Film bulk acoustic resonator and preparation method thereof

Abstract

The invention discloses a film bulk acoustic resonator and a preparation method thereof. The film bulk acoustic resonator comprises a substrate, a transducer stacking structure, a temperature compensation layer and a first bulge structure, the transducer stacking structure is positioned on one side of the substrate; the temperature compensation layer and the first protruding structure are located in the transducer stacking structure, and the first protruding structure is located on the side, away from the substrate, of the temperature compensation layer. The transducer stacking 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 where the substrate is located covers the 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 the projection of the first protruding structure on the plane where the substrate is located, and the first protruding structure is connected with the side face of the temperature compensation layer. According to the technical scheme, the Q value of the film bulk acoustic resonator is improved while the frequency temperature drift of the film bulk acoustic resonator is reduced.

Description

Technical Field

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

[0002] With the ultra-high-speed development of wireless communication technology and the multi-functionalization of communication terminals, higher performance requirements are put forward for 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 wave 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 characteristics, steep filter skirts and extremely high Q values, operating frequencies, sensitivities, resolutions, and power capacity that can be tolerated. Therefore, thin film bulk acoustic wave resonators occupy most of the application fields of wireless communication.

[0003] As the operating temperature changes, the resonance frequency of the thin film bulk acoustic wave resonator will shift. Due to the large number of frequency bands in modern communication systems and the small interval between adjacent channels, the frequency drift caused by temperature may affect the signal transmission of adjacent frequency bands, thus causing signal interference. Therefore, ensuring that the thin film bulk acoustic wave resonator has excellent temperature stability is crucial for avoiding communication interference.

[0004] The existing methods for reducing the frequency drift of thin film bulk acoustic wave resonators mainly involve adding temperature compensation materials to the structure of the thin film bulk acoustic wave resonator. Usually, a whole layer of temperature compensation material is added to the thin film bulk acoustic wave resonator, but the existing technical means will cause a significant decline in the performance of the thin film bulk acoustic wave resonator, easily generate parasitic modes, and seriously affect signal transmission. Summary of the Invention

[0005] The present invention provides a thin film bulk acoustic wave resonator and a preparation method thereof to solve the problems of performance decline and generation of parasitic modes caused by introducing temperature compensation materials into the thin film bulk acoustic wave resonator in the prior art.

[0006] According to one aspect of the present invention, a thin film bulk acoustic wave resonator is provided, including: a substrate, a transducer stack structure, a temperature compensation layer, and a first protrusion structure;

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

[0008] The temperature compensation layer and the first protrusion structure are located inside the transducer stack structure, and the first protrusion 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 side; the temperature-elastic coefficient of the temperature compensation layer is greater than zero, and the temperature-elastic coefficient of the transducer stack structure is less than zero;

[0009] The transducer stack structure includes a working area; in the thickness direction of the thin film bulk acoustic wave 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 convex structure on the plane of the substrate and the side surface of the first convex structure is connected to the temperature compensation layer.

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

[0011] Optionally, it further includes a second convex structure;

[0012] The second convex structure is located on the side of the temperature compensation layer away from the substrate and is spaced from the first convex structure, and is used to form a second convex on the surface of the transducer stack structure away from the substrate side;

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

[0014] Optionally, the second convex structure includes at least two;

[0015] The spacing distance between each second convex structure and the first convex structure is the same.

[0016] Optionally, it further includes a third convex structure;

[0017] The third convex structure is located on the side of the temperature compensation layer away from the substrate and is arranged between the first convex structure and the second convex structure, and is used to form a third convex on the surface of the transducer stack structure away from the substrate side;

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

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

[0020] Optionally, the transducer stack structure includes a bottom electrode layer, a piezoelectric layer and a top electrode layer which are stacked;

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

[0022] According to another aspect of the present invention, a preparation method of a thin film bulk acoustic wave resonator is provided, which is used to prepare a thin film bulk acoustic wave resonator; the preparation method includes:

[0023] Providing a substrate;

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

[0025] The transducer stack structure includes a working area; along the thickness direction of the thin film bulk acoustic wave 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 protrusion structure on the plane of the substrate, and the first protrusion structure is connected to the side surface of the temperature compensation layer.

[0026] Optionally, preparing a transducer stack structure, a temperature compensation layer, and a first protrusion structure on one side of a substrate includes:

[0027] A transducer stack structure, a temperature compensation layer, a first protrusion structure, and a second protrusion structure are prepared on one side of the substrate; wherein, the second protrusion structure is located on the side of the temperature compensation layer away from the substrate and is spaced from the first protrusion structure;

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

[0029] Optionally, preparing a transducer stack structure, a temperature compensation layer, and a first protrusion structure on one side of a substrate includes:

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

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

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

[0033] Preparing a first protrusion structure on the side of the temperature compensation layer away from the piezoelectric layer;

[0034] Growing a piezoelectric layer and a top electrode layer again on the side of the first protrusion structure away from the piezoelectric layer.

[0035] The technical solution of the present invention, by setting a temperature compensation layer in the thin film bulk acoustic wave resonator and setting a first protrusion structure on the temperature compensation layer, through the deposition of subsequent stacked layer films, a corresponding first protrusion can be formed on the top of the thin film bulk acoustic wave resonator, which can avoid unnecessary vibration or damping, reduce the energy loss caused by other non-resonances, and improve the Q value of the thin film bulk acoustic wave resonator while reducing the frequency temperature drift of the thin film bulk acoustic wave resonator.

[0036] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become readily apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces 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.

[0038] Figure 1 is a cross-sectional view of the first thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0039] Figure 2 is a top view of the first thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0040] Figure 3 is a cross-sectional view of the second thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0041] Figure 4 is a top view of the second thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0042] Figure 5 is a top view of the third thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0043] Figure 6 is a top view of the fourth thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0044] Figure 7 is a top view of the fifth thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0045] Figure 8 is a top view of the sixth thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0046] Figure 9 is a flowchart of the preparation method of the first thin film bulk acoustic resonator provided according to an embodiment of the present invention;

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

[0048] Figure 11 is a flowchart of the preparation method of the second thin film bulk acoustic resonator provided according to an embodiment of the present invention;

[0049] Figure 12 It is a schematic structural diagram corresponding to the second method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present invention;

[0050] Figure 13 It is a flowchart of the third method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present invention;

[0051] Figure 14 It is a schematic structural diagram corresponding to the third method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present invention. Detailed implementation manners

[0052] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. 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.

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

[0054] Figure 1 It is a cross-sectional view of the first thin film bulk acoustic resonator according to an embodiment of the present invention, Figure 2 It is a top view of the first thin film bulk acoustic resonator according to an embodiment of the present invention. Combining Figure 1 and Figure 2 as shown, the thin film bulk acoustic resonator includes:

[0055] a substrate 1, a transducer stack structure 2, a temperature compensation layer 3, and a first protrusion 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 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, for forming a first protrusion 40 on the surface of the transducer stack structure 2 away from the substrate 1; the temperature-elastic coefficient of the temperature compensation layer 3 is greater than zero, and the temperature-elastic coefficient of the transducer stack structure 2 is less than zero;

[0058] The transducer stack structure 2 includes a working area; along the thickness direction y of the thin-film bulk acoustic wave resonator, the projection of the temperature compensation layer 3 on the plane where the substrate 1 is located covers the projection of the working area on the plane where the substrate 1 is located; the projection of the working area on the plane where the substrate 1 is located covers the projection of the first convex structure 4 on the plane where the substrate 1 is located, and the first convex structure 4 is connected to the side surface of the temperature compensation layer 3.

[0059] Among them, the substrate 1 can be used as the base of the thin-film bulk acoustic wave resonator, and a silicon material substrate 1 can be selected during actual preparation. The transducer stack structure 2 may include an electrode and a piezoelectric layer, which are arranged on one side of the substrate 1 and convert electrical energy into acoustic waves through the inverse piezoelectric effect to form resonance. 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. This working area is the area where electrical energy is converted into acoustic waves and oscillations are generated. In some embodiments, a cavity 10 is provided in the substrate 1, which can enhance the reflection performance of the acoustic waves.

[0060] Among them, the temperature compensation layer 3 can be made of a material with a positive temperature coefficient. For example, SiO 2 , F-doped SiO 2 , B-doped SiO 2 etc. The temperature-elastic coefficient can be used to characterize the change in 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 setting 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 thin-film bulk acoustic wave resonator.

[0061] Among them, the first convex 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 by continuing to grow on one side of the temperature compensation layer 3. In the technical solution of the embodiment of the present invention, after the first convex structure 4 is prepared on the temperature compensation layer 3, other film layers are stacked continuously. Since the thickness of the prepared film layer is fixed, a first convex 40 is formed on the surface of the thin-film bulk acoustic wave resonator. This first convex 40 can avoid unnecessary vibration or damping when the working area of the transducer stack structure 2 is working, and reduce the energy loss caused by other non-resonances.

[0062] Specifically, the thickness direction of the thin-film bulk acoustic resonator is set as the y direction. To ensure the effect of reducing the temperature drift of the temperature compensation layer 3, the projection of the temperature compensation layer 3 on the plane where the substrate 1 is located covers the projection of the working area on the plane where the substrate 1 is located, so as to better compensate the negative temperature-elastic coefficient in the thin-film bulk acoustic resonator. At the same time, to avoid unnecessary vibration or damping, the projection of the working area on the plane where the substrate 1 is located covers the projection of the first convex structure 4 on the plane where the substrate 1 is located, so that the unevenness of the surface of the transducer stack structure 2 caused by the first convex structure 4 forms the first convex 40, achieving the reduction of energy loss caused by other non-resonances. Among them, the first convex structure 4 is connected to the side surface of the temperature compensation layer 3, so that the first convex structure 4 is aligned with the temperature compensation layer 3 along the thickness direction y of the thin-film bulk acoustic resonator, ensuring the normal operation of the working area and achieving the purpose of reducing energy loss.

[0063] It can be understood that the purpose of setting the first convex structure 4 in the embodiment of the present invention is to make the film layer stacked on the first convex structure 4 also have the first convex 40, so that the electrode surface of the transducer stack structure 2 is convex. The first convex 40 area is within the working area, so that the convex structure can avoid unnecessary vibration or damping during operation, reducing energy loss caused by other non-resonances, thereby improving the Q value of the thin-film bulk acoustic resonator while reducing the frequency temperature drift of the thin-film bulk acoustic resonator.

[0064] Exemplarily, the temperature compensation layer 3 is disposed in the piezoelectric layer of the transducer stack structure 2. The specific preparation method is as follows: First, the 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. After the temperature compensation layer 3 is prepared, the first convex structure 4 is prepared at the corresponding position. Along the thickness direction y of the thin-film bulk acoustic resonator, the first convex structure 4 is aligned with the temperature compensation layer 3. After the first convex structure 4 is prepared, a piezoelectric layer is grown to cover the temperature compensation layer 3 and the first convex structure 4. There is a first convex 40 on the surface of the piezoelectric layer at the corresponding position of the first convex structure 4. Then, after the top electrode layer is prepared, there is also a first convex 40 at the corresponding position of the top electrode layer, achieving the purpose of reducing energy leakage.

[0065] It can be understood that in the embodiment of the present invention, the first convex structure 4 is formed while the temperature compensation layer 3 is prepared. There is no need to form the first convex 40 by other processes when preparing the transducer stack structure 2. After the first convex structure 4 is formed in the temperature compensation layer 3, the subsequently deposited film layer naturally forms the first convex 40, which not only ensures the setting of the temperature compensation layer 3 but also avoids unnecessary vibration or damping, improving the Q value of the thin-film bulk acoustic resonator while reducing the frequency temperature drift of the thin-film bulk acoustic resonator.

[0066] In the technical solution of the embodiment of the present invention, by providing a temperature compensation layer in the thin film bulk acoustic resonator and providing a first convex structure on the temperature compensation layer, through the subsequent deposition of the stacked layer thin film, a corresponding first convex can be formed on the top of the thin film bulk acoustic resonator, which can avoid unnecessary vibration or damping, reduce energy loss caused by other non-resonances, and improve the Q value of the thin film bulk acoustic resonator while reducing the frequency temperature drift of the thin film bulk acoustic resonator.

[0067] Optionally, continue to refer to Figure 1 and Figure 2 As shown, along the thickness direction y of the thin film bulk acoustic resonator, the projection of the first convex structure 4 on the plane where the substrate 1 is located is a closed figure.

[0068] Among them, the first convex 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] Exemplarily, along the thickness direction y of the thin film bulk acoustic resonator, the projection of the working area on the surface of the substrate 1 is as shown in the figure. Since it is necessary to set the alignment of the first convex structure 4 and the temperature compensation layer 3 in the y direction, the first convex structure 4 can also be set as a closed figure. The closed figure is the same as the figure of the working area but different in size. The projection of the working area in the y direction covers the closed figure and the edge of the closed figure coincides with the projection edge of the working area, achieving the purpose of reducing non-resonant energy loss.

[0070] In some embodiments, the width of the first convex structure 4 is less than 10 μm, which can reduce the leakage of acoustic wave energy while ensuring the effective transmission of acoustic waves in the working area.

[0071] In the technical solution of the embodiment of the present invention, by setting the projection of the first convex structure on the plane where the substrate is located as a closed figure, a closed convex structure is formed on the surface of the thin film bulk acoustic resonator, which can further reduce the energy loss caused by non-resonances and improve the performance of the thin film bulk acoustic resonator.

[0072] Optionally, Figure 3 is a cross-sectional view of the second thin film bulk acoustic resonator provided according to the embodiment of the present invention, Figure 4 is a top view of the second thin film bulk acoustic resonator provided according to the embodiment of the present invention. Combining Figure 3 and Figure 4 As shown, it further includes a second convex structure 5;

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

[0074] Along the thickness direction y of the thin film bulk acoustic wave resonator, the projection of the working area on the plane where the substrate 1 is located covers the projection of the second convex structure 5 on the plane where the substrate 1 is located; the projection of the second convex structure 5 on the plane where the substrate 1 is located is parallel to the projection of the first convex structure 4 on the plane where the substrate 1 is located.

[0075] Among them, the first convex structure 4 and the second convex structure 5 can be arranged on the same side of the temperature compensation layer 3, the first convex structure 4 and the second convex structure 5 can be formed simultaneously, and the first convex structure 4 and the second convex structure 5 are arranged at intervals, so that when the transducer stack structure 2 is prepared subsequently, the first convex 40 and the second convex 50 are formed on the surface of the transducer stack structure 2, further serving the purpose of suppressing the leakage of acoustic wave energy.

[0076] Specifically, along the thickness direction y of the thin film bulk acoustic wave resonator, the projection of the working area on the plane where the substrate 1 is located covers the projection of the second convex structure 5 on the plane where the substrate 1 is located, so that the second convex 50 formed by the second convex structure 5 is within the working area, ensuring the effect of suppressing the leakage of acoustic wave energy. At the same time, the projection of the second convex structure 5 on the plane where the substrate 1 is located is set to be parallel to the projection of the first convex structure 4 on the plane where the substrate 1 is located, so that the projections of the working area, the first convex structure 4, and the second convex structure 5 on the surface of the substrate 1 are nested with each other, and the interval distance between the first convex structure 4 and the second convex structure 5 is fixed and consistent, ensuring the propagation effect of acoustic waves in the working area and improving the performance of the thin film bulk acoustic wave resonator.

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

[0078] The technical solution of the embodiment of the present invention can set the second convex structure on the basis of the first convex structure, change the distribution of the convexes in the working area, and further improve the performance of the thin film bulk acoustic wave resonator while ensuring the propagation effect of acoustic waves in the working area.

[0079] Optionally, Figure 5 is a top view of the third thin film bulk acoustic wave resonator provided by the embodiment of the present invention. As Figure 5 shown, the second convex structure 5 includes at least two;

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

[0081] Among them, a plurality of second convex structures 5 can be set, each second convex structure 5 is partially parallel to the first convex structure 4, and the interval distance between each second convex structure 5 and the first convex structure 4 is the same.

[0082] Exemplarily, as Figure 5 shown, the second protrusion structures 5 are arranged at periodic intervals. Each second protrusion structure 5 is parallel to a part of the first protrusion structure 4 to ensure that the distance between a single second protrusion structure 5 and the first protrusion structure 4 is the same, and the interval distance between each second protrusion structure 5 and the first protrusion structure 4 is the same. This way can also achieve the purpose of suppressing the leakage of acoustic wave energy.

[0083] The technical solution of the embodiment of the present invention can set a plurality of second protrusion structures on the basis of the first protrusion structure, change the distribution of the protrusions in the working area, and improve the performance of the thin film bulk acoustic wave resonator.

[0084] Optionally, Figure 6 is a top view of the fourth thin film bulk acoustic wave resonator provided according to the embodiment of the present invention. As Figure 6 shown, it further includes a third protrusion structure 7;

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

[0086] Along the thickness direction y of the thin film bulk acoustic wave resonator, the projection of the working area on the plane where the substrate 1 is located covers the projection of the third protrusion structure 7 on the plane where the substrate 1 is located.

[0087] Among them, the first protrusion structure 4, the second protrusion structure 5 and the third protrusion structure 7 can be arranged on the same side of the temperature compensation layer 3 and formed simultaneously. The first protrusion structure 4, the second protrusion structure 5 and the third protrusion structure 7 are arranged at intervals, so that when the transducer stack structure 2 is prepared later, a first protrusion 40, a second protrusion 50 and a third protrusion 70 are formed on the surface of the transducer stack structure 2, further achieving the purpose of suppressing the leakage of acoustic wave energy.

[0088] Specifically, on the basis that the first protrusion structure 4 ensures the leakage of acoustic wave energy, the setting method of the third protrusion structure 7 can be determined according to requirements. For example, as Figure 6 shown, both the first protrusion structure 4 and the second protrusion structure 5 are closed figures with the same shape. The third protrusion structure 7 is multiple and is arranged periodically between the first protrusion structure 4 and the second protrusion structure 5, and each third protrusion structure 7 is parallel to both the first protrusion structure 4 and the second protrusion structure 5; Figure 7 is a top view of the fifth thin film bulk acoustic wave resonator provided according to the embodiment of the present invention. As Figure 7As shown, the first protrusion structure 4 is a closed figure with the same shape. The second protrusion structure 5 includes multiple parts that are periodically arranged and parallel to a part of the first protrusion structure 4. The third protrusion structure 7 also includes multiple parts that are periodically arranged and parallel to a part of the first protrusion structure 4. The second protrusion structure 5 and the third protrusion structure 7 are not parallel; Figure 8 is a top view of the sixth thin film bulk acoustic resonator provided by an embodiment of the present invention, as Figure 8 shown, both the first protrusion structure 4 and the second protrusion structure 5 are closed figures with the same shape. The third protrusion structure 7 is cylindrical and is periodically arranged between the first protrusion structure 4 and the second protrusion structure 5.

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

[0090] Optionally, continue to refer to Figure 1 shown, the transducer stack structure 2 includes a bottom electrode layer 21, a piezoelectric layer 22, and a top electrode layer 23 that are stacked;

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

[0092] Among them, 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] Among them, by disposing the temperature compensation layer 3 in the piezoelectric layer 22, it is necessary to first grow the piezoelectric layer 22 when preparing the temperature compensation layer 3, then prepare the temperature compensation layer 3 and the first protrusion structure 4, and then cover the piezoelectric layer 22 after preparation, so as to achieve the purpose of disposing the temperature compensation layer 3 in the piezoelectric layer 22. The first protrusion structure 4 forms protrusions on the surface of the piezoelectric layer 22 and forms the 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 disposed in the bottom electrode layer 21 or in the top electrode layer 23, as long as protrusions are formed on the surface of the transducer stack structure 2.

[0095] In the technical solution of the embodiment of the present invention, by disposing a temperature compensation layer in the piezoelectric layer, during the subsequent film deposition process, protrusions can be formed on the surface of the thin film bulk acoustic wave resonator, which can avoid unnecessary vibrations or damping and reduce energy loss caused by other non-resonances. Thus, while reducing the frequency temperature drift of the thin film bulk acoustic wave resonator, the Q value of the thin film bulk acoustic wave resonator is improved.

[0096] Based on the same inventive concept, Figure 9 FIG. 5 is a flowchart of a method for manufacturing a first thin film bulk acoustic wave resonator according to an embodiment of the present invention. Figure 10 FIG. 6 is a schematic structural diagram corresponding to the method for manufacturing a first thin film bulk acoustic wave resonator according to an embodiment of the present invention. As shown in conjunction with Figure 9 and Figure 10 FIG. 7, an embodiment of the present invention provides a method for manufacturing a thin film bulk acoustic wave resonator, which is used to manufacture a thin film bulk acoustic wave resonator. The manufacturing method includes:

[0097] S10. Provide a substrate. As shown in step (a) of FIG. 4. Figure 10 Among them, the substrate 1 can be used as the base of the thin film bulk acoustic wave resonator, and a silicon material substrate 1 can be selected in the actual manufacturing process.

[0098]

[0099] Figure 10 S11. Prepare 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 FIG. 4. Among them, 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-elastic coefficient of the temperature compensation layer 3 is greater than zero, and the temperature-elastic coefficient of the transducer stack structure 2 is less than zero; Figure 10

[0100] The transducer stack structure 2 includes a working area; along the thickness direction y of the thin film bulk acoustic wave 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 to the side surface of the temperature compensation layer 3.

[0101] 2 2 2 Among them, the temperature compensation layer 3 can be made of a material with a positive temperature-elastic coefficient. For example, SiO 2 2 2

[0102] Among them, the first convex structure 4 is disposed 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 by growing continuously on one side of the temperature compensation layer 3. After preparing the first convex structure 4 on the temperature compensation layer 3 and then stacking other film layers, since the thickness of the prepared film layer is fixed, a first convex 40 is formed on the surface of the thin film bulk acoustic wave resonator. When the first convex 40 works in the working area of the transducer stacking structure 2, unnecessary vibration or damping can be avoided, and energy loss caused by other non-resonances can be reduced.

[0103] Exemplarily, a 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 the first convex structure 4 is prepared at the corresponding position after the temperature compensation layer 3 is prepared; after the first convex structure 4 is prepared, the piezoelectric layer 22 is continuously deposited to cover the temperature compensation layer 3 and the first convex structure 4. There is a first convex 40 on the surface of the piezoelectric layer 22 at the corresponding position of the first convex structure 4. The top electrode layer 23 is continuously deposited, and there is also a first convex 40 at the corresponding position of the top electrode layer 23, and the preparation of the thin film bulk acoustic wave resonator is completed.

[0104] The technical solution of the embodiment of the present invention prepares a temperature compensation layer in the thin film bulk acoustic wave resonator, and prepares the first convex structure while preparing the temperature compensation layer. Through the deposition of subsequent stacked thin films, a corresponding first convex can be formed on the top of the thin film bulk acoustic wave resonator, which can avoid unnecessary vibration or damping, reduce energy loss caused by other non-resonances, and improve the Q value of the thin film bulk acoustic wave resonator while reducing the frequency temperature drift of the thin film bulk acoustic wave resonator.

[0105] On the basis of the above embodiment, Figure 11 is a flowchart of a second method for preparing a thin film bulk acoustic wave resonator according to an embodiment of the present invention, Figure 12 is a schematic structural diagram corresponding to the second method for preparing a thin film bulk acoustic wave resonator according to an embodiment of the present invention. Combining Figure 11 and Figure 12 as shown, the preparation method includes:

[0106] S20. Provide a substrate. As shown in step (c) of Figure 12 .

[0107] S21. Prepare a transducer stacking structure, a temperature compensation layer, a first convex structure and a second convex structure on one side of the substrate. As shown in step (d) of Figure 12 . Among them, the second convex structure 5 is located on the side of the temperature compensation layer 3 away from the substrate 1 and is spaced from the first convex structure 4;

[0108] Along the thickness direction y of the thin film bulk acoustic wave resonator, the projection of the working area on the plane where the substrate 1 is located covers the projection of the second convex structure 5 on the plane where the substrate 1 is located; the projection of the second convex structure 5 on the plane where the substrate 1 is located is parallel to the projection of the first convex structure 4 on the plane where the substrate 1 is located.

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

[0110] The technical solution of the embodiment of the present invention can prepare the second convex structure while preparing the first convex structure, change the distribution of the convexes on the working area, and thus ensure the propagation effect of the acoustic wave in the working area while improving the performance of the thin film bulk acoustic wave resonator.

[0111] On the basis of the above embodiment, Figure 13 is a flowchart of the preparation method of the third thin film bulk acoustic wave resonator provided by the embodiment of the present invention, Figure 14 is a schematic structural diagram corresponding to the preparation method of the third thin film bulk acoustic wave resonator provided by the embodiment of the present invention. As shown in combination with Figure 13 and Figure 14 shown, the preparation method includes:

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

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

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

[0115] Wherein, since the temperature compensation layer 3 and the first convex structure 4 need to be arranged on the piezoelectric layer 22, the piezoelectric layer 22 needs to be prepared in two steps. The piezoelectric layer 22 is prepared in S32 to facilitate the growth of the temperature compensation layer 3.

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

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

[0118] Among them, the first convex structure 4 and the temperature compensation layer 3 can be made of the same material or different materials. When they are made of the same material, the first convex structure 4 can be formed by etching the temperature compensation layer 3, or can be formed by two depositions and patterned etching; when different materials are selected, the first convex structure 4 can be deposited after the temperature compensation layer 3 is deposited.

[0119] S35. Grow the piezoelectric layer and the top electrode layer again on the side of the first convex structure away from the piezoelectric layer. As Figure 14 shown in step (j) of

[0120] Among them, the piezoelectric layer 22 and the top electrode layer 23 are grown again on the side of the first convex structure 4 away from the piezoelectric layer 22, so that a first convex 40 is formed on the surfaces of the piezoelectric layer 22 and the top electrode layer 23, achieving the purpose of suppressing the energy loss caused by non-resonance.

[0121] The technical solution of the embodiment of the present invention, by arranging the temperature compensation layer in the piezoelectric layer, enables convexes to be formed on the surface of the thin film bulk acoustic resonator during the subsequent film deposition process, can avoid unnecessary vibrations or damping, and reduce the energy loss caused by other non-resonances, thereby reducing the frequency temperature drift of the thin film bulk acoustic resonator and improving the Q value of the thin film bulk acoustic resonator at the same time.

[0122] It should be understood that the various forms of the processes shown above can be used, reordering, adding or deleting steps. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitations are imposed herein.

[0123] The above specific embodiments do not constitute a limitation to 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 resonator, characterized in that: include: A substrate, a transducer stack structure, a temperature compensation layer and a first protrusion structure; The transducer stack structure is located on one side of the substrate; The temperature compensation layer and the first protrusion structure are located inside the transducer stack structure, and the first protrusion structure is located on a side of the temperature compensation layer away from the substrate, and is used to form a first protrusion on a surface of the transducer stack structure away from the substrate; the temperature-elastic coefficient of the temperature compensation layer is greater than zero, and the temperature-elastic coefficient of the transducer stack structure is less than zero; The transducer stacking structure includes a working area; along the thickness direction of the thin film bulk acoustic wave resonator, the projection of the temperature compensation layer on the plane where the substrate is located covers the 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 the projection of the first protruding structure on the plane where the substrate is located, and the first protruding structure is connected to the side of the temperature compensation layer.

2. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: Along the thickness direction of the thin film bulk acoustic wave resonator, the projection of the first protruding structure on the plane where the substrate is located is a closed figure.

3. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: Also included is a second raised structure; The second protrusion structure is located on a side of the temperature compensation layer away from the substrate and is spaced apart from the first protrusion structure, and is used to form a second protrusion on a surface of the transducer stack structure away from the substrate; Along the thickness direction of the thin film bulk acoustic wave 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.

4. The thin film bulk acoustic wave resonator according to claim 3, characterized in that: The second protrusion structure comprises at least two; Each of the second protruding structures is spaced the same distance from the first protruding structures.

5. The thin film bulk acoustic wave resonator according to claim 3, characterized in that: Also included is a third raised structure; The third protrusion structure is located on a side of the temperature compensation layer away from the substrate and is disposed between the first protrusion structure and the second protrusion structure, and is used to form a third protrusion on a surface of the transducer stack structure away from the substrate; Along the thickness direction of the thin film bulk acoustic wave resonator, the projection of the working area on the plane where the substrate is located covers the projection of the third protruding structure on the plane where the substrate is located.

6. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The width of the first protrusion structure is less than 10 μm.

7. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The transducer stack structure includes a bottom electrode layer, a piezoelectric layer and a top electrode layer stacked; The temperature compensation layer is disposed in the piezoelectric layer.

8. A method for preparing a thin film bulk acoustic wave resonator, characterized in that: Used to prepare the thin film bulk acoustic wave resonator according to any one of claims 1 to 7; the preparation method comprises: providing a substrate; A transducer stack structure, a temperature compensation layer and a first protruding structure are prepared 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 a side of the temperature compensation layer away from the substrate; the temperature-elastic coefficient of the temperature compensation layer is greater than zero, and the temperature-elastic coefficient of the transducer stack structure is less than zero; The transducer stacking structure includes a working area; along the thickness direction of the thin film bulk acoustic wave resonator, the projection of the temperature compensation layer on the plane where the substrate is located covers the 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 the projection of the first protruding structure on the plane where the substrate is located, and the first protruding structure is connected to the side of the temperature compensation layer.

9. The preparation method according to claim 8, characterized in that: A transducer stack structure, a temperature compensation layer and a first protrusion structure are prepared on one side of the substrate, including: A transducer stack structure, a temperature compensation layer, a first protrusion structure and a second protrusion structure are prepared on one side of the substrate; wherein the second protrusion structure is located on a side of the temperature compensation layer away from the substrate and is spaced apart from the first protrusion structure; Along the thickness direction of the thin film bulk acoustic wave 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: A transducer stack structure, a temperature compensation layer and a first protrusion structure are prepared on one side of the substrate, including: Growing a bottom electrode layer on one side of the substrate; Growing a piezoelectric layer on a side of the bottom electrode layer away from the substrate; Growing a temperature compensation layer on a side of the piezoelectric layer away from the bottom electrode layer; Prepare a first protrusion structure on a side of the temperature compensation layer away from the piezoelectric layer; The piezoelectric layer and the top electrode layer are grown again on the side of the first protrusion structure away from the piezoelectric layer.

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