Elastic wave device and multiplexer

Abstract

The invention provides an elastic wave device and a multiplexer, which suppress deterioration of passing characteristics. A filter (20) is provided with a series arm resonator (s21), parallel arm resonators (p21 to p24), a laminated substrate (40) having main surfaces (40a and 40b), a piezoelectric substrate (50), and a bump electrode (70 (121)) disposed on the main surface (50a), the parallel arm resonator (p21) including an IDT electrode disposed on the main surface (50a), the bump electrode being connected to the IDT electrode, and the piezoelectric substrate (50) being disposed on the main surface (50a). The laminated substrate has a planar electrode (410) disposed on the main surface (40a) and joined to the bump electrode, a planar electrode (440) disposed on the main surface (40b) and connected to the ground, and a plurality of via conductors (81) connecting the planar electrode (410) and the planar electrode (440), the bump electrode being located between the via conductors (81a, 81b) connected to the planar electrode (410) in a plan view of the main surface (40a), and the bump electrode being located between the via conductors (81a, 81b) connected to the planar electrode (410) in a plan view of the main surface (40a) in a plan view of the main surface (40a). The parallel arm resonator (p21) has the highest resonance frequency among the plurality of parallel arm resonators (p21 to p24).

Description

Technical Field

[0001] The present invention relates to an elastic wave device and a multiplexer. Background Art

[0002] Patent Document 1 discloses a wave splitter (elastic wave device) having a plurality of surface acoustic wave filters formed on a piezoelectric substrate and a mounting substrate having a plurality of dielectric layers. The bump electrodes arranged on the piezoelectric substrate are flip-chip bonded to the land electrodes arranged on the mounting substrate, thereby realizing a small elastic wave device.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2015 / 016203 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, the elastic wave device described in Patent Document 1 has a problem in that the transmission characteristics of the elastic wave device deteriorate due to positional deviation between the bump electrodes and the land electrodes during flip-chip bonding.

[0008] Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an elastic wave device and a multiplexer in which degradation of transmission characteristics is suppressed.

[0009] Technical solutions to solve problems

[0010] To achieve the above object, an elastic wave device according to one embodiment of the present invention comprises: a first series arm resonator arranged in a series arm path connecting a first input / output terminal and a second input / output terminal; a plurality of parallel arm resonators connected between the series arm path and a ground; a first substrate having a first main surface and a second main surface facing each other and having a plurality of dielectric layers; a second substrate having a third main surface arranged face-to-face with the first main surface; and a first protruding electrode arranged on the third main surface, the first series arm resonator including a first functional electrode arranged on the third main surface, and a first parallel arm resonator among the plurality of parallel arm resonators including a first functional electrode arranged on the third main surface. The first substrate comprises: a first planar electrode disposed in a first dielectric layer among a plurality of dielectric layers and bonded to the first protruding electrode; a second planar electrode disposed in a second dielectric layer closer to the second main surface than the first dielectric layer among the plurality of dielectric layers and connected to ground; and a plurality of via conductors connecting the first planar electrode and the second planar electrode, wherein, when the first main surface is viewed from above, the first protruding electrode is located between two via conductors among the plurality of via conductors connected to the first planar electrode, and the first parallel arm resonator has the highest resonance frequency among the plurality of parallel arm resonators.

[0011] In one embodiment of the present invention, an elastic wave device includes: a first series arm resonator disposed in a series arm path connecting a first input / output terminal and a second input / output terminal; a plurality of parallel arm resonators connected between the series arm path and a ground; a first substrate having a first main surface and a second main surface facing each other and having a plurality of dielectric layers; a second substrate having a third main surface disposed face-to-face with the first main surface; and a first protruding electrode disposed on the third main surface, the first series arm resonator including a first functional electrode disposed on the third main surface, a first parallel arm resonator among the plurality of parallel arm resonators including a second functional electrode disposed on the third main surface, the first protruding electrode and the second protruding electrode being connected to each other. The functional electrodes are connected, and the first substrate comprises: a first plane electrode, which is arranged in the first dielectric layer among the plurality of dielectric layers and is bonded to the first protruding electrode; a second plane electrode, which is arranged in the second dielectric layer among the plurality of dielectric layers and is closer to the second main surface than the first dielectric layer and is connected to the ground; and a plurality of via conductors, which connect the first plane electrode and the second plane electrode. When the first main surface is viewed from above, the first protruding electrode is located between two via conductors among the plurality of via conductors connected to the first plane electrode. The first functional electrode and the second functional electrode are IDT electrodes respectively, and the first parallel arm resonator has the smallest electrode finger pitch of the IDT electrode among the plurality of parallel arm resonators.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide an elastic wave device and a multiplexer in which degradation of transmission characteristics is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a circuit structure diagram of a multiplexer involved in an embodiment.

[0015] Figure 2 It is a cross-sectional view of a multiplexer according to an embodiment.

[0016] Figure 3 It is a top view of the filter chip involved in embodiment.

[0017] Figure 4A 1 and 2 are a plan view and a cross-sectional view schematically showing a first example of an elastic wave resonator constituting the multiplexer according to the embodiment.

[0018] Figure 4B FIG. 1 is a cross-sectional view schematically showing a second example of the elastic wave resonator constituting the multiplexer according to the embodiment.

[0019] Figure 4C FIG. 1 is a cross-sectional view schematically showing a third example of the elastic wave resonator constituting the multiplexer according to the embodiment.

[0020] Figure 5 It is a plan view of each layer of a laminate substrate constituting the multiplexer according to the embodiment.

[0021] Figure 6 It is a plan view of each layer of a laminated substrate constituting a multiplexer according to a comparative example.

[0022] Fig. 7A It is an enlarged plan view of the first layer of the multilayer substrate according to the embodiment.

[0023] Figure 7B It is an enlarged plan view of the first layer of the laminated substrate according to the comparative example.

[0024] Fig. 8A is a graph showing the isolation characteristics of the multiplexer according to the embodiment.

[0025] Figure 8B is a graph showing the isolation characteristics of a multiplexer according to a comparative example. DETAILED DESCRIPTION

[0026] The embodiments of the present disclosure are described in detail below using the accompanying drawings. In addition, the embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, configurations of components, and connection methods shown in the following embodiments are examples, and the main purpose is not to limit the present invention.

[0027] In addition, each figure is a schematic diagram that appropriately emphasizes, omits, or adjusts the ratio in order to illustrate the present invention, and is not necessarily strictly illustrated, and sometimes differs from the actual shape, positional relationship, and ratio. In each figure, the same reference numerals are given to substantially the same structure, and repeated descriptions are sometimes omitted or simplified.

[0028] In the circuit configuration of the present disclosure, “connected between A and B” or “connected between A and B” means connected between A and B or connected to both A and B.

[0029] In addition, in the component configuration of the present disclosure, the so-called “component A is configured in series on path B” means that both the signal input terminal and the signal output terminal of component A are connected to the wiring, electrode, or terminal constituting path B.

[0030] In addition, terms such as “parallel” and “perpendicular” indicating the relationship between elements, terms such as “rectangular” indicating the shape of an element, and numerical ranges do not have strict meanings, but refer to substantially equivalent ranges, for example, including errors of several %.

[0031] In addition, in the component configuration of the present disclosure, the so-called "a top view of the main surface" means observing the object by orthographic projection onto the main surface from the z-axis side. The so-called "A is located between B and C" means that at least one of the multiple line segments connecting any point in B and any point in C passes through A.

[0032] In the following embodiments, the passband of an elastic wave device or a filter is defined as a frequency band between two frequencies that are 3 dB higher than the minimum value of insertion loss in the passband.

[0033] In addition, in the present disclosure, frequency band A refers to a frequency band predefined by a standardization organization (e.g., 3GPP (registered trademark), IEEE (Institute of Electrical and Electronics Engineers), etc.) for a communication system constructed using a radio access technology (RAT: Radio Access Technology). In the present embodiment, as a communication system, for example, an LTE (Long Term Evolution) system, a 5G (5th Generation)-NR (New Radio) system, and a WLAN (Wireless Local Area Network) system can be used, but are not limited to these.

[0034] Furthermore, the uplink operating frequency band of frequency band A refers to a frequency range designated for uplink in frequency band A. Furthermore, the downlink operating frequency band of frequency band A refers to a frequency range designated for downlink in frequency band A.

[0035] (Implementation Method)

[0036] [1. Circuit structure of multiplexer]

[0037] Figure 1 1 is a circuit diagram of a multiplexer 1 according to the embodiment. The multiplexer 1 includes filters 10 and 20 , and a common terminal 100 .

[0038] The filter 10 is connected to the common terminal 100, and has, for example, a passband including an uplink operating frequency band of frequency band A. The filter 20 is an example of an elastic wave device, and is connected to the common terminal 100, and has, for example, a passband including a downlink operating frequency band of frequency band A. In the present embodiment, the passband of the filter 10 is located on the lower frequency side than the passband of the filter 20.

[0039] In addition, frequency band A is, for example, frequency band B3 for LTE or frequency band n3 for 5G-NR. The passband of filter 10 includes the uplink operating frequency band (1710-1785 MHz) of frequency band B3 or frequency band n3, and the passband of filter 20 includes the downlink operating frequency band (1805-1880 MHz) of frequency band B3 or frequency band n3.

[0040] like Figure 1 As shown, the filter 10 includes series arm resonators s11 , s12 , s13 , and s14 , parallel arm resonators p11 , p12 , p13 , and p14 , and inductors 31 and 32 .

[0041] The series arm resonators s11 to s14 are elastic wave resonators, respectively, and are arranged in a series arm path connecting the input terminal 110 and the output terminal 101. The parallel arm resonator p11 is an elastic wave resonator, connected between the connection point of the series arm resonators s11 and s12 and the terminal 111. The parallel arm resonator p12 is an elastic wave resonator, connected between the connection point of the series arm resonators s12 and s13 and the terminal 112. The parallel arm resonator p13 is an elastic wave resonator, connected between the connection point of the series arm resonators s13 and s14 and the terminal 112. The parallel arm resonator p14 is an elastic wave resonator, connected between the connection point of the series arm resonator s14 and the input terminal 110 and the terminal 113. The terminal 111 is connected to the ground without an inductor. The terminal 112 is connected to the ground via the inductor 31. The terminal 113 is connected to the ground via the inductor 32.

[0042] With the above-described structure, the filter 10 constitutes a ladder-type bandpass filter.

[0043] In addition, although the series arm resonators s13 and s14 are each composed of three split resonators connected in series, they may also be composed of one resonator. In addition, although the series arm resonators s11 and s12 and the parallel arm resonators p11 to p14 are each composed of two split resonators connected in series, they may also be composed of one resonator.

[0044] The filter 20 is an example of an elastic wave device, and includes series arm resonators s21 , s22 , s23 , and s24 , parallel arm resonators p21 , p22 , p23 , and p24 , and an inductor 33 .

[0045] The series arm resonators s21 to s24 are surface acoustic wave resonators or bulk acoustic wave resonators, respectively, and are arranged in a series arm path connecting the input terminal 102 (first input / output terminal) and the output terminal 120 (second input / output terminal). The series arm resonators s21 and s22 are examples of first series arm resonators, respectively.

[0046] The parallel arm resonator p21 is an example of a first parallel arm resonator, and is connected between a connection point of series arm resonators s21 and s22 and terminal 121. The parallel arm resonator p22 is an example of a second parallel arm resonator, and is connected between a connection point of series arm resonators s22 and s23 and terminal 121. The parallel arm resonator p23 is an example of a third parallel arm resonator, and is connected between a connection point of series arm resonators s23 and s24 and terminal 122. The parallel arm resonator p24 is an example of a third parallel arm resonator, and is connected between a connection point of series arm resonator s24 and output terminal 120 and terminal 122. The parallel arm resonators p21 to p24 are respectively surface acoustic wave resonators or bulk acoustic wave resonators. Terminal 121 is connected to ground without an inductor. Terminal 122 is connected to ground via inductor 33.

[0047] With the above-described structure, the filter 20 constitutes a ladder-type bandpass filter.

[0048] In addition, although the series arm resonator s21 is composed of three divided resonators connected in series, it may be composed of one resonator. In addition, although the series arm resonators s22 to s24 and the parallel arm resonators p21 to p24 are each composed of one resonator, they may be composed of two or more divided resonators.

[0049] Table 1 shows the resonant frequency, anti-resonant frequency, and electrostatic capacitance of the filter 20 .

[0050]

Table 1

[0051]

[0052] [2. Basic structure of multiplexer]

[0053] Figure 2 1 is a cross-sectional view of the multiplexer 1 according to the embodiment. Figure 3 2 is a top view of the filter chip 2 according to the embodiment. Figure 2 yes Figure 3 A cross-sectional view of the multiplexer 1 taken along line II-II.

[0054] like Figure 2 As shown, the multiplexer 1 includes a filter chip 2 and a laminate substrate 40. Figure 3 As shown, the filter chip 2 includes a piezoelectric substrate 50, an IDT (InterDigital Transducer) electrode 54 ( Figure 3 s11 to s14, p11 to p14, s21 to s24, p21 to p24), a common terminal 100, an input terminal 110, an output terminal 120, terminals 111, 112, 113, 121 and 122, and a protruding electrode 70. The common terminal 100, the input terminal 110, the output terminal 120, the terminals 111, 112, 113, 121 and 122 are planar electrodes formed on the principal surface 50a (third principal surface) of the piezoelectric substrate 50.

[0055] In addition, Figure 3 In the diagram, the common terminal 100 , the input terminal 110 , the output terminal 120 , and the terminals 111 , 112 , 113 , 121 , and 122 are not shown, but are arranged on the positive z-axis direction side of the bump electrode 70 .

[0056] In addition, Figure 3 , Figure 5 , Figure 6 , Fig. 7A as well as Figure 7B In the figure, the protruding electrode 70 connected to the common terminal 100 is recorded as the protruding electrode 70 (100), the protruding electrode 70 connected to the input terminal 110 is recorded as the protruding electrode 70 (110), the protruding electrode 70 connected to the output terminal 120 is recorded as the protruding electrode 70 (120), and the protruding electrodes 70 connected to the terminals 111, 112, 113, 121 and 122 are recorded as the protruding electrodes 70 (111), 70 (112), 70 (113), 70 (121) and 70 (122) respectively.

[0057] exist Figure 3In the figure, the IDT electrode and the planar electrode constituting the filter 10 are arranged above the filter chip 2 (on the positive side of the y-axis), and the IDT electrode and the planar electrode constituting the filter 20 are arranged below the filter chip 2 (on the negative side of the y-axis).

[0058] In addition, Figure 2 as well as Figure 3 In the example, each series arm resonator and each parallel arm resonator are surface acoustic wave resonators, but each series arm resonator and each parallel arm resonator may also be a bulk acoustic wave resonator. In addition, the detailed structure of the surface acoustic wave resonator and the bulk acoustic wave resonator is described by using FIG. 4A to FIG. 4C to explain.

[0059] The piezoelectric substrate 50 is an example of a second substrate, and has main surfaces 50a (third main surface) and 50b facing each other, and is a substrate having piezoelectricity. Figures 4A to 4C to explain.

[0060] The laminated substrate 40 is an example of a first substrate. Figure 2 As shown, the laminate substrate 40 has main surfaces 40a and 40b facing each other, and has a plurality of dielectric layers L1, L2 and L3. The laminate substrate 40 is configured so that the main surface 40a faces the main surface 50a. As the laminate substrate 40, for example, a low temperature co-fired ceramic (LTCC) substrate, a high temperature co-fired ceramic (HTCC) substrate, a component-embedded substrate, a substrate having a redistribution layer (RDL), or a printed substrate can be used, which has a laminated structure of a plurality of dielectric layers L1 to L3.

[0061] The stacked substrate 40 has, from the main surface 40a toward the main surface 40b, an electrode layer L41 which is a surface of the dielectric layer L1 on the positive direction side of the z-axis, an electrode layer L42 which is a surface of the dielectric layer L2 on the positive direction side of the z-axis, an electrode layer L43 which is a surface of the dielectric layer L3 on the positive direction side of the z-axis, and an electrode layer L44 which is a surface of the dielectric layer L3 on the negative direction side of the z-axis, and a conductor pattern including a planar electrode is formed on each electrode layer.

[0062] [3. Basic structures of series-arm resonators and parallel-arm resonators]

[0063] Next, the basic structure of each series arm resonator and each parallel arm resonator constituting the multiplexer 1 will be described. Figure 4A1 is a top view and a cross-sectional view schematically showing a first example of an elastic wave resonator constituting the multiplexer 1 according to the embodiment. In this figure, a basic structure of the elastic wave resonator constituting the multiplexer 1 is illustrated. Figure 4A The elastic wave resonator 60 shown is for explaining a typical structure of an elastic wave resonator constituting the multiplexer 1 , and the number and length of electrode fingers constituting the electrodes are not limited thereto.

[0064] The elastic wave resonator 60 is composed of a piezoelectric substrate 50 and comb-shaped electrodes 60a and 60b. Figure 4A As shown in (a), a pair of comb-shaped electrodes 60a and 60b facing each other are formed on the piezoelectric substrate 50. The comb-shaped electrode 60a is composed of a plurality of electrode fingers 61a parallel to each other, and a bus bar electrode 62a connecting one ends of the plurality of electrode fingers 61a to each other. In addition, the comb-shaped electrode 60b is composed of a plurality of electrode fingers 61b parallel to each other, and a bus bar electrode 62b connecting one ends of the plurality of electrode fingers 61b to each other. The plurality of electrode fingers 61a and 61b are formed along a direction orthogonal to the direction of propagation of the elastic wave (X-axis direction). The bus bar electrode 62a and the bus bar electrode 62b are arranged opposite to each other with the electrode fingers 61a and 61b sandwiched therebetween. The comb-shaped electrodes 60a and 60b constitute the IDT electrode 54.

[0065] Here, when filter 20 according to the present embodiment performs electromechanical conversion using surface acoustic waves, IDT electrode 54 is a functional electrode. Alternatively, elastic wave resonator 60 may include reflectors at both ends of IDT electrode 54 in the elastic wave propagation direction (X-axis direction).

[0066] like Figure 4A As shown in (b) of FIG. 8 , the IDT electrode 54 has a stacked structure of, for example, an adhesion layer 540 and a main electrode layer 542 .

[0067] The adhesion layer 540 is a layer for improving the adhesion between the piezoelectric substrate 50 and the main electrode layer 542, and for example, Ti can be used as a material. For example, Al containing 1% Cu can be used as a material for the main electrode layer 542. The protective layer 55 is formed to cover the comb-shaped electrodes 60a and 60b. The protective layer 55 is a layer for the purpose of protecting the main electrode layer 542 from the external environment, adjusting the frequency-temperature characteristics, and improving moisture resistance, and for example, is a dielectric film with silicon dioxide as a main component.

[0068] In addition, the materials constituting the adhesion layer 540, the main electrode layer 542 and the protective layer 55 are not limited to the above materials. Furthermore, the IDT electrode 54 may not be the above-mentioned stacked structure. The IDT electrode 54 may be composed of a metal or alloy such as Ti, Al, Cu, Pt, Au, Ag, Pd, etc., or may be composed of a plurality of stacked bodies, each of which is composed of the above-mentioned metal or alloy. In addition, the protective layer 55 may not be formed.

[0069] Next, the stacked structure of the piezoelectric substrate 50 will be described.

[0070] like Figure 4A As shown in (c), the piezoelectric substrate 50 includes a high-acoustic-velocity supporting substrate 51, a low-acoustic-velocity film 52, and a piezoelectric film 53, and has a structure in which the high-acoustic-velocity supporting substrate 51, the low-acoustic-velocity film 52, and the piezoelectric film 53 are stacked in this order.

[0071] The piezoelectric film 53 includes, for example, a θ°Y-cut X-propagation LiTaO3 piezoelectric single crystal or a piezoelectric ceramic (a lithium tantalate single crystal or ceramic cut on a plane with the X-axis as the center axis and the axis rotated by θ° from the Y-axis as the normal line, and a single crystal or ceramic in which surface acoustic waves propagate in the X-axis direction). In addition, the material of the piezoelectric single crystal used as the piezoelectric film 53 and the cutting angle θ can be appropriately selected according to the required specifications of each filter.

[0072] The high acoustic velocity support substrate 51 is a substrate that supports the low acoustic velocity film 52, the piezoelectric film 53, and the IDT electrode 54. The high acoustic velocity support substrate 51 is also a substrate that makes the acoustic velocity of the body wave in the high acoustic velocity support substrate 51 higher than the elastic waves such as the surface wave and the boundary wave propagating in the piezoelectric film 53, and functions to confine the surface acoustic wave in the portion where the piezoelectric film 53 and the low acoustic velocity film 52 are stacked, and does not leak to the lower part of the high acoustic velocity support substrate 51. As the material of the high acoustic velocity support substrate 51, for example, piezoelectrics such as aluminum nitride, lithium tantalate, lithium niobate, and quartz, alumina, sapphire, magnesium oxide, silicon nitride, silicon carbide, zirconium oxide, cordierite, mullite, steatite, forsterite, spinel, ceramics such as sialon, dielectrics such as aluminum oxide, silicon oxynitride, DLC (diamond-like carbon), and diamond, or semiconductors such as silicon, or materials containing the above materials as main components can be used. In addition, the spinel contains an aluminum compound containing one or more elements selected from Mg, Fe, Zn, Mn, etc. and oxygen. Examples of the spinel include MgAl2O4, FeAl2O4, ZnAl2O4, and MnAl2O4.

[0073] The low-acoustic-velocity film 52 is a film that makes the acoustic velocity of the body wave in the low-acoustic-velocity film 52 lower than that of the body wave propagating in the piezoelectric film 53, and is disposed between the piezoelectric film 53 and the high-acoustic-velocity supporting substrate 51. Due to this structure and the property that the energy of the elastic wave is essentially concentrated in the medium with a low acoustic velocity, it is possible to suppress the leakage of the surface acoustic wave energy to the outside of the IDT electrode 54. As the material of the low-acoustic-velocity film 52, for example, a dielectric such as glass, silicon oxide, silicon oxynitride, lithium oxide, tantalum oxide, or a compound in which fluorine, carbon, or boron is added to silicon oxide, or a material having the above materials as a main component can be used.

[0074] In addition, the stacked structure of the piezoelectric substrate 50 can significantly improve the Q value at the resonant frequency and the anti-resonant frequency compared to the conventional structure using a single-layer piezoelectric substrate. That is, an elastic wave resonator with a high Q value can be formed, and thus a filter with a small insertion loss can be formed using the elastic wave resonator.

[0075] In addition, the high-acoustic-velocity support substrate 51 may have a structure in which a support substrate and a high-acoustic-velocity film are stacked, and the acoustic velocity of the body wave propagated by the high-acoustic-velocity film becomes higher than that of elastic waves such as surface waves and boundary waves propagated in the piezoelectric film 53. In this case, as a material of the high-acoustic-velocity film, the same material as that of the high-acoustic-velocity support substrate 51 can be used. In addition, as a material of the support substrate, for example, piezoelectrics such as aluminum nitride, lithium tantalate, lithium niobate, and quartz, alumina, sapphire, magnesium oxide, silicon nitride, silicon carbide, zirconium oxide, ceramics such as cordierite, mullite, steatite, and forsterite, dielectrics such as diamond and glass, semiconductors such as silicon and gallium nitride, or resins, or materials having the above materials as main components can be used.

[0076] In this specification, the term "main component of a material" refers to a component that accounts for more than 50% by weight of the material. The main component may be present in any state of single crystal, polycrystalline, or amorphous, or in a mixed state thereof.

[0077] Figure 4B FIG. 2 is a cross-sectional view schematically showing a second example of an elastic wave resonator constituting the multiplexer 1 according to the embodiment. Figure 4A In the elastic wave resonator 60 shown in FIG. 1 , an example is shown in which the IDT electrode 54 is formed on the piezoelectric substrate 50 having the piezoelectric film 53. Figure 4B As shown, the substrate on which the IDT electrode 54 is formed may be a single-layer piezoelectric single crystal substrate 57 including a piezoelectric layer.

[0078] The piezoelectric single crystal substrate 57 is made of, for example, a piezoelectric single crystal of LiNbO 3 . The elastic wave resonator according to this example is made of a piezoelectric single crystal substrate 57 of LiNbO 3 , an IDT electrode 54 , and a protective layer 58 formed on the piezoelectric single crystal substrate 57 and the IDT electrode 54 .

[0079] The stacked structure, material, cutting angle, and thickness of the piezoelectric film 53 and the piezoelectric single crystal substrate 57 can be appropriately changed according to the required characteristics of the multiplexer 1. Even an elastic wave resonator using a LiTaO3 piezoelectric substrate having a cutting angle other than the above-mentioned cutting angle can achieve the same effect as the elastic wave resonator 60 using the piezoelectric film 53.

[0080] In addition, the piezoelectric substrate forming the IDT electrode 54 may also have a structure in which a supporting substrate, an energy confinement layer, and a piezoelectric film are stacked in sequence. The IDT electrode 54 is formed on the piezoelectric film. The piezoelectric film may be, for example, a LiTaO3 piezoelectric single crystal or a piezoelectric ceramic. The supporting substrate is a substrate that supports the piezoelectric film, the energy confinement layer, and the IDT electrode 54.

[0081] The energy confinement layer includes one or more layers, and the speed of the body acoustic wave propagating in at least one of the layers is greater than the speed of the elastic wave propagating near the piezoelectric film. For example, the energy confinement layer can also be a stacked structure of a low-acoustic velocity layer and a high-acoustic velocity layer. The low-acoustic velocity layer is a film in which the sound speed of the body wave in the low-acoustic velocity layer becomes low compared to the sound speed of the elastic wave propagating in the piezoelectric film. The high-acoustic velocity layer is a film in which the sound speed of the body wave in the high-acoustic velocity layer becomes high compared to the sound speed of the elastic wave propagating in the piezoelectric film. In addition, the supporting substrate can also be used as a high-acoustic velocity layer.

[0082] Alternatively, the energy confinement layer may be an acoustic impedance layer having a structure in which low acoustic impedance layers having relatively low acoustic impedance and high acoustic impedance layers having relatively high acoustic impedance are alternately stacked.

[0083] Here, electrode parameters of the IDT electrode constituting elastic wave resonator 60 will be described.

[0084] The wavelength of the elastic wave resonator is composed of Figure 4A The repetition period of the plurality of electrode fingers 61a or 61b of the IDT electrode 54 shown in (b), i.e., the wavelength λ, is defined. In addition, the electrode finger pitch is 1 / 2 of the wavelength λ, and is defined by (W+S) when the line width of the electrode fingers 61a and 61b constituting the comb-shaped electrodes 60a and 60b is set to W and the space width between the adjacent electrode fingers 61a and 61b is set to S.

[0085] In the IDT electrode 54, when the intervals between adjacent electrode fingers are not constant, the electrode finger pitch of the IDT electrode 54 is defined by the average electrode finger pitch of the IDT electrode 54. When the total number of electrode fingers 61a and 61b included in the IDT electrode 54 is Ni and the center-to-center distance between the electrode fingers at one end and the electrode fingers at the other end of the IDT electrode 54 in the elastic wave propagation direction is Di, the average electrode finger pitch of the IDT electrode 54 is defined as Di / (Ni-1).

[0086] also, Figure 4C FIG. 1 is a cross-sectional view schematically showing a third example of the elastic wave resonator constituting the multiplexer 1 according to the embodiment. Figure 4C In FIG. 1 , a bulk acoustic wave resonator is shown as an elastic wave resonator of the multiplexer 1. As shown in the figure, the bulk acoustic wave resonator has, for example, a support substrate 65, a lower electrode 66, a piezoelectric layer 67, and an upper electrode 68, and has a structure in which the support substrate 65, the lower electrode 66, the piezoelectric layer 67, and the upper electrode 68 are stacked in this order.

[0087] The support substrate 65 is a substrate, for example, a silicon substrate, for supporting the lower electrode 66, the piezoelectric layer 67, and the upper electrode 68. In addition, the support substrate 65 is provided with a cavity in a region in contact with the lower electrode 66. Thus, the piezoelectric layer 67 can vibrate freely.

[0088] The lower electrode 66 is an example of a third plane electrode, and is formed on one surface of the support substrate 65. The upper electrode 68 is an example of a fourth plane electrode, and is formed on one surface of the support substrate 65. The lower electrode 66 and the upper electrode 68 are made of, for example, Al containing 1% Cu.

[0089] The piezoelectric layer 67 is an example of a piezoelectric thin film, and is formed between the lower electrode 66 and the upper electrode 68. The piezoelectric layer 67 includes, for example, at least one of ZnO (zinc oxide), AlN (aluminum nitride), PZT (lead zirconate titanate), KN (potassium niobate), LN (lithium niobate), LT (lithium tantalate), quartz, and LiBO (lithium borate) as a main component.

[0090] The bulk acoustic wave resonator having the above-mentioned stacked structure generates resonance by applying electric energy between the lower electrode 66 and the upper electrode 68 to induce bulk acoustic waves in the piezoelectric layer 67. The bulk acoustic waves generated by the bulk acoustic wave resonator propagate between the lower electrode 66 and the upper electrode 68 in a direction perpendicular to the film surface of the piezoelectric layer 67. In other words, the bulk acoustic wave resonator is a resonator using bulk acoustic waves.

[0091] Here, when the filter 20 according to the present embodiment performs electromechanical conversion using bulk acoustic waves, the lower electrode 66, the piezoelectric layer 67, and the upper electrode 68 are functional electrodes. In addition, the support substrate 65 may be used as the first substrate instead of the piezoelectric substrate 50.

[0092] [4. Joining structure of filter chip and laminated substrate]

[0093] Next, use Figure 3 as well as Figures 5 to 7B The bonding structure between the filter chip 2 and the multilayer substrate 40 will be described.

[0094] like Figure 3 As shown, in the filter chip 2, the parallel arm resonator p21 (first parallel arm resonator) has a portion of the piezoelectric substrate 50 and an IDT electrode 54p. The IDT electrode 54p is an example of the second functional electrode and is one of the IDT electrodes 54. In addition, the series arm resonator s21 (first series arm resonator) has the other portion of the piezoelectric substrate 50 and an IDT electrode 54s. The IDT electrode 54s is an example of the first functional electrode and is one of the IDT electrodes 54.

[0095] in addition, Figure 1 The output terminal 101 and the input terminal 102 shown in the figure are planar electrodes similar to the common terminal 100 on the main surface 50a. The common terminal 100, the input terminal 110, the output terminal 120, the terminals 111, 112, 113, 121 and 122 are respectively connected with the protruding electrodes 70. Figure 3 As shown, the bump electrode 70 ( 121 ) is an example of a first bump electrode, and is connected to the IDT electrode 54 p .

[0096] Figure 5 FIG. 4 is a top view of each layer of the multilayer substrate 40 constituting the multiplexer 1 according to the embodiment. Figure 5 As shown, the laminate substrate 40 has planar electrodes 410, 420, 430, 440, 441, 442, 443, and 444, and a plurality of via-hole conductors 81. Figure 5 The circles (circles) shown in (a) to (c) indicate via-hole conductors 81 penetrating from the surface on the principal surface 40 a side to the surface on the principal surface 40 b side in any of the dielectric layers L1 to L3 .

[0097] exist Figure 5(a) shows the electrode layout of the electrode layer L41 formed on the side of the main surface 40a of the dielectric layer L1. The protruding electrode 70 provided on the filter chip 2 is bonded to the planar electrode of the electrode layer L41. The planar electrode 410 formed on the electrode layer L41 is an example of the first planar electrode and is bonded to the protruding electrodes 70 (121) and 70 (111). The planar electrode 410 connected to the protrusion 70 (121) is connected to the planar electrode 420 of the electrode layer L42 below the electrode layer L41 through a plurality of via conductors 81.

[0098] exist Figure 5 (b) shows the electrode layout of the electrode layer L42 formed on the main surface 40a side of the dielectric layer L2. The planar electrode 420 is connected to the planar electrode 430 of the electrode layer L43 below the electrode layer L42 through a plurality of via conductors 81.

[0099] exist Figure 5 (c) shows the electrode layout of the electrode layer L43 formed on the main surface 40a side of the dielectric layer L3. The planar electrode 430 is connected to the planar electrode 440 of the electrode layer L44 below the electrode layer L43 through a plurality of via conductors 81.

[0100] exist Figure 5 (d) shows the electrode layout of the electrode layer L44 formed on the side of the main surface 40b of the dielectric layer L3. The planar electrode 440 formed on the electrode layer L44 is an example of a second planar electrode, and is connected to the planar electrode 430 formed on the electrode layer L43 via a plurality of via conductors 81, and is connected to the ground. In addition, the planar electrode 441 formed on the electrode layer L44 is connected to the protruding electrode 70 (100) of the electrode layer L41 via the electrode layers L42 and L43. In addition, the planar electrode 442 formed on the electrode layer L44 is connected to the protruding electrode 70 (110) of the electrode layer L41 via the electrode layers L42 and L43. In addition, the planar electrode 443 formed on the electrode layer L44 is connected to the protruding electrode 70 (120) of the electrode layer L41 via the electrode layers L42 and L43. In addition, the planar electrode 444 formed on the electrode layer L44 is connected to the protruding electrode 70 (122) of the electrode layer L41 via the electrode layers L42 and L43. The planar electrodes 440, 441, 442, 443 and 444 formed on the electrode layer L44 are external connection terminals for connecting the multiplexer 1 to an external substrate arranged face to face with the main surface 40b.

[0101] The number of via-hole conductors 81 connecting the planar electrodes 410 and 420 is the largest among the number of via-hole conductors 81 connecting one planar electrode of the electrode layer L41 and one planar electrode of the electrode layer L42. Thus, the inductance component between the planar electrodes 410 and 420 can be reduced.

[0102] The number of via-hole conductors 81 connecting the planar electrodes 420 and 430 is the largest among the number of via-hole conductors 81 connecting one planar electrode of the electrode layer L42 and one planar electrode of the electrode layer L43. Thus, the inductance component between the planar electrodes 420 and 430 can be reduced.

[0103] The number of via-hole conductors 81 connecting the planar electrodes 430 and 440 is the largest among the number of via-hole conductors 81 connecting one planar electrode of the electrode layer L43 and one planar electrode of the electrode layer L44. Thus, the inductance component between the planar electrodes 430 and 440 can be reduced.

[0104] This can reduce the inductance component from the planar electrode 440 as the external connection terminal to the bump 70 (121), and as a result, can improve the steepness of the filter characteristics.

[0105] In addition, the planar electrode 410 joined to the protruding electrode 70 (121) may be configured not on the electrode layer L41 which is the outermost layer of the stacked substrate 40, but on the first dielectric layer among the multiple dielectric layers L1 to L3 that form the planar electrode. The planar electrode 440 may be configured not on the electrode layer L44 which is the outermost layer of the stacked substrate 40, but on the second dielectric layer which is closer to the main surface 40b than the first dielectric layer among the multiple dielectric layers L1 to L3 that form the planar electrode.

[0106] Figure 6 1 is a plan view of each layer of a laminate substrate 40 constituting a multiplexer according to a comparative example. The multiplexer according to the comparative example is different from the multiplexer 1 according to the embodiment only in that the planar electrode 410 of the electrode layer L41 is replaced with a planar electrode 510 .

[0107] exist Figure 6 (a) shows the electrode layout of the electrode layer L41. The protruding electrode 70 provided on the filter chip 2 is bonded to the planar electrode of the electrode layer L41. The planar electrode 510 formed on the electrode layer L41 is bonded to the protruding electrodes 70 (121) and 70 (111). In addition, Figure 6 The electrode layouts of (b) to (d) are respectively Figure 5 The electrode layouts of (b) to (d) are the same.

[0108] Fig. 7A : is an enlarged plan view of the electrode layer L41 of the laminated substrate 40 according to the embodiment. Figure 7B It is an enlarged plan view of the electrode layer L41 of the multilayer substrate according to the comparative example. Fig. 7A Yes Figure 5(a) is an enlarged top view of region VIIA. Figure 7B Yes Figure 6 An enlarged top view of region VIIB of (a).

[0109] Here, if Fig. 7A As shown, in the filter 20 involved in this embodiment, when looking down at the main surface 40a, the protruding electrode 70 (121) is located between two via-hole conductors 81a and 81b among the multiple via-hole conductors 81 connected to the planar electrode 410. In addition, the protruding electrode 70 (121) is connected between the parallel arm resonator p21 of the filter 20 and the ground. As shown in Table 1, the parallel arm resonator p21 has the highest resonance frequency among the multiple parallel arm resonators constituting the filter 20. In addition, the so-called multiple parallel arm resonators constituting the filter 20 are parallel arm resonators that contribute to forming the passband of the filter 20, and are specifically defined as parallel arm resonators whose anti-resonance frequencies are located within the passband of the filter 20.

[0110] Furthermore, the parallel arm resonator p21 has the highest resonance frequency among the plurality of parallel arm resonators constituting the filter 20 . In other words, the parallel arm resonator p21 has the smallest electrode finger pitch of the IDT electrode among the plurality of parallel arm resonators constituting the filter 20 .

[0111] In a ladder-type elastic wave filter, if parasitic inductance is generated in the path connecting the parallel arm resonator and the ground, the resonant frequency of the parallel arm resonator changes. When the electrostatic capacitance of the parallel arm resonator is set to Cp and the above-mentioned parasitic inductance is set to Lp, the larger the parasitic inductance Lp, the more the resonant frequency of the parallel arm resonator (=1 / 2π√(LpCp)) changes to the low-frequency side, and the interval between the resonant frequency and the anti-resonant frequency will expand. As a result, the attenuation slope on the low-frequency side of the passband becomes slower, and the attenuation near the low-frequency side of the passband will deteriorate. In particular, the parallel arm resonator with the highest resonant frequency among the multiple parallel arm resonators constituting the elastic wave filter determines the attenuation and steepness near the low-frequency side of the passband. Therefore, if the resonant frequency of the parallel arm resonator with the highest resonant frequency changes to the low-frequency side, the attenuation characteristics near the low-frequency side of the passband of the elastic wave filter will be greatly deteriorated. In the multiplexer 1 and the filter 20 according to the present embodiment, no intentional inductor is connected between the parallel arm resonator p21 having the highest resonance frequency among the plurality of parallel arm resonators and the ground. The so-called intentional inductor includes a sheet-shaped inductor and an inductor including a conductor coil formed on an electrode layer constituting a laminate substrate.

[0112] In the multiplexer involved in the comparative example, Figure 7BAs shown in FIG. 1 , when the main surface 40a is viewed from above, the protruding electrode 70 (121) is not located between two via-hole conductors 81 among the plurality of via-hole conductors 81 connected to the planar electrode 510. Therefore, if the bonding position of the protruding electrode 70 (121) is shifted, the distance between the protruding electrode 70 (121) and the via-hole conductor 81 closest thereto changes, and thus the parasitic inductance generated between the protruding electrode 70 (121) and the planar electrode 440 connected to the ground of the electrode layer L44 changes significantly.

[0113] On the other hand, in the case of the multiplexer 1 according to the embodiment, as Fig. 7A As shown in FIG. 1 , the protruding electrode 70 (121) is located between two via-hole conductors 81a and 81b among the plurality of via-hole conductors 81. Therefore, even if the bonding position of the protruding electrode 70 (121) changes, if the distance between the protruding electrode 70 (121) and the via-hole conductor 81a increases, the distance between the protruding electrode 70 (121) and the via-hole conductor 81b decreases. Thus, the change in the parasitic inductance specified by the parallel connection of the parasitic inductance generated in the path connecting the protruding electrode 70 (121) and the via-hole conductor 81a and the parasitic inductance generated in the path connecting the protruding electrode 70 (121) and the via-hole conductor 81b can be suppressed.

[0114] Fig. 8A is a graph showing the isolation characteristics of the multiplexer 1 according to the embodiment. Figure 8B 2 is a graph showing the isolation characteristic of the multiplexer according to the comparative example. The multiplexer according to the comparative example is different from the multiplexer 1 according to the embodiment only in that the planar electrode 410 of the filter 20 is replaced with a planar electrode 510 .

[0115] exist Fig. 8A as well as Figure 8B Two types of waveform data (solid line and dotted line) are shown respectively. Fig. 8A as well as Figure 8B In both cases, the solid line waveform data is data obtained when the position of the bump electrode 70 ( 121 ) is moved by +30 μm in the positive direction of the y-axis with respect to the dotted line waveform data.

[0116] In the multiplexer 1 according to the present embodiment, the isolation of the passband of the filter 10 is 0.001 % when there is no position shift ( Fig. 8A The dashed line data) is 58.5dB, and in the case of position offset ( Fig. 8A The solid line data is 58.0dB, which is a degradation of 0.5dB.

[0117] On the other hand, in the multiplexer according to the comparative example, the isolation of the passband of the filter 10 is 0.0447 W in the case where there is no position shift ( Figure 8BThe dashed line data) is 58.4dB, and in the case of position offset ( Figure 8B The solid line data is 54.1dB, which is a degradation of 4.3dB.

[0118] According to the above, when the filter chip 2 is flip-chip bonded to the laminated substrate 40, the multiplexer 1 according to the embodiment can suppress the change of the parasitic inductance generated between the parallel arm resonator and the ground even if there is a shift in the bonding position of the protruding electrode for connecting the parallel arm resonator with the highest resonance frequency to the ground, thereby improving the isolation on the high-frequency side of the passband of the filter 10. In other words, the filter 20 according to the embodiment can improve the attenuation characteristics near the low-frequency side of the passband of the filter 20 compared to the filter according to the comparative example. Therefore, the filter 20 and the multiplexer 1 in which the degradation of the pass characteristics is suppressed can be provided.

[0119] In addition, in the filter 20 involved in this embodiment, if Figure 1 As shown, the parallel arm resonator p21 is connected to the path connecting the input terminal 102 and the series arm resonator s22 and the terminal 121, and the parallel arm resonator p22 is connected to the path connecting the output terminal 120 and the series arm resonator s22 and the terminal 121. That is, Figure 3 As shown, the parallel arm resonators p21 and p22 are connected to the ground via a common bump electrode 70 (121).

[0120] Regarding the resonant frequency of the parallel arm resonator (=1 / 2π√(LpCp)), the larger the electrostatic capacitance Cp is, the more likely the resonant frequency will change even with a slight change in the parasitic inductance Lp. Therefore, in order to suppress the deviation of the resonant frequency, it is effective to reduce the electrostatic capacitance Cp. However, in order to achieve the miniaturization of the filter chip, it is necessary to reduce the number of protruding electrodes 70 connected to the ground, which creates the need to connect multiple parallel arm resonators to a common protruding electrode 70. As a result, in the multiplexer involved in the past (comparative example), the synthetic electrostatic capacitance Cp of the parallel arm resonators p21 and p22 connected to one protruding electrode 70 becomes larger, and even with a slight change in the parasitic inductance Lp, the resonant frequency changes significantly, resulting in a problem in which it is impossible to take into account both the miniaturization of the filter chip and the suppression of characteristic changes.

[0121] In contrast, according to the multiplexer 1 and the filter 20 of the present embodiment, even if the combined electrostatic capacitance Cp of the parallel arm resonators p21 and p22 connected to one protruding electrode 70 (121) increases, the variation of the parasitic inductance Lp caused by the positional displacement of the protruding electrode 70 (121) can be suppressed, and thus the variation of the attenuation characteristics on the lower frequency side than the passband of the filter 20 defined by the parallel arm resonator p21 having the highest resonance frequency among the plurality of parallel arm resonators can be suppressed. Therefore, it is possible to provide a compact filter 20 and a multiplexer 1 in which the degradation of the passband characteristics is suppressed.

[0122] In addition, in the multiplexer 1 according to the present embodiment, Fig. 7A As shown, when looking down at the main surface 40a, the protruding electrode 70 (121) is located between two via conductors 81a and 81b among the multiple via conductors 81 connected to the planar electrode 410, and is located between two via conductors 81c and 81d, and the two via conductors 81c and 81d are located on an imaginary straight line intersecting the imaginary line segment connecting the two via conductors 81a and 81b.

[0123] Accordingly, when the bonding position of the protruding electrode 70 (121) is viewed from above the main surface 40a, it is possible to suppress changes in parasitic inductance not only when it is offset in the direction of an imaginary line connecting the via-hole conductors 81a and 81b, but also when it is offset in the direction of an imaginary line connecting the via-hole conductors 81c and 81d.

[0124] In addition, if Figure 3As shown in FIG. 1 , in the multiplexer 1 according to the present embodiment, eight protruding electrodes 70 are arranged on the main surface 50a. Among the eight protruding electrodes 70, the protruding electrode 70 (113) (second protruding electrode) and the protruding electrode 70 (120) (third protruding electrode) are arranged at both ends of the outer side of the piezoelectric substrate 50 when viewed from the main surface 50a. On the other hand, the protruding electrode 70 (121) is located between the protruding electrode 70 (113) and the protruding electrode 70 (120) when viewed from the main surface 50a. In other words, the protruding electrode 70 (121) is arranged in the area except the corner of the piezoelectric substrate 50. Since the protruding electrode arranged in the corner of the piezoelectric substrate 50 is far away from the center of the piezoelectric substrate 50, the position variation distance of the protruding electrode becomes large with respect to the position deviation in the rotation direction of the piezoelectric substrate 50, and the variation of the parasitic inductance becomes large. Therefore, by arranging the protruding electrode 70 (121) connected to the parallel arm resonator p21 having the highest resonance frequency among the multiple parallel arm resonators in an area other than the corners of the piezoelectric substrate 50, that is, an area close to the center of the piezoelectric substrate 50, it is possible to effectively suppress not only the characteristic changes caused by the positional deviation in the x-axis and y-axis directions, but also the characteristic changes caused by the positional deviation in the rotational direction.

[0125] Furthermore, in the filter 20 according to the present embodiment, as shown in Table 1, the parallel arm resonator p21 has the smallest electrostatic capacitance among the plurality of parallel arm resonators.

[0126] The parallel arm resonator p21 having the highest resonance frequency among the plurality of parallel arm resonators has the highest impedance on the low-frequency side in the passband. In the parallel arm resonator, the higher the impedance, the lower the insertion loss of the passband. Therefore, by minimizing the electrostatic capacitance of the parallel arm resonator p21, the impedance can be increased, and the insertion loss of the passband can be improved.

[0127] The electrostatic capacitance of the surface acoustic wave resonator is proportional to (number of pairs × cross width) of the IDT electrode. Therefore, as a method of identifying a parallel arm resonator having the smallest electrostatic capacitance among a plurality of parallel arm resonators, the magnitudes of (number of pairs × cross width) of the IDT electrode may be compared.

[0128] In the filter 20 according to the present embodiment, the parallel arm resonator p23 includes a piezoelectric substrate 50, an IDT electrode (third functional electrode: Figure 3 In the figure, it is shown as p23), and a bump electrode 70 (122) (the fourth bump electrode) connected to the IDT electrode. Figure 5As shown, the stacked substrate 40 has a planar electrode 411 (5th planar electrode) arranged on the electrode layer L41 and joined to the protruding electrode 70 (122), a planar electrode 444 (6th planar electrode) arranged on the electrode layer L44 and connected to the ground, and an inductor 33 (arranged on the electrode layer L42) connected between the planar electrode 411 and the planar electrode 444.

[0129] The ground of the parallel arm resonator p23 is separated from the ground of the parallel arm resonator p21 having the highest resonance frequency in the multiplexer 1, and is connected to the ground via the protruding electrode 70 (122) different from the protruding electrode 70 (121) and the inductor 33. By connecting the inductor 33 to the parallel arm resonator p23, the interval between the resonance frequency and the anti-resonance frequency of the parallel arm resonator p23 is widened, and the attenuation pole based on the resonance frequency of the parallel arm resonator p23 can be located on the low-frequency side within the passband of the filter 10. Therefore, the filter 20 having improved attenuation characteristics over a wide frequency band on the low-frequency side of the passband of the filter 20 can be provided.

[0130] In addition, the parallel arm resonator p24 is connected to the protruding electrode 70 (122) together with the parallel arm resonator p23, so the combined electrostatic capacitance of the parallel arm resonators p23 and p24 becomes larger, and the inductance value for obtaining a given resonant frequency can be reduced. As a result, the line width of the inductor 33 formed in the laminated substrate 40 can be widened, so that the deviation of the inductance value of the inductor 33 can be suppressed. Therefore, a small filter 20 with improved attenuation characteristics and a small multiplexer 1 with improved isolation characteristics can be provided.

[0131] [5. Effects, etc.]

[0132] As described above, the filter 20 according to the present embodiment includes a series arm resonator s21 arranged in a series arm path connecting the input terminal 102 and the output terminal 120, a plurality of parallel arm resonators p21 to p24 connected between the series arm path and the ground, a laminated substrate 40 having main surfaces 40a and 40b facing each other and having a plurality of dielectric layers, a piezoelectric substrate 50 having a main surface 50a arranged face to face with the main surface 40a, and a protruding electrode 70 (121) arranged on the main surface 50a, wherein the series arm resonator s21 includes a first functional electrode arranged on the main surface 50a, and the parallel arm resonator p21 among the plurality of parallel arm resonators p21 to p24 includes a second functional electrode arranged on the main surface 50a, and the protruding electrode 70 (121) is arranged on the main surface 50a. The protruding electrode 70 (121) is connected to the second functional electrode, and the laminated substrate 40 has a planar electrode 410 which is arranged in the first dielectric layer among the plurality of dielectric layers and is bonded to the protruding electrode 70 (121), a planar electrode 440 which is arranged in the second dielectric layer among the plurality of dielectric layers and is closer to the main surface 40b than the first dielectric layer and is connected to the ground, and a plurality of via conductors 81 connecting the planar electrode 410 and the planar electrode 440. When the main surface 40a is viewed from above, the protruding electrode 70 (121) is located between two via conductors 81a and 81b among the plurality of via conductors 81 connected to the planar electrode 410, and the parallel arm resonator p21 has the highest resonance frequency among the plurality of parallel arm resonators p21 to p24.

[0133] Accordingly, when the filter chip 2 is flip-chip bonded to the laminated substrate 40, even if there is a shift in the bonding position of the protruding electrode 70 (121) for connecting the parallel arm resonator p21 with the highest resonance frequency to the ground, the change of the parasitic inductance generated between the parallel arm resonator p21 and the ground can be suppressed. As a result, the attenuation characteristics on the lower frequency side than the passband of the filter 20 can be improved, and the isolation characteristics on the higher frequency side of the passband of the filter 10 in the multiplexer 1 can be improved. Therefore, the filter 20 and the multiplexer 1 that suppress the degradation of the pass characteristics can be provided.

[0134] Furthermore, for example, in the filter 20 , the second substrate is the piezoelectric substrate 50 , and the first functional electrode and the second functional electrode are IDT electrodes, respectively.

[0135] This can suppress degradation of the transmission characteristics of the filter 20 that performs electromechanical conversion using surface acoustic waves.

[0136] Furthermore, for example, in the filter 20 , the first functional electrode and the second functional electrode each include a lower electrode 66 , a piezoelectric layer 67 , and an upper electrode 68 in this order from the main surface 40 a .

[0137] This can suppress degradation of the transmission characteristics of the filter 20 that performs electromechanical conversion using bulk acoustic waves.

[0138] The filter 20 according to the present embodiment includes a series arm resonator s21 arranged in a series arm path connecting an input terminal 102 and an output terminal 120, a plurality of parallel arm resonators p21 to p24 connected between the series arm path and ground, a laminated substrate 40 having main surfaces 40a and 40b facing each other and having a plurality of dielectric layers, a piezoelectric substrate 50 having a main surface 50a arranged face to face with the main surface 40a, and a protruding electrode 70 (121) arranged on the main surface 50a, wherein the series arm resonator s21 includes a first functional electrode arranged on the main surface 50a, and the parallel arm resonator p21 among the plurality of parallel arm resonators p21 to p24 includes a second functional electrode arranged on the main surface 50a, and the protruding electrode 70 (121) is connected to the second functional electrode. Electrode connection, the stacked substrate 40 has a planar electrode 410 arranged in a first dielectric layer among a plurality of dielectric layers and bonded to the protruding electrode 70 (121), a planar electrode 440 arranged in a second dielectric layer among a plurality of dielectric layers on the main surface 40b side of the first dielectric layer and connected to the ground, and a plurality of via conductors 81 connecting the planar electrode 410 and the planar electrode 440. When the main surface 40a is viewed from above, the protruding electrode 70 (121) is located between two via conductors 81a and 81b among the plurality of via conductors 81 connected to the planar electrode 410. The first functional electrode and the second functional electrode are IDT electrodes, respectively. The parallel arm resonator p21 has the smallest electrode finger pitch of the IDT electrode among the plurality of parallel arm resonators p21 to p24.

[0139] Accordingly, when the filter chip 2 is flip-chip bonded to the laminated substrate 40, even if there is a shift in the bonding position of the protruding electrode 70 (121) for connecting the parallel arm resonator p21 with the highest resonance frequency to the ground, the change of the parasitic inductance generated between the parallel arm resonator p21 and the ground can be suppressed. As a result, the attenuation characteristics on the lower frequency side than the passband of the filter 20 can be improved, and the isolation characteristics on the higher frequency side of the passband of the filter 10 in the multiplexer 1 can be improved. Therefore, the filter 20 and the multiplexer 1 that suppress the degradation of the pass characteristics can be provided.

[0140] In addition, for example, the filter 20 includes parallel arm resonators p21 and p22, the parallel arm resonator p21 is connected to the path connecting the input terminal 102 and the series arm resonator s22 and the protruding electrode 70 (121), and the parallel arm resonator p22 is connected to the path connecting the output terminal 120 and the series arm resonator s22 and the protruding electrode 70 (121).

[0141] Thus, even if the combined electrostatic capacitance Cp of the parallel arm resonators p21 and p22 connected to one protruding electrode 70 (121) increases, the change of the parasitic inductance Lp caused by the positional deviation of the protruding electrode 70 (121) can be suppressed. Thus, the change of the attenuation characteristics on the lower frequency side than the passband of the filter 20 defined by the parallel arm resonator p21 having the highest resonance frequency among the plurality of parallel arm resonators can be suppressed. Therefore, a small filter 20 can be provided in which the degradation of the passband characteristics is suppressed.

[0142] Furthermore, for example, in the filter 20 , the planar electrode 410 is disposed on the main surface 40 a .

[0143] Furthermore, for example, in the filter 20 , the planar electrode 440 is disposed on the main surface 40 b .

[0144] Furthermore, for example, in the filter 20 , the planar electrode 440 is an external connection terminal.

[0145] In addition, for example, in the filter 20, when looking down at the main surface 40a, the protruding electrode 70 (121) is located between two via-hole conductors 81a and 81b among the multiple via-hole conductors 81 connected to the planar electrode 410, and is located between two via-hole conductors 81c and 81d, and the two via-hole conductors 81c and 81d are located on an imaginary straight line intersecting with an imaginary line segment connecting the two via-hole conductors 81a and 81b.

[0146] Accordingly, not only can the change in parasitic inductance be suppressed when the bonding position of the protruding electrode 70 (121) is shifted in the direction of an imaginary line connecting the via-hole conductors 81a and 81b when viewed from above the main surface 40a, but also when the bonding position of the protruding electrode 70 (121) is shifted in the direction of an imaginary line connecting the via-hole conductors 81c and 81d.

[0147] In addition, for example, in the filter 20, a plurality of protruding electrodes 70 including a protruding electrode 70 (121) are arranged on the main surface 40a, and the protruding electrode 70 (113) and the protruding electrode 70 (120) among the plurality of protruding electrodes 70 are arranged at two end portions of the outer side of the piezoelectric substrate 50 when viewed from above the main surface 40a, and the protruding electrode 70 (121) is located between the protruding electrode 70 (113) and the protruding electrode 70 (120) when viewed from above the main surface 40a.

[0148] Accordingly, the protruding electrode 70 (121) connected to the parallel arm resonator p21 having the highest resonance frequency among the plurality of parallel arm resonators p21 to p24 is arranged in an area other than the corners of the piezoelectric substrate 50, that is, in an area close to the center of the piezoelectric substrate 50. Thus, it is possible to effectively suppress not only the characteristic variation caused by the positional deviation of the protruding electrode 70 (121) in the x-axis and y-axis directions, but also the characteristic variation caused by the positional deviation of the protruding electrode 70 (121) in the rotation direction.

[0149] Furthermore, for example, in the filter 20 , the parallel arm resonator p21 has the smallest electrostatic capacitance among the plurality of parallel arm resonators p21 to p24 .

[0150] The parallel arm resonator p21 having the highest resonance frequency among the plurality of parallel arm resonators p21 to p24 has the lowest impedance on the low-frequency side in the passband. In the parallel arm resonator, the higher the impedance, the lower the insertion loss of the passband. Accordingly, by minimizing the electrostatic capacitance of the parallel arm resonator p21, the impedance can be increased, and the insertion loss of the passband of the filter 20 can be improved.

[0151] In addition, for example, in the filter 20, the parallel arm resonator p23 has a piezoelectric substrate 50, an IDT electrode arranged on the main surface 50a, and a protruding electrode 70 (122) arranged on the main surface 50a and connected to the above-mentioned IDT electrode. The stacked substrate 40 also has a planar electrode 411 arranged on a dielectric layer closest to the main surface 40a among a plurality of dielectric layers and bonded to the protruding electrode 70 (122), a planar electrode 444 arranged on a dielectric layer closest to the main surface 40b among a plurality of dielectric layers and connected to the ground, and an inductor 33 connected between the planar electrode 411 and the planar electrode 444.

[0152] According to this, by connecting the inductor 33 to the parallel arm resonator p23, the interval between the resonant frequency and the antiresonant frequency of the parallel arm resonator p23 is widened, and the attenuation pole based on the resonant frequency of the parallel arm resonator p23 can be located on the low-frequency side within the passband of the filter 10. Therefore, the attenuation characteristics can be improved over a wide frequency band on the low-frequency side than the passband of the filter 20.

[0153] Furthermore, the multiplexer 1 according to the present embodiment includes a common terminal 100 , the filter 20 described above whose input terminal 102 is connected to the common terminal 100 , and a filter 10 connected to the common terminal 100 and having a passband located on the lower frequency side than the filter 20 .

[0154] Thus, it is possible to provide the multiplexer 1 in which degradation of the isolation characteristic on the high-frequency side of the passband of the filter 10 is suppressed.

[0155] (Other Embodiments)

[0156] The elastic wave device and multiplexer according to the present invention are described above by enumerating the embodiments, but the present invention is not limited to the above embodiments. Modifications obtained by applying various modifications thought of by a person skilled in the art to the above embodiments within the scope of the main purpose of the present invention, and various devices incorporating the elastic wave device and multiplexer according to the present invention are also included in the present invention.

[0157] Furthermore, for example, in the elastic wave devices and multiplexers according to the above-described embodiments, matching elements such as inductors and capacitors, and switch circuits may be connected between the components.

[0158] The resonant frequency and antiresonant frequency described in the above embodiments are derived by, for example, bringing an RF probe into contact with two input and output electrodes of an elastic wave resonator to measure reflection characteristics.

[0159] Features of the elastic wave device and the multiplexer described based on the above-mentioned embodiment and modified examples are described below.

[0160] <1>

[0161] An elastic wave device comprising:

[0162] a first series arm resonator arranged in a series arm path connecting the first input / output terminal and the second input / output terminal;

[0163] a plurality of parallel arm resonators connected between the series arm paths and ground;

[0164] The first substrate has a first main surface and a second main surface facing each other and has a plurality of dielectric layers;

[0165] a second substrate having a third main surface arranged face to face with the first main surface; and

[0166] a first protruding electrode disposed on the third main surface;

[0167] The first series arm resonator includes a first functional electrode disposed on the third main surface.

[0168] A first parallel arm resonator among the plurality of parallel arm resonators includes a second functional electrode disposed on the third main surface,

[0169] The first protruding electrode is connected to the second functional electrode.

[0170] The first substrate has:

[0171] a first planar electrode disposed in a first dielectric layer among the plurality of dielectric layers and joined to the first protruding electrode;

[0172] a second planar electrode disposed in a second dielectric layer located closer to the second main surface than the first dielectric layer among the plurality of dielectric layers and connected to ground; and

[0173] A plurality of via conductors connect the first planar electrode and the second planar electrode,

[0174] When the first main surface is viewed in plan, the first bump electrode is located between two via conductors among the plurality of via conductors connected to the first planar electrode.

[0175] The first parallel arm resonator has the highest resonance frequency among the plurality of parallel arm resonators.

[0176] <2>

[0177] according to <1> The elastic wave device, wherein:

[0178] The second substrate has piezoelectricity,

[0179] The first functional electrode and the second functional electrode are IDT electrodes respectively.

[0180] <3>

[0181] according to <1> The elastic wave device, wherein:

[0182] The first functional electrode and the second functional electrode each include a third planar electrode, a piezoelectric film, and a fourth planar electrode in order from the third main surface.

[0183] <4>

[0184] An elastic wave device comprising:

[0185] a first series arm resonator arranged in a series arm path connecting the first input / output terminal and the second input / output terminal;

[0186] a plurality of parallel arm resonators connected between the series arm paths and ground;

[0187] The first substrate has a first main surface and a second main surface facing each other and has a plurality of dielectric layers;

[0188] a second substrate having a third main surface arranged face to face with the first main surface; and

[0189] a first protruding electrode disposed on the third main surface;

[0190] The first series arm resonator includes a first functional electrode disposed on the third main surface.

[0191] A first parallel arm resonator among the plurality of parallel arm resonators includes a second functional electrode disposed on the third main surface,

[0192] The first protruding electrode is connected to the second functional electrode.

[0193] The first substrate has:

[0194] a first planar electrode disposed in a first dielectric layer among the plurality of dielectric layers and joined to the first protruding electrode;

[0195] a second planar electrode disposed in a second dielectric layer located closer to the second main surface than the first dielectric layer among the plurality of dielectric layers and connected to ground; and

[0196] A plurality of via conductors connect the first planar electrode and the second planar electrode,

[0197] When the first main surface is viewed in plan, the first bump electrode is located between two via conductors among the plurality of via conductors connected to the first planar electrode.

[0198] The first functional electrode and the second functional electrode are IDT electrodes respectively.

[0199] The first parallel arm resonator has the smallest electrode finger pitch of an IDT electrode among the plurality of parallel arm resonators.

[0200] <5>

[0201] according to <1> to <4> The elastic wave device as described in any one of the preceding claims, wherein:

[0202] The plurality of parallel arm resonators include the first parallel arm resonator and the second parallel arm resonator.

[0203] The first parallel arm resonator is connected to a path connecting the first input / output terminal and the first series arm resonator and the first bump electrode.

[0204] The second parallel arm resonator is connected to a path connecting the second input-output terminal and the first series arm resonator and the first bump electrode.

[0205] <6>

[0206] according to <1> to <5> The elastic wave device as described in any one of the preceding claims, wherein:

[0207] The first planar electrode is disposed on the first main surface.

[0208] <7>

[0209] according to <1> to <6> The elastic wave device as described in any one of the preceding claims, wherein:

[0210] The second planar electrode is disposed on the second main surface.

[0211] <8>

[0212] according to <7> The elastic wave device, wherein:

[0213] The second planar electrode is an external connection terminal.

[0214] <9>

[0215] according to <1> to <8> The elastic wave device as described in any one of the preceding claims, wherein:

[0216] In a plan view of the first main surface, the first bump electrode is located between two via conductors among the plurality of via conductors connected to the first planar electrode and between two via conductors located on an imaginary straight line intersecting an imaginary line segment connecting the two via conductors.

[0217] <10>

[0218] according to <1> to <9> The elastic wave device as described in any one of the preceding claims, wherein:

[0219] A plurality of protruding electrodes including the first protruding electrode are arranged on the third main surface,

[0220] The second and third protruding electrodes among the plurality of protruding electrodes are arranged at both ends of the outer side of the second substrate in a plan view of the third main surface.

[0221] The first bump electrode is located between the second bump electrode and the third bump electrode in a plan view of the third main surface.

[0222] <11>

[0223] according to <1> to <10> The elastic wave device as described in any one of the preceding claims, wherein:

[0224] The first parallel arm resonator has the smallest electrostatic capacitance among the plurality of parallel arm resonators.

[0225] <12>

[0226] according to <1> to <11> The elastic wave device as described in any one of the preceding claims, wherein:

[0227] The plurality of parallel arm resonators include the first parallel arm resonator and the third parallel arm resonator.

[0228] The third parallel arm resonator has:

[0229] the second substrate;

[0230] a third functional electrode disposed on the third main surface; and

[0231] a fourth protruding electrode disposed on the third main surface and connected to the third functional electrode;

[0232] The first substrate further comprises:

[0233] a fifth planar electrode disposed on the dielectric layer closest to the first main surface among the plurality of dielectric layers and joined to the fourth protruding electrode;

[0234] a sixth planar electrode disposed on the dielectric layer closest to the second main surface among the plurality of dielectric layers and connected to the ground; and

[0235] The inductor is connected between the fifth planar electrode and the sixth planar electrode.

[0236] <13>

[0237] A multiplexer having:

[0238] Common terminal;

[0239] <1> to <12> In the elastic wave device described in any one of the preceding claims, the first input / output terminal is connected to the common terminal; and

[0240] The filter is connected to the common terminal and has a passband located on a lower frequency side than the elastic wave device.

[0241] Industrial Applicability

[0242] The present invention can be widely used in communication equipment such as mobile phones as a low-loss and high-attenuation elastic wave device or multiplexer applicable to a multi-band frequency standard.

[0243] Description of Reference Numerals

[0244] 1 multiplexer;

[0245] 2 filter chips;

[0246] 10, 20 filters;

[0247] 31, 32, 33 inductors;

[0248] 40-layer laminated substrate;

[0249] 40a, 40b, 50a, 50b main surfaces;

[0250] 50 piezoelectric substrate;

[0251] 51 high acoustic velocity support substrate;

[0252] 52 low sound velocity membrane;

[0253] 53 piezoelectric film;

[0254] 54, 54p, 54s IDT electrodes;

[0255] 55, 58 protective layer;

[0256] 57 piezoelectric single crystal substrate;

[0257] 60 elastic wave resonator;

[0258] 60a, 60b comb-shaped electrodes;

[0259] 61a, 61b electrode fingers;

[0260] 62a, 62b bus bar electrodes;

[0261] 65 support base plate;

[0262] 66 lower electrode;

[0263] 67 piezoelectric layer;

[0264] 68 upper electrode;

[0265] 70, 70(100), 70(110), 70(111), 70(112), 70(113), 70(120), 70(121), 70(122) raised electrodes;

[0266] 81, 81a, 81b, 81c, 81d via conductors;

[0267] 100 common terminals;

[0268] 101, 120 output terminals;

[0269] 102, 110 input terminals;

[0270] 111, 112, 113, 121, 122 terminals;

[0271] 410, 411, 420, 430, 440, 441, 442, 443, 444, 510 planar electrodes;

[0272] 540 close contact layer;

[0273] 542 main electrode layer;

[0274] L1, L2, L3 dielectric layers;

[0275] L41, L42, L43, L44 electrode layers;

[0276] p11, p12, p13, p14, p21, p22, p23, p24 parallel arm resonators;

[0277] s11, s12, s13, s14, s21, s22, s23, s24 series arm resonators.

Claims

1. An elastic wave device comprising: a first series arm resonator arranged in a series arm path connecting the first input / output terminal and the second input / output terminal; a plurality of parallel arm resonators connected between the series arm paths and ground; The first substrate has a first main surface and a second main surface facing each other and has a plurality of dielectric layers; a second substrate having a third main surface arranged face to face with the first main surface; and a first protruding electrode disposed on the third main surface; The first series arm resonator includes a first functional electrode disposed on the third main surface. A first parallel arm resonator among the plurality of parallel arm resonators includes a second functional electrode disposed on the third main surface, The first protruding electrode is connected to the second functional electrode. The first substrate has: a first planar electrode disposed in a first dielectric layer among the plurality of dielectric layers and joined to the first protruding electrode; a second planar electrode disposed in a second dielectric layer located closer to the second main surface than the first dielectric layer among the plurality of dielectric layers and connected to ground; and A plurality of via conductors connect the first planar electrode and the second planar electrode, When the first main surface is viewed in plan, the first bump electrode is located between two via conductors among the plurality of via conductors connected to the first planar electrode. The first parallel arm resonator has the highest resonance frequency among the plurality of parallel arm resonators.

2. The elastic wave device according to claim 1, wherein: The second substrate has piezoelectricity, The first functional electrode and the second functional electrode are IDT electrodes respectively.

3. The elastic wave device according to claim 1, wherein: The first functional electrode and the second functional electrode each include a third planar electrode, a piezoelectric film, and a fourth planar electrode in order from the third main surface.

4. An elastic wave device comprising: a first series arm resonator arranged in a series arm path connecting the first input / output terminal and the second input / output terminal; a plurality of parallel arm resonators connected between the series arm paths and ground; The first substrate has a first main surface and a second main surface facing each other and has a plurality of dielectric layers; a second substrate having a third main surface arranged face to face with the first main surface; and a first protruding electrode disposed on the third main surface; The first series arm resonator includes a first functional electrode disposed on the third main surface. A first parallel arm resonator among the plurality of parallel arm resonators includes a second functional electrode disposed on the third main surface, The first protruding electrode is connected to the second functional electrode. The first substrate has: a first planar electrode disposed in a first dielectric layer among the plurality of dielectric layers and joined to the first protruding electrode; a second planar electrode disposed in a second dielectric layer located closer to the second main surface than the first dielectric layer among the plurality of dielectric layers and connected to ground; and A plurality of via conductors connect the first planar electrode and the second planar electrode, When the first main surface is viewed in plan, the first bump electrode is located between two via conductors among the plurality of via conductors connected to the first planar electrode. The first functional electrode and the second functional electrode are IDT electrodes respectively. The first parallel arm resonator has the smallest electrode finger pitch of an IDT electrode among the plurality of parallel arm resonators.

5. The elastic wave device according to any one of claims 1 to 4, wherein: The plurality of parallel arm resonators include the first parallel arm resonator and the second parallel arm resonator. The first parallel arm resonator is connected to a path connecting the first input / output terminal and the first series arm resonator and the first bump electrode. The second parallel arm resonator is connected to a path connecting the second input-output terminal and the first series arm resonator and the first bump electrode.

6. The elastic wave device according to any one of claims 1 to 5, wherein: The first planar electrode is disposed on the first main surface.

7. The elastic wave device according to any one of claims 1 to 6, wherein: The second planar electrode is disposed on the second main surface.

8. The elastic wave device according to claim 7, wherein: The second planar electrode is an external connection terminal.

9. The elastic wave device according to any one of claims 1 to 8, wherein: In a plan view of the first main surface, the first bump electrode is located between two via conductors among the plurality of via conductors connected to the first planar electrode and between two via conductors located on an imaginary straight line intersecting an imaginary line segment connecting the two via conductors.

10. The elastic wave device according to any one of claims 1 to 9, wherein: A plurality of protruding electrodes including the first protruding electrode are arranged on the third main surface, The second and third protruding electrodes among the plurality of protruding electrodes are arranged at both ends of the outer side of the second substrate in a plan view of the third main surface. The first bump electrode is located between the second bump electrode and the third bump electrode in a plan view of the third main surface.

11. The elastic wave device according to any one of claims 1 to 10, wherein: The first parallel arm resonator has the smallest electrostatic capacitance among the plurality of parallel arm resonators.

12. The elastic wave device according to any one of claims 1 to 11, wherein: The plurality of parallel arm resonators include the first parallel arm resonator and the third parallel arm resonator. The third parallel arm resonator has: the second substrate; a third functional electrode disposed on the third main surface; and a fourth protruding electrode disposed on the third main surface and connected to the third functional electrode; The first substrate further comprises: a fifth planar electrode disposed on the dielectric layer closest to the first main surface among the plurality of dielectric layers and joined to the fourth protruding electrode; a sixth planar electrode disposed on the dielectric layer closest to the second main surface among the plurality of dielectric layers and connected to the ground; and The inductor is connected between the fifth planar electrode and the sixth planar electrode.

13. A multiplexer comprising: Common terminal; The elastic wave device according to any one of claims 1 to 12, wherein the first input / output terminal is connected to the common terminal; and The filter is connected to the common terminal and has a passband located on a lower frequency side than the elastic wave device.

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