Elastic wave device and manufacturing method for elastic wave device

Abstract

To provide an elastic wave device that can suppress lateral mode spurious.SOLUTION: An elastic wave device includes a support substrate, a lower electrode formed on the support substrate, a piezoelectric layer formed on the lower electrode and having at least one first groove formed therein, an upper electrode formed on the piezoelectric layer and being adjacent to the first groove, and an insulator filling the first groove and having a second groove formed therein, the second groove having an inner side surface substantially parallel to a stacking direction of the support substrate and the lower electrode relative to an inner side surface of the first groove.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to an elastic wave device and a method for manufacturing an elastic wave device.

Background Art

[0002] Patent Document 1 discloses an acoustic thin film resonator. The acoustic thin film resonator is a SMR (Solidly Mounted Resonator). According to the acoustic thin film resonator, transverse mode spurs can be suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the acoustic thin film resonator described in Patent Document 1, although it is required to have a vertical or nearly vertical angle as the side surface of the piezoelectric layer, its realization is not easy. When anisotropic reactive ion etching is performed on lithium tantalate or lithium niobate, which is the piezoelectric layer, its cross-sectional shape becomes an inclined surface with a large inclination angle. The same applies when laser etching is used. In this case, in the acoustic thin film resonator, the elastic wave traveling in the horizontal direction is reflected by the inclined surface of the piezoelectric layer, resulting in the generation of transverse mode spurs.

[0005] The present disclosure has been made to solve the above problems. An object of the present disclosure is to provide an elastic wave device and a method for manufacturing an elastic wave device that can more reliably suppress transverse mode spurs.

Means for Solving the Problems

[0006] The elastic wave device according to the present disclosure is A support substrate, a lower electrode formed on the support substrate, a piezoelectric layer formed on the lower electrode and having at least one first groove formed therein, an upper electrode formed on the piezoelectric layer and adjacent to the first groove, an insulator filled in the first groove and having an inner surface that is closer to being parallel to the stacking direction of the support substrate and the lower electrode than the inner surface of the first groove, and having a second groove formed therein, and comprising the same.

[0007] An acoustic reflection layer formed between the support substrate and the lower electrode, is one form of the present disclosure.

[0008] One form of the present disclosure is that the first groove is formed so as to penetrate the piezoelectric layer, the lower electrode, and the acoustic reflection layer.

[0009] The acoustic reflection layer a high acoustic impedance layer formed of hafnium oxide or tungsten, a low acoustic impedance layer formed of silicon dioxide, and being alternately laminated is one form of the present invention.

[0010] The piezoelectric layer has a pair of first grooves, One form of the present invention is that the upper electrode is formed between the pair of first grooves in a plan view.

[0011] A pair of piston bodies formed at outer edge portions of the upper electrode so as to be orthogonal to the pair of first grooves in a plan view, and comprising the same is one form of the present disclosure.

[0012] One form of the present disclosure is that the first groove surrounds the upper electrode in a region excluding a wiring portion connected to the upper electrode in a plan view.

[0013] In one aspect of the present disclosure, the value of the acoustic impedance of the insulator is between 90% and 110% of the value of the acoustic impedance of the piezoelectric layer.

[0014] In one aspect of the present disclosure, the insulator contains silicon, oxygen, and nitrogen.

[0015] A method for manufacturing an elastic wave device according to the present disclosure includes: a lower electrode placement step of placing a lower electrode on a support substrate; a piezoelectric layer placement step of placing a piezoelectric layer on the lower electrode; a first groove formation step of forming a first groove in the piezoelectric layer; an insulator filling step of filling the first groove with an insulator; an upper electrode formation step of forming an upper electrode in a region adjacent to the first groove on the piezoelectric layer; a second groove formation step of forming a second groove in the insulator so that the insulator has an inner surface closer to being parallel to the lamination direction of the support substrate and the lower electrode than the inner surface of the first groove; and includes the above steps.

Advantages of the Invention

[0016] According to the present disclosure, transverse mode spurious can be more reliably suppressed.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0018] The embodiments will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals. The redundant description of such parts will be appropriately simplified or omitted.

[0019] Embodiment 1. FIG. 1 is a sectional view of the elastic wave device in Embodiment 1.

[0020] As shown in FIG. 1, the elastic wave device 1 includes a wiring substrate 2, a chip substrate 3, a plurality of bumps 4, and a sealing portion 5.

[0021] For example, the wiring substrate 2 is a multilayer substrate containing resin. For example, the wiring substrate 2 is a low temperature co-fired ceramics (LTCC) multilayer substrate composed of a plurality of dielectric layers. For example, the wiring substrate 2 incorporates passive elements (not shown) such as capacitors or inductors.

[0022] In FIG. 1, the upper surface of the wiring board 2 is a component mounting surface. A plurality of conductive pads 2A are formed on the upper surface of the wiring board 2. For example, the plurality of conductive pads 2A are formed of copper. The lower surface of the wiring board 2 is a mounting surface to a mother board or the like. A plurality of conductive pads 2B are formed on the lower surface of the wiring board 2. For example, the plurality of conductive pads 2B are formed of copper. A plurality of internal conductors 2C are incorporated in the wiring board 2. For example, the plurality of internal conductors 2C are formed of copper. Each of the internal conductors 2C electrically connects the conductive pads 2A and the conductive pads 2B corresponding to each other.

[0023] The chip board 3 faces the wiring board 2. For example, on the main surface (the lower surface in FIG. 1) of the chip board 3, a receiving filter (not shown in FIG. 1) and a transmitting filter (not shown in FIG. 1) are formed.

[0024] The receiving filter is formed so that an electrical signal in a desired frequency band can pass therethrough. For example, the receiving filter is a ladder-type filter including a plurality of series resonators and a plurality of parallel resonators. For example, each resonator is formed of an elastic wave element.

[0025] The transmitting filter is formed so that an electrical signal in a desired frequency band can pass therethrough. For example, the transmitting filter is a ladder-type filter including a plurality of series resonators and a plurality of parallel resonators. For example, each resonator is formed of an elastic wave element.

[0026] The chip board 3 includes a wiring pattern 3A. The wiring pattern 3A electrically connects a plurality of resonators.

[0027] Each of the plurality of bumps 4 is gold, a conductive adhesive, solder, or the like. For example, the height of the bump 4 is from 20 μm to 50 μm. Each of the plurality of bumps 4 electrically connects the conductive pad 2A and the wiring pattern 3A at corresponding positions.

[0028] The sealing portion 5 hermetically seals the chip substrate 3 together with the wiring substrate 2 while leaving a space 6 between the wiring substrate 2 and the chip substrate 3. For example, the sealing portion 5 is formed of an insulator such as a synthetic resin. The synthetic resin is an epoxy resin, a polyimide, or the like.

[0029] Next, the elastic wave element will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view of the elastic wave element of the elastic wave device according to the first embodiment.

[0030] In FIG. 2, the elastic wave element is an acoustic thin film resonator 8. Specifically, the acoustic thin film resonator 8 is an SMR (Solidly Mounted Resonator).

[0031] For example, the chip substrate 3 includes a support substrate 9 and an acoustic reflection layer 10. For example, the support substrate 9 is formed of sapphire, silicon, alumina, spinel, quartz, or glass. The acoustic reflection layer 10 includes a plurality of high acoustic impedance layers 10A and a plurality of low acoustic impedance layers 10B. In the acoustic reflection layer 10, the high acoustic impedance layers 10A and the low acoustic impedance layers 10B are alternately laminated. For example, the high acoustic impedance layer 10A is formed of hafnium oxide or tungsten. For example, the low acoustic impedance layer 10B is formed of silicon dioxide.

[0032] In the acoustic thin film resonator 8, the piezoelectric layer 8A is formed of lithium tantalate or lithium niobate. The adhesive layer 8B is formed under the piezoelectric layer 8A. For example, the adhesive layer 8B is formed of titanium. The lower electrode 8C and the upper electrode 8D are provided so as to sandwich the piezoelectric layer 8A and the adhesive layer 8B. Specifically, the lower electrode 8C is formed under the adhesive layer 8B. The upper electrode 8D is formed on the piezoelectric layer 8A. A pair of piston bodies 8E are formed on the outer edge of the upper electrode 8D. For example, the lower electrode 8C, the upper electrode 8D, and the pair of piston bodies 8E are formed of aluminum. For example, the lower electrode 8C, the upper electrode 8D, and the pair of piston bodies 8E are formed of an alloy of aluminum and copper.

[0033] The electric separation layer 8F is formed between the piezoelectric layer 8A and the rear end portion of the upper electrode 8D. The inert layer 8G is formed so as to cover the entire area of the pair of piston bodies 8E other than the rear end portion of the upper electrode 8D.

[0034] In the acoustic thin film resonator 8, the lower electrode 8C and the upper electrode 8D excite an elastic wave in the thickness longitudinal vibration mode inside the piezoelectric layer 8A. The elastic wave is reflected by the acoustic reflection layer 10.

[0035] Next, the structure around the elastic wave element will be described with reference to FIGS. 3 and 4. FIG. 3 is a plan view for explaining the structure around the elastic wave element of the elastic wave device in Embodiment 1. FIG. 4 is a perspective view for explaining the structure around the elastic wave element of the elastic wave device in Embodiment 1.

[0036] As shown in FIGS. 3 and 4, a pair of confinement structures 11 are formed around the elastic wave element. The upper electrode 8D is formed between the pair of confinement structures 11 in a plan view. The pair of piston bodies 8E are formed so as to be orthogonal to the pair of confinement structures 11 respectively in a plan view.

[0037] Next, the confinement structure 11 will be described with reference to FIG. 5. FIG. 5 is a cross-sectional view for explaining the confinement structure of the elastic wave device in Embodiment 1.

[0038] A in FIG. 5 shows a first example of the confinement structure 11. B in FIG. 5 shows a second example of the confinement structure 11. C in FIG. 5 shows a third example of the confinement structure 11. D in FIG. 5 shows a fourth example of the confinement structure 11. E in FIG. 5 shows a fifth example of the confinement structure 11.

[0039] As shown in A to E of FIG. 5, the confinement structure 11 includes a first groove 12. In the confinement structure 11, the insulator 13 is filled in the first groove 12. The insulator 13 includes a second groove 14.

[0040] The depth of the first groove 12 is set as appropriate. For example, as shown in A of FIG. 5, the first groove 12 is formed to reach from the piezoelectric layer 8A to the boundary between the piezoelectric layer 8A and the adhesive layer 8B. For example, as shown in B of FIG. 5, the first groove 12 is formed to reach from the piezoelectric layer 8A to the center in the vertical direction of the lower electrode 8C. For example, as shown in C of FIG. 5, the first groove 12 is formed to reach from the piezoelectric layer 8A to the boundary between the high acoustic impedance layer 10A and the low acoustic impedance layer 10B at the center in the vertical direction of the acoustic reflection layer 10. For example, as shown in D of FIG. 5, the first groove 12 is formed to reach from the piezoelectric layer 8A to the boundary between the lower high acoustic impedance layer 10A and the support substrate 9. For example, as shown in E of FIG. 5, the first groove 12 is formed to reach from the piezoelectric layer 8A to the center in the vertical direction of the support substrate 9.

[0041] Next, with reference to FIG. 6, the relationship between the first groove 12, the second groove 14, and the transverse-mode elastic wave will be described. FIG. 6 is a diagram for explaining the relationship between the first groove, the second groove, and the transverse-mode elastic wave formed in the elastic wave device according to the first embodiment.

[0042] A of FIG. 6 is a diagram schematically enlarging the main part when the insulator 13 is not filled in the first groove 12 in E of FIG. 5. B of FIG. 6 is a diagram schematically enlarging the main part in E of FIG. 5.

[0043] In A of FIG. 6, the first groove 12 is formed outside the upper electrode 8D. The first groove 12 is formed by anisotropic reactive ion etching or laser etching. Therefore, the inner surface of the first groove 12 is formed to be inclined. For example, the inner surface of the first groove 12 is formed to be inclined by an angle α with respect to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A. For example, the angle α is about 15 degrees to 30 degrees.

[0044] If the elastic wave element operates in this state, the elastic wave in the transverse mode travels horizontally inside the piezoelectric layer 8A toward the inner surface of the first groove 12 as indicated by the arrow W1. Then, the elastic wave in the transverse mode reaches the inner surface of the first groove 12. Here, the values of the acoustic impedances of the piezoelectric layer 8A and air are significantly different. Therefore, most of the elastic wave in the transverse mode is reflected at the boundary between the piezoelectric layer 8A and air. Further, the inner surface of the first groove 12 is inclined by an angle α with respect to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A. For this reason, the elastic wave reflected at the boundary between the piezoelectric layer 8A and air travels obliquely downward inside the piezoelectric layer 8A as indicated by the arrow W2. The elastic wave includes a vertical component. Due to the influence of the vertical component of the elastic wave, a broadband confinement effect cannot be obtained, and transverse mode spurs are generated.

[0045] Therefore, in the present embodiment, as shown in B of FIG. 6, the insulator 13 is filled in the first groove 12. Then, the second groove 14 is formed. For example, the second groove 14 is formed by anisotropic reactive ion etching. The second groove 14 has an inner surface that is closer to being parallel to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A than the inner surface of the first groove 12. Specifically, the inner surface of the second groove 14 is substantially parallel to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A.

[0046] The insulator 13 is formed of a material that can make the inner surface of the second groove 14 substantially parallel to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A. For example, the insulator 13 is formed of a compound of silicon, oxygen, and nitrogen. In the insulator 13, the composition ratio of silicon, oxygen, and nitrogen is set so that the value of its own acoustic impedance approaches the value of the acoustic impedance of the piezoelectric layer 8A as much as possible. For example, the value of the acoustic impedance of the insulator 13 is between 90% and 110% of the value of the acoustic impedance of the piezoelectric layer 8A.

[0047] Here, the speed of sound in lithium tantalate is 4200 m / s. The density of lithium tantalate is 7460 kg / m 3 . Therefore, the acoustic impedance of lithium tantalate is 31.33×10 6 kg / m 2 ·s. The speed of sound in lithium niobate is 3800 m / s. The density of lithium niobate is 4650 kg / m 3 . Therefore, the acoustic impedance of lithium niobate is 17.67×10 6 kg / m 2 ·s.

[0048] In contrast, the speed of sound in silicon dioxide is 5740 m / s. The density of silicon dioxide is 2650 kg / m 3 . Therefore, the acoustic impedance of silicon dioxide is 15.21×10 6 kg / m 2 ·s. The speed of sound in silicon nitride is 11780 m / s. The density of silicon nitride is 3440 kg / m 3 . Therefore, the acoustic impedance of silicon nitride is 40.52×10 6 kg / m 2 ·s.

[0049] Taking these specific numerical values into account, in the insulator 13, the composition ratio of silicon, oxygen, and nitrogen is set so that the value of the acoustic impedance approaches the value of the acoustic impedance of the piezoelectric layer 8A as closely as possible.

[0050] When the elastic wave element operates in this state, the elastic wave in the transverse mode travels horizontally inside the piezoelectric layer 8A toward the inner surface of the first groove 12 as indicated by the arrow W3. Then, the elastic wave in the transverse mode reaches the inner surface of the first groove 12. Here, the values of the acoustic impedances of the piezoelectric layer 8A and the insulator 13 are close. Therefore, most of the elastic wave in the transverse mode transmits through the boundary between the piezoelectric layer 8A and the insulator 13 with almost no reflection. Then, the elastic wave in the transverse mode travels horizontally inside the insulator 13 toward the inner surface of the second groove 14 as indicated by the arrow W4. Then, the elastic wave in the transverse mode reaches the inner surface of the second groove 14. Here, the values of the acoustic impedances of the insulator 13 and the air are significantly different. Therefore, most of the elastic wave in the transverse mode reflects at the boundary between the insulator 13 and the air. However, the inner surface of the second groove 14 is substantially parallel to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A. Therefore, most of the elastic wave reflected at the boundary between the insulator 13 and the air travels horizontally inside the insulator 13 toward the inner surface of the first groove 12 as indicated by the arrow W5. Then, the elastic wave reaches the inner surface of the second groove 14. Here, the values of the acoustic impedances of the insulator 13 and the piezoelectric layer 8A are close. Therefore, most of the elastic wave transmits through the boundary between the insulator 13 and the piezoelectric layer 8A with almost no reflection. Then, most of the elastic wave travels horizontally inside the piezoelectric layer 8A as indicated by the arrow W6.

[0051] As described above, in this embodiment, the elastic wave in the transverse mode transmits through the boundary between the piezoelectric layer 8A and the insulator 13, reflects at the boundary between the insulator 13 and the air, and after transmitting through the boundary between the insulator 13 and the piezoelectric layer 8A, hardly contains a vertical component. Therefore, a broadband confinement effect is obtained, and the generation of transverse mode spurious is suppressed.

[0052] Next, a method for manufacturing the main part of the elastic wave device 1 will be described with reference to FIGS. 7 to 9. Figs. 7 to 9 are diagrams for explaining a method of manufacturing a main part of an elastic wave device according to Embodiment 1. The left sides of Figs. 8 and 9 are cross-sectional views taken along line A-A in Fig. 3. The right sides of Figs. 8 and 9 are cross-sectional views taken along line B-B in Fig. 3.

[0053] As shown in Fig. 7, on the side of the support substrate 9, a high acoustic impedance layer 10A is formed on the support substrate 9. Then, a low acoustic impedance layer 10B is formed on the high acoustic impedance layer 10A. Then, a high acoustic impedance layer 10A is formed on the low acoustic impedance layer 10B. Then, a low acoustic impedance layer 10B is formed on the high acoustic impedance layer 10A. Then, chemical mechanical polishing is performed on the uppermost low acoustic impedance layer 10B.

[0054] On the side of the piezoelectric layer 8A, an adhesive layer 8B is formed on the piezoelectric layer 8A. Then, a lower electrode 8C is formed on the adhesive layer 8B. Then, a low acoustic impedance layer 10B is formed on the lower electrode 8C. Then, chemical mechanical polishing is performed on the uppermost low acoustic impedance layer 10B.

[0055] Then, a lower electrode placement step and a piezoelectric layer placement step are performed. Specifically, with the laminate on the side of the piezoelectric layer 8A turned upside down, the low acoustic impedance layer 10B on the side of the support substrate 9 and the low acoustic impedance layer 10B on the side of the piezoelectric layer 8A are joined. As a result, the lower electrode 8C is disposed above the support substrate 9. The piezoelectric layer 8A is disposed above the lower electrode 8C.

[0056] Then, as shown at A in Fig. 8, a first groove forming step and an insulator filling step are performed.

[0057] In the first groove forming step, first, a resist is patterned. Then, dry etching or laser etching is performed. As a result, a first groove 12 is formed. At this time, the inner surface of the first groove 12 becomes an inclined surface having a certain angle. Then, the resist is removed.

[0058] In the insulator filling process, an insulating film is entirely formed on the upper surface of the piezoelectric layer 8A. Thereafter, chemical mechanical polishing is performed on the insulating film until the piezoelectric layer 8A is exposed. As a result, the insulator 13 is filled in the first groove 12.

[0059] Thereafter, as shown in B of FIG. 8, an electrical separation layer forming process is performed. In the electrical separation layer forming process, an electrical separation layer 8F is formed.

[0060] Thereafter, as shown in C of FIG. 8, an upper electrode forming process is performed. In the upper electrode forming process, the upper electrode 8D is formed by a lift-off method in a region adjacent to the first groove 12 on the piezoelectric layer 8A. Specifically, first, a resist is patterned. Thereafter, a metal is deposited. Thereafter, the resist is removed, thereby forming the upper electrode 8D.

[0061] Thereafter, as shown in D of FIG. 8, a piston body forming process is performed. In the piston body forming process, a pair of piston bodies 8E are formed by a lift-off method. Specifically, first, a resist is patterned. Thereafter, a metal is deposited. Thereafter, the resist is removed, thereby forming a pair of piston bodies 8E.

[0062] Thereafter, as shown in A of FIG. 9, an inert layer forming process is performed. In the inert layer forming process, first, an inert film is formed. Thereafter, a resist is patterned. Thereafter, dry etching is performed. Thereafter, the resist is removed. As a result, an inert layer 8G is formed.

[0063] Thereafter, as shown in B of FIG. 9, a wiring pattern forming process is performed. In the wiring pattern forming process, a wiring pattern 3A is formed by a lift-off method. Specifically, first, a resist is patterned. Thereafter, a metal is deposited. Thereafter, the resist is removed, thereby forming the wiring pattern 3A in a state of being electrically connected to the rear end portion of the upper electrode 8D.

[0064] After that, as shown in C of FIG. 9, a second groove forming step is performed. In the second groove forming step, the resist is patterned. After that, anisotropic reactive ion etching is performed. As a result, a second groove 14 is formed in the insulator 13. At this time, the inner surface of the second groove 14 becomes a substantially vertical surface. After that, the resist is removed.

[0065] According to the first embodiment described above, in the insulator 13, the second groove 14 has an inner surface that is closer to being parallel to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A than the inner surface of the first groove 12. At this time, at the boundary between the piezoelectric layer 8A and the insulator 13, there is almost no reflection of elastic waves. Further, the elastic waves reflected at the boundary between the insulator 13 and the air contain almost no vertical component. Therefore, the transverse mode spurious can be more reliably suppressed.

[0066] Further, the acoustic reflection layer 10 is formed between the support substrate 9 and the lower electrode 8C. Therefore, the transverse mode spurious can be more reliably suppressed for the SMR type acoustic thin film resonator 8.

[0067] Further, the first groove 12 is formed so as to penetrate the piezoelectric layer 8A, the adhesive layer 8B, the lower electrode 8C, and the acoustic reflection layer 10. Therefore, the transverse mode spurious can be more reliably suppressed for the SMR type acoustic thin film resonator 8.

[0068] Further, in the acoustic reflection layer 10, the high acoustic impedance layer 10A and the low acoustic impedance layer 10B are alternately laminated. For example, the high acoustic impedance layer 10A is formed of hafnium oxide or tungsten. For example, the low acoustic impedance layer 10B is formed of silicon dioxide. Therefore, the bonding strength of the insulator 13 to the peripheral structure of the first groove 12 can be ensured by the low acoustic impedance layer 10B.

[0069] Further, the upper electrode 8D is formed between the pair of first grooves 12 in a plan view. Therefore, the transverse mode spurious can be more reliably suppressed.

[0070] Also, a pair of piston bodies 8E are formed on the outer edge of the upper electrode 8D so as to be orthogonal to the pair of first grooves 12 in a plan view. Therefore, transverse mode spurious can be more reliably suppressed.

[0071] Also, the value of the acoustic impedance of the insulator 13 is within ±10% of the value of the acoustic impedance of the piezoelectric layer 8A. Therefore, reflection of elastic waves at the boundary between the piezoelectric layer 8A and the insulator 13 can be more reliably suppressed. As a result, transverse mode spurious can be more reliably suppressed.

[0072] Also, the insulator 13 contains silicon, oxygen, and nitrogen. Therefore, the values of the acoustic impedances of the piezoelectric layer 8A and the insulator 13 can be easily made closer. As a result, reflection of elastic waves at the boundary between the piezoelectric layer 8A and the insulator 13 can be more reliably suppressed.

[0073] Embodiment 2. FIG. 10 is a plan view of an elastic wave element of an elastic wave device according to Embodiment 2. In addition, the same reference numerals are assigned to the same or corresponding parts as those in Embodiment 1, and the description of those parts is omitted.

[0074] As shown in FIG. 10, the confinement structure 11 is formed so as to surround the upper electrode 8D (not shown in FIG. 9) in a region excluding the wiring pattern 3A (wiring portion) connected to the upper electrode 8D in a plan view. The confinement structure 11 has the same structure as that in Embodiment 1. Although not shown in FIG. 10, specifically, the confinement structure 11 includes the first groove 12. In the confinement structure 11, the insulator 13 is filled in the first groove 12. The insulator 13 includes a second groove 14. The second groove 14 has an inner surface that is closer to being parallel to the stacking direction of the support substrate 9, the acoustic reflection layer 10, the lower electrode 8C, the adhesive layer 8B, and the piezoelectric layer 8A than the inner surface of the first groove 12.

[0075] According to Embodiment 2 described above, the confinement structure 11 is formed so as to surround the upper electrode 8D in a region excluding the wiring pattern 3A connected to the upper electrode 8D in a plan view. Therefore, transverse mode spurious can be more reliably suppressed.

[0076] Embodiment 3. FIG. 11 is a longitudinal sectional view of a module to which the surface acoustic wave device in Embodiment 3 is applied. Note that the same reference numerals are given to the same or corresponding parts as those in Embodiment 1, and the description of those parts is omitted.

[0077] In FIG. 11, the module 100 includes a wiring substrate 101, an integrated circuit component 102, a surface acoustic wave device 1, an inductor 103, and a sealing portion 104.

[0078] The wiring substrate 101 is equivalent to the wiring substrate 2 in Embodiment 1. The integrated circuit component 102 is mounted inside the wiring substrate 101. The integrated circuit component 102 includes a switching circuit and a low-noise amplifier. The surface acoustic wave device 1 is mounted on the main surface of the wiring substrate 101. The inductor 103 is mounted on the main surface of the wiring substrate 101. The inductor 103 is mounted for impedance matching. For example, the inductor 103 is an Integrated Passive Device (IPD). The sealing portion 104 seals a plurality of electronic components including the surface acoustic wave device 1.

[0079] According to Embodiment 3 described above, the module 100 includes the surface acoustic wave device 1. Therefore, it is possible to realize the module 100 including the surface acoustic wave device 1 in which transverse mode spurious is suppressed.

[0080] Although some aspects of at least one embodiment have been described, it should be understood that various modifications, corrections, and improvements can be easily conceived by those skilled in the art. Such modifications, corrections, and improvements are intended to be part of the present disclosure and are intended to be within the scope of the present disclosure.

[0081] It should be understood that the embodiments of the methods and apparatuses described herein are not limited to the details of the structures and arrangements of the components described in the above description or illustrated in the accompanying drawings. The methods and apparatuses can be implemented in other embodiments and can be carried out or executed in various manners.

[0082] Specific implementation examples are provided herein for illustrative purposes only and are not intended to be limiting.

[0083] The expressions and terms used in this disclosure are for explanatory purposes and should not be regarded as limiting. The use of "including", "comprising", "having", "containing" and variations thereof herein means the inclusion of the items listed hereinafter and their equivalents as well as additional items.

[0084] References to "or" shall be construed as meaning any term described using "or" can represent one, more than one, and all of the terms described therein.

[0085] References to front and back, left and right, top and bottom, horizontal and vertical, front and back are all for the convenience of description. Such references do not limit the components of the present disclosure to any one positional or spatial orientation. Therefore, the above description and drawings are merely illustrative.

Description of Reference Numerals

[0086] 1 Elastic wave device, 2 Wiring substrate, 2A Conductive pad, 2B Conductive pad, 2C Internal conductor, 3 Chip substrate, 3A Wiring pattern, 4 Bump, 5 Sealing portion, 6 Space, 8 Acoustic thin film resonator, 8A Piezoelectric layer, 8B Adhesive layer, 8C Lower electrode, 8D Upper electrode, 8E Piston body, 8F Electrical isolation layer, 8G Inactive layer, 9 Support substrate, 10 Acoustic reflection layer, 10A High acoustic impedance layer, 10B Low acoustic impedance layer, 11 Confining structure, 12 First groove, 13 Insulator, 14 Second groove, 100 Module, 101 Wiring substrate, 102 Integrated circuit component, 103 Inductor, 104 Sealing portion

Claims

1. A support substrate, A lower electrode formed on the support substrate, A piezoelectric layer formed on the lower electrode and having at least one first groove formed therein, An upper electrode formed on the piezoelectric layer and adjacent to the first groove, An insulator filled in the first groove and having an inner surface closer to being parallel to the lamination direction of the support substrate and the lower electrode than the inner surface of the first groove, An acoustic wave device comprising the above.

2. An acoustic reflection layer formed between the support substrate and the lower electrode, The acoustic wave device according to Claim 1, comprising the above.

3. The acoustic wave device according to Claim 2, wherein the first groove is formed to penetrate the piezoelectric layer, the lower electrode, and the acoustic reflection layer.

4. The acoustic reflection layer is A high acoustic impedance layer formed of hafnium oxide or tungsten, A low acoustic impedance layer formed of silicon dioxide, The acoustic wave device according to Claim 2, in which the above are alternately laminated.

5. The piezoelectric layer has a pair of first grooves, The acoustic wave device according to Claim 1, wherein the upper electrode is formed between the pair of first grooves in plan view.

6. A pair of piston bodies formed at the outer edge of the upper electrode so as to be orthogonal to the pair of first grooves in plan view, The acoustic wave device according to Claim 5, comprising the above.

7. The acoustic wave device according to Claim 1, wherein the first groove surrounds the upper electrode in a region excluding the wiring portion connected to the upper electrode in plan view.

8. The acoustic wave device according to Claim 1, wherein the value of the acoustic impedance of the insulator is between 90% and 110% of the value of the acoustic impedance of the piezoelectric layer.

9. The acoustic wave device according to Claim 8, wherein the insulator contains silicon, oxygen, and nitrogen.

10. A lower electrode arrangement step of arranging a lower electrode on a support substrate, A piezoelectric layer arrangement step of arranging a piezoelectric layer on the lower electrode, A first groove formation step of forming a first groove in the piezoelectric layer, An insulator filling step of filling the first groove with an insulator, An upper electrode formation step of forming an upper electrode in a region adjacent to the first groove on the piezoelectric layer, A second groove formation step of forming a second groove in the insulator so as to have an inner surface closer to being parallel to the lamination direction of the support substrate and the lower electrode than the inner surface of the first groove, A method for manufacturing an acoustic wave device comprising the above.

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