Anchor-point-free tilting type radio frequency micro-electro-mechanical switch based on structure super-lubricity, and driving and preparation method and system of anchor-point-free tilting type radio frequency micro-electro-mechanical switch

Abstract

The invention discloses an anchor-point-free tilting type radio frequency micro-electromechanical switch based on structure super-lubricity, and a driving and preparation method and system thereof. According to the scheme of the invention, a structure super-lubricity technology is innovatively introduced into a radio frequency micro-electromechanical switch design, and an anchor-point-free tilting type structure is constructed; by means of the near-zero-friction and zero-wear motion characteristics of the warped super-slip sheet on an atomic-scale smooth interface, the two core problems of contact wear adhesion and cantilever beam speed limitation of a traditional switch are fundamentally solved. Cooperative improvement of nanosecond-level high-speed switching, more than a hundred million times of cycle life, extremely low insertion loss lower than 0.2 dB and watt-level high-power transmission capacity is successfully achieved, meanwhile, the micro-nano manufacturing process is remarkably simplified through the full-plane structure, and a high-performance and high-reliability radio frequency front-end key device solution is provided for a 5G / 6G communication system.

Description

Technical Field

[0001] This invention belongs to the field of microelectromechanical systems (MEMS) technology, specifically relating to an anchor-free tilting radio frequency MEMS switch based on structural superslippery, its driving and fabrication method, and system. Background Technology

[0002] With the rapid development of 5G / 6G wireless communication technology, the performance requirements of electronic communication technology for radio frequency (RF) front-end devices are increasing, showing a significant trend towards high frequency, low loss, low power consumption, miniaturization, and high reliability. RF switches are the core components of the RF front-end in communication systems, undertaking the core functions of signal routing and channel switching. Their performance directly determines the signal quality and energy efficiency of the entire system.

[0003] Currently, mainstream RF switches such as PIN diodes and MOSFETs, taking the commercial product Qorvo TGS2313 as an example, experience a significant increase in insertion loss at high frequencies, making them unsuitable for the demands of future communication systems. Figure 1 As shown, with increasing signal frequency, the insertion loss rises from 0.7dB@6GHz to 1.45dB@20GHz, far exceeding the core requirement of low loss for future 6G systems. RF MEMS switches, with their advantages of extremely low power consumption, high isolation, low insertion loss, good linearity, and low cost, have become one of the mainstream development directions. However, traditional cantilever beam RF MEMS switches face core challenges, such as... Figure 2 As shown, the switching time is limited by the inherent mechanical resonant frequency of the cantilever beam structure, making it difficult to achieve nanosecond-level high-speed switching; and the mechanical contacts suffer from wear and sticking problems, resulting in limited switch life and reduced reliability; furthermore, the power is limited by the contact material and contact area, making it difficult to apply to high-power scenarios.

[0004] Although existing technologies have attempted to improve these problems by drilling holes in cantilever beams and optimizing materials, they often come at the expense of other aspects. For example, increasing speed may lead to a shorter lifespan or an increase in driving voltage, and the fundamental structural contradiction between friction, wear, and speed limitations has not yet been resolved.

[0005] Existing technology CN115789494A discloses a super-slippery component with edge warping and its manufacturing method, which achieves edge warping of the super-slippery plate through the balance of internal stress and van der Waals forces. However, this patent only provides a basic super-slippery component and does not cover its specific application in the field of radio frequency switches, nor does it provide any technical inspiration on how to integrate the warped super-slippery plate with the radio frequency electrode structure and the drive electrode structure to solve the specific technical problems of radio frequency switches.

[0006] Therefore, in view of the above-mentioned technical problems and defects, there is an urgent need to design and develop an anchor-free tilting radio frequency microelectromechanical switch based on structural super-slippery, as well as its driving and fabrication method and system. Summary of the Invention

[0007] To overcome the shortcomings and difficulties of the existing technology, the purpose of this invention is to provide an anchor-free tilting radio frequency microelectromechanical switch based on super-slippery structure, as well as its driving and manufacturing method and system; aiming to fundamentally solve the problems of contact wear and sticking, and to break through the limitation of cantilever beam on switching speed.

[0008] The first objective of this invention is to provide an anchor-free tilting radio frequency microelectromechanical switch based on a super-slippery structure; the second objective of this invention is to provide a method for driving the radio frequency microelectromechanical switch; the third objective of this invention is to provide a method for fabricating the radio frequency microelectromechanical switch; and the fourth objective of this invention is to provide a radio frequency front-end system.

[0009] The first objective of this invention is achieved as follows: an insulating substrate, and a driving electrode structure disposed on the insulating substrate; an insulating dielectric layer covering the driving electrode structure; the anchorless tilting radio frequency microelectromechanical switch further includes a radio frequency electrode structure disposed on the insulating dielectric layer, and at least one warped superslipper on the surface of the insulating dielectric layer, the middle section of the warped superslipper being adsorbed onto the surface of the insulating dielectric layer, and the two ends of the warped superslipper warping and respectively movably adhering to the radio frequency electrode structure; wherein, the radio frequency electrode structure includes at least one radio frequency signal electrode and a ground electrode, forming a coplanar waveguide structure; the warped superslipper, under the action of the electrostatic driving force applied by the driving electrode structure, warps relative to the insulating dielectric layer and controls the contact conduction or separation with the radio frequency signal electrode in real time to switch the conduction state of the radio frequency path; furthermore, the warped superslipper is adsorbed onto the surface of the insulating dielectric layer by van der Waals forces.

[0010] Furthermore, the driving electrode structure includes a first driving electrode and a second driving electrode, and a first ground electrode or a second ground electrode disposed therebetween.

[0011] The first driving electrode and the second driving electrode are arranged symmetrically, and the warped superslipper covers part of the first driving electrode, part of the first ground electrode and part of the second driving electrode in its natural state.

[0012] Furthermore, the number of the warped superslipper is two, each corresponding to a different radio frequency signal electrode;

[0013] When a voltage is applied to the first driving electrode and the third driving electrode, and the first ground electrode and the second ground electrode are grounded, the two warped superslippers warp up toward both ends of the device, separate from the radio frequency signal electrode, and the switch is in the off state.

[0014] When a voltage is applied to the second driving electrode and the first and second ground electrodes are grounded, the two warped superslippers tilt towards the center of the device, contacting the radio frequency signal electrode, and the switch is in the open state. Specifically, the switching response time of the switch is less than 500 nanoseconds.

[0015] Furthermore, the warped superslipper is a micron-scale sheet structure with a preset curvature; its curvature is formed by thermal stress mismatch of its own multilayer material; wherein, the cross-section of the warped superslipper is arc-shaped or approximately arc-shaped;

[0016] The material of the warped superslip sheet includes at least one of graphene, molybdenum disulfide, and boron nitride.

[0017] Furthermore, the warped superslipper has a square structure with a side length of 10–50 μm;

[0018] The long side dimension of the electrode in the driving electrode structure matches the side length of the warped superslipper, which is 10-50 μm, and the spacing between the electrodes is 1-10 μm;

[0019] The material of the warped super-slippery sheet is highly oriented pyrolytic graphite or multilayer graphene.

[0020] Furthermore, the radio frequency electrode structure is made of gold, with a thickness of 5nm to 30nm and an electrode resistance of less than 0.5 ohms; the surface roughness Ra of the contact surface between the radio frequency electrode structure and the warped superslipper is less than 0.8nm.

[0021] Furthermore, the insulating dielectric layer is made of silicon nitride, hafnium oxide, or silicon oxide; the thickness of the insulating dielectric layer is 50–300 nm.

[0022] The surface of the insulating dielectric layer in contact with the warped super-slippery sheet is chemically and mechanically polished to achieve an atomically smooth surface with a surface roughness of less than 2 nanometers, thereby forming a structural super-slippery interface.

[0023] The second objective of the present invention is achieved as follows: the method includes applying a first driving voltage to a first group of driving electrodes and grounding the corresponding grounding electrode, driving the warped superslipper to warp in a first direction, separating it from the radio frequency signal electrode, and the switch being in an off state;

[0024] A second driving voltage is applied to the second set of driving electrodes, and the corresponding grounding electrode is grounded, driving the warped superslipper to warp in a second direction opposite to the first direction, making contact with the radio frequency signal electrode, and the switch is in the on state.

[0025] Furthermore, the first driving voltage and / or the second driving voltage are optimized pulse voltage waveforms, the parameters of which include amplitude, pulse width, rise time and pulse interval. By adjusting these parameters, the warping speed, stability and impact of the warped superslipper are controlled in real time.

[0026] A third objective of the present invention is achieved as follows: the method includes fabricating a driving electrode structure on an insulating substrate; and depositing an insulating dielectric layer to cover the driving electrode structure and the substrate;

[0027] The surface of the insulating dielectric layer is subjected to chemical mechanical polishing to form an atomically smooth surface; wherein, during chemical mechanical polishing, the surface roughness of the insulating dielectric layer is controlled to be Ra<2nm;

[0028] A radio frequency electrode structure is fabricated on a polished insulating dielectric layer; and a pre-fabricated warped superslipper is transferred and fixed to a predetermined position on the insulating dielectric layer; wherein the warped superslipper is transferred and placed using microprobe transfer technology.

[0029] The fourth objective of the present invention is achieved as follows: the system integrates at least one of the aforementioned structurally super-slippery, anchor-free, tilting radio frequency microelectromechanical switches.

[0030] This invention utilizes the near-zero frictional warping motion of a warped superslipper on an atomically smooth interface to increase the switching response speed from microseconds to nanoseconds (up to 100-200 nanoseconds), breaking through the speed limitations of cantilever beam structures. By leveraging the zero-wear characteristics of the superslippery structure, the theoretical service life is extended to the level of hundreds of millions of cycles, eliminating contact wear and sticking problems. Through a parallel contact design with dual superslippers and the application of highly conductive materials, contact resistance is reduced, achieving excellent RF performance with insertion loss below 0.2dB@10GHz, while also improving power capacity. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram illustrating the relationship between signal frequency and insertion loss.

[0033] Figure 2 Schematic diagram of a cantilever RF MEMS switch;

[0034] Figure 3 This is a schematic diagram of the rocker switch driving principle of a rocker switch based on a structurally super-slippery, anchor-free rocker RF microelectromechanical switch according to the present invention; wherein, (a) is a schematic diagram of the cross-section of the rocker switch; (b) is a top view of the rocker switch;

[0035] Figure 4 The images are scanning electron microscope (SEM) images of the warped edge of the warped superslippery plate of the anchor-free warping radio frequency microelectromechanical switch based on structural superslippery according to the present invention; wherein, (a) is a schematic diagram of the morphology of the warped edge of the warped superslippery plate; and (b) is a schematic diagram of the height dimension of the warped edge of the superslippery plate.

[0036] Figure 5 This is a schematic diagram of a rocker switch driving structure for an anchorless rocker RF microelectromechanical switch based on a super-slippery structure according to the present invention; wherein, (a) is a schematic diagram of the off-state driving; and (b) is a schematic diagram of the on-state driving.

[0037] Figure 6 This is a schematic diagram of the alternating pulse voltage drive waveform parameters (V1 and V2 drive alternately) of an anchorless tilting radio frequency microelectromechanical switch based on structural superslippery.

[0038] Figure 7 This is a schematic diagram of the structure (switch drive test principle) of a Polytech Doppler three-dimensional vibration test platform for an anchorless tilting radio frequency microelectromechanical switch based on structural superslippery.

[0039] Figure 8 This is a schematic diagram of SEM test images of a warped superslipper based on a structurally superslippery, anchor-free, warped RF microelectromechanical switch according to the present invention; wherein, (a) is an overall schematic diagram of the warped superslipper; and (b) is a schematic diagram of the warped height of a local part of the warped superslipper.

[0040] Figure 9 This is a schematic diagram of the key process steps in the micro / nano fabrication of a warped super-slippery radio frequency microelectromechanical switch based on structural super-slippery structure, according to the present invention.

[0041] Figure 10 This is a schematic diagram of the driving method for an anchor-free tilting radio frequency microelectromechanical switch based on structural superslippery structure according to the present invention.

[0042] Figure 11 This is a schematic diagram of the fabrication process of an anchor-free tilting radio frequency microelectromechanical switch based on structural superslippery structure according to the present invention.

[0043] Figure 12This is a side view of an embodiment of the present invention, a non-anchored tilting radio frequency microelectromechanical switch based on structural superslippery.

[0044] Figure 13 This is a cross-sectional view of an embodiment of the present invention of an anchor-free tilting radio frequency microelectromechanical switch based on structural superslippery.

[0045] Figure 14 This is a schematic diagram of the fabrication process of an embodiment of the present invention, which is a non-anchored tilting radio frequency microelectromechanical switch based on structural superslippery.

[0046] Figure 15 This is a schematic diagram of the fabrication process steps for an embodiment of the present invention, which is a non-anchored tilting radio frequency microelectromechanical switch based on structural superslippery.

[0047] Figure 16 This is a schematic diagram illustrating the speed and voltage changes of an embodiment of an anchor-free tilting radio frequency microelectromechanical switch based on structural superslippery structure according to the present invention.

[0048] Figure 17 This is a schematic diagram of an embodiment of the present invention of an anchor-free tilting radio frequency microelectromechanical switch based on structural superslippery.

[0049] In the figure, 140-driving electrode; 141-first driving electrode; 143-second driving electrode; 145-third driving electrode; 142-first ground electrode; 144-second ground electrode; 110-warped superslipper; 111-first warped superslipper; 112-second warped superslipper; 151-insulating substrate; 131-insulating dielectric layer; 122-one end of the radio frequency signal electrode; 124-the other end of the radio frequency signal electrode; 120-radio frequency signal electrode; 121-first radio frequency signal electrode; 122-second radio frequency signal electrode; 123-third radio frequency signal electrode; 124-fourth radio frequency signal electrode; 160-measuring laser. Detailed Implementation

[0050] To enable those skilled in the art to better understand the purpose, technical solution, and advantages of this application, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] Many specific details are set forth in the following description in order to provide a full understanding of the invention. Those skilled in the art can easily understand other advantages and effects of the invention from the content disclosed in this specification. However, the invention may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0052] As described in the background section, traditional processing methods have drawbacks such as crosstalk in high-current electromechanical coupling measurements, blind spots in interface evolution observation, and insufficient structural integration. Furthermore, with the existing technology, it is difficult to stably apply high currents in friction testing.

[0053] In view of this, such as Figures 3-17 As shown, in a specific embodiment of this invention, an anchor-free warping RF MEMS switch is taken as the research object, focusing on the lifespan problems caused by contact wear and sticking, cantilever beam creep, and the limitations of switching speed (microsecond level) and power throughput due to the natural frequency of the cantilever beam in current RF MEMS switches. The most mainstream electrostatic drive method is adopted (with advantages such as low power consumption, high speed, low process complexity, high integration, and no high-frequency interference). Simultaneously, it innovatively combines structural super-slippery technology—characterized by near-zero friction, zero wear, and excellent electrical contact—to design an anchor-free warping structure, abandoning traditional cantilever beams and other suspended structures, thus reducing process complexity. The micron-level warping super-slippery plate can be adsorbed onto the moving interface by van der Waals forces, ensuring that it neither displaces nor experiences near-zero friction or wear under electrostatic constraint. This can simultaneously reduce switching time and excitation voltage, while improving switch lifespan and power throughput.

[0054] Design of anchorless rocker switch structure: A super-slip rocker switch structure is designed, such as... Figure 3 As shown, a warped superslipper is driven by a buried layer driving electrode, and a coplanar waveguide (CPW) line is designed. Specifically, an embodiment of the present invention provides an anchorless warped radio frequency microelectromechanical switch, including a driving electrode portion and a radio frequency electrode portion. The driving electrode is located on an insulating substrate 151, the insulating dielectric layer 131 is located on the driving electrode, the radio frequency electrode is located on the insulating dielectric layer, and the warped superslipper is located on the radio frequency electrode and the insulating dielectric layer. The first warped superslipper 111 and the second warped superslipper 112 are both warped superslippers. The first radio frequency signal electrode 121, the second radio frequency signal electrode 122, and the third radio frequency signal electrode 123 are radio frequency electrodes, forming a coplanar waveguide (CPW) structure. The first radio frequency signal electrode 121 and the third radio frequency signal electrode 123 are ground lines, and the second radio frequency signal electrode 122 is a radio frequency signal line.

[0055] A static theoretical model was established to investigate the influence of driving structural parameters (driving electrode size, warp superslipper size, and dielectric layer thickness, etc.) on performance parameters such as driving force and driving voltage. The design principles and criteria of the warp-type RF MEMS switch were extracted, including how to enhance the driving force without breakdown, how to reduce the driving voltage, how to increase the driving stroke, and how to achieve stable on / off switching, laying a theoretical foundation for the design of subsequent RF MEMS switching devices.

[0056] Based on static simulation, a prototype device was fabricated, and a warped superslipper was transferred and driven. Key dynamic performance parameters, such as driving speed, response time, and stroke, were analyzed. A dynamic model of the device was constructed based on the high-speed switching process of the warped RF MEMS switch. The mechanical behavior during the warping contact process was systematically analyzed, and the model was improved using experimental data. Methods to improve dynamic performance parameters were analyzed, and the impact of mechanical behavior on electrical contact and RF performance was further explored. Device parameters were optimized based on simulation data and experiments, and the device design was adjusted to achieve a lower driving voltage and faster driving response speed. The focus was on improving various performance indicators of the warped superslipper, such as… Figure 4 (a) shows the warped shape of the edge of the warped superslipper, as... Figure 4 As shown in (b), the edge warp height, contact interface resistance, etc., can be changed by altering the size of the superslipper to meet the switching requirements of the RF switch dynamics.

[0057] Micro / Nano Fabrication Processes and RF Performance Optimization: Improving micro / nano fabrication processes and adjusting design layouts, with a focus on improving the flatness of the warped superslipper contact interface, the flatness of the RF electrodes and their contact resistance, and adjusting the chemical mechanical polishing (CMP) process to ensure the warped superslipper can both adhere to the moving interface and move rapidly. Through electrical experiments and simulation analysis, the study investigates the device's motion stability and RF performance changes after multiple switching operations, examining various factors affecting reliability and RF characteristics during high-speed switching to support subsequent optimization schemes. Combining device fabrication processes, the contact interface is optimized to fabricate contact points with high reliability and low contact resistance, and the impact of material selection and structural optimization on switching performance is investigated. This achieves optimization and improvement of RF switch performance indicators (e.g., throughput, isolation, insertion loss).

[0058] Dynamic Control and Robust Drive Structure Design of Warped Superslipper: Future RF MEMS will place higher demands on switching speed (ns level) and lifespan (hundreds of millions of cycles). This solution proposes a new mechanical drive structure, in which the warped superslipper warps rapidly under uniform electrostatic load. The stability and wear durability after repeated warping are key issues that urgently need to be addressed. In addition, it is necessary to study how the layout and structural parameters of the drive system (drive / RF electrode layout, shape, size, insulation layer thickness, etc.) affect the dynamic characteristics of the superslipper RF switch; explore how voltage waveform and waveform parameters affect the dynamic characteristics of the superslipper switch (response time, switching speed, stable motion, etc.), and how to design and optimize waveform parameters to meet the requirements of speed and robustness.

[0059] Preferably, the overall device drive structure parameters depend on the size of the warped superslipper. Too large or too small a size of the warped superslipper will affect its warp height, which in turn affects the isolation of the switching device when it is in the off state. Preferably, the warped superslipper is generally square to ensure that the stress on each edge of the warped surface is as uniform as possible, with a side length of 10–50 μm. Preferably, the long side dimensions of all matching drive electrodes are consistent with the side length of the warped superslipper, also 10–50 μm, and the spacing between the electrodes is 1–10 μm. The projected area of ​​two warped superslippers is equivalent to the projected area of ​​all electrodes. The preferred RF electrode material is gold, with a thickness of 5 nm–30 nm and an electrode resistance of less than 0.5 ohms.

[0060] The lower the thickness of the insulating dielectric layer 131, the lower the voltage required to drive the warped superslipper, but the risk of voltage breakdown increases. The preferred materials for the insulating dielectric layer 131 are silicon nitride, hafnium oxide, and silicon oxide, with a thickness of 50–300 nm. The insulating substrate 151 is preferably a silicon oxide wafer or a conventional silicon wafer with a layer of insulating material deposited on it (such as silicon nitride, hafnium oxide, silicon oxide, etc.).

[0061] The warped superslipper process is based on patent CN115789494A. The material of the warped superslipper is highly oriented pyrolytic graphite, which is a very pure and highly ordered synthetic graphite material with excellent in-plane current conduction performance and a resistivity of 40-100μΩ·cm, which is superior to the resistivity of most metals. In addition, the surface is smooth and has a large contact area with the RF electrode, which can reduce contact resistance, improve linearity and reduce insertion loss.

[0062] Preferably, a warped superslip sheet with a specific warp height is prepared by growing multilayer graphene by CVD on an independent substrate, depositing a stress metal layer, and then annealing.

[0063] Low-impedance transmission stability and RF characteristic modulation of dynamic superslippery interfaces: The warped superslipper is the core component of the RFMEMS switch in this scheme. To achieve low-friction, wear-free, and high-reliability electrical contact performance, the key scientific problem to be solved is how to design the material and structure of the warped contact point to stabilize the contact area and contact resistance of the warped superslipper and the contact point. Furthermore, it is possible to establish a quantitative relationship between the mechanical behavior and RF characteristics (such as isolation and insertion loss) during the warping contact process, including how interface pressure, interface area, interface voltage, and electrical signal frequency affect the impedance of the superslippery interface, maximum current density, and RF characteristics such as the linearity, isolation, and insertion loss of the superslippery interface.

[0064] This project proposes a novel super-slippery interface warping MEMS actuation method, establishes a static theoretical model and a finite element simulation model of the actuation structure, clarifies the influence of actuation design on actuation performance, and explores the actuation structure with nanosecond-level response and low-voltage excitation waveform parameters. A micro-nano integrated fabrication process for super-slippery RF MEMS switches is developed. This includes the adjustment process for the warped super-slippery plate morphology, the surface preparation process for an atomically rough insulating layer with buried electrodes, and the overall integration manufacturing process, resulting in the fabrication of a prototype. Methods for testing the dynamic and RF characteristics of the super-slippery interface are mastered. This includes testing its dynamic displacement response, pull-in robustness, response time, driving voltage, and other dynamic indicators, as well as its RF performance such as linearity, isolation, and insertion loss, to verify the feasibility and effectiveness of the above design and fabrication mechanism.

[0065] First, regarding the design of a rocker switch structure, such as Figure 12 As shown, when voltage is applied to the first driving electrode 141 and the third driving electrode 145, and the first ground electrode 142 and the second ground electrode 144 are in a grounded state, the warped superslipper tilts towards both ends of the device and does not contact the second RF signal electrode 122 and the fourth RF signal electrode 124 of the signal line. The signal line is not connected, and the switching device is in the off state. When voltage is applied to the second driving electrode 143, and the first ground electrode 142 and the second ground electrode 144 are in a grounded state, the warped superslipper tilts towards the middle of the device and contacts the second RF signal electrode 122 and the fourth RF signal electrode 124 of the signal line. The signal line is connected, the RF signal can be conducted, and the switching device is in the off state. The linkage of the two warped superslippers and their parallel connection with the signal line can reduce the contact resistance of the signal line connection, thereby reducing insertion loss and improving linearity.

[0066] In specific embodiments of the present invention, such as Figure 5 As shown in (a), when a driving voltage V1 is applied to the third driving electrode and the second grounding electrode, the right side of the warped superslipper will be subjected to a vertical electrostatic force, thereby driving the warped superslipper to warp to the right and disconnect it from the RF electrode (off state). Similarly, as Figure 5(b) shows that when a driving voltage V2 is applied to the second driving electrode and the second grounding electrode, the left side of the warped superslipper will be subjected to a vertical electrostatic force, thereby driving the warped superslipper to warp to the left and contact the radio frequency electrode (on state). By controlling the waveform and phase of the excitation voltage, the driving control of the warped superslipper can be realized.

[0067] For the static and finite element model of the tilting switch drive, this scheme uses COMSOL multiphysics finite element software to establish a finite element simulation model of the super-smooth interface drive system. Static finite element simulation analysis is performed to analyze the influence of structural dimensional parameters on performance parameters such as driving voltage, interface electrode capacitance, horizontal electrostatic driving force, and normal electrostatic force. Specifically, the various parameters affecting each performance parameter obtained from the theoretical model analysis are equivalently applied to the constructed finite element model. The feasibility and effectiveness of the theoretical physical model are verified through finite element simulation analysis.

[0068] Furthermore, the structural parameters of the rocker switch were optimized. Based on the established structural super-slippery interface driving theoretical model, the influence of various structural parameters (electrode gap, electrode size, dielectric constant and thickness of insulating layer, super-slippery plate size, etc.) on performance parameters such as normal electrostatic pressure, driving voltage, and driving speed was initially explored. Then, combined with the finite element simulation results, the model results were repeatedly iterated and optimized to verify and improve them, and the control methods of relevant performance parameters were mastered.

[0069] This study investigates the dynamics of switching and the improvement of warped superslippery materials, focusing on a stable control method for the displacement of warped superslippery plates. Firstly, a two-dimensional lumped parameter model of the system dynamics is established. Preliminary analysis is then conducted on the influence of various parameters of the dual-voltage waveform and dimensional deviations in the manufacturing process on the system's pull-in dynamics characteristics. Figure 6 As shown, V1 and V2 alternately drive the switch to switch on / off states. Key parameters such as excitation amplitude, excitation time, pulse interval, and rise time will affect the switching speed, stability, durability, and other key performance characteristics of the switch. A three-dimensional finite element model is used to accurately extract suitable dual-voltage waveform parameters that meet the requirements of precise and stable control (minimal overshoot).

[0070] For the measurement and adjustment of the rapid and stable displacement of a warped superslipper, this scheme proposes to utilize a Polytech Doppler three-dimensional vibration testing platform (time resolution <100ns, displacement resolution <1nm), combined with electrical equipment such as an oscilloscope, signal generator, and probe station, to test the dynamic displacement, velocity, and switching time of the warped superslipper under a given driving waveform. Figure 7The diagram shows the physical image and schematic of the Polytech test platform (the movement of the superslipper causes a change in laser frequency). The performance of the actual driven superslipper is evaluated based on measured parameters such as the attraction speed and response time. The differences between simulation results and measured data are compared, and the causes are analyzed from aspects such as theoretical model deviations and dimensional fluctuations introduced during the integrated manufacturing process. Finally, stable and precise drive control of the structural superslipper is achieved.

[0071] Improved dimensional processing of warped super-slip sheets: Warped super-slip sheets are produced by depositing multiple layers of metal on a super-slip sheet. Due to the difference in thermal expansion coefficients, the deposited metal cap will generate in-plane stress after annealing, thus obtaining a warped super-slip sheet. Figure 8 As shown, the warp shape and height of the warp superslipper are illustrated. By changing the thickness variation of the multilayer metal and the material selection, the warp height of the warp superslipper can be effectively controlled, increasing the yield. Simultaneously, based on previous simulation and experimental results, the theoretical model was revised, the process improved, and the size of the warp superslipper was adjusted to reduce the contact resistance with the RF electrode, thereby obtaining a suitable warp height to achieve a balance between switching speed and switching isolation.

[0072] The micro / nano fabrication process and RF performance optimization involve several steps. First, an insulating layer is deposited on high-resistivity silicon. Next, driving electrode layers are fabricated, followed by the deposition of a 1μm thick silicon nitride insulating layer (ensuring sufficient allowance for polishing). Then, chemical mechanical polishing (CMP) is used to control the silicon nitride thickness on the driving electrode layer to approximately 100nm. RF electrodes are then deposited at specific locations, ensuring a smooth surface. Finally, using a tungsten probe and a nano-micromechanical control hand, a warped superslippery plate is transferred to an atomically rough silicon nitride surface at a specific location, forming a superslippery contact surface. Further research into these key processes requires experimental optimization and effective integration of various process parameters, steps, and material selection to complete the overall integrated fabrication of the prototype.

[0073] A CMP-based process for fabricating an insulating layer with buried electrodes and atomically roughened surfaces requires an atomically roughened surface (<1-2 nm) to create a superslippery contact between the warped superslipper and the insulating layer. The driving structure with buried electrodes means the deposited insulating layer replicates the substrate morphology, thus influencing the movement of the warped superslipper. For example... Figure 9 The diagram illustrates the micro / nano fabrication process steps for a warped superslippery RF switch, sequentially including: deposition of an insulating layer, deposition of a driving electrode, deposition of silicon nitride, CMP planarization, deposition of an RF electrode, and transfer of the warped superslippery sheet. Step 3 illustrates the surface unevenness of the insulating layer with buried electrodes. This approach utilizes CMP technology to achieve atomic-level roughness polishing of the silicon nitride insulating layer through repeated research and adjustment of process parameters and steps, including polishing allowance (>1μm), polishing speed, fixture front pressure, polishing slurry ratio, and polishing slurry composition.

[0074] A method for testing the radio frequency (RF) characteristics of a warp superslippery switch was developed. An RF test platform was built using equipment such as a network analyzer, probe station, signal generator, and voltage amplifier. Performance parameters such as isolation, insertion loss, return loss, linearity, VSWR, and thermal operating life were tested. The RF characteristic test results were compared with previous theoretical and simulation results to verify the effectiveness and correctness of the model, analyze the sources of error, and further improve and optimize the theoretical model and fabrication process. Finally, a laboratory prototype meeting the predetermined RF and dynamic characteristic requirements was fabricated.

[0075] Based on the characteristics of warped superslippery contacts—no wear, extremely low friction, and excellent electrical contact performance—this solution develops a high-speed, high-power, and long-life anchor-free superslippery RF MEMS contact switch.

[0076] Furthermore, this solution proposes a novel anchor-free RF MEMS contact switch design with switching speeds reaching the nanosecond level. The anchor-free design avoids the cantilever beam structure of traditional MEMS switches, thus avoiding the limitations imposed by the inherent resonant frequency of the cantilever beam on switching speed and lifespan. Switching speeds can exceed 500 nanoseconds, representing an improvement of 1-2 orders of magnitude. This novel switch uses a warped superslipper as the moving part, avoiding suspended structures, optimizing process complexity, and reducing the precision requirements for photolithography overlay, which helps improve device yield. Using an appropriate driving voltage significantly avoids pull-in shocks and sliding damage, thus enabling this novel switch to achieve a longer lifespan and providing a completely new design concept for RF MEMS switches.

[0077] By utilizing structurally superlubricated materials as contact points for RF MEMS switches, high reliability and high power transmission are achieved. The micron-scale structurally superlubricated interface possesses near-zero friction, wear-free operation, 100% full contact area, extremely small mass, high temperature resistance, and self-cleaning properties. We utilize warped superlubricated materials as contacts to form superlubricated contact interfaces such as superlubricated plates / Au metals, which significantly improves the reliability and power throughput of the contact points. This greatly expands the application scenarios of RF MEMS switches, enabling their use in high-power applications such as radar and base stations.

[0078] For the overall micro / nano integration fabrication of warped superslippers, this paper proposes an in-situ integration fabrication process for warped superslippers and driving electrodes based on the microprobe transfer method, taking into account the characteristics of warped superslippers and organically integrating traditional micro / nano fabrication techniques. Compared with traditional MEMS switches that lack floating structures, this process reduces fabrication difficulty and cost, facilitating cost reduction and large-scale application. Furthermore, this solution fully considers compatibility issues in the aforementioned integration process and how to integrate and optimize the process accordingly.

[0079] In other words, the design of the anchorless RF MEMS contact switch in this scheme is an innovative attempt to apply the super-lubricating structure technology in the field of MEMS devices. It provides a new technical route for the integration of components in similar MEMS devices and will greatly enhance the application value and potential of RF MEMS switches.

[0080] Building upon the above embodiments, this embodiment demonstrates a structurally super-slippery radio frequency switch using high-resistivity silicon as the insulating substrate. On the substrate, a gold-based driving electrode structure is fabricated using photolithography, electron beam evaporation, and lift-off processes. Specifically, the structure includes a first driving electrode, a second driving electrode, and a common ground electrode located between the two.

[0081] Subsequently, a silicon nitride layer with a thickness of approximately 1.1 μm was deposited on the entire structure using plasma-enhanced chemical vapor deposition to form an insulating dielectric layer. The surface of this silicon nitride layer was then polished using chemical mechanical polishing (CMP). By controlling the composition of the polishing slurry (such as silica gel), the polishing pressure, and the rotation speed, the surface roughness Ra was reduced to below 0.8 nm, resulting in an atomically smooth surface.

[0082] Subsequently, two gold radio frequency (RF) signal electrodes, each approximately 500 nm thick, were fabricated on the polished insulating dielectric layer using photolithography and electroplating processes. In the areas where contact with the warped superslipper is required, the surfaces of the RF signal electrodes themselves constitute a metallization layer.

[0083] The core moving component of this invention is a prefabricated warped superslip sheet. This superslip sheet has a multilayer graphene structure and a size of approximately 20 μm × 20 μm. A layer of tensile-stressed metal (such as aluminum) is deposited on it and annealed under controlled conditions to create a predetermined curvature, with a warpage height of approximately 400 nm. Finally, under a microscope, using a precision tungsten probe micromanipulator, this warped superslip sheet is transferred to the center of an insulating dielectric layer, allowing it to naturally adhere to an atomically smooth surface. In its natural state, the warped superslip sheet partially covers the first driving electrode, the common ground electrode, and the second driving electrode.

[0084] To achieve the objectives of this invention, based on the above embodiments, another embodiment of this application provides a switch driving method. In the off state, when it is necessary to turn off the radio frequency signal in the right branch, a driving voltage V1 (e.g., a 20V DC voltage or pulse voltage) is applied between the second driving electrode and the common ground electrode. The resulting electrostatic force attracts the right side of the warped superslipper to move downwards, causing the entire superslipper to warp to the right with the middle as the fulcrum, thereby separating its left side from the left radio frequency signal electrode, achieving the off state, at which time the radio frequency signal path is disconnected.

[0085] In the open state, when it is necessary to connect the right branch RF signal, V1 is removed, and a driving voltage V2 is applied between the first driving electrode and the common ground electrode. The electrostatic force attracts the left side of the warped superslipper to move downward, causing it to warp to the left, while its right edge reliably contacts the right RF signal electrode, thus achieving the open state and enabling the RF signal to conduct.

[0086] To optimize the dynamic performance of the switch (such as reducing impact and increasing speed), the pulse waveform can be optimized for driving. For example, a high-amplitude short pulse (e.g., 25V, 50ns) can be applied first to achieve rapid start-up, followed by switching to a lower sustaining voltage (e.g., 10V) to maintain stability and reduce energy consumption and system oscillation.

[0087] Example 1

[0088] A single warped superslipper has a size of 25*25μm. The spacing between the RF signal electrodes is 70μm. The size of the driving electrode and the ground electrode are 25*10μm and 25*3μm, respectively, with a spacing of 1μm between each pair. The thickness of the insulating dielectric layer is 100nm, and the driving voltage is about 30V.

[0089] The preferred radio frequency signal electrode is a gold electrode prepared by evaporation process with an electrode thickness of 20 nm, ensuring that the electrode surface roughness Ra < 0.8 nm, increasing the contact area between the warped superslipper and the radio frequency signal electrode, reducing contact resistance, reducing insertion loss, and improving linearity.

[0090] Example 2

[0091] Two warped superslippers, each 25*25μm in size, are used. The RF electrodes are spaced 70μm apart. The driving electrode and ground electrode are 25*10μm and 25*3μm in size, respectively, with a 1µm gap between each pair. The insulating dielectric layer is 100nm thick, and the driving voltage is approximately 30V.

[0092] The preferred radio frequency signal electrode is a gold electrode prepared by evaporation process with an electrode thickness of 20 nm, ensuring that the electrode surface roughness Ra < 0.8 nm, increasing the contact area between the warped superslipper and the radio frequency signal electrode, reducing contact resistance, reducing insertion loss, and improving linearity.

[0093] To achieve the objective of this invention, in another embodiment of this application, a method for manufacturing a switch is provided, the method comprising the following steps:

[0094] Step S101: Provide a high-resistivity silicon insulating substrate and perform standard cleaning.

[0095] Step S102: The first driving electrode, the second driving electrode, and the common ground electrode are patterned on the substrate by photolithography, sputtering / evaporation, and lift-off processes.

[0096] Step S103: Using PECVD process, deposit a silicon nitride insulating dielectric layer with a thickness of about 1.1 μm on the entire substrate.

[0097] Step S104: Perform chemical mechanical polishing on the surface of the insulating dielectric layer. Key process parameters include: using a silica-based polishing slurry, a polishing pressure of 3 psi, a polishing disc rotation speed of 90 rpm, and controlling the process through endpoint detection. The silicon nitride layer is ultimately thinned to approximately 100 nm, resulting in an atomically smooth surface with Ra < 0.8 nm.

[0098] Step S105: Apply protective adhesive to the surface of the polished insulating dielectric layer, etch a portion of the insulating dielectric layer on the driving electrode, and expose the driving electrode for the next connection step.

[0099] Step S106: The external power supply electrodes of the first driving electrode, the second driving electrode, and the common ground electrode are patterned on the insulating dielectric layer by photolithography, sputtering / evaporation, and lift-off processes.

[0100] Step S107: A gold radio frequency signal electrode and its metallization layer are formed on the polished insulating dielectric layer through photolithography and electroplating processes.

[0101] Step S108: Using a microprobe transfer system, under micromanipulation, the warped superslippery sheet is picked up from the source substrate and precisely released to a predetermined position in the insulating dielectric layer 2, relying on van der Waals forces to complete self-adsorption and fixation.

[0102] To achieve the objectives of this invention, in another embodiment of this application, a radio frequency (RF) front-end system is provided, such as a beamforming module for a 5G base station. This module includes multiple ultra-slippery RF switches with the structure described in the above embodiments. These switches are integrated onto a multi-functional chip, and by controlling the opening and closing states of different switches, the phase and amplitude of the RF signal are modulated, thereby guiding the beam direction. Because the switches of this invention have the advantages of low insertion loss, high isolation, high linearity, and high power capacity, this RF front-end system can significantly improve the signal coverage quality and energy efficiency of the base station.

[0103] This technology innovatively introduces structural superslippery technology into the design of radio frequency microelectromechanical switches, constructing an anchor-free warping structure. Utilizing the near-zero friction and zero-wear motion characteristics of the warped superslipper on an atomically smooth interface, it fundamentally solves the two core problems of contact wear and stickiness and cantilever beam speed limitation in traditional switches. It successfully achieves a synergistic improvement in nanosecond-level high-speed switching, over 100 million cycle life, extremely low insertion loss below 0.2dB, and watt-level high-power transmission capability. At the same time, its all-planar structure significantly simplifies micro-nano manufacturing processes, providing a high-performance and high-reliability RF front-end key device solution for 5G / 6G communication systems.

[0104] The greatest advantage of this solution lies in its nanosecond-level switching response time. Using a Polytec Doppler laser vibrometer to synchronize the voltage output and laser detection of the warped superslipper's normal-direction motion, the motion signal detected by the laser during pulsed voltage application is almost synchronous with the voltage signal on the time axis. The time interval between the end of the motion and the completion of the voltage application is approximately 500 ns. After subsequently eliminating the signal delay from the voltage amplifier in the test circuit, this can be reduced to 100–200 ns, a response speed that is difficult to achieve with traditional cantilever beam MEMS RF switches. Furthermore, reducing the thickness of the insulating dielectric layer and the driving voltage is expected to further accelerate the response time. During the switching motion, the warped superslipper experiences virtually no deformation. Unlike the forced deformation structure of a cantilever beam, this warped superslipper can withstand more switching cycles and achieve faster switching speeds.

[0105] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A structurally super-slippery, anchor-free, tilting radio frequency microelectromechanical switch, characterized in that, include: An insulating substrate, and a driving electrode structure disposed on the insulating substrate; There is also an insulating dielectric layer covering the driving electrode structure; The anchorless tilting radio frequency microelectromechanical switch further includes a radio frequency electrode structure disposed on the insulating dielectric layer, and at least one warped superslipper on the surface of the insulating dielectric layer. The middle section of the warped superslipper is adsorbed onto the surface of the insulating dielectric layer, and the two ends of the warped superslipper warp and move to be movably attached to the radio frequency electrode structure, respectively. The radio frequency electrode structure includes at least one radio frequency signal electrode and a ground electrode, forming a coplanar waveguide structure. Under the electrostatic driving force applied by the driving electrode structure, the warped superslipper warps relative to the insulating dielectric layer and controls the contact conduction or separation with the radio frequency signal electrode in real time.

2. The anchorless tilting radio frequency microelectromechanical switch based on structural superslippery as described in claim 1, characterized in that, The driving electrode structure includes a first driving electrode and a second driving electrode, and a first ground electrode or a second ground electrode disposed between them. The first driving electrode and the second driving electrode are arranged symmetrically, and the warped superslipper covers part of the first driving electrode, part of the first ground electrode and part of the second driving electrode in its natural state.

3. The anchorless tilting radio frequency microelectromechanical switch based on structural superslippery as described in claim 1 or 2, characterized in that, The number of the warped superslipper is two, each corresponding to a different radio frequency signal electrode; When a voltage is applied to the first driving electrode and the third driving electrode, and the first ground electrode and the second ground electrode are grounded, the two warped superslippers tilt upwards toward both ends of the device, separating from the radio frequency signal electrode, and the switch is in the off state. When a voltage is applied to the second driving electrode and the first and second grounding electrodes are grounded, the two warped superslippers tilt toward the middle of the device and come into contact with the radio frequency signal electrode, and the switch is in the open state.

4. The anchorless tilting radio frequency microelectromechanical switch based on structural superslippery as described in claim 3, characterized in that, The warped superslipper is a micron-scale sheet structure with a preset curvature; its curvature is formed by the thermal stress mismatch of its own multilayer material; wherein, the cross-section of the warped superslipper is arc-shaped or approximately arc-shaped; The material of the warped superslip sheet includes at least one of graphene, molybdenum disulfide, and boron nitride.

5. The anchorless tilting radio frequency microelectromechanical switch based on structural superslippery as described in claim 4, characterized in that, The warped superslipper has a square structure with a side length of 10–50 μm; The long side dimension of the electrode in the driving electrode structure matches the side length of the warped superslipper, which is 10-50 μm, and the spacing between the electrodes is 1-10 μm; The material of the warped super-slippery sheet is highly oriented pyrolytic graphite or multilayer graphene.

6. The anchorless tilting radio frequency microelectromechanical switch based on structural superslippery as described in claim 1, characterized in that, The radio frequency electrode structure is made of gold, with a thickness of 5nm to 30nm and an electrode resistance of less than 0.5 ohms. The surface roughness Ra of the contact surface between the radio frequency electrode structure and the warped superslipper is <0.8 nm.

7. The anchorless tilting radio frequency microelectromechanical switch based on structural superslippery as described in claim 1, characterized in that, The insulating dielectric layer is made of silicon nitride, hafnium oxide, or silicon oxide. The thickness of the insulating dielectric layer is 50–300 nm.

8. A method for driving the radio frequency microelectromechanical switch according to any one of claims 1 to 7, characterized in that, include: A first driving voltage is applied to the first group of driving electrodes, and the corresponding grounding electrode is grounded, driving the warped superslipper to warp in the first direction and separate from the radio frequency signal electrode, and the switch is in the off state. A second driving voltage is applied to the second set of driving electrodes, and the corresponding grounding electrode is grounded, driving the warped superslipper to warp in a second direction opposite to the first direction, making contact with the radio frequency signal electrode, and the switch is in the on state.

9. A method for manufacturing a radio frequency microelectromechanical switch as described in any one of claims 1 to 7, characterized in that, Including the following steps: A driving electrode structure is fabricated on an insulating substrate; and an insulating dielectric layer is deposited to cover the driving electrode structure and the substrate. The surface of the insulating dielectric layer is subjected to chemical mechanical polishing to form an atomically smooth surface; wherein, during chemical mechanical polishing, the surface roughness of the insulating dielectric layer is controlled to be Ra<2nm; A radio frequency electrode structure is fabricated on a polished insulating dielectric layer; and a pre-fabricated warped superslipper is transferred and fixed to a predetermined position on the insulating dielectric layer; wherein the warped superslipper is transferred and placed using microprobe transfer technology.

10. A radio frequency front-end system, characterized in that, It integrates at least one anchor-free tilting radio frequency microelectromechanical switch based on structural superslippery as described in any one of claims 1 to 7.

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