Saw resonator device

Abstract

The utility model provides an SAW resonator device, which comprises a substrate layer, a piezoelectric layer and an electrode layer, the piezoelectric layer is arranged on one side of the substrate layer, and the piezoelectric layer is provided with a second interface facing the substrate layer and a first interface far away from the substrate layer relative to the second interface. The piezoelectric layer is provided with at least one sinking area which sinks from the first interface to the second interface; the electrode layer is arranged on the first interface and provided with an interdigital transducer and two oppositely-arranged bus bars, the interdigital transducer comprises two sets of finger bars distributed in a staggered mode, one set of finger bars are connected to one bus bar, a gap area is formed at the position where the distance between the bus bars and the ends of the finger bars is the shortest, and the gap area is located between the bus bars and the ends of the finger bars. At least a portion of the bus bar and at least a portion of the gap region are located within the sink region. According to the utility model, the problems that the SAW resonator device in the prior art has a suppression transverse mode and is easy to process and difficult to consider at the same time are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of communication equipment, and particularly to a SAW resonator device. Background Technique

[0002] With the advent of the 5G mobile communication era, radio frequency filters play an increasingly important role in mobile terminals, and the characteristics of circuit elements such as filters are closely related to the performance of resonators. Traditional Surface Acoustic Wave (SAW) resonators usually face many problems such as low quality factor, poor power tolerance, and poor frequency temperature coefficient. Among them, the most important problem is that when the SAW main mode is excited, a transverse acoustic wave mode propagating along the finger electrodes, i.e., the aperture direction, will also be generated, and this phenomenon is particularly obvious in multi-layer SAW resonators. The generated transverse mode will form spurious responses in the regions of the forward and reverse resonance points of the SAW resonator device response, resulting in an increase in the insertion loss and in-band ripple of the synthesized acoustic filter, which is not conducive to improving the performance of the SAW resonator device.

[0003] In the existing techniques for suppressing the transverse mode, the method of increasing the metal duty ratio or mass loading at the ends of the finger electrodes can form a velocity trap in this region, which can effectively suppress acoustic wave leakage and achieve the purpose of suppressing the transverse acoustic wave mode. However, this technique has extremely high requirements for the precision of the manufacturing process, and problems such as misalignment leading to short circuits may occur when the mass loading is small or the duty ratio is too large.

[0004] That is to say, there is a problem in the existing SAW resonator device that it is difficult to balance suppressing the transverse mode and being easy to process. Summary of the Utility Model

[0005] The main purpose of the utility model is to provide a SAW resonator device to solve the problem in the existing SAW resonator device that it is difficult to balance suppressing the transverse mode and being easy to process.

[0006] To achieve the above purpose, according to one aspect of the utility model, a SAW resonator device is provided, including: a substrate layer; a piezoelectric layer disposed on one side of the substrate layer, the piezoelectric layer having a second interface facing the substrate layer and a first interface away from the substrate layer relative to the second interface, the piezoelectric layer having at least one sinking area sunken from the first interface towards the second interface; an electrode layer disposed on the first interface, the electrode layer having an interdigital transducer and two oppositely disposed bus bars, the interdigital transducer including two groups of alternately distributed finger bars, one group of finger bars being connected to one bus bar, the shortest distance between the end of the bus bar and the finger bar forming a gap area, and at least a part of the bus bar and at least a part of the gap area being located in the sinking area.

[0007] According to another aspect of the present utility model, there is provided a SAW resonator device, comprising: a substrate layer; a piezoelectric layer disposed on one side of the substrate layer, the piezoelectric layer having a second interface facing the substrate layer and a first interface away from the substrate layer relative to the second interface, the piezoelectric layer having at least one sunken area sunken in the direction from the first interface to the second interface; a filling layer disposed in the sunken area, the filling layer being made of a material different from that of the piezoelectric layer; an electrode layer disposed on the first interface, the electrode layer having an interdigital transducer and two oppositely disposed bus bars, the interdigital transducer comprising two sets of alternately distributed finger bars, one set of finger bars being connected to one bus bar, a gap area being formed at the shortest distance between the end of the bus bar and the finger bar, and at least a part of the bus bar and at least a part of the gap area being within the range of the projection of the sunken area on the first interface.

[0008] Further, the depth h of the sunken area and the minimum thickness H1 of the electrode layer satisfy: 0 < h < H1.

[0009] Further, the minimum thickness H1 of the electrode layer and the operating wavelength λ of the interdigital transducer satisfy: 0.05λ < H1 < 0.1λ.

[0010] Further, the maximum thickness H2 of the piezoelectric layer and the operating wavelength λ of the interdigital transducer satisfy: 0.1λ < H2 < 0.5λ.

[0011] Further, the SAW resonator device has at least one side wall surface extending perpendicular to the substrate layer, and the sunken area extends to the side wall surface.

[0012] Further, the piezoelectric layer has two spaced-apart sunken areas, and the two sunken areas are arranged in one-to-one correspondence with the two bus bars.

[0013] Further, the surface of the electrode layer away from the first interface is a plane.

[0014] Further, the surface of the electrode layer away from the first interface has the same shape as the first interface.

[0015] Further, the SAW resonator device further comprises a dielectric layer disposed on the surface of the electrode layer away from the first interface, and the surface of the dielectric layer away from the electrode layer is a plane.

[0016] Further, the material of the dielectric layer includes at least one of silicon oxide, aluminum nitride, glass, tantalum oxide, polysilicon, silicon nitride, silicon oxynitride, and a compound of silicon oxide doped with fluorine or carbon or boron.

[0017] Further, at least one of the dielectric constant and the conductivity of the material of the filling layer is different from that of the material of the piezoelectric layer.

[0018] Further, the material of the filling layer includes at least one of silicon oxide, aluminum nitride, glass, tantalum oxide, polysilicon, silicon nitride, silicon oxynitride, and a compound obtained by doping silicon oxide with fluorine, carbon, or boron.

[0019] Further, the material of the substrate layer includes at least one of silicon, sapphire, diamond, and silicon carbide; and / or the material of the piezoelectric layer includes at least one of lithium tantalate, lithium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, and lead zirconate titanate; and / or the material of the electrode layer includes at least one of nickel, molybdenum, iron, copper, tungsten, gold, silver, aluminum, and platinum.

[0020] Further, the SAW resonator device further includes a low acoustic velocity layer and a high acoustic velocity layer, and the piezoelectric layer, the low acoustic velocity layer, the high acoustic velocity layer, and the substrate layer are sequentially connected.

[0021] Further, the material of the low acoustic velocity layer includes at least one of silicon oxide, aluminum nitride, glass, tantalum oxide, or a compound obtained by doping silicon oxide with fluorine, carbon, or boron; and / or the material of the high acoustic velocity layer is different from the material of the substrate layer, and the material of the high acoustic velocity layer includes at least one of polysilicon, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon, sapphire, and diamond.

[0022] According to another aspect of the present invention, a method for manufacturing a SAW resonator device is provided. The method for manufacturing a SAW resonator device is used to manufacture the above-mentioned SAW resonator device, and the method for manufacturing a SAW resonator device includes: providing a piezoelectric layer of the SAW resonator device; etching a preset depth on a first interface of the piezoelectric layer to obtain a sinking area of the piezoelectric layer; and processing an interdigital transducer of the SAW resonator device on one side of the first interface to obtain an electrode layer of the SAW resonator device.

[0023] Further, in the process of processing the interdigital transducer of the SAW resonator device on one side of the first interface of the piezoelectric layer to obtain the electrode layer of the SAW resonator device, it includes: processing at least a part of the bus bar of the interdigital transducer above the sinking area.

[0024] Further, in the process of processing the interdigital transducer of the SAW resonator device on one side of the first interface of the piezoelectric layer to obtain the electrode layer of the SAW resonator device, it includes: processing the electrode layer on the first interface by using a photolithography process and a lift-off process.

[0025] Further, the SAW resonator device further includes a low acoustic velocity layer and a high acoustic velocity layer, and the high acoustic velocity layer, the low acoustic velocity layer, and the piezoelectric layer are sequentially stacked on the substrate layer. The method for manufacturing a SAW resonator device further includes: providing a substrate layer of the SAW resonator device; forming a high acoustic velocity layer on the substrate layer by chemical vapor deposition; forming a low acoustic velocity layer on the high acoustic velocity layer by thermal oxidation; and thermally bonding the low acoustic velocity layer and the piezoelectric layer together by a bonding process.

[0026] Applying the technical solution of the present utility model, the SAW resonator device includes a substrate layer, a piezoelectric layer, and an electrode layer. The piezoelectric layer is disposed on one side of the substrate layer. The piezoelectric layer has a second interface facing the substrate layer and a first interface away from the substrate layer relative to the second interface. The piezoelectric layer has at least one sunken area sunken from the first interface to the second interface; the electrode layer is disposed on the first interface. The electrode layer has an interdigital transducer and two oppositely disposed bus bars. The interdigital transducer includes two sets of interleaved finger bars. One set of finger bars is connected to one bus bar. The shortest distance between the end of the bus bar and the finger bar forms a gap area. At least a part of the bus bar and at least a part of the gap area are located in the sunken area.

[0027] In this embodiment, the SAW resonator device disposes the electrode layer on the first interface of the piezoelectric layer. Along the direction from the first interface to the second interface, the piezoelectric layer has at least one sunken area formed by etching. An interdigital transducer is disposed on the electrode layer. The bus bar of the interdigital transducer is disposed near the edge of the electrode layer, which helps the SAW resonator device collect signal current. The lengths of multiple finger bars are the same and are arranged in a comb shape, laid from one bus bar to the other bus bar and not contacting the other bus bar. The non-contact vertical area forms a gap area, that is, the shortest distance between the end of the bus bar and the finger bar forms a gap area, creating a structural condition for exciting the SAW main mode. At the same time, at least a part of the bus bar and the gap area are located in the sunken area, making the cross-section of the end of the finger bar and a part of the piezoelectric layer an air surface, further forming a discontinuous structural condition. The acoustic impedance of air is much larger than the acoustic impedance of the material of the piezoelectric layer and the metal material of the finger bar. According to the discontinuity of the acoustic impedance, the acoustic wave energy is restricted to the position without the sunken area and will not continue to leak to the outside, thereby suppressing the lateral acoustic wave mode of the SAW resonator device and improving the Q value of the SAW resonator device. In addition, directly disposing the electrode layer on the piezoelectric layer eliminates the secondary metal coating and the occurrence of metal short circuits, reducing the process cost and greatly improving the reliability. Description of the Drawings

[0028] The specification drawings forming a part of this application are used to provide a further understanding of the present utility model. The schematic embodiments of the present utility model and their descriptions are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0029] Figure 1 A side view of the SAW resonator device according to Embodiment 1 of the present utility model is shown;

[0030] Figure 2 A side view of the SAW resonator device according to Embodiment 2 of the present utility model is shown;

[0031] Figure 3 Shown is Figure 2Schematic top view, side view and acoustic impedance distribution diagrams of corresponding regions of the SAW resonator device in

[0032] Figure 4 show Figure 2 Admittance and real part of admittance curves of the SAW resonator device in at the low frequency band;

[0033] Figure 5 show Figure 2 Admittance and real part of admittance curves of the SAW resonator device in at the medium frequency band;

[0034] Figure 6 Show the side view of the SAW resonator device of Embodiment III of the present invention;

[0035] Figure 7 Show the side view of the SAW resonator device of Embodiment IV of the present invention;

[0036] Figure 8 Show the side view of the SAW resonator device of Embodiment V of the present invention;

[0037] Figure 9 Show the flowchart of the manufacturing method of the SAW resonator device of an alternative embodiment of the present invention;

[0038] Figure 10 Show the process flowchart of the SAW resonator device of an alternative embodiment of the present invention;

[0039] Figure 11 Show the side view of a resonator in the prior art;

[0040] Figure 12 show Figure 11 Schematic top view, side view and acoustic impedance distribution diagrams of corresponding regions of the resonator in ;

[0041] Figure 13 show Figure 11 Admittance and real part of admittance curves of the resonator in at the low frequency band;

[0042] Figure 14 show Figure 11 Admittance and real part of admittance curves of the resonator in at the medium frequency band.

[0043] Among them, the above-mentioned drawings include the following reference numerals:

[0044] 10, sunken area; 21, electrode layer; 22, piezoelectric layer; 23, low acoustic velocity layer; 24, high acoustic velocity layer; 25, substrate layer; 26, dielectric layer; 27, filling layer. Detailed implementation manners

[0045] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will describe the present utility model in detail with reference to the drawings and in combination with the embodiments.

[0046] It should be pointed out that, unless otherwise specified, all technical and scientific terms used in the present application have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0047] In the present utility model, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are usually in reference to the directions shown in the drawings, or in reference to the vertical, perpendicular or gravitational directions of the components themselves; similarly, for ease of understanding and description, "inner, outer" refer to the inner and outer relative to the contours of the components themselves, but the above orientation terms are not used to limit the present utility model.

[0048] In order to solve the problem in the prior art that it is difficult to balance the suppression of the lateral mode and the ease of processing in a SAW resonator device, the present utility model provides a SAW resonator device.

[0049] As Figures 1 to 10 shown, in an alternative embodiment of the present application, the SAW resonator device includes a substrate layer 25, a piezoelectric layer 22 and an electrode layer 21. The piezoelectric layer 22 is disposed on one side of the substrate layer 25. The piezoelectric layer 22 has a second interface facing the substrate layer 25 and a first interface away from the substrate layer 25 relative to the second interface. The piezoelectric layer 22 has at least one sinking area 10 sunken in the direction from the first interface to the second interface; the electrode layer 21 has an interdigital transducer and two oppositely disposed bus bars. The interdigital transducer includes two sets of interleaved finger bars. One set of finger bars is connected to one bus bar. The shortest distance between the end of the bus bar and the finger bar forms a gap area. At least a part of the bus bar and at least a part of the gap area are located in the sinking area 10.

[0050] In this embodiment, the SAW resonator device disposes the electrode layer 21 on the first interface of the piezoelectric layer 22. Along the direction from the first interface to the second interface, the piezoelectric layer 22 has at least one etched sinking area 10. An interdigital transducer is disposed on the electrode layer 21. The bus bars of the interdigital transducer are disposed close to the edge of the electrode layer 21, which helps the SAW resonator device collect signal current. The lengths of multiple finger bars are the same and are arranged in a comb shape, laid from one bus bar to the other bus bar without contacting the other bus bar. The non-contact vertical area forms a gap area, that is, the gap area is formed at the place where the distance between the bus bar and the end of the finger bar is the shortest, creating a structural condition for exciting the SAW main mode. At the same time, at least a part of the bus bar and the gap area are located in the sinking area 10, so that the cross section of the end of the finger bar and a part of the piezoelectric layer 22 is an air surface, further forming a discontinuous structural condition. The acoustic impedance of air is much larger than the acoustic impedance of the material of the piezoelectric layer 22 and the metal material of the finger bar. According to the discontinuity of the acoustic impedance, the acoustic wave energy is limited to the position without the sinking area 10 and will not continue to leak to the outside, thereby suppressing the lateral acoustic wave mode of the SAW resonator device and at the same time increasing the Q value of the SAW resonator device. In addition, directly disposing the electrode layer 21 on the piezoelectric layer 22 does not have the situation of secondary metal coating and metal short circuit, reducing the process cost and greatly improving the reliability.

[0051] In another embodiment of the present application, as shown in the figure, the SAW resonator device includes a substrate layer 25, a piezoelectric layer 22, a filling layer 27 and an electrode layer 21. The piezoelectric layer 22 is disposed on one side of the substrate layer 25. The piezoelectric layer 22 has a second interface facing the substrate layer 25 and a first interface away from the substrate layer 25 relative to the second interface. The piezoelectric layer 22 has at least one sinking area 10 sinking from the first interface to the second interface; the filling layer 27 is disposed in the sinking area 10, and the filling layer 27 is different from the material of the piezoelectric layer 22; the electrode layer 21 is disposed on the first interface. The electrode layer 21 has an interdigital transducer and two oppositely disposed bus bars. The interdigital transducer includes two sets of alternately distributed finger bars. One set of finger bars is connected to one bus bar. The gap area is formed at the place where the distance between the bus bar and the end of the finger bar is the shortest. At least a part of the bus bar and at least a part of the gap area are within the range of the sinking area 10 in the projection on the first interface.

[0052] In this embodiment, the SAW resonator device disposes the electrode layer 21 on the first interface of the piezoelectric layer 22. Along the direction from the first interface to the second interface, the piezoelectric layer 22 has at least one etched sinking area 10. An interdigital transducer is disposed on the electrode layer 21, and the bus bar of the interdigital transducer is disposed close to the edge of the electrode layer 21, which helps the SAW resonator device to collect signal current. The lengths of multiple finger bars are the same and are arranged in a comb shape, and are laid from one bus bar to the other bus bar without contacting the other bus bar. The non-contact vertical area forms a gap area, that is, the gap area is formed at the place where the distance between the bus bar and the end of the finger bar is the shortest, creating a structural condition for exciting the SAW main mode. Different from the above embodiment, a filling layer 27 is disposed in the sinking area 10, and the material of the filling layer 27 is different from that of the piezoelectric layer 22, providing a velocity barrier for the SAW resonator device. The end of the finger bar and the cross section of a part of the piezoelectric layer 22 are air surfaces or the end surfaces of the filling layer 27, also forming discontinuous structural conditions. The acoustic impedance of air and the material of the filling layer 27 is much larger than the acoustic impedance of the material of the piezoelectric layer 22 and the metal material of the finger bar. According to the discontinuity of the acoustic impedance, the acoustic wave energy is limited to the position without the sinking area 10 and will not continue to leak to the outside, thereby suppressing the lateral acoustic wave mode of the SAW resonator device and improving the Q value of the SAW resonator device. In addition, directly disposing the electrode layer 21 on the piezoelectric layer 22 eliminates the secondary metal coating and the occurrence of metal short circuits, reducing the process cost and greatly improving the reliability.

[0053] Based on the above two embodiments, there is a further optimized design for the SAW resonator device of the present application.

[0054] Preferably, the piezoelectric layer 22 has two sinking areas 10 arranged at intervals, and the two sinking areas 10 are arranged in one-to-one correspondence with the two bus bars. That is to say, the aperture area of the SAW resonator device corresponds to the unetched part of the piezoelectric layer 22 and is located between the two sinking areas 10. In this way, the lateral acoustic wave mode can be suppressed within the two sinking areas 10, that is, within the aperture area, further improving the Q value of the SAW resonator device. The two sinking areas 10 arranged at intervals correspond to the positions of the bus bars on the electrode layer 21 one by one, which is beneficial to enhancing the coupling between the electrode layer 21 and the acoustic wave, improving the frequency selectivity of the interdigital transducer, and improving the acoustic-electric conversion efficiency of the SAW resonator device.

[0055] As Figure 1 shown, the depth h of the sinking area 10 and the minimum thickness H1 of the electrode layer 21 satisfy: 0 < h < H1. By reasonably restricting the minimum thickness H1 of the electrode layer 21 to be greater than the depth h of the sinking area 10, it not only meets the etching depth condition of the sinking area 10, but also avoids a large bend of the finger bars on the electrode layer 21 relative to the bus bars, enhancing the structural rationality and processability of the SAW resonator device.

[0056] AsFigure 1 As shown, the minimum thickness H1 of the electrode layer 21 and the operating wavelength λ of the interdigital transducer satisfy: 0.05λ < H1 < 0.1λ. That is to say, when the minimum thickness H1 of the electrode layer 21 is limited between 0.05λ and 0.1λ, the hindrance to the propagation of acoustic waves can be reduced, while maintaining sufficient conductivity, avoiding reducing the coupling efficiency between the acoustic waves and the electrode layer 21.

[0057] As Figure 1 shown, the maximum thickness H2 of the piezoelectric layer 22 and the operating wavelength λ of the interdigital transducer satisfy: 0.1λ < H2 < 0.5λ. By limiting H2 within a reasonable range, the thickness of the maximum thickness H2 of the piezoelectric layer 22 can be sufficient to support effective acoustic wave excitation, while also avoiding excessive thickness of the piezoelectric layer 22 resulting in increased attenuation of acoustic waves.

[0058] Optionally, the SAW resonator device has at least one side wall surface extending perpendicular to the substrate layer 25, and the sinking area 10 extends to the side wall surface. That is to say, the etched sinking area 10 of the SAW resonator device can extend to the side wall surface of the substrate layer 25, which is beneficial to enhancing the coupling efficiency of the acoustic waves at the surface of the SAW resonator device and the edge of the side wall surface, thereby improving the performance of the SAW resonator device.

[0059] Optionally, as shown in the figure, the surface of the electrode layer 21 on the side away from the first interface is a plane. That is to say, the surface of the electrode layer 21 away from the piezoelectric layer 22 can be set as a plane, which is beneficial to providing a more uniform electric field distribution and simplifying the manufacturing process of the electrode layer 21 of the SAW resonator device.

[0060] Of course, it can also be set that the surface of the electrode layer 21 on the side away from the first interface is shaped the same as the first interface. That is to say, the surface of the electrode layer 21 away from the piezoelectric layer 22 can be set to be the same as the first interface. On the premise of keeping the thickness of the electrode layer 21 consistent, the shape trends of the electrode layer 21 located in the sinking area 10 and between the two sinking areas 10 are the same as those of the etched piezoelectric layer 22, which is beneficial to the shape of the electrode layer 21 adapting to the propagation path of the acoustic waves and realizing more precise acoustic wave control of the SAW resonator device.

[0061] As Figure 7 shown, the SAW resonator device further includes a dielectric layer 26, and the dielectric layer 26 is disposed on the surface of the electrode layer 21 on the side away from the first interface. The surface of the dielectric layer 26 away from the electrode layer 21 is a plane. That is to say, the dielectric layer 26 on the surface of the electrode layer 21 away from the piezoelectric layer 22 can be set as a plane, reducing the contact of the acoustic waves at the interface between the electrode layer 21 and the air, thereby reducing the loss of the acoustic waves. It can also provide protection for the electrode layer 21.

[0062] Optionally, the material of the dielectric layer 26 includes at least one of silicon oxide, aluminum nitride, glass, tantalum oxide, polysilicon, silicon nitride, silicon oxynitride, and a compound in which silicon oxide is doped with fluorine, carbon, or boron. That is to say, the material of the dielectric layer 26 can cover the electrode layer 21 as a shielding layer and the upper surface of the dielectric layer 26 is flat, reducing external electromagnetic interference.

[0063] Optionally, at least one of the dielectric constant and the conductivity of the material of the filling layer 27 is different from that of the material of the piezoelectric layer 22. Such a setting is beneficial to the propagation of acoustic waves in the piezoelectric layer 22 and adjusts the operating frequency and bandwidth of the SAW resonator device.

[0064] Optionally, the material of the filling layer 27 includes at least one of silicon oxide, aluminum nitride, glass, tantalum oxide, polysilicon, silicon nitride, silicon oxynitride, and a compound in which silicon oxide is doped with fluorine, carbon, or boron. That is to say, filling the portion outside the aperture region of the SAW resonator device with the material of the filling layer 27 is beneficial to reducing the radiation loss at the edge of the electrode layer 21.

[0065] Optionally, the material of the substrate layer 25 includes at least one of silicon, sapphire, diamond, and silicon carbide. Such a setting can provide a high Q factor and improve the performance of the SAW resonator device.

[0066] Optionally, the material of the piezoelectric layer 22 includes at least one of lithium tantalate, lithium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, and lead zirconate titanate. Such a setting can provide a relatively high acoustic-electric conversion efficiency for the SAW resonator device.

[0067] Optionally, the material of the electrode layer 21 includes at least one of nickel, molybdenum, iron, copper, tungsten, gold, silver, aluminum, and platinum. Such a setting can provide a relatively high conductivity and good piezoelectric ability.

[0068] Such as Figure 9As shown, the manufacturing method of the SAW resonator device is used to manufacture the SAW resonator device of any one of the above. The manufacturing method of the SAW resonator device includes: Step S10: providing the piezoelectric layer 22 of the SAW resonator device; Step S20: etching a preset depth on the first interface of the piezoelectric layer 22 to obtain the sunken area 10 of the piezoelectric layer 22; Step S30: processing the interdigital transducer of the SAW resonator device on one side of the first interface to obtain the electrode layer 21 of the SAW resonator device. That is to say, for the piezoelectric layer 22 obtained through Step S10, in Step S20, it is etched to the preset depth from the first interface to the second interface, so as to obtain the sunken area 10 of the piezoelectric layer 22. Finally, according to Step S30, the interdigital transducer of the SAW resonator device is processed on one side of the first interface, and finally the electrode layer 21 of the SAW resonator device is obtained. By directly disposing the electrode layer 21 on the piezoelectric layer 22 that has been etched with the sunken area 10, the structure of the electrode layer 21 will not be damaged again, there is no secondary metal coating and metal short-circuit situation, the process cost is reduced, and the reliability is also greatly improved.

[0069] Specifically, in the process of processing the interdigital transducer of the SAW resonator device on one side of the first interface of the piezoelectric layer 22 to obtain the electrode layer 21 of the SAW resonator device, it includes: processing at least a part of the bus bar of the interdigital transducer above the sunken area 10. That is to say, the sunken area 10 extends laterally below the bus bar, and the sunken area 10 is etched first and then the electrode layer 21 is formed on the first interface, so as to avoid damaging the electrode layer 21.

[0070] Specifically, in the process of processing the interdigital transducer of the SAW resonator device on one side of the first interface of the piezoelectric layer 22 to obtain the electrode layer 21 of the SAW resonator device, it includes processing the electrode layer 21 on the first interface by using a photolithography process and a lift-off process. That is to say, through the precise photolithography process and the selectively processed electrode layer 21 by lift-off, the quality of the interdigital transducer can be improved, and at the same time, the surface of the interdigital transducer can be ensured to be flat, and the acoustic-electric conversion efficiency can be improved.

[0071] Such as Figure 10As shown, the SAW resonator device further includes a low acoustic velocity layer 23 and a high acoustic velocity layer 24. The high acoustic velocity layer 24, the low acoustic velocity layer 23, and the piezoelectric layer 22 are sequentially stacked on the substrate layer 25. The manufacturing method of the SAW resonator device further includes: providing the substrate layer 25 of the SAW resonator device; forming the high acoustic velocity layer 24 on the substrate layer 25 by chemical vapor deposition; forming the low acoustic velocity layer 23 on the high acoustic velocity layer 24 by thermal oxidation; thermally bonding the low acoustic velocity layer 23 and the piezoelectric layer 22 together through a bonding process. By arranging the high acoustic velocity layer 24 and the low acoustic velocity layer 23 between the substrate layer 25 and the piezoelectric layer 22 in the above manner, not only can the SAW resonator device have good processability, but its interlayer structure is also stable. At the same time, the use of different acoustic velocity layers helps the stability of the SAW resonator device at different temperatures.

[0072] As Figures 11 to 14 shows two comparative examples of the prior art without the processing sinking area 10. Among them, as Figure 13 shown, for the resonator applied in the low frequency band, λ = 5.56um, H1 = 0.075λ, H2 = 0.11λ. After simulation, it shows that there are multiple spike burrs in the curve of the real part of the admittance, that is, there is a strong transverse mode response, the insertion loss of the resonator is large, and the Q value is not high. In addition, as Figure 14 shown, for the resonator applied in the middle frequency band, λ = 2um, H1 = 0.085λ, H2 = 0.3λ. It can also be seen from the curve of the real part of the admittance that the spurious response is strong.

[0073] Embodiment 1

[0074] As Figures 1 to 4 shown, the SAW resonator device includes an electrode layer 21, a piezoelectric layer 22, a low acoustic velocity layer 23, a high acoustic velocity layer 24, and a substrate layer 25 connected in sequence. The surface of the electrode layer 21 on the side away from the first interface is formed in the same shape as the first interface. The piezoelectric layer 22 has two spaced sinking areas 10, and the two sinking areas 10 are correspondingly arranged with the two bus bars. In this embodiment, the gap area and the bus bar are both illustrated in the sinking area 10. That is to say, the aperture area of the SAW resonator device corresponds to the unetched part of the piezoelectric layer 22 and is located between the two sinking areas 10.

[0075] The end of the finger bar of the SAW resonator device in this embodiment and the cross-section of a part of the piezoelectric layer 22 are the air surface or the end surface of the filling layer 27, also forming a discontinuous structural condition. The acoustic impedance of air and the material of the filling layer 27 is much larger than that of the material of the piezoelectric layer 22 and the metal material of the finger bar. According to the discontinuity of the acoustic impedance, the acoustic wave energy is restricted within the aperture region and will not leak outwards, thereby suppressing the lateral acoustic wave mode of the SAW resonator device and further improving the Q value of the SAW resonator device. The two sunken areas 10 arranged at intervals correspond one by one to the positions of the bus bars on the electrode layer 21, which is beneficial to enhancing the coupling between the electrode layer 21 and the acoustic wave, improving the frequency selectivity of the interdigital transducer, and improving the acoustic-electric conversion efficiency of the SAW resonator device.

[0076] At the same time, the setting of the low acoustic velocity layer 23 and the high acoustic velocity layer 24 can help the SAW resonator device to control the propagation speed and path of the acoustic wave in different layers and optimize the propagation characteristics of the acoustic wave. At the same time, the use of different acoustic velocity layers helps the stability of the SAW resonator device at different temperatures.

[0077] Optionally, the material of the low acoustic velocity layer 23 includes at least one of silicon oxide, aluminum nitride, glass, tantalum oxide, or a compound doped with fluorine or carbon or boron in silicon oxide. Such a setting can slow down the propagation speed of the acoustic wave on the surface of the SAW resonator device, help to adjust the operating frequency of the SAW resonator device, and at the same time can reduce the propagation loss of the acoustic wave and improve the Q factor of the SAW resonator device.

[0078] Optionally, the material of the high acoustic velocity layer 24 is different from that of the substrate layer 25. The material of the high acoustic velocity layer 24 includes at least one of polysilicon, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon, sapphire, diamond. Such a setting can increase the propagation speed of the acoustic wave on the surface of the SAW resonator device, increase the resonance frequency of the SAW resonator at the same size, and at the same time can accurately control the propagation direction of the acoustic wave to achieve an excellent beam control effect.

[0079] Optionally, when the SAW resonator device is applied in the low frequency band, λ = 5.56um, H1 = 0.075λ, H2 = 0.11λ, h = 0.6H1. As Figure 3 The admittance and the real part of the admittance curve of the SAW resonator device in this embodiment at low frequency are shown. It can be seen from the figure that the real part of the admittance is smoother than that of the prior art, and the lateral mode is effectively suppressed during low frequency application.

[0080] Optionally, when the SAW resonator device is applied in the middle frequency band, λ = 2um, H1 = 0.085λ, H2 = 0.3λ, h = 0.7H1. As Figure 4The admittance and the real part curve of the admittance of the SAW resonator device of this embodiment at the intermediate frequency are shown. It can be seen from the figure that the real part of the admittance is smoother than that of the prior art, and the lateral mode can also be effectively suppressed during intermediate frequency applications.

[0081] Embodiment 2

[0082] As Figure 5 shown, the difference from Embodiment 1 is that the number of layers and the interlayer structure of the SAW resonator device are different.

[0083] As Figure 5 shown, the SAW resonator device of this embodiment is only provided with a substrate layer 25, a piezoelectric layer 22 and an electrode layer 21 connected in sequence, which reduces the difficulty of processing and forming while ensuring the performance of the SAW resonator device. Similarly, in this embodiment, the gap region and the bus bar are both located in the sinking region 10 for illustration.

[0084] Embodiment 3

[0085] As Figure 6 shown, the difference from Embodiment 1 is that the surface height of the electrode layer 21 is different.

[0086] As Figure 6 shown, the surface of the side of the electrode layer 21 away from the first interface is a plane, which is beneficial to providing a more uniform electric field distribution and simplifies the manufacturing process of the electrode layer 21 of the SAW resonator device.

[0087] Embodiment 4

[0088] As Figure 7 shown, the difference from Embodiment 1 is that the structure of the SAW resonator device is different.

[0089] As Figure 7 shown, the SAW resonator device further includes a dielectric layer 26. The contact of the acoustic wave at the interface between the electrode layer 21 and the air is reduced, thereby reducing the loss of the acoustic wave. At the same time, protection is provided for the electrode layer 21.

[0090] Embodiment 5

[0091] As Figure 8 shown, the difference from Embodiment 1 is that the interlayer structure of the SAW resonator device is different.

[0092] As Figure 8 shown, the SAW resonator device further includes a filling layer 27. The material of the filling layer 27 is different from that of the piezoelectric layer 22, providing a velocity barrier for the SAW resonator device. The ends of the fingers and the cross-sections of some of the piezoelectric layer 22 are air surfaces or the end surfaces of the filling layer 27, also forming discontinuous structural conditions to suppress the propagation of the lateral mode.

[0093] As can be seen from the above description, the above embodiments of the present utility model achieve the following technical effects:

[0094] 1. In the SAW resonator device, the electrode layer 21 is disposed on the first interface of the piezoelectric layer 22. Along the direction from the first interface to the second interface, the piezoelectric layer 22 has at least one etched sinking area 10. The electrode layer 21 can be disposed within the sinking area 10, or the filling layer 27 can be disposed first and then the electrode layer 21. All these are to form discontinuous structural conditions. The acoustic impedance of air and the material of the filling layer 27 is much larger than that of the material of the piezoelectric layer 22 and the metal material of the finger bars, increasing the discontinuity of the acoustic impedance, restricting the acoustic wave energy to the position without the sinking area 10 and preventing it from leaking to the outside continuously, thereby suppressing the lateral acoustic wave mode of the SAW resonator device.

[0095] 2. The SAW resonator device can process two spaced-apart sinking areas 10, such that the aperture area of the SAW resonator device corresponds to the unetched portion of the piezoelectric layer 22, which is located between the two sinking areas 10. Thus, the lateral acoustic wave mode is suppressed within the aperture area, further improving the Q value of the SAW resonator device.

[0096] Obviously, the above-described embodiments are only a part of the embodiments of the present utility model, rather than all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0097] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0098] It should be noted that the terms "first", "second", etc. in the description, claims, and drawings of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order different from those illustrated or described herein.

[0099] The above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. For those skilled in the art, the present utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A SAW resonator device, characterized in that, Comprising: Substrate layer (25); Piezoelectric layer (22), the piezoelectric layer (22) is disposed on one side of the substrate layer (25), the piezoelectric layer (22) has a second interface facing the substrate layer (25) and a first interface away from the substrate layer (25) relative to the second interface, the piezoelectric layer (22) has at least one sunken area (10) sunken in the direction from the first interface to the second interface; Electrode layer (21), the electrode layer (21) is disposed on the first interface, the electrode layer (21) has interdigital transducers and two oppositely disposed bus bars, the interdigital transducers include two sets of alternately distributed finger bars, one set of the finger bars is connected to one of the bus bars, a gap area is formed at the shortest distance between the end of the bus bar and the finger bar, and at least a part of the bus bar and at least a part of the gap area are located in the sunken area (10).

2. A SAW resonator device, characterized in that, Comprising: Substrate layer (25); Piezoelectric layer (22), the piezoelectric layer (22) is disposed on one side of the substrate layer (25), the piezoelectric layer (22) has a second interface facing the substrate layer (25) and a first interface away from the substrate layer (25) relative to the second interface, the piezoelectric layer (22) has at least one sunken area (10) sunken in the direction from the first interface to the second interface; Filling layer (27), the filling layer (27) is disposed in the sunken area (10), and the material of the filling layer (27) is different from that of the piezoelectric layer (22); Electrode layer (21), the electrode layer (21) is disposed on the first interface, the electrode layer (21) has interdigital transducers and two oppositely disposed bus bars, the interdigital transducers include two sets of alternately distributed finger bars, one set of the finger bars is connected to one of the bus bars, a gap area is formed at the shortest distance between the end of the bus bar and the finger bar, and the projections of at least a part of the bus bar and at least a part of the gap area on the first interface are located within the range of the sunken area (10).

3. The SAW resonator device according to claim 1 or 2, characterized in that, The depth h of the sunken area (10) and the minimum thickness H1 of the electrode layer (21) satisfy: 0 < h < H1.

4. The SAW resonator device according to claim 1 or 2, characterized in that, The minimum thickness H1 of the electrode layer (21) and the operating wavelength λ of the interdigital transducer satisfy: 0.05λ < H1 < 0.1λ.

5. The SAW resonator device according to claim 1 or 2, characterized in that, The maximum thickness H2 of the piezoelectric layer (22) and the operating wavelength λ of the interdigital transducer satisfy: 0.1λ < H2 < 0.5λ.

6. The SAW resonator device according to claim 1 or 2, characterized in that, The SAW resonator device has at least one side wall surface extending perpendicular to the substrate layer (25), and the sunken area (10) extends to the side wall surface.

7. The SAW resonator device according to claim 1 or 2, characterized in that, The piezoelectric layer (22) has two spaced-apart sunken areas (10), and the two sunken areas (10) are arranged in one-to-one correspondence with the two bus bars.

8. The SAW resonator device according to claim 1 or 2, wherein The surface of the electrode layer (21) away from the first interface is a plane; or The surface of the electrode layer (21) away from the first interface is shaped the same as the first interface.

9. The SAW resonator device according to claim 8, wherein The SAW resonator device further includes a dielectric layer (26), and the dielectric layer (26) is disposed on a surface of the electrode layer (21) on a side away from the first interface.

10. The SAW resonator device according to claim 2, characterized in that, At least one of the dielectric constant and the conductivity of the material of the filling layer (27) is different from that of the material of the piezoelectric layer (22).

11. The SAW resonator device according to claim 1 or 2, characterized in that, The SAW resonator device further includes a low acoustic velocity layer (23) and a high acoustic velocity layer (24), and the piezoelectric layer (22), the low acoustic velocity layer (23), the high acoustic velocity layer (24) and the substrate layer (25) are sequentially connected.

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