A direct heating type reconfigurable intelligent metasurface based on phase change material and a preparation method thereof

Abstract

The application provides a direct heating type reconfigurable intelligent metasurface based on a phase change material and a preparation method thereof, the metasurface is composed of a plurality of metasurface units arranged in an array, each metasurface unit comprises, from bottom to top, a substrate, a first dielectric layer, an intermediate metal layer, a second dielectric layer and a phase change material layer; the phase change material layer is provided with metal patches of a metal radiating patch structure on both sides; the substrate is provided with a contact electrode; the first dielectric layer and the second dielectric layer are insulating layers, the metasurface unit is further provided with a first vertical through hole and a second vertical through hole, and the metal patch radiating structure forms an electric current path with the contact electrode of the substrate through the first vertical through hole and the second vertical through hole; the electric current flows through the phase change material layer, drives the phase change material to occur crystal / amorphous state conversion, and changes the equivalent conductive path, electromagnetic coupling strength or local impedance between the metal patch radiating structures in different phase states.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic metamaterials technology, specifically relating to a direct-heating reconfigurable smart metasurface based on phase change materials and its preparation method. Background Technology

[0002] Reconfigurable smart metasurfaces enable programmable control of the amplitude, phase, and polarization of unit cells, achieving beamforming, environmental reconfiguration, and multifunctional electromagnetic control, making them a key technology for 6G. Their core lies in the performance and programmability of the tunable unit structure. Current mainstream implementation schemes include PIN diodes, varactor diodes, and MEMS switches, but all have limitations: PIN diodes are mostly two-state switches with low phase resolution, and combined schemes increase unit size and losses; varactor diodes require continuous bias to maintain their state, resulting in static power consumption and limited tuning linearity; MEMS switches have slow switching speeds, are susceptible to mechanical fatigue, and struggle to achieve reliable high-density arrays.

[0003] Phase change materials (PCMs) have emerged as a new approach to achieving low power consumption and high speed due to their reversible switching between crystalline and amorphous states, non-volatility, and significant differences in dielectric constant. However, current research on PCM metasurfaces remains limited: one type uses volatile materials, which cannot maintain the set state and do not fully utilize the advantages of non-volatility; the other type relies on external laser-induced phase transitions, resulting in complex systems that are difficult to integrate in arrays, thus restricting engineering applications.

[0004] Therefore, there is still a lack of a programmable metasurface cell structure that can utilize non-volatile PCMs, achieve low power consumption and high reliability through electrical or thermal body excitation, and is suitable for integrated arrays. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a direct-heating reconfigurable smart metasurface based on phase change materials and its preparation method.

[0006] This invention provides the following technical solution:

[0007] This invention provides a direct-heating reconfigurable smart metasurface based on phase change material. The metasurface is composed of multiple metasurface units arranged in an array. Each metasurface unit includes, from bottom to top, a substrate, a first dielectric layer, an intermediate metal layer, a second dielectric layer, and a phase change material layer. Metal patches with metal radiation patch structures are respectively provided on both sides of the phase change material layer, with one side of the metal patch located below the phase change material layer and the other side of the metal patch located above the phase change material layer.

[0008] The substrate is provided with a contact electrode that is electrically connected to the feed network; the metasurface unit is also provided with a first vertical through hole and a second vertical through hole. The upper end of the first vertical through hole is connected to a metal patch on one side of the metal patch radiating structure, and the lower end of the first vertical through hole is connected to the upper surface of the intermediate metal layer. The upper end of the second vertical through hole is connected to a metal patch on the other side of the metal patch radiating structure, and the lower end of the second vertical through hole is connected to the contact electrode.

[0009] The first and second dielectric layers are insulating layers. An electrical path is formed between the contact electrode and the metal patches on both sides of the metal patch radiating structure. Current flows through the phase change material layer to drive the phase change material to undergo a crystalline / amorphous state transition by direct heating. Under different phase states, the equivalent conductive path, electromagnetic coupling strength, or local impedance between the metal patch radiating structures is changed.

[0010] In this invention, a phase change material is sandwiched between two metal patches and electrically contacts them to form a metal-dielectric-metal (MIM) stacked structure. The metal patch radiating structure forms an electrical path with the contact electrode of the substrate through the first and second vertical through holes. The current flowing through the phase change material achieves heating. The phase change material is driven to undergo a crystalline / amorphous state transition by direct heating, thereby changing the coupling state, current distribution or local impedance between the patches, achieving different phase delays or phase differences, and thus controlling the reflection phase or transmission phase of the metasurface unit.

[0011] Furthermore, the phase change material is a chalcogenide compound or a chalcogenide compound doped with one or more of the elements Se, Bi, Sn, N, In, Hf, Y, Sc, Ga, and Ti, and the chalcogenide compound includes germanium telluride, antimony telluride, and germanium-antimony-telluride.

[0012] Furthermore, the first vertical through-hole penetrates the second dielectric layer, and the second vertical through-hole penetrates the second dielectric layer, the intermediate metal layer, and the first dielectric layer. The intermediate metal layer is provided with an insulating clearance area, and the second vertical through-hole passes through the insulating clearance area.

[0013] Furthermore, the metal patch radial structure is one of a bow-shaped patch, a double-patch structure, or a multi-region patch topology. This invention is applicable to patch structures with bow-shaped, double-patch, or other two-sided distributed topologies, and also supports different phase change material layouts such as MIM or vias.

[0014] Furthermore, both the first vertical through hole and the second vertical through hole are filled with one or more of copper and tungsten.

[0015] Furthermore, the dielectric of the first dielectric layer includes one of silicon dioxide, silicon nitride, and aluminum nitride; the dielectric of the second dielectric layer includes one of silicon dioxide, silicon nitride, and aluminum nitride.

[0016] Furthermore, the substrate comprises one or more of the following: high-resistivity silicon, diamond, sapphire, silicon carbide, indium phosphide, gallium arsenide, gallium nitride, quartz, and glass.

[0017] Furthermore, the intermediate metal layer comprises one or more of gold, copper, silver, aluminum, or platinum.

[0018] Furthermore, the contact electrode is composed of one or more of gold, copper, silver, aluminum, and platinum; the metal patch is composed of one or more of gold, copper, silver, aluminum, and platinum.

[0019] This invention also provides a method for preparing the above-mentioned direct-heating reconfigurable smart metasurface based on phase change materials, comprising the following steps:

[0020] S1. Fabricate contact electrodes in the substrate;

[0021] S2. Deposit a first dielectric layer over the substrate, deposit an intermediate metal layer over the first dielectric layer, and deposit a second dielectric layer over the intermediate metal layer.

[0022] S3. Prepare a first vertical through-hole and a second vertical through-hole in the first dielectric layer, the intermediate metal layer and the second dielectric layer;

[0023] S4. Prepare a metal patch on one side of the metal radiation patch structure above the second medium;

[0024] S5. Deposit a phase change material layer on top of a metal patch on one side of the metal radiation patch structure;

[0025] S6. Prepare a metal patch on the other side of the metal radiation patch structure above the phase change material layer.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention integrates a phase change material layer and a metal patch radiation structure on a second dielectric layer, and works with a lower power supply network to achieve a bottom-up controllable structural design for the unit. By utilizing the reversible switching of the phase change material between crystalline and amorphous states, a controllable conductive path can be formed inside the unit, thereby adjusting the coupling state or local current distribution between patches and realizing programmable phase control of the unit and array.

[0028] 2. The phase change material of this invention can maintain the set state without continuous bias, effectively reducing static power consumption; it also has high-precision phase control capability: by changing the conductive path and patch coupling state, the phase modulation of the unit and array can be realized, improving the beam control accuracy.

[0029] 3. The unit cells of the metasurface structure of the present invention can be arranged in an array, which can realize large-area metasurface control and facilitate the application of reflective, transmissive or hybrid reflective-transmissive tunable metasurfaces.

[0030] 4. The power supply network and via design in this invention are directly compatible with PCB or semiconductor processes, facilitating mass production and integrated applications;

[0031] 5. The present invention provides a reconfigurable smart metasurface structure based on phase change materials, which realizes low power consumption, high reliability and high precision multi-bit phase modulation, and provides a highly engineering feasible technical solution for millimeter wave / terahertz antennas, intelligent electromagnetic environment construction and future 6G communication. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0033] Figure 1 A three-dimensional structural schematic diagram of a reconfigurable smart metasurface unit based on phase change materials provided in an embodiment of the present invention;

[0034] Figure 2 A front cross-sectional view of the reconfigurable smart metasurface unit based on phase change materials provided in an embodiment of the present invention;

[0035] Figure 3 A side cross-sectional view of a reconfigurable smart metasurface unit based on phase change materials provided in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of the connection structure between the phase change material layer and the metal radiation patch structure in a reconfigurable smart metasurface unit based on phase change material provided in an embodiment of the present invention;

[0037] Figure 5 The images show a top view and a detailed view of the top-level radiative patch structure of a reconfigurable smart metasurface based on phase change materials, provided in an embodiment of the present invention.

[0038] Figure 6 These are simulation diagrams of the phase response of the metasurface unit under two different states in an embodiment of the present invention;

[0039] Figure 7 The above are simulation diagrams of the amplitude response of the metasurface unit under two different states in an embodiment of the present invention.

[0040] In the figure: 1-substrate; 101-contact electrode; 2-first dielectric layer; 3-intermediate metal layer; 4-second dielectric layer; 5-phase change material layer; 61-first metal radiating patch; 62-second metal radiating patch; 71-first vertical via; 72-second vertical via. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1:

[0043] like Figure 1-5 As shown, the metasurface unit of this embodiment includes, from bottom to top, a substrate 1, a first dielectric layer 2, an intermediate metal layer 3, a second dielectric layer 4, a phase change material layer 5, and a first metal radiating patch 61 and a second metal radiating patch 62 of a metal patch radiating structure, wherein the first metal radiating patch 61 and the second metal radiating patch 62 are respectively disposed on both sides of the phase change material layer 5; the above-mentioned multiple metasurface units can be arranged in an array to form a metasurface structure.

[0044] The first dielectric layer 2 is located on the substrate 1, the intermediate metal layer 3 is located on the first dielectric layer 2, and the second dielectric layer 4 is located on the intermediate metal layer 3. The first metal radiating patch 61 and the second metal radiating patch 62 are located on the upper surface of the second dielectric layer 4. The patches are not in direct contact but have a gap between them. The phase change material layer 5 is disposed at this gap, connecting the metal radiating patches 61 and 62 in the vertical direction to form a MIM structure (see [link to MIM structure]). Figure 4 ).

[0045] The substrate 1 contains a contact electrode 101 for transmitting control signals; the intermediate metal layer 3 serves as a ground layer or transmits a second control signal.

[0046] The first vertical through-hole 71 and the second vertical through-hole 72 are used to achieve vertical electrical interconnection: the first vertical through-hole 71 penetrates the second dielectric layer 4, its top end is physically and electrically connected to the second metal radiating patch 62, and its bottom end is connected to the intermediate metal layer 3; the second vertical through-hole 72 penetrates the second dielectric layer 4, the intermediate metal layer 3 and the first dielectric layer 2, its top end is physically and electrically connected to the first metal radiating patch 61, and its bottom end is connected to the contact electrode 101; in addition, an isolation structure 301 (i.e., through-hole avoidance area) is provided in the intermediate metal layer 3 around the position of the vertical through-hole 72. This area is filled with an insulating medium, and the aperture in the horizontal direction is larger than the aperture of the second vertical through-hole 72, so as to ensure that the second vertical through-hole 72 remains insulated when passing through the intermediate metal layer 3 and prevent short circuit. In this embodiment, the insulating clearance area 301 is ring-shaped and is made of insulating material (such as alumina, aluminum nitride, silicon dioxide, etc.). In other embodiments, the shape of the insulating clearance area 301 is sufficient to surround the second vertical through hole for insulation, and no special design is required for its shape.

[0047] In this embodiment, the selection of materials for each structural layer follows the following principles:

[0048] Phase change materials need to possess significant reversible phase change characteristics, a large conductivity change ratio, good cycle stability, and compatibility with micro / nano fabrication processes; dielectric layer materials need to have good electrical isolation performance, low dielectric strength, and thermal stability to achieve effective isolation between heating circuits and radio frequency circuits; intermediate metal layers and metal patches need to have high conductivity to reduce losses; substrate materials need to have low dielectric loss, high thermal conductivity, or good process compatibility to meet the application requirements of millimeter-wave / terahertz bands.

[0049] In this embodiment, the phase change material is germanium-antimony-tellurium (Ge2Sb2Te5, GST), which has a significant difference in conductivity between its amorphous and crystalline states, enabling effective control of the reflection phase and amplitude of the metasurface unit. The first dielectric layer is alumina (Al2O3), and the second dielectric layer is silicon dioxide, used to achieve electrical isolation between the heating electrode and the contact electrode. The intermediate metal layer is copper (Cu) to reduce ohmic losses in the interconnection path between the feed network and the metal patch radiating structure. The contact electrode is gold (Au) to improve ohmic contact performance with the phase change material and the metal patch radiating structure. The substrate is a high-resistivity silicon substrate, balancing process maturity and RF performance. The metal radiating patch layer is made of copper or gold to form the radiating structure of the metasurface unit, enabling electromagnetic wave phase modulation.

[0050] In other optional embodiments, the substrate 1 includes, but is not limited to, one or more of high-resistivity silicon, diamond, silicon carbide, indium phosphide, gallium arsenide, gallium nitride, quartz, and glass; the contact electrode 101 includes, but is not limited to, one or more of high-conductivity metal materials such as gold, copper, silver, aluminum, and platinum; the first dielectric layer 2 includes, but is not limited to, one or more of silicon dioxide, silicon nitride, and aluminum nitride; the intermediate metal layer 3 includes, but is not limited to, one or more of high-conductivity metal materials such as gold, copper, silver, aluminum, and platinum; the second dielectric layer 4 includes, but is not limited to, one or more of silicon dioxide, silicon nitride, and aluminum nitride; the first vertical via 71 and the second vertical via 72 include, but are not limited to, one or more of copper and tungsten; the phase change material is a chalcogenide compound, or a chalcogenide compound doped with one or more of elements such as indium, hafnium, yttrium, scandium, gallium, and titanium, wherein the chalcogenide compound includes germanium telluride, antimony telluride, and germanium-antimony-tellurium; the metal radiation patch layers 61 and 62 include, but are not limited to, one or more of high-conductivity metal materials such as gold, copper, silver, aluminum, and platinum.

[0051] It should be noted that the metal patch radiating structure in this invention can not only adopt the bow-shaped patch structure used in Example 1, but also a double patch structure or a multi-region patch topology structure, ensuring that the two sides of the metal patch radiating structure are connected to the phase change material layer 5 and form a structure as shown in the figure. Figure 4 The MIM structure shown is sufficient.

[0052] Example 2:

[0053] In this embodiment, a method for preparing the reconfigurable smart metasurface based on phase change materials as described in Example 1 is provided, and the specific steps are as follows:

[0054] S1: A bottom contact electrode is fabricated on substrate 1. High-resistivity silicon is selected as substrate 1. After cleaning substrate 1, a bottom electrode window is defined at a predetermined position on the substrate surface using photolithography and etching processes. A metal layer Cr / Au (Cr is used as an adhesion layer in conventional deposition processes to ensure the reliability of material deposition) is deposited using photolithography and electron beam evaporation deposition processes, and then peeled off to form contact electrode 101. The materials selected above are only one specific embodiment; substrate 1 can also be one or more of high-resistivity silicon, diamond, silicon carbide, indium phosphide, gallium arsenide, gallium nitride, quartz, and glass.

[0055] S2: Prepare a first dielectric layer 2 on substrate 1. Specifically, use plasma enhanced chemical vapor deposition (PECVD) to deposit the first dielectric layer 2 aluminum oxide on substrate 1. The first dielectric layer 2 can also be one of silicon dioxide, silicon nitride, and aluminum nitride.

[0056] S3: An intermediate metal layer 3 is deposited above the first dielectric layer 2. Specifically, copper is deposited using an electron beam evaporation deposition process, and patterned using photolithography and etching processes to define the avoidance area 301 of the via, forming an intermediate bias / ground signal layer. The intermediate metal layer 3 can also be one or more of the following metal materials with high electrical conductivity: gold, copper, silver, aluminum, platinum, etc.

[0057] S4: A second dielectric layer 4 is deposited above the intermediate metal layer 3. Specifically, silicon dioxide is deposited by PECVD as an insulating layer and chemical mechanical polishing (CMP) is performed to achieve surface planarization. The second dielectric layer 4 can also be one of aluminum oxide, silicon nitride, and aluminum nitride.

[0058] S5: In the above structure, a first vertical via 71 and a second vertical via 72 are fabricated. Specifically, the vertical vias are fabricated using photolithography and deep reactive ion etching (DRIE) processes. Through step-by-step etching or by using etch stop layers of different depths, the first etching depth reaches the surface of the intermediate metal layer 3 to obtain the first vertical via 71. The second etching depth penetrates the intermediate metal layer 3 and the first dielectric layer 2, reaching the contact electrode 101 to obtain the second vertical via 72. The vias are filled with copper using an electroplating process, and then CMP polishing is performed to remove excess metal from the surface, completing the fabrication of the first vertical via 71 and the second vertical via 72. The filling materials for the first vertical via 71 and the second vertical via 72 include, but are not limited to, one or more of copper and tungsten.

[0059] S6: A first metal radiating patch 61 is fabricated above the second dielectric layer 4. The pattern of the first metal radiating patch 61 is defined using a photolithography process. Titanium and gold are deposited sequentially using an electron beam evaporation deposition process. The photoresist and excess metal are removed using a lift-off process to form the first metal radiating patch 61. The first metal radiating patch 61 is a metallic material, including but not limited to one or more of the following metal materials with high electrical conductivity: gold, copper, silver, aluminum, platinum, etc.

[0060] S7: A phase change material layer 5 is deposited above the metal radiating patch 61. Ge2Sb2Te5 is deposited as the phase change material layer 5 above the metal radiating patch 61 using magnetron sputtering. The phase change material is patterned using photolithography, and the phase change material outside the patterned area is etched away. After removing the resist, the fabrication of the phase change material layer 5 is complete. In other embodiments, the phase change material is selected from chalcogenide compounds or chalcogenide compounds doped with one or more elements such as indium, hafnium, yttrium, scandium, gallium, and titanium. Chalcogenide compounds include germanium telluride, antimony telluride, and germanium-antimony-telluride.

[0061] S8: A second metal radiating patch 62 is fabricated above the second dielectric layer 4 and the phase change material layer 5. The pattern of the second metal radiating patch 62 is defined using a photolithography process. Titanium and gold are sequentially deposited using an electron beam evaporation deposition process. The photoresist and excess metal are removed using a lift-off process to form the second metal radiating patch 62. The second metal radiating patch 62 is a metallic material, including but not limited to one or more metals with high electrical conductivity such as gold, copper, silver, aluminum, and platinum. At this time, the phase change material layer 5 is located between the first radiating patch 61 and the second radiating patch 62. The tops of the first vertical via 71 and the second vertical via 72 are electrically connected to the two metal radiating patches, respectively.

[0062] This invention employs a direct heating mode, where a DC pulse voltage is applied between the intermediate metal layer 3 and the contact electrode 101. Current flows sequentially through the first vertical through-hole 71, the first metal radiating patch 61, the phase change material layer 5, the second metal radiating patch 62, and the second vertical through-hole 72. Joule heating is generated as the current flows through the phase change material layer 5, controlling the phase change material to switch between a crystalline (low resistivity) and an amorphous (high resistivity) state.

[0063] When the phase change material layer 5 is in a crystalline state, it has a low resistance. The first metal radiating patch 61 and the second metal radiating patch 62 are connected through the phase change material layer 5, and the unit exhibits a first electromagnetic response state.

[0064] When the phase change material layer 5 is in an amorphous state, it has a high resistance, and the first metal radiating patch 61 and the second metal radiating patch 62 are disconnected, with the unit exhibiting a second electromagnetic response state. By utilizing the difference in impedance characteristics of the phase change material layer 5 in different states, the phase of the incident electromagnetic wave can be reconfigurably controlled.

[0065] The reconfigurable metasurface unit of this invention introduces a phase change material between metal patch structures and utilizes electrical or thermal excitation to trigger the crystallization and amorphization processes of the phase change material, thereby achieving single-bit programmable control of the unit's reflection or transmission phase. The phase change material exhibits significant differences in conductivity in different states. When in the crystalline state, it has high conductivity, which can form an effective conductive path between the metal patch regions; when in the amorphous state, it has high resistance, and the equivalent coupling between the patches is weakened or broken, thus forming two stable states with significant phase differences.

[0066] In one implementation, single-bit phase switching is achieved by completely switching the phase change material between a crystalline and amorphous states. When the phase change material transitions from an amorphous to a crystalline state, a wide-pulse, high-voltage, or high-power excitation is applied through a feeding network, causing the entire phase change material to heat up to its crystallization temperature range and maintain this temperature for a sufficient time. This transforms the disordered atomic structure within the material into an ordered lattice structure, thereby forming a continuous crystalline region in the phase change material area. At this point, the phase change material exhibits high conductivity, a stable conductive path is formed between the regions on both sides of the metal patch, the equivalent impedance of the metasurface unit changes, and the reflection or transmission phase jumps to the first state. The crystalline state is non-volatile and can be maintained for a long time without external bias.

[0067] When a phase change material (PCM) reverts from a crystalline to an amorphous state, a narrow-pulse, high-voltage excitation is applied, causing the material to locally and instantaneously heat up to its melting temperature. Following rapid quenching after the excitation, a disordered structure is formed. This process causes the PCM to re-enter the amorphous state, exhibiting high impedance characteristics. The conductive paths between the patch structures are interrupted or significantly weakened, and the reflection phase of the unit cells jumps to a second state. Combined with... Figure 6 It can be seen that the reflection phase curve corresponding to the amorphous state is generally located in the high phase range, maintaining a clear and stable phase interval with the crystalline state curve within the target operating frequency band. This indicates that the unit can form a distinguishable discrete phase response in both states. The phase difference between the crystalline and amorphous states depends on the unit structure design and the phase change material parameters, which can be illustrated by the simulation results of the phase difference and return loss in the attached figures. Both states can remain stable after the external excitation is removed, exhibiting non-volatility and repeatability.

[0068] Furthermore, such as Figure 7 As shown, within the same frequency band, the metasurface unit maintains a low amplitude loss level in both crystalline and amorphous states. The reflection amplitude changes smoothly with frequency without drastic fluctuations, indicating that the phase change material state switching does not introduce significant additional losses. Compared to the amorphous state, the reflection amplitude changes slightly in the crystalline state due to the formation of the conduction path, but it remains within an acceptable range overall, which is beneficial for maintaining amplitude-phase consistency in array-level applications.

[0069] Taking a reflective tunable metasurface as an example, when the phase change material is in a crystalline state, its high conductivity allows the bow-shaped metal patch to form a continuously conducting current path, and the unit exhibits an equivalent radiation structure with a large electrical size, corresponding to the first reflection phase state (e.g., 0°). When the phase change material transforms into an amorphous state, its conductivity significantly decreases, the current path in the central region of the patch is effectively broken, the current distribution path within the unit changes, the equivalent electrical size of the unit decreases, and its resonant characteristics change accordingly, thus corresponding to the second reflection phase state (e.g., 180°) at the same operating frequency. In the parameter design of this embodiment, by synergistically optimizing the geometric dimensions of the metal patch and the size of the phase change region, the reflection phase difference between the two states near the approximately 90 GHz operating frequency band is made close to 180°, thereby realizing 1-bit digital phase encoding for programmable control of the reflected electromagnetic wavefront.

[0070] In a transmissive tunable metasurface structure, a phase change material is placed between upper and lower metal patches or a slot coupling structure. Its phase change is used to adjust the electromagnetic coupling strength and equivalent impedance characteristics inside the unit.

[0071] When the phase change material is in a crystalline state, the unit cell forms a strong coupling channel for the incident electromagnetic wave, enabling the transmitted wave to acquire a first transmission phase state. When the phase change material is in an amorphous state, the coupling within the unit cell weakens or is effectively shut off, and the transmitted wave acquires a second transmission phase state different from the aforementioned first transmission phase state. By designing the unit cell structural parameters, discrete transmission phase switching can be achieved within the target frequency band, which can be used to construct a programmable transmission array.

[0072] In array applications, the unit structure of this invention can be arranged in a two-dimensional array. By writing different crystallization area states to different units, multi-level control of the reflected or transmitted wavefront can be achieved, which can be used for applications such as beamforming, wide-angle scanning, sidelobe suppression, or multi-functional electromagnetic field control. Since all states of the phase change material are non-volatile, the array can still maintain the set wavefront distribution after the external excitation is removed, thereby significantly reducing system power consumption and improving the reliability and environmental adaptability of array operation.

[0073] Figure 5 This is a top view of the top-layer radiative patch structure and the phase change material layer of a reconfigurable smart metasurface based on phase change materials provided in an embodiment of the present invention. In an optional embodiment, the metal patch is as follows: Figure 5 As shown in the bow-shaped diagram, the first metal radiating patch 61 and the second metal radiating patch 62 are axially symmetrically distributed, and the phase change material layer 5 is located at the central connection point of the two patches. By optimizing the dimensions L1, L2, and L3, the resonant frequency and phase coverage range of the metasurface unit can be adjusted. The phase change material layer 6 is located between the two patches, with a width of W1 and a length of W2.

[0074] To verify the phase response capability of the reconfigurable smart metasurface unit to electromagnetic signals in the embodiments of the present invention, a model of the reconfigurable smart metasurface unit based on phase change material was established using HFSS software, and the phase response characteristics of the reconfigurable smart metasurface unit with the phase change material in different states were simulated. In an optional embodiment, the patch dimensions are L1=200um, L2=300um, and L3=100um, and the width of the phase change material layer is W1=15um and the length is W2=15um.

[0075] This invention introduces a DC power supply network below the radiating unit using vertical through-hole technology, realizing a directly heated phase-change radio frequency switch unit. This effectively reduces the interference of the power supply network on electromagnetic waves and improves the integration of the structure.

[0076] This invention has several outstanding effects:

[0077] (1) Low power consumption and non-volatility: Phase change materials can maintain the set state without continuous bias, effectively reducing static power consumption;

[0078] (2) High-precision phase control: By changing the conductive path and patch coupling state, the phase modulation of the unit and array is realized, thereby improving the beam control accuracy;

[0079] (3) Strong structural versatility: It is suitable for patch structures with bows, double patches or other patch topologies distributed on both sides, and supports different phase change material layouts such as MIM or pinholes;

[0080] (4) Array-level scalability: The units can be arrayed to achieve large-area metasurface control, which is convenient for reflective, transmissive or hybrid applications;

[0081] (5) Engineering implementation: The power supply network and via design can be directly compatible with PCB or semiconductor processes, facilitating mass production and integrated applications.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A directly heated reconfigurable smart metasurface based on phase change materials, characterized in that, The metasurface is composed of multiple metasurface units arranged in an array. Each metasurface unit includes, from bottom to top, a substrate, a first dielectric layer, an intermediate metal layer, a second dielectric layer, and a phase change material layer. Metal patches with a metal radiation patch structure are respectively provided on both sides of the phase change material layer. One side of the metal patch is located below the phase change material layer, and the other side of the metal patch is located above the phase change material layer. The metal patches on both sides are located on the upper surface of the second dielectric layer and have no direct contact with each other, but have gaps. The phase change material layer is disposed at the gaps and connects the metal patches on both sides in the vertical direction. The substrate is provided with a contact electrode that is electrically connected to the feed network; the metasurface unit is also provided with a first vertical through hole and a second vertical through hole. The upper end of the first vertical through hole is connected to a metal patch on one side of the metal patch radiating structure, and the lower end of the first vertical through hole is connected to the upper surface of the intermediate metal layer. The upper end of the second vertical through hole is connected to a metal patch on the other side of the metal patch radiating structure, and the lower end of the second vertical through hole is connected to the contact electrode. The first and second dielectric layers are insulating layers. An electrical path is formed between the contact electrode and the metal patches on both sides of the metal patch radiating structure. Current flows through the phase change material layer to drive the phase change material to undergo a crystalline / amorphous state transition by direct heating. Under different phase states, the equivalent conductive path, electromagnetic coupling strength, or local impedance between the metal patch radiating structures is changed.

2. The reconfigurable smart metasurface based on phase change materials as described in claim 1, characterized in that: The phase change material is a chalcogenide compound or a chalcogenide compound doped with one or more of the elements Se, Bi, Sn, N, In, Hf, Y, Sc, Ga, and Ti. The chalcogenide compound includes germanium telluride, antimony telluride, and germanium-antimony-telluride.

3. The reconfigurable smart metasurface based on phase change materials as described in claim 1, characterized in that: The first vertical through-hole penetrates the second dielectric layer, and the second vertical through-hole penetrates the second dielectric layer, the intermediate metal layer, and the first dielectric layer. The intermediate metal layer has an insulating clearance area, and the second vertical through-hole passes through the insulating clearance area.

4. The reconfigurable smart metasurface based on phase change materials as described in claim 1, characterized in that: The metal patch radiation structure is one of the following: a bow-shaped patch, a double patch structure, or a multi-region patch topology.

5. The reconfigurable smart metasurface based on phase change materials as described in claim 3, characterized in that: Both the first vertical through hole and the second vertical through hole are filled with one or both of copper and tungsten.

6. The reconfigurable smart metasurface based on phase change materials as described in claim 1, characterized in that: The medium of the first dielectric layer is one of silicon dioxide, silicon nitride, aluminum nitride, and aluminum oxide; the medium of the second dielectric layer includes one of silicon dioxide, silicon nitride, aluminum nitride, and aluminum oxide.

7. The reconfigurable smart metasurface based on phase change materials as described in claim 1, characterized in that: The substrate includes one or more of the following: high-resistivity silicon, diamond, sapphire, silicon carbide, indium phosphide, gallium arsenide, gallium nitride, quartz, and glass.

8. The reconfigurable smart metasurface based on phase change materials as described in claim 1, characterized in that: The intermediate metal layer comprises one or more of gold, copper, silver, aluminum, or platinum.

9. The reconfigurable smart metasurface based on phase change materials as described in claim 1, characterized in that: The contact electrode is composed of one or more of gold, copper, silver, aluminum, and platinum; the metal patch is composed of one or more of gold, copper, silver, aluminum, and platinum.

10. The method for preparing a direct-heating reconfigurable smart metasurface based on phase change materials according to any one of claims 1 to 9, characterized in that: Includes the following steps: S1. Fabricate contact electrodes in the substrate; S2. Deposit a first dielectric layer over the substrate, deposit an intermediate metal layer over the first dielectric layer, and deposit a second dielectric layer over the intermediate metal layer. S3. Prepare a first vertical through-hole and a second vertical through-hole in the first dielectric layer, the intermediate metal layer and the second dielectric layer; S4. Prepare a metal patch on one side of the metal radiation patch structure above the second medium; S5. Deposit a phase change material layer on top of a metal patch on one side of the metal radiation patch structure; S6. Prepare a metal patch on the other side of the metal radiation patch structure above the phase change material layer.

Images