Surface acoustic wave filter chip with frequency adjustment structure and preparation method thereof
By designing the interdigit metal region and silica fill layer on the substrate of the surface acoustic wave filter chip, frequency adjustment is performed using magnetron sputtering and chemical mechanical polishing processes, the problems of complex frequency adjustment and low production efficiency in the prior art are solved, and the frequency characteristics and production efficiency are improved.
Patent Information
- Application Number
- CN202510075837.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-06-10
AI Technical Summary
In the existing surface acoustic wave filter manufacturing process, the frequency adjustment technology is complex, the precision equipment is dependent, and the trim operation speed is slow, which can easily lead to excessive temperature, affecting product reliability and production yield.
A surface acoustic filter chip with a frequency adjustment structure is designed, by setting the interdigit metal region and a silica fill layer on the substrate, filling the silica material with magnetron sputtering deposition technology, and frequency adjustment is performed in combination with chemical mechanical polishing process.
This avoids complex trim operations, improves the frequency characteristics of surface acoustic wave filters, ensures the structural stability and production efficiency of the device, reduces production costs, and provides a new technical path for the research and development of high-performance filters.
Smart Images
Figure CN120128126A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical fields of microelectronics and surface acoustic wave (SAW) technology, and particularly relates to a surface acoustic wave filter chip with a frequency adjustment structure and a preparation method thereof. Background Art
[0002] In the existing manufacturing process of surface acoustic wave filters, frequency adjustment is a key link. Traditional methods usually include using SiO 2 for passivation operations to reduce the frequency, or relying on precision trim equipment to thin the metal electrodes to increase the frequency. However, the trim operation is not only technically complex, requires high skills of operators, but also has extremely high dependence on equipment, increasing the production cost and process difficulty. In addition, the trim process rate is slow, and long-term operation is likely to cause local overheating, which may lead to the accumulation of thermal stress in the piezoelectric substrate, and ultimately cause the substrate to fracture, seriously affecting the reliability and production yield of the product. Summary of the Invention
[0003] The present invention provides a surface acoustic wave filter chip with a frequency adjustment structure and a preparation method thereof to solve one or several of the technical problems existing in the prior art.
[0004] The technical solution of the present invention to solve the above technical problems is as follows: A surface acoustic wave filter chip with a frequency adjustment structure includes a substrate, and a finger metal region is provided on one side surface of the substrate, and a silicon dioxide filling layer is provided on the substrate between the finger metal regions.
[0005] The beneficial effect of the present invention is: The purpose of the present invention is to provide a novel frequency increase structure. By cleverly designing the combination mode of the finger metal region and the silicon dioxide material, it not only avoids the complex trim operation, but also effectively improves the frequency characteristics of the surface acoustic wave filter, while ensuring the structural stability and production efficiency of the device, reducing the production cost, and providing a new technical path for the research and development of high-performance filters.
[0006] On the basis of the above technical solution, the present invention can be further improved as follows.
[0007] Further, the finger metal region includes a finger transducer region and a bonding pad electrode region, and the thickness of the silicon dioxide filling layer is not less than the height of the finger transducer region.
[0008] Further, the height of the bonding pad electrode region is greater than the height of the finger transducer region.
[0009] Further, a silicon dioxide protection layer is provided on the finger transducer region, the bonding pad electrode region, and the silicon dioxide filling layer.
[0010] Further, a silicon dioxide protective layer is provided on the interdigital transducer region and the silicon dioxide filling layer.
[0011] Further, the surface of the silicon dioxide protective layer is flush with the surface of the bonding electrode region.
[0012] Further, a layer of titanium-aluminum electrode is provided in the interdigital transducer region, and two layers of titanium-aluminum electrodes are provided in the bonding electrode region.
[0013] Further, in the bonding electrode region, the thickness of the lower titanium-aluminum electrode is the same as that of the titanium-aluminum electrode in the interdigital transducer region, and the thickness of the upper titanium-aluminum electrode is less than that of the lower titanium-aluminum electrode.
[0014] Further, the titanium-aluminum electrode includes a titanium film and an aluminum film, and the titanium film is located below the aluminum film.
[0015] A preparation method of a surface acoustic wave filter chip with a frequency adjustment structure includes the following steps:
[0016] S1, spin-coat a layer of photoresist on one side of the substrate, and then perform a lithography operation for patterning.
[0017] S2, use an electron beam evaporation device to evaporate a layer of titanium-aluminum electrode on one side of the patterned substrate, then remove the photoresist, complete the electrode patterning, and form an interdigital metal region on one side of the substrate.
[0018] S3, spin-coat a layer of photoresist on one side of the substrate again, and then perform a lithography operation to expose the bonding electrode region in the interdigital metal region, and the interdigital transducer region in the interdigital metal region is protected by the photoresist.
[0019] S4, use the electron beam evaporation device to evaporate a layer of titanium-aluminum electrode again to make the bonding electrode region have two layers of titanium-aluminum electrodes, and then remove the photoresist.
[0020] S5, use magnetron sputtering to sputter silicon dioxide on one side of the substrate to fill the substrate between the interdigital metal regions with a silicon dioxide filling layer, and form a layer of silicon dioxide protective layer on the interdigital metal region and the silicon dioxide filling layer.
[0021] S6, use a chemical mechanical polishing process to thin the silicon dioxide protective layer to meet the frequency requirements of the surface acoustic wave filter chip.
[0022] The beneficial effects of the present invention are as follows: The preparation method of the present invention, by ingeniously designing the combination mode of the interdigital metal region and the silica material, not only avoids complex trimming operations, but also effectively improves the frequency characteristics of the surface acoustic wave filter, while ensuring the structural stability and production efficiency of the device, reducing the production cost, and providing a new technical path for the research and development of high-performance filters.
[0023] The preparation method of the present invention also has the following advantages:
[0024] (1) Simplify the process flow: Avoid complex trimming operations, reduce equipment dependence, and lower production costs and cycles.
[0025] (2) Improve the frequency adjustment accuracy: Through material filling and surface treatment, fine control of the frequency is achieved, improving the performance consistency of the product.
[0026] (3) Enhance the structural stability: The filling of silica enhances the structural strength of the chip and reduces the risk of damage caused by external factors.
[0027] (4) Improve production efficiency and yield: Reduce the scrap rate caused by improper trimming operations and improve the overall production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 is the structural schematic diagram of Step 1 of the present invention Figure 1 ;
[0029] Figure 2 is the structural schematic diagram of Step 1 of the present invention Figure 2 ;
[0030] Figure 3 is the structural schematic diagram of Step 2 of the present invention Figure 1 ;
[0031] Figure 4 is the structural schematic diagram of Step 2 of the present invention Figure 2 ;
[0032] Figure 5 is the structural schematic diagram of Step 2 of the present invention Figure 3 ;
[0033] Figure 6 is the structural schematic diagram of Step 2 of the present invention Figure 4 ;
[0034] Figure 7 is Figure 6 the partial enlarged structural schematic diagram in
[0035] Figure 8 is the structural schematic diagram of Step 2 of the present invention Figure 5 ;
[0036] Figure 9 is Figure 8 a schematic diagram of a partially enlarged structure in
[0037] Figure 10 a schematic diagram of the structure of step 3 of the present invention;
[0038] Figure 11 is Figure 10 a schematic diagram of a partially enlarged structure in
[0039] Figure 12 a schematic diagram of the structure of step 4 of the present invention Figure 1 ;
[0040] Figure 13 is Figure 12 a schematic diagram of a partially enlarged structure in
[0041] Figure 14 a schematic diagram of the structure of step 4 of the present invention Figure 2 ;
[0042] Figure 15 is Figure 14 a schematic diagram of a partially enlarged structure in
[0043] In the attached drawings, the list of components represented by each label is as follows:
[0044] 1. Substrate; 2. First photoresist; 3. Second photoresist; 4. Titanium film; 5. Aluminum film; 6. Silicon dioxide. Specific embodiments
[0045] The principles and features of the present invention will be described below with reference to the attached drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.
[0046] As Figures 1 to 15 shown, a surface acoustic wave filter chip with a frequency adjustment structure in this embodiment includes a substrate 1, and a finger metal area is provided on one side surface of the substrate 1, and a silicon dioxide filling layer is provided on the substrate between the finger metal areas.
[0047] As Figure 8 and Figure 9 shown, the finger metal area in this embodiment includes a finger transducer area and a bonding electrode area, and the thickness of the silicon dioxide filling layer is not less than the height of the finger transducer area.
[0048] As Figure 8 and Figure 9 shown, the height of the bonding electrode area in this embodiment is greater than the height of the finger transducer area.
[0049] As Figure 10 and Figure 11As shown, in an alternative solution of this embodiment, a silicon dioxide protective layer is provided on the interdigital transducer region, the bonding pad electrode region, and the silicon dioxide filling layer.
[0050] As Figure 12 and Figure 13 shown, in another alternative solution of this embodiment, a silicon dioxide protective layer is provided on the interdigital transducer region and the silicon dioxide filling layer. Specifically, the surface of the silicon dioxide protective layer is flush with the surface of the bonding pad electrode region.
[0051] As Figure 8 and Figure 9 shown, in this embodiment, a layer of titanium-aluminum electrode is provided in the interdigital transducer region, and two layers of titanium-aluminum electrodes are provided in the bonding pad electrode region.
[0052] As Figure 8 and Figure 9 shown, in the bonding pad electrode region of this embodiment, the thickness of the lower titanium-aluminum electrode is the same as that of the titanium-aluminum electrode in the interdigital transducer region, and the thickness of the upper titanium-aluminum electrode is less than that of the lower titanium-aluminum electrode.
[0053] As Figure 8 and Figure 9 shown, the titanium-aluminum electrode of this embodiment includes a titanium film 4 and an aluminum film 5, and the titanium film 4 is located below the aluminum film 5.
[0054] A surface acoustic wave filter chip with a frequency adjustment structure in this embodiment fills the interdigital metal regions of the surface acoustic wave filter chip with silicon dioxide material by using magnetron sputtering deposition technology. This design not only enhances the structural strength of the chip, reduces the deformation caused by external force or temperature change, but also affects the propagation speed of the surface acoustic wave by changing the medium characteristics on the acoustic wave propagation path, so as to achieve fine adjustment of the frequency. The thin silicon dioxide on the surface of the interdigital metal not only serves as a protective layer to prevent the metal electrode from being corroded or damaged in the subsequent process or use, but more importantly, by precisely controlling the thickness of this thin silicon dioxide layer, the mass loading of the metal interdigital fingers can be further adjusted, so as to adjust the propagation characteristics of the surface acoustic wave and achieve the purpose of precisely adjusting the frequency.
[0055] The purpose of this embodiment is to provide a novel frequency improvement structure. By cleverly designing the combination mode of the interdigital metal region and the silicon dioxide material, it not only avoids complex trim operations, but also effectively improves the frequency characteristics of the surface acoustic wave filter, while ensuring the structural stability and production efficiency of the device, reducing the production cost, and providing a new technical path for the research and development of high-performance filters.
[0056] As Figures 1 to 15As shown in the figure, a preparation method of a surface acoustic wave filter chip with a frequency adjustment structure according to this embodiment includes the following steps:
[0057] S1, spin-coat a layer of photoresist (this photoresist is the first photoresist 2) on one side of the substrate 1, and then perform a lithography operation for patterning.
[0058] S2, use an electron beam evaporation device to evaporate a layer of titanium-aluminum electrode on one side of the patterned substrate 1, and then remove the photoresist to complete the electrode patterning, and form an interdigital metal region on one side of the substrate; the photoresist is removed by the lift-off process.
[0059] S3, spin-coat another layer of photoresist (this photoresist is the second photoresist 3) on one side of the substrate 1, and then perform a lithography operation to expose the bonding electrode region in the interdigital metal region, and the interdigital transducer region in the interdigital metal region is protected by the photoresist.
[0060] S4, use the electron beam evaporation device to evaporate another layer of titanium-aluminum electrode again, so that the bonding electrode region has two layers of titanium-aluminum electrodes, and then remove the photoresist.
[0061] S5, use magnetron sputtering to sputter silicon dioxide 6 on one side of the substrate, so that the substrate between the interdigital metal regions is filled with a silicon dioxide filling layer, and a silicon dioxide protection layer is formed on the interdigital metal region and the silicon dioxide filling layer.
[0062] S6, use chemical mechanical polishing process to thin the silicon dioxide protection layer to meet the frequency requirements of the surface acoustic wave filter chip. Specifically, use a CMP device to thin the silicon dioxide on the surface. The silicon dioxide 6 in the metal interdigital gap changes the propagation mode of the acoustic wave and increases the frequency; the silicon dioxide 6 on the surface of the metal interdigital increases the mass load and reduces the frequency. The final frequency is determined by the competition relationship between the two, and the precise increase of the frequency can be achieved by adjusting the thickness of the polished silicon dioxide 6.
[0063] The preparation method of this embodiment, by cleverly designing the combination mode of the interdigital metal region and the silicon dioxide material, not only avoids complex trim operations, but also effectively improves the frequency characteristics of the surface acoustic wave filter, while ensuring the structural stability and production efficiency of the device, reducing the production cost, and providing a new technical path for the research and development of high-performance filters.
[0064] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "thickness", "height", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.
[0065] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.
[0066] In the present invention, unless otherwise clearly specified and defined, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0067] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.
[0068] In the description of this specification, the descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.
[0069] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.
Claims
1. A surface acoustic wave filter chip with a frequency adjustment structure, characterized in that: The invention comprises a substrate, one side of which is provided with an interdigitated metal region, and a silicon dioxide filling layer is provided on the substrate between the interdigitated metal regions.
2. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 1, characterized in that: The interdigital metal region includes an interdigital transducer region and a pressure welding electrode region, and the thickness of the silicon dioxide filling layer is not less than the height of the interdigital transducer region.
3. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 2, characterized in that: The height of the pressure welding electrode area is greater than the height of the interdigital transducer area.
4. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 2, characterized in that: A silicon dioxide protective layer is provided on the interdigital transducer region, the pressure welding electrode region and the silicon dioxide filling layer.
5. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 2, characterized in that: A silicon dioxide protection layer is provided on the interdigital transducer region and the silicon dioxide filling layer.
6. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 5, characterized in that: The surface of the silicon dioxide protection layer is flush with the surface of the pressure welding electrode region.
7. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 2, characterized in that: The interdigital transducer region is provided with a layer of titanium-aluminum electrodes, and the pressure welding electrode region is provided with two layers of titanium-aluminum electrodes.
8. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 7, characterized in that: In the pressure welding electrode region, the thickness of the titanium aluminum electrode located in the lower layer is the same as the thickness of the titanium aluminum electrode in the interdigital transducer region, and the thickness of the titanium aluminum electrode located in the upper layer is less than the thickness of the titanium aluminum electrode located in the lower layer.
9. The surface acoustic wave filter chip with a frequency adjustment structure according to claim 7, characterized in that: The titanium-aluminum electrode comprises a titanium film and an aluminum film, and the titanium film is located below the aluminum film.
10. A method for preparing a surface acoustic wave filter chip having a frequency adjustment structure according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, spin coating a layer of photoresist on one side of the substrate, and then performing photolithography operation for patterning; S2, using an electron beam evaporation device to evaporate a layer of titanium aluminum electrode on one side of the substrate that has been patterned, and then removing the photoresist to complete the electrode patterning, forming an interdigitated metal area on one side of the substrate; S3, spin-coating a layer of photoresist on one side of the substrate, and then performing a photolithography operation, so that the pressure welding electrode area in the interdigital metal area is exposed, and the interdigital transducer area in the interdigital metal area is protected by the photoresist; S4, using the electron beam evaporation device to evaporate a layer of titanium aluminum electrode again, so that the pressure welding electrode area has two layers of titanium aluminum electrodes, and then removing the photoresist; S5, sputtering silicon dioxide on one side of the substrate by magnetron sputtering, so that the substrate between the interdigitated metal regions is filled with a silicon dioxide filling layer, and a silicon dioxide protective layer is formed on the interdigitated metal regions and the silicon dioxide filling layer; S6, using a chemical mechanical polishing process to thin the silicon dioxide protective layer to meet the frequency requirements of the surface acoustic wave filter chip.