CN102857192B - Micro-mechanical harmonic oscillator with adjustable gap between electrode and vibrating disk - Google Patents

Abstract

The invention provides a micro-mechanical harmonic oscillator with an adjustable gap between an electrode and a vibrating disk, and belongs to the technical field of RF communication and micro-electromechanical systems (MEMS). The oscillator comprises a substrate, a vibrating disk arranged on the substrate, an annular-piece AC input electrode, an annular-piece AC output electrode and joints on both sides of the vibrating disk, a static electrode with a positioning head, insulating pieces on both end surfaces, and an input and output electrode movable positioning assembly comprising an electrode rod, an electrode arm and an elastic guiding arm. According to the invention, because the static electrode with a positioning head and the input and output electrode movable positioning assembly are additionally arranged on the substrate, the gap (Electrified Gap) among the input and output electrodes and the vibrating disk in working can be controlled at about 10nm and a wedge-shape intermittence cannot be formed, so that the micro-mechanical harmonic oscillator with an adjustable gap between an electrode and a vibrating disk has the characteristics that the gap between the input and output electrodes and the vibrating disk in working and the dynamic resistance of the disk harmonic oscillator in working can be effectively reduced, the Q value of the harmonic oscillator is high, the performance of the harmonic oscillator is outstanding.

Description

The adjustable micromechanical resonator of a kind of electrode and vibrating disk gap

Technical field

The invention belongs to the components and parts technical field in radio communication and MEMS (micro electro mechanical system) (MEMS) technical field, particularly relate to a kind of input, MEMS resonator that gap dynamic between output electrode and vibrating disk regulates.

Background technology

Micromechanical disk resonator (Micromechanical Disk Resonator), be called for short MEMS disk resonator) be in recent years just at a kind of rf-resonator of fast development, can be widely used in the radio circuit such as oscillator, filter.MEMS disk resonator small size, the high Q ratio of power consumption (energy storage with) value, low-power consumption, the advantage such as easy of integration, make it have huge advantage and prospect when comparing mutually with traditional resonator.In disk resonator, input, distance between output electrode and vibrating disk and overlapping area directly decide the dynamic electric resistor of resonator, thus directly affect resonator q and power consumption.But the effect of adjustment overlapping area can not show a candle to the successful of adjusting play, because the series motional resistance R of MEMS disk resonator _xdetermined by following formula:

$R_x=\frac{{\mathrm{\ω}}_0{m}_{\mathrm{re}}}{Q}\frac{1}{{V_p}^2}\frac{{d_0}^4}{{\mathrm{\φ}}_1{\mathrm{\φ}}_2{\left({\mathrm{\ϵ}}_0\mathrm{Rt}\right)}^2}$

I.e. dynamic electric resistor R _xvalue is with input, gap (d between output electrode and vibrating disk ₀) biquadratic be directly proportional, therefore reduce the gap width d between disk and input and output electrode ₀significantly can reduce the dynamic electric resistor R of disk resonator _x.In above formula: ω ₀radial contour modal resonance angular frequency, m _rerepresent disk quality, Q represents the resonance frequency of resonator, V _prepresent the bias voltage of disk, d ₀represent the gap width between disk and input and output electrode, φ ₁, φ ₂represent radian inside input electrode and output electrode respectively, ε ₀represent the relative dielectric constant of air, R represents the radius of vibrating disk, and t represents the thickness of vibrating disk.

And increase the increase that overlapping area can bring disk quality, the resonance frequency of resonator can be made like this to decline.Therefore, the distance reduced between disk and electrode becomes and a kind ofly reduces resonator dynamic electric resistor thus improve the most effective approach of resonator q.In MEMS resonator technique, the most narrow slot width using the methods such as common photoetching, etching to obtain is about 100nm, and dynamic electric resistor is at 2.6k about Ω.People such as Nguyen in 2009 with atomic layer deposition system (atomic layer deposition), by deposit dielectrics between electrode and disk, achieve the adjustment in gap, gap is shortened to 32nm.After this Cornell University also uses same instrument at electrode deposited inside hafnium oxide, obtains the gap of 10nm; But the equipment fetch long price of atomic layer deposition system, the cost of manufacture of resonator are high.Publication number be CN102280682A, name is called in the patent document of " a kind of micromechanical disk resonator " and discloses a kind of vibrating disk comprising substrate, be located at on-chip band direct current biasing wire, the ring plate formula ac input electrode being located at vibrating disk both sides with exchange output electrode, and a pair for input electrode and the fixed strip of output electrode location and the micromechanical disk resonator of a pair suspension type corrugated beams, this resonator by corrugated beams by being fixed on the on-chip fixed input of resonator in traditional micromechanical disk resonator, output electrode changes suspension type into, utilize DC offset voltage that electrode is pulled to vibrating disk, then by positioning strip, input, output electrode are fixed, but although this technology can improve the conversion efficiency of resonator to a certain extent, reduce the features such as production cost, but deposit require in process of production initial seam () gap between positioning strip and electrode should≤initial seam () gap between vibrating disk and electrode, and the narrowest width (100nm) that the gap width mentioned in this patent has been common technology can be reached, because though two primary clearances adopt same process to be processed into through photoetching (or etching) etc. simultaneously, if the initial chink between positioning strip and electrode is due to technique (photoetching, etching etc.) reason of precision is greater than initial chink between vibrating disk and electrode, input will be caused, output electrode not yet contacts with positioning strip, and input, output electrode and vibrating disk contact short circuit, resonator is caused to lose efficacy, and the inner side radian of the input of this technical requirement, output electrode must be greater than the radian of disk, this also will increase the dynamic electric resistor of resonator.Thus still to there is manufacture process requirement high for this technology, under existing common process condition, be difficult to reduce further the width in input, output electrode and vibrating disk gap, and input, radian inside output electrode and the inconsistent dynamic electric resistor caused of vibrating disk radian are higher, thus limit the disadvantages such as the further raising of resonator combination property.

Summary of the invention

The object of the invention is to count the defect existed background technology, the adjustable micromechanical resonator of a kind of electrode of Curve guide impeller and vibrating disk gap, to reach on the basis of the difficulty reducing resonator processing technology, effectively reduce input, gap between output electrode and vibrating disk and disk resonator work time dynamic electric resistor, improve the objects such as resonator q resonator performance.

Solution of the present invention is on the substrate of resonator, set up the electrostatic attraction electrode of one or two end band positioning head, simultaneously the running fix assembly that comprises electrode stem, horn and the elastic guide arm be attached thereto respectively is set in the rear end of input, output electrode, horn not only as the inputing or outputing of alternating current, but also as the lever arm of force of respective electrode movement; Elastic guide arm is symmetrically set in electrode stem both sides, has not only guaranteed that respective electrode moves along axis, but also can to have coordinated with horn and electrostatic attraction electrode head, made the suspended electrode formula after putting in place locate and maintain its operating state; The structure of vibrating disk and still identical with background technology with the annexation of substrate.Therefore, micromechanical resonator of the present invention comprises substrate, is located at on-chip vibrating disk, the ring plate formula ac input electrode being positioned at vibrating disk both sides with exchange output electrode and exchange input adapter, exchange out splice going splice, key be also to be provided with on substrate one or two end band positioning head electrostatic attraction electrode, be equipped with insulating trip at the end face of two positioning heads, and ac input electrode with exchange between input adapter, exchange and export and exchange the electrode running fix assembly being provided with respectively between out splice going splice and comprising electrode stem, horn and elastic guide arm, the electrostatic attraction electrode of two end band positioning heads is fixed on substrate, each insulating trip is then entirely fixed on the surface of positioning head, electrode running fix assembly by two electrode stems respectively with corresponding ac input electrode and exchange output electrode rear end and be fastenedly connected, and input electric connection respectively with corresponding interchange by one end of two horns and exchange and export electric connection and connect, the outer end of electrode stem is then fixedly connected with the middle part of respective electrode arm respectively, the other end of two horns is then suspended in just to the outside of electrostatic attraction electrode positioning head end face respectively, and and the distance that sets of insulating trip interval one on positioning head end face, the symmetrical centre of two elastic guide arms is fixedly connected with respectively with in the middle part of corresponding electrode stem, two ends are then respectively with corresponding support column and exchange and input electric connection, exchange and export electric connection connection.

Above-mentioned elastic guide arm is ripple arm.The outer end of described electrode stem is then fixedly connected with the middle part of respective electrode arm respectively, and its connecting portion is apart from stiff end 1/3rd or 1/2nd place in the middle part of horn.The distance that the insulating trip interval one of the other end then respectively and on positioning head end face of described two horns sets, being set as of its distance: insulating trip is spaced apart 3 times or 2.2 times of minimum clearance between two electrodes and vibrating disk on the other end of horn and positioning head end face when connecting portion distance electrode arm stiff end 1/3rd place or 1/2nd places of horn and electrode stem, under equal conditions.

The present invention owing to having set up the electrostatic attraction electrode of two end band positioning heads on substrate, the running fix assembly that one comprises electrode stem, horn and the elastic guide arm be attached thereto respectively is set in the rear end of input, output electrode simultaneously, horn not only as the inputing or outputing of alternating current, but also as the lever arm of force of respective electrode movement, initial gap on horn and positioning head end face between insulating trip is exaggerated by this lever arm of force exponentially, thus adopts the technique such as photoetching, etching to be easy to control its machining accuracy; Elastic guide arm is symmetrically set in electrode stem both sides, has not only guaranteed that respective electrode moves along axis, but also can to have coordinated with horn and electrostatic attraction electrode head, made the suspended electrode formula after putting in place locate and maintain its operating state.Gap (charged gap) when inputting, work between output electrode and vibrating disk can control can't form Wedge-shaped interval at about 10nm by the present invention, thus can prevent input, output electrode and vibrating disk contact short circuit.Thus to have the difficulty of resonator processing technology low in the present invention, can effectively reduce input, gap between output electrode and vibrating disk and disk resonator work time dynamic electric resistor, improve the features such as resonator q resonator performance.

Accompanying drawing explanation

Fig. 1 is resonator structure schematic diagram (vertical view) of the present invention;

Fig. 2 is A-A cutaway view (half sectional view).

In figure: 1. vibrating disk, 2.1. input electrode, 2.2. exchanges input adapter, 2.3,3.3:(ripple) elastic guide arm, 2.4,3.4: horn, 2.5,3.5: electrode stem, 2.6,3.6: support column, 3.1. output electrode, 3.2. exchanges out splice going splice, 4.1. electrostatic attraction electrode, 4.2. positioning head, 4.3. insulating trip, 5. point-like supporting, 6. substrate, 7. (after encapsulation) vacuum chamber.

Embodiment

Embodiment 1: the material of substrate 6 is silicon (length × wide × thick=25 μm × 18 μm × 5 μm); Vibrating disk 1 adopts polysilicon to make, and radius R is 1.9 μm, thickness is 1 μm, the distance of disk body bottom surface and substrate is 0.8 μm; Input, output electrode 2.1,3.1 are doped polycrystalline silicon, and the distance of each electrode and substrate is also 0.8 μm, thickness is 1 μm, and electrode inner arc radius of curvature R is 2 μm, and radian is л/2; Exchange input, out splice going splice 2.2,3.2 also doped polycrystalline silicon, (long × wide × high=4 μm × 3 μm × 1.8 μm); Input, output electrode arm 2.4,3.4 material are polysilicon, (long × wide × high=12 μm × 1 μm × 1 μm); Input, output electrode bar 2.5,3.5 adopt doped polycrystalline silicon to make, and width is 0.5 μm, and the distance from substrate is 0.8 μm, and thickness is 1 μm; And elastic guide arm 2.3,3.3 present embodiment adopt ripple arm, crest height of wave 2.5 μm, from the distance of substrate be 0.8 μm; Support column 2.6,3.6 (long × wide × high=3 μm × 2 μm × 1.8 μm), material polysilicon; Electrostatic attraction electrode 4.1 is doped polycrystalline silicon, (long × wide × high=4 μm × 2.5 μm × 1.8 μm), positioning head 4.2 be doped polycrystalline silicon, end face and insulating trip 4.3 mating part volume be (long × thick × high) 3 μm × 1 μm × 1.8 μm, insulating trip 4.3 adopts silicon dioxide, (long × thick × high) 3 μm × 0.1 μm × 1.8 μm), whole resonator adopts Vacuum Package.The present embodiment input, primary clearance between output electrode 2.1,3.1 and vibrating disk 1 are 100nm, input, initial distance between output electrode arm 2.4,3.4 and insulating trip 4.3 are 300nm, connecting portion distance electrode arm stiff end 1/3rd place of horn and electrode stem; In electrode running fix assembly, the coefficient of elasticity k of horn 2.4,3.4 and ripple elastic guide arm 2.3,3.3 is determined by following formula:

$k=16\mathrm{Ew}{\left(\frac{t}{l}\right)}^3$

Wherein, E is the Young's modulus of horn, and w is the width of horn, and t is the thickness of horn, and l is the length of horn.Present embodiment horn 2.4,3.4 coefficient of elasticity is k ₁=3950 μ N/ μm, draw the coefficient of elasticity k of ripple elastic guide arm 2.3,3.3 by Ansys emulation ₂=308 μ N/ μm, under present embodiment condition, ripple elastic guide arm 2.3,3.3 reversal interlocking relay (comparative electrode arm 2.4,3.4 thrust) of having of this ripple elastic guide arm 2.3,3.3 under work (charged) state can guarantee that the gap between vibrating disk 1 and input, output electrode 2.1,3.1 is 10nm.

The manufacture method of the present embodiment resonator:

The present embodiment adopts SOI (Silicon-On-Insulator, silicon in dielectric substrate) technique and in conjunction with the method for DRIE (deep reaction ion etching) and wet chemical etching technique, processes resonator.SOI substrate mainly comprises insulating substrate 6, (part that this layer is corroded forms vacuum chamber 7 to sacrifice layer silicon dioxide layer.Concrete processing method: first, deep reaction ion etching method is adopted to etch polysilicon layer, obtain involving vibrations disk 1, input electrode 2.1, exchange input adapter 2.2, input electrode arm 2.4, input electrode bar 2.5, ripple elastic guide arm 2.3, support column 2.6, output electrode 3.1, exchange out splice going splice 3.2, output electrode arm 3.4, output electrode bar 3.5, ripple, elastic guide arm 3.3, the structure sheaf of support column 3.6 (wherein, 2.2, 3.2, 2.6, 3.6, 4.1, 4.2 are connected with substrate by silicon dioxide layer, vibrating disk 1 is connected with substrate by point-like supporting 5, 2.1, 2.3, 2.4, 2.5, 3.1, 3.3, 3.4, 3.5 is structurally unsettled), then, adopt the method for wet chemical etching technique, with hydrofluoric acid by vibrating disk 1, silicon dioxide layer below input, output electrode 2.1,3.1 and electrode running fix assembly (2.3,2.4,2.5,3.3,3.4,3.5) erodes, make them unsettled, between vibrating disk and substrate, form cavity, finally by Vacuum Package, vacuumize after this cavity become vacuum chamber 7.

Embodiment 2: the present embodiment input, primary clearance between output electrode 2.1,3.1 and vibrating disk 1 are still connecting portion distance electrode arm stiff end 1/2nd place of 100nm, horn and electrode stem, input, initial distance between output electrode arm 2.4,3.4 and insulating trip 4.3 are 220nm, and all the other are all identical with embodiment 1; Also be 10nm in vibrating disk 1 under work (charged) state and input, gap between output electrode 2.1,3.1.

Claims (4)

1. the adjustable micromechanical resonator of an electrode and vibrating disk gap, comprise substrate, be located at on-chip vibrating disk, the ring plate formula ac input electrode being positioned at vibrating disk both sides with exchange output electrode and exchange input adapter, exchange out splice going splice, it is characterized in that the electrostatic attraction electrode being also provided with one or two end band positioning head on substrate, insulating trip is equipped with at the end face of two positioning heads, and ac input electrode with exchange between input adapter, exchange to export and comprise electrode stem with exchanging to be provided with respectively between out splice going splice, horn and elastic guide arm are at interior electrode running fix assembly, vibrating disk is fixed with substrate by the point-like supporting being located at this disk bottom center, the electrostatic attraction electrode of two end band positioning heads is fixed on substrate, each insulating trip is then entirely fixed on the surface of positioning head, electrode running fix assembly by two electrode stems respectively with corresponding ac input electrode and exchange output electrode rear end and be fastenedly connected, and input electric connection respectively with corresponding interchange by one end of two horns and exchange and export electric connection and connect, the outer end of electrode stem is then fixedly connected with the middle part of respective electrode arm respectively, the other end of two horns is then suspended in just to the outside of electrostatic attraction electrode positioning head end face respectively, and and the distance that sets of insulating trip interval one on positioning head end face, the symmetrical centre of two elastic guide arms is fixedly connected with respectively with in the middle part of corresponding electrode stem, two ends are then respectively with corresponding support column and exchange and input electric connection, exchange and export electric connection connection.

2., by the adjustable micromechanical resonator of electrode described in claim 1 and vibrating disk gap, it is characterized in that described elastic guide arm is ripple arm.

3. by the adjustable micromechanical resonator of electrode described in claim 1 and vibrating disk gap, it is characterized in that the outer end of described electrode stem is fixedly connected with the middle part of respective electrode arm respectively, its connecting portion is apart from corresponding ac input electrode and interchange output electrode 1/3rd or 1/2nd place in the middle part of horn.

4. by the adjustable micromechanical resonator of electrode described in claim 1 and vibrating disk gap, it is characterized in that the other end of described two horns be suspended in respectively just to the outside of electrostatic attraction electrode positioning head end face and and the distance that sets of insulating trip interval one on positioning head end face, being set as of its distance: insulating trip is spaced apart 3 times or 2.2 times of primary clearance between two electrodes and vibrating disk on the other end of horn and positioning head end face when connecting portion distance electrode arm stiff end 1/3rd place or 1/2nd places of horn and electrode stem, under equal conditions.