Micromechanical switch and preparation method thereof

Abstract

The invention discloses a micro-mechanical switch and a preparation method thereof, and belongs to the technical field of communication. The micromechanical switch comprises: a substrate (1); the signal electrode (21), the first reference electrode (22) and the second reference electrode (23) are arranged on the substrate (1), and the first reference electrode (22) and the second reference electrode (23) are located on the two sides of the extending direction of the signal electrode (21) respectively; the interlayer dielectric layer (4) at least covers one side, deviating from the substrate (1), of the signal electrode (21); the film bridge structure (3) is arranged on one side, deviating from the substrate (1), of the interlayer dielectric layer (4); wherein the membrane bridge structure (3) comprises a bridge floor (31) and at least one supporting part (32, 33), and the supporting part (32, 33) is connected with the end part of the bridge floor (31); a first gap (d1) is formed between the bridge surface (31) and the interlayer dielectric layer (4) on the signal electrode (21); the orthographic projection of the connection position of the supporting part (32, 33) and the end part of the bridge surface (31) on the substrate (1) has a first width (W1) in a first direction, and the first direction is the direction in which the first reference electrode (22) points to the second reference electrode (23); the first width (W1) is not less than half of the first gap (d1).

Description

Micromechanical switch and preparation method thereof Technical Field

[0001] The present disclosure belongs to the field of communication technology, and particularly relates to a micromechanical switch and a preparation method thereof. Background Art

[0002] RF MEMS (Radio Frequency Micromachined Switch) is a new technology that combines MEMS (Micro-Electro-Mechanical System) and RF (Radio Frequency) technologies. MEMS devices have the advantages of small size, easy integration, low power consumption, and high reliability, and can replace semiconductor devices in traditional wireless communication systems. RF MEMS can not only be applied to circuits in the form of devices, such as MEMS switches, MEMS capacitors, and MEMS resonators; RF MEMS can also integrate single devices into the same chip components and application systems, such as filters, voltage-controlled oscillators, phase shifters, phased array radar antennas, etc., which greatly reduces the size of traditional devices, reduces power consumption, and improves system performance. As one of the important components in RF MEMS, the performance of RF MEMS switches has an increasingly profound impact on microelectromechanical systems.

[0003] Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art and provides a micromechanical switch and a method for preparing the same.

[0005] An embodiment of the present disclosure provides a micromechanical switch, comprising:

[0006] substrate;

[0007] A signal electrode, a first reference electrode and a second reference electrode are provided on the base substrate, and the first reference electrode and the second reference electrode are respectively located on both sides of the extension direction of the signal electrode;

[0008] an interlayer dielectric layer, covering at least a side of the signal electrode facing away from the base substrate;

[0009] The membrane bridge structure is arranged on the side of the interlayer dielectric layer away from the substrate; wherein,

[0010] The membrane bridge structure includes a bridge deck and at least one supporting portion, wherein the supporting portion is connected to the end of the bridge deck; a first gap is provided between the bridge deck and the interlayer dielectric layer on the signal electrode; the connection position of the supporting portion and the end of the bridge deck is projected onto the substrate, and the width in the first direction is a first width, wherein the first direction is the direction in which the first reference electrode points to the second reference electrode; the first width is not less than half of the first gap.

[0011] Wherein, the thickness of the bridge deck of the membrane bridge structure is not less than the first gap.

[0012] Wherein, the thickness of the support portion and the thickness of the bridge deck are both equal to the first gap.

[0013] It also includes a reinforcement piece, which is arranged on the side of the membrane bridge structure away from the base substrate and is located at the connection position between the support part and the bridge deck; the bridge deck and the support part both overlap with the positive projection part of the reinforcement piece on the base substrate.

[0014] Wherein, the at least one supporting portion includes a first supporting portion and / or a second supporting portion; the end portion of the bridge deck includes a first end portion and a second end portion;

[0015] When the supporting portion includes a first supporting portion, the first supporting portion is connected to the first end portion of the bridge deck, the first supporting portion is located on a side of the first reference electrode facing away from the substrate, and at least partially overlaps with an orthographic projection of the first reference electrode on the substrate; the reinforcing member includes a first reinforcing member, the first reinforcing member is located at a connection position between the first supporting portion and the first end portion; the first reinforcing member includes a first reinforcement portion, a second reinforcement portion, and a first connecting portion connecting the first reinforcement portion and the second reinforcement portion; the first reinforcement portion is located on a side of the first end portion facing away from the substrate, and the second reinforcement portion is located on a side of the first supporting portion facing away from the substrate; the orthographic projection of an end of the first reinforcement portion away from the first connection portion on the substrate is located between the orthographic projections of the first reference electrode and the signal electrode on the substrate;

[0016] When the supporting portion includes a second supporting portion, the second supporting portion is connected to the second end portion of the bridge deck, the second supporting portion is located on the side of the second reference electrode facing away from the substrate, and at least partially overlaps with the orthographic projection of the second reference electrode on the substrate; the reinforcing member includes a second reinforcing member, and the second reinforcing member is located at the connection position between the second supporting portion and the second end; the second reinforcing member includes a third reinforcing portion, a fourth reinforcing portion, and a second connecting portion connecting the third reinforcing portion and the fourth reinforcing portion; the third reinforcing portion is located on the side of the second end facing away from the substrate, and the fourth reinforcing portion is located on the side of the second supporting portion facing away from the substrate; the orthographic projection of one end of the third reinforcing portion away from the second connecting portion on the substrate is located between the orthographic projection of the second reference electrode and the signal electrode on the substrate.

[0017] When the micromechanical switch includes a first reinforcement member, the first reinforcement member has a first side surface disposed opposite to the first connecting portion, the first side surface is a concave arc surface, or a dihedral angle formed by the first side surface and the plane where the bridge surface is located is an obtuse angle;

[0018] When the micromechanical switch includes a second reinforcement member, the third reinforcement portion has a third side surface arranged opposite to the second connection portion, the third side surface is a concave arc surface, or the dihedral angle formed by the third side surface and the plane where the bridge surface is located is an obtuse angle.

[0019] Wherein, the membrane bridge structure and the reinforcement are made of the same material.

[0020] Wherein, the membrane bridge structure and the reinforcement are an integrally formed structure.

[0021] Wherein, a protective layer is provided between the bridge deck and the reinforcement member.

[0022] Wherein, the base substrate is a glass substrate.

[0023] The present disclosure provides a method for manufacturing a micromechanical switch, which includes:

[0024] providing a substrate;

[0025] forming a signal electrode, a first reference electrode, and a second reference electrode on the base substrate; wherein the first reference electrode and the second reference electrode are located on both sides of an extending direction of the signal electrode;

[0026] forming an interlayer dielectric layer on a side of the layer where the signal electrode, the first reference electrode and the second reference electrode are located away from the base substrate, wherein the interlayer dielectric layer at least covers the side of the signal electrode away from the base substrate;

[0027] A film bridge structure is formed on the side of the interlayer dielectric layer away from the substrate; wherein,

[0028] The membrane bridge structure includes a bridge deck and at least one supporting portion, wherein the supporting portion is connected to the end of the bridge deck; a first gap is provided between the bridge deck and the interlayer dielectric layer on the signal electrode; the connection position of the supporting portion and the end of the bridge deck is projected onto the substrate, and the width in the first direction is a first width, wherein the first direction is the direction in which the first reference electrode points to the second reference electrode; the first width is not less than the first gap.

[0029] Wherein, the thickness of the bridge deck of the membrane bridge structure is not less than the first gap.

[0030] The thickness of the supporting parts is equal to the thickness of the bridge deck structure, and the thickness of the bridge deck structure is equal to the first gap.

[0031] The step of forming a membrane bridge structure on a side of the interlayer dielectric layer away from the substrate includes:

[0032] forming a sacrificial layer on a side of the interlayer dielectric layer facing away from the base substrate, wherein the orthographic projection of the sacrificial layer on the base substrate covers the orthographic projection of the signal electrode on the base substrate, the gap between the signal electrode and the first reference electrode, and the gap between the signal electrode and the second reference electrode;

[0033] A first conductive film is formed on the side of the sacrificial layer away from the base substrate as a first seed layer, and the first seed layer is electroplated to form a first conductive layer. The first conductive layer is patterned to form a pattern including a membrane bridge structure, and the sacrificial layer is released.

[0034] Wherein, the material of the sacrificial layer is photoresist or polyimide.

[0035] Wherein, the preparation method further comprises:

[0036] A reinforcement is formed on the side of the membrane bridge structure facing away from the substrate; the reinforcement is located at the connection position between the support portion and the bridge deck; the orthographic projection of the reinforcement on the substrate at least covers the orthographic projection of the connection position between the support portion and the bridge deck on the substrate.

[0037] Wherein, the at least one supporting portion includes a first supporting portion and / or a second supporting portion; the end portion of the bridge deck includes a first end portion and a second end portion;

[0038] When the supporting portion includes a first supporting portion, the first supporting portion is connected to the first end portion of the bridge deck, the first supporting portion is located on a side of the first reference electrode facing away from the substrate, and at least partially overlaps with an orthographic projection of the first reference electrode on the substrate; the reinforcing member includes a first reinforcing member, the first reinforcing member is located at a connection position between the first supporting portion and the first end portion; the first reinforcing member includes a first reinforcement portion, a second reinforcement portion, and a first connecting portion connecting the first reinforcement portion and the second reinforcement portion; the first reinforcement portion is located on a side of the first end portion facing away from the substrate, and the second reinforcement portion is located on a side of the first supporting portion facing away from the substrate; the orthographic projection of an end of the first reinforcement portion away from the first connection portion on the substrate is located between the orthographic projections of the first reference electrode and the signal electrode on the substrate;

[0039] When the supporting portion includes a second supporting portion, the second supporting portion is connected to the second end portion of the bridge deck, the second supporting portion is located on the side of the second reference electrode facing away from the substrate, and at least partially overlaps with the orthographic projection of the second reference electrode on the substrate; the reinforcing member includes a second reinforcing member, and the second reinforcing member is located at the connection position between the second supporting portion and the second end; the second reinforcing member includes a third reinforcing portion, a fourth reinforcing portion, and a second connecting portion connecting the third reinforcing portion and the fourth reinforcing portion; the third reinforcing portion is located on the side of the second end facing away from the substrate, and the fourth reinforcing portion is located on the side of the second supporting portion facing away from the substrate; the orthographic projection of one end of the third reinforcing portion away from the second connecting portion on the substrate is located between the orthographic projection of the second reference electrode and the signal electrode on the substrate.

[0040] When the micromechanical switch includes a first reinforcement member, the first reinforcement member has a first side surface disposed opposite to the first connecting portion, the first side surface is a concave arc surface, or a dihedral angle formed by the first side surface and the plane where the bridge surface is located is an obtuse angle;

[0041] When the micromechanical switch includes a second reinforcement member, the third reinforcement portion has a third side surface arranged opposite to the second connection portion, the third side surface is a concave arc surface, or the dihedral angle formed by the third side surface and the plane where the bridge surface is located is an obtuse angle.

[0042] Wherein, the reinforcement and the membrane bridge structure are prepared in a single patterning process.

[0043] Wherein, the preparation method further comprises:

[0044] Before forming the reinforcing member, a protective layer is formed on a side of the bridge surface of the membrane bridge structure facing away from the substrate.

[0045] Wherein, the base substrate is a glass substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a cross-sectional view of an exemplary micromechanical (MEMS) switch.

[0047] FIG. 2 is a schematic diagram of the bridge deck collapse of the MEMS switch shown in FIG. 1 .

[0048] FIG3 is a cross-sectional view of a MEMS switch according to an embodiment of the present disclosure.

[0049] FIG4 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure.

[0050] FIG5 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure.

[0051] FIG6 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure.

[0052] FIG. 7 is a schematic diagram illustrating the connection position between the bridge surface and the first reinforcement member of the MEMS switch according to an embodiment of the present disclosure.

[0053] FIG8 is another schematic diagram of the connection position between the bridge deck and the first reinforcement member of the MEMS switch according to an embodiment of the present disclosure.

[0054] FIG9 is a flow chart of Example 1 of a method for manufacturing a MEMS switch according to an embodiment of the present disclosure.

[0055] FIG10 is a flow chart of Example 2 of the method for manufacturing a MEMS switch according to an embodiment of the present disclosure.

[0056] FIG11 is a flow chart of Example 3 of the method for manufacturing a MEMS switch according to an embodiment of the present disclosure.

[0057] FIG12 is a flow chart of Example 4 of the method for preparing a MEMS switch according to an embodiment of the present disclosure.

[0058] FIG13 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0059] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0060] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by people with ordinary skills in the field to which this disclosure belongs. The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" do not indicate a quantity limitation, but rather indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may 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 object being described changes, the relative positional relationship may also change accordingly.

[0061] FIG1 is a cross-sectional view of an exemplary micromechanical (MEMS) switch. As shown in FIG1 , the MEMS switch includes a substrate 1, a signal electrode 21, a first reference electrode 22, a second reference electrode 23, an interlayer dielectric layer 4, and a membrane bridge structure 3. The signal electrode 21, the first reference electrode 22, and the second reference electrode 23 are all disposed on the substrate 1. The signal electrode 21, the first reference electrode 22, and the second reference electrode 23 are disposed on the same layer. The first reference electrode 22 and the second reference electrode 23 are located on either side of the extension direction of the signal electrode 21. The signal electrode 21, the first reference electrode 22, and the second reference electrode 23 form a coplanar waveguide (CPW) transmission line. The interlayer dielectric layer 4 covers at least the side of the signal electrode 21 facing away from the substrate 1 to insulate the signal electrode 21 from the other electrodes. The membrane bridge structure 3 is arranged on the side of the interlayer dielectric layer 4 away from the base substrate 1, and the first support part 32 and the second support part 33 of the membrane bridge structure 3 are respectively located on the first reference electrode 22 and the second reference electrode 23. There is a first gap d1 between the bridge surface 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4 on the signal electrode 21.

[0062] In this structure, the interlayer dielectric layer 4 only covers the signal electrode 21 and does not cover the first reference electrode 22 and the second reference electrode 23. The first support portion 32 and the second support portion 33 of the membrane bridge structure 3 are respectively arranged on the first reference electrode 22 and the second reference electrode 23. Therefore, when a DC bias voltage is applied to the first reference electrode 22 and the second reference electrode 23, the membrane bridge structure 3 is loaded with the same DC bias voltage as the first reference electrode 22 and the second reference electrode 23. For ease of control, the first reference electrode 22 and the second reference electrode 23 can be loaded with a ground potential, that is, the potential of the first reference electrode 22 and the second reference electrode 23 is the reference ground. Of course, the interlayer dielectric layer 4 can also cover the first reference electrode 22 and the second reference electrode 23 while covering the signal electrode 21. In this case, it is necessary to lay out a signal line in the membrane bridge structure 3 to load it with voltage. However, in the disclosed embodiment, for ease of control and to achieve device miniaturization, it is preferred that the interlayer dielectric layer 4 only covers the signal electrode 21, and the membrane bridge structure 3 is loaded with the same DC bias voltage as the first reference electrode 22 and the second reference electrode 23.

[0063] The working principle of the above-mentioned MEMS switch is as follows: when the corresponding DC bias voltage is loaded on the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 respectively, the potential of the membrane bridge structure 3 is equal to that of the first reference electrode 22 and the second reference electrode 23. At this time, the electrostatic force generated between the membrane bridge structure 3 and the signal electrode 21 will cause the bridge surface 31 of the membrane bridge structure 3 to bend and pull down, and finally contact the interlayer dielectric layer 4 on the signal electrode 21. Since the distance between the bridge surface 31 of the membrane bridge structure 3 and the signal electrode 21 is large in the initial state (that is, the first gap d1), the capacitance is very small, and the radio frequency signal will be transmitted along the signal electrode 21. As the bridge surface 31 structure approaches the signal electrode 21, the capacitance increases accordingly, and the radio frequency signal will be coupled to the membrane bridge structure 3 to realize the closure of the MEMS switch. On the contrary, when the DC bias voltage loaded on the signal electrode, the first reference electrode 22 and the second reference electrode 23 is removed, the bridge deck 31 of the membrane bridge structure 3 returns to its initial position due to its own elastic restoring force, the distance between the bridge deck 31 and the signal electrode 21 becomes larger, and the capacitance decreases accordingly. The RF signal will no longer be coupled to the membrane bridge structure 3, and will continue to be transmitted along the signal electrode 21, thereby realizing the disconnection of the MEMS switch.

[0064] The preparation of the membrane bridge in a MEMS switch typically involves forming a sacrificial layer 8 on a substrate 1 having a signal electrode 21, a first reference electrode 22, a second reference electrode 23, and an interlayer dielectric layer 4. A conductive film is then formed on the sacrificial layer 8 facing away from the substrate 1 to form a membrane bridge structure 3. Finally, the sacrificial layer 8 is released. FIG2 is a schematic diagram of the collapse of the bridge surface 31 of the MEMS switch shown in FIG1 . As shown in FIG2 , the inventors discovered that because the conductive film forming the membrane bridge structure 3 is relatively thin, the first support portion 32 and the second support portion 33 are relatively thin. During the release of the sacrificial layer 8, the bridge surface 31 of the membrane bridge structure 3 can easily collapse due to its own gravity and electrostatic force, resulting in an extremely low yield rate.

[0065] In response to the above problems, the embodiments of the present disclosure provide the following technical solutions.

[0066] Before describing the MEMS switch of the embodiment of the present disclosure, it should be noted that the MEMS switch of the embodiment of the present disclosure may be a membrane bridge structure 3, which may be a double-arm bridge or a single-arm bridge. For the convenience of description, the two support parts in the double-arm bridge are respectively referred to as the first support part 32 and the second support part 33, and the first support part 32 corresponds to the position of the first reference electrode 22, and the second support part 33 corresponds to the position of the second reference electrode 23. In addition, the biggest difference between the single-arm bridge and the double-arm bridge is that the single-arm bridge has only one support part. In the embodiment of the present disclosure, the support part of the single-arm bridge corresponds to the position of the first reference electrode 22. It should be understood that the support part can also correspond to the position of the second reference electrode. In the following examples, for the convenience of description, the MEMS switch of the embodiment of the present disclosure is described with the membrane bridge structure 3 as a double-arm bridge and a single-arm bridge, respectively.

[0067] First example: Figure 3 is a cross-sectional view of a MEMS switch according to an embodiment of the present disclosure. As shown in Figure 3, the membrane bridge structure 3 of the micromechanical switch is a double-arm bridge. The micromechanical switch may specifically include a substrate 1, a signal electrode 21, a first reference electrode 22, a second reference electrode 23, an interlayer dielectric layer 4, and a membrane bridge structure 3. The signal electrode 21, the first reference electrode 22, and the second reference electrode 23 are all disposed on the substrate 1, and the signal electrode 21, the first reference electrode 22, and the second reference electrode 23 are disposed on the same layer. The first reference electrode 22 and the second reference electrode 23 are located on both sides of the extension direction of the signal electrode 21. The signal electrode 21, the first reference electrode 22, and the second reference electrode 23 form a CPW transmission line. The interlayer dielectric layer 4 covers at least the side of the signal electrode 21 facing away from the substrate 1 to insulate the signal electrode 21 from the other electrodes. The membrane bridge structure 3 is disposed on the side of the interlayer dielectric layer 4 facing away from the substrate 1.

[0068] Among them, the membrane bridge structure 3 includes a bridge deck 31, a first support part 32 and a second support part 33; the bridge deck 31 has a first end and a second end, the first end is connected to the first support part 32, and the second end is connected to the second support part 33; the first support part 32 is projected on the substrate 1 on the first reference electrode 22, and the second support part 33 is projected on the substrate 1 on the second reference electrode 23, and there is a first gap d1 between the bridge deck 31 and the interlayer dielectric layer 4 on the signal electrode 21; the width of the overlapping position of the first end and the orthographic projection of the first support part 32 on the substrate 1 in the first direction is the first width W1, and the width of the overlapping position of the second end and the orthographic projection of the second support part 33 on the substrate 1 in the first direction is the second width W2; the first direction is the direction from the first reference electrode 22 to the second reference electrode 23; the first width W1 and the second width W2 are not less than half of the first gap d1.

[0069] In the embodiment of the present disclosure, since the width of the overlapping position of the orthographic projection of the first end portion of the bridge deck 31 and the first support portion 32 on the substrate 1 in the first direction is the first width W1, and the width of the overlapping position of the orthographic projection of the second end portion and the second support portion 33 on the substrate 1 in the first direction is the second width W2; the first width W1 and the second width W2 are both not less than half of the first gap d1, that is, the connection area between the first end portion of the bridge deck 31 and the first support portion 32, and the connection area between the second end portion and the second support portion 33 are both relatively large, the first support portion 32 and the second support portion 33 can provide sufficient support for the bridge deck 31 to avoid the problem of collapse of the bridge deck 31.

[0070] In some examples, the thickness of the bridge deck 31 of the membrane bridge structure 3 is not less than the first gap d1. Furthermore, the thickness of the first support portion 32 and the second support portion 33 are both equal to the thickness d2 of the bridge deck 31 structure, that is, the thickness of both is not less than the first gap d1. Among them, the thickness of the first support portion 32 and the second support portion 33 refers to the thickness of the first support portion 32 and the second support portion 33 in the direction perpendicular to the substrate 1. It can be understood that the first gap d1 is the thickness of the sacrificial layer 8 formed when the membrane bridge structure 3 is formed, that is, the thickness of the bridge deck 31 of the membrane bridge structure 3 is not less than the thickness of the sacrificial layer 8. In this way, the first support portion 32 and the second support portion 33 will not partially protrude and abut the bridge deck 31. The first support portion 32 and the second support portion 33 are both in surface-to-surface contact with the bridge deck 31, which can effectively prevent the collapse of the bridge.

[0071] It should be noted that when forming the membrane bridge structure 3, the thickness of the conductive film forming the membrane bridge structure 3 can be adjusted based on the material stiffness and strength of the conductive film. Preferably, the thickness of the conductive film formed is at least 20% thicker than the thickness of the sacrificial layer 8. Theoretically, a thicker conductive film layer improves the stability of the membrane bridge structure 3. However, considering cost and process implementation, the thickness of the membrane bridge structure 3 needs to be specifically set according to the specific situation.

[0072] In some examples, FIG4 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure. As shown in FIG4 , the MEMS switch according to the embodiment of the present disclosure not only includes the aforementioned structure, but may also include a first reinforcement member 51 and / or a second reinforcement member 52. The drawings of the embodiment of the present disclosure only illustrate a MEMS switch including both the first reinforcement member 51 and the second reinforcement member 52. The first reinforcement member 51 is disposed on the side of the membrane bridge structure 3 facing away from the base substrate 1, and is located at the connection between the first end of the bridge deck 31 and the first support portion 32. The orthographic projection of the first reinforcement member 51 on the base substrate 1 at least covers the orthographic projection of the connection between the first end of the bridge deck 31 and the first support portion 32 on the base substrate 1. The connection between the first end of the bridge deck 31 and the first support portion 32 refers to the overlapping position of the orthographic projections of the first end of the bridge deck 31 and the first support portion 32 on the base substrate 1.

[0073] The second reinforcement 52 is provided on the side of the membrane bridge structure 3 facing away from the base substrate 1, and is located at the connection position between the second end portion and the second support portion 33. The orthographic projection of the second reinforcement 52 on the base substrate 1 at least covers the orthographic projection of the connection position between the second end portion of the bridge deck 31 and the second support portion 33 on the base substrate 1. The connection position between the second end portion of the bridge deck 31 and the second support portion 33 refers to the overlapping position of the orthographic projections of the second end portion of the bridge deck 31 and the second support portion 33 on the base substrate 1. In this case, by adding the first reinforcement 51 and the second reinforcement 52, the stability of the membrane bridge structure 3 is further improved, and the collapse of the bridge deck 31 of the membrane bridge structure 3 due to stress and electrostatic force is avoided.

[0074] Furthermore, the first reinforcement member includes a first reinforcement portion 511, a second reinforcement portion 512, and a first connecting portion 513 connecting the first reinforcement portion 511 and the second reinforcement portion 512. The first reinforcement portion 511 is located on the side of the first end portion facing away from the base substrate 1, and the second reinforcement portion 512 is located on the side of the first support portion 32 facing away from the base substrate 1. The orthographic projection of the end of the first reinforcement portion 511 away from the first connecting portion 513 on the base substrate 1 is located between the orthographic projections of the first reference electrode 22 and the signal electrode 21 on the base substrate 1. In the case of the second reinforcing member 52, the second reinforcing member 52 includes a third reinforcing portion 521, a fourth reinforcing portion 522, and a second connecting portion 523 connecting the third and fourth reinforcing portions 522. The third reinforcing portion 521 is located on the side of the second end facing away from the base substrate 1, and the fourth reinforcing portion 522 is located on the side of the second supporting portion 33 facing away from the base substrate 1. The orthographic projection of the end of the third reinforcing portion 521 away from the second connecting portion 523 on the base substrate 1 is located between the orthographic projections of the second reference electrode 23 and the signal electrode 21 on the base substrate 1. In this case, the orthographic projections of the first and second reinforcing members 51, 52 on the base substrate 1 do not overlap with the orthographic projection of the signal electrode 21 on the base substrate 1.

[0075] Furthermore, Figure 5 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure. As shown in Figure 5 , both the first and second reinforcement members can be integrally formed with the membrane bridge structure 3, meaning that the first and second reinforcement members 51 and 52 can be formed simultaneously with the membrane bridge structure 3. In this case, the thickness of the first and second support portions 32 and 33 can be further increased, thereby providing more stable support for the bridge deck 31 and effectively preventing collapse.

[0076] When the first reinforcement 51 and the second reinforcement 52 are integrally formed with the membrane bridge structure 3, the first reinforcement 51, the second reinforcement 52, and the membrane bridge structure 3 can be formed in a single process. For example, a relatively thick conductive film is sputtered or electroplated on the sacrificial layer 8, and then the central region where the bridge surface 31 is to be formed is etched. This results in the integrally formed first reinforcement 51, the second reinforcement 52, and the membrane bridge structure 3 (please refer to the subsequent preparation method for the specific formation process).

[0077] Of course, the first reinforcement member 51 and the second reinforcement member 52 can also be made of the same material as the membrane bridge structure 3. In this case, the first reinforcement member 51 and the second reinforcement member 52 can be manufactured using a single process, and the membrane bridge structure 3 can also be manufactured using a single process. For example, the membrane bridge structure 3 can be first formed on the sacrificial layer 8, and then the first reinforcement member 51 and the second reinforcement member 52 can be formed.

[0078] Furthermore, when the first reinforcement 51 and the second reinforcement 52 are prepared independently from the membrane bridge structure 3, in order to avoid etching the bridge surface 31 of the membrane bridge structure 3 when etching to form the first reinforcement and the second reinforcement, thereby destroying the flatness of the bridge surface 31, causing slit cracks, and weakening the stress bearing capacity of the membrane bridge structure 3, Figure 6 is a cross-sectional view of another MEMS switch of an embodiment of the present disclosure; as shown in Figure 6, in the embodiment of the present disclosure, a protective layer 6 is formed on the side of the bridge surface 31 of the membrane bridge structure 3 facing away from the substrate 1, and the first reinforcement and the second reinforcement are arranged on the side of the protective layer 6 facing away from the substrate 1 (for the specific preparation process steps of this structure, please refer to the following preparation method).

[0079] When the MEMS switch includes a first reinforcement member 51 and a second reinforcement member 52, if the first reinforcement portion 511 of the first reinforcement member 51, located on the bridge deck 31, forms a right angle with the plane of the bridge deck 31, this will result in a relatively concentrated stress at the right angle. Similarly, if the third reinforcement portion 521 of the second reinforcement member, located on the bridge deck 31, forms a right angle with the plane of the bridge deck 31, this will also result in a relatively concentrated stress at the right angle. To alleviate this problem, in some examples, FIG7 is a schematic diagram of the connection position between the bridge deck and the first reinforcement member of the MEMS switch of the present disclosure. As shown in FIG7, the first reinforcement portion 511 has a first side surface S1 disposed opposite the third reinforcement portion 521, and a second side surface opposite the first side surface S1 and connected to the first connecting portion. The third reinforcement portion 521 has a third side surface disposed opposite the first reinforcement portion 511, and a fourth side surface opposite the third side surface and connected to the second connecting portion 523. The first side surface can be a curved surface, and the third side surface can also be a curved surface. In this way, the first side surface S1 of the first reinforcement part 511 will have a smooth transition to the plane of the bridge deck 31, which will alleviate the problem of stress concentration. Similarly, the third side surface of the third reinforcement part 521 will also have a smooth transition to the plane of the bridge deck 31, which can also alleviate the problem of stress concentration. Of course, in other examples, Figure 8 is another schematic diagram of the connection position of the bridge deck and the first reinforcement part of the MEMS switch embodiment of the present disclosure. As shown in Figure 8, the first side surface S1 of the first reinforcement part 511 can also be designed as an inclined surface relative to the plane of the bridge deck 31, so that the dihedral angle formed by the first side surface S1 and the plane of the bridge deck 31 is an obtuse angle. Similarly, the third side surface of the third reinforcement part 521 can be designed as an inclined surface relative to the plane of the bridge deck 31, so that the dihedral angle formed by the third side surface and the plane of the bridge deck 31 is an obtuse angle. In this way, there is a transition process from the first side surface to the plane of the bridge deck 31, and from the third side surface to the plane of the bridge deck 31, thereby alleviating the problem of stress concentration. Furthermore, the dihedral angle formed by the first side surface S1 and the plane where the bridge deck 31 is located, and the dihedral angle formed by the third side surface and the plane where the bridge deck 31 is located can both be approximately 110° to 140°.

[0080] In some examples, regardless of which of the above structures a MEMS switch employs, the base substrate 1 can be a glass substrate. Compared to silicon-based MEMS switches, the production of glass-based MEMS switches can break free from wafer line limitations, enabling the fabrication of large-area MEMS switches, thereby significantly reducing production costs.

[0081] Correspondingly, with respect to the MEMS switch in the above examples, an embodiment of the present disclosure further provides a method for preparing a MEMS switch, which can be used to prepare any of the above MEMS switches.

[0082] Specifically, the preparation method of the MEMS switch includes the following steps:

[0083] S01, providing a substrate 1;

[0084] S02, forming a signal electrode 21, a first reference electrode 22 and a second reference electrode 23 on the base substrate 1; the first reference electrode 22 and the second reference electrode 23 are located on both sides of the extending direction of the signal electrode 21;

[0085] S03, forming an interlayer dielectric layer 4 on the side of the layer where the signal electrode 21, the first reference electrode 22, and the second reference electrode 23 are located away from the base substrate 1, wherein the interlayer dielectric layer 4 at least covers the side of the signal electrode 21 away from the base substrate 1;

[0086] S04, forming a film bridge structure 3 on the side of the interlayer dielectric layer 4 away from the substrate 1; wherein,

[0087] The membrane bridge structure 3 includes a bridge deck 31, a first support portion 32, and a second support portion 33. The bridge deck 31 has a first end and a second end, the first end connected to the first support portion 32, and the second end connected to the second support portion 33. The orthographic projection of the first support portion 32 on the substrate 1 is located above the orthographic projection of the first reference electrode 22 on the substrate 1, and the orthographic projection of the second support portion 33 on the substrate 1 is located above the orthographic projection of the second reference electrode 23 on the substrate 1. A first gap d1 is defined between the bridge deck 31 and the interlayer dielectric layer 4 on the signal electrode 21. The width of the overlapped portion of the first end and the orthographic projection of the first support portion 32 on the substrate 1 in the first direction is a first width W1, and the width of the overlapped portion of the second end and the orthographic projection of the second support portion 33 on the substrate 1 in the first direction is a second width W2. The first direction is the direction from the first reference electrode 22 to the second reference electrode 23. Both the first width W1 and the second width W2 are no less than half of the first gap d1.

[0088] In order to make the preparation method of the MEMS switch of the embodiment of the present disclosure clearer, the following description is made with reference to specific examples.

[0089] Example 1: Figure 9 is a flow chart of Example 1 of a method for fabricating a MEMS switch according to an embodiment of the present disclosure. As shown in Figure 9 , the thickness of the bridge deck 31 of the membrane bridge structure 3 is no less than the first gap d1. For example, the thicknesses of the first support portion 32 and the second support portion 33 are both equal to the thickness of the bridge deck 31, and the thickness of the bridge deck 31 is also equal to the first gap d1. The method for fabricating a MEMS switch in this case may specifically include the following steps:

[0090] S11, providing a base substrate 1.

[0091] In some examples, the base substrate 1 includes but is not limited to a glass substrate. In the embodiment of the present disclosure, only a glass substrate is used as the base substrate 1 for illustration.

[0092] S12 , forming a signal electrode 21 , a first reference electrode 22 and a second reference electrode 23 on the base substrate 1 .

[0093] In some examples, step S12 may specifically include forming a first conductive film by sputtering or electroplating, and patterning the film to form a signal electrode 21 , a first reference electrode 22 , and a second reference electrode 23 .

[0094] For example, when the first conductive film is formed by electroplating, taking copper Cu as the material of the first conductive film as an example, step S12 may specifically include: using a sputtering process to sequentially form MO / Cu or Ti / Cu metal as a first seed layer, and then depositing 1 to 2 μm thick copper by electroplating, and then forming the signal electrode 21, the first reference electrode 22, and the second reference electrode 23 by exposure, development, and etching. There are two electroplating methods. The first is an additive method. After the first seed layer is deposited, a photolithography process is used to form an electroplated PR barrier, and then electroplating is performed. After the electroplating is completed, a strip and copper etching process are performed to form the patterned signal electrode 21, the first reference electrode 22, and the second reference electrode 23. The second is a subtractive method. After the first seed layer is deposited, electroplating is directly performed to form a certain thickness of copper, and then the patterning is achieved by photolithography and etching.

[0095] S13 , forming an interlayer dielectric layer 4 on a side of the layer where the signal electrode 21 , the first reference electrode 22 , and the second reference electrode 23 are located, away from the base substrate 1 , wherein the interlayer dielectric layer 4 at least covers the signal electrode 21 .

[0096] In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide or silicon nitride, and has a thickness of 0.1 to 0.2 μm. Step S13 may specifically include depositing the interlayer dielectric layer 4 using a standard process such as plasma enhanced chemical vapor deposition (PECVD), and patterning the interlayer dielectric layer 4 to form a pattern.

[0097] S14 , forming a sacrificial layer 8 on the side of the interlayer dielectric layer 4 facing away from the base substrate 1 .

[0098] In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, and the thickness of the sacrificial layer 8 is approximately 1.5 μm. Taking the sacrificial layer 8 as an example, using photoresist, step S14 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 facing away from the substrate 1, exposing the interlayer dielectric layer 4 using a corresponding mask, causing the photoresist to be denatured after being irradiated with ultraviolet light, and then developing the layer using an acetone solution as a developer to remove the denatured photoresist, thereby forming a pattern including the sacrificial layer 8.

[0099] S15 , forming a membrane bridge structure 3 on the side of the sacrificial layer 8 facing away from the substrate 1 .

[0100] In some examples, step S15 may specifically include forming a second conductive film by sputtering or electroplating, and patterning the film to form a pattern including the film bridge structure 3 .

[0101] For example, when the second conductive film is formed by electroplating, taking copper Cu as the material of the second conductive film as an example, step S152 may specifically include: using a sputtering process to sequentially form MO / Cu or Ti / Cu metal as the second seed layer, and then depositing copper with a thickness of about 1.5 μm by electroplating, and then forming a membrane bridge structure 3 by exposure, development and etching. There are two electroplating methods. The first is an additive method. After the second seed layer is deposited, a photolithography process is used to form an electroplated PR retaining wall, and then electroplating is performed. After the electroplating is completed, a strip and copper etching process are performed to form a patterned membrane bridge structure 3. The second is a subtractive method. After the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and then its patterning is achieved through photolithography and etching processes.

[0102] S16 , releasing the sacrificial layer 8 .

[0103] In some examples, wet etching may be used to release the sacrificial layer 8 in step S16 , for example, using an isopropyl alcohol solution to release the sacrificial layer 8 .

[0104] This completes the fabrication of the MEMS switch. In this fabrication method, the thickness of the sacrificial layer 8, or the first gap d1 between the bridge deck 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, is approximately 1.5 μm. The width of the connection area between the first end of the bridge deck 31 and the first support portion 32 of the membrane bridge structure 3 formed by this fabrication method is a first width W1, and the width of the connection area between the second end and the second support portion 33 is a second width W2. Both the first width W1 and the second width W2 are approximately 0.8 μm.

[0105] Example 2: FIG10 is a flow chart of Example 2 of a method for fabricating a MEMS switch according to an embodiment of the present disclosure. Referring to FIG10 , compared to Example 1, a first reinforcement member and a second reinforcement member are added. The method for fabricating a MEMS switch of this structure specifically includes the following steps:

[0106] S21, providing a base substrate 1.

[0107] In some examples, the base substrate 1 includes but is not limited to a glass substrate. In the embodiment of the present disclosure, only a glass substrate is used as the base substrate 1 for illustration.

[0108] S22 , forming a signal electrode 21 , a first reference electrode 22 and a second reference electrode 23 on the base substrate 1 .

[0109] In some examples, step S22 may specifically include forming a first conductive film by sputtering or electroplating, and patterning the film to form a signal electrode 21 , a first reference electrode 22 , and a second reference electrode 23 .

[0110] For example, when the first conductive film is formed by electroplating, taking copper Cu as the material of the first conductive film as an example, step S22 may specifically include: forming MO / Cu or Ti / Cu metal as the first seed layer in sequence by sputtering process, and then depositing 1-2 μm thick copper by electroplating, and then forming the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 by exposure, development and etching. There are two electroplating methods. The first is the additive method. After the first seed layer is deposited, the electroplated PR barrier is formed by the photolithography process, and then electroplating is performed. After the electroplating is completed, the strip and copper etching process are performed to form the patterned signal electrode 21, the first reference electrode 22 and the second reference electrode 23. The second is the subtractive method. After the first seed layer is deposited, electroplating is directly performed to form a certain thickness of copper, and then the patterning is achieved by photolithography and etching.

[0111] S23 , forming an interlayer dielectric layer 4 on a side of the layer where the signal electrode 21 , the first reference electrode 22 , and the second reference electrode 23 are located, away from the base substrate 1 , wherein the interlayer dielectric layer 4 at least covers the signal electrode 21 .

[0112] In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide or silicon nitride, and has a thickness of 0.1 to 0.2 μm. Step S23 may specifically include depositing the interlayer dielectric layer 4 using a standard process such as plasma enhanced chemical vapor deposition (PECVD), and patterning the interlayer dielectric layer 4 to form a pattern.

[0113] S24 , forming a sacrificial layer 8 on the side of the interlayer dielectric layer 4 facing away from the base substrate 1 .

[0114] In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, and the thickness of the sacrificial layer 8 is approximately 1.5 μm. Taking the sacrificial layer 8 as an example, using photoresist, step S24 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 facing away from the substrate 1, exposing the interlayer dielectric layer 4 using a corresponding mask, causing the photoresist to be denatured after being irradiated with ultraviolet light, and then developing the denatured photoresist using an acetone solution as a developer to remove the denatured photoresist, thereby forming a pattern including the sacrificial layer 8.

[0115] S25 , forming a membrane bridge structure 3 on the side of the sacrificial layer 8 facing away from the substrate 1 .

[0116] In some examples, step S25 may specifically include forming a second conductive film by sputtering or electroplating, and patterning the film to form a pattern including the film bridge structure 3 .

[0117] For example, when the second conductive film is formed by electroplating, taking copper Cu as the material of the second conductive film as an example, step S25 may specifically include: using a sputtering process to sequentially form MO / Cu or Ti / Cu metal as the second seed layer, and then depositing copper with a thickness of about 1.5 μm by electroplating, and then forming a membrane bridge structure 3 by exposure, development and etching. There are two electroplating methods. The first is an additive method. After the second seed layer is deposited, a photolithography process is used to form an electroplated PR retaining wall, and then electroplating is performed. After the electroplating is completed, a Strip and copper etching process are performed to form a patterned membrane bridge structure 3. The second is a subtractive method. After the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and then its patterning is achieved through photolithography and etching processes.

[0118] S26 , forming a first reinforcing member and a second reinforcing member on the side of the membrane bridge structure 3 facing away from the substrate 1 .

[0119] In some examples, step S26 may specifically include forming a third conductive film by a method including but not limited to sputtering, and then forming a pattern including the first reinforcement and the second reinforcement by photolithography and etching processes.

[0120] S27 , releasing the sacrificial layer 8 .

[0121] In some examples, wet etching may be used to release the sacrificial layer 8 in step S27 , for example, using an isopropyl alcohol solution to release the sacrificial layer 8 .

[0122] This completes the fabrication of the MEMS switch. In this fabrication method, the thickness of the sacrificial layer 8, or the first gap d1 between the bridge deck 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, is approximately 1.5 μm. The width of the connection area between the first end of the bridge deck 31 and the first support portion 32 of the membrane bridge structure 3 formed by this fabrication method is a first width W1, and the width of the connection area between the second end and the second support portion 33 is a second width W2. Both the first width W1 and the second width W2 are approximately 0.8 μm.

[0123] Example 3: FIG11 is a flow chart of Example 3 of a method for fabricating a MEMS switch according to an embodiment of the present disclosure. Referring to FIG11 , compared to Example 2, in this example, the first and second reinforcement members and the membrane bridge structure 3 are formed in a single process. The method for fabricating a MEMS switch of this structure specifically includes the following steps:

[0124] S31, providing a base substrate 1.

[0125] In some examples, the base substrate 1 includes but is not limited to a glass substrate. In the embodiment of the present disclosure, only a glass substrate is used as the base substrate 1 for illustration.

[0126] S32 , forming a signal electrode 21 , a first reference electrode 22 and a second reference electrode 23 on the base substrate 1 .

[0127] In some examples, step S32 may specifically include forming a first conductive film by sputtering or electroplating, and patterning the film to form the signal electrode 21 , the first reference electrode 22 , and the second reference electrode 23 .

[0128] For example, when the first conductive film is formed by electroplating, taking copper Cu as the material of the first conductive film as an example, step S32 may specifically include: using a sputtering process to sequentially form MO / Cu or Ti / Cu metal as a first seed layer, and then depositing 1 to 2 μm thick copper by electroplating, and then forming the signal electrode 21, the first reference electrode 22, and the second reference electrode 23 by exposure, development, and etching. There are two electroplating methods. The first is an additive method. After the first seed layer is deposited, a photolithography process is used to form an electroplated PR barrier, and then electroplating is performed. After the electroplating is completed, a strip and copper etching process are performed to form the patterned signal electrode 21, the first reference electrode 22, and the second reference electrode 23. The second is a subtractive method. After the first seed layer is deposited, electroplating is directly performed to form a certain thickness of copper, and then the patterning is achieved by photolithography and etching.

[0129] S33 , forming an interlayer dielectric layer 4 on the side of the layer where the signal electrode 21 , the first reference electrode 22 , and the second reference electrode 23 are located, away from the base substrate 1 , wherein the interlayer dielectric layer 4 at least covers the signal electrode 21 .

[0130] In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide or silicon nitride, and has a thickness of 0.1 to 0.2 μm. Step S33 may specifically include depositing the interlayer dielectric layer 4 using a standard process such as plasma enhanced chemical vapor deposition (PECVD), and patterning the interlayer dielectric layer 4 to form a pattern.

[0131] S34 , forming a sacrificial layer 8 on the side of the interlayer dielectric layer 4 facing away from the substrate 1 .

[0132] In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, and the thickness of the sacrificial layer 8 is approximately 1.5 μm. Taking the sacrificial layer 8 as an example, using photoresist, step S34 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 facing away from the substrate 1, exposing the interlayer dielectric layer 4 using a corresponding mask, causing the photoresist to be denatured after being irradiated with ultraviolet light, and then developing the layer using an acetone solution as a developer to remove the denatured photoresist, thereby forming a pattern including the sacrificial layer 8.

[0133] S35 , forming a membrane bridge structure 3 , a first reinforcing member, and a second reinforcing member on the side of the sacrificial layer 8 facing away from the base substrate 1 .

[0134] In some examples, step S35 may specifically include forming a second conductive film by sputtering or electroplating, and patterning the film to form a pattern including the membrane bridge structure 3 , the first reinforcement, and the second reinforcement.

[0135] For example: when the second conductive film is formed by electroplating, taking copper Cu as the material of the second conductive film as an example, step S35 may specifically include: using a sputtering process to sequentially form MO / Cu or Ti / Cu metal as the second seed layer, and then depositing copper with a thickness of about 1.8 to 2.0 μm by electroplating, and then forming the semi-finished product of the membrane bridge structure 3, the first reinforcement and the second reinforcement by exposure, development and etching, and finally etching the position of the semi-finished product of the membrane bridge structure 3 corresponding to the bridge deck 31 to form the bridge deck 31 of the membrane bridge. Among them, there are two electroplating methods. The first is the additive method. After the second seed layer is deposited, the electroplated PR retaining wall is first formed by a photolithography process, and then electroplating is performed. After the electroplating is completed, the Strip and copper etching processes are performed to form the patterned membrane bridge structure 3. The second is the subtractive method. After the first seed layer is deposited, electroplating is directly performed to form a certain thickness of copper, and then its patterning is achieved by photolithography and etching processes.

[0136] S36 , releasing the sacrificial layer 8 .

[0137] In some examples, wet etching may be used to release the sacrificial layer 8 in step S36 , for example, using an isopropyl alcohol solution to release the sacrificial layer 8 .

[0138] This completes the fabrication of the MEMS switch. In this fabrication method, the thickness of the sacrificial layer 8, or the first gap d1 between the bridge deck 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, is approximately 1.5 μm. The width of the connection area between the first end of the bridge deck 31 and the first support portion 32 of the membrane bridge structure 3 formed by this fabrication method is a first width W1, and the width of the connection area between the second end and the second support portion 33 is a second width W2. Both the first width W1 and the second width W2 are approximately 1 μm.

[0139] Example 4. FIG12 is a flow chart of Example 4 of a method for fabricating a MEMS switch according to an embodiment of the present disclosure. Referring to FIG12 , compared to Example 2, a protective layer 6 is added between the membrane bridge and the first and second reinforcing members. The method for fabricating a MEMS switch of this structure specifically includes the following steps:

[0140] S41, providing a base substrate 1.

[0141] In some examples, the base substrate 1 includes but is not limited to a glass substrate. In the embodiment of the present disclosure, only a glass substrate is used as the base substrate 1 for illustration.

[0142] S42 , forming the signal electrode 21 , the first reference electrode 22 and the second reference electrode 23 on the base substrate 1 .

[0143] In some examples, step S42 may specifically include forming a first conductive film by sputtering or electroplating, and patterning the film to form the signal electrode 21 , the first reference electrode 22 , and the second reference electrode 23 .

[0144] For example, when the first conductive film is formed by electroplating, taking copper Cu as the material of the first conductive film as an example, step S42 may specifically include: using a sputtering process to sequentially form MO / Cu or Ti / Cu metal as a first seed layer, and then depositing 1-2 μm thick copper by electroplating, and then forming the signal electrode 21, the first reference electrode 22, and the second reference electrode 23 by exposure, development, and etching. There are two electroplating methods. The first is an additive method. After the first seed layer is deposited, a photolithography process is used to form an electroplated PR barrier, and then electroplating is performed. After the electroplating is completed, a strip and copper etching process are performed to form the patterned signal electrode 21, the first reference electrode 22, and the second reference electrode 23. The second is a subtractive method. After the first seed layer is deposited, electroplating is directly performed to form a certain thickness of copper, and then the patterning is achieved by photolithography and etching.

[0145] S43 , forming an interlayer dielectric layer 4 on the side of the layer where the signal electrode 21 , the first reference electrode 22 , and the second reference electrode 23 are located, away from the base substrate 1 , wherein the interlayer dielectric layer 4 at least covers the signal electrode 21 .

[0146] In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide or silicon nitride, and has a thickness of 0.1 to 0.2 μm. Step S43 may specifically include depositing the interlayer dielectric layer 4 using a standard process such as plasma enhanced chemical vapor deposition (PECVD), and patterning the interlayer dielectric layer 4 to form a pattern.

[0147] S44 , forming a sacrificial layer 8 on the side of the interlayer dielectric layer 4 facing away from the base substrate 1 .

[0148] In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, and the thickness of the sacrificial layer 8 is approximately 1.5 μm. Taking the sacrificial layer 8 as an example, using photoresist, step S44 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 facing away from the substrate 1, exposing the interlayer dielectric layer 4 using a corresponding mask, causing the photoresist to be denatured after being irradiated with ultraviolet light, and then developing the layer using an acetone solution as a developer to remove the denatured photoresist, thereby forming a pattern including the sacrificial layer 8.

[0149] S45 , forming a membrane bridge structure 3 on the side of the sacrificial layer 8 facing away from the base substrate 1 .

[0150] In some examples, step S45 may specifically include forming a second conductive film by sputtering or electroplating, and patterning the film to form a pattern including the membrane bridge structure 3 .

[0151] For example, when the second conductive film is formed by electroplating, taking copper Cu as the material of the second conductive film as an example, step S45 may specifically include: using a sputtering process to sequentially form MO / Cu or Ti / Cu metal as the second seed layer, and then depositing copper with a thickness of about 1.5 μm by electroplating, and then forming a membrane bridge structure 3 by exposure, development and etching. There are two electroplating methods. The first is an additive method. After the second seed layer is deposited, a photolithography process is used to form an electroplated PR retaining wall, and then electroplating is performed. After the electroplating is completed, a strip and copper etching process are performed to form a patterned membrane bridge structure 3. The second is a subtractive method. After the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and then its patterning is achieved through photolithography and etching processes.

[0152] S46 , forming a protective layer 6 on the side of the membrane bridge structure 3 facing away from the substrate 1 .

[0153] In some examples, the material of the protective layer 6 may be an inorganic material. Step S46 may specifically include forming a thin film of the protective layer 6 by deposition, and then forming a pattern including the protective layer 6 by an etching process.

[0154] S47 , forming a first reinforcing member and a second reinforcing member on a side of the protective layer 6 facing away from the base substrate 1 .

[0155] In some examples, step S46 may specifically include forming a third conductive film by a method including but not limited to sputtering, and then forming a pattern including the first reinforcement and the second reinforcement by photolithography and etching processes.

[0156] S48 , releasing the sacrificial layer 8 .

[0157] In some examples, wet etching may be used to release the sacrificial layer 8 in step S48 , for example, using an isopropyl alcohol solution to release the sacrificial layer 8 .

[0158] This completes the fabrication of the MEMS switch. In this fabrication method, the thickness of the sacrificial layer 8, or the first gap d1 between the bridge deck 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, is approximately 1.5 μm. The width of the connection area between the first end of the bridge deck 31 and the first support portion 32 of the membrane bridge structure 3 formed by this fabrication method is a first width W1, and the width of the connection area between the second end and the second support portion 33 is a second width W2. Both the first width W1 and the second width W2 are approximately 0.8 μm.

[0159] Second Example: Figure 13 is a cross-sectional view of another MEMS switch according to the disclosed embodiment. As shown in Figure 13 , the membrane bridge structure 3 of this MEMS switch is a single-arm bridge. This MEMS switch is substantially identical to the first example, differing only in that it includes only a single support portion 30. This MEMS switch also includes a contact assembly 7 on the side of the second reference electrode 23 facing away from the substrate 1. When the bridge surface 31 is pulled downward, the contact assembly 7 connects to the second reference electrode 23, thereby opening the switch. The remaining structure is the same as that of the first example and will not be further described.

[0160] In addition, for this type of MEMS switch, when a reinforcement member is provided, the structure of the reinforcement member may be the same as that of the first reinforcement member 51 in the first example, and therefore will not be described in detail.

[0161] Correspondingly, the preparation method of the MEMS switch of this structure may also adopt the preparation method in the first example, so it will not be described in detail here.

[0162] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A micromechanical switch, comprising: substrate substrate; A signal electrode, a first reference electrode and a second reference electrode are arranged on the base substrate, and the first reference electrode and the second reference electrode are respectively located on both sides of the extension direction of the signal electrode; an interlayer dielectric layer, covering at least a side of the signal electrode facing away from the substrate; A membrane bridge structure is arranged on a side of the interlayer dielectric layer away from the substrate; wherein the membrane bridge structure includes a bridge deck and at least one supporting portion, the supporting portion being connected to an end of the bridge deck; a first gap is provided between the bridge deck and the interlayer dielectric layer on the signal electrode; the width of the connection position between the supporting portion and the end of the bridge deck on the substrate is a first width in a first direction, the first direction being the direction from the first reference electrode to the second reference electrode; the first width is not less than half of the first gap.

2. The micromechanical switch according to claim 1, wherein: The thickness of the bridge deck of the membrane bridge structure is not less than the first gap.

3. The micromechanical switch according to claim 1, wherein: The thickness of the support portion and the thickness of the bridge deck are both equal to the first gap.

4. The micromechanical switch according to claim 1, wherein: It also includes a reinforcement member, which is arranged on a side of the membrane bridge structure away from the substrate and is located at a connection position between the support portion and the bridge deck; The orthographic projection of the reinforcement member on the base substrate at least covers the orthographic projection of the connection position between the support portion and the bridge deck on the base substrate.

5. The micromechanical switch according to claim 4, wherein: The at least one supporting portion includes a first supporting portion and / or a second supporting portion; the end of the bridge deck includes a first end and a second end; When the support portion includes a first support portion, the first support portion is connected to the first end portion of the bridge deck, the first support portion is located on the side of the first reference electrode away from the substrate, and at least partially overlaps with the orthographic projection of the first reference electrode on the substrate; the reinforcement member includes a first reinforcement member, the first reinforcement member is located between the first support portion and the first end portion The first reinforcement member comprises a first reinforcement portion, a second reinforcement portion, and a first connection portion connecting the first reinforcement portion and the second reinforcement portion; the first reinforcement portion is located on a side of the first end portion away from the substrate substrate, and the second reinforcement portion is located on a side of the first support portion away from the substrate substrate; the orthographic projection of one end of the first reinforcement portion away from the first connection portion on the substrate substrate is located between the orthographic projections of the first reference electrode and the signal electrode on the substrate substrate; When the supporting portion includes a second supporting portion, the second supporting portion is connected to the second end portion of the bridge deck, the second supporting portion is located on the side of the second reference electrode away from the substrate substrate, and at least partially overlaps with the orthographic projection of the second reference electrode on the substrate substrate; the reinforcing member includes a second reinforcing member, and the second reinforcing member is located at the connecting position between the second supporting portion and the second end portion; the second reinforcing member includes a third reinforcing portion, a fourth reinforcing portion, and a second connecting portion connecting the third reinforcing portion and the fourth reinforcing portion; the third reinforcing portion is located on the side of the second end portion away from the substrate substrate, and the fourth reinforcing portion is located on the side of the second supporting portion away from the substrate substrate; the orthographic projection of one end of the third reinforcing portion away from the second connecting portion on the substrate substrate is located between the orthographic projections of the second reference electrode and the signal electrode on the substrate substrate.

6. The micromechanical switch according to claim 5, wherein: When the micromechanical switch includes a first reinforcement member, the first reinforcement member has a first side surface and a second side surface that are arranged opposite to each other, and the second side surface is connected to the first connection portion; the first side surface is a concave arc surface, or the dihedral angle formed by the first side surface and the plane where the bridge surface is located is an obtuse angle; When the micromechanical switch includes a second reinforcement member, the third reinforcement portion has a third side surface and a fourth side surface that are relatively arranged, the fourth side surface is connected to the second connecting portion, the third side surface is a concave arc surface, or the dihedral angle formed by the third side surface and the plane where the bridge deck is located is an obtuse angle.

7. The micromechanical switch according to claim 4, wherein: The membrane bridge structure is made of the same material as that of the reinforcement.

8. The micromechanical switch according to claim 7, wherein: The membrane bridge structure and the reinforcement member are an integrally formed structure.

9. The micromechanical switch according to claim 4, wherein: A protective layer is provided between the bridge deck and the reinforcement member.

10. The micromechanical switch according to claim 1, wherein: The base substrate is a glass substrate.

11. A method for preparing a micromechanical switch, comprising: Providing a substrate; forming a signal electrode, a first reference electrode and a second reference electrode on the base substrate; The first reference electrode and the second reference electrode are located on both sides of the extending direction of the signal electrode; An interlayer dielectric layer is formed on a side of the layer where the signal electrode, the first reference electrode and the second reference electrode are located away from the substrate, wherein the interlayer dielectric layer at least covers a side of the signal electrode away from the substrate; A film bridge structure is formed on the side of the interlayer dielectric layer away from the substrate; wherein, The membrane bridge structure includes a bridge deck and at least one supporting portion, wherein the supporting portion is connected to an end portion of the bridge deck; a first gap is provided between the bridge deck and the interlayer dielectric layer on the signal electrode; a connection position between the supporting portion and the end portion of the bridge deck is projected onto the substrate, and a width in a first direction is a first width, wherein the first direction is a direction in which the first reference electrode points to the second reference electrode; and the first width is not less than half of the first gap.

12. The method for preparing a micromechanical switch according to claim 11, wherein: The thickness of the bridge deck of the membrane bridge structure is not less than the first gap.

13. The method for preparing a micromechanical switch according to claim 11, wherein: The thickness of the supporting parts is equal to the thickness of the bridge deck structure, and the thickness of the bridge deck structure is equal to the first gap.

14. The method for preparing a micromechanical switch according to any one of claims 11 to 13, wherein: The step of forming a film bridge structure on a side of the interlayer dielectric layer away from the substrate includes: A sacrificial layer is formed on a side of the interlayer dielectric layer away from the substrate. The orthographic projection on the base substrate covers the orthographic projection of the signal electrode on the base substrate, the gap between the signal electrode and the first reference electrode, and the gap between the signal electrode and the second reference electrode; A first conductive film is formed on the side of the sacrificial layer away from the substrate as a first seed layer, the first seed layer is electroplated to form a first conductive layer, the first conductive layer is patterned to form a pattern including a membrane bridge structure, and the sacrificial layer is released.

15. The method for preparing a micromechanical switch according to claim 14, wherein: The sacrificial layer is made of photoresist or polyimide.

16. The method for preparing a micromechanical switch according to any one of claims 11 to 13, wherein: Also includes: forming a reinforcing member on a side of the membrane bridge structure facing away from the substrate; The reinforcement member is located at the connection position between the support portion and the bridge deck; The orthographic projection of the reinforcement member on the base substrate at least covers the orthographic projection of the connection position between the support portion and the bridge deck on the base substrate.

17. The method for preparing a micromechanical switch according to claim 16, wherein: The at least one supporting portion includes a first supporting portion and / or a second supporting portion; the end of the bridge deck includes a first end and a second end; When the support portion includes a first support portion, the first support portion is connected to the first end portion of the bridge deck, the first support portion is located on the side of the first reference electrode away from the substrate substrate, and at least partially overlaps with the orthographic projection of the first reference electrode on the substrate substrate; the reinforcement member includes a first reinforcement member, the first reinforcement member is located at the connection position between the first support portion and the first end portion; the first reinforcement member includes a first reinforcement portion, a second reinforcement portion, and a first connection portion connecting the first reinforcement portion and the second reinforcement portion; the first reinforcement portion is located on the side of the first end portion away from the substrate substrate, and the second reinforcement portion is located on the side of the first support portion away from the substrate substrate; the orthographic projection of one end of the first reinforcement portion away from the first connection portion on the substrate substrate is located between the orthographic projections of the first reference electrode and the signal electrode on the substrate substrate; When the support portion includes a second support portion, the second support portion is connected to the second end of the bridge deck. The second supporting portion is connected with the substrate substrate, the second supporting portion is located on the side of the second reference electrode away from the substrate substrate, and at least partially overlaps with the orthographic projection of the second reference electrode on the substrate substrate; the reinforcing member includes a second reinforcing member, and the second reinforcing member is located at the connecting position of the second supporting portion and the second end portion; the second reinforcing member includes a third reinforcing portion, a fourth reinforcing portion, and a second connecting portion connecting the third reinforcing portion and the fourth reinforcing portion; the third reinforcing portion is located on the side of the second end portion away from the substrate substrate, and the fourth reinforcing portion is located on the side of the second supporting portion away from the substrate substrate; the orthographic projection of one end of the third reinforcing portion away from the second connecting portion on the substrate substrate is located between the orthographic projections of the second reference electrode and the signal electrode on the substrate substrate.

18. The method for preparing a micromechanical switch according to claim 17, wherein: When the micromechanical switch includes a first reinforcement member, the first reinforcement member has a first side surface and a second side surface that are arranged opposite to each other, and the second side surface is connected to the first connection portion; the first side surface is a concave arc surface, or the dihedral angle formed by the first side surface and the plane where the bridge surface is located is an obtuse angle; When the micromechanical switch includes a second reinforcement member, the third reinforcement portion has a third side surface and a fourth side surface that are relatively arranged, the fourth side surface is connected to the second connecting portion, the third side surface is a concave arc surface, or the dihedral angle formed by the third side surface and the plane where the bridge deck is located is an obtuse angle.

19. The method for preparing a micromechanical switch according to claim 16, wherein: The reinforcement member and the membrane bridge structure are prepared in a single patterning process.

20. The method for preparing a micromechanical switch according to claim 16, wherein: The method further comprises: Before forming the reinforcing member, a protective layer is formed on a side of the bridge surface of the membrane bridge structure facing away from the substrate.

21. The method for preparing a micromechanical switch according to claim 11, wherein: The base substrate is a glass substrate.

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