SAW filter and electronic device

Abstract

The utility model provides an SAW filter and an electronic device. Wherein the supporting wall body in the SAW filter comprises a plurality of first supporting pieces and a plurality of second supporting pieces, at least part of the first supporting pieces surround each interdigital transducer to form a plurality of cavities, and the second supporting pieces are located in part of the cavities. The second supporting piece is located on the substrate or the first supporting piece, and the height of the top face of the second supporting piece is larger than that of the top face of the first supporting piece, so that the heights of the top faces of the supporting walls are different, and then the cover plate covering the top faces of the supporting walls can form a curved surface shape. On the basis, the cover plate with the curved surface morphology can decompose the pressure generated during WLP packaging into a vertical component force and a horizontal component force, so that the vertical acting force borne by the cover plate and the supporting wall body is reduced, the collapse problem of the cover plate is relieved, and the device performance is improved.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing technology, and in particular to a SAW filter and electronic device. Background Technology

[0002] Surface acoustic wave (SAW) filters are commonly used filter chips in many electronic devices with communication functions. Please refer to... Figure 1 The SAW filter mainly consists of a piezoelectric substrate 100 and interdigital transducers (IDTs) 101. Based on the piezoelectric effect, it utilizes the interconversion of electrical and acoustic signals to achieve filtering. The interdigital transducers 101 are highly sensitive to environmental conditions. When pollutants or air disturbances are present in the environment, the interdigital transducers 101 will be interfered with, causing a shift in the filtering frequency band and affecting product performance. Therefore, in the SAW filter, multiple sealed cavities C are formed by supporting walls 102 and cover plates 103, and the interdigital transducers 101 are located within these sealed cavities C to ensure that the interdigital transducers 101 operate in a relatively stable environment.

[0003] However, as Figure 2 As shown, during the packaging of the SAW filter using wafer-level package (WLP) technology, the cover plate 103 is subjected to downward packaging pressure. Due to the limited support capacity of the existing support wall 102 for the cover plate 103, the top support of the sealing cavity C is relatively weak. Especially within the large-capacity sealing cavity C, the cover plate 103 is highly susceptible to collapse under packaging pressure, leading to deformation of the sealing cavity C. This is detrimental to the environmental stability of the interdigital transducer 101 and may even damage the interdigital transducer 101, severely affecting the product performance of the SAW filter.

[0004] Therefore, a new SAW filter structure is urgently needed to solve the above-mentioned technical problems. Utility Model Content

[0005] The purpose of this invention is to provide a SAW filter and electronic device to solve the technical problem of how to avoid the collapse of the cover plate of the SAW filter during the packaging process.

[0006] To solve the above-mentioned technical problems, this utility model provides a SAW filter, comprising:

[0007] A substrate on which multiple interdigital transducers are formed;

[0008] The support wall comprises a plurality of first support members and a plurality of second support members; the first support members are located on the substrate and at least some of the first support members surround the plurality of interdigital transducers to form a plurality of cavities; the plurality of second support members are located in some of the cavities; and

[0009] The plurality of second support members are located on the substrate and have a height greater than that of the first support members in the vertical direction; and / or, some of the first support members are located in some of the cavities and the plurality of second support members are located on the top surface of the first support members in the cavities and extend at least in the vertical direction;

[0010] A cover plate covers the top surface of the support wall and is connected to some of the first support members and the plurality of second support members surrounding the cavities to seal the plurality of cavities.

[0011] Optionally, in the SAW filter, the plurality of cavities comprise first cavities and second cavities; the first cavities contain the interdigital transducers; the second cavities contain at least the interdigital transducers and the second support members, and the second support members are located at least in the central region of the corresponding second cavities.

[0012] Optionally, in the SAW filter, the second cavities also contain the first support members, and the top surface of the first support members is connected to the plurality of second support members.

[0013] Optionally, in the SAW filter, in the second cavities, the second support members extend in a direction perpendicular to the top surface of the first support members.

[0014] Optionally, in the SAW filter, in the second cavities, the second support members extend in a direction perpendicular and parallel to the top surface of the first support members, so that in the direction parallel to the top surface of the first support members, the width of the second support members is greater than that of the first support members.

[0015] Optionally, in the SAW filter, the second cavities also contain support pads, the support pads are located on the substrate and are connected to the first support members or the second support members.

[0016] Optionally, in the SAW filter, the cover plate has a curved structure; some of the cover plate covering the top surface of the first cavities has a planar shape; some of the cover plate covering the top surface of the second cavities has an arched shape.

[0017] Optionally, in the SAW filter, the second support abuts against the arch of the arched portion of the cover plate and / or the central region where the arch is located.

[0018] Optionally, in the SAW filter, the SAW filter further includes: multiple metal pads, multiple metal pillars, and multiple metal balls; the metal pads, metal pillars, and metal balls are one-to-one corresponding and connected sequentially; wherein,

[0019] The metal pad is located on the substrate and is in contact with the bottom surface of the portion of the first support member surrounding the cavity; the two opposing surfaces of the metal pillar are respectively in contact with the corresponding metal pad and the metal ball, and the metal pillar penetrates the corresponding first support member and the cover plate located on the first support member.

[0020] Based on the same concept, this utility model provides an electronic device, including the aforementioned SAW filter.

[0021] In summary, this utility model provides a SAW filter and electronic device. Compared to the prior art, the support wall in the SAW filter includes multiple first support members and several second support members, with at least some of the first support members surrounding each interdigital transducer to form multiple cavities; the second support members are located within some of the cavities. The second support members are located on the substrate or on the first support members, and the top surface height of the second support member is higher than that of the first support member, resulting in a varying top surface height of the support wall. Consequently, the cover plate covering the top surface of the support wall will form a curved surface. The curved surface of the cover plate can decompose the pressure generated during WLP packaging into vertical and horizontal components, thereby reducing the vertical force on the cover plate and the support wall, which helps alleviate the collapse problem of the cover plate. Furthermore, the second support member can extend in a direction parallel to the top surface of the first support member to increase the contact area between the support wall and the cover plate, further promote the decomposition of WLP packaging pressure, improve the support effect of the support wall on the cover plate, effectively alleviate the collapse problem of the cover plate, protect the cavity and the interdigital transducer, and improve device performance. Attached Figure Description

[0022] Those skilled in the art will understand that the accompanying drawings are provided to better understand the present invention and do not constitute any limitation on the scope of the present invention.

[0023] Figure 1 This is a schematic diagram of the structure of a SAW filter in the prior art.

[0024] Figure 2This is a schematic diagram of the collapse of the top cover plate of a SAW filter in the prior art.

[0025] Figure 3 This is a top view schematic diagram of the SAW filter in the first and second examples of this utility model.

[0026] Figure 4 This is an embodiment of the present utility model. Figure 3 A schematic diagram of the cross section A-A' in the SAW filter of the first example shown.

[0027] Figure 5 This is an embodiment of the present utility model. Figure 3 A schematic diagram of the cross section A-A' in the SAW filter of the second example shown.

[0028] Figure 6 This is a top view schematic diagram of the SAW filter in the third and fourth examples of this utility model.

[0029] Figure 7 This is an embodiment of the present utility model. Figure 6 A schematic diagram of the B-B' cross section in the SAW filter of the third example shown.

[0030] Figure 8 This is a cross-sectional schematic diagram of the SAW filter in the third example of this utility model, in which two first support members are disposed in the second cavity.

[0031] Figure 9 This is an embodiment of the present utility model. Figure 6 A schematic diagram of the B-B' cross section in the SAW filter of the fourth example shown.

[0032] Figures 10-17 This is a schematic diagram of the structure corresponding to each fabrication step of the first SAW filter in this embodiment of the present invention.

[0033] Figures 18-27 This is a schematic diagram of the structure corresponding to each preparation step of the second type of SAW filter in this embodiment of the present invention.

[0034] And, in the attached image:

[0035] 100 - Substrate; 101 - Interdigital transducer; 102 - Support wall; 103 - Cover plate;

[0036] 200-Substrate; 201-Interdigital transducer; 202-Metal pad; 203-First support material layer; 203a-First support member; 204-Second support material layer; 204a-Second support member; 205-Cover plate; 206-Metal pillar; 207-Metal ball; 208-Support pad;

[0037] C - Sealed cavity; S1 - First cavity; S2 - Second cavity; M1 - First photomask; M2 - Second photomask; M3 - Third photomask; M4 - Fourth photomask; M5 - Fifth photomask; T - Through hole. Detailed Implementation

[0038] To make the objectives, advantages, and features of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, only used to facilitate and clearly illustrate the purpose of the embodiments of this utility model. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different figures may have different focuses and sometimes use different scales. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate the logical or sequential relationships between the various components, elements, steps, etc. Also, in this specification, the X-axis, Y-axis, and Z-axis directions are three mutually perpendicular directions in three-dimensional space, with the vertical direction referring to the Z-axis direction and the horizontal direction referring to the X-axis and / or Y-axis directions.

[0039] Please see Figure 3 and Figure 4 This embodiment provides a SAW filter, including: a substrate 200 on which a plurality of interdigital transducers 201 are formed; a support wall including a plurality of first support members 203a and a plurality of second support members 204a; the first support members 203a are located on the substrate 200, and at least a portion of the first support members 203a surround the plurality of interdigital transducers 201 to form a plurality of cavities; the plurality of second support members 204a are located within a portion of the cavities; and the plurality of second support members 204a Located on the substrate 200, and with a vertical height greater than the height of the first support 203a; and / or, a portion of the first support 203a is located within a portion of the cavity, and a plurality of second supports 204a are located on the top surface of the first support 203a within the cavity, and extend at least vertically; a cover plate 205 covers the top surface of the support wall and is in contact with the portion of the first support 203a and the plurality of second supports 204a surrounding the cavity to seal the plurality of cavities.

[0040] Based on this, the SAW filter provided in this embodiment, by setting the second support member 204a to make the top surface of the support wall have different heights, will cause the cover plate 205 covering the top surface of the support wall to form a curved shape. The cover plate 205 with a curved shape can decompose the pressure generated during WLP encapsulation into vertical and horizontal components, effectively alleviating the vertical force on the cover plate 205 and the support wall, and helping to alleviate the collapse problem of the cover plate 205.

[0041] The following is in conjunction with the appendix Figures 3 to 27 This embodiment provides a detailed description of the SAW filter.

[0042] Please continue reading. Figure 3 and Figure 4 The SAW filter provided in this embodiment includes a substrate 200, a support wall, and a cover plate 205. The substrate 200 is a piezoelectric substrate exhibiting the piezoelectric effect. The support wall and cover plate 205 are disposed on the substrate 200 and can form multiple sealed cavities on the substrate 200 to provide a stable operating environment for the interdigital transducers 201 on the substrate 200.

[0043] Specifically, the substrate 200 is made of materials including, but not limited to, lithium tantalate (LT), lithium niobate (LN), aluminum nitride (AlN), lead zirconate titanate piezoelectric ceramic (PZT), or zinc oxide (ZnO). Multiple interdigital transducers 201 are formed on the substrate 200. The interdigital transducers 201 are the main functional components of the SAW filter; they convert the input electrical signal into a surface acoustic wave through the piezoelectric effect and convert the acoustic signal back into an electrical signal at the output, thereby achieving the filtering function. The interdigital transducers 201 are made of materials including, but not limited to, gold, silver, aluminum, copper, tungsten, titanium, nickel, or other metal alloys.

[0044] The supporting wall includes a plurality of first support members 203a. The plurality of first support members 203a are disposed vertically on the substrate 200; that is, disposed along the Z-axis on the substrate 200. Furthermore, the first support members 203a extend along the surface of the substrate 200 according to product requirements and form a plurality of cavities. Each interdigital transducer 201 is respectively housed in each of the cavities. It should be noted that the first support members 203a are not only used to form the cavities but also to cooperate with and support the cover plate 205. However, in the subsequent WLP packaging process, especially in large-capacity cavities, the supporting force provided by the first support members 203a to the cover plate 205 is insufficient to balance the packaging pressure, easily causing the cover plate 205 to collapse, thereby affecting the device performance. Therefore, in the supporting wall provided in this embodiment, a plurality of second support members 204a are also provided. The second support member 204a is located in the cavity with a large capacity, and is used to improve the support effect of the support wall and prevent the cover plate 205 from collapsing.

[0045] Based on this, the plurality of cavities enclosed by the first support member 203a can be divided into a first cavity S1 and a second cavity S2. The first cavity S1 has a smaller capacity, and the supporting force provided by the first support member 203a surrounding the first cavity S1 is sufficient to balance the sealing pressure. Furthermore, the probability of collapse of the corresponding portion of the cover plate 205 is low, so there is no need to install the second support member 204a therein. However, the second cavity S2 has a larger capacity than the first cavity S1, and / or there are other factors requiring stronger support. Therefore, one or more second support members 204a need to be installed in the second cavity S2 to improve the support effect on the cover plate 205. It should be noted that in other examples, the plurality of cavities enclosed by the first support member 203a can all be either the first cavity S1 or both the second cavity S2. However, for ease of explanation, this embodiment uses the simultaneous inclusion of the first cavity S1 and the second cavity S2 as an example for specific description.

[0046] In the first example, please refer to Figure 3 and Figure 4All the first support members 203a surround the first cavity S1 and the second cavity S2, while all the second support members 204a are located within their respective second cavities S2 and are directly formed on the substrate 200. Vertically, i.e., along the Z-axis, the height of the second support member 204a is greater than the height of the first support member 203a. Therefore, since the cover plate 205 needs to seal each of the first cavities S1 and the second cavities S2, and the first support members 203a surrounding the first cavity S1 have the same vertical height, while the vertical height of the first support members 203a surrounding the second cavity S2 is lower than the height of the second support members 204a inside it, the portion of the cover plate 205 covering the first cavity S1 is planar and contacts the top surface of the first support member 203a; while the portion of the cover plate 205 covering the second cavity S2 is arched and contacts the top surfaces of the first support member 203a and the second support member 204a. Thus, as... Figure 4 As shown, the cover plate 205 has a curved structure overall. When the cover plate 205 is subjected to a vertically downward sealing pressure, the curved shape of the cover plate 205 can decompose the sealing pressure into vertical and horizontal components, thereby effectively reducing the vertical force on the cover plate 205 and the supporting wall, which helps to alleviate the collapse problem of the cover plate 205.

[0047] Optionally, to ensure that the portion of the cover plate 205 corresponding to the second cavity S2 is subjected to balanced forces, the second support member 204a is located at least in the central region of the corresponding second cavity S2. For example, the second support member 204a abuts against the arched apex of the portion of the cover plate 205, and / or the second support member 204a abuts against the central region where the arched apex is located.

[0048] Based on the same concept, in the second example, such as Figure 3 and Figure 5As shown, a portion of the first support member 203a is located within the second cavity S2, and the top surface of the second support member 204a located within the second cavity S2 is connected to the top surface of the first support member 203a located within the second cavity S2. Within the second cavity S2, the second support member 204a extends in a direction perpendicular to the top surface of the first support member 203a. In other words, the first support member 203a and the second support member 204a located within the second cavity S2 are stacked. Based on this, compared to the top surface height of the first support member 203a surrounding the second cavity S2, the top surface height of the second support member 204a located within the second cavity S2 is higher. This allows the portion of the cover plate 205 covering the second cavity S2 to be arched, thereby dispersing the sealing pressure, reducing the vertical force on the cover plate 205 and the supporting wall, preventing the cover plate 205 from collapsing, and improving product yield.

[0049] Optionally, within the second cavity S2, the length of the second support member 204a in the Y-axis direction may be equal to or less than the length of the first support member 203a. However, to ensure that the cover plate 205 is subjected to balanced forces, the second support member 204a is located at least in the central region of the second cavity S2; that is, the second support member 204a abuts against the dome and / or the central region of the dome of the cover plate 205 corresponding to the second cavity S2.

[0050] Furthermore, in the third example, such as Figure 6 and Figure 7 As shown, some of the first support members 203a are located within the second cavity S2, and the plurality of second support members 204a are located on the top surface of the corresponding first support members 203a, extending in two directions: perpendicular and parallel to the top surface of the first support members 203a. Based on the above second example, it can be seen that by placing the second support members 204a on the top surface of the first support members 203a, the top surface of the supporting wall can be made to have varying heights. Furthermore, the cover plate 205 needs to cover the top surface of the supporting wall to seal each cavity. Therefore, since the cover plate 205 is in contact with the top surfaces of some of the first support members 203a and each of the second support members 204a, the surface height of the cover plate 205 inevitably changes with the varying heights of the top surfaces of the connected first support members 203a and second support members 204a. This results in the cover plate 205 having a curved surface structure. Figure 7As shown, the portion of the cover plate 205 covering the second cavity S2 is arched. When the cover plate 205 is subjected to a vertically downward sealing pressure, the arched portion of the cover plate 205 can decompose the sealing pressure into a vertical component and a horizontal component, thereby effectively reducing the vertical force on the cover plate 205 and the supporting wall, which helps to alleviate the collapse problem of the cover plate 205.

[0051] Furthermore, the second support member 204a extends in a direction parallel to the top surface of the first support member 203a. That is, the second support member 204a extends along the plane containing the X-axis or the X-axis-Y-axis. In the X-axis direction, the width of the second support member 204a is greater than the width of the first support member 203a. Therefore, in the X-axis-Z-axis plane, the first support member 203a and the second support member 204a combine to form a "T"-shaped structure. Compared to the second support member 204a in the second example, the second support member 204a in the third example has a larger top surface area, thereby increasing the contact area with the cover plate 205, further promoting the decomposition of WLP packaging pressure, improving the support effect of the support wall on the cover plate 205, and effectively alleviating the collapse problem of the cover plate 205.

[0052] To balance the forces on the cover plate 205 and improve support stability, the first support member 203a located within the second cavity S2 extends and penetrates the central region of the second cavity S2, and the second support member 204a is disposed on the top surface of the first support member 203a relative to the central region; that is, each of the second support members 204a is disposed relative to the central region of the second cavity S2, thus supporting the portion of the cover plate 205 covering the central region of the second cavity S2. Specifically, the second support member 204a may abut against the arched apex of the arched portion of the cover plate 205, and / or the second support member 204a abuts against the central region where the arched apex is located. Furthermore, within the second cavity S2, depending on the capacity of the second cavity S2, one or more of the first support members 203a may be provided. For example... Figure 8 As shown, the second cavity S2 with a larger capacity is provided with two first support members 203a; while the second cavity S2 with a relatively smaller capacity is provided with one first support member 203a. Furthermore, one or more second support members 204a can be provided on the same first support member 203a. Optionally, when multiple second support members 204a are provided on the same first support member 203a, the second support members 204a are evenly spaced along the extending direction of the first support member 203a to ensure balanced force distribution. For example, as...Figure 6 and Figure 7 As shown, a first support member 203a is provided in the second cavity S2, and three spaced second support members 204a are connected to the top surface of the first support member 203a to support the corresponding parts of the cover plate 205.

[0053] Furthermore, due to the limited ability to fabricate the thickness of the first support 203a and the second support 204a along the Z-axis during the manufacturing process, in the fourth example, as... Figure 6 and Figure 9 As shown, to increase the height of the first support member 203a and the second support member 204a within the second cavity S2, based on the structures described in the first, second, and third examples, the support pad 208 can be pre-fabricated on a portion of the substrate 200 within the second cavity S2. Then, the first support member 203a or the second support member 204a can be fabricated on the top surface of the support pad 208. This increases the top surface height of the second support member 204a within the second cavity S2, ensuring that the top surface heights of the support walls are not uniform. This allows for the fabrication of a curved cover plate 205, facilitating pressure distribution during encapsulation, reducing vertical forces, and alleviating the collapse problem of the cover plate 205. Optionally, the support pad 208 can be fabricated simultaneously with the interdigital transducer 201 and the metal pad 202; in this case, the material of the support pad 208 can be the same as that of the interdigital transducer 201 and the metal pad 202.

[0054] For further details, please refer to Figures 3 to 9 The SAW filter further includes multiple metal pads 202, multiple metal pillars 206, and multiple metal balls 207. The metal pads 202, metal pillars 206, and metal balls 207 are one-to-one and sequentially connected to form a metal lead-out structure for transmitting electrical signals. Specifically, the metal pads 202 are located on the substrate 200 and are in contact with the bottom surface of the portion of the first support member 203a surrounding the cavity. The two opposing surfaces of the metal pillars 206 are respectively in contact with the corresponding metal pads 202 and metal balls 207, and the metal pillars 206 sequentially penetrate the corresponding first support member 203a and the cover plate 205 located on the first support member 203a. Optionally, the materials of the metal pads 202 and the metal pillars 206 include, but are not limited to, gold, silver, aluminum, copper, tungsten, titanium, nickel, or other metal alloys. The materials of the metal balls 207 include, but are not limited to, tin, tin-silver alloys, and other welding metals.

[0055] It should be noted that the structures corresponding to the four examples above can each form a separate SAW filter, or they can be fully or partially integrated into the same SAW filter. For example, the same SAW filter may include the semiconductor structures corresponding to the first and second examples; or, it may include the semiconductor structures corresponding to the third and fourth examples.

[0056] To further illustrate the SAW filter provided in this embodiment, this embodiment also provides a first method for preparing a SAW filter, to form SAW filters corresponding to the first example and a fourth example based on the first example. For details, please refer to... Figure 4 and Figures 10-17 The method for fabricating the SAW filter includes:

[0057] Step 1 S11: Please refer to Figure 10 and Figure 11 A substrate 200 is provided, and a plurality of interdigital transducers 201 are formed on the substrate 200.

[0058] Optionally, the interdigital transducer 201 can be formed on the surface of the substrate 200 using processes such as sputtering or electroplating. The metal pad 202 can also be formed simultaneously with the interdigital transducer 201. Furthermore, for the SAW filter described in the fourth example, the support pad 208 can also be formed simultaneously with the interdigital transducer 201 and the metal pad 202.

[0059] Step 2 S12: Please refer to Figure 4 and Figure 12 A first support material layer 203 and a second support material layer 204 are formed on the substrate 200, and the vertical height of the second support material layer 204 is greater than the vertical height of the first support material layer 203.

[0060] Specifically, the first support material layer 203 covers a portion of the substrate 200, as well as the metal pad 202 and a portion of the interdigital transducer 201 formed on the substrate 200; the second support material layer 204 covers a portion of the substrate 200 and a portion of the interdigital transducer 201 formed on the substrate 200. In other words, the second support material layer 204 is used to form the second support member 204a, and the area covered by the second support material layer 204 corresponds to the area where the second cavity S2 is located. The first support material layer 203 is used to form the first support member 203a, and the first support material layer 204 covers the area on the substrate 200 not covered by the two support material layers 203. That is, the area where the first cavity S1 is located and other support areas.

[0061] Furthermore, the vertical height of the second support material layer 204 is greater than the vertical height of the first support material layer 203, so that the vertical height of the subsequently formed second support member 204a is greater than the vertical height of the first support member 203a. This allows the portion of the cover plate 205 corresponding to the second chamber S2 to have an arched shape, thereby achieving pressure distribution of the sealing pressure, reducing vertical force, and alleviating the collapse problem of the cover plate 205.

[0062] Optionally, both the first support material layer 203 and the second support material layer 204 are photosensitive materials, which can be dry films or wet films, and can be positive or negative. For example, both the first support material layer 203 and the second support material layer 204 are negative dry films.

[0063] Step 3 S13: Please refer to Figure 13 A first photolithography process is performed on the first support material layer 203 and the second support material layer 204 using a first photomask M1 to expose at least a portion of the surface of the substrate 200 located at the bottom of the first support material layer 203.

[0064] Since the vertical height of the second support material layer 204 is greater than that of the first support material layer 203, under the same photomask and process parameters, the first support material layer 203 and the second support material layer 204 will be photolithographically removed by the same thickness. Therefore, when the surface of the substrate 200 and the metal pad 202 located at the bottom of the first support material layer 203 is exposed after exposure and development, the second support material layer 204 still retains part of its structure covering the surface of the substrate 200 and the interdigital transducer 201. Furthermore, when the support pad 208 is provided, the remaining part of the second support material layer 204 after photolithography also covers the support pad 208.

[0065] Based on this, after the first photolithography process is completed, the first support material layer 203 is photolithographically formed to form the first support member 203a. The first support member 203a surrounds each of the interdigital transducers 201 to form a plurality of first cavities S1 and second cavities S2. At the same time, the first support member 203a also surrounds and exposes a portion of the metal pad 202.

[0066] Step 4 S14: Please refer to Figure 14 A second photolithography process is performed on the second support material layer 204 using a second photomask M2 to expose at least a portion of the surface of the substrate 200 located at the bottom of the second support material layer 204.

[0067] like Figure 14As shown, since the first photolithography process has not completely etched the second support material layer 204, the second support member 204a has not yet been formed. Therefore, a second photomask M2 is needed to continue performing a second photolithography process on the second support material layer 204 to expose the surface of the substrate 200 and the interdigital transducer 201 covered by the second support material layer 204, and to retain the portion of the second support material layer 204 located in the second chamber S2 as the second support member 204a. Specifically, when the second chamber S2 does not contain the support pad 208, the bottom surface of the photolithographically formed second support member 204a is directly in contact with the substrate 200; while when the support pad 208 is present, the bottom surface of the second support member 204a is in contact with the top surface of the corresponding support pad 208.

[0068] Step 5 S15: Please refer to Figure 15 A cover plate 205 is formed, and the cover plate 205 is in contact with the top surface of a portion of the first support member 203a and all of the second support members 204a to seal each of the cavities.

[0069] Optionally, the cover plate 205 is a dry film. The cover plate 205 is in contact with the top surface of the first support member 203a surrounding the cavity, and with all the second support members 204a located within the cavity. Since the top surface height of the second support members 204a is greater than the top surface height of the remaining first support members 203a, the top surface height of the support wall is uneven, resulting in a certain height difference. Therefore, the portion of the cover plate 205 covering the cavity is arched, and the overall shape of the cover plate 205 is a curved structure. When subjected to encapsulation pressure, the curved structure can decompose the force into horizontal and vertical components, thereby reducing the vertical force on the cover plate 205, effectively preventing the cover plate 205 from collapsing, thus protecting the cavity and the interdigital transducer 201, and improving device performance.

[0070] Step 6 S16: Please refer to Figure 16 and Figure 17 This forms a metal pillar 206 and a metal ball 207; wherein, the metal pillar 206 is in contact with the corresponding metal pad 202 and metal ball 207 on its two opposite surfaces, and the metal pillar 206 penetrates the first support member 203a and the cover plate 205 located on the first support member 203a.

[0071] Specifically, since the cover plate 205 obscures the accommodating position of the metal pillar 206, a third photomask M3 is needed to expose the cover plate 205 to form a through hole T in the portion of the cover plate 205 corresponding to the metal pad 202, thereby exposing a portion of the surface of the metal pad 202. Subsequently, processes such as sputtering and electroplating are used to form the metal pillar 206 within the through hole T, and the metal sphere 207 is formed on the top surface of the metal pillar 206.

[0072] Based on the same concept, this embodiment also provides a second method for fabricating a SAW filter to form the SAW filters described in the second example, the third example, and the corresponding fourth example. For details, please refer to... Figures 5-11 and Figures 18-27 The method for fabricating the SAW filter includes:

[0073] Step 1 S21: Please refer to Figure 10 and Figure 11 A substrate 200 is provided, and a plurality of interdigital transducers 201 are formed on the substrate 200. The preparation process of step S21 can refer to the specific preparation process of step S11, and will not be described in detail here.

[0074] Step 2 S22: Please refer to Figure 18 and Figure 19 A first support material layer 203 is formed on the substrate 200.

[0075] like Figure 18 As shown, the first support material layer 203 covers the substrate 200 and the surfaces of the interdigital transducer 201 and the metal pad 202 on the substrate 200, for forming the first support member 203a. And, as... Figure 19 As shown, when the support pad 208 is formed on the substrate 200, the first support material layer 203 also covers the support pad 208.

[0076] Step 3 S23: Please refer to Figures 18 to 20 A third photolithography process is performed on the first support material layer 203 using a first photomask M1 to expose the surface of a portion of the substrate 200, the interdigital transducer 201, and a portion of the metal pad 202 located at the bottom of the first support material layer 203.

[0077] It is understood that the third photolithography process in step S23 is similar to the first photolithography process in step S13, both forming the first support member 203a. However, the difference is that the third photolithography process simultaneously forms the first support member 203a located within the second cavity S2. Furthermore, the first support member 203a located within the second cavity S2 can be formed directly on the substrate 200 or on the support pad 208.

[0078] Step 4 S24: Please refer to Figure 21 A second support material layer 204 is attached to the surface of the first support member 203a.

[0079] Step 5 S25: Please refer to Figure 21 and Figure 22 The fourth photolithography process is performed on the second support material layer 204 using the fifth photomask M5, so as to retain a portion of the second support material layer 204 on the top surface of the first support member 203a located in the second cavity, as the second support member 204a.

[0080] The material of the second support material layer 204 can be the same as or different from that of the first support material layer 203. For example, if the second support material layer 204 is also a negative dry film, then the second support material layer 204 is exposed using a second photomask M2. After development, a portion of the second support material layer 204 on the first support member 203a is removed, leaving only a portion of the second support material layer 204 on the top surface of the first support member 203a within the second cavity S2, serving as the second support member 204a.

[0081] For further details, please refer to Figure 21 and Figure 22 The fifth photomask M5 can be the same as the second photomask M2 in step four S14. Using this fifth photomask M5 as a mask, the width of the second support member 204a formed by photolithography on the X-axis is equal to the width of the first support member 203a. That is, by superimposing the second support member 204a on the first support member 203a, the height of the top surface of the support wall located within the second cavity S2 is only increased. Based on this, a SAW filter as described in the second example or the fourth example based on the second example can be further fabricated.

[0082] Or, such as Figure 23 and Figure 24As shown, the width of the exposed opening in the fifth photomask M5 is slightly larger than the width of the exposed opening in the second photomask M2 in step four S14. Therefore, under the action of the fifth photomask M5, the width of the second support member 204a formed by photolithography on the X-axis is greater than the width of the first support member 203a. That is, the second support member 204a not only increases the height of the top surface of the support wall located in the second cavity S2, but also increases the width of the top surface of the support wall located in the second cavity S2. Based on this, a SAW filter as described in the third example or the fourth example based on the third example can be further fabricated.

[0083] Step 6 S26: Please refer to Figure 25 A cover plate 205 is formed, and the cover plate 205 is in contact with the top surface of a portion of the first support member 203a and all of the second support members 204a to seal each of the cavities.

[0084] Step 7 S27: Please refer to Figure 26 and Figure 27 This forms a metal pillar 206 and a metal ball 207; wherein, the metal pillar 206 is in contact with the corresponding metal pad 202 and metal ball 207 on its two opposite surfaces, and the metal pillar 206 penetrates the first support member 203a and the cover plate 205 located on the first support member 203a.

[0085] The specific implementation processes of steps six (S26) and seven (S27) can be referred to the preparation processes in steps five (S15) and six (S16), and will not be repeated here in this embodiment. Figures 25 to 27 The fabrication process of the SAW filter corresponding to the third example is the same for the second and fourth examples, involving the fabrication of the cover plate 205, metal pillar 206, and metal ball 207, except that the structures located within the second cavity S2 are different. Therefore, no corresponding illustrations are provided in this embodiment; please refer to [the relevant documentation]. Figures 25 to 27 or Figures 15 to 17 And its corresponding records.

[0086] Based on the same concept, this embodiment also provides an electronic device. The electronic device includes the SAW filter described above. Exemplarily, the electronic device is a radio frequency (RF) device. Optionally, the SAW filter in the electronic device can be fabricated using the first and / or second SAW filter fabrication methods described above.

[0087] In summary, this embodiment provides a SAW filter and electronic device. The supporting wall of the SAW filter includes multiple first support members 203a and several second support members 204a, with at least some of the first support members 203a surrounding each interdigital transducer 201 to form multiple cavities; the second support members 204a are located within some of the cavities. The second support members 204a are located on the substrate 200 or on the first support members 203a, and the top surface height of the second support member 204a is higher than the top surface height of the first support member 203a, resulting in a varying top surface height of the supporting wall. Consequently, the cover plate 205 covering the top surface of the supporting wall will form a curved surface. The curved surface of the cover plate 205 can decompose the pressure generated during WLP packaging into vertical and horizontal components, thereby reducing the vertical force on the cover plate 205 and the supporting wall, which helps alleviate the collapse problem of the cover plate 205. Furthermore, the second support member 204a can also extend in a direction parallel to the top surface of the first support member 203a to increase the contact area between the support wall and the cover plate 205, further promoting the decomposition of WLP packaging pressure, improving the support effect of the support wall on the cover plate 205, effectively alleviating the collapse problem of the cover plate 205, protecting the cavity and the interdigital transducer 201, and helping to improve device performance.

[0088] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the present invention's technical solutions using the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention's technical solutions. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention's technical solutions, shall still fall within the protection scope of the present invention's technical solutions.

Claims

1. A SAW filter, characterized in that, include: A substrate on which multiple interdigital transducers are formed; A supporting wall, the supporting wall comprising a plurality of first supports and a plurality of second supports; the first supports are located on the substrate, and at least a portion of the first supports surround the plurality of interdigital transducers to form a plurality of cavities; the plurality of second supports are located within portions of the cavities; and, A plurality of second supports are located on the substrate and are at a height greater than that of the first support in the vertical direction; and / or, a portion of the first support is located within a portion of the cavity and a plurality of second supports are located on the top surface of the first support within the cavity and extend at least in the vertical direction. A cover plate covers the top surface of the supporting wall and is connected to the portion of the first support member and the plurality of second support members surrounding the cavity to seal the plurality of cavities.

2. The SAW filter according to claim 1, characterized in that, The plurality of cavities include a first cavity and a second cavity; wherein the first cavity contains the interdigital transducer; the second cavity contains at least the interdigital transducer and the second support member, and the second support member is located at least in the central region of the corresponding second cavity.

3. The SAW filter according to claim 2, characterized in that, The second cavity also houses the first support member, and the top surface of the first support member is connected to several second support members.

4. The SAW filter according to claim 3, characterized in that, Within the second cavity, the second support extends in a direction perpendicular to the top surface of the first support.

5. The SAW filter according to claim 3, characterized in that, Within the second cavity, the second support extends in a direction perpendicular to and parallel to the top surface of the first support, such that in the direction parallel to the top surface of the first support, the width of the second support is greater than the width of the first support.

6. The SAW filter according to claim 2, characterized in that, The second cavity also contains a support pad, which is located on the substrate and is connected to the first support member or the second support member.

7. The SAW filter according to any one of claims 2 to 6, characterized in that, The cover plate has a curved structure; wherein, the portion of the cover plate covering the top surface of the first cavity is planar; and the portion of the cover plate covering the top surface of the second cavity is arched.

8. The SAW filter according to claim 7, characterized in that, The second support abuts against the arched portion of the cover plate and / or the central area where the arch is located.

9. The SAW filter according to claim 1, characterized in that, The SAW filter further includes: multiple metal pads, multiple metal pillars, and multiple metal balls; the metal pads, metal pillars, and metal balls are one-to-one correspondences and connected sequentially; wherein... The metal pad is located on the substrate and is in contact with the bottom surface of the portion of the first support member surrounding the cavity; the two opposing surfaces of the metal pillar are respectively in contact with the corresponding metal pad and the metal ball, and the metal pillar penetrates the corresponding first support member and the cover plate located on the first support member.

10. An electronic device, characterized in that, Includes the SAW filter as described in any one of claims 1 to 9.

Images