Film bulk acoustic resonator, preparation method thereof and filter

Abstract

The invention discloses a film bulk acoustic resonator, a preparation method thereof and a filter, and the film bulk acoustic resonator comprises a substrate; a cavity is formed in the top of the substrate; a stack structure located at the top of the substrate; the stacked structure comprises a temperature compensation layer and an air reflection structure; the air reflection structure is located on the side, away from the substrate, of the temperature compensation layer. The temperature compensation layer is provided with a first sound reflection structure; the air reflection structure is provided with a second sound reflection structure; the orthographic projection of the first sound reflection structure and the orthographic projection of the second sound reflection structure on the substrate coincide. According to the technical scheme, transverse sound waves can be reflected while the temperature drift of the resonator is reduced, so that the sound energy loss is reduced, and the performance of the resonator is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and particularly to a thin film bulk acoustic resonator, a preparation method thereof, and a filter. Background Art

[0002] With the ultra-high-speed development of wireless communication technologies and the multi-functionalization of communication terminals, higher performance requirements are imposed on frequency devices operating in the radio frequency band. Compared with traditional dielectric ceramic filters and surface acoustic wave filters, filters based on thin film bulk acoustic resonators (FBARs) have a large operating frequency range (can operate well in the range of several hundred MHz to 6 - 7 GHz). Especially in high-frequency applications, FBAR-based filters have very significant advantages. For example, high frequency, low loss, low temperature drift characteristics, steep filter skirts, extremely high Q values, wide operating frequencies, high sensitivity, high resolution, high power capacity, small volume, and the preparation process is compatible with CMOS. Therefore, FBARs occupy most of the application fields of wireless communication.

[0003] However, with the change of the operating temperature, the resonant frequency of the FBAR will shift. Due to the large number of frequency bands and small adjacent channel intervals in modern communication systems, the frequency drift (temperature drift) caused by temperature may affect the signal transmission of adjacent frequency bands, thus causing signal interference. Therefore, ensuring that the FBAR device has excellent temperature stability is crucial for avoiding communication interference.

[0004] The existing methods for reducing the temperature drift of FBAR devices mainly involve adding temperature compensation materials to the FBAR device structure. Usually, a whole layer of temperature compensation material is added to the FBAR structure. However, the existing technical means will cause a significant decline in the performance of the FBAR device, easily generate parasitic modes, and seriously affect signal transmission. Summary of the Invention

[0005] The present invention provides a thin film bulk acoustic resonator, a preparation method thereof, and a filter to solve the problems existing in the prior art. While reducing the temperature drift of the resonator, it can reflect transverse acoustic waves, thereby reducing the acoustic energy loss and improving the performance of the resonator.

[0006] In a first aspect, the present invention provides a thin film bulk acoustic resonator, comprising:

[0007] A substrate; a cavity is provided at the top of the substrate;

[0008] A stacked structure located on the top of the substrate;

[0009] The stacked structure includes a temperature compensation layer and an air reflection structure; the air reflection structure is located on a side of the temperature compensation layer away from the substrate;

[0010] The temperature compensation layer is provided with a first acoustic reflection structure; the air reflection structure is provided with a second acoustic reflection structure; a positive projection of the first acoustic reflection structure on the substrate coincides with a positive projection of the second acoustic reflection structure on the substrate.

[0011] Optionally, the thin film bulk acoustic wave resonator includes an effective area;

[0012] The temperature compensation layer includes a first part and a second part; a junction of the first part and the second part is a first edge, and the first edge is parallel to an edge of the effective area; an extending direction of the first acoustic reflection structure is parallel to a part of the first edge adjacent to the first acoustic reflection structure.

[0013] Optionally, the thin film bulk acoustic wave resonator includes an effective area;

[0014] The temperature compensation layer includes a first part and a second part; a junction of the first part and the second part is a first edge, and the first edge is parallel to an edge of the effective area; the first acoustic reflection structure and the first part are arranged along a first direction; the first acoustic reflection structure extends along a second direction;

[0015] The first direction and the second direction do not coincide.

[0016] Optionally, the first direction and the second direction are perpendicular.

[0017] Optionally, the thin film bulk acoustic wave resonator includes an effective area;

[0018] The temperature compensation layer includes a first part and a second part; a junction of the first part and the second part is a first edge, and the first edge is parallel to an edge of the effective area; the first acoustic reflection structure and the first part are arranged along a first direction; the first acoustic reflection structure includes n sub-acoustic reflection structures, and the sub-acoustic reflection structures are arranged along the first direction; where n≥2 and n is an integer.

[0019] Optionally, the sub-acoustic reflection structure includes m secondary acoustic reflection structures, and the secondary acoustic reflection structures are arranged along an extending direction of the first acoustic reflection structure; where m≥1 and m is an integer.

[0020] Optionally, each of the secondary acoustic reflection structures forms a phononic crystal array.

[0021] Optionally, the stacked structure further includes:

[0022] a seed layer located on top of the substrate;

[0023] a first electrode located on top of the seed layer;

[0024] a piezoelectric layer located on top of the first electrode;

[0025] a second electrode located on top of the piezoelectric layer;

[0026] An electrode plate is located on top of the second electrode.

[0027] In a second aspect, the present invention further provides a method for preparing a thin film bulk acoustic wave resonator, comprising:

[0028] Providing a substrate; a cavity is provided on the top of the substrate;

[0029] A stacking structure is formed on the top of the substrate; wherein the stacking structure includes a temperature compensation layer and an air reflection structure; the air reflection structure is located on a side of the temperature compensation layer away from the substrate;

[0030] The temperature compensation layer is provided with a first sound reflection structure; the air reflection structure is provided with a second sound reflection structure; the first sound reflection structure and the second sound reflection structure overlap in orthographic projection on the substrate.

[0031] In a third aspect, the present invention further provides a filter, comprising: the thin film bulk acoustic wave resonator as described in any one of the above items.

[0032] The technical solution of the present invention is to make the stacked structure of the thin film bulk acoustic wave resonator include a temperature compensation layer and an air reflection structure, and the air reflection structure is located on the side of the temperature compensation layer away from the substrate, the temperature compensation layer is provided with a first sound reflection structure, and the air reflection structure is provided with a second sound reflection structure, and the first sound reflection structure and the second sound reflection structure coincide with each other in their positive projections on the substrate. Since the temperature compensation layer is provided with the first sound reflection structure, when forming a subsequent film layer, the subsequent film layer can form a second sound reflection structure located in the air reflection structure, which is conducive to simplifying the process, so that the resonator has a temperature compensation effect, and when a lateral sound wave is transmitted from the effective area of ​​the resonator, the second sound reflection structure in the air reflection structure can reflect the sound wave back, thereby reducing the leakage of sound wave energy and further improving the performance of the resonator.

[0033] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0035] Figure 1 A cross-sectional view of a thin film bulk acoustic resonator provided by an embodiment of the present invention;

[0036] Figure 2 A top view of a temperature compensation layer of a thin film bulk acoustic resonator provided by an embodiment of the present invention;

[0037] Figure 3 A top view of another temperature compensation layer provided by an embodiment of the present invention;

[0038] Figure 4 and Figure 5 Top views of two temperature compensation layers provided by an embodiment of the present invention;

[0039] Figure 6 and Figure 7 Top views of another two temperature compensation layers provided by an embodiment of the present invention;

[0040] Figure 8 and Figure 9 Top views of yet another two temperature compensation layers provided by an embodiment of the present invention;

[0041] Figure 10 A flowchart of a method for manufacturing a thin film bulk acoustic resonator provided by an embodiment of the present invention;

[0042] Figure 11 A structural schematic diagram of a filter provided by this embodiment. Detailed implementation manners

[0043] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, rather than all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here.

[0045] It should be noted that the "top" of each structure mentioned in this embodiment should be understood as the side pointed to above the thin film bulk acoustic resonator in each structure, and the "bottom" of each structure mentioned in this embodiment should be understood as the side pointed to below the thin film bulk acoustic resonator in each structure.

[0046] This embodiment provides a thin film bulk acoustic resonator, Figure 1 which is a cross-sectional view of a thin film bulk acoustic resonator provided by an embodiment of the present invention, Figure 2 which is a top view of the temperature compensation layer of a thin film bulk acoustic resonator provided by an embodiment of the present invention. With reference to Figure 1 and Figure 2 as shown, the thin film bulk acoustic resonator 1 includes: a substrate 100 and a stacked structure 10 located on the top of the substrate 100; a cavity 110 is provided on the top of the substrate 100; the stacked structure 10 includes a temperature compensation layer 150 and an air reflection structure 180; the air reflection structure 180 is located on the side of the temperature compensation layer 150 facing away from the substrate 100; the temperature compensation layer 150 is provided with a first acoustic reflection structure 151; the air reflection structure 180 is provided with a second acoustic reflection structure 190; the orthographic projection of the first acoustic reflection structure 151 and the second acoustic reflection structure 190 on the substrate 100 coincides.

[0047] Among them, after the preparation of the stacked structure 10 is completed, a cavity on the top of the substrate 100 is formed through a release hole. The cavity can confine the longitudinally propagating acoustic wave within the stacked structure 10. The stacked structure 10 includes a temperature compensation layer 150 and an air reflection structure 180, so that the resonator has a temperature compensation effect and can reduce the leakage of acoustic energy to the substrate 100, thereby improving the quality factor of the resonator. The air reflection structure 180 is located on the side of the temperature compensation layer 150 facing away from the substrate 100, and the temperature compensation layer 150 is provided with a first acoustic reflection structure 151. The orthographic projection of the first acoustic reflection structure 151 and the second acoustic reflection structure 190 on the substrate 100 coincides, so that the second acoustic reflection structure 190 can be formed in the air reflection structure 180 without further process steps, enabling the second reflection structure 190 to effectively reflect the acoustic wave signal back into the stacked structure 10, reducing the attenuation of the acoustic wave signal, thereby further reducing the leakage of acoustic energy and improving the performance of the resonator.

[0048] In an alternative embodiment, the stacked structure 10 further includes: a seed layer 120 on top of the substrate 100, a first electrode 130 on top of the seed layer 120, a piezoelectric layer 140 on top of the first electrode 130, a second electrode 160 on top of the piezoelectric layer 140, and an electrode plate 170 on top of the second electrode 160, such that when a voltage is applied between the first electrode 130 and the second electrode 160, the resonator can generate a corresponding resonance frequency.

[0049] In an alternative embodiment, an air reflection structure 180 is located between the piezoelectric layer 140 and the second electrode 160, and there are other film layers (such as Figure 1 the piezoelectric layer 140 in

[0050] between the air reflection structure 180 and the temperature compensation layer 150), and the total thickness D of the other film layers between the air reflection structure 180 and the temperature compensation layer 150 is ≥ 5 nm, so as to avoid damaging the temperature compensation layer when forming the air reflection structure, thereby causing the thin film bulk acoustic wave resonator to lose the temperature compensation effect.

[0051] It can be understood that since the positive projection of the first acoustic reflection structure 151 of the temperature compensation layer 150 and the second acoustic reflection structure 190 of the air reflection structure 180 on the substrate 100 coincides, and since the temperature compensation layer 150 is provided with the first acoustic reflection structure 151, when forming the piezoelectric layer after the temperature compensation layer 150, a similar convex structure will be formed at the position corresponding to the first acoustic reflection structure 151 in the piezoelectric layer. Since the air reflection structure 180 is located on top of the piezoelectric layer, the similar convex structure in the piezoelectric layer to the first acoustic reflection structure 151 is the second acoustic reflection structure 190 of the air reflection structure 180.

[0052] It should also be noted that the temperature compensation layer 150 can be a whole layer structure, or can be provided only above the cavity and below the air reflection structure 180, as long as the core inventive point of the present invention can be achieved.

[0053] In the present embodiment, the stacked structure of the thin film bulk acoustic wave resonator includes a temperature compensation layer and an air reflection structure, and the air reflection structure is located on the side of the temperature compensation layer away from the substrate, the temperature compensation layer is provided with a first sound reflection structure, and the air reflection structure is provided with a second sound reflection structure, and the first sound reflection structure and the second sound reflection structure coincide with each other in their orthographic projections on the substrate. Since the temperature compensation layer is provided with the first sound reflection structure, when a subsequent film layer is formed, the subsequent film layer can form a second sound reflection structure located in the air reflection structure, which is beneficial to simplifying the process, so that the resonator has a temperature compensation effect, and when a lateral sound wave is transmitted from the effective area of ​​the resonator, the second sound reflection structure in the air reflection structure can reflect the sound wave back, thereby reducing the leakage of sound wave energy and further improving the performance of the resonator.

[0054] Optional, continue to refer to Figure 2 As shown, the thin film bulk acoustic wave resonator includes an effective area; the temperature compensation layer 150 includes a first part 150a and a second part 150b, the boundary between the first part 150a and the second part 150b is a first edge a, and the first edge a is parallel to the edge of the effective area; the first sound reflection structure 151 and the first part 150a are arranged along the first direction L1, and the first sound reflection structure 151 extends along the second direction L2. Since the positive projections of the first sound reflection structure 151 and the second sound reflection structure 190 on the substrate 100 coincide, the second sound reflection structure 190 also extends along the second direction L2. By making the first direction L1 and the second direction L2 not coincide, the extension directions of the first sound reflection structure 151 and the second sound reflection structure 190 are at a certain angle to the transmission direction of the shear wave, so that the second sound reflection structure 190 can reflect the shear wave back, thereby reducing the leakage of sound wave energy.

[0055] The effective area refers to the area where the first electrode 130 and the second electrode 160 overlap in the thin film bulk acoustic wave resonator. The first direction L1 and the second direction L2 do not overlap, which means that the first direction L1 and the second direction L2 form a certain angle, including but not limited to the angle between the first direction L1 and the second direction L2 being an acute angle, an obtuse angle or a right angle. Figure 2 The case where the first direction L1 and the second direction L2 are perpendicular to each other is merely exemplified, and the first direction L1 and the second direction L2 are not limited. It is sufficient to realize the core invention of the present invention.

[0056] Optional, continue to refer to Figure 2 As shown, the first direction L1 is perpendicular to the second direction L2, so that the extension direction of the first sound reflection structure 151 and the second sound reflection structure 190 is perpendicular to the transmission direction of the transverse wave. Therefore, setting a smaller length of the second sound reflection structure 190 can transmit more transverse waves to the effective area of ​​the resonator, thereby further reducing the leakage of sound wave energy and improving the performance of the resonator.

[0057] Optionally, Figure 3 is a top view of another temperature compensation layer provided by an embodiment of the present invention. Refer to Figure 3 As shown, the extending direction of the first acoustic reflection structure 151 is parallel to a part of the first edge a adjacent to the first acoustic reflection structure 151. Since the orthographic projections of the first acoustic reflection structure 151 and the second acoustic reflection structure 190 on the substrate 100 coincide, the extending direction of the second acoustic reflection structure 190 is also parallel to the first edge a, so that when the transverse acoustic wave propagates, the air reflection structure 180 is perpendicular to the propagation directions of all transverse waves, enabling the second acoustic reflection structure 190 in the air reflection structure 180 to reflect the acoustic wave back more effectively, thereby further improving the performance of the resonator.

[0058] Optionally, refer to Figure 2 and Figure 3 As shown, the first acoustic reflection structure 151 and the first part 150a of the temperature compensation layer 150 are arranged along the first direction L1; the first acoustic reflection structure 151 includes n sub-acoustic reflection structures 1511, and each sub-acoustic reflection structure 1511 is arranged along the first direction L1.

[0059] Wherein, n≥2 and n is an integer.

[0060] Since each sub-acoustic reflection structure 1511 is arranged along the first direction L1, each sub-acoustic reflection structure 1511 can reflect the transverse wave. By setting the number of sub-acoustic reflection structures 1511 included in the first acoustic reflection structure 151 to n, the n sub-acoustic reflection structures 1511 reflect the incoming transverse wave n times, so that more transverse waves can be reflected back to the effective area of the resonator, thereby further improving the performance of the resonator.

[0061] It should be noted that Figure 2 and Figure 3 only exemplarily shows the case where the first acoustic reflection structure 151 includes 3 sub-acoustic reflection structures 1511, and does not limit the number of sub-acoustic reflection structures 1511 included in the first acoustic reflection structure 151, as long as the core inventive points of the present invention can be achieved. It can be understood that since each sub-acoustic reflection structure 1511 is arranged along the first direction L1, when the transverse wave propagates, each sub-acoustic reflection structure 1511 can reflect the transverse wave. Therefore, the more the number of sub-acoustic reflection structures 1511 included in the first acoustic reflection structure 151, the more times the transverse wave is reflected, so that more transverse waves can be reflected back to the effective area of the resonator, thereby reducing the leakage of acoustic wave energy to a greater extent. However, limited by the volume requirement and cost of the resonator, a reasonable number of sub-acoustic reflection structures 1511 can be set.

[0062] Furthermore, the sub-acoustic reflection structures 1511 are arranged along the first direction L1, and the distance between two adjacent sub-acoustic reflection structures 1511 is equal, so as to improve the reflection efficiency of the acoustic reflection structure for shear waves, and thus reflect more shear waves back to the effective area of the resonator, which can further improve the performance of the thin film bulk acoustic wave resonator.

[0063] Optionally, Figure 4 and Figure 5 are top views of two temperature compensation layers provided by embodiments of the present invention. Referring to Figure 4 and Figure 5 as shown, the sub-acoustic reflection structure 1511 includes m secondary acoustic reflection structures 1511a, and the secondary acoustic reflection structures are arranged along the extension direction of the first acoustic reflection structure 151.

[0064] Wherein, m≥1 and m is an integer. By making the sub-acoustic reflection structure 1511 include m secondary acoustic reflection structures 1511a, and the secondary acoustic reflection structures 1511a are arranged along the extension direction of the first acoustic reflection structure 151, each secondary acoustic reflection structure 1511a can reflect shear waves, so as to reflect shear waves back to the effective area of the resonator.

[0065] Furthermore, the secondary acoustic reflection structures 1511a are arranged along the extension direction of the first acoustic reflection structure 151, and the distance between two adjacent secondary acoustic reflection structures 1511a is equal, so as to improve the reflection efficiency of the acoustic reflection structure for shear waves, and thus reflect more shear waves back to the effective area of the resonator, which can further improve the performance of the thin film bulk acoustic wave resonator.

[0066] Optionally, Figure 6 and Figure 7 are top views of another two temperature compensation layers provided by embodiments of the present invention. Referring to Figure 6 and Figure 7 as shown, the secondary acoustic reflection structures 1511a form a phononic crystal array, so as to prevent the transmission of shear waves within a certain frequency range (bandgap), and propagate without loss in other frequency ranges (passband), so that the shear waves within the bandgap are reflected back to the effective area of the resonator, and the shear waves in the passband are not reflected, thereby further improving the performance of the resonator.

[0067] It should be noted that Figure 6 and Figure 7 only exemplarily show the case where the secondary acoustic reflection structures 1511a are square, and do not limit the specific shape of the secondary acoustic reflection structures 1511a. In this embodiment, the secondary acoustic reflection structures 1511a can also be other shapes such as triangles and stars, as long as the secondary acoustic reflection structures 1511a can form a phononic crystal array. Exemplarily, Figure 8 and Figure 9The top view of two more temperature compensation layers provided in the embodiment of the present invention is shown in FIG. Figure 8 and Figure 9 As shown, each secondary sound reflection structure 1511a can also be circular.

[0068] Based on the same concept, an embodiment of the present invention further provides a method for preparing a thin film bulk acoustic wave resonator. Figure 10 Flow chart of the method for preparing a thin film bulk acoustic wave resonator provided in an embodiment of the present invention, refer to Figure 10 As shown, the preparation method comprises:

[0069] S1. Provide a substrate.

[0070] The top of the substrate 100 is provided with a cavity.

[0071] In an optional embodiment, S1 may specifically include providing a clean substrate 100 , such as an SOI substrate 100 , and then forming a cavity on the top of the substrate 100 .

[0072] S2. Forming a stacking structure on top of the substrate.

[0073] Among them, the stacked structure 10 includes a temperature compensation layer 150 and an air reflection structure 180; the air reflection structure 180 is located on the side of the temperature compensation layer 150 away from the substrate 100; the temperature compensation layer 150 is provided with a first sound reflection structure 151, and the air reflection structure 180 is provided with a second sound reflection structure 190, and the first sound reflection structure 151 and the second sound reflection structure 190 coincide with their orthographic projections on the substrate 100.

[0074] In an optional embodiment, the stacked structure 10 also includes a seed layer located on top of the substrate 100; a first electrode located on top of the seed layer; a piezoelectric layer located on top of the first electrode; a second electrode located on top of the piezoelectric layer; and an electrode plate located on top of the second electrode.

[0075] In an exemplary embodiment, a temperature compensation layer 150 is located in the piezoelectric layer, and an air reflection structure 180 is located between the piezoelectric layer and the second electrode; S2 includes: forming a seed layer on the top of the substrate 100; forming a first electrode on the top of the seed layer; forming a first piezoelectric layer on the top of the first electrode; forming a temperature compensation layer 150 on the top of the first piezoelectric layer, wherein the temperature compensation layer 150 is provided with a first acoustic reflection structure 151; forming a second piezoelectric layer on the top of the first piezoelectric layer and the temperature compensation layer 150, wherein due to the presence of the first acoustic reflection structure 151, a second acoustic reflection structure 190 is formed at a position corresponding to the first acoustic reflection structure 151 in the second piezoelectric layer while the second piezoelectric layer is formed; forming a second electrode above the second piezoelectric layer, wherein an air reflection structure 180 is formed between the second piezoelectric layer and the second electrode, and the second acoustic reflection structure 190 is located within the air reflection structure 180; forming an electrode plate on the top of the second electrode.

[0076] In this embodiment, by making the stacked structure formed on the top of the substrate include a temperature compensation layer and an air reflection structure, the air reflection structure is located on a side of the temperature compensation layer away from the substrate, the temperature compensation layer is provided with a first acoustic reflection structure, the air reflection structure is provided with a second acoustic reflection structure, and the orthographic projection of the first acoustic reflection structure and the second acoustic reflection structure on the substrate coincides, so that due to the first acoustic reflection structure provided in the temperature compensation layer, when subsequent film layers are formed, a second acoustic reflection structure located in the air reflection structure can be formed in the subsequent film layers, which is beneficial to simplifying the process; at the same time, while enabling the resonator to have a temperature compensation effect, when transverse acoustic waves are transmitted from the effective area of the resonator, the second acoustic reflection structure in the air reflection structure can reflect the acoustic waves back, thereby reducing the leakage of acoustic wave energy and further improving the performance of the resonator.

[0077] Based on the same concept, an embodiment of the present invention further provides a filter. Figure 11 The following is a schematic structural diagram of a filter provided in this embodiment, with reference to Figure 11 As shown, the filter includes an input port, an output port, and a thin film bulk acoustic resonator 1 provided in any embodiment of the present invention.

[0078] In this embodiment, since the filter includes a thin film bulk acoustic resonator provided in any embodiment of the present invention, therefore, the filter can achieve the beneficial effects of the thin film bulk acoustic resonator provided in any embodiment of the present invention. The same parts can be referred to the above description and will not be elaborated here.

[0079] It should be noted that Figure 11Only the case where the filter includes 4 series thin film bulk acoustic resonators 1 and 4 parallel thin film bulk acoustic resonators 1 is shown exemplarily, and the number of thin film bulk acoustic resonators 1 in the filter is not limited. The structure of the filter in this embodiment is not limited thereto, as long as the core inventive point of this embodiment can be achieved.

[0080] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A thin film bulk acoustic wave resonator, characterized in that, include: A substrate; a cavity is provided on the top of the substrate; a stacked structure located on top of the substrate; The stacked structure comprises a temperature compensation layer and an air reflection structure; the air reflection structure is located on a side of the temperature compensation layer away from the substrate; The temperature compensation layer is provided with a first sound reflection structure; the air reflection structure is provided with a second sound reflection structure; the first sound reflection structure and the second sound reflection structure overlap in orthographic projection on the substrate.

2. The thin film bulk acoustic resonator according to claim 1, characterized in that, The thin film bulk acoustic resonator comprises an effective region; The temperature compensation layer includes a first part and a second part; the boundary between the first part and the second part is a first edge, and the first edge is parallel to the edge of the effective area; the extension direction of the first sound reflection structure is parallel to the first edge of the part adjacent to the first sound reflection structure.

3. The thin film bulk acoustic wave resonator according to claim 1, characterized in that, The thin film bulk acoustic resonator comprises an effective region; The temperature compensation layer includes a first part and a second part; the boundary between the first part and the second part is a first edge, and the first edge is parallel to the edge of the effective area; the first sound reflection structure and the first part are arranged along a first direction; the first sound reflection structure extends along a second direction; The first direction and the second direction do not overlap.

4. The thin film bulk acoustic wave resonator according to claim 3, characterized in that, The first direction and the second direction are perpendicular.

5. The thin film bulk acoustic wave resonator according to claim 1, characterized in that, The thin film bulk acoustic resonator comprises an effective region; The temperature compensation layer includes a first part and a second part; the boundary between the first part and the second part is a first edge, and the first edge is parallel to the edge of the effective area; the first sound reflection structure and the first part are arranged along a first direction; The first sound reflection structure includes n sub-sound reflection structures, and each of the sub-sound reflection structures is arranged along the first direction; wherein n≥2, and n is an integer.

6. The thin film bulk acoustic resonator according to claim 5, characterized in that, The sub-acoustic reflection structure includes m secondary acoustic reflection structures, and each of the secondary acoustic reflection structures is arranged along the extension direction of the first acoustic reflection structure; wherein m≥1, and m is an integer.

7. The thin film bulk acoustic resonator according to claim 6, wherein Each of the secondary sound reflection structures forms a phononic crystal array.

8. The thin film bulk acoustic resonator according to claim 1, wherein The stacking structure further comprises: a seed layer located on top of the substrate; a first electrode located on top of the seed layer; a piezoelectric layer located on top of the first electrode; a second electrode located on top of the piezoelectric layer; An electrode plate is located on top of the second electrode.

9. A method for preparing a thin film bulk acoustic resonator, characterized in that, include: providing a substrate; A cavity is provided on the top of the substrate; A stacking structure is formed on the top of the substrate; wherein the stacking structure includes a temperature compensation layer and an air reflection structure; the air reflection structure is located on a side of the temperature compensation layer away from the substrate; The temperature compensation layer is provided with a first sound reflection structure; the air reflection structure is provided with a second sound reflection structure; the first sound reflection structure and the second sound reflection structure overlap in orthographic projection on the substrate.

10. A filter, characterized in that, include: The thin film bulk acoustic resonator according to any one of claims 1 to 8.

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