Surface acoustic wave resonance apparatus and forming method therefor

Abstract

A surface acoustic wave resonance apparatus and a forming method therefor. The structure of the surface acoustic wave resonance apparatus comprises: a bonding layer and a first load layer, which are located on a surface of a base, wherein the first load layer is located within the bonding layer, and the first load layer is parallel to a first direction; a piezoelectric layer, which is located on a surface of the bonding layer; and an interdigital electrode structure, which is located on a surface of the piezoelectric layer and comprises several first electrode strips and several second electrode strips, wherein each second electrode strip is located between two adjacent first electrode strips and partially overlaps with the adjacent first electrode strips, and the first electrode strips and the second electrode strips are all parallel to a second direction, which is parallel to the surface of the base and is perpendicular to the first direction. The base comprises an overlap region, wherein the overlapping parts of the several first electrode strips and the several second electrode strips are located in the overlap regions, the overlap region comprises end regions and a middle region, which are arranged in the second direction, the end regions are located on two sides of the middle region, and the first load layer is located on the end regions. The generation of transverse waves is effectively inhibited.

Description

Surface acoustic wave resonator device and method for forming the same

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 8, 2023, with application number 202310996062.1 and invention name “Surface Acoustic Wave Resonance Device and Formation Method Thereof”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the field of semiconductor technology, and in particular to a surface acoustic wave resonator device and a method for forming the same. Background Art

[0003] The radio frequency (RF) front-end chips for wireless communication devices include power amplifiers, antenna switches, RF filters, multiplexers, and low-noise amplifiers. RF filters include piezoelectric surface acoustic wave (SAW) filters, piezoelectric bulk acoustic wave (BAW) filters, micro-electro-mechanical system (MEMS) filters, and integrated passive device (IPD) filters.

[0004] Surface acoustic wave (SAW) resonators have a high quality factor (Q value). RF filters made from these devices exhibit low insertion loss and high out-of-band rejection. These SAW resonators are the mainstream RF filters currently used in wireless communication devices such as mobile phones and base stations.

[0005] However, the performance of existing surface acoustic wave resonator devices still needs to be improved.

[0006] Summary of the Invention

[0007] The technical problem solved by the present invention is to provide a surface acoustic wave resonator device and a forming method thereof, so as to improve the performance of a SAW filter.

[0008] To solve the above technical problems, the technical solution of the present invention provides a surface acoustic wave resonator device, comprising: a substrate; a bonding layer and a first load layer located on the surface of the substrate, the first load layer being located within the bonding layer, the first load layer being parallel to a first direction, and the first direction being parallel to the surface of the substrate; a piezoelectric layer being located on the surface of the bonding layer, the substrate and the piezoelectric layer being located on either side of the bonding layer; an interdigitated electrode structure being located on the surface of the piezoelectric layer, the interdigitated electrode structure comprising a plurality of first electrode strips and a plurality of second electrode strips, each second electrode strip being located between two adjacent first electrode strips and partially overlapping with adjacent first electrode strips, the first electrode strips and the second electrode strips being both parallel to a second direction, and the second direction being parallel to the surface of the substrate and perpendicular to the first direction; the substrate comprising an overlapping region, the overlapping portions of the plurality of first electrode strips and the plurality of second electrode strips being located on the overlapping region, the overlapping region comprising end regions and a middle region arranged along the second direction, the end regions being located on either side of the middle region, and the first load layer being located on the end regions.

[0009] Optionally, the substrate further includes a first bus region, a first gap region, a second gap region and a second bus region, the first bus region, the first gap region, the overlap region, the second gap region and the second bus region are arranged along the second direction, and the first gap region is located between the first bus region and the overlap region, and the second gap region is located between the second bus region and the overlap region; the interdigitated electrode structure further includes a first bus located on the first bus region and a second bus located on the second bus region, a number of the first electrode strips are located on the overlap region, extend to the first gap region, and are electrically connected to the first bus, and a number of the second electrode strips are located on the overlap region, extend to the second gap region, and are electrically connected to the second bus.

[0010] Optionally, the end region includes a first end region and a second end region, and the first end region and the second end region are respectively located on both sides of the middle region; the first load layer includes a first load portion located on the first end region and a second load portion located on the second end region; the first load portion and the second load portion have the same parameters, which include material, thickness and distance from the substrate surface.

[0011] Optionally, the end region includes a first end region and a second end region, and the first end region and the second end region are respectively located on both sides of the middle region; the first load layer is located on the first end region, and the bonding layer also includes a second load layer located on the second end region, and the second load layer is parallel to the first direction; the parameters of the first load layer and the second load layer are different, and the parameters include the distance between them and the surface of the substrate.

[0012] Optionally, the parameters further include one or more of material, width and thickness.

[0013] Optionally, the material of the second supporting layer includes metal, and the metal includes a combination of one or more of titanium, tungsten, molybdenum, platinum, gold and aluminum.

[0014] Optionally, it further includes: a temperature compensation layer located on the surface of the interdigital electrode structure, the temperature compensation layer covering the interdigital electrode structure; and the material of the temperature compensation layer includes silicon oxide.

[0015] Optionally, the material of the first supporting layer includes metal, and the metal includes a combination of one or more of titanium, tungsten, molybdenum, platinum, gold and aluminum.

[0016] Optionally, the bonding layer has a thickness ranging from 2000 angstroms to 10000 angstroms.

[0017] Optionally, the material of the piezoelectric layer includes a piezoelectric material, and the piezoelectric material includes lithium tantalate or lithium niobate.

[0018] Correspondingly, the technical solution of the present invention also provides a surface acoustic wave resonant device method, comprising: providing a substrate; forming a bonding layer and a first load layer located on the surface of the substrate, the first load layer being located in the bonding layer, the first load layer being parallel to a first direction, and the first direction being parallel to the surface of the substrate; obtaining a piezoelectric layer, bonding the substrate and the piezoelectric layer through the bonding layer, the substrate and the piezoelectric layer being located on both sides of the bonding layer; forming an interdigitated electrode structure located on the surface of the piezoelectric layer, the interdigitated electrode structure comprising a plurality of first electrode strips and a plurality of second electrode strips, each second electrode strip being located between two adjacent first electrode strips and partially overlapping with adjacent first electrode strips, the first electrode strips and the second electrode strips being parallel to a second direction, the second direction being parallel to the surface of the substrate and being perpendicular to the first direction; the substrate comprising an overlapping area, the overlapping portions of the plurality of first electrode strips and the plurality of second electrode strips being located on the overlapping area, the overlapping area comprising end areas and a middle area arranged along the second direction, the end areas being located on both sides of the middle area, and the first load layer being located on the end areas.

[0019] Optionally, the substrate further includes a first bus region, a first gap region, a second gap region and a second bus region, the first bus region, the first gap region, the overlap region, the second gap region and the second bus region are arranged along the second direction, and the first gap region is located between the first bus region and the overlap region, and the second gap region is located between the second bus region and the overlap region; the interdigitated electrode structure further includes a first bus located on the first bus region and a second bus located on the second bus region, a number of the first electrode strips are located on the overlap region, extend to the first gap region, and are electrically connected to the first bus, and a number of the second electrode strips are located on the overlap region, extend to the second gap region, and are electrically connected to the second bus.

[0020] Optionally, the end region includes a first end region and a second end region, and the first end region and the second end region are respectively located on both sides of the middle region; forming the first load layer includes forming a first load portion located on the first end region and a second load portion located on the second end region; the first load portion and the second load portion have the same parameters, and the parameters include material, thickness, and distance from the substrate surface.

[0021] Optionally, the method for forming the bonding layer and the first load layer includes: forming a first bonding material layer on the surface of the substrate; forming a first load material layer on the first bonding material layer; patterning the first load material layer to form the first load portion and the second load portion; forming a second bonding material layer on the surface of the first bonding material layer, the first load portion and the second load portion, covering the first bonding material layer, the first load portion and the second load portion.

[0022] Optionally, the end region includes a first end region and a second end region, the first end region and the second end region are respectively located on both sides of the middle region, the first load layer is located on the first end region, and further includes: forming a second load layer located on the second end region, the bonding layer also includes the second load layer, and the second load layer is parallel to the first direction; the parameters of the first load layer and the second load layer are different, and the parameters include the distance between them and the surface of the substrate.

[0023] Optionally, the parameters further include one or more of material, width and thickness.

[0024] Optionally, the method for forming the bonding layer, the first load layer and the second load layer includes: forming a first bonding material layer on the surface of the substrate; forming the first load layer on a portion of the surface of the first bonding material layer; forming a second bonding material layer on the surface of the first bonding material layer and the surface of the first load layer, the second bonding material layer covering the first bonding material layer and the first load layer; forming the second load layer on a portion of the surface of the second bonding material layer; forming a third bonding material layer on the surface of the second bonding material layer and the surface of the second load layer, the third bonding material layer covering the second bonding material layer and the second load layer.

[0025] Optionally, the method for forming the bonding layer, the first load layer and the second load layer includes: forming an initial first bonding material layer on the surface of the substrate; etching part of the initial first bonding material layer on the second end region so that the surface of the initial first bonding material layer on the second end region is lower than the surface of the initial first bonding material layer on the first end region to form a first bonding material layer; forming the first load layer located on the first end region and the second load layer located on the second end region on the first bonding material layer; forming a second bonding material layer on the surface of the first bonding material layer, the surface of the first load layer and the surface of the second load layer, the second bonding material layer covering the first bonding material layer, the first load layer and the second load layer.

[0026] Optionally, the method further includes: forming a temperature compensation layer on the surface of the interdigital electrode structure, wherein the temperature compensation layer covers the interdigital electrode structure; and the material of the temperature compensation layer includes silicon oxide.

[0027] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0028] In the surface acoustic wave resonator device provided by the technical solution of the present invention, a bonding layer and a first load layer are located on the surface of the substrate, and the first load layer is located within the bonding layer. The first load layer excites the surface acoustic wave resonator device to form a piston mode, suppresses high-order transverse parasitic resonances, and can effectively suppress the generation of transverse waves.

[0029] Furthermore, the bonding layer also includes a second load layer, and the parameters of the first load layer and the second load layer are different, and the parameters include the distance between the first load layer and the surface of the substrate; the parameters also include one or more of the material, width and thickness, so that the first load layer and the second load layer are differentiated, and the resonant frequencies of the first load layer and the second load layer can be adjusted respectively, so that the parasitic resonance introduced by the first load layer and the parasitic resonance introduced by the second load layer can offset or partially offset each other, thereby weakening the split mode caused by the introduction of the load structure.

[0030] In the method for forming a surface acoustic wave resonator device provided by the technical solution of the present invention, a bonding layer and a first load layer are formed on the surface of the substrate. The first load layer is located within the bonding layer. The first load layer excites the surface acoustic wave resonator device to form a piston mode, suppressing high-order transverse parasitic resonances, and effectively suppressing the generation of transverse waves.

[0031] Furthermore, the bonding layer also includes a second load layer, and the parameters of the first load layer and the second load layer are different, and the parameters include the distance between the first load layer and the surface of the substrate; the parameters also include one or more of the material, width and thickness, so that the first load layer and the second load layer are differentiated, and the resonant frequencies of the first load layer and the second load layer can be adjusted respectively, so that the parasitic resonance introduced by the first load layer and the parasitic resonance introduced by the second load layer can offset or partially offset each other, thereby weakening the split mode caused by the introduction of the load structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic structural diagram of a surface acoustic wave resonator device;

[0033] 2 to 17 are schematic structural diagrams of a formation process of a surface acoustic wave resonator device according to an embodiment of the present invention;

[0034] 18 is a schematic structural diagram of the formation process of a surface acoustic wave resonator device according to another embodiment of the present invention;

[0035] FIG. 19 is a structural diagram showing a process of forming a surface acoustic wave resonator device in another embodiment of the present invention. DETAILED DESCRIPTION

[0036] It should be noted that the terms “surface” and “on” in this specification are used to describe relative positional relationships in space and are not limited to whether there is direct contact.

[0037] As mentioned in the background art, the performance of surface acoustic wave resonator devices needs to be improved.

[0038] FIG1 is a schematic structural diagram of a surface acoustic wave resonator device.

[0039] 1 , the surface acoustic wave resonator device includes: a substrate 100 ; an intermediate layer 101 located on the substrate 100 ; a piezoelectric film 102 located on the intermediate layer 101 ; and an interdigitated electrode structure 103 located on the piezoelectric film 102 .

[0040] In the above-mentioned surface acoustic wave resonator device, the material of the substrate 100 is high-resistance silicon (Si), the material of the intermediate layer 101 is silicon oxide (SiO2), and the material of the piezoelectric film 102 is lithium tantalate (LiTaO3). The heterojunction in the heterostructure based on LiTaO3 / SiO2 / Si can effectively confine the energy of the high-speed acoustic wave mode in the piezoelectric film 102, thereby improving the frequency and Q value of the device; in addition, the substrate 100 with low thermal expansion coefficient and high thermal conductivity is also conducive to improving the temperature stability of the surface wave filter.

[0041] However, this structure has difficulty in suppressing high-order transverse parasitic modes, resulting in transverse waves in the filter passband, which increases insertion loss.

[0042] To address the above-mentioned issues, the technical solution of the present invention provides a surface acoustic wave resonator device and a method for forming the same, comprising a bonding layer and a first load layer located on the surface of the substrate, wherein the first load layer is located within the bonding layer. The first load layer excites the surface acoustic wave resonator device to form a piston mode, thereby suppressing high-order transverse parasitic resonances and effectively inhibiting the generation of transverse waves.

[0043] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] 2 to 18 are schematic structural diagrams of the formation process of the surface acoustic wave resonator device according to an embodiment of the present invention.

[0045] Please refer to Figures 2 and 3, Figure 2 is a schematic diagram of the top view structure of the substrate, and Figure 3 is a schematic diagram of the cross-sectional structure along the EE1 direction in Figure 2, providing a base 200, wherein the base 200 includes an overlapping area, and the overlapping area includes an end area and a middle area C arranged along the second direction Y, and the end area is located on both sides of the middle area C.

[0046] In this embodiment, the end region includes a first end region A and a second end region B, and the first end region A and the second end region B are located on both sides of the middle region C respectively.

[0047] In this embodiment, the substrate 200 is made of silicon; the resistivity of the substrate 200 ranges from 5000 Ω·cm to 10000 Ω·cm. The high resistivity of the substrate 200 is due to its low thermal expansion coefficient and high thermal conductivity. Using high-resistivity silicon in the substrate 200 can suppress deformation of the piezoelectric layer, thereby providing temperature compensation, achieving a lower frequency temperature drift coefficient, and improving device performance.

[0048] In this embodiment, the substrate 200 further includes a first bus area L1, a first gap area g1, a second gap area g2, and a second bus area L2. The first bus area L1, the first gap area g1, the overlapping area, the second gap area g2, and the second bus area L2 are arranged along the second direction Y, and the first gap area g1 is located between the first bus area L1 and the overlapping area, and the second gap area g2 is located between the second bus area L2 and the overlapping area.

[0049] Subsequently, a bonding layer and a first load layer are formed on the surface of the substrate 200. The first load layer is located in the bonding layer, parallel to a first direction X, parallel to the surface of the substrate 200, and located on the end region.

[0050] In this embodiment, forming the first load layer includes forming a first load portion located on the first end region A and a second load portion located on the second end region B. In another embodiment, the first load layer is located on the first end region, and a second load layer is further formed on the second end region. The second load layer is also located within the bonding layer and is parallel to the first direction.

[0051] In this embodiment, the first load portion and the second load portion have the same parameters, including material, thickness, and distance from the substrate surface. Specifically, the first load portion and the second load portion are located in the same layer.

[0052] In another embodiment, the first load layer and the second load layer have different parameters, wherein the parameters include the distance from the substrate surface. In yet another embodiment, the first load layer and the second load layer have different parameters, wherein the parameters also include one or more of material, width, and thickness.

[0053] In this embodiment, for the method of forming the bonding layer and the first supporting layer, please refer to FIG. 4 to FIG. 9 .

[0054] Please refer to Figures 4 to 6, Figure 4 is a schematic diagram of the top view structure, Figure 5 is a schematic diagram of the cross-sectional structure along the EE1 direction in Figure 4, and Figure 6 is a schematic diagram of the cross-sectional structure along the FF1 direction in Figure 4. A first bonding material layer 201 is formed on the surface of the substrate 200; the first load material layer (not shown in the figure) is formed on the first bonding material layer 201; the first load material layer is patterned to form the first load portion 202a and the second load portion 202b.

[0055] Specifically, the first load portion 202a is located on the first end region A, and the second load portion 202b is located on the second end region B; the first load portion 202a and the second load portion 202b are both parallel to the first direction X.

[0056] The material of the first support layer includes metal, and the metal includes one or more of titanium, tungsten, molybdenum, platinum, gold and aluminum. In this embodiment, the material of the first support layer is molybdenum.

[0057] Please refer to Figures 7 to 9, Figure 7 is a schematic diagram of the top view structure, Figure 8 is a schematic diagram of the cross-sectional structure along the EE1 direction in Figure 7, and Figure 9 is a schematic diagram of the cross-sectional structure along the FF1 direction in Figure 7. A second bonding material layer 203 is formed on the surface of the first bonding material layer 201, the first load part 202a and the second load part 202b, covering the first bonding material layer 201, the first load part 202a and the second load part 202b.

[0058] In this embodiment, the method for forming the bonding layer further includes: after forming the second bonding material layer 203, using a mechanochemical polishing process to planarize the surface of the second bonding material layer 203. The mechanochemical polishing process is used to ensure that the surface roughness (Ra) of the bonding layer meets bonding requirements and improve the bonding strength of the formed surface acoustic wave resonator device.

[0059] In this embodiment, the thickness of the bonding layer ranges from 2000 angstroms to 10000 angstroms.

[0060] The bonding layer material includes one or more of silicon oxide, silicon nitride, silicon, and gallium arsenide. Specifically, the first bonding material layer 201 and the second bonding material layer 203 include one or more of silicon oxide, silicon nitride, silicon, and gallium arsenide. When the bonding layer is made of a material with a positive frequency temperature coefficient (such as silicon oxide), it can compensate for the negative temperature coefficient of the piezoelectric layer, thereby achieving a lower frequency temperature drift coefficient and improving device stability.

[0061] In this embodiment, the first bonding material layer 201 and the second bonding material layer 203 are both made of silicon oxide.

[0062] Please refer to Figures 10 to 12, Figure 10 is a schematic diagram of the top view structure, Figure 11 is a schematic diagram of the cross-sectional structure along the EE1 direction in Figure 10, and Figure 12 is a schematic diagram of the cross-sectional structure along the FF1 direction in Figure 10, to obtain the piezoelectric layer 204, and to bond the substrate 200 and the piezoelectric layer 204 through the bonding layer, and the substrate 200 and the piezoelectric layer 204 are located on both sides of the bonding layer.

[0063] In this embodiment, after the bonding process, the piezoelectric layer 204 is thinned from the piezoelectric layer 204 toward the substrate 200 .

[0064] The material of the piezoelectric layer 204 includes a piezoelectric material, and the piezoelectric material includes lithium tantalate or lithium niobate. In this embodiment, the material of the piezoelectric layer 204 is lithium tantalate.

[0065] In this embodiment, the thinning process includes a mechanochemical grinding process.

[0066] Please refer to Figures 13 to 15, Figure 13 is a schematic diagram of the top view structure, Figure 14 is a schematic diagram of the cross-sectional structure along the EE1 direction in Figure 13, and Figure 15 is a schematic diagram of the cross-sectional structure along the FF1 direction in Figure 13, forming an interdigitated electrode structure located on the surface of the piezoelectric layer 204, the interdigitated electrode structure includes a plurality of first electrode strips 205 and a plurality of second electrode strips 206, each of the second electrode strips 206 is located between two adjacent first electrode strips 205, and partially overlaps with the adjacent first electrode strips 205, the overlapping parts of the plurality of first electrode strips 205 and the plurality of second electrode strips 206 are located on the overlapping area, the first electrode strips 205 and the second electrode strips 206 are both parallel to the second direction Y, the second direction Y is parallel to the surface of the substrate 200, and is perpendicular to the first direction X.

[0067] In this embodiment, the interdigitated electrode structure also includes a first bus 207 located on the first bus area L1 and a second bus 208 located on the second bus area L2. Several first electrode strips 205 are located on the overlapping area and extend to the first gap area g1 and are electrically connected to the first bus 207. Several second electrode strips 206 are located on the overlapping area and extend to the second gap area g2 and are electrically connected to the second bus 208.

[0068] The material of the interdigital electrode structure includes metal, and the metal includes one or more combinations of copper, aluminum, tungsten, cobalt, nickel, molybdenum, titanium and tantalum.

[0069] In this embodiment, a protective layer is further formed on the interdigital electrode structure. The method for forming the protective layer is shown in FIG16 and FIG17 .

[0070] In another embodiment, a temperature compensation layer is further formed on the interdigital electrode structure, and the temperature compensation layer covers the interdigital electrode structure; the material of the temperature compensation layer includes silicon oxide.

[0071] Please refer to FIG. 16 and FIG. 17 . The viewing direction of FIG. 16 is the same as that of FIG. 14 , and the viewing direction of FIG. 17 is the same as that of FIG. 15 . A protective layer 209 is formed on the interdigital electrode structure.

[0072] Thus, the first load layer excites the surface acoustic wave resonator to form a piston mode, suppresses high-order transverse parasitic resonance, and can effectively suppress the generation of transverse waves.

[0073] For ease of explanation, Figure 16 also shows a schematic diagram of the relative sound velocities corresponding to the various regions of the formed surface acoustic wave resonator device. Specifically, the first load portion 202a and the second load portion 202b are used to reduce the sound velocity within the surface acoustic wave resonator device regions at the first end region A and the second end region B, respectively, to a value lower than the sound velocity within the surface acoustic wave resonator device region at the intermediate region C, thereby forming a piston mode. In this embodiment, the first load portion 202a and the second load portion 202b have identical parameters, and therefore, the sound velocity within the surface acoustic wave resonator device regions at the first end region A and the second end region B is the same.

[0074] In this embodiment, the material of the protection layer 209 includes a dielectric material, and the dielectric material includes one or more of silicon nitride, silicon oxynitride, silicon oxycarbide, silicon carbonitride, and silicon carbon oxynitride.

[0075] Accordingly, an embodiment of the present invention further provides a surface acoustic wave resonator device formed by the above method, please continue to refer to Figures 16 and 17, comprising: a substrate 200; a bonding layer and a first load layer located on the surface of the substrate 200, the first load layer being located within the bonding layer, the first load layer being parallel to a first direction X, and the first direction X being parallel to the surface of the substrate; a piezoelectric layer 204 located on the surface of the bonding layer, the substrate 200 and the piezoelectric layer 204 being located on both sides of the bonding layer; an interdigitated electrode structure (as shown in Figure 13) located on the surface of the piezoelectric layer 204, the interdigitated electrode structure comprising a plurality of first electrode strips 205 and a plurality of second electrode strips 206. 06, each second electrode strip 206 is located between two adjacent first electrode strips 205 and partially overlaps with the adjacent first electrode strips 205, the first electrode strips 205 and the second electrode strips 206 are both parallel to the second direction Y, the second direction Y is parallel to the surface of the substrate 200 and is perpendicular to the first direction X; the substrate 200 includes an overlapping area, and the overlapping parts of several first electrode strips 205 and several second electrode strips 206 are located on the overlapping area, and the overlapping area includes end areas and a middle area C arranged along the second direction Y, the end areas are located on both sides of the middle area C, and the first load layer is located on the end areas.

[0076] In this embodiment, the substrate 200 further includes a first bus area L1, a first gap area g1, a second gap area g2, and a second bus area L2. The first bus area L1, the first gap area g1, the overlapping area, the second gap area g2, and the second bus area L2 are arranged along the second direction Y, and the first gap area g1 is located between the first bus area L1 and the overlapping area, and the second gap area g2 is located between the second bus area L2 and the overlapping area.

[0077] In this embodiment, the interdigitated electrode structure also includes a first bus 207 located on the first bus area L1 and a second bus 208 located on the second bus area L2. Several first electrode strips 205 are located on the overlapping area and extend to the first gap area g1 and are electrically connected to the first bus 207. Several second electrode strips 206 are located on the overlapping area and extend to the second gap area g2 and are electrically connected to the second bus 208.

[0078] In this embodiment, the end region includes a first end region A and a second end region B, and the first end region A and the second end region B are located on both sides of the middle region C respectively.

[0079] In this embodiment, the first load layer includes a first load portion 202a located on the first end region A and a second load portion 202b located on the second end region B. The first load portion 202a and the second load portion 202b have the same parameters, including the distance from the surface of the substrate 200. In this embodiment, the parameters also include one or more of material, width, and thickness.

[0080] In another embodiment, the end region includes a first end region and a second end region, and the first end region and the second end region are respectively located on both sides of the middle region; the first load layer is located on the first end region, and the bonding layer also includes a second load layer located on the second end region, and the second load layer is parallel to the first direction; the parameters of the first load layer and the second load layer are different, and the parameters include the distance between them and the surface of the substrate.

[0081] In this embodiment, the surface acoustic wave resonator device further includes: a protective layer 209 located on the interdigitated electrode structure; the material of the protective layer 209 includes a dielectric material, and the dielectric material includes one or more of silicon nitride, silicon oxynitride, silicon oxycarbide, silicon carbonitride and silicon carbon oxynitride.

[0082] In another embodiment, the surface acoustic wave resonator device further includes: a temperature compensation layer located on the interdigital electrode structure, the temperature compensation layer covering the interdigital electrode structure; and a material of the temperature compensation layer includes silicon oxide.

[0083] The material of the first support layer includes metal, and the metal includes one or more of titanium, tungsten, molybdenum, platinum, gold and aluminum. In this embodiment, the material of the first support layer is molybdenum.

[0084] In this embodiment, the substrate 200 is made of silicon; the resistivity of the substrate 200 ranges from 5000 Ω·cm to 10000 Ω·cm. The high resistivity of the substrate 200 is due to its low thermal expansion coefficient and high thermal conductivity. Using high-resistivity silicon in the substrate 200 can suppress the piezoelectric deformation of the piezoelectric layer, thereby providing temperature compensation, achieving a lower frequency temperature drift coefficient, and improving device stability.

[0085] The bonding layer is made of one or more materials selected from silicon oxide, silicon nitride, silicon, and gallium arsenide. When the bonding layer is made of a material with a positive frequency temperature coefficient (such as silicon oxide), it can compensate for the negative temperature coefficient of the piezoelectric layer, thereby achieving a lower frequency temperature drift coefficient and improving device stability.

[0086] In this embodiment, the material of the bonding layer is silicon oxide. Specifically, the material of the first bonding material layer 201 and the second bonding material layer 203 are both silicon oxide.

[0087] In this embodiment, the thickness of the bonding layer ranges from 2000 angstroms to 10000 angstroms.

[0088] The material of the piezoelectric layer 204 includes a piezoelectric material, and the piezoelectric material includes lithium tantalate or lithium niobate. In this embodiment, the material of the piezoelectric layer 204 is lithium tantalate.

[0089] FIG. 18 is a structural diagram illustrating a process of forming a surface acoustic wave resonator device according to another embodiment of the present invention.

[0090] The main difference between this embodiment and the previous embodiment is that: in the previous embodiment, the first load layer includes a first load part located on the first end area and a second load part located on the second end area; the parameters of the first load part and the second load part are the same; while in this embodiment, the first load layer is located on the first end area, and the bonding layer also includes a second load layer located on the second end area, and the second load layer is parallel to the first direction; the parameters of the first load layer and the second load layer are different, and the parameters include the distance between them and the surface of the substrate.

[0091] In this embodiment, the parameters further include one or more of material, width and thickness.

[0092] In this embodiment, for the method of forming the bonding layer, the first load layer and the second load layer, please refer to FIG18 based on FIG3 .

[0093] Please refer to Figure 18, a first bonding material layer 301 is formed on the surface of the substrate 200; the first load layer 302a is formed on a portion of the surface of the first bonding material layer 301; a second bonding material layer 303 is formed on the surface of the first bonding material layer 301 and the surface of the first load layer 302a, and the second bonding material layer 303 covers the first bonding material layer 301 and the first load layer 302a; a second load layer 302b is formed on a portion of the surface of the second bonding material layer 303; a third bonding material layer 304 is formed on the surface of the second bonding material layer 303 and the surface of the second load layer 302b, and the third bonding material layer 304 covers the second bonding material layer 303 and the second load layer 302b.

[0094] Here, the first load layer 302a and the second load layer 302b are located in different layers. The first load layer 302a and the second load layer 302b are different in one or more of material, width, and thickness. This differentiates the first load layer 302a and the second load layer 302b. The resonant frequencies of the first load layer 302a and the second load layer 302b can be adjusted separately, so that the parasitic resonance introduced by the first load layer 302a and the parasitic resonance introduced by the second load layer 302b can offset or partially offset each other, thereby reducing the split mode caused by the introduction of the load structure.

[0095] For ease of explanation, FIG18 also shows a schematic diagram of the relative magnitude of the sound speed corresponding to each region of the formed surface acoustic wave resonator device.

[0096] Specifically, the first load layer 302a and the second load layer 302b are used to reduce the sound speed in the surface acoustic wave resonator device area on the first end area A and the second end area B, respectively, so that the sound speed is lower than the sound speed in the surface acoustic wave resonator device area on the middle area C, thereby forming a piston mode.

[0097] In this embodiment, the mass of the second load layer 302b is greater than the mass of the first load layer 302a. Therefore, the sound velocity in the surface acoustic wave resonator region on the second end region B is lower than the sound velocity in the surface acoustic wave resonator region on the first end region A. The parasitic resonance introduced by the first load layer 302a is different from the parasitic resonance introduced by the second load layer 302b. The parasitic resonance can offset or partially offset each other, thereby reducing the split mode caused by the introduction of the load structure.

[0098] In this embodiment, the method for forming the bonding layer further includes: after forming the third bonding material layer 304 , performing a planarization process on the surface of the third bonding material layer 304 using a mechanical chemical polishing process.

[0099] Subsequently, please continue to refer to FIG18 , obtain a piezoelectric layer 305, bond the substrate 200 and the piezoelectric layer 305 through the bonding layer, the substrate 200 and the piezoelectric layer 305 are located on both sides of the bonding layer; form an interdigitated electrode structure 306 located on the surface of the piezoelectric layer 305, the interdigitated electrode structure 306 includes a plurality of first electrode strips (not shown in the figure) and a plurality of second electrode strips (not shown in the figure), each second electrode strip is located between two adjacent first electrode strips, and partially overlaps with the adjacent first electrode strips, the first electrode strips and the second electrode strips are both parallel to a second direction (not shown in the figure), the second direction is parallel to the surface of the substrate 200, and is perpendicular to the first direction (not shown in the figure); form a protective layer 307 on the interdigitated electrode structure 306. Here, please refer to the previous embodiment for a detailed description, which will not be repeated here.

[0100] Correspondingly, an embodiment of the present invention further provides a surface acoustic wave resonator device formed by the above method, please continue to refer to FIG18 .

[0101] The main difference between this embodiment and the previous embodiment is that: in the previous embodiment, the first load layer includes a first load portion located on the first end area and a second load portion located on the second end area; the parameters of the first load portion and the second load portion are the same; while in this embodiment, the first load layer 302a is located on the first end area A, and the bonding layer also includes a second load layer 302b located on the second end area B, and the second load layer 302b is parallel to the first direction; the parameters of the first load layer 302a and the second load layer 302b are different, and the parameters include the distance between them and the surface of the substrate 200.

[0102] In this embodiment, the parameters further include one or more of material, width and thickness.

[0103] FIG. 19 is a structural diagram showing a process of forming a surface acoustic wave resonator device in another embodiment of the present invention.

[0104] Please continue to refer to FIG19 based on FIG14 , and form a temperature compensation layer 400 on the interdigital electrode structure, and the temperature compensation layer 400 covers the interdigital electrode structure.

[0105] In this embodiment, the material of the temperature compensation layer 400 includes silicon oxide. Since silicon oxide is a material with a positive frequency temperature coefficient, the temperature compensation layer 400 can compensate for the negative temperature coefficient of the piezoelectric layer, thereby obtaining a lower frequency temperature drift coefficient and improving device performance.

[0106] The main difference between this embodiment and the previous embodiment is that in this embodiment, a temperature compensation layer 400 is formed on the interdigital electrode structure, while in the previous embodiment, a protective layer is formed on the interdigital electrode structure.

[0107] Correspondingly, an embodiment of the present invention further provides a surface acoustic wave resonator device formed by the above method, which includes a temperature compensation layer 400 located on the interdigital electrode structure, and further referring to FIG. 19 .

[0108] In this embodiment, the material of the temperature compensation layer 400 includes silicon oxide.

[0109] The main difference between this embodiment and the previous embodiment is that in this embodiment, a temperature compensation layer 400 is located on the interdigital electrode structure, while in the previous embodiment, a protective layer is formed on the interdigital electrode structure.

[0110] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A surface acoustic wave resonance device, characterized in that: include: substrate; A bonding layer and a first load layer located on the surface of the substrate, wherein the first load layer is located in the bonding layer, the first load layer is parallel to a first direction, and the first direction is parallel to the surface of the substrate; A piezoelectric layer is located on the surface of the bonding layer, and the substrate and the piezoelectric layer are located on both sides of the bonding layer; an interdigitated electrode structure located on the surface of the piezoelectric layer, the interdigitated electrode structure comprising a plurality of first electrode strips and a plurality of second electrode strips, each of the second electrode strips being located between two adjacent first electrode strips and partially overlapping with adjacent first electrode strips, the first electrode strips and the second electrode strips being parallel to a second direction, the second direction being parallel to the substrate surface and perpendicular to the first direction; The substrate includes an overlapping area, and the overlapping parts of the first electrode strips and the second electrode strips are located on the overlapping area. The overlapping area includes end areas and a middle area arranged along the second direction, the end areas are located on both sides of the middle area, and the first load layer is located on the end areas.

2. The surface acoustic wave resonator device according to claim 1, characterized in that: The substrate also includes a first bus area, a first gap area, a second gap area and a second bus area, the first bus area, the first gap area, the overlap area, the second gap area and the second bus area are arranged along the second direction, and the first gap area is located between the first bus area and the overlap area, and the second gap area is located between the second bus area and the overlap area; the interdigitated electrode structure also includes a first bus located on the first bus area and a second bus located on the second bus area, a number of the first electrode strips are located on the overlap area, extend to the first gap area, and are electrically connected to the first bus, and a number of the second electrode strips are located on the overlap area, extend to the second gap area, and are electrically connected to the second bus.

3. The surface acoustic wave resonator device according to claim 1, characterized in that: The end region includes a first end region and a second end region, and the first end region and the second end region are respectively located on both sides of the middle region; the first load layer includes a first load portion located on the first end region and a second load portion located on the second end region; the first load portion and the second load portion have the same parameters, and the parameters include material, thickness and distance from the surface of the substrate.

4. The surface acoustic wave resonator device according to claim 1, characterized in that: The end region includes a first end region and a second end region, the first end region and the second end region are respectively located on both sides of the middle region; the first load layer is located on the first end region, and the bonding layer also includes a second load layer located on the second end region, and the second load layer is parallel to the first direction; the first load layer and the second load layer have different parameters, and the parameters include the distance between them and the surface of the substrate.

5. The surface acoustic wave resonator device according to claim 4, characterized in that: The parameters also include one or more of material, width, and thickness.

6. The surface acoustic wave resonator device according to claim 4, characterized in that: The material of the second support layer includes a metal, and the metal includes a combination of one or more of titanium, tungsten, molybdenum, platinum, gold and aluminum.

7. The surface acoustic wave resonator device according to claim 1, characterized in that: Also includes: A temperature compensation layer located on the surface of the interdigital electrode structure, wherein the temperature compensation layer covers the interdigital electrode structure; The material of the temperature compensation layer includes silicon oxide.

8. The surface acoustic wave resonator device according to claim 1, characterized in that: The material of the first support layer includes a metal, and the metal includes a combination of one or more of titanium, tungsten, molybdenum, platinum, gold and aluminum.

9. The surface acoustic wave resonator device according to claim 1, characterized in that: The bonding layer has a thickness ranging from 2000 angstroms to 10000 angstroms.

10. The surface acoustic wave resonator device according to claim 1, characterized in that: The material of the piezoelectric layer includes a piezoelectric material, and the piezoelectric material includes lithium tantalate or lithium niobate.

11. A method for forming a surface acoustic wave resonator device, characterized in that: include: providing a substrate; Forming a bonding layer and a first load layer on the surface of the substrate, wherein the first load layer is located in the bonding layer, the first load layer is parallel to a first direction, and the first direction is parallel to the surface of the substrate; Acquire a piezoelectric layer, and bond the substrate and the piezoelectric layer via the bonding layer, wherein the substrate and the piezoelectric layer are located on both sides of the bonding layer; forming an interdigitated electrode structure located on the surface of the piezoelectric layer, wherein the interdigitated electrode structure includes a plurality of first electrode strips and a plurality of second electrode strips, wherein each of the second electrode strips is located between two adjacent first electrode strips and partially overlaps with an adjacent first electrode strip, and the first electrode strips and the second electrode strips are both parallel to a second direction, and the second direction is parallel to the substrate surface and perpendicular to the first direction; The substrate includes an overlapping area, and the overlapping parts of the first electrode strips and the second electrode strips are located on the overlapping area. The overlapping area includes end areas and a middle area arranged along the second direction, the end areas are located on both sides of the middle area, and the first load layer is located on the end areas.

12. The method for forming a surface acoustic wave resonator device according to claim 11, wherein: The substrate also includes a first bus area, a first gap area, a second gap area and a second bus area, the first bus area, the first gap area, the overlap area, the second gap area and the second bus area are arranged along the second direction, and the first gap area is located between the first bus area and the overlap area, and the second gap area is located between the second bus area and the overlap area; the interdigitated electrode structure also includes a first bus located on the first bus area and a second bus located on the second bus area, a number of the first electrode strips are located on the overlap area, extend to the first gap area, and are electrically connected to the first bus, and a number of the second electrode strips are located on the overlap area, extend to the second gap area, and are electrically connected to the second bus.

13. The method for forming a surface acoustic wave resonator device according to claim 11, wherein: The end region includes a first end region and a second end region, and the first end region and the second end region are respectively located on both sides of the middle region; forming the first load layer includes forming a first load portion located on the first end region and a second load portion located on the second end region; the first load portion and the second load portion have the same parameters, and the parameters include material, thickness, and distance from the surface of the substrate.

14. The method for forming a surface acoustic wave resonator device according to claim 13, wherein: The method for forming the bonding layer and the first load layer includes: forming a first bonding material layer on the surface of the substrate; forming a first load material layer on the first bonding material layer; patterning the first load material layer to form the first load part and the second load part; forming a second bonding material layer on the surface of the first bonding material layer, the first load part and the second load part, covering the first bonding material layer, the first load part and the second load part.

15. The method for forming a surface acoustic wave resonator device according to claim 11, wherein: The end region includes a first end region and a second end region, the first end region and the second end region are respectively located on both sides of the middle region, the first load layer is located on the first end region, and further includes: forming a second load layer located on the second end region, the bonding layer also includes the second load layer, the second load layer is parallel to the first direction; the first load layer and the second load layer have different parameters, and the parameters include the distance between the first load layer and the substrate surface.

16. The method for forming a surface acoustic wave resonator device according to claim 15, wherein: The parameters also include one or more of material, width, and thickness.

17. The method for forming a surface acoustic wave resonator device according to claim 15, wherein: The method for forming the bonding layer, the first load layer and the second load layer includes: forming a first bonding material layer on the surface of the substrate; forming the first load layer on a portion of the surface of the first bonding material layer; forming a second bonding material layer on the surface of the first bonding material layer and the surface of the first load layer, the second bonding material layer covering the first bonding material layer and the first load layer; forming the second load layer on a portion of the surface of the second bonding material layer; forming a third bonding material layer on the surface of the second bonding material layer and the surface of the second load layer, the third bonding material layer covering the second bonding material layer and the second load layer.

18. The method for forming a surface acoustic wave resonator device according to claim 15, wherein: The method for forming the bonding layer, the first load layer and the second load layer includes: forming an initial first bonding material layer on the surface of the substrate; etching part of the initial first bonding material layer on the second end region so that the surface of the initial first bonding material layer on the second end region is lower than the surface of the initial first bonding material layer on the first end region to form a first bonding material layer; forming the first load layer located on the first end region and the second load layer located on the second end region on the first bonding material layer; forming a second bonding material layer on the surface of the first bonding material layer, the surface of the first load layer and the surface of the second load layer, the second bonding material layer covering the first bonding material layer, the first load layer and the second load layer.

19. The method for forming a surface acoustic wave resonator device according to claim 11, wherein: Also includes: forming a temperature compensation layer on the surface of the interdigital electrode structure, wherein the temperature compensation layer covers the interdigital electrode structure; The material of the temperature compensation layer includes silicon oxide.

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