Method for forming surface acoustic wave resonance device

Abstract

A forming method of a surface acoustic wave resonance device comprises the steps that an interdigital electrode structure is formed on the surface of a piezoelectric layer, and the interdigital electrode structure comprises a plurality of first electrode strips and a plurality of second electrode strips; a temperature compensation layer is formed on the piezoelectric layer, the temperature compensation layer covers the interdigital electrode structure, the temperature compensation layer comprises a first temperature compensation material layer, and the forming method of the temperature compensation layer comprises the following steps: forming the first temperature compensation material layer on the piezoelectric layer and the interdigital electrode structure by adopting a plasma enhanced chemical vapor deposition process, according to the plasma enhanced chemical vapor deposition process, tetraethoxysilane is adopted as a reaction source, the plasma enhanced chemical vapor deposition process has a first process temperature, and the first process temperature ranges from 270 DEG C to 400 DEG C, so that the uniformity and compactness of the temperature compensation layer are improved, the temperature coefficient of frequency (TCF) of the surface acoustic wave resonance device is improved, and the surface acoustic wave resonance effect is improved. And the working stability and reliability of the surface acoustic wave resonance device are improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for forming a surface acoustic wave resonance device. Background Art

[0002] The RF (Radio Frequency, referred to as RF) front-end chips of wireless communication equipment include power amplifiers, antenna switches, RF filters, multiplexers and low noise amplifiers, etc. Among them, RF filters include piezoelectric surface acoustic wave (Surface Acoustic Wave, referred to as SAW) filters, piezoelectric bulk acoustic wave (Bulk Acoustic Wave, referred to as BAW) filters, micro-electro-mechanical system (Micro-Electro-Mechanical System, referred to as MEMS) filters, integrated passive devices (Integrated Passive Devices, referred to as IPD) filters, etc.

[0003] The quality factor (Q value) of the surface acoustic wave resonator is relatively high. The RF filter made of the surface acoustic wave resonator has low insertion loss and high out-of-band rejection. That is, the surface acoustic wave resonator is the mainstream RF filter used in wireless communication devices such as mobile phones and base stations.

[0004] However, the performance of existing surface acoustic wave resonator devices needs to be improved. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for forming a surface acoustic wave resonant device to improve the performance of a SAW filter.

[0006] In order to solve the above technical problems, the technical solution of the present invention provides a method for forming a surface acoustic wave resonance device, including: providing a substrate; forming an intermediate layer, bonding the substrate and the piezoelectric layer through the intermediate layer, and the substrate and the piezoelectric layer are located on both sides of the intermediate layer; forming an interdigitated electrode structure on the surface of the piezoelectric layer, the interdigitated electrode structure including a plurality of first electrode strips and a plurality of second electrode strips, the first electrode strips and the second electrode strips are both parallel to the first direction and arranged at intervals along the second direction; forming a temperature compensation layer on the piezoelectric layer, the temperature compensation layer covering the interdigitated electrode structure, the temperature compensation layer including a first temperature compensation material layer, and the method for forming the temperature compensation layer includes: using a plasma enhanced chemical vapor deposition process to form the first temperature compensation material layer on the piezoelectric layer and the interdigitated electrode structure, the plasma enhanced chemical vapor deposition process using tetraethyl orthosilicate as a reaction source, the plasma enhanced chemical vapor deposition process having a first process temperature, and the first process temperature ranges from 270°C to 400°C.

[0007] Optionally, the process parameters of the plasma enhanced chemical vapor deposition process also include: a radio frequency power range of 600W to 800W, and a chamber pressure range of 0.6Torr to 0.8Torr.

[0008] Optionally, the plasma enhanced chemical vapor deposition process has a first deposition rate, and the first deposition rate is in the range of to

[0009] Optionally, the temperature compensation layer also includes a second temperature compensation material layer, and the method for forming the temperature compensation layer also includes: before forming the first temperature compensation material layer, using a physical vapor deposition process to form the second temperature compensation material layer on the piezoelectric layer, the second temperature compensation material layer at least covers the gap between the first electrode strip and the second electrode, and the first temperature compensation material layer is formed on the surface of the second temperature compensation material layer.

[0010] Optionally, the physical vapor deposition process has a second deposition rate, and the range of the second deposition rate is to

[0011] Optionally, the interdigitated electrode structure has a first thickness, the second temperature compensation material layer has a second thickness, and a ratio of the second thickness to the first thickness ranges from 1:2 to 2:1.

[0012] Optionally, the first thickness ranges from to The second thickness range is to

[0013] Optionally, the physical vapor deposition process includes a sputtering coating process, and the sputtering coating process has a second process temperature. The process parameters of the sputtering coating process include: the second process temperature ranges from 70°C to 80°C, the chamber gas pressure ranges from 950Torr to 1050Torr, and the RF power ranges from 290W to 310W.

[0014] Optionally, the interdigitated electrode structure has a first thickness, the first temperature compensation material layer has a third thickness, and a ratio of the third thickness to the first thickness ranges from 1:1 to 5:1.

[0015] Optionally, the third thickness ranges from 0.5 μm to 1 μm.

[0016] Optionally, the material of the temperature compensation layer includes silicon dioxide, silicon oxyfluoride, silicon oxynitride, or silicon oxycarbide.

[0017] Optionally, the interdigitated electrode structure has a first thickness, adjacent first electrode strips and second electrode strips have a first spacing, and a ratio of the first thickness to the first spacing ranges from 2:1 to 30:1.

[0018] Optionally, the method further includes: performing planarization processing on the first temperature compensation material layer.

[0019] Optionally, the material of the substrate includes silicon or silicon carbide.

[0020] Optionally, it also includes: forming a trap-rich layer on the surface of the substrate, the trap-rich layer is located between the intermediate layer and the substrate; the material of the trap-rich layer includes polysilicon; the formation process of the trap-rich layer includes a normal pressure chemical vapor deposition process or a low pressure chemical vapor deposition process.

[0021] Optionally, the material of the intermediate layer includes a dielectric material, and the dielectric material includes one or more of silicon dioxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon oxyfluoride, silicon carbonitride and silicon carbon oxynitride.

[0022] Optionally, the intermediate layer is formed on the substrate; a method for forming the intermediate layer includes a plasma enhanced chemical vapor deposition process or a physical vapor deposition process.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] In the method for forming a surface acoustic wave resonator device provided by the technical solution of the present invention, a substrate and a piezoelectric layer are joined by an intermediate layer, an interdigitated electrode structure is formed on the surface of the piezoelectric layer, a temperature compensation layer is formed on the piezoelectric layer and the interdigitated electrode structure, the temperature compensation layer covers the interdigitated electrode structure, the temperature compensation layer includes a first temperature compensation material layer, and the method for forming the first temperature compensation material layer includes: using a plasma enhanced chemical vapor deposition process to form a first temperature compensation material layer on the piezoelectric layer and the interdigitated electrode structure. Since a substrate material with higher heat dissipation performance (such as a silicon substrate) can be selected, under the premise of having little adverse effect on the temperature of the piezoelectric layer, a plasma enhanced chemical vapor deposition process with a first process temperature range of 270°C to 400°C is used to form the first temperature compensation material layer, thereby obtaining a higher deposition rate and reducing the process time; the plasma enhanced chemical vapor deposition process uses tetraethyl orthosilicate as a reaction source, which is beneficial to improving the uniformity and density of the first temperature compensation material layer, and is beneficial to improving the quality of the temperature compensation layer as a whole, thereby improving the temperature coefficient of frequency (TCF) of the surface acoustic wave resonance device, and improving the stability and reliability of the surface acoustic wave resonance device; in addition, silicon material can be used as the substrate material. Since silicon has a lower thermal expansion coefficient, it can effectively inhibit the thermal expansion of the piezoelectric layer and reduce the cracking rate. At the same time, the silicon material has a higher heat dissipation performance and can improve the power tolerance of the device.

[0025] Furthermore, a physical vapor deposition process is used to form a second temperature compensation material layer on the surface of the piezoelectric layer and the surface of the interdigitated electrode structure, and a first temperature compensation material layer is formed on the surface of the second temperature compensation material layer. The physical vapor deposition process is beneficial to improving the filling capacity of the second temperature compensation material layer in the interdigitated electrode structure, reducing the generation of voids, improving the density of the second temperature compensation material layer, and further improving the quality of the formed temperature compensation layer, thereby improving the temperature coefficient of frequency (TCF) of the surface acoustic wave resonant device and improving the stability and reliability of the operation of the surface acoustic wave resonant device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of a surface acoustic wave resonance device;

[0027] Figure 2 is a schematic flow chart of a method for forming a surface acoustic wave resonator device in one embodiment of the present invention;

[0028] Figures 3 to 6 is a structural schematic diagram of a formation process of a surface acoustic wave resonator device in one embodiment of the present invention;

[0029] Figures 7 to 9 It is a structural schematic diagram of the formation process of a surface acoustic wave resonance device in another embodiment of the present invention. DETAILED DESCRIPTION

[0030] 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 direct contact.

[0031] As described in the background art, the performance of the surface acoustic wave resonance device needs to be improved. Now, a surface acoustic wave resonance device is described and analyzed.

[0032] Figure 1 It is a structural schematic diagram of a surface acoustic wave resonance device.

[0033] Please refer to Figure 1 The surface acoustic wave resonance device includes: a piezoelectric substrate 100; an interdigital electrode structure 101 located on the piezoelectric substrate 100; and a temperature compensation layer 102 located on the interdigital electrode structure 101.

[0034] In the above-mentioned surface acoustic wave resonator device, the piezoelectric substrate 100 is a lithium niobate (LiNbO3, abbreviated as LN) substrate with a surface tangent of 128 degrees, and the material of the temperature compensation layer 102 is silicon dioxide (SiO2). The silicon dioxide material with a positive temperature coefficient of frequency (TCF) can compensate the piezoelectric substrate 100 with a negative temperature coefficient of frequency, which is conducive to obtaining a temperature coefficient of frequency tending to zero and improving the stability of the device.

[0035] However, the crystal structure characteristics of lithium niobate material determine that it has poor stability at high temperatures, which will lead to instability and deformation of the crystal structure at high temperatures, and then lead to an increase in the fragmentation rate during the online production process. Therefore, the process temperature of the temperature compensation layer 102 is limited. At present, the temperature compensation layer 102 can only be deposited on the surface of the piezoelectric substrate 100 by using a physical vapor deposition (PVD) process with a relatively low process temperature (usually less than 300°C) by bombarding the source material with high-frequency plasma to reduce the adverse effects of temperature on the piezoelectric substrate 100. However, the deposition rate of the physical vapor deposition process is slow, and the formed temperature compensation layer 102 has poor adhesion and poor thickness uniformity, which affects the performance of the surface acoustic wave resonance device.

[0036] In order to solve the above problems, the technical solution of the present invention provides a method for forming a surface acoustic wave resonator device, in which a substrate and a piezoelectric layer are joined by an intermediate layer, an interdigitated electrode structure is formed on the surface of the piezoelectric layer, and a temperature compensation layer is formed on the piezoelectric layer and the interdigitated electrode structure, the temperature compensation layer covers the interdigitated electrode structure, the temperature compensation layer includes a first temperature compensation material layer, and the method for forming the first temperature compensation material layer includes: using a plasma enhanced chemical vapor deposition process to form a first temperature compensation material layer on the piezoelectric layer and the interdigitated electrode structure. Since a substrate material with higher heat dissipation performance (such as a silicon substrate) can be selected, under the premise of having little adverse effect on the temperature of the piezoelectric layer, a plasma enhanced chemical vapor deposition process with a first process temperature range of 270°C to 400°C is used to form the first temperature compensation material layer, thereby obtaining a higher deposition rate and reducing the process time; the plasma enhanced chemical vapor deposition process uses tetraethyl orthosilicate as a reaction source, which is beneficial to improving the uniformity and density of the first temperature compensation material layer, and is beneficial to improving the quality of the temperature compensation layer as a whole, and further helps to improve the temperature coefficient of frequency (TCF) of the surface acoustic wave resonance device, and improve the stability and reliability of the operation of the surface acoustic wave resonance device; in addition, silicon material can be used as the substrate material. Since silicon has a lower thermal expansion coefficient, it can effectively inhibit the thermal expansion of the piezoelectric layer and reduce the cracking rate. At the same time, the silicon material has a higher heat dissipation performance, which can improve the power tolerance of the device.

[0037] 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.

[0038] Figure 2 It is a schematic flow chart of a method for forming a surface acoustic wave resonator device in one embodiment of the present invention.

[0039] Please refer to Figure 2 , the method for forming the surface acoustic wave resonator device comprises the following steps:

[0040] Step S21, providing a substrate;

[0041] Step S22, forming an intermediate layer, bonding the substrate and the piezoelectric layer through the intermediate layer, wherein the substrate and the piezoelectric layer are located on both sides of the intermediate layer;

[0042] Step S23, forming an interdigitated electrode structure 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 the first electrode strips and the second electrode strips are parallel to the first direction and are arranged at intervals along the second direction;

[0043] Step S24, forming a temperature compensation layer on the piezoelectric layer and the interdigitated electrode structure, the temperature compensation layer covering the interdigitated electrode structure, the temperature compensation layer including a first temperature compensation material layer, and the method for forming the temperature compensation layer comprising: using a plasma enhanced chemical vapor deposition process to form a first temperature compensation material layer on the piezoelectric layer and the interdigitated electrode structure, the plasma enhanced chemical vapor deposition process using tetraethyl orthosilicate as a reaction source, the plasma enhanced chemical vapor deposition process having a first process temperature, and the first process temperature ranges from 270°C to 400°C.

[0044] The following is a detailed description with reference to the accompanying drawings.

[0045] Figures 3 to 6 It is a structural schematic diagram of the formation process of a surface acoustic wave resonance device in one embodiment of the present invention.

[0046] Execute step S21, please refer to Figure 3 , providing a substrate 200.

[0047] In this embodiment, the thermal conductivity of the substrate 200 is greater than the thermal conductivity of the piezoelectric layer, and the thermal expansion coefficient of the substrate 200 is less than the thermal expansion coefficient of the piezoelectric layer.

[0048] In this embodiment, the material of the substrate 200 includes silicon; the resistivity of the substrate 200 is greater than 2000Ω·cm. The resistivity of the substrate 200 is relatively high. Since high-resistance silicon has the characteristics of low thermal expansion coefficient and high thermal conductivity, its use in the substrate 200 can suppress the deformation of the piezoelectric layer, reduce the cracking rate, and improve the temperature coefficient of frequency (TCF) of the device; in addition, the substrate 200 has a high heat dissipation performance, which can improve the power tolerance of the device. At the same time, when the temperature compensation layer is subsequently formed, the adverse effect of the process temperature on the piezoelectric layer can be reduced.

[0049] In another embodiment, the material of the substrate may be silicon carbide.

[0050] Execute step S22, please refer to Figure 4 , forming an intermediate layer 201 , through which the substrate 200 and the piezoelectric layer 203 are bonded, and the substrate 200 and the piezoelectric layer 203 are located on both sides of the intermediate layer 201 .

[0051] In this embodiment, a trap-rich layer 202 is further formed on the surface of the substrate 200, and the trap-rich layer 202 is located between the intermediate layer 201 and the substrate 200. The trap-rich layer 202 is used to reduce the parasitic surface conductance effect at the interface between the substrate 200 and the intermediate layer 201, reduce electrical loss, and improve the Q value or electromechanical coupling coefficient (Kt) of the surface acoustic wave resonator.

[0052] In this embodiment, the material of the trap-rich layer 202 includes polysilicon.

[0053] The process for forming the trap-rich layer 202 includes a normal pressure chemical vapor deposition process or a low pressure chemical vapor deposition process. In this embodiment, the process for forming the trap-rich layer 202 includes a normal pressure chemical vapor deposition process.

[0054] In this embodiment, the intermediate layer 201 is formed on the substrate 200 , and the piezoelectric layer 203 and the intermediate layer 201 are bonded.

[0055] In another embodiment, the intermediate layer is formed on one side of the piezoelectric layer, and the intermediate layer and the substrate are bonded.

[0056] In another embodiment, a first bonding layer is formed on the substrate, a second bonding layer is formed on one side of the piezoelectric layer, the first bonding layer and the second bonding layer are bonded, and the first bonding layer and the second bonding layer form the intermediate layer.

[0057] The intermediate layer 201 is formed by a plasma enhanced chemical vapor deposition process or a physical vapor deposition process.

[0058] In this embodiment, the intermediate layer 201 is formed by a plasma enhanced chemical vapor deposition process.

[0059] The material of the intermediate layer 201 includes a dielectric material, and the dielectric material includes one or more of silicon dioxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon oxyfluoride, silicon carbonitride and silicon carbon oxynitride. In this embodiment, the material of the intermediate layer 201 is silicon dioxide.

[0060] The material of the piezoelectric layer 203 includes a piezoelectric material, and the piezoelectric material includes lithium tantalate or lithium niobate. In this embodiment, the material of the piezoelectric layer 203 is lithium niobate.

[0061] In this embodiment, the method for bonding the substrate 200 and the piezoelectric layer 203 through the intermediate layer 201 includes: obtaining an initial piezoelectric layer (not shown in the figure); bonding the substrate 200 and the initial piezoelectric layer through the intermediate layer 201; and processing the initial piezoelectric layer using a smart-cut process to form the piezoelectric layer 203.

[0062] In another embodiment, the method of joining the substrate and the piezoelectric layer through the intermediate layer includes: obtaining an initial piezoelectric layer (not shown in the figure); joining the substrate and the initial piezoelectric layer through the intermediate layer; and thinning the initial piezoelectric layer using a grinding and polishing process to form the piezoelectric layer.

[0063] Execute step S23, please refer to Figure 5 A forked electrode structure 204 is formed on the surface of the piezoelectric layer 203, and the forked electrode structure 204 includes a plurality of first electrode strips 204a and a plurality of second electrode strips 204b. The first electrode strips 204a and the second electrode strips 204b are parallel to a first direction (not shown in the figure) and are arranged at intervals along a second direction (not shown in the figure).

[0064] The interdigitated electrode structure 204 has a first thickness, and the first thickness ranges from to In this embodiment, the first thickness is

[0065] In this embodiment, there is a first spacing between adjacent first electrode strips 204a and second electrode strips 204b, and the ratio of the first thickness to the first spacing is in a range of 2:1 to 30:1. There is a gap between the first electrode strips 204a and the second electrode strips 204b, and the ratio of the first thickness to the first spacing is the aspect ratio of the gap.

[0066] In this embodiment, the interdigitated electrode structure 204 also includes a first bus (not shown in the figure) and a second bus (not shown in the figure) arranged along the first direction, the first bus is connected to a plurality of first electrode strips 204a, and the second bus is connected to a plurality of second electrode strips 204b.

[0067] It should be noted that the thickness described herein refers to the dimension in a direction perpendicular to the surface of the substrate 200 .

[0068] The material of the interdigital electrode structure 204 includes metal, and the metal includes one or more combinations of copper, aluminum, tungsten, cobalt, nickel, molybdenum, titanium and tantalum.

[0069] Execute step S24, please refer to Figure 6 A temperature compensation layer is formed on the piezoelectric layer 203 and the interdigitated electrode structure 204, and the temperature compensation layer covers the interdigitated electrode structure 204. The temperature compensation layer includes a first temperature compensation material layer 205. The method for forming the first temperature compensation material layer 205 includes: using a plasma enhanced chemical vapor deposition process to form the first temperature compensation material layer 205 on the piezoelectric layer 203 and the interdigitated electrode structure 204. The plasma enhanced chemical vapor deposition process uses tetraethyl orthosilicate as a reaction source. The plasma enhanced chemical vapor deposition process has a first process temperature, and the first process temperature ranges from 270°C to 400°C.

[0070] Here, since a substrate material with higher heat dissipation performance (such as a silicon substrate) can be selected, under the premise that the adverse temperature effect on the piezoelectric layer 203 is small, a plasma enhanced chemical vapor deposition process with a first process temperature range of 270°C to 400°C is used to form the first temperature compensation material layer 205, thereby obtaining a higher deposition rate and reducing the process time; the plasma enhanced chemical vapor deposition process uses tetraethyl orthosilicate as a reaction source, which is beneficial to improving the uniformity and density of the first temperature compensation material layer 205, and is beneficial to improving the quality of the temperature compensation layer as a whole, and further helps to improve the temperature coefficient of frequency (TCF) of the surface acoustic wave resonance device, and improve the stability and reliability of the surface acoustic wave resonance device; in addition, silicon material can be used as the substrate material. Since silicon has a lower thermal expansion coefficient, it can effectively suppress the thermal expansion of the piezoelectric layer and reduce the cracking rate. At the same time, the silicon material has a higher heat dissipation performance, which can improve the power tolerance of the device.

[0071] Here, it should be noted that, compared with the temperature compensation layer formed by the physical vapor deposition process, the thickness uniformity of the temperature compensation layer formed in this embodiment is optimized from 3.56% to 0.98%, which is beneficial to improve the frequency consistency of the surface acoustic wave resonator. In addition, the stress of the temperature compensation layer is reduced from -1200N / mm 2 Reduced to -48N / mm 2 , which can prevent the temperature compensation layer from cracking and deformation, and reduce the probability of abnormal cracking of the surface acoustic wave resonator device, and significantly improve the performance.

[0072] The material of the temperature compensation layer includes silicon dioxide, silicon oxyfluoride, silicon oxynitride, and silicon oxycarbide.

[0073] In this embodiment, the material of the first temperature compensation material layer 205 includes silicon dioxide.

[0074] In this embodiment, the first temperature compensation material layer 205 is further planarized to make the surface of the obtained temperature compensation layer relatively flat.

[0075] The planarization method includes a chemical mechanical polishing (CMP) process.

[0076] In this embodiment, the process parameters of the plasma chemical vapor deposition process also include: a radio frequency power range of 600W to 800W, and a chamber pressure range of 0.6Torr to 0.8Torr.

[0077] The plasma chemical vapor deposition process has a first deposition rate, the first deposition rate is in the range of to In this embodiment, the first deposition rate is

[0078] In this embodiment, the thickness of the temperature compensation layer ranges from 1 μm to 1.5 μm.

[0079] Figures 7 to 9 It is a structural schematic diagram of the formation process of a surface acoustic wave resonance device in another embodiment of the present invention.

[0080] Compared to the previous embodiment, in this embodiment, the temperature compensation layer further includes a second temperature compensation material layer, and the method for forming the temperature compensation layer further includes: before forming the first temperature compensation material layer, using a physical vapor deposition process to form the second temperature compensation material layer on the surface of the piezoelectric layer and the surface of the interdigitated electrode structure, and the first temperature compensation material layer is formed on the surface of the second temperature compensation material layer. For details, please refer to Figures 7 to 9 .

[0081] Please refer to Figure 7 , providing a substrate 300; forming an intermediate layer 301, bonding the substrate 300 and the piezoelectric layer 303 through the intermediate layer 301, the substrate 300 and the piezoelectric layer 303 are located on both sides of the intermediate layer 301; forming an interdigitated electrode structure 304 on the surface of the piezoelectric layer 303, the interdigitated electrode structure 304 includes a plurality of first electrode strips 304a and a plurality of second electrode strips 304b, the first electrode strips 304a and the second electrode strips 304b are parallel to a first direction (not shown in the figure), and are arranged at intervals along a second direction (not shown in the figure).

[0082] In this embodiment, a trap-rich layer 302 is further formed on the surface of the substrate 300 , and the trap-rich layer 302 is located between the intermediate layer 301 and the substrate 300 .

[0083] In this embodiment, the material of the trap-rich layer 302 includes polysilicon.

[0084] For the description of the formation method and structure of the intermediate layer 301 , the trap-rich layer 302 , the piezoelectric layer 303 and the interdigital electrode structure 304 , please refer to the previous embodiment and will not be described in detail here.

[0085] In this embodiment, the interdigitated electrode structure 304 has a first thickness, and the first thickness ranges from to In this embodiment, the first thickness is

[0086] In this embodiment, there is a first spacing between adjacent first electrode strips 304a and second electrode strips 304b, and the ratio of the first thickness to the first spacing is in a range of 2:1 to 30:1. There is a gap between the first electrode strips 304a and the second electrode strips 304b, and the ratio of the first thickness to the first spacing is the aspect ratio of the gap. For an interdigitated electrode structure with a high aspect ratio, when forming a temperature compensation layer, it is necessary to have good filling properties to improve the compactness of the formed temperature compensation layer.

[0087] Subsequently, a temperature compensation layer is formed on the piezoelectric layer 303 and the interdigital electrode structure 304 , the temperature compensation layer covers the interdigital electrode structure 304 , and the temperature compensation layer includes a first temperature compensation material layer and a second temperature compensation material layer.

[0088] In this embodiment, the method for forming the temperature compensation layer can be found in Figure 8 and Fig. 9 .

[0089] Please refer to Figure 8 A second temperature compensation material layer 305 is formed on the piezoelectric layer 303 by using a physical vapor deposition process, and the second temperature compensation material layer 305 at least covers the gap between the first electrode strip 304a and the second electrode 304b.

[0090] In this embodiment, the temperature compensation layer is composed of a second temperature compensation material layer 305 formed by a physical vapor deposition process and a first temperature compensation material layer formed by a subsequent plasma enhanced chemical vapor deposition process. The temperature compensation layer plays a role in temperature compensation, improves the characteristics of the resonant frequency of the surface acoustic wave resonator drifting with the operating temperature, and improves the performance of the surface acoustic wave resonator.

[0091] Compared with the previous embodiment, the second temperature compensation material layer 305 is formed by a physical vapor deposition process, which is beneficial to improving the filling capacity of the second temperature compensation material layer 305 in the interdigitated electrode structure 304, reducing the generation of voids, and improving the compactness of the second temperature compensation material layer 305. The quality of the formed temperature compensation layer is further improved, and the temperature coefficient of frequency (TCF) of the surface acoustic wave resonant device is improved, thereby improving the performance of the surface acoustic wave resonant device.

[0092] In this embodiment, the interdigitated electrode structure has a first thickness, the second temperature compensation material layer 305 has a second thickness, and the ratio of the second thickness to the first thickness is in the range of 1:2 to 2:1. The reason for selecting the ratio range of the second thickness to the first thickness is that: since the physical vapor deposition process has a low deposition rate and good filling capacity, and the plasma enhanced chemical vapor deposition process has a high deposition rate, when the total thickness requirement of the temperature compensation layer remains unchanged, the first thickness is reasonably selected, which can improve the filling capacity in the interdigitated electrode structure 304, and at the same time, better balance the film thickness uniformity, material film density and deposition rate of the temperature compensation layer, improve the overall performance of the temperature compensation layer, and thus help improve the performance of the surface acoustic wave resonance device.

[0093] Preferably, the ratio of the second thickness to the first thickness is 1.5.

[0094] The second thickness range is to In this embodiment, the second thickness is

[0095] The material of the temperature compensation layer includes silicon dioxide, silicon oxyfluoride, silicon oxynitride, and silicon oxycarbide.

[0096] In this embodiment, the material of the second temperature compensation material layer 305 includes silicon dioxide.

[0097] In this embodiment, the physical vapor deposition process includes a sputtering coating process, and the sputtering coating process has a second process temperature. The process parameters of the sputtering coating process include: the second process temperature ranges from 70°C to 80°C, the chamber gas pressure ranges from 950Torr to 1050Torr, and the RF power ranges from 290W to 310W.

[0098] Here, using a larger RF power is beneficial to improving the filling capacity of the second temperature compensation material layer 305 in the interdigital electrode structure 304, reducing the generation of voids, improving the compactness of the second temperature compensation material layer 305, and improving the reliability of the surface acoustic wave resonance device.

[0099] The physical vapor deposition process has a second deposition rate, and the second deposition rate is in the range of to In this embodiment, the second deposition rate is

[0100] Please refer to Fig. 9A plasma enhanced chemical vapor deposition process is used to form a first temperature compensation material layer 306 on the surface of the second temperature compensation material layer 305. The plasma enhanced chemical vapor deposition process uses tetraethyl orthosilicate as a reaction source. The plasma enhanced chemical vapor deposition process has a first process temperature, and the first process temperature ranges from 270°C to 400°C.

[0101] The method for forming the first temperature compensation material layer 306 is described in the previous embodiment and will not be elaborated here.

[0102] In this embodiment, the material of the first temperature compensation material layer 306 includes silicon dioxide.

[0103] In this embodiment, the interdigitated electrode structure 304 has a first thickness, the first temperature compensation material layer 306 has a third thickness, and the ratio of the third thickness to the first thickness ranges from 1:1 to 5:1.

[0104] In this embodiment, the third thickness ranges from 0.5 μm to 1 μm.

[0105] 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 protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for forming a surface acoustic wave resonator device, characterized in that: include: providing a substrate; forming an intermediate layer, through which the substrate and the piezoelectric layer are bonded, wherein the substrate and the piezoelectric layer are located on both sides of the intermediate layer; An interdigitated electrode structure is formed 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 the first electrode strips and the second electrode strips are parallel to the first direction and are arranged at intervals along the second direction; A temperature compensation layer is formed on the piezoelectric layer, the temperature compensation layer covers the interdigitated electrode structure, the temperature compensation layer includes a first temperature compensation material layer, and a method for forming the temperature compensation layer includes: using a plasma enhanced chemical vapor deposition process to form the first temperature compensation material layer on the piezoelectric layer and the interdigitated electrode structure, the plasma enhanced chemical vapor deposition process uses tetraethyl orthosilicate as a reaction source, the plasma enhanced chemical vapor deposition process has a first process temperature, and the first process temperature ranges from 270°C to 400°C.

2. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The process parameters of the plasma enhanced chemical vapor deposition process also include: a radio frequency power range of 600W to 800W, and a chamber pressure range of 0.6Torr to 0.8Torr.

3. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The plasma enhanced chemical vapor deposition process has a first deposition rate, the first deposition rate is in the range of to 4. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The temperature compensation layer also includes a second temperature compensation material layer, and the method for forming the temperature compensation layer also includes: before forming the first temperature compensation material layer, using a physical vapor deposition process to form the second temperature compensation material layer on the piezoelectric layer, the second temperature compensation material layer at least covers the gap between the first electrode strip and the second electrode, and the first temperature compensation material layer is formed on the surface of the second temperature compensation material layer.

5. The method for forming a surface acoustic wave resonator device according to claim 4, characterized in that: The physical vapor deposition process has a second deposition rate, and the second deposition rate is in the range of to 6. The method for forming a surface acoustic wave resonator device according to claim 4, wherein: The interdigital electrode structure has a first thickness, the second temperature compensation material layer has a second thickness, and a ratio of the second thickness to the first thickness ranges from 1:2 to 2:

1.

7. The method for forming a surface acoustic wave resonator device according to claim 6, wherein: The first thickness ranges from to The second thickness range is to 8. The method for forming a surface acoustic wave resonator device according to claim 4, wherein: The physical vapor deposition process includes a sputtering coating process, and the sputtering coating process has a second process temperature. The process parameters of the sputtering coating process include: the second process temperature ranges from 70°C to 80°C, the chamber gas pressure ranges from 950Torr to 1050Torr, and the RF power ranges from 290W to 310W.

9. The method for forming a surface acoustic wave resonator device according to claim 4, wherein: The interdigital electrode structure has a first thickness, the first temperature compensation material layer has a third thickness, and a ratio of the third thickness to the first thickness ranges from 1:1 to 5:

1.

10. The method for forming a surface acoustic wave resonator device according to claim 9, wherein: The third thickness ranges from 0.5 μm to 1 μm.

11. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The material of the temperature compensation layer includes silicon dioxide, silicon oxyfluoride, silicon oxynitride, and silicon oxycarbide.

12. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The interdigitated electrode structure has a first thickness, and adjacent first electrode strips and second electrode strips have a first spacing therebetween. The ratio of the first thickness to the first spacing ranges from 2:1 to 30:

1.

13. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The method further includes: performing a planarization process on the first temperature compensation material layer.

14. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The material of the substrate includes silicon or silicon carbide.

15. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: Also includes: forming a trap-rich layer on the surface of the substrate, wherein the trap-rich layer is located between the intermediate layer and the substrate; The material of the trap-rich layer includes polysilicon; and the process for forming the trap-rich layer includes a normal pressure chemical vapor deposition process or a low pressure chemical vapor deposition process.

16. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The material of the intermediate layer includes a dielectric material, and the dielectric material includes one or more of silicon dioxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon oxyfluoride, silicon carbonitride, and silicon carbon oxynitride.

17. The method for forming a surface acoustic wave resonator device according to claim 1, wherein: The intermediate layer is formed on the substrate; the method for forming the intermediate layer includes a plasma enhanced chemical vapor deposition process or a physical vapor deposition process.

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