Nanometer structure channel planar electrode and preparation method

Abstract

This invention relates to the field of resistive switching memory (RSM) fabrication technology, specifically to a universal nanostructured channel planar electrode and its fabrication method. It introduces a low-cost AAO nanostructure fabrication process into the planar electrode channel, reducing the effective spacing between the left and right electrodes by controlling the nanostructure size, thus enabling the fabrication of high-performance devices. This invention solves the dependence on fine processing methods such as EBL (Extended Laser Brush) while allowing the electrode spacing to be controlled at the micrometer level, enabling the fabrication of the left and right electrodes using traditional photolithography. Since the width of the channel region is at the micrometer level, and the alignment accuracy of photolithography is 0.5 μm, the influence of alignment errors in the second and third photolithography stages can be eliminated. Furthermore, by omitting some steps, the fabrication of a universal traditional planar electrode can also be achieved. Based on this, this invention achieves independent and controllable fabrication of nanostructured channel planar electrodes, obtaining a universal nanostructured channel planar electrode.

Description

Technical Field

[0001] This invention relates to the field of resistive switching memory fabrication technology, specifically to a general-purpose nanostructured channel planar electrode and its fabrication method. Background Technology

[0002] Since the publication of "The Miss Memristor Found" by RS Williams et al. from HP Laboratories in Nature in 2008, confirming the memristor phenomenon in nanoelectronic systems, resistive random access memory (memristors) has attracted much attention in fields such as information storage, in-memory computing, and neuromorphic computing. The demand for massive data storage and retrieval in the era of big data has led to the rise of the memristor field. Memristors possess advantages such as non-volatility, high-speed switching, high durability, high-density integration, and CMOS process compatibility. Memristors have a simple "electrode-dielectric-electrode" structure, and the electrodes, as an indispensable component of the memristor structure, not only conduct voltage but also play a crucial role in the device's resistance switching performance. Therefore, research on electrode fabrication methods is critical.

[0003] The performance of memristors is closely related to the electrode materials and dimensions. To address the issue of metal particle damage during electrode fabrication, many novel electrode processing methods have emerged, such as planar electrodes and nanostructured patterned electrodes. Planar devices are simpler to fabricate than vertical devices, and because the electrodes do not overlap, material damage can be effectively avoided. Nanostructured patterned electrodes help reduce operating voltage and improve device stability. These novel electrode processing methods can significantly improve device performance.

[0004] For general-purpose electrodes, the left electrode, channel nanostructure electrode, and right electrode must be fabricated independently and controllably to meet the needs of various applications, such as situations where the left and right electrodes are "inert-inert," "inert-active," or "active-active," respectively. This requires that the materials of the left and right electrodes can be different, making the use of overlay photolithography (with an overlay accuracy typically of 0.5 μm) unavoidable. Consequently, the processing accuracy of the spacing between the left and right electrodes cannot be guaranteed. However, current methods typically employ fine processing techniques such as EBL, which are costly, have low throughput, and are difficult to implement practically. Furthermore, in the fabrication of channel nanostructures, AAO (Al₂O₃) is miscible with acids and bases. Ensuring that AAO is removed after the process while retaining the active electrodes such as Al and Cu becomes another bottleneck. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a universal nanostructured channel planar electrode, which aims to achieve the preparation of a universal nanostructured channel planar electrode with independent and controllable individual electrodes, thereby meeting the requirements of non-solution removal and precise control of electrode size in AAO.

[0006] To achieve the above objectives, the present invention provides a method for fabricating a universal nanostructured channel planar electrode, comprising the following steps:

[0007] Step 1: Using an insulating material as a substrate, nanostructured electrodes are introduced into the planar structure using the drainage method;

[0008] Step 2: The substrate is cleaned and hydrophilized, and then an AAO double-pass film is obtained using a drainage method.

[0009] Step 3: Perform the first photolithography on the substrate to obtain the AAO dual-channel thin film, and use magnetron sputtering to deposit metal to obtain the bottom electrode of the nanochannel;

[0010] Step 4: Sputter SiO2 onto the bottom electrode of the nanochannel to protect the bottom electrode of the channel;

[0011] Step 5: Remove the photoresist remaining from the first photolithography by using a solvent from the bottom electrode of the channel protected in Step 4, and then use RIE or ICP to dry etch the AAO dual-channel thin film to obtain the space for depositing the left and right electrodes.

[0012] Step 6: Perform a second photolithography on the space between the obtained left and right electrodes, then perform metal deposition on the left / right electrodes, and remove the photoresist; perform a third photolithography, then perform metal deposition on the right / left electrodes, and remove the photoresist; to obtain a nanostructured channel planar electrode with an AAO dual-pass film;

[0013] Step 7: Apply adhesive tape evenly to the surface of the obtained nanostructured channel planar electrode with AAO dual-channel film, and then peel off the tape to remove AAO, thus obtaining the nanostructured channel planar electrode.

[0014] Optionally, during the execution of step 2, the AAO dual-channel thin film is prepared by anodic oxidation of Al, and the pore size and period are continuously adjustable from 15nm to 1μm.

[0015] Optionally, during the process of sputtering SiO2 onto the bottom electrode of the nanochannel, an angled sputtering method is used to ensure that the bottom electrode of the channel does not contact the top SiO2, while the top SiO2 can seal the nanopores of the AAO dual-channel thin film.

[0016] Optionally, chlorine-based gas can be used as the etching gas during the dry etching process.

[0017] Optionally, the photolithography and dry etching processes in the execution steps are both general processes, and both the AAO dual-channel film and Al are insoluble in weak alkalis.

[0018] Optionally, the metallic material in the deposited metal and the left / right electrode metal includes any one of Pt, Au, Al and Ag.

[0019] Optionally, the magnetron sputtering metal deposition operation in step 3 can be omitted during the process to obtain a general-purpose planar electrode without nanostructures.

[0020] The present invention also proposes a universal nanostructured channel planar electrode, which is prepared by the preparation method of the universal nanostructured channel planar electrode, including a left electrode, a right electrode, a channel nanostructured electrode and an insulating substrate. The left electrode, the right electrode and the channel nanostructured electrode are all disposed on the insulating substrate. The left electrode and the right electrode are symmetrically arranged, and the channel nanostructured electrode is arranged between the left electrode and the right electrode.

[0021] This invention provides a universal nanostructured channel planar electrode and its fabrication method. It introduces a low-cost AAO nanostructure fabrication process into the planar electrode channel, and by controlling the size of the nanostructure, reduces the effective spacing between the left and right electrodes, thereby achieving the fabrication of high-performance devices.

[0022] This invention employs a channel nanostructure electrode scheme. The introduction of the nanostructure electrode shortens the effective distance between the upper and lower electrodes of the device, while the formation of conductive filaments becomes more concentrated and their positions more fixed, resulting in a more uniform and lower set and reset voltage. The distance between the left and right electrodes can be effectively controlled by adjusting the period and aperture of the channel nanostructure.

[0023] This invention addresses the dependency on fine processing techniques such as EBL (Extended Laser Lining). Simultaneously, the electrode spacing only needs to be controlled at the micrometer level, allowing for the fabrication of the left and right electrodes using traditional photolithography. Since the width of the channel region is at the micrometer level, and the alignment precision of photolithography is 0.5 μm, the influence of alignment errors from the second and third photolithography steps can be eliminated. Furthermore, by omitting some steps, the fabrication of general-purpose conventional planar electrodes can be achieved. Building upon this, this invention enables the independent and controllable fabrication of nanostructured channel planar electrodes, resulting in general-purpose nanostructured channel planar electrodes. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1This is a schematic flowchart of the steps involved in the fabrication of a general-purpose nanostructured channel planar electrode according to the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of a general-purpose nanostructured channel planar electrode according to the present invention.

[0027] Figure 3 This is a top view of a general-purpose nanostructured channel planar electrode according to the present invention.

[0028] Figure 4 This is a schematic diagram of the fabrication process of a general nanostructured channel planar electrode according to a specific embodiment of the present invention.

[0029] 1-Left electrode, 2-Right electrode, 3-Channel nanostructure electrode, 4-Insulating substrate. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] Please see Figure 1 This invention provides a method for fabricating a universal nanostructured channel planar electrode, comprising the following steps:

[0032] S1: Using an insulating material as a substrate, nanostructured electrodes are introduced into a planar structure using the drainage method;

[0033] S2: The substrate is cleaned and hydrophilized, and then an AAO dual-pass film is obtained by using a drainage method.

[0034] S3: Perform the first photolithography on the substrate to obtain the AAO double-channel thin film, and use magnetron sputtering to deposit metal to obtain the bottom electrode of the nanochannel;

[0035] S4: Sputter SiO2 onto the bottom electrode of the nanochannel to protect the bottom electrode of the channel;

[0036] S5: The bottom electrode of the channel protected by step S4 is used to remove the photoresist remaining from the first photolithography by solvent, and then the AAO dual-channel thin film is dry etched by RIE or ICP to obtain the space for depositing the left and right electrodes.

[0037] S6: Perform a second photolithography on the space obtained for the deposition of the left and right electrodes, then perform metal deposition on the left / right electrodes, and remove the photoresist; perform a third photolithography, then perform metal deposition on the right / left electrodes, and remove the photoresist; obtain a nanostructured channel planar electrode with an AAO dual-pass film;

[0038] S7: The obtained nanostructured channel planar electrode with AAO dual-pass film is evenly attached to the surface with adhesive tape, and then the tape is removed to remove AAO, thus obtaining the nanostructured channel planar electrode.

[0039] Furthermore, in step S2, an AAO double-pass film is obtained by the drainage method. Since the AAO is prepared by the anodic oxidation of Al, the pore size and period are continuously adjustable from 15nm to 1μm, and the thickness of the AAO film can also be precisely controlled to tens of nanometers and above.

[0040] In step S4, SiO2 is sputtered to protect the bottom electrode of the channel. An angled sputtering method is used to ensure that the bottom electrode of the channel does not come into contact with the top SiO2, while the top SiO2 can seal the AAO nanopores to protect the Al electrode of the channel in the subsequent dry etching process.

[0041] In step S5, a chlorine-based gas such as BCl3 is typically used as the etching gas.

[0042] Al₂O₃ + 3BCl₃ = 2AlCl₃ + 3BOCl₃

[0043] Under these conditions, the SiO2 capping layer has a high etching selectivity for AAO, and the dry etching process has excellent directionality, thus ensuring that the SiO2 capping layer thickness changes little and the lateral dimensions are not affected while removing AAO.

[0044] Furthermore, both photolithography and dry etching in the steps are common processes, and neither AAO nor Al is soluble in weak alkali.

[0045] The metallic materials in the deposited metal and the left / right electrode metal can generally be Pt, Au, Al, Ag, etc.

[0046] For details, please refer to Figure 2 and Figure 3 The present invention also proposes a universal nanostructured channel planar electrode, which is prepared by the preparation method of the universal nanostructured channel planar electrode, including a left electrode 1, a right electrode 2, a channel nanostructured electrode 3 and an insulating substrate 4. The left electrode 1, the right electrode 2 and the channel nanostructured electrode 3 are all disposed on the insulating substrate 4. The left electrode 1 and the right electrode 2 are symmetrically arranged, and the channel nanostructured electrode 3 is arranged between the left electrode 1 and the right electrode 2.

[0047] like Figure 3As shown, in the channel, conductive filaments only appear in the parts not filled by the nanostructure; therefore, the effective channel width is d1+d2+d3. Devices fabricated using this method exhibit low cost, low damage, low power consumption, high process compatibility, high cycle stability, and high reliability.

[0048] Furthermore, the present invention will be further illustrated through a specific embodiment, the process of which is as follows: Figure 4 As shown:

[0049] 1. Using SiO2 (200nm) / Si as the insulating substrate, the SiO2 (200nm) / Si substrate was ultrasonically cleaned for 10 minutes sequentially with acetone, ethanol, and deionized water, followed by cleaning with piranha solution for 15 minutes to form a hydrophilic surface. AAO porous nanostructures with continuously tunable pore size and period (15nm~1μm) were prepared by Al anodizing using a water displacement method. Figure 4 As shown in (a).

[0050] 2. After transferring the AAO substrate in step 1, drop 9920 photoresist onto the AAO. The first stage rotation speed is 500 rad / min for 5 seconds, and the second stage rotation speed is 4000 rad / min for 1 minute. Bake at 130°C for 90 seconds, remove the photoresist, expose for 25 seconds, develop for 40 seconds, rinse with deionized water for 30 seconds, and dry the target substrate with nitrogen. Bake again for 90 seconds to solidify the film, obtaining a fixed channel spacing, as shown in the diagram. Figure 4 As shown in (b), metallic Al was then sputtered using magnetron sputtering to obtain the bottom electrode of the nanochannel, with the structure as shown. Figure 4 As shown in (c).

[0051] 3. The target substrate with the bottom electrode of the nanochannel obtained in step 2 is removed and subjected to tilt-angle sputtering of SiO2, resulting in the structure shown below. Figure 4 As shown in (d), the bottom electrode of the protected channel is protected from the effects of subsequent dry etching.

[0052] 4. Remove the bottom electrode of the channel after the three-step protection process, remove the remaining photoresist with acetone, and then clean it with ethanol and deionized water. The structure is as follows. Figure 4 As shown in (e), dry etching with Cl2+BCl3 gas was then used to obtain the space for the deposition of the left and right electrodes, with the structure as shown in [image / description]. Figure 4 As shown in (f).

[0053] 5. After obtaining the space for depositing the left and right electrodes using step 4, perform a second photolithography (the photolithography process parameters and steps are the same as the first time), and the structure is as follows. Figure 4 As shown in (g), Ag metal is then sputtered using magnetron sputtering, and the remaining photoresist is removed using acetone to obtain the left electrode, with the structure shown in [image missing]. Figure 4As shown in (h).

[0054] 6. After obtaining the left electrode in step 5, perform a third photolithography step (the photolithography process parameters and steps are the same as the first step), the structure is as follows. Figure 4 As shown in (i), Ag metal is then sputtered using magnetron sputtering, and the remaining photoresist is removed using acetone to obtain a planar nanochannel electrode with AAO, as shown in the figure. Figure 4 As shown in (j).

[0055] 7. Following step 6, a planar nanostructured channel electrode with AAO is obtained by pressing high-temperature tape or 3M470 electroplated tape onto the AAO film to ensure full contact between the tape and the AAO film. The tape is then gently removed, resulting in a planar nanostructured channel electrode on the target substrate surface. The structure is as follows: Figure 4 As shown in (k).

[0056] Furthermore, the insulating substrate in this invention can be glass, sapphire, mica, etc.; the photolithography process parameters and steps can also be adjusted, but the parameters currently used have good results.

[0057] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for fabricating a nanostructured channel planar electrode, characterized in that, Includes the following steps: Step 1: The substrate is cleaned and hydrophilized using an insulating material as the substrate, and then an AAO double-pass film is obtained using a drainage method. The AAO double-pass film is prepared by anodizing Al. Step 2: Perform the first photolithography on the substrate to obtain the AAO dual-channel thin film, and use magnetron sputtering to deposit metal to obtain the bottom electrode of the nanochannel; Step 3: Sputter SiO2 onto the bottom electrode of the nanochannel to protect the bottom electrode of the channel; Step 4: Remove the photoresist remaining from the first photolithography by using a solvent from the bottom electrode of the channel protected in Step 3, and then use RIE or ICP to dry etch the AAO dual-channel thin film to obtain the space for depositing the left and right electrodes. Step 5: Perform a second photolithography on the space obtained for the deposition of the left and right electrodes, then perform metal deposition on the left or right electrodes, and remove the photoresist; A third photolithography step is performed, followed by metal deposition on either the right or left electrode, and then the photoresist is removed. A nanostructured channel planar electrode with an AAO dual-pass film was obtained; Step 6: Apply adhesive tape evenly to the surface of the obtained nanostructured channel planar electrode with AAO dual-channel film, then peel off the tape to remove AAO, thus obtaining the nanostructured channel planar electrode; the nanostructured channel planar electrode includes a left electrode, a right electrode, a channel nanostructure electrode, and an insulating substrate. The left electrode, the right electrode, and the channel nanostructure electrode are all disposed on the insulating substrate. The left electrode and the right electrode are symmetrically arranged, and the channel nanostructure electrode is arranged between the left electrode and the right electrode.

2. The method for fabricating a nanostructured channel planar electrode as described in claim 1, characterized in that, During the execution of step 1, the aperture and period of the AAO dual-pass film are continuously adjustable from 15nm to 1μm.

3. The method for fabricating a nanostructured channel planar electrode as described in claim 2, characterized in that, During the process of sputtering SiO2 onto the bottom electrode of the nanochannel, an angled sputtering method is used to ensure that the bottom electrode of the channel does not come into contact with the top SiO2, while the top SiO2 can seal the nanopores of the AAO dual-channel thin film.

4. The method for fabricating a nanostructured channel planar electrode as described in claim 3, characterized in that, In the dry etching process, chlorine-based gas is used as the etching gas.

5. The method for fabricating a nanostructured channel planar electrode as described in claim 4, characterized in that, In the execution steps, both the AAO double-pass film and Al are insoluble in weak bases.

6. The method for fabricating a nanostructured channel planar electrode as described in claim 5, characterized in that, The metal material in the magnetron sputtered deposited metal, or the left or right electrode metal, includes any one of Pt, Au, Al, and Ag.

7. A nanostructured channel planar electrode, prepared by the preparation method described in claim 1.

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