Film bulk acoustic resonator and filter

Abstract

The invention discloses a film bulk acoustic resonator and a filter. The film bulk acoustic resonator comprises a substrate; the substrate comprises a sound reflecting layer; the first electrode is positioned on one side of the substrate; the piezoelectric layer is located on the side, away from the substrate, of the first electrode; the second electrode is located on the side, away from the substrate, of the piezoelectric layer; the first electrode, the piezoelectric layer and the second electrode are overlapped in an effective working area along the thickness direction of the film bulk acoustic resonator; the at least one temperature compensation layer is located between the substrate and the second electrode, and the temperature compensation layer and the effective working area are overlapped in the thickness direction of the film bulk acoustic wave resonator; the temperature compensation layer comprises a plurality of independently arranged temperature compensation structures. By adopting the technical scheme, the temperature drift can be reduced and the performance of the resonator can be improved by arranging the plurality of independently arranged temperature compensation structures, and the working frequency of the resonator can be adjusted by adjusting the area and the thickness of the temperature compensation structures.

Description

Technical Field

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

[0002] The rapid development of wireless communication technology and the increasing multifunctionality of communication terminals have placed higher demands on frequency devices operating in the radio frequency band. Compared with traditional dielectric ceramic filters and surface acoustic wave filters, filters based on thin-film bulk acoustic wave resonators can operate well in the range of several hundred MHz to 6-7 GHz. Especially in high-frequency applications, thin-film bulk acoustic wave filters have significant advantages. Thin-film bulk acoustic wave filters have characteristics such as high frequency, low loss, low temperature drift, steep filter skirt, extremely high Q value, operating frequency, sensitivity, resolution, power handling capacity, small size, and compatibility of manufacturing process with complementary metal-oxide-semiconductor (CMOS). Therefore, thin-film bulk acoustic wave resonators occupy most of the application areas of wireless communication.

[0003] As operating temperature changes, the resonant frequency of a thin-film bulk acoustic wave filter will shift. Because modern communication systems utilize multiple frequency bands and have small spacing between adjacent channels, temperature-induced frequency drift (temperature drift) can affect signal transmission in adjacent frequency bands, thus causing signal interference. Therefore, ensuring excellent temperature stability of the thin-film bulk acoustic wave filter is crucial for avoiding communication interference.

[0004] Existing methods for reducing the temperature 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. Typically, an entire layer of temperature compensation material is added to the structure of the thin-film bulk acoustic wave resonator. However, this can lead to a significant decrease in device performance, easily generate parasitic modes, and seriously affect signal transmission. Summary of the Invention

[0005] This invention provides a thin-film bulk acoustic resonator and filter to reduce temperature drift, improve resonator performance, and enable adjustable operating frequency of the resonator.

[0006] In a first aspect, embodiments of the present invention provide a thin-film bulk acoustic resonator, comprising:

[0007] Substrate; the substrate includes an acoustic reflective layer;

[0008] The first electrode is located on one side of the substrate;

[0009] A piezoelectric layer is located on the side of the first electrode away from the substrate;

[0010] The second electrode is located on the side of the piezoelectric layer away from the substrate; along the thickness direction of the thin-film bulk acoustic resonator, the first electrode, the piezoelectric layer, and the second electrode overlap in the effective working area;

[0011] At least one temperature compensation layer is located between the substrate and the second electrode, and overlaps with the effective working area along the thickness direction of the thin-film bulk acoustic resonator; the temperature compensation layer includes multiple independently arranged temperature compensation structures.

[0012] Optionally, multiple temperature compensation structures are located within the first electrode;

[0013] And / or, multiple of the temperature compensation structures are located within the second electrode;

[0014] Wherein, along the thickness direction of the thin-film bulk acoustic resonator, the first electrode includes a first surface away from the substrate, the second electrode includes a second surface away from the substrate, and the temperature compensation layer includes a third surface away from the substrate; the pattern of at least one of the first surface and the second surface is the same as the pattern of the third surface.

[0015] Optionally, at least one temperature compensation layer includes a first temperature compensation layer and a second temperature compensation layer; the first temperature compensation layer includes a plurality of first temperature compensation structures, and the second temperature compensation layer includes a plurality of second temperature compensation structures.

[0016] Along the thickness direction of the thin-film bulk acoustic resonator, the second electrode includes a first electrode portion and a second electrode portion; a plurality of first temperature compensation structures are located within the first electrode portion, and a plurality of second temperature compensation structures are located within the second electrode portion;

[0017] Along the first direction, a first gap is included between two adjacent first temperature compensation structures; along the thickness direction of the thin-film bulk acoustic resonator, the second temperature compensation structure overlaps with the first gap; the first direction intersects with the thickness direction of the thin-film bulk acoustic resonator.

[0018] Optionally, multiple temperature compensation structures are located within the piezoelectric layer.

[0019] Optionally, the distance between any two adjacent temperature compensation structures is the same.

[0020] Optionally, multiple temperature compensation structures are located within the second electrode;

[0021] Along the thickness direction of the thin-film bulk acoustic resonator, the second electrode includes a first electrode portion and a second electrode portion; the second electrode portion includes a main body portion and a plurality of protrusions; the protrusions are located on the side of the main body portion away from the substrate;

[0022] Along the first direction, a second gap is included between two adjacent protrusions; along the thickness direction of the thin-film bulk acoustic resonator, the temperature compensation structure overlaps with the second gap; the first direction intersects with the thickness direction of the thin-film bulk acoustic resonator.

[0023] Optionally, a plurality of the temperature compensation structures are located within the first electrode and a plurality of the temperature compensation structures are located within the second electrode;

[0024] Along the first direction, a third gap is included between two adjacent temperature compensation structures located within the first electrode; along the thickness direction of the thin-film bulk acoustic resonator, the temperature compensation structure located within the second electrode overlaps with the third gap; the first direction intersects with the thickness direction of the thin-film bulk acoustic resonator.

[0025] Optionally, the thin-film bulk acoustic resonator further includes a seed layer;

[0026] The seed layer is located between the substrate and the first electrode.

[0027] Optionally, the acoustic reflective layer includes a cavity;

[0028] Alternatively, the acoustic reflection layer may include a Bragg reflection layer; the Bragg reflection layer may include a first acoustic impedance layer and a second acoustic impedance layer, which are arranged alternately along the thickness direction of the bulk acoustic filter.

[0029] The acoustic impedance of the first acoustic impedance layer is different from that of the second acoustic impedance layer.

[0030] Secondly, embodiments of the present invention also provide a filter, including the thin-film bulk acoustic resonator described in any of the first aspects.

[0031] The technical solution provided by this invention reduces the drift of the resonator's operating frequency caused by changes in ambient temperature by providing at least one temperature compensation layer between the substrate and the second electrode. Specifically, the temperature compensation layer includes multiple independently configured temperature compensation structures. That is, the temperature compensation layer is not a single, continuous layer, but rather multiple independently configured temperature compensation structures formed by patterning and etching a single, continuous temperature compensation layer. Thus, by controlling the patterning and etching ratio of the temperature compensation layer, i.e., by adjusting the area ratio of the temperature compensation structures occupying the effective working area, the operating frequency of the thin-film bulk acoustic resonator can be adjusted. Attached Figure Description

[0032] Figure 1 This is a schematic cross-sectional view of the first type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0033] Figure 2 for Figure 1 Simulation diagram of the frequency of the first type of thin-film bulk acoustic resonator at different temperatures;

[0034] Figure 3 This is a schematic cross-sectional view of the second type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0035] Figure 4 This is a schematic cross-sectional view of the third type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0036] Figure 5 This is a schematic cross-sectional view of the fourth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0037] Figure 6 This is a schematic cross-sectional view of the fifth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0038] Figure 7 for Figure 6 A top-view diagram of the corresponding temperature compensation layer in the effective working area;

[0039] Figure 8 This is a schematic cross-sectional view of the sixth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0040] Figure 9 for Figure 8 A top-view diagram of the corresponding temperature compensation layer in the effective working area;

[0041] Figure 10 This is a schematic cross-sectional view of the seventh type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0042] Figure 11 for Figure 1 A top-view diagram of the corresponding temperature compensation layer in the effective working area;

[0043] Figure 12 This is a schematic cross-sectional view of the eighth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention;

[0044] Figure 13 A schematic cross-sectional view of the ninth type of thin-film bulk acoustic resonator provided in this embodiment of the invention;

[0045] Figure 14This is a schematic cross-sectional view of the tenth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0047] Figure 1 This is a schematic cross-sectional view of the first type of thin-film bulk acoustic resonator provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the thin-film bulk acoustic resonator includes: a substrate 10; an acoustic reflection layer 101 in the substrate 10; a first electrode 20 located on one side of the substrate 10; a piezoelectric layer 30 located on the side of the first electrode 20 away from the substrate 10; a second electrode 40 located on the side of the piezoelectric layer 30 away from the substrate 10; and a layer along the thickness direction of the thin-film bulk acoustic resonator (e.g., along the thickness direction of the substrate 10). Figure 1 (as shown in the Z direction), the first electrode 20, the piezoelectric layer 30, and the second electrode 20 overlap in the effective working area; at least one temperature compensation layer 60 is located between the substrate 10 and the second electrode 40, and overlaps with the effective working area along the thickness direction Z of the thin film bulk acoustic resonator; the temperature compensation layer 60 includes a plurality of independently disposed temperature compensation structures 601.

[0048] Specifically, the first electrode 20 can be understood as the bottom electrode, and the second electrode 40 as the top electrode. Along the thickness direction Z of the thin-film bulk acoustic resonator, the first electrode 20, the piezoelectric layer 30, and the second electrode 20 overlap in the effective working area, which can also be understood as the effective resonant region. The area outside the effective working area is the boundary region. When an electrical signal is applied to the first electrode 20 and the second electrode 40, acoustic waves are excited in the piezoelectric layer 30. These acoustic waves mainly propagate vertically in the working area. To confine these vertically propagating acoustic waves between the top and bottom electrodes, the upward-propagating acoustic waves are reflected back to the working area through the air-metal boundary at the top surface of the top electrode, and the downward-propagating acoustic waves are reflected back to the effective resonant region through the acoustic reflection layer 101.

[0049] Specifically, by providing at least one temperature compensation layer between the substrate 10 and the second electrode 40, and by overlapping the effective operating area along the thickness direction Z of the thin-film bulk acoustic resonator, the frequency drift of the resonator caused by changes in ambient temperature can be reduced. Furthermore, the temperature compensation layer 60 includes multiple independently configured temperature compensation structures 601. That is, the temperature compensation layer 60 is not a single, continuous layer, but rather multiple independently configured temperature compensation structures 601 formed by patterning and etching a single temperature compensation layer 601. Thus, by controlling the patterning and etching ratio of the temperature compensation layer, i.e., by adjusting the area of ​​the temperature compensation structures, the operating frequency of the thin-film bulk acoustic resonator can be adjusted.

[0050] It should be noted that in existing technologies, a single, continuous temperature compensation layer can cause separation between adjacent upper and lower film layers, which in turn affects the transmission path of the thin-film bulk acoustic resonator and leads to performance loss. However, the embodiments of this invention form multiple independent temperature compensation structures by etching the entire temperature compensation layer, connecting the adjacent upper and lower film layers. This effectively reduces the impact of the temperature compensation layer on the acoustic wave transmission path of the resonator, thereby minimizing its influence on resonator performance.

[0051] For example, the material of the temperature compensation layer 60 may be silicon dioxide or the like.

[0052] For example, the top view shape of the temperature compensation structure 601 can be rectangular, circular, or trapezoidal, etc. The embodiments of the present invention do not specifically limit the top view shape of the temperature compensation structure 601.

[0053] The present invention will be illustrated with an example where the temperature compensation layer 601 is located inside the second electrode 40. Figure 2 for Figure 1 The following table shows the simulation results of the first type of thin-film bulk acoustic resonator at different temperatures. Figure 2 The performance parameters of the corresponding thin-film bulk acoustic resonators are shown in the table below. Figure 2 :

[0054]

[0055] Specifically, Figure 2The gray solid line represents the technical solution where no temperature compensation layer is set in the thin-film bulk acoustic resonator, and the fitting function of frequency Y and temperature X is Y = 0.06X + 2546.6; the yellow solid line represents the thin-film bulk acoustic resonator with a temperature compensation layer of 10nm thickness, and the temperature compensation layer is located inside the second electrode, and the fitting function of frequency Y and temperature X is Y = 0.0567X + 2538.4; the blue solid line represents the technical solution of setting multiple independent temperature compensation structures of 10nm thickness inside the second electrode in the embodiment of the present invention, that is, the patterning of the temperature compensation layer set in the whole layer, and the fitting function of frequency Y and temperature X is Y = 0.0567X + 2534.4.

[0056] Specifically, the formula for calculating the temperature coefficient of frequency (TCF) is as follows:

[0057]

[0058] Where Δf is the frequency change when the temperature changes, ΔT is the temperature change, and f0 is the initial frequency.

[0059] Continue to refer to the table above and Figure 2 The simulation results show that without a temperature compensation layer, the TCF is -24 ppm / ℃, and the effective electromechanical coupling coefficient is 6.67%. After patterning and etching the temperature compensation layer, the TCF is -22 ppm / ℃, and the effective electromechanical coupling coefficient is 6.55%. With a full-layer temperature compensation layer, the TCF is -22 ppm / ℃, and the effective electromechanical coupling coefficient is 6.33%. Therefore, adding a 10 nm temperature compensation layer reduces the TCF from -24 ppm / ℃ to -22 ppm / ℃. Compared to a full-layer temperature compensation layer, patterning and etching the temperature compensation layer does not reduce the TCF, and the effective electromechanical coupling coefficient is higher. Therefore, the technical solution provided in this embodiment of the invention can effectively reduce the impact of the temperature compensation layer on the performance of the thin-film bulk acoustic resonator while reducing the temperature coefficient of the frequency.

[0060] It should be noted that the greater the thickness of the temperature compensation layer and the larger the area it occupies in the effective operating region, the greater its impact on the performance of the thin-film bulk acoustic wave resonator. Therefore, by adjusting the area and thickness of the temperature compensation structure to meet different temperature compensation requirements, the impact of the temperature compensation layer on the performance of the thin-film bulk acoustic wave resonator can be minimized. Furthermore, by adjusting the proportion of the area occupied in the effective operating region, the influence of the temperature compensation layer on the operating frequency of the thin-film bulk acoustic wave resonator can be effectively controlled.

[0061] The technical solution provided by this invention reduces the drift of the resonator's operating frequency caused by changes in ambient temperature by providing at least one temperature compensation layer between the substrate and the second electrode. Specifically, the temperature compensation layer includes multiple independently configured temperature compensation structures. That is, the temperature compensation layer is not a single, continuous layer, but rather multiple independently configured temperature compensation structures formed by patterning and etching a single, continuous temperature compensation layer. Thus, by controlling the patterning and etching ratio of the temperature compensation layer, i.e., by adjusting the area ratio of the temperature compensation structures occupying the effective working area, the operating frequency of the thin-film bulk acoustic resonator can be adjusted.

[0062] Optional, Figure 3 This is a schematic cross-sectional view of the second type of thin-film bulk acoustic resonator provided in an embodiment of the present invention. Figure 4 This is a schematic cross-sectional view of the third type of thin-film bulk acoustic resonator provided in an embodiment of the present invention, as shown below. Figure 1 , Figure 3 and Figure 4 As shown, a plurality of temperature compensation structures 601 are located within the first electrode 20; and / or, a plurality of temperature compensation structures 601 are located within the second electrode 40; wherein, along the thickness direction Z of the thin-film bulk acoustic resonator, the first electrode 20 includes a first surface a on the side away from the substrate 10, the second electrode includes a second surface b on the side away from the substrate 10; the temperature compensation layer 60 includes a third surface c on the side away from the substrate 10; the pattern of at least one of the first surface a and the second surface b is the same as the pattern of the third surface c.

[0063] Specifically, as one possible implementation method, please refer to [reference]. Figure 3 Multiple temperature compensation structures 601 are located within the first electrode 20. Specifically, the temperature compensation structures 601 can be located on the lower surface of the first electrode 20 or in the middle of the first electrode 20. This allows for diverse configurations of the thin-film bulk acoustic resonator and reduces temperature drift, thereby improving resonator performance. Furthermore, when multiple temperature compensation structures 601 are located within the first electrode 20, due to the thin-film deposition process, the patterns of the first surface a, the second surface b, and the third surface c are identical.

[0064] As another feasible implementation method, please refer to Figure 1 Multiple temperature compensation structures 601 are located within the second electrode 40. This allows for diverse configurations of the thin-film bulk acoustic resonator and reduces temperature drift, thereby improving resonator performance. Furthermore, when multiple temperature compensation structures 601 are located within the second electrode 40, the pattern of the second surface b is identical to the pattern of the third surface c due to the thin-film deposition process.

[0065] As another feasible implementation method, please refer to Figure 4 Multiple temperature compensation structures 601 are located within the first electrode 20 and multiple temperature compensation structures 601 are located within the second electrode 40. That is, there are two temperature compensation layers, located within the first electrode 20 and the second electrode 40 respectively. This allows for diverse configurations of the thin-film bulk acoustic resonator and further reduces temperature drift, improving resonator performance. Furthermore, when multiple temperature compensation structures 601 are located within the first electrode 20 and the second electrode 40, due to the thin-film deposition process, the patterns of the first surface a, the second surface b, and the third surface c are identical. It should be noted that the patterns on the first surface a and the second surface b are identical only at positions corresponding to the temperature compensation layer 60. In other words, along the thickness direction of the thin-film bulk acoustic resonator, the patterns of the first surface a, the second surface b, and the third surface c are identical at overlapping positions.

[0066] Furthermore, Figure 5 This is a schematic cross-sectional view of the fourth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the temperature compensation structure 601 in the second electrode 40 is located at the gap between two adjacent temperature compensation structures 601 in the first electrode 20. That is, the temperature compensation structure 601 in the second electrode 40 is staggered with the two adjacent temperature compensation structures 601 in the first electrode 20. This ensures that the upper surface of the second electrode portion 402 is flat rather than protruding, thereby reducing the thickness difference of the upper electrode of the thin-film bulk acoustic resonator, reducing the parasitic modes caused by the different frequencies due to the different thicknesses, and improving the performance of the resonator.

[0067] Understandable Figure 6 This is a schematic cross-sectional view of the fifth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention. Figure 7 for Figure 6 A top-view diagram of the corresponding temperature compensation layer in the effective working area, as shown in Figure 6. Figure 7 As shown, the independently configured temperature compensation structure 601 is located in the central region of the effective working area, while the edge region of the effective working area can be a uniformly configured temperature compensation layer. For example, the independently configured temperature compensation structure 601 can also be located in the edge region of the effective working area, or in the edge regions of the four corners of the effective working area, with the remaining positions being uniformly configured temperature compensation layers. This allows for diverse configurations of the thin-film bulk acoustic resonator and reduces temperature drift, thereby improving resonator performance.

[0068] Optional, Figure 8 This is a schematic cross-sectional view of the sixth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention. Figure 9 for Figure 8 A top-view diagram of the corresponding temperature compensation layer in the effective working area, as shown below. Figure 8 and Figure 9 As shown, at least one temperature compensation layer 60 includes a first temperature compensation layer 60-1 and a second temperature compensation layer 60-2; the first temperature compensation layer 60-1 includes a plurality of first temperature compensation structures 601-1, and the second temperature compensation layer 60-2 includes a plurality of second temperature compensation structures 601-2; along the thickness direction of the thin-film bulk acoustic resonator, the second electrode 40 includes a first electrode portion 401 and a second electrode portion 402, with a plurality of first temperature compensation structures 601-1 located within the first electrode portion 401 and a plurality of second temperature compensation structures 601-2 located within the second electrode portion 402; along the first direction (e.g. Figure 8 As shown in the V direction, there is a first gap a between two adjacent first temperature compensation structures 601-1; along the thickness direction Z of the thin film bulk acoustic resonator, the second temperature compensation structure 601-2 overlaps with the first gap a; the first direction V intersects with the thickness direction Z of the thin film bulk acoustic resonator.

[0069] Specifically, the second electrode 40 includes two temperature compensation layers 60. After a complete first temperature compensation layer 60-1 is prepared on the upper surface of the piezoelectric layer 30, the first temperature compensation layer 60-1 is patterned to form multiple independent first temperature compensation structures 601-1. Then, along the first direction V, a first gap a is included between two adjacent first temperature compensation structures 601-1. Finally, a first electrode portion 401 is deposited on the side of the first temperature compensation structure 601-1 away from the substrate 10. A full-length second temperature compensation layer 60-2 is prepared on the surface of the first electrode portion 401, and the second temperature compensation layer 60-2 is patterned to form multiple independent second temperature compensation structures 601-2. The second electrode portion 402 is deposited on the upper surface of the second temperature compensation structure 601-2, and the second temperature compensation structure 601-2 overlaps with the first gap a along the thickness direction Z of the thin-film bulk acoustic resonator. That is, the first temperature compensation structure 601-1 and the second temperature compensation structure 601-2 are staggered. This ensures that the upper surface of the second electrode portion 402 is flat rather than protruding, thereby reducing the thickness difference of the upper electrode of the thin-film bulk acoustic resonator, reducing the parasitic modes caused by the different frequencies due to the different thicknesses, and improving the performance of the resonator.

[0070] As a comparative example, along the thickness direction Z of the thin-film bulk acoustic resonator, the second temperature compensation structure 601-2 coincides with the first temperature compensation structure 601-1, that is, the second temperature compensation structure 601-2 is located directly above the first temperature compensation structure 601-1. Due to the thin-film deposition process, after the second temperature compensation structure 601-2 is prepared and the second electrode portion 402 is deposited on the second temperature compensation structure 601-2, there will be a protrusion on the upper surface of the second electrode portion 402 at the corresponding position of the second temperature compensation structure 601-2. This will increase the thickness of the resonator. Since the performance of the resonator is related to the thickness of the resonator, it will affect the performance of the resonator.

[0071] Optional, Figure 10 This is a schematic cross-sectional view of the seventh type of thin-film bulk acoustic resonator provided in the embodiments of the present invention, as shown in the figure. Figure 10 As shown, multiple temperature compensation structures 601 are located within the piezoelectric layer 30.

[0072] Specifically, multiple temperature compensation structures 601 are located within the piezoelectric layer 30. This enables diverse configurations of the thin-film bulk acoustic resonator and reduces temperature drift, thereby improving resonator performance.

[0073] For example, multiple temperature compensation structures can also be located on the upper surface of the piezoelectric layer and in contact with it. As one possible implementation, due to the thin-film deposition process, when a second electrode is deposited on the surface of the multiple temperature compensation structures, a protrusion will exist on the upper surface of the second electrode, and the protrusion on the upper surface of the second electrode corresponds to the position of the temperature compensation structure. As another possible implementation, by patterning the second electrode, the protrusion on the upper surface of the second electrode is staggered from the position of the temperature compensation structure, thus enabling diverse settings for resonance.

[0074] Optional, Figure 11 for Figure 1 A top-view diagram of the corresponding temperature compensation layer in the effective working area, as shown below. Figure 11 As shown, the distance between any two adjacent temperature compensation structures 601 is the same.

[0075] Specifically, the distance between any two adjacent temperature compensation structures 601 is the same, that is, multiple temperature compensation structures 601 are arranged periodically, forming a phononic crystal structure with the thin film bulk acoustic resonator in the horizontal direction of the temperature compensation layer, thereby suppressing transverse acoustic waves, reducing parasitic modes, and thus improving the performance of the resonator.

[0076] Optional, Figure 12 This is a schematic cross-sectional view of the eighth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention, as shown below. Figure 12As shown, multiple temperature compensation structures 601 are located within the second electrode 40; along the thickness direction Z of the thin-film bulk acoustic resonator, the second electrode 40 includes a first electrode portion 401 and a second electrode portion 402; the second electrode portion 402 includes a main body portion 4021 and multiple protrusions 4022; the protrusions 4022 are located on the side of the main body portion 4021 away from the substrate 10; along the first direction V, a second gap b is included between two adjacent protrusions 4022; along the thickness direction Z of the thin-film bulk acoustic resonator, the temperature compensation structure 601 overlaps with the second gap b; the first direction V intersects with the thickness direction Z of the thin-film bulk acoustic resonator.

[0077] Specifically, after multiple temperature compensation structures 601 are fabricated on the upper surface of the first electrode portion 401, a second electrode portion 402 is fabricated on the side of the temperature compensation structure 601 away from the substrate 10. By patterning the upper surface of the second electrode portion 402, protrusions 4022 can be formed. Along the first direction V, a second gap b is included between two adjacent protrusions 4022. In the thickness direction Z of the thin-film bulk acoustic resonator, the temperature compensation structure 601 overlaps with the second gap b. Thus, the protrusions 4022 and the temperature compensation structure 601 are staggered, thereby enabling diverse configurations of the thin-film bulk acoustic resonator.

[0078] Optional, Figure 13 This is a schematic cross-sectional view of the ninth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention, as shown below. Figure 13 As shown, multiple temperature compensation structures 601 are located within the first electrode 20 and multiple temperature compensation structures 601 are located within the second electrode 40; along the first direction V, a third gap c is included between two adjacent temperature compensation structures 601 located within the first electrode 20; along the thickness direction Z of the thin-film bulk acoustic resonator, the temperature compensation structure 601 located within the second electrode 40 overlaps with the third gap c; the first direction V intersects with the thickness direction Z of the thin-film bulk acoustic resonator.

[0079] Specifically, along the thickness direction Z of the thin-film bulk acoustic resonator, the temperature compensation structure 601 located in the second electrode 40 overlaps with the third gap c. That is to say, the orthographic projection of the temperature compensation structure 601 in the first electrode 20 onto the substrate 10 and the orthographic projection of the temperature compensation structure 601 in the second electrode 40 onto the substrate 10 do not coincide. Instead, the temperature compensation structure 601 in the first electrode 20 and the temperature compensation structure 601 in the second electrode 40 are staggered, thus enabling diverse configurations of the thin-film bulk acoustic resonator.

[0080] It should be noted that the thickness of the temperature compensation layer 60 within the first electrode 20 and the thickness of the temperature compensation layer within the second electrode 40 may be different, such as... Figure 13As shown, the thickness of the temperature compensation layer inside the second electrode 40 can be greater than the thickness of the temperature compensation layer 60 inside the first electrode 20.

[0081] Optional, continue to refer to Figure 1 The thin-film bulk acoustic resonator also includes a seed layer 70; the seed layer is located between the substrate 10 and the first electrode 20.

[0082] Specifically, the substrate 10 can be made of Si, SOI, or sapphire. By providing a seed layer 70 between the substrate 10 and the first electrode 20, the deposition of the first electrode 20 is facilitated.

[0083] Optional, Figure 14 This is a schematic cross-sectional view of the tenth type of thin-film bulk acoustic resonator provided in an embodiment of the present invention, as shown below. Figure 1 and Figure 14 As shown, the acoustic reflection layer 101 includes a cavity 1011; or, the acoustic reflection layer 101 includes a Bragg reflection layer 1012; the Bragg reflection layer 1012 includes a first acoustic impedance layer 10121 and a second acoustic impedance layer 10122, and along the thickness direction Z of the bulk acoustic wave filter, the first acoustic impedance layer 10121 and the second acoustic impedance layer 10122 are arranged alternately in sequence; wherein, the acoustic impedance of the first acoustic impedance layer 10121 is different from that of the second acoustic impedance layer 10122.

[0084] Specifically, as one possible implementation method, please refer to [reference]. Figure 1 The acoustic reflection layer 101 includes a cavity 1011. When sound waves propagate downwards, they are reflected at the interface between the cavity 1011 and the first electrode 20, thereby reducing sound leakage and improving the Q value of the resonator. It is understood that during the resonator fabrication process, to ensure the stability of the resonator, after etching the cavity 1011 in the substrate 10, sacrificial material is first filled into the cavity 1011, and chemical mechanical polishing is performed to remove excess sacrificial layer material, making the upper surface of the sacrificial layer flush with the upper surface of the substrate 10, so that the seed layer 70, the first electrode 20, the piezoelectric layer 30, and the second electrode 40 can be sequentially fabricated on the substrate 10. After the second electrode 40 is fabricated, release holes 80 are etched at corresponding positions of the piezoelectric layer 30, the first electrode 20, and the seed layer 70, and corrosive gas or liquid is introduced into the release holes 80 to erode away the sacrificial layer material, forming the cavity 1011.

[0085] As another feasible implementation method, please refer to Figure 14The acoustic reflection layer 101 includes a Bragg reflection layer 1012. The Bragg reflection layer 1012 is formed by alternating first acoustic impedance layer 10121 and second acoustic impedance layer 10122. Since the acoustic impedance of the first acoustic impedance layer 10121 is different from that of the second acoustic impedance layer 10122, the sound wave has an acoustic impedance difference when it propagates in the Bragg reflection layer 1012, which can reflect the downward leaking sound wave back to the working area, reduce sound wave leakage, and improve the Q value of the resonator.

[0086] It should be noted that continued reference is necessary. Figure 1 The thin-film bulk acoustic resonator also includes an electrode plate 50, which serves as the input and output interface for electrical signals. An AC voltage signal is applied to the electrode plate, exciting the piezoelectric layer 30 to vibrate, thereby generating sound waves. The electrode plate 50 and the piezoelectric layer 30 together form a resonant cavity, where sound waves are reflected to create resonance. The design and material selection of the electrode plate have a significant impact on the resonant frequency and Q value.

[0087] In summary, the thin-film bulk acoustic wave resonator provided in this embodiment of the invention reduces the drift of the resonator's operating frequency caused by changes in ambient temperature by providing at least one temperature compensation layer between the substrate and the second electrode. Specifically, the temperature compensation layer includes multiple independently arranged temperature compensation structures. That is, the temperature compensation layer is not a single, continuous layer, but rather multiple independently arranged temperature compensation structures formed by patterning and etching a single, continuous temperature compensation layer. Thus, by controlling the patterning and etching ratio of the temperature compensation layer, i.e., by adjusting the area ratio of the temperature compensation structures occupying the effective working area, the operating frequency of the thin-film bulk acoustic wave resonator can be adjusted.

[0088] Based on the same inventive concept, this embodiment of the invention also provides a filter, which includes the thin-film bulk acoustic resonator described in the above embodiments. Therefore, the filter provided by this embodiment of the invention also has the beneficial effects described in the above embodiments, which will not be repeated here.

[0089] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A thin film bulk acoustic resonator, characterized in that: include: A substrate; the substrate comprising a sound reflecting layer; A first electrode, located on one side of the substrate; a piezoelectric layer, located on a side of the first electrode away from the substrate; A second electrode is located on a side of the piezoelectric layer away from the substrate; Along the thickness direction of the thin film bulk acoustic wave resonator, the first electrode, the piezoelectric layer and the second electrode overlap in an effective working area; At least one temperature compensation layer is located between the substrate and the second electrode, and along the thickness direction of the thin film bulk acoustic wave resonator, the temperature compensation layer overlaps with the effective working area; the temperature compensation layer includes a plurality of independently arranged temperature compensation structures.

2. The thin film bulk acoustic resonator according to claim 1, characterized in that: A plurality of the temperature compensation structures are located in the first electrode; and / or, a plurality of the temperature compensation structures are located in the second electrode; Among them, along the thickness direction of the thin film bulk acoustic wave resonator, the first electrode includes a first surface away from the side of the substrate, and the second electrode includes a second surface away from the side of the substrate; the temperature compensation layer includes a third surface away from the side of the substrate; the pattern of at least one of the first surface and the second surface is the same as the pattern of the third surface.

3. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The at least one temperature compensation layer includes a first temperature compensation layer and a second temperature compensation layer; the first temperature compensation layer includes a plurality of first temperature compensation structures, and the second temperature compensation layer includes a plurality of second temperature compensation structures; Along the thickness direction of the thin film bulk acoustic wave resonator, the second electrode includes a first electrode section and a second electrode section; A plurality of the first temperature compensation structures are located in the first electrode subdivision, and a plurality of the second temperature compensation structures are located in the second electrode subdivision; Along the first direction, a first gap is provided between two adjacent first temperature compensation structures; along the thickness direction of the thin film bulk acoustic wave resonator, the second temperature compensation structure overlaps with the first gap; and the first direction intersects with the thickness direction of the thin film bulk acoustic wave resonator.

4. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: A plurality of the temperature compensation structures are located within the piezoelectric layer.

5. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The distance between any two adjacent temperature compensation structures is the same.

6. The thin film bulk acoustic wave resonator according to claim 2, characterized in that: A plurality of the temperature compensation structures are located in the second electrode; Along the thickness direction of the thin film bulk acoustic wave resonator, the second electrode includes a first electrode section and a second electrode section; the second electrode section includes a main body and a plurality of protrusions; the protrusions are located on a side of the main body away from the substrate; Along the first direction, a second gap is provided between two adjacent protrusions; along the thickness direction of the FBAR, the temperature compensation structure overlaps with the second gap; and the first direction intersects with the thickness direction of the FBAR.

7. The thin film bulk acoustic wave resonator according to claim 2, characterized in that: A plurality of the temperature compensation structures are located in the first electrode and a plurality of the temperature compensation structures are located in the second electrode; Along the first direction, a third gap is included between two adjacent temperature compensation structures located in the first electrode; along the thickness direction of the thin film bulk acoustic wave resonator, the temperature compensation structure located in the second electrode overlaps with the third gap; the first direction intersects with the thickness direction of the thin film bulk acoustic wave resonator.

8. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The thin film bulk acoustic wave resonator further includes a seed layer; The seed layer is located between the substrate and the first electrode.

9. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The sound reflecting layer includes a cavity; Alternatively, the acoustic reflection layer comprises a Bragg reflection layer; the Bragg reflection layer comprises a first acoustic impedance layer and a second acoustic impedance layer, and along the thickness direction of the bulk acoustic wave filter, the first acoustic impedance layer and the second acoustic impedance layer are alternately arranged in sequence; The acoustic impedance of the first acoustic impedance layer is different from the acoustic impedance of the second acoustic impedance layer.

10. A filter, characterized in that: A thin film bulk acoustic wave resonator comprising any one of claims 1 to 9.

Images