Acoustic resonator, filter, communication device and method of manufacturing the same

Abstract

Embodiments of the present application provide an acoustic resonator, a filter, a communication device and a manufacturing method thereof, wherein the acoustic resonator comprises: a substrate; a recess formed in an epitaxial layer on or in the substrate, the recess having an open profile on the surface of the substrate or the epitaxial layer; a lower electrode in contact with the plane of the open profile; a piezoelectric layer formed on the lower electrode; and an upper electrode formed on the piezoelectric layer; wherein the lower electrode profile of the lower electrode has at least three intersection points with the open profile, and the distance from the intersection point of the first straight line and the first part profile to the centroid is greater than the distance from the intersection point of the first straight line and the second part profile to the centroid.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, specifically to an acoustic resonator, a filter, a communication device, and a method for manufacturing the same. Background Technology

[0002] In the field of semiconductor manufacturing technology, there are thin-film bulk acoustic resonators (FBARs) and surface acoustic wave resonators (SAWs), among which FBARs are more suitable for portable communication devices and are compatible with standard integrated manufacturing technologies. For example... Figure 1 As shown, where Figure 1 It is along Figure 3 The cross-sectional view of AA in the figure shows that a typical thin-film bulk acoustic resonator includes a substrate 101, a cavity 102 formed in the substrate 101, a lower electrode 103, an upper electrode 105, and a piezoelectric layer 104 sandwiched between the upper and lower electrodes. The upper and lower electrodes and the piezoelectric layer form a "sandwich" structure. When an input electrical signal is applied between the upper and lower electrodes, the inverse piezoelectric effect causes the piezoelectric layer to mechanically expand or contract due to the polarization of the piezoelectric material. As the input electrical signal changes over time, the expansion and contraction of the piezoelectric layer generates sound waves that propagate in various directions and are converted into electrical signals through the piezoelectric effect.

[0003] In existing technologies such as Figure 2 As shown, in the "sandwich" structure, the lower electrode 103 completely covers the cavity 102, resulting in a large contact area between the sandwich structure and the substrate outside the cavity 102 of the thin-film bulk acoustic resonator (FBAR). During operation, a considerable amount of energy leaks outward along the boundary overlap, thus affecting the quality factor and performance of the product.

[0004] Furthermore, in order to release the sacrificial layer to form cavity 102, and to reduce the impact of the release hole on the sandwich structure, the release hole 106 needs to be positioned slightly off-center from the cavity, such as... Figure 3 As shown, an additional release channel 107 is needed to extend the release hole 106 into the cavity, which increases the difficulty of the process and results in incomplete release of material from the cavity. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide an acoustic resonator, a filter, a communication device and a method for manufacturing the same, to solve the technical problems of difficulty in forming cavities and difficulty in completely releasing cavity materials in the prior art.

[0006] According to a first aspect, embodiments of the present invention provide an acoustic resonator, characterized in that it comprises: a substrate; a recess formed within the substrate or an epitaxial layer on the substrate, the recess having an opening profile on the surface of the substrate or the surface of the epitaxial layer; a lower electrode in contact with a plane containing the opening profile; a piezoelectric layer formed on the lower electrode; and an upper electrode formed on the piezoelectric layer; wherein the lower electrode profile of the lower electrode intersects the opening profile at at least three points, the lower electrode profile has a first partial profile between a pair of adjacent intersection points, the opening profile has a second partial profile between the pair of adjacent intersection points, any point on the first partial profile and the centroid of the overlapping region of the lower electrode profile and the opening profile form a first straight line, the first straight line passing through the first partial profile and the second partial profile, the distance from the intersection point of the first straight line and the first partial profile to the centroid is greater than the distance from the intersection point of the first straight line and the second partial profile to the centroid.

[0007] Optionally, the lower electrode profile has a third partial profile between another pair of adjacent intersection points, and the opening profile has a fourth partial profile between another pair of adjacent intersection points. Any point on the third partial profile is connected to the centroid of the overlapping area of ​​the lower electrode profile and the opening profile by a second straight line. The second straight line passes through the third partial profile and the fourth partial profile. The distance from the intersection of the second straight line and the third partial profile to the centroid is less than the distance from the intersection of the second straight line and the fourth partial profile to the centroid.

[0008] Optionally, the third portion of the contour has a release hole on the outer side and the fourth portion of the contour has a release hole on the inner side.

[0009] Optionally, at least one of the two pairs of adjacent intersections is different from the other pair of adjacent intersections.

[0010] Optionally, the lower electrode profile and the opening profile are polygonal, circular, or elliptical.

[0011] Optionally, the polygon is a triangle, quadrilateral, hexagon, or octagon.

[0012] Optionally, the geometric centers of the lower electrode profile and the opening profile coincide.

[0013] Optionally, the lower electrode profile is rotated and offset relative to the opening profile by a predetermined angle.

[0014] Optionally, the lower electrode includes at least two first conductive layers, wherein the acoustic impedance of the first conductive layer farther from the piezoelectric layer is greater than the acoustic impedance of the first conductive layer closer to the piezoelectric layer.

[0015] Optionally, the upper electrode includes at least two second conductive layers, wherein the acoustic impedance of the second conductive layer farther from the piezoelectric layer is greater than the acoustic impedance of the second conductive layer closer to the piezoelectric layer.

[0016] Optionally, the lower electrode is made of two different materials, wherein the first portion of the lower electrode located within the opening profile is made of a first material; the second portion of the lower electrode located outside the opening profile is made of a second material; the first material and the second material have different acoustic impedances; or the second material has a different temperature coefficient than the piezoelectric layer.

[0017] According to a second aspect, embodiments of the present invention provide a method for manufacturing an acoustic resonator, comprising: forming a recess in a substrate or an epitaxial layer on the substrate, the recess having an opening profile on the surface of the substrate or the surface of the epitaxial layer; forming a sacrificial layer in the recess and planarizing the sacrificial layer; forming a lower electrode on the sacrificial layer, the lower electrode contacting a plane containing the opening profile; forming a piezoelectric layer on the lower electrode; forming an upper electrode on the piezoelectric layer; wherein the lower electrode profile of the lower electrode and the opening profile have at least three intersection points, the lower electrode profile has a first partial profile between a pair of adjacent intersection points, the opening profile has a second partial profile between the pair of adjacent intersection points, any point on the first partial profile and the centroid of the overlapping region of the lower electrode profile and the opening profile form a first straight line, the first straight line passing through the first partial profile and the second partial profile, the distance from the intersection point of the first straight line and the first partial profile to the centroid is greater than the distance from the intersection point of the first straight line and the second partial profile to the centroid.

[0018] Optionally, the lower electrode profile has a third partial profile between another pair of adjacent intersection points, and the opening profile has a fourth partial profile between another pair of adjacent intersection points. Any point on the third partial profile is connected to the centroid of the overlapping area of ​​the lower electrode profile and the opening profile by a second straight line. The second straight line passes through the third partial profile and the fourth partial profile. The distance from the intersection of the second straight line and the third partial profile to the centroid is less than the distance from the intersection of the second straight line and the fourth partial profile to the centroid.

[0019] Optionally, the method further includes forming a release hole on the sacrificial layer outside the third portion contour and inside the fourth portion contour, or on the piezoelectric layer and / or the upper electrode above the sacrificial layer at that location, to remove the sacrificial layer through the release hole.

[0020] Optionally, at least one of the two pairs of adjacent intersections is different from the other pair of adjacent intersections.

[0021] According to a third aspect, embodiments of the present invention provide a filter comprising at least one acoustic resonator as described in any one of the first aspects above.

[0022] According to a fourth aspect, embodiments of the present invention provide a method for manufacturing a filter, the filter comprising at least one acoustic resonator, wherein the at least one acoustic resonator is manufactured using the method for manufacturing an acoustic resonator as described in any one of the second aspects above.

[0023] According to a fifth aspect, embodiments of the present invention provide a communication device including the filter described in the third aspect above.

[0024] In the acoustic resonator of this embodiment, since the distance from the intersection of the first straight line and the first part of the lower electrode contour to the centroid is greater than the distance from the intersection of the first straight line and the second part of the opening contour to the centroid, a portion of the lower electrode can contact the plane where the opening contour is located, so that the acoustic resonator can be more stably mounted on the recess.

[0025] Furthermore, in the acoustic resonator of this embodiment, since the distance from the intersection of the second straight line and the third part of the lower electrode contour to the centroid is less than the distance from the intersection of the second straight line and the fourth part of the opening contour to the centroid, a portion of the recessed area can be exposed from the lower electrode. Therefore, a release hole can be provided outside the third part of the contour and inside the fourth part of the contour, eliminating the need for an additional release channel. This reduces the possibility of incomplete release of the cavity filling material, lowers the manufacturing difficulty, and saves economic costs. More importantly, it can reduce the lateral and longitudinal energy leakage of the resonator or filter, improve the product's quality factor, and improve the electromechanical coupling coefficient Kt value. Attached Figure Description

[0026] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0027] Figures 1 to 3 A schematic diagram of an existing acoustic resonator is shown.

[0028] Figures 4 to 6 A schematic diagram of the structure of a first embodiment of the acoustic resonator of the present invention is shown;

[0029] Figure 7 A schematic diagram showing a variation of the lower electrode profile and opening profile of an acoustic resonator according to an embodiment of the present invention is provided.

[0030] Figure 8 A schematic diagram of another variation of the lower electrode profile and opening profile of the acoustic resonator according to an embodiment of the present invention is shown;

[0031] Figures 9A to 9H The diagram shows a structural schematic of each step in the manufacturing method of the acoustic resonator according to an embodiment of the present invention;

[0032] Figure 10 A schematic diagram of a second embodiment of the acoustic resonator of the present invention is shown;

[0033] Figure 11 A schematic diagram of a third embodiment of the acoustic resonator of the present invention is shown. Detailed Implementation

[0034] Exemplary aspects of this disclosure will be described below with reference to the accompanying drawings. For clarity and brevity, not all features implementing this disclosure are described in the specification. However, it should be understood that many disclosure-specific decisions can be made in developing any such implementation of this disclosure to achieve the developer's specific goals, and these decisions may vary depending on the specific implementation of this disclosure.

[0035] It should also be noted that, in order to avoid obscuring the contents of this disclosure with unnecessary details, only the device structure closely related to the solution according to this disclosure is shown in the accompanying drawings, while other details that are not closely related to this disclosure are omitted.

[0036] It should be understood that this disclosure is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, features may be substituted or borrowed between different embodiments where feasible, and one or more features may be omitted in one embodiment.

[0037] First Implementation Plan

[0038] Figure 4-6 A first embodiment of the acoustic resonator of the present invention is shown, wherein... Figure 4 This is a top view of the structure of the acoustic resonator in this embodiment. Figure 5 It is along Figure 4 A sectional view of section BB in the middle.

[0039] The acoustic resonator may include a substrate 201, which may be formed from materials compatible with the semiconductor process, such as silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), glass, sapphire, alumina, or SiC. A recess 202 is formed within the substrate 201, which may be formed, for example, by etching. Those skilled in the art will understand that, as another alternative embodiment, the recess 202 may also be formed within an epitaxial layer on the substrate 201. The recess 202 has an opening profile 212 on the surface of the substrate 201 or the surface of the epitaxial layer. The acoustic resonator includes a sandwich structure formed by a lower electrode 203, a piezoelectric layer 204, and an upper electrode 205. The lower electrode 203 of the acoustic resonator is in contact with the plane containing the opening profile 212, i.e., the lower electrode 203 is in contact with the upper surface of the substrate 201 or the upper surface of the epitaxial layer on the substrate 201. Figure 5 In the example, the plane is the upper surface of the substrate 201, and the lower electrode of the acoustic resonator and the recess 202 form a cavity.

[0040] More specifically, such as Figure 6 As shown, Figure 6 The diagram shows a lower electrode profile 213 and an opening profile 212. In this embodiment, the lower electrode profile 213 and the opening profile 212 have eight intersection points, which are labeled J1 to J8 in chronological order. The lower electrode profile 213 has a first partial profile L1 between a pair of adjacent intersection points (taking adjacent intersection points J8 and J1 as an example). The opening profile 212 has a second partial profile L2 between the same adjacent intersection points J8 and J1. Any point on the first partial profile L1 and the centroid O of the overlapping area of ​​the lower electrode profile 213 and the opening profile 212 form a first straight line Z1. The first straight line Z1 passes through the first partial profile L1 and the second partial profile L2. The distance from the intersection point of the first straight line Z1 and the first partial profile L1 to the centroid O is greater than the distance from the intersection point of the first straight line Z1 and the second partial profile L2 to the centroid O. Similarly, the profile of the lower electrode profile 213 between adjacent intersection points J2 and J3, adjacent intersection points J4 and J5, and adjacent intersection points J6 and J7 can also be the first part profile L1. Correspondingly, the profile of the opening profile 212 between adjacent intersection points J2 and J3, adjacent intersection points J4 and J5, and adjacent intersection points J6 and J7 can also be the second part profile L2. Likewise, the distance from the intersection of the first straight line Z1 and the first part profile L1 to the centroid O is greater than the distance from the intersection of the first straight line Z1 and the second part profile L2 to the centroid O.

[0041] Because the distance from the intersection point of the first straight line Z1 and the first portion of the profile L1 in the lower electrode profile 213 to the centroid O is greater than the distance from the intersection point of the first straight line Z1 and the second portion of the profile L2 in the opening profile 212 to the centroid O, a portion of the lower electrode 203 can contact the plane where the opening profile 212 is located, for example, it can contact the upper surface of the substrate 201 or the upper surface of the epitaxial layer on the substrate 201. The more intersection points between the lower electrode profile 213 and the opening profile 212, the more stably the acoustic resonator can be mounted on the recess 202. In order for the acoustic resonator to be mounted on the recess 202, the lower electrode profile 213 and the opening profile 212 need at least three intersection points.

[0042] Furthermore, the lower electrode profile 213 has a third partial profile L3 between another pair of adjacent intersection points (taking adjacent intersection points J1 and J2 as an example), and the opening profile 212 has a fourth partial profile L4 between the same adjacent intersection points J1 and J2. Any point on the third partial profile L3 and the centroid O of the overlapping area of ​​the lower electrode profile 213 and the opening profile 212 form a second straight line Z2. The second straight line Z2 passes through the third partial profile L3 and the fourth partial profile L4. The distance from the intersection of the second straight line Z2 and the third partial profile L3 to the centroid O is less than the distance from the intersection of the second straight line Z2 and the fourth partial profile L4 to the centroid O. Similarly, the profile of the lower electrode profile 213 between adjacent intersection points J3 and J4, adjacent intersection points J5 and J6, and adjacent intersection points J7 and J8 can also be the third part profile L3. Correspondingly, the profile of the opening profile 212 between adjacent intersection points J3 and J4, adjacent intersection points J5 and J6, and adjacent intersection points J7 and J8 can also be the fourth part profile L4. Likewise, the distance from the intersection point of the second straight line Z2 and the third part profile L3 to the centroid O is less than the distance from the intersection point of the second straight line Z2 and the fourth part profile L4 to the centroid O.

[0043] Because the distance from the intersection of the second straight line Z2 and the third part of the lower electrode contour 213 to the centroid O is less than the distance from the intersection of the second straight line Z2 and the fourth part of the opening contour 212 to the centroid O, a portion of the recessed portion 202 can be exposed from the lower electrode 203. Therefore, a release hole 206 can be provided outside the third part of the contour L3 and inside the fourth part of the contour L4, eliminating the need for an additional release channel. This reduces the possibility of incomplete release of the cavity filling material, lowers the manufacturing difficulty, and saves economic costs. More importantly, it reduces the lateral and longitudinal energy leakage of the resonator or filter, improves the product's quality factor, and enhances the electromechanical coupling coefficient Kt value.

[0044] Furthermore, in this embodiment of the acoustic resonator, a piezoelectric layer 204 is formed on the lower electrode 203, and the piezoelectric layer 204 may also extend and cover the lower electrode 203, the cavity 202, and the substrate 201. An upper electrode 205 is formed on the piezoelectric layer 204. The lower electrode 203 and the upper electrode 205 can be a single layer or multiple layers, and the upper / lower electrodes can be formed of one or more conductive materials, such as various metals compatible with semiconductor processes including tungsten (W), molybdenum (Mo), iridium (Ir), aluminum (Al), platinum (Pt), ruthenium (Ru), niobium (Nb), or hafnium (Hf). The materials of the upper electrode and the lower electrode can be the same or different. The piezoelectric layer 204 can be formed of any piezoelectric material compatible with semiconductor processes, such as aluminum nitride (AlN), doped aluminum nitride, or zirconate titanate (PZT). The overlapping portion of the upper electrode, piezoelectric layer, and lower electrode above the acoustic wave reflection region constitutes the sandwich structure of the acoustic resonator.

[0045] Furthermore, a mass load layer can be adaptively formed on the upper electrode 205, and a protective layer can also be formed on the mass load layer to protect the acoustic resonator. Those skilled in the art should understand that a bonding layer and a cap wafer can also be formed on the acoustic resonator. By bonding the bonding layer and the cap wafer and thinning them, a device package is formed. The bonding layer material can be, for example, Au, or other suitable bonding materials, which will not be elaborated here.

[0046] exist Figure 6 In the example, the lower electrode profile 213 is an irregular quadrilateral, and the opening profile 212 is a circle. Those skilled in the art should understand that other regular or irregular polygons are also feasible, such as triangles, quadrilaterals, hexagons, or octagons, or circles or ellipses. Figure 7 As shown, the lower electrode profile 213 and the opening profile 212 have three intersection points. Based on the principle that three points determine a plane, if the number of intersection points is less than three, the acoustic resonator cannot be stably mounted on the recess.

[0047] Furthermore, in the acoustic resonator of this embodiment of the invention, such as Figure 8 As shown, the lower electrode profile 213 and the opening profile 212 can also be elliptical.

[0048] like Figures 9A to 9H As shown, the manufacturing method of the acoustic resonator in this embodiment of the invention may include the following steps:

[0049] S101. A recess 202 is formed in the substrate 201, and the recess 202 has an opening profile 212 on the substrate surface.

[0050] Those skilled in the art will understand that the recess 202 can also be formed within an epitaxial layer on the substrate, thus giving the recess an opening profile on the surface of the epitaxial layer on the substrate. The recess 202 can be formed through a process of applying photoresist, exposure, and etching. The opening profile can be various regular or irregular patterns.

[0051] S102. A sacrificial layer 207 is formed in the recess 202, and the sacrificial layer 207 is planarized.

[0052] The sacrificial layer can be selected from thin film materials such as phosphosilicate glass, silicon dioxide, and amorphous silicon, which are compatible with the deposition temperature of subsequent thin films, do not contaminate the process system, and have good etching selectivity and chemical polishing properties. Then, the sacrificial layer outside the cavity is removed by planarization processes such as CMP, allowing the sacrificial layer to fill the recess 202. Figure 9A and 9B As shown, where Figure 9B yes Figure 9A Top view.

[0053] S103. A lower electrode 203 is formed on the sacrificial layer 207, and the lower electrode 203 is in contact with the plane containing the opening profile. For example... Figure 9C-9D As shown.

[0054] S104. A piezoelectric layer 204 is formed on the lower electrode 203; an upper electrode 205 is formed on the piezoelectric layer 204. For example... Figure 9E As shown.

[0055] Similarly, the lower electrode contour 213 and the opening contour 212 have at least three intersection points. The distance from the intersection point of the first straight line Z1 and the first part of the contour L1 in the lower electrode contour 213 to the centroid O is greater than the distance from the intersection point of the first straight line Z1 and the second part of the contour L2 in the opening contour 212 to the centroid O; and the distance from the intersection point of the second straight line Z2 and the third part of the contour L3 in the lower electrode contour 213 to the centroid O is less than the distance from the intersection point of the second straight line Z2 and the fourth part of the contour L4 in the opening contour 212 to the centroid O. It should be understood that the material of the lower electrode layer is not limited to the electrode materials described above; any electrode material with high acoustic impedance and high sound velocity is acceptable. The lower electrode layer 203 can be formed by coating photoresist, exposure, and etching. The projection shape of the lower electrode 203 onto the upper surface of the substrate 201 can be an irregular shape, or a regular polygon or ellipse such as a triangle, rectangle, hexagon, or octagon.

[0056] Further, a piezoelectric layer 204 is deposited on the lower electrode 203. The piezoelectric layer material can be selected to meet the bandwidth requirements of wireless mobile communication signal transmission and reception. As mentioned above, materials compatible with the semiconductor process, such as aluminum nitride (AlN) or zirconate titanate (PZT), are preferred. An upper electrode 205 is deposited on the piezoelectric layer 204.

[0057] Furthermore, the method for manufacturing the acoustic resonator according to embodiments of the present invention may also include the following steps:

[0058] S105. Photoresist is coated on the upper electrode 205, and the upper electrode layer 205 is exposed, developed, and etched to achieve the fabrication of the upper electrode. Figure 9F As shown. It is understood that the lower electrode layer may not be etched in step S103, but the piezoelectric layer and the lower electrode layer may be etched simultaneously when the upper electrode is etched. The contour shape of the upper electrode on the projection plane may be the same as the contour shape of the lower electrode on the projection plane.

[0059] S106. A release hole 206 is formed on the sacrificial layer 207 outside the third portion contour and inside the fourth portion contour, or on the piezoelectric layer and / or the upper electrode above the sacrificial layer at that location, to remove the sacrificial layer 207 through the release hole 268, as shown. Figure 9G As shown.

[0060] It is understandable that when etching the upper electrode layer and the piezoelectric layer and the lower electrode layer at the same time, the release hole 206 can be formed by etching at the location of the sacrificial layer 207 that is not covered by the lower electrode 203.

[0061] S107. The sacrificial layer 207 is removed through the release hole 206 to form a cavity 202. Specifically, depending on the material of the sacrificial layer, oxidation or selective etching methods can be used to remove the sacrificial layer 207.

[0062] S108. Photoresist is coated on the substrate after the sacrificial layer has been removed. After exposure and development, a bonding material, such as Au, is deposited. Then, through a lift-off process, the photoresist and Au on other areas are peeled off to form a bonding layer 208. The bonding layer 208 is then bonded to the cap wafer 209, as shown below. Figure 9H As shown.

[0063] S109. The bonded device is thinned and ground to form a package.

[0064] Second Implementation Plan

[0065] Figure 10 An acoustic resonator according to another embodiment of the present invention is shown. Components identical to those in the first embodiment can be referred to the relevant description above and will not be repeated here.

[0066] The difference between this implementation plan and the first implementation plan is that, Figure 10As shown, the lower electrode of this embodiment includes two first conductive layers 203a and 203b, wherein the acoustic impedance of the first conductive layer 203a, which is farther away from the piezoelectric layer 204, is greater than the acoustic impedance of the first conductive layer 203b, which is closer to the piezoelectric layer 204. Furthermore, the upper electrode includes two second conductive layers 205a and 205b, wherein the acoustic impedance of the second conductive layer 205b, which is farther away from the piezoelectric layer 204, is greater than the acoustic impedance of the second conductive layer 205a, which is closer to the piezoelectric layer 204.

[0067] Although Figure 10 The example only shows two first conductive layers and two second conductive layers. Those skilled in the art should understand that the upper and lower electrodes can be composed of more conductive layers. The acoustic impedance of the first conductive layer farther from the piezoelectric layer is greater than that of the first conductive layer closer to the piezoelectric layer, and the acoustic impedance of the second conductive layer farther from the piezoelectric layer is greater than that of the second conductive layer closer to the piezoelectric layer. That is, for several first conductive layers, the acoustic impedance of the first conductive layer gradually increases with increasing distance from the piezoelectric layer 204; and for several second conductive layers, the acoustic impedance of the second conductive layer gradually increases with increasing distance from the piezoelectric layer 204.

[0068] In this embodiment, by employing multiple conductive layers in at least one of the upper and lower electrodes, and by increasing the acoustic impedance of each conductive layer with increasing distance from the piezoelectric layer, the fractional frequency separation (FFS) of the resonator can be increased, thereby increasing the parallel resistance (R) of the resonator. p The quality (Q) factor is used to improve the performance of the resonator.

[0069] Third Implementation Plan

[0070] Figure 11 An acoustic resonator according to another embodiment of the present invention is shown. Components identical to those in the first embodiment can be referred to the relevant description above and will not be repeated here.

[0071] The difference between this implementation plan and the first implementation plan is that, Figure 11As shown, the lower electrode of this embodiment is made of two different materials. The first portion 203c of the lower electrode located within the opening contour 212 is made of the first material, and the second portion 203d of the lower electrode located outside the opening contour 212 (represented by the shaded area in the figure) is made of the second material. Furthermore, the second material has a positive temperature coefficient; that is, the second portion 203d of the lower electrode is made of a second material with a positive temperature coefficient. This is because the piezoelectric layer 204 of the resonator is typically formed of piezoelectric materials such as aluminum nitride (AlN), doped aluminum nitride, or zirconate titanate (PZT), and piezoelectric materials typically exhibit a negative temperature coefficient. By making the second portion 203d of the lower electrode located outside the opening contour 212 of the second material with a positive temperature coefficient, this embodiment can at least partially offset the frequency response shift caused by piezoelectric materials with negative temperature coefficients, thereby achieving a temperature-compensated frequency response and improving the quality (Q) factor of the resonator, thus enhancing the resonator's performance.

[0072] Fourth Implementation Plan

[0073] This embodiment provides a filter that may include at least one acoustic resonator as described in any of the first to third embodiments above.

[0074] This embodiment also provides a method for manufacturing a filter, wherein at least one acoustic resonator is manufactured using the method for manufacturing an acoustic resonator described in any of the first to third embodiments above.

[0075] The specific details of the filter and its manufacturing method can be understood by referring to the relevant descriptions and effects in the first to third implementation schemes above, and will not be repeated here.

[0076] Fifth Implementation Plan

[0077] This embodiment provides a communication device, such as a mobile phone, a personal digital assistant (PDA), a video game device, or other portable communication device, which may include the filter described in the fourth embodiment above.

[0078] The foregoing description of this disclosure in conjunction with specific implementation schemes is exemplary and not intended to limit the scope of protection of this disclosure. Those skilled in the art can make various modifications and variations to this disclosure based on its spirit and principles, and such modifications and variations are also within the scope of this disclosure.

Claims

1. An acoustic resonator, characterized in that, include: Substrate; A recess is formed within the substrate or in an epitaxial layer on the substrate, the recess having an opening profile on the surface of the substrate or the surface of the epitaxial layer; The lower electrode is in contact with the plane containing the opening profile; A piezoelectric layer is formed on the lower electrode; The upper electrode is formed on the piezoelectric layer; wherein The lower electrode profile of the lower electrode and the opening profile have at least three intersection points. The lower electrode profile has a first partial profile between a pair of adjacent intersection points, and the opening profile has a second partial profile between a pair of adjacent intersection points. A first straight line is formed by connecting any point on the first partial profile with the centroid of the overlapping area of ​​the lower electrode profile and the opening profile. The first straight line passes through the first partial profile and the second partial profile. The distance from the intersection point of the first straight line and the first partial profile to the centroid is greater than the distance from the intersection point of the first straight line and the second partial profile to the centroid.

2. The acoustic resonator according to claim 1, characterized in that, The lower electrode profile has a third partial profile between another pair of adjacent intersection points, and the opening profile has a fourth partial profile between another pair of adjacent intersection points. Any point on the third partial profile is connected to the centroid of the overlapping area of ​​the lower electrode profile and the opening profile by a second straight line. The second straight line passes through the third partial profile and the fourth partial profile. The distance from the intersection of the second straight line and the third partial profile to the centroid is less than the distance from the intersection of the second straight line and the fourth partial profile to the centroid.

3. The acoustic resonator according to claim 2, characterized in that, The third part of the contour has a release hole on its outer side and the fourth part of the contour has a release hole on its inner side.

4. The acoustic resonator according to claim 2, characterized in that, The pair of adjacent intersection points has at least one different intersection point from the other pair of adjacent intersection points.

5. The acoustic resonator according to claim 1, characterized in that, The lower electrode profile and the opening profile are polygonal, circular, or elliptical.

6. The acoustic resonator according to claim 5, characterized in that, The polygon is a triangle, quadrilateral, hexagon, or octagon.

7. The acoustic resonator according to claim 1, characterized in that, The geometric centers of the lower electrode profile and the opening profile coincide.

8. The acoustic resonator according to claim 7, characterized in that, The lower electrode profile is rotated and offset by a predetermined angle relative to the opening profile.

9. The acoustic resonator according to claim 1, characterized in that, The lower electrode includes at least two first conductive layers, wherein the acoustic impedance of the first conductive layer farther from the piezoelectric layer is greater than the acoustic impedance of the first conductive layer closer to the piezoelectric layer.

10. The acoustic resonator according to claim 1, characterized in that, The upper electrode includes at least two second conductive layers, wherein the acoustic impedance of the second conductive layer farther away from the piezoelectric layer is greater than the acoustic impedance of the second conductive layer closer to the piezoelectric layer.

11. The acoustic resonator according to any one of claims 1-10, characterized in that, The lower electrode is made of two different materials, wherein the first portion of the lower electrode located within the opening profile is made of the first material; The second portion of the lower electrode located outside the opening profile is made of a second material; The first material and the second material have different acoustic impedances; or The second material has a different temperature coefficient than the piezoelectric layer.

12. A method for manufacturing an acoustic resonator, characterized in that, include: A recess is formed in the substrate or in the epitaxial layer on the substrate, the recess having an opening profile on the surface of the substrate or the surface of the epitaxial layer; A sacrificial layer is formed within the recess, and the sacrificial layer is planarized; A lower electrode is formed on the sacrificial layer, and the lower electrode is in contact with the plane containing the opening profile; A piezoelectric layer is formed on the lower electrode; An upper electrode is formed on the piezoelectric layer; in The lower electrode profile of the lower electrode and the opening profile have at least three intersection points. The lower electrode profile has a first partial profile between a pair of adjacent intersection points, and the opening profile has a second partial profile between a pair of adjacent intersection points. A first straight line is formed by connecting any point on the first partial profile with the centroid of the overlapping area of ​​the lower electrode profile and the opening profile. The first straight line passes through the first partial profile and the second partial profile. The distance from the intersection point of the first straight line and the first partial profile to the centroid is greater than the distance from the intersection point of the first straight line and the second partial profile to the centroid.

13. The manufacturing method according to claim 12, characterized in that, The lower electrode profile has a third partial profile between another pair of adjacent intersection points, and the opening profile has a fourth partial profile between another pair of adjacent intersection points. Any point on the third partial profile is connected to the centroid of the overlapping area of ​​the lower electrode profile and the opening profile by a second straight line. The second straight line passes through the third partial profile and the fourth partial profile. The distance from the intersection of the second straight line and the third partial profile to the centroid is less than the distance from the intersection of the second straight line and the fourth partial profile to the centroid.

14. The manufacturing method according to claim 13, characterized in that, The method further includes: A release hole is formed on the sacrificial layer outside the third portion contour and inside the fourth portion contour, or on the piezoelectric layer and / or the upper electrode above the sacrificial layer outside the third portion contour and inside the fourth portion contour, to remove the sacrificial layer through the release hole.

15. The manufacturing method according to claim 13, characterized in that, The pair of adjacent intersection points has at least one different intersection point from the other pair of adjacent intersection points.

16. A filter, characterized in that, It includes at least one acoustic resonator according to any one of claims 1-11.

17. A method for manufacturing a filter, the filter comprising at least one acoustic resonator, characterized in that, The at least one acoustic resonator is manufactured using the method for manufacturing an acoustic resonator according to any one of claims 12-15.

18. A communication device, characterized in that, Includes the filter as described in claim 16.

Images