Method for manufacturing elastic wave device, and elastic wave device

Abstract

The present application relates to a method for manufacturing an elastic wave device and an elastic wave device, the method comprising: a pattern forming step of forming at least a part of a pattern by means of an Al-Cu alloy layer in each device chip region in a wafer on which a device chip is to be formed; and a roughening step in which, after the Al-Cu alloy layer is formed, a pad region constituting the Al-Cu alloy layer, which is connected to the bump, is subjected to an etching treatment using an alkaline chemical solution, and protrusions comprising Cu deposits are formed in the pad region, thereby roughening the pad region. The elastic wave device can effectively improve mechanical integration and electrical characteristics of the device chip and the bump which form the elastic wave device.

Description

Technical Field

[0001] The present invention relates to an improvement in a method for manufacturing an elastic wave device suitable for use as a duplexer in a mobile communication device or the like, and to an improvement in the elastic wave device. Background Art

[0002] Elastic wave devices used as duplexers in mobile communication devices, etc., are available in two types: wafer level packaging (WLP / Wafer Level Package) and chip size packaging (CSP / Chip Size Package).

[0003] In both packaging forms, the elastic wave device has an airtight sealed internal space, and on the side of the device chip facing the internal space, a pattern including multiple functional elements and wiring is formed by film formation, and the multiple functional elements include IDT electrodes.

[0004] In addition, in both packaging forms, the elastic wave device is connected to the outside via a bump, which is formed in a protruding shape on one side of the device chip.

[0005] The bottom of the bump is fixed to a pad (bump pad) formed on one side of the device chip, thereby being integrated with the device chip.

[0006] In a WLP type elastic wave device, a solder bump is usually used as the bump, and the pad and the bump are integrated during the heating and solidification process of the solder paste.

[0007] In CSP-type elastic wave devices, Au bumps are generally used as bumps, and the pads and bumps are integrated by ultrasonic vibration.

[0008] In both packaging types, a high degree of mechanical integration between the pad and the bump must be ensured. If this level of integration is not sufficient, the electrical characteristics of the elastic wave device will also be affected. Summary of the invention

[0009] The main problem to be solved by the present invention is to provide a new method and structure for manufacturing an elastic wave device, which can effectively improve the mechanical integration and electrical characteristics of the device chip and bumps constituting the elastic wave device.

[0010] In a first aspect, the present application provides a method for manufacturing an elastic wave device, wherein the elastic wave device comprises a device chip, wherein the device chip is formed by forming a pattern including a plurality of functional elements and wirings on one side, wherein the plurality of functional elements at least include an IDT electrode; and a bump, wherein the bump is formed in a protruding shape on the one side of the device chip, comprising:

[0011] A pattern forming step, forming at least a portion of the pattern through an Al-Cu alloy layer in each device chip region in the wafer where the device chip is to be formed;

[0012] The roughening step is to use an alkaline solution to etch the pad area connected to the bump in the Al-Cu alloy layer after forming the Al-Cu alloy layer, so as to generate a protrusion composed of Cu precipitates in the pad area to roughen it.

[0013] In some of the embodiments, after the roughening step, the following step is included: forming an upper layer so that a protrusion corresponding to the protrusion formed by the Cu precipitate is formed on the upper layer, the upper layer is composed of a conductive metal, and the pad area of ​​the Al-Cu alloy layer is used as the lower layer.

[0014] In some of the embodiments, the number of protrusions on the lower layer is the same as the number of protrusions on the upper layer.

[0015] In some embodiments, the step of generating a protrusion composed of Cu precipitates in the pad region includes:

[0016] Using an alkaline solution, reducing the thickness of the Al-Cu alloy layer 11 to a preset size;

[0017] On the surface side of the Al—Cu alloy layer 11 , Al is dissolved to a predetermined range, so that a part of the Cu precipitates is exposed, thereby generating the protrusions.

[0018] In some of the embodiments, the constituent material of the alkaline solution includes tetramethylammonium hydroxide.

[0019] In a second aspect, the present application provides an elastic wave device having:

[0020] a device chip formed by film-forming a pattern including a plurality of functional elements and wirings on one side, the plurality of functional elements including at least an IDT electrode; and

[0021] A bump formed in a protrusion shape on the one side of the device chip;

[0022] At least the pads on the pattern corresponding to the bumps are formed by an Al-Cu alloy layer,

[0023] Furthermore, a plurality of protrusions composed of Cu precipitates are provided on the surface of the Al—Cu alloy layer.

[0024] In a third aspect, the present application provides an elastic wave device having:

[0025] A device chip formed by film-forming a pattern including a plurality of functional elements and wirings on one side, the plurality of functional elements including at least an IDT electrode; and

[0026] A bump formed in a protrusion shape on the one side of the device chip;

[0027] At least the pad corresponding to the bump on the pattern is formed into a stacked structure, including a lower layer composed of an Al-Cu alloy layer and an upper layer composed of a conductive metal,

[0028] Furthermore, a plurality of upper layer protrusions are provided on the surface of the upper layer, and the upper layer protrusions are formed by protrusions formed of Cu precipitates formed on the lower layer.

[0029] In some of the embodiments, the elastic wave device of the third aspect further includes a wall layer and a top cover layer;

[0030] The wall layer surrounds the functional element; and the top cover layer is formed on the wall layer.

[0031] In some of the embodiments, in the elastic wave device described in the second aspect and the third aspect, the Al-Cu alloy layer has 1 to 5 protrusions per 1 μm 2 .

[0032] In some embodiments, the protrusion in the elastic wave device described in the second and third aspects is configured such that the maximum cross-sectional dimension in a direction orthogonal to its protruding direction is in the range of 100nm to 400nm, and the protruding dimension is in the range of 40nm to 50nm.

[0033] According to the method for manufacturing an elastic wave device according to the first aspect, the protrusion can be easily and appropriately provided on the pad during the manufacturing process of the elastic wave device.

[0034] In the elastic wave device according to the second aspect, the plurality of protrusions engage with the bumps at the fixing portion between the pads and the bumps, thereby effectively improving the mechanical integration and electrical characteristics of the device chip and the bumps.

[0035] In the elastic wave device according to the third aspect, the plurality of upper protrusions engage with the bumps at the fixing portion between the pads and the bumps, thereby effectively improving the mechanical integration and electrical characteristics of the device chip and the bumps.

[0036] The details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0038] Figure 1 It is a plan view showing the structure of an elastic wave device (first example) according to one embodiment of the present invention.

[0039] Figure 2 is a cross-sectional structural diagram of the first embodiment, showing the first embodiment in Figure 1 Cross-sectional view at the AA line.

[0040] Figure 3 yes Figure 2 An enlarged structural diagram of the main parts.

[0041] Figure 4 1 is a structural diagram showing an example of a circuit formed on a device chip constituting the first embodiment described above.

[0042] Figure 5 FIG. 1 is a diagram showing a structure of an example of a resonator formed on a device chip constituting the first embodiment.

[0043] Figure 6 It is a cross-sectional structural diagram of the main part of a modified example (second embodiment) of the structural part of the above-mentioned first embodiment.

[0044] Figure 7 It is a cross-sectional structural diagram of the main parts of an elastic wave device (third example) according to one embodiment of the present invention.

[0045] Figure 8 It is a cross-sectional structural diagram showing the main parts of the first embodiment during the manufacturing process.

[0046] Fig. 9 yes Figure 8 An enlarged structural diagram of the main parts.

[0047] Fig.10 It means according to Figure 8 An enlarged cross-sectional structural view of the main part after processing in a process subsequent to the illustrated process.

[0048] Fig.11 It means according to Fig.10 An enlarged cross-sectional structural view of the main part after processing in a process subsequent to the illustrated process.

[0049] Fig.12 FIG. 1 is a diagram-substituted photograph showing, by way of example, the appearance of the surface of a pad formed on a device chip that can constitute the first embodiment described above.

[0050] In the figure: 1, elastic wave device; 2, packaging substrate; 2a, one side of the packaging substrate; 2b, the other side of the packaging substrate; 2c, wiring; 2d, external connection terminal; 2e, outer edge of the packaging substrate; 3, device chip; 3a, functional surface; 3b, non-functional surface; 3c, side surface; 3d, outer edge of the device chip; 4, sealing part; 4a, lateral part; 4b, longitudinal part; 5, gap; 6, internal space; 7, functional element; 7a, 7aa, 7ab, resonator; 7b, IDT electrode; 7c, reflector; 7d, 7f, electrode finger; 7e, 7g, bus bar; 8, wiring; 9, pattern; 10, pad; 10a, lower layer; 10b, upper layer; 11, Al-Cu alloy; 11a, pad area; 11b, precipitate; 12, protrusion; 13, upper layer protrusion; 14, bump; 15, circuit; 15a, transmitting side filter; 15b, receiving side filter; 15c, external connection terminal; 15d, grounding; 16, wall layer; 17, top cover layer; 18, bottom hole; 18a, bottom of hole; 19, chip; 19a, area. DETAILED DESCRIPTION

[0051] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0052] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the", "these" and the like in this application do not represent quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether directly or indirectly. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. Usually, the character " / " indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0053] The following is based on Figures 1 to 11 A typical embodiment of the present invention will be described below. The elastic wave device 1 of this embodiment is suitable for use as a duplexer in mobile communication equipment and the like.

[0054] In addition, the structural diagrams shown in the various figures are intended to facilitate understanding of the structure of the present invention. In addition, for ease of explanation, the dimensional ratios of the drawings are exaggerated and may be different from their actual ratios.

[0055] Figures 1 to 6 The first and second embodiments of the present invention applied to a chip size package (CSP) elastic wave device are shown.

[0056] The elastic wave device 1 includes a device chip 3 on one side 2a of a package substrate 2. The device chip 3 includes a functional element 7 on a functional surface 3a facing the package substrate 2. The functional element 7 is typically a resonator 7a including an IDT electrode 7b.

[0057] Typically, the device chip 3 is in the shape of a quadrilateral plate, with one side of 0.5 mm to 1 mm and a thickness of 0.15 mm to 0.2 mm. In addition, the package substrate 2 is in the shape of a quadrilateral plate, with one side of 0.7 mm to 3 mm and a thickness of 0.15 mm to 0.2 mm. The thickness of the elastic wave device 1 is approximately 0.4 mm to 0.6 mm.

[0058] Figure 2 In the figure, reference numeral 3 denotes a device chip, reference numeral 3a denotes one side of the device chip, i.e., a functional side on which the functional element 7 is formed, reference numeral 3b denotes a non-functional side opposite to the functional side 3a, reference numeral 7a denotes a resonator, and reference numeral 10 denotes a pad on which a bump 14 described below is fixed, which will serve as a wiring 8 formed on the functional side 3a (see Figure 4 ) external output terminal.

[0059] A bump 14 is inserted between the device chip 3 and the package substrate 2 to electrically connect the pad 10 and the wiring 2c on the package substrate 2 and form a gap 5. The bump 14 is a protruding electrode made of a conductive metal (such as gold or solder), formed on the functional surface 3a of the device chip 3, and protruding in a direction orthogonal to the functional surface 3a.

[0060] That is, elastic wave device 1 includes bumps 14 formed in a protruding shape on one surface (functional surface 3 a ) of device chip 3 .

[0061] External connection terminals 2 d are formed on a surface 2 b of the package substrate 2 opposite to the surface 2 a on which the device chip 3 is mounted, for connecting the elastic wave device 1 to a module substrate (not shown) or the like.

[0062] The package substrate 2 is in a quadrilateral plate shape when viewed from a direction perpendicular to one surface 2 a thereof, and the device chip 3 is in a quadrilateral plate shape having a smaller area than the package substrate 2 when viewed from a direction perpendicular to its functional surface 3 a thereof.

[0063] Moreover, the device chip 3 is mounted on the packaging substrate 2 in such a manner that, at any position in the direction of rotation around the center of the device chip 3, a gap is formed between an outer edge 3d of the device chip 3 (a portion where a functional surface 3a of the device chip 3 meets a side surface 3c) and an outer edge 2e of the packaging substrate 2 (a portion where one surface 2a of the packaging substrate 2 meets a side surface on its thickness side).

[0064] In this manner, after the device chip 3 is mounted on one surface 2 a of the package substrate 2 , the sealing portion 4 is formed on the one surface 2 a of the package substrate 2 .

[0065] Typically, the sealing portion 4 is made of a synthetic resin having insulating properties.

[0066] The sealing portion 4 comprises: a transverse portion 4a, covering the non-functional surface 3b of the device chip 3 opposite to the functional surface 3a of the device chip 3; and a longitudinal portion 4b, following the transverse portion 4a, covering the side surface 3e and leading to the one surface 2a of the packaging substrate 2, the side surface 3e forming the thickness of the device chip 3 between the functional surface 3a and the non-functional surface 3b; and forming an internal space 6 (a hollow structural portion or even an air cavity) between the functional surface 3a of the device chip 3 and the one surface 2a of the packaging substrate 2.

[0067] The longitudinal portion 4 b of the sealing part 4 hermetically seals the gap 5 around the entire periphery of the device chip 3 , thereby forming the internal space 6 between the functional surface 3 a of the device chip 3 and the one surface 2 a of the package substrate 2 .

[0068] In the illustrated example, sealing portion 4 formed in this manner gives elastic wave device 1 a hexahedral appearance.

[0069] A portion of the functional surface 3 a of the device chip 3 that faces the internal space 6 includes a functional element including an IDT electrode 7 b , which is a resonator 7 a in the example shown in the figure.

[0070] The device chip 3 has the function of propagating elastic waves. Typically, the device chip 3 uses a piezoelectric body such as lithium tantalate or lithium niobate. In addition, the device chip 3 can also be formed by stacking the above-mentioned piezoelectric body on a support body such as sapphire, silicon, alumina, spinel, crystal or glass.

[0071] Figure 4 1 shows the concept of an example of the circuit 15 provided on one device chip 3. Reference numeral 15a denotes a transmission side filter, reference numeral 15b denotes a reception side filter, reference numeral 15c denotes an external connection terminal, reference numeral 7aa denotes a resonator 7a connected in series between the external connection terminals 15c, reference numeral 7ab denotes a resonator 7a connected in parallel between the external connection terminals 15c, reference numeral 15d denotes a ground, and reference numeral 8 denotes a wiring. The number and arrangement of the resonators 7a may be changed as required.

[0072] Figure 5 An example of a resonator 7a constituting a duplexer is shown. The resonator 7a has an IDT electrode 7b and a reflector 7c formed by sandwiching the IDT electrode 7b. The IDT electrode 7b is composed of an electrode pair, and each electrode pair connects a plurality of electrode fingers 7d arranged in parallel to each other at one end through a bus bar 7e so that the length direction of each electrode pair intersects with the propagation direction x of the elastic wave. The reflector 7c connects the ends of a plurality of electrode fingers 7f arranged in parallel through a bus bar 7g so that the length direction of the reflector 7c intersects with the propagation direction x of the elastic wave.

[0073] The pattern 9 is formed by photolithography technology and includes the functional element 7 and the wiring 8 made of a conductive metal.

[0074] exist Figures 1 to 5 In the first embodiment shown, at least the pad 10 connected to the bump 14 in the pattern 9 has a laminated structure including a lower layer 10a composed of an Al-Cu alloy layer 11 and an upper layer 10b composed of a conductive metal.

[0075] The lower layer 10 a is formed on the functional surface 3 a of the device chip 3 before the upper layer 10 b , and the upper layer 10 b is formed on the lower layer 10 a .

[0076] like Figure 3 As shown, a plurality of protrusions 12 composed of Cu precipitates 11b are formed on the lower layer 10a.

[0077] At the same time, a plurality of upper layer protrusions 13 are provided on the surface of the upper layer 10b, which are formed by protruding from the protrusions 12 formed on the lower layer 10a.

[0078] The upper layer 10b is formed on the lower layer 10a with a preset thickness. At the formation position of the protrusion 12 of the lower layer 10a, the upper layer 10b is raised by an amount equal to the height of the protrusion 12. Through the protrusion, the above-mentioned upper layer protrusions 13 are formed on the surface of the upper layer 10b. The number of the upper layer protrusions 13 is the same as the number of the protrusions 12 formed on the lower layer 10a.

[0079] That is, the surface of the pad 10 is composed of the upper layer 10 b , and a plurality of upper layer protrusions 13 are formed on the upper layer 10 b , so that the surface of the pad 10 is roughened.

[0080] According to this structure, in elastic wave device 1 of the present embodiment, a plurality of upper protrusions 13 engage with bumps 14 at the fixed portion between pads 10 and bumps 14. This effectively improves the mechanical integration and electrical characteristics of the device chip and bumps 14.

[0081] Preferably, on the Al-Cu alloy layer, every 1 μm 2 The upper layer 10b also has 1 to 5 upper layer protrusions 13 per 1 μm2 (see Fig.12 ).

[0082] In addition, preferably, the protrusion 12 of the lower layer 10a is configured such that the maximum cross-sectional dimension in the direction perpendicular to the protruding direction thereof is in the range of 100nm to 400nm, and the protruding dimension thereof is in the range of 40nm to 50nm. Thus, the upper layer 10b is also formed with an upper layer protrusion 13, and the maximum cross-sectional dimension in the direction perpendicular to the protruding direction thereof is in the range of 100nm to 400nm, and the protruding dimension thereof is in the range of 40nm to 50nm (refer to Fig.12 ).

[0083] exist Figure 6 In the second embodiment shown, at least the pad region 11a is composed of a layer of the Al-Cu alloy layer 11, and the pad region 11a is the pad 10 connected to the bump 14 in the pattern 9. In addition, in the pad region 11a, the surface of the Al-Cu alloy layer 11 has a plurality of protrusions 12 composed of Cu precipitates 11b.

[0084] The surface of the pad 10 is roughened by the plurality of protrusions 12 .

[0085] According to this structure, in elastic wave device 1 of the present embodiment, a plurality of protrusions 12 engage with bumps 14 at the fixed portion between pads 10 and bumps 14. This effectively improves the mechanical integration and electrical characteristics of the device chip and bumps 14.

[0086] Preferably, in the pad region 11 a , the Al—Cu alloy layer 11 includes 1 to 5 protrusions 12 per 1 μm 2 .

[0087] Preferably, the protrusions 12 of the Al—Cu alloy layer 11 have a maximum cross-sectional dimension in a direction perpendicular to the protruding direction of the protrusions 12 ranging from 100 nm to 400 nm, and a protruding dimension ranging from 40 nm to 50 nm.

[0088] Figure 7 A third embodiment of the present invention is shown in which an elastic wave device 1 is applied to a wafer level package (WLP).

[0089] Figure 7 , reference numeral 3 denotes a device chip 3, reference numeral 3a denotes the functional surface 3a, reference numeral 7 denotes a functional element, reference numeral 6 denotes an internal space, reference numeral 16 denotes a wall layer made of synthetic resin formed on the functional surface 3a to surround the functional element 7, and reference numeral 17 denotes a top cover layer made of synthetic resin formed on the wall layer 16 to form the internal space 6 in cooperation with the functional surface 3a and the wall layer 16. That is, the third embodiment is constituted by a laminate of the device chip 3, the wall layer 16, and the top cover layer 17, and does not have a package substrate 2 as in the first embodiment.

[0090] In the third embodiment, the device chip 3 is also in a quadrilateral plate shape, and is formed into a typical flat hexahedron shape by stacking a wall layer 16 and a top cover layer 17 on its functional surface 3a, which is omitted from the illustration. In addition, the third embodiment is formed so that a bump 14 protrudes on one side of the top cover layer 17, and is mounted on the module substrate using the bump 14. Figure 7 The cross section of a portion where a bump 14 is formed in the third embodiment is shown, and the cross section direction is orthogonal to the functional surface 3 a of the device chip 3 .

[0091] A bottomed hole 18 is formed outside the above-mentioned internal space 6, which penetrates the wall layer 16 and the top cover layer 17. The bottom of the hole 18a is the above-mentioned functional surface 3a. A solder pad 10 corresponding to the above-mentioned bump 14 in the pattern 9 is provided on the bottom of the hole 18a. The pattern 9 includes the above-mentioned functional element 7 and wiring 8.

[0092] The pad 10 is formed into a laminated structure including a lower layer 10 a formed of an Al—Cu alloy layer 11 and an upper layer 10 b formed of a conductive metal.

[0093] A plurality of protrusions 12 composed of Cu precipitates 11 b are formed on the lower layer 10 a .

[0094] At the same time, a plurality of upper layer protrusions 13 are provided on the surface of the upper layer 10b, which are formed by protruding from the protrusions 12 formed on the lower layer 10a.

[0095] The upper layer 10b is formed on the lower layer 10a with a preset thickness. At the formation position of the protrusion 12 of the lower layer 10a, the upper layer 10b is raised by an amount equal to the height of the protrusion 12. Through the protrusion, the above-mentioned upper layer protrusions 13 are formed on the surface of the upper layer 10b. The number of the upper layer protrusions 13 is the same as the number of the protrusions 12 formed on the lower layer 10a.

[0096] That is, the surface of the pad 10 is composed of the upper layer 10 b , and a plurality of upper layer protrusions 13 are formed on the upper layer 10 b , so that the surface of the pad 10 is roughened.

[0097] According to this structure, in the elastic wave device 1 of the third embodiment, the plurality of upper protrusions 13 engage with the bumps 14 at the fixing portion between the pads 10 and the bumps 14. This can effectively improve the mechanical integration and electrical characteristics of the device chip 3 and the bumps 14.

[0098] The elastic wave device 1 can be manufactured conveniently and appropriately through the following process. Next, the manufacturing method of the first embodiment will be described.

[0099] First, on the region 19a of the wafer 19 where the device chip 3 is to be formed, a pattern 9 ( Figure 8 , Fig. 9 ). Typically, the film formation can be achieved by photolithography and vacuum evaporation / lift-off.

[0100] In the example shown in the figure, the functional element 7 and the lower layer 10 a of the pad 10 are formed of an Al—Cu alloy layer 11 .

[0101] Next, after the Al-Cu alloy layer 11 is formed, the pad region 11a in the Al-Cu alloy layer 11 is etched using an alkaline solution to produce a protrusion 12 consisting of Cu precipitates 11b in the pad region 11a, thereby roughening the pad region 11a ( Fig.10 / roughening step). The region other than the pad region 11a in the Al-Cu alloy layer 11 is masked with a resist to prevent the layer from being etched.

[0102] The Al—Cu alloy layer 11 includes granular Cu precipitates 11 b having a high Cu density.

[0103] The etching process is managed to reduce the thickness of the Al-Cu alloy layer 11 to a preset size using an alkaline solution, thereby dissolving Al to a preset range on the surface side of the Al-Cu alloy layer 11, exposing a portion of the Cu precipitate 11b, thereby generating the protrusion 12.

[0104] It was confirmed that the plurality of protrusions 12 can be appropriately formed on the surface of the Al—Cu alloy layer 11 by using a tetramethylammonium hydroxide aqueous solution having a pH value of about pH=13 as the alkaline chemical solution.

[0105] Next, after the roughening step, an upper layer 10b is formed, so that an upper layer protrusion 13 corresponding to the protrusion 12 composed of the Cu precipitate 11b is formed on the upper layer 10b, and the upper layer 10b is composed of a conductive metal, with the pad area 11a of the Al-Cu alloy layer 11 as the lower layer 10a ( Fig.11 ).

[0106] Typically, the upper layer 10 b is made of Al and formed by vacuum evaporation.

[0107] At the formation position of the protrusion 12 of the lower layer 10a, the upper layer 10b is raised by the same amount as the height of the protrusion, thereby forming the above-mentioned upper layer protrusions 13 on the surface of the upper layer 10b. The number of the upper layer protrusions 13 is the same as the number of protrusions formed on the lower layer 10a.

[0108] In the example shown in the figure, the lower layer 10 a is etched so that the outer edge of the surface thereof has a rising portion 10 c , and the upper layer 10 b is formed on the lower layer 10 a within the rising portion 10 c .

[0109] In the first embodiment, the pad 10 is formed by the upper layer 10b and the lower layer 10a. The bump 14 is formed on the pad 10 thus formed, and then the wafer 19 is cut into each region where the device chips 3 are to be formed, and then each region where one elastic wave device 1 is to be formed is formed on the collective substrate where the package substrate 2 is to be formed, and the device chip 3 is flip-chip mounted using the bump 14, and then the sealing portion 4 is formed, and then the collective substrate is cut for each region where one elastic wave device 1 is formed, thereby generating a plurality of elastic wave devices 1 having the structure of the first embodiment.

[0110] The manufacturing method of the second embodiment does not include Fig.11 The process of forming the upper layer 10b in the first embodiment is shown. The other processes of the manufacturing method of the second embodiment are the same as those of the first embodiment, and thus the description thereof is omitted.

[0111] Since the third embodiment is a WLP structure, in each region on the wafer 19 where each device chip 3 is to be formed, after forming the lower layer 10a and the upper layer 10b in the same manner as in the first embodiment, the wall layer 16, the top cover layer 17 and the bump 14 are formed, and then the wafer 19 is cut in each region to generate a plurality of elastic wave devices 1 having the structure of the third embodiment.

[0112] The expressions and terms used in the present invention are for illustrative purposes only and should not be considered as limiting. The use of "include", "have", "have", "include" and their variations as used herein means including the following listed items, their equivalents and additional items.

[0113] The term "embodiment" in this application refers to a specific feature, structure or characteristic described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various locations in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is clearly or implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0114] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations, corrections and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. A method for manufacturing an elastic wave device, the elastic wave device comprising a device chip, the device chip being formed by film-forming a pattern including a plurality of functional elements and wirings on one surface, the plurality of functional elements including at least an IDT electrode; and a bump, the bump being formed in a protruding shape on the one surface of the device chip, characterized in that: include: A pattern forming step, forming at least a portion of the pattern through an Al-Cu alloy layer in each device chip region in the wafer where the device chip is to be formed; The roughening step is to use an alkaline solution to etch the pad area connected to the bump in the Al-Cu alloy layer after forming the Al-Cu alloy layer, so as to generate a protrusion composed of Cu precipitates in the pad area to roughen it.

2. The method for manufacturing an elastic wave device according to claim 1, wherein: After the roughening step, the method includes forming an upper layer having protrusions corresponding to the protrusions formed by the Cu precipitates, wherein the upper layer is made of a conductive metal and the pad region of the Al-Cu alloy layer is used as a lower layer.

3. The method for manufacturing an elastic wave device according to claim 2, wherein: The number of protrusions on the lower layer is the same as the number of protrusions on the upper layer.

4. The method for manufacturing an elastic wave device according to claim 1, wherein: The step of generating a protrusion composed of Cu precipitates in the pad region comprises: Using an alkaline solution, reducing the thickness of the Al-Cu alloy layer 11 to a preset size; On the surface side of the Al—Cu alloy layer 11 , Al is dissolved to a predetermined range, so that a part of the Cu precipitates is exposed, thereby generating the protrusions.

5. The method for manufacturing an elastic wave device according to claim 1, wherein: The constituent material of the alkaline solution includes tetramethylammonium hydroxide.

6. An elastic wave device, characterized in that: have: a device chip formed by film-forming a pattern including a plurality of functional elements and wirings on one side, the plurality of functional elements including at least an IDT electrode; and A bump formed in a protrusion shape on the one side of the device chip; At least the pads on the pattern corresponding to the bumps are formed by an Al-Cu alloy layer, Furthermore, a plurality of protrusions composed of Cu precipitates are provided on the surface of the Al—Cu alloy layer.

7. An elastic wave device, characterized in that: have: A device chip formed by film-forming a pattern including a plurality of functional elements and wirings on one side, the plurality of functional elements including at least an IDT electrode; and A bump formed in a protrusion shape on the one side of the device chip; At least the pad corresponding to the bump on the pattern is formed into a stacked structure, including a lower layer composed of an Al-Cu alloy layer and an upper layer composed of a conductive metal, Furthermore, a plurality of upper layer protrusions are provided on the surface of the upper layer, and the upper layer protrusions are formed by protrusions formed of Cu precipitates formed on the lower layer.

8. The elastic wave device according to claim 7, characterized in that: The elastic wave device also includes a wall layer and a top cover layer; The wall layer surrounds the functional element; and the top cover layer is formed on the wall layer.

9. The elastic wave device according to claim 6 or 7, characterized in that: The Al-Cu alloy layer has 1 to 5 protrusions per 1 μm 2 .

10. The elastic wave device according to claim 6 or 7, characterized in that: The protrusion is configured such that the maximum dimension of the cross section in a direction perpendicular to the protruding direction thereof is in the range of 100 nm to 400 nm, and the protruding dimension thereof is in the range of 40 nm to 50 nm.

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