Elastic wave device and module using the same

Abstract

The present application relates to an elastic wave device and a module using the elastic wave device. The elastic wave device comprises a supporting substrate; a dielectric layer, the dielectric layer is formed on the supporting substrate; an insulating layer, the insulating layer is formed on the dielectric layer; a piezoelectric layer, the piezoelectric layer is formed on the insulating layer; a resonator, the resonator comprises an IDT electrode and is formed on the piezoelectric layer; wherein the dielectric layer comprises a first acoustic impedance region having a strip shape with a long side direction and a short side direction; and a second acoustic impedance region having a strip shape which is arranged alternately with the first acoustic impedance region and has an acoustic impedance different from that of the first acoustic impedance region; when the wavelength of the elastic wave determined by the electrode spacing of the IDT electrode is λ, the total thickness of the insulating layer and the piezoelectric layer is less than 1.0λ. By using the elastic wave device of the present application, the elastic wave device has good temperature characteristics and can effectively suppress noise.

Description

Technical Field

[0001] The present application relates to an elastic wave device and a module using the same, and more particularly to an elastic surface wave device using SH waves, such as a filter, a duplexer or a multiplexer. Background Art

[0002] In high-frequency communication systems of mobile communication terminals represented by smartphones, high-frequency filters and other devices are usually used to remove unnecessary signals in non-communication frequency bands.

[0003] An elastic wave device having a surface acoustic wave (SAW) element is generally used in high-frequency filters and the like. The SAW element is an IDT (Inter Digital Transducer) element in which a pair of comb-shaped electrodes are formed on a piezoelectric layer.

[0004] For example, a method for manufacturing a surface acoustic wave device is as follows: First, a piezoelectric layer that transmits an elastic wave is bonded to a supporting substrate having a smaller thermal expansion coefficient than the piezoelectric layer to form a multilayer film substrate. Then, a plurality of IDT electrodes are formed on the multilayer film substrate using photolithography technology, and then a surface acoustic wave device having a predetermined size is obtained by cutting. By using a multilayer film substrate, the supporting substrate can suppress the dimensional change of the piezoelectric layer when the temperature changes, thereby stabilizing the frequency characteristics of the elastic wave device.

[0005] For example, Patent Document 1 (Japanese Patent Publication No. 2009-278610) is known to improve the temperature characteristics of an elastic wave device by bonding a supporting substrate such as a sapphire substrate having a high Young's modulus and a low linear expansion coefficient to the piezoelectric layer to suppress expansion and contraction due to temperature changes.

[0006] As described in Patent Document 1, in order to improve the temperature characteristics of elastic wave devices, a support substrate such as a sapphire substrate having a high Young's modulus and a low linear expansion coefficient is bonded to the piezoelectric layer to suppress expansion and contraction due to temperature changes. However, a resonator using such a support substrate is prone to generating noise at high frequencies, resulting in poor filtering characteristics. Summary of the invention

[0007] The present application aims to solve the above problems and to provide an elastic wave device having good temperature characteristics and capable of effectively suppressing noise, and a module using the elastic wave device.

[0008] In a first aspect, the present application provides an elastic wave device having:

[0009] A supporting substrate;

[0010] a dielectric layer, wherein the dielectric layer is formed on the supporting substrate;

[0011] an insulating layer, the insulating layer being formed on the dielectric layer;

[0012] a piezoelectric layer, the piezoelectric layer being formed on the insulating layer;

[0013] a resonator, the resonator comprising an IDT electrode and formed on the piezoelectric layer;

[0014] The dielectric layer includes a first acoustic impedance region having a strip shape with a long side direction and a short side direction; and a second acoustic impedance region having a strip shape and arranged alternately with the first acoustic impedance region and having an acoustic impedance different from that of the first acoustic impedance region;

[0015] When the wavelength of the elastic wave determined by the electrode interval of the IDT electrodes is λ, the total thickness of the insulating layer and the piezoelectric layer is 1.0λ or less.

[0016] In some embodiments, when the wavelength of the elastic wave determined by the electrode spacing of the IDT electrodes is λ, the total thickness of the dielectric layer, the insulating layer, and the piezoelectric layer is less than 1.0λ.

[0017] In a second aspect, the present application provides a module, comprising the elastic wave device described in the first aspect.

[0018] According to the present application, an elastic wave device having good temperature characteristics and capable of effectively suppressing noise and a module using the elastic wave device can be provided.

[0019] The details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0021] Figure 1 It is a cross-sectional view of the elastic wave device involved in the first embodiment of the present application.

[0022] Figure 2 It is a cross-sectional view of a device chip of the elastic wave device according to the first embodiment of the present application.

[0023] Figure 3 It is a top view of a functional element of the elastic wave device according to the first embodiment of the present application.

[0024] Figure 44 is a diagram showing resonance characteristics of a resonator of an elastic wave device according to the first embodiment of the present application.

[0025] Figure 5 It is a diagram showing the resonance characteristics of the elastic wave device according to the first embodiment of the present application and the resonator according to the first comparative example.

[0026] Figure 6 4 is a diagram showing resonance characteristics of a resonator of an elastic wave device according to a second embodiment of the present application.

[0027] Figure 7 4 is a diagram showing resonance characteristics of an elastic wave device according to the second embodiment of the present application and a resonator according to a second comparative example.

[0028] Figure 8 This is a cross-sectional view of an elastic wave device according to the present application in which five second acoustic impedance regions 12B are arranged within the range of eight electrode fingers 51 b.

[0029] Fig. 9 It is a top view of a functional element of an elastic wave device according to a third embodiment of the present application.

[0030] Fig.10 It is a diagram for explaining a method of manufacturing an elastic wave device.

[0031] Fig.11 It is a longitudinal cross-sectional view of a module to which the present application is applied to the elastic wave device according to the first embodiment, the second embodiment, or the third embodiment.

[0032] In the figure: 1, elastic wave device; 3, wiring substrate; 5, device chip; 7, packaging unit; 10, insulating layer; 11, piezoelectric layer; 12, dielectric layer; 13, supporting substrate; 50, elastic wave element; 12A, first acoustic impedance region; 12B, second acoustic impedance region; 100, module; 111, inductor; 117, packaging unit; 130, wiring substrate. DETAILED DESCRIPTION

[0033] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the", "these" and the like in this application do not represent quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether directly or indirectly. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. Usually, the character " / " indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0035] The following is based on Figures 1 to 11 , typical implementations of the present application are described.

[0036] First embodiment

[0037] Figure 1 It is a cross-sectional view of the elastic wave device involved in the first embodiment of the present application.

[0038] like Figure 1 As shown, elastic wave device 1 includes wiring substrate 3 , external connection terminals 31 , device chip 5 , electrode pads 9 , bumps 15 , and packaging portion 17 .

[0039] For example, the wiring substrate 3 is a multilayer substrate made of resin. For example, the wiring substrate 3 is a low temperature co-fired ceramic (LTCC) multilayer substrate composed of a plurality of dielectric layers.

[0040] External connection terminals 31 are formed on the lower surface of wiring substrate 3 .

[0041] The electrode pad 9 is formed on the main surface of the wiring substrate 3. For example, the electrode pad 9 is made of copper or an alloy containing copper. For example, the thickness of the electrode pad 9 is 10 μm to 20 μm.

[0042] Bumps 15 are formed on the upper surfaces of the electrode pads 9. For example, the bumps 15 are gold bumps. For example, the height of the bumps 15 is 10 μm to 50 μm.

[0043] A gap 16 is formed between the wiring substrate 3 and the device chip 5 .

[0044] The device chip 5 is mounted on the wiring substrate 3 by flip-chip bonding via bumps 15. The device chip 5 is electrically connected to the plurality of electrode pads 9 via the plurality of bumps 15.

[0045] The device chip 5 is a substrate on which the elastic wave element 50 is formed. For example, a plurality of transmission filters and reception filters are mainly formed on the main surface of the device chip 5, and these filters include the elastic wave element 50 of a plurality of resonators.

[0046] The transmission filter is designed to allow an electric signal of a desired frequency band to pass through. For example, the transmission filter is a ladder-type filter composed of a plurality of series resonators and a plurality of parallel resonators.

[0047] The reception filter is designed to allow an electric signal of a desired frequency band to pass through. For example, the reception filter is a ladder type filter.

[0048] The packaging part 17 is formed on the covering part of the device chip 5. For example, the packaging part 17 is made of insulating materials such as synthetic resin. In some other embodiments, the packaging part 17 can also be made of metal.

[0049] If the encapsulation part 17 is formed of a synthetic resin, the constituent material of the synthetic resin includes epoxy resin, polyimide, etc. Preferably, the encapsulation part 17 is formed of epoxy resin, and the epoxy resin is molded using a low temperature curing process.

[0050] Figure 2 It is a cross-sectional view of a device chip of the elastic wave device according to the first embodiment of the present application.

[0051] like Figure 2 As shown, the device chip 5 includes an insulating layer 10, a piezoelectric layer 11, a dielectric layer 12 and a supporting substrate 13. The elastic wave element 50 is formed on the piezoelectric layer 11.

[0052] The insulating layer 10 is made of silicon dioxide, and when the elastic wave wavelength determined by the electrode spacing of the IDT electrodes is λ, the thickness of the insulating layer 10 is 0.1λ to 0.9λ. It should be noted that in some other embodiments, the insulating layer 10 may also be made of silicon nitride.

[0053] The piezoelectric layer 11 may be a substrate made of a piezoelectric single crystal material such as lithium tantalate, lithium niobate or quartz. It should be noted that in other embodiments, the constituent material of the piezoelectric layer 11 may also be piezoelectric ceramics.

[0054] When the wavelength of the elastic wave determined by the electrode spacing of the IDT electrodes is λ, the thickness of the piezoelectric layer 11 may be 0.1λ to 0.9λ, preferably 0.1λ to 0.3λ.

[0055] The total thickness of the insulating layer 10 and the piezoelectric layer 11 is 1.0λ or less.

[0056] A semiconductor layer may be further included between the insulating layer 10 and the piezoelectric layer 11. The constituent material of the semiconductor layer may be silicon. By using silicon with a thickness of 5 nm to 20 nm in the bonding between the insulating layer 10 and the piezoelectric layer 11, bonding can be performed without adding unnecessary noise, thereby improving the bonding effect between the insulating layer 10 and the piezoelectric layer 11.

[0057] The dielectric layer 12 includes a first acoustic impedance region 12A and a second acoustic impedance region 12B. The constituent material of the first acoustic impedance region 12A includes silicon nitride, silicate nitride, silicon, aluminum oxide, silicon dioxide, or silicon carbide. The constituent material of the second acoustic impedance region 12B includes aluminum oxide, aluminum nitride, silicon nitride, silicate nitride, silicon, or silicon carbide, and the material used in the first acoustic impedance region 12A is different from the material used in the second acoustic impedance region 12B.

[0058] When the wavelength of the elastic wave determined by the electrode spacing of the IDT electrode is λ, the thickness of the dielectric layer 12 can be 0.05λ to 0.45λ. The total thickness of the insulating layer 10, the piezoelectric layer 11 and the dielectric layer 12, for example, when the wavelength of the elastic wave determined by the electrode spacing of the IDT electrode is λ, can be no more than 1.0λ.

[0059] When the elastic wave wavelength determined by the electrode spacing of the IDT electrodes is λ, the total thickness of the insulating layer 10, the piezoelectric layer 11 and the dielectric layer 12 does not exceed 1.0λ, wherein the thickness of the dielectric layer 12 ranges from 0.05λ to 0.45λ.

[0060] like Figure 2 In the example shown, the first acoustic impedance region 12A and the second acoustic impedance region 12B are arranged in three periods with respect to the four electrode fingers 51b on the piezoelectric layer 11. That is, three second acoustic impedance regions 12B are arranged within the range of the four electrode fingers 51b. Further explained, the first acoustic impedance region 12A and the second acoustic impedance region 12B are arranged at a pitch different from the pitch of the electrode fingers 51b; the first acoustic impedance region 12A and the second acoustic impedance region 12B are alternately arranged with the same thickness.

[0061] The support substrate 13 can be made of, for example, sapphire, silicon, alumina, spinel, silicon nitride, aluminum nitride, silicon carbide, silicate nitride, diamond, crystal, glass, etc. The smaller the thermal expansion coefficient of the support substrate 13 and the higher the Young's modulus, the better the improvement effect on the temperature characteristics of the elastic wave device 1. A typical substrate that meets these conditions is a sapphire substrate. Due to its high hardness and good chemical stability, it is not easy to process the surface into a convexoconcave shape or a serrated shape, resulting in a decrease in the yield rate. Therefore, the support substrate 13 is preferably a flat rectangular parallelepiped.

[0062] The thickness of the support substrate 13 ranges from 50 μm to 200 μm.

[0063] Figure 3 FIG. 1 is a top view of a functional element of an elastic wave device according to the first embodiment of the present application. Figure 3 The elastic wave element 50 formed on the piezoelectric layer 11 will be described.

[0064] Figure 3 For the convenience of explanation, the piezoelectric layer 11 is shown in perspective, and the piezoelectric layer 11 is not shown in the figure. Figure 2 An elastic wave element including an IDT (Interdigital Transducer) electrode 51 and a pair of reflectors 52 is formed on the main surface of the piezoelectric layer 11. The IDT electrode 51 and the pair of reflectors 52 are used to excite elastic waves (mainly SH waves).

[0065] Specifically, the IDT electrode 51 and the pair of reflectors 52 are made of an alloy of aluminum and copper. It should be noted that in some other embodiments, the constituent materials of the IDT electrode 51 and the pair of reflectors 52 may also include appropriate metals such as aluminum, molybdenum, iridium, tungsten, cobalt, nickel, ruthenium, chromium, strontium, titanium, palladium, silver, or alloys of the above metals.

[0066] Specifically, the IDT electrode 51 and the pair of reflectors 52 may be formed by a plurality of metal films which are stacked to form a laminated metal film. The thickness of the IDT electrode 51 and the pair of reflectors 52 ranges from 150 nm to 450 nm.

[0067] The IDT electrode 51 includes a pair of comb-shaped electrodes 51 a. The pair of comb-shaped electrodes 51 a are arranged opposite to each other. The comb-shaped electrodes 51 a include a plurality of electrode fingers 51 b and a bus bar 51 c.

[0068] The plurality of electrode fingers 51 b are arranged along the longitudinal direction. The bus bar 51 c connects the plurality of electrode fingers 51 b.

[0069] One of the pair of reflectors 52 is adjacent to one side of the IDT electrode 51 , and the other is adjacent to the other side of the IDT electrode 51 .

[0070] The piezoelectric layer 11 and the supporting substrate 13 ( Figure 3 A dielectric layer 12 is formed between the two (not shown). Figure 3 As shown in FIG. 1 , the first acoustic impedance region 12A and the second acoustic impedance region 12B are formed into stripe-shaped regions arranged in the long-side direction and the short-side direction. Figure 3 As shown in FIG. 1 , the first acoustic impedance regions 12A and the second acoustic impedance regions 12B are alternately arranged in the short-side direction.

[0071] like Figure 3 As shown in FIG. 1 , the long side direction of the first acoustic impedance region 12A and the second acoustic impedance region 12B is the same as the long side direction of the electrode finger 51 b .

[0072] Figure 4 This is a diagram of the resonance characteristics of the resonator of the elastic wave device 1 involved in the first embodiment of the present application. The constituent material of the insulating layer 10 is silicon dioxide. The piezoelectric layer 11 is made of single crystal lithium tantalate. The sound velocity of the body wave propagating in the insulating layer 10 is less than the sound velocity of the body wave propagating in the piezoelectric layer 11. The total thickness of the insulating layer 10 and the piezoelectric layer 11 is set to 0.65λ, that is, when the thickness of the piezoelectric layer 11 is 0.2λ, 0.25λ, 0.3λ, 0.4λ and 0.6λ, the thickness of the insulating layer 10 is 0.45λ, 0.4λ, 0.35λ, 0.25λ and 0.05λ respectively, and calculations are performed. The calculation results of the resonance characteristics of the piezoelectric layer 11 at thicknesses of 0.2λ, 0.25λ, 0.3λ, 0.4λ and 0.6λ are shown as follows. Figure 4 shown.

[0073] The thickness of the IDT electrode 51 is set to 0.1λ and is made of aluminum. The thickness of the dielectric layer 12 is set to 0.25λ. In addition, the width of the short side direction of the first acoustic impedance region 12A and the second acoustic impedance region 12B is the same, that is, the duty cycle is 50%. The first acoustic impedance region 12A is made of silicon dioxide. The second acoustic impedance region 12B is made of aluminum oxide. The support substrate 13 is a sapphire substrate.

[0074] like Figure 4 As shown in FIG. 1 , the peaks and valleys that appear around 900 MHz to 1000 MHz are caused by the intrinsic resonant mode. The peaks and valleys that appear in the high-frequency part outside this frequency range, that is, around 1200 MHz to 1700 MHz, are caused by non-intrinsic resonant modes and are called noise. If strong noise exists, it will cause significant degradation of characteristics when resonators are combined to form a filter, etc. Therefore, the smaller the height of the noise peak and the depth of the valley, the better the electrical performance of the elastic wave device 1.

[0075] like Figure 4As shown, the resonator of the elastic wave device according to the first embodiment shows particularly few parasitic responses in the resonance characteristics 0.2λ when the thickness of the piezoelectric layer 11 is 0.2λ, the resonance characteristics 0.25λ when the thickness of the piezoelectric layer 11 is 0.25λ, the resonance characteristics 0.3λ when the thickness of the piezoelectric layer 11 is 0.3λ, the resonance characteristics 0.4λ when the thickness of the piezoelectric layer 11 is 0.4λ, and the resonance characteristics 0.6λ when the thickness of the piezoelectric layer 11 is 0.6λ. The resonance characteristics 0.2λ, the resonance characteristics 0.25λ, and the resonance characteristics 0.3λ when the thickness of the piezoelectric layer 11 is 0.2λ, 0.25λ, and 0.3λ. In addition, when the thickness of the insulating layer 10 is larger than the thickness of the piezoelectric layer 11, the parasitic responses are particularly few.

[0076] Figure 5 Graph showing the resonance characteristics of the elastic wave device 1 according to the first embodiment and the resonator according to the first comparative example. The insulating layer 10 is made of silicon dioxide. The piezoelectric layer 11 is made of lithium tantalate. Calculations were performed to make the total thickness of the insulating layer 10 and the piezoelectric layer 11 0.65λ, that is, when the thickness of the piezoelectric layer 11 is 0.2λ and 0.3λ, the thickness of the insulating layer 10 is set to 0.45λ and 0.35λ, respectively. Other conditions are the same as for Figure 4 Same description as .

[0077] In the first comparative example, the total thickness of the insulating layer 10 and the piezoelectric layer 11 is set to 0.9λ, that is, when the thickness of the piezoelectric layer 11 is 0.2λ and 0.3λ, the thickness of the insulating layer 10 is set to 0.7λ and 0.6λ, respectively, and calculations are performed. The first comparative example does not include the dielectric layer 12. That is, in the first comparative example, silicon dioxide is used in the first acoustic impedance region 12A and the second acoustic impedance region 12B, and other conditions are the same as those in the first embodiment.

[0078] like Figure 5 As shown, in the resonance characteristics of the resonator of the elastic wave device in the first embodiment when the thickness of the piezoelectric layer 11 is 0.2λ and 0.3λ, the total thickness of the insulating layer 10 and the piezoelectric layer 11 is significantly improved in spurious signals compared with the resonance characteristics of 0.2λNS when the thickness of the piezoelectric layer 11 is 0.2λ and the resonance characteristics of 0.3λNS when the thickness of the piezoelectric layer 11 is 0.3λ in the first comparative example.

[0079] According to the first embodiment described above, an elastic wave device having good temperature characteristics and significantly reduced noise can be provided.

[0080] Second embodiment

[0081] In this embodiment, the insulating layer 10 is made of silicon nitride. When the wavelength of the elastic wave determined by the electrode spacing of the IDT electrodes is λ, the total thickness of the insulating layer 10 and the piezoelectric layer 11 is preferably less than 0.7λ.

[0082] The other structures of this embodiment are the same as those of the first embodiment, and thus the description thereof is omitted.

[0083] Figure 6 1 is a graph showing the resonance characteristics of the resonator of the elastic wave device 1 according to the second embodiment. The piezoelectric layer 11 is made of single crystal lithium tantalate. The results of calculation are shown in FIG. 1 by setting the total thickness of the piezoelectric layer 11 and the insulating layer 10 whose constituent material is silicon nitride to 0.65λ, that is, when the thickness of the piezoelectric layer 11 is 0.2λ, 0.25λ, 0.3λ, 0.4λ and 0.6λ, the thickness of the insulating layer is set to 0.45λ, 0.4λ, 0.35λ, 0.25λ and 0.05λ respectively. Figure 4 The calculated results of the resonance characteristics of the piezoelectric layer 11 with thicknesses of 0.2λ, 0.25λ, 0.3λ, 0.4λ and 0.6λ are as follows: Figure 4 shown.

[0084] The thickness of the IDT electrode 51 is set to 0.1λ and is made of aluminum. The thickness of the dielectric layer 12 is set to 0.25λ. In addition, the width of the first acoustic impedance region 12A and the second acoustic impedance region 12B in the short side direction is the same, that is, the duty ratio is 50%. The first acoustic impedance region 12A is made of silicon dioxide. The second acoustic impedance region 12B is made of aluminum oxide. The support substrate 13 is a sapphire substrate.

[0085] like Figure 6 As shown in the figure, the peaks and valleys around 950MHz to 1050MHz are caused by the original resonant mode. In the high-frequency range, the peaks and valleys around 1200MHz to 1700MHz are caused by non-original resonant modes, which are called spurious signals. If there are strong spurious signals, it will cause significant degradation of characteristics when the resonator is combined into a filter, etc. Therefore, the smaller the peak height and valley depth of the spurious signal, the better the characteristics.

[0086] like Figure 6 As shown, the resonator of the elastic wave device according to the second embodiment shows particularly few parasitic responses in the resonance characteristics 0.2λ when the thickness of the piezoelectric layer 11 is 0.2λ, the resonance characteristics 0.25λ when the thickness of the piezoelectric layer 11 is 0.25λ, the resonance characteristics 0.3λ when the thickness of the piezoelectric layer 11 is 0.3λ, the resonance characteristics 0.4λ when the thickness of the piezoelectric layer 11 is 0.4λ, and the resonance characteristics 0.6λ when the thickness of the piezoelectric layer 11 is 0.6λ. The resonance characteristics 0.2λ, the resonance characteristics 0.25λ, and the resonance characteristics 0.3λ when the thickness of the piezoelectric layer 11 is 0.2λ, 0.25λ, and 0.3λ. In addition, when the thickness of the insulating layer 10 is larger than the thickness of the piezoelectric layer 11, the parasitic responses are particularly few.

[0087] Figure 71 is a schematic diagram of the resonance characteristics of the elastic wave device 1 according to the second embodiment and the resonator of the second comparative example. The resonator of the elastic wave device 1 in the second embodiment uses a lithium tantalate piezoelectric layer 11. The result of the calculation is shown in FIG. 1 by setting the total thickness of the insulating layer and the piezoelectric layer 11 to 0.65λ, that is, when the thickness of the piezoelectric layer 11 is 0.2λ and 0.3λ, the thickness of the insulating layer is set to 0.45λ and 0.35λ respectively. Figure 7 Other conditions and Figure 6 Same as described in .

[0088] In the second comparative example, the total thickness of the insulating layer and the piezoelectric layer 11 formed on the sapphire substrate is set to 0.9λ, that is, when the thickness of the piezoelectric layer 11 is 0.2λ and 0.3λ, the thickness of the insulating layer is set to 0.7λ and 0.6λ respectively. The results are shown in Figure 7 The second comparative example does not include the dielectric layer 12. That is, in the second comparative example, both the first acoustic impedance region 12A and the second acoustic impedance region 12B are made of silicon dioxide, and other conditions are the same as those of the second embodiment.

[0089] like Figure 7 As shown, the resonator of the elastic wave device in embodiment 1 has significantly improved spurious signals in the resonance characteristics when the thickness of the piezoelectric layer 11 is 0.2λ and 0.3λ, and the total thickness of the insulating layer and the piezoelectric layer 11, compared with the resonance characteristics of 0.2λNS when the thickness of the piezoelectric layer 11 is 0.2λ and the resonance characteristics of 0.3λNS when the thickness of the piezoelectric layer 11 is 0.3λ in the second comparison example.

[0090] According to the second embodiment described above, it is possible to provide an elastic wave device having good temperature characteristics and significantly reduced noise.

[0091] The first and second embodiments described above show a good noise suppression effect under the condition that the first acoustic impedance region 12A and the second acoustic impedance region 12B are arranged in three periods based on four electrode fingers, but the relationship between the number of periods of the first acoustic impedance region 12A and the second acoustic impedance region 12B and the number of electrode fingers is not limited to this. However, it is preferred that the number of electrode fingers is inconsistent with the number of periods of the first acoustic impedance region 12A and the second acoustic impedance region 12B. The reason is that when the number of electrode fingers is consistent with the above-mentioned number of periods, the noise suppression effect will be weakened. For example, Figure 8 As shown, within the range of 8 electrode fingers 51b, it is also feasible to set the second acoustic impedance region 12B to 5 periods. In other words, under the premise that the number of electrode fingers is inconsistent with the number of periods of the first acoustic impedance region 12A and the second acoustic impedance region 12B, the combination of the number of electrode fingers and the number of periods is not limited.

[0092] Third embodiment

[0093] Fig. 9 FIG. 5 is a top view of a functional element 50 of an elastic wave device 1 according to a third embodiment of the present application. Fig. 9 As shown, the long side direction of the first acoustic impedance region 12A and the second acoustic impedance region 12B is different from the long side direction of the electrode finger 51b. This arrangement can generate an acoustic impedance difference in the transverse mode wave, thereby reducing the transverse mode noise.

[0094] The other structures are the same as those of the first embodiment, and thus the description thereof is omitted.

[0095] According to the third embodiment described above, it is possible to provide an elastic wave device in which high-frequency noise and transverse mode noise are significantly reduced.

[0096] Next, a method for manufacturing the elastic wave device 1 according to the first and second embodiments will be described. Fig.10 These are diagrams for explaining methods of manufacturing the elastic wave device 1 according to the first and second embodiments.

[0097] like Fig.10 As shown in (a), a first acoustic impedance film is formed on a supporting substrate 13. Next, the first acoustic impedance film is patterned. The patterning process is selected according to the material of the first acoustic impedance film, such as a lift-off method or an etching method.

[0098] like Fig.10 As shown in (b), the second acoustic impedance material is filled in the region where the first acoustic impedance film is removed by patterning. The filling method of the second acoustic impedance material is selected according to the material filling process, such as blade coating, evaporation or sputtering.

[0099] like Fig.10 As shown in (c), the second acoustic impedance material is ground to such an extent that the first acoustic impedance film is exposed. A suitable grinding process can be selected according to the material, such as chemical grinding or mechanical grinding.

[0100] like Fig.10 As shown in (d), after the grinding process, an insulating layer 10 is formed. The insulating layer 10 can be formed by a suitable process according to the material, such as a plasma CVD method or a sputtering method. Then, the insulating layer 10 is bonded to the piezoelectric layer 11. Alternatively, the insulating layer 10 can be first formed on the piezoelectric layer 11 and then bonded to the dielectric layer 12. Finally, by forming an elastic wave element 50 that meets the required device characteristics on the piezoelectric layer 11 and undergoing a packaging process, the elastic wave device 1 involved in the first embodiment and the second embodiment is obtained.

[0101] Fig.111 is a longitudinal cross-sectional view of a module of the elastic wave device 1 according to the first, second or third embodiment of the present application. The same or similar structures in the first, second or third embodiment are denoted by the same reference numerals, and their description is omitted here.

[0102] like Fig.11 As shown, module 100 includes wiring substrate 130 , a plurality of external connection terminals 131 , integrated circuit module IC, elastic wave device 1 , inductor 111 , and packaging unit 117 .

[0103] A plurality of external connection terminals 31 are formed on the lower surface of the wiring substrate 130. The plurality of external connection terminals 131 are pre-mounted on a main board of a predetermined mobile communication terminal.

[0104] Specifically, the integrated circuit assembly IC is mounted inside the wiring substrate 130. The integrated circuit assembly IC includes a switch circuit and a low noise amplifier.

[0105] Acoustic wave device 1 is mounted on the main surface of wiring substrate 130 .

[0106] The inductor 111 is mounted on the main surface of the wiring substrate 130. The inductor 111 is used for impedance matching. For example, the inductor 111 is an integrated passive device (IPD).

[0107] The packaging unit 117 is used to package a plurality of electronic components including the elastic wave device 1 .

[0108] Module 100 as described above includes elastic wave device 1. Therefore, it is possible to provide an elastic wave device module having good temperature characteristics and significantly reduced noise.

[0109] The expressions and terms used in the present invention are for illustrative purposes only and should not be considered as limiting. The use of "include", "have", "have", "include" and their variations as used herein means including the following listed items, their equivalents and additional items.

[0110] The term "embodiment" in this application refers to a specific feature, structure or characteristic described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various locations in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is clearly or implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0111] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations, corrections and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. An elastic wave device, characterized in that: have: A supporting substrate; a dielectric layer, wherein the dielectric layer is formed on the supporting substrate; an insulating layer, the insulating layer being formed on the dielectric layer; a piezoelectric layer, the piezoelectric layer being formed on the insulating layer; a resonator, the resonator comprising an IDT electrode and formed on the piezoelectric layer; Wherein, the dielectric layer comprises a first acoustic impedance region having a strip shape with a long side direction and a short side direction; and strip-shaped second acoustic impedance regions that are arranged alternately with the first acoustic impedance regions and have an acoustic impedance different from that of the first acoustic impedance regions; When the wavelength of the elastic wave determined by the electrode interval of the IDT electrodes is λ, the total thickness of the insulating layer and the piezoelectric layer is 1.0λ or less.

2. The elastic wave device according to claim 1, characterized in that: When the wavelength of the elastic wave determined by the electrode interval of the IDT electrodes is λ, the total thickness of the dielectric layer, the insulating layer, and the piezoelectric layer is less than or equal to 1.0λ.

3. The elastic wave device according to claim 1, characterized in that: The thickness of the insulating layer is greater than the thickness of the piezoelectric layer.

4. The elastic wave device according to claim 1, characterized in that: The insulating layer is made of silicon dioxide or silicon nitride.

5. The elastic wave device according to claim 1, characterized in that: The insulating layer is made of silicon nitride. When the wavelength of an elastic wave determined by an electrode interval of the IDT electrodes is λ, the total thickness of the insulating layer and the piezoelectric layer is less than or equal to 0.7λ.

6. The elastic wave device according to claim 1, characterized in that: The insulating layer is made of silicon dioxide. When the wavelength of the elastic wave determined by the electrode interval of the IDT electrode is λ, the thickness of the insulating layer is 0.1λ to 0.9λ.

7. The elastic wave device according to claim 6, characterized in that: The acoustic velocity of the bulk wave propagating in the insulating layer is lower than the acoustic velocity of the bulk wave propagating in the piezoelectric layer.

8. The elastic wave device according to claim 1, characterized in that: The elastic wave device further includes a semiconductor layer formed between the insulating layer and the piezoelectric layer.

9. The elastic wave device according to claim 1, characterized in that: The long side directions of the first acoustic impedance region and the second acoustic impedance region are the same as the long side directions of the electrode fingers of the IDT electrode.

10. The elastic wave device according to claim 1, wherein: The first acoustic impedance region and the second acoustic impedance region are arranged at a pitch different from an electrode pitch of the IDT electrodes.

11. The elastic wave device according to claim 1, characterized in that: When the wavelength of the elastic wave determined by the electrode interval of the IDT electrodes is λ, the thickness of the piezoelectric layer is 0.1λ to 0.3λ.

12. The elastic wave device according to claim 1, wherein: When the wavelength of the elastic wave determined by the electrode interval of the IDT electrodes is λ, the thickness of the dielectric layer is 0.05λ to 0.45λ.

13. The elastic wave device according to claim 1, wherein: The first acoustic impedance region is made of silicon dioxide.

14. The elastic wave device according to claim 1, characterized in that: The second acoustic impedance region is made of aluminum oxide, aluminum nitride, silicon nitride, silicate nitride, silicon or silicon carbide.

15. A module comprising the elastic wave device according to claim 1.

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