CN114758928A

CN114758928A - Straight plate type practical radio frequency MEMS switch

Info

Publication number: CN114758928A
Application number: CN202210442525.5A
Authority: CN
Inventors: 李孟委; 吴倩楠; 刘秋慧; 张一飞; 王莉
Original assignee: North University of China
Current assignee: North University of China
Priority date: 2017-07-24
Filing date: 2017-07-24
Publication date: 2022-07-15
Also published as: CN107437482A

Abstract

A straight-plate type practical radio frequency MEMS switch is composed of a substrate, a microwave transmission line, a driving electrode, a lower electrode, a contact, an upper electrode, a fixed anchor point, an air bridge and a release hole, wherein the microwave transmission line, the driving electrode and the lower electrode are arranged on the substrate, the driving electrode is arranged below the upper electrode, the upper electrode is of a straight-plate type structure, a hole is formed in the upper electrode to form a release hole array, the fixed end of the upper electrode is fixed on the microwave transmission line through the fixed anchor point, and a single contact is arranged on the lower electrode. Avoid switch ablation and adhesion, make the life-span of switch obtain great improvement.

Description

Straight plate type practical radio frequency MEMS switch

The application is a divisional application of an invention patent with a parent case name of a straight plate type practical radio frequency MEMS switch; the parent application has the application number: CN 201710605260.5; the application date of the parent application is as follows: 2017.07.24.

Technical Field

The invention belongs to the technical field of radio frequency MEMS, and particularly relates to a straight-plate type practical radio frequency MEMS switch.

Background

The radio frequency MEMS switch has the advantages of small insertion loss, low power consumption, low cost, high linearity and the like, can be used in a reconfigurable circuit, including an attenuator, a phase shifter, a filter, an antenna and the like, and can also be used in a subsystem, including signal path selection, a transmitting/receiving (T/R) component, a beam forming antenna array and the like. Radio frequency MEMS switches are capable of reducing the size, weight and cost of reconfigurable systems to a large extent, becoming an indispensable important technology for the 21 st century.

At present, the research institutions of the domestic radio frequency MEMS switch mainly comprise units such as a middle electric group thirteen institute, a middle electric group fifty-five institute, Qinghua university, Beijing university, southeast university, and China and North university. For example, southeast university discloses a thermally actuated rf mems switch (application number: CN201510453346.1), which adopts a latch-type switch structure, and drives a cantilever beam through a V-shaped beam latch, so that a latch hook at the tail end of the cantilever beam and a latch hook at the tail end of another cantilever beam cooperate to latch, thereby completing the on/off operation of the switch. A radio frequency MEMS switch designed by Qinghua university adopts an irregular racket-shaped upper electrode structure with one end fixed and the other end free, and completes the on-off operation between metal-metal contacts by controlling the motion of a metal arm, thereby completing the on-off operation of signals. However, the upper electrode structures of the two switches are relatively complex, the processing difficulty of the process is high, and the yield of the switches is easily reduced.

Disclosure of Invention

The invention aims to design a straight-plate type practical radio frequency MEMS switch aiming at the defects of the background technology so as to improve the yield of the switch.

The specific technical scheme of the invention is as follows:

the invention provides a straight-plate type practical radio frequency MEMS switch, which mainly comprises a substrate, a microwave transmission line, a driving electrode, a lower electrode, a contact, an upper electrode, a fixed anchor point, an air bridge and a release hole; the microwave transmission line, drive electrode 4 and bottom electrode 5 set up on substrate 1, and drive electrode 4 is located the below of upper electrode 12, and upper electrode 12 is the straight plate type structure, and at 12 trompils of upper electrode, form the release hole array, the stiff end of upper electrode 12 is fixed on the microwave transmission line through first anchor point 8, is equipped with single contact 9 on bottom electrode 5.

The substrate 1 is a cuboid structure.

The radio frequency MEMS switch component comprises a microwave transmission line for transmitting signals, an upper electrode 12 for controlling the on-off of the signals, a driving electrode 4, a contact 9, a first fixed anchor point 8, a second fixed anchor point 10, a third fixed anchor point 11 and an air bridge 14.

The straight-plate-type upper electrode 12 is of a cuboid structure and is fixedly arranged above the microwave transmission line.

The upper electrode 12 is provided with holes, and the diameter of the release holes 13 is 6-10 μm, so that a release hole array is formed. The release hole array comprises 3-4 rows which are arranged along the length direction of the signal line, and the number of the release holes in any row is 6-10; the spacing between the release holes is 10-20 μm.

The driving electrode 4 is correspondingly arranged at a position below the upper electrode 12.

The microwave transmission line is fixedly arranged on the substrate 1, and comprises at least one signal line and at least two ground wires.

The signal line is arranged in the center of the substrate 1, and the first ground line 2 and the second ground line 7 are arranged in parallel on two sides of the first signal line 3 and the second signal line 6.

The middle positions of the first signal wire 3 and the second signal wire 6 are disconnected to form a fracture, and two sections of signal wires are defined as the first signal wire 3 and the second signal wire 6.

The upper electrode 12 is disposed above the discontinuity.

And the upper electrode 12 is fixedly arranged at the position, close to the fracture end, of the first signal line 3 through the first fixed anchor point 8, and the upper electrode 12 and the first signal line 3 form a cantilever structure.

And the second signal wire 6 is arranged close to the fracture end, the contact 9 is arranged, and the number of the contact 9 is one and is positioned above the lower electrode 5. The contact 9 is in the shape of one of a cuboid, a hemisphere or a cone.

The air bridge 14 is rectangular, the air bridge 14 is fixed on the second ground 7 by the second fixing anchor 10 and the third fixing anchor 11, and the air bridge 14 and the second ground 7 form a space through which a lead can pass.

Compared with the prior art, the invention has the following beneficial effects:

compared with the prior art, the invention has obvious advancement, the upper electrode is of a cuboid structure, and compared with the upper electrode structure of the traditional switch, the shape of the upper electrode is simple and regular, the characteristic impedance matching between the upper electrode and the coplanar waveguide ground wire is convenient, the invention is easy to realize in process processing, is suitable for batch production, and improves the yield of the switch. The invention also adopts a single-contact structure to effectively improve the reliability problem caused by the virtual connection of double contacts, enhance the contact characteristic of the switch, reduce weak contact, avoid ablation and adhesion of the switch and greatly prolong the service life of the switch.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an overall structural view of the radio frequency MEMS switch;

FIG. 2 is a top view of the overall structure of the RF MEMS switch;

FIG. 3 is a switch structure diagram of the RF MEMS switch;

FIG. 4 is a top view of a switch structure of the RF MEMS switch;

FIG. 5 is a front view of the switch structure of the RF MEMS switch;

FIG. 6 is a top electrode structure of the RF MEMS switch;

FIG. 7 is a top view of the top electrode structure of the RF MEMS switch;

FIG. 8 is a block diagram of a rectangular contact of the RF MEMS switch;

FIG. 9 is a top view of a rectangular contact structure of the RF MEMS switch;

FIG. 10 is a view of the hemispherical contact structure of the RF MEMS switch;

FIG. 11 is a top view of a hemisphere contact structure of the RF MEMS switch;

FIG. 12 is a view of a cone contact structure of the RF MEMS switch;

FIG. 13 is a top view of a cone contact structure of the radio frequency MEMS switch;

FIG. 14 is a schematic view of an air bridge structure of the RF MEMS switch;

FIG. 15 is a top view of an air bridge structure of the RF MEMS switch;

fig. 16 is a front view of the air bridge structure of the rf MEMS switch.

As shown in the figures, the list of reference numbers is as follows:

1. the device comprises a substrate, 2, a first ground wire, 3, a first signal wire, 4, a driving electrode, 5, a lower electrode, 6, a second signal wire, 7, a second ground wire, 8, a first fixing anchor point, 9, a contact, 10, a second fixing anchor point, 11, a third fixing anchor point, 12, an upper electrode, 13, a release hole, 14, an air bridge, 15 and a lead.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the combination or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, are not to be construed as limiting the present invention. In addition, in the description process of the embodiment of the present invention, the positional relationships of the devices such as "upper", "lower", "front", "rear", "left", "right", and the like in all the drawings are based on fig. 1.

The invention is further described below with reference to the accompanying drawings:

as shown in fig. 1 and 2, an overall structure diagram and a top view of an embodiment of the present invention are provided, and the embodiment provides a radio frequency MEMS switch with a straight-plate type upper electrode structure, where the radio frequency MEMS switch includes a substrate 1, a microwave transmission line, a driving electrode 4, an upper electrode 12, a contact 9, a first fixing anchor 8, a second fixing anchor 10, a third fixing anchor 11, an air bridge 14, and a release hole 13. The substrate 1 is used as a carrier structure of the radio frequency MEMS switch, bears the microwave transmission line, the driving electrode 4, the upper electrode 12, the contact 9, the first fixing anchor point 8, the second fixing anchor point 10, the third fixing anchor point 11, the air bridge 14 and the release hole 13, when a driving voltage is applied to the driving electrode 4, an electrostatic force is generated between the upper electrode 12 and the driving electrode 4, so that the upper electrode 12 bends towards the direction of the microwave transmission line and is in contact with the microwave transmission line, and at the moment, the radio frequency MEMS switch is in an open state; when the driving voltage is not applied to the driving electrode 4, the upper electrode 12 and the microwave transmission line are disconnected from each other, and at this time, the radio frequency MEMS switch is in a closed state.

The substrate 1 is of a cuboid structure, the microwave transmission line is arranged on the surface of the substrate 1, and the radio frequency MEMS switch comprises the substrate 1, the microwave transmission line, a driving electrode 4, an upper electrode 12, a contact 9, a first fixed anchor point 8, a second fixed anchor point 10, a third fixed anchor point 11, an air bridge 14 and a release hole 13. The microwave transmission line includes a first signal line 3, a second signal line 6, a first ground line 2, and a second ground line 7. The first signal line 3 and the second signal line 6 are located at the center of the substrate 1 and perpendicular to the bottom edge of the substrate 1, and the two first ground lines 2 and the two second ground lines 7 are respectively arranged at two sides of the first signal line 3 and the second signal line 6 and have the same distance with the first signal line 3 and the second signal line 6.

The substrate 1 is made of glass, ceramic and high-resistance silicon, and the low loss characteristic when radio frequency signals are transmitted is ensured due to the low conductivity of the glass, the ceramic and the high-resistance silicon.

The middle positions of the first signal wire 3 and the second signal wire 6, namely the positions overlapped with the center position of the substrate 1, are disconnected to form a fracture, the microwave transmission line is divided into two sections by the fracture, the two sections are defined as the first signal wire 3 and the second signal wire 6, and a driving electrode 4 is arranged in the fracture, namely the driving electrode 4 is fixedly arranged at the center position of the substrate 1.

First signal line 3 is close set up upper electrode 12 on the fracture terminal surface, first signal line 3 with upper electrode 12 end passes through first fixed anchor point 8 is fixed to be set up, straight board-like upper electrode 12 is the cuboid structure, because microwave transmission line is coplanar waveguide structure, and characteristic impedance is coplanar waveguide's important parameter. In the preparation process, the characteristic impedance of the input/output port of the switch is required to be equal to the characteristic impedance of a radio frequency system so as to achieve the matching characteristic of the port.

As shown in fig. 3, 4 and 5, the straight-plate-type upper electrode 12 is designed to be a rectangular parallelepiped structure, which is simple in process, easy to implement, and reduces radiation loss.

For example, the characteristic impedance is 50 ohms, the widths of the first signal line 3 and the second signal line 6 of the coplanar waveguide or the distances between the first signal line 3 and the second signal line 6 of the coplanar waveguide and the first ground line 2 and the second ground line 7 are calculated, and the structural size of the coplanar waveguide is obtained, so that the radio frequency MEMS switch is performed.

As shown in fig. 6 to 7, the upper electrode 12 is provided with openings, each release hole 13 has a diameter of 6 to 10 μm, and an array of release holes is formed, the array of release holes includes 3 to 4 rows, and the number of the release holes in any row is 6 to 10, and the release holes are arranged along the length direction of the signal line; the spacing between the release holes is 10-20 μm. Compared with an irregular racket-shaped upper electrode structure, the distances from the upper electrode 12 to the first ground wire 2 and the second ground wire 7 are easier to match, and the technical processing is easier to realize.

In the manufacturing process of the radio frequency MEMS switch, the sacrificial layer is released by a dry method, the main step is to bombard the sacrificial layer by using oxygen plasma, and oxygen cannot be fully contacted with the sacrificial layer under the condition without the release holes 13; the array of the release holes can be added to make full contact with the sacrificial layer, and only experimental data is obtained, wherein the diameter of each release hole 13 in the group is 8 μm, the array of the release holes is formed, 3 rows of the release holes 13 can be arranged, and the distance between the release holes is 10-20 μm.

The upper electrode 12 is provided with holes to form a release hole array, so that the release efficiency of the sacrificial layer is improved, and meanwhile, the air damping of the up-and-down movement of the electrode plate can be reduced, and the switching speed is improved.

As shown in fig. 8 and 9, the contact 9 is disposed on the lower surface of one end of the upper electrode 12 close to the second signal line 6, the upper electrode 12 is electrically connected to the second signal line 6 through the contact 9, and the number of the contacts 9 is one, and the upper electrode is disposed on the lower electrode 5. As shown in fig. 10, 11, 12 and 13, the contact 9 has a shape of one of a rectangular parallelepiped, a hemisphere and a cone.

As shown in fig. 14, 15, and 16, the air bridge 14 is fixed to the ground wire 7 by the second fixing anchor 10 and the third fixing anchor 11. The air bridge 14 is of a cuboid structure, two ends of the air bridge are fixed on the second fixed anchor point 10 and the third fixed anchor point 11, the two fixed anchor points are respectively fixed at two ends of the second ground 7 of the microwave transmission line, the lead 15 can conveniently pass through the air bridge, and the miniaturization of the switch is facilitated to be improved.

The invention principle is as follows: when the driving voltage is not applied to the driving electrode 4, the upper electrode 12 is disconnected from the first signal line 3 of the microwave transmission line and the contact 9 of the second signal line 6 by applying the radio frequency MEMS switch of the invention, so that the switch is in a closed state. When a driving voltage is applied to the driving electrode 4, the electrostatic force between the upper electrode 12 and the driving electrode 4 increases with the increase of the voltage, so that the upper electrode 12 is bent to contact with the contacts 9 of the first signal line 3 and the second signal line 6 of the microwave transmission line, and the switch is turned on. In the invention, the straight-plate type upper electrode 12 is in a cuboid structure, compared with the structure of the traditional switch upper electrode 12, the shape of the straight-plate type upper electrode is simple and regular, and the characteristic impedance matching of the upper electrode 12 and the first ground wire 2 and the second ground wire 7 of the coplanar waveguide is convenient. The invention also adopts a single-contact 9 structure, can effectively improve the reliability problem caused by double-contact virtual connection, enhances the contact characteristic of the switch, reduces weak contact, avoids ablation and adhesion of the switch, and greatly improves the service life of the switch.

In conclusion, the straight-plate type practical radio frequency MEMS switch has a simple and regular shape, and facilitates the characteristic impedance matching between an upper electrode and a coplanar waveguide ground wire; the method is easy to realize in process machining, is suitable for batch production, and further improves the yield of the switch.

The above-mentioned embodiments are only for convenience of description of the invention, and are not intended to limit the invention in any way, and it will be apparent to those skilled in the art that the invention can be embodied in many different forms without departing from the spirit and scope of the invention.

Claims

1. A bar-type practicalized radio frequency MEMS switch, the switch comprising:

the microwave transmission line comprises a first signal line and a second signal line, and a fracture is formed in the middle of the first signal line and the second signal line;

the fixed end of the upper electrode is fixed on the first signal line through a first fixed anchor point, and the middle part and the other end of the upper electrode extend above the level of the substrate;

the upper surface of the lower electrode is provided with a single contact, the single contact is arranged below the other end of the upper electrode, and the lower electrode is connected with the second signal wire;

the driving electrode is arranged at the center of the upper surface of the substrate, the driving electrode is arranged below the upper electrode, and a release hole array is arranged at the position of the upper electrode, which corresponds to the driving electrode;

when the driving voltage is applied to the driving electrode, the upper electrode can be bent to be in contact with the single contact; the upper electrode is disconnected from the single contact when the driving voltage is not applied to the driving electrode.

2. The bar type of practical rf MEMS switch of claim 1, wherein the upper electrode has a rectangular structure.

3. The bar type of practical radio frequency MEMS switch according to claim 1 or 2, wherein the release hole array comprises a plurality of release holes arranged in an array;

the release hole array comprises 3-4 rows of release holes, the release holes are arranged in the length direction of the signal line, and the number of any row of release holes is 6-10;

the diameter of the release holes is 6-10 μm, and the distance between any two adjacent release holes in each row or column is 10-20 μm.

4. The bar type practical rf MEMS switch of claim 1, wherein the microwave transmission line further includes a first ground line and a second ground line, the first ground line and the second ground line being respectively disposed at two sides of the upper electrode and the lower electrode.

5. The bar type practical radio frequency MEMS switch according to claim 4, wherein the second ground is divided into two segments, and the two segments are connected by an air bridge; and two ends of the air bridge are fixed with the two sections of the second ground through a second fixed anchor point and a third fixed anchor point respectively.

6. The bar type of practical rf MEMS switch of claim 1, wherein the substrate is made of glass, ceramic or high-resistance silicon.

7. The practical rf MEMS switch of claim 1, wherein the end of the second signal line close to the driving electrode extends out of the lower electrode, and the surface of the lower electrode facing the upper electrode is fixed with the single contact.

8. The bar type practical radio frequency MEMS switch according to claim 4 or 5, wherein the first signal line, the second signal line, the first ground line and the second ground line are cuboids, and the first ground line and the second ground line are equidistantly disposed at two sides of the first signal line and the second signal line, respectively.

9. The bar type practical rf MEMS switch according to claim 5, wherein the air bridge is provided at a position where the second ground line is the shortest distance from the driving electrode.

10. The bar type practical rf MEMS switch according to claim 1, wherein the single contact shape includes but is not limited to rectangular parallelepiped, hemisphere or cone.