Phase change switch device and preparation method thereof

Abstract

The invention provides a phase change switch device and a preparation method thereof, and belongs to the technical field of microwave switch devices. The phase change switching device comprises a device body and a heat dissipation layer. The upper surface of the device body is provided with a test pressure point and a phase change area. The heat dissipation layer covers the upper surface of the device main body, and the heat dissipation layer is provided with a window capable of exposing the test pressure point. The heat dissipation layer can absorb heat of the phase change area and exchange heat with the surrounding heat exchange medium. The preparation method comprises the following steps: preparing a device main body, and forming a test pressure point on the upper surface of the device main body; preparing a heat dissipation layer on the upper surface of the device main body; and forming a window corresponding to the test pressure point on the heat dissipation layer. According to the invention, the optimization of a heat dissipation path from one direction to three-dimensional is realized, the device obtains a higher switching speed, the bottleneck of the switching speed is solved, and the high-frequency application potential of the device is expanded in performance.

Description

Technical Field

[0001] This application belongs to the field of microwave switching device technology, and more specifically, relates to a phase-change switching device and its fabrication method. Background Technology

[0002] Phase-change switching devices are a new type of semiconductor device that utilizes the significant resistivity difference caused by the reversible phase transition between crystalline and amorphous states of chalcogenide materials (such as Ge2Sb2Te5 and GeTe) to control the on / off state of circuits. Among these, GeTe material exhibits unique potential in radio frequency (RF) and microwave switching applications due to its high crystallization temperature, good thermal stability, and significant resistance contrast. Compared to traditional semiconductor switches (such as PIN diodes) or microelectromechanical systems (MEMS) switches, GeTe-based phase-change switches offer several significant advantages: 1) Extremely high switching resistance ratio: GeTe has a resistivity difference of 3 to 5 orders of magnitude between its amorphous (high resistance) and crystalline (low resistance) states, enabling excellent signal isolation and conduction performance.

[0003] 2) Extremely low RF insertion loss: In crystalline (conduction) state, its resistance is extremely low, resulting in minimal attenuation of high-frequency signals.

[0004] 3) Zero static power consumption: The device does not require an external bias voltage while maintaining any state, and only requires a short pulse of energy when switching states.

[0005] 4) Excellent integrability: Its fabrication process is compatible with mainstream semiconductor planar processes, making it easy to achieve high-density integration and build multifunctional monolithic microwave integrated circuits (MMICs).

[0006] A typical GeTe RF switch employs a four-port structure. Its operating principle is as follows: applying a brief electrical pulse to the heater generates Joule heating, locally raising the temperature of the GeTe phase change material above. When the temperature exceeds its crystallization temperature and is maintained for a sufficient time, GeTe transforms into a low-resistivity crystalline state, and the switch "closes." Applying a shorter, stronger pulse causes the temperature to exceed its melting temperature and then rapidly quenches, transforming GeTe into a high-resistivity amorphous state, and the switch "opens."

[0007] However, although phase-change switching devices typically have a fast "disconnect" (crystallization) process (up to hundreds of nanoseconds), their "close" (melting followed by quenching to form an amorphous state) process—that is, the switching speed—is relatively slow, generally on the order of microseconds. Therefore, the switching speed of existing GeTe phase-change switching devices cannot be applied in faster switching scenarios, becoming a key bottleneck restricting their promotion in higher-frequency, faster switching applications (such as high-speed RF switching networks, millimeter-wave beamforming, pulse signal processing, etc.). Summary of the Invention

[0008] The purpose of this application is to provide a phase change switching device and its fabrication method, aiming to solve the problem that the switching speed of existing phase change switching devices based on chalcogenide compound materials is difficult to further improve.

[0009] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application provide a phase-change switching device, comprising: The main body of the device has a test pressure point and a phase transition region on its upper surface; A heat dissipation layer covers the upper surface of the device body, and the heat dissipation layer has a window that can expose the test pressure point; The heat dissipation layer can absorb the heat from the phase change region and exchange heat with the surrounding heat exchange medium.

[0010] The solutions shown in the embodiments of this application, compared with the prior art, can produce the following beneficial effects: Firstly, the heat dissipation layer directly covers the upper surface containing the phase change region, providing an upward heat conduction path for the phase change material. When the heating pulse ends, the heat generated in the phase change region can not only be dissipated through the substrate below, but also rapidly diffuse to the surrounding heat exchange medium (such as air or the packaging shell) through this heat dissipation layer.

[0011] The transition of a device from "off" to "on" depends on the rapid quenching of a phase change material from a molten state to an amorphous state. The introduction of a heat dissipation layer greatly increases the quenching rate, thereby significantly shortening the switching time of this process and thus greatly reducing the "on" time.

[0012] Although the “shutdown” (crystallization) process itself is relatively fast, more efficient heat dissipation also helps the device return to thermal equilibrium more quickly after multiple cycles, preparing it for the next high-speed switching, which may further increase the limit of repeated switching frequency and thus optimize the “shutdown” time.

[0013] By optimizing the synchronization of "on" and "off" times, the switching time of the device is directly shortened, significantly improving the switching speed.

[0014] Secondly, the increased switching speed enables phase-change switching devices to meet the requirements of higher frequency RF signal switching and higher speed digital / analog signal routing. Phase-change switching devices can adapt to higher frequency and faster systems, and their application areas can be further expanded from traditional RF switches, such as to millimeter-wave communication and phased array systems, high-speed reconfigurable antennas, high-speed test instruments and switching equipment, etc.

[0015] Third, top-mounted heat dissipation prevents localized heat accumulation in and around the phase change region, reducing the risk of material degradation, interface reactions, or failure due to overheating. Simultaneously, faster and more thorough thermal cycling helps the phase change material recover more completely after each switch, potentially reducing material fatigue and thus extending device lifespan and improving cycle durability. Furthermore, consistent and rapid heat dissipation contributes to a more stable and repeatable phase change process, thereby improving the consistency and reliability of key parameters such as switching resistance ratio and insertion loss, which is beneficial for stabilizing device performance parameters.

[0016] Fourth, more efficient heat dissipation means that the required heating pulse energy or duration can be reduced to achieve the same phase transition temperature, or a higher switching speed can be obtained with the same power consumption. This provides more room for optimization in system-level low-power design.

[0017] In summary, this application optimizes the heat dissipation path from "unidirectional (downward)" to "three-dimensional (top and bottom coordinated)" by introducing a top-integrated heat dissipation layer with a window. This fundamentally solves the switching speed bottleneck, expands the potential for high-frequency applications, and enhances the robustness of the device. Ultimately, this improves the market competitiveness and application prospects of the phase-change switching device presented in this application.

[0018] In conjunction with the first aspect, in one possible implementation, the device body includes a substrate structure layer, a heating layer, a thermally conductive layer and a phase change layer stacked from bottom to top. The device body also includes a radio frequency transmission line connected to the phase change layer and extending on the upper surface of the thermally conductive layer. The test pressure point is formed on the radio frequency transmission line, and the heat dissipation layer is disposed on the upper surface of the phase change layer and partially overlaps with the radio frequency transmission line to form the window; The phase transition layer forms the phase transition region.

[0019] In some embodiments, the coverage area of ​​the heating layer is smaller than the area of ​​the upper surface of the substrate structure layer; The device body also includes a planarization layer, which covers the exposed areas of the heating layer and the substrate structure layer, and the upper surface of the planarization layer forms a flat interface. The thermally conductive layer is disposed on the connecting surface.

[0020] In some embodiments, the area of ​​the phase change layer is smaller than the area of ​​the heat dissipation layer, and on a reference plane in the vertical direction, the outer periphery of the phase change layer is located within the outer periphery of the heat dissipation layer.

[0021] In conjunction with the first aspect, in one possible implementation, the heat dissipation layer is a thermally conductive dielectric material layer.

[0022] In conjunction with the first aspect, in one possible implementation, the thickness of the heat dissipation layer is 2. ~3 .

[0023] Secondly, embodiments of this application also provide a method for fabricating a phase-change switching device, comprising the following steps: Prepare a device body and form a test pressure point on the upper surface of the device body; A heat dissipation layer is prepared on the upper surface of the device body; A window corresponding to the test pressure point is formed on the heat dissipation layer.

[0024] The solution shown in this application embodiment has the following advantages compared with the prior art: First, this application places the fabrication of the heat dissipation layer as a subsequent process, after the main device body is completed. This minimizes interference and contamination with the earlier critical process steps, ensuring the quality of the core functional layer. Furthermore, all steps used can be implemented using standard processes, eliminating the need to develop special or expensive new equipment. This allows for integration into existing compound semiconductor or MEMS process production lines, reducing technology migration barriers and R&D costs.

[0025] Secondly, since the fabrication of the heat dissipation layer is carried out independently, its process parameters can be optimized independently and specifically for "maximizing thermal conductivity" and "minimizing interfacial thermal resistance" without having to compromise on the impact on the underlying sensitive functional layers (such as GeTe). By optimizing the fabrication parameters of the heat dissipation layer, the thermal mismatch stress between the heat dissipation layer and the underlying material can be effectively managed, reducing the risk of film cracking or interfacial delamination caused by stress, thereby improving product yield and lifespan.

[0026] Third, the preparation method of this application has clear steps, logically following the principle of "building functionality" followed by "enhancing performance." The process flow design is simple, reducing the complexity and risk of the overall process development. Furthermore, since the core functional components are essentially completed and can undergo intermediate testing before the heat dissipation layer is added, early screening and problem localization are facilitated. The added heat dissipation layer process is mature and independent, and its yield is easily guaranteed, thus contributing to improving the overall yield of the final product and controlling costs. In addition, the post-processing addition mode allows for flexible adjustment of the heat dissipation layer's material, thickness, or pattern without altering the core component design, providing a convenient way to differentiate products for different performance levels or application requirements.

[0027] In conjunction with the second aspect, in one possible implementation, the heat dissipation layer is an aluminum nitride material layer, and the steps for preparing the heat dissipation layer include: Under a first preset condition, an aluminum nitride stress-relief material layer is sputtered onto the upper surface of the device body at a first sputtering power; Under the second preset conditions, an aluminum nitride top material layer is formed by sputtering the aluminum nitride stress buffer material layer onto the upper surface of the aluminum nitride stress buffer material layer with a second sputtering power. The aluminum nitride stress buffer material layer and the aluminum nitride top material layer together form an aluminum nitride prefabricated material layer. Wherein, the second sputtering power is greater than the first sputtering power.

[0028] In some embodiments, the thickness ratio of the aluminum nitride stress-relief material layer to the aluminum nitride top material layer is 1:5 to 2:5.

[0029] In some embodiments, after forming the aluminum nitride preform material layer, the method further includes: The aluminum nitride prefabricated material layer is annealed under a third preset adjustment to obtain an aluminum nitride annealed material layer, which is the heat dissipation layer. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 Schematic diagram of the fabrication process of the phase change switching device provided in Embodiment 1 of this application Figure 1 ; Figure 2 Schematic diagram of the fabrication process of the phase change switching device provided in Embodiment 1 of this application Figure 2 ; Figure 3 Schematic diagram of the fabrication process of the phase change switching device provided in Embodiment 1 of this application Figure 3 ; Figure 4 Schematic diagram of the fabrication process of the phase change switching device provided in Embodiment 1 of this application Figure 4 ; Figure 5 Schematic diagram of the fabrication process of the phase change switching device provided in Embodiment 1 of this application Figure 5 ; Figure 6 Schematic diagram of the fabrication process of the phase change switching device provided in Embodiment 1 of this application Figure 6 ; Figure 7 Schematic diagram of the fabrication process of the phase change switching device provided in Embodiment 1 of this application Figure 7 ; Figure 8 This is a top view of the phase change switching device provided in Embodiment 2 of this application.

[0032] In the figure: 100, device body; 101, test pressure point; 102, phase change region; 110, substrate structure layer; 111, substrate layer; 112, isolation layer; 120, heating layer; 130, thermally conductive layer; 140, phase change layer; 150, radio frequency transmission line; 160, planarization layer; 161, interface surface; 170, thermal control line; 200, heat dissipation layer; 300, window. Detailed Implementation

[0033] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0034] It should be noted that when an element is referred to as being "set on" another element, it can be directly on or indirectly on that other element. It should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0035] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a few" means two or more, unless otherwise explicitly specified.

[0036] Phase change switching devices typically operate quickly during the "opening" (crystallization) process (up to hundreds of nanoseconds), but their "closing" (melting followed by quenching to form an amorphous state) process—that is, the switching speed—is relatively slow, generally on the order of microseconds. This speed bottleneck mainly stems from the limitations imposed by the thermal diffusion kinetics of phase change materials. The "on" process requires the heater to provide sufficient heat to melt the phase change material. The heat must then dissipate through pathways such as the underlying substrate to achieve rapid quenching of the melt and solidification of the amorphous state. The cooling rate of this process directly determines the formation rate of the amorphous phase and the "on" speed. In traditional structures, heat dissipation mainly relies on longitudinal conduction to the substrate. Due to the presence of multiple dielectric layers beneath the phase change material and the thermal resistance of the substrate itself, the heat dissipation path is long and the heat capacity is large, limiting the quenching rate. Furthermore, the upper surface of the device is usually exposed to air or only covered with a passivation layer, resulting in weak lateral heat dissipation capacity, further restricting the overall heat dissipation efficiency.

[0037] The switching speed, especially the "on" speed, of existing phase-change switching devices has become a key bottleneck restricting their widespread adoption in higher-frequency, faster-switching applications (such as high-speed RF switching networks, millimeter-wave beamforming, and pulse signal processing). Although existing technologies have attempted to improve heat dissipation by optimizing heater patterns and using substrates with higher thermal conductivity (such as SiC), the effects are limited and may lead to increased process complexity or higher costs.

[0038] To resolve the above issues, please refer to the following: Figures 1 to 8 The phase-change switching device provided in this application will now be described. The phase-change switching device includes a device body 100 and a heat dissipation layer 200. The upper surface of the device body 100 has a test pressure point 101 and a phase-change region 102; the heat dissipation layer 200 covers the upper surface of the device body 100 and has a window 300 that exposes the test pressure point 101. The heat dissipation layer 200 can absorb heat from the phase-change region 102 and exchange heat with the surrounding heat exchange medium.

[0039] In this embodiment, the heat exchange scheme between the heat dissipation layer 200 and the surrounding heat exchange medium is as follows: 1) The heat dissipation layer 200 is surrounded by air, so the heat dissipation layer 200 exchanges heat with the air; 2) The upper surface of the heat dissipation layer 200 is also connected to the equipment shell, and the heat of the heat dissipation layer 200 can be transferred to the outside through the equipment shell.

[0040] In this embodiment, the window 300 can be a blank area opened in the middle of the heat dissipation layer 200, such as... Figure 7 As shown in window 300. Alternatively, the heat dissipation layer 200 can be set to a smaller overall area, leaving a large empty area around it, which also forms window 300, as shown in the example. Figure 8 As shown.

[0041] The phase-change switching device provided in this application has the following advantages compared with the prior art: Firstly, the heat dissipation layer 200 directly covers the upper surface containing the phase change region 102, providing an upward heat conduction path for the phase change material. When the heating pulse ends, the heat generated by the phase change region 102 can not only be dissipated through the substrate below, but also rapidly diffuse to the surrounding heat exchange medium (such as air or the packaging shell) through the heat dissipation layer 200.

[0042] The device's transition from "off" to "on" depends on the rapid quenching of the phase change material from a molten state to an amorphous state. The introduction of the heat dissipation layer 200 greatly improves the quenching rate, thereby significantly shortening the switching time of this process and thus greatly reducing the "on" time.

[0043] Although the “shutdown” (crystallization) process itself is relatively fast, more efficient heat dissipation also helps the device return to thermal equilibrium more quickly after multiple cycles, preparing it for the next high-speed switching, which may further increase the limit of repeated switching frequency and thus optimize the “shutdown” time.

[0044] By optimizing the synchronization of "on" and "off" times, the switching time of the device is directly shortened, significantly improving the switching speed.

[0045] Secondly, the increased switching speed enables phase-change switching devices to meet the requirements of higher frequency RF signal switching and higher speed digital / analog signal routing. Phase-change switching devices can adapt to higher frequency and faster systems, and their application areas can be further expanded from traditional RF switches, such as to millimeter-wave communication and phased array systems, high-speed reconfigurable antennas, high-speed test instruments and switching equipment, etc.

[0046] Third, top heat dissipation prevents localized heat accumulation in and around the phase change region 102, reducing the risk of material degradation, interface reactions, or failure due to overheating. Simultaneously, faster and more thorough thermal cycling helps the phase change material recover more completely after each switch, potentially reducing material fatigue and thus extending device lifespan and improving cycle durability. Furthermore, consistent and rapid heat dissipation contributes to a more stable and repeatable phase change process, thereby improving the consistency and reliability of key parameters such as switching resistance ratio and insertion loss, which is beneficial for stabilizing device performance parameters.

[0047] Fourth, more efficient heat dissipation means that the required heating pulse energy or duration can be reduced to achieve the same phase transition temperature, or a higher switching speed can be obtained with the same power consumption. This provides more room for optimization in system-level low-power design.

[0048] In summary, this application optimizes the heat dissipation path from "unidirectional (downward)" to "three-dimensional (top and bottom coordinated)" by introducing a top-integrated heat dissipation layer 200 with a window 300. This fundamentally solves the switching speed bottleneck, expands the potential for high-frequency applications, and enhances the robustness of the device. Ultimately, this improves the market competitiveness and application prospects of the phase-change switching device presented in this application.

[0049] In some embodiments, see Figures 6 to 8 The device body 100 includes a substrate structure layer 110, a heating layer 120, a thermally conductive layer 130, and a phase change layer 140 stacked from bottom to top, wherein the phase change layer 140 forms a phase change region 102. The device body 100 also includes a radio frequency transmission line 150, which is connected to the phase change layer 140 and extends on the upper surface of the thermally conductive layer 130. A test pressure point 101 is formed on the radio frequency transmission line 150, and a heat dissipation layer 200 is disposed on the upper surface of the phase change layer 140 and partially overlaps with the radio frequency transmission line 150 to form a window 300.

[0050] In this embodiment, the heat dissipation layer 200 can not only absorb the heat of the phase change layer 140, but also serve as an additional passivation protection layer to protect the underlying delicate structure from environmental (humidity, pollution) effects, thereby further enhancing the environmental reliability of the device.

[0051] This embodiment also clarifies the vertical stacking sequence of "substrate structure layer 110 - heating layer 120 - thermally conductive layer 130 - phase change layer 140 - heat dissipation layer 200". This ensures that heat is generated in the heating layer 120, absorbed by the phase change layer 140, and then rapidly carried away by the top heat dissipation layer 200, forming a highly efficient top-down thermal management path. It achieves tight coupling between the heat source and the heat sink: because the heat dissipation layer 200 is in direct contact with the phase change layer 140, the interfacial thermal resistance is minimized, ensuring that heat can be extracted most efficiently. Simultaneously, since the thermally conductive layer 130 is located between the heating layer 120 and the phase change layer 140, it not only helps to uniformly and quickly guide the heat from the heating layer 120 to the phase change layer 140, but also, to a certain extent, prevents heat from diffusing downwards to the substrate structure layer 110, thus avoiding waste and overheating.

[0052] Furthermore, since the signal passes through the phase change layer 140 (whose resistance determines on / off state) and is transmitted via the RF transmission line 150 above it, placing the transmission line above the thermally conductive layer 130 shortens the interconnection distance with the phase change layer 140, which helps reduce parasitic inductance and resistance, and lowers RF insertion loss. Based on this, the heat dissipation layer 200 can continuously cover a large area to achieve optimal heat dissipation, while precise windowing does not obstruct electrical testing and wire bonding, avoiding potential increases in contact resistance or reliability issues caused by heat dissipation material covering the pressure points.

[0053] Optionally, the heating layer 120 can be implemented using, but is not limited to, a tungsten metal layer, a titanium nitride layer, etc. The heating layer 120 has high thermal conductivity and high stability, as well as good interface stability and controllable resistance, making it an ideal choice for achieving fast, efficient, and reliable thermal pulses. It is especially suitable for scenarios with high requirements for switching speed and durability, and is beneficial for ensuring the reliability of devices and the consistency of electrical performance under long-term high-temperature cycling.

[0054] Optionally, the phase change layer 140 is a chalcogenide compound material, and specific implementation methods include but are not limited to Ge2Sb2Te5 and GeTe.

[0055] Optionally, the thermally conductive layer 130 is a thermally conductive dielectric material layer (e.g., an aluminum nitride layer), which can rapidly and uniformly diffuse the heat generated by the heating layer 120 laterally and efficiently transfer it vertically upward to the entire phase change region 102, ensuring a rapid and uniform phase change process. It also completely isolates the bottom heating layer 120 from the upper phase change layer 140 and the RF transmission line 150 electrically, preventing short circuits or leakage. Furthermore, the thermally conductive layer 130 can withstand repeated high-temperature shocks from heating pulses without reacting or interdiffusion with the materials of the upper and lower heating layers 120 and phase change layers 140, ensuring long-term interface stability. Its coefficient of thermal expansion is as close as possible to that of adjacent materials to reduce thermal stress generated during thermal cycling and prevent film cracking or interface delamination. Moreover, it can be deposited with high quality using standard semiconductor processes (such as sputtering) and is easy to patterned.

[0056] In some embodiments, the area of ​​the heating layer 120 is smaller than the area of ​​the phase change layer 140, and the outer periphery of the heating layer 120 lies within the outer periphery of the phase change layer 140 on a reference plane in the vertical direction. Preferably, the heating layer 120 corresponds to the center position of the phase change layer 140.

[0057] The smaller heating layer 120 ensures that the generated Joule heat is concentrated in the core region directly beneath the phase change layer 140, rather than at the edges. This reduces heat loss due to diffusion into non-functional areas, allowing thermal energy to be used more efficiently to trigger the phase change in the target region, reducing heat loss, and preventing incomplete phase change.

[0058] With the same material and thickness, reducing the area of ​​the heating layer 120 means increasing its resistance. Without changing the material, the resistance of the heater can be optimized more flexibly to match the voltage / current output characteristics of the external drive circuit, thus achieving more efficient pulse drive.

[0059] In the embodiment where the first type of phase change layer 140 is adapted to the heat dissipation layer 200, the area of ​​the phase change layer 140 is equal to the area of ​​the heat dissipation layer 200, and the outer periphery contour of the phase change layer 140 coincides with the outer periphery contour of the heat dissipation layer 200 on the reference plane in the vertical direction.

[0060] The heat generated by the phase change layer 140 can be absorbed by the heat dissipation layer 200 without any leakage, avoiding local heat accumulation or uneven heat dissipation caused by incomplete coverage of the heat dissipation layer 200. At the same time, it also prevents material waste and heat diversion caused by the heat dissipation layer 200 covering the non-phase change region 102, so that all heat dissipation resources are used for the core heat source, maximizing heat dissipation efficiency and further improving the switching speed.

[0061] Complete coverage also ensures a consistent heat conduction path from any point in the phase change layer 140 to the heat dissipation layer 200, reducing lateral thermal diffusion differences caused by misalignment of the heat dissipation layer 200 boundaries. This helps achieve synchronicity and uniformity of temperature changes throughout the entire phase change region 102, making the phase change process more consistent and improving the repeatability and stability of switching characteristics.

[0062] In an embodiment where the second type of phase change layer 140 is adapted to the heat dissipation layer 200, see [reference needed]. Figure 7 and Figure 8 The area of ​​the phase change layer 140 is smaller than the area of ​​the heat dissipation layer 200, and on the reference plane in the vertical direction, the outer periphery of the phase change layer 140 is located within the outer periphery of the heat dissipation layer 200.

[0063] In this embodiment, the heat dissipation layer 200 protruding from the phase change layer 140 forms a heat dissipation buffer zone around the phase change layer 140. When heat is conducted from the phase change layer 140 to the heat dissipation layer 200, it can not only dissipate upwards but also diffuse laterally over a larger area. This increases the contact area and heat capacity with the surrounding heat exchange medium (such as air), thereby further accelerating the cooling rate of the overall structure. This is particularly advantageous for the "on" process, which requires extremely rapid quenching to form an amorphous state, enabling faster switching speeds.

[0064] Meanwhile, the phase change material undergoes a significant volume change during the transition from crystalline to amorphous state (typically, the amorphous state has a lower density). The heat dissipation layer 200 protrudes from the phase change layer 140, providing physical constraint and support to the edge of the phase change layer 140. This effectively suppresses the lateral expansion or contraction of the phase change material during cycling, reducing the resulting interfacial shear stress, thereby significantly reducing the risk of thin film cracking, delamination, or fatigue failure, and significantly extending the device's cycle life.

[0065] Furthermore, this design relaxes the alignment accuracy requirements between the heat dissipation layer 200 and the phase change layer 140. As long as the pattern of the heat dissipation layer 200 completely covers the pattern of the phase change layer 140, strict edge alignment is not required. This reduces the difficulty of the photolithography process and the alignment accuracy requirements, improves the process window 300 and manufacturing yield, and is beneficial for mass production.

[0066] In both of the above embodiments, the heat dissipation layer 200 completely covers the phase change layer 140. In the third embodiment where the phase change layer 140 and the heat dissipation layer 200 are adapted, on the reference plane in the vertical direction, the outer periphery of the phase change layer 140 partially overlaps with the outer periphery of the heat dissipation layer 200, and the heat dissipation layer 200 does not completely cover the phase change layer 140. In this embodiment, the area of ​​the heat dissipation layer 200 is not less than the area of ​​the phase change layer 140, and the portion of the heat dissipation layer 200 protruding from the phase change layer 140 is connected to the upper surface of the thermally conductive layer 130 and / or the radio frequency transmission line 150.

[0067] In some embodiments, see Figure 7 and Figure 8 The radio frequency transmission line 150 extends to the upper surface of the phase change layer 140. The heat dissipation layer 200 covers not only the phase change layer 140 but also part of the radio frequency transmission line 150. Because the heat dissipation layer 200 has a high dielectric constant and high thermal conductivity, it can play a certain role in electromagnetic field localization and shielding on the side of the transmission line, which can potentially help reduce crosstalk and improve high-frequency performance.

[0068] In some embodiments, the heat dissipation layer 200 is a thermally conductive dielectric material layer, such as an aluminum nitride layer or a silicon nitride layer.

[0069] The heat dissipation layer 200 directly covers the upper surface containing the RF transmission line 150 and the phase change layer 140. If the heat dissipation layer 200 is a conductive material, it will cause a direct short circuit to all circuit nodes under the covered area, resulting in complete device failure. Thermally conductive dielectric materials have high resistivity, which ensures electrical insulation between circuit nodes and is a prerequisite for normal device operation.

[0070] Thermally conductive dielectric thin films can be prepared using standard sputtering or chemical vapor deposition processes, making them fully compatible with semiconductor production lines. Their deposition and patterning (etching and windowing) processes are mature and easy to implement.

[0071] Furthermore, the heat dissipation layer 200 serves as the final passivation protection layer for the device. It protects the delicate phase change material and metal circuitry beneath from moisture, ion contamination, and mechanical damage, significantly improving the device's environmental reliability and long-term stability. The thermally conductive dielectric material (especially AlN) has a coefficient of thermal expansion that is more compatible with commonly used semiconductor materials (such as Si, SiC, and SiO2), helping to reduce interfacial stress caused by thermal cycling and improving film adhesion and device durability.

[0072] In some embodiments, see Figures 3 to 8The heating layer 120 has a smaller coverage area than the upper surface area of ​​the substrate structure layer 110. The device body 100 also includes a planarization layer 160, which covers the exposed areas of the heating layer 120 and the substrate structure layer 110, and forms a flat interface 161 on the upper surface of the planarization layer 160. The thermally conductive layer 130 is disposed on the interface 161. The planarization layer 160 may be implemented in ways including, but not limited to, a silicon dioxide layer.

[0073] In this embodiment, the area of ​​the heating layer 120 is smaller than the area of ​​the substrate structure layer 110, meaning that the heater pattern is precisely defined within the desired area, rather than covering the entire substrate structure layer 110. This reduces ineffective heating area and heat dissipation, allowing the generated Joule heat energy to act more concentratedly on the target phase change region 102 above, thereby improving heating efficiency and reducing overall power consumption.

[0074] The introduction of the heating layer 120 creates raised steps on the surface of the substrate structure layer 110. The planarization layer 160 completely fills the sidewalls of the heating layer 120 and covers the exposed area of ​​the substrate structure layer 110, forming a highly flat and continuous interface 161. This provides an ideal stepless surface for the subsequent deposition of the thermally conductive layer 130. This avoids thinning, cracks, or high-stress areas in the thermally conductive layer 130 that may occur at the steps due to uneven coverage, ensuring that the thickness and quality of the thermally conductive layer 130 are uniform in the horizontal direction. This is a key structural guarantee for achieving efficient and uniform heat conduction.

[0075] In some embodiments, the thickness of the heat dissipation layer 200 is 2. ~3 For example, 2.5 .

[0076] By appropriately setting the thickness of the heat dissipation layer 200, it is made to have a considerable heat capacity, enabling it to absorb and temporarily store instantaneous heat from the phase change layer 140, thus preventing heat accumulation. ~3 The thickness is sufficient to create a low thermal resistance channel in the vertical direction, ensuring that heat can be efficiently conducted from the phase change layer 140 to the device surface and exchanged with the environment. If the thickness is too thin, the thermal resistance will increase, and the heat dissipation effect will be greatly reduced.

[0077] As a cover layer, the heat dissipation layer 200, with an appropriate thickness, helps buffer and disperse interfacial stress caused by differences in thermal expansion coefficients. If the thickness is too thin, it may easily crack due to stress; if it is too thick, the self-stress will be too great, easily leading to warping or peeling. 2 ~3 The thickness can be within the empirical range that can better balance stress.

[0078] In addition, 2 ~3 The thickness is suitable for conventional dry or wet etching processes to form windows 300 that expose metal pressure points. The etching process can complete pattern transfer with good anisotropy and selectivity, ensuring that the sidewalls of window 300 are steep and do not damage the underlying metal pressure points. Too thin a thickness is not conducive to etching process control; too thick a thickness will result in excessive etching time, which may lead to critical dimension shifts or deterioration of sidewall morphology.

[0079] In some embodiments, see Figures 5 to 8 The area of ​​the phase change layer 140 is smaller than the area of ​​the heat-conducting layer 130, and on a reference plane in the vertical direction, the outer periphery of the phase change layer 140 is located within the outer periphery of the heat-conducting layer 130. Preferably, the phase change layer 140 is located in the central region of the heat-conducting layer 130.

[0080] The thermally conductive layer 130 has a larger area than the phase change layer 140, meaning that there is a larger high thermal conductivity platform beneath the phase change layer 140. The heat generated by the heating layer 120 is first transferred to the entire plane of the thermally conductive layer 130 for rapid lateral diffusion and homogenization, and then transferred upwards to the relatively smaller area of ​​the phase change layer 140. This ensures that heat can act uniformly and synchronously throughout the entire phase change region 102, avoiding inconsistent phase change states or localized overheating caused by uneven heating, thereby improving the uniformity and repeatability of switching operations.

[0081] Meanwhile, the phase change material undergoes volume change during the transition from crystalline to amorphous state. The larger, more mechanically strong thermally conductive layer 130, serving as a fully covered support substrate, effectively constrains the lateral deformation of the phase change layer 140 and disperses and absorbs the stress generated by the phase change. This reduces the risk of fatigue, cracking, or detachment from the upper and lower layers caused by cyclic stress in the phase change layer 140, significantly improving the device's cycle life and long-term reliability.

[0082] Furthermore, this design forms a synergistic sandwich-style thermal management structure with the aforementioned scheme: the bottom (heating layer 120 < phase change layer 140) enables precise heat injection; the middle (thermal conductive layer 130 > phase change layer 140) achieves lateral heat homogenization and efficient vertical heat transfer; and the top (heat dissipation layer 200 covering phase change layer 140) enables rapid heat dissipation. This synergistic design ensures that the entire path from heat generation and conduction to dissipation is optimized, which is key to achieving ultra-high speed, high uniformity, and high reliability phase change switching.

[0083] It should be noted that the contact area between the heat dissipation layer 200 and the heat-conducting layer 130 should be kept small, or there should be no contact between them, to avoid affecting the heat transfer efficiency of the heating layer 120 to the phase change layer 140. Figure 7 shows a scheme where the heat dissipation layer 200 and the heat-conducting layer 130 have no contact. Figure 8This illustrates a scheme where the heat dissipation layer 200 and the heat conduction layer 130 have a small contact area, specifically, the portion of the heat dissipation layer 200 that protrudes from the phase change layer 140 and the radio frequency transmission line 150 contacts the heat conduction layer 130. To reduce the contact area between the heat conduction layer 130 and the heat dissipation layer 200, the portion of the heat conduction layer 130 that protrudes from the phase change layer 140 can be made smaller.

[0084] Figure 8 The diagram also shows that the area of ​​the planarization layer 160 is larger than that of the heat-conducting layer 130 and the heat dissipation layer 200, the area of ​​the heat dissipation layer 200 is larger than that of the heat-conducting layer 130, and the portion protruding from the heat-conducting layer 130 can be connected to the upper surface of the planarization layer 160.

[0085] In some embodiments, see Figures 1 to 8 The substrate structure layer 110 includes a substrate layer 111 and an isolation layer 112 stacked from bottom to top. The heating layer 120 is disposed on the upper surface of the isolation layer 112. The isolation layer 112 is a thermally conductive dielectric material layer (e.g., an aluminum nitride layer).

[0086] The heating layer 120 must achieve absolute electrical isolation from the conductive or semi-conductive substrate layer 111 (such as SiC, high-resistivity Si) to prevent short circuits. The thermally conductive dielectric material layer simultaneously satisfies both the requirements of "thermal conduction" and "insulation." This ensures the independence and safety of the heater's electrical functions, which is the foundation for the normal operation of the device.

[0087] For radio frequency (RF) devices, substrate 111 is often required as a ground reference plane. High-quality dielectric isolation layer 112 provides stable capacitance characteristics, which helps with impedance control and signal integrity of RF transmission line 150, while reducing losses introduced by the substrate.

[0088] In some embodiments, see Figure 8 The device body 100 also includes a heating control line 170, which is connected to the heating layer 120 and extends on the upper surface of the substrate structure layer 110. In this embodiment, the device body 100 has four ports. Two of these ports are formed by the radio frequency transmission line 150, which is connected to an external signal transmission line and used to control signal on / off. The other two ports, formed by the heating control line 170, are connected to an external power supply line and used to control the power supply to the heating layer 120.

[0089] Based on the same inventive concept, this application also provides a method for fabricating a phase-change switching device, comprising the following steps: A device body 100 is fabricated, and a test pressure point 101 is formed on the upper surface of the device body 100; A heat dissipation layer 200 is prepared on the upper surface of the device body 100; A window 300 corresponding to the test pressure point 101 is formed on the heat dissipation layer 200.

[0090] The method for fabricating the phase-change switching device provided in this application has the following advantages compared with the prior art: First, this application places the fabrication of the heat dissipation layer 200 as a subsequent process, after the completion of the entire device body 100. This minimizes interference and contamination with the earlier key process steps, ensuring the quality of the core functional layer. Furthermore, all steps used can be implemented using standard processes, eliminating the need to develop special or expensive new equipment. This allows for integration into existing compound semiconductor or MEMS process production lines, reducing technology migration barriers and R&D costs.

[0091] Secondly, since the fabrication of the heat dissipation layer 200 is carried out independently, its process parameters can be optimized independently and specifically for "maximizing thermal conductivity" and "minimizing interfacial thermal resistance" without having to compromise on the impact on the underlying sensitive functional layer (such as GeTe). By optimizing the fabrication parameters of the heat dissipation layer 200, the thermal mismatch stress between the heat dissipation layer 200 and the underlying material can be effectively managed, reducing the risk of film cracking or interfacial delamination caused by stress, thereby improving product yield and lifespan.

[0092] Third, the preparation method of this application has clear steps, logically following the principle of "building functionality" followed by "enhancing performance." The process flow design is simple, reducing the complexity and risk of the overall process development. Furthermore, since the core functional components are essentially completed and can undergo intermediate testing before the addition of the heat dissipation layer 200, early screening and problem localization are facilitated. The added heat dissipation layer 200 has a mature and independent process, and its yield is easily guaranteed, thus contributing to improved overall product yield and cost control. In addition, the post-processing addition mode allows for flexible adjustment of the material, thickness, or pattern of the heat dissipation layer 200 without altering the core component design, providing a convenient way to differentiate products for different performance levels or application requirements.

[0093] In some embodiments, the heat dissipation layer 200 is an aluminum nitride material layer, and the steps for preparing the heat dissipation layer 200 include: Under the first preset conditions, an aluminum nitride stress-relief material layer is sputtered onto the upper surface of the device body 100 at a first sputtering power; Under the second preset conditions, an aluminum nitride top material layer is formed by sputtering an aluminum nitride stress buffer material layer onto the upper surface of the aluminum nitride stress buffer material layer with a second sputtering power. The aluminum nitride stress buffer material layer and the aluminum nitride top material layer together form an aluminum nitride prefabricated material layer. The second sputtering power is greater than the first sputtering power.

[0094] Optionally, the first sputtering power is 1600W~1800W (e.g., 1650W, 1700W, 1750W), and the second sputtering power is 2400W~2700W (e.g., 2450W, 2500W, 2600W).

[0095] Low-power sputtering easily forms polycrystalline layers and can relax interfacial stress, but the crystal quality is poor and the presence of many defects will exacerbate phonon scattering and reduce thermal conductivity. High power can improve the mobility of Al atoms, allowing atoms to form bonds in an orderly manner, reducing defects and optimizing crystal quality, and facilitating heat dissipation. However, excessive power can easily lead to target poisoning and damage the film quality.

[0096] In this embodiment, the aluminum nitride stress-relief material layer formed with low power helps relax interfacial stress and form crystal nuclei, but may have more defects. Subsequently, the top aluminum nitride material layer is deposited with higher power (second sputtering power), which provides higher atomic migration energy, promotes ordered atomic arrangement, and reduces lattice defects and grain boundaries. This combined effect significantly improves the overall crystallinity and density of the AlN film, thereby maximizing its thermal conductivity, which is the direct material basis for achieving high-speed heat dissipation.

[0097] The heat dissipation layer 200 has a different coefficient of thermal expansion than the underlying multilayer materials (RF transmission line 150, phase change layer 140, and thermally conductive layer 130). Directly sputtering a thick aluminum nitride layer at high power onto the already completed device surface may cause the film to crack or peel off from the interface due to the huge internal stress. Depositing a buffer layer at low power first can more gently adapt to the interface, effectively relax and buffer most of the stress, and provide a stable substrate for the subsequent growth of high-quality thick layers.

[0098] This embodiment, through an optimized two-step process, especially through a first-layer buffer to achieve better interface bonding, can significantly improve the adhesion strength between the entire heat dissipation layer 200 and the device body 100, ensuring interface stability during thermal cycling and improving the long-term operational reliability of the device.

[0099] In some embodiments, the first preset conditions include a first substrate temperature, a first Ar:N2 volumetric flow rate ratio, and a first working gas pressure, and the second preset conditions include a second substrate temperature, a second Ar:N2 volumetric flow rate ratio, and a second working gas pressure. Specifically, the first substrate temperature is lower than the second substrate temperature, the proportion of nitrogen in the first Ar:N2 volumetric flow rate ratio is lower than the proportion of nitrogen in the second Ar:N2 volumetric flow rate ratio, and the first working gas pressure is higher than the second working gas pressure.

[0100] Optionally, the first substrate temperature is 450℃~500℃ (e.g., 470℃, 480℃, 490℃), and the second substrate temperature is 680℃~700℃ (e.g., 685℃, 690℃, 695℃). The first Ar:N2 volumetric flow rate ratio is 1:4~1:6 (e.g., 1:5, 1:5.5), and the second Ar:N2 volumetric flow rate ratio is 1:6~1:10 (e.g., 1:7, 1:8, 1:9). The first working gas pressure is 5mtorr~7mtorr (e.g., 5.5mtorr, 6mtorr), and the second working gas pressure is 2.8mtorr~3.2mtorr (e.g., 2.9mtorr, 3.1mtorr).

[0101] When the Ar:N2 volumetric flow rate ratio is below 35%, single-phase AlN formation is difficult, resulting in insufficient bonding and numerous defects. A suitable ratio can promote the formation of hexagonal AlN. Excessively high working pressure increases atomic collisions, disrupting crystal arrangement; excessively low pressure may lead to uneven deposition, both affecting heat dissipation. At excessively low temperatures, Al atoms lack sufficient energy, resulting in poor crystal quality. Appropriate heating can promote atomic diffusion and crystallization, reducing defects and improving thermal conductivity; however, excessively high temperatures may damage the substrate and exacerbate thermal mismatch, leading to stress defects.

[0102] In some embodiments, the thickness ratio of the aluminum nitride stress-relief material layer to the aluminum nitride top material layer is 1:5 to 2:5 (e.g., 1:4.5, 1:3.5).

[0103] If the aluminum nitride stress buffer material layer is too thin (<1:5), it will be difficult to fully relax the interfacial stress, which may lead to excessive stress accumulation during the growth of the top layer, easily causing the film to crack or peel off from the interface.

[0104] While a thicker aluminum nitride stress-relief layer (>2:5) provides better stress buffering, it typically results in poorer crystal quality and lower thermal conductivity. An excessively thick aluminum nitride stress-relief layer significantly increases the overall thermal resistance of the heat dissipation layer, weakening its heat dissipation effect. It also adds unnecessary processing time.

[0105] Within a ratio range of 1:5 to 2:5, the aluminum nitride stress-relief material layer is sufficient to effectively bear and relax most of the interfacial stress, providing a stable substrate for high-quality growth of the top layer. At the same time, its thickness ratio does not significantly drag down the overall thermal conductivity, achieving the best balance between stress control and thermal performance.

[0106] The aluminum nitride top layer is deposited at higher power to achieve high crystallinity and high thermal conductivity. A 1:5 to 2:5 ratio ensures that the aluminum nitride top layer occupies the majority of the heat dissipation layer 200 thickness (approximately 71% to 83%). This makes the overall thermal performance of the heat dissipation layer 200 approach that of a high-quality top layer, thereby maximizing its heat dissipation capacity.

[0107] In some embodiments, after forming the aluminum nitride preform layer, the method further includes: The aluminum nitride prefabricated material layer is annealed using the third preset adjustment to obtain an aluminum nitride annealed material layer, which serves as a heat dissipation layer.

[0108] Although the two-step sputtering method manages interfacial stress through an aluminum nitride stress-reducing material layer, the deposition process itself accumulates intrinsic stress (typically compressive stress) within the film. The annealing process provides additional energy to the atoms in the AlN film, enabling short-range diffusion and rearrangement. This has the following effects: 1) It can repair some lattice defects introduced during sputtering, promote grain coalescence and growth, and reduce grain boundary density. 2) Reducing grain boundaries and defects improves the crystallinity and overall thermal conductivity of the AlN film, thus ensuring its heat dissipation capacity. 3) By reducing the internal stress of the film through atomic rearrangement, a stress-stable heat dissipation layer is obtained, reducing the risk of cracking, warping, or peeling from the underlying layer due to stress release during subsequent processes or long-term use. This is crucial for ensuring the mechanical reliability of the device.

[0109] In some embodiments, the window preparation step includes: A window is formed on the heat dissipation layer using photolithography.

[0110] This embodiment uses photolithography and etching techniques to precisely open windows on the heat dissipation layer, which ensures effective exposure of the test pressure point and achieves reliable electrical connection, while ensuring that the heat dissipation layer maximizes and uniformly covers the phase transition region.

[0111] The specific implementation method of the phase change switching device of this application is illustrated in the following example: S100. The SiC substrate is cleaned using a standard wafer cleaning process, and 1 mol / L is sputtered onto the upper surface of the substrate using a sputtering process. ~4 Aluminum nitride thin film. A photolithography process involving coating, exposure, and development is used to define the isolation region on the substrate. A photoresist mask is then used to etch away the aluminum nitride outside the isolation region. The masking photoresist is then removed to form an aluminum nitride isolation layer on the upper surface of the substrate. Figure 1 As shown.

[0112] S200: A 50nm~300nm W metal layer is sputtered onto the upper surface of the isolation layer. A photolithography process involving coating, exposure, development, and hardening is used to define the heating region. The W metal outside the heating region is then etched clean using a photoresist mask. Finally, the masking photoresist is removed to obtain the heating layer and heating control lines. Figure 2 As shown.

[0113] S300, deposit 1 on the upper surface of the isolation layer, heating layer and heating control line. ~2 The heater is completely covered with silica, and the surface is planarized using a standard silica chemical mechanical polishing process, achieving a surface roughness of approximately 0.5 nm. The final planarization layer is obtained, such as... Figure 3 As shown.

[0114] S400, Sputtering 1 on the planarized upper surface Aluminum nitride thin film is used as a thermally conductive layer. A photolithography process involving coating, exposure, and development is employed to define the thermally conductive area. A photoresist mask is then used to etch away the aluminum nitride outside the thermally conductive area. Finally, the masking photoresist is removed, completing the fabrication of the thermally conductive layer. Figure 4 As shown.

[0115] S500: Define the phase change material region on the thermally conductive layer, and then use magnetron sputtering to sputter 700 on the upper surface of the thermally conductive layer. ~2500 The GeTe material was sputtered. After sputtering, an organic lift-off process (i.e., a double-layer resist lift-off photolithography process) was used to fabricate the phase change layer, such as... Figure 5 As shown.

[0116] S600: The RF transmission line region is defined on the upper surface of the phase change layer and the thermally conductive layer. Then, a 500nm~1000nm Ti / Au metal layer is formed on the upper surface of the phase change layer and the thermally conductive layer using an evaporation process. The transmission line pattern is then stripped using an organic lift-off process to complete the RF transmission line fabrication. Figure 6 As shown.

[0117] S700, sputtering 2 on the upper surface of the phase change layer, thermal conductive layer and RF control line. ~3 Aluminum nitride is fabricated using a photolithography process involving coating, exposure, development, and hardening. The test pressure points are defined, and the silicon nitride on these points is etched away using photoresist as a mask. The masking photoresist is then removed to complete the fabrication of the heat dissipation layer. Figure 7 As shown.

[0118] Step S700 specifically includes: S710 uses an Al target, with the first sputtering power controlled at 1600W~1800W, the first substrate temperature at 450℃~500℃, the first Ar:N2 volumetric flow rate ratio at 1:4~1:6, and the first working gas pressure at 5mtorr~7mtorr. An AlN layer (aluminum nitride stress buffer material layer) with a thickness of 650nm~1000nm is sputtered and deposited on the upper surface of the phase change layer, the thermal conductive layer, and the RF control line.

[0119] S720, adjust the sputtering power to 2400W~2700W (second sputtering power), increase the substrate temperature to 680℃~700℃ (second substrate temperature), adjust the Ar:N2 volume flow rate ratio to 1:6~1:10 (second Ar:N2 volume flow rate ratio), and the working gas pressure to 2.8mtorr~3.2mtorr (second working gas pressure), and deposit a 1500nm~2000nm thick AlN top layer (aluminum nitride top material layer) on the upper surface of the aluminum nitride stress buffer material layer.

[0120] S730. The prepared AlN film (aluminum nitride prefabricated material layer) is subjected to high-temperature annealing to further eliminate residual stress and lattice defects in the film.

[0121] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A phase-change switching device, characterized in that, include: The device body (100) has a test pressure point (101) and a phase transition region (102) on its upper surface; A heat dissipation layer (200) covers the upper surface of the device body (100), and the heat dissipation layer (200) has a window (300) that can expose the test pressure point (101); The heat dissipation layer (200) can absorb the heat of the phase change region (102) and exchange heat with the surrounding heat exchange medium.

2. The phase-change switching device as described in claim 1, characterized in that, The device body (100) includes a substrate structure layer (110), a heating layer (120), a thermally conductive layer (130) and a phase change layer (140) stacked from bottom to top. The device body (100) also includes a radio frequency transmission line (150), which is connected to the phase change layer (140) and extends on the upper surface of the thermally conductive layer (130). The test pressure point (101) is formed on the radio frequency transmission line (150), and the heat dissipation layer (200) is disposed on the upper surface of the phase change layer (140) and partially overlaps with the radio frequency transmission line (150) to form the window (300). The phase change layer (140) forms the phase change region (102).

3. The phase-change switching device as described in claim 2, characterized in that, The coverage area of ​​the heating layer (120) is smaller than the area of ​​the upper surface of the substrate structure layer (110); The device body (100) further includes a planarization layer (160), which covers the exposed areas of the heating layer (120) and the substrate structure layer (110), and the upper surface of the planarization layer (160) forms a flat interface (161). The heat-conducting layer (130) is disposed on the connecting surface (161).

4. The phase-change switching device as described in claim 2, characterized in that, The area of ​​the phase change layer (140) is smaller than the area of ​​the heat dissipation layer (200), and on the reference plane in the vertical direction, the outer periphery of the phase change layer (140) is located within the outer periphery of the heat dissipation layer (200).

5. The phase-change switching device as described in claim 1, characterized in that, The heat dissipation layer (200) is a thermally conductive dielectric material layer.

6. The phase-change switching device as described in claim 1 or 5, characterized in that, The thickness of the heat dissipation layer (200) is 2. ~3 .

7. A method for fabricating a phase-change switching device, characterized in that, Includes the following steps: A device body (100) is prepared, and a test pressure point (101) is formed on the upper surface of the device body (100); A heat dissipation layer (200) is prepared on the upper surface of the device body (100); A window (300) corresponding to the test pressure point (101) is formed on the heat dissipation layer (200).

8. The method for fabricating the phase-change switching device as described in claim 7, characterized in that, The heat dissipation layer (200) is an aluminum nitride material layer, and the steps for preparing the heat dissipation layer (200) include: Under a first preset condition, an aluminum nitride stress-relief material layer is sputtered onto the upper surface of the device body (100) at a first sputtering power; Under the second preset conditions, an aluminum nitride top material layer is formed by sputtering the aluminum nitride stress buffer material layer onto the upper surface of the aluminum nitride stress buffer material layer with a second sputtering power. The aluminum nitride stress buffer material layer and the aluminum nitride top material layer together form an aluminum nitride prefabricated material layer. Wherein, the second sputtering power is greater than the first sputtering power.

9. The method for fabricating the phase-change switching device as described in claim 8, characterized in that, The thickness ratio of the aluminum nitride stress-relief material layer to the aluminum nitride top material layer is 1:5 to 2:

5.

10. The method for fabricating the phase-change switching device as described in claim 8, characterized in that, After forming the aluminum nitride preform material layer, the process further includes: The aluminum nitride prefabricated material layer is annealed with a third preset adjustment to obtain an aluminum nitride annealed material layer, which is the heat dissipation layer (200).

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