WO2018203430A1 - 弾性波素子およびその製造方法 - Google Patents
弾性波素子およびその製造方法 Download PDFInfo
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- WO2018203430A1 WO2018203430A1 PCT/JP2018/005882 JP2018005882W WO2018203430A1 WO 2018203430 A1 WO2018203430 A1 WO 2018203430A1 JP 2018005882 W JP2018005882 W JP 2018005882W WO 2018203430 A1 WO2018203430 A1 WO 2018203430A1
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- piezoelectric material
- substrate
- bonding
- material substrate
- acoustic wave
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- 238000000034 method Methods 0.000 title claims description 31
- 238000004519 manufacturing process Methods 0.000 title claims description 5
- 239000000758 substrate Substances 0.000 claims abstract description 217
- 239000000463 material Substances 0.000 claims abstract description 147
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 43
- 239000010453 quartz Substances 0.000 claims description 26
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- 239000010703 silicon Substances 0.000 claims description 15
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 claims description 7
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 claims description 7
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 5
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Inorganic materials O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 claims description 5
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 claims description 5
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 5
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 claims description 4
- 229910052863 mullite Inorganic materials 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
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- 238000010897 surface acoustic wave method Methods 0.000 description 22
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 19
- 229910052814 silicon oxide Inorganic materials 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 10
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- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 5
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000000452 restraining effect Effects 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
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- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
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- 238000000206 photolithography Methods 0.000 description 1
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- 150000003377 silicon compounds Chemical class 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
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- 229910052715 tantalum Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- RIUWBIIVUYSTCN-UHFFFAOYSA-N trilithium borate Chemical compound [Li+].[Li+].[Li+].[O-]B([O-])[O-] RIUWBIIVUYSTCN-UHFFFAOYSA-N 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
- H03H9/02834—Means for compensation or elimination of undesirable effects of temperature influence
-
- 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
- H03H3/10—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 for obtaining desired frequency or temperature coefficient
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/058—Holders; Supports for surface acoustic wave devices
- H03H9/0585—Holders; Supports for surface acoustic wave devices consisting of an adhesive layer
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14538—Formation
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
-
- 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
- H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
- H10N30/072—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies
- H10N30/073—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies by fusion of metals or by adhesives
-
- 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
- H10N30/704—Piezoelectric or electrostrictive devices based on piezoelectric or electrostrictive films or coatings
- H10N30/706—Piezoelectric or electrostrictive devices based on piezoelectric or electrostrictive films or coatings characterised by the underlying bases, e.g. substrates
- H10N30/708—Intermediate layers, e.g. barrier, adhesion or growth control buffer layers
Definitions
- the present invention relates to an acoustic wave device and a method for manufacturing the same.
- acoustic wave devices that can function as filter elements and oscillators used in mobile phones, etc., and acoustic wave devices such as Lamb wave elements using piezoelectric thin films and thin film resonators (FBAR: FilmFiBulk Acoustic Resonator) are known.
- FBAR FilmFiBulk Acoustic Resonator
- a surface acoustic wave device a device in which a support substrate and a piezoelectric material substrate that propagates a surface acoustic wave are bonded together and a comb-shaped electrode capable of exciting the surface acoustic wave is provided on the surface of the piezoelectric material substrate is known. Yes.
- a silicon oxide film is formed on the surface of the piezoelectric material substrate, and the piezoelectric material substrate and the silicon substrate are directly bonded via the silicon oxide film.
- Patent Document 1 the surface of the silicon oxide film and the surface of the silicon substrate are irradiated with a plasma beam to activate the surfaces and perform direct bonding (plasma activation method).
- Patent Document 2 describes that the temperature characteristic of the frequency of an acoustic wave element is improved by bonding a piezoelectric material substrate such as lithium tantalate to another piezoelectric material substrate. . In this case, it is also described that generation of an unjoined portion is suppressed by interposing silicon or a silicon compound between two piezoelectric material substrates.
- An object of the present invention is to provide an acoustic wave device having a structure capable of further improving the propagation characteristics of acoustic waves and the temperature characteristics of frequency in an acoustic wave device in which a piezoelectric material substrate and a support substrate are bonded via a bonding layer. It is.
- the present invention provides a piezoelectric material substrate, Electrodes on a piezoelectric material substrate, An acoustic wave device comprising a support substrate, and a bonding layer for bonding the piezoelectric material substrate and the support substrate,
- the bonding layer is made of quartz, and relates to an acoustic wave device.
- the present invention also provides: A process of bonding a piezoelectric material substrate and a crystal plate; Processing the crystal plate to form a bonding layer;
- the present invention relates to a method for manufacturing an acoustic wave element, comprising the steps of bonding the bonding layer and a support substrate, and forming an electrode on the piezoelectric material substrate.
- the present inventor further studied the reason why there is a limit to the improvement of the propagation loss and the temperature characteristic of the frequency in the acoustic wave elements as described in Patent Documents 1 and 2. That is, when a silicon oxide film is formed on a piezoelectric material substrate, the silicon oxide film does not grow epitaxially and becomes amorphous, and the crystallinity is low. Therefore, an elastic wave leaks to the silicon oxide film side and propagation loss occurs. In addition, since the restraining force by the support substrate is reduced, it has been found that the temperature change of the frequency tends to increase.
- an acoustic wave element when an acoustic wave element is manufactured by bonding a piezoelectric material substrate to another piezoelectric material substrate (for example, a quartz substrate), the acoustic wave leaks into the quartz substrate and is absorbed, so that the insertion loss It has been found that it is difficult to reduce the frequency, and the restraining force of the piezoelectric material substrate by the quartz substrate is also limited, so that it is difficult to improve the temperature change of the frequency.
- the piezoelectric material substrate is bonded to a separate support substrate via a bonding layer made of quartz.
- Quartz is a single crystal and the bonding layer made of quartz is bonded to a separate support substrate, so that leakage of elastic waves from the piezoelectric material substrate to the bonding layer is suppressed.
- the piezoelectric material substrate can be restrained by the support substrate, the temperature characteristic of the frequency can be reduced at the same time.
- (A) is a front view which shows the piezoelectric material board
- (b) is a front view which shows the joined body of the piezoelectric material board
- (A) shows a state where the piezoelectric material substrate 2 and the support substrate 3 are joined,
- (b) shows a state where the piezoelectric material substrate 2 is processed and thinned, and (c) shows the acoustic wave element 5.
- (A) is a front view showing the piezoelectric material substrate 2, the crystal plate 1 and the piezoelectric material substrate side intermediate layer 6, and (b) shows a joined body of the piezoelectric material substrate 2 and the crystal plate 1. It is a front view, (c) shows the state which processed the crystal plate 1 and formed 1 A of joining layers.
- (A) shows a state where the piezoelectric material substrate 2 and the support substrate 3 are joined,
- (b) shows a state where the piezoelectric material substrate 2 is processed and thinned, and
- (c) shows an acoustic wave element 5A. Indicates.
- (A) shows the piezoelectric material substrate 2, the support substrate 3, and the silicon oxide films 8 and 9, and (b) shows a state in which the piezoelectric material substrate 2 and the support substrate 3 are bonded via the bonding layer 10.
- (C) shows the acoustic wave element 15 of the comparative example.
- a piezoelectric material substrate 2 and a crystal plate 1 are prepared.
- the main surface 2a of the piezoelectric material substrate 2 is a bonding surface
- the main surface 1a of the crystal plate 1 is a bonding surface.
- the piezoelectric material substrate 2 and the crystal plate 1 are directly joined.
- the main surface 1b of the quartz plate 1 is processed to have a predetermined thickness to obtain a bonding layer 1A made of quartz.
- the bonding surface 3a of the separate support substrate 3 is opposed to the bonding surface 1c of the bonding layer 1A.
- 3 b is the bottom surface of the support substrate 3.
- electrodes may be provided on the piezoelectric material substrate 2, but preferably, as shown in FIG. 2B, the main surface 2 b of the piezoelectric material substrate 2 is processed to provide the piezoelectric material substrate 2.
- FIG. 2C is a processed surface.
- a predetermined electrode 4 is formed on the processed surface 2c of the piezoelectric material substrate 2A, and the acoustic wave element 5 can be obtained.
- the piezoelectric material substrate 2 and the crystal plate 1 are directly bonded, and the bonding layer 1A and the support substrate 3 are directly bonded.
- a piezoelectric material substrate-side intermediate layer can be provided between the piezoelectric material substrate 2 and the bonding layer 1A, and a support substrate-side intermediate layer can be provided between the support substrate 3 and the bonding layer 1A.
- These intermediate layers can further improve the bonding strength. 3 and 4 relate to this embodiment.
- a piezoelectric material substrate 2 and a crystal plate 1 are prepared.
- a piezoelectric material substrate-side intermediate layer 6 is formed on the bonding surface 1 a of the crystal plate 1.
- the bonding surface 2a of the piezoelectric material substrate 2 and the surface 6a of the piezoelectric material substrate side intermediate layer 6 are bonded.
- the piezoelectric material substrate side intermediate layer 6 is provided on the crystal plate 1, but the piezoelectric material substrate side intermediate layer 6 may be provided on the bonding surface 2 a of the piezoelectric material substrate 2.
- a method for forming the piezoelectric material substrate side intermediate layer 6 it is possible to form an intermediate layer on each of the crystal plate 1 and the piezoelectric material substrate 2 and to join both the intermediate layers together.
- the quartz plate 1 is processed to a predetermined thickness to obtain a bonding layer 1A made of quartz.
- the support substrate side intermediate layer 7 is further provided on the bonding surface 1c of the bonding layer 1A.
- the bonding surface 3 a of the separate support substrate 3 is opposed to the bonding surface 7 a of the support substrate side intermediate layer 7.
- 3 b is the bottom surface of the support substrate 3.
- the bonding surface 3a of the support substrate 3 and the bonding surface 7a of the intermediate layer 7 are directly bonded.
- the support substrate side intermediate layer 7 is provided on the bonding layer 1 ⁇ / b> A made of quartz, but the support substrate side intermediate layer 7 may be provided on the bonding surface 3 a of the support substrate 3.
- an intermediate layer can be formed on each of the bonding layer 1 ⁇ / b> A made of quartz and the support substrate 3, and both intermediate layers can be bonded and integrated.
- an electrode may be provided on the piezoelectric material substrate 2, but preferably, the main surface 2b of the piezoelectric material substrate 2 is processed as shown in FIG. 4B.
- the substrate 2 is thinned to obtain a thin piezoelectric material substrate 2A.
- 2c is a processed surface.
- a predetermined electrode 4 is formed on the processed surface 2c of the piezoelectric material substrate 2A, and an acoustic wave element 5A can be obtained.
- the acoustic wave element 5A includes the piezoelectric material substrate-side intermediate layer 6 and the support substrate-side intermediate layer 7.
- the present invention is not limited thereto, and only one of the intermediate layers (only the piezoelectric material substrate side intermediate layer 6 or the support substrate side intermediate layer 7) may be provided.
- a surface acoustic wave device As the acoustic wave elements 5 and 5A, a surface acoustic wave device, a Lamb wave element, a thin film resonator (FBAR), and the like are known.
- a surface acoustic wave device has an IDT (Interdigital Transducer) electrode (also referred to as a comb-shaped electrode or a comb-shaped electrode) for exciting surface acoustic waves on the surface of a piezoelectric material substrate and an output side for receiving surface acoustic waves. IDT electrodes are provided.
- IDT Interdigital Transducer
- a metal film may be provided on the bottom surfaces of the piezoelectric material substrates 2 and 2A.
- the metal film plays a role of increasing the electromechanical coupling coefficient in the vicinity of the back surface of the piezoelectric material substrates 2 and 2A when a Lamb wave element is manufactured as an elastic wave device.
- the Lamb wave element has a structure in which comb electrodes are formed on the surfaces of the piezoelectric material substrates 2 and 2A, and the metal film of the piezoelectric material substrates 2 and 2A is exposed by the cavity provided in the support substrate 3. .
- Examples of the material of such a metal film include aluminum, an aluminum alloy, copper, and gold.
- a composite substrate including a piezoelectric material substrate that does not have a metal film on the bottom surface may be used.
- a metal film and an insulating film may be provided on the bottom surfaces of the piezoelectric material substrates 2 and 2A.
- the metal film serves as an electrode when a thin film resonator is manufactured as an acoustic wave device.
- the thin film resonator has a structure in which electrodes are formed on the front and back surfaces of the piezoelectric material substrates 2 and 2A, and the metal film of the piezoelectric material substrates 2 and 2A is exposed by using the insulating film as a cavity.
- the material for such a metal film include molybdenum, ruthenium, tungsten, chromium, and aluminum.
- the material for the insulating film include silicon dioxide, phosphorous silica glass, and boron phosphorous silica glass.
- the material constituting the electrode pattern on the piezoelectric material substrates 2 and 2A is preferably aluminum, aluminum alloy, copper, or gold, and more preferably aluminum or aluminum alloy.
- As the aluminum alloy it is preferable to use Al mixed with 0.3 to 5% by weight of Cu.
- Ti, Mg, Ni, Mo, Ta may be used instead of Cu.
- the piezoelectric material substrates 2 and 2A used in the present invention may be single crystals. If the material of the piezoelectric material substrates 2 and 2A is a single crystal, the surface of the piezoelectric material substrates 2 and 2A can be easily activated. However, when an intermediate layer is provided on the surfaces of the piezoelectric material substrates 2 and 2A, the bonding surface of the intermediate layer can be activated, so the piezoelectric material substrates 2 and 2A do not have to be single crystals, and the surfaces thereof are rough. It may be a surface.
- the piezoelectric material substrates 2 and 2A are made of lithium tantalate (LT) single crystal, lithium niobate (LN) single crystal, lithium niobate-lithium tantalate solid solution single crystal, crystal, lithium borate. Can be illustrated. Of these, LT or LN is more preferable. LT and LN are suitable as surface acoustic wave devices for high frequencies and wideband frequencies because of the high propagation speed of surface acoustic waves and a large electromechanical coupling coefficient.
- the normal direction of the principal surfaces 2a and 2b of the piezoelectric material substrates 2 and 2A is not particularly limited.
- the piezoelectric material substrates 2 and 2A are made of LT
- the X direction which is the propagation direction of the surface acoustic wave is used. It is preferable to use a direction rotated about 36 to 47 ° (for example, 42 °) from the Y axis to the Z axis around the axis because of a small propagation loss.
- the piezoelectric material substrates 2 and 2A are made of LN, those having a rotation direction of 60 to 68 ° (for example, 64 °) from the Y axis to the Z axis are used around the X axis as the propagation direction of the surface acoustic wave. Is preferable because of low propagation loss.
- the size of the piezoelectric material substrates 2 and 2A is not particularly limited. For example, the diameter is 50 to 150 mm and the thickness is 0.2 to 60 ⁇ m.
- the material of the support substrate 3 is preferably made of a material selected from the group consisting of silicon, sialon, mullite, sapphire, and translucent alumina. Thereby, the temperature characteristic of the frequency of the acoustic wave elements 5 and 5A can be further improved.
- the bonding layer 1A between the piezoelectric material substrates 2, 2A and the support substrate 3 is made of quartz. Quartz is a trigonal single crystal of SiO 2 .
- the thickness of the bonding layer 1A is preferably 0.05 ⁇ m or more, more preferably 0.1 ⁇ m or more, and more preferably 0.5 ⁇ m or more from the viewpoint of the insertion loss of the elastic wave and the temperature characteristics of the frequency. It is particularly preferred.
- the thickness of the bonding layer 1A is preferably 30 ⁇ m or less, preferably 25 ⁇ m or less, more preferably 20 ⁇ m or less, and particularly preferably 15 ⁇ m or less, from the viewpoints of elastic wave insertion loss and frequency temperature characteristics. It can also be 10 micrometers or less. As will be described later, by setting the thickness of the bonding layer 1A to 0.05 ⁇ m or more and 30 ⁇ m or less, an elastic wave element having a small propagation loss of elastic waves and good frequency temperature characteristics while maintaining the bonding strength. Can be produced.
- the material is one or more materials selected from the group consisting of tantalum pentoxide, niobium pentoxide, titanium oxide, and high resistance silicon. And By providing these intermediate layers, the bonding strength between the support substrate 3 and the piezoelectric material substrates 2 and 2A can be further improved.
- the thickness of the piezoelectric material substrate side intermediate layer 6 and the support substrate side intermediate layer 7 is preferably 0.01 ⁇ m or more, and more preferably 0.05 ⁇ m or more from the viewpoint of bonding strength. From the viewpoint of insertion loss and frequency temperature characteristics, 0.2 ⁇ m or less is preferable, and 0.1 ⁇ m or less is more preferable.
- Each method for forming the piezoelectric material substrate-side intermediate layer 6 and the support substrate-side intermediate layer 7 is not limited, and examples thereof include sputtering, chemical vapor deposition (CVD), and vapor deposition.
- the bonding surface 2a of the piezoelectric material substrate 2 When the bonding surface 2a of the piezoelectric material substrate 2, the bonding surface 1a of the crystal plate 1, and the bonding surface 3a of the support substrate 3 are used for direct bonding, it is preferable to flatten them and then activate them. Further, when the piezoelectric material substrate side intermediate layer 6 is provided on the bonding surface 2 a of the piezoelectric material substrate 2, and when the support substrate side intermediate layer 7 is provided on the bonding surface 3 a of the support substrate 3, these intermediate layers 6. , 7 are preferably flattened and activated. When the piezoelectric material substrate-side intermediate layer 6 is provided on the bonding surface 2a of the piezoelectric material substrate 2, the bonding surface 2a of the piezoelectric material substrate 2 may be roughened.
- This rough surface is a surface in which periodic irregularities are uniformly formed in the surface, the arithmetic average roughness is 0.05 ⁇ m ⁇ Ra ⁇ 0.5 ⁇ m, and the height Ry from the lowest valley bottom to the largest mountain top is 0.5 ⁇ m ⁇ The range is Ry ⁇ 5 ⁇ m.
- the suitable roughness depends on the wavelength of the elastic wave and is appropriately selected so that reflection of the bulk wave can be suppressed.
- the roughening method includes grinding, polishing, etching, sand blasting, and the like.
- the method of flattening each joint surface 1a, 2a, 3a, 6a, 7a includes lapping and chemical mechanical polishing (CMP).
- the flat surface is preferably Ra ⁇ 1 nm, more preferably 0.3 nm or less.
- each of the bonding surfaces 1a, 2a, 3a, 6a, 7a is irradiated with a neutral beam.
- a neutral beam it is preferable to generate and irradiate the neutralized beam using an apparatus as described in Patent Document 3. That is, a saddle field type fast atomic beam source is used as the beam source. Then, an inert gas is introduced into the chamber, and a high voltage is applied to the electrodes from a DC power source.
- the saddle field type electric field generated between the electrode (positive electrode) and the casing (negative electrode) moves the electrons e, thereby generating atomic and ion beams by the inert gas.
- the ion beam is neutralized by the grid, so that a beam of neutral atoms is emitted from the fast atom beam source.
- the atomic species constituting the beam is preferably an inert gas (argon, nitrogen, etc.).
- the voltage during activation by beam irradiation is preferably 0.5 to 2.0 kV, and the current is preferably 50 to 200 mA.
- the temperature at this time is room temperature, but specifically, it is preferably 40 ° C. or lower, more preferably 30 ° C. or lower.
- the temperature at the time of joining is particularly preferably 20 ° C. or higher and 25 ° C. or lower.
- the pressure at the time of joining is preferably 100 to 20000 N.
- the surface can be activated by a plasma irradiation method. Irradiate plasma (N2, NH3, O2, Ar, etc.) to the bonding surface in a low vacuum (up to 10 Pa) to activate the surface. After irradiation, it is taken out into the atmosphere and the joining surfaces are brought into contact with each other and joined. After bonding, heating is performed at 200 to 300 ° C to improve the bonding strength.
- a plasma irradiation method Irradiate plasma (N2, NH3, O2, Ar, etc.) to the bonding surface in a low vacuum (up to 10 Pa) to activate the surface. After irradiation, it is taken out into the atmosphere and the joining surfaces are brought into contact with each other and joined. After bonding, heating is performed at 200 to 300 ° C to improve the bonding strength.
- the acoustic wave element 15 was produced according to the method described with reference to FIG. Specifically, a lithium tantalate substrate (LT substrate) having an orientation flat portion (OF portion), a diameter of 4 inches, and a thickness of 250 ⁇ m was used as the piezoelectric material substrate 2. Further, a silicon substrate having an OF portion, a diameter of 4 inches, and a thickness of 230 ⁇ m was prepared as the support substrate 3. As the LT substrate, a 46 ° Y-cut X-propagation LT substrate in which the propagation direction of the surface acoustic wave (SAW) is X and the cutting angle is a rotating Y-cut plate is used.
- SAW surface acoustic wave
- the surface 2a of the piezoelectric material substrate 2 and the surface 3a of the support substrate 3 were mirror-polished so that the arithmetic average roughness Ra was 1 nm.
- Arithmetic mean roughness was evaluated by an atomic force microscope (AFM) with a square field of 10 ⁇ m length ⁇ 10 ⁇ m width.
- a silicon oxide film 9 was formed on the surface 2a of the piezoelectric material substrate 2 with a thickness of 3.0 ⁇ m by sputtering.
- the arithmetic average roughness Ra after the film formation was 2 nm.
- a silicon oxide film 8 was formed on the surface 3a of the support substrate 3 by a sputtering method with a thickness of 3.0 ⁇ m.
- the arithmetic average roughness Ra after the film formation was 2 nm.
- each silicon oxide film was subjected to chemical mechanical polishing (CMP), each film thickness was set to 2.5 ⁇ m, and Ra was set to 0.3 nm.
- CMP chemical mechanical polishing
- each silicon oxide film was cleaned and removed, and then introduced into a vacuum chamber.
- Each of the bonding surfaces 8a and 9a was activated by a plasma activation method and then bonded to each other (see FIG. 5B).
- Reference numeral 10 denotes a bonding layer.
- the chamber pressure was 10 Pa
- the plasma was irradiated with O 2 plasma for 60 s
- the bonding load was 1000 N, 100 s.
- the surface 2b of the piezoelectric material substrate 2 was ground and polished so that the thickness became 3 ⁇ m from the initial 250 ⁇ m (see FIG. 5C). During the grinding and polishing process, no peeling of the joint could be confirmed. Moreover, it was 0.6 J / m ⁇ 2 > when the joining strength was evaluated by the crack opening method. Then, an electrode 4 was formed on the processed surface 2c of the piezoelectric material substrate 2A after grinding and polishing, and an acoustic wave element 15 was obtained.
- an acoustic wave element chip was produced from the acoustic wave element 15, and propagation loss and frequency temperature characteristics were measured.
- the IDT electrode 4 that generates surface acoustic waves was formed through a photolithography process. After the electrode 4 was formed, it was cut into small pieces by dicing, and an element having a propagation direction of 5 mm and a vertical direction of 4 mm was obtained. Further, a reference substrate of the same size for measuring the linear expansion coefficient was prepared without forming the IDT electrode 4.
- a lithium tantalate substrate having an orientation flat portion (OF portion), a diameter of 4 inches, and a thickness of 250 ⁇ m was used as the piezoelectric material substrate 2.
- a quartz substrate having an OF portion, a diameter of 4 inches, and a thickness of 230 ⁇ m was prepared as the support substrate 3.
- a 46 ° Y-cut X-propagation LT substrate in which the propagation direction of the surface acoustic wave (SAW) is X and the cutting angle is a rotating Y-cut plate is used.
- the surface 2a of the piezoelectric material substrate 2 and the surface 3a of the support substrate 3 were mirror-polished so that the arithmetic average roughness Ra was 1 nm.
- the surface 2 a of the piezoelectric material substrate 2 and the surface 3 a of the support substrate 3 were directly bonded under the same conditions as in Comparative Example 1.
- the silicon oxide films 8 and 9 were not formed as the bonding layers.
- the surface 2b of the piezoelectric material substrate 2 was ground and polished so that the thickness became 3 ⁇ m from the initial 250 ⁇ m. During the grinding and polishing process, no peeling of the joint could be confirmed. Moreover, it was 0.6 J / m ⁇ 2 > when the joining strength was evaluated by the crack opening method. Then, an electrode 4 was formed on the processed surface 2c of the piezoelectric material substrate 2A after grinding and polishing, and an acoustic wave element 15 was obtained.
- Example 1 According to the method described with reference to FIGS. 1 and 2, an acoustic wave element 5 was produced. Specifically, a lithium tantalate substrate (LT substrate) having an orientation flat portion (OF portion), a diameter of 4 inches, and a thickness of 250 ⁇ m was used as the piezoelectric material substrate 2. A quartz plate 1 having a diameter of 4 inches and a thickness of 250 ⁇ m was prepared. Further, a silicon substrate having an OF portion, a diameter of 4 inches, and a thickness of 230 ⁇ m was prepared as the support substrate 3.
- LT substrate lithium tantalate substrate having an orientation flat portion (OF portion), a diameter of 4 inches, and a thickness of 250 ⁇ m was used as the piezoelectric material substrate 2.
- a quartz plate 1 having a diameter of 4 inches and a thickness of 250 ⁇ m was prepared. Further, a silicon substrate having an OF portion, a diameter of 4 inches, and a thickness of 230 ⁇ m was prepared as the support substrate 3.
- a 46 ° Y-cut X-propagation LT substrate in which the propagation direction of the surface acoustic wave (SAW) is X and the cutting angle is a rotating Y-cut plate is used.
- the surface 2a of the piezoelectric material substrate 2 and the surface 3a of the support substrate 3 were mirror-polished so that the arithmetic average roughness Ra was 1 nm.
- the bonding surface 2a of the piezoelectric material substrate 2 and the bonding surface 1a of the crystal plate 1 were subjected to chemical mechanical polishing so that Ra was 0.3 nm or less.
- the joint surfaces 2a and 1a were cleaned and removed, and then introduced into a vacuum chamber.
- Each of the bonding surfaces 2a and 1a was activated by a plasma activation method and then bonded to each other.
- the chamber pressure was 10 Pa
- the plasma was irradiated with O 2 plasma for 60 s
- the bonding load was 1000 N, 100 s.
- the crystal plate 1 was ground and polished to a thickness of 0.1 ⁇ m, and a bonding layer 1A was obtained (see FIG. 1 (c)).
- Ra was adjusted to 0.3 nm or less by subjecting the bonding surface 1c of the bonding layer 1A and the bonding surface 3a of the support substrate 3 to chemical mechanical polishing.
- the joint surfaces 1c and 3a were cleaned and cleaned, and then introduced into the vacuum chamber.
- the respective joined surfaces were activated by a plasma activation method and then joined to each other (see FIG. 2A).
- the surface 2b of the piezoelectric material substrate 2 was ground and polished so as to have a thickness of 250 ⁇ m to 3 ⁇ m (see FIG. 2B). During the grinding and polishing process, no peeling of the joint could be confirmed. Moreover, it was 0.6 J / m ⁇ 2 > when the joining strength was evaluated by the crack opening method.
- an acoustic wave element chip was produced from the acoustic wave element 5, and propagation loss and frequency temperature characteristics were measured.
- the temperature characteristic of the frequency was measured in the range of 25 to 80 ° C. with the element on which the IDT electrode 4 was formed, it was ⁇ 15 ppm / K. Further, the propagation loss was -1.9 dB.
- the measurement results are shown in Table 1. From this, it was found that the acoustic wave device 5 manufactured in Example 1 has little propagation loss of acoustic waves and good frequency temperature characteristics while maintaining the bonding strength.
- Example 2 The elastic wave element 5 of each example was produced in the same manner as in Example 1.
- the thickness of the bonding layer 1A made of quartz was variously changed as shown in Table 1. Specifically, in Example 2, the thickness of the bonding layer 1A is 0.5 ⁇ m, in Example 3, the thickness of the bonding layer 1A is 5.0 ⁇ m, and in Example 4, the thickness of the bonding layer 1A is 10 ⁇ m. In Example 5, the thickness of the bonding layer 1A was 20 ⁇ m.
- Table 1 shows the bonding strength of the joined body, the propagation loss of the obtained acoustic wave device 5 and the temperature characteristics of the frequency for each example. When the temperature characteristic of the frequency was measured in the range of 25 to 80 ° C.
- Example 5 With the element on which the IDT electrode 4 was formed, it was ⁇ 14 ppm / K in Example 2, ⁇ 15 ppm / K in Example 3, and ⁇ 16 ppm / K in Example 4. K, in Example 5, it was ⁇ 21 ppm / K.
- the propagation loss was -1.1 dB in Example 2, -1.1 dB in Example 3, -1.2 dB in Example 4, and -2.3 dB in Example 5. From this, in the acoustic wave device 5 manufactured in Examples 2 to 5, even when the joining layer 1A is thick, the propagation loss of the acoustic wave is small and the frequency temperature characteristic is good while maintaining the joining strength. I understood that.
- Example 6 In accordance with the method described with reference to FIGS. 3 and 4, an acoustic wave element 5A was produced. Specifically, the same piezoelectric material substrate 2, crystal plate 1, and support substrate 3 as those in Example 1 were prepared.
- the piezoelectric material substrate-side intermediate layer 6 made of tantalum pentoxide having a thickness of 0.05 ⁇ m was formed on the bonding surface 1a of the quartz plate 1 by sputtering.
- the bonding surface 2a of the piezoelectric material substrate 2 and the bonding surface 6a of the piezoelectric material substrate side intermediate layer 6 were cleaned and removed, and then introduced into the vacuum chamber. After evacuation to a level of 10 ⁇ 6 Pa, high-speed atomic beams (acceleration voltage 1 kV, Ar flow rate 27 sccm) were irradiated for 120 seconds to the bonding surfaces of the respective substrates.
- the bonding surface 2a of the piezoelectric material substrate 2 and the bonding surface 6a of the piezoelectric material substrate side intermediate layer 6 are brought into contact with each other, and then pressurized at 10,000 N for 2 minutes to bond the piezoelectric material substrate 2 and the crystal plate 1 together. (FIG. 3B).
- the quartz plate 1 was ground and polished so that the thickness was 5.0 ⁇ m, and a bonding layer 1A was obtained (see FIG. 3C).
- a support substrate side intermediate layer 7 made of tantalum pentoxide having a thickness of 0.05 ⁇ m was formed on the bonding surface 1c of the bonding layer 1A by sputtering.
- the bonding surface 3a of the support substrate 3 and the bonding surface 7a of the support substrate side intermediate layer 7 were washed and removed, and then introduced into the vacuum chamber.
- the high-speed atomic beam (acceleration voltage 1 kV, Ar flow rate 27 sccm) was irradiated to the bonding surfaces 3a and 7a of the respective substrates for 120 seconds.
- the bonding surface 3a of the supporting substrate 3 and the bonding surface 7a of the supporting substrate side intermediate layer 7 are brought into contact with each other, and then pressed at 10,000 N for 2 minutes to bond the supporting substrate 3 and the piezoelectric material substrate 2 (FIG. 4). (A)).
- the surface 2b of the piezoelectric material substrate 2 was ground and polished so that the thickness became 3 ⁇ m from the initial 250 ⁇ m (see FIG. 4B). During the grinding and polishing process, no peeling of the joint could be confirmed. Moreover, it was 1.5 J / m ⁇ 2 > when the joining strength was evaluated by the crack opening method.
- Example 5 when the temperature characteristic of the frequency was measured in the range of 25 to 80 ° C. with the element on which the IDT electrode 4 was formed, it was ⁇ 15 ppm / K. Further, the propagation loss was only -0.9 dB. Further, the bonding strength was 1.5 J / m 2 .
- Examples 7 and 8 In the same manner as in Example 6, an acoustic wave element 5A was produced, and the temperature characteristics of the bonding strength, propagation loss, and frequency were measured. The measurement results are shown in Table 2. However, the material of the support substrate 3 was changed to sialon in Example 7 and mullite in Example 8. When the temperature characteristic of the frequency was measured in the range of 25 to 80 ° C. with the element on which the IDT electrode 4 was formed, it was ⁇ 10 ppm / K in Example 7 and ⁇ 14 ppm / K in Example 8. The propagation loss was only -0.7 dB in Example 7 and only -0.7 dB in Example 8. The bonding strength was 1.5 J / m 2 as in Example 6. From this, it was found that the acoustic wave device 5 manufactured in Examples 6 to 8 improved the bonding strength, had a small acoustic wave propagation loss, and had good frequency temperature characteristics.
- the bonding strength is equivalent to that of the comparative example, and the temperature characteristics of insertion loss and frequency are improved as a whole.
- the thickness of the bonding layer 1A made of quartz was 0.1 ⁇ m to 20 ⁇ m. However, if the thickness of the bonding layer 1A is 0.05 ⁇ m to 30 ⁇ m, the bonding strength is reduced. An elastic wave device having a small propagation loss of elastic waves and good frequency temperature characteristics can be manufactured while keeping the same.
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Abstract
Description
圧電性材料基板上の電極、
支持基板、および
前記圧電性材料基板と前記支持基板とを接合する接合層を備えている弾性波素子であって、
前記接合層が水晶からなることを特徴とする、弾性波素子に係るものである。
圧電性材料基板と水晶板とを接合する工程、
前記水晶板を加工して接合層を形成する工程、
前記接合層と支持基板とを接合する工程、および
前記圧電性材料基板上に電極を形成する工程
を有することを特徴とする、弾性波素子の製造方法に係るものである。
たとえば、図1(a)に示すように、圧電性材料基板2と水晶板1とを準備する。圧電性材料基板2の主面2aを接合面とし、また水晶板1の主面1aを接合面とする。そして、図1(b)に示すように、圧電性材料基板2と水晶板1とを直接接合する。次いで、図1(c)に示すように、水晶板1の主面1bを加工することによって所定厚さとし、水晶からなる接合層1Aを得る。この接合層1Aの接合面1cに対して、別体の支持基板3の接合面3aを対向させる。3bは支持基板3の底面である。
弾性波素子5、5Aとしては、弾性表面波デバイスやラム波素子、薄膜共振子(FBAR)などが知られている。例えば、弾性表面波デバイスは、圧電性材料基板の表面に、弾性表面波を励振する入力側のIDT(Interdigital Transducer)電極(櫛形電極、すだれ状電極ともいう)と弾性表面波を受信する出力側のIDT電極とを設けたものである。入力側のIDT電極に高周波信号を印加すると、電極間に電界が発生し、弾性表面波が励振されて圧電性材料基板上を伝搬していく。そして、伝搬方向に設けられた出力側のIDT電極から、伝搬された弾性表面波を電気信号として取り出すことができる。
また、粗面化加工の方法は、研削、研磨、エッチング、サンドブラストなどがある。
中性化ビームによる表面活性化を行う際には、特許文献3に記載のような装置を使用して中性化ビームを発生させ、照射することが好ましい。すなわち、ビーム源として、サドルフィールド型の高速原子ビーム源を使用する。そして、チャンバーに不活性ガスを導入し、電極へ直流電源から高電圧を印加する。これにより、電極(正極)と筺体(負極)との間に生じるサドルフィールド型の電界により、電子eが運動して、不活性ガスによる原子とイオンのビームが生成される。グリッドに達したビームのうち、イオンビームはグリッドで中和されるので、中性原子のビームが高速原子ビーム源から出射される。ビームを構成する原子種は、不活性ガス(アルゴン、窒素等)が好ましい。
図5を参照しつつ説明する方法に従って、弾性波素子15を作製した。
具体的には、オリエンテーションフラット部(OF部)を有し、直径が4インチ,厚さが250μmのタンタル酸リチウム基板(LT基板)を圧電性材料基板2として使用した。また、支持基板3として、OF部を有し、直径が4インチ,厚さが230μmのシリコン基板を用意した。LT基板は、弾性表面波(SAW)の伝搬方向をXとし、切り出し角が回転Yカット板である46°YカットX伝搬LT基板を用いた。圧電性材料基板2の表面2aと支持基板3の表面3aは、算術平均粗さRaが1nmとなるように鏡面研磨しておいた。算術平均粗さは原子間力顕微鏡(AFM)で、縦10μm×横10μmの正方形の視野を評価した。
具体的には、弾性表面波を発生させるIDT電極4は、フォトリソグラフィー工程を経て形成した。電極4を形成後、ダイシングにより小片化し、伝搬方向5mm、その垂直方向4mmの素子を得た。また、IDT電極4を形成せず、線膨張係数を計測するための同サイズの参照用基板も用意した。
なお、本例の測定結果は表1に要約して示す。
本例では、LT基板と水晶基板とをプラズマ活性化法によって直接接合し、弾性波素子15を作製した。
具体的には、オリエンテーションフラット部(OF部)を有し、直径が4インチ,厚さが250μmのタンタル酸リチウム基板(LT基板)を圧電性材料基板2として使用した。また、支持基板3として、OF部を有し、直径が4インチ,厚さが230μmの水晶基板を用意した。LT基板は、弾性表面波(SAW)の伝搬方向をXとし、切り出し角が回転Yカット板である46°YカットX伝搬LT基板を用いた。圧電性材料基板2の表面2aと支持基板3の表面3aは、算術平均粗さRaが1nmとなるように鏡面研磨しておいた。
図1、図2を参照しつつ説明した方法に従って、弾性波素子5を作製した。
具体的には、オリエンテーションフラット部(OF部)を有し、直径が4インチ,厚さが250μmのタンタル酸リチウム基板(LT基板)を圧電性材料基板2として使用した。また、直径が4インチ、厚さが250μmの水晶板1を準備した。更に、支持基板3として、OF部を有し、直径が4インチ,厚さが230μmのシリコン基板を用意した。LT基板は、弾性表面波(SAW)の伝搬方向をXとし、切り出し角が回転Yカット板である46°YカットX伝搬LT基板を用いた。圧電性材料基板2の表面2aと支持基板3の表面3aは、算術平均粗さRaが1nmとなるように鏡面研磨しておいた。
実施例1と同様にして各例の弾性波素子5を作製した。ただし、水晶からなる接合層1Aの厚さは、表1に示すように種々変更した。具体的には、実施例2では、接合層1Aの厚さが0.5μm、実施例3では、接合層1Aの厚さが5.0μm、実施例4では、接合層1Aの厚さが10.0μm、実施例5では、接合層1Aの厚さが20μmとした。
各例について、接合体の接合強度、得られた弾性波素子5の伝搬損失および周波数の温度特性を表1に示す。IDT電極4を形成した素子で、25~80℃の範囲で周波数の温度特性を計測したところ、実施例2では-14ppm/K、実施例3では-15ppm/K、実施例4では-16ppm/K、実施例5では-21ppm/Kとなった。また、伝搬損失は、実施例2では-1.1dB、実施例3では-1.1dB、実施例4では-1.2dB、実施例5では-2.3dBとなった。このことより、実施例2~5で作製した弾性波素子5では、接合層1Aを厚くした場合でも、接合強度を保ったまま、弾性波の伝搬損失が少なく、かつ、周波数の温度特性が良いことが分かった。
図3、図4を参照しつつ説明した方法に従って、弾性波素子5Aを作製した。
具体的には、実施例1と同様の圧電性材料基板2、水晶板1、支持基板3を準備した。
実施例6と同様にして、弾性波素子5Aを作製し、接合強度、伝搬損失および周波数の温度特性を測定した。測定結果を表2に示す。
ただし、支持基板3の材質は、実施例7ではサイアロンに、実施例8ではムライトに変更した。IDT電極4を形成した素子で、25~80℃の範囲で周波数の温度特性を計測したところ、実施例7では-10ppm/K、実施例8では-14ppm/Kとなった。また、伝搬損失は、実施例7では-0.7dB、実施例8では-0.7dBしかなかった。また、接合強度は、実施例6と同様、1.5J/m2となった。このことより、実施例6~8で作製した弾性波素子5では、接合強度が向上する上に、弾性波の伝搬損失が少なく、かつ、周波数の温度特性が良いことが分かった。
Claims (10)
- 圧電性材料基板、
前記圧電性材料基板上の電極、
支持基板、および
前記圧電性材料基板と前記支持基板とを接合する接合層を備えている弾性波素子であって、
前記接合層が水晶からなることを特徴とする、弾性波素子。 - 前記接合層の厚さが0.05μm以上、30μm以下であることを特徴とする、請求項1記載の弾性波素子。
- 前記接合層と前記圧電性材料基板との間に、五酸化タンタル、五酸化ニオブ、酸化チタンおよび高抵抗シリコンからなる群より選ばれた一種以上の材質からなる圧電性材料基板側中間層を備えていることを特徴とする、請求項1または2記載の弾性波素子。
- 前記接合層と前記支持基板との間に、五酸化タンタル、五酸化ニオブ、酸化チタンおよび高抵抗シリコンからなる群より選ばれた一種以上の材質からなる支持基板側中間層を備えていることを特徴とする、請求項1~3のいずれか一つの請求項に記載の弾性波素子。
- 前記支持基板が、シリコン、サイアロン、ムライト、サファイアおよび透光性アルミナからなる群より選ばれた材質からなることを特徴とする、請求項1~4のいずれか一つの請求項に記載の弾性波素子。
- 圧電性材料基板と水晶板とを接合する工程、
前記水晶板を加工して接合層を形成する工程、
前記接合層と支持基板とを接合する工程、および
前記圧電性材料基板上に電極を形成する工程
を有することを特徴とする、弾性波素子の製造方法。 - 前記接合層の厚さを0.05μm以上、30μm以下とすることを特徴とする、請求項6記載の方法。
- 前記圧電性材料基板と前記水晶板との間に、五酸化タンタル、五酸化ニオブ、酸化チタンおよび高抵抗シリコンからなる群より選ばれた一種以上の材質からなる圧電性材料基板側中間層を設ける工程を有することを特徴とする、請求項6または7記載の方法。
- 前記接合層と前記支持基板との間に、五酸化タンタル、五酸化ニオブ、酸化チタンおよび高抵抗シリコンからなる群より選ばれた一種以上の材質からなる支持基板側中間層を設ける工程を有することを特徴とする、請求項6~8のいずれか一つの請求項に記載の方法。
- 前記支持基板が、シリコン、サイアロン、ムライト、サファイアおよび透光性アルミナからなる群より選ばれた材質からなることを特徴とする、請求項6~9のいずれか一つの請求項に記載の方法。
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