WO2022190465A1 - 接合体 - Google Patents
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- WO2022190465A1 WO2022190465A1 PCT/JP2021/042542 JP2021042542W WO2022190465A1 WO 2022190465 A1 WO2022190465 A1 WO 2022190465A1 JP 2021042542 W JP2021042542 W JP 2021042542W WO 2022190465 A1 WO2022190465 A1 WO 2022190465A1
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- Prior art keywords
- piezoelectric material
- substrate
- bonding
- material substrate
- support substrate
- Prior art date
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- 239000000758 substrate Substances 0.000 claims abstract description 132
- 239000000463 material Substances 0.000 claims abstract description 72
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 21
- 239000010703 silicon Substances 0.000 claims abstract description 21
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 13
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 13
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 20
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 9
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 9
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
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- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims description 3
- 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 3
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 3
- 229910052863 mullite Inorganic materials 0.000 claims description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 2
- 229910052744 lithium Inorganic materials 0.000 claims description 2
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- 238000005304 joining Methods 0.000 abstract description 3
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- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
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- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
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- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
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- 239000010931 gold Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
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- 230000001678 irradiating effect Effects 0.000 description 1
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- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
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- 238000005245 sintering Methods 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 229910001948 sodium oxide Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
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- 239000010937 tungsten Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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 elements; 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
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/25—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
Definitions
- the present invention relates to a bonded body of a piezoelectric material substrate and a support substrate made of silicon.
- Acoustic wave devices such as surface acoustic wave devices that can function as filter elements and oscillators used in mobile phones, Lamb wave elements using piezoelectric thin films, and thin film resonators (FBAR: Film Bulk Acoustic Resonator).
- FBAR Film Bulk Acoustic Resonator
- a device is known in which a support substrate and a piezoelectric material substrate for propagating surface acoustic waves are bonded together, and a comb-shaped electrode capable of exciting surface acoustic waves is provided on the surface of the piezoelectric material substrate. .
- the piezoelectric material substrate After bonding a piezoelectric material substrate to a support substrate made of silicon via a bonding layer made of metal oxide, the piezoelectric material substrate is subjected to a polishing process to be thinned to improve piezoelectric characteristics. is necessary for However, when the piezoelectric material substrate is thinned by processing, the processing load sometimes causes separation from the interface between the support substrate made of silicon and the bonding layer made of metal oxide. This is because the adhesion strength of the metal oxide to the silicon substrate surface is insufficient.
- An object of the present invention is to firmly bond a piezoelectric material substrate to a support substrate made of silicon via a bonding layer made of metal oxide, thereby suppressing separation from the support substrate during processing of the piezoelectric material substrate. That is.
- the present invention provides a support substrate made of silicon, A bonding layer provided on a bonding surface of a piezoelectric material substrate and the supporting substrate, the bonding layer comprising a metal oxide, wherein the bonding surface of the supporting substrate has an elemental aluminum content of 1.5.
- the present invention relates to a bonded body characterized by having 0 ⁇ 10 11 to 1.0 ⁇ 10 15 atoms/cm 2 .
- the present invention relates to an acoustic wave device, comprising: the bonded body; and an electrode provided on the piezoelectric material substrate.
- a piezoelectric material substrate is firmly bonded to a support substrate made of silicon via a bonding layer made of metal oxide, thereby suppressing separation from the support substrate during processing of the piezoelectric material substrate. be able to.
- FIG. (a) shows a state in which the bonding surface 4a of the piezoelectric material substrate 4 is activated by the plasma A
- (b) shows a state in which the bonding surface 1a of the supporting substrate 1 is processed B
- (c) 4 shows a state in which the bonding surface 2a of the bonding layer 2 on the support substrate 1 is activated by plasma C.
- FIG. (a) shows a state in which the piezoelectric material substrate 4 and the support substrate 1 are bonded
- (b) shows a state in which the piezoelectric material substrate 4A is thinned by processing
- (c) shows the piezoelectric material substrate 4A.
- a state in which an electrode 6 is provided thereon is shown.
- FIG. 10 is a diagram showing the state of the interface between the support substrate and the bonding layer when the piezoelectric material substrate is polished in a comparative example.
- FIG. 10 is a diagram showing the state of the interface between the support substrate and the bonding layer when the piezoelectric material substrate is polished in the example.
- FIG. 1 and 2 are schematic diagrams for explaining a manufacturing example in which a support substrate is directly bonded to a piezoelectric material substrate.
- the piezoelectric material substrate 4 has main surfaces 4a and 4b. Plasma is applied to the main surface 4a of the piezoelectric material substrate 4 as indicated by the arrow A to activate the main surface 4a to be an activated surface.
- the bonding surface 1a of the support substrate 1 is subjected to processing B to adjust the amount of aluminum element. 1b is the main surface opposite to the joint surface 1a.
- a bonding layer 2 is provided on the bonding surface 1a of the support substrate 1.
- the bonding surface 2a of the bonding layer 2 is activated by irradiating the plasma C to form an activated surface.
- the activated bonding surface 2a of the bonding layer 2 and the activated main surface 4a of the piezoelectric material substrate 4 are directly bonded to obtain the bonded body 5.
- the bonding surface 4b of the piezoelectric material substrate 4 of the bonded body 1 is further polished to reduce the thickness of the piezoelectric material substrate 4A as shown in FIG. 2(b), thereby obtaining a bonded body 5A.
- 4c is a polished surface.
- the elastic wave element 7 is produced by forming a predetermined electrode 6 on the polished surface 4c of the piezoelectric material substrate 4A.
- the support substrate is made of silicon.
- the relative density of the support substrate is preferably 95.5% or more, and may be 100%, from the viewpoint of bonding strength. Relative density is measured by the Archimedes method.
- the manufacturing method of the support substrate is not particularly limited, but a sintered body is preferable.
- the silicon that constitutes the support substrate is preferably high resistance silicon.
- High-resistivity silicon means silicon with a volume resistivity of 1000 ⁇ cm or more.
- the upper limit of the volume resistivity of high resistance silicon is usually 200 k ⁇ cm due to manufacturing limitations.
- the amount of aluminum element on the bonding surface of the support substrate is set to 1.0 ⁇ 10 11 to 1.0 ⁇ 10 15 atoms/cm 2 . That is, by allowing the aluminum element to exist on the bonding surface of the support substrate made of silicon, it is possible to suppress separation along the interface between the support substrate and the bonding layer made of metal oxide during processing for thinning the piezoelectric material substrate. From this point of view, the amount of aluminum element on the bonding surface of the support substrate is set to 1.0 ⁇ 10 11 atoms/cm 2 or more, and more preferably 1.0 ⁇ 10 12 atoms/cm 2 or more. In addition, it is difficult to increase the amount of aluminum element on the bonding surface of the supporting substrate to exceed 1.0 ⁇ 10 15 atoms/cm 2 due to manufacturing limitations.
- the amount of aluminum element in the bonding surface of the support substrate is measured by ICP-MS (inductively coupled plasma mass spectrometer). Specifically, the following measurement conditions are used. That is, the bonding surface of the support substrate was treated with hydrofluoric acid vapor, and then trace contaminant components on the bonding surface were recovered, and this recovered solution was used as a sample solution. The metal elements in the sample solution were analyzed with a Perkin Elmer ICP mass spectrometer.
- the bonding surface of the supporting substrate is polished with an abrasive made of alumina. Further, by blasting the bonding surface of the supporting substrate with abrasive grains made of alumina, the aluminum element can be left on the bonding surface.
- the aluminum element distributed on the bonding surface of the support substrate contributes to the bonding with the metal oxide that constitutes the bonding layer, improving the adhesion strength, thereby ensuring the adhesion strength that can withstand the processing load during the production of the piezoelectric thin film. It is considered possible.
- the grain size of the abrasive grains to be brought into contact with the bonding surface of the supporting substrate is preferably 1 um to 7 um. If the particle size of the abrasive grains is less than 1 ⁇ m, the particle size is too small to progress processing. In particular, when the grain size of the abrasive grains is set to 1.2 ⁇ m, Al can be densely contained in the entire bonding surface of the support substrate.
- the metal oxide forming the bonding layer is preferably selected from the group consisting of silicon oxide, sialon, cordierite, mullite and alumina, and silicon oxide is particularly preferred.
- Sialon is a ceramic obtained by sintering a mixture of silicon nitride and alumina, and has the following composition. Si 6-z Al z O z N 8-z That is, sialon has a composition in which alumina is mixed in silicon nitride, and z indicates the mixing ratio of alumina. z is more preferably 0.5 or more. Also, z is more preferably 4.0 or less.
- Alumina is polycrystalline with the composition Al 2 O 3 .
- Cordierite is a ceramic with the composition 2MgO.2Al2O3.5SiO2 .
- Mullite is a ceramic with a composition ranging from 3Al 2 O 3 .2SiO 2 to 2Al 2 O 3 .SiO 2 .
- the material of the piezoelectric material substrate is not limited as long as it has the required piezoelectricity, but a single crystal having a composition of LiAO 3 is preferred.
- A is one or more elements selected from the group consisting of niobium and tantalum.
- LiAO 3 may be lithium niobate, lithium tantalate, or a lithium niobate-lithium tantalate solid solution.
- Silicon oxide forming the bonding layer has a composition of Si (1 ⁇ x) O x (0.008 ⁇ x ⁇ 2/3).
- the silicon oxide has a composition of Si (1-x) O x (0.008 ⁇ x ⁇ 0.408).
- the thickness of the bonding layer is not particularly limited, it is preferably 0.01 to 10 ⁇ m, more preferably 0.01 to 0.5 ⁇ m, from the viewpoint of manufacturing cost.
- a method for forming the bonding layer is not limited, but can be exemplified by sputtering, chemical vapor deposition (CVD), and vapor deposition.
- the oxygen ratio (x) of the bonding layer can be controlled by adjusting the amount of oxygen gas flowed into the chamber during reactive sputtering using Si as the sputtering target.
- Specific manufacturing conditions for the bonding layer depend on the specifications of the chamber, and are appropriately selected.
- the pressure is 10 ⁇ 2 Pa, and the film formation temperature is room temperature.
- B-doped Si can be exemplified as the Si target.
- the activated bonding surface of the bonding layer and the activated bonding surface of the piezoelectric material substrate are directly bonded.
- the arithmetic average roughness Ra of the activated bonding surface of the bonding layer is preferably 1 nm or less, more preferably 0.3 nm or less.
- the arithmetic mean roughness Ra of the activated bonding surface of the piezoelectric material substrate is preferably 1 nm or less, more preferably 0.3 nm or less. This further improves the bonding strength between the piezoelectric material substrate and the bonding layer.
- the use of the joined body of the present invention is not particularly limited, and for example, it can be suitably applied to acoustic wave devices and optical devices.
- a surface acoustic wave device has, on the surface of a piezoelectric material substrate, an input-side IDT (Interdigital Transducer) electrode (comb-shaped electrode or interdigital electrode) that excites a surface acoustic wave and an output-side electrode that receives the surface acoustic wave. and an IDT electrode.
- IDT Interdigital Transducer
- a high-frequency signal is applied to the IDT electrodes on the input side, an electric field is generated between the electrodes, and surface acoustic waves are excited and propagated on the piezoelectric material substrate. Then, the propagated surface acoustic wave can be taken out as an electric signal from the IDT electrode on the output side provided in the propagation direction.
- the bottom surface of the piezoelectric material substrate may have a metal film.
- the metal film plays a role of increasing the electromechanical coupling coefficient in the vicinity of the back surface of the piezoelectric material substrate when a Lamb wave element is manufactured as an acoustic wave device.
- the Lamb wave element has a structure in which comb-teeth electrodes are formed on the surface of the piezoelectric material substrate, and the metal film of the piezoelectric material substrate is exposed by a cavity provided in the supporting substrate. Examples of materials for such metal films include aluminum, aluminum alloys, copper, and gold.
- a composite substrate having a piezoelectric material layer without a metal film on the bottom surface may be used.
- the bottom surface of the piezoelectric material substrate may have a metal film and an insulating film.
- 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 substrate, and the metal film of the piezoelectric material substrate is exposed by forming the insulating film as a cavity.
- Examples of materials for such metal films include molybdenum, ruthenium, tungsten, chromium, and aluminum.
- materials for the insulating film include silicon dioxide, phosphorus silica glass, boron phosphorus silica glass, and the like.
- examples of optical elements include an optical switching element, a wavelength conversion element, and an optical modulation element. Also, a periodically poled structure can be formed in the piezoelectric material substrate.
- the object of the present invention is an acoustic wave device
- the material of the piezoelectric material substrate is lithium tantalate, 36 to 47 from the Y axis to the Z axis centering on the X axis, which is the propagation direction of the surface acoustic wave. It is preferable to use the direction rotated by .degree. (for example, 42.degree.) because the propagation loss is small.
- the piezoelectric material substrate is made of lithium niobate
- the direction rotated from the Y-axis to the Z-axis by 60 to 68° (for example, 64°) around the X-axis, which is the propagation direction of the surface acoustic wave, is used. It is preferable to use it because the propagation loss is small.
- the size of the piezoelectric material substrate is not particularly limited, it is, for example, 50 to 150 mm in diameter and 0.2 to 60 ⁇ m in thickness.
- the following method is preferred for obtaining the conjugate of the present invention.
- plasma is applied to the bonding surface of the bonding layer and the bonding surface of the piezoelectric material substrate to activate each bonding surface.
- the atmosphere for surface activation is an atmosphere containing nitrogen or oxygen.
- the atmosphere may be oxygen only, nitrogen only, or a mixture of oxygen, nitrogen, hydrogen, and argon. In the case of a mixed gas, there is no particular limitation, but the ratio may be appropriately adjusted depending on the relationship with the bonding strength.
- the atmospheric pressure during surface activation is preferably 100 Pa or less, more preferably 80 Pa or less. Also, the atmospheric pressure is preferably 30 Pa or higher, more preferably 50 Pa or higher.
- the temperature during plasma irradiation is set to 150° C. or lower. As a result, it is possible to obtain the bonded body 7 having high bonding strength and free from deterioration of the piezoelectric material. From this point of view, the temperature during plasma irradiation is set to 150° C. or lower, and more preferably 100° C. or lower. Also, the energy during plasma irradiation is preferably 30 to 150W. Moreover, the product of the energy during plasma irradiation and the irradiation time is preferably 0.1 to 1.0 Wh.
- the bonding surface 4a of the piezoelectric material substrate and the bonding surface 2a of the bonding layer are flattened before the plasma treatment.
- Methods for flattening the bonding surfaces 2a, 4a include lap polishing, chemical mechanical polishing (CMP), and the like.
- the arithmetic mean roughness Ra of the flat surface is preferably 1 nm or less, more preferably 0.3 nm or less.
- the activated bonding surface of the piezoelectric material substrate and the activated bonding surface of the bonding layer are brought into contact and bonded.
- the joined body is heat-treated, so that the piezoelectric material substrate can be given strength to withstand the polishing process.
- Such heat treatment temperature is preferably 100 to 150.degree.
- the thickness can be reduced by processing the piezoelectric material substrate after this heat treatment.
- the bonding strength is improved by heat-treating (annealing) the bonded body.
- the temperature during the heat treatment is set to 250° C. or higher, and more preferably 270° C. or higher.
- the temperature during this heat treatment is set to 350° C. or lower in order to prevent damage to the joined body, and is more preferably 300° C. or lower.
- the activated surfaces are brought into contact with each other and joined.
- the temperature at this time is normal temperature, specifically, it is preferably 40° C. or less, more preferably 30° C. or less.
- the temperature at the time of joining is particularly preferably 20° C. or higher and 25° C. or lower.
- the pressure during bonding is preferably 100 to 20000N.
- a joined body of each example shown in Table 1 was produced.
- a lithium tantalate substrate (LT substrate) having an OF portion, a diameter of 4 inches, and a thickness of 250 ⁇ m was used as the piezoelectric material substrate 4 .
- LT substrate a 46° Y-cut X-propagation LT substrate was used in which the surface acoustic wave (SAW) propagation direction was X and the cut-out angle was a rotated Y-cut plate.
- the bonding surface 4a of the piezoelectric material substrate 4 was mirror-polished so that the arithmetic mean roughness Ra was 0.3 nm. However, Ra is measured in a field of view of 10 ⁇ m ⁇ 10 ⁇ m with an atomic force microscope (AFM).
- AFM atomic force microscope
- a support substrate 1 made of high resistance ( ⁇ 2 k ⁇ cm) silicon having an orientation flat (OF) portion, a diameter of 4 inches and a thickness of 230 ⁇ m was prepared.
- Surfaces 1a and 1b of support substrate 1 are finished by chemical mechanical polishing (CMP), and each has an arithmetic mean roughness Ra of 0.2 nm.
- CMP chemical mechanical polishing
- the bonding surface of the supporting substrate was blasted using fine powder abrasive white alumina having an average particle size of 2 ⁇ m.
- the composition of the abrasive is as follows.
- Aluminum oxide 96% by mass or more Sodium oxide, iron oxide, silicon dioxide each less than 1% by mass
- the arithmetic mean roughness Ra after polishing was 1 nm to 10 nm.
- the aluminum element content of the bonding surface of the support substrate of each example was analyzed by ICP-MS, and the results are shown in Table 1.
- a bonding layer 2 made of SiO 2 was formed to a thickness of 1 ⁇ m on the bonding surface of the supporting substrate, and the bonding surface 2a was polished by CMP to about 0.1 ⁇ m to be planarized.
- ultrasonic cleaning was performed using pure water, and the bonding surfaces of the piezoelectric material substrate and the bonding layer were dried by spin drying.
- the supporting substrate after cleaning was introduced into a plasma activation chamber, and the bonding surface was activated at 30° C. with nitrogen gas plasma.
- the piezoelectric material substrate was introduced into the plasma activation chamber, and the bonding surface of the bonding layer was surface-activated with nitrogen gas plasma at 30°C.
- the surface activation time was 40 seconds and the energy was 100W. For the purpose of removing particles attached during surface activation, the same ultrasonic cleaning and spin drying as above were performed again.
- the bonding surface of the piezoelectric material substrate and the bonding surface of the bonding layer were aligned, and the bonding surfaces activated at room temperature were brought into contact with each other.
- the bonding wave As a result of applying pressure to the center of the superimposed substrates, it was observed that the adhesion between the substrates spread (so-called bonding wave), and it was confirmed that the pre-bonding was performed satisfactorily.
- the joined body was placed in an oven in a nitrogen atmosphere and heated at 130° C. for 4 hours.
- the surface of the piezoelectric material substrate of the joined body was removed from the oven and thinned to 1 ⁇ m by grinding and polishing.
- the amount of aluminum element in each bonding surface of each supporting substrate was changed by controlling the strength (processing pressure) and processing time during processing.
- the processing pressure was adjusted within the range of 0.1 MPa to 0.5 MPa, and the processing time was adjusted within the range of 1 minute to 5 minutes. The higher the pressure and the longer the processing time, the greater the amount of aluminum element present on the bonding surface of the support substrate.
- FIG. 3 shows an optical photograph taken with a digital camera of the bonding interface when the amount of aluminum element is 7.0 ⁇ 10 9 atoms/cm 2 .
- a peeled portion was generated on the lower left side in FIG. 3, and the area ratio of the peeled portion was 30%.
- FIG. 4 shows an optical photograph taken with a digital camera of the bonding interface when the amount of aluminum element is 2.0 ⁇ 10 13 atoms/cm 2 . In this example, no delamination portion occurred at the bonding interface.
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Abstract
Description
圧電性材料基板、および
前記支持基板の接合面上に設けられた接合層であって、金属酸化物からなる接合層
を有しており、前記支持基板の前記接合面におけるアルミニウム元素量が1.0×1011~1.0×1015atoms/cm2であることを特徴とする、接合体に係るものである。
前記圧電性材料基板上に設けられた電極
を備えていることを特徴とする、弾性波素子に係るものである。
図1、図2は、支持基板を圧電性材料基板に直接接合する製造例を説明するための模式図である。
次いで、接合体1の圧電性材料基板4の接合面4bを更に研磨加工し、図2(b)に示すように圧電性材料基板4Aの厚さを小さくし、接合体5Aを得る。4cは研磨面である。
すなわち、フッ化水素酸蒸気にて支持基板の接合面を処理し、次いで接合面上の微量汚染成分の回収を行い、この回収溶液を試料溶液とした。試料溶液中の金属元素を、パーキンエルマー製ICP質量分析装置で分析した。
セラミックスであり、以下のような組成を有する。
Si6-zAlzOzN8-z
すなわち、サイアロンは、窒化珪素中にアルミナが混合された組成を有しており、zがアルミナの混合比率を示している。zは、0.5以上が更に好ましい。また、zは、4.0以下が更に好ましい。
一実施形態においては、この珪素酸化物は、Si(1-x)Ox(0.008≦x≦0.408)の組成を有する。Si(1-x)Ox(0.008≦x≦0.408)この組成は、SiO2(x=0.667に対応する)に比べて酸素比率がかなり低くされている組成である。このような組成の珪素酸化物Si(1-x)Oxからなる接合層によって支持基板に対して圧電性材料基板を接合すると、接合層における絶縁性を高くすることができる。
接合層の成膜方法は限定されないが、スパッタリング(sputtering)法、化学的気相成長法(CVD)、蒸着を例示できる。ここで、特に好ましくは、スパッタターゲットをSiとした反応性スパッタリングの際に、チャンバー内に流す酸素ガス量を調整することによって、接合層の酸素比率(x)をコントロールすることが可能である。
本発明の接合体の用途は特に限定されず、例えば、弾性波素子や光学素子に好適に適用できる。
まず接合層の接合面および圧電性材料基板の接合面にプラズマを照射することで、各接合面を活性化する。
表面活性化時の雰囲気は、窒素や酸素を含有する雰囲気とする。この雰囲気は、酸素のみであってよく、窒素のみであってよく、あるいは酸素と、窒素、水素、およびアルゴンとの混合ガスであってよい。混合ガスの場合には、特に限定されるものではないが、接合強度との関係によりその比率を適宜調整してもよい。
プラズマ照射時の温度は150℃以下とする。これによって、接合強度が高く、かつ圧電性材料の劣化のない接合体7が得られる。この観点から、プラズマ照射時の温度を150℃以下とするが、100℃以下とすることが更に好ましい。
また、プラズマ照射時のエネルギーは、30~150Wが好ましい。また、プラズマ照射時のエネルギーと照射時間との積は、0.1~1.0Whが好ましい。
具体的には、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4として使用した。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4の接合面4aは、算術平均粗さRaが0.3nmとなるように鏡面研磨しておいた。ただし、Raは、原子間力顕微鏡(AFM)によって10μm×10μmの視野で測定する。
酸化アルミニウム:96質量%以上
酸化ナトリウム、酸化鉄、二酸化ケイ素がそれぞれ1質量%未満
研磨加工後の算術平均荒さRaは1nm~10nmであった。また、各例の支持基板の接合面のアルミニウム元素含有量をICP-MSにて分析し、結果を表1に示す。
次いで、純水を用いた超音波洗浄を実施し、スピンドライにより圧電性材料基板および接合層の接合面を乾燥させた。次いで、洗浄後の支持基板をプラズマ活性化チャンバーに導入し、窒素ガスプラズマで30℃で接合面を活性化した。また、圧電性材料基板を同様にプラズマ活性化チャンバーに導入し、窒素ガスプラズマで30℃で接合層の接合面を表面活性化した。表面活性化時間は40秒とし、エネルギーは100Wとした。表面活性化中に付着したパーティクルを除去する目的で、上述と同じ超音波洗浄、スピンドライを再度実施した。
Claims (3)
- シリコンからなる支持基板、
圧電性材料基板、および
前記支持基板の接合面上に設けられた接合層であって、金属酸化物からなる接合層
を有しており、前記支持基板の前記接合面におけるアルミニウム元素量が1.0×1011~1.0×1015atoms/cm2であることを特徴とする、接合体。 - 前記金属酸化物が、珪素酸化物、サイアロン、コージェライト、ムライトおよびアルミナからなる群より選ばれることを特徴とする、請求項1記載の接合体。
- 前記圧電性材料基板の材質が、ニオブ酸リチウム、タンタル酸リチウムおよびニオブ酸リチウム-タンタル酸リチウム固溶体からなる群より選ばれることを特徴とする、請求項1または2記載の接合体。
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JP2022520070A JP7183481B1 (ja) | 2021-03-10 | 2021-11-19 | 接合体 |
EP21930311.2A EP4117180A4 (en) | 2021-03-10 | 2021-11-19 | JOINT STRUCTURE |
CN202180013623.0A CN117280609A (zh) | 2021-03-10 | 2021-11-19 | 接合体 |
KR1020227028961A KR102539925B1 (ko) | 2021-03-10 | 2021-11-19 | 접합체 |
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Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7213314B2 (en) | 2002-07-03 | 2007-05-08 | Triquint, Inc. | Method of forming a surface acoustic wave (SAW) filter device |
JP2010287718A (ja) * | 2009-06-11 | 2010-12-24 | Sumitomo Electric Ind Ltd | 貼り合わせ基板及び貼り合わせ基板の製造方法 |
WO2014038693A1 (ja) * | 2012-09-07 | 2014-03-13 | 京セラ株式会社 | デバイスの製造方法 |
WO2015125770A1 (ja) * | 2014-02-18 | 2015-08-27 | 日本碍子株式会社 | 半導体用複合基板のハンドル基板および半導体用複合基板 |
JP2016225537A (ja) | 2015-06-02 | 2016-12-28 | 信越化学工業株式会社 | 酸化物単結晶薄膜を備えた複合ウェーハの製造方法 |
JP2017135553A (ja) * | 2016-01-27 | 2017-08-03 | 住友金属鉱山株式会社 | 圧電体複合基板の製造方法 |
WO2019181087A1 (ja) * | 2018-03-20 | 2019-09-26 | 日本碍子株式会社 | 圧電性材料基板と支持基板との接合体 |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012043615A1 (ja) * | 2010-09-28 | 2012-04-05 | 株式会社村田製作所 | 圧電デバイスの製造方法 |
JP5615472B1 (ja) | 2013-03-27 | 2014-10-29 | 日本碍子株式会社 | 複合基板及び弾性波デバイス |
KR102183134B1 (ko) * | 2016-03-25 | 2020-11-25 | 엔지케이 인슐레이터 엘티디 | 접합체 및 탄성파 소자 |
KR102222096B1 (ko) * | 2017-09-15 | 2021-03-04 | 엔지케이 인슐레이터 엘티디 | 탄성파 소자 및 그 제조 방법 |
CN112088439B (zh) * | 2018-05-16 | 2022-04-22 | 日本碍子株式会社 | 压电性材料基板与支撑基板的接合体 |
CN112868178B (zh) * | 2018-10-17 | 2025-02-07 | 日本碍子株式会社 | 接合体及弹性波元件 |
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Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7213314B2 (en) | 2002-07-03 | 2007-05-08 | Triquint, Inc. | Method of forming a surface acoustic wave (SAW) filter device |
JP2010287718A (ja) * | 2009-06-11 | 2010-12-24 | Sumitomo Electric Ind Ltd | 貼り合わせ基板及び貼り合わせ基板の製造方法 |
WO2014038693A1 (ja) * | 2012-09-07 | 2014-03-13 | 京セラ株式会社 | デバイスの製造方法 |
WO2015125770A1 (ja) * | 2014-02-18 | 2015-08-27 | 日本碍子株式会社 | 半導体用複合基板のハンドル基板および半導体用複合基板 |
JP2016225537A (ja) | 2015-06-02 | 2016-12-28 | 信越化学工業株式会社 | 酸化物単結晶薄膜を備えた複合ウェーハの製造方法 |
JP2017135553A (ja) * | 2016-01-27 | 2017-08-03 | 住友金属鉱山株式会社 | 圧電体複合基板の製造方法 |
WO2019181087A1 (ja) * | 2018-03-20 | 2019-09-26 | 日本碍子株式会社 | 圧電性材料基板と支持基板との接合体 |
Non-Patent Citations (1)
Title |
---|
See also references of EP4117180A4 |
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