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CN1942986A - Electromechanical switch - Google Patents

Electromechanical switch Download PDF

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Publication number
CN1942986A
CN1942986A CN 200680000113 CN200680000113A CN1942986A CN 1942986 A CN1942986 A CN 1942986A CN 200680000113 CN200680000113 CN 200680000113 CN 200680000113 A CN200680000113 A CN 200680000113A CN 1942986 A CN1942986 A CN 1942986A
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CN
China
Prior art keywords
mechanical switch
electric mechanical
movable electrode
electrode
displacement
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CN 200680000113
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Chinese (zh)
Inventor
中西淑人
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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Publication of CN1942986A publication Critical patent/CN1942986A/en
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Abstract

There is provided an electro-mechanical switch capable of performing high-speed switching response with a low drive voltage. An electro-mechanical switch main body (10) which is a MEMS switch includes a first movable electrode (14) and a second movable electrode (16) having both ends fixed and bridged by a first anchor (12) and a second anchor (13) formed on a silicon substrate (2) and a fixed electrode (18) opposing to these movable electrodes. The first movable electrode (14) having a relatively weak spring force and the fixed electrode (18) constitute a first electro-mechanical switch (22) which can be driven with a low voltage. The second movable electrode (16) having a relatively strong spring force and the fixed electrode (18) constitute a second electro-mechanical switch (24) which can be driven and latched with a low voltage. The first movable electrode (14) is rapidly displaced by a low drive voltage to rapidly turn on the first electro-mechanical switch and the second movable electrode (16) rapidly performs natural oscillation by the restoration force to rapidly turn off the second electro-mechanical switch. The returning second movable electrode (16) is latched with low drive voltage and the second electro-mechanical switch is turned on.

Description

Electric mechanical switch
Technical field
The present invention relates to a kind of micro electro-mechanical system switch (" MEMS " switch hereinafter referred to as), more specifically, relate to a kind of electric mechanical switch with low driving voltage.
Background technology
Such as HEMT switch, MESFET switch with adopt the RF switch (radio frequency and microwave switch) of the pin diode switch of GaAs substrate to become the main flow of RF switch at present.
But for the more high-performance and the more low-power consumption that realize wireless terminal, the someone proposes to utilize the device that also adopts microcomputer electric component except conventional semiconductor element.
This device is a kind ofly to be suitable for being used for driving microelectrode by electrostatic force etc., and the relative distance between the electrode is carried out machinery control, and carries out the electric mechanical switch that switches on and off operation of signal thus.When connecting, electrode electrically contacts mutually.Therefore, the loss between the electrode is minimum, thereby can realize low loss switching.
Especially, the RF switch that is installed in the fore-end of wireless terminal requires low-loss and low energy consumption.Expect that the device of this employing microcomputer electric component is a kind of useful solution.
People have designed the switch of the conventional electromechanical compo of various employings.Non-patent literature 1 has covered this type of switch of great majority.
For example, the employing RFMEMS (radio-frequency micro electromechanical system) that describes in the non-patent literature 1 is made of movable electrode and fixed electrode.When the dc voltage that between movable electrode and fixed electrode, applies as drive control voltage, produce electrostatic force.Adopt described electrostatic force as actuating force with movable electrode to the fixed electrode tractive.The physics contact takes place in electrode mutually.Be output to fixed electrode side lead-out terminal from the input signal of movable electrode side input terminal input, thereby make signal obtain coupling.
The method of coupled signal comprises method that metal and metal are directly contacted and the method that makes the metal capacitance coupling by insulator.Two kinds of methods all can realize the low-loss coupling.
Change at 0 o'clock in the drive control voltage that will put between the electrode, electrostatic force is cancelled.Movable electrode utilizes spring force to get back to original position as actuating force.
At this moment, the distance between movable electrode and the fixed electrode is fully big.Therefore, the capacitance between the electrode is little.Thereby do not produce capacitive coupling therebetween.Can shield the signal that will between electrode, be coupled.
Therefore, when distance between electrodes is fully big, can fully guarantee isolation therebetween.And loss is also minimum.Compare with adopting conventional semi-conductive RF switch, this switch has remarkable electrical characteristics.
And patent documentation 1 has proposed such mems switch.
The purpose of the mems switch of describing in the patent documentation 1 is to reduce the response time and reduction applies voltage.This switch has with far away slightly spaced first, second and the 3rd beam, and the voltage bringing device that is suitable for applying to described beam electrostatic force.This switch is configured to change the position of each beam and the electric capacity between the beam by electrostatic force.The two all can move first beam and second beam, makes that beam can be to be electrically coupled to together at a high speed.And, in order to make beam, making generating electrostatic force in the face of on the 3rd beam of second beam with high-speed transitions direction (put off), described the 3rd beam is initial to be placed near first beam and second beam.Therefore, can between second beam and the 3rd beam, apply strong electrostatic force.Therefore, this switch has been realized response more at a high speed.
In addition, in each beam, provide same flexure moulding part.The variation that this can relax with corresponding the drawing in of variation (pull-in) voltage of the internal stress of beam also can relax the change to beam electric capacity of the beam that caused by the beam strain.
Non-patent literature 1:Gabriel M.Rebeiz, " RF MEMS THEORY, DESIGN, ANDTECHNOLOGY ", John Wiley ﹠amp; Sons, February 1,2003, p.122.
Patent documentation 1:JP-A-2004-111360 (the 5th page and the 6th page, accompanying drawing 1 and 3 to 3).
Summary of the invention
Technical problem to be solved by this invention
But the MEMS that describes in the non-patent literature 1 requires strong electrostatic force, because will utilize electrostatic force to move the movable electrode with limited quality as actuating force.And, described mems switch has such problem: be switched on or switched off the required response time of mems switch more than or equal to tens μ s, its with adopt conventional semiconductor element to be switched on or switched off the required response time that is in nanosecond (ns) magnitude of switch to compare extremely long.
For example, the non-patent literature of having delivered 1 has been summed up the driving voltage and the response time of each electric mechanical switch.The minimum response time is 4 μ s.
But, on it, apply 40V or higher very high voltage (non-patent literature 1, p.16).
Mems switch is being used under the situation of wireless communication terminal, the restriction driving voltage makes mems switch work under several volts or lower voltage.In addition, mems switch is being applied under the situation of some wireless system, for example, with regard to some Wireless LAN systems, is requiring mems switch to be switched on or switched off in the short time at the utmost point of 0.2 μ s.With regard to the example that non-patent literature 1 is described, the required response time is about 4 μ s.
This be because, although except the restriction of driving voltage of restriction wireless communication system, be necessary between electrode, to be provided with big value distance to guarantee the expection isolation, when distance betwixt was big, the response time must be grown.
And, when its fixed electrode is drawn in the movable electrode of mems switch, adopt electrostatic force.But,, adopt the spring force of movable electrode when it draws back described movable electrode.Connect required response time and the required response time equilibrium of cut-off switch of switch in order to make, the value of spring force that must movable electrode is set to be higher than the value of a certain value.Play in raising under the situation of spring force of actuating force effect,, therefore, need higher driving voltage inevitably owing to, should apply the electrostatic force of this spring force of opposing when fixed electrode is drawn in movable electrode.
Therefore, there is the high problem of driving voltage in the mems switch of describing in the non-patent literature 1.
And patent documentation 1 described example makes that through revising all beams all are movable, realizes switching at a high speed thus, and realizes the operation under the low DC electromotive force.But, switch carrying out high speed, and it is more and more to have a requirement of the switch of low driving voltage more.
The present invention realizes under the condition of considering above-mentioned situation.The object of the present invention is to provide a kind of electric mechanical switch that can realize under low driving voltage that high speed is switched.
The scheme of technical solution problem
In order to achieve the above object, a kind of electric mechanical switch according to the present invention comprises mems switch, described mems switch comprises: first electric mechanical switch, it is suitable for switching on and off according to the displacement of at least the first beam, described first beam is to reply by weak relatively spring force, in addition, also comprises second electric mechanical switch, it is suitable for switching on and off according to the displacement of at least the second beam, and described second beam is to reply by strong relatively spring force.Under initial condition, described first electric mechanical switch disconnects, and described second electric mechanical switch is connected, and with this understanding, described electric mechanical switch is in off-state.
Rely on this structure, first electric mechanical switch is to connect at a high speed.And described second electric mechanical switch is to disconnect at a high speed.So, a kind of electric mechanical switch can be provided, it can obtain driving under low-voltage, and to carry out handoff response at a high speed.
In addition, this electric mechanical switch is carried out mechanical handover operation, thereby guarantees high degree of isolation with low-loss.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, applying and cancel one of operation by actuating force, described first beam is subjected to displacement by initial condition, and, wherein, described first electric mechanical switch is connected in response to the displacement of described first electric mechanical switch, makes described electric mechanical switch enter on-state thus.
Rely on this structure, can be with the turn-on response of realization of High Speed to the machinery switching.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, under described first electric mechanical switch and the two situation about all connecting of described second electric mechanical switch, cancel the displacement of described first beam and the displacement of described second beam simultaneously, reply operation to carry out, thereby disconnect second electric mechanical switch, make described electric mechanical switch enter off-state thus.
Rely on this structure, can respond the disconnection that machinery switches with realization of High Speed.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, by disconnecting described second electric mechanical switch, described second beam begins to carry out intrinsic vibration; And, wherein, when described second beam turns back to described second electric mechanical switch and disconnects its residing displaced position near situation under, applying and cancel described second beam of one of operation locking by actuating force.
Rely on this structure, can lock second electric mechanical switch by carrying out low voltage operating.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on electrostatic force.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on electromagnetic force.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on piezoelectric effect.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on thermal expansion.
Rely on this structure, can beam is subjected to displacement by carrying out low voltage operating.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, it also comprises public fixed electrode, parallel surface is right with it by the space for described first beam and described second beam, and it is adapted such that by comprising fixed electrode and first beam construction, first electric mechanical switch, by comprising fixed electrode and second beam construction, second electric mechanical switch.
Rely on this structure, can be adjusted to and carry out the different value of speed that second beam is electrically connected to the operation of fixed electrode carrying out the speed that first beam is electrically connected to the operation of fixed electrode.Thereby, realized the dpdt double-pole double-throw (DPDT) switching.
In addition, also comprise a kind of electric mechanical switch, wherein, be provided to the space of fixed electrode according to the amplitude peak of described first beam and the every person's of described second beam intrinsic vibration according to electric mechanical switch of the present invention.
Rely on this structure, the service speed of first electric mechanical switch can be made as the value different with second electric mechanical switch.Guaranteed isolation thus.
In addition, also comprise a kind of electric mechanical switch, have only when first electric mechanical switch and connect and second electric mechanical switch when also connecting that described electric mechanical switch just is in on-state according to electric mechanical switch of the present invention.
Rely on this structure, only first beam from initial condition when being subjected to displacement at a high speed, connect first electric mechanical switch, could connect described electric mechanical switch.Therefore, can realize the high speed turn-on response.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, described electric mechanical switch is through revising, make described first beam and described second beam layout that is parallel to each other, arrange the 3rd beam with described first beam and the described second Liangping row, described the 3rd beam can be replied by the spring force that is weaker than described second beam relatively, by comprising first beam and second beam construction, first electric mechanical switch, by comprising second beam and the 3rd beam construction second electric mechanical switch.
Rely on this structure, second beam of second electric mechanical switch is to be subjected to displacement at a high speed.Therefore, can be to carry out the on/off operation at a high speed.
In addition, also comprise a kind of electric mechanical switch, wherein, form space between described second beam and described first beam and the every person of described the 3rd beam according to the amplitude peak of the intrinsic vibration of described second beam according to electric mechanical switch of the present invention.
Rely on this structure, can realize high-speed response by the natural frequency that second beam is set.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, by constructing described electric mechanical switch, makes the displacement of the 3rd beam based on electrostatic force.
Rely on this structure, can the 3rd beam is subjected to displacement by carrying out low voltage operating.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, by constructing described electric mechanical switch, makes the displacement of the 3rd beam based on electromagnetic force.
Rely on this structure, except above-mentioned advantage, the present invention also has the advantage that the linear change that does not rely on displaced position (or slit) can be provided.This is because because electromagnetic force do not rely on distance, and with regard to the variation that electrostatic force causes, described slit only has about (1/3) produce linear change under the influence of drawing in phenomenon.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, by constructing described electric mechanical switch, makes the displacement of the 3rd beam based on piezoelectric effect.
Rely on this structure, except above-mentioned advantage, the present invention also has the advantage that promotes bidirectional displacement.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, by constructing described electric mechanical switch, makes the displacement of the 3rd beam based on thermal expansion.
Rely on this structure, except above-mentioned advantage, the present invention also has the advantage that can guarantee stronger contact force.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, and wherein, described beam comprises one of piezoelectric element, marmem, bimorph cell and electromagnetism distortion element, and perhaps wherein, a plurality of beams comprise these combination of elements.
Rely on this structure, the every person of described beam is with low-power operation.Therefore, can reduce operating voltage.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, by structure to described electric mechanical switch, make under the situation that displacement at described first beam, described second beam and described the 3rd beam all is cancelled, make described second beam more near in described the 3rd beam by mechanical probe, by the applying and cancel one of operation described the 3rd beam is subjected to displacement of actuating force, lock described second beam thus.
Rely on this structure, described second beam is subjected to displacement, and more near the 3rd beam.Therefore, can under low-power, operate the 3rd beam.
In addition, also comprise a kind of electric mechanical switch, wherein, place air pressure to be different from the environment of atmospheric pressure described first electric mechanical switch and described second electric mechanical switch or filled the environment of dried helium according to electric mechanical switch of the present invention.
Rely on this structure, reduced the influence to the beam of high speed operation such as air.Therefore, can reduce damping effect.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, wherein, described second electric mechanical switch only disconnects described first electric mechanical switch and obtains the required time of predetermined isolated.
Rely on this structure, can guarantee high degree of isolation.And, can also guarantee to realize opening operation.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, by the modification to described electric mechanical switch, makes cycle of intrinsic vibration of described second beam equal described first beam and reaches described first beam and obtain the enough isolation required time of residing position.
In addition, electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, by modification to described electric mechanical switch, make and connect at described first electric mechanical switch, and with signal condition by switching to by state under the situation of masked state, described second beam reaches described second beam and obtains the necessary residing position that isolates, and arrives described first beam up to described first beam and obtains the predetermined isolated desired position, and described second beam is then got back to initial lock-out state once more.
Rely on this structure, guaranteed isolation with second beam of high speed operation.And, guaranteed isolation with first beam of low relatively speed operation after, can lock second beam.
In addition, also comprise a kind of electric mechanical switch according to electric mechanical switch of the present invention, it also comprises the first low spring movable electrode, the taller springs movable electrode and the second low spring movable electrode, they are arranged in parallel, make the low spring movable electrode of winning comprise first beam, the taller springs movable electrode comprises second beam, the second low spring movable electrode comprises the 3rd beam, first electric mechanical switch has the first low spring movable electrode that comprises first beam, also has first fixed electrode of arranging in the face of first beam, the 3rd electric mechanical switch has the second low spring movable electrode that comprises the 3rd beam, also has the 3rd fixed electrode of arranging in the face of second beam, second electric mechanical switch has the taller springs movable electrode that comprises second beam, also have from first fixed electrode and extend with first area in the face of the taller springs movable electrode, and extend with the second area in the face of the taller springs movable electrode from second fixed electrode, first beam and second beam are by the mutual mechanical connection in coupling part.
And electric mechanical switch of the present invention also comprises a kind of electric mechanical switch, and the modification through to described electric mechanical switch makes described second beam be connected to input terminal, and described first beam and described second beam are connected to first lead-out terminal and second lead-out terminal respectively.
Rely on these structures, the 3rd beam responds first beam and the every person's of second beam displacement and is subjected to displacement.Therefore, even under the first low influence of spring movable electrode and under by the situation of first fixed electrode locking in certain fault, the present invention can prevent from also to produce that the taller springs movable electrode with strong spring power can not be drawn into and the state that finally mediates, that is, the first and second low spring movable electrodes and taller springs movable electrode all are in the state of off-state.
Advantage of the present invention
In electric mechanical switch according to the present invention, connect first electric mechanical switch at a high speed, described first electric mechanical switch can be worked by low voltage drive.To close second electric mechanical switch at a high speed, described second electric mechanical switch can be locked under low-voltage.Therefore, the present invention has following advantage: electric mechanical switch can be worked under low driving voltage, and switches on and off according to the combining of high speed of first electric mechanical switch and second electric mechanical switch.
Description of drawings
Fig. 1 is the external view of explanation according to the structure of the unit element of the electric mechanical switch of first embodiment.
Fig. 2 is the partial cross section view of structure of explanation first electric mechanical switch of first embodiment and the every person's of second electric mechanical switch essential part.
Fig. 3 is the cross-sectional view that the A-A line along Fig. 2 obtains.
Fig. 4 is the circuit diagram of explanation according to the equivalent electric circuit of electric mechanical switch of the present invention.
Fig. 5 is that the longitudinal axis is represented the position of first movable electrode with respect to fixed electrode, the curve chart of transverse axis express time.
Fig. 6 be explanation under the situation that the position drive control voltage that first movable electrode and fixed electrode are in contact with one another is set to disconnect, the curve chart of the transient response of the residing position of first movable electrode.
Fig. 7 is the curve chart of transient response of the residing position of second movable electrode of explanation second electric mechanical switch.
Fig. 8 be explanation shown in Fig. 7 of the transient response of explanation second movable electrode residing position corresponding to amplified curve figure smaller or equal to the behavior of time of 1 μ s.
Fig. 9 be explanation according to the on-state of the electric mechanical switch of first embodiment and the diagram of off-state, it comprises (a) that off-state and on-state are described respectively and (b), every kind of state is all represented with equivalent electric circuit.
Figure 10 is the curve chart of transient response of the residing position of movable electrode of the transient response of the residing position of movable electrode of explanation first electric mechanical switch and second electric mechanical switch.
Figure 11 is the state diagram of inscribing first electric mechanical switch and second electric mechanical switch when with equivalent electric circuit each being described, it comprise illustrate corresponding to constantly 0 respectively, the state (a) and (b) of t1, t2 and t3, (c) and (d).
Figure 12 is the diagram of the structure of each parallel-plate-type electrode of explanation and comb tooth (pectinate) type electrode.
Figure 13 is the schematic diagram of electric mechanical switch, in described electric mechanical switch, and the operation of movable electrode along continuous straight runs.
Figure 14 is the external view of silicon substrate, forms the unit elements of electric mechanical switch in described silicon substrate.
Figure 15 is the external view of seal cover glass.
Figure 16 is the cross-sectional view that obtains along B-B line shown in Figure 14, and it has illustrated each step according to the electric mechanical switch manufacturing process of first embodiment.
Figure 17 is the schematic diagram of structure of the example of explanation second embodiment.
Figure 18 is the curve chart of the displacement of second movable electrode among explanation second embodiment.
Figure 19 is the schematic diagram of explanation according to the electric mechanical switch of the 3rd embodiment.
Figure 20 is the key-drawing of the operation of explanation the 3rd embodiment.
Figure 21 is the key-drawing of the operation of explanation the 3rd embodiment.
Description of reference numerals
1,40,70,200 electric mechanical switchs
2 silicon substrates
3 seal cover glass
4,211 first electrode terminals
5,212 second electrode terminals
6,213 third electrode terminals
7,214 the 4th electrode terminals
8,215 the 5th electrode terminals
9,216 the 6th electrode terminals
10 electric mechanical switch main bodys
12,72,201 first anchors
13,73,203 second anchors
14,74,202 first movable electrodes
16,76,204 second movable electrodes
18,62,66,78 fixed electrodes
22 first electric mechanical switchs
24 second electric mechanical switchs
31,32 curves
60 parallel-plate-types
64,68 movable electrodes
69 comb flute profiles
82 first concave portions
84 second concave portions
86 the 3rd concave portions
88 the 4th concave portions
92,94,96 ledges
102 sacrifice layers
104 resist layers
206 second movable electrodes
Embodiment
Will electric mechanical switch according to the present invention be placed under the pressure of reduction or under the helium atmosphere as environment, wherein weakened the damping effect of the viscosity of air etc.Electric mechanical switch according to the present invention is made of first electric mechanical switch and second electric mechanical switch, in first electric mechanical switch, draw in towards fixed electrode with the movable electrode that will have weak spring power at a high speed, in second electric mechanical switch, the movable electrode that will have strong spring power is pulled away from fixed electrode.Under static state, can only be by being switched on or switched off the first electric mechanical switch switching signal.
In addition, in order to obtain enough isolation under the instantaneous state that first electric mechanical switch is produced when signal is subjected to shielding, first electric mechanical switch will guarantee that being drawn back enough distances at electrode sets up isolation in the used time.By guaranteeing isolation under the instantaneous state to make at a high speed second electric mechanical switch enter off-state.
And, make by modification to second electric mechanical switch, although only just drawn back movable electrode in moment,, under the effect of strong spring power and underdamping effect, movable electrode produces intrinsic vibration, and movable electrode is got back near the original position.Therefore, can under small voltage, lock second electric mechanical switch that (latch) has strong spring power.
Therefore, as adopting can being implemented under the low driving voltage with high speed on/off signal by first electric mechanical switch is combined with second electric mechanical switch of microcomputer electric component according to electric mechanical switch of the present invention, described first electric mechanical switch adopts the electrode with weak spring power, and drawn in high speed, reset with low speed, second electric mechanical switch adopts the electrode with strong spring power, and it is released from latch (latch), and is locked immediately.
Hereinafter, with the preferred embodiment of describing in detail according to electric mechanical switch of the present invention.In the accompanying drawings, use the same reference numerals to represent basic identical or corresponding parts.
(first embodiment)
Fig. 1 is the external view of explanation according to the structure of the unit element of the electric mechanical switch of first embodiment.
Fig. 2 is the partial cross section view of structure of explanation first electric mechanical switch of first embodiment and the every person's of second electric mechanical switch essential part.
As depicted in figs. 1 and 2, electric mechanical switch 1 according to first embodiment has the electric mechanical switch main body 10 that is formed at also sealed cover glass 3 coverings on the silicon substrate 2, has first electrode terminal 4, second electrode terminal 5, third electrode terminal 6, the 4th electrode terminal 7, the 5th electrode terminal 8 and the 6th electrode terminal 9 that play the input/output terminal effect in addition.
As shown in Figure 2, electric mechanical switch main body 10 has first movable electrode 14 and second movable electrode 16, the two ends of each movable electrode are all placed and are fixed on first anchor 12 and second anchor 13 that is formed on the silicon substrate 2, and electric mechanical switch main body 10 also has crosses over the fixed electrode 18 of pre-fixed gap in the face of first movable electrode 14 and 16 formation of second movable electrode.
In first embodiment, first movable electrode 14 and second movable electrode 16 all are configured at plate (inboard) beam.First movable electrode 14 and second movable electrode 16 are configured to, and first movable electrode 14 has weak relatively spring force, and second movable electrode 16 has strong relatively spring force (springforce).
First electric mechanical switch 22 is configured to comprise first movable electrode 14 and fixed electrode 18.Second electric mechanical switch 24 is configured to comprise second movable electrode 16 and fixed electrode 18.These electric mechanical switchs are one another in series.
First movable electrode 14 and second movable electrode 16 adopt according to the electrostatic force of applied voltage generation and the spring force of these movable electrodes self and carry out intrinsic vibration.Guarantee the space of size more than or equal to the amplitude peak of intrinsic vibration.
In order to reduce damping effect, fill this space with dried helium.Perhaps, make described space keep vacuum.
Incidentally, the input/output terminal of first movable electrode 14 is first electrode terminal 4 and the 5th electrode terminal 8.The input/output terminal of second movable electrode 16 is second electrode terminal 5 and the 4th electrode terminal 7.The input/output terminal of fixed electrode 18 is third electrode terminal 6 and the 6th electrode terminal 9.
For example, adopting under the situation of the 5th electrode terminal 8 as signal input terminal, second electrode terminal 5 and the 4th electrode terminal 7 are signal output terminal.
In addition, the control voltage source that is used for applying electrostatic force between fixed electrode and first movable electrode 14 and second movable electrode, 16 every persons can be connected to each electrode terminal.
Fig. 3 is the cross-sectional view that the A-A line along Fig. 2 obtains.
As shown in Figures 2 and 3, the length L 1 of first movable electrode 14 and second movable electrode 16 and L2 (not shown) are set to the equal length L of 400 μ m.Width w1 and w2 are set to 2.5 μ m and 5 μ m respectively.Thickness D1 and D2 are the same thickness of 0.4 μ m.Slit g2 between slit g1 between fixed electrode 18 and the electrode 14 and fixed electrode 18 and the electrode 16 is set to 0.2 μ m and 1.5 μ m respectively.
Fig. 4 is the circuit diagram of explanation according to the equivalent electric circuit of electric mechanical switch of the present invention.
As shown in Figure 4, electric mechanical switch 40 according to the present invention has first electric mechanical switch 22 and second electric mechanical switch 24.Under initial condition, first electric mechanical switch 22 is in off-state, and second electric mechanical switch 24 is in on-state.Under initial condition, electric mechanical switch 40 disconnects.
That is to say, under initial condition, apply drive control voltage to second movable electrode 16.Second movable electrode 16 is electrically connected to fixed electrode 18 by electrostatic force.But, do not apply drive control voltage to first movable electrode 14.
Next, will be described below operation according to the electric mechanical switch of first embodiment.
With reference to figure 2 and Fig. 4, when under initial condition when first movable electrode 14 applies drive control voltage, electrostatic force is drawn in towards fixed electrode 18 with first movable electrode, 14, the first movable electrodes 14 that high speed operation has spring force, and is electrically connected with it.Thus, make first electric mechanical switch 22 enter on-state, thereby connect electric mechanical switch 40.
When cancellation was applied to the drive control voltage of first movable electrode 14 and second movable electrode 16, the spring force of each movable electrode was pulled away from fixed electrode 18 with first movable electrode 14 and second movable electrode 16.At first, make second electric mechanical switch 24 enter off-state, thereby disconnect electric mechanical switch 40.
At this moment, second movable electrode 16 with strong spring restoring force is with the higher speed operation of speed than first movable electrode 14 with weak spring restoring force, and it breaks away from fixed electrode 18 and begins to carry out intrinsic vibration.
Second movable electrode 16 when this vibration revert to fixed electrode 16 near the time, under the situation that applies drive control voltage on it, by electrostatic force with second movable electrode 16 towards fixed electrode 18 locking.In this course, first movable electrode 15 is fully away from fixed electrode 18, and therefore first electric mechanical switch 22 is in off-state.Even when locking second movable electrode 16, electric mechanical switch 40 still keeps disconnecting, thereby second electric mechanical switch 24 is in on-state.
Therefore, the electric mechanical switch according to first embodiment can switch on and off response to carry out at a high speed according to first electric mechanical switch and the combination to enter second electric mechanical switch of off-state at a high speed to enter on-state at a high speed.
Next, the operation of electric mechanical switch under the situation that adopts the movable electrode of describing in the explanation of plate inner beam as first embodiment will be described in detail in hereinafter by way of example.
At movable electrode is under the situation about being made of the plate inner beam, with the same among first embodiment, by the spring constant k of equation (1) expression movable electrode.
k=Ew(D/L) 3+8σ(1-υ)w(D/L)…(1)
Incidentally, E represents Young's modulus, and w represents the live width of movable electrode.D represents the thickness of movable electrode.L represents the length of movable electrode, and σ represents internal stress, and υ represents Poisson's ratio.
Obviously can see by equation (1), can change spring constant k by shape, material and the physical property that changes movable electrode.
Next, provided the equation of motion under the situation that has applied from external force F to movable electrode by following equation (2).
md2Z(t)/dt2+b(1.2-Z(t)/g)-3/2Z(t)+kZ(t)=F…(2)
Incidentally, Z (t) expression movable electrode is in the position of moment t with respect to fixed electrode, and m represents the quality of movable electrode, and b represents damping coefficient, and g represents the initial value of distance between electrodes, and k represents the spring constant of movable electrode.
In first electric mechanical switch 22, the spring force of first movable electrode 14 extremely a little less than.First movable electrode 14 is designed to respond small actuating force.Therefore, when drawing in first movable electrode 14,, also can draw in first movable electrode 14 with the high-speed response actuating force even actuating force is very little.
For example, adopt aluminium (the little 50MPa of internal stress, Young's modulus is 70GPa, Poisson's ratio is 0.25, density is 2.69kg/m 3) as the material of first movable electrode 14, wherein, the data of representing its shape, be that width w1 is 2.5 μ m, thickness D is 0.4 μ m, and length L is 500 μ m, and the slit g1 between the electrode is under the situation of 0.2 μ m, when applying the voltage of 8V on it, first movable electrode is drawn in towards fixed electrode 18 in 0.2 μ s.
Fig. 5 is plotted as, and transverse axis express time, the longitudinal axis are represented by separating first movable electrode that the equation of motion (2) the obtains position with respect to fixed electrode.Therefore, Fig. 5 shows 0 constantly under the situation that applies driving voltage on it, the transient phenomenon of the change in location of first movable electrode.Be that the position that the fixed electrode 18 and first movable electrode 14 are in contact with one another is represented in this position under 0 the situation in the position of electrode.
As seen from Figure 5, first movable electrode 14 is drawn in towards fixed electrode 18 and contact with it in 0.2 μ s.
At this moment, make first movable electrode 14 that plays slim structure function during with the high speed executable operations, under the influence such as the fluid of surrounding air, it is complicated that described operation becomes.Therefore, the influence of fluid be can not ignore.
Therefore,, within switch, form enclosure space, in described enclosure space, form beam etc., make that the value of the damping effect that switch is interior is (1/25) of the damping effect of atmospheric air in order to alleviate this damping effect.
Next, will be described below the opening operation of first electric mechanical switch.
Obviously can see by equation (2), when disconnecting control voltage, adopt its spring force to make first movable electrode get back to original position as actuating force with the cancellation actuating force.But, because a little less than the described spring force, therefore, the response time is longer with regard to connecting switch.
Fig. 6 be explanation under the situation that the position drive control voltage that first movable electrode and fixed electrode are in contact with one another is set to disconnect, the curve chart of the transient response of the residing position of first movable electrode.
As shown in Figure 6, when the position that is in contact with one another at first movable electrode 14 and fixed electrode 18, when 0 constantly cancels electrostatic force, the spring force that adopts first movable electrode 14 makes first movable electrode 14 turn back to the original position of the value with 0.2 μ m in 1.6 μ s (about 2 μ s) as restoring force.Therefore, its proof is turning back to 10 times of response time of turning back to 0.2 required μ s of initial position under the situation that the there is making operation the required response time under the situation of opening operation.
Therefore, although only adopt first electric mechanical switch 22 just can realize the high speed making operation,, be difficult to realize the high speed opening operation.
Next, will be described below the structure and the operation thereof of second electric mechanical switch 24.
Construct second movable electrode 16 of second electric mechanical switch, make its spring force extremely strong.To form under the situation of second electric mechanical switch 24, advise increasing the slit g2 between the electrode with first electric mechanical switch, 22 identical shapes.Perhaps, suggestion is constructed described movable electrode according to equation (1), to improve spring constant.
For example, (internal stress is 50MPa, and Young's modulus is 70GPa, and Poisson's ratio is 0.25, and density is 2.69kg/m to adopt aluminium 3) as the material of second movable electrode.And, second movable electrode can be configured to have such shape, make that width w2 is 2.5 μ m, thickness D is 0.4 μ m, and length L is 500 μ m, and the slit g2 between the electrode is 1.5 μ m.
Fig. 7 and Fig. 8 show under the situation that does not apply external force (non-locking second movable electrode), when the canceling position control voltage that second movable electrode and fixed electrode are in contact with one another, and the transient response of the position of second movable electrode of second electric mechanical switch.Incidentally, Fig. 8 amplify shown shown in Figure 7 corresponding to behavior smaller or equal to time of 1 μ s.
Rely on this structure of second electric mechanical switch, the spring force of described second movable electrode is better than the spring force of first movable electrode of first electric mechanical switch.And the damping force of second movable electrode is weaker than the damping force of first movable electrode of first electric mechanical switch.Therefore, as shown in Figure 7, when second movable electrode was with natural frequency vibration, second movable electrode had changed the position from the position of fixed electrode.
As shown in Figure 8, in 0.2 μ s, the position of second movable electrode has arrived 0.16 μ m (about 0.2 μ m).In addition, as shown in Figure 7, second movable electrode has passed through the original position of 1.5 μ m in 1 μ s.Afterwards, this electrode and in 1.5 μ s, arrived the maximum displacement position of 3 μ m.Next, this electrode is got back in 2.5 μ s near the position corresponding to 0 displacement.
Therefore, set up the environment of the damping that suppresses second movable electrode.Therefore, the position of this electrode converges to the position corresponding to 1.5 μ m gradually.
Next, with the handover operation that is described in more detail below as the combination of first electric mechanical switch and second electric mechanical switch according to electric mechanical switch of the present invention.
At first, will be described below the operation that electric mechanical switch according to the present invention is become on-state from off-state.
Fig. 9 is the on-state of explanation electric mechanical switch and the diagram of off-state, and every kind of state all illustrates with equivalent electric circuit.
Shown in Fig. 9 (a), under the off-state according to electric mechanical switch of the present invention, first electric mechanical switch 22 is in off-state, and second electric mechanical switch 24 is in on-state.
That is to say, do not apply control voltage to first electric mechanical switch 22.Apply control voltage to second electric mechanical switch 24.Therefore, second movable electrode is locked to fixed electrode.
After being in first electric mechanical switch 22 under this state and applying drive control voltage, first movable electrode is drawn in towards fixed electrode.Afterwards, first movable electrode and fixed electrode are in contact with one another, and are electrically connected mutually.Thereby, shown in Fig. 9 (b), make electric mechanical switch be in on-state.At this moment, as mentioned above, in 0.2 μ s, draw in first movable electrode of first electric mechanical switch at a high speed.Therefore, signal has obtained transmission in 0.2 μ s.
As (a) of Fig. 9 with (b), second electric mechanical switch 24 remains the state that has applied drive control voltage on it, is about to first electric mechanical switch 22 and becomes on-state the instantaneous state of on-state from off-state.
Next, will be described below the operation that electric mechanical switch according to the present invention is become off-state from on-state.
Figure 10 shows the two the position of movable electrode of first electric mechanical switch and second electric mechanical switch.The position of the movable electrode of curve 31 expressions first electric mechanical switch.The position of the movable electrode of curve 32 expressions second electric mechanical switch.
(a) of Figure 11 shows the state of each moment first electric mechanical switch and second electric mechanical switch to the equivalent electric circuit in (d).
Under the on-state according to electric mechanical switch of the present invention, the two all is in first electric mechanical switch and second electric mechanical switch under the on-state, that is, movable electrode contacts with fixed electrode, thereby the positional value of movable electrode is 0.The two applies drive control voltage to first electric mechanical switch and second electric mechanical switch.
Be set at 0 o'clock in 0 drive control voltage that is applied to first electric mechanical switch 22 and second electric mechanical switch 24 constantly, as shown in figure 10, in the t1 moment (about 0.25 μ s), the position of second movable electrode of second electric mechanical switch is 0.2 μ m.Therefore, can guarantee to isolate by second electric mechanical switch 24 separately.And electric mechanical switch of the present invention enters off-state then with high speed operation.
At t2 constantly (about 2 μ s), the position of second movable electrode of second electric mechanical switch 24 is near original position, i.e. 1.5 μ m, and first movable electrode of first electric mechanical switch 22 then arrives at the position of 0.2 μ m.Therefore, only just can guarantee abundant isolation by first electric mechanical switch 22.
In the t3 moment (about 2.5 μ s), second movable electrode of second electric mechanical switch 24 is got back to latched position, that is, and and near the position corresponding to 0 displacement.
At this t3 constantly, first electric mechanical switch 22 has been guaranteed isolation separately.Therefore, even, also fully guaranteed the isolation of high-frequency signal according to whole electric mechanical switch of the present invention applying under the situation that drive control voltage locks second movable electrode thus to second electric mechanical switch 24 in this state.
Carrying out the required control voltage of this locking can be small voltage, because the slit between second movable electrode that returns and the fixed electrode is little.
Therefore, according to the present invention, can be by first electric mechanical switch be combined the electric mechanical switch that realization has the high-speed response characteristic with second electric mechanical switch.
According to first embodiment, shown in Figure 12 (a), fixed electrode 62 and movable electrode 64 are parallel-plate-type electrode 64.But shown in Figure 12 (b), fixed electrode 66 and movable electrode 68 can be comb flute profile electrodes 69.
Can described electric mechanical switch be configured to the capacitor type switch by forming dielectric material on one or two surface of facing mutually at movable electrode and fixed electrode.
And, although quoted the material of Al as movable electrode,, also can adopt other metal materials except Al, for example, Mo, Ti, Au and Cu.Perhaps, can adopt electric conducting material.
And, can adopt by deposit on the surface of tabular silicon materials to have girder construction that the metal part of nano-grade size constructs as movable electrode.And the bimorph cell that can utilize piezoelectric element, marmem, electromagnetism distortion element and utilize the bimorph effect is as movable electrode.
Although under the situation that adopts parallel-plate-type and comb flute profile electrode, movable electrode is drawn in towards the fixed electrode that is formed on the substrate,, movable electrode can be configured to respect to the substrate levels operation.
Next, will be described below the modification of the first embodiment of the present invention.Figure 13 is the schematic diagram of electric mechanical switch, in described electric mechanical switch, and the operation of movable electrode along continuous straight runs.
As shown in figure 13, electric mechanical switch 70 has first movable electrode 74 and second movable electrode 76, the two ends of each electrode are placed also and are fixed on first anchor 72 and second anchor 73 that is formed on the silicon substrate 2, and electric mechanical switch 70 also has and is formed between these movable electrodes and the fixed electrode 78 all thicker than each movable electrode.First movable electrode 74 and second movable electrode 76 are parallel to fixed electrode 78 and form, thereby provide predetermined slit between fixed electrode and each movable electrode.
Slit between first movable electrode 74 and the fixed electrode 78 has the width of the amplitude peak of first movable electrode 74 that equals to carry out intrinsic vibration.Slit between second movable electrode 76 and the fixed electrode 78 has the width of the amplitude peak of first movable electrode 76 that equals to carry out intrinsic vibration.These slits differ from one another.
By comprising first movable electrode 74 and fixed electrode 78 structures first electric mechanical switch.By comprising second movable electrode 76 and fixed electrode 78 structures second electric mechanical switch.
For example, to first movable electrode, 14 configurations (shape), make that thickness is 2.5 μ m, width is 0.4 μ m, and length is 500 μ m, and the slit between first movable electrode 14 and the fixed electrode is 0.2 μ m.To second movable electrode, 76 configurations (shape), make that thickness is 5 μ m, width is 0.4 μ m, and length is 500 μ m, and the slit between first movable electrode 14 and the fixed electrode is 1.5 μ m.Adopt this mode to the movable electrode configuration, make described modification have and the first embodiment confers similar advantages.
Incidentally, represent and the identical parts shown in Fig. 2 with identical Reference numeral.
In the electric mechanical switch 70 with this structure, first movable electrode 74 and second movable electrode 76 are with respect to the substrate levels operation.
Under the situation of movable electrode with respect to the substrate levels operation, can easily form slit between slit between first electric mechanical switch and the fixed electrode and second electric mechanical switch and the fixed electrode, make these slits differ from one another.All the other operations are similar with first embodiment.
Above-mentioned electric mechanical switch may not be driven by electrostatic force.For example, the heat and the piezoelectric element that can adopt electromagnetic force, utilize thermal source to obtain come the driving machine electric switch.
Can adopt above-mentioned electric mechanical switch as antenna diversity (antenna diversity) DPDT (dpdt double-pole double-throw (DPDT)) switch that requires to carry out the WLAN switched at a high speed etc.
Next, will be described below manufacture method according to the electric mechanical switch of first embodiment.
Figure 14 is the external view of silicon substrate, forms the unit elements of electric mechanical switch in described silicon substrate.
By on it, applying resist film, to having the substrate exposure of predetermined mask pattern, next develop again/etching afterwards, remove resist film thus and form silicon substrate shown in Figure 14 2 with reservation shape.
In silicon substrate 2, adopt a pair of first concave portions 82 to fix and place first movable electrode, adopt a pair of second concave portions 84 to fix and place second movable electrode 16, adopt a pair of the 3rd spill partly to take out fixed electrode in 86 from its, adopt a pair of the 4th spill partly 88 to form fixed electrodes 18.
Figure 15 is the external view of seal cover glass.
The similar flat board of the shape of seal cover glass 3, it has paired jut 92,94 and 96, and it corresponds respectively to first concave portions 82, second concave portions 84 and the 3rd concave portions 86 that is provided with on silicon substrate 2.
The Figure 16 that comprises diagram (a) to (e) is the schematic diagram of the manufacture process of this electric mechanical switch of explanation.Figure 16 (a) is the cross-sectional view that the B-B line along Figure 14 obtains.Remaining each diagram all is the cross-sectional view in the same cross section of this electric mechanical switch of explanation.
At first, by vacuum evaporation or sputter at deposit Al layer on the silicon substrate 2.Afterwards, on it, apply resist film with predetermined pattern.Next, adopt this resist film the Al layer to be carried out wet etching or dry etching as mask.Fixed electrode 18, third electrode terminal 6 and the 6th electrode terminal 9 (referring to Fig. 2 and Figure 16 (b)) have been formed thus.
Next, form sacrifice layer 102 (referring to Figure 16 (c)) by resist.Afterwards, by sputtering at deposit Al layer on this sacrifice layer.After this, adopt resist film 104, the Al layer is carried out dry etching by ecr plasma as mask with predetermined pattern.First movable electrode 14 and second movable electrode 16 (referring to Figure 16 (d)) have been formed thus.
Afterwards, remove resist film 104 and sacrifice layer 102 by plasma ashing.Formed each girder construction of first movable electrode 14 and second movable electrode 16 thus.In step-down equipment or helium pad device, adopt the jut realization silicon substrate 2 of seal cover glass 3 and aiming at of seal cover glass 3.Next, with seal cover glass 3 and silicon substrate 2 each other anode be connected (referring to Figure 16 (e)).
Can form film like girder construction thus such as first movable electrode 14 and second movable electrode 16.And, can produce so a kind of electric mechanical switch, wherein, handle or filled dried helium around having carried out pressure drop in each is suitable for carrying out the space of movable electrode of high speed operation.
Second embodiment
Next, will be described below second embodiment.
Figure 17 is the schematic diagram of structure of the example of explanation second embodiment.
There is not restriction in structure and material to electric mechanical switch.As long as shape by setting movable electrode and material obtain corresponding to the intrinsic vibration of movable electrode, smaller or equal to the response time of the electric mechanical switch of desired value, just can adopt the shape and the material that set.In a second embodiment, implement the relative variation of spring force.
As shown in figure 17, electric mechanical switch 200 according to second embodiment has first movable electrode 202, second movable electrode 204 and the 3rd movable electrode 206, and the two ends of each movable electrode are placed and are fixed on first anchor 201 and second anchor 203 that is formed on the silicon substrate 2.Formed movable electrode faces with each other, the extension that is parallel to each other, and have the predetermined slit that is arranged between the adjacent movable electrode.Movable electrode is configured at plate-girder, and described movable electrode has different spring forces respectively.Form second movable electrode 203, make the spring force of second movable electrode 203 be better than the spring force of first movable electrode 202 and the 3rd movable electrode 206.Construct first movable electrode 202 and the 3rd movable electrode 206, make the spring force of the movable electrode 202 of winning equal or different with the spring force of the 3rd movable electrode 206.
With regard to example shown in Figure 17, electric mechanical switch has second electrode terminal 212 that plays the signal input terminal effect, also has the 4th electrode terminal 214 and the 6th electrode terminal 216 that play the signal output terminal effect.Thus, this electric mechanical switch can be configured to SPDT (single-pole double throw) switch.
In addition, the end at first movable electrode 202 forms first electrode terminal 211 and the 6th electrode terminal 216.End at second movable electrode 204 forms second electrode terminal 212 and the 5th electrode terminal 215.End at the 3rd movable electrode 206 forms third electrode terminal 213 and the 4th electrode terminal 214.Each electrode terminal can be connected to the control voltage source that applies electrostatic force between the movable electrode that is suitable for facing towards each other.
In electric mechanical switch shown in Figure 17 200, by comprising first movable electrode 202 and second movable electrode, 204 structures, first electric mechanical switch.By comprising second movable electrode 204 and the 3rd movable electrode 206 structures second electric mechanical switch.
Incidentally, although not shown, electric mechanical switch 200 sealed cover glasses cover.By filling dried helium or being in the inside that the pressure of reduction gets off to safeguard electric mechanical switch 200.
And, make corresponding response time of natural frequency with second movable electrode 204 that can be electrically connected with first movable electrode 202 and the 3rd movable electrode 206 smaller or equal to Expected Time Of Response by the structure electric mechanical switch.Thereby, can movable electrode be subjected to displacement in predetermined response to.
For example, be under the situation of 0.2 μ s in the response time of expection, natural frequency should be smaller or equal to 5MHz.
More specifically, can adopt equation (1) and (2) natural frequency to be set to value, for example smaller or equal to 5MHz, (internal stress is 50MPa adopting aluminium, Young's modulus is 70GPa, and Poisson's ratio is 0.25, and density is 2.69kg/m3) as the material of movable electrode, and the data of representing its shape, that is, width w is 1 μ m, and thickness D is 10 μ m, length L is under the situation of 50 μ m, and natural frequency is 5MHz.In addition, the space between the movable electrode is set to 2.4 μ m.
Basically, second movable electrode 204 is remained under such state, that is, under initial condition second movable electrode 204 all the time with first movable electrode 202 and the 3rd movable electrode 206 in one be electrically connected.That is to say that in electric mechanical switch 200, one in first electric mechanical switch and second electric mechanical switch is in on-state, another electric mechanical switch just keeps off-state.
In example shown in Figure 17, apply drive control voltage to the 3rd movable electrode 206.By electrostatic force second movable electrode 204 and the 3rd movable electrode 206 are in contact with one another, or mutual capacitive coupling.At this moment, do not apply drive control voltage to second movable electrode 204 and first movable electrode 202.
Figure 18 is the curve chart of the displacement of explanation second movable electrode.
Under initial condition shown in Figure 17, the drive control voltage that is applied to the 3rd movable electrode 206 is set to 0, release electrostatic power thus, in this case, second movable electrode 204 vibrates with natural frequency by its restoring force between first movable electrode 202 and the 3rd movable electrode 206, as shown in figure 18.At this moment, reduce damping effect.Therefore, the value of the damping effect in the switch is (1/25) of the value of the damping effect in the atmospheric air.
Next, will be described below the handover operation of second embodiment.
At this moment, applying drive control voltage to the 3rd movable electrode 214, and second under the state that is in contact with one another of movable electrode 204 and the 3rd movable electrode 214, is set to 0 and 0 applying drive control voltage to first movable electrode 202 constantly by the drive control voltage that is applied to the 3rd movable electrode 214 simultaneously.
At this moment, second movable electrode 204 passes through strong spring power to first movable electrode, 202 high-speed mobile.In addition, first movable electrode 202 with weak relatively spring force produces response to this under the influence that acts on the electrostatic force between first movable electrode 202 and second movable electrode 204.Afterwards, first movable electrode 202 is more near second movable electrode 204 and be locked.At this moment, the drive control voltage of 3V is enough to allow first movable electrode 202 with 204 lockings of second movable electrode.
According to electric mechanical switch,, also can realize the high speed handover operation even under low driving voltage with this structure.
Simultaneously, when applying drive control voltage for some reason and not on it, second movable electrode 204 just can be by first movable electrode 202 or by 206 lockings of the 3rd movable electrode.Thus, can make second movable electrode 204 be in its displacement is 0 state.
Being in its displacement at second movable electrode is under 0 the state, needs sizable drive control voltage to come by apply electrostatic force on it second movable electrode 204 to be pulled to first movable electrode 202 or the 3rd movable electrode 206.With regard to above-mentioned movable electrode, must on it, apply 44V voltage.
Therefore, be in on-state in order to make one of first electric mechanical switch and second electric mechanical switch, second movable electrode is suitable for adopting another drive unit rather than draws in by the electrostatic force that is produced by the voltage that puts between the movable electrode.
For example, can adopt by on it, applying structural detail self that voltage produces deformation, for example piezoelectric element, marmem, bimorph cell and electromagnetism distortion element as drive unit.
For example, can provide to be suitable for second moving element of deformation by on it, applying initial voltage, rather than second movable electrode 204.When this second moving element during more near the 3rd movable electrode 206, can apply drive control voltage to the 3rd movable electrode 206, adopt electrostatic force to lock second moving element thus.After this, can cancel the voltage that applies to second moving element.
Perhaps, can utilize mechanical probe (mechanical probe) that second movable electrode 204 is drawn in towards first movable electrode 202 or the 3rd movable electrode 206.When drawing in this second movable electrode 204, apply drive control voltage to first movable electrode 202 or the 3rd movable electrode 206.
Rely on this structure, the driving voltage that is applied to first movable electrode 202 and the 3rd movable electrode 206 can be reduced to low-voltage.Electric mechanical switch with speed-sensitive switch characteristic can be provided.
The 3rd embodiment
Next, will be described below the third embodiment of the present invention.Figure 19 is the top view of the electric mechanical switch of explanation a third embodiment in accordance with the invention.Similar with first embodiment, comprise a plurality of switches according to the electric mechanical switch of the 3rd embodiment with different spring forces.The 3rd embodiment prevents to produce such defective: even first movable electrode is fixed the situation of electrode locking for some fault under, also can't draw in second movable electrode with strong spring power that is in off-state; And second movable electrode finally mediate, thereby make first movable electrode and second movable electrode all be in off-state, this and first embodiment are similar.
That is to say, even under the effect of some fault, do not apply when first movable electrode is locked to the required voltage of fixed electrode from the outside to it, each of first movable electrode and second movable electrode also can arrive the centre position by free vibration, thereby makes first movable electrode and second movable electrode all be in off-state.
At this moment, because second movable electrode has strong spring power, therefore, need high pull-in voltage to draw in the electrode that is in off-state, and lock described electrode.
The 3rd embodiment provides the following structure that prevents to produce the problems referred to above.
This switch comprises input terminal 303 and two lead-out terminals 301 and 302, as shows signal structure shown in Figure 19 of this switch.
Input terminal 303 is connected to taller springs movable electrode 306.Lead- out terminal 301 and 302 is connected to the first low spring movable electrode 304 and the second low spring movable electrode 305 respectively.The taller springs movable electrode differs from one another with the relative value of the spring force of the first and second low spring movable electrodes.Similar with first embodiment, can be according to shape, material behavior and the slit control spring constant of spring.By leg portion 310 movable electrode 304 is fixed to substrate to 306.And, hang down spring movable electrode 304 and taller springs movable electrode 306 mutual mechanical connections by coupling part 307 with first.Similarly, by coupling part 307 taller springs movable electrode 306 and second is hanged down the mutual mechanical connection of spring movable electrode.In addition, in the zone that the first low spring movable electrode is contacted when the substrate direction is subjected to displacement and taller springs movable electrode 306 another of the local contact of institute when the substrate direction is subjected to displacement regional in formation first fixed electrode 308.
The spring force of coupling part 307 is less than the spring forces of the first and second low spring movable electrodes, and coupling part 307 is made of insulating element.First fixed electrode 308 and second fixed electrode 309 spatially are separated from each other.First fixed electrode 308 and 309 the two the fully electricity isolation each other of second fixed electrode.Unless taller springs movable electrode 306 contacts with first or second electrode 308 or 309, otherwise will between first fixed electrode 308 and second fixed electrode 309, fully set up isolation.
Next, will be described below the basic operation of switch.Present embodiment is used as the SPDT switch.But, also can be with present embodiment as spst switch.Will be described below a kind of handle outputs to lead-out terminal 301 from the signal of input terminal 303 inputs method.Externally between the taller springs movable electrode 306 and the first low spring movable electrode 304, apply control signal.Between movable electrode and fixed electrode, provide potential difference, produce electrostatic force thus.Afterwards, draw in first low spring movable electrode 304 and the taller springs movable electrode 306 towards fixed electrode.Afterwards, taller springs movable electrode 306 contacts and is electrically connected with first fixed electrode 308 with the first low spring movable electrode 304.By taller springs movable electrode 306, first fixed electrode 308 and the signal of the first low spring movable electrode 305 from lead-out terminal 301 outputs from input terminal 303 inputs.Similarly, signal is being exported under the situation of lead-out terminal 302, suggestion is drawn in second low spring movable electrode 305 and the taller springs movable electrode 306 towards substrate, and the second low spring movable electrode 305 and taller springs movable electrode 306 are electrically connected with second fixed electrode 309.
Next, the transient operation of described switch is described with reference to Figure 20.Diagram shown in Figure 20 is the cross-sectional view that obtains along A-A ' line shown in Figure 19.In the moment (a), low spring movable electrode 304 and 305 is in off-state.Taller springs movable electrode 306 is locked and contact with second fixed electrode 309 with first fixed electrode 308.In this state, the first low spring movable electrode and the second low spring movable electrode are in off-state.Shielded signal thus.
At this moment, apply control signal to the first and second low movable electrodes.Thereby potential difference is provided betwixt, produces electrostatic force thus.Draw in the first low spring movable electrode 304 and the second low spring movable electrode 305 towards substrate.The first low spring movable electrode 304 contacts and is electrically connected with first fixed electrode 308.The second low spring movable electrode 305 contacts and is electrically connected with second fixed electrode 309.On at least one contact-making surface between the electrode respect to one another, form dielectric film, prevent that thus the DC electric current from flowing, described contact-making surface is selected from one group first low spring movable electrode 304 and the second low spring movable electrode 305 and one group of first fixed electrode 308 and second fixed electrode 309 respectively.
The first and second low spring movable electrodes 304 and 305 have little spring power.Thus, draw in the first and second low spring movable electrodes 304 and 305 at a high speed with the small electric potential difference.Thereby make switch enter on-state in the moment (b).
Next, will be described below the operation that disconnection is in the switch under this on-state.Be in moment (b) of on-state at switch, cancellation is according to its locking first and second low spring movable electrodes 304 and 305 and the potential difference of taller springs movable electrode 306.So, discharge the first and second low spring movable electrodes 304 and 305 and taller springs movable electrode 306, and begin to carry out free oscillation.
At this moment, to discharge taller springs movable electrode 306 at a high speed with strong spring power.But taller springs movable electrode 306 is connected to the first and second low spring movable electrodes 304 and 305.Therefore,, discharge the first and second low spring movable electrodes 304 and 305 power that upwards promote in (c) generation constantly to promote first and second the high speeds than low spring movable electrodes 304 and 305.
In the moment (d), significantly overshoot of taller springs movable electrode 306 (overshoot).But at this moment, this has prevented by first and second low movable one poles 304 of spring of coupling part 307 connections and 305 significantly overshoots.
In addition, suggestion turns back to the taller springs movable electrode 306 of fixed electrode (i.e. first and second fixed electrodes 308 and 309) side in (f) locking constantly.
Thereby, taller springs movable electrode 306 is connected to the first and second low spring movable electrodes 304 and 305 by coupling part 307.Therefore, can relax overshoot.And, can promote the high speed of the first and second low spring movable electrodes 304 and 305 to discharge.
Suppose that switch will enter the state shown in Figure 21 (a) by free oscillation so owing to some fault does not have to have discharged taller springs movable electrode 306 thus to the electrode application voltage that is suitable for locking taller springs movable electrode 306.Need high pressure to go into taller springs movable electrode 306, thereby locking is in the taller springs movable electrode 306 of this state to fixed electrode (first and second fixed electrodes 308 and 309) layback.
Thereby, at first, shown in Figure 21 (b), draw in the first and second low spring movable electrodes 304 and 305 towards fixed electrode (first and second fixed electrodes 308 and 309).At this moment, taller springs movable electrode 306 is connected to the first and second low spring movable electrodes 304 and 305.Therefore, taller springs movable electrode 306 is subjected to displacement along the substrate direction.Electrostatic force is directly proportional with the inverse square of distance, thereby can reduce and draw in the required voltage of taller springs movable electrode 306.
And, when under the situation of the pull-in voltage that obtains expection under this operation, in carrying out the overshoot of intrinsic vibration, repeats the taller springs movable electrode drawing in and discharging of the first and second low spring movable electrodes.Then, the excitation first and second low spring movable electrodes.Increased Oscillation Amplitude.Under the pull-in voltage of expection, can lock movable electrode.
The connection status that the taller springs movable electrode and first and second that can connect by coupling part 307 according to the installation site control of coupling part 307 hangs down the spring movable electrodes.
The fixing movable electrode in two ends is not all to vibrate with uniform amplitude in all zones.Movable electrode vibrates with amplitude peak near the center of the beam that plays the movable electrode effect.On the contrary, movable electrode vibrates hardly near leg portion 310.Therefore, the connection status of movable electrode changes according to the position that movable electrode interconnects in the residing beam.Near amplitude has peaked position under the interconnective situation, the influence of electrode is maximized at movable electrode, and therefore connection therebetween is very strong.That is to say,, when the moment (c) discharges taller springs movable electrode 306, support that discharging first and second with powerful power hangs down spring movable electrodes 304 and 305 when as shown in figure 20.On the contrary, then restricted the vibration of movable electrode.Lost the vibrational energy of taller springs movable electrode 306.Reduce free-running amplitude, thereby increased latch voltage.
Otherwise under near the interconnective situation leg portion 310, the state of movable electrode becomes near the state that coupling part 307 is not provided at movable electrode.Thereby, do not promote the release of the first and second low spring movable electrodes.Therefore, the position of essential control connection part 307 is to satisfy desired technical specification.
Incidentally, in explanation of the present invention, the example that adopts two low spring movable electrodes has been described.But, only adopt low spring movable electrode to constitute switch and also can obtain confers similar advantages.
Industrial applicibility
Electric mechanical switch according to the present invention has been realized carrying out high speed and has been connected, disconnected behaviour under low driving voltage Do. Can advantageously electric mechanical switch according to the present invention be used as RFMEMS switch, especially requirement Carry out at a high speed required antenna diversity DPDT (DPDT) switch of wireless LAN of switching.

Claims (22)

1. electric mechanical switch comprises:
First electric mechanical switch, it is suitable for switching on and off based on the displacement of first beam, and described first beam can be replied by weak relatively spring force; And
Second electric mechanical switch, it is suitable for switching on and off based on the displacement of second beam, and described second beam can be replied by strong relatively spring force,
Wherein, under initial condition, described electric mechanical switch is under the off-state that described first electric mechanical switch disconnects and described second electric mechanical switch is connected.
2. electric mechanical switch according to claim 1, wherein, by the applying and cancel one of operation of actuating force, described first beam is subjected to displacement by described initial condition, makes described first electric mechanical switch connect, and makes described electric mechanical switch enter on-state thus.
3. electric mechanical switch according to claim 1, wherein, under described first electric mechanical switch and the two situation about all connecting of described second electric mechanical switch, cancel the displacement of described first beam and the displacement of described second beam simultaneously, reply operation to carry out, thereby disconnect second electric mechanical switch, make described electric mechanical switch enter off-state thus.
4. electric mechanical switch according to claim 1, wherein, by disconnecting described second electric mechanical switch, described second beam begins to carry out intrinsic vibration; And
Wherein, when described second beam turns back to described second electric mechanical switch and disconnects its residing displaced position near situation under, applying and cancel described second beam of one of operation locking by actuating force.
5. electric mechanical switch according to claim 1, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on electrostatic force.
6. electric mechanical switch according to claim 1, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on electromagnetic force.
7. electric mechanical switch according to claim 1, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on piezoelectric effect.
8. electric mechanical switch according to claim 1, wherein, one of displacement of the displacement of described at least first beam and described second beam is based on thermal expansion.
9. electric mechanical switch according to claim 1 also comprises public fixed electrode, and parallel surface is right with it by the space for described first beam and described second beam,
Wherein, by described fixed electrode and described first electric mechanical switch of described first beam construction; And
Wherein, by described fixed electrode and described second electric mechanical switch of described second beam construction.
10. electric mechanical switch according to claim 9 wherein, is made as amplitude peak less than described first beam and the every person's of described second beam intrinsic vibration with described space to fixed electrode.
11. electric mechanical switch according to claim 9 wherein, has only when first electric mechanical switch and connects and second electric mechanical switch when also connecting, described electric mechanical switch just is in on-state.
12. electric mechanical switch according to claim 1, wherein, described first beam and described second beam layout that is parallel to each other;
Wherein, being arranged in parallel with it can be by the 3rd beam of spring force answer, and described spring force is weaker than the spring force of described second beam relatively;
Wherein, by described first beam and described first electric mechanical switch of described second beam construction; And
Wherein, by described second beam and described second electric mechanical switch of described the 3rd beam construction.
13. electric mechanical switch according to claim 12 wherein, forms space between described second beam and described first beam and the every person of described the 3rd beam according to the amplitude peak of the intrinsic vibration of described second beam.
14. electric mechanical switch according to claim 12, wherein, under the situation that the displacement of described first beam, described second beam and described the 3rd beam all is cancelled, make described second beam more near in described the 3rd beam by mechanical probe, by the applying and cancel one of operation described the 3rd beam is subjected to displacement of actuating force, lock described second beam thus.
15., wherein, place air pressure to be different from the environment of atmospheric pressure described first electric mechanical switch and described second electric mechanical switch according to a described electric mechanical switch in the claim 1 to 14.
16. according to a described electric mechanical switch in the claim 1 to 14, wherein, described second electric mechanical switch only disconnects described first electric mechanical switch and obtains the required time of predetermined isolated.
17. according to a described electric mechanical switch in the claim 1 to 14, wherein, the cycle of the intrinsic vibration of described second beam equals described first beam and reaches described first beam and obtain the enough isolation required time of residing position.
18. according to a described electric mechanical switch in the claim 1 to 14, wherein, the cycle of the intrinsic vibration of described second beam reaches described first beam greater than described first beam and obtains enough to isolate the required time of residing position.
19. according to a described electric mechanical switch in the claim 1 to 14, wherein, the cycle of the intrinsic vibration of described second beam reaches described first beam less than described first beam and obtains enough to isolate the required time of residing position.
20. electric mechanical switch according to claim 1, wherein, when described first electric mechanical switch is connected with signal condition by switching to by state under the situation of masked state, described second beam reaches described second beam and obtains the necessary residing position that isolates, arrive described first beam up to described first beam and obtain the predetermined isolated desired position, described second beam is then got back to initial lock-out state once more.
21. electric mechanical switch according to claim 1 also comprises:
Low spring movable electrode by described first beam construction;
By the taller springs movable electrode of described second beam construction, it is parallel to described low spring movable electrode and arranges; And
In the face of the fixed electrode of described first beam and the setting of described second beam,
Wherein, described first electric mechanical switch comprises the low spring movable electrode and described first fixed electrode of described first beam;
Wherein, described second electric mechanical switch comprises the taller springs movable electrode and described first fixed electrode of described second beam;
Wherein, described first beam and described second beam are by the mutual mechanical connection in coupling part; And
Wherein, described second beam responds the displacement of described first beam and is subjected to displacement.
22. electric mechanical switch according to claim 21, wherein, described second beam is connected to input terminal; And
Wherein said first beam and described second beam are connected to first lead-out terminal and second lead-out terminal respectively.
CN 200680000113 2005-01-21 2006-01-20 Electromechanical switch Pending CN1942986A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2005014019 2005-01-21
JP014019/2005 2005-01-21
JP012529/2006 2006-01-20

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103552979A (en) * 2013-11-14 2014-02-05 东南大学 Heat-static strong recovering type MEMS four-point support hanging beam structure
CN103552973A (en) * 2013-11-14 2014-02-05 东南大学 Micro cantilever beam structure with thermal-driving adhesion elimination mechanism in micro electro mechanical system
CN103964364A (en) * 2013-01-29 2014-08-06 中国科学院微电子研究所 Micro-nano electrostatic force switch and manufacturing method thereof

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103964364A (en) * 2013-01-29 2014-08-06 中国科学院微电子研究所 Micro-nano electrostatic force switch and manufacturing method thereof
CN103964364B (en) * 2013-01-29 2016-12-28 中国科学院微电子研究所 Micro-nano electrostatic force switch and manufacturing method thereof
CN103552979A (en) * 2013-11-14 2014-02-05 东南大学 Heat-static strong recovering type MEMS four-point support hanging beam structure
CN103552973A (en) * 2013-11-14 2014-02-05 东南大学 Micro cantilever beam structure with thermal-driving adhesion elimination mechanism in micro electro mechanical system
CN103552979B (en) * 2013-11-14 2015-10-28 东南大学 A kind of heat-electrostatic reply type by force MEMS four-point supporting hanging beam structure
CN103552973B (en) * 2013-11-14 2015-12-30 东南大学 Adhere to the micro cantilever structure of eliminating machine with thermal drivers in micro mechanical system

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