WO2022087825A1

WO2022087825A1 - Resonator and manufacturing method therefor, filter, and electronic device

Info

Publication number: WO2022087825A1
Application number: PCT/CN2020/123997
Authority: WO
Inventors: 鲍景富; 吴兆辉; 李亚伟; 李昕熠; 高宗智
Original assignee: 华为技术有限公司
Priority date: 2020-10-27
Filing date: 2020-10-27
Publication date: 2022-05-05
Also published as: CN116210152A

Abstract

Provided are a resonator and a manufacturing method therefor, a filter, and an electronic device, relating to the field of resonators, and being capable of suppressing spurious harmonics of a resonator. The resonator comprises: a piezoelectric substrate, and an interdigital transducer arranged on the piezoelectric substrate. The piezoelectric substrate comprises, stacked in sequence, a substrate, a reflective layer, and a piezoelectric layer. The interdigital transducer comprises a first bus bar, a second bus bar, and multiple interdigital electrodes that are first interdigital electrodes and second interdigital electrodes alternately arranged in parallel between the first bus bar and the second bus bar. The first interdigital electrodes are connected to the first bus bar, and the second interdigital electrodes are connected to the second bus bar. The resonator also comprises first reflection grooves provided on the piezoelectric substrate. The first reflection grooves are positioned in the area between the first interdigital electrodes and the second bus bar.

Description

Resonator and its manufacturing method, filter, electronic equipment

technical field

The present application relates to the field of resonators, and in particular, to a resonator and a manufacturing method thereof, a filter, and an electronic device.

Background technique

Many spurs often appear on the admittance curve of a resonator, and these spurs will affect the performance of the resonator, thereby causing the in-band ripple of the filter composed of the resonator and deteriorating the passband performance.

SUMMARY OF THE INVENTION

Embodiments of the present application provide a resonator and a method for manufacturing the same, a filter, and an electronic device, which can reduce the stray of the resonator.

An embodiment of the present application provides a resonator, including: a piezoelectric substrate and an interdigital transducer disposed on the piezoelectric substrate; wherein the piezoelectric substrate includes a substrate, a reflective layer, and a piezoelectric layer that are stacked in sequence The interdigital transducer includes: a first bus bar, a second bus bar, and a plurality of interdigital electrodes arranged in parallel between the first bus bar and the second bus bar; the parallel arrangement direction of the plurality of interdigital electrodes is the first direction; along the vertical first direction, the first bus bar and the second bus bar are distributed on both sides of the plurality of interdigitated electrodes; the plurality of interdigitated electrodes include first interdigitated electrodes and second interdigitated electrodes alternately arranged in sequence an interdigitated electrode; the first interdigitated electrode is connected to the first bus bar, and the second interdigitated electrode is connected to the second bus bar; the resonator further comprises: a first reflection groove arranged on the piezoelectric substrate; the first reflection groove is located in the The area between the first interdigitated electrode and the second bus bar.

By arranging the first reflection groove between the tip of the first interdigital electrode and the second bus bar, the transverse mode wave will encounter the boundary of the first reflection groove (that is, the side close to the first interdigital electrode). boundary), reflection will occur due to the mismatch of acoustic impedance, and the reflection phase can be close to zero in a large frequency range, thus forming a free boundary condition, thereby suppressing the transverse mode in the admittance characteristic at the resonant frequency (fr) and the inverse frequency (fr) The amplitude of the fluctuations generated between the resonant frequencies (fa) (ie, suppressing the lateral modal spurs of the resonator) to reduce the spurs.

In some possible implementation manners, the resonator further includes: a second reflection groove disposed on the piezoelectric substrate; the second reflection groove is located in a region between the second interdigital electrode and the first bus bar.

By arranging a second reflection groove between the tip of the second interdigital electrode and the first bus bar, in this way, the transverse mode wave encounters the boundary of the second reflection groove (that is, the side close to the first interdigital electrode). boundary), reflection will occur due to the mismatch of acoustic impedance, and the reflection phase can be close to zero in a large frequency range, thus forming a free boundary condition, thereby suppressing the transverse mode in the admittance characteristic at the resonant frequency (fr) and the inverse frequency (fr) The amplitude of the fluctuations generated between the resonant frequencies (fa) (ie, suppressing the lateral modal spurs of the resonator) is used to further reduce the spurs.

In addition, in the case where the tips of the first interdigital electrode and the second interdigital electrode are both provided with reflection grooves (that is, the first reflection groove and the second reflection groove are provided at the same time), the transverse mode wave is in the first reflection groove and the second reflection groove. The boundary position of the reflection groove forms the sound wave reflected back and forth between the two free boundaries to form a standing wave, and the antinode of the standing wave is located on the boundary, which balances the charge distribution of the transverse mode and achieves the broadband piston mode (BPM), Further, the fluctuation amplitude of the transverse mode between the resonant frequency and the anti-resonant frequency of the admittance characteristic is suppressed (that is, the lateral mode spur of the resonator is suppressed), thereby ensuring that the resonator is at the resonant frequency and the anti-resonant frequency. There is a relatively smooth admittance curve between them.

In some possible implementation manners, along the first direction (the parallel arrangement direction of the plurality of interdigitated electrodes), the size of the first reflective groove is larger than the width of the first interdigitated electrode; to ensure that the boundary of the first reflective groove is It can improve the reflection efficiency of transverse mode waves and improve the reflection coefficient of the resonator.

In some possible implementations, along the first direction (the parallel arrangement direction of the plurality of interdigitated electrodes), the size of the second reflective groove is larger than the width of the second interdigitated electrode; to ensure that the boundary of the second reflective groove is It can improve the reflection efficiency of transverse mode waves and improve the reflection coefficient of the resonator.

In some possible implementation manners, the included angle between the side wall of the first reflection groove on the side close to the first interdigital electrode and the vertical line (normal line) of the piezoelectric substrate is 0° to 20°; to ensure the lateral mode The reflection coefficient amplitude of the wave at the boundary of the first reflection slot is close to 1, and the phase is close to 0°.

In some possible implementation manners, the included angle between the side wall of the second reflection groove on the side close to the second interdigital electrode and the vertical line (normal line) of the piezoelectric substrate is 0-20°; to ensure the lateral mode The reflection coefficient amplitude of the wave at the boundary of the second reflection slot is close to 1 and the phase is close to 0°.

In some possible implementation manners, the sidewall of the first reflection groove on the side close to the first interdigital electrode is perpendicular to the piezoelectric substrate. In this case, when the transverse mode wave encounters the boundary at the position of the first reflection slot, the amplitude of the acoustic wave reflection coefficient is the highest, and the energy leaking to the outside (outside the bus bar) is the least, so that the quality factor of the resonator can be improved.

In some possible implementation manners, the sidewall of the second reflection groove on the side close to the second interdigital electrode is perpendicular to the piezoelectric substrate. In this case, when the transverse mode wave encounters the boundary at the position of the second reflection slot, the amplitude of the acoustic wave reflection coefficient is the highest, and the energy leaking to the outside (outside the bus bar) is the least, so that the quality factor of the resonator can be improved.

In some possible implementation manners, the distance between the sidewall of the first reflection groove on the side close to the first interdigital electrode and the first interdigital electrode is 0-2 μm. In this case, by setting the distance between the side wall of the first reflection groove on the side close to the first interdigital electrode and the first interdigital electrode close to 0, it is ensured that the incident wave and the reflected wave are at the tip of the first interdigital electrode. The phase difference at is close to 0° to ensure the suppression of transverse mode waves.

In some possible implementation manners, the distance between the sidewall of the second reflection groove on the side close to the second interdigital electrode and the second interdigital electrode is 0-2 μm. In this case, by setting the distance between the side wall of the second reflection groove on the side close to the second interdigital electrode and the second interdigital electrode close to 0, it is ensured that the incident wave and the reflected wave are at the tip of the second interdigital electrode. The phase difference at is close to 0° to ensure the suppression of transverse mode waves.

In some possible implementations, the first reflection groove and the second reflection groove are strip-shaped grooves, and the extending direction of the strip-shaped grooves is perpendicular to the interdigital electrodes.

In some possible implementations, the first reflection groove and the second reflection groove are cross-shaped grooves; the cross-shaped groove includes: intersecting first strip-shaped grooves and second strip-shaped grooves; an extension direction of the first strip-shaped grooves Perpendicular to the interdigital electrodes, the extending direction of the second strip-shaped groove is parallel to the interdigital electrodes.

In some possible implementations, the first reflective groove penetrates the piezoelectric layer and the partially reflective layer.

In some possible implementations, the first reflection groove penetrates through the piezoelectric layer and all the reflection layers, that is, the depth of the first reflection groove is equal to the sum of the thicknesses of the reflection layer and the piezoelectric layer; in order to reduce the transverse mode wave in the first reflection groove The energy radiation at the boundary leaks, and the reflection angle is closer to the ideal 0° in a wide frequency band, improving the quality factor of the resonator.

In some possible implementations, the second reflective groove penetrates the piezoelectric layer and the partially reflective layer.

In some possible implementations, the second reflection groove penetrates through the piezoelectric layer and all the reflection layers, that is, the depth of the second reflection groove is equal to the sum of the thicknesses of the reflection layer and the piezoelectric layer; in order to reduce the transverse mode wave in the first reflection groove The energy radiation at the boundary leaks, and the reflection angle is closer to the ideal 0° in a wide frequency band, improving the quality factor of the resonator.

In some possible implementations, the polarization direction of the piezoelectric material in the piezoelectric layer adopts the X-tangent direction or the Y-tangent direction, so as to improve the electromechanical coupling coefficient (k ² ) of the resonator.

In some possible implementations, the direction of shear displacement of the piezoelectric layer includes a principal component along the first direction.

In some possible implementations, the first reflection groove and the second reflection groove are filled with at least one of silicon dioxide and silicon nitride.

The embodiments of the present application provide a filter, including the resonator provided in any of the foregoing possible implementation manners. In this filter, the lateral modal spurs of the acoustic wave generated by the resonator can be suppressed, so that the resonant frequency and the anti-resonant frequency of the resonator have a relatively smooth admittance curve, which greatly reduces the passband of the filter. Ripple, referring to the passband performance of the filter.

An embodiment of the present application provides an electronic device, including a transceiver, a memory, and a processor; wherein the transceiver is provided with a filter provided in any of the foregoing possible implementation manners.

Embodiments of the present application provide a method for manufacturing a resonator, including:

A reflective layer and a piezoelectric layer are sequentially formed on the substrate; an interdigital transducer is formed on the surface of the piezoelectric layer; a protective film is formed on the surface of the interdigital transducer, and a hollow pattern is formed on the protective film; The position of the pattern is located in the area where the bus bar in the interdigital transducer is opposite to the interdigital electrode; at the position of the hollow pattern, the piezoelectric substrate is etched to form a reflection groove.

In the resonator manufactured by the manufacturing method provided in the embodiment of the present application, a reflection groove is formed between the tip of the interdigital electrode and the bus bar, so that when the transverse mode wave encounters the boundary of the reflection groove, due to the mismatch of acoustic impedance, the Reflection occurs, and the reflection phase can be close to zero in a large frequency range, thus forming a free boundary condition, thereby suppressing the fluctuation amplitude of the transverse mode between the resonant frequency and the anti-resonant frequency of the admittance characteristic (that is, suppressing the lateral modal spurs of the resonator).

Description of drawings

FIG. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present application;

2 is a schematic structural diagram of a resonator provided by an embodiment of the present application;

3 is a schematic partial structure diagram of a resonator provided in an embodiment of the present application;

4 is a schematic cross-sectional view of a resonator provided in an embodiment of the present application;

5 is a schematic cross-sectional view of a resonator according to an embodiment of the present application;

6 is a schematic structural diagram of a resonator provided by an embodiment of the present application;

7 is a schematic diagram of a partial structure of a resonator provided in the related art of the present application;

Fig. 8a is a comparison diagram of admittance curves of a resonator provided in an embodiment of the application and a resonator provided in the related art;

FIG. 8b is a comparison diagram of admittance curves of a resonator provided in an embodiment of the application and a resonator provided in the related art;

FIG. 8c is a comparison diagram of admittance curves of a resonator provided in an embodiment of the application and a resonator provided in the related art;

FIG. 8d is a comparison diagram of admittance curves of a resonator provided in an embodiment of the application and a resonator provided in the related art;

Fig. 9a is a kind of resonator that the embodiment of the application provides and the Q value curve comparison diagram of a kind of resonator provided in the related art;

9b is a comparison diagram of the Q value curve of a resonator provided in an embodiment of the application and a resonator provided in the related art;

FIG. 9c is a comparison diagram of the Q value curve of a resonator provided in an embodiment of the application and a resonator provided in the related art;

FIG. 9d is a comparison diagram of the Q value curve of a resonator provided in an embodiment of the application and a resonator provided in the related art;

10 is a flowchart of a method for manufacturing a resonator provided in an embodiment of the application;

11 is a schematic diagram of a manufacturing process of a resonator provided by an embodiment of the application;

12 is a schematic diagram of a manufacturing process of a resonator according to an embodiment of the present application;

13 is a schematic diagram of a manufacturing process of a resonator according to an embodiment of the present application;

14 is a schematic diagram of a manufacturing process of a resonator provided by an embodiment of the application;

FIG. 15 is a schematic structural diagram of a filter provided by an embodiment of the present application.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly described below with reference to the accompanying drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, and Not all examples. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

The terms "first", "second", etc. in the description, embodiments and claims of the present application and the drawings are only used for the purpose of distinguishing and describing, and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implied order. "Connected", "connected" and similar words are used to express the intercommunication or interaction between different components, and may include direct connection or indirect connection through other components. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, eg, comprising a series of steps or elements. A method, system, product or device is not necessarily limited to those steps or units expressly listed, but may include other steps or units not expressly listed or inherent to the process, method, product or device. "Top", "bottom", "left", "right", etc. are only used relative to the orientation of components in the drawings, these directional terms are relative concepts, and they are used for relative description and clarification , which may vary according to the orientation in which the components in the figures are placed.

An embodiment of the present application provides an electronic device, wherein a filter is provided in the electronic device, so as to suppress interference signals through the filter, so as to achieve the purpose of filtering.

This application does not limit the specific setting form of the electronic device, for example, the electronic device may be a television, a mobile phone, a satellite communication device, a cable television, or the like.

Illustratively, in some possible implementation manners, as shown in FIG. 1 , the foregoing electronic device 01 may include a transceiver 100, a memory 200 and a processor 300 (which may be a local processor or a cloud processor); wherein, The transceiver 100 is provided with a filter 101, and the filter 101 is constructed by using a resonator.

In the filter of the present application, the transverse mode (TM) of the acoustic wave generated by the resonator can be suppressed, so that there is a relatively smooth admittance between the resonant frequency (fr) and the anti-resonance frequency (fa) of the resonator The curve reduces the ripple in the passband of the filter and improves the passband performance of the filter.

The specific setting of the resonator provided in the embodiment of the present application will be further described below.

As shown in FIG. 2 , the resonator includes a piezoelectric substrate 1 and an interdigital transducer (IDT) 2 disposed on the piezoelectric substrate 1; the interdigital transducer is an important part of the resonator , for the realization of acoustic-electrical conversion.

The above-mentioned piezoelectric substrate 1 includes a substrate 11, a reflective layer 12, and a piezoelectric layer 13 that are stacked in sequence; the reflective layer 12 may include alternately stacked low acoustic resistance layers a1 and high acoustic resistance layers a2; in this case, The resonator may also be referred to as a solid mounted resonator (SMR).

Exemplarily, in the above reflection layer 12, the low acoustic resistance layer a1 can be made of a low acoustic resistance dielectric material, such as silicon dioxide (SiO ₂ ), silicon nitride (SiN), etc.; the high acoustic resistance layer a2 can be made of a high acoustic resistance material. Among them, metal materials with high acoustic resistance can be used such as tungsten (W), molybdenum (Mo), etc.; dielectric materials with high acoustic resistance can be used such as aluminum nitride (AlN), tantalum pentoxide (Ta ₂ O ₅ ) and the like.

As shown in FIG. 2 , the interdigital transducer 2 includes: a first bus bar 21 , a second bus bar 22 , and a plurality of interdigital electrodes juxtaposed between the first bus bar 21 and the second bus bar 22 . T; wherein, the interdigitated electrodes T are arranged side by side in the first direction xx', the interdigitated electrodes T extend along the second direction yy', and the first direction xx' and the second direction yy' are perpendicular, and the first bus bars 21, The second bus bar 22 extends along the first direction xx'.

In the second direction yy', the first bus bars 21 and the second bus bars 22 are distributed on both sides of the plurality of interdigitated electrodes T; the plurality of interdigitated electrodes T include a plurality of first interdigitated electrodes 31 and a plurality of interdigitated electrodes T. two second interdigital electrodes 32, the first interdigitated electrodes 31 and the second interdigitated electrodes 32 are alternately arranged along the first direction xx'; that is, any two adjacent interdigitated electrodes in the plurality of interdigitated electrodes T In T, one is the first interdigitated electrode 31 and the other is the second interdigitated electrode 32 ; wherein the first interdigitated electrode 31 is connected to the first bus bar 21 , and the second interdigitated electrode 32 is connected to the second bus bar 22 connect.

In addition, with the advent of the era of 5G (5th generation mobile networks, the fifth generation mobile communication technology), in order to ensure that the resonator has high frequency and large bandwidth frequency bands (such as N77, N78, N79) and high electromechanical coupling coefficient (k ² ) In some possible implementations, the frequency range corresponding to the thickness shear mode (TSM) of the resonator can be used, that is, the vibration mode of the piezoelectric layer 13 is in the thickness shear mode. Corresponding frequency range to obtain higher operating frequency and larger electromechanical coupling coefficient (k ² ).

On this basis, in some possible implementations, the shear displacement direction of the piezoelectric layer 13 includes a principal component along the first direction xx′, that is, the shear displacement direction of the piezoelectric layer 13 includes a plurality of forks along the direction of the shear displacement. Refers to the main component in the juxtaposed direction of the electrodes T; for example, in some possible implementations, the shear displacement direction of the piezoelectric layer 13 is the first direction xx'.

Of course, in order to further improve the electromechanical coupling coefficient (k ² ) of the resonator, in some possible implementations, the polarization direction of the piezoelectric material in the piezoelectric layer 13 in the resonator 100 can be the X-tangent direction or Y tangent direction; for example, the piezoelectric material in the piezoelectric layer a3 can be at least one of lithium niobate (LiNbO ₃ ) and lithium tantalate (LiTaO ₃ ); the polarization directions of LiNbO ₃ and LiTaO ₃ can be X Tangent direction or Y tangent direction.

It can be understood that the polarization direction of the above piezoelectric material can be the X-tangent direction or the Y-tangent direction. Taking LiNbO3 as the piezoelectric material in the piezoelectric layer ₁₃ as an example, referring to FIG. 2, set The crystal axis (X, Y, Z) of LiNbO ₃ defines a rectangular coordinate system (xyz), the x axis is the first direction xx', the y axis is the second direction yy', and the z axis is the surface normal of the piezoelectric substrate 1 direction, that is, the direction perpendicular to the xx'-yy'plane; in this case, the polarization direction of LiNbO ₃ adopts the X-tangent direction, which means that the X crystal axis of LiNbO ₃ faces the direction of the z-axis (as shown in Figure 2 ), the polarization direction of LiNbO ₃ adopts the Y-tangent direction, which means that the Y crystal axis of LiNbO ₃ faces the direction of the z-axis.

In addition, the present application does not specifically limit the direction of the chamfering angle of the crystal orientation of the piezoelectric material, which can be set according to the specific piezoelectric material and requirements in practice. Referring to FIG. 2 , taking LiNbO ₃ as the piezoelectric material in the piezoelectric layer 13 as an example, in this case, the z-axis direction can be the X crystal axis, the Y crystal axis, or the Y crystal axis of LiNbO ₃ rotated by 30°, etc. direction; when the crystallographic tangent angle _of LiNbO3 is the X crystal axis, the crystallographic axis of LiNbO3 along the x _- axis can be the Y crystallographic axis; when the crystallographic tangent angle _of LiNbO3 is the Y crystallographic axis, the LiNbO3 along the x _- axis The crystallographic axis can be the X crystallographic axis.

Referring to FIG. 2 , the resonator further includes: a first reflection groove 41 disposed on the piezoelectric substrate 1 ; wherein, the first reflection groove 41 is located in the region between the first interdigital electrode 31 and the second bus bar 22 . In this case, when the resonator operates at the frequency corresponding to the thickness shear mode, when the transverse mode wave encounters the boundary of the first reflection slot (that is, the boundary on the side close to the first interdigital electrode), due to The acoustic impedance mismatch will cause reflection, and the reflection phase can be close to zero in a large frequency range, thus forming a free boundary condition, which in turn suppresses the transverse mode in the admittance characteristic at the resonant frequency (fr) and the anti-resonance frequency (fa) The amplitude of the fluctuation generated between them (that is, reducing the spurs of the resonator).

Of course, in some possible implementations, as shown in FIG. 2 , the resonator may further include a second reflection groove 42 , and the second reflection groove 42 is located between the second interdigital electrode 32 and the first bus bar 21 . area. In this case, when the resonator operates at the frequency corresponding to the thickness shear mode, when the transverse mode wave encounters the boundary of the second reflection slot (that is, the boundary on the side close to the first interdigital electrode), due to The acoustic impedance mismatch will cause reflection, and the reflection phase can be close to zero in a large frequency range, thus forming a free boundary condition, which in turn suppresses the transverse mode in the admittance characteristic at the resonant frequency (fr) and the anti-resonance frequency (fa) The amplitude of the fluctuation generated between them (that is, reducing the spurs of the resonator).

In the resonator of the present application, by arranging reflective grooves (first reflective grooves, second reflective grooves) between the tips of the interdigital electrodes and the bus bars, when the resonator operates in the thickness shear mode, the transverse mode The acoustic wave reflected back and forth between the two free boundaries formed by the first reflection slot and the second reflection slot forms a standing wave, and the antinode of the standing wave is located on the boundary, which balances the charge distribution of the transverse mode and achieves a broadband piston mode ( broadband piston mode, BPM), thereby suppressing the fluctuation amplitude of the transverse mode in the admittance characteristic between the resonant frequency (fr) and the anti-resonant frequency (fa) (that is, reducing the frequency corresponding to the transverse mode of the resonator). Spurs in the range), thus making the resonator have a smoother admittance curve between the resonant frequency and the anti-resonant frequency.

It should be noted that, in FIG. 2 , the first reflection groove 41 is provided in the area between each of the first interdigitated electrodes 31 and the second bus bar 22 , and each of the second interdigitated electrodes 32 is connected to the second bus bar 22 . The area between a bus bar 21 may be provided with the second reflection groove 42 as an example for illustration; in some possible implementations, only a part of the first interdigital electrode 31 and the second bus bar 22 may be provided. The first reflection grooves 41 are provided in the area of the 21; in some possible implementation manners, the second reflection grooves 42 may also be provided only in a part of the area between the second interdigital electrode 32 and the first bus bar 21 .

In the following embodiments, a first reflection groove 41 is provided in the area between each of the first interdigitated electrodes 31 and the second bus bar 22 , and the area between each of the second interdigitated electrodes 32 and the first bus bar 21 is provided with a first reflection groove 41 . The second reflection grooves 42 are provided in all regions as an example to illustrate the present application.

In order to ensure that the resonator reflects the transverse mode wave at the boundary of the reflection grooves (41, 42), the reflection coefficient (the amplitude of the reflected wave/the amplitude of the incident wave) is increased; On the basis, the size of the first reflection groove 41 is increased as much as possible; on the basis of not exceeding the distance between two adjacent first interdigital electrodes 41, the size of the second reflection groove 42 is increased as much as possible. As shown in FIG. 3 (a partial schematic diagram of the resonator in FIG. 2 ), in some possible implementations, in the first direction xx′, the size d1 of the first reflection groove 41 may be set larger than that of the first interdigital electrode 31 The width d2 of the second reflective groove 42 is larger than the width d4 of the second interdigital electrode (ie, d3>d4).

Illustratively, in some possible implementations, the width d2 of the first interdigitated electrode 31 and the width d4 of the second interdigitated electrode 32 may be the same (ie, d2=d4), and the first reflection groove 41 is along the first direction xx′ The dimension d1 of the second reflection groove 42 along the first direction xx' may be the same (ie, d1=d3).

On this basis, the distance of the wave travel determines whether the phase difference between the incident wave and the reflected wave at the tip of the interdigital electrode is close to 0°. There is a phase shift with the reflected wave in this stroke, so in practice, it is generally possible to reduce the distance from the side wall of the reflection groove (41, 42) on the side close to the interdigital electrode (31, 32) to the interdigital electrode (31, 42) as much as possible. 32) to reduce the phase difference between the incident wave and the reflected wave at the tip of the interdigital electrode.

Based on this, the first reflective groove 41 can be disposed adjacent to the side wall S1 on the side close to the first interdigitated electrode 31 and the first interdigitated electrode 41 . However, considering the error of the manufacturing process, as shown in FIG. 4 (a partial cross-sectional schematic diagram of the resonator in FIG. 2 ), the sidewall S1 of the first reflection groove 41 on the side close to the first interdigital electrode 31 is connected to the first interdigital electrode 31 . The distance between 41 is set to be 0-2 μm; in this case, it can be considered that the first reflection groove 41 is adjacent to the side wall S1 on the side close to the first interdigital electrode 31 and the first interdigitated electrode 41 set up.

It should be noted that, for the distance between the side wall S1 of the first reflection groove 41 on the side close to the first interdigital electrode 31 and the first interdigital electrode 41 of 0-2 μm, as shown in FIG. 4 , In some cases, the sidewall S1 of the first reflection groove 41 is located below the first interdigital electrode 41 on the side close to the first interdigital electrode 31 , and the sidewall S1 is connected to the end of the first interdigital electrode 41 (also far away from the first interdigital electrode 41 ). The distance between the edges S2 of one end of the first bus bar 21) is within 2 μm; in some cases, the sidewall S1 of the first reflection groove 41 on the side close to the first interdigital electrode 31 is located at the first interdigital electrode 41 The side wall (ie the side face away from the first bus bar 21 ), and the distance between the side wall S1 and the edge S2 of the end of the first interdigital electrode 41 is within 2 μm.

In addition, referring to FIG. 5, it can be understood that due to the inclination angle β of the side wall S1 of the reflection grooves (41, 42) on the side close to the interdigital electrodes (31, 32) (that is, the first reflection groove 41 is close to the The angle between the side wall S1 on the side of the first interdigital electrode 31 and the vertical line L1 of the piezoelectric substrate 1 ) determines the reflection coefficient of the incident acoustic wave and the reflected acoustic wave at the free boundary. The magnitude of the coefficient decreases, and the phase angle deviates from 0° rapidly with frequency, which is not conducive to the suppression of the transverse mode.

Based on this, in order to ensure that the amplitude of the reflection coefficient of the transverse mode wave at the edge is close to 1 and the phase is close to 0°, as shown in FIG. 5 , in some possible implementations, the first reflection slot 41 can be set close to the first The inclination angle β of the side wall S1 on the side of the interdigital electrode 31 is 0 to 20°.

It should be noted that, for the inclination angle β of the side wall S1 of the first reflection groove 41 on the side close to the first interdigital electrode 31 is 0° to 20°, in some cases, the side wall S1 may face the outside of the slot. For inclination (as shown in FIG. 5 ), the inclination angle is 0-20°; in some cases, the side wall S1 may be inclined toward the inner side of the slot, and the inclination angle is 0-20°.

In some possible implementations, in the case where the inclination angle of the side wall S1 of the side of the first reflection groove 41 close to the first interdigital electrode 31 is 0° (or approximately 0°) (refer to FIG. 4 ), That is, when the side wall S1 of the first reflection groove 41 close to the first interdigital electrode 31 is perpendicular to the piezoelectric substrate 1, when the transverse mode wave encounters the boundary of the first reflection groove, the amplitude of the acoustic wave reflection coefficient is The highest, the least energy leaks to the outside (outside the bus bar), which can improve the quality factor (ie Q value) of the resonator.

Similarly, referring to FIG. 3 , in some possible implementations, the distance between the sidewall of the second reflection groove 42 on the side close to the second interdigital electrode 32 and the second interdigital electrode 32 is 0˜2 μm; Reference may be made to the foregoing description that the distance between the sidewall S1 of the first reflection groove 41 on the side close to the first interdigital electrode 31 and the first interdigital electrode 31 is 0-2 μm, which will not be repeated here.

Similarly, referring to FIG. 3 , in some possible implementations, the inclination angle of the sidewall of the second reflective groove 42 close to the second interdigital electrode 32 (ie, the angle between the sidewall and the vertical line L1 of the piezoelectric substrate 1 ) angle) is 0-20°; for details, reference may be made to the foregoing description about the inclination angle of the side wall S1 of the first reflection groove 41 on the side close to the first interdigital electrode 31 being 0-20°, which will not be repeated here.

Illustratively, in some possible implementations, the inclination angle of the side wall of the second reflection groove 42 on the side close to the second interdigital electrode 32 may be set to 0° (or approximately 0°), that is, the second reflection groove 42 The side wall on the side close to the second interdigital electrode 32 is perpendicular to the piezoelectric substrate 1 .

In addition, the present application does not limit the specific arrangement shape of the above-mentioned reflection grooves (41, 42), which can be arranged according to actual needs.

In some possible implementations, as shown in FIG. 3 , the first reflection groove 41 and the second reflection groove 42 may be strip-shaped grooves, and the extension direction of the strip-shaped grooves is the same as that of the interdigital electrodes ( 31 , 32 ). The direction is vertical, that is, the strip groove extends along the first direction xx'. Illustratively, the width of the strip-shaped groove (that is, the dimension along the second direction yy') may be between 0.1 μm and 20 μm.

In some possible implementations, as shown in FIG. 6 , the first reflection grooves 41 and the second reflection grooves 42 may be cross-shaped grooves; the cross-shaped grooves include: crossed first strip-shaped grooves c1 and second strip-shaped grooves Slot c2; the extending direction of the first strip-shaped slot c1 is perpendicular to the interdigital electrodes (31, 32) (that is, extending along the first direction xx'), and the extending direction of the second strip-shaped slot c2 is perpendicular to the interdigital electrodes (31, 32). 32) Parallel (ie extending in the second direction yy').

In some possible implementations, the reflection grooves (41, 42) may be filled with a low acoustic resistance material, and the low acoustic resistance material may include at least one of silicon dioxide (SiO ₂ ) and silicon nitride (SiN), However, it is not limited to this. In practice, other suitable low acoustic resistance materials can be selected as required.

In some possible implementations, the reflection grooves (41, 42) may be filled with air.

In addition, the present application does not specifically limit the depths of the reflection grooves (41, 42); for example, the depths of the first reflection grooves 41 and the second reflection grooves 42 may be the same or different; the depths of different first reflection grooves 41 may be different. They can be the same or different; the depths of different second reflection grooves can be the same or different; in practice, the depths of the reflection grooves (41, 42) can be selected according to needs.

Of course, it can be understood that the larger the depth of the reflection grooves (41, 42) is, the more energy radiation leakage can be reduced, the quality factor of the resonator can be improved, and the reflection angle is closer to the ideal 0° in a wide frequency band; therefore, In practice, the depth of the reflection grooves (41, 42) can be increased as much as possible. For example, as shown in Figures 4 and 5, the reflection grooves (41, 42) can be set to penetrate through the reflection layer 12 and the piezoelectric layer 13; That is, the depth of the reflection grooves ( 41 , 42 ) is equal to the sum of the thicknesses of the piezoelectric layer 13 and the reflection layer 12 . Of course, in some possible implementations, the reflection grooves (41, 42) can also be arranged to penetrate through the piezoelectric layer 13 and the partial reflection layer 12, that is, the depth of the reflection grooves (41, 42) is equal to the piezoelectric layer 13 and the partial reflection layer 12. The sum of the thicknesses of the layers 12 .

The following is a comparison of the admittance curve and the Q value curve of the resonator provided with the reflection grooves (41, 42) provided by the embodiment of the present application under different aperture lengths, and the related art provides the mass at both ends of the interdigital electrode T. The admittance curve and Q value curve of the resonator (refer to FIG. 7 ) loaded with structure p are compared and explained.

The solid line curves in FIGS. 8a, 8b, 8c, and 8d are respectively the admittance curves of the resonators using reflection grooves under the apertures of 1λ, 3λ, 5λ, and 10λ provided by the embodiment of the present application. The dashed curves in Fig. 8b, Fig. 8c, Fig. 8d are the admittance curves of the resonator (Fig. 7) using the mass-loading structure p under the apertures of 1λ, 3λ, 5λ, and 10λ provided in the related art, respectively; wherein, λ is equal to the spacing between two adjacent interdigital electrodes connected to the same bus bar.

It can be seen from Fig. 8a, Fig. 8b, Fig. 8c, Fig. 8d that, under the same aperture, compared with the admittance curve of the resonator of the mass-loading structure p adopted in the related art, the embodiment of the present application provides a The admittance curve of the resonators of the reflection grooves (41, 42) is smoother between the resonance frequency (fr) and the anti-resonance frequency (fa), that is, the effect of suppressing the transverse mode is better. 8a, 8b, 8c, and 8d, it can be seen that the admittance curve of the resonator provided with the reflection grooves (41, 42) provided by the embodiment of the present application increases with the aperture (1λ, 3λ, 5λ) , 10λ), the smoothness of the admittance curve of the resonator at the resonant frequency (fr) and the anti-resonant frequency (fa) is improved, that is, with the increase of the aperture, the suppression effect on the transverse mode is better.

The solid line curves in FIGS. 9a, 9b, 9c, and 9d are respectively the Q value (that is, the quality factor) of the resonator using the reflection groove under the apertures of 1λ, 3λ, 5λ, and 10λ provided by the embodiment of the present application. ) curve; the dashed curves in Fig. 9a, Fig. 9b, Fig. 9c, Fig. 9d are the resonators (Fig. 7) using the mass-loading structure p under the apertures of 1λ, 3λ, 5λ, and 10λ provided in the related art, respectively. Q-value curve.

It can be seen from Fig. 9a, Fig. 9b, Fig. 9c, Fig. 9d that, under the same aperture, the Q value of the resonator provided with the reflection grooves (41, 42) provided in the embodiment of the present application is greater than that used in the related art The Q value of the resonator of the mass-loaded structure p, that is, the resonator provided in the embodiment of the present application suppresses the lateral stray mode of the resonator in a wide frequency range through the setting of the reflection slot, reduces the lateral energy leakage, and improves the resonance The Q value of the resonator is improved, so that the performance of the resonator is better than that of the resonator of the mass loading structure p adopted in the related art.

In addition, for the reflection grooves (41, 42) in this application, it should be understood that the sidewalls of the reflection grooves on the side away from the interdigital electrodes hardly inhibit the lateral mode. The specific arrangement of the sidewall on the side of the concave reflection groove away from the interdigital electrode is not limited.

The following provides a method for manufacturing a solid-state reflective resonator (SMR) according to an embodiment of the present application. As shown in FIG. 10 , the manufacturing method may include:

Step 01 , as shown in FIG. 11 , the reflective layer 12 and the piezoelectric layer 13 are sequentially formed on the substrate 11 to obtain the piezoelectric substrate 1 .

Illustratively, step 01 may include: depositing a tungsten metal thin film (as a high acoustic resistance layer a2) on a silicon substrate (11), and performing chemical mechanical polishing (chemical mechanical polishing, CMP) on the surface of the tungsten metal thin film; A silicon dioxide film (as a low acoustic resistance layer a2) is deposited on the surface of the tungsten metal film, and chemical mechanical polishing is performed on the surface of the silicon dioxide film; next, a tungsten metal film (as a high acoustic resistance layer a2) is deposited again, and Chemical mechanical polishing is performed on the surface of the tungsten metal film; silicon dioxide film (as the low acoustic resistance layer a1 ) is deposited again, and chemical mechanical polishing is performed on the surface of the silicon dioxide film to complete the fabrication of the reflective layer 12 .

By implanting He+ ions into the lithium niobate wafer (ie, the piezoelectric wafer), a He+ implanted intermediate film layer is formed in the lithium niobate wafer, and the lithium niobate wafer after the He+ ion implantation is bonded to the reflective layer 12 Then, the ion He+ implanted into the lithium niobate wafer is formed into He ₂ by heat treatment technology, and the lithium niobate wafer located on the side of the He+ implanted interlayer film away from the reflective layer 12 is peeled off and kept in the reflective layer 12 The lithium niobate film on the surface is used as the piezoelectric layer 13 ; thus, the fabrication of the piezoelectric substrate 1 is completed.

Step 02 , as shown in FIG. 12 , a metal thin film is formed on the surface of the piezoelectric layer 13 , and the metal thin film is patterned to form the interdigital transducer 2 .

Illustratively, the above step 02 may include: sputtering a metal thin film on the surface of the piezoelectric layer 13 , and patterning the metal thin film by ion beam etching (IBE) to form the interdigital transducer 2 . Referring to FIG. 2 , the interdigital transducer 2 includes interdigital electrodes (31, 32), bus bars (21, 22), and the like.

Step 03. Referring to (a) and (b) of FIG. 13, a protective film 14 is formed on the surface of the interdigital transducer 2, and a hollow pattern H is formed on the protective film 14; wherein, the position of the hollow pattern H is The area where the bus bars ( 21 , 22 ) in the interdigital transducer 2 are opposite to the interdigital electrodes ( 31 , 32 ); that is, the area of the first reflection groove 41 and the second reflection groove 42 in FIG. 2 .

Illustratively, the above step 03 may include: forming a silicon dioxide film (14) on the surface of the interdigital transducer 2, and forming a hollow pattern H on the silicon dioxide film (14) corresponding to the position where the reflection groove is to be formed (may also be referred to as an air gap pattern).

Step 04 , as shown in FIG. 14 ( a ), at the position of the hollow pattern H, the piezoelectric substrate 1 is etched to form the reflection groove 40 .

Illustratively, the reflection groove 40 may include a first reflection groove 41 and a second reflection groove 41; for the arrangement of the first reflection groove 41 and the second reflection groove 41, reference may be made to FIG. 2 and the relevant descriptions in the foregoing embodiments, here No longer.

Schematically, as shown in (a) of FIG. 14 , the above step 04 may include: at the position of the hollow pattern H, the lithium niobate film (13), the oxide film (13), the lithium niobate film (13), the oxide The silicon thin film (a1) and the tungsten metal thin film (a2) are etched to form the reflection groove 40 . After the reflection groove 40 is formed, as shown in FIG. 14(b), the manufacturing method may further include: removing the silicon dioxide film (14) located on the surface of the interdigital transducer 2; of course, in this case, you can The silicon dioxide film (a1) at the bottom of the reflection groove 40 is removed.

For other related contents in the above-mentioned embodiments of the resonator manufacturing method, such as the shape and size of the reflection groove, you can refer to the corresponding parts in the above-mentioned resonator structure embodiments, which will not be repeated here; The related structure in the example can be manufactured correspondingly with reference to the above-mentioned embodiment of the manufacturing method of the resonator, or can be manufactured with appropriate adjustment in combination with the related technology, which is not limited in this application.

It can be seen from the foregoing that the resonator provided by the embodiment of the present application has low difficulty in manufacturing and processing, and the resonator provided by the embodiment of the present application suppresses the lateral mode through the reflection slot, constrains the acoustic wave energy to the main mode, and improves the coupling of the resonator. coefficients and Q values, especially for wideband filters. In addition, the resonator provided in the embodiment of the present application can realize a narrow aperture design, so that the size of the filter can be further reduced, and has certain advantages in miniaturization.

The present application does not limit the type of the filter constructed by using the resonator provided in any of the foregoing possible implementation manners; for example, it may be a filter with a ladder structure.

Illustratively, the present application provides a filter. As shown in FIG. 15 , the filter may include an input terminal IN, an output terminal OUT, a series branch B1, and at least one parallel branch B2. The series branch B1 is connected between the input terminal IN and the output terminal OUT, one end of the parallel branch B2 is connected to the series branch B1, and the other end is connected to the ground terminal; the series branch B1 is provided with at least two series connected The series resonator R1 and the parallel branch B2 are provided with a parallel resonator R2.

In some embodiments, at least one (for example, also all) series resonators R1 in the above-mentioned series branch B1 may be set to adopt the resonators provided in any of the foregoing possible implementation manners of the present application.

In some embodiments, the parallel resonator R2 in the above at least one parallel branch B2 may be set to adopt the resonator provided in any of the foregoing possible implementation manners of the present application.

In some embodiments, the series resonator R1 in the series branch B1 and the parallel resonator R2 in the parallel branch B2 can be configured to use the resonators provided in any of the foregoing possible implementation manners of the present application.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited to this. should be covered within the scope of protection of this application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

A resonator, comprising: a piezoelectric substrate and an interdigital transducer arranged on the piezoelectric substrate; wherein the piezoelectric substrate includes a substrate, a reflective layer, a piezoelectric layer;

The interdigital transducer includes: a first bus bar, a second bus bar, and a plurality of interdigital electrodes juxtaposed between the first bus bar and the second bus bar; the plurality of interdigital electrodes The parallel arrangement direction of the finger electrodes is the first direction;

In the direction perpendicular to the first direction, the first bus bar and the second bus bar are distributed on both sides of the plurality of interdigitated electrodes; the plurality of interdigitated electrodes include first alternately arranged first an interdigitated electrode and a second interdigitated electrode; the first interdigitated electrode is connected to the first bus bar, and the second interdigitated electrode is connected to the second bus bar;

The resonator further includes: a first reflection groove disposed on the piezoelectric substrate;

The first reflection groove is located in a region between the first interdigital electrode and the second bus bar.
The resonator of claim 1, wherein

The resonator further includes: a second reflection groove disposed on the piezoelectric substrate;

The second reflection groove is located in a region between the second interdigital electrode and the first bus bar.
The resonator of claim 2, wherein

In the first direction, the size of the first reflection groove is larger than the width of the first interdigital electrode, and the size of the second reflection groove is larger than the width of the second interdigital electrode.
The resonator according to any one of claims 2-3, characterized in that,

The angle between the side wall of the first reflection groove on the side close to the first interdigital electrode and the vertical line of the piezoelectric substrate is 0-20°;

The included angle between the side wall of the second reflection groove on the side close to the second interdigital electrode and the vertical line of the piezoelectric substrate is 0-20°.
The resonator according to any one of claims 2-4, characterized in that,

The side wall of the first reflection groove on the side close to the first interdigital electrode is perpendicular to the piezoelectric substrate;

The sidewall of the second reflection groove on the side close to the second interdigital electrode is perpendicular to the piezoelectric substrate.
The resonator according to any one of claims 2-5, characterized in that,

The distance between the side wall of the first reflection groove on the side close to the first interdigital electrode and the first interdigital electrode is 0-2 μm;

The distance between the sidewall of the second reflection groove on the side close to the second interdigital electrode and the second interdigital electrode is 0˜2 μm.
The resonator according to any one of claims 2-6, characterized in that,

The first reflection groove and the second reflection groove are strip-shaped grooves, and the extending direction of the strip-shaped grooves is perpendicular to the interdigital electrodes.
The resonator according to any one of claims 2-7, wherein the first reflection groove and the second reflection groove are cross-shaped grooves;

The cross-shaped groove includes: a crossed first strip-shaped groove and a second strip-shaped groove; the extension direction of the first strip-shaped groove is perpendicular to the interdigital electrode, and the extension direction of the second strip-shaped groove is the same as that of the interdigitated electrode. The interdigitated electrodes are parallel.
The resonator according to any one of claims 2-8, characterized in that,

the first reflection groove penetrates the piezoelectric layer and the partial reflection layer;

The second reflection groove penetrates the piezoelectric layer and the partial reflection layer.
The resonator according to any one of claims 1-9, characterized in that,

The first reflection groove and the second reflection groove are filled with at least one of silicon dioxide and silicon nitride.
A filter, characterized by comprising the resonator according to any one of claims 1-10.
An electronic device, comprising a transceiver, a memory and a processor; wherein the transceiver includes the filter of claim 11 .
A method of making a resonator, comprising:

A reflective layer and a piezoelectric layer are sequentially formed on the substrate;

forming an interdigital transducer on the surface of the piezoelectric layer;

A protective film is formed on the surface of the interdigital transducer, and a hollow pattern is formed on the protective film; wherein, the position of the hollow pattern is located at the bus bar in the interdigital transducer opposite to the interdigital electrode Area;

At the position of the hollow pattern, the piezoelectric substrate is etched to form a reflection groove.