Thickness-integrated structure for surface acoustic wave filter and method for manufacturing the same

Abstract

The application discloses a thickness integrated structure for a surface acoustic wave filter, comprising a body, wherein the body comprises a packaging substrate and at least two chips stacked in sequence along a thickness direction on the packaging substrate through a bonding layer; and a pad of each chip is electrically connected with a pad of the packaging substrate through a conductive channel structure. The application further discloses a manufacturing method of the thickness integrated structure for the surface acoustic wave filter. The application integrates chips such as the surface acoustic wave filter in the thickness direction, thereby reducing the surface area of the device and saving the internal space of a mobile phone.

Description

Technical Field

[0001] This invention belongs to the field of electronic device technology, specifically relating to a thickness-integrated structure that can be used in surface acoustic wave filters and its fabrication method. Background Technology

[0002] SAW (surface acoustic wave) is an elastic wave generated and propagating on the surface of a piezoelectric substrate, with its amplitude decreasing rapidly with increasing depth into the substrate. Existing SAW filters, when used for multi-channel applications, either employ multiple separate SAW devices or use duplexers or multiplexers. A duplexer or multiplexer uses multiple filters on a separate chip or a single substrate within the same package to achieve multi-channel filtering. Related packaging methods all increase surface area to process multi-channel signals. With the increasing number of channels in mobile phones and the significant increase in filter usage, this drastically increases the surface area occupied by the internal PCB, reducing the space available for other functional chips and increasing the design complexity of the phone. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a surface acoustic wave filter thickness integration structure and its fabrication method that can save internal space in mobile phones.

[0004] In a first aspect, a thickness-integrated structure for use in surface acoustic wave filters includes a body, the body comprising a packaging substrate and at least two chips stacked sequentially along the thickness direction on the packaging substrate by bonding layers.

[0005] The pads of each chip are electrically connected to the pads of the packaging substrate through a conductive channel structure.

[0006] In one embodiment, the conductive channel structure is located inside the body; the conductive channel structure between each chip that is not adjacent to the packaging substrate and the packaging substrate extends through all chips between them.

[0007] In one embodiment, the conductive channel structure includes a through hole located inside the body and a conductive material disposed within the through hole for establishing an electrical connection.

[0008] In one embodiment, the conductive channel structure is located on the body side surface.

[0009] In one embodiment, the conductive channel structure includes a groove located on the side surface of the body and a conductive material disposed within the groove for establishing an electrical connection.

[0010] Secondly, a method for fabricating a thickness-integrated structure that can be used in surface acoustic wave (SAW) filters includes:

[0011] A packaging substrate and a wafer are provided, wherein multiple chips are fabricated on the wafer; there are at least two wafers, including a bottom wafer and a top wafer;

[0012] Through-holes are fabricated and metallized on the packaging substrate to obtain packaging substrate pads. The number of packaging substrate pads or through-holes corresponds to the number of chip pads of all chips that should be integrated on the packaging substrate.

[0013] Vias are fabricated and metallized on wafers other than the top wafer, wherein the number of vias on any wafer corresponds to the number of chip pads of all chips that should be integrated on top of that chip;

[0014] A bonding layer is fabricated on all wafers and the packaging substrate, and the bonding material on the bonding layer corresponding to the acoustic channel region is removed;

[0015] The packaging substrate and all wafers are aligned and bonded to form a wafer stack structure, wherein the vias on each wafer in the wafer stack structure are aligned to form a conductive channel structure for electrical connection to the pads on the packaging substrate.

[0016] The wafer stacking structure is diced to obtain a body corresponding to the number of chips on the wafer.

[0017] Methods for fabricating thick integrated structures that can be used in surface acoustic wave (SAW) filters include:

[0018] A packaging substrate and a wafer are provided, wherein multiple chips are fabricated on the wafer; there are at least two wafers, including a bottom wafer and a top wafer;

[0019] A bonding layer is fabricated on all wafers and the packaging substrate, and the bonding material on the bonding layer corresponding to the acoustic channel region is removed;

[0020] The packaging substrate and all wafers are aligned and bonded to form a wafer stack structure;

[0021] The wafer stacking structure is diced to obtain a body corresponding to the number of chips on the wafer;

[0022] Conductive channel structures are formed on the side of the main body to electrically connect the chip pads of each chip on the main body with the corresponding pads of the packaging substrate.

[0023] In one embodiment, the step of fabricating a conductive channel structure on the side of the body to electrically connect the chip pads of each chip on the body with the corresponding pads of the packaging substrate includes:

[0024] A groove is made between the chip pad position of each chip and the corresponding packaging substrate pad position on the side of the body.

[0025] A conductive material for establishing an electrical connection is provided within the groove.

[0026] In one embodiment, when the bonding material of the bonding layer is metal, the bonding material corresponding to the wiring area on the bonding layer is removed, or an insulating layer is added to the wiring area.

[0027] In one embodiment, the cross-section of the groove is semi-circular, rectangular, or trapezoidal.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] By integrating chips such as surface acoustic wave filters into the thickness, the surface area of ​​the device can be reduced, thereby saving internal space in the mobile phone. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the thickness integrated structure that can be used in surface acoustic wave filters in this invention;

[0032] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the thickness integrated structure that can be used in surface acoustic wave filters in this invention;

[0033] Figure 3 This is a schematic diagram of the AA cross-section of Embodiment 2 of the thickness integrated structure that can be used in surface acoustic wave filters in this invention;

[0034] Figure 4 This is a schematic flowchart of one embodiment of the method for fabricating a thickness-integrated structure that can be used in surface acoustic wave filters according to the present invention.

[0035] Figure 5 This is a schematic flowchart of another embodiment of the method for fabricating a thickness-integrated structure that can be used in surface acoustic wave filters according to the present invention;

[0036] Among them, 1. Packaging substrate; 2. Bottom chip; 3. Top chip; 4. Bonding layer; 41. First bonding layer; 42. Second bonding layer; 5. Through hole; 51. First through hole; 52. Second through hole; 6. Conductive material; 7. Pad; 71. Chip pad; 72. Packaging substrate pad; 8. Groove; 81. First groove; 82. Second groove. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0038] The terminology used in this application is for the purpose of describing specific embodiments only and is not intended to limit the application. In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application, unless otherwise expressly specified and limited, "above" or "below" a second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. Exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments and implementations can complement or combine with each other.

[0041] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this application are described clearly and completely below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0043] First aspect, Example 1: as follows Figure 1 As shown, a thickness-integrated structure that can be used for surface acoustic wave (SAW) filters includes a body, comprising:

[0044] Packaging substrate 1;

[0045] The underlying chip 2 is located on the packaging substrate 1 and is bonded to the packaging substrate 1 through the first bonding layer 41;

[0046] A top-level chip 3 located on the bottom-level chip 2 and bonded to the bottom-level chip 2 via a second bonding layer 42;

[0047] The packaging substrate 1 and the bottom chip 2 are provided with through holes 5. The through holes 5 include a first through hole 51 connecting to the lower side of the bottom chip 2 and a second through hole 52 connecting to the lower side of the top chip 3. The through holes 5 are provided with conductive material 6 for establishing electrical connections. The conductive material 6 in the through holes 5 is used to establish electrical connections between the chip pads 71 ​​and the packaging substrate pads 72.

[0048] The chip includes at least a chip with a filter, and may also include various functional chips such as switches, power amplifiers (PAs), low-noise amplifiers (LNAs), and channel filters. The vias can be fabricated by etching or physical drilling. The conductive material can be a metal, such as Cu or Au; the conductive material can be deposited within the vias by chemical plating or electroplating. The bonding materials for the first and second bonding layers can be gold, silver, tin, silicon, silicon dioxide, adhesives, etc. When the bonding material of the bonding layer is a metal, the bonding material corresponding to the wiring area on the bonding layer must be removed, or an insulating layer must be added to the wiring area.

[0049] The packaging substrate and the chips are bonded together, and the chips are connected to each other using bonding layers. Multiple chips can be stacked sequentially along the thickness direction of the packaging substrate through the bonding layers. The number of stacked chips is at least two, such as the bottom chip and the top chip in this embodiment, and several other chips can also be placed between them. The second via can be formed by connecting a via portion that penetrates the packaging substrate (i.e., connects the bottom side of the packaging substrate to the bottom side of the bottom chip) and a via portion that penetrates the bottom chip (i.e., connects the bottom side of the bottom chip to the bottom side of the top chip). If more chips are stacked, the same principle applies.

[0050] In this embodiment, internal metallized vias are used as conductive channels connecting the chip pads and the packaging substrate pads, enabling the integration of chips, such as surface acoustic wave filters, in the thickness direction. This reduces the surface area of ​​the device, thereby saving internal space in the mobile phone. Furthermore, since the metallized vias are placed inside the device, contact with the outside world is reduced, resulting in high reliability.

[0051] Example 2: As Figure 2-3 As shown, a thickness-integrated structure that can be used for surface acoustic wave (SAW) filters includes a body, comprising:

[0052] Packaging substrate 1;

[0053] The underlying chip 2 is located on the packaging substrate 1 and is bonded to the packaging substrate through the first bonding layer 41;

[0054] A top-level chip 3 located on the bottom-level chip 2 and bonded to the bottom-level chip 2 via a second bonding layer 42;

[0055] The outer sides of the packaging substrate 1 and the bottom chip 2 are provided with grooves 8. The grooves 8 include a first groove 81 communicating with the lower side of the bottom chip 2 and a second groove 82 communicating with the lower side of the top chip 3. The grooves 8 are provided with conductive material 6 for establishing electrical connections. The conductive material 6 in the grooves 8 is used to establish electrical connections between the chip pads 71 ​​and the packaging substrate pads 72.

[0056] The chip includes at least a chip with a filter, and may also include various functional chips such as switches, power amplifiers (PAs), low-noise amplifiers (LNAs), and channel filters. The grooves can be fabricated by etching or physical slotting. The conductive material can be a metal, such as a metal that is not easily oxidized, like Au or W; if an easily oxidized metal is used, it may require anti-oxidation treatment. The conductive material can be deposited in the grooves by chemical plating or electroplating.

[0057] The packaging substrate and the chips are bonded together, and the chips themselves are connected via bonding layers. Multiple chips can be stacked sequentially along the thickness direction of the packaging substrate using bonding layers. The number of stacked chips is at least two, such as the bottom chip and the top chip in this embodiment, and several other chips can also be placed between them. The second groove can be obtained by etching or slotting on the corresponding sides of the packaging substrate, the first bonding layer, and the bottom chip. This process continues if more chips are stacked. The shape of the groove can be semi-circular, square, trapezoidal, etc., and can be selected as needed.

[0058] In this embodiment, a metallized groove located at the edge of the device body is used as a conductive channel structure connecting the chip pads and the packaging substrate pads. This enables the integration of chips, such as surface acoustic wave filters, in the thickness direction, reducing the surface area of ​​the device and thus saving internal space in the mobile phone. Compared to the solution in Embodiment 1, there is no need for internal openings, the filter size can be made smaller, the density of the conductive channel structure can be made higher, and more layers of chips can be stacked. Regarding the potential oxidation problem when using metal as a conductive material, one option is to use a metal that is not easily oxidized, and another option is to perform anti-oxidation treatment on it.

[0059] Secondly, one embodiment, such as Figure 4 As shown, a method for fabricating a thickness-integrated structure that can be used for surface acoustic wave (SAW) filters includes the following steps:

[0060] Step 1: Provide a packaging substrate 1 and a wafer, on which multiple chips are fabricated; there are at least two wafers, including a bottom wafer and a top wafer;

[0061] Step 2: Form through holes 5 on the packaging substrate 1 and perform metallization treatment to obtain packaging substrate pads 72. The number of packaging substrate pads 72 or through holes 5 corresponds to the number of chip pads 71 ​​of all chips that should be integrated on the packaging substrate 1.

[0062] Step 3: Fabricate and metallize vias 5 on wafers other than the top wafer, wherein the number of vias 5 on any wafer corresponds to the number of chip pads 71 ​​of all chips to be integrated on the chip above it;

[0063] Step 4: Fabricate bonding layer 4 on all wafers and the packaging substrate 1, and remove the bonding material on the bonding layer 4 corresponding to the acoustic channel region.

[0064] Step 5: Align and bond the packaging substrate 1 and all wafers to form a wafer stack structure. In the wafer stack structure, the vias 5 on each wafer are aligned to form a conductive channel structure for electrical connection to the pads 72 on the packaging substrate.

[0065] Step 6: As Figure 1 As shown, the wafer stacking structure is diced to obtain a body corresponding to the number of chips on the wafer.

[0066] The fabrication method in this embodiment corresponds to that in Embodiment 1. Steps 2 and 3 are not sequential. When the bonding material of the bonding layer is metal, it is also necessary to remove the bonding material on the bonding layer corresponding to the wiring area, or to add an insulating layer on the wiring area.

[0067] Another embodiment, such as Figure 5 As shown, a method for fabricating a thickness-integrated structure that can be used for surface acoustic wave (SAW) filters includes the following steps:

[0068] Step 1: Provide a packaging substrate 1 and a wafer, on which multiple chips are fabricated; there are at least two wafers, including a bottom wafer and a top wafer;

[0069] Step 2: Fabricate bonding layer 4 on all wafers and the packaging substrate 1, and remove the bonding material on the bonding layer 4 corresponding to the acoustic channel region.

[0070] Step 3: Align and bond the packaging substrate 1 and all wafers to form a wafer stack structure;

[0071] Step 4: Divide the wafer stacking structure to obtain a body corresponding to the number of chips on the wafer;

[0072] Step 5: As Figure 2-3 As shown, a conductive channel structure is formed on the side of the main body to electrically connect the chip pads 71 ​​of each chip on the main body with the corresponding pads 72 of the packaging substrate.

[0073] The fabrication method in this embodiment corresponds to that in Embodiment 2. When the bonding material of the bonding layer is metal, the bonding material corresponding to the wiring area on the bonding layer must be removed, or an insulating layer must be added to the wiring area.

[0074] In one embodiment, the step of fabricating a conductive channel structure on the side of the body to electrically connect the chip pads 71 ​​of each chip on the body with the corresponding pads 72 of the packaging substrate may include the following steps:

[0075] Step 51: Create a groove 8 between the chip pad 71 position of each chip and the corresponding packaging substrate pad 72 position on the side of the body;

[0076] Step 52: A conductive material 6 for establishing an electrical connection is provided in the groove 8.

[0077] The technical solution in this invention can be used not only to manufacture surface acoustic wave devices, but also to manufacture other electronic devices, especially in environments with high space utilization requirements.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A thickness-integrated structure that can be used in surface acoustic wave (SAW) filters, characterized in that, The body includes a packaging substrate and at least two chips stacked sequentially along the thickness direction on the packaging substrate by bonding layers. Each of the chip's pads is electrically connected to the pads of the packaging substrate via a conductive channel structure. The conductive channel structure is located inside the body; the conductive channel structure between each chip that is not adjacent to the packaging substrate and the packaging substrate extends through all chips between them. The conductive channel structure includes a through hole located inside the body and a conductive material disposed within the through hole for establishing an electrical connection. The packaging substrate and the bottom chip are provided with through holes, including a first through hole that connects to the bottom side of the bottom chip and a second through hole that connects to the bottom side of the top chip. The second via can be formed by connecting a via portion that penetrates the packaging substrate, i.e., connects the lower side of the packaging substrate to the lower side of the bottom chip, and a via portion that penetrates the bottom chip, i.e. connects the lower side of the bottom chip to the lower side of the top chip. The through-hole contains a conductive material for establishing an electrical connection; the conductive material in the through-hole is used to establish an electrical connection between the chip pad and the packaging substrate pad.

2. The thickness-integrated structure for use in surface acoustic wave filters as described in claim 1, characterized in that: The conductive channel structure includes a groove located on the side surface of the body and a conductive material disposed within the groove for establishing an electrical connection.

3. A method for fabricating a thick integrated structure that can be used in surface acoustic wave filters, applied to the thick integrated structure according to any one of claims 1 to 2, characterized in that, include: A packaging substrate and a wafer are provided, wherein multiple chips are fabricated on the wafer; there are at least two wafers, including a bottom wafer and a top wafer; Through-holes are fabricated and metallized on the packaging substrate to obtain packaging substrate pads. The number of packaging substrate pads or through-holes corresponds to the number of chip pads of all chips that should be integrated on the packaging substrate. Vias are fabricated and metallized on wafers other than the top wafer, wherein the number of vias on any wafer corresponds to the number of chip pads of all chips that should be integrated on top of that chip; A bonding layer is fabricated on all wafers and the packaging substrate, and the bonding material on the bonding layer corresponding to the acoustic channel region is removed; The packaging substrate and all wafers are aligned and bonded to form a wafer stack structure, wherein the vias on each wafer in the wafer stack structure are aligned to form a conductive channel structure for electrical connection to the pads on the packaging substrate. The wafer stacking structure is diced to obtain a body corresponding to the number of chips on the wafer.

4. A method for fabricating a thickness-integrated structure that can be used in surface acoustic wave (SAW) filters, characterized in that, include: A packaging substrate and a wafer are provided, wherein multiple chips are fabricated on the wafer; there are at least two wafers, including a bottom wafer and a top wafer; A bonding layer is fabricated on all wafers and the packaging substrate, and the bonding material on the bonding layer corresponding to the acoustic channel region is removed; The packaging substrate and all wafers are aligned and bonded to form a wafer stack structure; The wafer stacking structure is diced to obtain a body corresponding to the number of chips on the wafer; Conductive channel structures are formed on the side of the main body to electrically connect the chip pads of each chip on the main body with the corresponding pads of the packaging substrate.

5. The method for fabricating a thickness-integrated structure for surface acoustic wave filters as described in claim 4, characterized in that: The method of fabricating a conductive channel structure on the side of the body to electrically connect the chip pads of each chip on the body with the corresponding pads of the packaging substrate includes: A groove is made between the chip pad position of each chip and the corresponding packaging substrate pad position on the side of the body. A conductive material for establishing an electrical connection is provided within the groove.

6. The method for fabricating a thickness-integrated structure for surface acoustic wave filters as described in claim 4, characterized in that: When the bonding material of the bonding layer is metal, the bonding material corresponding to the wiring area on the bonding layer must be removed, or an insulating layer must be added to the wiring area.

7. The method for fabricating the thickness integrated structure for surface acoustic wave (SAW) filters as described in claim 2 or the thickness integrated structure for SAW filters as described in claim 5, characterized in that: The cross-section of the groove is semi-circular, rectangular, or trapezoidal.

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