CN111510093B - Piezoelectric film body for manufacturing bulk acoustic wave device and preparation method thereof - Google Patents
Piezoelectric film body for manufacturing bulk acoustic wave device and preparation method thereof Download PDFInfo
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- CN111510093B CN111510093B CN202010341765.7A CN202010341765A CN111510093B CN 111510093 B CN111510093 B CN 111510093B CN 202010341765 A CN202010341765 A CN 202010341765A CN 111510093 B CN111510093 B CN 111510093B
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 51
- 238000002360 preparation method Methods 0.000 title abstract description 9
- 239000010408 film Substances 0.000 claims abstract description 197
- 238000005728 strengthening Methods 0.000 claims abstract description 103
- 238000000034 method Methods 0.000 claims abstract description 50
- 239000010409 thin film Substances 0.000 claims abstract description 40
- 239000000758 substrate Substances 0.000 claims abstract description 37
- 239000000463 material Substances 0.000 claims description 25
- 230000003014 reinforcing effect Effects 0.000 claims description 16
- 238000002955 isolation Methods 0.000 claims description 15
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 12
- 238000000151 deposition Methods 0.000 claims description 11
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 10
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 10
- 230000008021 deposition Effects 0.000 claims description 10
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical group O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 10
- 238000005468 ion implantation Methods 0.000 claims description 9
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims description 7
- 238000005498 polishing Methods 0.000 claims description 7
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims description 5
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 5
- 235000012239 silicon dioxide Nutrition 0.000 claims description 5
- 239000000377 silicon dioxide Substances 0.000 claims description 5
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 abstract description 15
- 239000002184 metal Substances 0.000 abstract description 15
- 238000005530 etching Methods 0.000 abstract description 13
- 230000007547 defect Effects 0.000 abstract description 8
- 238000010586 diagram Methods 0.000 description 8
- 238000000926 separation method Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 4
- 239000001307 helium Substances 0.000 description 4
- 229910052734 helium Inorganic materials 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000000231 atomic layer deposition Methods 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- -1 helium ions Chemical class 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 238000002207 thermal evaporation Methods 0.000 description 2
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 230000008093 supporting effect Effects 0.000 description 1
Classifications
-
- 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
- H03H3/08—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 resonators or networks using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
Abstract
The application discloses a piezoelectric film body for manufacturing a bulk acoustic wave device and a preparation method thereof, wherein the piezoelectric film body for manufacturing the bulk acoustic wave device comprises a film body substrate, a first strengthening layer, a piezoelectric film layer and a second strengthening layer which are sequentially overlapped; wherein the Young's moduli of the first strengthening layer and the second strengthening layer are greater than the Young's modulus of the piezoelectric thin film layer. The problems that the piezoelectric film is in direct contact with the metal electrode, is easy to overstock in the back etching process, is easy to crack in the device manufacturing process and the like can be solved; meanwhile, the preparation method can solve the problems that lattice mismatch, thermal mismatch and interface defects are easy to generate in the existing piezoelectric film forming method.
Description
Technical Field
The application relates to the technical field of piezoelectric films, in particular to a piezoelectric film body for manufacturing a bulk acoustic wave device and a preparation method thereof.
Background
With the development of piezoelectric thin film technology, piezoelectric thin films are increasingly applied to the manufacture of bulk acoustic wave devices. At present, the film structure of the piezoelectric film body is usually an oxide-piezoelectric film layer, and the film structure of a bulk acoustic wave device manufactured by adopting the piezoelectric film body is usually a metal-piezoelectric film body-metal.
However, in the fabricated bulk acoustic wave device, the piezoelectric thin film layer is in direct contact with the metal, and higher harmonics are liable to occur, resulting in poor out-of-band suppression effect of the bulk acoustic wave device. When the piezoelectric film body is used for manufacturing the bulk acoustic wave device, the substrate on the back surface needs to be etched, and the etching precision is difficult to control, so that overetching is easy to occur; and because the stress intensity of the piezoelectric film layer is lower, the piezoelectric film layer is easy to crack in the process of manufacturing the device, and the yield of the bulk acoustic wave device is greatly reduced. In addition, the existing film forming method of the piezoelectric film generally adopts pulse laser deposition, magnetron sputtering, atomic layer deposition, thermal evaporation and the like, and the problems of lattice mismatch, thermal mismatch, interface defects and the like are easy to generate.
Disclosure of Invention
The application provides a piezoelectric film body for manufacturing a bulk acoustic wave device, which can solve the problems that a piezoelectric film is in direct contact with a metal electrode, is easy to overstock in the back etching process, is easy to crack in the device manufacturing process and the like; and simultaneously, the preparation method of the piezoelectric film body for manufacturing the bulk acoustic wave device can solve the problems that lattice mismatch, thermal mismatch and interface defects are easy to generate in the existing piezoelectric film forming method.
In one aspect, a piezoelectric film body for fabricating a bulk acoustic wave device includes a film body substrate, a first stiffening layer, a piezoelectric film layer, and a second stiffening layer, which are sequentially stacked;
wherein the Young's moduli of the first strengthening layer and the second strengthening layer are greater than the Young's modulus of the piezoelectric thin film layer.
Optionally, the film body substrate further comprises an isolation layer, wherein the isolation layer is positioned between the film body substrate and the first strengthening layer.
Optionally, the thickness of the first strengthening layer ranges from 2nm to 100nm, and the thickness of the second strengthening layer ranges from 2nm to 100nm;
the thickness of the piezoelectric film layer ranges from 100nm to 3000nm.
Optionally, the material of the film body substrate is monocrystalline silicon or lithium niobate.
Optionally, the materials of the first strengthening layer and the second strengthening layer are aluminum oxide or aluminum nitride;
the piezoelectric film layer is made of lithium niobate or lithium tantalate.
Optionally, the material of the isolation layer is silicon dioxide or silicon nitride.
In another aspect, a method of fabricating a piezoelectric film body for a bulk acoustic wave device includes:
manufacturing a first strengthening layer on a film body substrate;
manufacturing a piezoelectric film layer on the first reinforced layer by an ion implantation bonding method;
and manufacturing a second strengthening layer on the piezoelectric film layer to obtain the piezoelectric film body for manufacturing the bulk acoustic wave device.
Optionally, a method for preparing a piezoelectric film body for making a bulk acoustic wave device further includes:
an isolation layer is fabricated on the film body substrate prior to fabricating the first stiffening layer.
Optionally, the fabricating a first strengthening layer on the film body substrate includes:
manufacturing a first strengthening layer on the film body substrate by means of magnetron sputtering or atomic deposition;
and polishing the first strengthening layer to ensure that the thickness of the first strengthening layer ranges from 2nm to 100nm.
Optionally, the fabricating a second strengthening layer on the piezoelectric film layer to obtain a piezoelectric film body for fabricating a bulk acoustic wave device includes:
manufacturing a second strengthening layer on the piezoelectric film layer by means of magnetron sputtering or atomic deposition;
and polishing the second strengthening layer to ensure that the thickness of the second strengthening layer ranges from 2nm to 100nm, thereby obtaining the piezoelectric film body for manufacturing the bulk acoustic wave device.
According to the technical scheme, the piezoelectric film body for manufacturing the bulk acoustic wave device comprises a film body substrate, a first reinforcing layer, a piezoelectric film layer and a second reinforcing layer which are sequentially overlapped; wherein the Young's moduli of the first strengthening layer and the second strengthening layer are greater than the Young's modulus of the piezoelectric thin film layer.
When the piezoelectric film body for manufacturing the bulk acoustic wave device and the preparation method thereof are used for manufacturing the bulk acoustic wave device, the metal electrode is manufactured on the piezoelectric film body, and the metal electrode is directly contacted with the second strengthening layer, so that the problem of generating higher harmonic waves caused by direct contact between the piezoelectric film layer and the metal electrode can be avoided; in the process of etching the back substrate, the first enhancement layer can effectively prevent over etching. Because the thickness of the piezoelectric film layer is nanoscale, the strength is lower, the piezoelectric film layer is fragile and easy to crack in the process of preparing a device, the Young modulus of the first strengthening layer and the Young modulus of the second strengthening layer are larger than that of the piezoelectric film layer, the piezoelectric film layer is clamped between the first strengthening layer and the second strengthening layer, the piezoelectric film layer is supported, the strength of the piezoelectric film layer can be enhanced, and the piezoelectric film layer is prevented from being cracked. According to the preparation method of the piezoelectric film body, provided by the application, the piezoelectric film layer and the first reinforcement layer are bonded together by adopting a bonding technology, so that the problems that lattice mismatch, thermal mismatch and interface defects are easy to generate in the conventional piezoelectric film forming method can be solved, and the piezoelectric film layer meeting the high film quality requirement is obtained.
Drawings
In order to more clearly illustrate the technical solution of the present application, the drawings that are needed in the embodiments will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a diagram of a structure of a piezoelectric film bulk layer for fabricating a bulk acoustic wave device according to an embodiment of the present application;
FIG. 2 is a diagram of another structure of a piezoelectric film bulk layer for fabricating a bulk acoustic wave device according to an embodiment of the present application;
FIG. 3 is a process flow diagram of a method for fabricating a piezoelectric thin film device of FIG. 1;
fig. 4 is a process flow diagram of another method for fabricating a piezoelectric thin film body for a bulk acoustic wave device shown in fig. 2.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
With the development of piezoelectric thin film technology, piezoelectric thin films are increasingly applied to the manufacture of bulk acoustic wave devices. At present, the film structure of the piezoelectric film body is usually an oxide-piezoelectric film layer, and the film structure of a bulk acoustic wave device manufactured by adopting the piezoelectric film body is usually a metal-piezoelectric film body-metal.
However, in the fabricated bulk acoustic wave device, the piezoelectric thin film layer is in direct contact with the metal, and higher harmonics are liable to occur, resulting in poor out-of-band suppression effect of the bulk acoustic wave device. When the piezoelectric film body is used for manufacturing the bulk acoustic wave device, the substrate on the back surface needs to be etched, and the etching precision is difficult to control, so that overetching is easy to occur; and because the stress intensity of the piezoelectric film layer is lower, the piezoelectric film layer is easy to crack in the process of manufacturing the device, and the yield of the bulk acoustic wave device is greatly reduced. In addition, the existing film forming method of the piezoelectric film generally adopts pulse laser deposition, magnetron sputtering, atomic layer deposition, thermal evaporation and the like, and the problems of lattice mismatch, thermal mismatch, interface defects and the like are easy to generate.
In view of this, fig. 1 is a diagram of a structure of a piezoelectric thin film layer for fabricating a bulk acoustic wave device according to an embodiment of the present application. As shown in fig. 1, a piezoelectric film body for manufacturing a bulk acoustic wave device includes a film body substrate 1, a first reinforcing layer 2, a piezoelectric film layer 3, and a second reinforcing layer 4, which are sequentially stacked; wherein the Young's moduli of the first reinforcing layer 2 and the second reinforcing layer 4 are larger than the Young's modulus of the piezoelectric thin film layer 3.
The thickness H1 of the first reinforcing layer 2 may be the same as or different from the thickness H3 of the second reinforcing layer, and the thickness H1 of the first reinforcing layer may be in the range of 2nm to 100nm, or may be 10nm. The thickness H2 of the piezoelectric thin film layer 3 is in the range of 100nm to 3000nm, and may be 400nm. The electromechanical coupling coefficient of the film material can be influenced by the excessive thickness of the film layer, so that the electromechanical coupling coefficient of each film material of the piezoelectric film body can be ensured by controlling the thicknesses of the first strengthening layer 2, the piezoelectric film layer 3 and the second strengthening layer 4 at the nanometer level.
The embodiment provides a piezoelectric film body for manufacturing a bulk acoustic wave device, when the piezoelectric film body is used for manufacturing the bulk acoustic wave device, a metal electrode is manufactured on the piezoelectric film body, and the metal electrode is directly contacted with a second strengthening layer 4, so that the problem of generation of higher harmonic waves caused by direct contact between a piezoelectric film layer 3 and the metal electrode can be avoided; the first strengthening layer 2 can effectively prevent over etching during etching of the back substrate. Because the thickness of the piezoelectric film layer 3 is nano-scale, the strength is lower, the piezoelectric film layer 3 is fragile and easy to crack in the process of preparing the device, the Young modulus of the first strengthening layer 2 and the Young modulus of the second strengthening layer 4 are larger than that of the piezoelectric film layer 3, the piezoelectric film layer 3 is clamped between the first strengthening layer 2 and the second strengthening layer 4, the piezoelectric film layer 3 is supported, the strength of the piezoelectric film layer 3 can be enhanced, and the piezoelectric film layer 3 is prevented from being cracked.
The material of the film body substrate 1 can be monocrystalline silicon or lithium niobate, the monocrystalline silicon or lithium niobate can well prevent external impurity ions from entering the piezoelectric film body, and when the piezoelectric film body is used for preparing other devices, the film body substrate 1 needs to be removed, and the monocrystalline silicon or lithium niobate can be removed easily in an etching mode. The material of the first strengthening layer 2 and the second strengthening layer 4 may be aluminum oxide or aluminum nitride; the aluminum oxide film layer or the aluminum nitride film layer prepared by the magnetron sputtering or deposition method has the characteristics of high sound velocity and high Young modulus, and can enhance the supporting effect of the first strengthening layer 2 and the second strengthening layer 4. In addition, when the film body substrate 1 is removed by etching, the aluminum oxide or aluminum nitride will not be etched away, so the first strengthening layer can prevent over etching by using the aluminum oxide or aluminum nitride. Since the properties of lithium tantalate and lithium niobate are similar, the material of the piezoelectric thin film layer 3 may be monocrystalline lithium niobate or monocrystalline lithium tantalate, and the piezoelectric thin film layer 3 is a monocrystalline thin film layer, so that the physical properties of the material, such as electromechanical coupling coefficient and acoustic velocity, can be completely maintained. When the piezoelectric film body is used for preparing the bulk acoustic wave device, the sound velocity of the first strengthening layer 2 and the second strengthening layer 4 is lower than that of the piezoelectric film layer 3 and higher than that of an air medium, so that most of sound waves are reflected when the sound waves propagate to the interface between the piezoelectric film layer 3 and the first strengthening layer 2 or the second strengthening layer 4, and simultaneously, reflection is generated on the interface between the first strengthening layer 2 or the second strengthening layer 4 and air, so that the sound waves can be ensured to be completely reserved in the piezoelectric film body and not leaked to the outside, performance failure of the acoustic wave device can be avoided, generation of higher harmonics can be further restrained, and the out-of-band inhibition effect of the device is improved.
Fig. 2 is a diagram of another structure of a piezoelectric film bulk layer for fabricating a bulk acoustic wave device according to an embodiment of the present application. As shown in fig. 2, the piezoelectric film body further includes an isolation layer 5, and the isolation layer 5 is located between the film body substrate 1 and the first strengthening layer 2. The material of the isolation layer 5 may be silicon dioxide or silicon nitride. Since the thin film body substrate 1 needs to be removed when the piezoelectric thin film body is used for manufacturing a bulk acoustic wave device, silicon dioxide or silicon nitride as the isolation layer 5 may function as a protection first strengthening layer for isolating foreign ions from the outside after the thin film body substrate 1 is removed.
In another aspect, fig. 3 is a process flow diagram of a method for fabricating a piezoelectric film for fabricating a bulk acoustic wave device as shown in fig. 1. As shown in fig. 3, a method for manufacturing a piezoelectric thin film body for a bulk acoustic wave device includes:
s1: a first strengthening layer 2 is fabricated on a film bulk substrate 1.
S1, manufacturing a first strengthening layer 2 on a film body substrate 1 can comprise:
s11: the first strengthening layer 2 is fabricated on the thin film body substrate 1 by means of magnetron sputtering or atomic deposition.
S12: the first strengthening layer 2 is subjected to polishing treatment so that the thickness of the first strengthening layer 2 is in the range of 2nm to 100nm.
The film body substrate 1 can be a monocrystalline silicon wafer or a monocrystalline lithium niobate wafer with a diameter of 3 inches and a thickness of 0.4mm, and the roughness of the wafer surface can be less than 0.5nm; the first strengthening layer 2 may be formed on the smoother side of the film body substrate 1. The first strengthening layer 2 can be aluminum oxide or aluminum nitride, and the film quality is uniform, wherein the aluminum oxide or aluminum nitride is formed by magnetron sputtering or atomic deposition. The polishing process can enable the surface of the first strengthening layer 2 to be smoother and the film thickness to be more uniform, and further, other film layers are facilitated to be adhered to the first strengthening layer 2.
S2: and manufacturing a piezoelectric film layer on the first reinforced layer by an ion implantation bonding method.
S2, manufacturing a piezoelectric film layer on the first reinforced layer by an ion implantation bonding method, wherein the method comprises the following specific steps:
s21: helium ions are implanted into the surface of the piezoelectric thin film body material, and the piezoelectric thin film layer 3, the separation layer, and the remainder layer are formed in this order on the ion implantation side of the piezoelectric thin film body material.
The piezoelectric film body material can be layered by helium ion implantation, the piezoelectric film layer 3 is positioned on the surface of the piezoelectric film body material, the separation layer is positioned between the piezoelectric film layer 3 and the remainder layer, the implanted helium ions are distributed in the separation layer, and the piezoelectric film body material can be a lithium niobate wafer or a lithium tantalate wafer with the diameter of 3 inches and the thickness of 0.4 mm. Helium ion implantation energy is 50-1000KeV, which can be 200KeV, and dosage is 1E16-1E17ions/cm 2 May be 4E16ions/cm 2 The present application is not particularly limited.
S22: the piezoelectric film layer 3 is bonded to the first reinforcing layer 2.
In step S22, a bonding technique, which may be any one of direct bonding, anodic bonding, low-temperature bonding, vacuum bonding, plasma enhanced bonding, and adhesive bonding, is used to bond the piezoelectric thin film layer 3 and the first enhanced layer 2 together, so as to obtain a bonded body. The problem that lattice mismatch, thermal mismatch and interface defects are easy to generate in the existing piezoelectric film forming method can be solved, and the piezoelectric film layer 3 meeting the high film quality requirement can be obtained.
S23: the residual material layer is separated from the piezoelectric film layer 3 by a thermal peeling process.
After the piezoelectric film layer 3 and the first reinforcing layer 2 are bonded together, the bonded body is placed in a heating device, heat is preserved at a temperature ranging from 100 ℃ to 600 ℃, the heat preservation environment can be one of a vacuum environment, a nitrogen environment or an inert gas environment, the heat preservation time ranges from 1 minute to 48 hours, and can be 3 hours or 4 hours, until the piezoelectric film layer 3 is separated from the residual material layer at the separation layer, and the piezoelectric film layer 3 is kept on the bonded body.
S3: a second strengthening layer is formed on the piezoelectric thin film layer 3 to obtain a piezoelectric thin film body for manufacturing a bulk acoustic wave device.
S3, manufacturing a second strengthening layer on the piezoelectric film layer 3 to obtain a piezoelectric film body for manufacturing the bulk acoustic wave device, wherein the method can comprise the following steps of:
s31: the second strengthening layer 4 is fabricated on the piezoelectric thin film layer 3 by means of magnetron sputtering or atomic deposition.
S32: and polishing the second strengthening layer 4 to ensure that the thickness of the second strengthening layer 4 ranges from 2nm to 100nm, thereby obtaining the piezoelectric film body for manufacturing the bulk acoustic wave device.
The second strengthening layer 4 and the first strengthening layer 2 may be formed in the same manner or in different manners, and the present application is not particularly limited. The thickness of the second reinforcing layer 4 may be the same as or different from the thickness of the first reinforcing layer 2, and the present application is not particularly limited.
Fig. 4 is a process flow diagram of another method for fabricating a piezoelectric thin film body for a bulk acoustic wave device shown in fig. 2. As shown in fig. 4, another method for manufacturing a piezoelectric film body for a bulk acoustic wave device according to this embodiment includes the following steps:
s0: an isolation layer 5 is formed on the film body substrate 1.
The isolation layer 5 may be silicon dioxide or silicon nitride, and may be formed by plasma chemical vapor deposition, and the present application is not particularly limited. The film body substrate 1 can be a monocrystalline silicon wafer or a monocrystalline lithium niobate wafer with a diameter of 3 inches and a thickness of 0.4mm, and the roughness of the wafer surface can be less than 0.5nm; the spacer layer 5 may be formed on the smoother side surface of the film body substrate 1. The isolation layer 5 can be polished after film formation, and the isolation layer 5 can be better adhered with other film layers after the polishing treatment.
S1: a first strengthening layer 2 is made on the isolating layer 5.
The first strengthening layer 2 can be aluminum oxide or aluminum nitride, and the film quality is uniform, wherein the aluminum oxide or aluminum nitride is formed by magnetron sputtering or atomic deposition. The first strengthening layer 2 can be polished after being formed into a film, so that the surface of the first strengthening layer 2 is smoother and the film thickness is more uniform, and further, other film layers are favorably adhered to the first strengthening layer 2.
S2: a piezoelectric thin film layer 3 is formed on the first reinforcing layer 2 by an ion implantation bonding method.
Ion implantation is performed on the piezoelectric film body material, so that the piezoelectric film body material can be layered and divided into a residual material layer, a separation layer and a piezoelectric film layer 3, wherein the piezoelectric film layer 3 is positioned on the surface of the piezoelectric film body material, and the separation layer is positioned between the residual material layer and the piezoelectric film layer 3. The bonding method can be any one of a direct bonding method, an anode bonding method, a low-temperature bonding method, a vacuum bonding method, a plasma strengthening bonding method and a bonding method, and the first strengthening layer and the piezoelectric film layer 3 can be bonded together through the bonding method, so that the problems that lattice mismatch, thermal mismatch and interface defects are easy to generate in the conventional film forming method of the piezoelectric film layer can be avoided, and the piezoelectric film layer 3 meeting the high film quality requirement is further obtained.
S3: a second strengthening layer 4 is formed on the piezoelectric thin film layer 3 to obtain a piezoelectric thin film body for manufacturing a bulk acoustic wave device.
When the piezoelectric film body for manufacturing the bulk acoustic wave device is used for manufacturing the bulk acoustic wave device, the metal electrode is manufactured on the piezoelectric film body, and the metal electrode is directly contacted with the second strengthening layer, so that the problem of generation of higher harmonic waves caused by direct contact between the piezoelectric film layer and the metal electrode can be avoided; in the process of etching the back substrate, the first enhancement layer can effectively prevent over etching. Because the thickness of the piezoelectric film layer is nanoscale, the strength is lower, the piezoelectric film layer is fragile and easy to crack in the process of preparing the device, the Young modulus of the first strengthening layer and the Young modulus of the second strengthening layer are larger than that of the piezoelectric film layer, the piezoelectric film layer is clamped between the first strengthening layer and the second strengthening layer, the piezoelectric film layer is supported, the strength of the piezoelectric film layer can be enhanced, and the piezoelectric film layer is protected from being cracked. According to the preparation method of the piezoelectric film body, provided by the application, the piezoelectric film layer and the first reinforcement layer are bonded together by adopting a bonding technology, so that the problems that lattice mismatch, thermal mismatch and interface defects are easy to generate in the conventional piezoelectric film forming method can be solved, and the piezoelectric film layer meeting the high film quality requirement is obtained. The first strengthening layer and the second strengthening layer are prepared on two sides of the piezoelectric film layer, the piezoelectric film layer is clamped between the first strengthening layer and the second strengthening layer, the piezoelectric film layer is supported, the strength of the piezoelectric film layer can be enhanced, and the piezoelectric film layer is prevented from being broken.
The same or similar parts between the various embodiments in this specification are referred to each other. In particular, for the embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference should be made to the description of the method embodiments for the matters.
Claims (10)
1. A piezoelectric film body for manufacturing a bulk acoustic wave device is characterized by comprising a film body substrate, a first strengthening layer, a piezoelectric film layer and a second strengthening layer which are sequentially overlapped;
the Young modulus of the first strengthening layer and the Young modulus of the second strengthening layer are larger than that of the piezoelectric film layer, and the sound velocity of the first strengthening layer and the second strengthening layer is lower than that of the piezoelectric film layer and higher than that of an air medium.
2. The piezoelectric film body of claim 1, further comprising an isolation layer between the film body substrate and the first stiffening layer.
3. The piezoelectric thin film body according to claim 2, wherein the thickness of the first strengthening layer ranges from 2nm to 100nm, and the thickness of the second strengthening layer ranges from 2nm to 100nm;
the thickness of the piezoelectric film layer ranges from 100nm to 3000nm.
4. The piezoelectric thin film body according to claim 2, wherein the material of the thin film body substrate is monocrystalline silicon or lithium niobate.
5. The piezoelectric thin film body according to claim 2, wherein the material of the first reinforcing layer and the second reinforcing layer is aluminum oxide or aluminum nitride;
the piezoelectric film layer is made of lithium niobate or lithium tantalate.
6. The piezoelectric thin film body according to claim 2, wherein the material of the isolation layer is silicon dioxide or silicon nitride.
7. A method of fabricating a piezoelectric thin film body for a bulk acoustic wave device, comprising:
manufacturing a first strengthening layer on a film body substrate;
manufacturing a piezoelectric film layer on the first reinforced layer by an ion implantation bonding method;
manufacturing a second strengthening layer on the piezoelectric film layer to obtain a piezoelectric film body for manufacturing a bulk acoustic wave device, wherein Young modulus of the first strengthening layer and Young modulus of the second strengthening layer are larger than Young modulus of the piezoelectric film layer; the sound velocity of the first strengthening layer and the second strengthening layer is lower than that of the piezoelectric film layer and higher than that of an air medium.
8. The method as recited in claim 7, further comprising:
an isolation layer is fabricated on the film body substrate prior to fabricating the first stiffening layer.
9. The method of claim 7, wherein fabricating the first strengthening layer on the thin film bulk substrate comprises:
manufacturing a first strengthening layer on the film body substrate by means of magnetron sputtering or atomic deposition;
and polishing the first strengthening layer to ensure that the thickness of the first strengthening layer ranges from 2nm to 100nm.
10. The method of claim 7, wherein fabricating a second stiffening layer on the piezoelectric film layer results in a piezoelectric film body for fabricating a bulk acoustic wave device, comprising:
manufacturing a second strengthening layer on the piezoelectric film layer by means of magnetron sputtering or atomic deposition;
and polishing the second strengthening layer to ensure that the thickness of the second strengthening layer ranges from 2nm to 100nm, thereby obtaining the piezoelectric film body for manufacturing the bulk acoustic wave device.
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| CN1256663A (en) * | 1998-02-18 | 2000-06-14 | 索尼株式会社 | Piezoelectric actuator, method of manufacture, and ink-jet print head |
| JP2011166365A (en) * | 2010-02-08 | 2011-08-25 | Yamaha Corp | Piezoelectric sounding device and method of manufacturing the same |
| CN104078560A (en) * | 2013-03-25 | 2014-10-01 | 日立金属株式会社 | Piezoelectric thin-film multilayer body |
| CN107742607A (en) * | 2017-08-31 | 2018-02-27 | 重庆中科渝芯电子有限公司 | A kind of method that film resistor is made of ICP dry etchings |
| CN110113022A (en) * | 2019-05-13 | 2019-08-09 | 南方科技大学 | A kind of thin film bulk acoustic wave resonator and preparation method thereof |
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| WO2014087799A1 (en) * | 2012-12-05 | 2014-06-12 | 株式会社村田製作所 | Piezoelectric member, elastic wave apparatus, and piezoelectric member manufacturing method |
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| CN1256663A (en) * | 1998-02-18 | 2000-06-14 | 索尼株式会社 | Piezoelectric actuator, method of manufacture, and ink-jet print head |
| JP2011166365A (en) * | 2010-02-08 | 2011-08-25 | Yamaha Corp | Piezoelectric sounding device and method of manufacturing the same |
| CN104078560A (en) * | 2013-03-25 | 2014-10-01 | 日立金属株式会社 | Piezoelectric thin-film multilayer body |
| CN107742607A (en) * | 2017-08-31 | 2018-02-27 | 重庆中科渝芯电子有限公司 | A kind of method that film resistor is made of ICP dry etchings |
| CN110113022A (en) * | 2019-05-13 | 2019-08-09 | 南方科技大学 | A kind of thin film bulk acoustic wave resonator and preparation method thereof |
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