CN111010118B

CN111010118B - Bulk acoustic resonator with cavity support structure, filter and electronic device

Info

Publication number: CN111010118B
Application number: CN201910751463.4A
Authority: CN
Inventors: 张孟伦; 庞慰; 杨清瑞; 张全德; 徐利军
Original assignee: Tianjin University; ROFS Microsystem Tianjin Co Ltd
Current assignee: Tianjin University; ROFS Microsystem Tianjin Co Ltd
Priority date: 2019-08-15
Filing date: 2019-08-15
Publication date: 2023-10-27
Anticipated expiration: 2039-08-15
Also published as: CN111010118A; WO2021027320A1

Abstract

The invention relates to a bulk acoustic wave resonator comprising: a substrate; an acoustic mirror cavity; a bottom electrode; a top electrode; a piezoelectric layer, wherein: the overlapped area of the acoustic mirror cavity, the bottom electrode, the piezoelectric layer and the top electrode in the thickness direction of the substrate is an effective area of the resonator; the acoustic mirror cavity is internally provided with a supporting structure, the lower end of the supporting structure is arranged at the bottom of the acoustic mirror cavity, the upper end of the supporting structure is connected or contacted with the lower side of the effective area in a high-temperature area of the effective area, the high-temperature area is an area taking the mass center of the effective area as a circle center and r as a radius, the radius r is 50% of the radius of an equivalent circle of the effective area where the high-temperature area is located, and the equivalent circle is: a circle having the center of mass of the effective region as a center and an area of the circle being equal to an area of the effective region. The invention also relates to a filter and an electronic device.

Description

Bulk acoustic resonator with cavity support structure, filter and electronic device

Technical Field

Embodiments of the present invention relate to the field of semiconductors, and more particularly, to a bulk acoustic wave resonator, a filter, and an electronic device having one of the above components.

Background

The thin film bulk acoustic resonator (Film Bulk Acoustic Resonator, abbreviated as FBAR, also called BAW) plays an important role as a MEMS chip in the communication field, and the FBAR filter has excellent characteristics of small size (μm level), high resonant frequency (GHz), high quality factor (1000), large power capacity, good roll-off effect, etc., is gradually replacing the conventional Surface Acoustic Wave (SAW) filter and ceramic filter, plays a great role in the radio frequency field of wireless communication, and has the advantage of high sensitivity, and can be applied to the sensing fields such as biology, physics, medicine, etc.

The structural main body of the film bulk acoustic resonator is a sandwich structure consisting of electrodes, piezoelectric films and electrodes, namely a layer of piezoelectric film material is sandwiched between two metal electrode layers. By inputting a sinusoidal signal between the two electrodes, the FBAR converts an input electrical signal into mechanical resonance using an inverse piezoelectric effect, and converts the mechanical resonance into an electrical signal output using a piezoelectric effect. The thin film bulk acoustic resonator mainly uses the longitudinal piezoelectric coefficient (d 33) of the piezoelectric thin film to generate the piezoelectric effect, so that the main operation mode thereof is a longitudinal wave mode (Thickness Extensional Mode, abbreviated as TE mode) in the thickness direction.

Fig. 7A is a top view of a bulk acoustic wave resonator according to the prior art, and fig. 7B is a cross-sectional view taken along a folding line A1OA2 in fig. 7A. As shown in fig. 7A-7B, by removing the piezoelectric layer 50 over the fold line B1O' B2, portions of the bottom electrode 40, and the bottom electrode pins 35, and the substrate 10 may be exposed in a top view, each of which is described in detail as follows:

10: the substrate is made of monocrystalline silicon, gallium arsenide, sapphire, quartz, etc.

20: an acoustic mirror, in the example described above an air chamber, may also employ a Bragg reflector or other equivalent acoustically reflective structure.

40 (35)/60 (65): the bottom electrode (pin)/top electrode (pin) can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or composite or alloy thereof.

50: the piezoelectric layer film is made of aluminum nitride, zinc oxide, PZT and other materials and contains rare earth element doped materials with certain atomic ratio.

Fig. 7C shows a schematic diagram of the temperature gradient distribution of the active area AR of the resonator corresponding to fig. 7A (where the dark place indicates a low temperature and the bright place indicates a high temperature), and the temperature highest point is located at Σ in the diagram.

When the resonator is operated, a part of sound vibration energy and electric energy are inevitably converted into heat energy, and as the power of the resonator is increased, the heating problem becomes more remarkable, so that the operating temperature of the resonator is overhigh. The high temperature not only adversely affects the electrical characteristics of the resonator, but also accelerates the aging and damage of the components of the device. The heating problem is particularly pronounced in the central region of the active area of the resonator.

Disclosure of Invention

The invention provides a power enhancement structure arranged at or near the center of a top view of an effective acoustic area of a bulk wave resonator, which can lead the highest temperature point in the resonator and the vibration frequency near the highest temperature point to deviate from a resonance point, thereby achieving the purpose of reducing the temperature of the resonator.

According to an aspect of an embodiment of the present invention, there is provided a bulk acoustic wave resonator including:

a substrate;

an acoustic mirror cavity;

a bottom electrode;

a top electrode;

the piezoelectric layer is formed of a material such as silicon,

wherein:

the overlapped area of the acoustic mirror cavity, the bottom electrode, the piezoelectric layer and the top electrode in the thickness direction of the substrate is an effective area of the resonator; and is also provided with

The utility model discloses an acoustic mirror cavity, including the acoustic mirror cavity, be provided with bearing structure in the acoustic mirror cavity, bearing structure's lower extreme sets up in the bottom of acoustic mirror cavity, bearing structure's upper end be in the high temperature region of active area with the downside of active area is connected or is contacted, the high temperature region is the barycenter of using the active area as the centre of a circle, r is the region of radius, radius r is 50% of the radius of the equivalent circle of active area in the high temperature region, the equivalent circle is: a circle having the center of mass of the effective region as a center and an area of the circle being equal to an area of the effective region.

Optionally, the radius r is 20% of the radius of an equivalent circle of the effective area where the high temperature area is located.

Optionally, the upper end of the support structure is connected to or in contact with the underside of the active area only in the high temperature region of the active area.

Optionally, the supporting structure is a frustum-shaped structure, the cross-sectional area of the upper end of the supporting structure is smaller than the cross-sectional area of the lower end of the supporting structure, and the top of the frustum-shaped structure forms a supporting surface, and the supporting surface is connected with the bottom side of the bottom electrode.

Optionally, the frustum-shaped structure is a quadrangular prism structure or a triangular prism structure or a frustum-shaped structure.

Optionally, the upper end of the supporting structure is provided with a supporting surface, and the supporting surface is connected with the bottom side of the bottom electrode; the lower end of the supporting structure is provided with a fixing surface which is connected with the bottom of the acoustic mirror cavity; the support structure further includes an elastic connection portion connected between the support surface and the fixing surface, the elastic connection portion providing an elastic force such that the support surface faces upward to abut the bottom electrode.

Optionally, the elastic connection portion is a wing portion.

Optionally, a first oblique angle is formed between the wing part and the fixing surface, and the first oblique angle is in the range of 10-80 degrees.

Optionally, the wing is trapezoidal, an upper base of the trapezoid is connected to the supporting surface, and a lower base of the trapezoid is connected to the fixing surface.

Optionally, the wing is serpentine. Further, the end of the serpentine in contact with the support surface is smaller than the end of the serpentine in contact with the stationary surface.

Optionally, the wing comprises a plurality of wings equally angularly spaced in a top view of the resonator, the plurality of wings having the same first oblique angle; and the fixing surface is an annular fixing surface or the fixing surface comprises a plurality of fixing surfaces which are equally angularly spaced in a top view of the resonator, and the plurality of fixing surfaces respectively correspond to the plurality of wings.

Optionally, the support surface has only one support surface, and the plurality of wings are each connected to the one support surface; or the supporting surface is provided with a plurality of supporting surfaces, and the plurality of wing parts are respectively connected with the plurality of supporting surfaces.

Optionally, the wing comprises two wings arranged mirror-symmetrically in a top view of the resonator, the support surface having only one support surface, and both wings being connected to the one support surface.

Optionally, the wing comprises a plurality of wings arranged rotationally symmetrically in a top view of the resonator, the support surface has only one support surface, and the plurality of wings are each connected to the one support surface.

Optionally, the supporting structure is a cylindrical structure with the same cross section, and the top surface of the cylindrical structure forms a supporting surface, and the supporting surface is connected with the bottom side of the bottom electrode.

Optionally, the support structure is a thermally conductive structure adapted to conduct heat from the support structure from a high temperature region of the active area to the substrate.

Optionally, the support structure is connected to the bottom electrode forming surface, and the support structure is connected to the bottom forming surface of the acoustic mirror cavity.

Optionally, the contact area of the support structure with the underside of the active area is no more than 1% of the area of the active area; or the side length of the longest side of the contact surface between the supporting structure and the lower side of the effective area is not more than 1/10 of the longest side length of the effective area; or the longest edge or diameter of the contact surface of the support structure with the underside of the active area is in the range of 0.1-20 μm. Further, the contact area of the support structure and the lower side of the effective area is not more than 0.1% of the area of the effective area; or the side length of the longest side of the contact surface between the supporting structure and the lower side of the effective area is not more than 1/30 of the longest side length of the effective area.

Optionally, the support structure is a first support structure; and the resonator further comprises a plurality of auxiliary supporting structures, the plurality of auxiliary supporting structures are arranged around the first supporting structure, the lower ends of the auxiliary supporting structures are arranged at the bottom of the acoustic mirror cavity, and the upper ends of the auxiliary supporting structures are connected with or contacted with the lower side of the effective area. Further, the plurality of auxiliary support structures are distributed on at least one circumference centered on the centroid of the active area and equally angularly spaced apart on the circumference.

Optionally, the height of the support structure ranges from h±1 μm, where H is the depth of the corresponding acoustic mirror cavity.

According to a further aspect of an embodiment of the present invention, a filter is presented, comprising the resonator described above.

According to a further aspect of embodiments of the present invention, an electronic device is presented, comprising the resonator described above, or the filter described above.

Drawings

These and other features and advantages of the various embodiments of the disclosed invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate like parts throughout the several views, and wherein:

fig. 1A is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

FIG. 1B is a schematic illustration of a support structure disposed in the acoustic mirror cavity of FIG. 1A in accordance with an exemplary embodiment of the present invention;

FIG. 1C is a schematic illustration of the support structure of FIG. 1A according to an exemplary embodiment of the invention;

FIG. 1D is a schematic illustration of the support structure of FIG. 1A according to an exemplary embodiment of the invention;

fig. 2A is a schematic diagram of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

FIG. 2B is a side view of the support structure of FIG. 2A;

fig. 3 is a schematic view of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

fig. 4A is a schematic diagram of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

FIG. 4B is a schematic top view of the support structure of FIG. 4A;

fig. 5A is a schematic diagram of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

FIG. 5B is a schematic top view of the support structure of FIG. 5A;

fig. 6A is a schematic diagram of a first support structure and an auxiliary support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

FIG. 6B is a schematic diagram of the distribution of auxiliary support structures according to an exemplary embodiment of the present invention;

FIG. 6C is a schematic diagram of the distribution of auxiliary support structures according to an exemplary embodiment of the present invention;

FIG. 7A is a top view of a bulk acoustic wave resonator of the prior art;

FIG. 7B is a cross-sectional view taken along the line A1OA2 of FIG. 7A;

fig. 7C is a schematic diagram of a temperature gradient distribution of the effective area AR of the resonator corresponding to fig. 7A, wherein the dark place represents a low temperature, the bright place represents a high temperature, and the highest temperature point is located at Σ in the graph.

Detailed Description

The technical scheme of the invention is further specifically described below through examples and with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of embodiments of the present invention with reference to the accompanying drawings is intended to illustrate the general inventive concept and should not be taken as limiting the invention.

Fig. 1A is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.

Details of each part are described as follows:

20: an acoustic mirror cavity.

30: and a support structure.

As shown in fig. 1A and 1B, a support structure 30 is disposed in the acoustic mirror cavity 20, a lower end of the support structure 30 is disposed at a bottom of the acoustic mirror cavity 20, an upper end of the support structure is connected to a bottom side of the bottom electrode 40 in a high temperature region of the active region, and a height between a lower end and an upper end of the support structure 30 is a depth of the acoustic mirror cavity.

It should be noted that, in the present invention, the "high temperature region" refers to a region having a center of mass of an effective region as a center of a circle, and r as a radius, where r is 50% of a radius of an equivalent circle of the effective region, and further 20%, where the equivalent circle is: a circle having the center of mass of the effective region as a center and an area of the circle being equal to an area of the effective region.

In the present invention, the upper end of the support structure may be located only partially or entirely within the high temperature region, which is within the scope of the present invention.

Since the operation of the resonator is essentially the interaction of the piezoelectric substance with the field, the spatial distribution of the thermal power density of the resonator is directly related to the spatial distribution of the substance in the active area of the resonator, and for a resonator with a convex geometry in the active area, the location of highest thermal power density is located near the center (centroid) of the substance distribution. Although the resonator effective area is composed of different substances such as a metal electrode layer and a piezoelectric layer in the thickness direction, since the thickness of each substance layer is generally uniform (or approximately uniform), the equivalent areal density of the effective area can be considered to be uniform in a plan view. In the above case, the position of the plane centroid of the effective area is the plane geometric center of the area.

Due to the support structure 30, the vibration frequency at or near the highest temperature point of the resonator may be deviated from the resonance point. This helps to reduce the temperature at or near the highest temperature point of the resonator, thereby increasing the power capacity of the entire resonator.

In the case where the support structure 30 itself also has a heat transfer function, it helps to transfer heat from the bottom electrode to the substrate, providing additional heat dissipation channels beyond the edges of the resonator for heat dissipation from the active area of the resonator, and helps to further reduce the temperature of the resonator, thereby increasing the power capacity of the resonator. Based on this, in one embodiment of the invention, the support structure is a thermally conductive structure adapted to conduct heat from the support structure from the high temperature region of the active area to the substrate. Further, the support structure is connected to the bottom electrode forming surface and the support structure is connected to the bottom forming surface of the acoustic mirror cavity.

The support structure 30 is shown in fig. 1A only schematically as being disposed between the bottom electrode and the bottom of the acoustic mirror cavity. The structure of the support structure 30 is specifically described below.

Fig. 1B is a schematic view of a support structure disposed in the acoustic mirror cavity of fig. 1A according to an exemplary embodiment of the present invention, and fig. 1C is a schematic view of the support structure of fig. 1A according to an exemplary embodiment of the present invention. As shown in fig. 1B-1C, the supporting structure is a rectangular pyramid structure with a small top and a large bottom, and the top surface of the rectangular pyramid structure is a supporting surface.

Referring to fig. 1C, the contact surface with the lower electrode at the top of the tapered quadrangular prism is rectangular, and the length a0 of one side of the rectangle ranges from 0.1 to 20 μm, preferably ranges from 0.1 to 10 μm, the length b0 of the other side ranges from 0.1 to 20 μm, preferably ranges from 0.1 to 10 μm, the first included angle α0 of the prism side to the vertical ranges from 10 to 80 degrees, and the second included angle β0 ranges from 10 to 80 degrees; the prism height H01 ranges from H+ -1 μm, where H is the depth of the corresponding resonator acoustic mirror cavity.

The support structure shown in fig. 1B is in the shape of a quadrangular pyramid, but the present invention is not limited thereto. For example, as shown in fig. 1D, the support structure is in the shape of a truncated cone. As shown in FIG. 1D, the top surface and the bottom surface of the conical cylinder are both circular, the circular radius R0 of the top surface ranges from 0.05 to 10 mu m, the preferred range is from 0.05 to 5 mu m, the circular radius R0 of the bottom surface ranges from 1 to 50 mu m, and the height H02 of the conical cylinder ranges from H+/-1 mu m, wherein H is the depth of the acoustic mirror cavity of the corresponding resonator.

Furthermore, although not shown, the support structure may also be in the shape of a triangular pyramid, for example; alternatively, the support structure is a cylindrical structure having the same cross section, such as a cylinder, square cylinder, or the like.

The support structure may be of other forms than the support structure shown in fig. 1A-1D, in particular the support structure has elasticity in the thickness direction of the resonator. In this way, the rigidity of the support structure in the thickness direction of the resonator can be reduced, thereby reducing the impact of the support structure on the resonator and reducing the energy loss.

Fig. 2A is a schematic diagram of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention; fig. 2B is a side view of the support structure of fig. 2A.

Shown in fig. 2A is a support structure 30 having a rectangular base portion with a first side length a3 in the range of 10-50 μm and a second side length b3 in the range of 10-50 μm; the top contact part is rectangular, the first side length a1 of the contact part ranges from 0.1 to 20 mu m, preferably ranges from 0.1 to 10 mu m, and the second side length b1 ranges from 0.1 to 20 mu m, preferably ranges from 0.1 to 10 mu m; furthermore, between the base part and the contact part, an inclined connecting part is formed, the connecting part is trapezoid, the length b2 of the bottom of the trapezoid ranges from 2 mu m to 40 mu m, and the upper bottom of the trapezoid is overlapped with the second side of the contact part.

FIG. 2B is a side view of the structure of FIG. 4A, wherein the connection portion of the structure is at an angle alpha 1 of 10-80 degrees to the horizontal; the overall height H03 ranges from H+ -1 μm, where H is the depth of the cavity of the corresponding resonator acoustic mirror. The thickness T1 of the support structure ranges from 0.01 to 0.5 μm.

It should be noted that the range h±1 μm of the height H03 of the support structure is applicable not only to the present embodiment but also to other embodiments of the present invention.

Based on the above, in the present invention, the upper end of the support structure has a support surface connected to the bottom side of the bottom electrode; the lower end of the supporting structure is provided with a fixing surface which is connected with the bottom of the acoustic mirror cavity; the support structure further includes an elastic connection portion connected between the support surface and the fixing surface, the elastic connection portion providing an elastic force such that the support surface faces upward to abut the bottom electrode. As shown in fig. 2A, the elastic connection portion may be a wing portion. As shown in fig. 2B, a first oblique angle α1 is formed between the wing portion and the fixing surface, and the first oblique angle is in the range of 10-80 degrees.

As shown in fig. 2A, the wing is trapezoidal, with the upper base of the trapezoid being connected to the support surface and the lower base of the trapezoid being connected to the fixing surface.

Fig. 3 is a schematic view of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. As shown in fig. 3, the elastic connection or wing is serpentine to further reduce its stiffness and increase its freedom. As shown in fig. 3, the end of the serpentine in contact with the support surface is smaller than the end of the serpentine in contact with the fixing surface, in other words, in fig. 3, the lower end of the serpentine in the wing is larger and the upper end is smaller, which facilitates the deformation of the wing.

Fig. 2A and 3 only show a support structure having a single wing, but the present invention is not limited thereto.

Fig. 4A is a schematic diagram of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention; fig. 4B is a schematic top view of the support structure of fig. 4A. Fig. 4A and 4B show mirror symmetrical support structures. To enhance the stability of the support structure, the structure of fig. 2A may be mirror extended to form the symmetrical power enhancement structure of fig. 4A. As can be seen from the top view of the structure in fig. 4B, the support structure is symmetrical about straight lines L1L2 and L3L 4. In other words, in the embodiment of fig. 4A and 4B, the wing comprises two wings arranged mirror-symmetrically in a top view of the resonator, the support surface having only one support surface, and both wings being connected to the one support surface.

Fig. 5A is a schematic diagram of a support structure of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention; fig. 5B is a schematic top view of the support structure of fig. 5A. Fig. 5A and 5B show that the support structure is in the form of a rotationally symmetrical structure. Specifically, the support structure was made as shown in fig. 5A, which has an annular base portion, a circular contact portion, and 3 fan-shaped connection portions. The total thickness of the supporting structure is T2, the range of T2 is 0.01-0.5 mu m, and the total height H04 is H+/-1 mu m, wherein H is the depth of the cavity of the acoustic mirror of the corresponding resonator. FIG. 5B is a top view of the structure of FIG. 5A, showing the critical dimensions of the support structure, with a base portion ring inner diameter R1 ranging from 1 to 50 μm and an outer radius R2 ranging from 5 to 100 μm; the contact portion circular radius r1 ranges from 0.05 to 10 μm, preferably ranges from 0.05 to 5 μm; the included angle alpha 2 of the plane projection of the fan-shaped connecting part ranges from 10 degrees to 40 degrees. This structure reduces structural rigidity and has higher stability. In other words, in the embodiment of fig. 5A and 5B, the wing comprises a plurality of wings arranged rotationally symmetrically in a top view of the resonator, the support surface having only one support surface, and the plurality of wings each being connected to the one support surface.

Although only one support surface is shown in the embodiments shown in the above drawings, the present invention is not limited thereto, and a plurality of support surfaces may be provided, but these support surfaces are all connected to a high temperature region of the effective region.

In addition, the present invention may also be provided with additional auxiliary support structures in addition to the support structures described above, as shown in fig. 6A-6C.

Referring to fig. 6A, in addition to the support structure 30 employed in the heat generating center region, a number of auxiliary support structures 31 are added around it. The advantage of many bearing structure is: the heat conduction capability can be further enhanced by increasing the number of contact surfaces; the structural stability is improved; the multiple support structures can also play a role in inhibiting parasitic mode vibration in the resonator by adopting a certain distribution mode.

As shown in fig. 6B, the contact surfaces (hatched circular areas in the figure, rectangular areas may also be used) between the support structure and the effective acoustic area of the resonator are distributed on several concentric circles centered on the geometric center of the central contact surface, and the concentric circles have radii Rm1, rm2, rm3, etc. from inside to outside. Wherein the radius of the innermost circle ranges from 1 to 50 mu m, and the radius of each circle from inside to outside is different from the radius of the adjacent inner circle by 1 to 50 mu m. In addition, the contact surfaces are also distributed along multiple radial directions, and the radial directions equally divide the circumference, for example, the circumference 4 is equally divided in the radial direction in fig. 6B, and the circumference is equally divided in the radial direction in fig. 6C, but the equally divided number can be other integers, such as 3,6,8,9 …, etc.

The contact area between the supporting structure and the effective area is too small, so that the heat dissipation effect is not obvious, but too large area can reduce the Q value of the resonator and can also cause negative effects such as parasitic mode enhancement. Therefore, it is also noted that in the present invention, the contact area of the support structure with the underside of the active area or with the bottom electrode in the active area may be limited. Specifically, the contact area between the support structure and the lower side of the effective area is not more than 1% of the area of the effective area, and further, not more than 0.1%; or the side length of the longest side of the contact surface between the supporting structure and the lower side of the effective area is not more than 1/10 of the longest side length of the effective area, and further, not more than 1/30; or the longest edge or diameter of the contact surface of the support structure with the underside of the active area is in the range of 0.1-20 μm.

In the present invention, the numerical range may be, for example, a median value of the range, in addition to the end point value (inclusive) or the adjacent end point value (exclusive) within the range.

Based on the above, the invention provides the following technical scheme:

1. a bulk acoustic wave resonator comprising:

a substrate;

an acoustic mirror;

a bottom electrode;

a top electrode;

the piezoelectric layer is formed of a material such as silicon,

wherein:

the area where the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode overlap in the thickness direction of the substrate is an effective area of the resonator; and is also provided with

2. A filter comprises the resonator.

3. An electronic device comprising a resonator as described above, or a filter as described above. It should be noted that, the electronic devices herein include, but are not limited to, intermediate products such as a radio frequency front end, a filtering and amplifying module, and end products such as a mobile phone, a WIFI, and an unmanned aerial vehicle.

Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Claims

1. A bulk acoustic wave resonator comprising:

a substrate;

an acoustic mirror cavity;

a bottom electrode;

a top electrode;

the piezoelectric layer is formed of a material such as silicon,

wherein:

The acoustic mirror comprises an acoustic mirror cavity, wherein a supporting structure is arranged in the acoustic mirror cavity, the lower end of the supporting structure is arranged at the bottom of the acoustic mirror cavity, the upper end of the supporting structure is connected with or contacted with the lower side of an effective area at least in part of the high-temperature area of the effective area, the high-temperature area is an area taking the mass center of the effective area as the center of a circle and r as the radius, the radius r is 50% of the radius of an equivalent circle of the effective area where the high-temperature area is located, and the equivalent circle is: a circle having the center of mass of the effective region as a center and an area of the circle being equal to an area of the effective region.

2. The resonator of claim 1, wherein:

the radius r is 20% of the radius of an equivalent circle of the effective area where the high temperature area is located.

3. The resonator of claim 1, wherein:

the upper end of the support structure is connected or contacted with the lower side of the effective area only in the high temperature area of the effective area.

4. A resonator according to any of claims 1-3, wherein:

the supporting structure is a frustum-shaped structure, the cross-sectional area of the upper end of the supporting structure is smaller than that of the lower end of the supporting structure, and the top of the frustum-shaped structure forms a supporting surface which is connected with the bottom side of the bottom electrode.

5. The resonator of claim 4, wherein:

the frustum-shaped structure is a quadrangular prism structure or a triangular prism structure or a frustum-shaped structure.

6. A resonator according to any of claims 1-3, wherein:

the upper end of the supporting structure is provided with a supporting surface which is connected with the bottom side of the bottom electrode; the lower end of the supporting structure is provided with a fixing surface which is connected with the bottom of the acoustic mirror cavity; the support structure further includes an elastic connection portion connected between the support surface and the fixing surface, the elastic connection portion providing an elastic force such that the support surface faces upward to abut the bottom electrode.

7. The resonator of claim 6, wherein:

the elastic connection part is a wing-shaped part.

8. The resonator of claim 7, wherein:

a first oblique angle is formed between the wing-shaped part and the fixing surface, and the first oblique angle is in the range of 10-80 degrees.

9. The resonator according to claim 7 or 8, wherein:

the wing is trapezoidal, the upper bottom of which is connected to the supporting surface, and the lower bottom of which is connected to the fixing surface.

10. The resonator according to claim 7 or 8, wherein:

the wing is serpentine.

11. The resonator of claim 10, wherein:

the side length of one end of the snake shape contacting with the supporting surface is smaller than that of one end of the snake shape contacting with the fixing surface.

12. The resonator according to claim 7 or 8, wherein:

the wing comprises a plurality of wings equally angularly spaced in a top view of the resonator, the plurality of wings having the same first oblique angle; and is also provided with

The fixing surface is an annular fixing surface or comprises a plurality of fixing surfaces which are equally angularly spaced in a top view of the resonator, and the plurality of fixing surfaces respectively correspond to the plurality of wings.

13. The resonator of claim 12, wherein:

the support surface has only one support surface, and the plurality of wings are each connected to the one support surface; or alternatively

The support surface is provided with a plurality of support surfaces, and the plurality of wing-shaped parts are respectively connected with the plurality of support surfaces in a one-to-one mode.

14. The resonator of claim 13, wherein:

the wing comprises two wings arranged mirror-symmetrically in a top view of the resonator, the support surface having only one support surface, and both wings being connected to the one support surface.

15. The resonator of claim 13, wherein:

the wing comprises a plurality of wings arranged rotationally symmetrically in a top view of the resonator, the support surface having only one support surface, and the plurality of wings each being connected to the one support surface.

16. A resonator according to any of claims 1-3, wherein:

the supporting structure is a cylindrical structure with the same section, and the top surface of the cylindrical structure forms a supporting surface which is connected with the bottom side of the bottom electrode.

17. The resonator of claim 1, wherein:

the support structure is a thermally conductive structure adapted to conduct heat from the support structure from a high temperature region of the active area to the substrate.

18. The resonator of claim 17, wherein:

the support structure is connected with the bottom electrode forming surface, and the support structure is connected with the bottom forming surface of the acoustic mirror cavity.

19. A resonator according to any of claims 1-3, wherein:

the contact area of the supporting structure and the lower side of the effective area is not more than 1% of the area of the effective area; or alternatively

The side length of the longest side of the contact surface between the supporting structure and the lower side of the effective area is not more than 1/10 of the longest side length of the effective area; or alternatively

The length of the longest edge or diameter of the contact surface of the support structure with the underside of the active area is in the range of 0.1-20 μm.

20. The resonator of claim 19, wherein:

the contact area of the supporting structure and the lower side of the effective area is not more than 0.1% of the area of the effective area; or alternatively

The side length of the longest side of the contact surface between the supporting structure and the lower side of the effective area is not more than 1/30 of the longest side length of the effective area.

21. A resonator according to any of claims 1-3, wherein:

the support structure is a first support structure; and is also provided with

The resonator further comprises a plurality of auxiliary support structures, the plurality of auxiliary support structures are arranged around the first support structure, the lower ends of the auxiliary support structures are arranged at the bottom of the acoustic mirror cavity, and the upper ends of the auxiliary support structures are connected with or contacted with the lower side of the effective area.

22. The resonator of claim 21, wherein:

the plurality of auxiliary support structures are distributed on at least one circumference centered on the centroid of the active area and equiangularly spaced apart on the circumference.

23. The resonator of claim 1, wherein:

the height of the support structure ranges from H+/-1 mu m, wherein H is the depth of the corresponding acoustic mirror cavity.

24. A filter, comprising:

the bulk acoustic wave resonator according to any of claims 1-23.

25. An electronic device comprising a bulk acoustic wave resonator according to any of claims 1-23 or comprising a filter according to claim 24.