CN1723619A - Mechanical resonator - Google Patents

Abstract

A mechanical resonator is constructed such that it has a vibration body (1) that performs a mechanical resonant vibration and also has an electrode (2) located in the vicinity of the vibration body (1) and such that it is shaped into the surface shape of the electrode (2) when deformed during a resonance mode of the vibration body (1), whereby the electrostatic capacitance change per unit vibration displacement amount can be enlarged. In this way, a mechanical resonator can be realized which performs an effective electricity-to-machine or machine-to-electricity conversion. Moreover, this mechanical resonator can be used to realize a small-sized, high-performance filter circuit or switch circuit in a high-density integrated electrical circuit.

Description

Mechanical resonator

Technical field

The present invention relates to mechanical resonator, particularly in the integrated circuit of high density, realize the resonator of small-sized, high performance filter circuit or switching circuit.

Background technology

With reference to Figure 22 the existing mechanical resonator is described.Figure 22 simply is illustrated in document FrankD.Bannon III John R.Clark, and Clark T.-C.Nguyenc work " High-Q HFMicroelectromechanical Filters " (IEEE Journal of Solid-State Circuits, Vol.35, No.4, pp512-526, April 2000) in the figure of the mechanical oscillation Filter Structures introduced.

This filter forms by carry out film on silicon substrate.By incoming line 104, outlet line 105, relative with each circuit and have 1 micron or following space and the double bracing beam 101,102 that disposes and the bondbeam 103 of these two beam combinations is constituted.Electrostatic force takes place in signal and beam 101 capacitive coupling from incoming line 104 inputs on beam 101.Owing to only near the resonance frequency of the frequency of signal and the elastic construction body of forming by beam 101,102 and bondbeam 103, just evoke mechanical oscillation when consistent, by further the variation of these mechanical oscillation as the electrostatic capacitance of 102 on outlet line 105 and beam being detected, can take out the filtering output of input signal.

In the occasion of the double bracing beam of square-section, suppose that modulus of elasticity is that E, density are that ρ, thickness are that h, length are L, resonance frequency f becomes following formula.

$f=1.03\frac{h}{L^2}\sqrt{\frac{E}{\mathrm{\ρ}}}---\left(1\right)$

If make material, suppose E=160GPa, ρ=2.2 * 10 with polysilicon ³Kg/m ³, suppose size L=40 μ m, h=1.5 μ m again, f=8.2MHz then can constitute the filter of about 8MHz frequency band.Compare with the filter that constitutes by passive circuits such as capacitor and coils, can obtain the high rapid frequency selective characteristic of Q value by using mechanical resonance.

But above-mentioned existing structure has following restriction for the filter of the high wavestrip of further formation.Promptly by (formula 1) as can be known, the first change material makes E/ ρ become big.But big if E becomes, even make the power of beam deflection identical, the displacement of beam also can diminish, and the displacement that detects beam becomes difficult.In addition, if the ratio d/L of the length L of the amount of bow d at the beam center of the index of hypothesis expression beam deflection easness when adding dead load on the surface of double bracing beam and beam, then d/L is represented by the proportionate relationship of following formula.

$\frac{d}{L}\&Proportional;\frac{L^3}{{\mathrm{<figure-callout\; id="3"\; label="h"\; filenames="A200480001767.000271.png,A200480001767.000281.png"\; state="\{\{state\}\}">h</figure-callout>}}^3}\&CenterDot;\frac{1}{E}---\left(2\right)$

Therefore, in order in the value that keeps d/L, to improve resonance frequency, at least need to change E, and want the low material of density p, and as equate with the Young's modulus of polysilicon, low density material must use CFRP composite materials such as (Carbon Fiber Reinforced Plastics).It is very difficult that this situation constitutes the milli machine vibration filter with semiconductor machining.

The second method of not using this composite material is the size that changes (formula 1) central sill, strengthens hL ^-2Method.But h strengthens and L diminishes with the d/L as (formula 2) of crooked easness index is diminished, and detects deflection of beam and becomes difficult.

As if the relation of representing log (L) and log (h) about (formula 1) and (formula 2) in Figure 23, straight line 191 is relations of being obtained by (formula 1), and straight line 192 is relations of being obtained by (formula 2).In this Figure 23, if select than being that starting point tilts the straight line of " 2 " by the L and the h of last scope (regional A) with existing size A point, it is big that f just becomes, if select than the straight line of tilt " 1 " L and the h by scope (area B) down, d/L with regard to change greatly.Thereby hachure part (zone C) is can guarantee the deflection of beam amount and improve the L of resonance frequency and the scope of h among the figure.

As shown in Figure 23, for the high frequencyization of mechanical oscillation filter, L and h both sides' size microminiaturization is a necessary condition, makes L and h miniaturization with identical ratio, promptly on 1 the straight line of tilting and L and h are diminished is the adequate condition of the hachure part of Figure 23.

Like this, the existing mechanical resonator is by making the compact in size of mechanical oscillation body, and resonance frequency is by high frequencyization, but even so, because vibration of beam diminishes, detects the signal weaker of vibration inevitably, thereby have the problem that disturbed by external force.

Summary of the invention

The object of the present invention is to provide a kind of small mechanical resonator of high performance of the circuit block of realizing filter etc.

In order to solve this technical problem, shape when the present invention is out of shape with resonance mode by the electrode surface shape being made vibrating body, realization strengthens the capacitance variations of the per unit displacement of the vibrating body that carries out synchronous vibration, the signal of telecommunication is converted to the structure of mechanical oscillation efficiently or mechanical oscillation are converted efficiently to the structure of the signal of telecommunication.

The mechanical resonator of the present invention's first mode have the vibrating body that carries out mechanical resonance vibration and this vibrating body when synchronous vibration near and to the electrode of the amplitude direction curved configuration of synchronous vibration.Thus, the capacitance variations of per unit displacement of carrying out the vibrating body of synchronous vibration strengthens, and can convert the signal of telecommunication efficiently to mechanical oscillation or mechanical oscillation are converted to the signal of telecommunication efficiently.

The mechanical resonator of the present invention's second mode is that the surface configuration of electrode of the bending of first mode shape when deforming with resonance mode with vibrating body is identical in addition.Thus, because the electrostatic capacitance of this vibrating body can be increased to maximum limit relatively, so can strengthen the capacitance variations of the per unit displacement of the vibrating body that carries out synchronous vibration, the signal of telecommunication is converted to mechanical oscillation efficiently or mechanical oscillation are converted to the signal of telecommunication efficiently.

In addition, the mechanical resonator of Third Way of the present invention is that the surface area of surface area ratio vibrating body of vibrating body electrode of opposite of first mode of the present invention or second mode is little.Thus, owing to the excess charges in the capacitive coupling that can be suppressed at vibrating body and electrode takes place, can cut down unwanted alternating current of sewing.Especially by make part that with resonance time amplitude becomes maximum vibrating body with and near configured electrodes not on the relative position, the relation between voltage and power, displacement and electric current is more approaching linear, can control at an easy rate.Or by making in the position relative with the end of vibrating body not configured electrodes, can be with the generation of simple STRUCTURE DEPRESSION excess charges.

In addition, the mechanical resonator of the cubic formula of the present invention has the vibrating body that carries out mechanical resonance vibration and electrode approaching with the resonance body, that vibrate with the resonance mode of identical resonance frequency.Thus, when not vibrating, electrostatic capacitance is all the same with parallel plate structure little, with resonant frequency vibration the time, because this ticker electrostatic capacitance becomes maximum relatively, can strengthen | the value of Δ C/ Δ y|.The result can reduce unwanted alternating current, and can become mechanical oscillation to electrical signal conversion efficiently, or efficiently mechanical oscillation is converted to the signal of telecommunication.

In addition, the mechanical resonator of the present invention's the 5th mode is also to have the grid bias power supply that is connected and produces electrostatic field with the vibrating body of the present invention's first to fourth mode with electrode between them, when receiving the change in voltage of resonance frequency between vibrating body and electrode, vibrating body carries out synchronous vibration.Thus, can become mechanical oscillation to electrical signal conversion efficiently.

In addition, the mechanical resonator of the present invention's the 6th mode further has the test section of the electrode of first to fourth mode according to the present invention and the change in voltage detection signal between the vibrating body, the vibrating body when vibrating by vibrating body and the variation of the electrostatic capacitance between the electrode, test section detects the signal that converts the signal of telecommunication from vibration to.Thus, can convert mechanical oscillation to the signal of telecommunication efficiently.

The mechanical resonator of the present invention's the 7th mode is in the present invention's first to fourth mode, at least one side of electrode and the vibrating body opposite face relative with electrode insulating barrier is set.Thus, can avoid the electrical short of vibrating body and electrode.Insulating barrier is the macromolecule particle with insulating properties and lubrification especially.Thus, because the thickness of insulating barrier is certain and polyfurolresin has lubrification,, the out of contior absorption affinity that is called as stiction is reduced even vibrating body contacts with polyfurolresin particle 5.

The present invention the mechanical resonator of formula from all directions is in the present invention's first to fourth mode, further be included on the surface of the vibrating body relative with electrode with the 1st contact electrode of vibrating body insulation configuration and with the chimeric ground of the 1st contact electrode and with the 2nd electrode of electrode insulation configuration.Thus, become Q value doubly, can the contact electrode be contacted with small voltage because the moving displacement of the vibrating body that is produced by electrostatic force is compared with quiet displacement.

Further has the grid bias power supply that is connected and between them, produces electrostatic field with described vibrating body with described electrode especially, when between vibrating body and electrode, receiving change in voltage, the vibrating body synchronous vibration, at the 1st contact electrode during, carry out Electrostatic Absorption with the voltage of grid bias power supply near the 2nd contact electrode.Thus, the displacement of the synchronous vibration of vibrating body can be controlled at the degree that clashes with electrode, because the moment of reacceesing, by introducing at described vibrating body and described interelectrode electrostatic force, described vibrating body is adsorbed on the described electrode, fix the 1st contact electrode and the 2nd contact electrode thereby can contact, so can realize utilizing this switching function.

In addition, the mechanical resonator of the present invention's the 9th mode is electricity parallel connection or the mechanical resonator that in series disposes a plurality of the present invention's first to fourth modes, and electrode also can be with the resonance mode vibration of the resonance frequency identical with vibrating body.

Like this by adjusting the number of suitable filter, particularly can make owing in high-frequency circuit, become the reflected signal minimizing that the impedance of problem does not match and produces, thereby can become mechanical oscillation to electrical signal conversion efficiently, and mechanical oscillation are re-used as signal of telecommunication taking-up.

In addition, the mechanical resonator of the present invention's the tenth mode is that the mechanical resonator of the present invention's first to the 9th mode is placed in the vacuum-packed shell of environment.Thus, because viscosity that can deaeration, can make the raising of Q value to the attenuating that vibrating body produces.

In addition, the filter of the present invention's the 11 mode is to use the filter of the mechanical resonator of the present invention's first to the 7th mode.

In addition, the switch of the present invention's the 12 mode is to use the switch of the mechanical resonator of the present invention all directions formula.

In addition, the circuit of the present invention's the 13 mode is to use the circuit of the mechanical resonator of the present invention's the first to the 12 mode.

According to above-mentioned the present invention, can realize the structure that efficiently electrical signal conversion is become the structure of mechanical oscillation and efficiently mechanical oscillation are converted to the signal of telecommunication.In addition, use mechanical resonator of the present invention also can in the integrated circuit of high density, realize small-sized and high performance filter circuit or switching circuit.

Description of drawings

Fig. 1 is the schematic diagram of structure of representing the mechanical resonator of transverse vibration first resonance mode waveform according to an embodiment of the present invention, that the electrode surface shape made the double bracing beam;

Fig. 2 is a schematic diagram of representing structure according to an embodiment of the present invention, electricity → mechanical transducer;

Fig. 3 is that expression is existing, the schematic diagram of the structure of the mechanical resonator of electrode being made the parallel flat shape;

Fig. 4 is a performance plot of representing the relation (δ max=1 μ m) of vibration displacement y of vibrating body according to an embodiment of the present invention, resonance and electrostatic capacitance C;

Fig. 5 is a performance plot of representing the relation (δ max=0.3 μ m) of vibration displacement y of vibrating body according to an embodiment of the present invention, resonance and electrostatic capacitance C;

Fig. 6 is a schematic diagram of representing structure according to an embodiment of the present invention, machinery → electric transducer;

Fig. 7 is a schematic diagram of representing mechanical resonance Filter Structures according to an embodiment of the present invention, that dispose side by side;

Fig. 8 is a vertical view of representing girder constructions according to an embodiment of the present invention, 6 fixeds;

Fig. 9 is a schematic diagram of representing the mechanical resonance Filter Structures of girder construction according to an embodiment of the present invention, that use Fig. 8, configured in series;

Figure 10 represents schematic diagram according to an embodiment of the present invention, that have the mechanical resonance Filter Structures of simple electricity → machinery → electric translation function;

Figure 11 A, Figure 11 B be represent according to an embodiment of the present invention, electrode also has the schematic diagram of structure of the mechanical resonator of resonant structure;

Figure 12 is a schematic diagram of representing the structure of mechanical resonator according to an embodiment of the present invention, that the electrode two ends are made insulating properties;

Figure 13 is a performance plot of representing the relation of vibration displacement y according to an embodiment of the present invention, in the structure of Figure 12 and electrostatic capacitance C;

Figure 14 is a schematic diagram of representing the structure of mechanical resonator according to an embodiment of the present invention, that the electrode central portion made insulating properties;

Figure 15 is a performance plot of representing the relation of vibration displacement y according to an embodiment of the present invention, in the structure of Figure 14 and electrostatic capacitance C;

Figure 16 is a schematic diagram of representing the structure of mechanical resonator according to an embodiment of the present invention, that have construction of switch;

Figure 17 represents schematic diagram according to an embodiment of the present invention, that used the insulating barrier of tetrafluoroethylene resin particle;

Figure 18 A to Figure 18 D is the schematic diagram of manufacturing process of the mechanical resonator of expression one embodiment of the present invention;

Figure 19 is the schematic diagram of structure of representing the mechanical resonator of transverse vibration first resonance mode waveform according to an embodiment of the present invention, that the electrode surface shape made cantilever beam;

Figure 20 A is the figure of the transverse vibration subresonance mode waveform of expression cantilever beam;

Figure 20 B is the schematic diagram of structure of representing the mechanical resonator of transverse vibration subresonance mode waveform according to an embodiment of the present invention, that the electrode surface shape made cantilever beam;

Figure 20 C is the schematic diagram of another structure of representing the mechanical resonator of transverse vibration subresonance mode waveform according to an embodiment of the present invention, that the electrode surface shape made cantilever beam;

Figure 20 D is a schematic diagram of representing the structure of mechanical resonator according to an embodiment of the present invention, that make Figure 20 B, Figure 20 C combination;

Figure 21 A to Figure 21 D is the schematic diagram of manufacturing process that the electrode of expression one embodiment of the present invention also has the mechanical resonator of resonant structure;

Figure 22 is the schematic diagram that the filter of existing mechanical resonator is used in expression;

Figure 23 is the performance plot of the relation of the size of conventional example, mechanical resonator and high frequencyization.

Embodiment

Below, with Fig. 1 to Figure 21 embodiments of the present invention are described.

(execution mode 1)

Fig. 1 is the schematic diagram of the mechanical resonator of embodiment of the present invention 1.

In Fig. 1, vibrating body 1 is 7 the double bracing beam of its two ends as fixing stiff end, thickness be h, wide for W, length be L.Electrode 2 is provided with near vibrating body 1.For fear of the electrical short that produces owing to both contacts, being provided with thickness on the surface of electrode 2 is that d, dielectric constant are the insulating barrier 3 of ε r.This moment, then the shape of vibrating body 1 under resonance mode was expressed from the next with the xy coordinate among the figure if hypothesis is utilized as the transverse vibration first resonance pattern of double bracing vibration of beam body 1.

$y\left(x\right)=y_{\max }\left[\frac{1}{1.6164}\right\{\mathrm{\&zeta;}(\cos \mathrm{kx}-\cosh \mathrm{kx})+\sin \mathrm{kx}-\sinh \mathrm{kx}\left\}\right]$

ζ＝-1.01781 k＝4.730/L (3)

Its maximum ymax (during x=2/L) is by the size of vibrating body exciting force, the thermal loss of vibrating body inside and the decisions such as viscosity of ambient air.

In addition, the concavity of the smoothness of the shape with (formula 3) is also made on the surface of electrode 2 and insulating barrier 3, and its degree of depth δ max gets bigger than the Oscillation Amplitude ymax of vibrating body 1.Particularly, the surface configuration of electrode 2 is as shown in the formula setting.

$y\left(x\right)=-{\mathrm{\&delta;}}_{\max }\left[\frac{1}{1.64164}\right\{\mathrm{\&zeta;}(\cos \mathrm{kx}-\cosh \mathrm{kx})+\sin \mathrm{kx}-\sinh \mathrm{kx}\left\}\right]-d---\left(4\right)$

In addition, if do not suppose because contacting of vibrating body that excessive exciting force etc. produce and electrode just need not be provided with insulating barrier 3.

Fig. 2 is the occasion that mechanical resonator is used for the conversion of electricity → machine, between vibrating body 1 and electrode 2, apply bias voltage Vb and AC signal Vi (Vi＜＜Vb).If consider the mass spring that the elastic vibration of this vibrating body 1 changes into to equivalent mass m is to apply the electrostatic force that is expressed from the next on this particle.

$F=-\frac{1}{2}\frac{\&PartialD;C}{\&PartialD;y}{(V_b+v_i)}^2\&cong;-\frac{1}{2}\frac{\&PartialD;C}{\&PartialD;y}({\mathrm{<figure-callout\; id="2"\; label="V\; b"\; filenames="A200480001767.000271.png,A200480001767.000281.png"\; state="\{\{state\}\}">V</figure-callout>}}_b^{}+2V_{\mathrm{bvi}})---\left(5\right)$

Wherein, F is an electrostatic force, and C is vibrating body and interelectrode electrostatic capacitance.In addition, first expression in the right is by the biasing force of bias voltage Vb generation.

According to (formula 5), the capacitance variations of vibrating body per unit displacement | y| is big more for Δ C/ Δ, and AC signal voltage is high more to the conversion efficiency of exciting force.Therefore, below expression use by the such existing parallel plate-type electrode structure of the structure of Fig. 2 of the electrode shape of (formula 4) expression and Fig. 3 compare can obtain bigger | Δ C/ Δ y|.

Fig. 4 is illustrated in when supposing d=0.1 μ m, ε r=1, δ max=1 μ m, L=40 μ m, W=20 μ m among Fig. 2, the displacement y of vibrating body central portion and the relation of electrostatic capacitance C.In Fig. 4 also together expression with the y of the structure of Fig. 3 of the value of identical d, ε r, δ max, L, W and the relation of C.The variation of mechanical resonator of the structure of Fig. 3 is made in the i.e. variation of mechanical resonator that the structure of Fig. 2 is made in characteristic curve 401 expression in Fig. 4, characteristic curve 402 expressions.

Near y=0, the structure of Fig. 3 is | Δ C/ Δ y|=3.1 * 10 ^-9[F/m], and the structure of Fig. 2 is improved to | Δ C/ Δ y|=9.8 * 10 ^-9[F/m].That is, promptly use identical AC signal Vi, also can obtain bigger synchronous vibration by the structure that adopts Fig. 2.In addition, for example the resonance amplitude at vibrating body is the scope internal vibration of ± 0.1 μ m, as long as can guarantee from circuit or mechanically suppress this amplitude or this amplitude more than amplitude, the value of δ max just can be set forr a short time.For example if hypothesis δ max=0.3 μ is m, the characteristic of y and C just becomes characteristic curve shown in Figure 5 501 and characteristic curve 502 is such, can further be improved in the structure of Fig. 2 | Δ C/ Δ y|=4.7 * 10 ^-8[F/m].

In addition, in Fig. 4, be counted as in the linear zone in the relation of y and C, Δ C/ Δ y becomes definite value, and according to (formula 5), the relation of alternating voltage and exciting force can be used as linearity and handles.

Secondly, the production process of in Figure 18 A～Figure 18 D, representing the mechanical resonator of present embodiment shown in Figure 1.

Vibrating body and electrode form on substrate 10.For example substrate 10 is high impedance silicon substrates of piling up the silicon nitride film of the silicon oxide layer of thermal oxidation and the CVD method that reduces pressure from the teeth outwards.

At first, spinning covers the sacrifice layer of being made up of photoresist on substrate 10, after exposure, the development, dries on heating plate, forms sacrifice layer 11 (Figure 18 A).

Secondly, on the whole surface of substrate, pile up aluminium 12 (Figure 18 B) by sputter.

Then, by on aluminium, forming photoresist,, the figure of being made up of described photoresist is carried out the dry ecthing of aluminium as mask, form vibrating body 13 and electrode 14 (Figure 18 C) with the photoetching process figure of stamping.At this moment, the shape of the face that electrode 14 and vibrating body 13 are relative is made the curve by (formula 4) expression.This can realize by the curve of the figure on the mask that uses being made usefulness (formula 4) expression in photoetching process.

And then, remove figure and the sacrifice layer of forming by photoresist 11 with oxygen plasma.Thus, vibrating body 13 becomes vibratile double bracing beam, in addition and 14 formation capacitors of electrode (Figure 18 D).The vibration of vibrating body 13 can be taken place by the electrostatic force of 14 at vibrating body 13 and electrode.The relative substrate of the direction of vibration of this occasion vibrating body 13 becomes horizontal direction.

In addition, present embodiment is used the high impedance silicon substrate, but also can use general silicon substrate, compound semiconductor substrate and insulating material substrate.

In addition, on high impedance silicon substrate 10, form silicon oxide layer and silicon nitride film, but, also can omit the formation of these dielectric films in the sufficiently high occasion of the impedance of substrate as dielectric film.

In addition, present embodiment is as the material that forms vibrating body and electrode, used aluminium, but also can use other metal material Mo, Ti, Au, Cu and the high concentration ground semi-conducting material that imports impurity, as amorphous silicon, have the macromolecular material of conductivity etc.And, use sputtering method as film build method, but also can use CVD method, galvanoplastic etc.

In the present embodiment, vibrating body is made the double bracing beam, but identical with the model shape of cantilever beam owing to also the surface configuration of electrode being made for cantilever beam, so can obtain equally | and Δ C/ Δ y| becomes big effect.

Below the mechanical resonator of vibrating body being made the cantilever beam occasion is described.

Figure 19 is a schematic diagram of vibrating body being made the mechanical resonator of cantilever beam occasion.Vibrating body 21 is the fixing cantilever beams of a single face, and thickness is h, the wide W of being, the long L of being.Electrode 22 is provided with near vibrating body 21, and it is the insulating barrier 23 of d that thickness is set from the teeth outwards.With the occasion of first resonance pattern exciting cantilever beam, the surface configuration of electrode 22 is as shown in the formula setting.

$y\left(x\right)=-{\mathrm{\&delta;}}_{\max }\left[\frac{1}{2}\right\{\cosh \mathrm{kx}-\cos \mathrm{kx}-0.734096(\sinh \mathrm{kx}-\sin \mathrm{kx})\left\}\right]-d$

$k=\frac{1.875104}{L}$

In addition, the double bracing beam of embodiments of the present invention or the vibration mode of cantilever beam are a pattern of transverse vibration, even but to secondary or above higher modes, because the surface configuration of electrode is made the resonance mode waveform of vibrating body, and so also can obtain | Δ C/ Δ y| becomes big effect.

The block curve that Figure 20 A describes on the xy plane is represented the quadratic modes waveform of the transverse vibration of cantilever beam.Be that length is that the cantilever beam of L has a node from stiff end 0.774L place.At this moment, if traverse whole length L, the surface configuration of electrode is made waveform under the resonance mode, then since behind the node resonance of the beam of free end hindered by electrode, shown in Figure 20 B, electrode is controlled at length from the stiff end to the node.

In addition, in addition, shown in Figure 20 C, configured electrodes also can be received same effect on the position from node to free-ended length.Perhaps shown in Figure 20 D,, for example, also can be the electrode 22a exciting that is used for vibrating body 21, the detection that electrode 22b is used for the vibration of vibrating body 21 across vibrating body, the electrode 22 of allocation plan 20B and Figure 20 C respectively.

According to above-mentioned present embodiment, because by the electrode surface shape being made the shape of vibrating body resonance mode, the capacitance variations of per unit displacement of carrying out the vibrating body of synchronous vibration becomes maximum, thereby can convert the electrical signal to mechanical oscillation efficiently or efficiently mechanical oscillation be converted to the signal of telecommunication.And the electrode surface shape needn't be in full accord with the shape of the resonance mode of vibrating body, and is approaching more with its shape, and available effect is just good more.

In addition, by on cantilever beam, install as described above exciting with and detect the electrode of usefulness, can realize the mechanical oscillation filter of the good and miniaturization of conversion efficiency.

(execution mode 2)

Fig. 6 is the example that the mechanical resonator of Fig. 1 is used for machinery → electric transducer.

In Fig. 6, carry out at the y direction of principal axis transverse vibration vibrating body 1 displacement as and the variation of the capacitor C of 2 at electrode be detected.The current i that flows through as shown in the formula, with the product representation of vibration velocity and Δ C/ Δ y.

$i=\frac{\mathrm{dq}}{\mathrm{dt}}\&cong;\frac{\mathrm{dC}}{\mathrm{dy}}\frac{\mathrm{dy}}{\mathrm{dt}}V---\left(6\right)$

If use Δ C/ Δ y to be counted as being roughly the displacement region of definite value, the displacement signal of beam is reproduced by integrator 601 by current signal, at this moment | and y| is big more for Δ C/ Δ, can obtain big current signal more.The same with Fig. 2, when supposing d=0.1 μ m, ε r=1, δ max=1 μ m, L=40 μ m, W=20 μ m, it is big to adopt the structure of the present invention represented with Fig. 4 can obtain the existing parallel plate structure represented than Fig. 3 | Δ C/ Δ y|.Therefore, the machinery → electric transducer of present embodiment can convert faint vibration to the signal of telecommunication efficiently.

(execution mode 3)

Fig. 7 is to use the mechanical oscillation Filter Structures figure of the mechanical resonator of present embodiment.

In Fig. 7, the mechanical oscillation filter has electrode as the shape of embodiment of the present invention 1 and 2, the resonance mode represented for the capacitive coupling part of the incoming line 104 of the electricity → mechanical switch portion of the filter construction represented at Figure 22 and double bracing beam 101 and for the capacitive coupling part both sides use of the incoming line 105 of machinery → electric converter section and double bracing beam 102 in Fig. 1.And then, it is a plurality of by one group of electricity → mechanical switch portion and filter that machinery → electric converter section is formed that this mechanical oscillation filter is made configuration arranged side by side, input voltage is imported along separate routes and to each filter, and the output current signal of each filter is unified the structure of taking-up.By the number of so suitable adjustment filter, can reduce especially becomes reflected signal problem, that impedance does not match and produces in high-frequency circuit, can become mechanical oscillation to electrical signal conversion efficiently, and mechanical oscillation are re-used as signal of telecommunication taking-up.

Below, the example of a plurality of filters of expression configured in series.

Fig. 8 is the vertical view of girder construction, is the structure that beam sides a1, a2, b1, b2, c1, c2 portion six places are fixed as stationary plane.According to this structure and long for L, widely be the connect structure equivalence roughly of formation of two double bracing beams of W.This is because any double bracing vibration of beam by passing to another double bracing beam between stationary plane b1, the b2, is played in conjunction with beam action between this stationary plane b1, the b2.

Fig. 9 is to use the mechanical oscillation Filter Structures figure of the mechanical resonator of described girder construction.

In Fig. 9, a double bracing beam of girder construction shown in Figure 8 101 and have incoming line 104 capacitive coupling of the electrode structure of the present invention that Fig. 1 represents, another double bracing beam 102 and have outlet line 105 capacitive coupling of the electrode structure of Fig. 1.And then the mechanical oscillation filter of making this girder construction forms a plurality of Filter Structures of configured in series.Like this, can obtain the impedance matching that is connected in series at an easy rate by the girder construction that adopts Fig. 8.And then, because the such very weak structure of superfine shock resistance of the bondbeam 103 of Figure 22 needn't be set,, improve the rate of finished products of manufacturing so also can improve intensity.

(execution mode 4)

Figure 10 is different with the filter construction of the Figure 22 that has electricity → mechanical transducer and machinery → electric transducer respectively, is to have the mechanical oscillation filter of realizing the mechanical resonator structure of two kinds of functions with a vibrating body.Particularly, the common structure of both sides of the machinery → electric transducer shown in Figure 6 of the electricity → mechanical transducer shown in Figure 2 of the total execution mode 1 of present embodiment and execution mode 2.This structure is speciality with simple in structure, but is following by the capacitance variations of the displacement of the vibrating body 1 of input signal vi exciting and beyond the alternating current that takes place, the stable unwanted alternating current that capacitance is sewed that passes through takes place also.Promptly in Fig. 4, when exchanging operating point and for example be y=0, the electric capacity during as if y=0 is big, then also can flow through not to be the unwanted alternating current that caused by exciting so the function reduction of filter.Thereby, although expectation | Δ C/ Δ y| greatly is as described in the execution mode 1,2, must reduce the value of C as far as possible.

Therefore, present embodiment as shown in figure 11, the structure that mechanical resonator is made is also 1 the same with vibrating body with vibrating body 1 electrode of opposite 2, vibrate with the resonance mode of resonance frequency, and the 1/2 ground setting of only staggering pattern standing wave wavelength of relative position.At this owing to use the first resonance pattern, so make electrode 2 the x direction only stagger beam length L 1/2.

This mechanical resonator is a mechanical oscillation filter of making execution mode 3 described parallel-connection structures, only illustrates the part to the reciprocating structure of x direction in Figure 11 A.In addition, the vibrational state of expression vibrating body 1 and electrode 2 in Figure 11 B.At this, represent the relation of the condenser capacitance C of vibration displacement y and every length L with 403 of Fig. 4.The state of Figure 11 A, promptly during vibration displacement y=0, capacitor C can adopt the value little with the parallel plate structure same degree of Fig. 3.In addition, in Figure 11 B of expression resonance state, electric capacity is very near the electric capacity between contiguous electric conductor, the i.e. electric capacity of Fig. 2 described in embodiment of the present invention 1 and the execution mode 2 and the structure among Fig. 6.The result is when y=0, | Δ C/ Δ y|=6.3 * 10 ^-9[F/m], bigger than the value of existing parallel plate structure shown in Figure 3, approach the value of the structure of Fig. 2 and Fig. 6.Thereby, by in the mechanical oscillation filter of Figure 10, using the structure of Figure 11, can lower unwanted alternating current, and can constitute | the big filter efficiently of value of Δ C/ Δ y|.

503 of Fig. 5 is y-C characteristics of the occasion of δ max=0.3 μ m.Show in Fig. 5: the electrostatic capacitance C of the mechanical resonator of the structure with Figure 11 during y=0 is the same with existing parallel plate structure shown in Figure 3 little, and | Δ C/ Δ y| can reach big equally with the structure of Fig. 2, Fig. 6

Therefore, the mechanical resonator of present embodiment can diminish the electrostatic capacitance of the displacement hour of vibrating body with simple structure; The electrostatic capacitance of vibrating body when the resonance mode bottom offset is big becomes big.Therefore, can reduce unwanted alternating current, and the signal of telecommunication is converted to mechanical oscillation efficiently or converts mechanical oscillation to the signal of telecommunication efficiently.In addition, the mechanical oscillation filter that uses this mechanical resonator can be realized the mechanical oscillation filter of good conversion efficiency and miniaturization by the electrode of exciting and detection usefulness is installed on the double bracing beam.

Figure 21 A～Figure 21 D is that expression is shown in Figure 11, the figure of the manufacturing process of the mechanical resonator of present embodiment.

In Figure 21 A～Figure 21 D, on substrate 10, form vibrating body.For example substrate 10 is to pile up the silicon oxide layer that produced by thermal oxidation from the teeth outwards and with the high impedance silicon substrate of the nitride film of decompression CVD method generation.

At first spinning covers the layer that is made of photoresist on substrate 10, after exposure, the development, dries on heating plate, forms sacrifice layer 11 (Figure 21 A).At this moment, on sacrifice layer 11, form minute aperture 15a and the 15b that arranges with certain spacing. Minute aperture 15a, 15b form on the position of 1/2 spacing of staggering mutually as shown in the figure.

Secondly, on the whole surface of substrate, pile up aluminium 12 (Figure 21 B) by sputter.At this moment, aluminium 12 also is embedded in the minute aperture 15.

Then, on aluminium, form photoresist, with the photoetching process figure of stamping.Afterwards, the figure that is made of described photoresist is carried out the dry ecthing of aluminium as mask, form vibrating body 13a and vibrating body 13b (Figure 21 C).At this moment, on minute aperture 15a, form vibrating body 13a, on minute aperture 15b, form vibrating body 13b.

And then, remove figure and the sacrifice layer 11 that constitutes by photoresist with oxygen plasma.Thus, vibrating body 13 becomes vibratile beam.In addition, because vibrating body 13 is fixed on the substrate 10 by the aluminium fixture 16 that is embedded in minute aperture 15, become the structure that fixture 16 is constituted continuously as the double bracing beam of stiff end.Can realize the mechanical resonator structure of Figure 11 thus.And in this occasion, the relative substrate of the direction of vibration of vibrating body 13 becomes horizontal direction.

In addition, use the high impedance silicon substrate in the present embodiment, but also can use general silicon substrate, compound semiconductor substrate and insulating material substrate etc.

In addition, on high impedance silicon substrate 10, form silicon oxide layer and silicon nitride film, but, also can omit the formation of these dielectric films in the sufficiently high occasion of the impedance of substrate as dielectric film.

In addition, in the present embodiment, used aluminium, but also can use other metal material Mo, Ti, Au, Cu and high concentration ground to import the semi-conducting material of impurity, as amorphous silicon, have the macromolecular material of conductivity etc. as the material that forms beam.And then, use sputtering method as film build method, but also can use CVD method, galvanoplastic etc.

(execution mode 5)

Present embodiment is identical with execution mode 4 purposes, relates to being used to suppress not need the alternating current that takes place to make every effort to reduce the method for the condenser capacitance of mechanical resonator.Figure 12 is the structure chart of the mechanical resonator of present embodiment.

In Figure 12,121 electric conductor from the two ends of electrode 2 the length of Δ L part is replaced as insulator, and this point is different with the structure of Fig. 1.

Figure 13 is that expression is the performance plot of Δ L/L as the relation of the vibration displacement y of the occasion of parameter and electrostatic capacitance C.Here, establish d=0.1 μ m, ε r=1, δ max=1 μ m, L=40 μ m, W=20 μ m.

The insulation division at the two ends of electrode is many more, and promptly Δ L/L is big more, can reduce electrostatic capacitance C more.And this moment | Δ C/ Δ y| also reduces, in addition move closer in the figure as with reference to shown in existing parallel plate structure shown in Figure 3 | the value of Δ C/ Δ y|.The reduction of electrostatic capacitance C and | there is the relation of compromise selection in the increase of Δ C/ Δ y|, can select to be fit to service condition, optimum y-C characteristic therein.

We can say: to by above like that, the two ends of electrode changed into the effect that insulator receives in other words be exactly, in order to make | y| is bigger than the occasion of the structure of making existing parallel plate-type for Δ C/ Δ, may not need to connect the electrode that total length L, configuration surface are shaped as the waveform of resonance mode, a part is that the waveform of resonance mode also can be received same effect in the total length.

And thus, the mechanical resonator of present embodiment is owing to can diminish the electrostatic capacitance of the displacement hour of vibrating body with simple structure; Vibrating body is a resonance mode, the electrostatic capacitance when displacement is big becomes big, therefore, can reduce unwanted alternating current, and the signal of telecommunication is converted to mechanical oscillation efficiently or converts mechanical oscillation to the signal of telecommunication efficiently.

(execution mode 6)

Present embodiment relates to the non-linear method of the relation of the vibration displacement y that improves vibrating body and electrostatic capacitance C.Even observe the relation of y and C shown in Figure 4, then compare with existing parallel plate structure shown in Figure 3, the electrode of waveform shape that has the resonance mode of Fig. 2 and Fig. 6 by use, though improved to the index of electromechanical conversion efficiency | Δ C/ Δ y|, but the minus side displacement of vibrating body, non-linear when promptly vibrating body is near the electrode side becomes remarkable.Thereby, in (formula 5), (formula 6), be difficult to Δ C/ Δ y is regarded as constant, thus the performance that concerns the complexity that right and wrong are linear between voltage and power, displacement and electric current.

Figure 14 is the structure chart of the mechanical resonator of present embodiment.In Figure 14, the electric conductor of the part of the length from the central part of electrode 2 along the both sides Δ L of x direction is replaced as insulator, this point is different with the structure of Fig. 1.

Figure 15 is that expression is the performance plot of Δ L/L as the relation of the vibration displacement y of the occasion of parameter and electrostatic capacitance C.Here, establish d=0.1 μ m, ε r=1, δ max=1 μ m, L=40 μ m, W=20 μ m.

Many more from the insulator part 141 of the center Δ L of electrode, promptly Δ L/L is big more, non-linear in the time of suppressing vibrating body 1 near electrode 2 more.And this moment, because | Δ C/ Δ y| descends, and by both compromise selection, can obtain meeting the optimum y-C characteristic of service condition.

We can say, to in other words being exactly by as above, electrode centers portion being changed into the effect that insulator receives, in order to make | y| is bigger than the occasion of the structure of making existing parallel plate-type for Δ C/ Δ, the electrode that total length L, configuration surface are shaped as the waveform of resonance mode may not be needed to connect, also same effect can be received even the part in the total length is the waveform of resonance mode.

And, thus, the mechanical resonator of present embodiment is owing to can diminish the static capacity of the displacement hour of vibrating body with simple structure, vibrating body is a resonance mode, the electrostatic capacitance when displacement is big becomes big, therefore, can reduce unwanted alternating current, and the signal of telecommunication is converted to mechanical oscillation efficiently or converts mechanical oscillation to the signal of telecommunication efficiently.And then the relation between the voltage of the mechanical resonator of present embodiment and power, displacement and electric current is more approaching linear, can control at an easy rate.

(execution mode 7)

Present embodiment relates to utilization by the electrode surface shape being made the waveform of resonance mode, even the input voltage low-voltage also can obtain the construction of switch of the large amplitude of vibrating body.

Figure 16 is the structure chart of the switch of present embodiment.

In Figure 16, as the 1st contact electrode, form contact 4a among near the insulating barrier 3a the central part of electrode 2, on insulating barrier 3a, expose its surface.And central part also forms contact 4b by insulating barrier 3b as the 2nd contact electrode below vibrating body 1, applies Dc bias Vb and alternating voltage Vi at vibrating body 1 and 2 at electrode.It is different with the structure of the mechanical resonator of execution mode 6 to have these contacts 4a, 4b.

General switch only applies direct voltage Vb without alternating voltage Vi and comes vibrating body 1 is applied electrostatic force.As long as Vb surpasses absorption voltage, electrostatic force is preponderated than the spring recuperability of vibrating body 1, and vibrating body 1 is inhaled poly-sharp to electrode direction, contact 4a, 4b closure.But, be necessary for high-pressure generating circuit because absorption voltage is generally the high pressure of tens of～hundreds of volts.

To this, the alternating voltage Vi exciting vibrating body 1 of the switch of present embodiment with the resonance frequency same frequency of vibrating body 1.Since the vibration displacement of vibrating body of this moment also reach apply equal quiet electrostatic force the time Q value doubly, so near the vibrating body 1 easy arrival insulating barrier 3a, after this use bias voltage Vb with vibrating body 1 to electrode 2 Electrostatic Absorption.In addition, in the present embodiment,, place it in the shell and, do one's utmost to get rid of because the attenuating that the viscosity of air produces to vibrating body with environment vacuum seal for improving the purpose of Q value.

More than because by making structure of the present invention, can improve from the conversion efficiency of the signal of telecommunication, thereby obtain big synchronous vibration to mechanical signal, the vibrating body of resonance state is contacted with electrode, can realize construction of switch with the electrostatic force maintenance.

(execution mode 8)

Figure 17 is the detail drawing of the insulating barrier 3 on the electrode 2 of switch of the present invention, and it is the state that the polyfurolresin particle 5 of 1 μ m forms on electrode with individual layer with electroless plating film 6 that expression makes particle diameter.By form the resin particle of particle diameter unanimity like this with individual layer, can keep the thickness of insulating barrier certain, and utilize the lubrification of polyfurolresin,, also can reduce the out of contior absorption affinity that is called as stiction even vibrating body contacts with polyfurolresin particle 5.

The possibility of utilizing on the industry

Above-mentioned the present invention is useful to mechanical oscillation wave filter or the switch that uses mechanical resonator, and is suitable The miniaturization that should install and high performance.

Claims (18)

1. a mechanical resonator is characterized in that,

Comprise the vibrating body that carries out mechanical resonance vibration and when synchronous vibration described vibrating body near and on the amplitude direction of described synchronous vibration, be bent the electrode of configuration.

2. mechanical resonator as claimed in claim 1 is characterized in that,

Shape when the surface configuration of the electrode of described bending is out of shape with resonance mode with described vibrating body is identical.

3. mechanical resonator as claimed in claim 1 or 2 is characterized in that,

The surface area of the described vibrating body of surface area ratio of the described electrode relative with described vibrating body is little.

4. mechanical resonator as claimed in claim 3 is characterized in that,

With when resonance the amplitude part that becomes maximum described vibrating body with and near do not dispose described electrode on the relative position.

5. mechanical resonator as claimed in claim 3 is characterized in that,

On the position relative, do not dispose described electrode with the end of described vibrating body.

6. a mechanical resonator is characterized in that,

Comprise the vibrating body that carries out mechanical resonance vibration with near described resonance body and the electrode that vibrates with the resonance mode of identical resonance frequency.

7. as each described mechanical resonator in the claim 1 to 6, it is characterized in that,

Also have the grid bias power supply that is connected and between them, produces electrostatic field with described vibrating body and described electrode,

When receiving the change in voltage of resonance frequency between described vibrating body and described electrode, described vibrating body carries out synchronous vibration.

8. as each described mechanical resonator in the claim 1 to 6, it is characterized in that,

Also have the test section that comes detection signal according to the change in voltage between described electrode and the described vibrating body,

Described vibrating body when vibrating by described vibrating body and the electrostatic capacitance change between the described electrode, described test section detects the signal that converts the signal of telecommunication from vibration to.

9. as each described mechanical resonator in the claim 1 to 8, it is characterized in that,

On at least one side of described electrode and the described vibrating body face relative, insulating barrier is set with described electrode.

10. mechanical resonator as claimed in claim 9 is characterized in that,

Described insulating barrier is the macromolecule particle with insulating properties and lubrification.

11. as each described mechanical resonator in the claim 1 to 5, it is characterized in that,

Also be included on the surface of the described vibrating body relative with described electrode with the 1st contact electrode of described vibrating body insulation configuration and with the chimeric ground of described the 1st contact electrode, with the 2nd electrode of described electrode insulation configuration.

12. mechanical resonator as claimed in claim 11 is characterized in that,

Also have the grid bias power supply that is connected and between them, produces electrostatic field with described vibrating body and described electrode,

When receiving change in voltage between described vibrating body and described electrode, described vibrating body carries out synchronous vibration, described the 1st contact electrode during near described the 2nd contact electrode the voltage with described grid bias power supply carry out Electrostatic Absorption.

13. a mechanical resonance apparatus is characterized in that,

Electricity configuration in parallel is a plurality of as claim 7 or 8 described mechanical resonators.

14. a mechanical resonance apparatus is characterized in that,

The electricity configured in series is a plurality of as claim 7 or 8 described mechanical resonators.

15. a mechanical resonance apparatus is characterized in that,

To be placed in the vacuum-packed shell of environment as each described mechanical resonator in the claim 1 to 14.

16. a filter is characterized in that,

Use as each described mechanical resonator in the claim 1 to 10.

17. a switch is characterized in that,

Use as claim 11 or 12 described mechanical resonators.

18. a circuit is characterized in that,

Use as each described mechanical resonator in the claim 1 to 15.

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