Radio frequency filter comprising a plurality of acoustic wave devices and method of manufacturing thereof

Abstract

The present invention relates to a radio frequency filter including a plurality of acoustic wave devices and a method of manufacturing the same. An embodiment of the radio frequency filter can include a support substrate formed with a plurality of cavities, a piezoelectric plate disposed on the support substrate, a conductive pattern disposed on the piezoelectric plate including at least one interdigital transducer (IDT) electrode, a clear line groove to expose an edge of the support substrate, and at least one first connection hole for communicating the cavities with the clear line groove.

Description

Technical Field

[0001] This invention relates to a filter technology, and more specifically to a radio frequency filter comprising multiple acoustic wave devices and a method for manufacturing the same. Background Technology

[0002] Radio frequency (RF) filters are devices that allow certain frequencies to pass through while blocking others. They are used in wireless communication systems, such as cellular base stations, mobile phones, and computing devices. "Passing through" means transmitting with minimal signal loss, while "blocking" means transmitting with attenuated signals. In RF filters, the frequency range that allows transmission is called the filter's "passband," and the frequency range that blocks transmission is called the filter's "stopband." A typical RF filter has at least one passband and at least one stopband. Specific requirements for the passband or stopband can vary depending on the application. For example, a "passband" can be defined as a small frequency range where the filter's insertion loss is less than a defined value such as 1dB, 2dB, or 3dB. A "stopband" can be defined as a large frequency range where the filter's insertion loss reaches a defined value such as greater than 20dB, 30dB, or 40dB, depending on the application.

[0003] 6G mobile communication, as a next-generation mobile communication technology, is under research and development. 6G mobile communication can support faster terabyte (Tbps) level data transmission speeds by utilizing ultra-high frequency bands and THz frequencies, providing real-time interaction between connected devices by minimizing latency (e.g., 0.1ms). Currently, high-performance radio frequency filters used for communication performance typically utilize surface acoustic wave (SAW) resonators, bulk acoustic wave (BAW) resonators, and film bulk acoustic resonators (FBARs). However, these existing technologies are not suitable for next-generation mobile communications that utilize ultra-high frequency bands and THz frequencies.

[0004] Therefore, there is a need to study radio frequency filters that meet the required characteristics of devices through simple manufacturing processes and are composed of multiple acoustic wave devices with high bandwidth and high frequency suitable for undiminished performance. Summary of the Invention

[0005] Technical issues

[0006] The purpose of this invention is to provide an RF filter that meets the required characteristics of a device through a simple manufacturing process and is composed of multiple acoustic wave devices with high bandwidth and high frequency suitable for undiminished performance.

[0007] Furthermore, the object of the present invention is to provide an radio frequency filter that minimizes damage to the piezoelectric plate and minimizes the distortion of the acoustic waves caused by damage to the piezoelectric plate.

[0008] Furthermore, the object of the present invention is to provide a method for manufacturing the radio frequency filter.

[0009] The purpose of this invention is not limited to the purposes mentioned above, and other purposes not mentioned can be understood by those skilled in the art through the following description.

[0010] Technical solution

[0011] According to an embodiment of the present invention, the present invention provides a radio frequency filter, comprising: a support substrate having a plurality of cavities; a piezoelectric plate disposed on the support substrate; a conductive pattern disposed on the piezoelectric plate, including at least one conductive pattern (IDT) electrode; an exposed groove exposing the edge of the support substrate; and at least one first connection hole for connecting the cavities to the exposed groove.

[0012] In one embodiment, the exposed groove allows a height difference between the piezoelectric plate and the supporting substrate, the height difference being greater than or equal to the sum of the thickness of the piezoelectric plate and the height of the first connecting hole. The exposed groove has a predetermined width and is formed along the edge of the supporting substrate. The direction of the first connecting hole may be perpendicular to the thickness direction of the supporting substrate. The height of the first connecting hole may be less than or equal to the height of the cavity. The height of the first connecting hole may be 0.2 to 1.0 times the height of the exposed groove. The width of the first connecting hole may be 0.1 to 0.9 times the width of the cavity.

[0013] The region of the piezoelectric plate overlapping at least one cavity and the conductive patterned electrode disposed in the region of the piezoelectric plate can be defined as a bulk acoustic wave device, and the radio frequency filter can be composed of multiple bulk acoustic wave devices. If the bulk acoustic wave device includes two cavities disposed apart from each other, it may also include a second connecting hole that connects the two cavities within the bulk acoustic wave device.

[0014] The piezoelectric substrate is made of one of lithium niobate (LiNbO3), lithium tantalate, lanthanum gallium silicate, gallium nitride, aluminum nitride, zinc oxide, or lead zirconate titanate (PZT). The conductive patterned electrode is made of aluminum (Al), copper (Cu), platinum (Pt), gold (Au), silver (Ag), titanium (Ti), nickel (Ni), chromium (Cr), molybdenum (Mo), tungsten (W), or an alloy of these metals. The support substrate may be made of one of silicon (Si), quartz, glass, silicon carbide (SiC), or sapphire.

[0015] The radio frequency filter is one of the following: band-stop filter, band-pass filter, duplexer, or multiplexer.

[0016] According to another embodiment of the present invention, a method for manufacturing an RF filter may include the following steps: preparing a support substrate having at least one cavity and at least one first connection hole; filling the cavity and the first connection hole with a sacrificial material; forming a piezoelectric plate on the support substrate where the cavity and the first connection hole are filled with the sacrificial material; forming a visible groove along the edge of the support substrate to expose the edge of the support substrate; and an etching step for removing the sacrificial material filling the first connection hole and the cavity that communicates with the visible groove, wherein one end of the first connection hole is open through the visible groove. The method for manufacturing an RF filter may further include the following step: forming a conductive pattern in the region of the piezoelectric plate overlapping the cavity.

[0017] The sacrificial material can be a silicon oxide film or a photoresist. The support substrate may further include a second connecting hole for connecting two adjacent cavities. The height of the first connecting hole may be less than or equal to the height of the cavity. The height of the first connecting hole may be 0.2 to 1.0 times the height of the exposed groove. The width of the first connecting hole may be 0.1 to 0.9 times the width of the cavity.

[0018] According to another embodiment of the present invention, the present invention can provide an acoustic wave device, comprising: a support substrate having at least one cavity formed thereon; a piezoelectric plate disposed on the support substrate; at least one conductive patterned electrode disposed on the piezoelectric plate; and at least one first connecting hole for communicating the cavity with the outside, perpendicular to the thickness direction of the piezoelectric plate.

[0019] The effects of the invention

[0020] According to an embodiment of the present invention, a radio frequency filter and a method thereof can be provided that meet the required characteristics of the device through a simple manufacturing process and are composed of a plurality of acoustic wave devices with high bandwidth and high frequency suitable for undiminished performance.

[0021] Furthermore, the RF filter includes: an exposed groove that exposes the edge of the supporting substrate; and at least one first connection hole for connecting the cavity to the exposed groove. This structure minimizes the damage to the piezoelectric plate, thereby minimizing the distortion of the acoustic waves caused by the damage to the piezoelectric plate and satisfying the required characteristics of the resonator.

[0022] However, the effects of the present invention are not limited to those described, and various extensions can be made without departing from the technical concept and field of the present invention. Attached Figure Description

[0023] Figure 1 This is a top view of a radio frequency filter composed of multiple acoustic wave devices according to an embodiment of the present invention.

[0024] Figure 2a and Figure 2b This is a perspective view of a radio frequency filter composed of multiple acoustic wave devices according to an embodiment of the present invention.

[0025] Figures 3a to 3c This is a cross-sectional view of a radio frequency filter composed of multiple acoustic wave devices according to an embodiment of the present invention.

[0026] Figures 4a to 9e The figure illustrates a method for manufacturing a radio frequency filter composed of multiple acoustic wave devices according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] BF1 to BE4: Acoustic Wave Devices

[0029] IDT: Conductive Pattern

[0030] 10: Support substrate

[0031] 20: Piezoelectric plate

[0032] 41, 42, 43, 44: From the first open trench to the fourth open trench

[0033] 50: First connecting hole

[0034] 51: Second connecting hole

[0035] C: Cavity Detailed Implementation

[0036] Hereinafter, several embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0037] The following description of several embodiments of the present invention is intended to more clearly illustrate the present invention to those skilled in the art. The scope of the present invention is not limited to the following examples, and the following embodiments can be modified into various implementations.

[0038] The terminology used in this specification is for describing specific embodiments and is not intended to limit the invention. Unless otherwise expressly indicated in the context, singular terms used herein may include plural terms. Furthermore, the terms "comprise" and / or "comprising" as used herein are used to specify the presence of shapes, steps, numbers, actions, components, elements, and / or combinations thereof, and do not preclude the presence or addition of more than one other shape, step, number, action, component, element, and / or combination thereof. Moreover, the term "connected" as used herein may mean not only direct connections between components but also indirect connections between multiple components by providing other components.

[0039] Furthermore, in this specification, when a component is described as being "above" other components, it includes not only cases where the component is in contact with other components, but also cases where other components exist between the two components. The term "and / or" as used in this specification includes one or more of the listed items and all combinations thereof. Moreover, the degree terms "about," "actual," etc., used in this specification are used to mean a range or approximate range of their numerical or degree values, taking into account inherent manufacturing and material tolerances, and are used to prevent unauthorized use of disclosed content relating to precise or absolute numerical values ​​provided to aid in understanding this invention.

[0040] Hereinafter, several embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions or thicknesses of the areas or portions shown in the drawings may be slightly exaggerated for clarity and ease of explanation. Throughout the detailed description, the same reference numerals denote the same structural elements.

[0041] Recently, research and development have been undertaken on laterally excited bulk wave resonators (XBARs) suitable for high-frequency bands and high frequencies. These XBARs comprise conductive patterns (Inter-Digital Transducers: IDTs) formed on thin floating layers or diaphragms of piezoelectric material. Microwave signals applied to the conductive patterns induce shear fundamental acoustic waves within the piezoelectric diaphragm, causing acoustic energy to travel in a direction orthogonal to or through the electric field generated by the conductive patterns—that is, in a direction practically perpendicular to the surface of the layer. Furthermore, compared to conventional resonators, these XBARs offer significantly higher electromechanical coupling and higher high-frequency energy.

[0042] The resonant frequency of this transverse exciter acoustic resonator can be determined based on the thickness of the piezoelectric diaphragm overlapping the cavity. One side of the piezoelectric diaphragm can be exposed or shielded by the cavity. Specifically, if one side of the piezoelectric diaphragm is exposed by the cavity, an open cavity is formed on the other side of the support substrate after the piezoelectric layer is formed on one side of the support substrate by an etching process, or an open cavity is first formed on one side of the support substrate by an etching process, and then the piezoelectric layer is bonded to the base substrate on which the open cavity is formed. If one side of the piezoelectric diaphragm is shielded by the cavity, an etch hole is formed overlapping a portion of the cavity after the piezoelectric layer is formed on one side of the support substrate that is filled with a sacrificial layer within the cavity. The sacrificial layer within the cavity can be removed through the etch hole to form a closed cavity between the support substrate and the piezoelectric layer.

[0043] However, since the etched holes penetrate the piezoelectric layer overlapping the cavity, the piezoelectric diaphragm that causes the shearing of the fundamental acoustic wave can be damaged. Due to the damage to the piezoelectric diaphragm, the resulting fundamental acoustic wave may be distorted, making it difficult to meet the required characteristics of the resonator. Furthermore, the need for a separate space on the upper surface to form the etched holes can increase the size of the device.

[0044] Figure 1 This is a top view of a radio frequency filter 100 composed of multiple acoustic wave devices according to an embodiment of the present invention. Figure 2a and Figure 2b This is a perspective view of a radio frequency filter 100 composed of multiple acoustic wave devices according to an embodiment of the present invention. Figures 3a to 3c This is a cross-sectional view of a radio frequency filter 100 composed of multiple acoustic wave devices according to an embodiment of the present invention.

[0045] Reference Figure 1 , Figure 2a and Figure 2bThe radio frequency filter 100 may include: a support substrate 10 having a plurality of cavities C; a piezoelectric plate 20 disposed on the support substrate 10; a conductive pattern 30 disposed on the piezoelectric plate 20, including at least one conductive pattern electrode; exposed grooves 41, 42, 43, and 44 exposing the edges of the support substrate 10; and at least one first connection hole 50 for connecting the cavities C to the exposed grooves. The exposed grooves may include a first exposed groove 41, a second exposed groove 42, a third exposed groove 43, and a fourth exposed groove 44.

[0046] In one embodiment, the support substrate 10 is a substrate for supporting the piezoelectric plate 20, and may include: a plurality of cavities C forming a space by being adjacent to or in contact with one side of the piezoelectric plate 20; and a plurality of first connecting holes 50 for connecting the cavities C to the exposed wire trench. Non-limitingly, the support substrate 110 may be made of silicon (Si), quartz, glass, silicon carbide (SiC), sapphire, aluminum nitride (AlN), or other materials. For example, the support substrate 10 may include a silicon oxide layer or a crystalline silicon layer. Figure 1 , Figure 2a and Figure 2b Although five cavities C and five first connecting holes 50 are illustrated in the diagram, the invention is not limited thereto, and the support substrate 10 may include five or fewer cavities C and more than five first connecting holes 50. In addition, the support substrate 10 may also include a second connecting hole (not shown) for connecting two cavities.

[0047] In one embodiment, the piezoelectric plate 20 may be made of lithium niobate (LiNbO3). However, the material of the piezoelectric plate 20 is not limited to the above; for example, lithium tantalate, lanthanum gallium silicate, gallium nitride, aluminum nitride, zinc oxide, or lead zirconate titanate (PZT) may also be used. The thickness of the piezoelectric plate 20 formed on one side of the support substrate 10 can be in the range of 10 nm to 500 nm. If the thickness of the piezoelectric plate 20 is less than 10 nm, it is difficult to handle in the manufacturing process and may be easily damaged. If the thickness of the piezoelectric plate 20 is greater than 500 nm, it may be difficult to realize an RF filter that operates at high frequencies and in high-frequency bands. The coefficient of thermal expansion of the support substrate 10 is less than that of the piezoelectric plate 20. By attaching a support substrate 10 with a coefficient of thermal expansion smaller than that of the piezoelectric plate 20 to the piezoelectric plate 20, the size change of the piezoelectric plate 20 can be suppressed when the temperature changes, thereby suppressing changes in the frequency characteristics of the radio frequency filter 100. Furthermore, preferably, the piezoelectric plate 20 can be a single-crystal layer.

[0048] In one embodiment, the conductive pattern 30 may be composed of a plurality of conductive pattern electrodes. Although in Figure 1 , Figure 2a and Figure 2b The example uses five conductive patterned electrodes, but the conductive pattern 30 may include five or fewer conductive patterned electrodes.

[0049] Multiple conductive patterned electrodes extend intersectingly in a direction orthogonal to the electric field direction (X-axis direction). A comb-like pattern can be formed by connecting one end of each conductive patterned electrode to a busbar electrode. Non-limitingly, the conductive patterned electrodes can be aluminum (Al), copper (Cu), platinum (Pt), gold (Au), silver (Ag), titanium (Ti), nickel (Ni), chromium (Cr), molybdenum (Mo), tungsten (W), or an alloy of these metals as the main body. Opposing bias electrodes (not shown) may also be included in a direction orthogonal to the other end of the conductive patterned electrodes. They can be arranged to face each other by connecting the conductive patterned electrodes to an upper busbar electrode and connecting the bias electrodes (not shown) to a lower upper busbar electrode. The length of the bias electrodes may be less than the length of the conductive patterned electrodes. Different electric field velocities can be formed in the intersection regions between the conductive patterned electrodes, the intersection regions between the bias electrodes, and the thickness-related regions of the busbar electrode. The thickness of the conductive patterned electrode can vary depending on the type of metal, and the width of the conductive patterned electrode can be determined based on the required filter performance.

[0050] In one embodiment, visible grooves 41, 42, 43, and 44 are formed with a predetermined width L1 along the edge of the support substrate 10. Non-limitingly, if the support substrate 10 is quadrilateral, it may include four visible grooves 41, 42, 43, and 44. Visible groove 41 may be formed along the right edge of the support substrate 10, visible groove 43 may be formed along the left edge of the support substrate 10, visible groove 42 may be formed along the lower edge of the support substrate 10, and visible groove 44 may be formed along the upper edge of the support substrate 10. The ends of visible grooves 41, 42, 43, and 44 may be connected to each other or not connected to each other. Only one of visible grooves 41, 42, 43, and 44 may be provided depending on the arrangement of the cavity C or the conductive pattern electrode.

[0051] The exposed groove creates a height difference ST between the piezoelectric plate 20 and the support substrate 10. This height difference ST can be greater than or equal to the sum of the thickness of the piezoelectric plate 20 and the height h1 of the first connecting hole. In the etching process described later, the height difference ST can be made greater than the sum of the thickness of the piezoelectric plate 20 and the height h1 of the first connecting hole by etching a portion of the support substrate 10.

[0052] Non-limitingly, the first connecting hole 50 for connecting the relevant cavity C to the exposed grooves 41, 42, 43, 44 can vary depending on the number and arrangement of the exposed grooves 41, 42, 43, 44 and the arrangement of the cavity C or conductive patterned electrodes. For example, the first connecting hole 50 can be connected to one of the exposed grooves 41, 42, 43, 44. The first connecting hole 50 can be formed along a direction perpendicular to the thickness direction of the support substrate 10, and the height h1 of the first connecting hole 50 can be less than or equal to the height h2 of the cavity. Furthermore, the height h1 of the first connecting hole 50 can be 0.2 to 1.0 times the height of the exposed groove h3. The height h3 of the exposed groove h3 can be the same as the height difference ST. If the height h1 of the first connecting hole 50 is less than 0.2 times the height of the open-line groove h3, it will be difficult to remove the sacrificial material filled in the cavity C using etching gas or etching solution. If the height h1 of the first connecting hole 50 is more than 1.0 times the height of the open-line groove h3, the process cost may increase due to the need for additional processes. Furthermore, the width L2 of the first connecting hole 50 can be 0.1 to 0.9 times the width L3 of the cavity C. If the width L2 of the first connecting hole 50 is less than 0.1 times the width L3 of the cavity C, it will be difficult to remove the sacrificial material in the cavity C using etching gas or etching solution. If the width L2 of the first connecting hole 50 is more than 0.9 times the width L2 of the cavity C, the asymmetry of the left and right sides of the cavity C will increase, which may lead to a decrease in filter performance and a deterioration in structural stability, potentially requiring a filling process in the future.

[0053] In one embodiment, the region of the piezoelectric plate 20 overlapping with at least one cavity C and the conductive patterned electrodes disposed in the region of the piezoelectric plate 20 can be defined as a bulk acoustic wave device. For example, refer to Figure 3a A bulk acoustic wave device BF1 can be constructed by forming a base substrate 10 with a cavity C, a piezoelectric plate 10 overlapping with the cavity C, and a conductive patterned electrode disposed in the region of the piezoelectric plate 10. (Refer to...) Figure 3b A bulk acoustic wave device BF3 can be constructed by forming a base substrate 10 with two cavities C, a piezoelectric plate 10 overlapping with the two cavities C, and two conductive patterned electrodes disposed in the piezoelectric plate 10. (Refer to...) Figure 3c A bulk acoustic wave device BF4 can be constructed by forming a base substrate 10 with a cavity C, a piezoelectric plate 10 overlapping with the cavity C, and a conductive patterned electrode disposed in the piezoelectric plate 10. Figure 1 , Figure 2aIn this embodiment, the radio frequency filter 100 may be composed of four bulk acoustic wave devices BF1, BF2, BF3, and BF4. However, the present invention is not limited thereto, and the radio frequency filter 100 may be composed of four or fewer bulk acoustic wave devices or more than four bulk acoustic wave devices.

[0054] On the other hand, such as Figure 3b As shown, if the bulk acoustic wave device BF3 includes two cavities C spaced apart from each other, it may also include a second connecting hole 51 that connects the two cavities C within the bulk acoustic wave device BF3. During the etching process described later, the sacrificial material of the cavities C within the bulk acoustic wave device BF3 can be removed symmetrically and stably through the first connecting hole 50 and the second connecting hole 51. The second connecting hole 51 can be exposed to the outside through the etching hole H.

[0055] In this invention, the radio frequency filter 100 can be one of a band-stop filter, a band-pass filter, a duplexer, or a multiplexer.

[0056] Observing the operation of the acoustic wave devices BF1, BF2, BF3, and BF4 of the present invention, if a radio frequency signal is applied to the conductive patterned electrodes, the radio frequency signal can generate a time-varying electric field between the conductive patterned electrodes. In this case, the direction of the electric field can be the x-direction or a direction parallel to the surface of the piezoelectric substrate 120. Due to the high dielectric constant of the piezoelectric plate 20, the electric field is more concentrated within the piezoelectric plate 20 than in air. The electric field in the x-direction can induce shear deformation. Therefore, a fundamental shear acoustic wave mode can be strongly induced within the piezoelectric plate 20. In the present invention, "shear deformation" is defined as the deformation in which mutually parallel surfaces within a material remain parallel and maintain a predetermined distance during deformation. "Shear acoustic wave mode" is defined as the acoustic wave vibration mode of the medium that causes shear deformation of the medium. The atomic motion based on the shear deformation of the acoustic wave devices BF1, BF2, BF3, and BF4 is mostly along the x-direction, but the direction of acoustic energy flow of the excited fundamental shear acoustic wave mode can be the thickness direction of the piezoelectric plate 20.

[0057] As described above, since the sacrificial material inside the cavity is removed through the first connection hole 50 of the present invention, there is no need to use an etched hole that penetrates the piezoelectric plate. This is different from the past. Because no etched hole is used, the damage to the piezoelectric plate can be minimized. Furthermore, the distortion of the acoustic waves caused by the damage to the piezoelectric plate can be minimized, thus satisfying the required characteristics of the resonator.

[0058] Although the present invention uses an etched hole H communicating with the second connecting hole 51, the etched hole H is located in a region that does not overlap with the cavity, i.e., it is located between the cavities, and will not cause distortion of the acoustic waves caused by the piezoelectric diaphragm. That is, the etched hole H has almost no effect on the acoustic waves caused by the piezoelectric diaphragm. However, conventional etched holes that overlap with the cavity and penetrate the piezoelectric diaphragm can cause acoustic wave distortion due to their influence on the acoustic waves caused by the piezoelectric diaphragm.

[0059] Figures 4a to 9e The figure illustrates a method for manufacturing a radio frequency filter composed of multiple acoustic wave devices according to an embodiment of the present invention.

[0060] Reference Figures 4a to 9e The present invention provides a method for manufacturing an radio frequency filter, comprising the following steps: preparing a support substrate having at least one cavity C and at least one horizontal connecting hole 50, 51. Figures 4a to 4e ); fill cavity C and horizontal connecting holes 50 and 51 with sacrificial material SM. Figures 5a to 5e A piezoelectric plate 20 is formed on the support substrate 10, which is filled with sacrificial material SM, in the cavity C and the horizontal connecting holes 50 and 51. Figures 6a to 6e ); A visible groove is formed along the edge of the support substrate 10 to expose the edge of the support substrate 10. Figures 8a to 8e ); and an etching step to remove the sacrificial material SM filling the horizontal connecting holes 50, 51 and cavity C that communicate with the open-line trench ( Figures 9a to 9e It may also include the step of forming a conductive pattern (multiple conductive patterns) in the region of the piezoelectric plate 20 overlapping with the cavity C. Figures 7a to 7e The steps for forming conductive patterns (multiple conductive patterns) Figures 7a to 7e In the step of forming the piezoelectric plate 20 ( Figures 6a to 6e This can be performed after the step of forming the open trench ( ). Figures 8a to 8e ) or etching step ( Figures 9a to 9e Then execute.

[0061] Figure 4a A top view of a support substrate 10 having at least one cavity C and at least one horizontal connecting hole 50, 51. Figure 4b A perspective view of the supporting substrate 10. Figures 4c to 4e This is a cross-sectional view of the supporting substrate 10. Figure 4c This is a sectional view of line A-A'. Figure 4d This is a sectional view of line B-B'. Figure 4eThis is a cross-sectional view along line C-C'. The purpose of the first connecting hole 50 is to remove the sacrificial material SM filling the cavity C during the etching process by communicating with the cavity C and the open line groove described later. The purpose of the second connecting hole 51 is to remove the sacrificial material SM filling the cavity C together with the horizontal connecting hole 50 during the etching process by connecting the two cavities C.

[0062] exist Figure 4a and Figure 4b In this example, there are 5 cavities C, 5 first connecting holes 50, and 1 second connecting hole 510. This is an example provided, but the invention is not limited to this. When designing an RF filter, the number and arrangement of cavities C, first connecting holes 50, and second connecting holes 510 can be determined in various ways. Furthermore, in... Figure 4a and Figure 4b Although cavity C is rectangular, its shape can be various polygonal, circular, conical, trapezoidal, or other forms. Furthermore, the width and height of the first connecting hole 50 can be determined based on the distance between cavity C and the openwork groove described later, and can be designed in various ways depending on the arrangement of cavity C. Similarly, the width and height of the second connecting hole 51 can be determined based on the distance between the cavities C to be connected, and therefore can be designed in various shapes depending on the arrangement of cavity C.

[0063] Figure 5a A top view of the support substrate 10, in which the cavity C and horizontal connecting holes 50 and 51 are filled with sacrificial material SM. Figure 5b for Figure 5a A perspective view of the support substrate 10. Figures 5c to 5e for Figure 5a A cross-sectional view of the support substrate 10. Figure 5c This is a sectional view of line A-A'. Figure 5d This is a sectional view of line B-B'. Figure 5e This is a cross-sectional view along line C-C'. Non-limitingly, the sacrificial material SM may include a silicon oxide film or a photoresist. The sacrificial material SM may be a nitride film (Si3N4) or polycrystalline silicon. The photoresist may include one of krypton fluoride (KrF), argon fluoride (ArF), or extreme ultraviolet (EUV) photoresist.

[0064] Selectively, the sacrificial material SM is vapor-deposited or coated onto the support substrate 10, which is filled with the cavity C and the horizontal connecting holes 50, 51, at a thickness of less than tens of nm. A thin coating of the sacrificial material SM is applied to one side of the support substrate 10, which is filled with the cavity C and has the horizontal connecting holes 50, 51, thereby improving the planarization of the support substrate 10. When the piezoelectric plate 20 (described later) is vapor-deposited onto one side of the planarized support substrate 10, the piezoelectric plate 20 does not protrude and forms a uniform thickness.

[0065] Figure 6a In order to be in Figure 5a A top view of the intermediate structure of the piezoelectric plate 20 deposited or bonded on the support substrate 10. Figure 6b for Figure 6a A three-dimensional diagram of the intermediate structure. Figures 6c to 6e for Figure 6a A cross-sectional view of the intermediate structure. Figure 6c This is a cross-sectional view of line A-A'. Figure 6d This is a sectional view of line B-B'. Figure 6e This is a cross-sectional view of line C-C'.

[0066] The piezoelectric plate 20 can be deposited or coated onto the support substrate 10. Alternatively, the support substrate 10 and the piezoelectric plate 20 can be bonded together using inorganic or organic materials. The piezoelectric plate 20 can be made of lithium niobate (LiNbO3), lithium tantalate, lanthanum gallium silicate, gallium nitride, aluminum nitride, zinc oxide, or lead zirconate titanate (PZT), etc. Preferably, the piezoelectric plate 20 can be made of lithium niobate (LiNbO3). The thickness of the piezoelectric plate 20 bonded to one side of the support substrate 10 is in the range of 10 nm to 500 nm. If the thickness of the piezoelectric plate 20 is less than 10 nm, it is difficult to process during the manufacturing process and may be easily damaged. If the thickness of the piezoelectric plate 20 is greater than 500 nm, it may be difficult to realize an RF filter that operates at the required high frequency and high frequency band.

[0067] Figure 7a In order to be in Figure 6a A top view of an RF filter 100 in which conductive patterns (multiple conductive pattern electrodes) are formed on the intermediate structure. Figure 7b for Figure 7a A 3D view of the RF filter 100. Figures 7c to 7e for Figure 7a A cross-sectional view of the radio frequency filter 100. Figure 7c This is a sectional view of line A-A'. Figure 7d This is a sectional view of line B-B'. Figure 7e This is a cross-sectional view of line C-C'.

[0068] In this invention, the conductive pattern is defined by a plurality of conductive pattern electrodes formed on the piezoelectric plate 20, and the five conductive pattern electrodes can be arranged in a manner that overlaps with the cavity C respectively. Although in Figure 7a and Figure 7bThe example described uses five conductive patterned electrodes, but the invention is not limited to this. When designing an RF filter, the number and arrangement of conductive patterned electrodes can be determined in various ways to overlap with the cavity C.

[0069] Figure 8a This is a top view of an RF filter 100 with visible grooves formed along its edges. Figure 8b for Figure 8a A 3D view of the RF filter 100. Figures 8c to 8e for Figure 8a A cross-sectional view of the radio frequency filter 100. Figure 8c This is a sectional view of line A-A'. Figure 8d This is a sectional view of line B-B'. Figure 8e This is a cross-sectional view of line C-C'.

[0070] The open trench can be along Figure 6a or Figure 7a The support substrate 10 is formed at its edge. The exposed wire groove can be formed by grooving along the edge of the piezoelectric plate 20 to create a groove of a specified width L1. Alternatively, non-limitingly, the exposed wire groove can be formed during a cutting process. The exposed wire groove can be composed of a first groove 41 on the left, a second groove 42 on the lower side, a third groove 43 on the right side, and a fourth groove 43 on the upper side. The ends of the grooves 41, 42, 43, and 44 may be connected to each other or not. The exposed wire groove can be composed of only one of the grooves 41, 42, 43, and 44, depending on the arrangement of the cavity C or the conductive pattern electrode.

[0071] Furthermore, referring to Figure 8a and Figure 8d An etched hole H can be formed between the second connecting hole 51 that connects the two cavities C. Although in Figure 8a and Figure 8b The example given is a case where there is only one etched hole H, but the invention is not limited thereto. When designing an RF filter, the number and arrangement of etched holes H can be determined in various ways according to the structure of the acoustic device BF. The difference from the past is that the etched hole H does not overlap with the cavity C, and can be formed in the area overlapping with the second connecting hole 51.

[0072] The etched hole H can penetrate the piezoelectric plate 20 at least along its thickness direction, exposing at least a portion of the second connection hole 51 to the outside. Etching gas or etching solution is delivered to the exposed area to remove the sacrificial material SM from the second connection hole 51 and the two cavities C connected to it. In a specific example, the etched hole H penetrates not only the piezoelectric plate 20 along its thickness direction but also at least a portion of the second connection hole 51.

[0073] Furthermore, one end of the first connecting hole 50 can be opened through a visible groove. Specifically, the first connecting hole 50 allows the cross-sectional area of ​​its terminal portion perpendicular to the horizontal direction to be exposed to the outside. Subsequently, etching gas or etching solution is injected through the vertical cross-sectional area of ​​the first connecting hole 50 exposed to the outside, as described later, to remove the sacrificial material SM from the first connecting hole 50 and the cavity C connected to the first connecting hole 50.

[0074] Furthermore, the exposed groove creates a height difference ST between the piezoelectric plate 20 and the support substrate 10. This height difference ST can be greater than or equal to the sum of the thickness of the piezoelectric plate 20 and the height of the first connecting hole h1. The height h1 of the first connecting hole 50 can be less than or equal to the height h2 of the cavity. The height h1 of the first connecting hole 50 can be 0.2 to 1.0 times the height of the exposed groove h3. If the height h1 of the first connecting hole 50 is less than 0.2 times the height of the exposed groove h3, it is difficult to remove the sacrificial material of the cavity C using etching gas or etching solution. If the height h1 of the first connecting hole 50 is more than 1.0 times the height of the exposed groove h3, additional processes are required, potentially increasing process costs. Furthermore, the width L2 of the first connecting hole 50 can be 0.1 to 0.9 times the width L2 of the cavity C. If the width L2 of the first connection hole 50 is less than 0.1 times the width L2 of the cavity C, it will be difficult to remove the sacrificial material of the cavity C by etching gas or etching solution. If the width L2 of the first connection hole 50 is more than 0.9 times the width L2 of the cavity C, the asymmetry of the left and right sides of the cavity C will increase, the performance of the filter will decrease and the stability of the structure will deteriorate, and an additional process of filling the hole may be required.

[0075] Figure 9a A top view of an RF filter 100 with visible grooves formed along its edges. Figure 9b for Figure 9a A 3D view of the RF filter 100. Figures 9c to 9e for Figure 9a A cross-sectional view of the radio frequency filter 100. Figure 9c This is a sectional view of line A-A'. Figure 9d This is a sectional view of line B-B'. Figure 9e This is a cross-sectional view of line C-C'.

[0076] The first connecting hole 50 is exposed to the outside through a visible groove, and the second connecting hole 51 is exposed to the outside through an etching hole H. Etching gas or etching solution is supplied through the exposed first and second connecting holes 50 and 51, thereby removing not only the first and second connecting holes 50 and 51, but also the sacrificial material SM filling the cavity C connected to the first and second connecting holes 50 and 51. The etching gas or etching solution may include hydrofluoric acid (HF), ammonium fluoride (NH4F), acetic acid (CH3COOH), phosphoric acid (H3PO4), acetic acid (CH2H3O2), nitric acid (HNO3), chlorine (CI2), carbon difluoride (CF2), carbon tetrafluoride (CF4), sulfur hexafluoride (SF6), hydrogen bromide (HBr), trifluoromethane (CHF3), argon (Ar), hydrogen (H2), or a combination thereof.

[0077] While preferred embodiments of the invention have been disclosed and specific terminology used in this specification, their purpose is generally to facilitate the explanation of the technical content of the invention and to aid in understanding the invention, and does not limit the scope of the invention. Other modifications based on the technical concept of the invention can be implemented in addition to the embodiments disclosed herein, which will be readily apparent to those skilled in the art. Anyone skilled in the art will understand that referring to… Figures 1 to 8e The radio frequency (RF) filters and their manufacturing methods described in the various embodiments are subject to numerous substitutions, modifications, and variations without departing from the inventive concept. Therefore, the scope of the invention should be determined based on the inventive concept described in the claims, rather than on the described embodiments.

Claims

1. A radio frequency filter, characterized in that, include: The supporting substrate has multiple cavities. A piezoelectric plate is disposed on the supporting substrate; A conductive pattern is disposed on the piezoelectric plate, including at least one conductive pattern electrode; The exposed grooves allow the edges of the support substrate to be visible. as well as At least one first connecting hole is provided for connecting the cavity to the exposed groove.

2. The radio frequency filter according to claim 1, characterized in that, The exposed groove creates a height difference between the piezoelectric plate and the supporting substrate. The height difference is greater than or equal to the sum of the thickness of the piezoelectric plate and the height of the first connecting hole.

3. The radio frequency filter according to claim 1, characterized in that, The exposed groove is formed with a specified width along the edge of the supporting substrate.

4. The radio frequency filter according to claim 1, characterized in that, The direction of the first connecting hole is perpendicular to the thickness direction of the supporting substrate.

5. The radio frequency filter according to claim 1, characterized in that, The height of the first connecting hole is less than or equal to the height of the cavity.

6. The radio frequency filter according to claim 1, characterized in that, The height of the first connecting hole is 0.2 to 1.0 times the height of the exposed groove.

7. The radio frequency filter according to claim 1, characterized in that, The width of the first connecting hole is 0.1 to 0.9 times the width of the cavity.

8. The radio frequency filter according to claim 1, characterized in that, The region of the piezoelectric plate overlapping at least one cavity and the conductive patterned electrodes disposed in the region of the piezoelectric plate are defined as a bulk acoustic wave device. The radio frequency filter is composed of multiple bulk acoustic wave devices.

9. The radio frequency filter according to claim 8, characterized in that, If the bulk acoustic wave device includes two cavities that are spaced apart from each other, it also includes a second connecting hole that connects the two cavities within the bulk acoustic wave device.

10. The radio frequency filter according to claim 1, characterized in that, The piezoelectric substrate is composed of one of lithium niobate, lithium tantalate, lanthanum gallium silicate, gallium nitride or aluminum nitride, zinc oxide or lead zirconate titanate. The conductive patterned electrode is made of aluminum (Al), copper (Cu), platinum (Pt), gold (Au), silver (Ag), titanium (Ti), nickel (Ni), chromium (Cr), molybdenum (Mo), tungsten (W), or an alloy of these metals as the main component. The supporting substrate is made of one of silicon, quartz, glass, silicon carbide, or sapphire.

11. The radio frequency filter according to claim 1, characterized in that, The radio frequency filter is one of the following: band-stop filter, band-pass filter, duplexer, or multiplexer.

12. A method for manufacturing a radio frequency filter, characterized in that, Includes the following steps: A support substrate with at least one cavity and at least one first connection hole is prepared. The cavity and the first connecting hole are filled with sacrificial material; A piezoelectric plate is formed on the support substrate filled with sacrificial material in the cavity and the first connection hole; A visible groove is formed along the edge of the support substrate to expose the edge of the support substrate; and An etching step that removes the sacrificial material filling the first connecting hole and the cavity that communicate with the open line trench. One end of the first connecting hole is open through the exposed groove.

13. The method for manufacturing an RF filter according to claim 12, characterized in that, It also includes the step of forming a conductive pattern in the region of the piezoelectric plate that overlaps with the cavity.

14. The method for manufacturing an RF filter according to claim 12, characterized in that, The sacrificial material is a silicon oxide film or a photoresist.

15. The method for manufacturing an RF filter according to claim 12, characterized in that, The support substrate also includes a second connecting hole for connecting two adjacent cavities.

16. The method for manufacturing an RF filter according to claim 12, characterized in that, The height of the first connecting hole is less than or equal to the height of the cavity.

17. The method for manufacturing an RF filter according to claim 12, characterized in that, The height of the first connecting hole is 0.2 to 1.0 times the height of the exposed groove.

18. The method for manufacturing an RF filter according to claim 12, characterized in that, The width of the first connecting hole is 0.1 to 0.9 times the width of the cavity.

19. An acoustic wave device, characterized in that, include: A supporting substrate having at least one cavity; A piezoelectric plate is disposed on the supporting substrate; At least one conductive patterned electrode is disposed on the piezoelectric plate; as well as At least one first connection hole is provided for communicating the cavity with the outside, and is perpendicular to the thickness direction of the piezoelectric plate.

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