MEMS switch, preparation method for MEMS switch, radio frequency front-end device, and electronic device

Abstract

The present application relates to the technical field of switches, and provides an MEMS switch, a preparation method for an MEMS switch, and an electronic device. The MEMS switch comprises a substrate and a capacitor, wherein the capacitor comprises a first electrode, a capacitor layer, and a second electrode, and the first electrode is located in the substrate. The MEMS switch further comprises a contact and a switch structure, wherein at least a portion of the contact protrudes from a surface of the substrate; the contact is connected to the first electrode; the switch structure comprises a fixed part and a cantilever part that are connected; the fixed part is connected to the substrate; the extension direction of the fixed part is perpendicular to the extension direction of the cantilever part; the extension direction of the cantilever part is parallel to the surface of the substrate, the cantilever part extends to a position above the contact, and the cantilever part is configured to be in contact with the contact. The present application comprises the fixed part perpendicular to the surface of the substrate and the cantilever part of which the extension direction is perpendicular to that of the fixed part. Compared with a switch structure having a corner, the present application can avoid sparking between the corner and the capacitor, thereby reducing the current leakage of the switch structure.

Description

MEMS switches, MEMS switch fabrication methods, RF front-end devices, electronic devices

[0001] This application claims priority to Chinese Patent Application No. 202510231377.6, filed on February 27, 2025, entitled "MEMS Switch, Method for Fabricating MEMS Switch, Radio Frequency Front-End Device, Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of switch technology, and in particular to a MEMS switch, a method for fabricating a MEMS switch, and radio frequency front-end devices and electronic devices. Background Technology

[0003] MEMS switches, fabricated using Micro-Electro-Mechanical Systems (MEMS) technology, control the on / off state of signals by manipulating the mechanical movement of a cantilever beam. These switches offer advantages such as low loss, low power consumption, small size, and high linearity, and can be applied in radio frequency systems such as phase shifters, tuned antennas, tunable filters, beamforming, and switch matrices.

[0004] In some existing MEMS switches, when the cantilever beam comes into contact with the capacitor electrodes during operation, the cantilever beam is prone to leakage current and arcing failure due to the large transmission line current, which degrades the performance of the switch. Summary of the Invention

[0005] This application provides a MEMS switch, a method for fabricating the MEMS switch, as well as an RF front-end device and an electronic device. The main objective is to provide a MEMS switch that can reduce leakage current and prevent arcing.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] In one aspect, this application provides a MEMS switch, which, for example, can be used in a radio frequency system.

[0008] The MEMS switch includes a substrate and a capacitor. The capacitor includes a first electrode, a capacitor layer, and a second electrode. The first electrode, capacitor layer, and second electrode are stacked sequentially along the thickness direction of the substrate, and the first electrode is located within the substrate. The MEMS switch also includes a contact and a switching structure. At least a portion of the contact protrudes from the surface of the substrate and is connected to the first electrode. The switching structure is disposed on the substrate and includes a fixed portion and a cantilever portion. The fixed portion is connected to the substrate, and the extension direction of the fixed portion is perpendicular to the extension direction of the cantilever portion. The extension direction of the cantilever portion is parallel to the surface of the substrate, and the cantilever portion extends above the contact and is used to contact the contact.

[0009] In the MEMS switch provided in this application, since the first electrode of the capacitor is disposed in the substrate, that is, at least part of the capacitor is located in the substrate, and a contact connected to the first electrode is provided, the switch structure can be connected to the first electrode to realize the conduction and turn-off of the MEMS switch.

[0010] In some related technologies, the first electrode, capacitor layer, and second electrode are all disposed above a substrate, and the switching structure can directly contact the second electrode located at the top to achieve switching. In these related technologies, because the first electrode, capacitor layer, and second electrode are stacked on the substrate and have a large thickness, the switching structure needs to extend above the second electrode located at the top. This results in a corner in the switching structure that is close to the capacitor, which is prone to arcing. However, in this application, the first electrode of the capacitor, or the first electrode and capacitor layer, or the first electrode, capacitor layer, and second electrode are disposed within the substrate, and a contact connected to the first electrode is provided to contact the switching structure to achieve switching. Because the contact located on the substrate has a significantly compressed thickness compared to the first electrode, capacitor layer, and second electrode stacked on the substrate, the resulting switching structure does not have a corner close to the capacitor. Instead, it includes a fixed portion perpendicular to the substrate surface and a cantilever portion perpendicular to the extension direction of the fixed portion. Compared to the aforementioned prior art with corners, this application can avoid arcing between the corner and the capacitor, thereby reducing the leakage current of the switching structure.

[0011] In addition, since there are no corners in the switch structure of this application example, the strength of the switch structure can be improved, the switching frequency of the switch structure can be increased, and the performance of the switch device can be optimized.

[0012] In one possible implementation, the capacitor layer is located within the substrate, the second electrode is located on the substrate, and the first electrode includes a side portion and a bottom portion, with contacts connected to the side portion.

[0013] In this implementation, the capacitor layer is disposed within the substrate, which allows for a reduction in the overall height of the MEMS switch.

[0014] In one feasible approach, both the capacitor layer and the second electrode are located on the substrate.

[0015] In one possible implementation, the capacitor layer has a first side surface, and the second electrode has a second side surface. Both the first and second sides are close to the switch structure, and the second side surface is farther from the contact than the first side surface.

[0016] Since the second side of the second electrode is further away from the contact than the first side of the capacitor layer, there is space to allow for the setting of the contact; and when the cantilever part comes into contact with the contact, the distance between the cantilever part and the second electrode can be increased to avoid arcing between the cantilever part and the second electrode.

[0017] In one possible implementation, both the capacitor layer and the second electrode are located within a substrate; the substrate has opposing first and second surfaces, and a switching structure is disposed on the first surface; the first electrode includes a side portion and a bottom portion, with contacts connected to the side portion; the bottom portion, the capacitor layer, and the second electrode are disposed from the second surface to the first surface.

[0018] In this example, within the feasible process, the first electrode, capacitor layer, and second electrode can be sequentially deposited within a groove formed in the substrate using a deposition process. The fabrication process is simple and does not pose any challenges to the process.

[0019] In one possible implementation, the second electrode includes a first portion and a second portion, wherein the projection of the first portion onto the first electrode is located within the boundary of the first electrode, and the projection of the second portion onto the first electrode is located outside the boundary of the first electrode; the MEMS switch also includes a first conductive via and a first pad, wherein the first pad is disposed on the surface of the substrate opposite to the switch structure, and the first conductive via penetrates the substrate to connect the second portion and the first pad.

[0020] Since the second electrode needs to be electrically connected to the control circuit, in this implementation structure, the area of ​​the second electrode can be made larger, and the second part located outside the boundary of the first electrode can be electrically connected to the external control circuit. For example, a first conductive via can be opened in the substrate, and the second part can be electrically connected to the external control circuit through the first conductive via and the first pad.

[0021] In one possible implementation, both the capacitor layer and the second electrode are located within a substrate; the substrate has opposing first and second surfaces, and a switching structure is disposed on the first surface; the second electrode, the capacitor layer, and the first electrode are disposed from the second surface to the first surface.

[0022] In this example, within the feasible process, the second electrode, capacitor layer, and first electrode can be sequentially deposited within a groove formed in the substrate using a deposition process. The fabrication process is simple and does not pose any challenges to the process.

[0023] In one possible implementation, the MEMS switch further includes a second conductive via and a second pad, the second pad being disposed on the surface of the substrate opposite to the switch structure, and the second conductive via penetrating the substrate to connect the second electrode and the second pad.

[0024] In this example, since the second electrode is closer to the bottom surface of the substrate (the surface opposite to the switch structure) than the first electrode, a second conductive via can be directly provided below the second electrode. The second electrode is electrically connected to the external control circuit through the second conductive via and the second pad.

[0025] In one possible implementation, the MEMS switch also includes a pull-down electrode located in the space between the cantilever portion and the substrate.

[0026] By setting a pull-down electrode, the pull-down force on the cantilever section can be increased, enabling rapid conduction of the MEMS switch.

[0027] In one possible implementation, the MEMS switch further includes a third conductive via and a third pad, the third pad being disposed on the surface of the substrate opposite to the switch structure, and the third conductive via penetrating the substrate to connect the pull-down electrode and the third pad.

[0028] For example, the pull-down electrode can be connected to the ground terminal via the third conductive via and the third pad.

[0029] In one possible implementation, the MEMS switch further includes a fourth conductive via and a fourth pad, the fourth pad being disposed on the surface of the substrate opposite to the switch structure, and the fourth conductive via penetrating the substrate to connect the fixing portion and the fourth pad.

[0030] For example, the fixed part of the switch structure can be connected to the ground terminal through the fourth conductive through hole and the third pad.

[0031] In one feasible approach, multiple contacts are arranged at intervals along a direction perpendicular to the extension direction of the cantilever portion. By providing multiple contacts, the contact area between the cantilever portion and the contacts can be increased, thereby enhancing the stability of the electrical connection between the cantilever portion and the contacts.

[0032] Secondly, this application provides a radio frequency front-end device, which includes a filter and a MEMS switch implemented in any of the above embodiments, wherein the MEMS switch is electrically connected to the filter.

[0033] Since the RF front-end device provided in this application includes a MEMS switch in any of the above implementations, the MEMS switch will not have a corner that is close to the capacitor, which can avoid arcing between the corner and the capacitor, thereby reducing the leakage current of the switch structure.

[0034] In addition, since there are no corners in the switch structure of this application example, the strength of the switch structure can be improved, the switching frequency of the switch structure can be increased, and the performance of the switch device can be optimized.

[0035] Thirdly, this application provides an electronic device that includes a control circuit and a MEMS switch as described in any of the above implementations, or includes a radio frequency front-end device as described in the above implementations, wherein the control circuit is electrically connected to the MEMS switch.

[0036] Since the electronic device provided in this application includes a MEMS switch in any of the above implementations, in the MEMS switch, since the first electrode of the capacitor is disposed in the substrate, that is, at least part of the capacitor is located in the substrate, and a contact connected to the first electrode is provided, the switch structure can be connected to the first electrode to realize the opening and closing of the MEMS switch. In some related technologies, the first electrode, capacitor layer, and second electrode are all disposed above a substrate, and the switching structure can directly contact the second electrode located at the top to achieve switching. In these related technologies, because the first electrode, capacitor layer, and second electrode are stacked on the substrate and have a large thickness, the switching structure needs to extend above the second electrode located at the top. This results in a corner in the switching structure that is close to the capacitor, which is prone to arcing. However, in this application, the first electrode of the capacitor, or the first electrode and capacitor layer, or the first electrode, capacitor layer, and second electrode are disposed within the substrate, and a contact connected to the first electrode is provided to contact the switching structure to achieve switching. Because the contact located on the substrate has a significantly compressed thickness compared to the first electrode, capacitor layer, and second electrode stacked on the substrate, the resulting switching structure does not have a corner close to the capacitor. Instead, it includes a fixed portion perpendicular to the substrate surface and a cantilever portion perpendicular to the extension direction of the fixed portion. Compared to the aforementioned prior art with corners, this application can avoid arcing between the corner and the capacitor, thereby reducing the leakage current of the switching structure.

[0037] In addition, since there are no corners in the switch structure of this application example, the strength of the switch structure can be improved, the switching frequency of the switch structure can be increased, and the performance of the switch device can be optimized.

[0038] Fourthly, this application provides a method for fabricating a MEMS switch, the method comprising:

[0039] A groove is formed in the substrate;

[0040] A capacitor and a contact are fabricated. The capacitor includes a first electrode, a capacitor layer, and a second electrode. The first electrode, the capacitor layer, and the second electrode are stacked sequentially along the thickness direction of the substrate. The first electrode is located in a groove. At least a portion of the contact protrudes from the surface of the substrate and is connected to the first electrode.

[0041] A sacrificial layer is created, which at least covers the contact point;

[0042] Open windows inside the sacrificial layer;

[0043] A switch structure is obtained, the switch structure includes a fixed part and a cantilever part, at least a portion of the fixed part is located inside the opening, and the cantilever part is located on the sacrificial layer and extends above the contact.

[0044] Remove the sacrificial layer.

[0045] In the fabrication method provided in this application, a groove is formed in the substrate, and at least the first electrode of the capacitor is disposed in the groove. Compared with disposing the first electrode, capacitor layer and second electrode on the substrate, the thickness of the capacitor above the substrate can be reduced. Furthermore, by setting a contact that connects to the first electrode and a contact that cooperates with the cantilever portion of the switch structure, the thickness of the contact is significantly reduced compared with the thickness of stacking the first electrode, capacitor layer and second electrode. Thus, in the resulting switch structure, the extension direction of the fixed portion is perpendicular to the extension direction of the cantilever portion, that is, the fixed portion is perpendicular to the substrate surface, and there will be no corner that is close to the capacitor. This can avoid arcing between the corner and the capacitor, thereby reducing the leakage current of the switch structure.

[0046] In one feasible manner, a first electrode and a capacitor layer are formed in a groove, and a second electrode is formed on a substrate; or, a first electrode is formed in a groove, and a capacitor layer and a second electrode are formed on a substrate; or, a first electrode, a capacitor layer, and a second electrode are formed in a groove.

[0047] In other words, the entire film structure of the capacitor can be placed inside the substrate, or the first electrode and the capacitor layer can be placed inside the substrate.

[0048] In one feasible manner, before forming the sacrificial layer, the fabrication method further includes: forming a pull-down electrode; and creating a window within the sacrificial layer, including: the window being located on the side of the pull-down electrode away from the capacitor.

[0049] By setting a pull-down electrode, the pull-down force on the cantilever can be increased, enabling rapid switching of the switching state of the MEMS switch. Attached Figure Description

[0050] Figure 1 is a schematic diagram of the structure of a base station according to an example of this application;

[0051] Figure 2 is a schematic diagram of the structure of an electronic device according to an example of this application;

[0052] Figure 3 is a schematic diagram of the circuit structure of an electronic device according to an example of this application;

[0053] Figure 4 is a schematic diagram of the circuit structure of an electronic device according to an example of this application;

[0054] Figure 5 is a schematic diagram of a MEMS switch provided in an embodiment of this application;

[0055] Figure 6 is a schematic diagram of the AA cross-sectional view in Figure 5;

[0056] Figure 7 is another schematic diagram of the AA cross-sectional view in Figure 5;

[0057] Figure 8 is a schematic diagram of the BB cross-section of Figure 5;

[0058] Figures 9 to 14 are schematic diagrams of the process structure after each step is completed in the fabrication method of a MEMS switch provided in the embodiments of this application;

[0059] Figure 15 is a schematic diagram of a MEMS switch provided by related technologies;

[0060] Figures 16 to 20 are schematic diagrams of the process structure after each step in a MEMS switch fabrication method provided by related technologies;

[0061] Figure 21 is another schematic diagram of the AA cross-sectional view in Figure 5;

[0062] Figure 22 is another schematic diagram of the BB cross-section of Figure 5;

[0063] Figure 23 is another schematic diagram of the AA cross-sectional view in Figure 5;

[0064] Figure 24 is another schematic diagram of the AA cross-sectional view in Figure 5;

[0065] Figure 25 is another schematic diagram of the AA cross-sectional view in Figure 5;

[0066] Figure 26 is another schematic diagram of the AA cross-sectional view in Figure 5;

[0067] Figure 27 is a top view of a MEMS switch provided in an embodiment of this application;

[0068] Figure 28 is a schematic diagram of a switch structure in a MEMS switch provided in an embodiment of this application;

[0069] Figure 29 is a flowchart of a method for fabricating a MEMS switch according to an embodiment of this application.

[0070] Reference numerals: 100-Circuit board; 200-MEMS switch; 300-Control circuit; 1-Substrate; 2-Capacitor; 3-Switch structure; 4-Contact; 51, 52, 53, 54-Conductive vias; 61, 62, 63, 64-Pads; 7-Pull-down electrode; 81-First conductor; 82-Second conductor; 21-First electrode; 22-Capacitor layer; 23-Second electrode; 31-Fixed portion; 32-Cantilever portion; 211-Side portion; 212-Bottom portion. Detailed Implementation

[0071] The solutions involved in the embodiments of this application will be described below with reference to the accompanying drawings.

[0072] This application provides an electronic device that may include communication devices (e.g., base stations, mobile phones), wireless charging devices, medical devices, radar, navigation devices, radio frequency (RF) plasma lighting devices, RF induction and microwave heating devices, etc. This application does not impose any special limitations on the specific form of the aforementioned electronic device.

[0073] The aforementioned electronic devices generally include radio frequency (RF) semiconductor devices, such as power amplifiers (PAs). The main function of a PA is to amplify RF signals. Taking a base station as an example, Figure 1 shows a simplified structural diagram of a base station. This base station includes a control unit, which comprises a radio transceiver, antennas, and related signal processing circuits. The control unit mainly consists of four components: a cell controller, a voice channel controller, a signaling channel controller, and a multiplexer interface for expansion. The base station control unit typically controls several base station transceivers. Through remote commands from the transceivers and mobile stations, the base station control unit is responsible for managing all mobile communication interfaces, primarily the allocation, release, and management of radio channels.

[0074] Referring back to Figure 1, the base station also includes a transmission unit, which is connected to the core network. Control signaling, voice calls, or data service information from the core network side are sent to the base station's control unit through the transmission unit, and these services are processed by the control unit.

[0075] Referring to Figure 1, the base station also includes a baseband unit and a radio frequency (RF) unit. The baseband unit mainly performs functions such as baseband modulation and demodulation, allocation of radio resources, call processing, power control, and soft handover. The RF unit mainly performs the conversion between the air radio frequency channel and the baseband digital channel, then amplifies the signal through a power amplifier (PA), and then sends it to the antenna for transmission via the RF feeder. Terminal devices, such as mobile phones and tablets, receive the radio waves transmitted by the antenna through the wireless channel and then demodulate their own signal.

[0076] Referring back to Figure 1, the base station also includes a power supply unit, which can be used to supply power to structures such as the transmission unit, baseband unit, and control unit.

[0077] Figure 2 shows a structural diagram of another electronic device, taking a mobile phone as an example. The mobile phone may include a mid-frame 11, a back cover 12, and a display screen 13. The mid-frame 11 includes a support plate 111 for supporting the display screen 13, and a frame 110 around the support plate 111.

[0078] Figure 3 illustrates a circuit diagram of an electronic device. This example includes a transceiver and an RF front-end circuit. The transceiver is coupled to an antenna via the RF front-end circuit (or RF front-end device). The RF front-end circuit includes a power amplifier. For example, the power amplifier can be coupled to the antenna via a switch and a filter; alternatively, the power amplifier can be coupled to the antenna via a duplexer and a switch. In other examples, other electronic components can be added to the circuit in Figure 3. Figure 3 is an exemplary circuit diagram of a power amplifier provided in this application. In this circuit, the power amplifier (e.g., a GaN HEMT semiconductor device unit) serves as the main component, and during operation, it needs to work with RF signal input / output matching, bias circuits, and electronic components such as capacitors and inductors to form a microwave monolithic integrated circuit.

[0079] In the circuit diagram shown in Figure 3, the switch can be a capacitive switch, or it can be made using micro-electro-mechanical system (MEMS) technology. MEMS switches typically use the deformation of a cantilever beam to contact the metal below it to achieve the switching between on and off states. Taking a capacitive switch as an example, for instance, the end of the cantilever beam fixed on the substrate is located above the capacitor and there is a gap between it and the upper electrode plate of the capacitor. When the cantilever beam is pulled down to contact the upper electrode of the capacitor, the switching state is completed.

[0080] As shown in Figure 4, Figure 4 illustrates one configuration of the MEMS switch in an electronic device according to this application. The MEMS switch 200 can be mounted on a circuit board 100, such as a printed circuit board (PCB). The MEMS switch 200 is electrically connected to the circuit board 100. Other chips, such as a control circuit 300, can also be mounted on the circuit board 100. The control circuit 300 can be electrically connected to the MEMS switch 200 to control the signals of the MEMS switch 200.

[0081] To optimize MEMS switch performance, such as reducing the risk of leakage current in cantilever beams, embodiments of this application provide some feasible MEMS switch structures, as detailed below.

[0082] Figure 5 is a three-dimensional structural diagram of a MEMS switch according to an embodiment of this application, and Figure 6 is an example of a cross-sectional view AA of Figure 5.

[0083] Referring to Figures 5 and 6, in this example, the MEMS switch includes a substrate 1, a capacitor 2, and a switch structure 3. The substrate 1 serves as a carrier for mounting the capacitor 2 and the switch structure 3.

[0084] The capacitor 2 includes a first electrode 21, a capacitor layer 22, and a second electrode 23. In some examples, the first electrode 21, the capacitor layer 22, and the second electrode 23 are stacked sequentially along the thickness direction of the substrate 1. For example, the first electrode 21, the capacitor layer 22, and the second electrode 23 are stacked from bottom to top along the thickness direction Z of the substrate 1.

[0085] The first electrode 21, the capacitor layer 22, and the second electrode 23 constitute a capacitor structure that allows alternating current to pass through while blocking direct current. For example, when the capacitive switch is in the open state, the electrical signal flowing into the first electrode 21 of the capacitive switch can be an alternating current signal. This signal can flow in through the first electrode 21, flow out through the second electrode 22, and be processed by the subsequent amplification circuit.

[0086] As shown in Figure 6, the first electrode 21 and the capacitor layer 22 are disposed in the substrate 1. For example, a groove can be formed in the substrate 1, and the first electrode 21 and the capacitor layer 22 are disposed in the groove, with the first electrode 21 surrounding the capacitor layer 22. In addition, the MEMS switch also includes a contact 4, which is disposed on the first electrode 21 and electrically connected to the first electrode 21.

[0087] Alternatively, it can be understood that: the first electrode 21 includes a side portion 211 and a bottom portion 212, the side portion 211 is located on the side wall of the groove, and the bottom portion 212 is located on the bottom wall of the groove; wherein, the bottom portion 212, the capacitor layer 22, and the second electrode 23 are stacked along the thickness direction of the substrate; the contact 4 is connected to the side portion 212 of the first electrode 21.

[0088] Continuing with Figure 6, the switch structure 3 is disposed on the substrate 1. The switch structure 3 includes a fixed part 31 and a cantilever part 32. The fixed part 31 is connected to the substrate 1, and the cantilever part 32 extends above the contact 4.

[0089] In this application example, the cantilever portion 32 of the switch structure 3 is parallel to the surface of the substrate 1. For example, in Figure 5, the surface of the substrate 1 is located in the XY plane, and the cantilever portion 32 is parallel to the XY plane.

[0090] The fixed portion 31 (also called the anchor structure) of the switch structure 3 extends in a direction perpendicular to the cantilever portion 32 and is connected to one end of the cantilever portion 32. It can be understood that the switch structure 3 in this application example has an L-shaped structure.

[0091] The working principle of the MEMS switch in this application example is described below with reference to Figure 7:

[0092] In some application scenarios, such as when a communication terminal needs to select and switch frequency bands, or when it needs to cut off some frequency band signals, the control circuit connected to the MEMS switch inputs a DC signal. This DC signal can be used as a logic level signal to control the on and off states of the MEMS switch. When the DC signal flows in from the control pin of the MEMS switch, as shown in Figure 7, the first electrode 21 carries a positive charge, and the second electrode 23 also carries a positive charge. Because the contact 4 is electrically connected to the first electrode 21, the contact 4 carries a positive charge. The switch structure 3 can be grounded. The fixed part 31 and the cantilever part 32 of the switch structure 3 both carry a negative charge. Due to the electrostatic force generated by the attraction between different shapes, the cantilever part 32 contacts the contact 4, forming a closed loop.

[0093] When an electrical signal flows in from the input pin of the MEMS switch, the signal passes through the second electrode 23, the capacitor layer 22, the first electrode 21, the cantilever portion 32, and the fixed portion 31, thus guiding the signal to the ground wire. This prevents certain frequency bands of electrical signals from flowing to the input pin of the MEMS switch, allowing the communication terminal to operate in the frequency band desired by the user.

[0094] There are multiple ways to ground the switch structure 3. For example, in the example of Figure 7, a conductive via 54 can be opened in the substrate 1, and a pad 64 can be provided on the side of the substrate 1 away from the switch structure 3. The conductive via 54 connects the pad 64 and the fixing part 31. In this way, the switch structure 3 can be grounded through the conductive via 54 and the pad 64. The pad 64 can be electrically connected to the ground line on the circuit board 100 shown in Figure 4.

[0095] In the examples of Figures 6 and 7, the first electrode 21 is connected to the contact 4, which is used to contact or separate from the cantilever portion 32 of the switch structure 3 to realize the conduction or cutoff of the MEMS switch.

[0096] The second electrode 23 can be electrically connected to the control circuit. Figure 8 provides an example of one way in which the second electrode 23 is electrically connected to the control circuit. Figure 8 is an example of a BB cross-sectional view of Figure 5.

[0097] In this method, the second electrode 23 includes a first part 231 and a second part 232. The projection of the first part 231 onto the first electrode 21 is located within the boundary of the first electrode 21, and the projection of the second part 232 onto the first electrode 21 is located outside the boundary of the first electrode 21. For example, the size of the second electrode 23 in the X direction can be made larger than the size of the first electrode 21 in the X direction.

[0098] Conductive vias 51 can be formed in the substrate 1, and pads 61 can be provided on the side of the substrate 1 away from the capacitor 2. The conductive vias 51 connect the pads 61 and the second part 232 of the second electrode 23. The MEMS switch shown in Figure 8 can be set on the circuit board 100 shown in Figure 4. The second electrode 23 can be electrically connected to the control circuit 300 through the conductive vias 51, the pads 61, and the circuit board 100, so that the control circuit 300 can control the signal of the second electrode 23.

[0099] Returning to Figures 5 and 6, in this example, the first electrode 21 and the capacitor layer 22 are disposed in the groove of the substrate 1, and the second electrode 23 is located on the substrate 1. That is, the first electrode 21 and the capacitor layer 22 fill the groove, the surfaces of the first electrode 21 and the capacitor layer 22 are basically flush with the surface of the substrate 1, and the second electrode 23 is stacked on the capacitor layer 22.

[0100] Since a contact 4 is to be set up to connect with the first electrode 21, in this embodiment, as shown in Figure 6, the capacitor layer 22 has a side surface S close to the contact 4, and the second electrode 23 has a side surface M close to the contact 4. Side surface M is further away from the contact than side surface S. Alternatively, it can be understood that the switch structure 3 and the capacitor 2 are arranged along a first direction parallel to the substrate 1, for example, along the X direction parallel to the substrate 1. The size of the second electrode 23 in the first direction is smaller than the size of the capacitor layer 22 in the first direction, and the second electrode 23 is further away from the contact than the capacitor layer 22. In this way, space can be provided to avoid the contact 4. In addition, when the cantilever portion 32 contacts the contact 4, the distance between the cantilever portion 32 and the second electrode 23 can be increased to avoid arcing between the cantilever portion 32 and the second electrode 23.

[0101] In the above example, the side S of the capacitor layer 22 can be referred to as the first side, and the side M of the second electrode 23 can be referred to as the second side.

[0102] Figures 9 to 14 are process structure diagrams corresponding to a method for fabricating a MEMS switch according to an embodiment of this application.

[0103] As shown in Figure 9, a groove is formed in the substrate 1.

[0104] As shown in Figure 10, a first electrode 21 and a capacitor layer 22 are formed in the groove, and a second electrode 23 is formed on the capacitor layer 22. The second electrode 23 protrudes from the surface of the substrate 1.

[0105] The first electrode 21 includes a portion formed on the side of the groove and a portion formed on the bottom of the groove.

[0106] Continuing with Figure 10, a contact 4 is provided on the first electrode 21.

[0107] As shown in Figure 11, a sacrificial layer 400 is formed, which covers the substrate 1, the contact 4, and the second electrode 23.

[0108] The material of the sacrificial layer 400 may include at least one of Si, Ge, GeSi, etc. Of course, it may also include other materials.

[0109] As shown in Figure 12, a window 401 is opened on the sacrificial layer 400.

[0110] As shown in Figure 13, a switch structure 3 is fabricated. The switch structure 3 includes a portion located within the window 401, which is used to connect with the substrate 1 and serve as a fixed part of the switch structure. The switch structure 3 also includes a portion disposed on the sacrificial layer 400, which extends above the contact 4.

[0111] As shown in Figure 14, the sacrificial layer 400 is removed. This yields a switch structure 3 comprising a fixed portion 31 and a cantilever portion 32. The cantilever portion 32 extends above the contact 4 and has a gap with the contact 4. The cooperation between the cantilever portion 32 and the contact 4 enables the MEMS switch to be turned on or off.

[0112] Figure 15 is a structural diagram of a MEMS switch in the related technology. The MEMS switch includes a substrate 1, a capacitor 2 disposed on the substrate 1, and a switch structure 3. The switch structure 3 includes a cantilever portion 32 and a support portion 31. The support portion 31 has a corner, which is the part circled by the dashed line in Figure 15.

[0113] Figures 16 to 20 illustrate the fabrication process structure corresponding to the method for fabricating the MEMS switch shown in Figure 15.

[0114] As shown in Figure 16, a capacitor 2 is fabricated on the surface of a substrate 1. That is, the capacitor 2 includes at least two electrode layers and at least one capacitor layer, all stacked on the substrate 1, and the capacitor 2 protrudes from the surface of the substrate 1.

[0115] As shown in Figure 17, a sacrificial layer 400 is formed, which covers the substrate 1 and the capacitor 2.

[0116] As shown in Figure 18, a window 401 is opened on the sacrificial layer 400.

[0117] As shown in Figure 19, a switch structure 3 is fabricated. The switch structure 3 includes a portion located inside the window 401, which is used to connect with the substrate 1 and serve as a fixed part of the switch structure. The switch structure 3 also includes a portion disposed on the sacrificial layer 400, which extends above the capacitor 2.

[0118] As shown in Figure 20, remove the sacrificial layer 400.

[0119] In the MEMS switch fabricated using this method, since the electrodes and capacitor layer of capacitor 2 are both disposed on the surface of substrate 1, as shown in Figures 17 and 18, the sacrificial layer 400 forms a corner on the side of capacitor 2. Consequently, as shown in Figure 20, the fabricated switch structure 3 includes the corner portion indicated by the dashed circle.

[0120] When the switch structure 3 comes into contact with the capacitor 2, as shown in Figure 20, since the corner part is close to the capacitor 2, for example, the distance is about a few micrometers, the current transmitted by the switch structure 3 is large, and arcing is likely to occur between the corner and the capacitor 2. For example, the switch structure 3 can be made of metal. In this case, the arcing phenomenon can melt the corner of the metal switch structure 3, causing the switch structure 3 to fail.

[0121] Returning to Figure 14 of this application example, in the MEMS switch of this application example, the electrode that contacts the switch structure 3 is placed in the groove of the substrate 1. That is, in this application, the electrode that contacts the switch structure 3 is not placed above the surface of the substrate 1, but is buried in the substrate 1, and contacts the switch structure 3 through the provided contact point 4 to achieve switching. Compared with the structure shown in Figure 20, this application can avoid arcing between the corner position and the capacitor 2, reduce the leakage current of the switch structure, and also avoid reducing the strength of the switch structure due to the corner. Therefore, this application can improve the strength of the switch structure and increase the switching frequency of the switch structure while reducing the leakage current, thus optimizing the performance of the switching device.

[0122] Alternatively, it can be understood that in the technology shown in Figures 16 to 20, the first electrode 21, the capacitor layer 22, and the second electrode 23 are all disposed above the substrate 1. The switch structure 3 can directly contact the electrode located at the top to achieve switching. Then, as shown in Figure 18, after the sacrificial layer 400 is formed on the stacked first electrode, capacitor layer, and second electrode, when the switch structure 3 is formed, as shown in Figure 19, because it is on the substrate and the stacked first electrode, capacitor layer, and second electrode are relatively thick, the switch structure 3 needs to extend above the electrode located at the top. The switch structure formed in this way will have a corner that is close to the capacitor. Since this corner is close to the capacitor, arcing is likely to occur.

[0123] However, in this application, since the first electrode of the capacitor, or the first electrode and the capacitor layer, or the first electrode, the capacitor layer and the second electrode are disposed in the substrate, and the contact 4 connected to the first electrode 21 is made to contact the switch structure 3 to achieve switching, the thickness of the contact located on the substrate is significantly compressed compared to the first electrode, the capacitor layer and the second electrode stacked on the substrate. Therefore, as shown in FIG12, after covering the contact 4 with the sacrificial layer 400, the switch structure 3 is then fabricated. The fabricated switch structure 3 will not have a corner that is close to the capacitor, but includes a fixed portion 31 perpendicular to the substrate surface and a cantilever portion 32 perpendicular to the extension direction of the fixed portion 31. Compared with the prior art with corners, this application can avoid arcing between the corner and the capacitor, thereby reducing the leakage current of the switch structure.

[0124] Figure 21 is another structural diagram of the MEMS switch given in the embodiment of this application. For example, Figure 21 can be another example of the AA cross-sectional view of Figure 5.

[0125] In this example, the MEMS switch includes a substrate 1, a capacitor 2, and a switch structure 3. The capacitor 2 includes a first electrode 21, a capacitor layer 22, and a second electrode 23. The first electrode 21 is disposed within the substrate 1, meaning that the surface of the first electrode 21 can be flush with the surface of the substrate 1. The capacitor layer 22 and the second electrode 23 are stacked on the first electrode 21, with the capacitor layer 22 stacked between the first electrode 21 and the second electrode 23.

[0126] The substrate 1 has a contact 4, which is disposed on the first electrode 21 and electrically connected to the first electrode 21.

[0127] Continuing with Figure 21, the switch structure 3 includes a fixed part 31 and a cantilever part 32. The fixed part 31 is connected to the substrate 1, and the cantilever part 32 extends above the contact 4.

[0128] In this application example, the cantilever portion 32 of the switch structure 3 is parallel to the surface of the substrate 1, and the fixed portion 31 of the switch structure 3 extends in a direction perpendicular to the cantilever portion 32 and is connected to one end of the cantilever portion 32.

[0129] Since a contact 4 is to be set up to connect with the first electrode 21, in this embodiment, as shown in FIG21, the first electrode 21 has a side N close to the switch structure 3, and the capacitor layer 22 has a side S close to the switch structure 3. Side S is further away from the switch structure 3 than side N, thus providing space for setting up the contact 4. Side N of the first electrode 21 in this example can be referred to as the third side.

[0130] In the MEMS switch of this application example, the capacitor layer 22 and the second electrode 23 are disposed on the substrate, while the electrode that contacts the switch structure 3 is disposed in the groove of the substrate 1 and contacts the switch structure 3 through the provided contact 4 to achieve switching. Compared with the structure shown in FIG20, this application can also avoid arcing between the corner position and the capacitor 2, reduce the leakage current of the switch structure, and does not reduce the strength of the switch structure due to the corner. Therefore, this application can improve the strength of the switch structure and increase the switching frequency of the switch structure while reducing the leakage current, thus optimizing the performance of the switching device.

[0131] Continuing with Figure 21, the capacitor layer 22 has a side surface S near the contact 4, and the second electrode 23 has a side surface M near the contact 4. Side surface M is further away from the contact than side surface S. When the cantilever portion 32 contacts the contact 4, it can increase the distance between the cantilever portion 32 and the second electrode 23, thus preventing arcing between the cantilever portion 32 and the second electrode 23.

[0132] Figure 22 exemplarily illustrates one way in which the second electrode 23 is electrically connected to the control circuit. Figure 22 can be another example of the BB cross-sectional view of Figure 5.

[0133] In this method, the second electrode 23 includes a first part 231 and a second part 232. The projection of the first part 231 onto the first electrode 21 is located within the boundary of the first electrode 21, and the projection of the second part 232 onto the first electrode 21 is located outside the boundary of the first electrode 21. For example, the size of the second electrode 23 in the X direction can be made larger than the size of the first electrode 21 in the X direction.

[0134] Conductive vias 51 can be formed in the substrate 1, and pads 61 can be provided on the side of the substrate 1 away from the capacitor 2. Conductive vias 52 connect pads 61 and the second part 232 of the second electrode 23. The MEMS switch shown in Figure 22 can be set on the circuit board 100 shown in Figure 4. The second electrode 23 can be electrically connected to the control circuit 300 through conductive vias 51, pads 61, and circuit board 100, so that the control circuit 300 can control the signal of the second electrode 23.

[0135] Figure 23 is another structural diagram of the MEMS switch given in the embodiment of this application. For example, Figure 23 can be another example of the AA cross-sectional view of Figure 5.

[0136] In this example, in capacitor 2, the first electrode 21, capacitor layer 22, and second electrode 23 are all disposed within substrate 1. That is, the first electrode 21, capacitor layer 22, and second electrode 23 fill the groove formed in substrate 1. The second electrode 23, capacitor layer 22, and first electrode 21 are stacked from bottom to top along a direction perpendicular to the thickness direction of substrate 1. That is, the second electrode 23 is closer to the lower surface of the substrate than the first electrode 21, and this lower surface is located opposite the upper surface where the switch structure is disposed.

[0137] Continuing with Figure 23, the switch structure 3 includes a fixed part 31 and a cantilever part 32. The fixed part 31 is connected to the substrate 1, and the cantilever part 32 extends above the contact 4.

[0138] In this example, since the entire structure of capacitor 2 is placed inside substrate 1, the leakage current of the switching structure can be reduced, the strength of the switching structure can be improved, the switching frequency of the switching structure can be increased, and the performance of the switching device can be optimized, while the overall height of the switching device can also be reduced.

[0139] Continuing with Figure 23, in this example, since the second electrode 23, capacitor layer 22, and first electrode 21 are stacked from bottom to top along a direction perpendicular to the substrate 1, a conductive via 52 (which can be referred to as the second conductive via) can be provided in the substrate 1. A pad 62 (which can be referred to as the second pad) is provided on the side of the substrate 1 opposite to the first electrode 21. The conductive via 52 connects the pad 62 and the second electrode 23. The MEMS switch shown in Figure 23 can be set on a circuit board. The first electrode 21 can be electrically connected to the control circuit through the conductive via 52, the pad 62, and the circuit board, so that the control circuit can control the signal of the first electrode 21.

[0140] Figure 24 is another structural diagram of the MEMS switch given in the embodiment of this application. For example, Figure 24 can be another example of the AA cross-sectional view of Figure 5.

[0141] The example in Figure 24 is the same as that in Figure 23 above. In the example in Figure 24, the first electrode 21, the capacitor layer 22 and the second electrode 23 are all disposed in the substrate 1. That is, the first electrode 21, the capacitor layer 22 and the second electrode 23 fill the groove opened in the substrate 1.

[0142] The example in Figure 24, which differs from Figure 23 above, includes a first electrode 21, a capacitor layer 22, and a second electrode 23 stacked from bottom to top along a direction perpendicular to the thickness direction of the substrate 1.

[0143] As shown in Figure 24, in addition to reducing leakage current in the switch structure, improving the strength of the switch structure, increasing the switching frequency of the switch structure, and optimizing the performance of the switch device, the overall height of the switch device can also be reduced.

[0144] The MEMS switch provided in this application embodiment may also include a pull-down electrode 7. As shown in FIG24, there is a space between the cantilever portion 32 of the switch structure 3 and the substrate 1, and the pull-down electrode 7 can be disposed in the space.

[0145] In some examples, conductive vias 53 can be formed in the substrate 1, and a pad 63 is provided on the side of the substrate 1 opposite to the pull-down electrode 7. The pull-down electrode 7 is connected to the pad 63 through the conductive via 53. For example, the pad 63 can be grounded. In this way, when the cantilever portion 32 of the switch structure 3 moves down to contact the contact 4, the pull-down electrode 7 can increase the pull-down force of the cantilever portion 32, so that the cantilever portion 32 quickly contacts the contact 4, thereby turning off the switch device.

[0146] Figure 25 is another structural diagram of the MEMS switch given in the embodiment of this application. For example, Figure 25 can be another example of the AA cross-sectional view of Figure 5.

[0147] Both Figure 25 and Figure 24 above include a pull-down electrode 7, which is connected to a pad 63 (which may be referred to as a third conductive via) provided in the substrate 1. In the example of Figure 24, the pull-down electrode 7 is provided on the surface of the substrate 1, while in the example of Figure 25, the pull-down electrode 7 is provided inside the substrate 1.

[0148] In the MEMS switch of this application example, substrate 1 can be a silicon substrate or a glass substrate. Since glass substrates have better insulation properties, this can reduce insertion loss when transmitting high-frequency signals and improve the performance of the switching device.

[0149] In the MEMS switch of this application example, as shown in FIG26, it may further include a first conductor 81 and a second conductor 82. The first conductor 81 and the second conductor 82, as well as the second electrode 23, may be referred to as a coplanar waveguide. The coplanar waveguide includes the second electrode 23 for transmitting electrical signals, and the first conductor 81 and the second conductor 82, which serve as ground wires, disposed on both sides of the second electrode 23.

[0150] In some examples, the fixing portion 31 of the switch structure 3 can be located on the first conductor 81 or the second conductor 82. In other examples, as shown in Figure 26, the fixing portion 31 of the switch structure 3 is not located on the first conductor 81 or the second conductor 82. The first conductor 81 is grounded through a conductive via and a pad, the second conductor 82 is grounded through a conductive via and a pad, and the fixing portion 31 of the switch structure 3 is grounded through a conductive via and a pad. This avoids interference from signals in the first conductor or the second conductor in the switch structure.

[0151] As shown in Figure 27, which is a top view of the MEMS switch according to an embodiment of this application, the contacts 4 can include multiple contacts. For example, Figure 27 shows two contacts 4 spaced apart, and the multiple contacts 4 can be spaced apart along the extension direction of the cantilever portion 32. By setting multiple contacts 4, the contact area between the cantilever portion 32 and the contacts 4 can be increased, thereby improving the stability of the electrical connection between the switch structure and the contacts.

[0152] As shown in Figure 28, which is a structural diagram of a switch structure 3 according to an example of this application, in conjunction with Figures 27 and 28, the cantilever portion 32 can be a block structure or a sheet structure, and the fixing portion 31 is provided at the edge of the cantilever portion 32 and is located in the middle of the edge.

[0153] When the MEMS switch includes a pull-down electrode 7 located below the cantilever portion 32, the cantilever portion 32 shown in Figures 27 and 28 can increase the overlap area with the pull-down electrode 7, thereby increasing the pull-down force.

[0154] Figure 29 is a flowchart of a method for fabricating a MEMS switch according to an embodiment of this application.

[0155] Step S1: Create a groove in the substrate.

[0156] Step S2: A capacitor and a contact are fabricated. The capacitor includes a first electrode, a capacitor layer, and a second electrode. The first electrode, the capacitor layer, and the second electrode are stacked sequentially along the thickness direction of the substrate. The first electrode is located in a groove. At least a portion of the contact protrudes from the surface of the substrate and is connected to the first electrode.

[0157] Among the available processes, these film structures can be grown using metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), physical vapor deposition (PVD), low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD), or atomic layer deposition (ALD).

[0158] In some processes, a first electrode and a capacitor layer can be fabricated within a groove, and a second electrode can be fabricated on a substrate; alternatively, a first electrode can be fabricated within a groove, and a capacitor layer and a second electrode can be fabricated on a substrate; or, a first electrode, a capacitor layer, and a second electrode can be fabricated within a groove. That is, at least the first electrode can be disposed within the groove.

[0159] Step S3: Prepare a sacrificial layer that at least covers the contact.

[0160] For example, at least one of materials such as Si, Ge, and GeSi can be selected to prepare the sacrificial layer.

[0161] Step S4: Create a window within the sacrificial layer.

[0162] Step S5: Obtain the switch structure, which includes a fixed part and a cantilever part. At least a portion of the fixed part is located within the opening, and the cantilever part is located on the sacrificial layer and extends above the contact.

[0163] Step S6: Remove the sacrificial layer. This allows for a gap between the cantilever portion and the contact.

[0164] Combining the above steps, when performing step S1, at least the first electrode of the capacitor is placed in the groove in the substrate, and a contact can also be provided. Because the thickness of the contact located on the substrate is significantly compressed compared to the first electrode, capacitor layer and second electrode stacked on the substrate, and then after covering the contact with a sacrificial layer, the switch structure is fabricated. The resulting switch structure will not have a corner that is close to the capacitor.

[0165] In some alternative fabrication processes, the fabrication method may include, before the sacrificial layer is formed, forming a pull-down electrode; the pull-down electrode may be located on the substrate, or a groove may be cut in the substrate and the pull-down electrode may be placed in the groove.

[0166] When a pull-down electrode is fabricated, a window is made in the sacrificial layer, including: the window is located on the side of the pull-down electrode away from the capacitor, so that the pull-down electrode is located below the cantilever portion of the switching structure.

[0167] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0168] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A MEMS switch, characterized in that, include: Substrate; A capacitor includes a first electrode, a capacitor layer, and a second electrode, wherein the first electrode, the capacitor layer, and the second electrode are stacked sequentially along the thickness direction of the substrate, and the first electrode is located within the substrate; A contact, at least a portion of which protrudes from the surface of the substrate, is connected to the first electrode; A switch structure is disposed on the substrate. The switch structure includes a fixed part and a cantilever part. The fixed part is connected to the substrate. The extension direction of the fixed part is perpendicular to the extension direction of the cantilever part. The extension direction of the cantilever part is parallel to the surface of the substrate and extends above the contact point. The cantilever part is used to contact the contact point.

2. The MEMS switch according to claim 1, characterized in that, The capacitor layer is located inside the substrate, and the second electrode is located on the substrate; The first electrode includes a side portion and a bottom portion, and the contact is connected to the side portion; or, Both the capacitor layer and the second electrode are located on the substrate.

3. The MEMS switch according to claim 2, characterized in that, The capacitor layer has a first side surface, and the second electrode has a second side surface. Both the first side surface and the second side surface are close to the switch structure, and the second side surface is farther away from the contact point than the first side surface.

4. The MEMS switch according to claim 1, characterized in that, Both the capacitor layer and the second electrode are located within the substrate; The substrate has a first surface and a second surface opposite to each other, and the switch structure is disposed on the first surface; The first electrode includes a side portion and a bottom portion, and the contact is connected to the side portion; The bottom portion, the capacitor layer, and the second electrode are disposed from the second surface to the first surface.

5. The MEMS switch according to any one of claims 2-4, characterized in that, The second electrode includes a first part and a second part, wherein the projection of the first part onto the first electrode is located within the boundary of the first electrode, and the projection of the second part onto the first electrode is located outside the boundary of the first electrode. The MEMS switch further includes a first conductive via and a first pad. The first pad is disposed on the surface of the substrate opposite to the switch structure. The first conductive via passes through the substrate to connect the second part and the first pad.

6. The MEMS switch according to claim 1, characterized in that, Both the capacitor layer and the second electrode are located within the substrate; The substrate has a first surface and a second surface opposite to each other, and the switch structure is disposed on the first surface; The second electrode, the capacitor layer, and the first electrode are disposed from the second surface to the first surface.

7. The MEMS switch according to claim 6, characterized in that, The MEMS switch further includes a second conductive via and a second pad. The second pad is disposed on the surface of the substrate opposite to the switch structure. The second conductive via passes through the substrate and connects the second electrode and the second pad.

8. The MEMS switch according to any one of claims 1-7, characterized in that, The MEMS switch also includes a pull-down electrode located in the space between the cantilever portion and the substrate.

9. The MEMS switch according to claim 8, characterized in that, The MEMS switch further includes a third conductive via and a third pad. The third pad is disposed on the surface of the substrate opposite to the switch structure. The third conductive via passes through the substrate and connects the pull-down electrode to the third pad.

10. The MEMS switch according to any one of claims 1-9, characterized in that, The MEMS switch further includes a fourth conductive via and a fourth pad. The fourth pad is disposed on the surface of the substrate opposite to the switch structure. The fourth conductive via passes through the substrate and connects the fixing part to the fourth pad.

11. The MEMS switch according to any one of claims 1-10, characterized in that, The contact points are multiple and are spaced apart along a direction perpendicular to the extension direction of the cantilever portion.

12. A radio frequency front-end device, characterized in that, include: filter; The MEMS switch as described in any one of claims 1-11, wherein the MEMS switch is electrically connected to the filter.

13. An electronic device, characterized in that, include: Control circuit; The control circuit is electrically connected to the MEMS switch as described in any one of claims 1-11 or the radio frequency front-end device as described in claim 12.

14. A method for fabricating a MEMS switch, characterized in that, The preparation method includes: A groove is formed in the substrate; A capacitor and contacts are fabricated. The capacitor includes a first electrode, a capacitor layer, and a second electrode. The first electrode, the capacitor layer, and the second electrode are stacked sequentially along the thickness direction of the substrate. The first electrode is located in the groove. At least a portion of the contacts protrudes from the surface of the substrate, and the contacts are connected to the first electrode. A sacrificial layer is formed, wherein the sacrificial layer at least covers the contact point; A window is made within the sacrificial layer; A switch structure is obtained, the switch structure including a fixed part and a cantilever part, at least a portion of the fixed part is located inside the opening, and the cantilever part is located on the sacrificial layer and extends above the contact; Remove the sacrificial layer.

15. The method for fabricating a MEMS switch according to claim 14, characterized in that, The capacitor is manufactured by: A first electrode and a capacitor layer are formed within the groove, and a second electrode is formed on the substrate; or... A first electrode is formed within the groove, and a capacitor layer and a second electrode are formed on the substrate; or... A first electrode, a capacitor layer, and a second electrode are formed within the groove.

16. The method for fabricating a MEMS switch according to claim 14 or 15, characterized in that, Before obtaining the sacrificial layer, the preparation method further includes: obtaining a pull-down electrode; Creating a window within the sacrificial layer includes: the window being located on the side of the pull-down electrode away from the capacitor.

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