CN102064042A

CN102064042A - Normally open state field emission type radio frequency micro-mechanical switch

Info

Publication number: CN102064042A
Application number: CN2010105912405A
Authority: CN
Inventors: 黄庆安; 王立峰; 唐洁影; 韩磊; 张晓兵
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2010-12-16
Filing date: 2010-12-16
Publication date: 2011-05-18
Anticipated expiration: 2030-12-16
Also published as: CN102064042B

Abstract

The invention discloses a normally open state field emission type radio frequency micro-mechanical switch, comprising a low loss substrate, an insulating medium film, a coplanar waveguide signal wire and earth wires, wherein the signal wire is located between two earth wires; the insulating medium film is arranged among a low loss substrate signal wire and the earth wires; a row of metal micro tips are respectively arranged at the left side and the right side in the middle of the signal wire, and a row of metal micro tips are respectively and correspondingly arranged in the middle of the adjacent sides of the two earth wires and the signal wire; gaps are reserved between the metal micro tips on the earth wires and the metal micro tips on the adjacent signal line; and the position of the low loss substrate corresponding to the metal micro tips is recessed to form two hollow cavities so that the metal micro tips are in a suspending state. Because the similar mechanical switches are physically switched off by a coplanar waveguide signal wire structure, the micro-mechanical switch has high isolation degree; because the on-off mode without a movable structure is similar to a semiconductor switch, the micro-mechanical switch has high reliability and quick response speed; and a lower switch threshold voltage can be obtained through utilizing a top-to-tip structure.

Description

A kind of normal ON state field emission type rf micromechanical switch

Technical field

The present invention relates to a kind of novel normal ON state field emission type rf micromechanical switch.

Background technology

There are the following problems for existing radio-frequency (RF) switch:

(1) some adopt the mechanical movement of structures to reach the purpose of control radiofrequency signal break-make, and from physically cutting off, so isolation is higher with radiofrequency signal for these switches.These switches can be divided into contact and condenser type two big classes again, the reliability of touch switch is by the contact damage of structure and the fatigue properties decision of material, the reliability of capacitance-type switch is then determined by the electric charge injection effect of dielectric layer and the fatigue properties of material, so the reliability of these two kinds of switches is all undesirable.And, make that the response time of these switches is longer owing to adopted the mode of mechanical movement.

(2) some then adopt semiconductor PIN structure to control the break-make of radiofrequency signal, and integrity problem and long defective of response time that these switches have avoided mechanical movement to bring have high reliability and fast-response speed.The defective of this method mainly is: thorough inadequately when adopting semiconductor PIN structure to the isolation of radiofrequency signal, so isolation is not high.

Summary of the invention

For solving the problems of the technologies described above, the invention provides a kind of high-isolation, high reliability, fast-response speed and the low normal ON state field emission type rf micromechanical switch of carrying out voltage.

The present invention includes low loss substrate, the holding wire of dielectric film, co-planar waveguide and ground wire, holding wire is between two ground wires, the dielectric film is located between low loss substrate holding wire and the ground wire, holding wire middle part each side be provided with the little point of row's metal, the middle part of corresponding two adjacent sides with holding wire of ground wire also respectively is provided with the little point of row's metal, has between the little point of metal on little point of the metal on the ground wire and the adjacent signals line at interval; Low loss substrate and the corresponding position of the little point of above-mentioned metal indent form two cavitys, make the little point of metal be vacant state.The equal indentation of the little point of above-mentioned metal, and be the one-to-one relationship of tip to tip between the little point of adjacent metal, can reach the effect that reduces threshold voltage like this.

The present invention utilizes the little point of metal that the principle of field emission can take place under certain field intensity, produce electronic beam current between the little point of two row's metals, make the switch that is in ON state originally radiofrequency signal is shorted to ground wire, promptly reached the effect of control radiofrequency signal break-make by electronic beam current.

The present invention combines the advantage of mechanical switch and semiconductor switch, promptly adopts the signal line structure of the co-planar waveguide that physically cuts off and does not have the break-make mode of movable structure, and the effect of high reliability and fast-response speed is arranged again when reaching existing high-isolation.

Description of drawings

Fig. 1 is a structural representation of the present invention.

Fig. 2 is the A-A cutaway view of Fig. 1.

Specific embodiments

As depicted in figs. 1 and 2, the present invention includes low loss substrate 1, the holding wire 5 of dielectric film 2, co-planar waveguide and ground wire 3, holding wire is between two ground wires, dielectric film 2 is located between low loss substrate 1 holding wire and the ground wire, holding wire middle part each side to be provided with row's metal little sharp 4, it is little sharp 4 that the middle part of corresponding two adjacent sides with holding wire of ground wire also respectively is provided with row's metal, and the interval is arranged between the metal little sharp 4 on metal on the ground wire little sharp 4 and the adjacent signals line; Low loss substrate 1 forms two cavitys 6 with the little sharp 4 corresponding position indents of above-mentioned metal, makes metal little sharp 4 be vacant state.Above-mentioned metal little sharp 4 equal indentations, and be the one-to-one relationship of tip to tip between the little point of adjacent metal.

Manufacture method of the present invention is:

Growth one deck dielectric film 2 on low loss substrate 1 at first carries out photoetching for the first time and etching dielectric film and forms the required window of corrosion cavity 6.Carry out the photoetching second time, then splash-proofing sputtering metal and peel off holding wire 5, ground wire 3 and the metal little sharp 4 that forms co-planar waveguide.Low loss substrate is carried out anisotropic etch, obtain cavity 6, make that metal little sharp 4 is unsettled.

Operation principle of the present invention is:

Apply the electric field of certain intensity to the metal surface after, electric field can quicken the metal surface electronics.When the energy that quicken to obtain by electric field when the metal surface electronics exceeded the work function of this metal, the electronics of metal surface will escape from metal, and moves along direction of an electric field, formation field emitted electron line.Field emission makes the metal of originally keeping apart by the electronic beam current conducting, forms impedance much smaller when isolating, and this little impedance can be shorted to the radiofrequency signal of script conducting ground wire, is about to radiofrequency signal and turn-offs.

The course of work of the present invention is as follows:

Radiofrequency signal is connected to the port of co-planar waveguide, adds dc offset voltage at co-planar waveguide holding wire and ground wire two ends simultaneously.When dc offset voltage was zero, switch was in conducting state, the radiofrequency signal conducting; After adding, dc offset voltage surpassed the threshold voltage of field emission, switch was in the pass off-state, and radiofrequency signal is turn-offed.

Using method of the present invention is: radiofrequency signal is connected to the port of co-planar waveguide, adds dc offset voltage at the two ends of co-planar waveguide holding wire and ground wire simultaneously.Come the break-make of radiofrequency signal on the control switch with the added dc offset voltage of co-planar waveguide holding wire and ground wire two ends.

Claims

1. normal ON state field emission type rf micromechanical switch, it is characterized in that comprising low loss substrate (1), dielectric film (2), holding wire of co-planar waveguide (5) and ground wire (3), holding wire is between two ground wires, dielectric film (2) is located between low loss substrate (1) holding wire and the ground wire, what it is characterized in that holding wire middle part each side is provided with row's little point of metal (4), accordingly, the middle part of two adjacent sides with holding wire of ground wire also respectively is provided with row's little point of metal (4), has between the little point of metal (4) on little point of the metal on the ground wire (4) and the adjacent signals line at interval; Low loss substrate (1) forms one two cavitys (6) with the corresponding position of the little point of above-mentioned metal (4) indent, makes the little point of metal (4) be vacant state.

2. normal ON state field emission type rf micromechanical switch as claimed in claim 1 is characterized in that all indentations of the little point of metal (4), and is the one-to-one relationship of tip to tip between the little point of adjacent metal.