A method for preparing electrode materials in ReRAM memory

Abstract

This invention relates to the field of electrode material technology, specifically to a method for preparing electrode materials for ReRAM memory. The method uses a dual-ligand copper precursor as the sole metal source and employs a hot-wall metal-organic chemical vapor deposition (MOCVD) apparatus. The method induces the stepwise thermal decomposition of acetylacetone and hexafluoroacetylacetone ligands in the precursor through a substrate temperature gradient. The in-situ escape of the ligand decomposition products forms nanopores. Combined with a mild annealing treatment after deposition, the electrode structure is gradient-controlled. Unreacted precursors are recovered by condensing the exhaust gas, achieving raw material recycling and yielding a gradient porous ReRAM electrode material. This invention solves the industry problems of random conductive filaments, high forming voltage, and template dependence in traditional electrode preparation through stepwise ligand pyrolysis and in-situ self-generated pores induced by temperature gradients. It provides a novel solution for the efficient template-free preparation of high-performance ReRAM electrode materials.

Description

Technical Field

[0001] This invention relates to the field of electrode material technology, and specifically to a method for preparing electrode materials for ReRAM memory. Background Technology

[0002] In the field of resistive switching memory (RSM), noble metal electrodes suffer from inherent defects such as fixed interface barriers and random filament growth positions. These defects lead to high operating voltages, short cycle lives, and poor device consistency, becoming key bottlenecks restricting the industrial application of RSMs. Traditional electrode materials rely on single-component inert metals and conventional active metals. This static physical sputtering-based electrode fabrication method has inherent flaws: the interface barrier of inert metal electrodes is untunable, resulting in random filament nucleation sites and drastic fluctuations in switching parameters; while conventional active metal electrodes can participate in filament formation, they lack the ability to actively confine the filament diameter and morphology, leading to over-implantation that results in thick filaments and random dissolution, causing device cycle lives to fall below 10. 6 Furthermore, the standard deviation of the high-resistivity / low-resistivity distribution exceeds 0.5, which severely restricts the practical application of resistive random access memory in high-density storage and neuromorphic computing.

[0003] In recent years, researchers have attempted to improve device performance by introducing nanopore templates and interface modification layers to control the growth path of conductive filaments. However, such methods not only require additional template preparation and removal steps, resulting in lengthy processes, but also leave template residues that contaminate the electrode / resistive switching layer interface, leading to decreased device yield and reliability degradation. Furthermore, the pore size of the external template is limited by the template preparation process, making it difficult to effectively confine sub-5 nm conductive filaments. Therefore, how to construct a template-free, in-situ self-pore-forming gradient structure electrode material with adjustable pore size, simultaneously achieving interface matching optimization and active confinement of conductive filaments in a single deposition process, has become a core technical challenge that urgently needs to be overcome in the field of resistive switching memory electrode materials.

[0004] To address the above problems, the present invention provides a solution. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing electrode materials in ReRAM memory, which has the advantages of template-free in-situ self-generated pores, programmable control of gradient structure, low operating voltage, long cycle life and recyclable raw materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing electrode materials in ReRAM memory uses a dual-ligand copper precursor as the sole metal source and employs a hot-wall metal-organic chemical vapor deposition (MOCVD) device. The substrate temperature gradient induces the stepwise thermal decomposition of acetylacetone ligands and hexafluoroacetylacetone ligands in the precursor. The in-situ escape of the ligand decomposition products forms nanopores. The gradient control of the electrode structure is achieved by combining the mild annealing treatment after deposition. The unreacted precursor is recovered by condensing the tail gas to achieve the recycling of raw materials, thereby obtaining a ReRAM electrode material with a gradient porous structure.

[0007] Furthermore, a method for preparing electrode materials in a ReRAM memory includes the following steps:

[0008] S1: Take a silicon / silicon dioxide substrate that has been cleaned with standard RCA. A titanium nitride bottom electrode layer with a thickness of 50nm has been pre-deposited on the substrate surface. Place the substrate in an oxygen plasma treatment chamber, set the radio frequency power to 80W, the oxygen flow rate to 50sccm, and treat with oxygen plasma for 60s to obtain a surface-activated substrate.

[0009] S2: Transfer the surface-activated substrate to the hot-wall metal-organic chemical vapor deposition reaction chamber. The substrate is placed on a graphite substrate with a temperature gradient distribution. The substrate uses independent heating control in zones, with the low-temperature zone set at 200℃ and the high-temperature zone at 350℃. The substrate rotation speed is set to 30 rpm. Evacuate the reaction chamber to a base vacuum of 1×10⁻⁶. -3 Pa, then high-purity nitrogen gas was introduced as a carrier gas, the reaction pressure was adjusted to 100 Pa, and the reaction chamber was purged with a nitrogen gas flow of 50 sccm for 15 min to obtain a temperature-stable substrate.

[0010] S3: The dual-ligand copper precursor is loaded into a stainless steel bubbler. After filling in an inert atmosphere glove box, it is sealed and transferred to a metal-organic chemical vapor deposition equipment. The bubbler temperature is set to 85℃. High-purity nitrogen is used as the carrier gas. The carrier gas flow rate is precisely controlled to be 20-50 sccm using a mass flow controller. The precursor vapor is then transported to the reaction chamber through a 100℃ heating pipeline to obtain the precursor vapor transport flow.

[0011] S4: After the reaction chamber pressure, substrate temperature, and bubbler temperature stabilize, open the precursor delivery valve to begin metal-organic chemical vapor deposition. During deposition, maintain the substrate pedestal rotation speed at 10-50 rpm and the reaction pressure at 50-200 Pa. Use a mass flow controller to control two streams of nitrogen. The first stream of nitrogen carries the precursor vapor into the reaction chamber via the bubbler at a flow rate of 20-50 sccm. The second stream of nitrogen acts as a dilution gas and enters the reaction chamber directly via a bypass pipe at a flow rate of 40-100 sccm. The two streams of nitrogen are mixed by a gas mixing device before entering the reaction chamber. The deposition time is 60-120 min. During deposition, use a quartz crystal micro-sky plain to monitor the deposition rate and use a residual gas analyzer to monitor the partial pressure changes of the decomposition products to obtain the deposited gradient electrode.

[0012] S5: After deposition, close the precursor delivery valve, maintain the substrate temperature, control the nitrogen flow rate to 50-100 sccm through the mass flow controller, and directly enter the reaction chamber through the bypass pipe. Purge the reaction chamber for 15-60 min, and then condense and collect the unreacted precursor through a -40℃ to -20℃ cold trap. The condensed and collected precursor can be used for subsequent batches after drying. Then turn off the substrate heating and cool to room temperature at a rate of 2-10℃ / min. During the cooling process, keep the nitrogen purging to obtain the cooled gradient electrode.

[0013] S6: After cooling, the gradient electrode is removed from the reaction chamber and transferred to a rapid thermal annealing furnace. Post-treatment annealing is carried out under a nitrogen atmosphere. The annealing temperature is set to 350-450℃, the heating rate is 30-50℃ / s, and the holding time is 150-300s. Then, it is naturally cooled to room temperature to obtain the electrode material.

[0014] Furthermore, the preparation method of the dual-ligand copper precursor includes the following steps:

[0015] A1: In a nitrogen-protected glove box, weigh cuprous oxide and add it to a flask, then add degassed toluene. Stir magnetically at 300 rpm for 15-20 min to obtain a copper source suspension. In a fume hood, measure acetylacetone and hexafluoroacetylacetone separately. Slowly add acetylacetone dropwise to the copper source suspension at a rate of 0.5 ml / min, maintaining a stirring speed of 300 rpm during the dropwise addition. After the dropwise addition is complete, continue stirring for 15-20 min. Then, slowly add hexafluoroacetylacetone dropwise to the flask at a rate of 0.5 ml / min, maintaining a stirring speed of 300 rpm during the dropwise addition. The reaction solution gradually changes from brick red to blue, yielding a reaction mixture.

[0016] A2: Place the reaction mixture at room temperature, set the stirring speed to 400-600 rpm, and stir for 2 hours. During the stirring process, use a condenser to seal and prevent air from entering and solvent from evaporating. After stirring, heat in an oil bath at a rate of 2℃ / min until the temperature reaches 50℃. After reaching 50℃, maintain the temperature for 1 hour. During the constant temperature reaction, keep the stirring speed constant and use a condenser for reflux to prevent solvent from evaporating. After the reaction is complete, allow it to cool naturally to room temperature to obtain a blue transparent solution.

[0017] A3: Use a Buchner funnel to filter the blue transparent solution. The funnel is pre-lined with double layers of qualitative filter paper and 1 cm thick diatomaceous earth. The vacuum degree of filtration is set to -0.08 MPa. Collect the filtrate, discard the unreacted solid residue, and collect the filtrate in a round-bottom flask. Use a rotary evaporator to concentrate the solution under reduced pressure in a 40°C water bath. The vacuum degree of the rotary evaporator is set to -0.09 MPa, and the rotation speed is set to 80 rpm. Concentrate to 25% of the initial volume to obtain the concentrated solution.

[0018] A4: Transfer the concentrate to an Erlenmeyer flask, set the magnetic stirrer speed to 200 rpm, and add n-hexane to the concentrate at a rate of 1 drop / s. A light blue precipitate will appear during the addition. After the addition is complete, keep the speed constant and continue stirring for 15 min. After stirring, seal the Erlenmeyer flask and place it in a -20℃ refrigerator for 12 h. After standing, take it out and use a Buchner funnel to collect the crystals by vacuum filtration. Set the filtration vacuum degree to -0.08 MPa. After filtration, wash the crystals three times with n-hexane pre-cooled at -20℃ to obtain the crude product.

[0019] A5: Transfer the crude product to a round-bottom flask, add dichloromethane, wherein the mass-to-volume ratio of crude product to dichloromethane is 1g:3ml, stir at 200-300rpm at room temperature until the crude product is completely dissolved, then slowly add n-hexane dropwise under magnetic stirring while maintaining a constant stirring speed, with a dropping rate of 1ml / min. After the addition is complete, continue stirring for 15min, seal the round-bottom flask and place it in a -20℃ refrigerator for recrystallization for 12h. After recrystallization, remove the flask and collect the crystals by vacuum filtration using a Buchner funnel, with the filtration vacuum set to -0.08MPa. After filtration, wash the crystals twice with n-hexane pre-cooled at -20℃ to obtain the purified product.

[0020] A6: Transfer the purified product to a vacuum drying oven, set the drying temperature to 25℃ and the vacuum degree to -0.09MPa, and dry for 6 hours. After drying, take it out and transfer it to a glass sample vial under nitrogen protection. Seal and store it in a glove box to obtain the dual-ligand copper precursor.

[0021] Furthermore, in step A1, the mass ratio of cuprous oxide to degassed toluene is 1:14, and the molar ratio of cuprous oxide, acetylacetone, and hexafluoroacetylacetone is 1:1:1; in step A4, the volume ratio of the concentrate to n-hexane is 1:3.3; and in step A5, the volume ratio of dichloromethane to n-hexane is 1:4.

[0022] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0023] 1: This invention creates a novel gradient electrode fabrication mode that utilizes a three-level synergistic approach of ligand-level pyrolysis, temperature gradient induction, and in-situ self-generated pores. It achieves stepwise decomposition by leveraging the difference in thermal stability between acetylacetone ligand and hexafluoroacetylacetone ligand in a dual-ligand copper precursor. The spatial distribution of decomposition products is induced by the substrate temperature gradient, and the in-situ escape of ligand decomposition gases forms a gradient porous structure. This systematically solves the key problems of fixed interface barriers, random growth of conductive filaments, and high forming voltage in traditional ReRAM electrodes.

[0024] 2: This invention uses a self-synthesized dual-ligand copper precursor as the core to construct a gradient electrode preparation system for one-step MOCVD deposition. By designing the precursor molecules to embed the pore-forming function, using temperature gradients to achieve continuous changes in porosity along the electrode thickness direction, and automatically escaping ligand decomposition products to avoid template residue, it realizes a three-in-one integrated manufacturing process of electrode deposition, pore-forming and gradient control. It shows excellent adaptability, especially for ReRAM electrode systems that require precise confinement of conductive filaments.

[0025] 3: This invention integrates a hot-wall MOCVD device with a self-synthesized dual-ligand copper precursor, compressing the traditional electrode fabrication process that requires template assistance, multi-step deposition, and post-processing pore-forming into a one-step continuous green manufacturing process with a single device, a single precursor, and no template. It achieves programmable control of gradient porous structure, electrode thickness, and porosity during the whole vapor deposition process, providing a brand-new solution for the low-cost, high-consistency, and easily scaled-up fabrication of high-performance ReRAM electrode materials. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0028] Example 1

[0029] 1. In a nitrogen-protected glove box, weigh 7.16g of cuprous oxide and add it to a flask. Then add 100.24g of degassed toluene and stir magnetically at 300rpm for 15min to obtain a copper source suspension. In a fume hood, measure 5.05g of acetylacetone and 10.29g of hexafluoroacetylacetone. Slowly add acetylacetone dropwise to the copper source suspension at a rate of 0.5ml / min, while maintaining a stirring speed of 300rpm during the dropwise addition. After the dropwise addition is complete, continue stirring for 15-20min. Then slowly add hexafluoroacetylacetone dropwise to the flask at a rate of 0.5ml / min, while maintaining a stirring speed of 300rpm during the dropwise addition. The reaction solution gradually changes from brick red to blue, yielding 120.5g of reaction mixture.

[0030] 2: Place 120.5g of the reaction mixture at room temperature, set the stirring speed to 400rpm, and stir for 2 hours. During the stirring process, use a condenser to seal the mixture to prevent air from entering and solvent from evaporating. After stirring, heat the mixture in an oil bath at a rate of 2℃ / min until it reaches 50℃. After reaching 50℃, maintain the temperature for 1 hour. During the constant temperature reaction, keep the stirring speed constant and use a condenser for reflux to prevent solvent from evaporating. After the reaction is complete, allow it to cool naturally to room temperature to obtain 118g of blue transparent solution.

[0031] 3: Use a Buchner funnel to filter the blue transparent solution. The funnel is pre-lined with double layers of qualitative filter paper and 1 cm thick diatomaceous earth. The vacuum degree of filtration is set to -0.08 MPa. Collect the filtrate, discard the unreacted solid residue, and collect the filtrate in a round-bottom flask. Use a rotary evaporator to concentrate the solution under reduced pressure in a 40℃ water bath. The vacuum degree of the rotary evaporator is set to -0.09 MPa, and the rotation speed is set to 80 rpm. Concentrate to 25% of the initial volume to obtain 28 ml of concentrate, which is 27.5 g of concentrate.

[0032] 4. Transfer 27.5g of the concentrate to an Erlenmeyer flask. Set the magnetic stirrer speed to 200rpm and add 92.4ml of n-hexane to the concentrate at a rate of 1 drop / s, where the volume ratio of concentrate to n-hexane is 1:3.3. A light blue precipitate appears during the dropwise addition. After the addition is complete, keep the speed constant and continue stirring for 15min. After stirring, seal the Erlenmeyer flask and place it in a -20℃ refrigerator for 12h. After standing, remove it and collect the crystals by vacuum filtration using a Buchner funnel. Set the vacuum degree of filtration to -0.08MPa. After filtration, wash the crystals three times with n-hexane pre-cooled at -20℃ to obtain 12.2g of crude product.

[0033] 5: Transfer 12.2g of crude product to a round-bottom flask, add 36.6ml of dichloromethane, and stir at 200rpm at room temperature until the crude product is completely dissolved. Then, while maintaining the same speed, slowly add 146.4ml of n-hexane dropwise with magnetic stirring at a rate of 1ml / min. After the addition is complete, continue stirring for 15min. Seal the round-bottom flask and place it in a -20℃ refrigerator for recrystallization for 12h. After recrystallization, remove the flask and collect the crystals by vacuum filtration using a Buchner funnel with a vacuum degree of -0.08MPa. After filtration, wash the crystals twice with pre-cooled n-hexane at -20℃ to obtain 9.6g of purified product.

[0034] 6: Transfer 9.6g of purified product to a vacuum drying oven, set the drying temperature to 25℃ and the vacuum degree to -0.09MPa, and dry for 6h. After drying, take it out and transfer it to a glass sample bottle under nitrogen protection. Seal and store it in a glove box to obtain 9.4g of the dual-ligand copper precursor prepared in Example 1.

[0035] Example 2

[0036] 1. In a nitrogen-protected glove box, weigh 14.32 g of cuprous oxide and add it to a flask. Then add 200.48 g of degassed toluene and stir magnetically at 300 rpm for 20 min to obtain a copper source suspension. In a fume hood, measure 10.1 g of acetylacetone and 20.58 g of hexafluoroacetylacetone. Slowly add acetylacetone dropwise to the copper source suspension at a rate of 0.5 ml / min, while maintaining a stirring speed of 300 rpm during the dropwise addition. After the dropwise addition is complete, continue stirring for 20 min. Then slowly add hexafluoroacetylacetone dropwise to the flask at a rate of 0.5 ml / min, while maintaining a stirring speed of 300 rpm during the dropwise addition. The reaction solution gradually changes from brick red to blue, yielding 241 g of reaction mixture.

[0037] 2: Place 241g of the reaction mixture at room temperature, set the stirring speed to 600rpm, and stir for 2 hours. During the stirring process, use a condenser to seal the mixture to prevent air from entering and solvent from evaporating. After stirring, heat the mixture in an oil bath at a rate of 2℃ / min until it reaches 50℃. After reaching 50℃, maintain the temperature for 1 hour. During the constant temperature reaction, keep the stirring speed constant and use a condenser for reflux to prevent solvent from evaporating. After the reaction is complete, allow it to cool naturally to room temperature to obtain 236g of blue transparent solution.

[0038] 3: Use a Buchner funnel to filter the blue transparent solution. The funnel is pre-lined with double layers of qualitative filter paper and 1 cm thick diatomaceous earth. The vacuum degree of filtration is set to -0.08 MPa. Collect the filtrate, discard the unreacted solid residue, and collect the filtrate in a round-bottom flask. Use a rotary evaporator to concentrate the solution under reduced pressure in a 40℃ water bath. The vacuum degree of the rotary evaporator is set to -0.09 MPa, and the rotation speed is set to 80 rpm. Concentrate to 25% of the initial volume to obtain 56 ml of concentrate, which is 55 g of concentrate.

[0039] 4: Transfer 56 ml of concentrate to an Erlenmeyer flask. Set the magnetic stirrer speed to 200 rpm and add 184.8 ml of n-hexane to the concentrate at a rate of 1 drop / s. A light blue precipitate appears during the addition. After the addition is complete, keep the speed constant and continue stirring for 15 min. After stirring, seal the Erlenmeyer flask and place it in a -20℃ refrigerator for 12 h. After standing, remove it and collect the crystals by vacuum filtration using a Buchner funnel. Set the vacuum degree of filtration to -0.08 MPa. After filtration, wash the crystals three times with n-hexane pre-cooled at -20℃ to obtain 24.5 g of crude product.

[0040] 5: Transfer 24.5g of crude product to a round-bottom flask, add 73.5ml of dichloromethane, and stir at 300rpm at room temperature until the crude product is completely dissolved. Then, while maintaining the same speed, slowly add 294ml of n-hexane with magnetic stirring at a rate of 1ml / min. After the addition is complete, continue stirring for 15min. Seal the round-bottom flask and place it in a -20℃ refrigerator for recrystallization for 12h. After recrystallization, remove the flask and collect the crystals by vacuum filtration using a Buchner funnel with a vacuum degree of -0.08MPa. After filtration, wash the crystals twice with pre-cooled n-hexane at -20℃ to obtain 19.3g of purified product.

[0041] 6: Transfer 19.3g of purified product to a vacuum drying oven, set the drying temperature to 25℃ and the vacuum degree to -0.09MPa, and dry for 6h. After drying, take it out and transfer it to a glass sample bottle under nitrogen protection. Seal and store it in a glove box to obtain 18.9g of the dual-ligand copper precursor prepared in Example 2.

[0042] Example 3

[0043] 1: Take a silicon / silicon dioxide substrate that has been cleaned with standard RCA. A titanium nitride bottom electrode layer with a thickness of 50nm has been pre-deposited on the substrate surface. Place the substrate in an oxygen plasma treatment chamber, set the radio frequency power to 80W, the oxygen flow rate to 50sccm, and treat with oxygen plasma for 60s to obtain a surface-activated substrate.

[0044] 2. The surface-activated substrate is transferred to a hot-wall metal-organic chemical vapor deposition reaction chamber. The substrate is placed on a graphite substrate with a temperature gradient distribution. The substrate is heated independently in zones, with the low-temperature zone set at 200℃ and the high-temperature zone at 350℃. The substrate rotation speed is set to 30 rpm. The chamber is evacuated to a base vacuum of 1×10⁻⁶. -3 Pa, then high-purity nitrogen gas was introduced as a carrier gas, the reaction pressure was adjusted to 100 Pa, and the reaction chamber was purged with a nitrogen gas flow of 50 sccm for 15 min to obtain a temperature-stable substrate.

[0045] 3: The dual-ligand copper precursor prepared in Example 1 was loaded into a stainless steel bubbler. After filling in an inert atmosphere glove box, it was sealed and transferred to a metal-organic chemical vapor deposition equipment. The bubbler temperature was set to 85°C. High-purity nitrogen was used as the carrier gas. The carrier gas flow rate was precisely controlled to 20 sccm using a mass flow controller. The precursor vapor was transported to the reaction chamber through a 100°C heating pipeline to obtain the precursor vapor transport flow.

[0046] 4. After the reaction chamber pressure, substrate temperature, and bubbler temperature stabilize, open the precursor delivery valve to begin metal-organic chemical vapor deposition. During deposition, maintain the substrate pedestal rotation speed at 10 rpm and the reaction pressure at 50 Pa. Use a mass flow controller to control two streams of nitrogen. The first stream of nitrogen carries the precursor vapor into the reaction chamber via the bubbler at a flow rate of 20 sccm. The second stream of nitrogen acts as a dilution gas and enters the reaction chamber directly via a bypass pipe at a flow rate of 40 sccm. The two streams of nitrogen are mixed by a gas mixing device before entering the reaction chamber. The deposition time is 120 min. During deposition, a quartz crystal micro-sky flat surface is used to monitor the deposition rate, and a residual gas analyzer is used to monitor the partial pressure changes of the decomposition products to obtain the deposited gradient electrode.

[0047] 5: After deposition, close the precursor delivery valve, maintain the substrate temperature, control the nitrogen flow rate to 50 sccm through the mass flow controller, and directly enter the reaction chamber through the bypass pipe. Purge the reaction chamber for 60 min, and then condense and collect the unreacted precursor through a cold trap at -40℃ to -20℃. The condensed and collected precursor can be used for subsequent batches after drying. Then, turn off the substrate heating and cool to room temperature at a rate of 2℃ / min. During the cooling process, keep the nitrogen purging to obtain the cooled gradient electrode.

[0048] 6: After cooling, the gradient electrode is removed from the reaction chamber and transferred to a rapid thermal annealing furnace. Post-treatment annealing is performed under a nitrogen atmosphere. The annealing temperature is set to 350°C, the heating rate is 30°C / s, and the holding time is 150s. Then, it is naturally cooled to room temperature to obtain the electrode material prepared in Example 3.

[0049] Example 4

[0050] 1: Take a silicon / silicon dioxide substrate that has been cleaned with standard RCA. A titanium nitride bottom electrode layer with a thickness of 50nm has been pre-deposited on the substrate surface. Place the substrate in an oxygen plasma treatment chamber, set the radio frequency power to 80W, the oxygen flow rate to 50sccm, and treat with oxygen plasma for 60s to obtain a surface-activated substrate.

[0051] 2. The surface-activated substrate is transferred to a hot-wall metal-organic chemical vapor deposition reaction chamber. The substrate is placed on a graphite substrate with a temperature gradient distribution. The substrate is heated independently in zones, with the low-temperature zone set at 200℃ and the high-temperature zone at 350℃. The substrate rotation speed is set to 30 rpm. The chamber is evacuated to a base vacuum of 1×10⁻⁶. -3 Pa, then high-purity nitrogen gas was introduced as a carrier gas, the reaction pressure was adjusted to 100 Pa, and the reaction chamber was purged with a nitrogen gas flow of 50 sccm for 15 min to obtain a temperature-stable substrate.

[0052] 3: The dual-ligand copper precursor is loaded into a stainless steel bubbler. After filling in an inert atmosphere glove box, it is sealed and transferred to a metal-organic chemical vapor deposition equipment. The bubbler temperature is set to 85℃, and high-purity nitrogen is used as the carrier gas. The carrier gas flow rate is precisely controlled to 50 sccm using a mass flow controller, so that the precursor vapor is delivered to the reaction chamber through a 100℃ heating pipeline to obtain the precursor vapor transport flow.

[0053] 4. After the reaction chamber pressure, substrate temperature, and bubbler temperature stabilize, open the precursor delivery valve to begin metal-organic chemical vapor deposition. During deposition, maintain the substrate pedestal rotation speed at 50 rpm and the reaction pressure at 200 Pa. Use a mass flow controller to control two streams of nitrogen gas. The first stream of nitrogen gas carries the precursor vapor into the reaction chamber via the bubbler at a flow rate of 50 sccm. The second stream of nitrogen gas, used as a dilution gas, enters the reaction chamber directly via a bypass pipe at a flow rate of 100 sccm. The two streams of nitrogen gas are mixed by a gas mixing device before entering the reaction chamber. The deposition time is 60 min. During deposition, a quartz crystal micro-sky plain is used to monitor the deposition rate on-site, and a residual gas analyzer is used to monitor the partial pressure changes of the decomposition products to obtain the deposited gradient electrode.

[0054] 5: After deposition, close the precursor delivery valve, maintain the substrate temperature, control the nitrogen flow rate to 100 sccm through the mass flow controller, and directly enter the reaction chamber through the bypass pipe. Purge the reaction chamber for 15 min, and then condense and collect the unreacted precursor through a cold trap at -40℃ to -20℃. The condensed and collected precursor can be used for subsequent batches after drying. Then, turn off the substrate heating and cool to room temperature at a rate of 10℃ / min. During the cooling process, keep the nitrogen purging to obtain the cooled gradient electrode.

[0055] 6: After cooling, the gradient electrode is removed from the reaction chamber and transferred to a rapid thermal annealing furnace. Post-treatment annealing is performed under a nitrogen atmosphere. The annealing temperature is set to 450℃, the heating rate is 50℃ / s, and the holding time is 150-300s. Then, it is naturally cooled to room temperature to obtain the electrode material prepared in Example 4.

[0056] Comparative Example 1

[0057] In this comparative example, commercially available copper hexafluoroacetylacetonate (grade: 479407, Sigma-Aldrich, purity 98%, sublimation temperature 60-70℃) was used instead of the dual-ligand copper precursor prepared in Example 1. Other components were the same as in Example 3, and the process parameters were adjusted according to the sublimation characteristics of the commercially available precursor. The specific steps are as follows:

[0058] 1: Take a silicon / silicon dioxide substrate that has been cleaned with standard RCA. A titanium nitride bottom electrode layer with a thickness of 50nm has been pre-deposited on the substrate surface. Place the substrate in an oxygen plasma treatment chamber, set the radio frequency power to 80W, the oxygen flow rate to 50sccm, and treat with oxygen plasma for 60s to obtain a surface-activated substrate.

[0059] 2. The surface-activated substrate is transferred to a hot-wall metal-organic chemical vapor deposition reaction chamber. The substrate is placed on a graphite substrate with a temperature gradient distribution. The substrate uses independent heating control in zones, with the low-temperature zone set at 200℃ and the high-temperature zone at 350℃. The substrate rotation speed is set to 30 rpm. The reaction chamber is then evacuated until the vacuum level reaches 1×10⁻⁶. -3 When the pressure reaches 100 Pa, the pumping is stopped, and then high-purity nitrogen is introduced as a carrier gas. The reaction pressure is adjusted to 100 Pa, and the reaction chamber is purged with a nitrogen flow of 50 sccm for 15 min to obtain a temperature-stable substrate.

[0060] 3: Weigh 10g of commercially available copper hexafluoroacetylacetonate and put it into a stainless steel bubbler. After filling in an inert atmosphere glove box, seal and transfer it to a metal-organic chemical vapor deposition equipment. Set the bubbler temperature to 65℃, use high-purity nitrogen as the carrier gas, and use a mass flow controller to precisely control the carrier gas flow rate to 20sccm. The precursor vapor is then transported to the reaction chamber through a 100℃ heating pipeline to obtain the precursor vapor transport flow.

[0061] 4. After the reaction chamber pressure, substrate temperature, and bubbler temperature stabilize, open the precursor delivery valve to begin metal-organic chemical vapor deposition. During deposition, maintain the substrate pedestal rotation speed at 10 rpm and the reaction pressure at 50 Pa. Use a mass flow controller to control two streams of nitrogen. The first stream of nitrogen carries the precursor vapor into the reaction chamber via the bubbler at a flow rate of 20 sccm. The second stream of nitrogen, as a dilution gas, enters the reaction chamber directly via a bypass pipe at a flow rate of 40 sccm. The two streams of nitrogen are mixed by a gas mixing device before entering the reaction chamber. The deposition time is 120 min. During deposition, a quartz crystal micro-sky flat surface is used to monitor the deposition rate, and a residual gas analyzer is used to monitor the partial pressure changes of the decomposition products to obtain the deposited electrode.

[0062] 5: After deposition, close the precursor delivery valve, maintain the substrate temperature, control the nitrogen flow rate to 50 sccm through the mass flow controller, and directly enter the reaction chamber through the bypass pipe. Purge the reaction chamber for 60 min, then turn off the substrate heating and cool to room temperature at a rate of 2℃ / min. During the cooling process, keep the nitrogen purging to obtain the cooled electrode.

[0063] 6: After cooling, the electrode was removed from the reaction chamber and transferred to a rapid thermal annealing furnace. Post-treatment annealing was performed under a nitrogen atmosphere. The annealing temperature was set to 350℃, the heating rate was 30℃ / s, and the holding time was 150s. Then, it was naturally cooled to room temperature to obtain the electrode material prepared in Comparative Example 1.

[0064] Comparative Example 2

[0065] This comparative example uses a commercially available polystyrene-ethylene oxide block copolymer (PS-b-PEO, grade: P4563, Sigma-Aldrich, Mn=15000-5000, PS segment Mn=15000, PEO segment Mn=5000, PDI≤1.1) as a pore-forming template to replace the in-situ self-pore-forming mechanism of the dual-ligand precursor in this scheme. An isothermal deposition process was used, and other components were the same as in Example 3. Process parameters were adjusted according to the requirements of the template method. The specific steps are as follows:

[0066] 1: Take a silicon / silicon dioxide substrate that has been cleaned with standard RCA. A titanium nitride bottom electrode layer with a thickness of 50nm has been pre-deposited on the substrate surface. Place the substrate in an oxygen plasma treatment chamber, set the radio frequency power to 80W, the oxygen flow rate to 50sccm, and treat with oxygen plasma for 60s to obtain a surface-activated substrate.

[0067] 2. Transfer the surface-activated substrate to the hot-wall metal-organic chemical vapor deposition reaction chamber. Place the substrate on a constant-temperature graphite base with the base temperature set to 275℃ (no temperature gradient set) and the base rotation speed set to 30 rpm. Evacuate the reaction chamber until the chamber vacuum reaches 1×10⁻⁶.-3 When the pressure reaches 100 Pa, the pumping is stopped, and then high-purity nitrogen is introduced as a carrier gas. The reaction pressure is adjusted to 100 Pa, and the reaction chamber is purged with a nitrogen flow of 50 sccm for 15 min to obtain a temperature-stable substrate.

[0068] 3: Weigh 10g of commercially available copper hexafluoroacetylacetone and 0.5g of commercially available polystyrene-polyethylene oxide block copolymer, mix the two and load them into a stainless steel bubbler. After filling in an inert atmosphere glove box, seal and transfer the mixture to a metal-organic chemical vapor deposition (MOCVD) device. Set the bubbler temperature to 65℃, use high-purity nitrogen as the carrier gas, and use a mass flow controller to precisely control the carrier gas flow rate to 20 sccm. The precursor and template mixed vapor is then transported to the reaction chamber through a 100℃ heated pipeline to obtain the precursor-template mixed vapor transport flow.

[0069] 4. After the reaction chamber pressure, substrate temperature, and bubbler temperature stabilize, open the precursor delivery valve to begin metal-organic chemical vapor deposition. During the deposition process, maintain the substrate pedestal rotation speed at 10 rpm and the reaction pressure at 50 Pa. Use a mass flow controller to control two streams of nitrogen gas. The first stream of nitrogen gas carries the precursor and template mixture vapor through the bubbler into the reaction chamber at a flow rate of 20 sccm. The second stream of nitrogen gas, as a dilution gas, enters the reaction chamber directly through a bypass pipe at a flow rate of 40 sccm. The two streams of nitrogen gas are mixed by a gas mixing device before entering the reaction chamber. The deposition time is 120 min to obtain the deposited electrode.

[0070] 5: After deposition, close the precursor delivery valve, maintain the substrate temperature, control the nitrogen flow rate to 50 sccm through the mass flow controller, and directly enter the reaction chamber through the bypass pipe. Purge the reaction chamber for 60 min, then turn off the substrate heating and cool to room temperature at a rate of 2℃ / min. During the cooling process, keep the nitrogen purging to obtain the cooled electrode.

[0071] 6: After cooling, the electrode is transferred to the ultraviolet irradiation chamber. The ultraviolet lamp wavelength is set to 254nm, the power is 100W, the irradiation distance is 5cm, and the irradiation time is 30min. The block copolymer template in the electrode is removed to obtain the ultraviolet-treated electrode.

[0072] 7: The UV-treated electrode was transferred to a rapid thermal annealing furnace and post-treatment annealing was performed under a nitrogen atmosphere. The annealing temperature was set to 350℃, the heating rate was 30℃ / s, the holding time was 150s, and then the electrode was naturally cooled to room temperature to obtain the electrode material prepared in Comparative Example 2.

[0073] Test sample preparation

[0074] The electrode materials prepared in Examples 3, 4, Comparative Example 1, and Comparative Example 2 were respectively fabricated into ReRAM memory devices. The specific steps are as follows:

[0075] 1: Take the electrode material samples (deposited on Si / SiO2 / TiN substrate, electrode size 2cm×2cm) prepared in Example 3, Example 4, Comparative Example 1 and Comparative Example 2, place them in an ultraviolet ozone cleaner for 5min to remove the organic matter adsorbed on the surface, and obtain the cleaned electrode samples.

[0076] 2: After cleaning, the electrode samples are transferred to the atomic layer deposition chamber to deposit a resistive switching layer. Tetra(ethylmethylamino)hafnium is used as the hafnium source (hafnium source tank temperature 75℃), deionized water is used as the oxygen source (water source tank temperature 25℃), and the substrate temperature is 250℃. One deposition cycle includes: 0.2s of tetra(ethylmethylamino)hafnium vapor, 8s of nitrogen purging, 0.1s of deionized water vapor, and 8s of nitrogen purging. The deposition cycle is repeated 100 times to obtain a hafnium dioxide resistive switching layer with a thickness of about 10nm. Three parallel samples are deposited for each sample.

[0077] 3: The sample after the resistive switching layer is deposited is transferred to the magnetron sputtering chamber, and the top electrode is deposited using a platinum target. The sputtering power is set to 100W, the argon pressure is 1Pa, and the deposition time is 5min. The top electrode pattern (circular electrode, diameter 100um) is defined by a mask to obtain a platinum top electrode with a thickness of 50nm, thus completing the fabrication of the ReRAM memory device. Three devices are fabricated for each example or comparative example.

[0078] 4. Place the fabricated device on the probe stage for subsequent electrical performance testing.

[0079] Switching ratio and operating voltage test

[0080] The current-voltage characteristics of the ReRAM memory devices prepared in Examples 3, 4, Comparative Examples 1 and 2 were tested using a semiconductor parameter analyzer. The test conditions were as follows: voltage scan range -1.5V to +1.5V, scan rate 0.1V / s, current limit 100uA, 10 devices were tested in each group and the average value was taken. The high-resistance current and low-resistance current were recorded, the switching ratio was calculated (switching ratio = low-resistance current / high-resistance current), and the set voltage and reset voltage were recorded.

[0081] Table 1. Test results of switching ratio and operating voltage.

[0082]

[0083] Analysis of Table 1 shows that the on / off ratios of the ReRAM memory devices prepared in Examples 3 and 4 are 85 and 92, respectively, which are significantly higher than 8 in Comparative Example 1 and 25 in Comparative Example 2. In terms of operating voltage, the set voltages of Examples 3 and 4 are 0.82V and 0.76V, respectively, and the reset voltages are -0.78V and -0.72V, respectively, which are all lower than those of Comparative Example 1 and Comparative Example 2. This indicates that the gradient porous structure formed by the in-situ self-created pores of the dual-ligand precursor in this scheme effectively confines the growth of conductive filaments, improves the on / off ratio, and reduces the operating voltage.

[0084] Cyclic tolerance test

[0085] The cycle tolerance of the ReRAM memory devices prepared in Examples 3, 4, Comparative Examples 1 and 2 was tested using a pulse generator. The test conditions were: set pulse voltage +1.0V (pulse width 100ns), reset pulse voltage -1.0V (pulse width 100ns), and 10 cycles. 9 Once, every 10 6 Read the resistance value once, record the resistance values ​​in the high resistance state and the low resistance state, calculate the resistance window (resistance window = high resistance state resistance / low resistance state resistance), and consider the device to fail when the resistance window is less than 10. Record the cycle life of each component.

[0086] Table 2. Results of Cyclic Tolerance Test

[0087]

[0088] Analysis of Table 2 shows that the cycle life of the ReRAM memory devices prepared in Examples 3 and 4 exceeds 2.5 × 10⁻⁶. 8 The sum of 3.0 × 10 8 10 times 8 After several cycles, the resistance window remained at 38 and 44; while the cycle life of Comparative Example 1 was only 8.5 × 10⁻⁶. 5 Next, 110 8 It failed before the next cycle; Comparative Example 2 had a cycle life of 4.2 × 10⁻⁶. 6 The results were significantly lower than those of the previous example, indicating that the gradient porous structure formed by the stepwise pyrolysis of ligands in this solution effectively disperses the stress during the formation / breakage of conductive filaments and improves the cycle tolerance of the device.

[0089] Retention characteristic test

[0090] The ReRAM memory devices prepared in Examples 3, 4, Comparative Example 1, and Comparative Example 2 were placed in an 85°C constant temperature oven to test their retention characteristics under high temperature conditions. The test conditions were as follows: the device was first set (written to a low resistance state), then the device was reset (written to a high resistance state), the device was placed in an 85°C environment, and the resistance value was read at regular intervals. The changes in the resistance values ​​of the high resistance state and the low resistance state with aging time were recorded. When the resistance window of the high resistance state and the low resistance state was less than 10, it was considered as failure. The retention time of each component was recorded.

[0091] Table 3, Results of retention characteristic test (85℃)

[0092]

[0093] Analysis of Table 3 shows that the ReRAM memory devices prepared in Examples 3 and 4 maintained their temperature at 85°C for more than 1.0 × 10⁻⁶ seconds. 5 s, 10 4 After s, the resistance window remained at 38 and 42; while the comparative example 1 held for only 1.2 × 10 s. 3 s, Comparative Example 2's retention time was only 8.5 × 10 s, 3 The s values ​​are significantly lower than those in the examples, indicating that the gradient porous structure formed by the stepwise pyrolysis of ligands in this scheme confines the conductive filaments in sub-5nm channels, resulting in significantly improved thermal stability.

[0094] Inter-device uniformity test

[0095] Take 50 ReRAM memory devices prepared in Example 3, Example 4, Comparative Example 1 and Comparative Example 2, test the set voltage of each device, calculate the average value and standard deviation of the set voltage, draw a histogram of the set voltage distribution, and statistically analyze the set voltage fluctuation range.

[0096] Table 4. Test results of uniformity between devices

[0097]

[0098] Analysis of Table 4 shows that the standard deviations of the set voltages of the ReRAM memory devices prepared in Examples 3 and 4 are 0.08V and 0.07V, respectively, with fluctuation ranges of 0.68-0.96V and 0.62-0.90V, respectively. The uniformity is significantly better than that of Comparative Example 1 (standard deviation 0.32V, fluctuation range 0.92-2.10V) and Comparative Example 2 (standard deviation 0.25V, fluctuation range 0.78-1.68V). This indicates that the proposed method achieves pore formation through a stepwise pyrolysis mechanism of ligands at the molecular level, resulting in uniform and gradient-distributed pore sizes, which effectively improves the consistency between devices.

[0099] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing electrode materials in a ReRAM memory, characterized in that, Using a dual-ligand copper precursor as the sole metal source, a hot-wall metal-organic chemical vapor deposition (MOCVD) system was employed. The substrate temperature gradient induced the stepwise thermal decomposition of acetylacetone and hexafluoroacetylacetone ligands in the precursor. The in-situ escape of the ligand decomposition products formed nanopores. Combined with a mild annealing treatment after deposition, the electrode structure was gradient-controlled. Unreacted precursors were recovered by condensing the exhaust gas to achieve the recycling of raw materials, resulting in a ReRAM electrode material with a gradient porous structure.

2. The method for preparing electrode materials in a ReRAM memory according to claim 1, characterized in that, Includes the following steps: S1: Take a silicon / silicon dioxide substrate that has been cleaned with standard RCA. A titanium nitride bottom electrode layer with a thickness of 50nm has been pre-deposited on the substrate surface. Place the substrate in an oxygen plasma treatment chamber, set the radio frequency power to 80W, the oxygen flow rate to 50sccm, and treat with oxygen plasma for 60s to obtain a surface-activated substrate. S2: Transfer the surface-activated substrate to the hot-wall metal-organic chemical vapor deposition reaction chamber. The substrate is placed on a graphite substrate with a temperature gradient distribution. The substrate uses independent heating control in zones, with the low-temperature zone set at 200℃ and the high-temperature zone at 350℃. The substrate rotation speed is set to 30 rpm. Evacuate the reaction chamber to a base vacuum of 1×10⁻⁶. -3 Pa, then high-purity nitrogen gas was introduced as a carrier gas, the reaction pressure was adjusted to 100 Pa, and the reaction chamber was purged with a nitrogen gas flow of 50 sccm for 15 min to obtain a temperature-stable substrate. S3: The dual-ligand copper precursor is loaded into a stainless steel bubbler. After filling in an inert atmosphere glove box, it is sealed and transferred to a metal-organic chemical vapor deposition equipment. The bubbler temperature is set to 85℃. High-purity nitrogen is used as the carrier gas. The carrier gas flow rate is precisely controlled to be 20-50 sccm using a mass flow controller. The precursor vapor is then transported to the reaction chamber through a 100℃ heating pipeline to obtain the precursor vapor transport flow. S4: After the reaction chamber pressure, substrate temperature, and bubbler temperature stabilize, open the precursor delivery valve to begin metal-organic chemical vapor deposition. During deposition, maintain the substrate pedestal rotation speed at 10-50 rpm and the reaction pressure at 50-200 Pa. Use a mass flow controller to control two streams of nitrogen. The first stream of nitrogen carries the precursor vapor into the reaction chamber via the bubbler at a flow rate of 20-50 sccm. The second stream of nitrogen acts as a dilution gas and enters the reaction chamber directly via a bypass pipe at a flow rate of 40-100 sccm. The two streams of nitrogen are mixed by a gas mixing device before entering the reaction chamber. The deposition time is 60-120 min. During deposition, use a quartz crystal micro-sky plain to monitor the deposition rate and use a residual gas analyzer to monitor the partial pressure changes of the decomposition products to obtain the deposited gradient electrode. S5: After deposition, close the precursor delivery valve, maintain the substrate temperature, control the nitrogen flow rate to 50-100 sccm through the mass flow controller, and directly enter the reaction chamber through the bypass pipe. Purge the reaction chamber for 15-60 min, and then condense and collect the unreacted precursor through a -40℃ to -20℃ cold trap. The condensed and collected precursor can be used for subsequent batches after drying. Then turn off the substrate heating and cool to room temperature at a rate of 2-10℃ / min. During the cooling process, keep the nitrogen purging to obtain the cooled gradient electrode. S6: After cooling, the gradient electrode is removed from the reaction chamber and transferred to a rapid thermal annealing furnace. Post-treatment annealing is performed under a nitrogen atmosphere. The annealing temperature is set to 350-450℃, the heating rate is 30-50℃ / s, and the holding time is 150-300s. Then, it is naturally cooled to room temperature to obtain the electrode material.

3. The method for preparing electrode materials in a ReRAM memory according to claim 2, characterized in that, The preparation method of the dual-ligand copper precursor includes the following steps: A1: In a nitrogen-protected glove box, weigh cuprous oxide and add it to a flask, then add degassed toluene. Stir magnetically at 300 rpm for 15-20 min to obtain a copper source suspension. In a fume hood, measure acetylacetone and hexafluoroacetylacetone separately. Slowly add acetylacetone dropwise to the copper source suspension at a rate of 0.5 ml / min, maintaining a stirring speed of 300 rpm during the dropwise addition. After the dropwise addition is complete, continue stirring for 15-20 min. Then, slowly add hexafluoroacetylacetone dropwise to the flask at a rate of 0.5 ml / min, maintaining a stirring speed of 300 rpm during the dropwise addition. The reaction solution gradually changes from brick red to blue, yielding a reaction mixture. A2: Place the reaction mixture at room temperature, set the stirring speed to 400-600 rpm, and stir for 2 hours. During the stirring process, use a condenser to seal and prevent air from entering and solvent from evaporating. After stirring, heat in an oil bath at a rate of 2℃ / min until the temperature reaches 50℃. After reaching 50℃, maintain the temperature for 1 hour. During the constant temperature reaction, keep the stirring speed constant and use a condenser for reflux to prevent solvent from evaporating. After the reaction is complete, allow it to cool naturally to room temperature to obtain a blue transparent solution. A3: Use a Buchner funnel to filter the blue transparent solution. The funnel is pre-lined with double layers of qualitative filter paper and 1 cm thick diatomaceous earth. The vacuum degree of filtration is set to -0.08 MPa. Collect the filtrate, discard the unreacted solid residue, and collect the filtrate in a round-bottom flask. Use a rotary evaporator to concentrate the solution under reduced pressure in a 40°C water bath. The vacuum degree of the rotary evaporator is set to -0.09 MPa, and the rotation speed is set to 80 rpm. Concentrate to 25% of the initial volume to obtain the concentrated solution. A4: Transfer the concentrate to an Erlenmeyer flask, set the magnetic stirrer speed to 200 rpm, and add n-hexane to the concentrate at a rate of 1 drop / s. A light blue precipitate will appear during the addition. After the addition is complete, keep the speed constant and continue stirring for 15 min. After stirring, seal the Erlenmeyer flask and place it in a -20℃ refrigerator for 12 h. After standing, take it out and use a Buchner funnel to collect the crystals by vacuum filtration. Set the filtration vacuum degree to -0.08 MPa. After filtration, wash the crystals three times with n-hexane pre-cooled at -20℃ to obtain the crude product. A5: Transfer the crude product to a round-bottom flask, add dichloromethane, wherein the mass-to-volume ratio of crude product to dichloromethane is 1g:3ml, stir at 200-300rpm at room temperature until the crude product is completely dissolved, then slowly add n-hexane dropwise under magnetic stirring while maintaining a constant stirring speed, with a dropping rate of 1ml / min. After the addition is complete, continue stirring for 15min, seal the round-bottom flask and place it in a -20℃ refrigerator for recrystallization for 12h. After recrystallization, remove the flask and collect the crystals by vacuum filtration using a Buchner funnel, with the filtration vacuum set to -0.08MPa. After filtration, wash the crystals twice with n-hexane pre-cooled at -20℃ to obtain the purified product. A6: Transfer the purified product to a vacuum drying oven, set the drying temperature to 25℃ and the vacuum degree to -0.09MPa, and dry for 6 hours. After drying, take it out and transfer it to a glass sample vial under nitrogen protection. Seal and store it in a glove box to obtain the dual-ligand copper precursor.

4. The method for preparing electrode material in a ReRAM memory according to claim 3, characterized in that, The mass ratio of cuprous oxide to degassed toluene in step A1 is 1:14, and the molar ratio of cuprous oxide, acetylacetone, and hexafluoroacetylacetone is 1:1:

1.

5. The method for preparing electrode material in a ReRAM memory according to claim 3, characterized in that, The volume ratio of the concentrate to n-hexane mentioned in step A4 is 1:3.

3.

6. The method for preparing electrode material in a ReRAM memory according to claim 3, characterized in that, The volume ratio of dichloromethane to n-hexane mentioned in step A5 is 1:4.

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