A film bulk acoustic resonator and a method of manufacturing the same

Abstract

The application discloses a film bulk acoustic resonator and a preparation method thereof. The film bulk acoustic resonator comprises a substrate, a transducer stack structure, a temperature compensation layer and a first protruding structure. The transducer stack structure is located on one side of the substrate. The temperature compensation layer and the first protruding structure are located inside the transducer stack structure, and the first protruding structure is located on a side of the temperature compensation layer away from the substrate. The transducer stack structure comprises a working area. In the thickness direction of the film bulk acoustic resonator, the projection of the temperature compensation layer on the plane of the substrate covers the projection of the working area on the plane of the substrate. The projection of the working area on the plane of the substrate covers the projection of the first protruding structure on the plane of the substrate, and the first protruding structure is connected with the side surface of the temperature compensation layer. The technical scheme of the application reduces the frequency temperature drift of the film bulk acoustic resonator and improves the Q value of the film bulk acoustic resonator.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resonators, in particular to a film bulk acoustic resonator and a preparation method thereof. BACKGROUND

[0002] With the rapid development of wireless communication technology and the multi-function of communication terminals, frequency devices working in the radio frequency band are required to have higher performance. Compared with traditional dielectric ceramic filters and surface acoustic wave filters, filters based on film bulk acoustic resonators can work well in the range of several hundred MHz to 6-7 GHz, and have the advantages of high frequency, low loss, low temperature drift, steep filter skirt, and high Q value, operating frequency, sensitivity, resolution, and power capacity. Therefore, film bulk acoustic resonators occupy most of the application fields of wireless communication.

[0003] With the change of operating temperature, the resonant frequency of the film bulk acoustic resonator will shift. Since there are many frequency bands in modern communication systems and the adjacent channel spacing is small, the frequency drift caused by temperature may affect the signal transmission of the adjacent frequency band, thereby causing signal interference. Therefore, it is crucial to ensure that the film bulk acoustic resonator has excellent temperature stability to avoid communication interference.

[0004] The existing method for reducing the frequency drift of the film bulk acoustic resonator mainly adds a temperature compensation material in the structure of the film bulk acoustic resonator. However, the existing technical means will cause a significant decline in the performance of the film bulk acoustic resonator, and easily produce a parasitic mode, which seriously affects signal transmission. SUMMARY

[0005] The present application provides a film bulk acoustic resonator and a preparation method thereof to solve the problem of performance decline and parasitic mode caused by the introduction of a temperature compensation material in the film bulk acoustic resonator in the prior art.

[0006] According to an aspect of the present application, a film bulk acoustic resonator is provided, comprising: a substrate, a transducer stack structure, a temperature compensation layer, and a first protruding structure;

[0007] The transducer stack structure is located on one side of the substrate;

[0008] The temperature compensation layer and the first protruding structure are located inside the transducer stack structure, and the first protruding structure is located on the side of the temperature compensation layer away from the substrate, for forming a first protrusion on the surface of the transducer stack structure away from the substrate; the temperature-elasticity coefficient of the temperature compensation layer is greater than zero, and the temperature-elasticity coefficient of the transducer stack structure is less than zero;

[0009] The transducer stack structure comprises a working area; in a thickness direction of the film bulk acoustic resonator, a projection of the temperature compensation layer on a substrate plane covers a projection of the working area on the substrate plane; the projection of the working area on the substrate plane covers the projection of the first protruding structure on the substrate plane, and the first protruding structure is connected to a side surface of the temperature compensation layer.

[0010] Optionally, in the thickness direction of the film bulk acoustic resonator, the projection of the first protruding structure on the substrate plane is a closed figure.

[0011] Optionally, the transducer stack structure further comprises a second protruding structure.

[0012] The second protruding structure is arranged on a side of the temperature compensation layer away from the substrate and is spaced apart from the first protruding structure, and is used for forming a second protrusion on a surface of the transducer stack structure away from the substrate.

[0013] In the thickness direction of the film bulk acoustic resonator, the projection of the working area on the substrate plane covers the projection of the second protruding structure on the substrate plane; and the projection of the second protruding structure on the substrate plane is parallel to the projection of the first protruding structure on the substrate plane.

[0014] Optionally, the second protruding structure comprises at least two.

[0015] Each second protruding structure has the same spacing distance from the first protruding structure.

[0016] Optionally, the transducer stack structure further comprises a third protruding structure.

[0017] The third protruding structure is arranged on a side of the temperature compensation layer away from the substrate and is arranged between the first protruding structure and the second protruding structure, and is used for forming a third protrusion on a surface of the transducer stack structure away from the substrate.

[0018] In the thickness direction of the film bulk acoustic resonator, the projection of the working area on the substrate plane covers the projection of the third protruding structure on the substrate plane.

[0019] Optionally, the width of the first protruding structure is less than 10 μm.

[0020] Optionally, the transducer stack structure comprises a bottom electrode layer, a piezoelectric layer, and a top electrode layer arranged in a stack.

[0021] The temperature compensation layer is arranged in the piezoelectric layer.

[0022] According to another aspect of the present application, a preparation method of a film bulk acoustic resonator is provided, which is used for preparing a film bulk acoustic resonator; the preparation method comprises the following steps:

[0023] providing a substrate;

[0024] Preparation of the transducer stack structure, the temperature compensation layer and the first protruding structure on one side of the substrate; wherein the temperature compensation layer and the first protruding structure are located inside the transducer stack structure and the first protruding structure is located on the side of the temperature compensation layer away from the substrate; the temperature-elasticity coefficient of the temperature compensation layer is greater than zero and the temperature-elasticity coefficient of the transducer stack structure is less than zero;

[0025] The transducer stack structure comprises a working area; along the thickness direction of the film bulk acoustic resonator, the projection of the temperature compensation layer on the plane of the substrate covers the projection of the working area on the plane of the substrate; the projection of the working area on the plane of the substrate covers the projection of the first protruding structure on the plane of the substrate and the first protruding structure is connected with the side surface of the temperature compensation layer.

[0026] Optionally, the preparation of the transducer stack structure, the temperature compensation layer and the first protruding structure on one side of the substrate comprises:

[0027] Preparation of the transducer stack structure, the temperature compensation layer, the first protruding structure and the second protruding structure on one side of the substrate; wherein the second protruding structure is located on the side of the temperature compensation layer away from the substrate and is arranged in a spaced manner with the first protruding structure;

[0028] Along the thickness direction of the film bulk acoustic resonator, the projection of the working area on the plane of the substrate covers the projection of the second protruding structure on the plane of the substrate; the projection of the second protruding structure on the plane of the substrate is parallel to the projection of the first protruding structure on the plane of the substrate.

[0029] Optionally, the preparation of the transducer stack structure, the temperature compensation layer and the first protruding structure on one side of the substrate comprises:

[0030] Growth of a bottom electrode layer on one side of the substrate;

[0031] Growth of a piezoelectric layer on the side of the bottom electrode layer away from the substrate;

[0032] Growth of a temperature compensation layer on the side of the piezoelectric layer away from the bottom electrode layer;

[0033] Preparation of the first protruding structure on the side of the temperature compensation layer away from the piezoelectric layer;

[0034] Growth of the piezoelectric layer and a top electrode layer on the side of the first protruding structure away from the piezoelectric layer.

[0035] The technical scheme of the present application can form a corresponding first protrusion on the top of the film bulk acoustic resonator through the setting of the temperature compensation layer in the film bulk acoustic resonator and the setting of the first protruding structure on the temperature compensation layer and the subsequent deposition of the thin film of the stacking layer, can avoid unnecessary vibration or damping, reduce the energy loss caused by other non-resonance, reduce the frequency temperature drift of the film bulk acoustic resonator and improve the Q value of the film bulk acoustic resonator.

[0036] It is to be understood that the details set forth herein do not limit the scope of the application to the preferred embodiments described. Rather, the scope encompasses other modifications and embodiments which can be readily devised by those skilled in the art, having the benefit of the advantages of the present application due to the teachings of the present description. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative effort based on these drawings.

[0038] Figure 1 is a sectional view of a first film bulk acoustic resonator according to an embodiment of the present application;

[0039] Figure 2 is a plan view of the first film bulk acoustic resonator according to the embodiment of the present application;

[0040] Figure 3 is a sectional view of a second film bulk acoustic resonator according to an embodiment of the present application;

[0041] Figure 4 is a plan view of the second film bulk acoustic resonator according to the embodiment of the present application;

[0042] Figure 5 is a plan view of a third film bulk acoustic resonator according to an embodiment of the present application;

[0043] Figure 6 is a plan view of a fourth film bulk acoustic resonator according to an embodiment of the present application;

[0044] Figure 7 is a plan view of a fifth film bulk acoustic resonator according to an embodiment of the present application;

[0045] Figure 8 is a plan view of a sixth film bulk acoustic resonator according to an embodiment of the present application;

[0046] Figure 9 is a flow chart of a preparation method of the first film bulk acoustic resonator according to an embodiment of the present application;

[0047] Figure 10 is a structural schematic diagram corresponding to the preparation method of the first film bulk acoustic resonator according to the embodiment of the present application;

[0048] Figure 11 is a flow chart of a preparation method of the second film bulk acoustic resonator according to an embodiment of the present application;

[0049] Figure 12 is a structure diagram corresponding to a second film bulk acoustic resonator preparation method according to an embodiment of the present application;

[0050] Figure 13 is a flow chart of a third film bulk acoustic resonator preparation method according to an embodiment of the present application;

[0051] Figure 14 is a structure diagram corresponding to a third film bulk acoustic resonator preparation method according to an embodiment of the present application. DETAILED DESCRIPTION

[0052] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the scope of protection of the present application.

[0053] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0054] Figure 1 is a cross-sectional view of a first film bulk acoustic resonator according to an embodiment of the present application, Figure 2 is a top view of a first film bulk acoustic resonator according to an embodiment of the present application. In combination with Figure 1 and Figure 2 as shown, the film bulk acoustic resonator comprises:

[0055] a substrate 1, a transducer stack structure 2, a temperature compensation layer 3 and a first protruding structure 4;

[0056] The transducer stack structure 2 is located on one side of the substrate 1;

[0057] The temperature compensation layer 3 and the first protruding structure 4 are located inside the transducer stack structure 2, and the first protruding structure 4 is located on the side of the temperature compensation layer 3 away from the substrate 1, for forming a first protrusion 40 on the surface of the transducer stack structure 2 away from the substrate 1; the temperature-elasticity coefficient of the temperature compensation layer 3 is greater than zero, and the temperature-elasticity coefficient of the transducer stack structure 2 is less than zero;

[0058] The transducer stack structure 2 comprises a working area; in the thickness direction y of the film bulk acoustic resonator, the projection of the temperature compensation layer 3 on the plane of the substrate 1 covers the projection of the working area on the plane of the substrate 1; the projection of the working area on the plane of the substrate 1 covers the projection of the first protruding structure 4 on the plane of the substrate 1, and the first protruding structure 4 is connected to the side surface of the temperature compensation layer 3.

[0059] The substrate 1 can be used as the base of the film bulk acoustic resonator, and a silicon material substrate 1 can be selected in the actual preparation process. The transducer stack structure 2 can comprise an electrode and a piezoelectric layer, which are arranged on one side of the substrate 1 and form a resonance by converting electrical energy into acoustic waves through the inverse piezoelectric effect. The working area of the transducer stack structure 2 can be the overlapping area of the electrode and the piezoelectric layer, which is the main resonance area. The working area is the area where electrical energy is converted into acoustic waves and generates oscillation. In some embodiments, a cavity 10 is arranged in the substrate 1, which can enhance the reflection performance of the acoustic waves.

[0060] The temperature compensation layer 3 can be made of a material with a positive temperature coefficient. For example, SiO2, F-doped SiO2, B-doped SiO2, etc. The temperature-elastic coefficient can be used to characterize the change of Young's modulus affected by temperature. The temperature-elastic coefficient of the temperature compensation layer 3 is a positive temperature-elastic coefficient, while the temperature-elastic coefficient in the transducer stack structure 2 is a negative temperature-elastic coefficient. By arranging the temperature compensation layer 3 in the transducer stack structure 2, the temperature compensation layer 3 can compensate for the negative temperature-elastic coefficient of the transducer stack structure 2 through its own elastic change, thereby reducing the influence of temperature on the performance of the film bulk acoustic resonator.

[0061] The first protruding structure 4 is arranged on the side of the temperature compensation layer 3 away from the substrate 1, which can be obtained by etching the temperature compensation layer 3 or continuing to grow on the side of the temperature compensation layer 3. The technical solution of the embodiment of the present application continues to stack other film layers after preparing the first protruding structure 4 on the temperature compensation layer 3. Since the thickness of the prepared film layer is fixed, the first protrusion 40 is formed on the surface of the film bulk acoustic resonator. The first protrusion 40 can avoid unnecessary vibration or damping when the working area of the transducer stack structure 2 works, and reduce the energy loss caused by other non-resonance.

[0062] Specifically, the thickness direction of the film bulk acoustic resonator is set as the y direction, in order to ensure the effect of reducing temperature drift of the temperature compensation layer 3, the projection of the temperature compensation layer 3 on the plane of the substrate 1 covers the projection of the working area on the plane of the substrate 1, and then the negative temperature-elastic coefficient in the film bulk acoustic resonator is better compensated. At the same time, in order to avoid unnecessary vibration or damping, the projection of the working area on the plane of the substrate 1 covers the projection of the first protruding structure 4 on the plane of the substrate 1, and then the uneven surface of the transducer stack structure 2 caused by the first protruding structure 4 forms the first protrusion 40, so as to reduce the energy loss caused by other non-resonance. The first protruding structure 4 is connected with the side surface of the temperature compensation layer 3, so that the first protruding structure 4 is aligned with the temperature compensation layer 3 along the thickness direction y of the film bulk acoustic resonator, ensuring the normal work of the working area and achieving the purpose of reducing energy loss.

[0063] It can be understood that the purpose of the first protruding structure 4 in the embodiment of the present application is to make the film layer arranged on the first protruding structure 4 also have the first protrusion 40, so that the electrode surface of the transducer stack structure 2 is protruded, the first protrusion 40 area is in the working area, and then the protruding structure can avoid unnecessary vibration or damping during work, and reduce the energy loss caused by other non-resonance, so as to reduce the frequency temperature drift of the film bulk acoustic resonator while improving the Q value of the film bulk acoustic resonator.

[0064] Exemplarily, the temperature compensation layer 3 is arranged in the piezoelectric layer of the transducer stack structure 2, and the specific preparation method is as follows: first, a bottom electrode layer in the transducer stack structure 2 is prepared on one side of the substrate 1, a piezoelectric layer with a certain thickness is deposited on the basis of the bottom electrode layer, the temperature compensation layer 3 is deposited on the basis of the piezoelectric layer, the first protruding structure 4 is prepared at the corresponding position after the preparation of the temperature compensation layer 3, and the first protruding structure 4 is aligned with the temperature compensation layer 3 along the thickness direction y of the film bulk acoustic resonator. After the first protruding structure 4 is prepared, the piezoelectric layer is regrown to cover the temperature compensation layer 3 and the first protruding structure 4, and the first protrusion 40 exists on the surface of the piezoelectric layer at the corresponding position of the first protruding structure 4, and then after the top electrode layer is prepared, the first protrusion 40 also exists at the corresponding position of the top electrode layer, so as to achieve the purpose of reducing energy leakage.

[0065] It can be understood that the embodiment of the present application forms the first protruding structure 4 at the same time of preparing the temperature compensation layer 3, without forming the first protrusion 40 by other processes when preparing the transducer stack structure 2, and the film layer deposited subsequently naturally forms the first protrusion 40 after the temperature compensation layer 3 forms the first protruding structure 4, which not only ensures the arrangement of the temperature compensation layer 3 but also avoids unnecessary vibration or damping, so as to reduce the frequency temperature drift of the film bulk acoustic resonator while improving the Q value of the film bulk acoustic resonator.

[0066] The technical scheme of the embodiment of the present application sets the temperature compensation layer in the film bulk acoustic resonator, sets the first protruding structure on the temperature compensation layer, and forms the corresponding first protrusion on the top of the film bulk acoustic resonator through the subsequent deposition of the stacked film, so that unnecessary vibration or damping can be avoided, the energy loss caused by other non-resonance is reduced, the frequency temperature drift of the film bulk acoustic resonator is reduced, and the Q value of the film bulk acoustic resonator is improved.

[0067] Optionally, continuing to refer to Figure 1 and Figure 2 As shown in the drawings, along the thickness direction y of the film bulk acoustic resonator, the projection of the first protruding structure 4 on the plane of the substrate 1 is a closed figure.

[0068] The first protruding structure 4 is a closed figure, and the specific shape of the closed figure can be determined according to the projection shape of the working area on the substrate 1.

[0069] For example, along the thickness direction y of the film bulk acoustic resonator, the projection of the working area on the surface of the substrate 1 is shown in the drawings. Since the first protruding structure 4 needs to be aligned with the temperature compensation layer 3 along the y direction, the first protruding structure 4 can also be set as a closed figure. The closed figure is the same as the figure of the working area but has a different size. The projection of the working area along the y direction covers the closed figure, and the closed figure coincides with the edge of the projection of the working area along the y direction, so that the purpose of reducing the non-resonance energy loss is achieved.

[0070] In some embodiments, the width of the first protruding structure 4 is less than 10 μm, which ensures that the sound wave can be effectively transmitted in the working area while reducing the energy leakage of the sound wave.

[0071] The technical scheme of the embodiment of the present application sets the first protruding structure in the projection of the substrate on the plane as a closed figure, so that a closed protruding structure is formed on the surface of the film bulk acoustic resonator, which can further reduce the energy loss caused by non-resonance and improve the performance of the film bulk acoustic resonator.

[0072] Optionally, Figure 3 is a cross-sectional view of a second film bulk acoustic resonator according to an embodiment of the present application, Figure 4 is a plan view of the second film bulk acoustic resonator according to the embodiment of the present application, in combination with Figure 3 and Figure 4 Further includes a second protruding structure 5;

[0073] The second protruding structure 5 is located on the side of the temperature compensation layer 3 away from the substrate 1 and is spaced apart from the first protruding structure 4, and is used to form a second protrusion 50 on the surface of the transducer stack structure 2 away from the substrate 1;

[0074] The projection of the working area on the plane of the substrate 1 covers the projection of the second protruding structure 5 on the plane of the substrate 1 along the thickness direction y of the film bulk acoustic resonator, and the projection of the second protruding structure 5 on the plane of the substrate 1 is parallel to the projection of the first protruding structure 4 on the plane of the substrate 1.

[0075] The first protruding structure 4 and the second protruding structure 5 can be arranged on the same side of the temperature compensation layer 3, and the first protruding structure 4 and the second protruding structure 5 can be simultaneously prepared, and the first protruding structure 4 is arranged at a distance from the second protruding structure 5, so that the first protrusion 40 and the second protrusion 50 are formed on the surface of the transducer stack structure 2 when the transducer stack structure 2 is subsequently prepared, and the purpose of inhibiting the leakage of acoustic wave energy is further achieved.

[0076] Specifically, the projection of the working area on the plane of the substrate 1 covers the projection of the second protruding structure 5 on the plane of the substrate 1 along the thickness direction y of the film bulk acoustic resonator, so that the second protrusion 50 formed by the second protruding structure 5 is in the working area, and the effect of inhibiting the leakage of acoustic wave energy is ensured. At the same time, the projection of the second protruding structure 5 on the plane of the substrate 1 is parallel to the projection of the first protruding structure 4 on the plane of the substrate 1, so that the projections of the working area, the first protruding structure 4 and the second protruding structure 5 on the surface of the substrate 1 are nested with each other, the distance between the first protruding structure 4 and the second protruding structure 5 is fixed and consistent, the propagation effect of the acoustic wave in the working area is ensured, and the performance of the film bulk acoustic resonator is improved.

[0077] It can be understood that the second protruding structure 5 can be determined according to the Q value requirement and the K value requirement of the film bulk acoustic resonator. The width of the first protruding structure 4 and the width of the second protruding structure 5 can be the same or different, and the thickness along the y direction can be the same or different, and can also be set according to requirements.

[0078] The technical scheme of the embodiment of the present application can set the second protruding structure on the basis of the first protruding structure, change the distribution of the protrusions on the working area, and further ensure the propagation effect of the acoustic wave in the working area while improving the performance of the film bulk acoustic resonator.

[0079] Optionally, Figure 5 A third film bulk acoustic resonator is provided according to the embodiment of the present application, and a plan view of the third film bulk acoustic resonator is shown in FIG. 4. Figure 5 As shown in FIG. 4, the second protruding structure 5 includes at least two second protruding structures 5.

[0080] The distance between each second protruding structure 5 and the first protruding structure 4 is the same.

[0081] A plurality of second protruding structures 5 can be arranged, each second protruding structure 5 is parallel to the first protruding structure 4, and the distance between each second protruding structure 5 and the first protruding structure 4 is the same.

[0082] As shown in the figure, the second protruding structures 5 are periodically and spacedly arranged, each of the second protruding structures 5 is parallel to part of the first protruding structures 4 to ensure that the distance between the single second protruding structure 5 and the first protruding structure 4 is the same and the interval distance between each second protruding structure 5 and the first protruding structure 4 is the same, and this way can also achieve the purpose of inhibiting the sound wave energy leakage. Figure 5

[0083] The technical scheme of the embodiment of the present application can set multiple second protruding structures on the basis of the first protruding structure, change the distribution of the protrusions on the working area, and improve the performance of the film bulk acoustic resonator.

[0084] Optionally, Figure 6 The fourth film bulk acoustic resonator provided by the embodiment of the present application is shown in the figure, which also comprises a third protruding structure 7. Figure 6

[0085] The third protruding structure 7 is located on the side of the temperature compensation layer 3 away from the substrate 1 and is arranged between the first protruding structure 4 and the second protruding structure 5, and is used to form a third protrusion 70 on the surface of the transducer stack structure 2 away from the substrate 1.

[0086] In the thickness direction y of the film bulk acoustic resonator, the projection of the working area on the plane of the substrate 1 covers the projection of the third protruding structure 7 on the plane of the substrate 1.

[0087] The first protruding structure 4, the second protruding structure 5 and the third protruding structure 7 can be arranged on the same side of the temperature compensation layer 3 and are simultaneously prepared, and the first protruding structure 4, the second protruding structure 5 and the third protruding structure 7 are spacedly arranged, so that when the transducer stack structure 2 is subsequently prepared, the first protrusion 40, the second protrusion 50 and the third protrusion 70 are formed on the surface of the transducer stack structure 2, and further achieve the purpose of inhibiting the sound wave energy leakage.

[0088] Specifically, on the basis of the first protruding structure 4 ensuring the sound wave energy leakage, the arrangement mode of the third protruding structure 7 can be determined according to requirements, for example, as shown in the figure, the first protruding structure 4 and the second protruding structure 5 are both closed figures with the same shape, the third protruding structure 7 is multiple and is periodically arranged between the first protruding structure 4 and the second protruding structure 5, and each of the third protruding structures 7 is parallel to the first protruding structure 4 and the second protruding structure 5. Figure 6 Figure 7 The fifth film bulk acoustic resonator provided by the embodiment of the present application is shown in the figure, which also comprises a third protruding structure 7. Figure 7 ​​​As shown, the first protruding structure 4 is a closed figure with the same shape, the second protruding structure 5 includes a plurality of and is periodically arranged in parallel with part of the first protruding structure 4, the third protruding structure 7 also includes a plurality of and is periodically arranged in parallel with part of the first protruding structure 4, and the second protruding structure 5 and the third protruding structure 7 are not parallel. Figure 8 is a plan view of a sixth film bulk acoustic resonator according to an embodiment of the present application, as shown in the figure, Figure 8 As shown, the first protruding structure 4 and the second protruding structure 5 are both closed figures with the same shape, and the third protruding structure 7 is a cylinder and is periodically arranged between the first protruding structure 4 and the second protruding structure 5.

[0089] The technical scheme of the embodiment of the present application can set the third protruding structure on the basis of the first protruding structure and the second protruding structure, change the distribution of protrusions on the working area, and then change the suppression effect of acoustic wave leakage, thereby improving the performance of the film bulk acoustic resonator.

[0090] Optionally, continuing to refer to Figure 1 As shown, the transducer stack structure 2 includes a bottom electrode layer 21, a piezoelectric layer 22, and a top electrode layer 23 arranged in layers;

[0091] The temperature compensation layer 3 is arranged in the piezoelectric layer 22.

[0092] The piezoelectric layer 22 is located between the bottom electrode layer 21 and the top electrode layer 23, and the top electrode layer 23 is located on the side of the piezoelectric layer 22 away from the substrate 1. The working area of the transducer stack structure 2 is the overlapping area of the bottom electrode layer 21, the piezoelectric layer 22, and the top electrode layer 23, that is, the main resonance area.

[0093] The temperature compensation layer 3 is arranged in the piezoelectric layer 22, so that the piezoelectric layer 22 needs to be grown first when the temperature compensation layer 3 is prepared, and then the temperature compensation layer 3 and the first protruding structure 4 are prepared, and after the preparation is completed, the piezoelectric layer 22 is covered, so as to achieve the purpose of arranging the temperature compensation layer 3 in the piezoelectric layer 22. The first protruding structure 4 makes the surface of the piezoelectric layer 22 form a protrusion and form a first protrusion 40 on the surface of the top electrode layer 23 after the top electrode layer 23 is prepared, so as to achieve the purpose of suppressing acoustic wave leakage.

[0094] In some embodiments, the temperature compensation layer 3 can be arranged in the bottom electrode layer 21 or arranged in the top electrode layer 23, and only a protrusion is formed on the surface of the transducer stack structure 2.

[0095] The technical scheme of the embodiment of the present application is that the temperature compensation layer is arranged in the piezoelectric layer, so that a protrusion can be formed on the surface of the film bulk acoustic resonator in the subsequent film layer deposition process, unnecessary vibration or damping can be avoided, and energy loss caused by other non-resonance can be reduced, so that the frequency temperature drift of the film bulk acoustic resonator is reduced and the Q value of the film bulk acoustic resonator is improved.

[0096] Based on the same inventive concept, Figure 9 is a flow chart of a first film bulk acoustic resonator preparation method according to an embodiment of the present application, Figure 10 is a corresponding structural schematic diagram of the first film bulk acoustic resonator preparation method according to an embodiment of the present application, in combination with Figure 9 and Figure 10 The present application provides a film bulk acoustic resonator preparation method, which is used for preparing a film bulk acoustic resonator; the preparation method comprises the following steps:

[0097] S10, providing a substrate. As shown in step (a) of Figure 10 .

[0098] The substrate 1 can be used as the base of the film bulk acoustic resonator, and a silicon material substrate 1 can be selected in the actual preparation process.

[0099] S11, preparing a transducer stack structure, a temperature compensation layer and a first protrusion structure on one side of the substrate. As shown in step (b) of Figure 10 . The temperature compensation layer 3 and the first protrusion structure 4 are located inside the transducer stack structure 2, and the first protrusion structure 4 is located on the side of the temperature compensation layer 3 away from the substrate 1; the temperature-elasticity coefficient of the temperature compensation layer 3 is greater than zero, and the temperature-elasticity coefficient of the transducer stack structure 2 is less than zero.

[0100] The transducer stack structure 2 comprises a working area; along the thickness direction y of the film bulk acoustic resonator, the projection of the temperature compensation layer 3 on the plane of the substrate 1 covers the projection of the working area on the plane of the substrate 1; the projection of the working area on the plane of the substrate 1 covers the projection of the first protrusion structure 4 on the plane of the substrate 1, and the first protrusion structure 4 is connected with the side surface of the temperature compensation layer 3.

[0101] The temperature compensation layer 3 can be prepared from a material with a positive temperature-elasticity coefficient, for example, SiO2, F-doped SiO2, B-doped SiO2, etc. The temperature-elasticity coefficient of the temperature compensation layer 3 is a positive temperature-elasticity coefficient, while the temperature-elasticity coefficient in the transducer stack structure 2 is a negative temperature-elasticity coefficient, so that the influence of temperature on the performance of the film bulk acoustic resonator can be reduced.

[0102] The first protruding structure 4 is arranged on the side of the temperature compensation layer 3 away from the substrate 1, and can be obtained by etching the temperature compensation layer 3 or obtained by continuing to grow on the side of the temperature compensation layer 3. After the first protruding structure 4 is prepared on the temperature compensation layer 3, other film layers are continued to be stacked, and since the thickness of the prepared film layer is fixed, the first protrusion 40 is formed on the surface of the film bulk acoustic resonator. When the working area of the transducer stack structure 2 works, the first protrusion 40 can avoid unnecessary vibration or damping, and reduce the energy loss caused by other non-resonance.

[0103] For example, the substrate 1 is provided, and a cavity 10 is etched on one side of the substrate 1; a seed layer 11 is deposited on one side of the substrate 1; a bottom electrode layer 21 is prepared on one side of the seed layer 11, a piezoelectric layer 22 with a certain thickness is deposited on the basis of the bottom electrode layer 21, a temperature compensation layer 3 is deposited on the basis of the piezoelectric layer 22, and a first protruding structure 4 is prepared at the corresponding position after the temperature compensation layer 3 is prepared; after the first protruding structure 4 is prepared, the piezoelectric layer 22 is continued to be deposited to cover the temperature compensation layer 3 and the first protruding structure 4, and the surface of the piezoelectric layer 22 at the corresponding position of the first protruding structure 4 exists a first protrusion 40, and a top electrode layer 23 is continued to be deposited, and the top electrode layer 23 also exists a first protrusion 40 at the corresponding position, and the preparation of the film bulk acoustic resonator is completed.

[0104] The technical scheme of the embodiment of the present application is that the temperature compensation layer is prepared in the film bulk acoustic resonator, and the first protruding structure is prepared at the same time, and through the deposition of the subsequent stacked layer film, the corresponding first protrusion can be formed on the top of the film bulk acoustic resonator, unnecessary vibration or damping can be avoided, and the energy loss caused by other non-resonance can be reduced, so that the frequency temperature drift of the film bulk acoustic resonator is reduced, and the Q value of the film bulk acoustic resonator is improved.

[0105] On the basis of the above-mentioned embodiment, Figure 11 is a second film bulk acoustic resonator preparation method flow chart provided by the embodiment of the present application, Figure 12 is a second film bulk acoustic resonator preparation method corresponding structure schematic diagram provided by the embodiment of the present application, combined with Figure 11 and Figure 12 It is shown that the preparation method comprises:

[0106] S20, providing a substrate. As Figure 12 (c) step shown.

[0107] S21, preparing a transducer stack structure, a temperature compensation layer, a first protruding structure and a second protruding structure on one side of the substrate. As Figure 12 (d) step shown. Wherein, the second protruding structure 5 is arranged on the side of the temperature compensation layer 3 away from the substrate 1 and spaced apart from the first protruding structure 4;

[0108] The working area in the projection of the substrate 1 plane covers the projection of the second protruding structure 5 in the substrate 1 plane along the thickness direction y of the film bulk acoustic resonator; and the projection of the second protruding structure 5 in the substrate 1 plane is parallel to the projection of the first protruding structure 4 in the substrate 1 plane.

[0109] The first protruding structure 4 and the second protruding structure 5 can be arranged on the same side of the temperature compensation layer 3, and the first protruding structure 4 and the second protruding structure 5 can be simultaneously prepared; the first protruding structure 4 and the second protruding structure 5 are arranged at intervals, so that the first protrusion 40 and the second protrusion 50 are formed on the surface of the transducer stack structure 2 when the transducer stack structure 2 is subsequently prepared, and the purpose of inhibiting the leakage of acoustic wave energy is further achieved.

[0110] The technical scheme of the embodiment of the present application can simultaneously prepare the first protruding structure and the second protruding structure, change the distribution of the protrusions on the working area, and further ensure the propagation effect of the acoustic wave in the working area and improve the performance of the film bulk acoustic resonator.

[0111] On the basis of the above embodiment, Figure 13 is a third film bulk acoustic resonator preparation method flowchart provided by the embodiment of the present application, Figure 14 is a third film bulk acoustic resonator preparation method corresponding structure diagram provided by the embodiment of the present application, which is combined with Figure 13 and Figure 14 It is shown that the preparation method comprises:

[0112] S30, providing a substrate. As shown in step (e) of Figure 14 .

[0113] S31, growing a bottom electrode layer on one side of the substrate. As shown in step (f) of Figure 14 .

[0114] S32, growing a piezoelectric layer on the side of the bottom electrode layer away from the substrate. As shown in step (g) of Figure 14 .

[0115] Since the temperature compensation layer 3 and the first protruding structure 4 need to be arranged on the piezoelectric layer 22, the piezoelectric layer 22 needs to be prepared in two steps, and the piezoelectric layer 22 is prepared in S32 so as to grow the temperature compensation layer 3.

[0116] S33, growing a temperature compensation layer on the side of the piezoelectric layer away from the bottom electrode layer. As shown in step (h) of Figure 14 .

[0117] S34, preparing a first protruding structure on the side of the temperature compensation layer away from the piezoelectric layer. As shown in step (i) of Figure 14 .

[0118] The first protruding structure 4 and the temperature compensation layer 3 can be made of the same material or different materials. When made of the same material, the first protruding structure 4 can be formed by etching the temperature compensation layer 3, or can be formed by depositing twice and patterning etching. When made of different materials, the first protruding structure 4 can be deposited after the temperature compensation layer 3 is deposited.

[0119] S35, growing the piezoelectric layer and the top electrode layer again on the side of the first protruding structure away from the piezoelectric layer. As shown in Figure 14 (j) of the specific embodiment.

[0120] The piezoelectric layer 22 and the top electrode layer 23 are grown again on the side of the first protruding structure 4 away from the piezoelectric layer 22, so that the first protrusion 40 is formed on the surface of the piezoelectric layer 22 and the top electrode layer 23, to suppress the energy loss caused by non-resonance.

[0121] The technical solution of the embodiment of the present application sets the temperature compensation layer in the piezoelectric layer, so that a protrusion can be formed on the surface of the film bulk acoustic resonator in the subsequent film layer deposition process, unnecessary vibration or damping can be avoided, and the energy loss caused by other non-resonance can be reduced, so that the frequency temperature drift of the film bulk acoustic resonator is reduced and the Q value of the film bulk acoustic resonator is improved.

[0122] It should be understood that the various forms of flow shown above can be used to reorder, add or delete steps. For example, each step described in the present application can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solution of the present application can be achieved, which is not limited herein.

[0123] The above specific embodiments do not constitute a limitation on the protection scope of the present application. 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 modification, equivalent replacement and improvement within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A film bulk acoustic resonator, characterized by, The film bulk acoustic resonator comprises: a substrate, a transducer stack structure, a temperature compensation layer and a first protruding structure; the transducer stack structure is located on one side of the substrate; the temperature compensation layer and the first protruding structure are located inside the transducer stack structure, and the first protruding structure is located on the side of the temperature compensation layer away from the substrate, for forming a first protrusion on the surface of the transducer stack structure away from the substrate; the temperature-elasticity coefficient of the temperature compensation layer is greater than zero, and the temperature-elasticity coefficient of the transducer stack structure is less than zero; the transducer stack structure comprises a working area; along the thickness direction of the film bulk acoustic resonator, the projection of the temperature compensation layer on the plane of the substrate covers the projection of the working area on the plane of the substrate; the projection of the working area on the plane of the substrate covers the projection of the first protruding structure on the plane of the substrate, and the side of the first protruding structure is connected with the temperature compensation layer.

2. The film bulk acoustic resonator of claim 1, wherein, Along the thickness direction of the film bulk acoustic resonator, the projection of the first protruding structure on the plane of the substrate is a closed figure.

3. The film bulk acoustic resonator of claim 1, wherein, Further comprising a second protruding structure; the second protruding structure is located on the side of the temperature compensation layer away from the substrate and is arranged in a spaced manner with the first protruding structure, for forming a second protrusion on the surface of the transducer stack structure away from the substrate; along the thickness direction of the film bulk acoustic resonator, the projection of the working area on the plane of the substrate covers the projection of the second protruding structure on the plane of the substrate; the projection of the second protruding structure on the plane of the substrate is parallel to the projection of the first protruding structure on the plane of the substrate.

4. The film bulk acoustic resonator of claim 3, wherein, The second protruding structure comprises at least two; each of the second protruding structures has the same spacing distance with the first protruding structure.

5. The film bulk acoustic resonator of claim 3, wherein, Further comprising a third protruding structure; the third protruding structure is located on the side of the temperature compensation layer away from the substrate and is arranged between the first protruding structure and the second protruding structure, for forming a third protrusion on the surface of the transducer stack structure away from the substrate; along the thickness direction of the film bulk acoustic resonator, the projection of the working area on the plane of the substrate covers the projection of the third protruding structure on the plane of the substrate.

6. The film bulk acoustic resonator of claim 1, wherein, The width of the first protruding structure is less than 10 μm.

7. The film bulk acoustic resonator of claim 1, wherein, The transducer stack structure comprises a bottom electrode layer, a piezoelectric layer and a top electrode layer arranged in a stack; the temperature compensation layer is arranged in the piezoelectric layer.

8. A method of fabricating a film bulk acoustic resonator, characterized by, The method for preparing the film bulk acoustic resonator of any one of claims 1-7 comprises: providing a substrate; preparing a transducer stack structure, a temperature compensation layer and a first protruding structure on one side of the substrate; wherein the temperature compensation layer and the first protruding structure are located inside the transducer stack structure, and the first protruding structure is located on the side of the temperature compensation layer away from the substrate; the temperature-elasticity coefficient of the temperature compensation layer is greater than zero, and the temperature-elasticity coefficient of the transducer stack structure is less than zero; The transducer stack structure comprises a working area; in a thickness direction of the film bulk acoustic resonator, a projection of the temperature compensation layer on a plane where the substrate is located covers a projection of the working area on the plane where the substrate is located; the projection of the working area on the plane where the substrate is located covers a projection of the first protruding structure on the plane where the substrate is located and the first protruding structure is connected with a side surface of the temperature compensation layer.

9. The production method according to claim 8, characterized by, The transducer stack structure, the temperature compensation layer and the first protruding structure are prepared on one side of the substrate, comprising: The transducer stack structure, the temperature compensation layer, the first protruding structure and the second protruding structure are prepared on one side of the substrate; wherein the second protruding structure is located on a side of the temperature compensation layer away from the substrate and is arranged in a spaced manner with the first protruding structure; In the thickness direction of the film bulk acoustic resonator, the projection of the working area on the plane where the substrate is located covers the projection of the second protruding structure on the plane where the substrate is located; the projection of the second protruding structure on the plane where the substrate is located is parallel to the projection of the first protruding structure on the plane where the substrate is located.

10. The preparation method according to claim 8, characterized in that, The transducer stack structure, the temperature compensation layer and the first protruding structure are prepared on one side of the substrate, comprising: A bottom electrode layer is grown on one side of the substrate; A piezoelectric layer is grown on a side of the bottom electrode layer away from the substrate; A temperature compensation layer is grown on a side of the piezoelectric layer away from the bottom electrode layer; A first protruding structure is prepared on a side of the temperature compensation layer away from the piezoelectric layer; The piezoelectric layer and a top electrode layer are grown again on a side of the first protruding structure away from the piezoelectric layer.

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