WO2020206982A1 - 体声波谐振器及其制造方法 - Google Patents

体声波谐振器及其制造方法 Download PDF

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Publication number
WO2020206982A1
WO2020206982A1 PCT/CN2019/112936 CN2019112936W WO2020206982A1 WO 2020206982 A1 WO2020206982 A1 WO 2020206982A1 CN 2019112936 W CN2019112936 W CN 2019112936W WO 2020206982 A1 WO2020206982 A1 WO 2020206982A1
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Prior art keywords
substrate
cavity
piezoelectric
isotropic etching
manufacturing
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PCT/CN2019/112936
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English (en)
French (fr)
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李刚
吕萍
胡维
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苏州敏芯微电子技术股份有限公司
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Publication of WO2020206982A1 publication Critical patent/WO2020206982A1/zh

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    • 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

Definitions

  • the present invention relates to the field of Micro-Electro-Mechanical System (MEMS for short), in particular to a bulk acoustic wave resonator and a manufacturing method thereof.
  • MEMS Micro-Electro-Mechanical System
  • the quality of the RF signal depends on the RF filter in the mobile phone, and the acoustic resonator is the basic component of the RF filter and sensor.
  • radio frequency filters dielectric filters, surface acoustic wave (SAW) resonators and film bulk acoustic wave resonators (FBAR).
  • SAW surface acoustic wave
  • FBAR film bulk acoustic wave resonators
  • the dielectric filter is covered with a metal layer used as an electric wall on its surface.
  • the electromagnetic wave is confined in the medium to form a standing wave oscillation. Its main advantages are large power capacity and low insertion loss, but it is large in size and difficult to integrate.
  • the surface acoustic wave resonator uses photolithography to form input and output interdigital electrodes on the upper surface of its piezoelectric substrate (such as lithium niobate, etc.), and uses the piezoelectric effect to excite the surface acoustic wave and detect the output.
  • the surface acoustic wave resonator is smaller in size than the dielectric filter, but its insertion loss is large, and it is restricted by the photolithography technology.
  • the operating frequency is low, the power capacity is low, and it is difficult to integrate.
  • the performance of the bulk acoustic wave resonator surpasses the dielectric filter and the surface wave resonator completely.
  • the frequency is determined by the thickness of the piezoelectric layer, so the frequency can be much higher than that of the surface wave resonator, and it is small in size, low in insertion loss, and out-of-band. Good suppression, high power capacity, and easy integration. Therefore, the bulk acoustic wave resonator is a research hotspot in recent years.
  • FIG. 1 is a schematic diagram of the structure of a conventional bulk acoustic wave resonator with silicon back etching.
  • the bulk acoustic wave resonator 100 includes a silicon substrate 101 with a back-etched cavity 102, a support layer 103 stacked on the silicon substrate 101, a lower electrode 104, a piezoelectric layer 105, and an upper electrode. 106.
  • the bottom electrode 104, the piezoelectric layer 105, and the top electrode 106 form a sandwich structure, which is also called a piezoelectric oscillatory stack.
  • the resonator 100 uses the MEMS bulk silicon micro-manufacturing process to etch and remove most of the silicon material from the reverse side of the silicon wafer to form an air interface on the lower surface of the piezoelectric oscillating stack, thereby confining sound waves within the piezoelectric oscillating stack. This can better solve the heat dissipation problem and effectively reduce the sound leakage, but its structural stability is poor.
  • FIG. 2 is a schematic diagram of another existing air-type bulk acoustic wave resonator.
  • the resonator 200 includes a silicon substrate 201 with an air gap cavity 202, a support layer 203, a lower electrode 204, a piezoelectric layer 205, and an upper electrode 206 stacked on the silicon substrate 201 in sequence.
  • the bottom electrode 204, the piezoelectric layer 205, and the top electrode 206 form a sandwich structure, also called a piezoelectric oscillatory stack.
  • the resonator 200 first etches the air gap cavity 202 through the DRIE process, then deposits the sacrificial layer material (such as phosphosilicate glass), then performs chemical mechanical polishing (CMP) on the sacrificial layer material, and finally releases it to expose the air gap
  • the cavity 202 forms an air interface on the lower surface of the piezoelectric oscillating stack, thereby confining sound waves within the piezoelectric oscillating stack.
  • This structure can effectively prevent sound leakage and has good stability, but the heat dissipation is not smooth, and the process involves the growth, CMP and release of the sacrificial layer material, and the process is difficult and the equipment is expensive.
  • the technical problem to be solved by the present invention is to improve the heat dissipation performance of the bulk acoustic wave resonator.
  • the present invention provides a method for manufacturing a bulk acoustic wave resonator, which includes: providing a substrate; forming a plurality of spaced holes on the surface of the substrate; and performing heat treatment to make the plurality of holes merge into At least one suspended closed cavity; forming a piezoelectric oscillating stack layer with an opening on the substrate; isotropic etching is performed on the substrate exposed to the opening, and when the closed cavity is etched Continue to perform the isotropic etching on the substrate around the closed cavity to form a cavity connected to the opening on the surface of the substrate, and at least part of the piezoelectric oscillation stack is located in the Above the cavity.
  • the heat treatment is rapid thermal annealing.
  • the temperature of the heat treatment is not less than 1100 degrees Celsius.
  • the several spaced holes are combined into one closed cavity.
  • the several spaced holes are merged into two or more spaced closed cavities.
  • the ratio of the interval between the two adjacent holes to the width of the hole is greater than 2.
  • the isotropic etching is dry etching.
  • the method for forming a piezoelectric oscillating layer with openings on the substrate includes: forming a lower metal layer, a piezoelectric thin film layer, and an upper metal layer sequentially stacked on the surface of the substrate, and the lower The metal layer includes a partially connected lower electrode and a lower connecting member, and the upper metal layer includes a partially connected upper electrode and an upper connecting member.
  • the projections of the lower electrode and the upper electrode are both It coincides with the projection of the closed cavity, and the projections of the lower connection part and the upper connection part are all staggered with the projection of the closed cavity; the piezoelectric film layer is etched to form the opening.
  • a contact hole is formed through the piezoelectric film layer, and the contact hole exposes the lower connecting member; before the isotropic etching is performed, a The lower connecting component, the lower metal pad and the upper metal pad electrically connected to the upper connecting component are described.
  • the upper connection part and the lower connection part are respectively arranged on both sides of the upper electrode and the lower electrode.
  • the opening has a ring shape with a gap.
  • the present invention also provides a bulk acoustic wave resonator, which includes: a substrate with an isotropic etching cavity on the surface; a piezoelectric oscillatory stack layer with openings on the substrate, the openings and The isotropic etching cavity is connected, and at least a part of the piezoelectric oscillatory stack is located on the isotropic etching cavity.
  • the isotropic etching cavity is formed by isotropically etching the inner wall of a closed cavity in the substrate, and the closed cavity is formed by combining a plurality of spaced holes after heat treatment. .
  • the heat treatment is rapid thermal annealing.
  • the isotropic etching is dry etching.
  • the piezoelectric oscillating layer includes: a lower metal layer, a piezoelectric thin film layer, and an upper metal layer stacked in sequence; the lower metal layer includes a lower electrode and a lower connecting member that are locally connected; the upper metal layer It includes a partially connected upper electrode and an upper connecting part; in a direction perpendicular to the substrate, the projections of the lower electrode and the upper electrode coincide with the projections of the isotropic etching cavity, and the lower connecting part The projections of the upper connecting parts are all staggered with the projections of the isotropic etching cavity; the opening passes through the piezoelectric film layer.
  • the upper connection part and the lower connection part are respectively arranged on both sides of the upper electrode and the lower electrode.
  • it further includes: an upper metal pad and a lower metal pad located on the piezoelectric film layer; the upper metal pad is located on the upper connecting member and electrically connected to the upper connecting member The lower metal pad is located on the lower connecting part and is electrically connected to the lower connecting part.
  • the opening has a ring shape with a gap.
  • the present invention first forms a closed cavity in the substrate, and then performs isotropic etching on the substrate exposed to the openings in the piezoelectric oscillatory stack. After etching to the closed cavity, continues to The substrate is etched isotropically, which can not only greatly increase the etching rate and reduce the process cost, but also obtain a larger cavity on the surface of the substrate, which is more conducive to heat dissipation. Further, the surface of the cavity formed by the isotropic etching process is smoother, which serves as an acoustic wave reflection interface with high quality factor and good reliability.
  • FIG. 1 is a schematic diagram of the structure of a conventional bulk acoustic wave resonator with silicon reverse side etching
  • Fig. 2 is a schematic structural diagram of another existing air-type bulk acoustic wave resonator
  • FIG. 3 to 11 are cross-sectional views of the bulk acoustic wave resonator in different manufacturing stages in the first embodiment of the present invention, wherein FIG. 4 is a top view of FIG. 3, and FIG. 11 is a top view of FIG. 10;
  • Figure 12 is a top view of the bulk acoustic wave resonator in one of the manufacturing stages of the second embodiment of the present invention.
  • FIG. 13 is a top view of the bulk acoustic wave resonator in one of the manufacturing stages of the third embodiment of the present invention.
  • 14 to 15 are cross-sectional views of the bulk acoustic wave resonator in two manufacturing stages of the fourth embodiment of the present invention.
  • a substrate 301 is provided.
  • the substrate 301 is a single crystal silicon substrate.
  • the substrate 301 can also be selected from other suitable semiconductor materials.
  • a number of holes 302 arranged at intervals are formed in the substrate 301, and the portion between two adjacent holes 302 is defined as a pattern 303.
  • the method for forming the hole 302 includes:
  • a patterned protective layer (not shown) is formed on the surface of the substrate 301.
  • the manufacturing method of the patterned protective layer includes: using low-pressure chemical vapor deposition, plasma chemical vapor deposition or thermal oxidation processes on the upper surface of the substrate 301 After the protective material layer (not shown) is formed, photolithography and wet etching processes, or photolithography and dry etching processes are then used to remove part of the protective material layer to form a patterned protective layer.
  • the material of the protective layer is silicon oxide.
  • the material of the protective layer can also be a dielectric material such as silicon nitride, silicon carbide, silicon oxynitride, etc., which can be a single layer or Multi-layer composite structure.
  • the substrate 301 is etched to form a plurality of holes 302.
  • an anisotropic etching process such as a deep reactive ion silicon etching (DRIE) process, is used to etch the substrate 301 to obtain a plurality of holes 302.
  • the depth of the hole 302 is 5um-10um.
  • the patterned protective layer is removed.
  • a dry etching or wet etching process such as buffered hydrofluoric acid (BOE) is used to remove the patterned protective layer.
  • BOE buffered hydrofluoric acid
  • FIG. 4 is a top view of FIG. 3.
  • a plurality of holes 302 are arranged in an array, and the holes 302 are elongated.
  • the hole 302 may also be a hole of other shape, and the hole may be rectangular, circular, pentagonal, hexagonal or other polygonal shapes.
  • the width of the defined hole 302 is R1, and the width between two adjacent holes 302 (that is, the width of the pattern 303) is R2.
  • the sizes of R1 and R2 are usually within 10um.
  • R1 and R2 can be equal or different. In this embodiment, R1 and R2 are equal.
  • the substrate 301 is heat-treated so that a plurality of holes 302 (refer to FIG. 4) are combined into a suspended closed cavity 401.
  • the so-called suspension means that the closed cavity 401 is located inside the substrate 301 and is connected to the substrate 301. There is a certain interval on the upper surface.
  • a suspended film 402 is formed above, and a closed cavity 401 is formed inside the substrate 301.
  • the suspended film 402 formed by this heat treatment process is very flat and has a relatively thin thickness, which can be as thin as 1 micron.
  • the closed cavity 401 is located above the center of the substrate 301.
  • the number of closed cavities 401 and the thickness of the suspended film 402 formed under the heat treatment are related to the width R1 of the hole 302 and the width R2 between two adjacent holes 302. In this embodiment Since R1 is equal to R2, all the holes 302 in the substrate 301 are combined into a larger closed cavity 402.
  • the heat treatment is performed in an oxygen-free, low-pressure (lower than atmospheric pressure) environment to prevent the substrate 301 from being oxidized.
  • the oxygen-free environment is a pure hydrogen environment.
  • the oxygen-free environment may also be an inert gas environment.
  • the temperature of the heat treatment is 1100 degrees Celsius.
  • the temperature of the heat treatment may also be higher than 1100 degrees Celsius.
  • the heat treatment is rapid thermal annealing.
  • a lower metal layer (not labeled) is formed on the surface of the substrate 301.
  • the lower metal layer includes a lower electrode 501a and a lower connecting part 501b that are locally connected.
  • the method for forming the lower metal layer 501 includes: forming a metal material layer on the substrate 301; and patterning the metal material layer to obtain a locally connected lower electrode 501a and a lower connecting member 501b.
  • the material of the lower metal layer includes metal materials such as aluminum, molybdenum, palladium, and titanium.
  • the material of the lower metal layer is molybdenum or palladium, because it has good crystal compatibility with the c-axis direction of the piezoelectric thin film layer formed later, and can provide better crystal quality and crystal grain size.
  • the thickness of the lower metal layer is 200-500 nm.
  • a piezoelectric thin film layer 601 is formed on the substrate 301 and the lower metal layer.
  • the material of the piezoelectric film layer 601 is aluminum nitride (AlN) or zinc oxide (ZnO), which grows along the c-axis of the crystal.
  • AlN aluminum nitride
  • ZnO zinc oxide
  • the thickness of the piezoelectric film layer 601 is negatively related to frequency, and its crystal quality is also closely related to the performance of the resonator.
  • the effective coupling coefficient of the piezoelectric film layer 601 is positively correlated with the bandwidth of the resonator.
  • the piezoelectric film layer 601 can be doped with trivalent, divalent, and tetravalent metal elements, such as scandium and calcium-titanium. , Magnesium-titanium, calcium-zirconium, etc.
  • the thickness of the piezoelectric film layer 601 is 0.5 nm-2um.
  • an upper metal layer (not marked) is formed on the piezoelectric film layer 601.
  • the upper metal layer includes a partially connected upper electrode 602a and an upper connecting part 602b.
  • the method for forming the upper metal layer includes: forming a metal material layer on the piezoelectric thin film layer 601; and patterning the metal material layer to obtain a locally connected upper electrode 602a and an upper connecting member 602b.
  • the material of the upper metal layer includes metal materials such as aluminum, molybdenum, palladium, and titanium.
  • the thickness of the upper metal layer is 200-500 nm.
  • the projections of the lower electrode 501a and the upper electrode 602a coincide with the projections of the closed cavity 401, and the projections of the lower connecting part 501b and the upper connecting part 602b are all coincident with
  • the projections of the enclosed cavity 401 are staggered, and the upper connecting part 602b and the lower connecting part 501b are respectively arranged on both sides of the upper electrode 602a and the lower electrode 501a.
  • the piezoelectric film layer 601 is etched to form the opening 701.
  • the opening 701 is in the shape of a ring with a gap (that is, the opening 701 is similar to a C-shape and is not surrounded by 360 degrees), so that the part of the piezoelectric oscillation stack surrounded by the opening 701 is the piezoelectric oscillation stack.
  • the method for forming the opening 701 includes: forming a patterned mask layer covering the piezoelectric thin film layer 601 and the upper metal layer, the patterned mask layer may be photoresist; and the patterned mask layer As a mask, the piezoelectric thin film layer 601 is etched to form an opening 701 in the piezoelectric thin film layer 601; after the opening 701 is formed, the patterned mask layer is removed, and the removal method may be ashing.
  • a contact hole 703 passing through the piezoelectric film layer 601 is formed, and the contact hole 703 exposes the lower connecting member 501b.
  • a lower metal pad 801 and an upper metal pad 802 that are electrically connected to the lower connection part 501b and the upper connection part 602b are formed, respectively.
  • a part of the lower metal pad 801 extends into the contact hole 703 (refer to FIG. 8) and forms an ohmic contact with the lower connection part 501b.
  • the substrate 301 exposed to the opening 701 is etched isotropically, and after etching to the closed cavity 401, continue to etch the lining around the closed cavity 401
  • the bottom 301 is subjected to isotropic etching to form a cavity (also referred to as an isotropic etching cavity) 901 communicating with the opening 701 on the surface of the substrate 301.
  • the piezoelectric oscillating stack is suspended on the cavity 901 and can move in a direction perpendicular to the substrate 301 to deform when subjected to an external force.
  • a protective layer (not shown) is formed at a position other than the opening 701.
  • the protective layer is photoresist. Then, the part of the substrate 301 exposed to the opening 701 is etched to form a groove (not marked) aligned with and communicated with the opening 701 in the substrate 301.
  • the used etchant is used to fill the closed cavity 401, and the substrate 301 around the closed cavity 401 (that is, the cavity wall of the closed cavity 401) is isotropically etched, so that the closed cavity 401 It is rapidly expanded in all directions until the surface layer of the substrate directly above the closed cavity 401 is removed, and a cavity 901 communicating with the opening 701 is formed on the surface of the substrate 301.
  • the isotropic etching is dry etching.
  • the etching gas includes XeF 2 .
  • XeF 2 as an etching gas has very high etching selectivity to silicon, and the etching rate to silicon is relatively fast, which can reach 1 to 3 ⁇ m/min, which can improve the etching efficiency.
  • a closed cavity is formed in the substrate first, and then the substrate exposed to the openings in the piezoelectric oscillatory stack is isotropically etched, and when the etching reaches the closed cavity, continue
  • the isotropic etching of the substrate around the closed cavity not only greatly increases the etching rate and reduces the process cost, but also obtains a larger cavity on the surface of the substrate to facilitate heat dissipation.
  • the surface of the cavity formed by the isotropic etching process is smoother, which serves as an acoustic wave reflection interface with high quality factor and good reliability.
  • the bulk acoustic wave resonator includes a substrate 301, and the surface of the substrate 301 has an isotropic etching cavity (ie, a cavity formed by removing part of the substrate using an isotropic etching process) 901 .
  • the substrate 301 is provided with a piezoelectric oscillating layer (not labeled) having an opening 701, the opening 701 is in communication with the isotropic etching cavity 901, and the piezoelectric oscillating layer is surrounded by the opening 701
  • the part also referred to as a piezoelectric oscillator
  • the isotropic etching cavity 901 is formed by isotropic etching on the inner wall of the closed cavity in the substrate 301, and the closed cavity is formed by combining a plurality of spaced holes after heat treatment. By performing heat treatment on the substrate 301, several holes are combined into a suspended closed cavity.
  • the so-called suspended means that the closed cavity is located inside the substrate 301 and has a certain distance from the upper surface of the substrate 301.
  • the silicon diffusion mechanism on the surface of the substrate is initiated, that is, the holes in the substrate expand in the horizontal direction, so that adjacent holes are merged to form a larger cavity.
  • the energy of the upper surface of the substrate 301 is reduced, causing the upper surface of the substrate 301 to migrate, and the ends of the patterns between the holes can be combined into a whole.
  • a suspended film is formed above the cavity, and a closed cavity is formed inside the substrate 301.
  • the suspended film formed by this heat treatment process is very flat and thin, which can be as thin as 1 micron.
  • the closed cavity is located above the center of the substrate 301.
  • the heat treatment is performed in an oxygen-free, low-pressure (lower than atmospheric pressure) environment to prevent the substrate 301 from being oxidized.
  • the oxygen-free environment is a pure hydrogen environment.
  • the oxygen-free environment may also be an inert gas environment.
  • the temperature of the heat treatment is 1100 degrees Celsius.
  • the temperature of the heat treatment may also be higher than 1100 degrees Celsius.
  • the heat treatment is rapid thermal annealing.
  • an etchant is used to fill the closed cavity, and the substrate 301 around the closed cavity (that is, the cavity wall of the closed cavity 401) is isotropically etched to make the closed cavity
  • the body 401 is rapidly expanded in all directions until the surface layer of the substrate directly above the closed cavity 401 is removed, thereby forming an isotropic etching cavity.
  • the isotropic etching is dry etching.
  • the etching gas includes XeF 2 .
  • the piezoelectric oscillating layer includes a lower metal layer, a piezoelectric thin film layer 601 and an upper metal layer stacked in sequence.
  • the lower metal layer includes a lower electrode 501a and a lower connecting part 501b that are locally connected.
  • the material of the lower metal layer includes metal materials such as aluminum, molybdenum, palladium, and titanium.
  • the material of the lower metal layer is molybdenum or palladium, because it has good crystal compatibility with the c-axis direction of the piezoelectric thin film layer 601, and can provide better crystal quality and crystal grain size.
  • the thickness of the lower metal layer is 200-500 nm.
  • the material of the piezoelectric film layer 601 is aluminum nitride (AlN) or zinc oxide (ZnO), which grows along the c-axis of the crystal.
  • the thickness of the piezoelectric film layer 601 is negatively related to frequency, and its crystal quality is also closely related to the performance of the resonator.
  • the effective coupling coefficient of the piezoelectric film layer 601 is positively correlated with the bandwidth of the resonator.
  • the piezoelectric film layer 601 can be doped with trivalent, divalent, and tetravalent metal elements, such as scandium and calcium-titanium. , Magnesium-titanium, calcium-zirconium, etc.
  • the thickness of the piezoelectric film layer 601 is 0.5 nm-2um.
  • the upper metal layer includes a partially connected upper electrode 602a and an upper connecting part 602b.
  • the material of the upper metal layer includes metal materials such as aluminum, molybdenum, palladium, and titanium.
  • the thickness of the upper metal layer is 200-500 nm.
  • the projections of the lower electrode 501a and the upper electrode 602a coincide with the projections of the isotropic etching cavity 901, and the lower connecting part 501b and the upper connecting part 602b are The projections are all staggered from the projections of the isotropic etching cavity 901, and the upper connecting part 602b and the lower connecting part 501b are respectively arranged on both sides of the upper electrode 602a and the lower electrode 501a.
  • the opening 701 is in the shape of a ring with a gap (that is, the opening 701 is similar to a C-shape and is not surrounded by 360 degrees), so that the part of the piezoelectric oscillation stack surrounded by the opening 701 is the piezoelectric oscillation stack.
  • An upper metal pad 802 and a lower metal pad 801 are formed on the piezoelectric film layer 601.
  • the upper metal pad 802 is located on the upper connecting part 602b and electrically connected to the upper connecting part 602b.
  • the lower metal pad 801 is located on the lower connecting part 501b and electrically connected to the lower connecting part 501b.
  • a part of the lower metal pad 801 extends into a contact hole (not labeled) provided in the piezoelectric film layer 601, and forms an ohmic contact with the lower connection part 501b.
  • a plurality of holes 302 in the substrate 301 are circular, and all the circular holes are arranged in a regular array.
  • a plurality of holes 302 in the substrate 301 are all regular hexagons, and all hexagonal holes are arranged in a regular array. cloth.
  • the width of the hole 302 is defined as R1, and the width between two adjacent holes 302 (that is, the width of the pattern 303 ) Is R2, and the ratio of R2 to R1 is greater than 2.
  • the number of closed cavities 401 formed under the heat treatment is related to the width R1 of the hole 302 and the width R2 between two adjacent holes 302. In this embodiment, since R2 and R1 The ratio is greater than 2. Therefore, in the heat treatment process of the substrate 301 formed with the holes 302, all the holes 302 in the substrate 301 are combined into two or more closed cavities 401 arranged at intervals.
  • the substrate 301 when the substrate 301 is subsequently isotropically etched through the openings in the piezoelectric oscillatory stack, after etching to the closed cavity 401, continue to etch the substrate 301
  • the substrate 301 around the closed cavity 401 (including the part between two adjacent closed cavities 401) is etched isotropically, so that a cavity communicating with the opening can still be formed on the surface of the substrate 301 Body (also called an isotropic etching cavity), the dashed part in FIG. 15 represents the part where the substrate is removed during the isotropic etching process.

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  • 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)
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Abstract

一种体声波谐振器及其制造方法，该方法包括：提供衬底（301）；在所述衬底（301）的表面形成若干间隔排列的孔（302）；进行热处理，使得若干所述孔（302）合并成至少一个悬空的封闭腔体（401）；在所述衬底（301）上形成具有开口（701）的压电震荡堆层；对暴露于所述开口（701）的衬底（301）进行各向同性刻蚀，当刻蚀至所述封闭腔体（401）后继续对所述封闭腔体（401）周围的衬底（301）进行所述各向同性刻蚀，以在所述衬底（301）的表面形成与所述开口（701）连通的腔体（901），至少部分所述压电震荡堆层位于所述腔体（901）之上。该谐振器可以在衬底表面获得更大的腔体，以更有利于散热。

Description

体声波谐振器及其制造方法 技术领域
本发明涉及微电子机械系统(Micro-Electro-Mechanical System，简称MEMS)领域，尤其涉及一种体声波谐振器及其制造方法。
背景技术
近年来，无线通信已成为人们生活的一部分。起初，人们仅能使用手机进行语音通话以及短信的收发。然而，现在智能手机及平板电脑通过第三方软件能支持越来越多的功能，这就需要它们能在多频段下进行各类数据的快速传输。随着4G的成熟和5G的来临，手机支持的频段数量正在迅速上升。根据预测，到2020年，5G应用支持的频段数量将实现翻番，新增50个以上通信频段，全球2G/3G/4G/5G网络合计支持的频段将达到91个以上，手机内的滤波器将增至100多个，全球滤波器市场年需求量将达2千亿只。
射频信号质量取决于手机中的射频滤波器，声波谐振器是射频滤波器和传感器的基本组件。现有射频滤波器主要有三种：介质滤波器、声表面波(SAW)谐振器和薄膜体声波谐振器(FBAR)。介质滤波器是在其表面覆盖作为电壁用的金属层，电磁波被限制在介质内，形成驻波震荡，其主要优点是功率容量大、插入损耗低，但是体积大、难集成。声表面波谐振器是在其压电衬底(如铌酸锂等)的上表面以光刻的手段形成输入和输出叉指电极，利用压电效应激励出声表面波，并检测输出。声表面波谐振器尺寸比介质滤波器小，但其插入损耗大，且受光刻技术的制约工作频率较低、功率容量低、难集成。体声波谐振器在性能上全面超越了介质滤波器和表面波谐振器，其频率由压电层的厚度决定，因此频率可以大大高于表面波谐振器，且体积小、插入损耗低、带外抑制好、功率容量高、易集成。因此，体声波谐振器是近年来的研究热点。
图1是现有一种硅反面刻蚀型体声波谐振器的结构示意图。如图1所示，该体声波谐振器100包括具有反面刻蚀空腔102的硅衬底101、依次堆叠在硅衬底101上的支撑层103、下电极104、压电层105和上电极106。下电极104、压电层105、上电极106构成三明治结构，也叫做压电震荡堆。该谐振器100 采用MEMS体硅微制造工艺从硅片反面刻蚀去除大部分的硅材料，以在压电震荡堆的下表面形成空气交界面，从而将声波限制于压电震荡堆之内，这样可较好的解决散热问题，有效减小声漏，但是其结构稳定性差。
图2是现有另一种空气型体声波谐振器的结构示意图。如图2所示，该谐振器200包括具有空气隙腔202的硅衬底201、依次堆叠在硅衬底201上的支撑层203、下电极204、压电层205和上电极206。下电极204、压电层205、上电极206构成三明治结构，也叫做压电震荡堆。该谐振器200先通过DRIE工艺刻蚀出空气隙腔202，再淀积牺牲层材料(如磷硅玻璃)，接着对牺牲层材料进行化学机械研磨(CMP)，最后再进行释放，露出空气隙腔202，在压电震荡堆的下表面形成空气交界面，从而将声波限制于压电震荡堆之内。此种结构可有效防止声漏、稳定性好，但是散热不畅通，且该工艺涉及牺牲层材料的生长、CMP以及释放，工艺难度高且设备昂贵。
因此，如何获得散热性好的体声波谐振器成为亟待本领域解决的技术问题。
发明内容
本发明所要解决的技术问题是提高体声波谐振器的散热性能。
为了解决上述问题，本发明提供了一种体声波谐振器的制造方法，其包括：提供衬底；在所述衬底的表面形成若干间隔排列的孔；进行热处理，使得若干所述孔合并成至少一个悬空的封闭腔体；在所述衬底上形成具有开口的压电震荡堆层；对暴露于所述开口的衬底进行各向同性刻蚀，当刻蚀至所述封闭腔体后继续对所述封闭腔体周围的衬底进行所述各向同性刻蚀，以在所述衬底的表面形成与所述开口连通的腔体，至少部分所述压电震荡堆层位于所述腔体之上。
可选地，所述热处理为快速热退火。
可选地，所述热处理的温度不小于1100摄氏度。
可选地，经过所述热处理所述若干间隔排列的孔合并为一个所述封闭腔体。
可选地，经过所述热处理所述若干间隔排列的孔合并为两个以上间隔排列的所述封闭腔体。
可选地，所述相邻两个所述孔之间的间隔与孔的宽度之比大于2。
可选地，所述各向同性刻蚀为干法刻蚀。
可选地，在所述衬底上形成具有开口的压电震荡堆层的方法包括：在所述衬底的表面形成依次堆叠的下金属层、压电薄膜层和上金属层，所述下金属层包括局部相连的下电极和下连接部件，所述上金属层包括局部相连的上电极和上连接部件，在垂直于所述衬底的方向上，所述下电极、上电极的投影均与所述封闭腔体的投影重合，所述下连接部件、上连接部件的投影均与所述封闭腔体的投影错开；对所述压电薄膜层进行刻蚀以形成所述开口。
可选地，在形成所述开口的同时，形成穿过所述压电薄膜层的接触孔，所述接触孔露出所述下连接部件；进行所述各向同性刻蚀之前，分别形成与所述下连接部件、上连接部件电连接的下金属焊盘、上金属焊盘。
可选地，所述上连接部件、下连接部件分别布置在所述上电极、下电极的两侧。
可选地，所述开口为具有缺口的环状。
另外，本发明还提供了一种体声波谐振器，其包括：衬底，表面具有各向同性刻蚀腔；位于所述衬底之上的具有开口的压电震荡堆层，所述开口与所述各向同性刻蚀腔连通，至少部分所述压电震荡堆层位于所述各向同性刻蚀腔之上。
可选地，所述各向同性刻蚀腔由对所述衬底内的封闭腔体的内壁进行各向同性刻蚀而成，所述封闭腔体由若干间隔排列的孔经热处理合并而成。
可选地，所述热处理为快速热退火。
可选的，所述各向同性刻蚀为干法刻蚀。
可选地，所述压电震荡堆层包括：依次堆叠的下金属层、压电薄膜层和上金属层；所述下金属层包括局部相连的下电极和下连接部件；所述上金属层包括局部相连的上电极和上连接部件；在垂直于所述衬底的方向上，所述下电极、上电极的投影均与所述各向同性刻蚀腔的投影重合，所述下连接部件、上连接 部件的投影均与所述各向同性刻蚀腔的投影错开；所述开口穿过所述压电薄膜层。
可选地，所述上连接部件、下连接部件分别布置在所述上电极、下电极的两侧。
可选地，还包括：位于所述压电薄膜层之上的上金属焊盘、下金属焊盘；所述上金属焊盘位于所述上连接部件之上，并电连接所述上连接部件；所述下金属焊盘位于所述下连接部件之上，并电连接所述下连接部件。
可选地，所述开口为具有缺口的环状。
本发明先在衬底内形成封闭腔体，再对暴露于压电震荡堆层内的开口的衬底进行各向同性刻蚀，当刻蚀至封闭腔体后，继续对封闭腔体周围的衬底进行各向同性刻蚀，这样不仅可以大为提高刻蚀速率，降低工艺成本，还可以在衬底表面获得更大的腔体，以更有利于散热。进一步的，利用该各向同性刻蚀工艺形成的腔体表面更为光滑，其作为声波反射界面，品质因数高、可靠性好。
附图说明
图1是现有一种硅反面刻蚀型体声波谐振器的结构示意图；
图2是现有另一种空气型体声波谐振器的结构示意图；
图3至图11是本发明的第一实施例中体声波谐振器在不同制造阶段的截面图，其中，图4是图3的俯视图，图11是图10的俯视图；
图12是本发明的第二实施例中体声波谐振器在其中一个制造阶段的俯视图；
图13是本发明的第三实施例中体声波谐振器在其中一个制造阶段的俯视图；
图14至图15是本发明的第四实施例中体声波谐振器在其中两个制造阶段的截面图。
具体实施方式
第一实施例
下面结合附图先对本发明提供的体声波谐振器制造方法的具体实施方式做详细说明。
如图3所示，提供衬底301。在本实施例中，衬底301为单晶硅衬底。当然，在其他实施例中，衬底301也可以选用其他合适的半导体材料。
继续参考图3所示，在衬底301内形成若干间隔排列的孔302，定义相邻两孔302之间的部分为图形303。在本实施例中，孔302的形成方法包括：
在衬底301的表面形成图形化保护层(未图示)，该图形化保护层的制造方法包括：采用低压化学气相沉积、等离子体化学气相沉积或热氧化等工艺在衬底301的上表面形成保护材料层(未图示)之后，然后采用光刻和湿法腐蚀工艺，或者光刻和干法刻蚀工艺去除部分保护材料层，形成具有图形的保护层。该具体实施方式中，保护层的材料为氧化硅，在本发明的其他具体实施方式中，保护层的材料还可以为氮化硅、碳化硅、氮氧化硅等介质材料，可以为单层或多层复合结构。
以所述图形化保护层为掩膜，对衬底301进行刻蚀，以形成若干孔302。该具体实施方式中，采用各向异性刻蚀工艺，例如深反应离子硅刻蚀(DRIE)工艺，刻蚀衬底301得到若干孔302。在本实施例中，孔302的深度为5um～10um。
形成孔302之后，去除该图形化保护层。在具体实施例中，采用干法刻蚀或湿法腐蚀工艺，如用缓冲氢氟酸(BOE)去除该图形化保护层。
图4是图3的俯视图，如图4所示，在本实施例中，若干孔302呈阵列排布，孔302为长条形。当然，在其他实施例中，孔302也可以设置为其他形状的孔，该孔可以是矩形、圆形、五边形、六边形或其他多边形。定义孔302的宽度为R1，相邻两个孔302之间的宽度(即图形303的宽度)为R2，R1、R2的大小通常为10um以内，R1与R2可以相等，也可以不等。在本实施例中，R1和R2相等。
如图5所示，对衬底301进行热处理，使得若干孔302(参考图4)合并成悬空的封闭腔体401，所谓悬空是指封闭腔体401位于衬底301的内部，与衬底301的上表面存在一定的间隔。
结合图4至图5所示，在所述热处理的作用下，引发衬底的表面扩散硅机 制，即，孔302会沿水平方向扩大，使得相邻的孔302之间合并，从而形成更大的腔体。与此同时，在所述热处理的作用下，衬底301的上表面能量降低，使得衬底301的上表面发生迁移，各个图形303的端部得以相互结合为一个整体，从而在该腔体的上方形成悬空薄膜402，在衬底301的内部形成封闭腔体401。通过该热处理工艺形成的悬空薄膜402很平整，且厚度较薄，可以薄至1微米。在具体实施例中，封闭腔体401位于衬底301内部的中心偏上位置。
需说明的是，在所述热处理作用下形成的封闭腔体401的数量、悬空薄膜402的厚度与孔302的宽度R1、相邻两个孔302之间的宽度R2均有关，在本实施例中，由于R1等于R2，故衬底301内的所有孔302合并为一个更大的封闭腔体402。
具体的，所述热处理在不含氧、低压(低于大气压)的环境下进行，以防止衬底301被氧化。在一实施例中，该不含氧的环境为纯氢气环境。当然，在其他实施例中，该不含氧的环境也可以为惰性气体环境。
在本实施例中，所述热处理的温度1100摄氏度。当然，在其他实施例中，所述热处理的温度也可以高于1100摄氏度。进一步的，在本实施例中，所述热处理为快速热退火。
如图6所示，在衬底301的表面形成下金属层(未标识)。所述下金属层包括局部相连的下电极501a和下连接部件501b。在本实施例中，下金属层501的形成方法包括：在衬底301上形成金属材料层；对该金属材料层进行图形化，以获得局部相连的下电极501a和下连接部件501b。在本实施例中，下金属层的材料包括铝、钼、钯、钛等金属材料。优选的，下金属层的材料为钼或钯，因为其与后续形成的压电薄膜层的c轴方向有很好的结晶兼容性，且能提供更好的结晶质量和晶粒尺寸。在本实施例中，下金属层的厚度为200～500nm。
如图7所示，在衬底301和下金属层上形成压电薄膜层601。在本实施例中，压电薄膜层601的材料为氮化铝(AlN)或者氧化锌(ZnO)，其沿晶体的c轴生长。压电薄膜层601的厚度与频率呈负相关，其晶体质量也跟谐振器的性能密切相关。压电薄膜层601的有效耦合系数与谐振器的带宽成正相关，为提高有效耦合系数，可以向压电薄膜层601内掺杂三价、二价、四价金属元素，如钪、钙-钛、镁-钛、钙-锆等。在本实施例中，压电薄膜层601的厚度为 0.5nm～2um。
如图7所示，在压电薄膜层601上形成上金属层(未标识)。所述上金属层包括局部相连的上电极602a和上连接部件602b。在本实施例中，上金属层的形成方法包括：在压电薄膜层601上形成金属材料层；对该金属材料层进行图形化，以获得局部相连的上电极602a和上连接部件602b。在本实施例中，上金属层的材料包括铝、钼、钯、钛等金属材料。在本实施例中，上金属层的厚度为200～500nm。
在垂直于所述衬底301的方向上，所述下电极501a、上电极602a的投影均与所述封闭腔体401的投影重合，所述下连接部件501b、上连接部件602b的投影均与所述封闭腔体401的投影错开，且上连接部件602b、下连接部件501b分别布置在所述上电极602a、下电极501a的两侧。
如图8所示，对所述压电薄膜层601进行刻蚀以形成所述开口701。在本实施例中，开口701呈具有缺口的环状(即开口701类似于C字型，并非呈360度环绕)，使得压电震荡堆层中被开口701环绕的部分为压电震荡堆。
在本实施例中，开口701的形成方法包括：形成覆盖压电薄膜层601和上金属层的图形化掩膜层，该图形化掩膜层可以为光刻胶；以该图形化掩膜层为掩膜，对压电薄膜层601进行刻蚀，以在压电薄膜层601内形成开口701；形成开口701之后，去除该图形化掩膜层，去除方法可以为灰化。
在本实施例中，在形成开口701的同时，形成穿过所述压电薄膜层601的接触孔703，所述接触孔703露出所述下连接部件501b。
如图9所示，分别形成与下连接部件501b、上连接部件602b电连接的下金属焊盘801、上金属焊盘802。其中，下金属焊盘801的一部分伸入接触孔703(参考图8)内，并与下连接部件501b形成欧姆接触。
如图9至图11所示，对暴露于所述开口701的衬底301进行各向同性刻蚀，当刻蚀至所述封闭腔体401后，继续对所述封闭腔体401周围的衬底301进行各向同性刻蚀，以在所述衬底301的表面形成与所述开口701连通的腔体(也称之为各向同性刻蚀腔)901。压电震荡堆悬置于腔体901之上，可以沿着垂直于衬底301的方向运动，以在受到外力的作用时发生形变。
具体地，在进行所述各向同性刻蚀时，在除开口701的位置形成保护层(未 图示)。在具体实施例中，该保护层为光刻胶。然后，对衬底301中暴露于开口701的部分进行刻蚀，以在衬底301内形成与开口701对准并连通的凹槽(未标识)，当刻蚀至该凹槽与下方的封闭腔体401连通时，所采用刻蚀剂充满封闭腔体401，并对封闭腔体401周围的衬底301(即封闭腔体401的腔壁)进行各向同性刻蚀，使得封闭腔体401在各个方向上均被快速扩大，直至封闭腔体401正上方的衬底表层被去除，在衬底301的表面形成与开口701连通的腔体901。
在本实施例中，所述各向同性刻蚀为干法刻蚀。具体地，所述刻蚀气体包括XeF 2。XeF 2作为刻蚀气体对硅具有非常高的刻蚀选择性，对硅的刻蚀速率较快，能够达到1～3μm/min，可以提高刻蚀效率。
在本发明的技术方案中，先在衬底内形成封闭腔体，再对暴露于压电震荡堆层内的开口的衬底进行各向同性刻蚀，当刻蚀至封闭腔体后，继续对封闭腔体周围的衬底进行各向同性刻蚀，这样不仅可以大为提高刻蚀速率，降低工艺成本，还可以在衬底表面获得更大的腔体，以更有利于散热。进一步的，利用该各向同性刻蚀工艺形成的腔体表面更为光滑，其作为声波反射界面，品质因数高、可靠性好。
下面对本实施例的体声波谐振器的结构进行详细介绍。
如图10至图11所示，该体声波谐振器包括衬底301，衬底301的表面具有各向同性刻蚀腔(即利用各向同性刻蚀工艺去除部分衬底所形成的腔)901。所述衬底301之上设置有具有开口701的压电震荡堆层(未标识)，所述开口701与所述各向同性刻蚀腔901连通，所述压电震荡堆层被开口701环绕的部分(也称之为压电震荡堆)位于所述各向同性刻蚀腔901之上，并可以沿着垂直于衬底301的方向运动。
进一步地，各向同性刻蚀腔901由对所述衬底301内的封闭腔体的内壁进行各向同性刻蚀而成，所述封闭腔体由若干间隔排列的孔经热处理合并而成。通过对衬底301进行热处理，使得若干孔合并成悬空的封闭腔体，所谓悬空是指封闭腔体位于衬底301的内部，与衬底301的上表面存在一定的间隔。
在所述热处理的作用下，引发衬底的表面扩散硅机制，即，衬底内的孔会 沿水平方向扩大，使得相邻的孔之间合并，从而形成更大的腔体。与此同时，在所述热处理的作用下，衬底301的上表面能量降低，使得衬底301的上表面发生迁移，各个孔之间的图形的端部得以相互结合为一个整体，从而在该腔体的上方形成悬空薄膜，在衬底301的内部形成封闭腔体。通过该热处理工艺形成的悬空薄膜很平整，且厚度较薄，可以薄至1微米。在具体实施例中，封闭腔体位于衬底301内部的中心偏上位置。
具体的，所述热处理在不含氧、低压(低于大气压)的环境下进行，以防止衬底301被氧化。在一实施例中，该不含氧的环境为纯氢气环境。当然，在其他实施例中，该不含氧的环境也可以为惰性气体环境。
在本实施例中，所述热处理的温度1100摄氏度。当然，在其他实施例中，所述热处理的温度也可以高于1100摄氏度。进一步的，在本实施例中，所述热处理为快速热退火。
在衬底301内形成封闭腔体之后，采用刻蚀剂充满封闭腔体，并对封闭腔体周围的衬底301(即封闭腔体401的腔壁)进行各向同性刻蚀，使得封闭腔体401在各个方向上均被快速扩大，直至封闭腔体401正上方的衬底表层被去除，从而形成各向同性刻蚀腔。
进一步地，所述各向同性刻蚀为干法刻蚀。具体地，所述刻蚀气体包括XeF 2。
所述压电震荡堆层包括依次堆叠的下金属层、压电薄膜层601和上金属层。所述下金属层包括局部相连的下电极501a和下连接部件501b。在本实施例中，下金属层的材料包括铝、钼、钯、钛等金属材料。优选的，下金属层的材料为钼或钯，因为其与压电薄膜层601的c轴方向有很好的结晶兼容性，且能提供更好的结晶质量和晶粒尺寸。在本实施例中，下金属层的厚度为200～500nm。
在本实施例中，压电薄膜层601的材料为氮化铝(AlN)或者氧化锌(ZnO)，其沿晶体的c轴生长。压电薄膜层601的厚度与频率呈负相关，其晶体质量也跟谐振器的性能密切相关。压电薄膜层601的有效耦合系数与谐振器的带宽成正相关，为提高有效耦合系数，可以向压电薄膜层601内掺杂三价、二价、四价金属元素，如钪、钙-钛、镁-钛、钙-锆等。在本实施例中，压电薄膜层601 的厚度为0.5nm～2um。
所述上金属层包括局部相连的上电极602a和上连接部件602b。在本实施例中，上金属层的材料包括铝、钼、钯、钛等金属材料。在本实施例中，上金属层的厚度为200～500nm。
在垂直于所述衬底301的方向上，所述下电极501a、上电极602a的投影均与所述各向同性刻蚀腔901的投影重合，所述下连接部件501b、上连接部件602b的投影均与所述各向同性刻蚀腔901的投影错开，且上连接部件602b、下连接部件501b分别布置在所述上电极602a、下电极501a的两侧。
在本实施例中，开口701呈具有缺口的环状(即开口701类似于C字型，并非呈360度环绕)，使得压电震荡堆层中被开口701环绕的部分为压电震荡堆。
压电薄膜层601之上形成有上金属焊盘802、下金属焊盘801。其中，所述上金属焊盘802位于所述上连接部件602b之上，并电连接所述上连接部件602b。所述下金属焊盘801位于所述下连接部件501b之上，并电连接所述下连接部件501b。下金属焊盘801的一部分伸入设置在压电薄膜层601内的接触孔(未标识)内，并与下连接部件501b形成欧姆接触。
第二实施例
本实施例与第一实施例之间的区别在于：如图12所示，在本实施例中，衬底301内的若干孔302均为圆形，所有圆孔呈规则的阵列排布。
第三实施例
本实施例与第一实施例之间的区别在于：如图13所示，在本实施例中，衬底301内的若干孔302均为正六边形，所有六边形孔呈规则的阵列排布。
第四实施例
本实施例与第一实施例之间的区别在于：如图14所示，在本实施例中，定义孔302的宽度为R1，相邻两个孔302之间的宽度(即图形303的宽度)为R2，R2与R1之比大于2。如前所述，在所述热处理作用下形成的封闭腔体401的数量与孔302的宽度R1、相邻两个孔302之间的宽度R2均有关，在本实施例中，由于R2与R1之比大于2，故，在对形成有孔302的衬底301进行 热处理的工艺下，衬底301内的所有孔302合并为两个以上间隔排列的所述封闭腔体401。
结合图14至图15所示，在后续透过对压电震荡堆层内的开口对衬底301进行各向同性刻蚀时，当刻蚀至所述封闭腔体401后，继续对所述封闭腔体401周围的衬底301(包括相邻两个封闭腔体401之间的部分)进行各向同性刻蚀，这样仍能在所述衬底301的表面形成与所述开口连通的腔体(也称之为各向同性刻蚀腔)，图15中虚线部分表示在该各向同性刻蚀工艺中衬底被去除的部分。
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (19)

  1. 一种体声波谐振器的制造方法，其特征在于，包括：
    提供衬底；
    在所述衬底的表面形成若干间隔排列的孔；
    进行热处理，使得若干所述孔合并成至少一个悬空的封闭腔体；
    在所述衬底上形成具有开口的压电震荡堆层；
    对暴露于所述开口的衬底进行各向同性刻蚀，当刻蚀至所述封闭腔体后继续对所述封闭腔体周围的衬底进行所述各向同性刻蚀，以在所述衬底的表面形成与所述开口连通的腔体，至少部分所述压电震荡堆层位于所述腔体之上。
  2. 根据权利要求1所述的制造方法，其特征在于，所述热处理为快速热退火。
  3. 根据权利要求1所述的制造方法，其特征在于，所述热处理的温度不小于1100摄氏度。
  4. 根据权利要求1所述的制造方法，其特征在于，经过所述热处理所述若干间隔排列的孔合并为一个所述封闭腔体。
  5. 根据权利要求1所述的制造方法，其特征在于，经过所述热处理所述若干间隔排列的孔合并为两个以上间隔排列的所述封闭腔体。
  6. 根据权利要求5所述的制造方法，其特征在于，所述相邻两个所述孔之间的间隔与孔的宽度之比大于2。
  7. 根据权利要求1所述的制造方法，其特征在于，所述各向同性刻蚀为干法刻蚀。
  8. 根据权利要求1至7任一项所述的制造方法，其特征在于，在所述衬底上形成具有开口的压电震荡堆层的方法包括：
    在所述衬底的表面形成依次堆叠的下金属层、压电薄膜层和上金属层，所述下金属层包括局部相连的下电极和下连接部件，所述上金属层包括局部相连的上电极和上连接部件，在垂直于所述衬底的方向上，所述下电极、上电极的投影均与所述封闭腔体的投影重合，所述下连接部件、上连接部件的投影均与所述封闭腔体的投影错开；
    对所述压电薄膜层进行刻蚀以形成所述开口。
  9. 根据权利要求8所述的制造方法，其特征在于，在形成所述开口的同时，形成穿过所述压电薄膜层的接触孔，所述接触孔露出所述下连接部件；
    进行所述各向同性刻蚀之前，分别形成与所述下连接部件、上连接部件电连接的下金属焊盘、上金属焊盘。
  10. 根据权利要求8所述的制造方法，其特征在于，所述上连接部件、下连接部件分别布置在所述上电极、下电极的两侧。
  11. 根据权利要求8所述的制造方法，其特征在于，所述开口为具有缺口的环状。
  12. 一种体声波谐振器，其特征在于，包括：
    衬底，表面具有各向同性刻蚀腔；
    位于所述衬底之上的具有开口的压电震荡堆层，所述开口与所述各向同性刻蚀腔连通，至少部分所述压电震荡堆层位于所述各向同性刻蚀腔之上。
  13. 根据权利要求12所述的体声波谐振器，其特征在于，所述各向同性刻蚀腔由对所述衬底内的封闭腔体的内壁进行各向同性刻蚀而成，所述封闭腔体由若干间隔排列的孔经热处理合并而成。
  14. 根据权利要求13所述的体声波谐振器，其特征在于，所述热处理为快速热退火。
  15. 根据权利要求13所述的体声波谐振器，其特征在于，所述各向同性刻蚀为干法刻蚀。
  16. 根据权利要求12或13所述的体声波谐振器，其特征在于，所述压电震荡堆层包括：
    依次堆叠的下金属层、压电薄膜层和上金属层；
    所述下金属层包括局部相连的下电极和下连接部件；
    所述上金属层包括局部相连的上电极和上连接部件；
    在垂直于所述衬底的方向上，所述下电极、上电极的投影均与所述各向同性刻蚀腔的投影重合，所述下连接部件、上连接部件的投影均与所述各向同性刻蚀腔的投影错开；
    所述开口穿过所述压电薄膜层。
  17. 根据权利要求16所述的体声波谐振器，其特征在于，所述上连接部件、下连接部件分别布置在所述上电极、下电极的两侧。
  18. 根据权利要求16所述的体声波谐振器，其特征在于，还包括：
    位于所述压电薄膜层之上的上金属焊盘、下金属焊盘；
    所述上金属焊盘位于所述上连接部件之上，并电连接所述上连接部件；
    所述下金属焊盘位于所述下连接部件之上，并电连接所述下连接部件。
  19. 根据权利要求12所述的体声波谐振器，其特征在于，所述开口为具有缺口的环状。
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