Elastic wave device, filter, and multiplexer

Abstract

To provide an elastic wave device capable of size reduction.SOLUTION: An elastic wave device includes a substrate 10, an elastic wave element 52 provided on the substrate 10 and having an electrode, a first metal layer provided on the substrate 10, formed of the same material as at least one layer of the electrode, and electrically connected to the electrode, a second metal layer provided on the first metal layer, and a third metal layer provided on the substrate 10, not having the second metal layer, and having the first metal layer.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to acoustic wave devices, filters and multiplexers. [Background technology]

[0002] A circuit having a resistor connected in series or parallel to an acoustic wave element is known (e.g., Patent Document 1). It is known to mount a chip on which an acoustic wave element is provided on a substrate, and to electrically connect the resistor provided on the substrate to the acoustic wave element (e.g., Patent Documents 2 and 3). It is known to provide an acoustic wave element and a resistor on a substrate (e.g., Patent Document 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-3542 A [Patent Document 2] Japanese Patent Application Publication No. 8-274575 [Patent Document 3] Japanese Patent Application Publication No. 9-93077 [Patent Document 4] Japanese Patent Application Publication No. 9-260994 Summary of the Invention [Problem to be solved by the invention]

[0004] When an acoustic wave element is mounted on a substrate and a resistor provided on the substrate is electrically connected to the acoustic wave element using bonding wires or bumps as in Patent Documents 2 and 3, the acoustic wave device becomes large. Patent Document 4 does not disclose a method for connecting the acoustic wave element and the resistor.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide a compact design. [Means for solving the problem]

[0006] The present invention is an acoustic wave device comprising: a substrate; an acoustic wave element provided on the substrate and having an electrode; a first metal layer provided on the substrate, made of the same material as at least one layer of the electrode and electrically connected to the electrode; a second metal layer provided on the first metal layer; and a conductive layer provided on the substrate, having the first metal layer but not the second metal layer.

[0007] The aforementioned configuration may further include a wiring electrically connecting the conductive layer and the acoustic wave element, the wiring including the first metal layer and the second metal layer.

[0008] In the above configuration, the second metal layer may have a lower resistivity than the first metal layer.

[0009] In the above configuration, the second metal layer may be thicker than the first metal layer.

[0010] In the above configuration, a cross-sectional area of ​​the first metal layer in the conductive layer perpendicular to the extension direction of the wiring can be smaller than a cross-sectional area of ​​the first metal layer in the wiring in the perpendicular direction.

[0011] The present invention is an acoustic wave device comprising: a substrate; an acoustic wave element provided on the substrate and having an electrode; a first wiring provided on the substrate and having a first metal layer made of the same material as at least one layer of the electrode and electrically connected to the electrode; a second wiring provided on the substrate and having the first metal layer and separated from the first wiring; and a conductive layer provided on the substrate, provided between the first wiring and the second wiring, having both ends electrically connected to the first wiring and the second wiring, respectively, and having a resistivity greater than that of the first metal layer.

[0012] In the above configuration, the first wiring and the second wiring may include a second metal layer provided on the first metal layer and having a resistivity lower than that of the conductive layer.

[0013] The present invention is an acoustic wave device comprising: a substrate; an acoustic wave element provided on the substrate and having an electrode; a wiring provided on the substrate and having a first metal layer made of the same material as at least one layer of the electrode and electrically connected to the electrode; and a conductive layer provided on the substrate and electrically connected to the electrode via the wiring, made of the same material as at least a portion of the first metal layer, and having a cross-sectional area perpendicular to the extension direction of the wiring that is smaller than the cross-sectional area of ​​the wiring perpendicular to the extension direction.

[0014] In the above configuration, in a connection region between the conductive layer and the wiring, a cross-sectional area of ​​the first metal layer perpendicular to the extending direction may be gradually reduced from the wiring to the conductive layer.

[0015] In the above configuration, the elastic wave element includes a lower electrode provided on the substrate, a piezoelectric layer provided on the lower electrode, and an upper electrode provided on the piezoelectric layer, and the electrode can be the lower electrode or the upper electrode.

[0016] The present invention also relates to a filter including the above acoustic wave device.

[0017] The above configuration may include an input terminal, an output terminal, a first capacitor and a second capacitor connected in series between the input terminal and the output terminal, and an inductor having one end connected to a node between the first capacitor and the second capacitor and the other end connected to ground, wherein the elastic wave element is connected in parallel to the first capacitor and the second capacitor between the input terminal and the output terminal, and the conductive layer is connected in parallel to the first capacitor and the second capacitor between the input terminal and the output terminal, and is connected in series or in parallel to the elastic wave element.

[0018] The present invention is a multiplexer including the above filter. Effect of the Invention

[0019] According to the present invention, miniaturization is possible. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a circuit diagram of a filter in accordance with a first embodiment. [Diagram 2] FIG. 2(a) is a plan view of the acoustic wave device in accordance with the first embodiment, and FIG. 2(b) is a cross-sectional view taken along line AA of FIG. 2(a). [Diagram 3] 3A and 3B are cross-sectional views of acoustic wave devices according to a second embodiment and a first modified example thereof. [Figure 4] 4(a) to 4(c) are plan views of the vicinity of a resistive region of an acoustic wave device according to a third embodiment and first and second modifications thereof. [Diagram 5] 5A and 5B are cross-sectional views of the resistive region and its surroundings of acoustic wave devices according to third and fourth modifications of the third embodiment. [Figure 6] FIG. 6(a) is a plan view of an acoustic wave device in accordance with a fourth embodiment, and FIG. 6(b) is a cross-sectional view taken along line AA of FIG. 6(a). [Figure 7] FIG. 7 is a plan view of an acoustic wave device in accordance with a fifth embodiment. [Figure 8] FIG. 8 is a cross-sectional view taken along line AA in FIG. [Figure 9] 9(a) and 9(b) are circuit diagrams of filters according to the sixth embodiment and a first modified example thereof. [Figure 10] FIG. 10 is a circuit diagram of a triplexer in accordance with the seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0022] The first embodiment is an example in which an acoustic wave element and a resistor used in a filter are provided on the same substrate. FIG. 1 is a circuit diagram of a filter in which the acoustic wave device of the first embodiment is used. As shown in FIG. 1, in a filter 100, capacitors C1 and C2 are connected in series between an input terminal Tin and an output terminal Tout. Between the input terminal Tin and the output terminal Tout, an acoustic wave element 52 and resistors R1 and R2 are connected in parallel to the capacitors C1 and C2. The node between the capacitors C1 and C2 is a node N1. One end of an inductor L1 is connected to the node N1 and the other end is connected to a ground terminal Tg, and the inductor L1 is shunt-connected to a path between the input terminal Tin and the output terminal Tout. The capacitor C1 and the acoustic wave element 52 are connected at the node N2, and the capacitor C2 and the acoustic wave element 52 are connected at the node N3.

[0023] Filter 100 is a high-pass filter or a low-pass filter, which passes signals in a pass band among high-frequency signals (for example, frequencies of 0.5 GHz to 10 GHz) input to input terminal Tin to output terminal Tout and suppresses signals of other frequencies. An attenuation pole caused by the resonance frequency of acoustic wave element 52 is provided between the pass band and an attenuation pole caused by capacitors C1, C2, inductor L1, and the capacitance of the acoustic wave resonator. This improves the steepness between the pass band and the attenuation region. Furthermore, resistors R1 and R2 are connected in series to acoustic wave element 52. This makes it possible to make the attenuation pole caused by capacitors C1, C2, inductor L1, and the capacitance of the acoustic wave resonator steeper.

[0024] 1, acoustic wave element 52, resistors R1 and R2 are provided on the same substrate as acoustic wave device 60. Acoustic wave element 52, resistors R1 and R2, and capacitors C1 and C2 may be provided on the same substrate as acoustic wave device 62.

[0025] Fig. 2(a) is a plan view of the acoustic wave device in accordance with the first embodiment, and Fig. 2(b) is a cross-sectional view taken along line AA in Fig. 2(a). The thickness direction of the substrate 10 is the Z direction, the arrangement direction of the pads 21a and 21b is the X direction, and the direction perpendicular to the X direction and the Z direction is the Y direction.

[0026] As shown in FIG. 2(a) and FIG. 2(b), in the acoustic wave device 60 of the first embodiment, the acoustic wave element 52 is a piezoelectric thin film resonator. In the acoustic wave element 52, a recess is provided on the upper surface of the substrate 10, and a gap 11 is provided in the recess. A lower electrode 12 is provided on the gap 11. The lower electrode 12 includes a lower layer 12a and an upper layer 12b. A piezoelectric layer 14 is provided on the lower electrode 12. An upper electrode 16 is provided on the piezoelectric layer 14. The upper electrode 16 includes a lower layer 16a and an upper layer 16b. A region where the lower electrode 12 and the upper electrode 16 overlap with each other, sandwiching the piezoelectric layer 14, is a resonance region 50. The piezoelectric layer 14 in the resonance region 50 is excited by an acoustic wave in a longitudinal vibration mode or a thickness shear mode. In a plan view, the resonance region 50 is the same as or smaller than the gap 11. The upper surface of the substrate 10 may be flat, and the lower electrode 12 may be provided above the upper surface of the substrate 10 with a gap 11 therebetween. Instead of the gap 11, an acoustic reflection film in which high impedance films and low impedance films are alternately laminated may be provided.

[0027] The lower layer 12a and the upper layer 12b are drawn out from the resonance region 50 in the +X direction, and the metal layer 13 includes the lower layer 12a and the upper layer 12b. The lower layer 16a and the upper layer 16b are drawn out from the resonance region 50 in the -X direction, and the metal layer 17 includes the lower layer 16a and the upper layer 16b. A metal layer 18 is provided on the metal layers 13 and 17 outside the resonance region 50. The metal layers 17 and 18 form a wiring 20a and a pad 21a. The wiring 20a electrically connects the acoustic wave element 52 and the resistor R1, and electrically connects the resistor R1 and the pad 21a. The metal layer 13 and the metal layer 18 form a wiring 20b and a pad 21b. The wiring 20b electrically connects the acoustic wave element 52 and the resistor R2, and electrically connects the resistor R2 and the pad 21b. The regions where metal layer 18 is not provided on metal layers 17 and 13 are resistor regions 30a and 30b, respectively. Metal layers 17 and 13 in resistor regions 30a and 30b form resistors R1 and R2, respectively.

[0028] The substrate 10 is an insulating substrate or a semiconductor substrate such as a silicon substrate, a sapphire substrate, a spinel substrate, an alumina substrate, a quartz substrate, a glass substrate, a ceramic substrate, or a GaAs substrate. The lower electrode 12, the upper electrode 16, and the metal layers 13 and 17 are single-layer films or laminated films mainly composed of, for example, ruthenium (Ru), chromium (Cr), aluminum (Al), titanium (Ti), copper (Cu), silver (Ag), gold (Au), molybdenum (Mo), tungsten (W), tantalum (Ta), platinum (Pt), rhodium (Rh), or iridium (Ir). The lower layer 12a and the upper layer 12b are, for example, a chromium layer and a ruthenium layer, respectively, and the lower layer 16a and the upper layer 16b are, for example, a ruthenium layer and a chromium layer, respectively. The lower electrode 12 and the metal layer 13 may be formed of one metal layer or three or more metal layers, and the upper electrode 16 and the metal layer 17 may be formed of one metal layer or three or more metal layers. The metal layer 18 is mainly composed of an element having a low resistivity, such as copper, aluminum, gold or silver.

[0029] Table 1 shows the resistivity of conductive materials. The volume ratio to Ru is expressed as the volume required to obtain the same resistance value when the cross-sectional area perpendicular to the direction of current flow is constant, with Ru set to 1. The volume ratio to Ru is the same as the planar area required to obtain the same resistance value when the cross-sectional area is constant, with Ru set to 1. [Table 1]

[0030] The piezoelectric layer 14 is aluminum nitride (AlN), zinc oxide (ZnO), zirconium titanate (PZT), lead titanate (PbTiO3), lithium tantalate (LiTaO3), lithium niobate (LiNbO3), or quartz. The piezoelectric layer 14 may be polycrystalline or single crystal. The piezoelectric layer 14 may be mainly composed of aluminum nitride, for example, and may contain other elements to improve resonance characteristics or piezoelectricity. For example, the piezoelectricity of the piezoelectric layer 14 is improved by using scandium (Sc), two elements of a group 2 element and a group 4 element, or two elements of a group 2 element and a group 5 element as an additive element. This improves the effective electromechanical coupling coefficient of the piezoelectric thin film resonator. The group 2 element is, for example, calcium (Ca), magnesium (Mg), strontium (Sr), or zinc (Zn). The group 4 element is, for example, titanium, zirconium (Zr), or hafnium (Hf). The Group 5 element is, for example, tantalum, niobium (Nb) or vanadium (V). Furthermore, the piezoelectric layer 14 may be mainly composed of aluminum nitride and may contain boron (B).

[0031] The thickness T1 of the metal layers 13 and 17 is, for example, 0.01 μm to 0.5 μm. The thickness T2 of the metal layer 18 is, for example, 0.2 μm to 2 μm. The widths W1 and W2 of the resistance regions 30a and 30b in the X and Y directions are, for example, 5 μm to 1000 μm.

[0032] According to the first embodiment, the wiring 20a includes a metal layer 17 (first metal layer) that is integral with the lower layer 16a and the upper layer 16b of the upper electrode 16, and a metal layer 18 (second metal layer) that is provided on the metal layer 17. The wiring 20b includes a metal layer 13 (first metal layer) that is integral with the lower layer 12a and the upper layer 12b of the lower electrode 12, and a metal layer 18 that is provided on the metal layer 13. The resistor R1 (conductive layer) is provided on the substrate 10 with the piezoelectric layer 14 sandwiched therebetween, and the resistor R2 (conductive layer) is provided on the substrate 10. The resistors R1 and R2 are electrically connected to the acoustic wave element 52 via the wiring 20a and 20b, respectively. The resistor R1 does not include the metal layer 18 but includes the metal layer 17, and the resistor R2 does not include the metal layer 18 but includes the metal layer 13.

[0033] In this way, by using the same metal layers 13 and 17 for the resistors R1 and R2 as the lower electrode 12 or the upper electrode 16, the acoustic wave device can be made smaller in size. Also, the number of manufacturing steps can be reduced.

[0034] The metal layer 17 of the resistor R1 may be made of the same material as at least one metal layer of the upper electrode 16, and the metal layer 13 of the resistor R2 may be made of the same material as the metal layer of the lower electrode 12. For example, in the resistor R1, the metal layer 17 may have the upper layer 16b and may not have the lower layer 16a. In the resistor R2, the metal layer 13 may have the lower layer 12a and may not have the upper layer 12b. When the upper electrode 16 (or the lower electrode 12) has multiple metal layers, the resistance value of the resistor R1 (or R2) can be increased by making the metal layer with the highest resistivity the metal layer 17 (or 13) of the resistor R1 (or R2). In addition, the metal layer 13 is directly connected to the lower electrode 12, and the metal layer 17 is directly connected to the upper electrode 16.

[0035] Metal layer 18 does not have to be provided between resistors R1 and R2 and acoustic wave element 52. Wiring 20a including metal layers 17 and 18 electrically connects resistor R1 and acoustic wave element 52, thereby reducing the resistance between resistor R1 and acoustic wave element 52. Wiring 20b including metal layers 13 and 18 electrically connects resistor R2 and acoustic wave element 52, thereby reducing the resistance between resistor R2 and acoustic wave element 52.

[0036] From the viewpoint of lowering the resistance value of the wirings 20a and 20b and raising the resistance value of the resistors R1 and R2, the resistivity of the metal layer 18 is preferably lower than that of the metal layers 13 and 17, more preferably 0.8 times or less, and even more preferably 0.5 times or less, of the resistivity of the metal layers 13 and 17. As shown in Table 1, when the main components of the metal layers 13 and 17 are ruthenium and chromium, and the main component of the metal layer 18 is gold, the resistivity of the metal layer 18 is approximately 1 / 3 of the resistivity of the metal layers 13 and 17. In order not to make the resistance values ​​of the lower electrode 12 and the upper electrode 16 too high, the resistivity of the metal layers 13 and 17 is preferably 20 times or less than the resistivity of the metal layer 18.

[0037] When the main component of metal layers 13 and 17 is ruthenium, silver, copper, aluminum, molybdenum, or tungsten can be used as the main component of metal layer 18 in addition to gold. Note that a certain metal layer containing a certain element as its main component means that the certain element is contained in the certain metal layer to an extent that the magnitude relationship of the resistivity does not change, and the content of the certain element in the certain metal layer is, for example, 50 atomic % or more, 80 atomic % or more, or 90 atomic % or more.

[0038] From the viewpoint of lowering the resistance value of the wirings 20a and 20b and raising the resistance value of the resistors R1 and R2, the thickness T2 of the metal layer 18 is preferably larger than the thickness T1 of the metal layers 13 and 17, more preferably 1.5 times or more, and more preferably 2 times or more of the thickness T1. The thickness T2 of the metal layer 18 is, for example, 50 times or less the thickness T1 of the metal layers 13 and 17. EXAMPLES

[0039] 3(a) and 3(b) are cross-sectional views of acoustic wave devices according to Example 2 and Modification 1 thereof. As shown in FIG. 3(a), in Example 2, in a resistive region 30a, the metal layer 17 is removed, and a resistive layer 22 is provided on a piezoelectric layer 14. Both ends of the resistive layer 22 in the X direction are electrically connected to the wiring 20a. In a resistive region 30b, the metal layer 13 is removed, and the resistive layer 22 is provided on a substrate 10. Both ends of the resistive layer 22 in the X direction are electrically connected to the wiring 20b. The other configurations are the same as those in Example 1, and therefore description thereof will be omitted.

[0040] Resistance layer 22 is mainly composed of a metal having a resistivity higher than the resistivity of the main component metal of metal layers 17 and 13. For example, as shown in Table 1, when metal layers 17 and 13 are chromium layers and ruthenium layers, resistance layer 22 is a titanium layer or a titanium nitride layer.

[0041] [Modification 1 of Example 2] 3(b), in the first modification of the second embodiment, an insulating layer 24 is provided so as to cover the resistance layer 22. The insulating layer 24 is an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon nitride oxide film, or an aluminum oxide film. The other configurations are the same as those in the second embodiment, and therefore the description thereof will be omitted.

[0042] According to the second embodiment and its first modification, the resistor R1 is provided between two separated wirings 20a (first wiring and second wiring) and includes a resistive layer 22 (conductive layer) having both ends electrically connected to the separated wirings 20a. The resistor R2 is provided between two separated wirings 20b and includes a resistive layer 22 having both ends electrically connected to the separated wirings 20b. The resistive layer 22 has a resistive value larger than that of the metal layer 13 or 17. As a result, as shown in Table 1, the volume of the resistive layer 22 can be reduced, and the planar areas of the resistors R1 and R2 can be reduced. This allows the acoustic wave device to be miniaturized. In addition, the material used for the resistive layer 22 can be reduced. The resistive value of the resistive layer 22 is preferably 1.5 times or more, more preferably 2 times or more, of the resistive value of the metal layer 13 or 17. The thickness of the resistive layer 22 may be the same as or different from that of the metal layers 13 and 17. By making the resistive layer 22 thinner than the metal layers 13 and 17, the resistance values ​​of the resistors R1 and R2 can be increased.

[0043] In the wirings 20a and 20b, the metal layer 18 does not have to be provided on the metal layers 17 and 13. By providing the metal layer 18 on the metal layers 17 and 13 other than the resistive regions 30a and 30b, the resistance value of the wirings 20a and 20b can be reduced.

[0044] As in the first modification of the second embodiment, the insulating layer 24 is provided so as to cover the resistive layer 22, thereby preventing the resistive layer 22 from being electrically contacted with anything other than the wiring 20a or 20b, thereby making it possible to stabilize the resistance values ​​of the resistors R1 and R2. EXAMPLES

[0045] 4(a) to 4(c) are plan views of the resistive region and its vicinity of the acoustic wave device according to the third embodiment and its first and second modifications. As shown in FIG. 4(a), in the third embodiment, the width W3 of the metal layers 13 and 17 in the resistive regions 30a and 30b in the Y direction (the direction perpendicular to the extension direction of the wirings 20a and 20b) is smaller than the width W2 of the metal layers 13 and 17 in the Y direction in the wirings 20a and 20b. In the connection region 25 between the resistive regions 30a and 30b and the wirings 20a and 20b, the width of the metal layers 13 and 17 linearly decreases from the wirings 20a and 20b toward the resistive regions 30a and 30b. The angle θ1 between the contours of the metal layers 13 and 17 in the connection region 25 and the contours of the metal layers 13 and 17 in the resistive regions 30a and 30b is, for example, 20° to 70°. The other configurations are the same as those in the first embodiment, and description thereof will be omitted.

[0046] 4(b), in the first modification of the third embodiment, in the connection region 25, the widths of the metal layers 13 and 17 are curved and narrow from the wirings 20a and 20b toward the resistance regions 30a and 30b. In the connection region 25, the contours of the metal layers 13 and 17 are curved and concave inward. The other configurations are the same as those in the third embodiment, and therefore will not be described.

[0047] As shown in Fig. 4(c), in the second modification of the third embodiment, in the connection region 25, the metal layers 13 and 17 are meandering wiring 32. This allows the width W3 of the wiring 32 in the Y direction to be smaller than the width W2 of the wirings 20a and 20b, and the length of the wiring 32 to be larger than the width W1. This allows the resistance values ​​of the resistors R1 and R2 to be higher. The other configurations are the same as those of the third embodiment, and therefore a description thereof will be omitted.

[0048] 5(a) and 5(b) are cross-sectional views of the resistive region of the acoustic wave device according to the third and fourth modifications of the third embodiment. As shown in FIG. 5(a), in the third modification of the third embodiment, the thickness T3 of the metal layers 13 and 17 in the resistive regions 30a and 30b is smaller than the thickness T1 of the metal layers 13 and 17 in the wirings 20a and 20b. In the connection region 25, the thicknesses of the metal layers 13 and 17 decrease from the wirings 20a and 20b toward the resistive regions 30a and 30b. The angle θ2 between the upper surfaces of the metal layers 13 and 17 in the connection region 25 and the upper surfaces of the metal layers 13 and 17 in the resistive regions 30a and 30b is, for example, 60° to 80°. In the wirings 20a and 20b, a metal layer 18 is provided on the metal layers 13 and 17.

[0049] As shown in FIG. 5(b), in the fourth modification of the third embodiment, the wirings 20a and 20b are not provided with the metal layer 18. The other configurations are the same as those of the third modification of the third embodiment, and the description thereof will be omitted. In FIG. 5(a) and FIG. 5(b), the metal layers 17 and 13 are each illustrated as one layer, but the metal layers 17 and 13 may each be formed by stacking a plurality of layers. For example, in the metal layer 17, the lower layer 16a may be provided in the resistance region 30a, but the upper layer 16b may not be provided, and the wiring 20a may be provided with both the lower layer 16a and the upper layer 16b. In the metal layer 13, the lower layer 12a may be provided in the resistance region 30b, but the upper layer 12b may not be provided, and the wiring 20b may be provided with both the lower layer 12a and the upper layer 12b.

[0050] According to the third embodiment and its first and second modifications, the width W3 in the Y direction of the metal layers 17 and 13 in the resistors R1 and R2 is smaller than the width W2 in the Y direction of the metal layers 17 and 13 in the wirings 20a and 20b. According to the third and fourth modifications of the third embodiment, the thickness T3 of the metal layers 17 and 13 in the resistors R1 and R2 is smaller than the thickness T1 of the metal layers 17 and 13 in the wirings 20a and 20b. Thus, the cross-sectional area (W3×T3) of the metal layers 17 and 13 in the resistors R1 and R2 (conductive layers) perpendicular to the X direction is smaller than the cross-sectional area (W2×T1) of the metal layers 17 and 13 in the wirings 20a and 20b perpendicular to the X direction. This allows the resistors R1 and R2 to be formed by the metal layers 17 and 13. This allows for miniaturization and reduces the number of manufacturing steps. The width W3 may be smaller than the width W2 and the thickness T3 may be smaller than the thickness T1.

[0051] From the viewpoint of increasing the resistance value of the resistors R1 and R2, the width W3 is preferably 1 / 2 times or less of the width W2, more preferably 1 / 3 times or less, and even more preferably 1 / 5 times or less. The thickness T3 is preferably 3 / 4 times or less of the thickness T1, more preferably 1 / 2 times or less, and even more preferably 1 / 3 times or less. The cross-sectional area (W3×T3) is preferably 3 / 4 times or less of the cross-sectional area (W2×T1), more preferably 1 / 2 times or less, and even more preferably 1 / 3 times or less. From the viewpoint of suppressing disconnection of the resistors R1 and R2, the width W3 is, for example, 1 / 20 times or more of the width W2. The thickness T3 is 1 / 10 times or more of the thickness T1. The cross-sectional area (W3×T3) is preferably 1 / 200 times or more of the cross-sectional area (W2×T1).

[0052] According to the third embodiment and its first and second modifications, in the connection region 25, the widths of the metal layers 17 and 13 in the Y direction are gradually decreased from the wirings 20a and 20b to the resistors R1 and R2. According to the third and fourth modifications of the third embodiment, in the connection region 25, the thicknesses of the metal layers 17 and 13 are gradually decreased from the wirings 20a and 20b to the resistors R1 and R2. That is, in the connection region 25, the cross-sectional areas of the metal layers 17 and 13 are gradually decreased from the wirings 20a and 20b to the resistors R1 and R2. This can reduce the concentration of the electric field between the resistor regions 30a and 30b and the wirings 20a and 20b. Therefore, the power resistance when a large power is applied to the acoustic wave element 52 can be improved.

[0053] As in Example 3 and its Modifications 1 to 3, in the wirings 20a and 20b, a metal layer 18 may be provided on the metal layers 17 and 13. In Examples 1 to 3 and their Modifications, as in Modification 4 of Example 3, in the wirings 20a and 20b, a metal layer 18 may not be provided on the metal layers 17 and 13. In Example 2 and its Modification 1, the width in the Y direction of the resistive layer 22 in the resistive regions 30a and 30b may be made smaller than the width W2. The thickness of the resistive layer 22 may be made smaller than the thickness T1. EXAMPLES

[0054] In the fourth embodiment, the acoustic wave element 54 is a surface acoustic wave resonator. Fig. 6(a) is a plan view of the acoustic wave device in accordance with the fourth embodiment, and Fig. 6(b) is a cross-sectional view taken along line AA in Fig. 6(a).

[0055] 6(a) and 6(b), in acoustic wave element 54, metal layer 26 is provided on substrate 10. Acoustic wave element 54 has IDT 45 and reflector 46 formed by metal layer 26. Reflector 46 is provided on both sides of IDT 45 in the Y direction. IDT 45 includes a pair of opposing comb electrodes 44. Comb electrode 44 includes a plurality of electrode fingers 42 and bus bar 43 to which the plurality of electrode fingers 42 are connected. A region where electrode fingers 42 of a pair of comb electrodes 44 intersect when viewed from the Y direction is an intersection region.

[0056] The pair of comb-shaped electrodes 44 have electrode fingers 42 arranged alternately in at least a portion of the intersection region in the Y direction. An acoustic wave excited mainly by the electrode fingers 42 in the intersection region propagates mainly in the Y direction. The pitch of the electrode fingers 42 of one of the pair of comb-shaped electrodes 44 is approximately equal to the wavelength of the acoustic wave. The reflector 46 reflects the acoustic wave (surface acoustic wave) excited by the electrode fingers 42 of the IDT 45. This confines the acoustic wave within the intersection region of the IDT 45.

[0057] The wirings 20a, 20b and the pads 21a and 21b include a metal layer 26 and a metal layer 18 provided on the metal layer 26. The metal layer 18 is not provided in the resistor regions 30a and 30b.

[0058] The substrate 10 is a piezoelectric substrate, such as a lithium tantalate substrate, a lithium niobate substrate, or a quartz substrate. The lithium tantalate substrate and the lithium niobate substrate are, for example, rotated Y-cut X-propagation substrates. When the substrate 10 is a lithium tantalate substrate, the substrate 10 is, for example, a 32° to 50° rotated Y-cut X-propagation lithium tantalate substrate. The substrate 10 may be bonded onto a supporting substrate such as a sapphire substrate, a spinel substrate, an alumina substrate, a quartz substrate, or a quartz substrate.

[0059] The metal layer 26 is mainly composed of, for example, aluminum, copper or molybdenum. The metal layer 26 may have a metal layer mainly composed of titanium or chromium above or below the metal layer mainly composed of aluminum, copper or molybdenum. The material of the metal layer 18 is the same as that of the first embodiment. The thickness of the metal layer 26 is, for example, 0.05 to 0.2 times the wavelength of the elastic wave.

[0060] The other configurations are the same as those of the first embodiment, and therefore the description thereof will be omitted. In the first to third embodiments and their modifications, an acoustic wave element 54 that is a surface acoustic wave resonator as in the fourth embodiment may be used. EXAMPLES

[0061] A fifth embodiment is an example of the acoustic wave device 62 in Fig. 1. Fig. 7 is a plan view of the acoustic wave device in accordance with the fifth embodiment. Fig. 8 is a cross-sectional view taken along line AA in Fig. 7.

[0062] 7 and 8, in an acoustic wave device 62 according to a fifth embodiment, a capacitor C1 is connected between pads 21a and 21c, and a capacitor C2 is connected between pads 21b and 21c. A wiring 20c electrically connects the pad 21a to the capacitor C1 and the capacitor C1 to the pad 21c. A wiring 20d electrically connects the pad 21b to the capacitor C2 and the capacitor C2 to the pad 21c. The wirings 20c and 20d each include a metal layer 17 or 13 and a metal layer 18.

[0063] The capacitors C1 and C2 each include a lower electrode 37, a dielectric layer 36, and an upper electrode 38. The dielectric layer 36 is provided on the lower electrode 37, and the upper electrode 38 is provided on the dielectric layer 36. In the capacitor C2, the lower electrode 37 is formed of the lower layer 12a and the upper layer 12b, and is electrically connected to one of the wirings 20d. The upper electrode 38 is formed of a metal layer different from the lower layer 12a and the upper layer 12b, and is electrically connected to the other of the wirings 20d. The upper electrode 38 may be formed of the same material as the lower layer 12a and the upper layer 12b. The structure of the capacitor C1 is the same as that of the capacitor C2. The pads 21a, 21b, and 21c correspond to the nodes N2, N3, and N1 in FIG. 1, respectively. The other configurations are the same as those in the first embodiment, and will not be described.

[0064] As in the fifth embodiment, the capacitors C1 and C2 may be provided on the substrate 10. In the second to fourth embodiments and their modified examples, the capacitors C1 and C2 may be provided on the substrate 10. EXAMPLES

[0065] 9(a) and 9(b) are circuit diagrams of a filter according to a sixth embodiment and its first modification. As shown in FIG. 9(a), in filter 102 according to the sixth embodiment, resistor R1 is not provided, and node N2 is directly connected to acoustic wave element 52. The other configurations are the same as those in FIG. 1 according to the first embodiment, and description thereof will be omitted. As in the sixth embodiment, only one of resistors R1 and R2 may be provided. In the second to fifth embodiments and their modifications, only one of resistors R1 and R2 may be provided.

[0066] 9(b), in filter 104 according to the first modification of the sixth embodiment, resistor R3 is connected in parallel to acoustic wave element 52 between nodes N2 and N3. The other configurations are the same as those in the first embodiment shown in FIG. 1 and will not be described. As in the first modification of the sixth embodiment, resistor R3 may be connected in parallel to acoustic wave element 52. In the second to fifth embodiments and their modifications, resistor R3 may be provided in parallel to acoustic wave element 52.

[0067] According to the first to sixth embodiments and their modifications, in the filter, the capacitor C1 (first capacitor) and the capacitor C2 (second capacitor) are connected in series between the input terminal Tin and the output terminal Tout. One end of the inductor L1 is connected to a node N1 between the capacitors C1 and C2, and the other end of the inductor L1 is connected to the ground. The acoustic wave element 52 or 54 is connected in parallel with the capacitors C1 and C2 between the input terminal Tin and the output terminal Tout. The resistors R1 to R3 are connected in parallel with the capacitors C1 and C2 between the input terminal Tin and the output terminal Tout, and are connected in series or parallel with the acoustic wave elements 52 and 54. This makes it possible to make the attenuation region steep. The filter may be a high-pass filter or a low-pass filter.

[0068] An acoustic wave device including acoustic wave element 52 or 54 and resistors R1 to R3 may be used in circuits other than those shown in Fig. 1, 9(a), and 9(b). Resistors R1 to R3 are formed using a metal layer that is integral with at least one layer of the electrode of acoustic wave element 52 or 54. This allows resistors R1 to R3 to be connected in series or parallel to acoustic wave element 52 or 54. EXAMPLES

[0069] The seventh embodiment is an example of a multiplexer in which the filters of the first to sixth embodiments and their modified examples are used. FIG. 10 is a circuit diagram of a triplexer according to the seventh embodiment. As shown in FIG. 10, a triplexer 72 includes filters 74, 76, and 78. The filters 74, 76, and 78 are connected between a common terminal Ant and terminals LB, MB, and HB, respectively. An antenna 75 is connected to the common terminal Ant. The filter 74 is, for example, a low-pass filter, which passes a high-frequency signal in a low band and suppresses signals of other frequencies. The filter 76 is, for example, a band-pass filter, which passes a high-frequency signal in a middle band, which is a frequency higher than the low band, and suppresses signals of other frequencies. The filter 78 is, for example, a high-pass filter, which passes a high-frequency signal in a high band, which is a frequency higher than the middle band, and suppresses signals of other frequencies. The filter 74, 76, or 78 can be the filter 100, 102, or 104 of the first to sixth embodiments and their modified examples. Although a triplexer has been described as an example of the multiplexer, the multiplexer may be a diplexer, a duplexer, or a quadplexer.

[0070] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0071] 10 Substrate 12, 37 Lower electrode 12a, 16a lower layer 12b, 16b upper layer 13, 17, 18, 26 metal layer 14 Piezoelectric layer 16, 38 upper electrode 20a, 20b, 20c, 20d Wiring 21a, 21b, 21c Pads 22 Resistance layer 24 Insulating layer 25 Connection Area 30a, 30b resistance area 42 Electrode finger 44 Comb-shaped electrode 45 IDT 46 Reflector 50 resonance area 52, 54 Acoustic wave element 72 Triplexer 74, 76, 78 Filters

Claims

1. A substrate; an acoustic wave element provided on the substrate and having an electrode; a first metal layer provided on the substrate, made of the same material as at least one layer of the electrode, and electrically connected to the electrode; a second metal layer provided on the first metal layer; a conductive layer provided on the substrate, the conductive layer including the first metal layer but not the second metal layer; 1. An acoustic wave device comprising:

2. The acoustic wave device according to claim 1 , further comprising a wiring electrically connecting the conductive layer and the acoustic wave element, the wiring including the first metal layer and the second metal layer.

3. The acoustic wave device of claim 2 , wherein the second metal layer has a resistivity lower than that of the first metal layer.

4. The acoustic wave device according to claim 2 , wherein the second metal layer has a thickness greater than a thickness of the first metal layer.

5. The acoustic wave device according to claim 2 , wherein a cross-sectional area of ​​the first metal layer in the conductive layer perpendicular to an extension direction of the wiring is smaller than a cross-sectional area of ​​the first metal layer in the wiring perpendicular to the extension direction.

6. A substrate; an acoustic wave element provided on the substrate and having an electrode; a first wiring provided on the substrate, the first wiring including a first metal layer made of the same material as at least one layer of the electrode and electrically connected to the electrode; a second wiring including the first metal layer and separated from the first wiring; a conductive layer provided on the substrate, between the first wiring and the second wiring, both ends of which are electrically connected to the first wiring and the second wiring, respectively, and having a resistivity higher than a resistivity of the first metal layer; 1. An acoustic wave device comprising:

7. The acoustic wave device according to claim 6 , wherein the first wiring and the second wiring comprise a second metal layer provided on the first metal layer and having a resistivity lower than a resistivity of the conductive layer.

8. A substrate; an acoustic wave element provided on the substrate and having an electrode; a wiring provided on the substrate, the wiring including a first metal layer made of the same material as at least one layer of the electrode, the first metal layer being electrically connected to the electrode; a conductive layer provided on the substrate, electrically connected to the electrode via the wiring, made of the same material as at least a portion of the first metal layer, and having a cross-sectional area perpendicular to the extension direction of the wiring smaller than a cross-sectional area of ​​the wiring perpendicular to the extension direction; 1. An acoustic wave device comprising:

9. The acoustic wave device according to claim 8 , wherein in a connection region between the conductive layer and the wiring, a cross-sectional area of ​​the first metal layer perpendicular to the extension direction gradually decreases from the wiring to the conductive layer.

10. the acoustic wave element includes a lower electrode provided on the substrate, a piezoelectric layer provided on the lower electrode, and an upper electrode provided on the piezoelectric layer; The acoustic wave device according to claim 1 , wherein the electrode is the lower electrode or the upper electrode.

11. A filter comprising an acoustic wave device according to any one of claims 1 to 3 and 6 to 9.

12. An input terminal; An output terminal; a first capacitor and a second capacitor connected in series between the input terminal and the output terminal; an inductor having one end connected to a node between the first capacitor and the second capacitor and the other end connected to ground; Equipped with the acoustic wave element is connected in parallel with the first capacitor and the second capacitor between the input terminal and the output terminal; The filter according to claim 11 , wherein the conductive layer is connected in parallel with the first capacitor and the second capacitor between the input terminal and the output terminal, and is connected in series or parallel to the acoustic wave element.

13. A multiplexer comprising a filter according to claim 11.

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