconds to remove surface contaminants. Then, reactive sputtering was performed under an argon atmosphere, with the sputtering pressure maintained at 0.2 Pa, the deposition temperature at 80 °C, and the sputtering power at 40 W. NbO₂ was obtained after 20 minutes of deposition. x film.

[0030] (2) NbO xTesting of thin film structure and composition: NbO prepared in step (1) x The thin film was subjected to X-ray diffraction analysis, and the results are as follows: Figure 1 As shown, the diffraction peak at 40° corresponds to the substrate peak, and there is no NbO. x The appearance of the crystallization peak indicates that the NbO prepared in this experiment... x The thin film is amorphous. The cross-sectional thickness of the thin film was measured, and the results are as follows: Figure 2 As shown, the NbO prepared in this experiment x The film thickness is approximately 100 nm. XPS composition analysis of the film yielded the following results: Figure 3 As shown, NbO x The components are NbO2 and Nb2O5, and the ratio of the two components is approximately 1:1.

[0031] (3) Testing of electrical properties: The NbO deposited by the above method was tested. x The electrical properties of the thin film were tested using a 4200-SCS semiconductor parameter tester. During the test, one end of the probe in the instrument was in contact with the lower electrode, and the other end was in contact with the surface of the thin film to be tested. First, a limiting current of 5mA was applied to the thin film, and the scanning voltage sequence was 0→2V→0→-1.5V→0. Then, a limiting current of 10mA was applied to the thin film, and the scanning voltage sequence was 0→2V→0→-1.5V→0. Finally, a limiting current of 50mA was applied to the thin film, and the scanning voltage sequence was 0→2V→0→-2V→0.

[0032] Experimental results showed that NbO x The on / off ratio of the non-volatile resistive switching behavior of the thin film is approximately 200, V. set Approximately 0.6V, V reset The voltage is approximately -0.45V. Both the high-resistivity (HRS) and low-resistivity (LRS) states can be stably maintained for over 7000 seconds, and both HRS and LRS can be stably cycled over 100 times. (NbO) x The on / off ratio of the thin film's volatile resistivity behavior is approximately 10. Both HRS and LRS can be stably cycled for over 130 times without any fluctuations. th |Concentrated 0.67~0.68V, |V h | Concentrated 0.60~0.61V.

[0033] Regulation of membrane switch behavior by limiting current: When the limiting current is 5mA, such as Figure 4 (a) The direction of the response current is 1→2→3→4, and the thin film exhibits non-volatile resistive switching behavior. When the limiting current is 10mA, as... Figure 5 (a) The direction of the response current is 1→2→3→4, and the thin film exhibits volatile resistive switching behavior. When the limiting current is 50mA, as... Figure 6 (a) The direction of the response current is 1→2→3→4, and the thin film exhibits resistive switching behavior that combines non-volatile and volatile characteristics.

[0034] The electrical property testing of this invention employs a voltage scanning method to obtain the response current. In practical applications, the voltage scanning method can vary. For example, when limiting the current to 5mA and 10mA, the method can be 0→2V→0→-1.5V→0, or 2V→0→-1.5V→0→2V or -1.5V→0→2V→0→-1.5V. When limiting the current to 50mA, the method is 0→2V→0→-2V→0, or 2V→0→-2V→0→2V or -2V→0→2V→0→-2V. Different electrical property testing instruments will yield the same results. In all three cases, scanning the voltage up to 1V will produce the same result, meaning that a resistive change can be achieved when the scanning voltage is greater than the switching voltage.

[0035] In the experiment, for the volatile resistive switching behavior and the 1S1R resistive switching behavior, the positive and negative scanning voltages were further increased. The test results showed that the same resistive switching behavior was still exhibited when the scanning voltage was increased to +3V or -3V. For the non-volatile resistive switching behavior, when the negative scanning voltage was applied to -3V, it may cause the device to break down and burn out in reverse. Therefore, this was not attempted in the experiment.

Claims

1. A method for controlling the resistivity transition behavior of a niobium oxide thin film by limiting current, specifically comprising the following steps: (1) Preparation of NbOx thin film: NbOx thin film was deposited on Pt / Ti / SiO2 / Si substrate using radio frequency magnetron sputtering with Nb2O5 as target material; the NbO... x The thin film is prepared as follows: Radio frequency magnetron sputtering was used for deposition, with Nb2O5 ceramic target material placed on the target site in the magnetron sputtering reaction chamber. A Pt / Ti / SiO2 / Si substrate was used as the substrate, and part of the substrate was shaded to ensure that part of the lower electrode was not contaminated. The base vacuum was evacuated to 5 × 10⁻⁶ before sputtering began. −5 Following this, the Nb₂O₅ ceramic target was pre-sputtered for 60 s, and then reactive sputtering was performed under an argon atmosphere. The sputtering pressure was maintained at 0.2 Pa, the deposition temperature was 80 °C, the sputtering power was 40 W, and NbO was obtained after 20 minutes of deposition. x film; (2) Regulation of thin film resistive switching behavior by limiting current: When a scanning voltage greater than the switching voltage is applied, the NbOx thin film exhibits non-volatile resistive switching behavior when the limiting current is controlled at 5 mA. When the control current limit is 10 mA, the NbOx thin film exhibits volatile resistive switching behavior; When the control current limit is 50 mA, the NbOx thin film exhibits resistive switching behavior that combines non-volatile and volatile characteristics. The NbO x The thickness of the thin film is 75-125 nm; In step (2), when applying a 5 mA limiting current to the NbOx film, the applied scanning voltage sequence is 0→2V→0→-1.5V→0 or 2V→0→-1.5V→0→2V or -1.5V→0→2V→0→-1.5V. When applying a 10 mA or 50 mA limiting current to the NbOx film, the applied scanning voltage sequence is 0→1.5V→0→−1.5V→0 or 1.5V→0→-1.5V→0→1.5V or -1.5V→0→1.5V→0→-1.5V.

2. The application of the control method according to claim 1 in a threshold gating switch or resistive switching memory.

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