US20150022274A1 - Piezoelectric film producing process, vibrator element, vibrator, oscillator, electronic device, and moving object - Google Patents
Piezoelectric film producing process, vibrator element, vibrator, oscillator, electronic device, and moving object Download PDFInfo
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- US20150022274A1 US20150022274A1 US14/330,626 US201414330626A US2015022274A1 US 20150022274 A1 US20150022274 A1 US 20150022274A1 US 201414330626 A US201414330626 A US 201414330626A US 2015022274 A1 US2015022274 A1 US 2015022274A1
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Images
Classifications
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- H01L41/09—
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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
- H03H9/15—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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/12—Alloys based on aluminium with copper as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/0688—Cermets, e.g. mixtures of metal and one or more of carbides, nitrides, oxides or borides
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/14—Metallic material, boron or silicon
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/34—Sputtering
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/34—Sputtering
- C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
- C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
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- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
- H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/09—Forming piezoelectric or electrostrictive materials
- H10N30/092—Forming composite materials
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
- H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
- H10N30/2041—Beam type
- H10N30/2042—Cantilevers, i.e. having one fixed end
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/853—Ceramic compositions
Definitions
- the present invention relates to a piezoelectric film producing process, a vibrator element that includes a piezoelectric film produced by the process, and vibrators, oscillators, electronic devices, and moving objects that include the vibrator element.
- a piezoelectric thin film resonator (hereinafter, referred to as “vibrator element”) is known that is configured to include a lower electrode provided on a substrate, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film, and having a region opposite the lower electrode with the piezoelectric film in between (see, for example, JP-A-2013-34130).
- the vibrator element uses aluminum nitride (hereinafter, “AlN”) for the piezoelectric film.
- AlN aluminum nitride
- the piezoelectric film is deposited (formed) by spattering, using Al (aluminum) as the target material (deposition material) in a mixed atmosphere of N 2 (nitrogen) gas and Ar (argon) gas,
- the piezoelectric film uses pure aluminum as deposition material
- processes such as the deposition of the upper electrode after the AlN deposition may produce internal stress in the aluminum present at the crystal grain boundaries of the deposited AlN.
- the piezoelectric film thus involves the risk of generating stress migration, forming voids in the aluminum.
- the resulting degradation of electromechanical coupling coefficient increases the impedance of the piezoelectric film. This may cause deterioration in the function of the piezoelectric film, and the reliability (long-term reliability in particular) may suffer as a result of the progression of stress migration (e.g., void diffusion).
- An advantage of some aspects of tine invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
- a piezoelectric film producing process includes depositing a piezoelectric film in a mixed atmosphere of N 2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material.
- the piezoelectric film producing process includes depositing a piezoelectric film in a mixed atmosphere of N 2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material (target material).
- the piezoelectric film producing process uses an Al—Cu alloy as the deposition material of the piezoelectric film, the copper exists by being dispersed in aluminum, at the crystal grain boundaries of the piezoelectric film (specifically, AlN film) deposited by sputtering (in other words, intermetallic compound (Al 3 Cu) is produced).
- the piezoelectric film producing process can thus improve the function of the piezoelectric film, as compared to the producing process of related art (for example, JF-A-2013-34130), and can suppress stress migration to improve the reliability of the piezoelectric film.
- the Cu content in the Al—Cu alloy ranges from 0.25 mass % to 1.0 mass %.
- the piezoelectric film producing process can suppress Al diffusion at the crystal grain boundaries, and generation of stress migration.
- the Cu content in the Al—Cu alloy ranges from 0.4 mass % to 0.6 mass %.
- the piezoelectric film producing process can further suppress Al diffusion at the crystal grain boundaries, and generation of stress migration.
- the mixture ratio of the N 2 gas and the Ar gas ranges from N 2 gas 50 volume %:Ar gas 50 volume % to N 2 gas 99 volume %:Ar gas 1 volume %.
- the piezoelectric film producing process can produce a desirably functioning piezoelectric film (specifically, AlN film) by using a sputtering method.
- a vibrator element includes a base portion, and a vibrating arm extending from the base portion, wherein the vibrating arm includes a piezoelectric film that contains Cu at a crystal grain boundary.
- the vibrator element includes a base portion, and a vibrating arm extending from the base portion, and the vibrating arm includes a piezoelectric film (specifically, AIM film) that contains Cu at the crystal grain boundary. This makes it possible to suppress generation of stress migration in the piezoelectric film.
- AIM film specifically, AIM film
- the vibrator element can thus improve the function of the piezoelectric film as compared to related art (for example, JP-A-2013-34130), and the reliability of the piezoelectric film.
- the vibrator element By thus lowering the CI value, the vibrator element can improve its vibration characteristics and reliability.
- a vibrator according to this application Example includes the vibrator element according to the application example described above, and a package housing the vibrator element.
- the vibrator of this configuration includes the vibrator element according to the application example described above, and a package housing the vibrator element. This makes it possible to provide a highly reliable vibrator having the effects described in the application example described above.
- An oscillator according to this application example includes the vibrator element according to the application example described above, and an oscillation circuit that oscillates the vibrator element.
- the oscillator of this configuration includes the vibrator element according to the application example described above, and an oscillation circuit that oscillates the vibrator element. This makes it possible to provide a highly reliable oscillator having the effects described in the application example described above.
- An electronic device includes the vibrator element according to the application example described above.
- the electronic device of this configuration includes the vibrator element according to the application example described above. This makes it possible to provide a highly reliable electronic device having the effects described in the application example described above.
- a moving object according to this application example includes the vibrator element according to the application example described above.
- the moving object of this configuration includes the vibrator element according to the application example described above. This makes it possible to provide a highly reliable moving object having the effects described in the application example described above.
- FIGS. 1A and 1B are schematic diagrams illustrating a schematic structure of a vibrator element of First Embodiment, in which FIG. 1A is a plan view, and FIG. 1B is a cross sectional view taken at line A-A of FIG. 1A .
- FIG. 2 is a cross sectional view taken at line B-B of FIG. 1A , shown alongside with a wiring diagram of each excitation electrode.
- FIG. 3 is a schematic diagram explaining a piezoelectric body producing process.
- FIG. 4 is a diagram representing piezoelectric body deposition conditions, and corresponding evaluation results.
- FIGS. 5A and 5B are schematic diagrams illustrating a schematic structure of a vibrator of Second Embodiment, in which FIG. 5A is a plan view as viewed from the lid (cap) side, and FIG. 5B is a cross sectional view taken at line C-C of FIG. 5A .
- FIGS. 6A and 6B are schematic diagrams illustrating a schematic structure of an oscillator of Third Embodiment, in which FIG. 6A is a plan view as viewed from the lid side, and FIG. 6B is a cross sectional, view taken at line C-C of FIG. 6A .
- FIG. 7 is a schematic perspective view of a cell phone of Fourth Embodiment.
- FIG. 8 is a schematic perspective view of an automobile of Fifth Embodiment.
- a vibrator element that uses a Si (silicon) base material is described as an example of the vibrator element.
- FIGS. 1A and 1B are schematic diagrams illustrating a schematic structure of the vibrator element of First Embodiment.
- FIG. 1A is a plan view
- FIG. 1B is a cross sectional view taken at line A-A of FIG. 1A . Wires are omitted, and the dimensional ratio of each constituting element differs from the actual dimension ratios.
- FIG. 2 is a cross sectional view taken at line B-B of FIG. 1A , shown alongside with a wiring diagram of each excitation electrode.
- the X, Y, and Z axes are coordinate axes that are orthogonal to each other.
- the base material of a vibrator element 1 includes a base portion 10 , and three vibrating arms 11 a, 11 b , and 11 c extending from the base portion 10 in Y-axis direction.
- a Si substrate for example, a SOI-, or Poly-Si-deposited substrate
- the base portion 10 is used for the three vibrating arms 11 a , 11 b , and 11 c , and the base portion 10 .
- the vibrating arms 11 a, 11 b , and 11 c have a form of substantially a rectangular column.
- the vibrating arms 11 a , 11 b , and 11 c include excitation electrodes 12 a, 12 b, and 12 c .
- the excitation electrodes 12 a, 12 b, and 12 c are aligned in X-axis direction orthogonal to Y-axis direction in planar view, and are provided on at least one of major surfaces 10 a and 10 b (here, on the major surface 10 a ) that lie on the plane (XY plane) specified by X axis and Y axis,
- the excitation electrodes 12 a, 12 b, and 12 c cause flexural vibration (antiplane vibration: occurring in directions that are not along the major surface 10 a ) in the vibrating arras 11 a, 11 b , and 11 c along Z-axis direction orthogonal to the major surface 10 a (the direction of arrow in FIG. 1B ).
- the base portion 10 , the vibrating arms 11 a, 11 b , and 11 c , and the excitation electrodes 12 a, 12 b, and 12 c are formed with high accuracy by using methods, for example, such as sputtering, photolithography, and etching.
- the excitation electrodes 12 a, 12 b, and 12 c have a laminate structure including first electrodes 12 a 1 , 12 b 1 , and 12 c 1 provided on the major surface 10 a side, second electrodes 12 a 2 , 12 b 2 , and 12 c 2 provided above the first electrodes 12 a 1 , 12 b 1 , and 12 c , a piezoelectric body 13 disposed as a piezoelectric film between the first electrodes 12 a , 12 b 1 , and 12 c 1 and the second electrodes 12 a 2 , 12 b 2 , and 12 c 2 , and an insulating film 14 provided between the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 and the piezoelectric body 13 .
- the insulating film 14 may be omitted.
- the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 , and the second electrodes 12 a 2 , 12 b 2 , and 12 c 2 of the excitation electrodes 12 a, 12 b, and 12 c use a film that contains TIN (titanium nitride).
- the piezoelectric body 13 uses a film that contains AlN (aluminum nitride).
- the insulating film 14 uses a film that contains amorphous SiO 2 (silicon dioxide).
- the piezoelectric body 13 is formed (deposited) by sputtering, using an Al—Cu alloy as deposition material (target material), as will be described later in detail.
- the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 , and the second electrodes 12 a 2 , 12 b 2 , and 12 c 2 of the excitation electrodes 12 a , 12 b, and 12 c nave a thickness of preferably about 15 nm.
- the piezoelectric body 13 has a thickness of preferably about 200 nm to 400 nm
- the insulating film 14 has a thickness of preferably about 10 nm.
- the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 , and the second electrodes 12 a 2 , 12 b 2 , and 12 c 2 may use a film containing materials (for example, such as Mo, Ti, Ni, Pt, Au, W, WSi, Ta, and ITO) different from TiN.
- a film containing materials for example, such as Mo, Ti, Ni, Pt, Au, W, WSi, Ta, and ITO
- the excitation electrodes 12 a, 12 b, and 12 c extend towards the tip portion from the root portion of the vibrating arms 11 a , 11 b , and 11 c (the boundary portion from the base portion 10 ) in about a half length of the full length (from the root to the tip along Y-axis direction) of the vibrating arms 11 a, 11 b , and 11 c.
- the base portion 10 is thicker than the vibrating arms 11 a , 11 b , and 11 c in Z-axis direction.
- the base portion 10 has fixing portions 10 c and 10 d providing regions for fixing external members such as a package.
- the fixing portions 10 c and 10 d are provided on the major surface 10 b side of the base portion 10 at the both ends relative to X-axis direction, as indicated by long dashed double-short dashed line in FIG. 1A , Preferably, the fixing portions 10 c and 10 d are provided at the end of the base portion 10 opposite the vibrating arms 11 a , 11 b , and 11 c in Y-axis direction.
- the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 , and the second electrodes 12 a 2 , 12 b 2 , and 12 c 2 of the excitation electrodes 12 a, 12 b, and 12 c in the vibrator element 1 are connected to an alternate current power supply by crossed wires, and a driving alternating voltage is applied to these electrodes.
- the first electrode 12 a 1 of the vibrating arm 11 a , the second electrode 12 b 2 of the vibrating arm 11 b , and the first electrode 12 c l of the vibrating arm 11 c are connected to bring these electrodes at the same potential.
- the second electrode 12 a 2 of the vibrating arm 11 a, the first electrode 12 b 1 of the vibrating arm 11 b , and the second electrode 12 c 2 of the vibrating arm 11 c are connected to bring these electrodes at the same potential.
- the vibrator element 1 is configured so that the direction of the electric field generated by the crossed wires in the excitation electrodes 12 a and 12 c becomes opposite of that generated in the excitation electrode 12 b, and the piezoelectric body 13 expands and contracts in opposite ways between the vibrating arms 11 a and 11 c and the vibrating arm 11 b.
- the piezoelectric body 13 of the vibrating arm 11 b contracts when the piezoelectric bodies 13 of the vibrating arms 11 a and lie expand
- the piezoelectric body 13 of the vibrating arm lib expands when the piezoelectric bodies 13 of the vibrating arms 11 a and lie contract.
- the vibrating arms 11 a, 11 b , and 11 c bend in the direction of black arrow when the alternating voltage is at one potential, and in the direction of blank arrow when the alternating voltage is at the other potential.
- the vibrating arms 11 a , 11 b , and 11 c in the vibrator element 1 undergo flexural vibration (antiplane vibration) in Z-axis direction.
- flexural vibration occurs in reverse direction (reverse phase) between the adjacent vibrating arms (between 11 a and 11 b , and between 11 b and 11 c in this embodiment).
- a process for producing the piezoelectric body 13 as a constituting element of the excitation electrodes 12 a , 12 b, and 12 c of the vibrator element 1 is described below (piezoelectric film producing process).
- FIG. 3 is a schematic diagram explaining the piezoelectric body producing process.
- the vibrator element 1 with the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 (not illustrated in the figure) and the insulating film 14 is set on a base mount 51 in a vacuum chamber 50 .
- N 2 (nitrogen) gas and Ar (argon) gas are introduced into the vacuum chamber 50 with a vacuum pump or the like (not illustrated) to produce a mixed atmosphere of N 2 gas and Ar gas.
- the pressure inside the vacuum chamber 50 is preferably about 0.53 Pa (4 mTorr).
- the N 2 gas and Ar gas mixture ratio preferably ranges from N 2 gas 50 volume %: Ar gas 50 volume % to N 2 gas 99 volume %:Ar gas 1 volume %.
- the vibrator element 1 is preferably kept at ordinary temperature.
- An Al—Cu alloy 52 as deposition material (target material) is then set on a target mount 53 .
- the Cu content in the Al—Cu alloy is preferably 0.25 mass % to 1.0 mass %, more preferably 0.4 mass % to 0.6 mass %.
- a power supply 54 applies voltage (for example, about 100 V to 1,000 V) by using a sputtering method (reactive sputtering), using the Al—Cu. alloy 52 as cathode, and the vibrator element 1 as anode.
- voltage for example, about 100 V to 1,000 V
- sputtering method reactive sputtering
- the ion atoms in the mixed gas of it gas and Ar gas sputter the surface of the Al—Cu alloy 52 , and the particles (atoms and molecules) jumped out of the Al—Cu alloy 52 deposit and fix to the vibrator element 1 , covering the insulating film 14 . This deposits (forms) the piezoelectric body 13 (AlN film).
- the piezoelectric body 13 is then patterned into a desired shape by using methods such as photolithography, and etching.
- the piezoelectric body 13 can be obtained in this manner after these steps.
- the process for producing the piezoelectric body 13 of the present embodiment includes depositing the piezoelectric body 13 (piezoelectric film) in a mixed atmosphere of N 2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material (target material).
- the piezoelectric film producing process uses the Al—Cu alloy as deposition material for the deposition of the piezoelectric body 13 , the copper exists by being dispersed in aluminum at the crystal grain boundaries of the piezoelectric body 13 (specifically, AlN film) deposited as the piezoelectric film by sputtering (in other words, intermetallic compound (Al 3 Cu) is produced).
- the piezoelectric film producing process can thus improve the function of the piezoelectric body 13 as compared to the producing process of related art (for example, JP-A-2013-34130), and can suppress stress migration to improve the reliability of the piezoelectric body 13 .
- the piezoelectric film producing process can suppress Al diffusion at the crystal grain boundaries of the piezoelectric body 13 , and thus generation of stress migration.
- the piezoelectric film producing process can further suppress Al diffusion at the crystal grain boundaries of the piezoelectric body 13 , and thus generation of stress migration.
- the piezoelectric body 13 (specifically, AlN film) produced by the piezoelectric film producing process by sputtering can be desirably functional.
- FIG. 4 is a diagram representing piezoelectric body deposition conditions (N 2 gas and Ar gas mixture ratios), and corresponding evaluation results for each sample.
- the sheet resistance of the piezoelectric body 13 should, be about at least 30,000 ⁇ (ohm square), and a 3- to 4-degree angle is considered sufficient for FWHM (half width of the peak in the X-ray diffraction orientation evaluation of the piezoelectric body 13 ).
- the Cu content in the deposition material Al—Cu alloy of the piezoelectric body 13 is 0.5 mass %.
- sample No. 1 N 2 gas 99 volume %:Ar gas 1 volume %; in the following, the unit “volume %” will be omitted) has a sheet resistance of infinity ⁇ , and an FWHM of 3.18 degrees, and the evaluation result is “Good”.
- Sample No. 2 (N 2 gas 80:Ar gas 20) has a sheet resistance of infinity ⁇ , and an FWHM of 3.42 degrees, and the evaluation result is “Good”.
- Sample No. 3 (N 2 gas 70:Ar gas 30) has a sheet resistance of infinity ⁇ and an FWHM of 3.43 degrees, and the evaluation result is “Good”.
- Sample No. 4 (N 2 gas 60:Ar gas 40) has a sheet resistance of infinity ⁇ , and an FWHM of 3.69 degrees, and the evaluation result is “Good”.
- Sample No. 5 gas 50 Ar gas 50
- sample ho. 6 (N 2 gas 40 :Ar gas 60) has a sheet resistance of 0.3100 ⁇ , and the FWHM is incalculable (the peak is unclear, and the half width cannot be calculated), and the evaluation result is “Poor”.
- Sample No. 7 (N 2 gas 10:Ar gas 90) has a sheet resistance of 0.0621 ⁇ , and the FWHM is incalculable (the peak is unclear, and the half width cannot be calculated), and the evaluation result is “Poor”.
- the vibrator element 1 of the present embodiment includes the base portion 10 , and the vibrating arms 11 a , 11 b , and 11 c extending from the base portion 10 , and the piezoelectric body 13 provided for the vibrating arms 11 a , 11 b , and 11 c is a piezoelectric film formed by using the Al—Cu alloy as deposition material. This makes it possible to suppress stress migration generation in the piezoelectric body 13 .
- the vibrator element 1 can thus improve the function of the piezoelectric body 13 (specifically, for example, expansion and contraction capability under applied electric field) as compared to related art (for example, JP-A-2013-34130), and the reliability of the piezoelectric body 13 .
- the vibrator element 1 By thus lowering the CI value, the vibrator element 1 can improve its vibration characteristics and reliability.
- the vibrator element 1 may include a SiO 2 -containing film between the major surface 10 a and the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 of the vibrating arms 11 a, 11 b , and 11 c.
- the SiO 2 -containing film in the vibrator element 1 functions as a temperature characteristics correction film for the vibrating arms 11 a, 11 b , and 11 c.
- the slope of the frequency-temperature characteristics of one SiO 2 -containing film in the vibrator element 1 corrects (cancels) the slope of the frequency-temperature characteristics of the vibrating arms 11 a, 11 b , and 11 c that use Si as base material, and produces flat frequency-temperature characteristics.
- the vibrator element 1 can suppress frequency fluctuations due to temperature changes, and can improve the frequency-temperature characteristics.
- the SiO 2 -containing film may be provided on the opposite side (the major surface 10 b side) of the first electrodes 12 a 1 , 12 b 1 , and 12 c 1 (the major surface 10 a side) of the vibrating arms 11 a, 11 b , and 11 c .
- FIGS. 5A and 5B are schematic diagrams illustrating a schematic structure of the vibrator of Second Embodiment.
- FIG. 5A is a plan view as viewed from the lid (cap) side
- FIG. 5B is a cross sectional view taken at line C-C of FIG. 5A .
- the lid is emitted, in the plan view. Wires are also omitted.
- a vibrator 5 includes the vibrator element 1 described in First Embodiment, and a package 20 housing the vibrator element 1 .
- the package 20 is substantially cuboid in shape, and includes a package base 21 having a substantially rectangular planar shape with a depression, and a plate-shaped lid 22 having a substantially rectangular planar shape covering the depression of she package base 21 .
- the package base 21 uses, for example, materials such as an aluminum, oxide sintered body obtained by laminating and sintering a molded ceramic green sheet. Other examples include crystals, glass, and Si.
- the lid 22 uses the same material used for the package base 21 , or metals such as kovar, and 42 alloy.
- the package base 21 includes inner terminals 24 and 25 on an inner bottom surface (the bottom surface inside the depression) 23 .
- the inner terminals 24 and 25 are substantially rectangular in shape, and are formed in the vicinity of interconnection electrodes 18 a and 18 b provided on the base portion 10 of the vibrator element 1 .
- the interconnection electrodes 18 a and 18 b are connected to the first electrode (e.g., 12 b 1 ) and the second electrode (e.g., 12 b 2 ) of each excitation electrode (e.g., 12 b ) of the vibrator element 1 via wires (not illustrated).
- the wire on one side of the alternate current power supply is connected to the interconnection electrode 18 a, and the wire on the other side of the alternate current power supply is connected to the interconnection electrode 18 b.
- a pair of external terminals 27 and 28 for mounting external members such as an electronic device is formed on an outer bottom surface (the surface opposite the inner bottom surface 23 ; the bottom surface on the outer side) 26 of the package base 21 .
- the external terminals 27 and 28 are connected to the inner terminals 24 and 25 via inner wires (not illustrated).
- the external terminal 27 is connected to the inner terminal 24
- the external terminal 28 is connected to the inner terminal 25 .
- the inner terminals 24 and 25 , and the external terminals 27 and 28 use laminated metal films obtained by laminating coating materials such as Ni and Au on a metallization layer such as W and Mo, using a method such as plating.
- the filing portions 10 c and 10 d of the base portion 10 of the vibrator element 1 are fixed to the inner bottom surface 23 of the package base 21 via an adhesive 30 of materials such as epoxy, silicone, and polyimide.
- the interconnection electrodes 18 a and 18 b of the vibrator element 1 are connected to the inner terminals 24 and 25 via metal wires 31 of materials such as Au and Al.
- inside of the package 20 is sealed air-tightly by bonding the package base 21 and the lid 22 to each other with a bonding member 29 such as a seam ring, low-melting-point glass, and an adhesive after covering the depression of the package base 21 with the lid 22 with the vibrator element 1 being connected to the inner terminals 24 and 25 of the package base 21 .
- a bonding member 29 such as a seam ring, low-melting-point glass
- the package may be configured from, for example, a plate-shaped package base, and a depressed lid.
- the package may have a depression in both the package base and the lid,
- the base portion 10 of the vibrator element 1 may be fixed at portions other than the fixing portions 10 c and 10 d , for example, at a point that includes the center of a straight line connecting the fixing portion 10 c and the fixing portion 10 d to each other, instead of using the fixing portions 10 c and 10 d.
- the vibrating arms (e.g., 11 b ) of the vibrator element 1 in the vibrator 5 oscillate (resonate) in thickness direction (direction of arrow in FIG. 5B ) at a predetermined frequency (for example, about 32.768 kHz).
- the vibrator 5 of Second Embodiment can have high reliability, and can exhibit the effects described in First Embodiment.
- FIGS. 6A and 6B are schematic diagrams illustrating a schematic structure of the oscillator of Third Embodiment.
- FIG. 6A is a plan view as viewed from the lid side
- FIG. 6B is a cross sectional view taken at line C-C of FIG. 6A .
- the lid, and some of other constituting elements are omitted in the plan view. Wires are also omitted.
- an oscillator 6 includes the vibrator element 1 described in Burst Embodiment, an IC chip 40 provided as an oscillation circuit for oscillating the vibrator element 1 , and a package 20 housing the vibrator element 1 and she IC chip 40 .
- Inner connection terminals 23 a are provided on an inner bottom surface 23 of a package base 21 .
- the IC chip 40 installing the oscillation circuit is fixed to the inner bottom surface 23 of the package base 21 with an adhesive or the like (not illustrated).
- the IC chip 40 is connected to the inner connection terminals 23 a as interconnection pads (not illustrated), using metal wires 41 of materials such as Au and Al.
- the inner connection terminals 23 a are formed of a laminated metal film obtained by laminating coating materials such as Ni and Au on a metallization layer such as W and Mo, using a method such as plating, and are connected to, for example, the external terminals 27 and 28 , and the inner terminals 24 and 25 of the package 20 via inner wires (not illustrated).
- the interconnection pads of the IC chip 40 and the inner connection terminals 23 a may be connected to each other by using, for example, an interconnection method based on flip-chip mounting, by flipping the IC chip 40 .
- the vibrating arms (e.g., 11 b ) of the vibrator element 1 in the oscillator 6 oscillate (resonate) at a predetermined frequency (for example, about 32.768 kHz).
- the oscillator 6 outputs the resulting oscillation signals to outside via various elements, including the IC chip 40 , the inner connection terminals 23 a, and the external terminals 27 and 28 .
- the oscillator 6 of Third Embodiment can have high reliability, and can exhibit the effects described in First Embodiment.
- the oscillator 6 may have an external module structure configuration (for example, a structure in which a vibrator having the vibrator element 1 , and the IC chip are individually mounted on a single substrate).
- the following describes a cell phone as an electronic device provided with the vibrator element described in First Embodiment.
- FIG. 7 is a schematic perspective view illustrating the cell phone of Fourth Embodiment.
- a cell phone 700 shown in FIG. 7 is configured to include the vibrator element 1 of First Embodiment as a reference clock oscillation source.
- the cell phone 700 also includes a liquid crystal display device 701 , a plurality of operation buttons 702 , an earpiece 703 , and a mouthpiece 704 .
- the vibrator element is not limited to the reference clock oscillation source of the cell phone, and may be preferably used, for example, as the reference clock oscillation source of devices such as digital books, personal computers, televisions, digital still cameras, video cameras, video recorders, navigation devices, pagers, electronic organizers, calculators, word processors, workstations, video phones, POS terminals, and devices equipped with a touch panel.
- devices such as digital books, personal computers, televisions, digital still cameras, video cameras, video recorders, navigation devices, pagers, electronic organizers, calculators, word processors, workstations, video phones, POS terminals, and devices equipped with a touch panel.
- a highly reliable electronic device having the effects described in First Embodiment can be provided.
- FIG. 8 is a schematic perspective view illustrating the automobile of Fifth Embodiment.
- An automobile 800 uses the vibrator element 1 of First Embodiment, for example, as the reference clock oscillation source of its electronically controlled devices (for example, such as an electronically controlled fuel injection device, an electronically controlled ABS device, and an electronically controlled aotocruise device).
- electronically controlled devices for example, such as an electronically controlled fuel injection device, an electronically controlled ABS device, and an electronically controlled aotocruise device.
- the automobile 800 has high reliability, and can exhibit excellent, performance with the effects described in First Embodiment.
- the vibrator element is not limited to the reference clock oscillation, source of the automobile 800 , and may foe preferably used, for example, as the reference clock oscillation source of moving objects such as self-propelled robots, self-propelled transporting machines, trains, ships, airplanes, and artificial satellites. In any case, a highly reliable moving object having the effects described in First Embodiment can be provided.
- the vibrator element When, quartz crystal is used as base material of the vibrator element, the vibrator element may be prepared from, for example, a Z-cut plate, or an X-cut plate obtained by cutting quartz crystal ores in a predetermined angle. The etching process becomes easier when Z-cut places of certain characteristics are used.
- the vibrating direction of the vibrator element is not limited to the Z-axis direction (thickness direction), and the vibrator element may vibrate, for example, in X-axis direction (the direction along the major surface) with the excitation electrodes provided on the side surfaces of the vibrating arms (the surfaces joining the major surfaces). Flexural vibration in this direction is called in-plane vibration.
- the number of vibrating arms in the vibrator element is not limited to three, and 1, 2, 4, 5, or n (n is a natural number of 6 or more) vibrating arms may be provided.
- the base portion of the vibrator element may have the same thickness as the vibrating arm. In this way. the vibrator element has a plate shape, and can be produced more easily.
Abstract
A piezoelectric film producing process includes depositing a piezoelectric body in a mixed atmosphere of N2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material.
Description
- 1. Technical Field
- The present invention relates to a piezoelectric film producing process, a vibrator element that includes a piezoelectric film produced by the process, and vibrators, oscillators, electronic devices, and moving objects that include the vibrator element.
- 2. Related Art
- A piezoelectric thin film resonator (hereinafter, referred to as “vibrator element”) is known that is configured to include a lower electrode provided on a substrate, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film, and having a region opposite the lower electrode with the piezoelectric film in between (see, for example, JP-A-2013-34130).
- The vibrator element uses aluminum nitride (hereinafter, “AlN”) for the piezoelectric film. The piezoelectric film is deposited (formed) by spattering, using Al (aluminum) as the target material (deposition material) in a mixed atmosphere of N2 (nitrogen) gas and Ar (argon) gas,
- However, because the piezoelectric film uses pure aluminum as deposition material, processes such as the deposition of the upper electrode after the AlN deposition may produce internal stress in the aluminum present at the crystal grain boundaries of the deposited AlN.
- The piezoelectric film thus involves the risk of generating stress migration, forming voids in the aluminum.
- The resulting degradation of electromechanical coupling coefficient increases the impedance of the piezoelectric film. This may cause deterioration in the function of the piezoelectric film, and the reliability (long-term reliability in particular) may suffer as a result of the progression of stress migration (e.g., void diffusion).
- This may lead to an increase in the CI (crystal impedance) value of the vibrator element that includes the piezoelectric film, and the vibration characteristics and the reliability of the vibrator element may suffer.
- An advantage of some aspects of tine invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
- A piezoelectric film producing process according to this application example includes depositing a piezoelectric film in a mixed atmosphere of N2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material.
- The piezoelectric film producing process includes depositing a piezoelectric film in a mixed atmosphere of N2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material (target material).
- Because the piezoelectric film producing process uses an Al—Cu alloy as the deposition material of the piezoelectric film, the copper exists by being dispersed in aluminum, at the crystal grain boundaries of the piezoelectric film (specifically, AlN film) deposited by sputtering (in other words, intermetallic compound (Al3Cu) is produced).
- Diffusion of aluminum at the crystal grain boundaries, and thus generation of stress migration can thus be suppressed with the piezoelectric film producing process.
- The piezoelectric film producing process can thus improve the function of the piezoelectric film, as compared to the producing process of related art (for example, JF-A-2013-34130), and can suppress stress migration to improve the reliability of the piezoelectric film.
- In the piezoelectric film producing process according to the application example described above, it is preferable that the Cu content in the Al—Cu alloy ranges from 0.25 mass % to 1.0 mass %.
- With the Cu content of 0.25 mass % to 1.0 mass % in the Al—Cu alloy, the piezoelectric film producing process can suppress Al diffusion at the crystal grain boundaries, and generation of stress migration.
- In the piezoelectric film producing process according to the application example described above, it is preferable that the Cu content in the Al—Cu alloy ranges from 0.4 mass % to 0.6 mass %.
- With the Cu content of 0.4 mass % to 0.6 mass % in the Al—Cu alloy, the piezoelectric film producing process can further suppress Al diffusion at the crystal grain boundaries, and generation of stress migration.
- In the piezoelectric film producing process according to the application example described above, it is preferable that the mixture ratio of the N2 gas and the Ar gas ranges from N2 gas 50 volume %:
Ar gas 50 volume % to N2 gas 99 volume %:Ar gas 1 volume %. - With the N2 gas and Ar gas mixture ratio of N2 gas 50 volume %:
Ar gas 50 volume % to N2 gas 99 volume %:Ar gas 1 volume %, the piezoelectric film producing process can produce a desirably functioning piezoelectric film (specifically, AlN film) by using a sputtering method. - A vibrator element according to this application example includes a base portion, and a vibrating arm extending from the base portion, wherein the vibrating arm includes a piezoelectric film that contains Cu at a crystal grain boundary.
- The vibrator element includes a base portion, and a vibrating arm extending from the base portion, and the vibrating arm includes a piezoelectric film (specifically, AIM film) that contains Cu at the crystal grain boundary. This makes it possible to suppress generation of stress migration in the piezoelectric film.
- The vibrator element can thus improve the function of the piezoelectric film as compared to related art (for example, JP-A-2013-34130), and the reliability of the piezoelectric film.
- By thus lowering the CI value, the vibrator element can improve its vibration characteristics and reliability.
- A vibrator according to this application Example includes the vibrator element according to the application example described above, and a package housing the vibrator element.
- The vibrator of this configuration, includes the vibrator element according to the application example described above, and a package housing the vibrator element. This makes it possible to provide a highly reliable vibrator having the effects described in the application example described above.
- An oscillator according to this application example includes the vibrator element according to the application example described above, and an oscillation circuit that oscillates the vibrator element.
- The oscillator of this configuration includes the vibrator element according to the application example described above, and an oscillation circuit that oscillates the vibrator element. This makes it possible to provide a highly reliable oscillator having the effects described in the application example described above.
- An electronic device according to this application example includes the vibrator element according to the application example described above.
- The electronic device of this configuration includes the vibrator element according to the application example described above. This makes it possible to provide a highly reliable electronic device having the effects described in the application example described above.
- A moving object according to this application example includes the vibrator element according to the application example described above.
- The moving object of this configuration includes the vibrator element according to the application example described above. This makes it possible to provide a highly reliable moving object having the effects described in the application example described above.
- The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
-
FIGS. 1A and 1B are schematic diagrams illustrating a schematic structure of a vibrator element of First Embodiment, in whichFIG. 1A is a plan view, andFIG. 1B is a cross sectional view taken at line A-A ofFIG. 1A . -
FIG. 2 is a cross sectional view taken at line B-B ofFIG. 1A , shown alongside with a wiring diagram of each excitation electrode. -
FIG. 3 is a schematic diagram explaining a piezoelectric body producing process. -
FIG. 4 is a diagram representing piezoelectric body deposition conditions, and corresponding evaluation results. -
FIGS. 5A and 5B are schematic diagrams illustrating a schematic structure of a vibrator of Second Embodiment, in whichFIG. 5A is a plan view as viewed from the lid (cap) side, andFIG. 5B is a cross sectional view taken at line C-C ofFIG. 5A . -
FIGS. 6A and 6B are schematic diagrams illustrating a schematic structure of an oscillator of Third Embodiment, in whichFIG. 6A is a plan view as viewed from the lid side, andFIG. 6B is a cross sectional, view taken at line C-C ofFIG. 6A . -
FIG. 7 is a schematic perspective view of a cell phone of Fourth Embodiment. -
FIG. 8 is a schematic perspective view of an automobile of Fifth Embodiment. - Embodiments of specific implementation of the invention are described below with reference to the accompanying drawings.
- A vibrator element that uses a Si (silicon) base material is described as an example of the vibrator element.
-
FIGS. 1A and 1B are schematic diagrams illustrating a schematic structure of the vibrator element of First Embodiment.FIG. 1A is a plan view, andFIG. 1B is a cross sectional view taken at line A-A ofFIG. 1A . Wires are omitted, and the dimensional ratio of each constituting element differs from the actual dimension ratios. -
FIG. 2 is a cross sectional view taken at line B-B ofFIG. 1A , shown alongside with a wiring diagram of each excitation electrode. - In the drawings, the X, Y, and Z axes are coordinate axes that are orthogonal to each other.
- As illustrated in
FIGS. 1A and 1B , the base material of avibrator element 1 includes abase portion 10, and three vibratingarms base portion 10 in Y-axis direction. In the present embodiment, a Si substrate (for example, a SOI-, or Poly-Si-deposited substrate) is used for the three vibratingarms base portion 10. - The vibrating
arms arms excitation electrodes excitation electrodes major surfaces major surface 10 a) that lie on the plane (XY plane) specified by X axis and Y axis, - The
excitation electrodes major surface 10 a) in the vibratingarras major surface 10 a (the direction of arrow inFIG. 1B ). - The
base portion 10, the vibratingarms excitation electrodes - The
excitation electrodes first electrodes 12 a 1, 12b major surface 10 a side,second electrodes 12 a 2, 12b first electrodes 12 a 1, 12b piezoelectric body 13 disposed as a piezoelectric film between thefirst electrodes b second electrodes 12 a 2, 12b film 14 provided between thefirst electrodes 12 a 1, 12b piezoelectric body 13. The insulatingfilm 14 may be omitted. - The
first electrodes 12 a 1, 12b second electrodes 12 a 2, 12b excitation electrodes piezoelectric body 13 uses a film that contains AlN (aluminum nitride). The insulatingfilm 14 uses a film that contains amorphous SiO2 (silicon dioxide). - The
piezoelectric body 13 is formed (deposited) by sputtering, using an Al—Cu alloy as deposition material (target material), as will be described later in detail. - For desirable vibration characteristics of the
vibration reed 1, thefirst electrodes 12 a 1, 12b second electrodes 12 a 2, 12b excitation electrodes piezoelectric body 13 has a thickness of preferably about 200 nm to 400 nm, and the insulatingfilm 14 has a thickness of preferably about 10 nm. - The
first electrodes 12 a 1, 12b second electrodes 12 a 2, 12b - It is preferable for efficient vibration characteristics that the
excitation electrodes arms arms - As illustrated in
FIG. 1B , thebase portion 10 is thicker than the vibratingarms - The
base portion 10 has fixingportions portions major surface 10 b side of thebase portion 10 at the both ends relative to X-axis direction, as indicated by long dashed double-short dashed line inFIG. 1A , Preferably, the fixingportions base portion 10 opposite the vibratingarms - The operation of the
vibrator element 1 is described below. - As illustrated in
FIG. 2 , thefirst electrodes 12 a 1, 12b second electrodes 12 a 2, 12b excitation electrodes vibrator element 1 are connected to an alternate current power supply by crossed wires, and a driving alternating voltage is applied to these electrodes. - Specifically, the
first electrode 12 a 1 of the vibratingarm 11 a, thesecond electrode 12b 2 of the vibratingarm 11 b, and the first electrode 12 cl of the vibratingarm 11 c are connected to bring these electrodes at the same potential. Thesecond electrode 12 a 2 of the vibratingarm 11 a, thefirst electrode 12b 1 of the vibratingarm 11 b, and thesecond electrode 12c 2 of the vibratingarm 11 c are connected to bring these electrodes at the same potential. - Applying alternating voltage between the
first electrodes 12 a 1, 12b second electrodes 12 a 2, 12b first electrodes 12 a 1, 12b second electrodes 12 a 2, 12b piezoelectric body 13 polarizes under the generated electric field, and the reverse piezoelectric effect produces strains in thepiezoelectric body 13, causing thepiezoelectric body 13 to expand and contract in Y-axis direction. - The
vibrator element 1 is configured so that the direction of the electric field generated by the crossed wires in theexcitation electrodes excitation electrode 12 b, and thepiezoelectric body 13 expands and contracts in opposite ways between the vibratingarms arm 11 b. - Specifically, the
piezoelectric body 13 of the vibratingarm 11 b contracts when thepiezoelectric bodies 13 of the vibratingarms 11 a and lie expand, and thepiezoelectric body 13 of the vibrating arm lib expands when thepiezoelectric bodies 13 of the vibratingarms 11 a and lie contract. - With such expansion and contraction of the
piezoelectric bodies 13 in thevibrator element 1, the vibratingarms - By repeating these movements, the vibrating
arms vibrator element 1 undergo flexural vibration (antiplane vibration) in Z-axis direction. Here, flexural vibration occurs in reverse direction (reverse phase) between the adjacent vibrating arms (between 11 a and 11 b, and between 11 b and 11 c in this embodiment). - A process for producing the
piezoelectric body 13 as a constituting element of theexcitation electrodes vibrator element 1 is described below (piezoelectric film producing process). -
FIG. 3 is a schematic diagram explaining the piezoelectric body producing process. - As illustrated in
FIG. 3 , thevibrator element 1 with thefirst electrodes 12 a 1, 12b film 14 is set on abase mount 51 in avacuum chamber 50. - Thereafter, N2 (nitrogen) gas and Ar (argon) gas are introduced into the
vacuum chamber 50 with a vacuum pump or the like (not illustrated) to produce a mixed atmosphere of N2 gas and Ar gas. - Here, the pressure inside the
vacuum chamber 50 is preferably about 0.53 Pa (4 mTorr). The N2 gas and Ar gas mixture ratio preferably ranges from N2 gas 50 volume %:Ar gas 50 volume % to N2 gas 99 volume %:Ar gas 1 volume %. - The
vibrator element 1 is preferably kept at ordinary temperature. - An Al—Cu alloy 52 as deposition material (target material) is then set on a
target mount 53. - The Cu content in the Al—Cu alloy is preferably 0.25 mass % to 1.0 mass %, more preferably 0.4 mass % to 0.6 mass %.
- Thereafter, a
power supply 54 applies voltage (for example, about 100 V to 1,000 V) by using a sputtering method (reactive sputtering), using the Al—Cu. alloy 52 as cathode, and thevibrator element 1 as anode. - In response, the ion atoms in the mixed gas of it gas and Ar gas sputter the surface of the Al—Cu alloy 52, and the particles (atoms and molecules) jumped out of the Al—Cu alloy 52 deposit and fix to the
vibrator element 1, covering the insulatingfilm 14. This deposits (forms) the piezoelectric body 13 (AlN film). - The
piezoelectric body 13 is then patterned into a desired shape by using methods such as photolithography, and etching. - The
piezoelectric body 13 can be obtained in this manner after these steps. - This is followed by formation of the
second electrodes 12 a 2, 12b piezoelectric body 13 by using methods such as sputtering, photolithography, and etching, and thevibrator element 1 shown inFIGS. 1A and 1B , andFIG. 2 is obtained. - As described above, the process for producing the
piezoelectric body 13 of the present embodiment (hereinafter, “piezoelectric film producing process”) includes depositing the piezoelectric body 13 (piezoelectric film) in a mixed atmosphere of N2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material (target material). - Because the piezoelectric film producing process uses the Al—Cu alloy as deposition material for the deposition of the
piezoelectric body 13, the copper exists by being dispersed in aluminum at the crystal grain boundaries of the piezoelectric body 13 (specifically, AlN film) deposited as the piezoelectric film by sputtering (in other words, intermetallic compound (Al3Cu) is produced). - Diffusion of aluminum at the crystal grain boundaries of the
piezoelectric body 13, and thus generation of stress migration can thus be suppressed with the piezoelectric film producing process. - The piezoelectric film producing process can thus improve the function of the
piezoelectric body 13 as compared to the producing process of related art (for example, JP-A-2013-34130), and can suppress stress migration to improve the reliability of thepiezoelectric body 13. - Further, because the Cu content in the Al—Cu alloy ranges from 0.25 mass % to 1.0 mass %, the piezoelectric film producing process can suppress Al diffusion at the crystal grain boundaries of the
piezoelectric body 13, and thus generation of stress migration. - Further, because the Cu content in the Al—Cu alloy ranges from 0.4 mass % to 0.6 mass %, the piezoelectric film producing process can further suppress Al diffusion at the crystal grain boundaries of the
piezoelectric body 13, and thus generation of stress migration. - Further, because the N2 gas and Ar gas mixture ratio ranges from N2 gas 50 volume %:
Ar gas 50 volume % to N2 gas 99 volume %:Ar gas 1 volume %, the piezoelectric body 13 (specifically, AlN film) produced by the piezoelectric film producing process by sputtering can be desirably functional. - The following describes the foregoing process in greater detail with reference to the drawings.
-
FIG. 4 is a diagram representing piezoelectric body deposition conditions (N2 gas and Ar gas mixture ratios), and corresponding evaluation results for each sample. - The sheet resistance of the
piezoelectric body 13 should, be about at least 30,000 Ω□ (ohm square), and a 3- to 4-degree angle is considered sufficient for FWHM (half width of the peak in the X-ray diffraction orientation evaluation of the piezoelectric body 13). - In the evaluation results, “Good” and “Acceptable” mean that the piezoelectric body is practically satisfactory, and “Poor” means practically unsatisfactory. The Cu content in the deposition material Al—Cu alloy of the
piezoelectric body 13 is 0.5 mass %. - As shown in
FIG. 4 , sample No. 1 (N2 gas 99 volume %:Ar gas 1 volume %; in the following, the unit “volume %” will be omitted) has a sheet resistance of infinity Ω□, and an FWHM of 3.18 degrees, and the evaluation result is “Good”. - Sample No. 2 (N2 gas 80:Ar gas 20) has a sheet resistance of infinity Ω□, and an FWHM of 3.42 degrees, and the evaluation result is “Good”.
- Sample No. 3 (N2 gas 70:Ar gas 30) has a sheet resistance of infinity Ω□ and an FWHM of 3.43 degrees, and the evaluation result is “Good”.
- Sample No. 4 (N2 gas 60:Ar gas 40) has a sheet resistance of infinity Ω□, and an FWHM of 3.69 degrees, and the evaluation result is “Good”.
- Sample No. 5 gas 50: Ar gas 50) has a sheet resistance of 31146 Ω□, and an FWHM of 3.50 degrees, and the evaluation result is “Acceptable” (“Acceptable” because of the slightly smaller sheet resistance margin).
- On the other hand, sample ho. 6 (N2 gas 40 :Ar gas 60) has a sheet resistance of 0.3100 Ω□, and the FWHM is incalculable (the peak is unclear, and the half width cannot be calculated), and the evaluation result is “Poor”.
- Sample No. 7 (N2 gas 10:Ar gas 90) has a sheet resistance of 0.0621 Ω□, and the FWHM is incalculable (the peak is unclear, and the half width cannot be calculated), and the evaluation result is “Poor”.
- These evaluation results of the samples support that the
piezoelectric body 13 produced by the piezoelectric film producing process using sputtering can desirably function (at practically satisfactory levels) when the N2 gas and Ar gas mixture ratio ranges from N2 gas 50 volume %:Ar gas 50 volumes to N2 gas 99 volume %:Ar gas 1 volume %. - As described above, the
vibrator element 1 of the present embodiment includes thebase portion 10, and the vibratingarms base portion 10, and thepiezoelectric body 13 provided for the vibratingarms piezoelectric body 13. - The
vibrator element 1 can thus improve the function of the piezoelectric body 13 (specifically, for example, expansion and contraction capability under applied electric field) as compared to related art (for example, JP-A-2013-34130), and the reliability of thepiezoelectric body 13. - By thus lowering the CI value, the
vibrator element 1 can improve its vibration characteristics and reliability. - The
vibrator element 1 may include a SiO2-containing film between themajor surface 10 a and thefirst electrodes 12 a 1, 12b arms - In this case, the SiO2-containing film in the
vibrator element 1 functions as a temperature characteristics correction film for the vibratingarms - Specifically, the slope of the frequency-temperature characteristics of one SiO2-containing film in the
vibrator element 1 corrects (cancels) the slope of the frequency-temperature characteristics of the vibratingarms - In this way, the
vibrator element 1 can suppress frequency fluctuations due to temperature changes, and can improve the frequency-temperature characteristics. - In the
vibrator element 1, the SiO2-containing film may be provided on the opposite side (themajor surface 10 b side) of thefirst electrodes 12 a 1, 12b major surface 10 a side) of the vibratingarms - The effect obtained as above also can be obtained with this configuration of the
vibrator element 1. - The following describes a vibrator provided, with the vibrator element described in First Embodiment.
-
FIGS. 5A and 5B are schematic diagrams illustrating a schematic structure of the vibrator of Second Embodiment.FIG. 5A is a plan view as viewed from the lid (cap) side, andFIG. 5B is a cross sectional view taken at line C-C ofFIG. 5A . The lid is emitted, in the plan view. Wires are also omitted. - Common elements already described in First Embodiment are given the same reference numerals, and detailed explanations thereof are omitted, Descriptions will primarily focus on differences from First Embodiment.
- As illustrated in
FIGS. 5A and 5B , avibrator 5 includes thevibrator element 1 described in First Embodiment, and apackage 20 housing thevibrator element 1. - The
package 20 is substantially cuboid in shape, and includes apackage base 21 having a substantially rectangular planar shape with a depression, and a plate-shapedlid 22 having a substantially rectangular planar shape covering the depression of she package base 21. - The
package base 21 uses, for example, materials such as an aluminum, oxide sintered body obtained by laminating and sintering a molded ceramic green sheet. Other examples include crystals, glass, and Si. - The
lid 22 uses the same material used for thepackage base 21, or metals such as kovar, and 42 alloy. - The
package base 21 includesinner terminals - The
inner terminals interconnection electrodes base portion 10 of thevibrator element 1. Theinterconnection electrodes vibrator element 1 via wires (not illustrated). - For example, in the wiring shown in
FIG. 2 , the wire on one side of the alternate current power supply is connected to theinterconnection electrode 18 a, and the wire on the other side of the alternate current power supply is connected to theinterconnection electrode 18 b. - A pair of
external terminals inner bottom surface 23; the bottom surface on the outer side) 26 of thepackage base 21. - The
external terminals inner terminals external terminal 27 is connected to theinner terminal 24, and theexternal terminal 28 is connected to theinner terminal 25. - The
inner terminals external terminals - In the
vibrator 5, thefiling portions base portion 10 of thevibrator element 1 are fixed to theinner bottom surface 23 of thepackage base 21 via an adhesive 30 of materials such as epoxy, silicone, and polyimide. - In the
vibrator 5, theinterconnection electrodes vibrator element 1 are connected to theinner terminals metal wires 31 of materials such as Au and Al. - In the
vibrator 5, inside of thepackage 20 is sealed air-tightly by bonding thepackage base 21 and thelid 22 to each other with abonding member 29 such as a seam ring, low-melting-point glass, and an adhesive after covering the depression of thepackage base 21 with thelid 22 with thevibrator element 1 being connected to theinner terminals package base 21. - Inside of the
package 20 is kept in a reduced pressure state (high vacuum state), or charged with inert gas such as N2, He (helium), and Ar. - The package may be configured from, for example, a plate-shaped package base, and a depressed lid. The package may have a depression in both the package base and the lid,
- The
base portion 10 of thevibrator element 1 may be fixed at portions other than the fixingportions portion 10 c and the fixingportion 10 d to each other, instead of using the fixingportions - In this way, because the
vibrator element 1 is fixed at a single point, distortions in thebase portion 10 due to the generated, thermal stress in the fixing portion can be suppressed. - Under the applied drive signal (alternating voltage) to the excitation electrodes (e.g., 12 b) via the external,
terminals inner terminals metal wires 31, and theinterconnection electrodes vibrator element 1 in thevibrator 5 oscillate (resonate) in thickness direction (direction of arrow inFIG. 5B ) at a predetermined frequency (for example, about 32.768 kHz). - By the provision of the
vibrator element 1, thevibrator 5 of Second Embodiment can have high reliability, and can exhibit the effects described in First Embodiment. - The following describes an oscillator provided with the vibrator element described in First Embodiment.
-
FIGS. 6A and 6B are schematic diagrams illustrating a schematic structure of the oscillator of Third Embodiment.FIG. 6A is a plan view as viewed from the lid side, andFIG. 6B is a cross sectional view taken at line C-C ofFIG. 6A . The lid, and some of other constituting elements are omitted in the plan view. Wires are also omitted. - Common elements already described in First and Second Embodiments are given the same reference numerals, and detailed explanations thereof are omitted. Descriptions will primarily focus on differences from First and Second Embodiment.
- As illustrated in
FIGS. 6A and 6B , an oscillator 6 includes thevibrator element 1 described in Burst Embodiment, anIC chip 40 provided as an oscillation circuit for oscillating thevibrator element 1, and apackage 20 housing thevibrator element 1 and sheIC chip 40. -
Inner connection terminals 23 a are provided on aninner bottom surface 23 of apackage base 21. - The
IC chip 40 installing the oscillation circuit is fixed to theinner bottom surface 23 of thepackage base 21 with an adhesive or the like (not illustrated). - The
IC chip 40 is connected to theinner connection terminals 23 a as interconnection pads (not illustrated), usingmetal wires 41 of materials such as Au and Al. - The
inner connection terminals 23 a are formed of a laminated metal film obtained by laminating coating materials such as Ni and Au on a metallization layer such as W and Mo, using a method such as plating, and are connected to, for example, theexternal terminals inner terminals package 20 via inner wires (not illustrated). - Instead of the wire bonding using the
metal wires 41, the interconnection pads of theIC chip 40 and theinner connection terminals 23 a may be connected to each other by using, for example, an interconnection method based on flip-chip mounting, by flipping theIC chip 40. - Under the applied drive signal from the
IC chip 40 to the excitation electrodes (e.g., 12 b) via theinner connection terminals 23 a, theinner terminals metal wires 31, and she interconnectionelectrodes vibrator element 1 in the oscillator 6 oscillate (resonate) at a predetermined frequency (for example, about 32.768 kHz). - The oscillator 6 outputs the resulting oscillation signals to outside via various elements, including the
IC chip 40, theinner connection terminals 23 a, and theexternal terminals - By the provision of the
vibrator element 1, the oscillator 6 of Third Embodiment can have high reliability, and can exhibit the effects described in First Embodiment. - Instead of using the
IC chip 40 built into thepackage 20, the oscillator 6 may have an external module structure configuration (for example, a structure in which a vibrator having thevibrator element 1, and the IC chip are individually mounted on a single substrate). - The following describes a cell phone as an electronic device provided with the vibrator element described in First Embodiment.
-
FIG. 7 is a schematic perspective view illustrating the cell phone of Fourth Embodiment. - A
cell phone 700 shown inFIG. 7 is configured to include thevibrator element 1 of First Embodiment as a reference clock oscillation source. Thecell phone 700 also includes a liquidcrystal display device 701, a plurality ofoperation buttons 702, anearpiece 703, and amouthpiece 704. - The vibrator element is not limited to the reference clock oscillation source of the cell phone, and may be preferably used, for example, as the reference clock oscillation source of devices such as digital books, personal computers, televisions, digital still cameras, video cameras, video recorders, navigation devices, pagers, electronic organizers, calculators, word processors, workstations, video phones, POS terminals, and devices equipped with a touch panel. In any case, a highly reliable electronic device having the effects described in First Embodiment can be provided.
- The following describes an automobile as an example of a moving object provided with the vibrator element described in First Embodiment.
-
FIG. 8 is a schematic perspective view illustrating the automobile of Fifth Embodiment. - An
automobile 800 uses thevibrator element 1 of First Embodiment, for example, as the reference clock oscillation source of its electronically controlled devices (for example, such as an electronically controlled fuel injection device, an electronically controlled ABS device, and an electronically controlled aotocruise device). - By the provision of the
vibrator element 1, theautomobile 800 has high reliability, and can exhibit excellent, performance with the effects described in First Embodiment. - The vibrator element is not limited to the reference clock oscillation, source of the
automobile 800, and may foe preferably used, for example, as the reference clock oscillation source of moving objects such as self-propelled robots, self-propelled transporting machines, trains, ships, airplanes, and artificial satellites. In any case, a highly reliable moving object having the effects described in First Embodiment can be provided. - When, quartz crystal is used as base material of the vibrator element, the vibrator element may be prepared from, for example, a Z-cut plate, or an X-cut plate obtained by cutting quartz crystal ores in a predetermined angle. The etching process becomes easier when Z-cut places of certain characteristics are used.
- The vibrating direction of the vibrator element is not limited to the Z-axis direction (thickness direction), and the vibrator element may vibrate, for example, in X-axis direction (the direction along the major surface) with the excitation electrodes provided on the side surfaces of the vibrating arms (the surfaces joining the major surfaces). Flexural vibration in this direction is called in-plane vibration.
- The number of vibrating arms in the vibrator element is not limited to three, and 1, 2, 4, 5, or n (n is a natural number of 6 or more) vibrating arms may be provided.
- The base portion of the vibrator element may have the same thickness as the vibrating arm. In this way. the vibrator element has a plate shape, and can be produced more easily.
- The entire disclosure of Japanese Patent Application No. 2013-151378, filed Jul. 22, 2013 is expressly incorporated by reference herein.
Claims (9)
1. A piezoelectric film producing process comprising depositing a piezoelectric film in a mixed atmosphere of N2 gas and Ar gas by using a sputtering method, using an Al—Cu alloy as deposition material.
2. The process according to claim 1 , wherein the Cu content in the deposition material Al—Cu alloy ranges from 0.25 mass % to 1.0 mass %.
3. The process according to claim 1 , wherein the Cu content in the deposition material Al—Cu alloy ranges from 0.4 mass % to 0.6 mass %.
4. The process according to claim 1 , wherein the mixture ratio of the N2 gas and the Ar gas ranges from N2 gas 50 volume %:Ar gas 50 volume % to N2 gas 99 volume %:Ar gas 1 volume %.
5. A vibrator element comprising a base portion, and a vibrating arm extending from the base portion,
wherein the vibrating arm includes a piezoelectric film that contains Cu at a crystal grain boundary.
6. A vibrator comprising:
the vibrator element of claim 5 ; and
a package housing the vibrator element.
7. An oscillator comprising:
the vibrator element of claim 5 ; and
an oscillation circuit that oscillates the vibrator element.
8. An electronic device comprising the vibrator element of claim 5 .
9. A moving object comprising the vibrator element of claim 5 .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/727,215 US9461617B2 (en) | 2013-07-22 | 2015-06-01 | Piezoelectric film producing process, vibrator element, vibrator, oscillator, electronic device, and moving object |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2013151378A JP6205937B2 (en) | 2013-07-22 | 2013-07-22 | Piezoelectric film manufacturing method, vibrator manufacturing method, vibrator element, vibrator, oscillator, electronic device, and moving body |
JP2013-151378 | 2013-07-22 |
Related Child Applications (1)
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US14/727,215 Division US9461617B2 (en) | 2013-07-22 | 2015-06-01 | Piezoelectric film producing process, vibrator element, vibrator, oscillator, electronic device, and moving object |
Publications (1)
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US20150022274A1 true US20150022274A1 (en) | 2015-01-22 |
Family
ID=52343119
Family Applications (2)
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US14/330,626 Abandoned US20150022274A1 (en) | 2013-07-22 | 2014-07-14 | Piezoelectric film producing process, vibrator element, vibrator, oscillator, electronic device, and moving object |
US14/727,215 Active US9461617B2 (en) | 2013-07-22 | 2015-06-01 | Piezoelectric film producing process, vibrator element, vibrator, oscillator, electronic device, and moving object |
Family Applications After (1)
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US14/727,215 Active US9461617B2 (en) | 2013-07-22 | 2015-06-01 | Piezoelectric film producing process, vibrator element, vibrator, oscillator, electronic device, and moving object |
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US (2) | US20150022274A1 (en) |
JP (1) | JP6205937B2 (en) |
CN (2) | CN104333338A (en) |
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US20150349746A1 (en) * | 2014-05-29 | 2015-12-03 | Seiko Epson Corporation | Electronic device, electronic apparatus, and moving object |
CN110047148A (en) * | 2019-04-10 | 2019-07-23 | 珠海梅西互动技术有限公司 | A kind of the emulation interactive visual system and implementation method of virtual robot work station |
US10663432B2 (en) * | 2018-04-10 | 2020-05-26 | Tianma Japan, Ltd. | Gas sensor and gas detection method |
US10756670B2 (en) * | 2016-12-19 | 2020-08-25 | Seiko Epson Corporation | Resonator, oscillator, electronic apparatus, and vehicle |
US20210203304A1 (en) * | 2018-09-13 | 2021-07-01 | Murata Manufacturing Co., Ltd. | Resonator and resonance device including same |
US11482662B2 (en) * | 2018-05-28 | 2022-10-25 | Taiyo Yuden Co., Ltd. | Aluminum nitride film, piezoelectric device, resonator, filter, and multiplexer |
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CN110047148A (en) * | 2019-04-10 | 2019-07-23 | 珠海梅西互动技术有限公司 | A kind of the emulation interactive visual system and implementation method of virtual robot work station |
Also Published As
Publication number | Publication date |
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JP2015023483A (en) | 2015-02-02 |
CN104333338A (en) | 2015-02-04 |
JP6205937B2 (en) | 2017-10-04 |
CN110724917A (en) | 2020-01-24 |
US9461617B2 (en) | 2016-10-04 |
US20150295558A1 (en) | 2015-10-15 |
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