WO2023082186A1

WO2023082186A1 - Resonator and preparation method therefor, and filter

Info

Publication number: WO2023082186A1
Application number: PCT/CN2021/130381
Authority: WO
Inventors: 黄裕霖; 张本锋; 李昕熠; 秦旭东; 高宗智
Original assignee: 华为技术有限公司
Priority date: 2021-11-12
Filing date: 2021-11-12
Publication date: 2023-05-19

Abstract

The embodiments of the present application relate to the technical field of wireless communications. Provided are a resonator and a preparation method therefor, and a filter, which can improve a quality factor of a resonator by means of reducing the propagation speed of a transverse sound wave. The resonator comprises a piezoelectric substrate; and an input bus bar, an output bus bar, a plurality of first interdigital electrodes electrically connected to the input bus bar and a plurality of second interdigital electrodes electrically connected to the output bus bar, which are all arranged on an upper surface of the piezoelectric substrate. The resonator comprises an input bus area, an output bus area and a transduction area. The input bus bar is located in the input bus area, the output bus bar is located in the output bus area, and the plurality of first interdigital electrodes and the plurality of second interdigital electrodes are located in the transduction area. A part of the upper surface of the piezoelectric substrate that is located in the transduction area is not on the same plane as parts thereof that are located in the input bus area and the output bus area.

Description

Resonator and its preparation method, filter

technical field

The present application relates to the technical field of wireless communication, in particular to a resonator, a manufacturing method thereof, and a filter.

Background technique

With the development of wireless communication technology, the vigorous development of the intelligent terminal market has been driven, and the filter plays a vital role in the development of wireless communication technology. Acoustic filters are widely used in smart terminals due to their small size and light weight.

Acoustic wave filters mainly include surface acoustic wave (surface acoustic wave, SAW) filter, bulk acoustic wave (bulk acoustic wave, BAW) surface acoustic wave filter, etc. Among them, the SAW filter includes a resonator, and the quality factor (Q value) of the resonator directly affects the insertion loss of the SAW filter. Therefore, there are higher requirements on the operating frequency and Q value of the resonator.

Contents of the invention

In order to solve the above technical problems, the present application provides a resonator and its preparation method, and a filter, which can improve the quality factor of the resonator by reducing the propagation speed of the transverse sound wave.

In a first aspect, the present application provides a resonator, which includes a piezoelectric substrate and interdigital electrodes disposed on the piezoelectric substrate. The resonator includes an input confluence area, a transduction area and an output confluence area. The interdigital transducer includes an input bus bar, an output bus bar, a plurality of first interdigital electrodes electrically connected to the input bus bar, and a plurality of second interdigital electrodes electrically connected to the output bus bar; the input bus bar is located at the input In the confluence area, the output bus bar is located in the output confluence area, and the plurality of first interdigital electrodes and the plurality of second interdigital electrodes are located in the transduction area. Wherein, on the upper surface of the piezoelectric substrate, the part located in the transducing area is not in the same plane as the part located in the input confluence area and the output confluence area.

In this application, since the plurality of first interdigital electrodes are electrically connected to the input bus bar, and on the upper surface of the piezoelectric substrate, the part located in the transducing area and the part located in the input bus area are not on the same plane, that is, the first surface The part from the input confluence area to the transducing area has a step. Therefore, along the second direction, there is a discontinuity between the plurality of first interdigital electrodes and the input bus bar, thereby resulting in discontinuity of the transverse acoustic wave propagating along the second direction. By making the transverse sound wave discontinuously propagate in the second direction, the propagation speed of the transverse sound wave along the second direction can be reduced, thereby effectively suppressing the transverse sound wave, improving the Q value of the resonator, and then increasing the operating frequency of the SAW filter and reducing the SAW filter The insertion loss of the filter, and at the same time improve the problem that the transverse sound wave affects the in-band ripple and passband performance of the SAW filter.

Similarly, since a plurality of second interdigital electrodes are electrically connected to the output bus bar, the part located in the transducing area and the part located in the output bus area on the upper surface of the piezoelectric substrate are not in the same plane, that is, the first surface The part from the output confluence area to the transduction area has a step. Therefore, along the second direction, there is a discontinuity between the plurality of second interdigital electrodes and the output bus bar, thereby resulting in discontinuity of the transverse acoustic wave propagating along the second direction. By making the transverse sound wave discontinuously propagate in the second direction, the propagation speed of the transverse sound wave along the second direction can be reduced, thereby effectively suppressing the transverse sound wave, improving the Q value of the resonator, and then increasing the operating frequency of the SAW filter and reducing the SAW filter The insertion loss of the filter, and at the same time improve the problem that the transverse sound wave affects the in-band ripple and passband performance of the SAW filter.

In some possible implementation manners, the thickness of the portion of the piezoelectric substrate located in the transducing area is greater than the thickness of the portion located in the input confluence area and the output confluence area.

Specifically, the above-mentioned piezoelectric substrate includes a first piezoelectric substrate; the part of the first piezoelectric substrate located in the input confluence area is provided with a first groove, and the part of the first piezoelectric substrate located in the output confluence area is provided with a second recess. groove. The depth range of the first groove and the second groove can be 0.001λ˜1λ, λ represents the wavelength of the longitudinal sound wave generated by the resonator, and the longitudinal sound wave propagates along the vertical direction from the first interdigitated electrode to the second interdigitated electrode. Since the surface of the piezoelectric substrate 10 without grooves is flatter than the surface of the piezoelectric substrate with grooves. Therefore, by opening the first groove in the input confluence area and opening the second groove in the output confluence area, it is possible to avoid the part of the piezoelectric layer located in the transduction area caused by the process of opening the first groove and the second groove. The surface is not flat enough, thereby affecting the transduction effect of the plurality of first interdigital electrodes and the plurality of second interdigital electrodes. Moreover, compared with the following situation where the piezoelectric substrate includes the first piezoelectric substrate and the second piezoelectric substrate, the embodiment of the present application can not only omit the process of depositing the second piezoelectric substrate, but also reduce the total thickness of the resonator.

Alternatively, the above-mentioned piezoelectric substrate includes a first piezoelectric substrate and a second piezoelectric substrate disposed between the first piezoelectric substrate and the interdigital transducer; the first piezoelectric substrate is at least located in the input confluence region, the transducer region and The output confluence area; the second piezoelectric substrate is located in the transducing area. By forming the second piezoelectric substrate between the first piezoelectric substrate and the interdigital transducers, the flatness of the portion of the piezoelectric substrate located in the transducing region can be ensured, thereby ensuring a plurality of first interdigital electrodes and a plurality of piezoelectric substrates. The transducing effect of the second interdigitated electrode.

Of course, the thickness of the part of the piezoelectric substrate located in the transducing region can also be realized in other ways, which are respectively greater than the thicknesses of the parts located in the input confluence region and the output confluence region, so that the upper surface of the piezoelectric substrate is located in the transduction region The part located in the input confluence area and the output confluence area are not on the same plane, which is not limited in this embodiment of the present application.

In some possible implementation manners, the thickness of the portion of the piezoelectric substrate located in the transducing area is smaller than the thickness of the portion located in the input confluence area and the output confluence area.

Specifically, the above-mentioned piezoelectric substrate includes a first piezoelectric substrate. The part of the first piezoelectric substrate located in the transducing region is provided with a third groove, so that the thickness of the part of the piezoelectric substrate located in the transducing region is smaller than the thicknesses of the parts located in the input confluence region and the output confluence region.

Alternatively, the piezoelectric substrate includes a first piezoelectric substrate and a second piezoelectric substrate disposed between the first piezoelectric substrate and the IDT. The first piezoelectric substrate is at least located in the input confluence area, the transduction area and the output confluence area; the second piezoelectric substrate is located in the input confluence area and the output confluence area. By arranging a plurality of first interdigital electrodes and a plurality of second interdigital electrodes on the first piezoelectric substrate, the flatness of the portion of the piezoelectric substrate located in the transducing region can be ensured, thereby ensuring that the plurality of first interdigital electrodes The transducing effect of the electrode and the plurality of second interdigitated electrodes.

In some possible implementation manners, the thickness of the piezoelectric substrate at the input confluence region is the same as the thickness of the piezoelectric substrate at the output confluence region. On the one hand, the consistency of the structure of the first interdigital electrode and the second interdigital electrode can be ensured, so that the transverse sound wave can pass through the discontinuous part between the first interdigital electrode and the input bus bar, and between the second interdigital electrode and the output bus bar. The discontinuous part of the bus bar enters the piston working mode at the same time. It can also be said that the transverse sound wave enters the piston working mode at the step of the input confluence area and the transduction area, and at the step of the output confluence area and the transduction area, thereby Better suppression of transverse acoustic waves; on the other hand, in the case where the first piezoelectric substrate includes the first groove and the second groove, the same photolithography process can be used to simultaneously etch the first groove and the second groove. The groove simplifies the preparation process of the piezoelectric substrate.

In some possible implementations, the edge of the input confluence area facing the output confluence area has a first distance from the edge of the input bus bar facing the output bus bar; the output confluence area faces the edge of the input confluence area, and the The edges of the bars have a second spacing. Thereby ensuring mutual insulation between multiple first interdigital electrodes and multiple second interdigital electrodes, avoiding short circuit between multiple first interdigital electrodes and multiple second interdigital electrodes through the output bus bar, avoiding multiple second forked electrodes The finger electrodes are shorted to the plurality of first interdigit electrodes through the input bus bar. Optionally, the size range of the first distance and the second distance may be 10%λ˜5λ.

On this basis, a plurality of first interdigitated electrodes face the edge of the output bus bar, and are flush with the edge of the output confluence area toward the input confluence area; multiple second interdigital electrodes face the edge of the input bus bar, and are flush with the edge of the input confluence area. flush with the edge towards the output manifold. A plurality of first interdigital electrodes and a plurality of second interdigital electrodes can be continuously arranged in the transducing region along the second direction, so as to avoid additional reflection of the surface acoustic wave at the edge.

Alternatively, multiple first interdigital electrodes extend from the input confluence region to the output confluence region, and multiple second interdigital electrodes extend from the output confluence region to the input confluence region, so as to improve the design freedom of the resonator.

In some other possible implementation manners, the plurality of first interdigitated electrodes faces the edge of the output bus bar, and has a distance from the edge of the output bus area toward the input bus bar; the plurality of second interdigitated electrodes faces the edge of the input bus bar, There is a distance from the edge of the input catchment area towards the output catchment area. Thereby, the degree of freedom in designing the resonator is improved.

In a second aspect, the present application provides a filter, which includes one or more resonators as described in the first aspect.

In the third aspect, a method for preparing a resonator is provided. The resonator is divided into an input bus bar area, a transduction area, and an output bus bar area; the method includes: forming a piezoelectric substrate; forming an interdigitated switch on the piezoelectric substrate energy device; the interdigital transducer includes an input bus bar, an output bus bar, a plurality of first interdigital electrodes electrically connected to the input bus bar, and a plurality of second interdigital electrodes electrically connected to the output bus bar; the input bus bar The bar is located in the input confluence area, the output bus bar is located in the output confluence area, and a plurality of first interdigital electrodes and a plurality of second interdigital electrodes are located in the transducing area; wherein, in the upper surface of the piezoelectric substrate, the part located in the transducing area Not on the same plane as the part located in the inlet and outlet catchment areas.

In some possible implementation manners, forming the piezoelectric substrate includes: forming a first piezoelectric film; using a photolithography process, etching the part of the first piezoelectric film located at the input confluence area and the output confluence area to form the first piezoelectric film A piezoelectric substrate; the first piezoelectric substrate includes a first groove located in the input confluence area and a second groove located in the output confluence area.

In some possible implementation manners, forming the piezoelectric substrate includes: sequentially forming a stacked first piezoelectric substrate and a second piezoelectric film, the first piezoelectric substrate is at least located in the input confluence region, the transducer region and the output confluence region ; Using a photolithography process, etch the part of the second piezoelectric film located in the input confluence area and the output confluence area to form a second piezoelectric substrate; the second piezoelectric substrate is located in the transduction area.

In some possible implementation manners, forming the piezoelectric substrate includes: forming a first piezoelectric film; using a photolithography process, etching the part of the first piezoelectric film located in the transducing region to form the first piezoelectric substrate ; The first piezoelectric substrate includes a third groove located in the transducing area.

In some possible implementation manners, forming the piezoelectric substrate includes: sequentially forming a first substrate and a second piezoelectric film that are laminated, and the first piezoelectric substrate is at least located in the input confluence region, the transducer region, and the output confluence region; The photolithography process is to etch the part of the second piezoelectric film located in the transducing region to form a second piezoelectric substrate; the second piezoelectric substrate is located in the input confluence region and the output confluence region.

In some possible implementation modes, forming the interdigital transducer on the piezoelectric substrate includes: forming a photoresist on the piezoelectric substrate, exposing the photoresist, and obtaining a photoresist pattern after development; The pattern exposes the area where the interdigital transducer to be formed is located; an electrode film is formed on the side of the photoresist pattern away from the piezoelectric substrate; the photoresist pattern is peeled off to obtain the interdigital transducer from the electrode film. The input bus bar, output bus bar, multiple first interdigital electrodes and multiple second interdigital electrodes of the interdigital transducer can be formed through only one semiconductor process, which simplifies the process steps of preparing the resonator and saves the mask. Reduce preparation costs.

The third aspect and any implementation manner of the third aspect correspond to the first aspect and any implementation manner of the first aspect respectively. For the technical effects corresponding to the third aspect and any one of the implementation manners of the third aspect, refer to the above-mentioned first aspect and the technical effects corresponding to any one of the implementation manners of the first aspect, which will not be repeated here.

Description of drawings

Fig. 1 is the circuit connection diagram of the filter that the embodiment of the present application provides;

FIG. 2 is a schematic structural diagram of a resonator provided in an embodiment of the present application;

FIG. 3 is a working principle diagram of the filter provided by the embodiment of the present application;

Fig. 4 is the conductance diagram and the admittance diagram of the surface acoustic wave generated by the resonator provided by the embodiment of the present application;

FIG. 5 is a top view of a resonator provided in an embodiment of the present application;

Figure 6a is a side view of a resonator corresponding to the top view shown in Figure 5;

Fig. 6b is a side view of another resonator corresponding to the top view shown in Fig. 5;

Fig. 7a is a side view of another resonator corresponding to the top view shown in Fig. 5;

Fig. 7b is a side view of another resonator corresponding to the top view shown in Fig. 5;

Fig. 8a is a side view of another resonator corresponding to the top view shown in Fig. 5;

Fig. 8b is a side view of another resonator corresponding to the top view shown in Fig. 5;

Fig. 9a is a side view of another resonator corresponding to the top view shown in Fig. 5;

Fig. 9b is a side view of another resonator corresponding to the top view shown in Fig. 5;

Figure 10a is the admittance diagram of the resonator corresponding to the first groove and the second groove of different depths;

Figure 10b is the conductance diagram of the resonator corresponding to the first groove and the second groove with different depths

Fig. 11 is another top view of the resonator provided in the embodiment of the present application;

Fig. 12 is a side view of another resonator corresponding to the top view shown in Fig. 11;

Fig. 13 is another top view of the resonator provided by the embodiment of the present application;

Fig. 14a is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 14b is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 15a is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 15b is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 16a is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 16b is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 17a is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 17b is a side view of another resonator corresponding to the top view shown in Fig. 13;

Fig. 18 is another top view of the resonator provided in the embodiment of the present application;

FIG. 19 is a flow chart of the preparation of the resonator provided in the embodiment of the present application;

Fig. 20a is a diagram of a preparation process of the piezoelectric substrate provided in the embodiment of the present application;

Fig. 20b is another diagram of the preparation process of the piezoelectric substrate provided in the embodiment of the present application;

Fig. 20c is another diagram of the preparation process of the piezoelectric substrate provided in the embodiment of the present application;

Fig. 21a is another preparation process diagram of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 21b is a diagram of another preparation process of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 21c is another diagram of the preparation process of the piezoelectric substrate provided in the embodiment of the present application;

Fig. 22a is another preparation process diagram of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 22b is another diagram of the preparation process of the piezoelectric substrate provided in the embodiment of the present application;

Figure 22c is another diagram of the preparation process of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 23a is another preparation process diagram of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 23b is another diagram of the preparation process of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 23c is another diagram of the preparation process of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 24 is a flow chart of the preparation of the interdigital transducer provided by the embodiment of the present application;

Fig. 25a is another preparation process diagram of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 25b is another diagram of the preparation process of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 25c is another diagram of the preparation process of the piezoelectric substrate provided by the embodiment of the present application;

Fig. 25d is a diagram of another preparation process of the piezoelectric substrate provided by the embodiment of the present application.

Reference signs:

100-filter; 10-piezoelectric substrate; 101-piezoelectric layer; 102-functional layer; 103-high sound velocity layer; 104-support layer; 11-first piezoelectric substrate; 111-first piezoelectric film; 12 - second piezoelectric substrate; 121 - second piezoelectric film; 20 - electrode film; 21 - input bus bar; 22 - output bus bar; 23 - first interdigitated electrode; 24 - second interdigitated electrode; 31 - The first photoresist; 311-the first photoresist pattern; 32-the second photoresist; 321-the second photoresist pattern; 33-the third photoresist; 331-the third photoresist pattern; 34 - fourth photoresist; 341 - fourth photoresist pattern; 35 - fifth photoresist; 351 - fifth photoresist pattern.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

The term "and/or" in this article is just an association relationship describing associated objects, which means that there can be three relationships, for example, A and/or B can mean: A exists alone, A and B exist simultaneously, and there exists alone B these three situations.

The terms "first" and "second" in the description and claims of the embodiments of the present application are used to distinguish different objects, rather than to describe a specific order of objects. For example, the first target object, the second target object, etc. are used to distinguish different target objects, rather than describing a specific order of the target objects.

In the embodiments of the present application, words such as "exemplary" or "for example" are used as examples, illustrations or illustrations. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of the present application shall not be interpreted as being more preferred or more advantageous than other embodiments or design schemes. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete manner.

In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more. For example, multiple processing units refer to two or more processing units; multiple systems refer to two or more systems.

As shown in FIG. 1 , the embodiment of the present application provides a filter 100, and the filter 100 may be a SAW filter. The SAW filter may include an input terminal Input, an output terminal Output, and one or more series resonators (S1, S2, S3) coupled between the input terminal Input and the output terminal Output and/or one or more parallel resonators Resonators (P1, P2, P3). As shown in FIG. 2 , the series resonator and the parallel resonator may include a piezoelectric substrate 10 and an interdigital transducer (interdigital transducer, IDT) disposed on the upper surface of the piezoelectric substrate 10 .

It should be noted here that “on” in the upper surface of the piezoelectric substrate 10 has nothing to do with the installation position of the piezoelectric substrate 10, as long as the upper surface of the piezoelectric substrate 10 faces the interdigital transducer in the piezoelectric substrate 10 surface.

Please continue to refer to FIG. 2 , the piezoelectric substrate 10 may include a piezoelectric layer 101 . On this basis, the piezoelectric substrate 10 may further include at least one of a functional layer 102 , a high-sonic layer 103 and a supporting layer 104 . Along the direction from the IDT to the piezoelectric substrate 10 , the functional layer 102 , the high-sonic layer 103 and the support layer 104 are sequentially stacked on the side of the piezoelectric layer 101 away from the IDT. The material of the piezoelectric layer 101 may include at least one of lithium niobate, lithium tantalate, and aluminum nitride, and the material of the functional layer 102 may include at least one of silicon dioxide, silicon oxynitride, and tantalum pentoxide, The material of the high-sonic layer 103 may include at least one of tungsten, diamond, aluminum oxide, silicon carbide, silicon nitride, and polysilicon.

For the convenience of description, the piezoelectric substrate 10 includes a piezoelectric layer 101 , a functional layer 102 , a high-sonic layer 103 and a support layer 104 unless otherwise stated below.

Please continue to refer to FIG. 2, the IDT may include an input bus bar 21, an output bus bar 22, a plurality of first interdigital electrodes 23 electrically connected to the input bus bar 21, and a plurality of first interdigital electrodes 23 electrically connected to the output bus bar 22. A second interdigitated electrode 24. Wherein, a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 are alternately arranged between the input bus bar 21 and the output bus bar 22, and the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes The electrodes 24 are insulated from each other.

As shown in FIG. 3 , taking a SAW filter including a resonator as an example, the input bus bar 21 is electrically connected to the input terminal Input of the SAW filter, and the output bus bar 22 is electrically connected to the output terminal Output of the SAW filter. The working principle of the SAW filter is as follows: an electrical signal is input to the input bus bar 21 through the input terminal Input, and the piezoelectric layer 101 in the piezoelectric substrate 10 converts electrical energy into mechanical energy according to the inverse piezoelectric effect. The piezoelectric layer 101 is deformed under the action of mechanical energy, and drives the deformation of the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 disposed on the piezoelectric layer 101, thereby forming on the surface of the piezoelectric layer 101 The surface acoustic wave transmitted along the first direction can also be said to form a longitudinal acoustic wave on the surface of the piezoelectric layer 101, and the resonance of the longitudinal acoustic wave is the main mode resonance. Further, according to the piezoelectric effect, charges are generated on the surface of the piezoelectric layer 101 , the acoustic signal is converted into an electrical signal, and the electrical signal is output from the output terminal Output through the output bus bar 22 . SAW filters can achieve filtering by confining longitudinal sound waves inside the resonator. Wherein, the first direction is a vertical direction from the first interdigital electrode 23 to the second interdigital electrode 24 , and the longitudinal direction is the same as the first direction.

In the above process, in order to ensure that the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 can deform along with the piezoelectric layer 101 to play the role of energy conversion, the plurality of first interdigital electrodes 23 can be The plurality of second interdigital electrodes 24 are in direct contact with the piezoelectric layer 101 . As for the input bus bar 21 and the output bus bar 22 , the input bus bar 21 and the output bus bar 22 may or may not be in direct contact with the piezoelectric layer 101 .

However, in addition to most of the surface acoustic waves propagating in the first direction, a small part of the surface acoustic waves propagates in the second direction. It can also be said that in addition to most of the longitudinal sound waves, there are also a small number of transverse sound waves, and the transverse sound waves resonate in a transverse mode (TM) other than the main mode resonance. As shown in Figure 4, transverse acoustic waves cause many unwanted spurious peaks on the admittance curve of the resonator. These spurious peaks lead to a reduction in the Q value of the resonator, which in turn affects the operating frequency and insertion loss of the SAW filter, and also affects the in-band ripple of the SAW filter, deteriorating the passband performance. Wherein, the second direction is a vertical direction from the input bus bar 21 to the output bus bar 22 , and the second direction is perpendicular to the first direction.

Based on this, the embodiment of the present application improves the structure of the resonator to reduce the transverse sound wave, thereby increasing the Q value of the resonator, thereby increasing the operating frequency of the SAW filter, reducing the insertion loss of the SAW filter, and improving the influence of the transverse sound wave on the SAW The problem of in-band ripple and passband performance of the filter.

As shown in FIG. 5 , the resonator of the present application includes an input confluence region, a transduction region and an output confluence region. The input bus bar 21 is located in the input bus area, the output bus bar 22 is located in the output bus area, and a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 are located in the transduction area. The piezoelectric layer 101 should be located at least in the confluence area so as to be in direct contact with the first interdigital electrode 23 and the second interdigital electrode 24 .

It should be noted here that, as shown in FIG. 6a, since the input bus bar 21 is electrically connected to the first interdigital electrode 23, when at least part of the input bus bar 21 is in direct contact with the piezoelectric layer 101, at least part of the The input bus bar 21 can also be used as the first interdigital electrode 23 , and this part of the input bus bar 21 can also play a role of energy conversion.

Similarly, as shown in FIG. 6a, since the output bus bar 22 is electrically connected to the second interdigital electrode 24, when at least part of the output bus bar 22 is in direct contact with the piezoelectric layer 101, at least part of the output bus bar 22 is in direct contact with the piezoelectric layer 101. 22 can also be used as the second interdigital electrode 24, and this part of the output bus bar 22 can also play the role of energy conversion.

It should be noted here that, FIG. 6 a and FIG. 6 b , as well as any side view of the resonator below, use the input bus bar 21 and a first interdigitated electrode 23 as examples to introduce the structure of the resonator. In addition, FIG. 6 a and FIG. 6 b , as well as the side view of any one of the resonators below, can also be a structural relationship diagram of the output bus bar 22 and the second interdigital electrode 24 . When Fig. 6a and Fig. 6b, and the side view of any one of the following resonators are used to introduce the structural relationship diagram of the output bus bar 22 and the second interdigitated electrode 24, the input bus bar in the figure can be used as the output bus bar, the first The interdigitated electrode can be used as the second interdigitated electrode, the input confluence area can be used as the output confluence area, and the output confluence area can be used as the output confluence area.

Please continue to refer to FIG. 6 a - FIG. 9 b , on the upper surface of the piezoelectric substrate 10 , the part located in the transducing area is not in the same plane as the part located in the input confluence area and the output confluence area.

In the embodiment of the present application, the input bus bar 21 , the output bus bar 22 , a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 may be formed using a semiconductor process. Since a plurality of first interdigital electrodes 23 are electrically connected to the input bus bar 21, on the upper surface of the piezoelectric substrate 10, the part located in the transduction area and the part located in the input bus area are not in the same plane, that is, the first surface The part from the input confluence area to the transduction area has steps. Therefore, along the second direction, there is a discontinuity between the plurality of first interdigital electrodes 23 and the input bus bar 21 , thereby resulting in discontinuity of the transverse sound wave propagating along the second direction. By making the transverse sound wave discontinuously propagate in the second direction, the propagation speed of the transverse sound wave along the second direction can be reduced, thereby effectively suppressing the transverse sound wave, improving the Q value of the resonator, and then increasing the operating frequency of the SAW filter and reducing the SAW filter The insertion loss of the filter, and at the same time improve the problem that the transverse sound wave affects the in-band ripple and passband performance of the SAW filter.

Similarly, as shown in FIG. 6a, since a plurality of second interdigital electrodes 24 are electrically connected to the output bus bar 22, on the upper surface of the piezoelectric substrate 10, the part located in the transduction area and the part located in the output bus area are not in the same direction. The same plane, that is, the part of the first surface from the output confluence area to the transducing area has a step. Therefore, along the second direction, there is a discontinuity between the plurality of second interdigital electrodes 24 and the output bus bar 22 , thereby resulting in discontinuity of the transverse sound wave propagating along the second direction. By making the transverse sound wave discontinuously propagate in the second direction, the propagation speed of the transverse sound wave along the second direction can be reduced, thereby effectively suppressing the transverse sound wave, improving the Q value of the resonator, and then increasing the operating frequency of the SAW filter and reducing the SAW filter The insertion loss of the filter, and at the same time improve the problem that the transverse sound wave affects the in-band ripple and passband performance of the SAW filter.

Moreover, compared with the solution of forming the first interdigital electrode 23 and the second interdigital electrode 24 with uniform thickness, the electrode layer is then formed above the first interdigital electrode 23 and the second interdigital electrode 24 with uniform thickness. The embodiment of the present application can take advantage of the fact that the part of the upper surface of the piezoelectric substrate 10 located in the transducing region is not on the same plane as the part located in the input confluence region and the output confluence region, and form a discontinuous first through the same semiconductor process. The interdigitated electrodes 23 and the input bus bar 21, as well as the discontinuous second interdigitated electrodes 24 and the output bus bar 22, can reduce at least one semiconductor process, simplify the manufacturing process of the resonator, and can also save the mask for preparing the electrode layer. template (mask), thereby saving the cost of preparing the resonator. It should be noted here that when the same semiconductor process is used to form the input bus bar 21, the output bus bar 22, a plurality of first interdigital electrodes 23, and a plurality of second interdigital electrodes 24, the input bus bar 21, the output bus bar The materials of the bus bar 22 , the plurality of first interdigital electrodes 23 , and the plurality of second interdigital electrodes 24 are all the same.

In some possible implementations, the input bus bar 21, the output bus bar 22, a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 of the interdigital transducer can be formed in one semiconductor process to simplify The manufacturing process of the interdigital transducer saves the mask used to form the interdigital transducer, thereby saving the cost of preparing the resonator. Of course, it is also possible to use multiple semiconductor processes to distribute and form the input bus bar 21, output bus bar 22, multiple first interdigital electrodes 23 and multiple second interdigital electrodes 24 of the IDT. There is no limit to this. In addition, the embodiment of the present application does not limit the realization of the upper surface of the piezoelectric substrate 10 , where the part located in the transducing region is not on the same plane as the part located in the input confluence region and the output confluence region. Optionally, it can be realized by making the thickness of the part of the piezoelectric substrate 10 located in the transducing region different from the thickness of the part of the piezoelectric substrate 10 located in the input confluence region and the output confluence region. For example, as shown in FIGS. 6a-7b, the thickness of the portion of the piezoelectric substrate 10 located in the transducing area is greater than the thickness of the portion located in the input confluence area and the output confluence area. Alternatively, as shown in FIGS. 8a-9b, the thickness of the portion of the piezoelectric substrate 10 located in the transducing area is smaller than the thickness of the portion located in the input confluence area and the output confluence area.

For example, as shown in FIG. 6a and FIG. 6b, taking the thickness of the portion of the piezoelectric substrate 10 located in the transducing area is respectively greater than the portion located in the input confluence area and the output confluence area, as shown in FIG. 6a and FIG. 6b, The piezoelectric substrate 10 includes a first piezoelectric substrate 11, the first piezoelectric substrate 11 is provided with a first groove at the part of the input bus area, and the input bus bar 21 is arranged in the first groove; the first piezoelectric substrate 11 The part located in the output bus area is provided with a second groove, and the output bus bar 22 is arranged in the second groove; a plurality of first interdigitated electrodes 23 and a plurality of second interdigitated electrodes 24 are arranged in the first groove and the second interdigitated electrode 24. between the second grooves. In this way, on the upper surface of the piezoelectric substrate 10 , the part located in the transducing region and the part located in the input confluence region and the output confluence region are not in the same plane.

In this example, since the input bus bar 21 and the output bus bar 22 do not have high requirements on the piezoelectric layer 101, the bottom surfaces of the first groove and the second groove can be made of the piezoelectric layer 101, the functional layer 102, the high sound velocity The surface of any one of the layer 103 and the support layer 104. Further, since the surface of the piezoelectric substrate 10 without grooves is flatter than the surface of the piezoelectric substrate with grooves. Therefore, in this example, by opening the first groove in the input confluence area and the second groove in the output confluence area, it can avoid the piezoelectric layer 101 being located in the transduction area due to the process of opening the first groove and the second groove. The surface of the portion is not flat enough, thereby affecting the transduction effect of the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 . Moreover, compared with the following example in which the piezoelectric substrate 10 includes the first piezoelectric substrate 11 and the second piezoelectric substrate 12, this example can not only save the process of depositing the second piezoelectric substrate 12, but also reduce the overall size of the resonator. thickness.

In some possible implementation manners, the embodiment of the present application does not limit the depth of the first groove, the depth of the second groove, the thickness of the input bus bar 21 and the thickness of the output bus bar 22 . Alternatively, as shown in FIG. 6 a , along the thickness direction of the piezoelectric substrate 10 , the thickness of the input bus bar 21 may be greater than the depth of the first groove, and the thickness of the output bus bar 22 may be greater than the depth of the second groove. Alternatively, as shown in FIG. 6 b , along the thickness direction of the piezoelectric substrate 10 , the thickness of the input bus bar 21 may be smaller than the depth of the first groove, and the thickness of the output bus bar 22 may be smaller than the depth of the second groove. Of course, along the thickness direction of the piezoelectric substrate 10, the thickness of the input bus bar 21 can also be equal to the depth of the first groove, and the thickness of the output bus bar 22 can also be equal to the depth of the second groove, as long as the thickness of the first groove The presence of the plurality of first interdigital electrodes 23 is discontinuous with the input bus bar 21 ; due to the existence of the second groove, the plurality of second interdigital electrodes 24 are discontinuous with the output bus bar 22 .

When the thicknesses of the input bus bar 21, the output bus bar 22, a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 are constant, the depths of the first groove and the second groove are different. The continuity difference between the electrode 23 and the input bus bar 21 is different, the continuity difference between the second interdigitated electrode 24 and the output bus bar 22 is different, and the intensity of the transverse sound wave that can be suppressed is different. Exemplarily, the depth range of the first groove and the second groove may be 0.001λ˜1λ. Among them, λ represents the wavelength of the longitudinal sound wave. Figure 10a shows the admittance diagrams of the resonators corresponding to the first grooves and the second grooves of different depths, and Figure 10b shows the conductance diagrams of the resonators corresponding to the first grooves and the second grooves of different depths , the smoother the curves in the admittance diagram and conductance diagram, the greater the intensity of the suppressed transverse sound wave. Optionally, according to Figure 10a and Figure 10b, it can be concluded that when the depth of the first groove and the second groove is 0.05λ, the curves in the admittance diagram and the conductance diagram are the smoothest, and the intensity of the suppressed transverse sound wave is greater , the Q value of the resonator is the largest, the operating frequency of the SAW filter is the largest, and the insertion loss is the smallest, which can improve the in-band ripple and passband performance of the SAW filter affected by the transverse sound wave to the greatest extent.

For another example, as shown in FIG. 7a and FIG. 7b, still taking the thickness of the part of the piezoelectric substrate 10 located in the transducing area as an example, which is respectively greater than the part located in the input confluence area and the output confluence area, the piezoelectric substrate 10 includes a first A piezoelectric substrate 11 and a second piezoelectric substrate 12 disposed between the first piezoelectric substrate 11 and the IDT. The first piezoelectric substrate 11 is at least located in the input confluence area, the transduction area and the output confluence area, and the second piezoelectric substrate 12 is located in the transduction area. A plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 are arranged on the side of the second piezoelectric substrate 12 away from the first piezoelectric substrate 11, and the input bus bar 21 and the output bus bar 22 are arranged on the first piezoelectric substrate 12. on base 11. In this way, on the upper surface of the piezoelectric substrate 10 , the part located in the transducing region and the part located in the input confluence region and the output confluence region are not in the same plane.

In this example, by forming the second piezoelectric substrate 12 between the first piezoelectric substrate 11 and the interdigital transducers, the flatness of the portion of the piezoelectric substrate 10 located in the transducing region can be ensured, thereby ensuring that multiple first piezoelectric substrates Transduction effect of one interdigital electrode 23 and multiple second interdigital electrodes 24 .

In some possible implementations, in the case where the multiple first interdigital electrodes 23 and the multiple second interdigital electrodes 24 are only located in the transduction area, the first piezoelectric substrate 11 may be the functional layer 102, the high-acoustic velocity layer 103 Any one of the support layer 104 and the first piezoelectric layer of the piezoelectric layer 101 , the second piezoelectric substrate 12 may be the second piezoelectric layer of the piezoelectric layer 101 . In the case where a plurality of first interdigitated electrodes 23 are also located in the input confluence area (or an input confluence area and an output confluence area), and a plurality of second interdigital electrodes 24 are also located in an output confluence area (or an output confluence area and an input confluence area) Next, the first piezoelectric substrate 11 may be the first piezoelectric layer of the piezoelectric layer 101 , and the second piezoelectric substrate 12 may be the second piezoelectric layer of the piezoelectric layer 101 .

In some possible implementation manners, the embodiment of the present application does not limit the thickness of the second piezoelectric substrate 12 , the thickness of the input bus bar 21 and the thickness of the output bus bar 22 . As shown in FIG. 7 a , along the thickness direction of the piezoelectric substrate 10 , the thickness of the input bus bar 21 and the thickness of the output bus bar 22 may be greater than the thickness of the second piezoelectric substrate 12 . Alternatively, as shown in FIG. 7 b , along the thickness direction of the piezoelectric substrate 10 , the thickness of the input bus bar 21 and the thickness of the output bus bar 22 may be smaller than the thickness of the second piezoelectric substrate 12 . Of course, along the thickness direction of the piezoelectric substrate 10, the thickness of the input bus bar 21 and the thickness of the output bus bar 22 can also be equal to the thickness of the second piezoelectric substrate 12, as long as the plurality of first interdigital electrodes 23 and the input bus bar 21 It is not continuous, it only needs to be discontinuous between the plurality of second interdigital electrodes 24 and the output bus bar 22 .

For another example, as shown in FIG. 8a and FIG. 8b, taking the thickness of the part of the piezoelectric substrate 10 located in the transducing area as an example, the thickness of the part located in the input confluence area and the output confluence area is respectively smaller than that of the piezoelectric substrate 10. A piezoelectric substrate 11, the part of the first piezoelectric substrate 11 located in the transducing area is provided with a third groove. A plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 are located in the third groove, and the input bus bar 21 and the output bus bar 22 are respectively arranged on opposite sides of the third groove. In this way, on the upper surface of the piezoelectric substrate 10 , the part located in the transducing region and the part located in the input confluence region and the output confluence region are not in the same plane.

In some possible implementations, since the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 need to be in direct contact with the piezoelectric layer 101, the bottom surface of the third groove can be the bottom surface of the piezoelectric layer 101. On the surface, it can also be said that the first piezoelectric substrate 11 is a piezoelectric layer 101 .

In some possible implementation manners, the embodiment of the present application does not limit the depth of the third groove, the thickness of the plurality of first interdigital electrodes 23 and the thickness of the plurality of second interdigital electrodes 24 . Alternatively, as shown in FIG. 8 a , along the thickness direction of the piezoelectric substrate 10 , the thickness of the plurality of first interdigital electrodes 23 and the thickness of the plurality of second interdigital electrodes 24 may be greater than the depth of the third groove. Alternatively, as shown in FIG. 8 b , along the thickness direction of the piezoelectric substrate 10 , the thickness of the plurality of first interdigital electrodes 23 and the thickness of the plurality of second interdigital electrodes 24 may be smaller than the depth of the third groove. Of course, along the thickness direction of the piezoelectric substrate 10, along the thickness direction of the piezoelectric substrate 10, the thickness of the plurality of first interdigital electrodes 23 and the thickness of the plurality of second interdigital electrodes 24 can also be equal to the depth of the third groove , as long as the plurality of first interdigital electrodes 23 are discontinuous with the input bus bar 21 and the plurality of second interdigital electrodes 24 are discontinuous with the output bus bar 22 .

For another example, as shown in FIG. 9a and FIG. 9b, still taking the thickness of the part of the piezoelectric substrate 10 located in the transducing area as an example, which is respectively smaller than the thickness of the part located in the input confluence area and the output confluence area, the piezoelectric substrate 10 includes The first piezoelectric substrate 11 and the second piezoelectric substrate 12 are disposed between the first piezoelectric substrate 11 and the IDT. The first piezoelectric substrate 11 is located at least in the input confluence area, the transduction area and the output confluence area, and the second piezoelectric substrate 12 is located in the input confluence area and the output confluence area. A plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 are arranged on the first piezoelectric substrate 11, and the input bus bar 21 and the output bus bar 22 are arranged on the second piezoelectric substrate 12 away from the first piezoelectric substrate. 11 side. In this way, on the upper surface of the piezoelectric substrate 10 , the part located in the transducing region and the part located in the input confluence region and the output confluence region are not in the same plane.

In this example, by disposing a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 on the first piezoelectric substrate 11, the flatness of the portion of the piezoelectric substrate 10 located in the transducing region can be ensured, Thus, the transduction effect of the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 is ensured.

In some possible implementation manners, in the case where the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 are only located in the transducing region, the first piezoelectric substrate 11 may be the first part of the piezoelectric layer 101 The piezoelectric layer, the second piezoelectric substrate 12 may be any one of the second piezoelectric layer of the functional layer 102 , the high-sonic layer 103 , the supporting layer 104 and the piezoelectric layer 101 . In the case where a plurality of first interdigitated electrodes 23 are also located in the input confluence area (or an input confluence area and an output confluence area), and a plurality of second interdigital electrodes 24 are also located in an output confluence area (or an output confluence area and an input confluence area) Next, the first piezoelectric substrate 11 may be the first piezoelectric layer of the piezoelectric layer 101 , and the second piezoelectric substrate 12 may be the second piezoelectric layer of the piezoelectric layer 101 .

In some possible implementation manners, the embodiment of the present application does not limit the thickness of the second piezoelectric substrate 12 , the thickness of the plurality of first interdigital electrodes 23 and the thickness of the plurality of second interdigital electrodes 24 . As shown in FIG. 9 a , along the thickness direction of the piezoelectric substrate 10 , the thicknesses of the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 may be greater than the thickness of the second piezoelectric substrate 12 . Alternatively, as shown in FIG. 9 b , along the thickness direction of the piezoelectric substrate 10 , the thicknesses of the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 may be smaller than the thickness of the second piezoelectric substrate 12 . Of course, along the thickness direction of the piezoelectric substrate 10, the thicknesses of the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 can also be equal to the thickness of the second piezoelectric substrate 12, as long as the plurality of first fork electrodes The finger electrodes 23 are discontinuous with the input bus bar 21 , and the plurality of second interdigital electrodes 24 are discontinuous with the output bus bar 22 .

For any of the above examples, the thickness of the portion of the piezoelectric substrate 10 located at the input confluence area may be the same as the thickness of the portion located at the output confluence area. In this way, on the one hand, the consistency of the structure of the first interdigital electrode 23 and the second interdigital electrode 24 can be ensured, so that the transverse sound wave can pass through the discontinuous part of the first interdigital electrode 23 and the input bus bar 21, and The discontinuous part of the second interdigitated electrode 24 and the output bus bar 22 enters the piston (piston) working mode at the same time. The step of the transducing area enters the piston working mode at the same time, thereby better suppressing the transverse sound wave; on the other hand, in the case that the first piezoelectric substrate 11 includes the first groove and the second groove, the same light can be used The first groove and the second groove are obtained by simultaneous etching, which simplifies the manufacturing process of the piezoelectric substrate 10 .

In addition, in order to ensure mutual insulation between the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24, avoid short circuiting between the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 through the output bus bar 22 , to prevent the plurality of second interdigital electrodes 24 from short-circuiting with the plurality of first interdigital electrodes 23 through the input bus bar 21 . In some embodiments, as shown in FIGS. 5-9 b , 11 and 12 , the edge of the input confluence region facing the output confluence region has a first distance from the edge of the input bus bar 21 toward the output bus bar 22 . Since the plurality of first interdigital electrodes 23 are electrically connected to the input bus bar 21 , the plurality of first interdigital electrodes 23 are also located at the first pitch. The edge of the output bus area facing the input bus area has a second distance from the edge of the output bus bar 22 facing the input bus bar 21 . Since the plurality of second interdigital electrodes 24 are electrically connected to the output bus bar 22 , the plurality of second interdigital electrodes 24 are also located at the second pitch. In some other embodiments, as shown in FIG. 13-FIG. 17b, the plurality of first interdigitated electrodes 23 are spaced from the edge of the output bus bar 22 toward the output bus bar 22; the plurality of second fork electrodes The edge of the finger electrode 24 facing the input bus bar 21 has a distance from the edge of the input bus region facing the output bus region.

Optionally, when the input bus area and the input bus bar 21 have a first distance, and the output bus area and the output bus bar 22 have a second distance, as shown in FIGS. 23 towards the edge of the output bus bar 22, flush with the edge of the output confluence area towards the input confluence area; a plurality of second interdigital electrodes 24 towards the edge of the input bus bar 21, and the edge of the input confluence area towards the output confluence area flush. Compared with the edge of the plurality of first interdigital electrodes 23 facing the output bus bar 22 and the edge of the output bus area facing the input bus area, the plurality of second interdigital electrodes 24 faces the edge of the input bus bar 21 and the input bus area. In the scheme of having a spacing towards the edge of the output confluence area, the embodiment of the present application can make a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 continuously arranged in the transduction area along the second direction, thereby avoiding surface acoustic waves Extra reflections at edges.

Optionally, when there is a first distance between the input confluence area and the input bus bar 21, and a second distance between the output confluence area and the output bus bar 22, as shown in Fig. 11 and Fig. 12, after ensuring a plurality of first forks In the case where the finger electrode 23 and the plurality of second interdigital electrodes 24 are insulated from each other, the plurality of first interdigital electrodes 23 can also extend from the input confluence area to the output confluence area, and the plurality of second interdigital electrodes 24 can also Extends from the output confluence area to the input confluence area, thereby increasing the design freedom of the resonator.

In some possible implementation manners, for any of the above-mentioned resonators, along the second direction, the first interdigital electrode 23 faces the edge of the output bus bar 22, and reaches the second second interdigital electrode 23 adjacent to the first interdigital electrode 23. The distance between the edges of the two interdigitated electrodes facing the input bus bar 21 may range from 10λ˜40λ. It can also be said that for any of the above resonators, the aperture size may range from 10λ to 40λ. Within the aperture size range, the interdigital transducer of the present application may also have other structures, which are not limited in this embodiment of the present application.

In some possible implementation manners, the embodiment of the present application does not limit the size of the first pitch and the second pitch, as long as the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 are insulated from each other. Optionally, the size range of the first distance and the second distance may be 0.1λ˜5λ. For example, the size ranges of the first pitch and the second pitch may be 0.1λ, λ, 2.5λ, 5λ, and so on. Also, the size of the first pitch and the second pitch may be the same.

In some possible implementations, when the multiple first interdigital electrodes 23 are still located at the first interval and the multiple second interdigital electrodes 24 are also located at the second interval, the piezoelectric substrate 10 is located at the first The portion at the pitch and the second pitch may be the piezoelectric layer 101 . In the case where the plurality of first interdigital electrodes 23 also extend from the input confluence region to the output confluence region, and the plurality of second interdigital electrodes 24 also extend from the output confluence region to the input confluence region, the piezoelectric substrate 10 is located at the output confluence region. The overlapping portion of the plurality of first interdigital electrodes 23 in the confluence region and the overlapping portion of the plurality of second interdigital electrodes 24 located in the input confluence region may be the piezoelectric layer 101 .

In some possible implementations, there is a distance between the edge of the first interdigital electrodes 23 facing the output bus bar 22 and the edge of the output bus region facing the input bus region, and the plurality of second interdigital electrodes 24 facing the input bus bar 21 When there is a distance between the edge of the input confluence area and the edge of the input confluence area towards the output confluence area, as shown in Fig. Flat; the edge of the output confluence region facing the input confluence region is flush with the edge of the output bus bar 22 facing the input bus bar 21 . Or, the edge of the input confluence area towards the output confluence area has a first distance from the edge of the input bus bar 21 towards the output bus bar 22; The edges have a second spacing.

In addition, as shown in FIG. 18 , on the basis of any of the above-mentioned embodiments, along the first direction, the width of the part of the first interdigital electrode 23 located at the step between the transducing region and the input confluence region can also be greater than that of the first interdigital electrode 23 . The width of other parts of the first interdigital electrode 23 ; the width of the second interdigital electrode 24 at the step between the transducing region and the output confluence region can also be greater than the width of other parts of the second interdigital electrode 24 . Since the width of the first interdigital electrode 23 and the second interdigital electrode 24 is larger at the step, there is discontinuity in the first interdigital electrode 23 and the second interdigital electrode 24 along the second direction, resulting in A propagating transverse sound wave is discontinuous as it propagates. By making the transverse sound wave propagate discontinuously in the second direction, the propagation speed of the transverse sound wave along the second direction can be reduced, so that the transverse sound wave can be effectively suppressed, the Q value of the resonator can be improved, the operating frequency of the SAW filter can be increased, and the SAW filter can be reduced. The insertion loss of the filter, and at the same time improve the problem that the transverse sound wave affects the in-band ripple and passband performance of the SAW filter.

As shown in Figure 19, the embodiment of the present application also provides a method for manufacturing a resonator, including:

S191 , forming the piezoelectric substrate 10 .

Specifically, the piezoelectric substrate 10 can be formed in the following four ways.

The first way:

As shown in FIG. 20a, the stacked first piezoelectric film 111 and the first photoresist 31 are sequentially formed.

In some possible ways, chemical vapor deposition (chemical vapor deposition, CVD), or physical vapor deposition (physical vapor deposition, PVD), or atomic layer deposition (atomic layer deposition, ALD) can be used to deposit the first pressure. Electric film 111. The first photoresist 31 can be coated on the first piezoelectric film 111 by using a spin coating process.

As shown in FIG. 20 b , the first photoresist 31 is exposed and developed to obtain a first photoresist pattern 311 , and the first photoresist pattern 311 exposes the input confluence region and the output confluence region.

As shown in FIG. 20c, under the protection of the first photoresist pattern 311, the first piezoelectric film 111 is etched to obtain the first piezoelectric substrate 11. The first piezoelectric substrate 11 includes a first groove and a first piezoelectric substrate. Two grooves.

Afterwards, as shown in FIG. 20c, the first photoresist pattern 311 may also be stripped. For example, the first photoresist pattern 311 may be stripped by means of mechanical stripping or laser stripping.

The second way:

As shown in FIG. 21 a , a first piezoelectric film 111 , a second piezoelectric film 121 and a second photoresist 32 are formed in sequence.

In some possible implementation manners, the first piezoelectric film 111 and the second piezoelectric film 121 may be deposited by CVD, PVD, or ALD processes. The second photoresist 32 may be coated on the side of the second piezoelectric film 121 facing away from the first piezoelectric film 111 by using a spin coating process.

In some possible implementations, since the first piezoelectric film 111 and the first piezoelectric substrate 11 are located in the input confluence area, the energy conversion area and the output confluence area, the first piezoelectric film 111 can be used as the first piezoelectric base 11.

As shown in FIG. 21b, the second photoresist 32 is exposed, and the second photoresist pattern 321 is obtained after development. The second photoresist pattern 321 exposes the input confluence region and the output confluence region, or the second photoresist The pattern 321 exposes an area other than the transducing area.

As shown in FIG. 21c, under the protection of the second photoresist pattern 321, the second piezoelectric film 121 is etched to obtain the second piezoelectric substrate 12, and the second piezoelectric substrate 12 is located in the transducing region.

Afterwards, as shown in FIG. 21c, the second photoresist pattern 321 may also be stripped. For example, the second photoresist pattern 321 may be stripped by mechanical stripping or laser stripping.

The third way:

As shown in FIG. 22a, the laminated first piezoelectric film 111 and the third photoresist 33 are sequentially formed. In some possible implementation manners, the first piezoelectric film 111 may be deposited by CVD, PVD, or ALD processes. The third photoresist 33 can be coated on the first piezoelectric film 111 by using a spin coating process.

As shown in FIG. 22b, the third photoresist 33 is exposed and developed to obtain a third photoresist pattern 331, and the third photoresist pattern 331 exposes the transducing region.

As shown in FIG. 22c, under the protection of the third photoresist pattern 331, the first piezoelectric film 111 is etched to obtain the first piezoelectric substrate 11, and the first piezoelectric substrate 11 includes a third groove.

Afterwards, as shown in FIG. 22c, the third photoresist pattern 331 may also be stripped. For example, the third photoresist pattern 331 may be stripped by means of mechanical stripping or laser stripping.

The fourth way:

As shown in FIG. 23 a , the first piezoelectric film 111 , the second piezoelectric film 121 and the fourth photoresist 34 are formed sequentially.

In some possible implementation manners, the first piezoelectric film 111 and the second piezoelectric film 121 may be deposited by CVD, PVD, or ALD processes. The fourth photoresist 34 may be coated on the side of the second piezoelectric film 121 facing away from the first piezoelectric film 111 by using a spin coating process.

As shown in Figure 23b, the fourth photoresist 34 is exposed and developed to obtain a fourth photoresist pattern 341, the fourth photoresist pattern 341 exposes the transduction region, or the fourth photoresist pattern 341 exposes the The input catchment area and the area outside the output catchment area.

As shown in FIG. 23c, under the protection of the fourth photoresist pattern 341, the second piezoelectric film 121 is etched to obtain the second piezoelectric substrate 12, and the second piezoelectric substrate 12 is located in the input confluence region and the output confluence region. district.

Afterwards, as shown in Figure 23c, the input confluence area and the output confluence area can also be peeled off. For example, the input confluence region and the output confluence region can be peeled off by means of mechanical peeling or laser peeling.

Of course, in addition to the above four methods, other methods can also be used to form the piezoelectric substrate 10, so that on the upper surface of the piezoelectric substrate 10, the part located in the transducing region is not the same as the part located in the input confluence region and the output confluence region. plane, which is not limited in this embodiment of the present application.

S192, forming an interdigital transducer on the piezoelectric substrate 10; the interdigital transducer includes an input bus bar 21, an output bus bar 22, a plurality of first interdigital electrodes 23 electrically connected to the input bus bar 21, and A plurality of second interdigital electrodes 24 to which the output bus bars 22 are electrically connected. The input bus bar 21 is located in the input bus area, the output bus bar 22 is located in the output bus area, and a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 are located in the transduction area. Wherein, on the upper surface of the piezoelectric substrate 10 , the part located in the transducing region is not on the same plane as the part located in the input confluence region and the output confluence region.

Specifically, as shown in FIG. 24, forming an interdigital transducer on a piezoelectric substrate 10 may include the following steps:

S1921, as shown in FIG. 25 a , forming a fifth photoresist 35 on the piezoelectric substrate 10 .

In some possible implementation manners, the fifth photoresist 35 can be coated on the piezoelectric substrate 10 by using a spin-coating process.

S1922, as shown in FIG. 25b, exposing the fifth photoresist 35 to obtain a fifth photoresist pattern 351 after development, and the fifth photoresist pattern 351 exposes the area where the IDT to be formed is located.

It should be noted here that, according to different requirements, the area where the IDT is located can be the area where the IDT provided by any of the above-mentioned embodiments, so that the fifth light covering different areas can be determined. For the resist pattern 351 , FIG. 25 b only illustrates an example in which the piezoelectric substrate 10 includes the first piezoelectric substrate 11 , and the first piezoelectric substrate 11 includes the first groove and the second groove.

S1923, as shown in FIG. 25c , forming an electrode film 20 on the side of the fifth photoresist pattern 351 away from the piezoelectric substrate 10 .

In some possible implementation manners, the material of the electrode film 20 may include any one of aluminum, gold, silver, copper, molybdenum, and tungsten. The electrode film 20 may be formed on the side of the fifth photoresist pattern 351 away from the piezoelectric substrate 10 by sputtering.

S1924, as shown in FIG. 25d , strip the fifth photoresist pattern 351 to obtain an IDT from the electrode film 20 .

Here, in the area where the fifth photoresist pattern 351 is located, the electrode film 20 is formed on the side of the fifth photoresist pattern 351 away from the piezoelectric substrate 10, so when the fifth photoresist pattern 351 is peeled off, the electrodes The part of the film 20 on the side of the fifth photoresist pattern 351 facing away from the piezoelectric substrate 10 is also peeled off accordingly. And because the fifth photoresist pattern 351 exposes the area where the IDT to be formed is located, therefore, the electrode film 20 is in direct contact with the piezoelectric substrate 10 in the area where the IDT to be formed is located. That is, the electrode film 20 is directly fixed on the piezoelectric substrate 10, and this part of the electrode film 20 is an interdigital transducer. The IDT includes an input bus bar 21 , an output bus bar 22 , a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 .

Using the above steps S1921-S1924, the input bus bar 21, output bus bar 22, multiple first interdigital electrodes 23 and multiple second interdigital electrodes 24 of the same material can be formed by only one semiconductor process, simplifying the preparation of the resonator The process steps save mask and reduce the preparation cost.

Of course, the input bus bar 21, the output bus bar 22, a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24 of the interdigital transducer can also be formed on the foregoing piezoelectric substrate 10 in other ways. The embodiment of the application does not limit this.

It should be noted that, when actually preparing the resonator of the present application, it is also possible to purchase the prepared piezoelectric substrate 10 in advance, and directly form the interdigital transducer on the prepared piezoelectric substrate 10 . That is, the manufacturing method of the resonator of the present application only executes step S192.

In addition, other explanations and beneficial effects of the manufacturing method of the resonator are the same as those of the resonator in the foregoing embodiments, and will not be repeated here.

The embodiments of the present application have been described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementations. The above-mentioned specific implementations are only illustrative and not restrictive. Those of ordinary skill in the art will Under the inspiration of this application, without departing from the purpose of this application and the scope of protection of the claims, many forms can also be made, all of which belong to the protection of this application.

Claims

A resonator, characterized in that it includes a piezoelectric substrate and an interdigital transducer disposed on the upper surface of the piezoelectric substrate;

The resonator includes an input confluence area, a transduction area, and an output confluence area; the interdigital transducer includes an input bus bar, an output bus bar, a plurality of first interdigital electrodes electrically connected to the input bus bar, and a plurality of second interdigitated electrodes electrically connected to the output bus bar; the input bus bar is located in the input bus area, the output bus bar is located in the output bus area, and the plurality of first interdigitated electrodes and The plurality of second interdigital electrodes are located in the transduction area;

Wherein, on the upper surface of the piezoelectric substrate, the part located in the transducing region is not in the same plane as the part located in the input confluence region and the output confluence region.
The resonator according to claim 1, wherein the thickness of the part of the piezoelectric substrate located in the transducing region is greater than the thickness of the parts located in the input confluence region and the output confluence region.
The resonator of claim 2, wherein the piezoelectric substrate comprises a first piezoelectric substrate;

The part of the first piezoelectric substrate located in the input confluence area is provided with a first groove, and the part of the first piezoelectric substrate located in the output confluence area is provided with a second groove.
The resonator according to claim 3, wherein the depths of the first groove and the second groove range from 0.001λ to 1λ;

Wherein, λ represents the wavelength of the longitudinal sound wave generated by the resonator, and the longitudinal sound wave propagates along the vertical direction from the first interdigital electrode to the second interdigital electrode.
The resonator according to claim 2, wherein the piezoelectric substrate comprises a first piezoelectric substrate and a second piezoelectric substrate disposed between the first piezoelectric substrate and the IDT. base;

The first piezoelectric substrate is located at least in the input confluence region, the transduction region and the output confluence region; the second piezoelectric substrate is located in the transduction region.
The resonator according to claim 1, wherein the thickness of the portion of the piezoelectric substrate located in the transducing area is smaller than the thickness of the portion located in the input confluence area and the output confluence area.
The resonator of claim 6, wherein the piezoelectric substrate comprises a first piezoelectric substrate;

The part of the first piezoelectric substrate located in the transducing area is provided with a third groove.
The resonator according to claim 6, wherein the piezoelectric substrate comprises a first piezoelectric substrate and a second piezoelectric substrate disposed between the first piezoelectric substrate and the IDT. base;

The first piezoelectric substrate is located at least in the input confluence area, the transduction area and the output confluence area; the second piezoelectric substrate is located in the input confluence area and the output confluence area.
The resonator according to any one of claims 1-8, wherein the thickness of the piezoelectric substrate at the input confluence region is the same as the thickness of the piezoelectric substrate at the output confluence region .
The resonator according to any one of claims 1-9, wherein the edge of the input confluence region facing the output confluence region has a first spacing;

An edge of the output bus area facing the input bus area has a second distance from an edge of the output bus bar facing the input bus bar.
The resonator according to claim 10, wherein the edge of the plurality of first interdigitated electrodes facing the output bus bar is flush with the edge of the output bus area facing the input bus bar;

Edges of the plurality of second interdigitated electrodes facing the input bus bar are flush with edges of the input bus region facing the output bus region.
The resonator of claim 10, wherein the plurality of first interdigitated electrodes extend from the input confluence region to the output confluence region;

The plurality of second interdigitated electrodes extend from the output junction area to the input junction area.
The resonator according to any one of claims 10-12, characterized in that, the size range of the first distance and the second distance is 10%λ˜5λ;

Wherein, λ represents the wavelength of the longitudinal sound wave generated by the resonator, and the longitudinal sound wave propagates along the vertical direction from the first interdigital electrode to the second interdigital electrode.
The resonator according to any one of claims 1-9, wherein the plurality of first interdigitated electrodes face toward the edge of the output bus bar, and the edges of the output bus bar toward the input bus bar The edges have spacing;

The edge of the plurality of second interdigitated electrodes facing the input bus bar has a distance from the edge of the input bus region facing the output bus region.
A filter, characterized by comprising one or more resonators according to any one of claims 1-14.
A method for preparing a resonator, characterized in that the resonator is divided into an input bus bar area, a transduction area, and an output bus bar area; the method includes:

forming a piezoelectric substrate;

An interdigital transducer is formed on the upper surface of the piezoelectric substrate; the interdigital transducer includes an input bus bar, an output bus bar, a plurality of first interdigital electrodes electrically connected to the input bus bar, and A plurality of second interdigitated electrodes electrically connected to the output bus bar; the input bus bar is located in the input bus area, the output bus bar is located in the output bus area, the plurality of first interdigitated electrodes and the The plurality of second interdigital electrodes are located in the transduction area;

Wherein, on the upper surface of the piezoelectric substrate, the part located in the transducing region is not in the same plane as the part located in the input confluence region and the output confluence region.
The method for preparing a resonator according to claim 16, wherein said forming the piezoelectric substrate comprises:

forming a first piezoelectric film;

Using a photolithography process, the part of the first piezoelectric film located at the input confluence region and the output confluence region is etched to form a first piezoelectric substrate; the first piezoelectric substrate includes A first groove in the input confluence area and a second groove in the output confluence area.
The method for preparing a resonator according to claim 16, wherein said forming the piezoelectric substrate comprises:

sequentially forming a stacked first piezoelectric substrate and a second piezoelectric film, the first piezoelectric substrate is at least located in the input confluence region, the transduction region and the output confluence region;

Using a photolithography process, the part of the second piezoelectric film located at the input confluence area and the output confluence area is etched to form a second piezoelectric substrate; the second piezoelectric substrate is located at the transducer Energy zone.
The method for preparing a resonator according to claim 16, wherein said forming the piezoelectric substrate comprises:

forming a first piezoelectric film;

A photolithography process is used to etch the part of the first piezoelectric film located in the transducing region to form a first piezoelectric substrate; the first piezoelectric substrate includes a third piezoelectric substrate located in the transducing region groove.
The method for preparing a resonator according to claim 16, wherein said forming the piezoelectric substrate comprises:

sequentially forming a stacked first substrate and a second piezoelectric film, the first piezoelectric substrate is at least located in the input confluence region, the transduction region and the output confluence region;

Using a photolithography process, the part of the second piezoelectric film located in the transducing region is etched to form a second piezoelectric substrate; the second piezoelectric substrate is located in the input confluence region and the output confluence area.
The method for preparing a resonator according to any one of claims 16-20, wherein said forming an interdigital transducer on said piezoelectric substrate comprises:

forming a photoresist on the piezoelectric substrate, exposing the photoresist, and obtaining a photoresist pattern after development; the photoresist pattern exposes the area where the interdigital transducer to be formed is located;

forming an electrode film on the side of the photoresist pattern away from the piezoelectric substrate;

The photoresist pattern is stripped off, and the interdigital transducer is obtained from the electrode film.