CN204231667U - A kind of silicon capacitor microphone - Google Patents
A kind of silicon capacitor microphone Download PDFInfo
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- CN204231667U CN204231667U CN201420697065.1U CN201420697065U CN204231667U CN 204231667 U CN204231667 U CN 204231667U CN 201420697065 U CN201420697065 U CN 201420697065U CN 204231667 U CN204231667 U CN 204231667U
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Abstract
The utility model provides a kind of silicon capacitor microphone, comprises substrate, vibrating diaphragm and backplane, and described substrate is provided with an operatic tunes; Described vibrating diaphragm is positioned at described operatic tunes top, produces mechanical oscillation when being excited by acoustic pressure wave; Be provided with fixing air gap between described backplane and described vibrating diaphragm, described vibrating diaphragm, described backplane and described air gap form capacitor jointly; Wherein, the middle part also comprising the one or more insulation be fixedly connected between described vibrating diaphragm and described backplane connects, and the middle part of described one or more insulation connects and described vibrating diaphragm is divided into multiple diaphragm element; And described backplane is flexible.The utility model under existing technological level, can improve the index such as sensitivity, the linearity, signal to noise ratio, sensitization capacitance, dynamic response of silicon capacitor microphone, widens the application scenario of product, increases product competitiveness.
Description
Technical field
The utility model relates to micro-microphone technical field, particularly a kind of silicon capacitor microphone of application flexibility backplane.
Background technology
Micro electronmechanical (MEMS micro-electro-mechanical system) microphone or claim silicon microphone because its volume is little, be suitable for the advantages such as surface mount and be widely used in the sound collection of tablet electronic device, such as: mobile phone, MP3, recording pen and monitoring equipment etc.In correlation technique, silicon capacitor microphone comprises substrate, back pole plate and vibrating diaphragm.Wherein, vibrating diaphragm is the core component of silicon capacitor microphone, both needed responsive sound pressure signal it is converted into the signal of telecommunication delicately, need again to blow at extraneous blast hit, retention normally works substantially unchangeably after the stress of dropping shock and inner processing technology release effect of stress.Its backplane is also different according to the manufacture craft realized, and is divided into rigidity backplane and flexible backplane.Vibrating diaphragm suffers restraints and comprises multiple connection and supporting form, determine the responsive vibration shape of vibrating diaphragm and suppress other not need the key technology of the vibration shape, directly relevant to the index such as sensitivity, the linearity, signal to noise ratio, pick-up voltage, sensitization capacitance, dynamic response of silicon capacitor microphone.
Traditional silicon micro-microphone is generally limited to construct multiple relative restraint between vibrating diaphragm and fixing rigid substrates and the static rigidity backplane of opposing substrate, this the way of restraint is due to substrate and rigidity backplane geo-stationary in sensitivity motion, design comparatively easy, but flexibility is also limited.
In traditional silicon micro-microphone design, existing research work has had realized that many optimal anchor direction of silicon microphone, but is limited to technique and rigidity backplane scheme, optimizes difficulty of getting up very large.
First, it is softer that existing research has realized that needs are made into edge vibrating diaphragm as far as possible, the middle harder structure close to lumped parameter capacity plate antenna model, but this point is when technique determines to realize under the prerequisite of vibrating diaphragm finite thickness, after encountering the increase of vibrating diaphragm area, the stiffness effect of non-edge from vibrating diaphragm center diaphragm itself, thus make to increase the contradiction that vibrating diaphragm area improves chip area utilance and lumped parameter capacity plate antenna model; In order to realize this point, partly vibrating diaphragm center is thickeied in US Patent No. 5146435; US Patent No. 5870482 reduces chip area utilance or on vibrating diaphragm, makes fold to make vibrating diaphragm local stiffened; Vibrating diaphragm is set to the higher material of resistivity and on vibrating diaphragm, covers the extremely low metal of a layer resistivity occur to be extracted by vibrating diaphragm displacement larger part useful signal by US Patent No. 7856804B2, avoids parasitic capacitance to cause decay and interference to signal; United States Patent (USP) 20110103622A1 then acts in a diametrically opposite way, and arranges the rigidity that fold reduces edge, to improve the relative ratio of vibrating diaphragm center diaphragm and edge's rigidity at vibrating diaphragm edge.These schemes in existing research all make up both contradictory relation by technologic improvement, all need make the change varied in size in technique, also the improvement varied in size can be made for such contradictory relation, but all inherently the reduction of this Resolving probiems------chip area utilance and technology difficulty the raising all meaning production cost cannot be promoted.On the other hand, inherently, limit the prerequisite of the vibrating diaphragm diaphragm thickness limit in process conditions or design condition under, by for the vibrating diaphragm of large-size, be mechanically connected, according to Saint Venant's principle, even if operatic tunes edge vibrating diaphragm periphery is all fixed because vibrating diaphragm only exists with the fixing base of operatic tunes edge or fixing backplane, still affect very micro-on vibrating diaphragm center rigidity, effectively cannot be adjusted the vibration shape by design means.
Secondly, the technical schemes such as US Patent No. 20070047746A1 attempt by by parallel for multiple microphone unit to obtain larger effective capacitance to ensure the quality of microphone signal, but this scheme is by the process technology limit of microphone processing itself, the invalid of microphone peripheral structure is directly proportional to microphone number, and the cost increase that correspondence is brought is difficult to overcome.
Again, when microphone chip size is done greatly to obtain effective capacitance, due to the restriction of process conditions, its residual stress causes the warpage of diaphragm.Usually, for the diaphragm structure of a hundreds of micron span, the warpage of central area 1-20 micron dimension can be there is, but the capacitance gap of microphone film (air gap) width range is generally all in 1-20 micron dimension.Therefore existing program is for this warpage issues, is all the warpage as far as possible being reduced vibrating diaphragm by various means, backplane is arranged harder in addition as far as possible, reduce the impact of warpage on electrical model of vibrating diaphragm and backplane.As Chinese patent CN1498513A suppresses warpage by making " convex microstructure ".Such technical scheme adds the difficulty that technique realizes, and the cost of corresponding increase is difficult to lower again, and is arranged by backplane more firmly can bring more crisp consequence, makes silicon microphone structure more easily cracked under impact.
Finally, for traditional silicon microphone products, if arrange fluting at diaphragm edge, the LF-response of microphone frequency response curve will decay, when decaying comparatively serious, even have influence on the normal response of microphone to frequency acoustic signals, thus affect it and normally use.And fluting is not set at diaphragm edge, mean for the rigid back electrode structure connected in the middle part of use many places, can only by arranging fold etc. on diaphragm, its local mechanical characteristic is limitedly set, effectively cannot apply " plate-girder combination " such classical mechanics structure to get the maximum optimization to make each diaphragm element structure, otherwise will difficult balance between mechanical property and LF-response decay.
To sum up, be necessary to provide a kind of novel organization plan retrained between vibrating diaphragm and flexible backplane for this problem, and for ensureing the substitutability of new construction scheme, the new departure provided need overcome or avoid the problems referred to above, and compatible to ensure lower cost with the typical production process of existing silicon microphone.Proposition of the present utility model, make with existing technological level can be implemented in polysilicon vibrating diaphragm and and its just right flexible backplane between mechanical connection is set neatly, by Appropriate application scale effect, make electrical model better, maintain sensor signal intensity with anti-interference, evade the even defective workmanship such as Appropriate application warping of membrane, further to improve the indexs such as sensitivity, the linearity, signal to noise ratio, sensitization capacitance, dynamic response.In other words, make high performance silicon capacitor microphone can also can low cost large-scale production under existing common processes level.
Summary of the invention
The purpose of this utility model is to provide a kind of silicon capacitor microphone of application flexibility backplane, the vibrating diaphragm vibration shape can be improved under existing technological level, evade the warping of membrane in technique, the unfavorable factors such as diaphragm is frangible, thus optimize the indexs such as sensitivity, the linearity, signal to noise ratio, sensitization capacitance, dynamic response.
For solving the problem, the technical solution adopted in the utility model is:
A kind of silicon capacitor microphone, comprises substrate, vibrating diaphragm and backplane; Described substrate is provided with an operatic tunes; Described vibrating diaphragm is positioned at described operatic tunes top, produces mechanical oscillation when being excited by acoustic pressure wave; Be provided with fixing air gap between described backplane and described vibrating diaphragm, described vibrating diaphragm, described backplane and described air gap form capacitor jointly; Wherein, the middle part also comprising the one or more insulation be fixedly connected between described vibrating diaphragm and described backplane connects, and described one or more middle part connects and described vibrating diaphragm is divided into multiple diaphragm element; Described backplane is flexible, and the natural frequency of vibration of described backplane is no more than 5 times of the natural frequency of vibration maximum of described diaphragm element.Affecting by processing technology, when having residual stress to cause the warpage of vibrating diaphragm and backplane, by arranging the method for flexible backplane, the warpage reducing vibrating diaphragm and backplane is on the impact of frequency response curve and microphone electrical model.Usually, the planar dimension of diaphragm is comparatively large and in technical scheme that gauge is less, adding man-hour with general technological level can due to the warpage of residual stress effect generation diaphragm itself.And it is comparatively large the planar dimension of diaphragm to be done large guarantee variable capacitance capacitance, diaphragm thickness is done its sensitivity of little guarantee higher, warpage issues makes to there occurs direct contradiction between the two.The utility model carrys out alternative single vibrating diaphragm by arranging the diaphragm element of polylith size difference within 50%, thus make every block diaphragm element area all less, its Local Phase is not serious to the warpage of the backplane part of its correspondence, leeway even can be had to be reduced to exchange higher sensitivity for by vibrating diaphragm thickness, and without the need to suppressing warpage by making " convex microstructure " as Chinese patent CN1498513A.Stress is released like this by arranging flexible backplane, make the Local warping at each unit place not obvious by multiple diaphragm element again, the desirability of electrical model when both ensure that silicon microphone normally works, again by becoming the feature of more flexible after flexible backplane release stress, ensure that reliability when silicon microphone is hit.
In addition, the natural frequency of vibration of described backplane, lower than the natural frequency of vibration of a certain diaphragm element, also can be equal to or greater than the natural frequency of vibration of a certain diaphragm element, but be no more than 5 times of the natural frequency of vibration maximum of each diaphragm element.The natural frequency of vibration of backplane is decided by the rigidity of backplane, if its natural frequency of vibration is lower than microphone works frequency range (being generally audiorange 20-20kHz), then can in input audio signal frequency close to making silicon microphone cannot with correct phase response input signal during its natural frequency of vibration, therefore the natural frequency of vibration of general backplane is all higher than microphone works frequency, say that the natural frequency of vibration of backplane can lower than the natural frequency of vibration of a certain diaphragm element herein, its reason is that after diaphragm element size reduces, the natural frequency of vibration increases, the natural frequency of vibration of backplane is exceeded after allowing the diaphragm element natural frequency of vibration to improve, be the flexible backplane design of the utility model key--although the diaphragm element natural frequency of vibration is high, in local, its rigidity is still much soft than the local of backplane, it is the main sensitivity contribution sources of response voice signal, and during 5 times of natural frequency of vibration maximum of the backplane natural frequency of vibration higher than each diaphragm element, just with the concept of rigidity backplane closely, when using technical solutions of the utility model, there is low cut and the more crisp and frangible integrity problem of backplane in the backplane of such setting.About the problem of " low cut ", introduction will be had below, about the problem of backplane " more crisp and frangible ", reason is the maximum ga(u)ge limiting backplane in technique or design, and under the prerequisite of the chip size decision backplane flat shape size of design, improving backplane rigidity only way is increase its tensile stress, although and the excessive raising that can bring backplane rigidity of tensile stress, also can bring the security risk of backplane " more crisp and frangible ".
Preferred silicon capacitor microphone, the material of wherein said vibrating diaphragm is doped polycrystalline silicon, is realized by the technique of deposit.As US Patent No. 7856804B2, vibrating diaphragm be set to high resistivity material and take out the method for the useful signal of telecommunication at signal sensitivity larger part by arranging layer of metal film, although the non-ideal factor impacts such as parasitic capacitance can be made in signal less, but because useful signal area is less, the signal of itself is fainter, signal to noise ratio is limited to, and technology difficulty and cost also rise a lot.The utility model is by being set to the mode of multiple diaphragm element by vibrating diaphragm, make that the edge of each diaphragm element is softer and center is harder, improve the efficiency of signal, thus extract useful signal without the need to more difficult by other, that cost is higher technique, only need be realized by the doped polycrystalline silicon technology of classics.
Preferred silicon capacitor microphone, wherein needs to carry out serial or parallel connection according to electrical lead wire between each diaphragm element, to form different capacitances.Described nonconducting middle part connects, and its upper and lower connects the vibrating diaphragm of conduction and the backplane of conduction respectively, so just can make to be connected between the diaphragm element of conduction; If need electric isolution between diaphragm element and geometry isolation, only need the border between diaphragm element arranges fluting, both can be separated from electricity with geometrically simultaneously; If need electric isolution between diaphragm element and geometry connection, only need the border between diaphragm element arranges the common reverse dense doping of integrated circuit technology, the mode namely by PN junction isolation ensures its electric insulation and remains geometric to be interconnected.
Preferred silicon capacitor microphone, between each diaphragm element between two area difference all within 50%, thus can ensure process deviation on the impact of each several part unit yardstick evenly, make the homogeneity between each diaphragm element stronger.
Preferred silicon capacitor microphone, wherein arranges fluting at diaphragm element edge, and its width range is at 0.1-10 micron.In traditional silicon capacitor microphone technology, because low-frequency sound wave penetration power is strong, if arrange fluting on diaphragm element, then there will be the problem of obvious microphone dynamic response low cut, if and on diaphragm element, do not arrange fluting apply " plate-girder combination " so typical mechanical structure, by means of only arranging the means such as fold, be difficult to reach optimum mechanics optimization effect.The warping of membrane phenomenon that the utility model utilizes technique itself to exist, by arranging warping of membrane direction and degree suppresses low cut problem.Its essential idea utilizes the principle that flexible membrane warpage is large and rigid membrance warpage is little, reduces from the distance made geometrically between several sections of string of a musical instrument end points that circular arc is isometric than before warpage.
Or silicon capacitor microphone of the present utility model also can arrange reverse dense doping on the border of described diaphragm element, makes the mode of being isolated by PN junction between each diaphragm element keep electric insulation and maintains the connection on space structure.
Preferred Electret Condencer Microphone, wherein only arrange on substrate the fixing anchor district of backplane, and vibrating diaphragm is suspended on backplane by means of only the connection of described middle part, there is not the annexation in mechanical support meaning with substrate.The mechanical connection between outer vibrating diaphragm and substrate is needed to remove by except lead-in wire, contribute to by after flexible backplane release stress, minimizing technique residual stress is delivered on diaphragm and disturbs its normal operating conditions as far as possible, thus is conducive to ensureing that the work of vibrating diaphragm is closer to ideal state.In traditional design in the past, vibrating diaphragm must be connected with arranging between substrate, because in rigidity backplane technical scheme, faces and only arranges middle part and connect the double-barreled question with low cut.The utility model, owing to adopting flexible backplane technical scheme, effectively controls low cut problem, thus vibrating diaphragm can be avoided to be connected with the direct of substrate by arranging middle portion connecting structure, thus avoids substrate stress on the uncontrollable impact of vibrating diaphragm.
Preferred silicon capacitor microphone, wherein has identical or in functional relation the natural frequency of vibration between each diaphragm element.Such as, the natural frequency of vibration between each diaphragm element can be arranged ordering (comprises several unit one group, the often situation of ordering between group), make it reach designing requirement by the indicators of overall performance of silicon microphone after the connection in series-parallel relation collaborative work pre-set; Single or part diaphragm element signal is fainter time, also the optimum configurations between each diaphragm element can be obtained identical, its complete parallel connection is obtained stronger sensor signal.
Preferred silicon capacitor microphone, wherein said diaphragm element shape is equilateral triangle, rectangle, orthohexagonal one.As everyone knows, in planar figure, can the simple graph of unlimited continuation be exactly triangle (comprising equilateral triangle and right-angled triangle), quadrangle (comprising rectangle, parallelogram and right-angled trapezium), regular hexagon, and comparatively conventional during setting unit be equilateral triangle, rectangle and regular hexagon.If need each diaphragm element natural frequency of vibration to arrange ordering or identical time, its shape is arranged to obtain the just the same non-ideal factor impact reducing technological fluctuation and bring, and use can the shape of unlimited continuation, good chip area utilance can be obtained.
Compared with prior art, the beneficial effects of the utility model are:
The utility model can under existing technological level, improve the index such as sensitivity, the linearity, signal to noise ratio, sensitization capacitance, dynamic response of silicon capacitor microphone, thus keeping enhancing product performance in the substantially constant basis of production efficiency, reliability, yield and cost, widen the application scenario of product, increase product competitiveness.
Accompanying drawing explanation
Fig. 1 is the cross-sectional schematic of the microphone conductive polycrystalline silicon diaphragm structure of prior art and the responsive deformation of backplane.
Fig. 2 is the cross-sectional schematic of the responsive deformation of application microphone conductive polycrystalline silicon diaphragm structure of the present utility model and backplane;
Fig. 3 is the schematic top plan view of a kind of middle part connection arrangement of the utility model preferred embodiment;
Fig. 4 is the schematic top plan view of the another kind of middle part connection arrangement of the utility model preferred embodiment;
Fig. 5 be the utility model preferred embodiment another in the middle part of connect the schematic top plan view of arrangement;
Fig. 6 is the schematic top plan view arranging fluting at diaphragm element edge of the utility model preferred embodiment;
Fig. 7 is schematic top plan view diaphragm element shape being arranged to rectangle of the utility model preferred embodiment;
Fig. 8 is traditional silicon microphone warpage and the responsive deformation cross-sectional schematic of vibrating diaphragm of prior art;
Fig. 9 is silicon microphone warpage and the responsive deformation cross-sectional schematic of vibrating diaphragm of the utility model preferred embodiment.
Embodiment
The utility model provides the silicon capacitor microphone of application flexibility backplane, can improve the vibrating diaphragm vibration shape under existing technological level, thus optimizes the indexs such as sensitivity, the linearity, signal to noise ratio, pick-up voltage, sensitization capacitance, dynamic response.Below in conjunction with concrete drawings and Examples, the utility model is described in further detail.
Referring to Fig. 1, is the cross-sectional schematic of the responsive deformation of microphone conductive polycrystalline silicon diaphragm structure in prior art and backplane.In prior art, the sensitivity for the polysilicon vibrating diaphragm 203 ' making silicon capacitor microphone is higher to reach application requirement, how to obtain thinner by its one-tenth-value thickness 1/10, generally the scope of 0.1 ~ 2 micron.Like this, the rigidity of vibrating diaphragm is lower, and sensitivity is higher.As shown in Figure 1, combined by edge conjunction 2042 ' between flexible backplane 205 ' and vibrating diaphragm 203 '.When being subject to acoustic pressure wave and exciting, flexible backplane 205 ' is recessed to dotted line position 2052 ' by horizontal level 2051 ', vibrating diaphragm 203 ' by horizontal level 2031 ' epirelief to dotted line position 2032 '.Common backplane 205 ' and the distortion of vibrating diaphragm 203 ' make the relative change of electric capacity mainly occur in the middle position of vibrating diaphragm 203 ', and the displacement of marginal position is less.Like this, although can find that both relative deformations occupy the clearance space of fixed area between the two and former sacrifice layer (not shown), because primary deformable occurs over just middle position, the efficiency of capacitance variations is restricted.This be due to vibrating diaphragm 203 ' thinner after, the design of the rigidity opposite edges of middle section film and the support section gap declined not obvious.Forces associated theory is pointed out, with rigidity on a slice vibrating diaphragm along with the graded of radius is less, the strain that also can make to occur responsive motion along with the rate of change fluctuation of radius little; In other words, now Displacements Distribution is slowly increased to center by edge.
Under such mechanical model, according to Saint Venant's principle, if it is mild all comparatively greatly to allow displacement be distributed in center, and be suddenly reduced to mooring anchor zone position in edge, thus obtain higher sensitivity, signal to noise ratio and linearity index, just need to take the means such as the thickness as increased center with its central area of hardening to reach respective objects.But affect by factors such as integral rigidity, stress distribution and technological feasibilities, the technique increased by vibrating diaphragm thickness is by high for large for difficulty cost, sensitivity of microphone also reduces, and wishes that the original intention producing premium quality product with low cost process in enormous quantities runs in the opposite direction with the utility model.
In order to solve the problem, please continue to refer to Fig. 2, it is the cross-sectional schematic of the responsive deformation of microphone conductive polycrystalline silicon diaphragm structure of the present utility model and backplane.
In the utility model, backplane 205 is flexible, namely its natural form 2051 does not overlap with stressed change shape 2052, also can connect by rationally arranging middle part the vibration shape 2032 that 2041 adjust vibrating diaphragm 203, make the vibrating diaphragm vibration shape better, thus make the difference of backplane change shape 2052 and the vibrating diaphragm vibration shape 2032 by middle part be connected 2041 optimize after the index such as sensitivity, the linearity, signal to noise ratio, pick-up voltage, sensitization capacitance, dynamic response be all improved.
Forces associated theory is pointed out, the less vibrating diaphragm of polylith divided can be considered on mechanical model at the diaphragm structure being provided with middle part connection 2041 by certain scheme, thus by designing the Stiffness Distribution of the little vibrating diaphragm of every block, reach the effect of the moderate finite deformation efficiency of Fig. 2.Because although the overall natural frequency of vibration of flexible backplane is lower, but the rigidity of its regional area is much larger than diaphragm element, this middle part connect 2041 be arranged so that vibrating diaphragm 203 and backplane 205 are except common displacement (comprising by the deformation under the static external force such as electrostatic force and the warpage affecting rear film by residual stress) except, the difference that both of greater efficiency are out of shape retrains the adjustment of corresponding Stiffness Distribution by this and obtains.Wherein according to Saint Venant's principle, the constraint that middle part connects 2041 is arranged so that the impact of vibrating diaphragm thickness on Stiffness Distribution weakens, and sub-vibrating diaphragm after respectively dividing at the mechanical behavior of regional area closer to its situation as the vibrating diaphragm of reduced size.
Just for this reason, technique and design limitation determine that the thickness of vibrating diaphragm needs to arrange as far as possible thin.And thickeied just for opposing warpage and the object increasing diaphragm area, also need the cost paying technology difficulty and cost simultaneously.The utility model is connected 2041 by arranging movable middle part on the backplane of vibrating diaphragm with flexibility, reaches the object optimizing flexible backplane microphone property.Thus after avoiding using the complicated technology of existing various scheme, using existing low cost process to process more high performance product in enormous quantities becomes possibility.
In Fig. 2, the thickness of vibrating diaphragm 203 is 0.1 ~ 2 micron, because if vibrating diaphragm thickness is too thin, then residual stress distribution is uneven, and diaphragm deformation situation is also uncontrollable; If vibrating diaphragm thickness is too thick, then sensitivity is lower, and be difficult to reach application request, the utility model is lost application value.2041 and edge conjunction 2042 is connected with the mode of selective removal sacrifice layer 204 middle part constructed between vibrating diaphragm 203 with backplane 205, not simple division stress and the distortion of its object, also require that the sensitivity after Stress Release of each diaphragm element more reaches unanimity, and be easy to electrode extraction.Middle part connects 2041 and vibrating diaphragm and backplane is divided into multiple unit area, can be separated between each region by method of geometry, also can be separated by technologic reverse dense doping method, also can not separate.
The material of described vibrating diaphragm 203 can be the conductive polycrystalline silicon realized by the technique of deposit; The material of described flexible backplane 205 also can be the conductive polycrystalline silicon realized by the technique of deposit; Middle part between the moving part and the moving part of described backplane 205 of described vibrating diaphragm 203 is connected 2041, need ensure only have mechanical connection between the two, without electrical communication.This several way can obtain facility when circuit lead.
Be provided with between described vibrating diaphragm 203 moving part and the moving part of described backplane 205 one or more be connected both structure in the middle part of connect 2041, by being combined with preparation technology, according to performance need realization as the weak constraint of freely-supported or similar clamped strong constraint.It is relevant in conjunction with tightness degree that the intensity and the middle part that realize constraint connect the cell size of 2041, residual stress and connection, so also can increase flexibility when adjusting the vibration shape.
Be provided with between described vibrating diaphragm 203 moving part and the moving part of described backplane one or more be connected both structure in the middle part of connect 2041, by remove selectively sacrifice layer technique realize.What can make middle part connection 2041 structures like this realizes technique and existing process compatible, and only needing to adjust relevant sacrifice layer removal figure can realize.Like this, the vibration shape of conductive polycrystalline silicon vibrating diaphragm 203 can be adjusted on original low cost process basis, control its tension force, compliance and deformation, the vibrated film thickness impact of deformation of the large area polysilicon vibrating diaphragm 203 that simple process is realized reduces, not only dynamic response and high order mode suppress better, more have higher sensitivity, signal to noise ratio and the linearity, thus reach at lower cost with the object of high finished product rate production high-performance microphone.
Fig. 3 ~ Fig. 5 is the specific embodiment of restriction relation between vibrating diaphragm 203 and backplane 205 in silicon capacitor microphone of the present utility model respectively.As can be seen from Figure, middle part connect 2041 with edge conjunction 2042 diaphragm element between any two area can optimize needs according to the relative vibration shape between vibrating diaphragm 203 and backplane 205 under differing the basic principle being no more than 50%, have multiple avatar, and constraint intensity and middle part connect 2041 cell size, residual stress and connection relevant in conjunction with tightness degree.For reducing substrate stress to the uncontrollable impact of vibrating diaphragm, its edge conjunction 2042 also can remove.
Fig. 6 with Fig. 7 respectively show by middle part be connected 2041 and fluting 2033 vibrating diaphragm 2031 is divided into the situation of multiple unit, the backplane 2051 relative on vertical paper direction with vibrating diaphragm 2031 does not draw.As shown in Figure 6 and Figure 7, by arranging fluting, in the middle part of being placed through by diaphragm element, connection 2041 is suspended on " plate-beam composite structure " on backplane 2051.It should be noted that if do not needing geometrically to arrange fluting 2033, can mode in its corresponding position by counter-doping, thus the unit of vibrating diaphragm is being connected geometrically, but mutually isolated in electricity.In addition, be connected in the middle part of the part in Fig. 6 with Fig. 7 2041 also can depending on arranging time space layout and electrical traces need to be newly defined as edge conjunction 2042.
In figure 6, do not possess in planar continuous print feature by the diaphragm element shape that vibrating diaphragm is divided into of slotting, but the division requirement of all whole unit shapes of vibrating diaphragm can be adapted to, such splitting scheme, be applicable to the situation that the vibrating diaphragm gross area is less, the gross area space of vibrating diaphragm can be utilized as far as possible.But such scheme, because the size and dimension of each vibrating diaphragm is incomplete same, when affecting by fabrication error, the degree that each vibrating diaphragm is subject to fabrication error interference is not identical yet, like this, the design that is identical or that sequentially distribute of the parameter between each diaphragm element after completing will be subject to larger interference.
In the figure 7, by diaphragm element being divided into the method for rectangle, make the shape of the size of each vibrating diaphragm identical, like this when affecting by fabrication error, the degree that each vibrating diaphragm is subject to fabrication error interference is also close.If wish that the parameter between each diaphragm element after completing is identical, identical fluting can be set for each diaphragm element, if wish that the parameter between each diaphragm element after completing sequentially distributes, also slightly distinguishing method can be realized by the position arranging fluting.Each diaphragm element of such setting, after affecting by close fabrication error, can be compared by different fabrication errors, more easily maintain its relativeness.
Fig. 8 is traditional silicon microphone warpage and the responsive deformation cross-sectional schematic of vibrating diaphragm of prior art; Fig. 9 is silicon microphone warpage and the responsive deformation cross-sectional schematic of vibrating diaphragm of the utility model preferred embodiment.As shown in Figure 8, due to the existence of warpage, the vibrating diaphragm 2031 after warpage no longer keeps being parallel to each other with backplane 2052, and warping of membrane softer in both is larger.Because electric capacity and capacitance variation are all relevant with capacitance gap, after being subject to acoustic signal excitation in the case, the deformation 2032 of vibrating diaphragm makes the signal of whole microphone system and the situation of design differ greatly.This kind of situation can only by impact backplane rigidity strengthened and Controlling Technology parameter suppresses warpage as far as possible in traditional silicon microphone.Along with the increase of chip area, also more and more higher to the requirement of technique.For example, for the vibrating diaphragm of a block feature size 900um, even if upturned 4um is also no more than 5%, but perhaps the lower surface of the upper surface of this vibrating diaphragm distance backplane only has the distance of 5um, because need capacitance gap (air gap) to reduce to ensure enough sensitization capacitance capacitances, but the warpage of 4um account for 80% gap of this capacitor model in some areas, be enough to completely desirable microphone circuit working model was lost efficacy.As shown in Figure 9, if the vibrating diaphragm of this block feature size 900um is divided into three diaphragm element on the direction be concerned about, so under same thickness, each diaphragm element itself discuss direction on rigidity will rise between 27 times, corresponding warpage has also just been ignored.On the other hand, backplane can be made flexible with the residual stress in release process, strengthen fracture toughness.The backplane of such flexibility may make the degree of warpage increase, but as shown in Figure 9, the error of the capacitor model that each diaphragm element is corresponding is less, and when being subject to acoustic signal, the situation 2032 of diaphragm deformation will by normal microphone circuit working model to follow-up link transmission of signal.On the other hand, can by the backplane 2052 after distortion be approximately arc, and the model that diaphragm element is approximately straightway is to estimate that warping phenomenon reduces situation to gas leakage air gap.On the direction of such as Fig. 9, assuming that upwarp 2,4,8,16,32um respectively than edge in the middle part of backplane, then calculated distance reduced 4.2nm, 17nm, 68nm, 0.27um and the 1.1um respectively of the nearest end points of known adjacent segments by geometry.Be loosened to assigned direction 16um as upwarped degree from any direction 2um, process costs has and obviously to decline and more controlled.Obviously under general technology, if the fluting between the unit arranging 1um, when there is the upwarping of above degree, 0.42% can be reduced respectively, 1.7%, 6.8%, 27%, with more than 100% (namely fluting is completely filled, and between diaphragm element, mutually directly contact also influences each other on mechanics, and obviously this is another situation needing to be avoided).As can be seen here, when upwarping degree and being larger, this improves effect is rather considerable.Like this by relaxing the requirement to warping of membrane degree, warpage being guided into same direction and reasonable way of specifying its amount of warpage, technology difficulty and cost can be reduced, and the low cut after slotting is effectively suppressed in flexible backplane scheme.
The utility model also allows the combine with technique adjusting vibrating diaphragm shape and parameter with other, to obtain better effect of optimization.
In addition, the term " top " in specification and claims, " end ", " on ", D score, " left side ", " right side " etc. (if existence) is for illustration of property object and not necessarily for describing permanent relative position.Be understandable that the term so used can exchange in the appropriate case, make embodiment of the present utility model as herein described can at the enterprising line operate in other directions being such as different from above-mentioned or described direction herein.
Illustrative to description of the present utility model above; and it is nonrestrictive; those skilled in the art is understood, and can carry out many amendments, change or equivalence, but they all will fall in protection range of the present utility model within the spirit and scope of claim restriction to it.
Claims (8)
1. a silicon capacitor microphone, comprises substrate, vibrating diaphragm and backplane; Described substrate is provided with an operatic tunes; Described vibrating diaphragm is located at described operatic tunes top, produces mechanical oscillation when being excited by acoustic pressure wave; Described backplane is positioned at described vibrating diaphragm top, between described backplane and described vibrating diaphragm, be provided with fixing air gap, and described vibrating diaphragm, described backplane and described air gap form capacitor jointly; It is characterized in that, the middle part also comprising the one or more insulation be fixedly connected between described vibrating diaphragm and described backplane connects, and the middle part of described one or more insulation connects and described vibrating diaphragm is divided into multiple diaphragm element; Described backplane is flexible.
2. silicon capacitor microphone according to claim 1, is characterized in that, the material of described vibrating diaphragm is doped polycrystalline silicon.
3. silicon capacitor microphone according to claim 1, is characterized in that, needs to carry out serial or parallel connection between each diaphragm element according to electrical lead wire, to form different capacitances.
4. silicon capacitor microphone according to claim 1, is characterized in that, the difference of the area between each diaphragm element is no more than 50%.
5. silicon capacitor microphone according to claim 1, is characterized in that, the edge of described diaphragm element arranges fluting, to form the electric insulation between each diaphragm element and the isolation on space structure.
6. silicon capacitor microphone according to claim 1, is characterized in that, the border of described diaphragm element is arranged reverse dense doping, makes the mode of being isolated by PN junction between each diaphragm element keep electric insulation and maintains the connection on space structure.
7. silicon capacitor microphone according to claim 1, is characterized in that, substrate is only arranged to the fixing anchor district of backplane, and there is not mechanical connection between described vibrating diaphragm and described substrate.
8. silicon capacitor microphone according to claim 1, is characterized in that, the shape of described diaphragm element is any one in triangle, quadrangle or regular hexagon.
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| CN104853300A (en) * | 2015-05-13 | 2015-08-19 | 北京卓锐微技术有限公司 | Silicon capacitance microphone with application of flexible back electrode |
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| CN106303867A (en) * | 2015-05-13 | 2017-01-04 | 无锡华润上华半导体有限公司 | Mems microphone |
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