CN120113099A - Micromechanical switch and method for manufacturing the same - Google Patents
Micromechanical switch and method for manufacturing the same Download PDFInfo
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- CN120113099A CN120113099A CN202380010702.5A CN202380010702A CN120113099A CN 120113099 A CN120113099 A CN 120113099A CN 202380010702 A CN202380010702 A CN 202380010702A CN 120113099 A CN120113099 A CN 120113099A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H59/00—Electrostatic relays; Electro-adhesion relays
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Abstract
一种微机械开关及其制备方法，属于通信技术领域。该微机械开关包括：衬底基板(1)；信号电极(21)、第一参考电极(22)和第二参考电极(23)，设置在衬底基板(1)上，且第一参考电极(22)和第二参考电极(23)分别位于信号电极(21)延伸方向的两侧；层间介质层(4)，至少覆盖信号电极(21)背离衬底基板(1)的一侧；膜桥结构(3)，设置在层间介质层(4)背离衬底基板(1)的一侧；其中，膜桥结构(3)包括桥面(31)和至少一个支撑部(32，33)，支撑部(32，33)与桥面(31)的端部连接；桥面(31)与信号电极(21)上的层间介质层(4)之间具有第一间隙(d1)；支撑部(32，33)与桥面(31)的端部的连接位置在衬底基板(1)上的正投影，在第一方向上的宽度为第一宽度(W1)，第一方向为第一参考电极(22)指向第二参考电极(23)的方向；第一宽度(W1)不小于第一间隙(d1)的一半。
A micromechanical switch and a preparation method thereof, belonging to the field of communication technology. The micromechanical switch comprises: a substrate (1); a signal electrode (21), a first reference electrode (22) and a second reference electrode (23), which are arranged on the substrate (1), and the first reference electrode (22) and the second reference electrode (23) are respectively located on both sides of the extension direction of the signal electrode (21); an interlayer dielectric layer (4), which at least covers the side of the signal electrode (21) away from the substrate (1); a membrane bridge structure (3), which is arranged on the side of the interlayer dielectric layer (4) away from the substrate (1); wherein the membrane bridge structure (3) comprises a bridge surface (31) and At least one supporting portion (32, 33), the supporting portion (32, 33) being connected to the end of the bridge deck (31); a first gap (d1) being provided between the bridge deck (31) and the interlayer dielectric layer (4) on the signal electrode (21); the width of the connection position of the supporting portion (32, 33) and the end of the bridge deck (31) on the substrate (1) being a first width (W1) in a first direction, the first direction being the direction from the first reference electrode (22) to the second reference electrode (23); and the first width (W1) being not less than half of the first gap (d1).
Description
The disclosure belongs to the technical field of communication, and in particular relates to a micromechanical switch and a preparation method thereof.
RF MEMS (Radio Frequency Micro mechanical switch) is a new technology combining MEMS (Micro-Electro-MECHANICAL SYSTEM; micro-mechanical) with RF (Radio Frequency) technology. The MEMS device has the advantages of small volume, easy integration, low power consumption, high reliability and the like, and can replace a semiconductor device in the traditional wireless communication system. The RF MEMS can be applied to circuits in a device mode, such as MEMS switches, MEMS capacitors and MEMS resonators, and can integrate single devices into the same chip component and application system, such as filters, voltage-controlled oscillators, phase shifters, phased array radar antennas and the like, so that the size of the traditional devices is greatly reduced, the power consumption is reduced, and the performance of the system is improved. RF MEMS switches are one of the important devices in RF MEMS, whose performance has an increasing profound impact on microelectromechanical systems.
Disclosure of Invention
The invention aims to at least solve one of the technical problems in the prior art and provides a micromechanical switch and a preparation method thereof.
Embodiments of the present disclosure provide a micromechanical switch, comprising:
a substrate base;
the signal electrode, the first reference electrode and the second reference electrode are arranged on the substrate base plate, and the first reference electrode and the second reference electrode are respectively positioned at two sides of the extending direction of the signal electrode;
An interlayer dielectric layer at least covering one side of the signal electrode away from the substrate base plate;
The membrane bridge structure is arranged on one side of the interlayer dielectric layer, which is away from the substrate base plate, wherein,
The membrane bridge structure comprises a bridge deck and at least one supporting portion, wherein the supporting portion is connected with the end portion of the bridge deck, a first gap is formed between the bridge deck and the interlayer dielectric layer on the signal electrode, the connecting position of the supporting portion and the end portion of the bridge deck is in orthographic projection on the substrate, the width of the supporting portion and the end portion of the bridge deck in the first direction is a first width, the first direction is the direction that the first reference electrode points to the second reference electrode, and the first width is not smaller than half of the first gap.
Wherein the thickness of the bridge deck of the membrane bridge structure is not less than the first gap.
Wherein, the thickness of supporting part with the thickness of bridge floor all equals with first clearance.
The reinforcement is arranged on one side of the membrane bridge structure, which is away from the substrate base plate, and is positioned at the connection position of the supporting part and the bridge deck; the bridge deck and the supporting portion are overlapped with the orthographic projection part of the reinforcement on the substrate.
The bridge deck comprises at least one support part, at least one bridge deck and at least one support part, wherein the at least one support part comprises a first support part and/or a second support part;
When the support part comprises a first support part, the first support part is connected with a first end part of the bridge deck, the first support part is positioned on one side of the first reference electrode, which is away from the substrate, and at least partially overlapped with the orthographic projection of the first reference electrode on the substrate, the reinforcement comprises a first reinforcement, the first reinforcement is positioned at a connection position of the first support part and the first end part, the first reinforcement comprises a first reinforcement part, a second reinforcement part and a first connection part connected between the first reinforcement part and the second reinforcement part, the first reinforcement part is positioned on one side of the first end part, which is away from the substrate, the second reinforcement part is positioned on one side of the first support part, which is away from the substrate, the orthographic projection of one end of the first reinforcement part, which is away from the first connection part, on the substrate, is positioned between the orthographic projection of the first reference electrode and the signal electrode on the substrate;
when the support part comprises a second support part, the second support part is connected with the second end part of the bridge deck, the second support part is positioned on one side of the second reference electrode, which is away from the substrate, and at least partially overlapped with the orthographic projection of the second reference electrode on the substrate, the reinforcement comprises a second reinforcement, the second reinforcement is positioned at the connection position of the second support part and the second end part, the second reinforcement comprises a third reinforcement part, a fourth reinforcement part and a second connection part, which is connected between the third reinforcement part and the fourth reinforcement part, the third reinforcement part is positioned on one side of the second end part, which is away from the substrate, the fourth reinforcement part is positioned on one side of the second support part, which is away from the substrate, and the orthographic projection of one end of the third reinforcement part, which is away from the second connection part, on the substrate, is positioned between the second reference electrode and the orthographic projection of the signal electrode on the substrate.
When the micromechanical switch comprises a first reinforcement, the first reinforcement part is provided with a first side surface which is opposite to the first connection part, the first side surface is a concave cambered surface, or a dihedral angle formed by the first side surface and a plane where the bridge deck is located is an obtuse angle;
When the micromechanical switch comprises a second reinforcement, the third reinforcement part is provided with a third side surface which is opposite to the second connection part, and the third side surface is a concave cambered surface or a dihedral angle formed by the third side surface and a plane where the bridge deck is located is an obtuse angle.
Wherein the membrane bridge structure is the same material as the stiffener.
Wherein, the membrane bridge structure and the reinforcement are an integrated structure.
Wherein a protective layer is provided between the deck and the reinforcement.
Wherein the substrate is a glass substrate.
The embodiment of the disclosure provides a preparation method of a micromechanical switch, which comprises the following steps:
providing a substrate base plate;
forming a signal electrode, a first reference electrode and a second reference electrode on the substrate, wherein the first reference electrode and the second reference electrode are positioned at two sides of the extending direction of the signal electrode;
forming an interlayer dielectric layer on one side of the layers of the signal electrode, the first reference electrode and the second reference electrode, which is away from the substrate, wherein the interlayer dielectric layer at least covers one side of the signal electrode, which is away from the substrate;
a film bridge structure is formed on one side of the interlayer dielectric layer away from the substrate base plate, wherein,
The membrane bridge structure comprises a bridge deck and at least one supporting portion, wherein the supporting portion is connected with the end portion of the bridge deck, a first gap is formed between the bridge deck and the interlayer dielectric layer on the signal electrode, the connecting position of the supporting portion and the end portion of the bridge deck is in orthographic projection on the substrate, the width of the supporting portion and the end portion of the bridge deck in the first direction is a first width, the first direction is the direction that the first reference electrode points to the second reference electrode, and the first width is not smaller than the first gap.
Wherein the thickness of the bridge deck of the membrane bridge structure is not less than the first gap.
The thickness of the supporting portion is equal to that of the bridge deck structure, and the thickness of the bridge deck structure is equal to the first gap.
The step of forming a film bridge structure on one side of the interlayer dielectric layer away from the substrate base plate comprises the following steps:
Forming a sacrificial layer on one side of the interlayer dielectric layer, which is away from the substrate, wherein orthographic projection of the sacrificial layer on the substrate covers orthographic projection of the signal electrode on the substrate, a gap between the signal electrode and a first reference electrode and a gap between the signal electrode and a second reference electrode;
And forming a first conductive film on one side of the sacrificial layer, which is away from the substrate, as a first seed layer, electroplating the first seed layer to form a first conductive layer, patterning the first conductive layer to form a pattern comprising a film bridge structure, and releasing the sacrificial layer.
Wherein, the material of the sacrificial layer adopts photoresist or polyimide.
Wherein, the preparation method also comprises the following steps:
The method comprises the steps of forming a reinforcement on one side of the film bridge structure, which is far away from a substrate, wherein the reinforcement is positioned at the connection position of a supporting part and a bridge deck, and the orthographic projection of the reinforcement on the substrate at least covers the orthographic projection of the connection position of the supporting part and the bridge deck on the substrate.
The bridge deck comprises at least one support part, at least one bridge deck and at least one support part, wherein the at least one support part comprises a first support part and/or a second support part;
When the support part comprises a first support part, the first support part is connected with a first end part of the bridge deck, the first support part is positioned on one side of the first reference electrode, which is away from the substrate, and at least partially overlapped with the orthographic projection of the first reference electrode on the substrate, the reinforcement comprises a first reinforcement, the first reinforcement is positioned at a connection position of the first support part and the first end part, the first reinforcement comprises a first reinforcement part, a second reinforcement part and a first connection part connected between the first reinforcement part and the second reinforcement part, the first reinforcement part is positioned on one side of the first end part, which is away from the substrate, the second reinforcement part is positioned on one side of the first support part, which is away from the substrate, the orthographic projection of one end of the first reinforcement part, which is away from the first connection part, on the substrate, is positioned between the orthographic projection of the first reference electrode and the signal electrode on the substrate;
when the support part comprises a second support part, the second support part is connected with the second end part of the bridge deck, the second support part is positioned on one side of the second reference electrode, which is away from the substrate, and at least partially overlapped with the orthographic projection of the second reference electrode on the substrate, the reinforcement comprises a second reinforcement, the second reinforcement is positioned at the connection position of the second support part and the second end part, the second reinforcement comprises a third reinforcement part, a fourth reinforcement part and a second connection part, which is connected between the third reinforcement part and the fourth reinforcement part, the third reinforcement part is positioned on one side of the second end part, which is away from the substrate, the fourth reinforcement part is positioned on one side of the second support part, which is away from the substrate, and the orthographic projection of one end of the third reinforcement part, which is away from the second connection part, on the substrate, is positioned between the second reference electrode and the orthographic projection of the signal electrode on the substrate.
When the micromechanical switch comprises a first reinforcement, the first reinforcement part is provided with a first side surface which is opposite to the first connection part, the first side surface is a concave cambered surface, or a dihedral angle formed by the first side surface and a plane where the bridge deck is located is an obtuse angle;
When the micromechanical switch comprises a second reinforcement, the third reinforcement part is provided with a third side surface which is opposite to the second connection part, and the third side surface is a concave cambered surface or a dihedral angle formed by the third side surface and a plane where the bridge deck is located is an obtuse angle.
Wherein the reinforcement and the membrane bridge structure are prepared by adopting a one-time composition process.
Wherein, the preparation method also comprises the following steps:
And before the reinforcement is formed, forming a protective layer on one side of the bridge deck of the film bridge structure, which faces away from the substrate.
Wherein the substrate is a glass substrate.
Fig.1 is a cross-sectional view of an exemplary micro-mechanical (MEMS) switch.
FIG.2 is a schematic illustration of deck collapse of the MEMS switch of FIG. 1.
Fig.3 is a cross-sectional view of a MEMS switch according to an embodiment of the present disclosure.
Fig.4 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure.
Fig.5 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure.
Fig.6 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure.
Fig. 7 is a schematic diagram of connection positions of a bridge deck and a first stiffener of a MEMS switch according to an embodiment of the present disclosure.
Fig. 8 is another schematic diagram of connection locations of a bridge deck and a first stiffener of a MEMS switch according to an embodiment of the present disclosure.
Fig. 9 is a flowchart of an example one of a method of manufacturing a MEMS switch according to an embodiment of the disclosure.
Fig. 10 is a flowchart of an example two of a method of manufacturing a MEMS switch according to an embodiment of the disclosure.
Fig. 11 is a flowchart of an example three of a method of manufacturing a MEMS switch according to an embodiment of the disclosure.
Fig.12 is a flowchart of an example four of a method of manufacturing a MEMS switch according to an embodiment of the disclosure.
Fig.13 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure.
The present invention will be described in further detail below with reference to the drawings and detailed description for the purpose of better understanding of the technical solution of the present invention to those skilled in the art.
Unless defined otherwise, technical or scientific terms used in this disclosure should be given the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first," "second," and the like, as used in this disclosure, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Likewise, the terms "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
Fig.1 is a cross-sectional view of an exemplary micro-mechanical (MEMS) switch, which, as shown in fig.1, includes a substrate base 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 at two sides of the extending direction of the signal electrode 21, and the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 form a coplanar waveguide (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 other electrodes. The membrane bridge structure 3 is arranged on one side of the interlayer dielectric layer 4, which is away from the substrate 1, and the first support part 32 and the second support part 33 of the membrane bridge structure 3 are respectively positioned on the first reference electrode 22 and the second reference electrode 23, and a first gap d1 is formed between the bridge deck 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4 on the signal electrode 21.
In this structure, the interlayer dielectric layer 4 covers only the signal electrode 21 and does not cover the first reference electrode 22 and the second reference electrode 23, and the first support portion 32 and the second support portion 33 of the film bridge structure 3 are provided on the first reference electrode 22 and the second reference electrode 23, respectively, so that when a dc bias voltage is applied to the first reference electrode 22 and the second reference electrode 23, the film bridge structure 3 is loaded with the same dc bias voltage as the first reference electrode 22 and the second reference electrode 23. The first reference electrode 22 and the second reference electrode 23 may be supplied with ground potential for control purposes, i.e. the potentials of the first reference electrode 22 and the second reference electrode 23 are referenced to ground. Of course, the interlayer dielectric layer 4 may cover the first reference electrode 22 and the second reference electrode 23 simultaneously with the signal electrode 21, and in this case, it is necessary to lay out the signal lines for the film bridge structure 3 to apply voltages thereto. In the embodiment of the present disclosure, for convenience of control and miniaturization of the device, it is preferable that the interlayer dielectric layer 4 covers only the signal electrode 21, and the film bridge structure 3 is loaded with the same dc bias voltage as the first reference electrode 22 and the second reference electrode 23.
The working principle of the MEMS switch is that when the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 are respectively loaded with corresponding dc bias voltages, the electric potentials of the membrane bridge structure 3 and the first reference electrode 22 and the second reference electrode 23 are equal, at this time, the bridge deck 31 of the membrane bridge structure 3 will be bent and pulled down by the electrostatic force generated between the membrane bridge structure 3 and the signal electrode 21, and finally contact with the interlayer dielectric layer 4 on the signal electrode 21, because the distance between the bridge deck 31 of the membrane bridge structure 3 and the signal electrode 21 in the initial state is large (i.e. the first gap d 1), the capacitance is small, the radio frequency signal will be transmitted along the signal electrode 21, and as the bridge deck 31 structure approaches the signal electrode 21, the capacitance increases, the radio frequency signal will be coupled to the membrane bridge structure 3, so as to realize the closing of the MEMS switch. In contrast, when the dc bias voltages applied to the number electrode, the first reference electrode 22 and the second reference electrode 23 are removed, the bridge deck 31 returns to the original position due to the elastic restoring force of the bridge deck 31 itself of the membrane bridge structure 3, the distance between the bridge deck 31 and the signal electrode 21 becomes larger, the capacitance is reduced, the radio frequency signal will not be coupled to the membrane bridge structure 3 any more, and will continue to be transmitted along the signal electrode 21, thereby realizing the disconnection of the MEMS switch.
For the preparation of a membrane bridge in a MEMS switch, typically, a sacrificial layer 8 is formed on a substrate 1 formed with a signal electrode 21, a first reference electrode 22, a second reference electrode 23, and an interlayer dielectric layer 4, a conductive film is formed on the sacrificial layer 8 facing away from the substrate 1, a membrane bridge structure 3 is formed, and finally the sacrificial layer 8 is released. Fig. 2 is a schematic view illustrating collapse of the bridge deck 31 of the MEMS switch shown in fig. 1, and as shown in fig. 2, the inventor has found that, since the conductive film forming the membrane bridge structure 3 is thin, the first support portion 32 and the second support portion 33 are relatively thin, and in the process of releasing the sacrificial layer 8, the bridge deck 31 of the membrane bridge structure 3 easily causes collapse of the membrane bridge due to self gravity and electrostatic force, and the yield is extremely low.
Aiming at the problems, the embodiment of the disclosure provides the following technical scheme.
Before describing the MEMS switch of the embodiments of the present disclosure, it should be noted that the MEMS switch of the embodiments of the present disclosure may be a two-arm bridge or a single-arm bridge as the membrane bridge structure 3. For convenience of description, two support portions in the double-arm bridge will be referred to as a first support portion 32 and a second support portion 33, and the first support portion 32 corresponds to the first reference electrode 22 position, and the second support portion 33 corresponds to the second reference electrode 23 position. In addition, the single-armed bridge differs largely from the double-armed bridge only in that the single-armed bridge has only one support, which in the disclosed embodiment corresponds to the first reference electrode 22 position, it being understood that this support may also correspond to the second reference electrode position. For convenience of description in the following examples, the MEMS switch of the embodiments of the present disclosure will be described with the membrane bridge structure 3 as a double-arm bridge and a single-arm bridge, respectively.
A first example is that fig. 3 is a cross-sectional view of a MEMS switch according to an embodiment of the disclosure, and that the membrane bridge structure 3 of the micromechanical switch is a double-arm bridge as shown in fig. 3, and 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 at two sides of the extending direction of the signal electrode 21, and 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 other electrodes. The membrane bridge structure 3 is arranged on the side of the interlayer dielectric layer 4 facing away from the substrate 1.
The film bridge structure 3 comprises a bridge deck 31, a first supporting portion 32 and a second supporting portion 33, wherein the bridge deck 31 is provided with a first end portion and a second end portion, the first end portion is connected with the first supporting portion 32, the second end portion is connected with the second supporting portion 33, the first supporting portion 32 is orthographic projected on the substrate 1 by the first reference electrode 22 and is orthographic projected on the substrate 1 by the second supporting portion 33, the second reference electrode 23 is orthographic projected on the substrate 1 by the second supporting portion 33, a first gap d1 is formed between the bridge deck 31 and the interlayer dielectric layer 4 on the signal electrode 21, the width of an overlapped position of the first end portion and the orthographic projected on the substrate 1 by the first supporting portion 32 in a first direction is a first width W1, the width of an overlapped position of the second end portion and the orthographic projected on the substrate 1 by the second supporting portion 33 in the first direction is a second width W2, the first direction is the direction of the first reference electrode 22 and is directed on the second reference electrode 23, and the first width W1 and the second width W2 are not smaller than half of the first gap d 1.
In the embodiment of the disclosure, since the width of the overlapping position of the first end portion of the bridge deck 31 and the orthographic projection of the first support portion 32 on the substrate 1 in the first direction is the first width W1, the width of the overlapping position of the second end portion and the orthographic projection of the second support portion 33 on the substrate 1 in the first direction is the second width W2, and neither the first width W1 nor the second width W2 is less than half of the first gap d1, i.e., the connection area of the first end portion of the bridge deck 31 and the first support portion 32, nor the connection area of the second end portion and the second support portion 33 is 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 collapse problem of the bridge deck 31.
In some examples, the deck 31 of the membrane bridge structure 3 has a thickness not less than the first gap d1. Further, the thickness of the first supporting portion 32 and the second supporting portion 33 is equal to the thickness d2 of the bridge deck 31, that is, the thickness of both is not smaller than the first gap d1. 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 will be appreciated 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, so that the first supporting portion 32 and the second supporting portion 33 will not protrude locally to be abutted against the bridge deck 31, and the first supporting portion 32 and the second supporting portion 33 are both abutted against the bridge deck 31 surface-to-surface, so that bridge collapse can be effectively avoided.
In forming the film bridge structure 3, the thickness of the conductive film forming the film bridge structure 3 may be set according to the material rigidity and strength of the conductive film. The thickness of the conductive film formed is preferably 20% or more thicker than the thickness of the sacrificial layer 8. In theory, the thicker the thickness of the conductive film layer, the better the stability of the film bridge structure 3, but considering the cost and the process implementation, the thickness of the film bridge structure 3 needs to be specifically set according to the specific situation.
In some examples, FIG. 4 is a cross-sectional view of another MEMS switch of an embodiment of the present disclosure, as shown in FIG. 4, which includes not only the structure described above, but also a first stiffener 51 and/or a second stiffener 52. The drawings of the embodiments of the present disclosure take only the MEMS switch as an example, which includes both the first stiffener 51 and the second stiffener 52. Wherein the first reinforcement member 51 is disposed on a side of the film bridge structure 3 facing away from the substrate 1, and the first reinforcement member 51 is located at a connection position between the first end portion of the bridge deck 31 and the first support portion 32, and an orthographic projection of the first reinforcement member 51 on the substrate 1 covers at least an orthographic projection of the connection position between the first end portion of the bridge deck 31 and the first support portion 32 on the substrate 1. The connection position of the first end portion of the bridge deck 31 and the first support portion 32 refers to a position where the first end portion of the bridge deck 31 and the first support portion 32 overlap in orthographic projection on the substrate 1.
The second reinforcement 52 is arranged on the side of the film bridge structure 3 facing away from the substrate 1, and the second reinforcement is located at the connection position of the second end portion and the second support portion 33, and the orthographic projection of the second reinforcement 52 on the substrate 1 covers at least the orthographic projection of the connection position of the second end portion of the bridge surface 31 and the second support portion 33 on the substrate 1. The connection position of the second end portion of the bridge deck 31 and the second support portion 33 refers to a position where the second end portion of the bridge deck 31 and the second support portion 33 overlap in orthographic projection on the substrate 1. In this case, by adding the first reinforcement 51 and the second reinforcement 52, further stability of the film bridge structure 3 is provided, and the problem that the deck 31 of the film bridge structure 3 collapses due to stress and electrostatic force is avoided.
Further, the first reinforcement includes a first reinforcement portion 511, a second reinforcement portion 512, and a first connection portion 513 connecting the first reinforcement portion 511 and the second reinforcement portion 512. The first reinforcement portion 511 is located at a side of the first end portion facing away from the substrate 1, the second reinforcement portion 512 is located at a side of the first support portion 32 facing away from the substrate 1, and an orthographic projection of an end of the first reinforcement portion 511 facing away from the first connection portion 513 on the substrate 1 is located between orthographic projections of the first reference electrode 22 and the signal electrode 21 on the substrate 1. When the second reinforcement member 52 is used, the second reinforcement member 52 includes a third reinforcement portion 521, a fourth reinforcement portion 522, and a second connection portion 523 connecting the third reinforcement portion and the fourth reinforcement portion 522, wherein the third reinforcement portion 521 is located at a side of the second end portion facing away from the substrate 1, the fourth reinforcement portion 522 is located at a side of the second support portion 33 facing away from the substrate 1, and an orthographic projection of an end of the third reinforcement portion 521 facing away from the second connection portion 523 on the substrate 1 is located between orthographic projections of the second reference electrode 23 and the signal electrode 21 on the substrate 1. In this case, the orthographic projections of the first reinforcement member 51 and the second reinforcement member 52 on the substrate base plate 1 do not overlap with the orthographic projections of the signal electrodes 21 on the substrate base plate 1.
Further, fig. 5 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure, and as shown in fig. 5, both the first stiffener and the second stiffener may be formed as an integral structure with the membrane bridge structure 3, that is, the first stiffener 51 and the second stiffener 52 may be formed simultaneously with the formation of the membrane bridge structure 3. In this case, it is equivalent to further increasing the thickness of the first support portion 32 and the second support portion 33, so that a more stable support can be provided for the deck 31, and thus the problem of collapse can be effectively avoided.
When the first reinforcing member 51 and the second reinforcing member 52 are both integrally formed with the film bridge structure 3, the first reinforcing member 51, the second reinforcing member 52, and the film bridge structure 3 may be manufactured in one process. For example, a conductive film with a relatively larger thickness is sputtered or electroplated on the sacrificial layer 8, and then the middle area of the bridge deck 31 to be formed is etched, so that the first reinforcement 51, the second reinforcement 52 and the membrane bridge structure 3 are formed integrally (for a specific forming process, please refer to a subsequent preparation method).
Of course, the first reinforcement member 51 and the second reinforcement member 52 may be made of the same material as the film bridge structure 3, and in this case, the first reinforcement member 51 and the second reinforcement member 52 may be made by a single process, and the film bridge structure 3 may be made by a single process. For example, the film bridge structure 3 is formed on the sacrificial layer 8 first, followed by the formation of the first stiffener 51 and the second stiffener 52.
Further, when the first reinforcement 51 and the second reinforcement 52 are prepared independently from the film bridge structure 3, in order to avoid the problem of slit cracking caused by the damage to the flatness of the bridge deck 31 of the film bridge structure 3 when etching the bridge deck 31 to form the first reinforcement and the second reinforcement, and weakening the stress bearing capability of the film bridge structure 3, fig. 6 is a cross-sectional view of another MEMS switch according to an embodiment of the present disclosure, as shown in fig. 6, a protective layer 6 is formed on a side of the bridge deck 31 of the film bridge structure 3 facing away from the substrate 1, and the first reinforcement and the second reinforcement are disposed on a side of the protective layer 6 facing away from the substrate 1 (refer to the following preparation process steps of the structure).
When the MEMS switch includes the first reinforcement 51 and the second reinforcement 52, if the first reinforcement 511 on the deck 31 of the first reinforcement 51 is at a right angle to the plane of the deck 31, the stress will be concentrated at the right angle, and similarly, if the third reinforcement 521 on the deck 31 of the second reinforcement is at a right angle to the plane of the deck 31, the stress will be concentrated at the right angle. To alleviate this problem, in some examples, fig. 7 is a schematic diagram of connection positions of the bridge deck and the first reinforcement of the MEMS switch according to the embodiment of the present disclosure, and as shown in fig. 7, the first reinforcement 511 has a first side S1 disposed opposite to the third reinforcement 521, and a second side connected to the first connection portion opposite to the first side S1, and the third reinforcement 521 has a third side disposed opposite to the first reinforcement 511, and a fourth side opposite to the third side and connected to the second connection portion 523. The first side surface may be an arc surface, and the third side surface may be an arc surface, so that the plane from the first side surface S1 of the first reinforcement portion 511 to the deck 31 is a smooth transition, and the problem of stress concentration is relieved. Of course, in other examples, fig. 8 is another schematic diagram of connection positions between the bridge deck and the first reinforcement of the MEMS switch according to the embodiment of the present disclosure, as shown in fig. 8, the first side S1 of the first reinforcement portion 511 may be designed as an inclined plane with respect to the plane of the bridge deck 31, such that the dihedral angle formed by the first side S1 and the plane of the bridge deck 31 is an obtuse angle, and similarly, the third side of the third reinforcement portion 521 may be designed as an inclined plane with respect to the plane of the bridge deck 31, such that the dihedral angle formed by the third side and the plane of the bridge deck 31 is an obtuse angle, and thus, the transition between the first side and the plane of the bridge deck 31 and the plane of the third side and the plane of the bridge deck 31 may be provided, so that the problem of stress concentration may be alleviated. Further, the dihedral angles formed by the first side S1 and the plane where the bridge deck 31 is located, and the dihedral angles formed by the third side and the plane where the bridge deck 31 is located may be about 110 ° to 140 °.
In some examples, the substrate 1 may be a glass substrate, regardless of the MEMS switch using any of the structures described above. Compared with a silicon-based MEMS switch, the manufacturing of the MEMS switch with the glass substrate can be free from the limitation of a wafer line, so that the preparation of the MEMS switch with a large area is realized, and the production cost is greatly reduced.
Correspondingly, for the MEMS switch of the above example, the embodiment of the disclosure also provides a preparation method of the MEMS switch, and the method can be used for preparing any MEMS switch.
Specifically, the preparation method of the MEMS switch comprises the following steps:
S01, providing a substrate base plate 1;
s02, forming a signal electrode 21, a first reference electrode 22 and a second reference electrode 23 on the substrate 1, wherein the first reference electrode 22 and the second reference electrode 23 are positioned on two sides of the extending direction of the signal electrode 21;
S03, forming an interlayer dielectric layer 4 on one side of the layer where the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 are located, which is away from the substrate 1, wherein the interlayer dielectric layer 4 at least covers one side of the signal electrode 21, which is away from the substrate 1;
S04, forming a film bridge structure 3 on one side of the interlayer dielectric layer 4 away from the substrate 1, wherein,
The film bridge structure 3 comprises a bridge deck 31, a first supporting part 32 and a second supporting part 33, wherein the bridge deck 31 is provided with a first end part and a second end part, the first end part is connected with the first supporting part 32, the second end part is connected with the second supporting part 33, the first supporting part 32 is orthographic projected on the substrate 1 on the orthographic projection of the first reference electrode 22 on the substrate 1, the second supporting part 33 is orthographic projected on the substrate 1 on the orthographic projection of the second reference electrode 23 on the substrate 1, and a first gap d1 is reserved 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 part and the orthographic projection of the first support part 32 on the substrate 1 in the first direction is a first width W1, the width of the overlapping position of the second end part and the orthographic projection of the second support part 33 on the substrate 1 in the first direction is a second width W2, the first direction is the direction that the first reference electrode 22 points to the second reference electrode 23, and the first width W1 and the second width W2 are not less than half of the first gap d1.
In order to make the preparation method of the MEMS switch according to the embodiments of the present disclosure more clear, the following description is made with reference to specific examples.
Example one fig. 9 is a flowchart of an example one of a method for manufacturing a MEMS switch according to an embodiment of the present disclosure, and as shown in fig. 9, the thickness of the bridge floor 31 of the membrane bridge structure 3 is not less than the first gap d1, for example, the thickness of each of the first support portion 32 and the second support portion 33 is equal to the thickness of the bridge floor 31 structure, and the thickness of the bridge floor 31 structure is equal to the first gap d 1. The preparation method for the MEMS switch in the case specifically comprises the following steps:
S11, providing a substrate base plate 1.
In some examples, the substrate 1 includes, but is not limited to, a glass substrate, and in the embodiments of the present disclosure, the substrate 1 is described using a glass substrate as an example.
S12, a signal electrode 21, a first reference electrode 22, and a second reference electrode 23 are formed on the substrate 1.
In some examples, step S12 may specifically include forming a first conductive film by sputtering or electroplating, and patterning to form a first electrode including the signal electrode 21, the first reference electrode 22, and the second reference electrode 23.
For example, when the first conductive film is formed by electroplating, taking copper Cu as an example of the material of the first conductive film, the step S12 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the first seed layer by sputtering, 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. The first plating method is an additive method, after the first seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form a patterned signal electrode 21, a first reference electrode 22 and a second reference electrode 23. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
And S13, forming an interlayer dielectric layer 4 on the side, away from the substrate 1, of the layer where the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 are located, wherein the interlayer dielectric layer 4 at least covers the signal electrode 21.
In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide and silicon nitride, and the thickness is 0.1-0.2 μm. Step S13 may specifically include performing deposition to form the interlayer dielectric layer 4 by using standard processes such as ion-enhanced chemical vapor deposition (PECVD), and performing patterning to form a pattern including the interlayer dielectric layer 4.
And S14, forming a sacrificial layer 8 on one side of the interlayer dielectric layer 4 away from the substrate 1.
In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, etc., and the thickness of the sacrificial layer 8 is around 1.5 μm. Taking the photoresist as an example of the sacrificial layer 8, step S14 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 facing away from the substrate 1, exposing with a corresponding mask, denaturing the photoresist irradiated with ultraviolet light, developing with an acetone solution as a developing solution, and developing and removing the denatured photoresist to form the pattern including the sacrificial layer 8.
And S15, forming a film bridge structure 3 on the side of the sacrificial layer 8 away from the substrate 1.
In some examples, step S15 may specifically include forming a second conductive film by sputtering or electroplating, and patterning to form a pattern including the film bridge structure 3.
For example, when the second conductive film is formed by electroplating, taking copper Cu as an example of the material of the second conductive film, the step S152 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the second seed layer by sputtering, then depositing thick copper of about 1.5 μm by electroplating, and then forming the film bridge structure 3 by exposure and development etching. The first electroplating method is an addition method, after the second seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form the patterned membrane bridge structure 3. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
S16, releasing the sacrificial layer 8.
In some examples, a wet etch may be used to release the sacrificial layer 8 in step S16, for example using an isopropanol solution to release the sacrificial layer 8.
Thus, the preparation of the MEMS switch is completed. In this production method, the thickness of the sacrificial layer 8, i.e. the first gap d1 between the bridge floor 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, i.e. the first gap d1 is around 1.5 μm. The bridge deck 31 of the membrane bridge structure 3 formed by the preparation method has a first width W1 at the first end and the first support portion 32, and a second width W2 at the second end and the second support portion 33, wherein the first width W1 and the second width W2 are about 0.8 μm.
Example two fig. 10 is a flowchart of an example two of a method for manufacturing a MEMS switch according to an embodiment of the disclosure, referring to fig. 10, a first stiffener and a second stiffener are added as compared with example one, and the method for manufacturing a MEMS switch with such a structure specifically includes the following steps:
S21, providing a substrate base plate 1.
In some examples, the substrate 1 includes, but is not limited to, a glass substrate, and in the embodiments of the present disclosure, the substrate 1 is described using a glass substrate as an example.
S22, a signal electrode 21, a first reference electrode 22, and a second reference electrode 23 are formed on the substrate 1.
In some examples, step S22 may include forming a first conductive film by sputtering or electroplating, and patterning to form a first electrode including the signal electrode 21, the first reference electrode 22, and the second reference electrode 23.
For example, when the first conductive film is formed by electroplating, taking copper Cu as an example of the material of the first conductive film, the step S22 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the first seed layer by sputtering, 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. The first plating method is an additive method, after the first seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form a patterned signal electrode 21, a first reference electrode 22 and a second reference electrode 23. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
S23, forming an interlayer dielectric layer 4 on the side, away from the substrate 1, of the layer where the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 are located, wherein the interlayer dielectric layer 4 at least covers the signal electrode 21.
In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide and silicon nitride, and the thickness is 0.1-0.2 μm. Step S23 may specifically include performing deposition to form the interlayer dielectric layer 4 by standard processes such as ion-enhanced chemical vapor deposition (PECVD), and performing patterning to form a pattern including the interlayer dielectric layer 4.
And S24, forming a sacrificial layer 8 on the side of the interlayer dielectric layer 4 away from the substrate 1.
In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, etc., and the thickness of the sacrificial layer 8 is around 1.5 μm. Taking the photoresist as an example of the sacrificial layer 8, the step S24 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 away from the substrate 1, exposing with a corresponding mask, denaturing the photoresist irradiated with ultraviolet light, developing with an acetone solution as a developing solution, and developing and removing the denatured photoresist to form the pattern including the sacrificial layer 8.
And S25, forming a film bridge structure 3 on the side of the sacrificial layer 8 away from the substrate 1.
In some examples, step S25 may specifically include forming a second conductive film by sputtering or electroplating, and patterning to form a pattern including the film bridge structure 3.
For example, when the second conductive film is formed by electroplating, taking copper Cu as an example of the material of the second conductive film, the step S25 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the second seed layer by sputtering, then depositing thick copper of about 1.5 μm by electroplating, and then etching by exposure and development to form the film bridge structure 3. The first electroplating method is an addition method, after the second seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form the patterned membrane bridge structure 3. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
S26, forming a first reinforcement and a second reinforcement on one side of the film bridge structure 3, which faces away from the substrate 1.
In some examples, step S26 may include forming a third conductive film in a manner including, but not limited to, sputtering, and then forming a pattern including the first reinforcement and the second reinforcement through photolithography and etching processes.
S27, releasing the sacrificial layer 8.
In some examples, a wet etch may be used to release the sacrificial layer 8 in step S27, for example using an isopropanol solution to release the sacrificial layer 8.
Thus, the preparation of the MEMS switch is completed. In this production method, the thickness of the sacrificial layer 8, i.e. the first gap d1 between the bridge floor 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, i.e. the first gap d1 is around 1.5 μm. The bridge deck 31 of the membrane bridge structure 3 formed by the preparation method has a first width W1 at the first end and the first support portion 32, and a second width W2 at the second end and the second support portion 33, wherein the first width W1 and the second width W2 are about 0.8 μm.
Example III referring to FIG. 11, in comparison with example II, in which the first stiffener and the second stiffener are formed with the membrane bridge structure 3 in one process, the method for manufacturing the MEMS switch of the present disclosure specifically includes the following steps:
s31, providing a substrate 1.
In some examples, the substrate 1 includes, but is not limited to, a glass substrate, and in the embodiments of the present disclosure, the substrate 1 is described using a glass substrate as an example.
S32, a signal electrode 21, a first reference electrode 22, and a second reference electrode 23 are formed on the substrate 1.
In some examples, step S32 may include forming a first conductive film by sputtering or electroplating, and patterning to form a first electrode including the signal electrode 21, the first reference electrode 22, and the second reference electrode 23.
For example, when the first conductive film is formed by electroplating, taking copper Cu as an example of the material of the first conductive film, the step S32 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the first seed layer by sputtering, 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. The first plating method is an additive method, after the first seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form a patterned signal electrode 21, a first reference electrode 22 and a second reference electrode 23. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
And S33, forming an interlayer dielectric layer 4 on the side, away from the substrate 1, of the layer where the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 are located, wherein the interlayer dielectric layer 4 at least covers the signal electrode 21.
In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide and silicon nitride, and the thickness is 0.1-0.2 μm. Step S33 may specifically include performing deposition to form the interlayer dielectric layer 4 by using standard processes such as ion-enhanced chemical vapor deposition (PECVD), and performing patterning to form a pattern including the interlayer dielectric layer 4.
And S34, forming a sacrificial layer 8 on one side of the interlayer dielectric layer 4 away from the substrate 1.
In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, etc., and the thickness of the sacrificial layer 8 is around 1.5 μm. Taking the photoresist as an example of the sacrificial layer 8, the step S34 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 away from the substrate 1, exposing with a corresponding mask, denaturing the photoresist irradiated with ultraviolet light, developing with an acetone solution as a developing solution, and developing and removing the denatured photoresist to form the pattern including the sacrificial layer 8.
S35, forming a film bridge structure 3, a first stiffener and a second stiffener on a side of the sacrificial layer 8 facing away from the substrate 1.
In some examples, step S35 may specifically include forming a second conductive film by sputtering or electroplating, and patterning to form a pattern including the film bridge structure 3, the first reinforcement member, and the second reinforcement member.
For example, when the second conductive film is formed by electroplating, taking copper Cu as an example of a material of the second conductive film, the step S35 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the second seed layer by sputtering, depositing about 1.8-2.0 μm thick copper by electroplating, forming a semi-finished product of the film bridge structure 3, the first reinforcement and the second reinforcement by exposure and development etching, and finally etching the position of the semi-finished product of the film bridge structure 3 corresponding to the bridge deck 31 to form the bridge deck 31 of the film bridge. The first electroplating method is an addition method, after the second seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form the patterned membrane bridge structure 3. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
S36, releasing the sacrificial layer 8.
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.
Thus, the preparation of the MEMS switch is completed. In this production method, the thickness of the sacrificial layer 8, i.e. the first gap d1 between the bridge floor 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, i.e. the first gap d1 is around 1.5 μm. The bridge deck 31 of the membrane bridge structure 3 formed by the preparation method has a first width W1 at the first end and the first support portion 32, and a second width W2 at the second end and the second support portion 33, wherein the first width W1 and the second width W2 are about 1 μm.
Referring to fig. 12, a protective layer 6 is added between the membrane bridge and the first reinforcement member and the second reinforcement member, and the preparation method of the MEMS switch with the structure specifically comprises the following steps:
S41, providing a substrate 1.
In some examples, the substrate 1 includes, but is not limited to, a glass substrate, and in the embodiments of the present disclosure, the substrate 1 is described using a glass substrate as an example.
S42, the signal electrode 21, the first reference electrode 22, and the second reference electrode 23 are formed on the substrate 1.
In some examples, step S42 may include forming a first conductive film by sputtering or electroplating, and patterning to form a first electrode including the signal electrode 21, the first reference electrode 22, and the second reference electrode 23.
For example, when the first conductive film is formed by electroplating, taking copper Cu as an example of the material of the first conductive film, the step S42 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the first seed layer by sputtering, 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. The first plating method is an additive method, after the first seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form a patterned signal electrode 21, a first reference electrode 22 and a second reference electrode 23. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
And S43, forming an interlayer dielectric layer 4 on the side, away from the substrate 1, of the layer where the signal electrode 21, the first reference electrode 22 and the second reference electrode 23 are located, wherein the interlayer dielectric layer 4 at least covers the signal electrode 21.
In some examples, the material of the interlayer dielectric layer 4 includes, but is not limited to, silicon oxide and silicon nitride, and the thickness is 0.1-0.2 μm. Step S43 may specifically include performing deposition to form the interlayer dielectric layer 4 by standard processes such as ion-enhanced chemical vapor deposition (PECVD), and performing patterning to form a pattern including the interlayer dielectric layer 4.
And S44, forming a sacrificial layer 8 on the side of the interlayer dielectric layer 4 away from the substrate 1.
In some examples, the material of the sacrificial layer 8 includes, but is not limited to, photoresist or polyimide, etc., and the thickness of the sacrificial layer 8 is around 1.5 μm. Taking the photoresist as an example of the sacrificial layer 8, step S44 may include spin-coating the photoresist on the side of the interlayer dielectric layer 4 facing away from the substrate 1, exposing with a corresponding mask, denaturing the photoresist irradiated with ultraviolet light, developing with an acetone solution as a developing solution, and developing and removing the denatured photoresist to form the pattern including the sacrificial layer 8.
S45, forming a film bridge structure 3 on a side of the sacrificial layer 8 facing away from the substrate 1.
In some examples, step S45 may specifically include forming a second conductive film by sputtering or electroplating, and patterning to form a pattern including the film bridge structure 3.
For example, when the second conductive film is formed by electroplating, taking copper Cu as an example of the material of the second conductive film, the step S45 may specifically include sequentially forming MO/Cu or Ti/Cu metal as the second seed layer by sputtering, then depositing thick copper of about 1.5 μm by electroplating, and then forming the film bridge structure 3 by exposure and development etching. The first electroplating method is an addition method, after the second seed layer is deposited, an electroplated PR retaining wall is formed through a photoetching process, then electroplating is carried out, and after electroplating is completed, a Strip and copper etching process are carried out to form the patterned membrane bridge structure 3. The second is a subtractive method, in which after the first seed layer is deposited, electroplating is directly performed to form copper of a certain thickness, and patterning is then performed by photolithography and etching processes.
And S46, forming a protective layer 6 on the side of the film bridge structure 3, which is away from the substrate 1.
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.
S47, forming a first reinforcement and a second reinforcement on a side of the protective layer 6 facing away from the substrate 1.
In some examples, step S46 may specifically include forming a third conductive film in a manner including, but not limited to, sputtering, and then forming a pattern including the first reinforcement and the second reinforcement through photolithography and etching processes.
S48, releasing the sacrificial layer 8.
In some examples, a wet etch may be used to release the sacrificial layer 8 in step S48, for example using an isopropanol solution to release the sacrificial layer 8.
Thus, the preparation of the MEMS switch is completed. In this production method, the thickness of the sacrificial layer 8, i.e. the first gap d1 between the bridge floor 31 of the membrane bridge structure 3 and the interlayer dielectric layer 4, i.e. the first gap d1 is around 1.5 μm. The bridge deck 31 of the membrane bridge structure 3 formed by the preparation method has a first width W1 at the first end and the first support portion 32, and a second width W2 at the second end and the second support portion 33, wherein the first width W1 and the second width W2 are about 0.8 μm.
A second example is that fig. 13 is a cross-sectional view of another MEMS switch of the disclosed embodiment, and that the membrane bridge structure 3 of the MEMS switch is a single-armed bridge as shown in fig. 13, which is substantially identical to the structure of the first example, except that the structure comprises only one support 30. For such a MEMS switch it is also possible to form the contact member 7 on the side of the second reference electrode 23 facing away from the substrate 1, so that when the bridge deck 31 is pulled down, the contact member 7 is brought into conduction with the second reference electrode 23, enabling the switch to be opened. The other structures may be the same as those of the first example, so that the description thereof will not be repeated.
In addition, for such a structural MEMS switch, when the 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, so that a description thereof will not be repeated.
Accordingly, the preparation method of the MEMS switch with the structure may also be the preparation method in the first example, so that the description thereof will not be repeated here.
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
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| US6630871B2 (en) * | 2001-09-28 | 2003-10-07 | Intel Corporation | Center-mass-reduced microbridge structures for ultra-high frequency MEM resonator |
| CN100403476C (en) * | 2004-09-27 | 2008-07-16 | 东南大学 | RF microelectromechanical single-pole double-throw membrane switch and method of manufacturing the same |
| CN100389474C (en) * | 2006-04-17 | 2008-05-21 | 东南大学 | Radio-frequency micro-electronic mechanical double-film parallel capacitive type switch and preparation method thereof |
| JP5408937B2 (en) * | 2007-09-25 | 2014-02-05 | キヤノン株式会社 | Electromechanical transducer and manufacturing method thereof |
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