Electronic devices

Abstract

An electronic device. An electronic device comprising: a supporting substrate; a piezoelectric layer provided on the supporting substrate; a functional element including an electrode provided on a surface of the piezoelectric layer; a metal frame provided on the supporting substrate so as to surround the piezoelectric layer and the functional element in a plan view; a metal cover provided on the frame so as to form a space between the cover and the supporting substrate and to seal the functional element in the space; and a columnar body provided between the supporting substrate and the cover in the space.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2019-175663, filed on September 26, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Some aspects of the invention relate to electronic devices. Background Art

[0004] There is known an electronic device in which a cover is provided to form a space between the cover and a functional element such as an acoustic wave element provided on a substrate, and the functional element is sealed into the space (for example, Japanese Patent Application Publication Nos. 2013-58911, 2014-90340, 2014-143640, 2016-201780, and International Publication Pamphlet No. 2009 / 090895). Summary of the invention

[0005] In a structure in which a metal cover is disposed above the space, when pressure is applied to the cover, the cover may bend. The deflection of the cover causes the cover to come into contact with a functional element or the like, which may cause degradation of characteristics.

[0006] An object of the present disclosure is to provide an electronic device capable of reducing deflection of a cover.

[0007] According to one aspect of the present invention, there is provided an electronic device comprising: a supporting substrate; a piezoelectric layer disposed on the supporting substrate; a functional element comprising an electrode disposed on the surface of the piezoelectric layer; a metal frame disposed on the supporting substrate in a manner surrounding the piezoelectric layer and the functional element in a plan view; a metal cover disposed on the frame in a manner forming a space between the cover and the supporting substrate and sealing the functional element in the space; and a columnar body disposed between the supporting substrate and the cover in the space.

[0008] In the above configuration, the piezoelectric layer may have a through hole penetrating the piezoelectric layer, and the columnar body may be provided between the support substrate and the cover in the through hole.

[0009] In the above configuration, the height of the columnar body may be greater than the distance from the upper surface of the support substrate to the upper surface of the electrode.

[0010] In the above configuration, the columnar body may be provided to be separated from the piezoelectric layer.

[0011] In the above configuration, one end surface of the columnar body may be in contact with the support substrate, and the other end surface of the columnar body may be in contact with the cover.

[0012] In the above configuration, the piezoelectric layer may have a recessed portion on the bottom surface of which the piezoelectric layer exists, and the columnar body may be provided in the recessed portion between the supporting substrate and the cover.

[0013] In the above configuration, the cover may be grounded, and the columnar body may be made of metal and have a width that becomes narrower from the cover toward the support substrate.

[0014] In the above configuration, the columnar body may be located at the center of gravity of the region inside the frame of the cover and provided between the support substrate and the cover.

[0015] In the above configuration, the supporting substrate can be one of a sapphire substrate, an aluminum oxide substrate, a spinel substrate, a quartz substrate, a crystal substrate and a silicon substrate, the piezoelectric layer can be one of a single crystal lithium tantalate layer and a single crystal lithium niobate layer, and the functional element can be an acoustic wave element, which includes interdigitated electrodes as electrodes arranged on the piezoelectric layer.

[0016] In the above configuration, the functional element may be a piezoelectric thin film resonator including a lower electrode and an upper electrode as electrodes sandwiching a piezoelectric layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A is a cross-sectional view of an acoustic wave device according to a first embodiment, and Figure 1B is a plan view of an acoustic wave device according to a first embodiment;

[0018] Figure 2 is a plan view of an acoustic wave element according to a first embodiment;

[0019] Figure 3A is the circuit diagram of the filter, and Figure 3B It is the circuit diagram of a duplexer;

[0020] FIG. 4A to FIG. 4D is a cross-sectional view (part 1) illustrating a method of manufacturing an acoustic wave device according to a first embodiment;

[0021] FIG. 5A to FIG. 5C is a cross-sectional view (part 2) illustrating a method of manufacturing an acoustic wave device according to a first embodiment;

[0022] Fig. 6A is a cross-sectional view of an acoustic wave device of a comparative example, and Figure 6B is a plan view of an acoustic wave device according to a comparative example;

[0023] Figure 7 is a cross-sectional view for explaining a problem occurring in an acoustic wave device according to a comparative example;

[0024] Fig. 8A is a stereogram of the model used to simulate A. Figure 8B is a plan view of the model used to simulate A, and Figure 8C is a cross-sectional view of the model used for simulation A.

[0025] Fig. 9A and Fig. 9B is a diagram illustrating the deflection of the cover in Simulation A;

[0026] Fig. 10A is a plan view of the model used to simulate B, and Fig. 10B is a cross-sectional view of the model used for simulation B;

[0027] Fig.11A and Fig. 11B is a diagram illustrating the deflection of the cover in Simulation B;

[0028] Fig.12 is a plan view of an acoustic wave device according to a first modification of the first embodiment;

[0029] Fig.13 is a plan view of the model used to simulate C;

[0030] Fig.14A and Fig. 14B is a diagram illustrating the deflection of the cover in Simulation C;

[0031] Fig.15 is a plan view of an acoustic wave device according to a second modification of the first embodiment;

[0032] Fig.16 is a plan view of the model used to simulate D;

[0033] Fig.17A and Fig. 17B is a diagram illustrating the deflection of the cover in Simulation D;

[0034] Fig.18 is a cross-sectional view of an acoustic wave device according to a second embodiment;

[0035] Fig.19 is a cross-sectional view of an acoustic wave device according to a third embodiment;

[0036] Fig. 20 is a cross-sectional view of an acoustic wave device according to a fourth embodiment;

[0037] Fig.21 is a cross-sectional view of an acoustic wave device according to a fifth embodiment;

[0038] FIG. 22A to FIG. 22K is a plan view illustrating an example of a columnar body shape;

[0039] FIG. 23A to FIG. 23G is a side view illustrating an example of a columnar body shape; and

[0040] Fig.24A and Fig. 24B is a plan view illustrating an example of arrangement of columns. DETAILED DESCRIPTION

[0041] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings by using an acoustic wave device as an example of an electronic device.

[0042] First embodiment

[0043] Figure 1A is a cross-sectional view of an acoustic wave device according to a first embodiment, and Figure 1B is a plan view of the acoustic wave device according to the first embodiment. Figure 1B The cover 24, the frame 20, the piezoelectric layer 13 and the columnar body 30 are mainly shown. In the acoustic wave device 100 of the first embodiment, the piezoelectric layer 13 is bonded to the upper surface 11 of the support substrate 10, as shown in FIG. Figure 1A and Figure 1B As shown. The supporting substrate 10 is, for example, a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate or a silicon substrate. The sapphire substrate is a substrate containing single crystal Al2O3 as a main component. The alumina substrate is a substrate containing polycrystalline Al2O3 as a main component. The spinel substrate is a substrate containing single crystal or polycrystalline MgAl2O4 as a main component. The quartz substrate is a substrate containing amorphous SiO2 as a main component. The crystal substrate is a substrate containing single crystal SiO2 as a main component. The piezoelectric layer 13 is, for example, a single crystal lithium tantalate layer or a single crystal lithium niobate layer. The linear expansion coefficient of the supporting substrate 10 is smaller than the linear expansion coefficient of the piezoelectric layer 13. This makes it possible to reduce the frequency temperature coefficient of the acoustic wave device 100. An insulating layer such as silicon oxide or aluminum nitride can be provided between the piezoelectric layer 13 and the supporting substrate 10. Therefore, the piezoelectric layer 13 is directly or indirectly bonded to the supporting substrate 10.

[0044] One or more acoustic wave elements 15 are provided on the upper surface 14 of the piezoelectric layer 13. The piezoelectric layer 13 is not provided in the peripheral area of ​​the support substrate 10. In a plan view, the frame 20 is provided on the support substrate 10 in a manner surrounding the piezoelectric layer 13 and the acoustic wave element 15. The frame 20 is provided on the support substrate 10 and is separated from the piezoelectric layer 13. The frame 20 includes an annular metal layer 21 and an annular bonding layer 22. The annular metal layer 21 is in contact with the upper surface 11 of the support substrate 10. The annular bonding layer 22 is provided on the annular metal layer 21.

[0045] The terminal 18 is provided on the lower surface 12 of the support substrate 10. The terminal 18 is a footpad for electrically connecting the acoustic wave element 15 to the outside. The through-hole wiring 16 is provided to pass through the support substrate 10. One end of the through-hole wiring 16 is connected to the terminal 18. The other end of the through-hole wiring 16 is connected to the wiring 17 extending from the upper surface 14 of the piezoelectric layer 13 to the upper surface 11 of the support substrate 10. Thus, the acoustic wave element 15 is electrically connected to the terminal 18 via the wiring 17 and the through-hole wiring 16. The through-hole wiring 16a is provided to pass through the support substrate 10. The through-hole wiring 16a electrically connects the terminal 18a and the frame 20.

[0046] The cover 24 is disposed on the frame 20 in such a manner that a space 27 is formed between the cover 24 and the support substrate 10. The cover 24 is bonded to the frame 20. The acoustic wave element 15 is sealed in the space 27 formed by the cover 24 and the frame 20. The cover 24 includes a bonding layer 25 and a main body 26. The bonding layer 25 is bonded to the annular bonding layer 22. The main body 26 is thicker than the bonding layer 25 and is made of a harder material than the bonding layer 25, so that the cover 24 is less likely to be crushed.

[0047] Wiring 17, through-hole wiring 16 and 16a, terminals 18 and 18a, and annular metal layer 21 are metal layers such as copper layer, aluminum layer, platinum layer, nickel layer, or gold layer. Annular bonding layer 22 is a metal layer of a brazing material such as gold-tin, silver-tin, tin, or tin-silver-copper. Bonding layer 25 is a metal layer bonded to annular bonding layer 22, and is, for example, a gold layer. Main body 26 is a metal layer with a small linear expansion coefficient, such as a Kovar layer. Since frame 20 and cover 24 are made of metal, shielding effect can be given to frame 20 and cover 24 by providing ground potential to through-hole wiring 16a. In addition, since frame 20 and cover 24 are made of metal, acoustic wave element 15 can be sealed in space 27 with good airtightness. Frame 20 and cover 24 are not electrically connected to acoustic wave element 15 on supporting substrate 10.

[0048] The piezoelectric layer 13 has a through hole 40 that penetrates the piezoelectric layer 13 from the upper surface 14 to the lower surface. Although the through hole 40 is set as an opening in a part of the piezoelectric layer 13 as an example, the through hole 40 can also be set to divide the piezoelectric layer 13 into multiple pieces. In the through hole 40, for example, the upper surface 11 of the support substrate 10 is exposed. The column 30 is arranged between the support substrate 10 and the cover 24 in the through hole 40. The column 30 is located in the space 27. The column 30 is arranged to be separated from the piezoelectric layer 13. The column 30 includes a metal layer 31 and a bonding layer 32. The metal layer 31 is in contact with the upper surface 11 of the support substrate 10. The bonding layer 32 is arranged on the metal layer 31. Thus, one end of the column 30 is in contact with the upper surface 11 of the support substrate 10, and the other end of the column 30 is bonded to the cover 24.

[0049] The metal layer 31 is a metal layer such as a copper layer, an aluminum layer, a platinum layer, a nickel layer, or a gold layer, and is made of, for example, the same material as the annular metal layer 21. The bonding layer 32 is a brazing metal layer such as gold-tin, silver-tin, tin, or tin-silver-copper, and is made of, for example, the same material as the annular bonding layer 22. The columnar body 30 is not limited to being made of metal, but may be made of an insulating material such as ceramic.

[0050] The frame 20 extends around the piezoelectric layer 13 in the shape of a substantially rectangular frame, and surrounds the piezoelectric layer 13 and the acoustic wave element 15. Therefore, the surface of the support substrate 10 on one side in the inner region 29 of the cover inside the frame 20 has a substantially rectangular shape. The term "substantially rectangular shape" also includes the case where the vertices of the rectangle are rounded to the extent of manufacturing error and / or each side of the rectangle is curved. The inner region 29 of the cover 24 is exposed to the space 27. The columnar body 30 is located at the center of gravity of the inner region 29 of the cover 24 and is arranged between the support substrate 10 and the cover 24.

[0051] The support substrate 10 is, for example, a sapphire substrate, and its thickness is, for example, 50 μm to 300 μm. The piezoelectric layer 13 is, for example, a lithium tantalate layer of 42° rotation Y-cut X-propagation, and its thickness is, for example, 0.5 μm to 30 μm, and is, for example, the wavelength of the sound wave or less. The height of the frame 20 is, for example, 10 μm to 30 μm. The annular metal layer 21 is, for example, a stack of a copper layer with a thickness of 5 μm to 20 μm and a nickel layer with a thickness of 2.5 μm stacked from the support substrate 10 side. The annular bonding layer 22 is, for example, a gold-tin layer with a thickness of 3.5 μm. The bonding layer 25 of the cover 24 is, for example, a gold layer with a thickness of 2 μm. The main body 26 of the cover 24 is, for example, a Kovar plate with a thickness of 30 μm to 100 μm. For example, the through-hole wirings 16 and 16a are, for example, made of copper with a diameter of 30 μm to 100 μm. The terminal 18 is a stack of, for example, a 2 μm-thick copper layer, a 5 μm-thick nickel layer, and a 0.3 μm-thick gold layer stacked from the support substrate 10 side.

[0052] The width of the frame 20 is, for example, 20 μm to 30 μm. The distance between the side surface of the frame 20 and the side surfaces of the support substrate 10 and the cover 24 is, for example, 5 μm to 10 μm. The size of the support substrate 10 is, for example, 1.2 mm×1.0 mm. The distance between the lower surface 12 of the support substrate 10 and the upper surface of the cover 24 is, for example, 0.15 mm.

[0053] The height of the columnar body 30 is substantially the same as the height of the frame body 20, and is, for example, 10 μm to 30 μm. The length and width of the columnar body 30 are 20 μm to 30 μm. Like the annular metal layer 21, the metal layer 31 is, for example, a stack of a copper layer with a thickness of 5 μm to 20 μm and a nickel layer with a thickness of 2.5 μm stacked from the support substrate 10 side. Like the annular bonding layer 22, the bonding layer 32 is, for example, a gold-tin layer with a thickness of 3.5 μm. The distance D between the columnar body 30 and the piezoelectric layer 13 is, for example, 1 μm to 10 μm.

[0054] Figure 2 is a plan view of the acoustic wave element according to the first embodiment. Figure 2 As shown, the acoustic wave element 15 is a surface acoustic wave resonator. An IDT (interdigital transducer) 50 and a reflector 51 are formed on the upper surface 14 of the piezoelectric layer 13. The IDT 50 has a pair of interdigital electrodes 52 facing each other. Each of the interdigital electrodes 52 has a plurality of electrode fingers 53 and a bus bar 54 connecting the plurality of electrode fingers 53. The reflector 51 is arranged on both sides of the IDT 50. The IDT 50 excites a surface acoustic wave on the piezoelectric layer 13. The pitch between the electrode fingers 53 in one of the interdigital electrodes 52 is approximately equal to the wavelength λ of the acoustic wave. That is, the wavelength λ of the acoustic wave is approximately equal to twice the pitch between the electrode fingers 53 in a pair of interdigital electrodes 52. The IDT 50 and the reflector 51 are made of, for example, a metal film (such as an aluminum film, a copper film, or a molybdenum film). A protective film or a temperature compensation film covering the IDT 50 and the reflector 51 may be arranged on the upper surface 14 of the piezoelectric layer 13.

[0055] The filter or duplexer may be formed with a plurality of acoustic wave elements 15 formed on the upper surface 14 of the piezoelectric layer 13 . Figure 3A is the circuit diagram of the filter, and Figure 3B This is the circuit diagram of a duplexer. Figure 3A As shown, one or more series resonators S1 to S4 are connected in series between the input terminal Tin and the output terminal Tout. One or more parallel resonators P1 to P3 are connected in parallel between the input terminal Tin and the output terminal Tout. Each of the series resonators S1 to S4 and the parallel resonators P1 to P3 is an acoustic wave element 15. The number of series resonators and the number of parallel resonators can be appropriately set. Although the ladder filter is described as an example of the filter, the filter may be a multi-mode filter.

[0056] like Figure 3BAs shown, the transmission filter 60 is connected between the common terminal Ant and the transmission terminal Tx. The receiving filter 61 is connected between the common terminal Ant and the receiving terminal Rx. The transmission filter 60 allows the signal in the transmission band among the high-frequency signals input from the transmission terminal Tx to pass through the common terminal Ant as a transmission signal, and suppresses other signals with other frequencies. The receiving filter 61 allows the signal in the reception band among the high-frequency signals input from the common terminal Ant to pass through the receiving terminal Rx as a reception signal, and suppresses other signals of other frequencies. Although the duplexer is described as an example of a multiplexer, a triplexer or a quadplexer may be used.

[0057] (Manufacturing method)

[0058] FIG. 4A to FIG. 5C is a cross-sectional view illustrating a method of manufacturing an acoustic wave device according to a first embodiment. Figure 4A As shown, the upper surface 11 of the support substrate 10 is irradiated with, for example, a laser beam to form a through hole, and a metal layer such as copper is formed in the through hole by, for example, an electroplating method. Then, the upper surface of the metal layer is flattened by, for example, using a CMP (chemical mechanical polishing) method, so that the upper surface 11 of the support substrate 10 is exposed. Thus, through-hole wirings 16 and 16a are formed in the support substrate 10.

[0059] like Figure 4B As shown, for example, by using a surface activation method, the piezoelectric substrate is bonded to the upper surface 11 of the support substrate 10 at room temperature. The support substrate 10 and the piezoelectric substrate can be directly bonded via an amorphous layer of several nm or the like, or indirectly bonded via an insulating layer. Then, the upper surface of the piezoelectric substrate is polished, for example, by a CMP method. Thus, a piezoelectric layer 13 directly or indirectly bonded to the upper surface 11 of the support substrate 10 is formed.

[0060] like Figure 4C As shown, a portion of the piezoelectric layer 13 is removed, for example, by using an etching method. Thus, the piezoelectric layer 13 in the peripheral region of the support substrate 10 is removed, and the through-hole wirings 16 and 16a are exposed. In addition, a through hole 40 is formed in the piezoelectric layer 13. In the through hole 40, for example, the upper surface 11 of the support substrate 10 is exposed.

[0061] like Figure 4D As shown, the acoustic wave element 15 is formed on the upper surface 14 of the piezoelectric layer 13. The wiring 17 extending from the upper surface 14 of the piezoelectric layer 13 to the through-hole wiring 16 and electrically connecting the acoustic wave element 15 and the through-hole wiring 16 is formed.

[0062] like Figure 5AAs shown, the annular metal layer 21 and the annular bonding layer 22 are formed on the upper surface 11 of the support substrate 10 in a manner surrounding the piezoelectric layer 13 and the acoustic wave element 15. Thus, the frame 20 is formed. While the annular metal layer 21 and the annular bonding layer 22 are formed, a metal layer 31 made of the same material as the annular metal layer 21 and a bonding layer 32 made of the same material as the annular bonding layer 22 are formed on the upper surface 11 of the support substrate 10 exposed through the through hole 40 of the piezoelectric layer 13. Thus, the columnar body 30 is formed in the through hole 40.

[0063] like Figure 5B As shown, the cover 24 is bonded to the annular bonding layer 22 of the frame 20. Thus, the acoustic wave element 15 is sealed in the space 27 by the cover 24 and the frame 20. The cover 24 is also bonded to the bonding layer 32 of the columnar body 30.

[0064] like Figure 5C As shown, the lower surface 12 of the support substrate 10 is polished by, for example, a CMP method. Thus, the through-hole wirings 16 and 16a are exposed from the lower surface 12 of the support substrate 10. Terminals 18 and 18a connected to the through-hole wirings 16 and 16a are formed on the lower surface 12 of the support substrate 10. With the above steps, the acoustic wave device 100 of the first embodiment is manufactured.

[0065] (Comparative Example)

[0066] Fig. 6A is a cross-sectional view of an acoustic wave device according to a comparative example, and Figure 6B is a plan view of an acoustic wave device according to a comparative example. Figure 6B The cover 24, the frame 20 and the piezoelectric layer 13 are mainly shown. Fig. 6A and Figure 6B As shown, in the acoustic wave device 1000 of the comparative example, the columnar body 30 is not provided between the support substrate 10 and the cover 24. The other configuration of the acoustic wave device 1000 is the same as that of the acoustic wave device 100 of the first embodiment, and the description thereof will be omitted.

[0067] Figure 7 27 is a cross-sectional view for explaining a problem that occurs in an acoustic wave device according to a comparative example. For example, when a plurality of electronic components including an acoustic wave device 1000 mounted on a wiring board are sealed with a molded resin, the wiring board is placed in a cavity of a resin-sealed device, and then the resin is poured into the cavity. When the resin is poured into the cavity, pressure is applied to the acoustic wave device 1000. In order to improve the airtightness of the space 27, the frame 20 and the cover 24 are preferably made of metal. However, when the cover 24 is made of metal, ductility becomes high. Therefore, when pressure is applied to the cover 24, the cover 24 may be deformed as shown in FIG. Figure 7 When the cover 24 is flexed, the cover 24 comes into contact with the acoustic wave element 15 and / or the wiring 17, and the characteristics may be deteriorated.

[0068] (simulation)

[0069] A description will be given of a simulation for calculating the deflection when pressure is applied to the cover. The simulation was performed using a simple model that only considers the frame 20 and the cover 24 . Fig. 8A is a stereogram of the model used to simulate A. Figure 8B is a plan view of the model used to simulate A, and Figure 8C is a cross-sectional view of the model used to simulate A. FIG. 8A to FIG. 8C As shown, the cover 24 is a rectangular shape with a length X of 1.284 mm, a width Y of 0.784 mm, and a height Z of 30 μm. The width D of the frame 20 is 23 μm and the height H is 20 μm. The cover 24 is made of Kovar alloy with a Young's modulus of 138 GPa and a Poisson's ratio of 0.317. The frame 20 is made of copper with a Young's modulus of 110 GPa and a Poisson's ratio of 0.343. Figure 8C As shown, the deflection of the cover 24 is simulated when the lower surface 28 of the frame 20 is fixed and a pressure F is applied to the upper surface of the cover 24. The pressure F is set to 6 MPa corresponding to the pressure when the molded resin is formed.

[0070] Fig. 9A and Fig. 9B 3 is a diagram illustrating the deflection of the cover in Simulation A. Fig. 9A 2 is a side view showing an example of the amount of deflection relative to a reference when the non-deflected portion of the cover 24 is used as a reference. Fig. 9B are contour plots (they also apply to the following simulation results). Regarding the deflection amount, the deflection toward the frame 20 is represented by a negative value. Fig. 9A and 9B As shown, the deflection increases as the center of gravity of the inner region 29 of the cover 24 is approached. The maximum deflection is -17.6 μm.

[0071] The simulation was also performed when the pressure F was set to 12 MPa and 18 MPa corresponding to the hydrostatic pressure test. Even in this case, it was confirmed that the cover 24 Fig. 9A and Fig. 9B The same shape was deflected. When the pressure F was 12 MPa, the maximum deflection amount was -35.2 μm, and when the pressure F was 18 MPa, the maximum deflection amount was -52.8 μm.

[0072] Fig. 10A is a plan view of the model used to simulate B, and Fig. 10B is a cross-sectional view of the model used to simulate B. Fig. 10A and Fig. 10BAs shown, in simulation B, the columnar body 30 is disposed at the center of gravity of the inner region 29 of the cover 24. The columnar body 30 is a rectangular shape having a length of 23 μm, a width of 23 μm, and a height of 20 μm. The columnar body 30 is made of copper having a Young's modulus of 110 GPa and a Poisson's ratio of 0.343. The other configurations of simulation B are the same as those of simulation A. Fig. 10B As shown, when the lower surface 28 of the frame body 20 and the lower surface 38 of the columnar body 30 are fixed and a pressure F of 6 MPa is applied to the upper surface of the cover 24, the deflection of the cover 24 is simulated.

[0073] Fig.11A and Fig. 11B is a diagram illustrating the deflection of the cover in Simulation B. Fig.11A and Fig. 11B When the columnar body 30 is provided, the maximum deflection is -6.4 μm.

[0074] The acoustic wave device 1000 of the comparative example does not have Fig. 6A and Figure 6B In this case, as shown in the column 30. Fig. 9A and 9B As shown in FIG. 1 , when the pressure F is applied to the cover 24, the deflection of the cover 24 becomes larger. Figure 7 As shown, the cover 24 is deflected and comes into contact with the acoustic wave element 15 and / or the wiring 17 , and the characteristics may be deteriorated.

[0075] On the other hand, according to the acoustic wave device 100 of the first embodiment, as Figure 1A and Figure 1B As shown, a columnar body 30 is provided between the support substrate 10 and the cover 24 in the space 27. In this case, as shown in FIG. Fig.11A and Fig. 11B As shown, even when the pressure F is applied to the cover 24, the deflection of the cover 24 can be reduced. Therefore, the cover 24 can be prevented from contacting the acoustic wave element 15 and the wiring 17, and the degradation of the characteristics can be suppressed. From the perspective of reducing the deflection of the cover 24, the length and width of the columnar body 30 are preferably 20 μm or more, more preferably 30 μm or more, and further more preferably 40 μm or more. Moreover, from the perspective of reducing the area of ​​the piezoelectric layer 13, the length and width of the columnar body 30 are preferably 100 μm or less, more preferably 80 μm or less, and further more preferably 60 μm or less.

[0076] The piezoelectric layer 13 preferably has a through hole 40 penetrating the piezoelectric layer 13, and the columnar body 30 is preferably provided between the support substrate 10 and the cover 24 in the through hole 40. Thus, even when pressure is applied to the cover 24 and the columnar body 30 is pushed, the load is suppressed from being applied to the piezoelectric layer 13. Therefore, the generation of cracks in the piezoelectric layer 13 can be suppressed.

[0077] The height of the columnar body 30 is preferably greater than the distance from the upper surface 11 of the support substrate 10 to the upper surface of the interdigital electrode 52 forming the acoustic wave element 15. Even when the cover 24 is flexed, the cover 24 is prevented from contacting the acoustic wave element 15, thereby suppressing characteristic degradation.

[0078] The piezoelectric layer 13 is a single crystal lithium tantalate layer or a single crystal lithium niobate layer. In this case, since the piezoelectric layer 13 has a cleavage property, the piezoelectric layer 13 is easily broken when a load is applied. In this case, the columnar body 30 is preferably arranged between the support substrate 10 and the cover 24 in the through hole 40 of the piezoelectric layer 13. In addition, in the case where the thickness of the piezoelectric layer 13 is equal to or less than the wavelength λ of the sound wave, the piezoelectric layer 13 is easily broken when a load is applied. Therefore, even in this case, the columnar body 30 is preferably arranged between the support substrate 10 and the cover 24 in the through hole 40 of the piezoelectric layer 13.

[0079] In order to suppress the load applied to the piezoelectric layer 13 when the columnar body 30 is pushed by the cover 24, it is preferred that the columnar body 30 is provided separately from the piezoelectric layer 13. From the perspective of suppressing the load applied to the piezoelectric layer 13 and suppressing the increase in the size of the acoustic wave device, the distance D between the columnar body 30 and the piezoelectric layer 13 is preferably greater than 2 μm and less than 10 μm, more preferably greater than 3 μm and less than 8 μm, and further preferably greater than 4 μm and less than 6 μm.

[0080] The columnar body 30 contacts one of the support substrate 10 and the cover 24 and does not contact the other, and a gap may be formed. However, in order to effectively reduce the deflection of the cover 24, it is preferred that one end surface of the columnar body 30 contacts the support substrate 10 and the other end surface contacts the cover 24.

[0081] The columnar body 30 is preferably provided at the center of gravity of the inner region 29 of the cover 24, and is provided between the support substrate 10 and the cover 24. Thus, even when pressure is applied to the cover 24, deflection of the cover 24 can be effectively reduced.

[0082] In order to reduce the height of the acoustic wave device 100, it is preferable that the thickness of the cover 24 is smaller than the thickness of the support substrate 10. In this case, the cover 24 is easily flexed when pressure is applied to the cover 24. Therefore, in this case, it is preferable to provide the columnar body 30.

[0083] Preferably, wiring 17 is not provided below columnar body 30. Thus, even when pressure is applied to cover 24 and columnar body 30 is pushed, propagation of stress to piezoelectric layer 13 via wiring 17 is suppressed, and generation of cracks in piezoelectric layer 13 can be suppressed.

[0084] (First Modification of First Embodiment)

[0085] Fig.12 is a plan view of an acoustic wave device according to a first modification example of the first embodiment. Fig.12 The cover 24, the frame 20, the piezoelectric layer 13, and the columns 30a and 30b are mainly shown. Fig.12 As shown, in the acoustic wave device 110 of the first modification of the first embodiment, when the inner region 29 of the cover 24 is viewed in a plan view, the columns 30a and 30b are located on a virtual line 70 along the length direction of the inner region 29, and the columns 30a and 30b are provided between the support substrate 10 and the cover 24. For example, the columns 30a and 30b are provided at positions symmetrical to each other with respect to the center of gravity 71 of the inner region 29 of the cover 24. For example, the distance A between the frame 20 and the column 30a, the distance B between the column 30a and 30b, and the distance C between the column 30b and the frame 20 are approximately the same size as each other. The other configurations of the acoustic wave device 110 are the same as those of the acoustic wave device 100 of the first embodiment, and thus descriptions thereof are omitted.

[0086] (simulation)

[0087] Fig.13 It is a plan view of a model for simulation C. In simulation C, when the inner region 29 of the cover 24 is observed in a plane, the columns 30a and 30b are located on a virtual line 70 along the length direction of the inner region 29. The columns 30a and 30b are arranged at positions symmetrical to each other relative to the center of gravity 71 of the inner region 29 of the cover 24. The distance X1 between the center of the frame 20 and the column 30a, the distance X2 between the center of the column 30a and the center of 30b, and the distance X3 between the center of the column 30b and the frame 20 all have the same size (i.e., 0.448 mm). As with simulation B, each column 30a and 30b is a rectangular shape with a length of 23 μm, a width of 23 μm, and a height of 20 μm, and is made of copper with a Young's modulus of 110 GPa and a Poisson's ratio of 0.343. The other configurations of simulation C are the same as those of simulation A. When the frame body 20 and the lower surfaces of the columns 30 a and 30 b are fixed and a pressure F of 6 MPa is applied to the upper surface of the cover 24 , the deflection of the cover 24 is simulated.

[0088] Fig.14A and Fig. 14Bis a diagram illustrating the deflection of the cover in Simulation C. When the columns 30a and 30b are as Fig.14A and 14B When arranged as shown, the maximum deflection is reduced to -2.5 μm.

[0089] As shown in the first variant of the first embodiment, the columns 30a and 30b can be located on the virtual line 70 along the length direction of the inner area 29, and can be arranged between the support substrate 10 and the cover 24. Thereby, the deflection of the cover 24 can be reduced. From the perspective of reducing the deflection of the cover 24, it is preferred that the columns 30a and 30b are arranged at positions symmetrical to each other relative to the center of gravity 71 of the inner area 29 of the cover 24. In addition, the columns 30a, 30b are preferably arranged so that the distance A between the frame 20 and the column 30a, the distance B between the column 30a and the column 30b, and the distance C between the column 30b and the frame 20 are approximately the same size as each other. The term "approximately the same" includes differences in the degree of manufacturing errors.

[0090] (Second Modification of First Embodiment)

[0091] Fig.15 is a plan view of an acoustic wave device according to a second modification of the first embodiment. Fig.15 As shown, in the acoustic wave device 120 of the second modification of the first embodiment, when the inner region 29 of the cover 24 is viewed in a plan view, the columns 30c and 30d are located on the diagonal line 72 of the inner region 29, and the columns 30c and 30d are provided between the support substrate 10 and the cover 24. For example, the columns 30c and 30d are provided at positions symmetrical to each other with respect to the center of gravity 71 of the inner region 29 of the cover 24. For example, the distance A between the corner of the inner region 29 and the column 30c, the distance B between the column 30c and the column 30d, and the distance C between the column 30d and the other corner of the inner region 29 are approximately the same size as each other. The other configurations of the acoustic wave device 120 are the same as those of the acoustic wave device 100 of the first embodiment, and thus descriptions thereof will be omitted.

[0092] (simulation)

[0093] Fig.16: is a plan view of a model for simulation D. In simulation D, when the inner region 29 of the cover 24 is viewed in plan view, the columns 30c and 30d are located on the diagonal 72 of the inner region 29. The columns 30c and 30d are arranged at positions symmetrical to each other with respect to the center of gravity 71 of the inner region 29 of the cover 24. The distance X1 between the corner of the inner region 29 of the cover 24 and the center of the column 30c, the distance X2 between the center of the column 30c and the center of the column 30d, and the distance X3 between the center of the column 30d and the other corner of the inner region 29 of the cover 24 all have the same size (i.e., 0.478 mm). As with simulation B, each column 30a and 30b is a rectangular shape with a length of 23 μm, a width of 23 μm, and a height of 20 μm, and is made of copper with a Young's modulus of 110 GPa and a Poisson's ratio of 0.343. The other configurations of simulation D are the same as those of simulation A. When the frame body 20 and the lower surfaces of the columnar bodies 30 c and 30 d were fixed and a pressure F of 6 MPa was applied to the upper surface of the cover 24 , the deflection of the cover 24 was simulated.

[0094] Fig.17A and Fig. 17B is a diagram illustrating the deflection of the cover in Simulation D. When the columns 30c and 30d are as Fig.17A and Fig. 17B When arranged as shown, the maximum deflection is reduced to -4.7 μm.

[0095] As shown in the second modification of the first embodiment, the columns 30c and 30d may be located on the diagonal line 72 of the inner region 29, and may be provided between the support substrate 10 and the cover 24. Therefore, the deflection of the cover 24 can be reduced. From the perspective of reducing the deflection of the cover 24, it is preferred that the columns 30c and 30d are provided at positions symmetrical to each other with respect to the center of gravity 71 of the inner region 29 of the cover 24. In addition, the columns 30c and 30d are preferably provided so that the distance A between the corner of the inner region 29 and the column 30c, the distance B between the column 30c and the column 30d, and the distance C between the column 30d and the other corner of the inner region 29 are approximately the same size as each other.

[0096] In the first modification example and the second modification example of the first embodiment, two columnar bodies are provided as an example, but three or more columnar bodies may be provided.

[0097] (Second Embodiment)

[0098] Fig.18 is a cross-sectional view of an acoustic wave device according to a second embodiment. Fig.18As shown, in the acoustic wave device 200 of the second embodiment, the columnar body 30e has a width that narrows from the cover 24 toward the support substrate 10. The angle θ between the side surface of the columnar body 30e and the upper surface 11 of the support substrate 10 may be, for example, greater than 90° and less than or equal to 130°, greater than or equal to 95° and less than or equal to 120°, or greater than or equal to 100° and less than or equal to 110°. The other configurations of the acoustic wave device 200 are the same as those of the acoustic wave device 100 of the first embodiment, and thus descriptions thereof will be omitted.

[0099] According to the second embodiment, the columnar body 30e has a width that narrows from the cover 24 toward the support substrate 10. The cover 24 is preferably grounded for shielding. In order to improve rigidity, the columnar body 30e is preferably made of metal. In this case, the columnar body 30e is at ground potential. In this case, in order to reduce the parasitic capacitance between the columnar body 30e and the acoustic wave element 15 and the wiring 17, it is preferred that the width of the columnar body 30e narrows from the cover 24 toward the support substrate 10, and the distance between the columnar body 30e and the acoustic wave element 15 and the wiring 17 increases. Here, the columnar body 30e is not electrically connected to the acoustic wave element 15 on the support substrate 10.

[0100] (Third Embodiment)

[0101] Fig.19 is a cross-sectional view of an acoustic wave device according to a third embodiment. Fig.19 As shown, in the acoustic wave device 300 of the third embodiment, the side surface of the piezoelectric layer 13a in the through hole 40 has a cone shape that is tilted toward the support substrate 10. The angle θ between the side surface of the piezoelectric layer 13a and the upper surface 11 of the support substrate 10 from the side surface of the piezoelectric layer 13a may be less than 90° and greater than or equal to 65°, less than or equal to 85° and greater than or equal to 70°, or less than or equal to 80° and greater than or equal to 75°. The other configurations of the acoustic wave device 300 are the same as those of the acoustic wave device 100 of the first embodiment, and thus descriptions thereof will be omitted.

[0102] According to the third embodiment, the side surface of the piezoelectric layer 13a in the through hole 40 is inclined to expand toward the support substrate 10. Thus, the distance between the columnar body 30 and the acoustic wave element 15 and the wiring 17 can be increased, and the parasitic capacitance between the columnar body 30 and the acoustic wave element 15 and the wiring 17 can be reduced.

[0103] Furthermore, in the third embodiment, as in the second embodiment, a columnar body 30 e having a width that becomes narrower from the cover 24 toward the support substrate 10 may be used.

[0104] (Fourth Embodiment)

[0105] Fig. 204 is a cross-sectional view of an acoustic wave device according to a fourth embodiment. In the acoustic wave device 400 of the fourth embodiment, the piezoelectric layer 13b does not have a through hole 40, but has a recess 19 on the upper surface 14. The piezoelectric layer 13b is present on the bottom surface of the recess 19. The columnar body 30 is arranged in the recess 19 between the supporting substrate 10 and the cover 24. For example, one end face of the columnar body 30 is in contact with the bottom surface of the recess 19, and the other end face thereof is in contact with the cover 24. The depth of the recess 19 can be, for example, more than 1 / 4 and less than 3 / 4 of the thickness of the piezoelectric layer 13b, or more than 1 / 3 and less than 2 / 3. The other configurations of the acoustic wave device 400 are the same as those of the acoustic wave device 100 of the first embodiment, and thus descriptions thereof will be omitted.

[0106] According to the third embodiment, the columnar body 30 is provided between the support substrate 10 and the cover 24 in the recess 19 of the piezoelectric layer 13b. Thus, when pressure is applied to the cover 24 and the columnar body 30 is pushed, a load is applied to the bottom surface of the recess 19 of the piezoelectric layer 13b. Therefore, it is possible to suppress the generation of cracks on the upper surface 14 of the piezoelectric layer 13, and it is possible to suppress the degradation of the characteristics of the acoustic wave element 15.

[0107] The height of the columnar body 30 is preferably greater than the distance from the bottom surface of the recess 19 to the upper surface of the interdigital electrode 52 forming the acoustic wave element 15. Thus, even when the cover 24 is flexed, the cover 24 is prevented from contacting the acoustic wave element 15 and deterioration of characteristics is suppressed.

[0108] The columnar body 30 may be in contact with one of the bottom surface of the recess 19 of the piezoelectric layer 13b or the cover 24, but may not be in contact with the other and a gap may be formed. However, in order to effectively reduce the deflection of the cover 24, it is preferred that one end face of the columnar body 30 is in contact with the bottom surface of the recess 19 of the piezoelectric layer 13b, and the other end face thereof is in contact with the cover 24.

[0109] Moreover, in the fourth embodiment, as in the second embodiment, a columnar body 30e having a width that narrows from the cover 24 toward the support substrate 10 may be used. As in the third embodiment, the side surface of the recess 19 may be inclined to expand toward the support substrate 10. Furthermore, in the second to fourth embodiments, as in the first and second modified examples of the first embodiment, a plurality of columns may be provided.

[0110] (Fifth Embodiment)

[0111] Fig.21 is a cross-sectional view of an acoustic wave device according to a fifth embodiment. Fig.21As shown, in the acoustic wave device 500 of the fifth embodiment, the acoustic wave element 15a is provided on the upper surface 11 of the support substrate 10. The piezoelectric layer 83 is provided on the upper surface 11 of the support substrate 10. The lower electrode 82 and the upper electrode 84 are provided to sandwich the piezoelectric layer 83. A space 87 is formed between the lower electrode 82 and the support substrate 10. The region where the lower electrode 82 and the upper electrode 84 face each other to sandwich at least a portion of the piezoelectric layer 83 is a resonance region 86. In the resonance region 86, the lower electrode 82 and the upper electrode 84 excite an acoustic wave of a thickness longitudinal vibration mode in the piezoelectric layer 83. Outside the resonance region 86, a lower wiring 81 is provided on the lower electrode 82, and an upper wiring 85 is provided on the upper electrode 84. Here, an insertion film for increasing the Q value or temperature compensation may be inserted in the peripheral region of the resonance region 86 of the piezoelectric layer 83.

[0112] The lower electrode 82 and the upper electrode 84 are metal films such as ruthenium films. The lower wiring 81 and the upper wiring 85 are metal films such as copper. The piezoelectric layer 83 is, for example, an aluminum nitride layer or a zinc oxide layer. An acoustic reflection film that reflects acoustic waves may be provided instead of the space 87. The acoustic wave element 15a is manufactured by a known method.

[0113] The piezoelectric layer 83 and the like are not provided in the outer peripheral region of the support substrate 10, but the frame body 20 is provided on the support substrate 10 so as to surround the piezoelectric layer 83 and the like. The cover 24 is bonded to the frame body 20. Thus, the acoustic wave element 15a is sealed in the space 27.

[0114] A through hole 90 is formed to penetrate the piezoelectric layer 83, etc. As in the through hole 40 of the first embodiment, the through hole 90 may be provided as an opening in a portion of the piezoelectric layer 83, etc., or may be provided to divide the piezoelectric layer 83, etc. into a plurality of pieces. In the through hole 90, for example, the upper surface 11 of the support substrate 10 is exposed. The columnar body 30 is provided between the support substrate 10 and the cover 24 in the through hole 90. The columnar body 30 is provided separately from the piezoelectric layer 83, etc. One end of the columnar body 30 is in contact with the upper surface 11 of the support substrate 10, and the other end of the columnar body 30 is bonded to the cover 24.

[0115] As in the first and second modifications of the first embodiment, columnar body 30 is disposed at a symmetrical position with respect to the center of gravity of inner region 29 of cover 24. Columnar body 30 may be disposed at the center of gravity of inner region 29 of cover 24 as in the first embodiment.

[0116] As in the first to fourth embodiments, the functional element including the electrode disposed on the surface of the piezoelectric layer may be an acoustic wave device including the interdigitated electrode 52 disposed on the upper surface 14 of the piezoelectric layer 13, 13a or 13b which is a single crystal lithium tantalate layer or a single crystal lithium niobate layer. As in the fifth embodiment, the functional element may be a piezoelectric thin film resonator including the lower electrode 82 and the upper electrode 84 disposed on the upper and lower surfaces of the piezoelectric layer 83. In addition, the functional element may be an element other than the acoustic wave element, or may be a piezoelectric element such as a MEMS (micro-electromechanical system) element. Moreover, in the fifth embodiment, as in the second embodiment, a columnar body 30e whose width narrows from the cover 24 toward the support substrate 10 may be used.

[0117] FIG. 22A to FIG. 22K is a plan view illustrating an example of the shape of a columnar body. FIG. 22A to FIG. 22K In the figure, cross-hatching is added for clarity. Fig.22A and Fig. 22B As shown, the columnar body 30 may have a square or rectangular shape in plan view. Fig. 22C and Fig.22D As shown in the example, the corners of squares and rectangles can be rounded. Fig.22E and Fig.22F As shown, the columnar body 30 may have a rectangular shape with each side protruding outward, or may have a rectangular shape with each side recessed inward. FIG. 22G to FIG. 22I As shown, the columnar body 30 may have a circular, elliptical or diamond shape. Fig.22J As shown, the columnar body 30 may have a cross shape. Figure 22K As shown, the column 30 may be hollow.

[0118] FIG. 23A to FIG. 23G is a side view illustrating an example of the shape of a columnar body. Figures 23A to 23G In the figure, cross-hatching is added for clarity. Fig.23A and 23B As shown, the columnar body 30 may have a square or rectangular shape in a side view. Fig.23C As shown, the columnar body 30 may have a trapezoidal shape whose width decreases from the cover 24 toward the support substrate 10. Fig.23D As shown, the columnar body 30 may have a trapezoidal shape whose width increases from the cover 24 toward the support substrate 10. Fig.23E and 23F As shown, the columnar body 30 may have a shape of two stacked trapezoids. Figure 23G As shown, the columnar body 30 may have a rectangular shape with sides protruding outward.

[0119] Fig.24A and Fig. 24Bis a plan view illustrating an example of the arrangement of the columnar bodies. Fig.24A As shown, the columnar body 30 may be disposed at the outer peripheral edge portion of the inner region 29 of the cover 24. Fig. 24B As shown, the columns 30 may be arranged at the four corners of the interior region 29 of the cover 24 .

[0120] Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.

Claims

1. An electronic device, comprising: A supporting substrate; A piezoelectric layer, the piezoelectric layer is disposed on the supporting substrate; a functional element including an electrode disposed on a surface of the piezoelectric layer opposite to the support substrate; a metal frame, the frame being arranged on the support substrate in a manner of surrounding the piezoelectric layer and the functional element in a plan view; a metal cover, which is disposed on the frame in such a manner as to form a space between the cover and the support substrate, directly faces the functional element through the space, and seals the functional element in the space; as well as A columnar body is disposed between the support substrate and the cover in the space.

2. The electronic device according to claim 1, wherein The piezoelectric layer has a through hole penetrating the piezoelectric layer, and The columnar body is provided between the support substrate and the cover in the through hole.

3. The electronic device according to claim 2, wherein The height of the columnar body is greater than the distance from the upper surface of the support substrate to the upper surface of the electrode.

4. The electronic device according to claim 2, wherein The columnar body is disposed to be separated from the piezoelectric layer.

5. The electronic device according to claim 2, wherein One of the end faces of the columnar body is in contact with the support substrate, and the other of the end faces of the columnar body is in contact with the cover.

6. The electronic device according to claim 1, wherein The cover is grounded, The columnar body is made of metal, and has a width that narrows from the cover toward the support substrate.

7. The electronic device according to claim 1, wherein The columnar body is located at the center of gravity of a region inside the frame of the cover and is provided between the support substrate and the cover.

8. The electronic device according to any one of claims 1 to 7, wherein The support substrate is one of a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate and a silicon substrate, and The piezoelectric layer is one of a single crystal lithium tantalate layer and a single crystal lithium niobate layer.

9. The electronic device according to any one of claims 1 to 7, wherein The functional element is a piezoelectric thin film resonator including a lower electrode and an upper electrode as the electrodes sandwiching the piezoelectric layer.

10. An electronic device, comprising: A supporting substrate; A piezoelectric layer, the piezoelectric layer is disposed on the supporting substrate; a functional element comprising an electrode disposed on a surface of the piezoelectric layer; a metal frame, the frame being arranged on the support substrate in a manner of surrounding the piezoelectric layer and the functional element in a plan view; a metal cover, which is provided on the frame in such a manner as to form a space between the cover and the support substrate and seals the functional element in the space; as well as a columnar body disposed between the support substrate and the cover in the space, One of the end surfaces of the columnar body is in contact with the support substrate, and the other of the end surfaces of the columnar body is in contact with the cover.

11. An electronic device, comprising: A supporting substrate; A piezoelectric layer, the piezoelectric layer is disposed on the supporting substrate; a functional element comprising an electrode disposed on a surface of the piezoelectric layer; a metal frame, the frame being arranged on the support substrate in a manner of surrounding the piezoelectric layer and the functional element in a plan view; a metal cover, which is provided on the frame in such a manner as to form a space between the cover and the support substrate and seals the functional element in the space; as well as a columnar body disposed between the support substrate and the cover in the space, wherein the piezoelectric layer has a concave portion, the piezoelectric layer exists on the bottom surface of the concave portion, and The columnar body is disposed in the recessed portion between the support substrate and the cover.

Images