WO2022000809A1 - Resonator and method for making same - Google Patents

Abstract

Provided in the present disclosure is a resonator structure, comprising 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 overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is a resonating area. The resonator also comprises space formed in the resonating area. The surface of the bottom electrode away from the substrate is a first surface, and the surface of the top electrode facing the piezoelectric layer is a second surface. The space extends from the first surface towards a direction away from the piezoelectric layer and/or extends from the second surface towards a direction away from the piezoelectric layer. Alternatively, the piezoelectric layer comprises a bottom surface facing the bottom electrode and a top surface arranged opposite to the bottom surface and facing the top surface of the top electrode, and the space extends from the bottom surface towards the top surface or extends from the top surface towards the bottom surface. Also provided in the present disclosure is a method for making the resonator. Compared to the related art, the resonator structure in the present disclosure can reduce the energy loss of a device, increase the Q value, and reduce insertion loss.

Description

Resonator and method of making the same technical field

The invention relates to the technical field of resonators, in particular to a resonator structure and a preparation method thereof.

Background technique

With the increasing number of smart devices and the growing popularity of IoT and 5G technologies, there is an increasing demand for high-performance filters and multiplexers. 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). Resonators using SAW technology occupy the mainstream market of mid-low frequency (below 2GHz) due to their simple manufacturing process and low cost. Disadvantages of SAW resonators are low quality factor values, poor temperature drift of materials and poor compatibility with semiconductor processes. The filter formed by this resonator has poor square coefficient, high insertion loss, and large center frequency drift with temperature. What's more fatal is that as the frequency increases, the spacing between the electrodes of the SAW resonator decreases, which puts forward 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 resonator 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 resonator itself, the cost remains high, making it in It is difficult to completely replace SAW resonators in the mid and high frequency bands, and it is not even competitive at low frequencies. In addition to its development in the field of communications, BAW resonators are also widely used in piezoelectric microphones, pressure sensors or other sensor fields due to their excellent performance.

Different from the SAW resonator, the BAW resonator uses longitudinal waves to generate resonance in the piezoelectric film, and the propagation direction of the longitudinal waves is the thickness direction of the piezoelectric material. By adjusting the thickness of the piezoelectric material and the electrode material, the resonant frequency of the resonator can be easily adjusted. In order to generate resonance, in addition to piezoelectric material and electrode layers arranged oppositely above and below it to generate electrical excitation, there are usually acoustic mirrors that reflect the wave energy at the interface. Air or Bragg mirrors are the most commonly used mirror structures. The Bragg reflector adopts a stacked structure of alternating layers of low-acoustic impedance materials and high-acoustic impedance materials to reflect waves. Although this kind of mirror has high reflectivity, it still cannot avoid the leakage of energy along the mirror. Compared with Bragg mirrors, air reflects waves better and blocks the way of energy leakage, so resonators with higher quality factors can often be fabricated. In order to introduce air as a mirror in the resonant structure, the related technology is to make a cavity structure in or on the substrate before depositing the electrode layer and the piezoelectric layer. Taking forming a cavity in the substrate as an example, Filling the sacrificial material in the cavity to make the surface flat, then depositing an electrode layer and a piezoelectric layer over the cavity and the substrate, and finally contacting the sacrificial material with an etchant or atmosphere that can corrode the sacrificial material through a pre-reserved release channel, The cavity is released 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 is deformed, and the suspended film layer on the cavity or the acoustic mirror oscillates, producing parallel to the thickness longitudinal waves in the direction and clutter propagating in the direction perpendicular to the thickness (transverse direction). Under the alternating voltage of a specific frequency, the suspended film will resonate to achieve special electrical characteristics.

technical problem

In the prior art, although the main mode at resonance is the longitudinal wave mode, some spurious modes are still formed along with the longitudinal wave excitation. These spurious 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; or they can be laterally propagating clutter, causing energy leakage and increasing the filter insertion loss. , reducing the quality factor (Q) of the device.

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

technical solutions

The purpose of the present invention is to provide a resonator structure that reduces energy loss, increases the Q value of the device, and reduces insertion loss.

In order to achieve the above object, the present invention provides a resonator,

include:

substrate;

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

a piezoelectric layer formed on 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 resonance Area;

space, formed in the resonance region;

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

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 arranged between the substrate and the bottom electrode, and the acoustic mirror includes at least one layer of a first acoustic impedance material and at least one layer of a second acoustic impedance material, 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 on the substrate, and 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 disposed opposite to the first surface, and the space is spaced apart from the third surface.

Preferably, the top electrode includes a fourth surface disposed opposite to the second surface, and the space is spaced 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, and silicon nitride.

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

beneficial effect

The present invention also provides a method for preparing the above-mentioned resonator, the method comprising the following steps:

provide a substrate;

depositing on the substrate to form a bottom electrode;

A piezoelectric layer is formed by depositing a side of the bottom electrode away from the substrate;

After depositing the sacrificial material on the side of the piezoelectric layer away from the bottom electrode, pattern it to form a first sacrificial layer;

A top electrode is formed by depositing a side of the first sacrificial layer and the piezoelectric layer away from the bottom electrode;

The resonator is obtained by releasing the space formed by the first sacrificial layer.

The present invention also provides another preparation method of the resonator as described above, the method comprising the following steps:

provide a substrate;

etching the substrate to form a cavity, filling the cavity with a first sacrificial layer, and etching the first sacrificial layer to form a depression;

depositing a bottom electrode on the substrate and the first sacrificial layer;

The bottom electrode is formed in the recess to enclose a formation space, and the space is filled with sacrificial material to form a second sacrificial layer;

A piezoelectric layer is formed by depositing a side of the second sacrificial layer and the bottom electrode away from the substrate;

A top electrode is formed by depositing a side of the piezoelectric layer away from the bottom electrode;

The resonator is obtained by releasing the first sacrificial layer and the second sacrificial layer.

The present invention 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 region of the top electrode, the piezoelectric layer and the bottom electrode is a resonance region;

space, formed in the resonance region;

The piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface opposite 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 in the substrate.

Preferably, an acoustic mirror is arranged between the substrate and the bottom electrode, and the acoustic mirror includes at least one layer of a first acoustic impedance material and at least one layer of a second acoustic impedance material, 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 on the substrate, and 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, and silicon nitride.

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

The present invention also provides a method for preparing the above-mentioned resonator, the method comprising the following steps:

provide a substrate;

depositing on the substrate to form a bottom electrode;

A piezoelectric layer is deposited on the side of the bottom electrode away from the substrate, the piezoelectric layer is etched to form a space on the side away from the bottom electrode, and a sacrificial material is filled in the space to form a first a sacrificial layer;

A top electrode is formed by depositing a side of the first sacrificial layer and the piezoelectric layer away from the bottom electrode;

The first sacrificial layer is released, thereby obtaining the resonator.

The present invention also provides another preparation method of the resonator as described above, the method comprising the following steps:

provide a substrate;

depositing on the substrate to form a bottom electrode;

After depositing the sacrificial material on the side of the bottom electrode away from the substrate, pattern it to form a first sacrificial layer;

A piezoelectric layer is formed by depositing a side of the first sacrificial layer and the bottom electrode away from the substrate;

A top electrode is formed by depositing a side of the piezoelectric layer away from the bottom electrode;

The resonator is obtained by releasing the space formed by the first sacrificial layer.

Compared with the related art, in the resonator of the present invention, the overlapping region of the top electrode, the piezoelectric layer and the bottom electrode is a resonance region, and the resonator further includes a space formed in the resonance region , 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. or the piezoelectric layer includes a bottom surface facing the bottom electrode and a bottom surface disposed opposite the bottom surface and facing the top 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; that is, through the above-mentioned structural arrangement, the space is introduced into the resonance area, and the lateral propagation Most of the clutter will be reflected back to the resonance area, reducing the clutter propagating outside the resonance area, so that most of the energy is confined in the resonance area, reducing energy loss, improving the Q value of the resonator, and reducing insertion loss. At the same time, after applying a high-frequency voltage, the main mode and parasitic mode will be formed in the two resonance regions separated by space. No wave excitation; therefore counter-propagating spurious modes in the two resonant regions separated by space cancel each other out, reducing the propagation of transverse clutter and the formation of transverse standing waves in the entire resonant region; by adjusting the two resonant regions And the size of the space area, it can selectively eliminate or reduce the spurious peaks 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 illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, under the premise of no creative work, other drawings can also be obtained from these drawings, wherein:

1 is a schematic structural diagram of a resonator according to an embodiment of the present invention;

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

3 is a cross-sectional view of an embodiment of the present invention provided with an acoustic mirror;

4 is an exploded schematic view of a resonator according to an embodiment of the present invention;

5 is another exploded schematic view of a resonator according to an embodiment of the present invention;

6 is a cross-sectional view of a second resonator according to Embodiment 2 of the present invention;

7 is a cross-sectional view of a third resonator according to an embodiment of the present invention;

8 is a cross-sectional view of a fourth resonator according to an embodiment of the present invention;

9 is a cross-sectional view of a fifth resonator according to Embodiment 5 of the present invention;

Fig. 10 is the preparation process of the resonator in the first embodiment of the present invention;

11 is a schematic structural diagram of the resonator preparation process in Embodiment 1 of the present invention;

Fig. 12 is the preparation process of the resonator in the second embodiment of the present invention;

13 is a schematic structural diagram of the resonator preparation process in Embodiment 2 of the present invention;

Fig. 14 is the preparation process of the resonator in the third embodiment of the present invention;

15 is a schematic structural diagram of the resonator preparation process in Embodiment 3 of the present invention;

Fig. 16 is the preparation process of the resonator in the fourth embodiment of the present invention;

FIG. 17 is a schematic structural diagram of the resonator preparation process in Embodiment 4 of the present invention.

Embodiments of the present invention

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

1-5, 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 region of the piezoelectric layer 3 and the bottom electrode 2 is a resonance region 5; the resonator 100 further includes a space 10 formed in the resonance region 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 second surface 4a extends away from the piezoelectric layer 3, and the space 10 is spaced 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 in the substrate 1. Of course, in other embodiments, The cavity 110 may not be provided, and is specifically designed according to actual requirements.

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 first acoustic impedance material layer 12 a and at least one layer 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 sequentially overlapped on the substrate 1', and the first The number of layers of an acoustic impedance material layer 12a and the second acoustic impedance material layer 12b are equal; 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 may be a high acoustic impedance material such as tungsten, molybdenum, etc., and the second acoustic impedance material layer 12b may be a low acoustic impedance material such as silicon dioxide, silicon nitride, aluminum nitride, etc. . 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 extend To or not to extend to the side surface of the top electrode 4, the setting can be selected according to the actual product design, which will not be described in detail below.

The orthographic projection of the top electrode 4 to the substrate 1 after removing the part connected to the external circuit is an apodized hexagon. 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.

As shown in FIG. 2 , the resonance region 5 includes a first resonance region 51 surrounded by the space 10 , a second resonance region 52 corresponding to the space 10 , and a third resonance region 53 outside the space 10 .

After applying the high frequency voltage, the main mode and the spurious mode will be formed in the first resonance region 51 and the third resonance region 53, while in the second resonance region 52, the piezoelectric layer 3 and the top are separated by the sealed space 10. Electrode 4, so the excitation of waves will not be generated in the second resonance region 52; as shown by the arrows in the upper part of FIG. 5. The propagation of transverse clutter and the formation of transverse standing waves; by adjusting the size of the first resonance region 51, the second resonance region 52 and the third resonance 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. . The bottom electrode 2 and the top electrode 4 are made of one or more materials such as molybdenum, tungsten, platinum, aluminum, etc. 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.

This embodiment also provides a method for manufacturing the resonator 100, as shown in FIG. 10 and FIG. 11, the method includes the following steps:

S1, providing the substrate 1, as shown in Figure 11a;

S2, depositing a bottom electrode 2 on the substrate 1, as shown in FIG. 11b;

S3, a piezoelectric layer 3 is deposited on the side of the bottom electrode 2 away from the substrate 1, as shown in FIG. 11c;

S4, the sacrificial material a is deposited on the side of the piezoelectric layer 3 away from the bottom electrode 1 and then patterned to form a first sacrificial layer 10a, as shown in FIG. 11d ;

S5, depositing a top electrode 4 on the side of the first sacrificial layer 10a and the piezoelectric layer 3 away from the bottom electrode 1, as shown in FIG. 11e;

S6, releasing the first sacrificial layer 10a to form a space 10, thereby obtaining the resonator 100, as shown in FIG. 11f.

In the resonator 100 produced according to the above steps, the space 10 extends away from the piezoelectric layer 3 from the second surface 4a, and the space 10 causes the laterally propagated clutter to be mostly reflected back to the resonance region, Reduce the clutter propagating outside the resonance area, so that most of the energy is confined in the resonance area, reducing energy loss, improving the Q value of the resonator, and reducing insertion loss.

Embodiment 2

Referring to FIG. 6 , the present embodiment provides a resonator 200 whose structure is substantially the same as that of the resonator 100 in the first embodiment. The difference lies in that the bottom electrode 22 includes a first surface 22 a and a The surface 22a is opposite to the third surface 22b, 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 3 and is The space 102 is spaced apart from the third surface 22b.

This embodiment also provides a method for manufacturing the resonator 200, as shown in FIG. 12 and FIG. 13, the method includes the following steps:

S11, providing the substrate 12, etching the substrate 12 to form a cavity 12c, filling the cavity 12c with a first sacrificial layer 12d, and etching the first sacrificial layer 12d to form a depression; as shown in FIG. 13a;

S21, depositing a bottom electrode 22 on the substrate 12 and the first sacrificial layer 12d, as shown in FIG. 13b;

S31 , the area where the bottom electrode 22 is formed in the recess surrounds a space 102 , and the space is filled with a sacrificial material 2 a to form a second sacrificial layer 102 a , as shown in FIG. 13 c ;

S41, depositing a piezoelectric layer 32 on the side of the second sacrificial layer 102a and the bottom electrode 22 away from the substrate 12, as shown in FIG. 13d;

S51, depositing a top electrode 42 on the side of the piezoelectric layer 32 away from the bottom electrode 22, as shown in FIG. 13e;

S61, releasing the first sacrificial layer 12d and the second sacrificial layer 102a, thereby obtaining the resonator 200, as shown in FIG. 13f.

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

Embodiment 3

Referring to FIG. 7 , the present embodiment provides a resonator 300 whose structure is substantially the same as that of the resonator 100 in the first embodiment, except that the piezoelectric layer 33 includes a bottom surface facing the bottom electrode 23 . 332 and the top surface 331 opposite 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 the piezoelectric Layer 33.

This embodiment also provides a method for manufacturing the resonator 300, as shown in FIG. 14 and FIG. 15, the method includes the following steps:

S12, providing the substrate 13, as shown in FIG. 15a;

S22, depositing a bottom electrode 23 on the substrate 13, as shown in FIG. 15b;

S32, deposit and form the piezoelectric layer 33 on the side of the bottom electrode 23 away from the substrate 13, etch the piezoelectric layer 33 to form a space 103 on the side of the bottom electrode 23 away from the bottom electrode 23, and The space is filled with a sacrificial material 3a to form a first sacrificial layer 103a, as shown in FIG. 15c;

S42, depositing a top electrode 43 on the side of the first sacrificial layer 103a and the piezoelectric layer 33 away from the bottom electrode 23, as shown in FIG. 15d;

S52, releasing the first sacrificial layer 103a, thereby obtaining the resonator 300, as shown in FIG. 15e.

Embodiment 4

Referring to FIG. 8 , the present embodiment provides a resonator 400 whose structure is substantially the same as that of the resonator 100 in the first embodiment, 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 penetrate the Piezoelectric layer 34 .

This embodiment also provides a method for manufacturing the resonator 400, as shown in FIG. 16 and FIG. 17, the method includes the following steps:

S13, providing the substrate 14, as shown in FIG. 17a;

S23, depositing a bottom electrode 24 on the substrate 14, as shown in FIG. 17b;

S33, after depositing the sacrificial material 4a on the side of the bottom electrode 24 away from the substrate 14, pattern it to form a first sacrificial layer 104a, as shown in FIG. 17c;

S43, depositing a piezoelectric layer 34 on the side of the first sacrificial layer 104a and the bottom electrode 24 away from the substrate 14, as shown in FIG. 17d;

S53, depositing a top electrode 44 on the side of the piezoelectric layer 34 away from the bottom electrode 24, as shown in FIG. 17e;

S63, releasing the first sacrificial layer 104a to form a space 104, thereby obtaining the resonator 400, as shown in FIG. 17f.

Embodiment 5

Referring to FIG. 9 , the present embodiment provides a resonator 500 whose structure is substantially the same as that of the resonator 300 in the third embodiment, except that the space 105 extends from the top surface 351 of the piezoelectric layer to The bottom surface 352, that is, the space 105, reaches the maximum, and the energy loss is less, the Q value of the resonator is improved, and the insertion loss is reduced. The manufacturing method of the resonator 500 of this embodiment is the same as the manufacturing method of the resonator 300 of the third embodiment, except that when the piezoelectric layer is etched, the piezoelectric layer is etched through, and the first sacrificial layer and the piezoelectric layer are filled. The height is flush.

Compared with the related art, in the resonator of the present invention, the overlapping region of the top electrode, the piezoelectric layer and the bottom electrode is a resonance region, and the resonator further includes a space formed in the resonance region , 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. or the piezoelectric layer includes a bottom surface facing the bottom electrode and a bottom surface disposed opposite the bottom surface and facing the top 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; that is, through the above-mentioned structural arrangement, the space is introduced into the resonance area, and the lateral propagation Most of the clutter will be reflected back to the resonance area, reducing the clutter propagating outside the resonance area, so that most of the energy is confined in the resonance area, reducing energy loss, improving the Q value of the resonator, and reducing insertion loss. At the same time, after applying a high-frequency voltage, the main mode and parasitic mode will be formed in the two resonance regions separated by space. No wave excitation; therefore counter-propagating spurious modes in the two resonant regions separated by space cancel each other out, reducing the propagation of transverse clutter and the formation of transverse standing waves in the entire resonant region; by adjusting the two resonant regions And the size of the space area, it can selectively eliminate or reduce the spurious peaks of a specific frequency, so as to reduce the ripple in the passband, reduce the insertion loss, and improve the performance of the device.

The above are only the embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present invention, but these belong to the present invention. scope of protection.

 

Claims (12)

1. A resonator, characterized in that it comprises:

   substrate;

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

   a piezoelectric layer formed on 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 resonance Area;

   space, formed in the resonance region;

   The space extends from the first surface in a direction away from the piezoelectric layer and/or extends in a direction away from the piezoelectric layer from the second surface.
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 comprises at least one layer of a first acoustic impedance material and at least one layer of A second acoustic impedance material layer, at least one layer of the first acoustic impedance material layer and at least one layer of the second acoustic impedance material layer are sequentially overlapped on the substrate, and the first acoustic impedance material layer The number of 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 of claim 1, wherein the bottom electrode comprises a third surface disposed opposite to the first surface, and the space is spaced apart from the third surface.
6. The resonator of claim 1, wherein the top electrode comprises a fourth surface disposed opposite to the second surface, and the space is spaced apart from the fourth surface.
7. The resonator of claim 6, wherein the top electrode includes a side surface connecting the second surface and the fourth surface, the space extending to the side surface.
8. The resonator according to claim 1, wherein the space is filled with one or more materials such as air, silicon dioxide, silicon, and silicon nitride.
9. The resonator according to claim 1, wherein the bottom electrode and the top electrode can be made of one or more materials such as molybdenum, tungsten, platinum, and aluminum, and the piezoelectric layer can be made of nitrogen It is made of one or more piezoelectric materials such as aluminum, scandium-doped aluminum nitride, zinc oxide, and PZT.
10. A method for preparing a resonator as claimed in any one of claims 1-9, wherein the method comprises the following steps:

    provide a substrate;

    depositing on the substrate to form a bottom electrode;

    A piezoelectric layer is formed by depositing a side of the bottom electrode away from the substrate;

    After depositing the sacrificial material on the side of the piezoelectric layer away from the bottom electrode, pattern it to form a first sacrificial layer;

    A top electrode is formed by depositing a side of the first sacrificial layer and the piezoelectric layer away from the bottom electrode;

    The resonator is obtained by releasing the space formed by the first sacrificial layer.
11. A method for preparing a resonator as claimed in any one of claims 1-9, wherein the method comprises the following steps:

    provide a substrate;

    etching the substrate to form a cavity, filling the cavity with a first sacrificial layer, and etching the first sacrificial layer to form a depression;

    depositing a bottom electrode on the substrate and the first sacrificial layer;

    The bottom electrode is formed in the recess to enclose a formation space, and the space is filled with sacrificial material to form a second sacrificial layer;

    A piezoelectric layer is formed by depositing a side of the second sacrificial layer and the bottom electrode away from the substrate;

    A top electrode is formed by depositing a side of the piezoelectric layer away from the bottom electrode;

    The resonator is obtained by releasing the first sacrificial layer and the second sacrificial layer.
12. A resonator, characterized in that it comprises:

    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 region of the top electrode, the piezoelectric layer and the bottom electrode is a resonance region;

    space, formed in the resonance region;

    The piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface opposite 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.

    13. The resonator according to claim 12, wherein a cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or in the substrate.

    14. The resonator according to claim 12, wherein an acoustic mirror is provided between the substrate and the bottom electrode, and the acoustic mirror comprises at least one layer of a first acoustic impedance material layer and at least one layer of a first acoustic impedance material layer. A layer of a second acoustic impedance material layer, at least one layer of the first acoustic impedance material layer and at least one layer of the second acoustic impedance material layer are sequentially overlapped on the substrate, and the first acoustic impedance material layer is disposed on the substrate. The number of layers of impedance material is equal to that of the second layer of acoustic impedance material.

    15. The resonator of claim 14, wherein the acoustic impedance value of the first acoustic impedance material is greater than the acoustic impedance value of the second acoustic impedance material.

    16. The resonator of claim 12, wherein the space extends from the bottom surface of the piezoelectric layer to the top surface.

    17. The resonator of claim 12, wherein the space is filled with one or more materials such as air, silicon dioxide, silicon, and silicon nitride.

    18. The resonator according to claim 12, wherein the bottom electrode and the top electrode can be made of one or more materials such as molybdenum, tungsten, platinum, aluminum, and the like, and the piezoelectric layer can be It is made of one or more piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, PZT, etc.

    19. a preparation method of the resonator as described in any one of claim 12-18, is characterized in that, this method comprises the following steps:

    provide a substrate;

    depositing on the substrate to form a bottom electrode;

    A piezoelectric layer is deposited on the side of the bottom electrode away from the substrate, the piezoelectric layer is etched to form a space on the side away from the bottom electrode, and a sacrificial material is filled in the space to form a first a sacrificial layer;

    A top electrode is formed by depositing a side of the first sacrificial layer and the piezoelectric layer away from the bottom electrode;

    The first sacrificial layer is released, thereby obtaining the resonator.

    20. the preparation method of the resonator as described in any one of claim 12-18, it is characterised in that the method comprises the following steps:

    provide a substrate;

    depositing on the substrate to form a bottom electrode;

    After depositing the sacrificial material on the side of the bottom electrode away from the substrate, pattern it to form a first sacrificial layer;

    A piezoelectric layer is formed by depositing a side of the first sacrificial layer and the bottom electrode away from the substrate;

    A top electrode is formed by depositing a side of the piezoelectric layer away from the bottom electrode;

    The resonator is obtained by releasing the space formed by the first sacrificial layer.