CN219304811U - Resonator with a plurality of resonators - Google Patents

Abstract

The utility model provides a resonator structure, which comprises a substrate, a bottom electrode formed on the substrate, a piezoelectric layer formed on the bottom electrode, and a top electrode formed on the piezoelectric layer, the top electrode 1. The overlapping area of the piezoelectric layer and the bottom electrode is the resonant area, and the resonator also includes a space formed in the resonant area, the surface of the bottom electrode away from the substrate is the first surface, and the surface of the top electrode facing the piezoelectric layer is the second surface , the space extends from the first surface to the direction away from the piezoelectric layer and/or extends from the second surface to the direction away from the piezoelectric layer; or, the piezoelectric layer includes a bottom surface facing the bottom electrode and a bottom surface opposite to the bottom surface and facing the top On the top surface of the electrode, the space extends from the bottom surface toward the top surface or extends from the top surface toward the bottom surface. Compared with the related art, the resonator structure of the utility model can reduce the energy loss of the device, improve the Q value and reduce the insertion loss.

Description

resonator

【Technical field】

The utility model relates to the technical field of resonators, in particular to a resonator structure.

【Background technique】

With the increasing number of smart devices and the continuous popularization of Internet of Things and 5G technologies, the demand for high-performance filters and multiplexers is increasing. As an important part of filters and multiplexers, acoustic resonators have been the focus of research in recent years. The current mainstream acoustic resonance technologies include surface acoustic wave technology SAW (Surface Acoustic Wave) and bulk acoustic wave technology BAW (Bulk Acoustic Wave). Due to the simple manufacturing process and low cost, the resonator using SAW technology occupies the mainstream market of medium and low frequency (below 2GHz). The disadvantages of SAW resonators are low quality factor value, poor temperature drift of materials and poor compatibility with semiconductor process. The filter formed by this resonator has poor square coefficient, high insertion loss, and large center frequency drift with temperature. What is more fatal is that as the frequency increases, the spacing between the interfinger electrodes of the SAW resonator decreases, which puts higher requirements on the process and the reliability of the device deteriorates. These shortcomings are hindering the application of SAW resonators to higher frequency band. The emergence of BAW resonators has improved the shortcomings of many SAW resonators, and the mature semiconductor process has good compatibility with its manufacture. However, due to the complex process and high manufacturing difficulty of BAW resonators, the cost remains high, making them in the It is difficult to completely replace the SAW resonator in the medium and high frequency bands, and it is even uncompetitive at low frequencies. In addition to the development in the field of communication, due to its excellent performance, BAW resonators are also widely used in piezoelectric microphones, pressure sensors or other sensor fields.

Different from SAW resonators, BAW resonators use longitudinal waves to generate resonance in piezoelectric films, and the propagation direction of longitudinal waves is the thickness direction of piezoelectric materials. By adjusting the thickness of the piezoelectric material and the electrode material, the resonant frequency of the resonator can be adjusted conveniently. In order to generate the resonance, in addition to the piezoelectric material and the oppositely arranged electrode layers above and below it for generating the electrical excitation, there are usually also acoustic mirrors which reflect the wave energy at the interface. Air or Bragg mirrors are the most commonly used mirror structures. The Bragg reflector adopts a laminated structure of multiple groups of low acoustic impedance materials and high acoustic impedance materials alternately to reflect waves. Although this kind of mirror has high reflectivity, it still cannot avoid energy leakage along the mirror. Compared with Bragg reflectors, air reflects waves better and blocks the path of energy leakage, so resonators with higher quality factors can often be manufactured. In order to introduce air into the resonant structure as a mirror, the related technology is to make a cavity structure in or on the substrate before depositing the electrode layer and the piezoelectric layer. Taking the formation of a cavity in the substrate as an example, Fill the cavity with a sacrificial material to make the surface flat, then deposit an electrode layer and a piezoelectric layer over the cavity and the substrate, and finally contact the sacrificial material with a corrosive liquid or atmosphere that can corrode the sacrificial material through a pre-set release channel, The cavity is freed to form an air mirror structure.

When the BAW resonator is working, a high-frequency voltage is applied to the top electrode and the bottom electrode respectively. Under the action of the alternating electric field, the piezoelectric material deforms, and the cavity or the suspended film above the acoustic mirror oscillates, resulting in a The longitudinal waves in the direction and the clutter propagating in the direction perpendicular to the thickness (transverse direction). Under a specific frequency alternating voltage, the suspended film will resonate to achieve special electrical characteristics. In the prior art, although the main mode at resonance is the longitudinal wave mode, there are still some spurious modes formed along with the excitation of the longitudinal wave. These parasitic modes can be standing waves, which form spurious peaks on the electrical characteristic curve of the device, increasing the in-band ripple and insertion loss of the filter; they can also be laterally propagating clutter, causing energy leakage and increasing the insertion loss of the filter , reduce the quality factor (Q value) of the device.

Therefore, it is necessary to provide a new resonator to solve the above technical problems.

【Content of utility model】

The purpose of the utility model is to provide a resonator structure which reduces energy loss, improves device Q value, and reduces insertion loss.

In order to achieve the above purpose, the utility model provides a resonator,

include:

Substrate;

a bottom electrode formed on the substrate, the surface of the bottom electrode away from the substrate being the first surface;

a piezoelectric layer formed over the bottom electrode;

The top electrode is formed on the piezoelectric layer, and the surface of the top electrode facing the piezoelectric layer is the second surface; the overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is resonant district;

a space formed in the resonance region;

The space extends from the first surface in a direction away from the piezoelectric layer and/or extends from the second surface in a direction away from the piezoelectric layer.

Preferably, a cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or is provided in the substrate.

Preferably, an acoustic mirror is provided between the substrate and the bottom electrode, and the acoustic mirror includes at least one layer of a first acoustic impedance material layer and at least one layer of a second acoustic impedance material layer, and at least one layer of the The first acoustic impedance material layer and at least one layer of the second acoustic impedance material layer are sequentially overlapped and disposed on the substrate, the first acoustic impedance material layer and the second acoustic impedance material layer The number of layers is equal.

Preferably, the acoustic impedance value of the first acoustic impedance material layer is greater than the acoustic impedance value of the second acoustic impedance material layer.

Preferably, the bottom electrode includes a third surface opposite to the first surface, and the space is spaced apart from the third surface.

Preferably, the top electrode includes a fourth surface opposite to the second surface, and the space is spaced apart from the fourth surface.

Preferably, the top electrode includes a side surface connecting the second surface and the fourth surface, and the space extends to the side surface.

Preferably, the space is filled with one or more materials such as air, silicon dioxide, silicon, silicon nitride and the like.

Preferably, the bottom electrode and the top electrode can be made of one or more materials such as molybdenum, tungsten, platinum, aluminum, etc., and the piezoelectric layer can be made of aluminum nitride, scandium-doped aluminum nitride, zinc oxide , PZT and other one or more piezoelectric materials.

The utility model also provides a resonator, comprising:

Substrate;

a bottom electrode formed on the substrate; a piezoelectric layer formed on the bottom electrode;

a top electrode, formed on the piezoelectric layer; the overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is a resonant region;

a space formed in the resonance region;

The piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface opposite to the bottom surface and facing the top electrode, and the space extends from the bottom surface toward the top surface or extends from the bottom surface. The top surface extends toward the bottom surface.

Preferably, a cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or within the substrate.

Preferably, an acoustic mirror is provided between the substrate and the bottom electrode, and the acoustic mirror includes at least one layer of a first acoustic impedance material layer and at least one layer of a second acoustic impedance material layer, and at least one layer of the The first acoustic impedance material layer and at least one layer of the second acoustic impedance material layer are sequentially overlapped and disposed on the substrate, the first acoustic impedance material layer and the second acoustic impedance material layer The number of layers is equal.

Preferably, the acoustic impedance value of the first acoustic impedance material is greater than the acoustic impedance value of the second acoustic impedance material.

Preferably, the space extends from the bottom surface of the piezoelectric layer to the top surface.

Preferably, the space is filled with one or more materials such as air, silicon dioxide, silicon, silicon nitride and the like.

Preferably, the bottom electrode and the top electrode can be made of one or more materials such as molybdenum, tungsten, platinum, aluminum, etc., and the piezoelectric layer can be made of aluminum nitride, scandium-doped aluminum nitride, zinc oxide , PZT and other one or more piezoelectric materials.

Compared with the related art, in the resonator of the present utility model, the overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is a resonant region, and the resonator also includes a resonator formed in the resonant region space, the bottom electrode includes a first surface close to the piezoelectric layer, the top electrode includes a second surface facing the piezoelectric layer, and the space is away from the piezoelectric layer from the first surface Extending in a layer direction and/or extending away from the piezoelectric layer from the second surface; or the piezoelectric layer includes a bottom surface facing the bottom electrode and a bottom surface opposite to the bottom surface and facing the piezoelectric layer. On the top surface of the top electrode, the space extends from the bottom surface toward the top surface or extends from the top surface toward the bottom surface; that is, through the above-mentioned structural arrangement, a space is introduced in the resonance region, and the lateral Most of the propagating clutter will be reflected back to the resonance area, reducing the clutter that propagates outside the resonance area, so that most of the energy is confined in the resonance area, reducing energy loss, increasing the Q value of the resonator, and reducing insertion loss. At the same time, after applying a high-frequency voltage, the main mode and the parasitic mode will be formed in the two resonance regions separated by space, and in the space region, the piezoelectric layer and the top electrode are separated by an air gap, so in this region No wave excitation will be generated; therefore, the counterpropagating spurious modes in the two space-separated resonance regions cancel each other out, reducing the propagation of lateral clutter and the formation of lateral standing waves in the entire resonance region; by adjusting the two resonance regions And the size of the space area, can selectively eliminate or reduce the spurious peak of a specific frequency, so as to reduce the ripple in the passband, reduce the insertion loss, and improve the performance of the device.

【Description of drawings】

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some implementations of the present invention. For example, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work, wherein:

Fig. 1 is the structural schematic diagram of a resonator of the utility model embodiment;

Fig. 2 is a sectional view along A-A of Fig. 1;

Fig. 3 is a cross-sectional view of a first embodiment of the utility model provided with an acoustic mirror;

Fig. 4 is an exploded schematic diagram of a resonator according to Embodiment 1 of the present invention;

Fig. 5 is another exploded schematic diagram of a resonator according to the embodiment of the present invention;

Fig. 6 is a cross-sectional view of the second resonator of the utility model embodiment;

Fig. 7 is a cross-sectional view of a three-resonator embodiment of the present invention;

Fig. 8 is a cross-sectional view of a four-resonator embodiment of the utility model;

Fig. 9 is a cross-sectional view of a fifth resonator according to the embodiment of the present invention.

【Detailed ways】

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Embodiment one

Please refer to FIGS. 1-5 at the same time. The present invention provides a resonator 100 , which includes a substrate 1 , a bottom electrode 2 , a piezoelectric layer 3 and a top electrode 4 stacked in sequence from bottom to top.

Specifically, the bottom electrode 2 is formed on the substrate 1; the piezoelectric layer 3 is formed on the bottom electrode 2; the top electrode 4 is formed on the piezoelectric layer 3; the top electrode 4, The overlapping area of the piezoelectric layer 3 and the bottom electrode 2 is a resonance area 5; the resonator 100 also includes a space 10 formed in the resonance area 5;

The top electrode 4 includes a second surface 4a and a fourth surface 4b opposite to the second surface 4a, the second surface 4a is the surface of the top electrode 4 facing the piezoelectric layer 3; the space 10 extends from the The second surface 4a extends away from the piezoelectric layer 3, and the space 10 is spaced apart from the fourth surface 4b, that is, in this embodiment, the space 10 does not penetrate the top electrode 4; as shown in FIG. 2 As shown, the substrate 1 is provided with a cavity 110, and the cavity 110 is located between the substrate 1 and the bottom electrode 2 or is provided in the substrate 1, of course, in other embodiments The cavity 110 may not be provided, and it is specifically designed according to actual needs.

As shown in FIG. 3, an acoustic mirror 12 is provided between the substrate 1' and the bottom electrode 2', and the acoustic mirror 12 includes at least one layer of a first acoustic impedance material layer 12a and at least one layer of The second acoustic impedance material layer 12b, at least one layer of the first acoustic impedance material layer a and at least one layer of the second acoustic impedance material layer 12b are successively overlapped and arranged on the substrate 1', the first acoustic impedance material layer a The number of layers of an acoustic impedance material layer 12a is equal to that of the second acoustic impedance material layer 12b; preferably, the acoustic impedance value of the first acoustic impedance material layer 12a is greater than that of the second acoustic impedance material layer 12b Acoustic impedance value. The first acoustic impedance material layer 12a can be high acoustic impedance material such as tungsten, molybdenum, and the second acoustic impedance material layer 12b can be silicon dioxide, silicon nitride, aluminum nitride and other low acoustic impedance material . The top electrode 4' includes a side surface 4c' connecting the second surface 4a' and the fourth surface 4b', and the space 10' may extend to the side surface 4c'. It should be noted that the substrate 1 of the present invention may or may not be provided with a cavity 110 or an acoustic mirror 12 may be provided between the substrate 1' and the bottom electrode 2', and the space 10 or 10' may be Extending to or not extending to the side surface of the top electrode 4 can be selected according to the actual product design, and will not be described in detail below.

The orthographic projection of the top electrode 4 onto the substrate 1 after removing the part connected to the external circuit is an apodized hexagon, and of course it can also be in other shapes, such as an apodized pentagon or an ellipse. The polygon is a non-regular hexagon, and similarly the apodized pentagon is a non-regular pentagon.

Referring to FIG. 2 , the resonant area 5 includes a first resonant area 51 surrounded by the space 10 , a second resonant area 52 corresponding to the space 10 , and a third resonant area 53 outside the space 10 .

After the high-frequency voltage is applied, both the main mode and the parasitic mode will be formed in the first resonant region 51 and the third resonant region 53, and in the second resonant region 52, the sealed space 10 isolates the piezoelectric layer 3 and the top Electrode 4, so the excitation of wave can not be produced in the second resonant region 52; As shown by the arrow on the top of Fig. 2, the spurious modes propagating in the first resonant region 51 and the third resonant region 53 cancel each other out, reduce the whole resonant region 5. The propagation of transverse clutter and the formation of transverse standing waves; by adjusting the size of the first resonant region 51, the second resonant region 52 and the third resonant region 53, the clutter peaks of specific frequencies can be selectively eliminated or reduced, The purpose of reducing the ripple in the passband, reducing the insertion loss and improving the performance of the device is achieved.

In this embodiment, the space is filled with one or more materials such as air, silicon dioxide, silicon, and silicon nitride. Both the bottom electrode 2 and the top electrode 4 are made of one or more materials such as molybdenum, tungsten, platinum, aluminum, etc., and the piezoelectric layer 3 is made of aluminum nitride, scandium-doped aluminum nitride, zinc oxide, It is made of one or more piezoelectric materials such as PZT, and of course it can also be made of other materials.

Embodiment two

Please refer to FIG. 6 , this embodiment provides a resonator 200 whose structure is substantially the same as that of the resonator 100 in Embodiment 1, the difference is that the bottom electrode 22 includes a first surface 22 a and is connected to the first surface 22 a. The third surface 22b opposite to the surface 22a, the first surface 22a is the surface of the bottom electrode 22 away from the substrate 12; the space 102 extends from the first surface 22a to the direction away from the piezoelectric layer 32 and thus The space 102 is spaced apart from the third surface 22b.

Of course, Embodiment 1 and Embodiment 2 can also be combined, that is, the space 102 includes two, one of the spaces 102 extends away from the first surface 22a to the direction away from the piezoelectric layer 32, and the other space 102 extends from the first surface 22a The second surface 42a extends away from the piezoelectric layer 32, which can be adjusted according to actual needs.

Embodiment three

Referring to FIG. 7 , this embodiment provides a resonator 300 whose structure is substantially the same as that of the resonator 100 in Embodiment 1, except that the piezoelectric layer 33 includes a bottom surface facing the bottom electrode 23 332 and the top surface 331 opposite to the bottom surface 332 and facing the top electrode 43, the space 103 extends from the top surface 331 toward the bottom surface 332, and the space 103 does not penetrate through the piezoelectric Layer 33.

Embodiment four

Referring to FIG. 8 , this embodiment provides a resonator 400 whose structure is substantially the same as that of the resonator 100 in Embodiment 1, except that the piezoelectric layer 34 includes a bottom surface facing the bottom electrode 24 342 and a top surface 341 opposite to the bottom surface 342 and facing the top electrode 44, the space 104 extends from the bottom surface 342 toward the top surface 341, and the space 104 does not pass through the piezoelectric layer 34 .

Embodiment five

Referring to FIG. 9 , this embodiment provides a resonator 500 whose structure is substantially the same as that of the resonator 300 in Embodiment 3, except that the space 105 extends from the top surface 351 of the piezoelectric layer 35 To the bottom surface 352 , that is, the space 105 reaches the maximum, the energy loss is less, the Q value of the resonator is improved, and the insertion loss is reduced.

Compared with the related art, in the resonator of the present utility model, the overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is a resonant region, and the resonator also includes a resonator formed in the resonant region space, the bottom electrode includes a first surface close to the piezoelectric layer, the top electrode includes a second surface facing the piezoelectric layer, and the space is away from the piezoelectric layer from the first surface Extending in a layer direction and/or extending away from the piezoelectric layer from the second surface; or the piezoelectric layer includes a bottom surface facing the bottom electrode and a bottom surface opposite to the bottom surface and facing the piezoelectric layer. On the top surface of the top electrode, the space extends from the bottom surface toward the top surface or extends from the top surface toward the bottom surface; that is, through the above-mentioned structural arrangement, a space is introduced in the resonance region, and the lateral Most of the propagating clutter will be reflected back to the resonance area, reducing the clutter that propagates outside the resonance area, so that most of the energy is confined in the resonance area, reducing energy loss, increasing the Q value of the resonator, and reducing insertion loss. At the same time, after applying a high-frequency voltage, the main mode and the parasitic mode will be formed in the two resonance regions separated by space, and in the space region, the piezoelectric layer and the top electrode are separated by an air gap, so in this region No wave excitation will be generated; therefore, the counterpropagating spurious modes in the two space-separated resonance regions cancel each other out, reducing the propagation of lateral clutter and the formation of lateral standing waves in the entire resonance region; by adjusting the two resonance regions And the size of the space area, can selectively eliminate or reduce the spurious peak of a specific frequency, so as to reduce the ripple in the passband, reduce the insertion loss, and improve the performance of the device.

What has been described above is only the embodiment of the utility model, and it should be pointed out that for those of ordinary skill in the art, improvements can also be made without departing from the inventive concept of the utility model, but these all belong to Protection scope of the present utility model.

Claims (12)

1. A resonator, characterized in that, comprising: Substrate; a bottom electrode formed on the substrate, the surface of the bottom electrode away from the substrate being the first surface; a piezoelectric layer formed over the bottom electrode; The top electrode is formed on the piezoelectric layer, and the surface of the top electrode facing the piezoelectric layer is the second surface; the overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is resonant district; a space formed in the resonance region; The space extends from the first surface in a direction away from the piezoelectric layer and/or extends from the second surface in a direction away from the piezoelectric layer. 2. The resonator according to claim 1, wherein a cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or is provided in the substrate. 3. The resonator according to claim 1, wherein an acoustic mirror is provided between the substrate and the bottom electrode, and the acoustic mirror includes at least one layer of a first acoustic impedance material layer and at least A layer of second acoustic impedance material, at least one layer of the first acoustic impedance material and at least one layer of the second acoustic impedance material are successively overlapped and disposed on the substrate, the first acoustic impedance The number of impedance material layers is equal to that of the second acoustic impedance material layer. 4. The resonator according to claim 3, wherein the acoustic impedance value of the first acoustic impedance material layer is greater than the acoustic impedance value of the second acoustic impedance material layer. 5. The resonator according to claim 1, wherein the bottom electrode comprises a third surface opposite to the first surface, and the space is spaced apart from the third surface. 6. The resonator according to claim 1, wherein the top electrode comprises a fourth surface opposite to the second surface, and the space is spaced apart from the fourth surface. 7. The resonator according to claim 6, wherein the top electrode includes a side surface connecting the second surface and the fourth surface, and the space extends to the side surface. 8. A resonator, characterized in that, comprising: Substrate; a bottom electrode formed on the substrate; a piezoelectric layer formed on the bottom electrode; a top electrode, formed on the piezoelectric layer; the overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is a resonant region; a space formed in the resonance region; The piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface opposite to the bottom surface and facing the top electrode, and the space extends from the bottom surface toward the top surface or extends from the bottom surface. The top surface extends toward the bottom surface. 9. The resonator according to claim 8, wherein a cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or within the substrate. 10. The resonator according to claim 8, characterized in that an acoustic mirror is provided between the substrate and the bottom electrode, and the acoustic mirror includes at least one layer of a first acoustic impedance material layer and at least A layer of second acoustic impedance material, at least one layer of the first acoustic impedance material and at least one layer of the second acoustic impedance material are successively overlapped and disposed on the substrate, the first acoustic impedance The number of impedance material layers is equal to that of the second acoustic impedance material layer. 11. The resonator according to claim 10, wherein the acoustic impedance value of the first acoustic impedance material is greater than the acoustic impedance value of the second acoustic impedance material. 12. The resonator of claim 8, wherein the space extends from the bottom surface of the piezoelectric layer to the top surface.

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