Micro electro mechanical system switch and method for manufacturing micro electro mechanical system switch

Abstract

The embodiment of the present application provides a micro electro mechanical system switch and a preparation method of the micro electro mechanical system switch. The micro electro mechanical system switch comprises a substrate, a signal line arranged on one side of the substrate, a switch beam located on the side, away from the substrate, of the signal line, the switch beam being provided with a containing hole, the orthographic projection of the containing hole on the substrate being located in the orthographic projection of the signal line on the substrate, and a conductive part connected with the signal line and located between the signal line and the switch beam, the orthographic projection of the conductive part on the substrate being located in the orthographic projection of the containing hole on the substrate. The embodiment of the present application can effectively improve the capacitance ratio of the off-state capacitance and the on-state capacitance, thereby improving the radio frequency performance of the micro electro mechanical system switch.

Description

Technical Field

[0001] This application relates to the field of microelectromechanical systems (MEMS) technology, and more specifically, to a microelectromechanical system switch and a method for manufacturing the microelectromechanical system switch. Background Technology

[0002] Compared with traditional switches, microelectromechanical systems (MEMS) have advantages such as low loss, low power consumption, good linearity, high isolation, small size and easy integration. They avoid the ohmic losses and IV nonlinearity problems caused by PN junctions and metal-semiconductor junctions of traditional field-effect transistors (FETs) and pin switches. They also overcome the large size, high power consumption and parasitic effects caused by component interconnections of traditional external discrete components. They can replace traditional semiconductor devices in microwave systems.

[0003] The insertion loss and isolation of a MEMS switch are related to the ratio of its coupling capacitance when the switch is on and off. To reduce the insertion loss when the switch is on, the coupling capacitance Con (on-state capacitance) of the MEMS switch in the on-state should be as small as possible; conversely, to improve the isolation when the MEMS switch is off, the coupling capacitance Coff (off-state capacitance) should be as large as possible. Therefore, the larger the capacitance ratio Coff / Con of a MEMS switch, the better its RF performance.

[0004] Therefore, there is a need to provide a microelectromechanical system switch that can effectively improve the capacitance ratio Coff / Con, thereby improving the radio frequency performance of the microelectromechanical system switch. Summary of the Invention

[0005] This application addresses the shortcomings of existing methods by proposing a microelectromechanical system switch and a method for fabricating the microelectromechanical system switch, which can effectively improve the capacitance ratio and thus enhance the radio frequency performance of the microelectromechanical system switch.

[0006] In a first aspect, embodiments of this application provide a microelectromechanical system switch, comprising: a substrate; a signal line disposed on one side of the substrate; a switch beam located on the side of the signal line away from the substrate, the switch beam having a receiving hole, the orthographic projection of the receiving hole on the substrate being located within the orthographic projection of the signal line on the substrate; and a conductive part connected to the signal line and located between the signal line and the switch beam, the orthographic projection of the conductive part on the substrate being located within the orthographic projection of the receiving hole on the substrate.

[0007] Optionally, the number of conductive parts and receiving holes is one; or, the number of conductive parts and receiving holes is at least two, with each conductive part and receiving hole corresponding to the other, and at least two conductive parts arranged in an array and at least two receiving holes arranged in an array.

[0008] Optionally, the cross-section of the conductive part is circular or polygonal; and / or, the cross-sectional shape of the receiving hole is the same as the cross-sectional shape of the conductive part; wherein the cross-section is parallel to the substrate.

[0009] Optionally, it also includes a dielectric layer located on one side of the substrate and covering at least a portion of the signal line; the dielectric layer has a via, one end of the conductive portion is connected to the signal line, and the other end extends through the via and protrudes from the dielectric layer.

[0010] Optionally, it also includes a dielectric layer located on one side of the substrate and covering part of the signal line; the dielectric layer has a contact hole, a conductive part is disposed in the contact hole, one end of the conductive part is connected to the signal line, and the other end is flush with or lower than the outer surface of the dielectric layer on the side away from the substrate; along the direction parallel to the substrate, the size of the receiving hole is greater than the sum of the sizes of the conductive part and the dielectric layer.

[0011] Optionally, it also includes a ground wire located on one side of the signal line, the ground wire being spaced apart from and insulated from the signal line; one end of the switch beam being connected to the ground wire; and / or, it also includes an insulating layer disposed between the substrate and the signal line.

[0012] Secondly, embodiments of this application provide a method for fabricating a microelectromechanical system switch, comprising: providing a substrate and fabricating a signal line on the substrate; fabricating a conductive portion on the side of the signal line away from the substrate; fabricating a switch beam on the side of the conductive portion away from the substrate, the switch beam having a receiving hole, the orthographic projection of the receiving hole on the substrate being located within the orthographic projection of the signal line on the substrate, and the orthographic projection of the conductive portion on the substrate being located within the orthographic projection of the receiving hole on the substrate.

[0013] Optionally, before fabricating the signal line on the substrate, the method further includes: fabricating an insulating layer on the substrate; and fabricating the signal line on the substrate, including: fabricating two ground lines on both sides of the signal line, with the signal line located between the two ground lines, and the signal line being spaced apart from and insulated from the ground lines.

[0014] Optionally, a conductive portion is fabricated on the side of the signal line away from the substrate, including: fabricating a dielectric layer on the side of the signal line away from the substrate by a patterning process, wherein the dielectric layer has vias to expose the signal line; and fabricating a conductive portion on the side of the dielectric layer away from the substrate by a patterning process, wherein the conductive portion fills the vias and a portion of the conductive portion protrudes from the dielectric layer.

[0015] Optionally, a switch beam is fabricated on the side of the conductive portion away from the substrate, comprising: fabricating a sacrificial layer on the side of the conductive portion away from the substrate, the sacrificial layer covering the conductive portion, signal lines, and a portion of ground lines; fabricating a conductive layer on the side of the sacrificial layer away from the substrate by a patterning process, the conductive layer covering the sacrificial layer, and the conductive layer being connected to both ground lines; performing a patterning process on the conductive layer to form accommodating vias, and removing the sacrificial layer to form a switch beam.

[0016] The beneficial technical effects of the technical solutions provided in this application include:

[0017] The microelectromechanical system (MEMS) switch provided in this application provides an on-state capacitor. When the switch is in the on state, a gap exists between the switch beam and the conductive part. The conductive part is connected to the signal line and located between the signal line and the switch beam, thus creating an on-state capacitor between them. When the switch is in the off state, the orthogonal projection of the conductive part onto the substrate lies within the orthogonal projection of the accommodating hole onto the substrate. The conductive part passes through the accommodating hole. Therefore, 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. This application introduces a second off-state capacitor by providing the conductive part and the accommodating hole, effectively increasing the off-state capacitor and thus improving the capacitance ratio between the off-state and on-state capacitors, thereby enhancing the radio frequency performance of the MEMS switch.

[0018] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 This is a schematic diagram of a typical capacitive MEMS switch.

[0021] Figure 2 This is the equivalent circuit diagram of a typical capacitive MEMS switch;

[0022] Figure 3 A schematic diagram of a microelectromechanical system switch provided in an embodiment of this application;

[0023] Figure 4 An equivalent circuit diagram of a microelectromechanical system switch in the on state is provided for an embodiment of this application;

[0024] Figure 5 An equivalent circuit diagram of a microelectromechanical system switch in the off state is provided for an embodiment of this application;

[0025] Figure 6 A cross-sectional view of a microelectromechanical system switch in the open state provided in an embodiment of this application;

[0026] Figure 7 A cross-sectional view of a microelectromechanical system switch in the off state provided in an embodiment of this application;

[0027] Figure 8 This is a schematic diagram of the structure of a second off-state capacitor of a microelectromechanical system switch in the off state, provided in an embodiment of this application.

[0028] Figure 9 A schematic diagram of a microelectromechanical system switch provided in another embodiment of this application;

[0029] Figure 10 A schematic diagram of the structure of a microelectromechanical system switch provided in another embodiment of this application;

[0030] Figure 11 A flowchart illustrating a method for fabricating a microelectromechanical system switch provided in this application embodiment;

[0031] Figures 12 to 18 This is a schematic diagram of the structure of a microelectromechanical system switch fabrication method provided in this application embodiment at different stages.

[0032] Figure label:

[0033] 1-Ground; 2-Signal line; 3-Substrate; 4-Dielectric layer; 5-Switch beam body; 6-Switch beam support structure; 7-Insulating layer; 8-Accommodation hole; 9-Conductive part; 10-Switch beam; 11-Sacrificial layer. Detailed Implementation

[0034] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0035] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude implementations of other features, information, data, steps, operations, elements, components, and / or combinations thereof supported by this art. It should be understood that when we say an element is “connected” or “coupled” to another element, the element may be directly connected or coupled to the other element, or it may mean that the element and the other element are connected through an intermediate element. Furthermore, “connected” or “coupled” as used herein may include wireless connection or wireless coupling. The term “and / or” as used herein means at least one of the items defined by the term; for example, “A and / or B” may be implemented as “A,” or as “B,” or as “A and B.”

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0037] Radio frequency (RF) switches connect any one or more of multiple RF signals through control logic to achieve switching between different models, including switching between receiving and transmitting, and switching between different frequency bands, in order to achieve the purpose of sharing antennas and saving terminal product costs.

[0038] Compared with traditional switches, microelectromechanical system (MEMS) switches have advantages such as low loss, low power consumption, good linearity, high isolation, small size, and easy integration. They avoid the ohmic losses and IV (current-voltage curve) nonlinearity problems caused by PN junctions and metal-semiconductor junctions in traditional field-effect transistors (FETs) and pin switches. They also overcome the large size, high power consumption, and parasitic effects caused by component interconnections of traditional external discrete components. They can replace traditional semiconductor devices in microwave systems, such as radio frequency (RF) MEMS phase shifters, RF MEMS smart antennas, T / R (transmitter and receiver) modules, radar early warning, tactical and strategic reconnaissance, satellite networking, and guidance in military fields. They can also be applied to mobile devices such as mobile phones, consumer electronics, and navigation systems in civilian fields.

[0039] The insertion loss and isolation of a MEMS switch are related to the ratio of its coupling capacitance when the switch is on and off. To reduce the insertion loss when the switch is on, the coupling capacitance Con (on-state capacitance) of the MEMS switch in the on-state should be as small as possible; while to improve the isolation when the MEMS switch is off, the coupling capacitance Coff (off-state capacitance) of the MEMS switch should be as large as possible. Therefore, the larger the capacitance ratio Coff / Con of a MEMS switch, the better its RF performance.

[0040] Figure 1 This is a schematic diagram of a typical capacitive MEMS switch. 1 is the ground wire, 2 is the signal wire, 3 is the substrate, 4 is the dielectric layer, 5 is the switch beam body, 6 is the switch beam support structure, and 7 is the insulating layer. The switch beam body 5 and the switch beam support structure 6 together constitute the switch beam. Ground wire 1, signal wire 2, substrate 3, and insulating layer 7 together form a coplanar waveguide (CPW). Radio frequency signals can propagate through the coplanar waveguide. The switch beam body 5 is connected to the two ground wires 1 located on both sides of the signal wire 2 via the switch beam support structure 6. Applying a driving voltage between the signal wire 2 and the ground wire 1 enables switching action. When the driving voltage is applied, the switch beam body 5 moves downwards under the influence of electrostatic force. When the switch beam body 5 contacts the dielectric layer 4, the signal is interrupted. When the driving voltage is removed, the switch beam body 5 returns to its initial position (i.e., Figure 1 (The position of the switch beam body 5) enables the signal to be turned on.

[0041] In a typical capacitive MEMS switch, the switch beam body 5 and the signal line 2 are equivalent to a parallel plate capacitor, and the capacitance between the switch beam body 5 and the signal line 2 is equivalent to a parallel plate capacitor. In the open state, the dielectric in the capacitor is air and dielectric layer 4, and in the closed state, the dielectric in the capacitor is dielectric layer 4. Figure 2 This is the equivalent circuit diagram of a typical capacitive MEMS switch, where Z0 is the input and output impedance of the CPW, Con is the open-state capacitance between the switch beam body 5 and the signal line 2 when no driving voltage is applied, and Coff is the closed-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.

[0042] The typical off-state capacitance Coff and on-state capacitance Con of a capacitive MEMS switch are as follows:

[0043]

[0044] Where ε0 is the vacuum permittivity, εr is the relative permittivity of the dielectric layer, d is the thickness of the dielectric layer, g is the distance between the dielectric layer and the switch beam body, and S0 is the projected overlap area of ​​the switch beam body, the dielectric layer, and the signal line.

[0045] The capacitance ratio of a typical capacitive MEMS switch for:

[0046] As can be seen from the above formula, the capacitance ratio can be increased by increasing the distance g between the dielectric layer and the switch beam body, increasing the relative permittivity εr of the dielectric layer, and decreasing the thickness d of the dielectric layer. However, these methods will introduce other problems. For example, increasing the distance between the switch beam body and the dielectric layer will inevitably increase the driving voltage, and decreasing the thickness of the dielectric layer will make the dielectric layer more prone to dielectric breakdown.

[0047] To address the aforementioned issues, this application and its embodiments provide a microelectromechanical system switch and a method for fabricating the microelectromechanical system switch. This microelectromechanical system switch can effectively improve the capacitance ratio, thereby enhancing its radio frequency performance.

[0048] It should be noted that, in this application, the capacitance ratio of the MEMS switch refers to the ratio of the off-state capacitance (Coff) to the on-state capacitance (Con) of the MEMS switch.

[0049] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, borrowed, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0050] This application provides a microelectromechanical system switch, and a schematic diagram of the microelectromechanical system switch is shown below. Figure 3 , Figures 6 to 8 As shown, the system includes a substrate 3, a signal line 2, a switch beam 10, and a conductive part 9. The signal line 2 is disposed on one side of the substrate 3. The switch beam 10 is located on the side of the signal line 2 away from the substrate 3, and the switch beam 10 has a receiving hole 8. The orthographic projection of the receiving hole 8 on the substrate 3 lies within the orthographic projection of the signal line 2 on the substrate 3. The conductive part 9 is connected to the signal line 2 and is located between the signal line 2 and the switch beam 10. The orthographic projection of the conductive part 9 on the substrate 3 lies within the orthographic projection of the receiving hole 8 on the substrate 3. When the microelectromechanical system switch is in the open state, there is a gap between the switch beam 10 and the conductive part 9 (e.g., ...). Figure 6 (as shown); when the microelectromechanical system switch is in the off state, the conductive part 9 passes through the receiving hole 8 (as shown). Figure 7 (As shown).

[0051] Specifically, the specific arrangement of the substrate 3 and the signal line 2 in the embodiments of this application is the same as that in the prior art, and will not be repeated here.

[0052] In the above configuration, the substrate 3 supports the signal line 2, the switch beam 10, and the conductive part 9. When the microelectromechanical system switch is in the on state, since there is a gap between the switch beam 10 and the conductive part 9, and the conductive part 9 is connected to the signal line 2 and located between the signal line 2 and the switch beam 10, there is also a gap between the switch beam 10 and the signal line 2, forming an on-state capacitance between the switch beam 10 and the signal line 2. When the microelectromechanical system switch is in the off state, since the orthographic projection of the conductive part 9 on the substrate 3 is located within the orthographic projection of the accommodating hole 8 on the substrate 3, and the conductive part 9 passes through the accommodating hole 8, a first off-state capacitance is formed between the switch beam 10 and the signal line 2, and a second off-state capacitance is formed between the conductive part 9 and the switch beam 10. Compared to a typical capacitive MEMS switch, this embodiment introduces a second off-state capacitance by setting the conductive part 9 and the accommodating hole 8, effectively increasing the off-state capacitance, thereby effectively improving the capacitance ratio between the off-state capacitance and the on-state capacitance, and thus improving the radio frequency performance of the microelectromechanical system switch.

[0053] Optionally, such as Figure 3 , Figures 6 to 8 As shown in the embodiment of this application, the number of conductive part 9 and receiving hole 8 is one each; this setting makes the process simple and easy to manufacture.

[0054] Of course, in optional embodiments of this application, the number of conductive parts and receiving holes can also be at least two, depending on actual needs, with each conductive part and receiving hole corresponding to another, and at least two conductive parts arranged in an array, and at least two receiving holes arranged in an array (e.g. Figure 10 (As shown).

[0055] Optionally, such as Figure 3 and Figure 8 As shown in the embodiment of this application, the cross-section of the conductive part 9 is circular; this configuration simplifies the process and makes it easy to manufacture.

[0056] Optionally, in this embodiment, the conductive part 9 has a cylindrical structure, and the receiving hole 8 has a cylindrical hole. Of course, in an optional embodiment of this application, the conductive part 9 can also be a frustum-shaped structure, and correspondingly, the receiving hole 8 can be a frustum-shaped hole, depending on actual needs.

[0057] Optionally, such as Figure 3 As shown in the embodiment of this application, the cross-sectional shape of the receiving hole 8 is the same as the cross-sectional shape of the conductive part 9; this arrangement facilitates the conductive part 9 to pass through the receiving hole 8. The cross-section of the receiving hole 8 is circular.

[0058] It should be noted that the cross-section described above is parallel to the substrate.

[0059] Of course, in optional embodiments of this application, the cross-section of the conductive part can be polygonal (e.g., rectangular) or other shapes according to actual needs, and the cross-sectional shape of the receiving hole can be adaptively adjusted according to the cross-sectional shape of the conductive part (e.g., ...). Figure 9 (As shown).

[0060] Optionally, such as Figures 6 to 8 As shown in the embodiment of this application, the receiving hole 8 is a through hole; this setting makes the process simple and easy to manufacture; at the same time, the receiving hole 8 penetrates through the switch beam 10, and when the conductive part 9 passes through the receiving hole 8, the corresponding area between the conductive part 9 and the switch beam 10 is the largest, which can maximize the capacitance between the conductive part 9 and the switch beam 10. This setting helps to increase the off-state capacitance.

[0061] This application proposes a design scheme to improve the capacitance ratio of MEMS switches. One or more pairs of cylindrical capacitors are introduced between the switch beam 10 and the signal line 2, which effectively increases the off-state capacitance while having almost no effect on the on-state capacitance, thereby effectively increasing the capacitance ratio Coff / Con of the MEMS switch. Compared with traditional methods for improving the capacitance ratio of MEMS switches, this embodiment has almost no effect on the driving voltage (i.e., no increase in driving voltage) because it does not increase the distance between the switch beam body and the dielectric layer. Since it does not reduce the dielectric layer thickness, it is less prone to dielectric breakdown, and the process is simple and easy to manufacture.

[0062] When a driving voltage is applied to the switch beam 10 and the signal line 2, the switch beam 10 moves downward under electrostatic force. The off-state capacitance Coff is formed by the parallel connection of the plate capacitor between the switch beam 10 and the signal line 2 and the cylindrical capacitor between the switch beam 10 and the conductive part 9. Therefore, the off-state capacitance Coff will increase, while the effect on the on-state capacitance is small, thereby increasing the capacitance ratio Coff / Con. Figure 4 This is an equivalent circuit diagram of the MEMS switch in the on state in the embodiments of this application. Figure 5 This is the equivalent circuit diagram of the MEMS switch in the off state in the embodiments of this application.

[0063] In this embodiment of the application, the on-state capacitance Con of the MEMS switch satisfies the following relationship: The capacitance Cp of the first off-state capacitor Coff1 of the MEMS switch satisfies the following relationship: The capacitance Cc of the second off-state capacitor Coff2 of the MEMS switch satisfies the following relationship: In this embodiment of the application, taking an example where both the conductive part 9 and the accommodating hole 8 are one, the off-state capacitance Coff of the MEMS switch satisfies the following relationship: The capacitance ratio Coff / Con of a MEMS switch satisfies the following relationship:

[0064] Wherein, Con is the on-state capacitance, Coff is the off-state capacitance, Cp is the capacitance of the first off-state capacitor, Cc is the capacitance of the second off-state capacitor, ε0 is the vacuum dielectric constant, S0 is the projected overlapping area of ​​the switch beam, dielectric layer and signal line, g is the distance between the dielectric layer and the switch beam, d is the thickness of the dielectric layer, εr is the relative dielectric constant of the dielectric layer, dbeam is the thickness of the switch beam, ra is the radius of the accommodating hole, and rb is the radius of the conductive part.

[0065] As can be seen from the above formula, compared to a typical capacitive MEMS switch, the capacitance ratio of the MEMS switch in this embodiment increases.

[0066] Optionally, such as Figure 3 , Figure 6 and Figure 7 As shown, the microelectromechanical system switch of this application embodiment further includes a dielectric layer 4, which is located on one side of the substrate 3 and covers at least a portion of the signal line 2; the dielectric layer 4 is provided with a through hole, one end of the conductive part 9 is connected to the signal line 2, and the other end passes through the through hole and protrudes from the dielectric layer 4.

[0067] Specifically, apart from the through-hole provided in the dielectric layer 4, the specific arrangement of the rest of the structure of the dielectric layer 4 is the same as that in the prior art, and will not be repeated here.

[0068] In the above configuration, the through hole is used to avoid the conductive part 9, facilitating the connection of one end of the conductive part 9 to the signal line 2, while allowing the other end of the conductive part 9 to protrude from the dielectric layer 4. This allows a second off-state capacitor to be formed between the conductive part 9 and the switch beam 10 when the microelectromechanical system switch is in the off state. When the microelectromechanical system switch is in the off state, the conductive part 9 passes through the receiving hole 8, and the dielectric of the second off-state capacitor is air.

[0069] Of course, in another embodiment of this application, the microelectromechanical system switch may also include a dielectric layer 4, which is located on one side of the substrate 3 and covers part of the signal line 2, according to actual needs. The dielectric layer 4 is provided with a contact hole, and a conductive part 9 is disposed in the contact hole. One end of the conductive part 9 is connected to the signal line 2, and the other end is flush with or lower than the outer surface of the dielectric layer 4 on the side away from the substrate 3. Along the direction parallel to the substrate 3, the size of the receiving hole 8 is greater than the sum of the sizes of the conductive part 9 and the dielectric layer 4. At this time, since the size of the receiving hole 8 is greater than the sum of the sizes of the conductive part 9 and the dielectric layer 4, when the microelectromechanical system switch is in the off state, the conductive part 9 and part of the dielectric layer 4 are located in the receiving hole 8. At this time, the dielectric of the second off-state capacitor formed by the conductive part 9 and the switch beam 10 is air and the dielectric layer 4. The increased dielectric of the second off-state capacitor can increase the capacitance of the second off-state capacitor, effectively increasing the off-state capacitance, thereby effectively increasing the capacitance ratio of the off-state capacitor to the on-state capacitor, and thus improving the radio frequency performance of the microelectromechanical system switch.

[0070] It should be noted that if the dielectric layer 4 completely covers 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, on the one hand, a capacitor cannot be formed between the signal line 2 and the switch beam 10, and applying a driving voltage to the signal line 2 will not make the switch beam 10 move closer to the signal line 2, thus making it impossible to put the MEMS switch in the off state. On the other hand, the dielectric layer 4 will prevent the switch beam 10 from moving closer to the signal line 2, making it difficult for the switch beam 10 and the conductive part 9 to cooperate in forming a second off-state capacitor. Therefore, in another embodiment of the present application, the dielectric layer 4 only covers a portion of the signal line 2. Along the direction parallel to the substrate 3, 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. In this case, the switch beam 10 can cooperate with the signal line 2 to form a capacitor. When a driving voltage is applied to the signal line 2, the switch beam 10 can move closer to the signal line 2 under the action of electrostatic force. At the same time, it can be ensured that when the microelectromechanical system switch is in the off state, the conductive part 9 and a portion of the dielectric layer 4 are both located in the accommodating hole 8, thereby increasing the dielectric of the second off-state capacitor and improving the capacitance of the second off-state capacitor.

[0071] In another embodiment of this application, the size of the dielectric layer 4 is smaller than the size of the signal line 2 along the direction parallel to the substrate 3. The above arrangement can achieve the purpose of making the dielectric layer 4 cover only part of the signal line 2.

[0072] It should be noted that in the actual production process, the sides of signal line 2 and dielectric layer 4 will have a slope (for example, in some optional embodiments, theoretically the longitudinal section of signal line 2 is rectangular, but the longitudinal section of the signal line obtained in actual production is trapezoidal, where the longitudinal section is perpendicular to the substrate). Depending on the actual production process, the slope angle of the sides of signal line 2 and dielectric layer 4 will be different. For example, when signal line 2 or dielectric layer 4 is formed by wet etching, the slope angle of the sides of signal line 2 or dielectric layer 4 is about 45°. When signal line 2 or dielectric layer 4 is formed by dry etching, the slope angle of the sides of signal line 2 or dielectric layer 4 may reach 60° to 70°. If the lift-off process (i.e., peel-off process) is used, the slope angle may be even larger.

[0073] Optionally, such as Figure 3 , Figure 6 and Figure 7 As shown, the microelectromechanical system switch of this application embodiment also includes a ground wire 1, which is located on one side of the signal line 2. The ground wire 1 is spaced apart from and insulated from the signal line 2; one end of the switch beam 10 is connected to the ground wire 1.

[0074] Optionally, such as Figure 3 , Figure 6 and Figure 7 As shown, the microelectromechanical system switch of this embodiment further includes an insulating layer 7, which is disposed between the substrate 3 and the signal line 2. The insulating layer 7 is also disposed between the substrate 3 and the ground line 1.

[0075] Specifically, the specific arrangement of ground line 1, signal line 2, substrate 3 and insulating layer 7 is the same as that in the prior art, and will not be repeated here.

[0076] Optionally, in this embodiment, the switch beam 10 is elastic; the switch beam 10 includes a connected switch beam body 5 and a switch beam support structure 6, with the switch beam body 5 bridging two ground wires 1 located on both sides of the signal line 2 via the switch beam support structure 6. When a driving voltage is applied, under the action of electrostatic force, the switch beam body 5 can move from its initial position (at which time the MEMS switch is in the on state) toward the signal line 2; when the driving voltage is stopped, under the action of its own elasticity, the switch beam body 5 can return to its initial position. Optionally, the switch beam body 5 and the switch beam support structure 6 are integrally formed.

[0077] Specifically, in this embodiment, except that the switch beam body 5 is provided with a receiving hole 8, the other structures of the switch beam body 5 and the specific arrangement of the switch beam support structure 6 are the same as those in the prior art, and will not be described again here.

[0078] Based on the same inventive concept, embodiments of this application provide a method for fabricating a microelectromechanical system switch, such as... Figure 11As shown, the preparation method includes:

[0079] S101. Provide a substrate 3 and fabricate signal lines 2 on the substrate 3;

[0080] S102. A conductive portion 9 is prepared on the side of the signal line 2 away from the substrate 3;

[0081] S103. A switch beam 10 is prepared on the side of the conductive part 9 away from the substrate 3. The switch beam 10 is provided with a receiving hole 8. The orthographic projection of the receiving hole 8 on the substrate 3 is located within the orthographic projection of the signal line 2 on the substrate 3. The orthographic projection of the conductive part 9 on the substrate 3 is located within the orthographic projection of the receiving hole 8 on the substrate 3.

[0082] A microelectromechanical system (MEMS) switch is fabricated using the method described above. When the MEMS switch is in the on state, there is a gap between the switch beam 10 and the signal line 2, forming an on-state capacitance between them. When the MEMS switch is in the off state, since the orthogonal projection of the conductive part 9 on the substrate 3 lies within the orthogonal projection of the accommodating hole 8 on the substrate 3, and the conductive part 9 passes through the accommodating hole 8, a first off-state capacitance is formed between the switch beam 10 and the signal line 2, and a second off-state capacitance is formed between the conductive part 9 and the switch beam 10. By introducing the second off-state capacitance through the conductive part 9 and the accommodating hole 8, the off-state capacitance is effectively increased, thereby effectively improving the capacitance ratio between the off-state capacitance and the on-state capacitance, and thus improving the radio frequency performance of the MEMS switch.

[0083] Optionally, in this embodiment of the application, before fabricating the signal line 2 on the substrate 3, the fabrication method further includes: fabricating an insulating layer 7 on the substrate 3; the above-mentioned fabrication of the signal line 2 on the substrate 3 includes: fabricating two ground lines 1 on both sides of the signal line 2, the signal line 2 being located between the two ground lines 1, and the signal line 2 being spaced apart from and insulated from the ground lines 1.

[0084] like Figure 12 As shown in the embodiments of this application, in specific implementation, a gold film layer is first deposited or electroplated on the substrate 3, and then the gold film layer is patterned through a patterning process to form signal line 2 and ground line 1. Optionally, the gold film layer is patterned by wet etching.

[0085] Optionally, in this embodiment of the application, the conductive portion 9 is fabricated on the side of the signal line 2 away from the substrate 3, including: fabricating a dielectric layer 4 on the side of the signal line 2 away from the substrate 3 by a patterning process, wherein the dielectric layer 4 has through holes to expose the signal line 2; and fabricating a conductive portion 9 on the side of the dielectric layer 4 away from the substrate 3 by a patterning process, wherein the conductive portion 9 fills the through holes and a portion of the conductive portion 9 protrudes from the dielectric layer 4.

[0086] In this embodiment, specifically, SiNX is first deposited on the side of signal line 2 away from substrate 3 using plasma-enhanced chemical vapor deposition (PECVD), and then patterned to form dielectric layer 4 using reactive ion etching (RIE) technology. A via is formed in the center of dielectric layer 4 (e.g., a hole is drilled in the center of the dielectric layer 4 to form a through-hole). Figure 13 As shown), a gold film layer is deposited on the side of the dielectric layer 4 away from the substrate 3, and the deposited gold film layer fills the vias of the dielectric layer 4. Then, the gold film layer is patterned using a patterning process to form the conductive portion 9 (as shown). Figure 14 (As shown).

[0087] The conductive part 9, the dielectric layer 4, and the through hole are prepared using the above method. The through hole is used to avoid the conductive part 9, facilitating the connection of one end of the conductive part 9 to the signal line 2, while allowing the other end of the conductive part 9 to protrude from the dielectric layer 4. In this way, when the microelectromechanical system switch is in the off state, a second off-state capacitor can be formed between the conductive part 9 and the switch beam 10.

[0088] Optionally, in this embodiment, fabricating the switch beam 10 on the side of the conductive portion 9 away from the substrate 3 includes: fabricating a sacrificial layer 11 on the side of the conductive portion 9 away from the substrate 3, the sacrificial layer 11 covering the conductive portion 9, the signal line 2, and part of the ground line 1 (i.e., part of the ground line 1 is exposed and not covered by the sacrificial layer 11); fabricating a conductive layer on the side of the sacrificial layer 11 away from the substrate 3 by a patterning process, the conductive layer covering the sacrificial layer 11, and the conductive layer being connected to both ground lines 1; performing a patterning process on the conductive layer to form an accommodating hole, and removing the sacrificial layer 11 to form the switch beam 10.

[0089] In this embodiment, specifically, a polyimide film is first spin-coated on the side of the conductive portion 9 away from the substrate 3, and the polyimide film is patterned using RIE to form a sacrificial layer 11. The sacrificial layer 11 covers the conductive portion 9, the signal line 2, and part of the ground line 1 (e.g., ...). Figure 15 (as shown); then a gold film layer is deposited on the sacrificial layer 11, and the gold film layer is patterned using a patterning process to form a conductive layer (such as...). Figure 16 (as shown); then, the conductive layer is patterned using a patterning process to form accommodating vias (such as...). Figure 17 (as shown); finally, the sacrificial layer 11 is removed to form the switch beam 10 (as shown). Figure 18 (As shown).

[0090] In this embodiment, the substrate 3 is made of silicon, the signal line 2, ground line 1, and 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 materials are not limited to these; the substrate material can also be glass, sapphire, silicon carbide, Si (silicon), GaAs (gallium arsenide), etc., and the signal line 2, ground line 1, and switch beam 10 can also be any one of copper, iron, silver, gold, aluminum, nickel, or any combination thereof. The sacrificial layer material can also be photoresist, BPSG (borophosphosilicate glass), etc.

[0091] It should be noted that the above patterning process includes the coating, exposure, development, etching of photoresist, and the removal of part or all of the photoresist.

[0092] By applying the embodiments of this application, at least the following beneficial effects can be achieved:

[0093] When the microelectromechanical system (MEMS) switch is in the ON state, an ON-state capacitance is formed between the switch beam and the signal line; when the MEMS switch is in the OFF state, a first OFF-state capacitance is formed between the switch beam and the signal line, and a second OFF-state capacitance is formed between the conductive part and the switch beam. This embodiment introduces one or more pairs of second OFF-state capacitances between the switch beam and the signal line, effectively increasing the OFF-state capacitance while having almost no effect on the ON-state capacitance. This effectively increases the capacitance ratio of the OFF-state to ON-state capacitance of the MEMS switch, thereby improving the RF performance of the MEMS switch. Since this embodiment does not increase the distance between the switch beam body and the dielectric layer, it has almost no effect on the driving voltage. Because it does not reduce the dielectric layer thickness, it is less prone to dielectric breakdown, and the process is simple and easy to manufacture.

[0094] In the embodiments of this application, the microelectromechanical system switch can be applied to the design of radio frequency switches, especially the design of high capacitance ratio MEMS radio frequency switches.

[0095] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in the prior art that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0096] In the description of this application, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate directions or positional relationships based on the exemplary directions or positional relationships shown in the accompanying drawings. They are used to facilitate the description or simplification of the embodiments of this application and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0097] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0098] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0099] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0100] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown sequentially according to the arrows, the order in which these steps are implemented is not limited to the order indicated by the arrows. Unless explicitly stated herein, in some implementation scenarios of this application, the steps in each process can be executed in other orders as required. Moreover, some or all of the steps in each flowchart may include multiple sub-steps or multiple stages based on the actual implementation scenario. Some or all of these sub-steps or stages may be executed at the same time or at different times. In scenarios where the execution times are different, the execution order of these sub-steps or stages can be flexibly configured according to requirements, and this application does not limit this.

[0101] The above description is only a partial implementation of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of the embodiments of this application.

Claims

1. A microelectromechanical system switch, characterized by The micro-electro-mechanical system switch comprises: a substrate; a signal line arranged on one side of the substrate; a switch beam arranged on the side of the signal line away from the substrate, the switch beam being provided with a receiving hole, a projection of the receiving hole on the substrate being located within a projection of the signal line on the substrate; a conductive part connected with the signal line and arranged between the signal line and the switch beam, a projection of the conductive part on the substrate being located within a projection of the receiving hole on the substrate; the number of the conductive part and the receiving hole is one; or the number of the conductive part and the receiving hole is at least two, the conductive part and the receiving hole are arranged one by one, and at least two conductive parts are arranged in an array and at least two receiving holes are arranged in an array.

2. The micro-electro-mechanical system switch according to claim 1, wherein a cross section of the conductive part is circular or polygonal; and / or a cross section shape of the receiving hole is the same as a cross section shape of the conductive part; wherein the cross section is parallel to the substrate.

3. The MEMS switch of claim 1, wherein The micro-electro-mechanical system switch further comprises a dielectric layer arranged on one side of the substrate and covering 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, the other end of the conductive part passes through the through hole and protrudes from the dielectric layer.

4. The MEMS switch of claim 1, wherein The micro-electro-mechanical system switch further comprises a dielectric layer arranged on one side of the substrate and covering 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 or lower than an outer surface of the dielectric layer away from the substrate; in a direction parallel to the substrate, a size of the receiving hole is greater than a sum of sizes of the conductive part and the dielectric layer.

5. The micro-electro-mechanical system switch according to any one of claims 1 to 4, wherein the micro-electro-mechanical system switch further comprises a ground wire arranged on one side of the signal line, the ground wire is spaced apart from and insulated from the signal line; one end of the switch beam is connected with the ground wire; and / or the micro-electro-mechanical system switch further comprises an insulating layer arranged between the substrate and the signal line.

6. A method of fabricating a microelectromechanical system switch, comprising: The micro-electro-mechanical system switch comprises: providing a substrate, and preparing a signal line on the substrate; preparing a conductive part on the side of the signal line away from the substrate; preparing a switch beam on the side of the conductive part away from the substrate, the switch beam being provided with a receiving hole, a projection of the receiving hole on the substrate being located within a projection of the signal line on the substrate, and a projection of the conductive part on the substrate being located within a projection of the receiving hole on the substrate.

7. The preparation method of the micro-electro-mechanical system switch according to claim 6, wherein before the signal line is prepared on the substrate, the method further comprises preparing an insulating layer on the substrate; the signal line is prepared on the substrate, comprising: two ground wires are prepared on two sides of the signal line, the signal line is located between the two ground wires, and the signal line is spaced apart from and insulated from the ground wires.

8. The preparation method of the micro-electro-mechanical system switch according to claim 7, wherein The conductive part is prepared on the side of the signal line away from the substrate, comprising: A dielectric layer is prepared on the side of the signal line away from the substrate by a patterning process, and the dielectric layer is provided with a through hole to expose the signal line; A conductive part is prepared on the side of the dielectric layer away from the substrate by a patterning process, and the conductive part is filled in the through hole, and part of the conductive part protrudes from the dielectric layer.

9. The method of claim 8, wherein the MEMS switch is formed by: The switch beam is prepared on the side of the conductive part away from the substrate, comprising: A sacrificial layer is prepared on the side of the conductive part away from the substrate, covering the conductive part, the signal line and part of the ground wire; A conductive layer is prepared on the side of the sacrificial layer away from the substrate by a patterning process, covering the sacrificial layer, and the conductive layer is connected with the two ground wires; The conductive layer is subjected to a patterning process to form the accommodation hole, and the sacrificial layer is removed to form the switch beam.

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