Elastic wave device and elastic wave module

Abstract

The utility model relates to an elastic wave device and an elastic wave module, the elastic wave device comprises a packaging substrate, a supporting part, an IDT electrode, a piezoelectric substrate, an electrode pad and a conductive metal, the packaging substrate is arranged on the supporting part; the support part surrounds the IDT electrode and is formed on the main surface of the piezoelectric substrate. The supporting part is provided with a through hole; the IDT electrode is formed on the main surface of the piezoelectric substrate. The main surface of the piezoelectric substrate is provided with a first groove, and the first groove is formed below the through hole and is communicated with the through hole; the electrode bonding pad is formed at the bottom of the first groove and is connected with the conductive metal; and the conductive metal is arranged in the first groove and the through hole and is used for connecting the electrode bonding pad and the packaging substrate. Through the elastic wave device and the elastic wave module, the problem that the elastic wave device cannot be further miniaturized due to the fact that an electrode bonding pad and conductive metal of a traditional WLP packaging structure need to be arranged in a through hole of a supporting part is solved, and the size of the elastic wave device is effectively reduced.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor packaging technology, and in particular to an elastic wave device and an elastic wave module. Background Technology

[0002] With the rapid development of mobile communication technology, especially the widespread adoption of 5G and the Internet of Things (IoT), the demand for high-frequency, high-precision, and high-reliability elastic wave devices is increasing. To meet these demands, it is necessary to continuously explore new materials and manufacturing processes to achieve miniaturization of elastic wave devices. Miniaturization can not only reduce the size and weight of devices and improve integration, but also reduce power consumption and improve the overall system performance.

[0003] Traditional wafer-level packaging (WLP) structures typically include a packaging substrate, a roof, a support, an IDT electrode, and a piezoelectric substrate. The roof, support, and device chip form a sealed internal space to ensure the frequency stability and quality factor of the elastic wave device and to prevent molding compound from entering the internal space. This structure requires multiple photolithography processes to form. The support has through-holes containing electrode pads and conductive metal for electrically connecting the packaging substrate to the IDT electrode. Therefore, because the electrode pads and conductive metal in traditional WLP packaging structures must be located within the through-holes of the support, the height of the support cannot be further reduced, thus hindering further miniaturization of the elastic wave device.

[0004] There is currently no suitable solution to the problem that the electrode pads and conductive metal of the traditional WLP package structure need to be placed in the through holes of the support, which prevents the elastic wave device from being further miniaturized. Utility Model Content

[0005] This invention provides an elastic wave device and an elastic wave module to solve the problem that the electrode pads and conductive metal of the traditional WLP package structure need to be placed in the through holes of the support, which prevents the elastic wave device from being further miniaturized.

[0006] In the first aspect, this embodiment provides an elastic wave device, including a packaging substrate, a support portion, an IDT electrode, a piezoelectric substrate, electrode pads, and a conductive metal, wherein the packaging substrate is disposed on the support portion;

[0007] The support portion surrounds the IDT electrode and is formed on the main surface of the piezoelectric substrate; the support portion has through holes;

[0008] The IDT electrode is formed on the main surface of the piezoelectric substrate;

[0009] The main surface of the piezoelectric substrate has a first groove formed below the through hole and communicating with the through hole;

[0010] The electrode pad is formed at the bottom of the first groove and is connected to the conductive metal;

[0011] The conductive metal is disposed inside the first groove and the through hole, and is used to connect the electrode pad and the packaging substrate.

[0012] In some embodiments, the elastic wave device further includes a protective layer covering the surface of the IDT electrode.

[0013] In some of these embodiments, the protective layer is made of silicon oxide.

[0014] In some of these embodiments, the height of the support portion is 50 μm to 100 μm.

[0015] In some embodiments, the side of the packaging substrate that engages with the support portion has a bump pad;

[0016] The bump pad is located inside the through hole and is connected to the conductive metal.

[0017] In some embodiments, the sum of the thicknesses of the conductive metal and the electrode pads is less than the sum of the height of the through hole and the depth of the first groove;

[0018] The sum of the thicknesses of the bump pad, the conductive metal, and the electrode pad is greater than the sum of the height of the through hole and the depth of the first groove.

[0019] In some embodiments, the main surface of the piezoelectric substrate further has a second groove, which is surrounded by the first groove;

[0020] The IDT electrode is disposed within the second groove.

[0021] In some of these embodiments, the conductive metal includes metal bumps, columnar metal, and a seed layer;

[0022] The metal bump is formed above the columnar metal; the seed layer is formed at the bottom of the columnar metal and on the inner wall of the first groove.

[0023] In some of the embodiments, the support portion is made of an insulating material.

[0024] Secondly, this utility model provides an elastic wave module, which includes a plurality of elastic wave devices as described in the first aspect above.

[0025] Compared with related technologies, this embodiment provides an elastic wave device and module, including a packaging substrate, a support portion, an IDT electrode, a piezoelectric substrate, electrode pads, and conductive metal. The packaging substrate is disposed on the support portion; the support portion surrounds the IDT electrode and is formed on the main surface of the piezoelectric substrate; the support portion has a through hole; the IDT electrode is formed on the main surface of the piezoelectric substrate; the main surface of the piezoelectric substrate has a first groove formed below the through hole and communicating with the through hole; the electrode pad is formed at the bottom of the first groove and connected to the conductive metal; the conductive metal is disposed inside the first groove and the through hole for connecting the electrode pad and the packaging substrate. This elastic wave device solves the problem that the electrode pads and conductive metal of the traditional WLP packaging structure need to be disposed in the through hole of the support portion, which prevents further miniaturization of the elastic wave device, effectively reducing the size of the elastic wave device.

[0026] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0027] The accompanying drawings, which are provided to further understand this application and constitute a part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0028] Figure 1 This is a cross-sectional view of the elastic wave device according to the first embodiment of this application;

[0029] Figure 2 This is a cross-sectional view of the elastic wave device according to the second embodiment of this application;

[0030] Figure 3 This is a cross-sectional view of the elastic wave device according to the third embodiment of this application;

[0031] Figure 4 This is a cross-sectional view of the elastic wave device according to the fourth embodiment of this application;

[0032] Figure 5 This is a cross-sectional view of the elastic wave device according to the fifth embodiment of this application;

[0033] Figure 6 This is a cross-sectional view of the elastic wave device according to a preferred embodiment of this application;

[0034] Figures 7-12 This is a flowchart illustrating the fabrication method of the elastic wave device of this application.

[0035] In the figure: 100, packaging substrate; 110, bump pad; 200, support portion; 300, IDT electrode; 400, piezoelectric substrate; 400a, main surface of piezoelectric substrate; 500, electrode pad; 600, conductive metal; 610, metal bump; 620, columnar metal; 630, seed layer; 700, protective layer. Detailed Implementation

[0036] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0037] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these” used in this application do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to these processes, methods, products, or devices. Words such as “connected,” “linked,” and “coupled” used in this application are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. Normally, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," "third," etc., used in this application are merely to distinguish similar objects and do not represent a specific order of objects.

[0038] The following is based on Figures 1 to 12 The elastic wave device of this application will be described.

[0039] The embodiments are described below with reference to the accompanying drawings. In each drawing, the same or corresponding parts are labeled with the same reference numerals. For parts that are described repeatedly, they will be appropriately simplified or omitted.

[0040] Figure 1 This is a cross-sectional view of the elastic wave device according to the first embodiment of this application, as shown below. Figure 1As shown, the elastic wave device includes a packaging substrate 100, a support portion 200, an IDT electrode 300, a piezoelectric substrate 400, an electrode pad 500, and a conductive metal 600. The packaging substrate 100 is disposed on the support portion 200. The support portion 200 surrounds the IDT electrode 300 and is formed on the main surface 400a of the piezoelectric substrate 400. The support portion 200 has a through hole. The IDT electrode 300 is formed on the main surface 400a of the piezoelectric substrate 400. The main surface 400a of the piezoelectric substrate 400 has a first groove, which is formed below the through hole of the support portion 200 and communicates with the through hole. The electrode pad 500 is formed at the bottom of the first groove and is connected to the conductive metal 600. The conductive metal 600 is disposed inside the first groove and the through hole for connecting the electrode pad 500 and the packaging substrate 100.

[0041] Specifically, the encapsulation substrate 100, the support portion 200, and the piezoelectric substrate 400 form a sealed space, within which the IDT electrode 300 is located. This sealed space effectively reduces the leakage of elastic wave energy, thereby ensuring the Q value (quality factor) of the elastic wave device. The piezoelectric substrate 400 is made of lithium tantalate or lithium niobate, with a thickness of 100 μm to 450 μm. The IDT electrode 300 is formed on the main surface 400a of the piezoelectric substrate 400 and consists of electrode pairs. Each electrode pair connects multiple electrode fingers to each other at one end by a busbar. These multiple electrode fingers are arranged parallel to each other in a manner that crosses the propagation direction of the elastic wave. The electrode pads are made of at least one of titanium, aluminum, copper, gold, nickel, and chromium, with a thickness of 150 nm to 400 nm. The electrode pads 500 are made of at least one of aluminum, copper, nickel, gold, and platinum. The packaging substrate 100 is primarily made of resin and contains electronic components. One side of the packaging substrate 100 is bonded to one side of the support portion 200, and the other side has external connection terminals (not shown in the figure). Electrical connection between the elastic wave device and an external circuit is achieved through the external connection terminals on the packaging substrate 100 and the aforementioned electronic components. The through-hole diameter of the support portion 200 is 3μm to 46μm. The conductive metal 600 in the through-hole and the first groove is made of at least one of copper, nickel, and tin-silver alloy. The depth of the first groove is 80μm to 150μm, more preferably 100μm to 130μm. In this embodiment, by placing the electrode pads 500 and part of the conductive metal 600 within the first groove, the height of the support portion 200 can be reduced. It should be noted that the piezoelectric substrate 400 also includes a wiring area (not shown in the figure) for electrically connecting the electrode pads 500 to the IDT electrode 300.

[0042] Compared with the traditional WLP packaging structure, the above-mentioned elastic wave device reduces the height of the support portion 200 by setting the electrode pads 500 and part of the conductive metal 600 in the first groove, thereby realizing the miniaturization of the elastic wave device.

[0043] In some embodiments, the elastic wave device further includes a protective layer covering the surface of the IDT electrode.

[0044] Specifically, Figure 2 This is a cross-sectional view of the elastic wave device according to the second embodiment of this application, as shown below. Figure 2 As shown, the protective layer 700 is composed of materials such as silicon oxide, silicon nitride, and silicon carbide. The protective layer 700 is formed through chemical vapor deposition and dry etching processes to prevent oxidation of the IDT electrode 300, thereby improving the reliability and lifespan of the elastic traveling wave device. Furthermore, the attenuation of the elastic wave can be controlled by adjusting the thickness of the protective layer 700, thus optimizing the frequency characteristics of the elastic traveling wave device.

[0045] In some of these embodiments, the protective layer 700 is made of silicon oxide.

[0046] Specifically, silicon oxide has a low coefficient of thermal expansion. When the protective layer 700 is made of silicon oxide, stress caused by temperature changes can be reduced, thereby improving the temperature stability of the elastic device.

[0047] In some of these embodiments, the height of the support portion 200 is 50 μm to 100 μm.

[0048] Specifically, in this embodiment, the height of the support portion 200 is 50μm~100μm, and the preferred height is 58μm~78μm. Since the through hole of the conventional support portion 200 includes electrode pads 500 and conductive metal 600, and in order to ensure the volume of the sealed space, this embodiment sets the electrode pads 500 and part of the conductive metal 600 in the first groove, so that the height of the elastic wave device has room to decrease.

[0049] In some embodiments, the package substrate 100 has a bump pad 110 on the side that engages with the support portion 20; the bump pad 110 is located within a through-hole and is connected to the conductive metal 600.

[0050] Specifically, Figure 3 This is a cross-sectional view of the elastic wave device according to the third embodiment of this application, as shown below. Figure 3 As shown, the bump pad 110 is bonded to the conductive metal 600 to achieve electrical connection between the package substrate 100, the conductive metal 600 and the electrode pad 500. The length L2 of the bump pad 110 is smaller than the aperture L1 of the through hole, so that the bump pad is located inside the through hole to ensure the sealing of the package substrate and the support portion.

[0051] In some of these embodiments, such as Figure 3 As shown, the sum of the thickness t2 of the conductive metal 600 and the thickness t1 of the electrode pad 500 is less than the sum of the height h1 of the through hole and the depth d1 of the first groove, to prevent the conductive metal from overflowing from the through hole; the sum of the thickness t3 of the bump pad, the thickness t2 of the conductive metal, and the thickness t1 of the electrode pad is greater than the sum of the height h1 of the through hole and the depth d1 of the first groove, because the bump pad is located inside the through hole, and because the sum of the thicknesses of the bump pad, the conductive metal, and the electrode pad is greater than the height h1 of the through hole...

[0052] The sum of the depth h1 and the depth d1 of the first groove melts the conductive metal 600 during the reflow soldering process, causing the bump pad 110 to be partially embedded in the conductive metal 600. This ensures that the bump pad 110 is in full contact with the conductive metal 600 in the through hole, thereby ensuring the reliability of the electrical connection between the bump pad 110 and the conductive metal 600.

[0053] In some embodiments, the main surface 400a of the piezoelectric substrate also has a second groove surrounded by the first groove; the IDT electrode 300 is disposed in the second groove.

[0054] Specifically, Figure 4 This is a cross-sectional view of the elastic wave device according to the fourth embodiment of this application, as shown below. Figure 4 As shown, the depth d2 of the second groove is 0μm~200μm, preferably 10μm~100μm. While ensuring that the volume of the sealed space remains unchanged, the height of the support 200 can be further reduced by setting the second groove, thereby achieving further miniaturization of the elastic wave device.

[0055] Figure 5 This is a cross-sectional view of the elastic wave device according to the fifth embodiment of this application, as shown below. Figure 5 As shown, the conductive metal 600 includes a metal bump 610, a columnar metal 620, and a seed layer 630; the metal bump 610 is formed above the columnar metal 620; the seed layer 630 is formed at the bottom of the columnar metal 620 and on the inner wall of the first groove.

[0056] Specifically, the columnar metal 620 is connected to the bump pad 110 on one side of the packaging substrate 100 via metal bumps 610. The columnar metal 620 enables electrical connection between the electrode pad 500 and the electronic components in the packaging substrate 100. The columnar metal 620 is made of conductive materials such as aluminum, copper, silver, or gold. A seed layer 630 is formed at the bottom of the columnar metal 620 and on the inner wall of the through-hole. Its constituent materials include at least one of titanium and copper. This seed layer improves the adhesion between the conductive metal 600 and the electrode pad 500 and acts as a protective layer to prevent corrosion of the electrode pad 500, thereby ensuring the reliability of the elastic wave device.

[0057] In some of these embodiments, the support portion 200 is made of an insulating material.

[0058] Specifically, the supporting part 200 can be made of insulating materials with stable chemical properties and good thermal stability, such as silicon oxide, silicon nitride, or PI glue, to prevent the molding material from seeping into the sealed space during the encapsulation of the elastic wave device, thereby improving the sealing performance of the sealed space and ensuring the reliability of the elastic wave device.

[0059] The elastic wave device of this application will be described below through preferred embodiments.

[0060] Figure 6 This is a cross-sectional view of the elastic wave device according to a preferred embodiment of this application, as shown below. Figure 6 As shown, the elastic wave device of this preferred embodiment includes a packaging substrate 100, a support portion 200, an IDT electrode 300, a piezoelectric substrate 400, an electrode pad 500, and a conductive metal 600. The packaging substrate 100 is disposed on the support portion 200. The support portion 200 surrounds the IDT electrode 300 and is formed on the main surface 400a of the piezoelectric substrate 400. The support portion 200 has a through hole. The IDT electrode 300 is formed on the main surface 400a of the piezoelectric substrate 400. The main surface 400a of the piezoelectric substrate 400 has a first groove, which is formed below the through hole and communicates with the through hole. The electrode pad 500 is formed at the bottom of the first groove and is connected to the conductive metal 600. The conductive metal 600 is disposed inside the first groove and the through hole for connecting the electrode pad 500 and the packaging substrate 100. The height of the support portion 200 is 50μm~100μm, and its constituent material is an insulating material.

[0061] The elastic wave device also includes a protective layer 700, which covers the surface of the IDT electrode 300 and is made of silicon oxide. A bump pad 110 is also provided on the bonding surface between the packaging substrate 100 and the support portion 200; the bump pad 110 is located within a through-hole and connected to the conductive metal 600. The sum of the thicknesses of the conductive metal 600 and the electrode pad 500 is less than the sum of the height of the through-hole and the depth of the first groove; the sum of the thicknesses of the bump pad 110, the conductive metal 600, and the electrode pad 500 is greater than the sum of the height of the through-hole and the depth of the first groove. The main surface 400a of the piezoelectric substrate 400 also has a second groove, which is surrounded by the first groove; the IDT electrode 300 is disposed within the second groove. The conductive metal 600 includes metal bumps 610, columnar metal 620, and seed layer 630; the metal bumps 610 are stacked on top of the columnar metal 620; the seed layer 630 is formed at the bottom of the columnar metal 620 and on the inner wall of the first groove.

[0062] The elastic wave device of this preferred embodiment reduces the height of the support by placing the electrode pads and a portion of the conductive metal in the first groove. This solves the problem that the electrode pads and conductive metal in the traditional WLP package structure need to be placed in the through holes of the support, which prevents the elastic wave device from being further miniaturized. This achieves the miniaturization of the elastic wave device. Furthermore, by setting the second groove, the height of the support can be further reduced, thereby achieving further miniaturization of the elastic wave device.

[0063] Figures 7 to 12 This is a schematic flowchart of the fabrication method of the elastic wave device according to the preferred embodiment above. The specific steps are as follows:

[0064] S1, as Figure 7 As shown, a first photoresist pattern is formed through coating, exposure, and development processes. Based on the first photoresist pattern, a dry etching process is performed on the piezoelectric substrate 400 to form a first groove and a second groove.

[0065] S2, as Figure 8 As shown, the second photoresist pattern is formed through coating, exposure, and development processes, based on...

[0066] The second photoresist pattern is deposited on the main surface 400a of the piezoelectric substrate 400 by metal evaporation, and an IDT electrode 300 is formed in the second groove.

[0067] S3, as Figure 9 As shown, a protective layer 700 is applied to the surface of the IDT electrode 300 by chemical vapor deposition and dry etching processes to prevent the IDT electrode 300 from being oxidized.

[0068] S4, such as Figure 10As shown, a third photoresist pattern is formed by coating, exposure, and development. Based on the third photoresist pattern, metal is deposited in the first groove of the piezoelectric substrate 400 to form an electrode pad 500.

[0069] S5, such as Figure 11 As shown, a seed layer 630, columnar metal 620, and metal bumps 610 are formed sequentially by electroplating.

[0070] S6, such as Figure 12 As shown, the support portion is formed by coating, exposure, and development, and corona treatment is performed on the surface of the support portion 200 to increase the adhesion of the support portion 200 surface. Then, through processes such as reflow soldering, grinding and cutting, the bump pads 110 on the packaging substrate 100 are connected to the metal bumps 610, so that one side of the packaging substrate 100 is joined to one side of the support portion 200, forming the elastic wave device of this preferred embodiment.

[0071] The elastic wave device obtained through the above steps solves the problem that the electrode pads and conductive metal of the traditional WLP packaging structure need to be placed in the through holes of the support, which prevents the elastic wave device from being further miniaturized, and effectively reduces the size of the elastic wave device.

[0072] This invention also provides an elastic wave module, comprising multiple elastic wave devices and a sealing part, which seals the elastic wave devices and other components. This elastic wave module enables the transmission and reception of signals in a wireless communication system.

[0073] The expressions and terms used in this utility model are for illustrative purposes only and should not be considered limiting. The use of "comprising," "possessing," "having," "including," and variations thereof as used herein means to include the following items, their equivalents, and additional items.

[0074] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or independent of other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0075] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications, alterations, and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. An elastic wave device comprising a package substrate, a support portion, an IDT electrode, a piezoelectric substrate, an electrode pad, and a conductive metal, wherein: the package substrate is disposed on the support portion; the support portion surrounds the IDT electrode and is formed on a main surface of the piezoelectric substrate; the support portion has a through-hole; the IDT electrode is formed on the main surface of the piezoelectric substrate; the main surface of the piezoelectric substrate has a first recess formed below the through-hole and penetrating the through-hole; the electrode pad is formed on a bottom of the first recess and is connected to the conductive metal; and the conductive metal is disposed inside the first recess and the through-hole to connect the electrode pad and the package substrate. The elastic wave device further comprises a protective layer covering a surface of the IDT electrode. The protective layer is made of silicon oxide. The support portion has a height of 50 μm to 100 μm. One surface of the package substrate, which is bonded to the support portion, has a bump pad. The bump pad is located inside the through-hole and is connected to the conductive metal.

6. The elastic wave device according to claim 5, wherein: a sum of thicknesses of the conductive metal and the electrode pad is smaller than a sum of a height of the through-hole and a depth of the first recess; and a sum of thicknesses of the bump pad, the conductive metal, and the electrode pad is larger than the sum of the height of the through-hole and the depth of the first recess.

2. The elastic wave device according to claim 1, characterized by, The main surface of the piezoelectric substrate further has a second recess surrounded by the first recess.

3. The elastic wave device according to claim 2, characterized by, The IDT electrode is disposed inside the second recess.

4. The elastic wave device according to claim 1, characterized by, The conductive metal includes a metal bump, a columnar metal, and a seed layer.

5. The elastic wave device according to claim 1, characterized in that, The metal bump is formed above the columnar metal; and the seed layer is formed on a bottom of the columnar metal and an inner wall of the first recess. The support portion is made of an insulating material.

10. An elastic wave module comprising the elastic wave device according to any one of claims 1 to 9. ​ ​ 7. The elastic wave device according to claim 1, characterized in that, ​ ​ 8. The elastic wave device of claim 1, wherein, ​ ​ 9. The elastic wave device of claim 1, wherein, ​ ​

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