WO2022176738A1 - Elastic wave filter, method for manufacturing elastic wave filter, high-frequency module, and communication apparatus - Google Patents

Elastic wave filter, method for manufacturing elastic wave filter, high-frequency module, and communication apparatus Download PDF

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Publication number
WO2022176738A1
WO2022176738A1 PCT/JP2022/005133 JP2022005133W WO2022176738A1 WO 2022176738 A1 WO2022176738 A1 WO 2022176738A1 JP 2022005133 W JP2022005133 W JP 2022005133W WO 2022176738 A1 WO2022176738 A1 WO 2022176738A1
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WIPO (PCT)
Prior art keywords
main surface
substrate
piezoelectric substrate
wave filter
elastic wave
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PCT/JP2022/005133
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French (fr)
Japanese (ja)
Inventor
基嗣 津田
誠二 甲斐
央 山崎
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株式会社村田製作所
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Publication of WO2022176738A1 publication Critical patent/WO2022176738A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/02—Containers; Seals
    • 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

Definitions

  • the present invention relates to an elastic wave filter, an elastic wave filter manufacturing method, a high frequency module, and a communication device.
  • the present invention provides an acoustic wave filter provided with vias penetrating in the thickness direction in a piezoelectric substrate, a method for manufacturing the acoustic wave filter, a high frequency module including the acoustic wave filter, and the The present invention relates to a communication device having a high frequency module.
  • the electronic device (acoustic wave filter) described in Patent Document 1 includes a first substrate (piezoelectric substrate) having a bottom surface and a top surface. Electronic circuits and vias are formed in the first substrate. An electronic circuit is formed on the bottom surface of the first substrate. A via penetrates between the bottom surface and the top surface of the first substrate. A stopper layer (conductive member) is formed on the via on the bottom surface of the first substrate. An external electrode layer is formed on the via on the top surface of the first substrate. In this electronic device, a through hole is formed by laser processing in the portion of the first substrate where the via is to be formed.
  • Patent Document 1 since the through-hole is formed by laser processing from the top surface side (external electrode layer side) of the first substrate, the width of the through-hole goes to the bottom surface side (stopper layer side) of the first substrate. becomes thinner. Therefore, the width of the via also becomes narrower toward the bottom surface side (stopper layer side) of the first substrate. Therefore, the contact area between the via and the stopper layer (conductive member) is relatively small. As a result, the connection reliability between the via and the stopper layer is lowered, and if the electronic device is a filter, the filter characteristics are degraded.
  • An object of the present invention is to provide an elastic wave filter, an elastic wave filter manufacturing method, a high frequency module, and a communication device that can improve connection reliability between vias and conductive members and suppress deterioration of filter characteristics.
  • An acoustic wave filter of one aspect of the present invention includes a piezoelectric substrate, functional electrodes, conductive members, external terminals, and vias.
  • the piezoelectric substrate has a first main surface and a second main surface facing each other.
  • the piezoelectric substrate has piezoelectricity at least partially in the thickness direction.
  • the functional electrode is arranged on the first main surface of the piezoelectric substrate.
  • the conductive member is arranged on the first main surface of the piezoelectric substrate and connected to the functional electrode.
  • the external terminals are arranged on the second main surface of the piezoelectric substrate.
  • the via passes through the piezoelectric substrate in the thickness direction and connects the external terminal and the conductive member.
  • intersections between the via and the first main surface and the second main surface of the piezoelectric substrate are defined as first intersections and second intersections, respectively, and the via
  • a change point is a point where the inclination of the outer peripheral surface changes on the outer peripheral surface of the via, and the first intersection, the second intersection, and the change point are in the direction parallel to the second main surface of the piezoelectric substrate.
  • a first angle is an acute angle formed by a first line segment connecting the change point and the second intersection point and the second main surface on the same side, and a first angle is defined as a first angle connecting the change point and the first intersection
  • An acute angle formed by two line segments and an imaginary line passing through the change point and parallel to the second main surface of the piezoelectric substrate is defined as a second angle. The second angle is larger than the first angle.
  • a method for manufacturing an elastic wave filter according to one aspect of the present invention includes a first step, a second step, a third step, and a fourth step.
  • a substrate is prepared.
  • the substrate has a first main surface and a second main surface facing each other, and has piezoelectricity in at least a part of a thickness direction, and the functional electrode and the functional electrode are formed on the first main surface.
  • a connected conductive member is disposed.
  • a piezoelectric substrate having a through hole penetrating in the thickness direction of the substrate is formed.
  • a via is formed in the through hole of the piezoelectric substrate so as to be connected to the conductive member.
  • a plurality of external terminals including at least one external terminal connected to the via are formed on the main surface of the piezoelectric substrate.
  • a hole is formed from the second main surface of the substrate to a position between the first main surface and the second main surface of the substrate by laser processing. Then, by dry etching, the through hole is formed by penetrating between the bottom surface of the hole and the first main surface of the substrate.
  • a high-frequency module of one aspect of the present invention includes the elastic wave filter and a mounting substrate.
  • the mounting board mounts the elastic wave filter.
  • a communication device includes the high-frequency module and a signal processing circuit.
  • the signal processing circuit is connected to the high frequency module and processes a high frequency signal.
  • FIG. 1 is a block diagram of a high frequency module and communication device according to an embodiment.
  • FIG. 2 is a plan view of the elastic wave filter according to the embodiment.
  • FIG. 3 is a cross-sectional view taken along line X1-X1 in FIG. 4 is a partially enlarged view of FIG. 3.
  • FIG. 5A is an explanatory diagram illustrating an electrode forming step in the method for manufacturing an elastic wave filter.
  • FIG. 5B is an explanatory diagram illustrating a cover member forming step in the method for manufacturing an elastic wave filter.
  • FIG. 5C is an explanatory diagram illustrating a hole forming step in the method of manufacturing an elastic wave filter.
  • FIG. 5D is an explanatory diagram illustrating a through-hole forming step in the method for manufacturing an elastic wave filter.
  • FIG. 6A is an explanatory diagram illustrating a via formation step in the method of manufacturing an acoustic wave filter.
  • FIG. 6B is an explanatory diagram illustrating a bonding layer forming step in the method for manufacturing an elastic wave filter.
  • FIG. 6C is an explanatory diagram for explaining the external terminal forming step of the method of manufacturing the elastic wave filter.
  • FIG. 7 is a cross-sectional view of an acoustic wave filter according to Modification 1.
  • FIG. FIG. 8 is a cross-sectional view of an acoustic wave filter according to Modification 2.
  • the elastic wave filter 2 includes a piezoelectric substrate 41, an IDT electrode 42 (functional electrode), and a plurality of conductive auxiliary members (conductive members) 43. , a plurality of external terminals 45 , and a plurality of vias 44 .
  • the piezoelectric substrate 41 has a first major surface 41a and a second major surface 41b facing each other.
  • the piezoelectric substrate 41 has piezoelectricity at least partially in the thickness direction D1. In this embodiment, the piezoelectric substrate 41 has piezoelectricity in the entire thickness direction D1.
  • the IDT electrode 42 is arranged on the first main surface 41 a of the piezoelectric substrate 41 .
  • the conductive auxiliary member 43 is arranged on the first main surface 41 a of the piezoelectric substrate 41 and connected to the IDT electrode 42 .
  • a plurality of external terminals 45 are arranged on the second main surface 41 b of the piezoelectric substrate 41 .
  • a plurality of vias 44 pass through the piezoelectric substrate 41 in the thickness direction D ⁇ b>1 and connect at least one of the plurality of external terminals 45 and the conductive auxiliary member 43 . As shown in FIGS.
  • the intersection of the via 44 and the first principal surface 41a of the piezoelectric substrate 41 is defined as a first intersection point P1
  • the via 44 and the second principal surface 41b of the piezoelectric substrate 41 is defined as a second intersection point P2
  • a point where the inclination of the outer circumferential surface 44c of the via 44 changes is defined as a change point P3.
  • the first intersection point P1, the second intersection point P2, and the change point P3 are on the same side of the via 44 in the direction parallel to the second main surface 41b of the piezoelectric substrate 4 .
  • An acute angle formed by a first line segment H1 connecting the change point P3 and the second intersection point P2 and the second main surface 41b of the piezoelectric substrate 41 is defined as a first angle ⁇
  • an acute angle connecting the change point P3 and the first intersection point P1 is defined as a first angle ⁇
  • the acute angle formed by the two line segments H2 and the virtual line L1 is defined as a second angle ⁇ .
  • the virtual line L1 is parallel to the second main surface 41b of the piezoelectric substrate 41 through the change point P3.
  • the second angle ⁇ is greater than the first angle ⁇ .
  • the second angle ⁇ is larger than the first angle ⁇ .
  • the width W1 of the via 44 at the first main surface 41a of can be increased.
  • the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large.
  • connection reliability between the via 44 and the conductive auxiliary member 43 can be improved.
  • the electrical resistance and inductance at the contact portion between the via 44 and the conductive auxiliary member 43 can be reduced, thereby suppressing deterioration of filter characteristics.
  • the elastic wave filter 2 according to the present embodiment, the method for manufacturing the elastic wave filter 2, the high frequency module 1 including the elastic wave filter 2, and the communication device 100 including the high frequency module 1 will be described with reference to FIG. A detailed description will be given with reference to FIG. 6C.
  • the communication device 100 is, for example, a mobile terminal (eg, smart phone), but is not limited to this, and may be, for example, a wearable terminal (eg, smart watch).
  • the high-frequency module 1 is a module compatible with, for example, the 4G (fourth generation mobile communication) standard and the 5G (fifth generation mobile communication) standard.
  • the 4G standard is, for example, the 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) standard.
  • the 5G standard is, for example, 5G NR (New Radio).
  • the radio frequency module 1 is a module capable of supporting carrier aggregation and dual connectivity.
  • the communication device 100 includes a signal processing circuit 20 and one or more (one in the illustrated example) antennas 40 in addition to the high frequency module 1 .
  • the high-frequency module 1 is configured to amplify a received signal (high-frequency signal) received by the antenna 40 and output it to the signal processing circuit 20 .
  • the high frequency module 1 is also configured to amplify a transmission signal (high frequency signal) from the signal processing circuit 20 and output the amplified signal to the antenna 40 .
  • the high frequency module 1 is controlled by a signal processing circuit 20, for example.
  • the signal processing circuit 20 is connected to the high frequency module 1 and configured to process the received signal received from the high frequency module 1 . Further, the signal processing circuit 20 is configured to process the transmission signal to be output to the high frequency module 1 .
  • the signal processing circuit 20 includes an RF signal processing circuit 21 and a baseband signal processing circuit 22 .
  • the RF signal processing circuit 21 is, for example, an RFIC (Radio Frequency Integrated Circuit), and performs signal processing on high-frequency signals (received signals and transmitted signals).
  • the RF signal processing circuit 21 for example, performs signal processing such as down-conversion on the received signal received from the high-frequency module 1 and outputs the processed signal to the baseband signal processing circuit 22 . Further, the RF signal processing circuit 21 performs signal processing such as up-conversion on the transmission signal output from the baseband signal processing circuit 22 and outputs the signal to the high frequency module 1 .
  • the baseband signal processing circuit 22 is, for example, a BBIC (Baseband Integrated Circuit).
  • the baseband signal processing circuit 22 outputs the reception signal received from the RF signal processing circuit 21 to the outside. This output signal (received signal) can be used, for example, as an image signal for image display, or as an audio signal for communication.
  • the baseband signal processing circuit 22 also generates a transmission signal from an externally input baseband signal (for example, an audio signal and an image signal) and outputs the generated transmission signal to the RF signal processing circuit 21 .
  • the high-frequency module 1 transmits high-frequency signals (for example, received signals and transmitted signals) between the signal processing circuit 20 and the antenna 40 .
  • the high frequency module 1 includes, for example, a switch 3, a reception filter 4, a transmission filter 5, matching circuits 6 and 7, a low noise amplifier 8, and a power amplifier 9 as electronic components.
  • the reception filter 4 and the transmission filter 5 are examples of the elastic wave filter 2 of this embodiment.
  • the high-frequency module 1 also includes a plurality of (for example, three) external connection terminals 10 .
  • the high-frequency module 1 also includes a plurality (eg, three) of signal paths R1 to R3.
  • the high-frequency module 1 also includes a mounting board 11 on which the electronic components and the external connection terminals 10 are mounted, as shown in FIG.
  • the mounting substrate 11 has a first major surface 11a and a second major surface (not shown) facing each other.
  • the electronic components and external connection terminals 10 described above are mounted on the first main surface 11a or the second main surface of the mounting board 11 .
  • the plurality of external connection terminals 10 include an antenna terminal 10A, a signal output terminal 10B, and a signal input terminal 10C.
  • the antenna terminal 10A is a terminal to which the antenna 40 is connected.
  • the signal output terminal 10B is a terminal for outputting the received signal processed by the high frequency module 1 to the signal processing circuit 20, and is connected to the signal processing circuit 20.
  • the signal input terminal 10 ⁇ /b>C is a terminal for receiving a transmission signal from the signal processing circuit 20 and is connected to the signal processing circuit 20 .
  • the signal paths R1 to R3 constitute a signal path R0 connecting a plurality of external connection terminals 10 for inputting or outputting signals (received signals or transmitted signals). That is, signal paths R1-R3 are part of signal path R0.
  • a signal path R0 is a signal path through which a signal passing through the antenna terminal 10A flows.
  • a signal path R1 is a signal path that connects the antenna terminal 10A and the common terminal 3a of the switch 3 .
  • a signal path R2 is a signal path that connects the selection terminal 3b of the switch 3 and the signal output terminal 10B.
  • a reception filter 4, a matching circuit 6, and a low noise amplifier 8 are provided in the signal path R2.
  • a signal path R3 is a signal path that connects the selection terminal 3c of the switch 3 and the signal input terminal 10C.
  • a transmission filter 5, a matching circuit 7, and a power amplifier 9 are provided in the signal path R3.
  • the switch 3 selects a signal path used for receiving a received signal or transmitting a transmitted signal from among the plurality of signal paths R1 and R2, and connects the selected signal path to the antenna terminal 10A. is connected to the signal path R1 connected to the .
  • the switch 3 is, for example, a switch IC (Integrated Circuit).
  • the switch 3 has one or more (for example, one) common terminal 3a and two or more (two in the illustrated example) selection terminals 3b and 3c.
  • the common terminal 3a is connected to the antenna terminal 10A via the signal path R1.
  • the selection terminal 3b is connected to the input of the reception filter 4 via the signal path R2, and the selection terminal 3c is connected to the output of the transmission filter 5 via the signal path R3.
  • the switch 3 selects one selection terminal connected to the common terminal 3a from among the plurality of selection terminals 3b and 3c.
  • the receiving filter 4 is provided on the signal path R2 and passes the signal flowing through the signal path R2.
  • the receive filter 4 has a first passband for passing signals in the first communication band.
  • the receive filter 4 has an input section (not shown) and an output section (not shown).
  • the input portion of the reception filter 4 is connected to the selection terminal 3b of the switch, and the output portion of the reception filter 4 is connected to the matching circuit 6.
  • FIG. The reception filter 4 limits the reception signal input to the input section to a signal in the first passband and outputs the signal from the output section.
  • the transmission filter 5 is provided on the signal route R3 and passes the signal flowing through the signal route R3.
  • the transmit filter 5 has a second passband that passes signals in the second communication band.
  • the transmit filter 5 has an input (not shown) and an output (not shown).
  • An input portion of the transmission filter 5 is connected to the matching circuit 7 , and an output portion of the transmission filter 5 is connected to the selection terminal 3 c of the switch 3 .
  • the transmission filter 5 limits the transmission signal input to the input section of the transmission filter 5 to a signal in the second passband and outputs the signal from the output section of the transmission filter 5 .
  • the reception filter 4 and the transmission filter 5 are each composed of an acoustic wave filter 2.
  • the acoustic wave filter 2 is, for example, a surface acoustic wave (SAW) filter that utilizes surface acoustic waves.
  • the elastic wave filter 2 has a plurality of elastic wave resonators. Each elastic wave resonator has a piezoelectric substrate 41 and an IDT electrode 42 (functional electrode) formed on the piezoelectric substrate 41 .
  • a plurality of acoustic wave resonators form a ladder-type circuit having series arm resonators and parallel arm resonators.
  • the elastic wave filter 2 is not limited to a SAW filter, and may be, for example, a BAW (Bulk Acoustic Wave) filter other than a SAW filter.
  • the low noise amplifier 8 is provided in the signal path R2.
  • the low noise amplifier 8 has an input (not shown) and an output (not shown).
  • the input section is connected to the matching circuit 6, and the output section is connected to the signal output terminal 10B.
  • the low noise amplifier 8 amplifies the received signal input to the input section and outputs the amplified signal from the output section.
  • a power amplifier 9 is provided on the signal path R3.
  • the power amplifier 9 has an input (not shown) and an output (not shown).
  • the input section is connected to the signal input terminal 10C.
  • the output section is connected to the matching circuit 7 .
  • the power amplifier 9 amplifies the transmission signal input to the input section and outputs it from the output section.
  • the matching circuit 6 is provided on the signal path R2.
  • the matching circuit 6 is a circuit for impedance matching between the reception filter 4 and the low noise amplifier 8 and is connected between the reception filter 4 and the low noise amplifier 8 .
  • the matching circuit 7 is provided on the signal path R3.
  • the matching circuit 7 is a circuit for impedance matching between the transmission filter 5 and the power amplifier 9 and is connected between the transmission filter 5 and the power amplifier 9 .
  • the common terminal 3a of the switch 3 is connected to the selection terminal 3b. This connects the signal path R1 and the signal path R2.
  • the reception signal flows through the signal paths R1 and R2.
  • the received signal passes through the receive filter 4, the matching circuit 6 and the low noise amplifier 8 in order.
  • the received signal is then output to the signal processing circuit 20 from the signal output terminal 10B.
  • the common terminal 3a of the switch 3 is connected to the selection terminal 3c. This connects the signal path R1 and the signal path R3.
  • the receiving filter 4 and the transmitting filter 5 basically have the same structure as each other, only the structure of the receiving filter 4 will be described below. , the description of the structure of the transmission filter 5 is omitted.
  • the reception filter 4 is composed of the acoustic wave filter 2 as described above. As shown in FIGS.
  • the acoustic wave filter 2 includes a piezoelectric substrate 41, a plurality of (three in the illustrated example) IDT electrodes 42, and a plurality of (four in the illustrated example) conductive auxiliary members 43 ( conductive member), a plurality of (three in the illustrated example) vias 44 , a plurality of external terminals 45 , a plurality of bonding layers 46 , a peripheral wall 47 , and a cover member 48 .
  • the piezoelectric substrate 41 is a substrate on which components constituting the acoustic wave filter 2 are mounted, and has, for example, a rectangular plate shape.
  • the piezoelectric substrate 41 is a substrate having piezoelectricity at least partially in the thickness direction D1 of the piezoelectric substrate 41 .
  • the piezoelectric substrate 41 is a piezoelectric substrate 49 having piezoelectricity throughout the thickness direction D1.
  • the piezoelectric substrate 49 is made of, for example, lithium tantalate (LiTaO 3 ) or lithium niobate (LiNbO 3 ).
  • the piezoelectric substrate 41 has a first main surface 41a and a second main surface 41b facing each other in the thickness direction D1.
  • the IDT electrode 42 is provided in the form of a film on the first main surface 41a of the piezoelectric substrate 41 .
  • the IDT electrode 42 is formed by laminating aluminum (Al) and titanium (Ti) in order from the upper layer side, for example.
  • the IDT electrode 42 has a pair of comb electrodes 422 .
  • a pair of comb-shaped electrodes 422 each has a plurality of electrode fingers 423 and bus bars 424 .
  • Each of the plurality of electrode fingers 423 has, for example, a strip shape when viewed from the thickness direction D1 of the piezoelectric substrate 41 in plan view.
  • the plurality of electrode fingers 423 are arranged so as to be spaced apart and parallel to each other in the direction orthogonal to their longitudinal direction.
  • each of the plurality of electrode fingers 423 is connected to bus bar 424 .
  • the bus bar 424 is wiring for supplying a voltage to the plurality of electrode fingers 423, and is strip-shaped, for example.
  • the bus bar 424 is connected to one ends of the electrode fingers 423 .
  • the IDT electrodes 42 are arranged such that the plurality of electrode fingers 423 of the pair of comb-shaped electrodes 422 are engaged with each other.
  • Each of the plurality of IDT electrodes 42 constitutes an elastic wave resonator together with the piezoelectric substrate 41 .
  • Each of the plurality of conductive auxiliary members 43 is a member that connects the IDT electrodes 42 together or a member that connects the IDT electrodes 42 and the vias 44 . Further, each conductive auxiliary member 43 is a member that functions as a stopper layer when the through hole 70 (see FIG. 5D) for forming the via 44 is formed in the piezoelectric substrate 41 by dry etching and laser processing. The conductive auxiliary member 43 is formed thicker than the IDT electrode 42 in order to reduce electrical resistance and inductance. The conductive auxiliary member 43 is formed by laminating a plurality of metal layers.
  • the conductive auxiliary member 43 is formed by laminating aluminum (Al), titanium (Ti), platinum (Pt), and titanium in this order from the upper layer side.
  • the conductive auxiliary member 43 may be formed by laminating aluminum and titanium in order from the upper layer side, may be formed by laminating aluminum and chromium (Cr) in order from the upper layer side, or may be formed by laminating gold (Au ) and titanium may be laminated.
  • the conductive auxiliary member 43 may be made of a single metal (for example, gold (Au)).
  • the external terminals 45 are provided on the second main surface 41 b of the piezoelectric substrate 41 .
  • the external terminal 45 is a terminal for electrically connecting the elastic wave filter 2 to an external substrate (for example, the mounting substrate 11 of the high frequency module 1).
  • the external terminal 45 is connected to the via 44 through the bonding layer 46 .
  • the external terminals 45 are, for example, solder terminals made of solder.
  • the bonding layer 46 is provided between the external terminal 45 and the via 44 and is a member that bonds the external terminal 45 and the via 44 .
  • the bonding layer 46 is, for example, a gold-nickel alloy (AuNi). Since the bonding layer 46 is not an essential component in this embodiment, it may be omitted. In this case, the external terminal 45 is directly connected to the via 44 .
  • the via 44 is a member that penetrates through the piezoelectric substrate 41 in the thickness direction D ⁇ b>1 and electrically connects the conductive auxiliary member 43 and at least one of the plurality of external terminals 45 .
  • the via 44 is connected to the external terminal 45 via the bonding layer 46 as described above.
  • the via 44 is made of copper (Cu) or a copper alloy, for example.
  • the peripheral wall 47 is arranged between the piezoelectric substrate 41 and the cover member 48 to secure an accommodation space SP1 for accommodating the IDT electrode 42 and the conductive auxiliary member 43 between the piezoelectric substrate 41 and the cover member 48. It is a member (for example, a spacer) that The peripheral wall 47 has a frame shape, for example, and is arranged on the first main surface 41 a of the piezoelectric substrate 41 so as to surround the IDT electrode 42 and the conductive auxiliary member 43 .
  • the peripheral wall 47 is made of, for example, polyimide, epoxy resin, or silicon (Si).
  • the cover member 48 is a member that covers the opening of the peripheral wall 47 on the side opposite to the first main surface 41a side.
  • the cover member 48 is provided at the end of the peripheral wall 47 opposite to the first principal surface 41a.
  • the cover member 48 has, for example, a flat plate shape.
  • the cover member 48 is made of polyimide, epoxy resin, or silicon (Si), for example.
  • FIG. 4 is a partially enlarged view of FIG. 3, and is a cross-sectional view when the piezoelectric substrate 41 is cut along a predetermined cross section.
  • the predetermined cross section is, for example, a cross section perpendicular to the second main surface 41b of the piezoelectric substrate 41 and including the via 44 (more specifically, the center of the top surface of the via 44 (the surface on the first main surface 41a side)). is.
  • the via 44 has a columnar shape whose width gradually decreases from the second main surface 41b side (that is, the external terminal 45 side) of the piezoelectric substrate 41 toward the first main surface 41a side (that is, the conductive auxiliary member 43 side).
  • the via 44 has a first columnar portion 441 and a second columnar portion 442 .
  • the first columnar portion 441 is a columnar portion having a height T1.
  • the height T1 is the height from the second main surface 41b of the piezoelectric substrate 41 to the middle of the piezoelectric substrate 41 in the thickness direction D1.
  • the height T1 is the height from the second principal surface 41b of the piezoelectric substrate 41 to a position between the first principal surface 41a and the second principal surface 41b.
  • the height T1 may be, for example, more than half the thickness of the piezoelectric substrate 41, preferably more than two-thirds the thickness of the piezoelectric substrate 41, More preferably, it may be greater than three quarters of the thickness of the piezoelectric substrate 41 .
  • the first columnar portion 441 has, for example, a truncated cone shape, and the diameter of the first columnar portion 441 gradually decreases from the second main surface 41b side of the piezoelectric substrate 41 toward the first main surface 41a side. Therefore, the outer peripheral surface 441a of the first columnar portion 441 extends from the bottom surface 441b (the surface on the second main surface 41b side, the first surface) of the first columnar portion 441 to the top surface 441c (the surface on the first main surface 41a side, the first surface). 2 surface), and is inclined inwardly of the first column portion 441 .
  • the second columnar portion 442 is a columnar portion having a height T2.
  • a height T2 is the height from the top surface of the first columnar portion 441 to the first main surface 41a of the piezoelectric substrate 41 .
  • the entire bottom surface 442 b (the surface on the second main surface 41 b side) of the second columnar portion 442 overlaps the entire top surface 441 c of the first columnar portion 441 .
  • the second columnar portion 442 has, for example, a truncated cone shape, and the diameter of the second columnar portion 442 gradually decreases from the second main surface 41b side of the piezoelectric substrate 41 toward the first main surface 41a side.
  • the outer peripheral surface 442a of the second columnar portion 442 extends from the bottom surface 442b (the surface on the side of the second main surface 41b, the first surface) of the second columnar portion 442 to the top surface 442c (the surface on the side of the first main surface 41a, the surface on the side of the first main surface 41a). 2), and is inclined inwardly of the second column portion 442 .
  • the inclination of the outer peripheral surface 442 a of the second columnar portion 442 is steeper than the inclination of the outer peripheral surface 441 a of the first columnar portion 441 .
  • the vias 44 are formed along the left and right side edges. 44a and 44b.
  • the side edges 44a and 44b are the crossing portions of the outer peripheral surface 44c of the via 44 and the cross section described above.
  • the intersection of the side 44a of the via 44 and the first main surface 41a of the piezoelectric substrate 41 is defined as a first intersection P1
  • the intersection of the side 44a of the via 44 and the second main surface 41b of the piezoelectric substrate 41 is defined as a second intersection.
  • the point at which the slope of the side 44a of the via 44 changes is the point of change P3.
  • the change point P3 is a point at which the inclination of the outer peripheral surface 44c of the via 44 changes in the cross-sectional view of the cross section.
  • the inclination of the outer peripheral surface 44c in the cross-sectional view of the cross section is the inclination of the portion that intersects with the outer peripheral surface 44c of the via 44 in the cross section.
  • the first intersection point P1, the second intersection point P2, and the change point P3 are located on the same side of the via 44 in the direction parallel to the second main surface 41b of the piezoelectric substrate 41 (for example, in FIG. on the right).
  • a line segment connecting the change point P3 and the second intersection point P2 is defined as a first line segment H1, and a line segment connecting the change point P3 and the first intersection point P1 is defined as a second line segment H2.
  • the acute angle formed by the first line segment H1 and the second main surface 41b of the piezoelectric substrate 41 in the above cross-sectional view is defined as a first angle ⁇
  • the second line segment H2 and the virtual line L1 in the above cross-sectional view are formed.
  • the acute angle to form be the second angle ⁇ .
  • the virtual line L1 is a line parallel to the second main surface 41b passing through the point of change P3.
  • the second angle ⁇ is larger than the first angle ⁇ .
  • the inclination of the outer peripheral surface 442 a of the second pillar 442 is steeper than the inclination of the outer peripheral surface 442 a of the first pillar 441 .
  • the top surface of the second columnar portion 442 in the cross-sectional view described above is larger than the case where the second angle ⁇ is the same as the first angle ⁇ .
  • the width W1 of 442c (that is, the width of via 44 on first main surface 41a) can be increased.
  • the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large.
  • connection reliability between the via 44 and the conductive auxiliary member 43 can be improved.
  • the electrical resistance and inductance at the contact portion between the via 44 and the conductive auxiliary member 43 can be reduced, thereby suppressing deterioration of filter characteristics.
  • the IDT electrode 42 and the conductive auxiliary member 43 are formed on the first main surface 410a of the substrate 410 used as the piezoelectric substrate 41.
  • a metal film to be used as the IDT electrode 42 is formed on the first main surface 410a of the substrate 410 by vapor deposition or sputtering, for example.
  • the metal film is, for example, a film in which aluminum (Al) and titanium (Ti) are laminated in this order from the upper layer side.
  • the IDT electrode 42 is formed by forming the formed metal film into a predetermined shape by a photolithography process.
  • the conductive auxiliary member 43 is formed by the same manufacturing procedure as that of the IDT electrode 42 .
  • the conductive auxiliary member 43 is a film in which, for example, aluminum, titanium, platinum (Pt), and titanium are laminated in this order from the upper layer side.
  • the conductive auxiliary member 43 is connected to the IDT electrode 42 .
  • the bottom layer (titanium layer) of the conductive auxiliary member 43 functions as a stopper layer when a hole is made in the substrate 410 by laser processing and dry etching, as will be described later.
  • the substrate 410 on which the IDT electrodes 42 and the conductive auxiliary members 43 connected to the IDT electrodes 42 are arranged on the first main surface 410a is prepared.
  • the peripheral wall 47 and the cover member 48 are formed on the first main surface 410a of the substrate 410. More specifically, first, a layer (for example, a polyimide layer) used as the peripheral wall 47 is formed over the entire first main surface 410a of the substrate 410, and the formed layer is formed into a predetermined shape by a photolithography process. Thereby, the peripheral wall 47 is formed. Then, a member (for example, an epoxy resin sheet) used as the cover member 48 is placed on the top portion of the peripheral wall 47 (on the side opposite to the first main surface 41a) so as to close the opening on the top portion side of the peripheral wall 47 (on the side opposite to the first main surface 41a). the opposite end). Thereby, the cover member 48 is provided on the top of the peripheral wall 47 .
  • a layer for example, a polyimide layer used as the peripheral wall 47 is formed over the entire first main surface 410a of the substrate 410, and the formed layer is formed into a predetermined shape by a photolithography process. Thereby,
  • through holes 70 for providing vias 44 are formed in the substrate 410 . More specifically, first, as shown in FIG. 5C, a hole 60 having a predetermined depth K1 is formed at a predetermined position in the second main surface 410b of the substrate 410 by laser processing.
  • the depth K1 of the hole portion 60 is the depth from the second main surface 410b of the substrate 410 to the middle of the substrate 410 in the thickness direction D1.
  • depth K1 of hole 60 is the depth from second main surface 410b of substrate 410 to a position between first main surface 410a and second main surface 410b of substrate 410 .
  • the depth K1 of the hole 60 is, for example, half or more the thickness of the substrate 410 .
  • the depth K1 is the same height as the height T1 of the first columnar portion 441 of the via 44 .
  • the laser processing is performed using the auxiliary conductive member 43 as a stopper layer. It is desirable to make the interval as small as possible. This makes it possible to dig the hole 60 as deeply as possible and prevent damage to the conductive auxiliary member 43 due to laser heat.
  • the output of the laser is controlled so as to weaken as the hole 60 is dug. Therefore, the diameter (width) W2 of the hole portion 60 decreases from the second main surface 410b side to the first main surface 410a side. That is, the inner peripheral surface 60b of the hole portion 60 is inclined inwardly of the hole portion 60 from the second main surface 410b side toward the first main surface 410a.
  • a through hole 61 is formed through the bottom surface 60a of the hole 60 to the first main surface 410a of the substrate 410 by dry etching. That is, dry etching is used to penetrate between the bottom surface 60a of the hole 60 and the first main surface 41a. Thereby, a through hole 70 penetrating through the piezoelectric substrate 41 is formed.
  • the through hole 70 is composed of the hole portion 60 and the through hole 61 .
  • the auxiliary conductive member 43 is exposed from the opening of the through hole 70 in the first main surface 41a.
  • the entire surface of the substrate 410 on the second main surface 410b side (particularly the surface portions Q1 and Q2 in FIG. It penetrates between the first major surface 410 a of the substrate 410 .
  • Surface portion Q1 is a portion including second main surface 410b of substrate 410
  • surface portion Q2 is a portion between bottom surface 60a of hole 60 and first main surface 41a of substrate 410.
  • the inner peripheral surface 60b of the hole 60 is also etched to some extent in addition to the surface portions Q1 and Q2.
  • the inner peripheral surface 60b of the hole 60 may be slightly roughened by laser processing, or may have burnt residue due to laser processing, but the inner peripheral surface 60b of the hole 60 is processed smoothly by this dry etching. And the burnt residue is scraped off. That is, in this manufacturing method, the manufacturing process (dry etching) for penetrating the bottom surface 60a of the hole 60 also serves as the manufacturing process for smoothing the inner peripheral surface 60b of the hole 60.
  • this dry etching is performed for a predetermined time (sufficient time) until the diameter W3 of the through hole 61 at the first main surface 41a reaches a predetermined width.
  • the inner peripheral surface 61b of the through-hole 61 is inclined inwardly from the second main surface 41b toward the first main surface 41a.
  • the inclination is steeper than the inclination of the inner peripheral surface 60 b of the hole portion 60 .
  • the inclination of the inner peripheral surface 70 b of the through hole 70 changes at the boundary between the inner peripheral surface 60 b of the hole portion 60 and the inner peripheral surface 61 b of the through hole 61 . This boundary corresponds to the change point P3.
  • metal for example, copper
  • vias 44 made of copper, for example, are formed.
  • the inside of the through-hole 70 is the space inside the through-hole 70 and the space between the open surfaces on both sides of the through-hole 70 .
  • the entire top surface 442c of the via 44 (that is, the top surface of the second columnar portion 442) is connected to the conductive auxiliary member 43.
  • the shape of the via 44 is the same as the shape of the inside of the through hole 70 .
  • the inclination of the outer peripheral surface 44c of the via 44 changes at the boundary between the hole portion 60 and the through hole 61 (change point P3). That is, in the cross-sectional view described above, the slope of the line segment H2 corresponding to the through hole 61 is steeper than the slope of the line segment H1 corresponding to the hole 60 on the side 44a of the via 44 .
  • a bonding layer 46 is formed from a metal (for example, a gold-nickel alloy) so as to be connected to the bottom surface of the via 44 on the second main surface 41b of the piezoelectric substrate 41 .
  • a bonding layer 46 made of, for example, a gold-nickel alloy is formed.
  • external terminals 45 for example, solder bumps
  • the piezoelectric substrate 41 is entirely made of lithium tantalate or lithium niobate in the thickness direction D1.
  • the through hole 70 is formed in the piezoelectric substrate 41 made of such a material only by laser processing, the through hole 70 can be formed in a relatively short time. 43 may be damaged.
  • the through-holes 70 are formed only by dry etching in the piezoelectric substrate 41 made of the above materials, the possibility of damaging the electrically conductive auxiliary member 43 as a stopper layer is low, but the processing is difficult and the through-holes can be formed. It takes time to form 70.
  • the through holes 70 are formed in the piezoelectric substrate 41 using both laser processing and dry etching. That is, the holes 60 are formed in the piezoelectric substrate 41 to a certain depth K1 (for example, to the vicinity of the conductive auxiliary member 43) in a relatively short period of time by laser processing, and dry etching is performed thereafter. to form the through hole 61 so as not to damage the conductive auxiliary member 43 . As a result, the through hole 70 is formed in a relatively short time so as not to damage the conductive auxiliary member 43 .
  • both laser processing and dry etching are used as described above, it is possible to prevent the laser during laser processing from directly hitting the electrical auxiliary member 43 . That is, if the laser hits the auxiliary conductive member 43 , the auxiliary conductive member 43 may be deformed by the heat of the laser, and peeling may occur between the auxiliary conductive member 43 and the piezoelectric substrate 41 .
  • both laser processing and dry edging are used as described above, it is possible to prevent the laser from directly hitting the conductive auxiliary member 43 . As a result, the peeling caused by the heat of the laser can be suppressed.
  • the acoustic wave filter 2 includes the piezoelectric substrate 41, the IDT electrodes 42 (functional electrodes), the conductive auxiliary members 43, the external terminals 45, and the vias 44. .
  • the piezoelectric substrate 41 has a first major surface 41a and a second major surface 41b facing each other.
  • the piezoelectric substrate 41 has piezoelectricity at least partially in the thickness direction D1.
  • the IDT electrode 42 is arranged on the first main surface 41 a of the piezoelectric substrate 41 .
  • the conductive auxiliary member 43 (auxiliary member) is arranged on the first main surface 41 a of the piezoelectric substrate 41 and connected to the IDT electrode 42 .
  • the external terminals 45 are arranged on the second main surface 41 b of the piezoelectric substrate 41 .
  • the via 44 penetrates the piezoelectric substrate 41 in the thickness direction D ⁇ b>1 and connects the external terminal 45 and the conductive auxiliary member 43 .
  • intersections between the vias 44 and the first main surface 41a and the second main surface 41b of the piezoelectric substrate 41 are designated as a first intersection point P1 and a second main surface 41b, respectively.
  • the point where the inclination of the outer peripheral surface 44c changes on the outer peripheral surface 44c of the via 44 is a change point P3.
  • An acute angle formed by a first line segment H1 connecting the change point P3 and the second intersection point P2 and the second main surface 41b of the piezoelectric substrate 41 is defined as a first angle ⁇
  • an acute angle connecting the change point P3 and the first intersection point P1 is defined as a first angle ⁇
  • the acute angle formed by the two line segments H2 and the virtual line L1 is defined as a second angle ⁇ .
  • the virtual line L1 is parallel to the second main surface 41b of the piezoelectric substrate 41 through the change point P3.
  • the second angle ⁇ is greater than the first angle ⁇ .
  • the second angle ⁇ is larger than the first angle ⁇ .
  • the width W1 of the via 44 at the first main surface 41a of can be increased.
  • the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large.
  • connection reliability between the via 44 and the conductive auxiliary member 43 can be improved.
  • the electrical resistance and inductance at the contact portion between the via 44 and the conductive auxiliary member 43 can be reduced, thereby suppressing deterioration of filter characteristics.
  • the piezoelectric substrate 41 has piezoelectricity in the entire thickness direction D1, but in this modified example, the piezoelectric substrate 41 has piezoelectricity in part in the thickness direction D1. Illustrate the case. As shown in FIG. 7 , in this modification, the piezoelectric substrate 41 includes a piezoelectric layer 411 and a support substrate 412 .
  • the support substrate 412 is a substrate that supports the piezoelectric layer 411, and is, for example, a silicon substrate made of silicon (Si).
  • the piezoelectric layer 411 is a portion having piezoelectric properties, and is made of, for example, lithium tantalate (LiTaO 3 ) or lithium niobate (LiNbO 3 ).
  • the thickness d1 of the piezoelectric layer 411 is smaller than the thickness d2 of the support substrate 412. As shown in FIG. A ratio of the thickness d1 of the piezoelectric layer 411 to the thickness d2 of the support substrate 412 is, for example, 1:9.
  • the piezoelectric layer 411 is formed over one side of the support substrate 412 .
  • An IDT electrode 42 , a conductive auxiliary member 43 , a peripheral wall 47 and a cover member 48 are provided on the main surface of the piezoelectric layer 411 opposite to the support substrate 412 side.
  • the acoustic velocity of the bulk wave propagating through the support substrate 412 is higher than the acoustic velocity of the elastic wave propagating through the piezoelectric layer 411 .
  • the bulk wave propagating through the support substrate 412 is the bulk wave having the lowest velocity among the plurality of bulk waves propagating through the support substrate 412 .
  • the thickness d2 of the support substrate 412 is preferably 10 ⁇ ( ⁇ : wavelength of elastic wave determined by electrode finger pitch) ⁇ m or more and 180 ⁇ m or less, for example, 120 ⁇ m.
  • the plane orientation of the first main surface 412a of the support substrate 412 is, for example, the (100) plane.
  • the plane orientation may be the (110) plane, the (111) plane, or the like.
  • the propagation direction of elastic waves can be set without being restricted by the plane direction of the first main surface 412 a of the support substrate 412 .
  • the support substrate 412 is not limited to a silicon substrate.
  • Support substrate 412 is made from silicon, aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, sapphire, lithium tantalate, lithium niobate, quartz, alumina, zirconia, cordierite, mullite, steatite, forsterite, magnesia, and diamond. It is sufficient that at least one material selected from the group consisting of is included.
  • the piezoelectric layer 411 has a first main surface 411a and a second main surface 411b facing each other.
  • the first main surface 411a and the second main surface 411b face each other in the thickness direction D1 of the piezoelectric substrate 41 .
  • the piezoelectric layer 411 is made of, for example, a ⁇ ° Y-cut X-propagating LiTaO 3 piezoelectric single crystal.
  • the ⁇ ° Y-cut X-propagating LiTaO3 piezoelectric single crystal has three crystal axes of the LiTaO3 piezoelectric single crystal as the X axis, the Y axis, and the Z axis. It is a LiTaO 3 single crystal cut along a plane normal to the axis rotated by ⁇ °, and a single crystal in which a surface acoustic wave propagates in the X-axis direction.
  • ⁇ and ⁇ 180 ⁇ n are synonymous (crystallographically equivalent).
  • n is a natural number.
  • the piezoelectric layer 411 is not limited to the ⁇ ° Y-cut X-propagating LiTaO 3 piezoelectric single crystal, and may be, for example, ⁇ ° Y-cut X-propagating LiTaO 3 piezoelectric ceramics.
  • the thickness d1 of the piezoelectric layer 411 is, for example, 3.5 ⁇ or less, where ⁇ is the wavelength of the elastic wave determined by the electrode finger pitch of the IDT electrode 42 .
  • ⁇ is the wavelength of the elastic wave determined by the electrode finger pitch of the IDT electrode 42 .
  • the Q Quality factor
  • the TCF Temporal Coefficient of Frequency
  • the elastic wave filter 2 as modes of elastic waves propagating through the piezoelectric layer 411, there are longitudinal waves, SH waves, SV waves, or a mode combining these.
  • a mode having SH waves as a main component is used as a main mode.
  • a higher-order mode is a spurious mode generated on the higher frequency side than the main mode of the elastic wave propagating through the piezoelectric layer 411 .
  • the main mode is a mode having an SH wave as a main component
  • parameters of the piezoelectric layer 411 material, Euler angle, thickness, etc.
  • parameters of the IDT electrode 42 material, thickness, electrode finger pitch, etc.
  • the displacement distribution is analyzed by the finite element method, and the distortion can be analyzed.
  • the Euler angles of the piezoelectric layer 411 can be obtained by analysis.
  • the material of the piezoelectric layer 411 is not limited to lithium tantalate ( LiTaO 3 ). PZT).
  • the piezoelectric layer 411 is made of, for example, a Y-cut X-propagating LiNbO 3 piezoelectric single crystal or piezoelectric ceramics, the acoustic wave filter 2 can utilize the SH mode with a higher coupling coefficient.
  • a through hole 70 is provided in the piezoelectric substrate 41 as in the above embodiment.
  • a change point P3 of the through hole 70 exists within the support substrate 412 . That is, in this modification, the hole 60 having a depth from the second main surface 41b of the piezoelectric substrate 41 to the middle of the support substrate 412 in the thickness direction is formed by laser processing. Then, by dry etching, the through-hole 61 is formed by penetrating the remaining portion of the support substrate 412 in the thickness direction and the piezoelectric layer 411 .
  • the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large, as in the above-described embodiment.
  • a low acoustic velocity film 413 and a high acoustic velocity film 414 may be provided between the piezoelectric layer 411 and the support substrate 412 .
  • the low sound velocity film 413 is made of silicon oxide, for example.
  • the high acoustic velocity film 414 is made of silicon nitride, for example. In this case, a high acoustic velocity film 414 is laminated on a support substrate 412 , a low acoustic velocity film 413 is laminated on the high acoustic velocity film 414 , and a piezoelectric layer 411 is laminated on the low acoustic velocity film 413 .
  • the piezoelectric substrate 41 comprises a piezoelectric layer 411 , a support substrate 412 , a low acoustic velocity film 413 and a high acoustic velocity film 414 .
  • the change point P3 of the through-hole 70 exists within the support substrate 412 .
  • the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large, as in the above-described embodiment.
  • the low sound velocity film 413 is a film in which the sound velocity of the bulk wave propagating through the low sound velocity film 413 is lower than the sound velocity of the bulk wave propagating through the piezoelectric layer 411 .
  • the low sound velocity film 413 is provided between the support substrate 412 and the piezoelectric layer 411 .
  • the sound velocity film 413 provided between the support substrate 412 and the piezoelectric layer 411 reduces the sound velocity of the elastic wave.
  • Elastic waves have the property that their energy is concentrated in a medium that is inherently low in sound velocity. Therefore, the effect of confining the energy of the elastic wave in the piezoelectric layer 411 and the IDT electrode where the elastic wave is excited can be enhanced. As a result, the loss of the elastic wave filter 2 can be reduced and the Q value of the elastic wave filter 2 can be increased as compared with the case where the low sound velocity film 413 is not provided.
  • the material of the low-temperature film 413 is, for example, silicon oxide.
  • the material of the low-low-speed film 413 is not limited to silicon oxide. It may be a material that
  • the temperature characteristics can be improved.
  • the elastic constant of lithium tantalate has a negative temperature characteristic, and silicon oxide has a positive temperature characteristic. Therefore, the elastic wave filter 2 can reduce the absolute value of TCF.
  • the thickness of the low sound velocity film 413 is preferably 2.0 ⁇ or less, where ⁇ is the wavelength of the elastic wave determined by the electrode finger pitch.
  • the thickness of the low sound velocity film 413 is, for example, 670 nm.
  • the piezoelectric substrate 41 may include an adhesion layer interposed between the low-temperature velocity film 413 and the piezoelectric layer 411, for example.
  • the adhesion layer is made of, for example, resin (epoxy resin, polyimide resin, etc.), metal, or the like.
  • the piezoelectric substrate 41 is not limited to the adhesion layer, and the dielectric film is formed between the low-temperature velocity film 413 and the piezoelectric layer 411, above the piezoelectric layer 411, or under the low-temperature velocity film 413. You may prepare for either.
  • the high acoustic velocity film 414 is provided between the support substrate 412 and the low acoustic velocity film 413 .
  • the high acoustic velocity film 414 is provided on the support substrate 412 .
  • “Provided over the support substrate 412 ” includes the case of being directly provided over the support substrate 412 and the case of being indirectly provided over the support substrate 412 .
  • the high acoustic velocity film 414 is a film in which the sound velocity of bulk waves propagating through the high acoustic velocity film 414 is faster than the sound velocity of elastic waves propagating through the piezoelectric layer 411 .
  • the thickness of the high acoustic velocity film 414 is, for example, 200 nm, 300 nm, and 400 nm.
  • the high acoustic velocity film 414 functions to suppress the energy of the main mode elastic wave from leaking to the structure below the high acoustic velocity film 414 .
  • this acoustic wave filter 2 when the high acoustic velocity film 414 is sufficiently thick, the energy of the main mode elastic wave is distributed throughout the piezoelectric layer 411 and the low acoustic velocity film 413, and the low acoustic velocity of the high acoustic velocity film 414 It is distributed in a part of the film 413 side and is not distributed in the support substrate 412 .
  • the mechanism for confining the elastic wave by the high-speed film 414 is the same mechanism as in the case of Love wave type surface waves, which are non-leaky SH waves. Realize, p. 26-28. The above mechanism is different from the mechanism of confining elastic waves using a Bragg reflector made of an acoustic multilayer film.
  • the material of the high-sonic film 414 is, for example, diamond-like carbon, aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon, sapphire, piezoelectric material (lithium tantalate, lithium niobate, or crystal), alumina, zirconia, cordage. At least one material selected from the group consisting of light, mullite, steatite, forsterite, magnesia, and diamond.
  • the material of the high acoustic velocity film 414 may be a material containing any of the materials described above as a main component, or a material containing a mixture containing any of the materials described above as a main component.
  • the piezoelectric substrate 41 may have an adhesion layer, a dielectric film, etc. as films other than the high acoustic velocity film 414 , the low acoustic velocity film 413 and the piezoelectric layer 411 .
  • the high acoustic velocity film 414 may be omitted. That is, the low-temperature velocity film 413 may be provided between the piezoelectric layer 411 and the support substrate 412 .
  • the low sound velocity film 413 is made of silicon oxide, for example.
  • the support substrate 412 is a high acoustic velocity support substrate. In this case, the low sound velocity film 413 is laminated on the support substrate 412 which is the high sound velocity support substrate, and the piezoelectric layer 411 is laminated on the low sound velocity film 413 .
  • the piezoelectric substrate 41 comprises a piezoelectric layer 411 , a support substrate 412 and a low acoustic velocity film 413 . Also in this case, the change point P3 of the through-hole 70 exists within the support substrate 412 .
  • the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large, as in the above-described embodiment.
  • An elastic wave filter (2) of a first aspect comprises a piezoelectric substrate (41), a functional electrode (42), a conductive member (43), an external terminal (45), and vias (44).
  • the piezoelectric substrate (41) has a first major surface (41a) and a second major surface (41b) facing each other.
  • the piezoelectric substrate (41) has piezoelectricity at least partially in the thickness direction (D1).
  • the functional electrode (42) is arranged on the first main surface (41a) of the piezoelectric substrate (41).
  • a conductive member (43) is disposed on the first main surface (41a) of the piezoelectric substrate (41) and connected to the functional electrode (42).
  • the external terminals (45) are arranged on the second main surface (41b) of the piezoelectric substrate (41).
  • the via (44) penetrates the piezoelectric substrate (41) in the thickness direction (D1) and connects the external terminal (45) and the conductive member (43).
  • a first intersection point (P1) and a second intersection point (P2) are defined, and a change point (P3) is a point at which the inclination of the outer circumferential surface (44c) of the via (44) changes, and a first intersection point (P1).
  • a first angle ( ⁇ ) is an acute angle formed by a first line segment (H1) connecting the point of change (P3) and the second intersection (P2) and the second main surface (41b).
  • a second angle ( ⁇ ) is an acute angle formed by a second line segment connecting the first intersection point (P1) and the imaginary line (L1).
  • the imaginary line (L1) passes through the point of change (P3) and is parallel to the second main surface (41b) of the piezoelectric substrate (41).
  • the second angle ( ⁇ ) is greater than the first angle ( ⁇ ).
  • the second angle ( ⁇ ) is larger than the first angle ( ⁇ ).
  • the width (W1) of the via (44) on the first main surface (41a) of the piezoelectric substrate (41) can be increased.
  • the contact area between the via (44) and the conductive member (43) can be made relatively large.
  • the piezoelectric substrate (41) has a piezoelectric layer (411) and a support substrate (412).
  • the support substrate (412) is arranged on the piezoelectric layer (411) on the side of the external terminal (45).
  • the contact area between the via (44) and the conductive member (43) can be made relatively large.
  • the change point (P3) exists within the support substrate (412).
  • the contact area between the via (44) and the conductive member (43) can be increased in the configuration where the change point (P3) exists within the piezoelectric layer (411).
  • the piezoelectric layer (411) is lithium tantalate or lithium niobate.
  • the contact area between the via (44) and the conductive member (43) can be made relatively large.
  • the supporting substrate (412) is silicon or sapphire.
  • the contact area between the via (44) and the conductive member (43) can be made relatively large in the configuration where the supporting substrate (412) is silicon or sapphire.
  • the elastic wave filter (2) of the sixth aspect comprises a peripheral wall (47) and a cover member (48) in any one of the first to fifth aspects.
  • a peripheral wall (47) is disposed on the first major surface (41a) of the piezoelectric substrate (41) and surrounds the functional electrode (42) and the conductive member (43).
  • the cover member (48) covers the opening of the peripheral wall (47) on the side opposite to the first main surface (41a).
  • the contact area between the via (44) and the conductive member (43) can be made relatively large in the configuration including the peripheral wall (47) and the cover member (48).
  • the method for manufacturing the elastic wave filter (2) of the seventh aspect includes a first step, a second step, a third step, and a fourth step.
  • a substrate (410) is provided.
  • the substrate (410) has a first main surface (410a) and a second main surface (410b) facing each other, and has piezoelectricity in at least a part of the thickness direction.
  • a functional electrode (42) and a conductive member (43) connected to the functional electrode (42) are arranged on the substrate (410) on the first main surface (410a).
  • a piezoelectric substrate (41) having a through hole (70) penetrating in the thickness direction is formed in the substrate (410).
  • a via (44) is formed inside the through hole (70) of the piezoelectric substrate (41) so as to connect to the conductive member (43).
  • a plurality of external terminals (45) including at least one external terminal (45) connected to vias (44) are formed on the main surface (41b) of the piezoelectric substrate (41).
  • a hole is formed by laser processing from the second main surface (410b) of the substrate (410) to a position between the first main surface (410a) and the second main surface (410b) of the substrate (410). forming part (60); Then, by dry etching, a through hole (70) is formed by penetrating between the bottom surface (60a) of the hole (60) and the first main surface (410a) of the substrate (410).
  • a via (44) having a second angle ( ⁇ ) larger than the first angle ( ⁇ ) can be formed.
  • the first main surface (41a) of the piezoelectric substrate (41) The width (W1) of the via (44) can be increased.
  • the contact area between the via (44) and the conductive member (43) can be made relatively large.
  • a high-frequency module (1) of an eighth aspect comprises an acoustic wave filter (2) of any one of the first to sixth aspects and a mounting substrate (11).
  • a mounting substrate (11) mounts an elastic wave filter (2).
  • a communication device (100) of the ninth aspect comprises the high-frequency module (1) of the eighth aspect and a signal processing circuit (20).
  • a signal processing circuit (20) is connected to the high frequency module (1) and processes a high frequency signal.

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Abstract

An elastic wave filter having increased reliability of connection of a via and an electrically conductive member and capable of suppressing degradation of filter characteristics is provided. The elastic wave filter (2) is provided with a piezoelectric substrate (41), an IDT electrode (42), an electrically conductive member (43), an external terminal (45), and a via (44). The via (44) extends through the piezoelectric substrate (41) in a thickness direction (D1), and connects the external terminal (45) and the electrically conductive member (43). In a cross section view of the piezoelectric substrate (41): the via (44) intersects a first main surface (41a) and a second main surface (41b) at a first intersecting point (P1) and a second intersecting point (P2), respectively; the via (44) has an outer peripheral surface (44c) with an inclination changing at a change point (P3); the change point (P3) and the second intersecting point (P2) are connected by a first line segment (H1) forming an acute angle of a first angle (α) with the second main surface (41b); and the change point (P3) and the first intersecting point (P1) are connected by a second line segment (H2) forming an acute angle of a second angle (β) with a virtual line (L1). The virtual line (L1) passes through the change point (P3) and is parallel to the second main surface (41b). The second angle (β) is greater than the first angle (α).

Description

弾性波フィルタ、弾性波フィルタの製造方法、高周波モジュール及び通信装置Elastic wave filter, method for manufacturing elastic wave filter, high frequency module, and communication device
　本発明は、弾性波フィルタ、弾性波フィルタの製造方法、高周波モジュール及び通信装置に関する。特に、本発明は、圧電性基板において厚さ方向に貫通するビアが設けられた弾性波フィルタ、当該弾性波フィルタを製造する弾性波フィルタの製造方法、当該弾性波フィルタを備える高周波モジュール、及び当該高周波モジュールを備える通信装置に関する。 The present invention relates to an elastic wave filter, an elastic wave filter manufacturing method, a high frequency module, and a communication device. In particular, the present invention provides an acoustic wave filter provided with vias penetrating in the thickness direction in a piezoelectric substrate, a method for manufacturing the acoustic wave filter, a high frequency module including the acoustic wave filter, and the The present invention relates to a communication device having a high frequency module.
　特許文献１に記載の電子デバイス（弾性波フィルタ）は、底面及び頂面を有する第１基板（圧電性基板）を備える。第１基板には、電子回路及びビアが形成されている。電子回路は、第１基板の底面に形成されている。ビアは、第１基板の底面と頂面との間を貫通している。第１基板の底面におけるビア上には、ストッパ層（導電部材）が形成されている。第１基板の頂面におけるビア上には、外部電極層が形成されている。この電子デバイスでは、第１基板におけるビアを形成する部分には、レーザ加工によってスルーホールが形成されている。 The electronic device (acoustic wave filter) described in Patent Document 1 includes a first substrate (piezoelectric substrate) having a bottom surface and a top surface. Electronic circuits and vias are formed in the first substrate. An electronic circuit is formed on the bottom surface of the first substrate. A via penetrates between the bottom surface and the top surface of the first substrate. A stopper layer (conductive member) is formed on the via on the bottom surface of the first substrate. An external electrode layer is formed on the via on the top surface of the first substrate. In this electronic device, a through hole is formed by laser processing in the portion of the first substrate where the via is to be formed.
特開２０１８－１１３６７９号公報JP 2018-113679 A
　特許文献１では、スルーホールは、第１基板の頂面側（外部電極層側）からレーザ加工によって形成されるため、スルーホールの幅は、第１基板の底面側（ストッパ層側）に行くほど細くなる。したがって、ビアの幅も、第１基板の底面側（ストッパ層側）に行くほど細くなる。このため、ビアとストッパ層（導電部材）との接触面積が比較的小さくなる。この結果、ビアとストッパ層との接続信頼性が低下したり、電子デバイスがフィルタである場合は、フィルタ特性が劣化したりする。 In Patent Document 1, since the through-hole is formed by laser processing from the top surface side (external electrode layer side) of the first substrate, the width of the through-hole goes to the bottom surface side (stopper layer side) of the first substrate. becomes thinner. Therefore, the width of the via also becomes narrower toward the bottom surface side (stopper layer side) of the first substrate. Therefore, the contact area between the via and the stopper layer (conductive member) is relatively small. As a result, the connection reliability between the via and the stopper layer is lowered, and if the electronic device is a filter, the filter characteristics are degraded.
　本発明の目的は、ビアと導電部材との接続信頼性を向上できかつフィルタ特性の劣化を抑制できる、弾性波フィルタ、弾性波フィルタの製造方法、高周波モジュール及び通信装置を提供することである。 An object of the present invention is to provide an elastic wave filter, an elastic wave filter manufacturing method, a high frequency module, and a communication device that can improve connection reliability between vias and conductive members and suppress deterioration of filter characteristics.
　本発明の一態様の弾性波フィルタは、圧電性基板と、機能電極と、導電部材と、外部端子と、ビアと、を備える。前記圧電性基板は、互いに対向する第１主面及び第２主面を有する。前記圧電性基板は、厚さ方向の少なくとも一部に圧電性を有する。前記機能電極は、前記圧電性基板の前記第１主面に配置されている。前記導電部材は、前記圧電性基板の前記第１主面に配置され、前記機能電極に接続されている。前記外部端子は、前記圧電性基板の前記第２主面に配置されている。前記ビアは、前記圧電性基板を厚さ方向に貫通し、前記外部端子と前記導電部材とを接続する。前記第２主面に直交する断面での断面視において、前記ビアと前記圧電性基板の前記第１主面及び前記第２主面との交点をそれぞれ第１交点及び第２交点とし、前記ビアの外周面において前記外周面の傾斜が変化する点を変化点とし、前記第１交点、前記第２交点及び前記変化点は、前記圧電性基板の前記第２主面に平行な方向において前記ビアにおける互いに同じ側にあり、前記変化点と前記第２交点とを結ぶ第１線分と前記第２主面とが成す鋭角を第１角とし、前記変化点と前記第１交点とを結ぶ第２線分と、前記変化点を通って前記圧電性基板の前記第２主面に平行な仮想線とが成す鋭角を第２角とする。前記第２角は、前記第１角よりも大きい。 An acoustic wave filter of one aspect of the present invention includes a piezoelectric substrate, functional electrodes, conductive members, external terminals, and vias. The piezoelectric substrate has a first main surface and a second main surface facing each other. The piezoelectric substrate has piezoelectricity at least partially in the thickness direction. The functional electrode is arranged on the first main surface of the piezoelectric substrate. The conductive member is arranged on the first main surface of the piezoelectric substrate and connected to the functional electrode. The external terminals are arranged on the second main surface of the piezoelectric substrate. The via passes through the piezoelectric substrate in the thickness direction and connects the external terminal and the conductive member. In a cross-sectional view in a cross section perpendicular to the second main surface, intersections between the via and the first main surface and the second main surface of the piezoelectric substrate are defined as first intersections and second intersections, respectively, and the via A change point is a point where the inclination of the outer peripheral surface changes on the outer peripheral surface of the via, and the first intersection, the second intersection, and the change point are in the direction parallel to the second main surface of the piezoelectric substrate. A first angle is an acute angle formed by a first line segment connecting the change point and the second intersection point and the second main surface on the same side, and a first angle is defined as a first angle connecting the change point and the first intersection An acute angle formed by two line segments and an imaginary line passing through the change point and parallel to the second main surface of the piezoelectric substrate is defined as a second angle. The second angle is larger than the first angle.
　本発明の一態様の弾性波フィルタの製造方法は、第１工程と、第２工程と、第３工程と、第４工程とを備える。前記第１工程では、基板を用意する。前記基板は、互いに対向する第１主面及び第２主面を有し、厚さ方向の少なくとも一部に圧電性を有する基板であって、前記第１主面において機能電極及び前記機能電極に接続された導電部材が配置されている。前記第２工程では、前記基板において厚さ方向に貫通する貫通孔を有する圧電性基板を形成する。前記第３工程では、前記圧電性基板の前記貫通孔において、前記導電部材に接続するようにビアを形成する。前記第４工程では、前記圧電性基板の主面に、前記ビアに接続する外部端子を少なくとも１つ含む複数の外部端子を形成する。前記第２工程では、レーザ加工によって、前記基板の前記第２主面から前記基板の前記第１主面と前記第２主面との間の位置までの穴部を形成する。そして、ドライエッチングによって、前記穴部の底面と前記基板の前記第１主面との間を貫通させることで、前記貫通孔を形成する。 A method for manufacturing an elastic wave filter according to one aspect of the present invention includes a first step, a second step, a third step, and a fourth step. In the first step, a substrate is prepared. The substrate has a first main surface and a second main surface facing each other, and has piezoelectricity in at least a part of a thickness direction, and the functional electrode and the functional electrode are formed on the first main surface. A connected conductive member is disposed. In the second step, a piezoelectric substrate having a through hole penetrating in the thickness direction of the substrate is formed. In the third step, a via is formed in the through hole of the piezoelectric substrate so as to be connected to the conductive member. In the fourth step, a plurality of external terminals including at least one external terminal connected to the via are formed on the main surface of the piezoelectric substrate. In the second step, a hole is formed from the second main surface of the substrate to a position between the first main surface and the second main surface of the substrate by laser processing. Then, by dry etching, the through hole is formed by penetrating between the bottom surface of the hole and the first main surface of the substrate.
　本発明の一態様の高周波モジュールは、前記弾性波フィルタと、実装基板と、を備える。前記実装基板は、前記弾性波フィルタを実装する。 A high-frequency module of one aspect of the present invention includes the elastic wave filter and a mounting substrate. The mounting board mounts the elastic wave filter.
　本発明の一態様の通信装置は、前記高周波モジュールと、信号処理回路と、を備える。前記信号処理回路は、前記高周波モジュールに接続されており、高周波信号を信号処理する。 A communication device according to one aspect of the present invention includes the high-frequency module and a signal processing circuit. The signal processing circuit is connected to the high frequency module and processes a high frequency signal.
　本発明によれば、ビアと導電部材との接続信頼性を向上できかつフィルタ特性の劣化を抑制できる、という利点がある。 　According to the present invention, there is an advantage that it is possible to improve the connection reliability between the via and the conductive member and suppress deterioration of the filter characteristics.
図１は、実施形態に係る高周波モジュール及び通信装置のブロック図である。FIG. 1 is a block diagram of a high frequency module and communication device according to an embodiment. 図２は、実施形態に係る弾性波フィルタの平面図である。FIG. 2 is a plan view of the elastic wave filter according to the embodiment. 図３は、図２のＸ１－Ｘ１断面図である。FIG. 3 is a cross-sectional view taken along line X1-X1 in FIG. 図４は、図３の部分拡大図である。4 is a partially enlarged view of FIG. 3. FIG. 図５Ａは、弾性波フィルタの製造方法の電極形成工程を説明する説明図である。図５Ｂは、弾性波フィルタの製造方法のカバー部材形成工程を説明する説明図である。図５Ｃは、弾性波フィルタの製造方法の穴部形成工程を説明する説明図である。図５Ｄは、弾性波フィルタの製造方法の貫通孔形成工程を説明する説明図である。FIG. 5A is an explanatory diagram illustrating an electrode forming step in the method for manufacturing an elastic wave filter. FIG. 5B is an explanatory diagram illustrating a cover member forming step in the method for manufacturing an elastic wave filter. FIG. 5C is an explanatory diagram illustrating a hole forming step in the method of manufacturing an elastic wave filter. FIG. 5D is an explanatory diagram illustrating a through-hole forming step in the method for manufacturing an elastic wave filter. 図６Ａは、弾性波フィルタの製造方法のビア形成工程を説明する説明図である。図６Ｂは、弾性波フィルタの製造方法の接合層形成工程を説明する説明図である。図６Ｃは、弾性波フィルタの製造方法の外部端子形成工程を説明する説明図である。FIG. 6A is an explanatory diagram illustrating a via formation step in the method of manufacturing an acoustic wave filter. FIG. 6B is an explanatory diagram illustrating a bonding layer forming step in the method for manufacturing an elastic wave filter. FIG. 6C is an explanatory diagram for explaining the external terminal forming step of the method of manufacturing the elastic wave filter. 図７は、変形例１に係る弾性波フィルタの断面図である。FIG. 7 is a cross-sectional view of an acoustic wave filter according to Modification 1. FIG. 図８は、変形例２に係る弾性波フィルタの断面図である。FIG. 8 is a cross-sectional view of an acoustic wave filter according to Modification 2. FIG.
　以下の実施形態等において参照する図１～図８は、いずれも模式的な図であり、図中の各構成要素の大きさや厚さそれぞれの比が、必ずしも実際の寸法比を反映しているとは限らない。 1 to 8 referred to in the following embodiments and the like are all schematic diagrams, and the ratio of the size and thickness of each component in the diagram does not necessarily reflect the actual dimensional ratio. Not necessarily.
　（実施形態）
　（１）概要
　本実施形態に係る弾性波フィルタ２は、図２及び図３に示すように、圧電性基板４１と、ＩＤＴ電極４２（機能電極）と、複数の導電補助部材（導電部材）４３と、複数の外部端子４５と、複数のビア４４と、を備える。圧電性基板４１は、互いに対向する第１主面４１ａ及び第２主面４１ｂを有する。圧電性基板４１は、厚さ方向Ｄ１の少なくとも一部に圧電性を有する。本実施形態では、圧電性基板４１は、厚さ方向Ｄ１の全てに圧電性を有する。ＩＤＴ電極４２は、圧電性基板４１の第１主面４１ａに配置されている。導電補助部材４３は、圧電性基板４１の第１主面４１ａに配置されており、ＩＤＴ電極４２に接続されている。複数の外部端子４５は、圧電性基板４１の第２主面４１ｂに配置されている。複数のビア４４は、圧電性基板４１を厚さ方向Ｄ１に貫通し、複数の外部端子４５の少なくとも１つと導電補助部材４３とを接続している。図３及び図４に示すように、第２主面４１ｂに直交する断面での断面視において、ビア４４と圧電性基板４１の第１主面４１ａとの交点を第１交点Ｐ１とし、ビア４４と圧電性基板４１の第２主面４１ｂとの交点を第２交点Ｐ２とし、ビア４４の外周面４４ｃにおいて外周面４４ｃの傾斜が変化する点を変化点Ｐ３とする。第１交点Ｐ１、第２交点Ｐ２及び変化点Ｐ３は、圧電性基板４の第２主面４１ｂに平行な方向においてビア４４における互いに同じ側にある。変化点Ｐ３と第２交点Ｐ２とを結ぶ第１線分Ｈ１と圧電性基板４１の第２主面４１ｂとが成す鋭角を第１角αとし、変化点Ｐ３と第１交点Ｐ１とを結ぶ第２線分Ｈ２と仮想線Ｌ１とが成す鋭角を第２角βとする。仮想線Ｌ１は、変化点Ｐ３を通って圧電性基板４１の第２主面４１ｂに平行である。第２角βは、第１角αよりも大きい。 (embodiment)
(1) Outline As shown in FIGS. 2 and 3, the elastic wave filter 2 according to the present embodiment includes a piezoelectric substrate 41, an IDT electrode 42 (functional electrode), and a plurality of conductive auxiliary members (conductive members) 43. , a plurality of external terminals 45 , and a plurality of vias 44 . The piezoelectric substrate 41 has a first major surface 41a and a second major surface 41b facing each other. The piezoelectric substrate 41 has piezoelectricity at least partially in the thickness direction D1. In this embodiment, the piezoelectric substrate 41 has piezoelectricity in the entire thickness direction D1. The IDT electrode 42 is arranged on the first main surface 41 a of the piezoelectric substrate 41 . The conductive auxiliary member 43 is arranged on the first main surface 41 a of the piezoelectric substrate 41 and connected to the IDT electrode 42 . A plurality of external terminals 45 are arranged on the second main surface 41 b of the piezoelectric substrate 41 . A plurality of vias 44 pass through the piezoelectric substrate 41 in the thickness direction D<b>1 and connect at least one of the plurality of external terminals 45 and the conductive auxiliary member 43 . As shown in FIGS. 3 and 4, in a cross-sectional view perpendicular to the second principal surface 41b, the intersection of the via 44 and the first principal surface 41a of the piezoelectric substrate 41 is defined as a first intersection point P1, and the via 44 and the second principal surface 41b of the piezoelectric substrate 41 is defined as a second intersection point P2, and a point where the inclination of the outer circumferential surface 44c of the via 44 changes is defined as a change point P3. The first intersection point P1, the second intersection point P2, and the change point P3 are on the same side of the via 44 in the direction parallel to the second main surface 41b of the piezoelectric substrate 4 . An acute angle formed by a first line segment H1 connecting the change point P3 and the second intersection point P2 and the second main surface 41b of the piezoelectric substrate 41 is defined as a first angle α, and an acute angle connecting the change point P3 and the first intersection point P1 is defined as a first angle α. The acute angle formed by the two line segments H2 and the virtual line L1 is defined as a second angle β. The virtual line L1 is parallel to the second main surface 41b of the piezoelectric substrate 41 through the change point P3. The second angle β is greater than the first angle α.
　この構成によれば、第２角βが第１角αよりも大きいため、第２角βと第１角αとが同じ大きさである場合と比べて、上記の断面視における圧電性基板４１の第１主面４１ａでのビア４４の幅Ｗ１を大きくすることができる。これにより、ビア４４と導電補助部材４３との接触面積を比較的大きくすることができる。この結果、ビア４４と導電補助部材４３との接続信頼性を向上できる。かつ、ビア４４と導電補助部材４３との接触部分での電気抵抗及びインダクタンスを低減でき、これによりフィルタ特性の劣化を抑制できる。 According to this configuration, the second angle β is larger than the first angle α. The width W1 of the via 44 at the first main surface 41a of can be increased. Thereby, the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large. As a result, connection reliability between the via 44 and the conductive auxiliary member 43 can be improved. Moreover, the electrical resistance and inductance at the contact portion between the via 44 and the conductive auxiliary member 43 can be reduced, thereby suppressing deterioration of filter characteristics.
　（２）詳細説明
　以下、本実施形態に係る弾性波フィルタ２、弾性波フィルタ２の製造方法、弾性波フィルタ２を備えた高周波モジュール１、及び高周波モジュール１を備えた通信装置１００について、図１～図６Ｃを参照して詳しく説明する。 (2) Detailed Description Hereinafter, the elastic wave filter 2 according to the present embodiment, the method for manufacturing the elastic wave filter 2, the high frequency module 1 including the elastic wave filter 2, and the communication device 100 including the high frequency module 1 will be described with reference to FIG. A detailed description will be given with reference to FIG. 6C.
　（２－１）通信装置の構成
　図１に示すように、本実施形態に係る通信装置１００は、高周波モジュール１を備える通信装置である。通信装置１００は、例えば携帯端末（例えばスマートフォン）であるが、これに限らず、例えばウェアラブル端末（例えばスマートウォッチ）であってもよい。高周波モジュール１は、例えば、４Ｇ（第４世代移動通信）規格及び５Ｇ（第５世代移動通信）規格に対応可能なモジュールである。４Ｇ規格は、例えば、３ＧＰＰ（Third Generation Partnership Project）　ＬＴＥ（Long Term Evolution）規格である。５Ｇ規格は、例えば、５Ｇ　ＮＲ（New Radio）である。高周波モジュール１は、キャリアアグリゲーション及びデュアルコネクティビティに対応可能なモジュールである。 (2-1) Configuration of Communication Apparatus As shown in FIG. The communication device 100 is, for example, a mobile terminal (eg, smart phone), but is not limited to this, and may be, for example, a wearable terminal (eg, smart watch). The high-frequency module 1 is a module compatible with, for example, the 4G (fourth generation mobile communication) standard and the 5G (fifth generation mobile communication) standard. The 4G standard is, for example, the 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) standard. The 5G standard is, for example, 5G NR (New Radio). The radio frequency module 1 is a module capable of supporting carrier aggregation and dual connectivity.
　通信装置１００は、高周波モジュール１の他に、信号処理回路２０と、１つ以上（図示例では１つ）のアンテナ４０とを備える。 The communication device 100 includes a signal processing circuit 20 and one or more (one in the illustrated example) antennas 40 in addition to the high frequency module 1 .
　高周波モジュール１は、アンテナ４０で受信された受信信号（高周波信号）を増幅して信号処理回路２０に出力するように構成されている。また、高周波モジュール１は、信号処理回路２０からの送信信号（高周波信号）を増幅してアンテナ４０に出力するように構成されている。高周波モジュール１は、例えば、信号処理回路２０によって制御される。 The high-frequency module 1 is configured to amplify a received signal (high-frequency signal) received by the antenna 40 and output it to the signal processing circuit 20 . The high frequency module 1 is also configured to amplify a transmission signal (high frequency signal) from the signal processing circuit 20 and output the amplified signal to the antenna 40 . The high frequency module 1 is controlled by a signal processing circuit 20, for example.
　信号処理回路２０は、高周波モジュール１に接続されており、高周波モジュール１から受け取る受信信号を信号処理するように構成されている。また、信号処理回路２０は、高周波モジュール１に出力する送信信号を信号処理するように構成されている。信号処理回路２０は、ＲＦ信号処理回路２１とベースバンド信号処理回路２２とを含む。 The signal processing circuit 20 is connected to the high frequency module 1 and configured to process the received signal received from the high frequency module 1 . Further, the signal processing circuit 20 is configured to process the transmission signal to be output to the high frequency module 1 . The signal processing circuit 20 includes an RF signal processing circuit 21 and a baseband signal processing circuit 22 .
　ＲＦ信号処理回路２１は、例えばＲＦＩＣ（Radio Frequency Integrated Circuit）であり、高周波信号（受信信号及び送信信号）に対して信号処理を行う。ＲＦ信号処理回路２１は、例えば、高周波モジュール１から受け取った受信信号を、ダウンコンバート等の信号処理を行ってベースバンド信号処理回路２２に出力する。また、ＲＦ信号処理回路２１は、ベースバンド信号処理回路２２から出力された送信信号をアップコンバート等の信号処理を行って高周波モジュール１に出力する。 The RF signal processing circuit 21 is, for example, an RFIC (Radio Frequency Integrated Circuit), and performs signal processing on high-frequency signals (received signals and transmitted signals). The RF signal processing circuit 21 , for example, performs signal processing such as down-conversion on the received signal received from the high-frequency module 1 and outputs the processed signal to the baseband signal processing circuit 22 . Further, the RF signal processing circuit 21 performs signal processing such as up-conversion on the transmission signal output from the baseband signal processing circuit 22 and outputs the signal to the high frequency module 1 .
　ベースバンド信号処理回路２２は、例えばＢＢＩＣ（Baseband Integrated Circuit）である。ベースバンド信号処理回路２２は、ＲＦ信号処理回路２１から受け取った受信信号を外部に出力する。この出力信号（受信信号）は、例えば、画像信号として画像表示のために、又は、音声信号として通話のために使用可能である。また、ベースバンド信号処理回路２２は、外部から入力されたベースバンド信号（例えば音声信号及び画像信号）から送信信号を生成し、生成した送信信号をＲＦ信号処理回路２１に出力する。 The baseband signal processing circuit 22 is, for example, a BBIC (Baseband Integrated Circuit). The baseband signal processing circuit 22 outputs the reception signal received from the RF signal processing circuit 21 to the outside. This output signal (received signal) can be used, for example, as an image signal for image display, or as an audio signal for communication. The baseband signal processing circuit 22 also generates a transmission signal from an externally input baseband signal (for example, an audio signal and an image signal) and outputs the generated transmission signal to the RF signal processing circuit 21 .
　（２－２）高周波モジュールの回路構成
　本実施形態の高周波モジュール１の回路構成の一例を説明する。図１に示すように、高周波モジュール１は、信号処理回路２０とアンテナ４０との間で高周波信号（例えば受信信号及び送信信号）を伝達する。高周波モジュール１は、電子部品として、例えば、スイッチ３と、受信フィルタ４と、送信フィルタ５と、整合回路６，７と、ローノイズアンプ８と、パワーアンプ９とを備える。受信フィルタ４及び送信フィルタ５は、本実施形態の弾性波フィルタ２の一例である。また、高周波モジュール１は、複数（例えば３つ）の外部接続端子１０を備える。また、高周波モジュール１は、複数（例えば３つ）の信号経路Ｒ１～Ｒ３を備える。また、高周波モジュール１は、図３に示すように、上記の電子部品及び外部接続端子１０を実装する実装基板１１を備える。実装基板１１は、互いに対向する第１主面１１ａ及び第２主面（図示せず）を有する。上記の電子部品及び外部接続端子１０は、実装基板１１の第１主面１１ａ又は第２主面に実装されている。 (2-2) Circuit Configuration of High-Frequency Module An example of the circuit configuration of the high-frequency module 1 of the present embodiment will be described. As shown in FIG. 1, the high-frequency module 1 transmits high-frequency signals (for example, received signals and transmitted signals) between the signal processing circuit 20 and the antenna 40 . The high frequency module 1 includes, for example, a switch 3, a reception filter 4, a transmission filter 5, matching circuits 6 and 7, a low noise amplifier 8, and a power amplifier 9 as electronic components. The reception filter 4 and the transmission filter 5 are examples of the elastic wave filter 2 of this embodiment. The high-frequency module 1 also includes a plurality of (for example, three) external connection terminals 10 . The high-frequency module 1 also includes a plurality (eg, three) of signal paths R1 to R3. The high-frequency module 1 also includes a mounting board 11 on which the electronic components and the external connection terminals 10 are mounted, as shown in FIG. The mounting substrate 11 has a first major surface 11a and a second major surface (not shown) facing each other. The electronic components and external connection terminals 10 described above are mounted on the first main surface 11a or the second main surface of the mounting board 11 .
　（２－２－１）外部接続端子
　複数の外部接続端子１０は、図１に示すように、アンテナ端子１０Ａと、信号出力端子１０Ｂと、信号入力端子１０Ｃとを含む。アンテナ端子１０Ａは、アンテナ４０が接続される端子である。信号出力端子１０Ｂは、高周波モジュール１が処理した受信信号を信号処理回路２０に出力するための端子であり、信号処理回路２０に接続されている。信号入力端子１０Ｃは、信号処理回路２０からの送信信号が入力されるための端子であり、信号処理回路２０に接続されている。 (2-2-1) External Connection Terminals As shown in FIG. 1, the plurality of external connection terminals 10 include an antenna terminal 10A, a signal output terminal 10B, and a signal input terminal 10C. The antenna terminal 10A is a terminal to which the antenna 40 is connected. The signal output terminal 10B is a terminal for outputting the received signal processed by the high frequency module 1 to the signal processing circuit 20, and is connected to the signal processing circuit 20. FIG. The signal input terminal 10</b>C is a terminal for receiving a transmission signal from the signal processing circuit 20 and is connected to the signal processing circuit 20 .
　（２－２－２）信号経路
　信号経路Ｒ１～Ｒ３は、信号（受信信号又は送信信号）が入力又は出力されるための複数の外部接続端子１０を繋ぐ信号経路Ｒ０を構成する。すなわち、信号経路Ｒ１～Ｒ３は、信号経路Ｒ０の一部である。信号経路Ｒ０は、アンテナ端子１０Ａを通る信号が流れる信号経路である。信号経路Ｒ１は、アンテナ端子１０Ａとスイッチ３の共通端子３ａとを繋ぐ信号経路である。信号経路Ｒ２は、スイッチ３の選択端子３ｂと信号出力端子１０Ｂとを繋ぐ信号経路である。信号経路Ｒ２には、受信フィルタ４、整合回路６及びローノイズアンプ８が設けられている。信号経路Ｒ３は、スイッチ３の選択端子３ｃと信号入力端子１０Ｃとを繋ぐ信号経路である。信号経路Ｒ３には、送信フィルタ５、整合回路７及びパワーアンプ９が設けられている。 (2-2-2) Signal Path The signal paths R1 to R3 constitute a signal path R0 connecting a plurality of external connection terminals 10 for inputting or outputting signals (received signals or transmitted signals). That is, signal paths R1-R3 are part of signal path R0. A signal path R0 is a signal path through which a signal passing through the antenna terminal 10A flows. A signal path R1 is a signal path that connects the antenna terminal 10A and the common terminal 3a of the switch 3 . A signal path R2 is a signal path that connects the selection terminal 3b of the switch 3 and the signal output terminal 10B. A reception filter 4, a matching circuit 6, and a low noise amplifier 8 are provided in the signal path R2. A signal path R3 is a signal path that connects the selection terminal 3c of the switch 3 and the signal input terminal 10C. A transmission filter 5, a matching circuit 7, and a power amplifier 9 are provided in the signal path R3.
　（２－２－３）スイッチ
　スイッチ３は、複数の信号経路Ｒ１，Ｒ２の中から、受信信号の受信又は送信信号の送信で使用する信号経路を選択し、選択した信号経路を、アンテナ端子１０Ａと繋がる信号経路Ｒ１に接続する。スイッチ３は、例えばスイッチＩＣ（Integrated Circuit）である。スイッチ３は、１つ以上（例えば１つ）の共通端子３ａと、２つ以上（図示例では２つ）の選択端子３ｂ，３ｃとを有する。共通端子３ａは、信号経路Ｒ１を介してアンテナ端子１０Ａに接続されている。選択端子３ｂは、信号経路Ｒ２を介して受信フィルタ４の入力部に接続されており、選択端子３ｃは、信号経路Ｒ３を介して送信フィルタ５の出力部に接続されている。スイッチ３は、複数の選択端子３ｂ，３ｃの中から共通端子３ａに接続される選択端子を１つ選択する。 (2-2-3) Switch The switch 3 selects a signal path used for receiving a received signal or transmitting a transmitted signal from among the plurality of signal paths R1 and R2, and connects the selected signal path to the antenna terminal 10A. is connected to the signal path R1 connected to the . The switch 3 is, for example, a switch IC (Integrated Circuit). The switch 3 has one or more (for example, one) common terminal 3a and two or more (two in the illustrated example) selection terminals 3b and 3c. The common terminal 3a is connected to the antenna terminal 10A via the signal path R1. The selection terminal 3b is connected to the input of the reception filter 4 via the signal path R2, and the selection terminal 3c is connected to the output of the transmission filter 5 via the signal path R3. The switch 3 selects one selection terminal connected to the common terminal 3a from among the plurality of selection terminals 3b and 3c.
　（２－２－４）受信フィルタ及び送信フィルタ
　受信フィルタ４は、信号経路Ｒ２に設けられており、信号経路Ｒ２を流れる信号を通過させる。受信フィルタ４は、第１通信バンドの信号を通過させる第１通過帯域を有する。受信フィルタ４は、入力部（図示せず）と出力部（図示せず）とを有する。受信フィルタ４の入力部は、スイッチの選択端子３ｂに接続されており、受信フィルタ４の出力部は、整合回路６に接続されている。受信フィルタ４は、入力部に入力された受信信号を第１通過帯域の信号に制限して出力部から出力する。 (2-2-4) Receiving Filter and Transmitting Filter The receiving filter 4 is provided on the signal path R2 and passes the signal flowing through the signal path R2. The receive filter 4 has a first passband for passing signals in the first communication band. The receive filter 4 has an input section (not shown) and an output section (not shown). The input portion of the reception filter 4 is connected to the selection terminal 3b of the switch, and the output portion of the reception filter 4 is connected to the matching circuit 6. FIG. The reception filter 4 limits the reception signal input to the input section to a signal in the first passband and outputs the signal from the output section.
　送信フィルタ５は、信号経路Ｒ３に設けられており、信号経路Ｒ３を流れる信号を通過させる。送信フィルタ５は、第２通信バンドの信号を通過させる第２通過帯域を有する。送信フィルタ５は、入力部（図示せず）と出力部（図示せず）とを有する。送信フィルタ５の入力部は、整合回路７に接続されており、送信フィルタ５の出力部は、スイッチ３の選択端子３ｃに接続されている。送信フィルタ５は、送信フィルタ５の入力部に入力された送信信号を第２通過帯域の信号に制限して送信フィルタ５の出力部から出力する。 The transmission filter 5 is provided on the signal route R3 and passes the signal flowing through the signal route R3. The transmit filter 5 has a second passband that passes signals in the second communication band. The transmit filter 5 has an input (not shown) and an output (not shown). An input portion of the transmission filter 5 is connected to the matching circuit 7 , and an output portion of the transmission filter 5 is connected to the selection terminal 3 c of the switch 3 . The transmission filter 5 limits the transmission signal input to the input section of the transmission filter 5 to a signal in the second passband and outputs the signal from the output section of the transmission filter 5 .
　受信フィルタ４及び送信フィルタ５はそれぞれ、弾性波フィルタ２によって構成されている。弾性波フィルタ２は、例えば、弾性表面波を利用する表面弾性波（ＳＡＷ：Surface Acoustic Wave）フィルタである。弾性波フィルタ２は、複数の弾性波共振子を有する。各弾性波共振子は、圧電性基板４１と、圧電性基板４１に形成されたＩＤＴ電極４２（機能電極）とを有する。複数の弾性波共振子は、直列腕共振子及び並列腕共振子を有するラダー型回路を構成する。なお、弾性波フィルタ２は、ＳＡＷフィルタに限定されず、ＳＡＷフィルタ以外に例えばＢＡＷ（Bulk Acoustic Wave）フィルタであってもよい。 The reception filter 4 and the transmission filter 5 are each composed of an acoustic wave filter 2. The acoustic wave filter 2 is, for example, a surface acoustic wave (SAW) filter that utilizes surface acoustic waves. The elastic wave filter 2 has a plurality of elastic wave resonators. Each elastic wave resonator has a piezoelectric substrate 41 and an IDT electrode 42 (functional electrode) formed on the piezoelectric substrate 41 . A plurality of acoustic wave resonators form a ladder-type circuit having series arm resonators and parallel arm resonators. Note that the elastic wave filter 2 is not limited to a SAW filter, and may be, for example, a BAW (Bulk Acoustic Wave) filter other than a SAW filter.
　（２－２－５）ローノイズアンプ及びパワーアンプ
　ローノイズアンプ８は、信号経路Ｒ２に設けられている。ローノイズアンプ８は、入力部（図示せず）及び出力部（図示せず）を有する。入力部は、整合回路６に接続されており、出力部は、信号出力端子１０Ｂに接続されている。ローノイズアンプ８は、入力部に入力された受信信号を増幅して出力部から出力する。パワーアンプ９は、信号経路Ｒ３に設けられている。パワーアンプ９は、入力部（図示せず）及び出力部（図示せず）を有する。入力部は、信号入力端子１０Ｃに接続されている。出力部は、整合回路７に接続されている。パワーアンプ９は、入力部に入力された送信信号を増幅して出力部から出力する。 (2-2-5) Low Noise Amplifier and Power Amplifier The low noise amplifier 8 is provided in the signal path R2. The low noise amplifier 8 has an input (not shown) and an output (not shown). The input section is connected to the matching circuit 6, and the output section is connected to the signal output terminal 10B. The low noise amplifier 8 amplifies the received signal input to the input section and outputs the amplified signal from the output section. A power amplifier 9 is provided on the signal path R3. The power amplifier 9 has an input (not shown) and an output (not shown). The input section is connected to the signal input terminal 10C. The output section is connected to the matching circuit 7 . The power amplifier 9 amplifies the transmission signal input to the input section and outputs it from the output section.
　（２－２－６）整合回路
　整合回路６は、信号経路Ｒ２に設けられている。整合回路６は、受信フィルタ４とローノイズアンプ８とのインピーダンス整合をとるための回路であり、受信フィルタ４とローノイズアンプ８との間に接続されている。整合回路７は、信号経路Ｒ３に設けられている。整合回路７は、送信フィルタ５とパワーアンプ９とのインピーダンス整合をとるための回路であり、送信フィルタ５とパワーアンプ９との間に接続されている。 (2-2-6) Matching Circuit The matching circuit 6 is provided on the signal path R2. The matching circuit 6 is a circuit for impedance matching between the reception filter 4 and the low noise amplifier 8 and is connected between the reception filter 4 and the low noise amplifier 8 . The matching circuit 7 is provided on the signal path R3. The matching circuit 7 is a circuit for impedance matching between the transmission filter 5 and the power amplifier 9 and is connected between the transmission filter 5 and the power amplifier 9 .
　（２－３）通信装置の動作
　図１を参照して通信装置１００の動作を説明する。受信時は、スイッチ３の共通端子３ａが選択端子３ｂに接続される。これにより、信号経路Ｒ１と信号経路Ｒ２とが接続される。この状態で、アンテナ４０で受信信号が受信されると、受信信号が信号経路Ｒ１，Ｒ２を流れる。そのとき、受信信号は、受信フィルタ４、整合回路６及びローノイズアンプ８を順に通過する。そして、受信信号は、信号出力端子１０Ｂから信号処理回路２０に出力される。送信時は、スイッチ３の共通端子３ａが選択端子３ｃに接続される。これにより、信号経路Ｒ１と信号経路Ｒ３とが接続される。この状態で、信号処理回路２０から信号入力端子１０Ｃに送信信号が入力されると、送信信号が信号経路Ｒ３，Ｒ１を流れる。そのとき、送信信号は、パワーアンプ９、整合回路７及び送信フィルタ５を順に通過する。そして、送信信号は、アンテナ端子１０Ａから出力されてアンテナ４０から送信される。 (2-3) Operation of Communication Apparatus Operation of the communication apparatus 100 will be described with reference to FIG. During reception, the common terminal 3a of the switch 3 is connected to the selection terminal 3b. This connects the signal path R1 and the signal path R2. In this state, when a reception signal is received by the antenna 40, the reception signal flows through the signal paths R1 and R2. At that time, the received signal passes through the receive filter 4, the matching circuit 6 and the low noise amplifier 8 in order. The received signal is then output to the signal processing circuit 20 from the signal output terminal 10B. During transmission, the common terminal 3a of the switch 3 is connected to the selection terminal 3c. This connects the signal path R1 and the signal path R3. In this state, when a transmission signal is input from the signal processing circuit 20 to the signal input terminal 10C, the transmission signal flows through the signal paths R3 and R1. At that time, the transmission signal passes through the power amplifier 9, the matching circuit 7 and the transmission filter 5 in order. Then, the transmission signal is output from the antenna terminal 10A and transmitted from the antenna 40. FIG.
　（３）受信フィルタ及び送信フィルタの構造
　（３－１）全体構成
　受信フィルタ４及び送信フィルタ５は、基本的には互いに同じ構造を有するため、以下の説明では、受信フィルタ４の構造を説明し、送信フィルタ５の構造の説明は省略する。受信フィルタ４は、上述の通り、弾性波フィルタ２によって構成されている。弾性波フィルタ２は、図２及び図３に示すように、圧電性基板４１と、複数（図示例では３つ）のＩＤＴ電極４２と、複数（図示例では４つ）の導電補助部材４３（導電部材）と、複数（図示例では３つ）のビア４４と、複数の外部端子４５と、複数の接合層４６と、周壁４７と、カバー部材４８とを備える。 (3) Structures of Receiving Filter and Transmitting Filter (3-1) Overall Configuration Since the receiving filter 4 and the transmitting filter 5 basically have the same structure as each other, only the structure of the receiving filter 4 will be described below. , the description of the structure of the transmission filter 5 is omitted. The reception filter 4 is composed of the acoustic wave filter 2 as described above. As shown in FIGS. 2 and 3, the acoustic wave filter 2 includes a piezoelectric substrate 41, a plurality of (three in the illustrated example) IDT electrodes 42, and a plurality of (four in the illustrated example) conductive auxiliary members 43 ( conductive member), a plurality of (three in the illustrated example) vias 44 , a plurality of external terminals 45 , a plurality of bonding layers 46 , a peripheral wall 47 , and a cover member 48 .
　圧電性基板４１は、弾性波フィルタ２を構成する部品を実装する基板であり、例えば矩形の板状である。圧電性基板４１は、圧電性基板４１の厚さ方向Ｄ１の少なくとも一部に圧電性を有する基板である。本実施形態では、圧電性基板４１は、厚さ方向Ｄ１の全体に圧電性を有する圧電基板４９である。圧電基板４９は、例えば、タンタル酸リチウム（ＬｉＴａＯ３）又はニオブ酸リチウム（ＬｉＮｂＯ３）で形成されている。圧電性基板４１は、厚さ方向Ｄ１において互いに対向する第１主面４１ａ及び第２主面４１ｂを有する。 The piezoelectric substrate 41 is a substrate on which components constituting the acoustic wave filter 2 are mounted, and has, for example, a rectangular plate shape. The piezoelectric substrate 41 is a substrate having piezoelectricity at least partially in the thickness direction D1 of the piezoelectric substrate 41 . In the present embodiment, the piezoelectric substrate 41 is a piezoelectric substrate 49 having piezoelectricity throughout the thickness direction D1. The piezoelectric substrate 49 is made of, for example, lithium tantalate (LiTaO 3 ) or lithium niobate (LiNbO 3 ). The piezoelectric substrate 41 has a first main surface 41a and a second main surface 41b facing each other in the thickness direction D1.
　ＩＤＴ電極４２は、圧電性基板４１の第１主面４１ａに膜状に設けられている。ＩＤＴ電極４２は、例えば、上層側から順にアルミニウム（Ａｌ）及びチタン（Ｔｉ）が積層されて形成されている。ＩＤＴ電極４２は、一対の櫛型電極４２２を有する。一対の櫛型電極４２２はそれぞれ、複数の電極指４２３とバスバー４２４とを有する。複数の電極指４２３はそれぞれ、圧電性基板４１の厚さ方向Ｄ１からの平面視で例えば帯状である。複数の電極指４２３は、それらの長手方向に直交する方向において互いに間隔を空けて平行に並ぶように配置されている。複数の電極指４２３の各々の一端部は、バスバー４２４に接続されている。バスバー４２４は、複数の電極指４２３に電圧を供給するための配線であり、例えば帯状である。バスバー４２４は、複数の電極指４２３の一端部に接続されている。ＩＤＴ電極４２は、一対の櫛型電極４２２の複数の電極指４２３が噛み合うように配置されている。複数のＩＤＴ電極４２の各々は、圧電性基板４１と共に弾性波共振子を構成している。 The IDT electrode 42 is provided in the form of a film on the first main surface 41a of the piezoelectric substrate 41 . The IDT electrode 42 is formed by laminating aluminum (Al) and titanium (Ti) in order from the upper layer side, for example. The IDT electrode 42 has a pair of comb electrodes 422 . A pair of comb-shaped electrodes 422 each has a plurality of electrode fingers 423 and bus bars 424 . Each of the plurality of electrode fingers 423 has, for example, a strip shape when viewed from the thickness direction D1 of the piezoelectric substrate 41 in plan view. The plurality of electrode fingers 423 are arranged so as to be spaced apart and parallel to each other in the direction orthogonal to their longitudinal direction. One end of each of the plurality of electrode fingers 423 is connected to bus bar 424 . The bus bar 424 is wiring for supplying a voltage to the plurality of electrode fingers 423, and is strip-shaped, for example. The bus bar 424 is connected to one ends of the electrode fingers 423 . The IDT electrodes 42 are arranged such that the plurality of electrode fingers 423 of the pair of comb-shaped electrodes 422 are engaged with each other. Each of the plurality of IDT electrodes 42 constitutes an elastic wave resonator together with the piezoelectric substrate 41 .
　複数の導電補助部材４３はそれぞれ、ＩＤＴ電極４２同士を接続する部材、又は、ＩＤＴ電極４２とビア４４とを接続する部材である。また、各導電補助部材４３は、ドライエッチング及びレーザ加工でビア４４を形成するための貫通孔７０（図５Ｄ参照）を圧電性基板４１に形成するときのストッパ層として機能する部材である。導電補助部材４３は、電気抵抗及びインダクタンスを低減するために、ＩＤＴ電極４２の厚さよりも厚く形成されている。導電補助部材４３は、複数の金属層が積層されて形成されている。例えば、導電補助部材４３は、上層側から順にアルミニウム（Ａｌ）、チタン（Ｔｉ）、白金（Ｐｔ）及びチタンが積層されて形成されている。なお、導電補助部材４３は、上層側から順にアルミニウム及びチタンが積層されて形成されてもよいし、上層側から順にアルミニウム及びクロム（Ｃｒ）が積層されて形成されてもよいし、金（Ａｕ）及びチタンが積層されて形成されてもよい。なお、導電補助部材４３は、単一の金属（例えば金（Ａｕ））で形成されてもよい。 Each of the plurality of conductive auxiliary members 43 is a member that connects the IDT electrodes 42 together or a member that connects the IDT electrodes 42 and the vias 44 . Further, each conductive auxiliary member 43 is a member that functions as a stopper layer when the through hole 70 (see FIG. 5D) for forming the via 44 is formed in the piezoelectric substrate 41 by dry etching and laser processing. The conductive auxiliary member 43 is formed thicker than the IDT electrode 42 in order to reduce electrical resistance and inductance. The conductive auxiliary member 43 is formed by laminating a plurality of metal layers. For example, the conductive auxiliary member 43 is formed by laminating aluminum (Al), titanium (Ti), platinum (Pt), and titanium in this order from the upper layer side. The conductive auxiliary member 43 may be formed by laminating aluminum and titanium in order from the upper layer side, may be formed by laminating aluminum and chromium (Cr) in order from the upper layer side, or may be formed by laminating gold (Au ) and titanium may be laminated. Incidentally, the conductive auxiliary member 43 may be made of a single metal (for example, gold (Au)).
　外部端子４５は、圧電性基板４１の第２主面４１ｂに設けられている。外部端子４５は、弾性波フィルタ２を外部基板（例えば高周波モジュール１の実装基板１１）と電気的に接続するための端子である。外部端子４５は、接合層４６を介してビア４４に接続されている。外部端子４５は、例えば、はんだで形成されたはんだ端子である。 The external terminals 45 are provided on the second main surface 41 b of the piezoelectric substrate 41 . The external terminal 45 is a terminal for electrically connecting the elastic wave filter 2 to an external substrate (for example, the mounting substrate 11 of the high frequency module 1). The external terminal 45 is connected to the via 44 through the bonding layer 46 . The external terminals 45 are, for example, solder terminals made of solder.
　接合層４６は、外部端子４５とビア４４との間に設けられており、外部端子４５とビア４４とを接合する部材である。接合層４６は、例えば金ニッケル合金（ＡｕＮｉ）である。接合層４６は、本実施形態では必須の構成でないため、無くてもよい。この場合、外部端子４５は、ビア４４と直接接続される。 The bonding layer 46 is provided between the external terminal 45 and the via 44 and is a member that bonds the external terminal 45 and the via 44 . The bonding layer 46 is, for example, a gold-nickel alloy (AuNi). Since the bonding layer 46 is not an essential component in this embodiment, it may be omitted. In this case, the external terminal 45 is directly connected to the via 44 .
　ビア４４は、圧電性基板４１において厚さ方向Ｄ１に貫通し、導電補助部材４３と複数の外部端子４５の少なくとも１つとを電気的に接続する部材である。本実施形態では、ビア４４は、上述のように、接合層４６を介して外部端子４５と接続されている。ビア４４は、例えば銅（Ｃｕ）又は銅合金で形成されている。 The via 44 is a member that penetrates through the piezoelectric substrate 41 in the thickness direction D<b>1 and electrically connects the conductive auxiliary member 43 and at least one of the plurality of external terminals 45 . In this embodiment, the via 44 is connected to the external terminal 45 via the bonding layer 46 as described above. The via 44 is made of copper (Cu) or a copper alloy, for example.
　周壁４７は、圧電性基板４１とカバー部材４８との間に配置されることで、圧電性基板４１とカバー部材４８との間にＩＤＴ電極４２及び導電補助部材４３を収容する収容空間ＳＰ１を確保する部材（例えばスペーサ）である。周壁４７は、例えば枠状であり、圧電性基板４１の第１主面４１ａにおいて、ＩＤＴ電極４２及び導電補助部材４３を囲むように配置されている。周壁４７は、例えば、ポリイミド、エポキシ樹脂又はシリコン（Ｓｉ）で形成されている。 The peripheral wall 47 is arranged between the piezoelectric substrate 41 and the cover member 48 to secure an accommodation space SP1 for accommodating the IDT electrode 42 and the conductive auxiliary member 43 between the piezoelectric substrate 41 and the cover member 48. It is a member (for example, a spacer) that The peripheral wall 47 has a frame shape, for example, and is arranged on the first main surface 41 a of the piezoelectric substrate 41 so as to surround the IDT electrode 42 and the conductive auxiliary member 43 . The peripheral wall 47 is made of, for example, polyimide, epoxy resin, or silicon (Si).
　カバー部材４８は、周壁４７における第１主面４１ａ側とは反対側の開口を覆う部材である。カバー部材４８は、周壁４７の第１主面４１ａ側とは反対側の端部に設けられている。カバー部材４８は、例えば平板状である。カバー部材４８は、例えばポリイミド、エポキシ樹脂又はシリコン（Ｓｉ）で形成されている。 The cover member 48 is a member that covers the opening of the peripheral wall 47 on the side opposite to the first main surface 41a side. The cover member 48 is provided at the end of the peripheral wall 47 opposite to the first principal surface 41a. The cover member 48 has, for example, a flat plate shape. The cover member 48 is made of polyimide, epoxy resin, or silicon (Si), for example.
　（３－２）ビアの構造の詳細
　図４を参照してビア４４の構造の詳細について説明する。図４は、図３の部分拡大図であって、圧電性基板４１を所定の断面で切ったときの断面図である。所定の断面とは、例えば、圧電性基板４１の第２主面４１ｂに直交しかつビア４４（より詳細にはビア４４の頂面（第１主面４１ａ側の面）の中心）を含む断面である。 (3-2) Details of Via Structure Details of the structure of the via 44 will be described with reference to FIG. FIG. 4 is a partially enlarged view of FIG. 3, and is a cross-sectional view when the piezoelectric substrate 41 is cut along a predetermined cross section. The predetermined cross section is, for example, a cross section perpendicular to the second main surface 41b of the piezoelectric substrate 41 and including the via 44 (more specifically, the center of the top surface of the via 44 (the surface on the first main surface 41a side)). is.
　ビア４４は、圧電性基板４１の第２主面４１ｂ側（すなわち外部端子４５側）から第１主面４１ａ側（すなわち導電補助部材４３側）に向かって幅が漸次小さくなる柱形である。ビア４４は、第１柱部４４１と第２柱部４４２とを有する。 The via 44 has a columnar shape whose width gradually decreases from the second main surface 41b side (that is, the external terminal 45 side) of the piezoelectric substrate 41 toward the first main surface 41a side (that is, the conductive auxiliary member 43 side). The via 44 has a first columnar portion 441 and a second columnar portion 442 .
　第１柱部４４１は、高さＴ１を有する柱状の部分である。高さＴ１は、圧電性基板４１の第２主面４１ｂから圧電性基板４１の厚さ方向Ｄ１の途中までの高さである。換言すれば、高さＴ１は、圧電性基板４１の第２主面４１ｂから第１主面４１ａと第２主面４１ｂとの間の位置までの高さである。高さＴ１は、例えば、圧電性基板４１の厚さの２分の１よりも大きくてもよいし、望ましくは、圧電性基板４１の厚さの３分の２よりも大きくてもよいし、更に望ましくは、圧電性基板４１の厚さの４分の３よりも大きくてもよい。第１柱部４４１は、例えば円錐台形であり、第１柱部４４１の直径は、圧電性基板４１の第２主面４１ｂ側から第１主面４１ａ側に向かって漸次小さくなっている。したがって、第１柱部４４１の外周面４４１ａは、第１柱部４４１の底面４４１ｂ（第２主面４１ｂ側の面、第１面）から頂面４４１ｃ（第１主面４１ａ側の面、第２面）に向かって、第１柱部４４１の内側に傾斜している。 The first columnar portion 441 is a columnar portion having a height T1. The height T1 is the height from the second main surface 41b of the piezoelectric substrate 41 to the middle of the piezoelectric substrate 41 in the thickness direction D1. In other words, the height T1 is the height from the second principal surface 41b of the piezoelectric substrate 41 to a position between the first principal surface 41a and the second principal surface 41b. The height T1 may be, for example, more than half the thickness of the piezoelectric substrate 41, preferably more than two-thirds the thickness of the piezoelectric substrate 41, More preferably, it may be greater than three quarters of the thickness of the piezoelectric substrate 41 . The first columnar portion 441 has, for example, a truncated cone shape, and the diameter of the first columnar portion 441 gradually decreases from the second main surface 41b side of the piezoelectric substrate 41 toward the first main surface 41a side. Therefore, the outer peripheral surface 441a of the first columnar portion 441 extends from the bottom surface 441b (the surface on the second main surface 41b side, the first surface) of the first columnar portion 441 to the top surface 441c (the surface on the first main surface 41a side, the first surface). 2 surface), and is inclined inwardly of the first column portion 441 .
　第２柱部４４２は、高さＴ２を有する柱状の部分である。高さＴ２は、第１柱部４４１の頂面から圧電性基板４１の第１主面４１ａまでの高さである。第２柱部４４２の底面４４２ｂ（第２主面４１ｂ側の面）の全体は、第１柱部４４１の頂面４４１ｃの全体に重なっている。第２柱部４４２は、例えば円錐台形であり、第２柱部４４２の直径は、圧電性基板４１の第２主面４１ｂ側から第１主面４１ａ側に向けって漸次小さくなっている。したがって、第２柱部４４２の外周面４４２ａは、第２柱部４４２の底面４４２ｂ（第２主面４１ｂ側の面、第１面）から頂面４４２ｃ（第１主面４１ａ側の面、第２面）に向かって、第２柱部４４２の内側に傾斜している。第２柱部４４２の外周面４４２ａの傾斜は、第１柱部４４１の外周面４４１ａの傾斜よりも急傾斜である。 The second columnar portion 442 is a columnar portion having a height T2. A height T2 is the height from the top surface of the first columnar portion 441 to the first main surface 41a of the piezoelectric substrate 41 . The entire bottom surface 442 b (the surface on the second main surface 41 b side) of the second columnar portion 442 overlaps the entire top surface 441 c of the first columnar portion 441 . The second columnar portion 442 has, for example, a truncated cone shape, and the diameter of the second columnar portion 442 gradually decreases from the second main surface 41b side of the piezoelectric substrate 41 toward the first main surface 41a side. Therefore, the outer peripheral surface 442a of the second columnar portion 442 extends from the bottom surface 442b (the surface on the side of the second main surface 41b, the first surface) of the second columnar portion 442 to the top surface 442c (the surface on the side of the first main surface 41a, the surface on the side of the first main surface 41a). 2), and is inclined inwardly of the second column portion 442 . The inclination of the outer peripheral surface 442 a of the second columnar portion 442 is steeper than the inclination of the outer peripheral surface 441 a of the first columnar portion 441 .
　より詳細には、図４に示すように、圧電性基板４１の上述の断面（第２主面４１ｂに直交しかつビア４４を含む断面）での断面視において、ビア４４は、左右の側辺４４ａ，４４ｂを有する。側辺４４ａ，４４ｂは、ビア４４の外周面４４ｃにおける上述の断面との交差部分である。ビア４４の側辺４４ａと圧電性基板４１の第１主面４１ａとの交点を第１交点Ｐ１とし、ビア４４の側辺４４ａと圧電性基板４１の第２主面４１ｂとの交点を第２交点Ｐ２とし、ビア４４の側辺４４ａにおいて側辺４４ａの傾斜が変化する点を変化点Ｐ３とする。変化点Ｐ３は、上記の断面での断面視において、ビア４４の外周面４４ｃにおいて外周面４４ｃの傾斜が変化する点である。上記の断面での断面視における外周面４４ｃの傾斜とは、上記の断面においてビア４４の外周面４４ｃと交わる部分の傾斜である。第１交点Ｐ１、第２交点Ｐ２及び変化点Ｐ３は、上記の断面での断面視において、圧電性基板４１の第２主面４１ｂに平行な方向において、ビア４４における互いに同じ側（例えば図４では右側）にある。また、変化点Ｐ３と第２交点Ｐ２とを結ぶ線分を第１線分Ｈ１とし、変化点Ｐ３と第１交点Ｐ１とを結ぶ線分を第２線分Ｈ２とする。また、上記の断面視で第１線分Ｈ１と圧電性基板４１の第２主面４１ｂとが成す鋭角を第１角αとし、上記の断面視で第２線分Ｈ２と仮想線Ｌ１とが成す鋭角を第２角βとする。仮想線Ｌ１は、変化点Ｐ３を通って第２主面４１ｂに平行な線である。このとき、第２角βは、第１角αよりも大きい。換言すれば、第２柱部４４２の外周面４４２ａの傾斜は、第１柱部４４１の外周面４４２ａの傾斜よりも急傾斜である。 More specifically, as shown in FIG. 4, in a cross-sectional view of the above-described cross section of the piezoelectric substrate 41 (a cross section orthogonal to the second main surface 41b and including the vias 44), the vias 44 are formed along the left and right side edges. 44a and 44b. The side edges 44a and 44b are the crossing portions of the outer peripheral surface 44c of the via 44 and the cross section described above. The intersection of the side 44a of the via 44 and the first main surface 41a of the piezoelectric substrate 41 is defined as a first intersection P1, and the intersection of the side 44a of the via 44 and the second main surface 41b of the piezoelectric substrate 41 is defined as a second intersection. The point at which the slope of the side 44a of the via 44 changes is the point of change P3. The change point P3 is a point at which the inclination of the outer peripheral surface 44c of the via 44 changes in the cross-sectional view of the cross section. The inclination of the outer peripheral surface 44c in the cross-sectional view of the cross section is the inclination of the portion that intersects with the outer peripheral surface 44c of the via 44 in the cross section. The first intersection point P1, the second intersection point P2, and the change point P3 are located on the same side of the via 44 in the direction parallel to the second main surface 41b of the piezoelectric substrate 41 (for example, in FIG. on the right). A line segment connecting the change point P3 and the second intersection point P2 is defined as a first line segment H1, and a line segment connecting the change point P3 and the first intersection point P1 is defined as a second line segment H2. Further, the acute angle formed by the first line segment H1 and the second main surface 41b of the piezoelectric substrate 41 in the above cross-sectional view is defined as a first angle α, and the second line segment H2 and the virtual line L1 in the above cross-sectional view are formed. Let the acute angle to form be the second angle β. The virtual line L1 is a line parallel to the second main surface 41b passing through the point of change P3. At this time, the second angle β is larger than the first angle α. In other words, the inclination of the outer peripheral surface 442 a of the second pillar 442 is steeper than the inclination of the outer peripheral surface 442 a of the first pillar 441 .
　このように、第２角βが第１角αよりも大きいため、第２角βが第１角αと同じである場合と比べて、上述の断面視において、第２柱部４４２の頂面４４２ｃの幅（すなわち第１主面４１ａでのビア４４の幅）Ｗ１を大きくすることができる。これにより、ビア４４と導電補助部材４３との接触面積を比較的大きくすることができる。この結果、ビア４４と導電補助部材４３との接続信頼性を向上できる。かつ、ビア４４と導電補助部材４３との接触部分での電気抵抗及びインダクタンスを低減でき、これによりフィルタ特性の劣化を抑制できる。 In this way, since the second angle β is larger than the first angle α, the top surface of the second columnar portion 442 in the cross-sectional view described above is larger than the case where the second angle β is the same as the first angle α. The width W1 of 442c (that is, the width of via 44 on first main surface 41a) can be increased. Thereby, the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large. As a result, connection reliability between the via 44 and the conductive auxiliary member 43 can be improved. Moreover, the electrical resistance and inductance at the contact portion between the via 44 and the conductive auxiliary member 43 can be reduced, thereby suppressing deterioration of filter characteristics.
　（３－３）弾性波フィルタの製造方法
　図５Ａ～図６Ｃを参照して弾性波フィルタ２の製造方法を説明する。 (3-3) Method for Manufacturing Elastic Wave Filter A method for manufacturing the elastic wave filter 2 will be described with reference to FIGS. 5A to 6C.
　図５Ａに示すように、圧電性基板４１として用いられる基板４１０の第１主面４１０ａにＩＤＴ電極４２及び導電補助部材４３を形成する。より詳細には、まず、例えば蒸着又はスパッタリングによって、基板４１０の第１主面４１０ａにおいて、ＩＤＴ電極４２として用いられる金属膜を形成する。金属膜は、例えばアルミニウム（Ａｌ）及びチタン（Ｔｉ）がこの順に上層側から積層された膜である。そして、フォトリソグラフィプロセスによって、形成した金属膜を所定の形状に形成することでＩＤＴ電極４２を形成する。そして、ＩＤＴ電極４２の製造手順と同様の製造手順で、導電補助部材４３を形成する。導電補助部材４３は、例えばアルミニウム、チタン、白金（Ｐｔ）及びチタンがこの順に上層側から積層された膜である。導電補助部材４３は、ＩＤＴ電極４２と接続されている。導電補助部材４３の最下層（チタン層）は、後述のように、レーザ加工及びドライエッチングによって基板４１０に孔を空けるときのストッパ層として機能する。このように、第１主面４１０ａにおいてＩＤＴ電極４２及びＩＤＴ電極４２に接続された導電補助部材４３が配置された基板４１０が用意される。 As shown in FIG. 5A, the IDT electrode 42 and the conductive auxiliary member 43 are formed on the first main surface 410a of the substrate 410 used as the piezoelectric substrate 41. As shown in FIG. More specifically, first, a metal film to be used as the IDT electrode 42 is formed on the first main surface 410a of the substrate 410 by vapor deposition or sputtering, for example. The metal film is, for example, a film in which aluminum (Al) and titanium (Ti) are laminated in this order from the upper layer side. Then, the IDT electrode 42 is formed by forming the formed metal film into a predetermined shape by a photolithography process. Then, the conductive auxiliary member 43 is formed by the same manufacturing procedure as that of the IDT electrode 42 . The conductive auxiliary member 43 is a film in which, for example, aluminum, titanium, platinum (Pt), and titanium are laminated in this order from the upper layer side. The conductive auxiliary member 43 is connected to the IDT electrode 42 . The bottom layer (titanium layer) of the conductive auxiliary member 43 functions as a stopper layer when a hole is made in the substrate 410 by laser processing and dry etching, as will be described later. Thus, the substrate 410 on which the IDT electrodes 42 and the conductive auxiliary members 43 connected to the IDT electrodes 42 are arranged on the first main surface 410a is prepared.
　次に図５Ｂに示すように、基板４１０の第１主面４１０ａにおいて、周壁４７及びカバー部材４８を形成する。より詳細には、まず、周壁４７として用いられる層（例えばポリイミド層）を基板４１０の第１主面４１０ａの全面に形成し、形成した層をフォトリソグラフィプロセスによって所定の形状に形成する。これにより、周壁４７が形成される。そして、カバー部材４８として用いられる部材（例えばエポキシ樹脂シート）を周壁４７の頂部側（第１主面４１ａとは反対側）の開口を塞ぐように周壁４７の頂部（第１主面４１ａ側とは反対側の端部）に圧着する。これにより、周壁４７の頂部にカバー部材４８が設けられる。 Next, as shown in FIG. 5B, on the first main surface 410a of the substrate 410, the peripheral wall 47 and the cover member 48 are formed. More specifically, first, a layer (for example, a polyimide layer) used as the peripheral wall 47 is formed over the entire first main surface 410a of the substrate 410, and the formed layer is formed into a predetermined shape by a photolithography process. Thereby, the peripheral wall 47 is formed. Then, a member (for example, an epoxy resin sheet) used as the cover member 48 is placed on the top portion of the peripheral wall 47 (on the side opposite to the first main surface 41a) so as to close the opening on the top portion side of the peripheral wall 47 (on the side opposite to the first main surface 41a). the opposite end). Thereby, the cover member 48 is provided on the top of the peripheral wall 47 .
　次に図５Ｃ及び図５Ｄに示すように、基板４１０においてビア４４を設けるための貫通孔７０を形成する。より詳細には、まず、図５Ｃに示すように、レーザ加工によって、基板４１０の第２主面４１０ｂにおいて、所定の位置に所定の深さＫ１の穴部６０を形成する。穴部６０の深さＫ１は、基板４１０の第２主面４１０ｂから基板４１０の厚さ方向Ｄ１の途中までの深さである。換言すれば、穴部６０の深さＫ１は、基板４１０の第２主面４１０ｂから基板４１０の第１主面４１０ａと第２主面４１０ｂとの間の位置までの深さである。穴部６０の深さＫ１は、例えば基板４１０の厚さの２分の１以上の深さである。深さＫ１は、ビア４４の第１柱部４４１の高さＴ１と同じ高さである。このとき、レーザ加工は、導電補助部材４３をストッパ層として実行されるが、穴部６０の底面６０ａと導電補助部材４３との間隔Ｋ２は、レーザ光の熱によって導電補助部材４３が破損しない程度に極力小さい間隔にすることが望ましい。これにより、レーザ加工で、穴部６０を極力深く掘りつつレーザの熱による導電補助部材４３の破損を防止できる。 Next, as shown in FIGS. 5C and 5D, through holes 70 for providing vias 44 are formed in the substrate 410 . More specifically, first, as shown in FIG. 5C, a hole 60 having a predetermined depth K1 is formed at a predetermined position in the second main surface 410b of the substrate 410 by laser processing. The depth K1 of the hole portion 60 is the depth from the second main surface 410b of the substrate 410 to the middle of the substrate 410 in the thickness direction D1. In other words, depth K1 of hole 60 is the depth from second main surface 410b of substrate 410 to a position between first main surface 410a and second main surface 410b of substrate 410 . The depth K1 of the hole 60 is, for example, half or more the thickness of the substrate 410 . The depth K1 is the same height as the height T1 of the first columnar portion 441 of the via 44 . At this time, the laser processing is performed using the auxiliary conductive member 43 as a stopper layer. It is desirable to make the interval as small as possible. This makes it possible to dig the hole 60 as deeply as possible and prevent damage to the conductive auxiliary member 43 due to laser heat.
　一般にレーザ加工で基板４１０に穴部６０を形成するとき、レーザの出力は、穴部６０が掘り進まれるに連れて弱くなるように制御される。このため、穴部６０の直径（幅）Ｗ２は、第２主面４１０ｂ側から第１主面４１０ａ側に行くほど小さくなる。すなわち、穴部６０の内周面６０ｂは、第２主面４１０ｂ側から第１主面４１０ａに向かって穴部６０の内側に傾斜する。 Generally, when forming the hole 60 in the substrate 410 by laser processing, the output of the laser is controlled so as to weaken as the hole 60 is dug. Therefore, the diameter (width) W2 of the hole portion 60 decreases from the second main surface 410b side to the first main surface 410a side. That is, the inner peripheral surface 60b of the hole portion 60 is inclined inwardly of the hole portion 60 from the second main surface 410b side toward the first main surface 410a.
　次に図５Ｄに示すように、ドライエッチングによって、穴部６０の底面６０ａにおいて基板４１０の第１主面４１０ａまで貫通する貫通孔６１を形成する。すなわち、ドライエッチングによって、穴部６０の底面６０ａと第１主面４１ａとの間を貫通させる。これにより、圧電性基板４１を貫通する貫通孔７０が形成される。貫通孔７０は、穴部６０と貫通孔６１とで構成されている。このとき、ドライエッチングは、導電補助部材４３をストッパ層として実行されるため、第１主面４１ａでの貫通孔７０の開口から導電補助部材４３が露出している。このように基板４１０に貫通孔７０が形成されることで、貫通孔７０を有する圧電性基板４１が形成される。 Next, as shown in FIG. 5D, a through hole 61 is formed through the bottom surface 60a of the hole 60 to the first main surface 410a of the substrate 410 by dry etching. That is, dry etching is used to penetrate between the bottom surface 60a of the hole 60 and the first main surface 41a. Thereby, a through hole 70 penetrating through the piezoelectric substrate 41 is formed. The through hole 70 is composed of the hole portion 60 and the through hole 61 . At this time, since the dry etching is performed using the auxiliary conductive member 43 as a stopper layer, the auxiliary conductive member 43 is exposed from the opening of the through hole 70 in the first main surface 41a. By forming the through holes 70 in the substrate 410 in this manner, the piezoelectric substrate 41 having the through holes 70 is formed.
　より詳細には、ドライエッチングでは、マスクを用いずに、基板４１０の第２主面４１０ｂ側の表面全体（特に図５Ｄの表面部分Ｑ１，Ｑ２）を削ることで、穴部６０の底面６０ａと基板４１０の第１主面４１０ａとの間を貫通させる。表面部分Ｑ１は、基板４１０の第２主面４１０ｂを含む部分であり、表面部分Ｑ２は、穴部６０の底面６０ａと基板４１０の第１主面４１ａとの間の部分である。このドライエッチングでは、基板４１０には穴部６０が既に形成されているので、マスクを用いなくても、穴部６０の底面６０ａを選択的に貫通させることが可能である。 More specifically, in dry etching, without using a mask, the entire surface of the substrate 410 on the second main surface 410b side (particularly the surface portions Q1 and Q2 in FIG. It penetrates between the first major surface 410 a of the substrate 410 . Surface portion Q1 is a portion including second main surface 410b of substrate 410, and surface portion Q2 is a portion between bottom surface 60a of hole 60 and first main surface 41a of substrate 410. FIG. Since the holes 60 are already formed in the substrate 410 in this dry etching, the bottom surfaces 60a of the holes 60 can be selectively penetrated without using a mask.
　また、このドライエッチングでは、表面部分Ｑ１，Ｑ２以外に、穴部６０の内周面６０ｂも或る程度削られる。穴部６０の内周面６０ｂは、レーザ加工によって若干荒れていたり、レーザ加工による焦げカスが付着していたりする場合があるが、このドライエッチングによって穴部６０の内周面６０ｂが滑らかに加工されかつ上記の焦げカスが削りとられる。つまり、この製造方法では、穴部６０の底面６０ａを貫通させるための製造工程（ドライエッチング）が、穴部６０の内周面６０ｂを滑らかに整えるための製造工程を兼用している。 In this dry etching, the inner peripheral surface 60b of the hole 60 is also etched to some extent in addition to the surface portions Q1 and Q2. The inner peripheral surface 60b of the hole 60 may be slightly roughened by laser processing, or may have burnt residue due to laser processing, but the inner peripheral surface 60b of the hole 60 is processed smoothly by this dry etching. And the burnt residue is scraped off. That is, in this manufacturing method, the manufacturing process (dry etching) for penetrating the bottom surface 60a of the hole 60 also serves as the manufacturing process for smoothing the inner peripheral surface 60b of the hole 60. FIG.
　また、このドライエッチングは、貫通孔６１の第１主面４１ａでの直径Ｗ３が所定の幅に達するまで所定時間（十分な時間）行われる。この結果、貫通孔６１の内周面６１ｂは第２主面４１ｂ側から第１主面４１ａ側に向かって貫通孔６１の内側に傾斜するが、貫通孔６１の内周面６１ｂの傾斜は、穴部６０の内周面６０ｂの傾斜よりも急傾斜になる。これにより、貫通孔７０の内周面７０ｂは、穴部６０の内周面６０ｂと貫通孔６１の内周面６１ｂとの境界で傾斜が変化する。この境界が上記の変化点Ｐ３に対応する。 Also, this dry etching is performed for a predetermined time (sufficient time) until the diameter W3 of the through hole 61 at the first main surface 41a reaches a predetermined width. As a result, the inner peripheral surface 61b of the through-hole 61 is inclined inwardly from the second main surface 41b toward the first main surface 41a. The inclination is steeper than the inclination of the inner peripheral surface 60 b of the hole portion 60 . Accordingly, the inclination of the inner peripheral surface 70 b of the through hole 70 changes at the boundary between the inner peripheral surface 60 b of the hole portion 60 and the inner peripheral surface 61 b of the through hole 61 . This boundary corresponds to the change point P3.
　次に図６Ａに示すように、金属（例えば銅）によって、圧電性基板４１の貫通孔７０の内部において、導電補助部材４３と接続するビア４４を形成する。これにより、例えば銅製のビア４４が形成される。なお、貫通孔７０の内部とは、貫通孔７０の内側の空間であって、貫通孔７０の両側の開口面の間の空間である。図６Ａの例では、ビア４４の頂面（すなわち第２柱部４４２の頂面）４４２ｃ全体が導電補助部材４３と接続する。ビア４４は、貫通孔７０の内部に金属が充填されることで形成されるため、ビア４４の形状は、貫通孔７０の内部の形状と同じ形状である。したがって、ビア４４の外周面４４ｃの傾斜は、穴部６０と貫通孔６１との境界（変化点Ｐ３）で変化する。すなわち上述の断面視において、ビア４４の側辺４４ａにおいて、貫通孔６１に対応する線分Ｈ２の傾斜は、穴部６０に対応する線分Ｈ１の傾斜よりも急傾斜になる。 Next, as shown in FIG. 6A, metal (for example, copper) is used to form vias 44 connected to the conductive auxiliary members 43 inside the through holes 70 of the piezoelectric substrate 41 . As a result, vias 44 made of copper, for example, are formed. The inside of the through-hole 70 is the space inside the through-hole 70 and the space between the open surfaces on both sides of the through-hole 70 . 6A, the entire top surface 442c of the via 44 (that is, the top surface of the second columnar portion 442) is connected to the conductive auxiliary member 43. In the example of FIG. Since the via 44 is formed by filling the inside of the through hole 70 with metal, the shape of the via 44 is the same as the shape of the inside of the through hole 70 . Therefore, the inclination of the outer peripheral surface 44c of the via 44 changes at the boundary between the hole portion 60 and the through hole 61 (change point P3). That is, in the cross-sectional view described above, the slope of the line segment H2 corresponding to the through hole 61 is steeper than the slope of the line segment H1 corresponding to the hole 60 on the side 44a of the via 44 .
　次に図６Ｂに示すように、金属（例えば金ニッケル合金）によって、圧電性基板４１の第２主面４１ｂにおいてビア４４の底面と接続するように接合層４６を形成する。これにより、例えば金ニッケル合金製の接合層４６が形成される。そして、図６Ｃに示すように、外部端子４５（例えばはんだバンプ）が形成される。このように、弾性波フィルタ２が製造される。 Next, as shown in FIG. 6B, a bonding layer 46 is formed from a metal (for example, a gold-nickel alloy) so as to be connected to the bottom surface of the via 44 on the second main surface 41b of the piezoelectric substrate 41 . As a result, a bonding layer 46 made of, for example, a gold-nickel alloy is formed. Then, as shown in FIG. 6C, external terminals 45 (for example, solder bumps) are formed. Thus, the elastic wave filter 2 is manufactured.
　本実施形態では、圧電性基板４１は、厚さ方向Ｄ１の全体がタンタル酸リチウム又はニオブ酸リチウムで形成されている。このような材質の圧電性基板４１に対してレーザ加工だけで貫通孔７０を形成する場合、比較的短時間で貫通孔７０を形成可能であるが、レーザの熱によってストッパ層である導電補助部材４３が破損する可能性がある。他方、上記のような材質の圧電性基板４１に対してドライエッチングだけで貫通孔７０を形成する場合、ストッパ層である導電補助部材４３が破損する可能性は低いが、加工が困難で貫通孔７０を形成するのに時間が掛かる。この事情を鑑みて、本実施形態では、上述のように、レーザ加工とドライエッチングの両方を用いて、圧電性基板４１に貫通孔７０を形成する。すなわち、レーザ加工によって比較的短時間で、圧電性基板４１に対して或る程度の深さＫ１まで（例えば導電補助部材４３の近くまで）穴部６０を形成し、そこから先は、ドライエッチングによって、導電補助部材４３を破損しないように貫通孔６１を形成する。これにより、比較的短時間で導電補助部材４３を破損しないように貫通孔７０が形成される。 In the present embodiment, the piezoelectric substrate 41 is entirely made of lithium tantalate or lithium niobate in the thickness direction D1. When the through hole 70 is formed in the piezoelectric substrate 41 made of such a material only by laser processing, the through hole 70 can be formed in a relatively short time. 43 may be damaged. On the other hand, when the through-holes 70 are formed only by dry etching in the piezoelectric substrate 41 made of the above materials, the possibility of damaging the electrically conductive auxiliary member 43 as a stopper layer is low, but the processing is difficult and the through-holes can be formed. It takes time to form 70. In view of this situation, in the present embodiment, as described above, the through holes 70 are formed in the piezoelectric substrate 41 using both laser processing and dry etching. That is, the holes 60 are formed in the piezoelectric substrate 41 to a certain depth K1 (for example, to the vicinity of the conductive auxiliary member 43) in a relatively short period of time by laser processing, and dry etching is performed thereafter. to form the through hole 61 so as not to damage the conductive auxiliary member 43 . As a result, the through hole 70 is formed in a relatively short time so as not to damage the conductive auxiliary member 43 .
　また、本実施形態では、上記のようにレーザ加工とドライエッチングの両方を用いるため、レーザ加工時のレーザが電補助部材４３に直接当たることを防止できる。すなわち、仮にレーザが導電補助部材４３に当たると、レーザの熱によって導電補助部材４３が変形して、導電補助部材４３と圧電基板４１との間に剥離が生じる場合がある。しかし、本実施形態では、上述のようにレーザ加工とドライエッジングの両方を用いるため、レーザが導電補助部材４３に直接当たることを防止できる。この結果、レーザの熱による上記の剥離を抑制することができる。 In addition, in this embodiment, since both laser processing and dry etching are used as described above, it is possible to prevent the laser during laser processing from directly hitting the electrical auxiliary member 43 . That is, if the laser hits the auxiliary conductive member 43 , the auxiliary conductive member 43 may be deformed by the heat of the laser, and peeling may occur between the auxiliary conductive member 43 and the piezoelectric substrate 41 . However, in this embodiment, since both laser processing and dry edging are used as described above, it is possible to prevent the laser from directly hitting the conductive auxiliary member 43 . As a result, the peeling caused by the heat of the laser can be suppressed.
　（４）主要な効果
　以上、実施形態に係る弾性波フィルタ２は、圧電性基板４１と、ＩＤＴ電極４２（機能電極）と、導電補助部材４３と、外部端子４５と、ビア４４と、を備える。圧電性基板４１は、互いに対向する第１主面４１ａ及び第２主面４１ｂを有する。圧電性基板４１は、厚さ方向Ｄ１の少なくとも一部に圧電性を有する。ＩＤＴ電極４２は、圧電性基板４１の第１主面４１ａに配置されている。導電補助部材４３（補助部材）は、圧電性基板４１の第１主面４１ａに配置されており、ＩＤＴ電極４２に接続されている。外部端子４５は、圧電性基板４１の第２主面４１ｂに配置されている。ビア４４は、圧電性基板４１を厚さ方向Ｄ１に貫通し、外部端子４５と導電補助部材４３とを接続する。圧電性基板４１の第２主面４１ｂに直交する断面での断面視において、ビア４４と圧電性基板４１の第１主面４１ａ及び第２主面４１ｂとの交点をそれぞれ第１交点Ｐ１及び第２交点Ｐ２とし、ビア４４の外周面４４ｃにおいて外周面４４ｃの傾斜が変化する点を変化点Ｐ３とし、第１交点Ｐ１、第２交点Ｐ２及び変化点Ｐ３は、圧電性基板４の第２主面４１ｂに平行な方向においてビア４４における互いに同じ側にある。変化点Ｐ３と第２交点Ｐ２とを結ぶ第１線分Ｈ１と圧電性基板４１の第２主面４１ｂとが成す鋭角を第１角αとし、変化点Ｐ３と第１交点Ｐ１とを結ぶ第２線分Ｈ２と仮想線Ｌ１とが成す鋭角を第２角βとする。仮想線Ｌ１は、変化点Ｐ３を通って圧電性基板４１の第２主面４１ｂに平行である。第２角βは、第１角αよりも大きい。 (4) Main Effects As described above, the acoustic wave filter 2 according to the embodiment includes the piezoelectric substrate 41, the IDT electrodes 42 (functional electrodes), the conductive auxiliary members 43, the external terminals 45, and the vias 44. . The piezoelectric substrate 41 has a first major surface 41a and a second major surface 41b facing each other. The piezoelectric substrate 41 has piezoelectricity at least partially in the thickness direction D1. The IDT electrode 42 is arranged on the first main surface 41 a of the piezoelectric substrate 41 . The conductive auxiliary member 43 (auxiliary member) is arranged on the first main surface 41 a of the piezoelectric substrate 41 and connected to the IDT electrode 42 . The external terminals 45 are arranged on the second main surface 41 b of the piezoelectric substrate 41 . The via 44 penetrates the piezoelectric substrate 41 in the thickness direction D<b>1 and connects the external terminal 45 and the conductive auxiliary member 43 . In a cross-sectional view of a cross section orthogonal to the second main surface 41b of the piezoelectric substrate 41, intersections between the vias 44 and the first main surface 41a and the second main surface 41b of the piezoelectric substrate 41 are designated as a first intersection point P1 and a second main surface 41b, respectively. The point where the inclination of the outer peripheral surface 44c changes on the outer peripheral surface 44c of the via 44 is a change point P3. They are on the same side of the via 44 in the direction parallel to the surface 41b. An acute angle formed by a first line segment H1 connecting the change point P3 and the second intersection point P2 and the second main surface 41b of the piezoelectric substrate 41 is defined as a first angle α, and an acute angle connecting the change point P3 and the first intersection point P1 is defined as a first angle α. The acute angle formed by the two line segments H2 and the virtual line L1 is defined as a second angle β. The virtual line L1 is parallel to the second main surface 41b of the piezoelectric substrate 41 through the change point P3. The second angle β is greater than the first angle α.
　この構成によれば、第２角βが第１角αよりも大きいため、第２角βと第１角αとが同じ大きさである場合と比べて、上記の断面視における圧電性基板４１の第１主面４１ａでのビア４４の幅Ｗ１を大きくすることができる。これにより、ビア４４と導電補助部材４３との接触面積を比較的大きくすることができる。この結果、ビア４４と導電補助部材４３との接続信頼性を向上できる。かつ、ビア４４と導電補助部材４３との接触部分での電気抵抗及びインダクタンスを低減でき、これによりフィルタ特性の劣化を抑制できる。 According to this configuration, the second angle β is larger than the first angle α. The width W1 of the via 44 at the first main surface 41a of can be increased. Thereby, the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large. As a result, connection reliability between the via 44 and the conductive auxiliary member 43 can be improved. Moreover, the electrical resistance and inductance at the contact portion between the via 44 and the conductive auxiliary member 43 can be reduced, thereby suppressing deterioration of filter characteristics.
　（５）変形例
　上記の実施形態の変形例について説明する。以下の説明では、上記の実施形態と同じ構成要素には同じ符号を付して説明を省略し、上記の実施形態と異なる部分を中心に説明する。なお、上記の実施形態及び後述の変形例１―３の組み合わせを実施してもよい。 (5) Modification A modification of the above embodiment will be described. In the following description, the same reference numerals are given to the same components as in the above embodiment, and the description is omitted, and the description will focus on the parts that differ from the above embodiment. Note that a combination of the above-described embodiment and modified examples 1 to 3 described below may be implemented.
　（５－１）変形例１
　上記の実施形態では、圧電性基板４１が厚さ方向Ｄ１の全体に圧電性を有する場合を例示するが、本変形例では、圧電性基板４１が厚さ方向Ｄ１の一部に圧電性を有する場合を例示する。図７に示すように、本変形例では、圧電性基板４１は、圧電体層４１１と支持基板４１２とを備える。支持基板４１２は、圧電体層４１１を支持する基板であり、例えば、シリコン（Ｓｉ）で形成されたシリコン基板である。圧電体層４１１は、圧電性を有する部分であり、例えばタンタル酸リチウム（ＬｉＴａＯ３）又はニオブ酸リチウム（ＬｉＮｂＯ３）で形成されている。圧電体層４１１の厚さｄ１は、支持基板４１２の厚さｄ２よりも小さい。圧電体層４１１の厚さｄ１と支持基板４１２の厚さｄ２の比は、例えば１対９である。圧電体層４１１は、支持基板４１２の片面の全体に形成されている。圧電体層４１１における支持基板４１２側とは反対側の主面には、ＩＤＴ電極４２、導電補助部材４３、周壁４７及びカバー部材４８が設けられている。 (5-1) Modification 1
In the above embodiment, the piezoelectric substrate 41 has piezoelectricity in the entire thickness direction D1, but in this modified example, the piezoelectric substrate 41 has piezoelectricity in part in the thickness direction D1. Illustrate the case. As shown in FIG. 7 , in this modification, the piezoelectric substrate 41 includes a piezoelectric layer 411 and a support substrate 412 . The support substrate 412 is a substrate that supports the piezoelectric layer 411, and is, for example, a silicon substrate made of silicon (Si). The piezoelectric layer 411 is a portion having piezoelectric properties, and is made of, for example, lithium tantalate (LiTaO 3 ) or lithium niobate (LiNbO 3 ). The thickness d1 of the piezoelectric layer 411 is smaller than the thickness d2 of the support substrate 412. As shown in FIG. A ratio of the thickness d1 of the piezoelectric layer 411 to the thickness d2 of the support substrate 412 is, for example, 1:9. The piezoelectric layer 411 is formed over one side of the support substrate 412 . An IDT electrode 42 , a conductive auxiliary member 43 , a peripheral wall 47 and a cover member 48 are provided on the main surface of the piezoelectric layer 411 opposite to the support substrate 412 side.
　支持基板４１２では、圧電体層４１１を伝搬する弾性波の音速よりも、支持基板４１２を伝搬するバルク波の音速が高速である。ここにおいて、支持基板４１２を伝搬するバルク波は、支持基板４１２を伝搬する複数のバルク波のうち最も低音速なバルク波である。 In the support substrate 412 , the acoustic velocity of the bulk wave propagating through the support substrate 412 is higher than the acoustic velocity of the elastic wave propagating through the piezoelectric layer 411 . Here, the bulk wave propagating through the support substrate 412 is the bulk wave having the lowest velocity among the plurality of bulk waves propagating through the support substrate 412 .
　支持基板４１２の厚さｄ２は、１０λ（λ：電極指ピッチにより定まる弾性波の波長）μｍ以上１８０μｍ以下が好適であり、一例として、例えば、１２０μｍである。支持基板４１２がシリコン基板の場合、支持基板４１２の第１主面４１２ａの面方位は、例えば、（１００）面であるが、これに限らず、例えば、支持基板４１２の第１主面４１２ａの面方位は、（１１０）面、（１１１）面等であってもよい。弾性波の伝搬方位は、支持基板４１２の第１主面４１２ａの面方位に制約されずに設定することができる。 The thickness d2 of the support substrate 412 is preferably 10λ (λ: wavelength of elastic wave determined by electrode finger pitch) µm or more and 180 µm or less, for example, 120 µm. When the support substrate 412 is a silicon substrate, the plane orientation of the first main surface 412a of the support substrate 412 is, for example, the (100) plane. The plane orientation may be the (110) plane, the (111) plane, or the like. The propagation direction of elastic waves can be set without being restricted by the plane direction of the first main surface 412 a of the support substrate 412 .
　支持基板４１２は、シリコン基板に限定されない。支持基板４１２は、シリコン、窒化アルミニウム、酸化アルミニウム、炭化ケイ素、窒化ケイ素、サファイア、タンタル酸リチウム、ニオブ酸リチウム、水晶、アルミナ、ジルコニア、コージライト、ムライト、ステアタイト、フォルステライト、マグネシア及びダイヤモンドからなる群から選択される少なくとも１種の材料を含んでいればよい。 The support substrate 412 is not limited to a silicon substrate. Support substrate 412 is made from silicon, aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, sapphire, lithium tantalate, lithium niobate, quartz, alumina, zirconia, cordierite, mullite, steatite, forsterite, magnesia, and diamond. It is sufficient that at least one material selected from the group consisting of is included.
　圧電体層４１１は、互いに対向する第１主面４１１ａ及び第２主面４１１ｂを有する。第１主面４１１ａと第２主面４１１ｂとは、圧電性基板４１の厚さ方向Ｄ１において対向する。 The piezoelectric layer 411 has a first main surface 411a and a second main surface 411b facing each other. The first main surface 411a and the second main surface 411b face each other in the thickness direction D1 of the piezoelectric substrate 41 .
　圧電体層４１１は、例えば、Γ°ＹカットＸ伝搬ＬｉＴａＯ３圧電単結晶から形成されている。Γ°ＹカットＸ伝搬ＬｉＴａＯ３圧電単結晶は、ＬｉＴａＯ３圧電単結晶の３つの結晶軸をＸ軸、Ｙ軸、Ｚ軸とした場合に、Ｘ軸を中心軸としてＹ軸からＺ軸方向にΓ°回転した軸を法線とする面で切断したＬｉＴａＯ３単結晶であって、Ｘ軸方向に弾性表面波が伝搬する単結晶である。圧電体層４１１のカット角は、カット角をΓ［°］、圧電体層４１１のオイラー角を（φ，θ，ψ）をすると、Γ＝θ＋９０°である。ただし、Γと、Γ±１８０×ｎは同義である（結晶学的に等価である）。ここにおいて、ｎは、自然数である。圧電体層４１１は、Γ°ＹカットＸ伝搬ＬｉＴａＯ３圧電単結晶に限定されず、例えば、Γ°ＹカットＸ伝搬ＬｉＴａＯ３圧電セラミックスであってもよい。 The piezoelectric layer 411 is made of, for example, a Γ° Y-cut X-propagating LiTaO 3 piezoelectric single crystal. The Γ° Y-cut X-propagating LiTaO3 piezoelectric single crystal has three crystal axes of the LiTaO3 piezoelectric single crystal as the X axis, the Y axis, and the Z axis. It is a LiTaO 3 single crystal cut along a plane normal to the axis rotated by Γ°, and a single crystal in which a surface acoustic wave propagates in the X-axis direction. The cut angle of the piezoelectric layer 411 is Γ=θ+90° where the cut angle is Γ[°] and the Euler angles of the piezoelectric layer 411 are (φ, θ, ψ). However, Γ and Γ±180×n are synonymous (crystallographically equivalent). Here, n is a natural number. The piezoelectric layer 411 is not limited to the Γ° Y-cut X-propagating LiTaO 3 piezoelectric single crystal, and may be, for example, Γ° Y-cut X-propagating LiTaO 3 piezoelectric ceramics.
　圧電体層４１１の厚さｄ１は、例えば、ＩＤＴ電極４２の電極指ピッチで定まる弾性波の波長をλとしたときに、３．５λ以下である。圧電体層４１１の厚さｄ１が３．５λ以下である場合、弾性波フィルタ２のＱ（Quality factor）値が高くなる。また、圧電体層４１１の厚さｄ１を２．５λ以下とすることで、ＴＣＦ（Temperature Coefficient of Frequency）を小さくすることができる。さらに、圧電体層４１１の厚さｄ１を１．５λ以下とすることで、弾性波の音速の調整が容易になる。なお、圧電体層４１１の厚さｄ１は、３．５λ以下であることに限定されず、３．５λより大きくてもよい。 The thickness d1 of the piezoelectric layer 411 is, for example, 3.5λ or less, where λ is the wavelength of the elastic wave determined by the electrode finger pitch of the IDT electrode 42 . When the thickness d1 of the piezoelectric layer 411 is 3.5λ or less, the Q (Quality factor) value of the acoustic wave filter 2 increases. Also, by setting the thickness d1 of the piezoelectric layer 411 to 2.5λ or less, the TCF (Temperature Coefficient of Frequency) can be reduced. Furthermore, by setting the thickness d1 of the piezoelectric layer 411 to 1.5λ or less, it becomes easy to adjust the sound velocity of the elastic wave. Note that the thickness d1 of the piezoelectric layer 411 is not limited to 3.5λ or less, and may be greater than 3.5λ.
　弾性波フィルタ２では、圧電体層４１１を伝搬する弾性波のモードとして、縦波、ＳＨ波、若しくはＳＶ波、又はこれらが複合したモードが存在する。弾性波フィルタ２では、ＳＨ波を主成分とするモードをメインモードとして使用している。高次モードとは、圧電体層４１１を伝搬する弾性波のメインモードよりも高周波数側に発生するスプリアスモードのことである。圧電体層４１１を伝搬する弾性波のモードが「ＳＨ波を主成分とするモードをメインモード」であるか否かについては、例えば、圧電体層４１１のパラメータ（材料、オイラー角及び厚さ等）、ＩＤＴ電極４２のパラメータ（材料、厚さ及び電極指ピッチ等）等のパラメータを用いて、有限要素法により変位分布を解析し、ひずみを解析することにより、確認することができる。圧電体層４１１のオイラー角は、分析により求めることができる。 In the elastic wave filter 2, as modes of elastic waves propagating through the piezoelectric layer 411, there are longitudinal waves, SH waves, SV waves, or a mode combining these. In the elastic wave filter 2, a mode having SH waves as a main component is used as a main mode. A higher-order mode is a spurious mode generated on the higher frequency side than the main mode of the elastic wave propagating through the piezoelectric layer 411 . Regarding whether or not the mode of the elastic wave propagating through the piezoelectric layer 411 is "the main mode is a mode having an SH wave as a main component", for example, parameters of the piezoelectric layer 411 (material, Euler angle, thickness, etc.) ), and parameters of the IDT electrode 42 (material, thickness, electrode finger pitch, etc.), the displacement distribution is analyzed by the finite element method, and the distortion can be analyzed. The Euler angles of the piezoelectric layer 411 can be obtained by analysis.
　圧電体層４１１の材料は、タンタル酸リチウム（ＬｉＴａＯ３）に限定されず、例えば、ニオブ酸リチウム（ＬｉＮｂＯ３）、酸化亜鉛（ＺｎＯ）、窒化アルミニウム（ＡｌＮ）、又はチタン酸ジルコン酸鉛鉛（ＰＺＴ）であってもよい。圧電体層４１１が、例えば、ＹカットＸ伝搬ＬｉＮｂＯ３圧電単結晶又は圧電セラミックスからなる場合、弾性波フィルタ２は、より結合係数の高いＳＨモードを利用することができる。 The material of the piezoelectric layer 411 is not limited to lithium tantalate ( LiTaO 3 ). PZT). When the piezoelectric layer 411 is made of, for example, a Y-cut X-propagating LiNbO 3 piezoelectric single crystal or piezoelectric ceramics, the acoustic wave filter 2 can utilize the SH mode with a higher coupling coefficient.
　本変形例では、上記の実施形態と同様に、圧電性基板４１には貫通孔７０が設けられている。貫通孔７０の変化点Ｐ３は、支持基板４１２内に存在する。すなわち、本変形例では、レーザ加工によって、圧電性基板４１の第２主面４１ｂから支持基板４１２の厚さ方向の途中までの深さを有する穴部６０が形成される。そして、ドライエッチングによって、支持基板４１２の厚さ方向の残りの部分と圧電体層４１１とが貫通されて貫通孔６１が形成される。 In this modified example, a through hole 70 is provided in the piezoelectric substrate 41 as in the above embodiment. A change point P3 of the through hole 70 exists within the support substrate 412 . That is, in this modification, the hole 60 having a depth from the second main surface 41b of the piezoelectric substrate 41 to the middle of the support substrate 412 in the thickness direction is formed by laser processing. Then, by dry etching, the through-hole 61 is formed by penetrating the remaining portion of the support substrate 412 in the thickness direction and the piezoelectric layer 411 .
　本変形例でも、上記の実施形態と同様に、ビア４４と導電補助部材４３との接触面積を比較的大きくすることができる。 Also in this modified example, the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large, as in the above-described embodiment.
　（５－２）変形例２
　図８に示すように、変形例１において、圧電体層４１１と支持基板４１２との間に、低音速膜４１３と、高音速膜４１４とが設けられていてもよい。低音速膜４１３は、例えば酸化シリコンで形成されている。高音速膜４１４は、例えば窒化シリコンで形成されている。この場合、支持基板４１２上に高音速膜４１４が積層され、高音速膜４１４上に低音速膜４１３が積層され、低音速膜４１３上に圧電体層４１１が積層される。この場合は、圧電性基板４１は、圧電体層４１１、支持基板４１２、低音速膜４１３及び高音速膜４１４を備えている。この場合も、貫通孔７０の変化点Ｐ３は、支持基板４１２内に存在する。本変形例でも、上記の実施形態と同様に、ビア４４と導電補助部材４３との接触面積を比較的大きくすることができる。 (5-2) Modification 2
As shown in FIG. 8, in Modification 1, a low acoustic velocity film 413 and a high acoustic velocity film 414 may be provided between the piezoelectric layer 411 and the support substrate 412 . The low sound velocity film 413 is made of silicon oxide, for example. The high acoustic velocity film 414 is made of silicon nitride, for example. In this case, a high acoustic velocity film 414 is laminated on a support substrate 412 , a low acoustic velocity film 413 is laminated on the high acoustic velocity film 414 , and a piezoelectric layer 411 is laminated on the low acoustic velocity film 413 . In this case, the piezoelectric substrate 41 comprises a piezoelectric layer 411 , a support substrate 412 , a low acoustic velocity film 413 and a high acoustic velocity film 414 . Also in this case, the change point P3 of the through-hole 70 exists within the support substrate 412 . Also in this modified example, the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large, as in the above-described embodiment.
　低音速膜４１３は、圧電体層４１１を伝搬するバルク波の音速よりも、低音速膜４１３を伝搬するバルク波の音速が低速となる膜である。 The low sound velocity film 413 is a film in which the sound velocity of the bulk wave propagating through the low sound velocity film 413 is lower than the sound velocity of the bulk wave propagating through the piezoelectric layer 411 .
　低音速膜４１３は、支持基板４１２と圧電体層４１１との間に設けられている。低音速膜４１３が支持基板４１２と圧電体層４１１との間に設けられていることにより、弾性波の音速が低下する。弾性波は、本質的に低音速な媒質にエネルギーが集中するという性質を有する。したがって、圧電体層４１１内及び弾性波が励振されているＩＤＴ電極内への弾性波のエネルギーの閉じ込め効果を高めることができる。その結果、低音速膜４１３が設けられていない場合に比べて、弾性波フィルタ２の損失を低減し、弾性波フィルタ２のＱ値を高めることができる。 The low sound velocity film 413 is provided between the support substrate 412 and the piezoelectric layer 411 . The sound velocity film 413 provided between the support substrate 412 and the piezoelectric layer 411 reduces the sound velocity of the elastic wave. Elastic waves have the property that their energy is concentrated in a medium that is inherently low in sound velocity. Therefore, the effect of confining the energy of the elastic wave in the piezoelectric layer 411 and the IDT electrode where the elastic wave is excited can be enhanced. As a result, the loss of the elastic wave filter 2 can be reduced and the Q value of the elastic wave filter 2 can be increased as compared with the case where the low sound velocity film 413 is not provided.
　低音速膜４１３の材料は、例えば、酸化ケイ素である。なお、低音速膜４１３の材料は、酸化ケイ素に限定されず、例えば、ガラス、酸窒化ケイ素、酸化タンタル、酸化ケイ素にフッ素、炭素、若しくはホウ素を加えた化合物、又は、上記各材料を主成分とする材料であってもよい。 The material of the low-temperature film 413 is, for example, silicon oxide. The material of the low-low-speed film 413 is not limited to silicon oxide. It may be a material that
　低音速膜４１３が酸化ケイ素の場合、温度特性を改善することができる。タンタル酸リチウムの弾性定数は負の温度特性を有し、酸化ケイ素は正の温度特性を有する。したがって、弾性波フィルタ２では、ＴＣＦの絶対値を小さくすることができる。 When the low-temperature film 413 is silicon oxide, the temperature characteristics can be improved. The elastic constant of lithium tantalate has a negative temperature characteristic, and silicon oxide has a positive temperature characteristic. Therefore, the elastic wave filter 2 can reduce the absolute value of TCF.
　低音速膜４１３の厚さは、電極指ピッチで定まる弾性波の波長をλとすると、２．０λ以下であることが好ましい。低音速膜４１３の厚さは、例えば６７０ｎｍである。低音速膜４１３の厚さを２．０λ以下とすることにより、膜応力を低減させることができ、その結果、弾性波フィルタ２の製造時に支持基板４１２の元になるシリコンウェハの反りを低減させることができ、良品率の向上及び特性の安定化が可能となる。 The thickness of the low sound velocity film 413 is preferably 2.0λ or less, where λ is the wavelength of the elastic wave determined by the electrode finger pitch. The thickness of the low sound velocity film 413 is, for example, 670 nm. By setting the thickness of the low sound velocity film 413 to 2.0λ or less, the film stress can be reduced, and as a result, warping of the silicon wafer from which the support substrate 412 is based when the acoustic wave filter 2 is manufactured is reduced. This makes it possible to improve yield and stabilize characteristics.
　また、弾性波フィルタ２では、圧電性基板４１が、例えば低音速膜４１３と圧電体層４１１との間に介在する密着層を含んでいてもよい。これにより、低音速膜４１３と圧電体層４１１との密着性を向上させることができる。密着層は、例えば、樹脂（エポキシ樹脂、ポリイミド樹脂等）、金属等からなる。また、弾性波フィルタ２では、圧電性基板４１が、密着層に限らず、誘電体膜を、低音速膜４１３と圧電体層４１１との間、圧電体層４１１上、又は低音速膜４１３下のいずれかに備えてもよい。 Further, in the elastic wave filter 2, the piezoelectric substrate 41 may include an adhesion layer interposed between the low-temperature velocity film 413 and the piezoelectric layer 411, for example. As a result, the adhesion between the low sound velocity film 413 and the piezoelectric layer 411 can be improved. The adhesion layer is made of, for example, resin (epoxy resin, polyimide resin, etc.), metal, or the like. Further, in the elastic wave filter 2, the piezoelectric substrate 41 is not limited to the adhesion layer, and the dielectric film is formed between the low-temperature velocity film 413 and the piezoelectric layer 411, above the piezoelectric layer 411, or under the low-temperature velocity film 413. You may prepare for either.
　高音速膜４１４は、支持基板４１２と低音速膜４１３との間に設けられている。ここにおいて、高音速膜４１４は、支持基板４１２上に設けられている。「支持基板４１２上に設けられている」とは、支持基板４１２上に直接的に設けられている場合と、支持基板４１２上に間接的に設けられている場合と、を含む。 The high acoustic velocity film 414 is provided between the support substrate 412 and the low acoustic velocity film 413 . Here, the high acoustic velocity film 414 is provided on the support substrate 412 . “Provided over the support substrate 412 ” includes the case of being directly provided over the support substrate 412 and the case of being indirectly provided over the support substrate 412 .
　高音速膜４１４は、圧電体層４１１を伝搬する弾性波の音速よりも、高音速膜４１４を伝搬するバルク波の音速が高速となる膜である。高音速膜４１４の厚さは、例えば２００ｎｍ、３００ｎｍ、４００ｎｍである。 The high acoustic velocity film 414 is a film in which the sound velocity of bulk waves propagating through the high acoustic velocity film 414 is faster than the sound velocity of elastic waves propagating through the piezoelectric layer 411 . The thickness of the high acoustic velocity film 414 is, for example, 200 nm, 300 nm, and 400 nm.
　高音速膜４１４は、メインモードの弾性波のエネルギーが高音速膜４１４より下の構造に漏れることを抑制するように機能する。この弾性波フィルタ２では、高音速膜４１４の厚さが十分に厚い場合、メインモードの弾性波のエネルギーは圧電体層４１１及び低音速膜４１３の全体に分布し、高音速膜４１４の低音速膜４１３側の一部にも分布し、支持基板４１２には分布しないことになる。高音速膜４１４により弾性波を閉じ込めるメカニズムは非漏洩なＳＨ波であるラブ波型の表面波の場合と同様のメカニズムであり、例えば、文献「弾性表面波デバイスシミュレーション技術入門」、橋本研也、リアライズ社、ｐ．２６－２８に記載されている。上記メカニズムは、音響多層膜によるブラッグ反射器を用いて弾性波を閉じ込めるメカニズムとは異なる。 The high acoustic velocity film 414 functions to suppress the energy of the main mode elastic wave from leaking to the structure below the high acoustic velocity film 414 . In this acoustic wave filter 2, when the high acoustic velocity film 414 is sufficiently thick, the energy of the main mode elastic wave is distributed throughout the piezoelectric layer 411 and the low acoustic velocity film 413, and the low acoustic velocity of the high acoustic velocity film 414 It is distributed in a part of the film 413 side and is not distributed in the support substrate 412 . The mechanism for confining the elastic wave by the high-speed film 414 is the same mechanism as in the case of Love wave type surface waves, which are non-leaky SH waves. Realize, p. 26-28. The above mechanism is different from the mechanism of confining elastic waves using a Bragg reflector made of an acoustic multilayer film.
　高音速膜４１４の材料は、例えば、ダイヤモンドライクカーボン、窒化アルミニウム、酸化アルミニウム、炭化ケイ素、窒化ケイ素、シリコン、サファイア、圧電体（タンタル酸リチウム、ニオブ酸リチウム、又は水晶）、アルミナ、ジルコニア、コージライト、ムライト、ステアタイト、フォルステライト、マグネシア、及びダイヤモンドからなる群から選択される少なくとも１種の材料である。高音速膜４１４の材料は、上述したいずれかの材料を主成分とする材料、又は、上述したいずれかの材料を含む混合物を主成分とする材料であってもよい。 The material of the high-sonic film 414 is, for example, diamond-like carbon, aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon, sapphire, piezoelectric material (lithium tantalate, lithium niobate, or crystal), alumina, zirconia, cordage. At least one material selected from the group consisting of light, mullite, steatite, forsterite, magnesia, and diamond. The material of the high acoustic velocity film 414 may be a material containing any of the materials described above as a main component, or a material containing a mixture containing any of the materials described above as a main component.
　高音速膜４１４の厚さに関しては、弾性波を圧電体層４１１及び低音速膜４１３に閉じ込める機能を高音速膜４１４が有するため、高音速膜４１４の厚さは厚いほど望ましい。圧電性基板４１は、高音速膜４１４、低音速膜４１３及び圧電体層４１１以外の他の膜として密着層、誘電体膜等を有してもよい。 Regarding the thickness of the high acoustic velocity film 414, the thicker the high acoustic velocity film 414, the better, because the high acoustic velocity film 414 has the function of confining the elastic wave in the piezoelectric layer 411 and the low acoustic velocity film 413. The piezoelectric substrate 41 may have an adhesion layer, a dielectric film, etc. as films other than the high acoustic velocity film 414 , the low acoustic velocity film 413 and the piezoelectric layer 411 .
　（５－３）変形例３
　変形例２において高音速膜４１４は省略されてもよい。すなわち、圧電体層４１１と支持基板４１２との間に、低音速膜４１３が設けられていてもよい。低音速膜４１３は、例えば酸化シリコンで形成されている。支持基板４１２は、高音速支持基板である。この場合、高音速支持基板である支持基板４１２上に低音速膜４１３が積層され、低音速膜４１３上に圧電体層４１１が積層される。この場合は、圧電性基板４１は、圧電体層４１１、支持基板４１２及び低音速膜４１３を備えている。この場合も、貫通孔７０の変化点Ｐ３は、支持基板４１２内に存在する。本変形例でも、上記の実施形態と同様に、ビア４４と導電補助部材４３との接触面積を比較的大きくすることができる。 (5-3) Modification 3
In Modification 2, the high acoustic velocity film 414 may be omitted. That is, the low-temperature velocity film 413 may be provided between the piezoelectric layer 411 and the support substrate 412 . The low sound velocity film 413 is made of silicon oxide, for example. The support substrate 412 is a high acoustic velocity support substrate. In this case, the low sound velocity film 413 is laminated on the support substrate 412 which is the high sound velocity support substrate, and the piezoelectric layer 411 is laminated on the low sound velocity film 413 . In this case, the piezoelectric substrate 41 comprises a piezoelectric layer 411 , a support substrate 412 and a low acoustic velocity film 413 . Also in this case, the change point P3 of the through-hole 70 exists within the support substrate 412 . Also in this modified example, the contact area between the via 44 and the conductive auxiliary member 43 can be made relatively large, as in the above-described embodiment.
　（６）態様
　以上説明した実施形態から明らかなように、以下の態様を取り得る。 (6) Aspects As is clear from the embodiments described above, the following aspects are possible.
　第１の態様の弾性波フィルタ（２）は、圧電性基板（４１）と、機能電極（４２）と、導電部材（４３）と、外部端子（４５）と、ビア（４４）と、を備える。圧電性基板（４１）は、互いに対向する第１主面（４１ａ）及び第２主面（４１ｂ）を有する。圧電性基板（４１）は、厚さ方向（Ｄ１）の少なくとも一部に圧電性を有する。機能電極（４２）は、圧電性基板（４１）の第１主面（４１ａ）に配置されている。導電部材（４３）は、圧電性基板（４１）の第１主面（４１ａ）に配置され、機能電極（４２）に接続されている。外部端子（４５）は、圧電性基板（４１）の第２主面（４１ｂ）に配置されている。ビア（４４）は、圧電性基板（４１）を厚さ方向（Ｄ１）に貫通し、外部端子（４５）と導電部材（４３）とを接続する。第２主面（４１ｂ）に直交する断面での断面視において、ビア（４４）と圧電性基板（４１）の第１主面（４１ａ）及び第２主面（４１ｂ）との交点をそれぞれ第１交点（Ｐ１）及び第２交点（Ｐ２）とし、ビア（４４）の外周面（４４ｃ）において外周面（４４ｃ）の傾斜が変化する点を変化点（Ｐ３）とし、第１交点（Ｐ１）、第２交点（Ｐ２）及び変化点（Ｐ３）は、圧電性基板（４）の第２主面（４１ｂ）に平行な方向においてビア（４４）における互いに同じ側にある。変化点（Ｐ３）と第２交点（Ｐ２）とを結ぶ第１線分（Ｈ１）と第２主面（４１ｂ）とが成す鋭角を第１角（α）とし、変化点（Ｐ３）と第１交点（Ｐ１）とを結ぶ第２線分と仮想線（Ｌ１）とが成す鋭角を第２角（β）とする。仮想線（Ｌ１）は、変化点（Ｐ３）を通って圧電性基板（４１）の第２主面（４１ｂ）に平行である。第２角（β）は、第１角（α）よりも大きい。 An elastic wave filter (2) of a first aspect comprises a piezoelectric substrate (41), a functional electrode (42), a conductive member (43), an external terminal (45), and vias (44). . The piezoelectric substrate (41) has a first major surface (41a) and a second major surface (41b) facing each other. The piezoelectric substrate (41) has piezoelectricity at least partially in the thickness direction (D1). The functional electrode (42) is arranged on the first main surface (41a) of the piezoelectric substrate (41). A conductive member (43) is disposed on the first main surface (41a) of the piezoelectric substrate (41) and connected to the functional electrode (42). The external terminals (45) are arranged on the second main surface (41b) of the piezoelectric substrate (41). The via (44) penetrates the piezoelectric substrate (41) in the thickness direction (D1) and connects the external terminal (45) and the conductive member (43). In a cross-sectional view in a cross section perpendicular to the second main surface (41b), intersections between the via (44) and the first main surface (41a) and the second main surface (41b) of the piezoelectric substrate (41) A first intersection point (P1) and a second intersection point (P2) are defined, and a change point (P3) is a point at which the inclination of the outer circumferential surface (44c) of the via (44) changes, and a first intersection point (P1). , the second intersection point (P2) and the change point (P3) are on the same side of the via (44) in a direction parallel to the second main surface (41b) of the piezoelectric substrate (4). A first angle (α) is an acute angle formed by a first line segment (H1) connecting the point of change (P3) and the second intersection (P2) and the second main surface (41b). A second angle (β) is an acute angle formed by a second line segment connecting the first intersection point (P1) and the imaginary line (L1). The imaginary line (L1) passes through the point of change (P3) and is parallel to the second main surface (41b) of the piezoelectric substrate (41). The second angle (β) is greater than the first angle (α).
　この構成によれば、第２角（β）が第１角（α）よりも大きいため、第２角（β）と第１角（α）とが同じ大きさである場合と比べて、上記の断面視において、圧電性基板（４１）の第１主面（４１ａ）でのビア（４４）の幅（Ｗ１）を大きくできる。これにより、ビア（４４）と導電部材（４３）との接触面積を比較的大きくできる。この結果、ビア（４４）と導電部材との接続信頼性を向上できかつフィルタ特性の劣化を抑制できる。 According to this configuration, the second angle (β) is larger than the first angle (α). , the width (W1) of the via (44) on the first main surface (41a) of the piezoelectric substrate (41) can be increased. Thereby, the contact area between the via (44) and the conductive member (43) can be made relatively large. As a result, it is possible to improve the connection reliability between the via (44) and the conductive member, and suppress deterioration of filter characteristics.
　第２の態様の弾性波フィルタ（２）では、第１の態様において、圧電性基板（４１）は、圧電体層（４１１）と、支持基板（４１２）とを有する。支持基板（４１２）は、圧電体層（４１１）における外部端子（４５）の側に配置されている。 In the acoustic wave filter (2) of the second aspect, in the first aspect, the piezoelectric substrate (41) has a piezoelectric layer (411) and a support substrate (412). The support substrate (412) is arranged on the piezoelectric layer (411) on the side of the external terminal (45).
　この構成によれば、圧電性基板（４１）が支持基板（４１２）を含む構成において、ビア（４４）と導電部材（４３）との接触面積を比較的大きくできる。 According to this configuration, in the configuration in which the piezoelectric substrate (41) includes the support substrate (412), the contact area between the via (44) and the conductive member (43) can be made relatively large.
　第３の態様の弾性波フィルタ（２）では、第２の態様において、変化点（Ｐ３）は、支持基板（４１２）内に存在する。 In the acoustic wave filter (2) of the third aspect, in the second aspect, the change point (P3) exists within the support substrate (412).
　この構成によれば、変化点（Ｐ３）が圧電体層（４１１）内に存在する構成において、ビア（４４）と導電部材（４３）との接触面積を大きくできる。 According to this configuration, the contact area between the via (44) and the conductive member (43) can be increased in the configuration where the change point (P3) exists within the piezoelectric layer (411).
　第４の態様の弾性波フィルタ（２）では、第２又は第３の態様において、圧電体層（４１１）は、タンタル酸リチウム又はニオブ酸リチウムである。 In the acoustic wave filter (2) of the fourth aspect, in the second or third aspect, the piezoelectric layer (411) is lithium tantalate or lithium niobate.
　この構成によれば、圧電体層（４１１）がタンタル酸リチウム又はニオブ酸リチウムである構成において、ビア（４４）と導電部材（４３）との接触面積を比較的大きくできる。 According to this configuration, in a configuration in which the piezoelectric layer (411) is lithium tantalate or lithium niobate, the contact area between the via (44) and the conductive member (43) can be made relatively large.
　第５の態様の弾性波フィルタ（２）では、第２又は第３の態様において、支持基板（４１２）は、シリコン又はサファイアである。 In the acoustic wave filter (2) of the fifth aspect, in the second or third aspect, the supporting substrate (412) is silicon or sapphire.
　この構成によれば、支持基板（４１２）がシリコン又はサファイアである構成において、ビア（４４）と導電部材（４３）との接触面積を比較的大きくできる。 According to this configuration, the contact area between the via (44) and the conductive member (43) can be made relatively large in the configuration where the supporting substrate (412) is silicon or sapphire.
　第６の態様の弾性波フィルタ（２）は、第１～第５の態様のいずれか１つにおいて、周壁（４７）と、カバー部材（４８）と、を備える。周壁（４７）は、圧電性基板（４１）の第１主面（４１ａ）に配置され、機能電極（４２）及び導電部材（４３）を囲む。カバー部材（４８）は、周壁（４７）における第１主面（４１ａ）の側とは反対側の開口を覆う。 The elastic wave filter (2) of the sixth aspect comprises a peripheral wall (47) and a cover member (48) in any one of the first to fifth aspects. A peripheral wall (47) is disposed on the first major surface (41a) of the piezoelectric substrate (41) and surrounds the functional electrode (42) and the conductive member (43). The cover member (48) covers the opening of the peripheral wall (47) on the side opposite to the first main surface (41a).
　この構成によれば、周壁（４７）とカバー部材（４８）を備える構成において、ビア（４４）と導電部材（４３）との接触面積を比較的大きくできる。 According to this configuration, the contact area between the via (44) and the conductive member (43) can be made relatively large in the configuration including the peripheral wall (47) and the cover member (48).
　第７の態様の弾性波フィルタ（２）の製造方法は、第１工程と、第２工程と、第３工程と、第４工程とを備える。第１工程では、基板（４１０）を用意する。基板（４１０）は、互いに対向する第１主面（４１０ａ）及び第２主面（４１０ｂ）を有し、厚さ方向の少なくとも一部に圧電性を有する。基板（４１０）には、第１主面（４１０ａ）において、機能電極（４２）及び機能電極（４２）に接続された導電部材（４３）が配置されている。第２工程では、基板（４１０）において、厚さ方向に貫通する貫通孔（７０）を有する圧電性基板（４１）を形成する。第３工程では、圧電性基板（４１）の貫通孔（７０）の内部において、導電部材（４３）に接続するようにビア（４４）を形成する。第４工程では、圧電性基板（４１）の主面（４１ｂ）に、ビア（４４）に接続する外部端子（４５）を少なくとも１つ含む複数の外部端子（４５）を形成する。第２工程では、レーザ加工によって、基板（４１０）の第２主面（４１０ｂ）から基板（４１０）の第１主面（４１０ａ）と第２主面（４１０ｂ）との間の位置までの穴部（６０）を形成する。そして、ドライエッチングによって、穴部（６０）の底面（６０ａ）と基板（４１０）の第１主面（４１０ａ）との間を貫通させることで、貫通孔（７０）を形成する。 The method for manufacturing the elastic wave filter (2) of the seventh aspect includes a first step, a second step, a third step, and a fourth step. In a first step, a substrate (410) is provided. The substrate (410) has a first main surface (410a) and a second main surface (410b) facing each other, and has piezoelectricity in at least a part of the thickness direction. A functional electrode (42) and a conductive member (43) connected to the functional electrode (42) are arranged on the substrate (410) on the first main surface (410a). In the second step, a piezoelectric substrate (41) having a through hole (70) penetrating in the thickness direction is formed in the substrate (410). In the third step, a via (44) is formed inside the through hole (70) of the piezoelectric substrate (41) so as to connect to the conductive member (43). In a fourth step, a plurality of external terminals (45) including at least one external terminal (45) connected to vias (44) are formed on the main surface (41b) of the piezoelectric substrate (41). In a second step, a hole is formed by laser processing from the second main surface (410b) of the substrate (410) to a position between the first main surface (410a) and the second main surface (410b) of the substrate (410). forming part (60); Then, by dry etching, a through hole (70) is formed by penetrating between the bottom surface (60a) of the hole (60) and the first main surface (410a) of the substrate (410).
　この構成によれば、第２角（β）が第１角（α）よりも大きいビア（４４）を形成できる。これにより、第２角（β）と第１角（α）とが同じ大きさである場合と比べて、上記の断面視において、圧電性基板（４１）の第１主面（４１ａ）でのビア（４４）の幅（Ｗ１）を大きくできる。これにより、ビア（４４）と導電部材（４３）との接触面積を比較的大きくできる。この結果、ビア（４４）と導電部材との接続信頼性を向上できかつフィルタ特性の劣化を抑制できる。 According to this configuration, a via (44) having a second angle (β) larger than the first angle (α) can be formed. As a result, compared to the case where the second angle (β) and the first angle (α) have the same size, in the above cross-sectional view, the first main surface (41a) of the piezoelectric substrate (41) The width (W1) of the via (44) can be increased. Thereby, the contact area between the via (44) and the conductive member (43) can be made relatively large. As a result, it is possible to improve the connection reliability between the via (44) and the conductive member, and suppress deterioration of filter characteristics.
　第８の態様の高周波モジュール（１）は、第１～第６の態様のいずれか１つの弾性波フィルタ（２）と、実装基板（１１）と、を備える。実装基板（１１）は、弾性波フィルタ（２）を実装する。 A high-frequency module (1) of an eighth aspect comprises an acoustic wave filter (2) of any one of the first to sixth aspects and a mounting substrate (11). A mounting substrate (11) mounts an elastic wave filter (2).
　この構成によれば、上述の作用効果を有する弾性波フィルタ（２）を備える高周波モジュール（１）を提供できる。 According to this configuration, it is possible to provide a high-frequency module (1) including an elastic wave filter (2) having the above-described effects.
　第９の態様の通信装置（１００）は、第８の態様の高周波モジュール（１）と、信号処理回路（２０）と、を備える。信号処理回路（２０）は、高周波モジュール（１）に接続されており、高周波信号を信号処理する。 A communication device (100) of the ninth aspect comprises the high-frequency module (1) of the eighth aspect and a signal processing circuit (20). A signal processing circuit (20) is connected to the high frequency module (1) and processes a high frequency signal.
　この構成によれば、上述の作用効果を有する高周波モジュール（１）を備える通信装置（１００）を提供できる。 According to this configuration, it is possible to provide the communication device (100) including the high-frequency module (1) having the above-described effects.
　１　高周波モジュール
　２　弾性波フィルタ
　３　スイッチ
　３ａ　共通端子
　３ｂ　選択端子
　３ｃ　選択端子
　４　受信フィルタ
　５　送信フィルタ
　６，７　整合回路
　８　ローノイズアンプ
　９　パワーアンプ
　１０　外部接続端子
　１０Ａ　アンテナ端子
　１０Ｂ　信号出力端子
　１０Ｃ　信号入力端子
　１１　実装基板
　１１ａ　第１主面
　２０　信号処理回路
　２１　ＲＦ信号処理回路
　２２　ベースバンド信号処理回路
　４０　アンテナ
　４１　圧電性基板
　４１ａ　第１主面
　４１ｂ　第２主面
　４２　ＩＤＴ電極（機能電極）
　４３　導電補助部材（導電部材）
　４４　ビア
　４４ａ　側辺
　４４ｂ　側辺
　４４ｃ　外周面
　４５　外部端子
　４６　接合層
　４７　周壁
　４８　カバー部材
　６０　穴部
　６０ａ　底面
　６０ｂ　内周面
　６１　貫通孔
　６１ｂ　内周面
　７０　貫通孔
　７０ｂ　内周面
　１００　通信装置
　４１１　圧電体層
　４１２　支持基板
　４１４　高音速膜
　４１３　低音速膜
　４２２　櫛型電極
　４２３　電極指
　４２４　バスバー
　４４１　第１柱部
　４４２　第２柱部
　Ｄ１　厚さ方向
　ｄ１，ｄ２　厚さ
　Ｈ１　第１線分
　Ｈ２　第２線分
　Ｋ２　間隔
　Ｌ１　仮想線
　Ｐ１　第１交点
　Ｐ２　第２交点
　Ｐ３　変化点
　Ｑ１，Ｑ２　表面部分
　Ｒ０～Ｒ３　信号経路
　Ｗ１　幅
　Ｗ２　直径（幅）
　Ｗ３　直径
　α　第１角
　β　第２角 1 high-frequency module 2 elastic wave filter 3 switch 3a common terminal 3b selection terminal 3c selection terminal 4 reception filter 5 transmission filter 6, 7 matching circuit 8 low noise amplifier 9 power amplifier 10 external connection terminal 10A antenna terminal 10B signal output terminal 10C signal input terminal REFERENCE SIGNS LIST 11 mounting substrate 11a first main surface 20 signal processing circuit 21 RF signal processing circuit 22 baseband signal processing circuit 40 antenna 41 piezoelectric substrate 41a first main surface 41b second main surface 42 IDT electrode (functional electrode)
43 conductive auxiliary member (conductive member)
44 via 44a side 44b side 44c outer peripheral surface 45 external terminal 46 bonding layer 47 peripheral wall 48 cover member 60 hole 60a bottom surface 60b inner peripheral surface 61 through hole 61b inner peripheral surface 70 through hole 70b inner peripheral surface 100 communication device 411 piezoelectric Body layer 412 Support substrate 414 High acoustic velocity film 413 Low acoustic velocity film 422 Comb-shaped electrode 423 Electrode finger 424 Bus bar 441 First column 442 Second column D1 Thickness direction d1, d2 Thickness H1 First line segment H2 Second line minute K2 interval L1 imaginary line P1 first intersection point P2 second intersection point P3 change point Q1, Q2 surface portion R0 to R3 signal path W1 width W2 diameter (width)
W3 Diameter α 1st angle β 2nd angle

Claims (9)

  1. 　互いに対向する第１主面及び第２主面を有し、厚さ方向の少なくとも一部に圧電性を有する圧電性基板と、
    　前記圧電性基板の前記第１主面に配置された機能電極と、
    　前記圧電性基板の前記第１主面に配置され、前記機能電極に接続された導電部材と、
    　前記圧電性基板の前記第２主面に配置された外部端子と、
    　前記圧電性基板を厚さ方向に貫通し、前記外部端子と前記導電部材とを接続するビアと、を備え、
    　前記第２主面に直交する断面での断面視において、
    　　前記ビアと前記圧電性基板の前記第１主面及び前記第２主面との交点をそれぞれ第１交点及び第２交点とし、
    　　前記ビアの外周面において前記外周面の傾斜が変化する点を変化点とし、
    　　前記第１交点、前記第２交点及び前記変化点は、前記圧電性基板の前記第２主面に平行な方向において前記ビアにおける互いに同じ側にあり、
    　　前記変化点と前記第２交点とを結ぶ第１線分と前記第２主面とが成す鋭角を第１角とし、前記変化点と前記第１交点とを結ぶ第２線分と、前記変化点を通って前記圧電性基板の前記第２主面に平行な仮想線とが成す鋭角を第２角とし、
    　前記第２角は、前記第１角よりも大きい、
    弾性波フィルタ。     a piezoelectric substrate having a first main surface and a second main surface facing each other and having piezoelectricity in at least a part of the thickness direction;
    a functional electrode disposed on the first main surface of the piezoelectric substrate;
    a conductive member disposed on the first main surface of the piezoelectric substrate and connected to the functional electrode;
    external terminals arranged on the second main surface of the piezoelectric substrate;
    a via that penetrates the piezoelectric substrate in a thickness direction and connects the external terminal and the conductive member;
    In a cross-sectional view in a cross section orthogonal to the second main surface,
    a first intersection point and a second intersection point, respectively, between the via and the first main surface and the second main surface of the piezoelectric substrate;
    A change point is a point at which the inclination of the outer peripheral surface changes on the outer peripheral surface of the via,
    the first intersection point, the second intersection point, and the change point are on the same side of the via in a direction parallel to the second main surface of the piezoelectric substrate;
    An acute angle formed by a first line segment connecting the point of change and the second intersection and the second main surface is defined as a first angle, a second line segment connecting the point of change and the first intersection, and the change an acute angle formed by an imaginary line passing through a point and parallel to the second main surface of the piezoelectric substrate is defined as a second angle;
    the second angle is greater than the first angle;
    Acoustic wave filter.
  2. 　前記圧電性基板は、
    　　圧電体層と、
    　　前記圧電体層における前記外部端子の側に配置された支持基板と、を有する、
    請求項１に記載の弾性波フィルタ。     The piezoelectric substrate is
    a piezoelectric layer;
    a support substrate disposed on the piezoelectric layer on the side of the external terminal;
    The elastic wave filter according to claim 1.
  3. 　前記変化点は、前記支持基板内に存在する、
    請求項２に記載の弾性波フィルタ。     wherein the change point exists within the support substrate;
    The elastic wave filter according to claim 2.
  4. 　前記圧電体層は、タンタル酸リチウム又はニオブ酸リチウムである、
    請求項２又は３に記載の弾性波フィルタ。     The piezoelectric layer is lithium tantalate or lithium niobate,
    The elastic wave filter according to claim 2 or 3.
  5. 　前記支持基板は、シリコン又はサファイアである、
    請求項２又は３に記載の弾性波フィルタ。     The support substrate is silicon or sapphire,
    The elastic wave filter according to claim 2 or 3.
  6. 　前記圧電性基板の前記第１主面に配置され、前記機能電極及び前記導電部材を囲む周壁と、
    　前記周壁における前記第１主面の側とは反対側の開口を覆うカバー部材と、を備える、
    請求項１～５のいずれか１項に記載の弾性波フィルタ。     a peripheral wall disposed on the first main surface of the piezoelectric substrate and surrounding the functional electrode and the conductive member;
    a cover member that covers an opening on the side of the peripheral wall opposite to the side of the first main surface,
    The elastic wave filter according to any one of claims 1 to 5.
  7. 　互いに対向する第１主面及び第２主面を有し、厚さ方向の少なくとも一部に圧電性を有する基板であって、前記第１主面において機能電極及び前記機能電極に接続された導電部材が配置された基板を用意する第１工程と、
    　前記基板において厚さ方向に貫通する貫通孔を有する圧電性基板を形成する第２工程と、
    　前記圧電性基板の前記貫通孔において、前記導電部材に接続するようにビアを形成する第３工程と、
    　前記圧電性基板の主面に、前記ビアに接続する外部端子を少なくとも１つ含む複数の外部端子を形成する第４工程と、を備え、
    　前記第２工程では、
    　　レーザ加工によって、前記基板の前記第２主面から前記基板の前記第１主面と前記第２主面との間の位置までの穴部を形成し、ドライエッチングによって、前記穴部の底面と前記基板の前記第１主面との間を貫通させることで、前記貫通孔を形成する、
    弾性波フィルタの製造方法。     A substrate having a first main surface and a second main surface facing each other and having piezoelectricity in at least a part of a thickness direction, the substrate having a functional electrode and a conductive member connected to the functional electrode on the first main surface. A first step of preparing a substrate on which members are arranged;
    a second step of forming a piezoelectric substrate having a through hole extending through the substrate in a thickness direction;
    a third step of forming a via in the through hole of the piezoelectric substrate so as to connect to the conductive member;
    a fourth step of forming a plurality of external terminals including at least one external terminal connected to the via on the main surface of the piezoelectric substrate;
    In the second step,
    A hole is formed from the second main surface of the substrate to a position between the first main surface and the second main surface of the substrate by laser processing, and the bottom surface of the hole and the bottom surface are formed by dry etching. The through hole is formed by penetrating between the first main surface of the substrate,
    A method for manufacturing an elastic wave filter.
  8. 　請求項１～６のいずれか１項に記載の弾性波フィルタと、
    　前記弾性波フィルタを実装する実装基板と、を備える、
    高周波モジュール。     An elastic wave filter according to any one of claims 1 to 6;
    a mounting substrate on which the acoustic wave filter is mounted,
    high frequency module.
  9. 　請求項８に記載の高周波モジュールと、
    　前記高周波モジュールに接続されており、高周波信号を信号処理する信号処理回路と、を備える、
    通信装置。     The high frequency module according to claim 8;
    a signal processing circuit that is connected to the high-frequency module and processes a high-frequency signal;
    Communication device.
PCT/JP2022/005133 2021-02-17 2022-02-09 Elastic wave filter, method for manufacturing elastic wave filter, high-frequency module, and communication apparatus WO2022176738A1 (en)

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WO2016084936A1 (en) * 2014-11-28 2016-06-02 京セラ株式会社 Saw device and method for manufacturing saw device
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