WO2020146973A1 - 声表面波滤波器及其制备方法、射频前端芯片和移动终端 - Google Patents
声表面波滤波器及其制备方法、射频前端芯片和移动终端 Download PDFInfo
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- WO2020146973A1 WO2020146973A1 PCT/CN2019/071588 CN2019071588W WO2020146973A1 WO 2020146973 A1 WO2020146973 A1 WO 2020146973A1 CN 2019071588 W CN2019071588 W CN 2019071588W WO 2020146973 A1 WO2020146973 A1 WO 2020146973A1
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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
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
Definitions
- This application relates to the technical field of semiconductor equipment, in particular to a surface acoustic wave filter and a manufacturing method thereof, and also to a radio frequency front-end chip and a mobile terminal containing the surface acoustic wave filter.
- filters smaller than 6 GHz generally use surface acoustic wave (Surface Acoustic Wave, SAW) or bulk acoustic wave (Body Acoustic Wave, BAW) technology.
- SAW Surface Acoustic Wave
- BAW Body Acoustic Wave
- the SAW filter compared to the BAW filter, the SAW filter has the advantages of relatively simple technology and relatively low cost, and is widely used in the frequency band less than 2 GHz.
- the traditional SAW filter structure is to directly form an Interdigital Transducer (IDT) on the substrate.
- IDT Interdigital Transducer
- the SAW filter structure will cause acoustic energy to leak from the substrate, resulting in low quality factor (Q) and insertion loss (IL) of the SAW filter.
- the present application provides a surface acoustic wave filter and a manufacturing method thereof.
- this application also provides a radio frequency front-end chip and a mobile terminal including the surface acoustic wave filter.
- the first aspect of the present application provides a surface acoustic wave filter, including: a substrate and a piezoelectric material layer disposed oppositely, a cavity is provided between the substrate and the piezoelectric material layer; A bonding pad for bonding the substrate and the piezoelectric material layer is arranged on the side wall; an interdigital transducer is arranged on the surface of the piezoelectric material layer facing the substrate; the interdigital transducer Located in the cavity.
- the surface acoustic wave filter provided by the first aspect includes a substrate and a piezoelectric material layer disposed oppositely, wherein a cavity is provided between the substrate and the piezoelectric material layer; the piezoelectric material layer is provided with an interdigital switch on the surface facing the substrate Energy device; the interdigital transducer is located in the cavity.
- the inside of the cavity can be a vacuum environment or a gas environment. Acoustic waves cannot propagate in vacuum, and compared to solid media, the ability of acoustic waves to propagate in gaseous media is lower. Therefore, the energy of sound waves is not easy to leak out from the substrate through the cavity, so it is formed on the substrate and the piezoelectric material layer.
- the cavity in between can reduce the existence of stray mode sound waves and reduce the possibility of sound wave energy leakage from the substrate, thereby increasing the Q value and insertion loss of the SAW filter.
- the solder pad includes a first solder pad located on the surface of the substrate facing the piezoelectric material layer, and/or, located on the surface of the piezoelectric material layer facing the substrate.
- the second solder pad; the first solder pad and the second solder pad are stacked. This possible implementation is more convenient for bonding the substrate and the piezoelectric material layer.
- the filter further includes a temperature compensation layer, the temperature compensation layer being located on a surface of the piezoelectric material layer facing away from the substrate.
- the filter further includes: a sound velocity increasing layer, the sound velocity increasing layer at least covers a surface area of the temperature compensation layer facing away from the interdigital transducer.
- the sound velocity increasing layer can increase the equivalent sound velocity of the surface acoustic wave.
- the filter further includes: a heat dissipation layer, the heat dissipation layer covering at least a surface area of the temperature compensation layer facing away from the interdigital transducer.
- the heat dissipation layer can improve the heat dissipation performance of the device.
- the filter further includes: an encapsulation protection layer covering the sound velocity increasing layer and the temperature compensation layer not covered by the sound velocity increasing layer facing away from the substrate On the surface.
- the package protection layer can prevent the influence of water vapor or the external environment on the internal structure of the SAW filter, and improve the reliability of the SAW filter.
- the filter further includes: an encapsulation protection layer covering the heat dissipation layer and a temperature compensation layer not covered by the heat dissipation layer on a surface facing away from the substrate .
- the package protection layer can prevent the influence of water vapor or the external environment on the internal structure of the SAW filter, and improve the reliability of the SAW filter.
- the interdigital transducer is in contact with the substrate.
- a buffer layer is provided on the surface of the substrate facing the piezoelectric material layer.
- the buffer layer can relieve the stress between the interdigital transducer and the substrate, and prevent the piezoelectric material layer and the interdigital transducer from being damaged due to excessive stress.
- the temperature compensation layer has a thickness of 1000 to between. This possible implementation manner can reduce the preparation process while ensuring a better temperature compensation effect.
- a passive device is provided on the surface of the substrate facing the piezoelectric material layer.
- a third solder pad is further provided on the surface of the temperature compensation layer facing away from the substrate, and the third solder pad is electrically connected to the second solder pad.
- a metal solder ball is further provided on the surface of the third solder pad facing away from the substrate, and the metal solder ball is used for electrical connection with an external circuit.
- a conductive plunger penetrating the substrate is provided on the substrate, and the third solder pad passes through the second solder pad, the first solder pad, and the conductive plunger Lead out.
- a second aspect of the present application provides a method for manufacturing a surface acoustic wave filter, including: forming a first bonding pad on a surface of a first substrate; performing ion implantation on the first surface of the second substrate to close A piezoelectric material layer is formed on one side of the first surface of the second substrate; a second solder pad and an interdigital transducer are formed on the piezoelectric material layer; wherein, when the first substrate and the second When the substrates are stacked and the surface of the first substrate with the first bonding pads facing the piezoelectric material layer, the first bonding pads and the second bonding pads correspond to each other one by one; The first welding pad and the second welding pad are bonded together, so that the interdigital transducer is located in the cavity enclosed by the first welding pad and the second welding pad; The second substrate is subjected to heat treatment to separate the piezoelectric material layer from the second substrate.
- the interdigital transducer may be placed in a cavity, and the inside of the cavity may be a vacuum environment or a gas environment. Acoustic waves cannot propagate in vacuum, and compared to solid media, the ability of acoustic waves to propagate in gaseous media is lower. Therefore, the acoustic wave energy is not easy to leak out from the substrate side through the cavity. Therefore, it is formed on the substrate and piezoelectric materials.
- the cavity between the layers can reduce the existence of stray mode sound waves, reduce the possibility of sound wave energy leakage from the substrate, thereby increasing the Q value and insertion loss of the SAW filter.
- the method further includes: performing heat treatment on the piezoelectric material layer Heat treatment to improve the piezoelectric properties of the piezoelectric material layer.
- the heat treatment of the piezoelectric material layer specifically includes: heat treatment of the piezoelectric material layer in a temperature range of 400 to 500°C.
- the method further includes: backing the piezoelectric material layer A temperature compensation layer is formed on the surface of the first substrate.
- the method further includes: determining the thickness of the temperature compensation layer according to design requirements. prune.
- the method further includes: positioning the temperature compensation layer on a surface facing away from the first substrate.
- a sound velocity increasing layer or a heat dissipation layer is formed on the upper surface, and the sound velocity increasing layer or the heat dissipation layer only covers a part of the surface area of the temperature compensation layer facing away from the substrate.
- the method further includes: according to design requirements, adding the sound velocity increasing layer and / Or trim the thickness of the heat dissipation layer. This possible implementation improves the product yield and performance of the SAW filter.
- the method further includes: adding the sound velocity increasing layer and/or The heat dissipation layer is annealed to eliminate the stress in the layer.
- the method further includes: backing the piezoelectric material layer
- An encapsulation protection layer is formed on the surface of the first substrate.
- the package protection layer can prevent the influence of water vapor or the external environment on the internal structure of the SAW filter, and improve the reliability of the SAW filter.
- the method further includes: forming a buffer layer on the surface of the first substrate on which the first bonding pad is formed.
- the buffer layer can relieve the stress between the interdigital transducer and the substrate, and prevent the piezoelectric material layer and the interdigital transducer from being damaged due to excessive stress.
- the method further includes: forming a third solder pad on the surface of the temperature compensation layer facing away from the first substrate, and the third solder pad is connected to the first substrate. Two pad connections.
- the third solder pad after forming the third solder pad, it further includes: forming a metal solder ball on the surface of the third solder pad facing away from the first substrate, and the metal solder ball is used to connect to the outside The electrical connection of the circuit.
- the third aspect of the present application provides a radio frequency front-end chip, including a surface acoustic wave filter, a low noise amplifier, a power amplifier and a data transmission interface; wherein the surface acoustic wave filter is the first aspect and its possible In the surface acoustic wave filter described in any implementation manner, the low noise amplifier, power amplifier, and data transmission interface are located inside the cavity and on the surface of the substrate facing the piezoelectric material layer.
- the radio frequency front-end chip provided by the third aspect of this application includes the surface acoustic wave filter described in the first aspect of this application and any of its possible implementations, correspondingly, the radio frequency front-end chip has the aforementioned first aspect of the application And the beneficial effects of the surface acoustic wave filter described in any of its possible implementations.
- a fourth aspect of the present application provides a mobile terminal, including: a communication module, the communication module includes a surface acoustic wave filter, and the surface acoustic wave filter is the first aspect and any possible implementation manner thereof The surface acoustic wave filter described in.
- the mobile terminal provided by the fourth aspect of this application includes the surface acoustic wave filter described in the first aspect of this application and any of its possible implementations, the mobile terminal has the above-mentioned first aspect of the application and its The beneficial effects of the surface acoustic wave filter described in any possible implementation manner.
- the surface acoustic wave filter provided by the present application includes a substrate and a piezoelectric material layer that are opposed to each other, wherein a cavity is provided between the substrate and the piezoelectric material layer; the piezoelectric material layer faces the surface of the substrate An interdigital transducer is provided; the interdigital transducer is located in the cavity.
- the inside of the cavity can be a vacuum environment or a gas environment. Acoustic waves cannot propagate in vacuum, and compared to solid media, the ability of acoustic waves to propagate in gaseous media is lower. Therefore, compared with the prior art, due to the existence of cavities, the surface acoustic filter provided by the present application is reduced The ability of sound wave energy to leak out of the substrate.
- the spurious mode sound waves of the surface acoustic wave filter are caused by the leaked sound wave energy. Therefore, the sound wave energy whose leakage ability is reduced reduces the existence of the spurious mode sound waves of the surface acoustic wave filter, thereby making it more A large amount of sound wave energy can be transmitted through a desired transmission path (surface transmission path), thereby improving the Q value and insertion loss of the SAW filter.
- FIG. 1 is a schematic diagram of a SAW filter structure provided by an embodiment of the present application.
- FIG. 2 is a schematic diagram of the structure of an interdigital transducer provided by an embodiment of the present application
- FIG. 3 is a schematic diagram of another SAW filter structure provided by an embodiment of the present application.
- FIG. 4 is a schematic diagram of another SAW filter structure provided by an embodiment of the present application.
- FIG. 5 is a schematic diagram of another SAW filter structure provided by an embodiment of the present application.
- Fig. 6 is a schematic diagram of another SAW filter structure provided by an embodiment of the present application.
- FIG. 7 is a schematic flowchart of a method for manufacturing a SAW filter according to an embodiment of the present application.
- 8(1) to 8(7) are schematic structural diagrams corresponding to a series of manufacturing processes of a SAW filter manufacturing method provided by an embodiment of the present application;
- FIG. 9 is a schematic flowchart of another SAW filter manufacturing method provided by an embodiment of the present application.
- 10(1) to 10(4) are schematic structural diagrams corresponding to a series of manufacturing processes of another SAW filter manufacturing method provided by an embodiment of the present application;
- FIG. 11 is a schematic structural diagram of a radio frequency front-end chip provided by an embodiment of the present application.
- FIG. 12 is a schematic structural diagram of a mobile terminal provided by an embodiment of the present application.
- the SAW filter includes a substrate and a piezoelectric material layer arranged oppositely, a cavity is arranged between the substrate and the piezoelectric material layer; and a side wall of the cavity is provided with a side wall for bonding the substrate and the piezoelectric material layer.
- the bonding pad of the piezoelectric material layer; the surface of the piezoelectric material layer facing the substrate is provided with an interdigital transducer; the interdigital transducer is located in the cavity.
- the inside of the cavity can be a vacuum environment or a gas environment. Acoustic waves cannot propagate in vacuum, and compared to solid media, the ability of acoustic waves to propagate in gaseous media is lower. Therefore, compared with the prior art, due to the existence of cavities, the surface acoustic filter provided by the present application is reduced The ability of sound wave energy to leak out of the substrate. Moreover, the spurious mode sound waves of the surface acoustic wave filter are caused by the leaked sound wave energy.
- the sound wave energy whose leakage ability is reduced reduces the existence of the spurious mode sound waves of the surface acoustic wave filter, thereby making it more A large amount of sound wave energy can be transmitted through a desired transmission path (surface transmission path), thereby improving the Q value and insertion loss of the SAW filter.
- a SAW filter provided by an embodiment of the present application includes:
- the substrate 10 and the piezoelectric material layer 20 are arranged oppositely, and a cavity 30 is provided between the substrate 10 and the piezoelectric material layer 20;
- a first solder pad 101 is provided on the surface of the substrate 10 facing the piezoelectric material layer 20; the first solder pad 101 is located on the sidewall of the cavity 30;
- the piezoelectric material layer 20 is provided with a second solder pad 201 and an interdigital transducer 202 on the surface facing the substrate 10; the interdigital transducer 202 is located in the cavity 30; the second solder pad 201 is located on the sidewall of the cavity 30 on;
- the first bonding pad 101 and the second bonding pad 201 are laminated and bonded together up and down.
- a third bonding pad 203 may be provided on the surface of the piezoelectric material layer 20 facing away from the substrate 10, wherein the third bonding pad 203 and the second bonding pad 201 are electrically connected.
- the second solder pad 201 and the third solder pad 203 are arranged up and down opposite to each other, and a conductive via 204 is provided in the piezoelectric material layer 20 area where the second solder pad 201 and the third solder pad 203 are opposite The conductive via 204 realizes the electrical connection between the third solder pad 203 and the second solder pad 201.
- the third solder pad 203 can also be used as a test solder pad to test the performance of the SAW filter in the process of manufacturing the SAW filter, so as to determine the passband of the SAW filter according to the test result.
- the frequency is fine-tuned to improve the device yield.
- a metal bonding pad 205 is also provided on the surface of the third bonding pad 203 facing away from the piezoelectric material layer 20 to realize the connection between the SAW filter and the external circuit.
- the metal bonding pad 205 may be a metal solder ball. .
- the cavity is a closed cavity structure, the sidewall of which may be composed of a closed interlayer dielectric layer or a metal interconnection layer, and the first pad 101 may be arranged on the side of the cavity 30 On the wall.
- the first bonding pad 101 may be a metal bump or a metal solder ball.
- the second pad 201 can be a metal bump or a metal solder ball.
- the substrate 10 is a supporting substrate, which may be a silicon substrate, a glass substrate, or a sapphire substrate.
- a passive device (not shown in FIG. 1) may be provided on the surface of the substrate 10 facing the piezoelectric material layer 20, and the passive device may be combined with the SAW filter. Make a match.
- the passive device may be a device such as a capacitor or an inductor.
- the piezoelectric material layer 20 can be obtained by implanting ions to a certain depth into the surface of the piezoelectric material substrate, and then separating them from the interface with the highest implanted ion concentration.
- the material of the piezoelectric material substrate may be lithium niobate (LiNbO 3 ) or lithium tantalate (LiTaO 3 ).
- the type of implanted ions can be hydrogen ions, and the depth of implantation can be determined according to the designed thickness of the piezoelectric material layer. And according to the depth of implantation to select the implantation energy.
- the interdigital transducer 202 is formed on the surface of the piezoelectric material layer 20 with a metal pattern shaped like a cross of the fingers of two hands, and its function is to realize sound-to-electricity conversion. In addition, the interdigital transducer 202 can also play a filtering role. As an example, FIG. 2 shows a top view of the interdigital transducer 202.
- the metal material and process method used in the interdigital transducer 202 are not particularly limited.
- the preparation of the interdigital transducer 202 can be completed by a lift-off process.
- the metal material used in the interdigital transducer 202 may be a metal material with a relatively high density such as Au, Ta, W, or Cu.
- the thickness of the interdigital transducer 202 can be between 1000 and between.
- both the first solder pad 101 and the second solder pad 201 may be used as bonding pads.
- the piezoelectric material layer 20 and the substrate 10 are bonded together through the first bonding pad 101 and the second bonding pad 201, wherein the first bonding pad 101 and the second bonding pad 201 correspond one-to-one, when the piezoelectric material layer 20
- the first solder pad 101 and the second solder pad 201 are aligned one by one, so that the piezoelectric material layer 20 and the substrate 10 are bonded together through a bonding process.
- the second soldering pad 201 can also be used to realize electrical connection between the electrodes in the interdigital transducer 202 at the same time.
- the bonding pads used to realize the electrical connection between the electrodes in the interdigital transducer 202 and the bonding pads used for bonding can be separate.
- the first bonding pad 101 may be a bonding pad formed by growing polysilicon by a Low Pressure Chemical Vapor Deposition (LPCVD) method and formed by an etching method.
- LPCVD Low Pressure Chemical Vapor Deposition
- the first bonding pad 101 may also be a metal bonding pad formed by an electroplating process or an electron beam evaporation deposition process.
- the second bonding pad 201 may be a metal bonding pad formed by an electroplating process or an electron beam evaporation deposition process.
- the material of the metal pad can be gold, and the thickness can be 2000 to between.
- an adhesion layer may also be provided between the first solder pad 101 and the second solder pad 201 (Not shown in FIG. 1), the material of the adhesion layer may be Ti or Cr.
- solder pads may be provided only on the surface of the substrate 10 facing the piezoelectric material layer 20, and the solder pads may be directly bonded to the surface of the piezoelectric material layer 20 facing the substrate 10. on.
- solder pads may be provided only on the surface of the piezoelectric material layer 20 facing the substrate 10, and the solder pads are directly bonded to the surface of the substrate 10 facing the piezoelectric material layer 20.
- the substrate 10 and the piezoelectric material layer 20 are disposed opposite to each other, and the cavity 30 is located between the substrate 10 and the piezoelectric material layer 20; and will be disposed on the piezoelectric material.
- the interdigital transducer 202 on the surface of the layer 20 is located in the cavity 30.
- the inside of the cavity can be a vacuum environment or a gas environment. Acoustic waves cannot propagate in vacuum, and compared to solid media, the ability of acoustic waves to propagate in gaseous media is lower. Therefore, compared with the prior art, due to the existence of cavities, the surface acoustic filter provided by the present application is reduced The ability of sound wave energy to leak out of the substrate.
- the spurious mode sound waves of the surface acoustic wave filter are caused by the leaked sound wave energy. Therefore, the sound wave energy whose leakage ability is reduced reduces the existence of the spurious mode sound waves of the surface acoustic wave filter, thereby making it more A large amount of sound wave energy can be transmitted through a desired transmission path (surface transmission path), thereby improving the Q value and insertion loss of the SAW filter.
- the interdigital transducer 202 is not in contact with the substrate 10, and there is a certain gap between the two, which can reduce the possibility of acoustic energy leaking from the substrate 10 side.
- the interdigital transducer 202 is in contact with the substrate 10, which can increase the mechanical support force of the cavity 30 and improve the structural stability of the SAW filter.
- whether the interdigital transducer 202 is in contact with the substrate 10 can be achieved by adjusting the height of the interdigital transducer 202, the first welding pad 101 and the second welding pad 201. Specifically, when the height of the interdigital transducer 202 is equal to the sum of the heights of the first bonding pad 101 and the second bonding pad 201, the interdigital transducer 202 can be brought into contact with the substrate 10. When the height of the interdigital transducer 202 is less than the sum of the heights of the first bonding pad 101 and the second bonding pad 201, it can be achieved that the interdigital transducer 202 does not contact the substrate 10.
- a buffer layer (not shown in FIG. 3) may be provided on the surface of the substrate 10 facing the piezoelectric material layer 20, and the buffer layer The stress between the interdigital transducer 202 and the substrate 10 can be relieved, and the piezoelectric material layer 20 and the interdigital transducer 202 can be prevented from being damaged due to excessive stress.
- the material of the buffer layer can be softened during the bonding process of the substrate 10 and the piezoelectric material layer 20, so as to ensure sufficient bonding between the interdigital transducer 202 and the buffer layer, while retaining the substrate 10 and Cavities between layers 20 of piezoelectric material.
- the buffer layer may be made of resin material.
- the SAW filter may also include a temperature compensation layer 206, and the temperature compensation layer 206 is located on the surface of the piezoelectric material layer 20 facing away from the substrate 10.
- the third bonding pad 203 is located on the surface of the temperature compensation layer 206 facing away from the substrate 10, and the conductive via 204 not only penetrates the piezoelectric material layer 20, but also penetrates the temperature compensation layer 206 up and down.
- the temperature compensation layer 206 has a positive temperature coefficient characteristic, which can alleviate the problem that the passband frequency of the SAW filter drifts with temperature changes to a certain extent.
- the material of the temperature compensation layer 206 may be silicon dioxide.
- the surface of the piezoelectric material layer 20 facing away from the substrate 10 is a completely flat surface, there are many options for the deposition process for forming the temperature compensation layer 206.
- plasma enhanced chemical vapor deposition Plasma Enhanced Chemical Vapor Deposition PECVD
- LPCVD LPCVD
- PVD Physical Vapor Deposition
- the thickness and compactness of the temperature compensation layer 206 will affect the equivalent sound velocity of the sound wave. If the thickness is too thin or the compactness is too poor, the temperature compensation effect will not be obvious. If the temperature is too thick, it needs to be prepared with a higher density The large interdigital transducer electrode makes the preparation process more complicated. Therefore, as an example, the thickness of the temperature compensation layer 206 may be In between, in order to take into account the above issues.
- the SAW filter shown in FIG. 4 is improved on the basis shown in FIG. 1.
- the SAW filter provided with a temperature compensation layer can also be shown in FIG. 3 Improved on the basis of the SAW filter shown.
- the leakage of acoustic energy on the side of the substrate 10 can be reduced, thereby improving the Q value and insertion loss of the SAW filter.
- this application also provides another embodiment of the SAW filter to reduce the leakage of acoustic energy on the side of the piezoelectric material layer, thereby Further improve the Q value and insertion loss of the SAW filter.
- the SAW filter provided by the embodiment of the present application may also include a sound velocity increasing layer 207, which is located on the surface of the temperature compensation layer 206 facing away from the substrate 10. .
- the sound velocity increasing layer 207 can increase the equivalent sound velocity of the surface acoustic wave.
- the sound velocity increasing layer 207 may only be provided on the surface area of the temperature compensation layer 206 facing away from the interdigital transducer 202 instead of covering the entire surface of the temperature compensation layer 206.
- the sound velocity increasing layer 207 may also cover the entire surface of the temperature compensation layer 206.
- the material of the sound velocity increasing layer 207 may be a material with high acoustic resistance, such as AlN, Al 2 O 3 , SiC, SiN, SiON, or the like.
- the thickness of the sound velocity increasing layer 207 may be
- the acoustic wave energy does not easily leak from the substrate 10 side through the cavity 30.
- the temperature compensation layer 206 and the sound velocity increasing layer 207 provided on the surface of the piezoelectric material layer 20 opposite to the substrate 10 can confine the sound wave energy between the temperature compensation layer 206 and the sound velocity increasing layer 207, so that the sound wave energy is not It is easy to leak from the piezoelectric material layer 20 side. Therefore, in the SAW filter shown in Fig. 5, the acoustic wave energy cannot not only leak from the substrate side, but also cannot leak from the piezoelectric material layer side. Therefore, the SAW filter further reduces the acoustic wave energy leakage and further improves the SAW. The Q value and insertion loss of the filter.
- the sound velocity increasing layer 207 shown in FIG. 5 may be replaced with a heat dissipation layer, which may be made of a material with high thermal conductivity.
- the material with high thermal conductivity may be AlN, Al 2 O 3 , SiC, SiN, SiON, or the like.
- the thickness of the heat dissipation layer can be
- the high acoustic resistance material used to prepare the sound velocity increasing layer 207 and the heat dissipation material used to prepare the heat dissipation layer may be the same material, the sound velocity increasing layer 207 and the heat dissipation layer may have the same layer structure.
- the temperature compensation layer 206 may be opposite to the substrate 10 On the surface, a sound velocity increasing layer and a heat dissipation layer are simultaneously formed on the surface.
- the upper and lower positional relationship between the sound velocity increasing layer and the heat dissipation layer is not limited.
- this application also provides another implementation of the SAW filter.
- the SAW filter provided by the embodiment of the present application includes the various structures shown in FIG. 5, and may also include:
- the encapsulation protection layer 208 covers the surface of the sound velocity increasing layer 207 and the temperature compensation layer 206 not covered by the sound velocity increasing layer 207 facing away from the substrate 10.
- the package protection layer 208 can prevent damage to the internal structure of the SAW during the packaging process.
- the package protection layer 208 can isolate the internal structure of the SAW from the external environment such as water vapor, thereby improving the reliability of the device .
- the encapsulation protection layer 208 can also increase the mechanical strength of the thin-film piezoelectric structure and suppress the occurrence of lamb wave modes.
- the material of the encapsulation protection layer 208 may be selected from at least one of poly-p-phenylene benzobisoxazole (PBO) or polymide (PI).
- PBO poly-p-phenylene benzobisoxazole
- PI polymide
- the third bonding pad 203 is located on the surface of the package protection layer 208 facing away from the substrate 10, and the conductive via 204 penetrates the piezoelectric material layer 20 and the temperature compensation layer 206, except for The package protection layer 208 is also penetrated up and down.
- the internal electrical signals can pass through the first bonding pad 101, the second bonding pad 201, and the third bonding pad 203, as well as the metal solder balls provided on the side of the piezoelectric material layer 20 and the external circuit. Realize electrical connection.
- the packaging form can be more flexible.
- a conductive plunger may also be provided on the substrate 10, and the electrical signal inside the SAW filter may pass through the first pad 101, the second pad 201, and the third pad 203 and The conductive plunger is led out to realize electrical connection with the external circuit.
- the present application also provides specific implementations of the manufacturing method of the SAW filter.
- a method for manufacturing a SAW filter provided by an embodiment of the present application includes:
- an LPCVD process may be used to grow a conductive layer on a surface of the first substrate 10, and then, the first bonding pad 101 may be formed on a surface of the first substrate 10 by an etching method.
- the material of the conductive layer may be polysilicon or conductive metal.
- the first substrate 10 is a supporting substrate, which may be a silicon substrate, a glass substrate, or a sapphire substrate.
- a passive device (not shown in FIG. 8(1)) can also be formed on at least one surface of the first substrate, and the passive device can be used for SAW filter is matched.
- the passive device may be a device such as a capacitor or an inductor.
- S702 Perform ion implantation on the first surface of the second substrate to form a piezoelectric material layer near the first surface of the second substrate.
- This step may be specifically: obtaining ion implantation energy according to the designed thickness of the piezoelectric material layer, and performing ions from the first surface of the second substrate 20' into the interior of the second substrate 20' according to the obtained ion implantation energy. Inject, thereby forming the piezoelectric material layer 20 on the side close to the first surface of the second substrate 20'.
- the implanted energy may be 100-150 KeV
- the implanted ion dose may be 3*10e16-8*10e16 atoms/cm 2 .
- the second substrate 20' may be a piezoelectric material substrate, such as a lithium niobate substrate or a lithium tantalate substrate.
- the dotted line represents the position with the highest ion concentration.
- S703 forming a second solder pad and an interdigital transducer on the piezoelectric material layer; wherein, when the first substrate and the second substrate are stacked and the first substrate is formed with a first solder When the surface of the pad faces the piezoelectric material layer, the first solder pads and the second solder pads correspond to each other one by one.
- This step can be specifically: forming the second bonding pad 201 and the interdigital transducer 202 on the surface of the piezoelectric material layer 20 through a patterning process.
- the metal material and process method used in the interdigital transducer 202 are not particularly limited.
- the preparation of the interdigital transducer 202 can be completed by a lift-off process.
- the metal material used in the interdigital transducer 202 may be a metal material with a relatively high density such as Au, Ta, W, or Cu.
- the thickness of the interdigital transducer 202 can be between 1000 and between.
- the second bonding pad 201 may be formed by an electroplating process or an electron beam evaporation deposition process.
- the thickness of the second pad can be 2000 to between.
- S704 Bond the first solder pad and the second solder pad corresponding to each other one by one, so that the interdigital transducer is located around the first solder pad and the second solder pad. Into the cavity.
- This step may specifically include: placing the first substrate 10 and the second substrate 20' opposite each other in such a way that the surface on the first substrate 10 with the first bonding pad 101 faces the piezoelectric material layer on the second substrate 20', and making The first bonding pad 101 and the second bonding pad 201 corresponding to each other are aligned one by one, and then the first bonding pad 101 and the second bonding pad 201 corresponding to each other are bonded together by a bonding process, so that the A cavity 30 is formed between a substrate 10 and a second substrate 20'.
- the first welding pad 101 and the second welding pad 201 form the sidewall of the cavity 30, and the interdigital transducer 202 is located in the cavity 30.
- the bonding process used in this step may be a eutectic bonding process.
- the bonding temperature can be 300-400°C and the time is maintained for 30-60 min.
- S705 Perform heat treatment on the second substrate to separate the piezoelectric material layer from the second substrate.
- This step can specifically be: heat treatment of the structure formed by S704 at 250 to 400°C. During the heat treatment, the second substrate 20' will generate microbubbles from the position with the highest implanted ion concentration. After the stress is applied, the piezoelectric material The layer 20 is separated from the second substrate 20'.
- S706 Perform heat treatment on the piezoelectric material layer to improve the piezoelectric characteristics of the piezoelectric material layer.
- the embodiment of the present application may heat the piezoelectric material layer to improve the piezoelectric performance.
- the piezoelectric properties of the material layer may be heat the piezoelectric material layer to improve the piezoelectric performance.
- the temperature range of the heat treatment used in this step is between 300-600°C, more specifically, the temperature range of the heat treatment is between 400-500°C, and the duration is 2-4 hours.
- This step can be specifically as follows: using an etching process to form a through hole 204' on the area of the piezoelectric material layer 20 opposite to the second bonding pad 201.
- this step can be specifically as follows: first, a conductive material layer is formed on the surface of the piezoelectric material layer 20 facing away from the first substrate 10, wherein, while the conductive material layer is formed, the conductive material is filled into the through holes 204', so that the through hole 204' forms a conductive through hole 204.
- the SAW filter shown in FIG. 1 or FIG. 3 may be formed.
- whether the interdigital transducer 202 is in contact with the substrate 10 can be achieved by adjusting the height of the interdigital transducer 202, the first welding pad 101 and the second welding pad 201.
- the interdigital transducer 202 may not contact the substrate 10, thereby forming the structure shown in FIG. 1.
- the interdigital transducer 202 When the height of the interdigital transducer 202 is equal to the sum of the heights of the first bonding pad 101 and the second bonding pad 201, the interdigital transducer 202 can be in contact with the substrate 10, thereby forming the structure shown in FIG. 3.
- a buffer layer is formed on the surface of the first substrate 10 on which the first pad is formed.
- the material of the buffer layer can become soft during the bonding process of the substrate 10 and the piezoelectric material layer 20, so as to ensure sufficient bonding between the interdigital transducer 202 and the buffer layer, while retaining the substrate 10 and the piezoelectric material layer 20 The cavity between.
- the buffer layer may be made of resin material.
- the interdigital transducer 202 may be placed in the cavity 30, and the inside of the cavity may be a vacuum environment or a gas environment. Acoustic waves cannot propagate in vacuum, and compared to solid media, the ability of acoustic waves to propagate in gaseous media is lower. Therefore, the acoustic wave energy is not easy to leak out from the side of the substrate 10 through the cavity 30. Therefore, it is formed on the substrate 10 and The cavities 30 between the piezoelectric material layers 20 can reduce the existence of stray mode acoustic waves, reduce the possibility of acoustic energy leakage from the substrate 10, thereby increasing the Q value and insertion loss of the SAW filter.
- Another method for manufacturing a SAW filter includes the following steps:
- S901 to S906 are the same as the above S701 to S706, and for the sake of brevity, the detailed description is omitted here.
- PECVD PECVD
- LPCVD LPCVD
- PVD PVD
- the temperature compensation layer 206 has a positive temperature coefficient characteristic, which can alleviate the problem that the passband frequency of the SAW filter drifts with temperature changes to a certain extent.
- the material of the temperature compensation layer 206 may be silicon dioxide.
- the thickness and compactness of the temperature compensation layer 206 will affect the equivalent sound velocity of the sound wave. If the thickness is too thin or the compactness is too poor, the temperature compensation effect will not be obvious. If the temperature is too thick, it needs to be prepared with a higher density The large interdigital transducer electrode makes the preparation process more complicated. Therefore, as an example, the thickness of the temperature compensation layer 206 may be In between, in order to take into account the above issues.
- This step can be specifically as follows: after the temperature compensation layer 206 is formed, the performance of the SAW filter is tested, and the target performance of the SAW filter design is compared with the actual performance obtained by the test. If the actual performance tested is inconsistent with the target performance, The particle grinding process can be used to differentially trim the thickness of the temperature compensation layer on different areas of the first substrate, so that the passband frequencies of the SAW filters in different areas are consistent, and the passband frequency of the SAW filters can be adjusted. In turn, the uniformity and product yield of the SAW filter are improved.
- a PECVD process can be used to form a sound velocity increasing layer 207 on the surface of the temperature compensation layer 206 facing away from the first substrate 10, and the sound velocity increasing layer 207 can increase the equivalent sound velocity of the surface acoustic wave.
- the sound velocity increasing layer 207 may be only provided on the surface area of the temperature compensation layer 206 facing away from the interdigital transducer 202 instead of covering the entire surface of the temperature compensation layer 206.
- the sound velocity increasing layer 207 when the sound velocity increasing layer 207 is made of a material with high thermal conductivity, the sound velocity increasing layer 207 can also serve as a heat dissipation layer, thereby improving the heat dissipation performance of the SAW filter.
- the material of the sound velocity increasing layer 207 may be a material with high acoustic resistance, such as AlN, Al 2 O 3 , SiC, SiN, SiON, or the like.
- the thickness of the sound velocity increasing layer 207 may be
- S909 can be replaced by: forming a heat dissipation layer on the surface of the temperature compensation layer facing away from the first substrate.
- the high acoustic resistance material used to prepare the sound velocity increasing layer 207 and the heat dissipation material used to prepare the heat dissipation layer may be the same material, the sound velocity increasing layer 207 and the heat dissipation layer may have the same layer structure.
- the high acoustic resistance material used to prepare the sound velocity increasing layer 207 and the heat dissipation material used to prepare the heat dissipation layer are different kinds of materials, in order to make the prepared SAW filter both reduce the sound wave energy on the piezoelectric material layer side Leakage can also improve the heat dissipation performance of the SAW filter.
- a laminated sound velocity increasing layer and a heat dissipation layer can be formed on the surface of the temperature compensation layer 206 facing away from the substrate 10 at the same time.
- the upper and lower positional relationship between the sound velocity increasing layer and the heat dissipation layer is not limited.
- This step can be specifically as follows: after the sound velocity increasing layer 207 is formed, the performance of the SAW filter is tested, and the target performance of the SAW filter design is compared with the actual performance obtained by the test. If the actual performance tested is inconsistent with the target performance, The particle grinding process can be used to trim the thickness of the sound velocity increasing layer 207 on different areas of the first substrate on different areas of the first substrate, so that the passband frequencies of the SAW filters in different areas are consistent, and the SAW filter can be improved. The adjustment of the passband frequency further improves the uniformity and product yield of SAW filters.
- the package protection layer 208 can prevent damage to the internal structure of the SAW during the packaging process.
- the package protection layer 208 can isolate the internal structure of the SAW from the external environment such as water vapor, thereby improving the reliability of the device .
- the encapsulation protection layer 208 can also increase the mechanical strength of the thin-film piezoelectric structure and suppress the occurrence of lamb wave mode.
- the material of the encapsulation protection layer 208 may be selected from at least one of PBO or PI.
- S912 Etch the package protection layer, the temperature compensation layer and the piezoelectric material layer to form through holes.
- This step can be specifically as follows: etching the package protection layer 208, the temperature compensation layer 206 and the piezoelectric material layer 20 above the second bonding pad 201 to form the penetrating package protection layer 208, the temperature compensation layer 206 and the piezoelectric material layer 20 The through hole 204'.
- the through hole 204' communicates with the second pad 201.
- S913 to S914 are the same as S708 to S709, and for the sake of brevity, detailed description is omitted here. Finally, the SAW filter structure shown in Figure 6 is formed.
- the third solder pad 203 can be used as a test solder pad, and the performance of the SAW filter can be tested by using the third solder pad 203 to obtain the test result of the SAW filter performance.
- the surface of the piezoelectric material layer 20 facing away from the first substrate 10 is a flat surface, there are more choices in the process for forming the temperature compensation layer 206, and the process for forming the temperature compensation layer 206 is less difficult and unnecessary After the temperature compensation layer 206 is formed, a flattening process is performed, thereby reducing the chemical mechanical polishing process, simplifying the process flow, and reducing the manufacturing cost.
- the equivalent sound velocity of the surface acoustic wave is related to the thickness of the temperature compensation layer 206, the sound velocity increasing layer 207, and the heat dissipation layer disposed on the surface of the piezoelectric material layer 20 facing away from the interdigital transducer, in the embodiment of the present application
- a trimming process can be inserted to trim the thickness of each layer, thereby improving the product yield and quality of the SAW filter. performance.
- the internal electrical signals can pass through the first pad 101, the second pad 201, and the third pad 203 and the piezoelectric material layer 20—
- the metal solder ball on the side is electrically connected with the external circuit.
- the packaging form can be more flexible.
- a conductive plunger may also be provided on the first substrate 10, and the electrical signal inside the SAW filter may pass through the first pad 101, the second pad 201, and the third pad. 203 and the conductive plunger are drawn out from the side of the first substrate 10 facing away from the piezoelectric material layer 20, so as to realize electrical connection with an external circuit.
- the bonding pads for bonding are formed on the surfaces of the first substrate 10 and the second substrate 20'.
- a bonding pad may be formed only on the first substrate 10, and the bonding pad may be directly soldered on the surface of the second substrate 20'.
- the RF front-end chip includes a surface acoustic wave filter 111, a low noise amplifier 112, a power amplifier 113, and a data transmission interface 114;
- the surface acoustic wave filter is the surface acoustic wave filter described in any of the foregoing embodiments.
- the surface acoustic wave filter shown in FIG. 11 is the surface acoustic wave filter shown in FIG. 1 described above.
- the low noise amplifier 112 the power amplifier 113 and the data transmission interface 114 are located inside the cavity 30 and on the surface of the substrate 10 facing the piezoelectric material layer 20.
- This application also provides a specific implementation of the mobile terminal.
- the mobile terminal provided by the embodiment of the present application includes a communication module 121.
- the communication module 121 includes a surface acoustic wave filter 1211.
- the surface acoustic wave filter 1211 may be the surface acoustic wave provided by any of the foregoing implementations. filter.
- the mobile terminal described in the embodiment of the present application may be a mobile phone, a tablet computer, and so on.
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Abstract
一种声表面波滤波器及其制造方法，该滤波器相对设置的基底（10）和压电材料层（20），其中，基底（10）和压电材料层（20）之间设置有空腔（30）；压电材料层（20）朝向基底（10）的表面上设置有叉指换能器（202）；叉指换能器（202）位于所述空腔（30）内。该空腔（30）内部可以为真空环境，也可以为气体环境。而声波在真空中不能传播，且相较于固体介质，声波在气体介质中的传播能力较低，所以，声波能量不容易通过空腔（30）从基底（10）泄露出去，因而，形成于基底（10）和压电材料层（20）之间的空腔（30）可以减少杂散模式的声波的存在，降低了声波能量从基底（10）泄露的可能，从而提高了SAW滤波器的Q值和插入损耗。此外，还公开了一种包含该声表面波滤波器的射频前端芯片和移动终端。
Description
本申请涉及半导体设备技术领域，尤其涉及一种声表面波滤波器及其制造方法，还涉及一种包含该声表面波滤波器的射频前端芯片和移动终端。
随着移动终端小型化的要求，在射频前端领域，小于6GHz的滤波器一般采用声表面波(Surface Acoustic Wave,SAW)或体声波(Body Acoustic Wave，BAW)技术。其中，相较于BAW滤波器，SAW滤波器工艺相对简单、成本相对较低的优势，在小于2GHz的频段内被广泛应用。
传统的SAW滤波器结构是在基底上直接形成叉指换能器(Interdigital Transducer，IDT)。该SAW滤波器结构会导致声波能量从基底泄露，导致SAW滤波器的品质因子(Quality Factor，Q)和插入损耗(Insertion loss，IL)偏低。
发明内容
有鉴于此，本申请提供了一种声表面波滤波器及其制造方法。此外，本申请还提供了一种包含该声表面波滤波器的射频前端芯片和移动终端。
为了解决上述技术问题，本申请采用了如下技术方案：
本申请的第一方面提供了一种声表面波滤波器，包括：相对设置的基底和压电材料层，所述基底和所述压电材料层之间设置有空腔；所述空腔的侧壁上设置有用于键合所述基底和所述压电材料层的焊垫；所述压电材料层朝向所述基底的表面上设置有叉指换能器；所述叉指换能器位于所述空腔内。
第一方面提供的声表面波滤波器包括相对设置的基底和压电材料层，其中，基底和压电材料层之间设置有空腔；压电材料层朝向基底的表面上设置有叉指换能器；叉指换能器位于所述空腔内。该空腔内部可以为真空环境，也可以为气体环境。而声波在真空中不能传播，且相较于固体介质，声波在气体介质中的传播能力较低，所以，声波能量不容易通过空腔从基底泄露出去，因而，形成于基底和压电材料层之间的空腔可以减少杂散模式的声波的存在，降低了声波能量从基底泄露的可能，从而提高了SAW滤波器的Q值和插入损耗。
在一种可能的实现方式中，所述焊垫包括位于所述基底朝向所述压电材料层表面上的第一焊垫，和/或，位于所述压电材料层朝向所述基底表面上的第二焊垫；所述第一焊垫和所述第二焊垫层叠设置。该可能的实现方式更加方便基底和压电材料层的键合。
在一种可能的实现方式中，所述滤波器还包括：温度补偿层，所述温度补偿层位于所述压电材料层背对所述基底的表面上。该可能的实现方式能够一定程度上缓解SAW滤波器的通带频率随温度变化发生漂移的问题。
在一种可能的实现方式中，所述滤波器还包括：声速增加层，所述声速增加层至少覆 盖所述温度补偿层背对所述叉指换能器的表面区域。该声速增加层可以提高声表面波的等效声速。
在一种可能的实现方式中，所述滤波器还包括：散热层，所述散热层至少覆盖所述温度补偿层背对所述叉指换能器的表面区域。该散热层能够提高器件的散热性能。
在一种可能的实现方式中，所述滤波器还包括：封装保护层，所述封装保护层覆盖所述声速增加层以及未被所述声速增加层覆盖的温度补偿层背对所述基底的表面上。该封装保护层能够防止水汽或外界环境对SAW滤波器内部结构的影响，提高SAW滤波器的可靠性。
在一种可能的实现方式中，所述滤波器还包括：封装保护层，所述封装保护层覆盖所述散热层以及未被所述散热层覆盖的温度补偿层背对所述基底的表面上。该封装保护层能够防止水汽或外界环境对SAW滤波器内部结构的影响，提高SAW滤波器的可靠性。
在一种可能的实现方式中，所述叉指换能器与所述基底接触。
在一种可能的实现方式中，所述基底朝向所述压电材料层的表面上设置有缓冲层。该缓冲层可以缓解叉指换能器与基底之间的应力，防止其间因应力过大导致压电材料层和叉指换能器的损伤。
在一种可能的实现方式中，所述温度补偿层的厚度在1000至
之间。该可能的实现方式在保证较好的温度补偿效果的同时，能够降低制备工艺。
在一种可能的实现方式中，所述基底朝向所述压电材料层的表面上设置有无源器件。
在一种可能的实现方式中，所述温度补偿层背对所述基底的表面上还设置有第三焊垫，所述第三焊垫与所述第二焊垫电连接。
在一种可能的实现方式中，所述第三焊垫背对所述基底的表面上还设置有金属焊球，所述金属焊球用于与外部电路的电连接。
在一种可能的实现方式中，所述基底上设置有贯穿所述基底的导电柱塞，所述第三焊垫通过所述第二焊垫、所述第一焊垫以及所述导电柱塞引出。
本申请的第二方面提供了一种声表面波滤波器的制造方法，包括：在第一基底的一表面上形成第一焊垫；在第二基底的第一表面进行离子注入，以在靠近所述第二基底的第一表面一侧形成压电材料层；在所述压电材料层上形成第二焊垫和叉指换能器；其中，当所述第一基底与所述第二基底层叠放置且所述第一基底的形成有第一焊垫表面朝向所述压电材料层时，所述第一焊垫与所述第二焊垫一一相互对应；将一一相互对应的所述第一焊垫和所述第二焊垫键合在一起，从而使所述叉指换能器位于所述第一焊垫和所述第二焊垫围成的空腔内；对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来。
在本申请第二方面提供的SAW滤波器的制造方法中，可以将叉指换能器置于空腔内，而该空腔内部可以为真空环境，也可以为气体环境。而声波在真空中不能传播，且相较于固体介质，声波在气体介质中的传播能力较低，所以，声波能量不容易通过空腔从基底侧 泄露出去，因而，形成于基底和压电材料层之间的空腔可以减少杂散模式的声波的存在，降低了声波能量从基底泄露的可能，从而提高了SAW滤波器的Q值和插入损耗。
在一种可能的实现方式中，所述对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来之后，还包括：对所述压电材料层进行热处理，以提高所述压电材料层的压电特性。
在一种可能的实现方式中，所述对所述压电材料层进行热处理，具体包括：在400至500℃的温度范围内对所述压电材料层进行热处理。
在一种可能的实现方式中，所述对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来之后，还包括：在所述压电材料层背对所述第一基底的表面上形成温度补偿层。
在一种可能的实现方式中，所述在所述压电材料层背对所述第一基底的表面上形成温度补偿层之后，还包括：根据设计需要，对所述温度补偿层的厚度进行修剪。
在一种可能的实现方式中，在所述压电材料层背对所述第一基底的表面上形成温度补偿层之后，还包括：在所述温度补偿层背对所述第一基底的表面上形成声速增加层或散热层，所述声速增加层或散热层仅覆盖所述温度补偿层背对所述基底的部分表面区域。
在一种可能的实现方式中，所述在所述温度补偿层背对所述第一基底的表面上形成声速增加层或散热层之后，还包括：根据设计需要，对所述声速增加层和/或散热层的厚度进行修剪。该可能的实现方式提高了SAW滤波器的产品良率和性能。
在一种可能的实现方式中，所述在所述温度补偿层背对所述第一基底的表面上形成声速增加层和/或散热层之后，还包括：对所述声速增加层和/或散热层进行退火处理，以消除层内应力。
在一种可能的实现方式中，所述对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来之后，还包括：在所述压电材料层背对所述第一基底的表面上形成封装保护层。该封装保护层能够防止水汽或外界环境对SAW滤波器内部结构的影响，提高SAW滤波器的可靠性。
在一种可能的实现方式中，在所述第一焊垫和所述第二焊垫键合之前，还包括：在第一基底的形成有第一焊垫的表面上形成缓冲层。该缓冲层可以缓解叉指换能器与基底之间的应力，防止其间因应力过大导致压电材料层和叉指换能器的损伤。
在一种可能的实现方式中，形成温度补偿层之后，还包括：在所述温度补偿层背对所述第一基底的表面上形成第三焊垫，所述第三焊垫与所述第二焊垫连接。
在一种可能的实现方式中，形成第三焊垫之后，还包括：在所述第三焊垫背对所述第一基底的表面上形成有金属焊球，所述金属焊球用于与外部电路的电连接。
本申请的第三方面提供了一种射频前端芯片，包括声表面波滤波器、低噪声放大器、功率放大器和数据传输接口；其中，所述声表面波滤波器为上述第一方面及其可能的任一实现方式中所述的声表面波滤波器，所述低噪声放大器、功率放大器和数据传输接口位于空腔内部，且位于所述基底朝向所述压电材料层的表面上。
因本申请第三方面提供的射频前端芯片中包括本申请第一方面及其可能的任一实现方式中所述的声表面波滤波器，相应地，该射频前端芯片具有上述本申请第一方面及其可能的任一实现方式中所述的声表面波滤波器的有益效果。
本申请的第四方面提供了一种移动终端，包括：通信模块，所述通信模块内包括声表面波滤波器，所述声表面波滤波器为上述第一方面及其可能的任一实现方式中所述的声表面波滤波器。
因本申请第四方面提供的移动终端中包括本申请第一方面及其可能的任一实现方式中所述的声表面波滤波器，相应地，该移动终端具有上述本申请第一方面及其可能的任一实现方式中所述的声表面波滤波器的有益效果。
相较于现有技术，本申请具有以下有益效果：
基于以上技术方案可知，本申请提供的声表面波滤波器包括相对设置的基底和压电材料层，其中，基底和压电材料层之间设置有空腔；压电材料层朝向基底的表面上设置有叉指换能器；叉指换能器位于所述空腔内。该空腔内部可以为真空环境，也可以为气体环境。而声波在真空中不能传播，且相较于固体介质，声波在气体介质中的传播能力较低，因而，相较于现有技术，由于空腔的存在，本申请提供的声表面滤波器降低了声波能量从基底泄露出去的能力。而且，声表面波滤波器的杂散模式的声波是由于泄露的声波能量导致的，所以，泄露能力被降低的声波能量减少了声表面波滤波器的杂散模式的声波的存在，从而使得较多的声波能量能够通过期望的传输路径(表面传输路径)进行传输，从而提高了SAW滤波器的Q值和插入损耗。
为了清楚地理解本申请的具体实施方式，下面将描述本申请具体实施方式时用到的附图做一简要说明。
图1是本申请实施例提供的一种SAW滤波器结构示意图；
图2是本申请实施例提供的叉指换能器结构示意图；
图3是本申请实施例提供的另一种SAW滤波器结构示意图；
图4是本申请实施例提供的又一种SAW滤波器结构示意图；
图5是本申请实施例提供的又一种SAW滤波器结构示意图；
图6是本申请实施例提供的又一种SAW滤波器结构示意图；
图7是本申请实施例提供的一种SAW滤波器制造方法流程示意图；
图8(1)至图8(7)是本申请实施例提供的一种SAW滤波器制造方法的一系列制程对应的结构示意图；
图9是本申请实施例提供的另一种SAW滤波器制造方法流程示意图；
图10(1)至图10(4)是本申请实施例提供的另一种SAW滤波器制造方法的一系列制程对应的结构示意图；
图11是本申请实施例提供的射频前端芯片结构示意图；
图12是本申请实施例提供的移动终端结构示意图。
为了解决背景技术部分所述的SAW滤波器存在的声波能量从基底泄露的问题，进而导致SAW滤波器的品质因子和插入损耗偏低的问题，本申请基于声波在真空或空气介质中的传播能力较低的特点提供了一种SAW滤波器。该SAW滤波器包括相对设置的基底和压电材料层，所述基底和所述压电材料层之间设置有空腔；所述空腔的侧壁上设置有用于键合所述基底和所述压电材料层的焊垫；所述压电材料层朝向所述基底的表面上设置有叉指换能器；所述叉指换能器位于所述空腔内。而该空腔内部可以为真空环境，也可以为气体环境。而声波在真空中不能传播，且相较于固体介质，声波在气体介质中的传播能力较低，因而，相较于现有技术，由于空腔的存在，本申请提供的声表面滤波器降低了声波能量从基底泄露出去的能力。而且，声表面波滤波器的杂散模式的声波是由于泄露的声波能量导致的，所以，泄露能力被降低的声波能量减少了声表面波滤波器的杂散模式的声波的存在，从而使得较多的声波能量能够通过期望的传输路径(表面传输路径)进行传输，从而提高了SAW滤波器的Q值和插入损耗。
为使本申请解决的技术问题、技术方案和技术效果更加清楚、完整，下面结合附图对本申请的具体实施方式进行详细描述。
请参见图1，本申请实施例提供的一种SAW滤波器包括：
相对设置的基底10和压电材料层20，基底10和压电材料层20之间设置有空腔30；
基底10朝向压电材料层20的表面上设置有第一焊垫101；第一焊垫101位于空腔30的侧壁上；
压电材料层20朝向基底10的表面上设置有第二焊垫201和叉指换能器202；叉指换能器202位于空腔30内；第二焊垫201位于空腔30的侧壁上；
其中，第一焊垫101和第二焊垫201上下层叠键合在一起。
此外，压电材料层20背对基底10的表面上还可以设置有第三焊垫203，其中，第三焊垫203与第二焊垫201之间电连接。作为一示例，第二焊垫201与第三焊垫203上下相对设置，而且，在第二焊垫201和第三焊垫203相对的压电材料层20区域设置有导电通孔204，通过该导电通孔204实现第三焊垫203与第二焊垫201的电连接。在本申请实施例中，第三焊垫203还可以作为测试焊垫，用于在制造SAW滤波器的过程中，对滤波器的性能进行测试，以根据该测试结果对SAW滤波器的通带频率进行微调，从而提升器件良率。
另外，在第三焊垫203背对压电材料层20的表面上还设置有金属焊垫205，以实现SAW滤波器与外部电路的连接，作为示例，该金属焊垫205可以为金属焊球。
需要说明，在本申请实施例中，空腔为封闭腔体结构，其侧壁可以由闭合的层间介质层或者金属互连层组成，而第一焊垫101可以设置在空腔30的侧壁上。作为示例，该第一焊垫101可以金属凸块，也可以为金属焊球。相应地，第二焊垫201可以金属凸块，也可以为金属焊球。
在上述SAW滤波器的结构中，基底10为支撑基底，其可以为硅基底、玻璃基底或蓝 宝石基底。
作为一示例，根据SAW滤波器结构的设计需要，在基底10朝向压电材料层20的表面上还可以设置有无源器件(图1中未示出)，该无源器件可以与SAW滤波器进行匹配。作为示例，该无源器件可以为电容或电感等器件。
作为一示例，压电材料层20可以通过向压电材料基底表面注入一定深度的离子，然后从注入离子浓度最高的界面处分离下来得到。作为示例，该压电材料基底的材料可以为铌酸锂(LiNbO
3)或钽酸锂(LiTaO
3)。注入的离子类型可以为氢离子，注入的深度可以根据设计的压电材料层的厚度确定。并且根据注入的深度来选择注入能量。
叉指换能器202是在压电材料层20表面上形成形状像两只手的手指交叉状的金属图案，它的作用是实现声一电换能。此外，该叉指换能器202还可以起到滤波作用。作为示例，图2示出了叉指换能器202的俯视图。在本申请实施例中，叉指换能器202使用的金属材料和工艺方法没有特殊限定。作为示例，可以通过剥离工艺(lift-off)完成叉指换能器202的制备。作为另一示例，为了抑制杂散模式，叉指换能器202采用的金属材料可以为Au、Ta、W或Cu等密度较大的金属材料。
作为又一示例，叉指换能器202的厚度可以在1000至
之间。
需要说明，在本申请实施例中，第一焊垫101和第二焊垫201均可以用作键合焊垫。如此，压电材料层20与基底10通过第一焊垫101和第二焊垫201键合在一起，其中，第一焊垫101和第二焊垫201一一对应，当压电材料层20与基底10相对放置时，第一焊垫101和第二焊垫201分别一一对齐，从而通过键合工艺将压电材料层20与基底10键合在一起。
作为一实现方式，第二焊垫201除了用作键合焊垫外，还可以同时用于实现叉指换能器202中的各电极之间的电性连接。作为本申请的另一替换实现方式，受限于键合工艺的限制，用于实现叉指换能器202中的各电极之间的电性连接的焊垫与用作键合的焊垫可以分开。
作为一示例，第一焊垫101可以为通过低压力化学气相沉积法(Low Pressure Chemical Vapor Deposition，LPCVD)生长多晶硅并用刻蚀方法形成的焊垫。作为另一示例，第一焊垫101也可以为通过电镀工艺或者电子束蒸发沉积工艺形成的金属焊垫。
作为另一示例，第二焊垫201可以为通过电镀工艺或者电子束蒸发沉积工艺形成的金属焊垫。该金属焊垫的材料可以为金，厚度可以为2000至
之间。
作为本申请的另一实现方式，为了提高第一焊垫101与第二焊垫201之间的键合力，在第一焊垫101和第二焊垫201之间还可以设置有一层粘附层(图1中未示出)，该粘附层的材料可以为Ti或者Cr。
以上为本申请实施例提供的一种SAW滤波器的具体实现方式。在上述实施例提供的SAW滤波器的具体实现方式中，在基底10和压电材料层20相对的表面上均设置有用于键合基底10和压电材料层20的焊垫。实际上，作为本申请的一扩展实施例，也可以仅在基底10朝向压电材料层20的表面上设置有焊垫，该焊垫可以直接键合在压电材料层20朝向 基底10的表面上。作为本申请的另一扩展实施例，也可以仅在压电材料层20朝向基底10的表面上设置有焊垫，该焊垫直接键合在基底10朝向压电材料层20的表面上。
在上述本申请实施例提供的SAW滤波器的具体实现方式中，基底10与压电材料层20相对设置，空腔30位于基底10和压电材料层20之间；并且将设置于压电材料层20表面上的叉指换能器202位于空腔30内。而该空腔内部可以为真空环境，也可以为气体环境。而声波在真空中不能传播，且相较于固体介质，声波在气体介质中的传播能力较低，因而，相较于现有技术，由于空腔的存在，本申请提供的声表面滤波器降低了声波能量从基底泄露出去的能力。而且，声表面波滤波器的杂散模式的声波是由于泄露的声波能量导致的，所以，泄露能力被降低的声波能量减少了声表面波滤波器的杂散模式的声波的存在，从而使得较多的声波能量能够通过期望的传输路径(表面传输路径)进行传输，从而提高了SAW滤波器的Q值和插入损耗。
在上述图1所示的实施例中，叉指换能器202不与基底10接触，两者之间存在一定的间隙，如此可以减少声波能量从基底10侧泄露的可能。
作为本申请的另一实施例，如图3所示，叉指换能器202与基底10接触，如此可以增加空腔30的机械支撑力，提高SAW滤波器的结构稳定性。
需要说明，在本申请实施例中，可以通过调整叉指换能器202、第一焊垫101和第二焊垫201的高度来实现叉指换能器202与基底10接触与否。具体地，当叉指换能器202的高度等于第一焊垫101和第二焊垫201的高度之和时，可以实现叉指换能器202与基底10接触。当叉指换能器202的高度小于第一焊垫101和第二焊垫201的高度之和时，可以实现叉指换能器202不与基底10接触。
另外，作为本申请的一实现方式，在图3所示的SAW滤波器中，可以在基底10朝向压电材料层20的表面上设置有缓冲层(图3中未示出)，该缓冲层可以缓解叉指换能器202与基底10之间的应力，防止其间因应力过大导致压电材料层20和叉指换能器202的损伤。
作为一示例，该缓冲层的材料可以在基底10与压电材料层20键合工艺过程中能够变软，从而保证叉指换能器202与缓冲层之间的充分结合，同时保留基底10与压电材料层20之间的空腔。作为一具体示例，该缓冲层可以由树脂材料制成。
需要说明，用于制成压电材料层20的传统压电材料例如铌酸锂或钽酸锂的负温度系数特性，导致SAW滤波器的通带频率随温度变化发生漂移的问题较为严重。为了缓解SAW滤波器的通带频率随温度变化发生漂移的问题，本申请还提供了SAW滤波器的又一实施例。
请参见图4，该SAW滤波器除了包括图1所示的各个结构外，还可以包括温度补偿层206，该温度补偿层206位于压电材料层20背对基底10表面上。
需要说明，在图4中，第三焊垫203位于温度补偿层206背对基底10的表面上，导电通孔204除了贯穿压电材料层20以外，还上下贯穿温度补偿层206。
当压电材料层20具有负温度系数特性时，该温度补偿层206具有正温度系数特性，可以在一定程度上缓解SAW滤波器的通带频率随温度变化发生漂移的问题。作为示例，该温度补偿层206的材料可以为二氧化硅。
需要说明，因压电材料层20背对基底10的表面为完全平整平面，所以用于形成温度补偿层206的沉积工艺可以有很多选择，作为示例，可以选用等离子体增强化学的气相沉积(Plasma Enhanced Chemical Vapor Deposition PECVD)、LPCVD或物理气相沉积(Physical Vapor Deposition，PVD)。
另外，温度补偿层206的厚度和致密性会影响声波的等效声速，厚度太薄或者致密性太差，则会出现温度补偿效果不明显的问题，若温度太厚的话，则需要制备密度较大的叉指换能器电极，导致制备工艺较为复杂。因此，作为示例，该温度补偿层206的厚度可以在
之间，以兼顾上述各个问题。
需要说明，图4所示的SAW滤波器是在图1所示的基础上进行改进得到的，实际上，作为本申请实施例的扩展，设置有温度补偿层的SAW滤波器也可以在图3所示的SAW滤波器的基础上进行改进得到。
在上述各个实施例所示的SAW滤波器结构中，能够减少声波能量在基底10侧的泄露，从而提高了该SAW滤波器的Q值和插入损耗。为了进一步减少声波能量的泄露，进而进一步提高SAW滤波器的Q值和插入损耗，本申请还提供了SAW滤波器的又一实施例，以减少声波能量在压电材料层一侧的泄露，从而进一步提高SAW滤波器的Q值和插入损耗。
请参见图5，本申请实施例提供的SAW滤波器除了包括图4所示的各个结构外，还可以包括声速增加层207，该声速增加层207位于温度补偿层206背对基底10的表面上。该声速增加层207可以提高声表面波的等效声速。
作为一示例，声速增加层207可以仅设置在温度补偿层206背对叉指换能器202的表面区域上，而非覆盖温度补偿层206的整个表面。
作为另一示例，声速增加层207也可以覆盖温度补偿层206的整个表面。
作为示例，该声速增加层207的材料可以为高声阻材料，例如可以为AlN、Al
2O
3、SiC、SiN、SiON等。该声速增加层207的厚度可以为
在图5所示的SAW滤波器中，一方面，声波能量不容易通过空腔30从基底10侧泄露。另一方面，设置在压电材料层20背对基底10表面上的温度补偿层206和声速增加层207可以将声波能量限制在温度补偿层206和声速增加层207之间，如此，声波能量不容易从压电材料层20侧泄露。因此，图5所示的SAW滤波器，声波能量不仅不能从基底侧泄露出去，也不能从压电材料层一侧泄露出去，因此，该SAW滤波器进一步减少声波能量的泄露，进而进一步提高SAW滤波器的Q值和插入损耗。
另外，作为本申请的另一实现方式，为了提高器件的散热性能，上述图5所示的声速增加层207可以替换为散热层，该散热层可以由高导热系数材料制成。作为示例，该高导热系数材料可以为AlN、A
l2O
3、SiC、SiN、SiON等。该散热层的厚度可以为
此外，因用于制备声速增加层207的高声阻材料与用于制备散热层的散热材料可以为同一种材料，因此，声速增加层207与散热层可以为同一层结构。
另外，当用于制备声速增加层207的高声阻材料与用于制备散热层的散热材料为不同种材料时，作为本申请的另一实现方式，可以在温度补偿层206背对基底10的表面上同时 形成层叠设置的声速增加层和散热层。其中，在申请实施例中，对声速增加层和散热层的上下位置关系不做限定。
此外，为了防止水汽或外界环境对SAW滤波器内部结构的影响，提高SAW滤波器的可靠性，本申请还提供了SAW滤波器的又一种实现方式。
请参见图6，本申请实施例提供的SAW滤波器除了包括图5所示的各个结构以外，还可以包括：
封装保护层208，该封装保护层208覆盖声速增加层207以及未被声速增加层207覆盖的温度补偿层206背对基底10的表面。
一方面，该封装保护层208可以防止封装工艺过程对SAW内部结构的破坏，另一方面，该封装保护层208可以隔绝外界水汽等外界环境对SAW内部结构的影响，从而提高了器件的可靠性。另外，该封装保护层208还可以增加薄膜压电结构的机械强度，抑制兰姆波(lamb wave)模式的发生。
作为示例，该封装保护层208的材料可以选自聚对苯撑苯并二噁唑纤维(Poly-p-phenylene benzobisoxazole，PBO)或者聚酰亚胺(polymide，PI)中的至少一种。
另外，在图6所示的SAW滤波器中，由于声速增加层207的存在，在一定程度上避免了声波从封装保护层208的泄露。
需要说明，在图6所示的SAW滤波器中，第三焊垫203位于封装保护层208背对基底10的表面上，导电通孔204除了贯穿压电材料层20和温度补偿层206以外，还上下贯穿封装保护层208。
以上为本申请实施例提供的SAW滤波器的多个具体实现方式。在该多个具体实现方式中，其内部的电信号可以通过第一焊垫101、第二焊垫201以及第三焊垫203以及设置在压电材料层20一侧的金属焊球与外部电路实现电连接。实际上，在本申请的多个具体实现方式中，其封装形式可以更加灵活。作为本申请的另一可选实现方式，也可以在基底10上设置有导电柱塞，SAW滤波器内部的电信号可以通过第一焊垫101、第二焊垫201以及第三焊垫203和导电柱塞引出，从而与外部电路实现电连接。
另外，在该多个具体实现方式中，相互之间可以相互组合，且组合后的SAW滤波器的结构均在本申请的保护范围之列。
基于上述实施例提供的SAW滤波器的多个具体实现方式，相应地，本申请还提供了SAW滤波器的制造方法的具体实现方式。
请参见图7至图8(7)，本申请实施例提供的一种SAW滤波器的制造方法包括：
S701：在第一基底的一表面上形成第一焊垫。
作为示例，可以采用LPCVD工艺在第一基底10的一表面上生长一层导电层，然后，通过刻蚀方法在第一基底10的一表面上形成第一焊垫101。
作为示例，该导电层的材料可以为多晶硅，也可以为导电金属。第一基底10为支撑基底，其可以为硅基底、玻璃基底或蓝宝石基底。
该步骤执行完对应的剖面结构示意图如图8(1)所示。
作为另一示例，根据待制造的SAW滤波器的需要，还可以在第一基底的至少一个表面上形成无源器件(图8(1)中未示出)，该无源器件可以用于与SAW滤波器进行匹配。作为示例，该无源器件可以为电容或电感等器件。
S702：在第二基底的第一表面进行离子注入，以在靠近所述第二基底的第一表面侧形成压电材料层。
本步骤可以具体为：根据设计的压电材料层的厚度，获取离子注入的能量，根据该获取到的离子注入能量，从第二基底20’的第一表面向第二基底20’内部进行离子注入，从而在靠近第二基底20’的第一表面一侧形成压电材料层20。作为示例，该注入的能量可以为100-150KeV，注入的离子剂量可以为3*10e16～8*10e16atoms/cm
2。
第二基底20’可以为压电材料基底，例如为铌酸锂基底或钽酸锂基底。
该步骤执行完对应的剖面结构示意图如图8(2)所示。
图8(2)中，虚线代表离子浓度最高的位置。当后续经过高温处理时，第二基底20’会在该虚线处产生微气泡，从而使得压电材料层20从第二基底20’上分离下来。
S703：在所述压电材料层上形成第二焊垫和叉指换能器；其中，当所述第一基底与所述第二基底层叠放置且所述第一基底的形成有第一焊垫表面朝向所述压电材料层时，所述第一焊垫与所述第二焊垫一一相互对应。
本步骤可以具体为：通过图形化工艺在压电材料层20的表面上形成第二焊垫201和叉指换能器202。
在本申请实施例中，叉指换能器202使用的金属材料和工艺方法没有特殊限定、作为示例，可以通过剥离工艺(lift-off)完成叉指换能器202的制备。作为另一示例，为了抑制杂散模式，叉指换能器202采用的金属材料可以为Au、Ta、W或Cu等密度较大的金属材料。作为又一示例，叉指换能器202的厚度可以在1000至
之间。
作为更具体示例，第二焊垫201可以采用电镀工艺或者电子束蒸发沉积工艺形成。第二焊垫的厚度可以为2000至
之间。
该步骤执行完对应的剖面结构示意图如图8(3)所示。
S704：将一一相互对应的所述第一焊垫和所述第二焊垫键合在一起，从而使所述叉指换能器位于所述第一焊垫和所述第二焊垫围成的空腔内。
本步骤可以具体为：按照第一基底10上形成有第一焊垫101的表面朝向第二基底20’上的压电材料层的方式相对放置第一基底10和第二基底20’，并且使得相互对应的第一焊垫101和第二焊垫201一一对准，然后，采用键合工艺将一一相互对应的第一焊垫101和第二焊垫201键合在一起，从而在第一基底10和第二基底20’之间形成空腔30。其中，第一焊垫101和第二焊垫201形成空腔30的侧壁，并且使叉指换能器202位于空腔30内。
作为示例，本步骤采用的键合工艺可以为共晶键合工艺。作为更具体示例，键合温度可以为300-400℃，时间保持30-60min。
该步骤执行完对应的剖面结构示意图如图8(4)所示。
S705：对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来。
本步骤可以具体为：对S704形成的结构在250至400℃进行热处理，在该热处理过程中，第二基底20’会从注入离子浓度最高的位置产生微气泡，在施加应力后，压电材料层20从第二基底20’上分离下来。
该步骤执行完对应的剖面结构示意图如图8(5)所示。
S706：对压电材料层进行热处理，以提高压电材料层的压电特性。
需要说明，注入的离子会对第二基底20’的压电性能造成一定的破坏，因此，为了提高SAW滤波器的性能，本申请实施例可以通过对压电材料层进行热处理，从而提高压电材料层的压电特性。
作为示例，本步骤采用的热处理的温度范围在300-600℃之间，更具体地，该热处理的温度范围在400至500℃之间，持续时间为2-4小时。
S707：在与第二焊垫相对的压电材料层区域形成通孔。
本步骤可以具体为：采用刻蚀工艺在与第二焊垫201相对的压电材料层20的区域上形成通孔204’。
该步骤执行完对应的剖面结构示意图如图8(6)所示。
S708：在通孔的上方形成第三焊垫。
作为示例，本步骤可以具体为：首先，在压电材料层20背对第一基底10的表面上形成一层导电材料层，其中，在形成导电材料层的同时，导电材料会填充到通孔204’内，从而使通孔204’形成导电通孔204。
然后，采用图形化工艺刻蚀导电材料层，从而在通孔204’的上方形成第三焊垫203。该步骤执行完对应的剖面结构示意图如图8(7)所示。
S709：在第三焊垫背对压电材料层的表面上形成与外部电路电连接的金属焊球。
该步骤执行完对应的剖面结构示意图如图1所示。
以上为本申请实施例提供的一种SAW滤波器的具体实现方式。
需要说明，在本申请实施例提供的SAW滤波器的具体实现方式中，可以形成图1或图3所示的SAW滤波器。其中，叉指换能器202与基底10接触与否可以通过调整叉指换能器202、第一焊垫101和第二焊垫201的高度来实现。当叉指换能器202的高度小于第一焊垫101和第二焊垫201的高度之和时，可以实现叉指换能器202不与基底10接触，从而形成图1所示的结构。当叉指换能器202的高度等于第一焊垫101和第二焊垫201的高度之和时，可以实现叉指换能器202与基底10接触，从而形成图3所示的结构。
另外，当形成图3所示的SAW滤波器结构时，为了缓解叉指换能器202与基底10之间的应力，防止其间因应力过大导致压电材料层20和叉指换能器202的损伤，在S704之前，还可以包括以下步骤：
在第一基底10形成有第一焊垫的表面上形成缓冲层。
该缓冲层的材料可以在基底10与压电材料层20键合工艺过程中变软，从而保证叉指换能器202与缓冲层之间的充分结合，同时保留基底10与压电材料层20之间的空腔。作为一具体示例，该缓冲层可以由树脂材料制成。
在上述实施例提供的SAW滤波器的制造方法中，可以将叉指换能器202置于空腔30内，而该空腔内部可以为真空环境，也可以为气体环境。而声波在真空中不能传播，且相较于固体介质，声波在气体介质中的传播能力较低，所以，声波能量不容易通过空腔30从基底10侧泄露出去，因而，形成于基底10和压电材料层20之间的空腔30可以减少杂散模式的声波的存在，降低了声波能量从基底10泄露的可能，从而提高了SAW滤波器的Q值和插入损耗。
需要说明，用于制成压电材料层20的传统压电材料例如铌酸锂或钽酸锂的负温度系数特性，导致SAW滤波器的通带频率随温度变化发生漂移的问题较为严重。为了缓解SAW滤波器的通带频率随温度变化发生漂移的问题，本申请还提供了另一种SAW滤波器制造方法。
请参见图9至图10(4)，本申请提供的另一种SAW滤波器制造方法包括以下步骤：
S901至S906与上述S701至S706相同，为了简要起见，在此不再详细描述。
S907：在压电材料层背对第一基底的表面上形成温度补偿层。
需要说明，因压电材料层20背对基底10的表面为完全平整平面，所以，本步骤可以采用常规的薄膜沉积工艺在在压电材料层20背对第一基底10的表面上形成温度补偿层206。
用于形成温度补偿层206的沉积工艺可以有很多选择，作为示例，可以选用PECVD、LPCVD或PVD。
当压电材料层20具有负温度系数特性时，该温度补偿层206具有正温度系数特性，可以在一定程度上缓解SAW滤波器的通带频率随温度变化发生漂移的问题。作为示例，该温度补偿层206的材料可以为二氧化硅。
另外，温度补偿层206的厚度和致密性会影响声波的等效声速，厚度太薄或者致密性太差，则会出现温度补偿效果不明显的问题，若温度太厚的话，则需要制备密度较大的叉指换能器电极，导致制备工艺较为复杂。因此，作为示例，该温度补偿层206的厚度可以在
之间，以兼顾上述各个问题。
该步骤执行完对应的剖面结构示意图如图10(1)所示。
作为本申请的另一可选实施例，为了实现对SAW滤波器的通带频率的调节，在S907之后，还可以包括以下步骤：
S908：根据设计需要，对所述温度补偿层的厚度进行修剪。
本步骤可以具体为：在形成温度补偿层206之后，对SAW滤波器的性能进行测试，并比较SAW滤波器设计的目标性能与测试得到的实际性能，若测试到的实际性能与目标性能不一致，则可以利用粒子研磨工艺对第一基底不同区域上的温度补偿层的厚度进行差异化修剪，从而使不同区域SAW滤波器的通带频率一致，进而实现对SAW滤波器的通带频率的调节，进而提高SAW滤波器的均一性和产品良率。
作为本申请的又一可选实现方式，为了进一步减少声波能量的泄露，进而进一步提高SAW滤波器的Q值和插入损耗，在上述可选实现方式的基础上，还可以在S908之后，包括以下步骤：
S909：在温度补偿层背对第一基底的表面上形成声速增加层。
作为一种实现方式，本步骤可以采用PECVD工艺在温度补偿层206背对第一基底10的表面上形成声速增加层207，该声速增加层207可以提高声表面波的等效声速。
作为一示例，声速增加层207可以仅设置在温度补偿层206的背对叉指换能器202的表面区域上，而非覆盖整个温度补偿层206的表面。
另外，当声速增加层207由高导热系数材料制成时，声速增加层207还可以作为散热层，从而提高SAW滤波器的散热性能。
作为示例，该声速增加层207的材料可以为高声阻材料，例如可以为AlN、Al
2O
3、SiC、SiN、SiON等。该声速增加层207的厚度可以为
该步骤执行完对应的剖面结构示意图如图10(2)所示。
作为另一种实现方式，为了提高SAW滤波器的散热性，S909可以替换为：在温度补偿层背对第一基底的表面上形成散热层。
此外，因用于制备声速增加层207的高声阻材料与用于制备散热层的散热材料可以为同一种材料，因此，声速增加层207与散热层可以为同一层结构。
另外，当用于制备声速增加层207的高声阻材料与用于制备散热层的散热材料为不同种材料时，为了使得制备出的SAW滤波器既能够减少声波能量在压电材料层侧的泄露，又能够提高SAW滤波器的散热性能，作为本申请的另一实现方式，可以在温度补偿层206背对基底10的表面上同时形成层叠设置的声速增加层和散热层。其中，在申请实施例中，对声速增加层和散热层的上下位置关系不做限定。
S910：根据设计需要，对声速增加层的厚度进行修剪。
本步骤可以具体为：在形成声速增加层207之后，对SAW滤波器的性能进行测试，并比较SAW滤波器设计的目标性能与测试得到的实际性能，若测试到的实际性能与目标性能不一致，则可以利用粒子研磨工艺对第一基底不同区域上的声速增加层207的厚度进行第一基底不同区域上的修剪，从而使不同区域SAW滤波器的通带频率一致，进而实现对SAW滤波器的通带频率的调节，进而提高SAW滤波器的均一性和产品良率。
作为本申请的又一可选实现方式，为了防止水汽或外界环境对SAW滤波器内部结构的影响，提高SAW滤波器的可靠性，在上述可选实现方式的基础上，在S910之后，还可以包括：
S911：在声速增加层207以及未被声速增加层207覆盖的温度补偿层206背对基底10的表面形成封装保护层208。
一方面，该封装保护层208可以防止封装工艺过程对SAW内部结构的破坏，另一方面，该封装保护层208可以隔绝外界水汽等外界环境对SAW内部结构的影响，从而提高了器件的可靠性。另外，该封装保护层208还可以增加薄膜压电结构的机械强度，抑制兰姆波(lamb wave)模式的发生。
作为示例，该封装保护层208的材料可以选自PBO或者PI中的至少一种。
该步骤执行完对应的剖面结构示意图如图10(3)所示。
S912：刻蚀封装保护层、温度补偿层和压电材料层，以形成通孔。
本步骤可以具体为：在第二焊垫201的上方刻蚀封装保护层208、温度补偿层206和压电材料层20，以形成贯穿封装保护层208、温度补偿层206和压电材料层20的通孔204’。该通孔204’与第二焊垫201连通。
该步骤执行完对应的剖面结构示意图如图10(4)所示。
S913至S914与S708至S709相同，为了简要起见，在此不再详细描述。最终形成图6所示的SAW滤波器结构。
需要说明，在本申请实施例中，第三焊垫203可以用作测试焊垫，利用该第三焊垫203可以对SAW滤波器的性能进行测试，得到SAW滤波器性能的测试结果。
以上为本申请实施例提供的另一种SAW滤波器制造方法的具体实现方式。该制造方法的具体实现方式除了具有上述实施例提供的制造方法的有益效果外，还具有以下效果：
1、因压电材料层20背对第一基底10的表面为平整表面，所以，用于形成温度补偿层206的工艺有较多选择，而且，形成温度补偿层206的工艺难度较小，无需在形成温度补偿层206之后，进行磨平工序，从而减少了化学机械研磨工艺，简化了工艺流程，降低了制造成本。
2、因声表面波的等效声速与设置在压电材料层20背对叉指换能器表面上的温度补偿层206、声速增加层207、散热层的厚度相关，而在本申请实施例提供的SAW滤波器的制造方法中，可以在形成温度补偿层206、声速增加层207或散热层之后，可以插入修剪工艺分别对各层厚度进行修剪，从而提高了SAW滤波器的产品良率和性能。
在上述提供的SAW滤波器的制造方法的两种实现方式中，其内部的电信号可以通过第一焊垫101、第二焊垫201以及第三焊垫203以及设置在压电材料层20一侧的金属焊球与外部电路实现电连接。实际上，在本申请的多个具体实现方式中，其封装形式可以更加灵活。作为本申请的另一可选实现方式，也可以在第一基底10上设置有导电柱塞，SAW滤波器内部的电信号可以通过第一焊垫101、第二焊垫201以及第三焊垫203和导电柱塞从第一基底10背对压电材料层20的一侧引出，从而与外部电路实现电连接。
在上述SAW滤波器的制造方法中，在第一基底10和第二基底20’的表面上均形成有用于键合的焊垫。实际上，作为本申请的一扩展实施例，可以仅在第一基底10形成焊垫，利用该焊垫直接焊接在第二基底20’的表面上。作为本申请的另一扩展实施例，也可以尽在第二基底20’的表面上形成焊垫，利用该焊垫直接焊接在第一基底10的表面上。
以上为本申请实施例提供的SAW滤波器及其制造方法的具体实现方式。
基于上述实施例提供的SAW滤波器，本申请还提供了一种射频前端芯片。如图11所示，该射频前端芯片包括声表面波滤波器111、低噪声放大器112、功率放大器113和数据 传输接口114；
其中，所述声表面波滤波器为上述任一实施例所述的声表面波滤波器。作为示例，图11所示的声表面波滤波器为上述图1所示的声表面波滤波器。
其中，低噪声放大器112、功率放大器113和数据传输接口114位于空腔30内部，且位于基底10朝向压电材料层20的表面上。
本申请还提供了一种移动终端的具体实现方式。
请参见图12，本申请实施例提供的移动终端包括通信模块121，该通信模块121内包括声表面波滤波器1211，该声表面波滤波器1211可以为上述任一实现方式提供的声表面波滤波器。
作为示例，本申请实施例所述的移动终端可以为手机、平板电脑等等。
以上为本申请实施例提供的具体实现方式。
Claims (22)
- 一种声表面波滤波器，其特征在于，包括：相对设置的基底和压电材料层，所述基底和所述压电材料层之间设置有空腔；所述空腔的侧壁上设置有用于键合所述基底和所述压电材料层的焊垫；所述压电材料层朝向所述基底的表面上设置有叉指换能器；所述叉指换能器位于所述空腔内。
- 根据权利要求1所述的滤波器，其特征在于，所述焊垫包括位于所述基底朝向所述压电材料层表面上的第一焊垫，和/或，位于所述压电材料层朝向所述基底表面上的第二焊垫；所述第一焊垫和所述第二焊垫层叠设置。
- 根据权利要求1所述的滤波器，其特征在于，所述滤波器还包括：温度补偿层，所述温度补偿层位于所述压电材料层背对所述基底的表面上。
- 根据权利要求3所述的滤波器，其特征在于，所述滤波器还包括：声速增加层，所述声速增加层至少覆盖所述温度补偿层背对所述叉指换能器的表面区域。
- 根据权利要求3所述的滤波器，其特征在于，所述滤波器还包括：散热层，所述散热层至少覆盖所述温度补偿层背对所述叉指换能器的表面区域。
- 根据权利要求4所述的滤波器，其特征在于，所述滤波器还包括：封装保护层，所述封装保护层覆盖所述声速增加层以及未被所述声速增加层覆盖的温度补偿层背对所述基底的表面上。
- 根据权利要求5所述的滤波器，其特征在于，所述滤波器还包括：封装保护层，所述封装保护层覆盖所述散热层以及未被所述散热层覆盖的温度补偿层背对所述基底的表面上。
- 根据权利要求1-7任一项所述的滤波器，其特征在于，所述叉指换能器与所述基底接触。
- 根据权利要求8所述的滤波器，其特征在于，所述基底朝向所述压电材料层的表面上设置有缓冲层。
- 根据权利要求3-7任一项所述的滤波器，其特征在于，所述温度补偿层的厚度在1000至之间。
- 一种声表面波滤波器的制造方法，其特征在于，包括：在第一基底的一表面上形成第一焊垫；在第二基底的第一表面进行离子注入，以在靠近所述第二基底的第一表面一侧形成压电材料层；在所述压电材料层上形成第二焊垫和叉指换能器；其中，当所述第一基底与所述第二基底层叠放置且所述第一基底的形成有第一焊垫表面朝向所述压电材料层时，所述第一焊垫与所述第二焊垫一一相互对应；将一一相互对应的所述第一焊垫和所述第二焊垫键合在一起，从而使所述叉指换能器位于所述第一焊垫和所述第二焊垫围成的空腔内；对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来。
- 根据权利要求11所述的方法，其特征在于，所述对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来之后，还包括：对所述压电材料层进行热处理，以提高所述压电材料层的压电特性。
- 根据权利要求11所述的方法，其特征在于，所述对所述压电材料层进行热处理，具体包括：在400至500℃的温度范围内对所述压电材料层进行热处理。
- 根据权利要求11所述的方法，其特征在于，所述对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来之后，还包括：在所述压电材料层背对所述第一基底的表面上形成温度补偿层。
- 根据权利要求14所述的方法，其特征在于，所述在所述压电材料层背对所述第一基底的表面上形成温度补偿层之后，还包括：根据设计需要，对所述温度补偿层的厚度进行修剪。
- 根据权利要求14所述的方法，其特征在于，在所述压电材料层背对所述第一基底的表面上形成温度补偿层之后，还包括：在所述温度补偿层背对所述第一基底的表面上形成声速增加层或散热层，所述声速增加层或散热层仅覆盖所述温度补偿层背对所述基底的部分表面区域。
- 根据权利要求16所述的方法，其特征在于，所述在所述温度补偿层背对所述第一基底的表面上形成声速增加层或散热层之后，还包括：根据设计需要，对所述声速增加层和/或散热层的厚度进行修剪。
- 根据权利要求16或17所述的方法，其特征在于，所述在所述温度补偿层背对所述第一基底的表面上形成声速增加层和/或散热层之后，还包括：对所述声速增加层和/或散热层进行退火处理，以消除层内应力。
- 根据权利要求11所述的方法，其特征在于，所述对所述第二基底进行热处理，以使所述压电材料层从所述第二基底上分离下来之后，还包括：在所述压电材料层背对所述第一基底的表面上形成封装保护层。
- 根据权利要求11-19任一项所述的方法，其特征在于，在所述第一焊垫和所述第二焊垫键合之前，还包括：在第一基底的形成有第一焊垫的表面上形成缓冲层。
- 一种射频前端芯片，其特征在于，包括声表面波滤波器、低噪声放大器、功率放大器和数据传输接口；其中，所述声表面波滤波器为权利要求1-10任一项所述的声表面波滤波器，所述低噪声放大器、功率放大器和数据传输接口位于空腔内部，且位于所述基底朝向所述压电材料层的表面上。
- 一种移动终端，其特征在于，包括：通信模块，所述通信模块内包括声表面波滤波器，所述声表面波滤波器为权利要求1-10任一项所述的声表面波滤波器。
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