Filter and preparation method thereof

Abstract

The invention provides a filter and a preparation method thereof. The filter comprises a substrate; the interdigital transducer, the bonding pad metal layer, the passivation layer, the gold ball, the epoxy resin layer and the substrate are sequentially arranged on one side of the substrate from bottom to top; wherein the gold ball is at least partially embedded in the bonding pad metal layer, and one side of the gold ball is in contact with the substrate. The bonding force between a gold ball and a bonding pad metal layer is achieved, and the technical problem of poor ball mounting of the gold ball is effectively solved.

Description

Technical Field

[0001] The present application relates to the field of device packaging technology, and in particular to a filter and a preparation method thereof. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the application that are recited in the claims. The description herein is not admitted to be prior art by inclusion in this section.

[0003] With the rapid development of 4G and 5G communications, RF devices - filters play a core role in the fields of mobile communications and automotive electronics. Therefore, the requirements for the reliability of SAW filter components are getting higher and higher.

[0004] In the prior art, such as Figure 1 The gold ball of the filter shown is welded to the pad metal layer by welding, and the connection between the gold ball and the pad metal layer is surface contact; in actual application, the bonding force between the gold ball and the pad metal layer is weak, and the probability of the gold ball detaching from the pad metal layer is high, thereby affecting the device quality of the filter.

[0005] Based on this, the present application urgently needs to propose a filter and a preparation method thereof that can solve the above technical problems. Summary of the invention

[0006] Multiple aspects of the present application provide a filter and a method for manufacturing the same, so as to improve the stability of the bonding between the gold ball and the pad metal layer of the filter.

[0007] In one aspect of the present application, a filter is provided, the filter comprising:

[0008] substrate;

[0009] An interdigital transducer, a pad metal layer, a passivation layer, a gold ball, an epoxy resin layer and a substrate are sequentially arranged on one side of the substrate from bottom to top;

[0010] The gold ball is at least partially embedded in the pad metal layer, and one side of the gold ball is in contact with the substrate.

[0011] Furthermore, the pad metal layer is at least partially embedded in the interdigital electrode lead-out portion of the interdigital transducer.

[0012] Furthermore, the pad metal layer penetrates through the interdigital electrode lead-out portion of the IDT and is at least partially embedded in the substrate.

[0013] Furthermore, the interdigital electrode lead-out portion of the IDT is at least partially embedded in the substrate.

[0014] Furthermore, at least one first groove is provided on the pad metal layer, so that the gold ball is at least partially embedded in the pad metal layer through the first groove.

[0015] Furthermore, the total area of ​​the projection of the first groove in the first direction is the first projection area; the area of ​​the projection of the pad metal layer in the first direction is the second projection area; and the ratio of the first projection area to the second projection area ranges from 1:6 to 1:2.

[0016] Furthermore, the ratio of the depth of the first groove to the thickness of the pad metal layer is in the range of 1:50 to 2:5.

[0017] Further, the filter further comprises: a PSV layer, disposed between the epoxy resin layer and the pad metal layer, and covering a side of the first passivation layer away from the substrate;

[0018] Wherein, the first passivation layer is a passivation layer covering the interdigital poles of the interdigital transducer.

[0019] Furthermore, the filter further comprises: an FM layer, which is arranged on a side of the first passivation layer away from the substrate and between the passivation layer and the PSV layer.

[0020] Furthermore, the substrate, the epoxy resin layer and the PSV layer define a cavity.

[0021] Furthermore, the substrate, the epoxy resin layer and the passivation layer define a cavity.

[0022] In another aspect, the present application provides a filter preparation method, the filter preparation method comprising:

[0023] providing a substrate;

[0024] An interdigital transducer, a pad metal layer, a passivation layer, a gold ball, an epoxy resin layer and a substrate are sequentially arranged on one side of the substrate from bottom to top.

[0025] The gold ball is at least partially embedded in the pad metal layer, and one side of the gold ball is in contact with the substrate.

[0026] The present application provides a filter and a preparation method thereof, the filter comprising: a substrate; an interdigital transducer, a pad metal layer, a passivation layer, a gold ball, an epoxy resin layer and a substrate arranged in sequence from bottom to top on one side of the substrate; wherein the gold ball is at least partially embedded in the pad metal layer, and one side of the gold ball is in contact with the substrate. The present application adopts a CSP packaging process, and by partially embedding the gold ball into the pad metal layer, the bonding force between the gold ball and the pad metal layer is improved, and the technical problem of poor CSP packaging ball implantation existing in the traditional packaging structure is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0029] Figure 1 It is a structural schematic diagram of a filter in the prior art;

[0030] Figure 2 A schematic diagram of the structure of a filter provided in one embodiment of the present application (I);

[0031] Figure 3 A schematic diagram of the structure of a filter provided in one embodiment of the present application (II);

[0032] Figure 4 A schematic diagram of the structure of a filter provided in one embodiment of the present application (III);

[0033] Figure 5 A schematic diagram of the structure of the first groove, the second groove, the third groove, and the through hole of the filter provided in one embodiment of the present application;

[0034] Figure 6 A schematic diagram of the structure of a filter provided in one embodiment of the present application (IV);

[0035] Figure 7 A schematic diagram of the structure of a filter provided in one embodiment of the present application (V);

[0036] Figure 8 A schematic diagram of a filter preparation method according to an embodiment of the present application;

[0037] Figures 9 to 14A schematic diagram of the structure of a filter preparation process corresponding to a filter preparation method provided in an embodiment of the present application;

[0038] Fig.15 A schematic flow chart of a filter preparation method provided in yet another embodiment of the present application;

[0039] Figure 16-17 A structural schematic diagram of a filter preparation process corresponding to a filter preparation method provided in another embodiment of the present application;

[0040] Fig.18 A schematic flow chart of a filter preparation method provided in another embodiment of the present application;

[0041] Figure 19 to Figure 22 A structural schematic diagram of a filter preparation process corresponding to a filter preparation method provided in yet another embodiment of the present application.

[0042] The reference numerals are as follows:

[0043] 01-substrate; 02-interdigital transducer; 03-pad metal layer; 04-passivation layer; 05-gold ball; 06-epoxy resin layer; 07-base plate; 08-first groove; 09-second groove; 10-fourth groove; 11-through hole; 12-PSV layer; 13-FM layer; 14-third groove.

[0044] The same or similar reference numerals in the drawings represent the same or similar components. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] Embodiment 1

[0047] like Figure 2 As shown, the present application provides a filter, the filter comprising:

[0048] Substrate 01;

[0049] An interdigital transducer 02, a pad metal layer 03, a passivation layer 04, a gold ball 05, an epoxy resin layer 06 and a base plate 07 are sequentially arranged on one side of the substrate 01 from bottom to top;

[0050] The gold ball 05 is at least partially embedded in the pad metal layer 03 , and one side of the gold ball 05 is in contact with the substrate 07 .

[0051] Specifically, the pad metal layer 03 is provided with a first groove 08 , and the gold ball 05 is embedded in the first groove 08 .

[0052] In one embodiment, if Figure 2 As shown, the pad metal layer 03 is at least partially embedded in the interdigital electrode lead-out portion of the IDT 02 ; specifically, the interdigital electrode lead-out portion is provided with a second groove 09 , and the pad metal layer 03 is embedded in the interdigital electrode lead-out portion through the second groove 09 .

[0053] In one embodiment, if Figure 4 The pad metal layer 03 shown passes through the interdigital electrode lead-out portion of the IDT 02 and is at least partially embedded in the substrate 01. Specifically, the interdigital electrode lead-out portion is provided with a through hole 11, a third groove 14 is provided on the substrate 01, and the pad metal layer 03 passes through the through hole 11 and is embedded in the third groove 14.

[0054] In one embodiment, if Figure 3 As shown, the interdigital electrode lead-out portion of the IDT 02 is at least partially embedded in the substrate 01. Specifically, the substrate 01 is provided with a fourth groove 10, and the interdigital electrode lead-out portion is embedded in the fourth groove 10.

[0055] The present application forms a bonding structure between the gold ball 05 and the pad metal layer 03 or the forked electrode lead-out portion by setting a groove on the carrier structure, thereby increasing the contact area between the gold ball 05 and the carrier structure, enhancing the bonding between the two, and improving the structural stability of the filter.

[0056] It should be understood that the present application does not limit the number and structural shape of the first groove 08, the second groove 09, the third groove 14, the fourth groove 10 and the through hole 11. Those skilled in the art can reasonably design and select according to the actual application scenario, as long as the tight bonding between the gold ball 05 and the carrier structure can be achieved. For example, the cross-sectional shape of the groove and the through hole 11 can be rectangular, square, trapezoidal, serrated and arc-shaped. The projection of the groove in the first direction can also include but is not limited to the following: Figure 5 Various shapes shown.

[0057] In one embodiment, the projection area of ​​the first groove 08 in the first direction is the first projection area; the projection area of ​​the pad metal layer 03 in the first direction is the second projection area; the ratio of the first projection area to the second projection area ranges from 1:6 to 1:2.

[0058] In one embodiment, the projection area of ​​the through hole 11 in the first direction is the first projection area; the projection area of ​​the pad metal layer 03 in the first direction is the second projection area; the ratio of the first projection area to the second projection area ranges from 1:6 to 1:2. The first direction described in this application is a direction perpendicular to the plane of the substrate 01.

[0059] In one embodiment, the ratio of the depth of the first groove to the thickness of the pad metal layer is in the range of 1:50 to 2:5. In actual production applications, the thickness of the pad metal layer is 1 micron to 5 microns, and the depth of the first groove is 20 nanometers to 2 microns.

[0060] It should be understood that, when there are multiple first grooves 08 and / or through holes 11, the area of ​​the projection of the first groove 08 in one direction should be the sum of the areas of the projections of the multiple first grooves 08 in the first direction; similarly, the area of ​​the projection of the through hole 11 in the first direction should also be the sum of the areas of the projections of the multiple through holes 11 in the first direction.

[0061] In one embodiment, the substrate 07 , the first passivation layer and the epoxy resin layer 06 define a cavity; the first passivation layer includes a passivation layer 04 covering the interdigital poles of the IDT 02 .

[0062] In one embodiment, the passivation layer 04 further includes a second passivation layer, and the second passivation layer covers the non-contact area between the IDT 02 and the pad metal layer 03 , and the non-contact area between the pad metal layer 03 and the gold ball 05 .

[0063] In one embodiment, the material of the passivation layer 04 includes but is not limited to silicon nitride or silicon oxide.

[0064] Embodiment 2

[0065] The present application proposes a filter, which comprises:

[0066] Substrate 01;

[0067] An interdigital transducer 02, a pad metal layer 03, a passivation layer 04, a gold ball 05, an epoxy resin layer 06 and a base plate 07 are sequentially arranged on one side of the substrate 01 from bottom to top;

[0068] The gold ball 05 is at least partially embedded in the pad metal layer 03 , and one side of the gold ball 05 is in contact with the substrate 07 .

[0069] Specifically, the pad metal layer 03 is provided with a first groove 08 , and the gold ball 05 is embedded in the first groove 08 .

[0070] In one embodiment, the pad metal layer 03 is at least partially embedded in the interdigital electrode lead-out portion of the IDT 02 ; specifically, the interdigital electrode lead-out portion is provided with a second groove 09 , and the pad metal layer 03 is embedded in the interdigital electrode lead-out portion through the second groove 09 .

[0071] In one embodiment, the pad metal layer 03 penetrates the interdigital electrode lead-out portion of the IDT 02 and is at least partially embedded in the substrate 01. Specifically, the interdigital electrode lead-out portion is provided with a through hole 11, a third groove 14 is provided on the substrate 01, and the pad metal layer 03 penetrates the through hole 11 and is embedded in the third groove 14.

[0072] In one embodiment, the interdigital electrode lead-out portion of the IDT 02 is at least partially embedded in the substrate 01. Specifically, the substrate 01 is provided with a fourth groove 10, and the interdigital electrode lead-out portion is embedded in the fourth groove 10.

[0073] The present application forms a bonding structure between the gold ball 05 and the pad metal layer 03 or the forked electrode lead-out portion by setting a groove on the carrier structure, thereby increasing the contact area between the gold ball 05 and the carrier structure, enhancing the bonding between the two, and improving the structural stability of the filter.

[0074] It should be understood that the present application does not limit the number and structural shape of the first groove 08, the second groove 09, the third groove 14, the fourth groove 10 and the through hole 11. Those skilled in the art can reasonably design and select according to the actual application scenario, as long as the tight bonding between the gold ball 05 and the carrier structure can be achieved. For example, the cross-sectional shape of the groove and the through hole 11 can be rectangular, square, trapezoidal, serrated and arc-shaped. The projection of the groove in the first direction can also include but is not limited to the following: Figure 5 Various shapes shown.

[0075] In one embodiment, the projection area of ​​the first groove 08 in the first direction is the first projection area; the projection area of ​​the pad metal layer 03 in the first direction is the second projection area; the ratio of the first projection area to the second projection area ranges from 1:6 to 1:2.

[0076] In one embodiment, the projection area of ​​the through hole 11 in the first direction is the first projection area; the projection area of ​​the pad metal layer 03 in the first direction is the second projection area; the ratio of the first projection area to the second projection area ranges from 1:6 to 1:2. The first direction described in this application is a direction perpendicular to the plane of the substrate 01.

[0077] It should be understood that, when there are multiple first grooves 08 and / or through holes 11, the area of ​​the projection of the first groove 08 in one direction should be the sum of the areas of the projections of the multiple first grooves 08 in the first direction; similarly, the area of ​​the projection of the through hole 11 in the first direction should also be the sum of the areas of the projections of the multiple through holes 11 in the first direction.

[0078] In one embodiment, the ratio of the depth of the first groove to the thickness of the pad metal layer is in the range of 1:50 to 2:5. In actual production applications, the thickness of the pad metal layer is 1 micron to 5 microns, and the depth of the first groove is 20 nanometers to 2 microns.

[0079] In one embodiment, if Figure 6 As shown, the filter further includes: a PSV layer 12, which is disposed between the epoxy resin layer 06 and the pad metal layer 03, and covers the side of the first passivation layer away from the substrate 01; wherein the first passivation layer includes a passivation layer 04 covering the interdigital poles of the interdigital transducer 02.

[0080] In one embodiment, the passivation layer 04 further includes a third passivation layer, and the third passivation layer covers a portion of a non-contact area between the IDT 02 and the pad metal layer 03 .

[0081] In one embodiment, the substrate 07 , the first passivation layer and the PSV layer 12 define a cavity.

[0082] In one embodiment, the material of the passivation layer 04 includes but is not limited to silicon nitride or silicon oxide.

[0083] Embodiment 3

[0084] The present application proposes a filter, which comprises:

[0085] Substrate 01;

[0086] An interdigital transducer 02, a pad metal layer 03, a passivation layer 04, a gold ball 05, an epoxy resin layer 06 and a base plate 07 are sequentially arranged on one side of the substrate 01 from bottom to top;

[0087] The gold ball 05 is at least partially embedded in the pad metal layer 03 , and one side of the gold ball 05 is in contact with the substrate 07 .

[0088] Specifically, the pad metal layer 03 is provided with a first groove 08 , and the gold ball 05 is embedded in the first groove 08 .

[0089] In one embodiment, the pad metal layer 03 is at least partially embedded in the interdigital electrode lead-out portion of the IDT 02 ; specifically, the interdigital electrode lead-out portion is provided with a second groove 09 , and the pad metal layer 03 is embedded in the interdigital electrode lead-out portion through the second groove 09 .

[0090] In one embodiment, the pad metal layer 03 penetrates the interdigital electrode lead-out portion of the IDT 02 and is at least partially embedded in the substrate 01. Specifically, the interdigital electrode lead-out portion is provided with a through hole 11, a third groove 14 is provided on the substrate 01, and the pad metal layer 03 penetrates the through hole 11 and is embedded in the third groove 14.

[0091] In one embodiment, the interdigital electrode lead-out portion of the IDT 02 is at least partially embedded in the substrate 01. Specifically, the substrate 01 is provided with a fourth groove 10, and the interdigital electrode lead-out portion is embedded in the fourth groove 10.

[0092] The present application forms a bonding structure between the gold ball 05 and the pad metal layer 03 or the forked electrode lead-out portion by setting a groove on the carrier structure, thereby increasing the contact area between the gold ball 05 and the carrier structure, enhancing the bonding between the two, and improving the structural stability of the filter.

[0093] It should be understood that the present application does not limit the number and structural shape of the first groove 08, the second groove 09, the third groove 14, the fourth groove 10 and the through hole 11. Those skilled in the art can reasonably design and select according to the actual application scenario, as long as the tight bonding between the gold ball 05 and the carrier structure can be achieved. For example, the cross-sectional shape of the groove and the through hole 11 can be rectangular, square, trapezoidal, serrated and arc-shaped. The projection of the groove in the first direction can also include but is not limited to the following: Figure 5 Various shapes shown.

[0094] In one embodiment, the projection area of ​​the first groove 08 in the first direction is the first projection area; the projection area of ​​the pad metal layer 03 in the first direction is the second projection area; the ratio of the first projection area to the second projection area ranges from 1:6 to 1:2.

[0095] In one embodiment, the projection area of ​​the through hole 11 in the first direction is the first projection area; the projection area of ​​the pad metal layer 03 in the first direction is the second projection area; the ratio of the first projection area to the second projection area ranges from 1:6 to 1:2. The first direction described in this application is a direction perpendicular to the plane of the substrate 01.

[0096] It should be understood that, when there are multiple first grooves 08 and / or through holes 11, the area of ​​the projection of the first groove 08 in one direction should be the sum of the areas of the projections of the multiple first grooves 08 in the first direction; similarly, the area of ​​the projection of the through hole 11 in the first direction should also be the sum of the areas of the projections of the multiple through holes 11 in the first direction.

[0097] In one embodiment, the ratio of the depth of the first groove to the thickness of the pad metal layer is in the range of 1:50 to 2:5. In actual production applications, the thickness of the pad metal layer is 1 micron to 5 microns, and the depth of the first groove is 20 nanometers to 2 microns.

[0098] In one embodiment, if Figure 7 As shown, the filter includes an FM layer 13 disposed on a side of the first passivation layer facing away from the substrate 01 ; wherein the first passivation layer includes a side covering the interdigital poles of the interdigital transducer 02 .

[0099] In one embodiment, the filter includes a PSV layer 12 disposed on the side of the FM layer 13 facing away from the substrate 01 and a fourth passivation layer; wherein the fourth passivation layer is a passivation layer 04 without the FM layer 13 and a passivation layer 04 not covered with gold balls 05 .

[0100] In one embodiment, the substrate 07 , the PSV layer 12 and the epoxy resin layer 06 define a cavity.

[0101] Embodiment 4

[0102] like Figure 8 As shown, the present application provides a filter preparation method corresponding to the filter described in any one of Embodiment 1, Embodiment 2 and Embodiment 3, and the method includes:

[0103] Step S401, providing a substrate 01;

[0104] Step S402, sequentially disposing an interdigital transducer 02, a pad metal layer 03 and a passivation layer 04 on one side of the substrate 01 from bottom to top;

[0105] Step S403, etching the passivation layer 04 and the pad metal layer 03 to form a first groove 08;

[0106] Step S404, arranging the gold ball 05 to the first groove 08, so that part of the gold ball 05 is embedded in the pad metal layer 03 through the first groove 08;

[0107] Step S405 , forming an epoxy resin layer 06 and a base plate 07 on the side of the gold ball 05 facing away from the substrate 01 .

[0108] In one embodiment, the filter preparation method further includes: etching the interdigital electrode lead-out portion of the IDT 02 to form a second groove 09 , so that a portion of the pad metal layer 03 is embedded in the interdigital electrode lead-out portion through the second groove 09 .

[0109] In one embodiment, the filter manufacturing method further includes: etching the substrate 01 to form a third groove 14 , so that a portion of the interdigital electrode lead-out portion of the IDT 02 is embedded in the substrate 01 through the third groove 14 .

[0110] In one embodiment, the filter preparation method further includes: etching the interdigital electrode lead-out portion of the interdigital transducer 02 to form a through hole 11, and etching the substrate 01 to form a fourth groove 10, so that a portion of the pad metal layer 03 passes through the through hole 11 and is embedded in the substrate 01 through the fourth groove 10.

[0111] The structural schematic diagrams of the steps in the filter preparation process of the filter preparation method described in this embodiment are as follows: Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 , Fig.14 .

[0112] Based on the filter preparation method proposed in this embodiment, the technical effect of improving the stable bonding between the gold ball 05 and the pad metal layer 03 and thus improving the reliability and stability of the overall device can be achieved without changing the packaging structure and packaging process of the filter.

[0113] Embodiment 5

[0114] like Fig.15 As shown, this embodiment provides a filter preparation method for preparing the filter proposed in Embodiment 2, the method comprising:

[0115] Step S501, providing a substrate 01;

[0116] Step S502, sequentially disposing an IDT 02, a pad metal layer 03 and a passivation layer 04 on one side of the substrate 01 from bottom to top;

[0117] Step S503, etching the passivation layer 04 and the pad metal layer 03 to form a first groove 08;

[0118] Step S504, forming a PSV layer 12 on the sidewall of the pad metal layer 03 of the carrier structure and the side of the passivation layer 04 facing away from the substrate 01;

[0119] Step S505, bonding the alloy ball 05 to the first groove 08;

[0120] Step S506 , disposing a substrate 07 on the side of the gold ball 05 away from the substrate 01 , and coating the sidewalls of the gold ball 05 and the PSV layer 12 with an epoxy gold layer.

[0121] In one embodiment, the filter preparation method further includes: etching the interdigital electrode lead-out portion of the IDT 02 to form a second groove 09 , so that a portion of the pad metal layer 03 is embedded in the interdigital electrode lead-out portion through the second groove 09 .

[0122] In one embodiment, the filter manufacturing method further includes: etching the substrate 01 to form a third groove 14 , so that a portion of the interdigital electrode lead-out portion of the IDT 02 is embedded in the substrate 01 through the third groove 14 .

[0123] In one embodiment, the filter preparation method further includes: etching the interdigital electrode lead-out portion of the interdigital transducer 02 to form a through hole 11, and etching the substrate 01 to form a fourth groove 10, so that a portion of the pad metal layer 03 passes through the through hole 11 and is embedded in the substrate 01 through the fourth groove 10.

[0124] The structural schematic diagrams of the steps in the filter preparation process of the filter preparation method described in this embodiment are as follows: Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.16 , Fig.17 .

[0125] Embodiment 6

[0126] like Fig.18 As shown, this embodiment provides a filter preparation method for preparing the filter proposed in Embodiment 3, the method comprising:

[0127] Step S601, providing a substrate 01;

[0128] Step S602, sequentially disposing an IDT 02, a pad metal layer 03 and a passivation layer 04 on one side of the substrate 01 from bottom to top;

[0129] Step S603, etching the passivation layer 04 and the pad metal layer 03 to form a first groove 08;

[0130] Step S604, forming an FM layer 13 on a side of the first passivation layer away from the substrate 01;

[0131] Step S605, forming a PSV layer 12 on a side of the FM layer 13 facing away from the substrate 01 and at least a portion of a side of the passivation layer 04 facing away from the substrate 01;

[0132] Step S606, bonding the alloy ball 05 to the first groove 08;

[0133] Step S607 , disposing a substrate 07 on the side of the gold ball 05 away from the substrate 01 , and coating the sidewalls of the gold ball 05 and the PSV layer 12 with an epoxy gold layer.

[0134] In one embodiment, the filter preparation method further includes: etching the interdigital electrode lead-out portion of the IDT 02 to form a second groove 09 , so that a portion of the pad metal layer 03 is embedded in the interdigital electrode lead-out portion through the second groove 09 .

[0135] In one embodiment, the filter manufacturing method further includes: etching the substrate 01 to form a third groove 14 , so that a portion of the interdigital electrode lead-out portion of the IDT 02 is embedded in the substrate 01 through the third groove 14 .

[0136] In one embodiment, the filter preparation method further includes: etching the interdigital electrode lead-out portion of the interdigital transducer 02 to form a through hole 11, and etching the substrate 01 to form a fourth groove 10, so that a portion of the pad metal layer 03 passes through the through hole 11 and is embedded in the substrate 01 through the fourth groove 10.

[0137] The structural schematic diagrams of the steps in the filter preparation process of the filter preparation method described in this embodiment are as follows: Fig. 9 , Fig.10 , Fig.11 , Fig.19 , Fig. 20 , Fig.21 , Fig. 22 .

[0138] It should be understood that the substrate 01 mentioned in any embodiment of the present application includes but is not limited to a lithium tantalate (LT) substrate, a lithium niobate (LN) substrate, a POI substrate (prepared using a Smart-Cut process, consisting of a thin layer of piezoelectric single crystal material (such as single crystal lithium tantalate / lithium niobate), a silicon dioxide layer and a high-resistance silicon substrate), a Bonding substrate, etc.

[0139] It should also be understood that the filters described in the present application include but are not limited to surface acoustic wave filters (full name in English: Surface Acoustic Wave Filter; abbreviated as: SAWF or SAW filter), temperature compensated surface acoustic wave filters (full name in English: Temperature Compensated Surface Acoustic Wave Filter; abbreviated as: TC-SAW) and thin film surface acoustic wave filters (full name in English: Thin-Film Surface Acoustic Wave; abbreviated as: TF-SAW).

[0140] Embodiment 7

[0141] This embodiment provides a MEMS device, which at least includes the filter described in any one of Embodiments 1 to 3.

[0142] In one implementation manner, the filter described in any one of Embodiments 1 to 3 is prepared by using the filter preparation method described in any one of Embodiments 4 to 6.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

[0144] In addition, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in a device claim can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

Claims

1. A filter, characterized in that: The filter comprises: substrate; An interdigital transducer, a pad metal layer, a passivation layer, a gold ball, an epoxy resin layer and a substrate are sequentially arranged on one side of the substrate from bottom to top; The gold ball is at least partially embedded in the pad metal layer, and one side of the gold ball is in contact with the substrate.

2. The filter according to claim 1, characterized in that The pad metal layer is at least partially embedded in the interdigital electrode lead-out portion of the interdigital transducer.

3. The filter according to claim 1, characterized in that The pad metal layer penetrates through the interdigital electrode lead-out portion of the IDT and is at least partially embedded in the substrate.

4. The filter according to any one of claims 1 to 3, characterized in that: The interdigital electrode lead-out portion of the IDT is at least partially embedded in the substrate.

5. The filter according to any one of claims 1 to 3, characterized in that: At least one first groove is provided on the pad metal layer, so that the gold ball is at least partially embedded in the pad metal layer through the first groove.

6. The filter according to claim 5, characterized in that The total area of ​​the projection of the first groove in the first direction is the first projection area; The projection area of ​​the pad metal layer in the first direction is the second projection area; The ratio of the first projection area to the second projection area ranges from 1:6 to 1:

2.

7. The filter according to claim 6, characterized in that The ratio of the depth of the first groove to the thickness of the pad metal layer is in the range of 1:50 to 2:

5.

8. The filter according to claim 7, characterized in that The filter further comprises: A PSV layer is disposed between the epoxy resin layer and the pad metal layer, and covers a side of the first passivation layer away from the substrate; Wherein, the first passivation layer is a passivation layer covering the interdigital poles of the interdigital transducer.

9. The filter according to claim 7, characterized in that The filter further comprises: The FM layer is disposed on a side of the first passivation layer facing away from the substrate and between the passivation layer and the PSV layer.

10. The filter according to claim 8 or 9, characterized in that: The substrate, the epoxy resin layer and the PSV layer define a cavity.

11. The filter according to claim 7, characterized in that The substrate, the epoxy resin layer and the passivation layer define a cavity.

12. A filter preparation method, characterized in that: The filter preparation method comprises: providing a substrate; An interdigital transducer, a pad metal layer, a passivation layer, a gold ball, an epoxy resin layer and a substrate are sequentially arranged on one side of the substrate from bottom to top. The gold ball is at least partially embedded in the pad metal layer, and one side of the gold ball is in contact with the substrate.

Images