Nano-fluid memristor preparation method based on nano milling array nano-channel structure

Abstract

The invention discloses a nanofluid memristor preparation method based on a nano milling array nano channel structure, and belongs to the technical field of memristor preparation. The method comprises the following steps: preparing an upper layer micro-channel by adopting an ultraviolet lithography technology; a flexible mask is prepared on the surface of a silicon wafer through ultraviolet lithography, photoresist in a non-exposure area is dissolved and falls off, a silicon substrate is exposed, a micro-channel structure is obtained on the silicon substrate through processing, and the silicon substrate with the micro-channel is obtained after the photoresist is completely removed; the nanometer milling is realized by an atomic force microscope system and a two-dimensional piezoelectric ceramic actuator; carrying out transfer printing by taking the silicon wafer with the convex micro-channel as a template to obtain a PDMS (Polydimethylsiloxane) wafer with the micro-channel; carrying out secondary transfer printing by taking the silicon wafer with the nano channel array as a template to obtain a PDMS (Polydimethylsiloxane) wafer with a nano channel and a micron channel; and bonding the two PDMS sheets in an oxygen plasma treatment manner. The method is simple in process, rapid, efficient, stable in structure, good in consistency, capable of being copied on a large scale and good in biocompatibility.

Description

Technical Field

[0001] The invention belongs to the technical field of memristor preparation, and in particular relates to a method for preparing a nanofluid memristor based on a nano-milling array nanochannel structure. Background Art

[0002] The current computer system is developed based on the von Neumann computing architecture, with a high degree of separation between computing and storage, which results in the processor being unable to fully utilize its computing power. Compared with other hardware, memristors with the characteristics of non-volatility of resistance can well match neural networks and realize neuromorphic computing. Nanofluid memristors have the advantages of simple preparation process, durability and good retention characteristics, and have broad application prospects in future neuromorphic computing.

[0003] The geometry has a significant impact on the electrical properties of nanochannels. When the characteristic size of a nanochannel is close to the Debye length, it will cause the double electric layer of the nanochannel to overlap, affecting the ion transport in the nanochannel, resulting in a variety of phenomena. Therefore, high-quality processing of size-controllable nanochannels is of great significance for improving the performance of fluid memristors. At present, the methods suitable for preparing fluid memristors based on nanofluidic devices mainly include electron beam lithography (EBL), focused ion beam lithography (FIB), nanoimprint lithography (NIL) and self-assembly technology. EBL and FIB can etch silicon-based materials with a resolution as low as 10nm, but they are expensive. The NIL process requires heating, and the thermal expansion of plastic materials will cause dimensional errors during the pattern transfer process. Using AFM nano-milling silicon substrates can obtain nanochannels with controllable size and good consistency, and using them as templates for transfer printing can quickly prepare nanofluidic memristors. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of high cost and poor precision of existing nanofluidic device preparation methods, and to provide a nanofluidic memristor preparation method based on nano-milling array nanochannel structure.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a nanofluid memristor based on a nano-milling array nanochannel structure, the method comprising:

[0007] Step 1: Microchannel structure processing: The upper microchannel is prepared by ultraviolet lithography. After exposure and development, a convex microchannel structure is obtained. The lower microchannel is prepared by preparing a flexible mask on the silicon wafer surface through ultraviolet lithography. The photoresist in the non-exposed area is dissolved and detached to expose the silicon substrate. 6 and O 2Reactive ion etching (RIE) is performed on the silicon substrate using a mixed gas of , and a microchannel structure is obtained on the silicon substrate. After all the photoresist is removed using Remover PG stripping solution, a silicon substrate with microchannels is obtained;

[0008] Step 2: Nanochannel structure processing: Nano-milling processing is achieved by a combination of a commercial atomic force microscope (AFM) system and a two-dimensional piezoelectric ceramic actuator; the sample rotates during nano-milling, and processing is achieved through relative motion; the rotation of the sample is completed by the two-dimensional piezoelectric ceramic actuator driven by a sinusoidal signal with a phase difference of 90°, and the movement of the sample in the horizontal plane is achieved by the composite movement of the X and Y directions; there is no material accumulation at the edge of the nano-groove, which is suitable for the preparation of nanofluid memristors. Through AFM nano-milling, a nanochannel array is processed on the silicon substrate with microchannels in step 1;

[0009] Step 3: Structure transfer: After transferring the silicon wafer with convex microchannels as a template, a PDMS sheet with microchannels can be obtained; after transferring the silicon wafer with nanochannel array as a template, the PDMS obtained by the first transfer is used as a template, poured into the PDMS and heated on a hot plate at 120°C for 30 minutes, and the cured PDMS is peeled off from the mold to obtain a PDMS sheet with nanochannels and microchannels;

[0010] Step 4: Bonding: The PDMS sheet with microchannels and the PDMS sheet with nanochannels and microchannels in step 3 are bonded by oxygen plasma treatment.

[0011] Furthermore, in step 1, in the ultraviolet lithography technology, a negative photoresist (SU-82015) produced by MicroChem, USA, was used, and the photoresist was first spin-coated on the silicon substrate at a speed of 500 r / min for 5 s, and then spin-coated at a speed of 4000 r / min for 120 s.

[0012] Furthermore, in step 2, the driving voltages in the X and Y directions are 100 V and 150 V, respectively, and the normal load and driving frequency are 12 μN and 2000 Hz, respectively.

[0013] Furthermore, in step three, the material used for transfer is Sylgard 184 polydimethylsiloxane (PDMS) produced by Dow Corning, USA, and the mass ratio of PDMS to curing agent is selected as 10:1; the PDMS and curing agent are evenly stirred, and then poured on the mold and allowed to stand until all the bubbles in the PDMS are removed; then the mold after the bubbles are removed is placed on a hot plate at 120°C and heated for 30 minutes; finally, the PDMS with the replicated structure is gently peeled off from the mold to obtain a PDMS sheet with a structure.

[0014] Furthermore, in step 4, the prepared PDMS sheet was treated with an oxygen plasma cleaning machine produced by Diener Electronic of Germany at a power of 80 W for 30 seconds, and the PDMS sheet with the microchannel array and the PDMS sheet with the nanochannel array were bonded according to the alignment mark, and then the bonded PDMS sheet was placed on a hot plate at 95° C. for 20 minutes. The actual fluid memristor is shown in FIG. Figure 5 shown.

[0015] The beneficial effects of the present invention compared with the prior art are as follows: the method for preparing nanofluid memristor has the advantages of simple process, rapid and efficient, stable structure, good consistency, large-scale replication, good biocompatibility, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Prepare a flow chart for nanofluidic memristors;

[0017] Figure 2 This is a schematic diagram of the structure of the nanofluid memristor;

[0018] Figure 3 Schematic diagram of the AFM-based vibration-assisted nanofabrication system;

[0019] Figure 4 This is a typical nanogroove secondary transfer AFM topography image;

[0020] Figure 5 This is a physical picture of the fluid memristor;

[0021] Figure 6 This is a diagram of the IV measurement results of the fluid memristor. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0023] The present invention mainly uses an atomic force microscope (AFM) as a processing device to perform a scratching process on the surface of a silicon wafer with microchannels to obtain nanogrooves, uses the structure on the surface of the silicon wafer as a template, performs two transfers with PDMS, thereby obtaining PDMS with microchannels and nanochannels, and bonds the PDMS with another PDMS with microchannels to obtain a nanofluid memristor with a nanochannel array.

[0024] Embodiment 1:

[0025] The specific implementation method of preparing the nanofluid memristor is as follows:

[0026] (1) Microchannel structure processing: The preparation process of nanofluid memristor is as follows Figure 1 As shown, (a1)-(a3) show the production process of the upper microchannel, and (b1)-(b4) show the production process of the lower microchannel and nanochannel. The preparation of the upper microchannel is achieved by ultraviolet lithography technology, using negative photoresist (SU-82015) produced by MicroChem, USA. The photoresist is first spin-coated on the silicon substrate at a speed of 500r / min for 5s, and then spin-coated at a speed of 4000r / min for 120s. After the process of exposure and development, a convex microchannel structure is obtained, as shown in FIG. Figure 1 (a1) is shown. The preparation of the lower microchannel is as follows Figure 1 As shown in (b1)-(b2), a flexible mask is prepared on the surface of a silicon wafer by UV lithography. The photoresist in the non-exposed area dissolves and falls off, exposing the silicon substrate. 6 and O 2 The mixed gas is used for RIE etching to obtain a microchannel structure on the silicon substrate.

[0027] (2) Nanochannel structure processing: Nano-milling processing platform such as Figure 3 As shown, it is mainly realized by a combination of a commercial atomic force microscope (AFM) system and a piezoelectric ceramic actuator. During the nano-milling process, the sample rotates and processing is achieved through relative motion. The rotational motion of the sample is completed by a two-dimensional piezoelectric ceramic actuator driven by a sinusoidal signal with a phase difference of 90°, and the movement of the sample in the horizontal plane is achieved by the synthetic motion in the X and Y directions. The driving voltages in the X and Y directions are 100V and 150V, respectively, and the normal load and driving frequency are 12μN and 2000Hz, respectively. There is no material accumulation at the edge of the nano-groove, which is suitable for the preparation of nanofluid memristors. Through AFM nano-milling, on a silicon substrate with a microchannel structure ( Figure 1 b2) to obtain a nanochannel array, such as Figure 1 (b3) and Figure 2 shown.

[0028] (3) Structural transfer: The material used for transfer is Sylgard 184 produced by DowCorining, USA, and the mass ratio of PDMS to curing agent is selected as 10:1. Stir the PDMS and curing agent evenly, then pour them on the mold and let them stand until all the bubbles in the PDMS are removed. Then, place the mold after the bubbles are removed on a hot plate at 120°C and heat for 30 minutes. Finally, gently peel off the PDMS with the replicated structure from the mold to obtain a PDMS sheet with a structure. Figure 1 As shown in (a2)-(a3), after the silicon wafer with convex microchannels is used as a template for transfer printing, PDMS with microchannels can be obtained. The secondary transfer process is the same as the primary transfer process, as shown in Figure 1As shown in (b4), the silicon wafer with the nanochannel array (b3) is used as a template for a transfer, and the PDMS obtained by the first transfer is used as a template. After pouring PDMS, it is placed on a hot plate at 120°C and heated for 30 minutes. The cured PDMS is peeled off from the mold to obtain a PDMS sheet with nanochannels and microchannels (b4). AFM images of grooves processed by AFM nano-milling, convex structures obtained by the first transfer of PDMS, and grooves obtained by the second transfer of PDMS are shown in Figure 4 shown.

[0029] (4) Bonding: The bonding of the PDMS sheet is carried out by oxygen plasma treatment. The prepared PDMS chip is treated with an oxygen plasma cleaning machine produced by Diener Electronic of Germany at a power of 80W for 30 seconds. The PDMS is bonded according to the alignment mark, and then the bonded PDMS sheet is placed on a hot plate at 95°C for 20 minutes. The actual fluid memristor is shown in FIG. Figure 5 shown.

[0030] (5) Electrical performance test: A high-precision electrometer (Keithley 6430) produced by Keithley, USA, was used to measure the current values ​​on both sides of the channel. The voltage increment interval was 1V, and each voltage increase lasted for 2s. The electrolyte solution was a mixture of 1mM KCl solution and ionic liquid BmimPF6. Typical results of nanofluid memristor IV measurement are shown in Figure 2. Figure 6 As shown, it indicates that the prepared nanofluid memristor has good memristive performance.

Claims

1. A method for preparing a nanofluidic memristor based on a nano-milling array nanochannel structure, characterized in that: The method is: Step 1: Microchannel structure processing: The upper microchannel is prepared by ultraviolet lithography technology. After exposure and development, a convex microchannel structure is obtained. The lower microchannel is prepared by preparing a flexible mask on the surface of the silicon wafer by ultraviolet lithography. The photoresist in the non-exposed area is dissolved and peeled off to expose the silicon substrate. A mixed gas of SF6 and O2 is used for reactive ion etching to obtain a microchannel structure on the silicon substrate. After all the photoresist is removed using Remover PG degumming liquid, a silicon substrate with a microchannel is obtained. Step 2: Nanochannel structure processing: Nano-milling processing is achieved by a combination of a commercial atomic force microscope system and a two-dimensional piezoelectric ceramic actuator; during the nano-milling process, the sample rotates and processing is achieved through relative motion; the rotational motion of the sample is completed by the two-dimensional piezoelectric ceramic actuator driven by a sinusoidal signal with a phase difference of 90°, and the movement of the sample in the horizontal plane is achieved by the composite motion of the X and Y directions; through AFM nano-milling, a nanochannel array is processed on the silicon substrate with microchannels in step 1; Step 3: Structure transfer: After transferring the silicon wafer with convex microchannels as a template, a PDMS sheet with microchannels can be obtained; after transferring the silicon wafer with nanochannel array as a template, the PDMS obtained by the first transfer is used as a template, poured into the PDMS and heated on a hot plate at 120°C for 30 minutes, and the cured PDMS is peeled off from the mold to obtain a PDMS sheet with nanochannels and microchannels; Step 4: Bonding: The PDMS sheet with microchannels and the PDMS sheet with nanochannels and microchannels in step 3 are bonded by oxygen plasma treatment.

2. The method for preparing a nanofluidic memristor based on a nano-milling array nanochannel structure according to claim 1, characterized in that: In step 1, in the ultraviolet lithography technology, negative photoresist is used, and the photoresist is first spin-coated on the silicon substrate at a speed of 500 r / min for 5 seconds, and then spin-coated at a speed of 4000 r / min for 120 seconds.

3. The method for preparing a nanofluidic memristor based on a nano-milling array nanochannel structure according to claim 1, characterized in that: In step 2, the driving voltages in the X and Y directions are 100 V and 150 V, respectively, and the normal load and driving frequency are 12 μN and 2000 Hz, respectively.

4. The method for preparing a nanofluidic memristor based on a nano-milling array nanochannel structure according to claim 1, characterized in that: In step three, the material used for transfer is polydimethylsiloxane, and the mass ratio of PDMS to curing agent is selected as 10:1; the PDMS and curing agent are evenly stirred, then poured onto the mold and allowed to stand until all the bubbles in the PDMS are removed; the mold after the bubbles are removed is then placed on a hot plate at 120°C and heated for 30 minutes; finally, the PDMS with the replicated structure is gently peeled off from the mold to obtain a PDMS sheet with a structure.

5. The method for preparing a nanofluidic memristor based on a nano-milling array nanochannel structure according to claim 1, characterized in that: In step 4, the prepared PDMS sheet is treated with an oxygen plasma cleaner at a power of 80 W for 30 seconds, the PDMS sheet with the microchannel array and the PDMS sheet with the nanochannel array are bonded according to the alignment mark, and then the bonded PDMS sheet is placed on a hot plate at 95° C. for 20 minutes.

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