Specific embodiment
In order to which the technical problems to be solved in the utility model, technical solution and beneficial effect is more clearly understood, below
In conjunction with the embodiments, the present invention will be further described in detail.It should be appreciated that specific embodiment described herein is only
To explain the utility model, it is not used to limit the utility model.
In the utility model embodiment, hereafter noun is made as described below.
Term used in the utility model " resonator ", English Resonators refer to the electronics member for generating resonance frequency
Part.
Thin film bulk acoustic wave resonator: Film Bulk Acoustic Resonator (FBAR), be using silicon base plate, by
MEMS technology and thin film technique and manufacture.Image cancellation, parasitic filtering and channel choosing are realized in wireless transceiver
The features such as functions such as selecting, having higher q values and easily realize micromation.
On the one hand, the utility model embodiment provides a kind of thin film bulk acoustic wave resonator.The thin film bulk acoustic wave resonator
Structure it is as shown in Figure 1 comprising substrate 1, supporting layer 2, the first bottom electrode layer 3, temperature drift layer 4 and sandwich piezoelectricity pile structure 5,
And by the substrate 1 to the direction of the sandwich piezoelectricity pile structure 5, the substrate 1, supporting layer 2, the first bottom electrode layer 3, temperature
It floats layer 4 and sandwich piezoelectricity pile structure 5 stacks gradually combination.
Wherein, the substrate 1 at least has a surface 11, and the oriented lining is opened up on the middle part on a surface 11
1 internal direction of bottom is recessed the groove 12 to be formed;The area of the groove 12 it is natural be that supported layer 2 covers
, in order to which the groove 12 encloses cavity 13 with the supporting layer 2.
In one embodiment, the deep-controlled of the groove 12 is being not more than, and preferably slightly smaller than 3 μm.Wherein, the groove
12 depth is the slot bottom of the groove 12 to the vertical range of notch.Deep-controlled by groove 12 is not more than 3 μm of preferred controls
System is slightly less than 3 μm, on the one hand can effectively control the etching of groove 12, it is often more important that control the size of the groove 12, such as
Quality factor Q value can be improved in depth, reduces the interference of spurious clutter, reduces insertion loss, effectively improves the thin-film body sound
The bandwidth of wave filter.In addition, the material of the substrate 1 is usually to select elemental silicon.
The supporting layer 2 is that stacking is incorporated on the surface 11 for offering the groove 12 of the substrate 1, this
Sample, the supporting layer 2 enclose the closed cavity 13 with groove 12.In one embodiment, the supporting layer 2 is Si3N4Film
Layer, amorphous state AlN film layer, Si3N4With any one layer in amorphous state AlN mixture film.Wherein Si3N4Film layer and AlN film layer
All have excellent stability, but the Si3N4In contrast film layer has stress is small to be such as close to 0, therefore, the branch
Supportting layer 2 is preferably Si3N4Film layer.In further embodiment, the supporting layer 2 with a thickness of 1000-1200 Ethylmercurichlorendimide.By to institute
The control of the factors such as material and the thickness of supporting layer 2 is stated, the internal stress of the supporting layer 2 on the one hand can be effectively improved, such as answer
Power is substantially zeroed, and compact structure, guarantees the stability of supporting layer structure, effectively plays the supporting role of supporting layer 2;It is another
Aspect assigns the supporting layer 2 stable chemical property, guarantees in the thin film bulk acoustic wave resonator in use and preparation process
In chemistry and structure stability, to guarantee the stabilization of the thin film bulk acoustic wave resonator performance.
First bottom electrode layer 3 be stacking be incorporated in the supporting layer 2 on the surface of the substrate 1.One
In embodiment, the material of first bottom electrode layer 3 is at least one of Mo, Al, Pt, W, Au, Al, Ni, Ag, that is to say Mo
Film layer, Al film layer, Pt film layer, W film layer, Au film layer, Al film layer, Ni film layer, any one layer in Ag film layer, or containing Mo, Al,
The compound film layer of at least two materials in Pt, W, Au, Al, Ni, Ag, preferably Mo film layer.In another embodiment, described
First bottom electrode layer 3 with a thickness of 2300-2500 Ethylmercurichlorendimide.It is special by the material and thickness control to first bottom electrode layer 3
It is not to set Mo film layer for the first bottom electrode layer 3, can effectively increases acoustic impedance, improves the reflection of the sound wave in Air Interface
Ability can preferably reduce the interference of reflection clutter, improve the Q value of product.
The temperature drift layer 4 be stacking be incorporated in first hearth electrode 3 on the surface of the supporting layer 2.It is described
Setting up for temperature drift layer 4 can effectively improve frequency-temperature coefficient, improve electromechanical coupling coefficient, improve stability.Therefore, implement one
In example, the temperature drift layer is the mixing of fluorine-doped silica (SiOF) film layer, silica coating, fluorine-doped silica and silica
Any one layer in object film layer, preferably fluorine-doped silica (SiOF) film layer.In another embodiment, the thickness of the temperature drift layer
Preferably 800 Ethylmercurichlorendimides.The film layer and thickness of the material assign the temperature drift layer 4 and improve frequency-temperature coefficient, reduce temperature drift, improve
Electromechanical coupling coefficient improves stability, while it can also improve and act synergistically between the temperature drift layer 4 and other layer of structure, thus
Optimize loss, the temperature coefficient, temperature drift, power endurance, working frequency, electromechanical coupling of the thin-film bulk acoustic wave filter
The performances such as number, compatibility.In a preferred embodiment, the foreign atom of fluorine (F) is hundreds of in fluorine-doped silica (SiOF) film layer
Score is 8-9%, can effectively improve the performance of the temperature drift layer 4, to improve the quality factor of thin film bulk acoustic wave resonator
(Q) it is improved with electromechanical coupling factor.
The sandwich piezoelectricity pile structure 5 is the surface away from first bottom electrode layer 3 for being layered in the temperature drift layer 4
On.The structure of the sandwich piezoelectricity pile structure is as shown in Figure 1, it is by top electrode layer 51, piezoelectric layer 52 and the second hearth electrode
Layer 53 stacks gradually to be formed, and second bottom electrode layer 53 is combined with the temperature drift layer 4 stacking.
Wherein, in one embodiment, the top electrode layer 51 is at least one of Mo, Al, Pt, W, Au, Al, Ni, Ag,
It that is to say Mo film layer, Al film layer, Pt film layer, W film layer, Au film layer, Al film layer, Ni film layer, any one layer in Ag film layer, or contain
There are the compound film layer of at least two materials in Mo, Al, Pt, W, Au, Al, Ni, Ag, preferably Mo film layer;Its thickness can
To ask as 2300-2500 Ethylmercurichlorendimide.By the way that the material and thickness control of top electrode layer 51, such as the material of top electrode layer 51 are preferably controlled
It is made as Mo, enables to the acoustic impedance of the sandwich piezoelectricity pile structure 5 higher in this way, albedo is stronger, effectively reduces and posts
Raw noise jamming, further enhances signal.
The piezoelectric layer 52 is in aluminium nitride (AlN) film layer, zinc oxide film, aluminium nitride and zinc oxide mix film layer
Any one layer;Preferred aluminium nitride (AlN) film layer is aluminium nitride (AlN) film layer of Mg and Hf doping.The piezoelectric layer 52
Thickness can be conventional thickness, for example but not just for 11000 Ethylmercurichlorendimides.Pass through the material and thickness to the piezoelectric layer 52
The piezoelectric layer 52, is especially set as aluminium nitride (AlN) film layer of Mg and Hf doping by control optimization, so that piezoelectric constant increases
Big and elastic constant reduces, to improve the piezoelectric property and electromechanical coupling factor of the piezoelectric layer 52, effectively improves film
The bandwidth of bulk acoustic wave resonator.
Second bottom electrode layer 53 is at least one of Mo, Al, Pt, W, Au, Al, Ni, Ag, that is to say Mo film layer,
Al film layer, Pt film layer, W film layer, Au film layer, Al film layer, Ni film layer, any one layer in Ag film layer, or containing Mo, Al, Pt, W,
The compound film layer of at least two materials in Au, Al, Ni, Ag, preferably Mo film layer;Its thickness can ask as 2300-
2500 Ethylmercurichlorendimides.By by the material and thickness control of the second bottom electrode layer 53, making it play association together with the top electrode layer 51
Same-action, so that the acoustic impedance of the sandwich piezoelectricity pile structure 5 is higher, albedo is stronger, and it is dry to effectively reduce spurious clutter
It disturbs, further enhances signal.
Based on the various embodiments described above, as the utility model specific embodiment, the support of the thin film bulk acoustic wave resonator
Layer 2 is Si3N4Film layer, with a thickness of 1000-1200 Ethylmercurichlorendimide;First bottom electrode layer 3 is Mo film layer, with a thickness of 2300-
2500 Ethylmercurichlorendimides;The temperature drift layer is fluorine-doped silica (SiOF) film layer, with a thickness of 2500 Ethylmercurichlorendimides;The top electrode layer 51 is Mo
Film layer, with a thickness of 2300-2500 Ethylmercurichlorendimide;The piezoelectric layer 52 is aluminium nitride (AlN) film layer, with a thickness of 11000 Ethylmercurichlorendimides;Institute
Stating the second bottom electrode layer 53 is Mo film layer, with a thickness of 2300-2500 Ethylmercurichlorendimide.By by each of the thin film bulk acoustic wave resonator
Layer material and thickness concurrently set and control, and the effect that can play each layer simultaneously, significantly improves the synergistic effect between each layer,
To significantly improve loss, the temperature coefficient, temperature drift, power endurance, working frequency, electromechanics of the thin film bulk acoustic wave resonator
The performances such as the coefficient of coup, compatibility, Q value.First bottom electrode layer 3, second bottom electrode layer 53 and top electricity as will be described
Pole layer 51 concurrently sets as Mo film layer, and controls each electrode layers thickness, so that each electrode layer is made playing each electrode layer itself
On the basis of, at the same three play synergistic effect, play and further increase acoustic impedance, improve in Air Interface sound wave it is anti-
Ability is penetrated, the interference of reflection clutter can be preferably reduced, improve the Q value of the thin film bulk acoustic wave resonator.
Therefore, the thin film bulk acoustic wave resonator is due to being additionally arranged the temperature drift layer 4, on this basis, preferably to it
The factors such as the material and thickness of contained top electrode layer 51, the second bottom electrode layer 53 and the first bottom electrode layer 3 and supporting layer 2
Optimization and control assign the thin film bulk acoustic wave resonator and low, temperature coefficient are lost so that playing synergistic effect between each layer
It is small, temperature drift is low, power endurance is high, working frequency is high, electromechanical coupling factor is high, good compatibility, assign the film bulk acoustic
Resonator has good Q value, and stable working performance.
In addition, thin film bulk acoustic wave resonator described above can be prepared as follows.It is described thin in conjunction with Fig. 1 and Fig. 3
The preparation method process flow of membrane body acoustic resonator is as shown in Fig. 2, it includes the following steps:
S01: carrying out etching processing on a surface 11 of substrate 1, forms groove 12, as shown in Figure 3A;
S02: sacrificial layer 14 is formed in the groove 12, as shown in figs. 3 b and 3 c;
S03: supporting layer 2, and the branch are formed on the surface of the sacrificial layer 14 and the surface 11 of the substrate 1
Support layer 2 covers the sacrificial layer 14 and at least covers the surface 11 of the substrate 1 around the sacrificial layer 14;Such as Fig. 3 D
It is shown;
S04: along the substrate 1 to the extension method of supporting layer 2, first is sequentially formed on the surface of the supporting layer 2
Bottom electrode layer 3, temperature drift layer 4, the second bottom electrode layer 53, piezoelectric layer 52 and top electrode layer 51;As shown in Figure 3D;
S05: it discharges the sacrificial layer 14 and handles, form closed cavity 13;As shown in FIGURE 3 E.
Specifically, in above-mentioned steps S01, substrate 1 can select the lining of the substrate conventional material of thin film bulk acoustic wave resonator
Elemental silicon such as can be used in bottom.The substrate 1 should at least have a surface, such as at least have a surface 11.
The method that groove 12 is formed on the surface 11 of the substrate 1 can use dry etching or wet etching work
Skill realizes the groove 12 that formation is etched on the surface 11 of the substrate 1.For example make sacrificial layer 14 more smooth,
The utility model embodiment reinforces deep etching (DRIE) technology using plasma in dry etching and etches to form groove 12.This is
Because there are three significant advantages for dry etching relative to wet etching: first, dry etching controllability is good, it may be convenient to
It starts and stops;Fainter temperature change will not influence too much etching on substrate, this two o'clock makes it compare wet etching
There is better repeatability.Second, dry etching is because there is very high anisotropy, in the lesser device fabrication stream of characteristic line breadth
Cheng Zhong, applicability are stronger.When using wet etching, 45 ° of steps that isotropic etching generates may be because that self-stopping technology effect makes
The etching depth of graph window does not reach requirement, and etching speed when discharging to the later period is greatly affected.Third compares liquid
Body solvent, plasma environment granule number magnitude substantially reduce, to negatively affecting more caused by subsequent multi-layer silicon face technique
It is small.
After etching processing in step S01 forms groove 12, exposes and will form natural oxidizing layer in air, and oxide layer
Etching speed it is slower.Therefore, in an embodiment, the depth that etching processing forms groove 12 in step S01 is slightly less than 3 μm.Separately
Outside, the area of the groove 12 is preferably but not just for 1123 μm of 1123 μ m.The groove 12 of the size can not only play by
Supporting layer 2 and groove 12 enclose the effect of the closed cavity 13, but also can effectively improve in the flat of sacrificial layer 14
Whole degree.
The material and flatness of sacrificial layer 14 in above-mentioned steps S02 all to the preparation of the thin film bulk acoustic wave resonator and
The phenomenon that performance all has a great impact, and the sacrificial layer 14 of male-type is easy to happen cracking at step in the subsequent process,
Therefore, it should flatening process be implemented to sacrificial layer, to reduce the appearance of step to the greatest extent.
Therefore, in one embodiment, the technique of the sacrificial layer 14 is formed in addition to effectively controlling as carved in above-mentioned steps S01
It loses processing to be formed except the technology controlling and process and size Control of groove 12, should also be controlled with the following method, to improve
Form the quality and flatness of sacrificial layer 14:
Control the forming method of the sacrificial layer 14: in view of the thin film bulk acoustic wave resonator has multi-layer film structure,
14 upper layer film of sacrificial layer that is to say the solvent effect during supporting layer 2 may be discharged, and the material of sacrificial layer 14 should have
Have that rate of release is fast, the release solvent not characteristic with sacrificial layer upper layer film reaction, therefore, and in an embodiment, the sacrificial layer 14
Material selection phosphorus doping amorphous SiO2.Preferably, in the amorphous SiO of phosphorus doping2The foreign atom number percentage composition of middle phosphorus can
To control as 5-10%.
In another embodiment, the amorphous SiO2The amorphous SiO of preferred phosphorus doping2It can be using PECVD growth
SiO2It is to form the sacrificial layer 14.In this way in the release process of later steps S05, amorphous SiO is removed2Solution not
It does not react with such as supporting layer 2 on upper layer;And the amorphous SiO of PECVD growth2The amorphous SiO of preferred phosphorus doping2Compared with
To be loose, the etching speed in HF is 1 μm/min, considerably beyond the SiO of thermal oxide growth2The etching speed of 80nm/min
Degree.In addition, PECVD system utilizes ion bombardment surface from the perspective of process choice, energy is provided to secondary substance, is made
It obtains them and further prolongs diffusion into the surface in the case where there is high underlayer temperature, have good effect filling small geometrical aspects
Fruit is met well due to the smaller required requirement of device feature line width.
In a particular embodiment, amorphous SiO is grown using PECVD2The method of the layer sacrificial layer 14 is as follows:
With SiO2It is target with P, using CVD method in the groove 12 and the surface of the substrate 1
The amorphous SiO of 11 deposition P doping2Layer.
Wherein, this mix P silica production use medium plasma enhanced CVD method, abbreviation PECVD,
Under the vacuum pressures, the rf electric field being added on electrode plate makes reaction chamber gas that glow discharge occur, and produces in glow discharge region
Raw a large amount of electronics.These electronics obtain sufficient energy under the action of electric field, itself temperature is very high, it and SiO2And P
Doping target collides, and activates gas molecule.They are adsorbed on substrate, and concurrent biochemical reaction generates deielectric-coating, specifically
It is the amorphous SiO of P doping2Film layer, by-product are desorbed from substrate, are taken away with primary air by vacuum pump.
In addition, the amorphous SiO formed2Layer structure is as shown in Figure 3B, so that the amorphous SiO of growth2Thickness degree is more than
The depth of the groove 12, and the amorphous SiO that the surface 11 of substrate 1 is grown2Layer is completely covered.
Due to the amorphous SiO of growth2Thickness degree has been more than the depth of the groove 12, and therefore, it is necessary to the amorphous to generation
SiO2Layer is ground, and removes the amorphous SiO being grown on the surface 112.Chemical mechanical grinding can specifically be used
(CMP) it handles, that is to say using chemical tendering and physical mechanical grinding, to form a completely flat, free of contamination surface
Technology.By the amorphous SiO on silicon face 112Layer is all got rid of, and realizes the planarization of sacrificial layer 14.In specific experiment process
Middle discovery, the gob speed of lapping liquid and the revolving speed of abrasive disk are the important parameters that can be had an impact to polishing in CMP.Through studying
Compare 100rpm and 60rpm discovery: in the case where being polished using 100rpm, pad interface is more dry, hard polishing
Pad plays main polishing action to substrate surface, because of the raising of revolving speed, removal rate has apparent increasing, can obtain relatively good
Grinding rate.And in the case where using 60rpm polishing, abrasive material is more sufficient under same gob speed, and abrasive material is to substrate surface
Main polishing action is played, flatness in the case of 100rpm compared with increasing, but speed reduces.Therefore, smooth in order to obtain
Sacrificial layer 14, the preferred 100rpm of the utility model embodiment is by the amorphous SiO on silicon face 112Layer is all got rid of, and is realized sacrificial
The planarization of domestic animal layer 14.Ideally, as the amorphous SiO on surface 112After layer completely removes, stop etching immediately, or pass through
Self-stopping technology method can be obtained smooth sacrificial layer 14, but since experiment condition limits, it is understood that there may be overlong time is to substrate
Grinding phenomenon is crossed, in this case, because of SiO2Hardness be slightly larger than silicon, such SiO2It is smaller to cross degree of grinding, sacrificial layer 14
Surface 11 can be slightly above.After experiment is completed and measured, discovery sacrificial layer 14 and 11 height error of surface are within 100nm.Tool
The amorphous SiO to generation of body2Layer, which is ground, obtains smooth sacrificial layer 14 as shown in Figure 3 C.
In above-mentioned steps S03, the material for forming the supporting layer 2 can be Si3N4, in any one in amorphous state AlN,
It is preferably Si3N4.Therefore, the supporting layer 2 is Si3N4Film layer, amorphous state AlN film layer, Si3N4With amorphous state AlN mixture
Any one layer in film layer, preferably Si3N4Film layer.In further embodiment, by controlling the method for forming the supporting layer 2
The thickness control of the supporting layer 2 of formation can be 1000-1200 Ethylmercurichlorendimide by condition.In a particular embodiment, described in formation
The method of supporting layer 2 can carry out forming supporting layer 2 using LPCVD method, preferably form Si using LPCVD3N4Layer, so that
The supporting layer 2 such as Si of formation3N4Layer is finer and close, and stability is more preferable, and stress is substantially zeroed.
In above-mentioned steps S04, the first bottom electrode layer 3 for being formed on 2 surface of supporting layer, in 4 table of temperature drift layer
The material of the second bottom electrode layer 53 and the top electrode layer 51 formed on 52 surface of piezoelectric layer that are formed on face can be identical
Or any one different at least one of Mo, Al, Pt, W, Au, Al, Ni, Ag, preferably Mo.By controlling shape
It, can respectively will be described in formation at the method condition of first bottom electrode layer 3, the second bottom electrode layer 53 and top electrode layer 51
The thickness control thin film bulk acoustic wave resonator for example above of first bottom electrode layer 3, the second bottom electrode layer 53 and each layer of top electrode layer 51
Described in the first bottom electrode layer 3, the second bottom electrode layer 53 and each layer of top electrode layer 51 thickness.
The material for forming the piezoelectric layer 52 can be any one in aluminium nitride (AlN), zinc oxide (ZnO), therefore,
The piezoelectric layer 52 is any one layer in aluminium nitride film layer, zinc oxide film, aluminium nitride and zinc oxide mix film layer, preferably
For aluminium nitride film layer.In one embodiment, the aluminium nitride (AlN) is the aluminium nitride (AlN) of Mg and Hf doping, wherein the Mg
It can be 10-15% with foreign atom number percentage composition of the Hf in aluminium nitride (AlN).The piezoelectric layer 52 is formed by control
Method condition, can by the thickness control of the piezoelectric layer 52 be 11000 Ethylmercurichlorendimides.In a particular embodiment, the pressure is formed
The method of electric layer 52 is as follows:
Respectively using AlN and Mg and Hf as target, using magnetron sputtering method on the surface of second bottom electrode layer 53
The aluminium nitride film layer for depositing Mg and Hf doping, that is to say the piezoelectric layer 52.
In one embodiment, the magnetron sputtering electricity source frequency is 1-30MHz.In addition, the magnetron sputtering method can be
Low pressure is as low as (2 × 10-2Pa it is carried out under).
The material for forming the temperature drift layer 4 can be fluorine-doped silica (SiOF), SiO2At least one of, preferably mix
Fluorine silica (SiOF).Therefore, the temperature drift layer 4 is fluorine-doped silica film layer, silica coating, fluorine-doped silica and dioxy
Any one layer in the mixture film of SiClx, preferably fluorine-doped silica film layer.The temperature drift layer 4 is formed additionally by control
Method condition, can by the thickness control of the temperature drift layer 4 be 800 Ethylmercurichlorendimides.In a particular embodiment, the temperature drift layer is formed
4 method can be using magnetron sputtering method depositional coating.In one embodiment, the magnetron sputtering electricity source frequency is 1-
30MHz.In addition, the magnetron sputtering method can be in low pressure as low as (2 × 10-2Pa it is carried out under).
In above-mentioned steps S05, discharge the sacrificial layer 14 be in order to which the sacrificial layer 14 is exported from groove 12, thus
Form cavity 13.In utility model people it was found that, being released in the more crucial sacrificial layer 14 of MEMS technology in release processing procedure
The adhesion effect generated after the completion of putting is faced greatest difficulty.Adhesion effect is primarily referred to as in the pre-filled material of sacrificial layer 14
After material is completely removed, during ultrapure water (DI) cleans removal residual solution, due between 14 superstructure of sacrificial layer
Liquid flows, and more fragile 14 superstructure of sacrificial layer is pulled to sacrificial layer lower surface by the surface tension of liquid, thus
The phenomenon that causing adherency to be destroyed the cavity to be formed 13.And when sacrificial layer 14 superstructure film layer such as supporting layer 2 with it is sacrificial
After 14 lower surface of domestic animal layer adhere to, Van der Waals for, electrostatic force between upper and lower surface and bonding force will be between upper and lower film layers
It has an effect, 13 structure of the cavity to have collapsed is made to be difficult to restore.In addition, to the rate of the sacrificial layer 14 release lateral etching
The rate far smaller than radially to etch, total release time is longer, and needs to prepare additional metal electrode in standard technology and exist
It can also be eroded by a degree of in release reagent, so, discharge selection of the reagent to sacrificial layer 14 material and metal electrode
Property be also intended to consider a key factor.
In one embodiment, the release reagent for discharging the sacrificial layer 14 includes HF, NH3The components such as F and glycerol.Preferably
Described HF, NH3The mass ratio of F and glycerol is 1:(3.8-4.2): (1.7-2.3), it is specific such as 1:4:2.Utility model people is grinding
It is found in hair, in each layer structure of the thin film bulk acoustic wave resonator, be easiest to react with HF is extension Mo pressure welding electricity
Pole (device accessory structure), if Mo and AlN property is all relatively stable, the speed being etched in HF is very slow, so obtain
Mo and SiO2Optimal selection than can be solved HF release when etching selection problem.Research finds to work as glycerol (C3H8O3) plus
After entering HF, Mo and SiO can be improved2The selection of etching is than (HF is very faint to the corrosivity of Mo, can ignore herein), to realize
14 release process of prolonged sacrificial layer.Therefore, the release reagent of above-mentioned formula passes through the control to effective component and content, energy
The diffusivity for enough effectively increasing release reagent makes release reagent be easier to realize sideways diffusion in the gap of sacrificial layer 14, increases
Add the rate of lateral encroaching.
Further, on the basis of the release agent prescription, by the temperature control for discharging the processing of sacrificial layer 14
System can be controlled effectively and discharge the time that the sacrificial layer 14 is handled.In one embodiment, it is released using the release reagent
Putting the temperature that the sacrificial layer 14 is handled is 50-55 DEG C.Specific utility model people is the study found that at 45 DEG C hereinafter, 40%
The selection of wtHF is than being higher than the mixed liquor after glycerol is added, but absolute figure of etching ratio under low temperature itself far can not expire
The requirement of foot length time sacrificial layer release.After temperature rises to 60 DEG C, the etching selection ratio of the mixed liquor after glycerol is added
621 have been had reached, and the etching selection ratio of pure HF then rises slowly, still only 151, it is not able to satisfy the requirement of release.
In addition, very long due to discharging the time that the sacrificial layer 14 is handled, the release reagent reacts slower with 14 material of sacrificial layer,
The release reagent on 14 surface of sacrificial layer can decrease lower than the concentration on solution surface layer by reaction density, therefore, excellent
Choosing carries out being slowly stirred processing in discharging 14 treatment process of sacrificial layer to the release reagent, to guarantee the sacrifice
The rate of release of layer 14 is maintained at certain numerical value.
Utility model people is under study for action it has furthermore been found that the release window shape of the sacrificial layer 14 and release window position
Influence whether to discharge the sticking problem of 14 treatment process of sacrificial layer.Specifically find existing sacrificial layer in diffraction fringe region
Obviously there is the case where adherency, this is because existing release window area is excessive, the pre-filled material of sacrificial layer and micro- overarm knot
Structure comes into contact in a large area with etching liquid simultaneously, and etching liquid enters inside configuration by the bad region of step coverage, to structural membrane
Layer produces certain corrosion, causes hanging structure more fragile at sideline.In order to overcome existing defect, in an embodiment,
Discharging the release window of the sacrificial layer 14 is as shown in Figure 4 through the supporting layer 2, the first bottom electrode layer 3, temperature drift layer 4
With the through-hole 6 (relief hole) of sandwich piezoelectricity pile structure 5, the through-hole 6 is communicated with the cavity 13, the sacrificial layer described in this way
14 can be discharged from the through-hole 6.Wherein, the quantity of the through-hole 6 can be at least one, such as can with but be not only
2, so as to the release of the release reagent and the sacrificial layer 14.In another embodiment, it that is to say in the release window
On the basis of through-hole 6 (relief hole) position, in an embodiment, the diameter of the release window is preferably 0.1 μm of circular hole.
It further include being started the cleaning processing to the cavity 13 of formation after the release sacrificial layer 14 is disposed
The step of.In one embodiment, cleaning solvent used by the cleaning treatment is acetone (CH3COCH3).In this way due to acetone
Density is smaller, and surface tension is far smaller than water, while having volatile characteristic again, when can shorten the effect of adhesion effect
Between.
Therefore, the preparation method of the thin film bulk acoustic wave resonator by the step of forming supporting layer 2 with formed
The step of adding the step of forming the first bottom electrode layer 3 between the step of second bottom electrode layer 53 and forming temperature drift layer 4, makes
The thin film bulk acoustic wave resonator formed, which must be prepared, has the first bottom electrode layer 3 and temperature drift layer 4, while to the formation film
The control of the method, process conditions and material of each layer of bulk acoustic wave resonator realizes that formation makes to each layer structure optimization and control
It obtains and plays synergistic effect between each layer structure, the thin film bulk acoustic wave resonator for assigning preparation, which has, is lost low, temperature coefficient
Small, the advantages that temperature drift is low, power endurance is high, working frequency is high, electromechanical coupling factor is high, good compatibility, while described in assigning
Thin film bulk acoustic wave resonator has good Q value, and stable working performance.In addition, by discharging at the sacrificial layer 14
The correlative factor of reason, to release reagent, temperature and to release as described in sacrificial layer 14 processing as described in release window position and
The control and optimization of size guarantee that the bad phenomenons such as generation of collapsing and crack do not occur for the cavity 13 to be formed, to guarantee cavity
The planarization of each layer structure on 13 tops.Secondly, the preparation method process conditions are easily-controllable, the thin-film body of preparation ensure that
Acoustic resonator structure and performance are stablized, and preparation cost is reduced.
Another aspect, on the basis of thin film bulk acoustic wave resonator described above and preparation method thereof, the utility model is real
It applies example and additionally provides a kind of thin-film bulk acoustic wave filter.The thin-film bulk acoustic wave filter includes thin-film body sound described above
Wave resonator.Therefore, the thin-film bulk acoustic wave filter is described thin in this way due to containing thin film bulk acoustic wave resonator described above
The loss of membrane body acoustic wave filter is low, temperature coefficient is small, temperature drift is low, power endurance is high, working frequency is high, electromechanical coupling factor
High, good compatibility, and there is good Q value.
Now in conjunction with specific example, the present invention will be further described in detail.Wherein, hereafter in each embodiment
What "/" indicated is the meaning that stacking combines.
The constructive embodiment of 1 thin film bulk acoustic wave resonator