WO2020189115A1 - Substrat composite, dispositif électronique, procédé de fabrication de substrat composite et procédé de fabrication de dispositif électronique - Google Patents

Substrat composite, dispositif électronique, procédé de fabrication de substrat composite et procédé de fabrication de dispositif électronique Download PDF

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WO2020189115A1
WO2020189115A1 PCT/JP2020/005744 JP2020005744W WO2020189115A1 WO 2020189115 A1 WO2020189115 A1 WO 2020189115A1 JP 2020005744 W JP2020005744 W JP 2020005744W WO 2020189115 A1 WO2020189115 A1 WO 2020189115A1
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substrate
composite
support substrate
piezoelectric
piezoelectric substrate
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PCT/JP2020/005744
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English (en)
Japanese (ja)
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小林　正宏
清行 奥長
益田　紀彰
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日本電気硝子株式会社
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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
    • H03H9/02—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
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02551—Characteristics of substrate, e.g. cutting angles of quartz substrates
    • 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
    • H10N30/01—Manufacture or treatment
    • H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
    • H10N30/085—Shaping or machining of piezoelectric or electrostrictive bodies by machining
    • H10N30/086—Shaping or machining of piezoelectric or electrostrictive bodies by machining by polishing or grinding
    • 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
    • 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
    • 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
    • H10N30/88—Mounts; Supports; Enclosures; Casings

Definitions

  • the present invention relates to a composite substrate, an electronic device using the composite substrate, and a composite substrate and a method for manufacturing the electronic device.
  • SAW filters Surface acoustic wave elements
  • the piezoelectric substrate for forming a surface acoustic wave element is required to have a high electromechanical coupling coefficient at a high sound velocity, lithium niobate (LiNbO 3 : hereinafter LN) capable of satisfying these required characteristics and the like.
  • Lithium tantalate (LiTaO 3 : hereinafter LT) is mainly used.
  • LN and LT have a large coefficient of thermal expansion, and the amount of thermal expansion and contraction due to a temperature change is large.
  • the thermal expansion / contraction behavior due to this temperature change affects the pass frequency band or cutoff frequency band of the bandpass filter.
  • the center frequency of the bandpass filter fluctuates, for example, the signal of the frequency that should originally pass through the bandpass filter is attenuated, and the filter characteristic, that is, the separation characteristic of a specific frequency signal deteriorates. Therefore, it is necessary to suppress the thermal expansion / contraction behavior of the surface acoustic wave element due to temperature changes.
  • Patent Document 1 proposes a composite substrate using a Sialon sintered body having a relatively small coefficient of thermal expansion as a support substrate.
  • An object of the present invention is a composite substrate, an electronic device using the composite substrate, a method for manufacturing the composite substrate, and the electronic device, which can enhance the stability of filter characteristics against temperature changes when used in an electronic device. Is to provide a manufacturing method for.
  • the composite substrate of the present invention is a composite substrate used for an electronic device, and includes a support substrate and a piezoelectric substrate provided on the support substrate, and the support substrate is a ⁇ -quartz solid solution and / or ⁇ -U. It is characterized in that it is composed of crystallized glass formed by precipitating a cryptotite solid solution.
  • the average coefficient of thermal expansion of the support substrate in the range of 30 ° C. or higher and 380 ° C. or lower is -1 ⁇ 10 -7 / ° C. or higher and 1 ⁇ 10 -7 / ° C. or lower.
  • Support substrate is in mass%, SiO 2 55% to 75%, Al 2 O 3 15% to 30%, Li 2 O 2% to 5%, Na 2 O 0% to 3%, K 2 O 0% to 3%, MgO 0% ⁇ 5 %, ZnO 0% ⁇ 3%, BaO 0% ⁇ 5%, TiO 2 0% ⁇ 5%, ZrO 2 0% ⁇ 4%, P 2 O 5 0% ⁇ 5%, It is preferably composed of crystallized glass having a composition containing 20 % to 2.5% of SnO.
  • the amount of ⁇ -quartz solid solution and / or ⁇ -eucryptite solid solution precipitated on the support substrate is preferably 50% by mass or more.
  • a bonding layer is further provided between the support substrate and the piezoelectric substrate, and the bonding layer may contain metal and its thickness may be 15 nm or less. Further, the support substrate and the piezoelectric substrate may be directly bonded.
  • the piezoelectric substrate is a lithium niobate crystal substrate or a lithium tantalate crystal substrate, and the thickness of the piezoelectric substrate is 20 ⁇ m or less.
  • the arithmetic average roughness Ra of the surface of the support substrate bonded to the piezoelectric substrate and the surface bonded to the piezoelectric substrate of the piezoelectric substrate is 0.5 nm or less, respectively.
  • the electronic device of the present invention includes the composite substrate and a comb-shaped electrode provided on the piezoelectric substrate, and is characterized in that it is configured to be capable of generating surface acoustic waves on the piezoelectric substrate.
  • the method for manufacturing a composite substrate of the present invention is the above-mentioned method for manufacturing a composite substrate, which includes a step of preparing a support substrate and a step of joining a piezoelectric substrate to the support substrate, and comprises a ⁇ -quartz solid solution and / or ⁇ -. It is characterized in that crystallized glass formed by precipitating a eucryptite solid solution is used as a support substrate.
  • the support substrate and the piezoelectric substrate In the process of joining the piezoelectric substrate to the support substrate, it is preferable to join the support substrate and the piezoelectric substrate by atomic diffusion bonding. Further, in the step of joining the piezoelectric substrate to the support substrate, it is preferable to join the support substrate and the piezoelectric substrate by surface activation bonding.
  • a step of polishing only the piezoelectric substrate side to make the composite substrate thinner is further provided.
  • the method for manufacturing an electronic device of the present invention is characterized by including a step of providing a comb-shaped electrode on the piezoelectric substrate of the composite substrate.
  • a composite substrate, an electronic device using the composite substrate, a method for manufacturing the composite substrate, and the electronic device which can enhance the stability of filter characteristics against temperature changes when used in an electronic device. Manufacturing method can be provided.
  • FIG. 1 is a front sectional view of the composite substrate according to the first embodiment of the present invention.
  • FIG. 2 is a front sectional view of a composite substrate according to a modified example of the first embodiment of the present invention.
  • FIG. 3 is a schematic perspective view of the electronic device according to the second embodiment of the present invention.
  • FIG. 1 is a front sectional view of the composite substrate according to the first embodiment of the present invention.
  • the composite substrate 1 of the present embodiment shown in FIG. 1 is used for an electronic device such as a surface acoustic wave element.
  • the composite substrate 1 includes a support substrate 2 and a piezoelectric substrate 3 provided on the support substrate 2.
  • the support substrate 2 has a first main surface 2a and a second main surface 2b facing each other.
  • the piezoelectric substrate 3 has a third main surface 3a and a fourth main surface 3b that face each other.
  • the first main surface 2a of the support substrate 2 is a surface bonded to the piezoelectric substrate 3.
  • the third main surface 3a of the piezoelectric substrate 3 is a surface bonded to the support substrate 2.
  • the first main surface 2a of the support substrate 2 and the third main surface 3a of the piezoelectric substrate 3 are directly joined.
  • the direct coupling refers to a bonding made of resin or the like without an adhesive layer.
  • a bonding layer such as a metal layer is formed between the bonding surfaces at the time of bonding is also included in the direct bonding.
  • the direct bonding includes the case where the bonding surfaces are directly bonded to each other without going through the bonding layer.
  • the composite substrate 1 of the present embodiment does not have a bonding layer between the support substrate 2 and the piezoelectric substrate 3.
  • the first main surface 2a of the support substrate 2 and the third main surface 3a of the piezoelectric substrate 3 are directly joined.
  • the piezoelectric substrate 3 is not particularly limited, but is, for example, a lithium niobate crystal substrate or a lithium tantalate crystal substrate.
  • the support substrate 2 is composed of crystallized glass obtained by precipitating a ⁇ -quartz solid solution and / or a ⁇ -eucryptite solid solution.
  • the average coefficient of thermal expansion of the support substrate 2 of the present embodiment at 30 ° C. or higher and 380 ° C. or lower is -1 ⁇ 10 -7 / ° C. or higher and 1 ⁇ 10 -7 / ° C. or lower.
  • the coefficient of thermal expansion of the support substrate 2 itself is -1 ⁇ 10 -7 / ° C. or higher and 1 ⁇ 10 -7 / ° C. or lower at 30 ° C. or higher and 380 ° C. or lower. As described above, the coefficient of thermal expansion of the support substrate 2 is substantially 0.
  • the amount of ⁇ -quartz solid solution and / or ⁇ -eucryptite solid solution precipitated on the support substrate 2 is preferably 50% by mass or more, more preferably 70% by mass or more. If the amount of ⁇ -quartz solid solution and / or ⁇ -eucryptite solid solution deposited is too small, it is difficult to obtain the effect of reducing the coefficient of thermal expansion. On the other hand, the upper limit of the precipitation amount of the ⁇ -quartz solid solution and / or the ⁇ -eucryptite solid solution is not particularly limited, but is practically 99% by mass or less. When both ⁇ -quartz solid solution and ⁇ -eucryptite are contained, it is preferable that the total amount satisfies the above range.
  • the support substrate 2 is not particularly limited as long as it can precipitate a ⁇ -quartz solid solution and / or a ⁇ -eucryptite solid solution.
  • the support substrate 2 has a mass% of SiO 2 55% to 75%, Al 2 O 3 15% to 30%, Li 2 O 2% to 5%, Na 2 O 0% to 3%, and K 2 O. 0% ⁇ 3%, MgO 0 % ⁇ 5%, ZnO 0% ⁇ 3%, BaO 0% ⁇ 5%, TiO 2 0% ⁇ 5%, ZrO 2 0% ⁇ 4%, P 2 O 5 0% ⁇ It is preferably composed of crystallized glass having a composition containing 5% and 20 % to 2.5% of SnO. The reason why the above glass composition range is preferable will be described below.
  • SiO 2 forms a glass skeleton and also serves as a constituent component of the main crystal.
  • the content of SiO 2 is preferably 55% to 75%, more preferably 60% to 75%. If the content of SiO 2 is too small, the coefficient of thermal expansion tends to be high and the chemical durability tends to be low. On the other hand, if the content of SiO 2 is too large, the meltability tends to decrease. Further, the viscosity of the glass melt increases, which tends to make it difficult to clarify or mold.
  • Al 2 O 3 forms a glass skeleton and also serves as a constituent of the main crystal.
  • the content of Al 2 O 3 is preferably 15% to 30%, more preferably 17% to 27%. If the content of Al 2 O 3 is too small, the coefficient of thermal expansion tends to be high and the chemical durability tends to be lowered. On the other hand, if the content of Al 2 O 3 is too large, the meltability tends to decrease. In addition, the viscosity tends to increase, making it difficult to clarify or molding. In addition, it becomes easy to devitrify.
  • Li 2 O is a constituent component of the main crystal, which has a great influence on crystallinity and is a component that improves meltability and moldability by lowering the viscosity.
  • the content of Li 2 O is preferably 2% to 5%, more preferably 2% to 4.8%. If the content of Li 2 O is too small, the main crystals are difficult to precipitate and the meltability is lowered. Further, the viscosity tends to increase, making it difficult to clarify or molding. On the other hand, if the content of Li 2 O is too large, devitrification is likely to occur.
  • Na 2 O is a component for lowering the viscosity and improving the meltability and moldability.
  • the content of Na 2 O is preferably 0% to 3%, more preferably 0.1% to 1%. If the content of Na 2 O is too large, devitrification tends to occur and the coefficient of thermal expansion tends to increase.
  • K 2 O is a component for lowering the viscosity and improving the meltability and moldability.
  • the K 2 O content is preferably 0% to 3%, more preferably from 0.1% to 1%. If the content of K 2 O is too large, devitrification tends to occur and the coefficient of thermal expansion tends to increase.
  • MgO is a component for adjusting the coefficient of thermal expansion.
  • the content of MgO is preferably 0% to 5%, more preferably 0.1% to 3%, and even more preferably 0.3% to 2%. If the content of MgO is too large, devitrification tends to occur and the coefficient of thermal expansion tends to increase.
  • ZnO is a component for adjusting the coefficient of thermal expansion.
  • the ZnO content is preferably 0% to 3%, more preferably 0.1% to 1%. If the ZnO content is too high, devitrification is likely to occur.
  • BaO is a component for improving meltability and moldability by lowering the viscosity.
  • the content of BaO is preferably 0% to 5%, more preferably 0.1% to 3%. If the BaO content is too high, devitrification is likely to occur.
  • TiO 2 and ZrO 2 are components that act as nucleating agents for precipitating crystals in the crystallization step.
  • the content of TiO 2 is preferably 0% to 5%, more preferably 1% to 4%.
  • the content of ZrO 2 is preferably 0% to 4%, more preferably 0.1% to 3%. If the content of TiO 2 or ZrO 2 is too high, devitrification is likely to occur.
  • P 2 O 5 is a component that promotes phase separation and assists in the formation of crystal nuclei.
  • the content of P 2 O 5 is preferably 0% to 5%, more preferably 0.1% to 4%. If the content of P 2 O 5 is too large, it becomes easy to separate the phases in the melting step, and it becomes difficult to obtain a glass having a desired composition.
  • SnO 2 is a component that acts as a fining agent.
  • the content of SnO 2 is preferably 0% to 2.5%, more preferably 0.1% to 2%. If the content of SnO 2 is too large, the color tone becomes too dark and the light is easily devitrified.
  • B 2 O 3 , SrO, CaO and the like can be appropriately contained as long as the effects of the present invention are not impaired.
  • the piezoelectric substrate 3 is not particularly limited, but is, for example, a lithium niobate crystal substrate or a lithium tantalate crystal substrate.
  • the feature of this embodiment is that the support substrate 2 in the composite substrate 1 is composed of crystallized glass obtained by precipitating a ⁇ -quartz solid solution and / or a ⁇ -eucryptite solid solution.
  • the coefficient of thermal expansion of the support substrate 2 can be made substantially zero. Therefore, the support substrate 2 hardly undergoes thermal expansion or contraction due to a temperature change.
  • the piezoelectric substrate 3 bonded to the support substrate 2 is restrained by the support substrate 2, thermal expansion / contraction of the piezoelectric substrate 3 is suppressed.
  • the composite substrate 1 is unlikely to thermally expand or contract due to temperature changes. Therefore, by using the composite substrate 1 of the present embodiment for an electronic device that utilizes a surface acoustic wave or the like, the stability of the filter characteristics with respect to a temperature change can be improved.
  • the average coefficient of thermal expansion of the support substrate 2 is preferably -1 ⁇ 10 -7 / ° C. or higher and 1 ⁇ 10 -7 / ° C. or lower at 30 ° C. or higher and 380 ° C. or lower as in the present embodiment.
  • the coefficient of thermal expansion of the support substrate 2 is within the above range, the stability of the filter characteristics of the electronic device with respect to temperature changes can be more reliably enhanced.
  • the support substrate 2 and the piezoelectric substrate 3 are directly bonded. Thereby, the binding force of the piezoelectric substrate 3 by the support substrate 2 can be effectively increased. Therefore, the stability of the filter characteristics of the electronic device with respect to the temperature change can be further enhanced.
  • the dimensions of the composite substrate 1 in a plan view are preferably ⁇ 50 mm or more and ⁇ 400 mm or less, more preferably ⁇ 100 mm or more and ⁇ 400 mm or less, and further preferably ⁇ 100 mm or more and ⁇ 300 mm or less.
  • the composite substrate 1 of the present embodiment is particularly suitable when used in a small electronic device because it can enhance the stability of the filter characteristics against a temperature change.
  • the composite substrate 1 is suitable as the substrate used for such an electronic device.
  • the thickness of the piezoelectric substrate 3 is preferably 20 ⁇ m or less, more preferably 5 ⁇ m or less, and even more preferably 2 ⁇ m or less. As a result, good device characteristics can be exhibited in the electronic device using the composite substrate 1.
  • the thickness of the piezoelectric substrate 3 is preferably 0.3 ⁇ m or more, and more preferably 1 ⁇ m or more. In this case, the piezoelectric substrate 3 is not easily damaged.
  • FIG. 2 is a front sectional view of the composite substrate according to the modified example of the first embodiment.
  • the composite substrate 11 includes a bonding layer 14 provided between the support substrate 2 and the piezoelectric substrate 3.
  • the bonding layer 14 is not particularly limited, but is, for example, a layer containing a metal such as a Ti layer or a layer containing a semiconductor such as a Si layer.
  • the bonding layer 14 may be a layer in which the components of the metal and the support substrate 2 and / or the piezoelectric substrate 3 are mixed. Further, the bonding layer 14 may be composed of a single metal or an alloy.
  • the thickness of the bonding layer 14 is preferably 15 nm or less, more preferably 10 nm or less, and further preferably 8 nm or less. In this case, the bonding layer 14 is unlikely to affect the amount of residual strain between the support substrate 2 and the piezoelectric substrate 3. Therefore, as in the first embodiment, the stability of the filter characteristics with respect to temperature changes can be enhanced.
  • the thickness of the bonding layer 14 is preferably 1 nm or more, more preferably 2 nm or more.
  • FIG. 3 is a schematic perspective view of the electronic device according to the second embodiment of the present invention.
  • the electronic device 20 includes the composite substrate 1 of the first embodiment, and the first comb-shaped electrode 25A and the second comb-shaped electrode 25B provided on the composite substrate 1.
  • An input terminal 26A is connected to the first comb-shaped electrode 25A.
  • An output terminal 26B is connected to the second comb-shaped electrode 25B.
  • the electronic device 20 is an elastic wave device.
  • the electronic device 20 is configured to be capable of generating elastic waves, specifically, elastic surface waves, on the piezoelectric substrate 3.
  • the elastic wave is excited by applying the signal input from the input terminal 26A to the first comb-shaped electrode 25A.
  • the elastic wave propagates through the piezoelectric substrate 3, is converted into a signal by the second comb-shaped electrode 25B, and the signal is taken out from the output terminal 26B.
  • the signal input from the input terminal 26A is filtered.
  • the circuit configuration of the electronic device 20 is not limited to the above.
  • the electronic device 20 may have at least one comb-shaped electrode.
  • the electronic device 20 has the composite substrate 1 of the first embodiment, it is possible to improve the stability of the filter characteristics against temperature changes.
  • the support substrate 2 shown in FIG. 1 is produced by melting a raw material batch prepared by blending a glass raw material at a predetermined ratio, molding the raw material into a predetermined shape, and crystallizing the glass raw material under a predetermined temperature condition.
  • the melting temperature of the glass batch is preferably about 1600 ° C to 1800 ° C from the viewpoint of productivity and homogeneity.
  • the crystallization conditions include heat treatment at 600 ° C. to 800 ° C. for 1 hour to 5 hours to generate crystal nuclei (crystal nucleation stage), and then at 800 ° C. to 950 ° C. for 0.5 hours to 3 hours. It is preferable to perform heat treatment to precipitate the main crystal (crystal growth stage).
  • each of the above surfaces is preferably an arithmetic average roughness Ra (hereinafter Ra): 0.5 nm or less, more preferably 0.3 nm or less, and 0.2 nm or less by polishing or the like. Is even more preferable.
  • Ra in this specification is based on JIS B 0601: 2013.
  • the total surface of each surface is preferably set to 1.5 ⁇ m or less, and more preferably 1.0 ⁇ m or less by polishing or the like.
  • the support substrate 2 and the piezoelectric substrate 3 can be suitably bonded by direct bonding, and the bonding strength can be increased more reliably.
  • the lower limit of Ra on each of the above surfaces is, for example, 0.05 nm or more.
  • the lower limit of TTV on each of the above surfaces is, for example, 0.5 ⁇ m or more.
  • the support substrate 2 and the piezoelectric substrate 3 can be suitably joined without causing an excessive increase in polishing time or the like in the flattening and smoothing steps.
  • the method for manufacturing the composite substrate 1 does not necessarily have to include a step of flattening and smoothing the first main surface 2a of the support substrate 2 and the third main surface 3a of the piezoelectric substrate 3.
  • the first main surface 2a of the support substrate 2 and the third main surface 3a of the piezoelectric substrate 3 are activated.
  • This activation is performed, for example, by irradiating the surface with a neutral atom beam of an inert gas (argon or the like), or by irradiating a plasma or an ion beam.
  • a neutral atom beam of an inert gas argon or the like
  • a plasma or an ion beam can be performed using, for example, an ion gun, a FAB (Fast Atom Beam) gun, or the like.
  • the FAB gun has a higher energy per particle than the ion gun, and has a high ability to remove the oxide film and the adsorption layer on the substrate surface that hinder the normal temperature bonding.
  • the piezoelectric substrate 3 and the support substrate 2 can be suitably bonded by direct bonding at room temperature in a later step, and the bonding strength can be increased more reliably.
  • the method for manufacturing the composite substrate 1 does not necessarily have to include a step of activating the respective surfaces of the piezoelectric substrate 3 and the support substrate 2.
  • the normal temperature refers to, for example, a temperature range of 5 to 50 ° C.
  • the first main surface 2a of the support substrate 2 and the third main surface 3a of the piezoelectric substrate 3 are joined by direct bonding. Specifically, both substrates are pressed with the first main surface 2a of the support substrate 2 and the third main surface 3a of the piezoelectric substrate 3 facing each other.
  • ADB atomic diffusion bonding
  • SAB surface-activated bonding, which can be bonded at room temperature, is preferable.
  • optical contacts may be used.
  • the ratio of the actually bonded area to the bonding interface between the support substrate 2 and the piezoelectric substrate 3 is preferably 80% or more, and more preferably 90% or more.
  • the bonding area ratio is large as described above, a good composite substrate in which the support substrate 2 and the piezoelectric substrate 3 are firmly bonded is obtained.
  • the thickness of the piezoelectric substrate 3 is preferably 20 ⁇ m or less, more preferably 5 ⁇ m or less, and even more preferably 2 ⁇ m or less by grinding and polishing. As a result, good device characteristics can be exhibited in the electronic device using the composite substrate 1.
  • the joining strength can be increased more reliably, so that the piezoelectric substrate 3 is unlikely to be peeled off from the support substrate 2 even by vibration during grinding and polishing.
  • the bonding layer 14 shown in FIG. 2 may be formed between the support substrate 2 and the piezoelectric substrate 3. For example, when ADB or SAB is used for bonding, the bonding layer 14 is formed between the support substrate 2 and the piezoelectric substrate 3.
  • the bonding layer 14 is bonded after the above-mentioned flattening and smoothing steps and before the above-mentioned activation step or room temperature bonding step.
  • a metal thin film is formed on the surface. Specifically, a step of forming a metal thin film made of, for example, Ti or the like is provided on at least one of the support substrate 2 and the piezoelectric substrate 3.
  • the metal thin film layer may be formed on the joint surface of both the support substrate 2 and the piezoelectric substrate 3, or may be formed on one of the joint surfaces of the support substrate 2 or the piezoelectric substrate 3.
  • Example 2 Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.
  • An example in which ADB is used as the joining method of the support substrate and the piezoelectric substrate is shown in Example 1.
  • An example in which SAB is used as the joining method is shown in Example 2.
  • Example 1 In Preparation mass% of the supporting substrate, SiO 2 66%, Al 2 O 3 23%, Li 2 O 4%, Na 2 O 0.5%, MgO 1%, BaO 1.5%, TiO 2 2 %, so that the glass having a composition of ZrO 2 2%, the raw material powder were blended, and homogeneously mixed.
  • the obtained raw material batch was melted at 1600 ° C. or higher and 1800 ° C. or lower until it became homogeneous to obtain molten glass.
  • the molten glass was formed into a plate shape.
  • the molten glass formed into a plate shape was cooled to room temperature using a slow cooling furnace to obtain a plate-shaped crystalline glass.
  • the plate-like crystalline glass was heated at a rate of 300 ° C./hour from room temperature to a temperature within the range of 760 ° C. or higher and 780 ° C. or lower, and held for 3 hours for nucleation.
  • the temperature was raised to a temperature within the range of 870 ° C. or higher and 890 ° C. or lower at a rate of 120 ° C./hour, and the temperature was maintained for 1 hour for crystallization.
  • the temperature was lowered to room temperature at 300 ° C./hour to obtain a plate-shaped crystallized glass.
  • the precipitated crystals were analyzed, it was confirmed that a ⁇ -quartz solid solution was precipitated as the main crystal.
  • the average coefficient of thermal expansion in the temperature range of 30 ° C. to 380 ° C. was 0 / ° C.
  • the plate-shaped crystallized glass was cut into a disk shape having a diameter of 100 mm, and the surface of the plate-shaped crystallized glass was polished to a mirror surface shape.
  • the thickness of the plate-shaped crystallized glass was 0.2 mm.
  • the mirrored surface of the plate-shaped crystallized glass was measured with an atomic force microscope (AFM). As a result, Ra: 0.2 nm and TTV: 0.9 ⁇ m. From the above, a support substrate was obtained.
  • a composite is formed by directly bonding a lithium niobate crystal substrate (LN substrate) having a diameter of 100 mm and a thickness of 0.2 mm as a piezoelectric substrate to the support substrate prepared in (1) by ADB. Obtained a substrate. Specifically, a composite substrate was obtained by forming a microcrystalline metal thin film on each of the bonding surfaces of the support substrate and the piezoelectric substrate by a sputtering method and then directly bonding them under vacuum. Almost no bubbles were observed at the bonding interface between the support substrate and the LN substrate, and the bonding was good. Furthermore, the cross section of the composite substrate was observed with a scanning electron microscope (SEM). As a result, it was confirmed that there was no gap at the bonding interface and the support substrate and the LN substrate were firmly bonded.
  • SEM scanning electron microscope
  • Example 2 A lithium tantalate crystal substrate (LT substrate) as a piezoelectric substrate having a diameter of 100 mm and a thickness of 0.35 mm is bonded to the support substrate produced in the same manner as in (1) of Example 1 by SAB.
  • a microcrystalline metal thin film was formed on the surface by a sputtering method.
  • a composite substrate was obtained by activating the surfaces of each microcrystalline metal thin film to be bonded to each other using a FAB gun and then directly bonding them under vacuum.
  • a Si film (thickness 10 nm) was used as the microcrystalline metal thin film. Almost no bubbles were observed at the bonding interface between the support substrate and the LT substrate, and the bonding was good.
  • the cross section of the composite substrate was observed with a scanning electron microscope (SEM). As a result, it was confirmed that there was no gap at the bonding interface and the support substrate and the LT substrate were firmly bonded.
  • the bonding strength of the produced composite substrate was evaluated by the blade crack method. Specifically, "Bounding of silicon wafer for silicon-on-insulator" W. P. Maszara, et. Based on the method described in al Journal of Applied Physics 64, 4943 (1988), a certain amount of blades (thickness: 76 ⁇ m) are inserted into the composite interface from four locations at 90 ° intervals from the end face of the composite substrate, and the peeling length thereof. The surface energy value: ⁇ (J / m 2 ) was calculated from this. The ⁇ value was calculated by the formula shown below. L: Crack length (mm) y: 1/2 thickness ( ⁇ m) of the blade t1, t2: Thickness of each substrate ( ⁇ m) E1, E2: Young's modulus (GPa) of each substrate
  • the surface energy value of the produced composite substrate was 1.2 (J / m 2 ) on average measured at four points. As described above, the surface energy value of the composite substrate exceeds 0.7 (J / m 2 ) required for the grinding and polishing processes, and it is confirmed that the composite substrate has sufficient bonding strength. did it.
  • the piezoelectric substrate side of the composite substrate produced by the above SAB was ground and polished to make it thinner.
  • a high-rigidity grinding machine manufactured by Tokyo Seimitsu Co., Ltd.
  • the average thickness of the processed piezoelectric substrate was 1.98 ⁇ m, and the in-plane thickness variation of the piezoelectric substrate was 0.52 ⁇ m.
  • polishing was performed using a CMP apparatus (manufactured by Tokyo Seimitsu Co., Ltd.) so that the thickness of the piezoelectric substrate was about 1 ⁇ m and Ra was 0.5 nm or less. Since it has sufficient joint strength as in the case of grinding, it was possible to process without causing problems such as breakage during processing.
  • the average thickness of the processed piezoelectric substrate was 0.96 ⁇ m, the in-plane thickness variation of the piezoelectric substrate was 0.39 ⁇ m, and Ra was 0.10 nm.
  • the composite substrate was cut into a size of 1 mm ⁇ 1.5 mm.
  • a chip-shaped SAW filter was obtained. 100 samples of such a SAW filter were prepared, and the filter characteristics in the 1.05 GHz band as a frequency band were evaluated.
  • the frequency temperature characteristic was ⁇ 15 ppm / ° C. in the anti-resonant frequency region and ⁇ 5 ppm / ° C. in the resonance frequency region in the temperature range of ⁇ 40 ° C. to 100 ° C.
  • the TCF of the SAW filter using the Sialon support substrate which is a conventional technique, is generally about ⁇ 20 ppm / ° C., and the SAW filter provided with the composite substrate according to the present invention is superior to the conventional product in TCF. It could be confirmed.
  • a support substrate made of crystallized glass having a coefficient of thermal expansion of substantially 0 is used, and the piezoelectric substrate is restrained by the support substrate to prevent thermal expansion and contraction of the piezoelectric substrate. It can be made less likely to occur. Therefore, by using the composite substrates of Examples 1 and 2 for the electronic device, the frequency temperature characteristic (TCF) can be significantly improved. Therefore, the filter characteristics of the electronic device can be stabilized.
  • TCF frequency temperature characteristic

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

L'invention concerne un substrat composite qui peut améliorer la stabilité des caractéristiques de filtre contre un changement de température.　Un substrat composite 1 est un substrat composite qui est utilisé pour un dispositif électronique. Le substrat composite 1 est caractérisé en ce qu'il est pourvu d'un substrat de support 2, et d'un substrat piézoélectrique 3 qui est disposé sur le substrat de support 2, le substrat de support 2 étant formé de verre cristallisé obtenu par dépôt d'une solution solide de beta-quartz et/ou d'une solution solide de beta-eucryptite.
PCT/JP2020/005744 2019-03-15 2020-02-14 Substrat composite, dispositif électronique, procédé de fabrication de substrat composite et procédé de fabrication de dispositif électronique WO2020189115A1 (fr)

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Publication number Priority date Publication date Assignee Title
WO2023189103A1 (fr) * 2022-03-28 2023-10-05 日本碍子株式会社 Substrat composite, élément à ondes acoustiques de surface et procédé de fabrication de substrat composite
EP4122885A4 (fr) * 2021-06-09 2024-02-21 NGK Insulators, Ltd. Substrat composite et procédé de fabrication de ce substrat composite

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JP2008118576A (ja) * 2006-11-07 2008-05-22 Fujitsu Media Device Kk 弾性波デバイス
JP2014197845A (ja) * 2009-11-26 2014-10-16 株式会社村田製作所 圧電デバイス
JP2015222970A (ja) * 2011-07-29 2015-12-10 株式会社村田製作所 弾性波デバイスの製造方法
WO2016017435A1 (fr) * 2014-07-30 2016-02-04 日本電気硝子株式会社 Verre cristallisé
JP2016074598A (ja) * 2015-11-18 2016-05-12 日本電気硝子株式会社 珪酸塩ガラスの製造方法
JP2018093329A (ja) * 2016-12-01 2018-06-14 日本碍子株式会社 弾性波素子
JP2019009641A (ja) * 2017-06-26 2019-01-17 太陽誘電株式会社 弾性波共振器、フィルタおよびマルチプレクサ
JP2019029941A (ja) * 2017-08-02 2019-02-21 株式会社ディスコ 弾性波デバイス用基板の製造方法

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Publication number Priority date Publication date Assignee Title
JP2001052334A (ja) * 1999-08-04 2001-02-23 Okamoto Glass Co Ltd 磁気ディスク用基板素材およびその製造法
JP2008118576A (ja) * 2006-11-07 2008-05-22 Fujitsu Media Device Kk 弾性波デバイス
JP2014197845A (ja) * 2009-11-26 2014-10-16 株式会社村田製作所 圧電デバイス
JP2015222970A (ja) * 2011-07-29 2015-12-10 株式会社村田製作所 弾性波デバイスの製造方法
WO2016017435A1 (fr) * 2014-07-30 2016-02-04 日本電気硝子株式会社 Verre cristallisé
JP2016074598A (ja) * 2015-11-18 2016-05-12 日本電気硝子株式会社 珪酸塩ガラスの製造方法
JP2018093329A (ja) * 2016-12-01 2018-06-14 日本碍子株式会社 弾性波素子
JP2019009641A (ja) * 2017-06-26 2019-01-17 太陽誘電株式会社 弾性波共振器、フィルタおよびマルチプレクサ
JP2019029941A (ja) * 2017-08-02 2019-02-21 株式会社ディスコ 弾性波デバイス用基板の製造方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4122885A4 (fr) * 2021-06-09 2024-02-21 NGK Insulators, Ltd. Substrat composite et procédé de fabrication de ce substrat composite
WO2023189103A1 (fr) * 2022-03-28 2023-10-05 日本碍子株式会社 Substrat composite, élément à ondes acoustiques de surface et procédé de fabrication de substrat composite

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