Filter, radio frequency chip and electronic equipment

Abstract

The invention provides a filter, a radio frequency chip and electronic equipment, an interdigital electrode of the filter comprises a first bus bar and a second bus bar which are parallel to each other, release holes are arranged in a specific area between the first bus bar and the second bus bar, and the release holes penetrate through a piezoelectric layer and are communicated with an air cavity. The size of the release hole is smaller than the length of the aperture of the interdigital electrode; after the substrate is etched by injecting an etching material into the release holes of the specific regions, the substrate below the interdigital electrode region can be effectively released, the volume of an air cavity formed after etching is reduced, the substrate below the non-interdigital electrode region is prevented from being released, the mechanical strength and the power tolerance of the filter are improved, and the service life of the filter is prolonged. The filter size is reduced and the subsequent processing difficulty is reduced.

Description

Technical Field

[0001] This application relates to the field of terminal device hardware, and specifically, to a filter, a radio frequency chip, and an electronic device. Background Art

[0002] An acoustic filter is an important component of a mobile communication device and also has important applications in fields such as sensing and detection. In the context of using higher-frequency carrier frequencies in communication technologies to achieve large bandwidth and low-latency communication, the industry urgently needs surface acoustic wave filters with higher frequencies and higher quality factors.

[0003] During the manufacturing process of a cavity-etching type surface acoustic wave filter, release holes need to be etched on the upper surface of the device, and then etching material is injected through the release holes to locally etch the substrate, making the interdigital electrode region suspended. Currently, the release holes are often placed in the region between the finger tips of the interdigital electrode and the bus bar. However, the release holes placed in this way will also etch the substrate in the non-interdigital electrode region during etching, resulting in an overly large air cavity formed after release and reducing the mechanical strength of the device. Therefore, a filter with a small release cavity and high mechanical strength is needed. Summary of the Invention

[0004] This application provides a filter. The release holes of the filter are arranged in a partial area between the bus bars of the interdigital electrodes. After etching the substrate by injecting etching material into the release holes, the volume of the air cavity formed after etching can be effectively reduced.

[0005] In a first aspect, a filter is provided, including: a substrate having an air cavity; a piezoelectric layer located above the substrate; an interdigital electrode located above the piezoelectric layer, the interdigital electrode including a first bus bar and a second bus bar that are parallel to each other, and the interdigital electrode further including fingers extending along a first direction from the first bus bar and the second bus bar; release holes are arranged between the first bus bar and the second bus bar, the release holes penetrate through the piezoelectric layer and communicate with the air cavity; in the first direction, the distance x between the release hole and the midpoint of the aperture of the interdigital electrode satisfies the following condition: x≤0.25W; in a second direction, the distance Δy between adjacent release holes satisfies the following condition: where p is half of the period length of the interdigital electrode, W is the length of the aperture of the interdigital electrode, the length of the aperture of the interdigital electrode is the length of the overlapping region of the fingers on the first bus bar and the fingers on the second bus bar in the first direction, the first direction is the extending direction of the fingers of the interdigital electrode, the second direction is a direction perpendicular to the first direction, and the size of the release hole is smaller than the length of the aperture of the interdigital electrode.

[0006] Based on the above technical solution, by arranging release holes between the first bus bar and the second bus bar of the interdigital electrode, injecting an etching material into the release holes and then etching the substrate, the volume of the air cavity after etching can be effectively reduced, thereby improving the mechanical strength and power tolerance of the filter, reducing the size of the filter, and reducing the difficulty of subsequent processing.

[0007] Combined with the first aspect, in some implementation manners of the first aspect, the size of the release hole is larger than the width of the finger bar.

[0008] Combined with the first aspect, in some implementation manners of the first aspect, the value of W is greater than or equal to 10 μm and less than or equal to 150 μm.

[0009] Combined with the first aspect, in some implementation manners of the first aspect, the value of p is greater than or equal to 600 nm and less than or equal to 10 μm.

[0010] Combined with the first aspect, in some implementation manners of the first aspect, the width of the finger bar is greater than or equal to 200 nm and less than or equal to 2 μm.

[0011] Combined with the first aspect, in some implementation manners of the first aspect, the area of the release hole is greater than or equal to 9 μm 2 。

[0012] Combined with the first aspect, in some implementation manners of the first aspect, the release hole includes a first release hole, the first release hole is arranged in the area between the finger bars of the interdigital electrode, and the size of the first release hole in the second direction is smaller than the distance between adjacent finger bars of the interdigital electrode.

[0013] Based on the above technical solution, by arranging the first release holes between the finger bars of the interdigital electrode, while the finger bars can be effectively supported, the substrate below the area of the interdigital electrode can also be released.

[0014] Combined with the first aspect, in some implementation manners of the first aspect, the value of x is 0, in the second direction, there is a finger bar of the interdigital electrode between adjacent first release holes, and the value of p is greater than or equal to 3 μm and less than or equal to 10 μm.

[0015] Based on the above technical solution, the first release holes are arranged between adjacent finger bars of the interdigital electrode, and the first release holes are arranged at the midpoint of the aperture of the interdigital electrode in the first direction, so that when the finger bar spacing is large, the substrate below the area of the interdigital electrode can also be fully released, and the substrate below the non-interdigital electrode area is not released.

[0016] In combination with the first aspect, in some implementations of the first aspect, in the second direction, there are at least two finger bars of the interdigital electrodes spaced between adjacent first release holes.

[0017] Based on the above technical solution, arranging the first release holes with at least two finger bars spaced therebetween makes the arrangement of the first release holes not overly dense, further improving the mechanical strength of the filter.

[0018] In combination with the first aspect, in some implementations of the first aspect, the value of x is 0, and in the second direction, there are three finger bars of the interdigital electrodes spaced between adjacent first release holes.

[0019] Based on the above technical solution, arranging the first release holes with three finger bars spaced therebetween and having the first release holes arranged at the midpoints of the apertures of the interdigital electrodes in the first direction makes the arrangement of the first release holes not overly dense, further improving the mechanical strength of the filter.

[0020] In combination with the first aspect, in some implementations of the first aspect, in the second direction, a first distance between the finger bars adjacent to the first release holes is greater than a second distance between adjacent finger bars when no first release hole is provided therebetween. Based on the above technical solution, after appropriately adjusting the distance between some finger bars, large-sized first release holes can be accommodated, enabling the substrate below the interdigital electrode region to be fully released while the substrate below the non-interdigital electrode region is not released.

[0021] In combination with the first aspect, in some implementations of the first aspect, the value of x is 0, and the value of p is greater than or equal to 600 nm and less than 3 μm.

[0022] Based on the above technical solution, when it is difficult to arrange the first release holes due to the close distance between the finger bars of the interdigital electrodes, after appropriately adjusting the distance between some finger bars, large-sized first release holes can be accommodated, and the first release holes are arranged at the midpoints of the apertures of the interdigital electrodes in the first direction, enabling the substrate below the interdigital electrode region to be fully released while the substrate below the non-interdigital electrode region is not released.

[0023] In combination with the first aspect, in some implementations of the first aspect, the release holes further include second release holes that penetrate through the finger bars of the interdigital electrodes.

[0024] Based on the above technical solution, when it is difficult to arrange the first release holes due to the close distance between the finger bars of the interdigital electrodes, providing second release holes that penetrate through the finger bars of the interdigital electrodes can enable the substrate below the interdigital electrode region to be fully released while the substrate below the non-interdigital electrode region is not released.

[0025] In combination with the first aspect, in certain implementations of the first aspect, in the second direction, there are at least two finger bars of the interdigital electrodes spaced between adjacent second release holes.

[0026] Based on the above technical solution, arranging the second release holes with at least two finger bars spaced therebetween makes the arrangement of the second release holes not too dense, further improving the mechanical strength of the filter.

[0027] In combination with the first aspect, in certain implementations of the first aspect, the value of x is 0. In the second direction, there are three finger bars of the interdigital electrodes spaced between adjacent second release holes, and the value of p is greater than or equal to 600 nm and less than 3 μm.

[0028] Based on the above technical solution, arranging the second release holes with three finger bars spaced therebetween, and all the second release holes are arranged at the midpoints of the apertures of the interdigital electrodes in the first direction, makes the arrangement of the second release holes not too dense, further improving the mechanical strength of the filter.

[0029] In combination with the first aspect, in certain implementations of the first aspect, it further includes: a dielectric layer, the dielectric layer is disposed below the piezoelectric layer, the release hole penetrates through the dielectric layer, and the thickness of the dielectric layer is greater than or equal to 100 nm and less than or equal to 2 μm.

[0030] In combination with the first aspect, in certain implementations of the first aspect, it further includes: a bottom electrode layer, the bottom electrode layer is disposed above the substrate, and the release hole penetrates through the bottom electrode layer.

[0031] In combination with the first aspect, in certain implementations of the first aspect, the substrate further includes: a release layer, the release layer is disposed above the substrate, and the thickness of the substrate is greater than or equal to 50 μm and less than or equal to 1000 μm.

[0032] In combination with the first aspect, in certain implementations of the first aspect, the material of the release layer is polysilicon.

[0033] In combination with the first aspect, in certain implementations of the first aspect, the release hole is a circular release hole, and the diameter of the circular release hole is greater than or equal to 3.4 μm.

[0034] In combination with the first aspect, in certain implementations of the first aspect, the release hole is an oval release hole, and the length of the minor axis of the oval release hole is greater than or equal to 3.4 μm.

[0035] In combination with the first aspect, in certain implementations of the first aspect, the release hole is a quadrilateral release hole, and the length of the short side of the quadrilateral release hole is greater than or equal to 3 μm.

[0036] In combination with the first aspect, in some implementations of the first aspect, the release hole is a polygonal release hole.

[0037] In combination with the first aspect, in some implementations of the first aspect, the thickness of the piezoelectric layer is greater than or equal to 100 nm and less than or equal to 1 μm.

[0038] In combination with the first aspect, in some implementations of the first aspect, the thickness of the interdigital electrode is greater than or equal to 50 nm and less than or equal to 1 μm.

[0039] In combination with the first aspect, in some implementations of the first aspect, a plurality of the interdigital electrodes are included, at least one of the first busbars is connected to a signal input terminal, and at least one of the second busbars is connected to a signal output terminal.

[0040] In a second aspect, a radio frequency chip is provided, including a processor and a filter, the processor is coupled to the filter, and the filter is the filter as described in the first aspect and any possible implementations thereof.

[0041] In a third aspect, an electronic device is provided, including a filter and a circuit board, the filter is disposed on the circuit board, and the filter is the filter as described in the first aspect and any possible implementations thereof.

[0042] In a fourth aspect, a method for manufacturing a filter is provided, and the manufacturing method is used to manufacture the filter as described in the first aspect and any possible implementations thereof. Description of the Drawings

[0043] Figure 1 is a schematic diagram of the framework of an electronic device provided by an embodiment of the present application.

[0044] Figure 2 is a schematic diagram of the structure of a filter provided by an embodiment of the present application.

[0045] Figure 3 is a schematic cross-sectional view of a filter provided by an embodiment of the present application.

[0046] Figure 4 is a top view of a filter provided by an embodiment of the present application.

[0047] Figure 5 is a top view of another filter provided by an embodiment of the present application.

[0048] Figure 6 is a top view of another filter provided by an embodiment of the present application.

[0049] Figure 7 is a top view of another filter provided by an embodiment of the present application.

[0050] Figure 8 It is a top view of another filter provided by an embodiment of the present application.

[0051] Figure 9 It is a schematic cross-sectional view of another filter provided by an embodiment of the present application.

[0052] Figure 10 It is a schematic cross-sectional view of another filter provided by an embodiment of the present application.

[0053] Figure 11 It is a schematic cross-sectional view of another filter provided by an embodiment of the present application.

[0054] Figure 12 It is a schematic flow chart of a method for manufacturing a filter provided by an embodiment of the present application. Detailed implementation manners

[0055] Next, the technical solutions in the present application will be described with reference to the accompanying drawings. It should be understood that the specific examples in this specification are only for helping those skilled in the art better understand the embodiments of the present application, rather than limiting the scope of the embodiments of the present application.

[0056] It should also be understood that the various implementation manners described in this specification can be implemented alone or in combination, and the embodiments of the present application do not make any limitations in this regard.

[0057] Unless otherwise specified, all technical and scientific terms used in the embodiments of the present application have the same meaning as commonly understood by those skilled in the technical field of the present application. The terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the scope of the present application.

[0058] The terms "comprise", "include", "have" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0059] Unless otherwise defined, the technical terms or scientific terms used herein should have the ordinary meaning as understood by those of ordinary skill in the technical field to which the present application belongs. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application 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, and therefore cannot be understood as a limitation to the present application.

[0060] Before formally introducing the embodiments of the present application, the terms that may be used in the embodiments of the present application are first described.

[0061] An interdigital transducer (IDT), also known as an interdigital transducer, is a device composed of two interlocking comb-shaped metal electrode arrays. These metal electrodes are deposited on the surface of a piezoelectric layer (such as quartz or lithium niobate) to form a periodic structure.

[0062] Bus bar: A bus electrode used to connect the finger bars of the IDT interdigital electrodes to achieve electrical connection between the functional area of the IDT interdigital electrodes and the outside.

[0063] The embodiments of the present application provide an electronic device. The electronic device is, for example, a consumer electronic product, a home electronic product, a vehicle-mounted electronic product, a financial terminal product, or a communication electronic product. Among them, consumer electronic products such as mobile phones, tablets, laptop computers, e-readers, personal computers (PCs), personal digital assistants (PDAs), desktop monitors, smart wearable products (such as smart watches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, drones, etc. Home electronic products such as smart door locks, TVs, remote controls, refrigerators, charging household small appliances (such as soybean milk makers, floor sweeping robots), etc. Vehicle-mounted electronic products such as vehicle-mounted navigators, vehicle-mounted high-density digital video discs (DVDs), etc. Financial terminal products such as automated teller machines (ATMs), terminals for self-service business handling, etc. Communication electronic products such as communication devices such as servers, memories, radars, base stations, etc.

[0064] For the convenience of description below, the electronic device is taken as an example of a mobile phone for illustration. As Figure 1 shown, the electronic device 1 mainly includes a cover plate 11, a display screen 12, a middle frame 13, and a rear shell 14. The rear shell 14 and the display screen 12 are respectively located on both sides of the middle frame 13, and the middle frame 13 and the display screen 12 are arranged inside the rear shell 14. The cover plate 11 is arranged on the side of the display screen 12 away from the middle frame 13, and the display surface of the display screen 12 faces the cover plate 11.

[0065] The above display screen 12 can be a liquid crystal display (LCD). In this case, the liquid crystal display includes a liquid crystal display panel and a backlight module. The liquid crystal display panel is disposed between the cover plate 11 and the backlight module, and the backlight module is used to provide light source for the liquid crystal display panel. The above display screen 12 can also be an organic light emitting diode (OLED) display screen. Since the OLED display screen is a self-luminous display screen, there is no need to provide a backlight module.

[0066] The above middle frame 13 includes a carrier plate 131 and a frame 132 surrounding the carrier plate 131 for one week. The above electronic device 1 may further include electronic components such as printed circuit boards (PCBs), batteries, cameras, etc. The electronic components such as printed circuit boards, batteries, cameras, etc. can be disposed on the carrier plate 131.

[0067] The above electronic device 1 may further include a system on chip (SOC), a radio frequency chip, etc. disposed on the PCB. The PCB is used to carry the system on chip, the radio frequency chip, etc., and is electrically connected to the system on chip, the radio frequency chip, etc. Among them, the radio frequency chip may include parts such as a filter, a processor, etc. The processor is used to process various signals. The filter is an important part of radio frequency signal processing, and is used to pass signals of a specific frequency and block signals of other frequencies.

[0068] An embodiment of the present application provides a filter, which can be applied to the above electronic device 1, for example, applied to the radio frequency chip in the electronic device 1. The filter provided by the embodiment of the present application can be, for example, a low-pass filter, a high-pass filter, a band-pass filter, a band-stop filter or an active filter, etc.

[0069] Of course, the filter provided by the embodiment of the present application is not limited to being integrated in the electronic device 1. The filter can also be used as a single component alone, or the filter can be integrated with components such as a power amplifier into a module (such as a radio frequency device, a radio frequency module, a filter module, etc.). The filter is coupled to the power amplifier for signal processing and transmission.

[0070] As Figure 2 shown, the filter 10 provided by the embodiment of the present application includes a plurality of cascaded resonators 100. The plurality of resonators 100 can have different resonant frequencies and can be cascaded together in a series-parallel manner. Referring to Figure 2 , when the plurality of resonators 100 are cascaded together in a series-parallel manner, Figure 2 the signal input terminal Vi, the signal output terminal Vo and the ground terminal GND of the filter 10 are also shown.

[0071] During the manufacturing process of a cavity type surface acoustic wave filter, it is necessary to etch release holes on the upper surface of the device, and then inject an etching material through the release holes to locally etch the substrate, so that the interdigital electrode area is suspended. Currently, the release holes are often placed in the area between the finger tips of the interdigital electrodes and the bus bar. However, when etching the release holes placed in this way, the substrate in the non-interdigital electrode area will also be etched away, resulting in an overly large air cavity formed after release and reducing the mechanical strength of the device. Therefore, a filter with a small release cavity and high mechanical strength is needed.

[0072] In view of this, an embodiment of the present application provides a filter, the size of the release cavity of which can be effectively limited, thereby improving the mechanical strength and power tolerance of the device, reducing the difficulty of subsequent processing, and at the same time reducing the size of the filter.

[0073] Figure 3 It is a cross-sectional schematic diagram of a filter provided by an embodiment of the present application.

[0074] As Figure 3 shown, the filter 10 is arranged with a substrate 101 from bottom to top in sequence, and the substrate 101 has an air cavity 1011; a piezoelectric layer 102 located above the substrate; an interdigital electrode 103 located above the piezoelectric layer 102, and the interdigital electrode 103 includes a first bus bar 1031 and a second bus bar 1032 that are parallel to each other ( Figure 3 not shown, reference can be made to Figure 4 ). A release hole 104 is arranged between the first bus bar 1031 and the second bus bar 1032, and the release hole 104 penetrates through the piezoelectric layer 102 and communicates with the air cavity 1011.

[0075] In some embodiments provided by the present application, the air cavity 1011 of the substrate 101 can be formed by injecting an etching material into the substrate 101 through the release hole 104, and the air cavity 1011 can be an overlap of multiple hemispherical cavities.

[0076] The air cavity 1011 is formed in the substrate 101 below the interdigital electrode 103, suspending the interdigital electrode 103, so that the acoustic wave energy is limited in the piezoelectric layer 102 as much as possible, improving the quality factor of the filter 10.

[0077] In some embodiments, the finger width of the interdigital electrode 103 can be greater than or equal to 200 nm and less than or equal to 2 μm. For example, the finger width of the interdigital electrode 103 can be 300 nm, 500 nm, 800 nm, 1 μm, 1.5 μm or 1.8 μm.

[0078] In some embodiments, the period length of the interdigital electrode 103 can be greater than or equal to 1.2 μm and less than or equal to 20 μm. For example, the period length of the interdigital electrode 103 can be 1.4 μm, 1.6 μm, 2 μm, 3 μm, 5 μm, 10 μm, or 15 μm.

[0079] In some embodiments, the material of the substrate 101 can include any one of materials such as silicon, silicon carbide, quartz, sapphire, diamond, lithium niobate, lithium tantalate, etc.

[0080] In some embodiments, the material of the piezoelectric layer 102 can include any one of materials such as lithium niobate, lithium tantalate, aluminum nitride, zinc oxide, quartz, etc.

[0081] In some embodiments, the material of the interdigital electrode 103 can include any one of metal materials such as aluminum, copper, molybdenum, silver, gold, chromium, ruthenium, rhodium, etc. or any one of alloy materials composed of the above metal materials.

[0082] Figure 4 is a top view of a filter provided by an embodiment of the present application.

[0083] Release holes 104 are arranged between the fingers of each interdigital electrode 103 of the filter 10. In the figure, the X direction represents the first direction, and the Y direction represents the second direction. In the figure, p represents half of the period length of the interdigital electrode 103, and p satisfies the condition: 600 nm ≤ p ≤ 10 μm. In the figure, W represents the length of the aperture of the interdigital electrode 103, and W satisfies the condition: 10 μm ≤ W ≤ 150 μm.

[0084] In some embodiments, the value of W can be 15 μm, 20 μm, 50 μm, 75 μm, 100 μm, 120 μm, or 140 μm.

[0085] In some embodiments, the value of p can be 700 nm, 800 nm, 1 μm, 1.5 μm, 2.5 μm, 5 μm, or 7.5 μm.

[0086] The period length of the interdigital electrode 103 refers to twice the sum of the width of a single finger and the distance between adjacent fingers; this period length can be a preset period length determined when designing the interdigital electrode 103. For example, when there are no release holes 104 arranged between adjacent fingers, the value of p is the sum of the distance between adjacent fingers and the width of a single finger, and twice p is the period length of the interdigital electrode 103. The period length of the interdigital electrode 103 is related to the resonant wavelength when the filter 10 operates. The length of the overlapping region in the first direction between the fingers on the first bus bar 1031 and the fingers on the second bus bar 1032 is called the aperture length of the interdigital electrode, as Figure 4 the length shown by W in

[0087] In the first direction, the distance x between the release hole 104 and the midpoint of the aperture of the interdigital electrode 103 satisfies the condition: x ≤ 0.25W, as Figure 4 shown, where x represents the distance between the release hole 104a and the midpoint of the aperture of the interdigital electrode 103. For example, the value of x can be 0, 0.05W, 0.1W, 0.15W, or 0.2W.

[0088] Δy represents the distance between two adjacent release holes 104 in the second direction, as Figure 4 shown. Δy should satisfy the condition: p ≤ Δy ≤ √3W.

[0089] In some embodiments, the area of each release hole 104 is greater than or equal to 9μm 2 ; the size of the release hole 104 is greater than the width of the finger bars of the interdigital electrode 103.

[0090] In one possible implementation, the shape of the release hole 104 is circular, and the diameter of the circular release hole 104 is greater than or equal to 3.4μm.

[0091] In one possible implementation, the shape of the release hole 104 is oval, and the length of the minor axis of the oval release hole 104 is greater than or equal to 3.4μm.

[0092] In one possible implementation, the shape of the release hole 104 is quadrilateral, and the length of the shorter side of the quadrilateral release hole 104 is greater than or equal to 3μm.

[0093] In one possible implementation, the shape of the release hole 104 is polygonal, and the area of the polygonal release hole 104 is greater than or equal to 9μm 2 ; the shape of the release hole 104 can also be an irregular-shaped hole, and the area of the irregular-shaped hole is also greater than or equal to 9μm 2 .

[0094] As Figure 4 shown, the release hole 104 can include a first release hole 1041 and a second release hole 1042. The first release hole 1041 is arranged in the area between the finger bars of the interdigital electrode 103, and the second release hole 1042 is disposed through the finger bars of the interdigital electrode 103.

[0095] In one possible implementation, the filter 10 can be provided only with the first release hole 1041 arranged in the area between the finger bars of the interdigital electrode 103, or only with the second release hole 1042 disposed through the finger bars of the interdigital electrode 103; the filter 10 can also be provided with both the first release hole 1041 and the second release hole 1042. The embodiments of the present application do not make any limitations in this regard.

[0096] As shown Figure 4 in the figure, between the fingers of adjacent interdigital electrodes 103, the number of release holes 104 arranged can be multiple or one.

[0097] In some embodiments, only one first release hole 1041 can be arranged between the fingers of adjacent interdigital electrodes 103, or three first release holes 1041 can be arranged, or a larger number of first release holes 1041 can be arranged. No first release hole 1041 may be arranged between some fingers. Embodiments of the present application do not limit this.

[0098] In some embodiments, only one second release hole 1042 can be arranged on the fingers of the interdigital electrode 103, or three second release holes 1042 can be arranged, or a larger number of second release holes 1042 can be arranged. No second release hole 1042 may be arranged on some fingers. Embodiments of the present application do not limit this.

[0099] As shown Figure 4 in the figure, in the second direction, if the distance Δy between adjacent release holes 104 is too small, it will cause the release holes 104 in the filter 10 to be arranged too densely, resulting in a decrease in the mechanical strength of the filter 10; since the area of the substrate 101 that each release hole 104 can release is limited after injecting the etching material into the release hole 104, if Δy is too large, it will cause insufficient release of the substrate 101 and an inappropriate air cavity 1011 cannot be formed, affecting the performance of the filter 10. Therefore, Δy should satisfy the condition: This can enable the filter 10 to have reliable mechanical strength while completely releasing the area of the substrate 101 that needs to be released, making the area of the interdigital electrode 103 suspended.

[0100] Based on the above technical solution, by penetratingly arranging release holes 104 in some areas between the fingers of the interdigital electrode 103 and / or on the fingers, and etching the substrate 101 after injecting the etching material into the release holes 104, the area of the substrate 101 to be released can be effectively limited below the interdigital electrode 103, so that the substrate 101 below the non-interdigital electrode 103 area is not etched, improving the mechanical strength of the filter 10.

[0101] In some embodiments, the distance between the fingers of the interdigital electrode 103 may be relatively large. To fully release the substrate below the interdigital electrode 103, first release holes 1041 can be arranged between adjacent fingers. One first release hole 1041 or multiple first release holes 1041 can be arranged between adjacent fingers. Embodiments of the present application do not limit this.

[0102] In a possible implementation, in the first direction, the position of each first release hole 1041 may satisfy x = 0. At this time, the first release hole 1041 is located at the midpoint of the aperture of the interdigital electrode 103. For example Figure 4 the release hole 104b in Figure 4 is located at the midpoint of the aperture of the interdigital electrode 103. Alternatively, the position of some of the first release holes 1041 satisfies x = 0.25W. At this time, the position where the first release holes 1041 are arranged may be close to the first bus bar 1031 or close to the second bus bar 1032. For example

[0103] Figure 5 is a top view of another filter provided by an embodiment of the present application.

[0104] As Figure 5 shown, the first release holes 1041 are arranged between the fingers of each interdigital electrode 103. Only one first release hole 1041 is arranged between each pair of fingers. In the first direction, x = 0; in the second direction, there is an interdigital electrode 103 finger interval between adjacent first release holes 1041. The value of p is greater than or equal to 3μm and less than or equal to 10μm.

[0105] Based on the above technical solution, the first release holes 1041 are arranged between adjacent fingers, so that in the case of a relatively long period length, a partial area of the substrate 101 under the interdigital electrode 103 can be fully released, ensuring that the interdigital electrode 103 can be suspended.

[0106] In some embodiments, the first release holes 1041 are not arranged between the fingers of every two interdigital electrodes 103, but are arranged at intervals of a certain number of fingers of the interdigital electrodes. For example, the first release holes 1041 can be arranged at intervals of two fingers, or at intervals of three fingers, or at intervals of more fingers. In the first direction, the position of the first release holes 1041 only needs to satisfy the condition x ≤ 0.25W. In the second direction, the distance between adjacent first release holes 1041 still satisfies the condition:

[0107]

[0108] In a possible implementation, one first release hole 1041 or multiple first release holes 1041 may be arranged between adjacent finger bars, and the embodiments of the present application do not limit this.

[0109] Figure 6 is a top view of another filter provided by an embodiment of the present application.

[0110] As Figure 6 shown, in the first direction, x = 0; in the second direction, there are three finger bars of the interdigital electrode 103 spaced between adjacent first release holes 1041.

[0111] Figure 6 The dashed area 1011a in

[0112] indicates the area of the air cavity 1011 formed after etching the etching material of the filter 10. It can be seen that the air cavity 1011 is mainly formed below the area of the interdigital electrode 103 and does not release the substrate 101 below the non-interdigital electrode area. The filter 10 provided by the embodiment of the present application can effectively reduce the volume of the air cavity 1011, improve the mechanical strength of the filter 10, and reduce the size of the filter 10.

[0113] In a possible implementation, one first release hole 1041 or multiple first release holes 1041 may be arranged between adjacent finger bars, and the embodiments of the present application do not limit this.

[0114] In a possible implementation, the first release hole 1041 may be arranged with two finger bars spaced therebetween, or with three finger bars spaced therebetween, or the first release holes 1041 may be arranged with more finger bars spaced therebetween, and the embodiments of the present application do not limit this.

[0115] Figure 7 is a top view of another filter provided by an embodiment of the present application.

[0116] As shown Figure 7 in the first direction, x = 0; the first distance D1 between the finger bars adjacent to the first release hole 1041 is greater than the second distance D2 when there is no first release hole 1041 between other finger bars. Such a setting facilitates accommodating a first release hole 1041 with a larger size. In the second direction, the distance between adjacent first release holes 1041 still satisfies the condition that the value of p can be greater than or equal to 600 nm and less than 3 μm.

[0117] It should be understood that in the above technical solution, the distances between the finger bars of the interdigital electrode 103 are not exactly equal, but this does not mean that the period length of the interdigital electrode 103 has changed. The p value shown in the figure still represents half of the period length of the interdigital electrode 103. Or rather, the sum of the second distance D2 between the adjacent finger bars without the release hole 104 and the width of the finger bar is half of the period length of the interdigital electrode 103. That is to say, when the distances between the adjacent finger bars of the interdigital electrode 103 are not exactly equal, the p value is the sum of the second distance D2 and the width of the finger bar. Increasing the distances between some of the finger bars of the interdigital electrode 103 is an adaptive adjustment to accommodate a first release hole 1041 with a larger size and will not affect the period length of the interdigital electrode 103. The period length of the interdigital electrode 103 can be a fixed value.

[0118] Based on the above technical solution, by increasing the first distance between the finger bars adjacent to the first release hole 1041, a first release hole 1041 with a larger size can be arranged between the finger bars of the interdigital electrode 103, effectively improving the speed of releasing the substrate.

[0119] In some embodiments, the finger bars of the interdigital electrode 103 may be arranged densely, the distances between the finger bars are small, and it is difficult to arrange a first release hole 1041 with a suitable size between the finger bars. In this case, the second release hole 1042 can be arranged through the finger bars of the interdigital electrode 103. For example, after truncating the finger bars of the interdigital electrode 103, the second release hole 1042 is arranged at the position where the finger bars of the interdigital electrode 103 are truncated. Arranging through means that the second release hole 1042 is arranged after completely truncating the finger bar. In the first direction, the position of the second release hole 1042 satisfies the condition x ≤ 0.25W. In the second direction, the distance between adjacent second release holes 1042 still satisfies the condition that

[0120] In a possible implementation manner, the second release hole 1042 can be arranged with an interval of two finger bars, or with an interval of three finger bars, or the second release hole 1042 can be arranged with an interval of more finger bars. The embodiments of the present application do not limit this.

[0121] In a possible implementation, a second release hole 1042 may be provided through the finger bars of the interdigital electrode 103, or multiple second release holes 1042 may be provided through the finger bars. The embodiments of the present application do not limit this.

[0122] Figure 8 It is a top view of another filter provided by the embodiments of the present application.

[0123] As Figure 8 shown, a second release hole 1042 is provided through the finger bars of the interdigital electrode 103; in the first direction, x = 0, and in the second direction, the distance between adjacent second release holes 1042 still satisfies the condition: There are three finger bars of the interdigital electrode 103 between adjacent second release holes 1042. The value of p is greater than or equal to 600 nm and less than 3 μm.

[0124] Based on the above technical solution, when the value of p of the interdigital electrode 103 is small, arranging the second release holes 1042 through the finger bars of the interdigital electrode 103 can enable the substrate 101 below the area of the interdigital electrode 103 to be fully released, and the substrate below the non-interdigital electrode 103 area is not released.

[0125] Figure 9 It is a side view of another filter provided by the embodiments of the present application.

[0126] As Figure 9 shown, the filter 10 is further provided with a dielectric layer 102a (or referred to as a dielectric material layer), and the dielectric layer 102a is provided below the piezoelectric layer 102, and the release hole 104 penetrates through the dielectric layer 102a.

[0127] In some embodiments, the material of the dielectric layer 102a may include any one of materials such as silicon dioxide, silicon nitride, sapphire, etc.

[0128] In some embodiments, the dielectric layer 102a may be prepared by physical vapor deposition (PVD) or chemical vapor deposition (CVD). The embodiments of the present application do not limit this.

[0129] The dielectric layer 102a can provide electrical isolation between different parts of the filter 10, and can also protect the filter 10 from chemical corrosion.

[0130] Silicon dioxide has good electrical insulation, thermal stability and chemical stability; silicon nitride has strong corrosion resistance and can block impurities during diffusion and implantation; sapphire, that is, aluminum oxide, has relatively low leakage current and good thermal / electrical stability.

[0131] Figure 10 It is a side view of another filter provided by an embodiment of the present application.

[0132] As Figure 10 shown, a release layer 101a is further provided on the substrate 101 of the filter 10, and the release layer 101a is provided above the substrate 101. In this case, the air cavity 1011 is formed by injecting an etching material into the release layer 101a through the release hole 104.

[0133] In a possible implementation manner, the material of the release layer 101a is polysilicon. The purpose of providing the release layer 101a is to be able to form the air cavity 1011 faster in the release layer 101a when injecting the etching material into the substrate 101 through the release hole 104. The material of the release layer 101a is related to the choice of the etching material, and a reaction should easily occur between the etching material and the material of the release layer 101a to facilitate accelerating the release speed.

[0134] It should be understood that when the substrate 101 is not provided with the release layer 101a, the air cavity 1011 is directly formed in the substrate 101; when the release layer 101a is provided, the air cavity 1011 is formed in the release layer 101a.

[0135] Figure 11 It is a side view of another filter provided by an embodiment of the present application.

[0136] As Figure 11 shown, the filter 10 is further provided with a bottom electrode layer 105, the bottom electrode layer 105 is provided above the substrate 101, and the release hole 104 penetrates through the bottom electrode layer 105.

[0137] It should be understood that when the filter 10 is provided with the release layer 101a, the bottom electrode layer 105 is provided above the release layer 101a.

[0138] In some embodiments, the material of the bottom electrode layer 105 may include any one of metal materials such as aluminum, copper, molybdenum, silver, gold, chromium, ruthenium, rhodium, etc. or any one of alloy materials composed of the above metal materials.

[0139] Figure 12 It is a schematic flowchart of a preparation method of a filter 10 provided by an embodiment of the present application.

[0140] This method is used to prepare any one of the filters described in any of the above embodiments.

[0141] As Figure 12 shown, this preparation method may include:

[0142] S1201: Obtain a substrate.

[0143] In the embodiments provided by the present application, the material used to prepare the substrate 101 may include any one of materials such as silicon, silicon carbide, quartz, sapphire, diamond, lithium niobate, lithium tantalate, etc.

[0144] In some embodiments, the substrate 101 may further include a release layer 101a, and the release layer 101a is located above the substrate 101. The material used to prepare the release layer 101a may be polysilicon.

[0145] In a possible implementation manner, a bottom electrode layer 105 may also be prepared above the substrate 101. The material used to prepare the bottom electrode layer 105 may include any one of metal materials such as aluminum, copper, molybdenum, silver, gold, chromium, ruthenium, rhodium, etc. or any one of alloy materials composed of the above metal materials. It should be understood that when a release layer 101a is prepared above the substrate 101, the bottom electrode layer 105 is prepared above the release layer 101a.

[0146] S1202: Prepare a piezoelectric layer above the substrate.

[0147] In some embodiments, a dielectric layer 102a may also be prepared below the piezoelectric layer 102.

[0148] In some embodiments, the piezoelectric layer 102 and the dielectric layer 102a may be prepared by PVD or CVD.

[0149] In some embodiments, the material used to prepare the piezoelectric layer 102 may include any one of materials such as lithium niobate, lithium tantalate, aluminum nitride, zinc oxide, quartz, etc. The thickness of the prepared piezoelectric layer 102 is greater than or equal to 100 nm and less than or equal to 1 μm.

[0150] In some embodiments, the material used to prepare the dielectric layer 102a may include any one of materials such as silicon dioxide, silicon nitride, sapphire, etc. The thickness of the prepared dielectric layer 120a is greater than or equal to 100 nm and less than or equal to 2 μm.

[0151] S1203: Prepare a plurality of interdigital electrodes above the piezoelectric layer.

[0152] In some embodiments, the material used to prepare the interdigital electrode 103 may include any one of metal materials such as aluminum, copper, molybdenum, silver, gold, chromium, ruthenium, rhodium, etc. or any one of alloy materials composed of the above metal materials. The thickness of the prepared interdigital electrode 103 is greater than or equal to 50 nm and less than or equal to 1 μm.

[0153] S1204: Open a release hole between the first bus bar and the second bus bar of the interdigital electrode that meets the following conditions: In the first direction, the distance x between the release hole and the midpoint of the aperture of the interdigital electrode satisfies the condition: x ≤ 0.25W; in the second direction, the distance Δy between adjacent release holes satisfies the condition: The size of the release hole is smaller than the length of the aperture of the interdigital electrode, and the release hole penetrates the piezoelectric layer.

[0154] Wherein, p is half of the period length of the interdigital electrode 103, W is the length of the aperture of the interdigital electrode 103, the length of the aperture of the interdigital electrode 103 is the length of the overlapping area of the finger bars on the first bus bar and the finger bars on the second bus bar in the first direction, the first direction is the extending direction of the finger bars of the interdigital electrode 103, and the second direction is the direction perpendicular to the first direction.

[0155] In some embodiments, the opened release holes 104 may include first release holes 1041 opened in the area between the finger bars of the interdigital electrode 103, or may include second release holes 1042 penetrating through the finger bars of the interdigital electrode 103. The first release holes 1041 and the second release holes 1042 may also be provided on the filter 10 at the same time.

[0156] In a possible implementation manner, the size of the first release hole 1041 opened in this step in the second direction is smaller than the distance between adjacent finger bars of the interdigital electrode 103.

[0157] In a possible implementation manner, the number of the first release holes 1041 opened between adjacent finger bars of the interdigital electrode 103 may be one or multiple; the number of the second release holes 1042 penetrating through the finger bars of the interdigital electrode 103 may be one or multiple.

[0158] In a possible implementation manner, the area of the release hole 104 opened in this step is greater than or equal to 9μm 2 .

[0159] In a possible implementation manner, the release hole 104 opened in this step also satisfies the following conditions: x = 0, in the second direction, there is one finger bar of the interdigital electrode 103 between adjacent first release holes 1041, and the value of p is greater than 3μm and less than or equal to 10μm.

[0160] In a possible implementation manner, the first release hole 1041 opened in this step also satisfies the following conditions: there are at least two finger bars of the interdigital electrode 103 between adjacent first release holes 1041.

[0161] In a possible implementation, the first release hole 1041 opened in this step further satisfies the following condition: there are at least two finger bars of the interdigital electrode 103 between adjacent first release holes 1041.

[0162] In a possible implementation, the first release hole 1041 opened in this step further satisfies the following condition: the value of x is 0, and there are three finger bars of the interdigital electrode 103 between adjacent first release holes 1041.

[0163] In a possible implementation, the first release hole 1041 opened in this step further satisfies the following condition: in the second direction, the first distance between the finger bars adjacent to the first release hole 1041 is greater than the value of p.

[0164] In a possible implementation, the first release hole 1041 opened in this step further satisfies the following condition: the value of x is 0, and the value of p is greater than or equal to 600 nm and less than 3 μm.

[0165] In a possible implementation, the second release hole 1042 opened in this step further satisfies the following condition: in the second direction, there are at least two finger bars of the interdigital electrode between adjacent second release holes 1042.

[0166] In a possible implementation, the second release hole 1042 opened in this step further satisfies the following condition: the value of x is 0, in the second direction, there are three finger bars of the interdigital electrode between adjacent second release holes 1042, and the value of p is greater than or equal to 600 nm and less than 3 μm.

[0167] It should be understood that when the dielectric layer 102a and / or the bottom electrode layer 105 are prepared in the filter 10, the release hole 104 also penetrates through the dielectric layer 102a and / or the bottom electrode layer 105.

[0168] S1205: Inject an etching material into the substrate through the release hole, so that an air cavity is formed in the substrate, and the air cavity communicates with the release hole.

[0169] In some embodiments, a release layer 101a is prepared in the filter 10, and the release layer 101a is located above the substrate 101. At this time, an etching material is injected into the release layer 101a through the release hole 104, so that an air cavity 1011 communicating with the release hole 104 is formed in the release layer 101a.

[0170] Reference to "one embodiment" or "some embodiments" or the like described in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0171] In the embodiments of the present application, the same reference numeral is used to denote the same component or the same structural member. For the same structural members in the embodiments of the present application, only one of the structural members may be marked with a reference numeral in the figure as an example. It should be understood that the reference numeral is equally applicable to other identical structural members. In addition, the various components in the drawings are not drawn to scale, and the dimensions and sizes of the structural members shown in the figure are only exemplary and should not be construed as a limitation to the present application.

[0172] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims described.

Claims

1. A filter, characterized in that, Comprising: A substrate having an air cavity; A piezoelectric layer located above the substrate; Interdigital electrodes located above the piezoelectric layer, the interdigital electrodes including first and second bus bars parallel to each other, and the interdigital electrodes further including finger bars extending along a first direction from the first and second bus bars; Release holes are arranged between the first bus bar and the second bus bar, the release holes penetrate through the piezoelectric layer and communicate with the air cavity; In the first direction, the distance x between the release hole and the midpoint of the aperture of the interdigital electrode satisfies the following condition: x ≤ 0.25W; In a second direction, the distance Δy between adjacent release holes satisfies the following condition: p ≤ Δy ≤ √3W; Wherein, p is half of the period length of the interdigital electrode, W is the length of the aperture of the interdigital electrode, the length of the aperture of the interdigital electrode is the length of the overlapping region of the finger bars on the first bus bar and the finger bars on the second bus bar in the first direction, the first direction is the extending direction of the finger bars of the interdigital electrode, the second direction is a direction perpendicular to the first direction, and the size of the release hole is smaller than the length of the aperture of the interdigital electrode.

2. The filter according to claim 1, characterized in that The size of the release hole is larger than the width of the finger bar.

3. The filter according to claim 1 or 2, characterized in that, The value of W is greater than or equal to 10 μm and less than or equal to 150 μm.

4. The filter according to any one of claims 1 to 3, characterized in that The value of p is greater than or equal to 600 nm and less than or equal to 10 μm.

5. The filter according to any one of claims 1-4, characterized in that, The width of the finger bar is greater than or equal to 200 nm and less than or equal to 2 μm.

6. The filter according to any one of claims 1-5, characterized in that The area of the release hole is greater than or equal to 9 μm 2 .

7. The filter according to any one of claims 1-6, characterized in that, The release hole includes a first release hole, the first release hole is arranged in the region between the finger bars of the interdigital electrode, and the size of the first release hole in the second direction is smaller than the distance between adjacent finger bars of the interdigital electrode.

8. The filter according to claim 7, wherein The value of x is 0, in the second direction, there is one finger bar of the interdigital electrode between adjacent first release holes, and the value of p is greater than or equal to 3 μm and less than or equal to 10 μm.

9. The filter according to any one of claims 1-8, characterized in that, In the second direction, there are at least two finger bars of the interdigital electrode between adjacent first release holes.

10. The filter according to claim 9, characterized in that, The value of x is 0, in the second direction, there are three finger bars of the interdigital electrode between adjacent first release holes.

11. The filter according to any one of claims 1-7, characterized in that, In the second direction, the first distance between the finger bars adjacent to the first release hole is greater than the second distance between adjacent finger bars when the first release hole is not provided.

12. The filter according to claim 11, wherein The value of x is 0, and the value of p is greater than or equal to 600 nm and less than 3 μm.

13. The filter according to any one of claims 1-7, characterized in that The release hole further includes a second release hole, and the second release hole is arranged through the finger bars of the interdigital electrode.

14. The filter according to claim 13, wherein In the second direction, there are at least two finger bars of the interdigital electrode between adjacent second release holes.

15. The filter according to claim 14, wherein The value of x is 0, in the second direction, there are three finger bars of the interdigital electrode between adjacent second release holes, and the value of p is greater than or equal to 600 nm and less than 3 μm.

16. The filter according to any one of claims 1-15, characterized in that Further comprising: A dielectric layer, the dielectric layer is disposed below the piezoelectric layer, the release hole penetrates through the dielectric layer, and the thickness of the dielectric layer is greater than or equal to 100 nm and less than or equal to 2 μm.

17. The filter according to any one of claims 1-16, characterized in that, Further comprising: A bottom electrode layer, the bottom electrode layer is disposed above the substrate, and the release hole penetrates through the bottom electrode layer.

18. The filter according to any one of claims 1-17, characterized in that The substrate further comprises: a release layer, the release layer is disposed above the substrate, and the thickness of the substrate is greater than or equal to 50 μm and less than or equal to 1000 μm.

19. The filter according to any one of claims 1-18, characterized in that, The release hole is a circular release hole, and the diameter of the circular release hole is greater than or equal to 3.4 μm; Or, the release hole is an oval release hole, and the length of the minor axis of the oval release hole is greater than or equal to 3.4 μm; Or, the release hole is a quadrilateral release hole, and the length of the short side of the quadrilateral release hole is greater than or equal to 3 μm; Or, the release hole is a polygonal release hole.

20. The filter according to any one of claims 1-19, characterized in that The thickness of the piezoelectric layer is greater than or equal to 100 nm and less than or equal to 1 μm.

21. The filter according to any one of claims 1-20, characterized in that, The thickness of the interdigital electrode is greater than or equal to 50 nm and less than or equal to 1 μm.

22. The filter according to any one of claims 1-21, characterized in that, Comprising a plurality of the interdigital electrodes, at least one of the first bus bars is connected to the signal input terminal, and at least one of the second bus bars is connected to the signal output terminal.

23. A radio frequency chip, characterized in that, Comprising a processor and a filter, the processor is coupled to the filter, and the filter is the filter according to any one of claims 1-22.

24. An electronic device, characterized in that, Comprising a filter and a circuit board, the filter is disposed on the circuit board, and the filter is the filter according to any one of claims 1-22.

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