Bottom electrode excited type surface acoustic wave device structure

Abstract

The application relates to a bottom electrode excitation type surface acoustic wave device structure, which comprises a supporting substrate layer, an insulating layer and a piezoelectric material layer; the supporting substrate layer is provided with the insulating layer, the thickness of the insulating layer is smaller than that of the supporting substrate layer, the piezoelectric material layer is arranged on the insulating layer, the insulating layer is provided with an interdigital transducer structure and an input / output electrode structure at intervals, the input / output electrode structure connecting end extends out of the piezoelectric material layer or the supporting substrate layer and forms a solder ball or a solder spot, and the solder ball or the solder spot is located on the surface of the supporting substrate layer or the surface of the piezoelectric material layer. The application can effectively reduce the influence of the external environment on the surface acoustic wave device, can realize temperature compensation to control the temperature drift of the device within a proper range, and can greatly improve the Q value of the related device and be suitable for silicon-based semiconductor processing technology.

Description

Technical Field

[0001] This invention relates to the field of surface acoustic wave (SAW) filter technology, and in particular to a bottom electrode excited SAW device structure. Background Technology

[0002] Surface acoustic wave (SAW) filters are acoustic devices used in communications, radio, radar, and other related radio frequency front-end applications.

[0003] Currently, relevant SAW devices mainly include various types and structures such as traditional SAW, TC-SAW, and IHP-SAW. TC-SAW is an acoustic device that suppresses temperature drift by coating a SiO2 temperature-compensated film layer onto a basic SAW structure, and is widely used in communication terminals. IHP-SAW, also known as TF-SAW, is a new type of acoustic device that achieves higher performance by optimizing and modifying the piezoelectric substrate through a multilayer film structure. Regardless of the structure, the working principle of SAW devices is basically the same: comb-shaped interdigital transducers are fabricated on the surface of piezoelectric materials or substrates with piezoelectric material layers using semiconductor processing technology. The piezoelectric and inverse piezoelectric effects of the piezoelectric layer enable electro-acoustic-electro-electric signal propagation, thereby achieving the filtering of communication signals. Commonly used piezoelectric materials include lithium tantalate (LiTaO3, LT), lithium niobate (LiNbO3, LN), aluminum nitride (AlN), and zinc oxide (ZnO), with LT and LN being the most common. Piezoelectric materials (LT) and lithium nanotubes (LN) are mostly synthetic materials with high plasticity and strong corrosion resistance, making them difficult to process with precision. For example, when using through-hole technology to create openings in LT and LN, the conventional processing depth can only be maintained between several hundred nanometers and 1 micrometer, making micrometer-level processing difficult. Furthermore, key material parameters such as the coefficient of thermal expansion are incompatible with silicon-based materials. Therefore, piezoelectric materials are difficult to integrate with mainstream silicon-based semiconductor processes, resulting in inherent disadvantages in integration and miniaturization of related devices. In addition, for most SAW devices, the comb structure of their effective functional area is located on the outermost surface of the chip. This makes them susceptible to changes in the external environment in terms of sound wave propagation, and the unprotected comb structure is easily damaged by external debris, affecting the overall performance of the device. Therefore, there are almost no bare-chip solutions available for use in the communications field. This further limits the application of related devices in miniaturization and integration.

[0004] Therefore, those skilled in the art are dedicated to developing a bottom electrode excited surface acoustic wave device structure to reduce the influence of the external environment on the surface acoustic wave device, and to achieve temperature compensation to control the temperature drift of the device within a suitable range. In addition, the related device has a significantly improved Q value and is suitable for silicon-based semiconductor processing technology. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a bottom electrode excited surface acoustic wave device structure, which reduces the influence of the external environment on the surface acoustic wave device, and can also realize temperature compensation to control the temperature drift of the device within a suitable range. In addition, the related device has a significantly improved Q value and is suitable for silicon-based semiconductor processing technology.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a bottom electrode excited surface acoustic wave device structure, comprising a supporting substrate layer, an insulating layer and a piezoelectric material layer;

[0007] An insulating layer is disposed on the supporting substrate layer, the thickness of the insulating layer being less than the thickness of the supporting substrate layer. A piezoelectric material layer is disposed on the insulating layer. Interdigitated transducer structures and input / output electrode structures are spaced apart within the insulating layer. The connection ends of the input / output electrode structures extend beyond the piezoelectric material layer or the supporting substrate layer and form solder balls or solder joints. These solder balls or solder joints are located on the surface of the supporting substrate layer or the surface of the piezoelectric material layer.

[0008] The beneficial effects of this invention are as follows: By placing the interdigital transducer structure and the input / output electrode structure below the piezoelectric material layer, and by encapsulating the comb-shaped transducer structure with the piezoelectric material layer above the device and the insulating layer and supporting substrate layer below, the shortcomings of surface acoustic wave devices being easily affected by the external environment are solved. At the same time, temperature compensation can be achieved to control the temperature drift of the device within a suitable range. The device also meets the requirements for subsequent integration in a bare-chip manner. The related devices are not only compatible with silicon-based processes, which is conducive to subsequent integration, but also further improve the Q value and electromechanical coupling coefficient of the device, which is beneficial to improving the performance of the device.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, a first through hole is provided in the piezoelectric material layer, and the first through hole is filled with a first electroplating material. The two ends of the first electroplating material are respectively connected to the input / output electrode structure and the solder ball or solder joint.

[0011] The advantage of adopting the above-mentioned further solutions is that the electroplating materials in the piezoelectric material layer can be adjusted according to different needs, thereby further improving the compatibility of silicon-based processes.

[0012] Furthermore, a second through hole is provided in the supporting substrate layer, and an insulating isolation layer is provided in the second through hole, which is isolated from the supporting substrate layer. The insulating isolation layer is filled with a second electroplating material, and the two ends of the second electroplating material are respectively connected to the input / output electrode structure and the solder ball or solder joint.

[0013] The advantage of adopting the above-mentioned further solutions is that the electroplating materials in the supporting substrate layer can be adjusted accordingly according to different needs, thereby further improving the compatibility of silicon-based processes.

[0014] Furthermore, the solder ball or solder joint also includes a metallization layer disposed on the surface of the piezoelectric material layer or the surface of the supporting substrate layer, and the solder ball or solder joint with electrode leads is disposed on the metallization layer.

[0015] The advantage of adopting the above-mentioned further solution is that the solder balls or solder joints led out from the metallization layer and electrodes are used to connect to external devices.

[0016] Furthermore, grounding electrodes are provided on both sides of the metallized layer.

[0017] The advantage of adopting the above-mentioned further scheme is that the grounding electrode is used for grounding.

[0018] Furthermore, a functional layer is provided between the supporting substrate layer and the insulating layer.

[0019] The beneficial effect of adopting the above-mentioned further scheme is that it sets up corresponding functional layers according to different functions, thereby further improving the versatility of surface acoustic wave devices.

[0020] Furthermore, the supporting substrate layer is made of one of the following materials, including but not limited to silicon-based materials, SiC materials, and sapphire substrate materials.

[0021] The advantage of adopting the above-mentioned further solutions is that the substrate layer can be made of different materials according to different needs, so as to meet the needs of high-end acoustic devices and high integration.

[0022] Furthermore, the functional layer is made of one or more composite film layers including, but not limited to, AlN, diamond, and hexagonal boron nitride, or a multilayer composite film layer structure matched with Bragg reflector grating high and low sound velocity materials.

[0023] The advantage of adopting the above-mentioned further solutions is that different materials are used to make the functional layers according to different needs, so as to meet the needs of high-end acoustic devices and high integration.

[0024] Furthermore, the piezoelectric material layer is made of one of the following materials, including but not limited to LT and LN piezoelectric materials of various cuts, AlN material, and ZnO material.

[0025] The advantage of adopting the above-mentioned further solutions is that the piezoelectric material layer can be made of different materials according to different needs, so as to meet the needs of high-end acoustic devices and high integration. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a specific embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a specific embodiment two of the present invention;

[0028] Figure 3 This is a top view structural diagram of a specific embodiment of the present invention.

[0029] The attached diagram lists the components represented by each number as follows:

[0030] 10. Supporting substrate layer; 20. Functional layer; 30. Insulating layer; 40. Piezoelectric material layer; 50. Interdigital transducer structure; 51. Input / output electrode structure; 52. Ground electrode; 60. First electroplating material; 61. Insulating isolation layer; 62. Second electroplating material; 70. Metallization layer; 80. Solder joint. Detailed Implementation

[0031] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0032] In the description of this invention, it should be understood that the terms "center," "length," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "inner," "outer," "circumferential," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] like Figure 1 , Figure 2 and Figure 3As shown, a bottom-electrode excited surface acoustic wave (SAW) device structure includes a supporting substrate layer 10, an insulating layer 30, and a piezoelectric material layer 40. The insulating layer 30 is disposed on the supporting substrate layer 10, and the surfaces of the supporting substrate layer 10 and the insulating layer 40 are in close contact. The thickness of the insulating layer 30 is less than the thickness of the supporting substrate layer 10. The piezoelectric material layer 40 is disposed on the insulating layer 30, and the piezoelectric material layer 30 is in close contact with the surface of the insulating layer 30. Interdigitated transducer structures 50 and input / output electrode structures 51 are spaced apart within the insulating layer 30, and the connection ends of the input / output electrode structures 51 extend out of the piezoelectric material layer 40 or the supporting substrate layer 10 to form solder balls or solder joints 80, which are located on the surface of the supporting substrate layer 10 or the surface of the piezoelectric material layer 40.

[0036] In this invention, the interdigital transducer structure 50 and the input / output electrode structure 51 are placed below the piezoelectric material layer 40. The comb-shaped transducer structure is enclosed by the piezoelectric material layer 40 above the device and the insulating layer 30 and supporting substrate layer 10 below. This solves the problem of surface acoustic wave devices being easily affected by the external environment, and also achieves temperature compensation to control the temperature drift of the device within a suitable range. The device also meets the requirements for subsequent integration in a bare-chip manner. In addition, the piezoelectric material layer 40 in this structure is only a few hundred nanometers long. The electrodes of the comb-shaped transducer can be led out through the piezoelectric material or through the SiO2 and supporting substrate layer 10 materials, which can be adjusted according to the requirements, and can achieve silicon-based process compatibility. The related device is not only compatible with silicon-based processes, which is conducive to subsequent integration, but also can further improve the Q value and electromechanical coupling coefficient of the device, which is beneficial to improving the performance of the device. Furthermore, devices using this structure have temperature compensation capabilities, enabling low temperature drift or even zero temperature drift. At the same time, the development of related devices is compatible with silicon-based processes, which is conducive to the integrated development of micro-acoustic devices. The related structure also has certain improvements in Q value and electromechanical coupling coefficient, making it suitable for the research and development of high-end advanced acoustic devices.

[0037] Example 1

[0038] like Figure 1 , Figure 3 As shown, a first through hole is provided in the piezoelectric material layer 40. The first through hole is opened on the piezoelectric material layer 40 by laser. After the first through hole is cleaned, a first electroplating material 60 is filled into the first through hole by electroplating, sputtering, etc., so that the two ends of the first electroplating material 60 are respectively connected to the input / output electrode structure 51 and the solder ball or solder joint 80. The solder ball or solder joint 80 is connected for connection with external devices.

[0039] Example 2

[0040] like Figure 2 , Figure 3As shown, a second through hole is provided in the support substrate layer 10. The second through hole can also be opened by laser. After cleaning, an insulating isolation layer 61 is provided in the second through hole, which is isolated from the support substrate layer 10. The insulating isolation layer 61 can be made by electroplating. The insulating isolation layer 61 is filled with a second electroplating material 62. The two ends of the second electroplating material 62 are respectively connected to the input / output electrode structure 51 and the solder ball or solder joint 80. The solder ball or solder joint 80 is connected for connection with external devices.

[0041] In this embodiment, the supporting substrate layer 10 is made of one of the following materials, including but not limited to silicon-based materials (high-resistivity silicon), SiC materials, and sapphire substrate materials. Alternatively, functional layer materials, such as AlN hypersonic layer, diamond, etc., may be deposited on the above materials according to corresponding requirements.

[0042] In some embodiments, the solder balls or solder joints 80 further include a metallization layer 70 disposed on the surface of the piezoelectric material layer 40 or the surface of the supporting substrate layer 10. The metallization layer 70 is a sub-metallization layer and contains solder pads. Solder balls or solder joints 80 with electrode leads are also disposed on the metallization layer 70. The solder balls or solder joints 80 facilitate connection with external devices. The solder balls or solder joints 80 can be made of materials such as gold or solder. Ground electrodes 52 are also disposed on both side walls of the metallization layer 70. The piezoelectric material layer 40 is made of one of the following materials, including but not limited to LT and LN piezoelectric materials of various cuts, AlN materials, and ZnO materials, or other related piezoelectric materials.

[0043] In another embodiment, a functional layer 20 is provided between the supporting substrate layer 10 and the insulating layer 30. Different functional layers 20 are selected according to the actual application of surface acoustic waves. The functional layer 20 is made of one or more composite film layers including but not limited to AlN, diamond, hexagonal boron nitride, or a multilayer composite film layer structure that is matched with Bragg reflector grating type high and low sound velocity materials.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bottom-electrode-excited surface acoustic wave device structure, characterized in that: It includes a supporting substrate layer (10), an insulating layer (30), and a piezoelectric material layer (40); The insulating layer (30) is disposed on the supporting substrate layer (10), the thickness of the insulating layer (30) is less than the thickness of the supporting substrate layer (10), the piezoelectric material layer (40) is disposed on the insulating layer (30), interdigital transducer structures (50) and input / output electrode structures (51) are disposed at intervals in the insulating layer (30), the interdigital transducer structures (50) and input / output electrode structures (51) are disposed at intervals in the insulating layer (30), the interdigital transducer structures (50) are wrapped from the top and bottom sides by the insulating layer (30) and the piezoelectric material layer (40), and the connection end of the input / output electrode structure (51) extends out of the piezoelectric material layer (40) or the supporting substrate layer (10) and forms a solder ball or solder point (80), the solder ball or solder point (80) is located on the surface of the supporting substrate layer (10) or the surface of the piezoelectric material layer (40).

2. The bottom electrode excited surface acoustic wave device structure according to claim 1, characterized in that: The piezoelectric material layer (40) has a first through hole, which is filled with a first electroplating material (60). The two ends of the first electroplating material (60) are respectively connected to the input / output electrode structure (51) and the solder ball or solder joint (80).

3. The bottom electrode excited surface acoustic wave device structure according to claim 1, characterized in that: The supporting substrate layer (10) is provided with a second through hole, and an insulating isolation layer (61) is provided in the second through hole, which is isolated from the supporting substrate layer (10). The insulating isolation layer (61) is filled with a second electroplating material (62), and the two ends of the second electroplating material (62) are respectively connected to the input / output electrode structure (51) and the solder ball or solder joint (80).

4. The bottom electrode excited surface acoustic wave device structure according to any one of claims 1 to 3, characterized in that: The solder ball or solder joint (80) further includes a metallization layer (70) disposed on the surface of the piezoelectric material layer (40) or the surface of the supporting substrate layer (10), and the solder ball or solder joint (80) with electrode leads is disposed on the metallization layer (70).

5. The bottom electrode excited surface acoustic wave device structure according to claim 4, characterized in that: The metallization layer (70) is also provided with grounding electrodes (52) on both sides of its sidewalls.

6. The bottom electrode excited surface acoustic wave device structure according to claim 4, characterized in that: A functional layer (20) is further provided between the supporting substrate layer (10) and the insulating layer (30).

7. The bottom electrode excited surface acoustic wave device structure according to claim 4, characterized in that: The supporting substrate layer (10) is made of one of the following materials, including but not limited to silicon-based materials, SiC materials, and sapphire substrate materials.

8. The bottom electrode excited surface acoustic wave device structure according to claim 6, characterized in that: The functional layer (20) is made of one or more composite film layers including but not limited to AlN, diamond, and hexagonal boron nitride, or a multilayer composite film layer structure matched with Bragg reflector grating high and low sound velocity materials.

9. The bottom electrode excited surface acoustic wave device structure according to claim 4, characterized in that: The piezoelectric material layer (40) is made of one of the following materials, including but not limited to LT and LN piezoelectric materials of various cuts, AlN material, and ZnO material.

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