Method for manufacturing a surface acoustic wave device

Abstract

A method for manufacturing an elastic surface wave device includes: a process of forming a metal pattern including an IDT electrode for exciting an elastic surface wave and a plurality of soldering pads for three-dimensional wiring on a piezoelectric substrate; a process of forming a support layer in a region other than at least a part of a region where the IDT electrode is formed and a region where the soldering pads for three-dimensional wiring are formed; a process of forming a cover layer on the support layer in a region other than at least a part of the region where the soldering pads for three-dimensional wiring are formed; and a process of filling a metal for three-dimensional wiring in a space partially surrounded by the plurality of soldering pads for three-dimensional wiring, the support layer, and the cover layer using a mask, and in the soldering pads for three-dimensional wiring, an opening of a soldering pad for external connection of the elastic surface wave device is larger than an opening of a soldering pad for internal wiring of the elastic surface wave device, whereby a WLP type elastic surface wave device having more layers of wiring than in the past, improved freedom of design of wiring, and stable characteristics by lowering impedance of a ground wiring can be manufactured.

Description

Technical Field

[0001] This invention relates to an elastic surface wave device, and more particularly to an elastic surface wave device with a wafer level package (WLP) structure. Background Technology

[0002] In the front-end modules of mobile communication terminals such as smartphones, surface wave devices are used as bandpass filters. In recent years, the modularization of the wireless components in portable information terminals such as mobile phones and smartphones has been continuously developing, demanding miniaturization and lower height.

[0003] Therefore, the packaging structure technology of surface wave devices has also been improved, and a WLP (Surface Plate Laying) that uses the chip of the surface wave device itself for packaging has been proposed. In the surface wave device, IDT (Interdigital Transducer) electrodes are formed on the piezoelectric substrate, and packaging is performed while ensuring that there is a hollow space above the IDT electrodes.

[0004] In WLP-type elastic surface wave devices, the piezoelectric substrate itself is used to form a hollow encapsulation.

[0005] Patent document 1WO2018 / 159111 discloses an example of a technology for a WLP-type elastic surface wave device.

[0006] As disclosed in Patent Document 1, the existing WLP-type elastic surface wave device uses the piezoelectric substrate itself for packaging instead of using a wiring substrate, which greatly limits the number of wiring layers.

[0007] Furthermore, in order to stabilize the characteristics of the elastic surface wave device, it is best to ensure that the wiring of its grounding pattern is wide and the area is large. However, in the existing WLP type elastic surface wave device structure, it is difficult to achieve this without increasing the size of the piezoelectric substrate itself. Summary of the Invention

[0008] The present invention was made in view of the above-mentioned problems, and its object is to manufacture a method for manufacturing a WLP type elastic surface wave device. Compared with the prior art, the WLP type elastic surface wave device can increase the number of wiring layers, improve the degree of freedom of wiring design, and stabilize the characteristics by reducing the impedance of the grounding wiring.

[0009] To achieve the aforementioned objective, the manufacturing method of the elastic surface wave device of the present invention includes:

[0010] The process of forming a metal pattern: forming a metal pattern containing an IDT electrode that excites elastic surface waves and several three-dimensional wiring pads on a piezoelectric substrate;

[0011] The process of forming the support layer: A support layer is formed in the area outside the region where the IDT electrode is formed;

[0012] The process of forming the capping layer: A capping layer is formed by covering the IDT electrode on the support layer with a gap;

[0013] Exposure process: Exposing the solder pads for the aforementioned three-dimensional wiring;

[0014] Process for filling metal for three-dimensional wiring: Using a mask, the space formed in the exposure process that exposes the plurality of three-dimensional wiring pads is filled with metal for three-dimensional wiring, and the opening of the mask on the outer connection pad of the elastic surface wave device is larger than the opening on the inner wiring pad of the elastic surface wave device.

[0015] To achieve the aforementioned goal, on the other hand, the method for manufacturing the elastic surface wave device of the present invention includes:

[0016] The process of forming a metal pattern: forming a metal pattern containing an IDT electrode that excites elastic surface waves and several three-dimensional wiring pads on a piezoelectric substrate;

[0017] The process of forming a support layer: A support layer is formed in a region other than at least a portion of the region where the IDT electrode is formed and the region where the three-dimensional wiring pad is formed;

[0018] The process of forming the capping layer: A capping layer is formed on the support layer by covering at least a portion of the area of ​​the IDT electrode and the three-dimensional wiring pad with a gap;

[0019] Process of filling three-dimensional wiring metal: using a mask, three-dimensional wiring metal is filled in a space partially surrounded by the plurality of three-dimensional wiring pads, the support layer and the cover layer, wherein the opening of the mask on the outer connection pad of the elastic surface wave device is larger than the opening on the inner wiring pad of the elastic surface wave device among the plurality of three-dimensional wiring pads.

[0020] In one embodiment of the present invention, during the process of forming the support layer, the support layer surrounds the IDT electrode.

[0021] In one embodiment of the present invention, during the process of forming the capping layer, the IDT electrode is enclosed by the support layer and the capping layer.

[0022] In one embodiment of the invention, the metal used for the three-dimensional wiring is solder or an alloy containing solder.

[0023] In one embodiment of the invention, during the exposure process, at least two of the internal wiring pads are exposed in the same space.

[0024] In one embodiment of the invention, during the manufacturing process of the filling three-dimensional wiring metal, at least two of the internal wiring pads are electrically connected by the three-dimensional wiring metal.

[0025] In one embodiment of the present invention, during the manufacturing process of the filling three-dimensional wiring metal, the three-dimensional wiring metal formed on the external connection pad is higher than the three-dimensional wiring metal formed on the internal wiring pad.

[0026] In one embodiment of the invention, the diameter of the opening on the external connection pad is between 100 μm and 120 μm, and the diameter of the opening on the internal wiring pad is between 25 μm and 50 μm.

[0027] In one embodiment of the invention, the solder pads for the three-dimensional wiring are made of a conductive material selected from aluminum (Al) alloys or elemental aluminum (Al).

[0028] The beneficial effects of the present invention are as follows: According to the manufacturing method of the elastic surface wave device of the present invention, a manufacturing method of WLP type elastic surface wave device can be provided, which can manufacture a device with more wiring layers than before, improve the degree of freedom of wiring design, and stabilize the characteristics of WLP type elastic surface wave device by reducing the impedance of grounding wiring. Attached Figure Description

[0029] Figure 1 A top view of the elastic surface wave device 1 manufactured by the manufacturing method of the present invention.

[0030] Figure 2 A cross-sectional view of the elastic surface wave device 1 manufactured by the manufacturing method of the present invention.

[0031] Figure 3 This is a diagram illustrating the manufacturing method of Embodiment 1 of the present invention.

[0032] Figure 4 A top view showing an elastic surface wave resonator.

[0033] Figure 5 This is a view showing an example of a filter structure that can be used in the elastic surface wave device 1.

[0034] Figure 6 This is a diagram illustrating the manufacturing method of Embodiment 2 of the present invention. Detailed Implementation

[0035] The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0036] (Example 1)

[0037] Figure 1 A top view of the elastic surface wave device 1 manufactured by the manufacturing method of the present invention.

[0038] Figure 1 A diagram showing the elastic surface wave device 1 as viewed from the mounting surface side. (See diagram.) Figure 1 As shown, the surface wave device 1 manufactured by the manufacturing method of the first embodiment has a three-dimensional wiring metal 15a for external connection and a three-dimensional wiring metal 15b for internal wiring on the mounting surface side. Furthermore, the portion other than the three-dimensional wiring metal 15b is covered with a covering layer 13. The area indicated by the dashed line is the cavity region 10, a sealed space formed to allow the functional components of the surface wave device to mechanically operate and be excited.

[0039] Figure 2 A cross-sectional view of the elastic surface wave device 1 manufactured by the manufacturing method of the present invention.

[0040] Figure 2 yes Figure 1 The structural cross-sectional view of the elastic surface wave device 1 along section line AA is shown. The elastic surface wave device 1 includes a piezoelectric substrate 3, an IDT electrode 5 formed on a main surface (i.e., the upper surface) of the piezoelectric substrate 3, a wiring pattern 7, three-dimensional wiring pads 9 (external connection pads 9a and internal wiring pads 9b), and three-dimensional wiring metal 15 (external connection three-dimensional wiring metal 15a and internal wiring three-dimensional wiring metal 15b) formed on the three-dimensional wiring pads 9 and the piezoelectric substrate 3.

[0041] In addition, the elastic surface wave device 1 also includes a support layer 11, which is disposed on the area outside the region where the IDT electrode 5 is formed and the region where the three-dimensional wiring metal 15 is formed. The cover layer 13 and the support layer 11 together seal the cavity region 10 where the IDT electrode 5 is formed, making the cavity region 10 a sealed space.

[0042] The elastic surface wave device 1 may also include a support substrate 17 formed on another main surface (i.e., the bottom) of the piezoelectric substrate 3. The support substrate 17 may be made of high-resistivity silicon, gallium arsenide, sapphire, polycrystalline alumina, or glass. However, the material of the support substrate 17 is not limited to these. The thickness of the support substrate 17 may be, for example, 200 μm.

[0043] The surface acoustic wave (SAW) device 1 can be any of a filter, resonator, delay line, and trap. Furthermore, the elastic wave excited by the IDT electrode 5 can be any of a Rayleigh wave or an SH wave. Further, when the SAW device 1 is a filter, it can be any of a resonator-type filter or a transversal filter.

[0044] Figure 3 This is an explanatory diagram illustrating the manufacturing method of Embodiment 1 of the present invention.

[0045] In manufacturing the elastic surface wave device 1, firstly as follows: Figure 3 As shown in (a), an IDT electrode 5, a wiring pattern 7, and a three-dimensional wiring pad 9 are formed on the upper surface of the piezoelectric substrate 3.

[0046] The piezoelectric substrate 3 is a substrate made of a piezoelectric material. Examples of piezoelectric materials include lithium tantalate (LiTaO3), lithium niobate (LiNbO3), quartz crystal (SiO2), lithium tetraborate (Li2B4O7), zinc oxide (ZnO), potassium niobate (KNbO3), and lanthanum gallium silicate (La3Ga3SiO2). 14 (e.g., single crystals)

[0047] The IDT electrode 5, wiring pattern 7, and 3D wiring pad 9 are thin films made of conductive materials. Conductive materials can be, for example, aluminum (Al) alloys, such as aluminum-copper (Al-Cu) alloys, or elemental aluminum (Al). Furthermore, the IDT electrode 5, wiring pattern 7, and 3D wiring pad 9 can also be thin films composed of several layers of different conductive materials stacked together.

[0048] The planar shape of the IDT electrode 5, as described later, is formed by at least a pair of comb-shaped electrodes arranged with their electrode fingers facing each other and interlocking. The IDT electrode 5 functions as an excitation electrode and can excite elastic surface waves on the piezoelectric substrate 3 according to the excitation signal applied to the pair of comb-shaped electrodes.

[0049] The surface acoustic wave (SAW) device 1 does not necessarily have to be composed of a single IDT electrode 5; it can also be composed of several IDT electrodes 5 connected in series or in parallel. If several IDT electrodes 5 are connected, a trapezoidal SAW filter, a lattice SAW filter, or a dual-mode SAW filter can be constructed.

[0050] The wiring pattern 7 is electrically connected to the IDT electrode 5. The wiring pattern 7 is also electrically connected to the three-dimensional wiring pad 9.

[0051] The IDT electrode 5, the wiring pattern 7, and the three-dimensional wiring pad 9 are formed by patterning thin films formed by methods such as sputtering, evaporation, and chemical vapor deposition (CVD) into predetermined shapes using photolithography techniques such as stepper lithography and reactive ion etching (RIE).

[0052] When the IDT electrode 5, the wiring pattern 7, and the three-dimensional wiring pad 9 are formed by the above method, the IDT electrode 5, the wiring pattern 7, and the three-dimensional wiring pad 9 can be made of the same material and in the same process.

[0053] To confine the surface waves, reflector electrodes can be formed on the piezoelectric substrate 3. Viewed from the IDT electrode 5, the reflector electrodes are positioned along both propagation directions of the surface waves. With the reflector electrodes provided, both the reflector electrodes and the IDT electrode 5 can be formed from the same material and in the same process.

[0054] Next, as Figure 3 As shown in (b), a support layer 11 is formed in a region other than the region where the IDT electrode 5 is formed. The support layer 11 may be formed at least in the region other than the region where the IDT electrode 5 is formed, but it may not be formed in the region where the three-dimensional wiring metal 15 is formed.

[0055] The support layer 11 can also be formed by patterning the thin film formed on the piezoelectric substrate 3 using a general film forming method, or by attaching a separately prepared thin film to the piezoelectric substrate 3.

[0056] When the support layer 11 is formed using the aforementioned method, it can be formed, for example, by patterning and curing a thin film of photoresist using photolithography. In this case, the photoresist is, for example, a photosensitive resin such as an epoxy resin, a polyimide resin, a BCB (benzocyclobutene) resin, or an acrylic fiber resin.

[0057] The methods for forming the photoresist are represented by methods using photosensitive dry film and methods using photosensitive liquid photoresist. When using photosensitive dry film, a vacuum bonding device can be used to tightly bond the photosensitive dry film to the wafer or substrate surface of the elastic surface wave device.

[0058] When using a photosensitive dry film, a relatively thick support layer 11 with excellent adhesion, exceeding 10 μm in thickness, can be formed.

[0059] When using photosensitive liquid photoresist, it is formed by coating the photoresist liquid, for example, by spin coating or printing. Preferably, the photoresist is formed into a thin film by spin coating.

[0060] When photoresist is formed into a thin film by spin coating, even if the underlying structure has a height difference, the photoresist film can be formed without gaps between it and the underlying structure, and the support layer 11 with excellent adhesion can be formed.

[0061] The photoresist film formed in the above manner undergoes an exposure process and a development process to be processed into a support layer 11 formed in the area other than the area where the IDT electrode 5 is formed. The thickness of the support layer 11 is, for example, 20 μm.

[0062] Next, a thin film-like cover layer 13 is formed on the upper surface of the support layer 11, and the support layer 11 is bonded to the cover layer 13. This allows the cover layer 13, which provides a sealed vibration space (cavity region 10), to be formed in the region where the IDT electrode 5 is formed.

[0063] In order to be placed on the upper surface of the support layer 11, the film is pressed and bonded by a laminating machine with rollers while controlling the temperature, and the temperature and pressure are appropriately controlled to bond the cover layer 13 to the upper surface of the support layer 11.

[0064] To bond the support layer 11 to the cover layer 13, the support layer 11 and the cover layer 13 can be heated or exposed to light, depending on the selected material. For example, if the material of the support layer 11 and the cover layer 13 is epoxy resin, it is preferable to heat the support layer 11 and the cover layer 13 to 100°C. The cover layer 13 formed by the above method can seal the IDT electrode 5 while forming the vibration space (cavity region 10), thus slowing down the oxidation of the IDT electrode 5. The thickness of the cover layer 13 can be, for example, between 20 μm and 45 μm.

[0065] If the support layer 11 and the cover layer 13 are made of the same material, they can be bonded together as a single unit. Because the interface between them is made of the same material, the bonding strength and the airtightness of the cover layer 13 are improved. In particular, when both materials are epoxy resins, heating to the range of 100°C to 200°C further promotes bonding, thus enhancing the bonding strength and the airtightness of the cover layer 13.

[0066] Next, the process for exposing the solder pads 9 used for the three-dimensional wiring will be described. For example... Figure 3 As shown in (c), the support layer 11 and the cover layer 13 are penetrated by means of laser irradiation or cutting, so that the solder pad 9 for three-dimensional wiring is exposed.

[0067] Furthermore, this process simultaneously creates a space to fill the three-dimensional wiring metal 15b used for internal wiring. Thus, in the process of exposing the three-dimensional wiring pads 9, at least two of the internal wiring pads 9b are exposed in the same space.

[0068] By exposing the solder pads 9 for the three-dimensional wiring, a space can be formed to fill the metal 15 for the three-dimensional wiring.

[0069] Since the process of exposing the solder pads 9 for three-dimensional wiring can easily cause physical damage to the solder pads 9 for three-dimensional wiring, a metal layer called Under Bump Metal (UBM) is usually formed in order to ensure wettability, connection strength and connection reliability with the metal 15 for three-dimensional wiring.

[0070] Representative UBM layer formation methods include electroless plating and electrolytic plating. In electroless plating, a wafer or substrate with exposed three-dimensional wiring pads 9 is immersed in an electroless plating bath with controlled temperature and concentration for an appropriate period of time for cleaning, thereby forming a UBM layer on the three-dimensional wiring pads 9.

[0071] In the electroplating process, UBM is formed using the following steps: A Ti (titanium) electroplating seed layer and a photoresist layer are formed on the entire surface of the wafer and substrate exposing the three-dimensional wiring pad 9. The photoresist layer is then patterned through an exposure and development process to expose the three-dimensional wiring pad 9 and the electroplating electrode.

[0072] The wafer and substrate, after the photoresist layer is patterned, are immersed in an electrolytic plating bath in which the temperature and concentration are controlled, and an appropriate current is passed through them for an appropriate period of time to form a UBM layer.

[0073] Afterwards, the photoresist is removed, the electroplating seed layer in areas other than the UBM layer is etched, and the surface is cleaned, thereby forming a UBM layer on the 3D wiring pad 9. Alternatively, if the UBM layer is formed by electroplating, a UBM layer may also be formed on the sidewall of the opening of the 3D wiring pad 9, thus increasing the bonding area between it and the 3D wiring metal 15, thereby improving connection strength and reliability.

[0074] The metals used in UBM layers, in electroless plating, are mainly layered structures of gold (Au), palladium (Pd), and nickel (Ni) from the surface, or layered structures of gold (Au) and nickel (Ni).

[0075] In electrolytic plating, the structure is similarly layered, starting from the surface and mainly consisting of gold (Au), nickel (Ni), and titanium (Ti) (seed layer), or a layered structure of gold (Au), nickel (Ni), copper (Cu), and titanium (Ti) (seed layer), or a layered structure of gold (Au), copper (Cu), and titanium (Ti) (seed layer).

[0076] Next, as Figure 3 As shown in (d), the three-dimensional wiring metal 15 is formed by filling solder paste HP with a metal mask MM. The metal composition of the solder paste is not limited and may contain lead or not.

[0077] The metal 15 used for the three-dimensional wiring is solder or an alloy containing solder. The solder paste can be, for example, an alloy based on Sn-Pb, Sn-Cu, Sn-Ag, Sn-Bi, Sn-In, or Sn-Sb. The content of solder powder and flux in the solder paste can be, for example, 5% to 95% by mass of solder powder and 5% to 95% by mass of flux. In the first embodiment, a solder paste containing approximately 90% by mass of solder powder is used.

[0078] The metal mask MM is, for example, a metal plate formed of a metal such as stainless steel. When using this metal mask MM to fill the three-dimensional wiring metal, the opening on the outer connection pad 9a of the surface acoustic wave device is larger than the opening on the inner wiring pad 9b of the surface acoustic wave device. In this embodiment, in the three-dimensional wiring metal 15, an opening with a diameter between 100 μm and 120 μm is formed, for example, at the location where the three-dimensional wiring metal 15a forms the outer connection. Furthermore, in the three-dimensional wiring metal 15, an opening with a diameter between 25 μm and 50 μm is formed, for example, at the location where the three-dimensional wiring metal 15b forms the inner wiring. Moreover, the thickness of the metal mask MM can be, for example, 50 μm.

[0079] In the three-dimensional wiring metal 15, the width of the three-dimensional wiring metal 15a used for external connections can be, for example, 50μm to 100μm. Furthermore, the three-dimensional wiring metal 15b used for internal wiring can be appropriately designed according to the desired wiring pattern. In this embodiment, the three-dimensional wiring metal 15b used for internal wiring is an internal wiring with a width of 60μm and a length of 200μm. The three-dimensional wiring metal 15b used for internal wiring electrically connects two internal wiring pads 9b.

[0080] Next, the metal mask MM is removed, reflow soldering is performed, flux is cleaned, and cross-sectioning is conducted to obtain the desired result. Figure 1 and Figure 2 The elastic surface wave device 1 is shown. Therefore, the three-dimensional wiring metal 15a for external connection formed on the external connection pad 9a is 50μm to 65μm higher than the surface of the cover layer 13. And, the three-dimensional wiring metal 15b for internal wiring formed on the internal wiring pad 9b is 14μm higher than the surface of the cover layer 13.

[0081] That is, the three-dimensional wiring metal 15a for external connections formed on the external connection pad 9a is higher than the three-dimensional wiring metal 15b for internal wiring formed on the internal wiring pad 9b. Therefore, although the three-dimensional wiring metal 15b for internal wiring is exposed on the mounting surface side, even after the elastic surface wave device 1 is mounted, the three-dimensional wiring metal 15b for internal wiring will not short-circuit with the wiring on the mounting substrate. Therefore, the three-dimensional wiring metal 15b for internal wiring of the elastic surface wave device 1 can be practically used as internal wiring.

[0082] Compared to chip-level packaging structures that use piezoelectric substrates bonded to a substrate, WLP-type flexible surface wave devices, which significantly limit the number of wiring layers, have significant technical implications by expanding wiring options without increasing the size of the piezoelectric substrate or the number of layers in the packaging structure.

[0083] Thus, the reason why the wiring options can be increased without increasing the size of the piezoelectric substrate or the number of packaging layers is that, through the manufacturing method of the present invention, internal wiring can be formed in the area of ​​the support layer 11 and the cover layer 13. Moreover, the three-dimensional wiring metal 15b used for internal wiring is also thicker than that of a typical wiring pattern, so it can be used as a low-impedance wiring.

[0084] Next, the functional components of the elastic surface wave device 1 will be described. Figure 4 This is a schematic top view of an elastic surface wave resonator.

[0085] like Figure 4 As shown, an IDT 50 for exciting elastic surface waves and a reflector 52 are formed on a piezoelectric substrate 30. The IDT 50 has a pair of opposing comb-shaped electrodes 50a. The comb-shaped electrodes 50a have several electrode fingers 50b and several busbars 50c connecting the electrode fingers 50b. The reflector 52 is disposed on both sides of the IDT 50.

[0086] The IDT 50 and reflector 52 are, for example, thin films with a thickness between 150 nm and 400 nm. The IDT 50 and reflector 52 may include other metals, such as titanium, palladium, silver, or suitable metals, or alloys containing the aforementioned metals, or may be formed by these alloys. The IDT 50 and reflector 52 may also be multilayer metal structures composed of several stacked metal layers.

[0087] Figure 5 This is a schematic diagram of the structure of a filter that can be used in the elastic surface wave device 1 of the present invention.

[0088] like Figure 5 As shown, an elastic surface wave resonator 53 composed of an IDT 50 and a reflector 52, and a first wiring pattern 54 are formed on the piezoelectric substrate 30.

[0089] The first wiring pattern 54 includes wiring that forms an input pad In, an output pad Out, and a ground pad GND. Furthermore, the first wiring pattern 54 is electrically connected to the surface wave resonator 53.

[0090] An insulator 56 is formed on the first wiring pattern 54. The insulator 56 may be, for example, made of polyimide. The film thickness of the insulator 56 may be, for example, 1000 nm.

[0091] A second wiring pattern 58 is formed on the insulator 56. The second wiring pattern 58 intersects the insulator 56 and the first wiring pattern 54 in a three-dimensional manner.

[0092] The surface wave resonator 53, the first wiring pattern 54, and the second wiring pattern 58 can be formed, for example, of suitable metals such as silver, aluminum, copper, titanium, palladium, or their alloys. Furthermore, these metal patterns, such as the first wiring pattern 54 and the second wiring pattern 58, can be, for example, multilayer metal structures composed of several stacked metal layers. The thickness of the surface wave resonator 53, the first wiring pattern 54, and the second wiring pattern 58 is, for example, between 150 nm and 400 nm.

[0093] Next, Embodiment 2 of the present invention will be described. Figure 6This is a diagram illustrating the manufacturing method of Embodiment 2 of the present invention.

[0094] In manufacturing the elastic surface wave device 1, firstly as follows: Figure 6 As shown in (a), an IDT electrode 25, a wiring pattern 27, and a three-dimensional wiring pad 29 are formed on the upper surface of the piezoelectric substrate 23. The top layer of the three-dimensional wiring pad 29 is formed with gold (Au) or the like to form a UBM layer.

[0095] Next, as Figure 6 As shown in (b), a support layer 211 is formed in the area other than the area where the IDT electrode 25 is formed and the area where the three-dimensional wiring pad 29 is formed.

[0096] Next, as Figure 6 As shown in (c), a film-like covering layer 213 is provided on the upper surface of the support layer 211, thereby bonding the support layer 211 with the covering layer 213. This allows the covering layer 213 to provide a sealed vibration space (cavity region 210) in the area where the IDT electrode 25 is formed.

[0097] Here, the cover layer 213 may be a pre-prepared membrane with several openings to expose the area where the three-dimensional wiring pads 29 are formed, or the openings may be formed after the cover layer 213 is placed on the support layer 211 to expose the three-dimensional wiring pads 29.

[0098] In Embodiment 2, since a UBM layer has already been formed on the surface of the 3D wiring pad 29, it is not necessary to form the UBM layer after forming the opening at the location of the 3D wiring pad 29 as shown in Embodiment 1. Therefore, the processing time can be reduced. In addition, in Embodiment 2, it has been described that a UBM layer is formed on the top layer of the 3D wiring pad 29 during the manufacturing process of the Surface Elastomer 1. However, if it is not necessary to form a UBM layer on the top layer of the 3D wiring pad 29 during the manufacturing process of the Surface Elastomer 1, an opening can be formed by forming the pattern of the support layer 211 and the cover layer 213 to expose the 3D wiring pad 29, and then a UBM layer can be formed on the 3D wiring pad 29 using the electroless plating method or electrolytic plating method shown in Embodiment 1.

[0099] In Example 2, since a UBM layer has already been formed on the surface of the solder pad 29 for three-dimensional wiring, the UBM layer formation process after the opening of the solder pad 29 for three-dimensional wiring, as in Example 1, is not required. Therefore, a shorter production cycle can be achieved.

[0100] Furthermore, in Embodiment 2, although the case where a UBM layer is formed on the top layer of the three-dimensional wiring pad 29 during the manufacturing process of the surface acoustic wave device 1 was described, in the case where a UBM layer is not formed on the top layer of the three-dimensional wiring pad 29 during the manufacturing process of the surface acoustic wave device 1, an opening is formed by the pattern formation of the support layer 211 and the cover layer 213 to expose the three-dimensional wiring pad 29. After that, a UBM layer can be formed on the three-dimensional wiring pad 29 using the electroless plating method or the electrolytic plating method shown in Embodiment 1.

[0101] Since the specific methods and details of the procedure described in Example 2 are the same as those in Example 1, as are the other processes and the structure of the elastic surface wave device 1, detailed descriptions are omitted.

[0102] According to the manufacturing method of the elastic surface wave device of the present invention described above, a WLP-type elastic surface wave device can be provided, which has a greater number of wiring layers and a higher degree of freedom in wiring design than the prior art, and has stable characteristics due to the low impedance of the grounding wiring.

[0103] It should be noted that, of course, the present invention is not limited to the embodiments described above, but also includes all embodiments that can achieve the purpose of the present invention.

[0104] Furthermore, while at least one embodiment has been described above, it should be understood that various changes, modifications, or improvements will readily conceive of by those skilled in the art. These changes, modifications, or improvements are also part of this disclosure and fall within the scope of the invention. It should be understood that the embodiments of the methods or apparatus described herein are not limited to the architecture and arrangement of the constituent components described above or illustrated in the accompanying drawings. Methods and apparatus can be installed or implemented in other embodiments. The embodiments described are for illustrative purposes only and are not intended to be limiting. Moreover, the descriptions or terms used herein are for illustrative purposes only and are not intended to be limiting. The use of "comprising," "possessing," "having," "including," and variations thereof herein means to include the items listed below, their equivalents, and additional items. The term "or," or any term used in the description of "or," can be interpreted as meaning one, more than one, or all of the descriptive terms. References to front, back, left, right, top, bottom, upper, lower, and horizontal and vertical are for convenience of description and are not intended to limit the position and spatial configuration of any constituent component in the invention. Therefore, the above description and accompanying drawings are merely illustrative.

Claims

1. A method for manufacturing an elastic surface wave device, characterized in that: The method for manufacturing the elastic surface wave device includes: The process of forming a metal pattern: forming a metal pattern containing an IDT electrode that excites elastic surface waves and several three-dimensional wiring pads on a piezoelectric substrate; The process of forming the support layer: A support layer is formed in the area outside the region where the IDT electrode is formed; The process of forming the capping layer: A capping layer is formed by covering the IDT electrode on the support layer with a gap; Exposure process: Exposing the solder pads for the aforementioned three-dimensional wiring; A UBM layer is formed on the solder pads for the three-dimensional wiring. Process for filling metal for three-dimensional wiring: Using a mask, the space formed in the exposure process that exposes the plurality of three-dimensional wiring pads is filled with metal for three-dimensional wiring, and the opening of the mask on the outer connection pad of the elastic surface wave device is larger than the opening on the inner wiring pad of the elastic surface wave device, and the opening on the inner wiring pad is smaller than the opening of the cover layer formed on the pad for inner wiring after the exposure process.

2. A method for manufacturing an elastic surface wave device, characterized in that: The method for manufacturing the elastic surface wave device includes: The process of forming a metal pattern: forming a metal pattern containing an IDT electrode that excites elastic surface waves and several three-dimensional wiring pads on a piezoelectric substrate; The process of forming a support layer: A support layer is formed in a region other than at least a portion of the region where the IDT electrode is formed and the region where the three-dimensional wiring pad is formed; The process of forming the capping layer: A capping layer is formed on the support layer by covering at least a portion of the area of ​​the IDT electrode and the three-dimensional wiring pad with a gap; A UBM layer is formed on the solder pads for the three-dimensional wiring. The process of filling the metal for three-dimensional wiring: using a mask, the metal for three-dimensional wiring is filled in the space partially surrounded by the plurality of three-dimensional wiring pads, the support layer and the cover layer, wherein the opening of the mask on the outer connection pad of the elastic surface wave device is larger than the opening on the inner wiring pad of the elastic surface wave device, and the opening on the inner wiring pad is smaller than the opening of the cover layer formed on the inner wiring pad.

3. The method for manufacturing the elastic surface wave device according to claim 1 or claim 2, characterized in that: In the process of forming the support layer, the support layer surrounds the IDT electrode.

4. The method for manufacturing the elastic surface wave device according to claim 1 or claim 2, characterized in that: During the process of forming the capping layer, the IDT electrode is enclosed by the support layer and the capping layer.

5. The method for manufacturing the elastic surface wave device according to claim 1 or claim 2, characterized in that: The metal used for the three-dimensional wiring is solder or an alloy containing solder.

6. The method for manufacturing the elastic surface wave device according to claim 1, characterized in that: In the exposure process, at least two of the internal wiring pads are exposed in the same space.

7. The method for manufacturing the elastic surface wave device according to claim 1 or claim 2, characterized in that: In the process of filling the three-dimensional wiring metal, at least two of the internal wiring pads are electrically connected by the three-dimensional wiring metal.

8. The method for manufacturing the elastic surface wave device according to claim 1 or claim 2, characterized in that: In the process of filling the three-dimensional wiring metal, the three-dimensional wiring metal formed on the external connection pad is higher than the three-dimensional wiring metal formed on the internal wiring pad.

9. The method for manufacturing the elastic surface wave device according to claim 1 or 2, characterized in that: The diameter of the opening on the external connection pad is between 100μm and 120μm, and the diameter of the opening on the internal wiring pad is between 25μm and 50μm.

10. The method for manufacturing the elastic surface wave device according to claim 1 or 2, characterized in that: The solder pads for the three-dimensional wiring are made of a conductive material selected from aluminum alloys or elemental aluminum.

Images