Filter

Abstract

The utility model provides a filter, comprising a piezoelectric substrate on which an interdigital transducer electrode is arranged; a support layer including a peripheral support structure disposed on the piezoelectric substrate around a periphery of a region in which the interdigital transducer electrode is disposed, and a plurality of internal support structures; the internal supporting structure is arranged on the piezoelectric substrate below the metal bump, and the internal supporting structure is surrounded by the peripheral supporting structure; the covering layer is located on the supporting layer, and a cavity is defined by the covering layer, the supporting layer and the piezoelectric substrate; the rewiring layer is positioned on the covering layer; and a plurality of metal bumps on the rewiring layer. According to the utility model, the internal supporting structure is arranged below the metal bumps, so that the anti-pressure capability of the filter can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to a filter. Background Art

[0002] The SAW (Surface Acoustic Wave) filter has a high process complexity due to its unique cavity structure, and is very likely to collapse during the subsequent plastic packaging process, resulting in the scrapping of the entire module. The wall (cavity sidewall) structure used in the past is generally distributed around the chip, with the middle suspended; in recent years, there have also been cavity sidewalls added to the non-functional area in the middle of the chip to improve the filter's pressure resistance. However, with the miniaturization of filters, the requirements for the filter's pressure resistance are getting higher and higher, so it is necessary to provide a new type of filter that can improve the overall pressure resistance. Utility Model Content

[0003] The utility model aims to provide a filter to improve the overall pressure resistance of the filter.

[0004] In order to achieve the above-mentioned object and other related objects, the utility model provides a filter, comprising:

[0005] a piezoelectric substrate on which interdigital transducer electrodes are disposed;

[0006] a support layer including an outer peripheral support structure and a plurality of inner support structures, wherein the outer peripheral support structure is disposed on the piezoelectric substrate around the periphery of a region in which the interdigital transducer electrodes are disposed, and the inner support structure is disposed on the piezoelectric substrate below the metal bump and is surrounded by the outer peripheral support structure;

[0007] A covering layer, located on the supporting layer and surrounding the supporting layer and the piezoelectric substrate to form a cavity;

[0008] a redistribution layer, located on the cover layer;

[0009] A plurality of metal bumps are located on the rewiring layer.

[0010] Optionally, in the filter, when looking down at the piezoelectric substrate, the peripheral support structure is a rectangular frame.

[0011] Optionally, in the filter, when looking down at the piezoelectric substrate, the multiple internal support structures are parallel to the short sides of the rectangular frame.

[0012] Optionally, in the filter, the multiple internal support structures include a first internal support structure and a second internal support structure. When looking down at the piezoelectric substrate, when the ends of the first internal support structure and the second internal support structure in a first direction parallel to the short side of the rectangular frame are set as the first end, and the ends on the opposite side of the first direction are set as the second end, the first end of the first internal support structure contacts the peripheral support structure and the second end does not contact the peripheral support structure, the second end of the second internal support structure contacts the peripheral support structure and the first end does not contact the peripheral support structure, and the gap between the second end of the first internal support structure and the peripheral support structure is larger than the gap between the first end of the second internal support structure and the peripheral frame supporting layer.

[0013] Optionally, in the filter, the line width of the rectangular frame is greater than or equal to 30 nm.

[0014] Optionally, in the filter, the length of the internal support structure is shorter than the length of the short side of the rectangular frame.

[0015] Optionally, in the filter, different internal support structures are arranged on the same horizontal line or on different horizontal lines.

[0016] Optionally, in the filter, the height of the support layer is greater than the height of the interdigital transducer electrode.

[0017] Optionally, in the filter, the height of the internal support structure is the same as the height of the peripheral support structure.

[0018] Optionally, in the filter, the metal bumps are solder balls.

[0019] Compared with the prior art, the technical solution of the utility model has the following beneficial effects:

[0020] The utility model adds an internal support structure of the support layer below the metal bump, and the internal support structure is used to receive the stress generated by the metal bump during the welding process, reduce the deformation of the cover layer, and improve the pressure resistance of the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a filter according to an embodiment of the utility model;

[0022] Figure 2 is a top view of a filter according to an embodiment of the present utility model;

[0023] Figure 3It is a structural schematic diagram of a product after executing step S2 in the filter preparation method according to an embodiment of the utility model;

[0024] Figure 4 It is a structural schematic diagram of a product after executing step S3 in the filter preparation method according to an embodiment of the utility model;

[0025] Figure 5 It is a structural schematic diagram of a product after executing step S4 in the filter preparation method of an embodiment of the utility model;

[0026] Figure 6 It is a structural schematic diagram of a product after executing step S5 in the filter preparation method according to an embodiment of the utility model;

[0027] Figure 1 to Figure 6 middle,

[0028] 10 - piezoelectric substrate, 20 - interdigital transducer electrode, 30 - support layer, 301 - peripheral support structure, 302 - internal support structure, 40 - cover layer, 50 - redistribution layer, 60 - metal bump, 70 - cavity. DETAILED DESCRIPTION

[0029] The filter proposed by the utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the utility model will become clearer. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model.

[0030] The utility model provides a long strip internal support structure below the metal internal support structure to receive the stress generated by the metal bump during welding (such as the pressure exerted by the metal filler during reflow soldering), reduce the deformation of the cover layer, and improve the pressure resistance of the filter. The filter of this embodiment is preferably a SAW filter.

[0031] See also Figure 1 and Figure 2 , the filter provided by the utility model may include:

[0032] A piezoelectric substrate 10, on which an interdigital transducer electrode 20 is disposed;

[0033] A support layer 30, comprising a peripheral support structure 301 and a plurality of internal support structures 302, wherein the peripheral support structure 301 is arranged on the piezoelectric substrate 10 around the periphery of the region where the interdigital transducer electrodes 20 are arranged; the internal support structure 302 is arranged on the piezoelectric substrate 10 below the metal bump 60, and the internal support structure 302 is surrounded by the peripheral support structure 301;

[0034] The covering layer 40 is located on the supporting layer 30 and is surrounded by the supporting layer 30 and the piezoelectric substrate 10 to form a cavity 70;

[0035] A redistribution layer 50 , located on the cover layer 40 ;

[0036] A plurality of metal bumps 60 are located on the redistribution layer 50 .

[0037] In the present embodiment, the piezoelectric substrate 10 may be formed of a piezoelectric material, such as lithium tantalate or lithium niobate. When looking down at the piezoelectric substrate 10, the overall shape of the filter is preferably a rectangle defined by the X-axis direction and the Y-axis direction. The interdigital transducer electrode 20 may be an electrode disposed on the upper surface (main surface) of the piezoelectric substrate 10. The interdigital transducer electrode 20 is preferably composed of a metal or alloy such as Ti, Al, Cu, Au, Pt, Ag, Pd, Ni, or is composed of at least one of the above metals or alloys. In the present embodiment, the outer periphery of the piezoelectric substrate 10 (the periphery of the area where the interdigital transducer electrode 20 is disposed) may also be formed with a terminal electrode (not shown in the figure), which is electrically connected to the interdigital transducer electrode 20. The material of the terminal electrode is preferably the same as the material of the interdigital transducer electrode 20.

[0038] The support layer 30 may include an outer peripheral support structure 301 and a plurality of inner support structures 302. In this embodiment, the support layer 30 may be made of at least one material selected from the group consisting of polyimide, epoxy resin, benzocyclobutene, polybenzoxazole, metal, silicon oxide and silicon nitride.

[0039] The peripheral support structure 301 is arranged on the piezoelectric substrate 10 around the periphery of the area where the interdigital transducer electrodes 20 are arranged. In this embodiment, the cross section of the peripheral support structure 301 parallel to the piezoelectric substrate 10 is preferably a rectangular frame (that is, when looking down at the piezoelectric substrate 10, the overall shape of the peripheral support structure 301 is a rectangular frame), and the line width of the rectangular frame is greater than or equal to 30 μm, so as to provide better support force. For example Figure 2 The peripheral support structure 301 in the embodiment can be a rectangular frame consisting of a short side along the X-axis direction and a long side along the Y-axis direction. The peripheral support structure 301 supports the cover layer 40, and the peripheral support structure 301, the cover layer 40 and the piezoelectric substrate 10 are arranged to form a cavity 70, the peripheral support structure 301 serves as a side wall of the cavity, and the interdigital transducer electrode 20 is located in the cavity 70. In this embodiment, the height of the peripheral support structure 301 is greater than the height of the interdigital transducer electrode 20.

[0040] The number of the internal support structures 302 is preferably multiple, and the internal support structures 302 are preferably in the shape of long strips. In the present embodiment, the internal support structure 302 is preferably arranged directly below the metal bump 60, so as to better receive the stress generated by the metal bump 60 during the welding process, reduce the deformation of the covering layer 40, and improve the compressive strength of the filter. The length of each of the internal support structures 302 may be the same or different, and the length of the internal support structure 302 is less than the length of the short side of the peripheral support structure 301 (rectangular frame). In the present embodiment, the longer the length of the internal support structure 302, the better it can support the covering layer 40, and the greater the compressive strength of the obtained filter. The internal support structure 302 is preferably parallel to the short side of the cavity 70 and also parallel to the short side of the peripheral support structure 301 (rectangular frame), but is not limited thereto. Different internal support structures 302 may be arranged on the same horizontal line or on different horizontal lines. For example, Figure 2 The internal support structure L1 and the internal support structure L2 are located on the same horizontal line, and the internal support structure L1 and the internal support structure L3 are located on different horizontal lines, that is, the internal support structure L1 extends along the X-axis direction and can contact the internal support structure L2. The spacing between the internal support structure L1 and the internal support structure L3 can be set according to the distance between adjacent metal bumps 60. In this embodiment, one end of the internal support structure 302 can contact the peripheral support structure 301 to obtain higher compressive resistance. The multiple internal support structures 302 may include a first internal support structure and a second internal support structure. In a state of looking down at the piezoelectric substrate 10, when the ends of the first internal support structure and the second internal support structure in the first direction (positive direction of the X-axis) are set as the first end, and the ends on the opposite side of the first direction are set as the second end, the first end of the first internal support structure contacts the peripheral support structure and the second end does not contact the peripheral support structure, and the second end of the second internal support structure contacts the peripheral support structure and the first end does not contact the peripheral support structure. For example, the internal support structure L2 is the first internal support structure, and the internal support structure L3 is the second internal support structure. In this embodiment, the gap between the second end of the first internal support structure and the peripheral support structure is preferably greater than the gap between the first end of the second internal support structure and the peripheral frame support layer, that is, the length of the first internal support structure is preferably less than the length of the second internal support structure. Since the bonding force between the internal support structure 302 with a large length and the covering layer 40 and the piezoelectric substrate 10 is relatively large, in the subsequent film tearing (such as film reduction, etc.) process, tearing the film from the side of the internal support structure 302 with a large length can better protect the product and improve reliability.

[0041] In this embodiment, the material of the internal support structure 302 is preferably the same as that of the peripheral support structure 301 , and the height of the internal support structure 302 is preferably the same as that of the peripheral support structure 301 .

[0042] In this embodiment, the cover layer 40 is located on the support layer 30 and covers the cavity 70, that is, the cover layer 40, the support layer 30 and the piezoelectric substrate 10 are arranged to form the cavity 70. The cover layer 40 serves as the top of the cavity, and the interdigital transducer electrode 20 is arranged in the cavity 70. The cover layer 40 can be made of at least one material selected from polyimide, epoxy resin, benzocyclobutene, polybenzoxazole, metal, silicon oxide and silicon nitride.

[0043] The rewiring layer 50 is located on the cover layer 40 and extends to cover a portion of the piezoelectric substrate 10. In this embodiment, the rewiring layers 50 are interconnected, and the rewiring layers 50 are also electrically connected to the terminal electrodes. The material of the rewiring layer 50 can be composed of metals or alloys such as Ti, Cu, Au, Ni, or a material containing at least one of the above metals or alloys.

[0044] In this embodiment, the metal bump 60 is located on the rewiring layer 50, and the number of the metal bump 60 is preferably multiple. The metal bump 60 is preferably a solder ball, such as a tin ball, but is not limited thereto.

[0045] See also Figures 3 to 6 The method for preparing the filter may include the following steps:

[0046] Step S1: providing a piezoelectric substrate 10, on which an interdigital transducer electrode 20 is disposed;

[0047] Step S2: forming a support layer 30 on the piezoelectric substrate 10, wherein the support layer 30 includes a peripheral support structure 301 and a plurality of internal support structures 302, wherein the peripheral support structure 301 is arranged on the piezoelectric substrate 10 around the periphery of the region where the interdigital transducer electrodes 20 are arranged, and the internal support structure 302 is arranged on the piezoelectric substrate 10 below the metal bump 60, and the internal support structure 302 is surrounded by the peripheral support structure 301;

[0048] Step S3: forming a covering layer 40 on the supporting layer 30 , wherein the covering layer 40 , the supporting layer 30 and the piezoelectric substrate 10 surround a cavity 70 ;

[0049] Step S4: forming a redistribution layer 50 on the cover layer 40;

[0050] Step S5 : forming a plurality of metal bumps 60 on the redistribution layer 50 .

[0051] See also Figure 3 , perform step S1 to provide a piezoelectric substrate 10. In the present embodiment, the piezoelectric substrate 10 may be formed of a piezoelectric material, such as lithium tantalate or lithium niobate. Then, an interdigital transducer electrode 20 is formed on the piezoelectric substrate 10. The interdigital transducer electrode 20 is preferably composed of a metal or alloy such as Ti, Al, Cu, Au, Pt, Ag, Pd, Ni, or is composed of at least one of the above metals or alloys. In the present embodiment, while forming the interdigital transducer electrode 20, a terminal electrode may also be formed on the periphery of the piezoelectric substrate 10, and the terminal electrode is electrically connected to the interdigital transducer electrode 20. The material of the terminal electrode is preferably the same as that of the interdigital transducer electrode 20.

[0052] Continue reading Figure 3 , perform step S2 to form a support layer 30 on the piezoelectric substrate 10. The support layer 30 can be made of at least one material selected from the group consisting of polyimide, epoxy resin, benzocyclobutene, polybenzoxazole, metal, silicon oxide, and silicon nitride. In this embodiment, the support layer 30 can be formed by processes such as tape pasting and photolithography. The specific process is as follows: provide a support layer dry film, and paste the support layer dry film on the piezoelectric substrate 10 by tape; perform a photolithography process on the support layer dry film to form the support layer 30, and the photolithography process of this step can sequentially include soft baking, exposure, PEB (post-baking), development, and hard baking.

[0053] In the present embodiment, the support layer 30 includes a peripheral support structure 301 and a plurality of internal support structures 302. The peripheral support structure 301 supports the covering layer 40, and the peripheral support structure 301 is arranged on the piezoelectric substrate 10 around the periphery of the area in which the interdigital transducer electrode 20 is arranged. In the present embodiment, the peripheral support structure 301 also covers the terminal electrode. The cross-section of the peripheral support structure 301 parallel to the piezoelectric substrate 10 is preferably a rectangular frame, and the line width of the rectangular frame is greater than or equal to 30nm, and the greater the width, the greater the supporting force of the peripheral support structure 301. In the present embodiment, the height of the peripheral support structure 301 is greater than the height of the interdigital transducer electrode 20,

[0054] In this embodiment, the number of the internal support structure 302 is preferably multiple, and the internal support structure 302 is preferably in the shape of a long strip, and is preferably arranged directly below the metal bump 60, so that the stress generated by the metal bump 60 during the welding process can be better received, the deformation of the cover layer 40 can be reduced, and the compressive resistance of the filter can be improved. In other embodiments, while the internal support structure 302 is arranged directly below the metal bump 60, the internal support structure 302 can also be arranged at other positions to further increase the supporting force of the cover layer. In the state of looking down at the piezoelectric substrate 10, the internal support structure 302 is parallel to the short side of the peripheral support structure 301 (rectangular frame), but is not limited to this. In this embodiment, the height of the internal support structure 302 is greater than the height of the interdigital transducer electrode 20, and is preferably the same as the height of the peripheral support structure 301. The length of the internal support structure 302 is preferably longer than the interdigital transducer electrode 20, and is less than the short side length of the peripheral support structure 301 (rectangular frame), that is, less than the short side length of the cavity 70. In this embodiment, the longer the length of the internal support structure 302 is, the greater the pressure resistance of the obtained filter is.

[0055] The different internal support structures 302 can be arranged on the same horizontal line or on different horizontal lines, and can be arranged specifically according to the actual design layout. In this embodiment, the internal support structures 302 arranged on the same horizontal line have a greater pressure resistance. The arrangement of the internal support structures 302 not on the same horizontal line can be arranged according to the spacing between adjacent metal bumps 60, and preferably, an internal support structure 302 is arranged under each metal bump 60 to increase the pressure resistance of the filter.

[0056] One end of the internal support structure 302 may contact the peripheral support structure 301 to further improve the compressive resistance of the internal support structure. And the multiple internal support structures 302 may include a first internal support structure and a second internal support structure, the first end of the first internal support structure contacts the peripheral support structure and the second end does not contact the peripheral support structure, and the second end of the second internal support structure contacts the peripheral support structure and the first end does not contact the peripheral support structure. In this embodiment, the gap between the second end of the first internal support structure and the peripheral support structure is preferably greater than the gap between the first end of the second internal support structure and the peripheral frame support layer to better protect the product and improve reliability.

[0057] See also Figure 4, perform step S3, form a covering layer 40 on the supporting layer 30 (peripheral supporting structure 301 and internal supporting structure 302), and the covering layer 40, the supporting layer 30 and the piezoelectric substrate 10 are surrounded to form a cavity 70, that is, the filter has a cavity 70 inside, and the cavity 70 is surrounded by the piezoelectric substrate 10, the supporting layer 30 and the covering layer 40. The covering layer 40 can be made of at least one material selected from polyimide, epoxy resin, benzocyclobutene, polybenzoxazole, metal, silicon oxide and silicon nitride. In this embodiment, the covering layer 40 can be formed by processes such as tape filming and photolithography. The specific process is as follows: provide a covering layer dry film, and stick the covering layer dry film on the top of the supporting layer 30 by tape; perform a photolithography process on the covering layer dry film to form the covering layer 40, and the photolithography process of this step can sequentially include exposure, PEB, development and hard baking.

[0058] See also Figure 5 , step S4 is performed to form a rewiring layer 50 on the cover layer 40. The material of the rewiring layer 50 is preferably the same as the material of the interdigital transducer electrode 20, and the rewiring layers 50 are interconnected and electrically connected to the terminal electrodes, and can be specifically designed according to actual circuit requirements. The rewiring method (forming the rewiring layer 50) adopted in this embodiment can increase the possibility of arranging the internal support structure 302 under the metal bump 60.

[0059] In this embodiment, the rewiring layer 50 can be manufactured by sputtering, photolithography, electroplating, degumming and etching processes in sequence. The specific process is: first, a seed layer is sputtered on the top and side walls of the cover layer 40, the side walls of the support layer 30 and the piezoelectric substrate 10; secondly, a pattern required for electroplating is made by coating, exposing and developing a photoresist; then, electroplating is performed to form a metal layer; then, the photoresist is removed; and finally, the rewiring layer 50 is formed by etching.

[0060] See also Figure 6 , perform step S5 to form a plurality of metal bumps 60 on the rewiring layer 50. The number of the metal bumps 60 is preferably multiple, and the shape of the metal bumps 60 is preferably spherical. Further, the metal bumps 60 are preferably solder balls, such as tin balls, but not limited thereto. In this embodiment, the metal bumps 60 required for packaging can be manufactured on the rewiring layer 50 through processes such as electroplating, chemical plating, or ball planting, and the metal bumps 60 are connected to the rewiring layer 50 and the external PCB board through a reflow soldering process.

[0061] The filter provided by the utility model includes: a piezoelectric substrate, on which an interdigital transducer electrode is arranged; a support layer, which includes a peripheral support structure and a plurality of internal support structures, wherein the peripheral support structure is arranged on the piezoelectric substrate around the periphery of the area in which the interdigital transducer electrode is arranged; the internal support structure is arranged on the piezoelectric substrate below the metal bump, and the internal support structure is surrounded by the peripheral support structure; a covering layer, which is located on the supporting layer and is surrounded by the supporting layer and the piezoelectric substrate to form a cavity; a rewiring layer, which is located on the covering layer; and a plurality of metal bumps, which are located on the rewiring layer. The utility model adopts a rewiring method (forming a rewiring layer) to increase the possibility of arranging the internal support structure below the metal bump, and the internal support structure of the support layer arranged below the metal bump can receive the stress generated by the metal bump during the welding process, reduce the deformation of the covering layer, and improve the pressure resistance of the filter.

[0062] In addition, it is understood that although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

[0063] It should also be understood that the utility model is not limited to the specific methods, compounds, materials, manufacturing techniques, usages and applications described herein, which can vary. It should also be understood that the terms described herein are only used to describe specific embodiments, rather than to limit the scope of the utility model. It must be noted that the singular forms "one", "a kind" and "the" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. Therefore, for example, a reference to "a step" means a reference to one or more steps, and may include secondary steps. All conjunctions used should be understood in the broadest sense. Therefore, the word "or" should be understood to have a logical "or" definition, rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite meaning. The structure described here will be understood to also quote the functional equivalent of the structure. Language that can be interpreted as approximate should be understood that way unless the context clearly indicates the opposite meaning.

Claims

1. A filter, characterized in that: include: a piezoelectric substrate on which interdigital transducer electrodes are disposed; a support layer including an outer peripheral support structure and a plurality of inner support structures, wherein the outer peripheral support structure is disposed on the piezoelectric substrate around the periphery of a region in which the interdigital transducer electrodes are disposed, and the inner support structure is disposed on the piezoelectric substrate below the metal bump and is surrounded by the outer peripheral support structure; A covering layer, located on the supporting layer and surrounding the supporting layer and the piezoelectric substrate to form a cavity; a redistribution layer, located on the cover layer; A plurality of metal bumps are located on the rewiring layer.

2. The filter according to claim 1, characterized in that The internal supporting structure is in the shape of an elongated strip.

3. The filter according to claim 1, characterized in that In a state of planarly viewing the piezoelectric substrate, the peripheral support structure is a rectangular frame.

4. The filter according to claim 3, characterized in that In a state of planarly viewing the piezoelectric substrate, the plurality of internal support structures are parallel to short sides of the rectangular frame.

5. The filter according to claim 4, characterized in that The multiple internal support structures include a first internal support structure and a second internal support structure. When looking down at the piezoelectric substrate, when the ends of the first internal support structure and the second internal support structure in a first direction parallel to the short side of the rectangular frame are set as the first end, and the ends on the opposite side of the first direction are set as the second end, the first end of the first internal support structure contacts the peripheral support structure and the second end does not contact the peripheral support structure, the second end of the second internal support structure contacts the peripheral support structure and the first end does not contact the peripheral support structure, and the gap between the second end of the first internal support structure and the peripheral support structure is larger than the gap between the first end of the second internal support structure and the peripheral support structure.

6. The filter according to claim 3, characterized in that The line width of the rectangular frame is greater than or equal to 30 nm.

7. The filter according to claim 3, characterized in that The length of the internal support structure is shorter than the length of the short side of the rectangular frame.

8. The filter according to claim 1, characterized in that The different internal support structures are arranged on the same horizontal line or on different horizontal lines.

9. The filter according to claim 1, characterized in that The height of the support layer is greater than the height of the interdigital transducer electrode.

10. The filter according to claim 1, characterized in that The height of the inner support structure is the same as the height of the outer peripheral support structure.

11. The filter according to claim 1, characterized in that The metal bump is a solder ball.

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