Electronic tag based on memristor radio frequency switch and manufacturing method thereof

Abstract

The invention discloses an electronic tag based on a memristor radio frequency switch and a manufacturing method of the electronic tag, and mainly solves the problem that a traditional electronic tag is large in insertion loss, low in isolation degree and working frequency and poor in performance. Comprising a flexible substrate, an inductance coil, an RFID chip and a memristor radio frequency switch, the inductance coil, connected with the RFID chip, on the flexible substrate penetrates through the switch, and the switch comprises the flexible substrate, a metal adhesion layer, a bottom electrode and a top electrode; wherein the top electrode is in a step shape formed by an upper step and a lower step, and a resistive layer material is arranged below the top electrode; the upper step, the resistive layer material and the bottom electrode are distributed from top to bottom to form a memristor; and integration of the electronic tag and the switch is realized through a PSPI photoetching process, and manufacturing of the electronic tag is completed. The electronic tag manufactured by the invention has the characteristics of low insertion loss, high isolation, miniaturization, high response speed, high working frequency and high cut-off frequency, and the connectivity of flexible electronic equipment can be remarkably enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and further relates to electronic tag technology. Specifically, it is an electronic tag based on a memristor radio frequency switch and a manufacturing method thereof, which can be used in flexible and wearable electronic devices. Background Art

[0002] Since the first memristor was made by HP Labs in a milestone way in 2008, the field of memristors has developed rapidly. Researchers have made numerous memristors with excellent performance by changing the resistive switching layer materials with different electrical characteristics, such as phase change memristors, two-dimensional (2D) memristors, etc. These emerging devices have unique advantages such as non-volatility, variable resistibility, low power consumption, and high integration density, making them have revolutionary potential in various fields such as artificial intelligence, neuromorphic computing, non-volatile memory, signal processing, filtering, and radio frequency design. Therefore, in recent years, memristor-based designs have received great attention from researchers. In terms of manufacturing process, its scalability and compatibility with existing manufacturing processes have made it a hot topic in the industry, paving the way for faster and more efficient architecture design.

[0003] With the in-depth development of modern communication technology, communication devices are developing towards miniaturization, reconfigurability, and low power consumption. This requires each component in the communication device to adopt a miniaturized design, control the size and thickness of the device as much as possible, and at the same time minimize the number of components and the power consumption of the components. The new design of wireless devices with multiple frequency bands and standards requires the reuse of RF chains to minimize their size and power consumption. Due to the growing demand for multifunctional, lightweight, and portable devices, the demand for flexible and wearable electronic devices is growing rapidly. With the introduction of artificial intelligence (AI), flexible electronic devices now provide strong interactivity, promoting the realization of functions such as real-time health management, exercise guidance, and remote intervention. However, artificial intelligence poses high requirements for the connectivity applied to flexible electronic products, which requires more effective transmission and feedback mechanisms for big data processing. Although modern wearable devices can already use a wide range of frequencies, including Bluetooth, Wi-Fi, and LTE / 5G, the current technology is not sufficient to meet the needs of next-generation applications. The implementation of 6G communication requires working in the range below 7-24 GHz and frequencies above 100 GHz, which poses challenges to the connectivity of electronic devices and the requirements for supporting multiplexed workloads. Although 6G technology has made significant progress in rigid devices, applying it to flexible circuits is still challenging due to the difficulty of maintaining reliable performance under mechanical deformation.

[0004] At present, memristors have been proven to be high-performance radio frequency switches. Their advantages of high cut-off frequency, high operating frequency, and small size can meet the requirements of modern communication technologies. Their non-volatility enables low power consumption in radio frequency systems without the need for energy to maintain the conductive state. These characteristics make electronic tags based on memristors strong competitors for future 6G communication. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned existing technologies and propose an electronic tag based on a memristor radio frequency switch and its manufacturing method. By introducing a memristor radio frequency switch and utilizing its radio frequency performance, the preparation of high-performance electronic tags is realized, injecting new vitality into traditional electronic tags. The electronic tags prepared by the present invention have low insertion loss, high isolation, and high operating frequency, and can effectively enhance the connectivity of flexible electronic devices.

[0006] The technical solutions for achieving the purpose of the present invention are as follows:

[0007] An electronic tag based on a memristor radio frequency switch includes a flexible substrate 1, an inductance coil, and an RFID chip, and also includes a memristor radio frequency switch, wherein the inductance coil connecting the RFID chip on the flexible substrate passes through the switch;

[0008] The memristor radio frequency switch includes a flexible substrate 1, a metal adhesion layer 2, a bottom electrode 3, and a top electrode 5; wherein the top electrode 5 is a stepped type including a lower step 51 and an upper step 52; and a resistive switching layer material 4 is provided below the top electrode 5 to separate the top electrode 5 from the remaining material layers; the upper step 52, the resistive switching layer material 4, and the bottom electrode 3 are distributed from top to bottom to form a memristor;

[0009] Further, the above-mentioned lower step 51 is located at the upper part of the flexible substrate 1, and only the resistive switching layer material 4 is sandwiched between them; between the upper step 52 and the flexible substrate 1, from top to bottom, there are successively the resistive switching layer material 4, the bottom electrode 3, and the metal adhesion layer 2.

[0010] A manufacturing method of an electronic tag based on a memristor radio frequency switch includes the following steps:

[0011] S1) Clean the PI substrate with acetone and isopropyl alcohol, place it on the SiO2 substrate, and then spin-coat the polyimide PSPI material onto the PI substrate at a speed of 2900 to 3200 rpm / min; then place the PI substrate in a vacuum and bake it at a temperature of 180 °C for 2 hours to form the flexible substrate 1;

[0012] S2) Define the position of the memristor radio frequency switch by photolithography, and then deposit a 10 - 15 nm Ti layer as the adhesion layer 2 on the clean flexible substrate 1 by physical vapor deposition;

[0013] S3) Deposit 20 - 30 nm of Au as the bottom electrode 3 on the adhesion layer 2 by photolithography, electron beam evaporation and lift-off, and pattern it for the subsequent design of the ground-signal-ground (GSG) structure;

[0014] S4) Grow a multilayer hBN or MoS2 or WS2 resistive switching layer 4 on a Cu foil or sapphire or sapphire substrate by CVD process;

[0015] S5) Set corresponding conditions according to the material of the resistive switching layer 4, and transfer the grown resistive switching layer 4 to the patterned bottom electrode 3 by wet transfer;

[0016] S6) Deposit Au or Pt or Ag simultaneously above the resistive switching layer 4 by electron beam evaporation to form a stepped top electrode 5 in an integral shape composed of an upper step 52 with a thickness of 30 - 40 nm and a lower step 51 with a thickness of 20 - 30 nm;

[0017] S7) Use Ar plasma etching to remove the resistive switching layer material 4 that is not in contact with the upper step 52 part of the top electrode;

[0018] S8) Define the position of the inductor coil by photolithography, and deposit 50 nm of Nb by thermal evaporation to form the inductor coil;

[0019] S9) Define the position of the RFID chip by photolithography, connect the packaged RFID chip to the inductor coil, and complete the production of the electronic tag.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] First, since the present invention designs a memristor radio frequency switch and adds a resistive switching layer material between its top electrode and other material layers, compared with traditional radio frequency switches, using this memristor radio frequency switch to make an electronic tag can endow the tag with excellent performance of low insertion loss and high isolation, thereby making the electronic tag more miniaturized, with a faster response speed, and higher operating frequency and cut-off frequency.

[0022] Second, the present invention realizes the 2.5D integration of the electronic tag and the RF switch through the PSPI photolithography process, and the obtained tag has a simple structure, flexible design, and is easy for heterogeneous integration.

[0023] Third, the advanced packaging and excellent performance of the electronic tag fabricated by the present invention make it an ideal choice for 6G communication technology, and can provide important support for the future development of related technologies. Brief Description of the Drawings

[0024] Figure 1 is a schematic structural diagram of the electronic tag of the present invention;

[0025] Figure 2 It is a schematic diagram of the device structure of the memristor radio frequency switch in the electronic tag of the present invention;

[0026] Figure 3 It is a schematic diagram of the manufacturing process flow of the memristor radio frequency switch in the electronic tag of the present invention;

[0027] Figure 4 It is a schematic diagram of the manufacturing process flow of the electronic tag of the present invention. Specific Embodiments

[0028] The following further describes the present invention in detail with reference to the accompanying drawings and embodiments.

[0029] Embodiment 1: Referring to Figure 1 , an electronic tag based on a memristor radio frequency switch proposed by the present invention includes a flexible substrate 1, an inductance coil, and an RFID chip, and further includes a memristor radio frequency switch, wherein the inductance coil connecting the RFID chip on the flexible substrate passes through the switch;

[0030] Referring to Figure 2 , the memristor radio frequency switch includes a flexible substrate 1, a metal adhesion layer 2, a bottom electrode 3, and a top electrode 5; wherein the top electrode 5 is a stepped type including a lower step 51 and an upper step 52; and a resistive switching layer material 4 is provided below the top electrode 5 for separating the top electrode 5 from the remaining material layers; the upper step 52, the resistive switching layer material 4, and the bottom electrode 3 are distributed from top to bottom to form a memristor. The lower step 51 is located in the upper part of the flexible substrate 1, and only the resistive switching layer material 4 is sandwiched between them; between the upper step 52 and the flexible substrate 1, from top to bottom, there are successively the resistive switching layer material 4, the bottom electrode 3, and the metal adhesion layer 2.

[0031] In this embodiment, for the flexible substrate, it is preferably 100 - 200 μm in thickness; for the adhesion layer 2, it is preferably Ti with a thickness of 10 - 15 nm, located on the substrate 1; for the bottom electrode 3, it is preferably Au with a thickness of 30 - 40 nm, located on the adhesion layer 2; for the resistive switching layer 4, it is preferably hBN or MoS2 or WS2 with a thickness of 10 - 15 nm, located on the bottom electrode 4; for the top electrode 5, it is preferably Au or Pt or Ag, with a stepped shape, the upper step 52 has a thickness of 30 - 40 nm, and between it and the flexible substrate 1, there are successively the resistive switching layer 4, the bottom electrode 3, and the metal adhesion layer 2; the lower step 51 has a thickness of 20 - 30 nm, and between it and the flexible substrate 1 is the resistive switching layer 4.

[0032] Embodiment 2: Referring to Figure 3 and Figure 4 , a manufacturing method of an electronic tag based on a memristor radio frequency switch proposed by the present invention specifically includes the following steps:

[0033] Step S1) Clean the PI substrate with acetone and isopropyl alcohol, place it on the SiO2 substrate, and then spin-coat the polyimide PSPI material onto the PI substrate at a speed of 2900 to 3200 rpm / min; then place the PI substrate in a vacuum and bake it at a temperature of 180 °C for 2 hours to form the flexible substrate 1;

[0034] Step S2) Define the position of the memristor RF switch by photolithography, and then deposit a 10 - 15 nm Ti layer as the adhesion layer 2 on the clean flexible substrate 1 by physical vapor deposition;

[0035] Step S3) Deposit 20 - 30 nm of Au as the bottom electrode 3 on the adhesion layer 2 by photolithography, electron beam evaporation and lift-off and pattern it for the subsequent design of the ground-signal-ground GSG structure;

[0036] Step S4) Grow a multi-layer hBN or MoS2 or WS2 resistive switching layer 4 on a Cu foil or sapphire or sapphire substrate by CVD process; the process conditions are as follows:

[0037] For growing the hBN resistive switching layer, under the conditions that the argon flow rate is 200 - 250 sccm, the H2 flow rate is 50 - 80 sccm, the chamber pressure is stabilized at 350 - 450 Pa, and the raw material heating temperature is 102 - 105 °C, transfer the raw material decomposition product to the substrate surface to obtain the hBN thin film;

[0038] For growing the MoS2 resistive switching layer, set the argon flow rate to 40 - 60 sccm, stabilize the chamber pressure at 350 - 450 Pa, keep it in a stable state for 5 - 10 min and then heat it to 800 - 850 °C, and then directly cool it to room temperature;

[0039] For growing the WS2 resistive switching layer, set the argon flow rate to 100 - 120 sccm, stabilize the chamber pressure at 350 - 450 Pa, keep it in a stable state for 5 - 10 min and then heat it to 960 - 1000 °C, and then directly cool it to room temperature.

[0040] Step S5) Set the corresponding conditions according to the material of the resistive switching layer 4, and transfer the grown resistive switching layer 4 to the patterned bottom electrode 3 by wet transfer. In this embodiment, in this step, different conditions are specifically set for transfer according to different materials of the resistive switching layer, as follows:

[0041] For the transfer of the hBN resistive switching layer:

[0042] First, spin-coat the PMMA solution on the hBN-Cu sample and heat it at 100 - 110 °C for 3 - 5 minutes, and float the sample on the surface of a 0.1 - 0.2 g ml -1 FeCl3 solution for 5 - 6 hours to etch the Cu substrate;

[0043] Then deposit the PMMA-hBN sample on the surface of deionized water and float it for 1 - 1.5 hours for cleaning;

[0044] Then pick up the PMMA-hBN sample and transfer it onto the bottom electrode (3), and heat it at 60 - 70 °C for 5 - 7 minutes to evaporate the deionized water between hBN and the bottom electrode (3);

[0045] Finally, place the whole device in acetone with a concentration of ≥99% for 12 - 14 h to dissolve the PMMA layer tightly connected to the hBN thin film and complete the transfer;

[0046] For the transfer of the MoS2 resistive switching layer:

[0047] First, spin - coat the PS solution onto the MoS2 thin - film sample and bake it at 90 - 100 °C for 15 - 20 min;

[0048] Then place the sample in deionized water, and the PS / MoS2 layer is naturally peeled off from the sapphire substrate under the action of surface energy;

[0049] Next, pick up the PS / MoS2 sample, transfer it onto the bottom electrode (3), and bake it at 90 - 100 °C for 50 - 60 min, and take it out after cooling to room temperature;

[0050] Finally, start from the edge of the PS / MoS2 thin film and soak the entire sample surface with toluene to dissolve the PS layer tightly connected to the MoS2 thin film and complete the transfer;

[0051] For the transfer of the WS2 resistive switching layer, its transfer operation is the same as that of the MoS2 resistive switching layer.

[0052] In step S6), deposit Au or Pt or Ag simultaneously above the resistive switching layer 4 by electron beam evaporation to form a stepped - type top electrode 5 with an integral shape composed of two parts: an upper step 52 with a thickness of 30 - 40 nm and a lower step 51 with a thickness of 20 - 30 nm.

[0053] The process conditions of electron beam evaporation used in the foregoing steps in this embodiment are as follows: vacuum degree 2.0×10 -4 ~3.0×10 -4 Pa, electron gun acceleration voltage 7 - 9 KV, electron gun beam current 0.9 - 1.1 A, power parameter 16 - 21%, evaporation time 220 - 260 s.

[0054] Step S7) Use Ar plasma to etch away the resistive switching layer material 4 that is not in contact with the stepped portion 52 of the top electrode; set the process conditions as follows: the argon gas flow rate is 45 - 50 sccm, the forward power of the RF generator is 90 - 95 W, the power of the inductively coupled plasma (ICP) generator is 500 - 550 W, the chamber pressure is about 70 - 80 mTorr, the plate temperature is 25 - 30 °C, and it lasts for 210 - 240 seconds. This is used to ensure good electrical contact of the subsequent GSG tips.

[0055] Step S8) Define the position of the inductor coil through photolithography, and use thermal evaporation to deposit 50 nm of Nb to form the inductor coil and the pad; the process conditions are as follows: the vacuum degree is 2×10 -4 ~5×10 -4 Pa, the deposition rate is 1 nm / min, the annealing temperature is 600 °C, and the annealing time is 60 min.

[0056] Step S9) Define the position of the RFID chip through photolithography, connect the packaged RFID chip to the inductor coil, that is, press the packaged RFID chip onto the pad to connect with the inductor coil, and then perform plastic packaging on it to complete the production of the electronic tag.

[0057] Example 3: The overall implementation steps of the electronic tag manufacturing method proposed in this example are the same as those in Example 2. Now, a radio frequency switch device with a resistive switching layer material of multilayer hBN with a thickness of 15 nm, a bottom metal electrode of Au with a thickness of 30 nm, a top metal electrode of Au with an upper stepped portion thickness of 40 nm, and a lower stepped portion thickness of 20 nm is given, and the preparation process of the present invention is further described in detail:

[0058] Step 1: Prepare the flexible substrate 1.

[0059] 1.1) Clean the flexible polyimide (PI) substrate:

[0060] Immerse the PI substrate in a 75% acetone solution for 15 min to remove organic impurities, then immerse it in a 75% isopropyl alcohol solution for 10 min to remove the residual acetone, then rinse it with deionized water to remove the residual isopropyl alcohol, and finally use a nitrogen gun to dry the silicon wafer to ensure that there is no moisture residue on the silicon wafer surface;

[0061] 1.2) Place the cleaned PI substrate on the SiO2 substrate, and then spin - coat the polyimide (PSPI) material onto the PI substrate at a speed of 2900 to 3200 rpm / min.

[0062] 1.3) Place the PI substrate in a vacuum and bake it at a temperature of 180 °C for 2 hours to form the flexible substrate 1.

[0063] Step 2: Sputter the adhesion layer 2 on the surface of the flexible substrate 1 by physical vapor deposition (PVD) technology.

[0064] 2.1) Evacuate the sputtering chamber:

[0065] Close the door of the sputtering chamber and start the vacuum pump to pump out the gas in the sputtering chamber to reach the required vacuum degree. The background vacuum degree is 10 -6 Pa;

[0066] 2.2) Fill with sputtering gas and perform pre-sputtering:

[0067] When the sputtering chamber reaches the required vacuum degree, fill with argon (Ar) as the sputtering gas under the process conditions of a flow rate of 40 cm 3 / min, a temperature of 50 °C, a pressure of 60 Pa, and a radio frequency power of 60 W;

[0068] Before formal sputtering, perform 10 minutes of pre-sputtering to remove oxides and other impurities on the surface of the target;

[0069] 2.3) Deposit a 10-nm-thick Ti metal as the adhesion layer on the surface of the high-resistivity silicon substrate 1 under the process conditions of a sputtering voltage of 1 kV, a sputtering current of 100 mA, a target-substrate distance of 30 cm, and a sputtering rate of 2 nm / min;

[0070] 2.3) Put the sample after depositing the adhesion layer into an annealing furnace for annealing. Set the temperature in the furnace to 730 °C and perform rapid annealing for 30 s in an N2 atmosphere to eliminate stress and defects in the deposited layer and improve its density and adhesion.

[0071] Step 3: Perform patterning operations for GSG design on the adhesion layer 2 and deposit the bottom electrode 3.

[0072] 3.1) Perform photolithography on the surface of the adhesion layer 2, that is, first coat a layer of photoresist on the surface of the adhesion layer 2, and then perform alignment, exposure, development, and pattern detection in sequence to form the area for depositing the upper metal electrode;

[0073] 3.2) Through electron beam evaporation (E-Beam), deposit 30-nm-thick Au as the bottom metal electrode 3 on the area lithographed on the adhesion layer 2 under the process conditions of evacuating the working chamber to 2.5×10 -4 Pa, an electron gun acceleration voltage of 8 kV, an electron gun beam current of 1 A, and an evaporation time of 240 s. Then put the sample into the photoresist stripping solution to remove the photoresist;

[0074] 3.3) Immerse the silicon wafer after removing the photoresist completely in acetone solution for 12 hours and apply ultrasonic treatment. Subsequently, clean the surface of the silicon wafer with deionized water to remove the residual acetone solution. Finally, dry the surface of the silicon wafer with nitrogen gas.

[0075] Step 4: Prepare a multi-layer hBN as the resistive switching layer 4 by chemical vapor deposition (CVD).

[0076] 4.1) Select a high-quality metal Cu foil substrate:

[0077] After ultrasonic cleaning and electrochemical polishing of the metal Cu foil substrate, place the metal Cu foil substrate at the exact center of the CVD tube furnace, and introduce 250 sccm of Ar and 50 sccm of H2 to ensure that the Cu foil substrate will not be oxidized at high temperatures. Heat the CVD tube furnace to 1055 - 1070 °C at a rate of 15 °C / min and anneal for 8 h, then cool it naturally to room temperature and take it out. After the high-temperature annealing treatment, the flatness of the surface of the Cu foil substrate will be further improved;

[0078] 4.2) Stabilize the chamber pressure at 350 - 450 Pa, heat the borane ammonia complex precursor raw material to 102 - 105 °C using a rapid heating high-temperature tube furnace. Its decomposition products will be transferred to the surface of the Cu foil substrate along with Ar, and an h-BN thin film will be obtained through intermolecular collisions. Observe the number of layers of the h-BN thin film grown by CVD through TEM images, and control the number of layers to be 15 - 20 layers;

[0079] Step 5: Wet-transfer the prepared wafer-level multi-layer hBN resistive switching layer 4 onto the patterned bottom electrode 3.

[0080] 5.1) Spin-coat liquid PMMA on the grown hBN-Cu sample under the process conditions of spin-coating at 500 rpm for 6 seconds and 3500 rpm for 30 seconds;

[0081] 5.2) Heat the PMMA-hBN-Cu sample at 100 °C for 3 minutes to improve its stability;

[0082] 5.3) Float the PMMA-hBN-Cu sample on the surface of a 0.1 g / ml -1 FeCl3 solution for 5 hours to etch the Cu substrate;

[0083] 5.4) Transfer the PMA-hBN sample to the surface of a 2 wt% HCl solution and float for 1 - 2 minutes for cleaning; then deposit the PMMA-hBN sample on the surface of deionized water and float for 1 hour for further cleaning;

[0084] 5.5) Transfer the PMMA-hBN sample onto the patterned bottom electrode 4, and heat it at 60 °C for 5 minutes to evaporate the residual water between hBN and the bottom electrode 4. Subsequently, immerse the whole sample in acetone with a purity of ≥99% for 12 h to remove PMMA.

[0085] Step 6: Deposit the top electrode 5 on the resistive switching layer 4.

[0086] Through electron beam evaporation (E-Beam), under the process conditions that the vacuum in the chamber is pumped down to 2.5×10 -4 Pa, the acceleration voltage of the electron gun is 8 kV, the beam current of the electron gun is 1 A, and the evaporation time is 240 s, deposit 40 nm of Au as the upper step part on the lithographed area of the resistive switching layer 4, and deposit 20 nm of Au as the lower step part on the non-lithographed area of the resistive switching layer 4. These two parts serve as the top metal electrode 5;

[0087] Step 7: Etch away the hBN that does not overlap with the top electrode 5 from the bottom electrode 3 area.

[0088] Under the process conditions that the argon gas flow rate is 45 sccm, the forward power of the RF generator is 90 W, the power of the inductively coupled plasma (ICP) generator is 500 W, the chamber pressure is about 70 mTorr, and the plate temperature is 30 °C, continuously etch for 210 s from the bottom electrode 3 area to etch away the hBN that does not overlap with the top electrode 5, so as to ensure good electrical contact performance of the sample; the bottom electrode 3 and the resistive switching layer material 4 and the upper step 52 part of the top electrode distributed in sequence above it form a memristor as a radio frequency switch.

[0089] Step 8: Deposit 50 nm of Nb to form an inductor coil and pads.

[0090] On the flexible substrate 1, form the inductor coil and pad patterns through a lithography process. Place the substrate into a thermal evaporation coating machine, evacuate the air, heat the Nb target to evaporate it and deposit it on the substrate. Under the process conditions that the vacuum degree is lower than 5×10 -4 Pa and the deposition rate is 1 nm / min, form a 50 nm thick Nb thin film. Finally, anneal at a temperature of 600 °C for 60 minutes to improve the crystallinity and conductivity of the Nb thin film.

[0091] Step 9: Connect the packaged RFID chip to the inductor coil.

[0092] 9.1) Use a dispensing machine to apply 1 μm thick conductive adhesive on the pads, then use a chip mounter to accurately mount the RFID chip on the pads. Finally, use a hot press to perform thermocompression bonding on the chip and the pads under the process conditions that the temperature is 200 °C, the pressure is 5 MPa, and the working time is 60 s, so that the conductive adhesive is cured to form an electrical connection;

[0093] 9.2) Place the connected sample into the encapsulation mold, inject PVC material, and complete the injection molding process under the process conditions of a temperature of 200 °C, a pressure of 100 MPa, and a cooling time of 20 s;

[0094] 9.3) Finally, place the sample in an oven and complete the thermal curing process under the process conditions of a temperature of 130 °C and a heating time of 20 min to form a stable label structure, and finally complete the production of the electronic label.

[0095] Example 4: The overall implementation steps of the electronic label manufacturing method proposed in this example are the same as those in Example 2. Now, a radio frequency switch device with a resistive switching layer material of multilayer MoS2 with a thickness of 10 nm, a bottom metal electrode of Au with a thickness of 30 nm, a top metal electrode of Pt, an upper step part with a thickness of 40 nm, and a lower step part with a thickness of 20 nm is given, and the preparation process of the present invention is further described in detail:

[0096] Step 1: Prepare the flexible substrate 1.

[0097] The specific implementation of this step is the same as that of step 1 in Example 1.

[0098] Step 2: Sputter the adhesion layer 2 on the surface of the flexible substrate 1 by physical vapor deposition (PVD) technology.

[0099] The specific implementation of this step is the same as that of step 2 in Example 1.

[0100] Step 3: Perform patterning operations for GSG design on the adhesion layer 2 and deposit the bottom electrode 3.

[0101] Perform photolithography on the surface of the adhesion layer 2, that is, first coat a layer of photoresist on the surface of the adhesion layer 2, and then perform alignment, exposure, development, and pattern detection in sequence to form the area for depositing the upper metal electrode;

[0102] Set the working chamber to evacuate to 2.5×10 -4 Pa, the electron gun acceleration voltage is 8 Kv, the electron gun beam current is 1 A, and the evaporation time is 240 s. Deposit Pt with a thickness of 40 nm as the bottom metal electrode 3 on the area of the adhesion layer 2 lithographed by electron beam evaporation (E-Beam), and then place the sample in a photoresist stripping solution to remove the photoresist;

[0103] Completely immerse the silicon wafer after removing the photoresist in acetone solution for 12 hours and apply ultrasonic treatment, then use deionized water to clean the surface of the silicon wafer to remove the residual acetone solution, and then use nitrogen to dry the surface of the silicon wafer.

[0104] Step 4: Chemically vapor deposit (CVD) a multilayer MoS2 thin film as the resistive switching layer 4.

[0105] First, place a high-quality sapphire substrate into a beaker, pour acetone until the substrate is completely covered, place it in an ultrasonic cleaner for ultrasonic treatment for 20 minutes, then rinse it with deionized water 2 - 3 times, place it in immersible deionized water for ultrasonic treatment for 15 minutes, and then perform nitrogen drying;

[0106] Next, place the substrate, molybdenum trioxide, and sulfur powder into a CVD device that has been leak-tested. Among them, the molybdenum source is placed in the high-temperature zone of the tube furnace, and the sulfur powder is placed in the low-temperature zone. The substrate is placed in the deposition area at the end. Adjust the argon flowmeter to 50 sccm, and adjust the gas valve to make the chamber pressure stable at 400 Pa. After maintaining a stable state for 5 minutes, heat it up to 800 °C, and then cool it to room temperature to form a MoS2 multi-layer film layer, and control the number of layers to be between 12 and 18 layers by observing the TEM image;

[0107] Step Five: Wet-transfer the prepared wafer-level multi-layer MoS2 resistive switching layer 4 onto the bottom electrode 3.

[0108] First, weigh 2.7 g of polystyrene (PS) powder as the solute with an electronic analytical balance, measure 30 mL of toluene as the solvent with a measuring cylinder, and magnetically stir for 3 hours at 80 °C to obtain a clear and transparent PS solution;

[0109] Next, fix the prepared MoS2 thin film sample at the center position of the spin coater with double-sided tape. Set the parameters of the spin coater to 5000 r / min and the rotation time to 50 seconds. Press the start button. When the rotation speed reaches the maximum, drop a drop of the prepared PS mixed solution onto the sample to ensure the uniformity of the PS layer spin-coated on the sample. Remove the sample after the time ends;

[0110] Then, place the spin-coated sample in an electric heating box and bake it at 90 °C for 15 minutes to remove toluene and precipitate PS to form a film, while strengthening the interaction between the MoS2 thin film and the PS layer;

[0111] Next, place the sample in deionized water, gently poke the surface of the sample edge with a pointed tweezer to give an initial driving force to the peeling process. Then, utilize the different hydrophilicities of the sapphire substrate and the MoS2 thin film to let the PS / MoS2 layer naturally peel off from the sapphire substrate under the action of surface energy;

[0112] Then, transfer the PS / MoS2 sample to the patterned bottom electrode 4, blot the moisture with absorbent paper, and press the film layer as evenly as possible to flatten it and reduce the air bubbles between the PS / MoS2 film layers;

[0113] Place the thin film sample transferred to the device by peeling in an electrothermal oven and bake it at 90 °C for 60 minutes for the second time to strengthen the bonding force between the MoS2 thin film and the metal electrode 4, evaporate the residual moisture, and take it out after cooling to room temperature;

[0114] Wet the entire surface of the sample with toluene starting from the edge of the MoS2 thin film for the sample after the second baking to dissolve the PS layer closely connected to the MoS2 thin film. After the PS layer is completely dissolved by toluene and the toluene is completely volatilized, take out the sample to complete the transfer.

[0115] Step Six: Deposit the top electrode 5 on the resistive switching layer 4.

[0116] Set the working chamber to be evacuated to 2.5×10 -4 Pa, the electron gun acceleration voltage is 8 KV, the electron gun beam current is 1 A, and the evaporation time is 240 s. Under these process conditions, deposit 30 nm of Pt as the upper step part on the lithographed area of the resistive switching layer 4 through electron beam evaporation E-Beam, and deposit 20 nm of Pt as the lower step part on the non-lithographed area of the resistive switching layer 4. These two parts serve as the top metal electrode 5.

[0117] Step Seven: Etch away the MoS2 that does not overlap with the top electrode 5 from the bottom electrode 3 area.

[0118] Set the argon gas flow rate to 45 sccm, the forward power of the RF generator to 90 W, the power of the inductively coupled plasma ICP generator to 600 W, the chamber pressure to about 60 mTorr, and the plate temperature to 35 °C. Continuously etch for 220 seconds from the bottom electrode 4 area to etch away the MoS2 that does not overlap with the top electrode 5 to ensure good electrical contact performance of the sample;

[0119] The bottom electrode 3 and the resistive switching layer material 4 and the upper step 52 part of the top electrode distributed in sequence above it form a memristor as a radio frequency switch.

[0120] Step Eight: Deposit 50 nm of Nb to form an inductor coil.

[0121] The specific implementation of this step is the same as that of step 8 in Embodiment Three.

[0122] Step Nine: Connect the packaged RFID chip to the inductor coil.

[0123] The specific implementation of this step is the same as that of step 9 in Embodiment Three.

[0124] Example 5: The overall implementation steps of the electronic tag manufacturing method proposed in this example are the same as those in Example 2. Now, a radio frequency switch device with a multi-layer WS2 resistive switching layer having a thickness of 10 nm, a bottom metal electrode of Au with a thickness of 30 nm, a top metal electrode of Ag, an upper step part with a thickness of 40 nm, and a lower step part with a thickness of 30 nm is given, and the preparation process of the present invention is further described in detail:

[0125] Step A: Prepare the flexible substrate 1.

[0126] The specific implementation of this step is the same as Step 1 in Example 3.

[0127] Step B: Sputter the adhesion layer 2 on the surface of the flexible substrate 1 by physical vapor deposition (PVD) technology.

[0128] The specific implementation of this step is the same as Step 2 in Example 3.

[0129] Step C: Perform patterning operations for GSG design on the adhesion layer 2 and deposit the bottom electrode 3.

[0130] C1) Perform photolithography on the surface of the adhesion layer 2, that is, first coat a layer of photoresist on the surface of the adhesion layer 2, and then perform alignment, exposure, development, and pattern detection in sequence to form the area for depositing the upper metal electrode.

[0131] C2) Deposit Au with a thickness of 30 nm as the bottom metal electrode 3 on the area lithographed on the adhesion layer 2 by electron beam evaporation (E-Beam), and then put the sample into the photoresist stripping solution to remove the photoresist. The process conditions for this electron beam evaporation are: the working chamber is evacuated to 2.0×10 -4 Pa, the electron gun acceleration voltage is 7.5 KV, the electron gun beam current is 1 A, and the evaporation time is 200 s;

[0132] C3) Immerse the silicon wafer completely in acetone solution for 12 hours and apply ultrasonic treatment, then use deionized water to clean the surface of the silicon wafer to remove the residual acetone solution, and finally use nitrogen to dry the surface of the silicon wafer.

[0133] Step D: Chemically vapor deposit (CVD) multi-layer WS2 as the resistive switching layer 4.

[0134] D1) Put the sapphire substrate into a beaker, pour acetone until the substrate is completely covered, put it into an ultrasonic cleaner for ultrasonic treatment for 20 min, then rinse it with deionized water 2 - 3 times, put it into immersible deionized water for ultrasonic treatment for 15 min, and then perform nitrogen drying;

[0135] D2) Place the substrate, tungsten trioxide, and sulfur powder into the CVD apparatus that has been leak-tested. Among them, the tungsten source is placed in the high-temperature zone of the tube furnace, and the sulfur powder is placed in the low-temperature zone. The substrate is placed in the deposition area at the end. Then, adjust the argon flowmeter to 120 sccm, and stabilize the chamber pressure at 400 Pa by adjusting the gas valve. After maintaining a stable state for 5 minutes, heat up to 960 °C, and then cool to room temperature to generate a MoS2 multi-layer film layer. Control the number of layers to be between 12 and 18 layers by observing the TEM image;

[0136] Step E: Wet-transfer the prepared wafer-level multi-layer WS2 resistive switching layer 4 onto the bottom electrode 3.

[0137] The specific implementation of this step is the same as that of step five in Example Two.

[0138] Step F: Deposit the top electrode 5 on the resistive switching layer 4.

[0139] Through electron beam evaporation E-Beam, deposit 40 nm of Ag as the upper step part on the lithographed area of the resistive switching layer 4, and deposit 20 nm of Ag as the lower step part on the non-lithographed area of the resistive switching layer 4. These two parts serve as the top metal electrode 5, and then place the sample in the photoresist stripping solution to remove the photoresist;

[0140] The process conditions for this electron beam evaporation are set as follows: the vacuum degree of the working chamber is 2.5×10 -4 Pa, the acceleration voltage of the electron gun is 8 Kv, the beam current of the electron gun is 1 A, and the evaporation time is 240 s;

[0141] Step G: Etch away the WS2 that does not overlap with the top electrode 5 from the bottom electrode 3 area.

[0142] Use plasma etching to etch away WS2 from the bottom electrode 3 area to ensure good electrical contact performance of the sample. The bottom electrode 3 and the resistive switching layer material 4 and the upper step 52 part of the top electrode distributed in sequence above it form a memristor as a radio frequency switch. The process conditions for this plasma etching are set as follows: the argon gas flow rate is 65 sccm, the forward power of the RF generator is 90 W, the power of the inductively coupled plasma ICP generator is 650 W, the chamber pressure is about 60 mTorr, the plate temperature is 40 °C, and it lasts for 200 seconds.

[0143] Step H: Deposit 50 nm of Nb to form an inductance coil.

[0144] The specific implementation of this step is the same as that of step 8 in Example Three.

[0145] Step I: Connect the packaged RFID chip to the inductance coil.

[0146] The specific implementation of this step is the same as that of step 9 in Example Three.

[0147] In the preparation methods used in the above specific embodiments, unless otherwise specified, they are all conventional methods; the reagents and materials used, unless otherwise specified, can all be obtained commercially. The parts not detailed in the present invention belong to the common general knowledge of those skilled in the art.

[0148] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Obviously, for those skilled in the art, after understanding the content and principle of the present invention, various modifications and changes in form and details may be made without departing from the principle and results of the present invention. For example, in addition to using hBN, MoS2, WS2 as the resistive switching layer material, materials such as graphene can also be used as the resistive switching layer; in addition to using Au / Au, Pt / Au, Ag / Au for the upper and lower metal electrode layers, other metals matching the memristor can also be used. However, these corrections and changes based on the idea of the present invention are still within the protection scope of the claims of the present invention.

Claims

1. An electronic tag based on a memristor radio frequency switch, comprising a flexible substrate (1), an inductance coil, and an RFID chip, characterized in that: It further includes a memristor radio frequency switch, wherein the inductance coil connecting the RFID chip on the flexible substrate passes through the switch; The memristor radio frequency switch includes a flexible substrate (1), a metal adhesion layer (2), a bottom electrode (3) and a top electrode (5); wherein the top electrode (5) is a stepped type including a lower step (51) and an upper step (52); and a resistive switching layer material (4) is provided below the top electrode (5) to separate the top electrode (5) from the remaining material layers; The upper step (52), the resistive switching layer material (4) and the bottom electrode (3) are distributed from top to bottom to form a memristor.

2. The electronic tag according to claim 1, characterized in that: The lower step (51) is located at the upper part of the flexible substrate (1), and only the resistive switching layer material (4) is sandwiched between them; between the upper step (52) and the flexible substrate (1), from top to bottom, there are successively the resistive switching layer material (4), the bottom electrode (3) and the metal adhesion layer (2).

3. The electronic tag according to claim 1, wherein: The thickness of the flexible substrate (1) is 100 - 200 μm; the top electrode (5) is made of Au or Pt or Ag, wherein the thickness of the lower step (51) is 20 - 30 nm, and the thickness of the upper step (52) is 30 - 40 nm; the resistive switching layer (4) is made of hBN or MoS2 or WS2, and its thickness is 10 - 15 nm; the bottom electrode (3) is made of Au, and its thickness is 30 - 40 nm; the metal adhesion layer (2) is made of Ti, and its thickness is 10 - 15 nm.

4. A manufacturing method of the electronic tag according to claim 1, characterized in that It includes the following steps: S1) Clean the PI substrate with acetone and isopropyl alcohol, place it on the SiO2 substrate, and then spin - coat the polyimide PSPI material onto the PI substrate at a speed of 2900 to 3200 rpm / min; then place the PI substrate in a vacuum and bake it at a temperature of 180 °C for 2 hours to form the flexible substrate (1); S2) Define the position of the memristor radio frequency switch by photolithography, and then deposit a 10 - 15 nm Ti layer as the adhesion layer (2) on the cleaned flexible substrate (1) by physical vapor deposition; S3) Deposit 20 - 30 nm of Au as the bottom electrode (3) on the adhesion layer (2) by photolithography, electron beam evaporation and lift - off and pattern it for the subsequent design of the ground - signal - ground GSG structure; S4) Grow a multi - layer hBN or MoS2 or WS2 resistive switching layer (4) on a Cu foil or sapphire or sapphire substrate by CVD process; S5) Set corresponding conditions according to the material of the resistive switching layer (4), and transfer the grown resistive switching layer (4) to the patterned bottom electrode (3) by wet transfer; S6) Deposit Au or Pt or Ag simultaneously above the resistive switching layer (4) by electron beam evaporation to form a stepped - type top electrode (5) in an integral shape composed of two parts: an upper step (52) with a thickness of 30 - 40 nm and a lower step (51) with a thickness of 20 - 30 nm; S7) Use Ar plasma etching to remove the resistive switching layer material (4) that is not in contact with the upper step (52) part of the top electrode; S8) Define the position of the inductance coil by photolithography, and deposit 50 nm Nb by thermal evaporation to form the inductance coil; S9) Define the position of the RFID chip by lithography, connect the packaged RFID chip to the inductance coil, and complete the production of the electronic tag.

5. The method according to claim 4, characterized in that: For the physical vapor deposition used in step S2), the process conditions are as follows: The sputtering voltage is 0.9 - 1.1 KV, The sputtering current is 90 - 110 mA, The target-substrate distance is 25 - 35 cm, The sputtering rate is 2 - 4 nm / min.

6. The method according to claim 4, characterized in that: For the electron beam evaporation used in steps S3) and S6), the process conditions are as follows: The vacuum degree is 2.0×10 -4 ~3.0×10 -4 Pa, The accelerating voltage of the electron gun is 7 - 9 KV, The beam current of the electron gun is 0.9 - 1.1 A, The power parameter is 16 - 21%, The evaporation time is 220 - 260 s.

7. The method according to claim 4, characterized in that In step S4), grow a multi-layer hBN or MoS2 or WS2 resistive switching layer (4) by CVD process, and the process conditions are as follows: For growing the hBN resistive switching layer, under the conditions that the argon flow rate is 200 - 250 sccm, the H2 flow rate is 50 - 80 sccm, the chamber pressure is stable at 350 - 450 Pa, and the raw material heating temperature is 102 - 105 °C, transfer the raw material decomposition product to the substrate surface to obtain the hBN thin film; For growing the MoS2 resistive switching layer, set the argon flow rate to 40 - 60 sccm, stabilize the chamber pressure at 350 - 450 Pa, keep it in a stable state for 5 - 10 min and then heat it to 800 - 850 °C, and then directly cool it to room temperature; For growing the WS2 resistive switching layer, set the argon flow rate to 100 - 120 sccm, stabilize the chamber pressure at 350 - 450 Pa, keep it in a stable state for 5 - 10 min and then heat it to 960 - 1000 °C, and then directly cool it to room temperature.

8. The method according to claim 4, characterized in that: In step S7), use Ar plasma to etch away the resistive switching layer material (4) that is not in contact with the upper step (52) of the top electrode, and the process conditions are as follows: The argon flow rate is 45 - 50 sccm, The forward power of the RF generator is 90 - 95 W, The power of the inductively coupled plasma ICP generator is 500 - 550 W, The chamber pressure is about 70 - 80 mTorr, The plate temperature is 25 - 30 °C, Last for 210 - 240 seconds.

9. The method according to claim 4, characterized in that: In step S8), use thermal evaporation to deposit 50 nm Nb to form the inductance coil and the pad, and the process conditions are as follows: The vacuum degree is 2×10 -4 ~5×10 -4 Pa, The deposition rate is 1 nm / min, The annealing temperature is 600 °C, The annealing time is 60 min.

10. The method according to claim 4, wherein: In step S9), press the packaged RFID chip onto the pad and connect it to the inductance coil, and then perform plastic packaging, and the process conditions are as follows: The temperature of the thermocompression bonding process is 200 °C, The pressure is 5 MPa, The working time is 60 s; The temperature of the injection molding process is 200 °C, The pressure is 100 MPa, The cooling time is 20 s.

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