CN110198158A - Bulk acoustic wave resonator and its manufacturing method - Google Patents
Bulk acoustic wave resonator and its manufacturing method Download PDFInfo
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- CN110198158A CN110198158A CN201910276219.7A CN201910276219A CN110198158A CN 110198158 A CN110198158 A CN 110198158A CN 201910276219 A CN201910276219 A CN 201910276219A CN 110198158 A CN110198158 A CN 110198158A
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- 238000005530 etching Methods 0.000 claims abstract description 66
- 238000000034 method Methods 0.000 claims abstract description 30
- 230000009514 concussion Effects 0.000 claims abstract description 19
- 238000004891 communication Methods 0.000 claims abstract description 6
- 229910052751 metal Inorganic materials 0.000 claims description 58
- 239000002184 metal Substances 0.000 claims description 56
- 239000010409 thin film Substances 0.000 claims description 34
- 238000010438 heat treatment Methods 0.000 claims description 23
- 238000001312 dry etching Methods 0.000 claims description 6
- 238000004151 rapid thermal annealing Methods 0.000 claims description 6
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- 239000010931 gold Substances 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 230000003628 erosive effect Effects 0.000 claims 1
- 239000004744 fabric Substances 0.000 claims 1
- 230000017525 heat dissipation Effects 0.000 abstract description 5
- 239000010410 layer Substances 0.000 description 93
- 239000000463 material Substances 0.000 description 18
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 15
- 229910052710 silicon Inorganic materials 0.000 description 15
- 239000010703 silicon Substances 0.000 description 15
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 12
- 230000008569 process Effects 0.000 description 10
- 239000011241 protective layer Substances 0.000 description 9
- 239000007769 metal material Substances 0.000 description 8
- 239000010408 film Substances 0.000 description 7
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 6
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- 239000011733 molybdenum Substances 0.000 description 6
- 229910052763 palladium Inorganic materials 0.000 description 6
- 238000010897 surface acoustic wave method Methods 0.000 description 5
- 239000004411 aluminium Substances 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
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- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
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- 239000000126 substance Substances 0.000 description 2
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- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- HIVGXUNKSAJJDN-UHFFFAOYSA-N [Si].[P] Chemical compound [Si].[P] HIVGXUNKSAJJDN-UHFFFAOYSA-N 0.000 description 1
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- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
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- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02086—Means for compensation or elimination of undesirable effects
- H03H9/02102—Means for compensation or elimination of undesirable effects of temperature influence
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/56—Monolithic crystal filters
- H03H9/564—Monolithic crystal filters implemented with thin-film techniques
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
- Micromachines (AREA)
Abstract
The present invention relates to a kind of bulk acoustic wave resonator and its manufacturing methods, this method comprises: providing substrate；Several spaced holes are formed on the surface of the substrate；It is heat-treated, so that several holes are merged at least one hanging closed cavity；Being formed over the substrate, there is the piezoelectricity of opening to shake stack layers；Isotropic etching is carried out to the substrate for being exposed to the opening, continue to carry out the isotropic etching to the substrate around the closed cavity after being etched to the closed cavity, to form the cavity with the open communication on the surface of the substrate, at least partly described piezoelectricity concussion stack layers are located on the cavity.Technical solution of the present invention can obtain bigger cavity in substrate surface, to be more advantageous to heat dissipation.
Description
Technical field
The present invention relates to microelectromechanical systems (Micro-Electro-Mechanical System, abbreviation MEMS) necks
Domain more particularly to a kind of bulk acoustic wave resonator and its manufacturing method.
Background technique
In recent years, wireless communication has become a part for people's lives.Originally, people are only capable of carrying out voice using mobile phone
Call and the transmitting-receiving of short message.However, smart phone and tablet computer can be supported more and more by third party software now
Function, this just needs them that can carry out the quick transmission of Various types of data under multiband.With 4G maturation and 5G arriving,
The number of frequency bands that mobile phone is supported is rising rapidly.It was predicted that arriving the year two thousand twenty, the number of frequency bands that 5G application is supported will be realized root
Be doubled, increase 50 or more communications bands newly, the total frequency range supported of global 2G/3G/4G/5G network is up to 91 or more, hand
Filter in machine will increase to more than 100, and global filter market annual requirement will be up to 200,000,000,000.
Radiofrequency signal quality depends on the radio-frequency filter in mobile phone, and acoustic resonator is radio-frequency filter and sensor
Basic module.There are mainly three types of existing radio-frequency filters: dielectric filter, surface acoustic wave (SAW) resonator and thin-film body sound
Wave resonator (FBAR).Dielectric filter is the metal layer in the covering of its surface as electric wall, and electromagnetic wave is limited in medium
It is interior, standing wave concussion is formed, major advantage is that power capacity is big, insertion loss is low, but volume is big, difficult integrated.Surface acoustic wave
Resonator is to output and input interdigital electrode in the upper surface of its Piezoelectric Substrates (such as lithium niobate) with the means formation of photoetching,
Surface acoustic wave is motivated using piezoelectric effect, and detects output.SAW resonator size is smaller than dielectric filter, but its
Insertion loss is big, and is restricted by photoetching technique that working frequency is lower, power capacity is low, difficult integrated.Bulk acoustic wave resonator exists
Dielectric filter and surface resonator are surmounted in performance comprehensively, frequency is determined by the thickness of piezoelectric layer, therefore frequency can
To be much higher than surface resonator, and it is small in size, insertion loss is low, Out-of-band rejection is good, power capacity is high, easy of integration.Cause
This, bulk acoustic wave resonator is research hotspot in recent years.
Fig. 1 is a kind of structural schematic diagram of existing silicon reverse side etching type bulk acoustic wave resonator.As shown in Figure 1, the bulk acoustic wave
Resonator 100 includes the silicon substrate 101 with reverse side etch cavity 102, the supporting layer being sequentially stacked on silicon substrate 101
103, lower electrode 104, piezoelectric layer 105 and top electrode 106.Lower electrode 104, piezoelectric layer 105, top electrode 106 constitute sandwich knot
Structure, also referred to as piezoelectricity shake heap.The resonator 100 removes big portion from silicon wafer reverse side etching using MEMS body silicon micro manufacturing technique
Point silicon materials, with piezoelectricity concussion heap lower surface formed air interface, thus by sound wave be limited to piezoelectricity concussion heap it
It is interior, heat dissipation problem can be preferably solved in this way, effectively reduce sound leakage, but its structural stability is poor.
Fig. 2 is the structural schematic diagram of existing another air type bulk acoustic wave resonator.As shown in Fig. 2, the resonator 200
Including with air-gap chamber 202 silicon substrate 201, stack gradually supporting layer 203 on a silicon substrate 201, lower electrode 204, pressure
Electric layer 205 and top electrode 206.Lower electrode 204, piezoelectric layer 205, top electrode 206 constitute sandwich structure, and also referred to as piezoelectricity shakes
Swing heap.The resonator 200 first passes through DRIE technique and etches air-gap chamber 202, then deposits sacrificial layer material (such as phosphorus silicon glass
Glass), chemical mechanical grinding (CMP) then is carried out to sacrificial layer material, is finally discharged again, air-gap chamber 202 is exposed,
The lower surface that piezoelectricity shakes heap forms air interface, so that sound wave is limited within piezoelectricity concussion heap.Such structure can
It effectively prevent sound leakage, stability good, but it is not smooth to radiate, and the technique is related to the growth of sacrificial layer material, CMP and releases
It puts, technology difficulty is high and equipment is expensive.
Therefore, how to obtain the good bulk acoustic wave resonator of thermal diffusivity becomes the technical issues of urgently this field solves.
Summary of the invention
The technical problem to be solved by the present invention is to improve the heat dissipation performances of bulk acoustic wave resonator.
To solve the above-mentioned problems, the present invention provides a kind of manufacturing methods of bulk acoustic wave resonator comprising: it provides
Substrate；Several spaced holes are formed on the surface of the substrate；Be heat-treated so that several holes be merged into
A few hanging closed cavity；Being formed over the substrate, there is the piezoelectricity of opening to shake stack layers；To being exposed to the opening
Substrate carry out isotropic etching, continue after being etched to the closed cavity to the substrate around the closed cavity into
The row isotropic etching, to form the cavity with the open communication, at least partly described pressure on the surface of the substrate
Electroshock is swung stack layers and is located on the cavity.
Optionally, the heat treatment is rapid thermal annealing.
Optionally, the temperature of the heat treatment is not less than 1100 degrees Celsius.
Optionally, the closed cavity is merged by heat treatment several spaced holes.
Optionally, more than two spaced institutes are merged by heat treatment several spaced holes
State closed cavity.
Optionally, the ratio between the width at the interval between the two neighboring hole and hole is greater than 2.
Optionally, the isotropic etching is dry etching.
Optionally, it includes: in the substrate that being formed over the substrate, which has the method for the piezoelectricity concussion stack layers of opening,
Surface forms the lower metal layer, piezoelectric thin film layer and the upper metal layer that stack gradually, under the lower metal layer includes locally connected
Electrode and lower connecting component, the upper metal layer includes locally connected top electrode and upper connecting component, perpendicular to the lining
On the direction at bottom, the projection of the lower electrode, top electrode is overlapped with the projection of the closed cavity, the lower connecting component,
Projection of the projection of upper connecting component with the closed cavity is staggered；The piezoelectric thin film layer is performed etching to be formed
State opening.
Optionally, while forming the opening, the contact hole across the piezoelectric thin film layer, the contact are formed
Expose the lower connecting component in hole；Before carrying out the isotropic etching, it is respectively formed and the lower connecting component, upper company
Lower metal pad, the upper metal pad of relay part electrical connection.
Optionally, the upper connecting component, lower connecting component are arranged in the two sides of the top electrode, lower electrode.
Optionally, the opening is tool ring-type jaggy.
In addition, the present invention also provides a kind of bulk acoustic wave resonators comprising: substrate, surface have isotropic etching
Chamber；Stack layers are shaken positioned at the piezoelectricity with opening of the substrate, the opening connects with the isotropic etching chamber
Logical, at least partly described piezoelectricity concussion stack layers are located on the isotropic etching chamber.
Optionally, the isotropic etching chamber carries out isotropism by the inner wall to the closed cavity in the substrate
It etches, the closed cavity is merged by several spaced holes are thermally treated.
Optionally, the heat treatment is rapid thermal annealing.
Optionally, the isotropic etching is dry etching.
Optionally, the piezoelectricity concussion stack layers include: the lower metal layer stacked gradually, piezoelectric thin film layer and upper metal layer；
The lower metal layer includes locally connected lower electrode and lower connecting component；The upper metal layer includes locally connected powers on
Pole and upper connecting component；On the direction perpendicular to the substrate, the lower electrode, top electrode projection with it is described respectively to
The projection of same sex etch chamber is overlapped, the lower connecting component, upper connecting component projection with the isotropic etching chamber
Projection is staggered；The opening is across the piezoelectric thin film layer.
Optionally, the upper connecting component, lower connecting component are arranged in the two sides of the top electrode, lower electrode.
Optionally, further includes: upper metal pad, lower metal pad on the piezoelectric thin film layer；The upper gold
Belong to pad to be located on the upper connecting component, and is electrically connected the upper connecting component；The lower metal pad be located at it is described under
On connecting component, and it is electrically connected the lower connecting component.
Optionally, the opening is tool ring-type jaggy.
The present invention first forms closed cavity in substrate, then to the substrate of the opening being exposed in piezoelectricity concussion stack layers into
Row isotropic etching continues to carry out isotropic etching to the substrate around closed cavity after being etched to closed cavity,
Etch rate not only can be greatly improved, process costs are reduced, bigger cavity can also be obtained in substrate surface, with
It is more advantageous to heat dissipation.Further, the housing surface formed using the isotropic etching technique is more smooth, is used as sound
Wave reflection interface, quality factor height, good reliability.
Detailed description of the invention
Fig. 1 is a kind of structural schematic diagram of existing silicon reverse side etching type bulk acoustic wave resonator；
Fig. 2 is the structural schematic diagram of existing another air type bulk acoustic wave resonator；
Fig. 3 to Figure 11 is sectional view of the bulk acoustic wave resonator in the different fabrication stages in the first embodiment of the present invention,
In, Fig. 4 is the top view of Fig. 3, and Figure 11 is the top view of Figure 10；
Figure 12 be in the second embodiment of the present invention bulk acoustic wave resonator in the top view of a wherein fabrication stage；
Figure 13 be in the third embodiment of the present invention bulk acoustic wave resonator in the top view of a wherein fabrication stage；
Figure 14 to Figure 15 be in the fourth embodiment of the present invention bulk acoustic wave resonator in the section of wherein two fabrication stages
Figure.
Specific embodiment
First embodiment
First the specific embodiment of bulk acoustic wave resonator manufacturing method provided by the invention is done in detail with reference to the accompanying drawing
Explanation.
As shown in figure 3, providing substrate 301.In the present embodiment, substrate 301 is monocrystalline substrate.Certainly, in other realities
It applies in example, substrate 301 can also select other suitable semiconductor materials.
With continued reference to several spaced holes 302 shown in Fig. 3, are formed in substrate 301, define adjacent two hole 302 it
Between part be figure 303.In the present embodiment, the forming method in hole 302 includes:
Patterned protective layer (not shown) is formed on the surface of substrate 301, the manufacturing method packet of the patterned protective layer
It includes: using techniques such as low-pressure chemical vapor deposition, plasma activated chemical vapour deposition or thermal oxides in the upper surface of substrate 301
It is formed after the protected material bed of material (not shown), then using photoetching and wet corrosion technique or photoetching and dry etch process
The part protected material bed of material is removed, patterned protective layer is formed.In the specific embodiment, the material of protective layer is oxidation
Silicon, in other specific embodiments of the invention, the material of protective layer can also be silicon nitride, silicon carbide, silicon oxynitride etc.
Dielectric material can be single-layer or multi-layer composite construction.
Using the patterned protective layer as exposure mask, substrate 301 is performed etching, to form several holes 302.The specific reality
It applies in mode, is obtained using anisotropic etch process, such as deep reactive ion silicon etching (DRIE) technique, etched substrate 301
Several holes 302.In the present embodiment, the depth in hole 302 is 5um~10um.
It is formed after hole 302, removes the patterned protective layer.In a particular embodiment, rotten using dry etching or wet process
Etching technique such as removes the patterned protective layer with buffered hydrofluoric acid (BOE).
Fig. 4 is the top view of Fig. 3, as shown in figure 4, in the present embodiment, several holes 302 are arranged in array, hole 302 is
Strip.Certainly, in other embodiments, hole 302 may be set to be the hole of other shapes, which can be rectangle, circle
Shape, pentagon, hexagon or other polygons.The width for defining hole 302 is R1, and the width between two neighboring hole 302 is (i.e.
The width of figure 303) it is R2, R1, R2's is typically sized within 10um, and R1 can be equal with R2, can not also wait.At this
In embodiment, R1 and R2 are equal.
As shown in figure 5, being heat-treated to substrate 301, so that several holes 302 (referring to Fig. 4) are merged into hanging closing
Cavity 401, it is so-called vacantly to refer to that closed cavity 401 is located at the inside of substrate 301, exist centainly with the upper surface of substrate 301
Interval.
In conjunction with shown in Fig. 4 to Fig. 5, under the action of the heat treatment, cause the diffusion into the surface silicon mechanism of substrate, that is, hole
302 can expand in the horizontal direction, so that merging between adjacent hole 302, to form bigger cavity.At the same time, in institute
Under the action of stating heat treatment, the upper surface energy of substrate 301 is reduced, so that the upper surface of substrate 301 migrates, Ge Getu
The end of shape 303 is able to be combined with each other as an entirety, so that free standing structure film 402 is formed in the top of the cavity, in substrate
301 inside forms closed cavity 401.The free standing structure film 402 formed by the heat treatment process is very smooth, and thinner thickness,
It can be as thin as 1 micron.In a particular embodiment, closed cavity 401 is located at the center position on the upper side inside substrate 301.
It should be noted that the thickness of the quantity of the closed cavity 401 formed under the thermal processes act, free standing structure film 402
Width R2 between degree and the width R1 in hole 302, two neighboring hole 302 is related, in the present embodiment, since R1 is equal to R2,
Therefore a bigger closed cavity 402 is merged into all holes 302 in substrate 301.
Specifically, the heat treatment carries out in the environment of not oxygen-containing, low pressure (subatmospheric), to prevent substrate 301
It is oxidized.In one embodiment, which is pure hydrogen environment.Certainly, in other embodiments, this is not oxygen-containing
Environment may be inert gas environment.
In the present embodiment, 1100 degrees Celsius of the temperature of the heat treatment.Certainly, in other embodiments, at the heat
The temperature of reason can also be higher than 1100 degrees Celsius.Further, in the present embodiment, the heat treatment is rapid thermal annealing.
As shown in fig. 6, forming lower metal layer (not identifying) on the surface of substrate 301.The lower metal layer includes Local Phase
Lower electrode 501a and lower connecting component 501b even.In the present embodiment, the forming method of lower metal layer 501 includes: in substrate
Metal material layer is formed on 301；The metal material layer is patterned, to obtain locally connected lower electrode 501a under
Connecting component 501b.In the present embodiment, the material of lower metal layer includes the metal materials such as aluminium, molybdenum, palladium, titanium.Preferably, under
The material of metal layer is molybdenum or palladium, because it has good crystallization compatible with the c-axis direction for the piezoelectric thin film layer being subsequently formed
Property, and better crystalline quality and crystallite dimension can be provided.In the present embodiment, lower metal layer with a thickness of 200~500nm.
As shown in fig. 7, forming piezoelectric thin film layer 601 on substrate 301 and lower metal layer.In the present embodiment, piezoelectricity is thin
The material of film layer 601 is aluminium nitride (AlN) or zinc oxide (ZnO), and the c-axis along crystal is grown.The thickness of piezoelectric thin film layer 601
Degree is negatively correlated with frequency, and crystal quality is also closely related with the performance of resonator.The efficient coupling of piezoelectric thin film layer 601
The bandwidth of coefficient and resonator is positively correlated, for improve effective coupling coefficient, can be adulterated into piezoelectric thin film layer 601 trivalent,
Divalent, tetravalent metal elements, such as scandium, calcium-titanium, magnesium-titanium, calcium-zirconium.In the present embodiment, the thickness of piezoelectric thin film layer 601
For 0.5nm~2um.
As shown in fig. 7, forming upper metal layer (not identifying) on piezoelectric thin film layer 601.The upper metal layer includes part
Connected top electrode 602a and upper connecting component 602b.In the present embodiment, the forming method of upper metal layer includes: in piezoelectricity
Metal material layer is formed in film layer 601；The metal material layer is patterned, to obtain locally connected top electrode
602a and upper connecting component 602b.In the present embodiment, the material of upper metal layer includes the metal materials such as aluminium, molybdenum, palladium, titanium.?
In the present embodiment, upper metal layer with a thickness of 200~500nm.
On the direction perpendicular to the substrate 301, the lower electrode 501a, top electrode 602a projection with it is described
The projection of closed cavity 401 is overlapped, the lower connecting component 501b, upper connecting component 602b projection with the closing chamber
The projection of body 401 is staggered, and upper connecting component 602b, lower connecting component 501b are arranged in the top electrode 602a, lower electricity
The two sides of pole 501a.
As shown in figure 8, being performed etching to the piezoelectric thin film layer 601 to form the opening 701.In the present embodiment,
Opening 701 is in having cyclic annular (i.e. opening 701 is similar to C font, not surround in 360 degree) jaggy, so that piezoelectricity shakes heap
Heap is shaken for piezoelectricity by the circular part of opening 701 in layer.
In the present embodiment, 701 forming method of being open includes: to form covering piezoelectric thin film layer 601 and upper metal layer
Patterned masking layer, the Patterned masking layer can be photoresist；Using the Patterned masking layer as exposure mask, to piezoelectric thin film layer
601 perform etching, to form opening 701 in piezoelectric thin film layer 601；It is formed after opening 701, removes the pattern mask
Layer, minimizing technology can be ashing.
In the present embodiment, while forming opening 701, the contact hole across the piezoelectric thin film layer 601 is formed
703, the contact hole 703 exposes the lower connecting component 501b.
As shown in figure 9, being respectively formed the lower metal pad being electrically connected with lower connecting component 501b, upper connecting component 602b
801, upper metal pad 802.Wherein, a part of lower metal pad 801 protrudes into contact hole 703 (with reference to Fig. 8), and under
Connecting component 501b forms Ohmic contact.
As shown in Figures 9 to 11, isotropic etching is carried out to the substrate 301 for being exposed to the opening 701, works as etching
To after the closed cavity 401, continuing to carry out isotropic etching to the substrate 301 around the closed cavity 401, with
The surface of the substrate 301 forms the cavity (also referred to as isotropic etching chamber) 901 being connected to the opening 701.Piezoelectricity
Concussion heap is suspended on cavity 901, can be moved along the direction perpendicular to substrate 301, in the effect by external force
Deformation occurs.
Specifically, when carrying out the isotropic etching, protective layer (not shown) is formed in the position except opening 701.
In a particular embodiment, which is photoresist.Then, the part that opening 701 is exposed in substrate 301 is performed etching,
To form the groove (not identifying) for being aligned and being connected to opening 701 in substrate 301, when the envelope for being etched to the groove and lower section
When closed chamber body 401 is connected to, used etching agent is full of closed cavity 401, and (i.e. to the substrate 301 around closed cavity 401
The cavity wall of closed cavity 401) isotropic etching is carried out, so that closed cavity 401 is in all directions by rapid expansion,
Until the underlayer surface right above closed cavity 401 is removed, the chamber being connected to opening 701 is formed on the surface of substrate 301
Body 901.
In the present embodiment, the isotropic etching is dry etching.Specifically, the etching gas includes XeF2。
XeF2There is very high Etch selectivity to silicon as etching gas, it is very fast to the etch rate of silicon, 1~3 μ can be reached
Etching efficiency can be improved in m/min.
In the inventive solutions, closed cavity is first formed in substrate, then is shaken in stack layers piezoelectricity is exposed to
Opening substrate carry out isotropic etching, after being etched to closed cavity, continue to around closed cavity substrate carry out
Isotropic etching not only can greatly improve etch rate, reduce process costs, can also obtain in substrate surface
Bigger cavity, to be more advantageous to heat dissipation.Further, more using the housing surface of isotropic etching technique formation
It is smooth, it is used as sound wave reflecting interface, quality factor height, good reliability.
It describes in detail below to the structure of the bulk acoustic wave resonator of the present embodiment.
As shown in Figure 10 to Figure 11, which includes substrate 301, and the surface of substrate 301 has isotropism
Etch chamber (being formed by chamber using isotropic etching technique removal section substrate) 901.It is arranged on the substrate 301
There is piezoelectricity concussion stack layers (not identifying) with opening 701, the opening 701 is connected to the isotropic etching chamber 901,
The piezoelectricity concussion stack layers are located at the isotropic etching by the circular part of opening 701 (also referred to as piezoelectricity concussion heap)
On chamber 901, and it can be moved along the direction perpendicular to substrate 301.
Further, isotropic etching chamber 901 to the closed cavity in the substrate 301 inner wall carry out it is each to
The same sex etches, and the closed cavity is merged by several spaced holes are thermally treated.By to substrate 301 into
Row heat treatment, so that several holes are merged into hanging closed cavity, it is so-called vacantly to refer to that closed cavity is located at the interior of substrate 301
Portion, there are certain intervals with the upper surface of substrate 301.
Under the action of the heat treatment, cause the diffusion into the surface silicon mechanism of substrate, that is, the hole in substrate can be along level
Direction expands, so that merging between adjacent hole, to form bigger cavity.At the same time, in the effect of the heat treatment
Under, the upper surface energy of substrate 301 reduces, so that the upper surface of substrate 301 migrates, the end of the figure between each hole
Portion is able to be combined with each other and be formed to form free standing structure film in the top of the cavity in the inside of substrate 301 for an entirety
Closed cavity.The free standing structure film formed by the heat treatment process is very smooth, and thinner thickness, can be as thin as 1 micron.Having
In body embodiment, closed cavity is located at the center position on the upper side inside substrate 301.
Specifically, the heat treatment carries out in the environment of not oxygen-containing, low pressure (subatmospheric), to prevent substrate 301
It is oxidized.In one embodiment, which is pure hydrogen environment.Certainly, in other embodiments, this is not oxygen-containing
Environment may be inert gas environment.
In the present embodiment, 1100 degrees Celsius of the temperature of the heat treatment.Certainly, in other embodiments, at the heat
The temperature of reason can also be higher than 1100 degrees Celsius.Further, in the present embodiment, the heat treatment is rapid thermal annealing.
In substrate 301 formed closed cavity after, using etching agent be full of closed cavity, and to closed cavity around
Substrate 301 (i.e. the cavity wall of closed cavity 401) carry out isotropic etching so that closed cavity 401 in all directions
By rapid expansion, until the underlayer surface right above closed cavity 401 is removed, to form isotropic etching chamber.
Further, the isotropic etching is dry etching.Specifically, the etching gas includes XeF2。
The piezoelectricity concussion stack layers include the lower metal layer stacked gradually, piezoelectric thin film layer 601 and upper metal layer.It is described
Lower metal layer includes locally connected lower electrode 501a and lower connecting component 501b.In the present embodiment, the material of lower metal layer
Including metal materials such as aluminium, molybdenum, palladium, titaniums.Preferably, the material of lower metal layer is molybdenum or palladium, because of itself and piezoelectric thin film layer
There is crystallization compatibility well in 601 c-axis direction, and can provide better crystalline quality and crystallite dimension.In the present embodiment
In, lower metal layer with a thickness of 200~500nm.
In the present embodiment, the material of piezoelectric thin film layer 601 is aluminium nitride (AlN) or zinc oxide (ZnO), along crystalline substance
The c-axis of body is grown.The thickness of piezoelectric thin film layer 601 and frequency are negatively correlated, and crystal quality is also close with the performance of resonator
It is related.The effective coupling coefficient of piezoelectric thin film layer 601 and the bandwidth of resonator are positively correlated, can to improve effective coupling coefficient
To adulterate trivalent, divalent, tetravalent metal elements, such as scandium, calcium-titanium, magnesium-titanium, calcium-zirconium into piezoelectric thin film layer 601.At this
In embodiment, piezoelectric thin film layer 601 with a thickness of 0.5nm~2um.
The upper metal layer includes locally connected top electrode 602a and upper connecting component 602b.In the present embodiment, on
The material of metal layer includes the metal materials such as aluminium, molybdenum, palladium, titanium.In the present embodiment, upper metal layer with a thickness of 200~
500nm。
On the direction perpendicular to the substrate 301, the lower electrode 501a, top electrode 602a projection with it is described
The projection of isotropic etching chamber 901 is overlapped, the lower connecting component 501b, upper connecting component 602b projection with it is described
The projection of isotropic etching chamber 901 is staggered, and upper connecting component 602b, lower connecting component 501b are arranged on described
The two sides of electrode 602a, lower electrode 501a.
In the present embodiment, in having ring-type jaggy, (i.e. opening 701 is similar to C font to opening 701, is not in 360
Degree is surround) so that shaking heap by the circular part of opening 701 in piezoelectricity concussion stack layers for piezoelectricity.
Metal pad 802, lower metal pad 801 are formed on piezoelectric thin film layer 601.Wherein, the upper metal welding
Disk 802 is located on the upper connecting component 602b, and is electrically connected the upper connecting component 602b.The lower metal pad 801
On the lower connecting component 501b, and it is electrically connected the lower connecting component 501b.A part of lower metal pad 801
It protrudes into the contact hole (not identifying) being arranged in piezoelectric thin film layer 601, and forms Ohmic contact with lower connecting component 501b.
Second embodiment
Difference between the present embodiment and first embodiment is: as shown in figure 12, in the present embodiment, in substrate 301
Several holes 302 be circle, all circular holes in rule array arrangement.
3rd embodiment
Difference between the present embodiment and first embodiment is: as shown in figure 13, in the present embodiment, in substrate 301
Several holes 302 be regular hexagon, all hexagonal holes in rule array arrangement.
Fourth embodiment
Difference between the present embodiment and first embodiment is: as shown in figure 14, in the present embodiment, defining hole 302
Width be R1, the width (i.e. the width of figure 303) between two neighboring hole 302 is R2, and the ratio between R2 and R1 are greater than 2.As before
It is described, the quantity of the closed cavity 401 formed under the thermal processes act and width R1, the two neighboring hole 302 in hole 302
Between width R2 it is related, in the present embodiment, due to the ratio between R2 and R1 be greater than 2, therefore, to the substrate for being formed with hole 302
301 carry out under process of thermal treatment, and more than two spaced closings are merged into all holes 302 in substrate 301
Cavity 401.
In conjunction with shown in Figure 14 to Figure 15, it is subsequent through to piezoelectricity concussion stack layers in opening to substrate 301 carry out it is each to
The same sex etch when, after being etched to closed cavity 401, continue to around the closed cavity 401 substrate 301 (including
Part between two neighboring closed cavity 401) isotropic etching is carried out, the surface shape in the substrate 301 is remained in this way
At the cavity (also referred to as isotropic etching chamber) with the open communication, dotted portion is indicated at this respectively to same in Figure 15
The part that substrate is removed in property etching technics.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
Member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications should also regard
For protection scope of the present invention.
Claims (19)
1. a kind of manufacturing method of bulk acoustic wave resonator characterized by comprising
Substrate is provided；
Several spaced holes are formed on the surface of the substrate；
It is heat-treated, so that several holes are merged at least one hanging closed cavity；
Being formed over the substrate, there is the piezoelectricity of opening to shake stack layers；
Isotropic etching is carried out to the substrate for being exposed to the opening, is continued after being etched to the closed cavity to the envelope
Substrate around closed chamber body carries out the isotropic etching, to form the chamber with the open communication on the surface of the substrate
Body, at least partly described piezoelectricity concussion stack layers are located on the cavity.
2. the manufacturing method according to claim 1, which is characterized in that the heat treatment is rapid thermal annealing.
3. the manufacturing method according to claim 1, which is characterized in that the temperature of the heat treatment is Celsius not less than 1100
Degree.
4. the manufacturing method according to claim 1, which is characterized in that described several spaced by the heat treatment
The closed cavity is merged into hole.
5. the manufacturing method according to claim 1, which is characterized in that described several spaced by the heat treatment
More than two spaced closed cavities are merged into hole.
6. manufacturing method according to claim 5, which is characterized in that interval and hole between the two neighboring hole
The ratio between width be greater than 2.
7. the manufacturing method according to claim 1, which is characterized in that the isotropic etching is dry etching.
8. manufacturing method according to any one of claims 1 to 7, which is characterized in that formed to have over the substrate and be opened
Mouthful piezoelectricity concussion stack layers method include:
Lower metal layer, piezoelectric thin film layer and the upper metal layer stacked gradually, the lower metal layer are formed on the surface of the substrate
It include locally connected top electrode and upper interconnecting piece including locally connected lower electrode and lower connecting component, the upper metal layer
Part, on the direction perpendicular to the substrate, the lower electrode, top electrode projection with the projection weight of the closed cavity
It closes, projection of the projection of the lower connecting component, upper connecting component with the closed cavity is staggered；
The piezoelectric thin film layer is performed etching to form the opening.
9. manufacturing method according to claim 8, which is characterized in that while forming the opening, formed across institute
The contact hole of piezoelectric thin film layer is stated, the contact hole exposes the lower connecting component；
Before carrying out the isotropic etching, it is respectively formed the lower gold being electrically connected with the lower connecting component, upper connecting component
Belong to pad, upper metal pad.
10. manufacturing method according to claim 8, which is characterized in that the upper connecting component, lower connecting component distinguish cloth
It sets in the two sides of the top electrode, lower electrode.
11. manufacturing method according to claim 8, which is characterized in that the opening is tool ring-type jaggy.
12. a kind of bulk acoustic wave resonator characterized by comprising
Substrate, surface have isotropic etching chamber；
Stack layers are shaken positioned at the piezoelectricity with opening of the substrate, the opening connects with the isotropic etching chamber
Logical, at least partly described piezoelectricity concussion stack layers are located on the isotropic etching chamber.
13. bulk acoustic wave resonator according to claim 12, which is characterized in that the isotropic etching chamber is by described
The inner wall of closed cavity in substrate carries out isotropic etching and forms, and the closed cavity is by several spaced Kong Jingre
Processing merges.
14. bulk acoustic wave resonator according to claim 13, which is characterized in that the heat treatment is rapid thermal annealing.
15. bulk acoustic wave resonator according to claim 13, which is characterized in that the isotropic etching is dry method quarter
Erosion.
16. bulk acoustic wave resonator according to claim 12 or 13, which is characterized in that the piezoelectricity shakes stack layers and includes:
Lower metal layer, piezoelectric thin film layer and the upper metal layer stacked gradually；
The lower metal layer includes locally connected lower electrode and lower connecting component；
The upper metal layer includes locally connected top electrode and upper connecting component；
On the direction perpendicular to the substrate, the lower electrode, top electrode projection with the isotropic etching chamber
Projection is overlapped, and projection of the projection of the lower connecting component, upper connecting component with the isotropic etching chamber is staggered；
The opening is across the piezoelectric thin film layer.
17. bulk acoustic wave resonator according to claim 16, which is characterized in that the upper connecting component, lower connecting component
It is arranged in the two sides of the top electrode, lower electrode.
18. bulk acoustic wave resonator according to claim 16, which is characterized in that further include:
Upper metal pad, lower metal pad on the piezoelectric thin film layer；
The upper metal pad is located on the upper connecting component, and is electrically connected the upper connecting component；
The lower metal pad is located on the lower connecting component, and is electrically connected the lower connecting component.
19. bulk acoustic wave resonator according to claim 12, which is characterized in that the opening is tool ring-type jaggy.
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| PCT/CN2019/112936 WO2020206982A1 (en) | 2019-04-08 | 2019-10-24 | Bulk acoustic resonator and manufacturing method thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2020206982A1 (en) * | 2019-04-08 | 2020-10-15 | 苏州敏芯微电子技术股份有限公司 | Bulk acoustic resonator and manufacturing method thereof |
| CN112787614A (en) * | 2019-11-11 | 2021-05-11 | 上海珏芯光电科技有限公司 | Thin film lamb wave resonator, filter and manufacturing method thereof |
| WO2021102813A1 (en) * | 2019-11-28 | 2021-06-03 | 华为技术有限公司 | Film bulk acoustic resonator and preparation method therefor, and filter |
| CN116054775A (en) * | 2022-11-09 | 2023-05-02 | 天通瑞宏科技有限公司 | Preparation method of acoustic wave device and acoustic wave device |
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| US7385334B1 (en) * | 2006-11-20 | 2008-06-10 | Sandia Corporation | Contour mode resonators with acoustic reflectors |
| CN203200012U (en) * | 2013-02-19 | 2013-09-18 | 苏州敏芯微电子技术有限公司 | Micro electromechanical system sensor |
| CN209787132U (en) * | 2019-04-08 | 2019-12-13 | 苏州敏芯微电子技术股份有限公司 | Bulk acoustic wave resonator |
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| CN110198158A (en) * | 2019-04-08 | 2019-09-03 | 苏州敏芯微电子技术股份有限公司 | Bulk acoustic wave resonator and its manufacturing method |
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2019
- 2019-04-08 CN CN201910276219.7A patent/CN110198158A/en active Pending
- 2019-10-24 WO PCT/CN2019/112936 patent/WO2020206982A1/en active Application Filing
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| US7385334B1 (en) * | 2006-11-20 | 2008-06-10 | Sandia Corporation | Contour mode resonators with acoustic reflectors |
| CN203200012U (en) * | 2013-02-19 | 2013-09-18 | 苏州敏芯微电子技术有限公司 | Micro electromechanical system sensor |
| CN209787132U (en) * | 2019-04-08 | 2019-12-13 | 苏州敏芯微电子技术股份有限公司 | Bulk acoustic wave resonator |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020206982A1 (en) * | 2019-04-08 | 2020-10-15 | 苏州敏芯微电子技术股份有限公司 | Bulk acoustic resonator and manufacturing method thereof |
| CN112787614A (en) * | 2019-11-11 | 2021-05-11 | 上海珏芯光电科技有限公司 | Thin film lamb wave resonator, filter and manufacturing method thereof |
| WO2021102813A1 (en) * | 2019-11-28 | 2021-06-03 | 华为技术有限公司 | Film bulk acoustic resonator and preparation method therefor, and filter |
| CN116054775A (en) * | 2022-11-09 | 2023-05-02 | 天通瑞宏科技有限公司 | Preparation method of acoustic wave device and acoustic wave device |
| CN116054775B (en) * | 2022-11-09 | 2023-08-04 | 天通瑞宏科技有限公司 | Preparation method of acoustic wave device and acoustic wave device |
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