Electronic device and method for manufacturing electronic device

Abstract

An electronic device (1) comprises: a substrate (10) having main surfaces (10a and 10b) facing each other; an electronic device disposed on the substrate (10); a planar electrode (20) electrically connected to the electronic device and disposed on the main surface (10a); an adhesion layer (31) made of a first metal material of which the planar electrode (20) is also made and having an amorphous structure; and a metal layer (32) made of a second metal material different from the first metal material and having an amorphous structure. The planar electrode (20), the adhesion layer (31), and the metal layer (32) are disposed in this order from the main surface (10a).

Description

Electronic device and method for manufacturing the same

[0001] The present invention relates to electronic devices and methods for manufacturing electronic devices.

[0002] Patent Document 1 discloses a method for manufacturing an electronic device (electronic equipment) in which a conductive film formed from conductive ink applied to a printing cylinder is brought into contact with a wiring pattern formed on the surface of a substrate, and the conductive film is transferred to the wiring pattern, and the electronic device (electronic equipment) is also disclosed.

[0003] Japanese Patent Application Laid-Open No. 2016-219508

[0004] However, in the electronic device disclosed in Patent Document 1, the conductive film transferred onto the wiring pattern contains impurities such as solvents, metal particles, and dispersants, which are components of the ink, and this raises concerns that the bonding quality of the conductive film transferred onto the wiring pattern may deteriorate.

[0005] Therefore, an object of the present invention is to provide an electronic device having a conductive film with high bonding quality and a method for manufacturing the electronic device.

[0006] In order to achieve the above-mentioned object, an electronic device according to one embodiment of the present invention comprises a substrate having a first main surface and a second main surface facing each other, an electronic device arranged on the substrate, a planar electrode electrically connected to the electronic device and arranged on the first main surface, an adhesion layer made of the same first metal material as the planar electrode and having an amorphous structure, and a metal layer made of a second metal material different from the first metal material and having an amorphous structure, wherein the planar electrode, the adhesion layer, and the metal layer are arranged in this order from the first main surface.

[0007] Furthermore, a method for manufacturing an electronic device according to one aspect of the present invention comprises a substrate having a first main surface and a second main surface facing each other, an electronic device disposed on the substrate, a planar electrode electrically connected to the electronic device and disposed on the first main surface, an adhesion layer made of the same first metal material as the planar electrode and having an amorphous structure, and a metal layer made of a second metal material different from the first metal material and having an amorphous structure, wherein the planar electrode, the adhesion layer, and the metal layer are arranged in this order from the first main surface.

[0008] According to the present invention, it is possible to provide an electronic device having a conductive film with high bonding quality and a method for manufacturing the electronic device.

[0009] FIG. 1 is a cross-sectional view of an electronic device according to an embodiment. FIG. 2 is a cross-sectional view of a transfer sheet according to an embodiment. FIG. 3 is a cross-sectional view of an electronic device according to a first modified example of an embodiment. FIG. 4 is a cross-sectional view of a transfer sheet according to a first modified example of an embodiment. FIG. 5A is a plan view of a transfer sheet according to a first modified example of an embodiment. FIG. 5B is a plan view of a transfer sheet according to a second modified example of an embodiment. FIG. 5C is a plan view of a transfer sheet according to a third modified example of an embodiment. FIG. 6A is a diagram illustrating a first step of a manufacturing method for an electronic device according to an embodiment. FIG. 6B is a diagram illustrating a second step of a manufacturing method for an electronic device according to an embodiment. FIG. 6C is a diagram illustrating a third step of a manufacturing method for an electronic device according to an embodiment. FIG. 7A is an electron diffraction pattern of an amorphous film observed with a scanning transmission electron microscope. FIG. 7B is an electron diffraction pattern of a single crystalline film observed with a scanning transmission electron microscope.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangements, and connection forms shown in the following embodiments are merely examples and are not intended to limit the present invention. Among the components in the following embodiments, components that are not recited in independent claims will be described as optional components. Furthermore, the sizes or size ratios of the components shown in the drawings are not necessarily strict.

[0011] It should be noted that the drawings are schematic diagrams in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present invention, and are not necessarily strictly illustrated, and may differ from the actual shapes, positional relationships, and proportions. In the drawings, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0012] In the component placement of the present disclosure, "a component is placed on a substrate" includes a component being placed on the main surface of the substrate and a component being placed within the substrate. "A component is placed on the main surface of the substrate" includes a component being placed in contact with the main surface of the substrate, as well as a component being placed above the main surface without contacting the main surface (for example, a component being stacked on another component placed in contact with the main surface). "A component is placed on the main surface of the substrate" may also include a component being placed in a recess formed in the main surface. "A component is placed within the substrate" includes a component being encapsulated within a module substrate, as well as a component being entirely placed between both main surfaces of the substrate but partially not covered by the substrate, and a component being only partially placed within the substrate.

[0013] In the component arrangement of the present disclosure, "layer A is joined to layer B" means that layer A and layer B are in contact with each other without any other layer interposed therebetween.

[0014] In the circuit configuration of the present disclosure, "connected" includes not only direct connection by electrodes and / or wiring conductors, but also electrical connection via matching elements such as inductors and capacitors, and switch circuits. "Connected between A and B" means connected to both A and B between A and B.

[0015] Furthermore, terms indicating the relationship between elements, such as "parallel" and "perpendicular," terms indicating the shape of elements, such as "rectangle," and numerical ranges do not only represent strict meanings, but also include substantially equivalent ranges, for example, including an error of a few percent.

[0016] 1 is a cross-sectional view of an electronic device 1 according to an embodiment. As shown in the figure, the electronic device 1 includes a substrate 10, a planar electrode 20, an adhesion layer 31, a metal layer 32, a via conductor 11, an acoustic wave element 2, and electrodes 21, 61, and 62.

[0017] The substrate 10 has opposing main surfaces 10a (first main surface) and 10b (second main surface). As the substrate 10, for example, a low temperature co-fired ceramics (LTCC) substrate having multiple dielectric layers, a high temperature co-fired ceramics (HTCC) substrate, a component-embedded substrate, a substrate having a redistribution layer (RDL), a printed circuit board, or the like can be used.

[0018] An insulating film 12 may be disposed on the main surface 10a of the substrate 10. By disposing the insulating film 12, it is possible to prevent adjacent planar electrodes 20 from short-circuiting.

[0019] The via conductor 11 is an electrode disposed on the substrate 10 from the principal surface 10a toward the principal surface 10b. The via conductor 11 is a through electrode filled in a cavity penetrating the substrate 10 between the principal surface 10a and the principal surface 10b. The via conductor 11 is made of, for example, a metal member containing copper (Cu) as its main component. Note that the via conductor 11 does not have to be a single via conductor extending from the principal surface 10a to the principal surface 10b, and may have a configuration in which multiple via conductors are connected via planar electrodes formed in the substrate 10.

[0020] The planar electrode 20 is a conductive electrode layer that extends along the main surface 10a (xy plane) and is disposed on the main surface 10a. The planar electrode 20 is made of the same first metal material as the via conductors 11, such as copper (Cu).

[0021] The adhesion layer 31 is made of the same first metal material as the planar electrode 20 and has an amorphous structure. The adhesion layer 31 is bonded to the planar electrode 20 and is made of, for example, copper (Cu). The adhesion layer 31 may be a single-element metal layer or an alloy layer made of multiple elements. In other words, the first metal material includes a single-element material or a material composed of multiple elements. When the planar electrode 20 and the adhesion layer 31 are made of the same combination of elements, the composition ratio of the multiple elements making up the planar electrode 20 is the same as the composition ratio of the multiple elements making up the adhesion layer 31.

[0022] The metal layer 32 is made of a second metal material different from the first metal material and has an amorphous structure. The metal layer 32 is bonded to the adhesion layer 31 and is made of, for example, nickel (Ni). The metal layer 32 may be a single-element metal or an alloy made of multiple elements. In other words, the second metal material includes a single-element material or a material made of multiple elements. When the metal layer 32 and the adhesion layer 31 are made of the same combination of multiple elements, the composition ratio of the multiple elements making up the metal layer 32 is different from the composition ratio of the multiple elements making up the adhesion layer 31.

[0023] The planar electrode 20, the adhesive layer 31, and the metal layer 32 are arranged in this order from the main surface 10a.

[0024] Acoustic wave element 2 is an example of an electronic device and includes piezoelectric layer 50, upper electrode 51, lower electrode 52, and support substrate 40. Acoustic wave element 2 is disposed on main surface 10b of substrate 10, out of main surfaces 10a and 10b.

[0025] The support substrate 40 is a substrate, such as a silicon substrate, for supporting the lower electrode 52, the piezoelectric layer 50, and the upper electrode 51. The support substrate 40 has a cavity in the region that contacts the lower electrode 52. This allows the piezoelectric layer 50 to vibrate freely.

[0026] The lower electrode 52 is disposed on one major surface of the support substrate 40. The upper electrode 51 is disposed on one major surface of the support substrate 40. The lower electrode 52 and the upper electrode 51 are made of a material, for example, Al containing 1% Cu.

[0027] The piezoelectric layer 50 is disposed between the lower electrode 52 and the upper electrode 51 and is bonded to the lower electrode 52 and the upper electrode 51. The piezoelectric layer 50 is mainly composed of at least one of zinc oxide (ZnO), aluminum nitride (AlN), lead zirconate titanate (PZT), potassium niobate (KN), lithium niobate (LN), lithium tantalate (LT), quartz crystal, and lithium borate (LiBO).

[0028] Acoustic wave element 2 having the above-described laminated structure generates resonance by inducing bulk acoustic waves in piezoelectric layer 50 by applying electrical energy between lower electrode 52 and upper electrode 51. The bulk acoustic waves generated by the resonance of acoustic wave element 2 propagate between lower electrode 52 and upper electrode 51 in a direction perpendicular to the film surface of piezoelectric layer 50. In other words, acoustic wave element 2 is a resonator that utilizes bulk acoustic waves.

[0029] Electrodes 61 are electrodes for inputting and outputting high-frequency signals to and from acoustic wave element 2. One electrode 61 (e.g., electrode 61 on the left side in FIG. 1 ) is connected to upper electrode 51, and the other electrode 61 (e.g., electrode 61 on the right side in FIG. 1 ) is connected to lower electrode 52. Insulating film 53 is formed on piezoelectric layer 50 and serves to insulate upper electrode 51 from the other electrode 61. Electrodes 21 and 62 are disposed on main surface 10b and serve to electrically connect acoustic wave element 2 and planar electrode 20. Furthermore, the arrangement of electrodes 21, 61, and 62 ensures a space between substrate 10 and acoustic wave element 2.

[0030] The electronic device disposed on the principal surface 10b is not particularly limited. For example, the acoustic wave element 2 may be a laterally excited bulk acoustic resonator (XBAR). In this case, instead of the laminated structure of the upper electrode 51, the piezoelectric layer 50, and the lower electrode 52, the acoustic wave element 2 includes an interdigital transducer (IDT) electrode, a piezoelectric film, an intermediate layer, a cavity, and a support substrate 40. The IDT electrode, the piezoelectric film, the intermediate layer, and the support substrate 40 are laminated in this order from the positive direction of the z-axis to the negative direction of the z-axis. When the principal surface of the support substrate 40 is viewed in plan, a cavity is provided between the piezoelectric film and the support substrate 40 in the region overlapping with the IDT electrode.

[0031] When acoustic wave element 2 is an XBAR, the normalized thickness d / p of the piezoelectric film is preferably 0.5 or less, where d is the thickness (in the z-axis direction) of the piezoelectric film and p is the electrode finger pitch of the IDT electrode. By setting the normalized thickness d / p of the piezoelectric film to 0.5 or less, the relative bandwidth of the XBAR can be increased, and a resonator with a high electromechanical coupling coefficient can be formed.

[0032] It is more desirable to set the normalized thickness d / p of the piezoelectric film to 0.24 or less, which allows the fractional bandwidth of the XBAR to be 7% or more.

[0033] It is desirable that the electrode finger duty D of the IDT electrode and the normalized film thickness d / p satisfy the relationship of Equation 1.

[0034] D≦1.75(d / p)+0.075 (Formula 1)

[0035] This effectively reduces the spurious response of the higher-order mode of the XBAR. Specifically, the fractional bandwidth of the XBAR (the value obtained by dividing the difference frequency between the antiresonance frequency and the resonant frequency by the average frequency of the antiresonance frequency and the resonant frequency) can be set to 17% or less, thereby preventing the spurious response of the higher-order mode from being included in the passband.

[0036] It is more desirable that the electrode finger duty D of the IDT electrode and the normalized film thickness d / p satisfy the relationship of Equation 2.

[0037] D≦1.75(d / p)+0.05 (Formula 2)

[0038] This ensures that the fractional bandwidth of the XBAR is 17% or less, and prevents spurious signals of higher modes from being included in the passband.

[0039] Furthermore, it is desirable that the piezoelectric film is made of lithium niobate or lithium tantalate, and that the Euler angles (θ1, θ2, θ3) of the lithium niobate or lithium tantalate constituting the piezoelectric film are within the range of the following formula 3, formula 4, formula 5 or formula 6.

[0040] −10°≦θ1≦10°, and 0°≦θ2≦20° (Equation 3)

[0041] -10°≦θ1≦10°, and 20°≦θ2≦80°, and 0°≦θ3≦60° (1-(θ2-50) ２ / 900) １／２ ) (Formula 4)

[0042] -10°≦θ1≦10°, and 20°≦θ2≦80°, and [180°-60°(1-(θ2-50) ２ / 900) １／２ )]≦θ3≦180° (Formula 5)

[0043] -10°≦θ1≦10°, and [180°-30°(1-(θ3-90) ２ / 8100) １／２ )]≦θ2≦180° (Formula 6)

[0044] By defining the Euler angles of the piezoelectric film made of lithium niobate or lithium tantalate as described above, the fractional bandwidth of the XBAR can be made 5% or more.

[0045] In the acoustic wave element 2 made of XBAR, an energy trapping layer including a low acoustic impedance layer and a high acoustic impedance layer may be disposed instead of a cavity. Specifically, an energy trapping layer having a configuration in which low acoustic impedance layers with relatively low acoustic impedance and high acoustic impedance layers with relatively high acoustic impedance are alternately stacked may be disposed between the piezoelectric film and the support substrate 40. The energy trapping layer may have a laminated structure of a low acoustic speed film and a high acoustic speed film. The low acoustic speed film is a film in which the acoustic velocity of the bulk wave in the low acoustic speed film is slower than the acoustic velocity of the bulk acoustic wave propagating through the piezoelectric film. The high acoustic speed film is a film in which the acoustic velocity of the bulk wave in the high acoustic speed film is faster than the acoustic velocity of the acoustic wave propagating through the piezoelectric film.

[0046] The electrode finger pitch p is half the wavelength λ, and is defined as (W+G) where W is the line width of the electrode fingers constituting a pair of interdigital electrodes constituting the IDT electrode, and G is the space width between adjacent electrode fingers. The wavelength λ is defined by the repetition period of the multiple electrode fingers included in one of the pair of interdigital electrodes constituting the IDT electrode. The electrode finger duty D of the IDT electrode is the line width occupancy rate of the electrode fingers, which is the ratio of the line width to the sum of the line width W and the space width G, and is defined as W / (W+G). If the spacing between adjacent electrode fingers in the IDT electrode is not constant, the electrode finger pitch p of the IDT electrode is defined as the average electrode finger pitch p of the IDT electrode. ＡＶＥ The average electrode finger pitch of the IDT electrode is defined as p ＡＶＥ is defined as Di / (Ni-1), where Ni is the total number of electrode fingers included in the IDT electrode, and Di is the center-to-center distance between the electrode finger located at one end and the electrode finger located at the other end in the acoustic wave propagation direction of the IDT electrode. In addition, if the electrode finger duty D of the IDT electrode is not constant, the electrode finger duty D of the IDT electrode is calculated by multiplying the average electrode finger duty D of the IDT electrode by the following formula: ＡＶＥ The average electrode finger duty of the IDT electrode is defined as D ＡＶＥ The total number of electrode fingers included in the IDT electrode is Ni, and the total line width obtained by adding the line width W of (Ni-1) electrode fingers is W ＡＬＬ The total space width obtained by adding up the (Ni-1) space widths G included in the IDT electrode is G ＡＬＬ In this case, W ＡＬＬ / (W ＡＬＬ +G ＡＬＬ ) is defined as

[0047] The electrode finger pitch p of the comb-shaped electrodes of the IDT electrode can be measured by using a scanning electron microscope (SEM), a scanning transmission electron microscope (STEM), or a transmission electron microscope (TEM) to view the main surface of the substrate or piezoelectric film on which the comb-shaped electrodes of the IDT electrode are formed in a plan view and / or a cross-section perpendicular to the extension direction of the electrode fingers, and measuring the line width W and space width G.

[0048] The electronic device disposed on the main surface 10b side is not particularly limited, and may be, for example, a semiconductor device including a semiconductor element instead of the acoustic wave element 2. The configuration for electrically connecting the electronic device and the planar electrode 20 is not limited to the electrodes 21, 61, and 62.

[0049] According to the above-described configuration of the electronic device 1, the adhesion layer 31 has an amorphous structure. Therefore, compared to a configuration in which the adhesion layer has a crystalline structure, (1) a larger surface area can be secured for the bonding interface between the adhesion layer 31 and the planar electrode 20, and (2) the bonding interface is more easily deformed when the planar electrode 20 and the adhesion layer 31 are pressure-bonded, thereby increasing the bonding strength between the planar electrode 20 and the adhesion layer 31. Furthermore, although the adhesion layer 31 and the metal layer 32 are made of different metal materials, both have an amorphous structure, which increases the bonding strength between the adhesion layer 31 and the metal layer 32. Furthermore, because the metal layer 32 has an amorphous structure, it increases the bonding strength between the metal layer 32 and the external electrode bonded to the metal layer 32. In other words, an electronic device 1 can be provided in which the bonding quality between the planar electrode 20, the adhesion layer 31, and the metal layer 32 is high, even when the metal layer 32 bonded to the external electrode has a different composition from that of the planar electrode 20.

[0050] In this embodiment, for example, copper (Cu), a first metal material that is easy to form a through electrode in the substrate 10, is used for the via conductor 11, the planar electrode 20, and the adhesion layer 31, and nickel (Ni), a second metal material that can suppress defects such as solder erosion when soldering to an external electrode, is used for the metal layer 32, and the adhesion layer 31 and the metal layer 32 are made to have an amorphous structure, thereby improving the bonding quality of the electronic device 1.

[0051] In addition, in this embodiment, for example, copper (Cu), which is a first metal material that is easy to form a through electrode in the substrate 10, is used for the via conductor 11, the planar electrode 20, and the adhesion layer 31, a metal that can be vapor-deposited on the surface of the adhesion layer 31 is used as the second metal material for the metal layer 32, and the adhesion layer 31 and the metal layer 32 are made to have an amorphous structure, thereby improving the bonding quality of the electronic device 1.

[0052] In the electronic device 1 according to the present embodiment, a bonding layer may be further disposed on the metal layer 32. The bonding layer is made of a third metal material different from the first metal material constituting the adhesion layer 31 and the second metal material constituting the metal layer 32, has an amorphous structure, and is bonded to the metal layer 32. That is, the planar electrode 20, the adhesion layer 31, the metal layer 32, and the bonding layer are disposed in this order from the main surface 10a. In this configuration, the first metal material is, for example, copper (Cu), the second metal material is, for example, nickel (Ni), titanium (Ti), or palladium (Pd), and the third metal material is, for example, gold (Au). In this case, copper (Cu), a first metal material that is easy to form via conductors, is used for the via conductors 11, the planar electrode 20, and the adhesion layer 31; nickel (Ni), titanium (Ti), or palladium (Pd), a second metal material that can prevent the diffusion of copper (Cu) in the adhesion layer 31, is used for the metal layer 32; gold (Au), a third metal material that can form gold (Au)-gold (Au) bonds with the external electrode, is used for the bonding layer; and the adhesion layer 31, the metal layer 32, and the bonding layer are made amorphous, thereby improving the bonding quality of the electronic device 1.

[0053] The metal layer 32 may be made up of multiple layers made of a metal material different from the first metal material.

[0054] [2 Structure of Transfer Sheet 30] Next, the structure of the transfer sheet 30 used when forming the adhesive layer 31 and the metal layer 32 as electrodes of the electronic device 1 will be described.

[0055] 2 is a cross-sectional view of a transfer sheet 30 according to an embodiment. The figure shows the cross-sectional structure of the transfer sheet 30 used when forming an adhesive layer 31 and a metal layer 32 as electrodes of an electronic device 1. The transfer sheet 30 includes an adhesive layer 31p, a metal layer 32p, a release layer 33, and a resin film 35.

[0056] The adhesion layer 31p is made of a first metal material, extends along the plane (xy plane) of the release layer 33, and has an amorphous structure. The adhesion layer 31p is made of, for example, copper (Cu) and has a thickness of, for example, 100 nm. The adhesion layer 31p may be a metal layer of a single element, or an alloy layer made of multiple elements. In other words, the first metal material includes a single element material or a material made of multiple elements.

[0057] The metal layer 32p is made of a second metal material different from the first metal material, extends along the plane (xy plane) of the release layer 33, and has an amorphous structure. The metal layer 32p is bonded to the adhesion layer 31p and is made of, for example, nickel (Ni), with a thickness of, for example, 50 nm. The metal layer 32p may be a single-element metal layer or an alloy layer made of multiple elements. In other words, the second metal material includes a single-element material or a material made of multiple elements. When the metal layer 32p and the adhesion layer 31p are made of the same combination of multiple elements, the composition ratio of the multiple elements making up the metal layer 32p is different from the composition ratio of the multiple elements making up the adhesion layer 31p.

[0058] The release layer 33 is made mainly of silicone rubber or acrylic resin, extends along the xy plane, and is bonded to the metal layer 32p. The release layer 33 has a thickness of, for example, several μm to several tens of μm.

[0059] The resin film 35 extends along the xy plane and is bonded to the release layer 33. The resin film 35 has a thickness of, for example, 16 to 50 μm. The resin film 35 is made of, for example, PET (Polyethyleneterephthalate). The adhesive layer 31p, the metal layer 32p, the release layer 33, and the resin film 35 are bonded in this order. Note that the transfer sheet 30 does not necessarily have to include the resin film 35.

[0060] In the manufacturing process of the electronic device 1, the transfer sheet 30 is brought into contact with the planar electrode 20 with the adhesive layer 31p of the transfer sheet 30 facing the main surface 10a of a precursor 1P (shown in FIGS. 6A and 6B ) of the electronic device 1, and the adhesive layer 31 and the metal layer 32 are transferred to the planar electrode 20. The precursor 1P of the electronic device 1 is an electronic device having an acoustic wave element 2 disposed on the main surface 10b of the substrate 10, a planar electrode 20 disposed on the main surface 10a of the substrate 10, and the adhesive layer 31 and the metal layer 32 not disposed on the planar electrode 20.

[0061] In the step of bringing the transfer sheet 30 into contact with the planar electrode 20, the adhesive layer 31 and the metal layer 32 are transferred onto the planar electrode 20. That is, the portions of the adhesive layer 31p and the metal layer 32p that are in contact with the planar electrode 20 are bonded to the planar electrode 20, and the other portions of the adhesive layer 31p and the metal layer 32p that are not in contact with the planar electrode 20 remain on the transfer sheet 30.

[0062] In the manufacture of conventional electronic devices, transfer sheets are used in which the adhesion layer and metal layer have a crystalline structure. In this case, the degree of bonding between the particles of the adhesion layer and metal layer in a direction parallel to the plane of the transfer sheet is high due to the crystalline structure. Therefore, in the process of contacting the transfer sheet with the planar electrode 20, it is not possible to accurately separate the adhesion layer and metal layer that contact the planar electrode 20 from the adhesion layer and metal layer that do not contact the planar electrode 20. As a result, the portions of the adhesion layer and metal layer of the transfer sheet that contact the planar electrode 20 are bonded to the planar electrode 20, but the remaining portions of the adhesion layer and metal layer of the transfer sheet that do not contact the planar electrode 20 remain on the main surface 10a.

[0063] In contrast, in the transfer sheet 30 according to the present embodiment, the adhesion layer 31p and the metal layer 32p have an amorphous structure, and therefore, compared to a configuration in which the adhesion layer and the metal layer have a crystalline structure, the degree of bonding between the particles of the adhesion layer 31p and the metal layer 32p in the direction parallel to the plane of the transfer sheet 30 is low due to the amorphous structure. Therefore, the adhesion layer 31p and the metal layer 32p in contact with the planar electrode 20 can be separated with high precision from the adhesion layer 31p and the metal layer 32p that are not in contact with the planar electrode 20.

[0064] As a result, the portions of the adhesion layer 31p and the metal layer 32p that come into contact with the planar electrode 20 are bonded to the planar electrode 20, and the adhesion layer 31p and the metal layer 32p are not bonded to the main surface 10a where the planar electrode 20 is not disposed. In other words, by using the transfer sheet 30 according to this embodiment, the transfer accuracy of the adhesion layer 31 and the metal layer 32 to the precursor 1P of the electronic device 1 is improved. Furthermore, the adhesion layer 31p and the metal layer 32p that constitute the transfer sheet 30 have the same metallic material and the same amorphous structure as the adhesion layer 31 and the metal layer 32 that are transferred to the planar electrode 20, and do not contain impurities such as solvents. Therefore, the density of the adhesion layer 31 and the metal layer 32 due to the amorphous structure is ensured, and the bonding quality with the planar electrode 20 and the external electrode is improved.

[0065] 3 is a cross-sectional view of an electronic device 1A according to a first modification of the embodiment. As shown in the figure, the electronic device 1A includes a substrate 10, a planar electrode 20, an adhesion layer 31A, a metal layer 32A, a via conductor 11, an acoustic wave element 2, and electrodes 21, 61, and 62. The electronic device 1A according to this modification differs from the electronic device 1 according to the embodiment in the structures of the adhesion layer 31A and the metal layer 32A. Hereinafter, the electronic device 1A according to this modification will be described focusing on the different configurations, and a description of the same configurations as those of the electronic device 1 according to the embodiment will be omitted.

[0066] The planar electrode 20 is a conductive electrode layer that extends along the main surface 10a (xy plane) and is disposed on the main surface 10a. The planar electrode 20 is made of the same first metal material as the via conductors 11, such as copper (Cu).

[0067] The adhesion layer 31A is made of the same first metal material as the planar electrode 20 and has an amorphous structure. The adhesion layer 31A is bonded to the planar electrode 20 and is made of, for example, copper (Cu). The adhesion layer 31A may be a single-element metal layer or an alloy layer made of multiple elements. In other words, the first metal material includes a single-element material or a material composed of multiple elements. When the planar electrode 20 and the adhesion layer 31A are made of the same combination of elements, the composition ratio of the multiple elements making up the planar electrode 20 is the same as the composition ratio of the multiple elements making up the adhesion layer 31A.

[0068] The metal layer 32A is made of a second metal material different from the first metal material and has an amorphous structure. The metal layer 32A is bonded to the adhesion layer 31A and is made of, for example, nickel (Ni). The metal layer 32A may be a single-element metal or an alloy made of multiple elements. In other words, the second metal material includes a single-element material or a material made of multiple elements. When the metal layer 32A and the adhesion layer 31A are made of the same combination of multiple elements, the composition ratio of the multiple elements making up the metal layer 32A is different from the composition ratio of the multiple elements making up the adhesion layer 31A.

[0069] The planar electrode 20, the adhesive layer 31A, and the metal layer 32A are arranged in this order from the main surface 10a.

[0070] The adhesion layer 31A and the metal layer 32A have a groove structure with a depth direction that is perpendicular to the main surface 10a (z-axis direction). Specifically, grooves 34 are formed in the adhesion layer 31A and the metal layer 32A. Of the two pairs of adhesion layers 31A and metal layers 32A shown in Figure 3, one pair of adhesion layers 31A and metal layers 32A (the adhesion layer 31A and metal layer 32A on the left side in Figure 3) has multiple grooves 34 formed along a direction parallel to the main surface 10a (x-axis direction).

[0071] 4 is a cross-sectional view of a transfer sheet 30A according to a first modified example of the embodiment. The cross-sectional structure of the transfer sheet 30A is shown, which is used when forming an adhesive layer 31A and a metal layer 32A as electrodes of an electronic device 1A. The transfer sheet 30A includes an adhesive layer 31r, a metal layer 32r, a release layer 33, and a resin film 35.

[0072] The adhesion layer 31r is made of a first metal material, extends along the plane (xy plane) of the release layer 33, and has an amorphous structure. The adhesion layer 31r is made of, for example, copper (Cu) and has a thickness of, for example, 100 nm. The adhesion layer 31r may be a metal layer of a single element, or an alloy layer made of multiple elements. In other words, the first metal material includes a single element material or a material made of multiple elements.

[0073] The metal layer 32r is made of a second metal material different from the first metal material, extends along the plane (xy plane) of the release layer 33, and has an amorphous structure. The metal layer 32r is bonded to the adhesion layer 31r and is made of, for example, nickel (Ni). The metal layer 32r may be a single-element metal layer or an alloy layer made of multiple elements. That is, the second metal material includes a single-element material or a material composed of multiple elements. When the metal layer 32r and the adhesion layer 31r are made of the same combination of multiple elements, the composition ratio of the multiple elements making up the metal layer 32r is different from the composition ratio of the multiple elements making up the adhesion layer 31r.

[0074] The release layer 33 is made primarily of silicone rubber or acrylic resin, extends along a plane (xy plane), and is bonded to the metal layer 32r. The release layer 33 has a thickness of, for example, several μm to several tens of μm. The adhesion layer 31r, metal layer 32r, and release layer 33 are bonded in this order.

[0075] The resin film 35 extends along the xy plane and is bonded to the release layer 33. The resin film 35 has a thickness of, for example, 16 to 50 μm. The resin film 35 is made of, for example, PET. The adhesive layer 31r, the metal layer 32r, the release layer 33, and the resin film 35 are bonded in this order. Note that the transfer sheet 30A does not necessarily have to include the resin film 35.

[0076] The metal layer 32r and the adhesive layer 31r have a groove structure with a depth direction that is perpendicular to the plane of the transfer sheet 30A (z-axis direction). Specifically, the adhesive layer 31r and the metal layer 32r have a plurality of grooves 34 formed along a direction that is parallel to the plane of the transfer sheet 30A (x-axis direction).

[0077] 5A is a plan view of a transfer sheet 30A according to a first modification of the embodiment. Specifically, this figure is a plan view of the adhesive layer 31r of the transfer sheet 30A, and is a cross-sectional view taken along line IV-IV in FIG. 4. The dashed lines in this figure represent a plurality of intermittently formed grooves 34, which form a so-called perforated mesh. In the transfer sheet 30A according to this modification, the unit area of ​​the adhesive layer 31r surrounded by the plurality of grooves 34 is hexagonal. The plurality of grooves 34 do not have to be formed intermittently, and may form a mesh shape in which the grooves 34 are continuously formed.

[0078] In the manufacturing process of the electronic device 1A, the transfer sheet 30A is bonded to the planar electrode 20 with the adhesion layer 31r of the transfer sheet 30A facing the main surface 10a of the precursor 1P of the electronic device 1A, and the adhesion layer 31A and the metal layer 32A are transferred to the planar electrode 20. The precursor 1P of the electronic device 1A is an electronic device having an acoustic wave element 2 arranged on the main surface 10b of the substrate 10, a planar electrode 20 arranged on the main surface 10a of the substrate 10, and no adhesion layer 31A or metal layer 32A arranged on the planar electrode 20.

[0079] In the process of joining the transfer sheet 30A and the flat electrode 20, the portions of the adhesive layer 31r and the metal layer 32r that are in contact with the flat electrode 20 are joined to the flat electrode 20, and the portions of the adhesive layer 31r and the metal layer 32r that are not in contact with the flat electrode 20 remain on the transfer sheet 30A.

[0080] Because the adhesion layer 31r and the metal layer 32r have an amorphous structure, the degree of interparticle bonding in the adhesion layer 31r and the metal layer 32r in a direction parallel to the plane of the transfer sheet 30A is lower due to the amorphous structure, compared to a configuration in which the adhesion layer and the metal layer have a crystalline structure. This allows the adhesion layer 31r and the metal layer 32r in contact with the planar electrode 20 to be separated with high precision from the adhesion layer 31r and the metal layer 32r not in contact with the planar electrode 20. Furthermore, because the transfer sheet 30A has multiple grooves 34, it is possible to separate the portions of the adhesion layer 31r and the metal layer 32r in contact with the planar electrode 20 from the other portions of the adhesion layer 31r and the metal layer 32r not in contact with the planar electrode 20 using the grooves 34 as boundaries. As a result, the portions of the adhesion layer 31r and the metal layer 32r that are in contact with the planar electrode 20 are bonded to the planar electrode 20, and the adhesion layer 31r and the metal layer 32r are not bonded to the main surface 10a where the planar electrode 20 is not disposed. In other words, by using the transfer sheet 30A according to this modification, the transfer accuracy of the adhesion layer 31A and the metal layer 32A onto the precursor 1P of the electronic device 1A is improved.

[0081] The maximum diameter D of the unit area of ​​the adhesion layer 31r surrounded by the plurality of grooves 34 is smaller than the minimum diameter in a direction parallel to the main surface 10a (xy plane) of the planar electrode 20 of the electronic device 1A.

[0082] As a result, the maximum diameter D of a unit area of ​​the adhesion layer 31r surrounded by multiple grooves 34 is smaller than the minimum diameter in a direction parallel to the main surface 10a of the planar electrode 20, so it is possible to separate with high precision the portion of the adhesion layer 31r and the metal layer 32r that is in contact with the planar electrode 20 from the other portion of the adhesion layer 31r and the metal layer 32r that is not in contact with the planar electrode 20, using the grooves 34 as a boundary.

[0083] The plurality of grooves 34 do not have to be formed in both the adhesive layer 31r and the metal layer 32r, and may be formed in only one of the adhesive layer 31r and the metal layer 32r.

[0084] Furthermore, the unit area of ​​the adhesive layer 31r surrounded by the plurality of grooves 34 is not limited to being hexagonal when the transfer sheet 30A is viewed in plan.

[0085] 5B is a plan view of a transfer sheet 30B according to a second modification of the embodiment. Specifically, this figure is a plan view of the adhesive layer 31s of the transfer sheet 30B. The dashed lines in this figure represent a plurality of intermittently formed grooves 34, and the plurality of grooves 34 have a so-called perforated mesh shape. In the transfer sheet 30B according to this modification, the unit area of ​​the adhesive layer 31s surrounded by the plurality of grooves 34 is rectangular. The plurality of grooves 34 do not have to be formed intermittently, and may have a mesh shape in which the grooves 34 are continuously formed.

[0086] The transfer sheet 30B includes an adhesive layer 31s, a metal layer 32s (not shown in FIG. 5B), and a release layer 33 (not shown in FIG. 5B).

[0087] The adhesion layer 31s is made of a first metal material and has an amorphous structure. The metal layer 32s is made of a second metal material different from the first metal material and has an amorphous structure. The metal layer 32s is bonded to the adhesion layer 31s. The release layer 33 is bonded to the metal layer 32s. The adhesion layer 31s, the metal layer 32s, and the release layer 33 are bonded in this order.

[0088] Here, the maximum diameter D of the unit area of ​​the adhesion layer 31s surrounded by the plurality of grooves 34 is smaller than the minimum diameter in the direction parallel to the main surface 10a of the flat electrode 20 of the electronic device 1A.

[0089] This makes it possible to separate with higher precision, at the grooves 34, the portions of the adhesion layer 31s and the metal layer 32s that are in contact with the planar electrode 20 from the other portions of the adhesion layer 31s and the metal layer 32s that are not in contact with the planar electrode 20. Therefore, by using the transfer sheet 30B having the above-described groove structure, the transfer precision of the adhesion layer 31A and the metal layer 32A onto the precursor 1P of the electronic device 1A is further improved.

[0090] FIG. 5C is a plan view of a transfer sheet 30C according to a third modification of the embodiment. Specifically, this figure is a plan view of the adhesive layer 31t of the transfer sheet 30C. The dashed lines in this figure represent a plurality of intermittently formed grooves 34, and the plurality of grooves 34 form a so-called perforated mesh. In the transfer sheet 30C according to this modification, the unit area of ​​the adhesive layer 31t surrounded by the plurality of grooves 34 is a rectangle (diamond). The plurality of grooves 34 do not have to be formed intermittently, and may be a mesh shape in which the grooves 34 are continuously formed. Furthermore, the unit area does not have to be a rectangle (diamond), but may be a polygon or a circle.

[0091] The transfer sheet 30C includes an adhesive layer 31t, a metal layer 32t (not shown in FIG. 5C), and a release layer 33 (not shown in FIG. 5C).

[0092] The adhesion layer 31t is made of a first metal material and has an amorphous structure. The metal layer 32t is made of a second metal material different from the first metal material and has an amorphous structure. The metal layer 32t is bonded to the adhesion layer 31t. The release layer 33 is bonded to the metal layer 32t. The adhesion layer 31t, the metal layer 32t, and the release layer 33 are bonded in this order.

[0093] Here, the maximum diameter D of the unit area of ​​the adhesion layer 31t surrounded by the plurality of grooves 34 is smaller than the minimum diameter in the direction parallel to the main surface 10a of the flat electrode 20 of the electronic device 1A.

[0094] This makes it possible to separate with higher precision, at the grooves 34, the portions of the adhesion layer 31t and the metal layer 32t that are in contact with the planar electrode 20 from the other portions of the adhesion layer 31t and the metal layer 32t that are not in contact with the planar electrode 20. Therefore, by using the transfer sheet 30C having the above-described groove structure, the transfer precision of the adhesion layer 31A and the metal layer 32A onto the precursor 1P of the electronic device 1A is further improved.

[0095] [4. Method for Manufacturing Electronic Device 1] Next, a method for manufacturing the electronic device 1 according to this embodiment will be described.

[0096] 6A is a diagram illustrating a first step (S10) of the method for manufacturing electronic device 1 according to the embodiment. First, as shown in FIG. 6A , a plurality of planar electrodes 20 electrically connected to acoustic wave elements 2 are formed on main surface 10a of substrate 10 (S10). Also, transfer sheet 30 is prepared, which has a configuration in which adhesive layer 31p, metal layer 32p, release layer 33, and resin film 35 are bonded in this order.

[0097] 6B is a diagram illustrating a second step (S20) of the manufacturing method for the electronic device 1 according to the embodiment. After step S10, the transfer sheet 30 is brought into contact with the plurality of planar electrodes 20 of the precursor 1P with the adhesive layer 31p facing the main surface 10a (S20). In step S20, the transfer sheet 30 may be pressed against the plurality of planar electrodes 20 to bring them into contact. This improves the degree of adhesion between the planar electrodes 20 and the adhesive layer 31p. Furthermore, in step S20, the transfer sheet 30 may be heated. This further improves the degree of adhesion between the planar electrodes 20 and the adhesive layer 31p.

[0098] 6C is a diagram showing a third step (S30) of the manufacturing method of the electronic device 1 according to the embodiment. After step S20, the transfer sheet 30p is separated from the electronic device 1, and the adhesive layer 31 and the metal layer 32 are transferred to the plurality of planar electrodes 20 (S30). Note that the transfer sheet 30p is obtained by transferring and removing a portion of the adhesive layer 31p and the metal layer 32p of the transfer sheet 30 to the planar electrodes 20.

[0099] In other words, the manufacturing method of the electronic device 1 according to this embodiment involves forming a plurality of planar electrodes 20 on the main surface 10a of the substrate 10 (S10), bringing the transfer sheet 30 into contact with the plurality of planar electrodes 20 with the adhesive layer 31p facing the main surface 10a (S20), and transferring the adhesive layer 31 and the metal layer 32 to the plurality of planar electrodes 20 (S30).

[0100] According to this, the adhesion layer 31p and the metal layer 32p have an amorphous structure, and therefore the degree of bonding between the particles of the adhesion layer 31p and the metal layer 32p in a direction parallel to the plane of the transfer sheet 30 is lower than in a configuration in which the adhesion layer and the metal layer have a crystalline structure. Furthermore, when the adhesion layer 31p and the metal layer 32p are bonded to the planar electrode 20, the amorphous structure of the adhesion layer 31p makes the bonding interface more easily deformed, thereby increasing the bonding strength between the planar electrode 20 and the adhesion layer 31p. Therefore, the adhesion layer 31p and the metal layer 32p in contact with the planar electrode 20 are separated with high precision from the adhesion layer 31p and the metal layer 32p that are not in contact with the planar electrode 20. As a result, the portions of the adhesion layer 31p and the metal layer 32p in contact with the planar electrode 20 are bonded to the planar electrode 20, and the adhesion layer 31p and the metal layer 32p are not bonded to the main surface 10a where the planar electrode 20 is not disposed. In other words, by using the transfer sheet 30 according to this embodiment, the accuracy of transferring the adhesive layer 31 and the metal layer 32 onto the planar electrode 20 is improved.

[0101] Furthermore, since the metal layer 32p has an amorphous structure, it is possible to increase the bonding strength between the transferred metal layer 32 and the external electrode. In other words, it is possible to provide an electronic device 1 having high bonding quality between the planar electrode 20, the adhesion layer 31, and the metal layer 32 while changing the composition of the metal layer 32 bonded to the external electrode to a different composition from that of the planar electrode 20.

[0102] In steps S20 and S30, the adhesive layer 31p of the transfer sheet 30 may be brought into contact with a plurality of planar electrodes 20 at the same time, so that the adhesive layer 31 and the metal layer 32 are transferred to the plurality of planar electrodes 20 at the same time.

[0103] This simplifies the manufacturing process because the adhesive layer 31 and metal layer 32 can be transferred to many planar electrodes 20 simultaneously, compared to conventional manufacturing methods for electronic devices in which a conductive film formed from conductive ink applied to a plate cylinder is brought into contact with the plate cylinder and the conductive film is transferred to a wiring pattern.

[0104] The manufacturing method of the electronic device 1 according to the present embodiment described above can also be applied to the manufacturing method of the electronic device 1A according to Modification 1. That is, in the manufacturing method of the electronic device 1A according to Modification 1, a plurality of planar electrodes 20 are formed on the main surface 10a of the substrate 10 (S10), a transfer sheet 30A is brought into contact with the plurality of planar electrodes 20 with the adhesion layer 31r facing the main surface 10a (S20), and the adhesion layer 31A and the metal layer 32A are transferred to the plurality of planar electrodes 20 (S30).

[0105] Here, multiple grooves 34 are formed in at least one of the adhesive layer 31r and the metal layer 32r of the transfer sheet 30A, and when the transfer sheet 30A is viewed in a plane, the multiple grooves 34 have a mesh shape, and the maximum diameter D of the unit area surrounded by the multiple grooves 34 is smaller than the minimum diameter in a direction parallel to each of the main surfaces 10a of the multiple planar electrodes 20.

[0106] In this configuration, the adhesion layer 31r and the metal layer 32r have an amorphous structure, and therefore the degree of inter-particle bonding in the adhesion layer 31r and the metal layer 32r in the direction parallel to the plane of the transfer sheet 30A is lower than in a configuration in which the adhesion layer and the metal layer have a crystalline structure. Furthermore, when the adhesion layer 31r and the metal layer 32r are bonded to the planar electrode 20, the bonding interface of the adhesion layer 31r is easily deformed, which increases the bonding strength between the planar electrode 20 and the adhesion layer 31r. Therefore, the adhesion layer 31r and the metal layer 32r in contact with the planar electrode 20 can be separated with high precision from the adhesion layer 31r and the metal layer 32r that are not in contact with the planar electrode 20.

[0107] Furthermore, because the maximum diameter D of a unit area of ​​the adhesion layer 31r surrounded by the multiple grooves 34 is smaller than the minimum diameter in a direction parallel to the main surface 10a of the planar electrode 20, it is possible to separate with high precision, using the multiple grooves 34 as boundaries, the portions of the adhesion layer 31r and metal layer 32r in contact with the planar electrode 20 from the other portions of the adhesion layer 31r and metal layer 32r that are not in contact with the planar electrode 20. This improves the transfer accuracy of the adhesion layer 31A and metal layer 32A to the planar electrode 20. Furthermore, because the metal layer 32r has an amorphous structure, it is possible to increase the bonding strength between the transferred metal layer 32A and the external electrode. In other words, it is possible to provide an electronic device 1A that has high bonding quality between the planar electrode 20, the adhesion layer 31A, and the metal layer 32A while changing the composition of the metal layer 32A bonded to the external electrode to a different composition from that of the planar electrode 20.

[0108] [5. Effects, etc.] As described above, the electronic device 1 according to this embodiment includes a substrate 10 having principal surfaces 10a and 10b facing each other, an electronic device disposed on the substrate 10, a planar electrode 20 electrically connected to the electronic device and disposed on the principal surface 10a, an adhesion layer 31 made of the same first metal material as the planar electrode 20 and having an amorphous structure, and a metal layer 32 made of a second metal material different from the first metal material and having an amorphous structure, with the planar electrode 20, adhesion layer 31, and metal layer 32 arranged in this order from the principal surface 10a.

[0109] According to this, since the adhesion layer 31 has an amorphous structure, a large surface area can be ensured at the bonding interface between the adhesion layer 31 and the planar electrode 20. Furthermore, since the bonding interface is easily deformed when the planar electrode 20 and the adhesion layer 31 are bonded, the bonding strength between the planar electrode 20 and the adhesion layer 31 can be increased. Although the adhesion layer 31 and the metal layer 32 are made of different metal materials, both have an amorphous structure, which increases the bonding strength between the adhesion layer 31 and the metal layer 32. Furthermore, since the metal layer 32 has an amorphous structure, it increases the bonding strength between the metal layer 32 and the external electrode bonded to the metal layer 32. In other words, an electronic device 1 can be provided in which the bonding quality between the planar electrode 20, the adhesion layer 31, and the metal layer 32 is high, while the metal layer 32 bonded to the external electrode has a different composition from that of the planar electrode 20.

[0110] Furthermore, for example, in the electronic device 1A according to the first modification, at least one of the adhesion layer 31A and the metal layer 32A has a groove structure whose depth direction is perpendicular to the main surface 10a.

[0111] In the manufacturing process of the electronic device 1A, the transfer sheet 30A is bonded to the planar electrode 20 with the adhesion layer 31r of the transfer sheet 30A facing the main surface 10a of the precursor 1P of the electronic device 1A, and the adhesion layer 31A and the metal layer 32A are transferred to the planar electrode 20. Because the adhesion layer 31r and the metal layer 32r have an amorphous structure, the adhesion layer 31r and the metal layer 32r in contact with the planar electrode 20 are separated with high precision from the adhesion layer 31r and the metal layer 32r not in contact with the planar electrode 20. Furthermore, because the transfer sheet 30A has multiple grooves 34, it is possible to separate the portions of the adhesion layer 31r and the metal layer 32r in contact with the planar electrode 20 from the other portions of the adhesion layer 31r and the metal layer 32r not in contact with the planar electrode 20, using the grooves 34 as boundaries. In other words, the transfer accuracy of the adhesion layer 31A and the metal layer 32A to the precursor 1P of the electronic device 1A is improved.

[0112] Furthermore, for example, in the electronic device 1A according to the first modification, at least one of the adhesion layer 31A and the metal layer 32A has a plurality of grooves 34 extending in a direction parallel to the main surface 10a.

[0113] This makes it possible to separate with higher precision the portion of the transfer sheet 30A that is in contact with the flat electrode 20 from the other portion of the transfer sheet 30A that is not in contact with the flat electrode 20, with the groove 34 as the boundary.

[0114] For example, in the electronic device 1, the first metal material is copper and the second metal material is nickel.

[0115] According to this, for example, copper, which is easy to form via conductors in the substrate 10, is used for the planar electrode 20 and the adhesion layer 31, nickel, which can suppress defects such as solder erosion when soldering to an external electrode, is used for the metal layer 32, and the adhesion layer 31 and the metal layer 32 are made to have an amorphous structure, thereby improving the bonding quality of the electronic device 1.

[0116] For example, the electronic device 1 further includes a bonding layer made of a third metal material different from the first metal material and the second metal material and having an amorphous structure, and the planar electrode 20, the adhesion layer 31, the metal layer 32, and the bonding layer are arranged in this order from the main surface 10a.

[0117] According to this, the layers bonded onto the planar electrode 20 are not limited to two layers, an adhesive layer and a metal layer, but may be three or more layers, thereby improving the degree of freedom in the layers bonded onto the planar electrode 20.

[0118] For example, in the electronic device 1, the first metal material is copper, the second metal material is nickel, titanium or palladium, and the third metal material is gold.

[0119] According to this, for example, copper, which is easy to form via conductors in the substrate 10, is used for the planar electrode 20 and the adhesion layer 31, nickel, titanium or palladium, which can prevent the diffusion of copper in the adhesion layer 31, is used for the metal layer 32, gold, which can be bonded to the external electrode by gold-gold bonding, is used for the bonding layer, and the adhesion layer 31, metal layer 32 and bonding layer are made to have an amorphous structure, thereby improving the bonding quality of the electronic device 1.

[0120] Furthermore, for example, in electronic apparatus 1 , the electronic device includes acoustic wave element 2 and is disposed on main surface 10 b side of substrate 10 .

[0121] This makes it possible to provide an acoustic wave device with high bonding quality of the conductive film.

[0122] Furthermore, for example, in the electronic apparatus 1, the electronic device includes a semiconductor element and is disposed on the main surface 10b side of the substrate 10.

[0123] This makes it possible to provide a semiconductor device with high-quality bonding of the conductive film.

[0124] Furthermore, the manufacturing method of the electronic device 1 according to this embodiment is a manufacturing method of the electronic device 1 including a substrate 10 and an electronic device formed on the substrate 10, and includes the steps of forming a plurality of planar electrodes 20 on the main surface 10a to be electrically connected to the electronic device, and contacting a transfer sheet 30 having a structure in which an adhesion layer 31p made of the same first metal material as the plurality of planar electrodes 20 and having an amorphous structure, a metal layer 32p made of a second metal material different from the first metal material and having an amorphous structure, and a release layer 33 are laminated in this order with the plurality of planar electrodes 20 with the adhesion layer 31p facing the main surface 10a, and transferring the adhesion layer 31 and the metal layer 32 to the plurality of planar electrodes 20.

[0125] In this configuration, the adhesion layer 31p and the metal layer 32p have an amorphous structure, which reduces the degree of interparticle bonding between the adhesion layer 31p and the metal layer 32p in a direction parallel to the plane of the transfer sheet 30 compared to a configuration in which the adhesion layer and the metal layer have a crystalline structure. Furthermore, when the adhesion layer 31p and the metal layer 32p are bonded to the planar electrode 20, the amorphous structure of the adhesion layer 31p makes the bonding interface more easily deformable, thereby increasing the bonding strength between the planar electrode 20 and the adhesion layer 31p. Therefore, the adhesion layer 31p and the metal layer 32p in contact with the planar electrode 20 are separated with high precision from the adhesion layer 31p and the metal layer 32p not in contact with the planar electrode 20. This improves the transfer accuracy of the adhesion layer 31 and the metal layer 32 to the planar electrode 20. Furthermore, the amorphous structure of the metal layer 32p allows for increased bonding strength between the transferred metal layer 32 and the external electrode. That is, the metal layer 32 bonded to the external electrode can be changed to have a different composition from that of the planar electrode 20, and the electronic device 1 can be provided with high bonding quality between the planar electrode 20, the adhesive layer 31, and the metal layer 32.

[0126] For example, in the manufacturing method of the electronic device 1, in the process of transferring the adhesion layer 31 and the metal layer 32, the adhesion layer 31p of the transfer sheet 30 is simultaneously brought into contact with multiple planar electrodes 20, thereby simultaneously transferring the adhesion layer 31 and the metal layer 32 to the multiple planar electrodes 20.

[0127] This simplifies the manufacturing process because, compared to conventional methods for manufacturing electronic devices in which a conductive film formed from conductive ink applied to a plate cylinder is brought into contact with the plate cylinder and transferred to a wiring pattern, the adhesive layer 31p and metal layer 32p can be transferred to many planar electrodes 20 simultaneously with high precision.

[0128] For example, in the manufacturing method of the electronic device 1A, a plurality of grooves 34 are formed in at least one of the adhesive layer 31r and the metal layer 32r of the transfer sheet 30A, with the depth direction being perpendicular to the plane of the transfer sheet 30A, and when the transfer sheet 30A is viewed in a plane, the plurality of grooves 34 have a mesh shape, and the maximum diameter D of the unit area surrounded by the plurality of grooves 34 is smaller than the minimum diameter in the direction parallel to each of the main surfaces 10a of the plurality of planar electrodes 20.

[0129] This makes it possible to separate with high precision, at the boundaries of the multiple grooves 34, the portions of the adhesion layer 31r and the metal layer 32r in contact with the planar electrode 20 from the other portions of the adhesion layer 31r and the metal layer 32r that are not in contact with the planar electrode 20. This improves the transfer precision of the adhesion layer 31A and the metal layer 32A onto the planar electrode 20.

[0130] Furthermore, for example, in the manufacturing method of the electronic device 1 , in the step of transferring the adhesive layer 31 and the metal layer 32 , the transfer sheet 30 is pressed onto the plurality of planar electrodes 20 .

[0131] This improves the degree of adhesion between the planar electrode 20 and the adhesion layer 31p, thereby further improving the transfer accuracy of the adhesion layer 31A and the metal layer 32A onto the planar electrode 20.

[0132] (Other Embodiments) While the electronic device according to the present invention has been described above with reference to embodiments and modifications thereof, the present invention is not limited to the above embodiments and modifications. The present invention also includes modifications obtained by applying various modifications to the above embodiments and modifications that would occur to those skilled in the art without departing from the spirit of the present invention, as well as various devices incorporating the electronic device according to the present invention.

[0133] In the film (layer) structure of the present disclosure, whether the film (layer) has an amorphous structure can be determined by electron diffraction using a scanning transmission electron microscope (STEM). The observation conditions for electron diffraction using STEM are as follows: when the thickness of the film (layer) being observed is 50 to 100 nm, the observation mode is spot electron diffraction, the electron beam spot diameter is 3 nmφ+α, the electron beam irradiation angle is approximately 2.5 mrad, and the acceleration voltage is 200 kV.

[0134] Figure 7A shows an example of an electron diffraction pattern of an amorphous film observed with an STEM. Figure 7B shows an example of an electron diffraction pattern of a single-crystal film (Si) observed with an STEM. In Figures 7A and 7B, bright spots in the diffraction patterns are highlighted with black dots.

[0135] As shown in Fig. 7A, the electron diffraction pattern of an amorphous film is a so-called halo pattern in which one diffraction spot has a halo ring, whereas as shown in Fig. 7B, the electron diffraction pattern of a single crystalline film is a geometric pattern in which diffracted electrons corresponding to the crystal orientation, interplanar spacing, etc. form multiple diffraction spots.

[0136] The size of the diffraction spots and the size and shading of the halo ring in the electron diffraction pattern of an amorphous film are not limited to those in the diffraction pattern shown in Fig. 7A. Furthermore, the number and geometrical pattern of multiple diffraction spots in the electron diffraction pattern of a single crystalline film are not limited to those in the diffraction pattern shown in Fig. 7B.

[0137] In the electronic device 1 according to the embodiment, if the electron diffraction pattern at the end (side portion) of each of the adhesion layer 31 and the metal layer 32 in the film surface direction is the electron diffraction pattern as shown in Figure 7A, the adhesion layer 31 and the metal layer 32 are determined to have an amorphous structure.

[0138] Furthermore, in the electronic device 1A relating to variant example 1, if the electron diffraction pattern near the groove 34 in each of the adhesion layer 31A and the metal layer 32A is the electron diffraction pattern as shown in Figure 7A, the adhesion layer 31A and the metal layer 32A are determined to have an amorphous structure.

[0139] The features of the electronic device and the method for manufacturing the electronic device described based on the above embodiment will be described below.

[0140] <1> An electronic device comprising: a substrate having a first main surface and a second main surface opposing each other; an electronic device disposed on the substrate; a planar electrode electrically connected to the electronic device and disposed on the first main surface; an adhesion layer made of the same first metal material as the planar electrode and having an amorphous structure; and a metal layer made of a second metal material different from the first metal material and having an amorphous structure, wherein the planar electrode, the adhesion layer, and the metal layer are disposed in this order from the first main surface.

[0141] <2> The electronic device according to <1>, wherein at least one of the adhesion layer and the metal layer has a groove structure whose depth direction is perpendicular to the first main surface.

[0142] <3> The electronic device according to <2>, wherein at least one of the adhesion layer and the metal layer has a plurality of grooves extending in a direction parallel to the first main surface.

[0143] <4> The electronic device according to any one of <1> to <3>, wherein the first metal material is copper, and the second metal material is nickel.

[0144] <5> The electronic device according to any one of <1> to <4>, further comprising: a bonding layer made of a third metal material different from the first metal material and the second metal material and having an amorphous structure, wherein the planar electrode, the adhesion layer, the metal layer, and the bonding layer are arranged in this order from the first main surface.

[0145] <6> The electronic device according to <5>, wherein the first metal material is copper, the second metal material is nickel, titanium, or palladium, and the third metal material is gold.

[0146] <7> The electronic apparatus according to any one of <1> to <6>, wherein the electronic device includes an acoustic wave element and is disposed on the second main surface side of the substrate.

[0147] <8> The electronic apparatus according to any one of <1> to <6>, wherein the electronic device includes a semiconductor element and is disposed on the second main surface side of the substrate.

[0148] <9> A method for manufacturing an electronic device including a substrate and an electronic device formed on the substrate, the method comprising: forming, on a main surface of the substrate, a plurality of planar electrodes electrically connected to the electronic device; and contacting a transfer sheet having a structure in which an adhesion layer made of the same first metal material as the plurality of planar electrodes and having an amorphous structure, a metal layer made of a second metal material different from the first metal material and having an amorphous structure, and a release layer are laminated in this order with the plurality of planar electrodes with the adhesion layer facing the main surface, to transfer the adhesion layer and the metal layer to the plurality of planar electrodes.

[0149] <10> The method for manufacturing an electronic device according to <9>, wherein in the step of transferring the adhesion layer and the metal layer, the adhesion layer of the transfer sheet is brought into contact with the plurality of planar electrodes simultaneously, thereby simultaneously transferring the adhesion layer and the metal layer to the plurality of planar electrodes.

[0150] <11> The method for manufacturing an electronic device described in <9> or <10>, wherein a plurality of grooves are formed in at least one of the adhesion layer and the metal layer of the transfer sheet, with the depth direction being perpendicular to the plane of the transfer sheet, and when the transfer sheet is viewed in a plane, the plurality of grooves have a mesh shape, and the maximum diameter of a unit area surrounded by the plurality of grooves is smaller than the minimum diameter in a direction parallel to the main surface of each of the plurality of planar electrodes.

[0151] <12> The method for manufacturing an electronic device according to any one of <9> to <11>, wherein in the step of transferring the adhesive layer and the metal layer, the transfer sheet is pressure-bonded to the plurality of planar electrodes.

[0152] The present invention can be widely used in electronic devices such as acoustic wave devices and semiconductor devices having conductive films with high bonding quality.

[0153] REFERENCE SIGNS LIST 1, 1A Electronic device 1P Precursor 2 Acoustic wave element 10 Substrate 10a, 10b Main surface 11 Via conductor 12, 53 Insulating film 20 Planar electrode 21, 61, 62 Electrode 30, 30A, 30B, 30C, 30p Transfer sheet 31, 31A, 31p, 31r, 31s, 31t Adhesion layer 32, 32A, 32p, 32r, 32s, 32t Metal layer 33 Release layer 34 Groove 35 Resin film 40 Support substrate 50 Piezoelectric layer 51 Upper electrode 52 Lower electrode

Claims

1. An electronic device comprising: a substrate having first and second principal surfaces opposing each other; an electronic device disposed on the substrate; a planar electrode electrically connected to the electronic device and disposed on the first principal surface; an adhesion layer made of the same first metallic material as the planar electrode and having an amorphous structure; and a metal layer made of a second metallic material different from the first metallic material and having an amorphous structure, the planar electrode, the adhesion layer, and the metal layer being disposed in this order from the first principal surface.

2. The electronic device according to claim 1, wherein at least one of the adhesion layer and the metal layer has a groove structure whose depth direction is perpendicular to the first main surface.

3. The electronic device according to claim 2, wherein at least one of the adhesion layer and the metal layer has a plurality of grooves extending along a direction parallel to the first main surface.

4. The electronic device according to any one of claims 1 to 3, wherein the first metal material is copper, and the second metal material is nickel.

5. The electronic device according to any one of claims 1 to 4, further comprising a bonding layer made of a third metal material different from the first metal material and the second metal material and having an amorphous structure, wherein the planar electrode, the adhesion layer, the metal layer, and the bonding layer are arranged in this order from the first main surface.

6. The electronic device according to claim 5, wherein the first metallic material is copper, the second metallic material is nickel, titanium or palladium, and the third metallic material is gold.

7. The electronic apparatus according to any one of claims 1 to 6, wherein the electronic device includes an acoustic wave element and is disposed on the second main surface side of the substrate.

8. The electronic apparatus according to any one of claims 1 to 6, wherein the electronic device includes a semiconductor element and is disposed on the second main surface side of the substrate.

9. A method for manufacturing an electronic device comprising a substrate and an electronic device formed on the substrate, the method comprising: forming a plurality of planar electrodes on a main surface of the substrate, the planar electrodes being electrically connected to the electronic device; and contacting a transfer sheet having a structure in which an adhesion layer made of the same first metal material as the plurality of planar electrodes and having an amorphous structure, a metal layer made of a second metal material different from the first metal material and having an amorphous structure, and a release layer are laminated in this order with the plurality of planar electrodes with the adhesion layer facing the main surface, thereby transferring the adhesion layer and the metal layer to the plurality of planar electrodes.

10. The method for manufacturing an electronic device described in claim 9, wherein in the step of transferring the adhesion layer and the metal layer, the adhesion layer of the transfer sheet is contacted with the multiple planar electrodes simultaneously to simultaneously transfer the adhesion layer and the metal layer to the multiple planar electrodes.

11. A method for manufacturing an electronic device as described in claim 9 or 10, wherein at least one of the adhesion layer and the metal layer of the transfer sheet has a plurality of grooves with a depth direction perpendicular to the plane of the transfer sheet, and when the transfer sheet is viewed in a plane, the plurality of grooves have a mesh shape, and the maximum diameter of a unit area surrounded by the plurality of grooves is smaller than the minimum diameter in a direction parallel to the main surface of each of the plurality of planar electrodes.

12. The method for manufacturing an electronic device according to any one of claims 9 to 11, wherein in the step of transferring the adhesion layer and the metal layer, the transfer sheet is pressed onto the plurality of planar electrodes.

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