Piezoelectric thin film bulk acoustic resonator

Abstract

The application provides a piezoelectric thin film bulk acoustic resonator, comprising: a substrate, a bottom electrode located on one side of the substrate, a piezoelectric layer covering one side of the bottom electrode away from the substrate, a top electrode located on one side of the piezoelectric layer away from the bottom electrode, an etching insertion layer located on one side of the top electrode away from the piezoelectric layer, and a convex frame located on one side of the etching insertion layer away from the top electrode; at least one of the etching insertion layer and the convex frame is provided with an extension part, the extension part is located at the edge of an effective source area, and the extension part extends in a direction away from the effective source area along a direction perpendicular to the thickness direction of the piezoelectric thin film bulk acoustic resonator. By arranging the extension part, the first extreme point, the second extreme point and the third extreme point of the quality factor of the piezoelectric thin film bulk acoustic resonator of the application are obviously increased compared with the prior art.

Description

[Technical Field]

[0001] This application relates to the field of resonator technology, and in particular to a piezoelectric thin film bulk acoustic resonator. [Background Technology]

[0002] A piezoelectric thin-film bulk acoustic resonator is a resonator manufactured using a silicon substrate with the aid of microelectromechanical systems and thin-film technology. In wireless transceivers, it can achieve functions such as image cancellation, parasitic filtering, and channel selection.

[0003] Existing piezoelectric thin-film bulk acoustic resonators include a substrate, a bottom electrode, a piezoelectric layer, a top electrode, an etched insertion layer, and an annular protrusion frame stacked along their thickness direction. The overlapping area of ​​the bottom electrode, piezoelectric layer, top electrode, and etched insertion layer constitutes the effective source region of the piezoelectric thin-film bulk acoustic resonator. Along the thickness direction of the piezoelectric thin-film bulk acoustic resonator, the projected profile of the protrusion frame is located at the edge of the effective source region. The protrusion frame is used to reflect part of the laterally propagating Rayleigh-Lamb wave (RL wave) back into the effective source region.

[0004] RL waves mainly have four modes: S0, A0, S1, and A1, and each mode has a different wavelength. When the width of the raised frame is equal to an odd multiple of 1 / 4 of the wavelength of the RL wave in a certain mode, the reflection efficiency of the raised frame is the highest. Since the width of the raised frame cannot be adjusted after manufacturing, the raised frame can only reflect RL waves in a single mode. When the RL wave is in other modes, the energy leakage at the edge of the effective source region is large, resulting in a low quality factor of the piezoelectric thin film bulk acoustic resonator.

[0005] Therefore, it is necessary to provide a piezoelectric thin film bulk acoustic resonator with a high quality factor. [Summary of the Invention]

[0006] The purpose of this application is to provide a piezoelectric thin film bulk acoustic resonator with a high quality factor.

[0007] The technical solution of this application is as follows:

[0008] Piezoelectric thin film bulk acoustic resonators include:

[0009] Substrate;

[0010] Along the thickness direction of the piezoelectric thin film bulk acoustic resonator, there is a bottom electrode on one side of the substrate, a piezoelectric layer covering the side of the bottom electrode away from the substrate, a top electrode on the side of the piezoelectric layer away from the bottom electrode, an etched insertion layer on the side of the top electrode away from the piezoelectric layer, and a protruding frame on the side of the etched insertion layer away from the top electrode.

[0011] The stacked region of the bottom electrode, piezoelectric layer, top electrode, and etched insertion layer constitutes at least a portion of the effective source region of the piezoelectric thin film bulk acoustic resonator;

[0012] In the etched insertion layer and the protrusion frame, at least one of them is provided with an extension. The extension is located at the edge of the effective source region and extends in a direction away from the effective source region along the thickness direction perpendicular to the piezoelectric thin film bulk acoustic resonator.

[0013] In some embodiments, along the thickness direction of the piezoelectric thin film bulk acoustic resonator, the projected profile of the extension is located within the projected profile of the bottom electrode.

[0014] In some embodiments, along the thickness direction perpendicular to the piezoelectric thin film bulk acoustic resonator, the extension length L of the extension satisfies: L≥0.5μm.

[0015] In some embodiments, both the etched insertion layer and the protrusion frame are provided with extensions, the extension on the etched insertion layer is a first extension, and the extension on the protrusion frame is a second extension.

[0016] Along the extension direction of the extension, the extension length of the first extension may be the same as or different from the extension length of the second extension.

[0017] In some embodiments, the substrate is provided with a cavity, which extends through one side of the substrate along the thickness direction of the piezoelectric thin film bulk acoustic resonator.

[0018] The bottom electrode covers the cavity.

[0019] In some embodiments, along the thickness direction of the piezoelectric thin film bulk acoustic resonator, the size of the bottom electrode projected onto the substrate is equal to or greater than the size of the cavity, and the size of the top electrode projected onto the substrate is less than or equal to the size of the cavity.

[0020] In some embodiments, the etched insertion layer includes a dielectric material, which is aluminum nitride or silicon nitride.

[0021] In some embodiments, the protruding frame includes a first metallic material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the first metallic material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium.

[0022] In some embodiments, the bottom electrode includes a second metallic material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the second metallic material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium;

[0023] The top electrode includes a third metallic material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the third metallic material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium.

[0024] In some embodiments, the piezoelectric layer includes a piezoelectric material, which is one of aluminum nitride, zinc oxide, titanium lead zirconate, lithium niobate, and lithium tantalate; or, the piezoelectric material is a composite piezoelectric material formed from at least two of aluminum nitride, zinc oxide, titanium lead zirconate, lithium niobate, and lithium tantalate.

[0025] The beneficial effects of this application are as follows: By providing the extension, the first, second, and third extreme points of the quality factor of the piezoelectric thin-film bulk acoustic resonator of this application are significantly increased compared to the prior art, with the first extreme point showing the largest increase. Furthermore, since the extension does not additionally reduce the effective electromechanical coupling coefficient (k²eff) of the piezoelectric thin-film bulk acoustic resonator, selecting a smaller width for the protruding frame corresponding to the first extreme point allows the piezoelectric thin-film bulk acoustic resonator to simultaneously possess a high quality factor and a large effective electromechanical coupling coefficient (k²eff). [Attached Image Description]

[0026] Figure 1 A schematic diagram of the structure of the piezoelectric thin film bulk acoustic resonator provided in this application in one embodiment;

[0027] Figure 2 for Figure 1 Top view;

[0028] Figure 3 for Figure 1 Cross-sectional view along the thickness direction of a piezoelectric thin film bulk acoustic resonator;

[0029] Figure 4 A schematic diagram of the structure of the piezoelectric thin film bulk acoustic resonator provided in this application in another embodiment;

[0030] Figure 5 for Figure 4 Top view;

[0031] Figure 6 for Figure 4 Cross-sectional view along the thickness direction of a piezoelectric thin film bulk acoustic resonator;

[0032] Figure 7 for Figure 4 A schematic diagram of the structure of the etching insertion layer in one embodiment;

[0033] Figure 8 for Figure 7 A bottom view;

[0034] Figure 9 for Figure 4 A schematic diagram of the structure of the central protrusion frame in one embodiment;

[0035] Figure 10 for Figure 9 A bottom view;

[0036] Figure 11 A comparison curve of the quality factor of the piezoelectric thin film bulk acoustic resonator provided in this application and the piezoelectric thin film bulk acoustic resonator of the prior art.

[0037] Figure 12 A comparison curve of the effective electromechanical coupling coefficient (k2eff) between the piezoelectric thin film bulk acoustic resonator provided in this application and the piezoelectric thin film bulk acoustic resonator of the prior art.

[0038] Figure label:

[0039] 1-Substrate;

[0040] 11-Cavity;

[0041] 2- Bottom electrode;

[0042] 3-Piezoelectric layer;

[0043] 4-Top electrode;

[0044] 5-Etching the insertion layer;

[0045] 51-First extension;

[0046] 52 - First Accommodation Space;

[0047] 6-Protruding frame;

[0048] 61-Second extension;

[0049] 62 - Second containment space;

[0050] 63 - Third Accommodation Space;

[0051] S1 - Valid source region;

[0052] S11 - First Area;

[0053] S12 - Second Region;

[0054] S2 - Third Region;

[0055] S3 - Fourth Region.

Detailed Implementation Methods

[0056] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0057] This application provides a piezoelectric thin film bulk acoustic resonator. The outer contour of the piezoelectric thin film bulk acoustic resonator can be rectangular, pentagonal, hexagonal, elliptical or other deformed structures. This application takes a rectangular outer contour of the piezoelectric thin film bulk acoustic resonator as an example.

[0058] like Figures 1 to 6As shown, the piezoelectric thin-film bulk acoustic resonator includes: a substrate 1; a bottom electrode 2 located on one side of the substrate 1 along the thickness direction of the piezoelectric thin-film bulk acoustic resonator; a piezoelectric layer 3 covering the side of the bottom electrode 2 away from the substrate 1; a top electrode 4 located on the side of the piezoelectric layer 3 away from the bottom electrode 2; an etched insertion layer 5 located on the side of the top electrode 4 away from the piezoelectric layer 3; and a raised frame 6 located on the side of the etched insertion layer 5 away from the top electrode 4; the stacked region of the bottom electrode 2, the piezoelectric layer 3, the top electrode 4, and the etched insertion layer 5 constitutes at least a portion of the effective source region S1 of the piezoelectric thin-film bulk acoustic resonator; at least one of the etched insertion layer 5 and the raised frame 6 is provided with an extension, the extension is located at the edge of the effective source region S1, and extends in a direction away from the effective source region S1 along the thickness direction perpendicular to the piezoelectric thin-film bulk acoustic resonator.

[0059] Among them, such as Figure 2 , Figure 3 , Figure 5 and Figure 6 As shown, the effective source region S1 includes a first region S11 and a second region S12. In the plane enclosed by the length direction X and the width direction Y of the piezoelectric thin film bulk acoustic resonator (for ease of description, the following will use a horizontal plane as an example), the first region S11 is located in the middle part of the protruding frame 6, that is, the exposed part of the top electrode 4. The second region S12 is the part from the inner edge of the protruding frame 6 to the outer edge of the top electrode 4. The part from the outer edge of the top electrode 4 to the outer edge of the extension is the third region S2. The part from the outer edge of the extension to the outer edge of the piezoelectric layer 3 is the fourth region S3.

[0060] When the piezoelectric thin film bulk acoustic resonator is working, the bottom electrode 2 and the top electrode 4 are electrically connected to the power supply. The power supply applies an alternating current to the top electrode 4 and the bottom electrode 2, causing the top electrode 4 and the bottom electrode 2 to drive the piezoelectric layer 3 to vibrate, thereby generating an effective sound wave that propagates along the thickness direction Z of the piezoelectric thin film bulk acoustic resonator and a Rayleigh-Lamb wave (RL wave) that propagates along the length direction X and / or the width direction Y of the piezoelectric thin film bulk acoustic resonator (i.e., transverse propagation).

[0061] When the width of the raised frame 6 is determined, most of the energy of the single-mode RL wave that matches the width of the raised frame 6 will be reflected back to the effective source region S1 from the boundary between the second region S12 and the third region S2 (for ease of explanation, the S0 mode will be used as an example below), reducing the energy leakage of the S0 mode RL wave from the edge of the effective source region S1; part of the energy of the A0 mode, S1 mode and A1 mode RL waves will propagate into the third region S2. Due to the different acoustic impedances of the third region S2 and the fourth region S3, the leaked A0 mode, S1 mode and A1 mode RL waves will be reflected back to the effective source region S1 from the boundary between the third region S2 and the fourth region S3, and can be converted into piston acoustic wave mode (i.e. effective acoustic wave) propagating along the thickness direction Z of the piezoelectric thin film bulk acoustic resonator, reducing the energy leakage of the A0 mode, S1 mode and A1 mode RL waves from the edge of the effective source region S1, thereby effectively improving the quality factor of the piezoelectric thin film bulk acoustic resonator. By providing an extension on the raised frame 6 and / or the etched insertion layer 5, the reflectable RL wave is increased, reducing the limitations of the piezoelectric thin film bulk acoustic resonator and thus improving its performance and applicability.

[0062] The reflection coefficient of the sound wave reflected back from the RL wave in A0 mode, S1 mode, and A1 mode, and the conversion efficiency from RL wave to effective sound wave can be adjusted by adjusting the extension length of the extension section.

[0063] Furthermore, since the extension is located outside the effective source region S1, it does not generate parasitic effects or load effects, and does not additionally reduce the effective electromechanical coupling coefficient (k2eff) of the piezoelectric thin film bulk acoustic resonator.

[0064] Specifically, such as Figure 3 and Figure 6 As shown, along the thickness direction Z of the piezoelectric thin film bulk acoustic resonator, the projected profile of the extension is located within the projected profile of the bottom electrode 2.

[0065] In this embodiment, if the outer contour of the extension exceeds the outer contour of the bottom electrode 2, the extension cannot divide the outer side of the effective source region S1 into the third region S2 and the fourth region S3. This results in some RL waves not being reflected back into the effective source region S1, thereby reducing the quality factor of the piezoelectric thin-film bulk acoustic resonator. Therefore, along the thickness direction Z of the piezoelectric thin-film bulk acoustic resonator, the projected contour of the extension lies within the projected contour of the bottom electrode 2, improving the reflection stability of the extension for RL waves and thus improving the quality factor of the piezoelectric thin-film bulk acoustic resonator.

[0066] Wherein, along the length direction X and / or width direction Y of the piezoelectric thin film bulk acoustic resonator perpendicular to the thickness direction of the piezoelectric thin film bulk acoustic resonator, the extension length L satisfies: L≥0.5μm. Specifically, the extension length of the extension can be 0.5μm, 1μm, 1.5μm, 2μm, 2.6μm, 3μm, etc.

[0067] If the extension length of the extension is small, i.e., L < 0.5 μm, the energy of the RL wave reflected by the extension is less. Therefore, L ≥ 0.5 μm can enhance the reflection effect of the extension on the RL wave, increase the energy of the RL wave reflected by the extension, and thus further improve the quality factor of the piezoelectric thin film bulk acoustic resonator.

[0068] In one embodiment, such as Figure 1 , Figure 2 and Figure 3 As shown, only the etched insertion layer 5 has an extension to simplify the structure of the protruding frame 6 and reduce the processing cost of the protruding frame 6.

[0069] The extension portion and the etched insertion layer 5 can be integrally formed or separately configured to increase the structural flexibility of the extension portion and the etched insertion layer 5. The extension portion and the etched insertion layer 5 can be made of the same or different materials to increase the replaceability of the extension portion and the etched insertion layer 5, thereby reducing the processing and maintenance costs of the extension portion and the etched insertion layer 5.

[0070] In another embodiment, an extension is provided only on the protruding frame 6 to simplify the structure of the etching insertion layer 5 and reduce the processing cost of the etching insertion layer 5.

[0071] The extension portion and the raised frame 6 can be integrally formed or separately configured to increase the structural flexibility of the extension portion and the raised frame 6. The extension portion and the raised frame 6 can be made of the same or different materials to increase the replaceability of the extension portion and the raised frame 6, thereby reducing the processing and maintenance costs of the extension portion and the raised frame 6.

[0072] In another embodiment, such as Figure 4 , Figure 5 and Figure 6 As shown, both the etched insertion layer 5 and the raised frame 6 are provided with extensions. The extension on the etched insertion layer 5 is the first extension 51, and the extension on the raised frame 6 is the second extension 61.

[0073] Specifically, such as Figure 7 and Figure 8 As shown, the etched insertion layer 5 has a first receiving space 52. Along the thickness direction Z of the piezoelectric thin film bulk acoustic resonator, the first receiving space 52 penetrates one side of the etched insertion layer 5, as shown. Figure 6As shown, the top electrode 4 is mounted in the first receiving space 52, and the edge of the top electrode 4 abuts against the sidewall of the first receiving space 52; the etched insertion layer 5 extends along the length direction X and / or width direction Y of the piezoelectric thin film bulk acoustic resonator at the edge of the opening of the first receiving space 52 to form a first extension 51, as shown. Figure 6 As shown, the first extension 51 abuts against the piezoelectric layer 3, and the top electrode 4 is clamped and fixed by the piezoelectric layer 3 and the etched insertion layer 5.

[0074] like Figure 9 and Figure 10 As shown, the protruding frame 6 includes a second receiving space 62 and a third receiving space 63 disposed opposite each other along the thickness direction Z of the piezoelectric thin film bulk acoustic resonator. The second receiving space 62 penetrates one side of the protruding frame 6, and the third receiving space 63 penetrates the other side of the protruding frame 6. The second receiving cavity communicates with the third receiving space 63. The edge of the protruding frame 6 at the opening of the second receiving space 62 extends along the length direction X and / or width direction Y of the piezoelectric thin film bulk acoustic resonator to form a second extension 61, as shown. Figure 6 As shown, a portion of the etched insertion layer 5 is located within the second receiving space 62 and abuts against the sidewall of the second receiving space 62. The second extension 61 abuts against the first extension 51. A portion of the etched insertion layer 5 is exposed through the third receiving space 63. The area enclosed by the third receiving space 63 is the first region S11 of the effective source region S1.

[0075] Wherein, along the extension direction of the extension portion, that is, along the length direction X and / or width direction Y of the piezoelectric thin film bulk acoustic resonator, the extension length of the first extension portion 51 and the extension length of the second extension portion 61 can be the same or different, so as to increase the structural flexibility of the first extension portion 51 and the second extension portion 61. In this embodiment, the edges of the first extension portion 51 and the second extension portion 61 are located in the same plane in the thickness direction Z of the piezoelectric thin film bulk acoustic resonator.

[0076] Furthermore, the material of the first extension 51 and the material of the second extension 61 may be the same or different.

[0077] Specifically, substrate 1 is provided with an acoustic reflection structure, which can be a closed cavity formed inside substrate 1 (not shown in the figure); or, as... Figure 3 and Figure 6 As shown, the acoustic reflection structure is a cavity 11 formed on the substrate 1. Along the thickness direction Z of the piezoelectric thin film bulk acoustic resonator, the cavity 11 penetrates one side of the substrate 1, and the bottom electrode 2 covers the cavity 11; or, the acoustic reflection structure is a Bragg reflector (not shown in the figure) formed on the surface of the substrate 1.

[0078] In this embodiment, the acoustic reflection structure is a sealed cavity 11 inside the substrate 1, a cavity penetrating one side of the substrate 1, or a Bragg reflector. This increases the flexibility of the acoustic reflection structure, allowing for flexible configuration according to actual needs during production and processing, thereby expanding the applicability of the piezoelectric thin-film bulk acoustic resonator. In this embodiment, the acoustic reflection structure is a cavity penetrating one side of the substrate 1, simplifying the structure of the substrate 1, reducing the production cost of the substrate 1, and thus reducing the cost of the piezoelectric thin-film bulk acoustic resonator. Simultaneously, since the cavity penetrates one side of the substrate 1, meaning the cavity is exposed outside the substrate 1, the size and contour shape of the cavity can be adjusted according to requirements during the use of the piezoelectric thin-film bulk acoustic resonator, thereby improving the working stability and reliability of the piezoelectric thin-film bulk acoustic resonator.

[0079] Specifically, such as Figure 3 and Figure 6 As shown, along the thickness direction of the piezoelectric thin film bulk acoustic resonator, the size of the bottom electrode 2 projected onto the substrate 1 is equal to or greater than the size of the cavity 11, and the size of the top electrode 4 projected onto the substrate 1 is less than or equal to the size of the cavity 11.

[0080] In this embodiment, the size of the bottom electrode 2 is equal to or greater than the size of the cavity 11, which reduces the risk of the bottom electrode 2 tilting into the cavity 11 when it covers the cavity 11, thereby improving the stability and reliability of the bottom electrode 2 installation, and thus improving the working stability of the piezoelectric thin film bulk acoustic resonator.

[0081] In any of the above embodiments, the etched insertion layer 5 includes a dielectric material, which is aluminum nitride or silicon nitride.

[0082] In this embodiment, aluminum nitride and silicon nitride have strong dielectric properties, that is, aluminum nitride and silicon nitride have good electrical insulation properties. The etching insertion layer 5 includes aluminum nitride or silicon nitride, which increases the electrical insulation performance of the etching insertion layer 5 and reduces the risk of short circuit of the top electrode 4 caused by etching the insertion layer 5 during the operation of the piezoelectric thin film bulk acoustic resonator. This improves the working stability of the top electrode 4 and the piezoelectric thin film bulk acoustic resonator and helps to extend the service life of the top electrode 4 and the piezoelectric thin film bulk acoustic resonator.

[0083] In any of the above embodiments, the protruding frame 6 includes a first metallic material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the first metallic material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium.

[0084] In this embodiment, when the first metal material is aluminum, the first metal material has good ductility, which facilitates the processing of the protruding frame 6 and reduces the processing cost of the protruding frame 6; when the first metal material is molybdenum or tungsten, the first metal material has strong hardness, which improves the structural stability of the protruding frame 6 and helps to extend the service life of the protruding frame 6; when the first metal material is tungsten or ruthenium, the first metal material has stable chemical properties, which reduces the risk of corrosion and oxidation of the protruding frame 6, thereby improving the structural stability of the protruding frame 6 and helping to extend the service life of the protruding frame 6.

[0085] In any of the above embodiments, the bottom electrode 2 includes a second metal material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the second metal material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium.

[0086] In this embodiment, when the second metal material is aluminum, the second metal material has good ductility, which facilitates the processing of the bottom electrode 2 and reduces the processing cost of the bottom electrode 2; when the second metal material is molybdenum or tungsten, the second metal material has strong hardness, which improves the structural stability of the bottom electrode 2 and helps to extend the service life of the bottom electrode 2; when the second metal material is tungsten or ruthenium, the second metal material has stable chemical properties, which reduces the risk of corrosion and oxidation of the bottom electrode 2, thereby improving the structural stability of the bottom electrode 2 and helping to extend the service life of the bottom electrode 2.

[0087] In any of the above embodiments, the top electrode 4 includes a third metal material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the third metal material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium.

[0088] In this embodiment, when the third metal material is aluminum, the third metal material has good ductility, which facilitates the processing of the top electrode 4 and reduces the processing cost of the top electrode 4; when the third metal material is molybdenum or tungsten, the third metal material has strong hardness, which improves the structural stability of the top electrode 4 and helps to extend the service life of the top electrode 4; when the third metal material is tungsten or ruthenium, the third metal material has stable chemical properties, which reduces the risk of corrosion and oxidation of the top electrode 4, thereby improving the structural stability of the top electrode 4 and helping to extend the service life of the top electrode 4.

[0089] The first metal material, the second metal material, and the third metal material can be the same or different.

[0090] In any of the above embodiments, the piezoelectric layer 3 includes a piezoelectric material, which is one of aluminum nitride, zinc oxide, titanium lead zirconate, lithium niobate, and lithium tantalate, or a composite piezoelectric material formed from at least two of aluminum nitride, zinc oxide, titanium lead zirconate, lithium niobate, and lithium tantalate.

[0091] In this embodiment, when the piezoelectric material is aluminum nitride, zinc oxide, titanium lead zirconate, lithium niobate, or lithium tantalate, the piezoelectric layer 3 achieves the highest piezoelectric tensor, which is beneficial to improving the acoustic wave conversion efficiency of the piezoelectric thin film bulk acoustic resonator.

[0092] In summary, by providing an extension portion and optimizing the extension length of the extension portion, the quality factor of the piezoelectric thin film bulk acoustic resonator can be further improved. For example... Figure 11 and Figure 12 As shown, when extensions are provided on both the etched insertion layer 5 and the protruding frame 6, the first, second, and third extreme points of the quality factor of the piezoelectric thin-film bulk acoustic resonator of this application are significantly increased compared to the prior art, with the first extreme point showing the largest increase. Furthermore, since the extensions do not additionally reduce the effective electromechanical coupling coefficient (k2eff) of the piezoelectric thin-film bulk acoustic resonator, selecting a smaller width for the protruding frame 6 corresponding to the first extreme point allows the piezoelectric thin-film bulk acoustic resonator to simultaneously possess a high quality factor and a large effective electromechanical coupling coefficient (k2eff).

[0093] The above description is merely an embodiment of this application. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this application, but these improvements all fall within the protection scope of this application.

Claims

1. A piezoelectric thin-film bulk acoustic resonator, characterized in that, The piezoelectric thin-film bulk acoustic resonator includes: Substrate; Along the thickness direction of the piezoelectric thin film bulk acoustic resonator, there is a bottom electrode located on one side of the substrate, a piezoelectric layer covering the bottom electrode on the side away from the substrate, a top electrode located on the side of the piezoelectric layer away from the bottom electrode, an etched insertion layer located on the side of the top electrode away from the piezoelectric layer, and a protruding frame located on the side of the etched insertion layer away from the top electrode. The stacked region of the bottom electrode, the piezoelectric layer, the top electrode, and the etched insertion layer constitutes the effective source region of the piezoelectric thin film bulk acoustic resonator, and a portion of the protruding frame is located within the effective source region; At least one of the etched insertion layer and the protrusion frame is provided with an extension, the extension is located at the edge of the effective source region and extends in a direction away from the effective source region along the thickness direction perpendicular to the piezoelectric thin film bulk acoustic resonator; The etched insertion layer includes a dielectric material.

2. The piezoelectric thin film bulk acoustic resonator according to claim 1, characterized in that, Along the thickness direction of the piezoelectric thin film bulk acoustic resonator, the projected profile of the extension is located within the projected profile of the bottom electrode.

3. The piezoelectric thin-film bulk acoustic resonator according to claim 2, characterized in that, Along the thickness direction perpendicular to the piezoelectric thin film bulk acoustic resonator, the extension length L of the extension portion satisfies: L≥0.5μm.

4. The piezoelectric thin-film bulk acoustic resonator according to claim 1, characterized in that, Both the etched insertion layer and the protruding frame are provided with the extension portion, the extension portion on the etched insertion layer is the first extension portion, and the extension portion on the protruding frame is the second extension portion; Along the extending direction of the extension portion, the extending length of the first extension portion may be the same as or different from the extending length of the second extension portion; The etched insertion layer completely covers the top electrode.

5. The piezoelectric thin-film bulk acoustic resonator according to claim 1, characterized in that, The substrate has a cavity, which extends through one side of the substrate along the thickness direction of the piezoelectric thin film bulk acoustic resonator. The bottom electrode covers the cavity.

6. The piezoelectric thin-film bulk acoustic resonator according to claim 5, characterized in that, Along the thickness direction of the piezoelectric thin film bulk acoustic resonator, the size of the bottom electrode projected onto the substrate is equal to or greater than the size of the cavity, and the size of the top electrode projected onto the substrate is less than or equal to the size of the cavity.

7. The piezoelectric thin-film bulk acoustic resonator according to any one of claims 1 to 6, characterized in that, The dielectric material is aluminum nitride or silicon nitride.

8. The piezoelectric thin film bulk acoustic resonator according to any one of claims 1 to 6, characterized in that, The protruding frame includes a first metallic material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the first metallic material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium.

9. The piezoelectric thin-film bulk acoustic resonator according to any one of claims 1 to 6, characterized in that, The bottom electrode includes a second metallic material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the second metallic material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium; The top electrode includes a third metallic material, which includes one of aluminum, molybdenum, tungsten, and ruthenium, or the third metallic material is a composite metal formed from at least two of aluminum, molybdenum, tungsten, and ruthenium.

10. The piezoelectric thin-film bulk acoustic resonator according to any one of claims 1 to 6, characterized in that, The piezoelectric layer includes a piezoelectric material, which is one of aluminum nitride, zinc oxide, titanium lead zirconate, lithium niobate, and lithium tantalate, or a composite piezoelectric material formed from at least two of aluminum nitride, zinc oxide, titanium lead zirconate, lithium niobate, and lithium tantalate.

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