WO2022061835A1 - 一种体声波谐振器的制造工艺和体声波谐振器 - Google Patents

一种体声波谐振器的制造工艺和体声波谐振器 Download PDF

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WO2022061835A1
WO2022061835A1 PCT/CN2020/118175 CN2020118175W WO2022061835A1 WO 2022061835 A1 WO2022061835 A1 WO 2022061835A1 CN 2020118175 W CN2020118175 W CN 2020118175W WO 2022061835 A1 WO2022061835 A1 WO 2022061835A1
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layer
bottom electrode
electrode layer
modified
substrate
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French (fr)
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李林萍
盛荆浩
江舟
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Hangzhou Xinghe Technology Co Ltd
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Hangzhou Xinghe Technology Co Ltd
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Priority to US18/028,122 priority Critical patent/US12113503B2/en
Priority to EP20954686.0A priority patent/EP4207594A4/en
Priority to KR1020237012102A priority patent/KR20230066418A/ko
Priority to JP2023517369A priority patent/JP7479655B2/ja
Publication of WO2022061835A1 publication Critical patent/WO2022061835A1/zh
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/0211—Means for compensation or elimination of undesirable effects of reflections
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02118—Means for compensation or elimination of undesirable effects of lateral leakage between adjacent resonators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02125—Means for compensation or elimination of undesirable effects of parasitic elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02157—Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; 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
    • H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • H03H9/174—Membranes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; 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
    • H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • H03H9/175—Acoustic mirrors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/021—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the air-gap type
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/023—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the membrane type
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/025—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks comprising an acoustic mirror
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/028—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired values of other parameters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H2009/02165—Tuning
    • H03H2009/02173—Tuning of film bulk acoustic resonators [FBAR]
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials

Definitions

  • the present application relates to the field of communication devices, and mainly relates to a manufacturing process of a bulk acoustic wave resonator and a bulk acoustic wave resonator.
  • the filter is one of the RF front-end modules, which can improve the transmit and receive signals, and is mainly composed of multiple resonators connected by a topological network structure.
  • Baw Bulk Acoustic Wave
  • the filter composed of it has the advantages of small size, strong integration ability, high quality factor Q at high frequency operation, and strong power tolerance. It is the core of the RF front-end. device.
  • the Fbar is a basic structure consisting of upper and lower electrodes and a piezoelectric layer sandwiched between the electrodes.
  • the piezoelectric layer mainly realizes the conversion of electrical energy and mechanical energy.
  • the piezoelectric layer converts electrical energy into mechanical energy, which exists in the form of sound waves.
  • the sound wave has two vibration modes, the transverse wave and the longitudinal wave, and the longitudinal wave is the main mode in the working state of the Fbar.
  • the bottom electrode spans the upper part of the cavity to ensure the mechanical stability of the resonator. When the electrode is connected to other resonators or introduces a signal source, it needs to extend a sufficient length to ensure the normal transmission of electrical signals.
  • the edge extends outside the effective working area.
  • the top electrode and the bottom electrode form an electric field under the external signal source to excite the piezoelectric layer between them to generate mechanical waves and cause parasitic oscillation, which directly affects the frequency response of the resonator, and further causes the waveform instability in the passband of the filter to deteriorate the performance of the device. Therefore, the structural design of the resonator becomes a difficult problem.
  • the resonator structure in the prior art generally suppresses the parasitic oscillation and resonance interference outside the effective area by isolating the interaction of the upper and lower electrodes by the Air gap at the cavity boundary.
  • the Air gap is made by releasing its internal sacrificial layer, and it is necessary to ensure that the piezoelectric layer is
  • the mechanical stability of the top electrode of the suspended part on the top electrode, the top electrode film is stacked on the piezoelectric layer, considering the mechanical stability of the top electrode, especially at high frequency, the thickness of the electrode and the piezoelectric layer becomes very thin (100nm), Stress control and mechanical stability will become very challenging.
  • a staggered electrode structure is used to avoid the parasitic interference problem between the upper and lower electrodes.
  • the staggered and simple electrode structure is attached to the Air gap structure on the substrate.
  • the formation of the above Air gap requires complicated processes, the sides of the cavity are very steep, and the electrodes Growing with piezoelectric layers on steep cavity sides can create severe stress and/or film defects that affect device performance. Or use the mass load at the top to form an abrupt region of acoustic impedance to suppress the shear wave from taking away the energy to increase the Q value, but the piezoelectric layer on the upper part of the cavity edge will replicate the lattice defects and micropores caused by the etching process of the bottom electrode. affect device performance.
  • a groove is formed on the piezoelectric layer to form a sudden change in acoustic impedance to suppress the shear wave from taking away the energy to increase the Q value.
  • the groove is made by etching a depression on the piezoelectric layer. The etching process will cause the bottom of the groove and the The lattice defects and micro-holes of the piezoelectric layer on the sidewall, and even the quality of the piezoelectric layer film around the groove will also be affected to varying degrees. The stress distribution of the originally grown ALN film is destroyed, and the stress change is difficult to control and deteriorate.
  • the performance of the resonator reduces the area of the resonance region in the upper part of the cavity, which increases the size of the filter to a certain extent.
  • the present application proposes a manufacturing process of a bulk acoustic wave resonator and a bulk acoustic wave resonator.
  • a manufacturing process of a bulk acoustic wave resonator comprising:
  • the material of the bottom electrode includes metal and/or alloy material.
  • metal and/or alloy materials eg, Mo
  • the bottom electrode can facilitate chemical processing to generate higher resistance semiconducting or insulating compounds (eg, MoS2 ) .
  • the modified layer is formed by locally chemically treating the peripheral portion of the bottom electrode layer.
  • the abrupt change region of acoustic impedance formed by local chemical treatment the electric field strength in the non-effective working region is weakened and parasitic oscillation is suppressed.
  • the modified layer is formed by chemically treating the entire peripheral portion of the bottom electrode layer.
  • the piezoelectric layer is made to cover at least the modified layer, and an amorphous crystal structure is formed on the modified layer.
  • an amorphous crystal structure By virtue of the amorphous crystal structure, a sudden change in acoustic impedance can be further formed, the loss of acoustic energy and stray signals can be reduced, and the parasitic oscillation can be suppressed.
  • the acoustic mirror includes a cavity or Bragg reflector structure. Different acoustic reflection effects can be obtained according to the choice of different acoustic mirror structures.
  • the chemical treatment includes a vulcanization treatment
  • step S2 specifically includes the following steps:
  • step S23 can also be:
  • the inert gas is used as the carrier, and the sulfur powder is used as the precursor, and the temperature is kept in the range of 600-700° C. to realize the vulcanization reaction.
  • the above two different vulcanization processes can adjust the thickness of the vulcanization layer by controlling different parameters to obtain BAW resonators with different properties.
  • a bulk acoustic wave resonator including a substrate, an acoustic mirror formed on the substrate, and a bottom electrode layer, a piezoelectric layer, and a bottom electrode layer, a piezoelectric layer, and A top electrode layer, wherein a portion of the bottom electrode layer adjacent to the edge of the acoustic mirror is chemically treated to form a modified layer.
  • the modified layer formed by chemical treatment on the bottom electrode layer forms an area of sudden change in acoustic impedance, which can effectively reflect shear waves, weaken the electric field strength outside the effective area, thereby suppressing parasitic oscillation, and improving the performance of the BAW resonator.
  • the piezoelectric layer is fabricated after the modification layer is formed and covers at least the modification layer and forms an amorphous crystalline structure over the modification layer.
  • the amorphous crystal structure abrupt changes in acoustic impedance can be further formed, stray signals can be reduced, and parasitic oscillations can be suppressed.
  • the portion of the bottom electrode layer adjacent to the edge of the acoustic mirror is partially chemically treated to form the modified layer.
  • the portion of the bottom electrode layer adjacent the edge of the acoustic mirror is fully chemically treated to form the modified layer.
  • the surface of the modified layer is slightly higher than the bottom electrode layer that has not been chemically treated. Shear waves can be better reflected with the modified layer slightly higher than the unchemically treated electrode layer.
  • the acoustic mirror includes a cavity or a Bragg reflector. Different acoustic reflection effects can be obtained according to the choice of different acoustic mirror structures.
  • the chemical treatment includes vulcanization treatment
  • the modified layer after vulcanization surrounds the periphery of the bottom electrode layer
  • the material of the bottom electrode includes metal and/or alloy materials.
  • the use of metal and/or alloy materials (eg Mo) for the bottom electrode can facilitate chemical processing to generate higher resistance semiconducting or insulating compounds (eg MoS 2 ); this arrangement enables inactive regions at the edges of the bottom electrode layer A modified layer is formed to achieve abrupt changes in acoustic impedance to suppress parasitic oscillations.
  • a semiconductor or insulator property compound with low conductivity (high resistance) such as MoS 2 is synthesized by chemical means such as vulcanization treatment for the metal properties outside the effective working area, such as the bottom electrode part or the whole end of Mo, so that the adjacent effective
  • the non-effective working area of the working area forms a modified layer of the acoustic impedance abrupt change area, and suppresses the parasitic oscillation outside the effective working area to improve the performance of the device.
  • the modified layer and the piezoelectric layer are lattice mismatched due to the large difference between the crystal plane index and the atomic spacing, and a piezoelectric layer film with amorphous or poor C-axis orientation grows on the interface above the modified layer outside the effective working area.
  • the bulk acoustic wave resonator of this structure weakens or eliminates the electric field strength between the electrodes outside the effective working area, the electrodes cannot stimulate the piezoelectric layer between them to generate mechanical waves, and the parasitic oscillation of the resonator is suppressed, so that the top electrode can be directly drawn from the top of the resonator , which greatly simplifies the wiring of the top electrode.
  • FIG. 1 shows a schematic cross-sectional view of a bulk acoustic wave resonator according to an embodiment of the present invention
  • FIG. 2 shows a schematic cross-sectional view of a bulk acoustic wave resonator according to a specific embodiment of the present invention
  • 3a-c show schematic cross-sectional views of bulk acoustic wave resonators in series and parallel structures according to a specific embodiment of the present invention
  • Figures 4a-k show a flow chart of the fabrication of a bulk acoustic wave resonator according to an embodiment of the present invention.
  • FIG. 1 is a schematic cross-sectional view of a BAW resonator according to an embodiment of the present invention.
  • the BAW resonator includes a substrate 101, an acoustic mirror 102, a bottom electrode 103, a piezoelectric layer 104, The top electrode 105 , the bottom electrode modification layer 106 and the acoustic impedance abrupt change region 107 .
  • the acoustic mirror 102 is formed on the substrate 101, the bottom electrode 103, the piezoelectric layer 104 and the top electrode 105 are sequentially formed on the acoustic mirror 102, wherein the bottom electrode 103, the pressure
  • the position where the electric layer 104 and the acoustic mirror 102 are projected and overlapped in the vertical direction is the effective working area I, and the other areas are the non-working area II.
  • the bottom electrode modification layer 106 is a semiconductor or insulating compound formed by chemical treatment of the bottom electrode 103.
  • the chemical treatment method can be vulcanization treatment.
  • the bottom electrode modification layer 106 may also be formed by other chemical treatment methods, as long as the bottom electrode 103 after the treatment can become a compound with semiconductor or insulating properties. In the following examples, the vulcanization treatment is taken as an example.
  • the material of the bottom electrode 103 includes metal and/or alloy materials, preferably Mo in this embodiment, and the end of the bottom electrode 103 outside the effective working area I is vulcanized to form a bottom electrode modification layer 106, the bottom electrode modified layer 106 is a poor conductor MoS 2 with high resistance, wherein the thickness of the bottom electrode modified layer 106 can be controlled according to the vulcanization process, so that the bottom electrode 103 outside the effective working area I Part or all of Mo is chemically synthesized into MoS 2 , and the thickness of the bottom electrode modification layer 106 can be customized according to the performance requirements of the bulk acoustic wave resonator to achieve the effect of suppressing parasitic oscillation to different degrees, which can be weakened or eliminated to different degrees.
  • the electric field strength obtains different degrees of inhibition effect.
  • the bottom electrode 103 outside the effective working area 1 is partially or completely vulcanized, and the bottom electrode modified layer 106 outside the effective working area 1 forms the reflection shear wave in the abrupt change in acoustic impedance, which can be weakened (when partially modified) or eliminated (when fully modified). ) electric field strength to suppress parasitic oscillation; the bottom electrode modification layer 106 isolates the top electrode 105, the piezoelectric layer 104 and the bottom electrode 103 in the non-effective working area II of the resonator, suppressing the parasitic oscillation between the three-layer structure, thereby Greatly reduces spurious signals and energy loss.
  • the material of the bottom electrode 103 can also be selected from metals such as Cu, Au, Ag, Pt, Ru, etc., which can also achieve the technical effect of the present invention.
  • the vulcanized bottom electrode modification layer 106 forms an acoustic impedance abrupt change region 107, and the shear wave can be reflected back to the effective working region I in the acoustic impedance abrupt change region 107, so as to avoid the reduction of the Q value of the resonator due to energy attenuation .
  • the projection in the vertical direction of the acoustic impedance abrupt change region 107 on the upper part of the substrate 101 at least coincides with the boundary of the acoustic mirror 102 , or a part inside the acoustic mirror 102 and a part in the substrate. This structure is also applicable to the resonator of the SMR-BAW structure.
  • the acoustic mirror 102 shown in FIG. 1 is a cavity structure on the substrate 101, it should be appreciated that the acoustic mirror 102 may also be a Bragg reflection generated by processing on the substrate 101 as shown in FIG. 2 .
  • the layer structure 202 and the Bragg reflection layer structure 202 are formed by stacking film layers with alternating high and low acoustic impedances. The rest of the structure is the same as that shown in FIG.
  • the bulk acoustic wave resonator of the present invention directly chemically synthesizes bad conductors from the bottom electrode 103 outside the effective area I to realize the isolation between electrodes, and the top electrode 105 film is stacked on the On the piezoelectric layer 104 and without considering the mechanical stability of the top electrode, especially at high frequency, the thickness of the electrode and the piezoelectric layer becomes very thin (100nm), which is more controllable for stress control and mechanical stability than the prior art.
  • the top electrode 105 of the bulk acoustic wave resonator of this structure can be directly drawn out from the top of the resonator, which greatly facilitates the wiring of the top electrode 105 .
  • Figures 3a-c show schematic cross-sectional views of BAW resonators in series and parallel structures according to a specific embodiment of the present invention
  • Figure 3a is a BAW resonator with a bottom electrode parallel structure 3a
  • the parallel structure can effectively suppress the parasitic connection between the bottom electrodes, reduce the stray signal and sound energy loss, which is in the It is difficult to achieve in the existing technology.
  • FIG. 3b is a schematic cross-sectional view of the bulk acoustic wave resonator with the top electrodes 305 in parallel.
  • Figure 3c is a schematic cross-sectional view of a bulk acoustic wave resonator with a series structure. The top electrode 305 of the former resonator is connected to the bottom electrode 303 of the latter resonator. It should be noted that the part where the electrodes of the two resonators are connected cannot be modified by the layer 306. isolation, otherwise the high resistance characteristics of the modified layer 306 will greatly attenuate the electrical signal and reduce the Q value of the device.
  • Figures 4a-k show a flow chart of the fabrication of a bulk acoustic wave resonator according to an embodiment of the present invention.
  • the process includes the following processes:
  • a cavity 402 is fabricated on the substrate 401 by a photolithography or etching process.
  • the substrate 401 and the substrate 401 are made of a chemical mechanical polishing process.
  • the sacrificial layer 408 remains horizontal.
  • the material of the substrate 401 can be selected from materials such as Si, SiC, sapphire or spinel, and the material of the sacrificial layer 408 is PSG (P-doped SiO 2 ).
  • the thickness of the sacrificial layer after the chemical mechanical polishing process ie the cavity height after Rlease) is 1-2um.
  • a desired patterned bottom electrode 403 is processed on the substrate 401 and the sacrificial layer 408 , wherein the material of the bottom electrode 403 can be selected from metals such as Mo, Cu, Au, Ag, Pt or Ru.
  • Mo is used as the bottom electrode 403 in this embodiment, and the bottom electrode 403 using Mo can generate MoS 2 with higher resistance during vulcanization.
  • the bottom electrode 403 is subjected to vulcanization treatment.
  • a patterned hard mask 409 is formed on the bottom electrode 403.
  • the material of the hard mask 409 is SiO 2 , and the part of the bottom electrode 403 in the area to be vulcanized is exposed. , as shown in Figure 4d.
  • the process of vulcanizing the bottom electrode 403 includes the following two: placing the wafer with the patterned hard mask in a vapor deposition furnace or a tube furnace, passing H 2 , N The mixed gas of 2 and H 2 S, and the temperature is controlled at about 750 °C (in the range of 700-800 °C), and finally the MoS 2 film can be obtained.
  • the wafer with the patterned hard mask is placed in a vapor deposition furnace or a tube furnace, and O2 is introduced to oxidize the exposed bottom electrode Mo.
  • Inert gas such as Ar gas is used as the carrier, and S powder is used as the precursor, so that the temperature is controlled at about 650 °C (in the range of 600-700 °C), and finally a MoS 2 film can be obtained.
  • a part of the bottom electrode 403 is subjected to vulcanization treatment through the above two processes, so that a part of Mo is combined with S to form the MoS modified layer 406.
  • the gas ratio, The thickness of the final MoS 2 modified layer 406 can be adjusted by parameters such as gas flow rate, temperature, and power. Specifically, appropriate parameters can be adjusted according to the actual required device performance.
  • the vulcanized modified layer 406 is slightly higher than the unvulcanized bottom electrode 403, and the height difference between the modified layer 406 and the bottom electrode 403 is in the range of 0-100 nm, which is a height difference formed.
  • FIG. 4e shows a modified layer 406 with a certain thickness formed by partial vulcanization of the exposed bottom electrode 403.
  • the thickness can be adjusted according to the above process.
  • the abrupt change in acoustic impedance of the modified layer 406 can reflect shear waves.
  • Modified layers with different thicknesses 406 can weaken the electric field strength to different degrees and suppress parasitic oscillation;
  • Fig. 4f shows the modified layer 406 formed by vulcanizing the bare bottom electrode 403, the abrupt change in acoustic impedance of the modified layer 406 can reflect the shear wave, and the modification of the complete vulcanization treatment Layer 406 can cancel out the electric field strength and suppress parasitic oscillations.
  • the hard mask 409 is removed. Specifically, the hard mask 409 can be removed by using a hydrofluoric acid etchant. As shown in the top view in FIG. 4h , at least one side of the bottom electrode 403 is vulcanized, which is projected inside the cavity 402 or coincides with the boundary of the cavity 402 .
  • the vulcanized modified layer 406 surrounds the end of the bottom electrode 403 to form a region with abrupt changes in acoustic impedance to reflect shear waves, weaken or eliminate the electric field strength outside the effective region and suppress parasitic oscillations.
  • the piezoelectric layer 404 is continued to be fabricated on the above basis, wherein the piezoelectric layer 404 may be an ALN thin film.
  • the MoS 2 of the modified layer 406 and the ALN of the piezoelectric layer 404 are lattice mismatched due to the large difference between the crystal plane index and the atomic spacing, so that the MoS 2 interface outside the effective working area has poor C-axis orientation and even amorphous.
  • the top electrode 405 is continuously fabricated and patterned on the piezoelectric layer 404 and the amorphous AlN film 409.
  • the AlN film 409 with poor C-axis orientation and even the amorphous AlN film 409 is difficult to be affected by the top electrode 405 and the top electrode 405 on its upper surface.
  • the bottom electrode 403 on the lower surface excites the piezoelectric layer 404 therebetween to generate mechanical waves, which can further form abrupt changes in acoustic impedance, reduce acoustic energy loss and stray signals, and greatly suppress parasitic oscillations.
  • hydrofluoric acid etchant to release the sacrificial layer 408 to obtain the cavity 402 (as shown in FIG. 4k )
  • the manufacturing process of the bulk acoustic wave resonator is completed.
  • the modified layer 406 is formed in the non-working area at the edge of the bottom electrode 403 by the above-mentioned process to realize the sudden change of acoustic impedance and suppress the parasitic oscillation.
  • the thickness of the modified layer 406 can also be adjusted according to different device performance requirements to achieve attenuation Or eliminate the electric field strength to suppress parasitic oscillations.
  • a sudden change in acoustic impedance can be further formed, reducing the loss of acoustic energy and spurious signals, suppress spurious oscillations.
  • the above process method can be used not only for the manufacture of bulk acoustic wave resonators, but also for wireless communication equipment (2G, 3G, 4G, 5G mobile phones, Wi-Fi, Pad, smart watch, IOT, car or GPS and other terminal scenarios) , BAW filter of any structure and mode used in radio frequency, etc., including Fbar, SMR-BAW, CRF, SCF, SBAR, RBAR or DBAR, etc. It is also applicable to all device types such as SAW resonators, piezoelectric devices or sensors made of any piezoelectric material including ZnO, PZT, and any piezoelectric material such as lithium carbonate LN or lithium niobate LT.

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  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
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Abstract

公开了一种体声波谐振器的制造工艺，包括在衬底上制作声反射镜，在衬底上制作用于覆盖声反射镜的底电极层；对底电极层的外围部分进行化学处理以形成改性层，改性层环绕底电极层；在底电极层上制作压电层；在压电层上制作顶电极层。还公开了一种体声波谐振器，包括衬底、形成在衬底上的声反射镜以及依次形成具有声反射镜的衬底上的底电极层、压电层和顶电极层，其中底电极层的临近声反射镜的边缘的部分被化学处理以形成改性层。凭借改性层的形成削弱或消除了有效工作区域外电极之间的电场强度，电极无法激励其间的压电层产生机械波而抑制了谐振器寄生振荡，同时大大简化了顶电极的布线。

Description

一种体声波谐振器的制造工艺和体声波谐振器 技术领域
本申请涉及通信器件领域，主要涉及一种体声波谐振器的制造工艺和体声波谐振器。
背景技术
随着电磁频谱的日益拥挤、无线通讯设备的频段与功能增多，无线通讯使用的电磁频谱从500MHz到5GHz以上高速增长，因此对性能高、成本低、功耗低、体积小的射频前端模块需求也日益增长。滤波器是射频前端模块之一，可改善发射和接收信号，主要由多个谐振器通过拓扑网络结构连接而成。Baw(Bulk Acoustic Wave)是一种体声波谐振器，由它组成的滤波器具有体积小、集成能力强、高频工作时保证高品质因素Q、功率承受能力强等优势而作为射频前端的核心器件。
Fbar是由上下电极和夹在电极之间的压电层组成的基本结构。压电层主要实现电能与机械能的转化。当Fbar的上下电极施加电场时，压电层将电能转换为机械能，机械能以声波的形式存在。声波有横波和纵波两种振动模式，纵波是Fbar工作状态下的主要模式。底电极横跨在空腔上部以保证谐振器的机械稳定性，电极连接其它谐振器或引入信号源时需向外延足够的长度以保证电信号正常传输，此时沿伸在有效工作区域外的顶电极与底电极在外接信号源下形成电场激励其间的压电层产生机械波引发寄生振荡，直接影响谐振器的频率响应，进一步造成滤波器通带内的波形不稳等恶化器件性能的情况，因此谐振器的结构设计成为一个难题。
现有技术中的谐振器结构一般通过空腔边界的Air gap隔离上下电极的相互作用而抑制有效区域外的寄生振荡和谐振干涉，Air gap通过释放其内部牺牲层制成，需要保证压电层上的悬空部分的顶电极的机械稳定性，顶电极薄膜堆积在压电层上，考虑到顶电极机械稳定性， 尤其是在高频段时，电极和压电层厚度变得非常薄(100nm)，应力控制和机械稳定性将会变得非常具有挑战性。或者使用了交错的电极结构避免上下电极之间的寄生干涉问题，交错简单的电极结构依附于衬底上的Air gap结构，形成上述Air gap需要复杂的工艺，空腔侧边非常的陡峭，电极与压电层在陡峭的空腔侧边生长会产生严重的应力和/或薄膜缺陷而影响器件性能。或者使用顶部的质量负载形成声阻抗突变区域而抑制横波带走能量提升Q值，但空腔边缘上部的压电层会复制其底电极经刻蚀工艺所带来的晶格缺陷及微孔而影响器件性能。又或者通过在压电层上制作凹槽形成声阻抗突变区域而抑制横波带走能量提升Q值，凹槽通过在压电层上蚀刻一个凹陷口制成，刻蚀工艺会造成凹槽底部及侧壁的的压电层的晶格缺陷及微孔洞，甚至凹槽周围的压电层薄膜质量同样会受不同程度的影响，原始生长的ALN薄膜应力分布被破坏，应力变化难以控制，恶化谐振器性能，另一方面减小空腔上部的谐振区域面积，一定程度增加了滤波器的尺寸。还存在部分其他交错的电极结构，虽然避免了上下电极之间的寄生干涉，但容易造成能量泄露，进而使其Q值非常低。
发明内容
针对现有技术中的以上技术问题，本申请提出了一种体声波谐振器的制造工艺和体声波谐振器。
根据本发明的一方面，提出了一种体声波谐振器的制造工艺，包括：
S1、在衬底上制作声反射镜，
S2、在衬底上制作用于覆盖声反射镜的底电极层；
S3、对底电极层的外围部分进行化学处理以形成改性层，改性层环绕底电极层；
S4、在底电极层上制作压电层；以及
S5、在压电层上制作顶电极层。
在具体的实施例中，底电极的材质包括金属和/或合金材料。采用金属和/或合金材料(例如Mo)制作底电极能够便于进行化学处理以 生成电阻较高的半导体或绝缘性质的化合物(例如MoS 2)。
在具体的实施例中，改性层是对底电极层的外围部分进行局部化学处理形成的。凭借局部化学处理形成的声阻抗突变区域，削弱了在非有效工作区域的电场强度而抑制寄生振荡。
在具体的实施例中，改性层是对底电极层的外围部分进行全部化学处理形成的。凭借全部化学处理形成的声阻抗突变区域，消除了在非有效工作区域的电场强度而抑制寄生振荡。
在具体的实施例中，在步骤S4中使得压电层至少覆盖改性层，并在改性层上方形成无定形态的晶体结构。凭借该无定形态的晶体结构可以进一步形成声阻抗突变，减少声能损耗和杂散信号，抑制寄生振荡。
在具体的实施例中，声反射镜包括空腔或布拉格反射层结构。根据不同的声反射镜结构的选择可以获得不同的声反射效果。
在具体的实施例中，化学处理包括硫化处理，且步骤S2具体包括以下步骤：
S21、在底电极层上制作图形化的硬质掩膜，使得待硫化区域的底电极暴露；
S22、将带有硬质掩膜的晶圆放入反应炉中，通入由氧气、氮气和硫化氢组成的混合气体，并且将温度保持在700-800℃范围内以实现硫化反应；以及
S23、去除硬质掩膜。凭借该步骤可以对底电极层上的特定区域进行硫化处理以形成声阻抗突变的改性层。
在具体的实施例中，步骤S23还可以为：
将带有硬质掩膜的晶圆放入反应炉中，通入氧气以实现氧化；
利用惰性气体作为载体，并且以硫粉作为前驱体，并且保持温度在600-700℃范围内，以实现硫化反应。上述两种不同的硫化工艺可以通过控制不同的参数调节硫化层的厚度以获得不同性能的体声波谐振器。
根据本发明的第二方面，提出了一种体声波谐振器，包括衬底、形成在衬底上的声反射镜以及依次形成具有声反射镜的衬底上的底电极层、压电层和顶电极层，其中底电极层的临近声反射镜的边缘的部分被实施化学处理以形成改性层。凭借对底电极层上的化学处理形成的改性层形成声阻抗突变区域，可以有效地反射横波，削弱有效区域外电场强度进而抑制寄生振荡，提升体声波谐振器的性能。
在具体的实施例中，压电层在改性层形成后被制作并且至少覆盖改性层，并在改性层上方形成无定形态的晶体结构。凭借该无定形态的晶体结构可以进一步形成声阻抗突变，减少杂散信号，抑制寄生振荡。
在具体的实施例中，底电极层的临近声反射镜的边缘的部分被部分化学处理以形成改性层。凭借局部化学处理形成的声阻抗突变区域，削弱了在非有效工作区域的电场强度而抑制寄生振荡。
在具体的实施例中，底电极层的临近声反射镜的边缘的部分被完全化学处理以形成改性层。凭借全部化学处理形成的声阻抗突变区域，消除了在非有效工作区域的电场强度而抑制寄生振荡。
在具体的实施例中，改性层的表面稍微高于未被化学处理的底电极层。凭借稍高于未化学处理的电极层的改性层能够更好地反射横波。
在具体的实施例中，声反射镜包括空腔或布拉格反射层。根据不同的声反射镜结构的选择可以获得不同的声反射效果。
在具体的实施例中，化学处理包括硫化处理，硫化后的改性层环绕底电极层的外围，底电极的材质包括金属和/或合金材料。采用金属和/或合金材料(例如Mo)制作底电极能够便于进行化学处理以生成电阻较高的半导体或绝缘性质的化合物(例如MoS 2)；凭借该设置能够在底电极层边缘的非工作区域形成改性层以实现声阻抗突变进而抑制寄生振荡。
本发明通过对有效工作区域外的金属性质如Mo的底电极部分或全部末端通过硫化处理等化学手段合成一种电导率较低(电阻高)的 半导体或绝缘体性质化合物如MoS 2，使得紧邻有效工作区域的非有效工作区域形成声阻抗突变区域的改性层，并抑制有效工作区域外的寄生振荡而提升器件性能。该改性层与压电层因晶面指数与原子间距差异大而晶格失配，在有效工作区域外的改性层上方界面上生长出无定形态或C轴取向性差的压电层薄膜，从而进一步抑制了有效工作区域外的寄生振荡。该结构的体声波谐振器削弱或消除了有效工作区域外电极之间的电场强度，电极无法激励其间的压电层产生机械波而抑制了谐振器寄生振荡，使顶电极可以直接从谐振器顶部引出，大大简化了顶电极的布线。
附图说明
包括附图以提供对实施例的进一步理解并且附图被并入本说明书中并且构成本说明书的一部分。附图图示了实施例并且与描述一起用于解释本发明的原理。将容易认识到其它实施例和实施例的很多预期优点，因为通过引用以下详细描述，它们变得被更好地理解。附图的元件不一定是相互按照比例的。同样的附图标记指代对应的类似部件。
图1示出了根据本发明的一个实施例的体声波谐振器的剖面示意图；
图2示出了根据本发明的一个具体的实施例的体声波谐振器的剖面示意图；
图3a-c示出了根据本发明的一个具体的实施例的串联和并联结构下的体声波谐振器的剖面示意图；
图4a-k示出了根据本发明的一个实施例的体声波谐振器的制作流程图。
具体实施方式
下面结合附图和实施例对本申请作进一步的详细说明。可以理解的是，此处所描述的具体实施例仅仅用于解释相关发明，而非对该发明的限定。另外还需要说明的是，为了便于描述，附图中仅示出了与有关发明相关的部分。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。下面将参考附图并结合实施例来详细说明本申请。
图1出了根据本发明的一个实施例的体声波谐振器的剖面示意图，如图1所示，该体声波谐振器包括衬底101、声反射镜102、底电极103、压电层104、顶电极105、底电极改性层106和声阻抗突变区域107。声反射镜102在衬底101上形成，底电极103、压电层104和顶电极105依次在声反射镜102上形成，其中，该体声波谐振器中未作化学处理的底电极103、压电层104与声反射镜102在垂直方向上投影重合的位置为有效工作区域I，其他区域为非工作区域Ⅱ。底电极改性层106为底电极103经过化学处理形成的半导体或绝缘性质的化合物，优选的，化学处理的方式可以采用硫化处理。应当认识到，还可以采用其他的化学处理的方式形成底电极改性层106，只需满足处理后的底电极103能够成为半导体或绝缘性质的化合物即可。后续实施例中均以硫化处理为例。
在具体的实施例中，底电极103的材料包括金属和/或合金材料，在本实施例中优选的为Mo，有效工作区域I外的底电极103末端被硫化处理以形成底电极改性层106，底电极改性层106为电阻较高的不良导体MoS 2，其中，底电极改性层106的厚度可以根据硫化处理的工艺进行控制，以使得有效工作区域I外的底电极103末端的部分或全部Mo化学合成MoS 2，可以根据体声波谐振器的性能要求进行定制化的底电极改性层106的厚度设置以实现不同程度的抑制寄生振荡的效果，可以实现不同程度地削弱或者消除电场强度获得不同程度的抑制效果。使有效工作区域I外的底电极103部分或全部硫化，有效工作区域I外的底电极改性层106形成声阻抗突变区反射横波，可以削弱(局部改性时)或消除(全部改性时)电场强度而抑制寄生振荡；底电极改性层106在谐振器的非有效工作区域Ⅱ隔绝了顶电极105、压电层104与底电极103，抑制了三层结构之间产生寄生振荡，从而大大减少了杂散信号和能量损耗。应当认识到，底电极103的材料除了选用Mo之外，还可以选用Cu、Au、Ag、Pt、Ru等金属，同样能够 实现本发明的技术效果。
在具体的实施例中，经硫化处理的底电极改性层106形成声阻抗突变区域107，横波可以在声阻抗突变区域107反射回有效工作区域I，避免了因能量衰减而降低谐振器Q值。衬底101上部的声阻抗突变区域107在垂直方向上的投影至少与声反射镜102的边界重合，或一部分于声反射镜102内部一部分于衬底。此结构同样适用于SMR-BAW结构的谐振器。
虽然图1中示出的声反射镜102为衬底101上的空腔结构，但应当认识到，声反射镜102还可以为如图2中所示的在衬底101上加工生成的布拉格反射层结构202，布拉格反射层结构202由高低声阻抗交替的膜层堆叠而成，其余结构与图1一致，此处不再赘述，同样能够实现本发明的技术效果。
本发明的体声波谐振器与现有技术中的体声波谐振器的结构相比，直接将有效区域I外的底电极103化学合成不良导体来实现电极之间的隔离，顶电极105薄膜堆积在压电层104上并且无需考虑顶电极机械稳定性，尤其是在高频段时，电极和压电层厚度变得非常薄(100nm)，对于应力控制和机械稳定性的控制相比现有技术更加容易；还解决了寄生干涉问题时受应力和/或薄膜缺陷的影响；并且相较于现有技术不会破坏压电层薄膜质量，也不会影响器件尺寸。此外，该结构的体声波谐振器的顶电极105可以直接从谐振器顶部引出，极大便利了顶电极105的布线。
继续参考图3a-c，图3a-c示出了根据本发明的一个具体的实施例的串联和并联结构下的体声波谐振器的剖面示意图，图3a为底电极并联结构的体声波谐振器的剖面示意图，如图3a所示，在两谐振器通过底电极303并联时，连接处的改性层306投影覆盖相互并联的谐振器之间的衬底301上，并且改性层306投影落入于两空腔302内部或与两空腔302边界重合，相比现有技术，该并联结构可以有效的抑制底电极之间连接时的寄生，减少杂散信号与声能损耗，这是在现有技术中很难实现的。图3b为顶电极305并联结构的体声波谐振器的剖面示意图，如图3b所示，两谐振器在通过顶电极305并联时，因为压电层 304和两底电极303之间被改性层306隔离，此时也可以抑制寄生损耗，提高谐振器性能。图3c为串联结构的体声波谐振器的剖面示意图，前一谐振器的顶电极305与后一谐振器的底电极303连接，应当注意的是两谐振器电极相连的部位不可被改性层306隔离，否则改性层306的高电阻特性会使电信号大大衰减而降低器件Q值。
图4a-k示出了根据本发明的一个实施例的体声波谐振器的制作流程图。该工艺包括以下流程：
首先如图4a和4b所示，在衬底401上通过光刻或蚀刻的工艺制作空腔402，利用PVD工艺在空腔402中生长牺牲层408后，通过化学机械抛光工艺使衬底401和牺牲层408保持水平。其中，衬底401的材料可以选择Si、SiC、蓝宝石或尖晶石等材质，牺牲层408的材质为PSG(掺P的SiO 2)。优选的，经化学机械抛光工艺后牺牲层厚度(即Rlease后空腔高度)为1-2um。
如图4c所示，在衬底401和牺牲层408上加工所需图形化的底电极403，其中，底电极403的材质可选用Mo、Cu、Au、Ag、Pt或Ru等金属。优选的，本实施例中采用Mo作为底电极403，采用Mo的底电极403能够在硫化处理时生成具有更高电阻的MoS 2。然后对底电极403进行硫化处理，具体的，在底电极403上制作图形化的硬质掩膜409，该硬质掩膜409的材质为SiO 2，露出待硫化处理区域的底电极403的部分，如图4d。
在具体的实施例中，对底电极403进行硫化处理的工艺包括以下两种：将带有图形化硬掩模的晶圆放置在在气相沉积炉或管式炉中，通入H 2、N 2与H 2S的混合气体，将温度控制在750℃左右(700-800℃范围内)，最终可获得MoS 2薄膜。或者将带有图形化硬掩模的晶圆放置在在气相沉积炉或管式炉中，通入O 2将裸露的底电极Mo氧化。再以Ar气等惰性气体作载体，以S粉作前驱体，使温度控制在650℃左右(600-700℃范围内)，最终可获得MoS 2薄膜。
在具体的实施例中，通过上述两种工艺对底电极403中的部分的区域进行硫化处理使得一部分Mo与S结合成为MoS 2改性层406，优选的，可以通过对工艺中的气体比例、气体流量、温度、功率等参数 来调节最终MoS 2改性层406的厚度，具体可以根据实际所需的器件性能来调节适当的参数。硫化后的改性层406稍微高于未被硫化的底电极403，改性层406与底电极403的高度差在0-100nm范围内，形成的高度差。图4e为将裸露的底电极403局部硫化处理生成一定厚度的改性层406，该厚度可以根据上述的工艺进行调节，改性层406的声阻抗突变特性可以反射横波，不同厚度的改性层406可以不同程度地削弱电场强度而抑制寄生振荡；图4f为将裸露的底电极403全部硫化处理生成改性层406，改性层406的声阻抗突变特性可以反射横波，完全硫化处理的改性层406可以消除电场强度而抑制寄生振荡。
继续参考图4g，将硬质掩膜409去除，具体可以利用氢氟酸蚀刻剂进行硬质掩膜409的去除。如图4h中的俯视图中所示，底电极403至少有一侧硫化处理，投影于空腔402内部或与空腔402边界重合。硫化后的改性层406环绕底电极403末端，形成声阻抗突变区域反射横波，削弱或消除有效区域外电场强度而抑制寄生振荡。
如图4i，在上述基础上继续制作压电层404，其中，压电层404可以为ALN薄膜。改性层406的MoS 2与压电层404的ALN因晶面指数与原子间距差异大而晶格失配，使得有效工作区域外的MoS 2界面上生长出C轴取向性差甚至无定形态的AlN薄膜409。如图4j继续在压电层404以及无定形态的AlN薄膜409上制作顶电极405并图形化处理，C轴取向性差甚至无定形态的AlN薄膜409因难以被其上表面的顶电极405和下表面的底电极403激励其间的压电层404产生机械波，可以进一步形成声阻抗突变，减少声能损耗和杂散信号，大大抑制寄生振荡。最后利用氢氟酸蚀刻剂释放牺牲层408获得空腔402(如图4k)，完成体声波谐振器的制造工艺。
利用上述工艺在底电极403边缘的非工作区域通过硫化处理工艺形成改性层406以实现声阻抗突变和抑制寄生振荡，还可以根据不同的器件性能要求调整改性层406的厚度，以实现减弱或消除电场强度进而抑制寄生振荡。另外在改性层406上方，通过改性层406的MoS 2与压电层404的ALN因晶格失配而形成的无定形态的晶体结构，可以进一步形成声阻抗突变，减少声能损耗和杂散信号，抑制寄生振荡。
上述工艺方法不仅可以用于体声波谐振器的制造，同样还适用于无线通讯设备(2G、3G、4G、5G的手机、Wi-Fi、Pad、智能手表、IOT、汽车或GPS等终端场景)、射频等使用的任何结构和方式的BAW滤波器，包括Fbar、SMR-BAW、CRF、SCF、SBAR、RBAR或DBAR等。也适用于任何压电材料包括ZnO，PZT以及碳酸锂LN或铌酸锂LT等任何压电材料制成的SAW谐振器、压电器件或传感器等mems类的所有器件类型。
以上描述了本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。
在本申请的描述中，需要理解的是，术语“上”、“下”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。措词‘包括’并不排除在权利要求未列出的元件或步骤的存在。元件前面的措词‘一’或‘一个’并不排除多个这样的元件的存在。在相互不同从属权利要求中记载某些措施的简单事实不表明这些措施的组合不能被用于改进。在权利要求中的任何参考符号不应当被解释为限制范围。

Claims (15)

  1. 一种体声波谐振器的制造工艺，包括以下步骤：
    S1、在衬底上制作声反射镜，
    S2、在衬底上制作用于覆盖所述声反射镜的底电极层；
    S3、对所述底电极层的外围部分进行化学处理以形成改性层，所述改性层环绕所述底电极层；
    S4、在所述底电极层上制作压电层；以及
    S5、在所述压电层上制作顶电极层。
  2. 根据权利要求1所述的制造工艺，其中，所述底电极的材质包括金属和/或合金材料。
  3. 根据权利要求1所述的制造工艺，其中，所述改性层是对所述底电极层的外围部分进行局部化学处理形成的。
  4. 根据权利要求1所述的制造工艺，其中，所述改性层是对所述底电极层的外围部分进行全部化学处理形成的。
  5. 根据权利要求1所述的制造工艺，其中，在所述步骤S4中使得所述压电层至少覆盖所述改性层，并在所述改性层上方形成无定形态的晶体结构。
  6. 根据权利要求1所述的制造工艺，其中，所述声反射镜包括空腔或布拉格反射层结构。
  7. 根据权利要求1-6中任一项所述的制造工艺，其中，所述化学处理包括硫化处理，且所述步骤S2具体包括以下步骤：
    S21、在所述底电极层上制作图形化的硬质掩膜，使得待硫化区域的底电极暴露；
    S22、将带有所述硬质掩膜的晶圆放入反应炉中，通入由氧气、氮气和硫化氢组成的混合气体，并且将所述温度保持在700-800℃范围内以实现硫化反应；以及
    S23、去除所述硬质掩膜。
  8. 根据权利要求7所述的制造工艺，其中，所述步骤S22还可以 为：
    将带有所述硬质掩膜的晶圆放入反应炉中，通入氧气以实现氧化；利用惰性气体作为载体，并且以硫粉作为前驱体，并且保持温度在600-700℃范围内，以实现硫化反应。
  9. 一种体声波谐振器，包括衬底、形成在衬底上的声反射镜以及依次形成具有所述声反射镜的衬底上的底电极层、压电层和顶电极层，其中所述底电极层的临近所述声反射镜的边缘的部分被实施化学处理以形成改性层。
  10. 根据权利要求9所述的体声波谐振器，其中，所述压电层在所述改性层形成后被制作并且至少覆盖所述改性层，并在所述改性层上方形成无定形态的晶体结构。
  11. 根据权利要求9所述的体声波谐振器，其中，所述底电极层的临近所述声反射镜的边缘的部分被部分化学处理以形成所述改性层。
  12. 根据权利要求9所述的体声波谐振器，其中，所述底电极层的临近所述声反射镜的边缘的部分被完全化学处理以形成所述改性层。
  13. 根据权利要求9所述的体声波谐振器，其中，所述改性层的表面高于未被化学处理的所述底电极层。
  14. 根据权利要求9所述的体声波谐振器，其中，所述声反射镜包括空腔或布拉格反射层结构。
  15. 根据权利要求9-14中任一项所述的体声波谐振器，其中，所述化学处理包括硫化处理，硫化后的所述改性层环绕所述底电极层的外围，所述底电极层的材质包括金属和/或合金材料。
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US12113503B2 (en) 2024-10-08
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US20230327627A1 (en) 2023-10-12

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