Terahertz memristor radio frequency switch based on suspended nanoelectrode and preparation method thereof

Abstract

The invention discloses a suspended nanoelectrode-based terahertz memristor radio frequency switch on a high-resistance silicon wafer substrate and a preparation method thereof, and the switch comprises a substrate, the upper surface of the substrate is provided with a connecting layer, the upper surface of the connecting layer is provided with an inert electrode layer, the upper surface of the inert electrode layer is provided with a Nafion dielectric layer, and the upper surface of the Nafion dielectric layer is provided with an active electrode layer. An inert metal layer is arranged on the upper surface of the active electrode layer, and the radio frequency switch in the design takes a Nafion ion exchange membrane as a main material and comprises a silicon substrate layer, a chromium connecting layer, an inert bottom layer electrode, a Nafion thin film middle layer, an active top layer electrode and an inert metal protection layer which are sequentially arranged from bottom to top. Protruding microstructures are prepared on a silicon substrate layer through an etching process, inert electrodes are suspended, the whole memristor radio frequency switch is mainly formed by overlapping two electrodes and a middle layer, and non-volatility is shown by connecting an active electrode with a positive electrode, connecting the inert electrodes with a negative electrode and applying turn-on and turn-off voltages.

Description

Technical Field

[0001] The present invention belongs to the field of non-volatile electronic devices, and in particular relates to a terahertz memristive radio frequency switch based on suspended nanoelectrodes and a preparation method thereof. Background Art

[0002] An RF switch is a device used to control the transmission of RF signals and is commonly used in RF systems such as wireless communications, radar, and satellite communications. RF switches can control the on / off function of RF signals, thereby switching, connecting, or isolating them, and are a crucial component of RF systems.

[0003] Traditional RF switches use mechanical, solid-state, and electromagnetic operating principles. Mechanical RF switches typically switch signals on and off by connecting and disconnecting a mechanical structure. They offer high voltage and current resistance, but suffer from issues like short lifespan and slow response speed. Solid-state RF switches use solid-state devices (such as MOSFETs and PIN diodes) as switching elements. These offer advantages like fast response, long lifespan, and compact size, but they also consume high power and have poor voltage resistance. Electromagnetic RF switches utilize electromagnetic principles to switch signals on and off. They offer high voltage and current resistance, but are bulky and consume a lot of power.

[0004] Non-volatile devices, in contrast to volatile devices, are devices that can retain stored information even when power is off. They are commonly used in storage devices such as computer memory and solid-state drives, as well as specialized applications such as aerospace and military applications. Traditional non-volatile devices include flash memory and EEPROM (electrically erasable programmable read-only memory). These devices operate primarily based on dielectric, electrochemical, and magnetic principles, storing and retrieving information by changing the physical state of the material or the charge distribution. Summary of the Invention

[0005] To address these issues, the present invention discloses a terahertz memristive radio frequency switch based on suspended nanoelectrodes. This novel radio frequency switch, fabricated from a non-volatile device, offers reduced power consumption, rapid response, high isolation, and low insertion loss. A method for fabricating this non-volatile device is also provided, featuring excellent processability and high machining precision.

[0006] Technical Solution: The present invention's terahertz memristive RF switch based on suspended nanoelectrodes utilizes a high-resistance silicon wafer as a substrate. The device comprises, from bottom to top, a silicon substrate layer, a chromium connecting layer, an inert bottom electrode, a Nafion dielectric layer, an active top electrode, and an inert metal protective layer. A raised microstructure is created on the silicon substrate through an etching process, allowing the inert electrode to suspend. The entire non-volatile device primarily consists of two electrodes stacked on an intermediate layer. By connecting the active electrode to the positive pole and the inert electrode to the negative pole, and applying on and off voltages, the device exhibits non-volatility.

[0007] Furthermore, in the terahertz memristive RF switch based on suspended nanoelectrodes of the present invention, the positive electrode is an active electrode (such as metal copper) that is subjected to a forward voltage in the MIM structure; and the negative electrode is an inert electrode (such as metal gold) that is subjected to a reverse voltage in the MIM structure.

[0008] Furthermore, in the terahertz memristive radio frequency switch based on suspended nanoelectrodes of the present invention, the negative electrode metal covers the micro-convex structure, and the Nafion film covers the negative electrode metal and the micro-convex structure.

[0009] Furthermore, in the terahertz memristive radio frequency switch based on suspended nanoelectrodes of the present invention, the inert metal layer is used to prevent oxidation of the active metal of the positive electrode from affecting the device performance.

[0010] Furthermore, in the terahertz memristive radio frequency switch based on suspended nanoelectrodes of the present invention, the negative electrode metal layer and the inert metal layer must not overlap with the edge of the positive electrode metal layer to avoid short circuit.

[0011] The present invention utilizes optical lithography, spin coating, and electron beam evaporation to fabricate nonvolatile devices. Reasonable process steps, including the shape of the lithography template, are designed to obtain the desired silicon-based microstructure, thereby reducing insertion loss and improving isolation in the novel radio frequency switch.

[0012] The method of the present invention for preparing a terahertz memristive radio frequency switch based on suspended nanoelectrodes comprises the following steps: Step 1: Spin-coat photoresist on the surface of the silicon wafer, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer; Step 2: Using a dry etching process, the micro-convex structure pattern is etched into silicon to obtain silicon pillars of a predetermined size; Step 3: Use wet etching process and anisotropic etching to etch the silicon pillar into a pyramid; Step 4: Spin-coat photoresist on the surface of the silicon wafer, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer; Step 5: Use electron beam evaporation technology to evaporate the connection layer and inert electrode layer on the pattern, and finally remove the remaining photoresist and excess materials; Step 6: Spin-coat Nafion solution on the upper surface of the inert electrode layer to form a film through the process; Step 7: Spin-coat photoresist on the upper surface of the device, and then use optical lithography technology to define the required pattern on the upper layer of the spin-coated photoresist; Step 8: Etch away the photoresist and Nafion film outside the desired pattern by argon ion etching to prepare the Nafion dielectric layer; Step 9: Spin-coat photoresist on the device surface, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer; Step 10: Use electron beam evaporation technology to evaporate the active electrode layer and the inert metal layer on the pattern, and finally remove the residual photoresist and excess materials. The inert electrode layer must not overlap with the edges of the active electrode layer and the inert metal layer to avoid short circuit. The inert metal layer is to prevent the active metal layer from oxidizing and affecting the device performance.

[0013] Furthermore, in the method of the present invention, the positive electrode is a vapor-deposited active metal, such as Cu, Ag; and the negative electrode is a vapor-deposited inert metal, such as Au, Pt.

[0014] Considering that the terahertz memristive RF switch based on suspended nanoelectrodes has a small design size, is simple to prepare, and is easy to obtain strong cycling characteristics, the applicant uses advanced micro-nano processing technology to design and prepare this memristive RF switch.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following advantages: 1. The non-volatility of the memristive RF switch enables it to remain stable when switching states without continuous energy consumption, thus realizing low-power RF switching. It also has good electrochemical activity, which can achieve fast switching response speed, meeting the RF system's demand for high-speed signal switching. 2. Through the tip discharge effect, the direction of the potential barrier formation of the conductive filaments is precisely induced, making the generation theory of the conductive filaments controllable, significantly improving the stability of the switch switching, effectively overcoming the inherent defects of the switch based on this mechanism, and laying a solid foundation for the practical application of this type of switch.

[0016] 3. The nanoscale design of RF switches significantly improves their performance under high-frequency conditions, breaking through the technical bottleneck of traditional switches in the high-frequency field.

[0017] 4. While achieving nanoscale performance, the process utilizes processing accuracy requirements of tens of microns, enabling the process to have the ability to be mass-produced at low cost, providing technical support for the industrial application of RF switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1Side view of a terahertz memristive RF switch based on suspended nanoelectrodes. Figure 2 Top view of the terahertz memristive RF switch based on suspended nanoelectrodes; Figure 3 Process flow chart of terahertz memristive RF switch based on suspended nanoelectrodes; Figure 4 Suspended electrode example of a terahertz memristive RF switch based on suspended nanoelectrodes; Figure 5 Response time of a terahertz memristive radio frequency switch based on suspended nanoelectrodes.

[0019] List of reference numerals in the accompanying drawings: silicon substrate layer 1 , connection layer 2 , inert electrode layer 3 , Nafion layer 4 , active electrode layer 5 , inert metal protection layer 6 . DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0021] Example: This example is a terahertz memristive radio frequency switch based on suspended nanoelectrodes: Example 1: The terahertz memristive RF switch based on suspended nanoelectrodes of the present invention uses a high-resistance silicon-based wafer as a carrier and includes a silicon substrate layer 1, a connection layer 2, an inert electrode layer 3, a Nafion dielectric layer 4, an active electrode layer 5, and an inert metal protective layer 6, arranged from bottom to top. A raised microstructure is prepared on the silicon substrate layer through an etching process to achieve the suspension of the inert positive electrode. The entire non-volatile device is mainly composed of two electrodes and an intermediate layer. By connecting the active electrode to the positive electrode and the inert electrode to the negative electrode, the non-volatility is exhibited by applying the on and off voltages. The memristive RF switch is covered with the inert electrode of the high-resistance silicon-based wafer. The electrode thickness is 500nm, and the thickness of the active electrode arranged on the top is also 500nm.

[0022] The present invention uses a method for preparing a non-volatile device based on an MIM structure to prepare a terahertz memristive radio frequency switch based on suspended nanoelectrodes. Taking the inert electrode thickness of 500nm, the dielectric layer thickness of 500nm, and the active electrode thickness of 500nm as an example, the preparation process is as follows: Step 1: Spin-coat photoresist on the upper surface of the substrate layer 1 of the silicon-based wafer, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer, as shown in Figure 3 (a); Step 2: Using a dry etching process, the micro-convex structure pattern is etched into silicon to obtain silicon pillars of a predetermined size, as shown in Figure 3 (c); Step 3: Use wet etching process and anisotropic etching to etch the silicon pillar into a pyramid, as shown in Figure 3 (d); Step 4: Spin-coat photoresist on the surface of the silicon wafer, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer, as shown in Figure 3 (e); Step 5: Use electron beam evaporation technology to evaporate the connection layer 2 and the inert electrode layer 3 on the pattern, and finally remove the remaining photoresist and excess materials. The effect is shown in Figure 3 (g); Step 6: Spin-coat Nafion solution on the upper surface of the inert electrode layer 3 to form a film through the process, as shown in Figure 3 (h); Step 7: Spin-coat photoresist on the device surface, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer, as shown in Figure 3 (i); Step 8: The photoresist and Nafion film outside the desired pattern are etched away by argon ion etching to prepare the Nafion dielectric layer 4, as shown in FIG3 (k); Step 9: Spin-coat photoresist on the device surface, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer, as shown in Figure 3 (l); Step 10: Electron beam evaporation is used to deposit an active electrode layer 5 and an inert metal layer 6 on the pattern. Finally, the remaining photoresist and excess materials are removed. The effect is shown in FIG3 (n). The inert electrode layer 3 must not overlap with the edges of the active electrode layer 5 and the inert metal layer 6 to avoid short circuits. The inert metal layer 6 is to prevent oxidation of the active metal layer 5 and affect device performance. The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above-mentioned technical features.

[0023] Example 2: This invention utilizes a terahertz memristive RF switch based on suspended nanoelectrodes. Using a deep silicon anisotropic lithography process, conical silicon pillars, as shown in Figure 4, are fabricated on a silicon substrate. The tops of the pillars are nanometer-scale, thereby suspending the inert electrode layer. Actual testing, as shown in Figure 5, demonstrated an on-state response time of 45ns and an off-state response time of 120ns. Based on this data, the calculated on-state power consumption is approximately 0.174nJ, and the off-state power consumption is approximately 8.619nJ.

[0024] It should be noted that the above content merely illustrates the technical idea of ​​the present invention and cannot be used to limit the scope of protection of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications all fall within the scope of protection of the claims of the present invention.

Claims

1. A terahertz memristive radio frequency switch based on suspended nanoelectrodes, characterized in that: The invention comprises a substrate (1), wherein a connection layer (2) is arranged on the upper surface of the substrate (1), an inert electrode layer (3) is arranged on the upper surface of the connection layer (2), a Nafion dielectric layer (4) is arranged on the upper surface of the inert electrode layer (3), an active electrode layer (5) is arranged on the upper surface of the Nafion dielectric layer, and an inert metal layer (6) is arranged on the upper surface of the active electrode layer (5).

2. The terahertz memristive radio frequency switch based on suspended nanoelectrodes according to claim 1, characterized in that: The substrate silicon layer (1) is processed through an etching process to form a protruding microstructure.

3. The terahertz memristive radio frequency switch based on suspended nanoelectrodes according to claim 2, characterized in that: The inert electrode layer (3) covers the protruding microstructure portion in the substrate silicon layer (1).

4. The terahertz memristive radio frequency switch based on suspended nanoelectrodes according to claim 1, characterized in that: The inert electrode layer (3) must not overlap with the edges of the active electrode layer (5) and the inert metal layer (6).

5. The method for preparing a terahertz memristive radio frequency switch based on suspended nanoelectrodes according to any one of claims 1 to 4, characterized in that: The preparation of the memristor radio frequency switch comprises the following steps: The first step: Spin-coat photoresist on the surface of the silicon-based wafer, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer; Step 2: Using a dry etching process, the pattern of the raised microstructure is etched into silicon to obtain silicon pillars of a predetermined size; Step 3: Use wet etching process and anisotropic etching to etch the silicon column into a cone; Step 4: Spin-coat photoresist on the surface of the silicon-based wafer, and then use optical lithography technology to define the required pattern on the spin-coated photoresist layer; Step 5: using electron beam evaporation technology to evaporate the connection layer (2) and the inert electrode layer (3) on the pattern, and finally removing the residual photoresist and excess materials; Step 6: Spin-coat the Nafion solution on the upper surface of the inert electrode layer (3) to form a film through a process; Step 7: Spin-coat photoresist on the upper surface of the device, and then use optical lithography technology to define the required pattern on the upper layer of the spin-coated photoresist; Step 8: Etch away the photoresist and Nafion film outside the desired pattern by argon ion etching to prepare a Nafion dielectric layer (4); Step 9: Repeat step 7, spin-coat photoresist on the upper surface of the device, and then use optical lithography technology to define the required pattern on the upper layer of the spin-coated photoresist; Step 10: Using electron beam evaporation technology to evaporate the active electrode layer (5) and the inert metal layer (6) on the pattern, and finally remove the remaining photoresist and excess materials. The inert electrode layer (3) must not overlap with the edges of the active electrode layer (5) and the inert metal layer (6).

6. The method for preparing a terahertz memristive radio frequency switch based on suspended nanoelectrodes according to claim 5, characterized in that: The positive electrode is an active electrode deposited by evaporation, the negative electrode is an inert electrode deposited by evaporation, and the connecting layer is a metal with stronger adhesion.

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