Elastic wave devices and electronic modules

Abstract

This mitigates the spurious emission problem in elastic wave devices. [Solution] The piezoelectric layer 12 has a modified layer 113 on the support substrate 11. The modified layer 113 is formed by doping the support substrate 11 with a modifying element over a range extending from the second surface 112 to a predetermined position between the second surface 112 and the first surface 111. When viewed from a direction perpendicular to the third surface 121, at least one of the plurality of resonators 20 is a first resonator 20a, where the formation region of the resonator 20 is located inside the formation region of the modified layer 113, and at least one of the plurality of resonators 20 is a second resonator 20b, where the formation region of the resonator 20 is located outside the formation region of the modified layer 113. The first resonator 20a has a spurious mode resonance frequency of 1.2 times or more the principal mode resonance frequency.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic devices, and particularly to elastic wave devices and electronic modules.

Background Art

[0002] Elastic wave devices are widely used in various communication devices, specifically as resonators, band-pass filters, etc. By using a composite piezoelectric substrate in which a support substrate and a piezoelectric layer are laminated, it is possible to improve the temperature characteristics, Q value, and electromechanical coupling coefficient in the elastic wave device. However, in such an elastic wave device, there is a problem that spurious signals are generated due to the reflection of higher-order waves from the surface of the support substrate, which affects the device performance. Therefore, suppressing spurious signals is an important issue in elastic wave devices using this type of composite piezoelectric substrate.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to alleviate the problem of spurious signals in elastic wave devices, and to provide an elastic wave device and an electronic module capable of reducing spurious signals and improving the Q value.

Means for Solving the Problems

[0004] In order to achieve the above object, according to a first aspect of the present invention, an elastic wave device is provided with a support substrate having a first surface and a second surface facing the first surface, and having a modified layer, a piezoelectric layer directly or indirectly supported on the second surface of the support substrate, and a plurality of resonators provided on a third surface of the piezoelectric layer opposite to the side facing the second surface, The modified layer is formed by doping the support substrate with a modifying element in the thickness direction of the support substrate, over a range extending from the second surface to a predetermined position between the second surface and the first surface. In a view from a direction perpendicular to the third surface, at least one of the plurality of resonators is a first resonator provided such that the resonator formation region is located inside the formation region of the modified layer, At least one of the plurality of resonators is a second resonator provided such that the resonator formation region is located outside the formation region of the modified layer. Each of the multiple resonators has a principal mode and a spurious mode, and the resonant frequency of the spurious mode is set higher than the resonant frequency of the principal mode. The first resonator is configured such that the resonant frequency of the spurious mode is 1.2 times or more the resonant frequency of the main mode.

[0005] One embodiment of this invention is to make the resonant frequency of the spurious mode of the first resonator higher than the resonant frequency of the spurious mode of the second resonator.

[0006] Furthermore, one embodiment of this invention is to make the sound velocity of the modified layer in the support substrate greater than the sound velocity of the portion of the support substrate other than the modified layer.

[0007] Furthermore, one embodiment of this invention is to use sapphire as the main material of the support substrate.

[0008] Furthermore, one embodiment of this invention is to set the thickness of the modified layer to 0.025λ to 0.5λ, where λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode of the first resonator.

[0009] Furthermore, one embodiment of this invention is to use one or more of the following as the modifying element: carbon, boron, phosphorus, and nitrogen.

[0010] Furthermore, the concentration of the modifying element in the modified layer is set to 1 × 10⁻⁶. 17 ions / cm 3 or 5 x 10 20 ions / cm 3 This constitutes one aspect of the present invention.

[0011] Furthermore, one embodiment of this invention is to further include a high-sound-velocity layer located between the piezoelectric layer and the second surface, wherein the sound velocity of the high-sound-velocity layer is greater than the sound velocity of the piezoelectric layer.

[0012] Furthermore, one embodiment of this invention is to make the thickness of the high-sound-velocity layer less than or equal to half the thickness of the modified layer.

[0013] Furthermore, one embodiment of this invention involves making the sum of the thicknesses of the modified layer, the high-sound-velocity layer, and the piezoelectric layer less than λ, where λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode of the first resonator.

[0014] Furthermore, one embodiment of this invention is to further include a low-sound-velocity layer located between the piezoelectric layer and the second surface, wherein the sound velocity of the low-sound-velocity layer is lower than the sound velocity of the piezoelectric layer.

[0015] Furthermore, one embodiment of this invention is to set the thickness of the low-sound-velocity layer to 0.5λ or more, where λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode of the first resonator.

[0016] Furthermore, in order to achieve the above objectives, in this invention, from a second perspective, the electronic module comprises a wiring board, a plurality of external connection terminals and a sealing part, and the elastic wave device. [Effects of the Invention]

[0017] According to each of the above aspects of the present invention, it has at least one or more of the following advantageous effects. First, by setting the resonance frequency of the spurious mode of the first resonator to 1.2 times or more of the main mode, a sufficient frequency interval can be ensured between the two, reducing the interference caused by the spurious mode to the main mode, and improving the purity and stability of the signal. As a result, even if the same device operates at multiple frequencies, mutual interference is less likely to occur. Next, by providing a modified layer on the surface layer of the support substrate and arranging the first resonator corresponding to the modified layer, the frequency band of the spurious mode in the first resonator can be adjusted, and the interference of the spurious wave can be suppressed. Furthermore, since the modified layer effectively confines the elastic wave propagating in the piezoelectric thin film and prevents leakage to the outside, the Q value of the elastic wave device can be improved.

Brief Description of Drawings

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional structure diagram of an elastic wave device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional structure diagram of an elastic wave device according to a third embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional structure diagram of an elastic wave device according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a schematic plan structure diagram of a resonator in an elastic wave device according to an embodiment of the present invention. [Figure 5] FIG. 5 is an admittance characteristic diagram of resonators of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing the transmission-side insertion loss of a band-pass filter using Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. [Figure 7] FIG. 7 is a schematic diagram showing the reception-side insertion loss of a band-pass filter using Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. [Figure 8] FIG. 8 is a schematic diagram showing the maximum Q value of resonators of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. [Figure 9]Figure 9 is a schematic diagram showing the average Q values ​​of the resonators of Example 1 and Comparative Examples 1 and 2 of the present invention. [Figure 10] Figure 10 is a schematic cross-sectional view of the elastic wave device according to the fourth embodiment of the present invention. [Figure 11] Figure 11 is a schematic cross-sectional view of the elastic wave device according to the fifth embodiment of the present invention. [Figure 12] Figure 12 is a schematic cross-sectional view of the elastic wave device according to the sixth embodiment of the present invention. [Figure 13] Figure 13 is a schematic cross-sectional view of an electronic module according to the seventh embodiment of the present invention. [Modes for carrying out the invention]

[0019] To gain a clearer understanding of the above-mentioned objectives, features, and effects of the present invention, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. To enable those skilled in the art to better understand the technical concept of the present invention, the technical configuration will be described clearly and completely below with reference to drawings relating to embodiments of the present invention. However, the embodiments described are only a selection of embodiments of the present invention and do not encompass all embodiments. Other embodiments that those skilled in the art may conceive without creative effort based on the disclosure of the present invention should also be included within the scope of protection of the present invention. It should be noted that terms such as "first," "second," etc., used in this specification, the claims, and the drawings are for distinguishing similar subjects and do not indicate a specific order or priority. Such terms can be used interchangeably, and it should be understood that the embodiments of the present invention are not limited to the order shown or described. Furthermore, terms such as "include" and "possess" and their variations are intended to imply non-exclusive inclusion. That is, even when specific processes or components are listed, this does not exclude the inclusion of other processes or components that are not explicitly mentioned or are known in the relevant art. Furthermore, the distinctions between the multiple embodiments in the present invention are made for the sake of explanatory convenience and do not imply any particular limitation. The features described in each embodiment can be combined or referenced to each other as appropriate, as long as they do not contradict each other.

[0020] <First Embodiment> As shown in Figure 1, an elastic wave device 100 according to one embodiment of the present invention comprises a support substrate 11, a piezoelectric layer 12, and a resonator 20. The support substrate 11 includes a modified layer 113 embedded therein. The support substrate 11 has a first surface 111 and a second surface 112 facing each other, and the modified layer 113 is provided in the vicinity of the second surface 112. The modified layer 113 includes the main material of the support substrate and further includes doped modifying elements therein. The piezoelectric layer 12 is provided above the second surface 112.

[0021] The resonator 20 is located on the side of the piezoelectric layer 12 that is away from the support substrate 11. Here, the resonator 20 has a main mode and a spurious mode, and the resonant frequency of the spurious mode is higher than the resonant frequency of the main mode. The resonant frequency of the spurious mode is 1.2 times or more the resonant frequency of the main mode, which ensures a sufficient frequency gap between the two. As a result, interference between the spurious mode and the main mode is reduced, improving the purity and stability of the signal, and mutual interference is less likely to occur even when the same device operates at multiple frequencies.

[0022] Specifically, the main material of the support substrate 11 is a polycrystalline material, and more specifically, it may be one of the following: polycrystalline spinel, polycrystalline sapphire, polycrystalline aluminum nitride, polycrystalline magnesium oxide, polycrystalline quartz, or polycrystalline silicon carbide. The modified layer 113 is formed, for example, by doping the support substrate with a modifying element. The modifying element may be one or more of the following: nitrogen, boron, phosphorus, and carbon. The region of the support substrate 11 doped with the modifying element forms the modified layer 113, and the region not doped with the modifying element forms the unmodified layer 114 as the part other than the modified layer 113.

[0023] The following explanation uses the example of a support substrate 11 whose main material is sapphire (Al2O3) and whose modifying element is nitrogen. The modified layer 113 contains Al, O, and N, and can be understood as a nitrogen-doped Al2O3 layer. On the other hand, the unmodified layer 114 is an Al2O3 layer. The modified layer 113 is provided near the second surface 112 and is formed, for example, by ion implanting the modifying element into the support substrate from the second surface 112 side using a dopant source containing the modifying element. In this case, the modified layer 113 is formed in a thickness region extending from the second surface 112 towards the first surface 111 within the support substrate. The thickness of the modified layer 113 is shown as D1 in Figure 1. In other words, the modified layer 113 is formed by doping the support substrate 11 with a modifying element in the thickness direction of the support substrate 11, in a range extending from the second surface 112 to a predetermined position between the second surface 112 and the first surface 111. The modified layer 113 may be formed to be present in a portion of the support substrate 10. In Figure 1, the modified layer 113 is present throughout the entire support substrate 10, but in Figure 3, the modified layer 113 is present in a portion of the support substrate, i.e., the right-hand region.

[0024] The piezoelectric layer 12 is typically lithium tantalate or lithium niobate. The piezoelectric layer 12 may be directly bonded to the second surface 112 of the support substrate 11, or an appropriate dielectric layer, such as the high-sonic-velocity layer 13 shown in Figure 2 or the low-sonic-velocity layer 14 shown in Figure 10, may be provided between the piezoelectric layer 12 and the support substrate 11. The support substrate 11 and the piezoelectric layer 12, including the high-sonic-velocity layer and low-sonic-velocity layer, if present, together constitute a composite piezoelectric substrate 10. Of the piezoelectric layer 12, the surface not facing the support substrate 11 is the third surface 121. In other words, the piezoelectric layer 12 is directly or indirectly supported on the second surface 112 of the support substrate 11.

[0025] The resonators 20 are provided on the third surface 121, and there may be multiple resonators 20. Multiple resonators 20 can constitute a band-pass filter depending on their arrangement. Figure 4 shows an example of a resonator 20. The resonator 20 has an IDT electrode 20c (IDT, interdigital transducer) and a reflector 20d formed on either side of the IDT electrode 20c. The IDT electrode 20c is composed of electrode pairs, each electrode pair including a plurality of electrode fingers 20e and a busbar 20f connecting one end of these electrode fingers 20e. The reflector 20d includes a plurality of electrode fingers 20e and a busbar 20f connected to the opposing ends of these electrode fingers 20e.

[0026] Hereinafter, a resonator 20 provided such that its formation region is located inside the formation region of the modified layer 113 when viewed from a direction perpendicular to the third surface 121 will be referred to as the first resonator 20a.

[0027] In Figure 5, the characteristics corresponding to Example 1 show the admittance characteristics of the first resonator 20a. Specifically, the main material of the support substrate is sapphire, and the modifying element is nitrogen. Here, the dominant mode is the sound wave mode used during resonator operation, and in this embodiment, the dominant mode of the resonator 20 is the SH-SAW (Shear Horizontal Surface Acoustic Wave) mode. In this embodiment, the spurious mode refers to the high-frequency spurious signals that appear on the high-frequency side of the dominant mode. Referring to Figure 5, the resonant frequency Fr1 of the main mode of the first resonator 20a in Example 1 is 895 MHz, and the anti-resonant frequency Fa1 is 929 MHz. Furthermore, the resonant frequency Fr2 of the spurious mode of the first resonator 20a in Example 1 (the frequency at which the admittance value is maximum in the spurious mode) is approximately 1160 MHz. Therefore, in Example 1, the ratio of the resonant frequency Fr2 of the spurious mode to the resonant frequency Fr1 of the main mode of the first resonator 20a is approximately 1.3 times. Of course, the embodiments of the present invention are not limited to this. For example, the ratio of the resonant frequency of the spurious mode to the resonant frequency of the main mode of the first resonator 20a may be 1.25 times, 1.29 times, 1.4 times, or 1.5 times. In a preferred embodiment, Fr2 is 1.25 times or more than Fr1, and in a more preferred embodiment, Fr2 is 1.3 times or more than Fr1.

[0028] In the elastic wave device 100 according to this embodiment, by providing a modified layer 113 and arranging the first resonator 20a in correspondence with the modified layer 113, the following effects can be obtained. The resonant frequency of the spurious mode of the first resonator 20a can be changed, and the spurious mode can be moved outside the passband of the band-pass filter composed of multiple resonators 20. This reduces interference caused by spurious waves. Furthermore, the modified layer 113 can increase the sound velocity on the surface of the support substrate, effectively confining elastic waves propagating within the piezoelectric thin film and preventing leakage to the outside. As a result, the Q-factor of the elastic wave device can be improved.

[0029] The characteristics of the resonators according to this embodiment will be described below with reference to Figures 5 to 7. Figure 5 shows the admittance characteristics of the resonators of Example 1, Comparative Example 1, and Comparative Example 2. Figure 6 is a schematic diagram showing the transmitting insertion loss of the band-pass filters using Example 1, Comparative Example 1, and Comparative Example 2. Figure 7 is a schematic diagram showing the receiving insertion loss of the band-pass filters using Example 1, Comparative Example 1, and Comparative Example 2. The frequency bandwidth was set to Band 8. Comparative Example 1 uses a polycrystalline magnesium aluminate spinel substrate as the support substrate and corresponds to an elastic wave device without a modified layer, while Comparative Example 2 uses a polycrystalline sapphire substrate as the support substrate and corresponds to an elastic wave device without a modified layer. The resonant and anti-resonant frequencies of the main mode in Example 1 are approximately the same as those of the main mode in Comparative Examples 1 and 2. However, the resonant frequency of the spurious mode in Example 1 is higher than that of Comparative Examples 1 and 2. For example, as shown in Figure 5, the resonant frequency of the spurious mode in Example 1 is shifted by approximately 50 MHz towards the higher frequency side compared to Comparative Example 2. Furthermore, as shown in Figures 6 and 7, the insertion loss in Example 1 is reduced compared to Comparative Examples 1 and 2, both on the transmitting and receiving sides. Therefore, the elastic wave device 100 according to the embodiment of the present invention provides the effect of reducing insertion loss. Furthermore, comparing the Q values ​​in Comparative Example 1, Comparative Example 2, and Example 1, the values ​​for Example 1 are higher than those for Comparative Example 1 and Comparative Example 2 in both the maximum Q value shown in Figure 8 and the average Q value shown in Figure 9. Therefore, according to the elastic wave device 100 according to the embodiment of the present invention, the effect of improving the Q value can also be obtained.

[0030] The frequency difference between the resonant frequency of the spurious mode of the first resonator 20a and the anti-resonant frequency of the principal mode is 200 MHz or more, and may be, for example, 250 MHz or 300 MHz.

[0031] <Second Embodiment> As shown in Figure 3, the resonator 20 may further include a second resonator 20b. The second resonator 20b is located outside the region where the modified layer 113 is formed. That is, the modified layer 113 is present below the first resonator 20a, but not below the second resonator 20b. That is, in the embodiment shown in Figure 3, when viewed from a direction perpendicular to the third surface 121, at least one of the plurality of resonators 20 is a first resonator 20a, provided such that the formation region of the resonator 20 is located inside the formation region of the modified layer 113. At the same time, at least one of the plurality of resonators 20 is a second resonator 20b, provided such that the formation region of the resonator 20 is located outside the formation region of the modified layer 113. The resonant frequency of the spurious mode of the first resonator 20a is higher than the resonant frequency of the spurious mode of the second resonator 20b. The admittance characteristics of the second resonator 20b can be understood in the same way as the admittance characteristics of Comparative Example 2 shown in Figure 5. The difference between the resonant frequency of the spurious mode of the first resonator 20a and the resonant frequency of the spurious mode of the second resonator 20b is, for example, 50 MHz or more, and may specifically be 50 MHz, 60 MHz, or 100 MHz.

[0032] In some embodiments, the first resonator 20a is a transmitter-side resonator, which allows for better control of the transmitter-side filter. On the other hand, the second resonator 20b is a receiver-side resonator, which can be adapted to the requirements of different types of resonators.

[0033] In some embodiments, the thickness D1 of the modified layer 113 is 0.025λ to 0.5λ, and specifically may be 0.025λ, 0.05λ, 0.1λ, 0.2λ, 0.3λ, or 0.5λ. Here, λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode of the first resonator 20a.

[0034] In some embodiments, the concentration of the reforming element in the reforming layer 113 is 1 × 10⁻⁶ 17 ions / cm 3 or 5 x 10 20 ions / cm 3 By setting the range within this range, appropriate material properties and sound velocity can be imparted to the modified layer 113.

[0035] <Third Embodiment> As shown in Figure 2, the elastic wave device 100 may further include a high-sound-velocity layer 13. The high-sound-velocity layer 13 is located between the piezoelectric layer 12 and the second surface 112, and its sound velocity is greater than that of the piezoelectric layer 12. The high-sound-velocity layer 13 is, for example, a Si material layer, and may also be a thin film amorphous silicon layer. This can increase the bonding strength between the piezoelectric layer 12 and the support substrate 11, and can confine elastic waves to the piezoelectric layer 12 side, thereby improving the Q value.

[0036] The thickness of the high-speed layer 13 is preferably half or less of the thickness of the modified layer 113. This prevents the insertion loss from increasing due to an excessive thickness of the high-speed layer 13, which would adversely affect the performance of the elastic wave device. For example, the thickness of the high-speed layer 13 may be 0.3 times, 0.2 times, or 0.1 times the thickness of the modified layer 113.

[0037] The sum of the thicknesses of the modified layer 113, the high-sound-velocity layer 13, and the piezoelectric layer 12 is less than λ. Here, λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode of the first resonator 20a. Most of the energy of the surface elastic wave is concentrated in the thin layer near the surface, and the displacement of the main mode in the elastic wave device is mainly concentrated in the depth region of less than λ near the surface. Therefore, by using the above thickness configuration, most of the elastic wave energy can be concentrated within the effective operating region, and energy attenuation and loss can be reduced.

[0038] In this embodiment as well, as shown in the second embodiment, the modified layer 113 may be present below the first resonator 20a, but not below the second resonator 20b.

[0039] <Fourth Embodiment> Referring to Figure 10, the elastic wave device 100 further comprises a low-sound-velocity layer 14. The low-sound-velocity layer 14 is located between the piezoelectric layer 12 and the second surface 112, and its sound velocity is lower than that of the piezoelectric layer 12. By providing the low-sound-velocity layer 14, the sound velocity of the elastic wave can be reduced, and the energy of the elastic wave can be concentrated in the medium with a lower sound velocity (i.e., the low-sound-velocity layer 14). This reduces losses and improves the Q factor.

[0040] The material of the low-sonic wave layer 14 may be silicon dioxide, silicon oxynitride, tantalum oxide, or a material mainly composed of these materials. In some embodiments, silicon dioxide can be used as the intermediate layer, and lithium tantalate can be used as the material for the piezoelectric layer 12. Since lithium tantalate has a negative temperature characteristic elastic constant, while silicon dioxide has a positive temperature characteristic, combining these can reduce the absolute value of the TCF (temperature coefficient) of the elastic wave device.

[0041] The thickness of the low-sound-velocity layer 14 is 0.5λ or more. Here, λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode of the first resonator 20a. In some embodiments, the high-sound-velocity layer 13 and the low-sound-velocity layer 14 may be stacked in this order between the support substrate 11 and the piezoelectric layer 12.

[0042] In this embodiment as well, as shown in the second embodiment, the modified layer 113 may be present below the first resonator 20a, but not below the second resonator 20b.

[0043] <Fifth Embodiment> The elastic wave device 100 according to this embodiment may employ a encapsulation structure using a CSP (Chip Scale Package) or a WLP (Wafer Level Package).

[0044] Figure 11 is an example of a schematic diagram of the structure of an elastic wave device 100 employing CSP encapsulation. The elastic wave device 100 comprises an element (including a composite piezoelectric substrate 10 and a resonator 20), a package substrate 30, a first encapsulation structure 41, and a first external terminal electrode 53. The package substrate 30 is positioned opposite the surface on which the element's electrodes are formed, i.e., the third surface 121 of the piezoelectric layer 12, and a gap 60 is formed between the package substrate 30 and the third surface 121. The first encapsulation structure 41 is provided on the element side of the package substrate 30 and covers the side of the element and the surface opposite to the package substrate 30, sealing the gap 60 and encapsulating the entire element. The element's electrodes include an electrode pad 22 electrically connected to an IDT electrode 20c, and the electrode pad 22 is electrically connected via a bump 51 to a first conductive portion 52 formed on a wiring pattern on the package substrate 30. The first conductive portion 52 is electrically connected to a first external terminal electrode 53 formed on the side of the package substrate 30 opposite to the element, enabling electrical connection between the elastic wave device 100 and external equipment via the first external terminal electrode 53.

[0045] The materials for the package substrate 30 and the first encapsulation structure 41 can refer to substrate materials and encapsulation materials commonly used in existing CSP encapsulation structures. The electrode pads 22, bumps 51, first conductive portion 52, and first external terminal electrodes 53 are all made of materials with excellent conductivity, and this embodiment is not limited to these examples.

[0046] <Sixth Embodiment> Figure 12 is an example of a schematic diagram of the structure of an elastic wave device 100 employing WLP encapsulation. The elastic wave device 100 comprises an element (including a composite piezoelectric substrate 10 and a resonator 20), a cover 70, a second encapsulation structure 42, and a second external terminal electrode 55. The cover 70 is positioned opposite the surface on which the electrodes of the element are formed (i.e., the third surface 121 of the piezoelectric layer 12), and a gap 60 is formed between the cover 70 and the third surface 121. The electrodes of the element include an electrode pad 22 electrically connected to an IDT electrode 20c. The region on the third surface 121 on which the IDT electrode 21 is formed is called the effective region. The second encapsulation structure 42 is provided between the cover 70 and the element and is positioned to surround the effective region. The second encapsulation structure 42 surrounds the electrode pad 22, thereby sealing the element. The second external terminal electrode 55, located on the side of the cover 70 opposite to the element, is connected to the electrode pad 22 via a second conductive portion 54 that penetrates the cover 70 and the second sealing structure 42, thereby electrically connecting the elastic wave device 100 to external equipment via the second external terminal electrode 55.

[0047] The materials for the lid 70 and the second sealing structure 42 can refer to lid and sealing materials commonly used in existing WLP sealing structures. The electrode pads 22, the second conductive portion 54, and the second external terminal electrode 55 are all made of materials with excellent conductivity, and this embodiment is not limited to these examples.

[0048] <Seventh Embodiment> As shown in Figure 13, the present invention further provides an electronic module 1000. The electronic module 1000 comprises a wiring board 700, a plurality of external connection terminals 701, integrated circuit components 600, an elastic wave device 100 (including a composite piezoelectric substrate 10), an inductor 400, and a sealing portion 500. The plurality of external connection terminals 701 are formed on one surface of the wiring board 700, and these plurality of external connection terminals 701 are mounted on the motherboard of a given mobile communication terminal. The integrated circuit components 600 (also referred to as ICs) are mounted inside the wiring board 700. The integrated circuit components 600 include switching circuits and noise amplifiers. The elastic wave device 100 is mounted on the main surface of the wiring board 700. The inductor 400 is used for impedance matching, and for example, the inductor 400 may be an IPD (Integrated Passive Device). The sealing portion 500 is provided to seal the plurality of electronic components, including the elastic wave device 100, on the wiring board 700.

[0049] The electronic module 1000 according to this embodiment includes an elastic wave device 100 and has the same effects as the elastic wave device 100. Therefore, a detailed explanation thereof will not be repeated here.

[0050] The embodiments described above are merely preferred examples of the present invention and do not limit the invention in any form. Although the present invention has been disclosed in the above preferred embodiments, this is not intended to limit the invention, and various modifications, improvements, or equivalent configurations are possible for those skilled in the art, as long as they do not depart from the technical scope of the invention. Accordingly, simple modifications, equivalent substitutions, or changes made to the above embodiments in accordance with the technical idea and scope of the invention are all included within the technical scope of the invention. [Explanation of symbols]

[0051] 1000 Electronic Modules 100 Elastic wave devices 10. Composite piezoelectric substrate 11 Support substrate 111 First surface 112 Second surface 113 Modified layer 114 Unmodified layer 12 Piezoelectric layer 121 Third surface 13 High-sonic layer 14 Low sound speed layer 20 resonator 20a First resonator 20b Second resonator 20c IDT electrode 20d reflector 20e electrode finger 20ft Bus Bar 22 electrode pads 30 Package substrates 41 First sealing structure 42 Second sealing structure 51 Bump 52 First conductive part 53 1st external terminal electrode 54 Second conductive part 55 2nd external terminal electrode 60 void 70 Lid 400 Inductors 500 Sealing section 600 Integrated Circuit Components 700 Wiring board 701 External connection terminal

Claims

1. A support substrate having a first surface and a second surface opposite to the first surface, and having a modified layer, A piezoelectric layer directly or indirectly supported on the second surface of the support substrate, An elastic wave device comprising a plurality of resonators provided on a third surface of the piezoelectric layer opposite to the side facing the second surface, The modified layer is formed by doping the support substrate with a modifying element in the thickness direction of the support substrate, over a range extending from the second surface to a predetermined position between the second surface and the first surface. In a view from a direction perpendicular to the third surface, at least one of the plurality of resonators is a first resonator provided such that the resonator formation region is located inside the formation region of the modified layer, At least one of the plurality of resonators is a second resonator provided such that the resonator formation region is located outside the formation region of the modified layer. Each of the multiple resonators has a principal mode and a spurious mode, and the resonant frequency of the spurious mode is set higher than the resonant frequency of the principal mode. An elastic wave device comprising the first resonator wherein the resonant frequency of the spurious mode is set to 1.2 times or more the resonant frequency of the main mode.

2. The elastic wave device according to claim 1, wherein the resonant frequency of the spurious mode of the first resonator is made higher than the resonant frequency of the spurious mode of the second resonator.

3. The elastic wave device according to claim 1, wherein the sound velocity of the modified layer in the support substrate is made greater than the sound velocity of the portion of the support substrate other than the modified layer.

4. The elastic wave device according to claim 1, wherein the main body material of the support substrate is made of sapphire.

5. The elastic wave device according to claim 1, wherein the thickness of the modified layer is 0.025λ to 0.5λ, where λ is the wavelength of an elastic wave determined by the electrode period of the IDT electrode of the first resonator.

6. The elastic wave device according to claim 1, wherein the reforming element is one or more of carbon, boron, phosphorus, and nitrogen.

7. The concentration of the modifying element in the modified layer is 1 × 10 17 ions / cm 3 or 5 x 10 20 ions / cm 3 The elastic wave device according to claim 1.

8. The elastic wave device according to claim 1, further comprising a high-sound-velocity layer located between the piezoelectric layer and the second surface, wherein the sound velocity of the high-sound-velocity layer is greater than the sound velocity of the piezoelectric layer.

9. The elastic wave device according to claim 8, wherein the thickness of the high-sound-velocity layer is half or less the thickness of the modified layer.

10. The elastic wave device according to claim 8, wherein the sum of the thicknesses of the modified layer, the high-sound velocity layer, and the piezoelectric layer is less than λ, where λ is the wavelength of an elastic wave determined by the electrode period of the IDT electrode of the first resonator.

11. The elastic wave device according to claim 1, further comprising a low-sound velocity layer located between the piezoelectric layer and the second surface, wherein the sound velocity of the low-sound velocity layer is lower than the sound velocity of the piezoelectric layer.

12. The elastic wave device according to claim 11, wherein the thickness of the low-sound velocity layer is 0.5λ or more, where λ is the wavelength of the elastic wave determined by the electrode period of the IDT electrode of the first resonator.

13. An electronic module comprising a wiring board, a plurality of external connection terminals and a sealing portion, and an elastic wave device according to any one of claims 1 to 12.

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