[0039] The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar 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 exemplary, only used to explain the present invention, and should not be construed as a limitation of the present invention.
[0040] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc. is based on the attached The orientation or positional relationship shown in the figures is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated combination or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a reference to the present invention. Invention limitations. In addition, during the description of the embodiments of the present invention, the positional relationships of components such as "upper", "lower", "front", "rear", "left", and "right" in all figures are expressed as figure 1 as standard.
[0041] The present invention will be further described below in conjunction with the accompanying drawings:
[0042] like figure 1 , 2 As shown, it is an overall structural diagram and a top view of an embodiment of the present invention. This embodiment provides a radio frequency MEMS switch with a straight plate type upper electrode 12 structure. The radio frequency MEMS switch includes a substrate 1, a microwave transmission line, and a driving electrode 4. Upper electrode 12 , contact 9 , first anchor point 8 , second anchor point 10 , third anchor point 11 , air bridge 14 , release hole 13 . The substrate 1 is used as the carrier structure of the radio frequency MEMS switch, carrying the microwave transmission line, the driving electrode 4, the upper electrode 12, the contact 9, the first anchor point 8, the second anchor point 10, the third anchor point The anchor point 11, the air bridge 14, the release hole 13, when the driving electrode 4 applies a driving voltage, an electrostatic force is generated between the upper electrode 12 and the driving electrode 4, so that the upper electrode 12 faces the direction of the microwave transmission line Bending is generated and is in contact with the microwave transmission line. At this time, the radio frequency MEMS switch is in an open state; when the driving electrode 4 does not apply a driving voltage, the upper electrode 12 and the microwave transmission line are disconnected from each other. At this time , the RF MEMS switch is in an off state.
[0043] The substrate 1 has a cuboid structure, and the microwave transmission line is arranged on the surface of the substrate 1. 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 Fixed anchor point 8 , second fixed anchor point 10 , third fixed anchor point 11 , air bridge 14 , 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 are perpendicular to the bottom edge of the substrate 1, and the two first ground lines 2 and the second ground lines are 7 are respectively disposed on both sides of the first signal line 3 and the second signal line 6 and have the same distance from the first signal line 3 and the second signal line 6 .
[0044]The materials of the substrate 1 are glass, ceramics and high-resistance silicon. Due to the low electrical conductivity of these types of materials, low-loss characteristics when transmitting radio frequency signals are ensured.
[0045] The first signal line 3 and the second signal line 6 are disconnected at the middle position, that is, at the center position of the substrate 1, to form a fracture. The fracture divides the microwave transmission line into two sections, which are defined here. For the first signal line 3 and the second signal line 6 , the driving electrode 4 is arranged in the fracture, that is, the driving electrode 4 is fixedly arranged at the center position of the substrate 1 .
[0046] An upper electrode 12 is arranged on the end surface of the first signal line 3 close to the fracture, and the first signal line 3 and the upper electrode 12 are fixedly arranged through the first fixing anchor point 8 . 12 is a cuboid structure. Since the microwave transmission line is a coplanar waveguide structure, the characteristic impedance is an important parameter of the coplanar waveguide. In the manufacturing process, the characteristic impedance of the input and output ports of the switch is required to be equal to the characteristic impedance of the radio frequency system, so as to achieve the matching characteristics of the ports.
[0047] like image 3 , 4 As shown in , 5, the straight plate-type upper electrode 12 is designed as a rectangular parallelepiped structure, the process is simple, the realization is easy, and the radiation loss is reduced.
[0048] For example, if the characteristic impedance is 50 ohms, the width of the first signal line 3 and the second signal line 6 in the coplanar waveguide or the width of the first signal line 3 and the second signal line 6 and the first ground line 2 in the coplanar waveguide, and The distance between the second ground lines 7 and the structure size of the coplanar waveguide are obtained, so as to perform the radio frequency MEMS switch.
[0049] like Figure 6-7 As shown, the upper electrode 12 has holes, and each release hole 13 has a diameter of 6-10 μm to form an array of release holes 13. The release hole array includes 3-4 rows, which are arranged according to the length direction of the signal lines. The number of release holes in any row is 6-10; the release hole spacing is 10-20 μm. Compared with the non-regular racket-type upper electrode structure, the distances between the upper electrode 12 and the first ground wire 2 and the second ground wire 7 are easier to match, and easier to implement in the process.
[0050] In the manufacturing process of the radio frequency MEMS switch, the sacrificial layer is released by dry method, and the main step is to bombard it with oxygen plasma, and the oxygen cannot fully contact the sacrificial layer without the release hole 13; the above-mentioned release hole is added. After the 13 array, it can make it more fully contact with the sacrificial layer. Only the data of the experimental group is obtained. The diameter of each release hole 13 in this group is 8 μm, forming an array of release holes 13. The release holes 13 can be set in 3 rows, and the release hole spacing 10-20μm.
[0051] The upper electrode 12 is structured with holes to form an array of release holes 13, so as to improve the release efficiency of the sacrificial layer, and at the same time, the air damping of the up and down movement of the electrode plate can be reduced, and the switching speed can be improved.
[0052] like Figure 8 , 9 As shown, the contact 9 is provided on the lower surface of one end of the upper electrode 12 close to the second signal line 6, and the upper electrode 12 is connected with the second signal line 6 through the contact 9, so The number of the contacts 9 is one, and is arranged on the lower electrode 5 . like Figure 10 , 11 , 12 and 13, the shape of the contact 9 is one of a cuboid, a hemisphere or a cone.
[0053] like Figure 14 , 15 , 16 , the air bridge 14 is fixed on the ground wire 7 through the second fixing anchor point 10 and the third fixing anchor point 11 . The air bridge 14 is a rectangular parallelepiped structure, and the two ends are fixed on the second fixed anchor point 10 and the third fixed anchor point 11, and the two fixed anchor points are respectively fixed on the two ends of the second ground wire 7 of the microwave transmission line, which is convenient for lead wires. Passing 15 is beneficial to improve the miniaturization of the switch.
[0054] The principle of the invention is: applying the radio frequency MEMS switch of the present invention, when the driving electrode 4 does not apply a driving voltage, 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, so that the The switch is off. When a driving voltage is applied to the driving electrode 4, as the voltage increases, the electrostatic force between the upper electrode 12 and the driving electrode 4 also increases, so that the upper electrode 12 is bent and connected to the first signal line 3 of the microwave transmission line, and the second signal line 3 of the microwave transmission line. The contacts 9 of the two signal lines 6 are in contact, so that the switch is turned on. In the present invention, the straight-type upper electrode 12 has a cuboid structure. Compared with the structure of the conventional switch upper electrode 12, its shape is simple and regular, which facilitates the connection between the upper electrode 12 and the first ground wire 2 and the second ground wire 7 of the coplanar waveguide. characteristic impedance matching. It is easy to implement in process processing, suitable for mass production, and improves the yield of the switch. The invention also adopts a single-contact 9 structure, which can effectively improve the reliability problem caused by double-contact virtual connection and enhance the contact characteristics of the switch. , reduce the weak contact, avoid switch ablation and adhesion, so that the life of the switch has been greatly improved.
