CN117559951A

CN117559951A - Surface acoustic wave resonator and manufacturing method thereof

Info

Publication number: CN117559951A
Application number: CN202311682905.7A
Authority: CN
Inventors: 小野直大
Original assignee: Maxscend Microelectronics Co ltd
Current assignee: Maxscend Microelectronics Co ltd
Priority date: 2023-12-07
Filing date: 2023-12-07
Publication date: 2024-02-13

Abstract

The invention provides a surface acoustic wave resonator and a manufacturing method thereof, the resonator comprises a semiconductor layer and an electrode layer, an interdigital transducer positioned in the electrode layer comprises two interdigital electrodes which are oppositely arranged in a first direction, each interdigital electrode comprises a bus, a plurality of electrode fingers and virtual fingers which are connected with the bus and extend in the first direction, and the virtual fingers in the two interdigital electrodes are opposite to the electrode fingers and have gaps. According to the resonator, the propagation speed of the surface acoustic wave in the virtual finger area is reduced by the mass load effect brought by the mass load unit arranged in the virtual finger area and/or by increasing the width of the part of the electrode finger in the virtual finger area, so that the transverse energy leakage is reduced, the conductivity and admittance characteristics of the resonator in the frequency interval between the resonant frequency and the antiresonant frequency are improved, and the performance of the resonator is improved.

Description

Surface acoustic wave resonator and manufacturing method thereof

Technical Field

The invention belongs to the technical field of surface acoustic wave devices, and relates to a surface acoustic wave resonator and a manufacturing method thereof.

Background

The surface acoustic wave (Surface Acoustic Wave, SAW) technology plays an important role in the signal separation and filtering process of mobile communication, wherein the working principle of the surface acoustic wave resonator is as follows: the two interdigital transducers are arranged on the piezoelectric material layer at intervals, an electric signal is transmitted to one interdigital transducer, the input electric signal is converted into an acoustic wave signal based on the piezoelectric effect and is processed, and then the acoustic wave signal is converted into an electric signal through the other interdigital transducer and is output.

Referring to fig. 1 and 2, fig. 1 is a schematic top view of a basic SAW resonator, fig. 2 is a schematic longitudinal cross-sectional view of the SAW resonator at i-i' in fig. 1 and a schematic distribution of sound wave propagation velocity corresponding to the schematic longitudinal cross-sectional view, and an interdigital transducer in the SAW resonator is composed of two interdigital electrodes arranged in a staggered manner, each interdigital electrode includes a bus 101, an electrode finger 102 and a virtual finger 103, and a gap 104 is formed between the opposing electrode finger 102 and the virtual finger 103. Referring to fig. 3, a schematic diagram of the operation characteristics of the resonator shown in fig. 2 is shown, wherein curves a and B correspond to the admittance characteristics and the conductance characteristics of the resonator, respectively, the main mode of the resonator at the resonant frequency is a shear horizontal wave, the spurious frequencies occurring below the resonant frequency are due to the rayleigh wave, and the spurious frequencies occurring above the antiresonant frequency are due to the fast shear horizontal wave. In the piezoelectric material, 42 DEG YX-LiTaO ₃ Substrates (hereinafter referred to as 42 ° LT substrates) are widely used for manufacturing devices such as SAW filters and duplexers due to their characteristics, and there are problems in designing and manufacturing SAW resonators on 42 ° LT substrates, one of the problems is that a lateral energy leakage phenomenon occurs during operation of the SAW resonator, which results in a deterioration of resonator performance in a frequency interval between a resonant frequency and an anti-resonant frequency, and it has been found after research and analysis that the occurrence of the lateral energy leakage is caused by a speed change between different regions (such as bus bar, gap, dummy IDT and electrode finger IDT) on the resonator, more specifically, because the speed sequence of each region of the basic SAW resonator is: v_gap >V_busbar>=v_idt=v_dummy, which can create energy leakage.

At present, the solutions to the problem of lateral energy leakage include the following two methods: (1) As shown in fig. 4 and 5, the lateral energy leakage is reduced by reducing the distance between the oppositely disposed electrode fingers 102 and the dummy fingers 103 (i.e., the size of the gap 104) to reduce v_gap; (2) As shown in fig. 6 and 7, the two fingers are mutually shiftedTa is arranged above the energy device ₂ O ₅ Layer 105 (low speed dielectric) to cover the dummy finger area, bus bar area and gap area, using Ta ₂ O ₅ Layer 105 reduces the speed of the gap region to the bus bar region (relative to the speed of the electrode finger region) such that V/u _IDT >V_gap>V_busbar>=v_dummy to reduce lateral energy leakage. However, when the gap length is reduced, the effective width of the gap depends on the target resonant frequency of the resonator, and when the target resonant frequency is higher, the electrode fingers and the virtual fingers are narrower, the corresponding gap width is narrower, and the difficulty of the manufacturing process is remarkably increased; although Ta ₂ O ₅ The arrangement of the layers can effectively reduce the occurrence of the phenomenon of transverse energy leakage, but due to the limitation of material properties, the layer must have a certain thickness to achieve the effect of better reducing the propagation speed of sound waves in a specific area, the volume of the device is increased, and Ta ₂ O ₅ The layer manufacturing process is difficult and is also unfavorable for realizing mass production.

Therefore, how to provide a surface acoustic wave resonator and a manufacturing method thereof, so as to reduce transverse energy leakage without increasing manufacturing process difficulty, and improve working performance of the surface acoustic wave resonator, is an important technical problem to be solved by those skilled in the art.

It should be noted that the foregoing description of the background art is only for the purpose of facilitating a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background section of the present application.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a surface acoustic wave resonator and a method for manufacturing the same, which are used for solving the problem of increased process difficulty caused by the reduction of the lateral energy leakage during the operation of the surface acoustic wave resonator in the prior art.

To achieve the above and other related objects, the present invention provides a surface acoustic wave resonator comprising:

A semiconductor layer including a piezoelectric material layer;

the electrode layer is positioned on the piezoelectric material layer and comprises an interdigital transducer, the interdigital transducer comprises two interdigital electrodes which are oppositely arranged in a first direction, each interdigital electrode comprises a bus, a plurality of electrode fingers and virtual fingers, the electrode fingers are connected with the bus and extend in the first direction, the electrode fingers in the same interdigital electrode and the virtual fingers are alternately arranged at intervals in a second direction, the virtual fingers in the two interdigital electrodes are opposite to the electrode fingers and have gaps, and the second direction is perpendicular to the first direction;

the surface acoustic wave resonator comprises an electrode finger area, a gap area, a virtual finger area and a bus area in sequence from the center line of the surface acoustic wave resonator in the first direction to two sides, and when the surface acoustic wave propagates through the surface acoustic wave resonator, the propagation speed of the surface acoustic wave in the electrode finger area is between the propagation speed of the surface acoustic wave in the gap area and the propagation speed of the surface acoustic wave in the virtual finger area.

Optionally, the surface acoustic wave resonator further includes a mass loading layer, the mass loading layer is located above the electrode layer, the mass loading layer includes a plurality of first mass loading units and/or a plurality of second mass loading units, the first mass loading units are located above one end of the electrode finger connected with the bus, and the second mass loading units are located above the virtual finger.

Optionally, the saw resonator further comprises a passivation layer, the passivation layer being located between the electrode layer and the mass loading layer.

Optionally, when the mass-loading layer includes the second mass-loading unit, the second mass-loading unit also extends above the gap.

Optionally, the interdigital electrode further comprises a first strip extending along the second direction, and the first strip overlaps with the virtual finger and the electrode finger partially.

Optionally, in the same interdigital electrode, the width of the portion of the electrode finger located between the bus bar and the first strip is greater than or equal to the width of the portion of the electrode finger located between the first strip and the gap, and the width of the virtual finger is equal to the width of the portion of the electrode finger located between the bus bar and the first strip.

Optionally, the first mass-load unit also extends above the busbar and/or the second mass-load unit also extends above the busbar.

Optionally, the electrode layer further includes two reflection grids, the two reflection grids are respectively arranged at two sides of the interdigital transducer in the second direction, each reflection grid includes a plurality of reflection grids extending in the first direction, and the plurality of reflection grids are arranged at intervals in the second direction; the mass loading layer further comprises a plurality of third mass loading units located above both ends of the reflection grid in the first direction.

Optionally, each of the reflective gratings further includes two second strips extending in a second direction, the second strips partially overlapping the plurality of reflective gratings.

Optionally, the metallization rate of the interdigital electrode ranges from 0.3 to 0.7, and the pitch of the virtual finger is 100% -130% of the pitch of the electrode finger; when the distance between two adjacent electrode fingers in the same interdigital electrode is lambda, the aperture range of the interdigital transducer is 10 lambda-50 lambda, the length range of the gap is 0.025 lambda-2.0 lambda, the width range of the virtual finger is 0.025 lambda-2.0 lambda, and the thickness range of the electrode finger is 0.025 lambda-0.15 lambda.

Optionally, the material of the mass loading layer comprises at least one of Al, ti, cu, pt, mo, W, cr and Au, and the thickness of the mass loading layer ranges from 0.0025λ to 0.125λ.

Optionally, the width of the portion of the electrode finger located in the virtual finger region is greater than the width of the portion of the electrode finger located in the gap region and the width of the portion of the electrode finger located in the electrode finger region.

The invention also provides a manufacturing method of the surface acoustic wave resonator, which comprises the following steps:

Providing a semiconductor layer comprising a layer of piezoelectric material;

forming an electrode layer on the piezoelectric material layer, wherein the electrode layer comprises an interdigital transducer, the interdigital transducer comprises two interdigital electrodes which are oppositely arranged in a first direction, each interdigital electrode comprises a bus, a plurality of electrode fingers connected with the bus and extending in the first direction and virtual fingers, the electrode fingers in the same interdigital electrode and the virtual fingers are alternately arranged at intervals in a second direction, the virtual fingers in the two interdigital electrodes are opposite to the electrode fingers and have gaps, and the second direction is perpendicular to the first direction;

As described above, according to the surface acoustic wave resonator and the manufacturing method thereof, the first mass load unit and the second mass load unit are respectively arranged above the parts of the virtual finger and the electrode finger, which are positioned in the virtual finger area, so that the propagation speed of the surface acoustic wave in the virtual finger area is reduced by utilizing the mass load effect, and/or the propagation speed of the surface acoustic wave in the virtual finger area is reduced by increasing the width of the part of the electrode finger, which is positioned in the virtual finger area, so that the propagation speed of the surface acoustic wave in the virtual finger area is lower than the propagation speed of the surface acoustic wave in the electrode finger area, and the transverse energy leakage is reduced to a certain extent, thereby improving the conductivity characteristic and the admittance characteristic of the frequency interval between the resonant frequency and the antiresonant frequency of the surface acoustic wave resonator, and effectively improving the working performance of the surface acoustic wave resonator.

Drawings

Fig. 1 shows a schematic top view of a basic SAW resonator.

FIG. 2 shows a schematic view of the structure along the longitudinal section at I-I' in FIG. 1 and a schematic view of the corresponding acoustic wave propagation velocity profile.

Fig. 3 shows a schematic diagram of the operating characteristics of the resonator shown in fig. 2.

Fig. 4 shows a schematic top view of a resonator with a narrow gap.

Fig. 5 is a schematic longitudinal section of the structure shown in fig. 4 and a schematic corresponding acoustic wave propagation velocity distribution.

FIG. 6 shows a film with Ta ₂ O ₅ Schematic top view of the resonator of the layer.

Fig. 7 is a schematic longitudinal section of the structure shown in fig. 6 and a schematic corresponding acoustic wave propagation velocity distribution.

Fig. 8 is a schematic top view of a saw resonator according to a first embodiment of the invention.

FIG. 9 is a schematic view of a longitudinal section along II-II' in FIG. 8 and a corresponding schematic view of the propagation velocity profile of sound waves.

Fig. 10 is an enlarged schematic view showing a partial structure of the electrode layer of fig. 8.

Fig. 11 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 8.

Fig. 12 is a schematic view showing a longitudinal sectional structure of a surface acoustic wave resonator according to the first embodiment of the present invention having a POI substrate.

Fig. 13 is a schematic view showing a longitudinal cross-sectional structure of a saw resonator according to the first embodiment of the invention having a temperature compensation layer.

Fig. 14 is a schematic top view of a saw resonator according to a second embodiment of the present invention.

Fig. 15 is a schematic longitudinal cross-sectional view of the structure of fig. 14 and a schematic propagation velocity of sound waves in different regions.

Fig. 16 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 14.

Fig. 17 is a schematic top view of a surface acoustic wave resonator according to a third embodiment of the present invention.

Fig. 18 is a schematic longitudinal cross-sectional view of the structure of fig. 17 and schematic propagation velocity of sound waves in different regions.

Fig. 19 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 17.

Fig. 20 is a schematic view showing a longitudinal sectional structure of a surface acoustic wave resonator according to the third embodiment of the present invention having a POI substrate.

Fig. 21 is a schematic longitudinal sectional view of the surface acoustic wave resonator according to the third embodiment of the present invention having a temperature compensation layer.

Fig. 22 is a schematic diagram showing a second top view structure of a saw resonator according to a third embodiment of the present invention.

FIG. 23 is a schematic longitudinal cross-sectional view of the structure of FIG. 22 and schematic propagation velocity of sound waves in different regions.

Fig. 24 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 22.

Fig. 25 is a schematic top view of a surface acoustic wave resonator according to a first embodiment of the present invention.

FIG. 26 is a schematic longitudinal cross-sectional view of the structure of FIG. 25 showing the propagation velocity of sound waves in different regions.

Fig. 27 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 25.

Fig. 28 is a schematic top view of a surface acoustic wave resonator according to a second embodiment of the present invention.

Fig. 29 is a schematic longitudinal cross-sectional view of the structure of fig. 28 and schematic propagation velocity of sound waves in different regions.

Fig. 30 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 28.

Fig. 31 is a schematic top view of a surface acoustic wave resonator according to a fifth embodiment of the present invention.

Fig. 32 is a schematic top view of the electrode layer in the structure of fig. 31.

Fig. 33 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 31.

Fig. 34 is a schematic top view of the structure of fig. 31 with a temperature compensation layer.

Fig. 35 is a schematic top view of a third embodiment of a saw resonator according to the present invention.

Fig. 36 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 35.

Fig. 37 is a schematic top view of a surface acoustic wave resonator according to a first embodiment of the present invention.

Fig. 38 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 37.

Fig. 39 is a schematic diagram showing a second top view structure of a saw resonator according to a sixth embodiment of the present invention.

Fig. 40 is a diagram showing the effect of the change in admittance (susceptance) with frequency of the surface acoustic wave resonator having the structure shown in fig. 38.

Fig. 41 is a schematic top view of a third embodiment of a saw resonator according to the present invention.

Fig. 42 is a schematic longitudinal cross-sectional view of the structure of fig. 41 and a schematic corresponding acoustic wave propagation velocity distribution.

Description of the reference numerals

101. Bus bar

102. Electrode finger

103. Virtual finger

104. Gap of

105 Ta ₂ O ₅ Layer(s)

1. Semiconductor layer

11. Piezoelectric material layer

12. Substrate layer

2. Electrode layer

21. Interdigital transducer

211. Bus bar

212. Electrode finger

213. Virtual finger

214. Gap of

215. First strip-shaped piece

22. Reflective grating

221. Reflection bus

222. Reflection grid

223. Second strip-shaped piece

3. Mass loading layer

31. First mass-loading unit

32. Second mass-loading unit

33. Third mass-loading unit

4. Temperature compensation layer

5. Passivation layer

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.

Please refer to fig. 8-42. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.

Example 1

The embodiment provides a saw resonator, please refer to fig. 8 and 9, wherein fig. 8 is a schematic top view of the saw resonator, fig. 9 is a schematic longitudinal cross-sectional view along a plane ii-ii' in fig. 8 (hereinafter, referred to simply as a "schematic longitudinal cross-sectional view") and a schematic propagation velocity of an acoustic wave in different regions, and the saw resonator includes a semiconductor layer 1 and an electrode layer 2.

Specifically, the semiconductor layer 1 includes a piezoelectric material layer 11; the electrode layer 2 is located on the piezoelectric material layer 11, the electrode layer 2 includes an interdigital transducer 21, the interdigital transducer 21 includes two interdigital electrodes disposed opposite to each other in a first direction (X direction shown in fig. 8), each of the interdigital electrodes includes a bus bar 211, a plurality of electrode fingers 212 connected to the bus bar 211 and extending in the first direction, and a plurality of virtual fingers 213, the plurality of electrode fingers 212 and the plurality of virtual fingers 213 in the same interdigital electrode are alternately arranged at intervals in a second direction (Y direction shown in fig. 8), the virtual fingers 213 in the two interdigital electrodes are opposed to the electrode fingers 212 with gaps 214 (here, "with gaps" means that there are gaps between the oppositely disposed virtual fingers and the electrode fingers), and the second direction is perpendicular to the first direction; the SAW resonator comprises electrode finger regions (IDT), gap regions (gap), virtual finger regions (dummy IDT) and Bus bar regions (Bus bar) on both sides of the center line of the SAW resonator in the first direction, wherein in the first direction, the Bus bar region refers to the region where the Bus bar is located, the virtual finger region refers to the region where the virtual finger is located (part of the electrode finger is arranged in the virtual finger region besides the virtual finger), and the gap region refers to the region where the gap is located (part of the electrode finger is arranged in the gap region) A portion of the electrode fingers is provided outside the gap), and the electrode finger region refers to a region where the electrode fingers overlap in the second direction. When a surface acoustic wave propagates through the surface acoustic wave resonator, the propagation velocity of the surface acoustic wave in the electrode finger region is between the propagation velocity of the surface acoustic wave in the gap region and the propagation velocity of the surface acoustic wave in the virtual finger region, and the propagation velocity of the surface acoustic wave in the bus region is less than or equal to the propagation velocity of the surface acoustic wave in the electrode finger region (i.e., vgap > V _IDT ≥V _Bus-bar ＞V _dummy _IDT ). In this embodiment, the propagation velocity of the surface acoustic wave in the bus bar region is equal to the propagation velocity thereof in the electrode finger region (i.e., vgap > V _IDT ＝V _Bus-bar ＞V _dummy _IDT )。

As an example, the piezoelectric material layer 11 is 42 ° YX-LiTaO ₃ Or other suitable material.

As an example, the saw resonator further comprises a mass-loaded layer 3, the mass-loaded layer 3 being located above the electrode layer 2, the mass-loaded layer 3 comprising a plurality of first mass-loaded cells 31 and/or a plurality of second mass-loaded cells 32, the first mass-loaded cells 31 being located above the end of the electrode finger 212 connected to the busbar 211, the second mass-loaded cells 32 being located above the virtual finger 213. It should be noted that, in this embodiment, the mass loading layer includes both the first mass loading unit and the second mass loading unit, and in other embodiments, the mass loading unit may include only one of the first mass loading unit and the second mass loading unit, and is selected based on actual needs.

As an example, the width of the first mass-loading unit 31 is smaller than or equal to the width of the electrode finger 212, the width of the second mass-loading unit 32 is smaller than or equal to the width of the virtual finger 213, and the width of the first mass-loading unit 31 is equal to or different from the width of the second mass-loading unit 32. The width of the dummy finger 213 in this embodiment is equal to the width of the electrode finger 212, and on the basis of this, the width of the first mass-loading unit 31 is also equal to the width of the electrode finger 212. Furthermore, the length of the second mass-loading unit 32 is preferably consistent with the length of the virtual finger 213 (i.e., the second mass-loading unit 32 completely covers over the virtual finger 213), and the length of the first mass-loading unit 31 is preferably consistent with the length of the second mass-loading unit 32.

As an example, the electrode layer 2 further includes two reflection grids 22, the two reflection grids 22 are disposed on both sides of the interdigital transducer 21 in the second direction, each reflection grid 22 includes a plurality of reflection grids 222 extending in the first direction and the plurality of reflection grids 222 are arranged at intervals in the second direction, and furthermore, each reflection grid 22 further includes two reflection grid bus bars 221, the plurality of reflection grids 222 are arranged between the two reflection grid bus bars 221 at intervals, and the reflection grids 22 are capable of reflecting stray waves of acoustic surface waves outside the main mode propagation direction back, thereby reducing energy loss. The number of electrode fingers in this embodiment is 150, and the number of reflective strips is 30.

Further, in the case that the electrode layer 2 further includes two reflective grids 22, the mass-loading layer 3 further includes a plurality of third mass-loading units 33, the third mass-loading units 33 are located above both ends of the reflective grid bars 222 in the first direction, and the specifications of the third mass-loading units 33 are preferably consistent with those of the first mass-loading units 31 and the second mass-loading units 32 (i.e., parameters such as length, width, and thickness are consistent).

As an example, referring to fig. 10, which is an enlarged schematic view of a partial structure of the electrode layer in fig. 8, when a distance between two adjacent electrode fingers 212 in the same interdigital electrode (shown in fig. 10 a) is λ, an aperture of the interdigital transducer 21 (a size of a portion of the electrode fingers 212 of the two interdigital electrodes overlapping each other in the second direction, as shown in fig. 10 b) ranges from 10λ to 50λ, including, but not limited to 10λ, 20λ, 30λ, 40λ, and 50λ; the gap 214 has a length (shown in fig. 10 c) in the range of 0.025 λ to 2.0 λ, including but not limited to 0.025 λ, 0.5 λ, 1.0 λ, 1.5 λ, and 2.0 λ; the width of the dummy finger 213 (shown as d in fig. 10) ranges from 0.025 λ to 2.0 λ, including but not limited to 0.025 λ 0.1 λ, 0.5 λ, 1.0 λ, 1.5 λ, and 2.0 λ; the thickness of the electrode finger 212 (shown as g in fig. 9) ranges from 0.025 lambda to 0.15 lambda, including but not limited to 0.025 lambda, 0.08 lambda, 0.10 lambda, and 0.15 lambda. Taking lambda as 4 μm as an example, the aperture of the interdigital ring device in the embodiment is 60 μm, the gap length is 2 μm, the virtual finger length is 6 μm, and the electrode finger thickness is 374 nm.

As an example, the pitch of the dummy finger 213 (the distance between two adjacent dummy fingers, e in fig. 10) is 100% -130% of the pitch of the electrode finger 212 (the distance between two adjacent electrode fingers, f in fig. 10), the metallization rate of the interdigital transducer ranges from 0.3 to 0.7 ("metallization rate" refers to the ratio between the width of the electrode finger 212 and the pitch of the electrode finger 212), including but not limited to 0.3, 0.4, 0.5, 0.6 and 0.7, when the metallization rate is 0.5, meaning that the distance between two adjacent electrode fingers is equal to the width of the electrode finger, when the metallization rate is greater than 0.5, meaning that the distance between two adjacent electrode fingers is smaller than the width of the electrode finger, when the metallization rate is less than 0.5, meaning that the distance between two adjacent electrode fingers is greater than the width of the electrode finger, the "metallization rate" corresponds to the distribution area of the electrode in the electrode finger region, and in this embodiment, when the metallization rate is 0.5, the metallization rate of the interdigital transducer is 0.5, can be adjusted based on the actual values required to ensure the performance of the aforementioned range.

As an example, the material of the mass loading layer 3 includes at least one of Al, ti, cu, pt, mo, W, cr and Au, the thickness of the mass loading layer 3 (as shown by h in fig. 9) ranges from 0.0025λ to 0.125λ, including but not limited to 0.0025λ, 0.005 λ, 0.01λ, 0.05λ, 0.1λ and 0.125λ, the material of the mass loading layer 3 in this embodiment is Al/Ti, and the thickness of the mass loading layer 3 is 115nm.

Specifically, the surface acoustic wave resonator of the embodiment adds a mass loading layer on the basis of a general surface acoustic wave resonator, and each mass loading unit in the mass loading layer is distributed above the virtual finger and the electrode finger, and the propagation speed of sound waves in the corresponding area is reduced due to the mass loading effect brought by the area with the mass loading unit, so that transverse energy leakage is reduced. Referring to fig. 11, an effect diagram of the change of admittance (susceptance) of the saw resonator with the structure shown in fig. 8 with frequency is shown, wherein the curve A1 and the curve A2 correspond to the admittance and the conductance change curve of the reference model resonator respectively, the curve A2 and the curve B2 correspond to the admittance and the conductance change curve of the resonator of the present embodiment respectively, the comparison curve A2 and the curve A1 and the comparison curve B2 and the curve B1 can be known, the conductance characteristic and the admittance characteristic of the saw resonator in the frequency region between the resonant frequency (f 1 in fig. 11) and the anti-resonant frequency (f 2 in fig. 11) are improved (the conductance characteristic improving effect is particularly obvious), and the conductance of the saw resonator of the present embodiment is reduced by 2dB to 4dB in the frequency region compared with the conductance of the reference model at the same frequency, and the present time, the frequency difference 1dB can bring a significant competitive advantage with the continuous optimization of the resonator structure. As can be seen from a combination of fig. 10 and 11, the technical effect presented in fig. 11 is that the arrangement of the mass-loaded units reduces the propagation velocity of the surface acoustic wave in the virtual IDT region so that the velocity in the region is lower than that in the IDT region, thereby reducing the lateral energy spread. In addition, the thickness of the mass loading layer can realize better mass loading effect under the condition of relatively thinner, the whole volume of the resonator can not be obviously changed, and the mass loading layer can be manufactured by adopting a conventional semiconductor metal film manufacturing method, so that the manufacturing process difficulty of the resonator can not be additionally increased.

As an example, the semiconductor layer 1 further includes a substrate layer 12 (not shown in fig. 8, please refer to fig. 12 in combination) under the piezoelectric material layer 11, where the substrate layer 12 is a Si substrate or a Si substrate having an oxide layer on a surface (i.e., a POI substrate is formed with the piezoelectric material layer). In this embodiment, the substrate layer 12 is a Si substrate, and the SAW resonator is a conventional SAW. Referring to fig. 12, a schematic view of a longitudinal cross-sectional structure of a SAW resonator with a POI substrate is shown, and in one embodiment, the substrate layer 12 is a Si substrate with an oxide layer on a surface, where the SAW resonator is a POI-SAW.

As an example, referring to fig. 13, a schematic view of a longitudinal cross-section structure of a SAW resonator with a temperature compensation layer is shown, the SAW resonator further includes a temperature compensation layer 4, the temperature compensation layer 4 covers the electrode layer 2 and the mass load layer 3, that is, in the case of having the temperature compensation layer 4, the SAW resonator is TC-SAW, and the temperature compensation layer 4 is configured to reduce a temperature coefficient of a resonant frequency of the resonator (approaching zero) to provide temperature compensation, so as to avoid a drift of a signal due to temperature fluctuation, and ensure stability of operating performance of the resonator. The material of the temperature compensation layer 4 includes silicon dioxide or other suitable materials.

According to the surface acoustic wave resonator, the first mass load unit and the second mass load unit are respectively arranged above the parts of the virtual finger and the electrode finger, which are located in the virtual finger area, so that the propagation speed of the surface acoustic wave in the virtual finger area is reduced by utilizing the mass load effect, the propagation speed of the surface acoustic wave in the virtual finger area is lower than that of the surface acoustic wave in the electrode finger area, so that transverse energy leakage is reduced to a certain extent, the conductivity characteristic and admittance characteristic of the surface acoustic wave resonator in a frequency interval between the resonant frequency and the antiresonant frequency are improved, the working performance of the surface acoustic wave resonator is effectively improved, and in addition, the temperature compensation layer is further arranged or the POI substrate is selected according to actual requirements, so that the device performance is further improved.

Example two

The present embodiment provides a surface acoustic wave resonator, which is different from the surface acoustic wave resonator in the first embodiment in that: in this embodiment, the first mass-loading unit and the second mass-loading unit extend above the bus bar, and in the first embodiment, the first mass-loading unit only covers above the virtual finger and the second mass-loading unit only covers above the end of the electrode finger connected with the bus bar, and does not extend onto the bus bar.

Specifically, referring to fig. 14 and 15, fig. 14 shows a schematic top view of the saw resonator, fig. 15 shows a schematic longitudinal section of the structure shown in fig. 14 and a schematic propagation speed of a sound wave in different regions, the saw resonator includes a semiconductor layer 1 and an electrode layer 2, the saw resonator is sequentially provided with electrode finger regions, a gap region, a virtual finger region and a bus region from a center line of the saw resonator in a first direction, when a saw propagates through the saw resonator, the propagation speed of the saw in the electrode finger region is between the propagation speed of the saw in the gap region and the propagation speed of the saw in the virtual finger region, and the propagation speed of the saw in the bus region is less than or equal to the propagation speed of the saw in the electrode finger region (i.e., vgap > V) _IDT ≥V _Bus-bar ＞V _dummy _IDT ). In this embodiment, since the first mass-loading unit 31 and the second mass-loading unit 32 extend from the virtual finger region to the bus region, the propagation speed of the surface acoustic wave in the bus region is also smaller than that in the electrode finger region (i.e. Vgap > V) _IDT ＞V _Bus-bar ＝V _dummy _IDT ) Compared to structures that do not extend to the bus bar region, lateral energy that would otherwise leak through the bus bar region can be further reduced.

As an example, the saw resonator further comprises a mass-loading layer 3, the mass-loading layer 3 being located above the electrode layer 2, the mass-loading layer 3 comprising a plurality of first mass-loading units 31 and/or a plurality of second mass-loading units 32, the first mass-loading units 31 being located above the end of the electrode finger 212 connected to the busbar 211, the second mass-loading units 32 being located above the virtual finger 213.

Further, as shown in fig. 14 and 15, the first mass-loading unit 31 further extends above the bus bar 211 and/or the second mass-loading unit 32 further extends above the bus bar 211, and preferably, the mass-loading unit extending above the bus bar 211 completely covers the area of the bus bar 211 in the extending direction of the mass-loading unit (i.e. extends to the edge of the bus bar 211), so as to achieve a better mass-loading effect. Specifically, referring to fig. 16, an effect diagram of the admittance (susceptance) of the saw resonator having the structure shown in fig. 14 along with the frequency is shown, wherein the curve A3 and the curve B3 are the admittance and the conductance change curves corresponding to the resonator of the embodiment, respectively, and compared with the curve A1 and the curve B1, respectively, the conductance characteristics and the admittance characteristics of the saw resonator having the structure shown in fig. 14 in the region between the resonant frequency and the antiresonant frequency are significantly improved.

According to the surface acoustic wave resonator, the first mass load unit and the second mass load unit are respectively arranged above the parts of the virtual finger and the electrode finger, which are located in the virtual finger area, and the mass load units extend to the bus area, so that the propagation speeds of the surface acoustic wave in the virtual finger area and the bus area are reduced by using the mass load effect brought by the mass load units, the propagation speeds of the surface acoustic wave in the two areas are lower than those of the surface acoustic wave in the electrode finger area, the transverse energy leakage of the surface acoustic wave from the virtual finger area and the bus area when the surface acoustic wave propagates in the interdigital ring energy device can be reduced, the conductivity characteristic and the admittance characteristic of the surface acoustic wave resonator in a frequency interval between the resonant frequency and the antiresonant frequency are improved, and the quality factor of the surface acoustic wave resonator is effectively improved.

Example III

The present embodiment provides a surface acoustic wave resonator, which is different from the surface acoustic wave resonator in the first embodiment in that: the saw resonator in this embodiment further includes a passivation layer while the saw resonator in the first embodiment does not include a passivation layer.

Specifically, referring to fig. 17 and 18, fig. 17 is a schematic top view of the saw resonator, fig. 18 is a schematic longitudinal cross-sectional view of the structure shown in fig. 17 and a schematic propagation velocity of an acoustic wave in different regions, and the saw resonator includes a semiconductor layer 1, an electrode layer 2 and a mass loading layer 3.

As an example, as shown in fig. 17 and 18, the saw resonator further includes a passivation layer 5, where the passivation layer 5 is located between the electrode layer 2 and the mass loading layer 3, that is, after the electrode layer 2 is manufactured, the passivation layer 5 is formed on the electrode layer 2 so that the passivation layer 5 completely fills the gap 214 and is higher than the electrode layer 2 by a preset value, and then the mass loading layer 3 is formed above the passivation layer 5, where the preset value is 1/5 of the thickness of the mass loading layer 3, and the passivation layer 5 can play a role of overall lateral energy leakage to further improve the working performance of the resonator.

By way of example, the material of the passivation layer 5 may comprise silicon nitride or other suitable material, which may not add additional cost to the fabrication while enhancing resonator performance.

Specifically, referring to fig. 19, an effect diagram of the admittance (susceptance) of the saw resonator with the structure shown in fig. 17 along with the frequency is shown, wherein the curve A4 and the curve B4 are the admittance and the conductance change curves corresponding to the resonator of the embodiment, respectively, and compared with the curve A1 and the curve B1, on one hand, the conductance characteristics and the admittance characteristics of the saw resonator with the structure shown in fig. 17 at each frequency are improved, especially the conductance characteristics and the admittance characteristics in the area between the resonant frequency f1 and the antiresonant frequency f2 are obviously improved (f 1 and f2 are shown in fig. 11), on the other hand, the antiresonant frequency f2 of the resonator is slightly reduced compared with the reference model due to the fact that the coupling capacitance is generated on the passivation layer, so that the mechanical coupling coefficient k2 of the resonator is also reduced (k2= (f 2/f 1) 2-1×100%), and the energy loss in the resonator in the working process can be further reduced, thereby improving the working performance thereof.

Similarly, the semiconductor layer 1 further includes a substrate layer 12 (not shown in fig. 17, please refer to fig. 20 in combination) under the piezoelectric material layer 11, where the substrate layer 12 is a Si substrate or a Si substrate having an oxide layer on a surface (i.e. forms a POI substrate with the piezoelectric material layer 11). When the substrate layer 12 is a Si substrate, the SAW resonator is a conventional SAW. When the substrate layer 12 is a POI substrate (as shown in fig. 20), the SAW resonator is a POI-SAW.

As an example, referring to fig. 21 in combination, the SAW resonator further includes a temperature compensation layer 4, where the temperature compensation layer 4 covers the electrode layer 2 and the mass loading layer 3, i.e. the SAW resonator is TC-SAW with the temperature compensation layer 4.

As an example, in the case of the passivation layer 5 and the mass loading layer 3 including the second mass loading unit 32, the second mass loading unit 32 also extends above the gap 214, and preferably, the second mass loading unit 32 completely covers the upper region of the gap 214, please refer to fig. 22 and 23, fig. 22 is a schematic top view of the structure in which the second mass loading unit is located above the virtual finger and the gap, fig. 23 is a schematic longitudinal cross-sectional view of the structure shown in fig. 22 and a schematic propagation speed of the sound wave in different regions, and at the same time, the first mass loading unit 31 also extends into the gap region to be flush with the second mass loading unit 32 (in the case of the third mass loading unit 33, the third loading unit is also flush with the second mass loading unit 32). Referring to fig. 24, an effect of the change of admittance (susceptance) with frequency of the saw resonator with the structure shown in fig. 22 is shown, wherein a curve A5 and a curve B5 are respectively corresponding to the admittance and the conductance change curve of the resonator, the conductance characteristics and admittance characteristics of the saw resonator with the structure shown in fig. 22 are improved at each frequency compared with the curve A1 and the curve B1, respectively, and the performance improvement effect of the resonator is more remarkable compared with the structure not extending to the gap 214 (i.e. compared with fig. 19 and fig. 24), the conductance of the resonator is reduced by 2dB to 6dB compared with the conductance of the reference model at the same frequency and within a part of the frequency range.

The surface acoustic wave resonator of the embodiment can reduce the leakage of transverse energy from the virtual finger area, thereby improving the conductivity characteristic and admittance characteristic of the surface acoustic wave resonator in the frequency interval between the resonant frequency and the antiresonant frequency. In addition, due to the arrangement of the passivation layer, the mechanical coupling coefficient k2 of the surface acoustic wave resonator is reduced, and the working performance of the surface acoustic wave resonator is effectively improved.

Example IV

The difference between the surface acoustic wave resonator according to the third embodiment and the surface acoustic wave resonator according to the third embodiment is that: in this embodiment, the first mass load unit and the second mass load unit extend above the bus bar, while in the third embodiment, the first mass load unit only covers above the virtual finger, the second mass load unit only covers above the end of the electrode finger connected with the bus bar, and none of the first mass load unit and the second mass load unit extends above the bus bar.

Specifically, referring to fig. 25 and 26, fig. 25 is a schematic top view of the saw resonator with a passivation layer, fig. 26 is a schematic longitudinal section of the saw resonator with a passivation layer and a schematic propagation speed of sound waves in different regions, the saw resonator includes a semiconductor layer 1, an electrode layer 2, and a mass loading layer 3, wherein the mass loading layer 3 is located above the electrode layer 2, the mass loading layer 3 includes a plurality of first mass loading units 31 and a plurality of second mass loading units 32, the first mass loading units 31 are located above an end of the electrode finger 212 connected to the bus 211, and the second mass loading units 32 are located above the virtual finger 213.

As an example, as shown in fig. 25 and 26, the surface acoustic wave resonator further includes a passivation layer 5, and the passivation layer 5 is located between the electrode layer 2 and the mass loading layer 3.

Further, the first mass-load unit 31 also extends above the busbar 211 and/or the second mass-load unit 32 also extends above the busbar 211. Referring to fig. 27, an effect diagram of the change of admittance (susceptance) with frequency of the saw resonator having the structure shown in fig. 25 is shown, wherein a curve A6 and a curve B6 are the admittance and the conductance change curves corresponding to the resonator, respectively, and compared with a curve A1 and a curve B1, respectively, the conductance characteristic and the admittance characteristic of the saw resonator having the structure shown in fig. 25 at each frequency are improved, and the mechanical coupling coefficient is reduced.

In an embodiment, with the passivation layer 5, the second mass-loading unit 32 also extends above the gap 214, please refer to fig. 28 and 29, wherein fig. 28 shows a schematic top view of the saw resonator, and fig. 29 shows a schematic longitudinal cross-sectional view of fig. 28 and a schematic propagation speed of the acoustic wave in different regions, and at the same time, the first mass-loading unit 31 also extends into the gap region to be level with the second mass-loading unit 32. Referring to fig. 30, an effect diagram of the change of admittance (susceptance) with frequency of the saw resonator having the structure shown in fig. 28 is shown, wherein a curve A7 and a curve B7 are the admittance and the conductance change curves corresponding to the resonator, respectively, and compared with a curve A1 and a curve B1, respectively, the conductance characteristic and the admittance characteristic of the saw resonator having the structure shown in fig. 27 at each frequency are improved, and the mechanical coupling coefficient k2 is reduced.

The surface acoustic wave resonator of the embodiment can reduce leakage of transverse energy from the virtual finger area and the bus area, thereby improving conductivity and admittance characteristics of the surface acoustic wave resonator in a frequency interval between a resonant frequency and an anti-resonant frequency.

Example five

The present embodiment provides a surface acoustic wave resonator, which is different from the surface acoustic wave resonator in the first embodiment in that: the interdigital transducer in the surface acoustic wave resonator in this embodiment includes a bar (first bar and/or second bar), whereas the surface acoustic wave resonator in the first embodiment does not include the bar.

Specifically, referring to fig. 31 and 9 in combination, fig. 31 is a schematic top view of the saw resonator, the saw resonator includes a semiconductor layer 1, an electrode layer 2, and a mass loading layer 3, wherein the mass loading layer 3 is located above the electrode layer 2, the mass loading layer 3 includes a plurality of first mass loading units 31 and a plurality of second mass loading units 32, the first mass loading units 31 are located above an end of the electrode finger 212 connected to the bus 211, and the second mass loading units 32 are located above the virtual finger 213.

As an example, referring to fig. 32, a schematic top view of the electrode layer in fig. 31 is shown, where the interdigital electrode further includes a first strip 215 extending along the second direction, and the first strip 215 overlaps the virtual finger 213 and the electrode finger 212 partially. Referring to fig. 33, an effect diagram of the change of admittance (susceptance) with frequency of the saw resonator having the structure shown in fig. 31 is shown, wherein a curve A8 and a curve B8 are respectively corresponding to the admittance and the conductance change curve of the resonator, and compared with a curve A1 and a curve B1, respectively, the conductance characteristic and the admittance characteristic of the saw resonator having the structure shown in fig. 31 are improved.

As an example, the width (the distance between two sides perpendicular to the extending direction) of the first strip 215 is smaller than or equal to the length of the virtual finger, that is, the first strip 215 may be only partially overlapped with the virtual finger or completely overlapped with the virtual finger, which is set based on actual needs, and in this embodiment, the first strip is only partially overlapped with the virtual finger, which is equivalent to keeping a certain distance between the first strip and the bus bar adjacent thereto.

As an example, in the same interdigital electrode, the width of the portion of the electrode finger 212 between the bus bar 211 and the first bar 215 is greater than or equal to the width of the portion of the electrode finger 212 between the first bar 215 and the gap 214, and the width of the dummy finger 213 is equal to the width of the portion of the electrode finger 212 between the bus bar 211 and the first bar 215. In this embodiment, the portion of the electrode finger 212 between the bus bar 211 and the first bar 215 is equal to the width of the portion of the electrode finger 212 between the first bar 215 and the gap 214. And further, the width of the first mass-loading unit 31 is greater than or equal to the width of the portion of the electrode finger 212 located between the bus bar 211 and the first bar 215, and the width of the second mass-loading unit 32 is greater than or equal to the width of the dummy finger 213.

As an example, the semiconductor layer 1 further includes a substrate layer 12 (not shown in fig. 31, please refer to fig. 12 in combination) located below the piezoelectric material layer 11, where the substrate layer 12 is a Si substrate or a Si substrate having an oxide layer on a surface (i.e., a POI substrate is formed with the piezoelectric material layer 11), when the substrate layer 12 is a Si substrate, the SAW resonator is a conventional SAW, and when the substrate layer 12 is a Si substrate having an oxide layer on a surface, the SAW resonator is a POI-SAW.

As an example, referring to fig. 34, a schematic top view of a SAW resonator with a temperature compensation layer is shown, where the SAW resonator may further include a temperature compensation layer 4 according to actual needs, and the temperature compensation layer 4 covers the electrode layer 2 and the mass load layer 3, that is, in the case of having the temperature compensation layer 4, the SAW resonator is a TC-SAW.

Further, in other embodiments, each of the reflective gratings 22 further includes two second strips 223 extending along the second direction, and the second strips 223 partially overlap with the plurality of reflective gratings 222 (as shown in fig. 35). Referring to fig. 36, an effect diagram of the change of admittance (susceptance) with frequency of the saw resonator having the structure shown in fig. 35 is shown, wherein a curve A9 and a curve B9 are corresponding to the admittance and the conductance change curve of the resonator, respectively, and compared with a curve A1 and a curve B1, respectively, the conductance characteristic and the admittance characteristic of the saw resonator having the structure shown in fig. 35 at each frequency are improved.

As an example, the width of the second strip is consistent or inconsistent with the width of the first strip, and the second strip is flush or not flush with the first strip (flush refers to the coincidence of the extending directions of the two strips, and not flush refers to the parallel of the extending directions of the two strips), in this embodiment, the second strip is flush with the first strip and has the same width, and of course, in practical application, the second strip and the first strip can be reasonably arranged based on practical needs, but it is required to ensure that the extending direction of the second strip passes through the virtual finger area, so as to achieve the effect of reducing the lateral energy diffusion.

When the surface acoustic wave has the first strip and/or the second strip, the first mass loading unit and the second mass loading unit further cover the region where the electrode finger and the virtual finger partially overlap the first strip (i.e., the region where the electrode finger or the virtual finger partially overlap is provided as a part of the electrode finger or the virtual finger), and similarly, the third mass loading unit further covers the region where the reflection grid partially overlaps the second strip.

As an example, both the first and second mass-load units 31, 32 may also extend above the bus bar 211.

According to the surface acoustic wave resonator, the first strip-shaped piece overlapped with the virtual finger and the electrode finger part is arranged in the interdigital electrode (even the second strip-shaped piece overlapped with the reflecting grating strip part is arranged in the reflecting grating), the first mass load unit and the second mass load unit are respectively arranged above the part of the virtual finger and the electrode finger, which are positioned in the virtual finger area (even extend to the bus area), the propagation speed of the surface acoustic wave in the corresponding area is reduced by utilizing the mass load effect brought by the mass load unit, so that the propagation speed of the surface acoustic wave in the specific area is lower than that of the surface acoustic wave in the electrode finger area, the transverse energy leakage of the surface acoustic wave in the specific area when the surface acoustic wave propagates in the interdigital ring energy device can be reduced, the conductivity characteristic and the admittance characteristic of the surface acoustic wave resonator in the frequency interval between the resonance frequency and the anti-resonance frequency are improved, and the quality factor of the surface acoustic wave resonator is effectively improved.

Example six

The difference between the surface acoustic wave resonator provided in the present embodiment and the surface acoustic wave resonator in the fifth embodiment is that: in the surface acoustic wave resonator of the present embodiment, the width of the portion of the electrode finger between the bus bar and the first bar is larger than the width of the portion of the electrode finger between the first bar and the gap, and the width of the portion of the electrode finger between the bus bar and the first bar is equal to the width of the portion of the electrode finger between the first bar and the gap.

Specifically, referring to fig. 37 and 9 in combination, fig. 37 shows a schematic top view of the saw resonator, the saw resonator includes a semiconductor layer 1, an electrode layer 2 and a mass loading layer 3, wherein the mass loading layer 3 is located above the electrode layer 2, the mass loading layer 3 includes a plurality of first mass loading units 31 and a plurality of second mass loading units 32, the first mass loading units 31 are located above an end of the electrode finger 212 connected to the bus 211, and the second mass loading units 32 are located above the virtual finger 213.

As an example, the interdigital electrode further includes a first bar 215 extending in the second direction, the first bar 215 partially overlapping the virtual finger 213 and the electrode finger 212.

As an example, in the same interdigital electrode, the width of the portion of the electrode finger 212 between the bus bar 211 and the first bar 215 is greater than or equal to the width of the portion of the electrode finger 212 between the first bar 215 and the gap 214, and the width of the virtual finger 213 is equal to the width of the portion of the electrode finger 212 between the bus bar 211 and the first bar 215. In this embodiment, as shown in fig. 37, the portion of the electrode finger 212 between the bus bar 211 and the first bar 215 is larger than the width of the portion of the electrode finger 212 between the first bar 215 and the gap 214. By the arrangement, the distance between the part of the adjacent electrode finger 212 positioned in the virtual finger area and the virtual finger 213 can be reduced, and the propagation speed of the surface acoustic wave in the virtual finger area can be further reduced by combining the mass loading effect and the space modulation effect brought by the mass loading unit.

Further, the width of the first mass-loading unit 31 is smaller than or equal to the width of the portion of the electrode finger 212 located between the bus bar 211 and the first bar 215, the width of the second mass-loading unit 32 is smaller than or equal to the width of the virtual finger 213, and the width of the first mass-loading unit 31 is equal to or different from the width of the second mass-loading unit 32. Specifically, referring to fig. 38, an effect diagram of the change of admittance (susceptance) with frequency of the saw resonator having the structure shown in fig. 37 is shown, wherein a curve a10 and a curve B10 are respectively corresponding to the admittance and the conductance change curve of the resonator, and compared with a curve A1 and a curve B1, respectively, the conductance characteristic and the admittance characteristic of the saw resonator having the structure shown in fig. 37 at each frequency are improved.

In other embodiments, each of the reflective gratings 22 further includes two second strips 223 extending along the second direction, and the second strips 223 partially overlap with the plurality of reflective gratings 222 (as shown in fig. 39). Referring to fig. 40, an effect diagram of the change of admittance (susceptance) with frequency of the saw resonator having the structure shown in fig. 39 is shown, wherein a curve a11 and a curve B11 are the admittance and the conductance change curves corresponding to the resonator, respectively, and compared with a curve A1 and a curve B1, respectively, the conductance characteristic and the admittance characteristic of the saw resonator having the structure shown in fig. 39 at each frequency are improved.

According to the surface acoustic wave resonator of the embodiment, the first strip-shaped piece overlapped with the virtual finger and the electrode finger part is arranged in the interdigital electrode (even the second strip-shaped piece overlapped with the reflecting grating strip part is arranged in the reflecting grating), the first mass load unit and the second mass load unit are respectively arranged above the virtual finger and the electrode finger part positioned in the virtual finger area (even extend to the bus area), the width of the electrode finger part positioned in the virtual finger area and the width of the virtual finger part are further increased to combine the mass load effect and the space modulation effect brought by the mass load unit so as to reduce the propagation speed of the surface acoustic wave in the specific area, so that the propagation speed of the surface acoustic wave in the specific area is lower than the propagation speed of the surface acoustic wave in the electrode finger area, the transverse energy leakage of the surface acoustic wave in the specific area when the surface acoustic wave propagates in the interdigital transducer can be reduced, the conductivity characteristic and the admittance characteristic of the surface acoustic wave resonator in the frequency interval between the resonance frequency and the antiresonance frequency are improved, and the quality factor of the surface acoustic wave resonator is effectively improved.

Example seven

The present embodiment provides a surface acoustic wave resonator, which is different from the surface acoustic wave resonator in the first embodiment in that: in this embodiment, the width of the electrode finger is adjusted to be equal to the width of the dummy finger in order to provide the mass loading layer, whereas in the first embodiment, the mass loading layer is provided and the entire width of the electrode finger is kept uniform.

Specifically, referring to fig. 41 and 42, fig. 41 is a schematic top view of the saw resonator, fig. 42 is a schematic longitudinal cross-sectional view of the structure shown in fig. 41 and a schematic corresponding acoustic wave propagation velocity distribution, the saw resonator includes a semiconductor layer 1 and an electrode layer 2, and the semiconductor layer 1 includes a piezoelectric material layer 11; the electrode layer 2 is located on the piezoelectric material layer 11, the electrode layer 2 includes an interdigital transducer 21, the interdigital transducer 21 includes two interdigital electrodes disposed opposite to each other in a first direction, each interdigital electrode includes a bus bar 211, a plurality of electrode fingers 212 connected to the bus bar 211 and extending in the first direction, and a plurality of dummy fingers 213, the plurality of electrode fingers 212 and the plurality of dummy fingers 213 in the same interdigital electrode are alternately arranged in a second direction, the dummy fingers 213 in the two interdigital electrodes are opposite to the electrode fingers 212 and have gaps 214, and the second direction is perpendicular to the first direction.

As an example, as shown in fig. 41, the width of the portion of the electrode finger located in the virtual finger region is greater than the width of the portion of the electrode finger located in the gap region and the width of the portion of the electrode finger located in the electrode finger region (i.e., i > j shown in fig. 41), and the width of the virtual finger is preferably consistent with the width of the portion of the electrode finger located in the virtual finger region to further reduce lateral energy spread. That is, on the basis of the conventional surface acoustic wave resonator structure (as shown in fig. 1), the width of the portion of the widened electrode finger located in the virtual finger region (may be symmetrically widened with respect to the left and right sides of the original electrode finger or only one or both sides may be widened but the degree of widening is different, etc., and an appropriate widening manner is selected based on actual needs) to realize the electrode finger structure of the present embodiment.

The surface acoustic wave resonator of the embodiment adjusts the width of the electrode finger (even the width of the virtual finger) on the basis of a general surface acoustic wave resonator (increases the width of the part of the electrode finger located in the virtual finger area and keeps the width of the part of the electrode finger except the virtual finger area unchanged), so that the propagation speed of the surface acoustic wave in the area with larger width of the electrode finger is reduced (that is, the propagation speed of the surface acoustic wave in the virtual finger area is lower than that in the electrode finger area) to reduce transverse energy leakage to a certain extent, the conductivity characteristic and admittance characteristic of the frequency interval between the resonant frequency and the antiresonant frequency of the surface acoustic wave resonator are improved, and the quality factor of the surface acoustic wave resonator is effectively improved.

In addition, in other embodiments, the saw resonator may have various structural layers or structures as described in embodiments one to six on the basis of the structure of the present embodiment, for example, in an embodiment, the saw resonator is fabricated such that the width of the electrode finger in the virtual finger area of the interdigital transducer is relatively larger than the width of the electrode finger in the gap area and the electrode finger area, and a mass loading layer is disposed on the electrode layer, so as to improve the quality factor and the working performance of the resonator in cooperation with the dual reduction of the transverse energy diffusion effect of the electrode finger width adjustment and the mass loading layer. In another embodiment, the saw resonator may further include a passivation layer, a first strip, a second strip, a substrate replacing structure, and the like based on the structure of the foregoing embodiment, and the various structures of the first to seventh embodiments may be adjusted and deformed based on actual needs in practical application.

Example eight

The invention also provides a manufacturing method of the surface acoustic wave resonator, which is used for manufacturing the surface acoustic wave resonator or the resonator with other suitable structures according to any one of the first to seventh embodiments, and specifically comprises the following steps:

Providing a semiconductor layer comprising a layer of piezoelectric material;

forming an electrode layer on the piezoelectric material layer, the electrode layer including an interdigital transducer including two interdigital electrodes disposed opposite each other in a first direction, each of the interdigital electrodesThe interdigital electrodes comprise bus bars, a plurality of electrode fingers connected with the bus bars and extending in a first direction and virtual fingers, the electrode fingers and the virtual fingers in the same interdigital electrode are alternately arranged at intervals in a second direction, the virtual fingers in the two interdigital electrodes are opposite to the electrode fingers and have gaps, and the second direction is perpendicular to the first direction; the surface acoustic wave resonator is characterized in that electrode finger areas (IDTs), gap areas (gaps), virtual finger areas (dummy IDTs) and Bus areas (Bus-bars) are sequentially arranged on two sides of the center line of the surface acoustic wave resonator in the first direction. When a surface acoustic wave propagates through the surface acoustic wave resonator, the propagation velocity of the surface acoustic wave in the electrode finger region is between the propagation velocity of the surface acoustic wave in the gap region and the propagation velocity of the surface acoustic wave in the virtual finger region, and the propagation velocity of the surface acoustic wave in the bus region is less than or equal to the propagation velocity of the surface acoustic wave in the electrode finger region (i.e., vgap > V _IDT ≥V _Bus-bar ＞V _dummy _IDT )。

As an example, the saw resonator further comprises a mass loading layer, the mass loading layer being located above the electrode layer, the mass loading layer comprising a plurality of first mass loading units and/or a plurality of second mass loading units, the first mass loading units being located above the end of the electrode finger connected to the busbar, the second mass loading units being located above the virtual finger. In yet other embodiments, the width of the portion of the electrode finger located in the virtual finger region is greater than the width of the portion of the electrode finger located in the gap region and the width of the portion of the electrode finger located in the electrode finger region (i.e., i > j in fig. 41), the width of the virtual finger preferably being consistent with the width of the portion of the electrode finger located in the virtual finger region to further reduce lateral energy spread.

The manufacturing method of the surface acoustic wave resonator can manufacture the surface acoustic wave resonator with high quality factor and excellent working performance based on actual requirements.

In summary, according to the surface acoustic wave resonator of the present invention, the first mass loading unit and the second mass loading unit are respectively disposed above the portions of the virtual finger and the electrode finger located in the virtual finger area (even extend to the bus area), so as to reduce the propagation speed of the surface acoustic wave in the virtual finger area by using the mass loading effect, and/or increase the width of the portion of the electrode finger located in the virtual finger area so as to reduce the propagation speed of the surface acoustic wave in the virtual finger area, so that the propagation speed of the surface acoustic wave in the virtual finger area is lower than the propagation speed of the surface acoustic wave in the electrode finger area to reduce the transverse energy leakage to a certain extent, thereby improving the conductivity characteristic and the admittance characteristic of the surface acoustic wave resonator in the frequency interval between the resonant frequency and the anti-resonant frequency, effectively improving the working performance of the surface acoustic wave resonator. The manufacturing method of the surface acoustic wave resonator can be used for manufacturing the surface acoustic wave resonator with high quality factor and excellent working performance based on actual requirements. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. A surface acoustic wave resonator, comprising:

a semiconductor layer including a piezoelectric material layer;

2. The surface acoustic wave resonator according to claim 1, characterized in that: the surface acoustic wave resonator further comprises a mass load layer, wherein the mass load layer is positioned above the electrode layer, the mass load layer comprises a plurality of first mass load units and/or a plurality of second mass load units, the first mass load units are positioned above one ends, connected with the bus, of the electrode fingers, and the second mass load units are positioned above the virtual fingers.

3. The surface acoustic wave resonator according to claim 2, characterized in that: the SAW resonator further includes a passivation layer positioned between the electrode layer and the mass loading layer.

4. A surface acoustic wave resonator according to claim 3, characterized in that: when the mass loading layer includes the second mass loading unit, the second mass loading unit also extends above the gap.

5. The surface acoustic wave resonator according to claim 2, characterized in that: the interdigital electrode further comprises a first strip extending along a second direction, and the first strip is partially overlapped with the virtual finger and the electrode finger.

6. The surface acoustic wave resonator according to claim 5, characterized in that: in the same interdigital electrode, the width of the part of the electrode finger between the bus bar and the first strip is larger than or equal to the width of the part of the electrode finger between the first strip and the gap, and the width of the virtual finger is equal to the width of the part of the electrode finger between the bus bar and the first strip.

7. The surface acoustic wave resonator according to claim 2, characterized in that: the first mass-load unit also extends above the busbar and/or the second mass-load unit also extends above the busbar.

8. The surface acoustic wave resonator according to claim 2, characterized in that: the electrode layer further comprises two reflecting grids, the two reflecting grids are respectively arranged on two sides of the interdigital transducer in the second direction, each reflecting grid comprises a plurality of reflecting grids extending in the first direction, and the reflecting grids are arranged at intervals in the second direction; the mass loading layer further comprises a plurality of third mass loading units located above both ends of the reflection grid in the first direction.

9. The surface acoustic wave resonator according to claim 8, characterized in that: each of the reflective gratings further includes two second bars extending in a second direction, the second bars partially overlapping the plurality of reflective gratings.

10. The surface acoustic wave resonator according to claim 2, characterized in that: the metallization rate of the interdigital electrode ranges from 0.3 to 0.7, and the pitch of the virtual finger is 100% -130% of the pitch of the electrode finger; when the distance between two adjacent electrode fingers in the same interdigital electrode is lambda, the aperture range of the interdigital transducer is 10 lambda-50 lambda, the length range of the gap is 0.025 lambda-2.0 lambda, the width range of the virtual finger is 0.025 lambda-2.0 lambda, and the thickness range of the electrode finger is 0.025 lambda-0.15 lambda.

11. The surface acoustic wave resonator according to claim 10, characterized in that: the material of the mass loading layer comprises at least one of Al, ti, cu, pt, mo, W, cr and Au, and the thickness range of the mass loading layer is 0.0025lambda-0.125lambda.

12. The surface acoustic wave resonator according to claim 1 or 2, characterized in that: the width of the portion of the electrode finger located in the virtual finger region is greater than the width of the portion of the electrode finger located in the gap region and the width of the portion of the electrode finger located in the electrode finger region.

13. The manufacturing method of the surface acoustic wave resonator is characterized by comprising the following steps of:

providing a semiconductor layer comprising a layer of piezoelectric material;