Micro-electromechanical system switch and method for manufacturing the same

Abstract

The present invention provides a micro-electromechanical system switch and a preparation method thereof, which belongs to the field of radio frequency switch technology. The micro-electromechanical system switch disclosed in the present invention includes a substrate substrate; a membrane bridge, which includes a first bridge body arranged opposite to the substrate substrate, and at least one connecting arm arranged on the substrate substrate for supporting the first bridge body; a driving electrode, which is arranged on a side of the first bridge body close to the substrate substrate, and there is a certain space between the driving electrode and the first bridge body; a first insulating layer, which at least covers the surface of the driving electrode close to the first bridge body; an auxiliary function structure, which is at least arranged on the first bridge body, and the elastic modulus of the auxiliary function structure is greater than the elastic modulus of the first bridge body.

Description

Technical Field

[0001] The present invention belongs to the technical field of radio frequency switches, and in particular relates to a micro-electromechanical system switch and a preparation method thereof. Background Art

[0002] MEMS (Micro-Electro-Mechanical Systems) switch is a switch device made using MEMS technology. It controls the conduction and disconnection of signals through the movement of micromechanical structures. MEMS switch is one of the core components of microwave and radio frequency transceiver systems, and is widely used in satellite communications, radar, missile control and other fields. Compared with traditional PIN and FET switch devices, MEMS switch not only has extremely excellent microwave performance such as high isolation, low loss, low insertion loss, and high linearity, but also has the characteristics of easy mass production, small size, and easy integration with advanced microwave and radio frequency circuits. It is a key technology to realize miniaturized, low-cost, and high-performance microwave transceiver front-end systems. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art and provides a micro-electromechanical system switch and a method for preparing the same.

[0004] In a first aspect, the present disclosure provides a micro-electromechanical system switch, comprising: a substrate; a membrane bridge, comprising a first bridge body arranged opposite to the substrate, and at least one connecting arm arranged on the substrate for supporting the first bridge body; a driving electrode, arranged on a side of the first bridge body close to the substrate, and spaced apart from the first bridge body; a first insulating layer, covering at least a surface of the driving electrode close to the first bridge body; an auxiliary functional structure, arranged at least on the first bridge body, and the elastic modulus of the auxiliary functional structure is greater than the elastic modulus of the first bridge body.

[0005] Wherein, the auxiliary functional structure is attached to a side of the first bridge body away from the driving electrode.

[0006] Wherein, the auxiliary functional structure is attached to a side of the first bridge body close to the driving electrode.

[0007] Wherein, the membrane bridge further comprises a second bridge body arranged on a side away from the first bridge body; and the auxiliary functional structure is arranged between the first bridge body and the second bridge body.

[0008] Wherein, the thickness of the first bridge body is greater than the thickness of the second bridge body.

[0009] The auxiliary functional structure is arranged on the first bridge body, and the orthographic projection of the auxiliary functional structure overlaps with the orthographic projection of the first bridge body.

[0010] Among them, when the membrane bridge includes only one connecting arm, the orthographic projection of the auxiliary functional structure on the substrate substrate includes a first side, a second side, a third side and a fourth side, and the orthographic projection of the first bridge body on the substrate substrate includes a fifth side, a sixth side, a seventh side and an eighth side; the first side and the third side are arranged opposite to each other, the second side and the fourth side are arranged opposite to each other, the fifth side and the seventh side are arranged opposite to each other, and the sixth side and the eighth side are arranged opposite to each other; the first side, the second side and the third side coincide with the fifth side, the sixth side and the seventh side respectively; the distance between the fourth side and the eighth side is 1 / 6-1 / 2 of the length of the first side or the third side.

[0011] Wherein, when the membrane bridge includes only one connecting arm, the distance from a point on the first bridge body close to the connecting arm to the substrate is smaller than the distance from a point on the membrane bridge far from the bridge arm to the substrate.

[0012] Wherein, the MEMS switch further comprises: a convex structure; the convex structure is a conductive structure; the orthographic projections of the convex structure and the membrane bridge on the substrate at least partially overlap.

[0013] Wherein, the convex structure includes a first convex substructure and a second convex substructure; the first convex substructure is arranged on a side of the second convex substructure away from the substrate; and the first convex substructure is a conductive structure.

[0014] Wherein, the membrane bridge includes two connecting arms.

[0015] Wherein, when the membrane bridge includes only one connecting arm, the connecting arm includes a supporting portion and an anchor point; the anchor point is arranged between the substrate and the supporting portion, and the orthographic projections of the anchor point and the supporting portion on the substrate at least partially overlap.

[0016] Wherein, the material of the auxiliary functional structure includes graphene.

[0017] In the second aspect, the present disclosure also provides a method for preparing a micro-electromechanical system switch, which includes: providing a substrate; forming a driving electrode on the substrate; forming a first insulating layer on the side of the driving electrode facing away from the substrate; the first insulating layer at least covers the side of the driving electrode facing away from the substrate; forming a sacrificial layer having at least one via hole on the first insulating layer; forming a membrane bridge on the side of the sacrificial layer facing away from the substrate; the steps of forming the membrane bridge include: forming a connecting arm in the via hole and forming a first bridge body on the side of the sacrificial layer facing away from the substrate; forming the auxiliary functional structure on the first bridge body; the elastic modulus of the auxiliary functional structure is greater than the elastic modulus of the first bridge body; and removing the sacrificial layer through a sacrificial layer release process.

[0018] Wherein, the step of forming the auxiliary functional structure includes: forming the auxiliary functional structure on a side of the first bridge body away from the substrate.

[0019] The step of forming the auxiliary functional structure includes: forming the auxiliary functional structure on the sacrificial layer at a side away from the substrate; and forming the first bridge on the auxiliary functional structure at a side away from the substrate.

[0020] Wherein, the step of forming a membrane bridge further includes: forming a second bridge body on a side of the auxiliary functional structure away from the substrate.

[0021] Among them, the preparation method of the micro-electromechanical system switch also includes: before forming the driving electrode, forming a second insulating layer on the substrate; before forming the first insulating layer, forming a second convex substructure on the second insulating layer; before forming the sacrificial layer, forming a first convex substructure on the side of the first insulating layer away from the second convex substructure; the first convex substructure is a conductive structure; the first bridge body, the first convex substructure and the second convex substructure have at least partially overlapping orthographic projections on the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A cross-sectional view of a MEMS switch according to an embodiment of the present disclosure;

[0023] Figure 2 is another cross-sectional view of a MEMS switch according to an embodiment of the present disclosure;

[0024] Figure 3 yes Figure 2 A schematic diagram of an orthographic projection of a first bridge body and an auxiliary functional structure in the MEMS switch shown on a substrate;

[0025] Figure 4is another cross-sectional view of a MEMS switch according to an embodiment of the present disclosure;

[0026] Figure 5 is another cross-sectional view of a MEMS switch according to an embodiment of the present disclosure;

[0027] Figure 6 is another cross-sectional view of a MEMS switch according to an embodiment of the present disclosure;

[0028] Figure 7 is another cross-sectional view of a MEMS switch according to an embodiment of the present disclosure;

[0029] Figure 8 A flow chart of a method for manufacturing a MEMS switch provided in an embodiment of the present disclosure;

[0030] Fig. 9 is a schematic diagram of step S11 of an embodiment of the present disclosure;

[0031] Fig.10 is a schematic diagram of step S12 of an embodiment of the present disclosure;

[0032] Fig.11 is a schematic diagram of step S13 of an embodiment of the present disclosure;

[0033] Fig.12 is a schematic diagram of step S14 of an embodiment of the present disclosure;

[0034] Fig.13 is a schematic diagram of step S15 of an embodiment of the present disclosure;

[0035] Fig.14 is a schematic diagram of step S16 of an embodiment of the present disclosure;

[0036] Fig.15 is a schematic diagram of step S17 of an embodiment of the present disclosure;

[0037] Fig.16 Schematic diagram of step S18 of an embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0039] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate quantity restrictions, but indicate that there is at least one. Similar words such as "include" or "comprise" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0040] The embodiment of the present disclosure provides a micro-electromechanical system MEMS (Micro-Electro-Mechanical System) switch and a preparation method thereof. The MEMS switch of the embodiment of the present disclosure may be a radio frequency switch, which may be applied to the conduction or switching of control signals in radio frequency circuits. The MEMS switch of the embodiment of the present disclosure comprises a substrate 1, a driving electrode 5, a first insulating layer 6, a membrane bridge and an auxiliary functional structure 8. Among them, the material of the substrate 1 may be a silicon substrate, a glass substrate or a high-resistance silicon, etc., and its thickness may be 0.2mm-1mm. A driving electrode 5 is arranged on the substrate 1, and the signal on the driving electrode 5 can be used to control the shutdown of the MEMS switch. A membrane bridge is arranged on the side of the substrate 1 away from the substrate 1, and the membrane bridge comprises a first bridge body 2 arranged opposite to the substrate 1 and at least one connecting arm 11 for supporting the first bridge body 2, and the first bridge body 2 and the driving electrode 5 are arranged at intervals so that the first bridge body 2 can be elastically deformed toward the driving electrode 5 under the drive of the driving electrode 5 to realize the opening and closing of the MEMS switch. A first insulating layer 6 is provided on the surface of the driving electrode 5 close to the first bridge body 2 to prevent the driving electrode 5 and the first bridge body 2 from being electrically connected when the first bridge body 2 is elastically deformed toward the driving electrode 5. An auxiliary functional structure 8 is provided at least on the first bridge body 2, and the elastic modulus of the auxiliary functional structure 8 is greater than the elastic modulus of the first bridge body 2. Since the elastic modulus of the auxiliary functional structure 8 is greater than the elastic modulus of the first bridge body 2, when the first bridge body 2 is elastically deformed toward the driving electrode 5, the auxiliary functional structure 8 on the first bridge body 2 can share part of the stress and reduce the stress and deformation of the membrane bridge; when the first bridge body 2 rebounds away from the driving electrode 5, the tensile stress of the auxiliary functional structure 8 on the first bridge body 2 assists the first bridge body 2 to return to the initial position. In this way, the failure of the MEMS switch caused by insufficient elastic deformation of the first bridge body 2 is avoided, and the service life of the MEMS switch is improved.

[0041] In some embodiments, the material of the auxiliary functional structure 8 may be a graphene film. Since the graphene film has a high elastic modulus and good electrical conductivity, in the embodiments disclosed herein, the auxiliary functional structure 8 is only described as a graphene film.

[0042] In some embodiments, specific reference may be made to Figure 1 , Figure 1 FIG. 1 is a cross-sectional schematic diagram of a MEMS switch according to an embodiment of the present disclosure. Figure 1As shown, the MEMS switch of the embodiment of the present disclosure includes a substrate 1 and a second insulating layer 7 arranged on the substrate 1, and the second insulating layer 7 is used to reduce the roughness of the substrate 1, reduce the electromagnetic loss of the substrate 1, and increase the adhesion of the film layer arranged on the second insulating layer 7. A driving electrode 5 and a first insulating layer 6 are sequentially arranged on the side of the second insulating layer 7 away from the substrate 1, and the first insulating layer 6 completely covers the surface of the driving electrode 5 to protect the driving electrode 5. A membrane bridge is arranged on the side of the first insulating layer 6 away from the substrate 1, and the membrane bridge only includes a connecting arm 11 and a first bridge body 2 arranged opposite to the substrate 1, that is, the connecting arm 11 and the first bridge body 2 are combined to form a cantilever beam structure. In some embodiments, the connecting arm 11 includes a support portion 3 and an anchor point 4, and the anchor point 4 is arranged between the substrate 1 and the support portion 3, and the orthographic projections of the anchor point 4 and the support portion 3 on the substrate 1 at least partially overlap. In the embodiment of the present disclosure, the anchor point 4 is used to fix the cantilever beam structure. In some embodiments, the micro-electromechanical switch further comprises a convex structure 9, wherein the orthographic projections of the convex structure 9 and the membrane bridge on the substrate substrate 1 at least partially overlap, and the convex structure 9 is a conductive structure. In this way, the micro-electromechanical switch is easy to turn on and off. An auxiliary functional structure 8 is provided on the side of the first bridge body 2 away from the drive electrode 5. In some embodiments, the convex structure 9 comprises a first convex substructure 901 and a second convex substructure 902, wherein the first convex substructure 901 is provided on the side of the second convex substructure 902 away from the substrate substrate 1, and the first convex substructure 901 is a conductive structure. In this way, the preparation of the convex structure 9 is easy.

[0043] In the disclosed embodiment, the end of the cantilever beam structure close to the anchor point 4 is a fixed end, and the side away from the anchor point 4 is a free end. When the driving electrode 5 is loaded with an effective voltage, the free end of the cantilever beam structure undergoes elastic deformation toward the driving electrode 5 under the action of the electric field between the driving electrode 5 and the membrane bridge, until the membrane bridge contacts the convex structure 9, so that the MEMS switch is turned on or off. Specifically, in some embodiments, the anchor point 4 and the convex structure 9 can be respectively connected to the signal transmission line in the coplanar waveguide (CPW), and the ground wires in the coplanar waveguide are respectively arranged on both sides of the MEMS switch. In the embodiment of the present disclosure, since the anchor point 4 and the convex structure 9 are respectively connected to the two sections of insulated signal transmission lines in the coplanar waveguide line, when the membrane bridge in the MEMS switch is not in contact with the convex structure 9, the electrical signal on the signal transmission line is turned off by the MEMS switch; when the effective voltage is loaded on the driving electrode 5 of the MEMS switch, the membrane bridge in the MEMS switch undergoes elastic deformation and contacts the convex structure 9, and the membrane bridge in the MEMS switch electrically connects the two sections of insulated signal transmission lines in the coplanar waveguide line, the electrical signal on the signal transmission line is conducted via the membrane bridge, and the electrical signal on the signal transmission line is turned on by the MEMS switch.

[0044] In some embodiments, Figure 2 is a cross-sectional schematic diagram of another MEMS switch according to an embodiment of the present disclosure, Figure 3 yes Figure 2 The schematic diagram of the orthographic projection of the first bridge body 2 and the auxiliary functional structure 8 in the MEMS switch on the substrate 1 is shown. Figure 2 and Figure 3 As shown, the orthographic projection of the auxiliary functional structure on the substrate includes the first side 16, the second side 18, the third side 17 and the fourth side 19, and the orthographic projection of the first bridge body on the substrate includes the fifth side 12, the sixth side 14, the seventh side 13 and the eighth side 15; the first side 16 and the third side 17 are arranged oppositely, the second side 18 and the fourth side 19 are arranged oppositely, the fifth side 12 and the seventh side 13 are arranged oppositely, and the sixth side 14 and the eighth side 15 are arranged oppositely; the first side 16, the second side 18 and the third side 17 overlap with the fifth side 12, the sixth side 14 and the seventh side 13 respectively; the distance between the fourth side 19 and the eighth side 15 is 1 / 6-1 / 2 of the length of the fifth side 12 or the seventh side 13. In the embodiment of the present disclosure, the deformation amount of the first bridge body 2 when elastic deformation occurs is larger on the side away from the connecting arm 11, while the deformation amount of elastic deformation on the side close to the connecting arm 11 is smaller. Therefore, in the embodiment of the present disclosure, the auxiliary functional structure 8 only covers the 1 / 6-1 / 2 area of ​​the first bridge body 2 near the free end in this way, so that when the first bridge body 2 is elastically deformed toward the driving electrode 5, the auxiliary functional structure 8 on the first bridge body 2 can share part of the stress and reduce the stress and deformation of the membrane bridge; when the first bridge body 2 rebounds away from the driving electrode 5, the tensile stress of the auxiliary functional structure 8 on the first bridge body 2 assists the first bridge body 2 to return to the initial position. At the same time, since the auxiliary functional structure 8 covers a small area in the embodiment of the present disclosure, the manufacturing cost is reduced.

[0045] Similarly, in some embodiments, the auxiliary functional structure 8 is disposed on the first bridge body 2, and the orthographic projection of the auxiliary functional structure 8 overlaps with the orthographic projection of the first bridge body 2. That is, the auxiliary functional structure 8 completely covers the side of the first bridge body 2 close to the driving electrode 5, or Figure 4 As shown, the auxiliary functional structure 8 completely covers the side away from the driving electrode 5. In this way, the preparation process of the auxiliary functional structure 8 is relatively simple.

[0046] In some embodiments, Figure 5As shown, when the membrane bridge includes only one connecting arm 11, the distance from the point on the first bridge body 2 close to the connecting arm 11 to the substrate 1 is smaller than the distance from the point on the membrane bridge far from the bridge arm to the substrate 1. In the disclosed embodiment, since the MEMS switch completes the switch by elastically deforming the first bridge body 2 to contact the convex structure 9, when the distance from the point on the first bridge body 2 close to the connecting arm 11 to the substrate 1 is smaller than the distance from the point on the membrane bridge far from the bridge arm to the substrate 1, that is, when the structure of the first bridge body 2 bends upward away from the substrate 1, it is easy to increase the contact area when the membrane bridge contacts the convex structure 9, which helps to avoid the occurrence of poor contact of the MEMS switch. In some embodiments, as Figure 6 As shown, the MEMS switch also includes a second bridge body 201 arranged on the side of the first bridge body 2 away from the substrate 1, and the auxiliary function structure 8 is arranged between the first bridge body 2 and the second bridge body 201. In the embodiment of the present disclosure, the first bridge body 2, the auxiliary function structure 8 and the second bridge body 201 form a three-layer stacked structure away from the substrate 1. In this way, the auxiliary function structure 8 and the membrane bridge are more closely combined. When the first bridge body 2 is elastically deformed toward the driving electrode 5, the auxiliary function structure 8 on the first bridge body 2 can better share the stress of the membrane bridge and reduce the stress and deformation of the membrane bridge; when the first bridge body 2 rebounds away from the driving electrode 5, the tensile stress of the auxiliary function structure 8 on the first bridge body 2 can better assist the first bridge body 2 to return to the initial position. In some embodiments, in order to ensure that the auxiliary function structure 8 is in the stress structure position of the membrane bridge and to better provide compressive stress for the membrane bridge, the thickness of the first bridge body 2 is greater than the thickness of the second bridge body 201.

[0047] In some embodiments, Figure 7 As shown, the membrane bridge in the MEMS switch includes two connecting arms 11. Figure 7The MEMS switch of the embodiment of the present disclosure includes a substrate 1 and a second insulating layer 7 arranged on the substrate 1. The second insulating layer 7 is used to reduce the roughness of the substrate 1, reduce the electromagnetic loss of the substrate 1, and increase the adhesion of the film layer arranged on the second insulating layer 7. A driving electrode 5 and a first insulating layer 6 are sequentially arranged on the side of the second insulating layer 7 away from the substrate 1. The first insulating layer 6 completely covers the surface of the driving electrode 5 to protect the driving electrode 5. A first connecting arm and a second connecting arm are arranged on the side of the first insulating layer 6 away from the substrate 1. The first connecting arm and the second connecting arm support the film bridge so that there is a certain space between the first bridge body 2 and the driving electrode 5. An auxiliary functional structure 8 is arranged on the first bridge body 2, and the elastic modulus of the auxiliary functional structure 8 is greater than the elastic modulus of the first bridge body 2. Under the drive of the driving electrode 5, the first bridge body 2 undergoes elastic deformation toward the driving electrode 5, the gap between the driving electrode 5 and the first bridge body 2 is reduced, and the capacitance value between the driving electrode 5 and the first bridge body 2 is changed, so as to realize the opening and closing of the MEMS switch to the electrical signal. At the same time, in the embodiment of the present disclosure, since an auxiliary functional structure 8 is provided, when the first bridge body 2 undergoes elastic deformation toward the driving electrode 5, the auxiliary functional structure 8 on the first bridge body 2 can share part of the stress and reduce the stress and deformation of the membrane bridge; when the first bridge body 2 rebounds away from the driving electrode 5, the tensile stress of the auxiliary functional structure 8 on the first bridge body 2 assists the first bridge body 2 to return to its initial position.

[0048] Specifically, the first connecting arm and the second connecting arm are respectively connected to the two ground wires in the coplanar waveguide CPW. When no effective voltage is loaded on the driving electrode 5, the capacitance between the membrane bridge and the signal wire is very small, the input RF / microwave signal can be successfully transmitted to the output port, and the MEMS switch is in the on state; when an effective voltage is loaded on the driving electrode 5, the electric field between the first bridge body 2 and the driving electrode 5 causes the first bridge body 2 to undergo elastic deformation, and the gap between the first bridge body 2 and the driving electrode 5 is reduced, and finally contacts the first insulating layer 6. At this time, a relatively large capacitance is formed between the signal line and the ground wire, which can reflect the input RF / microwave signal of a specific frequency band, and the MEMS switch is in the off state.

[0049] Accordingly, an embodiment of the present disclosure further provides a method for preparing the above-mentioned MEMS switch, the manufacturing method comprising:

[0050] A base substrate 1 is provided. A driving electrode 5 is formed on the base substrate 1. A first insulating layer 6 is formed on the side of the driving electrode 5 facing away from the base substrate 1, and the first insulating layer 6 at least covers the side of the driving electrode 5 facing away from the base substrate 1. A sacrificial layer 10 having at least one via hole is formed on the first insulating layer 6, and a membrane bridge is formed on the sacrificial layer 10 on the side facing away from the base substrate 1. The steps of forming the membrane bridge include: forming a connecting arm 11 in the via hole and forming a first bridge body 2 on the side of the sacrificial layer 10 facing away from the base substrate 1, and forming an auxiliary functional structure 8 on the first bridge body 2; the elastic modulus of the auxiliary functional structure 8 is greater than the elastic modulus of the first bridge body 2. The sacrificial layer 10 is removed by a sacrificial layer 10 release process.

[0051] In order to clarify the preparation method in the embodiment of the present disclosure, the preparation method of the MEMS switch in the embodiment of the present disclosure is described below with reference to the accompanying drawings and specific embodiments. Figure 8 A flow chart of a method for manufacturing a MEMS switch provided in an embodiment of the present disclosure, the manufacturing method comprising:

[0052] S10, providing a substrate 1.

[0053] In some embodiments, the substrate 1 may be a silicon substrate, a glass substrate or high-resistance silicon, etc. The specific steps of step S10 may be: selecting a substrate 1 with a thickness of 0.2 mm-1 mm, and performing ultrasonic cleaning on the substrate 1 to remove impurities on the surface of the substrate 1. Specifically, the ultrasonic cleaning process is to soak the substrate 1 in deionized water, ethanol and isopropanol in turn, and perform ultrasonic (oscillation) cleaning, and the cleaning time may be 20 minutes.

[0054] S11 , forming a second insulating layer 7 on the base substrate 1 .

[0055] In some embodiments, Fig. 9 As shown, a second insulating layer 7 is formed on the surface of the substrate 1 by a method such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). In some embodiments, the material of the second insulating layer 7 is an inorganic insulating material. For example, the second insulating layer 7 can be an inorganic insulating layer formed by silicon nitride (SiNx), or an inorganic insulating layer formed by silicon oxide (SiO2), or a laminated composite film layer of a SiNx inorganic insulating layer and a SiO2 inorganic insulating layer. The thickness of the second insulating layer 7 can be 0.5 microns to 3 microns, which is used to reduce the roughness of the substrate 1, reduce the electromagnetic loss of the substrate 1, and increase the adhesion when preparing subsequent film layers.

[0056] S12 , forming a second convex substructure 902 on the second insulating layer 7 .

[0057] In some embodiments, Fig.10 As shown, a third insulating film can be formed on the substrate 1 by PVD or CVD, and then the third insulating film is exposed, developed, and etched to form the second convex substructure 902. The material of the third insulating film can be silicon nitride, etc., and its thickness can be 0.3 microns to 2 microns.

[0058] S13 , forming a driving electrode 5 on the second insulating layer 7 .

[0059] In some embodiments, Fig.11 As shown, step S13 may specifically be as follows:

[0060] (1) Growth of seed layer: A first metal material is deposited on the second insulating layer 7 by magnetron sputtering as a seed layer. In some embodiments, the first metal material includes but is not limited to at least one of copper (Cu), aluminum (Al), molybdenum (Mo), and silver (Ag).

[0061] (2) Forming the driving electrode 5: The driving electrode 5 is prepared by electroplating metal traces, spinning photoresist, exposing and etching patterns on the seed layer. The material of the driving electrode 5 includes but is not limited to at least one of copper (Cu), aluminum (Al), tungsten (W), and silver (Ag). The thickness of the driving electrode 5 can be 2 microns to 5 microns.

[0062] S14 , forming a first insulating layer 6 on the second insulating layer 7 .

[0063] In some embodiments, Fig.12 As shown, the first insulating layer 6 completely covers the drive electrode 5, and in this way protects the drive electrode 5 from physical damage or water and oxygen erosion. In step S14, the first insulating layer 6 is formed on the surface of the substrate 1 by a method such as PVD or CVD. In some embodiments, the material of the first insulating layer 6 is an inorganic insulating material. For example: the first insulating layer 6 can be an inorganic insulating layer formed by silicon nitride (SiNx), or an inorganic insulating layer formed by silicon oxide (SiO2), or a plurality of stacked composite film layers of SiNx inorganic insulating layers and SiO2 inorganic insulating layers. The thickness of the second insulating layer 7 can be 0.5 microns to 2 microns.

[0064] S15 , forming an anchor point 4 and a first convex substructure 901 on the surface of the first insulating layer 6 facing away from the substrate 1 .

[0065] In step S15, Fig.13As shown, a seed layer can be formed, and processes such as electroplating metal wiring, spin coating photoresist, and exposing and etching patterns can be used on the seed layer to complete the preparation of the anchor point 4 and the first convex substructure 901. Among them, the specific preparation method and materials of the anchor point 4 and the first convex substructure 901 can be the same as the method for preparing the drive electrode 5, which will not be repeated here. In some embodiments, the thickness of the anchor point 4 and the first convex substructure 901 can be 2 microns-10 microns.

[0066] S16 , forming a sacrificial layer 10 on the side of the anchor point 4 and the first convex substructure 901 facing away from the substrate 1 , and forming a first connecting via on the sacrificial layer 10 .

[0067] In some embodiments, the material of the sacrificial layer 10 may be an organic material, such as polyimide (PI), photoresist, etc., or an inorganic material, such as polysilicon, phosphosilicate glass, etc. Fig.14 As shown, the sacrificial layer 10 of organic material can be prepared by spin coating, and the rotation speed of the spin coating tool and the total amount of solution added can be precisely controlled during the preparation process to achieve high flatness of the surface of the sacrificial layer 10. The sacrificial layer 10 of inorganic material can be prepared by CVD or PVD method, and the thickness of the film layer can be precisely controlled during the preparation process to achieve high flatness of the entire surface of the insulating substrate 1. The thickness of the sacrificial layer 10 can be 0.5 microns to 5 microns.

[0068] In some embodiments, a first connecting via is formed on the sacrificial layer 10 by etching or photolithography, and the first connecting via and the orthographic projection of the anchor point 4 on the base substrate 1 at least partially overlap.

[0069] S17, forming the support portion 3 and the first bridge body 2.

[0070] In some embodiments, Fig.15 As shown, a first bridge body 2 is formed on the surface of the sacrificial layer 10 facing away from the substrate 1, and the orthographic projections of the first bridge body 2, the driving electrode 5 and the first sub-convex structure 9 on the substrate 1 at least partially overlap. A support portion 3 is formed in the first connecting via, and the support portion 3 is electrically connected to the anchor point 4. The support portion 3 and the anchor point 4 constitute the cantilever beam structure of the MEMS switch. Specifically, in step S17, a seed layer can be formed, and processes such as electroplating metal wiring, spin coating photoresist, and exposing and etching patterns can be used on the seed layer to complete the preparation of the support portion 3 and the first bridge body 2. Among them, the specific preparation method and materials of the support portion 3 and the first bridge body 2 can be the same as the method for preparing the driving electrode 5, which will not be repeated here. In some embodiments, the thickness of the support portion 3 and the first bridge body 2 can be 3 microns-10 microns.

[0071] S18 , forming an auxiliary functional structure 8 on the first bridge body 2 .

[0072] In some embodiments, the auxiliary functional structure 8 can be formed on the side of the first bridge body 2 facing away from the substrate 1 by CVD, mechanical transfer or orientation growth method. Fig.16 As shown, the orthographic projections of the auxiliary functional structure 8 and the first bridge body 2 on the substrate 1 completely overlap, that is, the auxiliary functional structure 8 completely covers the first bridge body 2. In some embodiments, the orthographic projection of the auxiliary functional structure on the substrate includes the first edge 16, the second edge 18, the third edge 17 and the fourth edge 19, and the orthographic projection of the first bridge body on the substrate includes the fifth edge 12, the sixth edge 14, the seventh edge 13 and the eighth edge 15; the first edge 16 and the third edge 17 are arranged oppositely, the second edge 18 and the fourth edge 19 are arranged oppositely, the fifth edge 12 and the seventh edge 13 are arranged oppositely, and the sixth edge 14 and the eighth edge 15 are arranged oppositely; the first edge 16, the second edge 18 and the third edge 17 overlap with the fifth edge 12, the sixth edge 14 and the seventh edge 13 respectively; the distance between the fourth edge 19 and the eighth edge 15 is 1 / 6-1 / 2 of the length of the fifth edge 12 or the seventh edge 13. That is, the auxiliary functional structure 8 only partially covers the first bridge body 2.

[0073] It should be noted that, in some embodiments, the order of step S17 and step S18 can be interchanged. Figure 4 As shown, the auxiliary functional structure 8 is formed on a side of the first bridge body 2 close to the substrate 1 .

[0074] S19, removing the sacrificial layer 10, so that the first bridge body 2 is suspended on the side of the driving electrode 5 away from the substrate 1, the anchor point 4 and the support part 3 form a bridge arm, and the bridge arm and the first bridge body 2 form a cantilever beam structure.

[0075] In step 19 , the sacrificial layer 10 may be removed by plasma etching or acid-base etching, depending on the material of the sacrificial layer 10 .

[0076] In some embodiments, the surface of the sacrificial layer 10 can be processed or the internal stress generated during the thin film deposition can be used to make the first bridge body 2 warp in a direction away from the substrate 1, so as to form a Figure 4 The MEMS switch shown.

[0077] The preparation of the MEMS switch is now completed.

[0078] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A micro-electromechanical system switch, characterized in that: include: substrate substrate; A membrane bridge, comprising a first bridge body disposed opposite to the substrate base, and at least one connecting arm disposed on the substrate base for supporting the first bridge body; A driving electrode, arranged on a side of the first bridge body close to the substrate and spaced apart from the first bridge body; a first insulating layer, covering at least a surface of the driving electrode close to the first bridge body; an auxiliary function structure, which is at least arranged on the first bridge body, and the elastic modulus of the auxiliary function structure is greater than the elastic modulus of the first bridge body; A convex structure, wherein the convex structure is a conductive structure; The orthographic projections of the convex structure and the membrane bridge on the substrate at least partially overlap; When the membrane bridge includes only one connecting arm, the distance from a point on the first bridge body close to the connecting arm to the substrate is smaller than the distance from a point on the membrane bridge far from the connecting arm to the substrate; wherein, The orthographic projection of the auxiliary functional structure on the substrate includes a first side, a second side, a third side and a fourth side, and the orthographic projection of the first bridge body on the substrate includes a fifth side, a sixth side, a seventh side and an eighth side; the first side and the third side are arranged opposite to each other, the second side and the fourth side are arranged opposite to each other, the fifth side and the seventh side are arranged opposite to each other, and the sixth side and the eighth side are arranged opposite to each other; The first side, the second side and the third side coincide with the fifth side, the sixth side and the seventh side respectively; The distance between the fourth side and the eighth side is 1 / 6-1 / 2 of the length of the first side or the third side; The membrane bridge also includes a second bridge body arranged away from the first bridge body; The auxiliary functional structure is arranged between the first bridge body and the second bridge body; The thickness of the first bridge body is greater than the thickness of the second bridge body.

2. The MEMS switch according to claim 1, characterized in that: The auxiliary functional structure is attached to a side of the first bridge body facing away from the driving electrode.

3. The MEMS switch according to claim 1, characterized in that: The auxiliary functional structure is attached to a side of the first bridge body close to the driving electrode.

4. The MEMS switch according to any one of claims 1 to 3, characterized in that: The auxiliary functional structure is disposed on the first bridge body, and an orthographic projection of the auxiliary functional structure overlaps with an orthographic projection of the first bridge body.

5. The MEMS switch according to claim 1, characterized in that: The convex structure includes a first convex substructure and a second convex substructure; the first convex substructure is arranged on a side of the second convex substructure away from the substrate; and the first convex substructure is a conductive structure.

6. The MEMS switch according to any one of claims 1 to 3, characterized in that: The membrane bridge includes two connecting arms.

7. The MEMS switch according to claim 1, characterized in that: When the membrane bridge includes only one connecting arm, the connecting arm includes a supporting portion and an anchor point; the anchor point is arranged between the substrate and the supporting portion, and the anchor point and the supporting portion have at least partially overlapped orthographic projections on the substrate.

8. The MEMS switch according to claim 1, characterized in that: The material of the auxiliary functional structure includes graphene.

9. A method for preparing a micro-electromechanical system switch, characterized in that: include: Providing a substrate; forming a driving electrode on the base substrate; forming a first insulating layer on a side of the driving electrode facing away from the substrate; The first insulating layer at least covers a side of the driving electrode away from the substrate; forming a sacrificial layer having at least one via hole on the first insulating layer; forming a membrane bridge on the sacrificial layer at a side away from the substrate; The step of forming the membrane bridge includes: forming a connecting arm in the via hole and forming a first bridge body on a side of the sacrificial layer away from the substrate; forming an auxiliary functional structure on the first bridge body; the elastic modulus of the auxiliary functional structure is greater than the elastic modulus of the first bridge body; The sacrificial layer is removed by a sacrificial layer release process, wherein: When the membrane bridge includes only one connecting arm, the distance from a point on the first bridge body close to the connecting arm to the substrate is smaller than the distance from a point on the membrane bridge far from the connecting arm to the substrate; wherein, The orthographic projection of the auxiliary functional structure on the substrate includes a first side, a second side, a third side and a fourth side, and the orthographic projection of the first bridge body on the substrate includes a fifth side, a sixth side, a seventh side and an eighth side; the first side and the third side are arranged opposite to each other, the second side and the fourth side are arranged opposite to each other, the fifth side and the seventh side are arranged opposite to each other, and the sixth side and the eighth side are arranged opposite to each other; The first side, the second side and the third side coincide with the fifth side, the sixth side and the seventh side respectively; The distance between the fourth side and the eighth side is 1 / 6-1 / 2 of the length of the first side or the third side; The step of forming a membrane bridge also includes: A second bridge body is formed on the auxiliary functional structure at a side away from the substrate, wherein the auxiliary functional structure is arranged between the first bridge body and the second bridge body; and the thickness of the first bridge body is greater than that of the second bridge body.

10. The preparation method according to claim 9, characterized in that: The steps of forming the auxiliary function structure include: The auxiliary functional structure is formed on a side of the first bridge body facing away from the substrate.

11. The preparation method according to claim 9, characterized in that: The steps of forming the auxiliary function structure include: forming the auxiliary functional structure on the sacrificial layer at a side away from the substrate; The first bridge is formed on a side of the auxiliary functional structure away from the substrate.

12. The preparation method according to claim 9, characterized in that: Also includes: Before forming the driving electrode, forming a second insulating layer on the base substrate; Before forming the first insulating layer, forming a second convex substructure on the second insulating layer; Before forming the sacrificial layer, forming a first convex substructure on the first insulating layer at a side away from the second convex substructure; the first convex substructure is a conductive structure; The orthographic projections of the first bridge, the first convex substructure, and the second convex substructure on the substrate at least partially overlap.

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