CN116505906A - Surface acoustic wave resonator - Google Patents

Abstract

The present application relates to a surface acoustic wave resonator, and relates to the field of surface acoustic wave devices. The surface acoustic wave resonator includes a supporting substrate, a piezoelectric film directly or indirectly arranged on the supporting substrate, and an interdigital transducer electrode arranged on the piezoelectric film; wherein, the occupation of the interdigital transducer electrode is The empty ratio is greater than or equal to 0.35 and less than or equal to 0.45. In this case, by adjusting the duty cycle of the interdigital transducer electrodes, high-order clutter in different frequency bands can be reduced or even eliminated, the stop-band suppression capability can be effectively improved, and a simpler, lower-cost production method is provided. Surface acoustic wave resonators based on piezoelectric thin films.

Description

Surface Acoustic Wave Resonator

technical field

The present application relates to the technical field of surface acoustic wave devices, in particular to a surface acoustic wave resonator.

Background technique

Surface acoustic wave resonators have been widely used in communication, medical, satellite, transportation and other fields. However, traditional surface acoustic wave resonators are limited by the material itself and cannot fully meet the performance requirements of high-end surface acoustic wave products. The surface acoustic wave resonator based on the composite bonding structure has attracted much attention due to its advantages of large bandwidth, low insertion loss, low temperature drift, high power and high out-of-band suppression, but the composite bonding structure will also cause many parasitic problems, such as high order clutter response, which will deteriorate the out-of-band rejection of the filter, and will also cause mode crosstalk between duplexers or radio frequency modules, greatly affecting the performance of communication devices.

Patent document CN110402539B discloses a surface acoustic wave resonator in which a silicon oxide film, a piezoelectric body made of lithium tantalate, and an interdigital transducer electrode are laminated on a supporting substrate made of silicon. The thickness of the piezoelectric body, the thickness and angle of the piezoelectric body, and the thickness of the interdigital transducer electrodes are used to suppress the response of the first high-order mode, the response of the second high-order mode, and the response of the third high-order mode. at least one.

Patent document CN113794458A discloses a surface acoustic wave resonator in which a groove array pattern is set in a composite film layer with a piezoelectric layer. By adjusting the depth and radial size of the pattern, high-order noise in different frequency bands can be reduced or even eliminated. Wave.

However, the scheme disclosed in the above-mentioned patent document CN110402539B is too complicated in design; the scheme disclosed in the above-mentioned patent document CN113794458A is too complicated in technology, which is not conducive to the production cost control of products; Surface acoustic wave resonators based on piezoelectric thin films.

Contents of the invention

The purpose of the present application is to provide a surface acoustic wave resonator to solve the above-mentioned problems of the existing surface acoustic wave resonator based on the piezoelectric thin film that the design is too complicated, the process is too complicated and the production cost is high.

In order to achieve the above object, the technical scheme adopted in this application is:

In a first aspect, the present application provides a surface acoustic wave resonator, comprising:

supporting substrate;

a piezoelectric film disposed directly or indirectly on the support substrate; and

interdigital transducer electrodes disposed on the piezoelectric film;

Wherein, the duty cycle of the IDT electrodes is greater than or equal to 0.35 and less than or equal to 0.45.

In a possible implementation manner, the piezoelectric film is directly disposed on the supporting substrate; or the piezoelectric film is directly disposed on a low-sonic material film, and the low-sonic material film is directly set on the supporting substrate; or the piezoelectric film is directly set on the low sound velocity material film, the low sound velocity material film is directly set on the capture material film, and the capture material film is directly set on on the support substrate.

In a possible implementation manner, the sound velocity of the bulk wave propagating in the low-sonic material film is lower than that of the bulk wave propagating in the piezoelectric film; the bulk wave propagating in the supporting substrate The speed of sound is higher than the speed of sound of the bulk wave propagating in the piezoelectric film.

In a possible implementation manner, the trapping material film is formed of one material or a combination of materials among amorphous silicon, polycrystalline silicon, amorphous germanium, or polycrystalline germanium.

In a possible implementation manner, the interdigital transducer electrodes include:

a plurality of first electrode fingers and a plurality of second electrode fingers interleaved with each other; and

a first bus bar and a second bus bar opposite to each other in the extending direction of the first electrode fingers and the second electrode fingers;

Wherein, the plurality of first electrode fingers and the plurality of second electrode fingers have respective first ends and second ends; the first ends of the plurality of first electrode fingers are connected to the first ends of the first electrodes A bus bar is directly connected, and the second ends of the plurality of first electrode fingers are spaced opposite to the second bus bar; the first ends of the plurality of second electrode fingers are connected to the second bus bar For direct connection, the second ends of the plurality of second electrode fingers are opposite to the first bus bar at intervals.

In a possible implementation manner, the interdigital transducer electrodes include:

m sub-layers formed by stacking multiple thin films of different metal materials, where m≥2.

In a possible implementation manner, the piezoelectric film is a lithium tantalate film or a lithium niobate film.

In a second aspect, the present application provides a filter device connected to an antenna, the filter device includes a series arm SAW resonator and a parallel arm SAW resonator, the series arm SAW resonator The surface acoustic wave resonator and at least one surface acoustic wave resonator in the parallel arm surface acoustic wave resonator is any one of the above mentioned surface acoustic wave resonators.

In a third aspect, the present application provides a multiplexer, including:

an antenna terminal connected to the antenna; and

A plurality of filter devices are commonly connected to the antenna terminal, and at least one of the filter devices is the above-mentioned filter device.

The beneficial effects brought by the technical solution provided by the application at least include:

By setting a supporting substrate, a piezoelectric film directly or indirectly arranged on the supporting substrate, and an interdigital transducer electrode arranged on the piezoelectric film, and the duty cycle of the interdigital transducer electrode is greater than or equal to 0.35 And less than or equal to 0.45. In this case, by adjusting the duty cycle of the interdigital transducer electrodes, high-order clutter in different frequency bands can be reduced or even eliminated, the stop-band suppression capability can be effectively improved, and a simpler, lower-cost production method is provided. Surface acoustic wave resonators based on piezoelectric thin films.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the present application, and do not constitute a limitation to the present application. In the attached picture:

FIG. 1 shows a top view of a surface acoustic wave resonator provided in Embodiment 1 of the present application;

Fig. 2 shows A-A' sectional schematic view of Fig. 1;

FIG. 3 shows the admittance-frequency curves of the surface acoustic wave resonator provided in Embodiment 1 of the present application at different duty ratios;

FIG. 4 shows a top view of a surface acoustic wave resonator provided in Embodiment 2 of the present application;

Fig. 5 shows the B-B' sectional schematic diagram of Fig. 4;

FIG. 6 shows the admittance-frequency curves of the surface acoustic wave resonator provided in Embodiment 2 of the present application at different duty ratios;

FIG. 7 shows a top view of a surface acoustic wave resonator provided in Embodiment 3 of the present application;

Fig. 8 shows the C-C ' sectional schematic diagram of Fig. 7;

FIG. 9 shows the admittance-frequency curves of the surface acoustic wave resonator provided in Embodiment 3 of the present application at different duty ratios;

Fig. 10 shows the impedance-frequency curves of different filters constructed by combining surface acoustic wave resonators with different duty ratios according to Embodiment 3 of the present application;

FIG. 11 shows a top view of a surface acoustic wave resonator provided in Embodiment 4 of the present application;

Fig. 12 shows the D-D' sectional schematic diagram of Fig. 11;

FIG. 13 shows the admittance-frequency curves of the surface acoustic wave resonator provided in Embodiment 4 of the present application at different duty ratios.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the 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 making creative efforts belong to the scope of protection of this application.

Among them, the same components are denoted by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the accompanying drawings of this application specification, and the word "bottom" and "top", "inner" and "outer" mean toward or away from a particular component, respectively. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of these features. In the description of this specification, "plurality" means two or more.

The application will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment one

Please refer to FIG. 1 to FIG. 2. FIG. 1 shows a top view of the surface acoustic wave resonator 100 provided by Embodiment 1 of the present application. FIG. 2 shows a schematic cross-sectional view of AA' in FIG. 1, defining a coordinate system parallel to The direction of the x-axis in is the electrode finger arrangement direction, the direction parallel to the y-axis in the coordinate system is defined as the extension direction of the electrode fingers, and the direction parallel to the z-axis in the coordinate system is defined as the height direction of the surface acoustic wave resonator 100 .

Specifically, the above SAW resonator 100 includes a support substrate 104 , a piezoelectric film 101 directly disposed on the support substrate 104 , and an interdigital transducer electrode 105 and a reflective grid electrode directly disposed on the piezoelectric film 101 .

In the embodiment of the present application, the supporting substrate 104 is implemented as a SiC (silicon carbide) substrate with a thickness of 500 μm, the piezoelectric film 101 is implemented as a 42° YX-lithium tantalate film with a thickness of 400 nm, and the interdigital transducer electrodes 105 and the reflection grid The electrodes are realized as multilayer composite electrodes mainly composed of aluminum electrodes.

Note that here, the sound velocity of the bulk wave propagating in the support substrate 104 is higher than the sound velocity of the bulk wave propagating in the piezoelectric film 101 .

Specifically, the IDT electrodes 105 include a plurality of first electrode fingers 107 and a plurality of second electrode fingers 108 interleaved with each other, and are opposite to each other in the extending direction of the first electrode fingers 107 and the second electrode fingers 108. The first bus bar 109 and the second bus bar 110, the plurality of first electrode fingers 107 and the plurality of second electrode fingers 108 all have respective first ends and second ends; the plurality of first electrode fingers 107 The first ends are directly connected to the first bus bar 109, the second ends of the plurality of first electrode fingers 107 are opposite to the second bus bar 110 at intervals; the first ends of the plurality of second electrode fingers 108 are connected to the second The bus bars 110 are directly connected, and the second ends of the plurality of second electrode fingers 108 are opposite to the first bus bars 109 at intervals.

Further, the reflective grid electrode includes a reflective grid electrode 1 106A and a reflective grid electrode 2 106B, and each reflective grid electrode includes a plurality of reflective grid electrode fingers and third busses that are opposite to each other in the extending direction of the multiple reflective grid electrode fingers. and the fourth bus bar, the plurality of reflective grid electrode fingers all have respective first ends and second end portions, the first ends of the reflective grid electrode fingers are directly connected to the third bus bar, and the first end portions of the reflective grid electrode fingers are directly connected to the third bus bar. The two ends are directly connected to the fourth bus bar.

In this case, define the width dimension of any electrode finger in the IDT electrode 105 along the x-axis direction as the electrode finger width a, and define any two adjacent electrodes in the IDT electrode 105 The distance dimension of the fingers along the x-axis direction is the electrode finger period p, which defines the duty ratio duty=a/p of any electrode finger in the IDT electrodes 105 .

In this embodiment, the reflective gate electrodes 106A and 106B both have 40 reflective gate electrodes.

In this embodiment, the electrode finger period p in the IDT electrode 105 is 1.0 μm; the total number of multiple first electrode fingers 107 and multiple second electrode fingers 108 is 200, and the multiple first electrode fingers 108 are 200. An electrode finger 107 and a plurality of second electrode fingers 108 both include a thinner Ti adhesion layer and a thicker Al host layer.

FIG. 3 shows the admittance-frequency curves of the surface acoustic wave resonator 100 provided in Embodiment 1 of the present application at different duty ratios, and the duty ratio of the interdigital transducer electrode 105 is 0.2 to 0.7. , it can be seen that the resonant frequency of the surface acoustic wave resonator 100 of this series is about 2380MHz, high-end clutter appears around 3200MHz, and high-end clutter appears at frequencies above 5700MHz.

It is worth noting that when the duty ratio of the IDT electrode 105 is in the range of 0.35 to 0.55, the high-end clutter of the surface acoustic wave resonator 100 above 5700 MHz is significantly suppressed. In one example, the duty cycle of the above-mentioned IDT electrodes 105 is set to be greater than or equal to 0.35 and less than or equal to 0.55. Preferably, the duty ratio of the above-mentioned IDT electrodes 105 is set to be greater than or equal to 0.35 and less than or equal to 0.45.

It can be understood that devices including such surface acoustic wave resonators, such as filters, modules or communication devices, can reduce or even eliminate high-order clutter in different frequency bands by adjusting the duty cycle of the IDT electrodes. , effectively improve the stop-band suppression ability.

Embodiment two

Please refer to FIGS. 4 to 5. FIG. 4 shows a top view of the surface acoustic wave resonator 200 provided in Embodiment 2 of the present application. FIG. 5 shows a schematic cross-sectional view of BB' in FIG. The direction of the x-axis in the coordinate system is the electrode finger arrangement direction, the direction parallel to the y-axis in the coordinate system is defined as the electrode finger extension direction, and the direction parallel to the z-axis in the coordinate system is defined as the height direction of the surface acoustic wave resonator 200 .

Specifically, the above-mentioned surface acoustic wave resonator 200 includes a support substrate 204, a low-sonic material film 202 directly disposed on the support substrate 204, a piezoelectric film 201 directly disposed on the low-sonic material film 202, and a The interdigital transducer electrodes 205 and reflective grid electrodes on the piezoelectric film 201.

In the embodiment of the present application, the supporting substrate 204 is realized as a Si (silicon) substrate with a thickness of 550 μm, the low sound velocity material film 202 is realized as a SiO ₂ (silicon dioxide) film with a thickness of 300 nm, and the piezoelectric film 201 is realized as a SiO 2 (silicon dioxide) film with a thickness of 600 nm. The 42° YX-lithium tantalate thin film, the interdigital transducer electrode 205 and the reflective grid electrode are implemented as a multilayer composite electrode mainly composed of aluminum electrodes.

It should be noted that, here, the sound velocity of the bulk wave propagating in the support substrate 204 is higher than that of the bulk wave propagating in the piezoelectric film 201, and the sound velocity of the bulk wave propagating in the low-sonic material film 202 is higher than that of the bulk wave propagating in the piezoelectric film 201. The sound velocity of the bulk wave propagating through the piezoelectric film 201 is low.

Specifically, the IDT electrodes 205 include a plurality of first electrode fingers 207 and a plurality of second electrode fingers 208 interleaved with each other, and are opposite to each other in the extending direction of the first electrode fingers 207 and the second electrode fingers 208. The first bus bar 209 and the second bus bar 210, the plurality of first electrode fingers 207 and the plurality of second electrode fingers 208 all have respective first ends and second ends; the plurality of first electrode fingers 207 The first end is directly connected to the first bus bar 209, the second end of the plurality of first electrode fingers 207 is spaced opposite to the second bus bar 210; the first end of the plurality of second electrode fingers 208 is connected to the second The bus bars 210 are directly connected, and the second ends of the plurality of second electrode fingers 208 are opposite to the first bus bars 209 at intervals.

Further, the reflective grid electrode includes a reflective grid electrode 1 206A and a reflective grid electrode 2 206B, and each reflective grid electrode includes a plurality of reflective grid electrode fingers and third busbars that are opposite to each other in the extending direction of the multiple reflective grid electrode fingers. and the fourth bus bar, the plurality of reflective grid electrode fingers all have respective first ends and second end portions, the first ends of the reflective grid electrode fingers are directly connected to the third bus bar, and the first end portions of the reflective grid electrode fingers are directly connected to the third bus bar. The two ends are directly connected to the fourth bus bar.

In this case, define the width dimension of any electrode finger in the IDT electrode 205 along the x-axis direction as the electrode finger width a, and define any two adjacent electrodes in the IDT electrode 205 The distance dimension of the fingers along the x-axis direction is the electrode finger period p, which defines the duty ratio duty=a/p of any electrode finger in the IDT electrodes 205 .

In this embodiment, the number of reflective grid electrode fingers of the first reflective grid electrode 206A and the second reflective grid electrode 206B is 20.

In this embodiment, the electrode finger period p in the IDT electrode 205 is 1.0 μm; the total number of multiple first electrode fingers 207 and multiple second electrode fingers 208 is 100, and the multiple first electrode fingers 208 are 100. An electrode finger 207 and a plurality of second electrode fingers 208 both include a thinner Ti adhesion layer and a thicker Al host layer.

Fig. 6 shows the admittance-frequency curves of the surface acoustic wave resonator 200 provided in Embodiment 2 of the present application at different duty ratios, and the duty ratio of the interdigital transducer electrode 205 is 0.2 to 0.7 , it can be seen that the resonant frequency of the surface acoustic wave resonator 200 of this series is about 2100MHz, high-end clutter appears around 2700MHz and 4000MHz, and high-end clutter appears at frequencies above 5600MHz.

It is worth noting that when the duty ratio of the IDT electrode 205 is in the range of 0.35 to 0.55, the high-end clutter of the surface acoustic wave resonator 200 above 5600 MHz is significantly suppressed. In one example, the duty cycle of the above-mentioned IDT electrode 205 is set to be greater than or equal to 0.35 and less than or equal to 0.55. Preferably, the duty cycle of the above-mentioned IDT electrode 205 is set to be greater than or equal to 0.35 and less than or equal to 0.45.

It can be understood that devices including such surface acoustic wave resonators, such as filters, modules or communication devices, can reduce or even eliminate high-order clutter in different frequency bands by adjusting the duty cycle of the IDT electrodes. , effectively improve the stop-band suppression ability.

Embodiment three

Please refer to FIG. 7 to FIG. 9. FIG. 7 shows a top view of the surface acoustic wave resonator 300 provided in Embodiment 3 of the present application. FIG. 8 shows a schematic cross-sectional view of CC' in FIG. The direction of the x-axis in is the electrode finger arrangement direction, the direction parallel to the y-axis in the coordinate system is defined as the extension direction of the electrode fingers, and the direction parallel to the z-axis in the coordinate system is defined as the height direction of the surface acoustic wave resonator 300 .

Specifically, the above-mentioned surface acoustic wave resonator 300 includes a supporting substrate 304, a trapping material film 303 directly disposed on the supporting substrate 304, a low-sonic material film 302 directly disposed on the trapping material film 303, a low-acoustic material film 302 directly disposed on the low-acoustic The piezoelectric film 301 on the fast material film 302 and the interdigital transducer electrodes 305 and reflective grid electrodes directly disposed on the piezoelectric film 301.

In the embodiment of the present application, the supporting substrate 304 is realized as a Si (silicon) substrate with a thickness of 500 μm, the capture material film 303 is realized as a polysilicon thin film with a thickness of 1000 nm, and the low sound velocity material film 302 is realized as a SiO ₂ (silicon dioxide) with a thickness of 300 nm. ) film, the piezoelectric film 301 is implemented as a 32° YX-lithium niobate film with a thickness of 300 nm, and the interdigital transducer electrodes 305 and reflective grid electrodes are implemented as multilayer composite electrodes mainly composed of aluminum electrodes.

It should be noted that, here, the sound velocity of the bulk wave propagating in the support substrate 304 is higher than that of the bulk wave propagating in the piezoelectric film 301, and the sound velocity of the bulk wave propagating in the low-sonic material film 302 is higher than that of the bulk wave propagating in the piezoelectric film 301. The sound velocity of the bulk wave propagating through the piezoelectric film 301 is low.

Specifically, the IDT electrodes 305 include a plurality of first electrode fingers 307 and a plurality of second electrode fingers 308 interleaved with each other, and are opposite to each other in the extending direction of the first electrode fingers 307 and the second electrode fingers 308. The first bus bar 309 and the second bus bar 310, the plurality of first electrode fingers 307 and the plurality of second electrode fingers 308 have respective first ends and second ends; the plurality of first electrode fingers 307 The first ends are directly connected to the first bus bar 309, the second ends of the plurality of first electrode fingers 307 are opposite to the second bus bar 310 at intervals; the first ends of the plurality of second electrode fingers 308 are connected to the second The bus bars 310 are directly connected, and the second ends of the plurality of second electrode fingers 308 are opposite to the first bus bars 309 at intervals.

Further, the reflective grid electrode includes a reflective grid electrode 1 306A and a reflective grid electrode 2 306B, and each reflective grid electrode includes a plurality of reflective grid electrode fingers and third busses that are opposite to each other in the extending direction of the multiple reflective grid electrode fingers. and the fourth bus bar, the plurality of reflective grid electrode fingers all have respective first ends and second end portions, the first ends of the reflective grid electrode fingers are directly connected to the third bus bar, and the first end portions of the reflective grid electrode fingers are directly connected to the third bus bar. The two ends are directly connected to the fourth bus bar.

In this case, define the width dimension of any electrode finger in the IDT electrode 305 along the x-axis direction as the electrode finger width a, and define any two adjacent electrodes in the IDT electrode 305 The distance dimension of the fingers along the x-axis direction is the electrode finger period p, which defines the duty ratio duty=a/p of any electrode finger in the IDT electrodes 305 .

In this embodiment, the number of reflective gate electrode fingers of the first reflective gate electrode 306A and the second reflective gate electrode 306B is 40.

In this embodiment, the electrode finger period p in the IDT electrode 305 is 1.0 μm; the total number of multiple first electrode fingers 307 and multiple second electrode fingers 308 is 160, and the multiple first electrode fingers 308 are 160. An electrode finger 307 and a plurality of second electrode fingers 308 both include a thinner Ti adhesion layer and a thicker Al host layer.

FIG. 9 shows the admittance-frequency curves of the surface acoustic wave resonator 300 provided in Embodiment 3 of the present application at different duty ratios, and the duty ratio of the interdigital transducer electrode 305 is 0.2 to 0.7. , it can be seen that the resonant frequency of the SAW resonator 300 of this series is about 2100MHz, there are small high-end clutter around 2300MHz and 2800MHz, and high-end clutter is present at frequencies above 5000MHz.

It is worth noting that when the duty ratio of the IDT electrodes 305 is in the range of 0.35 to 0.55, the high-end clutter of the surface acoustic wave resonator 300 above 5000 MHz is significantly suppressed. In one example, the duty ratio of the above-mentioned IDT electrodes 305 is set to be greater than or equal to 0.35 and less than or equal to 0.55. Preferably, the duty cycle of the above-mentioned IDT electrodes 305 is set to be greater than or equal to 0.35 and less than or equal to 0.45.

It can be understood that devices including such surface acoustic wave resonators, such as filters, modules or communication devices, can reduce or even eliminate high-order clutter in different frequency bands by adjusting the duty cycle of the IDT electrodes. , effectively improve the stop-band suppression ability.

FIG. 10 shows impedance-frequency curves of different filters constructed by combining surface acoustic wave resonators with different duty ratios according to Embodiment 3 of the present application.

As shown in Figure 10(a) is a filter based on the combination of surface acoustic wave resonators with a duty ratio of 0.2 in Figure 8 and Figure 9. It is easy to see that since the surface acoustic wave resonators are near 6600MHz and 7400MHz The existence of high-order clutter leads to the obvious deterioration of the out-of-band rejection of the filter built by it near the corresponding frequency band; as shown in Figure 10(c), it is based on the acoustic It is easy to see that the filter built by the surface wave resonator combination has obvious deterioration of out-of-band suppression near the corresponding frequency band due to the high-order clutter of the surface acoustic wave resonator near 5300MHz and 7300MHz; Figure 10(b) shows a filter based on the combination of surface acoustic wave resonators with a duty ratio of 0.4 in Figure 8 and Figure 9. It is easy to see that since the surface acoustic wave resonator is The frequency band suppresses the high-order clutter well, so that the filter built by it shows good out-of-band suppression performance in the corresponding frequency band.

Embodiment four

Please refer to FIG. 11 to FIG. 13. FIG. 11 shows a top view of the surface acoustic wave resonator 400 provided in Embodiment 4 of the present application. FIG. 12 shows a schematic cross-sectional view of D-D' in FIG. The direction of the x-axis in the coordinate system is the arrangement direction of the electrode fingers, the direction parallel to the y-axis in the coordinate system is defined as the extension direction of the electrode fingers, and the direction parallel to the z-axis in the coordinate system is defined as the height direction of the surface acoustic wave resonator 400 .

Specifically, the above-mentioned surface acoustic wave resonator 400 includes a support substrate 404, a trapping material film 403 directly disposed on the support substrate 404, a low-sonic material film 402 directly disposed on the trapping material film 403, a low-acoustic material film 402 directly disposed on the low-acoustic The piezoelectric film 401 on the fast material film 402 and the interdigital transducer electrodes 405 and reflective grid electrodes directly disposed on the piezoelectric film 401 .

In the embodiment of the present application, the supporting substrate 404 is realized as a Si (silicon) substrate with a thickness of 500 μm, the capture material film 403 is realized as a polysilicon thin film with a thickness of 1000 nm, and the low sound velocity material film 402 is realized as a SiO ₂ (silicon dioxide) with a thickness of 300 nm. ) film, the piezoelectric film 401 is implemented as a 32° YX-lithium niobate film with a thickness of 400 nm, and the interdigital transducer electrodes 405 and reflective grid electrodes are implemented as multilayer composite electrodes mainly composed of copper electrodes.

It should be noted that, here, the sound velocity of the bulk wave propagating in the support substrate 404 is higher than that of the bulk wave propagating in the piezoelectric film 401, and the sound velocity of the bulk wave propagating in the low-sonic material film 402 is higher than that of the bulk wave propagating in the piezoelectric film 401. The sound velocity of the bulk wave propagating through the piezoelectric film 401 is low.

Specifically, the IDT electrode 405 includes a plurality of first electrode fingers 407 and a plurality of second electrode fingers 408 interleaved with each other, and are opposite to each other in the extending direction of the first electrode fingers 407 and the second electrode fingers 408. The first bus bar 409 and the second bus bar 410, the plurality of first electrode fingers 407 and the plurality of second electrode fingers 408 all have respective first ends and second ends; the plurality of first electrode fingers 407 The first ends are directly connected to the first bus bar 409, the second ends of the plurality of first electrode fingers 407 are opposite to the second bus bar 410 at intervals; the first ends of the plurality of second electrode fingers 408 are connected to the second The bus bars 410 are directly connected, and the second ends of the plurality of second electrode fingers 408 are opposite to the first bus bars 409 at intervals.

Further, the reflective grid electrode includes a reflective grid electrode 1 406A and a reflective grid electrode 2 406B, and each reflective grid electrode includes a plurality of reflective grid electrode fingers and third busses that are opposite to each other in the extending direction of the multiple reflective grid electrode fingers. and the fourth bus bar, the plurality of reflective grid electrode fingers all have respective first ends and second end portions, the first ends of the reflective grid electrode fingers are directly connected to the third bus bar, and the first end portions of the reflective grid electrode fingers are directly connected to the third bus bar. The two ends are directly connected to the fourth bus bar.

In this case, define the width dimension of any electrode finger in the IDT electrode 405 along the x-axis direction as the electrode finger width a, and define any two adjacent electrodes in the IDT electrode 405 The distance dimension of the fingers along the x-axis direction is the electrode finger period p, which defines the duty ratio duty=a/p of any electrode finger in the IDT electrodes 405 .

In this embodiment, the number of reflective gate electrode fingers of the first reflective gate electrode 406A and the second reflective gate electrode 406B is 40.

In this embodiment, the electrode finger period p in the IDT electrode 405 is 1.0 μm; the total number of multiple first electrode fingers 407 and multiple second electrode fingers 408 is 200, and the multiple first electrode fingers 408 are 200. An electrode finger 407 and a plurality of second electrode fingers 408 both include a thinner Ti adhesion layer, a thicker Cu main body layer and a thinner Ti anti-oxidation layer.

Fig. 13 shows the admittance-frequency curves of the surface acoustic wave resonator 400 provided in Embodiment 4 of the present application at different duty ratios, and the duty ratio of the interdigital transducer electrode 405 is 0.2 to 0.7 , it can be seen that the resonant frequency of the SAW resonator 400 of this series is about 1700MHz, presents small high-end clutter around 2200MHz and 2800MHz, and presents high-end clutter at frequencies above 4100MHz.

It is worth noting that when the duty ratio of the IDT electrode 405 is in the range of 0.35 to 0.55, the high-end clutter of the SAW resonator 400 above 4100 MHz is significantly suppressed. In one example, the duty cycle of the above-mentioned IDT electrode 405 is set to be greater than or equal to 0.35 and less than or equal to 0.55. Preferably, the duty cycle of the above-mentioned IDT electrodes 405 is set to be greater than or equal to 0.35 and less than or equal to 0.45.

It can be understood that devices including such surface acoustic wave resonators, such as filters, modules or communication devices, can reduce or even eliminate high-order clutter in different frequency bands by adjusting the duty cycle of the IDT electrodes. , effectively improve the stop-band suppression ability.

In summary, for the piezoelectric film/supporting substrate stacked structure, piezoelectric film/low sound velocity material film/supporting substrate stacked structure, piezoelectric film/low sound velocity material film/capture material film/supporting substrate stacked structure For surface acoustic wave resonators, no matter whether the piezoelectric film is made of lithium tantalate film or lithium niobate film, whether the electrode of the interdigital transducer is made of copper electrode or aluminum electrode, when the duty ratio of the electrode of the interdigital transducer is set to 0.35 When it is within the range of 0.55, it can effectively suppress the high-end clutter of the resonator far away from the resonance frequency, which well proves the effectiveness of the structure of the present application, and the preparation process used by the structure is easy to realize and easy to be popularized and applied on a large scale.

In the embodiments disclosed in this application, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense. For example, "connection" can be a fixed connection or a detachable connection. Or integrally connected; "connected" can be directly connected or indirectly connected through an intermediary. Those skilled in the art can understand the specific meanings of the above terms in the embodiments disclosed in the present invention according to specific situations.

The above is only the preferred embodiment of the application, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the application, some improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of this application.

Claims (9)

1. A surface acoustic wave resonator, comprising:

a support substrate;

a piezoelectric film directly or indirectly disposed on the support substrate; and

interdigital transducer electrodes disposed on the piezoelectric film;

wherein the duty ratio of the interdigital transducer electrode is more than or equal to 0.35 and less than or equal to 0.45.

2. The surface acoustic wave resonator according to claim 1, characterized in that:

the piezoelectric film is directly disposed on the support substrate; or (b)

The piezoelectric film is directly disposed on a low acoustic speed material film that is directly disposed on the support substrate; or (b)

The piezoelectric film is disposed directly on a low acoustic speed material film disposed directly on a capture material film disposed directly on the support substrate.

3. The surface acoustic wave resonator according to claim 2, characterized in that:

the sound velocity of bulk waves propagating in the low sound velocity material film is lower than the sound velocity of bulk waves propagating in the piezoelectric film;

the sound velocity of the bulk wave propagating in the support substrate is higher than the sound velocity of the bulk wave propagating in the piezoelectric film.

4. The surface acoustic wave resonator according to claim 2, characterized in that:

the trapping material film is formed of one material or a combination of materials among amorphous silicon, polycrystalline silicon, amorphous germanium, or polycrystalline germanium.

5. The surface acoustic wave resonator according to claim 1, characterized in that the interdigital transducer electrode comprises:

a plurality of first electrode fingers and a plurality of second electrode fingers which are inserted in a staggered manner; and

a first bus bar and a second bus bar which are opposite to each other in the extending direction of the first electrode finger and the second electrode finger;

wherein the plurality of first electrode fingers and the plurality of second electrode fingers each have respective first and second ends; first ends of the plurality of first electrode fingers are directly connected with the first bus bar, and second ends of the plurality of first electrode fingers are opposite to the second bus bar at intervals; the first ends of the plurality of second electrode fingers are directly connected with the second bus bars, and the second ends of the plurality of second electrode fingers are opposite to the first bus bars at intervals.

6. The surface acoustic wave resonator according to claim 1, characterized in that the interdigital transducer electrode comprises:

and m sub-layers formed by laminating a plurality of films of different metal materials, wherein m is more than or equal to 2.

7. The surface acoustic wave resonator according to claim 1, characterized in that:

the piezoelectric film is a lithium tantalate film or a lithium niobate film.

8. A filter device connected to an antenna, the filter device comprising a series-arm surface acoustic wave resonator and a parallel-arm surface acoustic wave resonator, at least one of the series-arm surface acoustic wave resonator and the parallel-arm surface acoustic wave resonator being the surface acoustic wave resonator of any one of claims 1 to 7.

9. A multiplexer, comprising:

an antenna terminal connected to the antenna; and

a plurality of filter means commonly connected to said antenna terminals, at least one of said filter means being the filter means of claim 8.