CN115249601A

CN115249601A - Micro-electromechanical system switch and preparation method thereof

Info

Publication number: CN115249601A
Application number: CN202210908030.7A
Authority: CN
Inventors: 谭秋云; 孟虎
Original assignee: BOE Technology Group Co Ltd
Current assignee: BOE Technology Group Co Ltd
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2022-10-28

Abstract

The embodiments of the present application provide a mems switch and a method of fabricating a mems switch. The MEMS switch includes: a substrate; a signal line disposed on one side of the substrate; the switch beam is positioned on one side of the signal line far away from the substrate, the switch beam is provided with an accommodating hole, and the orthographic projection of the accommodating hole on the substrate is positioned in the orthographic projection of the signal line on the substrate; and the conductive part is connected with the signal wire and positioned between the signal wire and the switch beam, and the orthographic projection of the conductive part on the substrate is positioned in the orthographic projection of the accommodating hole on the substrate. The embodiment of the application can effectively improve the capacitance ratio of the off-state capacitance to the on-state capacitance, thereby improving the radio frequency performance of the micro electromechanical system switch.

Description

Micro-electromechanical system switch and preparation method thereof

Technical Field

The present application relates to the field of mems technology, and more particularly, to a mems switch and a method for fabricating a mems switch.

Background

Compared with the traditional switch, the Micro Electro Mechanical System (MEMS) has the advantages of low loss, low power consumption, good linearity, high isolation, small size, easy integration and the like, avoids the problems of ohmic loss and I-V nonlinearity of the traditional Field Effect Transistor (FET) and pin switch caused by P-N junction and metal semiconductor junction, overcomes the parasitic influence caused by large volume, large power consumption and element connection wire of the traditional external discrete element, and can replace the traditional semiconductor device to be applied to a microwave System.

The insertion loss and isolation of the mems switch is related to the magnitude of the coupling capacitance ratio of the switch when it is turned on and off. In order to reduce the insertion loss when the switch is turned on, the coupling capacitance Con (on-state capacitance) of the MEMS switch in the on-state should be as small as possible; in order to improve the isolation of the MEMS switch when it is turned off, the coupling capacitance Coff (off-state capacitance) of the MEMS switch in the off state should be as large as possible. Therefore, the larger the capacitance ratio Coff/Con of the MEMS switch, the better the radio frequency performance thereof.

Therefore, it is desirable to provide a mems switch that effectively increases the capacitance ratio Coff/Con, thereby improving the rf performance of the mems switch.

Disclosure of Invention

The application provides a micro-electromechanical system switch and a preparation method of the micro-electromechanical system switch aiming at the defects of the existing mode, and can effectively improve the capacitance ratio, so that the radio frequency performance of the micro-electromechanical system switch is improved.

In a first aspect, embodiments of the present application provide a micro-electromechanical system switch comprising: a substrate; a signal line disposed on one side of the substrate; the switch beam is positioned on one side of the signal line far away from the substrate, the switch beam is provided with an accommodating hole, and the orthographic projection of the accommodating hole on the substrate is positioned in the orthographic projection of the signal line on the substrate; and the conductive part is connected with the signal wire and positioned between the signal wire and the switch beam, and the orthographic projection of the conductive part on the substrate is positioned in the orthographic projection of the accommodating hole on the substrate.

Optionally, the number of the conductive parts and the accommodating holes is one; or the number of the conductive parts and the accommodating holes is at least two, the conductive parts and the accommodating holes are arranged in a one-to-one correspondence manner, the at least two conductive parts are arranged in an array manner, and the at least two accommodating holes are arranged in an array manner.

Optionally, the cross section of the conductive part is circular or polygonal; and/or the cross-sectional shape of the accommodating hole is the same as the cross-sectional shape of the conductive part; wherein the cross-section is parallel to the substrate.

Optionally, the optical device further comprises a dielectric layer, wherein the dielectric layer is positioned on one side of the substrate and covers at least part of the signal line; the dielectric layer is provided with a through hole, one end of the conductive part is connected with the signal line, and the other end of the conductive part penetrates out of the through hole and protrudes out of the dielectric layer.

Optionally, the optical device further includes a dielectric layer located on one side of the substrate and covering a part of the signal line; the dielectric layer is provided with a contact hole, the conductive part is arranged in the contact hole, one end of the conductive part is connected with the signal line, and the other end of the conductive part is flush with the outer surface of one side of the dielectric layer far away from the substrate or lower than the outer surface of one side of the dielectric layer far away from the substrate; the size of the accommodation hole is larger than the sum of the sizes of the conductive part and the dielectric layer along the direction parallel to the substrate.

Optionally, the signal line further comprises a ground line, the ground line is located on one side of the signal line, and the ground line and the signal line are arranged at intervals in an insulating manner; one end of the switch beam is connected with the ground wire; and/or further comprising an insulating layer disposed between the substrate and the signal line.

In a second aspect, embodiments of the present application provide a method of fabricating a MEMS switch, comprising: providing a substrate, and preparing a signal line on the substrate; preparing a conductive part on one side of the signal wire far away from the substrate; and preparing a switch beam on one side of the conductive part, which is far away from the substrate, wherein the switch beam is provided with a containing hole, the orthographic projection of the containing hole on the substrate is positioned in the orthographic projection of the signal line on the substrate, and the orthographic projection of the conductive part on the substrate is positioned in the orthographic projection of the containing hole on the substrate.

Optionally, before the signal line is prepared on the substrate, the method further includes: preparing an insulating layer on a substrate; preparing a signal line on a substrate, comprising: two ground wires are prepared on two sides of the signal wire, the signal wire is positioned between the two ground wires, and the signal wire and the ground wires are separated and insulated.

Optionally, the preparing the conductive part on the side of the signal line far away from the substrate includes: manufacturing a dielectric layer on one side of the signal line, which is far away from the substrate, by a composition process, wherein the dielectric layer is provided with a through hole so as to expose the signal line; and manufacturing a conductive part on one side of the dielectric layer far away from the substrate by a composition process, wherein the conductive part is filled in the through hole, and part of the conductive part protrudes out of the dielectric layer.

Optionally, preparing the switch beam on a side of the conductive portion away from the substrate comprises: preparing a sacrificial layer on one side of the conductive part far away from the substrate, wherein the sacrificial layer covers the conductive part, the signal line and the partial ground wire; manufacturing a conducting layer on one side of the sacrificial layer, which is far away from the substrate, by a composition process, wherein the conducting layer covers the sacrificial layer and is connected with the two ground wires; and carrying out a patterning process on the conductive layer to form a containing hole, and removing the sacrificial layer to form the switch beam.

The beneficial technical effects brought by the technical scheme provided by the embodiment of the application comprise:

according to the micro-electromechanical system switch provided by the embodiment of the application, when the micro-electromechanical system switch is in an on state, as the switch beam and the conductive part are provided with the interval, and the conductive part is connected with the signal line and is positioned between the signal line and the switch beam, the switch beam and the signal line are also provided with the interval, and an on-state capacitor is formed between the switch beam and the signal line; when the micro-electromechanical system switch is in an off state, because the orthographic projection of the conductive part on the substrate is positioned in the orthographic projection of the accommodating hole on the substrate, and the conductive part penetrates through the accommodating hole, a first off-state capacitor is formed between the switch beam and the signal line at the moment, and a second off-state capacitor is formed between the conductive part and the switch beam. According to the embodiment of the application, the second off-state capacitor is introduced by arranging the conductive part and the containing hole, so that the off-state capacitor is effectively increased, the capacitance ratio of the off-state capacitor to the on-state capacitor can be effectively improved, and the radio frequency performance of the micro electromechanical system switch is further improved.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of a typical capacitive MEMS switch;

FIG. 2 is an equivalent circuit diagram of a typical capacitive MEMS switch;

FIG. 3 is a schematic diagram of a MEMS switch according to an embodiment of the present application;

fig. 4 is an equivalent circuit diagram of an on state of a mems switch according to an embodiment of the present application;

fig. 5 is an equivalent circuit diagram of an off state of a mems switch according to an embodiment of the present application;

fig. 6 is a cross-sectional view of an on state of a mems switch according to an embodiment of the present application;

fig. 7 is a cross-sectional view of an off state of a mems switch according to an embodiment of the present application;

fig. 8 is a schematic diagram of a second off-state capacitor in the off-state of a mems switch according to an embodiment of the present application;

fig. 9 is a schematic diagram of a mems switch according to another embodiment of the present application;

fig. 10 is a schematic diagram of a mems switch according to yet another embodiment of the present application;

fig. 11 is a flow chart of a method of fabricating a mems switch according to an embodiment of the present disclosure;

fig. 12-18 are schematic structural diagrams of different processes in a method for fabricating a mems switch according to an embodiment of the present disclosure.

Reference numerals are as follows:

1-ground wire; 2-a signal line; 3-a substrate; 4-a dielectric layer; 5-switch beam body; 6-a switch beam support structure; 7-an insulating layer; 8-a containing hole; 9-a conductive portion; 10-a switch beam; 11-sacrificial layer.

Detailed Description

Embodiments of the present application are described below in conjunction with the drawings in the present application. It should be understood that the embodiments set forth below in connection with the drawings are exemplary descriptions for explaining technical solutions of the embodiments of the present application, and do not limit the technical solutions of the embodiments of the present application.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of other features, information, data, steps, operations, elements, components, and/or groups thereof that are already known in the art. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. The term "and/or" as used herein refers to at least one of the items defined by the term, e.g., "a and/or B" may be implemented as "a", or as "B", or as "a and B".

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

The radio frequency switch connects any one or several paths of radio frequency signals through control logic to realize the switching of different types of paths, including the switching of receiving and transmitting, the switching between different frequency bands, and the like, so as to achieve the purposes of sharing antennas and saving the cost of terminal products.

Compared with the traditional switch, the micro electromechanical system switch has the advantages of low loss, low power consumption, good linearity, high isolation, small size, easy integration and the like, avoids the problems of ohmic loss and I-V (current-voltage curve) nonlinearity of the traditional Field Effect Transistor (FET) and pin switch caused by P-N junction and metal semiconductor junction, overcomes the parasitic influence caused by large volume and large power consumption and element connection line of the traditional external discrete element, can replace the traditional semiconductor device to be applied to a microwave system, such as a Radio Frequency (Radio Frequency) MEMS phase shifter, an RF MEMS smart antenna, a T/R (Transmit and Receiver) module, a radar early warning, tactical reconnaissance, satellite networking, guidance and the like, and can also be applied to the civil fields of mobile equipment such as mobile phones, consumer-grade electronic products, navigation systems and the like.

The insertion loss and isolation of a MEMS switch is related to the magnitude of the coupling capacitance ratio of the switch when it is turned on and off. In order to reduce the insertion loss when the switch is turned on, the coupling capacitance Con (on-state capacitance) of the MEMS switch in the on-state should be as small as possible; in order to improve the isolation of the MEMS switch when it is turned off, the coupling capacitance Coff (off-state capacitance) of the MEMS switch in the off state should be as large as possible. Therefore, the larger the capacitance ratio Coff/Con of the MEMS switch, the better its radio frequency performance.

Fig. 1 is a schematic structural diagram of a typical capacitive MEMS switch, where 1 is a ground line, 2 is a signal line, 3 is a substrate, 4 is a dielectric layer, 5 is a switch beam body, 6 is a switch beam support structure, 7 is an insulating layer, and the switch beam body 5 and the switch beam support structure 6 together form a switch beam. The ground line 1, the signal line 2, the substrate 3 and the insulating layer 7 jointly form a Coplanar waveguide (CPW), a radio frequency signal can be transmitted through the Coplanar waveguide, and the switch beam body 5 is bridged over the two ground lines 1 on the two sides of the signal line 2 through the switch beam supporting structure 6. The switching action can be realized by loading a driving voltage between the signal wire 2 and the ground wire 1, when the driving voltage is loaded, the switch beam body 5 moves downwards under the influence of electrostatic force, and when the switch beam body 5 contacts the dielectric layer 4, the interruption of signals is realized. When the driving voltage is removed, the switch beam body 5 returns to the initial position (i.e. the position of the switch beam body 5 in fig. 1), so as to turn on the signal.

In a typical capacitive MEMS switch, the switch beam body 5 and the signal line 2 are equivalent to a parallel plate capacitor, the capacitance between the switch beam body 5 and the signal line 2 is equivalent to a plate capacitor, the dielectric in the capacitor is air and the dielectric layer 4 in the on state, and the dielectric in the capacitor is the dielectric layer 4 in the off state. Fig. 2 is an equivalent circuit diagram of a typical capacitive MEMS switch, where Z0 is the input/output impedance of CPW, con is the on-state capacitance between the switch beam body 5 and the signal line 2 when no driving voltage is applied, and Coff is the off-state capacitance between the switch beam body 5 and the signal line 2 when a driving voltage is applied. R is the equivalent resistance between the switch beam body 5 and the signal line 2, and L is the equivalent inductance between the switch beam body 5 and the signal line 2.

The off-state capacitance Coff and the on-state capacitance Con of a typical capacitive MEMS switch are respectively:

wherein epsilon 0 is a vacuum dielectric constant, epsilon r is a relative dielectric constant of the dielectric layer, d is a thickness of the dielectric layer, g is a distance between the dielectric layer and the switch beam body, and S0 is a projection overlapping area of the switch beam body, the dielectric layer and the signal line.

Capacitance ratio of typical capacitive MEMS switches

Comprises the following steps:

from the above formula, it can be seen that the capacitance ratio can be increased from three aspects of increasing the distance g between the dielectric layer and the switch beam body, increasing the relative dielectric constant epsilonr of the dielectric layer, and reducing the thickness d of the dielectric layer, but these methods introduce other problems, for example, increasing the distance between the switch beam body and the dielectric layer will increase the driving voltage, and reducing the thickness of the dielectric layer will cause the dielectric layer to be easy to generate dielectric breakdown.

In order to solve the above problems, the present application and embodiments of the present application provide a mems switch and a method for manufacturing the mems switch, which can effectively improve a capacitance ratio, thereby improving radio frequency performance of the mems switch.

It should be noted that the capacitance ratio of the MEMS switch in the present application refers to the ratio of the off-state capacitance (Coff) to the on-state capacitance (Con) of the MEMS switch.

The following describes the technical solutions of the present application and how to solve the above technical problems with specific embodiments. It should be noted that the following embodiments may be referred to, referred to or combined with each other, and the description of the same terms, similar features, similar implementation steps, etc. in different embodiments is not repeated.

The embodiment of the present application provides a mems switch, which is schematically shown in fig. 3, 6 to 8, and includes a substrate 3, a signal line 2, a switch beam 10, and a conductive part 9, wherein the signal line 2 is disposed on one side of the substrate 3; the switch beam 10 is positioned on one side of the signal line 2, which is far away from the substrate 3, the switch beam 10 is provided with a containing hole 8, and the orthographic projection of the containing hole 8 on the substrate 3 is positioned in the orthographic projection of the signal line 2 on the substrate 3; the conductive part 9 is connected with the signal line 2 and is positioned between the signal line 2 and the switch beam 10, and the orthographic projection of the conductive part 9 on the substrate 3 is positioned in the orthographic projection of the containing hole 8 on the substrate 3. Wherein: when the mems switch is in the on-state, there is a space between the switch beam 10 and the conductive part 9 (as shown in fig. 6); the conductive portion 9 is disposed through the receiving hole 8 when the mems switch is in the off state (as shown in fig. 7).

Specifically, the specific arrangement manner of the substrate 3 and the signal line 2 in the embodiment of the present application is the same as that in the prior art, and is not described herein again.

In the above arrangement, the substrate 3 has a supporting function for the signal line 2, the switch beam 10, and the conductive portion 9. When the MEMS switch is in an on state, because the switch beam 10 and the conductive part 9 have an interval therebetween, and the conductive part 9 is connected with the signal line 2 and is located between the signal line 2 and the switch beam 10, the switch beam 10 and the signal line 2 also have an interval therebetween, and an on-state capacitor is formed between the switch beam 10 and the signal line 2; when the mems switch is in the off state, since the orthographic projection of the conductive part 9 on the substrate 3 is located in the orthographic projection of the receiving hole 8 on the substrate 3, and the conductive part 9 passes through the receiving hole 8, a first off-state capacitor is formed between the switch beam 10 and the signal line 2, and a second off-state capacitor is formed between the conductive part 9 and the switch beam 10. Compared with a typical capacitive MEMS switch, the embodiment of the present application introduces the second off-state capacitor by providing the conductive part 9 and the containing hole 8, so as to effectively increase the off-state capacitor, thereby effectively improving the capacitance ratio between the off-state capacitor and the on-state capacitor, and further improving the radio frequency performance of the MEMS switch.

Alternatively, as shown in fig. 3, 6 to 8, in the embodiment of the present application, the number of the conductive portion 9 and the accommodating hole 8 is one; the process is simple and easy to manufacture.

Of course, in an alternative embodiment of the present application, the number of the conductive portions and the number of the accommodating holes may be at least two according to actual needs, the conductive portions and the accommodating holes are arranged in a one-to-one correspondence, the at least two conductive portions are arranged in an array, and the at least two accommodating holes are arranged in an array (as shown in fig. 10).

Alternatively, as shown in fig. 3 and 8, in the embodiment of the present application, the cross section of the conductive part 9 is circular; the process is simple and easy to manufacture.

Optionally, in the embodiment of the present application, the conductive portion 9 has a cylindrical structure, and the accommodating hole 8 has a cylindrical hole. Of course, in the optional embodiment of the present application, the conductive portion 9 may also be a truncated cone-shaped structure according to actual needs, and correspondingly, the accommodating hole 8 is a truncated cone-shaped hole.

Alternatively, as shown in fig. 3, in the embodiment of the present application, the cross-sectional shape of the accommodation hole 8 is the same as the cross-sectional shape of the conductive portion 9; this arrangement facilitates the conductive portion 9 to be inserted into the accommodation hole 8. The receiving hole 8 has a circular cross-section.

It should be noted that the cross-section is parallel to the substrate.

Of course, in alternative embodiments of the present application, the cross section of the conductive portion may be polygonal (such as rectangular) or other shapes according to actual needs, and the cross section of the accommodating hole may be adaptively adjusted according to the cross section of the conductive portion (as shown in fig. 9).

Optionally, as shown in fig. 6 to 8, in the embodiment of the present application, the accommodating hole 8 is a through hole; the process is simple and easy to manufacture; meanwhile, the containing hole 8 penetrates through the switch beam 10, when the conducting part 9 penetrates out of the containing hole 8, the corresponding area between the conducting part 9 and the switch beam 10 is the largest, and therefore the capacitance between the conducting part 9 and the switch beam 10 can be the largest, and the arrangement is beneficial to increasing the off-state capacitance.

The application provides a design scheme for improving the capacitance ratio of an MEMS switch, one or more pairs of cylindrical capacitors are introduced between a switch beam 10 and a signal line 2, so that the off-state capacitance can be effectively increased, the on-state capacitance is hardly influenced, and the capacitance ratio Coff/Con of the MEMS switch can be effectively increased. Compared with the traditional mode of improving the capacitance ratio of the MEMS switch, the embodiment of the application has almost no influence on the driving voltage (namely, the driving voltage is not increased) because the distance between the switch beam body and the dielectric layer is not increased, and the dielectric breakdown is not easily caused because the thickness of the dielectric layer is not reduced, and the MEMS switch is simple in process and easy to manufacture.

When a driving voltage is applied to the switch beam 10 and the signal line 2, the switch beam 10 is moved downward by an electrostatic force, and the off-state capacitance Coff is formed by parallel connection of a plate capacitance between the switch beam 10 and the signal line 2 and a cylindrical capacitance between the switch beam 10 and the conductive part 9, so that the off-state capacitance Coff will increase with less influence on the on-state capacitance, thereby increasing the capacitance ratio Coff/Con. Fig. 4 is an equivalent circuit diagram of the MEMS switch in the embodiment of the present application in the on state, and fig. 5 is an equivalent circuit diagram of the MEMS switch in the embodiment of the present application in the off state.

In the embodiment of the present application, the on-state capacitance Con of the MEMS switch satisfies the following relationship:

the capacitance Cp of the first off-state capacitance Coff1 of the MEMS switch satisfies the following relationship:

the capacitance Cc of the second off-state capacitance Coff2 of the MEMS switch satisfies the following relationship:

in the embodiment of the present application, taking the number of the conductive part 9 and the number of the accommodating holes 8 as an example, the off-state capacitance Coff of the MEMS switch satisfies the following relationship:

the capacitance ratio Coff/Con of the MEMS switch satisfies the following relationship:

wherein Con is an on-state capacitor, coff is an off-state capacitor, cp is a capacitance of a first off-state capacitor, cc is a capacitance of a second off-state capacitor, ε 0 is a vacuum dielectric constant, S0 is a projected overlapping area of a switch beam, a dielectric layer and a signal line, g is a distance between the dielectric layer and the switch beam, d is a thickness of the dielectric layer, ε r is a relative dielectric constant of the dielectric layer, dbeam is a thickness of the switch beam, ra is a radius of a containing hole, and rb is a radius of a conductive part.

From the above formula, it can be seen that the capacitance ratio of the MEMS switch in the embodiment of the present application is increased relative to the typical capacitive type MEMS switch

Optionally, as shown in fig. 3, 6 and 7, the mems switch of the embodiment of the present application further includes a dielectric layer 4, where the dielectric layer 4 is located on one side of the substrate 3 and covers at least a portion of the signal line 2; the medium layer 4 is provided with a through hole, one end of the conductive part 9 is connected with the signal line 2, and the other end penetrates through the through hole and protrudes out of the medium layer 4.

Specifically, the specific arrangement manner of the remaining structures of the dielectric layer 4 is the same as that of the prior art except that the dielectric layer 4 is provided with through holes, and the detailed description thereof is omitted here.

In the above arrangement, the through hole is used to avoid the conductive part 9, so that one end of the conductive part 9 is connected to the signal line 2, and the other end of the conductive part 9 protrudes from the dielectric layer 4, so that when the mems switch is in the off state, a second off-state capacitor can be formed between the conductive part 9 and the switch beam 10. When the MEMS switch is in an off state, the conductive part 9 penetrates through the containing hole 8, and the medium of the second off-state capacitor is air.

Of course, in another embodiment of the present application, the mems switch may further include a dielectric layer 4 according to actual needs, the dielectric layer 4 is located on one side of the substrate 3 and covers a part of the signal line 2; the dielectric layer 4 is provided with a contact hole, the conductive part 9 is arranged in the contact hole, one end of the conductive part 9 is connected with the signal wire 2, and the other end of the conductive part is flush with the outer surface of one side of the dielectric layer 4 far away from the substrate 3 or lower than the outer surface of one side of the dielectric layer 4 far away from the substrate 3; the size of the accommodation hole 8 is larger than the sum of the sizes of the conductive portion 9 and the dielectric layer 4 in a direction parallel to the substrate 3. At this time, since the size of the accommodating hole 8 is larger than the sum of the sizes of the conducting part 9 and the dielectric layer 4, when the mems switch is in an off state, the conducting part 9 and a part of the dielectric layer 4 are located in the accommodating hole 8, and at this time, the dielectric of the second off-state capacitor formed by the conducting part 9 and the switch beam 10 is air and the dielectric layer 4, and the number of the dielectric of the second off-state capacitor is increased, which can improve the capacitance of the second off-state capacitor, effectively increase the off-state capacitor, thereby effectively improve the capacitance ratio of the off-state capacitor to the on-state capacitor, and further improve the radio frequency performance of the mems switch.

It should be noted that, if the dielectric layer 4 completely covers the signal line 2, when the size of the accommodating hole 8 is larger than the sum of the sizes of the conductive portion 9 and the dielectric layer 4 along the direction parallel to the substrate 3, on one hand, a capacitance cannot be formed between the signal line 2 and the switch beam 10, and the switch beam 10 cannot approach the signal line 2 even when a driving voltage is applied to the signal line 2, so that the MEMS switch cannot be in an off state, and on the other hand, the dielectric layer 4 may prevent the switch beam 10 from approaching the signal line 2, so that the switch beam 10 and the conductive portion 9 are difficult to cooperate to form a second off-state capacitance. Therefore, in another embodiment of the present application, the dielectric layer 4 only covers part of the signal line 2, and the size of the accommodating hole 8 is larger than the sum of the sizes of the conductive part 9 and the dielectric layer 4 along the direction parallel to the substrate 3, at this time, not only can the switch beam 10 and the signal line 2 cooperate to form a capacitor, and when a driving voltage is applied to the signal line 2, the switch beam 10 can approach the signal line 2 under the action of an electrostatic force, but also can ensure that when the mems switch is in an off state, the conductive part 9 and part of the dielectric layer 4 are both located in the accommodating hole 8, so that the dielectric of the second off-state capacitor is increased, and the capacitance of the second off-state capacitor can be increased.

In the above-described another embodiment of the present application, the dielectric layer 4 has a size smaller than that of the signal line 2 in the direction parallel to the substrate 3, and the dielectric layer 4 can be arranged to cover only a part of the signal line 2.

It should be noted that, in the actual production process, the side edges of the signal line 2 and the dielectric layer 4 may have a slope (for example, in some alternative embodiments, the longitudinal section of the signal line 2 is a rectangle, but the longitudinal section of the signal line obtained in the actual production is a trapezoid, where the longitudinal section is perpendicular to the substrate), and the slope angles of the side edges of the signal line 2 and the dielectric layer 4 are different according to the actual production process, for example, when the signal line 2 or the dielectric layer 4 is formed by wet etching, the slope angle of the side edge of the signal line 2 or the dielectric layer 4 is about 45 °, when the signal line 2 or the dielectric layer 4 is formed by dry etching, the slope angle of the side edge of the signal line 2 or the dielectric layer 4 may reach 60 ° to 70 °, and if the Lift-Off process is used (i.e., the Lift Off process) may be larger.

Optionally, as shown in fig. 3, 6 and 7, the mems switch of the embodiment of the present application further includes a ground line 1, the ground line 1 is located on one side of the signal line 2, and the ground line 1 is spaced from the signal line 2 and is insulated from the signal line 2; one end of the switch beam 10 is connected to the ground line 1.

Alternatively, as shown in fig. 3, 6, and 7, the mems switch of the embodiment of the present application further includes an insulating layer 7, and the insulating layer 7 is disposed between the substrate 3 and the signal line 2. While an insulating layer 7 is arranged between the substrate 3 and the ground line 1.

Specifically, the specific arrangement of the ground line 1, the signal line 2, the substrate 3 and the insulating layer 7 is the same as that of the prior art, and is not described herein again.

Optionally, in the embodiment of the present application, the switch beam 10 has elasticity; the switch beam 10 comprises a switch beam body 5 and a switch beam supporting structure 6 which are connected, and the switch beam body 5 is bridged on the two ground wires 1 positioned at two sides of the signal wire 2 through the switch beam supporting structure 6. When a driving voltage is loaded, the switch beam body 5 can move from an initial position (at the moment, the MEMS switch is in an open state) to the signal line 2 under the action of electrostatic force; when the driving voltage stops being applied, the switch beam body 5 can be restored to the initial position under the action of the elasticity of the switch beam body 5 itself. Optionally, the switch beam body 5 and the switch beam support structure 6 are an integrally formed structure.

Specifically, in the embodiment of the present application, except that the switch beam body 5 is provided with the accommodating hole 8, the other structures of the switch beam body 5 and the specific arrangement manner of the switch beam supporting structure 6 are the same as those in the prior art, and are not described herein again.

Based on the same inventive concept, the embodiment of the present application provides a method for manufacturing a mems switch, as shown in fig. 11, the method comprising:

s101, providing a substrate 3, and preparing a signal wire 2 on the substrate 3;

s102, preparing a conductive part 9 on one side of the signal wire 2 far away from the substrate 3;

and S103, preparing a switch beam 10 on one side of the conducting part 9 far away from the substrate 3, wherein the switch beam 10 is provided with a containing hole 8, the orthographic projection of the containing hole 8 on the substrate 3 is positioned in the orthographic projection of the signal wire 2 on the substrate 3, and the orthographic projection of the conducting part 9 on the substrate 3 is positioned in the orthographic projection of the containing hole 8 on the substrate 3.

The MEMS switch is prepared by the above method. When the MEMS switch is in an on state, a gap is formed between the switch beam 10 and the signal line 2, and an on-state capacitor is formed between the switch beam 10 and the signal line 2; when the mems switch is in the off state, since the orthographic projection of the conductive part 9 on the substrate 3 is located in the orthographic projection of the receiving hole 8 on the substrate 3, and the conductive part 9 passes through the receiving hole 8, a first off-state capacitor is formed between the switch beam 10 and the signal line 2, and a second off-state capacitor is formed between the conductive part 9 and the switch beam 10. The second off-state capacitor is introduced by arranging the conductive part 9 and the containing hole 8, so that the off-state capacitor is effectively increased, the capacitance ratio of the off-state capacitor to the on-state capacitor can be effectively improved, and the radio frequency performance of the micro electromechanical system switch is further improved.

Optionally, in this embodiment of the present application, before the signal line 2 is fabricated on the substrate 3, the fabrication method further includes: preparing an insulating layer 7 on the substrate 3; the above-described preparation of the signal line 2 on the substrate 3 includes: two ground wires 1 are prepared on two sides of a signal wire 2, the signal wire 2 is positioned between the two ground wires 1, and the signal wire 2 is separated and insulated from the ground wires 1.

As shown in fig. 12, in the embodiment of the present invention, when the method is implemented, a gold film layer is deposited or electroplated on the substrate 3, and then the gold film layer is patterned through a patterning process to form the signal line 2 and the ground line 1. Optionally, the gold film layer is patterned by wet etching.

Optionally, in this embodiment, preparing the conductive portion 9 on the side of the signal line 2 away from the substrate 3 includes: manufacturing a dielectric layer 4 on one side of the signal line 2, which is far away from the substrate 3, through a composition process, wherein the dielectric layer 4 is provided with a through hole so as to expose the signal line 2; and manufacturing a conductive part 9 on one side of the dielectric layer 4 far away from the substrate 3 through a patterning process, wherein the conductive part 9 is filled in the through hole, and part of the conductive part 9 protrudes out of the dielectric layer 4.

In the embodiment of the present invention, during specific implementation, siNX is deposited on a side of the signal line 2 away from the substrate 3 by Plasma Enhanced Chemical Vapor Deposition (PECVD), and is patterned by Reactive Ion Etching (RIE) technology to form the dielectric layer 4, wherein a through hole (as shown in fig. 13) needs to be formed in the center of the dielectric layer 4 to deposit the conductive portion 9. Then, a gold film is deposited on the side of the dielectric layer 4 away from the substrate 3, and the deposited gold film is filled in the via hole of the dielectric layer 4, and then the gold film is patterned by a patterning process to form the conductive portion 9 (as shown in fig. 14).

The conductive portion 9, the dielectric layer 4, and the through-hole are prepared by the above-described method. The through hole is used for avoiding the conductive part 9, so that one end of the conductive part 9 is conveniently connected with the signal line 2, and the other end of the conductive part 9 can protrude out of the dielectric layer 4, so that when the micro-electromechanical system switch is in an off state, a second off-state capacitor can be formed between the conductive part 9 and the switch beam 10.

Alternatively, in the embodiment of the present application, preparing the switch beam 10 on the side of the conductive portion 9 away from the substrate 3 includes: preparing a sacrificial layer 11 on one side of the conductive part 9 far away from the substrate 3, wherein the sacrificial layer 11 covers the conductive part 9, the signal line 2 and the partial ground line 1 (namely, the partial ground line 1 is exposed and not covered by the sacrificial layer 11); manufacturing a conducting layer on one side of the sacrificial layer 11, which is far away from the substrate 3, by a composition process, wherein the conducting layer covers the sacrificial layer 11 and is connected with the two ground wires 1; the conductive layer is subjected to a patterning process to form a receiving hole, and the sacrificial layer 11 is removed to form the switch beam 10.

In the embodiment of the present application, in specific implementation, a polyimide film layer is first spin-coated on a side of the conductive portion 9 away from the substrate 3, and the polyimide film layer is patterned by RIE to form a sacrificial layer 11, where the sacrificial layer 11 covers the conductive portion 9, the signal line 2, and a part of the ground line 1 (as shown in fig. 15); then, depositing a gold film layer on the sacrificial layer 11, and performing patterning processing on the gold film layer through a patterning process to form a conductive layer (as shown in fig. 16); then, the conducting layer is subjected to patterning treatment through a patterning process to form accommodating holes (as shown in FIG. 17); finally, the sacrificial layer 11 is removed to form the switch beam 10 (as shown in fig. 18).

In the embodiment of the present application, the substrate 3 is made of silicon, the signal line 2, the ground line 1 and the switch beam 10 are made of gold, the sacrificial layer is made of polyimide, and the dielectric layer 4 is made of SiNx (silicon nitride). In practical applications, the material of the substrate is not limited to these materials, and may also be glass, sapphire, silicon carbide, si (silicon), gaAs (gallium arsenide), etc., the material of the signal line 2, the ground line 1, and the switch beam 10 may also be any one of copper, iron, silver, gold, aluminum, nickel, or any combination thereof, etc., and the material of the sacrificial layer may also be photoresist, BPSG (borophosphosilicate glass), etc.

It should be noted that the above-mentioned patterning process includes a part or all of processes of coating, exposing, developing, etching and removing the photoresist.

By applying the embodiment of the application, at least the following beneficial effects can be realized:

when the MEMS switch is in an on state, an on-state capacitor is formed between the switch beam and the signal line; when the MEMS switch is in an off state, a first off-state capacitor is formed between the switch beam and the signal line, and a second off-state capacitor is formed between the conductive part and the switch beam. In the embodiment of the application, one or more pairs of second off-state capacitors are introduced between the switch beam and the signal line, so that the off-state capacitors can be effectively increased without almost influencing the on-state capacitors, the capacitance ratio of the off-state capacitors to the on-state capacitors of the MEMS switch can be effectively increased, and the radio frequency performance of the MEMS switch is further improved. The embodiment of the application has almost no influence on the driving voltage because the distance between the switch beam body and the dielectric layer is not increased, dielectric breakdown is not easy to cause because the thickness of the dielectric layer is not reduced, and the switch beam is simple in process and easy to manufacture.

The MEMS switch in the embodiment of the application can be applied to the design of a radio frequency switch, in particular to the design of a MEMS radio frequency switch with a high capacitance ratio.

Those of skill in the art will understand that various operations, methods, steps in the flow, measures, schemes discussed in this application can be alternated, modified, combined, or deleted. Further, other steps, measures, or schemes in various operations, methods, or flows that have been discussed in this application can be alternated, altered, rearranged, broken down, combined, or deleted. Further, steps, measures, schemes in the prior art having various operations, methods, procedures disclosed in the present application may also be alternated, modified, rearranged, decomposed, combined, or deleted.

In the description of the present application, the directions or positional relationships indicated by the words "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like are for convenience of description or simplicity of describing the embodiments of the present application based on the exemplary directions or positional relationships shown in the drawings, and do not indicate or imply that the devices or components referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, are not to be construed as limiting the present application.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

In the description herein, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

It should be understood that, although the steps in the flowcharts of the figures are shown in sequence as indicated by the arrows, the order of execution of the steps is not limited to the order indicated by the arrows. In some implementations of the embodiments of the present application, the steps in the various flows may be performed in other sequences as desired, unless explicitly stated otherwise herein. Moreover, some or all of the steps in each flowchart may include multiple sub-steps or multiple stages, depending on the actual implementation scenario. Some or all of the sub-steps or phases may be executed at the same time, or may be executed at different times in a scenario where the execution time is different, and the execution order of the sub-steps or phases may be flexibly configured according to the requirement, which is not limited in this embodiment of the application.

The foregoing is only a part of the embodiments of the present application, and it should be noted that it is within the scope of the embodiments of the present application that other similar implementation means based on the technical idea of the present application can be adopted by those skilled in the art without departing from the technical idea of the present application.

Claims

1. A micro-electromechanical system switch, comprising:

a substrate;

a signal line provided on one side of the substrate;

the switch beam is positioned on one side, far away from the substrate, of the signal line, and provided with a containing hole, and the orthographic projection of the containing hole on the substrate is positioned in the orthographic projection of the signal line on the substrate;

and the conductive part is connected with the signal wire and positioned between the signal wire and the switch beam, and the orthographic projection of the conductive part on the substrate is positioned in the orthographic projection of the accommodating hole on the substrate.

2. The MEMS switch of claim 1,

the number of the conductive parts and the accommodating holes is one; alternatively, the first and second electrodes may be,

the number of the conducting parts and the accommodating holes is at least two, the conducting parts and the accommodating holes are arranged in a one-to-one correspondence mode, the conducting parts are arranged in an array mode, and the accommodating holes are arranged in an array mode.

3. The MEMS switch of claim 1,

the cross section of the conductive part is circular or polygonal; and/or the presence of a gas in the atmosphere,

the cross section shape of the containing hole is the same as that of the conductive part;

wherein the cross-section is parallel to the substrate.

4. The mems switch of claim 1, further comprising a dielectric layer on one side of the substrate and covering at least a portion of the signal line;

the dielectric layer is provided with a through hole, one end of the conductive part is connected with the signal line, and the other end of the conductive part penetrates out of the through hole and protrudes out of the dielectric layer.

5. The mems switch of claim 1, further comprising a dielectric layer on one side of the substrate and covering a portion of the signal line;

the dielectric layer is provided with a contact hole, the conductive part is arranged in the contact hole, one end of the conductive part is connected with the signal line, and the other end of the conductive part is flush with the outer surface of one side of the dielectric layer, which is far away from the substrate, or lower than the outer surface of one side of the dielectric layer, which is far away from the substrate;

and the size of the accommodating hole is larger than the sum of the sizes of the conductive part and the dielectric layer along the direction parallel to the substrate.

6. The MEMS switch of any one of claims 1 to 5,

the ground wire is positioned on one side of the signal wire, and the ground wire and the signal wire are arranged at intervals in an insulating manner; one end of the switch beam is connected with the ground wire; and/or the presence of a gas in the gas,

further comprising an insulating layer disposed between the substrate and the signal line.

7. A method of making a microelectromechanical system switch, comprising:

providing a substrate, and preparing a signal wire on the substrate;

preparing a conductive part on one side of the signal wire far away from the substrate;

preparing a switch beam on one side of the conductive part, which is far away from the substrate, wherein the switch beam is provided with an accommodating hole, the orthographic projection of the accommodating hole on the substrate is positioned in the orthographic projection of the signal line on the substrate, and the orthographic projection of the conductive part on the substrate is positioned in the orthographic projection of the accommodating hole on the substrate.

8. The method of making a MEMS switch of claim 7,

before the signal line is prepared on the substrate, the method further comprises the following steps: preparing an insulating layer on the substrate;

the preparing of the signal line on the substrate includes:

two ground wires are prepared on two sides of the signal wire, the signal wire is positioned between the two ground wires, and the signal wire and the ground wires are separated and insulated.

9. The method of making a MEMS switch of claim 8,

the preparation of the conductive part on one side of the signal wire far away from the substrate comprises the following steps:

manufacturing a dielectric layer on one side of the signal line, which is far away from the substrate, through a composition process, wherein the dielectric layer is provided with a through hole so as to expose the signal line;

and manufacturing a conductive part on one side of the dielectric layer far away from the substrate by a composition process, wherein the conductive part is filled in the through hole, and part of the conductive part protrudes out of the dielectric layer.

10. The method of fabricating a mems switch as claimed in claim 9, wherein said fabricating a switch beam on a side of said conductive portion remote from said substrate comprises:

preparing a sacrificial layer on one side of the conductive part far away from the substrate, wherein the sacrificial layer covers the conductive part, the signal line and part of the ground line;

manufacturing a conducting layer on one side, far away from the substrate, of the sacrificial layer through a composition process, wherein the conducting layer covers the sacrificial layer and is connected with the two ground wires;

and carrying out a composition process on the conductive layer to form the containing hole, and removing the sacrificial layer to form the switch beam.