Elastic wave device and method of manufacturing the same

Abstract

This invention relates to an elastic wave device having a piezoelectric layer. All or part of the resonator forming region in the piezoelectric layer is composed of two or more unique structural regions, and the structure of the hypersonic layer in at least one of the unique structural regions differs from the structure of the hypersonic layer in another unique structural region. In each unique structural region, multiple channels are formed on the hypersonic layer, and these channels are spaced apart from adjacent channels. In the two or more unique structural regions, all channels have the same depth, and in the two or more unique structural regions, the channel width of at least one channel differs from the channel width of another unique structural region. This allows for the appropriate arrangement of two or more unique structural regions with different volume ratios of hypersonic and hyposonic layers without unnecessarily increasing the manufacturing process.

Description

Technical Field

[0001] This invention relates to an elastic wave device suitable for use as a frequency filter in mobile communication devices and the like, and to an improvement in a wafer manufacturing method. Background Technology

[0002] In filters, as a structure, a silicon dioxide layer is formed on a sapphire substrate, and a piezoelectric layer is formed on the silicon dioxide layer, as can be seen in Patent Document 1.

[0003] In the filter shown in Patent Document 1, there are a first region and a second region, and the average thickness of the silicon dioxide layer is different between the two.

[0004] In the technology shown in Patent Document 1, by providing multiple protrusions and recesses at the interface between the sapphire substrate and the silicon dioxide layer, and varying the height of the protrusions, the average thickness of the silicon dioxide layer in the first region differs from the average thickness of the silicon dioxide layer in the second region. This allows the filter to acquire the desired characteristics. More specifically, in this way, high-frequency spurious emissions and frequency-temperature characteristics can be controlled to predetermined values ​​as needed.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-182130 ( Figure 7 ). Summary of the Invention

[0006] However, in the technology shown in Patent Document 1, in the filter manufacturing process, before forming a silicon dioxide layer on the sapphire substrate, it is necessary to form the recesses on the sapphire substrate typically by photolithography and etching, and to make the heights of the protrusions remaining between the recesses different in the first region and the second region by photolithography and etching.

[0007] The main problem to be solved by this invention is how to make an elastic wave device, which is based on a device chip having the following structure: a high-velocity layer is disposed on a support substrate, a low-velocity layer is disposed on the high-velocity layer, and a piezoelectric layer is disposed on the low-velocity layer, so that the elastic wave device can appropriately have two or more unique structural regions with different volume ratios of the low-velocity layer to the high-velocity layer without needlessly increasing the manufacturing process of the elastic wave device.

[0008] To achieve the above-mentioned objectives, under the first viewpoint of the present invention, the main body of the elastic wave device is a device chip having the following structure: including a support substrate, a high-velocity acoustic layer formed on the support substrate, a low-velocity acoustic layer formed on the high-velocity acoustic layer, and a piezoelectric layer formed on the low-velocity acoustic layer; a circuit pattern including an IDT electrode is formed on the surface of the piezoelectric layer of the device chip. Wherein, all or part of the resonator forming region in the piezoelectric layer is composed of two or more unique structural regions arranged along the propagation direction of the surface wave excited by the IDT electrode, and in the two or more unique structural regions, the structure of the hypersonic layer in at least one of the unique structural regions is different from the structure of the hypersonic layer in another of the unique structural regions. In the two or more unique structural regions, multiple channels are formed on the hypersonic layer in a direction orthogonal to the propagation direction, and the multiple channels are formed with a gap between adjacent channels in the propagation direction. In all of the two or more unique structural regions, the depth of the channels is the same; and in the two or more unique structural regions, the width of the channel in at least one of the unique structural regions is different from the width of the channel in another unique structural region, or the distance between adjacent channels in at least one of the unique structural regions is different from the distance between adjacent channels in another unique structural region.

[0009] One embodiment of the present invention is to make the volume ratio of the low-velocity layer to the high-velocity layer in at least one of the unique structural regions different from the volume ratio of the low-velocity layer to the high-velocity layer in another of the unique structural regions.

[0010] In some implementations, the hypersonic layer is composed of materials such as Si, SiN, AlN, and Al2O3.

[0011] In some implementations, the thickness of the hypersonic layer is 2 to 10 μm.

[0012] In some implementations, the material of the low-velocity layer is SiO2.

[0013] In some implementations, the thickness of the low-velocity layer is 0.2 to 2 μm.

[0014] In some embodiments, the sum of the thicknesses of the piezoelectric layer and the low-velocity layer is set to be less than 1λ, and the thickness of the low-velocity layer is set to be between 0.1 and 0.7λ, where λ is the surface wave wavelength.

[0015] In some implementations, the channel width is set to 0.2λ to 0.5λ, where λ is the surface wave wavelength.

[0016] In some implementations, the distance between the channels is set to 0.2λ to 0.5λ, where λ is the surface wave wavelength.

[0017] Furthermore, to achieve the above-mentioned problem, under a second aspect of the present invention, the method for manufacturing the elastic wave device includes: The step of forming a hypersonic film made of a material that serves as the hypersonic layer on one side of the wafer that serves as the support substrate; The step of forming the channel on the hypersonic membrane; The step of forming a low-velocity membrane with a constant thickness, which is made of a material serving as the low-velocity layer, within the channel on the high-velocity membrane; The step of forming the piezoelectric layer on the low-velocity film; And the step of forming the circuit pattern in a region that serves as a chip of the device.

[0018] According to the present invention, since the channel depth formed in the hypersonic layer is not changed directly below the unique structural region, but rather the width of the channel is changed, or the distance between adjacent channels is changed, thereby making the structures of at least two unique structural regions different from each other, or by making the volume ratio of the low-speed layer to the high-speed layer in a certain unique structural region different from other unique structural regions, the elastic wave device can thus possess such a unique structural region. Therefore, the elastic wave device can be appropriately equipped with such a unique structural region without unnecessarily increasing the manufacturing process of the elastic wave device. Attached Figure Description

[0019] Figure 1 This is a top view of the elastic wave device according to the first embodiment.

[0020] Figure 2 yes Figure 1 The cross-sectional structure diagram at the location of line A-A in the diagram.

[0021] Figure 3 yes Figure 2 A cross-sectional view of the location of line B-B in the diagram.

[0022] Figure 4 This is a structural diagram showing an example of a resonator formed on the functional surface of the device chip constituting the elastic wave device.

[0023] Figure 5 This is a top view of the elastic wave device according to the second embodiment.

[0024] Figure 6 yes Figure 5 A cross-sectional view of the C-C line.

[0025] Figure 7 yes Figure 6 A cross-sectional view of the structure at the location of line D-D in the diagram.

[0026] Figure 8 This is a cross-sectional structural diagram of the elastic wave device according to the third embodiment.

[0027] Figure 9 yes Figure 8 A cross-sectional view of the E-E line.

[0028] Figure 10 This is a cross-sectional structural diagram showing one step of the manufacturing process of the aforementioned first embodiment.

[0029] Figure 11 It shows Figure 10 The cross-sectional structure diagram of the next process.

[0030] Figure 12 It shows Figure 11 The cross-sectional structure diagram of the next process.

[0031] Figure 13 It shows Figure 12 The cross-sectional structure diagram of the next process.

[0032] Figure 14 These are simulation results for elastic wave devices.

[0033] Figure label: x direction of propagation y Imaginary line segment z Imaginary plane 1. Elastic wave device 2. Device Chips 2a Functional surface 2b Back 2c Side View 3 Supporting substrate 4 Hypersonic Layer 4a First page 5 Low-speed layer 6 piezoelectric layers 6a Resonator Formation Region 6b Unique structural region 6c General structural region 6d inner surface 7 Resonators 7a IDT electrode 7b Reflector 7c electrode finger 7d busbar 7e electrode finger 7f busbar 8. Ditch 8a Ditch Mouth 8b Ditch bottom 8c distance 8d trench width 9 wafers 10 High-speed sound membrane 11. Low-velocity membrane. Detailed Implementation

[0034] The following is based on Figures 1 to 14 A typical embodiment of the present invention will be described below. The elastic wave device 1 according to this embodiment is suitable for use as a frequency filter in mobile communication devices and the like.

[0035] According to this embodiment, the elastic wave device 1 is mainly a device chip 2, which has the following structure: a supporting substrate 3, a high-velocity acoustic layer 4 formed on the supporting substrate 3, a low-velocity acoustic layer 5 formed on the high-velocity acoustic layer 4, and a piezoelectric layer 6 formed on the low-velocity acoustic layer 5. Simultaneously, a resonator 7 including an IDT electrode 7a is formed on the surface of the piezoelectric layer 6 of the device chip 2. This resonator 7 is used to excite a predetermined surface wave and forms a circuit pattern.

[0036] By utilizing bumps (not shown) or the like, the device chip 2 is mounted on a packaging substrate (not shown), thereby forming a cavity below the resonator 7, thus constituting an elastic wave device 1 with a CSP (Chip Size Package) structure.

[0037] Additionally, a wall layer (not shown) surrounding the resonator 7 is formed on the surface of the piezoelectric layer 6 of the device chip 2, and a capping layer (not shown) is formed on the wall layer, so that it works in conjunction with the wall layer and the piezoelectric layer 6 to form an internal space to accommodate the resonator 7. In this way, an elastic wave device 1 with a WLP (Wafer Level Package) structure can be constructed.

[0038] Typically, the device chip 2 is in the shape of a flat hexahedron, having a functional surface 2a formed by the surface of the piezoelectric layer 6, a back surface 2b opposite to the functional surface 2a, and four side surfaces 2c.

[0039] like Figure 1 As shown, the circuit pattern includes: multiple resonators 7, multiple bump pads (not shown), inter-resonator wiring for connecting the resonators 7 (not shown), and external connection wiring for connecting the resonators 7 and the bump pads (not shown). This type of circuit pattern is typically composed of a conductive metal film formed by photolithography and formed on the functional surface 2a.

[0040] Figure 4An example of the structure of a resonator 7 is shown. The resonator 7 has an IDT electrode 7a and reflectors 7b formed on both sides of the IDT electrode 7a. The IDT electrode 7a is composed of electrode pairs, each electrode pair consisting of multiple electrode fingers 7c arranged in parallel and connected to each other at one end by a busbar 7d, so that its length direction intersects the propagation direction x of the surface wave, which is the dominant mode. The reflector 7b is composed of multiple electrode fingers 7e arranged in parallel and connected between its ends by a busbar 7f, so that its length direction intersects the propagation direction x of the elastic wave.

[0041] The support substrate 3 is typically made of sapphire or Si (silicon).

[0042] like Figure 2 As shown, a high-velocity acoustic layer 4 is formed on the support substrate 3. The high-velocity acoustic layer 4 is made of a material having a higher volume wave velocity than that of the piezoelectric layer 6. The high-velocity acoustic layer 4 is typically made of Si (silicon), SiN (silicon nitride), AlN (aluminum nitride), Al2O3 (aluminum oxide), etc.

[0043] A low-velocity layer 5 is formed on the high-velocity layer 4. The low-velocity layer 5 is made of a material having a lower bulk wave velocity than that of the piezoelectric layer 6. The low-velocity layer 5 is typically made of SiO2 (silicon dioxide) or the like.

[0044] A piezoelectric layer 6 is formed on the low-velocity layer 5. The piezoelectric layer 6 is typically composed of a piezoelectric material such as lithium tantalate or lithium niobate. Furthermore, a circuit pattern including a resonator 7 is formed on the piezoelectric layer 6 (i.e., on the functional surface 2a), the resonator 7 being used to excite a predetermined surface wave (SH wave).

[0045] Typically, the device chip 2 is constructed as a rectangular plate structure with a side length of 0.5 to 1 mm and a thickness of 0.15 to 0.2 mm, and the outline of the functional surface 2a is rectangular when viewed from a direction orthogonal to the functional surface 2a.

[0046] Furthermore, the thickness of the piezoelectric layer 6 is typically 0.2 to 2 μm.

[0047] The thickness of the low-velocity layer 5 is typically 0.2 to 2 μm.

[0048] The thickness of the hypersonic layer 4 is typically 2 to 10 μm.

[0049] The thickness of the support substrate 3 is typically 100 to 200 μm.

[0050] It should be noted that, in the accompanying drawings, the thickness of the constituent elements, etc., are exaggerated in order to facilitate understanding of the structure of the elastic wave device 1.

[0051] In this embodiment, all or part of the resonator forming region 6a in the piezoelectric layer 6 is composed of two or more unique structural regions 6b arranged along the surface wave propagation direction x.

[0052] exist Figures 1 to 3 In the first embodiment shown, when the device chip 2 is viewed from a direction orthogonal to the functional surface 2a, a resonator forming region 6a can be seen formed on the functional surface 2a of the device chip 2, and the resonator forming region 6a is composed of two unique structural regions 6b arranged side by side. In other words, in this embodiment, the entire resonator forming region 6a is composed of two or more unique structural regions 6b.

[0053] On the other hand, Figures 5 to 7 In the second embodiment shown, when the device chip 2 is viewed from a direction orthogonal to the functional surface 2a, it can be seen that two resonator forming regions 6a are formed on the functional surface 2a of the device chip 2, of which only one ( Figure 5 Above it) it consists of two unique structural regions 6b arranged side by side. Figure 5 The internal structure directly below the resonator forming region 6a is the same as in the first embodiment described above. Located in... Figure 5 The resonator forming region 6a below is not a unique structural region 6b, but a general structural region 6c, which does not contain the channel 8 described later. In the illustrated example, in the general structural region 6c, the interface between the piezoelectric layer 6 and the low-velocity layer 5, and the interface between the low-velocity layer 5 and the high-velocity layer 4, are both planes substantially parallel to the functional surface 2a. In other words, in this embodiment, a portion of the resonator forming region 6a is composed of two or more unique structural regions 6b.

[0054] Furthermore, in the two or more unique structural regions 6b, the structure of the hypersonic layer 4 in at least one unique structural region 6b differs from the structure of the hypersonic layer 4 in another unique structural region 6b. In other words, in the two or more unique structural regions 6b, the internal structure of at least one unique structural region 6b resulting from the channel 8 (described later) differs from the internal structure of another unique structural region 6b resulting from the channel 8 (described later).

[0055] It should be noted that, although not shown in the figure, there can be two or more unique structural regions 6b arranged along the surface wave propagation direction x. When there are three or more unique structural regions 6b, it is sufficient that the structures of the hypersonic layers 4 of at least two of them are different from each other as described later. For example, when there are three unique structural regions side by side, the possible situations include: the structures of each hypersonic layer 4 (i.e., the width of the channel 8 or the distance between the channels 8 as described later) are different from each other; or two of the unique structural regions have the same hypersonic layer 4 structure, while the structure of the remaining unique structural region's hypersonic layer 4 is different from the other two.

[0056] In two or more of the aforementioned unique structural regions 6b, a plurality of channels 8 are formed on each of the hypersonic layers 4. These channels 8 extend in a direction orthogonal to the propagation direction x and are spaced apart from adjacent channels 8 in the propagation direction x.

[0057] In the illustrated example, such as Figure 3 As shown, the channel 8 is formed in such a way that when the device chip 2 is viewed from a direction orthogonal to the functional surface 2a, the channel 8 spans a pair of sides along the propagation direction x in the approximately quadrilateral resonator forming region 6a, thereby forming a region for accommodating the approximately quadrilateral resonator 7.

[0058] Additionally, in the illustrated example, such as Figure 1 and Figure 5 As shown, the quadrilateral resonator forming region 6a is bisected by an imaginary line segment y along the propagation direction x, and unique structural regions 6b are formed on both sides of the imaginary line segment y. At the same time, the internal structure of the unique structural region 6b on one side of the imaginary line segment y is different from the internal structure of the unique structural region 6b on the other side.

[0059] Furthermore, in the unique structural regions 6b on both sides of the imaginary line segment y, the channels 8 are arranged side by side with the intervals between adjacent channels 8 being substantially equal.

[0060] Furthermore, in more than two of the aforementioned unique structural regions 6b, the depth of the channel 8 is the same in all regions (see [reference]). Figure 2 In the illustrated example, the channel 8 is a bottomed channel, with its opening 8a located in the hypersonic layer 4, which minimizes the distance between the inner surface 6d of the piezoelectric layer 6 and the channel (this first surface 4a is located on an imaginary plane z parallel to the inner surface 6d of the piezoelectric layer 6, and is configured to sandwich a hyposonic layer 5 of a certain thickness between the two), while the channel bottom 8b is located on the side opposite to the opening 8a.

[0061] Although not shown in the figure, the channel 8 can also be formed as a structure that penetrates the hypersonic layer 4. In this case, the bottom 8b of the channel 8 is formed by the upper surface of the supporting substrate 3.

[0062] Furthermore, in the illustrated example, the depth of the channel 8 formed in the special structural region 6b on one side of the imaginary line segment y, i.e., the distance between the channel opening 8a and the channel bottom 8b, is the same as the depth of the channel 8 formed in the special structural region 6b on the other side of the imaginary line segment y.

[0063] Meanwhile, in this embodiment, in two or more of the unique structural regions 6b, the channel width 8d of at least one unique structural region 6b is different from the channel width 8d of another unique structural region 6b; or, in two or more of the unique structural regions 6b, the distance 8c between adjacent channels 8 in at least one unique structural region 6b is different from the distance 8c between adjacent channels 8 in another unique structural region 6b.

[0064] In this manner, in two or more unique structural regions 6b, the volume ratio of the low-velocity layer 5 to the high-velocity layer 4 in at least one unique structural region 6b is different from the volume ratio of the low-velocity layer 5 to the high-velocity layer 4 in another unique structural region 6b.

[0065] exist Figures 1 to 3 In the first embodiment shown, the channel width 8d of the channel 8 in the special structural region 6b on the left side of the device chip 2 is narrower, while the channel width 8d of the channel 8 in the special structural region 6b on the right side is wider. This results in a smaller volume ratio of the low-velocity layer 5 to the high-velocity layer 4 in the left special structural region 6b, while the volume ratio is larger in the right special structural region 6b.

[0066] Figure 14 Simulation results of the frequency characteristics are shown when substantially identical resonators 7 are formed in two distinct structural regions 6b, respectively, in a structure having the structure described in the first embodiment above.

[0067] Dashed lines indicate, for example Figure 2 Like the unique structural region 6b on the left, the channel width 8d of the channel 8 is smaller, and the characteristics are such that the volume ratio of the low-speed layer 5 to the high-speed layer 4 in the formation layer of the channel 8 is (low-speed layer 5: high-speed layer 4) = 2:8; the solid line represents the characteristics when the volume ratio of the low-speed layer 5 to the high-speed layer 4 is equal in the formation layer of the channel 8.

[0068] When the vertical axis represents admittance and the horizontal axis represents frequency, it can be seen that the spurious (unwanted response) that appears between 1300 MHz and 1400 MHz will shift as the internal structure of the special structure region 6b changes.

[0069] Figure 8 and Figure 9 A third embodiment is shown, with partial modifications to the structure of the first embodiment 2 described above. In this third embodiment, the distance 8c between channels 8 in the unique structural region 6b on the left side of the device chip 2 is wider, while the distance 8c between channels 8 in the unique structural region 6b on the right side is narrower. This results in a smaller volume ratio of the low-velocity layer 5 to the high-velocity layer 4 in the left-side unique structural region 6b, and a larger volume ratio in the right-side unique structural region 6b. The channel width 8d of the channel 8 in the left-side unique structural region 6b is the same as the channel width 8d of the channel 8 in the right-side unique structural region 6b.

[0070] Therefore, according to this embodiment, the elastic wave device 1, directly below the unique structural region 6b, does not need to change the depth of the channel 8 formed in the hypersonic layer 4. Instead, it can have at least two unique structural regions 6b with different internal structures by changing the channel width 8d of the channel 8 or by changing the distance 8c between adjacent channels 8. Since multiple channels 8 can be formed simultaneously in the same step of the manufacturing process of the elastic wave device 1, the elastic wave device 1 can appropriately have more than two unique structural regions 6b without unnecessarily increasing the manufacturing process of the elastic wave device 1.

[0071] Typically, when the wavelength of the surface wave used as the master mode is 1λ, the sum of the thicknesses of the piezoelectric layer 6 and the low-velocity layer 5 is set to be less than 1λ.

[0072] The thickness of the low-velocity layer 5 was set to be between 0.1 and 0.7λ.

[0073] The distance between the first surface 4a of the hypersonic layer 4 and the bottom 8b of the channel 8 is set to 0.025 to 0.675λ.

[0074] In addition, the width 8d of the channel 8 is typically set to 0.2λ to 0.5λ.

[0075] In addition, the distance 8c between adjacent channels 8 is typically set to 0.2λ to 0.5λ.

[0076] The elastic wave device 1 described above, such as Figures 10 to 13 As shown, it can be manufactured appropriately and reasonably by a manufacturing method that includes the following steps.

[0077] First, on one side of the wafer 9, which serves as the support substrate 3, a hypersonic film 10 is formed, which is made of the material used as the hypersonic layer 4. Figure 10 / First process).

[0078] Subsequently, for a region of the device chip 2, within the region of the hypersonic membrane 10 that is the specific structural region 6b, a plurality of channels 8 are formed. Figure 11 / Second process). The multiple channels 8 are generated simultaneously through a single photolithography and etching process, which is completed using a single photomask.

[0079] Next, on the high-velocity membrane 10, a low-velocity membrane 11 of constant thickness, made of the material that serves as the low-velocity layer 5, is formed within the channel 8. Figure 12 (Third step). The low-velocity film 11 is typically formed by plasma CVD. The material of the low-velocity layer 5 not only covers the interior of the channel 8, but is also stacked on the high-velocity film 10 with a constant thickness. In the region where the channel 8 is formed, the interface between the high-velocity film 10 and the low-velocity film 11 exhibits an alternating convex-concave morphology in the surface wave propagation direction x. The opposite side of this interface, i.e., the surface of the low-velocity film 11, is ground to be parallel to one side of the wafer 9.

[0080] Subsequently, a piezoelectric layer 6 is formed on the low-velocity membrane 11. Figure 13 / Fourth process). The piezoelectric layer 6 is formed by bonding a piezoelectric substrate, which serves as the piezoelectric layer, onto the wafer and grinding the side opposite to the bonding surface.

[0081] Next, in the region that serves as the device chip 2, the circuit pattern is formed on the piezoelectric layer 6 (fifth step). Afterward, the wafer 9 is diced and divided into individual pieces that serve as the device chip 2, thereby generating the elastic wave device 1 having the above-described structure.

[0082] Of course, the present invention is not limited to the embodiments described above, but includes all embodiments that can achieve the purpose of the present invention.

Claims

1. An elastic wave device, the main body of which is a device chip having the following structure: including a support substrate, a high-velocity layer formed on the support substrate, a low-velocity layer formed on the high-velocity layer, and a piezoelectric layer formed on the low-velocity layer; A circuit pattern containing an IDT electrode is formed on the surface of the piezoelectric layer of the device chip; Wherein, all or part of the resonator forming region in the piezoelectric layer is composed of two or more unique structural regions arranged along the propagation direction of the surface wave excited by the IDT electrode, and in the two or more unique structural regions, the structure of the hypersonic layer in at least one of the unique structural regions is different from the structure of the hypersonic layer in another of the unique structural regions. In the two or more unique structural regions, multiple channels are formed on the hypersonic layer in a direction orthogonal to the propagation direction, and the multiple channels are formed with a gap between adjacent channels in the propagation direction. In all of the two or more unique structural regions, the depth of the channels is the same; Furthermore, in the two or more unique structural regions, the width of the channel in at least one of the unique structural regions is different from the width of the channel in another unique structural region, or the distance between adjacent channels in at least one of the unique structural regions is different from the distance between adjacent channels in another unique structural region.

2. The elastic wave device according to claim 1, characterized in that: In the two or more unique structural regions, the volume ratio of the low-velocity layer to the high-velocity layer in at least one of the unique structural regions is different from the volume ratio of the low-velocity layer to the high-velocity layer in another of the unique structural regions.

3. The elastic wave device according to claim 1, characterized in that, The hypersonic layer is composed of materials such as Si, SiN, AlN, and Al2O3.

4. The elastic wave device according to claim 1, characterized in that, The thickness of the hypersonic layer is 2 to 10 μm.

5. The elastic wave device according to claim 1, characterized in that, The material of the low-velocity layer is SiO2.

6. The elastic wave device according to claim 1, characterized in that, The thickness of the low-velocity layer is 0.2 to 2 μm.

7. The elastic wave device according to claim 1, characterized in that, The sum of the thicknesses of the piezoelectric layer and the low-velocity layer is set to be less than 1λ, and the thickness of the low-velocity layer is set to be between 0.1 and 0.7λ, where λ is the surface wave wavelength.

8. The elastic wave device according to claim 1, characterized in that, The width of the channel is set to be between 0.2λ and 0.5λ, where λ is the surface wave wavelength.

9. The elastic wave device according to claim 1, characterized in that, Furthermore, the distance between the channels is set to 0.2λ to 0.5λ, where λ is the surface wave wavelength.

10. A method for manufacturing an elastic wave device, characterized in that, The manufacturing method includes: The step of forming a hypersonic film made of a material that serves as the hypersonic layer on one side of the wafer that serves as the support substrate; The step of forming the channel on the hypersonic membrane; The step of forming a low-velocity membrane with a constant thickness, which is made of a material serving as the low-velocity layer, within the channel on the high-velocity membrane; The step of forming the piezoelectric layer on the low-velocity film; And the step of forming the circuit pattern in a region that serves as a chip of the device.

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