Cluster film memristor array device based on egain soft contact electrode and preparation method thereof

Abstract

The application relates to the technical field of cluster film device, and particularly discloses a cluster film memristor array device based on an EGaIn soft contact electrode and a preparation method thereof, wherein the preparation method comprises the following steps: designing a cross array structure layout, presetting a size and a number of mark positions in the structure layout to ensure accurate alignment and transfer of a subsequent top electrode, customizing a patterned bottom electrode glass substrate according to the structure layout; adopting a customized physical hard mask or photolithography to shield non-deposition areas, depositing a Cr / Au electrode on an electrode part of the bottom electrode by using an electron beam evaporation technology, and synchronously evaporating a Cr / Au layer at the mark positions to assist accurate alignment of the top electrode in the later period; and designing a top electrode layout; the application provides a cluster film array device based on an EGaIn soft contact electrode and a preparation method thereof, the method realizes non-destructive interface contact through a patterned transfer process, and improves the large-scale integration of the array device.

Description

Technical Field

[0001] This invention belongs to the field of cluster film device technology, specifically relating to cluster film memristor array devices based on EGaIn soft contact electrodes and their fabrication methods. Background Technology

[0002] Clustered membrane memristors, with their unique quantum size effect and controllable conductivity channel evolution characteristics, have shown great application potential in non-volatile logic operations and neuromorphic computing, and are regarded as the core basic device for building in-memory computing models and non-von Neumann computing architectures.

[0003] In the fabrication of cluster memristors, eutectic gallium indium alloy (EGaIn) is widely used in the preparation of the top electrode due to its excellent conductivity, extremely low viscosity, and good flowability. Compared with traditional vacuum evaporation processes, the soft contact interface formed by eutectic gallium indium alloy (EGaIn) can effectively prevent high-energy atoms from breaking down the cluster functional layer, thereby enabling the device to exhibit excellent electrical performance.

[0004] However, existing fabrication technologies based on eutectic gallium indium alloy (EGaIn) still have significant limitations: First, due to the liquid flowability of eutectic gallium indium alloy (EGaIn), existing technologies mostly use methods such as manually suspending droplets for single-point electrical testing, making it extremely difficult to achieve high-density array integration and large-scale manufacturing; Second, manual contact methods cannot accurately characterize and control the effective contact area between the electrode and the cluster film, resulting in drastic fluctuations in current density between different devices and a serious lack of performance consistency; In other words, in existing cluster device fabrication processes, traditional electrode evaporation is prone to breaking down the ultrathin cluster functional layer, leading to low yield, and existing liquid metal electrode testing methods are difficult to accurately control voltage and cannot achieve high-density array integration. These defects limit the transformation of cluster film memristors from laboratory single-unit research to industrial applications of high-bandwidth storage and high-speed information processing arrays. Summary of the Invention

[0005] The purpose of this invention is to provide a cluster film memristor array device based on EGaIn soft contact electrodes and its fabrication method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes includes the following steps: Step 1: Design a 3×3 crossbar structure layout. To ensure accurate alignment and transfer of the top electrode, a specific size and number of markers are preset in the structure layout. A graphic bottom electrode glass substrate is customized based on the structure layout. Step 2: Use a custom physical hard mask or photolithography to cover the non-deposition areas, and use electron beam evaporation technology to deposit Cr / Au electrodes at specific locations on the bottom electrode. Simultaneously deposit Cr / Au layers at the markers to assist in the precise alignment of the top electrode later, thus forming the bottom electrode substrate. Step 3: Design the top electrode layout and plan the markers that match the size and spacing of the bottom electrode. Using a silicon wafer as the substrate, attach a polydimethylsiloxane (PDMS) film of the same size as the carrier. Use photolithography or hard mask to define the deposition area. Then, use electron beam evaporation technology to pattern and deposit Cr / Au electrodes on the surface of the polydimethylsiloxane (PDMS). Step 4: Prepare a NaOH solution as a protective environment. Immerse the polydimethylsiloxane (PDMS) loaded with Cr / Au electrodes and the silicon wafer in a NaOH solution containing eutectic gallium indium alloy (EGaIn). Use the rigid pressure of the silicon wafer to assemble the eutectic gallium indium alloy (EGaIn) onto the surface of the Cr / Au electrode, effectively isolating oxygen and inhibiting oxidation. After assembly, the Cr / Au electrode changes from gold to silver. Eutectic gallium indium alloy (EGaIn) cannot be assembled in areas where Cr / Au is not modified. Step 5: Clean the prepared bottom electrode substrate sequentially with ethanol, acetone, isopropanol and deionized water, and then dry it with nitrogen gas for later use. Step 6: On the bottom electrode substrate, a cluster film functional layer with memristor properties is self-assembled by means of drop coating, spin coating, evaporation or solution deposition. The cleaned substrate is immersed in the functional molecule solution and left to stand in the dark for more than 48 hours to ensure that a dense cluster film functional layer is formed on the surface of the bottom electrode. After assembly, the substrate and the prepared top electrode are placed in an ultra-clean workbench for later use. Step 7: Mechanically peel the polydimethylsiloxane (PDMS) top electrode loaded with eutectic gallium indium alloy (EGaIn) from the hard, flat substrate; Step 8: Under a stereomicroscope, precise alignment is performed using the two markers. The polydimethylsiloxane (PDMS) top electrode is then transferred to the bottom electrode substrate using an alignment transfer process to complete the transfer and assembly of the top electrode, thus forming a cluster film memristor array device. Step 9: The fabricated cluster film memristor device array exhibits significant hysteresis (IV curve characteristics). Step 10: Under pulse voltage excitation, the cluster film memristor device exhibits transient current response and significant resistance state change.

[0007] Preferably, the customized specifications of the structural layout in step one are 10×10.1×0.7mm.

[0008] Preferably, the bottom electrode in step one is indium tin oxide (ITO). Preferably, in step one, the bottom electrode is patterned using photolithography or laser engraving.

[0009] Preferably, in step two, the Cr / Au electrode thicknesses are 10 / 50 nm and the size is 200 × 200 μm.

[0010] Preferably, in step three, the silicon wafer is 10×10mm in size and the deposition thickness of the Cr / Au electrode is 10 / 50nm.

[0011] Preferably, the concentration of the NaOH solution in step four is 1 mol / L.

[0012] Preferably, the cluster film memristor array device based on EGaIn soft contact electrodes is prepared by the above-described method for preparing a cluster film memristor array device based on EGaIn soft contact electrodes.

[0013] Compared with the prior art, the beneficial effects of the present invention are: The fabrication method provided by this invention achieves non-destructive electrode interface contact by pre-setting markers in the cross-array structure layout and using a patterned transfer process based on polydimethylsiloxane (PDMS) carrier. This process is carried out in a NaOH solution protective environment containing eutectic gallium indium alloy (EGaIn), which effectively isolates oxygen and inhibits oxidation. It overcomes the shortcomings of traditional vacuum evaporation, which is prone to breaking down ultrathin cluster functional layers, and the difficulty in precisely controlling the voltage and array integration of liquid metal electrodes. This is beneficial to improving the scale integration, yield and performance consistency of array devices. Attached Figure Description

[0014] Figure 1 This is the design layout of the patterned indium tin oxide in this invention; Figure 2 This is the design layout of the vapor-deposited bottom electrode in this invention; Figure 3 This is the design layout of the top Au electrode for vapor deposition in this invention; Figure 4 This is a schematic diagram of the cross-sectional structure of the clustered film memristor array device in this invention; Figure 5 This is the IV characteristic curve of the memristor array device in this invention; Figure 6 This is the pulse response diagram of the memristor array device in this invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example: Please see Figures 1-6 As shown, a method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes includes the following steps: Step 1: Design a 3×3 crossbar array structure layout. To ensure accurate alignment and transfer of the top electrode laterally, a specific size and number of markers are preset in the structure layout. The specific structure is shown in the attached figure. Figure 1 Based on the structural layout, a patterned bottom electrode glass substrate with specifications of 10×10.1×0.7mm was customized, with a bottom electrode film thickness of approximately 140nm and a surface roughness of less than 1nm. A single cluster film memristor is a two-terminal device. The bottom electrode is made of indium tin oxide (ITO). Depending on the precision requirements, the indium tin oxide (ITO) is patterned by photolithography or laser. Step 2: To facilitate wire bonding to the circuit, a Cr / Au contact layer needs to be prepared on the surface of the bottom electrode. A custom physical hard mask is used to shield the non-deposition areas. Cr / Au electrodes are deposited at specific locations on the bottom electrode using electron beam evaporation technology, with thicknesses of 10 / 50 nm (specifically, 10 nm of Cr is deposited first, followed by 50 nm of Au; depositing Cr first as an adhesion layer prevents the Au electrode from peeling off). The electrode size is 200 × 200 μm. The mask used for depositing the bottom electrode is attached. Figure 2 As shown, a Cr / Au layer is simultaneously deposited at the mark to assist in the precise alignment of the top electrode later, forming the bottom electrode substrate; Step 3: Design the top electrode layout, planning markers that match the size and spacing of the bottom electrode. Using a 10×10mm silicon wafer as the substrate, attach a polydimethylsiloxane (PDMS) film of the same size as the carrier. Use a hard mask to define the deposition area, and deposit a 10 / 50nm thick Cr / Au electrode on the PDMS surface using electron beam evaporation. The top electrode deposition mask is shown in the attached image. Figure 3 As shown; Step 4: Prepare a 1 mol / L NaOH solution as a protective environment. Immerse the polydimethylsiloxane (PDMS) loaded with Cr / Au electrodes and the silicon wafer in the NaOH solution containing eutectic gallium indium alloy (EGaIn). Use the rigid pressure of the silicon wafer to assemble the eutectic gallium indium alloy (EGaIn) onto the surface of the Cr / Au electrode, effectively isolating oxygen and inhibiting oxidation. After assembly, the Cr / Au electrode changes from gold to silver. Eutectic gallium indium alloy (EGaIn) cannot be assembled in the unmodified Cr / Au areas. Step 5: Clean the prepared bottom electrode substrate sequentially with ethanol, acetone, isopropanol and deionized water, and then dry it with nitrogen gas for later use. Step 6: On the bottom electrode substrate, a cluster film functional layer with memristor properties is self-assembled by means of drop coating, spin coating, evaporation or solution deposition. The cleaned substrate is immersed in the functional molecule solution and left to stand in the dark for more than 48 hours to ensure that a dense cluster film functional layer is formed on the surface of the bottom electrode. After assembly, the substrate and the prepared top electrode are placed in an ultra-clean workbench for later use. Step 7: Mechanically peel the polydimethylsiloxane (PDMS) top electrode loaded with eutectic gallium indium alloy (EGaIn) from the hard, flat substrate; Step 8: Under a stereomicroscope, precise alignment is performed using the two markers. The polydimethylsiloxane (PDMS) top electrode is then transferred to the bottom electrode substrate using an alignment transfer process, completing the top electrode transfer and assembly to form a cluster film memristor array device. A schematic diagram of the device's cross-sectional structure is attached. Figure 4 As shown; Step 9: The fabricated cluster film memristor device array exhibits significant hysteresis (IV curve characteristics), as shown in the attached figure. Figure 5As shown, the device fabricated in this invention exhibits significant bipolar resistive switching characteristics. The DC scan voltage range is set to -1.5V to +1.5V, the compliance current is limited to 0.1A, and the set process... Process: When the device is in the initial high-resistivity state (HRS), a negative bias is applied. As the voltage scans from 0V to -1.5V (stage I), within the range of approximately -0.7V to -1.0V, the internal conduction mechanism of the device changes, the current rises rapidly, and the device switches from the high-resistivity state (HRS) to the low-resistivity state (LRS), completing the set operation; Resistance state maintenance: During the process of the voltage sweeping to the peak value of -1.5V and returning to 0V (stage II), the device can stably maintain the low-resistivity state (LRS), exhibiting non-volatile storage characteristics; Reset process: When a positive bias is applied to the device (stage III) and exceeds the reset threshold voltage (approximately 0.9V), the internal conduction path of the device breaks, the current drops sharply by orders of magnitude, and the device switches back from the low-resistivity state (LRS) to the high-resistivity state (HRS), completing the reset operation; Step 10: Under pulsed voltage excitation, the clustered film memristor device exhibits transient current response and significant resistance state change. To further evaluate the device's application potential in high-speed memory, its resistance state switching performance under pulsed drive was tested, and the results are as follows: Figure 6 As shown, the fixed read bias voltage was set to 0.1V, the operating pulse voltage was set to ±1.5V, and the pulse width was set to 0.0001s. During the set process, a negative pulse with an amplitude of -1.5V was applied, and the device instantly responded by switching from the high impedance state (HRS) to the low impedance state (LRS), with the read current jumping from approximately 10⁻⁵A to approximately 3×10⁻⁴A. During the reset process, a positive pulse with an amplitude of +1.5V was applied, and the device current quickly dropped back to the 10⁻⁵A level, successfully restoring to the original high impedance state (HRS). The test curves show that the device can achieve precise and rapid switching between high and low impedance states under continuous pulse stimulation, fully demonstrating the device's excellent pulse response characteristics and non-volatile storage capability.

[0017] The fabrication method provided by this invention achieves non-destructive electrode interface contact by pre-setting markers in the cross-array structure layout and using a patterned transfer process based on polydimethylsiloxane (PDMS) carrier. This process is carried out in a NaOH solution protective environment containing eutectic gallium indium alloy (EGaIn), which effectively isolates oxygen and inhibits oxidation. It overcomes the shortcomings of traditional vacuum evaporation, which is prone to breaking down ultrathin cluster functional layers, and the difficulty in precisely controlling the voltage and array integration of liquid metal electrodes. This is beneficial to improving the scale integration, yield and performance consistency of array devices.

[0018] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes, characterized in that, Includes the following steps: Step 1: Design the cross-array structure layout. To ensure the accurate alignment and transfer of the top electrode, the layout is pre-marked with size and quantity markers. Based on the layout, a graphic bottom electrode glass substrate is customized. Step 2: Use a custom physical hard mask or photolithography to cover the non-deposition areas, and use electron beam evaporation technology to deposit Cr / Au electrodes on the electrode sites of the bottom electrode. Simultaneously deposit Cr / Au layers at the marker sites to assist in the precise alignment of the top electrode later, forming the bottom electrode substrate. Step 3: Design the top electrode layout and plan the marker positions that match the size and spacing of the bottom electrode. Using a silicon wafer as the substrate, attach a polydimethylsiloxane film of the same size as the carrier. Use photolithography or hard mask to define the deposition area. Then, use electron beam evaporation technology to pattern and deposit Cr / Au electrodes on the polydimethylsiloxane surface. Step 4: Prepare a NaOH solution as a protective environment. Immerse the polydimethylsiloxane loaded with Cr / Au electrode and the silicon wafer in a NaOH solution containing eutectic gallium indium alloy. Use the rigid pressure of the silicon wafer to assemble the eutectic gallium indium alloy onto the surface of the Cr / Au electrode, effectively isolating oxygen and inhibiting oxidation. Step 5: Clean the prepared bottom electrode substrate sequentially with ethanol, acetone, isopropanol and deionized water, and then dry it with nitrogen gas for later use. Step 6: On the bottom electrode substrate, a cluster film functional layer with memristor properties is self-assembled by drop coating, spin coating, evaporation or solution deposition. Step 7: Mechanically peel the polydimethylsiloxane top electrode loaded with eutectic gallium indium alloy from the hard, flat substrate. Step 8: Under a stereomicroscope, precise alignment is performed using the markers on both sides. The polydimethylsiloxane top electrode is then covered onto the surface of the bottom electrode substrate using an alignment transfer process, completing the transfer and assembly of the top electrode to form a cluster film memristor array device. Step 9: The fabricated cluster film memristor device array exhibits significant hysteresis. Step 10: Under pulse voltage excitation, the cluster film memristor device exhibits transient current response and significant resistance state change.

2. The method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes according to claim 1, characterized in that: The customized specifications for the structural layout in step one are 10×10.1×0.7mm.

3. The method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes according to claim 1, characterized in that: In step one, the bottom electrode is indium tin oxide.

4. The method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes according to claim 1, characterized in that: In step one, the bottom electrode is patterned using photolithography or laser engraving.

5. The method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes according to claim 1, characterized in that: In step two, the Cr / Au electrodes have thicknesses of 10 / 50 nm and dimensions of 200 × 200 μm.

6. The method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes according to claim 1, characterized in that: In step three, the silicon wafer is 10×10mm in size, and the deposition thickness of the Cr / Au electrode is 10 / 50nm.

7. The method for fabricating a cluster film memristor array device based on EGaIn soft contact electrodes according to claim 1, characterized in that: In step four, the concentration of the NaOH solution is 1 mol / L.

8. A cluster film memristor array device based on EGaIn soft contact electrodes, characterized in that: The cluster film memristor array device based on EGaIn soft contact electrodes is prepared by the method for preparing a cluster film memristor array device based on EGaIn soft contact electrodes as described in any one of claims 1-7.

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