CN100373516C - Single pole double throw radio frequency and microwave micromechanical switch with warped membrane structure and fabrication method - Google Patents

Abstract

The invention relates to a single-pole double-throw radio frequency and microwave micromechanical switch with a warped film structure and a manufacturing method thereof. The first concave portion on the first substrate, the first waveguide at the bottom of the first concave portion and the first substrate surface, the first attracting electrode at the bottom of the first concave portion, the conversion conductor on the first substrate surface, and the second substrate the second concave portion of the second concave portion, the second waveguide located at the bottom of the second concave portion and the second substrate surface, the second attracting electrode at the bottom of the second concave portion, the warped elastic dielectric film suspended between the first concave portion and the second concave portion, The composite film is composed of a driving conductive film on a warping elastic dielectric film and a second dielectric film on it. The warped elastic dielectric membrane contains a preset compressive stress not greater than 100MPa. In a steady state, the composite film is in contact with the surface of a certain waveguide, so that the signal of this path remains disconnected, and the composite film is separated from the other waveguide, so that the signal of this path remains conductive. It has the function of state latching and has no static power consumption characteristics.

Description

Single pole double throw radio frequency and microwave micromechanical switch with warped membrane structure and fabrication method

technical field

The invention relates to a single-pole double-throw radio frequency (RF) and microwave micromechanical switch with a state latch function of a warping film structure and a manufacturing method thereof. It is produced by micro-electromechanical processing technology and can be used in microwave communication systems. It belongs to the field of Micro-Electro-Mechanical Systems (MEMS).

Background technique

Microwave and radio frequency technologies are widely used in mobile communication, wireless local area network (WLAN), avionics, electronic navigation and positioning, automotive radar, and even medical fields. The market demand is developing rapidly, and RF and microwave technology must meet many requirements such as small and cheap system, low power consumption, multi-function, and high reliability. Compared with traditional technologies, RF MEMS (X, Ka, or Ku band) technology is considered to be a promising development direction. The so-called micro-electromechanical system technology (MEMS) is a new scientific field developed on the basis of microelectronic technology. The devices made by this technology have been widely used in the fields of micro-sensors, micro-actuators, and optical and electrical communications due to their good performance.

In microwave and radio frequency systems, radio frequency switches are important components and are widely used. For example, they can be used for antenna transceiving and signal filtering channel selection in multi-band communication systems. Traditional switches are made of field effect transistors (Field Effect Transistor, or FET) or PIN diodes. Although these devices have low operating voltage and fast operating speed, they have large insertion loss, low isolation, device nonlinearity, Disadvantages such as large intermodulation and large power consumption. When the signal frequency is getting higher and higher, the performance defects of these devices are the bottlenecks that limit their applications. Micromechanical microwave and radio frequency switches manufactured by MEMS technology have the advantages of small insertion loss, high isolation, and small intermodulation. The improvement of these performances is very important for radio frequency communication systems.

A typical single-pole single-throw (SPST) RF micromechanical switch is an electrostatically driven capacitive bypass switch (Charles L. Goldsmith, Zhimin Yao, Susan Eshelman, David Denniston. "Performance of low-loss RF MEMS capacitive switches, IEEE Microwave and Guided Wave Letters, Vol.8, No.8, August 1998), which includes the coplanar waveguide (CPW) on the substrate material, the insulating medium on the middle signal line of the coplanar waveguide, and the ground on both sides of the coplanar waveguide The metal bridge connected by the wire. The signal wire and the metal bridge, as well as the insulating medium and air on the signal wire together form a variable capacitor. When there is a certain static voltage difference on the two plates of the capacitor, due to the effect of electrostatic attraction , the metal bridge will be attracted to the insulating medium on the signal line, thereby changing the capacitance. When the static voltage difference is removed, the metal bridge returns to its original position under the action of elastic restoring force. Due to the capacitive reactance of the capacitor and the signal Frequency dependent, the variable capacitor makes the signal in the signal line either unaffected, or bypassed by the ground line, thereby realizing the switching function.

Single pole double throw (SPDT) RF switches are also widely used. Two SPDT switches are proposed in U.S. Patents 6,580,337 and 6,440,767. The basic structure is to place a single-pole single-throw switch in two output signal paths with the same input port, and the two switches work alternately to achieve single-pole double-throw. double throw. Their single-pole single-throw switches use electrostatically driven cantilever beam switches. A connecting conductor is made at the end of the cantilever beam. When the cantilever beam moves toward the signal line under the action of electrostatic force and the displacement reaches a certain size, the connection at the end The conductor connects the originally disconnected signal line to make it conduct. When the electrostatic force is removed, the cantilever beam returns to its original position under the action of the elastic restoring force, so that the signal path is disconnected. This single-pole double-throw switch has the disadvantage of large volume, and the resistance introduced by the connecting conductor will increase the insertion loss. The above-mentioned SPDT switches all require electrostatic force to maintain their switching state in a certain path. When the electrostatic force is removed, the switch state will no longer be maintained, that is, these micromechanical switches do not have a state latch function.

It can be seen that, so far, there has not been a report on a single-pole double-throw radio frequency and microwave micromechanical switch with a state latch function, small size, and low power consumption. In addition, the insertion loss of the switch is also very small.

Contents of the invention

The purpose of the invention is to design a single-pole double-throw radio frequency and microwave micromechanical switch with a state latch function, small size, and low power consumption and a preparation method thereof, and the insertion loss of the switch is also very small.

The single pole double throw radio frequency and microwave MEMS switch with state latch function provided by the present invention is characterized in that the switch consists of a first recess on the first substrate, a first waveguide located at the bottom of the first recess and on the surface of the first substrate , the first attracting electrode at the bottom of the first recess, the conversion conductor on the surface of the first substrate, the second recess on the second substrate, the second waveguide at the bottom of the second recess and on the surface of the second substrate, the bottom of the second recess The second attracting electrode, the warped elastic dielectric film suspended between the first recess and the second recess, the driving conductive film on the warped elastic dielectric film and the second dielectric film thereon.

The warped elastic dielectric film may be in the first locked state, that is, bent toward the first substrate, and the middle part of the lower surface of the elastic dielectric film is in contact with the signal line in the first waveguide; or, the warped elastic dielectric film It can be in the second locked state, that is, it is bent toward the second substrate, and the middle part of the upper surface of the second dielectric film is in contact with the signal line in the second waveguide.

The initial state of the warped elastic dielectric film may be in the first locked state, or in the second locked state. The conversion conductor on the first substrate is connected to the second waveguide and other components on the first substrate.

There is a prestress in the elastic dielectric membrane, when the prestress reaches a certain size, the initial state of the elastic dielectric membrane is any one of the above states, and at the same time, the existence of the prestress makes the state of the elastic dielectric membrane have a latch The characteristic, that is, the elastic membrane remains in this state when it is not affected by an external force, until it is changed to another state by an external force. The prestress in the elastic medium membrane is a compressive stress not greater than 100Mpa.

The depth difference between the first recess and the second recess is not greater than 0.2 microns, and the depth of the first recess and the second recess is not less than 1 micron and not greater than 5 microns.

The driving conductive film is electrically insulated from the first waveguide, and is also electrically insulated from the second waveguide.

The state latching function of the SPDT radio frequency and microwave micromechanical switch described in the present invention is realized by utilizing the bistable warping principle of a double-terminal fixed-supported film under critical compressive stress conditions, and its principle is expressed as follows:

Consider a rectangular film with length a and width b, the side with length a has no freedom constraint, and the side with width b is fixed. If there is no stress or tensile stress in the film, the film remains flat. When the film is subjected to longitudinal compressive stress, the film has a tendency to warp in the transverse direction. When the compressive stress increases to a certain critical value, the stable state of the film is destroyed, and transverse warpage occurs until the film reaches another stable state. This steady state is one of two possible steady states. The magnitude of the critical stress required to produce warpage is given by the following formula:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; cr</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; Et</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}$

Among them, σ _cr is the critical stress, E is the Young's modulus of the material constituting the film, t is the film thickness, and v is Poisson's ratio.

The SPDT radio frequency and microwave micromechanical switch of the present invention adopts the working principle of an electrostatically driven capacitive bypass switch, which is illustrated in FIG. 1 , and the waveguide structure is taken as an example of a coplanar waveguide.

As shown in FIG. 1( a ), a coplanar waveguide (CPW) composed of a transmission line 12 and a ground plate 13 is formed on a base substrate 11 , and a metal film 15 is formed on a dielectric film bridge 14 . The metal film 15, the transmission line 12, the dielectric film 14 and the air between them form a variable capacitance. When there is no electrostatic voltage between the grounding plate 13 and the metal film 15, the lower surface of the 14 is higher than the upper surface of the 12 by a certain distance, and because the dielectric constant of the air is very small, the variable capacitance value is very small. At high frequencies, the capacitive reactance of the variable capacitor is large. Signals in the transmission line 12 are reflected very little by the switches. The switch is now on.

As shown in Figure 1 (b), when a certain electrostatic voltage is applied between the metal film 15 and the ground plate 13, the electrostatic force generated by electrostatic induction makes the dielectric film bridge 14 and the metal film 15 move downward until the lower surface of the ground plate 14 Fitting with the upper surface of 12. At this time, since the dielectric constant of 14 is much larger than that of air, the variable capacitance is very large. At high frequencies, shorting the signal in the transmission line 12 to ground, the signal is almost completely reflected by the switch. At this point the switch is in the off state.

The manufacturing method of the SPDT radio frequency and microwave micromechanical switch of the present invention adopts the surface micromachining technology, and comprises the following steps: a) forming a first recess on the first substrate; b) forming the bottom of the first recess and the second Forming the first waveguide, the first attracting electrode and the conversion conductor on the surface of a substrate; c) forming the second recess on the second substrate; d) forming the second waveguide and the second attracting electrode at the bottom of the second recess and the surface of the second substrate. Electrode; e) filling the sacrificial layer material in the first recess; f) planarizing the sacrificial layer material so that its upper surface is parallel to the upper surface of the first substrate, and the height difference between the two is not less than 0.1 micron and not greater than 0.5 micron; g) forming the aforementioned elastic medium layer on the upper surface of the first substrate and the sacrificial layer in the first recess; h) forming the aforementioned driving conductive layer on the aforementioned elastic medium; i) forming a second dielectric layer on the aforementioned driving conductive layer; j ) etching the second dielectric layer to form a second dielectric film; k) etching the conductive layer and the elastic dielectric layer to form the elastic dielectric film, the drive conductive film, the drive conductive film lead electrode and the sacrificial layer corrosion hole; 1) etching to remove the sacrificial layer layer, releasing and forming a warped elastic dielectric film; m) bonding the upper surface of the first substrate and the lower surface of the second substrate facing each other, the aforementioned first concave portion and the second concave portion are aligned to form a switch portion cavity, and the second The waveguide and the second attracting electrode are aligned with the switching conductor to form the switching.

According to the present invention, since the warped elastic dielectric film contains a certain amount of preset compressive stress, it can maintain any one of the above two locking states until an external force changes the state. When the warped elastic dielectric film is in the first locked state, the middle part of the lower surface of the elastic dielectric film is in contact with the signal line in the first waveguide, and the capacitance formed by the signal line, the elastic medium layer and the driving conductive layer is relatively large, and the radio frequency signal It is almost completely reflected by the switch, so that the signal is disconnected; at the same time, the upper surface of the second dielectric film is separated from the signal line in the second waveguide by a certain distance, and the signal line, air, the second dielectric layer and the driving conductive layer are separated by a certain distance. The capacitance of the formed structure is very small, so that the reflection of the radio frequency signal by the switch is very small, so the signal transmission of this channel is not affected by the switch and remains on. If a certain static voltage difference is applied on the second attracting electrode and the driving conductive layer, due to the effect of electrostatic attraction, the warped elastic cut-off film changes from the first locked state to the second locked state, that is, the second dielectric film and the first The signal lines in the two waveguides are in contact, and the warped elastic dielectric film is separated from the signal lines in the first waveguide by a certain distance. Similar to the above principle, the signal in the second waveguide is disconnected, and the signal in the first waveguide is turned on. At this time, if the control voltage on the attracting electrode is removed, the warped elastic dielectric film will still maintain the current state under compressive stress, and the switch state is latched.

According to the present invention, the switch uses the technology of bonding the first and second substrates up and down in the manufacturing process, and the size of the components on the two substrates can be made relatively small, while reducing the overall volume of the device, and avoiding the need for two single-pole single-throw The disadvantage of placing the switch on a plane is that the entire switch occupies a large volume and area.

According to the present invention, the switch adopts an electrostatically driven capacitive switch, and there is no static current in the working process of the device, so the device does not consume static power consumption.

According to the present invention, when the switch is in the first locked state or the second locked state, the distance between the second waveguide and the second dielectric film or the distance between the first waveguide and the warped elastic dielectric film is relatively large, and due to the The relative permittivity is very small, so for the waveguide in the conduction state, the equivalent capacitance between it and the driving conductive layer is very small, so that the switch has little influence on the signal, and the insertion loss of the switch is low.

Description of drawings

Fig. 1 is a sectional view of the working principle of the radio frequency switch provided by the present invention. (a) The switch is on (b) The switch is off

Fig. 2 is a three-dimensional view of the radio frequency switch in the present invention. The waveguide structure takes the coplanar waveguide (CPW) structure as an example. For clarity, it is divided into two parts:

Among them, (a) is the first substrate 201, the first concave portion 214, the first coplanar waveguide, the conversion conductor, the sacrificial layer 204 and the three layers composed of the elastic dielectric film 205, the driving conductive film 208 and the second dielectric film 209 Schematic diagram of the composite membrane;

(b) is a schematic diagram of the second substrate 210, the second concave portion 213 and the second coplanar waveguide.

Figure 3(a) and (b) are cross-sectional views along the AB axis corresponding to Figure 2(a) and (b), respectively.

Figure 4(a) and (b) are diagrams of the initial state of the warped elastic dielectric film, and the waveguide structure takes a coplanar waveguide (CPW) structure as an example.

Fig. 5 is a sectional view of the manufacturing process of the SPDT radio frequency switch in the present invention.

(a) First substrate corrosion

(b) Forming the first waveguide and the conversion conductor

(c) Second substrate corrosion

(d) Forming the second waveguide

(e) Filling the sacrificial layer

(f) Sacrificial layer planarization

(g) Deposition of elastic dielectric layer

(h) deposit conductive layer

(i) Deposit the second dielectric layer

(j) Etching the second dielectric layer

(k) Etching the conductive layer and the elastic dielectric layer to form a film

(l) Corrosion of the sacrificial layer to release the composite film

(m) bonding

FIG. 6 is a schematic diagram of the geometry of the three-layer composite film in the radio frequency switch of Example 3. FIG.

Figure 7(a) is a plan view of a coplanar waveguide (CPW) (b) is the microstrip line structure mentioned in Embodiment 4.

In the picture:

11—substrate substrate 12—transmission line 13—ground plate

14—dielectric film bridge 15—metal film

200—Drive Conductive Film Leading Electrode 201—First Substrate

202—the signal line in the first coplanar waveguide

203—Ground in the first coplanar waveguide 204—Sacrificial layer

205—Warping elastic dielectric film 206—Transforming signal lines in conductors

207—Ground wire in the conversion conductor 208—Drive conductive film

209—Second Dielectric Film 210—Second Substrate

211—the signal line in the second coplanar waveguide

212—Ground wire in the second coplanar waveguide

213—the second recess 214—the first recess

215—elastic dielectric layer 216—conductive layer

217—Second Dielectric Layer 601—Corrosion Hole in Sacrificial Layer

701—Signal line in microstrip line 702—Attracting electrode

703—Ground wire in microstrip line

Detailed ways

The features of the present invention are illustrated in detail below through examples, but the present invention is by no means limited to these examples.

Example 1

Schematic diagram of a single pole double throw switch

Please refer to Fig. 2 (a) and (b) first, which are three-dimensional schematic diagrams of the SPDT switch in the present invention. In the schematic diagram, the waveguide structure is taken as an example of a coplanar waveguide (CPW) structure, and the two ground wires in the coplanar waveguide serve as attracting electrodes at the same time. Of course, as mentioned above, the waveguide can also adopt other structures, such as a microstrip line structure, and the attracting electrode can be made separately. For clarity, the diagram is divided into two parts. FIG. 2( a ) is a schematic diagram of the first substrate 201 and components thereon before bonding, and the sacrificial layer has not been corroded yet. FIG. 2( b ) is a schematic diagram of the second substrate 210 and components thereon before bonding. As shown in Figure 2(a), it includes a first substrate 201, a first coplanar waveguide composed of 202 and 203 in the first recess 214 and on the surface of 201, and a first coplanar waveguide composed of 206 and 207 on the surface of 201. The conversion conductor, the sacrificial layer 204 located in the first recess 214, the warped elastic dielectric film 205 (unreleased) formed on the surface of 204, the driving conductive film 208 formed on the surface of 205, and the second dielectric film formed on the surface of 208 209 and the sacrificial layer etching hole 601. The shape of the etching hole in the sacrificial layer may be circular, square or other shapes. As shown in FIG. 2( b ), it includes a second substrate 210 , a second recess 213 formed on 210 , and a second coplanar waveguide composed of 211 and 212 formed on the surface of the second substrate 210 .

3(a) and (b) are cross-sectional views along the AB axis corresponding to the above-mentioned FIGS. 2(a) and (b), respectively. As shown in FIG. 3( a ), before forming the elastic dielectric film 205 on the surface of the sacrificial layer 204 , the surface of the sacrificial layer has been planarized to ensure the flatness of the formed composite film. Both the formed elastic dielectric film 205 and the second dielectric film 209 have a compressive stress not exceeding 100 MPa. Meanwhile, the depths of the first concave portion 214 and the second concave portion 213 are between 1-5 μm.

Example 2

Single pole double throw radio frequency and microwave micromechanical switch method

The single-pole double-throw switch involved in the present invention is manufactured using surface micro-machining technology, and its manufacturing method can be described with reference to the cross-sectional view of the process flow in Figure 5(a)-(m). The waveguide structure still takes the coplanar waveguide (CPW) structure as an example. (a) Form the first concave portion 214 on the first substrate 201; (b) Form the signal line 202 and the ground line 203 in the first waveguide and the signal line of the conversion conductor in the first concave portion 214 and on the surface of the first substrate 201 206 and ground wire 207; (c) form a second concave portion 213 on the second substrate 210; (d) form the signal line 211 and the ground wire 212 in the second waveguide on the surface of the second concave portion 213 and the surface of the second substrate 210 (not shown in the figure); (e) filling the sacrificial layer 204 in the first recess 214; (f) planarizing the sacrificial layer 204; (g) forming a first dielectric layer 215 on the sacrificial layer 204; (h) Form a conductive layer 216 on the first dielectric layer 215; (i) form a second dielectric layer 217 on the conductive layer 216; (j) etch the second dielectric layer 217 to form a second dielectric film 209; (k) etch the conductive Layer 216 and first dielectric layer 215 form driving conductive film 208, warped elastic dielectric film 205, driving conductive film lead-out electrode 200 and sacrificial layer corrosion hole 601; (1) sacrificial layer 204 is etched away to release the three-layer composite film. (m) The upper surface of the first substrate 201 is bonded to the lower surface of the second substrate 210, the first concave portion 214 is aligned with the second concave portion 213 to form a switch cavity, and the second waveguide is aligned with the conversion conductor to form a cavity. convert.

Example 3

The geometry of the three-layer composite film in the SPDT switch of this embodiment is shown in FIG. 6 .

According to the aforementioned manufacturing method, both the first substrate and the second substrate use (100) oriented high-resistance silicon wafers. Etch the first pit on the first substrate, deposit a thin layer of silicon nitride, then sputter Cr/Au with a certain thickness, and form the first pit on the bottom of the first pit and the surface of the first substrate through photolithography and etching. A coplanar waveguide (CPW) and transition conductor. Then fill the sacrificial layer in the first pit, and the material of the sacrificial layer is positive photoresist, such as Shipley S1818 or Shipley4620. The sacrificial layer is planarized using a chemical mechanical polishing process (CMP) so that its surface is parallel to the silicon wafer surface. Next, the first layer of compressive stress silicon nitride, the Cr/Au of the driving conductive layer and the second layer of compressive stress silicon nitride are sequentially deposited on the surface of the sacrificial layer and the surface of the silicon wafer, and the compressive stress in the film is not greater than 100 MPa. Then dry etch the second layer of silicon nitride, the middle Cr/Au layer and the first layer of silicon nitride in sequence to form the second dielectric film 209, the driving conductive film 208, the warped elastic dielectric film 205 and the sacrificial layer etching hole 601. Then 601 is used to etch away the photoresist of the sacrificial layer to release the warped elastic dielectric film. Then etch the second pit on the second substrate, then deposit a thin layer of silicon nitride, and then sputter a certain thickness of Cr/Au, and form it on the bottom of the second pit and the surface of the second substrate through photolithography and etching. a second coplanar waveguide. The two substrates and the components on them are aligned and bonded by bonding to form the cavity of the switch part and the switch.

Since the switch of this embodiment uses compressive stress silicon nitride as the warp elastic dielectric film material, it has a state latch function and is small in size. In addition, due to the geometric shape of the composite film as shown in Figure 6, the elastic constant of the film is small, so that the driving voltage is relatively low and the flatness of the film is good. A thin layer of silicon nitride is deposited on the substrate to reduce substrate loss.

Example 4

In this embodiment, the first and second substrates of the switch use quartz substrates. The main difference from Embodiment 1 is that a microstrip line waveguide structure is used instead of a coplanar waveguide (CPW). The advantage of doing this is that it makes the process implementation easier to control.

Fig. 7(a) shows a coplanar waveguide (CPW) structure, 202 is a signal line, and 203 is a ground line. In microwave transmission, it is important to match the impedance of the waveguide to the impedance of the rest of the system. The characteristic impedance of the coplanar waveguide has a complex nonlinear relationship with the signal line a and the distance b between the signal line and the ground line. In the process, the size of a and b must be strictly controlled to ensure that the impedance of the waveguide is consistent with the design. The technical requirements are also very high. The microstrip line structure shown in Figure 7(b) is composed of a signal line 701 and a ground line 703, and the relationship between its characteristic impedance and the width of the signal line 701 is relatively simple. Relatively easy to control.

Production method: Etch the first pit on the first substrate, then sputter Cr/Au with a certain thickness, and form the signal line of the first microstrip line on the first pit and the surface of the first substrate through photolithography and etching , the first attracting electrode and the conversion conductor. Cr/Au with a certain thickness is sputtered on the back of the first substrate to form a ground line in the first microstrip line. Then a sacrificial layer is filled in the first pit, and the material of the sacrificial layer is positive photoresist. The sacrificial layer is planarized using a chemical mechanical polishing process (CMP) so that its surface is parallel to the quartz surface. Then deposit the first layer of compressive stress silicon nitride, the Cr/Au of the driving conductive layer and the second layer of compressive stress silicon nitride on the surface of the sacrificial layer and the quartz surface in sequence, and the compressive stress in the film is not greater than 100MPa. Then dry etch the second layer of silicon nitride, the middle Cr/Au layer and the first layer of silicon nitride in sequence to form a second dielectric film, a driving conductive film, a warped elastic dielectric film and sacrificial layer etching holes. The photoresist of the sacrificial layer is etched through the etching hole of the sacrificial layer to release the warped elastic dielectric film. Then etch the second pit on the second substrate, sputter Cr/Au with a certain thickness, and form the signal line of the second microstrip line and the second microstrip line on the second pit and the surface of the second substrate through photolithography and etching. Attract the electrodes. A certain thickness of Cr/Au is sputtered on the back of the second substrate to form a ground line in the second microstrip line. The two substrates and the components on them are aligned and bonded by bonding to form the cavity of the switch part and the switch.

According to the effect of the foregoing invention, the switch has a state latch function and has no static power consumption.

Claims (9)

1. A single pole double throw radio frequency and microwave micromechanical switch, it is characterized in that the switch consists of a first recess (214) on the first substrate (201), a first waveguide positioned at the bottom of the first recess and the surface of the first substrate line, the first attracting electrode at the bottom of the first recess, the conversion conductor on the surface of the first substrate, the second recess (213) on the second substrate (210), the second electrode at the bottom of the second recess and the second substrate surface. The waveguide, the second attracting electrode at the bottom of the second recess, the warped elastic dielectric film (205) suspended between the first recess and the second recess, the driving conductive film (208) on the warped elastic dielectric film and the The second dielectric film (209) is composed of a second dielectric film (209), and prestress exists in the warped elastic dielectric film. 2. The SPDT radio frequency and microwave micromechanical switch according to claim 1, wherein the first waveguide and the second waveguide are coplanar waveguide structures or microstrip line structures. 3. The SPDT radio frequency and microwave micromechanical switch according to claim 1, characterized in that the warped elastic dielectric film is in the first locked state, that is, bent toward the first substrate, and the middle part of the lower surface of the elastic dielectric film is in contact with The signal lines in the first waveguide are in contact; or the warped elastic dielectric film can be in the second locked state, that is, bent toward the second substrate, and the middle part of the upper surface of the second dielectric film is in contact with the signal line in the second waveguide touch. 4. SPDT radio frequency and microwave micromechanical switch according to claim 1 is characterized in that the precompression stress that exists in the warp elastic dielectric film, the critical stress of precompression stress is ${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; cr</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; E.</span>}{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 3</span>}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}$ Among them, σ _cr is the critical stress, E is the Young's modulus of the material constituting the film, t is the film thickness, α is the length of the rectangular dielectric film, v is Poisson's ratio, and the critical stress is the compressive stress not greater than 100MPa. 5. SPDT radio frequency and microwave micromechanical switch according to claim 1, is characterized in that the depth of the first recess or the second recess is not less than 1 micron, is not more than 5 microns simultaneously; Simultaneously, the depth of the first recess and The difference in depth of the second recesses is not greater than 0.2 microns. 6. The single pole double throw radio frequency and microwave micromechanical switch according to claim 1, characterized in that the transition conductor is used to connect the second waveguide. 7. The single pole double throw radio frequency and microwave micromechanical switch according to claim 1 or 4, wherein the warp elastic dielectric film is a geometric shape of a three-layer composite film, and the first layer is compressive stress silicon nitride, Cr/Au Drive conductive layer and second layer of compressively stressed silicon nitride. 8. The single pole double throw radio frequency and microwave micromechanical switch according to claim 1, characterized in that the driving conductive film is electrically insulated from both the first waveguide and the second waveguide. 9. A method for making a single-pole double-throw radio frequency and microwave micromechanical switch with a state latch function, characterized in that the making of a coplanar waveguide structure specifically includes the following steps: (1) forming a first recess on the first substrate; (2) forming a first waveguide, a first attracting electrode, and a conversion conductor on the bottom of the first recess and the surface of the first substrate; (3) forming a second recess on the second substrate; (4) forming a second waveguide and a second attracting electrode at the bottom of the second recess and the surface of the second substrate; (5) filling the sacrificial layer material in the first recess; (6) Planarize the material of the sacrificial layer so that its upper surface is parallel to the upper surface of the first substrate, and the height difference between the two is not less than 0.1 micron and not greater than 0.5 micron; (7) forming an elastic medium layer on the first substrate and the sacrificial layer in the first recess, wherein there is a prestress, which is a compressive stress not greater than 100 MPa; (8) forming a conductive layer on the above-mentioned elastic medium layer; (9) forming a second dielectric layer on the above-mentioned conductive layer; (10) etching the second dielectric layer to form a second dielectric film; (11) Etching the conductive layer and the elastic dielectric layer to form an elastic dielectric film, a driving conductive film and a sacrificial corrosion hole; (12) Erosion removes the sacrificial layer, releases and forms a warped elastic dielectric film; (13) The upper surface of the first substrate and the lower surface of the second substrate are bonded to each other, the aforementioned first recess is aligned with the second recess to form a switch cavity, and the second waveguide and the second attracting electrode are aligned with the conversion conductor , forming a conversion.

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