WO2023171715A1 - Dispositif à ondes élastiques, filtre de dérivation, dispositif de communication et procédé de fabrication de dispositif à ondes élastiques - Google Patents

Dispositif à ondes élastiques, filtre de dérivation, dispositif de communication et procédé de fabrication de dispositif à ondes élastiques Download PDF

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WO2023171715A1
WO2023171715A1 PCT/JP2023/008866 JP2023008866W WO2023171715A1 WO 2023171715 A1 WO2023171715 A1 WO 2023171715A1 JP 2023008866 W JP2023008866 W JP 2023008866W WO 2023171715 A1 WO2023171715 A1 WO 2023171715A1
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acoustic impedance
impedance layer
elastic wave
wave device
range
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PCT/JP2023/008866
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English (en)
Japanese (ja)
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雅樹 南部
惣一朗 野添
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京セラ株式会社
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Publication of WO2023171715A1 publication Critical patent/WO2023171715A1/fr

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    • 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
    • H03H9/25—Constructional features of resonators 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
    • H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H9/72—Networks using surface acoustic waves

Definitions

  • the present disclosure relates to an elastic wave device that uses elastic waves, a duplexer including the elastic wave device, a communication device including the elastic wave device, and a method for manufacturing the elastic wave device.
  • Patent Document 1 discloses an elastic wave device including an acoustic reflection film configured of a plurality of acoustic impedance layers including a low acoustic impedance layer with a relatively low acoustic impedance and a high acoustic impedance layer with a relatively high acoustic impedance. is disclosed.
  • the acoustic reflection film includes a first acoustic impedance layer that is one of the plurality of acoustic impedance layers, and a first acoustic impedance layer that is one of the plurality of acoustic impedance layers.
  • the second acoustic impedance layer is an acoustic impedance layer and has a different arithmetic mean roughness (Ra) from the first acoustic impedance layer, thereby effectively reducing unnecessary waves.
  • An elastic wave device includes a piezoelectric substrate, a support substrate, and an acoustic multilayer film located between the piezoelectric substrate and the support substrate, and the acoustic multilayer film includes a plurality of low acoustic impedance layers.
  • the acoustic impedance of the high acoustic impedance layer is higher than the acoustic impedance of the low acoustic impedance layer, and the arithmetic of the interface of the high acoustic impedance layer on the supporting substrate side
  • the average roughness is within a predetermined first range that does not include 0 nm.
  • a duplexer includes an antenna terminal, a transmission filter that filters a signal output to the antenna terminal, and a reception filter that filters a signal input from the antenna terminal. At least one of the filter and the reception filter includes the above elastic wave device.
  • a communication device includes an antenna, the above-mentioned duplexer having an antenna terminal connected to the antenna, and an IC connected to a transmission filter and a reception filter.
  • a method for manufacturing an acoustic wave device includes a first step of providing an acoustic multilayer film on a first surface side of a piezoelectric substrate, and a supporting substrate on a surface of the acoustic multilayer film opposite to the piezoelectric substrate.
  • a second step of providing a low acoustic impedance layer includes a third step of providing a low acoustic impedance layer; a fourth step of providing a high acoustic impedance layer having higher acoustic impedance than the low acoustic impedance layer; a fifth step of performing a smoothing treatment on the surface of the acoustic impedance layer that is far from the piezoelectric substrate or the surface of the high acoustic impedance layer that is close to the piezoelectric substrate; The fourth step and the fifth step are repeated at least twice.
  • FIG. 1 is a schematic cross-sectional view of an elastic wave device according to an embodiment of the present disclosure.
  • FIG. 1 is a schematic plan view of an elastic wave device according to an embodiment of the present disclosure.
  • FIG. 3 is a diagram comparing frequency characteristics of an elastic wave device according to an embodiment of the present disclosure and a comparative example.
  • FIG. 3 is a diagram comparing frequency characteristics of an elastic wave device according to an embodiment of the present disclosure and a comparative example.
  • FIG. 1 is a schematic cross-sectional view of an elastic wave device according to an embodiment of the present disclosure.
  • FIG. 3 is a diagram comparing frequency characteristics of an elastic wave device according to an embodiment of the present disclosure and a comparative example.
  • FIG. 1 is a schematic cross-sectional view of an elastic wave device according to an embodiment of the present disclosure.
  • FIG. 3 is a diagram comparing frequency characteristics of an elastic wave device according to an embodiment of the present disclosure and a comparative example.
  • FIG. 3 is a schematic cross-sectional view of an elastic wave device according to a modification example of the present disclosure.
  • 1 is a diagram schematically showing a duplexer as a usage example of an elastic wave device according to an embodiment of the present disclosure.
  • 11 is a block diagram showing a main part configuration of a communication device as an example of using the duplexer of FIG. 10.
  • FIG. FIG. 1 is a diagram illustrating a method of manufacturing an elastic wave device according to an embodiment of the present disclosure.
  • an orthogonal coordinate system consisting of an X-axis, a Y-axis, and a Z-axis may be attached to the drawings.
  • either direction may be upward or downward.
  • the term upper surface or lower surface may be used with the Z-axis direction as the vertical direction.
  • the X-axis is defined to be parallel to the propagation direction of elastic waves propagating along the upper surface of the piezoelectric substrate 2, which will be described later.
  • the Y-axis is defined to be parallel to the top surface of the piezoelectric substrate 2 and perpendicular to the X-axis.
  • the Z-axis is defined to be perpendicular to the top surface of the piezoelectric substrate 2.
  • FIG. 1 is a schematic cross-sectional view of an elastic wave device 1 according to an embodiment of the present disclosure.
  • the elastic wave device 1 includes a piezoelectric substrate 2, an acoustic multilayer film 4, and a support substrate 3. Furthermore, an IDT (Interdigital Transducer) electrode 5 is located on the upper surface of the piezoelectric substrate 2 .
  • IDT Interdigital Transducer
  • the thickness of the support substrate 3 is not particularly limited, but is, for example, thicker than the thickness of the piezoelectric substrate 2 described later.
  • the material of the support substrate 3 is not particularly limited as long as it has a certain level of strength.
  • the support substrate 3 is made of a material with a smaller coefficient of linear expansion than the piezoelectric substrate 2, it is possible to reduce the deformation of the piezoelectric substrate 2 due to temperature changes, thereby reducing characteristic changes due to temperature changes. I can do it.
  • the material of the support substrate 3 may be a material in which the transverse wave sonic velocity of the elastic wave propagating is higher than the transverse wave sonic velocity of the elastic wave propagating through the piezoelectric substrate 2 .
  • the elastic waves can be confined in the piezoelectric substrate 2. , it is possible to provide an elastic wave device 1 with excellent frequency characteristics.
  • Examples of the material for the support substrate 3 include sapphire (Al 2 O 3 ) and silicon (Si). In one embodiment of the present disclosure, a case where Si is used as the support substrate 3 will be described as an example.
  • the piezoelectric substrate 2 has an upper surface and a lower surface perpendicular to the Z-axis, with the Z-axis being the vertical direction.
  • an acoustic multilayer film 4 which will be described later, and the above-mentioned support substrate 3 are located, and on the upper surface of the piezoelectric substrate 2, an IDT electrode 5, which will be described later, is located.
  • the piezoelectric substrate 2 As the material of the piezoelectric substrate 2, for example, a piezoelectric single crystal substrate containing lithium tantalate (LiTaO 3 ) crystal, a piezoelectric single crystal substrate containing lithium niobate (LiNbO 3 ) crystal, etc. are used. be able to. Specifically, in the embodiment of the present disclosure, the piezoelectric substrate 2 is made of LiTaO 3 .
  • the thickness of the piezoelectric substrate 2 is not particularly limited, but may be thinner than the thickness of the support substrate 3 described above, for example. Moreover, it may be thicker than the low acoustic impedance layer 42 and the high acoustic impedance layer 41 of the acoustic multilayer film 4 described later. As an example, the thickness of the piezoelectric substrate 2 is 100 nm to 1000 nm.
  • the lower surface of the piezoelectric substrate 2 and the acoustic multilayer film 4 may be in direct contact with each other, or may be in indirect contact with each other via an intermediate layer (not shown), for example.
  • Examples of such an intermediate layer include insulating materials such as silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ), and aluminum oxide (Al 2 O 3 ). By providing such an insulating intermediate layer, it is possible to reduce the formation of unnecessary potentials and unnecessary capacitances, and it is possible to improve the electrical characteristics of the acoustic wave device 1.
  • insulating materials such as silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ), and aluminum oxide (Al 2 O 3 ).
  • the acoustic multilayer film 4 is located between the piezoelectric substrate 2 and the support substrate 3.
  • low acoustic impedance layers 42 and high acoustic impedance layers 41 are alternately laminated.
  • the acoustic impedance of the low acoustic impedance layer 42 is lower than the acoustic impedance of the piezoelectric substrate 2
  • the acoustic impedance of the high acoustic impedance layer 41 is higher than the acoustic impedance of the low acoustic impedance layer 42 .
  • each low acoustic impedance layer 42 may be made of different materials. Specifically, in embodiments of the present disclosure, low acoustic impedance layer 42 is SiO2 .
  • Materials for the high acoustic impedance layer 41 include Si 3 N 4 , Al 2 O 3 , platinum (Pt), aluminum nitride (AlN), titanium oxide (TiO 2 ), tantalum oxide (Ta 2 O 5 ), and hafnium oxide (HfO). 2 ), zirconium oxide (ZrO 2 ), tungsten (W), LiTaO 3 , LiNbO 3 , and the like. Furthermore, when having a plurality of high acoustic impedance layers 41, each high acoustic impedance layer 41 may be made of different materials. Further, the same high acoustic impedance layer 41 may include a plurality of materials. Specifically, in embodiments of the present disclosure, high acoustic impedance layer 41 includes HfO 2 and ZrO 2 .
  • the number of laminated low acoustic impedance layers 42 and high acoustic impedance layers 41 may be set as appropriate. In one embodiment of the present disclosure, specifically, there are four low acoustic impedance layers 42 and four high acoustic impedance layers 41.
  • the acoustic multilayer film 4 has a plurality of high acoustic impedance layers 41, the high acoustic impedance layers 41a, 41b, 41c, and 41d are arranged in order from the layer closest to the piezoelectric substrate 2.
  • the layers 42a, 42b, 42c, and 42d are arranged in order from the layer closest to the piezoelectric substrate 2.
  • the low acoustic impedance layer 42a is located closer to the piezoelectric substrate 2 than the high acoustic impedance layer 41a.
  • the arithmetic mean roughness of the low acoustic impedance layer 42 at the interface on the supporting substrate side is defined as Ra2. Further, the arithmetic mean roughness of the high acoustic impedance layer 41 at the interface on the support substrate side is defined as Ra1.
  • the arithmetic mean roughness of the interface of the low acoustic impedance layer 42 on the support substrate side may be simply referred to as the arithmetic mean roughness of the low acoustic impedance layer 42.
  • the arithmetic mean roughness of the interface of the high acoustic impedance layer 41 on the support substrate side may be simply referred to as the arithmetic mean roughness of the high acoustic impedance layer 41.
  • the arithmetic mean roughness refers to the arithmetic mean roughness (Ra) defined in JIS B 0601:2013.
  • the arithmetic mean roughness of the low acoustic impedance layers 42a, 42b, 42c, and 42d are defined as Ra2a, Ra2b, Ra2c, and Ra2d, respectively.
  • the arithmetic mean roughness of the high acoustic impedance layers 41a, 41b, 41c, and 41d are defined as Ra1a, Ra1b, Ra1c, and Ra1d, respectively. do.
  • the support substrate 3 may have a void on the upper surface.
  • the piezoelectric substrate 2 covers the gap of the support substrate 3 in plan view, leaving a space inside the gap.
  • the size and depth of the cavity may be set as appropriate.
  • a substrate (not shown) or the like may be provided on the upper surface side of the support substrate 3 having a void.
  • the IDT electrode 5 may be located on the top surface of the piezoelectric substrate 2.
  • the IDT electrode 5 is made of a conductive material.
  • the IDT electrode 5 can be made of various conductive materials such as Al, Cu, Pt, Mo, Au, or an alloy thereof, and may also be constructed by laminating a plurality of these layers. .
  • a base layer (not shown) may be interposed at the interface between the stacks.
  • FIG. 2 is a plan view of the elastic wave device 1 according to an embodiment of the present disclosure, viewed from the Z-axis direction.
  • the IDT electrode 5 constitutes a resonator having, for example, a pair of comb-shaped electrodes 51a and 51b.
  • the comb-teeth electrodes 51a and 51b may be collectively referred to as the comb-teeth electrode 51.
  • the comb-shaped electrode 51 includes two bus bars 511 and a plurality of long electrode fingers 512 connected to either bus bar 511. Electrode fingers 512a connected to one bus bar 511a and electrode fingers 512b connected to the other bus bar 511b are alternately arranged.
  • the comb-shaped electrode 51 may include a plurality of dummy electrodes 513 facing the tips of electrode fingers 512 connected to one bus bar 511 and connected to the other bus bar 511.
  • the lengths of the plurality of electrode fingers 512 are, for example, equal to each other.
  • the IDT electrode 5 may be subjected to so-called apodization, in which the length of the plurality of electrode fingers 512 changes depending on the position in the propagation direction. Further, the length and thickness of the electrode fingers 512 may be set as appropriate depending on required electrical characteristics and the like. From another perspective, the length of the plurality of electrode fingers 512 is the intersection width.
  • the repetition interval of the electrode fingers 512a and 512b is defined as the electrode finger pitch p, and the width of the electrode finger 512 is defined as the electrode finger width w.
  • the electrode finger pitch p and electrode finger width w of the IDT electrode 5 may be designed as appropriate depending on desired frequency characteristics.
  • the electrode finger pitch p of the IDT electrode 5 is constant, but is not limited to this example.
  • the pitch p may be designed to gradually increase, or may be designed to have a plurality of types of pitches in stages.
  • a SAW Surface Acoustic Wave
  • the resonant frequency fr of the elastic wave device 1 is approximately equal to the frequency of the excited SAW.
  • the anti-resonance frequency fa is determined by the resonance frequency fr and the capacitance ratio, and the capacitance ratio is mainly defined by the piezoelectric substrate 2 and adjusted by the number of electrode fingers 512, crossing width, film thickness, etc.
  • a pair of reflectors 52 may be located on both sides of the IDT electrode 5 in the SAW propagation direction.
  • the reflector 52 includes a pair of reflector bus bars facing each other and a plurality of strip electrodes extending between the pair of reflector bus bars. Further, the number of strip electrodes of the reflector 52 may be designed as appropriate.
  • the arithmetic mean roughness Ra1a, Ra1b, Ra1c, and Ra1d of the high acoustic impedance layer 41 are predetermined first numerical values. Furthermore, the arithmetic mean roughness Ra2a, Ra2b, Ra2c, and Ra2d of the low acoustic impedance layer 42 are predetermined second numerical values. In one embodiment of the disclosure, the first numerical value is greater than the second numerical value.
  • the first numerical value does not need to be strictly the same numerical value and may include manufacturing errors.
  • the manufacturing error in the first numerical value refers to an error in a range corresponding to 30% of the average value of the first numerical value.
  • the first numerical value may be in the range of 0.70 ⁇ average first numerical value to 1.30 ⁇ average first numerical value.
  • the range that the first numerical value can take in this way is called the first range.
  • the second numerical value does not need to be strictly the same numerical value, and may include manufacturing errors.
  • the manufacturing error in the second numerical value refers to an error in a range corresponding to 30% of the average value of the second numerical value.
  • the second numerical value may be in the range of 0.70 ⁇ average second numerical value to 1.30 ⁇ average second numerical value.
  • the range that the second numerical value can take in this way is called a second range.
  • FIG. 3 is a diagram comparing simulation results of frequency characteristics for Example 1, Comparative Example 1, and Comparative Example 2 in the elastic wave device 1 of the present disclosure.
  • FIG. 3A shows frequency characteristics in the range of 4500 MHz to 8500 HMz
  • FIGS. 3B to 3F are partially enlarged views of FIG. 3A.
  • Example 1 the arithmetic mean roughness Ra2a, Ra2b, Ra2c, and Ra2d of the low acoustic impedance layer 42 are 0 nm, and the arithmetic mean roughness Ra1a, Ra1b, Ra1c, and Ra1d of the high acoustic impedance layer 41 are 35 nm. .
  • the first numerical value is 35 nm and the second numerical value is 0 nm.
  • the first numerical value may be set larger than the second numerical value.
  • the arithmetic mean roughness Ra2a, Ra2b, Ra2c, and Ra2d of the low acoustic impedance layer 42 are 0 nm. Further, regarding the arithmetic mean roughness of each high acoustic impedance layer 41, the closer the high acoustic impedance layer 41 is to the support substrate 3, the larger the value of Ra1 becomes. Specifically, in Comparative Example 1, Ra1a is 35 nm, Ra1b is 47 nm, Ra1c is 58 nm, and Ra1d is 70 nm.
  • the arithmetic mean roughness Ra1a, Ra1b, Ra1c, and Ra1d of the high acoustic impedance layer 41 are 0 nm
  • the arithmetic mean roughness Ra2a, Ra2b, Ra2c, and Ra2d of the low acoustic impedance layer 42 are 35 nm. .
  • Example 1 improves the loss of the main resonance characteristics and reduces the intensity of spurious waves located on the high frequency side of the main resonance. I found out that it was getting smaller. For example, when looking at the intensity of spurious signals generated around 7000-7250 MHz, it can be seen that Example 1 is smaller than Comparative Examples 1 and 2.
  • Example 1 and Comparative Example 1-4 differ in the arithmetic mean roughness of the high acoustic impedance layer 41 and the low acoustic impedance layer 42, but the other conditions are the same.
  • the main resonance mode is a mode of the elastic wave to be used, and may be set as appropriate.
  • the main resonant mode is a Lamb wave A1 mode.
  • FIG. 4 is a diagram comparing simulation results of frequency characteristics for Example 1, Comparative Example 3, and Comparative Example 4 in the elastic wave device 1 of the present disclosure.
  • FIG. 4A shows frequency characteristics in the range of 4500 MHz to 8500 HMz
  • FIGS. 4B to 4F are partially enlarged views of FIG. 4A.
  • the arithmetic mean roughnesses Ra2a, Ra2b, Ra2c, and Ra2d of the low acoustic impedance layer 42 are 0 nm, and the arithmetic mean roughnesses of the high acoustic impedance layer 41 are different.
  • Ra1a is 70 nm
  • Ra1b is 45 nm
  • Ra1c is 25 nm
  • Ra1d is 0 nm
  • Ra1a is 0 nm
  • Ra1b is 25 nm
  • Ra1c is 45 nm
  • Ra1d is 70 nm.
  • Example 1 the loss in the main resonance characteristic is smaller than in Comparative Example 3, and the spurious loss located on the high frequency side of the main resonance is smaller than in Comparative Example 4. strength becomes smaller.
  • the arithmetic mean roughness Ra1 of the high acoustic impedance layer 41 is 35 nm, but is not limited to this example.
  • the arithmetic mean roughness Ra1 of the high acoustic impedance layer 41 may be set as appropriate.
  • the first numerical value may be set as appropriate.
  • the first numerical value may be a predetermined numerical value in the range of 0.5 nm to 70 nm.
  • the first numerical value may be a predetermined numerical value in the range of 0.7 nm to 4.0 nm.
  • the arithmetic mean roughness Ra2 of the low acoustic impedance layer 42 is 0 nm, but is not limited to this example.
  • the arithmetic mean roughness Ra2 of the low acoustic impedance layer 42 may be set as appropriate.
  • the second numerical value may be set as appropriate.
  • the second numerical value may be a predetermined numerical value in the range of 0.01 nm to 1.0 nm.
  • the second numerical value may be a predetermined numerical value in the range of 0.2 nm to 0.5 nm.
  • Example 1 the first numerical value was within the first range including the predetermined manufacturing error, and the second numerical value was within the second range including the predetermined manufacturing error. but not limited to.
  • the first range and the second range may be wider than a range that includes manufacturing errors.
  • the arithmetic mean roughness of the high acoustic impedance layer 41 is appropriately set within a predetermined first range
  • the arithmetic mean roughness of the low acoustic impedance layer 42 is appropriately set within a predetermined first range.
  • the roughness is appropriately set within a predetermined second range.
  • FIG. 6 is a diagram comparing simulation results of frequency characteristics for Example 2, Comparative Example 1, and Comparative Example 2 in the elastic wave device 1.
  • FIG. 6A shows frequency characteristics in the range of 4500 MHz to 8500 HMz
  • FIGS. 6B to 6F are partially enlarged views of FIG. 6A.
  • the arithmetic mean roughness of the high acoustic impedance layer 41 is 35 nm for Ra1a, 30 nm for Ra1b, 35 nm for Ra1c, and 30 nm for Ra1d, and the first range is 30 nm to 35 nm.
  • the arithmetic mean roughness Ra2a of the low acoustic impedance layer 42 is 0 nm, Ra2b is 5 nm, Ra2c is 0 nm, and Ra2d is 5 nm, and the second range is 0 nm to 5 nm.
  • the first range is a range that does not include 0 nm, and the lower limit of the first range is set larger than the upper limit of the second range.
  • Example 2 improves the loss of the main resonance characteristics and reduces the intensity of spurious waves located on the high frequency side of the main resonance. I found out that it was getting smaller. For example, looking at the intensity of the spurious generated around 7000-7250 MHz, it can be seen that it is smaller in Example 2 than in Comparative Examples 1 and 2.
  • the influence of the spurious mode which is an unnecessary wave, can be reduced while maintaining the characteristics of the main resonance mode of the elastic wave, as in the first embodiment. be able to.
  • the first range of the arithmetic mean roughness of the high acoustic impedance layer 41 is 30 nm to 35 nm, but is not limited to this example.
  • the first range of the high acoustic impedance layer 41 may be set as appropriate.
  • the first range may be a predetermined range from 0.5 nm to 70 nm.
  • the first range may be from 0.7 nm to 4.0 nm.
  • the second range of the arithmetic mean roughness of the low acoustic impedance layer 42 is 0 nm to 5 nm, but is not limited to this example.
  • the second range of the low acoustic impedance layer 42 may be set as appropriate.
  • the second range may be a predetermined range of 0.01 nm to 1.0 nm.
  • the second range may be 0.2 nm to 0.5 nm.
  • Example 2 the arithmetic mean roughness Ra1 of the high acoustic impedance layer 41 and the arithmetic mean roughness Ra2 of the low acoustic impedance were within predetermined ranges, but are not limited to this example.
  • the arithmetic mean roughness of each layer of the acoustic multilayer film 4 may increase as the layer is closer to the support substrate 3.
  • Example 3 the arithmetic mean roughness of the high acoustic impedance layer 41 on the support substrate 3 side is larger than the arithmetic mean roughness of the high acoustic impedance layer 41 on the piezoelectric substrate 2 side, and The arithmetic mean roughness of the support substrate 3 side is larger than the arithmetic mean roughness of the low acoustic impedance layer 42 on the piezoelectric substrate 2 side.
  • FIG. 8 is a diagram comparing simulation results of frequency characteristics for Example 3, Comparative Example 5, and Comparative Example 6 in the elastic wave device 1.
  • FIG. 8A shows frequency characteristics in the range of 4500 MHz to 8500 HMz
  • FIGS. 8B to 8F are partially enlarged views of FIG. 8A.
  • the arithmetic mean roughness of the high acoustic impedance layer 41 is 14 nm for Ra1a, 21 nm for Ra1b, 28 nm for Ra1c, and 35 nm for Ra1d. Further, in Example 3, the arithmetic mean roughness Ra2a of the low acoustic impedance layer 42 is 10 nm, Ra2b is 17 nm, Ra2c is 24 nm, and Ra2d is 31 nm.
  • the arithmetic mean roughness of the high acoustic impedance layer 41 is 31 nm for Ra1a, 24 nm for Ra1b, 17 nm for Ra1c, and 10 nm for Ra1d. Further, in Example 3, the arithmetic mean roughness Ra2a of the low acoustic impedance layer 42 is 35 nm, Ra2b is 28 nm, Ra2c is 21 nm, and Ra2d is 14 nm.
  • the arithmetic mean roughness of the high acoustic impedance layer 41 is 0 nm for all Ra1a, Ra1b, Ra1c, and Ra1d. Further, in Example 3, the arithmetic mean roughness Ra2a, Ra2b, Ra2c, and Ra2d of the low acoustic impedance layer 42 are all 0 nm.
  • Example 3 the intensity of the spurious located on the high frequency side of the main resonance is smaller than in Comparative Example 6, and the main resonance characteristics are lower than in Comparative Example 4. I could see that Ross was improving.
  • the arithmetic mean roughness of the high acoustic impedance layer 41 and the arithmetic mean roughness of the low acoustic impedance layer 42 in Example 3 are not limited to the above example. If the arithmetic mean roughness of each layer of the acoustic multilayer film 4 increases as the layer is closer to the support substrate 3, the arithmetic mean roughness of each layer may be set appropriately.
  • the arithmetic mean roughness of the acoustic impedance layer 41 is 1.4 nm for Ra1a, 2.1 nm for Ra1b, 2.8 nm for Ra1c, and 3.5 nm for Ra1d
  • the arithmetic mean roughness of the low acoustic impedance layer 42 Ra2a may be 1.0 nm
  • Ra2b may be 1.7 nm
  • Ra2c may be 2.4 nm
  • Ra2d may be 3.1 nm.
  • FIG. 9 shows a modification of Example 1-3 of the present disclosure.
  • 9A is a modification of the first embodiment
  • FIG. 9B is a modification of the second embodiment
  • FIG. 9C is a modification of the third embodiment.
  • a bonding layer 43 may be located between the acoustic multilayer film 4 and the support substrate 3.
  • the thickness and material of the bonding layer 43 are set appropriately.
  • the bonding layer 43 may include the same material as the low acoustic impedance layer 42 or the same material as the high acoustic impedance layer 41.
  • the arithmetic mean roughness Ra3 of the interface between the bonding layer 43 and the support substrate 3 may be set as appropriate, and may be 0 nm, for example.
  • the bonding layer 43 has such a configuration, the bonding strength at the interface between the bonding layer 43 and the support substrate 3 is improved, and the bonding strength between the acoustic multilayer film 4 and the support substrate 3 can be improved.
  • the arithmetic mean roughness Ra3 at the bonding interface between the bonding layer 43 and the support substrate 3 is equal to the arithmetic mean roughness of the other low acoustic impedance layer 42.
  • Ra2a, Ra2b, Ra2c, and Ra2d may be different numerical values.
  • the arithmetic mean roughness Ra3 of the bonding layer 43 may be a different value from the predetermined second numerical value satisfied by the arithmetic mean roughnesses Ra2a, Ra2b, Ra2c, and Ra2d of the low acoustic impedance layer 42.
  • Ra3 may be a numerical value that is not included in the predetermined second range satisfied by the arithmetic mean roughnesses Ra2a, Ra2b, Ra2c, and Ra2d of the other low acoustic impedance layers 42.
  • Example 1-3 had a SAW resonator configuration
  • the present invention is not limited to this example.
  • the SAW resonator may be a plate wave device.
  • the elastic wave device 1 may be a BAW resonator.
  • the acoustic wave device 1 is a BAW resonator
  • the acoustic wave device 1 has an upper electrode on the upper surface side of the piezoelectric substrate 2 and a lower electrode on the lower surface side instead of the IDT electrode 5.
  • the BAW resonator may be a so-called XBAR device.
  • an IDT electrode is provided on the upper surface side of the piezoelectric substrate 2.
  • the acoustic multilayer film 4 is located on the lower surface side of the lower electrode.
  • FIG. 10 is a circuit diagram schematically showing the configuration of a duplexer 101 as an example of how the elastic wave device 1 is used.
  • the comb-shaped electrode 51 is schematically shown in the form of a two-pronged fork, and the reflector 52 is a single piece with bent ends. It is represented by a line.
  • the duplexer 101 includes, for example, a transmission filter 105 that filters a transmission signal from a transmission terminal 103 and outputs it to an antenna terminal 102, and a transmission filter 105 that filters a reception signal from an antenna terminal 102 and outputs it to a pair of reception terminals 104. It has a reception filter 106.
  • the elastic wave device 1 may be used as at least one of the transmission filter 105 and the reception filter 106. Furthermore, the elastic wave device 1 may be used as both the transmission filter 105 and the reception filter 106.
  • the transmission filter 105 may be configured, for example, by a ladder-type filter in which a plurality of resonators are connected in a ladder-type. That is, the transmission filter 105 includes a plurality of resonators or one resonator connected in series between the transmission terminal 103 and the antenna terminal 102, and a plurality of resonators connecting the series arm, which is a series line, to a reference potential. resonator or one resonator in parallel arms.
  • the reception filter 106 may be configured to include, for example, a resonator and a multimode filter 107.
  • the multimode filter 11 includes a plurality of IDT electrodes 5 arranged in the propagation direction of elastic waves and a pair of reflectors 52 arranged on both sides of the IDT electrodes 5. It is assumed that the multimode filter 107 includes a double mode filter. In the illustrated example, the number of IDT electrodes 5 is three.
  • FIG. 10 is just an example of the configuration of the duplexer 101, and the configuration is not limited to this example.
  • the receiving filter 106 may be configured by a ladder type filter like the transmitting filter 105.
  • both the transmission filter 105 and the reception filter 106 are elastic wave filters including elastic wave resonators, but the present invention is not limited to this example.
  • one of the transmission filter 105 and the reception filter 106 may be an LC filter including one or more inductors and one or more capacitors.
  • the duplexer 101 may be a diplexer or a multiplexer including three or more filters.
  • FIG. 11 is a block diagram showing the main parts of a communication device 111 as an example of how the duplexer 101 is used.
  • the communication device 111 performs wireless communication using radio waves, and includes a duplexer 101.
  • a transmission information signal TIS containing information to be transmitted is modulated and frequency-increased by an RF-IC (Radio Frequency-Integrated Circuit) 113 to become a transmission signal TS. Raising the frequency can also be referred to as converting the carrier frequency to a high frequency signal.
  • the transmission signal TS has unnecessary components outside the transmission passband removed by the bandpass filter 115a, is amplified by the amplifier 114a, and is input to the duplexer 101 (transmission terminal 103). Then, the duplexer 101 (transmission filter 105) removes unnecessary components other than the transmission passband from the input transmission signal TS, and outputs the removed transmission signal TS from the antenna terminal 102 to the antenna 112. .
  • the antenna 112 converts an input electrical signal (transmission signal TS) into a wireless signal (radio wave) and transmits the signal.
  • a wireless signal (radio wave) received by the antenna 112 is converted into an electric signal (received signal RS) by the antenna 112, and input to the duplexer 101 (antenna terminal 102).
  • the duplexer 101 (reception filter 106) removes unnecessary components outside the reception passband from the input reception signal RS, and outputs the result from the reception terminal 104 to the amplifier 114b.
  • the output received signal RS is amplified by the amplifier 114b, and unnecessary components outside the receiving passband are removed by the bandpass filter 115b. Then, the received signal RS is lowered in frequency and demodulated by the RF-IC 113 to become a received information signal RIS.
  • the transmitted information signal TIS and the received information signal RIS may be low frequency signals (baseband signals) containing appropriate information, such as analog audio signals or digitized audio signals.
  • the pass band of the wireless signal may be set as appropriate, and in this embodiment, a relatively high frequency pass band of 5 GHz or higher is also possible, for example.
  • the modulation method may be phase modulation, amplitude modulation, frequency modulation, or a combination of two or more of these.
  • FIG. 11 schematically shows only the main parts, and a low-pass filter or isolator or the like may be added at an appropriate position, or the position of an amplifier or the like may be changed.
  • One manufacturing method of the present disclosure for an acoustic wave device 1 includes a first step of providing an acoustic multilayer film 4 on one of the two main surfaces of a prepared first substrate, and a first step of providing an acoustic multilayer film 4 on one of the two main surfaces of a prepared first substrate. and a second step of providing a second substrate containing a material different from the material of the first substrate on a surface opposite to the first substrate.
  • a first substrate containing an arbitrary material is prepared.
  • the first substrate may be the piezoelectric substrate 2 having piezoelectricity, or the support substrate 3.
  • FIG. 12A shows an example in which a piezoelectric substrate 2 is prepared as the first substrate.
  • a first acoustic impedance layer is formed on one of the two main surfaces of the first substrate.
  • the thickness of the first acoustic impedance layer may be 100 nm to 300 nm, for example.
  • FIG. 12B shows an example in which a low acoustic impedance layer 42a is formed as the first acoustic impedance layer.
  • the step of forming the first acoustic impedance layer in this manner is referred to as the third step.
  • main surface A the main surface that is closer to the first substrate
  • main surface B the main surface that is farther away
  • the arithmetic mean roughness of the main surface B of the first acoustic impedance layer is relatively larger than that of the main surface A because the interface of the main surface B of the first acoustic impedance layer becomes rough depending on the film forming conditions and the like.
  • a smoothing process is performed on the main surface B of the first acoustic impedance layer.
  • the method of performing the smoothing process there are no particular limitations on the method of performing the smoothing process.
  • an etching method using an ion beam or plasma can be exemplified.
  • the arithmetic mean roughness of the main surface B of the first acoustic impedance layer can be set to 0.01 nm to 1.0 nm.
  • the step of performing the smoothing treatment on the main surface of the first acoustic impedance layer on the side far from the first substrate is referred to as the fifth step.
  • the third step of forming the first acoustic impedance layer and the fifth step of performing a smoothing process on the main surface B of the first acoustic impedance layer may be performed in order or may be performed simultaneously.
  • a second acoustic impedance layer is formed on the main surface B of the first acoustic impedance layer.
  • the acoustic impedance of the second acoustic impedance layer is different from the acoustic impedance of the first acoustic impedance layer.
  • An example of the thickness of the second acoustic impedance layer is 100 nm to 300 nm.
  • FIG. 12D shows an example in which a high acoustic impedance layer 41a is formed as the second acoustic impedance layer.
  • the step of forming the second acoustic impedance layer in this manner is referred to as the fourth step.
  • the main surface that is closer to the first substrate is called main surface C
  • the main surface that is farther away is called main surface D.
  • the main surface B of the first acoustic impedance layer and the main surface C of the second acoustic impedance layer are joined.
  • the arithmetic mean roughness of the main surface D is larger than that of the main surface C.
  • the main surface D may be roughened by etching using an ion beam or plasma, or by forming a second acoustic impedance layer.
  • the arithmetic mean roughness of the principal surface D may be increased depending on the film conditions and the like. Moreover, when the second acoustic impedance layer contains multiple types of oxides, the high acoustic impedance layer 41a is made of a composite oxide, thereby making it possible to increase the arithmetic mean roughness of the principal surface D.
  • the main surface D is not subjected to surface roughening treatment, and the arithmetic mean roughness of the main surface D is adjusted according to the film formation conditions of the second acoustic impedance layer.
  • the arithmetic mean roughness of the main surface B of the first acoustic impedance layer is approximately 0.01 nm to 1.0 nm
  • the second acoustic impedance layer is formed under approximately the same conditions as the first acoustic impedance layer.
  • the main surface D will be approximately 0.5 nm to 4.0 nm.
  • the first acoustic impedance layer is again formed on the main surface D of the second acoustic impedance layer.
  • a low acoustic impedance layer 42b which is the first acoustic impedance layer
  • the main surface D of the high acoustic impedance layer 41a which is the second acoustic impedance layer.
  • main surface E the main surface that is closer to the first substrate
  • main surface F main surface F.
  • the main surface F of the first acoustic impedance layer is smoothed again, and as a fourth step, the main surface F of the first acoustic impedance layer Then, a second acoustic impedance layer is formed again.
  • a second substrate made of an arbitrary material is provided on the acoustic multilayer film 4 obtained by repeating the third, fourth, and fifth steps.
  • This step is called the second step.
  • FIG. 12F shows a case where the second substrate is the support substrate 3, the present invention is not limited to this example.
  • the first substrate is the support substrate 3, the second substrate may be the piezoelectric substrate 2.
  • the third step, fourth step, and fifth step are repeated three times in FIG. 12F, the present invention is not limited to this example.
  • the third step, the fourth step, and the fifth step can be repeated at least one arbitrary number of times.
  • a step of forming a bonding layer 43 on the acoustic multilayer film 4 may be included.
  • the step of polishing the main surface opposite to the main surface on which the acoustic multilayer film 4 is located may be included.
  • the first substrate is the piezoelectric substrate 2
  • the thickness of the piezoelectric substrate 2 can be appropriately designed and the frequency characteristics can be adjusted by polishing. For example, polishing may be performed until the first substrate has a thickness of 100 nm to 1000 nm. There are no particular limitations on the method of polishing.
  • a first substrate, a second substrate, a first acoustic impedance layer, and a second acoustic impedance layer are respectively a piezoelectric substrate 2, a supporting substrate 3, a low acoustic impedance layer 42, and a high acoustic impedance layer 41.
  • the first substrate, the second substrate, the first acoustic impedance layer, and the second acoustic impedance layer are the supporting substrate 3, the piezoelectric substrate 2, the high acoustic impedance layer 41, and the low acoustic impedance layer 42, respectively. Good too.
  • Audio wave device 2 Piezoelectric substrate 3: Support substrate 4: Acoustic multilayer film layer 41: High acoustic impedance layer 42: Low acoustic impedance layer 43: Bonding layer 5: IDT electrode 51: Comb-shaped electrode 511: Bus bar 512: Electrode finger 513: Dummy electrode finger 52: Reflector 101: Duplexer 102: Antenna terminal 103: Transmission terminal 104: Reception terminal 105: Transmission filter 106: Reception filter 111: Communication device 112: Antenna 113: RF-IC 114: Amplifier

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

Abstract

La présente invention concerne : un dispositif à ondes élastiques ayant d'excellentes caractéristiques de fréquence ; un filtre de dérivation comprenant le dispositif à ondes élastiques ; un dispositif de communication comprenant le dispositif à ondes élastiques ; et un procédé de fabrication du dispositif à ondes élastiques. Le dispositif à ondes élastiques a un substrat piézoélectrique, un substrat de support et un film multicouche acoustique situé entre le substrat piézoélectrique et le substrat de support. Le film multicouche acoustique est obtenu par la stratification en alternance d'une pluralité de couches à faible impédance acoustique et d'une pluralité de couches à impédance acoustique élevée. L'impédance acoustique des couches à impédance acoustique élevée est supérieure à l'impédance acoustique des couches à faible impédance acoustique. De plus, la rugosité moyenne arithmétique des couches à impédance acoustique élevée au niveau des interfaces de celles-ci sur le côté substrat de support se trouve dans une première plage prescrite ne comprenant pas 0 nm.
PCT/JP2023/008866 2022-03-09 2023-03-08 Dispositif à ondes élastiques, filtre de dérivation, dispositif de communication et procédé de fabrication de dispositif à ondes élastiques WO2023171715A1 (fr)

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JP2022036382 2022-03-09
JP2022-036382 2022-03-09

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005136761A (ja) * 2003-10-31 2005-05-26 Tdk Corp 薄膜音響共振子の製造方法
JP2006186833A (ja) * 2004-12-28 2006-07-13 Kyocera Kinseki Corp 圧電薄膜デバイス及びその製造方法
WO2009025118A1 (fr) * 2007-08-23 2009-02-26 Murata Manufacturing Co., Ltd. Résonateur piézoélectrique et procédé pour sa fabrication
WO2018154950A1 (fr) * 2017-02-21 2018-08-30 株式会社村田製作所 Dispositif à ondes élastiques, circuit frontal haute fréquence et dispositif de communication

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005136761A (ja) * 2003-10-31 2005-05-26 Tdk Corp 薄膜音響共振子の製造方法
JP2006186833A (ja) * 2004-12-28 2006-07-13 Kyocera Kinseki Corp 圧電薄膜デバイス及びその製造方法
WO2009025118A1 (fr) * 2007-08-23 2009-02-26 Murata Manufacturing Co., Ltd. Résonateur piézoélectrique et procédé pour sa fabrication
WO2018154950A1 (fr) * 2017-02-21 2018-08-30 株式会社村田製作所 Dispositif à ondes élastiques, circuit frontal haute fréquence et dispositif de communication

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